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Jaswant Singh–Bhattacharji stain , commonly referred to as JSB stain , is a rapid staining method for detection of malaria . [ 1 ] [ 2 ] It is useful for the diagnosis of malaria in thick smear samples of blood. [ 3 ] The JSB stain is commonly used throughout India , but rarely used in other countries. [ 4 ]
The JSB stain consists of two solutions which are used in sequence to stain various parts of the sample. The first solution consists of methylene blue , potassium dichromate , and sulfuric acid diluted in water. This solution is heated for several hours to oxidize the methylene blue. The second solution is eosin dissolved in water. [ 5 ] | https://en.wikipedia.org/wiki/Jaswant_Singh–Bhattacharji_stain |
java.net was [ 1 ] a Java technology related community website. It also offered a web-based source code repository for Java projects. It was shut down in April 2017.
java.net was announced by Sun Microsystems during JavaOne 2003. [ 2 ] [ 3 ]
In January 2010, Oracle announced that it will migrate java.net portal to Project Kenai codebase, encouraging users to move their Kenai projects to java.net. [ 4 ] [ 5 ] [ 6 ]
In June 2016, Oracle announced that "the Java.net and Kenai.com forges will be going dark on April 28, 2017." [ 7 ]
The Javapedia project was launched in June 2003 during the JavaOne developer conference. [ 8 ] [ 9 ] It is part of java.net.
The project aims at creating an online encyclopedia covering all aspects of the Java platform . [ 10 ] The Javapedia project is openly inspired by Wikipedia. [ 11 ]
The prominent differences between Wikipedia and Javapedia include feature restrictions (for example, editing is open to registered users only), software used ( TWiki ), links ( camelCase is used), and content licensing ( Creative Commons 1.0 Attribution license ).
This article about a computing website is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Java.net |
JavaPOS (short for Java for Point of Sale Devices ), is a standard for interfacing point of sale (POS) software, written in Java , with the specialized hardware peripherals typically used to create a point-of-sale system. The advantages are reduced POS terminal costs, platform independence, and reduced administrative costs. JavaPOS was based on a Windows POS device driver standard known as OPOS . [ 1 ] JavaPOS and OPOS have since been folded into a common UnifiedPOS standard.
JavaPOS can be used to access various types of POS hardware. A few of the hardware types that can be controlled using JavaPOS are
In addition to referring to the standard, the term JavaPOS is used to refer to the application programming interface (API).
The JavaPOS standard includes definitions for "Control Objects" and "Service Objects". The POS software communicates with the Control Objects. The Control Objects load and communicate with appropriate Service Objects. The Service Objects are sometimes referred to as the "JavaPOS drivers."
The POS software interacts with the control object to control the hardware device. A common JavaPOS library is published by the standards organization with an implementation of the Control Objects of the JavaPOS standard. [ 1 ]
Each hardware vendor is responsible for providing Service Objects, or "JavaPOS drivers" for the hardware they sell. Depending on the vendor, drivers may be available that can communicate over USB , RS-232 , RS-485 , or even an Ethernet connection. The hardware vendors will typically create JavaPOS drivers that will work with Windows. The majority of vendors will also create drivers for at least one flavor of Linux, but not as many. Since there is not nearly as much marketshare to capture for Apple computers used as POS systems, only a few JavaPOS drivers would be expected to work with Mac OS X. (And those would be more likely due to happy circumstance rather than careful design.)
The committee that initiated JavaPOS development consisted of Sun Microsystems , IBM , and NCR . [ 2 ] The first meeting occurred in April, 1997 and the first release, JavaPOS 1.2, occurred on 28 March 1998. [ 2 ] [ 3 ] The final release as a separate standard was version 1.6 in July 2001. Beginning with release 1.7, a single standards document was released by a UnifiedPOS committee. That standards document is then used to create the common JavaPOS libraries for the release. [ 3 ] | https://en.wikipedia.org/wiki/JavaPOS |
Java APIs for Integrated Networks ( JAIN ) is an activity within the Java Community Process , developing APIs for the creation of telephony (voice and data) services. Originally, JAIN stood for Java APIs for Intelligent Network . The name was later changed to Java APIs for Integrated Networks to reflect the widening scope of the project. The JAIN activity consists of a number of "Expert Groups", each developing a single API specification.
JAIN is part of a general trend to open up service creation in the telephony network so that, by analogy with the Internet , openness should result in a growing number of participants creating services, in turn creating more demand and better, more targeted services.
A goal of the JAIN APIs is to abstract the underlying network, so that services can be developed independent of network technology, be it traditional PSTN or Next Generation Network .
The JAIN effort has produced around 20 APIs, in various stages of standardization, ranging from Java APIs for specific network protocols , such as SIP and TCAP , to more abstract APIs such as for call control and charging , and even including a non-Java effort for describing telephony services in XML .
There is overlap between JAIN and Parlay / OSA because both address similar problem spaces. However, as originally conceived, JAIN focused on APIs that would make it easier for network operators to develop their own services within the framework of Intelligent Network (IN) protocols. As a consequence, the first JAIN APIs focused on methods for building and interpreting SS7 messages and it was only later that JAIN turned its attention to higher-level methods for call control. Meanwhile, at about the same time JAIN was getting off the ground, work on Parlay began with a focus on APIs to enable development of network services by non-operator third parties.
From around 2001 to 2003, there was an effort to harmonize the not yet standardized JAIN APIs for call control with the comparable and by then standardized Parlay APIs. A number of difficulties were encountered, but perhaps the most serious was not technical but procedural. The Java Community Process requires that a reference implementation be built for every standardized Java API. Parlay does not have this requirement. Not surprisingly, given the effort that would have been needed to build a reference implementation of JAIN call control, the standards community decided, implicitly if not explicitly, that the Parlay call control APIs were adequate and work on JAIN call control faded off. Nonetheless, the work on JAIN call control did have an important impact on Parlay since it helped to drive the definition of an agreed-upon mapping of Parlay to the Java language. | https://en.wikipedia.org/wiki/Java_APIs_for_Integrated_Networks |
Java Agent Template (JAT) , is a fully functional Java template, for building software agents that can communicate in a P2P distributed network over the Internet . [ 1 ] [ 2 ]
This computing article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Java_Agent_Template |
Java Platform, Micro Edition or Java ME is a computing platform for development and deployment of portable code for embedded and mobile devices (micro-controllers, sensors, gateways, mobile phones, personal digital assistants, TV set-top boxes, printers). [ 1 ] Java ME was formerly known as Java 2 Platform, Micro Edition or J2ME .
The platform uses the object-oriented Java programming language, and is part of the Java software-platform family. It was designed by Sun Microsystems (now Oracle Corporation ) and replaced a similar technology, PersonalJava .
In 2013, with more than 3 billion Java ME enabled mobile phones in the market, [ 2 ] the platform was in continued decline as smartphones have overtaken feature phones. [ 3 ]
The platform used to be popular in feature phones, such as Nokia's Series 40 models. It was also supported on the Bada operating system and on Symbian OS along with native software. Users of Windows CE , Windows Mobile , Maemo , MeeGo and Android could download Java ME for their respective environments ("proof-of-concept" for Android). [ 4 ] [ 5 ]
Originally developed under the Java Community Process as JSR 68, the different flavors of Java ME have evolved in separate JSRs. Java ME devices implement a profile . The most common of these are the Mobile Information Device Profile aimed at mobile devices such as cell phones, and the Personal Profile aimed at consumer products and embedded devices like set-top boxes and PDAs. Profiles are subsets of configurations , of which there are currently two: the Connected Limited Device Configuration (CLDC) and the Connected Device Configuration (CDC). [ 6 ]
In 2008, Java ME platforms were restricted to JRE 1.3 features and use that version of the class file format (internally known as version 47.0).
Oracle provides a reference implementation of the specification, and some configurations and profiles for MIDP and CDC. Starting with the JavaME 3.0 SDK, a NetBeans -based IDE supported them in a single IDE.
In contrast to the numerous binary implementations of the Java Platform built by Sun for servers and workstations, Sun tended not to provide binaries for the platforms of Java ME targets, and instead relied on third parties to provide their own.
The exception was an MIDP 1.0 JRE (JVM) for Palm OS. [ 7 ] Sun provides no J2ME JRE for the Microsoft Windows Mobile (Pocket PC) based devices, despite an open-letter campaign to Sun to release a rumored internal implementation of PersonalJava known by the code name "Captain America". [ 8 ] Third party implementations are widely used by Windows Mobile vendors.
At some point, Sun released a now-abandoned reference implementation under the name phoneME .
Operating systems targeting Java ME have been implemented by DoCoMo in the form of DoJa , and by SavaJe as SavaJe OS. The latter company was purchased by Sun in April 2007 and now forms the basis of Sun's JavaFX Mobile .
The open-source Mika VM aims to implement JavaME CDC/FP, but is not certified as such (certified implementations are required to charge royalties, which is impractical for an open-source project). Consequently, devices which use this implementation are not allowed to claim JavaME CDC compatibility.
The Linux-based Android operating system uses a proprietary version of Java that is similar in intent, but very different in many ways from Java ME. [ 9 ]
There are other emulators, including emulators provided as part of development kits by phone manufacturers, such as Nokia, Sony-Ericsson , Siemens Mobile, etc.
The Connected Limited Device Configuration (CLDC) contains a strict subset of the Java-class libraries, and is the minimum amount needed for a Java virtual machine to operate. CLDC is basically used for classifying myriad devices into a fixed configuration.
A configuration provides the most basic set of libraries and virtual-machine features that must be present in each implementation of a J2ME environment. When coupled with one or more profiles, the Connected Limited Device Configuration gives developers a solid Java platform for creating applications for consumer and embedded devices.
The configuration is designed for devices with 160KB to 512KB total memory, which has a minimum of 160KB of ROM and 32KB of RAM available for the Java platform.
Designed for mobile phones, the Mobile Information Device Profile includes a GUI , and a data storage API, and MIDP 2.0 includes a basic 2D gaming API . Applications written for this profile are called MIDlets .
JSR 271: Mobile Information Device Profile 3 (Final release on Dec 9, 2009) specified the 3rd generation Mobile Information Device Profile (MIDP3), expanding upon the functionality in all areas as well as improving interoperability across devices. A key design goal of MIDP3 is backward compatibility with MIDP2 content.
The Information Module Profile (IMP) is a profile for embedded, "headless" devices such as vending machines, industrial embedded applications, security systems, and similar devices with either simple or no display and with some limited network connectivity.
Originally introduced by Siemens Mobile and Nokia as JSR -195, IMP 1.0 is a strict subset of MIDP 1.0 except that it does not include user interface APIs — in other words, it does not include support for the Java package javax.microedition.lcdui . JSR-228, also known as IMP-NG, is IMP's next generation that is based on MIDP 2.0, leveraging MIDP 2.0's new security and networking types and APIs, and other APIs such as PushRegistry and platformRequest() , but again it does not include UI APIs, nor the game API.
The Connected Device Configuration is a subset of Java SE , containing almost all the libraries that are not GUI related. It is richer than CLDC.
The Foundation Profile is a Java ME Connected Device Configuration (CDC) profile. This profile is intended to be used by devices requiring a complete implementation of the Java virtual machine up to and including the entire Java Platform, Standard Edition API. Typical implementations will use some subset of that API set depending on the additional profiles supported. This specification was developed under the Java Community Process.
The Personal Basis Profile extends the Foundation Profile to include lightweight GUI support in the form of an AWT subset. This is the platform that BD-J is built upon.
The ESR consortium is devoted to Standards for embedded Java. Especially cost effective Standards.
Typical applications domains are industrial control, machine-to-machine, medical, e-metering, home automation , consumer, human-to-machine-interface, ... | https://en.wikipedia.org/wiki/Java_Platform,_Micro_Edition |
Java Platform, Standard Edition ( Java SE ) is a computing platform for development and deployment of portable code for desktop and server environments. [ 1 ] Java SE was formerly known as Java 2 Platform, Standard Edition ( J2SE ).
The platform uses the Java programming language and is part of the Java software-platform family. Java SE defines a range of general-purpose APIs —such as Java APIs for the Java Class Library —and also includes the Java Language Specification and the Java Virtual Machine Specification . [ 2 ] OpenJDK is the official reference implementation since version 7. [ 3 ] [ 4 ] [ 5 ]
The platform was known as Java 2 Platform, Standard Edition or J2SE from version 1.2, until the name was changed to Java Platform, Standard Edition or Java SE in version 1.5. The "SE" is used to distinguish the base platform from the Enterprise Edition ( Java EE ) and Micro Edition ( Java ME ) platforms. The "2" was originally intended to emphasize the major changes introduced in version 1.2, but was removed in version 1.6. The naming convention has been changed several times over the Java version history . Starting with J2SE 1.4 (Merlin), Java SE has been developed under the Java Community Process , which produces descriptions of proposed and final specifications for the Java platform called Java Specification Requests (JSR) . [ 6 ] JSR 59 was the umbrella specification for J2SE 1.4 and JSR 176 specified J2SE 5.0 (Tiger). Java SE 6 (Mustang) was released under JSR 270.
Java Platform, Enterprise Edition (Java EE) is a related specification that includes all the classes in Java SE, plus a number that are more useful to programs that run on servers as opposed to workstations .
Java Platform, Micro Edition (Java ME) is a related specification intended to provide a certified collection of Java APIs for the development of software for small, resource-constrained devices such as cell phones , PDAs and set-top boxes .
The Java Runtime Environment (JRE) and Java Development Kit (JDK) are the actual files downloaded and installed on a computer to run or develop Java programs, respectively.
The majority of these packages are exported by the java.base module of the Java Platform Module System (since Java 9).
The Java package java.lang contains fundamental classes and interfaces closely tied to the language and runtime system. This includes the root classes that form the class hierarchy , types tied to the language definition, basic exceptions , math functions, threading , security functions, as well as some information on the underlying native system. This package contains 22 of 32 Error classes provided in JDK 6.
The main classes and interfaces in java.lang are:
Classes in java.lang are automatically imported into every source file .
The java.lang.ref package provides more flexible types of references than are otherwise available, permitting limited interaction between the application and the Java Virtual Machine (JVM) garbage collector . It is an important package, central enough to the language for the language designers to give it a name that starts with "java.lang", but it is somewhat special-purpose and not used by a lot of developers. This package was added in J2SE 1.2.
Java has an expressive system of references and allows for special behavior for garbage collection. A normal reference in Java is known as a "strong reference". The java.lang.ref package defines three other types of references—soft, weak , and phantom references. Each type of reference is designed for a specific use.
Each of these reference types extends the Reference class, which provides the get() method to return a strong reference to the referent object (or null if the reference has been cleared or if the reference type is phantom), and the clear() method to clear the reference.
The java.lang.ref also defines the class ReferenceQueue , which can be used in each of the applications discussed above to keep track of objects that have changed reference type. When a Reference is created it is optionally registered with a reference queue. The application polls the reference queue to get references that have changed reachability state.
Reflection is a constituent of the Java API that lets Java code examine and "reflect" on Java components at runtime and use the reflected members. Classes in the java.lang.reflect package, along with java.lang.Class and java.lang.Package accommodate applications such as debuggers , interpreters , object inspectors, class browsers , and services such as object serialization and JavaBeans that need access to either the public members of a target object (based on its runtime class) or the members declared by a given class. This package was added in JDK 1.1.
Reflection is used to instantiate classes and invoke methods using their names, a concept that allows for dynamic programming. Classes, interfaces, methods, fields , and constructors can all be discovered and used at runtime. Reflection is supported by metadata that the JVM has about the program.
There are basic techniques involved in reflection:
Discovery typically starts with an object and calling the Object.getClass() method to get the object's Class . The Class object has several methods for discovering the contents of the class, for example:
The Class object can be obtained either through discovery, by using the class literal (e.g. MyClass.class ) or by using the name of the class (e.g. Class.forName("mypackage.MyClass") ). With a Class object, member Method , Constructor , or Field objects can be obtained using the symbolic name of the member. For example:
Method , Constructor , and Field objects can be used to dynamically access the represented member of the class. For example:
The java.lang.reflect package also provides an Array class that contains static methods for creating and manipulating array objects, and since J2SE 1.3, a Proxy class that supports dynamic creation of proxy classes that implement specified interfaces.
The implementation of a Proxy class is provided by a supplied object that implements the InvocationHandler interface. The InvocationHandler 's invoke(Object, Method, Object[]) method is called for each method invoked on the proxy object—the first parameter is the proxy object, the second parameter is the Method object representing the method from the interface implemented by the proxy, and the third parameter is the array of parameters passed to the interface method. The invoke() method returns an Object result that contains the result returned to the code that called the proxy interface method.
The java.io package contains classes that support input and output . The classes in the package are primarily stream-oriented ; however, a class for random access files is also provided. The central classes in the package are InputStream and OutputStream , which are abstract base classes for reading from and writing to byte streams , respectively. The related classes Reader and Writer are abstract base classes for reading from and writing to character streams, respectively. The package also has a few miscellaneous classes to support interactions with the host file system .
The stream classes follow the decorator pattern by extending the base subclass to add features to the stream classes. Subclasses of the base stream classes are typically named for one of the following attributes:
The stream subclasses are named using the naming pattern XxxStreamType where Xxx is the name describing the feature and StreamType is one of InputStream , OutputStream , Reader , or Writer .
The following table shows the sources/destinations supported directly by the java.io package:
Other standard library packages provide stream implementations for other destinations, such as the InputStream returned by the java.net.Socket.getInputStream() method or the Java EE javax.servlet.ServletOutputStream class.
Data type handling and processing or filtering of stream data is accomplished through stream filters . The filter classes all accept another compatible stream object as a parameter to the constructor and decorate the enclosed stream with additional features. Filters are created by extending one of the base filter classes FilterInputStream , FilterOutputStream , FilterReader , or FilterWriter .
The Reader and Writer classes are really just byte streams with additional processing performed on the data stream to convert the bytes to characters. They use the default character encoding for the platform, which as of J2SE 5.0 is represented by the Charset returned by the java.nio.charset.Charset.defaultCharset() static method. The InputStreamReader class converts an InputStream to a Reader and the OutputStreamWriter class converts an OutputStream to a Writer . Both these classes have constructors that support specifying the character encoding to use. If no encoding is specified, the program uses the default encoding for the platform.
The following table shows the other processes and filters that the java.io package directly supports. All these classes extend the corresponding Filter class.
The RandomAccessFile class supports random access reading and writing of files. The class uses a file pointer that represents a byte-offset within the file for the next read or write operation. The file pointer is moved implicitly by reading or writing and explicitly by calling the seek(long) or skipBytes(int) methods. The current position of the file pointer is returned by the getFilePointer() method.
The File class represents a file or directory path in a file system . File objects support the creation, deletion and renaming of files and directories and the manipulation of file attributes such as read-only and last modified timestamp . File objects that represent directories can be used to get a list of all the contained files and directories.
The FileDescriptor class is a file descriptor that represents a source or sink (destination) of bytes. Typically this is a file, but can also be a console or network socket . FileDescriptor objects are used to create File streams. They are obtained from File streams and java.net sockets and datagram sockets.
In J2SE 1.4, the package java.nio (NIO or Non-blocking I/O) was added to support memory-mapped I/O , facilitating I/O operations closer to the underlying hardware with sometimes dramatically better performance. The java.nio package provides support for a number of buffer types. The subpackage java.nio.charset provides support for different character encodings for character data. The subpackage java.nio.channels provides support for channels, which represent connections to entities that are capable of performing I/O operations, such as files and sockets. The java.nio.channels package also provides support for fine-grained locking of files.
The java.math package supports multiprecision arithmetic (including modular arithmetic operations) and provides multiprecision prime number generators used for cryptographic key generation. The main classes of the package are:
The java.net package provides special IO routines for networks, allowing HTTP requests, as well as other common transactions.
The java.text package implements parsing routines for strings and supports various human-readable languages and locale-specific parsing.
Data structures that aggregate objects are the focus of the java.util package. Included in the package is the Collections API , an organized data structure hierarchy influenced heavily by the design patterns considerations.
Created to support Java applet creation, the java.applet package lets applications be downloaded over a network and run within a guarded sandbox. Security restrictions are easily imposed on the sandbox. A developer, for example, may apply a digital signature to an applet, thereby labeling it as safe. Doing so allows the user to grant the applet permission to perform restricted operations (such as accessing the local hard drive), and removes some or all the sandbox restrictions. Digital certificates are issued by certificate authorities .
Because Java applets are now deprecated, this package is itself deprecated.
Included in the java.beans package are various classes for developing and manipulating beans, reusable components defined by the JavaBeans architecture . The architecture provides mechanisms for manipulating properties of components and firing events when those properties change.
The APIs in java.beans are intended for use by a bean editing tool, in which beans can be combined, customized, and manipulated. One type of bean editor is a GUI designer in an integrated development environment .
The java.awt , or Abstract Window Toolkit, provides access to a basic set of GUI widgets based on the underlying native platform's widget set, the core of the GUI event subsystem, and the interface between the native windowing system and the Java application. It also provides several basic layout managers , a datatransfer package for use with the Clipboard and Drag and Drop , the interface to input devices such as mice and keyboards , as well as access to the system tray on supporting systems. This package, along with javax.swing contains the largest number of enums (7 in all) in JDK 6.
The java.rmi package provides Java remote method invocation to support remote procedure calls between two java applications running in different JVMs .
Support for security, including the message digest algorithm, is included in the java.security package.
An implementation of the JDBC API (used to access SQL databases ) is grouped into the java.sql package.
The javax.rmi package provided support for the remote communication between applications, using the RMI over IIOP protocol. This protocol combines RMI and CORBA features.
Java SE Core Technologies - CORBA / RMI-IIOP
Swing is a collection of routines that build on java.awt to provide a platform independent widget toolkit . javax.swing uses the 2D drawing routines to render the user interface components instead of relying on the underlying native operating system GUI support.
This package contains the largest number of classes (133 in all) in JDK 6. This package, along with java.awt also contains the largest number of enums (7 in all) in JDK 6. It supports pluggable looks and feels (PLAFs) so that widgets in the GUI can imitate those from the underlying native system. Design patterns permeate the system, especially a modification of the model–view–controller pattern, which loosens the coupling between function and appearance. One inconsistency is that (as of J2SE 1.3) fonts are drawn by the underlying native system, and not by Java, limiting text portability. Workarounds, such as using bitmap fonts, do exist. In general, "layouts" are used and keep elements within an aesthetically consistent GUI across platforms.
The javax.swing.text.html.parser package provides the error tolerant HTML parser that is used for writing various web browsers and web bots.
The javax.xml.bind.annotation package contained the largest number of Annotation Types (30 in all) in JDK 6. It defines annotations for customizing Java program elements to XML Schema mapping.
The org.omg.CORBA package provided support for the remote communication between applications using the General Inter-ORB Protocol and supports other features of the common object request broker architecture . Same as RMI and RMI-IIOP , this package is for calling remote methods of objects on other virtual machines (usually via network).
This package contained the largest number of Exception classes (45 in all) in JDK 6. From all communication possibilities CORBA is portable between various languages; however, with this comes more complexity.
These packages were deprecated in Java 9 and removed from Java 11. [ 7 ]
The org.omg.PortableInterceptor package contained the largest number of interfaces (39 in all) in JDK 6. It provides a mechanism to register ORB hooks through which ORB services intercept the normal flow of execution of the ORB.
Several critical security vulnerabilities have been reported. [ 8 ] [ 9 ] Security alerts from Oracle announce critical security-related patches to Java SE. [ 10 ] | https://en.wikipedia.org/wiki/Java_Platform,_Standard_Edition |
The Java Research License ( JRL ) is a software distribution license created by Sun in an effort to simplify and relax the terms from the "research section" of the Sun Community Source License . Sun's J2SE 1.6.0, Mustang , is licensed under the JRL as well as many projects at Java.net .
The JRL was introduced in 2003 to try to "make things a lot more friendly to people doing academic research" into the Java language, [ 1 ] before the core of Java was made open source in 2006. [ 2 ]
Although the JRL has elements of an open source license, the terms forbid any commercial use and are thus incompatible with both the Free Software Definition and the Open Source Definition . The JRL is a research license to be used for non-commercial academic uses.
This programming-language -related article is a stub . You can help Wikipedia by expanding it .
This law -related article is a stub . You can help Wikipedia by expanding it .
This software article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Java_Research_License |
A Java logging framework is a computer data logging package for the Java platform . This article covers general purpose logging frameworks.
Logging refers to the recording of activity by an application and is a common issue for development teams. Logging frameworks ease and standardize the process of logging for the Java platform. In particular they provide flexibility by avoiding explicit output to the console (see Appender below). Where logs are written becomes independent of the code and can be customized at runtime.
Unfortunately the JDK did not include logging in its original release so by the time the Java Logging API was added several other logging frameworks had become widely used – in particular Apache Commons Logging (also known as Java Commons Logging or JCL) and Log4j . This led to problems when integrating different third-party libraries (JARs) each using different logging frameworks. Pluggable logging frameworks (wrappers) were developed to solve this problem.
Logging is typically broken into three major pieces: the Logger, the Formatter and the Appender (or Handler).
Simpler logging frameworks, like |Java Logging Framework by the Object Guy , combine the logger and the appender. This simplifies default operation, but it is less configurable, especially if the project is moved across environments.
A Logger is an object that allows the application to log without regard to where the output is sent/stored. The application logs a message by passing an object or an object and an exception with an optional severity level to the logger object under a given name/identifier.
A logger has a name. The name is usually structured hierarchically, with periods (.) separating the levels. A common scheme is to use the name of the class or package that is doing the logging. Both Log4j and the Java logging API support defining handlers higher up the hierarchy.
For example, the logger might be named " com.sun.some.UsefulClass ". The handler can be defined for any of the following:
As long as there is a handler defined somewhere in this stack, logging may occur. For example a message logged to the com.sun.some.UsefulClass logger, may get written by the com.sun handler. Typically there is a global handler that receives and processes messages generated by any logger.
The message is logged at a certain level. Common level names are copied from Apache Commons Logging (although the Java Logging API defines different level names):
The logging framework maintains the current logging level for each logger. The logging level can be set more or less restrictive. For example, if the logging level is set to "WARNING", then all messages of that level or higher are logged: ERROR and FATAL.
Severity levels can be assigned to both loggers and appenders. Both must be enabled for a given severity level for output to be generated. So a logger enabled for debug output will not generate output if the handler that gets the message is not also enabled for debug.
Filters cause a log event to be ignored or logged. The most commonly used filter is the logging level documented in the previous section. Logging frameworks such as Log4j 2 and SLF4J also provide Markers, which when attached to a log event can also be used for filtering. Filters can also be used to accept or deny log events based on exceptions being thrown, data within the log message, data in a ThreadLocal that is exposed through the logging API, or a variety of other methods.
A Formatter is an object that formats a given object. Mostly this consists of taking the binary object and converting it to a string representation. Each framework defines a default output format that can be overridden if desired.
Appenders listen for messages at or above a specified minimum severity level. The Appender takes the message it is passed and posts it appropriately. Message dispositions include:
JCL and Log4j are very common simply because they have been around for so long and were the only choices for a long time. The flexibility of slf4j (using Logback underneath) has made it a popular choice.
SLF4J is a set of logging wrappers (or shims) that allow it to imitate any of the other frameworks. Thus multiple third-party libraries can be incorporated into an application, regardless of the logging framework each has chosen to use. However all logging output is generated in a standard way, typically via Logback.
Log4j 2 provides both an API and an implementation. The API can be routed to other logging implementations equivalent to how SLF4J works. Unlike SLF4J, the Log4j 2 API logs Message [ 2 ] objects instead of Strings for extra flexibility and also supports Java Lambda expressions. [ 3 ]
JCL isn't really a logging framework, but a wrapper for one. As such, it requires a logging framework underneath it, although it can default to using its own SimpleLog logger.
JCL, SLF4J and the Log4j 2 API are useful when developing reusable libraries which need to write to whichever underlying logging system is being used by the application. This also provides flexibility in heterogeneous environments where the logging framework is likely to change, although in most cases, once a logging framework has been chosen, there is little need to change it over the life of the project. SLF4J and Log4j 2 benefit from being newer and build on the lessons learned from older frameworks. Moreover JCL has known problems with class-loaders when determining what logging library it should wrap [ 4 ] which has now replaced JCL. [ 5 ]
The Java Logging API is provided with Java. Although the API is technically separate from the default implementation provided with Java, replacing it with an alternate implementation can be challenging so many developers confuse this implementation with the Java Logging API. Configuration is by external files only which is not easily changed on the fly (other frameworks support programmatic configuration). The default implementation only provides a few Handlers and Formatters which means most users will have to write their own. [ 6 ] | https://en.wikipedia.org/wiki/Java_logging_framework |
The Java language has undergone several changes since JDK 1.0 as well as numerous additions of classes and packages to the standard library . Since J2SE 1.4, the evolution of the Java language has been governed by the Java Community Process (JCP), which uses Java Specification Requests (JSRs) to propose and specify additions and changes to the Java platform . The language is specified by the Java Language Specification (JLS); changes to the JLS are managed under JSR 901 . In September 2017, Mark Reinhold, chief Architect of the Java Platform, proposed to change the release train to "one feature release every six months" rather than the then-current two-year schedule. [ 1 ] [ 2 ] This proposal took effect for all following versions, and is still the current release schedule.
In addition to the language changes, other changes have been made to the Java Class Library over the years, which has grown from a few hundred classes in JDK 1.0 to over three thousand in J2SE 5. Entire new APIs , such as Swing and Java2D , have been introduced, and many of the original JDK 1.0 classes and methods have been deprecated , and very few APIs have been removed (at least one, for threading, in Java 22 [ 3 ] ). Some programs allow the conversion of Java programs from one version of the Java platform to an older one (for example Java 5.0 backported to 1.4) (see Java backporting tools ).
Regarding Oracle's Java SE support roadmap, [ 4 ] Java SE 23 is the latest version, while versions 21, 17, 11 and 8 are the currently supported long-term support (LTS) versions, where Oracle Customers will receive Oracle Premier Support. Oracle continues to release no-cost public Java 8 updates for development [ 4 ] and personal use indefinitely. Oracle also continues to release no-cost public Java 17 LTS updates for all users, including commercial and production use until September 2024. [ 5 ]
In the case of OpenJDK , both commercial long-term support and free software updates are available from multiple organizations in the broader community . [ 6 ]
Java 23 was released on 17 September 2024. Java 24 was released on 18 March 2025. [ 7 ]
The first version was released on January 23, 1996. [ 20 ] [ 21 ] The first stable version, JDK 1.0.2, is called Java 1. [ 21 ]
Major additions in the release on February 19, 1997 included: [ 22 ]
The release on December 8, 1998 and subsequent releases through J2SE 5.0 were rebranded retrospectively Java 2 and the version name "J2SE" ( Java 2 Platform, Standard Edition ) replaced JDK to distinguish the base platform from J2EE ( Java 2 Platform, Enterprise Edition ) and J2ME ( Java 2 Platform, Micro Edition ). This was a very significant release of Java as it tripled the size of the Java platform to 1520 classes in 59 packages. Major additions included: [ 24 ]
The most notable changes in the May 8, 2000 release were: [ 25 ] [ 26 ]
Java 1.3 is the last release of Java to officially support Microsoft Windows 95 . [ 27 ]
The February 6, 2002 release was the first release of the Java platform developed under the Java Community Process as JSR 59 . Major changes included: [ 28 ] [ 29 ]
Public support and security updates for Java 1.4 ended in October 2008. Paid security updates for Oracle customers ended in February 2013. [ 30 ]
The release on September 30, 2004 was originally numbered 1.5, which is still used as the internal version number. The number was changed to "better reflect the level of maturity, stability, scalability and security of the J2SE". [ 31 ] This version was developed under JSR 176 .
Java SE 5 entered its end-of-public-updates period on April 8, 2008; updates are no longer available to the public as of November 3, 2009. Updates were available to paid Oracle customers until May 2015. [ 4 ]
Tiger added a number of significant new language features: [ 32 ] [ 33 ]
There were also the following improvements to the standard libraries:
Java 5 is the last release of Java to officially support Microsoft Windows 98 and Windows ME , [ 36 ] while Windows Vista was the newest version of Windows that Java SE 5 was supported on prior to Java 5 going end-of-life in October 2009. [ 30 ]
Java 5 Update 5 (1.5.0_05) is the last release of Java to work on Windows 95 (with Internet Explorer 5 .5 installed) and Windows NT 4.0 . [ 37 ]
Java 5 was first available on Apple Mac OS X 10.4 (Tiger) [ 38 ] and was the default version of Java installed on Apple Mac OS X 10.5 (Leopard).
Public support and security updates for Java 1.5 ended in November 2009. Paid security updates for Oracle customers ended in April 2015.
This version introduced a new versioning system for the Java language, although the old versioning system continued to be used for developer libraries:
Both version numbers "1.5.0" and "5.0" are used to identify this release of the Java 2 Platform Standard Edition. Version "5.0" is the product version, while "1.5.0" is the developer version. The number "5.0" is used to better reflect the level of maturity, stability, scalability and security of the J2SE.
This correspondence continued through later releases (Java 6 = JDK 1.6, Java 7 = JDK 1.7, and so on).
As of the version released on December 11, 2006, Sun replaced the name "J2SE" with Java SE and dropped the ".0" from the version number. [ 40 ] Internal numbering for developers remains 1.6.0. [ 41 ]
This version was developed under JSR 270 .
During the development phase, new builds including enhancements and bug fixes were released approximately weekly. Beta versions were released in February and June 2006, leading up to a final release that occurred on December 11, 2006.
Major changes included in this version: [ 42 ] [ 43 ]
Java 6 can be installed to Mac OS X 10.5 (Leopard) running on 64-bit (Core 2 Duo and higher) processor machines. [ 47 ] Java 6 is also supported by both 32-bit and 64-bit machines running Mac OS X 10.6 (Snow Leopard).
Java 6 reached the end of its supported life in February 2013, at which time all public updates, including security updates, were scheduled to be stopped. [ 48 ] [ 49 ] Oracle released two more updates to Java 6 in March and April 2013, which patched some security vulnerabilities. [ 50 ] [ 51 ]
After Java 6 release, Sun, and later Oracle, released several updates which, while not changing any public API, enhanced end-user usability or fixed bugs. [ 52 ]
The -XX:+DoEscapeAnalysis option directs the HotSpot JIT compiler to use escape analysis to determine whether local objects can be allocated on the stack instead of the heap . [ citation needed ]
Some developers have noticed an issue introduced in this release which causes debuggers to miss breakpoints seemingly randomly. [ 58 ] Sun has a corresponding bug, which is tracking the issue. The workaround applies to the Client and Server VMs. [ 59 ] Using the -XX:+UseParallelGC option will prevent the failure. Another workaround is to roll back to update 13, or to upgrade to update 16.
Java 7 was a major update that launched on July 7, 2011 [ 90 ] and was made available for developers on July 28, 2011. [ 91 ] The development period was organized into thirteen milestones; on June 6, 2011, the last of the thirteen milestones was finished. [ 91 ] [ 92 ] On average, 8 builds (which generally included enhancements and bug fixes) were released per milestone. The feature list at the OpenJDK 7 project lists many of the changes.
Additions in Java 7 include: [ 93 ]
Lambda (Java's implementation of lambda functions ), Jigsaw (Java's implementation of modules ), and part of Coin were dropped from Java 7, and released as part of Java 8 (except for Jigsaw , which was released in Java 9). [ 110 ] [ 111 ]
Java 7 was the default version to download on java.com from April 2012 until Java 8 was released. [ 112 ]
Oracle issued public updates to the Java 7 family on a quarterly basis [ 113 ] until April 2015 when the product reached the end of its public availability. [ 114 ] Further updates for JDK 7, which continued until July 2022, are only made available to customers with a support contract. [ 115 ]
Java 8 was released on March 18, 2014, [ 151 ] [ 152 ] and included some features that were planned for Java 7 but later deferred. [ 153 ]
Work on features was organized in terms of JDK Enhancement Proposals (JEPs). [ 154 ]
Java 8 is not supported on Windows XP [ 163 ] but as of JDK 8 update 25, it can still be installed and run under Windows XP. [ 164 ] Previous updates of JDK 8 could be run under XP by downloading archived zip format file and unzipping it for the executable. The last version of Java 8 could run on XP is update 251.
From October 2014, Java 8 was the default version to download (and then again the download replacing Java 9) from the official website. [ 165 ] "Oracle will continue to provide Public Updates and auto updates of Java SE 8, Indefinitely for Personal Users". [ 166 ]
Java SE 9 was made available on September 21, 2017 [ 247 ] due to controversial acceptance of the current implementation of Project Jigsaw by Java Executive Committee [ 248 ] which led Oracle to fix some open issues and concerns and to refine some critical technical questions. In the last days of June 2017, Java Community Process expressed nearly unanimous consensus on the proposed Module System scheme. [ 249 ]
The first Java 9 release candidate was released on August 9, 2017. [ 255 ] The first stable release of Java 9 was on September 21, 2017. [ 256 ]
At JavaOne 2011, Oracle discussed features they hoped to release for Java 9 in 2016. [ 257 ] Java 9 should include better support for multi-gigabyte heaps, better native code integration, a different default garbage collector ( G1 , for "shorter response times") [ 258 ] and a self-tuning JVM. [ 259 ] In early 2016, the release of Java 9 was rescheduled for March 2017 [ 260 ] and later again postponed four more months to July 2017. [ 261 ]
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OpenJDK 10 was released on March 20, 2018, with twelve new features confirmed. [ 267 ] Among these features were:
The first of these JEP 286 Local-Variable Type Inference , allows the var keyword to be used for local variables with the actual type calculated by the compiler. Due to this change, developers can do the following instead of manually specifying the variable's type:
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JDK 11 was released on September 25, 2018 and the version is currently open for bug fixes. It offers LTS, or Long-Term Support . Among others, Java 11 includes a number of new features, such as: [ 273 ]
A number of features from previous releases were dropped; in particular, Java applets and Java Web Start are no longer available. JavaFX , Java EE and CORBA modules have been removed from JDK. [ 274 ]
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JDK 12 was released on March 19, 2019. Among others, Java 12 includes a number of new features, such as: [ 321 ]
The preview feature JEP 325 extends the switch statement so it can also be used as an expression, and adds a new form of case label where the right hand side is an expression. No break statement is needed. For complex expressions a yield statement can be used. This becomes standard in Java SE 14.
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JDK 13 was released on September 17, 2019. Java 13 includes the following new features, as well as "hundreds of smaller enhancements and thousands of bug fixes". [ 327 ]
JEP 355 Text Blocks allows multiline string literals:
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JDK 14 was released on March 17, 2020. Java 14 includes the following new features, as well as "hundreds of smaller enhancements and thousands of bug fixes". [ 332 ]
JEP 305, Pattern Matching for instanceof simplifies the common case of an instanceof test being immediately followed by cast, replacing
with
JEP 359 Records allows easy creation of simple immutable Tuple -like classes. [ 333 ]
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JDK 15 was released on September 15, 2020. Java 15 adds e.g. support for multi-line string literals (aka Text Blocks). The Shenandoah and Z garbage collectors (latter sometimes abbreviated ZGC) are now ready for use in production (i.e. no longer marked experimental). Support for Oracle's Solaris operating system (and SPARC CPUs) is dropped (while still available in e.g. Java 11). The Nashorn JavaScript Engine is removed. Also removed some root CA certificates .
JEP 360 Sealed Classes adds sealed classes and interfaces that restrict which other classes or interfaces may extend or implement them. Only those classes specified in a permits clause may extend the class or interface.
Together with records, sealed classes are sum types . They work well with other recent features like records, switch expressions, and pattern matching for instance-of. They all form part of a system for "Pattern matching in Java" first discussed by Gavin Bierman and Brian Goetz , in September 2018. [ 339 ]
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JDK 16 was released on March 16, 2021. Java 16 removes Ahead-of-Time compilation (and Graal JIT ) options. [ 345 ] The Java implementation itself was and is still written in C++ , while as of Java 16, more recent C++14 (but still not e.g. C++17 or C++20 ) is allowed. The code was also moved to GitHub , dropping Mercurial as the source control system.
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JDK 17 was released in September 2021. [ 351 ] Java 17 is the 2nd long-term support (LTS) release since switching to the new 6-month release cadence (the first being Java 11).
JEP 406 extends the pattern matching syntax used in instanceof operations to switch statements and expressions. It allows cases to be selected based on the type of the argument, null cases and refining patterns
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JDK 18 was released on March 22, 2022. [ 381 ]
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JDK 19 was released on 20 September 2022. [ 390 ]
JEP 405 allows record patterns, extending the pattern matching capabilities of instanceof operators, and switch expressions, to include record patterns that explicitly refer to the components of the record.
Such patterns can include nested patterns, where the components of records are themselves records, allowing patterns to match more object graphs.
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Java 20 was released on 21 March 2023. [ 396 ] All JEPs were either incubators or previews.
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Java 21 was released on 19 September 2023. [ 402 ] The 32-bit version of Java for Windows on x86 was deprecated for removal with this release. The following JEPs were added, including eight JEPs that graduated from the incubating and preview stages, compared to Java 20 which only had previewing and incubating JEPs. Java 21 introduces features first previewed in Java 17 (pattern matching for switch statements ) and Java 19 (record patterns). All JEPs added with Java 21 include the following:
JEP 445, previewing unnamed classes, allows for a barebones Main class without boilerplate code:
instead of :
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Java 22 was released on March 19, 2024. [ 414 ] [ 415 ] The following features, or JEPs, were added with this release:
An API related to Java's threading implementation, java.lang.Thread.countStackFrames , was removed. [ 3 ] [ 416 ]
Java 23 was released on September 17, 2024, [ 417 ] [ 418 ] [ 419 ] with the following JEPs:
The String Templates preview feature was removed in Java 23 due to issues with the design of the feature. [ 420 ]
The specification for Java 24 was finalized in December 2024, with 24 JEPs making it into the release and it was released on 18 March 2025. [ 421 ]
The following JEPs were targeted to this version of Java SE: [ 422 ]
As of December 2024 [update] , the specification for Java 25 has not yet been finalized. Java 25 is scheduled for release in September 2025. [ 423 ]
The officially supported Java platform , first developed at Sun and now stewarded by Oracle, is Java SE . Releases are based on the OpenJDK project, a free and open-source project with an open development model . Other Java implementations exist, however—in part due to Java's early history as proprietary software . In contrast, some implementations were created to offer some benefits over the standard implementation, often the result of some area of academic or corporate-sponsored research. Many Linux distributions include builds of OpenJDK through the IcedTea project started by Red Hat , which provides a more straightforward build and integration environment.
Visual J++ and the Microsoft Java Virtual Machine were created as incompatible implementations. After the Sun v. Microsoft lawsuit, Microsoft abandoned it and began work on the .NET platform. In 2021, Microsoft started distributing compatible "Microsoft Build of OpenJDK" for Java 11 first then also for Java 17. Their builds support not only Windows, but also Linux and macOS .
Other proprietary Java implementations are available, such as Azul 's Zing. Azul offers certified open source OpenJDK builds under the Zulu moniker.
Prior to the release of OpenJDK, while Sun's implementation was still proprietary, the GNU Classpath project was created to provide a free and open-source implementation of the Java platform. Since the release of JDK 7, when OpenJDK became the official reference implementation, the original motivation for the GNU Classpath project almost completely disappeared, and its last release was in 2012.
The Apache Harmony project was started shortly before the release of OpenJDK. After Sun's initial source code release, the Harmony project continued, working to provide an implementation under a lax license , in contrast to the protective license chosen for OpenJDK. Google later developed Android and released it under a lax license. Android incorporated parts of the Harmony project, supplemented with Google's own Dalvik virtual machine and ART . Apache Harmony has since been retired, and Google has switched its Harmony components with equivalent ones from OpenJDK.
Both Jikes and Jikes RVM are open-source research projects that IBM developed.
Several other implementations exist that started as proprietary software but are now open source. IBM initially developed OpenJ9 as the proprietary J9 [ 424 ] but has since relicensed the project and donated it to the Eclipse Foundation . JRockit is a proprietary implementation that was acquired by Oracle and incorporated into subsequent OpenJDK versions. | https://en.wikipedia.org/wiki/Java_version_history |
Jay Hyung Lee ( Korean : 이재형) is a professor at Department of Chemical and Biomolecular Engineering in KAIST (Korea Advanced Institute of Science and Technology). His h-index is 55 according to Google Scholar . [ 2 ] Lee was a professor at Georgia Institute of Technology in the United States from 2000 to 2010. [ 3 ] Lee is a fellow of Institute of Electrical and Electronics Engineers (IEEE). [ 4 ] He is an editor of Computers & Chemical Engineering journal.
This article about a South Korean scientist is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Jay_H._Lee |
Jay Hambidge (1867–1924) was an American artist who formulated the theory of "dynamic symmetry", a system defining compositional rules, which was adopted by several notable American and Canadian artists in the early 20th century.
He was a pupil at the Art Students' League in New York and of William Merritt Chase , and a thorough student of classical art. He conceived the idea that the study of arithmetic with the aid of geometrical designs was the foundation of the proportion and symmetry in Greek architecture, sculpture and ceramics. [ 1 ] Careful examination and measurements of classical buildings in Greece , among them the Parthenon , the temple of Apollo at Bassæ , of Zeus at Olympia and Athenæ at Ægina , prompted him to formulate the theory of "dynamic symmetry" as demonstrated in his works Dynamic Symmetry: The Greek Vase (1920) [ 2 ] and The Elements of Dynamic Symmetry (1926). [ 3 ] It created a great deal of discussion. [ 1 ] He found a disciple in Dr. Lacey D. Caskey, the author of Geometry of Greek Vases (1922). [ 4 ]
In 1921, articles critical of Hambidge's theories were published by Edwin M. Blake in Art Bulletin , and by Rhys Carpenter in American Journal of Archaeology . Art historian Michael Quick says Blake and Carpenter "used different methods to expose the basic fallacy of Hambidge's use of his system on Greek art—that in its more complicated constructions, the system could describe any shape at all." [ 5 ] In 1979 Lee Malone said Hambidge's theories were discredited, but that they had appealed to many American artists in the early 20th century because "he was teaching precisely the things that certain artists wanted to hear, especially those who had blazed so brief a trail in observing the American scene and now found themselves displaced by the force of contemporary European trends." [ 4 ]
He was married to the American weaver Mary Crovatt . [ 6 ]
Dynamic symmetry is a proportioning system and natural design methodology described in Hambidge's books. The system uses dynamic rectangles , including root rectangles based on ratios such as √ 2 , √ 3 , √ 5 , the golden ratio (φ = 1.618...), its square root ( √ φ = 1.272...), and its square (φ 2 = 2.618....), and the silver ratio ( δ s = 2.414... {\displaystyle \delta _{s}=2.414...} ). [ 7 ] [ 8 ]
From the study of phyllotaxis and the related Fibonacci sequence (1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ...), Hambidge says that "a much closer representation would be obtained by a substitute series such as 118, 191, 309, 500, 809, 1309, 2118, 3427, 5545, 8972, 14517, etc. One term of this series divided into the other equals 1.6180, which is the ratio needed to explain the plant design system." [ 9 ] This substitute sequence is a generalization of the Fibonacci sequence that chooses 118 and 191 as the beginning numbers to generate the rest. In fact, the standard Fibonacci sequence provides the best possible rational approximations to the golden ratio for numbers of a given size. [ clarification needed ]
A number of notable American and Canadian artists have used dynamic symmetry in their painting, including George Bellows (1882–1925), [ 10 ] Maxfield Parrish (1870–1966), [ 11 ] The New Yorker cartoonist Helen Hokinson (1893–1949), Al Nestler (1900–1971), [ 12 ] [ 13 ] Kathleen Munn (1887–1974), [ 14 ] the children's book illustrator and author Robert McCloskey (1914–2003), [ 15 ] and Clay Wagstaff (b. 1964). [ 16 ] Elizabeth Whiteley has used dynamic symmetry for works on paper. [ 17 ]
The application and psychology of Dynamic Symmetry in such a fast and modern medium such as photography, in particular Digital Photography , is challenging but not impossible. The Rule of Thirds has been the composition of choice for a majority of new and experienced photographers alike. [ 18 ] Although this method is effective, Dynamic Symmetry can be applied to compositions to create a level of in depth creativity and control over the image. According to Bob Holmes, [ 19 ] a photographer from National Geographic, a photographer must "be responsible for everything in the frame". [ 20 ] Using diagonals to align subjects and the reciprocal diagonals associated to the size of the frame, one would be able to create a highly intricate work of fine art . For example, the portrait photographer Annie Leibovitz used this method to create an image, [ 21 ] among many others, for Vanity Fair Magazine . The image correctly posed each of the models to intersect the subject with a corresponding diagonal to draw the viewer to the main idea of the photograph.
This powerful process was used regularly by French painter turned film photographer: Henri Cartier-Bresson . Using Dynamic Symmetry, Henri was able to create engaging and interesting photographs that he deemed were made with the idea of "The Decisive Moment", [ 22 ] a photographic psychology that describes "when the visual and psychological elements of people in a real life scene to spontaneously and briefly come together in perfect resonance to express the essence of that situation". [ 23 ] | https://en.wikipedia.org/wiki/Jay_Hambidge |
Jay Quade (born December 13, 1955) is an American geochemist and geologist and former middle-distance runner . He is known for pioneering research applying geochemical isotopic methods for investigations of tectonics , global climate change , and the paleontology of Darwinian evolution. [ 1 ]
Jay Quade was born and grew up in Nevada. [ 2 ] As a teenager, he set two all-time Nevada State high school track and field records. At the University of New Mexico , he had a track scholarship, for four years. He was twice an NCAA All-American in track and once an NCAA champion in track (relay race). In 1977 he became a geologist employed by
the Mineral Exploration Division of Utah International, Inc. In 1978 he graduated with B.S. in geology from the University of New Mexico. In 1982 he graduated with an M.S. in geology from the University of Arizona. From 1982 to 1989 he worked as a geologist in Nevada — from 1982 to 1984 for Noranda Exploration, Inc. , from 1984 to 1986 for the Desert Research Institute , and from 1986 to 1989 for Mifflin & Associates (a mining consulting firm founded in 1986 by the geologist Martin David Mifflin). From 1989 to 1990 Quade was a graduate student at the University of Utah , where he received his Ph.D. in 1990. In 1991 he was a postdoc at the Australian National University . At the University of Arizona, he was appointed to an assistant professorship in 1992, an associate professorship in 1998, and a full professorship in 2003. [ 3 ]
Quade's research is remarkably varied, including low-temperature geochemistry, radiometric dating using a variety of isotopes, and theoretical reconstructions of paleoenvironments, mostly from the Cenozoic . [ 4 ] Some of his projects have involved archaeologists [ 5 ] and anthropologists. [ 6 ] Quade with Thure E. Cerling and other colleagues did important research on stable isotope composition of soil carbonate in the Great Basin . [ 1 ] In 2001, Quade with Nathan B. English, Julio L. Betancourt, and Jeffrey S. Dean published an important paper on the deforestation of Chaco Canyon . [ 7 ] [ 8 ] As a geological team member, Quade has done fieldwork on stratigraphy and paleohydrologic reconstruction in the western USA, gold deposits in Oregon, Alaska, and Nevada, and paleo-lake hydrology in Mongolia, Tibet, Chile, Argentina, and the western USA. From 1985 to 2015 his fieldwork on low temperature geochemistry has been done all over the world: parts of the US, Asia, Australia, and South America, as well as Greece and Ethiopia. [ 9 ]
In 2001 Quade won the Farouk El-Baz Award of the Geological Society of America (GSA). [ 10 ] In 2015 he was elected a Fellow of the Geological Society of American and also a Fellow of the American Geophysical Union (AGU). In 2017 he was elected a Fellow of the Geochemical Society . He received in 2016 a Lady Davis Fellowship from the Hebrew University and in 2017 a Japan Society for the Promotion of Science Fellowship from the University of Tokyo . [ 3 ] In 2018 he was awarded the Arthur L. Day Medal . [ 1 ]
In Nevada on December 21, 1984, Jay Quade married Barbra A. Valdez. They have three children. [ 3 ] | https://en.wikipedia.org/wiki/Jay_Quade |
Jean-Claude Bradley was a chemist who actively promoted Open Science in chemistry, [ 4 ] [ 5 ] including at the White House , [ 6 ] for which he was awarded the Blue Obelisk award in 2007. [ 1 ] [ 7 ] He coined the term " Open Notebook science ". He died in May 2014. [ 2 ] [ 8 ] A memorial symposium was held July 14, 2014 at Cambridge University, UK. [ 9 ]
One outcome of his Open Notebook work is the collection of physicochemical properties of organic compounds he was studying. All of this data he made available as Open data under the CCZero license. For example, in 2009 Bradley et al. published their work on making solubility data of organic compounds available as Open data. [ 10 ] Later, the melting point data set he collaborated on with Andrew Lang and Antony Williams was published with Figshare . [ 11 ] Both data sets were also made available as books via the Lulu.com self-publishing platform. [ 12 ] [ 13 ]
He blogged extensively and contributed to at least 25 individual blogs. [ 14 ] In an interview in 2008 with Bora Zivkovic titled "Doing Science Publicly", he spoke of his work and online presence. [ 15 ] In 2010, he gave an extensive interview about the impact of Open Notebook science with Richard Poynder. [ 16 ] | https://en.wikipedia.org/wiki/Jean-Claude_Bradley |
Jean-Claude Duplessy , born in 1942, is a French geochemist . He is Director of Research Emeritus at the CNRS [ 1 ] and a member of the French Academy of Sciences . [ 2 ]
Jean-Claude Duplessy, a former student of the Ecole Normale Supérieure (Ulm), a physics graduate, is a geochemist. His work has contributed to a better understanding of how the ocean has functioned over the recent history of the Earth. He is a recognized pioneer in rebuilding ocean dynamics through the use of carbon isotopes and foraminiferous shell oxygen in marine sediments. [ 3 ] [ 4 ] He was one of the first to see the importance of a high quality chronology for a reliable interpretation of measurements related to climate variations in the Earth's past.
He began his research just as the foundations of isotopic geochemistry were beginning to be well established through the work of Harold Urey and Cesare Emiliani in Chicago. The analysis of stable isotopes and natural radioactive elements makes it possible to approach the study of major biogeochemical cycles in an original way and to reconstruct changes in the Earth's climate and environment by applying current principles. [ 5 ]
Jean-Claude Duplessy initially focused on the concretions of the caves and demonstrated that they were good recorders of the hydrological cycle and air temperature at the time they were formed. He obtained the first reconstructions of air temperatures and climatic conditions in the south of France for the last millennia and for the previous interglacial period [ 6 ] Recently, this type of study has been resumed in Europe due to the development of new dating methods and the study of stalagmites seems open to a great future.
Duplessy turned to the ocean because of its role as a climate regulator and its major impact on biogeochemical cycles, particularly the carbon cycle . His doctoral thesis work has focused on the geochemistry of stable carbon isotopes in the sea. [ 7 ] He showed how the distribution of the stable heavy carbon isotope, carbon-13 , was governed by biological fractionations related to chlorophyll assimilation by phytoplankton , then by ocean circulation and finally, to a lesser extent, by gas exchanges between the ocean and the atmosphere. All these phenomena, which dominate the carbon cycle in the ocean, are now being taken into account to study the fate of carbon dioxide emitted by human activities.
Duplessy led numerous oceanographic campaigns and showed that variations in the isotopic composition of fossil foraminifera present in the sediments of the various oceans made it possible to reconstruct changes in the isotopic composition of the ocean and ocean circulation on a large scale, which opened a new scientific field, paleo-oceanography . [ 8 ] This has grown to the point where there is now an international journal devoted to this discipline, of which he was one of the first associate editors.
He established the first reconstructions of the deep ocean circulation during the height of the last ice age and during the last interglacial period . This has led him to highlight a disruption in the functioning of the ocean: the North Atlantic deep water disappears under glacial conditions, accompanied by a general slowdown in large-scale ocean circulation, the intensity of the Gulf Stream and the heat flux transported by the Atlantic Ocean to the coasts of Western Europe . [ 9 ]
The deep waters of the world ocean are formed by convection and diving of dense surface waters during winter periods. To understand the causes of changes in deep ocean circulation, it was necessary to develop a method to reconstruct not only the temperature (which was already known), but also the salinity of surface waters in the past. Duplessy has developed a method based on fractionations that affect stable oxygen isotopes during the water cycle. This has allowed him to reconstruct the salinity of the Atlantic Ocean during the last glacial maximum with sufficient accuracy for major modelling groups to use this data to simulate global ocean circulation using general ocean circulation models. [ 10 ] These results have provided the basis for understanding ocean circulation in glacial climates and the role that the ocean can play in disrupting climate, as outlined in a book written for the general public entitled "When the ocean gets angry ". [ 11 ] [ 12 ] He is also the co-author of "Gros temps sur la planète ", [ 13 ] [ 14 ] "Paléoclimatologie : Tome 1, [ 15 ] [ 16 ] and Tome 2 "Paléoclimatologie : Tome 2, Emboiter les pièces du puzzle : comprendre et modéliser un système complexe ". [ 17 ] [ 18 ]
Chronology plays an essential role in understanding the evolution of climates and the links with astronomical theory initiated by Dr. Milankovitch and developed by André Berger in Louvain-La-Neuve and John Imbrie at Brown University . Duplessy launched the first accelerator mass spectrometry laboratory, one of the objectives of which is the fine measurement of carbon-14 to date marine sediments. [ 19 ] With his collaborators, he was able to provide the first evidence of a ten-degree change in seawater temperature in times compatible with human life. These results were confirmed and further refined by the study of drilling in Greenland ice. Today, rapid climatic variations are recognized as a major feature of climate change. [ 20 ]
While developing this research and a group of marine paleoclimatology, he has endeavoured to bring to light in France the study of biogeochemical cycles within the surface envelopes of our planet. With the support of the CNRS, he launched the program to study the flow of matter in the ocean. This programme would bring together the actions of biologists, chemists and geochemists by highlighting the fundamental role of the coupling between biology and geochemistry, which led to the now recognized notion of biogeochemistry . This effort led the French teams to initiate, with their American and European colleagues, the International Joint Global Ocean Flux Study program to quantify carbon fluxes in the ocean and the role of plankton-produced particulate matter transfer in supplying the deep ocean environment with carbon, food and energy. [ 21 ]
By the late 1980s, it had become clear that understanding living conditions on the Earth's surface required studying the couplings between the geosphere and living things. At the request of COFUSI (Comité français des unions scientifiques internationales), [ 22 ] Duplessy chaired the French scientific committee of the International Geosphere-Biosphere Programme. He federated research on the physical, chemical and biological mechanisms that govern the evolution of our environment. This research program initiated the study of the variability of the coupled geosphere-biosphere system, giving high priority to palaeoclimatic and palaeo-environmental reconstructions over geological time. These studies have thus made it possible to highlight phenomena as unexpected as the great variability of the carbon cycle in relation to changes in vegetation. These themes will become increasingly important in the coming years in the study of human-induced climate change, as the future evolution of greenhouse gas concentrations can only be realistically simulated if the interactions between the biosphere and biogeochemical cycles are well understood, so that they can be taken into account in models simulating the behaviour of the "Earth" system. The last interglacial period of 120,000 years, often taken as an analogue of a significantly warmer climate than today, reflects major changes in global ocean temperature and circulation that have contributed to destabilizing the West Antarctic ice cap. [ 23 ] | https://en.wikipedia.org/wiki/Jean-Claude_Duplessy |
Jean-Joseph Kapeller (24 July 1706 – 29 November 1790) was a French painter, architect and geometer . [ 1 ] Born in Marseille he was influenced by Jean-Baptiste de La Rose and Joseph Vernet , mainly producing landscapes and seascapes such as his 1756 masterwork Embarcation of the Expeditionary Corps for Minorca at the Port of Marseille under the command of the Duke of Richelieu . He and his contemporary Charles François Lacroix de Marseille produced seascapes which marked a step-change in the appreciation of seascapes in Provence in the second half of the 18th century. [ 2 ]
Kapeller and Michel-François Dandré-Bardon co-founded Marseille's Académie de peinture et de sculpture, with Kapeller becoming its director-rector in 1771 and giving classes in drawing and gemotery there which were attended by his main pupil Henry d'Arles . Kapeller was also a major figure in freemasonry in the city, becoming grand master of the Chevaliers de l'Orient lodge. He also became rector of the third order Franciscans at the Récollets in 1745 and a member of a chapel of penitents. Famous in Marseille in his own time, he seems to have never become much known outside Provence and most of his works are now lost, though some now hang in public collections in Toulon and Marseille.
His father Jean-Georges had been born in Meilen, Zurich and married Marie-Anne Daignan in Marseille on 11 January 1701, the year before Jean-Joseph's birth. [ A 1 ] Jean-Georges was also a painter and seems to have been highly regarded by contemporary art critics, who referred to "the ardour of his zeal for everything which concerned the school, artists and matters of art". [ 3 ] Jean-Georges died before 1723, possibly during the bout of plague which affected Marseille in 1723, according to Joseph Billioud .
Jean-Joseph Kapeller married Anne-Marie Mouren on 24 January 1723 in the collegiate church of Saint-Martin. [ A 2 ] The couple had two children, Marie-Eugénie (called "widow Mullard" in Jean-Joseph's will of 1778 [ A 3 ] ) and Pierre-Paul (a painter and teacher who was made an associate of the Académie in 1753 and settled in the Spanish colonies in South America, specialising in still lives of shellfish [ 4 ] and exhibiting at the Académie de peinture in 1757).
Kapeller's knowledge of architecture caused the Académie's permanent director Dandré-Bardon to make him its permanent professor of geometry, teaching classes which comprised "elementary geometry, transcendental geometery and sublime geometry which applied differential calculus , principally integral calculus to the knowledge of curves and surfaces". [ 5 ] These classes were compulsory for all the Académie's pupils, including the future seascape painter Antoine Roux (1765 - 1835), since such knowledge was just as necessary to painters and sculptors as to astronomers and architects. These classes constituted an initial training in the field, which Kapeller also running a secondary course in the orders of architecture. Only after taking these preparatory classes could pupils move on to drawing the head and ornamentation.
Kapeller was lastly professor of "mechanics" (what is now known as orthography ) according to the terms in the Académie's lists. [ 6 ] The previous years' issues of the Almanach historique de Marseille by Grosson showed that Kappeler already ran a "school of mathematics, drawing and of civilian and military architecture" in his home on rue d'Aubagne. [ A 4 ]
According to professor Régis Bertrand, Kapeller seems to have retained his roles at the Académie until 1787 : an octogenarian, he was thus replaced by architect Jacques Dageville (1723–1794). [ A 5 ]
In Marseille he combined his roles at the Académie with that of police commissioner (a purely honorary and unpaid role) for 16 years. [ 7 ] | https://en.wikipedia.org/wiki/Jean-Joseph_Kapeller |
Jean-Louis Loday (12 January 1946 – 6 June 2012) was a French mathematician who worked on cyclic homology and who introduced Leibniz algebras (sometimes called Loday algebras) and Zinbiel algebras . [ 1 ] He occasionally used the pseudonym Guillaume William Zinbiel , formed by reversing the last name of Gottfried Wilhelm Leibniz .
Loday studied at Lycée Louis-le-Grand and at École Normale Supérieure in Paris . He completed his Ph.D. at the University of Strasbourg in 1975 under the supervision of Max Karoubi , with a dissertation titled K-Théorie algébrique et représentations de groupes . He went on to become a senior scientist at CNRS and a member of the Institute for Advanced Mathematical Research (IRMA) at the University of Strasbourg. | https://en.wikipedia.org/wiki/Jean-Louis_Loday |
Jean-Marie Tarascon FRSC (born September 21, 1953) is professor of chemistry at the Collège de France in Paris and director of the French Research Network on Electrochemical Energy Storage (RS2E). [ 14 ] [ 15 ] [ 16 ] [ 17 ]
Tarascon was educated at the University of Bordeaux , where he was awarded a Diplôme d'études universitaires générales in physics and chemistry , a Master of Science degree in chemical engineering , and a PhD in solid-state chemistry in 1981. [ 13 ] [ 1 ]
Following his PhD, Tarascon did postdoctoral research at Cornell University . [ 12 ] He worked at Bell Labs [ 9 ] [ 10 ] and Bellcore [ 11 ] from 1982 to 1994, then moved to the University of Picardie Jules Verne in 1994. He has been at the College de France since 2010. He is also credited with laying foundations of the reputable Erasmus mundus masters course in energy storage and conversion "Materials for energy storage and conversion" hosted by UPJV, Amiens in association with seven universities across the globe and several energy research networks.
Tarascon's research [ 18 ] investigates the synthesis of novel electronic phenomena and materials such as superconductors , ferroelectrics , fluoride glasses , rechargeable batteries [ 19 ] and colossal magnetoresistance . [ 20 ] He has made many contributions to superconductivity and was the original proponent of the thin and flexible plastic lithium ion battery . [ 21 ] [ 22 ] [ 23 ]
Tarascon was elected a Foreign Member of the Royal Society (ForMemRS) in 2014. His nomination reads: [ 2 ]
Jean-Marie Tarascon is distinguished for his outstanding leadership in the materials chemistry of energy conversion and storage devices and for seminal studies of high temperature superconductors . His pioneering work on electrode reaction processes that can store more energy than those in conventional lithium-ion batteries , his work on molecular electrodes and his realization of the plastic battery, have changed thinking in the field.
Tarascon was honoured by the New Jersey Inventors Hall of Fame in 2002. [ 24 ] He was nominated to the Académie des Sciences in 2005, and was the University of Picardie Jules Verne (UPJV) gold medalist in 2008. [ 25 ] He won the ENI Protection of the Environment award in 2011. [ 1 ] In 2015 he was awarded the Royal Society of Chemistry 's Centenary Prize . [ 26 ] In 2016, he received an honorary doctorate ' doctor honoris causa ' from Hasselt University . [ 27 ] In 2017, he was one of the two winners of the Eric and Sheila Samson Prime Minister's Prize for Innovation in Alternative Fuels for Transportation. [ 28 ] He was one of the five nominated for the CNRS Innovation Medals. [ 29 ] In 2020 he received the Balzan Prize for Environmental Challenges: Materials Science for Renewable Energy. [ 30 ] | https://en.wikipedia.org/wiki/Jean-Marie_Tarascon |
Jean-Michel Emmanuel Salanskis (born 5 April 1951 in Paris) is a French philosopher and mathematician , professor of science and philosophy at the University of Paris X Nanterre .
Originally gaining a Diplôme d'études approfondies in pure mathematics , he went on to study philosophy with Luis Puig and Jean-Francois Lyotard from 1974 to 1983. In 1986 he completed a doctoral dissertation on Le continu et le discret (the continuous and the discrete).
He is an important interpreter of continental philosophers such as Jacques Derrida , Emmanuel Levinas , Edmund Husserl , Martin Heidegger , [ 1 ] and Gilles Deleuze , and he has published widely in English and French. He has also written about Judaism and the philosophy of mathematics . [ 2 ] [ 3 ]
In his book La gauche et l'égalité he argues that the left is structured by a “critique of power taking the form of a critique of man’s humiliation at the hands of transcendence" (p. 22), and that it is therefore necessary "to eliminate entirely the communist episode from the left,” for this episode partakes of the crushing of the people by one man who can “become the keystone of the world, restoring the attributes and the aura of royalty" (p. 37). [ 4 ]
In his 2010 book Derrida , he presents the philosophy of Jacques Derrida in an accessible manner for the lay reader, showing how Derrida's work related to the fields of psychoanalysis, radical politics, and literature. [ 5 ]
In Les temps du sens he embarks on a project to devise a mathematical hermeneutics that can be applied to fields such as philosophy of science , cognitive sciences and philosophy of religion . [ 6 ] | https://en.wikipedia.org/wiki/Jean-Michel_Salanskis |
Jean-Pierre Serre ( French: [sɛʁ] ; born 15 September 1926) is a French mathematician who has made contributions to algebraic topology , algebraic geometry and algebraic number theory . He was awarded the Fields Medal in 1954, the Wolf Prize in 2000 and the inaugural Abel Prize in 2003.
Born in Bages , Pyrénées-Orientales , to pharmacist parents, Serre was educated at the Lycée de Nîmes. Then he studied at the École Normale Supérieure in Paris from 1945 to 1948. [ 1 ] He was awarded his doctorate from the Sorbonne in 1951. From 1948 to 1954 he held positions at the Centre National de la Recherche Scientifique in Paris . In 1956 he was elected professor at the Collège de France , a position he held until his retirement in 1994.
His wife, Professor Josiane Heulot-Serre, was a chemist; she also was the director of the Ecole Normale Supérieure de Jeunes Filles. Their daughter is the former French diplomat, historian and writer Claudine Monteil . The French mathematician Denis Serre is his nephew. He practices skiing, table tennis, and rock climbing (in Fontainebleau ).
From a very young age he was an outstanding figure in the school of Henri Cartan , [ 2 ] working on algebraic topology , several complex variables and then commutative algebra and algebraic geometry , where he introduced sheaf theory and homological algebra techniques. Serre's thesis concerned the Leray–Serre spectral sequence associated to a fibration . Together with Cartan, Serre established the technique of using Eilenberg–MacLane spaces for computing homotopy groups of spheres , which at that time was one of the major problems in topology.
In his speech at the Fields Medal award ceremony in 1954, Hermann Weyl gave high praise to Serre, and also made the point that the award was for the first time awarded to a non-analyst. Serre subsequently changed his research focus.
In the 1950s and 1960s, a fruitful collaboration between Serre and the two-years-younger Alexander Grothendieck led to important foundational work, much of it motivated by the Weil conjectures . Two major foundational papers by Serre were Faisceaux Algébriques Cohérents (FAC, 1955), [ 3 ] on coherent cohomology , and Géométrie Algébrique et Géométrie Analytique ( GAGA , 1956). [ 4 ]
Even at an early stage in his work Serre had perceived a need to construct more general and refined cohomology theories to tackle the Weil conjectures. The problem was that the cohomology of a coherent sheaf over a finite field could not capture as much topology as singular cohomology with integer coefficients. Amongst Serre's early candidate theories of 1954–55 was one based on Witt vector coefficients.
Around 1958 Serre suggested that isotrivial principal bundles on algebraic varieties – those that become trivial after pullback by a finite étale map – are important. This acted as one important source of inspiration for Grothendieck to develop the étale topology and the corresponding theory of étale cohomology . [ 5 ] These tools, developed in full by Grothendieck and collaborators in Séminaire de géométrie algébrique (SGA) 4 and SGA 5, provided the tools for the eventual proof of the Weil conjectures by Pierre Deligne .
From 1959 onward Serre's interests turned towards group theory , number theory , in particular Galois representations and modular forms .
Amongst his most original contributions were: his " Conjecture II " (still open) on Galois cohomology; his use of group actions on trees (with Hyman Bass ); the Borel–Serre compactification; results on the number of points of curves over finite fields; Galois representations in ℓ-adic cohomology and the proof that these representations have often a "large" image; the concept of p-adic modular form ; and the Serre conjecture (now a theorem) on mod- p representations that made Fermat's Last Theorem a connected part of mainstream arithmetic geometry .
In his paper FAC, [ 3 ] Serre asked whether a finitely generated projective module over a polynomial ring is free . This question led to a great deal of activity in commutative algebra , and was finally answered in the affirmative by Daniel Quillen and Andrei Suslin independently in 1976. This result is now known as the Quillen–Suslin theorem .
Serre, at twenty-seven in 1954, was and still is the youngest person ever to have been awarded the Fields Medal . He went on to win the Balzan Prize in 1985, the Steele Prize in 1995, the Wolf Prize in Mathematics in 2000, and was the first recipient of the Abel Prize in 2003. He has been awarded other prizes, such as the Gold Medal of the French National Scientific Research Centre (Centre National de la Recherche Scientifique, CNRS).
He is a foreign member of several scientific Academies (US, Norway, Sweden, Russia, the Royal Society, Royal Netherlands Academy of Arts and Sciences (1978), [ 6 ] American Academy of Arts and Sciences , [ 7 ] National Academy of Sciences , [ 8 ] the American Philosophical Society [ 9 ] ) and has received many honorary degrees (from Cambridge, Oxford, Harvard, Oslo and others). In 2012 he became a fellow of the American Mathematical Society . [ 10 ]
Serre has been awarded the highest honors in France as Grand Cross of the Legion of Honour (Grand Croix de la Légion d'Honneur) and Grand Cross of the Legion of Merit (Grand Croix de l'Ordre National du Mérite).
A list of corrections , and updating, of these books can be found on his home page at Collège de France. | https://en.wikipedia.org/wiki/Jean-Pierre_Serre |
Jean-Raymond Abrial (born 6 November 1938) [ 1 ] is a French computer scientist and inventor of the Z and B formal methods . [ 2 ]
Abrial was a student at the École Polytechnique (class of 1958).
Abrial's 1974 paper Data Semantics [ 3 ] laid the foundation for a formal approach to Data Models ; although not adopted directly by practitioners, it directly influenced all subsequent models from the Entity-Relationship Model through to RDF .
J.-R. Abrial is the father of the Z notation (typically used for formal specification of software), during his time at the Programming Research Group under Prof. Tony Hoare within the Oxford University Computing Laboratory (now Oxford University Department of Computer Science ), arriving in 1979 and sharing an office and collaborating with Cliff Jones . [ 4 ] He later initiated the B-Method , with better tool-based software development support for refinement from a high-level specification to an executable program , including the Rodin tool . These are two important formal methods approaches for software engineering . He is the author of The B-Book: Assigning Programs to Meanings . [ 5 ] For much of his career he has been an independent consultant. [ 6 ] He was an invited professor at ETH Zurich from 2004 to 2009. [ 7 ]
Abrial was elected to be a Member of the Academia Europaea in 2006. [ 6 ]
This article about a French computer specialist is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Jean-Raymond_Abrial |
Jean Cavaillès ( / k ɑː v aɪ ˈ ɛ s / ; French: [ʒɑ̃ kavajɛs] ; 15 May 1903 – 4 April 1944) was a French philosopher and logician who specialized in philosophy of mathematics and philosophy of science . He took part in the French Resistance within the Libération movement and was arrested by the Gestapo on 17 February 1944 and shot on 4 April 1944.
Cavaillès was born in Saint-Maixent , Deux-Sèvres . After passing his first baccalauréat in 1919 and baccalauréats in mathematics and philosophy the following year, he studied at the Lycée Louis-le-Grand , including two years of classes préparatoires , before entering the École Normale Supérieure in 1923, reading philosophy. In 1927 he passed the agrégation competitive exam. He began graduate studies in Philosophy in 1928 under the supervision of Léon Brunschvicg . Cavaillès won a Rockefeller Foundation scholarship in 1929–1930. In 1931 he travelled extensively in Germany; in Göttingen he conceived, jointly with Emmy Noether , the project of publishing the Cantor - Dedekind correspondence. He was a teaching assistant at the École Normale Supérieure between 1929 and 1935, then teacher at the lycée d'Amiens (now lycée Louis-Thuillier ) in 1936. In 1937, he successfully defended his doctoral theses [ 3 ] at the University of Paris and became a Doctor of Letters in Philosophy. He was then appointed maître de conférences in Logic and in General Philosophy at the University of Strasbourg .
After the outbreak of World War II, he was mobilized in 1939 as an infantry lieutenant with the 43rd Regiment and was later attached to the Staff of the 4th Colonial Division . He was honoured for bravery twice and was captured on 11 June 1940. At the end of July 1940 he escaped from Belgium and fled to Clermont-Ferrand , where the university of Strasbourg was re-organized.
At the end of December 1940, he met Emmanuel d'Astier de la Vigerie with whom he created a small group of resistance fighters, known as "the Last Column". To reach a broader audience, they created a newspaper which was to become Libération . It served as the mouthpiece of both Libération-Sud and Libération-Nord . Cavaillès took an active part in editing the paper. The first edition appeared in July 1941.
In 1941, he was appointed professor at the Sorbonne and left Clermont-Ferrand for Paris , where he helped form the Libération-Nord resistance group, becoming part of its management committee.
In April 1942, at the instigation of Christian Pineau , the central Office of Information and Action ( BCRA ) of London charged him with the task of forming an intelligence network in the Northern Zone, known as "Cohors". He was ordered by Christian Pineau to pass into the Southern Zone, and Cavaillès headed the network and formed similar groups in Belgium and the north of France.
In September 1942 he was arrested with Pineau in Narbonne by the French police . After a failed escape attempt to London, he was interned in Montpellier at the Saint-Paul d' Eyjeaux prison camp from where he escaped at the end of December 1942. The book Cavaillès wrote in prison in Montpellier in 1942 was published posthumously in 1946, edited by the epistemologist Georges Canguilhem and the mathematician Charles Ehresmann under the title Sur la logique et la theorie de la science .
Denounced as a public enemy by the Vichy regime and sought by the police, he fled clandestinely to London in February 1943. There he met General Charles de Gaulle on several occasions.
Back in France on 15 April he resigned from the management Committee of the Libération movement in order to dedicate himself entirely to direct action. He was in charge of the sabotage of the stores of the Kriegsmarine in Brittany and German radio installations on the coast.
Betrayed by one of his liaison officers [ who? ] , he was arrested on 28 August 1943 in Paris with his sister [ who? ] and her brother-in-law [ who? ] . Tortured, imprisoned in Fresnes then in Compiègne , he was transferred to the Citadel from Arras and was reported as being executed there on 17 February 1944. New research in 2015 revealed this date was incorrect and he was sentenced and executed on 4 April 1944. [ 4 ] Buried at first in Arras under a wooden cross marked "unknown n°5", his body was exhumed in 1946 to be buried in the Crypt in the Sorbonne , in Paris.
The Centre Cavaillès de l' École Normale Supérieure was established in Paris in 1969, at 29 rue d'Ulm , as Centre for the Study of the History and Philosophy of Science. At the formal opening, philosopher Georges Canguilhem said, "A philosopher-mathematician loaded with explosives, lucid and reckless, resolute without optimism. If that's not a hero, what is a hero?" (Translated from the original French language : "Un philosophe mathématicien bourré d'explosifs, un lucide téméraire, un résolu sans optimisme. Si ce n'est pas un héros, qu'est-ce qu'un héros ?") [ 5 ]
Cavaillès is honored in the Heroes of the Resistance postage stamp set.
In L'Armée des ombres , a 1969 film directed by Jean-Pierre Melville , the character of Luc Jardie (the Chief) was in part inspired by Cavaillès. Jardie's chief operative, recuperating from injuries in a hideaway, has only five books; the title of each is a publication of Cavaillès, though the author is shown as "Luc Jardie."
English translations | https://en.wikipedia.org/wiki/Jean_Cavaillès |
Jean M.J. Fréchet (born August 1944) is a French-American chemist and professor emeritus at the University of California, Berkeley . He is best known for his work on polymers including polymer-supported chemistry, chemically amplified photoresists, dendrimers, macroporous separation media, and polymers for therapeutics. He has authored nearly 900 scientific paper and 200 patents including 96 US patents. [ 2 ] His research areas include organic synthesis and polymer chemistry applied to nanoscience and nanotechnology with emphasis on the design, fundamental understanding, synthesis, and applications of functional macromolecules .
Fréchet is an elected fellow of the American Association for the Advancement of Science , the American Chemical Society , and the American Academy of Arts and Sciences , and an elected member of the US National Academy of Sciences , the US National Academy of Engineering , and the Academy of Europe ( Academia Europaea ).
Fréchet received his first university degree at the Institut de Chimie et Physique Industrielles (now CPE) in Lyon, France, before coming to the US for studies in organic and polymer chemistry under Conrad Schuerch at the State University of New York College of Environmental Science and Forestry, and at Syracuse University (Ph.D. 1971). He was on the Chemistry Faculty at the University of Ottawa in Canada from 1973 to 1987, when he became the IBM Professor of Polymer Chemistry at Cornell University. In 1997 Fréchet joined Chemistry faculty at the University of California, Berkeley and was named the Henry Rapoport Chair of Organic Chemistry in 2003 and Professor of Chemical and Biological Engineering in 2005. From 2010 to 2019 he served as the first Vice President for Research, then Senior Vice-President for Research, Innovation, and Economic Development at the King Abdullah University of Science and Technology. [ citation needed ]
Fréchet’s early work focused on polymer-supported chemistry with the first approach to the solid-phase synthesis of oligosaccharides [ 3 ] and pioneering work on polymeric reagents and polymer protecting groups. [ 4 ] In 1979 Working with C.G. Willson at IBM during a sabbatical leave, he invented chemically amplified photoresists [ 5 ] [ 6 ] for micro and nanofabrication. This widely used patented technology [ 7 ] which enables the extreme miniaturization of microelectronic devices is now ubiquitous for the fabrication of the very powerful computing and communication equipment in worldwide use. The addition of photogenerated bases [ 8 ] led to additional advances in chemically amplified resists. In 1990 working with Craig Hawker at Cornell, he developed the convergent synthesis of dendrimers [ 9 ] as well as approaches to hyperbranched polymers. [ 10 ] In 1992, working with F. Svec at Cornell, he reported the first preparation of macroporous polymer monoliths [ 11 ] that are now used in a variety of chemical separations. Later work at Berkeley saw the development of polymers and dendrimers as carriers for targeted therapeutics [ 12 ] and successful approaches to new organic materials for transistors and solar cells. [ 13 ] | https://en.wikipedia.org/wiki/Jean_Fréchet |
Jean Lynch-Stieglitz is a paleoceanographer known for her research on reconstructing changes in ocean circulation over the last 100,000 years.
An interest in the natural world, combined with the logic of science and math, attracted Lynch-Stieglitz to science and after a summer at the Duke University Marine Laboratory she decided on a career in physical oceanography. [ 1 ] In 1986, she earned B.S. degrees in physics and geology from Duke University [ 2 ] and for two years she worked as an oceanographer at the Pacific Marine Environmental Laboratory . From 1988 until 1989 she worked at the Maryland Science Center and as a programmer at Johns Hopkins University before moving to Columbia University where she earned an M.A. (1991) and Ph.D. (1995) in geological sciences. [ 3 ] After two years as a postdoctoral scholar at Woods Hole Oceanographic Institution , in 1996 she returned to New York where she joined the faculty of the Lamont–Doherty Earth Observatory . In 2004, Lynch-Stieglitz moved to the Georgia Institute of Technology where she was promoted to professor in 2010. [ 3 ]
From 2012 to 2015, Lynch-Stieglitz was the Editor of Earth and Planetary Science Letters . [ 4 ]
In 2015 Lynch-Stieglitz was elected a fellow of the American Association for the Advancement of Science "for bringing physical oceanography approaches to the study of transient circulation changes during ice ages, providing a window into the ocean’s interaction with today’s climate change." [ 5 ]
Lynch-Stieglitz's research links the ocean and climate over the past 100,000 years. She has used carbon isotopes in benthic foraminifera to reconstruct air-sea exchange in carbon isotopes, [ 6 ] changes in the movement of deep water masses, [ 7 ] and Antarctic Intermediate Water in the transitions between glacial and interglacial periods. [ 8 ] In the Atlantic Ocean, she has examined movement of the Gulf Stream during the Last Glacial Maximum [ 9 ] and linked changes in the Atlantic meridional overturning circulation and to rapid changes in climate. [ 10 ] [ 11 ] [ 12 ] Her research also extends to regions where ice alters the exchange of carbon dioxide between atmosphere and ocean in glacial periods, [ 13 ] and work in the Pacific Ocean where she has examined sea surface temperatures from the Last Glacial Maximum to the present. [ 14 ] | https://en.wikipedia.org/wiki/Jean_Lynch-Stieglitz |
Jean Marcel Rouxel (February 24, 1935 in Malestroit – March 19, 1998 in Nantes ) was a French synthetic chemist known for his work in solid state synthesis of low-dimensional materials. [ 1 ] [ 2 ] [ 3 ] He pioneered the use of solid precursors in soft chemistry . [ 4 ] [ 5 ]
Rouxel studied at the University of Rennes and the University of Bordeaux , where he received his PhD in 1961 under Paul Hagenmuller on two classes of aluminum compounds. After that he was an assistant in Bordeaux and after military service in Algeria between 1962 and 1963, he went to the newly founded laboratory for solid state chemistry (today named after him) at the University of Nantes . There he became an assistant professor in 1964 and a professor in 1968. From 1986 to 1998 he was scientific advisor at Rhône-Poulenc . In 1988 he became director of the Institute for Materials (Institut des Matériaux, which arose from the Institute for Solid State Chemistry) in Nantes, which he remained until his death in 1998. From 1991 to 1996, he was a professor at the Institut Universitaire de France . From 1994 to 1995, he was a professor at the École normale supérieure de Lyon and from 1997 until his death he was a professor of solid state chemistry at the Collège de France . [ 1 ]
He synthesized and characterized numerous solids in low dimensions (that is, one or two dimensions) and explored the properties of one-dimensional inorganic chains, such as the phase transition to charge density waves. Another area of research was incommensurable structures in solids and the connection between chemistry and electronic band structure in solids. He studied the mechanisms of anionic polymerization in solids and the competition of anions and cations in redox reactions in solids. He is also working on a type of synthesis based on biological processes, which is called soft chemistry ( chimie douce in French), after a word coined by the French chemist Jacques Livage in 1977. [ 1 ] [ 5 ]
In 1974 he received the CNRS Silver Medal and in 1997 the CNRS Gold Medal and the Prix Paul Pascal from the French Academy of Sciences . In 1992 he was awarded the Gay-Lussac Humboldt Prize . Rouxel received the Alexander von Humboldt Research Award (1993) and gave the Debye Lecture of the Cornell University section of the American Chemical Society . He was Knight of the Legion of Honor (1988, officer from 1997) and officer of the Ordre national du Mérite and commander of the Palmes académiques . In 1988 he became a member of the Académie des sciences and he was a member of the American Academy of Arts and Sciences (1992), the Academia Europaea , the German National Academy of Sciences Leopoldina (1997) and the Indian Academy of Sciences . [ 6 ] [ 3 ]
Rouxel had two sons and three daughters with his wife Yannick. He died from ruptured aneurysm . [ 3 ] | https://en.wikipedia.org/wiki/Jean_Rouxel |
Jean Weissenbach (born 13 February 1946) is a French biologist. He is the current director of the Genoscope . He is one of the pioneers of sequencing and genome analysis. [ 1 ]
This article about a French biologist is a stub . You can help Wikipedia by expanding it .
This article about a geneticist or evolutionary biologist is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Jean_Weissenbach |
Jean Louis Maxime van Heijenoort ( / v æ n ˈ h aɪ . ə n ɔːr t / van HY -ə-nort ; French: [ʒɑ̃ lwi maksim van‿ɛjɛnɔʁt] ; Dutch: [vɑn ˈɦɛiənoːrt] ; July 23, 1912 – March 29, 1986) was a historian of mathematical logic . He was also a personal secretary to Leon Trotsky from 1932 to 1939, and an American Trotskyist until 1947.
Van Heijenoort was born in Creil , France. His parents had immigrated from the Netherlands before his birth. When van Heijenoort was only two years old, his father passed away, leaving his family in financial hardship. Despite these challenges, he pursued his education and became proficient in French. Throughout his life, he maintained strong connections with his extended family and friends in France, making biannual visits after he obtained American citizenship in 1958.
In 1932, van Heijenoort was recruited by Yvan Craipeau to join the Trotskyist movement. He joined the Communist League in the same year. After Trotsky was exiled, he hired van Heijenoort as a secretary and bodyguard, primarily because of his fluency in French, Russian , German, and English. Van Heijenoort spent seven years in Trotsky's household, during which he served as a translator, helped Trotsky write several books and carried on an extensive intellectual and political correspondence in several languages.
In 1939, van Heijenoort moved to New York City to be with his second wife, Beatrice "Bunny" Guyer. He was not involved in the circumstances leading to Trotsky's murder in 1940. In New York , he worked for the Socialist Workers Party (US) (SWP) and wrote a number of articles for the American Trotskyist press and other radical outlets. He was elected to the secretariat of the Fourth International in 1940 but resigned when Felix Morrow and Albert Goldman , with whom he had sided, were expelled from the SWP. (Goldman subsequently joined the US Workers Party while Morrow did not join any other party or grouping.) In 1947, van Heijenoort too was expelled from the SWP. In 1948, he published an article, entitled "A Century's Balance Sheet", in which he criticized that part of Marxism which saw the "proletariat" as the revolutionary class. He continued to hold other parts of Marxism as true.
Van Heijenoort was spared the ordeal of McCarthyism as everything he published in Trotskyist publications appeared under one of over a dozen pen names he used. According to Feferman (1993), Van Heijenoort the logician was quite reserved about his Trotskyist youth, and did not discuss politics. Nevertheless, he contributed to the Trotskyist movement until the last decade of his life, when he wrote his monograph With Trotsky in Exile (1978), and an edition of Trotsky's correspondence (1980). He advised and collaborated with the archivists at the Houghton Library in Harvard University , which holds many of Trotsky's papers from his years in exile.
After completing a Ph.D. in mathematics at New York University in 1949 under the supervision of J. J. Stoker , Van Heijenoort began to teach mathematics at New York University, but moved to logic and philosophy of mathematics , largely under the influence of Georg Kreisel . He started teaching philosophy, first part-time at Columbia University , then full-time at Brandeis University from 1965 to 1977. [ 1 ] He spent much of his last decade at Stanford University , writing and editing eight books, including parts of the Collected Works of Kurt Gödel .
From Frege to Gödel: A Source Book in Mathematical Logic (1967) [ 2 ] is an anthology of translations on the history of logic and the foundations of mathematics . It begins with the first complete translation of Frege 's 1879 Begriffsschrift , followed by 45 short pieces on mathematical logic and axiomatic set theory , originally published between 1889 and 1931. The anthology ends with Gödel 's landmark paper on the incompleteness of Peano arithmetic .
Nearly all the content of From Frege to Gödel: A Source Book in Mathematical Logic had only been available in a few North American university libraries (e.g., even the Library of Congress did not acquire a copy of the Begriffsschrift until 1964), and all but four pieces had to be translated from one of six continental European languages. When possible, the authors of the original texts reviewed the translations, and suggested corrections and amendments. Each piece was supplied with editorial footnotes and an introduction (mostly by Van Heijenoort but some by Willard Quine and Burton Dreben ); its references were combined into a comprehensive bibliography, and misprints, inconsistencies, and errors were corrected.
From Frege to Gödel: A Source Book in Mathematical Logic contributed to advancing the view that modern logic begins with, and builds on, the Begriffsschrift . Grattan-Guinness (2000) argues that this perspective on the history of logic is mistaken, because Frege employed an idiosyncratic notation and was significantly less read than Peano . Ironically, van Heijenoort (1967) is often cited by those who prefer the alternative model theoretic stance on logic and mathematics. Much of the history of that stance, whose leading lights include George Boole , Charles Sanders Peirce , Ernst Schröder , Leopold Löwenheim , Thoralf Skolem , Alfred Tarski , and Jaakko Hintikka , is covered in Brady (2000). From Frege to Gödel: A Source Book in Mathematical Logic underrated the algebraic logic of De Morgan , Boole, Peirce, and Schröder, but devoted more pages to Skolem than to anyone other than Frege, and included Löwenheim (1915), the founding paper on model theory.
Van Heijenoort had children with two of his four wives. While living with Trotsky in Coyoacán , van Heijenoort's first wife left him after an argument with Trotsky's spouse. In 1986, he visited his estranged fourth wife, Anne-Marie Zamora, in Mexico City where she murdered him [ 3 ] before taking her own life.
Van Heijenoort was also one of Frida Kahlo 's lovers; in the film Frida , he is played by Felipe Fulop.
Books which Van Heijenoort edited alone or with others: | https://en.wikipedia.org/wiki/Jean_van_Heijenoort |
Jeanette Grasselli Brown (born Jeanette Gecsy; August 4, 1928) is an American analytical chemist and spectroscopist who is known for her work with Standard Oil of Ohio (now BP America ) as an industrial researcher in the field of spectroscopy .
Spectroscopy is a technique used to measure the interaction of electromagnetic radiation with matter. [ 1 ] [ 2 ] Her areas of expertise encompass fields such as vibrational spectroscopy, combined instrumental techniques, computerized spectroscopy, and environmental spectroscopy. [ 3 ] She developed new techniques to solve problems like identifying contaminants in gasoline, analyzing the makeup of new plastics, and analyzing environmental problems such as pollution . [ 1 ]
During her career, Grasselli Brown has striven to bridge the gap between research and practical applications between industry and academia. She is considered one of the foremost contributors to infrared and Raman spectrometry of the 20th century. [ 2 ]
Grasselli Brown was born in 1928 to Hungarian immigrant parents Nicholas and Vera Gecsy. She grew up in a Hungarian neighborhood in the Buckeye Road area in Cleveland , Ohio during the Great Depression . [ 4 ] Her parents valued education and encouraged her to receive a college education in spite of economic and family difficulties. [ 5 ] Around 1946, her father opened a business in Elyria, Ohio , making sand cast aluminum parts. The foundry eventually failed and the family went bankrupt. Her brother Robert died from Hodgkin's lymphoma . While she was in college, her parents divorced. [ 4 ]
Grasselli Brown attended Harvey Rice Elementary School, Alexander Hamilton Junior High and John Adams High School in Cleveland, Ohio. At John Adams, she was in a college track program and planned to major in English in college. However, when she took her first chemistry class, she fell in love with the subject. [ 2 ] Her high school chemistry teacher told her if she majored in chemistry, he would be able to get her a scholarship to his alma mater, Ohio University , which he did. [ 6 ]
Grasselli Brown graduated from John Adams High School in 1946, [ 4 ] and attended Ohio University from 1946 to 1950. [ 2 ] She worked in the chemistry department as an assistant and in the library. She was a member of Phi Beta Kappa . [ 7 ] She was the only female chemist in her class and received her Bachelor of Science summa cum laude in 1950. [ 8 ] [ 9 ] In 1958, she received her Master of Science in chemistry from Case Western Reserve University . [ 3 ]
Grasselli Brown has received thirteen honorary degrees from various institutions including Ohio University (1978), Clarkson University (1986), Michigan Technology University (1989), Wilson College (1994), Case Western Reserve University (1995), Notre Dame College (1995), Kenyon College (1995), Mount Union College (1996), Cleveland State University (2000), Kent State University (2000), Ursuline College (2001), Youngstown State University (2003), and University Pecs , Hungary (2002). [ citation needed ]
After graduating from Ohio University in 1950, Grasselli Brown was offered a job position at Standard Oil (now BP America ) in Cleveland as a project leader. From 1950 to 1978, she worked closely with an instrument called an infrared spectrometer . This device is used to measure the absorbance, emission, and reflection of infrared light interacting with a molecule and also measures the vibrations of atoms to identify functional groups. [ 10 ]
During her time at Standard Oil, Grasselli Brown used the infrared spectrometer to examine the concentration of materials, and sought to find industrial applications for it. [ 8 ] [ 4 ] As a project leader, she analyzed the formulations of World War II German airplane fuels to understand how the German planes were able to extend their flight ranges. [ 1 ] She also consulted with the coroner's office in Cleveland to analyze unknown samples at crime scenes. [ 2 ]
In 1978, she became the manager of the analytical science laboratory, working there until 1983. In 1983, she became the director of the technological support department, working there until 1985, when she became the first female director of corporate research from 1985 to 1988. [ 2 ] Grasselli Brown retired in January 1989 as the company's highest ranking female employee. [ 11 ] [ 4 ]
From 1989 to 1995, Grasselli Brown worked as a distinguished visiting professor and director of research enhancement at her alma mater, Ohio University. She has also served as a chair of the board of trustees, chair of the Ohio Board of Regents , a Foundation Board trustee for nine years, and a member of the Cutler Scholars Board of governors. [ 12 ]
She has served on numerous committees and boards such as the National Science Foundation Advisory Committee for Analytic Chemistry (1982–1984), the Energy Research Advisory Board of the U.S. Department of Energy (1987–1989), the visiting committee of the National Institute of Standards and Technology (1988–1991), and the Smithsonian Institution's exhibition advisory board (1990–1994). She chaired the U.S. National Committee of the International Union of Pure and Applied Chemistry from 1992 to 1995. [ 1 ]
Grasselli Brown edited the international journal, Vibrational Spectroscopy . [ 3 ] She is a member of the American Chemical Society , Coblentz Society , Federation of Analytical Chemistry and Spectroscopy Societies , and the American Association for the Advancement of Science . She was the president of the Society for Applied Spectroscopy in 1970. She is active in promoting women's careers as a member of the International Women's Forum and National Research Council's Committee on Women in Science and Engineering. [ 1 ] She is an avid supporter of women in the workplace and defends part-time work for women, equal salaries, and corporate child-care facilities. [ 2 ]
Grasselli Brown has given over a hundred talks at scientific conferences, one hundred seminars for graduate students, and over five hundred lectures to the general public. [ 2 ] She continues to be widely requested as a speaker and consultant on industrial and environmental problems. She travels to Eastern Europe to teach the use of spectroscopy for soil, air, and water pollution issues. [ 2 ]
Grasselli Brown serves on the boards of numerous non-profit organizations such as the Cleveland Hungarian Development Panel, the Cleveland Orchestra , the Great Lakes Science Center , the Cleveland Clinic Foundation , Breakthru, the Holden Arboretum , Martha Holden Jennings Foundation, Musical Arts Association of the Cleveland Orchestra, One Community, IdeaStream , the Cleveland Scholarship Programs, Inc., and the Northeastern Ohio Science and Engineering Fair. [ 7 ]
Grasselli Brown has been married twice, to coworker Robert Grasselli (1957–1985) and to coworker Glenn Brown (1987–). Brown had two children from his previous marriage, Robyn and Eric; they now have three grandchildren. [ 4 ] Jeanette continues to use the name Grasselli since it is the name she is known by professionally. [ 2 ]
Grasselli Brown has over ninety publications, nine books, and a patent in the field of infrared and Raman spectroscopy . [ 13 ]
In 1985, she was selected as one of the Foremost Women of the 20th Century. [ 3 ] She is the first woman to be inducted into the Hungarian and Austrian Chemical Societies. [ 8 ] In 2002, Grasselli Brown received the National Ellis Medal of Honor and was selected as an International Scientist of the Year. [ 4 ] [ 3 ]
In 1991, Grasselli Brown was the first woman to be inducted into the Ohio Science and Technology Hall of Fame. [ 1 ] She was inducted into the Ohio Women's Hall of Fame in 1989 and is also a member of the Cleveland International Hall of Fame. [ 1 ] [ 4 ] In 2004, Grasselli Brown was chosen to be a part of the book "Ohio 200 years, 200 Women: Ohio's First and Finest." [ 4 ]
As of 2013, Jeanette Grasselli Brown donated her papers to the Mahn Center for Archives and Special Collections at her alma mater, Ohio University. [ 14 ]
In 2022, a permanent exhibit at the Great Lakes Science Center, entitled "Interactive Periodic Table of Element", was created through a donation by the Northeastern Ohio Science & Engineering Fair, in honor of Dr. Jeanette Grasselli Brown and her husband Dr. Glenn Brown. | https://en.wikipedia.org/wiki/Jeanette_Grasselli_Brown |
Jeannette Elizabeth Brown (born May 13, 1934 [ 1 ] ) is a retired American organic medicinal chemist, historian, and author.
Brown was born in 1934 in The Bronx, New York . According to Brown, when she was young, she contracted tuberculosis, and was treated by Arthur Logan. Logan was a young African-American in his intern year of residency, and lived in Brown's building. Brown's later inspiration to study science came from asking Logan how one could become a doctor. He replied, "Oh, you study science". [ 2 ] Brown excelled in particular in chemistry, scoring 98 out of 100 on the New York State Regents chemistry exam. [ 2 ] She attended New Dorp High School on Staten Island , and graduated in 1952. [ 2 ] [ 3 ] Brown earned her bachelor's degree in chemistry at Hunter College in 1956, one of two African Americans in the inaugural class of Hunter's chemistry program. [ 4 ] In 1958, she became the first African American woman to achieve a master's degree from the University of Minnesota in organic chemistry. [ 5 ] Her master's thesis was entitled "Study of Dye and Ylide Formation in Salts of 9-(P-dimethylaminophenyl) Fluorene."
After receiving her master's degree, Brown began work as a research chemist at CIBA Pharmaceutical Company , where she was involved in research programs for drug development targeting tuberculosis and coccidiosis . She moved to Merck in 1969, where she co-authored 15 publications, obtained one patent and contributed to five others. Brown's work focused on synthesizing novel medicinal compounds. She worked to develop the compound cilastatin sodium. Cilastatin is an inhibitor of renal dehydropeptidase. Since the antibiotic, imipenem, is one such antibiotic that is hydrolyzed by dehydropeptidase, cilastatin is used in combination with imipenem to prevent its metabolism. [ 6 ] This combination creates the antibiotic Primaxin (imipenem/cilastatin) , which is used to treat severe internal infections, as well as diseases caused by flesh-eating bacteria and some types of pneumonia .
In order to succeed in industry, she believed that one needed to be an effective communicator, be able to work on a team, and have a strong scientific education in an ever-changing field.
Brown spent 36 years in research before she switched over to education. From 1993 to 2002 she was a visiting professor at the New Jersey Institute of Technology , [ 3 ] [ 4 ] where she also helped recruit black students to enter STEM fields and worked on science education issues in the state. It was here that she also tutored middle school and high school chemistry teachers. She won a grant from the Camille and Henry Dreyfus Foundation , which she put towards tutoring chemistry teachers. Brown has also devoted significant professional effort to diversity and outreach projects; she served on the National Science Foundation Committee on Equal Opportunities for Women Minorities and Persons with Disabilities and was the historian of the American Chemical Society 's Women Chemist Committee. [ 4 ] To this day, Brown continues to mentor both middle and high school students through the Freddie and Ada Brown Award. She founded this award in 2010 in honor of her parents.
As a historian of science, Brown contributed seven biographical profiles of African American chemists to the African American National Biography Project , which included the first African American women to get their Ph.Ds in chemistry and chemical engineering. [ 3 ] She is the author of the 2011 book African American Women Chemists , which profiles early African American women in chemistry. [ 7 ] Her second book, African American Women Chemists in the Modern Era , focuses on contemporary women who have benefited from the Civil Rights Act and are now working as chemists or chemical engineers.
In an interview with the University of Minnesota, Brown advises young women entering the scientific fields to plow ahead despite the inevitable slights that will come their way. “You just got to keep going,” she said. “You can't stop. If you stop, you're not going to get what you want.” [ 8 ]
“Go straight for a Ph.D. Do not stop at a master's degree,” she said. “If you're a Ph.D., then you're the boss.” [ 8 ]
"I think working hard and learning new things keeps you young." [ 2 ] | https://en.wikipedia.org/wiki/Jeannette_Brown |
In astrophysics and statistical mechanics , Jeans's theorem , named after James Jeans , states that any steady-state solution of the collisionless Boltzmann equation depends on the phase space coordinates only through integrals of motion in the given potential, and conversely any function of the integrals is a steady-state solution.
Jeans's theorem is most often discussed in the context of potentials characterized by three, global integrals. In such potentials, all of the orbits are regular, i.e. non- chaotic ; the Kepler potential is one example. In generic potentials, some orbits respect only one or two integrals and the corresponding motion is chaotic. Jeans's theorem can be generalized to such potentials as follows: [ 1 ]
The phase-space density of a stationary stellar system is constant within every well-connected region.
A well-connected region is one that cannot be decomposed into two finite regions such that all trajectories lie, for all time, in either one or the other. Invariant tori of regular orbits are such regions, but so are the more complex parts of phase space associated with chaotic trajectories. Integrability of the motion is therefore not required for a steady state.
Consider the collisionless Boltzmann equation for the distribution function f ( x , v , t ) {\displaystyle f(\mathbf {x} ,\mathbf {v} ,t)}
Consider the Lagrangian approach to the particle's motion in which case, the required equations are
Let the solutions of these equations be
where α i {\displaystyle \alpha _{i}} s are the integration constants. Let us assume that from the above set, we are able to solve α i {\displaystyle \alpha _{i}} , that is to say, we are able to find
Now consider an arbitrary function of α i {\displaystyle \alpha _{i}} 's,
Then this function is the solution of the collisionless Boltzmann equation, as can be verified by substituting this function into the collisionless Boltzmann equation to find [ 2 ] [ 3 ]
This proves the theorem.
A trivial set of integration constants are the initial location x 0 {\displaystyle \mathbf {x} _{0}} and the initial velocities v 0 {\displaystyle \mathbf {v} _{0}} of the particle. In this case, any function
is a solution of the collisionless Boltzmann equation.
This astrophysics -related article is a stub . You can help Wikipedia by expanding it .
This statistics -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Jeans's_theorem |
The Jeans instability is a concept in astrophysics that describes an instability that leads to the gravitational collapse of a cloud of gas or dust. [ 1 ] It causes the collapse of interstellar gas clouds and subsequent star formation. It occurs when the internal gas pressure is not strong enough to prevent the gravitational collapse of a region filled with matter. [ 2 ] It is named after James Jeans .
For stability, the cloud must be in hydrostatic equilibrium , which in case of a spherical cloud translates to
d p d r = − G ρ ( r ) M enc ( r ) r 2 {\textstyle {\frac {dp}{dr}}=-{\frac {G\rho (r)M_{\text{enc}}(r)}{r^{2}}}} ,
where M enc ( r ) {\textstyle M_{\text{enc}}(r)} is the enclosed mass, p is the pressure, ρ ( r ) {\textstyle \rho (r)} is the density of the gas (at radius r ), G is the gravitational constant , and r is the radius. The equilibrium is stable if small perturbations are damped and unstable if they are amplified. In general, the cloud is unstable if it is either very massive at a given temperature or very cool at a given mass; under these circumstances, the gas pressure gradient cannot overcome gravitational force, and the cloud will collapse. [ 3 ] This is called the "Jeans Collapse Criterion".
The Jeans instability likely determines when star formation occurs in molecular clouds .
In 1720, Edmund Halley considered a universe without edges and pondered what would happen if the "system of the world", which exists within the universe, were finite or infinite. In the finite case, stars would gravitate towards the center, and if infinite, all the stars would be nearly in equilibrium and the stars would eventually reach a resting place. [ 4 ] Contrary to the writing of Halley, Isaac Newton , in a 1692/3 letter to Richard Bentley , wrote that it's hard to imagine that particles in an infinite space should be able to stand in such a configuration to result in a perfect equilibrium. [ 5 ] [ 6 ]
James Jeans extended the issue of gravitational stability to include pressure. In 1902, Jeans wrote, similarly to Halley, that a finite distribution of matter, assuming pressure does not prevent it, will collapse gravitationally towards its center. For an infinite distribution of matter, there are two possible scenarios. An exactly homogeneous distribution has no clear center of mass and no clear way to define a gravitational acceleration direction. For the other case, Jeans extends what Newton wrote about: Jeans demonstrated that small deviations from exact homogeneity lead to instabilities. [ 7 ]
The Jeans mass is named after the British physicist Sir James Jeans , who considered the process of gravitational collapse within a gaseous cloud. He was able to show that, under appropriate conditions, a cloud, or part of one, would become unstable and begin to collapse when it lacked sufficient gaseous pressure support to balance the force of gravity . The cloud is stable for sufficiently small mass (at a given temperature and radius), but once this critical mass is exceeded, it will begin a process of runaway contraction until some other force can impede the collapse. He derived a formula for calculating this critical mass as a function of its density and temperature . The greater the mass of the cloud, the bigger its size, and the colder its temperature, the less stable it will be against gravitational collapse.
The approximate value of the Jeans mass may be derived through a simple physical argument. One begins with a spherical gaseous region of radius R , mass M , and with a gaseous sound speed c S . The gas is compressed slightly and it takes a time
t sound = R c s ≈ 0.5 Myr ⋅ R 0.1 pc ⋅ ( c s 0.2 km/s ) − 1 {\textstyle t_{\text{sound}}={\frac {R}{c_{\text{s}}}}\approx 0.5{\text{ Myr}}\cdot {\frac {R}{0.1{\text{ pc}}}}\cdot \left({\frac {c_{\text{s}}}{0.2{\text{ km/s}}}}\right)^{-1}}
for sound waves to cross the region and attempt to push back and re-establish the system in pressure balance. At the same time, gravity will attempt to contract the system even further, and will do so on a free-fall time
t ff = 1 ( G ρ ) 1 / 2 ≈ 2 Myr ⋅ ( n 10 3 cm − 3 ) − 1 / 2 {\textstyle t_{\text{ff}}={\frac {1}{(G\rho )^{1/2}}}\approx 2{\text{ Myr}}\cdot \left({\frac {n}{10^{3}{\text{ cm}}^{-3}}}\right)^{-1/2}} ,
where G is the universal gravitational constant, ρ {\textstyle \rho } is the gas density within the region, and n = ρ / μ {\textstyle n=\rho /\mu } is the gas number density for mean mass per particle ( μ = 3.9 × 10^ −24 g is appropriate for molecular hydrogen with 20% helium by number). When the sound-crossing time is less than the free-fall time, pressure forces temporarily overcome gravity, and the system returns to a stable equilibrium. However, when the free-fall time is less than the sound-crossing time, gravity overcomes pressure forces, and the region undergoes gravitational collapse . The condition for gravitational collapse is therefore t ff < t sound {\displaystyle t_{\text{ff}}<t_{\text{sound}}} .
The resultant Jeans length λ J is approximately λ J = c s ( G ρ ) 1 / 2 ≈ 0.4 pc ⋅ c s 0.2 km/s ⋅ ( n 10 3 cm − 3 ) − 1 / 2 {\textstyle \lambda _{\text{J}}={\frac {c_{\text{s}}}{(G\rho )^{1/2}}}\approx 0.4{\text{ pc}}\cdot {\frac {c_{\text{s}}}{0.2{\text{ km/s}}}}\cdot \left({\frac {n}{10^{3}{\text{ cm}}^{-3}}}\right)^{-1/2}} .
This length scale is known as the Jeans length. All scales larger than the Jeans length are unstable to gravitational collapse, whereas smaller scales are stable. The Jeans mass M J is just the mass contained in a sphere of radius R J ( R J = 1 2 λ J {\textstyle R_{\text{J}}={\frac {1}{2}}\lambda _{\text{J}}} is half the Jeans length):
M J = 4 π 3 ρ R J 3 = π 6 ⋅ c s 3 G 3 / 2 ρ 1 / 2 ≈ 2 M ⊙ ⋅ ( c s 0.2 km/s ) 3 ( n 10 3 cm − 3 ) − 1 / 2 {\textstyle M_{\text{J}}={\frac {4\pi }{3}}\rho R_{\text{J}}^{3}={\frac {\pi }{6}}\cdot {\frac {c_{\text{s}}^{3}}{G^{3/2}\rho ^{1/2}}}\approx 2{\text{ M}}_{\odot }\cdot \left({\frac {c_{\text{s}}}{0.2{\text{ km/s}}}}\right)^{3}\left({\frac {n}{10^{3}{\text{ cm}}^{-3}}}\right)^{-1/2}} .
It was later pointed out by other astrophysicists, including Binney and Tremaine, [ 8 ] that the original analysis used by Jeans was flawed: in his formal analysis, although Jeans assumed that the collapsing region of the cloud was surrounded by an infinite, static medium, the surrounding medium should in reality also be collapsing, since all larger scales are also gravitationally unstable by the same analysis. The influence of this medium was completely ignored in Jeans' analysis. This flaw has come to be known as the " Jeans' swindle ".
When using a more careful analysis taking into account other factors such as the expansion of the Universe fortuitously cancel out the apparent error in Jeans' analysis, and Jeans' equation is correct, even if its derivation might have been dubious. [ 9 ]
An alternative, arguably even simpler, derivation can be found using energy considerations. In the interstellar cloud, two opposing forces are at work. The gas pressure, caused by the thermal movement of the atoms or molecules comprising the cloud, tries to make the cloud expand, whereas gravitation tries to make the cloud collapse. The Jeans mass is the critical mass where both forces are in equilibrium with each other. In the following derivation numerical constants (such as π) and constants of nature (such as the gravitational constant ) will be ignored. They will be reintroduced in the result.
Consider a homogeneous spherical gas cloud with radius R . In order to compress this sphere to a radius R − d R {\textstyle R-dR} , work must be done against the gas pressure. During the compression, gravitational energy is released. When this energy equals the amount of work to be done on the gas, the critical mass is attained. Let M be the mass of the cloud, T the (absolute) temperature, n the particle density, and p the gas pressure. The work to be done equals pdV . Using the ideal gas law, according to which p = n T {\textstyle p=nT} , one arrives at the following expression for the work:
d W = n T R 2 d R {\textstyle dW=nTR^{2}\,dR} .
The gravitational potential energy of a sphere with mass M and radius R is, apart from constants, given by the following expression:
U = M 2 R {\textstyle U={\frac {M^{2}}{R}}} .
The amount of energy released when the sphere contracts from radius R to radius R − d R {\textstyle R-dR} is obtained by differentiation this expression to R , so
d U = M 2 R 2 d R {\textstyle dU={\frac {M^{2}}{R^{2}}}\,dR} .
The critical mass is attained as soon as the released gravitational energy is equal to the work done on the gas:
M 2 R 2 = n T R 2 {\textstyle {\frac {M^{2}}{R^{2}}}=nTR^{2}} .
Next, the radius R must be expressed in terms of the particle density n and the mass M . This can be done using the relation
M = n R 3 {\textstyle M=nR^{3}} .
A little algebra leads to the following expression for the critical mass:
M J = ( T 3 n ) 1 / 2 {\textstyle M_{\text{J}}=\left({\frac {T^{3}}{n}}\right)^{1/2}} .
If during the derivation all constants are taken along, the resulting expression is
M J = ( 375 k B 3 4 π m 4 G 3 ) 1 / 2 ( T 3 n ) 1 / 2 {\textstyle M_{\text{J}}=\left({\frac {375k_{\text{B}}^{3}}{4\pi m^{4}G^{3}}}\right)^{1/2}\left({\frac {T^{3}}{n}}\right)^{1/2}} ,
where k B is the Boltzmann constant , G the gravitational constant , and m the mass of a particle comprising the gas. Assuming the cloud to consist of atomic hydrogen, the prefactor can be calculated. If we take the solar mass as the unit of mass, and use units of m −3 for the particle density, the result is
M J = 3 × 10 4 ( T 3 n ) 1 / 2 {\textstyle M_{\text{J}}=3\times 10^{4}\left({\frac {T^{3}}{n}}\right)^{1/2}} .
Jeans' length is the critical radius of a cloud (typically a cloud of interstellar molecular gas and dust) where thermal energy, which causes the cloud to expand, is counteracted by gravity, which causes the cloud to collapse. It is named after the British astronomer Sir James Jeans , who concerned himself with the stability of spherical nebulae in the early 1900s. [ 7 ]
The formula for Jeans' length is:
λ J = ( 15 k B T 4 π G μ ρ ) 1 / 2 {\textstyle \lambda _{\text{J}}=\left({\frac {15k_{\text{B}}T}{4\pi G\mu \rho }}\right)^{1/2}}
where k B is the Boltzmann constant , T is the temperature of the cloud, μ is the mean molecular weight of the particles, G is the gravitational constant , and ρ is the cloud's mass density (i.e. the cloud's mass divided by the cloud's volume). [ 10 ] [ 11 ]
A way to conceptualize Jeans' length is in terms of a close approximation, in which the factors 15 and 4π are discarded and in which ρ is rephrased as M / r 3 {\textstyle M/r^{3}} . The formula for Jeans' length then becomes
λ J ≈ ( k B T r 3 G M μ ) 1 / 2 {\textstyle \lambda _{\text{J}}\approx \left({\frac {k_{\text{B}}Tr^{3}}{GM\mu }}\right)^{1/2}} ,
where r is the radius of the cloud.
It follows immediately that λ J = r {\textstyle \lambda _{\text{J}}=r} when k B T = G M μ / r {\textstyle k_{\text{B}}T=GM\mu /r} ; i.e., the cloud's radius is the Jeans' length when thermal energy per particle equals gravitational work per particle. At this critical length, the cloud neither expands nor contracts. It is only when thermal energy is not equal to gravitational work that the cloud either expands and cools or contracts and warms, a process that continues until equilibrium is reached.
The Jeans' length is the oscillation wavelength (respectively, Jeans' wavenumber , k J ) below which stable oscillations rather than gravitational collapse will occur.
λ J = 2 π k J = c s ( π G ρ ) 1 / 2 {\textstyle \lambda _{\text{J}}={\frac {2\pi }{k_{\text{J}}}}=c_{\text{s}}\left({\frac {\pi }{G\rho }}\right)^{1/2}} ,
where G is the gravitational constant , c S is the sound speed , and ρ is the enclosed mass density.
It is also the distance a sound wave would travel in the collapse time.
Jeans instability can also give rise to fragmentation in certain conditions. To derive the condition for fragmentation an adiabatic process is assumed in an ideal gas and also a polytropic equation of state is taken. The derivation is shown below through a dimensional analysis:
For an ideal gas , P V = n R T ⇒ P ⋅ P − 1 / γ = P ( γ − 1 ) / γ ∝ T ⇒ P ∝ T γ / ( γ − 1 ) {\displaystyle PV=nRT\Rightarrow P\cdot P^{-1/\gamma }=P^{(\gamma -1)/\gamma }\propto T\Rightarrow P\propto T^{\gamma /(\gamma -1)}} .
Polytropic equation of state , P = K ρ γ → T ∝ ρ γ − 1 {\displaystyle P=K\rho ^{\gamma }\rightarrow T\propto \rho ^{\gamma -1}} .
Jeans mass, M J ∝ T 3 / 2 ρ − 1 / 2 ∝ ρ ( 3 / 2 ) ( γ − 1 ) ρ − 1 / 2 {\displaystyle M_{\text{J}}\propto T^{3/2}\rho ^{-1/2}\propto \rho ^{(3/2)(\gamma -1)}\rho ^{-1/2}} .
If the adiabatic index γ > 4 3 {\textstyle \gamma >{\frac {4}{3}}} , the Jeans mass increases with increasing density, while if γ < 4 3 {\textstyle \gamma <{\frac {4}{3}}} the Jeans mass decreases with increasing density. During gravitational collapse density always increases, [ 12 ] thus in the second case the Jeans mass will decrease during collapse, allowing smaller overdense regions to collapse, leading to fragmentation of the giant molecular cloud. For an ideal monatomic gas, the adiabatic index is 5/3. However, in astrophysical objects this value is usually close to 1 (for example, in partially ionized gas at temperatures low compared to the ionization energy). [ 13 ] More generally, the process is not really adiabatic but involves cooling by radiation that is much faster than the contraction, so that the process can be modeled by an adiabatic index as low as 1 (which corresponds to the polytropic index of an isothermal gas). [ citation needed ] So the second case is the rule rather than an exception in stars. This is the reason why stars usually form in clusters. | https://en.wikipedia.org/wiki/Jeans_instability |
A Jecklin disk is a sound-absorbing disk placed between two microphones to create an acoustic "shadow" from one microphone to the other. The resulting two signals can produce a pleasing stereo effect on headphones and loudspeakers but are sometimes not fully mono-compatible. A matching pair of small-diaphragm omnidirectional microphones is generally used for this technique, although it is possible to use other kinds of microphones resulting in more subtle effects.
This technique was invented by Jürg Jecklin , the former chief sound engineer of Swiss Radio and teacher at the University for Music and Performing Arts in Vienna. He referred to the technique as an "Optimal Stereo Signal" (OSS).
It is a refinement of the baffled microphone technique for stereo initially described by Alan Blumlein in his 1931 patent on binaural sound.
In the beginning Jecklin used omnidirectional microphones on either side of a 30 cm (0.98 ft) disk about 2 cm ( 3 ⁄ 4 in) thick, which had a muffling layer of soft plastic foam or wool fleece on each side. The capsules of the microphones were above the surface of the disc, just in the center, 16.5 cm ( 6 + 1 ⁄ 2 in) apart from each other and each pointing 20 degrees outside. Jecklin later found the 16.5 cm ( 6 + 1 ⁄ 2 in) ear spacing between the microphones too narrow. In his own paper, he notes that the disk has to be 35 cm ( 13 + 3 ⁄ 4 in) in diameter and the distance between the microphones should be 36 cm ( 14 + 3 ⁄ 16 in).
Jecklin's German from his script: "Zwei Kugelmikrofone sind mit einem gegenseitigen Abstand von 36 cm angeordnet und durch eine mit Schaumstoff belegte Scheibe von 35 cm Durchmesser akustisch getrennt." [ 1 ]
The effect of the baffle is to introduce some of the frequency-response, time and amplitude variations human listeners experience as positioning cues, but in such a way that the recording also produces a useful stereo image through loudspeakers. This is sometimes known as "the Jecklin effect". There is currently no known software that can emulate this effect convincingly.
There are multiple variations of this technique, with "discs" of varying sizes and shapes, all of which work to some degree in helping to create a recording with a more believable stereo "image" than a spaced pair of microphones, but the size of the barrier is critically related to the lowest frequency at which it operates. A barrier which is too small will start operating at frequencies which are above the region of the spectrum where human hearing is most sensitive.
In contrast, traditional binaural recordings made using a mannequin head or on-ear microphones work very well when played back over headphones, especially when combined with HRTF correction, but are not as convincing and can actually sound quite unpleasant when played back through speakers. | https://en.wikipedia.org/wiki/Jecklin_disk |
Jeehiun Katherine Lee is an organic chemist and a professor in the department of chemistry at Rutgers University . She currently runs a research lab on the New Brunswick campus. [ 1 ]
Although she is an organic chemist by training, she has expanded her research field to biological chemistry, using mass spectrometry , computer modeling and other methods to characterize reactivity and catalysis. [ 2 ]
Lee's group combines experimental and computational methods to understand mechanisms of reactions important for chemistry and biology. Specifically, Lee has pioneered the use of traditionally physical methods, primarily mass spectrometry and computational chemistry , to tackle problems at the chemistry/biology interface, focusing on catalysis. [ citation needed ]
Lee received her BA summa cum laude in Chemistry at Cornell University in 1990. She obtained her PhD in organic chemistry at Harvard University in 1994.
From 1995 to 1997, Lee was a NIH Postdoctoral Research Fellow at UCLA in the lab of Kendall N. Houk . [ 3 ]
Lee also teaches classes in organic chemistry for undergraduate students and advanced organic chemistry for graduate students. | https://en.wikipedia.org/wiki/Jeehiun_Lee |
The jeep problem , [ 1 ] desert crossing problem [ 2 ] or exploration problem [ 3 ] is a mathematics problem in which a jeep must maximize the distance it can travel into a desert with a given quantity of fuel. The jeep can only carry a fixed and limited amount of fuel, but it can leave fuel and collect fuel at fuel dumps anywhere in the desert.
The problem first appeared in the 9th-century collection Propositiones ad Acuendos Juvenes ( Problems to Sharpen the Young ), attributed to Alcuin , with the puzzle being about a travelling camel eating grain. [ 4 ] The De viribus quantitatis (c. 1500) of Luca Pacioli also discusses the problem. A modern treatment was given by N. J. Fine in 1947. [ 1 ]
There are n units of fuel stored at a fixed base. The jeep can carry at most 1 unit of fuel at any time, and can travel 1 unit of distance on 1 unit of fuel (the jeep's fuel consumption is assumed to be constant). At any point in a trip the jeep may leave any amount of fuel that it is carrying at a fuel dump, or may collect any amount of fuel that was left at a fuel dump on a previous trip, as long as its fuel load never exceeds 1 unit. There are two variants of the problem:
In either case the objective is to maximize the distance traveled by the jeep on its final trip. Alternatively, the objective may be to find the least amount of fuel required to produce a final trip of a given distance.
In the classic problem the fuel in the jeep and at fuel dumps is treated as a continuous quantity. More complex variations on the problem have been proposed in which the fuel can only be left or collected in discrete amounts. [ 5 ]
A strategy that maximizes the distance traveled on the final trip for the "exploring the desert" variant is as follows:
When the jeep starts its final trip, there are n − 1 fuel dumps. The farthest contains 1/2 of a unit of fuel, the next farthest contain 1/3 of a unit of fuel, and so on, and the nearest fuel dump has just 1/ n units of fuel left. Together with 1 unit of fuel with which it starts from base, this means that the jeep can travel a total round trip distance of
units on its final trip (the maximum distance traveled into the desert is half of this). [ 3 ] It collects half of the remaining fuel at each dump on the way out, which fills its tank. After leaving the farthest fuel dump it travels 1/2 a unit further into the desert and then returns to the farthest fuel dump. It collects the remaining fuel from each fuel dump on the way back, which is just enough to reach the next fuel dump or, in the final step, to return to base.
The distance travelled on the last trip is the n th harmonic number , H n . As the harmonic numbers are unbounded, it is possible to exceed any given distance on the final trip, as along as sufficient fuel is available at the base. However, the amount of fuel required and the number of fuel dumps both increase exponentially with the distance to be traveled.
The "crossing the desert" variant can be solved with a similar strategy, except that there is now no requirement to collect fuel on the way back on the final trip. So on trip k the jeep establishes a new k th fuel dump at a distance of 1/(2 n − 2 k + 1) units from the previous fuel dump and leaves (2 n − 2 k − 1)/(2 n − 2 k + 1) units of fuel there. On each of the next n − k − 1 trips it collects 1/(2 n − 2 k + 1) units of fuel from the k th dump on its way out and another 1/(2 n − 2 k + 1) units of fuel on its way back.
Now when the jeep starts its final trip, there are n − 1 fuel dumps. The farthest contains 1/3 of a unit of fuel, the next farthest contain 1/5 of a unit of fuel, and so on, and the nearest fuel dump has just 1/(2 n − 1) units of fuel left. Together with 1 unit of fuel with which it starts from base, this means that the jeep can travel a total distance of
units on its final trip. [ 1 ] [ 3 ] It collects all of the remaining fuel at each dump on the way out, which fills its tank. After leaving the farthest fuel dump it travels a further distance of 1 unit.
Since
it is possible in theory to cross a desert of any size given enough fuel at the base. As before, the amount of fuel required and the number of fuel dumps both increase exponentially with the distance to be traveled.
In summary, the maximum distance reachable by the jeep (with a fuel capacity for 1 unit of distance at any time) in n trips (with n-1 midway fuel dumps and consuming a total of n units of fuel) is
Here H n = 1 + 1 2 + 1 3 + ⋯ + 1 n {\displaystyle H_{n}=1+{\frac {1}{2}}+{\frac {1}{3}}+\cdots +{\frac {1}{n}}} is the nth harmonic number .
The number of fuel units available at the base need not be an integer. In the general case, the maximum distance achievable for the "explore the desert" problem with n units of fuel is
with the first fuel dump located at { n } / ( 2 ⌈ n ⌉ ) {\displaystyle \{n\}/(2\lceil n\rceil )} units of distance away from the starting base, the second one at 1 / ( 2 ⌈ n ⌉ − 2 ) {\displaystyle 1/(2\lceil n\rceil -2)} units of distance away from the first fuel dump, the third one at 1 / ( 2 ⌈ n ⌉ − 4 ) {\displaystyle 1/(2\lceil n\rceil -4)} units of distance away from the second fuel dump, and so on. Here { n } = n − ⌊ n ⌋ {\displaystyle \{n\}=n-\lfloor n\rfloor } is the fractional part of n .
The maximum distance achievable for the "cross the desert" problem with n units of fuel is
with the first fuel dump located at { n } / ( 2 ⌈ n ⌉ − 1 ) {\displaystyle \{n\}/(2\lceil n\rceil -1)} units of distance away from the starting base, the second one at 1 / ( 2 ⌈ n ⌉ − 3 ) {\displaystyle 1/(2\lceil n\rceil -3)} units of distance away from the first fuel dump, the third one at 1 / ( 2 ⌈ n ⌉ − 5 ) {\displaystyle 1/(2\lceil n\rceil -5)} units of distance away from the second fuel dump, and so on. Here { n } = n − ⌊ n ⌋ {\displaystyle \{n\}=n-\lfloor n\rfloor } is the fractional part of n .
The order of the jeep trips is not fixed. For example in the "exploring the desert" version of the problem, the jeep could make n − 1 round-trips between the base and the first fuel dump, leaving ( n − 1) / n units of fuel at the fuel dump each time and then make an n -th trip one-way to the first fuel dump, thus arriving there with a total of ( n − 1) + 1/(2 n ) units of fuel available. The 1/(2 n ) units are saved for the return trip to base at the very end and the other n − 1 units of fuel are used to move fuel between the first and second fuel dump, using n − 2 round-trips and then an ( n −1) -th trip one-way to the second fuel dump. And so on.
The problem can have a practical application in wartime situations, especially with respect to fuel efficiency . In the context of the bombing of Japan in World War II by B-29s , Robert McNamara says in the film The Fog of War that understanding the fuel efficiency issue caused by having to transport the fuel to forward bases was the main reason why the strategy of launching bombing raids from mainland China was abandoned in favor of the island hopping strategy:
"We had to fly those planes from the bases in Kansas to India. Then we had to fly fuel over the hump into China. [...] We were supposed to take these B-29s —there were no tanker aircraft there. We were to fill them with fuel, fly from India to Chengtu ; offload the fuel; fly back to India; make enough missions to build up fuel in Chengtu; fly to Yawata , Japan ; bomb the steel mills ; and go back to India.
We had so little training on this problem of maximizing [fuel] efficiency, we actually found to get some of the B-29s back instead of offloading fuel, they had to take it on. To make a long story short, it wasn't worth a damn. And it was LeMay who really came to that conclusion, and led the Chiefs to move the whole thing to the Marianas , which devastated Japan." [ 6 ]
(The atomic bombing missions at the end of World War II were flown using B-29 Superfortresses from the Pacific island of Tinian in the Northern Marianas Islands .) | https://en.wikipedia.org/wiki/Jeep_problem |
Jeevan Pramaan is an Indian Life Certificate program affiliated with Aadhaar for people with pensions. [ 1 ] It was started by Prime Minister Narendra Modi on 10 November 2014. [ 2 ] [ 3 ]
The certificate was made for people who receive pensions from central or state governments or other government organisations. [ 1 ]
Jeevan Pramaan was made by the Department of Electronics and IT, Government of India . [ 4 ] [ 5 ] [ 6 ] [ 7 ]
The Jeevan Pramaan software can be downloaded from https://jeevanpramaan.gov.in/ & from the Google Play Store for both PC and Android devices. This procedure can also be completed in one of the several Jeevan Pramaan Centres. A pension recipient can receive an electronic Jeevan Praaman certificate by using this software and a fingerprint or iris scan, as well as the Aadhaar platform for identification. The certificate can then be made available electronically to the Pension Disbursing Agency. [ 1 ]
This software article is a stub . You can help Wikipedia by expanding it .
This India -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Jeevan_Pramaan |
Jeewanu ( Sanskrit for "particles of life") are synthetic chemical particles that possess cell -like structure and seem to have some functional properties; that is, they are a model of primitive cells, or protocells . [ 1 ] [ 2 ] [ 3 ] It was first synthesised by Krishna Bahadur (20 January 1926 — 5 August 1994), an Indian chemist and his team in 1963. [ 4 ] [ 5 ] [ 6 ] Using photochemical reaction , they produced coacervates , microscopic cell-like spheres from a mixture of simple organic and inorganic compounds . Bahadur named these particles 'Jeewanu' because they exhibit some of the basic properties of a cell, such as the presence of semipermeable membrane , amino acids , phospholipids and carbohydrates . Further, like living cells, they had several catalytic activities. [ 1 ] Jeewanu are cited as models of protocells for the origin of life , [ 7 ] [ 8 ] and as artificial cells . [ 1 ]
Jeewanu is derived from Sanskrit जीव jīvá , meaning "life", and अणु aṇu , meaning "smallest particle", or the "indivisible". In contemporary Hindi , jeewanu also means unicellular organisms such as bacteria. Bahadur specifically used the term to represent the Indian philosophical tradition not only through the use of Sanskrit but also by inferring ideas on the origin of life from the Vedas . Bahadur, while employing the traditional Hindu philosophy, attempted to incorporate the advances in cell biology to the concept of abiogenesis . [ 1 ]
In 1954 [ 9 ] and 1958 Krishna Bahadur and co-workers published the successful synthesis of amino acids from a mixture of paraformaldehyde , colloidal molybdenum oxide or potassium nitrate and ferric chloride under sunlight. [ 10 ] It appears that this experimental approach was seminal for the assays to produce Jeewanu, which he first reported in 1963 in an obscure Indian journal, Vijnana Parishad Anusandhan Patrika . [ 4 ] His detailed syntheses were published in Germany in 1964 in a series of articles. [ 11 ]
Their initial experiment consisted of a sterilised apparatus in which inorganic nitrogenous compounds (such as ammonium phosphate and ammonium molybdate ) and organic compounds such as citric acid (C 6 H 8 O 7 ), paraformaldehyde (OH(CH 2 O) n H) and formaldehyde (CH 2 O) for carbon sources were mixed with minerals commonly found in living cells. [ 2 ] [ 12 ] Inorganic substances such as colloidal ferric chloride or molybdenum compounds supposedly acted as cofactors and catalysts. [ 1 ] [ 10 ] [ 13 ]
When the apparatus was exposed to sunlight for several days and constantly shaken, microscopic spherical particles were formed. The interesting features of these particles were that they were enclosed in a semipermeable membrane, like the typical cell membrane . Like living cells, they were reported to contain amino acids, phospholipid membrane and carbohydrates . [ 2 ] [ 14 ] [ 15 ] In addition, they were claimed to have reproductive capability by budding , much like unicellular organisms , but did not grow on any bacterial culture medium. [ 2 ] Bahadur reported that the Jeewanu exhibited various catalytic properties and produced their own peptides by metabolic reactions. [ 2 ] Bahadur's later work on the Jeewanu also detected the presence of amino acids in peptide form and sugars in the form of ribose , deoxyribose , fructose and glucose , as well as nucleic acid bases ( DNA and RNA building blocks) including adenine , guanine , cytosine , thymine and uracil . [ 2 ] [ 16 ] [ 17 ] Bahadur also reported having detected ATPase -like and peroxidase -like activity. Bahadur stated that by using molybdenum as a cofactor, the Jeewanu showed capability of reversible photochemical electron transfer , and released a gas mixture of oxygen and hydrogen at a 1:2 ratio. [ 2 ] [ 13 ]
Bahadur's publications were ambivalently received, and the overall attention of the scientific community seemed limited since Krishna Bahadur and his co-workers reported that the Jeewanus are alive (a striking statement), the team changed the protocols frequently and documented them somewhat idiosyncratically. [ 1 ] Bahadur defined "living units" as "[...] those which grow, multiply, and are metabolically active in a systematic, harmonious, and synchronized manner". [ 5 ] [ 11 ] Then, NASA's Exobiology Division tasked two biologists in 1967 to review and evaluate the literature so far published by Krishna Bahadur (not to replicate the experiments) on the synthesis and characteristics of the Jeewanu. [ 11 ] [ 18 ] The two NASA biologists did not debate whether these three criteria are an adequate definition of life , but whether the Jeewanu satisfy these criteria. [ 18 ] The NASA report concluded that "the evidence presented on these three points is on the whole unconvincing". The report also stated that the postulated existence of these living units has not been proved and "the nature and properties of the Jeewanu remains to be clarified." [ 18 ]
In the 1980s, the Hungarian chemist Tibor Gánti discussed the Jeewanu at length in his ' chemoton theory'—an abstract model of autocatalytic chemical reactions—published first in Hungarian and translated into English in 2003. [ 1 ] In the context of self-organizing structures, Gánti considered the Jeewanu a promising model system to understand the origin and fundamentals of life, and one that had never received due attention. [ 7 ] In 2011, a German scientist stated that the Jeewanu story pertains to concepts of life, its beginnings, as well as possible artificially created cells. [ 1 ]
Experimental duplication work published in 2013 by Gupta and Rai reported that their size varies from 0.5 μ to 3.5 μ in diameter, growth from within, metabolic activities, and "the presence of RNA-like material". [ 12 ] The authors stated that the RNA-like material detected in the Jeewanu protocells support the RNA world hypothesis . [ 12 ] [ 19 ] | https://en.wikipedia.org/wiki/Jeewanu |
In fluid dynamics Jeffery–Hamel flow is a flow created by a converging or diverging channel with a source or sink of fluid volume at the point of intersection of the two plane walls. It is named after George Barker Jeffery (1915) [ 1 ] and Georg Hamel (1917), [ 2 ] but it has subsequently been studied by many major scientists such as von Kármán and Levi-Civita , [ 3 ] Walter Tollmien , [ 4 ] F. Noether , [ 5 ] W.R. Dean , [ 6 ] Rosenhead , [ 7 ] Landau , [ 8 ] G.K. Batchelor [ 9 ] etc. A complete set of solutions was described by Edward Fraenkel in 1962. [ 10 ]
Consider two stationary plane walls with a constant volume flow rate Q {\displaystyle Q} is injected/sucked at the point of intersection of plane walls and let the angle subtended by two walls be 2 α {\displaystyle 2\alpha } . Take the cylindrical coordinate ( r , θ , z ) {\displaystyle (r,\theta ,z)} system with r = 0 {\displaystyle r=0} representing point of intersection and θ = 0 {\displaystyle \theta =0} the centerline and ( u , v , w ) {\displaystyle (u,v,w)} are the corresponding velocity components. The resulting flow is two-dimensional if the plates are infinitely long in the axial z {\displaystyle z} direction, or the plates are longer but finite, if one were neglect edge effects and for the same reason the flow can be assumed to be entirely radial i.e., u = u ( r , θ ) , v = 0 , w = 0 {\displaystyle u=u(r,\theta ),v=0,w=0} .
Then the continuity equation and the incompressible Navier–Stokes equations reduce to
The boundary conditions are no-slip condition at both walls and the third condition is derived from the fact that the volume flux injected/sucked at the point of intersection is constant across a surface at any radius.
The first equation tells that r u {\displaystyle ru} is just function of θ {\displaystyle \theta } , the function is defined as
Different authors defines the function differently, for example, Landau [ 8 ] defines the function with a factor 6 {\displaystyle 6} . But following Whitham , [ 11 ] Rosenhead [ 12 ] the θ {\displaystyle \theta } momentum equation becomes
Now letting
the r {\displaystyle r} and θ {\displaystyle \theta } momentum equations reduce to
and substituting this into the previous equation(to eliminate pressure) results in
Multiplying by F ′ {\displaystyle F'} and integrating once,
where C , D {\displaystyle C,D} are constants to be determined from the boundary conditions. The above equation can be re-written conveniently with three other constants a , b , c {\displaystyle a,b,c} as roots of a cubic polynomial, with only two constants being arbitrary, the third constant is always obtained from other two because sum of the roots is a + b + c = − 6 {\displaystyle a+b+c=-6} .
The boundary conditions reduce to
where R e = Q / ν {\displaystyle Re=Q/\nu } is the corresponding Reynolds number . The solution can be expressed in terms of elliptic functions . For convergent flow Q < 0 {\displaystyle Q<0} , the solution exists for all R e {\displaystyle Re} , but for the divergent flow Q > 0 {\displaystyle Q>0} , the solution exists only for a particular range of R e {\displaystyle Re} .
Source: [ 13 ]
The equation takes the same form as an undamped nonlinear oscillator(with cubic potential) one can pretend that θ {\displaystyle \theta } is time , F {\displaystyle F} is displacement and F ′ {\displaystyle F'} is velocity of a particle with unit mass, then the equation represents the energy equation( K . E . + P . E . = 0 {\displaystyle K.E.+P.E.=0} , where K . E . = 1 2 F ′ 2 {\displaystyle K.E.={\frac {1}{2}}F'^{2}} and P . E . = V ( F ) {\displaystyle P.E.=V(F)} ) with zero total energy, then it is easy to see that the potential energy is
where V ≤ 0 {\displaystyle V\leq 0} in motion. Since the particle starts at F = 0 {\displaystyle F=0} for θ = − α {\displaystyle \theta =-\alpha } and ends at F = 0 {\displaystyle F=0} for θ = α {\displaystyle \theta =\alpha } , there are two cases to be considered.
The rich structure of this dynamical interpretation can be found in Rosenhead (1940). [ 7 ]
For pure outflow, since F = a {\displaystyle F=a} at θ = 0 {\displaystyle \theta =0} , integration of governing equation gives
and the boundary conditions becomes
The equations can be simplified by standard transformations given for example in Jeffreys . [ 14 ]
where sn , cn {\displaystyle \operatorname {sn} ,\operatorname {cn} } are Jacobi elliptic functions .
The limiting condition is obtained by noting that pure outflow is impossible when F ′ ( ± α ) = 0 {\displaystyle F'(\pm \alpha )=0} , which implies b = 0 {\displaystyle b=0} from the governing equation. Thus beyond this critical conditions, no solution exists. The critical angle α c {\displaystyle \alpha _{c}} is given by
where
where K ( k 2 ) {\displaystyle K(k^{2})} is the complete elliptic integral of the first kind . For large values of a {\displaystyle a} , the critical angle becomes α c = 3 a K ( 1 2 ) = 3.211 a {\displaystyle \alpha _{c}={\sqrt {\frac {3}{a}}}K\left({\frac {1}{2}}\right)={\frac {3.211}{\sqrt {a}}}} .
The corresponding critical Reynolds number or volume flux is given by
where E ( k 2 ) {\displaystyle E(k^{2})} is the complete elliptic integral of the second kind . For large values of a , ( k 2 ∼ 1 2 − 3 2 a ) {\displaystyle a,\left(\ k^{2}\sim {\frac {1}{2}}-{\frac {3}{2a}}\right)} , the critical Reynolds number or volume flux becomes R e c = Q c ν = 12 a 3 [ E ( 1 2 ) − 1 2 K ( 1 2 ) ] = 2.934 a {\displaystyle Re_{c}={\frac {Q_{c}}{\nu }}=12{\sqrt {\frac {a}{3}}}\left[E\left({\frac {1}{2}}\right)-{\frac {1}{2}}K\left({\frac {1}{2}}\right)\right]=2.934{\sqrt {a}}} .
For pure inflow, the implicit solution is given by
and the boundary conditions becomes
Pure inflow is possible only when all constants are real c < b < 0 < a {\displaystyle c<b<0<a} and the solution is given by
where K ( k 2 ) {\displaystyle K(k^{2})} is the complete elliptic integral of the first kind .
As Reynolds number increases ( − b {\displaystyle -b} becomes larger), the flow tends to become uniform(thus approaching potential flow solution), except for boundary layers near the walls. Since m {\displaystyle m} is large and α {\displaystyle \alpha } is given, it is clear from the solution that K {\displaystyle K} must be large, therefore k ∼ 1 {\displaystyle k\sim 1} . But when k ≈ 1 {\displaystyle k\approx 1} , sn t ≈ tanh t , c ≈ b , a ≈ − 2 b {\displaystyle \operatorname {sn} t\approx \tanh t,\ c\approx b,\ a\approx -2b} , the solution becomes
It is clear that F ≈ b {\displaystyle F\approx b} everywhere except in the boundary layer of thickness O ( − b 2 ) {\displaystyle O\left({\sqrt {-{\frac {b}{2}}}}\right)} . The volume flux is Q / ν ≈ 2 α b {\displaystyle Q/\nu \approx 2\alpha b} so that | R e | = O ( | b | ) {\displaystyle |Re|=O(|b|)} and the boundary layers have classical thickness O ( | R e | 1 / 2 ) {\displaystyle O\left(|Re|^{1/2}\right)} . | https://en.wikipedia.org/wiki/Jeffery–Hamel_flow |
Jeffrey Robert Long is a professor of chemistry at the University of California, Berkeley known for his work in metal−organic frameworks and molecular magnetism . He was elected to the American Academy of Arts and Sciences in 2019 [ 1 ] and is the 2019 F. Albert Cotton Award recipient. His research interests include: the synthesis of inorganic clusters and porous materials, investigating the electronic and magnetic properties of inorganic materials; metal-organic frameworks, and gas storage/capture. [ 2 ]
Jeffrey Long was born in Rolla, Missouri on May 15, 1969. He is the son of Gary J. Long, Prof. Emeritus of Chemistry at the Missouri University of Science and Technology , an expert in Mössbauer spectroscopy . [ 3 ] He received his Bachelors of Arts from Cornell University in Chemistry ( summa cum laude ) and Mathematics ( cum laude ) in 1991. While an undergraduate student, he worked alongside Prof. Roald Hoffmann on the application of molecular orbital theory in determining solid-state band structure of metal carbides. [ 4 ] He went on to do graduate studies with Prof. Richard H. Holm at Harvard University where he studied the structure and electronic properties of transition metal chalcogenide clusters, earning his PhD in 1995. [ 5 ] After continuing with Richard Holm as a postdoctoral fellow, in 1996 he then went on to do post-doctoral studies with Prof. Paul Alivisatos at the University of California, Berkeley.
Long began his independent career at the University of California, Berkeley in 1997, where he expanded his work to include studies on Prussian blue analogs and metal cyanide coordination clusters with an emphasis on their magnetic properties. [ 6 ] He has contributed significantly to the field of molecular magnetism , most notably in the synthesis and characterization of a linear cobalt (II) complex exhibiting a non- Aufbau ground state, [ 7 ] the characterization of radical -bridged lanthanide single-molecule magnets (SMMs), [ 8 ] and the isolation of atomically defined 2-D metal-halide sheets within a porous material. [ 9 ] In the mid 2000s the focus of his research shifted towards the emergent field of Metal-Organic Frameworks (MOFs). His initial studies were focused on hydrogen storage in open-metal site manganese MOFs. [ 10 ] His other notable works in this field include the synthesis and characterization of novel frameworks for hydrocarbon separations, [ 11 ] the discovery of a novel cooperative mechanism for carbon dioxide capture , [ 12 ] as well as the discovery of materials for other industrially relevant chemical separations . [ 13 ] , [ 14 ] | https://en.wikipedia.org/wiki/Jeffrey_R._Long |
Jeffrey Skolnick is an American computational biologist . He is currently a Georgia Institute of Technology School of Biology Professor, the Director of the Center for the Study of Systems Biology , the Mary and Maisie Gibson Chair, the Georgia Research Alliance Eminent Scholar in Computational Systems Biology, the Director of the Integrative BioSystems Institute , and was previously the Scientific Advisor at Intellimedix. [ 1 ]
He has focused on the development of computational algorithms and their application to proteomes for the prediction of protein structure and function, the prediction of small molecule ligand-protein interactions with applications to drug discovery, the prediction of off-target uses of existing drugs, and the exploration of the interplay between protein physics and evolution in determining protein structure and function. He is a pioneer in the field of protein structure prediction, including the development of CABS and CAS methods of lattice based conformation sampling, and the algorithms Touchstone II and TASSER.
Skolnick is most known for demonstrating that the number of ligand binding pockets in proteins is quite small, thereby justifying the likelihood that large scale drug repurposing will work. This combined with the ability to use predicted as well as experimental structures in virtual ligand screening at higher accuracy and precision than existing approaches will enable FDA approved drugs with novel mechanisms of action to be identified computationally with a high likelihood of experimental success. [ 2 ] [ 3 ] [ 4 ]
He is also known for his unique teaching methodology and interactive pedagogy to simplify the comprehension of complex concepts in computational chemistry .
Skolnick was first to demonstrate that the library of single domain protein structures is likely complete and that the observed folds in nature arise from the confinement of dense polymer chains. He further demonstrated that the confinement of these dense polymer chains plus hydrodynamic interactions were the dominant contributor to diffusive processes in cells. Moreover, that the hydrodynamic interactions introduced large scale temporal and spatial correlations that may have important functional consequences. [ 2 ] [ 3 ] [ 5 ] [ 6 ]
He also pioneered the field of ligand homology modeling with his threading based, FINDSITE approach for protein function inference, binding site prediction and virtual ligand screening. The research showed that remotely related proteins identified by threading often share a common ligand binding site occupied by chemically similar ligands that contain strongly conserved anchor functional groups as well as a variable region that accounts for their binding specificity. These insights enable low-resolution predicted structures to be used for ligand screening/binding pose prediction, with comparable accuracy as with high-resolution experimental structures. In virtual ligand screening, the latest version, FINDSITEcomb, was shown to work far better than more traditional virtual screening approaches on both predicted and high resolution experimental structures. [ 7 ] [ 8 ]
He also developed the TASSER protein structure prediction approach, whose variants were among the top performers in CASP in the 2000s and the basis for the I-TASSER service. TASSER was among the first methods whose models were closer to the native structure than the starting template. [ 9 ] [ 10 ]
Skolnick's Ph.D. thesis " “Investigations on a Rod Like Polyelectrolyte Model", along with Fixman and Odijk, developed a theory for the electrostatic persistence length in polyelectrolytes now known as the Odijk-Skolnick-Fixman electrostatic persistence length which is still considered the classical benchmark. [ 11 ] [ 12 ]
Skolnick graduated summa cum laude from Washington University in 1975 with a Bachelor of Arts degree in chemistry. After Washington University, he moved on to Yale, where he graduated with a Master of Philosophy in Chemistry in 1977 and a Ph.D. in Chemistry just one year later in 1978.
His Ph.D. thesis, “Investigations on a Rod Like Polyelectrolyte Model”, focused on polymer statistical mechanics with Dr. Marshall Fixman. The methods described by Skolnick and Fixman and independently developed by Theo Odijk are still used as the basis for the electrostatic persistence length of polyelectrolytes. [ 11 ]
Skolnick has been recognized as a Fellow with the American Association for the Advancement of Science, the Biophysical Society, and the St. Louis Academy of Science. He has also been awarded an Alfred P. Sloan Research Fellowship. [ 13 ] [ 14 ] [ 15 ] [ 16 ]
He is also a cofounder of an early stage structural proteomics company, GeneFormatics, and his software has been commercialized by Tripos. [ 22 ] | https://en.wikipedia.org/wiki/Jeffrey_Skolnick |
Jeju Samdasoo ( Korean : 제주삼다수 ) is a brand of mineral water produced by Jeju province development corporation, manufactured by Kwangdong Pham. It is the only volcanic bedrock water in South Korea , and the plant is located in the Gyorae-ri, Jocheon-eup, Jeju City , Jeju Province . [ 1 ] The product has achieved annual certifications of U.S. FDA , Japan's Ministry of Health, Labor and Welfare, NSF , and ISO22000 (HACCP) . [ 1 ] Major exported regions are China, Japan, Indonesia, USA, Hong Kong and Saipan. [ 2 ]
In 1980s, while the private sale of bottled water was prohibited, Korean Air produced (and still continues to produce) Jeju water for in-aircraft. [ 3 ] As the sale of bottled water to the Koreans became possible in the 1990s, Jeju Province entered the mineral water market, motivated from the success of Korean Air. A development corporation was made and started to produce Jeju-water, and in 1998 Jeju Samdasoo was released. [ 3 ]
All of the Jeju-branded mineral water has been made by Jeju province development co. (except for Hanjin Jeju Pure Water ) since today.
Samdasoo is classed as soft water because its mineral content is generally low. [ 5 ]
Since Samdasoo was launched in March 1998, it has been ranked number one in Korea's bottled water market in six months. In 2009, the market share of drinking water PET bottles was 50.7%, [ 7 ] and by 2017 it was the market leader for 19 consecutive years. [ 8 ] [ 9 ] [ 10 ] It ranked first in market share for 20 consecutive years until 2018 [ 11 ]
Until now, Samdasoo has been 1st place in market share after it was released, but these days new brands of mineral water are appearing (especially Nongshim ), so market share of Samdasoo is decreasing. [ 12 ]
Water is raised from the volcanic bedrock which is located 420m underground, and Samdasoo is produced after a manufacturing process of "filtering - UV disinfection - injection - product inspection - packing - shipment". [ 13 ]
Since the release of Jeju Samdasoo, Nongshim and Jeju province development co. has made a trading base agreement of Samdasoo, and Jeju province development co. fulfilled the production while Nongshim took charge of sales activities. [ 14 ] But Jeju province revised the ordinance in December, 2011, and gave Nongsim a notice that the contract was canceled. Nongshim filed a suit against Jeju province development co., and Jeju province practically lost a case by the Supreme Court decision in June, 2016. But the selling right of Nongshim was already stopped, and the new seller Kwangdong Pharmaceutical has had the right since 2012. [ 14 ]
Jeju Samdasoo is said to offer discounts to customers who use delivery services through its application from May 12, 2021. "Jeju Samdasoo Club" not only offers benefits of more than annual fees, but also offers a variety of goods products as gifts. [ 15 ] | https://en.wikipedia.org/wiki/Jeju_Samdasoo |
Jellium , also known as the uniform electron gas ( UEG ) or homogeneous electron gas ( HEG ), is a quantum mechanical model of interacting free electrons in a solid where the complementary positive charges are not atomic nuclei but instead an idealized background of uniform positive charge density. This model allows one to focus on the effects in solids that occur due to the quantum nature of electrons and their mutual repulsive interactions (due to like charge) without explicit introduction of the atomic lattice and structure making up a real material. Jellium is often used in solid-state physics as a simple model of delocalized electrons in a metal, where it can qualitatively reproduce features of real metals such as screening , plasmons , Wigner crystallization and Friedel oscillations .
At zero temperature , the properties of jellium depend solely upon the constant electronic density . This property lends it to a treatment within density functional theory ; the formalism itself provides the basis for the local-density approximation to the exchange-correlation energy density functional.
The term jellium was coined by Conyers Herring in 1952, alluding to the "positive jelly" background, and the typical metallic behavior it displays. [ 1 ]
The jellium model treats the electron-electron coupling rigorously. The artificial and structureless background charge interacts electrostatically with itself and the electrons. The jellium Hamiltonian for N electrons confined within a volume of space Ω, and with electronic density ρ ( r ) and (constant) background charge density n ( R ) = N /Ω is [ 2 ] [ 3 ]
H ^ = H ^ e l + H ^ b a c k + H ^ e l − b a c k , {\displaystyle {\hat {H}}={\hat {H}}_{\mathrm {el} }+{\hat {H}}_{\mathrm {back} }+{\hat {H}}_{\mathrm {el-back} },}
where
H back is a constant and, in the limit of an infinite volume, divergent along with H el-back . The divergence is canceled by a term from the electron-electron coupling: the background interactions cancel and the system is dominated by the kinetic energy and coupling of the electrons. Such analysis is done in Fourier space; the interaction terms of the Hamiltonian which remain correspond to the Fourier expansion of the electron coupling for which q ≠ 0 .
The traditional way to study the electron gas is to start with non-interacting electrons which are governed only by the kinetic energy part of the Hamiltonian, also called a Fermi gas . The kinetic energy per electron is given by
where E F {\displaystyle E_{\rm {F}}} is the Fermi energy, k F {\displaystyle k_{\rm {F}}} is the Fermi wave vector, and the last expression shows the dependence on the Wigner–Seitz radius r s ′ {\displaystyle r'_{\rm {s}}} where energy is measured in rydbergs . a 0 {\displaystyle a_{0}} is the Bohr radius . In what follows r s {\displaystyle r_{\rm {s}}} is the normalized value r s = r s ′ / a 0 {\displaystyle r_{\rm {s}}=r'_{\rm {s}}/a_{0}}
Without doing much work, one can guess that the electron-electron interactions will scale like the inverse of the average electron-electron separation and hence as 1 / r 12 {\displaystyle 1/r_{12}} (since the Coulomb interaction goes like one over distance between charges) so that if we view the interactions as a small correction to the kinetic energy, we are describing the limit of small r s {\displaystyle r_{\rm {s}}} (i.e. 1 / r s 2 {\displaystyle 1/r_{\rm {s}}^{2}} being larger than 1 / r s {\displaystyle 1/r_{\rm {s}}} ) and hence high electron density. Unfortunately, real metals typically have r s {\displaystyle r_{\rm {s}}} between 2-5 which means this picture needs serious revision.
The first correction to the free electron model for jellium is from the Fock exchange contribution to electron-electron interactions. Adding this in, one has a total energy of
where the negative term is due to exchange: exchange interactions lower the total energy. Higher order corrections to the total energy are due to electron correlation and if one decides to work in a series for small r s {\displaystyle r_{s}} , one finds
The series is quite accurate for small r s {\displaystyle r_{\rm {s}}} but of dubious value for r s {\displaystyle r_{\rm {s}}} values found in actual metals.
For the full range of r s {\displaystyle r_{\rm {s}}} , Chachiyo's correlation energy density can be used as the higher order correction. In this case,
The physics of the zero-temperature phase behavior of jellium is driven by competition between the kinetic energy of the electrons and the electron-electron interaction energy. The kinetic-energy operator in the Hamiltonian scales as 1 / r s 2 {\displaystyle 1/r_{\rm {s}}^{2}} , where r s {\displaystyle r_{\rm {s}}} is the Wigner–Seitz radius , whereas the interaction energy operator scales as 1 / r s {\displaystyle 1/r_{\rm {s}}} . Hence the kinetic energy dominates at high density (small r s {\displaystyle r_{\rm {s}}} ), while the interaction energy dominates at low density (large r s {\displaystyle r_{\rm {s}}} ).
The limit of high density is where jellium most resembles a noninteracting free electron gas . To minimize the kinetic energy, the single-electron states are delocalized, in a state very close to the Slater determinant (non-interacting state) constructed from plane waves. Here the lowest-momentum plane-wave states are doubly occupied by spin-up and spin-down electrons, giving a paramagnetic Fermi fluid.
At lower densities, where the interaction energy is more important, it is energetically advantageous for the electron gas to spin-polarize (i.e., to have an imbalance in the number of spin-up and spin-down electrons), resulting in a ferromagnetic Fermi fluid. This phenomenon is known as itinerant ferromagnetism . At sufficiently low density, the kinetic-energy penalty resulting from the need to occupy higher-momentum plane-wave states is more than offset by the reduction in the interaction energy due to the fact that exchange effects keep indistinguishable electrons away from one another.
A further reduction in the interaction energy (at the expense of kinetic energy) can be achieved by localizing the electron orbitals. As a result, jellium at zero temperature at a sufficiently low density will form a so-called Wigner crystal , in which the single-particle orbitals are of approximately Gaussian form centered on crystal lattice sites. Once a Wigner crystal has formed, there may in principle be further phase transitions between different crystal structures and between different magnetic states for the Wigner crystals (e.g., antiferromagnetic to ferromagnetic spin configurations) as the density is lowered. When Wigner crystallization occurs, jellium acquires a band gap .
Within Hartree–Fock theory, the ferromagnetic fluid abruptly becomes more stable than the paramagnetic fluid at a density parameter of r s = 5.45 {\displaystyle r_{\rm {s}}=5.45} in three dimensions (3D) and 2.01 {\displaystyle 2.01} in two dimensions (2D). [ 5 ] However, according to Hartree–Fock theory, Wigner crystallization occurs at r s = 4.5 {\displaystyle r_{\rm {s}}=4.5} in 3D and 1.44 {\displaystyle 1.44} in 2D, so that jellium would crystallise before itinerant ferromagnetism occurs. [ 6 ] Furthermore, Hartree–Fock theory predicts exotic magnetic behavior, with the paramagnetic fluid being unstable to the formation of a spiral spin-density wave. [ 7 ] [ 8 ] Unfortunately, Hartree–Fock theory does not include any description of correlation effects, which are energetically important at all but the very highest densities, and so a more accurate level of theory is required to make quantitative statements about the phase diagram of jellium.
Quantum Monte Carlo (QMC) methods, which provide an explicit treatment of electron correlation effects, are generally agreed to provide the most accurate quantitative approach for determining the zero-temperature phase diagram of jellium. The first application of the diffusion Monte Carlo method was Ceperley and Alder's famous 1980 calculation of the zero-temperature phase diagram of 3D jellium. [ 9 ] They calculated the paramagnetic-ferromagnetic fluid transition to occur at r s = 75 ( 5 ) {\displaystyle r_{s}=75(5)} and Wigner crystallization (to a body-centered cubic crystal) to occur at r s = 100 ( 20 ) {\displaystyle r_{\rm {s}}=100(20)} . Subsequent QMC calculations [ 10 ] [ 11 ] have refined their phase diagram: there is a second-order transition from a paramagnetic fluid state to a partially spin-polarized fluid from r s = 50 ( 2 ) {\displaystyle r_{\rm {s}}=50(2)} to about 100 {\displaystyle 100} ; and Wigner crystallization occurs at r s = 106 ( 1 ) {\displaystyle r_{\rm {s}}=106(1)} .
In 2D, QMC calculations indicate that the paramagnetic fluid to ferromagnetic fluid transition and Wigner crystallization occur at similar density parameters, in the range 30 < r s < 40 {\displaystyle 30<r_{\rm {s}}<40} . [ 12 ] [ 13 ] The most recent QMC calculations indicate that there is no region of stability for a ferromagnetic fluid. [ 14 ] Instead there is a transition from a paramagnetic fluid to a hexagonal Wigner crystal at r s = 31 ( 1 ) {\displaystyle r_{\rm {s}}=31(1)} . There is possibly a small region of stability for a (frustrated) antiferromagnetic Wigner crystal, before a further transition to a ferromagnetic crystal. The crystallization transition in 2D is not first order, so there must be a continuous series of transitions from fluid to crystal, perhaps involving striped crystal/fluid phases. [ 15 ] Experimental results for a 2D hole gas in a GaAs/AlGaAs heterostructure (which, despite being clean, may not correspond exactly to the idealized jellium model) indicate a Wigner crystallization density of r s = 35.1 ( 9 ) {\displaystyle r_{\rm {s}}=35.1(9)} . [ 16 ]
Jellium is the simplest model of interacting electrons. It is employed in the calculation of properties of metals, where the core electrons and the nuclei are modeled as the uniform positive background and the valence electrons are treated with full rigor. Semi-infinite jellium slabs are used to investigate surface properties such as work function and surface effects such as adsorption ; near surfaces the electronic density varies in an oscillatory manner, decaying to a constant value in the bulk. [ 17 ] [ 18 ] [ 19 ]
Within density functional theory , jellium is used in the construction of the local-density approximation , which in turn is a component of more sophisticated exchange-correlation energy functionals. From quantum Monte Carlo calculations of jellium, accurate values of the correlation energy density have been obtained for several values of the electronic density, [ 9 ] which have been used to construct semi-empirical correlation functionals. [ 20 ]
The jellium model has been applied to superatoms , metal clusters , octacarbonyl complexes , and used in nuclear physics . | https://en.wikipedia.org/wiki/Jellium |
Jelly-falls are marine carbon cycling events whereby gelatinous zooplankton , primarily cnidarians , sink to the seafloor and enhance carbon and nitrogen fluxes via rapidly sinking particulate organic matter . [ 1 ] These events provide nutrition to benthic megafauna and bacteria . [ 2 ] [ 3 ] Jelly-falls have been implicated as a major “gelatinous pathway” for the sequestration of labile biogenic carbon through the biological pump . [ 4 ] These events are common in protected areas with high levels of primary production and water quality suitable to support cnidarian species. These areas include estuaries and several studies have been conducted in fjords of Norway . [ 3 ]
Jelly-falls are primarily made up of the decaying corpses of Cnidaria and Thaliacea ( Pyrosomida , Doliolida , and Salpida ). [ 1 ] Several circumstances can trigger the death of gelatinous organisms which would cause them to sink. These include high levels of primary production that can clog the feeding apparatuses of the organisms, a sudden temperature change, when an old bloom runs out of food, when predators damage the bodies of the jellies, and parasitism . [ 5 ] In general, however, jelly-falls are linked to jelly-blooms and primary production, with over 75% of the jelly falls in subpolar and temperate regions occurring after spring blooms, and over 25% of the jelly-falls in the tropics occurring after upwelling events . [ 1 ]
With global climates shifting towards creating warmer and more acidic oceans, conditions not favored by non-resilient species, jellies are likely to grow in population sizes. Eutrophic areas and dead zones can become jelly hot spots with substantial blooms. [ 6 ] As the climate changes and ocean waters warm, jelly blooms become more prolific and the transport of jelly-carbon to the lower ocean increases. [ 7 ] With a possible slowing of the classic biological pump, the transport of carbon and nutrients to the deep sea through jelly-falls may become more and more important to deep ocean. [ 8 ]
The decomposition process starts after death and can proceed in the water column as the gelatinous organisms are sinking. [ 5 ] Decay happens faster in the tropics than in temperate and subpolar waters as a result of warmer temperatures. [ 5 ] In the tropics, a jelly-fall may take less than 2 days to decay in warmer, surface water, but as many as 25 days when it is lower than 1000 m deep. [ 5 ] However, lone gelatinous organisms may spend less time on the sea floor as one study found that jellies could be decomposed by scavengers in the Norwegian deep sea in under two and a half hours. [ 9 ]
Decomposition of jelly-falls is largely aided by these kinds of scavengers . In general, echinoderms , such as sea stars , have emerged as the primary consumer of jelly-falls, followed by crustaceans and fish. [ 1 ] However, which scavengers find their way to jelly-falls is highly reliant on each ecosystem. For example, in an experiment in the Norwegian deep sea, hagfish were the first scavengers to find the traps of decaying jellies, followed by squat lobsters , and finally decapod shrimp. [ 9 ] Photographs taken off the coast of Norway on natural jelly-falls also revealed caridean shrimp feeding on jelly carcasses. [ 3 ]
With increased populations and blooms becoming more common, with favorable conditions and a lack of other filter feeders in the area to consume plankton , environments with jellies present will have carbon pumps be more primarily supplied with jelly-falls. This could lead to issues of habitats with established biological pumps succumbing to nonequilibrium as the presence of jellies would change the food web as well as changes to the amount of carbon deposited into the sediment. [ 10 ] Finally, decomposition is aided by the microbial community. In a case study on the Black Sea , the number of bacteria increased in the presence of jelly-falls, and the bacteria were shown to preferentially use nitrogen released from decaying jelly carcasses while mostly leaving carbon. [ 11 ] In a study conducted by Andrew Sweetman in 2016, it was discovered using core samples of the sediment in Norwegian fjords , the presence of jelly-falls significantly impacted the biochemical process of these benthic communities. Bacteria consume jelly carcasses rapidly, removing opportunities of acquiring sustenance for bottoming feeding macrofauna , which has impacts traveling up the trophic levels. [ 12 ] In addition, with the exclusion of scavengers, jelly-falls develop a white layer of bacteria over the decaying carcasses and emit a black residue over the surrounding area, which is from sulfide. [ 13 ] This high level of microbial activity requires a lot of oxygen, which can lead zones around jelly-falls to become hypoxic and inhospitable to larger scavengers. [ 13 ] By providing abundant nutrients and surfaces for bacterial colonization and interactions, jelly-falls can also be hotspots for the transmission of antimicrobial resistance genes among marine bacterial communities. [ 14 ]
Researching jelly-falls relies on direct observational data such as video, photography, or benthic trawls . [ 1 ] A complication with trawling for jelly-falls is the gelatinous carcass easily falls apart and as a result, opportunistic photography, videography, and chemical analysis have been primary methods of monitoring. [ 3 ] [ 9 ] This means that jelly-falls are not always observed in the time period in which they exist. Because jelly-falls can be fully processed and degraded within a number of hours by scavengers [ 9 ] and the fact that some jelly-falls will not sink below 500 m in tropical and subtropical waters, [ 5 ] the importance and prevalence of jelly-falls may be underestimated. | https://en.wikipedia.org/wiki/Jelly-falls |
Jemma Redmond (16 March 1978 – 16 August 2016) was an Irish biotechnology pioneer and innovator. She was a co-founder of 3D bio-printing firm Ourobotics, developers of the first-ever ten-material bio-printer. [ 1 ] Redmond designed a way of keeping living cells alive while printed using 3D printers, [ 2 ] making her a leading figure in Irish science and technology. [ 1 ]
Born in Tallaght , South Dublin, Redmond studied electronic engineering before earning her undergraduate degree in applied physics at Robert Gordon University in Aberdeen in 2002. She later returned to university, completing a master's degree in nano-bioscience at University College Dublin in 2012, along with qualifications in project management and electronic engineering. [ 2 ] Her interest in nano-bioscience was sparked by an intersex condition that made her infertile. [ 2 ] [ 3 ] [ 4 ] She started bioprinting by building her own devices in her kitchen. [ 5 ]
A serial entrepreneur, Redmond created a company manufacturing vending machines in 2008, before co-founding Ourobotics in January 2015, with Alanna Kelly from Galway, Ireland, and backing from SOSV . [ 6 ] Kelly resigned as director in July 2015. Tony Herbert, entrepreneur and owner of technical optics company Irish Precision Optics, from Cork became a director of Ourobotics in August 2015 and the company moved to the optics company premises in Cork City. Redmond designed and marketed two bio-printers including, in 2016, a printer capable of printing human tissue, [ 6 ] and at a much lower cost than previous bio-printers. [ 2 ] Redmond's first device printed an extended finger , described by Pádraig Belton as "a gentle reply to those who had called printing organs of such complexity impossible." [ 2 ]
In January 2016, the company won first prize in a prestigious international competition, Silicon Valley Open Doors Europe . [ 7 ] [ 8 ] [ 9 ] The company was also selected as part of a start-up adoption program by Google. [ 10 ]
Redmond died unexpectedly in August 2016. [ 1 ] [ 2 ] [ 11 ] Her mother described it as a "tragic accident". [ 12 ] She was described as a polymath, [ 1 ] an inspiration and great friend. [ 7 ] [ 13 ] She was survived by her partner, Kay Cairns, a journalist and activist. [ 14 ] | https://en.wikipedia.org/wiki/Jemma_Redmond |
In chemistry , the Jemmis mno rules represent a unified rule for predicting and systematizing structures of compounds , usually clusters . The rules involve electron counting. They were formulated by E. D. Jemmis to explain the structures of condensed polyhedral boranes such as B 20 H 16 , which are obtained by condensing polyhedral boranes by sharing a triangular face, an edge, a single vertex, or four vertices. These rules are additions and extensions to Wade's rules and polyhedral skeletal electron pair theory . [ 1 ] [ 2 ] The Jemmis mno rule provides the relationship between polyhedral boranes, condensed polyhedral boranes, and β-rhombohedral boron. [ 3 ] [ 4 ] This is similar to the relationship between benzene , condensed benzenoid aromatics , and graphite , shown by Hückel's 4 n + 2 rule , as well as the relationship between tetracoordinate tetrahedral carbon compounds and diamond . The Jemmis mno rules reduce to Hückel's rule when restricted to two dimensions and reduce to Wade's rules when restricted to one polyhedron. [ 5 ]
Electron-counting rules are used to predict the preferred electron count for molecules. The octet rule , the 18-electron rule , and Hückel's 4 n + 2 pi-electron rule are proven to be useful in predicting the molecular stability. Wade's rules were formulated to explain the electronic requirement of monopolyhedral borane clusters. The Jemmis mno rules are an extension of Wade's rules, generalized to include condensed polyhedral boranes as well.
The first condensed polyhedral borane, B 20 H 16 , is formed by sharing four vertices between two icosahedra . According to Wade's n + 1 rule for n -vertex closo structures, B 20 H 16 should have a charge of +2 ( n + 1 = 20 + 1 = 21 pairs required; 16 BH units provide 16 pairs; four shared boron atoms provide 6 pairs; thus 22 pairs are available). To account for the existence of B 20 H 16 as a neutral species, and to understand the electronic requirement of condensed polyhedral clusters, a new variable, m , was introduced and corresponds to the number of polyhedra (sub-clusters). [ 6 ] In Wade's n + 1 rule, the 1 corresponds to the core bonding molecular orbital (BMO) and the n corresponds to the number of vertices, which in turn is equal to the number of tangential surface BMOs. If m polyhedra condense to form a macropolyhedron, m core BMOs will be formed. Thus the skeletal electron pair (SEP) requirement of closo-condensed polyhedral clusters is m + n .
Single-vertex sharing is a special case where each subcluster needs to satisfy Wade's rule separately. Let a and b be the number of vertices in the subclusters including the shared atom. The first cage requires a + 1 and the second cage requires b + 1 SEPs. Therefore, a total of a + b + 2 or a + b + m SEPs are required; but a + b = n + 1, as the shared atom is counted twice. The rule can be modified to m + n + 1, or generally m + n + o , where o corresponds to the number of single-vertex sharing condensations. The rule can be made more general by introducing a variable, p , corresponding to the number of missing vertices, and q , the number of caps. As such, the generalized Jemmis rule can be stated as follows:
m + n + o + p − q = 2 + 20 + 0 + 0 + 0 = 22 SEPs are required; 16 BH units provide 16 pairs; four shared boron atoms provide 6 pairs, which describes why B 20 H 16 is stable as a neutral species. [ 7 ]
closo - B 21 H − 18 is formed by the face-sharing condensation of two icosahedra. The m + n + o + p − q rule demands 23 SEPs; 18 BH units provide 18 pairs and 3 shared boron atoms provide 4 + 1 ⁄ 2 pairs; the negative charge provides one half pair. [ 8 ]
The bis- nido - B 12 H 16 is formed by the edge-sharing condensation of a nido - B 8 unit and a nido - B 6 unit. The m + n + o + p − q count of 16 SEPs are satisfied by ten BH units which provide 10 pairs, two shared boron atoms which provide 3 pairs, and six bridging H atoms which provide 3 pairs. [ 7 ]
m + n + o + p − q = 26 SEPs. A transition metal with n valence electrons provides n − 6 electrons for skeletal bonding as 6 electrons occupying the metal-like orbitals do not contribute much to the cluster bonding. Therefore Cu provides 2 + 1 ⁄ 2 pairs, 22 BH units provide 22 pairs; three negative charges provide 1 + 1 ⁄ 2 pairs. [ 7 ]
According to the m + n + o + p − q rule, ferrocene requires 2 + 11 + 1 + 2 − 0 = 16 SEPs. 10 CH units provide 15 pairs while Fe provides one pair. [ 7 ]
B 18 H 2− 20 is a bis- nido edge-shared polyhedron. Here, m + n + o + p − q = 2 + 18 + 0 + 2 − 0 = 22; 16 BH units provide 16 pairs, 4 bridging hydrogen atoms provide 2 pairs, two shared boron atoms provide 3 pairs, along with the two negative charges which provide 1 pair. [ 7 ]
Triple-decker complexes are known to obey a 30-valence electron (VE) rule. Subtracting 6 pairs of nonbonding electrons from the two metal atoms brings the number of SEPs to 9 pairs. For a triple-decker complex with C 5 H 5 as the decks, m + n + o + p − q = 3 + 17 + 2 + 2 − 0 = 24. Subtracting the 15 pairs corresponding to C–C sigma bonds , it becomes 9 pairs. For example, consider (C 5 (CH 3 ) 5 ) 3 Ru + 2 : 15 C–CH 3 groups provide 22 + 1 ⁄ 2 pairs. Each ruthenium atom provides one pair. Removing the electron corresponding to the positive charge of the complex leads to a total of 22 + 1 ⁄ 2 + 2 − 1 ⁄ 2 = 24 pairs.
The structure of β-rhombohedral boron is complicated by the presence of partial occupancies and vacancies. [ 9 ] [ 10 ] [ 11 ] The idealized unit cell, B 105 has been shown to be electron-deficient and hence metallic according to theoretical studies, but β-boron is a semiconductor. [ 12 ] Application of the Jemmis rule shows that the partial occupancies and vacancies are necessary for electron sufficiency.
B 105 can be conceptually divided into a B 48 fragment and a B 28 −B−B 28 ( B 57 ) fragment. According to Wade's rule, the B 48 fragment requires 8 electrons (the icosahedron at the centre (green) requires 2 electrons; each of the six pentagonal pyramids (black and red) completes an icosahedron in the extended structure; as such the electronic requirement for each of them is 1). The B 28 −B−B 28 or B 57 is formed by the condensation of 6 icosahedra and two trigonal bipyramids . Here, m + n + o + p − q = 8 + 57 + 1 + 0 − 0 = 66 pairs required for stability, but 67 + 1 ⁄ 2 are available. Therefore the B 28 −B−B 28 fragment has 3 excess electrons and the idealized B105 is missing 5 electrons. The 3 excess electrons in the B 28 −B−B 28 fragment can be removed by removing one B atom, which leads to B 27 −B−B 28 ( B 56 ). The requirement of 8 electrons by the B 48 fragment can be satisfied by 2 + 2 ⁄ 3 boron atoms and the unit cell contains 48 + 56 + 2 + 2 ⁄ 3 = 106 + 2 ⁄ 3 , which is very close to the experimental result. [ 3 ] | https://en.wikipedia.org/wiki/Jemmis_mno_rules |
The Jena Declaration is a scientific statement that questions and refutes the concept of human " races in a biological sense ". It was published in September 2019 at the 112th Annual Meeting of the German Zoological Society (Deutsche Zoologische Gesellschaft) in Jena. The statement was written by leading scientists from the fields of evolutionary research , genetics and zoology , and was instrumental in influencing the legislative amendment to remove the term "Rasse" (roughly "race in a biological sense") from the German constitution . [ 1 ] [ 2 ] [ 3 ] With this statement, the Institute for Zoology and Evolutionary Research at Friedrich Schiller University Jena explicitly distances itself from its 20th century predecessors, especially from the controversial scholar and evolutionary biologist Ernst Haeckel , who was closely associated with the University of Jena and whose ideas of racism and eugenics are today considered scientifically untenable and morally reprehensible. [ 4 ]
The authors of the statement, Martin S. Fischer , Uwe Hoßfeld , Johannes Krause and Stefan Richter examined the issue of alleged human " races " from a biological perspective. They clarified that this concept has no scientific justification. Scientific studies of genetic variation within and between human populations showed that the biological concept of "race" was a typological construct based on arbitrarily selected physical characteristics and did not reflect the actual genetic diversity of the human species. [ 5 ]
The Jena Declaration affirms that there are no "races" in the biological sense in humans, since the genetic variation within human populations is often greater than the genetic variation between these populations. Only in domestic animals the genetic similarity within a breed is actually greater than between breeds. Moreover, genetic differences between populations are continuous, as humans travelled long before major explorations and voyages of conquest by Europeans, creating links between populations that were geographically distant from each other. External characteristics such as skin colour , used for typological classifications or in everyday racism, are very superficial and rapidly changing biological adaptations to local conditions. In the human genome , for example, there is not a single difference among the 3.2 billion base pairs that separates Africans from non-Africans. So not only is there not a single gene that accounts for "racial" differences, there is not even a single base pair . [ 5 ]
The authors conclude that the concept of human "races" is the result of racism and not its precondition. Its use in scientific literature and social discourse often leads to misunderstandings and reinforces prejudice and discrimination. They therefore call for the term "race" to be discontinued in relation to people, except in historical or socio-political contexts where it should be understood as a social construction rather than a biological reality . They argue that the use of the term in relation to people creates a false idea of genetically separate groups and that it is important to debunk this myth in order to combat racism.
They conclude the statement with an appeal to educational institutions , media , authorities and all citizens to reconsider the German term "Rasse" and emphasise genetic diversity and humanity instead of artificial and harmful categorisations.
In Germany, the Declaration had a considerable impact on public debate and legislation , especially on the discussion about removing the term "Rasse" from the German constitution. [ 1 ] [ 3 ]
The Jena Declaration also led to a number of publications in the field of education and learning . In the book "Den Begriff 'Rasse' überwinden: die 'Jenaer Erklärung' in der (Hoch-)Schulbildung" (Overcoming the Concept of Race: The Jena Declaration in (Higher) School Education), [ 6 ] a variety of ideas and concepts for overcoming the concept of "race" are offered. In this publication, the Jena Declaration serves as an impulse for a nationwide reorientation of (high) school education. Another example is the publication "Die Jenaer Erklärung gegen Rassismus' und ihre Anwendung im Unterricht" (The Jena Declaration against Racism and its Application in the Classroom), [ 7 ] which presents concrete examples of the application of the Jena Declaration in the classroom.
IQWiG (The independent Institute for Quality and Efficiency in Health Care) also backs the "Jena Declaration" by ceasing to translate the term "race" as "Rasse" in its evaluations. [ 8 ]
The Institute no longer translates the term "race" as "Rasse" in its assessments. | https://en.wikipedia.org/wiki/Jena_Declaration |
Jennifer Pietenpol is Chief Scientific and Strategic Officer, Executive Vice-President for Research, and the Ingram Professor of Cancer Research at Vanderbilt University Medical Center . [ 1 ] Pietenpol additionally serves as the Chief Scientific Advisor to the Susan G. Komen Foundation for breast cancer. [ 2 ]
Pietenpol's early research focused on the signaling of the p53 gene within the breast cancer family, specifically Triple Negative Breast Cancer . [ 3 ] [ 4 ] [ 5 ] Pietenpol used a combined approach of bioinformatics and genetics to make discoveries on the signaling behavior of the p53 gene family. [ 6 ] [ 7 ]
Pietenpol serves as an elected fellow of the American Association for the Advancement of Science (2012) and the American Association for Cancer Research Academy (2022). [ 3 ] In 2008 she was appointed by President George Bush to serve on the National Cancer Advisory Board for the National Cancer Institute. [ 8 ] In 2016 she was selected to serve on then Vice-President Joe Biden's National Cancer Moonshot Program 's Blue Ribbon Panel. [ 9 ] [ 10 ]
Pietenpol studied biology at Carleton College , where she now [ when? ] serves on the board of trustees. [ 11 ] She was a student athlete and still holds some of Carleton's volleyball and track and field team records. [ 12 ] [ 13 ] She received her PhD in cell biology at Vanderbilt University School of Medicine in 1990. [ 14 ] She was a postdoc fellow at Johns Hopkins School of Medicine . She was an assistant professor of Biochemistry at Vanderbilt from 1994. [ 15 ]
Pietenpol and her research group have developed techniques for analysis of p53 and p53 family member chromatin binding and identification of p53 family target genes. [ 16 ] [ 17 ] [ 18 ] Her team is also responsible for delineating p73 binding sites within the mammal the genome and the discovery that p73 , another mammal protein gene, is required for ovarian folliculogenesis, multiciliogenesis, and certain regulation of the Foxj1-associated genes within mammals. [ 19 ] [ 20 ]
Her team successfully classified TNBC into 4 molecular subtypes―basal-like 1 (BL1), basal-like 2 (BL2), mesenchymal (M), and luminal androgen receptor (LAR). This was performed by the integration of molecular genomic techniques with bioinformatics, a tenant of Pietenpol's work. [ 21 ] [ 22 ] [ 23 ]
Recently, she and her team has focused on better understanding LAR TNBC, which is a rare subtype of TNBC that expresses androgen receptors , making it difficult to clinically treat. [ 24 ] [ 25 ]
Pietenpol has published over 250 scientific papers, which have been cited nearly 20,000 times, in journals including Nature , Cell , Cancer Research , and The Journal of Clinical Investigation . [ 26 ] [ 27 ] | https://en.wikipedia.org/wiki/Jennifer_Pietenpol |
Jennifer L. M. Rupp FRSC (born January 27, 1980) is a material scientist and professor at the Technical University of Munich , visiting professor at the Massachusetts Institute of Technology and the CTO for battery research at TUM International Energy Research. Rupp has published more than 130 papers in peer reviewed journals, co-authored 7 book chapters and holds more than 25 patents. Rupp research broadly encompasses solid state materials and cell designs for sustainable batteries , energy conversion and neuromorphic memory and computing.
Rupp was born in Germany in 1980 [ 1 ] and grew up from her youth years in Vienna Austria . Her mother is a language teacher and her father is a physicist, the family is mixed French-German-Italian. [ 2 ] She played competitive piano as a child and struggled to choose between pursuing her love for music and natural sciences. [ 2 ] Rupp was active in her teen years in an environmental chemistry group and also an Austrian team member competing internationally at the International Young Physicist Team, where they won 3d place in 1998.
Rupp received a Master of Natural Science Degree at the University of Vienna [ 1 ] followed by a doctoral degree at ETH Zurich . Her undergraduate efforts were recognised by the Austrian Chemical Society , who presented her with their prize for her diploma thesis. [ 3 ] She was awarded the ETH Zurich medal for PhD excellence [ 3 ] for her thesis on micro-Solid Oxide Fuel Cells and functional ceramic materials under the supervision of Ludwig Gauckler at ETH Zurich .
Rupp was appointed a postdoc and group leader working at ETH Zurich till 2010, where she studied solid state ionic conductors and conceptualized on micro-solid-oxide fuel cell devices. [ 1 ] In 2011 she joined the National Institute for Materials Science in Tsukuba Japan, where she learned how to make oxide memristors for non-volatile memory concepts and protonic fuel cells. [ 1 ] She left early as a consequence of the Fukushima Daiichi nuclear disaster [ 2 ] and relocated in 2011 with her family to the USA where she joined as a senior scientist the Massachusetts Institute of Technology . In 2012 she was awarded a prestigious Swiss National Science Foundation professorship career grant as a non-tenure track professor at ETH Zurich intensifying her research on memristive effects and starting also on solar-to-fuel conversion materials. In 2015 she received the ERC Starting grant (backed up in this year by SNSF ) as a 2nd career grant to foster more research on materials for neuromorphic computing and memories. [ 4 ] Short after in 2017, Rupp joined as a faculty at Massachusetts Institute of Technology , where she went through the promotion from assistant to associate professor. At MIT her prime appointment was in the department of material science and engineering and she was also appointed at the electrical engineering and computer science department . In her research at MIT, she focussed intensively with her team on solid state batteries , electroceramics and the concept of Lithionics to use Li-ions beyond batteries in solids state devices to neuromorphically compute, sense or react on optical stimulation.
In fall 2021, Rupp joined as professor at Technical University of Munich keeping an appointment as visiting professor at Massachusetts Institute of Technology , as well as accepting the roles of new CTO for battery research at TUM International Energy Research. In 2023, she Co-Founded and serves as CSO of QKera GmbH, a German solid electrolyte material producer targeting inexpensive, sinter-free, low CO 2 footprint solid chemistries. [ 5 ]
Rupp serves on various advisory boards of companies with businesses on batteries or electroceramic manufacture, is an appointed Academic Director at the TUM Venture Labs to support rapid tech transfer, and is an elected Advisory Board Member of academic journals like Energy & Environmental Science , Advanced Energy Materials , Advanced Functional Materials and others. Since 2017, she is a multiple-times reelected Associate Editor at the Journal of Materials Chemistry A . [ 6 ]
In 2019, she founded the LILA Mentorship program for Minorities in Engineering and Sciences in an effort to bridge the ever-existing gender gap, support minority groups and foster diversity in future leadership in energy and solid-state chemistry/material R&D.
Battery research
Rupp is developing next-generation batteries for application in electric vehicles and portable electronics, focusing on novel material synthesis and cell designs. Her research contributes to safer Li-conducting solid-electrolyte alternatives to classic polymers for lithium-ion solid and hybrid batteries by pioneering innovative solid-state synthesis chemistries like the sequential deposition synthesis in collaboration with Samsung , effects and structure science. She has also made major contributions in developing battery ceramic synthesis routes for thin electrolyte compounds, contribute to interface engineering electrode-electrode designs and structural design of various electrolyte and electrode chemistries. She talks about battery research in the Battery generation Podcast, [ 7 ] which reaches ++105000 times watches in short time.
Lithionic research
In her Lithionic research, she has developed one of the key papers discussing structure-property requirements of Li-based solid state materials to execute Lithionic functions to neuromorphically compute, sense or react on optical stimuli beyond battery applications. The work lead to a larger research consortium funded by Ericsson to foster the tech for 6G at MIT and was initiated and led by Rupp. In the quest of having less materials serving more functions for future devices she contributes with material concepts, chemistry and physical operations to execute additional functions beyond classic energy storage.
Solid state ionics and electronics research & device engineering
The theme of solid state ionics and electronics is deeply centered in Rupp's work. Her objectives are to create tailored solid state materials and electroceramics for energy conversion and storage or information computing. This includes material design and fundamental model experiments on electro-chemo-mechanics for ionic conductors (i.e. with strain modulus) or also recent work with her colleague Harry Tuller (MIT) and students on opto-ionics. Applications of fast ion conductors include fuel cells, sensors, batteries, memristors, or neuromorphic computing chips. Several proof-of-concept devices and electrochemical operation principles stem from Rupp's team such as strained memristors, or recently proposed glucose-converting fuel cell chips for human implants.
Industrial collaboration, support and consultancy
Rupp has collaborated, served as a consultant to or received competitive awards from several companies including BMW , Samsung , Ericsson , Shell , Equinor , Alkegen, Unifrax, SiFab, Sensirion, Eni , Merck , BASF , Volkswagen ,Oerlikon and NGK/NTK. | https://en.wikipedia.org/wiki/Jennifer_Rupp |
Jenny Zhenqi Zhang is a Chinese-Australian chemist and BBSRC David Phillips Research Fellow of the Department of Chemistry , University of Cambridge , where she is also a Fellow of Corpus Christi College (2019-present). She was awarded the 2020 RSC Felix Franks Biotechnology Medal for her research into re-wiring photosynthesis to provide sustainable fuel sources. [ 3 ]
Zhang was born in China , and moved to Gosford on the Central Coast (New South Wales) , Australia at age eight. [ 4 ] [ 5 ] She credits her mother's stories explaining the scientific basis of various phenomena with stimulating her interest in science. [ 6 ] She moved to Sydney to attend the University of Sydney , where she completed a Bachelor of Science (Advanced) in 2007 and a PhD in Chemistry under the supervision of Professor Trevor Hambley in 2011. [ 7 ] [ 8 ] During her PhD, Zhang also briefly worked at the Hebrew University of Jerusalem . [ 9 ]
Zhang's doctoral research was in the area of bioinorganic chemistry , [ 10 ] and she worked on the development of a platinum-based library of chemotherapeutic candidates featuring anthraquinone ligands and redox activity. This involved using a variety of imaging techniques (including those based on synchrotron radiation ) to study the biological distributions and metabolism of the chemotherapeutics in 3D solid tumour models, [ 11 ] [ 12 ] [ 13 ] and synthetic strategies to generate new examples of such complexes. [ 14 ]
Zhang sought a change in research field following her PhD, [ 15 ] and in 2013 she joined the group of Professor Erwin Reisner at the University of Cambridge as a postdoctoral fellow after receiving a Marie Skłodowska-Curie International Fellowship , [ 16 ] also becoming a Research Associate of St John's College . [ 17 ] This brought her into sustainability research, in particular artificial photosynthesis . [ 18 ] [ 19 ] Her postdoctoral research involved developing ways to wire oxidoreductases to electrodes and use photosynthesis to generate a sustainable biofuel, especially photosystem II . [ 20 ] [ 21 ] [ 22 ]
In 2018, Zhang was awarded a BBSRC David Phillips Fellowship to start her own, independent research group in the Department of Chemistry at Cambridge. [ 23 ] [ 24 ] In her independent career, she has continued to work on the re-wiring of photosynthesis but now focuses on doing so in live cells. [ 25 ] [ 26 ] She also became a Fellow of Corpus Christi College , where she is now Director of Studies in Natural Sciences Chemistry. [ 27 ] Zhang was recognised for her contributions to semi-artificial photosynthesis with the award of the Felix Franks Biotechnology Medal from the RSC in 2020. [ 28 ] | https://en.wikipedia.org/wiki/Jenny_Zhang_(chemist) |
In mathematics , Jensen's inequality , named after the Danish mathematician Johan Jensen , relates the value of a convex function of an integral to the integral of the convex function. It was proved by Jensen in 1906, [ 1 ] building on an earlier proof of the same inequality for doubly-differentiable functions by Otto Hölder in 1889. [ 2 ] Given its generality, the inequality appears in many forms depending on the context, some of which are presented below. In its simplest form the inequality states that the convex transformation of a mean is less than or equal to the mean applied after convex transformation (or equivalently, the opposite inequality for concave transformations). [ 3 ]
Jensen's inequality generalizes the statement that the secant line of a convex function lies above the graph of the function , which is Jensen's inequality for two points: the secant line consists of weighted means of the convex function (for t ∈ [0,1]),
while the graph of the function is the convex function of the weighted means,
Thus, Jensen's inequality in this case is
In the context of probability theory , it is generally stated in the following form: if X is a random variable and φ is a convex function, then
The difference between the two sides of the inequality, E [ φ ( X ) ] − φ ( E [ X ] ) {\displaystyle \operatorname {E} \left[\varphi (X)\right]-\varphi \left(\operatorname {E} [X]\right)} , is called the Jensen gap . [ 4 ]
The classical form of Jensen's inequality involves several numbers and weights. The inequality can be stated quite generally using either the language of measure theory or (equivalently) probability. In the probabilistic setting, the inequality can be further generalized to its full strength .
For a real convex function φ {\displaystyle \varphi } , numbers x 1 , x 2 , … , x n {\displaystyle x_{1},x_{2},\ldots ,x_{n}} in its domain, and positive weights a i {\displaystyle a_{i}} , Jensen's inequality can be stated as:
and the inequality is reversed if φ {\displaystyle \varphi } is concave , which is
Equality holds if and only if x 1 = x 2 = ⋯ = x n {\displaystyle x_{1}=x_{2}=\cdots =x_{n}} or φ {\displaystyle \varphi } is linear on a domain containing x 1 , x 2 , ⋯ , x n {\displaystyle x_{1},x_{2},\cdots ,x_{n}} .
As a particular case, if the weights a i {\displaystyle a_{i}} are all equal, then ( 1 ) and ( 2 ) become
For instance, the function log( x ) is concave , so substituting φ ( x ) = log ( x ) {\displaystyle \varphi (x)=\log(x)} in the previous formula ( 4 ) establishes the (logarithm of the) familiar arithmetic-mean/geometric-mean inequality :
log ( ∑ i = 1 n x i n ) ≥ ∑ i = 1 n log ( x i ) n {\displaystyle \log \!\left({\frac {\sum _{i=1}^{n}x_{i}}{n}}\right)\geq {\frac {\sum _{i=1}^{n}\log \!\left(x_{i}\right)}{n}}} exp ( log ( ∑ i = 1 n x i n ) ) ≥ exp ( ∑ i = 1 n log ( x i ) n ) {\displaystyle \exp \!\left(\log \!\left({\frac {\sum _{i=1}^{n}x_{i}}{n}}\right)\right)\geq \exp \!\left({\frac {\sum _{i=1}^{n}\log \!\left(x_{i}\right)}{n}}\right)} x 1 + x 2 + ⋯ + x n n ≥ x 1 ⋅ x 2 ⋯ x n n {\displaystyle {\frac {x_{1}+x_{2}+\cdots +x_{n}}{n}}\geq {\sqrt[{n}]{x_{1}\cdot x_{2}\cdots x_{n}}}}
A common application has x as a function of another variable (or set of variables) t , that is, x i = g ( t i ) {\displaystyle x_{i}=g(t_{i})} . All of this carries directly over to the general continuous case: the weights a i are replaced by a non-negative integrable function f ( x ) , such as a probability distribution, and the summations are replaced by integrals.
Let ( Ω , A , μ ) {\displaystyle (\Omega ,A,\mu )} be a probability space . Let f : Ω → R {\displaystyle f:\Omega \to \mathbb {R} } be a μ {\displaystyle \mu } -measurable function and φ : R → R {\displaystyle \varphi :\mathbb {R} \to \mathbb {R} } be convex. Then: [ 5 ] φ ( ∫ Ω f d μ ) ≤ ∫ Ω φ ∘ f d μ {\displaystyle \varphi \left(\int _{\Omega }f\,\mathrm {d} \mu \right)\leq \int _{\Omega }\varphi \circ f\,\mathrm {d} \mu }
In real analysis, we may require an estimate on
where a , b ∈ R {\displaystyle a,b\in \mathbb {R} } , and f : [ a , b ] → R {\displaystyle f\colon [a,b]\to \mathbb {R} } is a non-negative Lebesgue- integrable function. In this case, the Lebesgue measure of [ a , b ] {\displaystyle [a,b]} need not be unity. However, by integration by substitution, the interval can be rescaled so that it has measure unity. Then Jensen's inequality can be applied to get [ 6 ]
The same result can be equivalently stated in a probability theory setting, by a simple change of notation. Let ( Ω , F , P ) {\displaystyle (\Omega ,{\mathfrak {F}},\operatorname {P} )} be a probability space , X an integrable real-valued random variable and φ {\displaystyle \varphi } a convex function . Then [ 7 ] φ ( E [ X ] ) ≤ E [ φ ( X ) ] . {\displaystyle \varphi {\big (}\operatorname {E} [X]{\big )}\leq \operatorname {E} [\varphi (X)].}
In this probability setting, the measure μ is intended as a probability P {\displaystyle \operatorname {P} } , the integral with respect to μ as an expected value E {\displaystyle \operatorname {E} } , and the function f {\displaystyle f} as a random variable X .
Note that the equality holds if and only if φ {\displaystyle \varphi } is a linear function on some convex set A {\displaystyle A} such that P ( X ∈ A ) = 1 {\displaystyle P(X\in A)=1} (which follows by inspecting the measure-theoretical proof below).
More generally, let T be a real topological vector space , and X a T -valued integrable random variable. In this general setting, integrable means that there exists an element E [ X ] {\displaystyle \operatorname {E} [X]} in T , such that for any element z in the dual space of T : E | ⟨ z , X ⟩ | < ∞ {\displaystyle \operatorname {E} |\langle z,X\rangle |<\infty } , and ⟨ z , E [ X ] ⟩ = E [ ⟨ z , X ⟩ ] {\displaystyle \langle z,\operatorname {E} [X]\rangle =\operatorname {E} [\langle z,X\rangle ]} . Then, for any measurable convex function φ and any sub- σ-algebra G {\displaystyle {\mathfrak {G}}} of F {\displaystyle {\mathfrak {F}}} :
Here E [ ⋅ ∣ G ] {\displaystyle \operatorname {E} [\cdot \mid {\mathfrak {G}}]} stands for the expectation conditioned to the σ-algebra G {\displaystyle {\mathfrak {G}}} . This general statement reduces to the previous ones when the topological vector space T is the real axis , and G {\displaystyle {\mathfrak {G}}} is the trivial σ -algebra {∅, Ω} (where ∅ is the empty set , and Ω is the sample space ). [ 8 ]
Let X be a one-dimensional random variable with mean μ {\displaystyle \mu } and variance σ 2 ≥ 0 {\displaystyle \sigma ^{2}\geq 0} . Let φ ( x ) {\displaystyle \varphi (x)} be a twice differentiable function, and define the function
Then [ 9 ]
In particular, when φ ( x ) {\displaystyle \varphi (x)} is convex, then φ ″ ( x ) ≥ 0 {\displaystyle \varphi ''(x)\geq 0} , and the standard form of Jensen's inequality immediately follows for the case where φ ( x ) {\displaystyle \varphi (x)} is additionally assumed to be twice differentiable.
Jensen's inequality can be proved in several ways, and three different proofs corresponding to the different statements above will be offered. Before embarking on these mathematical derivations, however, it is worth analyzing an intuitive graphical argument based on the probabilistic case where X is a real number (see figure). Assuming a hypothetical distribution of X values, one can immediately identify the position of E [ X ] {\displaystyle \operatorname {E} [X]} and its image φ ( E [ X ] ) {\displaystyle \varphi (\operatorname {E} [X])} in the graph. Noticing that for convex mappings Y = φ ( x ) of some x values the corresponding distribution of Y values is increasingly "stretched up" for increasing values of X , it is easy to see that the distribution of Y is broader in the interval corresponding to X > X 0 and narrower in X < X 0 for any X 0 ; in particular, this is also true for X 0 = E [ X ] {\displaystyle X_{0}=\operatorname {E} [X]} . Consequently, in this picture the expectation of Y will always shift upwards with respect to the position of φ ( E [ X ] ) {\displaystyle \varphi (\operatorname {E} [X])} . A similar reasoning holds if the distribution of X covers a decreasing portion of the convex function, or both a decreasing and an increasing portion of it. This "proves" the inequality, i.e.
with equality when φ ( X ) is not strictly convex, e.g. when it is a straight line, or when X follows a degenerate distribution (i.e. is a constant).
The proofs below formalize this intuitive notion.
If λ 1 and λ 2 are two arbitrary nonnegative real numbers such that λ 1 + λ 2 = 1 then convexity of φ implies
This can be generalized: if λ 1 , ..., λ n are nonnegative real numbers such that λ 1 + ... + λ n = 1 , then
for any x 1 , ..., x n .
The finite form of the Jensen's inequality can be proved by induction : by convexity hypotheses, the statement is true for n = 2. Suppose the statement is true for some n , so
for any λ 1 , ..., λ n such that λ 1 + ... + λ n = 1 .
One needs to prove it for n + 1 . At least one of the λ i is strictly smaller than 1 {\displaystyle 1} , say λ n +1 ; therefore by convexity inequality:
Since λ 1 + ... + λ n + λ n +1 = 1 ,
applying the inductive hypothesis gives
therefore
We deduce the inequality is true for n + 1 , by induction it follows that the result is also true for all integer n greater than 2.
In order to obtain the general inequality from this finite form, one needs to use a density argument. The finite form can be rewritten as:
where μ n is a measure given by an arbitrary convex combination of Dirac deltas :
Since convex functions are continuous , and since convex combinations of Dirac deltas are weakly dense in the set of probability measures (as could be easily verified), the general statement is obtained simply by a limiting procedure.
Let g {\displaystyle g} be a real-valued μ {\displaystyle \mu } -integrable function on a probability space Ω {\displaystyle \Omega } , and let φ {\displaystyle \varphi } be a convex function on the real numbers. Since φ {\displaystyle \varphi } is convex, at each real number x {\displaystyle x} we have a nonempty set of subderivatives , which may be thought of as lines touching the graph of φ {\displaystyle \varphi } at x {\displaystyle x} , but which are below the graph of φ {\displaystyle \varphi } at all points (support lines of the graph).
Now, if we define
because of the existence of subderivatives for convex functions, we may choose a {\displaystyle a} and b {\displaystyle b} such that
for all real x {\displaystyle x} and
But then we have that
for almost all ω ∈ Ω {\displaystyle \omega \in \Omega } . Since we have a probability measure, the integral is monotone with μ ( Ω ) = 1 {\displaystyle \mu (\Omega )=1} so that
as desired.
Let X be an integrable random variable that takes values in a real topological vector space T . Since φ : T → R {\displaystyle \varphi :T\to \mathbb {R} } is convex, for any x , y ∈ T {\displaystyle x,y\in T} , the quantity
is decreasing as θ approaches 0 + . In particular, the subdifferential of φ {\displaystyle \varphi } evaluated at x in the direction y is well-defined by
It is easily seen that the subdifferential is linear in y [ citation needed ] (that is false and the assertion requires Hahn-Banach theorem to be proved) and, since the infimum taken in the right-hand side of the previous formula is smaller than the value of the same term for θ = 1 , one gets
In particular, for an arbitrary sub- σ -algebra G {\displaystyle {\mathfrak {G}}} we can evaluate the last inequality when x = E [ X ∣ G ] , y = X − E [ X ∣ G ] {\displaystyle x=\operatorname {E} [X\mid {\mathfrak {G}}],\,y=X-\operatorname {E} [X\mid {\mathfrak {G}}]} to obtain
Now, if we take the expectation conditioned to G {\displaystyle {\mathfrak {G}}} on both sides of the previous expression, we get the result since:
by the linearity of the subdifferential in the y variable, and the following well-known property of the conditional expectation :
Suppose Ω is a measurable subset of the real line and f ( x ) is a non-negative function such that
In probabilistic language, f is a probability density function .
Then Jensen's inequality becomes the following statement about convex integrals:
If g is any real-valued measurable function and φ {\textstyle \varphi } is convex over the range of g , then
If g ( x ) = x , then this form of the inequality reduces to a commonly used special case:
This is applied in Variational Bayesian methods .
If g ( x ) = x 2n , and X is a random variable, then g is convex as
and so
In particular, if some even moment 2n of X is finite, X has a finite mean. An extension of this argument shows X has finite moments of every order l ∈ N {\displaystyle l\in \mathbb {N} } dividing n .
Let Ω = { x 1 , ... x n }, and take μ to be the counting measure on Ω , then the general form reduces to a statement about sums:
provided that λ i ≥ 0 and
There is also an infinite discrete form.
Jensen's inequality is of particular importance in statistical physics when the convex function is an exponential, giving:
where the expected values are with respect to some probability distribution in the random variable X .
Proof: Let φ ( x ) = e x {\displaystyle \varphi (x)=e^{x}} in φ ( E [ X ] ) ≤ E [ φ ( X ) ] . {\displaystyle \varphi \left(\operatorname {E} [X]\right)\leq \operatorname {E} \left[\varphi (X)\right].}
If p ( x ) is the true probability density for X , and q ( x ) is another density, then applying Jensen's inequality for the random variable Y ( X ) = q ( X )/ p ( X ) and the convex function φ ( y ) = −log( y ) gives
Therefore:
a result called Gibbs' inequality .
It shows that the average message length is minimised when codes are assigned on the basis of the true probabilities p rather than any other distribution q . The quantity that is non-negative is called the Kullback–Leibler divergence of q from p , where D ( p ( x ) ‖ q ( x ) ) = ∫ p ( x ) log ( p ( x ) q ( x ) ) d x {\displaystyle D(p(x)\|q(x))=\int p(x)\log \left({\frac {p(x)}{q(x)}}\right)dx} .
Since −log( x ) is a strictly convex function for x > 0 , it follows that equality holds when p ( x ) equals q ( x ) almost everywhere.
If L is a convex function and G {\displaystyle {\mathfrak {G}}} a sub-sigma-algebra, then, from the conditional version of Jensen's inequality, we get
So if δ( X ) is some estimator of an unobserved parameter θ given a vector of observables X ; and if T ( X ) is a sufficient statistic for θ; then an improved estimator, in the sense of having a smaller expected loss L , can be obtained by calculating
the expected value of δ with respect to θ, taken over all possible vectors of observations X compatible with the same value of T ( X ) as that observed. Further, because T is a sufficient statistic, δ 1 ( X ) {\displaystyle \delta _{1}(X)} does not depend on θ, hence, becomes a statistic.
This result is known as the Rao–Blackwell theorem .
The relation between risk aversion and declining marginal utility for scalar outcomes can be stated formally with Jensen's inequality: risk aversion can be stated as preferring a certain outcome u ( E [ x ] ) {\displaystyle u(E[x])} to a fair gamble with potentially larger but uncertain outcome of u ( x ) {\displaystyle u(x)} :
u ( E [ x ] ) > E [ u ( x ) ] {\displaystyle u(E[x])>E[u(x)]} .
But this is simply Jensen's inequality for a concave u ( x ) {\displaystyle u(x)} : a utility function that exhibits declining marginal utility. [ 11 ]
Beyond its classical formulation for real numbers and convex functions, Jensen’s inequality has been extended to the realm of operator theory. In this non‐commutative setting the inequality is expressed in terms of operator convex functions—that is, functions defined on an interval I that satisfy
for every pair of self‐adjoint operators x and y (with spectra in I) and every scalar λ ∈ [ 0 , 1 ] {\displaystyle \lambda \in [0,1]} . Hansen and Pedersen [ 12 ] established a definitive version of this inequality by considering genuine non‐commutative convex combinations. In particular, if one has an n‑tuple of bounded self‐adjoint operators x 1 , … , x n {\displaystyle x_{1},\dots ,x_{n}} with spectra in I and an n‑tuple of operators a 1 , … , a n {\displaystyle a_{1},\dots ,a_{n}} satisfying
then the following operator Jensen inequality holds:
This result shows that the convex transformation “respects” non-commutative convex combinations, thereby extending the classical inequality to operators without the need for additional restrictions on the interval of definition. [ 12 ] A closely related extension is given by the Jensen trace inequality. For a continuous convex function f defined on I, if one considers self‐adjoint matrices x 1 , … , x n {\displaystyle x_{1},\dots ,x_{n}} (with spectra in I) and matrices a 1 , … , a n {\displaystyle a_{1},\dots ,a_{n}} satisfying ∑ i = 1 n a i ∗ a i = I {\displaystyle \sum _{i=1}^{n}a_{i}^{*}a_{i}=I} , then one has
This inequality naturally extends to C*-algebras equipped with a finite trace and is particularly useful in applications ranging from quantum statistical mechanics to information theory.
Furthermore, contractive versions of these operator inequalities are available when one only assumes ∑ i = 1 n a i t a i ≤ I {\displaystyle \sum _{i=1}^{n}a_{i}^{t}a_{i}\leq I} , provided that additional conditions such as f ( 0 ) ≤ 0 {\displaystyle f(0)\leq 0} (when 0 ∈ I) are imposed. Extensions to continuous fields of operators and to settings involving conditional expectations on C-algebras further illustrate the broad applicability of these generalizations. | https://en.wikipedia.org/wiki/Jensen's_inequality |
Jeremy Keith Burdett (July 1, 1947 – June 23, 1997), or Jeremy K. Burdett , was a British-American chemist known for his work on bridging the gap [ 1 ] between molecular science and solid state chemistry from an electron orbital viewpoint. [ 2 ]
Burdett was a native of London, UK. He studied at the Magdalene College , University of Cambridge , receiving his bachelor's degree in 1968 in natural sciences with a specialization in chemistry. He obtained a master's degree from the University of Michigan in 1970 and worked as a Power Foundation Fellow with Jerry Current . He returned to the University of Cambridge and received a Ph.D. in 1972 under the supervision of Jim J. Turner. Subsequently, Burdett moved to Newcastle University along with Jim J. Turner's group and was appointed senior research officer. In 1977, Burdett spent a sabbatical at Cornell University with Roald Hoffmann , who greatly influenced Burdett's research direction. In 1978, Burdett joined the faculty at the University of Chicago , where he spent the rest of his career. [ 3 ]
Burdett received the following accolades during his career, [ 3 ] [ 4 ]
Burdett's first wife was Wendy Greenwood, with whom he had two sons, Rufus and Harry. Burdett passed away at his summer home in Kalamazoo, Michigan after attending a conference in Ann Arbor, Michigan . [ 5 ] | https://en.wikipedia.org/wiki/Jeremy_Burdett |
Jeremy Henley Burroughes FREng FRS (born August 1960) is a British physicist and engineer , known for his contributions to the development of organic electronics through his work on the science of semiconducting polymers and molecules and their application. [ 6 ] He is the Chief Technology Officer of Cambridge Display Technology , a company specialising in the development of technologies based on polymer light-emitting diodes .
Burroughes earned his PhD from the University of Cambridge in 1989. [ 3 ] His thesis was entitled The physical processes in organic semiconducting polymer devices. [ 7 ]
Early in his career, Burroughes discovered that certain conjugated polymers were capable of emitting light when an electric current passed through them. The discovery of this previously unknown form of electroluminescence led to the foundation of Cambridge Display Technology where Burroughes has been responsible for a number of technology innovations, including the direct printing of full-colour OLED displays . [ 6 ]
Burroughes was elected a Fellow of the Royal Society (FRS) in 2012 . [ 6 ] His certificate of election reads:
Burroughes made the seminal advances in the science and engineering of semiconducting polymers that have brought these materials from research to the marketplace. His early papers from Cambridge on polymer FETs (1988) and LEDs (1990) defined the scope of the field. In his role as Chief Technology Officer at Cambridge Display Technology he has transformed early demonstration into fully manufacturable technology, using new device architectures, new materials and new manufacturing processes such as direct printing of full colour LED displays. This engineering programme has generated fundamental understanding of the underlying device physics. [ 8 ]
This article about a physicist of the United Kingdom is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Jeremy_Burroughes |
Jerk (also known as jolt [ 1 ] ) is the rate of change of an object's acceleration over time. It is a vector quantity (having both magnitude and direction). Jerk is most commonly denoted by the symbol j and expressed in m/s 3 ( SI units ) or standard gravities per second [ 2 ] ( g 0 /s).
As a vector, jerk j can be expressed as the first time derivative of acceleration , second time derivative of velocity , and third time derivative of position :
j ( t ) = d a ( t ) d t = d 2 v ( t ) d t 2 = d 3 r ( t ) d t 3 {\displaystyle \mathbf {j} (t)={\frac {\mathrm {d} \mathbf {a} (t)}{\mathrm {d} t}}={\frac {\mathrm {d} ^{2}\mathbf {v} (t)}{\mathrm {d} t^{2}}}={\frac {\mathrm {d} ^{3}\mathbf {r} (t)}{\mathrm {d} t^{3}}}}
Where:
Third-order differential equations of the form J ( x . . . , x ¨ , x ˙ , x ) = 0 {\displaystyle J\left({\overset {\mathbf {...} }{x}},{\ddot {x}},{\dot {x}},x\right)=0} are sometimes called jerk equations . When converted to an equivalent system of three ordinary first-order non-linear differential equations, jerk equations are the minimal setting for solutions showing chaotic behaviour . This condition generates mathematical interest in jerk systems . Systems involving fourth-order derivatives or higher are accordingly called hyperjerk systems . [ 3 ]
Human body position is controlled by balancing the forces of antagonistic muscles . In balancing a given force, such as holding up a weight, the postcentral gyrus establishes a control loop to achieve the desired equilibrium . If the force changes too quickly, the muscles cannot relax or tense fast enough and overshoot in either direction, causing a temporary loss of control. The reaction time for responding to changes in force depends on physiological limitations and the attention level of the brain: an expected change will be stabilized faster than a sudden decrease or increase of load.
To avoid vehicle passengers losing control over body motion and getting injured, it is necessary to limit the exposure to both the maximum force (acceleration) and maximum jerk, since time is needed to adjust muscle tension and adapt to even limited stress changes. Sudden changes in acceleration can cause injuries such as whiplash . [ 4 ] Excessive jerk may also result in an uncomfortable ride, even at levels that do not cause injury. Engineers expend considerable design effort minimizing "jerky motion" on elevators , trams , and other conveyances.
For example, consider the effects of acceleration and jerk when riding in a car:
For a constant mass m , acceleration a is directly proportional to force F according to Newton's second law of motion : F = m a {\displaystyle \mathbf {F} =m\mathbf {a} }
In classical mechanics of rigid bodies, there are no forces associated with the derivatives of acceleration; however, physical systems experience oscillations and deformations as a result of jerk. In designing the Hubble Space Telescope , NASA set limits on both jerk and jounce . [ 5 ]
The Abraham–Lorentz force is the recoil force on an accelerating charged particle emitting radiation. This force is proportional to the particle's jerk and to the square of its charge . The Wheeler–Feynman absorber theory is a more advanced theory, applicable in a relativistic and quantum environment, and accounting for self-energy .
Discontinuities in acceleration do not occur in real-world environments because of deformation , quantum mechanics effects, and other causes. However, a jump-discontinuity in acceleration and, accordingly, unbounded jerk are feasible in an idealized setting, such as an idealized point mass moving along a piecewise smooth , whole continuous path. The jump-discontinuity occurs at points where the path is not smooth. Extrapolating from these idealized settings, one can qualitatively describe, explain and predict the effects of jerk in real situations.
Jump-discontinuity in acceleration can be modeled using a Dirac delta function in jerk, scaled to the height of the jump. Integrating jerk over time across the Dirac delta yields the jump-discontinuity.
For example, consider a path along an arc of radius r , which tangentially connects to a straight line. The whole path is continuous, and its pieces are smooth. Now assume a point particle moves with constant speed along this path, so its tangential acceleration is zero. The centripetal acceleration given by v 2 / r is normal to the arc and inward. When the particle passes the connection of pieces, it experiences a jump-discontinuity in acceleration given by v 2 / r , and it undergoes a jerk that can be modeled by a Dirac delta, scaled to the jump-discontinuity.
For a more tangible example of discontinuous acceleration, consider an ideal spring–mass system with the mass oscillating on an idealized surface with friction. The force on the mass is equal to the vector sum of the spring force and the kinetic frictional force . When the velocity changes sign (at the maximum and minimum displacements ), the magnitude of the force on the mass changes by twice the magnitude of the frictional force, because the spring force is continuous and the frictional force reverses direction with velocity. The jump in acceleration equals the force on the mass divided by the mass. That is, each time the mass passes through a minimum or maximum displacement, the mass experiences a discontinuous acceleration, and the jerk contains a Dirac delta until the mass stops. The static friction force adapts to the residual spring force, establishing equilibrium with zero net force and zero velocity.
Consider the example of a braking and decelerating car. The brake pads generate kinetic frictional forces and constant braking torques on the disks (or drums ) of the wheels. Rotational velocity decreases linearly to zero with constant angular deceleration. The frictional force, torque, and car deceleration suddenly reach zero, which indicates a Dirac delta in physical jerk. The Dirac delta is smoothed down by the real environment, the cumulative effects of which are analogous to damping of the physiologically perceived jerk. This example neglects the effects of tire sliding, suspension dipping, real deflection of all ideally rigid mechanisms, etc.
Another example of significant jerk, analogous to the first example, is the cutting of a rope with a particle on its end. Assume the particle is oscillating in a circular path with non-zero centripetal acceleration. When the rope is cut, the particle's path changes abruptly to a straight path, and the force in the inward direction changes suddenly to zero. Imagine a monomolecular fiber cut by a laser; the particle would experience very high rates of jerk because of the extremely short cutting time.
Consider a rigid body rotating about a fixed axis in an inertial reference frame . If its angular position as a function of time is θ ( t ) , the angular velocity, acceleration, and jerk can be expressed as follows:
Angular acceleration equals the torque acting on the body, divided by the body's moment of inertia with respect to the momentary axis of rotation. A change in torque results in angular jerk.
The general case of a rotating rigid body can be modeled using kinematic screw theory , which includes one axial vector , angular velocity Ω ( t ) , and one polar vector , linear velocity v ( t ) . From this, the angular acceleration is defined as
α ( t ) = d d t ω ( t ) = ω ˙ ( t ) {\displaystyle {\boldsymbol {\alpha }}(t)={\frac {\mathrm {d} }{\mathrm {d} t}}{\boldsymbol {\omega }}(t)={\dot {\boldsymbol {\omega }}}(t)}
and the angular jerk is given by ζ ( t ) = d d t α ( t ) = α ˙ ( t ) = ω ¨ ( t ) {\displaystyle {\boldsymbol {\zeta }}(t)={\frac {\mathrm {d} }{\mathrm {d} t}}{\boldsymbol {\alpha }}(t)={\dot {\boldsymbol {\alpha }}}(t)={\ddot {\boldsymbol {\omega }}}(t)}
taking the angular acceleration from Angular acceleration#Particle in three dimensions as α = d ω d t = r × a r 2 − 2 r d r d t ω {\displaystyle {\boldsymbol {\alpha }}={\frac {d{\boldsymbol {\omega }}}{dt}}={\frac {\mathbf {r} \times \mathbf {a} }{r^{2}}}-{\frac {2}{r}}{\frac {dr}{dt}}{\boldsymbol {\omega }}} , we obtain
ζ = d α d t = 1 r 2 ( r × d a d t + d r d t × a ) − 2 r 3 d r d t ( r × a ) + 2 r 2 ( d r d t ) 2 ω − 2 r d 2 r d t 2 ω − 2 r d r d t d ω d t {\displaystyle {\begin{aligned}{\boldsymbol {\zeta }}={\frac {d{\boldsymbol {\alpha }}}{dt}}={\frac {1}{r^{2}}}\left(\mathbf {r} \times {\frac {d\mathbf {a} }{dt}}+{\frac {d\mathbf {r} }{dt}}\times \mathbf {a} \right)-{\frac {2}{r^{3}}}{\frac {dr}{dt}}\left(\mathbf {r} \times \mathbf {a} \right)\\\\+{\frac {2}{r^{2}}}\left({\frac {dr}{dt}}\right)^{2}{\boldsymbol {\omega }}-{\frac {2}{r}}{\frac {d^{2}r}{dt^{2}}}{\boldsymbol {\omega }}-{\frac {2}{r}}{\frac {dr}{dt}}{\frac {d{\boldsymbol {\omega }}}{dt}}\end{aligned}}}
replacing d ω d t {\displaystyle {\frac {d{\boldsymbol {\omega }}}{dt}}} we can have the last item as − 2 r d r d t d ω d t = − 2 r d r d t ( r × a r 2 − 2 r d r d t ω ) = − 2 r 3 d r d t ( r × a ) + 4 r 2 ( d r d t ) 2 ω {\displaystyle {\begin{aligned}-{\frac {2}{r}}{\frac {dr}{dt}}{\frac {d{\boldsymbol {\omega }}}{dt}}&=-{\frac {2}{r}}{\frac {dr}{dt}}\left({\frac {\mathbf {r} \times \mathbf {a} }{r^{2}}}-{\frac {2}{r}}{\frac {dr}{dt}}{\boldsymbol {\omega }}\right)\\\\&=-{\frac {2}{r^{3}}}{\frac {dr}{dt}}\left(\mathbf {r} \times \mathbf {a} \right)+{\frac {4}{r^{2}}}\left({\frac {dr}{dt}}\right)^{2}{\boldsymbol {\omega }}\end{aligned}}} , and we finally get
ζ = r × j r 2 + v × a r 2 − 4 r 3 d r d t ( r × a ) + 6 r 2 ( d r d t ) 2 ω − 2 r d 2 r d t 2 ω {\displaystyle {\begin{aligned}{\boldsymbol {\zeta }}={\frac {\mathbf {r} \times \mathbf {j} }{r^{2}}}+{\frac {\mathbf {v} \times \mathbf {a} }{r^{2}}}-{\frac {4}{r^{3}}}{\frac {dr}{dt}}\left(\mathbf {r} \times \mathbf {a} \right)+{\frac {6}{r^{2}}}\left({\frac {dr}{dt}}\right)^{2}{\boldsymbol {\omega }}-{\frac {2}{r}}{\frac {d^{2}r}{dt^{2}}}{\boldsymbol {\omega }}\end{aligned}}}
or vice versa, replacing ( r × a ) {\displaystyle \left(\mathbf {r} \times \mathbf {a} \right)} with α {\displaystyle {\boldsymbol {\alpha }}} : ζ = r × j r 2 + v × a r 2 − 4 r d r d t α − 2 r 2 ( d r d t ) 2 ω − 2 r d 2 r d t 2 ω {\displaystyle {\begin{aligned}{\boldsymbol {\zeta }}={\frac {\mathbf {r} \times \mathbf {j} }{r^{2}}}+{\frac {\mathbf {v} \times \mathbf {a} }{r^{2}}}-{\frac {4}{r}}{\frac {dr}{dt}}{\boldsymbol {\alpha }}-{\frac {2}{r^{2}}}\left({\frac {dr}{dt}}\right)^{2}{\boldsymbol {\omega }}-{\frac {2}{r}}{\frac {d^{2}r}{dt^{2}}}{\boldsymbol {\omega }}\end{aligned}}}
For example, consider a Geneva drive , a device used for creating intermittent rotation of a driven wheel (the blue wheel in the animation) by continuous rotation of a driving wheel (the red wheel in the animation). During one cycle of the driving wheel, the driven wheel's angular position θ changes by 90 degrees and then remains constant. Because of the finite thickness of the driving wheel's fork (the slot for the driving pin), this device generates a discontinuity in the angular acceleration α , and an unbounded angular jerk ζ in the driven wheel.
Jerk does not preclude the Geneva drive from being used in applications such as movie projectors and cams . In movie projectors, the film advances frame-by-frame, but the projector operation has low noise and is highly reliable because of the low film load (only a small section of film weighing a few grams is driven), the moderate speed (2.4 m/s), and the low friction.
With cam drive systems, use of a dual cam can avoid the jerk of a single cam; however, the dual cam is bulkier and more expensive. The dual-cam system has two cams on one axle that shifts a second axle by a fraction of a revolution. The graphic shows step drives of one-sixth and one-third rotation per one revolution of the driving axle. There is no radial clearance because two arms of the stepped wheel are always in contact with the double cam. Generally, combined contacts may be used to avoid the jerk (and wear and noise) associated with a single follower (such as a single follower gliding along a slot and changing its contact point from one side of the slot to the other can be avoided by using two followers sliding along the same slot, one side each).
An elastically deformable mass deforms under an applied force (or acceleration); the deformation is a function of its stiffness and the magnitude of the force. If the change in force is slow, the jerk is small, and the propagation of deformation is considered instantaneous as compared to the change in acceleration. The distorted body acts as if it were in a quasistatic regime , and only a changing force (nonzero jerk) can cause propagation of mechanical waves (or electromagnetic waves for a charged particle); therefore, for nonzero to high jerk, a shock wave and its propagation through the body should be considered.
The propagation of deformation is shown in the graphic "Compression wave patterns" as a compressional plane wave through an elastically deformable material. Also shown, for angular jerk, are the deformation waves propagating in a circular pattern, which causes shear stress and possibly other modes of vibration . The reflection of waves along the boundaries cause constructive interference patterns (not pictured), producing stresses that may exceed the material's limits. The deformation waves may cause vibrations, which can lead to noise, wear, and failure, especially in cases of resonance.
The graphic captioned "Pole with massive top" shows a block connected to an elastic pole and a massive top. The pole bends when the block accelerates, and when the acceleration stops, the top will oscillate ( damped ) under the regime of pole stiffness. One could argue that a greater (periodic) jerk might excite a larger amplitude of oscillation because small oscillations are damped before reinforcement by a shock wave. One can also argue that a larger jerk might increase the probability of exciting a resonant mode because the larger wave components of the shock wave have higher frequencies and Fourier coefficients .
To reduce the amplitude of excited stress waves and vibrations, one can limit jerk by shaping motion and making the acceleration continuous with slopes as flat as possible. Due to limitations of abstract models, algorithms for reducing vibrations include higher derivatives, such as jounce , or suggest continuous regimes for both acceleration and jerk. One concept for limiting jerk is to shape acceleration and deceleration sinusoidally with zero acceleration in between (see graphic captioned "Sinusoidal acceleration profile"), making the speed appear sinusoidal with constant maximum speed. The jerk, however, will remain discontinuous at the points where acceleration enters and leaves the zero phases.
Roads and tracks are designed to limit the jerk caused by changes in their curvature. Design standards for high-speed rail vary from 0.2 m/s 3 to 0.6 m/s 3 . [ 6 ] Track transition curves limit the jerk when transitioning from a straight line to a curve, or vice versa. Recall that in constant-speed motion along an arc, acceleration is zero in the tangential direction and nonzero in the inward normal direction. Transition curves gradually increase the curvature and, consequently, the centripetal acceleration.
An Euler spiral , the theoretically optimum transition curve, linearly increases centripetal acceleration and results in constant jerk (see graphic). In real-world applications, the plane of the track is inclined ( cant ) along the curved sections. The incline causes vertical acceleration, which is a design consideration for wear on the track and embankment. The Wiener Kurve (Viennese Curve) is a patented curve designed to minimize this wear. [ 7 ] [ 8 ]
Rollercoasters [ 4 ] are also designed with track transitions to limit jerk. When entering a loop, acceleration values can reach around 4 g (40 m/s 2 ), and riding in this high acceleration environment is only possible with track transitions. S-shaped curves, such as figure eights, also use track transitions for smooth rides.
In motion control , the design focus is on straight, linear motion, with the need to move a system from one steady position to another (point-to-point motion). The design concern from a jerk perspective is vertical jerk; the jerk from tangential acceleration is effectively zero since linear motion is non-rotational.
Motion control applications include passenger elevators and machining tools. Limiting vertical jerk is considered essential for elevator riding convenience. [ 9 ] ISO 8100-34 [ 10 ] specifies measurement methods for elevator ride quality with respect to jerk, acceleration, vibration, and noise; however, the standard does not specify levels for acceptable or unacceptable ride quality. It is reported [ 11 ] that most passengers rate a vertical jerk of 2 m/s 3 as acceptable and 6 m/s 3 as intolerable. For hospitals, 0.7 m/s 3 is the recommended limit.
A primary design goal for motion control is to minimize the transition time without exceeding speed, acceleration, or jerk limits. Consider a third-order motion-control profile with quadratic ramping and deramping phases in velocity (see figure).
This motion profile consists of the following seven segments:
Segment four's time period (constant velocity) varies with distance between the two positions. If this distance is so small that omitting segment four would not suffice, then segments two and six (constant acceleration) could be equally reduced, and the constant velocity limit would not be reached. If this modification does not sufficiently reduce the crossed distance, then segments one, three, five, and seven could be shortened by an equal amount, and the constant acceleration limits would not be reached.
Other motion profile strategies are used, such as minimizing the square of jerk for a given transition time [ 12 ] and, as discussed above, sinusoidal-shaped acceleration profiles. Motion profiles are tailored for specific applications including machines, people movers, chain hoists, automobiles, and robotics.
Jerk is an important consideration in manufacturing processes. Rapid changes in acceleration of a cutting tool can lead to premature tool wear and result in uneven cuts; consequently, modern motion controllers include jerk limitation features. In mechanical engineering, jerk, in addition to velocity and acceleration, is considered in the development of cam profiles because of tribological implications and the ability of the actuated body to follow the cam profile without chatter . [ 13 ] Jerk is often considered when vibration is a concern. A device that measures jerk is called a "jerkmeter".
Further time derivatives have also been named, as snap or jounce (fourth derivative), crackle (fifth derivative), and pop (sixth derivative). [ 14 ] [ 15 ] The seventh derivative is known as "Lock", as it is a logical continuation to the cycle. The eighth derivative has been referred to as "Drop". [ citation needed ] Even though, the seventh and eighth derivative are not officially recognized and thus no reliable source is found. Time derivatives of position of higher order than four appear rarely. [ 16 ]
The terms snap , crackle , and pop —for the fourth, fifth, and sixth derivatives of position—were inspired by the advertising mascots Snap, Crackle, and Pop . [ 15 ] | https://en.wikipedia.org/wiki/Jerk_(physics) |
Jerry March , Ph.D. (August 1, 1929 – December 25, 1997) was an American organic chemist and a professor of chemistry at Adelphi University .
March authored the March's Advanced Organic Chemistry text, which is considered to be a pillar of graduate-level organic chemistry texts. The book was prepared in its fifth edition at the time of his death.
This biographical article about a chemist is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Jerry_March |
Jervine is a steroidal alkaloid with molecular formula C 27 H 39 NO 3 which is derived from the plant genus Veratrum . Similar to cyclopamine , which also occurs in the genus Veratrum , it is a teratogen implicated in birth defects when consumed by animals during a certain period of their gestation . [ citation needed ]
Jervine is a potent teratogen causing birth defects in vertebrates . In severe cases it can cause cyclopia and holoprosencephaly . [ citation needed ]
Jervine's biological activity is mediated via its interaction with the 7 pass trans membrane protein smoothened . Jervine binds with and inhibits smoothened , which is an integral part of the hedgehog signaling pathways . [ 1 ] With smoothened inhibited, the GLI1 transcription cannot be activated and hedgehog target genes cannot be transcribed. [ citation needed ] | https://en.wikipedia.org/wiki/Jervine |
Jesper deClaville Christiansen (born 30 June 1963 in Skive, Denmark) is a Danish professor in Materials Science and Technology. Professor Christiansen is known for his work in the field of mechanics of polymers, diffusion, rheology and micro and nano composites especially. [ 1 ]
Professor Jesper deClaville Christiansen was knighted on 11. April 2014 (ridder af Dannebrog ) by Queen Margrethe II of Denmark . [ 2 ]
Professor Christiansen received his PhD degree in 1989 after joint studies at Aalborg University , Denmark and Brunel University in London, U.K. His appointment to Professor in Materials Science came in 1998 where a 5-year research professorship in rheology of silicates initiated a chair in Materials Science.
Since 1 October 2012 Professor Christiansen has been coordinator of the European Community Research Program FP-7 Large EVOLUTION under the "Green Car" where a new electrical car 40% lighter than existing cars using green materials and technology is the aim. (12 mill. Euro). He was also coordinator for the successful European Community Research Program FP-7 Large Nanotough (2008–2011), where light and tough and strong nano composites were developed for space and automotive applications.
Professor Christiansen is active as reviewer for several journals: Langmuir, Journal of Polymer Science: Polymer Physics. Macromol. Mater. Eng., Oil & Gas Science and Technology-Revue de l'IFP, Composites A, Materials Science and Engineering, Geochimica Cosmochimica Acta, Journal of Engineering Education, Journal of Non-Newtonian Fluid Mechanics, American Mineralogist, Polymers and Polymer Composites, Journal of Rheology, Polymer Engineering and Science to mention some.
Professor Christiansen is Head of the Doctoral program in Mechanical and Manufacturing Engineering at Aalborg University
Professor Christiansen is author/co-author of more than 200 publications [ 3 ] | https://en.wikipedia.org/wiki/Jesper_deClaville_Christiansen |
Jesse Gelsinger (June 18, 1981 – September 17, 1999) was the first person publicly identified as having died in a clinical trial for gene therapy . Gelsinger suffered from ornithine transcarbamylase deficiency , an X-linked genetic disease of the liver , the symptoms of which include an inability to metabolize ammonia – a byproduct of protein breakdown. The disease is usually fatal at birth, but Gelsinger had a milder form of the disease, in which the ornithine transcarbamylase gene is mutated in only part of the patient's cells, a condition known as somatic mosaicism . As his deficiency was partial, Gelsinger managed to survive on a restricted diet and special medications.
Gelsinger joined a clinical trial run by the University of Pennsylvania that aimed at developing a treatment for infants born with the severe form of the disease. On September 13, 1999, Gelsinger was injected with an adenoviral vector carrying a corrected gene to test the safety of the procedure. He died four days later at the age of 18, on September 17, apparently having suffered a massive immune response triggered by the use of the viral vector to transport the gene into his cells, leading to multiple organ failure and brain death. [ 1 ]
A Food and Drug Administration (FDA) investigation concluded that the scientists involved in the trial, including the co-investigator James Wilson (Director of the Institute for Human Gene Therapy), broke several rules of conduct:
The University of Pennsylvania later issued a rebuttal, [ 2 ] but the university and Children's National Medical Center each agreed to pay more than $500,000 to the government. [ 3 ] Both Wilson and the University are reported to have had financial stakes in the research. [ 4 ] [ 5 ] After his death, all gene therapy trials in the United States halted for a time. [ 6 ] The Gelsinger case was a severe setback for scientists working in the field and a reminder of the risks involved. [ 7 ] | https://en.wikipedia.org/wiki/Jesse_Gelsinger |
Jesse Eugene Russell (born April 26, 1948) is an American inventor. He was trained as an electrical engineer at Tennessee State University and Stanford University , and worked in the field of wireless communication for over 20 years. He holds patents and continues to invent and innovate in the emerging area of next generation broadband wireless networks, technologies and services, often referred to as 4G. Russell was inducted into the US National Academy of Engineering for his contributions to the field of wireless communication. He pioneered the field of digital cellular communication in the 1980s through the use of high power linear amplification and low bit rate voice encoding technologies and received a patent in 1992 for his work in the area of digital cellular base station design.
Russell is Chairman and CEO of incNETWORKS, Inc., a New Jersey–based Broadband Wireless Communications Company focused on 4th Generation ( 4G ) Broadband Wireless Communications Technologies, Networks and Services.
Jesse Eugene Russell was born April 26, 1948, in Nashville, Tennessee , in the United States of America into a large African-American family with eight brothers and two sisters. He is the son of Charles Albert Russell and Mary Louise Russell. His early childhood was spent in economically and socially deprived neighborhoods within the inner-city of Nashville. During his early years, he focused on athletics and not academics. Russell graduated from Cameron High School in 1967. [ 1 ] A key turning point in Russell's life was the opportunity to attend a summer educational program at Fisk University [ 2 ] in Nashville, Tennessee. Russell participated in this educational opportunity and began his academic and intellectual pursuits. Russell continued his education at Tennessee State University [ 3 ] where he focused on electrical engineering. A Bachelor of Science Degree (BSEE) in Electrical Engineering was conferred in 1972 from Tennessee State University. As a top honor student in the School of Engineering, Russell became the first African American to be hired by AT&T Bell Laboratories directly from a Historically Black College or University (HBCUs) [ 4 ] and subsequently became the first African-American in the United States to be selected as the Eta Kappa Nu Outstanding Young Electrical Engineer of the Year in 1980. [ 5 ] Russell continued his academic pursuits and earned a Master of Electrical Engineering (MSEE) degree from Stanford University in 1973. [ 6 ]
Russell's innovations in wireless communication systems, architectures and technology related to radio access networks, end-user devices and in-building wireless communication systems have fundamentally changed the wireless communication industry. Russell is known for his invention of the digital cellular base station and the fibre optic microcell utilizing high power linear amplifier technology and digital modulation techniques, which enabled new digital services for cellular mobile users.
Russell has over 100 patents granted or in process, such as these in the table.
In 1990, Russell, with fellow AT&T Bell Labs engineers Farhad Barzegar and Can A. Eryaman, filed a patent for a digital mobile phone that supports the transmission of digital data. Their patent was cited several years later by Nokia and Motorola when they were developing 2G digital mobile phones. [ 14 ]
Russell joined Bell Labs as a Member of the Technical Staff. He was one of the first designers to use a microprocessor in the design of equipment for use in the telecommunication network for monitoring and tracking calling patterns within the Bell System Network. The system was referred to as the traffic data collection systems, which using microprocessor-based portable data terminals for interfacing to electromechanical switching systems.
Russell served in the following positions; Director of the AT&T Cellular Telecommunication Laboratory (Bell Labs), Vice President of Advanced Wireless Technology Laboratory (Bell Labs), Chief Technical Officer for the Network Wireless Systems Business Unit (Bell Labs), Chief Wireless Architect of AT&T, and Vice President of Advanced Communications Technologies for AT&T Laboratories (formerly a part of Bell Labs).
When he was the Director of the AT&T Cellular Telecommunication Laboratory, this Bell Labs Group was credited with the invention of cellular radio technology and received the United States' Medal of Technology for the invention.
Russell continued to develop his expertise as he established and led an Innovation Center focused on Applied Research in Advanced Communication Technologies that enabling AT&T to extend its existing portfolio of services and expand into new businesses and markets. As a key decision-maker in the selection and development of emerging communications technologies, Russell's efforts lead to the rapid realization of new access network platforms that enable AT&T to expand its broadband communication network options (i.e., Specialization: Cable Access Networks, DSL Access Networks, Power-line Carrier Access Networks, Fixed Wireless Access Networks, Satellite Access Networks and Broadband Wireless Communications Networks). The applications of these access technologies were one of the keys in expanding AT&T's interest in re-building it local access services business. | https://en.wikipedia.org/wiki/Jesse_Russell |
Jesse Sullivan (born c. 1966) is an American electrician best known for operating a fully robotic limb through a nerve-muscle graft, making him one of the first non-fictional cyborgs .
His bionic arm, a prototype developed by the Rehabilitation Institute of Chicago , differs from most other prostheses, in that it does not use pull cables or nub switches to function and instead uses micro-computers to perform a much wider range of complex motions. It is also the first prototype which enables him to sense pressure.
As an electrician, Jesse Sullivan accidentally touched an active cable that contained 7,000-7,500 volts of electricity . In May 2001, he had to have both his arms amputated at the shoulder.
Seven weeks after the amputation, Jesse Sullivan received matching bionic prostheses from Dr. Todd Kuiken of the Rehabilitation Institute of Chicago. Originally, they were operated from neural signals at the amputation sites, but Jesse Sullivan developed hyper-sensitivity from his skin grafts , causing great discomfort in those areas. Jesse Sullivan underwent neural surgery to graft nerves, which originally led to his arm, to his chest. The sensors for his bionic arms have been moved to the left side of his chest to receive signals from the newly grafted nerve endings .
While the prototype is being strengthened, Jesse Sullivan does day-to-day tasks using an older model.
This biographical article related to medicine in the United States is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Jesse_Sullivan |
In mathematics, the Jessen–Wintner theorem , introduced by Jessen and Wintner ( 1935 ), asserts that a random variable of Jessen–Wintner type , meaning the sum of an almost surely convergent series of independent discrete random variables, is of pure type.
This probability -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Jessen–Wintner_theorem |
A jet is a stream of fluid that is projected into a surrounding medium, usually from some kind of a nozzle , aperture or orifice . [ 1 ] Jets can travel long distances [ quantify ] without dissipating .
Jet fluid has higher speed compared to the surrounding fluid medium. In the case that the surrounding medium is assumed to be made up of the same fluid as the jet, and this fluid has viscosity , some of the surrounding fluid is carried along with the jet in a process called entrainment . [ 2 ]
Some animals, notably cephalopods , move by jet propulsion , as do rocket engines and jet engines .
Liquid jets are used in many different areas. In everyday life, you can find them for instance coming from the water tap , the showerhead , and from spray cans . In agriculture, they play a role in irrigation and in the application of crop protection products . In the field of medicine, you can find liquid jets for example in injection procedures or inhalers . Industry uses liquid jets for waterjet cutting , for coating materials or in cooling towers . Atomized liquid jets are essential for the efficiency of internal combustion engines . But they also play a crucial role in research, for example in the study of proteins , [ 3 ] phase transitions , [ 4 ] extreme states of matter , [ 5 ] laser plasmas , [ 6 ] High harmonic generation , [ 7 ] and also in particle physics experiments. [ 8 ] Also some animals, notably cephalopods , move by jet propulsion . Gas jets are found in rocket engines and jet engines .
Microscopic liquid jets have been studied for their potential application in noninvasive transdermal drug delivery . [ 9 ]
This fluid dynamics –related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Jet_(fluid) |
Jet Propulsion Laboratory Development Ephemeris (abbreviated JPL DE (number), or simply DE (number)) designates one of a series of mathematical models of the Solar System produced at the Jet Propulsion Laboratory in Pasadena, California , for use in spacecraft navigation and astronomy. The models consist of numeric representations of positions , velocities and accelerations of major Solar System bodies, tabulated at equally spaced intervals of time, covering a specified span of years. [ 1 ] Barycentric rectangular coordinates of the Sun , eight major planets and Pluto , and geocentric coordinates of the Moon are tabulated.
There have been many versions of the JPL DE , from the 1960s through the present, [ 2 ] in support of both robotic and crewed [ 3 ] spacecraft missions. Available documentation is limited, but we know DE69 was announced in 1969 to be the third release of the JPL Ephemeris Tapes, and was a special purpose, short-duration ephemeris. The then-current JPL Export Ephemeris was DE19 . These early releases were distributed on magnetic tape .
In the days before personal computers, computers were large and expensive, and numerical integrations such as these were run by large organizations with ample resources. The JPL ephemerides prior to DE405 were integrated on a Univac mainframe in double precision . For instance, DE102 , which was created in 1977, took six million steps and ran for nine days on a Univac 1100/81 . [ 4 ] DE405 was integrated on a DEC Alpha in quadruple precision . [ 5 ]
In the 1970s and early 1980s, much work was done in the astronomical community to update the astronomical almanacs from the theoretical work of the 1890s to modern, relativistic theory. From 1975 through 1982, six ephemerides were produced at JPL using the modern techniques of least-squares adjustment of numerically-integrated output to high precision data: DE96 in Nov. 1975, DE102 in Sep. 1977, DE111 in May 1980, DE118 in Sep. 1981, and DE200 in 1982. [ 6 ] DE102 was the first numerically integrated so-called Long Ephemeris, covering much of history for which useful astronomical observations were available: 1141 BC to AD 3001. DE200 , a version of DE118 migrated to the J2000.0 reference frame , was adopted as the fundamental ephemeris for the new almanacs starting in 1984. DE402 introduced coordinates referred to the International Celestial Reference Frame (ICRF). DE440 and DE441 were published in 2021, with improvements in the orbits of Jupiter, Saturn and Pluto from more recent spacecraft observations. [ 7 ]
JPL ephemerides have been the basis of the ephemerides of sun, moon and planets in the Astronomical Almanac since the volumes for 1984 through 2002, which used JPL's ephemeris DE200 . (From 2003 through 2014 the basis was updated to use DE405 , and further updated from 2015 when DE430 began to be used.) [ 8 ] [ 9 ]
Each ephemeris was produced by numerical integration of the equations of motion , starting from a set of initial conditions. Due to the precision of modern observational data, the analytical method of general perturbations could no longer be applied to a high enough accuracy to adequately reproduce the observations. The method of special perturbations was applied, using numerical integration to solve the n -body problem , in effect putting the entire Solar System into motion in the computer's memory, accounting for all relevant physical laws. The initial conditions were both constants such as planetary masses , from outside sources, and parameters such as initial positions and velocities, adjusted to produce output which was a "best fit" to a large set of observations . A least-squares technique was used to perform the fitting. [ 4 ] As of DE421, perturbations from 343 asteroids, representing about 90% of the mass of the main asteroid belt , have been included in the dynamical model. [ 10 ]
The physics modeled included the mutual Newtonian gravitational accelerations and their relativistic corrections (a modified form of the Einstein-Infeld-Hoffmann equations ), the accelerations caused by the tidal distortion of the Earth, the accelerations caused by the figure of the Earth and Moon, and a model of the lunar librations . [ 4 ]
The observational data in the fits has been an evolving set, including: ranges (distances) to planets measured by radio signals from spacecraft, [ 11 ] direct radar-ranging of planets, two-dimensional position fixes (on the plane of the sky) by VLBI of spacecraft, transit and CCD telescopic observations of planets and small bodies, and laser-ranging of retroreflectors on the Moon, among others. DE102 , for instance, was fit to 48,479 observations.
The time argument of the JPL integrated ephemerides, in early versions known as T eph , [ 12 ] became recognized as a relativistic coordinate time scale, as is necessary in precise work to account for the small relativistic effects of time dilation and simultaneity . The IAU 's 2006 redefinition of TDB became essentially equivalent to T eph , and the redefined TDB has been explicitly adopted in recent versions of the JPL ephemerides.
Positions and velocities of the Sun, Earth, Moon, and planets, along with the orientation of the Moon, are stored as Chebyshev polynomial coefficients fit in 32 day-long segments. [ 10 ] The ephemerides are now available via World Wide Web and FTP [ 13 ] as data files containing the Chebyshev coefficients, along with source code to recover (calculate) positions and velocities. [ 14 ] Files vary in the time periods they cover, ranging from a few hundred years to several thousand, and bodies they include. Data may be based on each planet's geometric center or a planetary-system barycenter .
The use of Chebyshev polynomials enables highly precise, efficient calculations for any given point in time. DE405 calculation for the inner planets "recovers" accuracy of about 0.001 seconds of arc (arcseconds) (equivalent to about 1 km at the distance of Mars ); for the outer planets it is generally about 0.1 arcseconds . The 'reduced accuracy' DE406 ephemeris gives an interpolating precision (relative to the full ephemeris values) no worse than 25 metres for any planet and no worse than 1 metre for the Moon.
Note that these precision numbers are for the interpolated values relative to the original tabulated coordinates. The overall precision and accuracy of interpolated values for describing the actual motions of the planets will be a function of both the precision of the ephemeris tabulated coordinates and the precision of the interpolation.
Ephemerides for Solar System bodies are available through a JPL website [ 17 ] and via FTP. [ 18 ]
Source: [ 10 ]
DE440 [ 19 ] was created in June 2020. The new DE440 / 441 general-purpose planetary solution includes seven additional years of ground and space-based astrometric data, data calibrations, and dynamical model improvements, most significantly involving Jupiter, Saturn, Pluto, and the Kuiper Belt. Inclusion of 30 new Kuiper-belt masses, and the Kuiper Belt ring mass, results in a time-varying shift of ~100 km in DE440's barycenter relative to DE430. The 114 Megabyte ephemeris files include the orientation of the Moon. It spans the years 1550–2650. JPL started transitioning to DE440 in early April 2021. Supplemental versions are also available which include the planetary geometric center of Mars as well as Mars' barycenter. [ 20 ]
DE441 [ 19 ] was created in June 2020. This ephemeris is longer than DE440, -13,200 to 17,191, but less accurate (due to neglecting lunar core-mantle damping). It is useful for analyzing historical observations that are outside the span of DE440.
DE102 was created in 1981; includes nutations but not librations. Referred to the dynamical equator and equinox of 1950. Covers early 1410 BC through late 3002 AD. [ 14 ]
DE200 was created in 1981; includes nutations but not librations. Referred to the dynamical equator and equinox of 2000. Covers late 1599 AD through early 2169 AD. This ephemeris was used for the Astronomical Almanac from 1984 to 2003. [ 14 ]
DE202 was created in 1987; includes nutations and librations. Referred to the dynamical equator and equinox of 2000. Covers late 1899 through 2049. [ 14 ]
DE402 was released in 1995, and was quickly superseded by DE403.
DE403 [ 21 ] was created 1993, released in 1995, expressed in the coordinates of the International Earth Rotation Service (IERS) reference frame, essentially the ICRF. The data compiled by JPL to derive the ephemeris began to move away from limited-accuracy telescopic observations and more toward higher-accuracy radar-ranging of the planets, radio-ranging of spacecraft, and very-long-baseline-interferometric (VLBI) observations of spacecraft, especially for the four inner planets. Telescopic observations remained important for the outer planets because of their distance, hence the inability to bounce radar off of them, and the difficulty of parking a spacecraft near them. The perturbations of 300 asteroids were included, vs DE118/DE200 which included only the five asteroids determined to cause the largest perturbations. Better values of the planets' masses had been found since DE118/DE200, further refining the perturbations. Lunar Laser Ranging accuracy was improved, giving better positions of the Moon. DE403 covered the time span early 1599 to mid 2199. [ 22 ]
DE404 [ 23 ] was released in 1996. A so-called Long Ephemeris, this condensed version of DE403 covered 3000 BC to AD 3000. While both DE403 and DE404 were integrated over the same timespan, the interpolation of DE404 was somewhat reduced in accuracy and nutation of the Earth and libration of the Moon were not included.
DE405 [ 24 ] was released in 1998. It added several years' extra data from telescopic, radar, spacecraft, and VLBI observations (of the Galileo spacecraft at Jupiter, in particular). The method of modeling the asteroids' perturbations was improved, although the same number of asteroids were modeled. The ephemeris was more accurately oriented onto the ICRF. DE405 covered 1600 to 2200 to full precision. This ephemeris was utilized in the Astronomical Almanac from 2003 until 2014.
DE406 was released with DE405 in 1998. A Long Ephemeris, this was the condensed version of DE405, covering 3000 BC to AD 3000 with the same limitations as DE404. This is the same integration as DE405, with the accuracy of the interpolating polynomials has been lessened to reduce file size for the longer time span covered by the file.
DE407 [ 25 ] was apparently unreleased. Details in readily-available sources are sketchy.
DE408 [ 26 ] was an unreleased ephemeris, created in 2005 as a longer version of DE406, covering 20,000 years.
DE409 [ 27 ] was released in 2003 for the Mars Exploration Rover spacecraft arrival at Mars and the Cassini arrival at Saturn. Further spacecraft ranging and VLBI (to the Mars Global Surveyor , Mars Pathfinder and the Mars Odyssey spacecraft) and telescopic data were included in the fit. The orbits of the Pioneer and Voyager spacecraft were reprocessed to give data points for Saturn. These resulted in improvements over DE405, especially to the predicted positions of Mars and Saturn. DE409 covered the years 1901 to 2019.
DE410 [ 28 ] was also released in 2003 covered 1901 - 2019, with improvements from DE409 in the masses for Venus, Mars, Jupiter, Saturn and the Earth-Moon system based on recent research. Though the masses had not yet been adopted by the IAU . The ephemerides were created to support the arrivals of the MER and Cassini spacecraft.
DE411 [ 29 ] was widely cited in the astronomical community, but not publicly released by JPL
DE412 [ 30 ] was widely cited in the astronomical community, but not publicly released by JPL
DE413 [ 29 ] was released in 2004 with updated ephemeris of Pluto in support of the occultation of a star by its satellite Charon on 11 Jul 2005. DE413 was fit to new CCD telescopic observations of Pluto in order to give improved positions of the planet and its moon.
DE414 [ 31 ] was created in 2005 and released in 2006. The numerical integration software was updated to use quadruple-precision for the Newtonian part of the equations of motion . Ranging data to the Mars Global Surveyor and Mars Odyssey spacecraft were extended to 2005, and further CCD observations of the five outer planets were included in the fit. Some data was accidentally left out of the fit, namely Magellan Venus data for 1992-94 and Galileo Jupiter data for 1996-97. Some ranging data to the NEAR Shoemaker spacecraft orbiting the asteroid Eros was used to derive the Earth/Moon mass ratio. DE414 covered the years 1599 to 2201.
DE418 [ 32 ] was released in 2007 for planning the New Horizons mission to Pluto. New observations of Pluto, which took advantage of the new astrometric accuracy of the Hipparcos star catalog, were included in the fit. Mars spacecraft ranging and VLBI observations were updated through 2007. Asteroid masses were estimated differently. Lunar laser ranging data for the Moon was added for the first time since DE403, significantly improving the lunar orbit and librations. Estimated position data from the Cassini spacecraft was included in the fit, improving the orbit of Saturn, but rigorous analysis of the data was deferred to a later date. DE418 covered the years 1899 to 2051, and JPL recommended not using it outside of that range due to minor inconsistencies which remained in the planets' masses due to time constraints.
DE421 [ 33 ] was released in 2008. It included additional ranging and VLBI measurements of Mars spacecraft, new ranging and VLBI of the Venus Express spacecraft, the latest estimates of planetary masses, additional lunar laser ranging, and two more months of CCD measurements of Pluto. When initially released in 2008, the DE421 ephemeris covered the years 1900 to 2050. An additional data release in 2013 extended the coverage to the year 2200.
DE422 [ 34 ] was created in 2009 for the MESSENGER mission to Mercury. A Long Ephemeris, it was intended to replace DE406, covering 3000 BC to AD 3000.
DE423 [ 35 ] was released in 2010. Position estimates of the MESSENGER spacecraft and additional range and VLBI data from the Venus Express spacecraft were fit. DE423 covered the years 1799 to 2200.
DE424 [ 36 ] was created in 2011 to support the Mars Science Laboratory mission.
DE430 [ 37 ] was created in 2013 and Is intended for use in analyzing modern data. It covers the dates 1550 January 1 to 2650 January 22 with the most accurate lunar ephemeris. From 2015 onwards this ephemeris is utilized in the Astronomical Almanac . Beginning with this release only Mars' Barycenter was included due to the small masses of its moons Phobos and Deimos which create a very small offset from the planet's center. [ 38 ] The complete ephemerides files is 128 megabytes but several alternative versions have been made available by JPL [ 10 ]
DE431 [ 37 ] was created in 2013 and is intended for analysis of earlier historical observations of the Sun, Moon, and planets. It covers a longer time span than DE430 (13201 BC to AD 17191) agreeing with DE430 within 1 meter over the time period covered by DE430. Position of the Moon is accurate within 20 meters between 1913-2113 and that error grows quadratically outside of that range. [ 39 ] It is the largest of the ephemerides files at 3.4 gigabytes. [ 40 ]
DE432 [ 41 ] was created April 2014. It includes librations but no nutations. DE432 is a minor update to DE430, and is intended primarily to aid the New Horizons project targeting of Pluto. [ 42 ]
DE436 [ 43 ] was created in 2016 and was based on the DE430, with improved orbital data for Jupiter specifically for the Juno mission).
DE438 [ 44 ] was created in 2018 and was based on the DE430, with improved orbital data for Mercury (for the MESSENGER mission ), Mars (for the Mars Odyssey and Mars Reconnaissance Orbiters ), and Jupiter (for Juno ) . | https://en.wikipedia.org/wiki/Jet_Propulsion_Laboratory_Development_Ephemeris |
Jet aerators are applied across a wide range of water, wastewater and biosolids treatment applications. Their primary purpose is to transfer oxygen to the liquid or sludge. A Jet aerator works through aspirating technology by simultaneously introducing large volumes of high kinetic energy liquid and air through one or more jet nozzles. The high velocity liquid exits the inner, primary jet and rapidly mixes with the incoming air in the outer jet. This intense mixing and high degree of turbulence in the gas/liquid cloud travels outward from the jet along the basin floor prior to the vertical rise of the gas bubble column to the liquid surface.
In most industrial wastewater and biosolids applications jet aerators exhibit superior oxygen transfer efficiency compared to other aeration technologies. The hydrodynamic conditions within the jet and fine bubble cloud produces continuous surface renewal at the gas/liquid interface resulting in higher alpha factors. This results in superior process oxygen transfer performance in the presence of surfactants, extracellular enzymes and high MLS concentrations.
Jet aerators do not require any external air source (i.e. compressor), except for the surrounding atmosphere. Jet aerators can be installed either as submersible units or piped through the tank wall using an external dry-installed chopper pump to feed the aspirating ejector(s). Jet aerators are easily configured into any basin geometry including circular, rectangular, looped reactors and sloped wall basins. Jet aerators are ideally suited for deep tank processes. The jet oxidation ditch is an example of technology innovation where the combination of a deeper basin design, bottom to top mixing and conservation of momentum combines to make a very efficient treatment process. In this and other applications the independent control of oxygen transfer and mixing is a valuable feature for both process control and energy savings. | https://en.wikipedia.org/wiki/Jet_aerators |
In differential topology , the jet bundle is a certain construction that makes a new smooth fiber bundle out of a given smooth fiber bundle. It makes it possible to write differential equations on sections of a fiber bundle in an invariant form. Jets may also be seen as the coordinate free versions of Taylor expansions .
Historically, jet bundles are attributed to Charles Ehresmann , and were an advance on the method ( prolongation ) of Élie Cartan , of dealing geometrically with higher derivatives , by imposing differential form conditions on newly introduced formal variables. Jet bundles are sometimes called sprays , although sprays usually refer more specifically to the associated vector field induced on the corresponding bundle (e.g., the geodesic spray on Finsler manifolds .)
Since the early 1980s, jet bundles have appeared as a concise way to describe phenomena associated with the derivatives of maps, particularly those associated with the calculus of variations . [ 1 ] Consequently, the jet bundle is now recognized as the correct domain for a geometrical covariant field theory and much work is done in general relativistic formulations of fields using this approach.
Suppose M is an m -dimensional manifold and that ( E , π, M ) is a fiber bundle . For p ∈ M , let Γ(p) denote the set of all local sections whose domain contains p . Let I = ( I ( 1 ) , I ( 2 ) , . . . , I ( m ) ) {\displaystyle I=(I(1),I(2),...,I(m))} be a multi-index (an m -tuple of non-negative integers, not necessarily in ascending order), then define:
Define the local sections σ, η ∈ Γ(p) to have the same r -jet at p if
The relation that two maps have the same r -jet is an equivalence relation . An r -jet is an equivalence class under this relation, and the r -jet with representative σ is denoted j p r σ {\displaystyle j_{p}^{r}\sigma } . The integer r is also called the order of the jet, p is its source and σ( p ) is its target .
The r -th jet manifold of π is the set
We may define projections π r and π r ,0 called the source and target projections respectively, by
If 1 ≤ k ≤ r , then the k -jet projection is the function π r,k defined by
{ π r , k : J r ( π ) → J k ( π ) j p r σ ↦ j p k σ {\displaystyle {\begin{cases}\pi _{r,k}:J^{r}(\pi )\to J^{k}(\pi )\\j_{p}^{r}\sigma \mapsto j_{p}^{k}\sigma \end{cases}}}
From this definition, it is clear that π r = π o π r ,0 and that if 0 ≤ m ≤ k , then π r,m = π k,m o π r,k . It is conventional to regard π r,r as the identity map on J r ( π ) and to identify J 0 ( π ) with E .
The functions π r,k , π r ,0 and π r are smooth surjective submersions .
A coordinate system on E will generate a coordinate system on J r ( π ). Let ( U , u ) be an adapted coordinate chart on E , where u = ( x i , u α ). The induced coordinate chart ( U r , u r ) on J r ( π ) is defined by
U r = { j p r σ : p ∈ M , σ ( p ) ∈ U } u r = ( x i , u α , u I α ) {\displaystyle {\begin{aligned}U^{r}&=\left\{j_{p}^{r}\sigma :p\in M,\sigma (p)\in U\right\}\\u^{r}&=\left(x^{i},u^{\alpha },u_{I}^{\alpha }\right)\end{aligned}}}
where
x i ( j p r σ ) = x i ( p ) u α ( j p r σ ) = u α ( σ ( p ) ) {\displaystyle {\begin{aligned}x^{i}\left(j_{p}^{r}\sigma \right)&=x^{i}(p)\\u^{\alpha }\left(j_{p}^{r}\sigma \right)&=u^{\alpha }(\sigma (p))\end{aligned}}}
and the n ( ( m + r r ) − 1 ) {\displaystyle n\left({\binom {m+r}{r}}-1\right)} functions known as the derivative coordinates :
{ u I α : U k → R u I α ( j p r σ ) = ∂ | I | σ α ∂ x I | p {\displaystyle {\begin{cases}u_{I}^{\alpha }:U^{k}\to \mathbf {R} \\u_{I}^{\alpha }\left(j_{p}^{r}\sigma \right)=\left.{\frac {\partial ^{|I|}\sigma ^{\alpha }}{\partial x^{I}}}\right|_{p}\end{cases}}}
Given an atlas of adapted charts ( U , u ) on E , the corresponding collection of charts ( U r , u r ) is a finite-dimensional C ∞ atlas on J r ( π ).
Since the atlas on each J r ( π ) {\displaystyle J^{r}(\pi )} defines a manifold, the triples ( J r ( π ) , π r , k , J k ( π ) ) {\displaystyle (J^{r}(\pi ),\pi _{r,k},J^{k}(\pi ))} , ( J r ( π ) , π r , 0 , E ) {\displaystyle (J^{r}(\pi ),\pi _{r,0},E)} and ( J r ( π ) , π r , M ) {\displaystyle (J^{r}(\pi ),\pi _{r},M)} all define fibered manifolds. In particular, if ( E , π , M ) {\displaystyle (E,\pi ,M)} is a fiber bundle, the triple ( J r ( π ) , π r , M ) {\displaystyle (J^{r}(\pi ),\pi _{r},M)} defines the r -th jet bundle of π .
If W ⊂ M is an open submanifold, then
If p ∈ M , then the fiber π r − 1 ( p ) {\displaystyle \pi _{r}^{-1}(p)\,} is denoted J p r ( π ) {\displaystyle J_{p}^{r}(\pi )} .
Let σ be a local section of π with domain W ⊂ M . The r -th jet prolongation of σ is the map j r σ : W → J r ( π ) {\displaystyle j^{r}\sigma :W\rightarrow J^{r}(\pi )} defined by
Note that π r ∘ j r σ = i d W {\displaystyle \pi _{r}\circ j^{r}\sigma =\mathbb {id} _{W}} , so j r σ {\displaystyle j^{r}\sigma } really is a section. In local coordinates, j r σ {\displaystyle j^{r}\sigma } is given by
We identify j 0 σ {\displaystyle j^{0}\sigma } with σ {\displaystyle \sigma } .
An independently motivated construction of the sheaf of sections Γ J k ( π T M ) {\displaystyle \Gamma J^{k}\left(\pi _{TM}\right)} is given .
Consider a diagonal map Δ n : M → ∏ i = 1 n + 1 M {\textstyle \Delta _{n}:M\to \prod _{i=1}^{n+1}M} , where the smooth manifold M {\displaystyle M} is a locally ringed space by C k ( U ) {\displaystyle C^{k}(U)} for each open U {\displaystyle U} . Let I {\displaystyle {\mathcal {I}}} be the ideal sheaf of Δ n ( M ) {\displaystyle \Delta _{n}(M)} , equivalently let I {\displaystyle {\mathcal {I}}} be the sheaf of smooth germs which vanish on Δ n ( M ) {\displaystyle \Delta _{n}(M)} for all 0 < n ≤ k {\displaystyle 0<n\leq k} . The pullback of the quotient sheaf Δ n ∗ ( I / I n + 1 ) {\displaystyle {\Delta _{n}}^{*}\left({\mathcal {I}}/{\mathcal {I}}^{n+1}\right)} from ∏ i = 1 n + 1 M {\textstyle \prod _{i=1}^{n+1}M} to M {\displaystyle M} by Δ n {\displaystyle \Delta _{n}} is the sheaf of k-jets. [ 2 ]
The direct limit of the sequence of injections given by the canonical inclusions I n + 1 ↪ I n {\displaystyle {\mathcal {I}}^{n+1}\hookrightarrow {\mathcal {I}}^{n}} of sheaves, gives rise to the infinite jet sheaf J ∞ ( T M ) {\displaystyle {\mathcal {J}}^{\infty }(TM)} . Observe that by the direct limit construction it is a filtered ring.
If π is the trivial bundle ( M × R , pr 1 , M ), then there is a canonical diffeomorphism between the first jet bundle J 1 ( π ) {\displaystyle J^{1}(\pi )} and T*M × R . To construct this diffeomorphism, for each σ in Γ M ( π ) {\displaystyle \Gamma _{M}(\pi )} write σ ¯ = p r 2 ∘ σ ∈ C ∞ ( M ) {\displaystyle {\bar {\sigma }}=pr_{2}\circ \sigma \in C^{\infty }(M)\,} .
Then, whenever p ∈ M
Consequently, the mapping
is well-defined and is clearly injective . Writing it out in coordinates shows that it is a diffeomorphism, because if (x i , u) are coordinates on M × R , where u = id R is the identity coordinate, then the derivative coordinates u i on J 1 (π) correspond to the coordinates ∂ i on T*M .
Likewise, if π is the trivial bundle ( R × M , pr 1 , R ), then there exists a canonical diffeomorphism between J 1 ( π ) {\displaystyle J^{1}(\pi )} and R × TM .
The space J r (π) carries a natural distribution , that is, a sub-bundle of the tangent bundle TJ r (π)), called the Cartan distribution . The Cartan distribution is spanned by all tangent planes to graphs of holonomic sections; that is, sections of the form j r φ for φ a section of π.
The annihilator of the Cartan distribution is a space of differential one-forms called contact forms , on J r (π). The space of differential one-forms on J r (π) is denoted by Λ 1 J r ( π ) {\displaystyle \Lambda ^{1}J^{r}(\pi )} and the space of contact forms is denoted by Λ C r π {\displaystyle \Lambda _{C}^{r}\pi } . A one form is a contact form provided its pullback along every prolongation is zero. In other words, θ ∈ Λ 1 J r π {\displaystyle \theta \in \Lambda ^{1}J^{r}\pi } is a contact form if and only if
for all local sections σ of π over M .
The Cartan distribution is the main geometrical structure on jet spaces and plays an important role in the geometric theory of partial differential equations . The Cartan distributions are completely non-integrable. In particular, they are not involutive . The dimension of the Cartan distribution grows with the order of the jet space. However, on the space of infinite jets J ∞ the Cartan distribution becomes involutive and finite-dimensional: its dimension coincides with the dimension of the base manifold M .
Consider the case (E, π, M) , where E ≃ R 2 and M ≃ R . Then, (J 1 (π), π, M) defines the first jet bundle, and may be coordinated by (x, u, u 1 ) , where
for all p ∈ M and σ in Γ p (π). A general 1-form on J 1 (π) takes the form
A section σ in Γ p (π) has first prolongation
Hence, (j 1 σ)*θ can be calculated as
This will vanish for all sections σ if and only if c = 0 and a = − bσ′(x) . Hence, θ = b(x, u, u 1 )θ 0 must necessarily be a multiple of the basic contact form θ 0 = du − u 1 dx . Proceeding to the second jet space J 2 (π) with additional coordinate u 2 , such that
a general 1-form has the construction
This is a contact form if and only if
which implies that e = 0 and a = − bσ′(x) − cσ′′(x) . Therefore, θ is a contact form if and only if
where θ 1 = du 1 − u 2 dx is the next basic contact form (Note that here we are identifying the form θ 0 with its pull-back ( π 2 , 1 ) ∗ θ 0 {\displaystyle \left(\pi _{2,1}\right)^{*}\theta _{0}} to J 2 (π) ).
In general, providing x, u ∈ R , a contact form on J r+1 (π) can be written as a linear combination of the basic contact forms
where
Similar arguments lead to a complete characterization of all contact forms.
In local coordinates, every contact one-form on J r+1 (π) can be written as a linear combination
with smooth coefficients P i α ( x i , u α , u I α ) {\displaystyle P_{i}^{\alpha }(x^{i},u^{\alpha },u_{I}^{\alpha })} of the basic contact forms
|I| is known as the order of the contact form θ i α {\displaystyle \theta _{i}^{\alpha }} . Note that contact forms on J r+1 (π) have orders at most r . Contact forms provide a characterization of those local sections of π r+1 which are prolongations of sections of π.
Let ψ ∈ Γ W ( π r+1 ), then ψ = j r+1 σ where σ ∈ Γ W (π) if and only if ψ ∗ ( θ | W ) = 0 , ∀ θ ∈ Λ C 1 π r + 1 , r . {\displaystyle \psi ^{*}(\theta |_{W})=0,\forall \theta \in \Lambda _{C}^{1}\pi _{r+1,r}.\,}
A general vector field on the total space E , coordinated by ( x , u ) = d e f ( x i , u α ) {\displaystyle (x,u)\mathrel {\stackrel {\mathrm {def} }{=}} \left(x^{i},u^{\alpha }\right)\,} , is
A vector field is called horizontal , meaning that all the vertical coefficients vanish, if ϕ α {\displaystyle \phi ^{\alpha }} = 0.
A vector field is called vertical , meaning that all the horizontal coefficients vanish, if ρ i = 0.
For fixed (x, u) , we identify
having coordinates (x, u, ρ i , φ α ) , with an element in the fiber T xu E of TE over (x, u) in E , called a tangent vector in TE . A section
is called a vector field on E with
and ψ in Γ(TE) .
The jet bundle J r (π) is coordinated by ( x , u , w ) = d e f ( x i , u α , w i α ) {\displaystyle (x,u,w)\mathrel {\stackrel {\mathrm {def} }{=}} \left(x^{i},u^{\alpha },w_{i}^{\alpha }\right)\,} . For fixed (x, u, w) , identify
having coordinates
with an element in the fiber T x u w ( J r π ) {\displaystyle T_{xuw}(J^{r}\pi )} of TJ r (π) over (x, u, w) ∈ J r (π) , called a tangent vector in TJ r (π) . Here,
are real-valued functions on J r (π) . A section
is a vector field on J r (π) , and we say Ψ ∈ Γ ( T ( J r π ) ) . {\displaystyle \Psi \in \Gamma (T\left(J^{r}\pi \right)).}
Let (E, π, M) be a fiber bundle. An r -th order partial differential equation on π is a closed embedded submanifold S of the jet manifold J r (π) . A solution is a local section σ ∈ Γ W (π) satisfying j p r σ ∈ S {\displaystyle j_{p}^{r}\sigma \in S} , for all p in M .
Consider an example of a first order partial differential equation.
Let π be the trivial bundle ( R 2 × R , pr 1 , R 2 ) with global coordinates ( x 1 , x 2 , u 1 ). Then the map F : J 1 (π) → R defined by
gives rise to the differential equation
which can be written
The particular
has first prolongation given by
and is a solution of this differential equation, because
and so j p 1 σ ∈ S {\displaystyle j_{p}^{1}\sigma \in S} for every p ∈ R 2 .
A local diffeomorphism ψ : J r ( π ) → J r ( π ) defines a contact transformation of order r if it preserves the contact ideal, meaning that if θ is any contact form on J r ( π ), then ψ*θ is also a contact form.
The flow generated by a vector field V r on the jet space J r (π) forms a one-parameter group of contact transformations if and only if the Lie derivative L V r ( θ ) {\displaystyle {\mathcal {L}}_{V^{r}}(\theta )} of any contact form θ preserves the contact ideal.
Let us begin with the first order case. Consider a general vector field V 1 on J 1 ( π ), given by
We now apply L V 1 {\displaystyle {\mathcal {L}}_{V^{1}}} to the basic contact forms θ 0 α = d u α − u i α d x i , {\displaystyle \theta _{0}^{\alpha }=du^{\alpha }-u_{i}^{\alpha }dx^{i},} and expand the exterior derivative of the functions in terms of their coordinates to obtain:
Therefore, V 1 determines a contact transformation if and only if the coefficients of dx i and d u i k {\displaystyle du_{i}^{k}} in the formula vanish. The latter requirements imply the contact conditions
The former requirements provide explicit formulae for the coefficients of the first derivative terms in V 1 :
where
denotes the zeroth order truncation of the total derivative D i .
Thus, the contact conditions uniquely prescribe the prolongation of any point or contact vector field. That is, if L V r {\displaystyle {\mathcal {L}}_{V^{r}}} satisfies these equations, V r is called the r -th prolongation of V to a vector field on J r (π) .
These results are best understood when applied to a particular example. Hence, let us examine the following.
Consider the case (E, π, M) , where E ≅ R 2 and M ≃ R . Then, (J 1 (π), π, E) defines the first jet bundle, and may be coordinated by (x, u, u 1 ) , where
for all p ∈ M and σ in Γ p ( π ). A contact form on J 1 (π) has the form
Consider a vector V on E , having the form
Then, the first prolongation of this vector field to J 1 (π) is
If we now take the Lie derivative of the contact form with respect to this prolonged vector field, L V 1 ( θ ) , {\displaystyle {\mathcal {L}}_{V^{1}}(\theta ),} we obtain
Hence, for preservation of the contact ideal, we require
And so the first prolongation of V to a vector field on J 1 (π) is
Let us also calculate the second prolongation of V to a vector field on J 2 (π) . We have { x , u , u 1 , u 2 } {\displaystyle \{x,u,u_{1},u_{2}\}} as coordinates on J 2 (π) . Hence, the prolonged vector has the form
The contact forms are
To preserve the contact ideal, we require
Now, θ has no u 2 dependency. Hence, from this equation we will pick up the formula for ρ , which will necessarily be the same result as we found for V 1 . Therefore, the problem is analogous to prolonging the vector field V 1 to J 2 (π). That is to say, we may generate the r -th prolongation of a vector field by recursively applying the Lie derivative of the contact forms with respect to the prolonged vector fields, r times. So, we have
and so
Therefore, the Lie derivative of the second contact form with respect to V 2 is
Hence, for L V 2 ( θ 1 ) {\displaystyle {\mathcal {L}}_{V^{2}}(\theta _{1})} to preserve the contact ideal, we require
And so the second prolongation of V to a vector field on J 2 (π) is
Note that the first prolongation of V can be recovered by omitting the second derivative terms in V 2 , or by projecting back to J 1 (π) .
The inverse limit of the sequence of projections π k + 1 , k : J k + 1 ( π ) → J k ( π ) {\displaystyle \pi _{k+1,k}:J^{k+1}(\pi )\to J^{k}(\pi )} gives rise to the infinite jet space J ∞ (π) . A point j p ∞ ( σ ) {\displaystyle j_{p}^{\infty }(\sigma )} is the equivalence class of sections of π that have the same k -jet in p as σ for all values of k . The natural projection π ∞ maps j p ∞ ( σ ) {\displaystyle j_{p}^{\infty }(\sigma )} into p .
Just by thinking in terms of coordinates, J ∞ (π) appears to be an infinite-dimensional geometric object. In fact, the simplest way of introducing a differentiable structure on J ∞ (π) , not relying on differentiable charts, is given by the differential calculus over commutative algebras . Dual to the sequence of projections π k + 1 , k : J k + 1 ( π ) → J k ( π ) {\displaystyle \pi _{k+1,k}:J^{k+1}(\pi )\to J^{k}(\pi )} of manifolds is the sequence of injections π k + 1 , k ∗ : C ∞ ( J k ( π ) ) → C ∞ ( J k + 1 ( π ) ) {\displaystyle \pi _{k+1,k}^{*}:C^{\infty }(J^{k}(\pi ))\to C^{\infty }\left(J^{k+1}(\pi )\right)} of commutative algebras. Let's denote C ∞ ( J k ( π ) ) {\displaystyle C^{\infty }(J^{k}(\pi ))} simply by F k ( π ) {\displaystyle {\mathcal {F}}_{k}(\pi )} . Take now the direct limit F ( π ) {\displaystyle {\mathcal {F}}(\pi )} of the F k ( π ) {\displaystyle {\mathcal {F}}_{k}(\pi )} 's. It will be a commutative algebra, which can be assumed to be the smooth functions algebra over the geometric object J ∞ (π) . Observe that F ( π ) {\displaystyle {\mathcal {F}}(\pi )} , being born as a direct limit, carries an additional structure: it is a filtered commutative algebra.
Roughly speaking, a concrete element φ ∈ F ( π ) {\displaystyle \varphi \in {\mathcal {F}}(\pi )} will always belong to some F k ( π ) {\displaystyle {\mathcal {F}}_{k}(\pi )} , so it is a smooth function on the finite-dimensional manifold J k (π) in the usual sense.
Given a k -th order system of PDEs E ⊆ J k (π) , the collection I(E) of vanishing on E smooth functions on J ∞ (π) is an ideal in the algebra F k ( π ) {\displaystyle {\mathcal {F}}_{k}(\pi )} , and hence in the direct limit F ( π ) {\displaystyle {\mathcal {F}}(\pi )} too.
Enhance I(E) by adding all the possible compositions of total derivatives applied to all its elements. This way we get a new ideal I of F ( π ) {\displaystyle {\mathcal {F}}(\pi )} which is now closed under the operation of taking total derivative. The submanifold E (∞) of J ∞ (π) cut out by I is called the infinite prolongation of E .
Geometrically, E (∞) is the manifold of formal solutions of E . A point j p ∞ ( σ ) {\displaystyle j_{p}^{\infty }(\sigma )} of E (∞) can be easily seen to be represented by a section σ whose k -jet's graph is tangent to E at the point j p k ( σ ) {\displaystyle j_{p}^{k}(\sigma )} with arbitrarily high order of tangency.
Analytically, if E is given by φ = 0, a formal solution can be understood as the set of Taylor coefficients of a section σ in a point p that make vanish the Taylor series of φ ∘ j k ( σ ) {\displaystyle \varphi \circ j^{k}(\sigma )} at the point p .
Most importantly, the closure properties of I imply that E (∞) is tangent to the infinite-order contact structure C {\displaystyle {\mathcal {C}}} on J ∞ (π) , so that by restricting C {\displaystyle {\mathcal {C}}} to E (∞) one gets the diffiety ( E ( ∞ ) , C | E ( ∞ ) ) {\displaystyle (E_{(\infty )},{\mathcal {C}}|_{E_{(\infty )}})} , and can study the associated Vinogradov (C-spectral) sequence .
This article has defined jets of local sections of a bundle, but it is possible to define jets of functions f: M → N , where M and N are manifolds; the jet of f then just corresponds to the jet of the section
( gr f is known as the graph of the function f ) of the trivial bundle ( M × N , π 1 , M ). However, this restriction does not simplify the theory, as the global triviality of π does not imply the global triviality of π 1 . | https://en.wikipedia.org/wiki/Jet_bundle |
In mass spectrometry , jet disrupters are specialized electrodes within ion funnels that counteract the effects of directed gas flow. Acting as physical barriers to neutral molecules , they disperse gas molecules and charged droplets while improving ion transmission and reducing vacuum system demands. [ 1 ] [ 2 ] [ 3 ]
The development of the jet disrupter stemmed from the discovery that directed gas flow continued beyond both the capillary inlet and the ion funnel exit. This persistence caused inaccurate pressure readings, contamination of mass spectrometer components, increased background noise, and placed greater demand on downstream vacuum pumps. [ 4 ] [ 5 ] To address these challenges posed by non-uniform gas pressures within ion funnels, the jet disrupter was introduced. [ 6 ]
The first jet disrupter was developed by Taeman Kim, consisting of a 9-mm brass disk positioned 22 mm downstream of the first ion funnel electrode. Operating at a higher voltage than the adjacent ring electrodes, this configuration enabled ions to be deflected around the electrode while causing neutral molecules and charged droplets to disperse and more efficiently be removed by vacuum pumps. Implementation of the jet disrupter in ion funnels yielded several improvements: downstream vacuum chamber pressure was reduced by a factor of 2-3, ion transmission improved by 15%, and MS/MS spectra demonstrated enhanced signal-to-noise ratios , increasing between 5.3 and 14.1-fold (depending on sample concentrations). [ 7 ]
Furthermore, jet disrupters can function as ion valves. By modulating the applied voltage, it is possible to control the transmission efficiency of ions through the funnel. This capability is particularly valuable for reducing the relative intensity of highly abundant analyte ions, which can rapidly fill ion trap analyzers and cause unwanted space charging effects, which occur when excessive ion populations degrade mass analyzer performance. Their application into ion cyclotron resonance (ICR) cells helped maintain optimal ion populations, improving mass accuracy and sensitivity. [ 8 ] The valve-like properties have also proven beneficial in dual-channel ion funnel designs, where a jet disrupter can modulate the flow of ions from one channel without affecting the ion transmission efficiency of the other. [ 9 ]
While jet disrupters effectively manage directed gas flow and improve ion transmission, they face several operational challenges. Over time, the electrode surface becomes contaminated through exposure to liquid droplets and neutral molecules. Moreover, since jet disrupters cannot completely block these particles, some inevitably pass through to downstream components of the mass spectrometer, gradually degrading signal quality and necessitating periodic maintenance or cleaning. [ 10 ]
An alternative approach involves orthogonal ion injection, where the capillary input is orthogonally aligned with the ion funnel axis. Instead of using a physical barrier like a jet disrupter, this configuration allows the ion funnel to capture ions while naturally directing gas flow toward an outlet away from the funnel. This design effectively separates the gas dynamics from the ion path while maintaining ion transmission. [ 11 ] | https://en.wikipedia.org/wiki/Jet_disrupter |
A jet engine is a type of reaction engine , discharging a fast-moving jet of heated gas (usually air) that generates thrust by jet propulsion . While this broad definition may include rocket , water jet , and hybrid propulsion, the term jet engine typically refers to an internal combustion air-breathing jet engine such as a turbojet , turbofan , ramjet , pulse jet , or scramjet . In general, jet engines are internal combustion engines .
Air-breathing jet engines typically feature a rotating air compressor powered by a turbine , with the leftover power providing thrust through the propelling nozzle —this process is known as the Brayton thermodynamic cycle . Jet aircraft use such engines for long-distance travel. Early jet aircraft used turbojet engines that were relatively inefficient for subsonic flight. Most modern subsonic jet aircraft use more complex high-bypass turbofan engines . They give higher speed and greater fuel efficiency than piston and propeller aeroengines over long distances. A few air-breathing engines made for high-speed applications (ramjets and scramjets ) use the ram effect of the vehicle's speed instead of a mechanical compressor.
The thrust of a typical jetliner engine went from 5,000 lbf (22 kN) ( de Havilland Ghost turbojet) in the 1950s to 115,000 lbf (510 kN) ( General Electric GE90 turbofan) in the 1990s, and their reliability went from 40 in-flight shutdowns per 100,000 engine flight hours to less than 1 per 100,000 in the late 1990s. This, combined with greatly decreased fuel consumption, permitted routine transatlantic flight by twin-engined airliners by the turn of the century, where previously a similar journey would have required multiple fuel stops. [ 1 ]
The principle of the jet engine is not new; however, the technical advances necessary to make the idea work did not come to fruition until the 20th century.
A rudimentary demonstration of jet power dates back to the aeolipile , a device described by Hero of Alexandria in 1st-century Egypt . This device directed steam power through two nozzles to cause a sphere to spin rapidly on its axis. It was seen as a curiosity. Meanwhile, practical applications of the turbine can be seen in the water wheel and the windmill .
Historians have further traced the theoretical origin of the principles of jet engines to traditional Chinese firework and rocket propulsion systems. Such devices' use for flight is documented in the story of Ottoman soldier Lagâri Hasan Çelebi , who reportedly achieved flight using a cone-shaped rocket in 1633. [ 2 ]
The earliest attempts at airbreathing jet engines were hybrid designs in which an external power source first compressed air, which was then mixed with fuel and burned for jet thrust. The Italian Caproni Campini N.1 , and the Japanese Tsu-11 engine intended to power Ohka kamikaze planes towards the end of World War II were unsuccessful.
Even before the start of World War II, engineers were beginning to realize that engines driving propellers were approaching limits due to issues related to propeller efficiency, [ 3 ] which declined as blade tips approached the speed of sound . If aircraft performance were to increase beyond such a barrier, a different propulsion mechanism was necessary. This was the motivation behind the development of the gas turbine engine, the most common form of jet engine.
The key to a practical jet engine was the gas turbine , extracting power from the engine itself to drive the compressor . The gas turbine was not a new idea: the patent for a stationary turbine was granted to John Barber in England in 1791. The first gas turbine to successfully run self-sustaining was built in 1903 by Norwegian engineer Ægidius Elling . [ 4 ] Such engines did not reach manufacture due to issues of safety, reliability, weight and, especially, sustained operation.
The first patent for using a gas turbine to power an aircraft was filed in 1921 by Maxime Guillaume . [ 5 ] [ 6 ] His engine was an axial-flow turbojet, but was never constructed, as it would have required considerable advances over the state of the art in compressors. Alan Arnold Griffith published An Aerodynamic Theory of Turbine Design in 1926 leading to experimental work at the RAE .
In 1928, RAF College Cranwell cadet Frank Whittle formally submitted his ideas for a turbojet to his superiors. [ 7 ] In October 1929, he developed his ideas further. [ 8 ] On 16 January 1930, in England, Whittle submitted his first patent (granted in 1932). [ 9 ] The patent showed a two-stage axial compressor feeding a single-sided centrifugal compressor . Practical axial compressors were made possible by ideas from A.A.Griffith in a seminal paper in 1926 ("An Aerodynamic Theory of Turbine Design"). Whittle would later concentrate on the simpler centrifugal compressor only. Whittle was unable to interest the government in his invention, and development continued at a slow pace.
In Spain, pilot and engineer Virgilio Leret Ruiz was granted a patent for a jet engine design in March 1935. Republican president Manuel Azaña arranged for initial construction at the Hispano-Suiza aircraft factory in Madrid in 1936, but Leret was executed months later by Francoist Moroccan troops after unsuccessfully defending his seaplane base on the first days of the Spanish Civil War . His plans, hidden from Francoists, were secretly given to the British embassy in Madrid a few years later by his wife, Carlota O'Neill , upon her release from prison. [ 10 ] [ 11 ]
In 1935, Hans von Ohain started work on a similar design to Whittle's in Germany, both compressor and turbine being radial, on opposite sides of the same disc, initially unaware of Whittle's work. [ 12 ] Von Ohain's first device was strictly experimental and could run only under external power, but he was able to demonstrate the basic concept. Ohain was then introduced to Ernst Heinkel , one of the larger aircraft industrialists of the day, who immediately saw the promise of the design. Heinkel had recently purchased the Hirth engine company, and Ohain and his master machinist Max Hahn were set up there as a new division of the Hirth company. They had their first HeS 1 centrifugal engine running by September 1937. Unlike Whittle's design, Ohain used hydrogen as fuel, supplied under external pressure. Their subsequent designs culminated in the gasoline -fuelled HeS 3 of 5 kN (1,100 lbf), which was fitted to Heinkel's simple and compact He 178 airframe and flown by Erich Warsitz in the early morning of August 27, 1939, from Rostock -Marienehe aerodrome , an impressively short time for development. The He 178 was the world's first jet plane. [ 13 ] Heinkel applied for a US patent covering the Aircraft Power Plant by Hans Joachim Pabst von Ohain on May 31, 1939; patent number US2256198, with M Hahn referenced as inventor. Von Ohain's design, an axial-flow engine, as opposed to Whittle's centrifugal flow engine, was eventually adopted by most manufacturers by the 1950s. [ 14 ] [ 15 ]
Austrian Anselm Franz of Junkers ' engine division ( Junkers Motoren or "Jumo") introduced the axial-flow compressor in their jet engine. Jumo was assigned the next engine number in the RLM 109-0xx numbering sequence for gas turbine aircraft powerplants, "004", and the result was the Jumo 004 engine. After many lesser technical difficulties were solved, mass production of this engine started in 1944 as a powerplant for the world's first jet- fighter aircraft , the Messerschmitt Me 262 (and later the world's first jet- bomber aircraft, the Arado Ar 234 ). A variety of reasons conspired to delay the engine's availability, causing the fighter to arrive too late to improve Germany's position in World War II , however this was the first jet engine to be used in service.
Meanwhile, in Britain the Gloster E28/39 had its maiden flight on 15 May 1941 and the Gloster Meteor finally entered service with the RAF in July 1944. These were powered by turbojet engines from Power Jets Ltd., set up by Frank Whittle. The first two operational turbojet aircraft, the Messerschmitt Me 262 and then the Gloster Meteor entered service within three months of each other in 1944; the Me 262 in April and the Gloster Meteor in July. The Meteor only saw around 15 aircraft enter World War II action, while up to 1400 Me 262 were produced, with 300 entering combat, delivering the first ground attacks and air combat victories of jet planes. [ 16 ] [ 17 ] [ 18 ]
Following the end of the war the German jet aircraft and jet engines were extensively studied by the victorious allies and contributed to work on early Soviet and US jet fighters. The legacy of the axial-flow engine is seen in the fact that practically all jet engines on fixed-wing aircraft have had some inspiration from this design.
By the 1950s, the jet engine was almost universal in combat aircraft, with the exception of cargo, liaison and other specialty types. By this point, some of the British designs were already cleared for civilian use, and had appeared on early models like the de Havilland Comet and Avro Canada Jetliner . By the 1960s, all large civilian aircraft were also jet powered, leaving the piston engine in low-cost niche roles such as cargo flights.
The efficiency of turbojet engines was still rather worse than piston engines, but by the 1970s, with the advent of high-bypass turbofan jet engines (an innovation not foreseen by the early commentators such as Edgar Buckingham , at high speeds and high altitudes that seemed absurd to them), fuel efficiency was about the same as the best piston and propeller engines. [ 19 ]
Jet engines power jet aircraft , cruise missiles and unmanned aerial vehicles . In the form of rocket engines they power model rocketry , spaceflight , and military missiles .
Jet engines have propelled high speed cars, particularly drag racers , with the all-time record held by a rocket car . A turbofan powered car, ThrustSSC , currently holds the land speed record .
Jet engine designs are frequently modified for non-aircraft applications, as industrial gas turbines or marine powerplants . These are used in electrical power generation, for powering water, natural gas, or oil pumps, and providing propulsion for ships and locomotives. Industrial gas turbines can create up to 50,000 shaft horsepower. Many of these engines are derived from older military turbojets such as the Pratt & Whitney J57 and J75 models. There is also a derivative of the P&W JT8D low-bypass turbofan that creates up to 35,000 horsepower (HP)
.
Jet engines are also sometimes developed into, or share certain components such as engine cores, with turboshaft and turboprop engines, which are forms of gas turbine engines that are typically used to power helicopters and some propeller-driven aircraft.
There are a large number of different types of jet engines, all of which achieve forward thrust from the principle of jet propulsion .
Commonly aircraft are propelled by airbreathing jet engines. Most airbreathing jet engines that are in use are turbofan jet engines, which give good efficiency at speeds just below the speed of sound.
A turbojet engine is a gas turbine engine that works by compressing air with an inlet and a compressor ( axial , centrifugal , or both), mixing fuel with the compressed air, burning the mixture in the combustor , and then passing the hot, high pressure air through a turbine and a nozzle . The compressor is powered by the turbine, which extracts energy from the expanding gas passing through it. The engine converts internal energy in the fuel to increased momentum of the gas flowing through the engine, producing thrust. All the air entering the compressor is passed through the combustor, and turbine, unlike the turbofan engine described below. [ 20 ]
Turbofans differ from turbojets in that they have an additional fan at the front of the engine, which accelerates air in a duct bypassing the core gas turbine engine. Turbofans are the dominant engine type for medium and long-range airliners .
Turbofans are usually more efficient than turbojets at subsonic speeds, but at high speeds their large frontal area generates more drag . [ 21 ] Therefore, in supersonic flight, and in military and other aircraft where other considerations have a higher priority than fuel efficiency, fans tend to be smaller or absent.
Because of these distinctions, turbofan engine designs are often categorized as low-bypass or high-bypass , depending upon the amount of air which bypasses the core of the engine. Low-bypass turbofans have a bypass ratio of around 2:1 or less.
A propfan engine is a type of airbreathing jet engine which combines aspects of turboprop and turbofan . Its design consists of a central gas turbine which drives open-air contra-rotating propellers . Unlike turboprop engines, in which the propeller and the engine are considered two separate products, the propfan’s gas generator and its unshrouded propeller module are heavily integrated and are considered to be a single product. [ citation needed ] Additionally, the propfan’s short, heavily twisted variable pitch blades closely remember the ducted fan blades of turbofan engines.
Propfans are designed to offer the speed and performance of turbofan engines with fuel efficiency of turboprops. However, due to low fuel costs and high cabin noise, early propfan projects were abandoned. [ 22 ] Very few aircraft have flown with propfans, with the Antonov An-70 being the first and only aircraft to fly while being powered solely by propfan engines.
The term Advanced technology engine refers to the modern generation of jet engines. [ 23 ] The principle is that a turbine engine will function more efficiently if the various sets of turbines can revolve at their individual optimum speeds, instead of at the same speed. The true advanced technology engine has a triple spool, meaning that instead of having a single drive shaft, there are three, in order that the three sets of blades may revolve at different speeds. An interim state is a twin-spool engine, allowing only two different speeds for the turbines.
Ram compression jet engines are airbreathing engines similar to gas turbine engines in so far as they both use the Brayton cycle . Gas turbine and ram compression engines differ, however, in how they compress the incoming airflow. Whereas gas turbine engines use axial or centrifugal compressors to compress incoming air, ram engines rely only on air compressed in the inlet or diffuser. [ 24 ] A ram engine thus requires a substantial initial forward airspeed before it can function. Ramjets are considered the simplest type of air breathing jet engine because they have no moving parts in the engine proper, only in the accessories. [ 25 ]
Scramjets differ mainly in the fact that the air does not slow to subsonic speeds. Rather, they use supersonic combustion. They are efficient at even higher speed. Very few have been built or flown.
The rocket engine uses the same basic physical principles of thrust as a form of reaction engine , [ 26 ] but is distinct from the jet engine in that it does not require atmospheric air to provide oxygen; the rocket carries all components of the reaction mass. However some definitions treat it as a form of jet propulsion . [ 27 ]
Because rockets do not breathe air, this allows them to operate at arbitrary altitudes and in space. [ 28 ]
This type of engine is used for launching satellites, space exploration and crewed access, and permitted landing on the Moon in 1969.
Rocket engines are used for high altitude flights, or anywhere where very high accelerations are needed since rocket engines themselves have a very high thrust-to-weight ratio .
However, the high exhaust speed and the heavier, oxidizer-rich propellant results in far more propellant use than turbofans. Even so, at extremely high speeds they become energy-efficient.
An approximate equation for the net thrust of a rocket engine is:
Where F N {\displaystyle F_{N}} is the net thrust, I sp,vac {\displaystyle I_{\text{sp,vac}}} is the specific impulse , g 0 {\displaystyle g_{0}} is a standard gravity , m ˙ {\displaystyle {\dot {m}}} is the propellant flow in kg/s, A e {\displaystyle A_{e}} is the cross-sectional area at the exit of the exhaust nozzle, and p {\displaystyle p} is the atmospheric pressure.
Combined-cycle engines simultaneously use two or more different principles of jet propulsion.
A water jet, or pump-jet, is a marine propulsion system that uses a jet of water. The mechanical arrangement may be a ducted propeller with nozzle, or a centrifugal compressor and nozzle. The pump-jet must be driven by a separate engine such as a Diesel or gas turbine .
All jet engines are reaction engines that generate thrust by emitting a jet of fluid rearwards at relatively high speed. The forces on the inside of the engine needed to create this jet give a strong thrust on the engine which pushes the craft forwards.
Jet engines make their jet from propellant stored in tanks that are attached to the engine (as in a 'rocket') as well as in duct engines (those commonly used on aircraft) by ingesting an external fluid (very typically air) and expelling it at higher speed.
A propelling nozzle produces a high velocity exhaust jet . Propelling nozzles turn internal and pressure energy into high velocity kinetic energy. [ 30 ] The total pressure and temperature don't change through the nozzle but their static values drop as the gas speeds up.
The velocity of the air entering the nozzle is low, about Mach 0.4, a prerequisite for minimizing pressure losses in the duct leading to the nozzle. The temperature entering the nozzle may be as low as sea level ambient for a fan nozzle in the cold air at cruise altitudes. It may be as high as the 1000 Kelvin exhaust gas temperature for a supersonic afterburning engine or 2200 K with afterburner lit. [ 31 ] The pressure entering the nozzle may vary from 1.5 times the pressure outside the nozzle, for a single stage fan, to 30 times for the fastest manned aircraft at Mach 3+. [ 32 ]
Convergent nozzles are only able to accelerate the gas up to local sonic (Mach 1) conditions. To reach high flight speeds, even greater exhaust velocities are required, and so a convergent-divergent nozzle is needed on high-speed aircraft. [ 33 ]
The engine thrust is highest if the static pressure of the gas reaches the ambient value as it leaves the nozzle. This only happens if the nozzle exit area is the correct value for the nozzle pressure ratio (npr). Since the npr changes with engine thrust setting and flight speed this is seldom the case. Also at supersonic speeds the divergent area is less than required to give complete internal expansion to ambient pressure as a trade-off with external body drag. Whitford [ 34 ] gives the F-16 as an example. Other underexpanded examples were the XB-70 and SR-71.
The nozzle size, together with the area of the turbine nozzles, determines the operating pressure of the compressor. [ 35 ]
This overview highlights where energy losses occur in complete jet aircraft powerplants or engine installations.
A jet engine at rest, as on a test stand, sucks in fuel and generates thrust. How well it does this is judged by how much fuel it uses and what force is required to restrain it. This is a measure of its efficiency. If something deteriorates inside the engine (known as performance deterioration [ 36 ] ) it will be less efficient and this will show when the fuel produces less thrust. If a change is made to an internal part which allows the air/combustion gases to flow more smoothly the engine will be more efficient and use less fuel. A standard definition is used to assess how different things change engine efficiency and also to allow comparisons to be made between different engines. This definition is called specific fuel consumption , or how much fuel is needed to produce one unit of thrust. For example, it will be known for a particular engine design that if some bumps in a bypass duct are smoothed out the air will flow more smoothly giving a pressure loss reduction of x% and y% less fuel will be needed to get the take-off thrust, for example. This understanding comes under the engineering discipline Jet engine performance . How efficiency is affected by forward speed and by supplying energy to aircraft systems is mentioned later.
The efficiency of the engine is controlled primarily by the operating conditions inside the engine which are the pressure produced by the compressor and the temperature of the combustion gases at the first set of rotating turbine blades. The pressure is the highest air pressure in the engine. The turbine rotor temperature is not the highest in the engine but is the highest at which energy transfer takes place ( higher temperatures occur in the combustor). The above pressure and temperature are shown on a Thermodynamic cycle diagram.
The efficiency is further modified by how smoothly the air and the combustion gases flow through the engine, how well the flow is aligned (known as incidence angle) with the moving and stationary passages in the compressors and turbines. [ 37 ] Non-optimum angles, as well as non-optimum passage and blade shapes can cause thickening and separation of Boundary layers and formation of Shock waves . It is important to slow the flow (lower speed means less pressure losses or Pressure drop ) when it travels through ducts connecting the different parts. How well the individual components contribute to turning fuel into thrust is quantified by measures like efficiencies for the compressors, turbines and combustor and pressure losses for the ducts. These are shown as lines on a Thermodynamic cycle diagram.
The engine efficiency, or thermal efficiency , [ 38 ] known as η t h {\displaystyle \eta _{th}} . is dependent on the Thermodynamic cycle parameters, maximum pressure and temperature, and on component efficiencies, η c o m p r e s s o r {\displaystyle \eta _{compressor}} , η c o m b u s t i o n {\displaystyle \eta _{combustion}} and η t u r b i n e {\displaystyle \eta _{turbine}} and duct pressure losses.
The engine needs compressed air for itself just to run successfully. This air comes from its own compressor and is called secondary air. It does not contribute to making thrust so makes the engine less efficient. It is used to preserve the mechanical integrity of the engine, to stop parts overheating and to prevent oil escaping from bearings for example. Only some of this air taken from the compressors returns to the turbine flow to contribute to thrust production. Any reduction in the amount needed improves the engine efficiency. Again, it will be known for a particular engine design that a reduced requirement for cooling flow of x% will reduce the specific fuel consumption by y%. In other words, less fuel will be required to give take-off thrust, for example. The engine is more efficient.
All of the above considerations are basic to the engine running on its own and, at the same time, doing nothing useful, i.e. it is not moving an aircraft or supplying energy for the aircraft's electrical, hydraulic and air systems. In the aircraft the engine gives away some of its thrust-producing potential, or fuel, to power these systems. These requirements, which cause installation losses, [ 39 ] reduce its efficiency. It is using some fuel that does not contribute to the engine's thrust.
Finally, when the aircraft is flying the propelling jet itself contains wasted kinetic energy after it has left the engine. This is quantified by the term propulsive, or Froude, efficiency η p {\displaystyle \eta _{p}} and may be reduced by redesigning the engine to give it bypass flow and a lower speed for the propelling jet, for example as a turboprop or turbofan engine. At the same time forward speed increases the η t h {\displaystyle \eta _{th}} by increasing the Overall pressure ratio .
The overall efficiency of the engine at flight speed is defined as η o = η p η t h {\displaystyle \eta _{o}=\eta _{p}\eta _{th}} . [ 40 ]
The η o {\displaystyle \eta _{o}} at flight speed depends on how well the intake compresses the air before it is handed over to the engine compressors. The intake compression ratio, which can be as high as 32:1 at Mach 3, adds to that of the engine compressor to give the Overall pressure ratio and η t h {\displaystyle \eta _{th}} for the Thermodynamic cycle. How well it does this is defined by its pressure recovery or measure of the losses in the intake. Mach 3 manned flight has provided an interesting illustration of how these losses can increase dramatically in an instant. The North American XB-70 Valkyrie and Lockheed SR-71 Blackbird at Mach 3 each had pressure recoveries of about 0.8, [ 41 ] [ 42 ] due to relatively low losses during the compression process, i.e. through systems of multiple shocks. During an 'unstart' the efficient shock system would be replaced by a very inefficient single shock beyond the inlet and an intake pressure recovery of about 0.3 and a correspondingly low pressure ratio.
The propelling nozzle at speeds above about Mach 2 usually has extra internal thrust losses because the exit area is not big enough as a trade-off with external afterbody drag. [ 43 ]
Although a bypass engine improves propulsive efficiency it incurs losses of its own inside the engine itself. Machinery has to be added to transfer energy from the gas generator to a bypass airflow. The low loss from the propelling nozzle of a turbojet is added to with extra losses due to inefficiencies in the added turbine and fan. [ 44 ] These may be included in a transmission, or transfer, efficiency η T {\displaystyle \eta _{T}} . However, these losses are more than made up [ 45 ] by the improvement in propulsive efficiency. [ 46 ] There are also extra pressure losses in the bypass duct and an extra propelling nozzle.
With the advent of turbofans with their loss-making machinery what goes on inside the engine has been separated by Bennett, [ 47 ] for example, between gas generator and transfer machinery giving η o = η p η t h η T {\displaystyle \eta _{o}=\eta _{p}\eta _{th}\eta _{T}} .
The energy efficiency ( η o {\displaystyle \eta _{o}} ) of jet engines installed in vehicles has two main components:
Even though overall energy efficiency η o {\displaystyle \eta _{o}} is:
for all jet engines the propulsive efficiency is highest as the exhaust jet velocity gets closer to the vehicle speed as this gives the smallest residual kinetic energy. [ a ] For an airbreathing engine an exhaust velocity equal to the vehicle velocity, or a η p {\displaystyle \eta _{p}} equal to one, gives zero thrust with no net momentum change. [ 48 ] The formula for air-breathing engines moving at speed v {\displaystyle v} with an exhaust velocity v e {\displaystyle v_{e}} , and neglecting fuel flow, is: [ 49 ]
And for a rocket: [ 50 ]
In addition to propulsive efficiency, another factor is cycle efficiency ; a jet engine is a form of heat engine. Heat engine efficiency is determined by the ratio of temperatures reached in the engine to that exhausted at the nozzle. This has improved constantly over time as new materials have been introduced to allow higher maximum cycle temperatures. For example, composite materials, combining metals with ceramics, have been developed for HP turbine blades, which run at the maximum cycle temperature. [ 51 ] The efficiency is also limited by the overall pressure ratio that can be achieved. Cycle efficiency is highest in rocket engines (~60+%), as they can achieve extremely high combustion temperatures. Cycle efficiency in turbojet and similar is nearer to 30%, due to much lower peak cycle temperatures.
The combustion efficiency of most aircraft gas turbine engines at sea level takeoff conditions
is almost 100%. It decreases nonlinearly to 98% at altitude cruise conditions. Air-fuel ratio ranges from 50:1 to 130:1. For any type of combustion chamber there is a rich and weak limit to the air-fuel ratio, beyond which the flame is extinguished. The range of air-fuel ratio between the rich and weak limits is reduced with an increase of air velocity. If the
increasing air mass flow reduces the fuel ratio below certain value, flame extinction occurs. [ 52 ]
A closely related (but different) concept to energy efficiency is the rate of consumption of propellant mass. Propellant consumption in jet engines is measured by specific fuel consumption , specific impulse , or effective exhaust velocity . They all measure the same thing. Specific impulse and effective exhaust velocity are strictly proportional, whereas specific fuel consumption is inversely proportional to the others.
For air-breathing engines such as turbojets, energy efficiency and propellant (fuel) efficiency are much the same thing, since the propellant is a fuel and the source of energy. In rocketry, the propellant is also the exhaust, and this means that a high energy propellant gives better propellant efficiency but can in some cases actually give lower energy efficiency.
It can be seen in the table (just below) that the subsonic turbofans such as General Electric's CF6 turbofan use a lot less fuel to generate thrust for a second than did the Concorde 's Rolls-Royce/Snecma Olympus 593 turbojet. However, since energy is force times distance and the distance per second was greater for the Concorde, the actual power generated by the engine for the same amount of fuel was higher for the Concorde at Mach 2 than the CF6. Thus, the Concorde's engines were more efficient in terms of energy per distance traveled.
The thrust-to-weight ratio of jet engines with similar configurations varies with scale, but is mostly a function of engine construction technology. For a given engine, the lighter the engine, the better the thrust-to-weight is, the less fuel is used to compensate for drag due to the lift needed to carry the engine weight, or to accelerate the mass of the engine.
As can be seen in the following table, rocket engines generally achieve much higher thrust-to-weight ratios than duct engines such as turbojet and turbofan engines. This is primarily because rockets almost universally use dense liquid or solid reaction mass which gives a much smaller volume and hence the pressurization system that supplies the nozzle is much smaller and lighter for the same performance. Duct engines have to deal with air which is two to three orders of magnitude less dense and this gives pressures over much larger areas, which in turn results in more engineering materials being needed to hold the engine together and for the air compressor.
Propeller engines handle larger air mass flows, and give them smaller acceleration, than jet engines. Since the increase in air speed is small, at high flight speeds the thrust available to propeller-driven aeroplanes is small. However, at low speeds, these engines benefit from relatively high propulsive efficiency .
On the other hand, turbojets accelerate a much smaller mass flow of intake air and burned fuel, but they then reject it at very high speed. When a de Laval nozzle is used to accelerate a hot engine exhaust, the outlet velocity may be locally supersonic . Turbojets are particularly suitable for aircraft travelling at very high speeds.
Turbofans have a mixed exhaust consisting of the bypass air and the hot combustion product gas from the core engine. The amount of air that bypasses the core engine compared to the amount flowing into the engine determines what is called a turbofan's bypass ratio (BPR).
While a turbojet engine uses all of the engine's output to produce thrust in the form of a hot high-velocity exhaust gas jet, a turbofan's cool low-velocity bypass air yields between 30% and 70% of the total thrust produced by a turbofan system. [ 80 ]
The net thrust ( F N ) generated by a turbofan can also be expanded as: [ 81 ]
where:
Rocket engines have extremely high exhaust velocity and thus are best suited for high speeds ( hypersonic ) and great altitudes. At any given throttle, the thrust and efficiency of a rocket motor improves slightly with increasing altitude (because the back-pressure falls thus increasing net thrust at the nozzle exit plane), whereas with a turbojet (or turbofan) the falling density of the air entering the intake (and the hot gases leaving the nozzle) causes the net thrust to decrease with increasing altitude. Rocket engines are more efficient than even scramjets above roughly Mach 15. [ 82 ]
With the exception of scramjets , jet engines, deprived of their inlet systems can only accept air at around half the speed of sound. The inlet system's job for transonic and supersonic aircraft is to slow the air and perform some of the compression.
The limit on maximum altitude for engines is set by flammability – at very high altitudes the air becomes too thin to burn, or after compression, too hot. For turbojet engines altitudes of about 40 km appear to be possible, whereas for ramjet engines 55 km may be achievable. Scramjets may theoretically manage 75 km. [ 83 ] Rocket engines of course have no upper limit.
At more modest altitudes, flying faster compresses the air at the front of the engine , and this greatly heats the air. The upper limit is usually thought to be about Mach 5–8, as above about Mach 5.5, the atmospheric nitrogen tends to react due to the high temperatures at the inlet and this consumes significant energy. The exception to this is scramjets which may be able to achieve about Mach 15 or more, [ citation needed ] as they avoid slowing the air, and rockets again have no particular speed limit.
The noise emitted by a jet engine has many sources. These include, in the case of gas turbine engines, the fan, compressor, combustor, turbine and propelling jet/s. [ 84 ]
The propelling jet produces jet noise which is caused by the violent mixing action of the high speed jet with the surrounding air. In the subsonic case the noise is produced by eddies and in the supersonic case by Mach waves . [ 85 ] The sound power radiated from a jet varies with the jet velocity raised to the eighth power for velocities up to 600 m/s (2,000 ft/s) and varies with the velocity cubed above 600 m/s (2,000 ft/s). [ 86 ] Thus, the lower speed exhaust jets emitted from engines such as high bypass turbofans are the quietest, whereas the fastest jets, such as rockets, turbojets, and ramjets, are the loudest. For commercial jet aircraft the jet noise has reduced from the turbojet through bypass engines to turbofans as a result of a progressive reduction in propelling jet velocities. For example, the JT8D, a bypass engine, has a jet velocity of 400 m/s (1,450 ft/s) whereas the JT9D, a turbofan, has jet velocities of 300 m/s (885 ft/s) (cold) and 400 m/s (1,190 ft/s)(hot). [ 87 ]
The advent of the turbofan replaced the very distinctive jet noise with another sound known as "buzz saw" noise. The origin is the shockwaves originating at the supersonic fan blade tip at takeoff thrust. [ 88 ]
Adequate heat transfer away from the working parts of the jet engine is critical to maintaining strength of engine materials and ensuring long life for the engine.
After 2016, research is ongoing in the development of transpiration cooling techniques to jet engine components. [ 89 ]
In a jet engine, each major rotating section usually has a separate gauge devoted to monitoring its speed of rotation.
Depending on the make and model, a jet engine may have an N 1 gauge that monitors the low-pressure compressor section and/or fan speed in turbofan engines. The gas generator section may be monitored by an N 2 gauge, while triple spool engines may have an N 3 gauge as well. Each engine section rotates at many thousands RPM. Their gauges therefore are calibrated in percent of a nominal speed rather than actual RPM, for ease of display and interpretation. [ 90 ] | https://en.wikipedia.org/wiki/Jet_engine |
A jet fire is a high temperature flame of burning fuel released under pressure in a particular orientation. The material burned is a continuous stream of flammable gas, liquid or a two-phase mixture. A jet fire is a significant hazard in process and storage plants which handle or keep flammable fluids under pressure. The heat flux of the jet flame can cause rapid mechanical failure thereby compromising structural integrity and leading to incident escalation.
The Piper Alpha disaster in 1988 demonstrated how the accidental release of hydrocarbon can lead to the catastrophic failure of an installation with the rupture of major pipeline risers. [ 1 ] Jet fires impinged on vessels, pipework and firewalls. Under these conditions the fireproofing material was compromised within a few minutes rather than one to two hours, which had been specified. Even without direct impingement, the high thermal radiation emitted by jet flames also affected plant and would have been fatal to personnel. [ 2 ]
A jet fire, also known as a spray fire if the fuel is a liquid or liquefied gas, is a turbulent diffusion flame of flammable material. [ 3 ] The characteristics of a jet fire depend on a number of factors. These include: fuel composition; release conditions; release rate; release geometry; direction; and ambient wind conditions.
For full details of the mechanism and structure of jet fires see High Pressure Jet .
Some characteristics of specific jet fires are: [ 3 ]
Process plant is generally protected by a pressure relief system. However, local heating of a pressure vessel by a jet fire may compromise the integrity of the vessel before the pressure relief device operates. The measures taken for protection against jet fires are as follows: [ 2 ]
Water deluge can reduce the heat loading of plant so that its temperature is maintained below that at which failure occurs, or that the temperature rise is sufficiently reduced such that shutdown and depressurization can take place. [ 1 ]
Older plants may have been sized on an earlier version of the American Petroleum Institute 's Pressure-Relieving and Depressuring Systems standard, [ 2 ] which did not include consideration of jet fires.
The international standard publication ISO 22899 ( Determination of the Resistance to Jet Fires of Passive Fire Protection Materials ) sets requirements for the specification of passive fire protection against jet fires. | https://en.wikipedia.org/wiki/Jet_fire |
Jet force is the exhaust from some machine, especially aircraft, propelling the object itself in the opposite direction as per Newton's third law . An understanding of jet force is intrinsic to the launching of drones, satellites, rockets, airplanes and other airborne machines.
Jet force begins with some propulsion system; in the case of a rocket, this is usually some system that kicks out combustible gases from the bottom. This repulsion system pushes out these gas molecules in the direction opposite the intended motion so rapidly that the opposite force, acting 180° away from the direction the gas molecules are moving, (as such, in the intended direction of movement) pushes the rocket up. A common wrong assumption is that the rocket elevates by pushing off the ground. If this were the case, the rocket would be unable to continue moving upwards after the aircraft is no longer close to the ground. Rather, the opposite force by the expelled gases is the reason for movement.
The jet force can be divided into components. The "forward" component of this force is generally referred to as thrust . [ 1 ] The upward component of jet force is referred to as lift . [ 2 ] There are also two other forces that impact motion of aircraft. Drag , which is also referred to as air resistance, is the force that opposes motion. As such, it acts against both components of the jet force (both the thrust and the lift). The fourth and final force is the weight itself, which acts directly downward.
To analyze thrust, we take a mathematical perspective.
Because θ ranges from 0° to 90° and the cosine of any angle in this range is 0 ≤ cos θ≤ 1, the thrust will always be either less than or equal to the jet force- as expected, as the thrust is a component of the jet force.
Similar to our analysis of thrust, we begin with a mathematical look:
Similar to cosine, the sine of an angle ranging from 0° to 90° will always between at least zero and at most one. As such, the lift will also be less than the jet force. Of jet force, lift and thrust, we can find any one of these if the other two are given using the distance formula. In this case, that would be: Jet Force = Thrust 2 + Lift 2 {\displaystyle {\text{Jet Force}}={\sqrt {{\text{Thrust}}^{2}+{\text{Lift}}^{2}}}}
As such, jet force, thrust and lift are inherently linked.
Drag, or air resistance, is a force that opposes motion. Since the thrust is a force that provides "forward motion" and, lift one that produces "upward motion", the drag opposes both of these forces. Air resistance is friction between the air itself and the moving object (in this case the aircraft). The calculation of air resistance is far more complicated than that of thrust and lift- it has to do with the material of the aircraft, the speed of the aircraft and other variable factors. However, rockets and airplanes are built with materials and in shapes that minimize drag force, maximizing the force that moves the aircraft upward/forward. [ 3 ]
Weight is the downward force that the lift must overcome to produce upward movement. On earth, weight is fairly easy to calculate: Weight = m g {\displaystyle {\text{Weight}}=mg}
In this equation, m represents the mass of the object and g is the acceleration that is produced by gravity. On earth, this value is approximately 9.8 m/s squared. When the force for lift is greater than the force of weight, the aircraft accelerates upwards.
To calculate the speed of the vessel due to the jet force itself, analysis of momentum is necessary. Conservation of momentum [ 4 ] states the following: m 1 v 1 + m 2 v 2 = m 1 v 1 f + m 2 v 2 f {\displaystyle m_{1}v_{1}+m_{2}v_{2}=m_{1}v_{1f}+m_{2}v_{2f}}
In this situation, m 1 represents the mass of the gas in the propulsion system, v 1 represents the initial speed of this gas, m 2 represents the mass of the rocket and v 2 represents the initial velocity of the rocket. On the other end of the equation, v 1f represents the final velocity of the gas and v 2f represents the final velocity of the rocket. Initially, both the gas in the propulsion system and the rocket are stationary, leading to v 1 and v 2 equaling 0. As such, the equation can be simplified to the following: 0 = m 1 v 1 f + m 2 v 2 f {\displaystyle 0=m_{1}v_{1f}+m_{2}v_{2f}}
After some more simple algebra, we can calculate that v 2 (the velocity of the rocket) is the following: v 2 f = − m 1 v 1 m 2 {\displaystyle v_{2f}=-{\frac {m_{1}v_{1}}{m_{2}}}}
This gives us the velocity of the aircraft right after it takes off. Because we know all forces acting on it from this point on, we can calculate net acceleration using Newton's second law . [ 5 ] Given the velocity that the aircraft takes off with and the acceleration at any point, the velocity can also be calculated at any given point. [ 6 ] | https://en.wikipedia.org/wiki/Jet_force |
Jet fuel or aviation turbine fuel ( ATF , also abbreviated avtur ) is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines . It is colorless to straw-colored in appearance. The most commonly used fuels for commercial aviation are Jet A and Jet A-1, which are produced to a standardized international specification. The only other jet fuel commonly used in civilian turbine-engine powered aviation is Jet B, which is used for its enhanced cold-weather performance.
Jet fuel is a mixture of a variety of hydrocarbons . Because the exact composition of jet fuel varies widely based on petroleum source, it is impossible to define jet fuel as a ratio of specific hydrocarbons. Jet fuel is therefore defined as a performance specification rather than a chemical compound. [ 1 ] Furthermore, the range of molecular mass between hydrocarbons (or different carbon numbers) is defined by the requirements for the product, such as the freezing point or smoke point. Kerosene -type jet fuel (including Jet A and Jet A-1, JP-5, and JP-8) has a carbon number distribution between about 8 and 16 (carbon atoms per molecule); wide-cut or naphtha -type jet fuel (including Jet B and JP-4), between about 5 and 15. [ 2 ] [ 3 ]
Fuel for piston-engine powered aircraft (usually a high- octane gasoline known as avgas ) has a high volatility to improve its carburetion characteristics and high autoignition temperature to prevent preignition in high compression aircraft engines. Turbine engines (as with diesel engines ) can operate with a wide range of fuels because fuel is injected into the hot combustion chamber. Jet and gas turbine ( turboprop , helicopter ) aircraft engines typically use lower cost fuels with higher flash points , which are less flammable and therefore safer to transport and handle.
The first axial compressor jet engine in widespread production and combat service, the Junkers Jumo 004 used on the Messerschmitt Me 262A fighter and the Arado Ar 234B jet recon-bomber, burned either a special synthetic "J2" fuel or diesel fuel. Gasoline was a third option but unattractive due to high fuel consumption. [ 4 ] Other fuels used were kerosene or kerosene and gasoline mixtures.
A pressure to move from Jet fuel to sustainable aviation fuel , aka Aviation biofuel , has existed since before the 2016 Paris Agreement . [ 5 ] [ 6 ]
Most jet fuels in use since the end of World War II are kerosene-based. Both British and American standards for jet fuels were first established at the end of World War II. British standards derived from standards for kerosene use for lamps—known as paraffin in the UK—whereas American standards derived from aviation gasoline practices. Over the subsequent years, details of specifications were adjusted, such as minimum freezing point, to balance performance requirements and availability of fuels. Very low temperature freezing points reduce the availability of fuel. Higher flash point products required for use on aircraft carriers are more expensive to produce. [ 3 ] In the United States, ASTM International produces standards for civilian fuel types, and the U.S. Department of Defense produces standards for military use. The British Ministry of Defence establishes standards for both civil and military jet fuels. [ 3 ] For reasons of inter-operational ability, British and United States military standards are harmonized to a degree. In Russia and the CIS members, grades of jet fuels are covered by the State Standard ( GOST ) number, or a Technical Condition number, with the principal grade available being TS-1.
Jet A specification fuel has been used in the United States since the 1950s and is usually not available outside the United States [ 7 ] and a few Canadian airports such as Toronto , Montreal , and Vancouver , [ 8 ] whereas Jet A-1 is the standard specification fuel used in most of the rest of the world, [ a ] the main exceptions being Russia and the CIS members, where TS-1 fuel type is the most common standard. Both Jet A and Jet A-1 have a flash point higher than 38 °C (100 °F), with an autoignition temperature of 210 °C (410 °F). [ 11 ]
The differences between Jet A and Jet A-1 are twofold. The primary difference is the lower freezing point of Jet A-1 fuel: [ 7 ]
The other difference is the mandatory addition of an antistatic additive to Jet A-1 fuel.
Jet A and Jet A-1 fuel trucks and storage tanks, as well as plumbing that carries them, are all marked "Jet A" or "Jet A-1" in white italicized text within a black rectangle background,
Jet A-1 fuel must meet:
Jet A fuel must reach ASTM specification D1655 (Jet A). [ 12 ]
Jet B is a naphtha-kerosene fuel that is used for its enhanced cold-weather performance. However, Jet B's lighter composition makes it more dangerous to handle. [ 12 ] For this reason, it is rarely used, except in very cold climates. A blend of approximately 30% kerosene and 70% gasoline, it is known as wide-cut fuel. It has a very low freezing point of −60 °C (−76 °F), and a low flash point as well. It is primarily used in northern Canada and Alaska , where the extreme cold makes its low freezing point necessary, and which helps mitigate the danger of its lower flash point.
The GOST standard 10227 specifies civilian fuels, among which TS-1, T-1, T-1S, T2 and RT. [ 18 ] Military fuels such as T-1pp, [ 19 ] T-8V (aka T-8B) and T-6 are specified by GOST 12308. [ 18 ] Icing inhibitors are specified by GOST 8313. [ 18 ] Some researchers refer to T-6 as "ram rocket fuel"; [ 20 ] others have patented a method used to produce T-1pp from a mixture of T-6 and RT, [ 19 ] the latter of which has been characterized as "unified Russian fuel for sub- and supersonic aircraft". [ 21 ]
TS-1 is a jet fuel made to Russian standard GOST 10227 for enhanced cold-weather performance. It has somewhat higher volatility than Jet A-1 (flash point is 28 °C (82 °F) minimum). It has a very low freezing point, below −50 °C (−58 °F). [ 22 ]
The DEF STAN 91-091 (UK) and ASTM D1655 (international) specifications allow for certain additives to be added to jet fuel, including: [ 23 ] [ 24 ]
As the aviation industry's jet kerosene demands have increased to more than 5% of all refined products derived from crude,
it has been necessary for the refiner to optimize the yield of jet kerosene, a high-value product, by varying process techniques.
New processes have allowed flexibility in the choice of crudes, the use of coal tar sands as a source of molecules and the
manufacture of synthetic blend stocks. Due to the number and severity of the processes used, it is often necessary and
sometimes mandatory to use additives. These additives may, for example, prevent the formation of harmful chemical species
or improve a property of a fuel to prevent further engine wear.
It is very important that jet fuel be free from water contamination . During flight, the temperature of the fuel in the tanks decreases, due to the low temperatures in the upper atmosphere . This causes precipitation of the dissolved water from the fuel. The separated water then drops to the bottom of the tank, because it is denser than the fuel. Since the water is no longer in solution, it can form droplets which can supercool to below 0 °C (32 °F). If these supercooled droplets collide with a surface they can freeze and may result in blocked fuel inlet pipes. [ 27 ] This was the cause of the British Airways Flight 38 accident. Removing all water from fuel is impractical; therefore, fuel heaters are usually used on commercial aircraft to prevent water in fuel from freezing.
There are several methods for detecting water in jet fuel. A visual check may detect high concentrations of suspended water, as this will cause the fuel to become hazy in appearance. An industry standard chemical test for the detection of free water in jet fuel uses a water-sensitive filter pad that turns green if the fuel exceeds the specification limit of 30 ppm (parts per million) free water. [ 28 ] A critical test to rate the ability of jet fuel to release emulsified water when passed through coalescing filters is ASTM standard D3948 Standard Test Method for Determining Water Separation Characteristics of Aviation Turbine Fuels by Portable Separometer.
Military organizations around the world use a different classification system of JP (for "Jet Propellant") numbers. Some are almost identical to their civilian counterparts and differ only by the amounts of a few additives; Jet A-1 is similar to JP-8 , Jet B is similar to JP-4 . [ 29 ] Other military fuels are highly specialized products and are developed for very specific applications.
Jet fuel is very similar to diesel fuel , and in some cases, may be used in diesel engines . The possibility of environmental legislation banning the use of leaded avgas (fuel in spark-ignited internal combustion engine, which usually contains tetraethyllead (TEL), a toxic substance added to prevent engine knocking ), and the lack of a replacement fuel with similar performance, has left aircraft designers and pilot's organizations searching for alternative engines for use in small aircraft. [ 42 ] As a result, a few aircraft engine manufacturers, most notably Thielert and Austro Engine , have begun offering aircraft diesel engines which run on jet fuel which may simplify airport logistics by reducing the number of fuel types required. Jet fuel is available in most places in the world, whereas avgas is only widely available in a few countries which have a large number of general aviation aircraft. A diesel engine may be more fuel-efficient than an avgas engine. However, very few diesel aircraft engines have been certified by aviation authorities. Diesel aircraft engines are uncommon today, even though opposed-piston aviation diesel powerplants such as the Junkers Jumo 205 family had been used during the Second World War.
Jet fuel is often used in diesel-powered ground-support vehicles at airports. However, jet fuel tends to have poor lubricating ability in comparison to diesel, which increases wear in fuel injection equipment. [ citation needed ] An additive may be required to restore its lubricity . Jet fuel is more expensive than diesel fuel but the logistical advantages of using one fuel can offset the extra expense of its use in certain circumstances.
Jet fuel contains more sulfur, up to 1,000 ppm, which therefore means it has better lubricity and does not currently require a lubricity additive as all pipeline diesel fuels require. [ citation needed ] The introduction of Ultra Low Sulfur Diesel or ULSD brought with it the need for lubricity modifiers. Pipeline diesels before ULSD were able to contain up to 500 ppm of sulfur and were called Low Sulfur Diesel or LSD. In the United States LSD is now only available to the off-road construction, locomotive and marine markets. As more EPA regulations are introduced, more refineries are hydrotreating their jet fuel production, thus limiting the lubricating abilities of jet fuel, as determined by ASTM Standard D445.
JP-8 , which is similar to Jet A-1, is used in NATO diesel vehicles as part of the single-fuel policy. [ 43 ]
Fischer–Tropsch (FT) Synthesized Paraffinic Kerosene (SPK) synthetic fuels are certified for use in United States and international aviation fleets at up to 50% in a blend with conventional jet fuel. [ 44 ] As of the end of 2017, four other pathways to SPK are certified, with their designations and maximum blend percentage in brackets: Hydroprocessed Esters and Fatty Acids (HEFA SPK, 50%); synthesized iso-paraffins from hydroprocessed fermented sugars (SIP, 10%); synthesized paraffinic kerosene plus aromatics (SPK/A, 50%); alcohol-to-jet SPK (ATJ-SPK, 30%). Both FT and HEFA based SPKs blended with JP-8 are specified in MIL-DTL-83133H.
Some synthetic jet fuels show a reduction in pollutants such as SOx, NOx, particulate matter, and sometimes carbon emissions. [ 45 ] [ 46 ] [ 47 ] [ 48 ] [ 49 ] It is envisaged that usage of synthetic jet fuels will increase air quality around airports which will be particularly advantageous at inner city airports. [ 50 ]
Qatar Airways became the first airline to operate a commercial flight on a 50:50 blend of synthetic Gas to Liquid (GTL) jet fuel and conventional jet fuel. The natural gas derived synthetic kerosene for the six-hour flight from London to Doha came from Shell's GTL plant in Bintulu , Malaysia . [ 51 ] The world's first passenger aircraft flight to use only synthetic jet fuel was from Lanseria International Airport to Cape Town International Airport on September 22, 2010. The fuel was developed by Sasol . [ 52 ]
Chemist Heather Willauer is leading a team of researchers at the U.S. Naval Research Laboratory who are developing a process to make jet fuel from seawater. The technology requires an input of electrical energy to separate Oxygen (O 2 ) and Hydrogen (H 2 ) gas from seawater using an iron-based catalyst, followed by an oligomerization step wherein carbon monoxide (CO) and hydrogen are recombined into long-chain hydrocarbons, using zeolite as the catalyst. The technology is expected to be deployed in the 2020s by U.S. Navy warships, especially nuclear-powered aircraft carriers. [ 53 ] [ 54 ] [ 55 ] [ 56 ] [ 57 ] [ 58 ]
On February 8, 2021, the world's first scheduled passenger flight flew with some synthetic kerosene from a non-fossil fuel source. 500 liters of synthetic kerosene was mixed with regular jet fuel. Synthetic kerosene was produced by Shell and the flight was operated by KLM. [ 59 ]
On August 8, 2007, Air Force Secretary Michael Wynne certified the B-52H as fully approved to use the FT blend, marking the formal conclusion of the test program.
This program is part of the Department of Defense Assured Fuel Initiative, an effort to develop secure domestic sources for the military energy needs. The Pentagon hopes to reduce its use of crude oil from foreign producers and obtain about half of its aviation fuel from alternative sources by 2016. With the B-52 now approved to use the FT blend, the USAF will use the test protocols developed during the program to certify the Boeing C-17 Globemaster III and then the Rockwell B-1B Lancer to use the fuel. To test these two aircraft, the USAF has ordered 281,000 US gal (1,060,000 L) of FT fuel. The USAF intends to test and certify every airframe in its inventory to use the fuel by 2011. They will also supply over 9,000 US gal (34,000 L; 7,500 imp gal) to NASA for testing in various aircraft and engines. [ needs update ]
The USAF has certified the B-1B, B-52H, C-17, Lockheed Martin C-130J Super Hercules , McDonnell Douglas F-4 Phantom (as QF-4 target drones ), McDonnell Douglas F-15 Eagle , Lockheed Martin F-22 Raptor , and Northrop T-38 Talon to use the synthetic fuel blend. [ 60 ]
The U.S. Air Force's C-17 Globemaster III, F-16 and F-15 are certified for use of hydrotreated renewable jet fuels. [ 61 ] [ 62 ] The USAF plans to certify over 40 models for fuels derived from waste oils and plants by 2013. [ 62 ] The U.S. Army is considered one of the few customers of biofuels large enough to potentially bring biofuels up to the volume production needed to reduce costs. [ 62 ] The U.S. Navy has also flown a Boeing F/A-18E/F Super Hornet dubbed the "Green Hornet" at 1.7 times the speed of sound using a biofuel blend. [ 62 ] The Defense Advanced Research Projects Agency (DARPA) funded a $6.7 million project with Honeywell UOP to develop technologies to create jet fuels from biofeedstocks for use by the United States and NATO militaries. [ 63 ]
In April 2011, four USAF F-15E Strike Eagles flew over the Philadelphia Phillies opening ceremony using a blend of traditional jet fuel and synthetic biofuels. This flyover made history as it was the first flyover to use biofuels in the Department of Defense . [ 64 ]
The air transport industry is responsible for 2–3 percent of man-made carbon dioxide emitted. [ 65 ] Boeing estimates that biofuels could reduce flight-related greenhouse-gas emissions by 60 to 80 percent. One possible solution which has received more media coverage than others would be blending synthetic fuel derived from algae with existing jet fuel: [ 66 ]
Solazyme produced the world's first 100 percent algae-derived jet fuel, Solajet, for both commercial and military applications. [ 74 ]
Oil prices increased about fivefold from 2003 to 2008, raising fears that world petroleum production is becoming unable to keep up with demand . The fact that there are few alternatives to petroleum for aviation fuel adds urgency to the search for alternatives . Twenty-five airlines were bankrupted or stopped operations in the first six months of 2008, largely due to fuel costs. [ 75 ]
In 2015 ASTM approved a modification to Specification D1655 Standard Specification for Aviation Turbine Fuels to permit up to 50 ppm (50 mg/kg) of FAME ( fatty acid methyl ester ) in jet fuel to allow higher cross-contamination from biofuel production. [ 76 ]
Worldwide demand of jet fuel has been steadily increasing since 1980. Consumption more than tripled in 30 years from 1,837,000 barrels/day in 1980, to 5,220,000 in 2010. [ 77 ] Around 30% of the worldwide consumption of jet fuel is in the US (1,398,130 barrels/day in 2012).
Article 24 of the Chicago Convention on International Civil Aviation of 7 December 1944 stipulates that when flying from one contracting state to another, the fuel that is already on board aircraft may not be taxed by the state where the aircraft lands, nor by a state through whose airspace the aircraft has flown. This is to prevent double taxation. It is sometimes suggested that the Chicago Convention precludes the taxation of aviation fuel. However, this is not correct. The Chicago Convention does not preclude a fuel tax on domestic flights or on refuelling before international flights. [ 78 ] : 22
Article 15 of the Chicago Convention is also sometimes said to ban fuel taxes. Article 15 states: "No fees, dues or other charges shall be imposed by any contracting State in respect solely of the right of transit over or entry into or exit from its territory of any aircraft of a contracting State or persons or property thereon." However, ICAO distinguishes between charges and taxes, and Article 15 does not prohibit the levying of taxes without a service
provided. [ 78 ] : 23
In the European Union, commercial aviation fuel is exempt from taxation , according to the 2003 Energy Taxation Directive . [ 79 ] EU member states may tax jet fuel via bilateral agreements, however no such agreements exist. [ 78 ]
In the United States, most states tax jet fuel .
General health hazards associated with exposure to jet fuel vary according to its components, exposure duration (acute vs. long-term), route of administration (dermal vs. respiratory vs. oral), and exposure phase (vapor vs. aerosol vs. raw fuel). [ 80 ] [ 81 ] Kerosene-based hydrocarbon fuels are complex mixtures which may contain up to 260+ aliphatic and aromatic hydrocarbon compounds including toxicants such as benzene, n-hexane, toluene, xylenes, trimethylpentane, methoxyethanol, naphthalenes. [ 81 ] While time-weighted average hydrocarbon fuel exposures can often be below recommended exposure limits, peak exposure can occur, and the health impact of occupational exposures is not fully understood. Evidence of the health effects of jet fuels comes from reports on both temporary or persisting biological from acute, subchronic, or chronic exposure of humans or animals to kerosene-based hydrocarbon fuels, or the constituent chemicals of these fuels, or to fuel combustion products. The effects studied include: cancer , skin conditions , respiratory disorders , [ 82 ] immune and hematological disorders , [ 83 ] neurological effects , [ 84 ] visual and hearing disorders , [ 85 ] [ 86 ] renal and hepatic diseases , cardiovascular conditions, gastrointestinal disorders, genotoxic and metabolic effects. [ 81 ] [ 87 ] | https://en.wikipedia.org/wiki/Jet_fuel |
In mathematics , a jet group is a generalization of the general linear group which applies to Taylor polynomials instead of vectors at a point. A jet group is a group of jets that describes how a Taylor polynomial transforms under changes of coordinate systems (or, equivalently, diffeomorphisms ).
The k -th order jet group G n k consists of jets of smooth diffeomorphisms φ: R n → R n such that φ(0)=0. [ 1 ]
The following is a more precise definition of the jet group.
Let k ≥ 2. The differential of a function f: R k → R can be interpreted as a section of the cotangent bundle of R K given by df: R k → T* R k . Similarly, derivatives of order up to m are sections of the jet bundle J m ( R k ) = R k × W , where
Here R * is the dual vector space to R , and S i denotes the i -th symmetric power . A smooth function f: R k → R has a prolongation j m f : R k → J m ( R k ) defined at each point p ∈ R k by placing the i -th partials of f at p in the S i (( R *) k ) component of W .
Consider a point p = ( x , x ′ ) ∈ J m ( R n ) {\displaystyle p=(x,x')\in J^{m}(\mathbf {R} ^{n})} . There is a unique polynomial f p in k variables and of order m such that p is in the image of j m f p . That is, j k ( f p ) ( x ) = x ′ {\displaystyle j^{k}(f_{p})(x)=x'} . The differential data x′ may be transferred to lie over another point y ∈ R n as j m f p (y) , the partials of f p over y .
Provide J m ( R n ) with a group structure by taking
With this group structure, J m ( R n ) is a Carnot group of class m + 1.
Because of the properties of jets under function composition , G n k is a Lie group . The jet group is a semidirect product of the general linear group and a connected, simply connected nilpotent Lie group . It is also in fact an algebraic group , since the composition involves only polynomial operations.
This algebra -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Jet_group |
In aeroacoustics , jet noise is the field that focuses on the noise generation caused by high-velocity jets and the turbulent eddies generated by shearing flow. Such noise is known as broadband noise and extends well beyond the range of human hearing (100 kHz and higher). Jet noise is also responsible for some of the loudest sounds ever produced by mankind.
The primary sources of jet noise for a high-speed air jet (meaning when the exhaust velocity exceeds about 100 m/s; 360 km/h; 225 mph) are "jet mixing noise" and, for supersonic flow , shock associated noise. Acoustic sources within the "jet pipe" also contribute to the noise, mainly at lower speeds, which include combustion noise, and sounds produced by interactions of a turbulent stream with fans, compressors, and turbine systems. [ 1 ]
The jet mixing sound is created by the turbulent mixing of a jet with the ambient fluid, in most cases, air. The mixing initially occurs in an annular shear layer, which grows with the length of the nozzle. The mixing region generally fills the entire jet at four or five diameters from the nozzle. The high-frequency components of the sound are mainly stationed close to the nozzle, where the dimensions of the turbulence eddies are small. Further down the jet, where the eddy size is similar to the jet diameter, is where lower frequency begins.
In supersonic or choked jets there are cells through which the flow continuously expands and contracts. Several of these "shock cells" can be seen extending up to ten jet diameters from the nozzle and are responsible for two additional components of jet noise, screech tones, and broadband shock associated noises. Screech is produced by a feedback mechanism in which a disturbance convecting in the shear layer generates sound as it traverses the standing system of shock waves in the jet. [ 2 ] Even though screech is a side effect of the jet's flight, it can be suppressed by an appropriate design for a nozzle.
Aircraft noise is also sometimes called jet noise when emanating from jet aircraft , regardless of the mechanism of noise production.
Works cited
This fluid dynamics –related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Jet_noise |
A Jewell water filter was a system of sand filters for filtering and treating water for drinking purposes that made use of gravity to allow water to percolate through a column of sand inside cylindrical cisterns that was widely used in the early twentieth century. They are named after Omar Hestrian Jewell (1 July 1842 - 19 June 1931) established Jewell Pure Water Company in Chicago in 1890 and managed later by two of his sons. Jewell water filters were used in many city water supply systems across the world and modified versions continue to be in use.
Slow sand filters were introduced at a point when the nature of disease causing organisms in typhoid and cholera had been established. Omar Jewell was a mechanical engineer who designed farm equipment and he took an interest in solving some of the problems involved in the filtration of water and established the O.H.Jewell Filter Company and was financed by Chicago-based waterwork dealers James B. Clow and Sons . Omar's son William H. Jewell graduated in 1887 from the College of Pharmacy, University of Illinois and served as a chemist in the company. Another son, Ira worked for a while with the company [ 1 ] but sold his stock in 1900 to start a breakaway company I.H. Jewell Filter Company . [ 2 ]
The first Jewell filters were built for use at Rock Island, Illinois in 1891. Jewell filters evolved over time to substitute open sand bed filters which had problems in the United States: freezing in winter and algal growth in summer introducing an odour to the water. Over time Omar and his sons owned several patents in water filtration, nearly 50 patents between 1888 and 1900, including novel systems for combining filtering and chlorination. [ 1 ] [ 3 ] By 1896 nearly 21 plants in the United States of America used Jewell filters. In 1898 the O.H.Jewell Filter Company settled a patent infringement claim over a coagulation process patented by Isaiah Smith Hyatt, brother of John Wesley Hyatt , in 1884 and owned by the New York Filter Manufacturing Company. Other filter companies came up during the period and there were numerous patent litigations and company mergers with Jewell merging with the New York Filter Manufacturing Company in 1900 [ 4 ] to become the single major New York Continental Jewell Filtration Company. The resulting company owned the licenses to most of the valuable patents of the day and by 1909 they had nearly 360 plants in operation. [ 5 ] Several were built in far away places like India with the largest being in Kolar at Bethamangala with a capacity of 2,000,000 gallons per day. [ 6 ] The one in Warsaw was the largest in Europe in its time. [ 1 ]
An outbreak of typhoid during the 1890s in the city of Pittsburgh led to calls for improved sanitation and improvements in the quality of drinking water supply . Pittsburgh Filtration Commission was established in June 1896 and it recommended in 1899 a slow-sand filtration system. Once this became operational, the cases of typhoid were greatly reduced. [ 7 ] The Filtration commission wrote to several companies but only two agreed to enter the tests. These were the Cumberland manufacturing company and the Morison-Jewell Filtration Company and the committee experimented with a Warren filter and a Jewell filter. [ 8 ] [ 9 ] [ 10 ] Jewell filters underwent further bacteriological tests in Alexandria and Berlin and their approval led to their wider adoption in numerous town water supplies in the early 1900s. [ 6 ] The British troops at Alexandria brought down typhoid deaths to zero by 1905 with water treatments that included the use of Jewell filters. [ 11 ] Jewell filters became commonplace in British Indian military towns in the plains after around 1910 and their construction had been standardized in engineering manuals. [ 12 ] [ 13 ]
Jewell filters, unlike their predecessors, open sand filters, were housed indoors and included mechanical action to turn and wash the sand with their key advantages being their ability to work in winter and reduce bacterial counts. The water from a river or lake is first passed through sedimentation beds where a coagulant such as alum is added. The water then goes into the sand bed within cylinders of the Jewell filters and the coagulant forms a film on top of it. The sand beds are cleaned by stirring them with rotary arms and washing with water pumped at pressure from below. The Warren filter also had a similar system for washing sand. The design to carry away the wash effluent however differed between the Warren and Jewell filters. [ 10 ] The system also included automatic control the flow of water inflow and devices to control the addition of chemicals such as lime and iron. [ 14 ] The company later produced variations that used water under pressure than to merely rely on gravity. [ 15 ] | https://en.wikipedia.org/wiki/Jewell_water_filter |
The Jeyranbatan Ultrafiltration Water Treatment Plants Complex is a water filtration plant in Baku , Azerbaijan . The plant, designed to supply Baku and the Absheron Peninsula with drinking water, was put into operation on 28 October 2015. The capacity of the ultrafiltration (UF) plant is 6.6 cubic meters of water per second (570,000 cubic meters per day). [ 1 ] [ 2 ] The plant complex was chosen as one of the most important water projects in the world at the Global Water Summit in Abu Dhabi in 2016. Companies from the United States, Germany, Switzerland, Spain, Italy, Turkey and the Republic of Korea as well as up to thirty local contractor organizations were involved in the construction of the complex. [ 3 ] [ failed verification ]
The UF treatment plant processes water which is naturally purified in the Jeyranbatan reservoir , which has a capacity of 186 million cubic meters. The raw water is first treated in the coarse screen building by using 3000- micron automatic self-cleaning filters. It then passes through 200-micron filters followed by 0.02-micron filter modules. This process is performed in a mechanically closed environment, without using chemical treatment. As such, the natural mineral content of the water is fully preserved. Water produced in the plant meets the standards set by the World Health Organization and other international organizations. [ citation needed ]
Some quality indicators of water processed in the filters (chlorine residue, cloudiness , pH , TOC) are controlled digitally. Other parameters of raw and treated water are studied in the laboratory of the complex. The volume and water pressure, each stage of processing, and the storage and transportation processes are fully automated. All technological processes are managed in the SCADA control center. [ 4 ]
Processed water is collected in the treated water tank, which has a capacity of 10,000 cubic meters. It is then pumped to the Absheron reservoir , which is located at 118 meters above sea level, and water is distributed to the networks by gravity. [ citation needed ]
The Jeyranbatan-Zira transmission main (with a total length of 83.5 kilometers) is served by the Saray, Balakhani, Ramana, Gala, and Zira reservoirs (with a total capacity of 90,000 cubic meters) which are located along its route. They were constructed in order to provide water to Baku and other residential areas. More than a million inhabitants of the peninsula have been provided with high quality and sustainable drinking water by this infrastructure. [ 5 ]
Intake pipelines were constructed for taking water from the reservoir by applying the tunnel boring machine method. A water distribution chamber was built on the shore of the reservoir in order to control volume of the supplied water and adjust raw water capacity to meet the needs of the plants. Four pipelines with a diameter of 1.4 meters were laid from the water distribution chamber to the UF treatment plant. [ 6 ]
30 km of pipelines in a varied diameter range, 242 km of electrical and 13 km of fiber optic cables, 7,120 tons of rebar, 3,000 tons of steel structure, and 65,000 cubic meters of concrete were used during the construction of the complex. Approximately 700,000 cubic meters of earthworks were constructed, 19,500 square meters of area were covered with asphalt, and greenery work was carried out in an area of 28,000 square meters. [ 7 ] | https://en.wikipedia.org/wiki/Jeyranbatan_Ultrafiltration_Water_Treatment_Plants_Complex |
A jib or jib arm is the horizontal or near-horizontal beam used in many types of crane to support the load clear of the main support. [ 1 ] [ 2 ] An archaic spelling is gib . [ 3 ]
Usually jib arms are attached to a vertical mast or tower or sometimes to an inclined boom . In other jib-less designs such as derricks , the load is hung directly from a boom which is often anomalously called a jib.
A camera jib or jib arm in cinematography is a small crane that holds nothing but the camera. [ 4 ]
This article about a mechanical engineering topic is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Jib_(crane) |
Jig concentrators are devices used mainly in the mining industry for mineral processing , to separate particles within the ore body, based on their specific gravity ( relative density ). [ 1 ]
The particles would usually be of a similar size, often crushed and screened prior to being fed over the jig bed . There are many variations in design; however the basic principles are constant: The particles are introduced to the jig bed (usually a screen) where they are thrust upward by a pulsing water column or body, resulting in the particles being suspended within the water. As the pulse dissipates, the water level returns to its lower starting position and the particles once again settle on the jig bed. As the particles are exposed to gravitational energy whilst in suspension within the water, those with a higher specific gravity (density) settle faster than those with a lower count, resulting in a concentration of material with higher density at the bottom, on the jig bed. The particles are now concentrated according to density and can be extracted from the jig bed separately. In the mining of most heavy minerals, the denser material would be the desired mineral and the rest would be discarded as floats (or tailings ).
There are some minerals, notably coal , that are lighter (lower in density) than the surrounding rock and in such instances the process of extraction would work in reverse, i.e. the coal would settle on top with the rock below (on the jig bed). There are several designs and methods of extraction from the jig bed.
This article about mining is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Jig_concentrators |
Jigar Shah (born August 30, 1974) was the director of the Loan Programs Office in the US Department of Energy from March 2021 to January 2025. [ 1 ] Since the passing of the Infrastructure Investment and Jobs Act and Inflation Reduction Act through Congress in 2021 and 2022, the funds to the Loan Programs Office increased tenfold from $40 billion to $400 billion in order to commercialize emerging clean energy technologies. [ 2 ] Shah led the office in administering loans to clean energy technologies majorly advancing the Biden Administration’s efforts to bring clean energy into the United States. [ 3 ]
Prior to the Loan Programs Office, Shah gained prominence as an American clean energy entrepreneur, author and podcast host. Shah is known for work to create and advocate for market-driven solutions to climate change . He authored the book Creating Climate Wealth: Unlocking the Impact Economy, published in 2013. [ 4 ]
Shah maintains that climate wealth is created when mainstream investors team up with entrepreneurs, corporations, mainstream capital, and governments at scale to solve the big problems of our time while generating compelling financial returns – not concessionary returns. [ 5 ]
Born in India, Shah moved to the United States with his family when he was one year old. Shah moved to Sterling , Illinois , when he was eight years old. [ 6 ]
Shah has attended public school from elementary school through his Masters. Shah holds a B.S. in Mechanical Engineering from the University of Illinois , Champaign-Urbana, [ 7 ] and an MBA from the University of Maryland . [ 8 ] [ 9 ]
Shah is the co-founder and President of Generate Capital. [ 10 ] Shah founded SunEdison in 2003, where he pioneered “no money down solar” and unlocked a multi-billion-dollar solar market, creating what was largest solar services company worldwide. The company simplified solar as a service through the implementation of the power purchase agreement (PPA) business model. That model changed the status quo, allowing organizations to purchase solar energy services under long-term predictably priced contracts and avoid the significant capital costs of ownership and operation of solar energy systems. Shah sold SunEdison in 2008.
Shah is author of Creating Climate Wealth: Unlocking the Impact Economy . The book talks about the prominent role of business model innovation, more than new technology, in attracting mainstream capital and unlocking transformational change. In the book, the author pictures reaching our 2020 climate change goals as means to create the next economy with the equivalent of 100,000 companies worldwide, each generating $100 million in sales. Shah argues that, while new technical innovation is valuable, deployment of existing technologies are the key to reaching our near-term climate targets.
He co-founded Carbon War Room with Richard Branson and Virgin United, an organization that worked to harness the power of entrepreneurship to deploy solution technologies at scale. He served as CEO from 2009 to 2012. [ 11 ]
Shah previously worked in strategy for BP Solar and as a contractor for the Department of Energy on alternative vehicles and fuel cell programs. [ 12 ]
Shah has also called to end all energy subsidies, including those for renewable energy, to "create a level playing field." [ 13 ] He has donated repeatedly to the Climate Hawks Vote Political Action Super PAC since 2016 per FEC records. [ 14 ]
Shah was a founding co-host of The Energy Gang, [ 15 ] a podcast dedicated to exploring the technological, political and market forces driving energy and environmental issues. On a 2017 episode, [ 16 ] Shah introduced the Jigar Shah Rule - "Countries should not have stupid policy". As noted by co-host Stephen Lacey, the new ruling is pulled directly from the Jigar Shah Playbook, which suggests you must have competitive options such as volumetric reductions and feed-in tariffs, and the way these were designed seven to eight years ago do not work.
Energy Secretary Jennifer Granholm appointed Shah to direct the United States Department of Energy 's Loan Programs Office (LPO) in March 2021. [ 17 ] [ 18 ] [ 19 ] The office initially provided $40 billion in loan authority to early-stage energy companies and climate technologies. [ 20 ] [ 21 ] [ 22 ] [ 23 ]
Under Shah, the LPO more than tripled its staff and reviewed more than 100 applications from climate tech companies seeking loans totaling more than $100 billion. [ 24 ]
With the passing of both bills (IRA and BIL) from Congress under the Biden Administration, Shah managed $400 billion of loan authority to commercialize and bring emerging technologies to market, create more clean energy jobs, and boost local economies. The most recent conditional commitment announced from the Loan Programs Office was to “finance the development of a solar-plus long-duration energy storage micro grid on the Tribal lands of Viejas Band of the Kumeyaay Indians near Alpine, California.” [ 25 ] This loan provides funding specifically for Tribes to plan for and adapt to climate change. [ 26 ] | https://en.wikipedia.org/wiki/Jigar_Shah |
A jiggle syphon (or siphon) is the combination of a syphon pipe and a simple priming pump that uses mechanical shaking action to pump enough liquid up the pipe to reach the highest point, and thus start the syphoning action.
The jiggle pump consists of a chamber, in line with the end of the pipe that sits in the liquid to be moved. The chamber is somewhat wider than the pipe, and narrows to approximately the pipe diameter at both ends. One end attaches to the pipe, the other end is open to the liquid. Within the chamber is a sphere, denser than the liquid to be pumped, small enough to move freely within the chamber but large enough to not be able to leave the chamber. [ 1 ]
To begin with, gravity holds the sphere at the bottom, open, end of the chamber, although hydrostatic pressure will force the liquid up and around the sphere upon immersion. When the pipe is vigorously shaken up and down, the sphere moves upwards, lifting some liquid in the pipe; then when it falls down again, the increased hydrostatic pressure within the pipe (which now has a higher head of fluid in it than the surrounding container) pushes the sphere down and prevents the liquid flowing back. Repeated "jigglings" lift the fluid up the pipe until it reaches the highest point in the pipe, whereupon gravity causes it to start to flow down the other side, and the syphon action will "suck" the liquid through the system. This causes the pressure in the pipe to drop below the hydrostatic pressure in the container, so the sphere is lifted upwards, allowing the liquid to flow. | https://en.wikipedia.org/wiki/Jiggle_syphon |
B. Jill Venton is a professor of chemistry at University of Virginia , where she serves as the department chair since 2019. [ 1 ] Venton's research focuses on developing analytical chemistry methods to enable detection of molecules in the brain.
Venton received her BS in Chemistry from University of Delaware in 1998 and her PhD in Chemistry from University of North Carolina, Chapel Hill in 2003. [ 1 ] [ 2 ] She was an NIH postdoctoral fellow at University of Michigan from 2003 to 2005.
Venton joined the Department of Chemistry at University of Virginia as an assistant professor in 2005, received tenure and was promoted to an associate professor in 2011, and was promoted to full professor in 2016. [ 2 ] Venton develops analytical tools such as carbon-fiber microelectrodes for sensing molecules in the brain [ 3 ] to achieve real-time monitoring of neurotransmitters to help understand the brain functions both under normal physiological conditions and in neurological disorders . [ 4 ] [ 5 ] [ 6 ]
B E Kumara Swamy; B. Jill Venton (5 July 2007). "Carbon nanotube-modified microelectrodes for simultaneous detection of dopamine and serotonin in vivo". Analyst . 132 (9): 876– 884. doi : 10.1039/B705552H . ISSN 0003-2654 . PMID 17710262 . Wikidata Q30444306 .
Cheng Yang; Madelaine E Denno; Poojan Pyakurel; B. Jill Venton (7 July 2015). "Recent trends in carbon nanomaterial-based electrochemical sensors for biomolecules: A review" . Analytica Chimica Acta . 887 : 17– 37. doi : 10.1016/J.ACA.2015.05.049 . ISSN 0003-2670 . PMC 4557208 . PMID 26320782 . Wikidata Q26796285 .
B. Jill Venton ; Qun Cao (1 February 2020). "Fundamentals of fast-scan cyclic voltammetry for dopamine detection". Analyst . 145 (4): 1158– 1168. doi : 10.1039/C9AN01586H . ISSN 0003-2654 . PMID 31922176 . Wikidata Q92545235 .
Qun Cao; Mimi Shin; Nickolay V Lavrik; B Jill Venton (19 August 2020). "3D-Printed Carbon Nanoelectrodes for In Vivo Neurotransmitter Sensing". Nano Letters . doi : 10.1021/ACS.NANOLETT.0C02844 . ISSN 1530-6984 . PMID 32813535 . Wikidata Q98566988 .
Mimi Shin; Jeffrey M Copeland; B. Jill Venton (13 October 2020). "Real-Time Measurement of Stimulated Dopamine Release in Compartments of the Adult Drosophila melanogaster Mushroom Body". Analytical Chemistry . doi : 10.1021/ACS.ANALCHEM.0C02305 . ISSN 0003-2700 . PMID 33048531 . Wikidata Q100529135 . | https://en.wikipedia.org/wiki/Jill_Venton |
Jameel Sadik " Jim " Al-Khalili ( Arabic : جميل صادق الخليلي ; born 20 September 1962) [ 4 ] is an Iraqi-British theoretical physicist and science populariser. He is professor of theoretical physics and chair in the public engagement in science at the University of Surrey . He is a regular broadcaster and presenter of science programmes on BBC radio and television, and a frequent commentator about science in other British media.
In 2014 Al-Khalili was named as a RISE (Recognising Inspirational Scientists and Engineers) leader by the UK's Engineering and Physical Sciences Research Council (EPSRC). [ 6 ] [ 7 ] He was President of Humanists UK between January 2013 and January 2016. [ 8 ] [ 9 ] [ 10 ]
Al-Khalili was born in Baghdad in 1962. [ 4 ] His father was an Iraqi Air Force engineer, and his English mother was a librarian. [ 5 ] Al-Khalili settled permanently in the United Kingdom in 1979. [ 4 ]
After completing (and retaking) his A-levels over three years until 1982, [ 5 ] he studied physics at the University of Surrey and graduated with a Bachelor of Science degree in 1986. He stayed on at Surrey to pursue a Doctor of Philosophy degree in nuclear reaction theory, which he obtained in 1989, rather than accepting a job offer from the National Physical Laboratory . [ 11 ]
In 1989, Al-Khalili was awarded a Science and Engineering Research Council (SERC) postdoctoral fellowship at University College London , after which he returned to Surrey in 1991, first as a research assistant, then as a lecturer. [ 12 ] In 1994, Al-Khalili was awarded an Engineering and Physical Sciences Research Council (EPSRC) Advanced Research Fellowship for five years, [ 13 ] during which time he established himself as a leading expert on mathematical models of exotic atomic nuclei . He has published widely in his field. [ 2 ] [ 14 ]
Al-Khalili is a professor of physics at the University of Surrey , where he also holds a chair in the Public Engagement in Science. [ 15 ] He has been a trustee (2006–2012) and vice president (2008–2011) of the British Science Association . [ 16 ] He also held an EPSRC Senior Media Fellowship. [ 13 ]
Al-Khalili was awarded the Royal Society of London Michael Faraday Prize for science communication for 2007 [ 17 ] and elected an Honorary Fellow of the British Association for the Advancement of Science . He has been a Fellow of the Institute of Physics since 2000, when he also received the Institute's Public Awareness of Physics Award. [ 18 ] He has lectured widely both in the UK and around the world, particularly for the British Council . He is a member of the British Council Science and Engineering Advisory Group, [ 19 ] a member of the Royal Society Equality and Diversity Panel, [ 20 ] an external examiner for the Open University Department of Physics and Astronomy, a member of the Editorial Board for the open access Journal PMC Physics A, and Associate Editor of Advanced Science Letters. He is also a member of the Advisory Committee for the Cheltenham Science Festival .
In 2007, he was a judge on the BBC Samuel Johnson Prize [ 21 ] for non-fiction and has been a celebrity judge at the National Science & Engineering Competition Finals at The Big Bang Fair. He was appointed Officer of the Order of the British Empire (OBE) in the 2008 Birthday Honours . [ 22 ] In 2012, he delivered the Gifford Lectures on Alan Turing: Legacy of a Code Breaker at the University of Edinburgh . [ 23 ] In 2013 he was awarded an Honorary Degree (DSc) from the University of London. [ 24 ] Al-Khalili was elected as a Fellow of the Royal Society in 2018 [ 25 ] and elected an Honorary Fellow of the Royal Academy of Engineering in 2023. [ 26 ]
He was appointed Commander of the Order of the British Empire (CBE) in the 2021 Birthday Honours for services to science and public engagement in STEM . [ 27 ]
As a broadcaster, Al-Khalili is frequently on television and radio and also writes articles for the British press. [ 28 ] [ 29 ] In 2004, he co-presented the Channel 4 documentary The Riddle of Einstein's Brain , produced by Icon Films . [ 30 ] His big break as a presenter came in 2007 with Atom , a three-part series on BBC Four about the history of our understanding of the atom and atomic physics. [ 31 ] This was followed by a special archive edition of Horizon , "The Big Bang". [ 32 ]
In early 2009, Al-Khalili presented the BBC Four three-part series Science and Islam about the leap in scientific knowledge that took place in the Islamic world between the 8th and 14th centuries. [ 33 ] He has contributed to programmes ranging from Tomorrow's World , BBC Four's Mind Games , The South Bank Show to BBC One 's Bang Goes the Theory . [ 34 ] In 2010 he presented the BBC documentary on the history of chemistry , Chemistry: A Volatile History . [ 35 ] In October 2011, he began a programme on famous contemporary scientists on Radio Four , called The Life Scientific . [ 36 ] The first of this series featured his interview with Paul Nurse . [ 37 ] He has since interviewed a series of notable scientists, including Richard Dawkins , Alice Roberts , James Lovelock , Steven Pinker , Martin Rees , Jocelyn Bell Burnell , Mark Walport and Tim Hunt , and he has himself been interviewed on the show by Adam Rutherford .
Al-Khalili hosts a regular "Jim meets..." interview series at the University of Surrey , which is published on the university's YouTube channel. Guests have included David Attenborough , Robert Winston , Brian Cox and Rowan Williams , Archbishop of Canterbury . [ 38 ] In 2011, Al-Khalili hosted a three-part documentary series on BBC Four entitled Shock and Awe: The Story of Electricity . [ 39 ] In 2012, Al-Khalili presented a Horizon special on BBC 2 , which examined the latest scientific developments in the quest to discover the Higgs Boson , with preliminary results from the Large Hadron Collider experiment at CERN suggesting that the elusive particle does indeed exist.
Al-Khalili has been one of the experts interviewed in the Philomena Cunk mockumentaries Cunk on Earth (2022) and Cunk on Life (2024). [ 40 ] [ 41 ] [ 42 ]
Al-Khalili lives in Southsea , Portsmouth , with his wife Julie. [ 5 ] They have a son and daughter.
Al-Khalili is an atheist and a humanist , [ 48 ] remarking, "as the son of a Protestant Christian mother and a Shia Muslim father, I have nevertheless ended up without a religious bone in my body". [ 49 ] Al-Khalili became vice president of Humanists UK in 2016 after stepping down as its president. [ 50 ]
He is also a patron of Guildford-based educational, cultural and social community hub, The Guildford Institute. [ 51 ]
A list of Jim Al-Khalili's peer reviewed research papers can be found on Google Scholar [ 2 ] and Scopus . [ 7 ] His published books include:
His essays, chapters and other contributions include:
Jim Al-Khalili has written one science fiction novel: | https://en.wikipedia.org/wiki/Jim_Al-Khalili |
Jim Falk (born 26 October 1946) is an Australian physicist and academic researcher on science and technology studies .
Falk was born in Oxford , England. His father was the philosopher Werner D. Falk (latterly professor at the University of North Carolina [ 1 ] ), and his mother an Australian, Dr. Barbara Cohen. [ 2 ] [ non-primary source needed ] Werner Falk had fled Germany prior to World War II and was studying and lecturing at the University of Oxford. [ 3 ] [ non-primary source needed ] The family moved to Australia when Jim Falk was young, when his father worked at the University of Melbourne. Falk attended Scotch College from 1952 to 1964, graduated with first class honours in physics at Monash University in 1968, [ citation needed ] and received his PhD from Monash in theoretical quantum physics in 1974. [ citation needed ] His late partner for 47 years was Emeritus Professor Sue Rowley (1948-2016), with whom he had two children. [ 4 ] Jim Falk lives in Melbourne. [ citation needed ]
In December 2010 he retired, but remained an honorary professorial fellow in the Melbourne Sustainable Society Institute , at the University of Melbourne . He was the founding director of Climate Change research for the Association of Pacific Rim Universities World Institute, and holds appointments also of visiting professor to the Institute of Advanced Studies of Sustainability at the United Nations University (in Yokohama , Japan ), and emeritus professor at the University of Wollongong . [ citation needed ]
For over 35 years Falk has studied science and technology in their social contexts. [ 5 ] He has worked towards advancing understanding of the political, economic and cultural factors which constrain or facilitate the exercise of social control over technological change, latterly in relation to climate change and information technology but particularly nuclear technology , arms races and militarisation . Most recently [ when? ] he has focused on the broad issues of human governance (including what needs to be done to respond to challenges faced by humanity from climate change, to energy policy, and to issues associated with information flows and military threats). [ citation needed ]
One of Falk's books, co-authored with Joseph Camilleri, was launched by UNDP head, the Hon Helen Clark, in Sydney, Australia in February 2010. The book "Worlds in Transition: Evolving Governance Across a Stressed Planet", Edward Elgar, UK, is a synoptic overview of the way in which humans have come to collectively seek to shape their futures, and the challenges posed to that in a time of rapid transition. [ 6 ] [ 7 ]
Falk has made a number of media appearances in relation to the nuclear accidents at Fukushima and the implications for future energy policy. Jim Falk has recently [ when? ] authored a short e-book "Things that Count: the rise and fall of calculators" on the social history of calculation technology. It can be downloaded from a website he maintains on the subject. [ tone ] [ 8 ] His current [ when? ] scholarly work is on the proposals associated with geoengineering , which were the subject of a seminar he presented at the United Nations University Institute of Advanced Studies in Yokohama , Japan, in October 2013. [ 9 ] | https://en.wikipedia.org/wiki/Jim_Falk |
William James Kent (born February 10, 1960) is an American research scientist and computer programmer . He has been a contributor to genome database projects and the 2003 winner of the Benjamin Franklin Award .
Kent was born in Hawaii and grew up in San Francisco, California , United States .
Kent began his programming career in 1983 with Island Graphics Inc. where he wrote the Aegis Animator program for the Amiga home computer. This program combined polygon tweening in 3D with simple 2D cel-based animation. In 1985 he founded and ran a software company, Dancing Flame, which adapted the Aegis Animator to the Atari ST , [ 2 ] and created Cyber Paint [ 3 ] [ 4 ] for that machine. Cyber Paint was a 2D animation program that brought together a wide variety of animation and paint functionality and the delta-compressed animation format developed for CAD-3D. The user could move freely between animation frames and paint arbitrarily, or utilize various animation tools for automatic tweening movement across frames. Cyber Paint was one of the first, if not the first, consumer program that enabled the user to paint across time in a compressed digital video format. Later he developed a similar program, the Autodesk Animator for PC compatibles , where the image compression improved to the point it could play off of hard disk, and one could paint using "inks" that performed algorithmic transformations such as smoothing, transparency, and tiled patterns. The Autodesk Animator was used to create artwork for a wide variety of video games. [ 5 ]
In 2000, he wrote a program, GigAssembler, [ 6 ] that allowed the publicly funded Human Genome Project to assemble and publish the first human genome sequence. His efforts were motivated by the research needs of himself and his colleagues, but also out of concern that the data might be made proprietary via patents by Celera Genomics . [ 7 ] In their close race with Celera, Kent and the UCSC Professor David Haussler quickly built a modest cluster of 50 commodity personal computers running a Linux-based operating system to run the software. In contrast, Celera was using what was thought then to be one of the most powerful civilian supercomputers in the world. Kent's first assembly on the human genome was released on June 22. Celera finished its assembly three days later on June 25, and the dual results were announced at the White House on June 26. On July 7, 2000, the Santa Cruz data was made publicly available on the World Wide Web while the research paper describing this publicly funded genome was published in February 2001 special issue of Nature , [ 8 ] in parallel with Celera's results in the journal Science . [ 9 ] In 2002 Tim O'Reilly described Kent's work as "the most significant work of open source development in the past year". While all of Kent's genomics software is open source in the sense that the source code can be downloaded and read for free, and all of the software can be freely used for academic, nonprofit, and personal use, some of it requires a license , either from UCSC or from Kent Informatics Inc., for commercial use. [ 10 ]
After GigAssembler, Kent went on to write BLAT (BLAST-like alignment tool) [ 11 ] and the UCSC Genome Browser [ 12 ] to help analyze important genome data. Kent continues to work at UCSC primarily on web tools to help understand the human genome. He helps maintain and upgrade the browser, and has worked on comparative genomics , [ 13 ] Parasol, a job control management software for the UCSC kilocluster, and the ENCODE Project. | https://en.wikipedia.org/wiki/Jim_Kent |
Jimm is an alternative open-source instant messaging client for the ICQ network. It is written in Java ME and should work in most of mobile devices that follow MIDP specification.
Jimm is licensed under the terms of the GNU General Public License .
Creator of Jimm is Manuel Linsmayer. In 2003 he released a client Mobicq . The client allows to view a list of contacts and exchange messages on a protocol OSCAR (ICQ v8).
In 2004 AOL banned the use of the name "Mobicq" because it contains a part belonging to company trademark "ICQ". At that time, client was able to display status, display information about user, play sounds and display messages in the chat. It was decided to rename Mobicq to Jimm. The name "Jimm" means "Java Instant Mobile Messenger".
This software article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Jimm |
Jing Li ( Chinese : 李静 ) [ 1 ] is a Board of Governors Professor of Chemistry and Chemical Biology at Rutgers University , New Jersey , United States . She and her team are engaged in solid-state , inorganic and inorganic-organic hybrid materials research. [ 2 ] Her current research focuses on designing and developing new functional materials including metal-organic frameworks and hybrid semiconductors for applications in the field of renewable and sustainable energy, and clean environment.
Li’s research has resulted in 12 issued patents and over 460 publications [ 3 ] (articles, invited book chapters, feature and review papers), in high impact factor journals such as Science Magazine , Nature Communications , the Journal of the American Chemical Society ( JACS ), Advanced Materials and Angewandte Chemie International Edition . She was selected as a Highly Cited Researcher by Thomson Reuters [ 4 ] in 2015 and 2016, and by Clarivate Analytics [ 5 ] in 2019, 2020 and 2022. [ 6 ]
Li completed her undergraduate studies in China, and received her master's degree from the State University of New York at Albany .
She obtained her PhD degree in January 1990 at Cornell University under the supervision of Professor Roald Hoffmann , the 1981 Nobel Prize laureate in Chemistry . [ 7 ] She continued to work at Cornell as a postdoc for two years (1989–1991) with Professor Francis "Frank" J. DiSalvo before taking an academic position at Rutgers University . [ 8 ]
Li joined the Rutgers Faculty as an assistant professor in 1991, where she was promoted to associate professor in 1996, full professor in 1999, and distinguished professor in 2006. [ 9 ] Her current research group consists of postdoc associates, graduate students, visiting scientists, exchange graduate students and undergraduate students. [ 10 ] Li has developed and taught 17 different undergraduate and graduate courses since her first appointment with the university.
Li’s focus of research includes areas of solid-state inorganic and materials chemistry. Her current research focuses on the development of new and functional materials that are fundamentally important and relevant for clean and renewable energy applications. These include (a) metal organic frameworks (MOFs) for gas storage and separation, carbon dioxide capture, waste remediation and chemical sensing, [ 11 ] [ 12 ] [ 13 ] [ 14 ] [ 15 ] [ 16 ] [ 17 ] and energy efficient lighting applications; [ 18 ] [ 19 ] These materials are made of a metal ion or metal cluster such as transition metals and organic ligands such as carboxylate groups and nitrogen containing molecules; (b) inorganic-organic hybrid semiconductors for optoelectronic devices such as photovoltaics and solid-state lighting. [ 20 ] [ 21 ] [ 22 ] [ 23 ] [ 24 ] These crystalline compounds consist of both inorganic and organic structure motifs. They combine the good features of the two components, resulting in enhanced and improved properties.
Jing Li has received numerous awards and honors for her academic achievements, including: | https://en.wikipedia.org/wiki/Jing_Li_(chemist) |
Jinhua Ye is a Chinese chemist who is a professor at the National Institute for Materials Science in Tsukuba . Her research considers high-temperature superconductors for photocatalysis. She was elected Fellow of the Royal Society of Chemistry in 2016 and has been included in the Clarivate Analytics Highly Cited Researcher every year since then.
Ye became interested in science fiction as a child. [ 1 ] She was particularly interested in a story by Ye Yonglie that included a castle made from diamond. [ 1 ] Ye learned that photocatalysis could split water into hydrogen and oxygen. She then became inspired by Jules Verne 's The Mysterious Island ,
I believe that water will one day be employed as fuel, that hydrogen and oxygen which constitute it, used singly or together, will furnish an inexhaustible source of heat and light, of an intensity of which coal is not capable. [ 2 ]
She studied chemistry at the Zhejiang University . [ 3 ] After completing her undergraduate degree, she moved to Japan , where she joined the University of Tokyo . After earning her doctorate in 1990, she joined Osaka University as a research associate. [ 4 ]
In 1991, Ye joined the National Institute for Materials Science . [ 3 ] She was made Director of Photocatalytic Materials Center in 2006 and Director of Environmental Remediation Materials in 2011. [ 3 ]
Ye has dedicated her career to the realization of artificial photosynthesis. [ 5 ] She is particularly interested in the development of materials that harvest the most sunlight. Ye has studied the reaction mechanisms, and, in an effort to overcome harsh reaction kinetics, has worked on the careful construction of interfaces. In particular, Ye has developed nano-structured surfaces [ 6 ] that enhance reactivities, and, using localized surface plasmon resonance, broaden the spectral range of her photocatalytic materials. [ 7 ]
Ye was elected Fellow of the Royal Society of Chemistry in 2016. [ 8 ] In 2022, she was included by the American Chemical Society Energy Letters in their list of the world's leading women scientists in energy research. [ 1 ] | https://en.wikipedia.org/wiki/Jinhua_Ye |
Jinitiator is a Java virtual machine (JVM) made and distributed by Oracle Corporation . It allows a web enabled Oracle Forms client application to be run inside a web browser . This JVM is called only when a web-based Oracle application is accessed. This behavior is implemented by a plugin or an activex control, depending on the browser.
The first two numbers of the version roughly follow the Sun Java numbering convention. It means that for instance Jinitiator 1.3.1.25 is based upon JDK 1.3 or later.
The main reason for Oracle to develop Jinitiator was to support Oracle Forms on the web in earlier releases due to bugs in earlier releases of the JDK.
In 2007 Oracle announced, that for the upcoming release of Forms version 11, Jinitiator would no longer be needed [ 1 ] [ 2 ] and that users should migrate to the Sun Java plug-in. [ 3 ] In January 2010, a product obsolescence desupport notice was posted saying that JInitiator would no longer be supported and that all users should upgrade. [ 4 ] Since version 10.1.2.0.2 of Forms in 2010, Oracle began working closely with Sun to completely phase out Jinitiator. [ 5 ]
The latest version (released in 2008) is 1.3.1.30 and is still available at the Oracle website. Obsolete versions of Jinitiator can be made to work under Windows 7 with Internet Explorer 9 , but this approach is not supported or recommended by Oracle. [ 3 ] [ 6 ]
This software article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Jinitiator |
Jiuzhang ( Chinese : 九章 ) is the first photonic quantum computer to claim quantum supremacy . Previously quantum supremacy has been achieved only once, in 2019, by Google's Sycamore ; however, Google's computer was based on superconducting materials, and not photons. [ 1 ]
Jiuzhang was developed by a team from University of Science and Technology of China (USTC) led by Pan Jianwei and Lu Chaoyang . The computer is named after Jiuzhang suanshu , an ancient Chinese mathematical classic book.
On 3 December 2020, USTC announced in Science that Jiuzhang successfully performed Gaussian boson sampling in 200 seconds (3 minutes 20 seconds), with a maximum of 76 detected photons. The USTC group estimated that it would take 2.5 billion years for the Sunway TaihuLight supercomputer to perform the same calculation. [ 2 ]
The setup involves a Verdi- pumped Mira 900 Ti:sapphire laser which is split into 13 paths of equal intensity and then shined on 25 PPKTP crystals to produce 25 two-mode squeezed states . Through a hybrid encoding this is equivalent to 50 single-mode squeezed states. The purity is increased from 98% to 99% by 12 nm filtering . The 50 single-mode squeezed states are sent into a 100-mode interferometer and sampled by 100 single-photon detectors with an efficiency of 81%. [ citation needed ] | https://en.wikipedia.org/wiki/Jiuzhang_(quantum_computer) |
The Jizera Dark Sky Park ( Polish : Izerski Park Ciemnego Nieba - IPCN , Czech : Jizerská oblast tmavé oblohy - JOTO ) is the first transnational dark-sky preserve . It is located in a nearly-uninhabited region of the Jizera Mountains that lies halfway between Poland and the Czech Republic . The park primarily serves to inform the general public about the issue of light pollution , as well as to protect nature and the environment . [ 1 ]
The initiative to create a dark-sky preserve in the Jizera Mountains came from the Astronomical Institute of the University of Wrocław in Poland. It was joined by other institutions, namely the Astronomical Institute of the Academy of Sciences of the Czech Republic , the Nature and Landscape Protection Agency of the Czech Republic [ cz ] , the administration of the Jizera Mountains Protected Area, the Świeradów Zdroj Forest District, the Szklarska Poreba Forest District, the state enterprise Forests of the Czech Republic [ cz ] , and the regional directorate of Liberec . On November 4, 2009, as part of the United Nations ' International Year of Astronomy , these institutions jointly declared the Jizera Dark Sky Region. [ 2 ]
The Jizera region of dark skies covers an area of almost 75 square kilometres (29 sq mi). It is located in an nearly uninhabited part of the Jizera Mountains and lies halfway between the Czech and Polish sides of the mountain range. On the Czech side, it stretches from the settlement of Jizerka to Mount Smrk , while in Poland it continues along the High Jizera ridge and surrounds the Jizera Meadow and the settlement of Orle. [ 3 ]
The park has several functions. Above all, it informs the general public about the issue of light pollution by showcasing its night sky as much darker than the sky in cities and their surroundings. [ 1 ] Another important function is the protection of nature and the environment. The park hosts a number of astronomical events for the public such as lectures and sky observations, in which the Club of Astronomers Liberecka branch of the Czech Astronomical Society and other institutions take part. [ 4 ] On the Polish side, the park is part of the astro-tourism project Astro Izery. [ 5 ]
Although the night sky in the Jizera dark sky region is significantly darker than in the cities, it is not as naturally dark as it would be with no light from Earth. The influence of light pollution from cities stretches tens of kilometers away. The brightness of the sky in Jizerka is approximately twice as high as a naturally dark sky without the influence of light pollution. [ 6 ] Naturally dark night skies effectively do not occur in the densely populated Central Europe region. [ 7 ] The most prominent sources of light pollution that can be seen from the area are the cities of Liberec, Jablonec and Nisou , Tanvald , and Jelenia Góra . [ 8 ] The sky quality of that park expressed by the Bortle scale is at level 4, and reaches level 3 under exceptionally good conditions. [ 9 ] [ 10 ] | https://en.wikipedia.org/wiki/Jizera_Dark-Sky_Park |
Jiří Drahoš (born 20 February 1949; Czech pronunciation: [ˈjɪr̝iː ˈdraɦoʃ] ) is a Czech physical chemist and politician who has been the Senator of Prague 4 since October 2018. Previously, Drahoš served as President of the Czech Academy of Sciences from 2009 to 2017, and was a candidate in the 2018 Czech presidential election .
Born in Český Těšín and raised in nearby Jablunkov , Drahoš studied physical chemistry at the University of Chemistry and Technology in Prague, and joined the Institute of Chemical Process Fundamentals of the Czechoslovak Academy of Sciences in 1973, which he later led from 1995 to 2003. In 2009, he was elected President of the Czech Academy of Sciences. His term as head of the academy ended on 24 March 2017.
In March 2017, Drahoš announced his candidacy for President of the Czech Republic in the 2018 election . He ran on a moderate centrist platform, and is generally pro-European and supportive of NATO and Atlanticism . Drahoš lost the second round of the presidential election to his opponent President Miloš Zeman with 48.6% of the vote, but vowed to remain in public life. In October 2018, he stood for the Czech Senate in the Prague 4 district, winning the election outright in the first round with 52.65% of the vote. [ 1 ] [ 2 ]
He is a member of the European Academy of Sciences and Arts . [ 3 ]
Jiří Drahoš was born on 20 February 1949 in Český Těšín to a Czech father originally from Skuteč in Vysočina , and a Polish mother from Jablunkov. [ 4 ] He spent most of his childhood in Jablunkov , where his mother Anna lived and worked as a nurse. His father, also named Jiří, was a teacher in a local Czech school.
Drahoš studied at the University of Chemistry and Technology in Prague and qualified as a scientist in 1972. He joined the Institute of Chemical Process Fundamentals at the Czech Academy of Sciences , and was later head of the institute from 1996 to 2003. [ 5 ] On 13 March 2009, Drahoš was elected President of the Czech Academy of Sciences , [ 6 ] defeating Eva Syková . During his tenure, he successfully opposed 50% budget cuts to the Academy proposed by the governments of Prime Ministers Mirek Topolánek and Jan Fischer as a consequence of the 2008 financial crisis . Drahoš later called it an "attempt to destroy my motherly institution". [ 7 ] In 2012, President Václav Klaus awarded him the Medal of Merit in the field of science. His second term as head of the academy ended on 24 March 2017. He is co-author of 14 patents. [ 8 ]
On 28 March 2017, Drahoš announced his intention to stand in the 2018 presidential election . [ 9 ] On 24 April 2017, he started gathering the signatures required to be registered as a candidate. [ 10 ] In July 2017, after meeting with Drahoš, the leaders of Populars and Mayors , Pavel Bělobrádek and Petr Gazdík , announced that they would ask their respective parties' members to nominate and endorse Drahoš's candidacy. Mayors and Independents endorsed Drahoš on 25 July 2017 while the Christian and Democratic Union – Czechoslovak People's Party (KDU–ČSL) endorsed him on 14 November 2017. [ 11 ] [ 12 ] Young Social Democrats also endorsed Drahoš on 9 December 2017. [ 13 ] Polls in late 2017 showed Drahoš as the second strongest candidate behind Zeman. [ 14 ] [ 15 ]
Drahoš received campaign donations from several influential businessmen, including Dalibor Dědek , Jiří Grygar and Luděk Sekyra . [ 16 ] [ 17 ] Drahoš started gathering signatures for his nomination in May 2017. [ 18 ] On 19 August 2017, Drahoš announced he had gathered 78,000 signatures. [ 19 ] He submitted his nomination on 3 November 2017 with 142,000 signatures. [ 20 ]
On 4 November 2017 on Facebook, Drahoš criticized Mirek Topolánek , who had announced his candidacy that day, describing Topolánek as similar to Miloš Zeman and calling his candidacy a bad joke. [ 21 ] The two candidates met during a presidential debate at Charles University ; Drahoš reflected that the status he posted was "Topolánek-like", to which Topolánek replied that it was written either by "a woman or PR mage". [ 22 ]
Drahoš received media attention when he expressed his fear that the election could be influenced by Russia. He met outgoing Prime Minister Bohuslav Sobotka to discuss the matter and stated he would also meet the new Prime Minister Andrej Babiš . [ 23 ] The incumbent president Miloš Zeman criticized Drahoš and compared his actions to Hillary Clinton 's when she lost to Donald Trump . [ 24 ]
Drahoš received criticism when he published a status on social media about Václav Klaus ' amnesty, when it was revealed that he had copied a similar status by his fellow presidential candidate Michal Horáček . Drahoš apologised and attributed the mistake to an external member of staff. [ 25 ]
The first round was held on 12 and 13 January 2018. Drahoš received 1,369,601 (26.6%) votes, [ 26 ] and advanced to the second round against the incumbent president Miloš Zeman . [ 27 ] In the second round, held on 26–27 January 2018, Drahoš received 48.63% of the vote and thus lost to Zeman. [ 28 ] Drahoš conceded defeat to Zeman, telling a crowd of his supporters that "I would like to congratulate election winner Miloš Zeman". [ 29 ]
Following the 2018 presidential election, Drahoš vowed to remain in public life, and in March 2018 announced his bid for the Prague 4 Senate seat in the 2018 election , nominated by Mayors and Independents and supported by TOP 09 , KDU–ČSL and the Green Party . [ 30 ] He won the election outright in the first round, with 52.65% of the vote. [ 1 ] [ 2 ]
At the beginning of November 2022, Drahoš was elected 1st Deputy President of the Czech Senate replacing Jiří Růžička , having received 67 out of 80 votes in a secret ballot. [ 31 ]
In the 2024 Czech Senate elections , he defended his seat as a non-party member of STAN in Senate District No.20 - Prague 4, with the support of STAN, Pirates, ODS, KDU-ČSL and TOP 09. [ 32 ] [ 33 ] He won the first round of the election, receiving 48.21 % of the vote. On 30 October 2024, he was re-elected as the 1st Deputy President of the Senate, with 61 votes from the 79 senators present. [ 34 ]
Drahoš considers himself a centrist politician. As a candidate, Jiří Drahoš has presented himself as someone who can unite society, and as a respectable person who would act according to the constitution . Drahoš emphasises the importance of Czech science and education and has called for solidarity with those "who cannot take care of themselves". [ 35 ] [ 36 ] He has called for a "responsible approach" to the landscape and environment and has described human reason, creativity and ingeniousness as the only "renewable resource" of the wealth of the Czech Republic. [ 36 ]
Drahoš wants the Czech Republic to play an active role in discussions over the future of the European Union , and wants the country to be a part of the Western world . [ 37 ] He supports European integration but has said that he believes that the European Union should not impose unnecessary regulations on member states. He also said that he would not rush into Czech adoption of the Euro . [ 38 ] Drahoš opposes a referendum about Czech membership of the European Union , and said that important geopolitical questions should not be decided by referendum. [ 37 ] He supports the Czech Republic's membership of NATO .
In August 2015, Drahoš signed a petition named "scientists against fear and apathy" in opposition to both anti-Islamic radicalism and anti-immigrant populism. [ 39 ]
Drahoš suggested that the Catalan independence referendum was "not legal", supporting the position of the Spanish government . [ 40 ]
In 2017, Drahoš said he supports the sanctions against Russia imposed by the United States and the EU. [ 41 ] However he also said that having good relations with Russia is in the interest of the Czech Republic and European Union. [ 41 ] Drahoš supports trade and economic relations with China , arguing that "China is a superpower" and "many countries are doing business with China." [ 42 ]
In 2017, Drahoš rejected the European Union's proposal of compulsory migrant quotas , saying, "there is no successful model of Muslim integration in Europe". [ 43 ] Drahoš also said that "Europe can't feed 100 million Africans, it is necessary to help them at home." [ 43 ]
Drahoš described the pre-war German minority in Czechoslovakia as "Adolf Hitler's fifth column", and said that he agreed with the post-war expulsion of Germans from Czechoslovakia . [ 44 ]
Drahoš has described himself as a sympathizer with Israel . [ 45 ] | https://en.wikipedia.org/wiki/Jiří_Drahoš |
Jiří Linhart (13 April 1924 – 6 January 2011) [ 1 ] Nuclear fusion physicist and Czech Olympic swimmer . He competed in the men's 200 metre breaststroke at the 1948 Summer Olympics in London. [ 2 ] He stayed on in London [ citation needed ] after which he took his PhD under the supervision of Denis Gabor . He was a pioneer of Nuclear Fusion, author of "Plasma Physics" (1960) - the first textbook on Plasma science , and many academic papers and early patents on nuclear reactors .
In 1956 he became group Head of Acceleration at CERN , and in 1960 he became the head of the EURATOM group in Frascati.
He was also a very keen chess player, playing in the Haifa Olympiad in 1976.
This biographical article related to a Czech swimmer is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Jiří_Linhart |
Jmol is computer software for molecular modelling of chemical structures in 3 dimensions . [ 2 ] It is an open-source Java viewer for chemical structures in 3D . [ 3 ] The name originated from [ J ]ava (the programming language) + [mol]ecules, and also the mol file format .
JSmol is an implementation in JavaScript of the functionality of Jmol. [ 4 ] It can hence be embedded in web pages to display interactive 3D models of molecules and other structures without the need for any software apart from the web browser ( it does not use Java ).
Both Jmol and JSmol render an interactive 3D representation of a molecule or other structure that may be used as a teaching tool, [ 5 ] or for research, in several fields, e.g. chemistry , biochemistry , materials science , crystallography , [ 6 ] symmetry or nanotechnology .
Jmol is written in the programming language Java , so it can run on different operating systems: Windows , macOS , Linux , and Unix , as long as they have Java installed. It is free and open-source software released under the GNU Lesser General Public License (LGPL) version 2.0. The interface in translated into more than 20 languages.
There are several products implemented:
Molecules can be displayed in different styles of rendering, like ball-and-stick models , space-filling models , ribbon diagrams , molecular surfaces , etc. [ 7 ] Jmol supports a wide range of chemical file formats , including Protein Data Bank (pdb), Crystallographic Information File (cif and mmcif), MDL Molfile (mol and sdf), and Chemical Markup Language (CML).
It can also display other types of files for structures with 3D data.
JSmol replaced the Jmol Java applet, which in turn had been previously developed as an alternative to the Chime plug-in, [ 5 ] both of which became unsupported by web browsers. Jmol was initiated [ 8 ] to reproduce functions present in Chime (with the exception of the Sculpt mode) and has been continuously growing in features, surpassing the simple display of molecular structures. Most notably, it has a large set of commands and a thorough scripting language ( JmolScript ) [ 9 ] that includes many characteristics of a programming language, such as variables, arrays, mathematical and Boolean operators, SQL -like queries, functions, loops, conditionals, try-catch, switch... | https://en.wikipedia.org/wiki/Jmol |
JoAnn Clayton Townsend (née Cleveland, 1935–2020) was an American science policy analyst, the director of the Aeronautics and Space Engineering Board of the National Academy of Sciences . [ 1 ] [ 2 ] [ 3 ]
Townsend was born in 1935 in Fort Smith, Arkansas , the daughter of James William Woolley Cleveland and Rachel Blanch Mary McLaughlin. She was raised in Tulsa, Oklahoma , by her mother, "in extreme poverty". She became a student at the University of Tulsa , on a full scholarship, and graduated Phi Beta Kappa . [ 1 ]
In 1955 she married John Clayton, a news reporter. He joined the United States Information Service in 1957, and from 1957 to 1974 she traveled with him to posts around the world. They had a daughter, born in 1959 in Madras , India, and a son, born in 1962 in Tehran , Iran. [ 1 ]
From 1963 until 1966, while her husband was posted in Washington, D.C. , Townsend became an assistant to the foreign secretary of the National Academy of Sciences . The family returned to the US again in 1974, and Townsend became an assistant to three members of congress, Berkley Bedell , Charles W. Whalen Jr. , and Matthew J. Rinaldo . [ 1 ]
John Clayton died on June 17, 1977. [ 1 ] In 1979, Townsend returned to the National Academy of Sciences staff. [ 2 ] Her interest there in space science began with an early assignment to report on Ronald Reagan 's 1981 cancellation of funding for a joint solar observation mission between NASA and the European Space Agency [ 1 ] that, eventually revived and delayed by the cancellation of the Space Shuttle program, became the Ulysses space probe . [ 4 ] During this period, Townsend also returned to school to receive a master's degree in space policy from George Washington University . Soon afterward, she became director of the academy's Aeronautics and Space Engineering Board. [ 1 ] She also belonged to the International Institute of Space Law and the International Academy of Astronautics , and became the editor of the annual proceedings of the International Institute of Space Law. [ 2 ]
In 1996, she married John W. Townsend Jr., [ 1 ] a widowed former president of Fairchild Industries Space Division and former director of the Goddard Space Flight Center . [ 5 ] She retired in 1997, and in her retirement became a painter of abstract art, affiliated with the Torpedo Factory Art Center . [ 1 ] She became artist in residence at Glen Echo Park (Maryland) for a month in 2011. [ 6 ]
Her second husband, Jack Townsend, died of lung cancer on October 29, 2011. [ 5 ] Townsend and her daughter moved in 2012 to Maine , where her son and his family lived. She died on December 21, 2020. [ 1 ]
Townsend received the 1991 Outstanding Achievement Award and the 1997 Outstanding Member Award of Women in Aerospace. [ 1 ] [ 7 ] She was named as a Fellow of the American Institute of Aeronautics and Astronautics in 2003. [ 8 ] | https://en.wikipedia.org/wiki/JoAnn_Clayton_Townsend |
Joachim "Jim" Lambek FRSC (5 December 1922 – 23 June 2014) [ 2 ] was a Canadian mathematician . He was Peter Redpath Emeritus Professor of Pure Mathematics at McGill University , where he earned his PhD degree in 1950 with Hans Zassenhaus as advisor.
Lambek was born in Leipzig , Germany , where he attended a Gymnasium . [ 3 ] He came to England in 1938 as a refugee on the Kindertransport . [ 2 ] From there he was interned as an enemy alien and deported to a prison work camp in New Brunswick , Canada . There, he began in his spare time a mathematical apprenticeship with Fritz Rothberger, also
interned, and wrote the McGill Junior Matriculation in fall of 1941. [ 3 ] In the spring of 1942, he was released and settled in Montreal , where he entered studies at McGill University, graduating with an honours mathematics degree in 1945 and an MSc a year later. [ 4 ] In 1950, he completed his doctorate under Hans Zassenhaus becoming McGill's first PhD in mathematics.
Lambek became assistant professor at McGill; he was made a full professor in 1963. He spent his sabbatical year 1965–66 in at the Institute for Mathematical Research at ETH Zurich , where Beno Eckmann had gathered together a group of researchers interested in algebraic topology and category theory , including Bill Lawvere . There Lambek reoriented his research into category theory. [ 5 ]
Lambek retired in 1992 but continued his involvement at McGill's mathematics department . In 2000 a festschrift celebrating Lambek's contributions to mathematical structures in computer science was published. [ 6 ] On the occasion of Lambek's 90th birthday, a collection Categories and Types in Logic, Language, and Physics was produced in tribute to him. [ 7 ]
Lambek's PhD thesis investigated vector fields using the biquaternion algebra over Minkowski space , as well as semigroup immersion in a group . The second component was published by the Canadian Journal of Mathematics . [ 8 ] He later returned to biquaternions when in 1995 he contributed "If Hamilton had prevailed: Quaternions in Physics", which exhibited the Riemann–Silberstein bivector to express the free-space electromagnetic equations.
Lambek supervised 17 doctoral students, and has 75 doctoral descendants as of 2020. [ 9 ] He has over 100 publications listed in the Mathematical Reviews , including 6 books. His earlier work was mostly in module theory , especially torsion theories, non-commutative localization, and injective modules . One of his earliest papers, Lambek & Moser (1954) , proved the Lambek–Moser theorem about integer sequences. In 1963 he published an important result, now known as Lambek's theorem, on character modules characterizing flatness of a module. [ 10 ] His more recent work is in pregroups and formal languages ; his earliest works in this field were probably Lambek (1958) and Lambek (1979) . He is noted, among other things, for the Lambek calculus , an effort to capture mathematical aspects of natural language syntax in logical form , and a work that has been very influential in computational linguistics , as well as for developing the connections between typed lambda calculus and cartesian closed categories (see Curry–Howard–Lambek correspondence ). His last works were on pregroup grammar . | https://en.wikipedia.org/wiki/Joachim_Lambek |
Joachim Maier (born 5 May 1955) is Emeritus Director at the Max Planck Institute for Solid State Research in Stuttgart (Germany) [ 1 ] and Scientific Member of the Max Planck Society.
Maier studied chemistry at Saarland University in Saarbrücken, made his Masters and PhD in Physical Chemistry there. He received his habilitation at the University of Tübingen . From 1988 to 1991 he was responsible for the activities on functional ceramics at the MPI for Metals Research in Stuttgart, and from 1988 to 1996 he taught defect chemistry at the Massachusetts Institute of Technology . Notwithstanding other prestigious offers, he decided in favor of the Max Planck Society. In 1991 he was appointed Scientific Member of the Max Planck Society, Director at the MPI for Solid State Research and Honorary Professor at the University of Stuttgart . He is the recipient of various prizes and a member of various national and international academies including German Academy of Sciences Leopoldina , [ 2 ] German Technical Academy Acatech, Academia Europaea, Academy of Science and Literature (Mainz, Germany), Fellow of the Royal Society of Chemistry, Fellow of the Electrochemical Society, IUPAC Fellow. Joachim Maier is Editor-in-Chief of Solid State Ionics and on the board of a number of scientific journals.
Maier's major research fields comprise physical chemistry of the solid state, thermodynamics and kinetics, defect chemistry and transport in solids, ionic and mixed conductors, boundary regions and electrochemistry. In this context energy transfer and storage are to the fore. Maier developed a scientific field nowadays termed nanoionics. Nanoionics refers to questions of ion transport, stoichiometry and reactivity in confined systems and is of equal significance for chemistry, physics and biology. In these fields Maier has authored/coauthored more than 800 publications in peer-reviewed journals. | https://en.wikipedia.org/wiki/Joachim_Maier |
The Joan & Joseph Birman Research Prize in Topology and Geometry is a prize given every other year by the Association for Women in Mathematics to an outstanding young female researcher in topology or geometry . The prize fund for the award was endowed by a donation in 2013 from Joan Birman and her husband, Joseph Birman , and first awarded in 2015. | https://en.wikipedia.org/wiki/Joan_&_Joseph_Birman_Research_Prize_in_Topology_and_Geometry |
Joan Cordiner FRSE FREng is a British chemical engineer . [ 1 ] [ 2 ] She is Vice President of the Institution of Chemical Engineers . [ 3 ]
She worked for Syngenta . She is a professor at University of Sheffield . [ 4 ] She researches process safety. [ 5 ] | https://en.wikipedia.org/wiki/Joan_Cordiner |
Joan Francés Fulcònis (in classical Occitan ; Johan Frances Fulconis , as written in his original edition) was a mathematician born in Lieusola (today and in French Isola ) ca 1520 and who lived in Nice . He is the author of La Cisterna Fulcronica , a treaty of arithmetics written in Occitan language and printed in Lyon in 1562.
The Cisterna has been thoroughly studied and edited by Roger Rocca and Rémy Gasiglia. Fulconis's references are Greek and Arab mathematicians. He was also inspired by Francés Pellos 's Compedion de l'Abaco (another arithmetical treaty, and also the first book printed in Occitan language – 1492 – ) though he does not directly mention it (we [ who? ] are sure, however, that he read it because some of his numerical examples are the same as in Pelos's work, which could not be a mere coincidence).
Both the Compendion and the Cisterna are written in Nissard dialect, but Fulconis only refers to his dialect as being Provençal dialect (a more generic word that includes Nissard's area). Whereas the Compedion is a more theoretical work, the Cisterna is very practically oriented to trade and gives many concrete examples that, today, represent for us [ who? ] an illustration of current life and trade relationships of his time. | https://en.wikipedia.org/wiki/Joan_Francés_Fulcònis |
Joanna Joy Bryson (born 1965) is professor at Hertie School in Berlin. She works on Artificial Intelligence , ethics and collaborative cognition. She has been a British citizen since 2007.
Bryson attended Glenbard North High School and graduated in 1982. She studied Behavioural Science at the University of Chicago , graduating with an AB in 1986. In 1991 she moved to the University of Edinburgh where she completed an MSc in Artificial Intelligence before an MPhil in Psychology. [ 1 ] Bryson moved to MIT to complete her PhD, earning a doctorate under Lynn Andrea Stein in 2001 for her thesis "Intelligence by Design: Principles of Modularity and Coordination for Engineering Complex Adaptive Agents". [ 2 ] In 1995 she worked for LEGO Futura in Boston, and then in 1998 she worked for LEGO Digital as an AI consultant with Kristinn R. Thórisson on cognitive architectures for autonomous LEGO characters in the Wizard Group. She completed a postdoctoral fellowship in Marc Hauser 's Primate Cognitive Neuroscience at the Harvard University in 2002. [ 3 ]
Bryson joined the Department of Computer Science at the University of Bath in 2002. At Bath, Bryson founded the Intelligent Systems research group. [ 4 ] In 2007 she joined the University of Nottingham as a visiting research fellow in the Methods and Data Institute. [ 5 ] During this time, she was a Hans Przibram Fellow at the Konrad Lorenz Institute for Evolution and Cognition . [ 5 ] She joined Oxford University as a visiting research fellow in 2010, working with Harvey Whitehouse on the impact of religion on societies. [ 5 ] [ 6 ]
In 2010 Bryson published Robots Should Be Slaves , which selected as a chapter in Yorick Wilks ' "Close Engagements with Artificial Companions: Key Social, Psychological, Ethical and Design Issues". [ 7 ] [ 8 ] She helped the EPSRC to define the Principles of Robotics in 2010. [ 9 ] In 2015 she was a Visiting Academic at the University of Princeton Center for Information Technology Policy , where she remained an affiliate through 2018. [ 10 ] She is focussed on "Standardizing Ethical Design for Artificial Intelligence and Autonomous Systems". [ 11 ] In 2020 she became Professor of Ethics and Technology at Hertie School of Governance in Berlin . [ 12 ]
Bryson's research has appeared in Science and on Reddit . [ 13 ] [ 14 ] She has consulted The Red Cross on autonomous weapons and contributed to an All Party Parliamentary Group on Artificial Intelligence. [ 15 ]
In 2022, Bryson published an article for Wired magazine titled "One Day, AI Will Seem as Human as Anyone. What Then?". In the article she discussed the current limits of and future of AI, how the general public define and think about AI, and how AI interacts with people via Language and touches upon the topics of natural language processing, ethics and Human-computer interaction. Bryson also dissusses the recent EU AI Act . [ 16 ]
In 2017, Bryson won an Outstanding Achievement award from Cognition X. [ 17 ] She regularly appears in national media, talking about human-robot relationships and the ethics of AI. [ 18 ] [ 19 ] | https://en.wikipedia.org/wiki/Joanna_Bryson |
Joanna Sigfred Fowler (born August 9, 1942) is a scientist emeritus at the U.S. Department of Energy 's Brookhaven National Laboratory in New York. She served as professor of psychiatry at Mount Sinai School of Medicine [ 1 ] and director of Brookhaven's Radiotracer Chemistry, Instrumentation and Biological Imaging Program. [ 2 ] Fowler studied the effect of disease, drugs, and aging on the human brain and radiotracers in brain chemistry. She has received many awards for her pioneering work, including the National Medal of Science .
Fowler was born in Miami, Florida , and attended the University of South Florida , where she received her bachelor's degree in chemistry in 1964. There, she worked in the laboratories of Jack Fernandez. Fowler received her Ph.D. in chemistry from the University of Colorado in 1967 and did her postdoctoral work at the University of East Anglia in England and at Brookhaven National Laboratory . Fowler worked at Brookhaven National Laboratory from 1969 until her retirement in January 2014. She is an emeritus professor in the chemistry department at Stony Brook University . [ 3 ]
She is married to Frank Fowler, an emeritus professor of organic chemistry at Stony Brook University.
Fowler's research has led to new fundamental knowledge, development of important scientific tools, and has broad impacts in the application of nuclear medicine to diagnostics and health. She has worked for much of her career developing radiotracers for brain imaging to understand the mechanisms underlying drug addiction. Most recently, she has been engaged in developing methods to understand the relationship between genes , brain chemistry, and behavior. [ 4 ]
In 1976, Fowler and her colleagues designed and synthesized a radioactively "tagged" form of sugar that is now used widely to study brain function and also to diagnose and plan treatment for cancer . She also developed another radiotracer , as these "tagged" molecules are called, that first showed that cocaine 's distribution in the human brain parallels its effects on behavior.
Fowler played a central role in the development of a fluorine -18-labeled glucose molecule (FDG) enabling human brain glucose metabolism to be measured noninvasively. This positron -emitting molecule, together with positron emission tomography (PET) imaging, has become a mainstay for brain-imaging studies in schizophrenia , aging and cancer .
Another of her major accomplishments was the development of the first radiotracers to map monoamine oxidase (MAO), a brain enzyme that regulates the levels of other nerve-cell communication chemicals and one of the two major enzymes involved in neurotransmitter regulation in the brain and peripheral organs. Using these radiotracers, she discovered that smokers have reduced levels of MAO in their brains and lungs. This may account for some of the behavioral and epidemiological features of smoking, such as the high rate of smoking in individuals with depression and drug addiction, two conditions involving poor nerve-cell communication, and has led to many studies on reduced MAO and smoking. [ 4 ]
Fowler holds eight patents for radiolabeling procedures. [ 1 ]
Fowler has published approximately 530 papers. [ 5 ] The following are a few of the most cited:
Fowler's scientific excellence and achievements have been recognized by prestigious awards, including the National Medal of Science , awarded in 2009 by President Obama. [ 6 ] In 2003, Fowler was elected to the National Academy of Sciences .
Her numerous other honors include: | https://en.wikipedia.org/wiki/Joanna_Fowler |
Joanna V. Clark is a geoscientist working for the NASA Johnson Space Center , where she is a collaborator on the Sample Analysis at Mars (SAM) and Mars Science Lab (MSL) science teams. Her research includes conducting laboratory experiments to understand better ground and mineral samples acquired by the curiosity rover on Mars. [ 1 ]
Clark has an undergraduate degree in geological sciences completed at The State University of New York at Geneseo in 2013, [ 1 ] a master's degree in geological sciences from The University of Alabama [ 1 ] completed in 2015, and a PhD in geological and earth sciences completed at The University of Houston in 2021. [ 2 ]
In 2019, Clark was awarded a two-year, $285,000 NASA grant to support the work of her thesis in which she studied the effect of temperature on silica formation to understand previous climate conditions on Mars better. To determine whether the planet once contained life, paleoclimatologists study clues left behind in rocks or, in this case, the oxygen composition of silica. Clark's research focused on performing laboratory experiments to form silica at subzero temperatures, which was then used to determine if water had previously been present on the planet. According to her advisor, Tom Lapen, it is rare for a graduate student to receive such major funding as these programs are highly competitive, with top researchers across the U.S. submitting hundreds of proposals. [ 3 ]
Joanna Clark became a full-time member of the Mars group at the NASA Johnson Space Center through the JETS II Contract, working under Jacobs Solutions Inc . [ 1 ] It is within this group that one of their primary science objectives is to assess the habitability of ancient and modern martian environments by using the Curiosity rover through a series of instruments and technologies that include: SAM , CheMin , APXS , ChemCam , DAN , REMS , RAD , MastCam & MAHLI . [ 4 ]
Clark is a payload uplink lead for the Curiosity rover , in which she delivers commands to collect samples for the SAM instrument to analyze. From there, results are sent back to Earth for her team to further assess past habitability and gather data to use for future exploration projects such as one day sending humans to Mars . [ 5 ]
One of Clark's projects for NASA included using mineralogical and chemical data from Curiosity to determine whether the Martian soil found from Rocknest could be used with a water-extraction device. This was accomplished by utilizing the SAM instrument and determining which chemical compounds were included in the Martian soil. From there, the Johnson Space Center replicated a simulant called JSC-Rocknest to run a variety of experiments on, which included heating it to different temperatures to determine its water re-absorption rate and determining its ability to be broken down into compounds needed for liveable conditions. Their findings include a variety of hopeful results necessary to further develop any new advancements for exploring Mars. Since the study, large quantities of JSC-Rocknest have been produced to continue with large-scale applications such as In-Situ Resource Utilization (ISRU) systems and component testing, ISRU plant growth studies, and ISRU habitat studies. [ 6 ] | https://en.wikipedia.org/wiki/Joanna_V._Clark |
In computing , a job is a unit of work or unit of execution (that performs said work). A component of a job (as a unit of work) is called a task or a step (if sequential, as in a job stream ). As a unit of execution, a job may be concretely identified with a single process , which may in turn have subprocesses ( child processes ; the process corresponding to the job being the parent process ) which perform the tasks or steps that comprise the work of the job; or with a process group ; or with an abstract reference to a process or process group, as in Unix job control .
Jobs can be started interactively, such as from a command line , or scheduled for non-interactive execution by a job scheduler , and then controlled via automatic or manual job control . Jobs that have finite input can complete, successfully or unsuccessfully, or fail to complete and eventually be terminated. By contrast, online processing such as by servers has open-ended input (they service requests as long as they run), and thus never complete, only stopping when terminated (sometimes called "canceled"): a server's job is never done.
The term "job" has a traditional meaning as "piece of work", from Middle English "jobbe of work", and is used as such in manufacturing, in the phrase " job production ", meaning "custom production", where it is contrasted with batch production (many items at once, one step at a time) and flow production (many items at once, all steps at the same time, by item). Note that these distinctions have become blurred in computing, where the oxymoronic term " batch job " is found, and used either for a one-off job or for a round of " batch processing " (same processing step applied to many items at once, originally punch cards ).
In this sense of "job", a programmable computer performs "jobs", as each one can be different from the last. The term "job" is also common in operations research , predating its use in computing, in such uses as job shop scheduling (see, for example Baker & Dzielinski (1960) and references thereof from throughout the 1950s, including several " System Research Department Reports " from IBM Research Center). This analogy is applied to computer systems, where the system resources are analogous to machines in a job shop , and the goal of scheduling is to minimize the total time from beginning to end ( makespan ). The term "job" for computing work dates to the mid 1950s, as in this use from 1955:
"The program for an individual job is then written, calling up these subroutines by name wherever required, thus avoiding rewriting them for individual problems". [ 1 ]
The term continued in occasional use, such as for the IBM 709 (1958), and in wider use by early 1960s, such as for the IBM 7090 , with widespread use from the Job Control Language of OS/360 (announced 1964). A standard early use of "job" is for compiling a program from source code, as this is a one-off task. The compiled program can then be run on batches of data. | https://en.wikipedia.org/wiki/Job_(computing) |
In computing , job control refers to the control of multiple tasks or jobs on a computer system , ensuring that they each have access to adequate resources to perform correctly, that competition for limited resources does not cause a deadlock where two or more jobs are unable to complete, resolving such situations where they do occur, and terminating jobs that, for any reason, are not performing as expected.
Job control has developed from the early days of computers where human operators were responsible for setting up, monitoring and controlling every job, to modern operating systems , which take on the bulk of the work of job control.
Even with a highly sophisticated scheduling system, some human intervention is desirable. Modern systems permit their users to stop and resume jobs, to execute them in the foreground (with the ability to interact with the user) or in the background. Unix-like systems follow this pattern .
It became obvious to the early computer developers that their fast machines spent most of the time idle because the single program they were executing had to wait while a slow peripheral device completed an essential operation such as reading or writing data; in modern terms, programs were I/O-bound , not compute-bound . Buffering only provided a partial solution; eventually an output buffer would occupy all available memory or an input buffer would be emptied by the program, and the system would be forced to wait for a relatively slow device to complete an operation.
A more general solution is multitasking . More than one running program, or process , is present in the computer at any given time. If a process is unable to continue, its context can be stored and the computer can start or resume the execution of another process. At first quite unsophisticated and relying on special programming techniques, multitasking soon became automated, and was usually performed by a special process called the scheduler , having the ability to interrupt and resume the execution of other processes. Typically a driver for a peripheral device suspends execution of the current process if the device is unable to complete an operation immediately, and the scheduler places the process on its queue of sleeping jobs. When the peripheral completed the operation the process is re-awakened. Similar suspension and resumption may also apply to inter-process communication , where processes have to communicate with one another in an asynchronous manner but may sometimes have to wait for a reply.
However this low-level scheduling has its drawbacks. A process that seldom needs to interact with peripherals or other processes would simply hog processor resource until it completed or was halted by manual intervention. The result, particularly for interactive systems running tasks that frequently interact with the outside world, is that the system is sluggish and slow to react in a timely manner. This problem is resolved by allocating a "timeslice" to each process, a period of uninterrupted execution after which the scheduler automatically puts it on the sleep queue. Process could be given different priorities, and the scheduler could then allocate varying shares of available execution time to each process on the basis of the assigned priorities.
This system of pre-emptive multitasking forms the basis of most modern job control systems.
While batch processing can run around the clock, with or without computer operators, [ 1 ] since the computer is much faster than a person, most decision-making occurs before the job even begins to run, and requires planning by the "programmer."
Although a computer operator may be present, batch processing is intended to mostly operate without human intervention. Therefore, many details must be included in the submitted instructions:
Early computer resident monitors and operating systems were relatively primitive and were not capable of sophisticated resource allocation. Typically such allocation decisions were made by the computer operator or the user who submitted a job. Batch processing was common, and interactive computer systems rare and expensive. Job control languages developed as primitive instructions, typically punched on cards at the head of a deck containing input data, requesting resources such as memory allocation, serial numbers or names of magnetic tape spools to be made available during execution, or assignment of filenames or devices to device numbers referenced by the job. A typical example of this kind of language, still in use on mainframes, is IBM 's Job Control Language (also known as JCL). Though the format of early JCLs was intended for punched card use, the format survived the transition to storage in computer files on disk.
Non-IBM mainframe batch systems had some form of job control language, whether called that or not; their syntax was completely different from IBM versions, but they usually provided similar capabilities. Interactive systems include " command languages "—command files (such as PCDOS ".bat" files) can be run non-interactively, but these usually do not provide as robust an environment for running unattended jobs as JCL. On some computer systems the job control language and the interactive command language may be different. For example, TSO on z/OS systems uses CLIST or Rexx as command languages along with JCL for batch work. On other systems these may be the same.
The Non-IBM JCL of what at one time was known as the BUNCH (Burroughs, Univac/Unisys, NCR, Control Data, Honeywell), except for Unisys , are part of the BANG [ 3 ] [ 4 ] that has been quieted.
As time sharing systems developed, interactive job control emerged. An end-user in a time sharing system could submit a job interactively from his remote terminal ( remote job entry ), communicate with the operators to warn them of special requirements, and query the system as to its progress. He could assign a priority to the job, and terminate (kill) it if desired. He could also, naturally, run a job in the foreground, where he would be able to communicate directly with the executing program. During interactive execution he could interrupt the job and let it continue in the background or kill it. This development of interactive computing in a multitasking environment led to the development of the modern shell .
The ability to not have to specify part or all of the information about a file or device to be used by a given program is called device independence .
Pre-emptive multitasking with job control assures that a system operates in a timely manner most of the time . In some environments (for instance, operating expensive or dangerous machinery), a strong design constraint of the system is the delivery of timely results in all circumstances. In such circumstances, job control is more complex and the role of scheduling is more important.
Since real-time systems do event-driven scheduling for all real-time operations, "the sequence of these real-time operations is not under the immediate control of a computer operator or programmer." [ 5 ]
However, a system may have the ability to interleave real-time and other, less time-critical tasks, where the dividing line might for example be response required within one tenth of a second. [ 5 ] : p.1 In the case of the Xerox RBM (Real-time/Batch Monitor) systems, [ 6 ] [ 7 ] [ 8 ] for example, two other capabilities existed: [ 5 ] : p.2 | https://en.wikipedia.org/wiki/Job_control_(computing) |
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