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Alinea (2 species)
Aspronema (2 species)
Brasiliscincus (3 species)
Capitellum (3 species)
Chioninia (7 species)
Copeoglossum (5 species)
Dasia (10 species)
Eumecia (2 species)
Eutropis (48 species)
Exila (1 species)
Heremites (3 species)
Lubuya (1 species)
Mabuya (9 species)
Manciola (1 species)
Maracaib... | Skink | Wikipedia | 199 | 323825 | https://en.wikipedia.org/wiki/Skink | Biology and health sciences | Reptiles | null |
Anomalopus (4 species)
Calorodius (1 species)
Calyptotis (4 species)
Coeranoscincus (2 species)
Coggeria (1 species)
Concinnia (7 species)
Ctenotus (103 species)
Eremiascincus (15 species)
Eulamprus (5 species)
Fojia (1 species)
Glaphyromorphus (11 species)
Gnypetoscincus (1 species)
Hemiergis (7 species)
... | Skink | Wikipedia | 347 | 323825 | https://en.wikipedia.org/wiki/Skink | Biology and health sciences | Reptiles | null |
Amphiglossus (2 species)
Ateuchosaurus (2 species)
Barkudia (2 species)
Brachymeles (42 species)
Brachyseps (8 species)
Chalcides (32 species)
Chalcidoseps (1 species)
Eumeces (6 species)
Eurylepis (2 species)
Feylinia (6 species)
Flexiseps (15 species)
Gongylomorphus (3 species)
Grandidierina (4 species)
... | Skink | Wikipedia | 274 | 323825 | https://en.wikipedia.org/wiki/Skink | Biology and health sciences | Reptiles | null |
Subsistence agriculture occurs when farmers grow crops on smallholdings to meet the needs of themselves and their families. Subsistence agriculturalists target farm output for survival and for mostly local requirements. Planting decisions occur principally with an eye toward what the family will need during the coming ... | Subsistence agriculture | Wikipedia | 440 | 323964 | https://en.wikipedia.org/wiki/Subsistence%20agriculture | Technology | Forms | null |
Contemporary practices
Subsistence farming continues today in large parts of rural Africa, and parts of Asia and Latin America. In 2015, about 2 billion people (slightly more than 25% of the world's population) in 500 million households living in rural areas of developing nations survive as "smallholder" farmers, work... | Subsistence agriculture | Wikipedia | 301 | 323964 | https://en.wikipedia.org/wiki/Subsistence%20agriculture | Technology | Forms | null |
Adaptation to global warming
Most subsistence agriculture is practiced in developing countries located in tropical climates. Effects on crop production brought about by climate change will be more intense in these regions as extreme temperatures are linked to lower crop yields. Farmers have been forced to respond to i... | Subsistence agriculture | Wikipedia | 339 | 323964 | https://en.wikipedia.org/wiki/Subsistence%20agriculture | Technology | Forms | null |
In this type of farming, a patch of forest land is cleared by a combination of felling (chopping down) and burning, and crops are grown. After two–three years the fertility of the soil begins to decline, the land is abandoned and the farmer moves to clear a fresh piece of land elsewhere in the forest as the process con... | Subsistence agriculture | Wikipedia | 402 | 323964 | https://en.wikipedia.org/wiki/Subsistence%20agriculture | Technology | Forms | null |
Nomadic herding
In this type of farming people migrate along with their animals from one place to another in search of fodder for their animals. Generally they rear cattle, sheep, goats, camels and/or yaks for milk, skin, meat and wool. This way of life is common in parts of central and western Asia, India, east and so... | Subsistence agriculture | Wikipedia | 506 | 323964 | https://en.wikipedia.org/wiki/Subsistence%20agriculture | Technology | Forms | null |
Agriculture is more successful than non-agricultural jobs in combating poverty in countries with a larger population of people without education or who are unskilled. However, there are levels of poverty to be aware of to target agriculture towards the right audience. Agriculture is better at reducing poverty in those ... | Subsistence agriculture | Wikipedia | 133 | 323964 | https://en.wikipedia.org/wiki/Subsistence%20agriculture | Technology | Forms | null |
The Eurasian collared dove (Streptopelia decaocto), often simply just collared dove, is a dove species native to Europe, Asia, and northern Africa. It has also been introduced to Japan, North and Central America, and the islands in the Caribbean.
Taxonomy
The Hungarian naturalist Imre Frivaldszky first described the ... | Eurasian collared dove | Wikipedia | 348 | 323988 | https://en.wikipedia.org/wiki/Eurasian%20collared%20dove | Biology and health sciences | Columbimorphae | Animals |
Etymology
The generic name is from the Ancient Greek streptos meaning "collar" and peleia meaning "dove". The specific epithet, decaocto, is Greek for "eighteen". The association of the dove with the number eighteen has its roots in a Greek myth. A maid who worked hard for little money was unhappy that she was only pai... | Eurasian collared dove | Wikipedia | 249 | 323988 | https://en.wikipedia.org/wiki/Eurasian%20collared%20dove | Biology and health sciences | Columbimorphae | Animals |
The Eurasian collared dove is a medium-sized dove, distinctly smaller than the wood pigeon, similar in length to a rock dove but slimmer and longer-tailed, and slightly larger than the related European turtle dove, with an average length of from tip of beak to tip of tail, with a wingspan of , and a weight of . It is ... | Eurasian collared dove | Wikipedia | 383 | 323988 | https://en.wikipedia.org/wiki/Eurasian%20collared%20dove | Biology and health sciences | Columbimorphae | Animals |
The Eurasian collared dove is not migratory, but is strongly dispersive. Over the last century, it has been one of the great colonisers of the bird world, travelling far beyond its native range to colonise colder countries, becoming a permanent resident in several of them. Its original range at the end of the 19th cent... | Eurasian collared dove | Wikipedia | 483 | 323988 | https://en.wikipedia.org/wiki/Eurasian%20collared%20dove | Biology and health sciences | Columbimorphae | Animals |
Population growth has ceased in areas where the species has long been established, such as Florida, and in these regions, recent observations suggest the population is in decline. The population is still growing exponentially in areas of more recent introduction; up to 2015, the Eurasian collared dove experienced a gre... | Eurasian collared dove | Wikipedia | 461 | 323988 | https://en.wikipedia.org/wiki/Eurasian%20collared%20dove | Biology and health sciences | Columbimorphae | Animals |
Food and feeding
The Eurasian collared dove is not wary and often feeds very close to human habitation, including visiting bird tables; the largest populations are typically found around farms where spilt grain is frequent around grain stores or where livestock are fed. It is a gregarious species and sizeable winter fl... | Eurasian collared dove | Wikipedia | 106 | 323988 | https://en.wikipedia.org/wiki/Eurasian%20collared%20dove | Biology and health sciences | Columbimorphae | Animals |
A cash crop, also called profit crop, is an agricultural crop which is grown to sell for profit. It is typically purchased by parties separate from a farm. The term is used to differentiate a marketed crop from a staple crop ("subsistence crop") in subsistence agriculture, which is one fed to the producer's own livesto... | Cash crop | Wikipedia | 478 | 323990 | https://en.wikipedia.org/wiki/Cash%20crop | Technology | Basics_2 | null |
Temperate
Cash crops grown in regions with a temperate climate include many cereals (wheat, rye, corn, barley, oats), oil-yielding crops (e.g. grapeseed, mustard seeds), vegetables (e.g. potatoes), lumber yielding trees (e.g. Spruce, Pines, Firs), tree fruit or top fruit (e.g. apples, cherries) and soft fruit (e.g. str... | Cash crop | Wikipedia | 502 | 323990 | https://en.wikipedia.org/wiki/Cash%20crop | Technology | Basics_2 | null |
Africa has realized significant growth in biofuel plantations, many of which are on lands which were purchased by British companies. Jatropha curcas is a cash crop grown for biofuel production in Africa. Some have criticized the practice of raising non-food plants for export while Africa has problems with hunger and fo... | Cash crop | Wikipedia | 486 | 323990 | https://en.wikipedia.org/wiki/Cash%20crop | Technology | Basics_2 | null |
Sustainability of cash crops
Approximately 70% of the world's food is produced by 500 million smallholder farmers. For their livelihood they depend on the production of cash crops, basic commodities that are hard to differentiate in the market. The great majority (80%) of the world's farms measure 2 hectares or less. T... | Cash crop | Wikipedia | 433 | 323990 | https://en.wikipedia.org/wiki/Cash%20crop | Technology | Basics_2 | null |
In computer programming, a parameter or a formal argument is a special kind of variable used in a subroutine to refer to one of the pieces of data provided as input to the subroutine. These pieces of data are the values of the arguments (often called actual arguments or actual parameters) with which the subroutine is ... | Parameter (computer programming) | Wikipedia | 507 | 324375 | https://en.wikipedia.org/wiki/Parameter%20%28computer%20programming%29 | Technology | Software development: General | null |
After the function has been defined, it can be invoked as follows:
SalesTax(10.00);
In this example, the function has been invoked with the argument 10.00. When this happens, 10.00 will be assigned to price, and the function begins calculating its result. The steps for producing the result are specified below, enclose... | Parameter (computer programming) | Wikipedia | 468 | 324375 | https://en.wikipedia.org/wiki/Parameter%20%28computer%20programming%29 | Technology | Software development: General | null |
A parameter is an intrinsic property of the procedure, included in its definition. For example, in many languages, a procedure to add two supplied integers together and calculate the sum would need two parameters, one for each integer. In general, a procedure may be defined with any number of parameters, or no paramete... | Parameter (computer programming) | Wikipedia | 475 | 324375 | https://en.wikipedia.org/wiki/Parameter%20%28computer%20programming%29 | Technology | Software development: General | null |
The code which calls the Sum function might look like this:
int value1 = 40;
int value2 = 2;
int sum_value = Sum(value1, value2);
The variables value1 and value2 are initialized with values. value1 and value2 are both arguments to the sum function in this context.
At runtime, the values assigned to these variables are... | Parameter (computer programming) | Wikipedia | 468 | 324375 | https://en.wikipedia.org/wiki/Parameter%20%28computer%20programming%29 | Technology | Software development: General | null |
When a class becomes a client to HASH_TABLE, the formal generic parameters are substituted with actual generic parameters in a generic derivation. In the following attribute declaration, my_dictionary is to be used as a character string based dictionary. As such, both data and key formal generic parameters are substitu... | Parameter (computer programming) | Wikipedia | 481 | 324375 | https://en.wikipedia.org/wiki/Parameter%20%28computer%20programming%29 | Technology | Software development: General | null |
Variable-length parameter lists
Some languages allow subroutines to be defined to accept a variable number of arguments. For such languages, the subroutines must iterate through the list of arguments.
PowerShell example:
function marty {
$args | foreach { "back to the year $_" }
}
PS > marty 1985
back to the yea... | Parameter (computer programming) | Wikipedia | 434 | 324375 | https://en.wikipedia.org/wiki/Parameter%20%28computer%20programming%29 | Technology | Software development: General | null |
Output parameters
An output parameter, also known as an out parameter or return parameter, is a parameter used for output, rather than the more usual use for input. Using call by reference parameters, or call by value parameters where the value is a reference, as output parameters is an idiom in some languages, notably... | Parameter (computer programming) | Wikipedia | 491 | 324375 | https://en.wikipedia.org/wiki/Parameter%20%28computer%20programming%29 | Technology | Software development: General | null |
Syntactically, parameter mode is generally indicated with a keyword in the function declaration, such as void f(out int x) in C#. Conventionally output parameters are often put at the end of the parameter list to clearly distinguish them, though this is not always followed. TScript uses a different approach, where in t... | Parameter (computer programming) | Wikipedia | 461 | 324375 | https://en.wikipedia.org/wiki/Parameter%20%28computer%20programming%29 | Technology | Software development: General | null |
Use
The primary use of output parameters is to return multiple values from a function, while the use of input/output parameters is to modify state using parameter passing (rather than by shared environment, as in global variables). An important use of returning multiple values is to solve the semipredicate problem of r... | Parameter (computer programming) | Wikipedia | 404 | 324375 | https://en.wikipedia.org/wiki/Parameter%20%28computer%20programming%29 | Technology | Software development: General | null |
Output and input/output parameters prevent function composition, since the output is stored in variables, rather than in the value of an expression. Thus one must initially declare a variable, and then each step of a chain of functions must be a separate statement. For example, in C++ the following function composition... | Parameter (computer programming) | Wikipedia | 478 | 324375 | https://en.wikipedia.org/wiki/Parameter%20%28computer%20programming%29 | Technology | Software development: General | null |
In object-oriented languages, instead of using input/output parameters, one can often use call by sharing, passing a reference to an object and then mutating the object, though not changing which object the variable refers to. | Parameter (computer programming) | Wikipedia | 46 | 324375 | https://en.wikipedia.org/wiki/Parameter%20%28computer%20programming%29 | Technology | Software development: General | null |
Mortar is a workable paste which hardens to bind building blocks such as stones, bricks, and concrete masonry units, to fill and seal the irregular gaps between them, spread the weight of them evenly, and sometimes to add decorative colours or patterns to masonry walls. In its broadest sense, mortar includes pitch, as... | Mortar (masonry) | Wikipedia | 501 | 324498 | https://en.wikipedia.org/wiki/Mortar%20%28masonry%29 | Technology | Building materials | null |
Gypsum cement that was "light grey and contained sand, clay, traces of calcium carbonate, and a high percentage of lime" was used in the construction of wells, drains, and on the exteriors of "important looking buildings." Bitumen mortar was also used at a lower-frequency, including in the Great Bath at Mohenjo-daro.
... | Mortar (masonry) | Wikipedia | 506 | 324498 | https://en.wikipedia.org/wiki/Mortar%20%28masonry%29 | Technology | Building materials | null |
Ordinary Portland cement mortar, commonly known as OPC mortar or just cement mortar, is created by mixing powdered ordinary Portland cement, fine aggregate and water.
It was invented in 1794 by Joseph Aspdin and patented on 18 December 1824, largely as a result of efforts to develop stronger mortars. It was made popul... | Mortar (masonry) | Wikipedia | 454 | 324498 | https://en.wikipedia.org/wiki/Mortar%20%28masonry%29 | Technology | Building materials | null |
The setting speed can be increased by using impure limestone in the kiln, to form a hydraulic lime that will set on contact with water. Such a lime must be stored as a dry powder. Alternatively, a pozzolanic material such as calcined clay or brick dust may be added to the mortar mix. Addition of a pozzolanic material ... | Mortar (masonry) | Wikipedia | 497 | 324498 | https://en.wikipedia.org/wiki/Mortar%20%28masonry%29 | Technology | Building materials | null |
Radiocarbon dating
As the mortar hardens, the current atmosphere is encased in the mortar and thus provides a sample for analysis. Various factors affect the sample and raise the margin of error for the analysis.
Radiocarbon dating of mortar began as early as the 1960s, soon after the method was established (Delibrias ... | Mortar (masonry) | Wikipedia | 224 | 324498 | https://en.wikipedia.org/wiki/Mortar%20%28masonry%29 | Technology | Building materials | null |
A mortar today is usually a simple, lightweight, man-portable, muzzle-loaded cannon, consisting of a smooth-bore (although some models use a rifled barrel) metal tube fixed to a base plate (to spread out the recoil) with a lightweight bipod mount and a sight. Mortars are typically used as indirect fire weapons for clos... | Mortar (weapon) | Wikipedia | 337 | 324499 | https://en.wikipedia.org/wiki/Mortar%20%28weapon%29 | Technology | Artillery and siege | null |
Early mortars, such as the Pumhart von Steyr, were large and heavy and could not be easily transported. Simply made, these weapons were no more than iron bowls reminiscent of the kitchen and apothecary mortars whence they drew their name. An early transportable mortar was invented by Baron Menno van Coehoorn in 1701. T... | Mortar (weapon) | Wikipedia | 467 | 324499 | https://en.wikipedia.org/wiki/Mortar%20%28weapon%29 | Technology | Artillery and siege | null |
It was not until the Stokes mortar was devised by Sir Wilfred Stokes in 1915 during the First World War that the modern mortar transportable by one person was born. In the conditions of trench warfare, there was a great need for a versatile and easily portable weapon that could be manned by troops under cover in the tr... | Mortar (weapon) | Wikipedia | 410 | 324499 | https://en.wikipedia.org/wiki/Mortar%20%28weapon%29 | Technology | Artillery and siege | null |
Mortar carriers are vehicles which carry a mortar as a primary weapon. Numerous vehicles have been used to mount mortars, from improvised civilian trucks used by insurgents, to modified infantry fighting vehicles, such as variants of the M3 half-track and M113 armored personnel carrier, to vehicles specifically intende... | Mortar (weapon) | Wikipedia | 181 | 324499 | https://en.wikipedia.org/wiki/Mortar%20%28weapon%29 | Technology | Artillery and siege | null |
Gun-mortars are breech-loaded mortars usually equipped with a hydraulic recoil mechanism, and sometimes equipped with an autoloader. They are usually mounted on an armoured vehicle and are capable of both direct fire and indirect fire. The archetypes are the Brandt Mle CM60A1 and Brandt 60 mm LR, which combine features... | Mortar (weapon) | Wikipedia | 383 | 324499 | https://en.wikipedia.org/wiki/Mortar%20%28weapon%29 | Technology | Artillery and siege | null |
A spigot mortar consists mainly of a solid rod or spigot, onto which a hollow tube in the projectile fits—inverting the normal tube-mortar arrangement. At the top of the tube in the projectile, a cavity contains propellant, such as cordite. There is usually a trigger mechanism built into the base of the spigot, with a ... | Mortar (weapon) | Wikipedia | 388 | 324499 | https://en.wikipedia.org/wiki/Mortar%20%28weapon%29 | Technology | Artillery and siege | null |
Spigot mortars generally fell out of favour after World War II and were replaced by smaller conventional mortars. Military applications of spigot mortars include:
The petard mortar used on the Churchill AVRE by Britain in World War II.
The Type 98 mortar used by Japan in World War II to some psychological effect in... | Mortar (weapon) | Wikipedia | 476 | 324499 | https://en.wikipedia.org/wiki/Mortar%20%28weapon%29 | Technology | Artillery and siege | null |
The Pasilan 2000, the improved version, has been developed with characteristics similar to a rocket launcher. The Pasilan 2000 was a heavy mortar fired from a mobile launcher mounted on a tractor. The shell does not emit constant muzzle flares like artillery or MBRL. This is ideal for LTTE's camouflage and conceals att... | Mortar (weapon) | Wikipedia | 502 | 324499 | https://en.wikipedia.org/wiki/Mortar%20%28weapon%29 | Technology | Artillery and siege | null |
Operators may fire spin-stabilised rounds from either a smoothbore or a rifled barrel. Rifled mortars are more accurate but slower to load. Since mortars are generally muzzle-loaded, mortar bombs for rifled barrels usually have a pre-engraved band, called an obturator, that engages with the rifling of the barrel. Excep... | Mortar (weapon) | Wikipedia | 448 | 324499 | https://en.wikipedia.org/wiki/Mortar%20%28weapon%29 | Technology | Artillery and siege | null |
The GMM 120 (Guided Mortar Munition 120; known as Patzmi; also referred to as Morty) is a GPS and/or laser-guided mortar munition, which was developed by Israel Military Industries. Another Israeli guided mortar is Iron Sting, developed by Elbit. The Russian KM-8 Gran is also laser-guided.
Compared to long range artil... | Mortar (weapon) | Wikipedia | 395 | 324499 | https://en.wikipedia.org/wiki/Mortar%20%28weapon%29 | Technology | Artillery and siege | null |
Fin-stabilised mortar bombs do not have to withstand the rotational forces placed upon them by rifling or greater pressures, and can therefore carry a higher payload in a thinner skin than rifled artillery ammunition. Because of the difference in available volume, a smooth-bore mortar of a given diameter will have a gr... | Mortar (weapon) | Wikipedia | 347 | 324499 | https://en.wikipedia.org/wiki/Mortar%20%28weapon%29 | Technology | Artillery and siege | null |
The metatarsal bones or metatarsus (: metatarsi) are a group of five long bones in the midfoot, located between the tarsal bones (which form the heel and the ankle) and the phalanges (toes). Lacking individual names, the metatarsal bones are numbered from the medial side (the side of the great toe): the first, second, ... | Metatarsal bones | Wikipedia | 506 | 324681 | https://en.wikipedia.org/wiki/Metatarsal%20bones | Biology and health sciences | Skeletal system | Biology |
The first metatarsal articulates with the medial cuneiform, and to a small extent to the intermediate cuneiform.
the second with all three cuneiforms.
the third with the lateral cuneiform.
the fourth with the lateral cuneiform and the cuboid.
The fifth with the cuboid.
Muscle attachments
Clinical significance
In... | Metatarsal bones | Wikipedia | 266 | 324681 | https://en.wikipedia.org/wiki/Metatarsal%20bones | Biology and health sciences | Skeletal system | Biology |
In human anatomy, the metacarpal bones or metacarpus, also known as the "palm bones", are the appendicular bones that form the intermediate part of the hand between the phalanges (fingers) and the carpal bones (wrist bones), which articulate with the forearm. The metacarpal bones are homologous to the metatarsal bones... | Metacarpal bones | Wikipedia | 487 | 324697 | https://en.wikipedia.org/wiki/Metacarpal%20bones | Biology and health sciences | Skeletal system | Biology |
Base
The base (basis) or carpal extremity is of a cuboidal form, and broader behind than in front. It articulates with the carpal bones and with the adjoining metacarpal bones while its dorsal and volar surfaces are rough, for the attachment of ligaments.
Head
The head (caput) or digital extremity presents an oblong... | Metacarpal bones | Wikipedia | 503 | 324697 | https://en.wikipedia.org/wiki/Metacarpal%20bones | Biology and health sciences | Skeletal system | Biology |
Opponens digiti minimi: Inserts on the medial surface of metacarpal V; Flexes metacarpal V at carpometacarpal joint when little finger is moved into opposition with tip of thumb; deepens palm of hand.
Clinical significance
Congenital disorders
The fourth and fifth metacarpal bones are commonly "blunted" or shortened... | Metacarpal bones | Wikipedia | 403 | 324697 | https://en.wikipedia.org/wiki/Metacarpal%20bones | Biology and health sciences | Skeletal system | Biology |
Etymology
The Greek physician Galen used to refer to the as μετακάρπιον. The Latin form more truly resembles its Ancient Greek predecessor μετακάρπιον than metacarpus. Meta– is Greek for beyond and carpal from Ancient Greek καρπός (, “wrist”).
In anatomic Latin, adjectives like , , , , and can be found. The form ... | Metacarpal bones | Wikipedia | 159 | 324697 | https://en.wikipedia.org/wiki/Metacarpal%20bones | Biology and health sciences | Skeletal system | Biology |
In mathematics, the modular group is the projective special linear group of matrices with integer coefficients and determinant 1. The matrices and are identified. The modular group acts on the upper-half of the complex plane by fractional linear transformations, and the name "modular group" comes from the relation... | Modular group | Wikipedia | 503 | 325019 | https://en.wikipedia.org/wiki/Modular%20group | Mathematics | Abstract algebra | null |
is a lattice of parallelograms on the plane. A different pair of vectors and will generate exactly the same lattice if and only if
for some matrix in . It is for this reason that doubly periodic functions, such as elliptic functions, possess a modular group symmetry.
The action of the modular group on the rational... | Modular group | Wikipedia | 499 | 325019 | https://en.wikipedia.org/wiki/Modular%20group | Mathematics | Abstract algebra | null |
The braid group is the universal central extension of the modular group, with these sitting as lattices inside the (topological) universal covering group . Further, the modular group has a trivial center, and thus the modular group is isomorphic to the quotient group of modulo its center; equivalently, to the group o... | Modular group | Wikipedia | 464 | 325019 | https://en.wikipedia.org/wiki/Modular%20group | Mathematics | Abstract algebra | null |
There is a strong connection between the modular group and elliptic curves. Each point in the upper half-plane gives an elliptic curve, namely the quotient of by the lattice generated by 1 and .
Two points in the upper half-plane give isomorphic elliptic curves if and only if they are related by a transformation in... | Modular group | Wikipedia | 504 | 325019 | https://en.wikipedia.org/wiki/Modular%20group | Mathematics | Abstract algebra | null |
Being the kernel of a homomorphism is a normal subgroup of the modular group . The group is given as the set of all modular transformations
for which and .
It is easy to show that the trace of a matrix representing an element of cannot be −1, 0, or 1, so these subgroups are torsion-free groups. (There are other t... | Modular group | Wikipedia | 509 | 325019 | https://en.wikipedia.org/wiki/Modular%20group | Mathematics | Abstract algebra | null |
where . For small values of , one has:
The modular group is isomorphic to and they share properties and applications – for example, just as one has the free product of cyclic groups
more generally one has
which corresponds to the triangle group . There is similarly a notion of principal congruence subgroups associ... | Modular group | Wikipedia | 140 | 325019 | https://en.wikipedia.org/wiki/Modular%20group | Mathematics | Abstract algebra | null |
Historical geology or palaeogeology is a discipline that uses the principles and methods of geology to reconstruct the geological history of Earth. Historical geology examines the vastness of geologic time, measured in billions of years, and investigates changes in the Earth, gradual and sudden, over this deep time. It... | Historical geology | Wikipedia | 498 | 325030 | https://en.wikipedia.org/wiki/Historical%20geology | Physical sciences | Basics | Earth science |
Economic geology, the search for and extraction of fuel and raw materials, is heavily dependent on an understanding of the geological history of an area. Environmental geology, which examines the impacts of natural hazards such as earthquakes and volcanism, must rely on a detailed knowledge of geological history.
Meth... | Historical geology | Wikipedia | 446 | 325030 | https://en.wikipedia.org/wiki/Historical%20geology | Physical sciences | Basics | Earth science |
Tidal power or tidal energy is harnessed by converting energy from tides into useful forms of power, mainly electricity using various methods.
Although not yet widely used, tidal energy has the potential for future electricity generation. Tides are more predictable than the wind and the sun. Among sources of renewabl... | Tidal power | Wikipedia | 490 | 325060 | https://en.wikipedia.org/wiki/Tidal%20power | Technology | Power generation | null |
Tidal power is the only technology that draws on energy inherent in the orbital characteristics of the Earth–Moon system, and to a lesser extent in the Earth–Sun system. Other natural energies exploited by human technology originate directly or indirectly from the Sun, including fossil fuel, conventional hydroelectric,... | Tidal power | Wikipedia | 488 | 325060 | https://en.wikipedia.org/wiki/Tidal%20power | Technology | Power generation | null |
Tidal barrages use potential energy in the difference in height (or hydraulic head) between high and low tides. When using tidal barrages to generate power, the potential energy from a tide is seized through the strategic placement of specialized dams. When the sea level rises and the tide begins to come in, the tempo... | Tidal power | Wikipedia | 432 | 325060 | https://en.wikipedia.org/wiki/Tidal%20power | Technology | Power generation | null |
US and Canadian studies in the 20th century
The first study of large scale tidal power plants was by the US Federal Power Commission in 1924. If built, power plants would have been located in the northern border area of the US state of Maine and the southeastern border area of the Canadian province of New Brunswick, w... | Tidal power | Wikipedia | 364 | 325060 | https://en.wikipedia.org/wiki/Tidal%20power | Technology | Power generation | null |
US studies in the 21st century
The Snohomish PUD, a public utility district located primarily in Snohomish County, Washington State, began a tidal energy project in 2007. In April 2009 the PUD selected OpenHydro, a company based in Ireland, to develop turbines and equipment for eventual installation. The project as in... | Tidal power | Wikipedia | 416 | 325060 | https://en.wikipedia.org/wiki/Tidal%20power | Technology | Power generation | null |
Tidal power development in the UK
The world's first marine energy test facility was established in 2003 to start the development of the wave and tidal energy industry in the UK. Based in Orkney, Scotland, the European Marine Energy Centre (EMEC) has supported the deployment of more wave and tidal energy devices than a... | Tidal power | Wikipedia | 240 | 325060 | https://en.wikipedia.org/wiki/Tidal%20power | Technology | Power generation | null |
The Rance tidal power plant built over a period of six years from 1960 to 1966 at La Rance, France. It has 240 MW installed capacity.
254 MW Sihwa Lake Tidal Power Plant in South Korea is the largest tidal power installation in the world. Construction was completed in 2011.
The Jiangxia Tidal Power Station, south of ... | Tidal power | Wikipedia | 460 | 325060 | https://en.wikipedia.org/wiki/Tidal%20power | Technology | Power generation | null |
The Indian state of Gujarat was planning to host South Asia's first commercial-scale tidal power station. The company Atlantis Resources planned to install a 50 MW tidal farm in the Gulf of Kutch on India's west coast, with construction planned to start 2012, later withdrawn due to high costs.
Ocean Renewable Power Co... | Tidal power | Wikipedia | 403 | 325060 | https://en.wikipedia.org/wiki/Tidal%20power | Technology | Power generation | null |
Issues and challenges
Environmental concerns
Tidal power can affect marine life. The turbines' rotating blades can accidentally kill swimming sea life. Projects such as the one in Strangford include a safety mechanism that turns off the turbine when marine animals approach. However, this feature causes a major loss i... | Tidal power | Wikipedia | 413 | 325060 | https://en.wikipedia.org/wiki/Tidal%20power | Technology | Power generation | null |
Tidal barrage
Installing a barrage may change the shoreline within the bay or estuary, affecting a large ecosystem that depends on tidal flats. Inhibiting the flow of water in and out of the bay, there may also be less flushing of the bay or estuary, causing additional turbidity (suspended solids) and less saltwater, ... | Tidal power | Wikipedia | 440 | 325060 | https://en.wikipedia.org/wiki/Tidal%20power | Technology | Power generation | null |
Cost
Tidal energy has a high initial cost, which may be one of the reasons why it is not a popular source of renewable energy, although research has shown that the public is willing to pay for and support research and development of tidal energy devices. The methods of generating electricity from tidal energy are rela... | Tidal power | Wikipedia | 288 | 325060 | https://en.wikipedia.org/wiki/Tidal%20power | Technology | Power generation | null |
Domain theory is a branch of mathematics that studies special kinds of partially ordered sets (posets) commonly called domains. Consequently, domain theory can be considered as a branch of order theory. The field has major applications in computer science, where it is used to specify denotational semantics, especially ... | Domain theory | Wikipedia | 467 | 325077 | https://en.wikipedia.org/wiki/Domain%20theory | Mathematics | Order theory | null |
The important step to finding a model for the lambda calculus is to consider only those functions (on such a partially ordered set) that are guaranteed to have least fixed points. The set of these functions, together with an appropriate ordering, is again a "domain" in the sense of the theory. But the restriction to a ... | Domain theory | Wikipedia | 455 | 325077 | https://en.wikipedia.org/wiki/Domain%20theory | Mathematics | Order theory | null |
A concept that plays an important role in the theory is that of a directed subset of a domain; a directed subset is a non-empty subset of the order in which any two elements have an upper bound that is an element of this subset. In view of our intuition about domains, this means that any two pieces of information withi... | Domain theory | Wikipedia | 421 | 325077 | https://en.wikipedia.org/wiki/Domain%20theory | Mathematics | Order theory | null |
Computations and domains
Now that we have some basic formal descriptions of what a domain of computation should be, we can turn to the computations themselves. Clearly, these have to be functions, taking inputs from some computational domain and returning outputs in some (possibly different) domain. However, one woul... | Domain theory | Wikipedia | 459 | 325077 | https://en.wikipedia.org/wiki/Domain%20theory | Mathematics | Order theory | null |
Way-below relation
A more elaborate approach leads to the definition of the so-called order of approximation, which is more suggestively also called the way-below relation. An element x is way below an element y, if, for every directed set D with supremum such that
,
there is some element d in D such that
.
Then on... | Domain theory | Wikipedia | 409 | 325077 | https://en.wikipedia.org/wiki/Domain%20theory | Mathematics | Order theory | null |
More generally, we would like to restrict to a certain subset of elements as being sufficient for getting all other elements as least upper bounds. Hence, one defines a base of a poset P as being a subset B of P, such that, for each x in P, the set of elements in B that are way below x contains a directed set with supr... | Domain theory | Wikipedia | 457 | 325077 | https://en.wikipedia.org/wiki/Domain%20theory | Mathematics | Order theory | null |
All of these classes of orders can be cast into various categories of dcpos, using functions that are monotone, Scott-continuous, or even more specialized as morphisms. Finally, note that the term domain itself is not exact and thus is only used as an abbreviation when a formal definition has been given before or when ... | Domain theory | Wikipedia | 196 | 325077 | https://en.wikipedia.org/wiki/Domain%20theory | Mathematics | Order theory | null |
Pollination management is the horticultural practices that accomplish or enhance pollination of a crop, to improve yield or quality, by understanding of the particular crop's pollination needs, and by knowledgeable management of pollenizers, pollinators, and pollination conditions.
While people think first of the Euro... | Pollination management | Wikipedia | 373 | 325663 | https://en.wikipedia.org/wiki/Pollination%20management | Technology | Horticulture | null |
Crops that traditionally have had managed pollination include apple, almonds, pears, some plum and cherry varieties, blueberries, cranberries, cucumbers, cantaloupe, watermelon, alfalfa seeds, onion seeds, and many others. Some crops that have traditionally depended entirely on chance pollination by wild pollinators ne... | Pollination management | Wikipedia | 488 | 325663 | https://en.wikipedia.org/wiki/Pollination%20management | Technology | Horticulture | null |
It is estimated that about one hive per acre will sufficiently pollinate watermelons. In the 1950s when the woods were full of wild bee trees, and beehives were normally kept on most South Carolina farms, a farmer who grew ten acres (4 ha) of watermelons would be a large grower and probably had all the pollination need... | Pollination management | Wikipedia | 475 | 325663 | https://en.wikipedia.org/wiki/Pollination%20management | Technology | Horticulture | null |
The field of pollination management cannot be placed wholly within any other field, because it bridges several fields. It draws from horticulture, apiculture, zoology (especially entomology), ecology, and botany.
Improving pollination with suboptimal bee densities
Growers’ demand for beehives far exceeds the available... | Pollination management | Wikipedia | 250 | 325663 | https://en.wikipedia.org/wiki/Pollination%20management | Technology | Horticulture | null |
In discrete mathematics, particularly in graph theory, a graph is a structure consisting of a set of objects where some pairs of the objects are in some sense "related". The objects are represented by abstractions called vertices (also called nodes or points) and each of the related pairs of vertices is called an edge ... | Graph (discrete mathematics) | Wikipedia | 508 | 325806 | https://en.wikipedia.org/wiki/Graph%20%28discrete%20mathematics%29 | Mathematics | Discrete mathematics | null |
Generally, the vertex set is taken to be finite (which implies that the edge set is also finite). Sometimes infinite graphs are considered, but they are usually viewed as a special kind of binary relation, because most results on finite graphs either do not extend to the infinite case or need a rather different proof... | Graph (discrete mathematics) | Wikipedia | 488 | 325806 | https://en.wikipedia.org/wiki/Graph%20%28discrete%20mathematics%29 | Mathematics | Discrete mathematics | null |
In the edge directed from to , the vertices and are called the endpoints of the edge, the tail of the edge and the head of the edge. The edge is said to join and and to be incident on and on . A vertex may exist in a graph and not belong to an edge. The edge is called the inverted edge of . Multiple edges, no... | Graph (discrete mathematics) | Wikipedia | 512 | 325806 | https://en.wikipedia.org/wiki/Graph%20%28discrete%20mathematics%29 | Mathematics | Discrete mathematics | null |
Types of graphs
Oriented graph
One definition of an oriented graph is that it is a directed graph in which at most one of and may be edges of the graph. That is, it is a directed graph that can be formed as an orientation of an undirected (simple) graph.
Some authors use "oriented graph" to mean the same as "dire... | Graph (discrete mathematics) | Wikipedia | 485 | 325806 | https://en.wikipedia.org/wiki/Graph%20%28discrete%20mathematics%29 | Mathematics | Discrete mathematics | null |
A bipartite graph is a simple graph in which the vertex set can be partitioned into two sets, W and X, so that no two vertices in W share a common edge and no two vertices in X share a common edge. Alternatively, it is a graph with a chromatic number of 2.
In a complete bipartite graph, the vertex set is the union of ... | Graph (discrete mathematics) | Wikipedia | 491 | 325806 | https://en.wikipedia.org/wiki/Graph%20%28discrete%20mathematics%29 | Mathematics | Discrete mathematics | null |
Advanced classes
More advanced kinds of graphs are:
Petersen graph and its generalizations;
perfect graphs;
cographs;
chordal graphs;
other graphs with large automorphism groups: vertex-transitive, arc-transitive, and distance-transitive graphs;
strongly regular graphs and their generalizations distance-regular ... | Graph (discrete mathematics) | Wikipedia | 435 | 325806 | https://en.wikipedia.org/wiki/Graph%20%28discrete%20mathematics%29 | Mathematics | Discrete mathematics | null |
The diagram is a schematic representation of the graph with vertices and edges
In computer science, directed graphs are used to represent knowledge (e.g., conceptual graph), finite-state machines, and many other discrete structures.
A binary relation R on a set X defines a directed graph. An element x of X is a dir... | Graph (discrete mathematics) | Wikipedia | 471 | 325806 | https://en.wikipedia.org/wiki/Graph%20%28discrete%20mathematics%29 | Mathematics | Discrete mathematics | null |
Injection moulding (U.S. spelling: injection molding) is a manufacturing process for producing parts by injecting molten material into a mould, or mold. Injection moulding can be performed with a host of materials mainly including metals (for which the process is called die-casting), glasses, elastomers, confections, a... | Injection moulding | Wikipedia | 458 | 325831 | https://en.wikipedia.org/wiki/Injection%20moulding | Technology | Materials | null |
Injection moulding uses a ram or screw-type plunger to force molten plastic or rubber material into a mould cavity; this solidifies into a shape that has conformed to the contour of the mould. It is most commonly used to process both thermoplastic and thermosetting polymers, with the volume used of the former being con... | Injection moulding | Wikipedia | 386 | 325831 | https://en.wikipedia.org/wiki/Injection%20moulding | Technology | Materials | null |
When thermoplastics are moulded, typically pelletised raw material is fed through a hopper into a heated barrel with a reciprocating screw. Upon entrance to the barrel, the temperature increases and the Van der Waals forces that resist relative flow of individual chains are weakened as a result of increased space betwe... | Injection moulding | Wikipedia | 502 | 325831 | https://en.wikipedia.org/wiki/Injection%20moulding | Technology | Materials | null |
Then, the mould closes and the process is repeated | Injection moulding | Wikipedia | 11 | 325831 | https://en.wikipedia.org/wiki/Injection%20moulding | Technology | Materials | null |
For a two-shot mould, two separate materials are incorporated into one part. This type of injection moulding is used to add a soft touch to knobs, to give a product multiple colours, or to produce a part with multiple performance characteristics.
For thermosets, typically two different chemical components are injected... | Injection moulding | Wikipedia | 405 | 325831 | https://en.wikipedia.org/wiki/Injection%20moulding | Technology | Materials | null |
A parting line, sprue, gate marks, and ejector pin marks are usually present on the final part. None of these features are typically desired, but are unavoidable due to the nature of the process. Gate marks occur at the gate that joins the melt-delivery channels (sprue and runner) to the part forming cavity. Parting l... | Injection moulding | Wikipedia | 459 | 325831 | https://en.wikipedia.org/wiki/Injection%20moulding | Technology | Materials | null |
The industry expanded rapidly in the 1940s because World War II created a huge demand for inexpensive, mass-produced products. In 1946, American inventor James Watson Hendry built the first screw injection machine, which allowed much more precise control over the speed of injection and the quality of articles produced.... | Injection moulding | Wikipedia | 506 | 325831 | https://en.wikipedia.org/wiki/Injection%20moulding | Technology | Materials | null |
Injection moulding machines consist of a material hopper, an injection ram or screw-type plunger, and a heating unit. Also known as platens, they hold the moulds in which the components are shaped. Presses are rated by tonnage, which expresses the amount of clamping force that the machine can exert. This force keeps th... | Injection moulding | Wikipedia | 263 | 325831 | https://en.wikipedia.org/wiki/Injection%20moulding | Technology | Materials | null |
Since moulds have been expensive to manufacture, they were usually only used in mass production where thousands of parts were being produced. Typical moulds are constructed from hardened steel, pre-hardened steel, aluminium, and/or beryllium-copper alloy. The choice of material for the mold is not only based on cost co... | Injection moulding | Wikipedia | 460 | 325831 | https://en.wikipedia.org/wiki/Injection%20moulding | Technology | Materials | null |
The amount of resin required to fill the sprue, runner and cavities of a mould comprises a "shot". Trapped air in the mould can escape through air vents that are ground into the parting line of the mould, or around ejector pins and slides that are slightly smaller than the holes retaining them. If the trapped air is no... | Injection moulding | Wikipedia | 348 | 325831 | https://en.wikipedia.org/wiki/Injection%20moulding | Technology | Materials | null |
A mould is usually designed so that the moulded part reliably remains on the ejector (B) side of the mould when it opens, and draws the runner and the sprue out of the (A) side along with the parts. The part then falls freely when ejected from the (B) side. Tunnel gates, also known as submarine or mould gates, are loca... | Injection moulding | Wikipedia | 478 | 325831 | https://en.wikipedia.org/wiki/Injection%20moulding | Technology | Materials | null |
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