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very difficult to measure, only about 60 stellar parallaxes had been obtained by the end of the 19th century, mostly by use of the filar micrometer. Astrographs using astronomical photographic plates sped the process in the early 20th century. Automated plate-measuring machines and more sophisticated computer technolog... | {
"page_id": 202661,
"title": "Stellar parallax"
} |
kilometer (about 43 AU) distance of the spacecraft from Earth yielded a discernible parallax of arcminutes, allowing the parallax to be seen visually without instrumentation. The European Space Agency's Gaia mission, launched 19 December 2013, is expected to measure parallax angles to an accuracy of 10 microarcseconds ... | {
"page_id": 202661,
"title": "Stellar parallax"
} |
Sun through S. The vertices v and v' of the elliptical projection of the path of S are projections of positions of Earth E and E′ such that a line E-E′ intersects the line Sun-S at a right angle; the triangle created by points E, E′ and S is an isosceles triangle with the line Sun-S as its symmetry axis. Any stars that... | {
"page_id": 202661,
"title": "Stellar parallax"
} |
the length of the leg of a right triangle adjacent to the angle of one arcsecond at one vertex, where the other leg is 1 AU long. Because stellar parallaxes and distances all involve such skinny right triangles, a convenient trigonometric approximation can be used to convert parallaxes (in arcseconds) to distance (in p... | {
"page_id": 202661,
"title": "Stellar parallax"
} |
the angle is small compared to 1 radian), tan x ≈ x radians = x ⋅ 180 π degrees = x ⋅ 180 ⋅ 3600 π arcseconds , {\displaystyle \tan x\approx x{\text{ radians}}=x\cdot {\frac {180}{\pi }}{\text{ degrees}}=x\cdot 180\cdot {\frac {3600}{\pi }}{\text{ arcseconds}},} so the parallax, measured in arcseconds, is p ″ ≈ 1 au ... | {
"page_id": 202661,
"title": "Stellar parallax"
} |
van Leeuwen recommends that the parallax error be no more than 10% of the total parallax when computing this error estimate. == See also == Apparent place – position of an object in space as seen by an observer, which may differ from actual position due to geometric and physical effectsPages displaying wikidata descrip... | {
"page_id": 202661,
"title": "Stellar parallax"
} |
The Vectors of Mind is a book published by American psychologist Louis Leon Thurstone in 1935 that summarized Thurstone's methodology for multiple factor analysis. == Overview == The Vectors of Mind presents Thurstone's methods for conducting a factor analysis on a set of variables that allow for more than one factor, ... | {
"page_id": 53417900,
"title": "The Vectors of Mind"
} |
method. He foresees a bright future for the use of factor analysis and expects to see the simplification of the computational methods. He expects factor analysis to become an important technique it the early stages of science. For example, the laws of classical mechanics could have been revealed by a factor analysis, b... | {
"page_id": 53417900,
"title": "The Vectors of Mind"
} |
communality of the test battery-, a specific factor that is unique to one test-the specificity of the test-, and the error variance. Factor analysis can determine the communality of a test, but cannot separate the uniqueness into the specific factor and the error factors. The reliability coefficient is the sum of commu... | {
"page_id": 53417900,
"title": "The Vectors of Mind"
} |
analysis with a single factor (a matrix with rank one) thirty years, but recent advances have made it possible to extend factor analysis to multiple factors. The shortcomings of Spearman's method of tetrad differences are detailed and the current approach found to be more accurate. A numerical example is given. Chapter... | {
"page_id": 53417900,
"title": "The Vectors of Mind"
} |
from subject scores, and well as for estimating subjects scores from the primary traits (for estimating the components of variance of the subject scores). Appendices. I: Outline of Calculations for the Centroid Method with Unknown Diagonals. II: A Method of Finding the Roots of a Polynomial. III: A Method of Determinin... | {
"page_id": 53417900,
"title": "The Vectors of Mind"
} |
continuous variable correlations from dichotomous variables. Tetrachorics require extensive calculations but in early 1933, he and two colleagues at the University of Chicago published a set of computing diagrams that greatly reduce the calculations needed for those coefficients, another aspect of making his method of ... | {
"page_id": 53417900,
"title": "The Vectors of Mind"
} |
The nonribosomal code refers to key amino acid residues and their positions within the primary sequence of an adenylation domain of a nonribosomal peptide synthetase used to predict substrate specificity and thus (partially) the final product. Analogous to the nonribosomal code is prediction of peptide composition by D... | {
"page_id": 42735534,
"title": "Nonribosomal code"
} |
and have domain variations, additions and/or exclusions. == Supporting examples == The A-domains have 8 amino acid-long non-ribosomal signatures. LTKVGHIG → Asp (Aspartic acid) VGEIGSID → Orn (Orinithine) AWMFAAVL → Val (Valine) == See also == Nonribosomal peptide Natural product Secondary metabolite == References == | {
"page_id": 42735534,
"title": "Nonribosomal code"
} |
The constructive cooperative coevolutionary algorithm (also called C3) is a global optimisation algorithm in artificial intelligence based on the multi-start architecture of the greedy randomized adaptive search procedure (GRASP). It incorporates the existing cooperative coevolutionary algorithm (CC). The considered pr... | {
"page_id": 44636079,
"title": "Constructive cooperative coevolution"
} |
constructed. This constructed solution is then used as the initial solution in Phase II, the local improvement phase. The CC algorithm is employed to further optimise the constructed solution. A cycle of Phase II includes optimising the subproblems separately while keeping the parameters of the other subproblems fixed ... | {
"page_id": 44636079,
"title": "Constructive cooperative coevolution"
} |
an increasing subset of subproblems. The subset increases until the entire set of all subproblems is included. During these initial optimisations, the subpopulation of the latest included subproblem is evolved by a multi-objective evolutionary algorithm. For the fitness calculations of the members of the subpopulation,... | {
"page_id": 44636079,
"title": "Constructive cooperative coevolution"
} |
In signal processing, the power spectrum S x x ( f ) {\displaystyle S_{xx}(f)} of a continuous time signal x ( t ) {\displaystyle x(t)} describes the distribution of power into frequency components f {\displaystyle f} composing that signal. According to Fourier analysis, any physical signal can be decomposed into a num... | {
"page_id": 202672,
"title": "Spectral density"
} |
{\displaystyle E(t)} as it fluctuates at an extremely high frequency. Obtaining a spectrum from time series such as these involves the Fourier transform, and generalizations based on Fourier analysis. In many cases the time domain is not specifically employed in practice, such as when a dispersive prism is used to obta... | {
"page_id": 202672,
"title": "Spectral density"
} |
spectral density (ESD) would have units of V2 s Hz−1, since energy has units of power multiplied by time (e.g., watt-hour). In the general case, the units of PSD will be the ratio of units of variance per unit of frequency; so, for example, a series of displacement values (in meters) over time (in seconds) will have PS... | {
"page_id": 202672,
"title": "Spectral density"
} |
π f t x ( t ) d t , {\displaystyle {\hat {x}}(f)=\int _{-\infty }^{\infty }e^{-i2\pi ft}x(t)\ dt,} is the Fourier transform of x ( t ) {\displaystyle x(t)} at frequency f {\displaystyle f} (in Hz). The theorem also holds true in the discrete-time cases. Since the integral on the left-hand side is the energy of the sign... | {
"page_id": 202672,
"title": "Spectral density"
} |
x ( f ) {\displaystyle {\bar {S}}_{xx}(f)} at frequency f {\displaystyle f} , one could insert between the transmission line and the resistor a bandpass filter which passes only a narrow range of frequencies ( Δ f {\displaystyle \Delta f} , say) near the frequency of interest and then measure the total energy E ( f ) {... | {
"page_id": 202672,
"title": "Spectral density"
} |
transform of x n . {\displaystyle x_{n}.} The sampling interval Δ t {\displaystyle \Delta t} is needed to keep the correct physical units and to ensure that we recover the continuous case in the limit Δ t → 0. {\displaystyle \Delta t\to 0.} But in the mathematical sciences the interval is often set to 1, which simplifi... | {
"page_id": 202672,
"title": "Spectral density"
} |
period T {\displaystyle T} is centered about some arbitrary time t = t 0 {\displaystyle t=t_{0}} : P = lim T → ∞ 1 T ∫ t 0 − T / 2 t 0 + T / 2 | x ( t ) | 2 d t {\displaystyle P=\lim _{T\to \infty }{\frac {1}{T}}\int _{t_{0}-T/2}^{t_{0}+T/2}\left|x(t)\right|^{2}\,dt} Whenever it is more convenient to deal with time lim... | {
"page_id": 202672,
"title": "Spectral density"
} |
spectral density: The convolution theorem then allows regarding | x ^ T ( f ) | 2 {\displaystyle |{\hat {x}}_{T}(f)|^{2}} as the Fourier transform of the time convolution of x T ∗ ( − t ) {\displaystyle x_{T}^{*}(-t)} and x T ( t ) {\displaystyle x_{T}(t)} , where * represents the complex conjugate. In order to deduce ... | {
"page_id": 202672,
"title": "Spectral density"
} |
{\displaystyle z} and t {\displaystyle t} are dummy variables. So, we have F { x T ∗ ( − t ) } = ∫ − ∞ ∞ x T ∗ ( − t ) e − i 2 π f t d t = ∫ − ∞ ∞ x T ∗ ( t ) e i 2 π f t d t = ∫ − ∞ ∞ x T ∗ ( t ) [ e − i 2 π f t ] ∗ d t = [ ∫ − ∞ ∞ x T ( t ) e − i 2 π f t d t ] ∗ = [ F { x T ( t ) } ] ∗ = [ x ^ T ( f ) ] ∗ {\displayst... | {
"page_id": 202672,
"title": "Spectral density"
} |
∞ ∞ [ ∫ − ∞ ∞ x T ∗ ( t − τ ) x T ( t ) d t ] e − i 2 π f τ d τ , {\displaystyle {\begin{aligned}\left|{\hat {x}}_{T}(f)\right|^{2}&=[{\hat {x}}_{T}(f)]^{*}\cdot {\hat {x}}_{T}(f)\\&={\mathcal {F}}\left\{x_{T}^{*}(-t)\right\}\cdot {\mathcal {F}}\left\{x_{T}(t)\right\}\\&={\mathcal {F}}\left\{u(t)\right\}\cdot {\mathcal... | {
"page_id": 202672,
"title": "Spectral density"
} |
authors use this equality to actually define the power spectral density. The power of the signal in a given frequency band [ f 1 , f 2 ] {\displaystyle [f_{1},f_{2}]} , where 0 < f 1 < f 2 {\displaystyle 0<f_{1}<f_{2}} , can be calculated by integrating over frequency. Since S x x ( − f ) = S x x ( f ) {\displaystyle S... | {
"page_id": 202672,
"title": "Spectral density"
} |
times t n = t 0 + ( n Δ t ) {\displaystyle t_{n}=t_{0}+(n\,\Delta t)} for a total measurement period T = ( 2 N + 1 ) Δ t {\displaystyle T=(2N+1)\,\Delta t} . S x x ( f ) = lim N → ∞ ( Δ t ) 2 T | ∑ n = − N N x n e − i 2 π f n Δ t | 2 {\displaystyle S_{xx}(f)=\lim _{N\to \infty }{\frac {(\Delta t)^{2}}{T}}\left|\sum _{n... | {
"page_id": 202672,
"title": "Spectral density"
} |
begin, let us consider the average power of such a combined signal. P = lim T → ∞ 1 T ∫ − ∞ ∞ [ x T ( t ) + y T ( t ) ] ∗ [ x T ( t ) + y T ( t ) ] d t = lim T → ∞ 1 T ∫ − ∞ ∞ | x T ( t ) | 2 + x T ∗ ( t ) y T ( t ) + y T ∗ ( t ) x T ( t ) + | y T ( t ) | 2 d t {\displaystyle {\begin{aligned}P&=\lim _{T\to \infty }{\fr... | {
"page_id": 202672,
"title": "Spectral density"
} |
taken to the limit T → ∞ {\displaystyle T\to \infty } becomes the Fourier transform of a cross-correlation function. S x y ( f ) = ∫ − ∞ ∞ [ lim T → ∞ 1 T ∫ − ∞ ∞ x T ∗ ( t − τ ) y T ( t ) d t ] e − i 2 π f τ d τ = ∫ − ∞ ∞ R x y ( τ ) e − i 2 π f τ d τ S y x ( f ) = ∫ − ∞ ∞ [ lim T → ∞ 1 T ∫ − ∞ ∞ y T ∗ ( t − τ ) x T (... | {
"page_id": 202672,
"title": "Spectral density"
} |
voltage or current), their Fourier transforms x ^ ( f ) {\displaystyle {\hat {x}}(f)} and y ^ ( f ) {\displaystyle {\hat {y}}(f)} are usually restricted to positive frequencies by convention. Therefore, in typical signal processing, the full CPSD is just one of the CPSDs scaled by a factor of two. CPSD Full = 2 S x y (... | {
"page_id": 202672,
"title": "Spectral density"
} |
used in EEG monitoring, in which case SEF has variously been used to estimate the depth of anesthesia and stages of sleep. A spectral envelope is the envelope curve of the spectrum density. It describes one point in time (one window, to be precise). For example, in remote sensing using a spectrometer, the spectral enve... | {
"page_id": 202672,
"title": "Spectral density"
} |
one encounters an amplitude spectral density (ASD), which is the square root of the PSD; the ASD of a voltage signal has units of V Hz−1/2. This is useful when the shape of the spectrum is rather constant, since variations in the ASD will then be proportional to variations in the signal's voltage level itself. But it i... | {
"page_id": 202672,
"title": "Spectral density"
} |
Fourier transform (STFT) of an input signal. If the signal being analyzed can be considered a stationary process, the STFT is a good smoothed estimate of its power spectral density. === Cosmology === Primordial fluctuations, density variations in the early universe, are quantified by a power spectrum which gives the po... | {
"page_id": 202672,
"title": "Spectral density"
} |
Science & Business Media. ISBN 978-3-540-61530-9. Stein, Jonathan Y. (2000). Digital Signal Processing. New York Weinheim: Wiley-Interscience. ISBN 978-0-471-29546-4. == External links == Power Spectral Density Matlab scripts | {
"page_id": 202672,
"title": "Spectral density"
} |
Fluorochromasia (Greek flōr χρῶμα- Pronunciation: flu̇r·ō·krə′mā·zhə), is a cellular phenomenon characterized by immediate appearance of bright green fluorescence inside viable cells upon exposure to certain membrane-permeable fluorogenic substrates such as fluorescein diacetate, fluorescein dibutyrate and fluorescein ... | {
"page_id": 54466482,
"title": "Fluorochromasia"
} |
The molecular formula C13H16FNO (molar mass: 221.28 g/mol) may refer to: Blixeprodil 2-Fluorodeschloroketamine 3-Fluorodeschloroketamine | {
"page_id": 71702453,
"title": "C13H16FNO"
} |
Methylguanine may refer to: 1-Methylguanine 2-Methylguanine 3-Methylguanine 6-O-Methylguanine 7-Methylguanine | {
"page_id": 24516537,
"title": "Methylguanine"
} |
The molecular formula C6H7N5O (molar mass: 165.15 g/mol, exact mass: 165.0651 u) may refer to: 6-O-Methylguanine 7-Methylguanine | {
"page_id": 24516541,
"title": "C6H7N5O"
} |
The molecular formula C26H36O5 (molar mass: 428.56 g/mol, exact mass: 428.2563 u) may refer to: Acetomepregenol (ACM), also called mepregenol diacetate Dicirenone Domoprednate | {
"page_id": 55121853,
"title": "C26H36O5"
} |
Magnetic field viewing film is used to show stationary or (less often) slowly changing magnetic fields; it shows their location and direction. It is a translucent thin flexible sheet, coated with micro-capsules containing nickel flakes suspended in oil. When magnetic lines of force are parallel to the surface of the ca... | {
"page_id": 5576639,
"title": "Magnetic field viewing film"
} |
An ectopic hormone is a hormone produced by tumors derived from tissue that is not typically associated with its production. On the other hand, the term entopic is used to refer to hormones produced by tissue in tumors that are normally engaged in the production of that hormone. The excess hormone secretion is consider... | {
"page_id": 70195136,
"title": "Ectopic hormone"
} |
Speciation of ions refers to the changing concentration of varying forms of an ion as the pH of the solution changes. The pH of a solution of a monoprotic weak acid can be expressed in terms of the extent of dissociation. After rearranging the expression defining the acid dissociation constant, and putting pH = −log10[... | {
"page_id": 18814915,
"title": "Ion speciation"
} |
There is no precise pKa value that distinguishes between strong and weak acids because strong acids, such as sulfuric acid, are associated in very concentrated solution. Calculation of the species concentrations for a polyprotic acid is more complicated unless the pK values are separated by four or more, because three ... | {
"page_id": 18814915,
"title": "Ion speciation"
} |
In particle physics, the coincidence method (or coincidence technique) is an experimental design through which particle detectors register two or more simultaneous measurements of a particular event through different interaction channels. Detection can be made by sensing the primary particle and/or through the detectio... | {
"page_id": 73275338,
"title": "Coincidence method"
} |
question is able to trigger multiple channels that are correlated in time or space, it can be determined more likely that the particle is not a background trigger. "Chance" coincidence events may occur, in which all channels are triggered by particles which are not under investigation yet happen to interact with each c... | {
"page_id": 73275338,
"title": "Coincidence method"
} |
e n c e {\displaystyle R_{\rm {coincidence}}} can also be defined by the product of all q channels of coincidence times the raw count of particles available for detection N {\displaystyle N} : R c o i n c i d e n c e = N ∏ 1 q ϵ q {\displaystyle R_{\rm {coincidence}}=N\prod _{1}^{q}\epsilon _{q}} Therefore, the ability... | {
"page_id": 73275338,
"title": "Coincidence method"
} |
reaction n 0 → ν + p + + β − {\displaystyle n^{0}\rightarrow \nu +p^{+}+\beta ^{-}} , where n 0 {\displaystyle n^{0}} is a neutron, ν {\displaystyle \nu } is the neutrino, p + {\displaystyle p^{+}} is a proton, and β − {\displaystyle \beta ^{-}} is a beta particle. In an attempt to build on the theoretical concept of a... | {
"page_id": 73275338,
"title": "Coincidence method"
} |
method enlightened new techniques for measuring high-energy cosmic rays. On such experiment, COS-B, launched in 1975 and featured an anti-coincidence veto for charged particles, as well as three scintillation detectors to measure electron cascades caused by incoming gamma radiation. Therefore, gamma ray interactions co... | {
"page_id": 73275338,
"title": "Coincidence method"
} |
s u s p e c t e d {\displaystyle R_{suspected}} would include all coincident and all uncorrelated events. == Further reading == Handbook of Particle Detection and Imaging (Grupen, 2012) == References == | {
"page_id": 73275338,
"title": "Coincidence method"
} |
The Reactor Experiment for Neutrino Oscillation (RENO) is a short baseline reactor neutrino oscillation experiment in South Korea. The experiment was designed to either measure or set a limit on the neutrino mixing matrix parameter θ13, a parameter responsible for oscillations of electron neutrinos into other neutrino ... | {
"page_id": 31004619,
"title": "Reactor Experiment for Neutrino Oscillation"
} |
a distance of 47 km. This distance is better for observing neutrino oscillations, but requires a much larger detector due to the smaller neutrino flux. The location, near Dongshin University, has a 450 m high mountain (Mt. Guemseong), which will provide 900 m.w.e. shielding for the detector. If funded, this will contai... | {
"page_id": 31004619,
"title": "Reactor Experiment for Neutrino Oscillation"
} |
The molecular formula C20H16 (molar mass: 256.34 g/mol) may refer to: 7,12-Dimethylbenz[a]anthracene (DMBA) Triphenylethylene | {
"page_id": 24385485,
"title": "C20H16"
} |
Plant & Food Research (Māori: Rangahau Ahumāra Kai) is a New Zealand Crown Research Institute (CRI). Its purpose is to enhance the value and productivity of New Zealand's horticultural, arable, seafood and food & beverage industries. The interests of the institute are based in horticulture, arable and seafood research,... | {
"page_id": 20518862,
"title": "Plant & Food Research"
} |
Ecological extinction is "the reduction of a species to such low abundance that, although it is still present in the community, it no longer interacts significantly with other species". Ecological extinction stands out because it is the interaction ecology of a species that is important for conservation work. They stat... | {
"page_id": 11409359,
"title": "Ecological extinction"
} |
forests was evaluated by Estes et al. in a 1978 study. They compared the Rat and Near islands in the Aleutian islands to test if "sea otter predation controls epibenthic invertebrate populations (specifically sea urchins), and in turn releases the vegetation association from intense grazing". Estes and his colleagues f... | {
"page_id": 11409359,
"title": "Ecological extinction"
} |
the Chesapeake Bay ecosystem until mechanical dredges were utilized in the 1870s, resulting in overfishing of the oysters. The bay today is plagued by eutrophication due to algal blooms, and the resulting water is highly hypoxic. These algal blooms have competitively excluded any other species from surviving, including... | {
"page_id": 11409359,
"title": "Ecological extinction"
} |
to alter the vegetation in the habitat, which could have further pronounced the intensity of competition. Guanacos and rheas have been classified as a low risk for global extinction, but this simplistic view of their demography does not take into account that they have already become functionally extinct in the Argenti... | {
"page_id": 11409359,
"title": "Ecological extinction"
} |
== Modeling ecological extinction == The McConkey and Drake (2006) study is unique because it was one of the first attempts to model a density-dependent threshold relationship that described ecological extinction. They studied a seed dispersal interaction between flying foxes and trees with large seeds on the tropical ... | {
"page_id": 11409359,
"title": "Ecological extinction"
} |
is the first step to applying this framework into conservation work. While ecologists are just starting to get a grapple on the significant interactions within an ecosystem, they must continue to find an effective density threshold that can maintain the level of equilibrium species diversity. Only with this knowledge o... | {
"page_id": 11409359,
"title": "Ecological extinction"
} |
loss of pollinator mutualisms, and the effect of introduced species all have distinct pressures on native populations, these effects must be looked underneath a synergistic and not an independent framework. Climate change has the potential to exacerbate all of these processes. Nehring (1999) found a total of 16 non-ind... | {
"page_id": 11409359,
"title": "Ecological extinction"
} |
should not be difficult to incorporate into policy. To avoid mass extinction on a global scale unlike anyone has seen before, scientists must understand all of the mechanisms driving the process. It is now that the governments of the world must act in order to prevent this catastrophe of the loss of biodiversity from p... | {
"page_id": 11409359,
"title": "Ecological extinction"
} |
A time temperature indicator (TTI) is a device or smart label that shows the accumulated time-temperature history of a product. Time temperature indicators are commonly used on food, pharmaceutical, and medical products to indicate exposure to excessive temperature (and time at temperature). In contrast, a temperature ... | {
"page_id": 24188886,
"title": "Time temperature indicator"
} |
containing dye and bacteria changes color as bacteria grow and chemically changes the dye Digital TTIs: a miniature temperature data logger can be attached to the item. RFID communication can be used to retrieve the temperature log. == TTIs in the food industry == Time-temperature indicators can be used on food product... | {
"page_id": 24188886,
"title": "Time temperature indicator"
} |
producer in Switzerland | {
"page_id": 24188886,
"title": "Time temperature indicator"
} |
SM Bexel Co, Ltd. (Korean: SM벡셀, formerly known as Bexel) is a South Korean chemical company specializing in battery manufacture. It is headquartered in Yangpyeong-dong Yeongdeungpo-gu, Seoul and Gongdan-dong, Gumi, Gyeongsangbuk-do, South Korea. Founded in 1978, it also manufactures other electronic products. Manufact... | {
"page_id": 6821846,
"title": "Bexel"
} |
Indentation hardness tests are used in mechanical engineering to determine the hardness of a material to deformation. Several such tests exist, wherein the examined material is indented until an impression is formed; these tests can be performed on a macroscopic or microscopic scale. When testing metals, indentation ha... | {
"page_id": 1710040,
"title": "Indentation hardness"
} |
is perfectly flat. == Instrumented indentation == Instrumented indentation basically indents a sharp tip into the surface of a material to obtain a force-displacement curve. The results provide a lot of information about the mechanical behavior of the material, including hardness, e.g., elastic moduli and plastic defor... | {
"page_id": 1710040,
"title": "Indentation hardness"
} |
each different method, are discussed as follows. == Macroindentation tests == The term "macroindentation" is applied to tests with a larger test load, such as 1 kgf or more. There are various macroindentation tests, including: Vickers hardness test (HV), which has one of the widest scales. Widely used to test hardness ... | {
"page_id": 1710040,
"title": "Indentation hardness"
} |
microindentation hardness testing, a diamond indenter of specific geometry is impressed into the surface of the test specimen using a known applied force (commonly called a "load" or "test load") of 1 to 1000 gf. Microindentation tests typically have forces of 2 N (roughly 200 gf) and produce indentations of about 50 μ... | {
"page_id": 1710040,
"title": "Indentation hardness"
} |
Both the Knoop and Vickers indenters require polishing of the surface to achieve accurate results. Scratch tests at low loads, such as the Bierbaum microcharacter test, performed with either 3 gf or 9 gf loads, preceded the development of microhardness testers using traditional indenters. In 1925, Smith and Sandland of... | {
"page_id": 1710040,
"title": "Indentation hardness"
} |
main sources of error with indentation tests are poor technique, poor calibration of the equipment, and the strain hardening effect of the process. However, it has been experimentally determined through "strainless hardness tests" that the effect is minimal with smaller indentations. Surface finish of the part and the ... | {
"page_id": 1710040,
"title": "Indentation hardness"
} |
{\displaystyle \sigma _{y}} , of many materials is proportional to the hardness by a constant known as the constrain factor, C. H = C σ y {\displaystyle H=C\sigma _{y}} where: C ≈ { 3 large E / σ y (ex. metals) 1.5 small E / σ y (ex. glasses) {\displaystyle C\approx {\begin{cases}3&{\text{large }}E/\sigma _{y}{\text{ (... | {
"page_id": 1710040,
"title": "Indentation hardness"
} |
Hexaphosphabenzene is a valence isoelectronic analogue of benzene and is expected to have a similar planar structure due to resonance stabilization and its sp2 nature. Although several other allotropes of phosphorus are stable, no evidence for the existence of P6 has been reported. Preliminary ab initio calculations on... | {
"page_id": 65214425,
"title": "Hexaphosphabenzene"
} |
varied have also been reported. These include P6 triple‐decker complexes for Ti, V, Nb, and W, whereby the synthetic method is still based on the originally reported thermolysis of [CpM(CO)2/3]2 with P4. == Electron count == If one regards the planar P6 ring as a 6π electron donor ligand, then [{(η5-Me5C5)Mo}2(μ,η6-P6)... | {
"page_id": 65214425,
"title": "Hexaphosphabenzene"
} |
with one unpaired electron. Accordingly, [{(η5- Me5C5)Mo}2(μ,η6-P6)]+ is detected by ESI mass spectrometry. The crystal structure of the teal product shows that the triple‐decker geometry is retained during the one‐electron oxidation of [{(η5- Me5C5)Mo}2(μ,η6-P6)]. The Mo—Mo bond length of the [{(η5- Me5C5)Mo}2(μ,η6-P6... | {
"page_id": 65214425,
"title": "Hexaphosphabenzene"
} |
Me5C5)Mo}2(μ,η6-P6)] in pure toluene and the solution shows the bright orange color of the complex cation [Cu([{(η5- Me5C5)Mo}2(μ,η6-P6)])2]+. However, analysis of crystals from this solution reveals a distorted tetrahedral coordination environment around Cu. The resulting Cu—P distances are somewhat shorter than their... | {
"page_id": 65214425,
"title": "Hexaphosphabenzene"
} |
to about 2.22 Å, whilst the third unit shows an unsymmetrical coordination with long Tl—P distances of approximately 3.42 and 3.69 Å and no P—P bond elongation. Although the environment of Tl+ is distinctly different from that of Cu+ and Ag+, their structures are related by the two‐dimensional coordination network that... | {
"page_id": 65214425,
"title": "Hexaphosphabenzene"
} |
of chemical bonding models. It can therefore recover Lewis bonding elements such as 1c–2e core electrons and lone pairs, 2c–2e objects which are two-center two-electron bonds, as well as delocalized many-center bonding elements with respect to aromaticity. The AdNDP analysis of the seven representative low-lying P6 str... | {
"page_id": 65214425,
"title": "Hexaphosphabenzene"
} |
filling of the unoccupied molecular orbitals involved in vibronic coupling in P6 with electron pairs of Mo atoms. Specifically, from molecular orbital analysis it was determined that, upon complex formation, the LUMO in the isolated P6 structure is now occupied in the triple-decker complex as a result of the appreciabl... | {
"page_id": 65214425,
"title": "Hexaphosphabenzene"
} |
Daniel Jurafsky is a professor of linguistics and computer science at Stanford University, and also an author. With Daniel Gildea, he is known for developing the first automatic system for semantic role labeling (SRL). He is the author of The Language of Food: A Linguist Reads the Menu (2014) and a textbook on speech a... | {
"page_id": 5576666,
"title": "Dan Jurafsky"
} |
Career Award 2002. MacArthur Fellowship 2019. LSA Fellow 2022. Atkinson Prizes in Psychological and Cognitive Sciences == References == == External links == Dan Jurafsky's Home Page at Stanford University Bibliography of works by Dan Jurafsky | {
"page_id": 5576666,
"title": "Dan Jurafsky"
} |
In physics, the eightfold way is an organizational scheme for a class of subatomic particles known as hadrons that led to the development of the quark model. Both the American physicist Murray Gell-Mann and the Israeli physicist Yuval Ne'eman independently and simultaneously proposed the idea in 1961. The name comes fr... | {
"page_id": 1185756,
"title": "Eightfold way (physics)"
} |
their attempts to understand the growing collection of known particles. The discovery of new mesons and baryons continued through the 1950s; the number of known "elementary" particles ballooned. Physicists were interested in understanding hadron-hadron interactions via the strong interaction. The concept of isospin, in... | {
"page_id": 1185756,
"title": "Eightfold way (physics)"
} |
points of differences between the eightfold way and the quark model it inspired, which suggests the mesons should be grouped into nonets (groups of nine). ==== Meson octet ==== The eightfold way organizes eight of the lowest spin-0 mesons into an octet. They are: K0, K+, K− and K0 kaons π+, π0, and π− pions η, the eta ... | {
"page_id": 1185756,
"title": "Eightfold way (physics)"
} |
noticed (1961) that groups of particles were related to each other in a way that matched the representation theory of SU(3). From that, it was inferred that there is an approximate symmetry of the universe which is represented by the group SU(3). Finally (1964), this led to the discovery of three light quarks (up, down... | {
"page_id": 1185756,
"title": "Eightfold way (physics)"
} |
A={\begin{pmatrix}{\phantom {-}}0&1&0\\-1&0&0\\{\phantom {-}}0&0&1\end{pmatrix}}} is a transformation that simultaneously turns all the up quarks in the universe into down quarks and conversely. More specifically, these flavour rotations are exact symmetries if only strong force interactions are looked at, but they are... | {
"page_id": 1185756,
"title": "Eightfold way (physics)"
} |
(proton, neutron, Σ+, Σ0, Σ−, Ξ−, Ξ0, Λ). This corresponds to an 8-dimensional ("octet") representation of the group SU(3). Since A is an approximate symmetry, all the particles in this octet have similar mass. Every Lie group has a corresponding Lie algebra, and each group representation of the Lie group can be mapped... | {
"page_id": 1185756,
"title": "Eightfold way (physics)"
} |
Mikhail (Michel) Dyakonov (born 1940 in Leningrad) is a Russian professor of physics at Laboratoire Charles Coulomb (L2C), Université Montpellier - CNRS in France. == Career == His name is connected with several physical phenomena: Dyakonov–Perel spin relaxation mechanism, Dyakonov–Shur plasma wave instability. In 1971... | {
"page_id": 59643870,
"title": "Mikhail Dyakonov"
} |
Chemical vapor deposition (CVD) is a vacuum deposition method used to produce high-quality, and high-performance, solid materials. The process is often used in the semiconductor industry to produce thin films. In typical CVD, the wafer (substrate) is exposed to one or more volatile precursors, which react and/or decomp... | {
"page_id": 6111,
"title": "Chemical vapor deposition"
} |
vapor: Aerosol assisted CVD (AACVD) – CVD in which the precursors are transported to the substrate by means of a liquid/gas aerosol, which can be generated ultrasonically. This technique is suitable for use with non-volatile precursors. Direct liquid injection CVD (DLICVD) – CVD in which the precursors are in liquid fo... | {
"page_id": 6111,
"title": "Chemical vapor deposition"
} |
at high rates and low temperatures. Atomic-layer CVD (ALCVD) – Deposits successive layers of different substances to produce layered, crystalline films. See Atomic layer epitaxy. Combustion chemical vapor deposition (CCVD) – Combustion Chemical Vapor Deposition or flame pyrolysis is an open-atmosphere, flame-based tech... | {
"page_id": 6111,
"title": "Chemical vapor deposition"
} |
CVD is commonly used to deposit conformal films and augment substrate surfaces in ways that more traditional surface modification techniques are not capable of. CVD is extremely useful in the process of atomic layer deposition at depositing extremely thin layers of material. A variety of applications for such films exi... | {
"page_id": 6111,
"title": "Chemical vapor deposition"
} |
or diborane are added to the CVD chamber. Diborane increases the growth rate, but arsine and phosphine decrease it. === Silicon dioxide === Silicon dioxide (usually called simply "oxide" in the semiconductor industry) may be deposited by several different processes. Common source gases include silane and oxygen, dichlo... | {
"page_id": 6111,
"title": "Chemical vapor deposition"
} |
PH3 + 5 O2 → 2 P2O5 + 6 H2 Glasses containing both boron and phosphorus (borophosphosilicate glass, BPSG) undergo viscous flow at lower temperatures; around 850 °C is achievable with glasses containing around 5 weight % of both constituents, but stability in air can be difficult to achieve. Phosphorus oxide in high con... | {
"page_id": 6111,
"title": "Chemical vapor deposition"
} |
in plasma to deposit SiNH: 2 SiH4 + N2 → 2 SiNH + 3 H2 SiH4 + NH3 → SiNH + 3 H2 These films have much less tensile stress, but worse electrical properties (resistivity 106 to 1015 Ω·cm, and dielectric strength 1 to 5 MV/cm). === Metals === Tungsten CVD, used for forming conductive contacts, vias, and plugs on a semicon... | {
"page_id": 6111,
"title": "Chemical vapor deposition"
} |
to synthesize graphene. Although many advancements have been made, the processes listed below are not commercially viable yet. Carbon source The most popular carbon source that is used to produce graphene is methane gas. One of the less popular choices is petroleum asphalt, notable for being inexpensive but more diffic... | {
"page_id": 6111,
"title": "Chemical vapor deposition"
} |
material play a big role in production of graphene. Most systems use LPCVD with pressures ranging from 1 to 1500 Pa. However, some still use APCVD. Low pressures are used more commonly as they help prevent unwanted reactions and produce more uniform thickness of deposition on the substrate. On the other hand, temperatu... | {
"page_id": 6111,
"title": "Chemical vapor deposition"
} |
in a home-built vertical cold wall system utilizing resistive heating by passing direct current through the substrate. It provided conclusive insight into a typical surface-mediated nucleation and growth mechanism involved in two-dimensional materials grown using catalytic CVD under conditions sought out in the semicon... | {
"page_id": 6111,
"title": "Chemical vapor deposition"
} |
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