Features of applying the power-law function to the analysis of the frequency dependences of the conductivity of disordered semiconductors

2020 ◽  
Author(s):  
Mikhail Ormont
Keyword(s):  
Power Law ◽  
Power Law Function ◽  
Frequency Dependences ◽  
Disordered Semiconductors

scholarly journals Unveiling the Evolution of Type I AGNs in the IR (15μm) — As Seen by ISO in the ELAIS-S1 Region

2002 ◽  
Vol 184 ◽  
pp. 167-172
Author(s):  
Israel Matute ◽  
Fabio La Franca ◽  
Carlotta Gruppioni ◽  
Francesca Pozzi ◽  
Carlo Lari
Keyword(s):  
Power Law ◽  
Luminosity Function ◽  
Evolution Model ◽  
Cosmological Evolution ◽  
Type I ◽  
Infrared Background ◽  
Power Law Function ◽  
Cosmic Infrared Background ◽  
Luminosity Evolution

AbstractWe present the first estimate of the evolution of type 1 AGNs in the IR (15 μm) obtained from the ELAIS survey in the S1 region. We find that the luminosity function (LF) of Type 1 AGNs at 15μm is fairly well represented by a double power-law function with a bright slope of 2.9 and a faint slope of 1.1. There is evidence for significant cosmological evolution according to a pure luminosity evolution model L15(z)α(l+z)k, with in a (Ωm,ΩΛ)=(1.0,0.0) cosmology. This evolution is similar to what is observed at other wavebands. From the luminosity function and its evolution, we estimate a contribution of ~ 2% from Type 1 AGN to the total Cosmic Infrared Background (CIRB) at 15 μm.

scholarly journals Light of Planck-2015 on Noncanonical Inflation

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Kh. Saaidi ◽  
A. Mohammadi ◽  
T. Golanbari
Keyword(s):  
Scalar Field ◽  
Observational Data ◽  
Power Law ◽  
Hubble Parameter ◽  
Field Model ◽  
Kinetic Term ◽  
Inflationary Scenario ◽  
Slow Roll ◽  
Power Law Function ◽  
Free Parameters

Slow-roll inflationary scenario is considered in noncanonical scalar field model supposing a power-law function for kinetic term and using two formalisms. In the first approach, the potential is picked out as a power-law function, that is, the most common approach in studying inflation. Hamilton-Jacobi approach is selected as the second formalism, so that the Hubble parameter is introduced as a function of scalar field instead of the potential. Employing the last observational data, the free parameters of the model are constrained, and the predicted form of the potential and attractor behavior of the model are studied in detail.

Taylor’s power law and fixed-precision sampling: application to abundance of fish sampled by gillnets in an African lake

2017 ◽  
Vol 74 (1) ◽  
pp. 87-100 ◽  
Author(s):  
Meng Xu ◽  
Jeppe Kolding ◽  
Joel E. Cohen
Keyword(s):  
Power Law ◽  
Fish Assemblage ◽  
Mesh Size ◽  
Stock Management ◽  
Taylor’S Power Law ◽  
Scaling Relationship ◽  
Temporal Variance ◽  
Taylor's Power Law ◽  
Power Law Function ◽  
The Mean

Taylor’s power law (TPL) describes the variance of population abundance as a power-law function of the mean abundance for a single or a group of species. Using consistently sampled long-term (1958–2001) multimesh capture data of Lake Kariba in Africa, we showed that TPL robustly described the relationship between the temporal mean and the temporal variance of the captured fish assemblage abundance (regardless of species), separately when abundance was measured by numbers of individuals and by aggregate weight. The strong correlation between the mean of abundance and the variance of abundance was not altered after adding other abiotic or biotic variables into the TPL model. We analytically connected the parameters of TPL when abundance was measured separately by the aggregate weight and by the aggregate number, using a weight–number scaling relationship. We utilized TPL to find the number of samples required for fixed-precision sampling and compared the number of samples when sampling was performed with a single gillnet mesh size and with multiple mesh sizes. These results facilitate optimizing the sampling design to estimate fish assemblage abundance with specified precision, as needed in stock management and conservation.

A note on static and dynamic calibration of constant-temperature hot-wire probes

1976 ◽  
Vol 76 (1) ◽  
pp. 145-156 ◽  
Author(s):  
H. H. Bruun
Keyword(s):  
Constant Temperature ◽  
Power Law ◽  
Comparative Investigation ◽  
Dynamic Calibration ◽  
Calibration Data ◽  
Hot Wire ◽  
Velocity Range ◽  
Static Calibration ◽  
Large Velocity ◽  
Power Law Function

This note describes a comparative investigation of static and dynamic calibration procedures for standard hot-wire probes. It is demonstrated that nearly the same sensitivity dE/dV can be obtained by both procedures. The discrepancy reported by Perry & Morrison (1971) is shown to be due mainly to a poor approximation of static calibration data over a large velocity range by a constant-exponent power-law function.

scholarly journals Parasitism alters three power laws of scaling in a metazoan community: Taylor’s law, density-mass allometry, and variance-mass allometry

2014 ◽  
Vol 112 (6) ◽  
pp. 1791-1796 ◽  
Author(s):  
Clément Lagrue ◽  
Robert Poulin ◽  
Joel E. Cohen
Keyword(s):  
Population Density ◽  
Body Mass ◽  
Power Law ◽  
Power Laws ◽  
Spatial Variance ◽  
Free Living ◽  
Power Law Function ◽  
Taylor’S Law ◽  
Animal Community ◽  
Parameter Values

How do the lifestyles (free-living unparasitized, free-living parasitized, and parasitic) of animal species affect major ecological power-law relationships? We investigated this question in metazoan communities in lakes of Otago, New Zealand. In 13,752 samples comprising 1,037,058 organisms, we found that species of different lifestyles differed in taxonomic distribution and body mass and were well described by three power laws: a spatial Taylor’s law (the spatial variance in population density was a power-law function of the spatial mean population density); density-mass allometry (the spatial mean population density was a power-law function of mean body mass); and variance-mass allometry (the spatial variance in population density was a power-law function of mean body mass). To our knowledge, this constitutes the first empirical confirmation of variance-mass allometry for any animal community. We found that the parameter values of all three relationships differed for species with different lifestyles in the same communities. Taylor's law and density-mass allometry accurately predicted the form and parameter values of variance-mass allometry. We conclude that species of different lifestyles in these metazoan communities obeyed the same major ecological power-law relationships but did so with parameters specific to each lifestyle, probably reflecting differences among lifestyles in population dynamics and spatial distribution.

Evaporation characterization of fuel spray impinging on a flat wall by laser-based measurement

2016 ◽  
Vol 18 (8) ◽  
pp. 776-784 ◽  
Author(s):  
Yuyin Zhang ◽  
Shiyan Li ◽  
Wenyuan Qi ◽  
Keiya Nishida
Keyword(s):  
Power Law ◽  
Ambient Pressure ◽  
Measurement Data ◽  
Injection System ◽  
Fuel Spray ◽  
Fuel Vapor ◽  
Flat Wall ◽  
Common Rail Injection System ◽  
Start Of Injection ◽  
Power Law Function

It is of interest for engine combustion modeling to quantify the evaporation behaviors of fuel spray impinging on a wall as the fuel atomization, evaporation, and mixing with oxygen in the combustion chamber usually dominate the subsequent combustion processes. In this study, the vapor and liquid mass distributions in diesel-like fuel sprays were quantified using the ultraviolet-visible laser absorption scattering imaging technique. The sprays were injected from a single-hole nozzle with a common-rail injection system and impinged on a flat wall at an ambient pressure of 4 MPa and an ambient temperature of 833 K. The mass of the total fuel vapor, the spray volume covered by the vapor phase, and the air mass entrained into the spray were characterized. The results indicate that the time evolution of these parameters until shortly after the end of injection can be expressed by a power-law function, Yi =  ki· ts1.5, where Yi represents the parameter like vapor mass and so on, ts is the time after start of injection, and ki is the coefficient corresponding to Yi. The physics behind this power-law function was analyzed and discussed based on the theory of atomization and evaporation, and verified using measurement data obtained under different conditions of injection quantity.

Estimating the Sizes of Sports Crowds

1984 ◽  
Vol 59 (3) ◽  
pp. 723-729 ◽  
Author(s):  
Simon Kemp
Keyword(s):  
Power Law ◽  
Power Law Function

Slides taken of stands in a sports stadium portraying crowds of from 8 to 1122 people were viewed by 137 observers. The observers tended to underestimate the actual numbers in the crowds; the accuracy of their estimates depended on the stand in which the crowds were situated and whether the observers viewed a training slide. Underestimation of size of a crowd is consistent with previous research on visual numerosity, but exponents of the power-law function relating estimated to actual numbers were in the range 0.95 to 1.13, higher than those found previously.

scholarly journals Characteristics of the Heat Flux in the Unstable Atmospheric Surface Layer

2016 ◽  
Vol 73 (11) ◽  
pp. 4519-4529 ◽  
Author(s):  
Maithili Sharan ◽  
Piyush Srivastava
Keyword(s):  
Heat Flux ◽  
Surface Layer ◽  
Temperature Gradient ◽  
Power Law ◽  
Atmospheric Surface Layer ◽  
Potential Temperature ◽  
Stability Parameter ◽  
Layer Potential ◽  
Power Law Function ◽  
The Stability

Abstract The behavior of the heat flux H with respect to the stability parameter (=z/L, where z is the height above the ground, and L is the Obukhov length) in the unstable atmospheric surface layer is analyzed within the framework of Monin–Obukhov similarity (MOS) theory. Using MOS equations, H is expressed as a function of and vertical surface-layer potential temperature gradient . A mathematical analysis is carried out to analyze the theoretical nature of heat flux with the stability parameter by considering the vertical potential temperature gradient as (i) a constant and (ii) a power-law function of heat flux. For a given value of H, two values of associated with different stability regimes are found to occur in both the conditions, suggesting the nonuniqueness of MOS equations. Turbulent data over three different sites—(i) Ranchi, India; (ii) the Met Office’s Cardington, United Kingdom, monitoring facility; and (iii) 1999 Cooperative Atmosphere–Surface Exchange Study (CASES-99; United States—are analyzed to compare the observed nature of H with that predicted by MOS. The analysis of observational data over these three sites reveals that the observed variation of H with is consistent with that obtained theoretically from MOS equations when considering the vertical temperature gradient as a power-law function of heat flux having the exponent larger than 2/3. The existence of two different values of the stability parameter for a given value of heat flux suggests that the application of heat flux as a boundary condition involves some intricacies, and it should be applied with caution in convective conditions.

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