Linear and nonlinear temperature-dependent transmission/absorption characteristics of cadmium telluride crystal for terahertz generation

2020 ◽  
Vol 59 (11) ◽  
pp. 3417
Author(s):  
Archana Kumari ◽  
A. K. Chaudhary ◽  
M. Venkatesh
Keyword(s):  
Cadmium Telluride ◽  
Terahertz Generation ◽  
Temperature Dependent ◽  
Nonlinear Temperature ◽  
Linear And Nonlinear ◽  
Absorption Characteristics

scholarly journals A new boundary element algorithm for modeling and simulation of nonlinear thermal stresses in micropolar FGA composites with temperature-dependent properties

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Mohamed Abdelsabour Fahmy
Keyword(s):  
Modeling And Simulation ◽  
Boundary Element ◽  
Thermal Stresses ◽  
Computation Time ◽  
Functionally Graded ◽  
Temperature Dependent ◽  
Time Step ◽  
Kirchhoff Transformation ◽  
Nonlinear Temperature ◽  
Temperature Dependent Properties

AbstractThe main aim of this article is to develop a new boundary element method (BEM) algorithm to model and simulate the nonlinear thermal stresses problems in micropolar functionally graded anisotropic (FGA) composites with temperature-dependent properties. Some inside points are chosen to treat the nonlinear terms and domain integrals. An integral formulation which is based on the use of Kirchhoff transformation is firstly used to simplify the transient heat conduction governing equation. Then, the residual nonlinear terms are carried out within the current formulation. The domain integrals can be effectively treated by applying the Cartesian transformation method (CTM). In the proposed BEM technique, the nonlinear temperature is computed on the boundary and some inside domain integral. Then, nonlinear displacement can be calculated at each time step. With the calculated temperature and displacement distributions, we can obtain the values of nonlinear thermal stresses. The efficiency of our proposed methodology has been improved by using the communication-avoiding versions of the Arnoldi (CA-Arnoldi) preconditioner for solving the resulting linear systems arising from the BEM to reduce the iterations number and computation time. The numerical outcomes establish the influence of temperature-dependent properties on the nonlinear temperature distribution, and investigate the effect of the functionally graded parameter on the nonlinear displacements and thermal stresses, through the micropolar FGA composites with temperature-dependent properties. These numerical outcomes also confirm the validity, precision and effectiveness of the proposed modeling and simulation methodology.

On the time delay of the photoplastic effect

1986 ◽  
Vol 1 (1) ◽  
pp. 3-6 ◽  
Author(s):  
Joseph Pellegrino ◽  
J. M. Galligan
Keyword(s):  
Time Delay ◽  
Temperature Dependence ◽  
Cadmium Telluride ◽  
Deformation Temperature ◽  
Mercury Cadmium Telluride ◽  
Charge Carriers ◽  
Temperature Dependent ◽  
Simple Analysis ◽  
Photoplastic Effect

Photoplasticity in mercury cadmium telluride, Hg1-x Cdx Te with x = 0.3, has been studied as a function of light frequency and deformation temperature. We show that there is an easily measurable time delay accompanying irradiation of the crystal and the change in stress. This time delay is temperature dependent, suggesting a diffusion of charge carriers, introduced by the light, to the interior of the crystal. A simple analysis is given of the observed temperature dependence that is consistent with the experiments.

Simplified Analysis of Heat-Curved Steel Girders

2003 ◽  
Vol 1861 (1) ◽  
pp. 101-114
Author(s):  
Antoine N. Gergess ◽  
Rajan Sen
Keyword(s):  
Cross Section ◽  
High Performance ◽  
Three Dimensional ◽  
Nonlinear Finite Element ◽  
Steel Bridge ◽  
Temperature Dependent ◽  
Iterative Analysis ◽  
Nonlinear Temperature ◽  
Simplified Analysis ◽  
Single Heating

Heat curving is commonly used in the fabrication of curved structural steel bridge girders. A two-dimensional superposition analysis known as the Duhamel Analogy was used for numerical modeling in the development of the AASHTO code provisions. This iterative analysis can take into consideration multiple heating–cooling cycles, initial residual stresses, temperature-dependent material properties, and the nonlinear temperature distribution across the girder cross section. A simplified analysis based on the Duhamel Analogy that can be carried out by using hand calculations is described. The curvatures obtained by this method are within 15% of the measured curvatures, which are very comparable to the results obtained by using the Duhamel Analogy or the three-dimensional, nonlinear, finite element solution. The background, basis, and steps required for the proposed analysis are described; and an illustrative numerical example is presented. The proposed analysis may be used to estimate curvatures or to determine the maximum fabrication temperature and the heating width for a single heating–cooling cycle for steels such as high-performance steel not covered by the current AASHTO provisions.

Predicting Inlet Temperature Effects on the Pressure-Drop of Heated Porous Medium Channel Flows Using the M-HDD Model

2004 ◽  
Vol 126 (2) ◽  
pp. 301-303 ◽  
Author(s):  
Arunn Narasimhan ◽  
Jose´ L. Lage
Keyword(s):  
Porous Medium ◽  
Pressure Drop ◽  
Inlet Temperature ◽  
Temperature Dependent ◽  
Temperature Dependent Viscosity ◽  
Viscosity Effects ◽  
Nonisothermal Flows ◽  
Nonlinear Temperature ◽  
Global Pressure ◽  
Dependent Viscosity

A Modified Hazen-Dupuit-Darcy (M-HDD) model, incorporating nonlinear temperature-dependent viscosity effects, has been proposed recently for predicting the global pressure-drop of nonisothermal flows across a heated (or cooled) porous medium channel. Numerical simulations, mimicking the flow of a liquid with nonlinear temperature-dependent viscosity, are presented now for establishing the influence of inlet temperature on the pressure-drop and on the predictive capabilities of the M-HDD model. As a result, new generalized correlations for predicting the coefficients of the M-HDD model are derived. The results not only demonstrate the importance of fluid inlet temperature on predicting the global pressure-drop but they also extend the applicability of the M-HDD model.

Shallow Incorporation of Nitrogen in HPSI 4H-SiC through the Laser Enhanced Diffusion Process

2012 ◽  
Vol 717-720 ◽  
pp. 813-816 ◽  
Author(s):  
William W. Sullivan III ◽  
Cameron Hettler ◽  
James Dickens
Keyword(s):  
Diffusion Process ◽  
Thermal Model ◽  
Surface Concentration ◽  
Laser Pulses ◽  
Measured Data ◽  
Temperature Dependent ◽  
Near Surface ◽  
Enhanced Diffusion ◽  
Laser Absorption ◽  
Nonlinear Temperature

This paper investigates n-type doping of point-defect compensated high purity semi-insulating (HPSI) 4H-SiC using a pulsed laser (10 ns FWHM @ 260 nm) for the introduction of nitrogen to shallow depths. A thermal model is presented using COMSOL Multiphysics featuring nonlinear temperature dependent material properties and a volumetric heat source term that takes into account the laser absorption depth for common ultraviolet irradiating wavelengths. The temperature distribution in the material and the amount of time that the surface and near-surface regions are at high temperature determines how many laser pulses are required to dope to the desired depth, and simulation results are presented and fit to measured data. The simulations and measured data show that for shallow doping a short wavelength ultraviolet laser should be used to localize the heat at the surface so the dopant can’t diffuse deep into the material. The laser enhanced diffusion process has been used to incorporate nitrogen into HPSI 4H-SiC with a measured surface concentration greater than 1020 cm-3 and a nonlinear thermal model was built.

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