Harmonic Wave Analysis Research Articles

Optoelectronic–thermomagnetic effect of a microelongated non-local rotating semiconductor heated by pulsed laser with varying thermal conductivity

Abstract In this study, we investigated the effect of a rotation field and magnetic field on a homogeneous photo-thermoelastic nonlocal material and how its thermal conductivity changes as a result of a linearly distributed thermal load. The thermal conductivity of an interior particle is supposed to increase linearly with temperature under the impact of laser pulses. Microelastic (microelements distribution), non-local semiconductors are used to model the problem under optoelectronic procedures, as proposed by the thermoelasticity theory. According to the microelement transport processes, the micropolar-photo-thermoelasticity theory accounts for the medium’s microelongation properties. This mathematical model is solved in two dimensions using the harmonic wave analysis. Non-local semiconductor surfaces can generate completely dimensionless displacement, temperature, microelongation, carrier density, and stress components with the appropriate boundary conditions. The effects of thermal conductivity, thermal relaxation times, magnetic pressure effect, laser pulses, and rotation parameters on wave propagation in silicon (Si) material are investigated and graphically displayed for a range of values.

A changeable thermal conductivity and optoelectronic-mechanical wave behavior in a microelongated, non-locally rotating semiconductor media

In this study, we investigate the effect of a rotation field on a homogeneous photo-thermoelastic nonlocal material and how its thermal conductivity changes as a result of a linearly distributed thermal load. The thermal conductivity of an interior particle is supposed to increase linearly with temperature. Microelastic, non-local semiconductors are used to model the problem in accordance with optoelectronic procedures, as proposed by the thermoelasticity theory. The micropolar-photo-thermoelasticity theory takes into account the medium’s microelongation properties in accordance with the microelement transport processes. This mathematical model is solved in two dimensions (2D) using harmonic wave analysis. Dimensionless components of displacement, temperature, microelongation, carrier density, and stresses are generated when the non-local semiconductor surface is subjected to the right boundary conditions. For silicon (Si) material, the wave propagation impact of the main physical fields is examined and graphically shown for various values of variable thermal conductivity, thermal relaxation durations, nonlocality, and rotation parameters.

Photo-thermoelastic wave propagation with changing thermal conductivity on excited pulsed laser nanoscale microelongated semiconductor material

Indroduction: The novel model of a non-local elastic semiconductor material that is microelongated is created. The process of photothermal transfer is responsible for the stimulation of the material. Photo-thermoelastic theories are used when the thermal conductivity is changed for the non-local medium. Under the influence of laser pulses, the effective framework describes the nanoscale microelongation instance as well as the interference between the photo-thermoelastic propagation waves in the non-local medium. It is possible to think of thermal conductivity as a linear function of temperature when electronic and thermoelastic deformation mechanisms are described. Two-dimensional deformation (2D) is used to extract the main fields, which obtained in non-dimension.Methods: Harmonic wave analysis, which is described by the normal mode, has been used to convert the basic equations into non-homogeneous higher-order ordinary differential equations. Applying a small subset of the possible non-local semiconductor surface conditions leads to exhaustive solutions.Result and Discussion: The outcomes of numerical simulations for silicon (Si) are graphically shown. There are comparisons made and explanations given for the investigated physical factors like their thermal conductivity, laser pulses and microelongation parameters.

A two-temperature model and fractional order derivative in a rotating thick hollow cylinder with the magnetic field

A novel multi-phase-lags model with fractional order derivative is introduced to study a thick hollow cylinder with two temperatures under the influence of magnetic field and rotation. The basic non-dimensional equations of the problem are discussed by using harmonic wave analysis. Numerical computations are carried out with the help of Matlab software. Comparisons are made with the results of the refined-phase-lag theory for different values of rotation and magnetic field. Comparisons also are made with the results of the refined-phase-lag theory for different values of the fractional order parameter. Some particular cases of special interest have been deduced from the present investigation.

Effects of thermal relaxation times and porosity in a Lord-Shulman and refined multi-phase lags model of generalized thermoelasticity

The aim of this article is to build a mathematical model to study the problem of generalized thermoelastic porous medium according to the Lord–Shulman model and refined multi-phase lags model. The medium is considered to be homogeneous, isotropic and porous, such that changes in the size of the fracture field are in two dimensions. Four ordinary differential equations of the modified couple stress of thermoelastic porous media are obtained instead of partial differential equations and they solved precisely. The harmonic wave analysis procedure is proposed to find systematically the appropriate solutions to the variables of stresses, displacements, the change in the temperature, and in the volume fraction field. The outcomes of the physical variables have been computed numerically and clarified graphically. The comparison between both refined multi-phase lags and Lord–Shulman models are carried out for particular values of distance and various values of thermal relaxation times. This article’s findings may be useful to many researchers and scientists in the subject of materials science, especially porous media, as well as those working on creating modern technological materials.

Effect of magneto-rotator-diffusive waves on the photothermal excitation medium of a dual-phase-lag model and variable thermal conductivity

The thermal variable conductivity of a rotator semiconductor elastic medium is investigated. The medium is exposed to beams of light and an initial external magnetic field during a diffusion process. The governing equations cover the overlapping between the wave propagations of mechanical, thermal, plasma and mass diffusion distributions. The reflection wave will be obtained in the context of the thermoelasticity theory and photothermal theory. The harmonic wave analysis is used to obtain the coefficient ratios of reflection analytically of the incident wave (CI) and incident rotational wave. On the free surface of the semiconductor medium, some mechanical, plasma and thermal loads are applied to observe the physical quantities of this phenomenon. The different values of the amplitude of reflection coefficient ratios and the incidence angle are obtained numerically and shown graphically. The comparisons between the obtained results will be studied under the influence of the magnetic field, the variable thermal conductivity and rotation.

Wave propagation in two-temperature generalized thermoelasticity with harmonic wave analysis under thermal shock problem

Wave propagation in two-temperature generalized thermoelasticity with harmonic wave analysis under thermal shock problem

Precipitable water vapor characterization in the coastal regions of China based on ground-based GPS

Water vapor plays an important role in climate change; thus, studying the spatial distribution and temporal variation of precipitable water vapor (PWV) in the coastal regions of China would help researchers to understand the climate characteristics of those regions. In this paper, 6-year 1-h interval PWV were derived from 27 Global Positioning System stations observations of Chinese coastal GPS observation network, surface meteorological data and European Center for Medium-Range Weather Forecasts (ERA-Interim) reanalysis products. The present study provides the use of these data to investigate the spatial-temporal variability of water vapor throughout the coastal regions of China. Latitude is the main factor affecting the spatial distribution of GPS-derived PWV; that is, PWV decreased by about 1.5mm for each 1° increase of latitude. For regions at the same latitude, a region that is relatively close to the ocean will have a higher content of PWV. The PWV in the southeastern and southwestern coastal regions of China is significantly higher in summer; this may be influenced by the southeastern and southwestern water vapor inflow corridors. The PWV obviously varies monthly, reaching a minimum in January; however, the timing of the maximum varied but usually appeared in June, July or August and was affected by the monsoons. The PWV varies largely between summer and winter with a larger gradient of change in PWV with latitude in winter than in summer. The positive correlation coefficient between PWV and the surface temperature varied in different seasons; this is related to the changes of temperature and the horizontal motion of water vapor. Use of the Fast Fourier Transform method showed that the PWV time series data have multi-scale characteristics. The amplitude and phase of the PWV time series in annual, semiannual, four month and seasonal cycles were extracted through harmonic wave analysis. The amplitude of four month and seasonal cycles did not pass significance testing. The maximum amplitude of the annual PWV cycle is located in mid-latitudes with 22.09mm, which gradually decreases towards high latitude and equator area. The peak time of annual PWV cycle occurs in July, which does not agree with the timing of the maximum monthly average PWV. The semiannual cycle amplitudes is between 0.42 and 6.32mm, with no significant correlation between their distribution and latitude. The peak time of semiannual PWV cycles is during about January–March and July–September, and the peak time gradually becomes late from north to south.

Response of a semiconducting infinite medium under two temperature theory with photothermal excitation due to laser pulses

A novel model of two-dimensional deformations for two-temperature theory at the free surface under the excitation of thermoelastic wave by pulsed laser for a semi-infinite semiconducting medium is studied. The effect of mechanical force during a photothermal process is investigated. The mathematical methods of the Lord–Shulman (LS includes one relaxation time) and Green–Lindsay (GL with two relaxation times) theories as well as the classical dynamical coupled theory (CD) are used. An exact expression for displacement components, force stresses, carrier density and distribution of temperature are obtained using the harmonic wave analysis. Combinations of two-temperature and photothermal theories are obtained analytically. Comparisons of the results are made between the three theories also. The effects of thermoelectric coupling parameter, two-temperature parameter on the displacement component, force stress, carrier density, and distribution of temperature for silicon (Si) medium have been illustrated graphically. The variations of the considered variables with the horizontal distance have been discussed.

The elastic wave motions for a photothermal medium of a dual-phase-lag model with an internal heat source and gravitational field

In this work, the dual-phase-lag (DPL) heat transfer model is introduced to study the problem of an isotropic generalized thermoelastic medium with an internal heat source that is moving with a constant speed. Thermal loading at the free surface of a semi-infinite semiconconducting medium coupled plasma waves with the effect of mechanical force during a photothermal process to study the effect of a gravity field. Harmonic wave analysis is used to obtain exact expressions for the considered variables, also the carrier density coefficients were obtained analytically. The variations of the considered variables through the horizontal distance are illustrated graphically under the effects of several parameters based on the DPL model. The results are discussed and depicted graphically.

Error Analysis of Harmonic Measurement Device and Solution

Aiming at the shortage of lowprecision harmonic wave's analysis in China, and the inadaptability of error transmitting, we analyze the error sources and come up with an approach, Direct Data frequency Synthesizer (DDS), to replace the traditional analog Phase Locked Loop (PLL) to track the frequency of measured signal. Non-integer-period Discrete Fourier Transform (DFT) compensation algorithm is used for processing data. Accordingly a high-precision harmonic standard device is designed in this paper. The final test shows that this solution can efficiently improve the precision.

On the use of a viscoelastic split hopkinson pressure bar

To test weak materials such as foams at high strain rates, the use of a Split Hopkinson Pressure Bar (SHPB) setup made of low impedance bars, which are mostly viscoelastic, is indispensable. In this paper a detailed study of the technical problems of such a viscoelastic setup related to the measurement and to the loading conditions is offered. On the basis of the three-dimensional (3D) Fourier stationary harmonic wave analysis, the wave shifting technique is developed. It is shown that the effect of geometrical dispersion in a viscoelastic setup is generally non-negligible. The case of loading with a viscoelastic projectile is also analysed, showing that the impact of a viscoelastic projectile creates an incident wave with a significant time extension.

各種定格高圧水銀ランプ点灯回路の一高調波分析法

各種定格高圧水銀ランプ点灯回路の一高調波分析法

Analysis of harmonic waves in a composite material with piezoelectric effect

The authors are concerned with harmonic waves propagating in a three-dimensional composite, with periodic structure, consisting of anisotroplc. elastic and piezoelectric crystals, obtaining solutions by a mixed variational method. The electric field is treated as quasi-static. The stress, displacement, electric displacement and electric scalar potential are field variables subject to variations in a general variational principle. The matrix-eigenvalue problem is solved to give approximate eigenfrequencics and the corresponding eigcnstates. Numerical examples are given for harmonic waves propagating in the gallium arsenide crystal with ellipsoidal inclusions of lithium niobate.

Seasonal Changes in Density and Tissue Distribution of Onchocerca cervicalis Microfilariae in Ponies and Related Changes in Culicoides variipennis Populations in Louisiana

Seasonal changes in density and spatial distribution of Onchocerca cervicalis microfilariae were studied in ventral-midline skin of 15 infected pony mares in southern Louisiana. Triple running mean analysis of data over a 13-mo period indicated that a distinct pattern exists in total microfilariae population density and in microfilariae occurrence in different levels of the dermis. Microfilariae density reaches peak levels in the spring followed by a 58% decrease in the summer, a 19% increase in the fall, and a decrease to the lowest numbers in the winter. Microfilariae were found in all levels of the skin during the spring, summer, and fall but were not found in the superficial layers of the dermis during the winter months. The population density of Culicoides variipennis, a demonstrated vector of O. cervicalis, appeared to have seasonal fluctuations similar to the changes in microfilarial density. Harmonic wave analysis of microfilariae density data in individual ponies showed that all individuals did not follow the population trend.

Finite Element Analysis of Harmonic Waves in Elastic Composites

Finite Element Analysis of Harmonic Waves in Elastic Composites

Finite element analysis of harmonic waves in layered and fibre‐reinforced composites

AbstractThe problem of harmonic waves in layered and fibre‐reinforced composites is solved by a method of finite elements. Piecewise linear approximating functions are used for the displacement and stress fields in a mixed variational formulation, recently proposed by one of the writers in the form of a new quotient. Numerical computations are made for approximate phase‐velocities of harmonic waves in layered composites, where asymmetric and symmetric triangular meshes, and square meshes with interior nodes, are used. To illustrate the accuracy and effectiveness of the method, these approximate solutions are compared with those given by means of exponential test functions, and the exact ones by Rytov, etc. Calculations are also performed for harmonic waves in fibre‐reinforced composites. Dispersion curves for these waves are obtained and displayed graphically.

Harmonic Waves in a Linear Viscoelastic Plate

The procedure of analysis of harmonic waves propagate in elasticwave guides is applied to harmonic waves in linear viscoelastic wave guides. The formal solutions which satisfy the frequency equations of guides wave motions in a linear viscoelastic plate are thus obtained. The frequency spectra of guided waves in a viscoelastic plate are compared with those of elastic waves, and their differences are discussed. The displacement and the phase lag profiles in L and SV modes are obtained at specific frequencies, and it is shown that the viscoelastic waves of these modes are not plane waves.

BASIC PROPERTIES OF PLANE HARMONIC WAVES IN A PRESTRESSED HEAT-CONDUCTING ELASTIC MATERIAL

This paper is concerned with the propagation of plane harmonic waves of small amplitude in a heat-conducting elastic body of unrestricted symmetry that is not stress free in its undisturbed state. The novelty of the treatment given here consists first in a derivation of the secular equation in a form that makes transparent the association of low- and high-frequency behavior with isentropic and isothermal conditions, and second in the introduction of a multivalent modal function whose regular branches determine the complex slownesses of the possible modes of wave propagation in a given direction. The development of a general analysis of harmonic waves on this basis yields a natural classification of the modes and leads, via a standard result in the theory of algebraic functions, to series representations of modal properties that are valid near the extremes of the frequency range. Attention is subsequently directed to situations in which simplified features of the kind displayed by thermoelastic waves in an initially stress-free isotropic medium are realized. This part of the work is prompted by ideas first evolved in connection with singular surfaces, and the paper concludes with an appraisal of the relationships between harmonic and acceleration waves in the context of thermoelasticity.

Harmonic Wave Analysis of Vibration and Stress in a Longitudinally Reciprocated Bar

The wave equation in one dimension approximately represents the longitudinal motion of a uniform bar that carries regularly spaced equal point masses. Fourier analysis is used to obtain the steady-state solution when the bar is reciprocated from one end. Distributed damping is considered. The more general system of unequal and irregularly spaced point masses on a bar consisting of sections of different mass per unit length is analysed in terms of reflection and transmission coefficients; a wave reflection method and a transfer matrix method are given for the solution of the problem of reciprocation. The limitation of the approximate equation of motion is assessed by examining wave dispersion in the uniform system. Application to ‘traverse bars’ on machines for winding extruded synthetic fibre was the object of the investigation.