Effect Of Thermal Field Research Articles

Theoretical analysis and experimental verification of AZO/i-ZnO/CdS/CIGS multilayer stack isolation using 1064 nm and 355 nm laser wavelengths

This study analyzed the thermal field effect and experimental verification of laser scribing of stainless foil based copper indium gallium selenide solar cells of the AZO/i-ZnO/CdS/CIGS multilayer stack films (P3 layer) using Nd:YAG (1064 nm) and ultraviolet (355 nm) lasers. To prevent breakdown of molybdenum films of the solar cell, the laser processing temperature must be lower than the ablation temperature (2896 °C) of the Mo layer, but higher than the ablation temperature (2248 °C) of aluminum doped zinc oxide layer. Therefore, the scribing depth of the P3 layer is limited to the range 1.5–1.7 μm. First, the ANSYS Parameter Design Language program in the ANSYS finite element software is used to establish the simulation mathematical thermal model of the laser scribing process. To simulate the actual laser scribing process, a three-dimensional FE model for laser scribing process with a moving laser beam was constructed. Comparison the theoretical analysis and experimental results indicated that two sets of simulation parameters could not completely remove the P3 layer when the Nd:YAG laser was used. However, when the UV laser was used, the theoretical and experimental results were in favorable agreement. The findings of this study indicate that simulation analysis results can be helpful as reference data for experimental parameters during the actual scribing process.

Nonlinear low-velocity impact response of functionally graded plate with nonlinear three-parameter elastic foundation in thermal field

Abstract In this paper a nonlinear investigation is presented for impact response of functionally graded material plates which are resting on a nonlinear three-parameter elastic foundation with simply supported end condition. In foundation, the influence of linear Winkler and Pasternak parameter is taken into account. The governing equations of the plate are derived based on a Reddy's higher order shear deformation theory with the von Karman-type of kinematic nonlinearity. The effect of thermal field is considered and material properties of the plates are assumed to be temperature dependent, as well and vary along the thickness according to Voigt model. In addition, by using a modified Hertz's contact law, the influence of material properties of the substrate layers on impact response is considered. The equations of motion are solved via an analytical procedure. The effects of deformation theories as well as thermal field, foundation parameters and impactor's parameters are discussed in results and discussion section.

Analysis of the screw compressor rotors’ non-uniform thermal field effect on transmission error

The vibrational state of the screw compressor is largely dependent on the gearing of the rotors and on the possibility of angular backlash in the gears. The presence of the latter leads to a transmission error and is caused by the need for the downward bias of the actual profile in relation to the theoretical. The loss of contact between rotors and, as a consequence, the current value of the quantity, characterizing the transmission error, is affected by a large number of different factors. In particular, a major influence on the amount of possible movement in the gearing will be exerted by thermal deformations of the rotor and the housing parts in the working mode of the machine. The present work is devoted to the analysis of the thermal state in the operation of the screw oil-flooded compressor and its impact on the transmission error and the possibility of losing contact between them during the operating cycle.

Solidification behavior of high-density polyethylene (HDPE) during injection molding: Correlation between crystallization kinetics and thermal gradient field

This work mainly investigated the effect of thermal field on the crystallization kinetics of high-density polyethylene (HDPE) during injection molding (IM) process. The thickness X = 0.4 was found to be a crucial location heavily influenced by thermal conduction. The temperature decay tended to be stable, with limited variation of the crystallization rate when X > 0.4. It was observed that the crystallization rate was in good proportion to the cooling rate (ϕ). Our experimental finding showed that the consequence of relative crystallinity (χ) was in agreement with that of the secondary temperature difference (STD). This study is practically significant to the further investigation on the relationship among “processing-structure-property” of polymeric materials.

Effect of Thermal Fields on the Shift of Optical Standards of Frequency

Theoretical foundations of the effect of thermal radiation on the resonance shift of an optical clock are briefly described, reasons for the resonance shift are considered, and the behavior of the shift with temperature is investigated. Ways to reduce the effect of thermal radiation on the optical resonance shift is demonstrated by the example of a 87Sr optical clock. Characteristics of thermal imaging systems are calculated to estimate the distribution of the thermal field of the working medium of the optical clock.

Diffusion mechanism of energy flow in multi-heat-source synthesis of SiC

Through the experiments and the numerical simulation of temperature field in multi-heat-source synthesis SiC furnace, in order to research the feature point in multi-heat-source synthesis furnace, the variation law of heat flux was studied and the multi-directional energy flow diffusion mechanism was revealed. The results show that, due to the shielding action between the heat-source and the superposition effect of thermal fields, the insulating effect is best in multi-heat-source synthesis furnace. The heat emission effect is good outside the common area between heat-sources, but the heat storage is poor. Compared with the synthesis furnace that heat source is parallelly arranged, the furnace of stereoscopic arrangement has a more obvious heat stacking effect and better heat preservation effect, but the air permeability of heat source connecting regions is worse. In the case with the same ingredients, the resistance to thermal diffusion and mass diffusion is higher in heat source connecting regions.

The effects of thermal field on radius of curvature interferometric testing

In high accuracy radius of curvature (ROC) measurement, discrepancy may exist in results on the same optical surface under different temperature. In this paper, the effects of temperature on ROC are analyzed systematically including system error of interferometry and thermal self-deformation of spherical optical elements. The self-deformation is simulated by finite element analysis method and experiments are carried out on a set of elements with different ROC, repeatedly measured by interferometry. The result shows that the effects of thermal field on ROC augment with the increasing of radius of measured surface and that the experimental results show consistency with the theoretical analysis, thus demonstrating that the effects on ROC can be estimated and compensated under different temperature variation.

Formation of Multilayer Claddings using High-power Fiber Laser Radiation

Fabricated and investigated samples of multilayer cladding on the flat surface are obtained using a laser cladding technology. Iron-based powder was used in the study. Geometric parameters of track depending on the process parameters were determined. The effect of thermal fields on the quality of the coating was analyzed. Optimal strategy areas adjacent to tracks and each subsequent layer deposition have been identified. Microhardness of the resulting coatings was measured. Result of this work is a multi-layer coating in order to restore and improve the surfaces of parts, which exposed to wear.

Modeling the Effect of Thermal Field in Formation of Magnetic Flux Avalanches in Hard Superconductors

Magnetothermal instabilities are one of the uncharacteristic phenomena of interest in conventional type-II as well as in high-T c superconductors. Historically, some authors undertake to analyze the nature and origin of the magnetothermal instabilities of the critical state and flux jumps phenomena in superconductors in the light of theoretical and experimental results (Wipf, Phys. Rev. 161:404, 1967; Wipf, Cryogenics 31:936, 1992; Lee at al., J. Appl. Phys. 107:013902, 2010) [1, 2]. In contrast to previous reported works which had studied the magnetic flux avalanches in hard superconductors postulating an instability criterion, in this paper, we report the development of a theoretical model for describing the magnetization curves of type-II superconductors considering the fact that the jumps should arise naturally, i.e., without the need to impose a priori conditions of instability. The model developed is applied to make numerical calculations in order to get magnetization curves of MgB2 as well as to calculate and analyze the impact of changes in the thermal field and functions that describe the critical current. We investigate the effect of initial magnetic state on generation of magnetic flux avalanches. The initial state determines the evolution of the magnetization curves and their jumps. The results obtained with the application of this model allow us to reproduce the experimental conditions with greater accuracy than that achieved with models based on unstable conditions; further, the model predicts the impact of initial nonzero fields in the formation of avalanches.

Geometrically non-linear transient thermo-elastic response of FG beams integrated with a pair of FG piezoelectric sensors

This paper deals with the geometrically non-linear static and dynamic analysis of functionally graded (FG) beams under combined effect of thermal fields and mechanical excitations integrated with a pair of sensor layers for structural monitoring. The sensor layers are considered to be made of the functionally graded piezoelectric (FGP) materials. The material properties of the host FG beam and FGP sensors are assumed to be graded in the thickness direction according to a power law distribution. The von Karman type geometric non-linearity and the first-order shear deformation theory are used to formulate the governing equations of motion utilizing the Hamilton principle. The solution of coupled non-linear partial differential equations in spatial and time domains is obtained using the hybrid generalized differential quadrature method–Newmark algorithm–Newton–Raphson iterative scheme. A set of parametric study is conducted to show the influence of geometric non-linearity, material parameters and temperature field on the static and dynamic responses of piezoelectric FG beams subjected to impulsive loads. Due to the absence of similar results in the specialized literature, it is expected that the results of this research will be instrumental toward an optimal design of piezoelectric FG structures for static and dynamic structural health monitoring purpose.

Superionic Conductivity and Specific Effects Induced by γ-Radiation in Nanofibrous TlGaTe2 Crystals

Temperature dependences of electrical conductivity (T), switching effect, THz spectra and permittivity e(T) of onedimensional (1D) TlGaTe2 single crystals are investigated. The superionic conductivity observed at temperatures above 305 K is related to diffusion of Tl+ ions via vacancies in the thallium sublattice between   2 2 3 Te Ga nanochains. A relaxation character of dielectric anomalies suggests the existence of electric charges weakly bound to the crystal lattice. Upon the transition to the superionic state, relaxors in the TlGaTe2 crystals are Tl+ dipoles ((   2 2 3 Te Ga ) nanochains) that arise due to melting of the thallium sublattice and hops of Tl+ ions from one localized state to another. The effect of a fieldinduced transition of the TlGaTe2 crystal to the superionic state is detected. The temperature dependences of σ(T) and currentvoltage characteristics subjected to various doses of γradiation in both geometries of the experiment, along nanochains parallel to the tetragonal axis of the crystal σ) and perpendicular to these nanochains, are studied. It is shown that the dependence σ(T) measured in the ohmic region of the current-voltage characteristic is the shape typical of the hopping mechanism. The current-voltage characteristics in the region of a more abrupt increase in the current are also studied and explained in the context of the Pool-Frenkel thermal-field effect. It is shown that anisotropy of electrical conductivity changes under the effect of irradiation, which brings about translational ordering of nanochains. Terahertz time-domain spectroscopy reveals absorption lines at approximately 0.2 THz that may be attributed to the libration oscillations of the nanofibers in the superionic phase.

Non-Linear Response of Functionally Graded Cylindrical Shells under Mechanical and Thermal Loads

Considering rotary in-plane inertias, the geometrically non-linear vibrations of the functionally graded cylindrical shells under the combined effect of thermal fields and mechanical excitations are analysed by using the von Kármán non-linear theory. The coupled non-linear partial differential equations are discretized based on a series expansion of linear modes and a multiterm Galerkin's method. The non-linear equation of motion is then solved by the fourth-order Runge-Kutta numerical method. Parametric studies are carried out in order to study the influence of temperature change, volume fraction exponent of functionally graded materials and the geometry parameters on the non-linear dynamic response of the functionally graded cylindrical shells.

Electrical properties of thin-film composites based on silicon and polypropylene

Results of a study of the current-voltage characteristics of composite resistors (varistors) based on nonpolar propylene and single-crystal silicon are presented. It is shown that the portion of a sharper increase in the current-voltage characteristic is described within the Pool-Frenkel thermal-field effect. It is found that ionized center concentrations N t increase (1.7–16) × 1022 m−3, carrier free path lengths decrease (4–1.9) × 10−8 m, and potential well heights decrease with increasing filler percentage.

Investigation on transmission parameters of vibration measurement on high temperature environment

Temperature rise can lead to signal transmission change of vibration measurement during test run of engines. In the article, the effect of thermal field on electromagnetic field variables was studied. Combining test transmission network, a new approach is proposed to extract multiconductor transmission parameters. The parameters values obtained by proposed approach are in good agreement with classical energy method. It can be shown that resistance and inductance of transmission conductor increase with the rising temperature, and conductor resistance has obvious change range as compared to inductance. Temperature rise aggravates proximate effects of conductors, and mutual electrical parameters have important changes due to temperature and distance. All the change of resistance and inductance can bring more effect on final signal procession.

Specific features of conductivity of γ-irradiated TlGaTe2 crystals with nanochain structure

Temperature dependences of electrical conductivity σ(T) and current-voltage characteristics of one-dimensional TlGaTe2 single crystals subjected to various doses of γ-ray radiation in both geometries of the experiment-along nanochains parallel to the tetragonal axis of the crystal (σ|) and perpendicular to these nanochains (σ⊥)-are studied. It is shown that the dependence σ(T) measured in the ohmic region of the current-voltage characteristic is the shape typical of the hopping mechanism and can be described in terms of the Mott approximation. The values of the densities of localized states NF, the activation energy Ea, the hop lengths R, the difference between the energies of states ΔE in the vicinity of the Fermi level, and the concentrations of deep traps Nt are determined. The current-voltage characteristics in the region of a more abrupt increase in the current are also studied. It is shown that this region of current-voltage characteristics is described in the context of the Pool-Frenkel thermal-field effect. Concentrations of ionized centers Nf, the free-path lengths λ, the Frenkel coefficients β, and the shape of the potential well in initial and irradiated (with 250 Mrad) TlGaTe2 crystals are determined. It is shown that anisotropy of electrical conductivity changes under the effect of irradiation, which brings about translational ordering of nanochains.

Thermal control of electroosmotic flow in a microchannel through temperature-dependent properties

A numerical investigation is conducted on the electroosmotic flow and associated heat transfer in a two-dimensional microchannel. The objective of this study is to explore a new conceptual idea that is control of an electroosmotic flow by using a thermal field effect through the temperature-dependent physical properties. Two exemplary problems are examined: a flow in a microchannel with a constant vertical temperature difference between two horizontal walls and a flow in a microchannel with the wall temperatures varying horizontally in a sinusoidal manner. The results of numerical computations showed that a proper control of thermal field may be a viable means to manipulate various non-plug-like flow patterns. A constant vertical temperature difference across the channel produces a shear flow. The horizontally-varying thermal condition results in spatial variation of physical properties to generate fluctuating flow patterns. The temperature variation at the wall with alternating vertical temperature gradient induces a wavy flow.

Scheme for Generalized Quantum State Sharing of a Single-Qubit State in Cavity QED

An experimentally feasible scheme for generalized quantum state sharing of an arbitrary unknown single-qubit state in cavity QED is presented. Using a generalized Greenberger–Horne–Zeilinger (GHZ) state as the quantum channel among the three parties, the quantum information (i.e. the single-qubit state) from the sender can be split in such a way that the information can be recovered if and only if both receivers collaborate. Moreover, the scheme is insensitive to both the effects of thermal field and cavity decay.

Teleportation of an Arbitrary Two-Atom EntangledState via Thermal Cavity

We present an experimentally feasible scheme forteleportation of an arbitrary unknown two-atom entangledstate by using two-atom Bell states in driven thermal cavities. Inthis scheme, the effects of thermal field and cavity decay can beall eliminated. Moreover, the present scheme is feasible according tocurrent technologies.

Frenkel thermal-field effect in MnGaInS4 layered single crystals

The I–V characteristics are investigated in the region of high electric fields in MnGaInS4 single crystals. It is shown that the current in the nonlinear portion of the I–V characteristic is caused by the Frenkel thermal-field effect. The permittivity, trap concentration, and potential-well shape are determined.

Thermally induced transitions to chaos in plate vibrations

The geometrically nonlinear vibrations of linear elastic and isotropic plates under the combined effect of thermal fields and mechanical excitations are analysed. With this purpose, a model based on a p-version, hierarchical, first-order shear deformation finite element is employed. The equations of motion are solved in the time domain by Newmark's implicit time integration method. The temperature and the amplitude of the mechanical excitation are varied, and transitions from periodic to non-periodic motions are found.