Effect of Thermal Relaxation on Propagation of Longitudinal Displacement Wave

2010 ◽  
Vol 146-147 ◽  
pp. 314-317
Author(s):  
Bing Bing Xue ◽  
Hong Yu Xu ◽  
Zhu Mu Fu ◽  
Qing Yong Sun
Keyword(s):  
Relaxation Times ◽  
Thermal Relaxation ◽  
Theory Model ◽  
Longitudinal Displacement ◽  
Amplitude Ratios ◽  
Reflection And Refraction ◽  
Thermal Relaxation Times ◽  
Displacement Wave ◽  
Viscoelastic Theory ◽  
Coupled Theory

The micropolar elasticity theory takes into consideration the granular character of the medium, describes deformations by a microrotation and a microdisplacement. A model can be applied to the coupled theory as well as to five generalizations, such as L-S theory, G-L theory, H-I theory, G-N theory of type (II) and C-T theory. And if some parameters in this model are taken as given values, we can easily deduce the known models of Kelvin-Voigt model and other generalized micropolar/magneto/thermo/viscoelastic theory model. Employing the model of micropolar generalized magneto-thermo-elasticity, reflection and refraction of longitudinal displacement wave at interface of two welded micropolar elastic media are studied. The amplitude ratios of reflected and refracted micropolar magneto-thermoelastic longitudinal displacement waves, longitudinal microrotational waves and the coupled transverse and microrotational waves are studied for incident longitudinal displacement wave. The numerical results show that the effects of thermal relaxation times are very significant on the amplitude ratios.

Reflection and Refraction of Longitudinal Displacement Wave at Interface between Two Micropolar Elastic Solid

2010 ◽  
Vol 139-141 ◽  
pp. 214-217 ◽  
Author(s):  
Bing Bing Xue ◽  
Hong Yu Xu ◽  
Zhu Mu Fu ◽  
Qing Yong Sun
Keyword(s):  
Elastic Solid ◽  
Theory Model ◽  
Type Ii ◽  
Longitudinal Displacement ◽  
Amplitude Ratios ◽  
Reflection And Refraction ◽  
Displacement Wave ◽  
Viscoelastic Theory ◽  
Voigt Model ◽  
Coupled Theory

Using the model of generalized micropolar magneto-thermo-elasticity, reflection and refraction of longitudinal displacement wave at interface of two welded micropolar elastic media are studied. The model can be applied to the coupled theory as well as to five generalizations, such as L-S theory, G-L theory, H-I theory, G-N theory of type (II) and C-T theory. And if some parameters in this model are taken as given values, we can easily deduce the known models of Kelvin-Voigt model and other generalized micropolar/magneto/thermo/viscoelastic theory model. Using continuous conditions at the interface, the amplitude ratios of reflected and refracted micropolar magneto-thermoelastic longitudinal displacement waves, longitudinal microrotational waves and the coupled transverse and microrotational waves are studied for incident longitudinal displacement wave. The numerical results show that the effect of magnetic field is very significant on the amplitude ratios.

Reflection and Refraction of Coupled Transverse and Micro-Rotational Wave at Interface between Two Micropolar Elastic Solid

2013 ◽  
Vol 670 ◽  
pp. 193-201 ◽  
Author(s):  
Hong Yu Xu ◽  
B.B. Xue ◽  
F.K. Cui ◽  
X.Q. Wang
Keyword(s):  
Relaxation Times ◽  
Thermal Relaxation ◽  
Elastic Solid ◽  
Phase Lag ◽  
Amplitude Ratios ◽  
Reflection And Refraction ◽  
Rotational Wave ◽  
Thermal Relaxation Times ◽  
Without Energy Dissipation ◽  
Rotational Waves

Using the model of micropolar generalized magneto-thermo-elasticity, the coupled transverse and micro-rotational wave at an interface between two micropolar solid mediums is discussed in the presence of a constant magnetic field. The model can be applied to the coupled theory as well as to five generalizations: the Lord-Shulman theory with one relaxation time, the Green-Lindsay theory with two relaxation times, the Green-Naghdi theories of type II(without energy dissipation) and of type III, and the theory with dual-phase-lag. Using continuous conditions at the interface, the amplitude ratios of reflected and refracted longitudinal displacement waves, longitudinal micro-rotational waves and the coupled transverse and micro-rotational waves are studied for incident coupled transverse and micro-rotational wave. The effect of thermal relaxation is discussed for C-D theory, G-L theory and L-S theory. The numerical results show that the effects of thermal relaxation times are very significant on the amplitude ratios.

Theory of Ultrasonic Thermal Relaxation Times in Liquids

1957 ◽  
Vol 26 (3) ◽  
pp. 469-473 ◽  
Author(s):  
Theodore A. Litovitz
Keyword(s):  
Relaxation Times ◽  
Thermal Relaxation ◽  
Thermal Relaxation Times

Analysis of Deep Levels in GaAs Detector Diodes Using Impedance Spectroscopy

1993 ◽  
Vol 302 ◽  
Author(s):  
C Eiche ◽  
M Fiederle ◽  
J Weese ◽  
D Maier ◽  
D Ebling ◽  
...  
Keyword(s):  
Cross Section ◽  
Regularization Method ◽  
Capture Cross Section ◽  
Relaxation Times ◽  
Thermal Relaxation ◽  
Simulated Data ◽  
Deep Levels ◽  
Admittance Spectroscopy ◽  
Thermal Relaxation Times ◽  
Level 2

ABSTRACTImpedance or admittance spectroscopy has been shown to be a very convenient tool for the investigation of deep levels in semiconductor junctions. At constant temperature a frequency sweep is performed. After that the impedance signal is analysed by a regularization method based on Tikhonov regularization in order to obtain the thermal relaxation times of the deep levels present in the junction. The high resolution of the regularization method in comparison to conventional techniques is demonstrated using simulated data. The temperature dependence of the thermal relaxation times provides information about the properties of the deep levels such as activation energy or capture cross section. Two donor levels with activation energies dE1 =0.58 eV and dE2 =0.68 eV are observed in our detector diodes. It can be shown that the concentration of level 2 is increased after irradiation.

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