scholarly journals Generalized Thermopiezoelectricity with Memory-Dependent Derivative and Transient Thermoelectromechanical Responses Analysis

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Jianzhong Sun ◽  
Yaping Wu
Keyword(s):  
Time Delay ◽  
Kernel Function ◽  
Piezoelectric Materials ◽  
Piezoelectric Medium ◽  
Transient Responses ◽  
New Approach ◽  
Practical Applications ◽  
Parametric Studies ◽  
Heating Loads ◽  
With Memory

In this paper, a novel generalized thermoelastopiezoelectric model is established by introducing memory-dependent derivative, which might be superior to fractional ones: the form is unique, while the fractional-order theories have various expressions with different authors; it is more intuitionistic for reflecting the memory effect; the physical meanings of the related memory-dependent differential equations are more clear, which are determined by the essence of their definitions; the time-delay and kernel function can be chosen freely based on the necessity of practical applications. The newly constructed model is applied to the transient shock analysis for piezoelectric medium under heating loads. Laplace transformation techniques are employed to solve the governing equations. In numerical implementation, the problem of a semi-infinite piezoelectric medium is considered under the two different cases. The transient responses, that is, temperature, displacement, stress, and electric potential, are illustrated graphically. The parametric studies are performed to analyze the effects of time-delay and kernel function on the transient thermoelastopiezoelectric responses. This work may provide a new approach to explore the transient responses’ behavior for piezoelectric materials serving in nonisothermal environment.

Transient responses of sandwich structure based on the generalized thermoelastic diffusion theory with memory-dependent derivative

2018 ◽  
Vol 22 (8) ◽  
pp. 2505-2543 ◽  
Author(s):  
Tianhu He ◽  
Yan Li
Keyword(s):  
Time Delay ◽  
Sandwich Structure ◽  
Chemical Potential ◽  
Diffusion Theory ◽  
Kernel Functions ◽  
Characteristic Parameters ◽  
Material Characteristic ◽  
Transient Responses ◽  
Thermoelastic Diffusion ◽  
With Memory

The present work is devoted to investigating the transient responses of a sandwich structure based on the generalized thermoelastic diffusion theory with memory-dependent derivative. Both the left and the right bounding surfaces are subjected to a thermal shock and a chemical potential shock simultaneously. It is assumed that the values of thermal contact resistance and diffusional contact impedance at the interface are zero with ideal adhesion. The coupled governing equations containing time delay factors and kernel functions, which can be chosen freely according to specific problems, are solved by the Laplace transform together with its numerical inversion. The influences of the material characteristic parameters at the interface on the structural responses are emphatically discussed, and the non-dimensional temperature, chemical potential, displacement, stress as well as concentration at different values of time delay factors and kernel functions are obtained and illustrated graphically. The results show that: the changes of the time delay factors, kernel functions, and material characteristic parameters have the varying degrees of influences on the considered variables. Based on the above conclusions, the sandwich structure working under the thermoelastic diffusion coupling condition can be designed reasonably.

Thermo-Electro-Mechanical Behavior of Finite Piezocomposites Cylinder

2013 ◽  
Vol 740 ◽  
pp. 368-373
Author(s):  
P. Boonphennimit ◽  
J. Rungamornrat ◽  
T. Senjuntichai
Keyword(s):  
Analytical Solution ◽  
Curve Surface ◽  
Transversely Isotropic ◽  
Piezoelectric Medium ◽  
Composite Cylinder ◽  
Governing Equations ◽  
Transient Responses ◽  
Practical Applications ◽  
Mechanical Field ◽  
Fundamental Understanding

This paper presents a complete analytical solution for transient responses of a transversely isotropic thermopiezoelectric finite composite cylinder under axisymmetric boundary conditions. The governing equations for coupled axisymmetric electro-thermo-mechanical field of a transversely isotropic piezoelectric medium are employed, and the corresponding general solutions are derived. A boundary-value problem corresponding to composites of finite thermopiezoelectric cylinder with axisymmetric mechanical and electrical loadings applied at the curve surface of a cylinder is solved. The solutions presented in this study can provide fundamental understanding of thermo-electro-mechanical behaviour of thermopiezoelectric finite composite cylinder under various loading conditions, and are useful for the development of piezocomposites for practical applications.

Control of multi-scroll attractors in a memristor-coupled resonator via time-delayed feedback

2018 ◽  
Vol 32 (32) ◽  
pp. 1850399 ◽  
Author(s):  
Zhilong Liu ◽  
Fuqiang Wu ◽  
Faris Alzahrani ◽  
Jun Ma
Keyword(s):  
Dynamical System ◽  
Time Delay ◽  
Magnetic Flux ◽  
Memory Effect ◽  
Delayed Feedback ◽  
Feedback Gain ◽  
Initial Setting ◽  
Physical Background ◽  
Time Delayed Feedback ◽  
With Memory

A four-variable dynamical system composed of memristor is proposed to investigate the dependence of multi-scroll attractor on initial setting for one variable with memory, and the description for physical background is supplied. It is found that appropriate setting of initial values for the memory variable can induce different numbers of attractor, as a result, resetting initials can change the profile of attractors which is also dependent on the calculating period. Time-delayed feedback is used to stabilize the dynamical system thus the effect of initial dependence is suppressed and multi-scroll attractors are controlled by applying appropriate time delay and feedback gain in the controller. Furthermore, the system is verified on FPGA circuit platform and memristor is used to describe the memory effect of variable related to magnetic flux. It is confirmed that multi-scroll attractors can be stabilized and the dependence of initials setting is suppressed in experiment way.

Enhanced fatigue resistance and lattice dynamics induced by the strong local strain in Fe-doped KTa1-xNbxO3 single crystal

2021 ◽  
Author(s):  
Xiaolin Huang ◽  
Peng Tan ◽  
Yu Wang ◽  
Yao Zhang ◽  
Xiangda Meng ◽  
...  
Keyword(s):  
Single Crystal ◽  
Fatigue Resistance ◽  
Lattice Dynamics ◽  
Piezoelectric Materials ◽  
Local Strain ◽  
Lead Free ◽  
Fatigue Properties ◽  
Practical Applications ◽  
Local Structures ◽  
The Impact

Improvement of durability is greatly important for the practical applications of lead-free-doped piezoelectric materials. However, the promotional mechanism of anti-fatigue properties and the impact on local structures from ion dopants...

scholarly journals Latent likelihood ratio tests for assessing spatial kernels in epidemic models

2020 ◽  
Vol 81 (3) ◽  
pp. 853-873
Author(s):  
David Thong ◽  
George Streftaris ◽  
Gavin J. Gibson
Keyword(s):  
Likelihood Ratio ◽  
Kernel Function ◽  
Control Strategies ◽  
Spatial Separation ◽  
Likelihood Ratio Tests ◽  
New Approach ◽  
Competing Models ◽  
Spatio Temporal ◽  
Fully Bayesian ◽  
The Relationship

Abstract One of the most important issues in the critical assessment of spatio-temporal stochastic models for epidemics is the selection of the transmission kernel used to represent the relationship between infectious challenge and spatial separation of infected and susceptible hosts. As the design of control strategies is often based on an assessment of the distance over which transmission can realistically occur and estimation of this distance is very sensitive to the choice of kernel function, it is important that models used to inform control strategies can be scrutinised in the light of observation in order to elicit possible evidence against the selected kernel function. While a range of approaches to model criticism is in existence, the field remains one in which the need for further research is recognised. In this paper, building on earlier contributions by the authors, we introduce a new approach to assessing the validity of spatial kernels—the latent likelihood ratio tests—which use likelihood-based discrepancy variables that can be used to compare the fit of competing models, and compare the capacity of this approach to detect model mis-specification with that of tests based on the use of infection-link residuals. We demonstrate that the new approach can be used to formulate tests with greater power than infection-link residuals to detect kernel mis-specification particularly when the degree of mis-specification is modest. This new tests avoid the use of a fully Bayesian approach which may introduce undesirable complications related to computational complexity and prior sensitivity.

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