Thermoelastoplastic Deformation Analysis of Electromechanical Equipments under Electrocaloric Shock

A coupled thermomechanical model is presented to investigate the thermoelastoplastic deformation mechanism of electromechanical equipments under the condition of electrocaloric shock. In the coupling model, differentiating from the previous analyzing viewpoint that looked upon deformation work as additional heat source, temperature- field equation is established by considering the weakening role of deformation work on the intensity of internal heat source; in the process of setting up displacement-field equation, G-derivative of nonlinear functional is introduced into the traditional theory of elastoplastic finite deformation to simplify the expression of structural stiffness; stress-field equation is constructed by using the least square method to improve the stress solution obtained by constitutive equation. The presented model is converted into finite element program to simulate deforming process of 3-D structures with temperature-dependent material properties. As an example, thermal deformation analysis of Shanghai metro cars＇ brake resistor is performed and compared with experimental results for illustrating the validity of the presented model.     

Local orthogonal transform for a class of acoustic waveguides

There are some curved interfaces in acoustic waveguides. To compute wave propagation along the waveguides with some marching methods, flattening of the internal interfaces is needed. In this paper, a local orthogonal coordinate transform and an equation transform are constructed to solve the two-dimensional Helmholtz equation for the waveguides bounded by a flat top, a flat bottom and two curved internal interfaces with three layered media. The curved internal interfaces are flattened by the local orthogonal coordinate transform, and the corresponding transformed Helmholtz equation can be solved by some marching methods. This treatment can be extended in multilayered medium waveguides. The one-way reformulation based on the Dirichlet-to-Neumann (DtN) map is then used to reduce the boundary value problem to an initial value problem. Numerical implementation of the resulting operator Riccati equation uses a large range step method to discretize the range variable and a truncated local eigenfunction expansion to approximate the operators. This method is particularly useful for solving long range wave propagation problems in slowly varying waveguides with multilayered medium structure.     

Atomistic structural change of silicon surface under a nanoparticle collision

As the dimensions of the semiconductor device com-ponents shrink, a profound understanding of the mi-cro/nanomachining of monocrystalline silicon surface isbecoming essential. Molecular dynamics (MD) simulationis a powerful tool for the study of the processing mecha-nism of silicon surfaces. The MD simulations of nano-cutting[1,2], nano-grinding[3,4], as well as nano-indenta-tion[5,6] have been studied intensively. It is shown that theamorphous phase transformation and the plastic flow in-si…     

Dynamics of a qubit—TLS system under resonant microwave driving

We demonstrate the effect of different coupling strengths between a microscopic two-level system(TLS)and a microwave field on the dynamics of a qubit—TLS system when the bipartite system is subject to resonant microwave driving.Rabi beating with a different TLSmicrowave coupling strength is demonstrated in simulations.Entanglement,quantified by the concurrence between the qubit and TLS,both for pure states and mixed states,is simulated.When decoherence is considered,entanglement of the bipartite system oscillates with damping and exhibits entanglement sudden death and/or entanglement sudden death and revival.     

Surface Phase Diagrams of the Site-bond Diluted Surface Ordering an Ising Ferromagnet with a Transverse Field

■i■hin the framework of an effeetive-fieId theory with correlation we diseuss the phase diagrams for surface ordering in a semi-infinite Jsing ferromagnet with a site-bond diluted free surface and a transverse field. A certain characteristic behaviour for the surface ordering is obtained.     

Analytical Results of Server Loads and Network Load in a General Client／Server System

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Simulation Studies on the Probability of Fibers Passing Through a Circular Bond Point in Point-Bonded Nonwovens

It is very important to get the tensile properties of bridgefiber bundles between bond points in the simulation stud-ies on the tensile properties of point - bonded nonwov-ens. In order to construct models to predict the tensileproperties of bridge fiber bundles, it is essential to inves-tigate the number of fibers passing through certain bondpoints. The probability of fibers passing through bondpoints in nonwovens is investigated. A tentative proba-bility formula that includes the factors such as specimensize, fiber length and bond point radius, and a formulato calculate the number of fibers passing through bondpoints are proposed on the basis of the data of the simu-lations.     

A kinetic study of the reaction of ozone with ethylene in a smog chamber under atmospheric conditions

Ozone is one of the key species in the processes of atmospheric chemistry, which can be taken as an indicator of oxidation capacity in the troposphere. The reaction of ozone with reactive gases is an important process in the troposphere. Experimental simulation equipment of smog chamber for atmospheric reactions is used to study the reaction of ozone with ethylene in real atmospheric environment with ozone concentrations of 100―200 ppb. The concentrations of ozone and ethylene were moni-tored during the reaction with the combination of Model 49C-O_3 Analyzer and GC-FID. A rate constant of 1.01×10~(-18) (cm~3·mol~(-1)·s-(~1)) was obtained at 286.5 K, under condition of which the half-life of ozone was 88 min. The results obtained from our experiments are in excellent agreement with those reported previously by other researchers under extremely low pressure in terms of matrixisolation technology. This demonstrates that our equipment of smog chamber for atmospheric reactions is reliable, which can be used for further research of the processes of atmospheric reactions.     

Status quo of English Teaching and Learning in a Local County Senior High School in China

The past two decades witnessed great changes in therealm of English teaching. Language teaching theorists haveshifted their focus of attention from teaching to learning,tryingto give a central position to the learners,rather than the teacherby advocating ideas like humanistic language teaching andlearner autonomy etcetera. And developments in languageteaching theory itself have already demonstrated their influenceupon policy makers,having led to formulation and nationwideadoption of more human…     

刚塑性圆管经受侧向撞击时变形与损伤的研究

通过对圆管侧向撞击实验，证实变形包括撞击处的局部变形和圆管的整体弯曲，采用刚塑性假定，分别得出了两种变形的计算模式，其计算值与实验值吻合得较好，借此可以预测圆管遭遇侧向撞击后的损伤程度。