New simple exact penalty function for constrained minimization

By adding one variable to the equality-or inequality-constrained minimization problems, a new simple penalty function is proposed. It is proved to be exact in the sense that under mild assumptions, the local minimizers of this penalty function are precisely the local minimizers of the original problem, when the penalty parameter is sufficiently large.     

Interlayer shear strength of single crystalline graphite

Reported values(0.2 MPa-7.0 GPa) of the interlayer shear strength(ISS) of graphite are very dispersed.The main challenge to obtain a reliable value of the ISS using conventional measuring methods was the unavailability of sufficiently large single crystalline graphite.Here we present a novel experimental method to measure the ISS,and obtain the value as ～0.14 GPa.Our result can serve as an important basis for understanding mechanical behavior of graphite or graphene-based materials.     

Thermoelastic stress analysis of multilayered films in a micro-thermoelectric cooling device

This paper presents an analytical solution for the thermoelastic stress in a typical in-plane’s thin-film micro-thermoelectric cooling device under different operating conditions. The distributions of the permissible temperature fields in multilayered thin-films are analytically obtained, and the characteristics, including maximum temperature difference and maximum refrigerating output of the thermoelectric device, are discussed for two operating conditions. Analytical expressions of the thermoelastic stresses in the layered thermoelectric thin-films induced by the temperature difference are formulated based on the theory of multilayer system. The results demonstrate that, the geometric dimension is a significant factor which remarkably affects the thermoelastic stresses. The stress distributions in layers of semiconductor thermoelements, insulating and supporting membrane show distinctly different features. The present work may profitably guide the optimization design of high-efficiency micro-thermoelectric cooling devices.     

SINGLE AND DOUBLE EDGE INTERFACE CRACK SOLUTIONS FOR ARBITRARY FORMS OF MATERIAL COMBINATION

In this paper interfacial edge crack problems are considered by the application of the finite element method. The stress intensity factors are accurately determined from the ratio of crack-tip-stress value between the target given unknown and reference problems. The reference problem is chosen to produce the singular stress fields proportional to those of the given unknown problem. Here the original proportional method is improved through utilizing very refined meshes and post-processing technique of linear extrapolation. The results for a double-edge interface crack in a bonded strip are newly obtained and compared with those of a single-edge interface crack for different forms of combination of material. It is found that the stress intensity factors should be compared in the three different zones of relative crack lengths. Different from the case of a cracked homogeneous strip, the results for the double edge interface cracks are found to possibly be bigger than those for a single edge interface crack under the same relative crack length.     

DETERMINATION OF QUADRICEPS FORCES IN SQUAT AND ITS APPLICATION IN CONTACT PRESSURE ANALYSIS OF KNEE JOINT

While the quadriceps muscles of human body are quite important to the daily activities of knee joints,the determination of quadriceps forces poses significant challenges since it cannot be measured in ...     

Finite time chaos control for a class of chaotic systems with input nonlinearities via TSM scheme

This paper investigates nonsingular terminal sliding mode control for a class of uncertain systems with nonlinear inputs and its application in chaos control. When some of the system states are finite-time stable, the nonlinear items that coupled with these states may come into zeros in other subsystems. This will simplify the stability analysis of the whole system greatly. Compared with the traditional finite-time stabilization design method, the introduction of the terminal sliding mode can reduce the input dimensions. Only one control input is requested to realize chaos control of the Liu system when unmatched uncertainties and input nonlinearity coexist. The parameter matrices in the TSM can be determined through the solution of LMIS. Simulation results are given to demonstrate the effectiveness of the proposed method.     

Correlated scale-free network with community: modeling and transportation dynamics

Many transport processes on network depend crucially on the underlying network topology. In this paper, we propose a model to generate correlated scale free transportation networks with community structure by considering the mechanisms of dynamical network evolution and rewiring links. With the introduction of congestion effects, we investigate the performance and carrying capacity of this network. The results show that congestion in the uncorrelated network is more serious than the assortative or disassortative ones. Therefore, the correlated network with communities can bear much more traffic flow. In addition, the networks with lager modularity can enhance the transportation efficiently.     

Chaotic ant swarm optimization with passive congregation

Chaotic ant swarm optimization (CASO) is a powerful chaos search algorithm for optimization problems, but it is often easy to be premature convergence. To overcome the weakness, this paper presents a CASO with passive congregation (CASOPC). Passive congregation is one type of biological information sharing mechanisms that allow animals to aggregate into groups and help to enhance the exploitation of animals. By introducing passive congregation strategy into the CASO, a modified evolution equation based on the CASO is proposed in the CASOPC. The modified evolution equation cannot only employ the parallel search of all ants and the well exploration ability of the CASO, but also stress and control the exploitation by passive congregation coefficient c in the stage of evolution. Due to linearly increasing c in the CASOPC, the exploration and exploitation ability of ants are well balanced so that premature convergence can be avoided and good performance can be achieved. In order to estimate the capability of the CASOPC, it is tested with a set of 5 benchmark functions with 30 dimensions and compared to the CASO. Experimental results indicate that the CASOPC improves the search performance on the benchmark functions significantly.     

Stability and bifurcation periodic solutions in a Lotka–Volterra competition system with multiple delays

This paper is concerned with a Lotka?CVolterra competition system with multiple delays. Firstly, we investigate the existence and stability of the positive equilibrium. In particular, we find that the system has Hopf bifurcation at the positive equilibrium, whereas this singularity does not occur for the corresponding system with two delays when interspecies competition is weaker than intraspecies competition. Secondly, we analyze the stability of the periodic solutions by reducing the original system on the center manifold. Finally, some numerical examples are given to verify our theoretical results.     

Research on the price game model for four oligarchs with different decision rules and its chaos control

Based on the actual competition in the Chinese property insurance market, the repeated price game model for four oligarchs with different decision rules is built. On the basis of analyzing the stabilities of eight fixed points about the four-dimensional dynamic system, the Nash equilibrium and its local stable region are discussed mainly. Then the complexity of the four-dimensional discrete dynamic system and its evolutionary process are studied. Finally, the delay feedback control method is used to control the chaos. Numerical simulation results have shown that the influence which the change of price adjustment speed has on the movement of dynamic system has a sensitive dependence on the initial conditions, and there is a strong connection between the profit of each oligarch and the price adjustment speed or the control parameters, and the corresponding economic explanation to those phenomena will have important reference values to the realistic problems.