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Nanchang, China

Nanchang Hangkong University , also Nanchang Aviation University, is located in Nanchang City, Jiangxi Province, People's Republic of China. It is an engineering-based multidisciplinary university.NCHU now has over 1,200 professional teachers. At present, the total number of registered students is 21,000, of whom 19,000 undergraduates, 1,095 postgraduates, and over 1,200 vocational students. NCHU gives first priority to the all-around development of students as well as the quality of education, and directs its efforts to teaching innovations. As a result, it has made great achievements in the cultivation of talents and its employment rate of graduate ranks first in Jiangxi Province. Wikipedia.

In this paper, a solution to the problem of finding the shape of piezoelectric modal sensors for non-uniform EulerBernoulli beams with rectangular cross-sections is proposed by using the differential transformation method (DTM). A general expression for designing the shape of a piezoelectric modal sensor is presented, in which the output signal of the designed sensor is proportional to the response of the target mode. The modal sensor shape is expressed as a linear function of the second spatial derivative of the structural mode shape function as well as the beam width and thickness function. Based on the DTM and employing some simple mathematical operations, the closed-form series solution of the second spatial derivative of the mode shapes for beams consisting of an arbitrary number of steps can be determined through a recursive way. The solution is obtained by solving a set of algebraic equations with only five unknown parameters. Furthermore, the method can be extended to obtain an approximate solution of the second spatial derivative of the mode shapes for any type of non-uniform beams. Then the shapes of the piezoelectric modal sensors for arbitrary non-uniform EulerBernoulli beam with rectangular cross-section are obtained. Finally, several numerical examples are given to demonstrate the feasibility of the proposed modal sensors with various boundary conditions. © 2012 Elsevier Ltd. Source

Zheng Y.G.,Nanchang Hangkong University
International Journal of Bifurcation and Chaos

The dynamical transitions resulting from time delay in single Hindmarsh-Rose system are investigated in the present paper. As the time delay varies, the change of the structure of slow manifold is first formulated by using the method of stability switch. Then, the delay-induced dynamical transitions are investigated through the analysis of geometric singular perturbation, and in several case studies, the mechanism of the dynamical transitions is illuminated. Numerical results demonstrate the validity of the theoretical results. © World Scientific Publishing Company. Source

Zheng Y.G.,Nanchang Hangkong University
Chaos (Woodbury, N.Y.)

The time-delay effect on the bursting of the synchronized state of coupled Hindmarsh-Rose neurons is investigated in this paper. The time-delay influence on the structure of the slow manifold is first studied by using the method of stability switch. And then on the basis of the geometric singular perturbation theory, case studies are given to show that the time delay can suppress the bursting oscillation or lead to more complex dynamics. In particular, the mechanism of the transition from bursting oscillation to relaxation oscillation and to chaotic bursting is stated. Numerical results are given to demonstrate the validity of the analytical results. Source

Wang L.,Nanchang Hangkong University | Liu X.,Dalian University of Technology
Information Sciences

This paper is concerned with the problem of computing the bounds of disturbances for continuous-time Takagi-Sugeno fuzzy model. Two kinds of disturbances are investigated by applying the non-parallel distributed compensation (non-PDC) law, non-quadratic Lyapunov function and Lagrange multiplier method. One is bounded by magnitude, the other is bounded by energy. If the exogenous disturbances are bounded by magnitude, the maximal value of the magnitude under which the closed-loop system can be controlled is obtained by solving an optimization problem. On the other hand, if the disturbances are bounded by energy, except for the maximal bound, some conditions are derived to get two local regions (a smaller and a bigger) such that all the trajectories starting from the smaller region will remain in the bigger one which is required to be contained in a specific compact set (where the original system can be represented as T-S model exactly). In the end, the effectiveness of the proposed results is demonstrated by two examples. © 2013 Elsevier Inc. All rights reserved. Source

Zhang L.,Nanchang Hangkong University
Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science

Pulsed magnetic field (PMF) processing has been employed for refining the microstructure of eutectic (Al-12.4Si) Al-Si alloy in the current study. The effect of PMF on microstructure and mechanical properties of eutectic Al-Si alloy was studied. The results show that the morphology of primary α-Al was refined from coarse columnar dendrites to fine equiaxed dendrites by PMF treatment. Fine short rod-like or rounded particle-like eutectic silicon was formed during solidification of eutectic Al-Si alloy treated by PMF. PMF treatment reduced the size of eutectic silicon from 49 to 2.3 μm in length, and the width from 3.1 to 0.6 μm. The aspect ratio of eutectic silicon was also reduced by PMF treatment from slightly less than 16 to slightly less than 4. The ultimate tensile strength and elongation of eutectic Al-Si alloy with PMF treatment at room temperature were about 201 MPa and 8.8 pct, respectively, which were increased by 47 and 73 pct, respectively, compared with the eutectic Al-Si alloy without PMF treatment. © 2012 The Minerals, Metals & Materials Society and ASM International. Source

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