Papers by Keyword: Precise Integration

Abstract: This paper considered the optimal placement of collocated piezoelectric actuator-sensor pairs on a thin cantilever plate using a modal-based linear quadratic independent modal space controller. LQR performance was taken as objective for finding the optimal location of sensor–actuator pairs.The discrete optimal sensor and actuator location problem was formulated in the framework of a zero–one optimization problem,which was solved by real-coded adaptive genetic algorithm (AGA). The vibration response of the piezoelectric plate was calculated using the finite element method (FEM).The optimization and vibration control programs were written by FORTRAN language. The results of numrical examples show that the adaptive genetic algorithm based on the minimum of LQR performance for the optimal location of sensors and actuators is feasible and effective.

Abstract: Based on time precise integration method, an improved precise integration method, which called, is studied in the paper to solve the dynamic equation of , where v is an unknown n dimensions vector, Hv and f are respectively the linear homogeneous part and nonlinear part on the right end of equation. Then the calculation expressions of the method are given. The numerical example of nonlinear dynamic analysis of low pressure rotor of high parameter turbine shows that the proposed method is no need to solve the H ^-1 and the computational accuracy and efficiency can be ensured.

Abstract: Due to the continuous increasing of operating frequency in the power system and the transmission speed, under the high frequencies of the transmission line calculation and simulation process, it is necessary to consider the frequency-dependent properties. At present, the frequency-dependent transmission line modeling has a variety of methods, but in the modeling and calculation of frequency variable term, processing is relatively complicated. This article will introduce transmission line equation of fractional calculus, intuitive representation of frequency varying parameters, and by a time-domain fractional solution, simplify the operation, improve the computational efficiency. Application of this algorithm for fractional differential equations can be obtained the voltage and current responses at any point in the transmission line. Thesis also by comparison with actual example, confirmed the validity and feasibility of the algorithm. At the same time, proposed algorithm can be extended to the multiple conductor transmission lines of fractional order model, also has certain applicability.

Abstract: Time-varying linear quadratic Gaussian (LQG) control for vibration of coupled vehicle-bridge system is studied. The vehicle is modeled as a moving mass model with three degrees of freedom, which consists of vehicle body, bogie and wheel. Active suspensions are adopted for the primary and secondary ones, and the control forces are produced by two actuators placed between the bogie and wheel, and between the vehicle body and the bogie, respectively. Vehicle-bridge coupling systems are time-dependent, which lead to the time-varying Riccati differential equation and the time-varying Kalman-Bucy filter equation in the LQG controller design. However, both of them are solved precisely via precise integration method and symplectic conservative perturbation method. In the example, the time history responses of the bridge and the vehicle were calculated respectively for the vehicle with passive suspensions or with active suspensions. Numerical results show that with active suspensions adopted, ride comfort can be improved when the vehicles passing through the bridge.

Abstract: Based on the principle of precise integration method, for DOF and MDOF system, it is supposed that external loads are in linear regular within small discrete time. In further, a identification method of dynamic loads are proposed. And two real ice loads are used to study the new method. The results of numerical examples indicate that the precise integration method, with better steady and capability of resisting noise, are applicable for both steady or random loads. Otherwise, it can save more time for calculation and can be applied in real engineering.

Abstract: In this paper, precise integration in a symplectic system is used to analyze the stop-band characteristic of the dielectric layer PBG structure in a waveguide. The transverse section is made discrete by using edge elements. The stiff matrices of a dielectric layer and an air layer can be calculated by precision integration based on Riccati equations in a Hamiltonian system. The export stiff matrices of a period can be obtained by a combination of substructures, and then the whole structure can be solved. The stop-band characteristic of a dielectric layer PBG structure in a waveguide is obtained and the effects of the size of period and the number of periods are discussed. The examples presented show that this method is precise and efficient.

Abstract: A precise integration algorithm for solving the restricted three body problem was put forward based on precise integration method, which divided a large integration time into small intervals and only small value matrix participates in the iterative process during the computation of the exponent matrix. And another symplectic algorithm for solving non-separable Hamiltonian system constructed by flow complex was also introduced, which only had periodic variational energy. The results of both algorithms were compared with fourth Runge-Kutta algorithm and their performances and advantages were analyzed, showing the validities of these two algorithms.