Zhong Wanxie , Wu Zhigang , Gao Qiang
2004, 2(1):1-7.
Abstract:Based on the analogy between structural mechanics and Kalman filtering,a new extended Kalman-Bucy filtering algorithm was presented to identify parameters of continuous time systems.The algorithm employed the substructures assembly technique of structural mechanics,and the estimation of system states and parameters was embedded in the procedure of substructures assembling.The precise integration method provided all the off-line data for the parameter identification in advance.
Sun Yan , Zheng Changliang , Chen Jiefu , Zhong Wanxie
2004, 2(1):8-12.
Abstract:The fundamental equations of electromagnetic field were written in the form of duality system,and the variational principle for dual variables was derived for electromagnetic finite element method.To maintain the symplectic conservation conditions of FEM formulation,the integrand was rewritten dymmetrically for duality variables,and the boundary integral terms of variational principle were cancelled mutually for the adjacent elements.The dual variable FEM formulation can avoid the difficulty of C1 continuity condition.The FEM analysis for dual variables was applied to selve the eigenproblems of resonant cavity,and the generalized eigenvalues were solved numerically.In order to eliminate the spurious solutions owing to the violation of zero-divergence requirement in each element,the singular value decomposition (SVD) technique was employed,and the numerical results demonstrated the effectiveness of the method.
2004, 2(1):13-20.
Abstract:By expanding the power series solution of differential equations and using the semiqroups theory of Linear Operators,we studied the integration method of nonlinear dynamic equations and obtained the so-called Lie series method,whose concrete implementation was discussed.The Lie series method can be used to construct high order explicit integrators,so it was used to solve the generalized Hamilton system and it can preserve the canonical property of the exact solution of the generalizd Hamilton system.Numerical examples show the method's validity and effectiveness.
2004, 2(1):21-27.
Abstract:Based on the classical Magnus series method,This paper proposed a simple and efficient fourthorder integrator for solving the general nonlinear dynamic systems.The method is a kind of geometric integration method and can preserve many main qualitative porperties of the exact solution.The method involves only two or three matrix exponentials and thus avoids a lot of complex commutators involved in the Magnus method.The numerical examples were given to demonstrate the validity and effectiveness of the proposed method.
2004, 2(1):28-31.
Abstract:The Noether symmetry,the Lie symmetry and the form invariance for holonomic systems were presented.The Noether conserved quantity,the Hojman conserved quantity and a new conserved quantity deduced by the above three kinds of symmetries were studied.
Jin Bo , Zhao Yueyu , Zhou Haibing
2004, 2(1):32-36.
Abstract:The Hamilton principle of intrinsical linear nonholonomic system was studied.The sufficient and necessary conditions of stationary for Hamilton variational function are given and proved by using Appell-Chetaev condition or not.The results show that the Hamilton's action variable is a stable one in instrinsical linear nonholonomic system and the Hamilton principle is similar to that of holonomic system.There are no mechanical or mathematical contradications in the equations of motion gotten from the Hamilton principle.Finally,the essential reasons are given why it is unconscionable for the Hamilton principle to be generalized to the intrinsical nonlinear nonholonomic system.
2004, 2(1):37-39.
Abstract:According to the generalized Routh's equations in Poincare-Chetaev variables proposed by Rumyantsev,the symmetries and the conserved quantities of the equations were studied by using the method of infinitesimal transformation.The exixtence condition and the form of the conserved quantities were obtained.This result is more general than the past corresponding conclusions for Poincare-Chetaev equations.Two examples were given to illustrate the application of the results.
Chen Shuhui , Huang Jianliang , She Jinyan
2004, 2(1):40-45.
Abstract:The laterally nonlinear vibration of axially moving beams weve analyzed by the incremental harmonic balance(IHB) method.Firstly the motion equations of an axially moving beam weve derived by Hamilton's principle,Then the Galerkin method was used to discretize the governing equations.Finally, the IHB method was employed to solve the nonlinear vibration equations.Particular attention was paid to the fundamental,subharmonic resonance with internal resonance under the condition ω20/ω10≈3 as ω is near ω20,ω10,where ω is the forcing frequency,and ω10 and ω20 are the first and the second natural frequencies.The number results show that the IHB method is a very effective semi-analytical and seminumerical method for nonlinear vibration of axially moving system.
2004, 2(1):46-50.
Abstract:Based on a certain hypothesis,the strongly nonlinear system was transformed into a weakly nonlinear system by introducing a parameter transformation.Its solutions were expanded into the improved Fourier series,and the resonance cycle solutions were conveniently obtained by the undetermined parameter method.Using the method,we studied the principal resonance cycle solutions of the Duffing equation,the 3 ultraharmonic resonance cycle solutions of the Van der Pol-Mathieu equation.The examples showed that the approximate solutions closely coincided with numerical solutions.
2004, 2(1):51-58.
Abstract:The discrete singular convolution (DSC) was introduced for analyzing the dynamical responses of materially nonlinear pole.The discrete singular convolution (DSC) is a new numerical method,which has not only the high accuracy of global methods but also the flexibility of local methods.The discrete singular convolution (DSC)algorithm was adopted to discretize the spatial derivatives,while the fourthorder Runge-Kutta method was adopted to discretize the temporal derivatives.The DSC results were very consistent with the solutions obtained by the perturbation method.It indicates that the discrete singular convolution is a very efficient,robust numerical method with high accuracy for solving the responses of materially nonlinear structures.
2004, 2(1):59-64.
Abstract:This paper studied the Launch and control dynamics of Long Range Multiple Launch Rocket System (LRMLRS).We established a launch dynamics model and derived the launch and control dynamics equations for LRMLRS,which is a coupling multibody system including both rigid bodies and elastic bodies.By using the transfer matrix method of multibody system.We computed is vibration characteristics,we also presented the augmented eigenvector and its orthogonality conditions for LRMLRS.The dynamic response of LRMLRS was simulated,and the simulation results agreed well with the experimented datas.This study provided some basis to improve dispersion of fire and decrease rockets consumption in testing a LRMLRS.
Jin Wuyin , Xu Jianxue , Wu Ying
2004, 2(1):65-69.
Abstract:This paper examined effects of applying the weak periodic and chaotic perturbation to the ionchannels of Hodgkin-Huxley neuron.Numerical results indicate that the weak perturbation to differen ionchannel results in totally different behavior of neuronals spike.And the weak periodic perturbation can also control the neuronal spike from period to parabolic bursting,form chaos to period.
Gao Hangshan , Zhao Yapu , Lu Shengli , Deng Zichen
2004, 2(1):70-74.
Abstract:It is very important to develop numerical simulation methods in the research and design of micro-electro-mechanical systems.This paper reviewed the present numerical methods for the multiple energy-domain coupling simulation in MEMS.The status quo and the future research trends of this field were discussed.
2004, 2(1):75-81.
Abstract:According to the robust control theorry and the robotic dynamic characteristics,a robust controller was designed to overcome the uncertainties in the robot system by using the upper boundany of the uncertainties.The controller was applied to the robotic tracking control system,and its simulation results were compared with those of the PID controller.The simulation and comparision showed that the robust controller had better dynamic performance and stronger robustness than the PID controller.
2004, 2(1):82-86.
Abstract:Hysteresis is a phenomenon common to a broad spectrum of physical systems.However,due to its non-linearity and non-analysis,the parameter identification of hysteretic nonlinear system is very difficult,which damages it's offectireness in engineering.This paper proposed a new parameter identification method based on miche genetic algorithm,which employed a new parameter named Radius,and a wood shear wall described by the BW model was simulated using this method.The simulation results were compared with the real values,and it showed a great promise of the present algorithm in engineering.
Chen Zili , Tang Xiaodi , Peng Lihua
2004, 2(1):87-91.
Abstract:The expression for the relation between the deform and the external force of progressive rate springs with variable arm length was established by using unit load method,and then the non-linear dynamic equations was given.After solving the equations by means of multiple scales method,the modulation equations and its approximate solution were obtained.The curves of load and load point,frequency and the frequency response curves were given by illustrative examples.
Yang Duansheng , Huang Yan , Pan Jun
2004, 2(1):92-96.
Abstract:We established the differential equation for the free vibration displacement function of orthotropic rectangular thin plates on bi-pavameter elastic foundation.The equation can be used to accurately zolue the free vibration of plates with arbitrary boundaries.A square plate with four fixed edges was taken as an example to verify the method,and it showed that the calculation proless is simple and convenient.The method can also be suitable for single parametric elastic foundation and isotropic plates.