Abstract:The extended Wittrick-Williams algorithm combined with the precise integration method is used to compute the propagation of non-stationary random waves in anisotropic materials.The responses of the surface due to the non-stationary random excitations of the bedrock are investigated.Based on the natural frequencies and modes computed by means of the pseudo excitation method and the precise integration method in combination with the extended W-W algorithm,the mode-superposition scheme are jointly used to solve the differential equation of non-stationary random wave propagation in layered anisotropic materials.The power spectral density of the surface random responses is thus obtained.

Abstract:By a piecewise linear unimodal map,we described the mathematical of Feigenbaum attractor and proved that the quadratic family possessed a nest of proper Fμ cycles with period 2n which determined an attractive minimal Cantor set.The subsystem of the map on the set was topologically conjugate to a so-called "adding machine" on the symbol sequence space.Some supplements were added to the recent results and several proofs were simplified.

Abstract:This paper addresses a few dynamic problems of carbon nanotubes through the illustrative examples of (5,5)and(10,10) armchair single-walled carbon nanotubes.It presents the results of molecular dynamics simulation for the normal impact of the carbon nanotubes with a rigid wall,and the simulation results of the propagation of harmonic longitudinal waves in the carbon nonatubes.It also demonstrates the validity of dynamic model of an elastic rod for those dynamic problems.The elastic rod model enables one to study the high-speed impact of microstructures in those carbon nanotubes when the wave dispersion in under study.

Abstract:The unqualitative and nonlinear problems of virtual displacement in nonholonomic system are studied. The concepts of intrinsical linear nonholonomic constraint and intrinsical nonlinear nonholonomic constraint are put forward. The spectrums in applying all kinds of the virtualdisplacement concepts and the commutativity operations were testified and given. The study shows that,in intrinsical linear nonholonomic system, all kinds of the virtualdisplacement concepts and the commutativity operations are rational; But in intrinsical nonlinear nonholonomic system, they are not rational. So the physical realization of intrinsical nonlinear nonholonomic constraint must be studied.

Abstract:The conservation law of mechanical energy in variable mass mechanical systems with ideal bilateral holonomic constraints is studied. First, by using the differential equations of the motion of the systems, the equation of energy variation is obtained, and the sufficient and necessary condition under which the conservation law of mechanical energy exists is given. Then, the 27 cases possessing the conservation law are presented.Ａt last, some examples are given to illustrate the application of the result.

Abstract:An undamped two-degree-of-freedom vibro-impact system with a harmonic excitation is studied based on the theoretical analysis by Poincare map.A criterion for the existence of single impact period-1/n motions is obtained,and the initial position of the subharmonic periodic motion can be determined.The stability and the bifurcation of periodic motions are studied by computing the characteristic values of the Jacobian matrix.A combination of analytical and numerical techniques is proposed in the study of periodic motions of vibro-impact systems.

Abstract:For analyzing the vibration characteristics of a kind of structure with clearances,and for discussing the rationality of prekeeping clearances in protecting the special substructure, we reduce the nonlinear structure with clearances to 1DOF system with clearances and 2DOF system with clearances,by adopting the mass and the firstorder bending stiffness of its substructures on the basis of Assumption Modal Method and its vibration results. We analyze the effect of the clearness on the response of the system under different exciting conditions. The results indicate that the clearances can hold back the transfer of the vibration and it is rational to prekeep the clearances in the system.

Abstract:In order to modify the steadystate resonance responses, a nonlinear parametric feedback control was proposed to reduce the amplitude of the response and to eliminate the saddlenode bifurcations that take place in the resonance responses.From the singularity theory approach, the nonlinear gain of the feedback control was determined by analyzing the bifurcation diagrams associated with the corresponding frequencyresponse equation.The illustrative examples show that the proposed nonlinear feedback is effective for controlling the primary resonance response.

Abstract:A new method of active structral control which combines LQG controllers with independent modal space control is presented.The model reduction is first carried out by balanced reduction method,then LQG control strategy is used in modal space for control design.An effective analysis approach is given in terms of complex modal superposition method and pseudo-excitation method.The method is validated by an example of active control of seismic responses of offshore platform.

Abstract:By using the method of switched system in hybrid control,4WS optimal controllers for highspeedstate subsystem,lowspeedstate subsystem and the switched system which transforms from high speed state to low speed state were designed respectively for the first time.Computer simulation showed that the flexibility at low speed and the stability at high speed were carried out by hybrid control,and that the controller had a satisfactory control effect.

Abstract:The problem for the multi-rigid-body contact/impact system can be generalized,into a mathematical model,which combines an ordinary differential equation in time with an instantaneous complementarity condition.This paper developed a variable implicit time-stepping scheme for the simulation of the multi-rigid-body contact/impact system with frictionless based on the linear complementarity formulations.A numerical example was provided and the effectiveness of the algorithm for the numerical simulation of such problems was demonstrated.

Abstract:The large angle attitude maneuvers control by using reaction wheels for gravity gradient stabilized small satellites is stutied ．By introducting quaternion to describe the satellite attitude,a sliding mode is selected and the control law is developed.The histories of the satellite attitude and the angular rates of the reaction wheels during the process of the large angle attitude maneuver are obtained.Both theoretical analysis and simulation show that the variable structure control law is asymptotically stable and robust.

Abstract:This paper proposed a control method for the vibration of the hard-sandwich plate made of shape memory alloys(SMA) and ordinary steel,obtained an equilibrium equation for the hard-sandwich plate,and analyzed the vibration of the smart changed hard-sandwich plate.An numerical example shows that the method is feasible.

Abstract:Based on the effects of temperature upon the material properties of cylindrical shells,this paper established a geometrical nonlinear dynamic control equation of cylindrical shells under disturbing external pressure,and studied the bifurcation of cylindrical shells under thermal load and disturbing external pressure by using Galerkin's principle and Melnikov's method. It also discussed the effects of temperature, Batdorf's parameter etc. upon the chaotic motion region of cylindrical shells. The results show that the chaotic motion region enlarges when the temperature or the Batdorf's parameter increases.

Abstract:First,the knowledge of mechanics and electromagnetics was applied to build the equilibrium equation of thick-walled cylinders' structures,and a solvable equation was obtained utilizing the Laplace transforms and the Hankel integral transforms.Then, we presented an analytical method to solve the dynamic stresses and perturbation of magnetic field vector under thermomagnetic shock,and obtained the response histories and distributions of the dynamic stresses and the response histories of perturbation of magnetic field vector.Finally,some practical examples were used to test the method,and it proved that the method was simple and effective.

Abstract:A multiinput multioutput direct adaptive fuzzy generalized predictive control method for a micromanipulator with flexible joints is presented. First, a generalized predictive controller is designed based on the manipulators theoretical model. Then, in order to increase the robustness for modeling errors, a direct adaptive fuzzy controller is constructed to approximate the generalized predictive controller，and the fuzzy controller parameters as well as the unknown vectors in the generalized error estimation vector are adjusted adaptively by the use of vision error information. It is proved that，when the micromanipulator tracks a time－varying reference trajectory, the proposed controller forces the norm of the generalized error estimation vector to converge to a small neighborhood of the origin，thus the control requirements can be fulfilled. Simulation results demonstrate the effectiveness of this method.

Abstract:This paper proposed two control methods for the vibration of rotor system-gray GM(1,1) forecasting-optimal control method and gray Verhuslt forecasting-optimal control method.Based on the gray forecasting theory,using the optimization control method of the modern control theories,and modeling by gray GM(1,1) and gray Verhuslt model,a gray forecasting-optimal control scheme was designed for a symmetric rotor bearing system,which has a single round plate.The simulation result shows that the two methods are efficient for the vibration control of rotor system.