Applied Mechanics and Materials Vols. 644-650

Abstract: In order to research the random initial imperfections on the influence of steel braced frame structures deformation,the full-path advanced analysis by using the finite element software ANSYS for 20-story steel frame structures with the symmetrical arrangement of brace.The random initial imperfections in structural system and its individual members could be taken into account by Monte Carlo method,the lateral displacement of columns and the mid-span deflection of beams are gained according to probability statistics,and analysis method of various standards were compared.Results indicate that the ultimate deformation of steel braced frames are proportional to the size of the initial imperfections;The braced frame deformation considering random initial imperfections are closed to the results of ideal frames without imperfection.The ultimate bearing capacity calculated by advanced analysis of high-rise steel braced frame structures often does not meet the requirements of serviceability limit ,structural design ultimately controlled by the displacement limit.

Abstract: As a part of power transfer process, cylinder plays an important role in pneumatic system. Its failure can cause mechanical equipment downtime suddenly and gas leak, so that production and personnel security will be in danger. Cylinder lifetime prediction has been an important topic. In this paper, an adaptive method based on Kernel Density Estimation is put forward for predicting the cylinder lifetime and getting the reliability function of cylinders. Kernel Density Estimation is a nonparametric estimation method of statistics. It can make full use of samples data without assuming distribution model. In the end, a comparison is made on the cylinder experiment between the proposed method and the common used parameter estimation method, Weibull distribution, and the results show that the proposed method has a more satisfactory performance.

Abstract: This paper proposes a space vector motor control system based on DSP four-legged bridge topology A three-dimensional space vector control principle based on four-bridge arm three-phase inverter is introduced with a MATLAB model using space vector Motor Control Algorithm instead of traditional Motor Control method. A DSP experimental setup is also carried out to verify the control theory and simulation result. The experiment and simulation results show that the speed control system helps the asynchronous motor to achieve the consistent response characteristics with separately excited DC machine. When the motor doesn't work or the load is unstable, asynchronous motor can still achieve excellent electrical characteristics with the proposed speed control system, such as quick start, small overshoot and static torque ripple.

Abstract: Due to the test requirements of flyweel of the shaft-seal nuclear coolant pump, design the structure of the test bench.Based on the theory of finite element analysis,use ANSYS software carries on its ststic analysis to gain the displacement and the stress form in order to check the strength and stiffness,and then carries on modal analysis to get its first six natural frequency and vibration in order to verify the rationality of design.CLC :TH122

Abstract: This article analyzes, discusses the status of domestic water treatment and water treatment intelligent control systems, intelligent control of the water treatment system is deeply integrated, systematic research, the system successfully for a city sewage treatment.

Abstract: This paper analyses the structure of the original spinning multistage centrifugal fan. Because of low pressure and low efficiency, optimization design was carried out for the original fan. Based on the aerodynamic calculations theory, the structure and pneumatic of single stage was studied. The influence factors are Inlet-flow loss, equivalent divergent angle, pre-swirl, Resonant frequency etc. Pneumatic recalculation and experiment are carried out for the multistage fan. Results show that after modification pressure of the multistage fan has increased raises 15.3 %.

Abstract: The high precision control problem of a pursuer spacecraft approaching a space target in proximity missions is investigated in this paper. By choosing proper sliding mode surfaces, a novel adaptive sliding mode controller is presented in presence of model uncertainties and unknown external disturbances. It is proved that the relative position and attitude errors of the closed-loop system asymptotically converge to zero. The validity of the proposed control strategy is demonstrated by numerical simulation results.

Abstract: A novel methodology to design a robust attitude control and momentum management controller for the space station is proposed. Firstly, the method of maximum rank decomposition is adopted to deal with parameter uncertainties independently. Secondly, based on the resulted model, an optimal controller, with closed-loop region pole constraints, is designed. Finally, simulation results are presented to demonstrate the control effects.

Abstract: In this paper, a Fault Tolerant Control (FTC) strategy for Linear Parameter Varying (LPV) systems is proposed. The main idea of this FTC method is to transform the actuator fault to varying parameter such that an active FTC controller can be designed with gain-scheduled H_∞ control approach. The resulting controller is a function of the fault-effect factor which reflects the actuator fault and can be estimated on-line. The effectiveness and performance of the proposed approach are illustrated by a two-link manipulator.

Abstract: The dynamic performance of spindle unit have a directly influence on the stability of spindle. The 3D model of spindle unit is build in Pro/E and then guided into ANSYS workbench for modal and harmonic response analysis. The inherent frequencies are carried out by modal analysis. And displacement-frequency curves of dynamic response of spindle unit at the front end, in the middle position, at the rear end are carried out respectively. The results of analysis provide reference for spindle design optimization, and also improve the accuracy and working life of spindle unit.