Applied Mechanics and Materials Vols. 215-216

Abstract: To achieve the assembly process control of aerospace complex precision mechanical systems and ensure its dynamic characteristics, parallel control theory and methodology is used in the assembly process. The main point is: assembly parallel control system is built corresponding to the actual assembly ones. The ultimate quality of assembly is guaranteed via alignment influence analysis on the dynamics characteristics of the assembly joint structural and the assembly machine and the dynamic characteristics-oriented alignment process optimization and decision-making to carry out computing operator and process decision-making in the assembly process. The dissertation ,regarding space sophisticated mechanical system assembly and its dynamic characteristics as study object, introduced the parallel control thought, presented the overall framework of assembly parallel control, built the assembly parallel control system(APCS) and given the main process and implement of assembly parallel control.

Abstract: Introduces the analog phase compensation technology used in electronic instrument transformer, put forward a method of digital phase compensation in electronic transformer and carries out in the 220KV electronic instrument transformer measurement system, the resolution ratio of the phase compensation is 1 second and the maximum range of the phase compensation is 270 second, which can meet the phase adjustment of electronic instrument transformer; compares the analog compensation technology and digital phase compensation technology, analyzes their characteristics and different applications.

Abstract: In this study, a robust H₂ suboptimal control method is proposed for an electro-hydraulic system with variable supply pressure. The H₂ suboptimal controller is designed to minimize the sum of a quadratic performance criterion and the H₂ norm of the closed-loop transfer function from the white noise disturbance to the system state space variables. The genetic algorithm is used to select the weighting matrices of the quadratic performance criterion. In order to improve the robust performance, parameter uncertainties of the electro-hydraulic system are considered in the process of genetic search. Simulation results demonstrate the effectiveness of the proposed approach.

Abstract: Slopes are a typical terrain of the rugged lunar surface. Using a modified model for wheel-terrain interaction, a terramechanics model for down-slope travel of a lunar rover is established. In order to describe the soil sinkage of different wheels more accurately, soil deformation by the front wheels is taken into account and the front and rear wheel sinkages are calculated separately. Finally, a motion control strategy for rover descent is proposed based upon analysis of its descending course, and validated by simulation in a 3D lunar rover visual simulation platform.

Abstract: Through two methods, wind speed data sets sequence, the elements of which increased in Mean Wind Speed (MWS) orderly, are introduced first, and a numerical integration method depending on Weibull fitting result and power curve data to calculate Power Generation (PG) is proposed in this paper. Then, with measured data of 3 wind farms, PG with different heights are calculated and contrastive studies are made, employing the proposed data sets processing and PG calculating methods. Research results indicate that the PG calculating method has high reliability, and Equivalent Available Duration (EAD) increases about 50-60h when MWS increased by 0.1m/s. The results provide important basis for studies on the relationship of PG variation and measured data correction methods.

Abstract: Simulation and analysis of the converter transformer valve side’s transient electric field by finite element method is proposed. The electric field of converter transformer valve side’s is calculated under polarity reversal condition, the maximum value of the electric field intensity of insulating materials and the potential distribution of the before and after first polarity reversal are given, obtaining the electric field distribution characteristics of the oil-paper insulation material in the case of isotropic and anisotropic before and after the first polarity reversal, and made a comparison. The numerical calculation result of the converter transformer valve side’s electric field is also given, and the comparison of the calculation results in the case of isotropic and anisotropic, for before and after the first polarity reversal is analyzed, obtaining the variation rule of the converter transformer valve side’s electric field and the variable factors which affected the distribution of the electric field.

Abstract: To take full advantage of and learn from overall structure of existing engine case, this paper presents parameterized, object-oriented method and similarity retrieval algorithms. A case library of parameterized engine overall structure is established by “top-down” master modeling method. On this basis, the management of engine parameters in case library is achieved, which built a foundation for the rapid design of new program at stage of overall structure design.

Abstract: The motivation for this development is to establish a new method of powertrain structural analysis and parameters matching of extended-range electric vehicle. For the main drawback of pure electric vehicle, which driving distance is short, the new powertrain will achieve efficient operation of range extender and extend the driving range effectually. The innovative technique is based on a co-simulation platform of AVL-Cruise and Simulink. A thermostat energy management strategy is adopted to verify the parameters of powertrain. Finally, the simulation results demonstrate that the system design and parameters matching of the whole vehicle powertrain are reasonable.

Abstract: A small vertical axis wind turbine with wind speed self-adapting was designed. The diameter and height of the turbine were both 0.7m. It featured that the blades were composed of movable and fixed blades, and the opening and closing of the movable blades realized the wind speed self-adapting. Aerodynamic performance of this new kind turbine was tested in a simple wind tunnel. Then the self-starting and power coefficient of the turbine were studied. The turbine with load could reliably self-start and operate stably even when the wind velocity was only 3.6 m/s. When the wind velocity was 8 m/s and the load torque was 0.1Nm, the movable blades no longer opened and the wind turbine realized the conversion from drag mode to lift mode. With the increase of wind speed, the maximum power coefficient of the turbine also improves gradually. Under 8 m/s wind speed, the maximum power coefficient of the turbine reaches to 12.26%. The experimental results showed that the new turbine not only improved the self-starting ability of the lift-style turbine, but also had a higher power coefficient in low tip speed ratio.

Abstract: A well-performed switched reluctance motor drive system was designed, and the diagram of the hardware on the basis of control system by TMS320F28335 chip was given. A fuzzy PI control method is developed to control SRM in drive system. On the platform of MATLAB/Simulink, the SRM drive system was researched and simulated. The stability of system is analyzed. The results indicated that the performance of SRM speed control system by fuzzy PI control algorithm is obviously better than that by conventional PI control algorithm.