FEA OF RUBBER WITH NOVEL STRAIN ENERGY FUNCTIONS

This paper presents the results of finite element analysis of rubber structures based on novel strain energy functions stemming from the representation theorem of tensorial function. The stress tensor is represented by Taylor expansion, using the representation theorem of tensorial function of a single tensorial argument for all terms in each order of the expansion. The scalar-valued coefficient functions of the theorem are represented by the integrity bases of the strain tensor and material constants to be determined by experiment. The computer implementation of the new constitutive laws has been verified by comparing the FE results with analytical solutions. A complicated structure of rubber bearing was analyzed. The FE results show good correlation with experimental data.     

ROBUST H∞ DESIGN OF THE ATTITUDE CONTROL/MOMENTUM MANAGEMENT SYSTEM FOR A SPACE STATION

Through input-output decomposition of structured parameter uncertainties of the controlled plant, the robust control problem of space station attitude system with parameter uncertainties is converted to a conventional disturbance rejection H∞ controller design problem, then a full-state feedback H∞ robust controller is formulated, which can be solved using the Glover-Doyle algorithm. The proposed method was applied to the attitude control/momentum management (ACMM) system of a space station, and two kinds of parameter uncertainties which appear most frequently in spacecraft engineering were considered. Simulation results showed efficiency of the given method.     

提高动量实验仪测量精度的研究

动量实验仪是验证流体动量方程的重要仪器。国内外常用的动量实验仪测量精度较低，冲击力的测量值与理论计算值偏差Δ值在２２％ 以内。本文介绍了影响测量精度的几个关键性技术问题及其解决方法，研制出一种高精度小型动量仪，将Δ值降至５％ 以内。     

球铁汽车零部件球化率超声声速检测法研究

球铁汽车零件的球化率测试，过去都是由金相的方法得出。该方法测试工期长，人为因素较大。本文研究超声声速法来测球铁的球化率。实践证明，该方法可用于生产实际中。     

降低聚苯乙烯粉末激光烧结收缩率的研究

本文通过分析聚苯乙烯粉末激光烧结成型机理，探索其烧结收缩产生的原因并研究降低试样收缩率的方法。结果表明，添加无机填料可提高苯乙烯粉末激光烧结性能，而且，多种填料同时添加，效果更明显。     

弹载微小型化三轴一体光纤陀螺组合设计

为满足新一代导弹用三轴一体光纤陀螺组合高精度、集成化、高可靠等技术要求,通过采用光学及电子元器件系统级封装技术（System In a Package,SIP）实现陀螺敏感组件模块化设计,采用陀螺敏感组件热隔离设计等方法,在优化三轴一体光纤陀螺组合返修性和总体设计接口适配性的前提下,提高了产品角速度测量性能指标。产品实测零偏稳定性达到0.037o/h,冲击振动及温度环境适应性优异,并与导弹飞行控制系统集成实现光电探测、惯性导航及姿态控制等功能。     

High-order implicit discontinuous Galerkin schemes for unsteady compressible Navier–Stokes equations

Efficient solution techniques for high-order temporal and spatial discontinuous Galerkin(DG) discretizations of the unsteady Navier–Stokes equations are developed. A fourth-order implicit Runge–Kutta(IRK) scheme is applied for the time integration and a multigrid preconditioned GMRES solver is extended to solve the nonlinear system arising from each IRK stage. Several modifications to the implicit solver have been considered to achieve the efficiency enhancement and meantime to reduce the memory requirement. A variety of time-accurate viscous flow simulations are performed to assess the resulting high-order implicit DG methods. The designed order of accuracy for temporal discretization scheme is validate and the present implicit solver shows the superior performance by allowing quite large time step to be used in solving time-implicit systems. Numerical results are in good agreement with the published data and demonstrate the potential advantages of the high-order scheme in gaining both the high accuracy and the high efficiency.     

无位置传感器无刷直流电机控制技术在血泵中的应用

针对血泵要求电机控制系统硬件电路简单、速度控制精确、稳定可靠等特点,本文论述了基于可编程逻辑芯片XC3S400的无位置传感器无刷直流电机控制系统,介绍了无位置传感器电机控制的反电势过零测转子位置、速度闭环控制.软件结合了增量式PID算法的优点,实现精确稳定的速度闭环控制.经过溶血与动物试验结果表明,本控制系统调速性能好、稳定可靠,对血泵溶血、动物试验的长期运行起到了很好的保障,该控制系统已应用于实际的产品中.     

Formability enhancement in hot spinning of titanium alloy thin-walled tube via prediction and control of ductile fracture

The damage and fracture in hot spinning of titanium alloy is a very complex process under the combined effects of microstructure evolution and stress state. In this study, their dependences on processing parameters were investigated by an integrated FE model considering microstructure and damage evolution, and revealing the effects of microstructure and stress states on damage evolution. The results show that the inner surface of workpiece with the largest voids volume fraction is the place with...     

非圆实信号MIMO雷达中基于实值ESPRIT的角度估计

研究单基地多输入多输出(MIMO)雷达中的波达角(DOA)估计问题,提出了一种基于非圆(NC)实信号的实值旋转不变性信号参数估计(ESPRIT)算法.首先对接收信号进行降维变换,降低运算复杂度;之后根据非圆实信号特性构造中心Hermitian对称矩阵,通过酉(Unitary)变换将复数运算转为实数,进一步降低复杂度;最后根据ESPRIT得到角度估计.该算法无需谱峰搜索,运算复杂度较NC ESPRIT和Unitary ESPRIT大大降低,且该算法的角度估计性能优于后两种算法.论文分析了所提算法的复杂度,并推导了克拉美-罗界(CRB).仿真结果验证了该算法的有效性.