砼泵车臂架回转支承的力矩验证分析

通过理论与实践相结合的方法，对砼泵车臂架析拟定06.1390.03型交叉滚子式带外齿的回转支承进行力矩分析、验证。结果证明：各力矩符合回转支承的各项参数要求。这种计算过程对于其他大型工程机械等方面的回转支承验证分析有一定的指导意义。     

频率选择表面电磁仿真

文中采用谱域法对频率选择表面(Frequency Selective Surfaces)进行仿真,谱域法是与矩量法结合在一起的.谱域法与国内常用的模式匹配法相比能仿真具有更复杂形状的FSS单元,且在计算多个介质夹层中的FSS计算量小,并能得出非常理想的仿真结果并用于设计.本文采用这种方法得到的结果与实测结果相吻合.     

强散射体的RCS分析

用简单的强散射体制作简易的目标模拟体．以较小的反射体模拟散射较强、体积较大的目标可以有效地提高目标的生存能力,达到伪装、迷惑的目的．常见的强散射体有二面角反射体、三面角反射体等,采用矩量法计算它们的RCS,通过分析、比较和计算结果来选择合适的强散射体．     

基于罗朗级数的矩量匹配技术及其在去耦电容选择中的应用

提出一种新型的矩量匹配技术,不同于传统的基于泰勒级数的矩量匹配,该技术基于罗朗级数展开,考虑了负幂项的作用;通过灵活选择展开阶次,可以在指定区域内或外,非常有效地逼近所给函数.本文针对电源分配系统的去耦电容选择问题,将该型矩量匹配技术应用于这一领域.结果表明,利用该方法可以快速选择合适的电容大小,降低系统的端口阻抗,进而达到优化设计的目的.     

Moment quantization of inhomogeneous spin ensembles

Robust excitation of a large spin ensemble is a long-standing problem in the field of quantum information science and engineering and presents a grand challenge in quantum control. A formal theoretical treatment of this task is to formulate it as an ensemble control problem defined on an infinite-dimensional space. In this paper, we present a distinct perspective to understand and control quantum ensemble systems. Instead of directly analyzing spin ensemble systems defined on a Hilbert space, we transform them to a space where the systems have reduced dimensions with distinctive network structures through the introduction of moment representations. In particular, we illustrate the idea of moment quantization for a spin ensemble and illuminate how this technique leads to a dynamically equivalent control system of moments. This equivalence enables the control of spin ensembles through the control of their moment systems, which in turn creates a new control analysis and design paradigm for quantum ensemble systems based on the use of truncated moment systems.     

Delay-independent stability of moments of a linear oscillator with delayed state feedback and parametric white noise

The stability of a linear oscillator with delayed state feedback driven by parametric Gaussian white noise is studied in this paper. The first and second order moment equations of the system response are derived by using moment method and Itô differential rule. Based on the moment equations, the delay-independent stable conditions of both moments are proposed: For the first order moment, the sufficient and necessary condition that guarantee delay-independent stability is identified to that of the deterministic system; for the second order moment, the sufficient condition that ensure delay-independent stability depends on noise intensity. The theoretical results are also illustrated with numerical simulations.     

用连杆组合的拟人双足步行机的设计与动态步行控制

本文应用一种简捷的连杆组合建立了拟人两足步行机的结构模型，着重研究了它的动态步行稳定性，深入讨论了直线步行规划和对踝关节的力矩控制及其实现方法。实施这一规划，完全避免了步行机侧向倾倒的可能性。由于具有反馈的力矩控制，在无需复杂的硬、软件条件下，达到了对踝关节的控制要求，并获得较高稳态的仿真效果。为适应作业领域的总体要求，给出了步行机全方位性表达及其判据。这对于研究步行机实现高级步态及其对坡地、阶梯地的适应性研究奠定了初步基础。     

A copula-based Gaussian mixture closure method for stochastic response of nonlinear dynamic systems

Gaussian closure method is commonly used in the analysis of nonlinear stochastic systems. However, Gaussian closure may lead to unacceptable errors when system response is very much different from being Gaussian, and accuracy of the method decreases as the nonlinearity of the system increases. The need for better accuracy in strongly non-linear problems has caused the development of non-Gaussian closure schemes. In this paper, we develop a new copula-based Gaussian mixture closure method for randomly excited nonlinear systems. Our method relies on the assumption of marginal PDF of response in terms of finite Gaussian mixture model, and the derivation of joint PDF with aid of dependence modeling of Gaussian copula. By substituting the non-Gaussian PDF representation into moment equations of nonlinear system, we further develop an optimization-based closure scheme for the solution of the unknown parameters in joint PDF. In this way, PDF and thus, moments of response of highly nonlinear system can be described in a more flexible and robust way. Effectiveness of the new closure method is demonstrated by a nonlinear and a Duffing oscillator that are subjected to Gaussian white noise. The results are compared with the Gaussian closure and exact solution. It has been shown that Gaussian closure is a special case of the new closure method, and accuracy of Gaussian closure is the lower bound of that of the new closure method.     

谐和与高斯白噪声联合作用下二自由度系统的随机稳定性研究

主要研究了谐和与高斯白噪声共同作用下二自由度系统的随机稳定性问题.首先,通过扩维的方式将非自治系统转化为自治系统.其次,利用摄动法和双傅里叶级数展开的方法求得了系统的矩Lyapunov指数与最大Lyapunov指数的近似解析结果,并和利用Monte Carlo仿真得到的数值结果进行了比较验证.最后,通过对系统矩Lyapunov指数和最大Lyapunov指数解析结果的研究分析,分别讨论了次谐共振和组合共振对系统随机稳定性的影响.     

变惯量机载天线控制中转动惯量在线辨识器设计及仿真

机载天线稳定跟踪系统在复杂的动态环境中,为削弱天线载体在运动过程中转动惯量的变化对系统控制性能的影响,针对天线伺服系统设计出在线辨识转动惯量环节并前馈实现速度环自整定的控制策略。采用模型参考自适应辨识算法设计出系统平稳运行时的转动惯量辨识器,利用三阶最佳设计法将转动惯量辨识值前馈速度环进行自整定控制。在Simulink中自定义电机及辨识器模型,仿真观测出辨识器在不同自适应增益下的辨识精度,将其前馈至速度环进行自整定,仿真结果表明自整定速度环控制下系统速度响应的快速性和准确性。