A Note on the Multivariate Process Capability Index MCpm

Important features of multivariate process capability indices are comparability, interpretability and ease of implementation. When poor process capability is indicated by an index, the user should determine why the process is incapable (e.g. excessive variability or off‐target process mean). One of the most used multivariate process capability indices is MC_pm because it provides assessments of process precision and accuracy. In this work, we study and discuss a peculiarity of MC_pm: processes that are equivalent in terms of precision, accuracy and MC_pm index, after the occurrence of the same increase in the process variability, can have different values of the index. Because MC_pm is often used for comparing processes, this behaviour may cause comparability difficulties. Therefore, we suggest how to take into account this specific behaviour for avoiding erroneous conclusions. Copyright © 2013 John Wiley & Sons, Ltd.     

磁力齿轮伺服系统的观测器状态反馈控制

针对磁力齿轮的低刚度特性,从具体的控制策略角度开展磁力齿轮在伺服驱动系统中应用的研究。建立了包含磁力齿轮伺服开环系统的物理以及数学模型,利用极点配置算法对系统闭环极点进行配置,重点引入观测器设计,主要内容包括观测器控制器的设计原理、算法、实例以及仿真分析,实现系统的闭环控制。仿真结果表明:该观测器可以很好的实现对一些难以直接获得的状态变量进行观测,从而使得相应的极点配置得以在实际系统中实现,并且系统获得了良好的动、静态响应。     

重频结构大修改动力重分析的矩阵摄动法

为拓展矩阵摄动法在结构重分析中的适用范围,提高重分析计算精度,针对重频结构参数大修改提出了重频结构动力重分析的矩阵摄动法。采用高次增量法将反映重频结构参数改变的质量矩阵和刚度矩阵的增量分别表示为小参数ε的一次与二次幂项之和,根据矩阵摄动理论推导得到重特征值的二阶摄动解及相应特征向量的一阶摄动解。数值算例表明,所提出方法极大提高了重频结构大修改下的动力重分析计算精度。     

Aggregation based on graph matching and inexact coarse grid solve for algebraic two grid

A graph matching is used to construct aggregation-based coarsening for an algebraic two-grid method. Effects of inexact coarse grid solve is analysed numerically for a highly discontinuous convection–diffusion coefficient matrix, and for problems from the Florida matrix market collection. The proposed strategy is found to be more robust compared to a classical algebraic multi-grid approach based on strength of connections. Basic properties of two-grid method are outlined.     

具有随机约束刚度的结构的特征值

建立了结构边界具有随机约束刚度的特征值问题的方程和边界条件,通过摄动法,将随机的微分方程和边界条件化为一组确定的微分方程和边界条件。利用有限元离散方法,得到了统计特征值的一阶摄动近似表达式,并用算例对方法进行了说明和验证。     

控制混沌及超混沌

提出的自适应校正方法既适用于控制混沌系统又适用于控制超混沌系统，不需关于体系动力学的知识也不需要任何人部的控制参数。作者先系统地推导出了反馈矩阵的具体形式，进而将该方法应用到混沌Henon系统和一个超混沌系统，模拟结果表明，受控的不稳定轨道都以指数速率趋于预定点。     

有向图能量的广义Coulson型积分公式

对于一个有向图D,它的能量E(D)定义为对应邻接矩阵的所有特征值实部的绝对值之和.本文利用复分析的方法给出了有向图能量的一个广义Coulson型积分公式,通过这个公式建立了有向图的能量与有向图的特征多项式之间的联系.     

A semi-inverse variational method for generating the bound state energy eigenvalues in a quantum system: the Dirac Coulomb type-equation

Exact eigenspectra and eigenfunctions of the Dirac quantum equation are established using the semi-inverse variational method. This method improves of a considerable manner the efficiency and accuracy of results compared with the other usual methods much argued in the literature. Some applications for different state configurations are proposed to concretize the method.     

Bipenalty method from a frequency domain perspective

In a recent paper, it was shown that for time domain analysis, the simultaneous use of inertial and stiffness type penalty parameters to enforce constraints was found to yield accurate and converging results without causing any stability problems. From a frequency domain perspective, this is somewhat unexpected because the solution converges from below when stiffness penalty parameters are used to model constraints, and the convergence is from above when inertial penalty parameters are used. The purpose of this paper is to explain the effect of the simultaneous use of stiffness and inertial penalty parameters on the natural frequencies of constrained systems. In this work, it is shown that if suitably tuned, the bipenalty approach works well for frequency domain analysis also, and that with two different tuned set of stiffness and inertial penalty parameters, bounded solutions to the natural frequencies of constrained systems may be obtained. The method is applicable for any linear eigenvalue problem. Copyright © 2012 John Wiley & Sons, Ltd.