A Theory of Reactor Diagnosis in Feedback Systems

A unified theory is presented for diagnosis of power reactors with feedback mechanism. In terms of correlation functions calculated from stationary time series data, a feedback system can be expressed by an equivalent innovation model. From the formalism the identifiability of open loop transfer functions in the feedback system is discussed under conditions; (1) the minimum phase system, (2) the independence of noise sources. From the feedback structure, the property of the nonminimum phase is related to that the reactivity is positive or zero-power reactor transfer function is supercritical. In the case of the nonminimum phase and correlated noise sources, there is a possibility of new additional loops in an innovation model equivalent to the feedback system.     

Effective Convergence of Fission Source Distribution in Monte Carlo Simulation

The effective technique to accelerate the convergence of a fission source distribution in a Monte Carlo simulation is proposed as an application of a fission matrix. It is found that this acceleration method is especially useful for large core analysis where the fission source distribution is slowly converged in a Monte Carlo simulation by the source iteration method. It is found that the number of inactive cycles can be automatically determined and reduced by the acceleration method in this investigation.     

水下电磁场源的二维DOA和极化估计

以电磁矢量传感器在均匀海水中的电声测量为运用背景,建立了水中单个电磁矢量传感器的数据接收模型,采用特征值分解的信号子空间TLS-ESPRIT算法,对基于该算法的单个电磁矢量传感器估计多个信号源的DOA和极化参数问题进行了研究。     

A note on stability of linear time‐variant electrical circuits having constant eigenvalues

The main aspect of this paper is to show that the stability of linear time‐variant systems cannot be estimated from the location of the eigenvalues. For this purpose, two simple time‐variant electrical circuits are presented, which have constant eigenvalues. As will be shown, the time‐variant circuits can be asymptotically stable although there is a positive eigenvalue and this circuit can be unstable despite negative eigenvalues only. The idea behind is a suited time‐variant state transformation of a linear time‐invariant system. An electrical interpretation of both systems and of state transformations allows for an energetic evaluation from an electrical point of view even though the analytical solution is not necessarily known. Copyright © 2012 John Wiley & Sons, Ltd.     

用时间序列来判断电力系统中的混沌现象

由于混沌现象对初值、参数等的敏感依赖性,现有的基于电力系统的模型（方程）来研究混沌的方法,会由于建模时方程的形式、参数等误差带来可能的失误。为了弥补这一缺点,文中提出了直接利用对实际系统RS采样得到的时间序列的Lyapunov指数λi分析的方法来判断混沌的存在性。利用矩阵的特征值移动技术可以找到RS的伴随系统RS*,使RS* 的λ*i=λi+k(k为合适的正实数),于是可以利用现有的计算时间序列Lyapunov指数的方法来实现RS的混沌判断。     

随机参数结构振动控制的特征值分析

以物理参数为随机变量的结构为研究对象,从随机结构刚度矩阵和质量矩阵中提取出随机因子并将其引入振动控制方程,用随机因子来表示控制方程中参数的随机性．并利用代数综合法推导出振动控制特征值的均值和方差的表达式．同时,应用3σ准则对随机结构振动控制的稳定性进行了分析,得出了稳定性的判据．通过一个悬臂梁的算例表明,弹性模量对振动控制闭环特征值的影响要大于质量密度的作用,表明了文中方法的可行性．     

不确定性结构特征值上下界的估计方法

用凸模型理论描述了结构参数的不确定性 ,提出了一种用于估计含不确定性参数结构特征值的上下界的新方法 ,并以框架结构特征值的算例验证了所提理论的有效性。     

进化策略算法在矩阵特征值求解中的应用

工程实践中多种振动问题的求解常常归纳为求矩阵特征值问题,另外一些稳定性分析问题及相关分析问题也可以转化为求矩阵特征值问题.为了有效求解此类问题,提出了一种新的求解矩阵特征值的进化策略算法,该算法可用于求解任意矩阵的特征值.实验结果表明,这种基于进化策略算法求解矩阵特征值的方法,与传统方法相比,表现出求解精度高,收敛速度快等优点.     

Augmented canonical forms and factorization of graphs

The main aim of this paper is to generalize the previously developed canonical forms by different types of alterations and/or augmentations. These forms provide suitable tools for the decomposition of the matrices of special patterns and lead to efficient aproaches for calculating their eigenvalues. Methods were developed for factorization of symmetric graphs into smaller subgraphs using decompostion and healings (Commun. Numer. Meth. Engng 2003; 19 :125–136, 2004; 20 :133–146, 2004; 20 :889–910; Comput. Struct. 2004; 18 :2229–2240). Further factorization was possible only when further symmetries were available. The main drawback was associated with non‐decomposiblity of some of the factors in early stages of decomposition, and in particular healing which often destroyed the symmetry. In this paper, the mathematical concepts related to certain symmetric and unsymmetric graphs are developed, making refined factorization of the graphs feasible. Examples are included to show the simplicity of the operations being involved. Copyright © 2005 John Wiley & Sons, Ltd.