Parameterized ABD preconditioning technique for time-periodic convection–diffusion problems

In this paper, a parameterized additive block diagonal (PABD) preconditioning technique is present for solving the nine-point approximations of the time-periodic convection–diffusion problems. The explicit expressions for the eigenvalues and eigenvectors of the corresponding preconditioned matrices are presented. The range of the optimal parameters is derived. Numerical experiments show that the generalized minimal residual method preconditioned by the PABD preconditioner with the experimental optimal parameters or some special values is effective for a wide range of problem sizes.     

基于磁弹法的磨削烧伤检测及定标在企业中的应用

描述磨削烧伤及相应检测手段，介绍一种新颖、高效、实用的“磁弹法”的工作原理，以及专用仪器，重点叙述应用磁弹法时的评定指标和仪器的特征值定标，通过实例予以说明。     

Generalized eigenvalue minimization for uncertain first-order plus time-delay processes

This paper shows how to apply generalized eigenvalue minimization to processes that can be described by a first-order plus time-delay model with uncertain gain, time constant and delay. An algorithm to transform the uncertain first-order plus time delay model into a state-space model with uncertainty polyhedron is firstly described. The accuracy of the transformation is studied using numerical examples. Then, the uncertainty polyhedron is rewritten as a linear-matrix-inequality constraint and generalized eigenvalue minimization is adopted to calculate a feedback control law. Case studies show that even if uncertainties associated with the first-order plus time delay model are significant, a stable feedback control law can be found. The proposed control is tested by comparing with a robust internal model control. It is also tested by applying it to the temperature control of air-handing units.     

A Guass–Newton-like method for inverse eigenvalue problems

In this paper, we propose a Guass–Newton-like method for finding least-square solutions to inverse eigenvalue problems. We show that the proposed method converges under some mild conditions. In particular, if the method converges to the exact solution, the convergence rate is at least quadratic in the root sense. Numerical examples are given to justify the theoretical result.     

塔河油田奥陶系碳酸盐岩储层预测新进展

经过多年的理论研究与生产实践相结合,在塔河油田奥陶系碳酸盐岩缝洞型储层预测方面取得了丰富的成果,形成了一系列的方法技术。近两年又创新推广了新技术趋势面法的应用,对一些前期成熟技术进行了发展与延伸,如本征值精细相干,并且加强了多方法的联合应用,取得了较好的效果。     

A Model-trajectory-based Method for Analyzing the Time-varying Oscillation Characteristics of a Fault System

Due to the impossibility for the equilibrium-point eigenvalue method to reflect the oscillation characteristic of the fault system correctly, and the difficulty in choosing the window length using a trajectory eigenvalue method, a model-trajectory method is proposed to analyze the eigenvalue of a fault system. First, the system is equated by the mutual factor after fault clearance. Then the branch current and power of the post-fault system is calculated by the branch current of the original and the fault component network, respectively. Furthermore, the equivalent model of the system is built and linearized at each measuring point. By combining the linearized model with the actual disturbed trajectory, the time series of the eigenvalue of the fault system is calculated. Simulation results of 2-generator system and a 16-generator system illustrate that the model-trajectory method is able to describe the time-varying oscillation characteristic of a fault system effectively and accurately.     

双馈风电机组附加控制对轴系振荡影响的评估方法

为消除绝对特征值灵敏度指标中参数量纲的影响,同时计及风速的概率分布特性对特征值灵敏度排序的影响,提出了一种累积相对特征值灵敏度(CRES)指标及其计算方法,并基于该指标定量评估了双馈风电机组附加控制(有功功率调制、虚拟惯性控制、下降控制、无功功率调制和机端电压控制)对机组本身轴系振荡阻尼的影响。CRES本质上是相对特征值灵敏度的加权和。通过引入相对特征值灵敏度消除了参数量纲的影响;在此基础上,按照转子运行状态将风速划分为若干区间,以平均风速作为该区间的典型风速,以风速落入该区间的概率作为该区间典型风速下计算所得相对特征值灵敏度的权重。时域仿真结果表明:基于CRES指标能有效地确定不同类型附加控制中影响轴系振荡阻尼的关键参数,通过对关键参数的重新整定可显著减小附加控制器对轴系振荡的不利影响和降低其对传动轴系统的转矩冲击。     

基于小干扰稳定约束可用传输容量的计算

小的干扰能够引发电力系统发生低频机电振荡,因此小干扰稳定是限制电力传输容量的主要因素之一.文中提出了一种基于小干扰稳定约束改进二阶连续潮流可用传输容量的计算方法,通过特征值的灵敏度指标重新调度发电出力,以改善电力系统的小干扰稳定性;针对发电机或传输线达到极限是一个非线性的现象,提出改进的二阶连续潮流可传输容量的算法,利用一阶指标中的附加信息来克服其线性不好的弱点,并通过控制变量的灵敏度计算减少了二阶连续潮流的搜索范围.新英格兰10机39节点系统的计算结果表明了用该方法计算ATC的有效性和可行性.     

应用信号变化度的线性混合信号盲分离算法

论文首先给出了信号变化度的概念,并证明了信号变化度的一个性质:互相独立的一组源信号的线性混合信号的变化度介于源信号中的最小变化度和最大变化度之间。然后,利用矩阵广义特征值理论,给出了一种基于线性混合信号盲分离算法。该算法计算简单,具有闭解形式;并能分离源信号中既有亚高斯信号又有超高斯信号的情况。仿真结果表明该算法是有效的,并具有很好的分离性能。