Operation of superconducting fault current limiter using vacuum interrupter driven by electromagnetic repulsion force for commutating switch

Using conventional high‐temperature superconducting wire, a model superconducting fault current limiter (SFCL) is made and tested. Solenoid coil using Bi2223 silver sheath wire is so made that inductance is as small as possible and a vacuum interrupter is connected in series to it. A conventional reactor coil is connected in parallel. When the fault current flows in this equipment, superconducting wire is quenched and current is transferred into the parallel coil because of voltage drop of superconducting wire. This large current in parallel coil actuates magnetic repulsion mechanism of vacuum interrupter. Due to opening of vacuum interrupter, the current in superconducting wire is broken. By using this equipment, current flow time in superconducting wire can be easily minimized. On the other hand, the fault current is also easily limited by large reactance of parallel coil. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 52–61, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20315     

基于ZMP的双足机器人稳定性分析

引入双足机器人研究中一个重要物理量——零力矩点ZMP（zero Moment Point）,研究其计算和测量方法,利用其分析双足机器人在单腿和双腿支撑时的作用范围,最后在二维和三维平面内对机器人的ZMP计算进行探讨,为稳定步态的设计做了理论铺垫。     

基于统计特征和马尔可夫特征的图像拼接盲检测

数字图像真实性检测在司法鉴定等领域有着重要的作用.常见的图像拼接篡改会降低图像像素直接的相关性,这可以通过一些统计特征反映出来.采用特征提取-分类的方法,提取矩特征、基于二维相位一致性的统计特征,结合DCT域的马尔可夫特征,利用SVM分类器进行分类,实现了拼接图像的盲检测.实验结果表明,该方法有较好的鉴别准确率,可达91.75%.     

基于AutoCAD计算截面对任意轴的静距和惯性矩的程序设计

本文以二维绘图软件AutoCAD为平台,利用VBA开发工具,依据平面图形的平行移轴公式、转轴公式,实现了计算截面对任意轴的静距和惯性矩的程序设计。从而简化了计算过程,减少重复性工作。     

Application of maximum entropy principle for reliability-based design optimization

The maximum entropy principle (MEP) is used to generate a natural probability distribution among the many possible that have the same moment conditions. The MEP can accommodate higher order moment information and therefore facilitate a higher quality PDF model. The performance of the MEP for PDF estimation is studied by using more than four moments. For the case with four moments, the results are compared with those by the Pearson system. It is observed that as accommodating higher order moment, the estimated PDF converges to the original one. A sensitivity analysis formulation of the failure probability based on the MEP is derived for reliability-based design optimization (RBDO) and the accuracy is compared with that by finite difference method (FDM). Two RBDO examples including a realistic three-dimensional wing design are solved by using the derived sensitivity formula and the MEP-based moment method. The results are compared with other methods such as TR-SQP, FAMM + Pearson system, FFMM + Pearson system in terms of accuracy and efficiency. It is also shown that an improvement in the accuracy by including more moment terms can increase numerical efficiency of optimization for the three-dimensional wing design. The moment method equipped with the MEP is found flexible and well adoptable for reliability analysis and design.     

Orthogonal variant moments features in image analysis

Moments are statistical measures used to obtain relevant information about a certain object under study (e.g., signals, images or waveforms), e.g., to describe the shape of an object to be recognized by a pattern recognition system. Invariant moments (e.g., the Hu invariant set) are a special kind of these statistical measures designed to remain constant after some transformations, such as object rotation, scaling, translation, or image illumination changes, in order to, e.g., improve the reliability of a pattern recognition system. The classical moment invariants methodology is based on the determination of a set of transformations (or perturbations) for which the system must remain unaltered. Although very well established, the classical moment invariants theory has been mainly used for processing single static images (i.e. snapshots) and the use of image moments to analyze images sequences or video, from a dynamic point of view, has not been sufficiently explored and is a subject of much interest nowadays. In this paper, we propose the use of variant moments as an alternative to the classical approach. This approach presents clear differences compared to the classical moment invariants approach, that in specific domains have important advantages. The difference between the classical invariant and the proposed variant approach is mainly (but not solely) conceptual: invariants are sensitive to any image change or perturbation for which they are not invariant, so any unexpected perturbation will affect the measurements (i.e. is subject to uncertainty); on the contrary, a variant moment is designed to be sensitive to a specific perturbation, i.e., to measure a transformation, not to be invariant to it, and thus if the specific perturbation occurs it will be measured; hence any unexpected disturbance will not affect the objective of the measurement confronting thus uncertainty. Furthermore, given the fact that the proposed variant moments are orthogonal (i.e. uncorrelated) it is possible to considerably reduce the total inherent uncertainty. The presented approach has been applied to interesting open problems in computer vision such as shape analysis, image segmentation, tracking object deformations and object motion tracking, obtaining encouraging results and proving the effectiveness of the proposed approach.     

Maximum entropy membership functions for discrete fuzzy variables

Due to the deficiency of information, the membership function of a fuzzy variable cannot be obtained explicitly. It is a challenging work to find an appropriate membership function when certain partial information about a fuzzy variable is given, such as expected value or moments. This paper solves such problems for discrete fuzzy variables via maximum entropy principle and proves some maximum entropy theorems with certain constraints. A genetic algorithm is designed to solve the general maximum entropy model for discrete fuzzy variables, which is illustrated by some numerical experiments.     

Flux limiters fourth and sixth order high resolution method for hyperbolic conservation laws

This paper presents new fourth and six order accurate explicit finite difference scheme for hyperbolic conservation laws. The technique of obtaining high resolution, total variation non increasing oscillation free and explicit scalar difference scheme is derived by adding multi-limiters of antidiffusive flux to a first order scheme.     

某型飞机模糊极限状态限制器的设计

本文提出了一种基于模糊控制的某型飞机极限状态限制器的设计方法。该方法将模糊控制函数的优化和模糊控制系统增益自适应调整集中于一体,可大大改善系统的品质和适应能力。在系统设计中,比例因子的最小二乘法估计用于优化控制规则,论域的在线自调整可以消除模糊化过程中所导致的信息丢失,积分抑制策略则是为了提高稳态精度、增强适应性和进一步抑制超调。在全飞行包线的数字仿真结果表明,本文提出的模糊控制方法获得了良好的控制效果。