Effective Fitness as an Alternative Paradigm for Evolutionary Computation I: General Formalism

In evolutionary computation the concept of a fitness landscape has played an important role, evolution itself being portrayed as a hill-climbing process on a rugged landscape. In this article we review the recent development of an alternative paradigm for evolution on a fitness landscape—effective fitness. It is shown that in general, in the presence of other genetic operators such as mutation and recombination, hill-climbing is the exception rather than the rule; a discrepancy that has its origin in the different ways in which the concept of fitness appears—as a measure of the number of fit offspring, or as a measure of the probability to reach reproductive age. Effective fitness models the former not the latter and gives an intuitive way to understand population dynamics as flows on an effective fitness landscape when genetic operators other than reproductive selection play an important role. Additionally, we will show that when the genotype-phenotype map is degenerate, i.e. there exists a synonym symmetry, it can be used to quantify the degree of symmetry breaking of the map, thus allowing for a quantitative explanation of phenomena such as self-adaptation, bloat and evolutionary robustness.     

变压器差动保护涌流制动原理分析

空充误动是变压器差动保护的一大难题，现有的涌流制动原理主要是二次谐波和波形对称。文中深入分析了这2种原理之间的内在联系，指出不同的转角方式对保护可靠性产生的影响。传统的Y侧转换方式下，两相涌流之差可能导致二次谐波减小，波形趋于对称，这2种原理均可能误动；D侧转换方式下，三相涌流将互相影响，难以确定谐波制动的比例。     

三相变压器励磁涌流及保护方案

针对近期基于波形对称原理的变压器差动保护频繁误动的现状，从三相变压器励磁涌流的产生机理入手，分析了波形对称原理与2次谐波制动原理的内在联系，结合目前流行的2种相位补偿方式，指出了传统采用相间差动的保护方案误动的根本原因。针对220 kV以上D侧套管内装设电流互感器的变压器，提出了一种采用相电流差动接线的保护方案。该方案在理论上克服了传统方案的全部弊端，并可实现真正的分相制动；缺点在于保护范围有所减小，需要其他保护来配合。     

Vector Symmetry Reduction

Symmetry reduction is an effective state-space reduction technique for model checking, and works by restricting search to equivalence class representatives with respect to a group of symmetries for a model. A major problem with symmetry reduction techniques is the time taken to compute the representative of a state, which can be prohibitive. In efficient implementations of symmetry reduction, a symmetry is applied to a state as a sequence of operations which swap component identities. We show that vector processing technology, common to modern computers, can be used to implement a vectorised swap operation, which can be incorporated into the representative computation algorithm to accelerate symmetry reduction. Via a worked example, we present details of this vector symmetry reduction method. We have implemented our techniques in the TopSpin symmetry reduction package for the Spin model checker, and present experimental results showing the speedups obtained via vectorisation for two case-studies running on a PowerPC vector processor.     

均质各向异性土层中轴对称渗流问题的分析

对于均质各向异性土层中的轴对称渗流问题,也同平面问题一样,可取缩放渗流场比尺的方法解题,但其结果不同于平面问题。按研究结果:如缩小径向尺度,则缩小后渗流场的等效渗透系数为横向渗透系数kh;如放大轴向尺度,则放大后渗流场的等效渗透系数为平均渗透系数√khkv。     

Generalized Serret-Andoyer Transformation and Applications for the Controlled Rigid Body

The Serret-Andoyer transformation is a classical method for reducing the free rigid body dynamics, expressed in Eulerian coordinates, to a 2-dimensional Hamiltonian flow. First, we show that this transformation is the computation, in 3-1-3 Eulerian coordinates, of the symplectic (Marsden-Weinstein) reduction associated with the lifted left-action of SO(3) on T*SO(3)—a generalization and extension of Noether's theorem for Hamiltonian systems with symmetry. In fact, we go on to generalize the Serret-Andoyer transformation to the case of Hamiltonian systems on T*SO(3) with left-invariant, hyperregular Hamiltonian functions. Interpretations of the Serret-Andoyer variables, both as Eulerian coordinates and as canonical coordinates of the co-adjoint orbit, are given. Next, we apply the result obtained to the controlled rigid body with momentum wheels. For the class of Hamiltonian controls that preserve the symmetry on T*SO(3), the closed-loop motion of the main body can again be reduced to canonical form. This simplifies the stability proof for relative equilibria , which then amounts to verifying the classical Lagrange-Dirichlet criterion. Additionally, issues regarding numerical integration of closed-loop dynamics are also discussed. Part of this work has been presented in LumBloch:97a. This revised version was published online in July 2006 with corrections to the Cover Date.     

小波变换在图形边缘检测中的应用

从小波变换的定义和性质出发，研究了它在图像识别和边缘检测中的基本原理及优越性能，并将其应用到测量扫描透镜对称度的实验数据处理当中，而且取得了令人满意的结果．     

二重积分的对称性及其应用

证明了二重积分的变量轮换对称性和奇偶对称性;在二重积分计算中,增强对称性的使用意识,利用对称性简化解题过程.     

D,yn11和Y,ynO结线变压器的对比分析

对比分析了Ｄ，Ｙｎ１１和Ｙ，ＹｎＯ结线两种变压器的优缺点，从而提出民用建筑应推广选用Ｄ，Ｙｎ１１结纡配电变压器的可行性和优越性。