基于GA-PLS和AdaBoost的故障诊断方法

提出一种基于GA-PLS和AdaBoost的液压系统故障诊断方法。该方法用遗传算法与偏最小二乘法相结合(Genetic algorithm-partial least squares,GA-PLS)的算法对初始特征向量进行筛选,提取出与故障信息相关程度高的特征向量,把该特征向量作为输入,运用AdaBoost(Adaptive Boost)方法建立分类器,以识别液压系统的工作状态和故障类型。对实验数据分析的结果说明,该方法能准确地选择出特征向量,并有效地应用于液压系统的故障诊断。     

基于AdaBoost和深度残差网络的时间序列分类

时间序列分类(TSC)是数据挖掘领域中重要且富有挑战性的问题之一.首先将时间序列数据按照Gramian Angular Summation/Difference Field(GASF/GADF)、Markov Transition Field(MTP)、Recurrence Plot(RP)四种方式编码成图像,然后利用...     

最佳费用流

建立赋模糊数为费用权的容量－－费用网络中,据模糊决策来求解最佳费用流的网络模型,并给出这一模型的相应算法。     

最大流问题的逆问题

讨论了最大流问题的逆问题,提出了ｆ＾０截的概念,给出并证明了逆问题有解的充要条件;当逆问题有解时,把逆问题转化为找一个容量网络的最小截的问题;最后,给出了一个复杂度为Ｏ（│Ｖ│＾３）的多项式算法。     

Mixed Convection Flow Past a Horizontal Plate: The Global Flow

The mixed convection flow past a horizontal plate which is aligned under a small angle of attack to a uniform free stream will be considered in the limit of large Reynolds number and small Richardson number. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

气固两相流和气液两相流的掺混问题

在工业生产中气固两相流和气液两相流的掺混是一个常见问题.在这个掺混流动过程中,颗粒团将形成,且在颗粒碰撞聚结效应和分裂效应相平衡时,颗粒团将具有稳定半径.本文引入了颗粒团线尺度数密度分布函数n(a,,t),从分子运动论的观点出发,导出了颗粒团线尺度数密度分布函数的控制方程.最后,在气相流速非常缓慢的情况下,得到了颗粒团平均稳定半径的表达式.     

考虑路损的最大流问题及其基本特征

本文给出了考虑流量损耗的最大流问题的数学模型,并阐明了该问题的几个基本特征.     

Poiseuille流的谱问题

对Poiseuille流问题的Orr-Sommerfeld方程严格求解.得到的正规解不含外来奇点.从而谱方程可作解析的显式分析.本文结果可以进一步讨论分岔解.     

The Spectral-Difference Method for Compressible Flow

A spectral-difference scheme is proposed for semi-periodic compressible flow with strict estimation.     

The Solution of Isentropic Transonic Flow

A general method for analysing mixed subsonic-supersonic flowshas been developed. It has been applied to the case of chokedisentropic flow in a convergent-divergent nozzle and the resultshave been compared with existing series solutions for simplegeometries; very good agreement has been found throughout theflow field. Good agreement has also been found with experimentalresults for the flow in nozzles of more complicated geometry.Some extensions of the method are mentioned such as the inclusionof boundary layer development and the analysis of flows withfree boundaries.     

流的Ω-极限集

本文讨论流的Ω－极限集的性质,推广了ＣｏｎｌｅｙＣ。在文［１］中的一些结果。     

双重介质分形油藏渗流问题

将油井有效半径引入双重介质分形油藏渗流问题的内边界之中,从而建立了双重介质分形油藏的一种渗流模型,并在考虑了井筒储集和表皮效应的情况求得了外边界为无限大、有界封闭和有界定压三种情况下双重介质分形油藏压力分布的精确解析表达式,利用拉氏数值反演Stehfest方法分析了双重介质分形油藏压力动态特征,讨论了各种参数对压力动态的影响。     

带模糊约束的最小费用流问题

本文首次提出了带模糊约束的最小费用流问题,建立了相应的数学模型并给出了求解这一模型的有关算法。最后,给出了一个具体实例。     

The KdV Equation in Stratified Fluid Flow

This paper describes a method for the formal derivation of the equation governing long waves on the surface of a shallow fluid which is stably and continuously stratified. By using a three variable expansion procedure involving the normal time scale together with two slow time scales suggested as a result of the formulation of the problem the governing equation is shown to be the ordinary Korteweg-de Vries equation.

AMS(MOS) CLASSIFICATION: 76D30, 35Q20, 35C20.     

强似梯度流的存在性

对于定义在拓扑空间上的流,我们证明了这个流限制在紧不变集上为强似梯度流的两个判定定理,推广了Conley的结果．当流的休止点都是孤立时,我们得到了它是强似梯度流的一个充要条件．     

The Heat Flow of the CCR Algebra

Let Pf(x) = –if'(x) and Qf(x) = xf(x) be the canonicaloperators acting on an appropriate common dense domain in L²(R).The derivations D_P(A) = i(PA–AP) and D_Q(A) = i(QA–AQ)act on the *-algebra A of all integral operators having smoothkernels of compact support, for example, and one may considerthe noncommutative ‘Laplacian’, L = + , as a linear mapping of A into itself. L generates a semigroup of normal completely positive linearmaps on B(L₂(R)), and this paper establishes some basic propertiesof this semigroup and its minimal dilation to an E₀-semigroup.In particular, the author shows that its minimal dilation ispure and has no normal invariant states, and he discusses thesignificance of those facts for the interaction theory introducedin a previous paper. There are similar results for the canonical commutation relationswith n degrees of freedom, where 1 n < . 2000 MathematicsSubject Classification 46L57 (primary), 46L53, 46L65 (secondary).     

带模糊约束的最大流问题

首次提出带模糊约束的最大流问题,并根据网络中的弧容量限制是否带有模糊性,分别建立数学模型,给出求解这两个模型的相应算法和有关实例。     

The Hyperbolic Geometric Flow on Riemann Surfaces

In this paper the authors study the hyperbolic geometric flow on Riemann surfaces. This new nonlinear geometric evolution equation was recently introduced by the first two authors, motivated by Einstein equation and Hamilton's Ricci flow. We prove that, for any given initial metric on ?² in certain class of metrics, one can always choose suitable initial velocity symmetric tensor such that the solution exists for all time, and the scalar curvature corresponding to the solution metric g _ij keeps uniformly bounded for all time; moreover, if the initial velocity tensor is suitably “large", then the solution metric g _ij converges to the flat metric at an algebraic rate. If the initial velocity tensor does not satisfy the condition, then the solution blows up at a finite time, and the scalar curvature R(t, x) goes to positive infinity as (t, x) tends to the blowup points, and a flow with surgery has to be considered. The authors attempt to show that, comparing to Ricci flow, the hyperbolic geometric flow has the following advantage: the surgery technique may be replaced by choosing suitable initial velocity tensor. Some geometric properties of hyperbolic geometric flow on general open and closed Riemann surfaces are also discussed.     

The Scenery Flow for Hyperbolic Julia Sets

We define the scenery flow space at a point z in the Julia setJ of a hyperbolic rational map T : C C with degree at least2, and more generally for T a conformal mixing repellor. We prove that, for hyperbolic rational maps, except for a fewexceptional cases listed below, the scenery flow is ergodic.We also prove ergodicity for almost all conformal mixing repellors;here the statement is that the scenery flow is ergodic for therepellors which are not linear nor contained in a finite unionof real-analytic curves, and furthermore that for the collectionof such maps based on a fixed open set U, the ergodic casesform a dense open subset of that collection. Scenery flow ergodicityimplies that one generates the same scenery flow by zoomingdown towards almost every z with respect to the Hausdorff measureH^d, where d is the dimension of J, and that the flow has a uniquemeasure of maximal entropy. For all conformal mixing repellors, the flow is loosely Bernoulliand has topological entropy at most d. Moreover the flow atalmost every point is the same up to a rotation, and so as acorollary, one has an analogue of the Lebesgue density theoremfor the fractal set, giving a different proof of a theorem ofFalconer. 2000 Mathematical Subject Classification: 37F15, 37F35, 37D20.     

On The Atmospheric Boundary Layer Flow Modelling

The paper presents a mathematical and numerical investigation of the flow in the atmospheric boundary layer (ABL) over complex topography. The flow is supposed to be viscous, incompressible, turbulent and stationary. Two different mathematical–numerical approaches are briefly mentioned. Both models have been used to simulate a flow and pollution dispersion over a complex surface coal field in the North Bohemia which is supposed to be partially covered by a high forest stand. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)