Maintenance routing for train units: The interchange model

Train units need regular preventive maintenance. Given the train units that require maintenance in the forthcoming 1–3 days, the rolling stock schedule must be adjusted so that these urgent units reach the maintenance facility in time. In this paper, we present an integer programming model for solving this problem, give complexity results, suggest solution methods, and report our computational results based on practical instances of NS Reizigers, the main Dutch operator of passenger trains.     

Semidefinite Programs and Association Schemes

We consider semidefinite programs, where the matrices defining the problem all arise from some association scheme. We show that in this case the semidefinite program can be solved through an ordinary linear program. As an application, we consider the max-cut problem, where the underlying graph arises from an association scheme. Received: November 26, 1998; revised July 20, 1999     

体数据中边界点计算的新方法

为了提高三维重构的精度,分析了Marching Cubes方法所产生的误差,提出获得边界点的新方法.新方法依据阈值区分出边界内、边界外和边界像素,利用这3个像素的像素值来决定边界点的位置.并且针对边界点的位置,提出了三角形网格结构的调整方法.理论分析表明,当边界在像素级别上是直线段时,新方法能够直接计算出精确的边界点.区分等值点和边界点,基于边界点,给出了不同于MC方法的等值点计算方法.最后用CT数据实例比较了新方法和MC方法.     

A Region-Dividing Technique for Constructing the Sum-of-Squares Approximations to Robust Semidefinite Programs

In this technical note, we present a novel approach to robust semidefinite programs, of which coefficient matrices depend polynomially on uncertain parameters. The approach is based on approximation with the sum-of-squares polynomials, but, in contrast to the conventional sum-of-squares approach, the quality of approximation is improved by dividing the parameter region into several subregions. The optimal value of the approximate problem converges to that of the original problem as the resolution of the division becomes finer. An advantage of this approach is that an upper bound on the approximation error can be explicitly obtained in terms of the resolution of the division. A numerical example on polynomial optimization is presented to show usefulness of the present approach.      

Training GANs with centripetal acceleration

ABSTRACT

Training generative adversarial networks (GANs) often suffers from cyclic behaviours of iterates. Based on a simple intuition that the direction of centripetal acceleration of an object moving in uniform circular motion is toward the centre of the circle, we present the Simultaneous Centripetal Acceleration (SCA) method and the Alternating Centripetal Acceleration (ACA) method to alleviate the cyclic behaviours. Under suitable conditions, gradient descent methods with either SCA or ACA are shown to be linearly convergent for bilinear games. Numerical experiments are conducted by applying ACA to existing gradient-based algorithms in a GAN setup scenario, which demonstrate the superiority of ACA.     

A Structure Exploiting Preprocessor for Semidefinite Programs Derived From the Kalman-Yakubovich-Popov Lemma

Semidefinite programs derived from the Kalman-Yakubovich-Popov (KYP) lemma are quite common in control and signal processing applications. The programs are often of high dimension which makes them hard or impossible to solve with general-purpose solvers. Here we present a customized preprocessor, KYPD, that utilizes the inherent structure of this particular optimization problem. The key to an efficient implementation is to transform the optimization problem into an equivalent semidefinite program. This equivalent problem has much fewer variables and the matrices in the linear matrix inequality constraints are of low rank. KYPD can use any primal-dual solver for semidefinite programs as an underlying solver.     

面向问题的系统化程序设计方法及其描述工具

一、引言 回顾以程序设计为核心的计算科学的研究、实践和教学,虽然有越来越多的人参与和林林总总的成果发表,而“程序设计危机”并没有得到根本的改善,为此,W.J,Dijistra重指出“真正讲授计算科     

一种用C++动态扩展C#程序的方法

提出一种用非托管C++(以下简称C++)动态扩展C#程序的方法。利用托管C++作为适配器,由C++类继承C#基类,并且获取C#程序提供的服务;将C++类利用托管C++作为适配器,通过C#基类的派生类提供给C#程序动态加载。实例表明该方法能够使C++编写的类继承C#程序中的类,获取C#程序提供的服务;并且使C#程序能够动态创建并调用C++类对象。该方法能够为C++源代码的重用、C++源代码与.NET平台语言的混合编程等提供解决方案。     

A linear algorithm for the pos/neg-weighted 1-median problem on a cactus

The 1-median problem on a network asks for a vertex minimizing the sum of the weighted shortest path distances from itself to all other vertices, each associated with a certain positive weight. We allow fornegative weights as well and devise an exact algorithm for the resulting ‘pos/neg-weighted’ problem defined on a cactus. The algorithm visits every vertex just once and runs thus in linear time. This research has been supported by the Spezialforschungsbereich F 003 ‘Optimierung und Kontrolle’, Projektbereich Diskrete Optimierung.     

利用计算机求解迷宫问题的新方法

通过对传统的“堆栈法”求解迷宫问题的思想及实现方法的分析 ,总结了传统方法在求解过程中存在的问题 ,提出了一种更为简便、易于理解、易于编程的算法     

一种多线程计算程序的机群移植方法

机群并行化应用程序的用户接口和编程方式多种多样，常常令用户望而却步，该文详细了一种从程序的目标代码着手，以ELF格式可执行文件PLT表项重定位为基础，利用多线程程序自身的并发和同步特征，让线程中的计算负载分布到机群各节点的移植技术，为用户提供透明的机群并行机制，提出并讨论了相应的Master-Worker(Task-Farming)计算通信模型以及调度策略，最后，通过实现该移植技术，分析基于BLAS库多线程矩阵乘法程序移植后的运行结果，验证了该模型的可行性和效率。     

A note on MULTIFIT scheduling for uniform machines

In this note, we derive the tight worst case bound √6/2+(1/2) ^k for scheduling with the MULTIFIT heuristic on two parallel uniform machines withk calls of FFD within MULTIFIT. When MULTIFIT is combined with LPT as an incumbent algorithm the worst case bound decreases to √2+1/2+(1/2) ^k . Partially supported by SFB F003 “Optimierung und Kontrolle”, Projektbereich Diskrete Optimierung and by the National Natural Science Foundation of China, Grant 19701028.     

An Efficient Method for Second Order Boundary Value Problems with Two Point Boundary Conditions

The discrete approximation to a second order boundary value problem by finite difference methods gives rise to a system with a coefficient matrix which is typically banded. Several articles discuss the solution of such systems. Here the efficient method is based on the idea of a system perturbation followed by corrections and is competitive with standard methods     

一种解决移动agent通信失效问题的方法

介绍了移动agent的特点,并分析了移动agent特有的通信失效问题产生的原因,针对这一问题提出了解决的方法,并用ibm aglet编程实现了通信中心的模型,最后对这一模型进行了测试,说明了这一方法确实能解决移动agent的通信失效问题。     

Can linear programs be used to test global optimization algorithms?

The paper contains critical remarks on global optimisation algorithms published by R. Horst and N. V. Thoai.     

一种求解与/或树的Petri网方法

研究了用Petri网求解人工智能中与/或树的问题,提出了一种把与/或树转换成相应的Petri网,并通过其逆网求得原与/或树的解树的方法,可进而利用模糊Petri网的推理得到与/或树的最优解树。该方法直观高效,拓宽了Petri网的应用领域。     

基于MCX314as的运动控制器设计

文章介绍了用C8051F120单片机和MCX314as组成运动控制器的方案.该方案应用存储器扩展的方法为运动控制芯片MCX314as和液晶显示模块MT22G06B的内部寄存器分配地址空间.从而实现C8051F120单片机对运动控制芯片和液晶模块的控制作用.文章还给出了MCX314和MT22G06B的驱动程序架构.     

A Dual Framework for Lower Bounds of the Quadratic Assignment Problem Based on Linearization

A dual framework allowing the comparison of various bounds for the quadratic assignment problem (QAP) based on linearization, e.g. the bounds of Adams and Johnson, Carraresi and Malucelli, and Hahn and Grant, is presented. We discuss the differences of these bounds and propose a new and more general bounding procedure based on the dual of the linearization of Adams and Johnson. The new procedure has been applied to problems of dimension up to , and the computational results indicate that the new bound competes well with existing linearization bounds and yields a good trade off between computation time and bound quality. Received: February 5, 1999; revised August 24, 1999     

Lattice-valued fuzzy frames

In this paper we aim to introduce the concept of lattice-valued fuzzy frame or L-fuzzy frame, related to traditional frames analogously to how L-fuzzy (resp. L-fuzzifying) topological spaces related to L-topological spaces (resp. traditional topological spaces). Some properties of L-fuzzy frames are introduced.     

一种基于最小冲突集的约束冲突消解方法

为了在协同设计中建立以人为核心的冲突消解方法,使设计者在约束冲突发生时,对约束信息之间的制约关系有较清晰的把握,合理地消解冲突,提取最小冲突集是有效的方法。该文在分析最小冲突集特征和交边算法的基础上,给出了提取最小冲突集的方法,并结合一个算例说明最小冲突集在设计者参与下对识别、消解冲突的有效性。