The two-machine open-shop problem with unit-time operations and time delays to minimize the makespan

This paper addresses the problem of scheduling unit-time operations with integral and non-negative time delay considerations on a two-machine open-shop environment. The criterion to minimize is the makespan. Two well solvable cases and two approximation algorithms, with their worst-case analyses, are presented.     

Transversal homoclinic orbits for higher dimensional difference equations

In this paper, we use the functional analytic method (theory of exponential dichotomies and Liapunov-Schmidt method) to study the homoclinic bifurcations of higher dimensional difference equations in a degenerate case. We obtain a Melnikov vector mapping for difference equations with the help of which the existence of transversal homoclinic orbits can be detected.     

“Visual C++语言”课程教学改革研究

本文针对"Visual C++语言"课程教学现状,提出了以专业工程案例为中心的教学模式。教学过程中,笔者为相关教学内容精选了与之配套的教学案例,使得教学内容具有了明显的专业特色。实践证明,案例教学模式能够提升学生对专业知识的应用能力,明显改善教学效果。     

闭环伺服系统中的“一题多解”——数控机床典型维修案例分析

随着数控技术的高速发展,作为机电一体化的数控机床得到迅速发展和广泛的应用。本文从伺服系统概念入手,重点分析闭环伺服系统的控制原理,并结合数控维修实践中的典型故障案例,尤其是同一报警现象而不同故障原因及不同解决途径的典型维修案例进行论述。     

Toward direct determination of conformations of protein building units from multidimensional NMR experiments I. A theoretical case study of For‐Gly‐NH2 and For‐L‐Ala‐NH2

NMR chemical shielding anisotropy tensors have been computed, employing several basis sets and the GIAO‐RHF and GIAO‐MP2 formalisms of electronic structure theory, for all the atoms of the five and nine typical backbone conformers of For‐Gly‐NH₂ and For‐L ‐Ala‐NH₂, respectively. Multidimensional chemical shift plots, as a function of the respective backbone fold, have been generated for both peptide models. On the 2D ¹H^NH‐¹⁵N^NH and ¹⁵N^NH‐¹³C^α plots the most notable feature is that at all levels of theory studied the backbone conformers cluster in different regions. Computed chemical shifts, as well as their averages, have been compared to relevant experimental values taken from the BioMagnetic Resonance Bank (BMRB). At the highest levels of theory, for all nuclei but the amide protons, deviations between statistically averaged theoretical and experimental shifts are as low as 1–3%. These results indicate that chemical shift information from selected multiple‐pulse NMR experiments (e.g., 2D‐HSQC and 3D‐HNCA) could directly be employed to extract folding information for polypeptides and proteins. © 2000 John Wiley & Sons, Inc. J Comput Chem 21: 882–900, 2000     

A2B模型的受迫振动模式研究的注记

讨论了A2B模型的受迫振动模式研究中的一些问题.     

航空电源产品金属机箱的电磁兼容性设计(上)

对航空电源系统中的电子产品来说,其金属机箱除了具有机械支撑和保护作用外,还应具有一定的屏蔽效能来提高电子产品的电磁兼容性.本文对航空电源产品金属机箱的电磁兼容性设计进行了分析研究,并以产品实际的电磁兼容性测试为例来说明金属机箱电磁兼容性设计对电子产品可靠性产生的重要意义,最后对金属机箱屏蔽效能测试的原理和方法进行了介绍.     

融合STEM与OBE理念的微机继电保护案例教学改革

微机继电保护作为电网安稳运行的关键环节,需要符合新工科背景和工程教育专业认证人才培养要求的教学方法。为此提出一种融合STEM与OBE理念的微机继电保护案例教学法,对微机继电保护复杂理论体系进行了模块化研究,并以工程案例为载体阐明微机继电保护运行机理,实现教学主体由教师向学生的转变。实践证明,所提方法能够有效提高教学效率,确保工程能力产出,有助于微机继电保护课程建设。     

一种软件需求变化追踪方法

有效的软件变化追踪方法是实施软件演化的关键.基于需求信息传播与建模、需求变化信息传播路径和需求变化信息跟踪方法三个层面,阐述了软件变化跟踪的整体过程框架;给出了基于变化起源跟踪矩阵、变化对象跟踪矩阵、变化构件跟踪矩阵、以及可达矩阵的功能变化传播记录方法;凭借矩阵运算,描述了功能变化跟踪的具体实现,并给出了实施变化所付出代价高低的初步判定方法.对软件维护甚至软件演化研究具有一定的借鉴意义.     

Solving a chemical batch scheduling problem by local search

In this paper the following chemical batch scheduling problem is considered: a set of orders has to be processed on a set of facilities. For each order a given amount of a product must be produced by means of chemical reactions before a given deadline. The production consists of a sequence of processes whereby each process has to be performed by one facility out of a given subset of facilities allowed for this process. The processing times depend on the choice of the facility and the processing is done in batch mode with given minimum and maximum sizes. The problem is to assign the processes to the facilities, splitting them into batches, and scheduling these batches in order to produce the demands within the given deadlines. For the scheduling part of the problem we present an approach based on the following steps. First, a procedure to calculate the minimum number of batches needed to satisfy the demands is presented. Based on this, the given problem is modeled in two different ways: as a general shop scheduling problem with set-up times or as scheduling problem with positive time-lags. Finally, a two-phase tabu search method is presented which is based on the two different formulations of the problem. The method is tested on some real world data. This revised version was published online in June 2006 with corrections to the Cover Date.