Single machine scheduling with a restricted rate‐modifying activity

In this paper we consider the problem of scheduling a set of jobs on a single machine on which a rate‐modifying activity may be performed. The rate‐modifying activity is an activity that changes the production rate of the machine. So the processing time of a job is a variable, which depends on whether it is scheduled before or after the rate‐modifying activity. We assume that the rate‐modifying activity can take place only at certain predetermined time points, which is a constrained case of a similar problem discussed in the literature. The decisions under consideration are whether and when to schedule the rate‐modifying activity, and how to sequence the jobs in order to minimize some objectives. We study the problems of minimizing makespan and total completion time. We first analyze the computational complexity of both problems for most of the possible versions. The analysis shows that the problems are NP‐hard even for some special cases. Furthermore, for the NP‐hard cases of the makespan problem, we present a pseudo‐polynomial time optimal algorithm and a fully polynomial time approximation scheme. For the total completion time problem, we provide a pseudo‐polynomial time optimal algorithm for the case with agreeable modifying rates. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005     

影响高层建筑内热烟气流动的因素分析

分析影响高层建筑内热烟气流动的五种因素,即烟囱效应、外部风压作用、高温烟气浮力作用、气体受热膨胀作用、通风和空调系统作用。这有助于对高层建筑内热烟气流动规律的研究,并进一步对高层建筑内热烟气的管理与控制提供依据。     

棱纹面与洛仑兹力对湍流边界层特性影响的比较

用氢气泡技术对棱纹面平板以及施加行波式洛仑兹力的平板水边界层开展流动显示实验研究,探讨棱纹面与行波式洛仑兹力影响湍流边界层相干结构的作用机理.实验结果表明,棱纹面与洛仑兹力促进了边界层由层流向湍流的转捩;而对于湍流边界层,在一定的无量纲参数范围内棱纹面与行波式洛仑兹力都能实现边界层的局部减阻,相应地湍流边界层粘性底层低速条带平均间距有所增加.     

凝结水泵三维流场数值模拟与分析

为深入理解和分析电站凝结水泵性能,采用计算流体力学方法(CFD)对其内部复杂的三维流场进行了数值模拟与分析.首先,建立了某三级凝结水泵各部件几何模型,并对其进行网格划分.通过求解RANS方程对凝结水泵内部三维流场进行数值求解,湍流流动采用SST模型进行模拟.计算得到该泵若干工况下的扬程和功率等性能参数和泵内部流动特征,计算结果与试验数据吻合很好.模拟结果及分析表明:采用CFD方法模拟结构复杂的凝结水泵内部流动和进行性能预报是可行的.通过内流场分析还发现导叶体等部件的设计有可改进之处.     

Efficiency of equilibria in restricted uniform machine scheduling with total weighted completion time as social cost

In the last decade, there has been much progress in understanding scheduling problems in which selfish jobs aim to minimize their individual completion time. Most of this work has focused on makespan minimization as social objective. In contrast, we consider as social cost the total weighted completion time, that is, the sum of the agent costs, a standard definition of welfare in economics. In our setting, jobs are processed on restricted uniform parallel machines, where each machine has a speed and is only capable of processing a subset of jobs; a job's cost is its weighted completion time; and each machine sequences its jobs in weighted shortest processing time (WSPT) order. Whereas for the makespan social cost the price of anarchy is not bounded by a constant in most environments, we show that for our minsum social objective the price of anarchy is bounded above by a small constant, independent of the instance. Specifically, we show that the price of anarchy is exactly 2 for the class of unit jobs, unit speed instances where the finite processing time values define the edge set of a forest with the machines as nodes. For the general case of mixed job strategies and restricted uniform machines, we prove that the price of anarchy equals 4. From a classical machine scheduling perspective, our results establish the same constant performance guarantees for WSPT list scheduling. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2012     

基于CANoe的战车综合电子系统任务信息流测试与分析

针对某型战车综合电子系统特定任务模式下相关性能指标较低的问题,对该模式下系统内任务信息流进行规划和梳理,借助CANoe测试工具,以面向任务的角度,分析该任务模式下系统总线性能,提出优化方案,并就相关结论和方案的正确性进行实际测试验证,为探讨特定模式下系统总线性能提供借鉴。     

基于分布式数据流的的指控系统服务集成方法

针对SOA服务集成架构应用于军用指控系统遇到的问题,提出了一种基于分布式数据流的服务集成方法。其设计思想不同于现在常用的服务集成方法中采取的集中式数据流,该方法支持指控服务构件之间数据的直接通信,可避免集中式处理带来的通信瓶颈问题,提高了服务集成的性能,较好地适应了军用异构网络环境。     

Batch scheduling with step‐deteriorating processing times to minimize flowtime

Both topics of batch scheduling and of scheduling deteriorating jobs have been very popular among researchers in the last two decades. In this article, we study a model combining these two topics. We consider a classical batch scheduling model with unit‐jobs and batch‐independent setup times, and a model of step‐deterioration of processing times. The objective function is minimum flowtime. The optimal solution of the relaxed version (allowing non‐integer batch sizes) is shown to have a unique structure consisting of two consecutive decreasing arithmetic sequences of batch sizes. We also introduce a simple and efficient rounding procedure that guarantees integer batch sizes. The entire solution procedure requires an effort of O(n) (where nis the number of jobs.) © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2012     

维修任务调度的多目标决策模型

通过对维修调度问题进行分析,考虑到战斗力相关的多种目标因素,针对目前研究的目标单一,又未考虑武器的先进程度、配置等缺陷,就修复后的加权作战时间和装备尽可能少的延误数量双重目标加以研究,并给出了调度算法。从而弥补了这些缺陷,使调度更加合理。最后,算例表明模型的求解方法简单,计算时间较短,可有效地实现维修任务调度。     

A branch‐and‐price algorithm for parallel machine scheduling with time windows and job priorities

This paper presents a branch‐and‐price algorithm for scheduling n jobs on m nonhomogeneous parallel machines with multiple time windows. An additional feature of the problem is that each job falls into one of ρ priority classes and may require two operations. The objective is to maximize the weighted number of jobs scheduled, where a job in a higher priority class has “infinitely” more weight or value than a job in a lower priority class. The methodology makes use of a greedy randomized adaptive search procedure (GRASP) to find feasible solutions during implicit enumeration and a two‐cycle elimination heuristic when solving the pricing subproblems. Extensive computational results are presented based on data from an application involving the use of communications relay satellites. Many 100‐job instances that were believed to be beyond the capability of exact methods, were solved within minutes. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2006