基于二阶段时间延迟的多产品生产系统生产与维修联合优化研究

针对多产品生产部件串联系统的生产和维修问题进行了研究,提出了基于二阶段时间延迟的联合优化模型。首先,基于生产周期分段理论,将整个周期等分成若干单位时间段,生产与维修共用每段时间,且若干时间段后采取一次预防维修。其次,考虑生产系统的实际生产时间、可用生产时间和维修耗费时间,建立了生产计划与维修计划总成本模型。其中,维修计划考虑缺陷和故障维修费用、维修检查费用,以及非正常状态下设备运行可能产生的不合格产品损失费用;生产计划考虑生产成本、库存成本、延期未交货成本和维修停机后恢复生产的设备启动成本。最后,通过算例分析,计算最优预防维修周期和各单位时间段各产品产量,验证了模型的有效性。     

基于仿真的生产设备预防性维修周期研究

为了对生产系统中的设备故障加以有效的控制，从而减少设备故障的发生，文章对生产设备的预防性维修周期问题进行了研究。通过建立生产设备预防性维修的费用模型，利用仿真的方法对不同维修策略的预防性维修周期进行优化选择。该模型综合考虑了修复性维修成本、预防性维修成本和生产损失成本。最后以故障分布形式为威布尔分布的设备为例进行仿真实验，得出设备最优维修周期结果，并阐述了经济原则对预防性维修周期的影响。     

基于优化策略的串并联系统预防维修周期研究

为了进行预防维修,提高系统可靠性,对系统维修费用会随着维修次数的增加而上升问题,提出最小优化方法.针对工程中常用的串并联系统,在考虑故障率随维修次数变化的条件下,引入役龄回退因子,提出一种可靠度为约束的系统预防维修费用最小的优化模型,在运用遗传算法进行优化求解的基础上,研究了系统总维修费用随可靠度的变化率.为了更好地确保遗传算法获得全局最优解,在传统遗传算法的基础上采用了并行操作、保留最优个体等方法.通过实例验证了优化模型的正确性与可用性,对模型作进一步的扩展,还可用于更一般复杂的系统.     

热轧带钢轧制批量计划优化模型及算法

基于奖金收集车辆路径问题模型建立了热轧带钢生产批量计划多目标优化模型．模型综合考虑了生产工艺约束、用户合同需求以及综合生产指标优化等因素．利用加权函数法将多目标优化模型转换为单目标优化模型,针对模型特点设计了蚁群优化求解算法,算法中嵌入了单向插入和2-opt局部搜索过程．引用某钢铁企业热轧生产轧制批量计划编制的实际问题对模型和算法进行了验证,结果表明模型和算法的优化效果和时间效率是令人满意的．     

基于性能合同的多部件系统维修策略模型优化

针对多部件串联系统维修效率低下与供应商所获利润少的问题，考虑各部件间的经济相关性，提出基于性能合同的多部件系统的维修策略模型。首先，采用韦伯（Weibull）分布描述系统各部件的使用寿命规律，并通过判断各部件使用度与预防性维修阈值和机会维修阈值的关系来实施不同的维修策略；其次，计算单位更新周期内的各维修活动概率和对应维修次数，以供应商利润最大化为目标，以预防性维修阈值和机会维修阈值为决策变量，建立基于性能合同的多部件系统的维修策略模型；最后，利用灰狼优化（GWO）算法求解该模型。通过算例分析得出与遗传（GA）算法、粒子群优化（PSO）算法相比，灰狼优化算法在准确率上分别提高了22.6%和7.6%；基于线性收益函数，所提绩效模型的利润率高达25.3%，相较于传统成本模型提高了5.2%。基于性能合同的多部件系统维修策略优化模型和算法可以有效解决供应商维修质量与效率低下问题，为供应商和运营商共同制定维修合同提供依据。     

基于双层规划的多供应商物料配送期量优化

为有效解决多供应商单制造商构成的二级供应链中供应商配送批量不经济、配送时间无序导致物流成本高和卸货拥堵等问题,建立多供应商配送期量的双层规划模型.上层模型从库存与配送联合优化视角,考虑供应商配送批量经济性,以供应链物流总成本最低为目标,确定最优配送批量;下层模型基于上层优化结果,考虑制造商生产时序性,以供应商时间惩罚成本最小化为目标,确定供应商配送时间序列.采用遗传算法和动态规划相结合的方法求解上下层模型,得到供应商最优配送期量标准.通过实例运用,验证了模型与算法的有效性及可行性.     

基于双层规划的多供应商物料配送期量优化

为有效解决多供应商单制造商构成的二级供应链中供应商配送批量不经济、配送时间无序导致物流成本高和卸货拥堵等问题,建立多供应商配送期量的双层规划模型.上层模型从库存与配送联合优化视角,考虑供应商配送批量经济性,以供应链物流总成本最低为目标,确定最优配送批量;下层模型基于上层优化结果,考虑制造商生产时序性,以供应商时间惩罚成本最小化为目标,确定供应商配送时间序列.采用遗传算法和动态规划相结合的方法求解上下层模型,得到供应商最优配送期量标准.通过实例运用,验证了模型与算法的有效性及可行性.     

基于扩展基本时段法的随机回收率ELSPR

针对存在于制造、再造混合生产系统的批量调度问题,研究旧产品回收率随机的情况下,考虑旧产品回收的多产品经济批量调度问题。基于扩展基本时段法综合考虑制造新品和再造产品的批量调度,构建以单位总成本最小为目标的优化模型。提出的改进型遗传算法对模型求解,能避免不可行解的产生。分别比较考虑和不考虑旧产品废弃处置两种情况下,该算法和Teunter方法的优化效果,结果表明提出的算法能进一步降低成本并保证最优解可行。     

可用度约束条件下的设备不完美预防维修策略

针对2M1B生产系统,基于设备实际维修情况,提出了故障设备不完美预防维修策略。首先,考虑设备随时间不断劣化的情况,基于准更新过程,建立了生产周期内设备随机故障次数的表达式,计算了设备维修总费用。其次,通过分析缓冲区内库存的变化轨迹,以生产周期内设备随机故障次数为基础,计算了缓冲区库存费用,综合设备维修费用和缓冲区库存费用,构建了周期内生产总成本模型。以满足系统最低要求的可用度水平为约束条件,以预防维修周期和缓冲区库存量为决策变量,以生产周期内单位时间总成本为目标函数,通过离散迭代算法获得最优预防维修周期和此周期下的最佳缓冲区库存量。最后,通过数值分析验证了模型的有效性,为制定最佳维修策略提供了有效依据。     

基于灾变机制的预防性维护和生产调度集成优化方法

为了解决生产车间中多品种任务的生产调度与预防性维护集成优化问题,综合考虑其加工顺序、生产批量及预防性维护策略等要素,在订单充足的前提下,以总制造成本和加工时间最小化为联合优化目标,建立了生产调度与预防性维护集成优化模型。针对模型特点,在非支配排序遗传算法框架的基础上,基于灾变机制和荣誉空间,引入截断和拼接操作算子,提出一种变长度染色体单亲遗传算法对模型进行求解,并在不同参数条件和问题规模下,通过仿真实验验证了该算法解决复杂生产任务调度和预防性维护集成优化问题的有效性。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate