基于动态集成制造系统的代理协商机制的研究

介绍动态集成制造系统的概念及其代理结构,在此基础上分析代理协商的要素,对代理之间的协议进行了改进,并对影响协商决策的因素进行了探讨。     

柔性作业车间动态调度问题研究

针对车间调度问题柔性化、动态化的特点,对柔性作业车间动态调度问题进行了研究。构建了柔性作业车间动态调度数学模型,给出了基于周期与事件驱动的滚动窗口再调度策略,通过更新窗口工件集信息,运用调度模型及遗传算法实时给出再调度优化方案。同时,对求解的遗传算法进行了设计。最后,通过一个应用算例验证了动态调度模型、调度策略及算法的有效．陆和可行性。     

多品种多工艺车间调度建模、分析与优化

在分析国内外多智能体(Multi-Agent)建模、调度研究现状的基础上,对多品种多工艺车间物流系统进行研究.重点介绍了调度模块子系统这部分,并以某公司为例,运用调度规则对该公司两个车间布置方案进行调度研究,分析调度结果并进行优化布置.     

建立抢占式作业车间调度系统减少交货期惩罚

本文研究了交货期窗口下的抢占式作业车间调度问题。提前或拖期完工带有惩罚。利用多agent理论,设计了基于多agent的抢占式作业车间调度系统,将平均提前或拖期惩罚作为目标函数。首先,建立了由工件agent、生产单元agent和全局agent构成的抢占式作业车间调度系统,采用权重式的调度策略。然后,利用仿真软件Arena对抢占式作业车间调度系统进行了建模和仿真实验。在不同工期紧迫系数下的环境下进行仿真实验,并将调度结果与利用SPT、EDD、ATC等经典的分派规则得到的结果进行比较,充分证明了所提方法的有效性。     

基于Quest的车间物流建模和仿真

在生产线规划设计过程中,通过计算机仿真,可以在规划、设计阶段就对生产线系统的静、动态性能进行充分的预测,以便尽早地发现系统布局、配置及调度控制策略方面的问题,从而更快、更好地改善系统设计。因此,利用Delmia/Quest,针对车间物流的建模和仿真等进行了探讨和分析。     

基于蚁群算法的车间生产调度模型的研究与应用

针对面向订单的车间生产调度问题的局限性,结合实际生产情况,建立了订单车间生产调度管理系统,并对调度算法模型进行了深入研究,提出了一种综合运用理想点求模与蚁群算法的订单多目标优化调度方法。以最小化设备资源利用总时间、最小化产品延迟交货总时间为目标,利用蚁群算法对企业生产能力范围内的订单进行多目标优化调度,调度报表为企业实际生产提供指导。该系统和方法在某重型机械集团公司进行应用,体现了减少劳动力投入、缩短生产周期的效果。     

基于知识管理的车间调度规划

在以销定产的生产模式下,为了充分利用制造资源,提升制造企业核心竞争力,根据制造车间生产特点,提出了制造车间生产抽象化模型。将车间资源进行了分类,根据制造车间特点归纳出调度时应服从的原则,指出调度应服从的整体经济原则。对制造车间agent建立与调度优化方法,构建调度数据采集和网络做了分析。为功能各异、数据结构不同的车间资源调度的建模提供参考。     

具有模糊加工时间的Flexible Job-Shop Scheduling问题的研究

采用梯形模糊数来表征柔性生产系统中的时间参数,并在此基础上对具有模糊加工时间的柔性作业车间最小化制造跨度调度问题进行了描述。然后给出了基于粒子群优化的柔性作业车间调度模型。最后通过实例验证了模型的有效性。     

基于eM-Plant的柔性生产调度仿真研究

车间生产调度是流水制造企业运行管理的核心,针对流水车间工件多样化、多机调度平行化的作业特点,在分析系统逻辑流程和运行机理的基础上,用em-plant软件建立仿真模型,通过SimTalk语言程序触发仿真事件和监控仿真状态。分析工件加工时间、到达率及加工工序对调度结果的影响,以零件平均等待时间、资源利用率和置信度为系统评价指标。仿真结果表明,在确定加工工序和加工时间条件下,生产调度方案是合理的。     

基于eM-Plant的柔性生产调度仿真研究

车间生产调度是流水制造企业运行管理的核心,针对流水车间工件多样化、多机调度平行化的作业特点,在分析系统逻辑流程和运行机理的基础上,用em-plant软件建立仿真模型,通过SimTalk语言程序触发仿真事件和监控仿真状态.分析工件加工时间、到达率及加工工序对调度结果的影响,以零件平均等待时间、资源利用率和置信度为系统评价指标.仿真结果表明,在确定加工工序和加工时间条件下,生产调度方案是合理的.     

Scheduling of re-entrant flow shops

We propose and develop a scheduling system for a very special type of flow shop. This flow shop processes a variety of jobs that are identical from a processing point of view. All jobs have the same routing over the facilities of the shop and require the same amount of processing time at each facility. Individual jobs, though, may differ since they may have different tasks performed upon them at a particular facility. Examples of such shops are flexible machining systems and integrated circuit fabrication processes. In a flexible machining system, all jobs may have the same routing over the facilities, but the actual tasks performed may differ; for instance, a drilling operation may vary in the placement or size of the holes. Similarly, for integrated circuit manufacturing, although all jobs may follow the same routing, the jobs will be differentiated at the photolithographic operations. The photolitho-graphic process establishes patterns upon the silicon wafers where the patterns differ according to the mask that is used.The flow shop that we consider has another important feature, namely the job routing is such that a job may return one or more times to any facility. We say that when a job returns to a facility it reenters the flow at that facility, and consequently we call the shop a re-entrant flow shop. In integrated circuit manufacturing, a particular integrated circuit will return several times to the photolithographic process in order to place several layers of patterns on the wafer. Similarly, in a flexible machining system, a job may have to return to a particular station several times for additional metal-cutting operations.These re-entrant flow shops are usually operated and scheduled as general job shops, ignoring the inherent structure of the shop flow. Viewing such shops as job shops means using myopic scheduling rules to sequence jobs at each facility and usually requires large queues of work-in-process inventory in order to maintain high facility utilization, but at the expense of long throughput times.In this paper we develop a cyclic scheduling method that takes advantage of the flow character of the process. The cycle period is the inverse of the desired production rate (jobs per day). The cyclic schedule is predicated upon the requirement that during each cycle the shop should perform all of the tasks required to complete a job, although possibly on different jobs. In other words, during a cycle period we require each facility to do each task assigned to it exactly once. With this requirement, a cyclic schedule is just the sequencing and timing on each facility of all of the tasks that that facility must perform during each cycle period. This cyclic schedule is to be repeated by each facility each cycle period. The determination of the best cyclic schedule is a very difficult combinatorial optimization problem that we cannot solve optimally for actual operations. Rather, we present a computerized heuristic procedure that seems very effective at producing good schedules. We have found that the throughput time of these schedules is much less than that achievable with myopic sequencing rules as used in a job shop. We are attempting to implement the scheduling system at an integrated circuit fabrication facility.     

An empirical analysis of job shop dispatch rule selection

Job shop scheduling usually includes the process of selecting dispatch rules for loading shops with work. Traditionally, dispatch rules have been formed on the basis of processing time, operating time, or queueing order. A job shop scheduling model was developed to include external factors (such as due dates), internal factors (e.g., capacity), as well as influence factors (e.g., job status). Based on the model developed in this report a survey of industrial engineers, shop foremen, and production control supervisors was undertaken to determine what dispatch rules experienced job shop schedulers would select and if the selection process could be influenced by schedule conditions (status) or other organizational factors. Results suggest that schedulers may be influenced by other factors. This article suggests a model for further research with respect to job shop scheduling.     

计划排产在卷烟生产中的应用研究

文章针对卷烟厂混合型的卷烟生产,采用车间调度问题的方法,系统分析了卷烟生产中卷包和制丝不同生产环节的特点,得到了它们适用的计划模型以及相适应的算法。根据研究开发的计划排产信息系统,通过在武汉卷烟厂的实际应用表明,该计划排产信息系统具有优化排产、计划冲突避免的优点,取得了较好的应用效果。     

Use of the net present value criterion in a random job shop where early shipments are forbidden

Both practitioners and researchers in the field of Operations Management have suggested that shop scheduling should be an integral component in both the strategic and tactical plans for an organization's assets. This paper examines the use of an accepted measure of return on assets, net present value (NPV), in a simulated shop scheduling environment where early shipment of jobs before their due dates is forbidden. In addition, early shipment of raw materials to the shop is also forbidden. This shop environment is consistent with the prevalent practice in industry of accepting orders only on a just-in-time basis to reduce purchased parts inventories. The NPV measure provides a means of balancing a variety of performance criteria that have been treated as separate objectives previously, including work-in-process inventory, finished goods inventory, mean flow time and mean tardiness, while also providing a means of measuring monetarily the value of various shop scheduling approaches.The NPV performance of priority scheduling rules and order release policies is measured in this research through the simulation of a random job shop under a variety of environmental conditions. It is found in a comparison of priority rules that use time-based information with those that use job value information that the Critical Ratio rule provides higher average performance than the three other rules used in the study. However, in some situations that are consistent with JIT practice, value-based priority rules also perform well. The use of a mechanism for delaying the release of jobs to each work center in the shop provided higher average NPV when shop utilization was set at a low level of 80%, while immediate release of work upon its arrival to the shop provided superior performance at a higher shop utilization level of 94%. While JIT materials delivery and costing yields higher NPV, it did not alter the relative ranking of priority rule/release policy combinations. In addition, it was found that environmental factors, including average job length, average number of tasks per job and level of tardiness penalty, resulted in greater variations in NPV performance than the institution of a JIT raw materials delivery policy.     

A framework for service enterprise workflow simulation with multi-agents cooperation

Process dynamic modelling for service business is the key technique for Service-Oriented information systems and service business management, and the workflow model of business processes is the core part of service systems. Service business workflow simulation is the prevalent approach to be used for analysis of service business process dynamically. Generic method for service business workflow simulation is based on the discrete event queuing theory, which is lack of flexibility and scalability. In this paper, we propose a service workflow-oriented framework for the process simulation of service businesses using multi-agent cooperation to address the above issues. Social rationality of agent is introduced into the proposed framework. Adopting rationality as one social factor for decision-making strategies, a flexible scheduling for activity instances has been implemented. A system prototype has been developed to validate the proposed simulation framework through a business case study.     

Dynamic decision-making for reliability and maintenance analysis of manufacturing systems based on failure effects

A framework for reliability and maintenance analysis of job shop manufacturing systems is proposed in this paper. An efficient preventive maintenance (PM) policy in terms of failure effects analysis (FEA) is proposed. Subsequently, reliability evaluation and component importance measure based on FEA are performed under the PM policy. A job shop manufacturing system is applied to validate the reliability evaluation and dynamic maintenance policy. Obtained results are compared with existed methods and the effectiveness is validated. Some vague understandings for issues such as network modelling, vulnerabilities identification, the evaluation criteria of repairable systems, as well as PM policy during manufacturing system reliability analysis are elaborated. This framework can help for reliability optimisation and rational maintenance resources allocation of job shop manufacturing systems.     

An empirical investigation of different strategies for material requirements planning

Master production scheduling, component lot sizing, and capacity requirements planning represent three important modules of material requirements planning (MRP) systems. Coordinating these three modules has been largely dependent on managerial judgment and experience. In this research, five different strategies for integrating these modules are empirically investigated. These strategies differ mainly in the extent to which the modules are coordinated. The impact of the shop, product, component and cost characteristics is measured by varying ten experimental factors. The research findings so obtained provide several guidelines on the effectiveness of each strategy in different environmental settings.     

An evaluation of overtime policies for a repair shop

This article presents the first attempt to develop and examine overtime policies for a repair shop environment. Overtime is used to augment repair capacity as needed to offset short-term demand fluctuations. If overtime provides sufficient additional repair capacity, it may be possible to reduce investment in spare parts inventory.The use of overtime in a repair shop requires managerial attention to several issues. In this article, the following five issues are examined: The relationship between overtime policies and spares stocking levels The timing of overtime—reactive or proactive The amount of overtime to use The level in the product structure at which overtime is most beneficial The priority scheduling and labor assignment policies usedSix overtime policies are developed that explore the above issues. These are examined using a simulation model of a hypothetical repair shop. Since the focus of the article is on overtime policies, a single labor assignment policy is used in conjunction with two priority scheduling rules.The results indicate that reactive overtime policies work well in this environment and overtime is most effective at the lowest level of the product structure, where repair times are relatively shorter. In addition, lowest level parts provide more usage flexibility to handle anticipated future failures.