CONWIP生产控制方法

介绍ＣＯＮＷＩＰ生产控制方法的产生,工作原理,优点,研究现状及未来的研究方向。有效的生产控制系统是指在正确的时间,以有竞争的价格生产出正确的产品,继ＭＲＰ－Ⅱ和Ｋａｎｂａｎ之后,ＣＯＮＷＩＰ生产控制方法引起人们的广泛重视,成为生产控制方法研究的热点。     

WWW文档协同写作系统中通信中间件的设计与实现

ＷＷＷＤＯＣ是一个基于ＴＣＰ／ＩＰ协议的分布式协同写作系统,ＤＯＣＯＭ作为通信中间件将客户和服务器有机地联系起来。本文分析了ＤＯＣＯＭ的设计任务和目标,介绍ＤＯＣＯＭ的对象模型、通信接口和公用服务。     

LONWORKS网络的新技术

对ＬＯＮＷＯＲＫＳ网络的最新技术－－ＬＯＮＷＯＲＫＳ网络服务ＬＮＳ及其作为对ＬＮＳ访问接口的ＬＯＮＷＯＲＫＳ元件体系结构ＬＣＡ作了描述，同时对ＬＮＳ的优点作了概括。     

基于对象／Agent的计算机集成过程运行系统建模研究

运用面向对象方法学、ＫＡＤＳ原理以及分布式人工智能领域的Ａｇｅｎｔ概念,用对象描述过程领域,用Ａｇｅｎｔ描述过程运行决策系统,建立一种基于对象／Ａｇｅｎｔ的计算机集成过程运行（ＣＩＰＯ）系统模型。通过开发实例系统ＴＥ－ＣＩＰＯＳ,说明了该模型的应用及优点。     

IP电话及其在线缆调制解调系统上的应用

ＩＰ电话采用的信道复用和基于分组交换的传输技术提高了线路传输利用率。ＨＦＣ网双向改造的完成和 ＤＯＣＳＩＳ的不断完善为开展 ＩＰ电话增值业务提供了理想的接入网平台。本文研究了ＩＰ电话技术的现状、发展趋势,以及 ＩＰ电话的标准 Ｈ．３２３规约、 ＳＩＰ、 ＭＧＣＰ、 ＲＴＰ／ＲＴＣＰ和ＲＳＶＰ。最后介绍了一种国内开发的 ＨＦＣ网上ＩＰ电话应用系统。     

业界性能最高的路由器

思科系统推出两款业界性能最高的路由器──Ｃｉｓｃ１２４１０和Ｃｉｓｃｏ１２４１６。基于这两款路由器,服务供应商可以将其网络扩展到帽子光纤网的速度,为下一代ＩＰ服务提供足够的带宽。Ｃｉｓｃｏ１２４００系列路由器采用业界独一无二的分布式体系结构,可以提供ＩＰ＋光纤的网络基础和服务构建模块,是构建１０ＧｂｐｓＩＰ基础设施最佳的平台。 思科还为这两款路由器配套推出了单端口ＯＣ－１９２ｃ／ＳＴＭ－６４ｃ ＰＯＳ（Ｐａｃｋｅｔ ｏｖｅｒＳＯＮＥＴ／ＳＤＨ）线路接口卡、四端口ＯＣ－４８ｃ／ＳＴＭ－１６ｃ ＰＯＳ线…     

一个基于TCP／IP网络的计算机会议系统的设计与实现

在对ＴＣＰ／ＩＰ协议进行分析的基础上，本文讨论了在实现计算机会议时应采用的客户机／服务器通信模式及ＵＤＰ通信技术，并以ＷＩＮＤＯＷＳ环境下的ＴＣＰ／ＩＰ协议－ＷＩＮＳＯＣＫ编程接口，实现了一个基于文本的计算机会议系统。     

基于TMN逻辑分层的CORBA网管与传统网管互操作机制研究

文章首先介绍了当前网管技术的发展情况,指出分布对象技术是网管的发展方向。但在相当长的时间内,仍是 ＳＮＭＰ、ＣＭＩＰ和 ＣＯＲＢＡ共存的局面。随后针对 ＯＭＧ组织提出的 ＣＯＲＢＡ－ｂａｓｅｄ ＴＭＮ体系,提出了基于 ＴＭＮ逻辑分层的ＣＯＲＢＡ网管与传统网管工操作机制,分析了这种方法的特点及应用情况。     

一个基于TCP/IP网际的计算机会议系统的设计与实现

在对ＴＣＰ／ＩＰ协议进行分析的基础上，本文讨论在实现计算机会议时应采用的客户机／服务器通信模式及ＵＤＰ通信技术，并以ＷＩＮＤＯＷＳ环境下的ＴＣＰ／ＩＰ协议———ＷＩＮＳＯＣＫ编程接口，实现了一个基于文本的计算机会议系统。     

IP网络上的分布式多媒体系统的实现原理与模型

阐述在 ＩＰ网络上实现分布式多媒体系统的实现原理,给出一个基于 ＣＯＲＢＡ的分布式多媒体对象的结构模型。最后介绍 Ｃｉｓｃｏ公司的分布式多媒体应用系统 ＩＰ／ＴＶ的结构、功能与特点。     

基于遗传算法和排队网的串联CONWIP系统流通卡数的确定方法

在CONWIP(constant work in process)系统中,流通卡数是系统有效运行的关键因 素.文中针对串联CONWIP系统,提出了非线性整数规划模型和排队网模型相结合的问题描述 模型,以及遗传算法与排队网络分析相结合的问题求解算法.实例仿真验证了该方法的有效性.     

A performance comparison between Kanban and CONWIP controlled assembly systems

There exists controversy on the superiority of logistics control systems. Kanban and CONWIP systems are focused on and analyzed in this paper. CONWIP is a well-known production control system, and some papers have shown it has better performance than the Kanban system. Our research shows that the Kanban is more flexible for the assembly system under concern with respect to a given objective than the CONWIP. In some cases, if the number of kanbans at each manufacturing/assembling station is optimally set, Kanban system outperforms CONWIP with a lower average WIP and the same level of throughput. That is, the distribution of kanbans can be an important design parameter of the system. We also propose two different policies to release cards in a CONWIP controlled assembly system, followed by their comparison results.     

CONWIP based control of a lamp assembly production line

Efficient and effective production control systems are very important for manufacturing plants. CONWIP, one of these production control systems, has a high potential of becoming the best one available because it suits a variety of production environments and is easy to implement. In the following paper, we compare the single-loop and multi-loop CONWIP production control systems for an actual lamp assembly production line producing different kinds of products with discrete distribution processing time and demand. A model is formulated with respect to total cost and service level. A novel rule-based genetic algorithm (GA) approach is proposed for the multi-loop CONWIP system to find the optimum parameter setting. The results have shown that the single-loop CONWIP production control system is more efficient than the multi-loop system. It can greatly decrease the total cost and the WIP (Work-In-Process) with zero shortage probability.     

Developing a framework for performance analysis of a production process controlled by Kanban and CONWIP

In this paper, we develop a framework for comparing pull production control systems, which defines and contains of activity interaction diagram and critical circuit. Kanban and CONWIP control systems are focused on and analyzed. We show that, for a production process controlled by Kanban or CONWIP, the critical circuit determines performance measures, such as the system throughput. Initial inventories as well as card distribution are important parameters that decide the critical circuit, and hence influence the system performance. In addition, by means of our proposed framework, we provide comparative results between Kanban and CONWIP control systems in tree-shaped production processes and serial production lines as sample applications of the framework. The results show that determining the certain superior production control system depends on the system parameters, such as the process structure, initial values and processing times.     

供应链存储系统无线射频识别使能的定量在制品法控制策略仿真

无线射频识别(radio frequency identification,RFID)技术的出现为库存控制策略的创新提供了一条有效的途径.本文利用RFID技术,将原有单个制造系统的流通卡系统推广到供应链的多级库存网络中,设计了RFID使能的电子流通卡系统.基于电子流通卡,实现了RFID使能的定量在制品法(constant work-in-process,CONWIP)控制策略;并建立了CONWIP控制策略的分销网络模型.为比较和验证CONWIP控制策略性能,开发了三级分销网络仿真系统,使用该系统,将其与RFID使能的(r,Q)策略进行比较,验证了CONWIP策略在一定条件下,能够有效降低存储成本、提高服务水平.     

多重入生产线的CONWIP投放方法研究

CONWIP（Constant Work in Process）是一种基于拉式（pull）控制物料投放的方法。最初应用于Flow Shop式生产系统,通过限制半成品数量以控制生产线运作提供可靠的制造周期。然而,原始的CONWIP方法不能适应半导体这类同一加工站多重人的生产系统。该文根据半导体生产线多重人的特性,提出与多重人瓶颈相结合的CONWIP投放方法,不仅控制生产线中的半成品数量,并且结合了TOC（Theory of Constraints）思想,从而提高生产线的性能。最后,通过一些仿真证明了方法的有效性。     

Optimization of a multi-Constant Work-in-Process semiconductor assembly and test factory based on performance evaluation

This paper considers a semiconductor assembly and test factory which is a three-segment-Constant Work-in-Process (CONWIP) system with overlapping machines. In the system, three types of carts circulate for meeting the physical requirements. The optimization problem in setting the suitable total Work-in-Process (WIP) level and the distribution in the three loops from the view of the trade-off between the throughput and the WIP level for the system is addressed. In the proposed model, the system is firstly modeled as a three-loop closed queue network and we propose an approximate method to evaluate the performance. The accuracy of the evaluation method was illustrated by numerical experiments, indicating that the method is fairly precise. Secondly, a Genetic Algorithm is designed to obtain near optimal results based on the performance evaluation. The semiconductor assembly and test system case as well as the application procedure were carried out in detail.     

FMS的CONWIP控制

生产存储控制是FMS设计的重要方面之一。CONWIP控制系统可以保证有效地使用昂贵的FMS设备的同时,使FMS满足顾客的需求,为此,对CONWIP控制下的FMS进行仿真,以分析不同处理时间对CONWIP控制下的FMS性能的影响。     

Development and evaluation of a Basestock-CONWIP pull production control strategy in balanced assembly systems

In this study, a new pull production control strategy called Basestock-Constant Work-in-Process (B-CONWIP) is proposed. It is used to control the flow of materials and information in balanced assembly production systems. This proposed control strategy uses one type of authorization cards called CONWIP card that limits the work-in-process (WIP) in the whole system. It has been applied in a single-product and a mixed-product assembly system balanced by two efficient Genetic algorithms introduced in literature. The performance of this control strategy is compared with another pull production control strategy called Basestock Kanban CONWIP (BK-CONWIP), which is a very promising production control strategy found in literature. The proposed strategy has two control parameters, CONWIP authorization cards and basestock levels while BK-CONWIP has three control parameters Kanban authorization cards, CONWIP authorization cards and basestock levels. The comparison is based on three performance measures average system WIP, percentage of satisfied customer demand (service level) and WIP variation between workstations. The performance of the proposed strategy B-CONWIP and BK-CONWIP is mainly similar in both types of assembly systems when mean demand rates are low with respect to mean service rates with the proposed strategy being easier to control and optimize. On the other hand, when mean demand rates are high with respect to mean service rates; B-CONWIP is preferable if service level is more important, while BK-CONWIP is preferable if WIP level is more important. Regarding WIP variation, it mainly depends on the efficiency of the balancing approach. The more efficient the balancing approach, the less WIP variation. Treating demand as lost instead of backordered results in decreased average system WIP and does not affect service levels in both PCSs. It is also shown that S-KDP is more flexible in dealing with situations of variable product mixes than d-KDP because control parameters can be used by any product which minimizes the effect of the unbalanced systems.     

A CONWIP model for FMS control

Production inventory control is one of the most important aspects of a flexible manufacturing system (FMS) design. CONstant Work In Process (CONWIP), which is a hybrid of push-and-pull type systems, offers an alternative to effective utilization of the expensive FMS equipment while still meeting customer requirements. In the selection of an FMS control method, material handling often becomes one of the capacity constraints which forms the basis of various research interests. In this paper, a structure-based model for a CONWIP-controlled FMS is proposed, and within it, the node type characteristics concept is used to describe the constraints in FMS. Furthermore, simulation is used to determine the card number based on the structure-based model. The simulation results demonstrate that the model is suitable for the design and operation of FMS. The model can be used as a manufacturing execution system of enterprise resources planning. An architecture for this integrated design based on Internet/Intranet systems is also proposed.