基于缩短多阶响应周期的Push/Pull结合的库存管理体系

在顾客化大量生产的环境下，响应速度是企业竞争力的关键，论文从缩短供应链多阶响应周期对库存管理产生的问题出发，建立Push/Pull结合的库存管理体系，阐述了其基本运行机制，并对运行机制中准时制(JIT)与快速响应(QR)结合、供应链延迟点等问题进行了分析，并建立数学模型对库存与响应周期之间的关系进行了研究。     

多级库存 RFID使能的 Push／Pull与（s，S）策略的仿真对比

基于RFID使能的电子看板以供应链分销网络三级库存系统为例,根据其结构特点和运作时各阶段节点企业的功能,借鉴单工厂多阶段生产存储系统最优的Push／Pull混合控制结构,设计了制造商库存采用Push控制,分销商和零售商库存采用RFID使能的Pull控制的RFID使能的Push／Pull混合控制结构。为验证混合控制策略的性能,将其与基于RFID技术的（ s,S）策略相对比,建立了两策略的数学模型及性能评价指标。考虑到供应链系统的动态性与随机性,基于离散事件系统仿真原理,设计并实现了系统的仿真模型,通过仿真实例验证并分析了混合控制策略的有效性和优越性,为供应链多级库存网络管理实践提供了参考。     

基于时间竞争的MRPⅡ、JIT与TOC集成化生产计划与控制模型

构建了基于TOC的以MRPⅡ生产计划系统为主导的“Push”体系和以JIT生产控制系统为主导的“Pull”体系相结合的集成化生产计划与控制模型。该模型以追求瓶颈资源能力的最大利用为出发点,根据市场需求预测和JIT生产拉动进行生产计划的动态优化调整,同时利用采购计划和供应商能力计划及看板系统对生产过程实施双重控制。     

基于时间竞争的MRPⅡ、JIT与TOC 集成化生产管理模式

从MRPⅡ、JIT与TOC的基本思想出发，提出了三者集成的基本思路，构建了基于TOC的以MRPⅡ生产计划系统为主导的“Push”体系和以JIT生产控制系统为主导的“Pull”体系相结合的集成化生产计划与控制模型。该模型以追求瓶颈资源能力的最大利用为出发点，根据市场需求预测和JIT生产拉动进行生产计划的动态优化调整，同时利用采购计划和供应商能力计划及看板系统对生产过程实施双重控制。     

浅谈水晶报表的应用

通过．NET平台的Crystal Reports（水晶报表）,建立报表实现Pull和Push两种模式连接后台Oracle数据库。实现自由设计报表、生成报表,生成图表等报表功能。     

超临界水/正丁醇混合流体对CF/EP复合材料的降解作用

采用水/正丁醇混合流体降解碳纤维/环氧树脂(CF/EP)复合材料以回收高性能CF,分析了水、正丁醇和水/正丁醇混合流体对EP基体的降解能力,研究了水/正丁醇的体积比例、温度、时间及KOH浓度等对EP基体的降解率影响。结果表明:混合流体对EP基体的降解能力优于水和正丁醇;临界条件下,水的含量越高,混合流体对EP基体的降解能力越强;EP基体的降解率与温度、时间及KOH浓度呈正相关性;350℃、30min条件下,采用水含量为50%的水/正丁醇混合流体作为反应溶剂时,EP基体的降解率达到93.4%,与纯组分的水和正丁醇相比,CF/EP复合材料的降解率分别提高10.9%和24.6%;与原碳纤维相比,混合流体回收的CF单丝拉伸强度保持率在97%以上,且韦氏模数相近。     

G/G/S系统队长的优化控制

制造系统生产流水线由于受随机干扰的影响,经常出现待加工工件积压或短缺的现象.针对这种情况,给出G/G/S系统队长控制图的优化设计方法.该方法对给定的第一类风险,结合工件短缺的惩罚费用和积压的存贮费用,提出合理度量控制图损失的损失函数及控制限确定方法.通过与已有方法的比较分析,证明该方法是有效、可行的.     

程序设计中混合使用VC/VB编程的研究探析

随着科学技术不断的发展,程序设计变得越来越重要,而程序研究也变得越来越重要。原有单个编程数据结构表达相对困难,再加上处理周期难等特点,无法保证程序设计有序进行。而使用混合编程,尤其使用VC/VB混合编程不仅能有效提高程序执行效率,同时也能使程序编制更具灵活性。为使VC/VB混合编程更好满足程序设计需求,应该对VC/VB混合编程相关内容进行分析。主要从混合编程混合编程概念及VC/VB混合编程特点、VC/VB混合编程方法、VC/VB混合编程使用时应该注意的问题等方面出发,对程序设计中混合使用VC/VB编程进行相应分析。     

R125/R290及R125/R600a热泵工质适用温区探究

循环温升保持45℃,热源进口温度范围为10—45℃的热泵工况下,建立了基于控制换热器窄点温差的热泵循环模型,对小温度滑移混合工质R125/R290(质量配比25/75)及大温度滑移工质R125/R600a(质量配比10/90)的热泵循环性能分别进行了分析研究。发现R125/R290制热循环性能系数COPh随名义蒸发温度的升高而提高,而对于R125/R600a,COPh却变化平缓。同时两种混合工质的排气温度和冷凝压力均在系统安全运行范围之内。结果表明:对于小温度滑移工质R125/R290更适合于低温热源工况,大温度滑移工质R125/R600a则更适用于高温热源工况。     

基于区域极点配置的汽车主动悬架H_2/H_∞控制

利用混合H2/H∞控制方法设计了某重载车辆悬架控制器。以此种方法设计出的控制器,通过H∞控制指标保证被控对象约束输出传递函数的无穷范数低于适当γ值的同时,最小化一个给定的H2性能指标函数,较好的解决了悬架系统性能和系统鲁棒性之间的折衷优化控制问题,同时,通过将闭环极点配置在指定位置,保证了系统的动态性能,结果显示,通过将单一范数(H2或H∞)控制方法改进为混合范数H2/H∞控制方法,强化了每种范数各自的优势,系统综合性能品质得到了保证。     

拉动系统在组装工厂的实施

看板、供料方式、物料超市等基本要素组成了拉动制造系统,这些基本要素的设定方法决定了拉动制造系统特点,这些特点反过来也制约着拉动系统的实施。通过顺序拉动等多种方法的提高,可以有效地克服这些特点,在一般拉动系统的基础上,进一步减小库存,提高效率。     

高炉拉杆的断裂分析及防断方法

本文利用断裂力学方法，对引起重大事故的断裂拉杆断口进行分析，从而确定造成拉杆断裂的原因及断裂特性，同时提出了相关的解决措施，     

Sensitivity of 'Push' and 'Pull' strategies to information updating rate

One would expect a continuous production planning and control system to be more sensitive to information inaccuracy than a periodic one. In practice, a major source of information inaccuracy is the updating rate of the perceived system state. This phenomenon is particularly significant in global firms that must employ appropriate technology and procedures for updating the corporate information throughout its branches. The study compares 'Push' and 'Pull' strategies for production planning and control under different updating rates for inventory information. For this purpose, we propose a Pull control mechanism for an environment characterized by inaccurate information. Then we construct a simulation model for a specific flow-shop production process that can be controlled by either the Pull or Push approach. The simulation results show a significant domination of the Pull strategy over Push. The results confirm that the Pull approach protects the flow of materials against machine and market variations, which were known, and also against a lack of information, which is new. The Pull strategy is less sensitive to the information updating rate since it smoothes the materials' flow and thus the inventory information gaps (known versus actual) are much smaller.     

CONWIP implementation in a system with cross-trained teams

Although a significant amount of research exists on the implementation of the CONstant Work In Process (CONWIP) production control strategy in different types of manufacturing environments, the challenge posed by the complex flow of multiple products through the case manufacturing system of this work necessitates defining a unique type of item release rule to operate with the CONWIP control. The case system is a chair cover production line, which has sets of cross-trained teams that can process its different product models with different levels of efficiency. This work focusses on the CONWIP control strategy, but with the introduction of a new item release rule for prioritising items for release into the system. Results from simulation experiments show that operating CONWIP with an item release rule that is synchronised with the work rate of each of the system's cross-trained teams improves its performance. In comparison with a First in First out (FIFO) rule, this item release rule shortens the system throughput time. It also increases the chances of items being processed by the team most suitable for them, thereby minimising the quality and efficiency issues that might occur in systems that consist of teams with varying levels of proficiency for processing the different product models. Irrespective of the item release rule that is applied, CONWIP achieves a better distribution of workload amongst the teams than a Push control achieves.     

Workload balancing capability of pull systems in MTO production

Pull systems focusing on throughput time control and applicable in situations with high variety and customisation are scarce. This paper compares three unit-based pull systems that can cope with such situations: POLCA, CONWIP and m-CONWIP. These systems control the shop floor throughput time of orders by limiting the number of orders on the shop floor. However, their effectiveness in terms of reducing total throughput time is questioned. Theory states that an improvement in the average total throughput time will be due to the workload balancing capability of a pull system, but that many pull systems lack this capability. This paper shows that this workload balancing capability exists for POLCA and m-CONWIP, but not for CONWIP. The magnitude of the effect differs strongly, depending on the configuration of the system, the order arrival pattern and the variability of the processing time of the orders.     

A simulation study of CONWIP assembly with multi-loop in mass production,multi-products and low volume and OKP environments

This paper studies the performance of constant work-in-process (CONWIP) assembly system with multi-loop in mass production, multi-products and low volume and one-of-a-kind production (OKP) environments using simulation. We propose five basic design patterns of CONWIP loop and develop eight control policies of CONWIP loop based on the design pattern for standard assembly system. The performance of developed loop policies is evaluated in three production environments. In particular, control policies of CONWIP loop in OKP environment provide a valuable reference for OKP shop floor controlling. A heuristic algorithm of searching work-in-process (WIP) upper bound, the deadlock phenomenon in CONWIP assembly system and suggestion are introduced specifically. The summary of CONWIP installation guidelines in the mixed assembly system can apply CONWIP theory to practise.     

Analysis of production control systems kanban and CONWIP

In this paper we describe and classify different pull production systems. The production control systems kanban and CONWIP are then analysed with respect to production rate and average W1P. We examine single product flow lines with exponential service time distributions and unlimited demand at the final buffer (saturated lines). We show that the distribution of cards (kanbans) has a significant effect on the performance of kanban systems. Different types of kanban control mechanisms show equivalent performance data, if the distribution pattern is adapted accordingly. Our research shows that the kanban system is more flexible with respect to a given objective than the CONWIP system, because in addition to the total card number the card distribution is a control parameter. Moreover for a given production rate the average WIP is lower in a kanban system than in a CONWIP system. We identify the average WIP in the interstage buffers as important parameter and describe the ‘WIP bowl phenomenon’ as result of optimum card distributions. Concluding remarks and directions for future research conclude the paper.     

CONWIP拉式机制在自动包装线中的应用设计

提出了一个具有固定在制品拉式机制(CONWIP)的自动包装线控制方案。讨论了自动包装线实现这种拉式机制所面临的问题,给出了采用PLC、传感器和工业组态技术的实施方法。通过某企业自动包装线实际应用,验证了这种方案的可行和高效。     

Service-level performance of MRP,kanban, CONWIP and DBR due to parameter stability and environmental robustness

Decisions regarding production planning and control strategy (PPCS) choices can be classified as strategic, whereas parametrization issues are of a tactical nature. However, readjustment is often skipped either as a result of a lack of planning expertise or because it would require extended planning. For this reason, robustness, which is defined as PPCS behaviour within dynamic environments, is investigated. To achieve a greater understanding of the sensitivity on parameter changes in a production system, PPCS stability is examined. An eM-Plant based simulation model is presented that discusses the service-level performance of material requirement planning (MRP), kanban, constant work in process (CONWIP) and drum–buffer–rope (DBR) in a flow-shop with attention to the work in process (WIP). Although the service-level performance of CONWIP exceeds that of the other systems, CONWIP struggles to maintain its advantage under dynamic conditions. The paper seeks to support industrial practitioneers both in their choice of a specific PPCS and to parametrize the PPCS successfully.     

Lot-splitting approach of a hybrid manufacturing system under CONWIP production control: a mathematical model

This paper discusses the advantages of lot splitting in hybrid manufacturing environments where cellular and functional layouts are combined under Constant Work in Process (CONWIP) production control. The proposed model fills a research gap in the related literature by applying lot splitting and pull production simultaneously. A linear CONWIP control mathematical model that minimises the average flow time is developed in case of lot splitting. The developed model has sequence-dependent set-up times. The demand level, coefficient of variation (CV) impact and set-up time reduction effect on CONWIP production control are also investigated. The model is solved using GAMS21.6 optimisation software; the optimal backlog list, the number and size of sublots are reported. The proposed model is compared with lot production under push control in different settings as well as with two different heuristics from the literature. Experimental results indicate that in all settings, the lot splitting is more advantageous than lot production in terms of average flow time. CV has a greater effect than set-up time reduction on average flow time.