考虑损失规避与促销行为的VMI供应链协调契约模型

针对供应商管理库存(VMI)模式下考虑损失规避型供应商与零售商促销行为的二级供应链协调问题,分别分析了分散VMI供应链情形下损失规避型供应商与零售商的最优策略和集中VMI供应链情形下供应链的最优策略,并构建了批发价格-促销成本分担契约下的VMI供应链协调契约模型,并且证明了该供应链协调契约模型的有效性。通过博弈分析得到的结论是:零售商的促销努力水平的提高能够促使损失规避型供应商增加其产品生产量,而损失规避型供应商的产品生产量的增加会促使零售商提高其促销努力水平以便保持市场竞争优势;批发价格契约不能协调此二级VMI供应链;一定条件下批发价格-促销成本分担契约能够协调此二级VMI供应链。     

双侧公差限产品的合格概率计算方法

为了定量分析产品的合格性,在正态分布假设前提下,考虑参数测量结果测量不确定度的影响,建立了双侧公差限产品的合格概率计算模型,为批量产品和单件产品合格概率的定量计算提供了理论依据,同时给出了测量分析计算实例。结果表明:产品合格概率的定量计算结果,对于分析产品质量问题成因和提高产品质量具有重要的指导意义,给出的方法对单侧公差限设计要求的产品合格概率的计算同样具有参考价值。     

双因素视角下复杂产品供应链质量激励契约研究

考虑短期经济收益和长期质量声誉的综合影响,设计了一类复杂产品供应链质量激励契约,辅助主制造商诱导供应商在实现自身最优收益的同时,自发地提升外协系统的质量水平,实现质量合作主体综合效用的共赢。针对复杂产品外协系统小批量订购模式,从广义质量损失视角测度外协系统质量水平,构建供应链质量合作主体的"收益-声誉"效用函数。考虑供应商质量信息优势,构建"委托-代理"模型分析固定支付情形下复杂产品供应链质量合作的均衡解。探寻质量激励函数对合作主体综合效用的激励作用,以合作方最优质量水平离差最小为优化目标,考虑实际效用提升、有效激励和主动参与等多种约束条件,构建目标规划模型分析质量激励情形下供应链质量合作的均衡解及改进效果。针对某商用飞机公司和某航空发动机公司的质量合作开展案例研究,通过比较分析验证质量激励函数的合理性和有效性,为复杂产品供应链质量激励契约设计提供了一种新的分析思路。     

复杂产品供应链质量改进成本分担契约研究

考虑短期经济收益和长期质量声誉对合作效用的综合影响,设计一类复杂产品供应链质量改进成本分担契约,辅助主制造商诱导拥有私人质量信息的供应商自发提升外协系统质量水平,消除隐匿质量信息的不良影响,在保障供应链收益的同时实现合作主体综合效用共赢。针对复杂产品外协系统小批量研制、接受质量全检的特性,结合广义质量损失测度外协系统质量水平,考虑质量特性权重表征质量声誉,进而构建供应链质量合作主体的"收益-声誉"效用函数。考虑供应商私人质量信息优势,构建委托-代理模型分析固定支付情形下质量合作实现的均衡条件。探寻质量改进成本分担契约的作用机理,以合作主体最优效用下质量水平离差最小为优化目标,构建目标规划模型分析质量合作的均衡解及质量改进效果。针对某商用飞机公司和某航空发动机公司间的质量合作进行案例研究,验证质量改进成本分担契约的可行性及有效性,为复杂产品供应链质量合作质量激励契约设计提供了一种新的分析思路。     

装配和制造综合的公差分配优化设计

面对航天产品的公差分配不合理的问题,提出综合考虑装配和制造两层面的公差分配方案。分析研究对象装配尺寸链的组成环情况,在零件制造的工序级别以制造成本-公差函数和质量损失函数为优化目标,以装配公差要求、工序间加工余量和工序的加工能力为约束条件,建立公差分配的多目标优化模型。采用基于Pareto机制的带精英策略的非支配排序遗传算法求解公差分配优化模型。以某航天企业电液伺服阀产品中衔铁组件的制造和装配为例,验证了模型的适用性和有效性。     

微结构特征对微结构零件注射成型流场均匀性的影响

在Navier-Stokes方程基础上,配合适当边界条件,借助计算流体力学软件CFD-ACE实现了单侧分布矩形微结构、梯形微结构和双侧分布矩形微结构零件模型的流场仿真,得到了三种零件的速度场和剪切速率场.结果表明,单侧矩形微结构零件各微结构截面的速度和剪切速率都有较大差异;单侧梯形微结构零件各微结构截面的剪切速率分布一致,速度分布不一致;双侧矩形微结构零件三个微结构截面的速度和剪切速率都一致.单侧分布梯形微结构零件流场均匀性好于单侧分布矩形微结构零件流场均匀性,双侧分布的微结构零件流场均匀性好于单侧布置的微结构零件流场均匀性.     

非对称损失函数的质量特性值优化选择

质量特性目标值的选定是一个重要的命题,它是影响质量成本的一个重要因素.由顾客定义的特性目标值并不一定能使得总体的质量损失最小化.针对此问题,讨论了非对称的质量损失函数,在此基础上构造出质量特性目标值的优选模型,得到最优目标值.在模型的应用中表明:质量损失系数不变、质量特性左偏比右偏更有害的情况下,质量特性最优值与期望总损失随分布标准差的增大而增大;分布标准差不变的情况下,质量特性最优值与期望总损失相对质量损失系数具有一定的稳健性.     

一种多阶段供应商选择的混合整数规划模型

在建立供应链合作伙伴关系中,供应商的选择是供应链管理的一项重要内容.在现有文献的基础上对供应商的选择模型进行了改进,建立了集成单阶段与多阶段供应商选择的混合整数规划模型:既可以选择单阶段供应商,也可选择多阶段供应商即供应商的供应商的供应商等等.在模型中考虑了每个潜在供应商的能力约束,以供应商在产品价格、质量、配送水平等三个方面引起总的客户不满意度最小化作为选优的依据.     

基于模拟试验法的离散公差稳健设计

 在分析计算机辅助公差设计技术的研究现状的基础上，提出了基于模拟试验法的离散公差稳健设计方法．在该方法中将加工成本与质量损失作为两个独立的目标函数，从而建立离散公差优化设计模型，采用试验设计法和CP方法相结合的技术实现公差的稳健设计，最后用实例证明该方法的可行性．     

基于随机灰靶模型的多质量特性产品参数选择北大核心CSSCI

针对传统田口质量损失函数的一些不足,提出一组改进型田口质量损失函数,并给出了质量特性取值"中靶"和"脱靶"的范围,为文中剔除"脱靶"对策、确定满意区域提供依据;以损失期望作为灰靶模型效果测度的基本工具,在此基础上,提出一系列灰靶效果测度方法;以正交试验设计为基础,针对多质量特性产品参数选择的具体问题,考虑噪声因素的概率分布,构建了基于改进型田口质量损失函数的多质量特性产品参数设计随机灰靶模型,并给出最优对策的判断标准。案例研究表明该模型可以确定相对最优参数水平组合,解决多质量特性产品参数选择问题,该方法新颖清晰、易于操作,可辅助工程设计者进行决策。     

Mathematical modelling of test limits and guardbands

To gain market share on product performance, suppliers will routinely specify product datasheet (DS) performance to tighter than six sigma specifications. To maintain quality levels in this instance, the product must be 100% tested in production to screen out parts that are outside specification. Because of test measurement error and temperature drift, the test limits (TLs) used must be guardbanded tighter than the DS limit to ensure that the shipped product meets the parts per million requirement. These guardbands are protection zones that protect the customer from receiving parts that are outside specification. A review of current guardbanding techniques finds that they are conservative in nature. New guardbanding models are presented, which calculate the limit sets required for production test, quality assurance test and DS limit specifications. These models account for both test measurement error and temperature drift. Model results show that the guardband required varies with Cpk of the TL, test measurement error and temperature correlation coefficient. Copyright © 2009 John Wiley & Sons, Ltd.     

Economic design of the specification region for multiple quality characteristics

Economic specification limits have typically been developed on the basis of a single quality characteristic. From the viewpoint of the customer, products are often evaluated based on multiple quality characteristics. The specification region for multiple quality characteristics must be determined on an economic basis where we minimize the total loss to both the producer and the customer and thus to the whole society. In this paper a multivariate normal distribution is considered for the quality characteristics. The specification region is given by truncating the multivariate normal distribution. We present the optimization model to develop the specification region for multiple quality characteristics based on the framework of multivariate quality loss function.     

Economic tolerance design for quality

This paper provides a few general mathematical models for determining product tolerances which minimize the combined manufacturing costs and quality loss. The models contain quality cost with a quadratic loss function and represent manufacturing costs with geometrical decay functions. The models are also formulated with multiple variables which represent the set of characteristics in a part. Applications of these models include minimizing the total cost with effective tolerance allocation in product design.     

A cubic quality loss function and its applications

The traditional quality evaluation method believed that when the product quality characteristic was within the specification limit, no loss was produced. Taguchi proposed that even if the characteristic was within the range of users' demand, the fluctuation of quality characteristic would still cause loss to users and society. Therefore, he proposed a quadratic quality loss function to describe this loss. The function was established based on the Taylor expansion. It neglected terms with powers higher than 2, which would cause a certain deviation between the calculated and true value. Moreover, the tolerance and loss in the quadratic loss function must satisfied specific relationship, which limited its use. In this paper, the Taylor expansion items are raised to third order. The quality loss coefficients are discussed and analyzed so that the cubic quality loss function is established. In addition, the method of calculating hidden quality cost is given by using the cubic loss function. The hidden quality cost is affected by the quality loss coefficients and should be a range. The cubic quality loss function studies the inapplicability of quadratic loss function, so it widens the scope of application of quality loss function.     

Optimal process mean and quality improvement in a supply chain model with two-part trade credit based on Taguchi loss function

The two-part trade credit policy is developed to accelerate cash inflow that can avoid bad debt risk in the earlier economic order quantity (EOQ) models allowing only one period of time for delay in payment. Taguchi loss function has proved to be a more realistic function for fitting the actual quality loss cost in economic product quantity (EPQ) model. To minimise quality loss, optimal process mean setting shifts process mean to balance the cost outside the specification limits, quality improvement applies investment to reduce process variation. Supply chain integration has been proved that it can be used to minimise the entire cost more effectively than independent EOQ or EPQ models. This paper improves the earlier studies by incorporating the above research topics that have not been simultaneously discussed before, develops a supply chain model based on the Taguchi loss function, which combines the trade strategy from the retailer’s perspective and the quality adjustments from the supplier’s perspective to maximise total supply chain profit. We find that the trade credit terms definitely affect suppliers and retailers’ optimal decisions, and numerical examples can provide decision references for supply chain managers to set a trade credit policy and control quality.     

The development of a robust design methodology for time‐oriented dynamic quality characteristics with a target profile

Innovative engineering techniques are often sought within the manufacturing environment to improve product quality and promote more cost‐effective strategies. Robust design methods are frequently used to serve this purpose, with the objective of minimizing the variability inherent within a particular process or system. A review of the literature suggests that most robust design research involves the study of static quality characteristics, given a pre‐defined specification interval or region and target value. In addition to proposing a methodology for working with dynamic quality characteristics where the specifications and target value may change over time, this paper offers two other distinct contributions. First, those researchers who have examined dynamic systems traditionally consider the effects of a signal factor on a response variable on the identification of optimal factor settings. In contrast, this paper will consider the effects of a quality characteristic changing over time, thus removing the need to confine the problem to signal–response systems. Furthermore, most researchers consider the optimization of the process mean according to the costs of non‐conforming to an established specification interval or region. This paper, however, utilizes a methodology involving the simultaneous optimization of the process mean and variance while expanding the problem to consider a loss in quality attributed to deviation from a target value over time. Copyright © 2010 John Wiley & Sons, Ltd.     

Capability Indices and Conformance to Specification: The Motivation for Using Cpm

Proposed is a perspective on quality that is different from but consistent with the current Six Sigma thinking. The focus is still squarely on the customer, but the concept of a “defect” is reevaluated. This new perspective can be used to help define key characteristics, process capability, and evaluate overall product quality using a loss function. This article focuses on the concept of process capability using this perspective. Central to the proposed quality perspective is ability to meet the customer's product specifications rather than ability to meet the component feature specifications. Current product and component quality metrics can drive the wrong decisions and wrong behaviors. This can add significant cost to internal processes and suppliers, and inadequately protect the customers from defective products. The new perspective defines component and process quality based on the probability of meeting the product specifications rather than the individual component feature specifications. Cpm is a simple process capability metric that can indicate the probability of meeting the customer's product specification. Cpm can be used to better estimate the cost of poor quality than can be estimated by using Cpk, and thus can be used to better manage product quality to the customer.     

Incorporation of high recyclability material selection in computer aided design

Manufacturing are now under increasing pressure of tighten environmental legislation to preserve natural resources. Product design, as a part of manufacturing activities, has to be more concern to deliver product specification with reduced environmental impact. Design for Recycling (DFR) is one of the promising approaches in prolonging material utilization of a product in the early stage of design. DFR focus on harmonizing product design with the recycling practices in order to minimize the loss of valuable materials and preventing unnecessary waste streams at the end of product’s life. In turn, it limits the usage of natural resources.To implement DFR, designers are faced with the challenge of compromising different design objectives such as cost, functional or technical requirements and product’s recyclability performance. This paper attempts to propose an intelligent approach that could facilitate designers to make an easy and quick recyclability assessment as well as selecting recyclable materials integrated with computer aided design. In this paper, the use of fuzzy inference system and genetic algorithm is proposed to optimize the multi-objective problem in the selection of recyclable materials. Case study on the actual conceptual design using computer aided design environment is demonstrated and showing that the proposed method successfully can be applied concurrently during product design. Comparison of proposed method with Sustainability Express Solid Work is also presented. The proposed method can assist product designers to design a high recyclability product without ignoring technical perspectives.     

Optimal tolerance design for product life cycle

This paper provides mathematical models to determine optimal tolerances for which the combined manufacturing costs, quality loss, and scrap/rework costs are minimized. The models include cases such as a single component, as well as multiple components for a product. The models also consider the constraints such as design functionality restrictions, product quality requirements, and process capability limits. The models are mainly developed for application in both engineering management and engineering design.