An integrated vendor-buyer cooperative inventory model for items with imperfect quality

This article develops a model to determine an optimal integrated vendor-buyer inventory policy for flawed items in a just-in-time (JIT) manufacturing environment. The aim is to minimize the total joint annual costs incurred by the vendor and the buyer. The proposed model extends the integrated vendor-buyer inventory model by accounting for imperfect quality items. The expected annual integrated total cost function is derived and an analytic solution procedure is proposed to determine the optimal policy. Finally, numerical examples are also given to illustrate the solution procedure presented in this article.     

Note on: An integrated vendor–buyer cooperative inventory model for items with imperfect quality

Huang [Huang, C., 2002. An integrated vendor–buyer cooperative inventory model for items with imperfect quality. Production Planning and Control, 13 (4), 355–361] proposes an integrated inventory model which allows a vendor and a buyer to minimise their expected integrated total cost function when the vendor's production process is not perfect. This note identifies two errors in the paper and provides a reformulation of the model.     

A discussion on economic ordering policy of deteriorated item for vendor and buyer

Yang and Wee (Economic ordering policy of deteriorated item for vendor and buyer: an integrated approach. Prod. Plan. & Cont., 2000, 11(5), 474–480) proposed an ordering policy for a vendor--buyer integrated model. This note examines the cost component of Yang and Wee's model and gives some insight on the derivation of the holding cost function. We have discovered that their model violates the positive holding cost characteristic and the total quantity-equality characteristic. A proposal to eradicate the problem is given.     

Economic ordering policy of deteriorated item for vendor and buyer: An integrated approach

This study develops an economic ordering policy of a deteriorating item with a constant production and demand rate. By considering the view of both the vendor and buyer, a mathematical model subject to single-vendor-single-buyer and multiple deliveries per order is developed. It can be shown that the integrated approach results in an impressive cost-reduction compared with an independent decision by the buyer.     

Implementation of JIT purchasing: An integrated approach

This article addresses the necessity of integration between buyer and supplier for effective implementation of the JIT system. An integrated lot-splitting model of facilitating multiple shipments in small lots is developed and compared with the existing approach in a simple JIT environment, single-buyer-single-supplier, under deterministic conditions for a single product. It is shown that the optimal policy adopted by the integrated approach can provide a strong and consistent cost-minimizing effect for both buyer and supplier over the existing approach.     

基于可控提前期的随机寄售库存模型

本文通过假定需求提前期为随机且可控的,将寄售库存（Consignment Stock,CS）模型拓展到随机情形。本文首先将库存成本分为与财务相关的成本和与储存相关的成本两部分,得出CS方式下买卖双方的联合期望总成本公式,然后将订货量、订货点、提前期、运送次数作为决策变量,求得系统的最优参数设置及最小总成本。文章最后提出一个算法,并通过仿真的形式表明无论在确定还是随机环境中,CS方式的总成本都可能优于集成化库存方式。     

A Generalized Framework for Quantity Discount Pricing Schedules

The use of price to influence a buyer's purchasing behavior and thus improve supply chain coordination has received considerable attention. The vendor and buyer are independent economic entities, each maximizing its own profit. We consider the case of a buyer with fixed annual demand, independent of cost. The vendor's objective is to set a price schedule that encourages the buyer to raise its order quantity, increasing the vendor's profits. We present a unified treatment of the problem, categorize different variations, and provide a common solution procedure for all cases.     

联合经济批量模型中的损失补贴与利益分配问题研究

针对单供应商和单采购商构成的供应链系统,分采购商占主导地位和供应商占主导地位两种情形,讨论了采购商的最优订货决策与供应商的最优生产决策,以及它们合作情形下的系统最优决策,给出了采购商和供应商各自独立决策与联合决策下,它们各自的成本函数以及供应链系统的总成本函数.最后,通过比较独立决策与联合决策下采购商和供应商的成本函数,分析了联合经济批量模型中的损失补贴与利益分配问题.     

A JOINT ECONOMIC-LOT-SIZE MODEL FOR PURCHASER AND VENDOR

In a typical purchasing situation, the issues of price, lot sizing, etc., usually are settled through negotiations between the purchaser and the vendor. Depending on the existing balance of power, the end result of such a bargaining process may be a near-optimal or optimal ordering policy for one of the parties (placing the other in a position of significant disadvantage) or, sometimes, inoptimal policies for both parties. This paper develops a joint economic-lot-size model for a special case where a vendor produces to order for a purchaser on a lot-for-lot basis under deterministic conditions. The focus of this model is the joint total relevant cost. It is shown that a jointly optimal ordering policy, together with an appropriate price adjustment, can be beneficial economically for both parties or, at the least, does not place either at a disadvantage.     

Vendor Selection with Bundling: A Comment*

In a recent article by Rosenthal, Zydiak, and Chaudhry (1995), a mixed integer linear programming model was introduced to solve the vendor selection problem for the case in which the vendor can sell items individually or as part of a bundle. Each vendor offered only one type of bundle, and the buyer could purchase at most one bundle per vendor. The model employed n(m+ 1) binary variables, where n is the number of vendors and m is the number of products they sell. The existing model can lead to a purchasing paradox: it may force the buyer to pay more to receive less. We suggest a reformulation of the same problem that (i) eliminates this paradox and reveals a more cost-effective purchasing strategy; (ii) uses only n integer variables and significantly reduces the computational workload; and (iii) permits the buyer to purchase more than one bundle per vendor.     

Lot‐sizing Decisions Under Limited‐time Price Reduction*

We consider the optimal lot‐sizing policy for an inventoried item when the vendor offers a limited‐time price reduction. We use the discounted cash flow (DCF) approach in our analysis, thereby eliminating the sources of approximation found in most of the earlier studies that use an average annual cost approach. We first characterize the optimal lot‐sizing policies and their properties, then develop an algorithm for determining the optimal lot sizes. We analytically demonstrate that the lot sizes derived using an average annual cost approach for the different variants of the problem are, in general, larger than the DCF optimum. While DCF analysis is more rigorous and yields precise lot sizes, we recognize that the associated mathematical models and the solution procedure are rather complex. Since simple and easy‐to‐understand policies have a strong practical appeal to decision makers, we propose a DCF version of a simple and easy‐to‐implement heuristic called the “Early Purchase” (EP) strategy and discuss its performance. We supplement our analytical developments with a detailed computational analysis and discuss the implications of our findings for decision making.     

有限时域与采购价格上升情形下的最优订货策略

研究了有限时域下采购商面对价格上升时的订货策略问题.在分析问题的基础上提出一种新的最优采购策略,并分析了价格上升幅度对订货量的影响,以经典EOQ模型的总成本为基准,比较了本文提出的策略与文献已有策略在成本节约上的差异.本文对库存总成本的计算方法更加精确;分析表明在有限时域背景下采购商的临时订货量决定于价格上涨的幅度、在库库存以及时段长度.     

允许延期支付条件下退化性商品的销售与定购策略

针对退化性商品,允许延期支付的条件下,分别从供应商和零售商的角度出发,利用斯坦博格博弈模型给出了其如何制定最优的销售和定购策略,以实现其利润的最大化。通过算例给出了这一问题的求解算法,并且分析了利率对于信用交易期限、供应商利润、零售商利润、销售价格、订购周期及订货批量的影响。为供应商信用交易策略和零售商库存决策的制定提供依据。     

Should You Buy Your Customer's Values? On the Transfer of Moral Values in Industrial Purchasing

This article discusses a transfer of moral values between purchasing and supplying organisation in the manufacturing sector. In the first part, the relevant literature is discussed to glean criteria, which could facilitate such a transfer. Given a scarcity of research into ethics in purchasing, the literature review is extended into related fields, such as total quality management, environmental purchasing in retailing and minority vendor programmes in the U.S. In the second part, the question is raised whether such a transfer can at all lay claim to being of moral value. The process is screened against established ethical theories, which are found to support it. Finally, the financial impact of such a policy on the supplier is considered. This revised version was published online in July 2006 with corrections to the Cover Date.     

两级供应链产品质量控制契约模型分析

基于博弈论和委托代理理论,研究在两级供应链中如何进行质量控制契约设计的问题。建立生产商和购买商的期望收益函数模型,生产商对其生产过程投资水平进行决策并确定其产品质量预防水平;购买商进行质量评价决策并确定其产品质量检验水平。生产商存在降低其生产过程投资水平的道德风险问题,在生产过程中将"削减投资",购买商为激励生产商提高其生产过程投资水平将支付"信息租金"的成本。购买商在进行产品质量检验决策时,存在夸大产品质量缺陷率的道德风险问题,在产品质量检验过程中将"过度检验"。运用最优化原理,求解生产商的最优生产过程投资水平、产品质量预防水平和价格折扣额与购买商的最优质量检验水平和外部损失分摊比例,并进行了算例分析,结果表明:当生产商提高其生产过程投资水平时,其质量预防水平将显著增加,购买商的质量检验水平将显著下降;随着购买商质量检验水平的提高,生产商所提供的价格折扣额先增大后减少,生产商所承担的外部损失分摊比例将会下降,其期望收益增加,购买商的期望收益将会减少,供应链联合期望收益将呈现"倒U"型,求解了期望收益的最大值及各契约参数的值,结果证明所提出的质量控制契约模型是可行的。     

Storage constrained vendor managed inventory models with unequal shipment frequencies

We consider a supply chain where a vendor manages its multiple retailers' stocks under a vendor managed inventory (VMI) contract that specifies upper stock limits at the retailers' premises and overstock costs for exceeding those limits. We formulate a mixed integer nonlinear program that minimizes total supply chain costs and allows unequal shipment frequencies to the retailers. We develop an algorithm to solve its relaxed version which provides a lower bound cost solution. We propose a cost efficient heuristic procedure to generate delivery schedules to the retailers. We conduct a sensitivity analysis to provide insights on the performance of the proposed heuristic. Results show that our heuristic finds optimal or near optimal solutions, and it proposes substantial savings compared to the total supply-chain cost in the cases where there is no VMI and where there is VMI but with equal shipment frequencies to retailers.     

Congressional committee hearings

Committees are the instruments through which Congress chooses to screen and process proposals to change public policy. A committee decision to hold hearings, except for the annual appropriations and budget process, indicates a matter has crossed the threshold of political salience. These proceedings serve to focus public and political attention and may be a prelude or an alternative to legislation. This article explores the multipurpose nature of hearings, examines their structure and procedure, and discusses their contents. The aim is to offer a framework within which to analyze and assess the printed product.     

Optimal Quantity Discount Design with Limited Information Sharing*

In this article we address the optimal quantity discount design problem of a supplier in a two‐stage supply chain where the supplier and the buyer share annual demand information only. The supply chain faces a constant deterministic demand that is not price sensitive and operates with fixed setup costs in both stages. We show that the supplier can actually moderate a cost‐minimizing buyer to order in quantities different than the buyer's optimal order quantity in the traditional setting and develop a multi‐breakpoint quantity discount scheme that maximizes supplier's expected net savings. The proposed multi‐breakpoint discount scheme can be easily computed from the available information and, while also maximizing the supplier's net savings, is very effective in achieving high levels of supply chain coordination efficiency in the presence of limited information.     

Standard Container Size Discounts and the Single-Period Inventory Problem*

This paper analyzes the problem of choosing the optimal order quantity and its associated number of standard containers making up the order for single-period inventory models under standard container size discounts. A range is determined that contains the optimal order quantity. Two algorithms are presented. The first algorithm solves the general case in which there is no restriction on the types of containers included in an order. The second algorithm solves a more restricted policy that requires the buyer to accept the order with successively smaller container sizes.     

Capability,Quality, and Performance of Offshore IS Vendors: A Theoretical Framework and Empirical Investigation

Information systems (IS) offshoring has become a widespread practice and a strategic sourcing choice for many firms. While much has been written by researchers about the factors that lead to successful offshoring arrangements from the client's viewpoint, the vendor's perspective has been largely scarce. The vendor perspective is equally important as offshore IS vendors need to make important decisions in terms of delivering operational and strategic performance and aligning their resources and processes in order to meet or exceed targeted outcomes. In this article, we propose and test a three‐level capability–quality–performance (CQP) theoretical framework to understand vendor outcomes and their antecedents. The first level of the framework represents three vendor capabilities: relationship management, contract management, and information technology management. The second level has three mediating variables representing process quality: partnership, service, and deliverable quality. The third level has three dependent variables representing vendor outcomes: operational performance, strategic performance, and satisfaction. The model was tested with 188 vendor firms from India and China, the two most popular destinations for IS offshoring. Results support the CQP framework; vendor capabilities are significant predictors of intermediate quality measures, which in turn affect vendor outcomes. Implications of the study findings to both theory development and IS offshore vendor strategic decision making are discussed.