Joint decision of procurement lot-size,supplier selection,and carrier selection

The joint decision making of procurement lot-size, supplier selection, and carrier selection has potential to reduce buyer's purchasing expenditures. Furthermore, the total logistics cost can also come down through economies of scale in the purchasing and transportation costs, and reduction in supply chain disruptions such as rejections and late deliveries. We study a procurement setting in which a buyer needs to purchase a single product from a set of suppliers over finite discrete time periods to satisfy service level requirements. The suppliers offer all-unit quantity discounts, and transportation cost depends on carrier capacity as well as geographical location of suppliers. This paper proposes an integer linear programming model to simultaneously determine the timings of procurement, lot-sizes, suppliers and carriers to be chosen so as to incur the least total cost over the planning horizon. A numerical example is included to demonstrate the effectiveness of the proposed model in establishing tradeoffs among purchasing cost, transaction cost, and inventory holding cost. Sensitivity analysis has been carried out to understand the effects of the model parameters on the purchasing decisions and total cost. Managerial insights of this study serve as a reference for decision makers to develop effective procurement strategies.     

Sourcing Decisions with Capacity Reservations under Supply Disruptions

Firms employing both offshore outsourcing and nearshore sourcing strategies may face supply disruption, demand uncertainty, and quality risks simultaneously. Sourcing decisions become inevitably important and complicated when both profit and the customer-service level are taken into consideration. In this paper, we model a scenario where a manufacturer who faces stochastic demand procures major modules from an overseas supplier and two local suppliers. The overseas supplier offers quality products while being susceptible to disruption risks; if the local suppliers, who are completely reliable and serve as a backup, offer products that are of inferior quality, it may result in lower market acceptance and a bad experience for the final customers. The manufacturer has to reserve capacity with backup suppliers before urgent orders are placed, when the primary source experiences a shortfall. We explicitly derive the manufacturer’s optimal order quantities and reservation quantities, which are functions of the heterogeneous suppliers’ wholesale prices, reservation prices, and other parameters. The impacts of the fill-rate constraint and customer-experience quality constraint on the manufacturer’s purchasing decisions are investigated. Interesting managerial insights on the merits of backup sourcing with capacity reservations for managing demand uncertainties and supply disruption risks are also discussed.     

市场需求变化条件下短生命周期产品的订货策略

在短生命周期产品供应链的管理中有一个突出问题，即制造商如何制订有效的订货条件以及零售商如何利用这些订货条件进行合理订货.在市场需求变化条件下，短生命周期的产品订货分为两个阶段：第一阶段初从供应商那里订货一次．第一阶段末第二阶段初，根据市场需求变化再订货一次：本文研究了在一个产品生命周期中，在市场需求变化下，零售商和供应商如何制定有利于双方的第二次订货时间，以及考虑库存成本的零售商在两次订货中怎样采用最优的策略.     

Optimal structure of joint inventory-pricing management with dual suppliers and different lead times

We consider a joint inventory-pricing control problem in a single-product, periodic-review, dual-supplier inventory system. The two suppliers have different lead times. One expedited supplier offers instantaneous replenishment, and one regular supplier requires an L-period lead time for delivery. The supply quantity is stochastic and the demand is price-dependent. For the expedited inventory replenishment, we characterize the optimal policy as a state-dependent almost-threshold policy by extending the stochastically linear in mid-point to a multidimensional setting. To investigate the optimal regular inventory replenishment and pricing policy, we propose the notions of partially stochastic translation (PST) and increasing partially stochastic translation (IPST), which help in obtaining the antimultimodularity preservation in dynamic programming problems. We provide properties, sufficient conditions, and examples for PST and IPST functions. By applying PST and IPST, we obtain the antimultimodularity of the profit functions. The antimultimodular profit functions ensure that the optimal regular ordering quantity and the optimal price are monotone in the current inventory level and outstanding order quantities. Moreover, we reveal that as the time interval increases, the effects of previous outstanding orders on the optimal regular ordering and pricing decisions are decreasing and increasing, respectively. PST and IPST also enable us to further characterize the optimal expedited ordering quantity as decreasing in the inventory level. However, the optimal expedited ordering quantity can be non-monotone with respect to the outstanding order quantities, as shown in the example.     

考虑无转移支付的VMI系统Pareto改进

收益共享机制下的转移支付是影响供应商积极实施VMI的关键因素。在当前处于强势地位的下游企业不愿意提供转移支付的情况下,如何实现VMI系统的Pareto改进呢?将转移支付成本与物流供应商采用业务延伸策略为项目型企业提供终端产品所产生的成本领先优势进行比较发现,业务延伸策略下的VMI既弥补了无转移支付对供应商所造成的经济损失,又帮助项目型企业节省了实施自我服务策略时所投入的相关成本,如库存成本和加工设备成本,从而实现了VMI系统的Pareto改进。     

Low cost country sourcing and its effects on the total cost of ownership structure for a medical devices manufacturer

In this paper, we describe a total cost of ownership (TCO) method as an activity-based costing (ABC) application along the value chain to measure and analyse the costs of international sourcing activities. We further describe the method's implementation for a manufacturer of high-tech medical devices. For this case study, we analyse the effects of shifting purchasing volume from traditional procurement market suppliers to low cost country suppliers on the cost structure of purchasing projects. We find that particularly costs at component and supplier level gain importance over traditionally dominating unit level costs. Furthermore, we identify low cost country sourcing as a decision with extensive impact on value chain entities other than purchasing. Finally, a considerable part of costs in low cost country sourcing accrue at the beginning of a purchasing project due to problems stemming from unsatisfactory initial quality, language barriers and intercultural communication.     

Automotive supplier parks: An imperative for build-to-order?

Build-to-order (BTO) has been hailed as a production strategy that fits the demands of the 21st century where a considerable challenge for the industry is how to achieve flexibility from extended supply chains that span the globe and retain elements of make-to-forecast. A study of 8 European manufacturers examines whether supplier parks are an imperative for BTO using a conceptual framework developed from the literature. The findings question the idea that simply locating suppliers in close proximity to original equipment manufacturer assembly plants reduces delivery lead time and inventory. Hence, not all types of supplier parks are an imperative for BTO, where the cases reveal a wide variety of types ranging in scale and proximity. The originality of the paper is a unique study which redefines both automotive supplier park terminology and the relationships with BTO. It questions received wisdom and offers practical measures for industry.     

A multi-objective model for lot-sizing with supplier selection for an assembly system

Lot-sizing with supplier selection (LS-SS) is a fast-growing offspring of two major problem parents in logistics and supply chain management (‘lot-sizing’ and ‘supplier selection’). The model proposed in this paper is an attempt to extend it to an assembly system, by formulating a multi-objective model for an integrative problem of LS-SS for assembly items. The total costs of the system, consisting of purchasing, ordering, transportation, assembly, and holding, is considered the first objective function, while the total reliability of the finished products is considered the second objective function. The decision-maker aims to minimise the total costs while maximising the total reliability. Several constraints of the system (e.g. storage capacity, supplier production capacity) are taken into account. Given the complexity of the model, a heuristic evolutionary algorithm is proposed to solve the model. The results indicate which assembly items to order in which quantities, from which suppliers and in which time periods.     

Internal and external suppliers in manufacturing networks—An empirical analysis

The purpose of the paper is to explore the way manufacturing firms use internal and external suppliers in the design and management of manufacturing networks. The main area of interest is to explore the similarities and differences between internal and external suppliers, with respect to their roles and the reasons for choosing a certain type of supplier. We base our analysis on data from 104 Swedish manufacturing plants and their corresponding manufacturing networks of internal and external suppliers. The results of the study show that there are significant differences between the criteria that are influential in choosing a certain type of supplier. The choice of an internal supplier is largely based on a single corporate decision, while an external supplier has to perform well on a number of criteria (primarily quality, cost, and delivery dependability). When comparing the selection criteria with competitive priorities and plant performance, we find that the criteria for selecting external suppliers has a better match than those for selecting internal suppliers. The sample contained plants having only external suppliers as well as plants having both internal and external suppliers, but the selection criteria for external suppliers are the same for both groups and not dependent upon the presence or absence of internal suppliers.     

基于中心化存储和横向转运的选址——库存联合决策模型

针对单一产品、单周期、单一供应商、多配送中心、供应商和需求点位置已知的情况,假定（Q,R）库存检查策略、给定备选地址、无容量约束、各需求点的需求完全独立且均服从正态分布、配送中心级和需求级同时采取中心化安全库存策略、允许配送中心间及同一配送线路内的需求点间通过横向转运对缺货进行瞬间补充、不计缺货成本和转运时间,构建了二层规划模型。上层规划解决选址及需求点的分配问题;下层规划确定配送中心级和需求级的中心化存储方案。发现如果考虑库存持有成本、转运成本等因素的影响,安全库存的集中存放策略并不是聚集在某一个地方,而是在多个地方进行有限、适度的集聚,其成本更低。     

考虑责任违规中断的负责任采购博弈

随着全球供应链的发展,供应商过程违规越来越成为供应中断的常见原因。为改善过程合规性,很多跨国公司已经在全球范围内,尤其是发展中国家实施负责任采购。针对供应商-采购方过程行为建模内生化责任违规中断风险,构建采购方和风险供应商之间的Stackelberg博弈模型,研究订货比例、成本结构等对决策产生的影响。通过比较静态分析发现,在责任违规中断风险下,即使跨国公司的订单占比较小,风险供应商也有动力不断提高合规水平直至完全合规。这说明跨国公司可通过游说当地政府提高对过程违规行为的监管和惩罚,以此激励风险供应商提高合规努力。     

The effect of transaction costs, payment terms and power on the level of raw materials inventories

This paper proposes and tests an explanation for the level of raw materials inventories based on transaction cost economics theory and the role of power in a supply chain. According to this explanation, raw materials inventories are larger the higher a company's transaction costs and the lower its storage-related production and management costs. Factors that affect these costs are the company's vulnerability to opportunism, whether the input becomes more or less costly to store and manage as it moves through the supply chain, payment terms and the company's power in relation to its supplier. This explanation for the level of raw materials inventories was tested on a large sample of customer industries matched to their main supplier industries. Consistent with this theory, the empirical results show that companies hold larger raw materials inventories the more money their suppliers spend on research and development and the less important the customers are to their suppliers. These results are important because they indicate companies must consider a wider range of factors than previously thought necessary when establishing inventory policy.     

Supplier-managed inventory: schedule sharing

Supplier-managed inventory (SMI) is a methodology that provides a true win-win partnership between customers and suppliers. SMI supports flexibility for the customer to change schedules and flexibility to the supplier to decide when and how much to ship. All this is accomplished via electronic data interchange (EDI), which communicates the customer's gross requirements, inventory, and desired minimum/maximum inventory levels.     

Supplier development and cost management in Southeast Asia—Results from a field study

This paper is about supplier development when international companies have production sites in Southeast Asia and look for opportunities to switch from international suppliers to local suppliers. We conducted a field study involving site visits to companies in Thailand and Vietnam, and interviews at corporate supply chain departments. Some key observations are: cost management was a dominant motive for taking local supplier development initiatives. Furthermore, local sourcing and local supplier development were important for international companies to improve access to local customer markets. Firms deliberately assessed whether a particular supplier would likely be able to improve sufficiently to warrant investing in supplier development, which typically involved a combination of initiatives, requiring the international firm to take considerable efforts. Local sourcing strategies and priorities for supplier development initiatives tended to focus on items with low supply risk and low volume. These findings are discussed based on transaction cost economics, and we suggest that firms use several ways to reduce the risk of transaction-specific investments in supplier development initiatives.     

Supplier incentives and resource constraints under uncertainty

Procurement in environments of cost uncertainty and asymmetric information require special arrangements such as the linear incentive contract. Usually the buyer is motivated to make investments that can relieve temporary supplier resource constraints during the procurement. Special problems arise, however, due to interactions between investments in suppliers and the risk-incentive trade-off achieved by the incentive contract. A cost signaling model is proposed to overcome these problems, where a supplier offers an equity share in the profit from the incentive contract to the buyer in return for a priori investment. The equity share signals the supplier's private cost information, and forms the basis for the buyer's investment decision. Under equilibrium the buyer can expect to recover the entire amount provided to the supplier through his or her share of the profit.     

Do all suppliers dislike electronic reverse auctions?

Electronic reverse auctions (ERAs) are a controversial sourcing tool. While it is said to have many advantages to buyers, and even some to suppliers as well, it is also heavily criticised for damaging cooperative buyer–supplier relationships. It is often suggested that suppliers experience more disadvantages than advantages from the use of this tool and therefore many, if not all suppliers dislike ERAs. In this paper, we investigate whether all suppliers indeed dislike ERAs and we explore the relationships between supplier characteristics and supplier opinions of ERAs. We find that a small group of suppliers is actually positive about ERAs and that by far the strongest predictor of ERA opinions of a supplier representative is the supplier country.     

供应不确定下基于Supply-hub的供应商选择和库存协同决策

针对由供应商、Supply-hub和制造商组成的三级供应链的多产品供应商选择和库存协同问题,考虑供应商存在延迟交付风险、供应数量约束,以供应链运作成本最小为目标,构建整数规划模型。分析结果表明:在一定的条件下,总存在最优的供应商选择方案和库存策略;当供应商的延迟交付概率增加,供应链期望成本上涨;当供应商供应数量无限制时,减少最优订货批量可以弱化供应不确定性增加造成的影响;当供应商选择方案不变,订货提前期增加,供应链的运作成本以及最优订货批量不变;一种零部件提前期的变化不影响其他零部件的供应商选择和库存策略。     

The influence of reputation on supplier selection: An empirical study of the European automotive industry

Using an original database, integrated with information by the web, we propose an ex-post analysis on the main factors influencing the selection process of tier 1 suppliers in the automotive industry. There is plenty of literature on how buyers should select their suppliers, but the literature on how they really do so is scarce. We contribute analysing an original database collecting purchasing contracts information within the automotive components market in Europe. We investigate, through different econometric approaches the influence of traditional supplier selection criteria in combination with different reputation factors. Our findings suggest that reputation plays a crucial role more than classical criteria; in particular, suppliers, which serve a diversified customer portfolio or with strong exposure to premium brand customers have better chances to gain additional orders and broaden their customer base even more. The latter means that OEMs have to increase their reputation in order to be more attractive for suppliers.     

Supplier–supplier relationships in buyer–supplier–supplier triads: Implications for supplier performance

A growing number of studies and evidence from industries suggest that, besides managing the relationship with its suppliers, a buyer needs to proactively manage the relationships between those suppliers. In a buyer–supplier–supplier relationship triad, the buyer, as the contracting entity, influences the suppliers’ behaviors and the relationship between them. By considering the relationships in such a triad, we are able to gain a richer and more realistic perspective of buyer–supplier relationships. In this study, our goal is to examine supplier–supplier relationships in buyer–supplier–supplier triads, focusing on how such relationships impact the supplier performance. We frame the supplier–supplier relationship as co-opetition—one in which competing suppliers work together to meet the buyer's requirements. We investigate the role of the buyer on such relationships, and how the buyer and co-opetitive supplier–supplier relationships affect supplier performance. We find mixed empirical support for our hypotheses. However, we are able to demonstrate the dynamics of supplier–supplier co-opetition in the buyer–supplier–supplier triad. We point out the need for further studies in this area.     

Supplier empowerment: Mediating situational factors and perceived performance

The understanding of the behavioral and cognitive factors that affect organizations' performance has attracted increasing attention of scholars and practitioners. Based on the literature of psychological empowerment at the individual and the team levels, this study develops the concept of supplier empowerment in the context of purchasing and supply management. Further, this study proposes a research model that explores the role of supplier empowerment as a cognitive concept in mediating the relationship between situational factors (a supplier's process modularity and the mutual trust with its customers/buyers) and the supplier's perceived performance in its operations and customer service. This model is tested with 208 responses from automotive industry suppliers. The findings highlight the importance of empowered suppliers in decreasing inventory levels and increasing order fulfillment performance.