Monolithic versus hierarchical approach to integrated scheduling in a supply chain

The two approaches, monolithic and hierarchical, with a set of mixed integer programming formulations are proposed and compared for multi-objective integrated scheduling in a customer driven supply chain. The supply chain consists of multiple manufacturers (suppliers) of parts, a single producer of finished products and a set of customers who generate final demand for the products. Each supplier has a number of identical production lines in parallel for the manufacture of parts, and the producer has a flexible assembly line for assembly of products. Given a set of orders, the problem objective is to determine which orders are to be provided with parts by each supplier, find a schedule for the manufacture of parts by each supplier and for the delivery parts from each supplier to the producer, and find a schedule for the assembly of products for each order by the producer, such that a certain performance measure of the supply chain is optimised. The selection of the parts supplier for each order is combined with due date setting for some orders, subject to the suppliers and the producer available capacity. Different objective functions are considered that take into account both customer service level and total manufacturing, delivery and production cost. Numerical examples are presented that are modelled by real-world integrated scheduling in a customer driven supply chain of high-tech products, and some computational results are reported to compare the two approaches.     

A three-stage model for closed-loop supply chain configuration under uncertainty

In this paper, a general closed-loop supply chain (CLSC) network is configured which consists of multiple customers, parts, products, suppliers, remanufacturing subcontractors, and refurbishing sites. We propose a three-stage model including evaluation, network configuration, and selection and order allocation. In the first stage, suppliers, remanufacturing subcontractors, and refurbishing sites are evaluated based on a new quality function deployment (QFD) model. The proposed QFD model determines the relationship between customer requirements, part requirements, and process requirements. In addition, the fuzzy sets theory is utilised to overcome the uncertainty in the decision-making process. In the second stage, the closed-loop supply chain network is configured by a stochastic mixed-integer nonlinear programming model. It is supposed that demand is an uncertain parameter. Finally in the third stage, suppliers, remanufacturing subcontractors, and refurbishing sites are selected and order allocation is determined. To this end, a multi-objective mixed-integer linear programming model is presented. An illustrative example is conducted to show the process. The main novel innovation of the proposed model is to consider the CLSC network configuration and selection process simultaneously, under uncertain demand and in an uncertain decision-making environment.     

Maintenance supplier selection considering life cycle costs and risks: a fuzzy goal programming approach

In this study, we address a new variant of supplier selection problem named maintenance supplier selection problem faced by a manufacturer. The production system consists of different multi-component equipments whose maintenance activities require several components (parts) each of which could be provided by multiple suppliers. A multi-objective mathematical model is developed to decide about the supply base of each part as well as the purchasing quantity of each part from each selected supplier. The model accounts for the total life cycle costs of purchased parts and various risks threatening the candidate suppliers. A fuzzy/soft lexicographic goal programming approach with soft priorities between objectives is proposed to enable the decision-maker to make preferred trade-offs between objectives by which the effects of various risks in each phase of life cycle of procured parts are investigated. The capability and effectiveness of the proposed model is validated through a case study. Some sensitivity analyses are also carried out for investigating the impact of cost, risk and objectives’ priorities on the final preferred compromise solution. Finally, some managerial insights and concluding remarks are provided.     

Supply chain design to guarantee quoted lead time and inventory replenishment: model and insights

Do lead time constraints only lead to re-think and re-optimise the inventory positioning along the supply chain or can they impact on the design of the supply chain itself? To answer such a question, we integrate the lead time constraints in a multi-echelon supply chain design model and challenge the difficulty of combining in the same model the long-term decisions (facility location, supplier selection) with the midterm decisions (inventory placement and replenishment, delivery lead time). The model guarantees the respect of the quoted lead time associated with each customer order and the replenishment of the different stocks (raw materials, intermediate and final products) in the different stages of the supply chain between any pair of consecutive orders. We use the model to investigate the impact of the quoted lead time and customer’s order frequency on supply chain design decisions and costs. Some of our results indicate that the lead time constraints can lead to bringing the sites of manufacturing and distribution close to the demand zone and to select local suppliers in spite of their higher cost.     

基于犹豫模糊语言术语的供应商多准则群决策研究

针对全球价值链环境下供应商科学决策问题,提出基于不确定语言术语的多准则群决策模型。首先分别提取专家的偏好信息,将偏好信息转化为犹豫模糊语言术语,引入不确定语言变量进行词计算;其次,运用包络算子融合专家的偏好信息形成犹豫模糊语言术语集,设计集成准则权重的相对贴近度进行产品供应商排序,确定最满意供应商;此外,引入信息熵求解决策过程无先验知识的多准则权重;计算结果表明：3种信息熵参数条件下最满意汽车零部件供应商选择结果完全一致,基于相对贴近度值的供应商优劣排序结果相对于信息熵参数变化不敏感;验证了所提模型可行性、有效性和稳定性,为汽车零部件供应商的实际评价与选择提供有益借鉴。     

On the robust decision-making in a supply chain under disruption risks

This paper considers a robust decision-making problem associated with supplies of parts and deliveries of finished products in a customer driven supply chain under disruption risks. The robustness refers to an equitably efficient performance of a supply chain in average-case as well as in the worst-case, which reflects the decision-makers common requirement to maintain an equally good performance of a supply chain under different conditions. Given a set of customer orders for products, the decision-maker needs to select suppliers of parts required to complete the orders, allocate the demand for parts among the selected suppliers and schedule the orders over the planning horizon, to equitably optimise average and worst-case performance of the supply chain. The supplies are subject to independent random local and regional disruptions. The obtained combinatorial stochastic optimisation problem is formulated as a mixed-integer program with conditional value-at-risk as a risk measure. The ordered weighted averaging aggregation of the expected value and the conditional value-at-risk of the selected optimality criterion is applied to obtain a robust solution. The risk-neutral, risk-averse and robust solutions that optimise, respectively average, worst-case and equitable average and worst-case performance of a supply chain are determined and compared for cost and customer service level objective functions. Numerical examples and computational results, in particular comparison with the mean-risk approach, are presented and some managerial insights are reported.     

Developing a resilient supply chain through supplier flexibility and reliability assessment

In this study, we examine the optimal allocation of demand across a set of suppliers in a supply chain that is exposed to supply risk and environmental risk. A two-stage mixed-integer programming model is used to develop a flexible sourcing strategy under disruptions. Our model integrates supplier selection and demand allocation with transportation channel selection and provides contingency plans to mitigate the negative impacts of disruptions and minimise total network costs. Finally, a numerical example is presented to illustrate the model and provide insights. The findings suggest that developing contingency plans using flexibility in suppliers’ production capacity is an effective strategy for firms to mitigate the severity of disruptions. We also show that flexibility and reliability of the suppliers and regions play a significant role in determining contingency plans for during disruption. Findings generally show that highly flexible suppliers receive less allocation, and their flexible capacity is reserved for disruptions. For firms that do not incorporate risk management into supplier selection and allocation, the recommendation is to source from fewer, more reliable suppliers with less risk of disruption. Our findings also emphasise that the type of disruption has important implications for supplier selection and demand allocation. This study highlights the supply chain risk management strategy of regionalising as a means for minimising the impact of environmental disruptions.     

产品生命周期过程(横向集成)供应商选择模型研究

通过分析集成化供应链管理环境下供应商选择过程,给出了选择指标体系及选择步骤。在此基础上,建立了“横向”集成型企业供应商选择的模糊综合评价选择模型。应用此模型可对选择最满意的供应商做出相应的决策。     

Supply chain flexibility concepts,dimensions and outcomes: an organisational capability perspective

Due to the increasing uncertainty and diversity in supply chains (SCs), companies are aiming to develop their SC flexibility, which we define as the capability of a company, both internally and externally in conjunction with its key suppliers and customers, to respond to uncertainties and customer expectations without excessive costs, time and performance losses. SC flexibility has three dimensions – internal, supplier and customer flexibility. This study investigates how SC flexibility improves operational and financial performance from the organisational capability perspective. The conceptual model is empirically tested using data collected from 216 companies in China. Our findings suggest that only customer and internal flexibility contribute to operational performance directly, while supplier flexibility contributes to operational performance only indirectly through internal flexibility. The three dimensions of SC flexibility have no direct impacts on financial performance. We further identify complementarities between supplier and customer flexibility and tradeoffs between supplier and internal flexibility. However, no synergy effect is found for internal and customer flexibility on operational performance. This study provides a framework to understand SC flexibility from the organisational capability perspective and identifies the inter-relationships among the three dimensions of SC flexibility and operational and financial performance.     

Global supplier selection: a fuzzy-AHP approach

Global supplier selection has a critical effect on the competitiveness of the entire supply chain network. Research results indicate that the supplier selection process appears to be the most significant variable in deciding the success of the supply chain. It helps in achieving high quality products at lower cost with higher customer satisfaction. Apart from the common criteria such as cost and quality, this paper also discusses some of the important decision variables which can play a critical role in case of the international sourcing. The importance of the political-economic situation, geographical location, infrastructure, financial background, performance history, risk factors, etc., have also been pointed out in particularly in the case of global supplier selection. Supplier selection problem related to the global sourcing is more complex than the general domestic sourcing and as a result it needs more critical analysis, which could not be found properly in past available literatures. This paper discusses the fuzzy based Analytic Hierarchy Process (fuzzy-AHP) to efficiently tackle both quantitative and qualitative decision factors involved in selection of global supplier in current business scenario. The fuzzy-AHP is an efficient tool to tackle the fuzziness of the data involved in deciding the preferences of the different decision variables involved in the process of global supplier selection. The triangular fuzzy numbers are used to transform the linguistic comparison of the different decision criteria, sub-criteria and performance of the alternative suppliers. The pairwise comparison matrices help in deciding the synthetic extent value of each comparison and finally, the priority weights of one alternative over another are decided in this paper. An example from a manufacturing industry searching for the global supplier for a critical component is used to demonstrate the effective implementation procedure of proposed fuzzy-AHP technique. The proposed model can provide the guidelines and directions for the decision makers to effectively select their global suppliers in the current competitive business scenario.     

基于不确定语言信息的物流供应商选择

为解决传统供应商的选择与评价过程中专家评判的模糊性和不确定性问题,提出了一种基于不确定语言信息的物流服务供应商选择方法。该方法以不确定语言变量来表征专家的评判从而避免了决策信息的丢失。继而建立了物流服务质量评价属性的权重优化模型,并构造拉格朗日函数来求解该模型,得到评价属性的最优权重。接着利用不确定语言加权几何平均（ULWG）算子集结专家评判信息,则得到供应商的优先排序。给出了基于不确定语言信息的供应商选择的算法步骤和应用实例。     

Integrated model for supplier selection and negotiation in a make-to-order environment

The paper deals with the development of an integrated supplier selection and negotiation process for multiple parts/materials procurement. The main objective is to integrate decisions in the internal supply chain of a make-to-order manufacturer. Two main decisions during the negotiation process are considered: (1) the manufacturing planning decision responsible for determining the production schedule and fabrication lot size and (2) the supplier selection decision concerning which suppliers are selected for company business and the order volume allocated to each selected supplier. The model is designed to support the negotiation process by generating a set of effective alternatives in each negotiation period. Its structure is multi-objective and non-linear. The combination of the interactive weighted Tchebycheff method and Benders decomposition method is applied to generate a set of effective alternatives to support the decision-maker in each negotiation period.     

Development and evaluation of the interactive bidding strategies for a demander and its suppliers in supplier selection auction market

Supplier selection strategy is a critical issue in a supply chain management (SCM) system. Selecting the correct suppliers can have a significant impact on the competitiveness of firms. This research is concerned with the development of the interactive bidding strategies for a demander and its multiple suppliers in a supplier selection auction market (SSAM). The objective of this paper is to investigate the negotiation efficiency for the various bidding strategies the demander employed in different order conditions. The negotiation efficiency is assumed as the required negotiation times to achieve an agreement, agreed price and the procurement costs. Further, this paper runs the experiments of SSAM and provides a bidding strategy guideline for a demander to achieve its goals of supplier selection in varying order conditions. To this end, the negotiation efficiency of this proposed bidding strategy model is compared with other research.     

价格不确定供应链的多目标运作鲁棒模型

建立了由一个制造商和一个供应商构成的多产品、多阶段供应链在原材料和最终产品的市场价格均不确定情况下运作的鲁棒模型.采用区间不确定性描述价格的不确定性.供应链的运作模型为一个多目标规划问题,满足诸如供应链协调运作、所有供应链成员的目标利润尽可能最大、对应于不确定供求价格的决策的鲁棒性等多个相互冲突的目标.数值算例的结果表明,一定范围内的市场价格波动不改变供应链的运作策略,仅对其运作性能产生一定影响,即所提出的模型是鲁棒的.     

Supplier selection and order allocation in closed-loop supply chain systems using hybrid Monte Carlo simulation and goal programming

Supplier selection is an important strategic design decision in closed-loop supply chain systems. In addition, and after identifying the candidate suppliers, optimal order allocations are also considered as crucial tactical decisions. This research presents a multi-objective optimisation model to select the best suppliers and configure manufacturing and refurbishing facilities with the optimal number of parts and products in a closed-loop supply chain network. The objective functions in this research are formulated as total profit, total defective parts, total late delivered parts and economic risk factors of the candidate suppliers. The proposed multi-objective model is solved by hybrid Monte Carlo simulation integrated with three different variants of goal programming method. The effectiveness of the mathematical model and the proposed solution algorithms in obtaining Pareto-optimal solutions is demonstrated in a numerical example adopted from a real case study.     

一体化供应链下的项目采购管理与供应商管理战略

本文针对汽车行业讨论了产品项目开发中采购管理的重要作用,根据目前项目采购中暴露出的问题,总结出项目采购管理其实质即为对供应商战略管理的理念,从而提出在一体化供应链下项目采购管理中对供应商管理的战略模型。该模型包括四个路径:"构造供应商库,选择和评价供应商,供应商参与项目开发,定义目标供应商平台",并体现如何应用该模型以提高一体化供应链的竞争性。     

Employing dynamic fuzzy membership functions to assess environmental performance in the supplier selection process

The proposed system illustrates that logic fuzzy can be used to aid management in assessing a supplier's environmental performance in the supplier selection process. A user-centred hierarchical system employing scalable fuzzy membership functions implement human priorities in the supplier selection process, with particular focus on a supplier's environmental performance. Traditionally, when evaluating supplier performance, companies have considered criteria such as price, quality, flexibility, etc. These criteria are of varying importance to individual companies pertaining to their own specific objectives. However, with environmental pressures increasing, many companies have begun to give more attention to environmental issues and, in particular, to their suppliers’ environmental performance. The framework presented here was developed to introduce efficiently environmental criteria into the existing supplier selection process and to reflect on its relevant importance to individual companies. The system presented attempts to simulate the human preference given to particular supplier selection criteria with particular focus on environmental issues when considering supplier selection. The system considers environmental data from multiple aspects of a suppliers business, and based on the relevant impact this will have on a Buying Organization, a decision is reached on the suitability of the supplier. This enables a particular supplier's strengths and weaknesses to be considered as well as considering their significance and relevance to the Buying Organization.     

The impact of contract parameters on the supply chain performance under different power constellations

Reporting forecast data is a common method used to improve the functioning of supply chains (SCs) and to reduce supply shortages. Customers tend to report the maximum possible demand as a forecast if restrictions are missing. Such a forecast is useless for suppliers. Hence, special contracts are needed to enhance the value of forecast data and therefore the cooperation between SC partners. In this paper, such a contract is presented. It encourages the customer to report a more realistic forecast. Deviations from the reported forecast are punished in different ways: If the customer reported too much and wants to release less than what was reported, he has to pay a penalty. On the other hand, the customer has the flexibility to purchase more than reported to meet the demand on his outlet but at the cost of an additional fee. This paper analyses how different contract parameters affect the performance of the SC, in particular when the bargaining power of customer and supplier is not equally distributed. Results show that the supplier and therefore the SC is better off if the supplier leaves the contractual cost parameters untouched but hides the true value of flexibility, especially when the customer is less powerful than the supplier.     

Impact of risk aversion and backup supplier on sourcing decisions of a firm

This study focuses on a newsvendor problem with multiple suppliers, considering the risk-neutral and risk-averse objectives in a mean-risk optimisation model. The firm first decides order quantities from the primary (unreliable) suppliers and reserve capacity from the secondary (reliable) backup supplier. After the state of its primary suppliers and customer demand is revealed, the firm purchases from the available suppliers and uses the backup supplier subject to the reserved capacity. For the special case of normal distribution and risk-neutral objective, optimality properties were developed. A comprehensive numerical study examines the sensitivity of the sourcing strategies of firms to risk, shortage cost, demand uncertainty, salvage value, and capacity reserve options; various managerial insights are offered based on this.