低碳经济下考虑满意度的冷链路径优化

为了在降低冷链物流配送成本的同时,保证顾客满意度和碳排放成本达到企业的要求。充分考虑客户软时间窗约束、行驶距离、生鲜变质等多重影响因素,构建考虑顾客满意度的低碳冷链物流路径优化模型,结合固定成本、碳排放成本、损坏成本、冷藏成本、运输成本以及时间窗成本,采用遗传算法进行求解,并应用实例加以验证。结果表明,相对于不考虑满意度的路径优化,以总成本为目标的冷链物流路径优化,能够平均减少23 km的运输距离和降低2.72%的配送总成本;同时结果也更优于以低碳为目标的求解。模型在提高顾客满意度的同时,实现了降低配送总成本以及减少物流活动中碳排放的目标。因此,研究为物流运输企业提高服务质量和经济效益提供了有效的技术路线,结果可为冷链物流行业的服务能力提升以及低碳转型发展提供启示,为物流行业的可持续发展研究提供理论参考。     

Efficient location of industrial activity cells in a global supply chain

Inefficient locations for production, distribution and reverse logistics plants will result in excess costs no matter how well material requirements planning (MRP), inventory control, distribution and information sharing decisions are optimized. In this paper we study ways in which aspect of activity cell location decisions can be analyzed within an extended MRP model. This model has previously been extended by including distribution and reverse logistics components in a compact form, presented in Grubbström et al. (2007). Our aim is to demonstrate the basic differences between an approach to location problems with MRP “under the same roof” as the global supply chain, in which transportation time delays and direct transportation costs have substantial influence. We discuss possibilities of how to present location aspects in the supply chain model obtained from combining input–output analysis and Laplace transforms in four sub-systems, namely manufacturing, distribution, consumption and reverse logistics, and show how the transportation costs and lead time influenced by the location of all these activities affect the resulting net present value (NPV). Our aim is to build a model supporting decisions concerning the structure of a supply chain as an alternative to a mixed integer programming formulation. The model developed is based on the use of continuous functions describing spatial distributions of cost and customer demand. Continuous functions are embedded in the MRP extension previously introduced in Grubbström et al. (2007).Location decisions influence (i) production costs, because timing influences the cost of activities involved in creating a product, cf. (Grubbström and Bogataj, submitted for publication), and (ii) logistics costs, which refer to the procurement and physical transmission of materials through the supply chain. In this current paper we wish to combine both of these aspects into a comprehensive model, where we show the interaction between the “space of flows” and the “space of places” as Giovanni Arrighi distinguishes one from the other in his book The Long Twentieth Century.     

Bundling digitized logistics activities and its performance implications

Bundling information technology (IT) applications to support logistics activities provides a means for firms to improve their logistics performance. Grounded in the logistics management and management information systems literature, as well as the resource-based view (RBV) of the firm, this study empirically: (i) investigates if there exist digitized logistics activities bundles in firms; and if so, (ii) explores the association between digitized logistics activities bundles and logistics performance of firms in terms of logistics cost and logistics service improvements. We surveyed 227 trading firms in Hong Kong and performed a factor analysis of the survey data, from which we identified three digitized logistics activities bundles and found the sample firms were clustered into four types based on the patterns of their digitized logistics activities. We then carried out a MANOVA on the data, the results of which show that different patterns of digitizing logistics activities are associated with different logistics performance outcomes. Specifically, firms with more extensive digitized logistics activities bundles and utilizing them more intensively achieve better logistics performance. Academic and managerial implications for digitizing logistics activities to improve logistics performance are discussed.     

全球价值链的“空间逻辑”及其区域政策含义——基于制造组装环节与品牌营销环节空间分离的视角

本文运用一般均衡及超边际分析方法,通过建立一个包含制造组装环节和品牌营销环节的内生分工模型来探索全球价值链的"空间逻辑"。研究表明:促进制造组装环节与品牌营销环节空间分离的主要动力有两个:一是发挥各个区域的外生比较优势,最大限度地提高整条价值链的生产效率;二是充分利用各个区域的专业化经济,尽量降低整条价值链的固定学习成本。而要实现制造组装环节和品牌营销环节的空间分离,需要制造产品以及品牌服务的区域间交易效率提高到一定的临界值,其中,品牌服务在提高市场交易效率方面的"正反馈效应"对上述两个环节空间分离的实现起着促进作用。在此基础上,本文进一步分析了模型衍生的一系列区域经济政策含义。     

冷链物流“最后一公里”快速配送方法研究

冷链物流“最后一公里”的品质配送，对于实现全程冷链以及提升企业形象有着重要的意义。为了实现冷链物流的快速配送，本文提出了一种基于复杂网络的“最后一公里”物流配送区域划分方法。该方法构建了现实生活中物流配送的复杂网络模型，然后基于两阶段的LinkRank社区发现算法实现了物流配送区域的划分，最后建立了一套完善的物流配送体系。该体系明确了配送中转站以及配送点所覆盖的区域，这些区域所包含的社区物流关系紧密、易于配送。本文通过案例研究，验证了方法的有效性，最终方案可有效提高“最后一公里”的配送效率和降低物流成本。     

Optimal safety stock levels of subassemblies and manufacturing components

In order to control the time to market and manufacturing costs, companies produce and purchase many parts and components before receiving customer orders. Consequently, demand forecasting is a critical decision process. Using modular product design and super bills of materials are two effective strategies for developing a reliable demand forecasting process. They reduce the probability of stockouts in diversified production contexts. Furthermore, managing and controlling safety stocks for pre-assembled modules provide an effective solution to the problem of minimizing the effects of forecast errors. This paper develops, evaluates, and applies innovative cost-based analytical models so that the optimal safety stock of modular subassemblies and components in assembly to order and manufacturing to order systems, respectively, can be rapidly quantified. The implementation of the proposed models in two industrial case applications demonstrates that they significantly reduce the safety stock inventory levels and the global logistical cost.     

An integrated production–distribution model for the dynamic location and allocation problem with safety stock optimization

The design and management of a multi-stage production–distribution system is one of the most critical problems in logistics and in facility management. Companies need to be able to evaluate and design different configurations for their logistic networks as quickly as possible. This means coordinating the entire supply chain effectively in order to minimize costs and simultaneously optimize facilities location, the allocation of customer demand to production/distribution centers, the inbound and outbound transportation activities, the product flows between production and/or warehousing facilities, the reverse logistics activities, etc.Full optimization of supply chain is achieved by integrating strategic, tactical, and operational decision-making in terms of the design, management, and control of activities. The cost-based and mixed-integer programming model presented in this study has been developed to support management in making the following decisions: the number of facilities (e.g. warehousing systems, distribution centers), the choice of their locations and the assignment of customer demand to them, and also incorporate tactical decisions regarding inventory control, production rates, and service-level determination in a stochastic environment. This paper presents an original model for the dynamic location–allocation problem with control of customer service level and safety stock optimization. An experimental analysis identifies the most critical factors affecting the logistics cost, and to finish, an industrial application is illustrated demonstrating the effectiveness of the proposed optimization approach.     

Coordinated supply chain scheduling

A mixed integer programming approach is proposed for a long-term, integrated scheduling of material manufacturing, material supply and product assembly in a customer driven supply chain. The supply chain consists of three distinct stages: manufacturer/supplier of product-specific materials (parts), producer where finished products are assembled according to customer orders and a set of customers who generate final demand for the products. The manufacturing stage consists of identical production lines in parallel and the producer stage is a flexible assembly line. The overall problem is how to coordinate manufacturing and supply of parts and assembly of products such that the total supply chain inventory holding cost and the production line start-up and parts shipping costs are minimized. A monolithic approach, where the manufacturing, supply and assembly schedules are determined simultaneously, is compared with a hierarchical approach. Numerical examples modeled after a real-world integrated scheduling in a customer driven supply chain in the electronics industry are presented and some computational results are reported.     

An investigation of setup instability in non-stationary stochastic inventory systems

In stochastic inventory systems unfolding uncertainties in demand lead to the revision of earlier replenishment plans which in turn results in an instability or so-called system nervousness. In this paper, we provide the grounds for measuring system nervousness in non-stationary demand environments, and gauge the stability and the cost performances of (R,S) and (s,S) inventory policies. Our results reveal that, both the stability and the cost performance of inventory policies are affected by the demand pattern as well as the cost parameters, and the (R,S) policy has the potential to replace the cost-optimal (s,S) policy for systems with limited flexibility.     

Supermarket contracts and smallholder farmers: Implications for income and multidimensional poverty

Food systems in developing countries are changing rapidly with a growing role of modern supermarkets. Supermarkets influence supply chains and the way agricultural products are sourced from farmers. Especially for the procurement of fresh fruits and vegetables, supermarkets often contract farmers directly to ensure consistent and high-quality supply. One important question, which is addressed here, is whether smallholder farmers benefit from supermarket contracts. Previous studies address this question, but mostly focus on income effects without exploring implications for other dimensions of household welfare, such as nutrition, health, or housing conditions. Moreover, most existing studies rely on cross-section data. We add to the literature by analyzing effects of supermarket contracts on income and multidimensional poverty using three rounds of panel data collected from smallholder vegetable farmers in Kenya and econometric models with household fixed effects. On average, supermarket contracts increase household income by over 40%. We also find significant reductions in income poverty and multidimensional poverty. Quantile regressions show that farmers in all income groups benefit, but richer households benefit more than poorer ones in absolute terms. However, supermarket contracts cause the strongest reductions in multidimensional deprivations among the poorest households.     

基于变邻域搜索算法的物流配送系统集成优化研究

本文针对物流配送系统集成优化问题,考虑取货和送货两种业务的配送情形下仓库和车辆的容量上限约束,构建包括仓库的开放成本、配送成本以及容量溢出成本的非线性混合整数优化模型,设计变邻域搜索启发式算法对模型进行求解。算法通过泰森多边形确定位置上的初始订单分配,再通过扫描半径及消费者数据结构标识实现邻域搜索,改进算法对解决方案进行迭代更新,完成优化求解。最后通过对辽宁宅急送取／送一体化物流配送案例进行数值分析,验证算法可行性和有效性。     

The rise of supermarkets and changing expenditure patterns of poor rural households case study in the Transkei area,South Africa

Since the late 1990s, the number of supermarkets in South Africa has been steadily growing. Due to a more effective and efficient management and procurement system, the supermarkets can benefit from economics of scale and sell food at a relative low price. In this paper, we present a case study of two villages in the Transkei area of South Africa. In these poor rural communities, the majority of households now buy their main food items from supermarkets rather than from local shops and farmers. While presenting an important step towards livelihood development and food security, these supermarkets form also a strong competitor for local agricultural sales. The supermarkets provide many food items at lower prices. With an increase in income, the households look for variety and exotism in their food products, and will most likely find this in the supermarkets, rather than the local stores. We argue therefore that development programs should focus on the local growers’ access to the supermarket procurement systems.     

Design of the optimal feeding policy in an assembly system

This paper describes an innovative and integrated approach to component management optimization within a production/assembly system. In a mixed-models assembly process the handling of parts and components for each work station represents a substantial variable that can greatly affect job duration and efficiency. This paper is strictly related to Assembly to Order/Manufacturing to Order (ATO and MTO) systems, where lead time has to be very short and flexibility is at its maximum level. In Assembly to Order (ATO) or Make to Order (MTO) systems, the production is increasingly getting more customized in response to the demand, thanks to the progresses reached in both manufacturing and information technologies. It is becoming increasingly possible to assemble or make products specifically in response to the requests of either end customers or retailers. As a consequence of such customization, the design of the whole system must take into direct account several elements: parts warehouses location, feeding policies and feeding systems. In some cases the collection of parts and components required picking activities, in other the movement of entire units load.In several instances experts have analyzed the problems about material centralization/decentralization, storage policies and assembly feeding problem in different and independent ways, while the problem needs an integrated approach. While many researches regarding components allocation problems in ATO and MTO systems, did not consider feeding policies, material picking, packing activities and vehicles optimization, this paper cover focuses on filling such gap using an integrated framework that considers both aspects of the problem: the centralization/decentralization of components in order to minimize the total storage costs and the right feeding policies.Feeding problems in assembly lines are some of the most important aspects to consider during the analysis and design of an assembly system, to allow the maximization of efficiency and flexibility. To reach such goals, a multi-factorial analysis has been carried out during this experiment and will validate the introduced framework. An industrial application of the introduced framework is illustrated to explain its real significant production implication.     

Near-optimal (r,Q) policies for a two-stage serial inventory system with Poisson demand

We consider a two-stage serial inventory system whose cost structure exhibits economies of scale in both stages. In the system, stage 1 faces Poisson demand and replenishes its inventory from stage 2, and the latter stage in turn orders from an outside supplier with unlimited stock. Each shipment, either to stage 2 or to stage 1, incurs a fixed setup cost. We derive important properties for a given echelon-stock (r, Q) policy for an approximation of the problem where all states are continuous. Based on these properties, we design a simple heuristic algorithm that can be used to find a near-optimal (r, Q) policy for the original problem. Numerical examples are given to demonstrate the effectiveness of the algorithm.     

Performance evaluation of production systems monitored by statistical process control and off-line inspections

Quality and productivity performance measures are very often considered in separate phases of the production system design process. However, the production system architecture affects the efficiency of the quality control system as well as the quality control configuration has an impact on the performance of the production system.The paper proposes a new analytical method for evaluating the performance of production systems in which statistical process control (SPC) techniques are implemented. Machines behaviour is monitored by measuring quality characteristics of the produced parts through off-line inspection devices and sampling inspections. The numerical results show the good accuracy of the proposed method, provide new insight in the relations among the two areas and pave the way to the joint design of production logistics and quality control systems.     

Stocking decisions for repairable spare parts pooling in a multi-hub system

This paper presents an analytical model for determining spare parts stocking levels in a single-item, multi-hub, multi-company, repairable inventory system in which complete pooling of stock is permitted among the hubs and companies. The objective is to minimize the total system cost which consists of inventory holding cost, downtime cost and transshipment cost. We develop an approximation method to compute the logistical system performance measures needed for calculating the cost function. To find the optimal stocking levels, a two-stage solution is proposed. In the first stage, the demands at all hubs are aggregated and treated as if occurring at a single location. The optimal number of total spare parts is determined by minimizing the sum of inventory holding cost and downtime cost. In the second stage, a heuristic procedure is developed to find the optimal allocation of the total spare parts to minimize the total transshipment cost.     

对国有石化企业发展物流的再思考

国有石化企业的物流部门具备较好的运输设备,但目前仍处于传统储运业的阶段,无法满足具有国际先进水平石化企业物流的需要.随着石化行业的快速发展,物流量不断增大,各种所有制的石化企业数量也不断增加,国有石化企业可以运用现代物流理论和信息技术,整合原有的采购、运输、仓储等部门,组建第三方物流企业.这样,可降低运作成本,提高效率,不仅满足原石化企业的物流需要,更可满足社会上石化企业的需要,并创造大量利润.在物流信息化中,应重点关注物流运作、客户服务等环节.     

Supply network dynamics as a source of new business

Supply networks where operational control extends well over organizational boundaries have emerged in industries producing relatively complex and customized products with tight profit margins. Products like ships, automobiles and telecommunication systems incorporate complex design and engineering skills that are produced through a tier-structured, multi-level supply networks. Efficiency in these networks has stemmed from specialization and cost efficiency in individual value adding operations. This paper demonstrates how supplier networks have evolved and how the inherent dynamics of these networks generate constantly new business opportunities for fast moving companies with a clear focus on operational efficiency. We use action research methodology on cases from the shipbuilding and constructions industry to document some of the dynamic features of supply networks. This insight is then applied to the electronics manufacturing services business to explain the fundamentals of successful operations in this highly competitive business with ever narrowing margins. In this dynamic market of contract manufacturing companies with constant focus on the reduction of production lead times by incorporating value added operations either physically or logically to maintain and recreate profitable business. To succeed in doing this, issues related to industrial parks, local tacit knowledge and reverse/repair logistics must be managed in cross-organizational manner. We conclude that there is an ever-changing limit to the expansion of supplier networks through specialization and cost efficiency, and that at one point contracting and integrating parts of the supply network will create operationally outperforming business models that further boost the inherent dynamics of supply networks.     

Quantifying the costs of a nationwide public safety wireless network

The existing US public safety wireless infrastructure consists of thousands of disparate systems built by separate local agencies. Problems with interoperability, cost, spectral efficiency, and limited functionality plague these systems but could be significantly reduced through the deployment of a single nationwide network that serves all public safety personnel. Two major efforts towards such a nationwide network are the federal-government-only Integrated Wireless Network (IWN) and an FCC-led effort to create a public-private partnership in the 700 MHz band; the future of both projects is uncertain due in part to concerns surrounding cost. This paper presents a model to estimate cost for two fundamental approaches to a nationwide network: a public-safety-only network and a public–private partnership which serves both public safety and commercial subscribers. We apply this general model to four network scenarios which differ in the amount and band of spectrum allocated as well as the number and type of subscribers (public-safety-only versus commercial and public safety) under three traffic scenarios: voice-only, data-only, and voice and data. We demonstrate that the nation's many small systems could be replaced with a single nationwide network with a small fraction of the tower sites and spectrum. The cost of building this new infrastructure is comparable to what is likely to be spent in just a few years on upgrading and maintaining the existing infrastructure. In addition, we show that these cost estimates are highly dependent on some key system design parameters including the public safety capacity required and signal coverage reliability, which must therefore be well-defined in advance.     

The selected determinants of manufacturing postponement within supply chain context: An international study

Modern supply chains focus on an ultimate consumer satisfaction and often require essential dynamic reconfiguration. Manufacturing companies constitute important central nodes in supply chains, where almost all physical flows are concentrated.Postponement is the operating concept, which aims at delaying activities until a customer’s order has been received. The growth of interest in the postponement concept partially results from the increased demand for customized products.Data for the analysis has been collected through the survey carried out by researchers in several countries. The main research instrument used for this research was a questionnaire developed by the Global Manufacturing Research Group (GMRG). The conclusions formulated on the basis of data analysis proved that market and demand characteristics do not seem to be important for the choice between postponement and speculation strategy. The research showed that assembly postponement depends mostly on managerial decisions about the goals of company and the level of acceptance of an assembly postponement strategy on the market. Full postponement strategy is dictated mainly by the level of product customization and capacities of manufacturing and logistics systems. Production postponement has to be accepted on the market and should be associated with excellent forecasting techniques.