The role of elasticity in supply chain performance

This paper develops a model that describes the performance of supply chains based on their elasticities of supply and demand. The model can be used to predict a supply chain's ability to respond to supply interruptions, cost increases, and demand shifts, while also quantifying the degree to which it is prone to the bullwhip effect. The bullwhip effect is a behavioral phenomenon by which orders are distorted as they are transmitted through the chain. Four types of supply chains are identified and their distinct operating characters are examined. The impact of rival firms and the impact of a decoupling point on supply chain performance are also examined.     

A supply chain as a series of filters or amplifiers of the bullwhip effect

The bullwhip effect refers to the phenomenon of amplification and distortion of demand in a supply chain. By eliminating or controlling this effect, it is possible to increase product profitability reducing useless costs such as stock-out and obsolescence costs. The main focus of this work is to study a single-product serial supply chain in which a control parameter can switch the chain from a series of filters to a series of amplifiers of the bullwhip effect and to analyse how the optimal values of the parameters change when discontinuities in order policy are considered. Furthermore, it is also shown that the bullwhip itself it is not a good index of the chain's performance, because it does not consider the oscillations that occur in the inventories, which also may affect the supply-chain performance.     

基于促销行为的供应链牛鞭效应分析

供应链中的牛鞭效应起源于管理者追求利润最大化的理性决策,价格波动是产生牛鞭效应的主要原因之一,而价格波动常常是由零售商周期性地采取一些特殊促销行为引起的.本文通过考虑在动态需求环境下,存在一个包含有一个供应商与一个零售商的简单供应链,当下游零售商有促销行为时与无促销行为时进行定量分析比较,并分析基于促销行为的零售商收益大于库存成本时的牛鞭效应,结果表明,零售商的促销行为很大程度上加剧了牛鞭效应,只有当产品价格比较稳定时,才能尽量避免和减少牛鞭效应.     

The analysis of bullwhip effect in a HMMS-type supply chain

The aim of the paper is to investigate the well-known bullwhip effect of supply chains. Control theoretic analysis of bullwhip effect is extensively analyzed in the literature with the Laplace transform. This paper tries to examine the effect for an extended Holt-Modigliani-Muth-Simon model. A two-stage supply chain (supplier-manufacturer) is studied with quadratic costs functional. It is assumed that both firms minimize the relevant costs. The order of the manufacturer is delayed with a known constant. Two cases are examined: supplier and manufacturer minimize the relevant costs decentralized, and a centralized decision rule. The question is answered, how to decrease the bullwhip effect.     

The bullwhip effect in capacitated supply chains with consideration for product life-cycle aspects

This paper presents an analysis of the bullwhip effect and net-stock amplification in a three-echelon supply chain considering step-changes in the production rates during a product's life-cycle demand. The analysis is focused around highly complex and engineered products (e.g., automobiles), that have relatively long production life-cycles and require significant capital investment in manufacturing. Using a simulation approach, we analyze three stages of the product life-cycle including low volumes during product introduction, peak demand, and eventual decline toward the end of the life-cycle. Parts of the simulation model have been adopted by a major North-American automotive OEM as part of a scenario analysis tool for strategic supply network design and analysis. The simulation results show that performance of a system as a whole deteriorates when there is a step-change in the life-cycle demand. While restriction in production capacity does not significantly impact the bullwhip effect, it increases the net stock amplification significantly for the supply chain setting under consideration. Furthermore, a number of important managerial insights are presented based on sensitivity analysis of interaction effect of capacity constraints with other supply chain parameters.     

基于SD的牛鞭效应建模与仿真分析

通过建立一个三级供应链系统的SD模型,研究探讨牛鞭效应的产生机制及弱化途径。仿真结果表明,牛鞭效应很大程度上是供应链体系自身的特点和结构造成的,而采用具有信息共享机制的VMI订货模式可以大大弱化牛鞭效应,能够有效降低供应链各节点的库存成本。     

Structuring and contracting in competing supply chains

This paper considers two competing supply chains, each with multiple upstream suppliers producing complementary products and selling to a single buyer (e.g., assembler or retailer), who then sells the finished assembled product to a market that involves both demand uncertainty and competition. Our main research questions focus on what supply chain structure (integration vs. decentralization) and which contracting strategy a business should choose. We find that supply chains that decentralize perform better under strong market competition (i.e., high degree of product substitution between supply chains). However, when a large number of suppliers exist, supply chains that integrate perform better. When decentralized structures are used for both supply chains, a consignment with revenue sharing contract generally outperforms a wholesale price contract from the downstream retailer's point of view. Interestingly, for a supplier, a wholesale price contract, which pushes all demand risks to the downstream retailer, might not be preferred. For the entire supply chain, one contract strategy can outperform another depending on the degree of competition, the cost share of the buyer, and the number of suppliers.     

Robust supply chain management

Faced with uncertainty, researchers have explored concepts such as robustness, flexibility, information structure, options, and market power for supply chain management. Despite many influential findings, such as the presence of the bullwhip effect and channel power, the literature in supply chain management is a bit confusing with regard to these concepts, including how they are related to each other. In light of this, we discuss the meaning of the terms in a supply chain management context. We indicate what questions are at stake and some pitfalls to be aware of if the phenomenon we are concerned about is affected by strategic players. This paper is modelling focused.     

Variance amplification and the golden ratio in production and inventory control

A discrete linear control theory model of a generic model of a replenishment rule is presented. The replenishment rule, which we term a “Deziel Eilon—automatic pipeline, inventory and order-based production control system”, is guaranteed to be stable. From a z-transform model of the policy, an analytical expression for bullwhip is derived that is directly equivalent to the common statistical measure often used in simulation, statistical and empirical studies to quantify the bullwhip effect. This analytical expression clearly shows that we can reduce bullwhip by taking a fraction of the error between the target and actual inventory and pipeline (or work in progress (WIP) or “orders placed but not yet received”) positions. This is in contrast to the common situation where ordering policies account for all of the error every time an order is placed. Furthermore, increasing the average age of the forecast reduces bullwhip, as does reducing the production/distribution lead-time. We then derive an analytical expression for inventory variance using the same procedure to identify the closed form bullwhip expression.We assume that a suitable objective function is linearly related to the bullwhip and inventory variance amplification ratios and then optimise the PIC system for different weightings of order rate and inventory level variance. We highlight two forms of the objective function, one where “the golden ratio” can be used to determine the optimal gain in the inventory and WIP feedback loop and another that allows the complete range of possible solutions to be visualised. It is interesting that the golden ratio, which commonly describes the optimum behaviour in the natural world, also describes the optimal feedback gain in a production and inventory control system.     

The food system transformation in developing countries: A disaggregate demand analysis for fruits and vegetables in Vietnam

Food systems in developing countries are currently undergoing a rapid transformation towards high-value products and modern supply chains. While supply side aspects of this transformation have been analyzed previously, issues of consumer demand have received much less attention. This article analyses demand patterns for fresh fruits and vegetables in Vietnam, using household survey data and a demand systems approach. Demand for products from modern supply chains – particularly supermarkets and non-traditional imports – is highly income elastic, and the income effect is stronger than the impact of prices and supermarket penetration. This highlights the importance of considering demand side aspects when projecting future trends. Our results imply a continued restructuring of the food sector in the further process of economic development.     

Designing an electronic auction market for complex ‘smart parts’ logistics: Options based on LeBaron's computational stock market

Modern technologies, such as RFID, offer never-before seen learning abilities to parts moving in supply chains. Logistics systems may be understood as complex adaptive logistics systems (CALS). They also may be conceived as electronic auction markets as ‘smart parts’ bid for the best routing and pricing from transportation firms. To ensure the world-wide functionality and efficiency of CALS transportation markets, we suggest the utility of an agent-based computational market design based on Blake LeBaron's stock-market model. Given that parts may be more or less smart, markets more or less complex, and self-organizing CALS systems probabilistically subject to the bullwhip effect, we suggest nine different computational CALS market-design options, offering more adaptivity to unexpected environmental contingencies.     

Sourcing in the global aerospace supply chain using online reverse auctions

This article discusses the use of online reverse auctions to source engineered components in global aerospace supply chains using online reverse auctions and examines the specific case where a long-established U.S. economic cluster supporting large tier-one aerospace companies must compete against globally distributed sources of supply favored by their customers due to unit price savings, principally the result of lower wages. The article also examines if global sourcing practices based on power-based bargaining is an intelligent or effective solution to market pressure demanding lower prices, or whether collaborative problem solving and the creation of knowledge-sharing networks offers greater potential for cost savings and improved long-term supply chain competitiveness. Key factors that contributed to the recent failure of global sourcing initiatives using online reverse auctions are presented. Findings can be generalized to other industries that use online reverse auctions for globally sourcing engineered components that rely on networks of supporting service suppliers to create finished goods.     

How should you stabilise your supply chains?

This case based research paper examines the stabilisation strategies used within seven supply chains and presents a framework to help practitioners stabilise their chains. The findings show that organisations should first select a cushioning strategy and then reduce demand uncertainty to lower the level of cushion held. However, they need to recognise that other organisations within the supply chain are making similar decisions and the whole supply chain needs to be stabilised. Despite this, businesses seem to only share information about their demand uncertainty-reducing mechanisms and not their cushioning strategies. This means that companies often make decisions in isolation of each other, which can then destabilise the chain.     

Efficient versus Responsive Supply Chain Choice: An Empirical Examination of Influential Factors

Contemporary strategies in operations management suggest that successful firms align supply chain assets with product demand characteristics in order to exploit the profit potential of product lines fully. However, observation suggests that supply chain assets often are longer lived than product line decisions. This suggests that alignment between supply chain assets and demand characteristics is most likely to occur at the time of initial market entry. This article examines the association between product demand characteristics and the initial investment in a supply chain at the time of market entry. We characterize supply chains as responsive or efficient. A responsive supply chain is distinguished by short production lead‐times, low set‐up costs, and small batch sizes that allow the responsive firm to adapt quickly to market demand, but often at a higher unit cost. An efficient supply chain is distinguished by longer production lead‐times, high set‐up costs, and larger batch sizes that allow the efficient firm to produce at a low unit cost, but often at the expense of market responsiveness. We hypothesize that a firm's choice of responsive supply chain will be associated with lower industry growth rates, higher contribution margins, higher product variety, and higher demand or technological uncertainty. We further hypothesize that interactions among these variables either can reinforce or can temper the main effects. We report that lower industry growth rates are associated with responsive market entry, but this effect is offset if growth occurs during periods of high variety and high demand uncertainty. We report that higher contribution margins are associated with responsive market entry and that this effect is more pronounced when occurring with periods of high variety. Finally, we report that responsive market entry also is correlated positively with higher technological demand uncertainty. These results are found using data from the North American mountain bike industry.     

The Impact of Recent Gas Market Developments on Long-Term Projections for Global Gas Supply

Production from unconventional resources, increases in upstream development costs and sluggish demand growth have significantly impacted the global natural gas market in the recent past; and will likely continue to do so during the next decade. Taking these developments into account, we provide a projection of global natural gas supply until 2030 applying the MAGELAN world gas model by the Institute of Energy Economics at the University of Cologne (EWI). Apart from presenting the results of this simulation, the focus of this paper is thereby on the effects of recent supply, midstream and demand side trends on future gas supply compared to earlier studies and projections. While lower demand growth generally leads to relatively less international gas trade, pipeline exports are affected more strongly than trade in liquefied natural gas. In terms of gas output, this volume effect is found to mainly affect high cost gas producers at the upper end of the supply curve. Exports of suppliers with lower production costs and abundant reserves actually benefit.     

A holistic network model for supply chain analysis

Supply chain researchers are experiencing a conceptual and analytical paradox. They are asked to move beyond dyadic analyses and investigate larger network effects with only a limited analytical toolkit. This research proposes the use of bilinear mixed-modeling to holistically analyze supply chain phenomena. Through this approach, researchers are able to account for multiple supply chain relationships, higher-order dependencies among member firms, and simultaneously evaluate covariates from buyer and seller perspectives. The model is validated through the lens of a pervasive supply chain problem commonly referred to as the bullwhip effect. A sample of firms from the US apparel industry in 2004 is analyzed and then the findings are confirmed using data from 2005. In addition to validating the model through the presence of the bullwhip effect, the bilinear model illuminates variables such as advertising, price deals, inventory turnover, and inventory backlogs that exacerbate or diminish inventory differences between firms in a supply chain. The results extend research on supply networks and supply efficiency to a more holistic level and show that higher-order dependencies are important drivers of supply chain phenomena.     

A big data driven framework for demand-driven forecasting with effects of marketing-mix variables

This study aims to investigate the contributions of promotional marketing activities, historical demand and other factors to predict, and develop a big data-driven fuzzy classifier-based framework, also called “demand-driven forecasting,” that can shape, sense and respond to real customer demands. The availability of timely information about future customer needs is a key success factor for any business. For profit maximization, manufacturers want to sense demand signals and shape future demands using price, sales, promotion and others economic factors so that they can fulfil customer's orders immediately. However, most demand forecasting systems offer limited insight to manufacturers as they fail to capture contemporary market trends, product seasonality and the impact of forecasting on the magnitude of the bullwhip effect. This paper aims to improve the accuracy of demand forecasts. In order to achieve this, a back-propagation neural network-based model is trained by fuzzy inputs and compared with benchmark forecasting methods on a time series data, by using historical demand and sales data in combination with advertising effectiveness, expenditure, promotions, and marketing events data. A statistical analysis is conducted, and the experiments show that the method used in the proposed framework outperforms in optimality, efficiency and other statistical metrics. Finally, some invaluable insights for managers are presented to improve the forecast accuracy of fuzzy neural networks, develop marketing plans for products and discuss their implications in several fields.     

下游行业需求不旺 炼焦煤市场难有起色——来自2012年(第二届)国际炼焦煤资源与市场高峰论坛的报道

介绍了国际炼焦煤资源与市场需求的最新状况,就宏观能源战略、钢铁行业焦煤需求、国际炼焦煤供给、中国炼焦煤供给等相关问题进行了分析和探讨。认为,未来几年我国钢材需求增速放缓,炼焦煤整体供过于求。并建议作为钢铁行业的上游,炼焦煤生产企业应积极寻求精细化发展,控制产能保价格,坚持煤炭市场化改革。     

Quality certification vs. product traceability: Consumer preferences for informational attributes of pork in Georgia

Consumer willingness-to-pay for informational attributes of food products is important information for food producers and supply chain participants and policy makers. We examine consumer demand in the pork sector of the Republic of Georgia. Results of conditional and mixed logit estimation, conducted on choice experiment data, reveal that Georgian consumers treat quality certification and product traceability attributes as substitutes. We also find that producers and other supply chain participants should be concerned primarily with maintaining the appearance of pork products. Retailer specific factors such as location and type of outlet can also substitute for product traceability. Store location and product appearance, however, are complementary attributes. In light of the recent turbulence in Georgia these consideration may be of paramount importance as participants in the supply chain seek to rebuild damaged infrastructure.     

Moderating the impact of global sourcing on inventories through supply chain management

In recent years, companies have paid growing attention to supply chain management at a global level. With regard to the upstream part of the supply chain, the need for better suppliers, the research into specific competences and concerns related to international competition have forced companies to improve their ability to cope with suppliers located in different countries around the world. The literature suggests that the geographical distance of suppliers should create higher inventory levels primarily because of longer and more uncertain lead times. However, as this paper aims to demonstrate, companies can limit this effect by means of specific investments in the supply chain and in their relationships with suppliers. The empirical analysis is based on data from the last edition of the International Manufacturing Strategy Survey (IMSS). The results show that companies performing global sourcing have invested in supply chain management (SCM) and that this has been helpful in keeping their inventories under control.