Optimization of production allocation and transportation of customer orders for a leading forest products company

A leading manufacturer of forest products with several production facilities located in geographical proximity to each other has recently acquired a number of new production plants in other regions/countries to increase its production capacity and expand its national and international markets. With the addition of this new capacity, the company wanted to know how to best allocate customer orders to its various mills to minimize the total cost of production and transportation. We developed mixed-integer programming models to jointly optimize production allocation and transportation of customer orders on a weekly basis. The models were run with real order files and the test results indicated the potential for significant cost savings over the company’s current practices. The company further customized the models, integrated them into their IT system and implemented them successfully. Besides the actual cost savings for the company, the whole process from the initial step of analyzing the problem, to developing, testing, customizing, integrating and finally implementing the models provided enhanced intelligence to sales staff.     

币值低估下对外贸易对物价水平的影响

从货币数量方程出发,运用汇率理论与对外贸易理论,主要讨论了币值低估时,对外贸易对经济体内物价水平的影响.在外贸情况一定时,经济体内物价水平与币值低估程度正相关;当币值低估程度确定,进出口比例与外贸规模也会对经济体内的通胀大小产生影响,具体表现为:外贸顺差越大,通胀越严重;但贸易逆差时,仍然有可能出现通胀;而若要追求贸易平衡的目标,则外贸规模越大,通胀越严重.同时,一国的币值低估还通过对外贸易对他国的物价水平产生影响.     

Designing optimal global supply chains at Dow AgroSciences

The design of the underlying supply chain network can have a tremendous impact on the profitability, manageability, and level of risk of a global supply chain. Taxes, duties, and tariffs vary from country to country as well as trading bloc to trading bloc and can consume as much as 10% of the revenues of certain products. In the highly regulated business environment of agricultural chemicals, the country of origin of an active ingredient can determine where the final product can be marketed and the amount of taxes and duties applied to the product, making it necessary to trace all batches of product through many layers of the supply chain to their sources. This article presents a mixed integer linear programming model in use at Dow AgroSciences LLC that simultaneously optimizes the network design underlying global supply chains and the monthly production and shipping schedules for maximum profitability. This work contributes to the supply chain design literature by demonstrating a novel method of tracing products to their source for inventory valuation, taxation, and duty computation in a production environment where the products change into other products as they pass through nodes in the network. It also demonstrates an iterative scheme for determining unit fixed costs for fixed cost allocation for the same purposes. Finally, it provides a case study of a supply chain design initiative in a global enterprise.     

Transnational remanufacturing decisions under carbon taxes and tariffs

Considering the influence of carbon taxes and tariffs on transnational closed-loop supply chains, this paper establishes three remanufacturing modes of an original equipment manufacturer (OEM) in an exporting country. In one remanufacturing mode, the OEM conducts remanufacturing itself, and in the other two modes, the OEM authorizes a retailer in the importing country to engage in remanufacturing. Next, we analyse the optimal pricing and carbon emissions reduction decisions of the OEM and retailer in the different modes and further study how different levels of carbon tax and tariff combinations impact OEM remanufacturing decisions, the social welfare of importing countries and the environment. The results show the following. (1) When the carbon tariff is high, the optimal sales of remanufactured products increase. However, this does not contribute to the continuation of the product system; thus, it is short sighted for the government to hastily set high carbon tariffs to discourage the import of new products to protect domestic enterprises. (2) Carbon tariffs cannot effectively encourage the OEM to invest in emission reduction because carbon tariffs are passed on to consumers in importing countries through price adjustment. However, carbon tax may be an indirect factor affecting the OEM's willingness to invest in emission reduction. (3) The OEM favours allowing the retailer to remanufacture when the carbon emissions of the remanufactured products are similar to those of new products. Co-investment in emission reduction has the potential to align the profit maximization of the OEM with the social welfare maximization of the importing country. (4) It is not profitable for the importing government to set high carbon tariffs to protect its own enterprises.     

汇率变动对进出口影响的实证分析

本文研究了汇率变动对中国进出口的影响,在间接标价法下对论文中所用到的汇率贬值改善国际收支的三个必要条件给出了结论和证明(弹性法);在经济理论及经验研究的基础上,建立了论文中所需要的所有模型并且根据模型对相关经济问题利用现代计量经济学方法进行了实证研究.通过实证研究我们得到的结论是:我国满足汇率贬值改善国际收支的必要条件;出口增加有助于GDP的增长,进口增加对GDP的影响是反向的且随着进口增加这种影响逐渐减弱最终趋于零.     

Supply chain design considering economies of scale and transport frequencies

In this paper we consider a 3-echelon, multi-product supply chain design model with economies of scale in transport and warehousing that explicitly takes transport frequencies into consideration. Our model simultaneously optimizes locations and sizes of tank farms, material flows, and transport frequencies within the network. We consider all relevant costs: product cost, transport cost, tank rental cost, tank throughput cost, and inventory cost. The problem is based on a real-life example from a chemical company. We show that considering economies of scale and transport frequencies in the design stage is crucial and failing to do so can lead to substantially higher costs than optimal. We solve a wide variety of problems with branch-and-bound and with the efficient solution heuristics based on iterative linearization techniques we develop. We show that the heuristics are superior to the standard branch-and-bound technique for large problems like the one of the chemical company that motivated our research.     

竞争市场下考虑再制造产品售后服务的供应链运营策略

在同时生产新产品和再制造产品的原始制造企业(企业1)与生产具有替代性产品的企业(企业2)构成竞争关系下的供应链系统中,探讨供应链在不同售后服务策略下供应链的运营策略,分析在竞争市场下供应链定价策略和再制造产品的售后服务对定价策略及供应链中各企业利润的影响。揭示再制造产品售后服务对定价策略和供应链各企业最优利润的影响。得到如下主要研究结论:(1)当制造企业为再制造产品提供售后服务时,再制造产品销售量增加,新产品和竞争替代产品销售量降低;有趣的是新产品和再制造产品的市场零售价格同时增加,竞争替代产品的市场零售价格降低。(2)制造企业为再制造产品提供售后服务时的利润总是大于没有售后服务时的利润,且不受单位产品生产成本影响。同时当单位产品生产成本较高时,制造企业为再制造产品提供售后服务策略会带来竞争对手企业利润增加。这些结论对具有再制造产品供应链如何提供再制造产品售后服务具有一定指导作用和管理启示。     

Analysis of an industrial component commonality problem

We discuss a case study of an industrial production-marketing coordination problem involving component commonality. For the product line considered, the strategic goal of the company is to move from the current low volume market to a high volume market. The marketing department believes that this can be achieved by substantially lowering the end products’ prices. However, this requires a product redesign to lower production costs in order to maintain profit margins. The redesign decision involves grouping end products into families. All products within one family use the same version of some components. This paper fits in the stream of recent literature on component commonality where the focus has shifted from inventory cost savings to production and development cost savings. Further, we consider both costs and revenues, leading to a profit maximization approach. The price elasticity of demand determines the relationship between the price level and number of units sold. Consequently, we integrate information from different functional areas such as production, marketing and accounting. We formulate the problem as a net-present-value investment decision. We propose a mixed integer nonlinear optimization model to find the optimal commonality decision. The recommendation based on our analysis has been implemented in the company. In addition, the application allows us to experimentally validate some claims made in the literature and obtain managerial insights into the trade-offs.     

On the optimization of supply chain networking decisions

Companies strive to position themselves to maximize the value they add to the supply chains in which they are embedded. This raises strategic questions such as: Which durable resources should be developed to enhance current core competencies? Which activities should be externalized and to which potential partner should they be given? Which internal activities should be preserved and developed? How should the resources of the enterprise be allocated to activities? The aim of this paper is to propose a mathematical programming model of the extended enterprise which can be used to investigate this type of strategic networking issues. A number of general network modeling constructs are first proposed. A model to optimize the supply chain structure under specific assumptions on the nature of production, cost and value functions in typical production/distribution companies is then derived. A heuristic to obtain solutions from the model is also presented. Finally, an example based on a refrigerator company is used to illustrate the usefulness of the approach.     

Cooperative game theory approach to allocating benefits of horizontal cooperation

Logistics costs in general, and transportation costs in particular, represent a large fraction of the operating costs of many companies. One way to try to reduce these costs is through horizontal cooperation among shippers. Thus, when the transportation needs of two or more companies are merged, their collective transportation requirements can be met at lower cost. The attainable cost savings are due to economies of scale, which translate into cheaper rates due to increased negotiation power, use of larger vehicles and bundling of shipments. In this paper, a linear model is presented and used to study the cost savings that different companies may achieve when they merge their transportation requirements. On the one hand, solving this optimization model for different collaboration scenarios allows testing and quantifying the synergies among different potential partners, thus identifying the most profitable collaboration opportunities. On the other, the problem of allocating the joint cost savings of the cooperation is tackled using cooperative game theory. The proposed approach is illustrated with an example in which different cooperative game solution concepts are compared. Extensive numerical experiments have also been carried out to gain insight into the properties of the corresponding cost savings game and the behavior of the different solution concepts.     

美国经济冲击对东亚经济波动的传导:基于面板logit模型的实证分析

美国经济冲击会通过具体渠道进行传导,影响东亚地区的经济波动.具体来看,与美国的双边进口贸易渠道和FDI渠道的传导会增加东亚地区经济波动概率,并且在控制国内经济规模后,边际效应进一步提高;与美国的双边出口贸易渠道和汇率渠道的传导反而会降低东亚地区经济波动的概率;并且传导效应在不同经济发展程度的国家呈现出明显的差异,发展中经济体受美国经济冲击的影响较大.     

Global plant capacity and product allocation with pricing decisions

Trade-offs in global manufacturing decisions involve markets, resource costs, trade-barriers, currency exchange rates, joint ventures and investments. We develop a model that optimizes plant investment decisions, while ensuring that the plant investment overhead is optimally absorbed by products produced from that plant. The model also, simultaneously, determines prices by products and countries. The special structure of the model is exploited to construct a fast solution procedure. The model is used to study the implications of labor cost, transportation cost, demand, and import tariff on production quantities, investment, and overhead absorption pattern. Implications of changes in other global parameters such as local-content rule, local taxes, size of the market in a country, and long-term exchange rates are also studied.     

Optimal pricing,EOL (end of life) warranty,and spare parts manufacturing strategy amid product transition

We study firm’s strategy to determine its product price and warranty period, and plan the spare parts manufacturing so as to maximize its profit and at the same time to fulfill its commitment to providing the customer with the key part continuously over the relevant decision time horizon, i.e., the product’s life cycle plus its EOL service (warranty) period. To examine the research question, we develop and solve a two-stage optimal control theory model. From the numerical analysis, we infer as follows. It is not always true that the longer the EOL warranty period, the better for the company’s profitability, implying there exists an optimal EOL warranty period that balances all the relevant forces like market demand and cost structures. The relationship between optimal EOL warranty period and failure rate (defect rate) is concave: when the defect rate is moderate, the company has to increase its EOL warranty period as the defect rate increases so as to compensate for the deteriorating quality; but, when the defect rate is beyond a threshold level, the company needs to curtail its EOL warranty commitment as the defect rate increases in order to avoid excessive cost to service the failed parts. By depicting key dynamics in this managerial problem, this paper sheds light on how to make decision for optimal pricing and warranty when the product life cycle is finite and the company is obliged to provide after-sales services to customers for an extended period of time after the current product is no longer produced.     

How big is too big? Trading off the economies of scale of larger telecommunications network elements against the risk of larger outages

This paper builds a probabilistic model to analyze the risk–reward tradeoffs that larger telecommunications network elements present. Larger machines offer rewards in the form of cost savings due to economies of scale. But large machines are riskier because they affect more customers when they fail. Our model translates the risk of outages into dollar costs, which are random variables. This step enables us to combine the deployment cost and outage cost into a total cost. Once we express the decision makers’ preferences via a utility function, we can find the machine size that minimizes the total cost’s expected utility, thereby achieving an optimal tradeoff between reward and risk. The expected utility answers the question “how big is too big?”.     

基于产品生命周期的闭环供应链定价和协调策略研究

研究产品生命周期条件下一个制造商、一个零售商组成的闭环供应链的定价和协调策略:制造商第一周期只生产新品,从第二周期开始生产再制造品,并负责回收。建立了两周期、多周期和无限周期下的分散决策模型和多周期下的集中决策模型,得到最优定价和生产策略。结果表明:两周期中,制造商和零售商应根据不同的成本节约额制定不同的批发价、零售价和生产量。多周期中,当成本节约额比较小时,除第一和最后一个周期外,制造商和零售商应采取相同的定价和生产策略;当成本节约额比较大时,除第一和最后两个周期外,制造商和零售商应采取相同的定价和生产策略。无限周期中,除第一周期以外,制造商和零售商都应该采取相同的定价和生产策略。在有限周期情况下,制造商和零售商应通过在前期制定比较低的批发价和零售价,以提高生产量和销售量,使得后期的回收量增大,达到降低成本的目的。通过引入收益共享契约制定合适的批发价和销售收入及再制造收益共享比率可以协调整个闭环供应链。算例验证了上述结论。     

Impact of taxation on international transfer pricing and offshoring decisions

A multinational company may move production to a foreign country to take advantage of low manufacturing cost, and/or experience tax savings. Transfer prices play an important and strategic role on income shifting by multinational companies. In this paper, we construct a framework for optimal decision making in global supply chains with uncertain and price-dependent demand, propose methods to improve global supply chain parties’ performance, and explore schemes to integrate global supply chains. The optimal pricing and offshoring decisions are investigated for different situations where the low foreign production cost and low foreign tax rate exist or only one of them is available. The case of low foreign tax rate without the advantage of low foreign production cost provides the most interesting findings that partial offshoring dominates when a certain threshold is met. In addition, the double marginalization is examined in decentralized global supply chains similar to the mechanism in newsvendor problems. Due to the existence of the tax jurisdiction, the double marginalization cannot be completely eliminated by coordinating schemes. Finally, the traditional buy back contract is found to be unable to coordinate global supply chains, while a modified sales sharing contract can improve the performance of the global supply chain.     

外汇储备规模与多元变量弹性系数的实证研究

中国外汇储备近几年的迅速增长引发了关于中国外汇储备规模是否适度的广泛讨论。本文从需求的角度,运用计量经济学的多元线性回归的方法,建立中国外汇储备与平均进口倾向、进口和国际收支三变量的双对数模型,通过计算并通过相关检验得到外汇储备与相关变量的弹性系数。为预测和制定相关政策提供依据。     

An interval portfolio selection problem based on regret function

Recent mergers in the banking industry have often generated disappointing shareholder returns. Delays in implementing potential operating savings and realizing benefits of scale economies may be one reason these mergers have disappointing returns. Using data envelopment analysis (DEA), we analyze a 200-branch network formed in a merger of four banks. The operating efficiency of each branch is benchmarked against “best-practice” branches in the combined merged bank as well as “best practice” branches within each pre-merger bank. This analysis identified opportunities to reduce branch operating costs by 22 percent for the entire merged bank. In contrast, the cost savings opportunity is under seven percent when analyzed within each pre-merger bank.These findings suggest benchmarking across the entire merged bank to identify the best practices bank-wide can generate added savings. However, in this bank merger, these merger benefits were not realized until four years after the merger. Interviews with key players in the merged bank indicate that the bank deferred realizing these benefits because of political pressures, personnel integration issues, system integration issues, and financial components of the merger such as restructuring reserves and the purchase price. These causes suggest areas where shareholders can and should demand more rapid improvement in performance of bank mergers and areas for future corporate merger research.     

Optimization-based Distribution Planning for Consumer Electronic Items

This paper describes the application of network modeling and optimization for short-term distribution planning in an Indian electronica firm. The company has three production centres, each comprising several factories. Each day, it ships finished product from the three production centres to 23 distribution centres (namely, its branches and sub-branches) spread all over the country. The present problem may be stated as: given the planned production quantity at each production centre and the estimated demand at each distribution centre for each week of a given month, specify the quantities to be dispatched from each production centre to the various distribution centres in each week of the month. The problem is modelled as a multi-period, minimum-cost, network flow model for each product item. The paper also discusses the implementation and actual use of the model for monthly distribution planning at the company.     

固定经营期下基于运行绩效的PPP项目服务价格形成机制研究

本文研究PPP项目价格形成机制、补偿机制及其社会效率。首先,分析了招投标制度下固定经营期PPP项目服务价格形成机制及其不足。其次,基于成本与运行绩效的PPP项目定价规制及可行性缺口补贴思想,建立模型分析实施机构可观察PPP项目服务成本时的定价水平和可行性缺口补贴标准;当实施机构无法准确掌握项目公司的运行成本时,通过制度设计诱导社会投资者上报真实的运行成本和运行绩效以获得最大净现值。分析表明,当PPP项目服务需求弹性较大同时有可行性缺口补贴政策时,政府进行价格规制时项目净现值高于不规制时的净现值。文章通过实例验证了成本信息是否可观察两种情形下PPP项目的服务价格水平、运行绩效、项目投资净现值及消费者剩余。为了避免PPP项目运行绩效下降和社会福利损失,政府应建立科学的监督激励机制,依据PPP项目服务成本与运行绩效的信息确定固定特许经营期下项目服务价格和可行性缺口补贴额度。