An optimization model for line planning and timetabling in automated urban metro subway networks. A case study

In this paper we present a Mixed Integer Linear Programming model that we developed as part of a pilot study requested by the R&D company Metrolab® in order to design tools for finding solutions for line planning and timetable situations in automated urban metro subway networks. Our model incorporates important factors in public transportation systems from both, a cost-oriented and a passenger-oriented perspective, as time-dependent demands, interchange stations, short-turns and technical features of the trains in use. The incoming flows of passengers are modeled by means of piecewise linear demand functions which are parameterized in terms of arrival rates and bulk arrivals. Decisions about frequencies, train capacities, short-turning and timetables for a given planning horizon are jointly integrated to be optimized in our model. Finally, a novel matheuristic approach is proposed to solve the problem. The results of extensive computational experiments are reported to show its applicability and effectiveness to handle real-world subway networks.     

基于TPCBoost模型的新型交通服务定价研究—以纽约网约车为实例

当前新型交通服务定价一般基于单个特征为前提进行定价探讨,缺乏对不同特征及总体定价的宏观研究。本文集成优化多个CART树得到TPCBoost模型,同时利用纽约市网约车搭乘数据为基础,训练、测试TPCBoost模型,并利用模型分析不同特征的关系及对定价的影响,不仅验证了模型具有更强的鲁棒性及稳定性,同时发现：(1)特征非线性影响定价,短距离、短时间、少乘客时定价稳定,长距离、长时间、多乘客时定价波动剧烈;(2)当特定搭乘距离与特定搭乘时间进行组合时,会出现定价敏感期,在定价敏感期时市场竞争白热化,此时特定搭乘时间抑制定价上涨;(3)搭乘人数不直接影响定价,但与其他特征进行组合时会间接影响定价;(4)搭乘距离正影响定价,但在定价敏感期时不直接影响定价;(5)每日搭乘时间周期性影响定价,特别地,每日会出现若干定价转折时间点,其中波峰定价时间点一般多于波谷定价时间点。本文提出的TPCBoost模型经实际数据验证符合定价规律,可以为营运公司、监管部门及乘客的交通决策提供有益参考。     

Integrated supply,production and distribution scheduling under disruption risks

This paper presents a bi-objective stochastic mixed integer programming approach for a joint selection of suppliers and scheduling of production and distribution in a multi-echelon supply chain subject to local and regional disruption risks. Two conflicting problem objectives are minimization of cost and maximization of service level. The three shipping methods are considered for distribution of products: batch shipping with a single shipment of different customer orders, batch shipping with multiple shipments of different customer orders and individual shipping of each customer order immediately after its completion. The stochastic combinatorial optimization problem is formulated as a time-indexed mixed integer program with the weighted-sum aggregation of the two objective functions. The supply portfolio is determined by binary selection and fractional allocation variables while time-indexed assignment variables determine the production and distribution schedules. The problem formulation incorporates supply–production, production–distribution and supply–distribution coordinating constraints to efficiently coordinate supply, production and distribution schedules. Numerical examples modelled after an electronics supply chain and computational results are presented and some managerial insights are reported. The findings indicate that for all shipping methods, the service-oriented supply portfolio is more diversified than the cost-oriented portfolio and the more cost-oriented decision-making, the more delayed the expected supply, production and distribution schedules.     

具有网络外部性的扩展Hotelling模型

将网络外部性引入线性运输成本下的Hotelling模型,研究了两家网络产品厂商首先选址,然后进行价格竞争的两阶段完全信息动态博弈问题,得到了厂商价格竞争均衡的存在性条件,推广了一般Hotelling模型的结论.由于网络外部性的存在,消费者效用是相互依赖的.网络产品的市场份额既是消费者选择的结果,又是消费者选择的依据.文章将交通流量分配技术和无穷维变分方法相结合,建立了刻画网络产品市场划分的模型——无穷维变分不等式,并研究了市场划分的存在性和唯一性问题.最后假定厂商定位在两端,分析了产品的网络外部性特征及单位运输成本对两个厂商竞争均衡情况的影响.     

Optimal Policies for Perishable Products When Transportation to Export Market Is Disrupted

We consider a problem where a firm produces a variety of fresh products to supply two markets: an export market and a local market. A public transportation service is utilized to deliver the products to the export market, which is cheap, but its schedule is often disrupted severely. Each time this happens, the firm faces the following questions. (i) For a product that has been finished and is waiting for delivery to the export market, should it continue to wait, at an increasing risk of decay, and when should the waiting be terminated and the product be put to the local market? (ii) For a product that has not been finished, should its processing be postponed, so as to reduce the loss from decay after its completion? (iii) What is the best sequence to process the remaining products, according to the information available? We develop, in this study, a model to address these and other related questions. We find optimal policies that minimize the total expected loss in both the make‐to‐order and make‐to‐stock production systems, respectively. For each finished product, we reveal relationships among the desirable waiting time, the price at the local market, and the decaying cost. For unfinished products, we find the optimal start times and processing sequence. Numerical experiments are also conducted to evaluate the optimal policies.     

Zur ?Pr?ferenzabh?ngigkeit“ von Unternehmenswerten bei pers?nlicher Besteuerung

Large parts of firm valuation literature are concerned with the calculation of the so-called ??value of debt tax shields??, i.e., the market value surplus of partly debt-financed firms over operationally identical unlevered firms. In this article, I focus on those papers which employ simple duplication techniques according to Modigliani and Miller (1958). Given asymmetric tax treatment of investments and credits, this procedure is not convincing: Since the results of computations lack uniqueness, the value of levered firms is attributed to be a matter of preferences. In contrast, I try a more profound consideration of market conditions. The results are as follows: The mentioned valuation concept is not compatible with asymmetric taxation, therefore inconsistent outcomes are possible. At most, pricing bounds can be fixed. Proper market-driven valuation by super-replication is more complex, but independent of risk preferences.     

Corporate strategies for political action

Discussions of the firm's relationships with its environment have usually concluded that the firm should make adaptive decisions to non-market areas, and proactive or strategic decisions in market areas. Predicating strategic responses upon the differences between market and non-market relationships is inappropriate and misleading, reduces the capacity of the firm to respond effectively to its environment, and distorts the process of environmental scanning. When the firm's relationships with its environment are examined as inter-organizational relationships, market and non-market relationships are structurally similar, and the same types of strategic responses can be selected for both areas. The strategic responses available to the firm in inter-organizational terms are: adaptation; pre-emption, co-optation; interpenetration; conflict and withdrawal. These processes and choices are structurally similar to traditional market related strategic options and can be used to respond to market and non-market factors. The manager scans the environment not only to identify opportunities for adaptation, but to identify groups which affect the integrity of the firm, the processes for interaction, the character of relationships, and occasions for strategic choice. The strategic decision process under a framework of inter-organizational transactions is illustrated by the cases of Sun Life Insurance Co., and the pulp and paper industry in Quebec.     

A model for reverse logistics entry by third-party providers

Reverse logistics has become an important entity in the US economy. Nonetheless, many companies are not capable of or are unwilling to enter the reverse logistics market. Such reluctance appears to be attributed to lack of knowledge of reverse logistics. This paper reviews current industry practices in reverse logistics. Specifically, we examine the issues and processes that an organization has to address to engage in the reverse logistics business. A reverse logistics decision-making model is developed to guide the process of examining the feasibility of implementing reverse logistics in third-party providers such as transportation companies. The purpose of this model is to help those companies who would like to pursue reverse logistics as a new market. A field study was conducted with a larger US transportation company to validate the proposed model.     

非均衡交通规划初探

传统交通规划以微观经济学瓦尔拉斯均衡原理作为理论基础 ,交通规划是针对市场均衡点进行展开的 ,不涉及非均衡区域 .实际上 ,均衡状态是一种特殊的非均衡 ,在一定的市场条件下才能实现 ,即使实现了 ,也是暂时的 ,它不能代表真实的市场情况 .鉴于运输市场非均衡的普遍存在性 ,本文根据非均衡理论及相关研究成果 ,提出了非均衡交通规划的思想 .通过对市场调控机制的分析 ,研究了运输市场非均衡的存在性 ;利用变分不等式对均衡与非均衡的统一性进行了等价描述 .提出了非均衡交通需求预测的思想 ,并将非均衡价格——数量调节行为原理引入到传统的用户路线选择行为之中     

基于β系数优化的动态投资组合策略研究

本文提出一种股票动态投资组合策略，首先通过上升和下降贝塔来优选行业，然后在选择的行业中构造股票投资组合。对于股票投资组合，利用均值方差投资组合模型作为内核，通过引入参考时间窗口和持有期限窗口两个外生参数构建动态的均值-方差模型，并实证检验了模型的可行性。然后再经过多项业绩评价指标对比分析得出动态投资组合策略的收益明显优于被动投资策略，这种动态投资组合策略能够获得部分超额收益并且具有更好的可靠性。本研究为投资者提供了一种定量的投资组合管理方法，并从侧面验证了我国股市的非有效性。     

Optimization and Coordination of Fresh Product Supply Chains with Freshness‐Keeping Effort

We consider a supply chain in which a distributor procures from a producer a quantity of a fresh product, which has to undergo a long‐distance transportation to reach the target market. During the transportation process, the distributor has to make an appropriate effort to preserve the freshness of the product, and his success in this respect impacts on both the quality and quantity of the product delivered to the market. The distributor has to determine his order quantity, level of freshness‐keeping effort, and selling price, by taking into account the wholesale price of the producer, the cost of the freshness‐keeping effort, the likely spoilage of the product during transportation, and the possible demand for the product in the market. The producer, on the other hand, has to determine the wholesale price based on its effect on the order quantity of the distributor. We develop a model to study this problem, and characterize each party's optimal decisions in both decentralized and centralized systems. We further develop an incentive scheme to facilitate coordination between the two parties. Computational results are reported to show the effects of freshness‐keeping efforts.     

A COMMENT ON THE COST OF NEW ISSUES OF COMMON STOCK

According to the constant growth model and perceived finance theory, the cost of new external equity exceeds the cost of retained earnings due to flotation costs and underpricing. Carlson and Dietz [1] have recently argued that the constant growth model is operationally inadequate whenever the net proceeds from the issuance of a new share differ from book value. Specifically, they contend that the cost of new external equity is less than the cost of retained earnings whenever the net proceeds from a new share exceed book value. We show that these conclusions stem from an error in interpretation and therefore that the constant growth model is valid regardless of the relationship between market prices and book value.     

Electronic Markets for Truckload Transportation

A wide variety of electronic marketplace formats are used in the Truckload (TL) transportation industry, including combinatorial auctions, private and public exchanges, and electronic catalogs. Combinatorial multi‐attribute auctions are commonly used strategically to populate electronic catalogs, commonly called “routing guides,” with pricing, assignments, and priority logic. Private and public exchanges are used to complement the electronic catalogs in cases where the catalog fails. This paper discusses the TL transportation market, places the procurement of services in the context of electronic marketplace formats, and illustrates how these are currently used.     

CYCLICAL BEHAVIOR OF UNEMPLOYMENT AND THE HELP WANTED INDEX: A CROSS SPECTRAL ANALYSIS

The unemployment rate and the help-wanted index are two frequently used indicators of the state of the labor market. Traditional regression techniques used in the analysis of the relationship between these two indicators and their cyclical behavior with business fluctuations have yielded varying results. Spectral analysis is used in this article to examine the cyclical behavior of the labor market indicators with respect to each other and with respect to a measure of aggregate economic activity in the United States. Very strong relationships are found, lending support to the rationale of using such indicators as labor market proxies. This application of spectral analysis also provides an illustration of the potential fruitfulness of spectral analysis in examining the cyclical relationships between economic time series.     

Adding life cycles to learning curves

The price-oriented experience curve has been extensively utilized as a model in corporate planning. However, managers exercise a greater degree of control over cost than they do over price. The use of the cost-oriented learning curve together with the product life cycle model in strategic planning is explored in this paper. The Ford Motor Company's experience with the Model-T, which was the first mass-produced automobile in the U.S., is used to reinforce the fact that the simultaneous use of the product life cycle and the learning curve would have provided Ford management with better planning information. With this information, Ford could have avoided the subsequent disastrous results which it experienced.     

短生命周期产品供应链中供需双方合作的价值研究

本文研究了只有一个销售商和制造商构成的只有一个短生命周期产品的两层供应链系统,当市场需求和制造商履行订单的时间都是随机变化的,制造商可通过一定方法提前履行订单,建立了制造商与销售商合作与共享信息的一般模型,解析分析了信息共享的价值。解析分析和算例仿真表明,双方合作不但能增加供应链系统的利润,保持利润增加的稳定性,而且还能增加产品对市场的供给量。     

行业特征、市场情绪与收益波动

从行为金融研究的视角,利用源自“上证”(SHSE)A股市场的样本数据,检验了行业特征、市场情绪与收益波动之间的关系。结果表明:在不同的行业特征下,具有类似的投资者行为和风险收益关系,而且均未达到弱式有效;尽管各行业板块之间的收益波动联动效应显著,但市场情绪对不同行业特征的收益波动影响仍有差异性。对管理的启示是,中国证券市场效率还有待进一步提高,利用市场情绪套利时应考虑行业特征。     

考虑社交网络和互联网金融的金融市场超网络均衡研究

社交网络和互联网金融的广泛应用给金融市场发展带来机遇和挑战,金融市场呈现复杂多变、交叉融合的特征,传统的金融市场和监管理论难以适应金融市场发展和风险管理需要。本文从金融网络视角,针对互联网金融发展带来的区别于传统金融的信用风险和操作风险,引入信用惩罚函数和操作风险函数,考虑到加强社交网络关系可提高信息透明度、降低交易成本和交易风险,建立了由资金供给者、互联网金融中介、传统金融中介、资金需求者四种类型金融参与组成的、集成资金流动网络和社交关系网络的金融市场超网络模型,进行金融市场各参与主体的行为分析,建立包括净收益最大化、社交网络关系最大化和风险最小化为目标的多目标决策模型;运用变分不等式将约束条件放松为单边约束,研究包括上述金融市场的均衡条件;最后通过算例的MATLAB仿真验证模型有效性。研究结果表明,考虑与否社交网络关系水平,金融市场的均衡状态不同;社交网络关系水平对互联网金融中介和传统金融中介具有影响作用;为提高市场稳定性和有效性,降低金融风险,互联网金融和传统金融中介需要合作和协同发展。     

Forecasting the market for ships

Product development and market penetration strategy rely on dependable forecasts. Market segmentation is necessary for finding profitable niches. The paper describes macro- forecasts in the maritime sector divided by nine ship types. Balance between supply and demand is calculated with dynamic models. Demand for transportation depends on the development of world trade. Supply of transportation capacity depends on present fleet size, future contracting, scrapping and productivity.     

The five stages of managed care. Strategies for physicians in health care's market revolution

What are the five stages of managed care? From "Can't Spell HMO" to Managed Cooperation, each stage has predictable market events and strategic responses. At every stage, a new set of relationships evolves among the major players, including physicians and hospitals, HMOs and insurers, and employers and government. At each higher level of managed care penetration, the players restructure their relationships as they seek to control their market and their destiny.