Optimizing global thermal coal shipments

Thermal coal is used to produce energy; with changing emissions standards and advents in renewable technology, the thermal coal market has seen significant transformation over the past decade. We develop a mixed-integer optimization problem that seeks to minimize shipment costs while meeting demand for thermal coal, and which respects quality constraints, supply limits, and port capacity; we use this model to analyze the following scenarios: (i) a counterfactual setting in which we compare historical shipping patterns to model results using a 2012 base year; (ii) the explicit effect of Chinese mandates on coal shipments; (iii) the impact on our shipping patterns of reduced Chinese and Indian demand; (iv) the effects of the Baltic Dry Index and oil prices; and (v) a comparison of shipments prior and subsequent to Panama Canal expansion. Our work can be used to inform policy, study responses to variable price and demand scenarios, and provide insight to both coal producers and consumers about the international coal market. For example, removal of mandates set by the Chinese government to fill its own demand decreases coal flows from Northern to Southern China by 56%, which has a spill-over effect on European and American markets; and, expansion of the Panama Canal leads to only modest shipping increases through the canal (6.7%), with more coal originating from Colombia serving Asian demand.     

Tractable Consideration Set Structures for Assortment Optimization and Network Revenue Management

Discrete‐choice models are widely used to model consumer purchase behavior in assortment optimization and revenue management. In many applications, each customer segment is associated with a consideration set that represents the set of products that customers in this segment consider for purchase. The firm has to make a decision on what assortment to offer at each point in time without the ability to identify the customer's segment. A linear program called the Choice‐based Deterministic Linear Program (CDLP) has been proposed to determine these offer sets. Unfortunately, its size grows exponentially in the number of products and it is NP‐hard to solve when the consideration sets of the segments overlap. The Segment‐based Deterministic Concave Program with some additional consistency equalities (SDCP+) is an approximation of CDLP that provides an upper bound on CDLP's optimal objective value. SDCP+ can be solved in a fraction of the time required to solve CDLP and often achieves the same optimal objective value. This raises the question under what conditions can one guarantee equivalence of CDLP and SDCP+. In this study, we obtain a structural result to this end, namely that if the segment consideration sets overlap with a certain tree structure or if they are fully nested, CDLP can be equivalently replaced with SDCP+. We give a number of examples from the literature where this tree structure arises naturally in modeling customer behavior.     

社会网络、 先前经验与创业风险识别

无法识别创业风险是导致创业失败的主要原因之一,如何有效识别并管理创业风险是新创企业健康成长的关键.社会网络能够弥补创业者在识别风险过程中的信息劣势,但既有研究极少探索社会网络是否以及如何影响创业风险识别.为弥补这个研究空白,文章利用信息处理理论为研究框架,构建了创业风险识别模型.具体而言,结构洞和网络强度有利于创业者获取更多、高质量与风险相关的信息,进而识别更多的创业风险;获取信息的数量在网络强度与创业风险识别关系之间发挥完全中介作用;创业者的先前经验正向影响创业风险识别,并对结构洞与获取信息的数量之间关系起调节作用.文章讨论了研究结果的理论贡献与实践启发.     

遗传算法优化神经网络及信用评价研究

研究关于公司神经网络信用评估问题的现状,提出遗传算法辅助网络训练策略(优化后的网络称为进化网络),克服传统网络建模中产生的局部极小缺陷。建立了适合于我国商业企业的信用评分指标体系;然后依据该指标体系建立了基于进化神经网络的信用评估模型;最后,利用样本公司实际指标数据对该模型的评分效果进行了比较研究。     

具有网络外部性的产品兼容性决策分析

通过Stachelberg竞争模型,本文研究了在具有网络外部性的市场中,拥有专有技术的主导厂商对其兼容技术的授权动机问题。并且得到了主导厂商在纵向兼容决策中最优厂商数量的控制的关系。     

不同模型在财务预警实证中的比较研究

研究当前国内外公司财务困境预测问题的现状,寻找一套适合于我国企业的财务状况识别指标体系;然后依据该指标体系采用不同方法建立财务状况预测模型;最后,利用样本公司实际指标数据对各个模型的短期及中期预测效果进行了比较分析与实证研究。     

网络经济下企业兼容性选择与用户锁定策略研究

通过两阶段的Hotelling双头竞争模型,本文将网络外部性与产品兼容性视为导致用户锁定的主要因素,研究了网络外部性以及兼容性所产生的转移成本对消费者的锁定效应,以及网络外部性与兼容性对企业竞争策略的影响。     

Inverse Combinatorial Optimization: A Survey on Problems, Methods, and Results

Given a (combinatorial) optimization problem and a feasible solution to it, the corresponding inverse optimization problem is to find a minimal adjustment of the cost function such that the given solution becomes optimum.Several such problems have been studied in the last twelve years. After formalizing the notion of an inverse problem and its variants, we present various methods for solving them. Then we discuss the problems considered in the literature and the results that have been obtained. Finally, we formulate some open problems.     

网络能力、资源获取与新企业绩效关系实证研究

网络能力是在网络导向驱动下,利用关系技巧和合作技巧进行一系列网络构建和网络管理活动,以实现资源获取目标的能力.在中国转型经济时期,网络能力对于新企业克服资源约束,实现生存和成长具有重要作用.拓展了网络能力的理论内涵,将网络能力划分为网络导向、网络构建和网络管理三个维度,建立了网络能力、资源获取与新创企业绩效关系模型,以322家新企业为样本进行实证分析.研究结果表明,网络导向对网络构建和网络管理具有显著正影响,网络构建和网络管理对知识资源获取和运营资源获取具有正影响,知识资源与新企业绩效显著正相关,知识资源获取对运营资源获取具有正影响.研究结论还表明运营资源对新企业绩效无显著影响,但知识资源可以加强两者之间关系,说明新企业只有具备很强的资源管理能力才能将运营资源转化为企业绩效.     

面向价值网络的企业协同竞争博弈模型研究

运用演化博弈理论的方法,分析价值网络模式下企业的协同竞争机制,构建企业主体间协同竞争的演化博弈模型,指出价值网络模式下企业协同竞争行为的博弈过程及特点,揭示出系统的初始状态、发展阶段及利益分配机制对演化博弈过程的影响机理。