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.     

Combining Linear and Non-Linear Objectives in Spanning Tree Problems

A classical approach to multicriteria problems asks for the optimization of a suitable linear combination of the objectives. In this work we address such problems when one of the objectives is the linear function, the other is a non-linear one and we seek for a spanning tree of a given graph which optimizes the combination of the two functions. We consider both maximization and minimization problems and present the complexity status of 56 such problems, giving, whenever possible, polynomial solution algorithms.     

基于非参数估计框架的期望效用最大化最优投资组合

本文基于期望效用最大化和非参数估计框架研究了最优投资组合选择问题。和以往大多文献假定资产收益率服从某些特定分布不同资产收益率的分布类型无需作任何假设。首先在一般效用函数下,利用组合收益率密度函数的非参数核估计给出了期望效用的基本非参数估计公式,并建立了期望效用最大化投资组合选择问题的基本框架。然后,在投资者具有幂效用函数的假定下,给出了期望效用具体的非参数计算公式,并给出了求解最大期望效用的数值算法。最后,利用中国证券交易所11支股票日收益率的真实数据给出了一个数值算例。本文提出的非参数估计框架具有一般性,还可以进一步用来研究各种现实条件下（如各种现实不等式约束和具有交易成本）的投资组合管理问题。     

期望未来损失约束下的最优投资问题

在标准的Black-Scholes 型金融市场下,建立了期望未来损失( expected future loss;EFL)约束下基于终端财富效用最大化的投资组合选择模型.运用鞅和优化方法,得到了一般效用投资者在投资计划期内任意时刻的最优财富和最优投资组合选择策略.在对数效用函数下,得到了投资者在投资计划期内任意时刻的最优财富和最优投资组合选择策略的显式表达式.     

PORTFOLIOS OF RISKY PROJECTS

The problem of selecting a portfolio from a set of independent risky business ventures is formulated in terms of maximization of the risk-adjusted (certainty-equivalent) profit of the portfolio, based upon the exponential utility function. Objects of investment include fractional participation (risk sharing) in projects with other firms, where costs and returns are shared in the same proportion. The method assumes that project costs are certain. Project revenues are uncertain, and any probability function for revenue can be used.     

考虑交易成本的投资组合效率估计方法

投资组合绩效评价是学术界研究的热点问题。本文在经典的经济学框架下,基于真实前沿面,给出了投资组合效率的明确定义。由于实际投资环境的影响,投资组合优化模型非常复杂,难以获得真实前沿面的解析解,这给投资组合效率的应用带来了很大的困难。本文基于投资组合理论,在投资组合模型所对应的前沿面为凹函数的情况下,采用基于数据的投资组合DEA评价模型构造前沿面来逼近真实的前沿面,从而估计一般情形下投资组合的效率。在此基础上研究了考虑交易成本的投资组合效率评价问题,并用实例说明了本文方法的合理性与可行性。     

基于差异系数σ/μ的最优投资组合方法

本文以Markowitz均值-方差模型为基础,提出了差异系数σ/μ极小化以及在此条件下的组合收益率极大化的均衡理论,利用Lagrange参数法,得到了一种使单位收益风险最小的投资组合决策方法,并给出了实例分析。     

基于投资者情绪的投资组合模型研究

本文在假设投资者风险厌恶、且其风险厌恶程度受其情绪影响的条件下,以投资者效用最大化为决策目标,建立基于投资者情绪的投资组合模型从理论上研究投资者情绪对投资组合结构及其收益-风险关系的影响。研究结果表明,当投资者过度乐观时,其将通过银行借贷融资等方式购买超额风险资产;当投资者情绪处于相对理性状态时,其将合理分配无风险资产和风险资产的投资比例;当投资者情绪处于悲观状态时,其将卖空风险资产。当投资者情绪处于过度乐观和相对理性状态时,投资组合预期超额收益与风险正相关;当投资者情绪处于悲观状态时,投资组合预期超额收益与风险负相关。论文研究结果修正了前人的相关研究结论,是对传统投资组合理论的深化和发展。     

基于投资组合和现金流的风险投资退出决策研究

本文借鉴投资组合理论,结合项目组合现金流的特点,构建了风险投资项目组合的决策模型,并设计了模型的动态规划求解方法。该模型在保证现金资源合理配置的前提下,考虑了风险投资组合退出的时机与方式,实现了全局收益的最大化。     

A PENSION DECISION MODEL FOR THE EMPLOYER*

Recently, the Financial Accounting Standards Board (FASB) reevaluated accounting for pension plans. The issue is emotional and highly political in nature. The FASB attempted to justify its approach on the basis of measuring economic activity, but it failed to provide much in the way of analytical support. This paper provides a managerial decision model and an economic basis for the existence of pension plans. A pension plan is described as a cost-saving, risk-sharing, incentive contract. The analysis is developed using agency theory. The model presented here meets three suggested objectives of an employer: 1. Maximization of utility through the maximization of profit 2. Ability to conform the risk characteristics of an employment contract to the risk characteristics of the employer 3. Diversification of the risk inherent in the employment contract Profit is maximized by producing cost savings associated with employee tenure and loyalty. Sharing cost savings with employees (i.e., offering a pension plan) meets the above objectives. The employer determines the optimal sharing rate for the expected cost savings. An examination of the employer's underlying decision process reveals implications for pension plan accounting which generally are consistent with and support the FASB's Statement of Financial Accounting Standards No. 87 [5].     

生产性财政支出、经济增长与社会福利最大化

从理论与实证两个方面研究生产性财政支出对经济增长与社会福利的促进作用这一财政领域十分关注的问题.理论研究中,通过构建包含政府财政消费性支出和生产性支出的内生增长模型,推导了经济增长和社会福利最大化目标下各自最优的生产性财政支出结构,并分析了政府生产性财政支出在两目标下最优支出结构的差异及原因.实证研究发现,2004年～2012年间,中国的东、中、西三大经济带政府生产性支出在社会福利目标下的最优占比普遍低于经济增长目标;而在2004年～2008年间,政府实际的生产性财政支出占比还未达到两目标下的最优占比值,政府的生产性财政支出还有进一步提升的空间;但在2009年～2012年间,政府实际的生产性财政支出占比已接近甚至超过了两目标下的最优占比值,继续增加生产性财政支出将对经济增长与社会福利的提升都产生抑制作用,尤其在东部地区、中部地区更为明显.因此,在中国经济发展进入"新常态"时期,政府更需审时度势、通过适时优化财政支出以促进经济增长与社会福利的最大化.     

A practical LP model for equity portfolios

A linear programming portfolio selection model is formulated, taking into consideration the objectives and constraints which are imposed on portfolio managers. The composition of portfolios determined by the use of the model are compared to actual portfolios determined by portfolio managers without the use of any quantitative model. The practical use of the model is evaluated and conclusions are reported.     

金融网络风险下多因子矩阵回归的资产组合与定价

本文从企业的股权、债权关系出发,基于违约距离构建无向图网络,分析了不确定性风险以网络形式进行传染、溢出和蔓延等现象,通过最小生成树的稀疏网络优化方法最大限度降低资产组合的非线性风险影响。站在资源配置的角度,利用稀疏聚类算法深入挖掘资产特征和捕捉其间的相依关系,采用多目标、多指数的稳健矩阵回归策略动态跟踪市场趋势,并通过自适应权重学习策略对网络风险叠加影响下的资产组合进行选择和配置,最终获得最小生成树风险下投资组合的稀疏聚类优化策略,进一步扩充了资产定价多因子模型。研究发现多目标矩阵回归的稀疏聚类投资组合,不仅对组合内投资标的进行了选择性舍弃,使资金能够集中配置于优质资产,更有助于通过最小生成树减缓甚至切断风险在网络中的传播,有效降低了资产之间风险的传染性。基于金融网络的风险分析方法不仅有效地刻画了风险以网络方式互相传染、互相影响、互相强化的非线性叠加效应,而且通过资产之间配置系数的压缩变换和最小生成树的优化方式,最小化最坏情形下风险传染的影响,对复杂网络环境下的资产配置和全面风险管理进行了有益补充,为长期投资基金获得风险和收益更为均衡的资产配置,提供了合意的投资策略和决策依据。     

Selection of supply portfolio under disruption risks

This paper deals with the optimal selection of supply portfolio in a make-to-order environment in the presence of supply chain disruption risks. Given a set of customer orders for products, the decision maker needs to decide from which supplier to purchase custom parts required for each customer order to minimize total cost and mitigate the impact of disruption risks. The selection of suppliers and allocation of orders is based on price and quality of purchased parts and reliability of delivery. The two types of disruption scenarios are considered: scenarios with independent local disruptions of each supplier and scenarios with local and global disruptions that may result in all suppliers disruption simultaneously. The problem is formulated as a single- or bi-objective mixed integer program and a value-at-risk and conditional value-at-risk approach is applied to control the risk of supply disruptions. The proposed portfolio approach is capable of optimizing the supply portfolio by calculating value-at-risk of cost per part and minimizing expected worst-case cost per part simultaneously. Numerical examples are presented and some computational results are reported.     

基于股价预测的泛证券投资组合策略

本文基于期望效用最大化和L₁-中位数估计研究了在线投资组合选择问题。与EG（Exponential Gradient）策略仅利用单期价格信息估计价格趋势不同,本文将利用多期价格信息估计价格趋势,以提高在线策略的性能。首先,基于多期价格数据,利用L₁-中位数估计得到预期价格趋势。然后,通过期望效用最大化,提出一个新的具有线型时间复杂度的在线策略,EGLM（Exponential Gradient via L₁-Median）。并通过相对熵函数定义资产权重向量的距离,进而证明了EGLM策略具有泛证券投资组合性质。最后,利用国内外6个证券市场的历史数据进行实证分析,结果表明相较于UP（Universal Portfolio）策略和EG策略,EGLM策略有更好的竞争性能。     

基于企业转型目标的产品组合策略选择模型

在产业升级的背景下，企业面临转型的机遇和任务。当前企业转型的经济转化能力较弱，其主要原因是企业忽略了转型目标与产品组合策略相匹配的重要作用。本文提出转型目标一致性的概念来衡量产品组合策略与转型目标的匹配程度，基于模糊DEA方法构建了基于转型目标一致的产品组合策略选择模型。以产业相关转型的企业为对象进行实例分析，验证了模型的可操作性。具有转型目标一致性的产品组合策略更能满足企业转型发展的需要，创造更好的经济和社会效益。模型为企业成功转型和制定相应的产品组合策略提供了指导意见。     

Application of the Fuzzy Weighted Average in Strategic Portfolio Management*

We propose a systematic approach that incorporates fuzzy set theory in conjunction with portfolio matrices to assist managers in reaching a better understanding of the overall competitiveness of their business portfolios. Integer linear programming is also accommodated in the proposed integrated approach to help select strategic plans by using the results derived from the previous portfolio analysis and other financial data. The proposed integrated approach is designed from a strategy‐oriented perspective for portfolio management at the corporate level. It has the advantage of dealing with the uncertainty problem of decision makers in doing evaluation, providing a technique that presents the diversity of confidence and optimism levels of decision makers. Furthermore, integer linear programming is used because it offers an effective quantitative method for managers to allocate constrained resources optimally among proposed strategies. An illustration from a real‐world situation demonstrates the integrated approach. Although a particular portfolio matrix model has been adopted in our research, the procedure proposed here can be modified to incorporate other portfolio matrices.     

Strategy and the “business portfolio”

In this article the author goes on to develop the conclusion reached in his previous article which appeared in the December edition of Long Range Planning. These conclusions concerned the requirements for strategic success for an individual business, here they are developed into their implications for strategy development in the typical multibusiness company.It is argued that relative competitive position and growth are the two fundamental parameters which must be considered in determining the strategy that an individual business should follow when viewed within the context of the company's overall ‘business portfolio’. The likely patterns of business strategy which will lead to overall corporate success are discussed and contrasted with those which can lead to disaster.The key is that strategies should be made to differ widely from business to business, as a function of the growth and relative competitive position of each business and the company's overall resource position particularly with respect to cash. The ‘across the board’ defensive measures which many companies have adopted in recent years as their response to the pressures of inflation and recession are therefore argued to be singularly inappropriate for the long term. The ‘business portfolio’ concept provides a superior approach for developing the differentiated strategic business objectives which are necessary for any company to make the most of its opportunities.     

OPTIMIZING AND SATISFICING IN STOCHASTIC COST-VOLUME-PROFIT ANALYSIS

This paper examines some of the implications of introducing penalties for output not equalling demand by employing a general stochastic model for a firm facing an uncertain demand with a known probability density function. Several alternative objectives of the firm are considered: (1) maximization of expected profits; (2) maximization of the probability of achieving a particular target level of profits; and (3) maximization of target profits, given a target level of the probability of their being achieved. It is shown that the resulting probability density function of profits is not well defined. The shape and location of the function depend on the relative magnitudes of the model parameters and the output decision. Several important implications of this result for cost-volume-profit analysis are discussed.     

非完全市场条件下的0-水平资产定价法研究

资产的0-水平定价法是指投资者在特定的效用函数和财富水平状况下已取得的最优投资组合,不会因新的资产出现及其相应的定价而调整,即对新资产的定价使追求效用最大化的投资者对新资产的最佳持有量为零。因此对新资产采用0-水平定价不会使市场产生套利机会。本文主要介绍Lenberger等人提出的0-水平定价的概念、方法及性质,并且将这种定价方法与e-套利定价方法进行比较,然后证明了在局部完全市场里,0-水平定价与e-套利定价的一致性。