基于六西格玛流程改进的库存管理优化

库存管理是企业用来控制实际库存问题的方法，主要帮助企业经营者确定何时补充订货、补充订货多少以及安全库存等问题。现有的库存控制研究往往只关注数学建模阶段的精确性，而对库存波动根源认识不足，导致数学模型越来越复杂、完善，但库存仍然居高不下、难以控制。本文针对该问题，提出了在库存管理中糅合六西格玛管理理念的思想，通过六西格玛方法揭示库存积压的根源，从源头着手，进行流程改进，从而达到库存优化、提高客户满意度的目的。文章通过实际案例证实了基于六西格玛理念的库存优化管理的有效性。     

On estimating the mean of the selected normal population under the LINEX loss function

Following Parsian and Farsipour (1999), we consider the problem of estimating the mean of the selected normal population, from two normal populations with unknown means and common known variance, under the LINEX loss function. Some admissibility results for a subclass of equivariant estimators are derived and a sufficient condition for the inadmissibility of an arbitrary equivariant estimator is provided. As a consequence, several of the estimators proposed by Parsian and Farsipour (1999) are shown to be inadmissible and better estimators are obtained. Received January 2001/Revised May 2002     

基于模糊熵和多目标规划的公路货运交通枢纽布局模型

针对货运交通枢纽布局问题,首先利用模糊熵获得指标的权重,集结指标值后得到备选交通枢纽的综合评价值,建立一个多目标规划模型来最小化交通成本,最大化建设枢纽的综合评价值,求解后确定货运枢纽的位置、数量、容量等级。     

三层次供应链中最优库存决策

本文研究由多供应商、多制造商和多零售商构成的三层次供应链最优库存模型,在供应链中引入协调机制使整个供应链库存总费用最小.     

供应链在逆向物流下的最优库存比较研究

供应链中的库存协调是供应链管理的一项重要工作。文中分析研究了由一个供应商和一个生产商组成的供应链在集成条件下和分散条件下的最优库存,并求解在一种逆向物流情况下,能有效提高供应链整体效率的库存。     

Selecting Sites for New Facilities Using Data Envelopment Analysis

This paper develops a mathematical programming model for obtaining a best set of sites for planned facilities. The model is concerned with those situations where resource constraints are present. The specific setting for the paper involves the selection of sites for a set of retail outlets, wherein the ratio of aggregate outputs to inputs for the selected set is maximal among all possible sets that could be chosen. At the same time, the model guarantees that the only sets of stores allowable are those for which the available resources are used to the maximum extent possible.     

三阶随机占优准则在证券选择中的应用

通常可以用分布函数和分住数函数描述随机占优准则,Man-Chung Ng列举的两个例子说明在三阶随机占优条件下用两种方法得到的结论是不一致的,这与Levy的观点相反。该文分别将这两种方法描述的三阶随机占优准则用于上海证券市场的基金选择,发现用两种方法在应用中得到的结论并不总是一致的。由此验证用Levy提出的分位数方法描述的随机占优准则进行实证研究是不正确的,一阶和二阶条件除外。     

我国水上石油物流系统优化问题探讨

随着我国石油需求量及进出口量的不断增长,研究我国水上石油物流系统的优化问题日益重要,本文首先分析了水上石油物流系统研究的必要性,对国内外关于石油物流系统研究现状进行了评述,提出了我国水上石油物流系统优化问题的研究思路和方法.     

Forecasting economic time series using flexible versus fixed specification and linear versus nonlinear econometric models

Nine macroeconomic variables are forecast in a real-time scenario using a variety of flexible specification, fixed specification, linear, and nonlinear econometric models. All models are allowed to evolve through time, and our analysis focuses on model selection and performance. In the context of real-time forecasts, flexible specification models (including linear autoregressive models with exogenous variables and nonlinear artificial neural networks) appear to offer a useful and viable alternative to less flexible fixed specification linear models for a subset of the economic variables which we examine, particularly at forecast horizons greater than 1-step ahead. We speculate that one reason for this result is that the economy is evolving (rather slowly) over time. This feature cannot easily be captured by fixed specification linear models, however, and manifests itself in the form of evolving coefficient estimates. We also provide additional evidence supporting the claim that models which ‘win’ based on one model selection criterion (say a squared error measure) do not necessarily win when an alternative selection criterion is used (say a confusion rate measure), thus highlighting the importance of the particular cost function which is used by forecasters and ‘end-users’ to evaluate their models. A wide variety of different model selection criteria and statistical tests are used to illustrate our findings.     

Risky allocations from a risk-neutral informed principal

We study a model of informed principal with private values where the principal is risk neutral and the agent is risk averse. We show that the principal, regardless of her type, gains by not revealing her type to the agent through the contract offer. The equilibrium allocation transfers some ex-ante risk from one type of agent to the other. Despite the increase in the principal's surplus, allocative efficiency does not necessarily improve. Received: 26 January 2004, Accepted: 5 May 2005 JEL Classification: C72, D23, D82 I would like to thank my supervisor Leonardo Felli for suggestions and Leo Ferraris for helpful discussions. All remainig errors are my own.