我国生鲜蔬菜供应链问题及优化研究

近年来,随着农业产业结构的调整和农业技术的进步,我国生鲜蔬菜供给量稳步增长,产品结构不断优化,基本能够满足社会需求。但是由于生鲜蔬菜具有较强季节性、地域性和易腐性,这对生鲜蔬菜的储运、加工、运输、销售等物流环节提出了特殊的要求。生鲜蔬菜的这种特性决定了其在供应链管理活动中具有自身的独特性,这就需要我们综合的考虑生鲜蔬菜从农户到餐桌等各个环节,运用现代供应链理念和技术,构建反应灵敏、反馈及时、质量安全、符合市场需求的生鲜蔬菜供应链模式。文中从分析生鲜蔬菜供应链的特性入手,分析了我国生鲜蔬菜供应链存在的问题,并提出了有效的整合生产组织成员、全程冷藏运输、构建生鲜蔬菜物流信息平台、建立健全蔬菜质量监督管理系统等优化生鲜蔬菜供应链的措施。     

协同机制下供应链剩余利润合理分配的影响因素研究

首先论述了供应链剩余利润以及该利润分配在协同供应链系统中的重要作用,分析了影响利润分配的系统外部和内部的各种因素,并利用层次分析法确定了供应链成员协作满意度和所担风险两个关键因素,指出了在有限条件下协同供应链剩余利润分配研究的重点。     

中国省际劳均收入的收敛研究——基于核密度函数和Markov随机过程理论的分析

采用核密度函数和Markov随机过程理论研究了我国省区劳均收入分布的动态演变和发展趋势。研究发现,改革前我国省区劳均收入为多峰分布,其遍历分布为偏向低收入的双峰分布;改革后,劳均收入分布经历了从多峰到单峰再到双峰的演变过程,其遍历分布为偏向高收入的双峰分布。从长期发展趋势看,改革后我国多数地区将会收敛于高收入区间。     

EXPLICIT SOLUTIONS OF CONSUMPTION-INVESTMENT PROBLEMS IN FINANCIAL MARKETS WITH REGIME SWITCHING

We consider a consumption and investment problem where the market presents different regimes. An investor taking decisions continuously in time selects a consumption–investment policy to maximize his expected total discounted utility of consumption. The market coefficients and the investor's utility of consumption are dependent on the regime of the financial market, which is modeled by an observable finite-state continuous-time Markov chain. We obtain explicit optimal consumption and investment policies for specific HARA utility functions. We show that the optimal policy depends on the regime. We also make an economic analysis of the solutions, and show that for every investor the optimal proportion to allocate in the risky asset is greater in a "bull market" than in a "bear market." This behavior is not affected by the investor's risk preferences. On the other hand, the optimal consumption to wealth ratio depends not only on the regime, but also on the investor's risk tolerance: high risk-averse investors will consume relatively more in a "bull market" than in a "bear market," and the opposite is true for low risk-averse investors.     

Median‐voter Equilibria in the Neoclassical Growth Model under Aggregation*

We study a dynamic version of Meltzer and Richard's median‐voter model where agents differ in wealth. Taxes are proportional to income and are redistributed as equal lump‐sum transfers. Voting occurs every period and each consumer votes for the tax that maximizes his welfare. We characterize time‐consistent Markov‐perfect equilibria twofold. First, restricting utility classes, we show that the economy's aggregate state is mean and median wealth. Second, we derive the median‐voter's first‐order condition interpreting it as a tradeoff between distortions and net wealth transfers. Our method for solving the steady state relies on a polynomial expansion around the steady state.     

MC's for MCMC'ists

We develop a minimum amount of theory of Markov chains at as low a level of abstraction as possible in order to prove two fundamental probability laws for standard Markov chain Monte Carlo algorithms:
1. The law of large numbers explains why the algorithm works: it states that the empirical means calculated from the samples converge towards their "true" expected values, viz. expectations with respect to the invariant distribution of the associated Markov chain (=the target distribution of the simulation).
2. The central limit theorem expresses the deviations of the empirical means from their expected values in terms of asymptotically normally distributed random variables. We also present a formula and an estimator for the associated variance.     

A useful tool for forecasting the Euro-area business cycle phases

Based on a novel extension of existing multivariate Markov-switching models, we provide the reader with a useful tool for analyzing current business conditions and making predictions about the future state of the Euro-area economy in real time. Apart from the Industrial Production Index, we find that the European Commission Industrial Confidence Indicator, which is issued with no delay, is very useful for constructing the real-time predictions.     

Stationary measures for some Markov chain models in ecology and economics

Summary. Let continuous, exists in for x in . Let be an i.i.d. sequence from F and X₀ be a nonnegative random variable independent of . Let be the Markov chain generated by the iteration of random maps by . Such Markov chains arise in population ecology and growth models in economics. This paper studies the existence of nondegenerate stationary measures for {X_n}. A set of necessary conditions and two sets of sufficient conditions are provided. There are some convergence results also. The present paper is a generalization of the work on random logistics maps by Athreya and Dai (2000).Received: 20 March 2002, Revised: 4 December 2002, JEL Classification Numbers: C22, D9.The author wishes to thank Professor Mukul Majumdar and the referees for several useful suggestions.     

企业供应链成本管理方法与关键环节

市场竞争已成为供应链与供应链之间的角逐,如何加强企业供应链成本的控制和管理,是现代企业不得不面对的重要问题。本文选取了两种较新的成本管理方法——供应链平衡计分法和作业成本法加以分析,并对实施过程中应注意的关键问题进行了探讨。