粮食最优储备规模研究进展及启示

粮食高库存威胁粮食市场稳定和国家粮食安全,优化粮食储备规模是当前粮食政策调整的关键。如何确定粮食最优储备规模？国内外学者对此展开了大量研究。国外研究从历史经验法起步,进一步提出能够反映储备多目标特征的目标规划法,以及能够根据市场情况调整最优储备规模的动态规划法,极大推动了粮食最优储备规模相关研究。中国学者普遍采用差额补偿法估算粮食最优储备规模,从单边补偿、双边调节和需求补偿三个角度丰富了差额补偿法。但总的来看,国内研究方法相对固化,对粮食储备及整个市场的刻画比较粗略,难以满足当前粮食市场发展和政策调整的需要。在当前中国粮食政策调整的紧要关头,有必要借鉴国外研究经验、基于中国现实情况,拓展和深化国内粮食最优储备规模研究。     

节能减排政府补贴的最优边界问题研究

补贴是我国政府在节能减排领域常见的政策手段之一.本文借助信号博弈理论探究了政府与企业在节能减排补贴申请与发放过程中双方策略的选择与依存性变化,据此及节能减排效果影响因素,建立了动态方程.首先根据不同策略下各方得益情况确定在市场完全成功情况下,分析了实现均衡状态的充分条件;然后借助随机微分方程理论,以分离均衡状态作为初始状态,探究该状态得以保持稳定并延续所需满足的约束条件,依据所构建理论模型分析了补贴额、违规成本、积极性挫伤损失实现分离均衡的最优边界,并运用Matlab软件做数值模拟以验证模型的有效性,为改善减排效果提供理论上的借鉴与指导.     

浅谈休闲农业

在人类社会的发展中 ,资源的稀缺性要求我们人类对资源要进行优化配置 ,并能充分发挥其效用 ,使资源能够永续利用 ,持续发展。可持续发展是一种多要素的、全方位的、综合的发展 ,有经济因素 ,也有非经济因素。而资源 ,如土地、水、矿产等 ,它是生产的原料来源和布局场所 ,是不可再生资源 ,这些自然资源不仅具有使用价值 ,而且在其利用和开发的过程中 ,呈现出越来越明显的有限性或稀缺性。自然资源的永续利用是可持续发展的物质基础和基本条件。针对农业的多功能特点 ,运用帕累托最优准则 ,在高潜力和低潜力地区实施休闲农业 ,使农业和乡村可持续发展     

Two applications of a theorem of Dvoretsky, Wald, and Wolfovitz to cake division

In this note, we show that a partition of a cake is Pareto optimal if and only if it maximizes some convex combination of the measures used by those who receive the resulting pieces of cake. Also, given any sequence of positive real numbers that sum to one (which may be thought of as representing the players' relative entitlements), we show that there exists a partition in which each player receives either more than, less than, or exactly his or her entitlement (according to his or her measure), in any desired combination, provided that the measures are not all equal.     

Expert rule versus majority rule under partial information

We study the uncertain dichotomous choice model. Under some assumptions on the distribution of expertise of the various panel members, the probability of the expert rule to be the optimal one is compared to that of the majority rule to be optimal. It turns out that for the former probability exceeds the latter by far, especially as the panel size becomes large.     

A new financial risk ratio

Randomness in financial markets has been recognized for over a century: Bachelier (1900), Cowles (1932), Kendall (1953), and Samuelson (1959). Risk thus enters into efficient portfolio design: Fisher (1906), Williams (1936), Working (1948), Markowitz (1952). Reward versus risk decisions then depend upon utility to the investor: Bernoulli (1738), Kelly (1956), Sharpe (1964), and Modigliani (1997). Returns of a portfolio adjusted to risk are measured by a number of ratios: Treynor, Sharpe, Sortino, M2, among others. I will propose a refinement of such ratios. This possibility was mentioned in my recent book: Antieigenvalue analysis, World-Scientific (2011). The result is a new set of growth-to-return risk-based financial ratios of ratios.     

Optimal PPS Sampling with Vanishing Auxiliary Variables – with Applications in Microscopy

Recently, non‐uniform sampling has been suggested in microscopy to increase efficiency. More precisely, proportional to size (PPS) sampling has been introduced, where the probability of sampling a unit in the population is proportional to the value of an auxiliary variable. In the microscopy application, the sampling units are fields of view, and the auxiliary variables are easily observed approximations to the variables of interest. Unfortunately, often some auxiliary variables vanish, that is, are zero‐valued. Consequently, part of the population is inaccessible in PPS sampling. We propose a modification of the design based on a stratification idea, for which an optimal solution can be found, using a model‐assisted approach. The new optimal design also applies to the case where ‘vanish’ refers to missing auxiliary variables and has independent interest in sampling theory. We verify robustness of the new approach by numerical results, and we use real data to illustrate the applicability.     

Optimal Coordination in Distributed Software Development

The construction of a software system requires not only individual coding effort from team members to realize the various functionalities, but also adequate team coordination to integrate the developed code into a consistent, efficient, and bug‐free system. On the one hand, continuous coding without adequate coordination can cause serious system inconsistencies and faults that may subsequently require significant corrective effort. On the other hand, frequent integrations can be disruptive to the team and delay development progress. This tradeoff motivates the need for a good coordination policy. Both the complexity and the importance of coordination is accentuated in distributed software development (DSD), where a software project is developed by multiple, geographically‐distributed sub‐teams. The need for coordination in DSD exists both within one sub‐team and across different sub‐teams. The latter type of coordination involves communication across spatial boundaries (different locations) and possibly temporal boundaries (different time zones), and is a major challenge that DSD faces. In this study, we model both inter‐ and intra‐sub‐team coordination in DSD based on the characteristics of the systems being developed by the sub‐teams, the deadline for completion, and the nature of division adopted by the sub‐teams with respect to development and integration activities. Our analysis of optimal coordination policies in DSD shows that integration activities by one sub‐team not only benefit that sub‐team (as is the case in co‐located development) but can also help the other sub‐teams by providing greater visibility, thereby resulting in a higher integration frequency relative to co‐located development. Analytical results are presented to demonstrate how the characteristics of the projects and the sub‐teams, and the efficiency of communication across the sub‐teams, affect coordination and productivity. We also investigate the pros and cons of using specialized integration sub‐teams and find that their advantage decreases as the project schedule becomes tighter. Decentralized decisions and asymmetric subsystems are also discussed.     

基于顾客学习行为的供应链契约协调研究

由于策略型顾客的存在,顾客社会学习行为对产品的动态价格、最优库存以及供应链的协调契约均具有重要影响。在集中供应链环境下探讨基于顾客学习行为的最优运营决策,研究二级分散供应链中顾客学习行为对收益分享契约、回购契约和销售折扣契约的影响。指出传统的收益分享契约和销售折扣契约虽能协调供应链,但前者必须满足顾客学习能力达到某固定值的条件,后者则不能以任意比例分割供应链利润,基于此提出基于销售期的差别回购契约,即无论顾客学习能力为何值其均能协调供应链,并且能以任意比例分割供应链利润,以期为顾客学习行为理论夯实基础。     

人口统计特征对酒店员工内在动机的影响 ——基于长沙市高星级酒店调查数据分析

通过对长沙市部分高星级酒店实施问卷调查获得的366份调查表,进行内在动机量表的信度与效度以及内在动机的最优尺度回归分析,得知人口统计特征变量对内在动机影响的相对重要性,在人口统计特征中,工龄对内在动机的影响最大,其次是年龄和受教育程度,性别对内在动机并无显著影响。