天然林保护工程的成效及对策探析

我国的天然林保护工程从1998年开始试点,2000年10月经国务院正式批准实施。该工程是我国针对生态环境不断恶化的趋势实施的六大林业重点工程之一。自工程实施十年以来,取得了显著的成效,但同时也暴露出一系列的问题。     

延迟支付下短生命周期产品批发价契约研究

在需求随机且允许延迟支付的情况下,如果零售商的销售款不足以清偿应支付给制造商的货款,制造商将承担一定的回款风险。对此,以报童模型为基础,针对短生命周期产品建立了延迟支付下的批发价契约模型。分析表明,如果需求分布是IGFR,那么对于一定的批发价,零售商有确定的最优订货批量。制造商的预期利润是批发价的递增函数。制造商根据零售商至少应获得的预期利润来确定批发价。当满足一定条件时供应链能够实现协调,但这是一种系统利润分配缺乏柔性的协调。     

参与式方法在退耕还林工程中的应用分析

参与式方法是参与式发展的重要概念和基本方法。参与式方法在退耕还林过程中的应用体现了农民的主体地位,维护了农民的权益,改善了干群关系,提高了政策执行效果。随着退耕还林工程的延续和生态文明的推进,参与式方法的应用将会越来越广。但是受各种因素的制约,目前参与式方法在退耕还林过程中应用得还不够普遍。     

航班延误的界定及民事责任分析

航班延误是困扰民航运输领域的长久难题。《华沙公约》及中国《民用航空法》都未给出＂航班延误＂的明确定义。从是否超出正常的离站时间和是否在合理期间内到达目的地两方面判断,航班延误是指承运人未按约定时间将旅客送抵最终目的地,若在无约定的情况下,应以完成运输所需的合理时间来判断是否构成延误。依据＂合理性＂标准来划分航班延误,合理延误的承运人虽对延误不承担损害赔偿责任,但对未履行法定附随义务仍承担责任;不合理延误的承运人除承担＂可预见性＂的旅客损失以外,还要独立承担违约金责任。     

Bargaining with Interdependent Values

A seller and a buyer bargain over the terms of trade for an object. The seller receives a perfect signal that determines the value of the object to both players, whereas the buyer remains uninformed. We analyze the infinite‐horizon bargaining game in which the buyer makes all the offers. When the static incentive constraints permit first‐best efficiency, then under some regularity conditions the outcome of the sequential bargaining game becomes arbitrarily efficient as bargaining frictions vanish. When the static incentive constraints preclude first‐best efficiency, the limiting bargaining outcome is not second‐best efficient and may even perform worse than the outcome from the one‐period bargaining game. With frequent buyer offers, the outcome is then characterized by recurring bursts of high probability of agreement, followed by long periods of delay in which the probability of agreement is negligible.     

三峡地区的扶贫与环境保护

贫困与环境之间存在着循环关系,三峡工程的兴建给三峡地区的扶贫与环境保护增添了新的变数,要使三峡地区从贫困与环境恶化的怪圈走向扶贫与环境保护的良性互动,必须采取扶贫与环境保护相结合的对策。     

Eyes on the Block: Measuring Urban Physical Disorder Through In-Person Observation

In this paper, we present results from measuring physical disorder in Los Angeles neighborhoods. Disorder measures came from structured observations conducted by trained field interviewers. We examine inter-rater reliability of disorder measures in depth. We assess the effects of observation conditions on the reliability of reporting. Finally, we examine the relationships between disorder, other indicators of neighborhood status, and selected individual outcomes.Our results indicate that there is considerable variation in the level of agreement among independent observations across items, although overall agreement is moderate to high. Durable indicators of disorder provide the most reliable measures of neighborhood conditions. Circumstances of observation have statistically significant effects on the observers’ perceived level of disorder. Physical disorder is significantly related to other indicators of neighborhood status, and to children’s reading and behavior development.This result suggests a need for further research into the effects of neighborhood disorder on children.     

基于SVM的建设项目风险识别方法研究

支持向量机(SVM)是在统计学习理论的基础上发展起来的一种新的机器学习方法。它基于结构风险最小化原则,能有效地解决过学习问题,具有良好的推广性和分类精确性。在项目风险管理中,风险识别是很重要的一个步骤,如果风险不能被识别,那么我们就不能对风险进行转移、控制或管理。针对该问题,本文提出了一种新的风险识别方法-支持向量机,利用该方法对项目风险识别进行了研究,并取得了很好的识别效果。     

多主体参与项目治理:行政干预还是市场调节?——以农业标准化示范项目为例

多主体参与项目治理是项目制在实践过程中表现出的一种普遍治理形态和经验模式,是长期以来"有为政府"干预和"有效市场"调节共同作用的一个结果。回顾历史,我国农业标准化示范项目经历了从政府单一主体管理到向以农业企业为代表的多主体共治的转变,这一转变对项目参与主体地位、资金配置、协商机制产生了重要影响。推动这一结构转变的因素主要包括两方面:一是制度和市场条件逐渐成熟,即"政府适时适当的宏观调控"和"逐步完善的市场机制";二是政府与农业新型经营主体的需求日渐凸显,即"政府的有为需要市场力量"与"市场主体发挥了有效作用"。     

Global stability of stochastic systems with Poisson distributed random time-delay

This paper gives global stability criteria for a controlled stochastic system with randomly distributed time-delay. The delay function is governed by a homogeneous Poisson process and is independent of the stochastic perturbation on the system. A delay-dependent gain controller is constructed and used to develop a stabilization criterion for the system. Based on the Lyapunov-Krasovskii functional method and stochastic analysis theory, notions of stochastic stability are examined in terms of linear matrix inequality and global stability criteria derived.