DERIVATION OF THE GAMMA DISTRIBUTION BY USING THE PRINCIPLE OF MAXIMUM ENTROPY (POME)1

The principle of maximum entropy (POME) was used to derive the two-parameter gamma distribution used frequently in synthesis of instantaneous or finite-period unit hydrographs. The POME yielded the minimally prejudiced gamma distribution by maximizing the entropy subject to two appropriate constraints which were the mean of real values and the mean of the logarithms of real values of the variable. It provided a unique method for parameter estimation. Experimental data were used to compare this method with the methods of moments, cumulants, maximum likelihood estimation, and least squares.     

Viability analysis of management frameworks for fisheries

The pressure on marine renewable resources has rapidly increased over past decades. The resulting scarcity has led to a variety of different control and surveillance instruments. Often they have not improved the current situation, mainly due to institutional failure and intrinsic uncertainties about the state of stocks. This contribution presents an assessment of different management schemes with respect to predefined constraints by utilizing viability theory. Our analysis is based on a bio-economic model which is examined as a dynamic control system in continuous time. Feasible development paths are discussed in detail. It is shown that participatory management may lead to serious problems if a purely resource-based management strategy is employed. The analysis suggests that a less risky management strategy can be implemented if limited data are available.     

Relaxation algorithms to find Nash equilibria with economic applications

Recent theoretical studies have shown that a relaxation algorithm can be used to find noncooperative equilibria of synchronous infinite games with nonlinear payoff functions and coupled constraints. In this study, we introduce an improvement to the algorithm, such as the steepest-descent step-size control, for which the convergence of the algorithm is proved. The algorithm is then tested on several economic applications. In particular, a River Basin Pollution problem is considered where coupled environmental constraints are crucial for the relevant model definition. Numerical runs demonstrate fast convergence of the algorithm for a wide range of parameters. This revised version was published online in July 2006 with corrections to the Cover Date.     

Time stress,predation risk and diurnal–nocturnal foraging trade-offs in larval prey

Insect larvae increase in size with several orders of magnitude throughout development making them more conspicuous to visually hunting predators. This change in predation pressure is likely to impose selection on larval anti-predator behaviour and since the risk of detection is likely to decrease in darkness, the night may offer safer foraging opportunities to large individuals. However, forsaking day foraging reduces development rate and could be extra costly if prey are subjected to seasonal time stress. Here we test if size-dependent risk and time constraints on feeding affect the foraging–predation risk trade-off expressed by the use of the diurnal–nocturnal period. We exposed larvae of one seasonal and one non-seasonal butterfly to different levels of seasonal time stress and time for diurnal–nocturnal feeding by rearing them in two photoperiods. In both species, diurnal foraging ceased at large sizes while nocturnal foraging remained constant or increased, thus larvae showed ontogenetic shifts in behaviour. Short night lengths forced small individuals to take higher risks and forage more during daytime, postponing the shift to strict night foraging to later on in development. In the non-seasonal species, seasonal time stress had a small effect on development and the diurnal–nocturnal foraging mode. In contrast, in the seasonal species, time for pupation and the timing of the foraging shift were strongly affected. We argue that a large part of the observed variation in larval diurnal–nocturnal activity and resulting growth rates is explained by changes in the cost/benefit ratio of foraging mediated by size-dependent predation and time stress.     

An Assessment of U.S. Stream Compensatory Mitigation Policy: Necessary Changes to Protect Ecosystem Functions and Services

Compensatory mitigation of impacted streams and wetlands has increased over the past two decades, with the associated industry spending over US$2.9 billion in aquatic restoration annually. Despite these expenditures, evaluations by the National Research Council and U.S. Government Accountability Office have provided evidence that compensatory mitigation practices are failing to protect aquatic resource functions and services, and vague federal policy and inadequate evaluation of compensatory mitigation projects are to blame. To address these weaknesses, an update to federal regulations on compensatory mitigation was released in 2008. Additionally, the 2012 Reissuance of Nationwide Permits, some of which affects compensatory stream mitigation, was recently published. Current policy, as reflected in these documents, still uses nonspecific language to direct compensatory stream mitigation leaving most implementation decisions to the local U.S. Army Corps of Engineers district. The majority of federal mitigation policy has focused on wetland compensation, with other aquatic resources receiving less attention (e.g., streams). In this article, weaknesses of current policy are discussed, as are suggested policy changes to minimize the loss of stream ecosystem functions and services. Compensatory mitigation policy should clearly define key terms, incorporate adaptive management procedures, and provide guidelines for determining mitigation costs and compensation ratio requirements.     

STATE LEGISLATIVE CONSTRAINTS ON THE DEVELOPMENT OF WATER RESOURCES POLICY1

ABSTRACT: Legislative constraints on the development of water resources policy fit into three broad categories-political, institutional, and informational. The political category encompasses constituency needs and preferences, satisfaction with existing water management practices and policies, and the necessity for legislators to blend political ambition with public problem solving. Constraints fitting into the institutional category include differences in legislative behavior and attitudes that stem from one's location in the legislature (e.g., senate-house, leader-follower, or committee activity), the dynamics of scheduling and organization, and the capability to manage complex issues. Informational constraints refer to the availability of information and the use to which it is put by lawmakers in formulating decisions on waterrelated issues. These constraints are approached from a behavioral perspective by examining several constituency, institutional, and information hypotheses that “explain” legislative involvement with water resources issues. The data are drawn from a recent study of water resources decision making in West Virginia. Eighty-three of the 134 members of the 1975–76 West Virginia Legislature participated in the study.     

考虑优先权的人群安全疏散动态模型

为制定合理、高效的应急状况下建筑物内人群疏散方案,考虑拥堵对人流速度的影响及疏散中不同人员特点,对建筑物内人群疏散动态实时分配问题进行研究。首先,采用元胞传输理论将建筑物内复杂的结构转化为元胞—连接桥路网模型,进而以最短疏散时间为目标函数、元胞流量守恒和流量传播为约束条件建立线性优化模型。通过对模型的求解可以得到不同优先级人员的网络清空时间、各路段实时人员数量及路径选择最优方案。案例分析结果表明,疏散过程中人员的优先级差异以及拥堵的发生均会影响不同人员的网络清空时间,因此,针对建筑物内人群疏散进行建模时,应考虑以上因素。     

系统动力学模型在城市发展规划环评中的应用

鉴于作为评价对象的城市社会经济环境复合系统具有多目标、多要素、动态关联等突出的系统动力学特征,选择和应用系统动力学方法开展城市发展规划环评在理论上具有可行性和技术优势.作为典型资源型城市的山西省临汾市正面临转变发展方式和加快环境治理的紧迫要求,本文依托该市转型发展规划环评工作,在全面识别和剖析城市发展要素、现状问题及其成因基础上,以经济发展、产业结构、节能减排和环境改善为重点研究了规划要素间的动态反馈关系,以此构建城市转型发展规划环评SD模型,并对4个规划替代方案进行模拟和评价.结果显示,在环境目标刚性约束下所有替代方案均不能实现人均GDP翻番的较高经济增长目标,其中以较强环境约束为特征的“方案III”具有最好的环境与经济综合效果.据此评价建议临汾市应在确保实现环境改善目标的前提下主动放缓工业增长速度,同时加快以“煤焦铁电”为代表的主导产业结构调整并继续加大节能减排力度,全面提高城市可持续发展能力.     

全球碳排放权分配与减排分担研究——基于环境约束与公平感受的视角

排放权分配与减排分担始终是国际气候治理的关键问题,基于2℃环境约束与公平感受视角,利用多原则综合加权的分配方法,对全球排放权分配与减排分担展开研究,其结论如下:(1)在温升控制目标下,全球年均排放空间为177.42亿t;满足公平感受要求的全球年均配额为207.59亿t;以2015年实际排放为例,全球年均贡献减排与责任减排分别为30.17亿t、120.42亿t。(2)应用六大单一原则的排放权配额分配,其结果相差悬殊;发达国家和地区普遍偏好等产出原则,发展中国家和地区偏好排放责任原则;基于公平感受的综合加权分配方案降低了单一原则分配的规则"刚性",能缓解分配中的"南北"失衡现象。(3)减排分担结果显示,分担集中于少数Ⅰ类地区的国家和地区,而大多数Ⅴ类地区的国家和地区减排分担不高,当前全球仍处于责任减排阶段。因此,排放权分配要在公平与可行、总量目标与个体标准之间寻求平衡,充分挖掘减排潜力;减排分担应坚持两个区分,减排目标实现按三阶段渐进。     

基于STPA法的空中加油软管甩鞭安全性分析

为定量评价空中加油软管甩鞭(HWP)现象的安全性,使用系统理论过程分析(STPA)法查找出相关系统级危险、不安全控制行为和致因因素共计46条,确定与之对应的44项安全对接约束条件;依据空中加油飞行试验数据,定义可量化的安全检查点,依据安全检查点将安全约束条件分为17类,确定各检查点的安全区间和权重;根据飞行数据确定HW...