Optimization Model and Algorithm for Crew Management During Airline Irregular Operations

Airline irregular operations have long been a realm where human experience and judgement are the most important tools to utilize. Crew management during irregular operations is usually the bottleneck of the whole system-recovering process due to complicated crew schedules and restrictive crew legalities as well as the size and scope of the hub-and-spoke networks adopted by major carriers. A system-wide multi-commodity integer network flow model and a heuristic search algorithm for the above purpose are presented and discussed in this paper. The computational experiences show that the algorithm is efficient enough to solve problems of realistic size and also has the flexibility to accommodate practical business requirements.     

Compliance Versus Risk in Assessing Occupational Exposures

Assessments of occupational exposures to chemicals are generally based upon the practice of compliance testing in which the probability of compliance is related to the exceedance [γ, the likelihood that any measurement would exceed an occupational exposure limit (OEL)] and the number of measurements obtained. On the other hand, workers’ chronic health risks generally depend upon cumulative lifetime exposures which are not directly related to the probability of compliance. In this paper we define the probability of “overexposure” (θ) as the likelihood that individual risk (a function of cumulative exposure) exceeds the risk inherent in the OEL (a function of the OEL and duration of exposure). We regard θ as a relevant measure of individual risk for chemicals, such as carcinogens, which produce chronic effects after long-term exposures but not necessarily for acutely-toxic substances which can produce effects relatively quickly. We apply a random-effects model to data from 179 groups of workers, exposed to a variety of chemical agents, and obtain parameter estimates for the group mean exposure and the within- and between-worker components of variance. These estimates are then combined with OELs to generate estimates of γ and θ. We show that compliance testing can significantly underestimate the health risk when sample sizes are small. That is, there can be large probabilities of compliance with typical sample sizes, despite the fact that large proportions of the working population have individual risks greater than the risk inherent in the OEL. We demonstrate further that, because the relationship between θ and γ depends upon the within- and between-worker components of variance, it cannot be assumed a priori that exceedance is a conservative surrogate for overexposure. Thus, we conclude that assessment practices which focus upon either compliance or exceedance are problematic and recommend that employers evaluate exposures relative to the probabilities of overexposure.     

Minimum power assignment in wireless ad hoc networks with spanner property

Power assignment for wireless ad hoc networks is to assign a power for each wireless node such that the induced communication graph has some required properties. Recently research efforts have focused on finding the minimum power assignment to guarantee the connectivity or fault-tolerance of the network. In this paper, we study a new problem of finding the power assignment such that the induced communication graph is a spanner for the original communication graph when all nodes have the maximum power. Here, a spanner means that the length of the shortest path in the induced communication graph is at most a constant times of the length of the shortest path in the original communication graph. Polynomial time algorithm is given to minimize the maximum assigned power with spanner property. The algorithm also works for any other property that can be tested in polynomial time and is monotone. We then give a polynomial time approximation method to minimize the total transmission radius of all nodes. Finally, we propose two heuristics and conduct extensive simulations to study their performance when we aim to minimize the total assigned power of all nodes. The author is partially supported by NSF CCR-0311174.     

经济收敛理论与检验方法研究综述

在大量文献研究的基础上,对收敛问题的产生及收敛概念的发展作了全面概括,并对绝对收敛、条件收敛、俱乐部收敛和σ收敛作了深入辨析,对各种识别方法作了全面归纳。归纳了对世界大多数国家和地区数据所作识别的结果。还从收敛理论与传统理论的冲突与协调方面作了深入分析。最后对近年收敛研究的深化与扩展研究的趋势作了概括。     

美国、欧盟计算机软件相关发明的专利保护比较研究

分别从计算机软件相关发明专利保护的立法、判例法的发展和演变、专利申请审查实践准则等方面出发,对美国和欧盟计算机软件相关发明的专利保护进行了对比分析,总结出两者现行司法和审查实践中的一致和分歧,以及各自的优劣,从而获得对中国的启示。     

延迟决策对一类产出系统演化的影响研究

企业作为有限理性的经济主体,在做下阶段的生产决策时可能不仅考虑本期而是要综合考虑以往连续多期的边际利润情况。研究表明,加入时滞以后,系统纳什平衡点的稳定域明显扩大,从而为在混沌经济系统中实现倍周期分岔控制提供了现实途径,同时,还会使系统在纳什平衡点出现hopf分岔等新的动力学演化行为。而且,以累积利润为指标的系统表现可以得到改善。首先引入延迟决策的企业将获得更大的相对竞争优势。而在两家企业都引入延迟决策的情况下,伴随第二家企业产量调整速度的增加,它们将交替获得竞争优势。     

西部山区农民易地扶贫搬迁意愿的影响因素

从现在到2020年是打赢脱贫攻坚战的关键时期,从农民自身角度研究搬迁意愿,对加快实施易地扶贫移民搬迁具有重要意义。研究依据西方微观人口迁移理论：地方效用理论、计划行为理论和效价[CD*2]期望理论,整合构建了中国国情下由政府引导的易地扶贫搬迁意愿的理论分析框架。以陕南移民搬迁为例,在验证性因子分析的基础上,运用有序Logit模型和最优尺度模型对理论假设进行检验。结果显示：①心理因素、政策和预期因素、环境因素对搬迁意愿具有显著影响 ②控制变量中家庭人口数、非农劳动力比例、家庭成员求学婚姻等控制变量与搬迁意愿显著相关;③没有搬迁的主要的顾虑是搬迁后找不到工作、城镇生活成本高、搬迁成本高、搬迁后的适应等问题。研究建议政府部门在搬迁补助、就业安置、搬迁后适应等方面加大支持力度,增强搬迁的信心。     

澳门社区治理模式的特征及启示

本文从治理主体和治理路径入手分析澳门治理模式的突出特征,研究发现澳门政府、社区组织和居民组成的治理主体权责分明、各尽其事,运用社会工作、公民教育和咨询协商等治理路径为澳门社区居民构建美好家园、和谐社区,这些突出特征为反思中国大陆社区治理主体多元化和治理路径有效性提供重要参考.     

中国西部地区小额贷款的实效分析——基于实证分析

通过对客户的家庭收入、家庭消费、家庭净资产衡量小额信贷在改善客户福利效率的实证分析中发现,小额信贷在农村客户福利改善方面,对农村客户的促进效率高于其他两类客户,一方面农村客户使用小额信贷的效率相对较高,另一方面农村客户获得小额信贷数额较少,最终导致农村客户与乡镇客户、村镇两栖客户福利差距依然明显.为此,本文提出:小额贷款应配合"精准扶贫"政策,实行"精准贷款".     

为了真实和正义的历史重述——论何顿的《黄埔四期》

《黄埔四期》重述了自北伐至“文革”后这半个多世纪以来的中国历史,力图以文学的方式祛除政治对历史的遮蔽,挖掘那些被隐没的史实;用传奇的笔法展示那些被历史埋没的英雄,再现中华民族伟大的抗战史, 还民族英雄以应有的尊重。