Distributions of ratios of random variables from the power-quadratic exponential family and applications

We derive the closed form exact expression of the density of the ratio X ₁/X ₂, where X ₁ and X ₂ are independent and belong to the very versatile family of power-quadratic exponential distributions. The case of X ₂ as a gamma variable is studied in detail, and new applications found in different domains show the varied uses of the results presented.     

工业化过程中碳排放消费建设比的演变规律研究

本文从历史发展角度动态地考察了由投资和消费引发CO₂排放的变化规律,提出了碳排放中的消费型排放、建设型排放和消费建设比的概念,利用环境投入产出分析模型(EE-IOA)估计了处于不同工业化发展阶段的32个国家86组数据的消费型排放和建设型排放,得到了消费建设比在工业化过程中(包括后工业化时期)的演变规律。实证结果表明:随着工业化水平的提高,消费建设比呈上升趋势;应根据消费型排放和建设型排放的减排潜力,科学制定减排目标,更加注重引导消费者行为向绿色消费转变、依靠消费者力量促进企业节能减排。本研究对正确评价不同工业化发展阶段国家的排放水平和减排潜力,科学制定减排政策和目标具有重要意义。     

Analysis of Travel Times and CO2 Emissions in Time‐Dependent Vehicle Routing

Due to the growing concern over environmental issues, regardless of whether companies are going to voluntarily incorporate green policies in practice, or will be forced to do so in the context of new legislation, change is foreseen in the future of transportation management. Assigning and scheduling vehicles to service a pre‐determined set of clients is a common distribution problem. Accounting for time‐dependent travel times between customers, we present a model that considers travel time, fuel, and CO₂ emissions costs. Specifically, we propose a framework for modeling CO₂ emissions in a time‐dependent vehicle routing context. The model is solved via a tabu search procedure. As the amount of CO₂ emissions is correlated with vehicle speed, our model considers limiting vehicle speed as part of the optimization. The emissions per kilometer as a function of speed are minimized at a unique speed. However, we show that in a time‐dependent environment this speed is sub‐optimal in terms of total emissions. This occurs if vehicles are able to avoid running into congestion periods where they incur high emissions. Clearly, considering this trade‐off in the vehicle routing problem has great practical potential. In the same line, we construct bounds on the total amount of emissions to be saved by making use of the standard VRP solutions. As fuel consumption is correlated with CO₂ emissions, we show that reducing emissions leads to reducing costs. For a number of experimental settings, we show that limiting vehicle speeds is desired from a total cost perspective. This namely stems from the trade‐off between fuel and travel time costs.     

The black earnings gap: discrimination or culture

This paper explores the earnings gap between West Indians and African Americans that cannot be explained by observable characteristics and is often interpreted as a measure of discrimination or unobservable cultural endowments. The earnings gap advantage has lead to many perceptions and some unsubstantiated implications as to the reasons why West Indians perform better than African Americans in the labor market. This is an attempt to sort out the implications and to put the West Indian/African American earnings difference in prospective.     

第二代保险偿付能力监管体系建设初探

2008年金融危机的爆发全面呈现了现行保险偿付能力监管制度体系的不足。我国第一代保险偿付能力监管体系的不足为：对保险公司治理和内部风险控制等偿付能力的影响没有加以考察;对保险公司不同险种偿付能力的要求采取不科学的统一模式;没有对保险公司面临的风险全面评估;没有对分支机构的有力监管;规定不协调、空白和不符合国情的问题。应在合理设计第二代偿付能力监管体系风险识别类型的基础上,实现偿付能力监管体系结果与过程的统一;加强对综合金融保险集团的资本充足率监管;改革现行监管体系不合国情、不协调的问题并弥补监管空白。     

乡村生态的审美性书写——中西文学比照下的赛珍珠农村题材小说

赛珍珠的中国农村题材小说提供了一种文学范本,使中国现代乡土小说多了一份同＂题材＂而异＂表现＂的观照,其艺术化、审美性的中国乡村生态实录,在一定程度上弥补了中国乡土作家作品中乡村原生态意蕴不足的缺陷,给中国作家以启迪,因此,有必要对赛氏小说和中国现代作家的＂乡土小说＂进行详细的比较,以期明晰异质文化对照下文学文本的不同表现,进而促进中西方读者对赛珍珠小说的认知。     

虚实相间 相得益彰——试论赛珍珠小说创作策略

赛珍珠＂中国意象＂的书写方式始终游离于文学的虚构与历史的真实之间。就其真实性而言,赛氏笔下的＂中国意象＂书写是其以亲历者身份审视传统与近代中国文化的结果;而就其虚构性来看,这种书写却又不断增强了其作品的文学性、艺术性和可读性,奠定了她在世界文学的重要地位。赛氏的＂中国意象＂书写让读者游走在真实与虚构、宏观与微观、严肃与想象的小说叙事之中。这种叙事方式使我们能更好地理解这位世界公民所坚持的多元对话和沟通思想,并能从中体会她对中国当时社会各个层面的深切关注。     

基于最大偏差原则的群体性事件应急管理绩效评价模型

群体性突发事件应急管理绩效评价具有价值判断冲突性、结构嵌入性和语义模糊性等非常规特征。针对群体性突发事件的矛盾对抗性特征,根据"着重解决群众反映意见较大的突出问题"的善后处置原则,构建了基于最大偏差原则的多属性评价模型。首先,在社会结构、应急策略和评价指标等多重维度下,构建了件应急管理绩效评价指标体系,包括效率、公平、收敛性、稳定性和适应性。其次,针对价值判断冲突特征,提出基于最大偏差原则的二元语义信息处理方法:偏差越大,表明该属性能够更好的反映出事态冲突性,应赋予越高的权重。最后,结合某住宅小区锅炉房拆迁案例的全样本调查数据进行实证分析。结果表明,相对于模糊综合评价模型和最小偏差原则的二元语义模型,基于最大偏差原则更能反映出群体性突发事件应急管理绩效评价的价值冲突性。     

广东入境旅游规模差异及其演变趋势研究

文章以广东省21个地市的2002－2013年共12年的入境旅游人数为样本数据,运用位序规模理论,标准差( VOC)、基尼系数( G)以及赫芬达尔系数( Hn)等计量指标,以及分形理论的R/S分析法依次分析了广东省入境旅游规模分布现状、区域差异化程度及未来入境旅游规模的演化趋势,得知广东省入境旅游规模呈高度首位型分布、区域间差异化较为明显且集聚程度下降,其入境旅游规模将在未来一段时间内持续扩大。     

A Simultaneous Confidence Band for Dense Longitudinal Regression

We present a method of using local linear smoothing to construct simultaneous confidence bands for the mean function of densely spaced functional data. Our approach works well under mild conditions. In addition, the local linear estimator and its accompanying confidence band enjoy semiparametric efficiency in the sense that they are asymptotically equivalent to the counterparts obtained from the random trajectories entirely observed without errors. We illustrate the performance of the proposed confidence band through a simulation study. Furthermore, an application in food science is presented.