Discounting for personal and social payments: Patience for others,impatience for ourselves

The market rate of return on private investment is often used as the discount rate when conducting cost-benefit analysis (CBA) of public projects. I argue that the decision to invest pits current consumption against future consumption, both of which accumulate to the private decision maker. Public projects, on the other hand, provide benefits that accrue to society in general. To examine the appropriateness of discount rates based on returns to private investment, this paper considers lab experiments designed to test whether individuals discount personal and social benefits at different rates. Personal benefits are captured through personal monetary payments, while social benefits are captured through anonymous donations to charitable organizations. I jointly elicit time and risk preferences and find that subjects discount charitable contributions at significantly lower rates than personal payments.     

质子交换膜燃料电池电站多米诺事故概率和风险研究

为探究氢能电站火灾爆炸事故发展规律,采用多米诺效应对电站进行事故概率和风险研究,建立氢能电站多米诺效应定量风险分析模型。基于设备受损概率模型与多米诺理论基础,提出氢能电站多米诺效应概率计算方法,并将方法运用到实际案例,结合SAFETI软件对具体多米诺事故场景进行定量计算。研究结果表明：氢能电站易发生多米诺事故,考虑一级多米诺效应后人员潜在死亡概率增加56%。研究结果可为制定氢能电站安全防控措施以及降低火灾爆炸事故对人员和设备的危害提供依据。     

Dynamic risk assessment using failure assessment and Bayesian theory

To ensure the safety of a process system, engineers use different methods to identify the potential hazards that may cause severe consequences. One of the most popular methods used is quantitative risk assessment (QRA) which quantifies the risk associated with a particular process activity. One of QRA's major disadvantages is its inability to update risk during the life of a process. As the process operates, abnormal events will result in incidents and near misses. These events are often called accident precursors. A conventional QRA process is unable to use the accident precursor information to revise the risk profile. To overcome this, a methodology has been proposed based on the work of Meel and Seider (2006). Similar to Meel and Seider (2006) work, this methodology uses Bayesian theory to update the likelihood of the event occurrence and also failure probability of the safety system. In this paper the proposed methodology is outlined and its application is demonstrated using a simple case study. First, potential accident scenarios are identified and represented in terms of an event tree, next, using the event tree and available failure data end-state probabilities are estimated. Subsequently, using the available accident precursor data, safety system failure likelihood and event tree end-state probabilities are revised. The methodology has been simulated using deterministic (point value) as well as probabilistic approach. This Methodology is applied to a case study demonstrating a storage tank containing highly hazardous chemicals. The comparison between conventional QRA and the results from dynamic failure assessment approach shows the significant deviation in system failure frequency throughout the life time of the process unit.     

基于Copula函数的泾河流域水沙关系演变特征分析

为了掌握泾河流域水沙演变规律,基于张家山水文站1956-2010 年径流与输沙量数据,采用滑动平均法分析流域水沙变化,提出应用滑动相关系数法诊断水沙关系变异,与双累积曲线法相互验证,选取皮尔逊III 型分布拟合变异前后水沙分布,基于Copula 函数建立水沙联合分布,对比分析泾河流域水沙变化特征,研究不同时段水沙丰枯遭遇情况.结果表明:① 水沙关系于20 世纪80 年代发生变异;② 以1982 年为分割点,相比于1956-1982 年,1983-2010 年水沙均值减小,设计频率P≤90%时水沙值均减小,P >90%时,径流减小,输沙量增加;③ 两阶段水沙丰枯同步频率大于丰枯异步频率,“水丰沙枯或水枯沙丰”遭遇组合概率最小,变异后时段(1983-2010 年)各种遭遇组合频率分布更为均匀,水沙丰枯异步频率变大.     

关于河流纳污混合水质概率稀释模型及其应用研究

本文以淮河干流上游息县和维滨两个城关纳污河段为例,根据扩散理论和概率学理论,尝试建立了河流纳污混合水质浓度概率稀释模型。并研究确定了概率稀释模型在河流污染控制中的应用方法和技术路线。与实测结果比较,概率稀释模型方法计算更具有准确性和科学合理性．对水质评价和规划河流污染治理方案具有重要指导意义,对实现淮河水质返清目标有积极贡献。     

基于环境空气中VOCs在线监测数据精准识别化工园区VOCs排放源

为精准识别化工园区环境空气VOCs排放源, 2017年1月基于连续在线GC-FID法逐时监测某化工园区5个点环境空气中43种VOCs数据,运用统计分析法和PMF模型识别其来源,再结合CPF方法和企业排放信息达到精准化识别各排放源.结果表明, 5个监测点平均VOCs体积分数为56.40×10^-9,除一个点其余点均以烷烃含量最高,主要是乙烷、丙烷、乙烯、甲苯、异丁烷、正丁烷和乙炔;园区环境空气中VOCs来自丁烷泄漏、工艺过程中排放、储罐排放、乙烯合成和城区传输这5个来源;基于气象传输路径分析和企业排放信息,识别出园区有7家化工企业以及园区外运河装卸区是观测期间VOCs的主要排放源.本研究以在线监测数据为基础,联合受体模型、气象条件及企业排放信息,实现了化工园区内VOCs污染来源的精准化定位,为园区内企业排放的监督和管理提供依据.     

Quantifying the probability of detection of wild ungulates with the Judas technique

The Judas technique is often used in control or eradication of particular vertebrate pests. The technique exploits the tendency of individuals to form social groups. A radio collar is affixed to an individual and its subsequent monitoring facilitates the detection of other conspecifics. Efficacy of this technique would be improved if managers could estimate the probability that a Judas individual would detect conspecifics. To calculate this probability, we estimated association rates of Judas individuals with other Judas individuals, given the length of time the Judas has been deployed. We developed a simple model of space-use for individual Judas animals and constrained detection probabilities to those specific areas. We then combined estimates for individual Judas animals to infer the probability that a wild individual could be detected in an area of interest via Judas surveillance. We illustrated the method by using data from a feral goat eradication program on Isla Santiago, Galápagos, and a feral pig eradication program on Santa Cruz Island, California. Association probabilities declined as the proximity between individual areas of use of a Judas pair decreased. Unconditional probabilities of detection within individual areas of use averaged 0.09 per month for feral pigs and 0.11 per month for feral goats. Probabilities that eradication had been achieved, given no detections of wild conspecifics, and an uninformative prior probability of eradication were 0.79 (90% CI 0.22–0.99) for feral goats and 0.87 (90% CI 0.44–1.0) for feral pigs. We envisage several additions to the analyses used that could improve estimates of Judas detection probability. Analyses such as these can help managers increase the efficacy of eradication efforts, leading to more effective effects to restore native biodiversity.     

异常环境下要害系统确信安全评估方法

目的 获得异常环境下的要害系统确信安全评估(PLOAS)建立评估方法和技术框架,为要害系统安全性设计和安全防护决策提供科学支撑.方法 基于要害系统在异常环境条件下结构响应行为机制,以表征安全性的响应特征参数为对象,融合试验、数值仿真等技术手段以及代理模型构建等不确定性分析方法,通过定量计算安全特征参数未达到失效阈值的概...