基于GSPABN的拓扑结构系统状态动态分析

介绍了贝叶斯网络(BN)应用现状及其优势,引入GSPA理论,提出了基于GSPA-BN拓扑结构节点状态分析模型,讨论了节点状态联系度及其重要度表示方法,提出了BN拓扑结构节点态势概念。结果表明,以构建的锅炉缺水烧干事件的BN拓扑结构为例,得到了各根节点重要度排序;同时得到了叶节点、中间节点状态联系度及其态势等级,且中间状态的变化会对其节点态势及其等级产生一定的影响,甚至发生节点态势逆转现象,为动态了解BN拓扑结构节点态势发展奠定了理论分析依据。     

基于贝叶斯网络的非正常情况下高铁行车调度人因可靠性分析

行车调度子系统在整个高铁运输系统中处于关键位置,虽然行车调度大多已经采用了信息化、自动化的作业程序,但发生设备故障、交通事故、自然灾害等非正常情况时,很多具体的作业组织和管理仍需行车调度作业人员的参与.提出了一种基于贝叶斯网络考虑情境环境因子交互关系的人因可靠性分析方法,以某铁路局的人因失误数据统计表为学习样本,推理出行车调度作业人员工作中存在的主要问题.结果表明,“完成任务的可用时间”、“培训”及“人员配置”的节点状态变化会对作业人员的可靠性产生很大影响.最后,以高铁行车调度人员在某种特定情境状态下的实际作业为例进行了实证研究.研究表明,所建立的方法正确可靠,能够准确、高效地辨识人因可靠性.     

滇池流域TN、TP入湖负荷预报预警系统

以流域模型HSPF和贝叶斯递归回归树算法(BRRT)为计算模块,建立了滇池流域27条主要入湖河流和33个散流区的TN、TP入湖负荷预报预警系统.同时,构建了考虑历史排放规律和预测负荷计算预警指数(EWI)评价预警等级的两套预警体系.结果表明:BRRT替代模型在流域内以农业面源为主的柴河子流域校准和验证的可决系数R2均大于0.8,模拟结果相对可靠;根据预警时间选取预警体系;适用于6月份之前的预警体系一(EWS-1),利用现状排放量和历史排放量的关系计算预警指数.适用于6月份之后的预警体系二(EWS-2),主要考虑现状排放量、历史平均排放量、排放限值和预测排放量之间的关系计算3个预警指数,最终以最严格的作为综合预警指数EWI评价预警等级;根据柴河子流域"十二五"规划的TN和TP排放限值为130.2 t·a-1、6.8 t·a-1,应用此系统对2011年2、4、9和11月做出预警检验,各月份预警结果基本处于红色和黑色预警,该系统可为流域提供预警支持.     

Risk assessment of rare events

Rare events often result in large impacts and are hard to predict. Risk analysis of such events is a challenging task because there are few directly relevant data to form a basis for probabilistic risk assessment. Due to the scarcity of data, the probability estimation of a rare event often uses precursor data. Precursor-based methods have been widely used in probability estimation of rare events. However, few attempts have been made to estimate consequences of rare events using their precursors. This paper proposes a holistic precursor-based risk assessment framework for rare events. The Hierarchical Bayesian Approach (HBA) using hyper-priors to represent prior parameters is applied to probability estimation in the proposed framework. Accident precursor data are utilized from an information theory perspective to seek the most informative precursor upon which the consequence of a rare event is estimated. Combining the estimated probability and consequence gives a reasonable assessment of risk. The assessed risk is updated as new information becomes available to produce a dynamic risk profile. The applicability of the methodology is tested through a case study of an offshore blowout accident. The proposed framework provides a rational way to develop the dynamic risk profile of a rare event for its prevention and control.     

基于贝叶斯网络情景分析的含水土质埋压救援现场监测体系研究*

为提高含水土质埋压救援现场救援效率,基于贝叶斯网络进行情景推演分析,明确典型不利情景演化路径和关键节点,构建多方位多因素耦合的含水土质埋压监测体系。研究结果表明:基于贝叶斯网络情景分析的含水土质埋压救援现场监测体系将灾害环境监测、救援人员状态监测、埋压人员状态监测、救援设备状态监测、整体救援进展跟踪监测划分为18个监测单元,明确土质压力等11个关键监测参数及其技术手段。研究结果可有效提高救援行动安全性,为含水土质埋压救援现场安全监测系统研发提供理论支撑。     

Integrating flare gas with cogeneration systems: Operational risk assessment

Flare gas utilization in a cogeneration plant is an attractive proposition considering its environmental and economic incentives. Evaluation of the operational risk of integrating flare gas with cogeneration is complex due to the uncertainty in flare gas quality and process conditions. The current study delves into the change in operational risk after modifying the existing cogeneration process with the addition of fuel from flare gas. Based on the process hazards evaluation, the current study identified two critical loss control events (or top events) - boiler gas temperature exceeding operating design temperature and rich fuel mixture in the boiler firebox. The underlying causes that may contribute and lead to these loss control events were identified using fault trees and were updated to the existing cogeneration scenarios. Similarly, different consequential events that may arise from the loss control events were analysed using event trees with existing system safeguards. A Bayesian network model with its explanatory power mapped all the identified dangerous scenarios from the fault trees and event trees to predict integrated systems reliability and diagnose causal factors. Bayesian Network analysis illustrates the dynamic cause-effect relationship and determines the risk escalation due to the changes in the composition of flare gas that is fed to the boiler. The presence of a higher percentage of hydrogen (above 40 mol%) in the flare gas escalates the risk of lean air to fuel ratio in the boiler firebox and increases boiler radiation zone duty. These conditions are detrimental to the boiler firebox operation and can result in critical scenarios such as flame impingement and tube rupture. Additionally, other consequences-a steam explosion and boiler stack explosion were also investigated. However, their probability of occurrence was relatively insignificant with the given frequency of flare gas utilization in the cogeneration system.     

基于贝叶斯随机评价方法的小城镇灾害易损性分析

为了准确评价小城镇灾害易损性所处的状态,进而为制定小城镇防灾减灾规划提供科学依据,提出了基于贝叶斯公式的小城镇灾害易损性随机评价方法。该方法通过计算小城镇灾害易损性单个指标属于某个评价级别的概率,由最大似然分类原则确定单个易损性指标的评价级别,进而采用最大加权概率原则推求其综合评价级别。通过实例计算分析,并与模糊评估方法、可拓物元评价方法进行比较验证,说明了该方法的可行性及其简单、实用的特点。     

Bayesian spatial prediction

This paper presents a complete Bayesian methodology for analyzing spatial data, one which employs proper priors and features diagnostic methods in the Bayesian spatial setting. The spatial covariance structure is modeled using a rich class of covariance functions for Gaussian random fields. A general class of priors for trend, scale, and structural covariance parameters is considered. In particular, we obtain analytic results that allow easy computation of the predictive distribution for an arbitrary prior on the parameters of the covariance function using importance sampling. The computations, as well as model diagnostics and sensitivity analysis, are illustrated with a set of precipitation data.     

Bayesian estimation of European sulphur emissions using monitoring data and an acid deposition model

A statistical method for estimating national emissions of acidifying air pollutants in Europe is presented. The method uses an acid deposition model to match official emissions data from European countries and measured depositions from a monitoring network. An application to 1990 sulphate data demonstrates the method and suggests some tendencies in the reported emissions. The proposed framework may prove useful for verifying national compliance with emissions standards, and the method should be applicable also to other substances than sulphur dioxide. The problem of designing an optimal monitoring network may also be assessed within the proposed statistical framework.     

中国环境影响评价制度四方信号博弈分析

针对中国环境影响评价执行率逐步提高的同时,环境质量却持续恶化的现状,从环境经济学的理论出发,揭示了参与方之间的关系是由其经济关系决定的,取决于参与方之间的交易成本和经济收益.选用经典博弈论中的信号博弈模型对中国的环评过程进行描述,分析参与四方(政府、企业、环评单位、公众)的行动,得出博弈均衡解,按照博弈的转化条件,获得将现有均衡转变为最优均衡状态的博弈方法.分析发现,模型存在2个均衡解.目前的环境影响评价处在片面追求经济收益的状态,而追求经济和环境保护协调发展的状态,显然更符合社会发展的要求.在将公众作为参与方加入到模型后,通过计算模型总收益和总成本的变化,表明完善的公众参与体制可以实现模型均衡转化的目标.