考虑多重不确定性的我国多层#br# 冷成型钢结构地震风险评估

准确评估建筑结构的地震风险是实现其性能化抗震设计的重要组成部分。冷成型钢结构体系作为绿色和工业化建筑的典型代表,却鲜有针对于我国的地震风险评估研究。文章旨在分析和评估多层冷成型钢结构抗震分析所涉及的多重不确定性因素,进而定量评估该类结构在我国的地震风险。文章设计1栋八度抗震设防的6层冷成型钢结构,基于经过振动台验证的简化数值分析方法建立结构的简化数值模型,定量求解结构的多重不确定性因素和在使用周期内(50年)的地震风险。研究结果表明：由于我国一些地区的地震危险性形状系数较大,在考虑多重不确定性后,结构的破坏概率显著提高,50年使用周期内倒塌概率的增幅达到10倍以上;算例结构在50年使用周期内基本满足“小震不坏、中震可修、大震不倒”的抗震设防要求,对于个别特殊区域应适当控制结构发生轻微破坏的概率。此外,文章建议应全面考虑多重不确定对冷成型钢结构地震风险的影响,对不确定性参数的取值和地震风险的计算方法可提供借鉴。     

Risk assessment of exposure to volatile organic compounds in groundwater in Taiwan

The purpose of this study is to assess the risks from exposure to 14 volatile organic compounds (VOCs) in selected groundwater sites in Taiwan. The study employs the multimedia environment pollutant assessment system (MEPAS) model to calculate the specific non-cancer and cancer risks at an exposure level of 1 μg/L of each VOC for a variety of exposure pathways. The results show that the highest specific non-cancer risk is associated with water ingestion of vinyl chloride (VC) and that the highest specific cancer risk is associated with indoor breathing of VC. The three most important exposure pathways for risk assessment for both non-cancer and cancer risks are identified as water ingestion, dermal absorption when showering, and indoor breathing. Excess tetrachloroethylene (PCE), trichloroethylene (TCE), dichloroethylene (DCE), and VC are detected in the groundwater aquifers of one dump site and one factory. However, the study suggests that the pollutants in the contaminated groundwater aquifers do not travel extensively with groundwater flow and that the resulting VOC concentrations are below detectable levels for most of the sampled drinking-water treatment plants. Nevertheless, the non-cancer and cancer risks resulting from use of the contaminated groundwater are found to be hundred times higher than the general risk guidance values. To ensure safe groundwater utilisation, remediation initiatives for soil and groundwater are required. Finally, the study suggests that the current criteria for VOCs in drinking water might not be capable of ensuring public safety when groundwater is used as the primary water supply; more stringent quality criteria for drinking water are proposed for selected VOCs.     

Organic micropollutants in drinking water: An overview

Biological contamination is still the most significant public health risk from drinking water even in industrialized countries. High potential for organic chemical transport to drinking water continues to exist even with source protection because of the multitude of chemical types and quantities. Drinking water is usually not a unique source nor the most significant contributor to total exposure from synthetic organic chemicals but it might be one of the most controllable.The major public concern with drinking water contamination has been possible contribution to cancer risks from organic micropollutants. Even though the actual risks are probably small in most cases it is clearly within the public interest to prevent adulteration of water supplies and to protect their quality for the future so that these concerns or risks can be avoided.A risk assessment/management decision model is suggested which may assist the process of making rational assessments of these contamination problems and control decisions that consciously consider all of the available data in a consistent manner.     

Risk analysis in ultra deep scientific drilling project — A fuzzy synthetic evaluation approach

Exploration of deep earth requires ultra deep drilling attempts on the sea or continent, which is the main goal of scientific drilling projects currently established. Uncertain geological complexity, high requirement for R&D of critical equipment as well as high demand of practical performance has to be encountered during a scientific drilling project, making it full of challenge and risks. Risk management, therefore, is critically proposed for scientific drilling projects in order to reduce the risks. However, many traditional risk assessment methods may not perform well in the project due to lack of high quality data of historical record and sufficient information. This paper, therefore, proposes a fuzzy synthetic evaluation approach for scientific drilling project risk assessment. Four criteria — probability, severity, non-detectability and worsening factor are utilized to evaluate individual and overall risks comprehensively. Linguistic terms instead of numerical values are employed to evaluate each risk normally done by experts. AHP/ANP is used to determine sensible weights of each criterion. Values of risk indices are calculated to represent the level of each risk and the overall risk. Finally, a case study on risk analysis of SinoProbe-09 project conducted in Jilin University is tested to demonstrate the procedure of the method and to validate the proposed method. Results show that the risks of the scientific drilling project can be assessed effectively and efficiently.     

Regional assessment of ambient volatile organic compounds from biopharmaceutical R&D complex

Biopharmaceutical R&D complexes are major emission sources of volatile organic compounds (VOCs), which may pose potential health risks for staff on site and residents nearby. In this paper health risk assessments were performed for the VOCs in the ambient air of a typical biopharmaceutical R&D complex in China. Results showed halogenated and alkyl compounds were dominant components among 24 major VOCs from 9 selected sampling sites, inside or around the complex. The principal component analysis (PCA) indicated VOCs were generated predominantly from the biopharmaceutical research activities (factor 1 (F1), 71.6%) and traffic vehicles (factor 2 (F2), 15.4%), which were confirmed by contour maps of five selected VOCs (benzene, toluene, chlorobenzene, methylene chloride and n-hexane) simulated by Golden Software Surfer. The cumulative cancer risks for the staff on site and residents nearby were investigated and results showed the risk value were 1.01E−5 and 2.03E−5, respectively, higher than the threshold value of 1.0E−6. These results indicated that elevated VOCs from biopharmaceutical R&D complex are potential risks to the public health. Furthermore, the human health risk assessment revealed that 1,2-dichloroethane, methylene chloride, carbon tetrachloride and benzene were the dominant risk contributors for staff on site, while methyl chloride, carbon tetrachloride, 1,2-dichloroethane and tetrahydrofuran for residents nearby. As a conclusion, this work suggests that proper control strategy should be taken for VOCs releasing to minimize the public health risks, especially for the halogenated compounds.     

A simulation model for optimizing the concession period of public–private partnerships schemes

Public–private partnerships (PPP) are becoming an increasingly popular option of project delivery. Under the concession-based PPP arrangement, the private partner is responsible for funding the scheme, while their capital investment will be recovered through the operation revenue over the concession period. Therefore, calculating an appropriate investment return over the concession period becomes a very important aspect that influences success of the PPP project, particularly so as the concessionaire may be tempted to increase their toll/tariff should the revenue fall short of their expected. However, due to the difficulties in estimating the long-term uncertainties and wider-risk profiles at the tendering stage, the government would conduct the traditional net present value and payback period analyses to determine the concession period. In this paper, a simulation model which aims to assist the public partner to determine an optimal concession period is proposed. A hypothetical example is worked through to illustrate the concept of the simulation model. The results show that the risks and uncertainties, such as a change in inflation rate, traffic flow and operation cost, could influence the decision on the concession period. With the help of the simulation model, the impact of risk can be taken into account when establishing an ideal concession period.     

A fuzzy approach to construction project risk assessment

The increasing complexity and dynamism of construction projects have imposed substantial uncertainties and subjectivities in the risk analysis process. Most of the real-world risk analysis problems contain a mixture of quantitative and qualitative data; therefore quantitative risk assessment techniques are inadequate for prioritizing risks. This article presents a risk assessment methodology based on the Fuzzy Sets Theory, which is an effective tool to deal with subjective judgement, and on the Analytic Hierarchy Process (AHP), which is used to structure a large number of risks. The proposed methodology incorporates knowledge and experience acquired from many experts, since they carry out the risks identification and their structuring, and also the subjective judgements of the parameters which are considered to assess the overall risk factor: risk impact, risk probability and risk discrimination. All of these factors are expressed by qualitative scales which are defined by trapezoidal fuzzy numbers to capture the vagueness in the linguistic variables. The most notable differences with other fuzzy risk assessment methods are the use of an algorithm to handle the inconsistencies in the fuzzy preference relation when pair-wise comparison judgements are necessary, and the use of trapezoidal fuzzy numbers until the defuzzification step. An illustrative example on risk assessment of a rehabilitation project of a building is used to demonstrate the proposed methodology.     

基于物元可拓理论的高层建筑施工安全风险评估研究

在工程项目建设过程中,由于工程项目存在规模大、周期长、参与人员众多,导致工程建设存在诸多影响安全的不确定性因素,对于安全风险管理其核心就是对这些不确定性因素进行合理的预测和评估。结合高层建筑建设的特殊性及安全性的特点,构建高层建筑施工安全风险评价指标体系,将层次分析法和熵权法相结合,形成主观赋值权重与客观计算权重结合使用的评价指标组合权重。在此基础上建立模糊可拓评价模型,测算风险指标关联度,得到相应的风险综合评价等级。并结合江苏省某工程实例,对高层建筑安全风险进行综合评价,从而为多方案的比选提供科学依据。     

A FRAMEWORK FOR CLIMATE RISK MANAGEMENT APPLIED TO A UK WATER RESOURCE PROBLEM

Climate risk management is a new and evolving area and many decisions are likely to be affected by climate risks over the long-term. This paper presents a decision-making framework designed for managing climate alongside nonclimate risk factors. The framework describes a process that should help identify and manage these risks. It can be used to help decision-makers answer questions about whether adaptation is required, and, if so, which measures should be implemented. Adaptive management is recommended as a useful approach for dealing with climate and other uncertainties. This paper describes an application of the framework to a water resources case study. Feedback from training workshops based on four different case studies suggests the framework provides at minimum a useful (post-hoc) decision analysis tool. Potential users, who include planners, consultants and policy-makers have been largely positive about the prospective utility of the framework.     

Use of existing water, sediment, and tissue data to screen ecological risks to the endangered Rio Grande silvery minnow

A screening-level ecological risk assessment was applied to two extensive, but previously unanalyzed datasets from the middle Rio Grande (MRG) in New Mexico. The assessment evaluated how adverse water-quality effects from aquatic toxicants may have influenced the population decline of the endangered Rio Grande silvery minnow (Hybognathus amarus; silvery minnow). Standardized US Environmental Protection Agency (USEPA) screening-level ecological risk assessment procedures were applied to chemicals assessed in samples collected from the MRG between 1985 and 2003. Since more chemicals have established risk-screening criteria, relative to water-quality criteria, this approach produces more complete assessments. Chemical concentrations at some locations and times were potentially sufficient to affect fish health or produce localized mortalities. Many constituents displaying the highest risks have substantial natural sources within the watershed; native species likely would have adapted to natural instream concentrations such that actual risks might be markedly less than projected by a risk screening based on generic aquatic-life criteria. Also, highest risks found for individual and combinations of contaminants were very inconsistent both within and across the sites. As such, this risk assessment does not support the conclusion that toxicants were a primary factor causing the silvery minnow population to decline in the MRG between 1985 and 2003. The assessment indicates that sediment-borne, relative to water-borne, contaminants appeared to present the greatest risks to the silvery minnow and thus should have increased focus during future assessments of potential contaminant effects in the MRG. Contaminants of greatest concern are identified. This study presents approaches to cost-effectively assess and reduce uncertainties associated with potential water quality effects, and to help direct future assessments of water quality onto those contaminants likely to produce potentially significant effects. The techniques presented and criteria compiled are suitable for aiding similar assessments in other aquatic habitats.     

Assessment of human health risks posed by consumption of fish from the Lower Passaic River, New Jersey

The Lower Passaic River (LPR) in New Jersey has been impacted by variety of human activities over the course of the last two centuries. In this risk assessment, we assessed potential human health risks associated with consumption of fish from the LPR, the human exposure pathway of greatest concern when addressing contaminated sediments. Our risk assessment incorporates fish consumption information gathered during a year-long, intercept-style creel angler survey and representative fish tissue concentrations for 156 chemicals of potential concern (COPCs) obtained from USEPA's public database (OurPassaic website: http://www.ourpassaic.org/projectsites/premis_public/index.cfm?fuseaction=contaminants). Due to the large number of COPCs investigated, this risk assessment was divided into two phases: (1) identification of COPCs that contribute to the majority of overall excess cancer risk and hazard estimates using deterministic and probabilistic methods, and (2) probabilistic characterization of risk using distributions of chemical concentration and cooking loss for those compounds identified in Phase 1. Phase 1 relied on point estimates of COPC concentrations and demonstrated that PCDD/Fs and PCBs (dioxin-like and non-dioxin-like) are the greatest contributors to cancer risk, while non-dioxin-like PCBs are the primary contributors to non-cancer hazard estimates. Total excess cancer risks for adult and child and receptors estimated in Phase 1 were within USEPA's acceptable excess cancer risk range, with the exception of RME child (3.0 × 10^− 4 and 1.3 × 10^− 4 for deterministic and probabilistic approaches, respectively). Phase 2 focused on PCDD, PCDF, and PCBs and used distributions of chemical concentrations in fish. The results showed that all excess cancer risk estimates were within the acceptable risk range, although non-cancer hazard estimates for PCBs slightly exceeded a Hazard Index of 1. This HHRA of LPR fish ingestion represents the most comprehensive evaluation conducted to date, and demonstrates that measured concentrations of COPCs are not likely to pose a health risk to people who currently consume fish from the LPR.     

房地产项目投资风险评价研究

随着我国房地产整体产业的迅速发展,越来越多的资金投入房地产市场,与此同时各种不确定因素所造成的投资风险也越来越受到人们的重视,因此,在房地产投资行为中建立一个完整的房地产项目投资风险评价体系显得尤为重要。在房地产项目投资风险的相关理论基础上,通过 AHP 和物元理论的评价方法,建立相关风险评价体系,结合尧沙房地产项目的实际情况收集相关数据,对投资风险进行分析,分析结果表明该评价方法具有可行性。     

Novel methods for integrated risk assessment of cumulative stressors — Results from the NoMiracle project

This special issue covers the main results of the European Sixth Framework Integrated Research project NoMiracle (Novel Methods for Risk Assessment of Cumulative stressors in Europe). New tools to analyse, characterise and quantify the combined risks to health or the environment from multiple stressors are presented or reviewed. Examples of cumulative stressors are mixtures of chemicals alone or in combination with biological or physical environmental factors such as pathogens and climate extremes. Among the main findings, the scientific work points at the importance of time in dealing with toxicity, and in particular the toxicity of chemical mixtures, the natures of the uncertainties associated with risk assessment and the value of visualisation in identifying and quantifying the most relevant risks. A major conclusion of the project is that researchers and regulators should focus on the receptor rather than on the single stressor or combination of agents. There is also a need for more efforts on mechanistic understanding and for a mechanism-based framework for interpreting mixture/multiple stressor effects.The new tools are available on the internet (http://nomiracle.jrc.ec.europa.eu).     

Risk analysis and risk management

During the past several decades, the public has given increasing attention to environmental problems and increased their demands that these problems be solved. During this period, the difficulty and costs of solving the problems have become apparent. Environmental abatement programs must be effective in achieving the desired goals and efficient in achieving them at low cost. Risk analysis is necessary to quantify the benefits of proposed solutions in order to make them effective and efficient. The necessity for performing risk assessment stems from a presidential executive order, from a Supreme Court Decision, and from the public's demand for information about the extent of possible danger from a hazard, rather than knowing simply that it is a hazard. The science of risk analysis is an an early stage and so there are many uncertainties concerning interpretation of the estimates. This approach has sharpened the scientific questions and hastened improvements in scientific understanding. Risk analysis is most helpful when the analysis reflects the science, without intrusion of the risk assessor's values or attempts to force a risk management outcome by skewing the risk analysis.     

Public attitudes towards chemical hazards

Public concern over chemical hazards is increasing in a context where overall life expectancy has rapidly improved. However, people's expectations of safety continue to exceed the presently attained levels and a mistrust of technological expertise is pervasive. Paradoxically this may arise because the ordinary person has assimilated scientific notions of causality that partially replace religious or magical explanations for accidents and catastrophes.The public's perceptions of risk frequently diverge considerably (in either direction) from the probabilistic risk assessments made by engineers and scientists. Both assessments are usually wrong: reconciliation rather than confrontations should be sought. The public is not ‘irrational’, it has different reasons and values.A brief view is given of the methodology and main findings of research on perceived risk, both comparative approaches and those where perceptions of a single hazard are explored in detail. Illustrative studies of community attitudes to pesticides, chemical food additives and of people's beliefs about nuclear power are outlined.     

Options-based negotiation management of PPP–BOT infrastructure projects

The success of public–private partnership (PPP)–build–operate–transfer (BOT) projects largely depends on effectively mitigating the impact of a variety of risks and uncertainties, especially those influencing the revenue over time. Revenue instability is one of the main obstacles of PPP form of procurement. Government support, which is established as a clause in the concession agreement, should be carefully designed and well formulated. Options which arise from certain clauses in the contract are more valuable for risky projects. The purpose of this paper’s proposed model is to evaluate early fund generation options and also to calculate equitable bounds for a guaranteed revenue for the project sponsor under uncertainty and risk. The model is specially designed to alleviate the concern of revenue risk. To illustrate its applicability the methodology is then applied to a freeway PPP project and a power plant PPP project in Iran. The results show that the value of these options can indeed be significant and by applying the proposed systematic negotiation mechanism both public and private sectors can take advantage of its flexibility at the negotiation table. The proposed mechanisms can facilitate negotiations on the verge of a break down as well as accelerating ongoing negotiations that have become moribund.     

地铁区间施工周边环境安全风险评估方法研究

城市地铁施工通常规划在市区繁华地带,往往需下穿城市居住区和办公区,施工条件及周边环境复杂,不确定性因素多,容易对周边环境造成较大影响,是一项高风险建设工程,因此需要在地铁工程的施工过程中对周边环境进行风险评估,从而采取相应的风险控制措施。本文提出了一个基于相关向量分类机和贝叶斯网络的概率风险评估方法,针对地铁施工特点结合历史数据和专家经验,通过专家知识表达和数据分析描述风险影响因素的风险传播路径和影响程度,对地铁施工过程中引起的周边建筑物、管线等环境安全风险进行风险分析,从而作为安全措施的指导依据。该分析方法应用在武汉地铁二号线某一盾构隧道区间内,分析结果表明了该模型作为一种风险评估方法的可行性。     

Earthquake-related Natech risk assessment using a Bayesian belief network model

Natural hazard triggering technological disasters (Natech) events pose risks to industrial facilities and process plants. As these plants handle hazardous materials, they can endanger nearby residential areas and have financial consequences. Thus, proper Natech risk assessment is required for effective prevention, mitigation and emergency response planning at industrial plants and nearby residential areas. The parameters used to quantify Natech risk assessment are subject to uncertainties and their interactions are non-linear. In this study, a Bayesian belief network-based Natech risk assessment model is developed to assess the earthquake-related Natech risk considering different levels of uncertainties. The cause and effect relationships between different parameters are constructed based on published body of knowledge and expert knowledge. The capabilities of the proposed model are demonstrated for the earthquake-related Natech risk assessment of Kobe City, Higashinada Ward, Japan because of the Great Hanshin earthquake in 1995. The proposed model is also capable of performing both predictive analysis and diagnostic analysis.     

Toxicity equivalents and EPA's risk assessment of 2,3,7,8-TCDD

Toxicity equivalent factors (TEFs) have proved useful in estimating the toxicity of complex mixtures of chlorinated dibenzo-p-dioxins and dibenzofurans (CDDs/CDFs). An international consensus has formed around a specific set of TEF values as interim solution for addressing environmental contamination by CDDs/CDFs. This procedure capitalizes on the congener-specific analytical results that are more routinely available in recent years. The TEF approach should be updated as necessary and replaced by more definitive bioassay approaches as soon as practicable. In an independent activity, the USEPA considered a proposal to change (reduce) the cancer potency ascribed to 2,3,7,8-TCDD by a factor of 16. The recommendation was based upon an analysis of the literature and the Agency's earlier risk assessment. The proposal was reviewed by the Science Advisory Board, a group of outside scientific advisors. Subsequently, the Agency decided against making any changes in its assessment at this time. However, it is likely that a reassessment will be conducted shortly that will incorporate new data and a new approach to estimating of cancer risks posed by 2,3,7,8-TCDD.     

基于模糊故障树的盾构隧道施工成本风险评估

基于模糊故障树的相关理论,提出用模糊成本重要度的指标来评价盾构隧道施工中各风险对总成本的影响大小。使用信心指数法将专家的分数修正为三角模糊数;基于表现定理推导出三角模糊数相乘的精确求法,并求得各风险的模糊成本重要度。通过分析模糊成本重要度指标,得出了在盾构施工前应首先规避的风险。该方法为盾构隧道施工成本的风险评估提供了一种科学和可靠的手段。