Risk tolerance measure for decision-making in fuzzy analysis: a health risk assessment perspective     

Elcin Kentel  Mustafa M. Aral 《Stochastic Environmental Research and Risk Assessment (SERRA)》2007,21(4):405-417

In risk assessment studies it is important to determine how uncertain and imprecise knowledge should be included into the simulation and assessment models. Thus, proper evaluation of uncertainties has become a major concern in environmental and health risk assessment studies. Previously, researchers have used probability theory, more commonly Monte Carlo analysis, to incorporate uncertainty analysis in health risk assessment studies. However, in conducting probabilistic health risk assessment, risk analyst often suffers from lack of data or the presence of imperfect or incomplete knowledge about the process modeled and also the process parameters. Fuzzy set theory is a tool that has been used in propagating imperfect and incomplete information in health risk assessment studies. Such analysis result in fuzzy risks which are associated with membership functions. Since possibilistic health risk assessment studies are relatively new, standard procedures for decision-making about the acceptability of the resulting fuzzy risk with respect to a crisp standard set by the regulatory agency are not fully established. In this paper, we are providing a review of several available approaches which may be used in decision-making. These approaches involve defuzzification techniques, the possibility and the necessity measures. In this study, we also propose a new measure, the risk tolerance measure, which can be used in decision making. The risk tolerance measure provides an effective metric for evaluating the acceptability of a fuzzy risk with respect to a crisp compliance criterion. Fuzzy risks with different membership functions are evaluated with respect to a crisp compliance criterion by using the possibility, the necessity, and the risk tolerance measures and the results are discussed comparatively.  相似文献   

Risk factors contributing to motor vehicle collisions in an environment of uncertainty     

Ellen K. Cromley 《Stochastic Environmental Research and Risk Assessment (SERRA)》2007,21(5):473-486

The concepts of medical geography provide a framework for investigating the importance of people–place interactions in risk analysis and assessing the roles of individual, behavioral, and environmental risk factors. Analyses of data on motor vehicle collisions in Connecticut in 1995 and 1996 are used to illustrate geographical variations in the characteristics of collisions. A method is presented for identifying high frequency collision sites for particular collision types. Proportions and odds ratios calculated as local statistics are used to highlight sites where the individual, behavioral, or environmental characteristics of collisions differ significantly from those in the state as a whole. These differences have implications for developing better statistical models for knowledge synthesis and policy development.  相似文献   

A systematic approach to synoptic tornado climatology of Hungary for the recent years (1996–2001) based on official damage reports     

Srkzi Szilrd 《Atmospheric Research》2007,83(2-4):263-271

Due to the significant amount of severe storm damage from the mid 1990s, a practical need has arisen for updating risk assessment. For reliable and systematic sampling of events, data acquisition has been arranged through the disaster management official body using a pyramidal national coverage. Post-analysis, including its meteorological part, proceeds in a GIS environment. This paper focuses specifically on damaging tornadoes, since those are the most violent and best-documented phenomena. Different statistics are calculated and explained, such as seasonal, diurnal and magnitude distributions. Spatial occurrence and features are mapped. A complete synoptic climatology is given by typifying the generating conditions and categorizing events into certain classes, while discussing the role of the Carpathian Basin. In the end a conceptual issue in connection with self-similarity is raised for further discussion.  相似文献   

Analysis of stability of earthen dams in kachchh region, Gujarat, India   总被引：2，自引：0，他引：2  

G.L. Sivakumar Babu  Amit Srivastava  V. Sahana   《Engineering Geology》2007,94(3-4):123-136

The Kachchh region of Gujarat, India bore the brunt of a disastrous earthquake of magnitude M_w = 7.6 that occurred on January 26, 2001. The major cause of failure of various structures including earthen dams was noted to be the presence of liquefiable alluvium in the foundation soil. Results of back-analysis of failures of Chang, Tappar, Kaswati and Rudramata earth dams using pseudo-static limit equilibrium approach presented in this paper confirm that the presence of liquefiable layer contributed to lesser factors of safety leading to a base type of failure that was also observed in the field. Following the earthquake, earth dams have been rehabilitated by the concerned authority and it is imperative that the reconstructed sections of earth dams be reanalyzed. It is also increasingly realized that risk assessment of dams in view of the large-scale investment made and probabilistic analysis is necessary. In this study, it is demonstrated that the probabilistic approach when used in conjunction with deterministic approach helps in providing a rational solution for quantification of safety of the dam and in the estimation of risk associated with the dam construction.  相似文献   

Defining probability of saturation with indicator kriging on hard and soft data     

Steve W. Lyon  Arthur J. Lembo Jr.  M. Todd Walter  Tammo S. Steenhuis 《Advances in water resources》2006

In humid, well-vegetated areas, such as in the northeastern US, runoff is most commonly generated from relatively small portions of the landscape becoming completely saturated, however, little is known about the spatial and temporal behavior of these saturated regions. Indicator kriging provides a way to use traditional water table data to quantify probability of saturation to evaluate predicted spatial distributions of runoff generation risk, especially for the new generation of water quality models incorporating saturation excess runoff theory. When spatial measurements of a variable are transformed to binary indicators (i.e., 1 if above a given threshold value and 0 if below) and the resulting indicator semivariogram is modeled, indicator kriging produces the probability of the measured variable to exceed the threshold value. Indicator kriging gives quantified probability of saturation or, consistent with saturation excess runoff theory, runoff generation risk with depth to water table as the variable and the threshold set near the soil surface. The probability of saturation for a 120 m × 180 m hillslope based upon 43 measurements of depth to water table is investigated with indicator semivariograms for six storm events. The indicator semivariograms show high spatial structure in saturated regions with large antecedent rainfall conditions. The temporal structure of the data is used to generate interpolated (soft) data to supplement measured (hard) data. This improved the spatial structure of the indicator semivariograms for lower antecedent rainfall conditions. Probability of saturation was evaluated through indicator kriging incorporating soft data showing, based on this preliminary study, highly connected regions of saturation as expected for the wet season (April through May) in the Catskill Mountain region of New York State. Supplementation of hard data with soft data incorporates physical hydrology of the hillslope to capture significant patterns not available when using hard data alone for indicator kriging. With the need for water quality models incorporating appropriate runoff generation risk estimates on the rise, this manner of data will lay the groundwork for future model evaluation and development.  相似文献   

Presentation of RISK-UE Project     

Pierre Mouroux  Benoît Le Brun 《Bulletin of Earthquake Engineering》2006,4(4):323-339

This paper is a presentation of an European project called RISK-UE, entitled: “An advanced approach to earthquake risk scenarios with applications to different European towns”. It gives the origin, the objectives and the organisation of the project, together with the content of the different workpackages comprising methodological aspects: different features of European town, seismic hazard, urban system exposure, vulnerability of current, historical and monumental buildings, vulnerability of lifelines and essential facilities, seismic risk scenario, with an application to the seven following cities: Barcelona, Bitola, Bucharest, Catania, Nice, Sofia and Thessaloniki. These studies were realized in close relation with the decisionmakers of these cities, in order that they implement Risk Management Plans and Plans of Action to effectively reduce seismic risk.  相似文献   

Modelling Seismic Hazard in Earthquake Loss Models with Spatially Distributed Exposure   总被引：1，自引：0，他引：1  

Helen Crowley  Julian J. Bommer 《Bulletin of Earthquake Engineering》2006,4(3):275-273

The prediction of possible future losses from earthquakes, which in many cases affect structures that are spatially distributed over a wide area, is of importance to national authorities, local governments, and the insurance and reinsurance industries. Generally, it is necessary to estimate the effects of many, or even all, potential earthquake scenarios that could impact upon these urban areas. In such cases, the purpose of the loss calculations is to estimate the annual frequency of exceedance (or the return period) of different levels of loss due to earthquakes: so-called loss exceedance curves. An attractive option for generating loss exceedance curves is to perform independent probabilistic seismic hazard assessment calculations at several locations simultaneously and to combine the losses at each site for each annual frequency of exceedance. An alternative method involves the use of multiple earthquake scenarios to generate ground motions at all sites of interest, defined through Monte–Carlo simulations based on the seismicity model. The latter procedure is conceptually sounder but considerably more time-consuming. Both procedures are applied to a case study loss model and the loss exceedance curves and average annual losses are compared to ascertain the influence of using a more theoretically robust, though computationally intensive, procedure to represent the seismic hazard in loss modelling.An erratum to this article can be found at  相似文献   

Risk-based environmental decision-making using fuzzy analytic hierarchy process (F-AHP)   总被引：1，自引：4，他引：1  

Solomon Tesfamariam  Rehan Sadiq 《Stochastic Environmental Research and Risk Assessment (SERRA)》2006,21(1):35-50

Environmental risk management is an integral part of risk analyses. The selection of different mitigating or preventive alternatives often involve competing and conflicting criteria, which requires sophisticated multi-criteria decision-making (MCDM) methods. Analytic hierarchy process (AHP) is one of the most commonly used MCDM methods, which integrates subjective and personal preferences in performing analyses. AHP works on a premise that decision-making of complex problems can be handled by structuring the complex problem into a simple and comprehensible hierarchical structure. However, AHP involves human subjectivity, which introduces vagueness type uncertainty and necessitates the use of decision-making under uncertainty. In this paper, vagueness type uncertainty is considered using fuzzy-based techniques. The traditional AHP is modified to fuzzy AHP using fuzzy arithmetic operations. The concept of risk attitude and associated confidence of a decision maker on the estimates of pairwise comparisons are also discussed. The methodology of the proposed technique is built on a hypothetical example and its efficacy is demonstrated through an application dealing with the selection of drilling fluid/mud for offshore oil and gas operations.  相似文献   

流域LUCC水文效应研究中的若干问题探讨   总被引：21，自引：2，他引：21  

万荣荣  杨桂山 《地理科学进展》2005,24(3):25-33

随着全球变化研究的深入,土地利用/覆被变化(LUCC)的水文效应研究日益成为热点问题。综合国内外研究进展,论文就流域土地利用/覆被变化水文效应研究中的几个问题进行了总结和探讨：子流域和水文响应单元是分布式水文模型对流域基本空间单元的理想划分;对国内外现有的土地利用分类系统进行了适当的调整和归并,建立了基于水文响应研究的土地利用分类系统,将土地利用分为9个Ⅰ级类和21个II级类;土地利用/覆被变化情景分析的常用方法有参照对比法、历史反演法、模型预测法、极端土地利用法、土地利用空间配置法等。  相似文献   

Longitudinal variability of soils and structural response of sewer networks     

Sidi Mohammed Elachachi  Denys Breysse  Laurent Houy 《Computers and Geotechnics》2004,31(8):625-641

A simple model which describes the soil–pipe interaction and accounts for the longitudinal soil variation has been developed. It is used for the analysis of the static response of a section of a buried sewer. A probabilistic analysis (Monte-Carlo method) enabling to quantify the influence of spatial variability of the geomechanical characteristics of the soil makes possible to study the parameters which can influence and drive the longitudinal response of a section of sewer. The system response is complex, soil–structure interaction depending on three different stiffnesses: soil stiffness, pipe components stiffness and joints stiffness. Various analyses have been performed to identify the parameters whose influence is the larger. A specific attention has been devoted to the fluctuation scale of the soil properties and to the stiffness of joints.  相似文献