风险分析的灰色—随机风险率方法研究

本文基于概率论和系统理论方法，定义了灰色概率、灰色概率分布、灰色概率密度、灰色期望及灰色方差等基本概念，针对系统的随机不确定性和灰色不确定性，建立了风险分析的灰色－随机风险率方法。在该方法中，作者将风险率的不确定性归因于系统的灰色不确定性，将系统性能函数变量的分布处理成灰色概率分布，并用灰色－随机风险率来量化系统失效的风险性。最后，将灰色－随机风险率转换成一般的随机风险率，进而用改进一阶二矩法进行计算。作为算例文中给出了该方法应用于嘉陵江苍溪段有机污染风险率的估算。     

基于集对分析的相似流域选择方法

集对分析（SPA）是处理不确定性问题的一种新理念，认为在一个系统中确定性与不确定性相互联系、影响、制约，并在一定条件下相互转化，用联系度来描述系统的各种不确定性，由此实现对系统的决策。为了改进水文计算中选择相似流域的经验性方法，首次提出了水文计算中相似流域选择的集对分析方法，用联系度来描述设计流域与参证流域的同异反程度。与其他方法相比，该方法具有概念明确、计算简便和实用的特点。     

一种基于满意度方法的建筑工程索赔决策模型

本文在对索赔问题进行全面系统分析基础上，提出一种索赔主体对索赔事件的不确定性分析模型和决策满意度模型，并进一步讨论了索赔主体优选索赔方案作为索赔报告提出的方法。     

水质综合评价的B—P人工神经网络模型

为探索人工神经网络用于水质综合评价的可能性，提出了基于Ｂ－Ｐ算法的人工神经网络综合评价模型，实例研究表明，Ｂ－Ｐ人工神经网络用于水质综合评价简便实用，具有客观性和通用性。     

京密引水工程闸门的防腐管理

水工钢闸门的防腐工作是水利工程管理的重要内容。目前钢结构防腐方法较多，其中被广泛应用的有金属喷镀、涂料保护、阴极保护和玻璃钢保护等。选择防腐方法时，既要力求获得较好的保护效果和较长的保护期效，又要考虑材料、设备的可能性和成本的高低，还要因地制宜。根据京密引水工程闸门小而多，又过于分散的特点，自１９８１年以来采用喷砂表面处理－涂装ＡＣ－１５氯化橡胶铝粉防锈漆和ＨＯ６－４环氧富锌漆的施工工艺，先后对１     

机械设计专家系统开发工具MDEST

介绍了一个机械设计专家系统开发工具ＭＤＥＳＴ，阐述了ＭＤＥＳＴ的规则－框架－过程知识表示，复合不精确推理方法及目标回溯策略。复合不精确推理方法可较好地解决机械设计中设计知识的不确定性，目标回溯策略是常规型机械设计实现再设计的一种有效的方法。     

应用洪泛区淹没有限元模拟模型预测漫滩沉积型式

漫滩淹没及漫滩流的数学模拟面临着许多困难，这种研究仍处于起步阶段。到目前为止，研究只限于较小的河段。那种基于更长河段的大型模型对工程和洪泛区管理来说可能具有更大价值，但需要对从小型转换到大型模拟中遇到的问题进行评估，一个大型有限元模型，即RMA－2被应用到英国丹佛东南Culm河下游的洪泛区模拟之中，运用洪水淹没期间漫滩游积中的放射性铯沉积数据，评估了运用上述这类模型分析淤积率和型式的可能性，发现铯－137存量及表面浓度与由RMA－2模型估算的洪水型式之间存在着密切相关，除了在退水时发生蓄水的地方外，铯－137沉积与水深之间存在着反比关系，不过，研制的离散模型目前尚不能用来对水流进行大规模区域化，这是因为存在水流障碍和微型地形特征，如横穿洪泛区的沟渠和洪泛区小地形等，本研究评估了运用RMA－2模型预测漫滩淤积型式的可能性，它代表了研制综合型水力和泥沙动态模型的开始阶段。     

水工结构振周期经验公式的模糊随机统计回归方法

计算结构自振周期的经验公式一般是用统计回归方法得出的，但是以往的统计回归方法只考虑自振周期的随机性，而未涉及另外一类不确定性－－模糊性。提出一种可以同时考虑水工结构自振周期的随机性和模糊性的统计回归方法－－水工结构自振经验公式的模糊随机统计回归方法。     

已建坝的风险分析--可信度的优点与局限

风险分析是在不确定的情况下响应决策的方法。不确定性在大坝的生命周期中是普遍存在的 ,可能比其它任何一种土木建筑更普遍 :地质、水资源管理、地震和洪水、施工计划、成本与融资、大坝安全管理与下游风险。将工程判断转化为数据时的偶然性差错 ,由在替代方案中允许进行合理选择的可能性所补偿 ,并且由量化成本与风险之间的比较方案的透明度来衡量。然而 ,误用和误差也有其缺陷。本文从正反两方面阐述了一些观点的精华。     

供水工程设计中的决策分析风险

介绍决策分析法在小规模供水和地下含水层污染问题中的应用。在不同风险条件下，提出了一系列确保连续供水的优选方案。在风险分析中，假定渗透系数为不确定因素。为了评估所有设计方案在系统运作中不确定性的本质，使用了地下水径流和污染物运动随机模拟模型。通过综合考虑实际费用和概率费用，确定了优选方案，并运用风险－费用－效益目标函数进行了比选。     

Modelling Impacts of Climate Change on a River Basin: Analysis of Uncertainty Using REA & Possibilistic Approach

In the context of climate change, the uncertainty associated with Global Climate Models (GCM) and scenarios needs to be assessed for effective management practices and decision-making. The present study focuses on modelling the GCM and scenario uncertainty using Reliability Ensemble Averaging (REA) and possibility theory in projecting streamflows over Wainganga river basin. A macro scale, semi-distributed, grid-based hydrological model is used to project the streamflows from 2020 to 2094. The observed meteorological data are collected from the India Meteorological Department (IMD) and the streamflow data is obtained from Central Water Commission (CWC) Hyderabad. In REA, meteorological data are weighted based on the performance and convergence criteria (GCM uncertainty). Whereas in possibility theory, based on the projection of different GCMs and scenarios during recent past (2006–2015) possibility values are assigned. Based on the possibility values most probable experiment and weighted mean possible CDF for the future periods are obtained. The result shows that there is no significant difference in the outcomes is observed between REA and possibility theory. The uncertainty associated with GCM is more significant than the scenario uncertainty. An increasing trend in the low and medium flows is predicted in annual and monsoon period. However, flows during the non-monsoon season are projected to increase significantly. Moreover, it is observed that streamflow generation not only depends on the change in precipitation but also depends on the previous state of physical characteristics of the region.     

Estimation of uncertainty in long term combined sewer sediment behaviour predictions, a UK case study.

There are regulatory driven requirements for UK water companies to reduce the number of properties at risk of sewer flooding. One of the potential causes of sewer flooding is the presence of persistent sediment deposits in sewers. This is a common problem in many combined sewers. Although the regulation is risk based, there is a gap in current knowledge on how risk assessment is affected by the uncertainty in sewer solids behaviour prediction. This paper describes a UK case study exploring the possibility of estimating uncertainty in sewer sediment deposit level predictions, using Monte Carlo simulations combined with a response database.     

Complex efficiency indicator for separators in dust-preparation plants

A relationship for determination of the complex efficiency hcom of a separator, which graphically reflects the effectiveness of its operation from the standpoint of both output of prepared dust with an assigned amount retained on a sieve, and also with consideration of the extent to which fine fractions of final dust are excluded from the return, is presented on the basis of analysis of existing methods of determining classifier efficiency, experience with their use in power engineering, and the function of dust separators of coal-pulverizing mills in the production process of boiler plants at TPP. A procedure is proposed for determination of the value of hcom when an assigned amount of final dust is retained on a sieve during operation. The possibility of determining complex separator efficiency for mills with a built-in separator is analyzed. __________ Translated from élektricheskie Stantsii, No. 6, July 2007, pp. 6–10.     

Are Pulp and Paper Mills Sources of Toxaphene to Lake Superior and Northern Lake Michigan?

Toxaphene was a broad-spectrum pesticide consisting of a mixture of highly chlorinated bornanes and bornenes. After its ban in 1982, toxaphene concentrations have shown a general decline in the environment as a whole and in most of the Great Lakes specifically. Recent work, however, shows that toxaphene concentrations are not decreasing in fishes from Lake Superior and northern Lake Michigan. Non-atmospheric, relatively localized sources are a possible explanation for these observations. For example, toxaphene could be inadvertently produced and released by pulp and paper mills, which could be synthesizing toxaphene-like compounds as a byproduct of bleached paper production. Reported here is a study of surficial river sediment collected upstream and downstream from seven pulp and paper mills, from five areas of previous toxaphene use, and from two presumed pristine locations. Concentrations of toxaphene found downstream are similar to those found upstream from each of the pulp and paper mills. Concentrations in sediment from rivers near previous toxaphene use locations were higher than concentrations in the background samples. These data suggest that pulp and paper mills are not now sources of toxaphene but that toxaphene used as a pesticide in the Great Lakes basin (although these uses were very small compared to its use in the southern US) could be a potential source.     

Risk analysis of slope instability of levees under river sand mining conditions

Levees are affected by over-exploitation of river sand and river adjustments after the formation of sand pits. The slope stability is seriously threatened, drawing wide concern among experts and scholars in the area of water conservancy. This study analyzed the uncertainties of slope stability of levees under river sand mining conditions, including uncertainty caused by interest- driven over-exploitation by sand mining contractors, and uncertainty of the distance from the slope or sand pit to the bottom of the levee under the action of cross-flow force after the sand pit forms. Based on the results of uncertainty analysis, the distribution and related parameters of these uncertainties were estimated according to the Yangtze River sand mining practice. A risk model of the slope instability of a levee under river sand mining conditions was built, and the possibility of slope instability under different slope gradients in a certain reach of the Yangtze River was calculated with the Monte Carlo method and probability combination method. The results indicated that the probability of instability risk rose from 2.38% to 4.74% as the pits came into being.     

Predicting Variability in a Lake Ontario Phosphorus Model

The prediction of a model always has a degree of uncertainty. Because the level of uncertainty is inversely related to the value of information contained in the prediction, there is a need to quantify the uncertainty. One approach to estimate prediction uncertainty is first-order error analysis. In this method, the error in a characteristic (variable or parameter) is defined by its first nonzero moment (the variance). Errors are propagated through the model using first-order terms in the Taylor series, and the variances are then combined to yield the total prediction uncertainty. An alternative approach to model prediction error analysis is Monte Carlo simulation. In this technique, probability density functions are assigned to each characteristic (variable or parameter), reflecting the uncertainty in that characteristic. Then, values are randomly selected from the distribution for each term and inserted into the model, to calculate a prediction. Repeating this process a number of times produces a distribution of predicted values, which reflects the combined uncertainties. These two approaches (first-order error analysis and Monte Carlo simulation) are applied to Lake Ontario data using a steady state mass balance phosphorus model. Comparisons are made which suggest guidelines for the use of each.     

长江上游主要河流径流丰枯空间变化特性初步研究

集对分析是处理不确定性问题的一种新理念,认为在一个系统中确定性与不确定性相互联系、影响、制约并在一定条件下相互转化,用联系度来描述系统的各种不确定性,由此实现对系统的评价和决策。河川径流存在大量的不确定性,应用有序聚类方法建立径流丰枯状态的分级标准,然后运用集对的联系度来描述各水系间丰枯状态的同异反程度。以长江上游主要河流52 a的径流资料为基础进行了具体应用,结果表明:长江上游主要河流径流总体具有丰枯同步的特点。     

Complexity in hydroecological modelling: A comparison of stepwise selection and information theory

Understanding of the hydroecological relationship is vital to maintaining the health of the river and thus its ecosystem. Stepwise selection is widely used to develop numerical models which represent these processes. Increasingly, however, there are questions over the suitability of the approach, and coupled with the increasing complexity of hydroecological modelling, there is a real need to consider alternative approaches. In this study, stepwise selection and information theory are employed to develop models which represent two realizations of the system which recognizes increasing complexity. The two approaches are assessed in terms of model structure, modelling error, and model (statistical) uncertainty. The results appear initially inconclusive, with the information theory approach leading to a reduction in modelling error but greater uncertainty. A Monte Carlo approach, used to explore this uncertainty, revealed modelling errors to be only slightly more distributed for the information theory approach. Consideration of the philosophical underpinnings of the two approaches provides greater clarity. Statistical uncertainty, as measured by information theory, will always be greater due to its consideration of two sources, parameter and model selection. Consequently, by encompassing greater information, the measure of statistical uncertainty is more realistic, making an information theory approach more reflective of the complexity in real‐world applications.     

A new methodology for the CFD uncertainty analysis

With respect to the measurement uncertainty, this paper discusses the definition, the sources, the classification and the expressions of the CFD uncertainty. Based on the orthogonal design and the statistics inference theory, a new verification and validation method and the related procedures in the CFD simulation are developed. With the method, two examples of the CFD verification and validation are studied for the drag coefficient and the nominal wake fraction, and the calculation factors and their interactions which would significantly affect the simulation results are obtained. Moreover, the sizes of all uncertainty components resulting from the controlled and un-controlled calculation factors are determined, and the optimal combination of the calculation factors is obtained by an effect estimation in the orthogonal experiment design. It is shown that the new method can be used for the verification in the CFD uncertainty analysis, and can reasonably and definitely judge the credibility of the simulative result. As for CFD simulation of the drag coefficient and the nominal wake fraction, the results predicted can be validated. Although there is still some difference between the simulation results and the experiment results, its approximate level and credibility can be accepted.     

Uncertainty and precaution in European environmental risk assessment of chemicals.

It is recognised that there is a need for a proper treatment and transparency of uncertainty in risk assessment and management, especially in view of the upcoming proposed new chemical policy REACH, which delegates the responsibility for conducting risk assessments to industry. The current EU risk assessment for new and existing substances is largely deterministic and prudential measures are implicitly embedded in calculation schemes and rules. In this paper, a more probabilistic approach to risk assessment is advocated. The advantage is twofold: 1) inherent variability and other uncertainty pertaining to exposure and effects are transparently taken into account, while at the same time 2) issues of caution are explicitly transferred to the risk management phase. The result of a probabilistic risk assessment as suggested is improved transparency with quantitative and qualitative uncertainty estimates. Such uncertainty information can be used to discuss precautionary measures in the context of risk management.