模糊权马尔可夫模型在桥梁状况预测中的应用

以马尔可夫链方法为基础,针对桥梁技术状况值为相依随机变量的特点,采取以规范化的各阶自相关系数为权重,用加权马尔可夫链来预测未来技术状况,在此基础上,根据模糊集理论中的级别特征值,计算出具体的技术状况值,最后,以一实桥前20年的检测资料为实例,对该方法进行了具体的应用,并与灰色模型及灰色马尔可夫链模型等的计算结果进行对比分析,证实了该模型的预测精度。     

A fuzzy set approach for bridge traffic safety evaluation1

On the basis of an extensive literature survey a set of factors that affect traffic safety on bridges was identified. These were grouped into three categories: bridge related, approach roadway related and environmentally related. A detailed accident analysis of a selected number of bridges in the state highway system of Indiana was conducted to verify these factors and to obtain insights into bridge accidents.

A bridge traffic safety evaluation model was developed based on fuzzy set mathematics and the concept of linguistic variables. All subjective evaluations in the model are represented as fuzzy sets which are then considered as fuzzy numbers for the purpose of calculations. The weighted averages for the fuzzy weights and fuzzy ratings are calculated for each group of contributing factors. These weighted averages are then logically combined to obtain the Bridge Safety Index.

The model takes into consideration the cumulative effect of the three groups of contributing factors related to bridge, approach roadway and environmental conditions. The resulting index, which is in the form of a fuzzy set, is transformed into the closest fuzzy number to represent the degree of bridge safety.     

神经网络在桥梁结构等级状态评估中的应用

探讨了模糊数学中的隶属函数在桥梁技术等级状态评估中的应用。在研究现有桥梁状态评估方法的基础上,把人工神经网络和模糊数学理论结合起来应用于大跨度预应力斜拉桥的结构等级状态评估,建立了基于3层神经元的模糊神经网络模型,并建立结构损伤度函数及结构等级隶属度模型,通过样本学习训练,获取评估专家的知识及直觉思维,最终确定桥梁所对应的技术状态等级。以检测的150组线形检测数据作为学习样本,另外8组作为验证样本进行了线形状态评估预测。计算结果表明,网络预测值与期望值吻合良好。     

A fuzzy mathematical approach for bridge condition evaluation

There are presently no established guidelines available for a bridge inspector to follow when assessing the significance of multiple deterioration factors on the bridge condition rating. As such, the evaluation of an existing bridge is based on a highly subjective and non-uniform procedure, and usually suffers from imprecision and personal bias. Hence, any attempt to find the optimal solution for bridge management based on such rating procedure can be misleading. However, with the development of a fuzzy mathematical approach, human subjectivity and imprecision can be included systematically in the decision making process.     

Bridge Condition Rating Using an Eigenvector of Priority Settings

Abstract: To circumvent possible inconsistencies in inspection and rating of highway bridges, two models based on fuzzy logic have been proposed in the literature. These models combine the condition rating of the various elements of the main bridge components to evaluate the overall condition of these components. The first method uses fuzzy weighted average, and the second uses the fuzzy computational technique known as resolution identity of fuzzy sets. A third model proposed by the authors and implemented in a knowledge-based expert system environment is presented in detail. The fuzzy inference model is based on a priority setting obtained through the solution of an eigenvector problem involving a pairwise comparison matrix of importance. This method and the associated solution technique were developed originally for general use in multiattribute decision making but were never used in a bridge engineering application. The proposed model is superior to other models for bridge rating previously developed because it provides priority settings of the individual elements of a bridge component in addition to the final rating of that component. The computer program was tested using actual bridge inspection data.     

基于可变模糊集的研究型大学教学质量评价研究

针对研究型大学建设工程类课堂教学特点,从＂学评教＂角度构建了研究型大学课堂教学质量评价指标体系,应用语气算子与定量标度相对隶属度关系确定各指标权重,利用可变模糊集理论与评价模型对课堂教学质量进行定量评价。通过评价实例说明可变模糊集评价模型的原理与计算步骤,印证应用该模型的可行性和有效性。     

在役桥梁耐久性状态评估

长期以来桥梁状态评估都忽视了耐久性评估,桥梁结构是一个复杂的系统,影响其耐久性状态的因素复杂而繁多。层次分析法(AHP法)将复杂的系统层次化、简单化,并通过比较各影响因素的重要性确定评估指标的初始权重。根据评估指标的初始权重和检测数据,利用变权原理确定评价指标的变权重。模糊综合评估法较好地解决了桥梁结构的模糊性和算法的确定性之间的矛盾。基于层次分析法,结合斜拉桥自身结构特点根据相关规范建立了斜拉桥耐久性状态评估递阶层次模型。在理论分析的基础上给出了桥梁耐久性状态模糊综合评估法的流程图。     

Fourth international conference on applications of statistics and probability in soil and structural engineering (ICASP-4)

An approach is presented to estimate pollutant loads and concentrations in runoff using fuzzy sets. In introducing uncertainty in water quality simulation models, fuzzy sets seem as appropriate as other techniques to represent the variability of the model's parameters and to predict pollutant loads with a measure of their uncertainty. In addition, the numerical implementation is efficient compared to other schemes. A modified version of the Storm Water Management Model that includes fuzzy sets is presented with the associated calibration method. Application of the procedure is illustrated for two watersheds and several pollutants.     

基于数学模糊逻辑的土地利用动态可视化

城市土地利用GIS专题数据都是某个时间点的静止数据,不能动态表达空间变化,本文提出基于数学模糊逻辑空间内插方法实现土地利用动态可视化表达,并以2个不同时期土地图斑空间内插为例说明该方法的有效性.     

AN APPLICATION OF FUZZY SETS TO TRANSPORT PROJECT APPRAISAL

This paper reviews some of the theory continuous fuzzy sets or subsets and illustrates, by way of example, an application to project appraisal in land use and transportation planning. In particular, a detailed illustration of the application of continuous fuzzy sets (fuzzy numbers) to the assessment of four alternative routes for a part of a proposed Eastern Corridor between the Cities of Brisbane and the Gold Coast, Queensland, Australia, is presented.     

桥梁结构状态评估的现况、方法及问题综述

本文简要介绍了国内外桥梁结构状态评估的现况,在此基础上,阐述了可靠度理论、层次分析法、模糊理论、神经网络以及基于损伤力学和疲劳断裂等桥梁结构常用的状态评估理论及方法。最后,较详细阐述了桥梁评估的过程,说明了目前桥梁评估中存在的问题,以及桥梁评估问题的本质探究。     

建筑安全管理本质安全化系统模型研究

本质安全理论是当代安全科学技术的重要成果,采用本质安全化的思路进行建筑安全管理是一种全新的理念,体现了安全管理由被动型向主动型转变的趋势。为此构建了建筑安全管理本质安全化系统模型,建立了基于Vague集的建筑安全管理系统本质安全化综合评价方法,在了解系统各个因素安全状况的同时,可以掌握系统整体的安全状况,以指导建筑安全管理的实践。     

模糊综合评价法在桥梁工程评判中的应用

本文阐述了用模糊综合评价法对桥梁工程的技术状况和运行状态评判的基本原理和方法步骤,并通过一个实际例子详细介绍了模糊综合评价方法在桥梁工程评判中的应用,进一步说明综合利用多种评价方法的优点应用于桥梁工程评判的重要性,对桥梁工程的评判颇有现实意义。     

基于模糊可变集合理论的地下水质量综合评判

对模糊可变集合理论作了简单介绍,在此基础上,以河北某地的地下水水质监测资料为例,说明了模糊可变集合模型在地下水质量综合评判中的应用过程,并根据计算出的级别特征值,确定了地下水的质量等级。     

Assessment of the safety of earth dams

The assessment of safety of earth dams based on the results of preliminary inspections is analyzed by fuzzy calculus. Fuzzy sets are used to represent the engineer's judgement on the seriousness (gravity) of observed defects and their relation to dam dafety. Two analytical models are proposed and applied to three earth dams exhibiting different types of defects. The results of the calculations are compared with the engineer's recommendations.     

Solid waste management under uncertainty: a generalized fuzzy linear programming approach

In this study, a generalized fuzzy linear programming (GFLP) method is developed to identify optimal waste-flow-allocation schemes under uncertainty. A stepwise interactive algorithm (SIA) is advanced to solve the GFLP model and generate solutions expressed as fuzzy sets. This solution method can handle fuzzy sets with known membership functions, regardless of the shapes of these functions. Moreover, solutions expressed as fuzzy sets can also be obtained through SIA. The developed method is applied to a case study of waste allocation planning problem under uncertainty. The results indicate that reasonable solutions can be obtained for planning waste allocation practices. Compared with interval solutions derived from interval linear programming method, the fuzzy solutions obtained through GFLP can provide more information. Therefore, the decision-makers can make tradeoffs between system stability and plausibility and thus identify desired policies for solid waste planning under uncertainty.     

桥梁基桩桩端溶洞顶板稳定性的模糊分析研究

基于模糊集理论,结合湖南省某跨渠桥桩基工程地质勘察资料,建立了桥梁基桩桩端溶洞顶板稳定性的模糊二级综合评判模型与模糊极限平衡分析模型,并分别解决了相应的模糊分析参数构造与评价方法问题,最后分别应用于某一实际工程,分析结论基本相同且与实际情况符合良好,为岩溶区桥梁基桩桩端溶洞顶板稳定性评价提供了新的思路和方法。     

基于云重心理论的桥梁技术状态评定方法

鉴于现行桥梁技术状态评定方法未体现评定过程模糊性和随机性的不足,本文将云重心评价理论及劣化模型引入到桥梁技术状态评定当中,在桥梁技术状态的云划分方法的基础上,分别建立各层级结构与构件的云模型,将桥梁技术状态划分为5个云图,建立基于云重心理论的桥梁技术状态评定方法,获得了桥梁技术状态劣化模型,对南宁大桥采用云重心方法及现行规范方法进行详细的技术状态评价,研究表明,本文提出的方法与规范方法评估结果等级相同,但本文提出的模型同时考虑了桥梁技术状态评定过程中的随机性和模糊性,在桥梁技术状态评定中具有很高的可信度和广泛的适用性。     

基于云重心理论的桥梁技术状态评定方法

鉴于现行桥梁技术状态评定方法未体现评定过程模糊性和随机性的不足,本文将云重心评价理论及劣化模型引入到桥梁技术状态评定当中,在桥梁技术状态的云划分方法的基础上,分别建立各层级结构与构件的云模型,将桥梁技术状态划分为5个云图,建立基于云重心理论的桥梁技术状态评定方法,获得了桥梁技术状态劣化模型,对南宁大桥采用云重心方法及现行规范方法进行详细的技术状态评价,研究表明,本文提出的方法与规范方法评估结果等级相同,但本文提出的模型同时考虑了桥梁技术状态评定过程中的随机性和模糊性,在桥梁技术状态评定中具有很高的可信度和广泛的适用性。