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现有桥梁的可靠性分析 被引量:7
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作者 夏明进 霍达 滕海文 《北京工业大学学报》 CAS CSCD 北大核心 2004年第1期89-92,共4页
为了准确地把握现有城市公路桥梁的损伤程度,将桥梁评定单元划分为下部结构、支座、上部结构及桥面系等4个组合项目,每个项目包含若干个子项,从而形成子项、项目和单元3个层次,每个层次划分为4个等级.在各个层次上,直接对可靠性进行评级... 为了准确地把握现有城市公路桥梁的损伤程度,将桥梁评定单元划分为下部结构、支座、上部结构及桥面系等4个组合项目,每个项目包含若干个子项,从而形成子项、项目和单元3个层次,每个层次划分为4个等级.在各个层次上,直接对可靠性进行评级.组合项目的等级评定中引用了故障树的逻辑原理来表示构件可靠性和结构可靠性之间的关系,采用了传力树评级法.同时,把工程模糊论方法应用到结构可靠性分析中,按危险点所占比重划分桥梁组成部分的评定等级,由各组成部分的危险构件百分数可得到构件对各等级的隶属度,从而构成桥梁等级的评判矩阵.通过模糊矩阵的复合运算,对桥梁的危险性进行鉴定,为维护与加固的合理决策提供依据. 展开更多
关键词 桥梁 结构可靠性 故障树 工程模糊论 隶属度
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A Fuzzy-based Adaptive Genetic Algorithm and Its Case Study in Chemical Engineering 被引量:5
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作者 杨传鑫 颜学峰 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2011年第2期299-307,共9页
Considering that the performance of a genetic algorithm (GA) is affected by many factors and their rela-tionships are complex and hard to be described,a novel fuzzy-based adaptive genetic algorithm (FAGA) combined... Considering that the performance of a genetic algorithm (GA) is affected by many factors and their rela-tionships are complex and hard to be described,a novel fuzzy-based adaptive genetic algorithm (FAGA) combined a new artificial immune system with fuzzy system theory is proposed due to the fact fuzzy theory can describe high complex problems.In FAGA,immune theory is used to improve the performance of selection operation.And,crossover probability and mutation probability are adjusted dynamically by fuzzy inferences,which are developed according to the heuristic fuzzy relationship between algorithm performances and control parameters.The experi-ments show that FAGA can efficiently overcome shortcomings of GA,i.e.,premature and slow,and obtain better results than two typical fuzzy GAs.Finally,FAGA was used for the parameters estimation of reaction kinetics model and the satisfactory result was obtained. 展开更多
关键词 fuzzy logic controller genetic algorithm artificial immune system reaction kinetics model
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Comprehensively Context-Aware Approach to Guaranteeing Multimedia Conferencing Services
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作者 吴冀衍 田岳 +1 位作者 程渤 商彦磊 《China Communications》 SCIE CSCD 2013年第9期53-64,共12页
Service-Oriented Communication(SOC)is a key research issue to enable media communications using the Service-Oriented Architecture(SOA).Motivated by the necessity to guarantee the service quality of our webbased multim... Service-Oriented Communication(SOC)is a key research issue to enable media communications using the Service-Oriented Architecture(SOA).Motivated by the necessity to guarantee the service quality of our webbased multimedia conferencing system,we present a Comprehensively Context-Aware(CoCA)approach in this paper.One major problem in the existing end-to-end Quality of Service(QoS)management solutions is that they analyse and exploit the relationships between the QoS metrics and corresponding contexts in an isolated manner.In this paper,we propose a novel approach to leveraging such relationships in a comprehensive manner based on Bayesian networks and the fuzzy set theory.This approach includes three phases:1)information feedback and training,2)QoS-to-context mapping,and3)optimal context adaption.We implement the proposed CoCA in the real multimedia conferencing system and compare its performance with the existing bandwidth aware and playback buffer aware schemes.Experimental results show that the proposed CoCA outperforms the competing approaches in improving the average video Peak Signal-to-Noise Ratio(PSNR).It also exhibits good performance in preventing the playback buffer starvation. 展开更多
关键词 SOC multimedia conferencing CONTEXT-AWARE
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Fuzzy Comprehensive Assessment Method to Determine Tectonic Stress Patterns
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作者 张海 戚蓝 +1 位作者 郝彩哲 郭磊 《Transactions of Tianjin University》 EI CAS 2007年第6期462-468,共7页
The tectonic stress patterns were determined by a fuzzy comprehensive assessment method. Data of in-situ survey and fault information were utilized in the method. First, by making pressure and tension in the direction... The tectonic stress patterns were determined by a fuzzy comprehensive assessment method. Data of in-situ survey and fault information were utilized in the method. First, by making pressure and tension in the directions of along-river, cross-river, shear clockwise, and shear counterclockwise , 26 types of tectonic stress patterns were presented. And the stress vector of each pattern was obtained with FE software by taking unit displacement as boundary load. Then, by taking the 26 types of tectonic stress patterns as index set and 3 main stresses as factor set and choosing various operators, comparison of directions of computational stress vector and survey stress vector was made and the most possible tectonic stress pattern was obtained. Taking the 26 types of tectonic stress patterns as index set and strike angle as factor set, comparison of relationships between formation of fault and tectonic stress was made,and the tectonic stress patterns were assessed with known fault information. By summarizing the above assessment results, the most impossible tectonic stress pattern was obtained . Finally an engineering case was quoted to validate that the method is more feasible and reliable than traditional empirical method. 展开更多
关键词 in-situ stress tectonic stress patterns fuzzy comprehensive assessment FAULT
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