Bivariate Constant-Stress Accelerated Degradation Model and Inference Based on the Inverse Gaussian Process

Modern highly reliable products may have two or more quality characteristics (QCs) because of their complex structures and abundant functions. Relations between the QCs should be considered when assessing the reliability of these products. This paper conducts a Bayesian analysis for a bivariate constant-stress accelerated degradation model based on the inverse Gaussian (IG) process. We assume that the product considered has two QCs and each of the QCs is governed by an IG process. The relationship between the QCs is described by a Frank copula function. We also assume that the stress on the products affects not only the parameters of the IG processes, but also the parameter of the Frank copula function. The Bayesian MCMC method is developed to calculate the maximum likelihood estimators (MLE) of the model parameters. The reliability function and the mean-time-to-failure (MTTF) are estimated through the calculation of the posterior samples. Finally, a simulation example is presented to illustrate the proposed bivariate constant-stress accelerated degradation model.     

Human reliability analysis method on armored vehicle system considering error correction

Human reliability analysis(HRA) is an expansion of man-machine engineering. It is also a new multidisciplinary based on behavioral science, cognitive science, information processing, system analysis and probability statistics in order to analyze, predict, reduce and prevent human errors. Firstly, the quantitative analysis model of HRA is proposed based on Markov process theory by using human error probability(HEP) and error correction cycle(ECC) as parameters. And human reliability evaluation criterion is built. Then, the HRA process considering error correction is proposed based on cognitive reliability and error analysis method(CREAM). Finally, according to the characteristics of armored vehicle system, common performance condition(CPC) in CREAM is improved.A reliability impact index is characterized by the overall contexts of tasks. Human reliability evaluation criterion of armored vehicle system is formulated. And the result of HRA is obtained based on the method presented in this paper. In addition, the relative weights are estimated by combining scale of 10/10—18/2 and analytical hierarchy process(AHP), and the triangular fuzzy number considering confidence factor and optimism index is adopted in order to reduce the subjectivity. The analysis results show that the method presented in this paper is reasonable and feasible. Meantime, the method can provide guidance for human reliability analysis of other weapon systems.     

Reliability Prediction Method Based on State Space Model for Rolling Element Bearing

Reliability analysis based on equipment’s performance degradation characteristics is one of the significant research areas in reliability research. Nowadays, many researches are carried on multi-sample analysis. But it is limited for a single equipment reliability prediction. Therefore, the method of reliability prediction based on state space model(SSM) is proposed in this research. Feature energy of the monitored signals is extracted with the wavelet packet analysis and the associated frequency band energy with online monitored data. Then,degradation feature is improved by moving average filtering processing taken as input pair model parameter of SSM to be estimated. In the end, state space predicting model of degradation index is established. The probability density distribution of the degradation index is predicted, and the degree of reliability is calculated. A real testing example of bearing is used to demonstrate the rationality and effectiveness of this method. It is a useful method for single sample reliability prediction.     

奥运应急交通疏散预案评价指标体系研究

在研究应急交通疏散特点的基础上,结合2008年北京奥运的预计情况,提出了奥运应急交通疏散预案评价指标体系.从大量评价指标中筛选出疏散时间、疏散路网畅通可靠性、平均疏散距离、救援到位率、避难所服务水平及疏散代价等6项评价指标,选用TOPSIS法对预案进行综合评价,得出了较为合理的评价结果.     

Research on network maintenance strategy selection based on analytic hierarchy process and technique for order preference by similarity to ideal solution algorithm

Network maintenance strategy selection is a multi-objective decision making topic. It mostly depends on the uncertainty and fuzziness of decision makers and conditions. In this paper, based on analytic hierarchy process (AHP) and technique for order preference by similarity to ideal solution (TOPSIS), TOPSIS partial order method is proposed to choose the optimal maintenance strategy. This method uses AHP to determine the weights of evaluation indexes. The optimal maintenance strategy choice is given as an example to demonstrate the effectiveness of the method.     

基于熵值法和TOPSIS方法的地铁列车交路评估研究

由于地铁列车交路对地铁运营效率有着显著影响,针对地铁列车交路评估,提出一种基于熵值法和逼近理想解排序（TOPSIS）法的地铁列车交路方案评估方法.为更好地反映专家评估中的模糊性,评估指标信息值用语言值给出,采用通用二元语义对语言值进行处理以避免语言信息在运算中过程中失真和扭曲,并提出基于二元语义的成本型指标与效益性指标的转换公式,基于熵值法确定评估指标为二元语义信息的指标权重求解方法.最后,提出基于语言值的TOPSIS的评估方法对地铁列车交路方案排进行排序,并给出地铁列车交路评估实例、结果验证方法的有效性和可行性.     

变邻域搜索求解公共交通乘务调度问题

公共交通乘务调度问题是一个将车辆工作切分为一组合法班次的过程,它是NP难问题,许多求解方法的效率都与班次评价密不可分,本文通过裁剪TOPSIS方法(Technique for Order Preference by Similarity to an Ideal Solution)设计了TOPSIS班次评价方法.此外,通过裁剪变邻域搜索算法使之适合求解乘务调度问题,提出了基于变邻域搜索的乘务调度方法(Crew Scheduling Approach Based on Variable Neighbourhood Search,VNS),其中,并入了TOPSIS班次评价方法在调度过程中进行班次评价,设计了两种带概率的复合邻域结构以增加搜索的多样性,帮助跳出局部最优,在VNS中利用模拟退火算法进行局部搜索.利用中国公共交通中的11组实例进行了测试,测试结果表明,VNS优于两种新近提出的乘务调度方法,且其结果关于班次数接近于下界.     

基于多层复杂网络的中欧班列运输网络关键节点识别研究

若运输网络中的重要节点发生故障,中欧班列的运输效率和货物流动会受到严重制约。 本文提出一种基于改进TOPSIS(Technique for Order Preference by Similarity to an Ideal Solution) 法及灰色关联分析的多层网络节点重要性评价方法。首先,以中欧班列运输网络结构特征为基础,构建中欧班列多层网络;其次,选取度中心性、介数中心性及接近中心性等多个评价指标,运用改进TOPSIS法计算节点单层网络重要度评价值,采取灰色关联分析融合得到节点综合重要度评价值;最后,利用多层网络SIR(Susceptible Infected Recovered Model)模型验证方法的有效性。 结果表明：本文识别出的关键节点包含中欧班列主要线路的起讫城市、境内外重要口岸和中欧班列集结中心,结果与实际情况较为契合;采用排序前10%重要节点作为初始感染节点,SIR网络感染率在 20 次迭代后达到 97.8%,本文提出方法的网络节点感染率及传播速率均高于 BC (Betweenness Centrality)算法、DC(Degree Centrality)算法和PageRank算法等传统单一网络排序方法,即识别的关键节点对全局网络的影响更为普遍和高效。此外,根据排序结果从国家层面提出相应的政策建议,有助于提高中欧班列运输网络的鲁棒性。     

基于可靠性最短路的实时定制公交线路优化研究

为实时优化定制公交线路，提出一种基于可靠性最短路的线路优化方法，在复杂的交通环境中，可以高效的将乘客送达目的地. 对可靠性最短路进行问题描述，建立可靠性时空网络；给出求解可靠性最短路的算法步骤，构建乘客和定制公交运营商总成本最小的目标函数，采用禁忌搜索算法对问题进行求解；最后，以某市定制公交路网进行实例分析. 结果表明：与最短路线路方案比较，所提方法更接近于实际运营；在高峰时段，交通拥堵的情况下，所提方法可以提高车辆的可靠性，提升定制公交线路的服务水平.     

基于可靠性最短路的实时定制公交线路优化研究

为实时优化定制公交线路，提出一种基于可靠性最短路的线路优化方法，在复杂的交通环境中，可以高效的将乘客送达目的地. 对可靠性最短路进行问题描述，建立可靠性时空网络；给出求解可靠性最短路的算法步骤，构建乘客和定制公交运营商总成本最小的目标函数，采用禁忌搜索算法对问题进行求解；最后，以某市定制公交路网进行实例分析. 结果表明：与最短路线路方案比较，所提方法更接近于实际运营；在高峰时段，交通拥堵的情况下，所提方法可以提高车辆的可靠性，提升定制公交线路的服务水平.     

基于动态分流元胞传输模型的城市道路网络韧性评估

为全面评估重大扰动事件下城市道路网络抵御扰动并从扰动中快速恢复的能力，提出以改进元胞传输模型模拟路网流量分布状态，以韧性为测度指标的路网性能评估模型。针对传统元胞传输模型交叉口分流比例恒定的不足，明确考虑扰动事件影响期内因出行者调整路径可能导致的路径流量波动，构建出行决策行为与元胞流量传输的强耦合机制，提出一种新的动态分流元胞传输模型；基于动态分流元胞传输模型获得的路网性能参数，以路网效率为路网基础性能指标，构建反映扰动事件影响期内路网效率累积动态变化的韧性指标；并基于Sioux Falls网络开展算例研究。算例结果表明：相比传统元胞传输模型，提出的动态分流元胞传输模型通过设置交叉口动态分流参数，建立出行决策行为与元胞流量传输的动态耦合关系和路径流量变化与交叉口元胞分流比例的自洽机制，可准确描述路网实际流量分布状态；提出的基于路网效率的韧性指标可全面反映扰动事件发生后路网性能退化到恢复全过程的动态累积性能，直观展示路网抵御扰动并从扰动中恢复的能力，契合韧性内涵；韧性评估中若忽视出行决策行为潜在影响，将获得次优甚至明显偏离实际的方案或结果。     

TOPSIS在山区铁路线路方案比选中的二次改进

为克服传统TOPSIS(逼近理想解排序法)在山区铁路线路方案比选中不能排除指标间相关性干扰、易使决策工作复杂化的缺点,同时为能充分考虑决策工作的不确定性特征,首先,以马氏距离代替传统TOPSIS中的欧氏距离,实现第一次改进;接着,以相关系数矩阵代替马氏距离中的协方差矩阵,实现第二次改进;然后,运用语言类模糊数、区间数、...     

在役钢筋混凝土桥梁结构的可靠度评估研究

我国现有大量的钢筋混凝土桥梁结构,随着服役时间的不断延长,均存在着不同程度的老化和破坏现象,因此对这些桥梁结构进行可靠度评估就显得非常重要。从可靠度评估和维修策略、基于时变抗力的可靠度分析、疲劳可靠度和动力可靠度几方面问题出发,对在役钢筋混凝土桥梁结构的可靠度评估进行探讨,可为工程实践提供有意义的参考。     

基于地形自适应的货运索道路径自动规划方法

为降低货运索道路径规划工作的时间和经济成本,综合考虑地理信息、工程实际情况和索道架设与运营成本等多方面因素,提出了索道路径规划要求,形成自动化路径规划的技术流程. 针对索道架设要求,提出了基于聚类分簇思想的上、下料点自动筛选方法,实现索道对公路的避让;并根据三维地形数据提出了基于地形自适应的索道支架位置搜索方法,搜索的支架可保证索道承载索与地面的间距满足施工要求;通过支架位置优化,减少支架数量,实现索道成本的降低. 对实际工程的路径规划计算应用表明:该规划方法可在约半个小时的时间内自动获得的上千条索道路径及支架架设方案,规划速度快,数据分析全面.      

基于FCE-DEA-AHP的城市物流绿色度评价研究

针对城市物流的绿色化发展问题,运用层次分析法对城市物流绿色化体系进行划分,在此基础上构建模糊综合评判模型,利用数据包络分析法把多个城市物流在各单因素指标的绿色度表现量化,并结合相应各指标权重进行综合评价和排序,最后通过实例印证评价方法的直观性和高效性.     

城市交叉口交通控制模型的退化研究

针对交叉口交通控制模型在理论研究中效果明显,在实际应用时经常出现模型失配的问题,本文提出交通控制模型的模型退化概念.构建具有多控制变量的交叉口交通控制模型,分析导致模型退化的原因并给出退化路径,利用OSP(Open Simulation Platform)在线交通仿真平台对交通控制模型退化的各阶段模型的典型控制策略进行...     

基于TOPSIS的高速公路软基处理方案评价

为了提高高速公路软基处理方案评价的科学性并实现对预选方案的优劣排序,在遵循方案评价的基本原理及相关要求的基础上,提出基于TOPSIS的高速公路软基处理方案评价方法,建立了高速公路软基处理方案评价模型,并对佛山市一环路进行实例分析,验证了该评价方法的可行性.     

基于GA-PSO混合优化的BPNN车速预测方法

BP神经网络(BPNN)已经用于车速预测方面的研究.针对BPNN不同的初始权值和阈值会影响车速预测精度的问题,提出一种基于GA-PSO混合优化的BPNN车速预测方法.以北工大西门到百葛桥为研究路径,构建基于BPNN的车速预测模型;将遗传算法(GA)和粒子群算法(PSO)的寻优过程进行融合,通过逐次迭代取最优的方式确定BPNN的最优初始权值和阈值,以此设计基于GA-PSO混合优化的BPNN车速预测方法.最后,以所选路径为对象,利用基于GA-BPNN的预测法、基于PSO-BPNN的预测法,以及提出的方法对车速进行了实验预测.结果表明,相较于前两种车速预测改进方法,本文方法的平均车速预测误差分别降低了37.1%和24.1%,有效地提高了车速的预测精度.     

Approach for Reliability Evaluation of Cross-Linked Polyethylene Under Combined Thermal and Vibration Stresses

Based on Wiener process model, a new approach for reliability evaluation of cross-linked polyethylene(XLPE) is proposed to improve the lifetime evaluation reliability of XLPE under multi-stressing conditions and study the failure probability distribution. In this paper, two accelerated aging tests are carried out under combined thermal and vibration conditions. The volume resistance degradation data of XLPE samples are tested with a24 h interval under the accelerated stressing conditions at(130℃, 12 m/s~2) and(150℃, 8.5 m/s~2), respectively.Nonlinear degradation data obtained from the experiment are transformed to linear intermediate-variable values using time scaling function, and then linearized degradation data are calculated and evaluated on the basis of linear Wiener process model. Considering traditional Arrhenius equation and inverse power criterion, parameters of the linear Wiener model are estimated according to the maximum likelihood function. The relationship curves on probability density and reliability are given, and the lifetime distribution of XLPE under different stressing conditions is also obtained for evaluating the reliability of XLPE insulation. Finally, the life expectancy of XLPE is 17.9 a under an allowance temperature of 90℃ and an actual vibration acceleration of 0.5 m/s~2. The approach and results in this paper may be used for reliability assessment of high-voltage multiple samples or apparatuses.     

交通路况感知下的自适应动态路径规划方法

针对传统路径规划算法在动态网络中的时效性和可用性不足，本文提出一种适用于时变 路网环境下的自适应动态路径规划方法。通过引入动态网络流式图划分思想，构建一种分层路 网的状态树索引，有效降低了动态路网中路径查找的计算代价，并扩展了传统路径规划算法在动 态路网中的普适性。在此基础上，将区域路况的时空变化信息融合到索引树中，进一步提出一种 基于时空层次网络的路径映射方法。并按照访问节点的距离逐步收缩最小包含区域来减少路径 查找视野，将路径查找过程转化为在层次图中的小范围寻址。为适应路网动态变化特征，路径映 射采用多路并行的双向探测策略，使得路径搜索迅速收敛于一个最优解，在动态路况变化和旅行 代价之间寻求平衡。最后，结合北京市实时交通路网数据集进行实验评估，在查询性能和自适应 调整方面验证了所提出方法的有效性。