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A damage detection method using fractal theory

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A damage detection method using fractal theory

第六届国际振动工程会议

作者： Yong Huang 1 Hui Li 1 Jinping Ou 1 2 1school of civil engineering Harbin Institute of Technology Harbin 150090 China 2 school of civil and Hydraulic engineering Dalian University of Technology Dalian 116024 China

Considering that the damage of civil structures usually occurs at local areas and the fractal dimension can insight the local irregularity in geometry of an object, a damage detection approach based on Katz’s estimation of fractal dimension （FD） measure for beam structures is proposed in this study. The angle of rotation of the curve over the entire sliding window is first expressed by FD. An FD-based index for damage localization （FDIDL） is further proposed using the difference of the angle of rotation between two successive points. The relationship between the angle of rotation and the modal strain energy is established and then an FD-based index for estimation of damage extent is presented, which can predict the damage extent. Numerical studies are carried out using a simple supported beam. The results indicate that distinct fluctuations on FDIDL curve just appear at damage locations. Therefore, the FDIDL can localize the damage regardless of single damage location or multi-damage locations. Furthermore, the results for estimation of damage extent indicate that the proposed FD-based damage index for estimation of damage exten（tFDIEDE）can quantify damage extent without realizing the accurate damage length.

关键词： fractal theory damage localization damage extent beam structure

Experimental Study on Bearing Features of Bored Pile under Non-refreezing Condition in Permafrost Region

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Experimental Study on Bearing Features of Bored Pile under N...

第一届交通运输工程国际学术会议

作者： YU Zhi-qiang1, WANG Xu2, and JIANG Dai-jun2 1school of civil engineering, Southwest Jiaotong University, Chengdu 610031, China 2school of civil engineering, Lanzhou Jiaotong University, Lanzhou 730070, China

Facing the problems such as pile cap and bridge pier construction, super structure construction, time limit for construction etc, a key problem is to solve the bearing capacity and deformation of large diameter bored pile under non-refreezing condition. In-situ experiment was carried out at high-temperature in fine-granular frozen soil region of Qinghai-Tibet plateau. On the basis of ground temperature data and in-situ experimental data, the authors analyzed the shaft resistance and tip resistance of the pile under different ground temperature conditions. In the meantime, the authors also analyzed the deformation features of non-refreezing large diameter bored pile in permafrost. The experimental results can be used as some guides and references in the process of pile foundation construction.

关键词： permafrost high temperature fine-granular frozen soil cast-in-place bored pile ground temperature axial bearing features

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铁路环境噪声影响模糊评价新方法

铁道学报 2002年第3期24卷 91-94页

作者：李卫国陈峰石家庄铁道学院土木工程分院河北石家庄050043 北方交通大学土木建筑工程学院北京100044

以加权广义权距离概念为基础 ,结合噪声污染级别特征值法提出一种铁路环境噪声评价的新方法。评价过程中充分利用实际数据所包含的信息 ,使得评价结果科学、分明。与模糊综合多级评判模型的同一应用实例相比较。

关键词：模糊评价加权广义权距离铁路环境噪声评价噪声污染环境影响

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铁路信息资源的层次模型研究

铁道学报 2003年第2期25卷 39-42页

作者：沈永清柯新生李学伟北方交通大学土木建筑工程学院北京100044 北方交通大学经济管理学院北京100044

目前铁路信息资源在不同的维度上进行分层的方法尚存在结构不完善、分层次数不科学、分层标准不统一的问题,降低了信息资源分层的效率系数,使得大量的信息资源的应用不充分或不方便或干脆无法使用。本文在对铁路信息资源现状分析的基础... 详细信息

目前铁路信息资源在不同的维度上进行分层的方法尚存在结构不完善、分层次数不科学、分层标准不统一的问题,降低了信息资源分层的效率系数,使得大量的信息资源的应用不充分或不方便或干脆无法使用。本文在对铁路信息资源现状分析的基础上,借助层次模型理论,提出了铁路信息资源4层次模型,利用映射理论描述了各层次间的映射对应关系,最后分析了该模型在铁路信息资源开发中的应用,以满足铁路信息资源开发利用的需要。

关键词：信息资源层次模型映射理论

桥梁结构极限承载力分析的截面内力塑性系数法

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铁道学报 2002年第4期24卷 97-99页

作者：戴公连曾庆元邹银生中南大学土木建筑学院湖南长沙410075 湖南大学土木工程学院湖南长沙410082

基于 U.L.列式单元增量平衡方程 ,提出了一种建立钢筋混凝土梁单元弹塑性刚度矩阵的新方法——单元节点截面内力塑性系数法 ,并编制了相应的计算程序。用该方法计算了两个大型单拱面预应力混凝土系杆拱桥模型。结果表明。

关键词：桥梁结构极限承载力截面内力塑性系数法弹塑性分析模型试验

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铁路桥梁制动力调节体系的研究

铁道学报 2002年第3期24卷 78-83页

作者：张俊平高向宇周福霖廖蜀樵广州大学土木工程学院广东广州510405 铁道第一勘察设计院甘肃兰州730000

基于铅芯橡胶支座的性能 ,提出利用铅芯屈服前刚度合理调节列车制动力、利用铅芯屈服后刚度进行隔震的思路 ,并通过静力试验、动力特性测试及模拟地震振动台试验予以验证。试验结果表明 :设置橡胶支座后 ,可以有效地调整各墩台的综合刚... 详细信息

基于铅芯橡胶支座的性能 ,提出利用铅芯屈服前刚度合理调节列车制动力、利用铅芯屈服后刚度进行隔震的思路 ,并通过静力试验、动力特性测试及模拟地震振动台试验予以验证。试验结果表明 :设置橡胶支座后 ,可以有效地调整各墩台的综合刚度 ,按设计意图合理分配制动力 ;与传统支座桥梁相比 ,橡胶支座多跨简支模型桥梁的动力反应呈全桥一致反应 ,隔震效果显著 ,地震响应得以大幅度减小。

关键词：调节体系铁路桥梁铅芯橡胶支座制动力振动台试验地震响应

Optimization of Selecting PGI Sign Locations Based on Parking Guidance Behavior Survey

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Optimization of Selecting PGI Sign Locations Based on Parkin...

第一届交通运输工程国际学术会议

作者： ZHANG Bao-yu1, YAN Ke-fei2, and ZHOU Xiang-ting2 1school of civil engineering & Architecture, Chongqing Jiaotong University, Chongqing, China, 400074.2school of Transportation engineering, Tongji University, Shanghai, China, 201804

In order to conveniently locate available parking spaces in city CBD, Parking Guidance Information System （PGIS） is established to provide real-time parking information to drivers. But locations of PGI signs are mostly selected by subjective experience. The paper presents PGIS application in Xujiahui area of Shanghai, based on parking guidance behavior survey. The amount of guidance information is the objective function. An optimization model is established with three constraints: the total number of PGI signs;3 parking lots at most are displayed at each intersection approach;and the information of each parking lots involved in PGIS should be displayed on PGI signs at least once. Genetic Algorithm is applied to solve this model. Finally, the scale, locations and their functions of Xujiahui PGI signs can be obtained. The result shows that the model is applicable in practice.

关键词： parking guidance optimization PGI signs locations

IONOSPHERIC EFFECTS ON GPS NAVIGATION IN LOW-LATITUDE AREA

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IONOSPHERIC EFFECTS ON GPS NAVIGATION IN LOW-LATITUDE AREA

第一届交通运输工程国际学术会议

作者： GAO Shan1, 2 and CHEN Wu2 1school of civil engineering, Southwest Jiaotong University, Chengdu, Sichuan, China, 610031 2Dept. of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University, Hong Kong

Ionospheric effects are the major constraints for GPS navigation. Especially, at low latitude, ionospheric delay varies greatly both in space and time. Even for short baselines, ionospheric effects cannot be cancelled out with double difference algorithm. Strong ionospheric disturbances are also observed in the region. In this paper, ionospheric behavior in Hong Kong is investigated by using a dense reference network. The effects of ionospheric disturbances on GPS receiver, such as loss of lock, gross error and measurement noise are studied.

关键词： GPS navigation ionospheric delay loss of lock cycle slip

轨道交通线路专业基于ActiveX技术进行AutoCAD二次开发的研究

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铁道学报 2002年第1期24卷 87-92页

作者：万传风魏庆朝吴爽李大勇北方交通大学土木建筑学院北京100044 北京市城建设计研究院北京100037

对 Auto CAD的二次开发工具作了系统、全面的介绍与比较 ,从中选定 Active X技术 ,阐述了选择 VisualBasic作为开发语言的原因 ,给出了应用 Active X技术开发 Auto CAD的几段原代码 ,并针对北京城市铁路的部分区段 (西直门—回龙观 )进... 详细信息

对 Auto CAD的二次开发工具作了系统、全面的介绍与比较 ,从中选定 Active X技术 ,阐述了选择 VisualBasic作为开发语言的原因 ,给出了应用 Active X技术开发 Auto CAD的几段原代码 ,并针对北京城市铁路的部分区段 (西直门—回龙观 )进行了应用 ,证明程序的计算速度快捷、结果准确。

关键词：城市铁路轨道交通线路专业 AutoCAD二次开发 ActiveX技术 Visual Basic编程语言