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Journal of Traffic and Transportation Engineering(English Edition) 2023年

作者： Xu Zhang Shunying Ji Yang Feng Yongjun Li chunfa zhao State Key Laboratory of Traction Power， Southwest Jiaotong University State Key Laboratory of Structural Analysis for Industrial Equipment， Dalian University of Technology School of Civil and Transportation Engineering， Guangdong University of Technology

Railway ballast is easily contaminated by different fouling material and the fouled ballast always causes the deterioration of railway track. Many previous studies focused on the effect of a certain kind of fouling material on ballast performance， but few studies compared the influence of different fouling material. This paper presents a series of direct shear tests on the clean ballast and the fouled ballast mixed with coal fines or sand to understand the effects of different fouling material. A unified empirical model is proposed to well capture the shear stress-displacement responses of the clean and fouled ballast. Empirical equations are also obtained to characterize the variation of the nonlinear shear strength envelope of the fouled ballast with the fouling content. Based on these equations， a simple method is proposed to predict the shear strength of the fouled ballast using the shear test results of clean ballast. The measured results demonstrate significant differences between the effects of coal fines and sand on the shear behaviors of ballast， to which particular attention should be paid in order to take targeted maintenance measures for the fouled ballast. The mechanisms for the different effects of coal fines and sand are also analyzed to understand the roles that various fouling material plays in the fouled ballast.

关键词：

Discrete element modelling of railway ballast performance considering particle shape and rolling resistance

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Railway Engineering Science 2020年第4期28卷 382-407页

作者： Yunlong Guo chunfa zhao Valeri Markine Can Shi Guoqing Jing Wanming Zhai Faculty of Civil Engineering and Geosciences Delft University of Technology2628CN DelftThe Netherlands Train and Track Research Institute State Key Laboratory of Traction PowerSouthwest Jiaotong UniversityChengdu 610031China School of Civil Engineering Beijing Jiaotong UniversityBeijing 100044China

To simulate ballast performance accurately and efficiently,the input in discrete element models should be carefully selected,including the contact model and applied particle shape.To study the effects of the contact model and applied particle shape on the ballast performance(shear strength and deformation),the direct shear test(DST)model and the large-scale process simulation test(LPST)model were developed on the basis of two types of contact models,namely the rolling resistance linear(RRL)model and the linear contact(LC)model.Particle shapes are differentiated by clumps.A clump is a sphere assembly for one ballast particle.The results show that compared with the typical LC model,the RRL method is more efficient and realistic to predict shear strength results of ballast assemblies in DSTs.In addition,the RRL contact model can also provide accurate vertical and lateral ballast deformation under the cyclic loading in LPSTs.

关键词： Discrete element method Ballast performance Boundary condition Rolling resistance Direct shear test Lateral displacement

Temperature-induced deformation of CRTS II slab track and its effect on track dynamical properties

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Science China(Technological Sciences) 2014年第10期57卷 1917-1924页

作者： SONG XiaoLin zhao chunfa ZHU XiaoJia State Key Laboratory of Traction Power Southwest Jiaotong University

Two finite-element models of the CRTS II slab track are presented to simulate temperature-induced deformations of the concrete track slab with no deterioration or with a deteriorated cement asphalt mortar(CAM).One model,which considers the fully bonding interface between the slab and the CAM layer,could applied to a track that is in good condition;the other model uses cohesive zone elements to simulate the deteriorated CAM with some possible interfacial separation and slip.Utilizing both of the models,temperature-induced warp deformations of track under various temperature loads are investigated.The influence of temperature deformation on the dynamic properties of the track is analyzed based on the train-track coupled dynamics.Numerical results show that the deteriorated CAM layer can significantly increase temperature deformations of a CRTS II track slab,which would produce tiny rail irregularities.There are clear differences between the deformation shapes of the track slabs that have an inseparable mortar layer and those have a separable mortar layer.The track slab with a deteriorated mortar layer showed more open curl distortion than the track slab in good condition.The dynamical response index of the slab track is intensified to a certain level due to the temperature deformation;with an increase of the train speed,the track dynamical responses increased linearly.However,rail irregularities due to the temperature deformations are very tiny.Even if a track is exposed to extreme temperature loads and the mortar layer is deteriorated,temperature deformation can have a negligible effect on the track’s dynamical properties.

关键词：温度变形板式轨道 CRTS 动力学性能列车运行速度有限元模型界面分离轨道板

A Modern Method for Analyzing Thermal Energy System with System State Equation and Analytical Formula of Performance Index

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Journal of Thermal Science 2007年第1期16卷 90-96页

作者： chunfa ZHANG Liping LI Huijie WANG Ning zhao School of Energy and Power North China Electric Power University Baoding 071003

这份报纸探讨开火煤的电源联合起来的全面表演分析。从系统工程的观点，热植物系统的一个一般蒸气水分发方程被介绍。这个系统状态方程是联合系统的准确表情拓扑的结构和系统性质。通过合适的数学变换，在主要系统和辅助系统之间的内部... 详细信息

这份报纸探讨开火煤的电源联合起来的全面表演分析。从系统工程的观点，热植物系统的一个一般蒸气水分发方程被介绍。这个系统状态方程是联合系统的准确表情拓扑的结构和系统性质。通过合适的数学变换，在主要系统和辅助系统之间的内部关系和相互作用被揭示，它的一般形式被给。为热发电厂的热消费率的一个分析公式是方程的一直接水果，它极大地便于复杂热系统的联机分析并且优化。在获得技术的现代数据的帮助下，新途径基于热力学的第一条法律是传统的分析方法的完美的扩展。

关键词：热力系统性能指标分析方法系统状态方程解析式

Functionalizing DNA nanostructures with natural cationic amino acids

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Bioactive Materials 2021年第9期6卷 2946-2955页

作者： Dong Wang chunfa Chen Qian Liu Qianwen zhao Di Wu Yue Yuan Chaowang Huang Xiaorong Sun Chunji Huang David Tai Leong Guansong Wang Hang Qian Institute of Respiratory Diseases Xinqiao HospitalThird Military Medical University183 Xinqiao StreetChongqing400037China Laboratory of Pharmacy and Chemistry And Laboratory of Tissue and Cell BiologyLab Teaching&Management CenterChongqing Medical UniversityChongqing400016China Basic Medical College Third Military Medical UniversityChongqing400038China Department of Chemical and Biomolecular Engineering National University of SingaporeSingapore Department of Respiratory Medicine Jinling HospitalNanjingJiangsu210002China

Complexing self-assembled DNA nanostructures with various functional guest species is the key to unlocking new and exciting biomedical applications.Cationic guest species not only induce magnesium-free DNA to self-assemble into defined structures but also endow the final complex nanomaterials with new properties.Herein,we propose a novel strategy that employs naturally occurring cationic amino acids to induce DNA self-assembly into defined nanostructures.Natural L-arginine and L-lysine can readily induce the assembly of tile-based DNA nanotubes and DNA origami sheets in a magnesium-free manner.The self-assembly processes are demonstrated to be pH-and concentration-dependent and are achieved at constant temperatures.Moreover,the assembled DNA/amino acid complex nanomaterials are stable at a physiological temperature of 37◦C.Substituting L-arginine with its D form enhances its serum stability.Further preliminary examination of this complex nanomaterial platform for biomedical applications indicates that DNA/amino acids exhibit distinct cellular uptake behaviors compared with their magnesium-assembled counterparts.The nanomaterial mainly clusters around the cell membrane and might be utilized to manipulate molecular events on the membrane.Our study suggests that the properties of DNA nanostructures can be tuned by complexing them with customized guest molecules for a designed application.The strategy proposed herein might be promising to advance the biomedical applications of DNA nanostructures.

关键词： DNA nanostructures Noncanonical DNA self-Assembly Amino acids Isothermal self-assembly

高速铁路级配碎石颗粒三维形态特征多尺度分析

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岩石力学与工程学报 2022年第S1期41卷 3091-3100页

作者：陆瑞罗强刘钢赵春发何心一西南交通大学土木工程学院四川成都610031 西南交通大学高速铁路线路工程教育部重点实验室四川成都610031 西华大学土木建筑与环境学院四川成都610039 西南交通大学牵引动力国家重点实验室四川成都610031

高速铁路路基级配碎石颗粒形态对宏观力学性质具有显著影响,合理量化颗粒三维形态特征是粗颗粒填料细观机制研究的基础性工作。采用激光扫描仪获取2.36~31.5mm粒径范围7个粒组共计700个碎石颗粒的点云数据,重构形成三维网格模型;引入描... 详细信息

高速铁路路基级配碎石颗粒形态对宏观力学性质具有显著影响,合理量化颗粒三维形态特征是粗颗粒填料细观机制研究的基础性工作。采用激光扫描仪获取2.36~31.5mm粒径范围7个粒组共计700个碎石颗粒的点云数据,重构形成三维网格模型;引入描述颗粒表面凹凸特征的主曲率均值平方根RMS,基于颗粒网格模型平滑处理及RMS曲率分布特征,分别定义以棱角区域点云数量占比表征的棱角参数、以平滑前后模型RMS差异描述的纹理参数。结合长、中、短轴相互关系所描述的形状参数,形成刻画碎石颗粒多尺度形态特征的指标体系;通过选取典型形态特征颗粒,验证所建立的指标体系具有良好形态甄别能力;根据所扫描碎石颗粒的统计分析,不同粒组碎石颗粒的形状、棱角、纹理指标基本呈正态分布特征,随粒径增大,块状颗粒占比提高,棱角和纹理特征愈加突出。研究成果可为从宏、中、细观3个尺度量化评价颗粒形态特征提供参考。

关键词：土力学级配碎石颗粒三维形态特征 RMS曲率棱角纹理

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现代轨道交通工程科技前沿与挑战

西南交通大学学报 2016年第2期51卷 209-226页

作者：翟婉明赵春发西南交通大学牵引动力国家重点实验室

围绕现代轨道交通的四大重点领域:高速铁路、重载铁路、城市轨道交通和磁悬浮交通,介绍了当前国内外最新发展动态,特别是我国轨道交通发展现状及其在国际上所处的地位与水平.结合轨道交通工程学科发展趋势与应用需求,分析了轨道交通工... 详细信息

围绕现代轨道交通的四大重点领域:高速铁路、重载铁路、城市轨道交通和磁悬浮交通,介绍了当前国内外最新发展动态,特别是我国轨道交通发展现状及其在国际上所处的地位与水平.结合轨道交通工程学科发展趋势与应用需求,分析了轨道交通工程建设与运营过程中涉及系统安全性、运营可靠性和环境适应性等方面的主要技术瓶颈,指出了高速铁路、重载铁路、城市轨道交通和磁悬浮交通领域当前值得关注的前沿科学问题和技术挑战,为今后深入开展轨道交通科学技术研究(特别是针对处于快速发展期的中国轨道交通科技研究)提供有益参考.

关键词：铁道工程轨道交通发展动态科技前沿技术挑战述评

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两种中低速磁浮车辆动力学性能仿真对比分析

机械工程学报 2023年第10期59卷 311-322页

作者：胡帛茹赵春发蔡文锋龚俊虎冯洋西南交通大学牵引动力国家重点实验室成都610031 中铁二院工程集团有限责任公司成都610031 中铁磁浮交通投资建设有限公司武汉430060

针对采用空簧端置式悬浮架的传统中低速磁浮车辆和采用空簧中置式悬浮架的新型中低速磁浮车辆,建立考虑主动悬浮控制的车辆动力学模型,仿真分析两种磁浮车辆直线运行和平面曲线通过时的动力学响应。结果表明,新型磁浮车辆直线运行的动... 详细信息

针对采用空簧端置式悬浮架的传统中低速磁浮车辆和采用空簧中置式悬浮架的新型中低速磁浮车辆,建立考虑主动悬浮控制的车辆动力学模型,仿真分析两种磁浮车辆直线运行和平面曲线通过时的动力学响应。结果表明,新型磁浮车辆直线运行的动力学性能优于传统磁浮车辆,在时速160 km以内新型磁浮车辆的运行平稳性均为优秀;速度大于120 km/h以后,传统磁浮车辆直线运行的动力学性能明显恶化,横向平稳性达不到优秀级。通过半径300 m及以上平面曲线时,两种磁浮车辆的动力学响应差别不大;在半径50m无超高平面曲线上,传统磁浮车辆发生了磁轨横向机械碰撞,而新型磁浮车辆可无接触通过;在半径100 m有超高平面曲线上,新型磁浮车辆的动力学性能劣于传统磁浮车辆,主要表现为缓和曲线段悬浮间隙波动和电磁铁横移量更大,磁轨间发生横向碰撞的风险较大。

关键词：磁浮车辆悬浮架反馈控制多体动力学运行平稳性曲线通过

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铁路碎石道砟静态压碎行为数值模拟

西南交通大学学报 2015年第1期50卷 137-143页

作者：张徐赵春发翟婉明西南交通大学牵引动力国家重点实验室四川成都610031

为揭示碎石道砟静态受压力学行为与破碎机理,用激光扫描仪获得道砟的真实几何形态,采用球形单元构建了道砟的离散元模型;通过定义单元间接触与黏结行为,模拟了30-60 mm粒径道砟的静态压碎过程,分析了压碎过程中载荷-位移响应以及内部力... 详细信息

为揭示碎石道砟静态受压力学行为与破碎机理,用激光扫描仪获得道砟的真实几何形态,采用球形单元构建了道砟的离散元模型;通过定义单元间接触与黏结行为,模拟了30-60 mm粒径道砟的静态压碎过程,分析了压碎过程中载荷-位移响应以及内部力链和黏结断裂的分布与演化.结果表明：道砟静态压碎特征强度的离散性大且服从Weibull分布,这与已有试验结果一致;初始加载时,尖锐棱角和表面不平整导致道砟表面接触点应力集中与局部压碎,引起道砟翻转及接触状态变化,内部力链分布随之变化,载荷出现短暂回落;道砟稳定弹性变形阶段,部分单元间的接触力随载荷增大逐渐超过黏接强度,出现黏结断裂和局部微裂纹;当黏结断裂数量急剧增加到一定规模时,内部裂纹快速扩展,道砟最终劈裂破碎.

关键词：铁路道砟压碎离散元法力链黏结断裂

循环荷载频率对高速铁路有砟道床累积变形行为的影响

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中国铁道科学 2017年第1期38卷 1-8页

作者：张徐赵春发翟婉明西南交通大学牵引动力国家重点实验室四川成都610031

为研究高速铁路有砟道床因反复承受高频率的列车荷载作用而劣化及累积变形的规律,利用离散元分析软件PFC并考虑道砟颗粒的真实几何形态,建立高速铁路有砟道床三维离散元模型,模拟分析不同频率、不同幅值循环简谐荷载作用下道床的累积变... 详细信息

为研究高速铁路有砟道床因反复承受高频率的列车荷载作用而劣化及累积变形的规律,利用离散元分析软件PFC并考虑道砟颗粒的真实几何形态,建立高速铁路有砟道床三维离散元模型,模拟分析不同频率、不同幅值循环简谐荷载作用下道床的累积变形,并通过统计分析道砟颗粒的重排行为,从细观层面探讨荷载频率对道床累积变形行为的影响机理。开展高速铁路有砟道床的室内实尺模型累积变形试验,验证道床离散元模型的合理性和模拟结果的可靠性。结果表明:在相近的荷载工况下,模拟分析获得的道床累积变形结果与实尺模型试验结果较为吻合;循环简谐荷载的频率低于15 Hz时,道床的累积变形主要由道砟颗粒间的相对接触滑动引起,但累积变形及其增长速率均不大;当荷载频率提高至20 Hz以上时,道床的累积变形及其增长速率随荷载频率的提高而快速增大,且其主要原因是道砟颗粒发生了剧烈转动。

关键词：高速铁路有砟道床循环荷载频率累积变形颗粒重排离散单元法