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A frequency and amplitude dependent model of rail pads for the dynamic analysis of train-track interaction

Science China(Technological Sciences) 2015年第2期58卷 191-201页

作者： ZHU Sheng Yang cai cheng biao LUO Zhen LIAO Zhong Qi State Key Laboratory of Traction Power Southwest Jiaotong University China Railway Construction Heavy Industry Co. Ltd. China Railway Longchang Materials Co. Ltd.

A frequency and amplitude dependent model is used to describe the complex behavior of rail pads. It is implemented into the dynamic analysis of three dimensional coupled vehicle-slab track （3D-CVST） systems. The vehicle is treated as a 35-degree- of-freedom multi-body system, and the slab track is represented by two continuous Bernoulli-Euler beams supported by a se- ries of elastic rectangle plates on a viscoelastic foundation. The rail pad model takes into account the influences of the excita- tion frequency and of the displacement amplitude through a fractional derivative element, and a nonlinear friction element, re- spectively. The Granwald representation of the fractional derivatives is employed to numerically solve the fractional and non- linear equations of motion of the 3D-CVST system by means of an explicit integration algorithm. A dynamic analysis of the 3D-CVST system exposed to excitations of rail harmonic irregularities is primarily carried out, which reveals the dependence of stiffness and damping on excitation frequency and displacement amplitude. Subsequently, sensitive analyses of the model parameters are investigated by conducting the dynamic analysis of the 3D-CVST system subjected to excitations of welded rail joint irregularities. Following this, parameters of the rail pad model are optimized with respect to experimental values. For elu- cidation, the 3D-CVST dynamic model incorporated with the rail pads model is used to calculate the wheel/rail forces induced by excitations of measured random track irregularities. Further, the numerical results are compared with experimental data, demonstrating the reliability of the proposed model.

关键词： rail pads vehicle-track coupled dynamics frequency dependent amplitude dependent

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Safety threshold of high-speed railway pier settlement based on train-track-bridge dynamic interaction

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Science China(Technological Sciences) 2015年第2期58卷 202-210页

作者： CHEN Zhao Wei ZHAI Wan Ming cai cheng biao SUN Yu State Key Laboratory of Traction Power Southwest Jiaotong University

This paper presents a method to determine the safety threshold of bridge pier settlement in high-speed *** analytical expression of the mapping relationship between the pier settlement and the rail deformation is derived theoretically for the double block ballastless track-bridge *** adopting the superposition of the track random irregularity and the rail deformation caused by the pier settlement as the excitation inputs,the variations of vehicle dynamics indices with pier settlement are comparatively ***,the safety threshold of the bridge pier settlement is obtained according to the limit of vehicle running safety and ride comfort indices of the high-speed *** show that the dynamics indices of different trains have different sensitivities to the pier settlement,and the train CRH2C is the most sensitive one among all the types of Chinese high-speed *** passing through the bridges in common span with pier settlement at the speed of 250–350 km/h,the trains suffer the low-frequency excitations,and the vertical acceleration of car body is most sensitive to the pier settlement of all the dynamics *** the car body vertical acceleration just exceeds the allowable limit,the critical settlement value is 23.4 mm,which is much bigger than the pier differential settlement limit in the current code for Chinese high-speed railways.

关键词： high-speed railway pier settlement safety threshold dynamic characteristics train-track-bridge dynamic interaction

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弹性支承块式无砟轨道结构参数动力学优化设计

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铁道学报 2011年第1期33卷 69-75页

作者：蔡成标徐鹏西南交通大学牵引动力国家重点实验室四川成都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

建立车辆-弹性支承块式无砟轨道耦合动力学模型。模拟落轴试验荷载条件,分析轨下刚度与块下刚度的匹配关系,得出轨下刚度与块下刚度的合理取值范围。在轨道刚度确定的前提下,提出不同运营条件下满足动态轨距扩大限值的弹性支承块式无砟... 详细信息

建立车辆-弹性支承块式无砟轨道耦合动力学模型。模拟落轴试验荷载条件,分析轨下刚度与块下刚度的匹配关系,得出轨下刚度与块下刚度的合理取值范围。在轨道刚度确定的前提下,提出不同运营条件下满足动态轨距扩大限值的弹性支承块式无砟轨道合理结构参数。评估不同半径曲线上铺设弹性支承块式无砟轨道时重载货车和快速客车的运行安全性和舒适性。研究隧道内弹性支承块式无砟轨道与隧道外有砟轨道过渡段动力学问题,结果表明:将有砟轨道向隧道内延伸一定长度可明显改善连接处轨枕的受力状况,同时使支承块免受雨水侵蚀。延伸段长度以10～20 m为宜。

关键词：车辆-轨道耦合动力学弹性支承块式无砟轨道结构参数优化设计

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高速铁路框架型板式轨道动力学分析

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振动工程学报 2011年第2期24卷 164-169页

作者：蔡成标徐鹏西南交通大学牵引动力国家重点实验室四川成都610031

建立了高速列车-框架型板式轨道的动力学模型。基于弹性薄板振动理论和加权余量法,推导了框架型轨道板关于振型坐标的常微分方程。对比分析了运行速度为300 km/h的CRH 2-300动车组作用下框架型和平板型板式轨道动力响应,结果表明:两种... 详细信息

建立了高速列车-框架型板式轨道的动力学模型。基于弹性薄板振动理论和加权余量法,推导了框架型轨道板关于振型坐标的常微分方程。对比分析了运行速度为300 km/h的CRH 2-300动车组作用下框架型和平板型板式轨道动力响应,结果表明:两种轨道结构的钢轨垂向位移、钢轨支点反力差别不大,框架型板式轨道的轨道板垂向位移、CA砂浆动应力均大于平板型。分析了CA砂浆弹性模量、板下胶垫刚度对框架型板式轨道动力响应的影响,计算了框架型轨道板的动应力分布,结果表明:随CA砂浆弹性模量的增大,框架型轨道板垂向位移减小,CA砂浆动应力增大,对钢轨垂向位移和钢轨支点反力影响不大;增设板下胶垫可以有效降低CA砂浆动应力;框架型轨道板最大拉应力小于混凝土抗拉强度标准值,可保证强度。

关键词：列车框架型板式轨道开孔板动力响应

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Reshaping Li–Mg hybrid batteries:Epitaxial electrodeposition and spatial confinement on MgMOF substrates via the lattice‐matching strategy

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Carbon Energy 2024年第8期6卷 248-261页

作者： Yongqin Wang Fulin cheng Jiawen Ji Chenyang cai Yu Fu School of Materials Science and Engineering Co‐Innovation Center of Efficient Processing and Utilization of Forest ResourceNanjing Forestry UniversityNanjingJiangsuChina

The emergence of Li–Mg hybrid batteries has been receiving attention,owing to their enhanced electrochemical kinetics and reduced ***,the persistent challenge of uneven Mg electrodeposition remains a significant impediment to their practical ***,we developed an ingenious approach that centered around epitaxial electrocrystallization and meticulously controlled growth of magnesium crystals on a specialized MgMOF *** chosen MgMOF substrate demonstrated a robust affinity for magnesium and showed minimal lattice misfit with Mg,establishing the crucial prerequisites for successful heteroepitaxial ***,the incorporation of periodic electric fields and successive nanochannels within the MgMOF structure created a spatially confined environment that considerably promoted uniform magnesium nucleation at the molecular *** inspiration from the“blockchain”concept prevalent in the realm of big data,we seamlessly integrated a conductive polypyrrole framework,acting as a connecting“chain,”to interlink the“blocks”comprising the MgMOF *** innovative design significantly amplified charge‐transfer efficiency,thereby increasing overall electrochemical *** resulting architecture(MgMOF@PPy@CC)served as an exceptional host for heteroepitaxial Mg electrodeposition,showcasing remarkable electrostripping/plating kinetics and excellent cycling ***,a symmetrical cell incorporating the MgMOF@PPy@CC electrode demonstrated impressive stability even under ultrahigh current density conditions(10mAcm–2),maintaining operation for an extended 1200 h,surpassing previously reported ***,on coupling the MgMOF@PPy@CC anode with a Mo_(6)S_(8) cathode,the assembled battery showed an extended lifespan of 10,000 cycles at 70 C,with an outstanding capacity retention of 96.23%.This study provides a fresh perspective on the rational design of epitaxial electrocrystallizat

关键词： epitaxial electrodeposition lattice‐matching strategy Li-Mg hybrid batteries MOF substrate spatial confinement

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Solving Multi-Objective Vehicle Routing Problems with Time Windows: A Decomposition-Based Multiform Optimization Approach

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Tsinghua Science and Technology 2024年第2期29卷 305-324页

作者： Yiqiao cai Zifan Lin Meiqin cheng Peizhong Liu Ying Zhou Xiamen Key Laboratory of Data Security and Blockchain Technology College of Computer Science and TechnologyHuaqiao UniversityXiamen361021China College of Engineering Huaqiao UniversityQuanzhou362000China School of Computer Sciences Shenzhen Institute of Information TechnologyShenzhen518000China

In solving multi-objective vehicle routing problems with time windows (MOVRPTW),most existing algorithms focus on the optimization of a single problem formulation. However,little effort has been devoted to exploiting valuable knowledge from the alternate formulations of MOVRPTW for better optimization performance. Aiming at this insufficiency,this study proposes a decomposition-based multi-objective multiform evolutionary algorithm (MMFEA/D),which performs the evolutionary search on multiple alternate formulations of MOVRPTW simultaneously to complement each other. In particular,the main characteristics of MMFEA/D are three folds. First,a multiform construction (MFC) strategy is adopted to construct multiple alternate formulations,each of which is formulated by grouping several adjacent subproblems based on the decomposition of MOVRPTW. Second,a transfer reproduction (TFR) mechanism is designed to generate offspring for each formulation via transferring promising solutions from other formulations,making that the useful traits captured from different formulations can be shared and leveraged to guide the evolutionary search. Third,an adaptive local search (ALS) strategy is developed to invest search effort on different alternate formulations as per their usefulness for MOVRPTW,thus facilitating the efficient allocation of computational resources. Experimental studies have demonstrated the superior performance of MMFEA/D on the classical Solomon instances and the real-world instances.

关键词： MOVRPTW multiform optimization multiform construction knowledge transfer adaptive local search

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Emerging role of regulated cell death in intestinal failure-associated liver disease

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Hepatobiliary & Pancreatic Diseases International 2024年第3期23卷 228-233页

作者： Si-Yang cheng Lu Jiang Ying Wang Wei cai Department of Pediatric Surgery Xinhua HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai 200092China Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition Shanghai 200092China Shanghai Institute for Pediatric Research Shanghai 200092China Division of Pediatric Gastroenterology and Nutrition Xinhua HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai 200092China

Intestinal failure-associated liver disease(IFALD)is a common complication of long-term parenteral nutrition that is associated with significant morbidity and *** is mainly characterized by cholestasis in children and steatohepatitis in ***,there is no effective approach to prevent or reverse the *** cell death(RCD)represents a fundamental biological paradigm that determines the outcome of a variety of liver *** cell death is reclassified into several types,based on the mechanisms and morphological *** evidence has linked different modes of RCD,such as apoptosis,necroptosis,ferroptosis,and pyroptosis to the pathogenesis of liver *** studies have shown that different modes of RCD are present in animal models and patients with *** the pathogenic roles of cell death may help uncover the underlying mechanisms and develop novel therapeutic strategies in *** this review,we discuss the current knowledge on how RCD may link to the pathogenesis of *** highlight examples of cell death-targeted interventions aiming to attenuate the disease,and provide perspectives for future basic and translational research in the field.

关键词： Parenteral nutrition Apoptosis Necroptosis Cholestasis Steatosis

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Geochemistry and origins of hydrogen-containing natural gases in deep Songliao Basin,China:Insights from continental scientific drilling

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Petroleum Science 2024年第2期21卷 741-751页

作者： Shuang-biao Han Chao-Han Xiang Xin Du Lin-Feng Xie Jie Huang cheng-Shan Wang College of Geoscience and Surveying Engineering China University of Mining and TechnologyBeijing100083China State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesBeijing100083China

The different reservoirs in deep Songliao Basin have non-homogeneous lithologies and include multiple layers with a high content of hydrogen *** gas composition and stable isotope characteristics vary significantly,but the origin analysis of different gas types has previously been *** on the geochemical parameters of gas samples from different depths and the analysis of geological settings,this research covers the diverse origins of natural gas in different *** gas components are mainly methane with a small amount of C_(2+),and non-hydrocarbon gases,including nitrogen(N_(2)),hydrogen(H_(2)),carbon dioxide(CO_(2)),and helium(He).At greater depth,the carbon isotope of methane becomes heavier,and the hydrogen isotope points to a lacustrine sedimentary *** increasing depth,the origins of N_(2)and CO_(2)change gradually from a mixture of organic and inorganic to *** origins of hydrogen gas are complex and include organic sources,water radiolysis,water-rock(Fe^(2+)-containing minerals)reactions,and *** shales of Denglouku and Shahezi Formations,as source rocks,provide the premise for generation and occurrence of organic ***,the deep faults and fluid activities in Basement Formation control the generation and migration of mantle-derived *** discovery of a high content of H_(2)in study area not only reveals the organic and inorganic association of natural-gas generation,but also provides a scientific basis for the exploration of deep hydrogen-rich gas.

关键词： Gas compositions Stable isotopes Gas origins Hydrogen gas Songliao Basin

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Hemispherical resonator with low subsurface damage machined by small ball-end fine diamond grinding wheel:A novel grinding technique

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Chinese Journal of Aeronautics 2024年第5期37卷 570-585页

作者： biao QIN Henan LIU Jian cheng Jinchuan TIAN Jiangang SUN Zihan ZHOU Chuanzhen MA Mingjun CHEN State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China Center for Precision Engineering Harbin Institute of TechnologyHarbin 150001China

As for the ultra-precision grinding of the hemispherical fused silica resonator,due to the hard and brittle nature of fused silica,subsurface damage(SSD)is easily generated,which enormously influences the performance of such ***,ultra-precision grinding experiments are carried out to investigate the surface/subsurface quality of the hemispherical resonator machined by the small ball-end fine diamond grinding *** influence of grinding parameters on the surface roughness(SR)and SSD depth of fused silica samples is then *** experimental results indicate that the SR and SSD depth decreased with the increase of grinding speed and the decrease of feed rate and grinding *** addition,based on the material strain rate and the maximum undeformed chip thickness,the effect of grinding parameters on the subsurface damage mechanism of fused silica samples is ***,a multi-step ultra-precision grinding technique of the hemispherical resonator is proposed based on the interaction influence between grinding depth and feed ***,the hemispherical resonator is processed by the proposed grinding technique,and the SR is improved from 454.328 nm to 110.449 nm while the SSD depth is reduced by 94%from 40μm to 2.379μ*** multi-step grinding technique proposed in this paper can guide the fabrication of the hemispherical resonator.

关键词： Fused silica Ultra-precision grinding Hemispherical resonator Subsurface damage Grinding technique

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城市轨道交通低频减振轨道结构研究

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铁道学报 2015年第9期37卷 90-95页

作者：杨吉忠颜华蔡成标中铁二院工程集团有限责任公司科学技术研究院四川成都610031 西南交通大学牵引动力国家重点实验室四川成都610031

针对城市轨道交通常规减振型轨道结构在低频域(<30Hz)范围内因共振放大低频振动的现象,提出一种被动式动力减振轨道结构。基于扩展定点理论和有限单元法,利用最优同调和最优阻尼条件,得到抑制浮置板轨道1阶模态振动的最优刚度和阻尼。... 详细信息

针对城市轨道交通常规减振型轨道结构在低频域(<30Hz)范围内因共振放大低频振动的现象,提出一种被动式动力减振轨道结构。基于扩展定点理论和有限单元法,利用最优同调和最优阻尼条件,得到抑制浮置板轨道1阶模态振动的最优刚度和阻尼。以短型钢弹簧浮置板轨道为例,建立车辆-被动式动力减振浮置板轨道耦合动力学模型。计算结果表明:被动式动力减振浮置板可有效抑制13 Hz(短型浮置板1阶固有频率)附近的振动加速度,质量比为0.2时被动式动力减振浮置板使13Hz处振动降低12dB;被动式动力减振浮置板使弹簧支点反力在13Hz附近的峰值明显降低,有效降低传递至周围建筑物的低频振动;被动式动力减振浮置板轨道结构的质量比越大,其对1阶模态振动的减振效果越好。

关键词：轨道低频被动减振技术共振质量比

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