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Analysis of wheel-rail adhesion redundancy considering the thirdbody medium on the rail surface

Railway Sciences 2024年第2期3卷 156-176页

作者： Chun Tian Gengwei Zhai mengling wu Jiajun Zhou Yaojie Li Institute of Rail Transit Tongji UniversityShanghaiChina

Purpose–In response to the problem of insufficient traction/braking adhesion force caused by the existence of the third-body medium on the rail surface,this study aims to analyze the utilization of wheel-rail adhesion coefficient under different medium conditions and propose relevant measures for reasonable and optimized utilization of adhesion to ensure the traction/braking performance and operation safety of ***/methodology/approach–Based on the PLS-160 wheel-rail adhesion simulation test rig,the study investigates the variation patterns of maximum utilized adhesion characteristics on the rail surface under different conditions of small creepage and large *** statistical analysis of multiple sets of experimental data,the statistical distribution patterns of maximum utilized adhesion on the rail surface are obtained,and a method for analyzing wheel-rail adhesion redundancy based on normal distribution is *** study analyzes the utilization of traction/braking adhesion,as well as adhesion redundancy,for different medium under small creepage and large slip *** on these findings,relevant measures for the reasonable and optimized utilization of adhesion are ***–When the third-body medium exists on the rail surface,the train should adopt the low-level service braking to avoid the braking skidding by extending the braking *** with the current adhesion control strategy of small creepage,adopting appropriate strategies to control the train’s adhesion coefficient near the second peak point of the adhesion coefficient-slip ratio curve in large slip can effectively improve the traction/braking adhesion redundancy and the upper limit of adhesion utilization,thereby ensuring the traction/braking performance and operation safety of the ***/value–Most existing studies focus on the wheel-rail adhesion coefficient values and variation patterns under different medium conditions,without considering wheth

关键词： Wheel-rail adhesion redundancy PLS-160 wheel-rail adhesion simulation test rig Normal distribution Utilized adhesion coefficient

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Metabarcoding of fecal DNA reveals the broad and flexible diet of a globally endangered bird

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Current Zoology 2023年第5期69卷 501-513页

作者： Keyi Tang Yufeng Wang mengling wu Shufang Wang Changkun Fu Zhengwang Zhang Yiqiang Fu College of Life Sciences Sichuan Normal UniversityChengdu 610066China Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering College of Life SciencesBeijing Normal University Beijing 100875China

Knowing the diet of endangered wild animals is a prerequisite for species-specific conservation and habitat *** Sichuan partridge Arborophila rufipectus is a globally endangered Galliformes species endemic to the mountains of southwest *** information on the diet of this species is biased and fragmented owing to traditional observation *** is known about their dietary composition or how they respond to temporal variations in food resources throughout the *** this study,a dietary analysis was performed on 6o fecal samples using DNA Metabarcoding of invertebrates and plants to determine the primary animal and plant components of the diet across 3 critical periods of adult life history(breeding,postbreeding wandering,and overwintering).Preys from the dipteran order,followed by the lepidopteran and ara-neaen spp.,were the predominant,animal-derived ***,Rubus,Celastrus,Holboellia,and Actinidia *** a large abundance of fruits and seeds for this omnivorous *** temporal dietary changes among the 3 periods and a general shift toward lower dietary diversity during the breeding season were observed,suggesting that the Sichuan partridge can adjust their diet according to the availability of food resources and their own *** the composition and seasonal changes in Sichuan partridge diets informs the habitat management of native flora(the plant taxa that can generate berries and seeds,such as Symplocos,Rubus,Celastrus,and Holboellia,which are likely of conservation interest)to achieve full life-cycle conservation.

关键词： Arborophila rufipectus dietary composition endemic endangered species molecular diet analysis seasonal dietary variation Sichuan partridge

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Anisotropic NdFeB/SmCoCuFeZr composite bonded magnet prepared by warm compaction process

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Journal of Rare Earths 2017年第12期35卷 1221-1225页

作者： mengling wu Yuping Li Xin Wang Lizhao Chen Yaozhao Mu School of Materials Science and Engineering Nanjing Institute of Technology Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology Xi'an University

Anisotropic NdFeB/SmCoCuFeZr composite bonded magnets were prepared by warm compaction process. The effects of adding SmCoCuFeZr magnetic powder on the properties of anisotropic bonded NdFeB magnet were investigated in this work. The results show that, both magnetic properties and temperature stability of the bonded magnet can be improved by adding fine SmCoCuFeZr magnetic powder. In the present study, the optimal content of SmCoCuFeZr magnetic powder was about 20 wt.%, in this case, the Br, Hcj, and（BH）maxof the NdFeB/SmCoCuFeZr composite magnet achieved 0.943 T, 1250 kA/m, and168 kJ/m^3, respectively.

关键词： Composite magnet Anisotropic bonded NdFeB magnet Warm compaction process Rare earth permanent magnet Magnetic field

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An intelligent method for controlling the ECP braking system of a heavy-haul train

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Transportation Safety and Environment 2020年第2期2卷 133-147页

作者： Chun Tian mengling wu Lu Zhu Jun Qian Institute of Rail Transit Tongji University United Automotive Electronic Systems Co. Ltd.

An intelligent control method is proposed for the electronically controlled pneumatic(ECP)braking system of a heavy-haul train. The gradient of the ramp is estimated using a Kalman filter in real time and the braking force is adjusted by the backstepping method, so that vehicles on different gradients change their brake pressure with the change in the gradient to keep the instantaneous deceleration of each vehicle consistent, thus reducing the longitudinal impact between vehicles. The longitudinal impact of heavy-haul trains with and without intelligent control under different gradients, initial braking speeds, loads and complex terrains are simulated and analysed. The results show that when the intelligent control is applied, each vehicle can adjust its brake pressure in time according to the change of gradient. The intelligent control method can effectively alleviate the longitudinal impact of vehicles, and the reduction rate remains greater than 40% under the influence of various factors.

关键词： electronically controlled pneumatic braking system heavy-haul train Kalman filter longitudinal impact

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Rail temperature rise characteristics caused by linear eddy current brake of high-speed train

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Journal of Traffic and Transportation Engineering(English Edition) 2014年第6期1卷 448-456页

作者： Xiaoshan Lu Yunfeng Li mengling wu Jianyong Zuo Wei Hu Institute of Railway Transit Tongji University CSR Qingdao Sifang Locomotive Co. Ltd. Ecole Nationale Superieure d'Arts et Metiers AngersPays de la LoireFrance

The rail temperature rises when the linear eddy current brake of high-speed train is working, which may lead to a change of rail physical characteristics or an effect on train operations. Therefore, a study concerning the characteristics of rail temperature rise caused by eddy current has its practical necessity. In the research, the working principle of a linear eddy current brake is introduced and its FEA model is established. According to the generation mechanism of eddy current, the theoretical formula of the internal energy which is produced by the eddy current is deduced and the thermal load on the rail is obtained. ANSYS is used to simulate the rail temperature changes under different conditions of thermal loads. The research result shows the main factors which contribute to the rising of rail temperature are the train speed, brake gap and exciting current. The rail temperature rises non-linearly with the in- crease of train speed. The rail temperature rise curve is more sensitive to the exciting current than the air gap. Moreover, the difference stimulated by temperature rising between rails of 60 kg/m and 75 kg/m is presented as well.

关键词： high-speed train linear eddy current brake thermal load rail temperature rise

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Enterprise employees voluntarily delay retirement policy research

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International English Education Research 2015年第6期 119-121页

作者： mengling wu Management College Shanghai University Of Engineering Science China

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Ballistic performances of the hourglass lattice sandwich structures under high-velocity fragments

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Defence Technology（防务技术） 2024年第1期31卷 312-325页

作者： He-xiang wu Jia Qu Lin-zhi wu Key Laboratory of Advanced Ship Materials and Mechanics College of Aerospace and Civil EngineeringHarbin Engineering UniversityHarbin150001China School of Civil Engineering Northeast Forestry UniversityHarbin150040China

In this paper,the numerical simulation method is used to study the ballistic performances of hourglass lattice sandwich structures with the same mass under the vertical incidence of *** is paid to elucidating the influences of rod cross-section dimensions,structure height,structure layer,and rod inclination angle on the deformation mode,ballistic performances,and ability to change the ballistic direction of *** results show that the ballistic performances of hourglass lattice sandwich structures are mainly affected by their structural *** this respect,structural parameters optimization of the hourglass lattice sandwich structures enable one to effectively improve their ballistic limit velocity and,consequently,ballistic performances.

关键词： Hourglass lattice sandwich structures Ballistic performances high-velocity Finite element analysis

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Resilience-incorporated seismic risk assessment of precast concrete frames with“dry”connections

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Earthquake Engineering and Engineering Vibration 2024年第2期23卷 403-425页

作者： wu Chenhao Tang Yuchuan Cao Xuyang wu Gang Key Laboratory of Concrete and Prestressed Concrete Structures of the Ministry of Education Nanjing 211102China Department of Civil and Environmental Engineering University of CaliforniaLos AngelesCA 90095USA School of Civil Engineering Southeast UniversityNanjing 211102China College of Civil and Transportation Engineering Hohai UniversityNanjing 210024China

A resilience-incorporated risk assessment framework is proposed and demonstrated in this study to manifest the advantageous seismic resilience of precast concrete frame(PCF)structures with“dry”connections in terms of their low damage and rapid *** framework integrates various uncertainties in the seismic hazard,fragility,capacity,demand,loss functions,and post-earthquake *** this study,the PCF structures are distinguished from ordinary reinforced concrete frame(RCF)structures by characterizing multiple limit states for the PCF based on its unique damage ***,probabilistic story-wise pushover analyses are performed to yield story-wise capacities for the predefined limit *** the seismic resilience analysis,a step-wise recovery model is proposed to idealize the functionality recovery process,with separate considerations of the repair and non-repair *** recovery model leverages the economic loss and downtime to delineate the stochastic post-earthquake recovery curves for the resilience loss *** such,contingencies in the probabilistic post-earthquake repairs are incorporated and the empirical judgments on the recovery parameters are largely *** proposed framework is demonstrated through a comparative study between two“dry”connected PCFs and one RCF designed as alternative structural systems for a prototype *** results from the risk quantification indicate that the PCFs show reduced loss hazards and lower expected losses relative to the ***,the PCF equipped with energy dissipation devices at the“dry”connections largely reduces the expected economic loss,downtime,and resilience loss by 29%,56%,and 60%,respectively,compared to the RCF.

关键词： precast concrete frame non-emulative precast system seismic resilience seismic risk functional recovery

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重载列车电控空气制动系统纵向冲动影响分析

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同济大学学报（自然科学版） 2018年第7期46卷 964-971页

作者：吴萌岭祝露田春同济大学铁道与城市轨道交通研究院上海201804

应用电控空气(ECP)制动系统与纵向动力学联合仿真系统研究制动初速度、车钩间隙以及坡道坡度等对列车纵向冲动的影响规律,并分析纵向冲动与车辆速度差之间的内在联系.结果表明:制动初速度对列车纵向冲动无明显影响,而坡道坡度影响最显著... 详细信息

应用电控空气(ECP)制动系统与纵向动力学联合仿真系统研究制动初速度、车钩间隙以及坡道坡度等对列车纵向冲动的影响规律,并分析纵向冲动与车辆速度差之间的内在联系.结果表明:制动初速度对列车纵向冲动无明显影响,而坡道坡度影响最显著,其次是车钩间隙;列车最危险的制动位置是列车前3/8处于坡道上、其余在平直道上,并且该制动位置不随制动初速度、坡道坡度以及车钩间隙的变化而变化;当压(拉)钩力超过2 000kN时,最大压(拉)钩力与该车钩所对应的最小(大)速度差呈线性相关;一阶滤波后的速度差控制在-0.25~0.25 m·s^(-1)时最大压(拉)钩力大于2 000kN的概率不足5%.

关键词：重载列车电控空气制动系统纵向动力学车钩力坡道坡度

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New findings on the influence of El Nino events on tropical cyclone formation

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Science China Earth Sciences 2024年第3期67卷 892-893页

作者： Liguang wu Department of Atmospheric and Oceanic Sciences Institute of Atmospheric SciencesFudan UniversityShanghai 200438China

Tropical cyclones typically form over warm tropical and subtropical ocean surfaces, as their formation and intensification rely primarily on the energy provided by the ocean. Pioneering research by Gray (1968) revealed that the formation of tropical cyclones requires the sea surface temperature (SST) to be no less than 26.5℃. Consequently, SST is commonly recognized as a crucial parameter among the environmental factors influencing tropical cyclone formation(Gray, 1979;Emanuel and Nolan, 2004).

关键词： tropical cyclone ocean

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