检索结果-南通市图书馆

Ride-hailing origin-destination demand prediction with spatiotemporal information fusion

在线全文

学校读者我要写书评

暂无评论

Transportation safety and Environment 2024年第2期6卷 63-74页

作者： Ning Wang Liang Zheng Huitao Shen Shukai Li School of traffic and Transportation Engineering Central South UniversityChangsha 410075China state key laboratory of rail traffic control and safety Beijing Jiaotong UniversityBeijing 100044China

Accurate demand forecasting for online ride-hailing contributes to balancing traffic supply and demand,and improving the service level of ride-hailing platforms.In contrast to previous studies,which have primarily focused on the inflow or outflow demands of each zone,this study proposes a conditional generative adversarial network with a Wasserstein divergence objective(CWGAN-div)to predict ride-hailing origin-destination(OD)demand matrices.Residual blocks and refined loss functions help to enhance the stability of model training.Interpretable conditional information is employed to capture external spatiotemporal dependencies and guide the model towards generating more precise results.Empirical analysis using ride-hailing data from Manhattan,New York City,demon-strates that our proposed CWGAN-div model can effectively predict the network-wide OD matrix and exhibits strong convergence performance.Comparative experiments also show that the CWGAN-div outperforms other benchmarking methods.Consequently,the proposed model displays potential for network-wide ride-hailing OD demand prediction.

关键词： intelligent transport system ride-hailing generative adversarial networks spatiotemporal dependencies origin-destination(OD)demand prediction

Solving the constrained shortest path problem using random search strategy

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2010年第12期53卷 3258-3263页

作者： LI KePing, GAO ZiYou , TANG Tao & YANG LiXing state key laboratory of rail traffic control and safety, Beijing Jiaotong University, Beijing 100044, China state key laboratory of rail traffic control and safety Beijing Jiaotong University Beijing China

In this paper, we propose an improved walk search strategy to solve the constrained shortest path problem. The proposed search strategy is a local search algorithm which explores a network by walker navigating through the network. In order to analyze and evaluate the proposed search strategy, we present the results of three computational studies in which the proposed search algorithm is tested. Moreover, we compare the proposed algorithm with the ant colony algorithm and k shortest paths algorithm. The analysis and comparison results demonstrate that the proposed algorithm is an effective tool for solving the constrained shortest path problem. It can not only be used to solve the optimization problem on a larger network, but also is superior to the ant colony algorithm in terms of the solution time and optimal paths.

关键词： constrained shortest path deterministic random walk optimization

On the Polygonal Wear Evolution of Heavy-Haul Locomotive Wheels due to Wheel/rail Flexibility and Its Mitigation Measures

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2024年第1期37卷 40-61页

作者： Yunfan Yang Feifan Chai Pengfei Liu Liang Ling Kaiyun Wang Wanming Zhai state key laboratory of Mechanical Behavior and System safety of traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China state key laboratory of rail Transit Vehicle System Southwest Jiaotong UniversityChengdu 610031China

Wheel polygonal wear can immensely worsen wheel/rail interactions and vibration performances of the train and track,and ultimately,lead to the shortening of service life of railway components.At present,wheel/rail medium-or high-frequency frictional interactions are perceived as an essential reason of the high-order polygonal wear of railway wheels,which are potentially resulted by the flexible deformations of the train/track system or other external excitations.In this work,the effect of wheel/rail flexibility on polygonal wear evolution of heavy-haul locomotive wheels is explored with aid of the long-term wheel polygonal wear evolution simulations,in which different flexible modeling of the heavy-haul wheel/rail coupled system is implemented.Further,the mitigation measures for the polygonal wear of heavy-haul locomotive wheels are discussed.The results point out that the evolution of polygonal wear of heavy-haul locomotive wheels can be veritably simulated with consideration of the flexible effect of both wheelset and rails.Execution of mixed-line operation of heavy-haul trains and application of multicut wheel re-profiling can effectively reduce the development of wheel polygonal wear.This research can provide a deep-going understanding of polygonal wear evolution mechanism of heavy-haul locomotive wheels and its mitigation measures.

关键词： Heavy-haul locomotive Wheel polygonal wear Wheel/rail flexibility Long-term polygonal wear evolution Mitigation measures

Urban expressway traffic state forecasting based on multimode maximum entropy model

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2010年第10期53卷 2808-2816页

作者： SUN XiaoLiang1,2, JIA LiMin1, DONG HongHui1, QIN Yong1 & GUO Min3 1state key laboratory of rail traffic control and safety, Beijing Jiaotong University, Beijing 100044, China 2School of traffic and Transportation, Beijing Jiaotong University, Beijing 100044, China 3Beijing traffic Management Bureau, Beijing 100044, China state key laboratory of rail traffic control and safety Beijing Jiaotong University Beijing China School of traffic and Transportation Beijing Jiaotong University Beijing China Beijing traffic Management Bureau Beijing China

The accurate and timely traffic state prediction has become increasingly important for the traffic participants,especially for the traffic managements. In this paper,the traffic state is described by Micro-LOS,and a direct prediction method is introduced. The development of the proposed method is based on Maximum Entropy (ME) models trained for multiple modes. In the Multimode Maximum Entropy (MME) framework,the different features like temporal and spatial features of traffic systems,regional traffic state are integrated simultaneously,and the different state behaviors based on 14 traffic modes defined by average speed according to the date-time division are also dealt with. The experiments based on the real data in Beijing expressway prove that the MME models outperforms the already existing model in both effectiveness and robustness.

关键词： traffic state forecast maximum entropy model multimode

Energy-Efficient Driving Strategy for High-Speed Trains with Considering the Checkpoints

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2024年第3期33卷 847-858页

作者： Zixuan ZHANG Yuan CAO Shuai SU state key laboratory of rail traffic control and safety Beijing Jiaotong University School of Electronic and Information Engineering Beijing Jiaotong University National Engineering Research Center of rail Transportation Operation and control System Beijing Jiaotong University Frontiers Science Center for Smart High-speed railway System Beijing Jiaotong University

With rising energy prices and concerns about environmental issues,energy-efficient driving strategies(EEDS) for high-speed trains have received a substantial amount of attention.In particular,energy-saving schemes play a huge role in reducing the energy and operating costs of trains.This article studies the EEDS of high-speed trains at a given time.A well-posed model is formulated,in which the constraints of the checkpoints,in addition to the speed limits,vehicle dynamics,and discrete control throttle,are first considered.For a given control sequence,the Karush-Kuhn-Tucker(KKT) conditions are used to obtain the necessary conditions for an EEDS.According to several key equations of the necessary conditions,the checkpoint constraints are satisfied.Some case studies are conducted based on the data of the Beijing-Shanghai high-speed line to illustrate the effectiveness of the proposed approach.

关键词： Energy consumption Costs Simulation Mathematical models Energy efficiency Vehicle dynamics Optimization

Performance analysis of uplink MIMO MC-CDMA systems based on linear zero-forcing V-BLAST algorithm

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science in China(Series F) 2008年第9期51卷 1305-1318页

作者： YANG Wei1,2 & YANG Wei1 1 state key laboratory of rail traffic control and safety,Beijing Jiaotong University,Beijing 100044,China 2 National Mobile Communications Research laboratory,Southeast University,Nanjing 210096,China state key laboratory of rail traffic control and safety Beijing Jiaotong University Beijing China National Mobile Communications Research laboratory Southeast University Nanjing China

A structure was proposed for multiple-input-multiple-output multicarrier code divi- sion multiple access （MIMO MC-CDMA） uplink transmission system. Linear zero- forcing V-BLAST （ZF V-BLAST） algorithm and maximum ratio combining （MRC） scheme was applied to the receivers. The average bit error rate （BER） expression was derived on condition that the number of receive antennas was larger than that of transmit antennas and it was verified by simulations. Numerical results show that the number of transmit and receive antennas, as well as the number of sub- carriers, all exert significant effects on the BER performance. The space diversity and frequency diversity show different abilities to improve the BER performance. The MIMO MC-CDMA system based on linear ZF V-BLAST algorithm is capable of achieving better BER performance than that of the conventional MC-CDMA system by reducing the number of transmit antennas or increasing the number of receive antennas.

关键词： bit error rate(BER) ,multiple-input-multiple-output(MIMO) ,multicarrier code division multiple access(MC-CDMA) ,zero-forcing(ZF)

Artificial Intelligence Based Multi-Scenario mmWave Channel Modeling for Intelligent High-Speed Train Communications

在线全文

学校读者我要写书评

暂无评论

China Communications 2024年第3期21卷 260-272页

作者： Zhang Mengjiao Liu Yu Huang Jie He Ruisi Zhang Jingfan Yu Chongyang Wang Chengxiang School of Microelectronics Shandong UniversityJinan 250101China the state key laboratory of rail traffic control and safety Beijing Jiaotong UniversityBeijing 100044China The National Mobile Communications Research laboratory School of Information Science and EngineeringSoutheast UniversityNanjing 210096China The Purple Mountain Laboratories Nanjing 211111China

A large amount of mobile data from growing high-speed train(HST)users makes intelligent HST communications enter the era of big data.The corresponding artificial intelligence(AI)based HST channel modeling becomes a trend.This paper provides AI based channel characteristic prediction and scenario classification model for millimeter wave(mmWave)HST communications.Firstly,the ray tracing method verified by measurement data is applied to reconstruct four representative HST scenarios.By setting the positions of transmitter(Tx),receiver(Rx),and other parameters,the multi-scenarios wireless channel big data is acquired.Then,based on the obtained channel database,radial basis function neural network(RBF-NN)and back propagation neural network(BP-NN)are trained for channel characteristic prediction and scenario classification.Finally,the channel characteristic prediction and scenario classification capabilities of the network are evaluated by calculating the root mean square error(RMSE).The results show that RBF-NN can generally achieve better performance than BP-NN,and is more applicable to prediction of HST scenarios.

关键词： artificial intelligence channel characteristic prediction HST channel millimeter wave scenario classification

The risk factors and threshold level of subchronic inhalation exposure of reclaimed water

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2024年第3期137卷 639-650页

作者： Jiayang Kong Yun Lu Yunru Ren Menghao Chen Gang Liu Liangliang Shi state key Joint laboratory of Environment Simulation and Pollution control State Environment Protection Key Laboratory of Microorganism Application and Risk ControlSchool of EnvironmentTsinghua UniversityBeijing 100084China

Inhalation of reclaimed water is known to cause lung infammation,and free endotoxins have been shown to be a major risk factor for acute exposure.Subchronic exposure has also been shown to induce infammatory responses with visible tissue damage.However,subchronic risk factors have yet to be identified,and a threshold for the protection of occupational populations during urban reuse is necessary.In this study,potential risk factors in reclaimed water were examined by subchronic exposure with fractionated reclaimed water,and the health risk threshold was tested with a series of diluted reclaimed water.Accordingly,following a 12-week exposure,macromolecules and microorganisms were found to be two major risk factors in reclaimed water that could cause pulmonary infammation,including increased proportion of polymorphonuclear leukocytes in bronchoalveolar fuid,formation of inducible bronchus-associated lymphoid tissue,and elevation of Immunoglobulin A levels.Moreover,infammation persisted after a 4-week recovery period.The calculated threshold of reclaimed water exposure for mice was 31.8 Endotoxin Unit(EU)/(kg·day)under when exposed to 50%additional relative humidity from reclaimed water at 25℃ for 2 hr/day.Meanwhile,the subchronic threshold estimate for humans under the same exposure conditions was found to be 12.2 EU/(kg·day),corresponding to endotoxin levels of 61.7 EU/mL in reclaimed water.The threshold level of endotoxin was lower than that in most non-potable reclaimed water.The findings of this study suggest that occupational exposure of reclaimed water can serve as a potential risk to workers.

关键词： Reclaimed water Inhalation exposure Risk factor Threshold Infammation Endotoxin

Influence of vibration on the lubrication effect of a splash-lubricated gearbox

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第4期25卷 324-339页

作者： Yi LIU Kailin ZHANG Shuai SHAO Hongxu XIANG Zhijian YE state key laboratory of rail Transit Vehicle System Southwest Jiaotong UniversityChengdu 610031China

In this study,we investigate the effect of rail vibrations on the lubrication and efficiency of a splash-lubricated gearbox;specifically,the gearbox of a rail-transit vehicle.A high-fidelity 3D numerical model of the gearbox in a moving reference system is described,as well as computational fluid dynamics(CFD)simulations of the gearbox with different vibration directions.The effects of rotational speed,oil-immersion depth,and different oil-injection volume rates on lubrication and efficiency are discussed.We propose a method of evaluating the internal lubrication condition of a splash-lubricated gearbox and quantitatively compare the effects of different operating parameters on lubrication and efficiency.Finally,our experiment to verify the feasibility of the simulation method is described.The results show that with vibration,the churning loss and oil supply for the bearings are significantly higher than those under static conditions.In addition,among different vibrational directions,lateral vibration has the greatest influence on the lubrication condition and efficiency of the gearbox.For the studied railway-vehicle gearbox,the best lubrication condition is achieved at a rotational speed of 1600 r/min and an oil-immersion depth of two times the tooth height(2.Oh).Rotational speed is the operating parameter that has the most significant effect on the lubrication and efficiencyofthegearbox.

关键词： Comprehensive lubrication evaluation Churning loss Moving reference system Splash lubrication Vibrational excitation Gearbox