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Mechanism of internal thermal runaway propagation in blade batteries

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Journal of Energy Chemistry 2024年第2期89卷 184-194,I0005页

作者： Xuning Feng Fangshu Zhang Wensheng Huang Yong Peng Chengshan Xu Minggao Ouyang School of vehicle and Mobility Tsinghua UniversityBeijing 100084China

Blade batteries are extensively used in electric vehicles,but unavoidable thermal runaway is an inherent threat to their safe *** study experimentally investigated the mechanism underlying thermal runaway propagation within a blade battery by using a nail to trigger thermal runaway and thermocouples to track its propagation inside a *** results showed that the internal thermal runaway could propagate for up to 272 s,which is comparable to that of a traditional battery *** velocity of the thermal runaway propagation fluctuated between 1 and 8 mm s^(-1),depending on both the electrolyte content and high-temperature gas *** the early stages of thermal runaway,the electrolyte participated in the reaction,which intensified the thermal runaway and accelerated its *** the battery temperature increased,the electrolyte evaporated,which attenuated the acceleration *** diffusion affected thermal runaway propagation through both heat transfer and mass *** experimental results indicated that gas diffusion accelerated the velocity of thermal runaway propagation by 36.84%.We used a 1D mathematical model and confirmed that convective heat transfer induced by gas diffusion increased the velocity of thermal runaway propagation by 5.46%-17.06%.Finally,the temperature rate curve was analyzed,and a three-stage mechanism for internal thermal runaway propagation was *** Stage I,convective heat transfer from electrolyte evaporation locally increased the temperature to 100℃.In Stage II,solid heat transfer locally increases the temperature to trigger thermal *** StageⅢ,thermal runaway sharply increases the local *** proposed mechanism sheds light on the internal thermal runaway propagation of blade batteries and offers valuable insights into safety considerations for future design.

关键词： Lithium-ion battery Blade battery Thermal runaway Internal thermal runaway propagation

A Survey on an Emerging safety Challenge for Autonomous vehicles:safety of the Intended Functionality

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Engineering 2024年第2期33卷 17-34页

作者： Hong Wang Wenbo Shao Chen Sun Kai Yang Dongpu Cao Jun Li Tsinghua Intelligent vehicle Design and safety Research Institute School of Vehicle and MobilityTsinghua UniversityBeijing 100084China CogDrive lab Department of Mechanical and Mechatronics EngineeringUniversity of WaterlooWaterlooON N2L3G1Canada College of Mechanical and vehicle Engineering Chongqing UniversityChongqing 400044China

As the complexity of autonomous vehicles(AVs)continues to increase and artificial intelligence algorithms are becoming increasingly ubiquitous,a novel safety concern known as the safety of the intended functionality(SOTIF)has emerged,presenting significant challenges to the widespread deployment of *** focuses on issues arising from the functional insufficiencies of the AVs’intended functionality or its implementation,apart from conventional safety *** the systems engineering standpoint,this study offers a comprehensive exploration of the SOTIF landscape by reviewing academic research,practical activities,challenges,and perspectives across the development,verification,validation,and operation *** research encompasses system-level SOTIF studies and algorithm-related SOTIF issues and ***,it encapsulates practical SOTIF activities undertaken by corporations,government entities,and academic institutions spanning international and Chinese contexts,focusing on the overarching methodologies and practices in different ***,the paper presents future challenges and outlook pertaining to the development,verification,validation,and operation phases,motivating stakeholders to address the remaining obstacles and challenges.

关键词： safety of the intended functionality Autonomous vehicles Artificial intelligence Uncertainty Verification Validation

Effects of nano-metal oxide additives on ignition and combustion properties of MICs-boron rich fuels

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DEFENCE TECHNOLOGY 2024年第9期39卷 157-167页

作者： Hu, Liang Liu, Danyang Yang, Kun Lu, Jianying Shi, Chao Wang, Jianyu Liu, Xinhang Chen, Lang Beijing Inst Technol State Key Lab Explos Sci & Safety Protect Beijing 100081 Peoples R China

Boron has been considered a promising powdered metal fuel for enhancing composite propellants' energy output due to its high energy density. However, the high ignition temperature and low combustion efficiency limit the application of boron powder due to the high boiling point of the boron oxide layer. Much research is ongoing to overcome these shortcomings, and one potential approach is to introduce a small quantity of metal oxide additives to promote the reaction of boron. This study prepared boron-rich fuels with 10 wt% of eight nano-metal oxide additives by mechanical ball milling. The effect of metal oxides on the thermo-oxidation, ignition, and combustion properties of boron powder was comprehensively studied by the thermogravimetric analysis (TG), the electrically heated filament setup (T-jump), and the laser-induced combustion experiments. TG experiments at 5 K/min found that Bi2O3, MoO3, TiO2, Fe2O3, and CuO can promote thermo-oxidation of boron. Compared to pure boron, T-onset can be reduced from 569 degrees C to a minimum of 449 degrees C (B/Bi2O3). Infrared temperature measurement in T-jump tests showed that when heated by an electric heating wire at rates from 1000 K/s to 25000 K/s, the ignition temperatures of B/Bi2O3 are the lowest, even lower than the melting point of boron oxide. Ignition images and SEM for the products further showed that the high heating rate is beneficial to the rapid reaction of boron powder in the single-particle combustion state. Fuels (B/Bi2O3, B/MoO3, and B/CuO) were mixed with the oxidant AP and ignited by laser to study the combustion performance. The results showed that B/CuO/AP has the largest flame area, the highest BO2 characteristic spectral intensity, and the largest burn rate for powder lines. To combine the advantages of CuO and Bi2O3, binary metal oxide (CBO, mass ratio of 3:1) was prepared and the test results showed that CBO can very well improve both ignition and combustion properties of boron. Especially B/CBO

关键词： Boron-rich fuel Mechanical ball milling electrically heated filament Laser-induced combustion PARTICLES MODEL

Efficiency-oriented vehicle relocation of shared autonomous electric fleet in station-based car-sharing system

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第4期11卷 681-699页

作者： Ning Wang Hangqi Tian Jiahui Guo Huahua Wu Jian Lyu School of Automotive Studies Tongji UniversityShanghai 201804China State Grid Zhejiang electric Power Co. Ltd.Hangzhou 310007China State Grid Zhejiang electric vehicle Service Co. Ltd.Hangzhou 310012China

Long waiting delays for users and significant imbalances in vehicle distribution are bothering traditional station-based one-way electric car-sharing system *** address the problems above,a“demand forecast-station status judgement-vehicle relocation”multistage dynamic relocation algorithm based on the automatic formation cruising technology was proposed in this *** stage one,a novel trip demand forecast model based on the long short-term memory network was established to predict users'car-pickup and car-return order volumes at each *** stage two,a dynamic threshold interval was determined by combining the forecast results with the actual vehicle distribution among stations to evaluate the status of each *** vehicle-surplus,vehicleinsufficient,vehicle-normal stations,and the number of surplus or insufficient vehicles for each station were *** stage three,setting driving mileage and carbon emission as the optimization objectives,an integer linear programming mathematical model was constructed and the optimal vehicle relocation scheme was obtained by the commercial solver *** 43 stations and 187 vehicles in Jiading District,Shanghai,China,as a case study,results showed that rapid vehicle rebalancing among stations with minimum carbon emissions could be realized within 15 min and the users’car-pickup and car-return demands could be fully satisfied without any refusal.

关键词： Sustainable transportation One-way car-sharing Shared autonomous electric fleet Multistage dynamic relocation algorithm

Numerical and Experimental Analysis of the Aerodynamic Torque for Axle-Mounted Train Brake Discs

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Fluid Dynamics & Materials Processing 2024年第8期20卷 1867-1882页

作者： Nan Liu Chen Hong Xinchao Su Xing Jin Chen Jiang Yuqi Shi Bingkun Wang Brake System laboratory CRCC(Qingdao)Vehicle Inspection Station Co.Ltd.Qingdao266031China Brake System laboratory CRRC Qingdao Sifang Rolling Stock Research Institute Co.Ltd.Qingdao266031China The State Key laboratory of Heavy-Duty and Express High-Power electric Locomotive Central South UniversityChangsha410075China Key laboratory of Traffic safety on Track of Ministry of Education School of Traffic&Transportation EngineeringCentral South UniversityChangsha410075China National&Local Joint Engineering Research Center of safety Technology for Rail vehicle Changsha410075China

As the velocity of a train increases,the corresponding air pumping power consumption of the brake discs increases *** the present experimental study,a standard axle-mounted brake disc with circumferential pillars was analyzed using a 1:1 scale model and a test rig in a wind *** particular,three upstream velocities were selected on the basis of earlier investigations of trains operating at 160,250,and 400 km/h,***,3D steady computational fluid dynamics(CFD)simulations of the flow field were conducted to compare with the wind tunnel test *** results for a 3-car train at 180 km/h demonstrated:(1)good agreement between the air resistance torques obtained from the wind tunnel tests and the related numerical results,with differences ranging from 0.95%to 5.88%;(2)discrepancies ranging from 3.2 to 3.8 N·m;(3)cooling ribs contributing more than 60%of the air resistance torque;(4)the fast rotation of brake discs causing a significantly different flow field near the bogie area,resulting in 25 times more air pumping power loss than that obtained in the stationary brake-disc case.

关键词： Axle-mounted train brake disc aerodynamic torque wind tunnel test numerical simulation

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

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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 *** effects of rotational speed,oil-immersion depth,and different oil-injection volume rates on lubrication and efficiency are *** 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 ***,our experiment to verify the feasibility of the simulation method is *** results show that with vibration,the churning loss and oil supply for the bearings are significantly higher than those under static *** addition,among different vibrational directions,lateral vibration has the greatest influence on the lubrication condition and efficiency of the *** 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(***).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

Machine learning and neural network supported state of health simulation and forecasting model for lithium-ion battery

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Frontiers in Energy 2024年第2期18卷 223-240页

作者： Nan QI Kang YAN Yajuan YU Rui LI Rong HUANG Lai CHEN Yuefeng SU Beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China Department of Energy and Environmental Materials School of Materials Science and EngineeringBeijing Institute of TechnologyBeijing 100081China Beijing electric vehicle Co. Ltd.Beijing 100176China

As the intersection of disciplines deepens,the field of battery modeling is increasingly employing various artificial intelligence(AI)approaches to improve the efficiency of battery management and enhance the stability and reliability of battery *** paper reviews the value of AI methods in lithium-ion battery health management and in particular analyses the application of machine learning(ML),one of the many branches of AI,to lithium-ion battery state of health(SOH),focusing on the advantages and strengths of neural network(NN)methods in ML for lithium-ion battery SOH simulation and *** is one of the important branches of ML,in which the application of NNs such as backpropagation NN,convolutional NN,and long short-term memory NN in SOH estimation of lithium-ion batteries has received wide *** so far have shown that the utilization of NN to model the SOH of lithium-ion batteries has the advantages of high efficiency,low energy consumption,high robustness,and scalable *** the future,NN can make a greater contribution to lithium-ion battery management by,first,utilizing more field data to play a more practical role in health feature screening and model building,and second,by enhancing the intelligent screening and combination of battery parameters to characterize the actual lithium-ion battery SOH to a greater *** in-depth application of NN in lithium-ion battery SOH will certainly further enhance the science,reliability,stability,and robustness of lithium-ion battery management.

关键词： machine learning lithium-ion battery state of health neural network artificial intelligence

Integrated Active Suspension and Anti-Lock Braking Control for Four-Wheel-Independent-Drive electric vehicles

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Chinese Journal of Mechanical Engineering 2024年第1期37卷 87-98页

作者： Ze Zhao Lei Zhang Xiaoling Ding Zhiqiang Zhang Shaohua Li Liang Gu National Engineering Research Center for electric vehicles Beijing Institute of TechnologyBeijing 100081China State Key laboratory of Mechanical Behavior and System safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China

This paper presents an integrated control scheme for enhancing the ride comfort and handling performance of a four-wheel-independent-drive electric vehicle through the coordination of active suspension system(ASS)and anti-lock braking system(ABS).First,a longitudinal-vertical coupled vehicle dynamics model is established by integrating a road input *** the coupling mechanisms between longitudinal and vertical vehicle dynamics are *** ASS-ABS integrated control system is proposed,utilizing an H∞controller for ASS to optimize load transfer effect and a neural network sliding mode control for ABS ***,the effectiveness of the proposed control scheme is evaluated through comprehensive tests conducted on a hardware-in-loop(HIL)test *** HIL test results demonstrate that the proposed control scheme can significantly improve the braking performance and ride comfort compared to conventional ABS control methods.

关键词： Four-wheel-independent-drive electric vehicles Active suspension system(ASS) Anti-lock braking system(ABS) Vertical-longitudinal vehicle dynamics

A novel multi-state bogie system reliability evaluation approach by extended d-MC model for high-speed trains

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Transportation safety and Environment 2024年第3期6卷 35-46页

作者： Yong Fu Ruoqu Liu Jisheng Dai Wenlong Zhu Xin Liu Yong Qin Zhuzhou CRRC Times electric Co. Ltd.Times RoadShifeng DistrictZhuzhouHunan 412001China Department of Statistics University of WarwickCoventry CV47ALUnited Kingdom State Key lab of Rail Traffic Control&safety Beijing Jiaotong UniversityHaidian DistrictBeijing 100044China

Bogie is a pivotal system and plays a critical part in the safety and reliability management of high-speed ***,the available bogie system reliability analysis methods lack the consideration of multi-state characteristics,and the common multi-state reliability analysis methods,being an NP-hard problem,lead to low *** order to overcome these drawbacks,this paper proposes a novel multi-state rail train bogie system reliability analysis approach based on the extended d-MC *** different function interactions within the bogie system are considered to build the multi-state bogie system flow network ***,an extended d-MC model is established to remove unnecessary d-MC candidates and duplicates,which greatly enhances the computing *** bogie system reliability is calculated,and examples are *** experiments are carried out for the different operational conditions of the bogie system and are used to test the practicability of the method proposed in this article;it is found that this method outperforms a newly developed method in solving multi-state reliability problems.

关键词： multi-state system reliability bogie flow network extended d-MC model