Abstract:Based on the Optistruct software, the modal analysis, stochastic vibration analysis and local dynamic stiffness analysis of an EV battery pack are carried out by using the finite element method. The results show that the first order modal frequency is 15.7 Hz, slightly higher than the external excitation frequency, so the resonance can be avoided theoretically; the maximum stress of the lower cover of the battery pack exceeds the tensile limit stress of the material; the local dynamic stiffness of the battery pack meets the basic requirements, and there is a slight difference in the low frequency of 0 ～60 Hz slightly, the error caused by simulation when the battery pack is separated from the body as an independent body. The results of this study can provide reference for the design of power battery pack of the electric vehicle

Abstract:In order to reduce the occurrence rate of highway traffic accidents,the causation of three major traffic accidents on a highway in Guangdong Province and two major traffic accidents on a highway in Shandong Province are analyzed using the 24Model.The causation chain of traffic accidents is established from the perspectives of unsafe actions,physical and safety capabilities at the individual level,and the safety management system and safety culture at the organizational level.The results show that the direct causes of the accidents include failure to take necessary deceleration measures to control the speed,failure to maintain a reasonable distance from the preceding vehicle,failure to control vehicle speed due to long downhill sections,failure to handle overloaded vehicles in accordance with regulations,poor visibility during night driving,slippery roads in rainy weather,and lack of road-side guiding warning devices.The indirect causes of the accidents include a lack of safety knowledge and awareness among drivers and management personnel.The root causes of the accidents include ineffective enforcement of traffic safety regulations and the need for improvement in the"one road,three parties"system.The fundamental cause of the accidents is the lack of a perfect traffic safety culture.

Abstract:To reduce the probability of collisions between fishing vessels in the vicinity of the coast and ensure the safety of fishing vessel navigation,an analysis of the causes of these collisions is conducted using the fishbone fishbone diagram method from the perspective of fishing vessels.The causes of the accidents are used as nodes in a Bayesian network for inference and validation.Posterior probability inference and sensitivity analysis are employed to explore the causal chain of accidents.The results indicate that human factors have the greatest impact on collisions involving fishing vessels near the coast,followed by management factors.Among the human factors,high sensitivity is observed for failure to display proper lights and signals,failure to take effective evasive actions,negligence in lookout,and inadequate crew qualifications.These factors have a significant impact on collisions involving fishing vessels in the vicinity of the coast.

Abstract:In order to reduce the road traffic accident rate and minimize accident losses,the gray wolf optimizer(GWO)algorithm,which has strong global traversal and convergence properties,is used to optimize the initial learning rate,hidden layer nodes,regularization coefficient and other parameters in the long short term memory(LSTM)neural network.The GWO-LSTM road traffic accident prediction model is constructed.Taking the road traffic fatal accident data from 2000 to 2019 as the sample data,the traffic accident data is divided into monthly granularity,weekly granularity,and hourly granularity.The road traffic accident prediction results of the GWO-LSTM model,autoregressive moving average(ARMA)model,back propagation neural network(BPNN)model,and standard LSTM model are compared and analyzed.The results show that under the three time granularities,the GWO-LSTM model has the smallest average absolute percentage error and root mean square error,and high prediction accuracy.It can be used for road traffic accident prediction.

Abstract:In order to improve the transportation department management efficiency of dangerous goods road transportation enterprises , Ward′s and method , one of the clustering methods , is used to classify all the enterprises according to different security levels in one area .First, the safety assessment index system is determined from the longitudinal angel of “safety awareness and hardware management”.Then, based on the index system , the safety assessment of all the dangerous goods road transport enterprises in one area is performed by the method of system clustering analysis .Finally , the real situations are deeply analyzed combined with the accidents of these enterprises which happened in recent years .The results show that the clustering analysis method can accurately classify all the enterprises according to different security levels , which has the guide meaning for the management of transportation departments .

Abstract:In order to solve the problem of poor stability in the rotational speed of the track-based inspection robot in a substation,a permanent magnet synchronous motor(PMSM)with good control characteristics is used as the driving motor to design the driving system for the substation track-mounted inspection robot.The structural and motion parameters of the robot are calculated to complete the motor selection.By combining field-oriented control(FOC)and space vector pulse width modulation(SVPWM)strategies,a simulation model of the PMSM drive system is built using MATLAB Simulink software,employing a proportional-integral-derivative(PID)dual-loop control method for velocity and current.The stability and reliability of the designed system are verified,and a physical test platform is set up to conduct no-load and load speed tests on the motor.The results show that the PMSM drive system,using the PID dual-loop velocity-current control,achieves stable and reliable speed control for the substation track-mounted inspection robot.The experimental results are consistent with the simulation results,meeting the expected design requirements,and proving the feasibility of the proposed design solution.