Abstract:To meet the requirements of continuous and high-speed data acquisition of passenger body pressure under instantaneous and high-impact conditions in automotive collision sled tests， a high speed passenger body pressure collection system was designed based on STM32H723ZGT6 high-performance MCU and array pressure sensor， where the design scheme included high-performance hardware， local data acquisition， local storage， and post-experiment uploading. By applying high-performance microcontroller units and memory expansion， the real-time performance and stability of data collection have been improved. The data acquisition frequency for 4 576 force-sensitive points on both the seat cushion and backrest could reach 200 Hz， satisfying the data acquisition requirements for sled tests while also controlling system costs. Additionally， a passenger body pressure data analysis method based on single-channel image feature extraction was introduced. In rigid seat sled tests， data on passenger body pressure were collected from a volunteer under four different seat conditions. The passenger’s pelvic displacement trajectory， maximum average rectangular window pressure， voltage variation trend， and weight change trends for the entire seat cushion and its three sub-regions were obtained and visualized. The obtained data characteristics are essentially consistent with the passenger posture responses obtained by the high-speed camera.

Abstract:To reduce the commonly high Neck Injury Criterion （NIC） and upper neck extension moment in the assessment of whip test injuries， based on the LS-DYNA finite element model and physical test results of a certain car seat， the basic structure and dynamic response under rear collision were first analyzed. A multi-rigid body dynamic analysis model for the seat whiplash test was established using the Mathematical Dynamic Model （MADYMO） software. Then， through the analysis of injury mechanisms and sensitivity analysis of the main design parameters of the seat， the main geometric structural parameters in the seat structure were determined， and a numerical model was established based on this. Finally， using multi-objective optimization algorithms， a corresponding optimization plan for seat whiplash resistance performance was obtained. The results showed that by adjusting the position of the seat frame crossbeam and headrest， the consistency of the passenger’s head and lower neck movement was improved， reducing the NIC by 58.5%， and the upper neck extension moment met the highest performance limit.

Abstract:This study aims to identify the influence of bicycle types and riding postures on the lower extremity kinematics and injury of cyclists during vehicle-bicycle collisions. For this purpose， the finite element models of two typical bicycles （shared bicycle and mountain bike） were established. Three types of riding postures （Struck foot front， up， and down） and a collision speed of 40 km/h as well as a riding speed of 10 km/h were adopted to conduct the current study. At last， the kinematic response and injury condition were analyzed through a matrix of 6 simulation tests using different bicycle types and riding postures. The results showed that compared with the shared bicycle， the bicyclist riding the mountain bike with a high cross-bar frame structure suffered a high tibia fracture risk. The high cross-bar frame structure of the mountain bike limited the movement of the lower leg during the collision. The kinematic response of the knee joint and ligament injury was affected as a result. The current study also determined that bicyclists with struck foot down riding posture were prone to sustain severe lower extremity injuries. In this position， the tibia is subjected to a large bending moment of 257.5 N·m. The medial collateral ligament has an elongation value of 19.3 mm. Therefore， the kinematic response of the cyclist’s lower leg extremity varies with the types of bicycle， whereas the lower extremity injuries change with the riding postures.

Abstract:To investigate the driver dynamic response in the process of autonomous emergency steering， the integration of active safety control technologies and passive safety protection strategies was used to carry out the integrated simulation of driver out-of-position response in the special autonomous emergency steering scenarios. Firstly， the automatic emergency steering control model was established based on the model predictive control algorithm. Co-simulation was completed with PreScan， CarSim， and Simulink software to obtain the vehical’s dynamic response during the steering process. Then， combined with the active human model and the driver side restraint system model， the motion characteristics of the vehicle and the driver and the improvement effect of the active control retractor seatbelt on the driver’s out-of-position were analyzed. Studies show that the dynamic response of the vehicle and the driver is divided into two phases： right-leaning and left-leaning during the process of the autonomous emergency steering with the longitudinal lane change distance of 40 m， 50 m， and 60 m under the driving speed of 72 km/h. The lateral acceleration and roll angle of the vehicle and the maximum out-of-position of the active human model in the right-leaning phase are significantly higher than those in the left-leaning phase. The maximum lateral out-of-position of the driver’s head decreases from 89.56 mm to 70.22 mm and 53.05 mm with the increase of longitudinal lane change distance. The active control retractor seatbelt effectively improved the out-of-position of the driver and the driver’s safety in the autonomous emergency steering process. The maximum lateral out-of-position of the head was reduced by 18.90%， 49.56%， and 67.62%， respectively， and the maximum lateral out-of-position of the chest was decreased by 12.70%， 41.63%， and 53.69%， respectively.

Abstract:To characterize representative characteristic pulse under a collision test condition and clarify corresponding occupant injury response characteristics， a feasible method of characteristic pulse processing based on pulse data from four vehicle types under 50% frontal overlap with the Mobile Progressive Deformable Barrier （MPDB） test condition was proposed. Firstly， the distribution regularity of characteristic parameters of four vehicle types was summarized and analyzed. Samples were then subjected to time normalization and acceleration feature averaging processing， followed by time scaling to maintain pulse shape characteristics and continuity， resulting in the characteristic pulse of the MPDB test condition. Subsequently， based on the principle of momentum conservation， the characteristic pulse was equivalent to a double trapezoidal wave to meet the application stability requirements of sled testing and simulation. Finally， through the simulation of occupant motion response and injury using the MPDB characteristic pulse and equivalent double trapezoidal wave， a minimum difference of 1% in occupant injury parameters was observed. The results indicate that time and intensity obtained by the normalized feature averaging method can conform to the characteristic parameters of the pulse samples， and the equivalent double trapezoidal wave can effectively capture occupant motion injury response under the characteristic pulse.

Abstract:Research on assisted driving functions of lane-change decision-making and trajectory tracking control considering driver dissatisfaction is carried out for autonomous lane-change scenarios on highways. First， the psychological factors of drivers were taken into account in lane-change decision-making， and a lane-change decision-making model based on driver dissatisfaction and minimum safe distance was established. Then， a lateral Linear Quadratic Regulator （LQR） controller was established based on the tracking error model to obtain the optimal feedback front wheel steering angle. Due to the problem that the weight matrices Q and R needed to be debugged repeatedly， a lateral LQR controller based on the Genetic Algorithm （GA） was proposed to obtain the optimal weight matrices Q and R， which in turn improves the robustness of the algorithm. The longitudinal LQR controller was also established to maintain the desired vehicle speed. Autonomous lane-change technology was validated using PreScan，MATLAB/Simulink and CarSim simulation platforms， and the robustness and reliability of the lateral LQR controller were verified under different fixed-speed lane-changing conditions. Under the condition of unsatisfied lane-change safety， the variable desired speed could be followed stably by the longitudinal LQR controller with a absolute value of maximum speed error of 0.69 km/h. Further comparing the lateral control performances of the LQR controller and GA+LQR controller， the lateral and heading tracking accuracies were improved by 66.7% and 27%， respectively， using the GA+LQR controller. The results confirm that the longitudinal LQR controller and the optimized GA+LQR controller have good tracking accuracies under different lane-change conditions.

Abstract:To facilitate the rapid calculation of fatigue damage and accurate assessment of the remaining life of the integrated transmission system， a real-time evaluation model for the running load of the transmission main shaft under multiple operating conditions is proposed. The model first extracted characteristic parameters of typical operating conditions for special vehicles and realizeed real-time discrimination of these conditions using K-means clustering and support vector machine methods. Then， a transmission main shaft load evaluation model based on convolutional neural networks-long short-term memory was constructed. Bayesian algorithm was employed to optimize hyperparameters， such as learning rate and network depth， aiming to improve the accuracy of the transmission main shaft load evaluation. Finally， the model was validated through experimental data collected under typical operating conditions of special vehicles. The results show that under shifting， steering， and climbing conditions， the average relative errors of the model’s load evaluation for the transmission main shaft are 0.150， 0.014， 0.006 （5-degree slope）， and 0.004 （10-degree slope）， respectively， indicating the effectiveness of the model in assessing the load of the integrated transmission system under variable operating conditions.

Abstract:Aiming at the turbulence effect of hydrogen gas foil bearings in practical engineering applications， the static and dynamic performances of the gas foil bearings， lubricated by low-temperature hydrogen， are obtained by coupling the Link-Spring model and Reynolds equation， where the Reynolds equation is modified by the law of the wall， combined with deep hypothermia state of hydrogen gas foil bearings. The static performances of the gas foil bearing lubricated by low-temperature hydrogen and other gas media are compared. The effects of eccentricity， ambient pressure， width-diameter ratio， and nominal clearance on the static and dynamic performances of the gas foil bearing are analyzed. The results showed that the load capacity of gas foil bearing in low-temperature and high-pressure hydrogen conditions is relatively low compared with that of atmospheric air and low-temperature and high-pressure nitrogen lubricating conditions. The load capacity can be intensified by increasing the eccentricity， ambient pressure， width-diameter ratio， the dynamic viscosity coefficients， and reducing the nominal clearance. The direct dynamic stiffness coefficients show an upward trend with the increasing ambient pressure and the decreasing nominal clearance.

Abstract:For thrust gas foil bearings integrating Supercritical Carbon Dioxide （S-CO2） as the working medium， a Back Propagation （BP） neural network algorithm is employed to propose a physical property model for S-CO2. To account for the non-idea gas behavior in the bearing， models encompassing gas lubrication with turbulence effects， foil structural mechanics， and the calculation of the average gas film temperature are introduced. Static and dynamic characteristics of the thrust gas foil bearing are studied and contrasted with various lubricant media. The impact of diverse structural parameters on the static and dynamic attributes of the gas foil bearing is analyzed. Results indicate that the physical property model presented in this paper attains high accuracy， boasting a correlation coefficient of 99.997%. The thrust gas foil bearing lubricated with S-CO2 exhibits enhanced load-bearing capacity， with potential for further improvement by adjusting the minimum initial gas film thickness or increasing the film thickness ratio within a suitable range. The dynamic stiffness and damping coefficient of the thrust gas foil bearing utilizing S-CO2 significantly surpass those employing air as the medium， underscoring its superior dynamic characteristics. Furthermore， a reduction in the minimum initial film thickness leads to a rapid increase in the dynamic stiffness coefficients and damping coefficients of the bearing.

Abstract:To improve the shooting stability of machine guns and firing accuracy， a single rod viscoelastic elastomer damper applied to 12.7 mm heavy machine guns was designed， which was simulated by the variable stiffness Kelvin model. The three important performance parameters （stiffness， damping coefficient， and initial pressure） of the viscoelastic elastomer damper were optimized and matched by orthogonal experiments， and a set of performance optimization parameters best matched the dynamics of the elastomer damper and the anti-aircraft machine gun were obtained. Finally， the dynamic performance of the optimized matching viscoelastic elastomer damper was compared with the spring damper. The results showed that the recoil force of the machine gun using the elastomer damper was smaller， the recoil speed changed more smoothly， and the muzzle fluctuation was smaller than that of the 12.7 mm machine gun equipped with the spring damper.

Abstract:This paper aims to investigate the impact of small-sized cutting serrated trailing edges on airfoil aerodynamic noise and to analyze the influence of the relationship between height and trailing edge boundary layer thickness on noise reduction effectiveness. Taking the NACA0012 airfoil as the research object， a hybrid computational aeroacoustics method was employed for simulation. Noise experiments on the NACA0012 airfoil were conducted at a wind speed of 20 m/s to validate the accuracy of the simulation method. By controlling the height and width of the serrations， the effect of different serrated trailing edge shapes on airfoil aerodynamic noise at angles of attack of 0° and 10° was studied. The results indicate that the noise reduction effect of serrated trailing edges is proportional to both height and width. The maximum noise reduction at a 0° angle of attack is 3.3 dB， while at a 10° angle of attack， it is 2.6 dB. The cutting serrated trailing edge structure increases the high-frequency components of flow noise， especially at a 0° angle of attack. Compared to embedded serrated trailing edges， cutting serrated trailing edges has a smaller limit for maximum noise reduction height.

Abstract:To investigate the influence of center distance error on tooth strength of small modulus gear and the applicability of GB/T 3480—2021 to the strength design of small modulus gear with center distance error， the calculation formulas of the contact coefficient， tooth profile coefficient， and stress correction coefficient are deduced by introducing center distance error. Then， the finite element model of small modulus gear with center distance error is established， and the verifying method to determine the mesh density is proposed. The contact stress and bending stress under different center distance errors obtained by the two methods are compared， and the results show that when the width of the element in the tooth profile contact area does not exceed 1/3 of the Hertz contact half-width， this contact model has a good calculation accuracy. The use of GB/T 3480—2021 to check the strength of small modulus gear with center distance error will produce a redundant design； when the center distance error reaches 1.33%， the maximum change of the contact stress amplitude is 4.23%， and the maximum change of the bending stress amplitude is more than 16.25%. The influence of center distance error on the bending stress of small modulus gear is more significant than the contact stress.

Abstract:To study the Electromagnetic Interference （EMI） characteristics of the Fuel Cell Controller （FCU）， this paper develops an equivalent radiation source using the differential evolution algorithm and measures the magnetic field of the FCU controller based on the near-field scanning method. By comparing the magnetic field generated by the equivalent radiation source with the measurement， the average error in X， Y， and Z direction at each frequency point is about 3%. Then， the far-field radiation in the half-space above the PCB board is simulated with the reconstructed model， and the results show that the average error between the simulated electric field and the measured electric field is around 4.1 dB， and the overall trend tends to be consistent in the measurement band range， which shows the accuracy of the equivalent radiation source reconstructed based on differential evolution algorithm. Thus， this method can be used for predicting the effects of the radiation sources. Furthermore， this paper also investigates the effect of the metal shell based on the reconstructed equivalent radiation source， and the results show that far-field radiation of the PCB board is reduced by about 10 dB. Thus， the metal shell can effectively reduce the radiation interference generated by the FCU controller.

Abstract:Aiming at the influence of the thermoelectric leg size on the overall thermal stress field of the module in thermoelectric refrigeration modules， this paper takes the C-31106 thermoelectric refrigeration module as the research object and establishes a thermoelectric-mechanical coupled multiphysics field model composed of 31 pairs of thermocouples. Using the finite element simulation method， considering the existence of brazing layers and introducing the Anand modified constitutive equation characterizing the viscoplastic material， the thermoelectric model under three mounting conditions is established， and the influence laws of the height and the cross-section side length of thermoelectric legs on the temperature field and mechanical properties of the thermoelectric module under different currents are analyzed. The results show that when the thermoelectric leg is at the optimal height， the larger the cross-section side length of the thermoelectric leg is （within a given range）， the more favorable it is to improve the mechanical reliability of the thermoelectric module. When the operating current is 2.6 A and the cross-section side length is increased from 0.99 mm to 1.09 mm， the maximum von Mises stresses at the hot and cold sides are reduced by 74.67% and 22.60%， respectively. The mechanical reliability of the thermoelectric module can be improved by using fixed constraints and mechanical press-fit mounting for the cold and hot sides of the module， respectively. The maximum von Mises stresses on the hot and cold sides of the module are reduced by 48.76% and 74.02%， respectively， compared with the fixed restraints on both sides.

Abstract:An improved Retinex low-illumination image enhancement algorithm is proposed for the balanced enhancement of low-illumination images while retaining their more detailed information. The algorithm is based on the HSV （Hue， Saturation， Value） color space and enhances the separated luminance and saturation components. First， the brightness component is optimized using Contrast Limited Adaptive Histogram Equalization （CLAHE） to make the image closer to the uniformly illuminated scene， and the saturation component is corrected using Adaptive Gamma. Then， a Block-matching and 3D Filtering （BM3D） algorithm is used to estimate the illumination component， the corresponding reflection component is obtained， and an improved Gamma transform function is proposed to enhance the luminance component based on the information of the illumination component. Meanwhile， the Gabor filter and Canny algorithm are used to extract the details of the original image， and a detail enhancement strategy is proposed to enhance the reflection component and its texture details. Finally， the components are fused with multiple weights， and then the enhanced image is transformed back to RGB space. Experimental results show that the proposed algorithm has better enhancement effect and universality than automatic color equalization， adaptive local tone mapping， low-illumination image enhancement， and multi-scale Retinex with color restoration. After enhancement， the original image showed significant improvements in information entropy，peak signal-to noise ratio， structural similarity index，universal image quality index，average gradient，while the root mean square error decreased significantly.

Abstract:To reduce the current unobservable region within the spatial voltage vector synthesis region and increase the output voltage modulation ratio， a strategy of three-phase current reconstruction for single resistor sampling with high modulation ratio is proposed. The switching state phase shift process is divided into three stages according to the difference between the switching state and actual hardware sampling delay， and the process with difference switches is carried out， which increases the output voltage modulation ratio without any modification of the original circuit topology. The currents are sampled during the first half Pulse Width Modulation （PWM） period and reconstructed in the second half PWM period. Meanwhile， it fully utilizes the turn-on time of the zero vector， reduces the unobservable area， and realizes the complete reconstruction of the three-phase current. Finally， the feasibility and effectiveness of the strategy are verified by simulations and experiments.

Abstract:To address the circulating current issue among parallel battery clusters in energy storage systems， a series-connected step-up partial-power equalizer is proposed， which optimizes transmission efficiency and power density of the equalizer by introducing partial power conversion technology. Aiming at the control problem of two different power flows in the partial-power equalizer， a duty-cycle-based power flow control method is proposed， and a detailed analysis of the equalizer’s working states under the proposed control method is conducted， which realizes effective control and bi-directional flow capability for both the base power flow and the adjustment power flow. For the degradation of system performance caused by the inconsistency of battery clusters， a parallel-battery-clusters power equalization control method is proposed， which suppresses the power circulation issue among parallel battery clusters. Finally， experimental results verify the effectiveness of the proposed partial-power equalizer and its control method.

Abstract:To realize the rapid online diagnosis and alarm of the faults of power distribution equipment and water pumps in the pumping house of the water plant and its secondary booster pumping house so as to guarantee the safe operation of the pumping house system， an online diagnosis method of equipment in the pumping house is proposed based on the multipoint voltage and current information fusion. Based on the distribution equipment and pumps in the pumping house， the voltage and current characteristics of common faults in the power distribution equipment and water pumps in the pumping house， as well as the mutual influence mechanism of these faults， are systematically analyzed for the first time. The real-time voltage and current values of multiple key nodes in the distribution line are fused to extract the fault characteristics of six types of faults， including voltage overruns in the main circuit of the pumping house distribution， open air switches or contactors in the distribution line， open pump motor windings， imbalanced pump motor winding， inter-turn short circuit， pump blocking， connection break between the motor and pump， so as to realize the online diagnoses of these six types of faults. The implementation conditions of the method， the principle of implementation， and the specific steps are elaborated. Finally， MATLAB/Simulink is used to build a simulation model， which is experimentally verified. The simulation results show that the method can effectively diagnose the pumping house equipment faults， overcome the shortcomings of time-consuming and untimely offline analysis in the labor-intensive manual diagnosis， and provide effective protection for the safe operation of the distribution equipment and pumps in the water plant and its secondary booster pumping house.

Abstract:In response to the issues of neglecting prior information and low computational efficiency of the traditional Singular Value Thresholding （SVT） algorithm in power load data recovery， a novel improved SVT algorithm based on phase space reconstruction and adaptive variable step length is proposed. To address the problem of neglecting prior information in traditional SVT， a phase space reconstruction algorithm is introduced to map the original missing data into a high-dimensional space， leveraging data correlation and structural features as prior knowledge for subsequent data recovery algorithms. By combining logarithmic and sigmoid functions to construct the variable step length base function， and utilizing geometric progression to enhance the initial step length， an adaptive variable step length SVT algorithm is built to overcome the low computational efficiency issue of traditional SVT in large-scale data scenarios. Comparative experimental analysis is conducted using multiple publicly available power load datasets and various commonly used power load data recovery algorithms. The results demonstrate that the improved SVT algorithm achieves better data recovery performance， with enhanced convergence speed， accuracy， and stability， showcasing strong engineering practicality.

Abstract:To accurately analyze the impact of transient signals on the ZPW-2000A track circuit， this paper considers the frequency-varying loss caused by the skin effect in transmission lines and establishes a fractional-order model of the Multi-conductor Transmission Line （MTL） in the track circuit. Aiming at the transient response analysis under high-frequency loss of the ZPW-2000A track circuit， a method for solving the voltage at the receiving end of the track circuit in the time domain is proposed. Based on transmission line theory， a model of the track circuit transmission line system is established， and a fractional-order transmission line equation is formulated and solved according to the obtained model. First， the partial differential equations of the fractional-order model of the track circuit transmission line are discretized into ordinary differential equations using the Compact Finite Difference Method （CFD） in the spatial domain. Then， the G-L fractional-order definition is utilized to transform these equations into integer-order ordinary differential equations. Finally， the voltage and current responses at each point on the transmission line are obtained by combining the precise integration method with recursive convolution. Under the excitation of double-exponential signals， the accuracy of this method is verified by comparison with the state variable method， with the error between the two solutions being within 7%， and the method presented in this paper requires less time. The variation of rail overvoltage under different transient signal inputs is analyzed， revealing that the higher the signal frequency， the smaller the amplitude of rail overvoltage； the greater the ballast resistance， the larger the amplitude of rail overvoltage and the longer it takes for the signal to decay to stability.