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Copyright of Rolling Stock (1002-7602) is the property of Rolling Stock Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study explores a more effective obstacle avoidance method for autonomous driving based on the monocular vision system of YOLOv5. The study utilizes the YOLOv5 model to detect obstacles and road signs in the environment in real-time, including vehicles, pedestrians, traffic signals, etc., identifying objects of different sizes and angles, providing accurate obstacle avoidance decision inputs. Then, we use a path planning algorithm based on deep reinforcement learning to combine the detected obstacle information with the current state of the vehicle, dynamically generating safe and efficient driving paths. In order to further improve the obstacle avoidance effect, a monocular visual autonomous driving obstacle avoidance aggregation network was introduced in the study, and the MMA (Multi lane monocular visual autonomous driving) obstacle avoidance method was established. The future movement trend of obstacles was predicted by setting an improved monocular obstacle avoidance loss function to sense historical data and the environment. The experimental results show that MMA has significantly enhanced obstacle avoidance and driving efficiency. The accuracy of the MMA obstacle avoidance method fluctuates between 78.76 % and 88.26 %, showing the best overall performance. The accuracy also shows an upward trend with the increase of the data sample size.

To further optimize the automotive AEB-P (autonomous emergency braking for pedestrian) control algorithm, an AEB-P hierarchical control strategy that integrates driving comfort and pedestrian injury risk was proposed. A braking safety distance model considering the driver′s comfort during braking was designed for the AEB-P evaluation standard of C-NCAP. The weight coefficient adjustment strategy was obtained by introducing fuzzy rules to comprehensively consider the risk of pedestrian injury and scenario working conditions. Based on this, the adaptive weight coefficient MPC (model predictive control) upper controller was designed, and the PID (proportion integration differentiation) lower controller was used to correct the actual deceleration of the auto-vehicle. The vehicle longitudinal dynamics model was established and the test scenario and control algorithm were constructed through CarSim and Matlab/Simulink, then the proposed method and the fixed TTC (time to collision) threshold algorithm were compared through hardware-in-the-loop experiments. The results show that the proposed control algorithm can effectively avoid collision in 93.4% of the test conditions, while the fixed TTC threshold algorithm has a successful rate of only 43.75% in obstacle avoidance. Compared with the traditional control strategy, the proposed method can maintain a more stable minimum distance between the vehicle and the pedestrian in front of it, with better robustness, which provides a reference basis for the AEB-P control theory.

Aiming at the problem that frequently train traction starting causes wheel wear and fatigue damage, on the basis of the constant traction force, the influence of the speed at the end of the constant power section of different traction characteristic curves on wheel wear and fatigue was studied. SIMPACK and MATLAB software were used for co-simulation to establish the dynamic model of urban rail trains(URTs) under different traction characteristics and the wheel wear model based on Archard. The influence of the speed at the end of the constant power section of the traction characteristic curve on the wheel-rail creepage, wheel wear depth, wear area and fatigue index of URTs under different starting torque of traction motor was analyzed. The results show that during the train traction starting process, the larger the starting torque of the motor, the greater the wheel-rail creepage, and the wheel wear depth and wear area, while the smaller the fatigue index; For agiven starting torque of the motor, with the increase of the speed at the end of the constant power section of the train traction characteristic curve, the wheel-rail creepage, and the wheel wear depth and wear area also increase, while the fatigue index decreases.When the starting torque of the motor increases from 800 N·m to 1 400 N·m, the maximum growth rates of wheel wear depth and wear area are 6.9% and 12.6%, respectively, while the maximum decline rate of fatigue index is 7.2%; When the speed at the end of the constant power section increases from 50 km/h to 80 km/h, the maximum growth rates of wheel wear depth and wear area are 4.4% and 4.3%,respectively, and the maximum decline rate of fatigue index is 1.9%.The effects of starting torque and the speed at the end of the constant power section on wheel wear and fatigue are obtained, which provides reference for the design of vehicle traction characteristics, motor control and wheel operation and maintenance.

The moment of inertia of the primary flywheel and the secondary flywheel in a dual mass flywheel (DMF) directly affects the vibration damping performance in an automotive driveline. To enable better minimization of vibration and noise by changing the moment of inertia of the DMF to adjust the frequency characteristics of the automotive driveline, a new variable inertia DMF structure is proposed by introducing electromagnetic devices. The finite element simulation model of the electromagnetic field of an electromagnetic device is established, the electromagnetic field characteristics in the structure are analyzed, and the variation in the electromagnetic force under different air gaps and current conditions is obtained. The electromagnetic force test system of the electromagnetic device is constructed, and the validity of the finite element simulation analysis of the electromagnetic field of the electromagnetic device is verified. A mechanical model of the electromagnetic device is established to analyze the characteristics of the displacement of the moving mass in the structure as well as the variation in the moment of inertia of the DMF at different rotational speeds and currents. The maximum adjustable proportion of its moment of inertia can reach 15.07%. A torsional model of the automotive driveline is established to analyze the effect of variable inertia DMF on the resonance frequency of the system under different currents. The results show that the electromagnetic device introduced in the DMF can realize the active adjustment of the moment of inertia and enable the resonance frequency to decrease with increasing rotational speed, which expands the idea of optimizing the vibration damping performance of the DMF and provides a reference for better control of the torsional vibration of the automobile or other mechanical transmission systems. [ABSTRACT FROM AUTHOR]

By means of material testing, truck testing and numerical simulation, the structural parameters of the shrink tube anti-climb device for high-speed trains were determined. The effects of cone angle, tube thickness, friction coefficient and axial length of the friction cone on the crashworthiness of the shrink tube were studied, and the main causes were analyzed. Using cone angle and tube wall thickness as input variables, and peak crush force, mean crash force and specific energy absorption as crashworthiness indexes, a proxy model was constructed using a radial basis function. The global response surface methodology was adopted to optimize the design of the shrink tube's structural parameters. The results showed that the crashworthiness of the shrink tube was positively correlated with the cone angle, the thickness of the shrink tube and the friction coefficient, and the influence decreased successively, while the influence was negatively correlated with the axial length of the friction cone, which had the least influence. Through the optimized design, the peak force of the shrink tube increased by only 5.41%, while the specific energy absorption increased by 31.03%. Additionally, the mean force was closer to the technical requirements of 600 kN, and the crashworthiness was optimized. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Hebei University of Science & Technology is the property of Hebei University of Science & Technology, Journal of Hebei University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Hebei University of Science & Technology is the property of Hebei University of Science & Technology, Journal of Hebei University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the problem that during continuous braking of pure electric commercial vehicles, low air source pressure will lead to slower braking force response speed of drive axle coupling and affect braking energy recovery efficiency, a scheme of uncoupled braking energy recovery system (URBS) based on proportional relay valve was proposed. Firstly, based on the hysteresis characteristics of the proportional relay valve, the feed-forward-single neuron PID control method was adopted to realize the accurate output of braking air pressure. Secondly, taking the battery SOC and vehicle speed as the constraints, the pressure supply mode was determined according to the pressure signal of the air source, and the uncoupled braking energy recovery control strategy was formulated. Finally, a joint simulation platform was built based on AMESim, MATLAB/Simulink and TruckSim, and a single braking condition and cyclic conditions were selected to verify the effect of the braking force coupling and the braking energy recovery of the system. The results show that URBS based on proportional relay valve can achieve rapid response of coupled braking force, with the time of less than 0.1 second to reach 75% of steady-state pressure value. The effective braking energy recovery rates under CHTC-HT（China heary-duty commercial vehicle test cycle for heavy truck) and C-WTVC(China world transient vehicle cycle) conditions are 10.13% and 17.17%, respectively. The proposed URBS scheme can effectively improve the response speed and coupling accuracy of coupled braking force of the drive axle, and can provide reference for the design of pneumatic URBS schemes for pure electric commercial vehicles.

Severe plastic deformation is caused by the collision between road obstacles and the battery pack of electric vehicles, and it is one of the key factors of battery short circuit failure. Based on a certain type of electric vehicle, an explicit dynamic analysis method is used to establish a vehicle system dynamic model, and the effectiveness of the model is verified through a comparative analysis with tests. Under two typical operating conditions of the bottom scraping and the bottom impacting, the influence of different obstacle heights, positions, and vehicle velocities on the impact load between the battery pack and spherical obstacles is studied. Under the bottom impact condition, the battery pack mainly bears the vertical impact load. When the obstacle collides with different modules, the peak of vertical impact load linearly increases as the vertical distance between the obstacle and the battery pack increases. Under the bottom scraping condition, the battery pack mainly bears vertical and longitudinal impact loads. As the height of the obstacle increases, the peaks of vertical and longitudinal impact loads increase linearly, and the increase of longitudinal impact loads is greater than that of vertical loads. The vertical and longitudinal load peaks are linearly related to the square of velocity. When the velocity increases from 10 km/h to 70 km/h, the vertical and longitudinal loads increase by 296.2 % and 256.4 %, respectively. In addition, the change in the lateral position of the obstacle has a significant influence on the impact load under two typical operating conditions, and the closer it is to the inside of the vehicle, the greater the peak of the impact load. [ABSTRACT FROM AUTHOR]

Selective laser melting (SLM) technology has broad application prospects in the fields of metal additive manufacturing, aerospace vehicles, etc. The research progress of SLM316 stainless steel materials in terms of process, structure, properties, and applications were summarized, and the existing problems and solutions were analyzed and explored. The problems in the production process, product quality, performance stability, and post-treatment process of SLM were analyzed. The microstructure and mechanical properties of 316 stainless steel additive were further studied. influences of the process on the microstructure and properties were analyzed. By reasonably controlling the laser additive manufacturing process, it can provide support for the application of the technology in the industry. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Beijing University of Technology is the property of Journal of Beijing University of Technology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the demand for subjective evaluation of driveability for fuel cell vehicles, the modeling and evaluation method of driveability for fuel cell vehicles were studied in this paper. Firstly, a real-time model of the fuel cell vehicle powertrain system was established, which included the fuel cell model, power battery model, DC/DC converter model and drive motor model. Secondly, it was integrated with the vehicle dynamics model to form a virtual prototype of a fuel cell vehicle. And a virtual subjective evaluation platform for fuel cell vehicles was built by combining the virtual prototype and high-fidelity driving simulator. Thirdly, a subjective evaluation method of driveability for fuel cell vehicles was proposed, which included the starting performance, acceleration performance, uniform speed performance and tip-in/tip-out performance. Finally, the paper used the platform and method mentioned above to conduct subjective evaluations of the fuel cell vehicles. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Hebei University of Science & Technology is the property of Hebei University of Science & Technology, Journal of Hebei University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With the rotating-arm axis box as the research object, we established a test method in the original place of damage of the axis box that can reproduce the suspension parameter conditions of the bogie frame. First, this method establishes a real axis box mechanical model based on the suspension parameters of the axis box assembly conditions and calculates the load distribution relationship of the axis box through this model. Second, through a comparison of test data under different tooling conditions, it was verified that the distribution relationship had a great influence on the strength evaluation of the axis box body. Then, the single-axis box test method was simulated and optimized to determine the distribution of test loads and constraint conditions. The calculation results better restored the axis box test data under in situ conditions and derived a single-axis box test method with high accuracy. The lowest damage coverage was 1.01. The mechanical modeling and test optimization approach not only improves damage-based life assessment but also tunes up the efficiency of axis box testing. [ABSTRACT FROM AUTHOR]

The moment of inertia of the primary flywheel and the secondary flywheel in a dual mass flywheel (DMF) directly affects the vibration damping performance in an automotive driveline. To enable better minimization of vibration and noise by changing the moment of inertia of the DMF to adjust the frequency characteristics of the automotive driveline, a new variable inertia DMF structure is proposed by introducing electromagnetic devices. The finite element simulation model of the electromagnetic field of an electromagnetic device is established, the electromagnetic field characteristics in the structure are analyzed, and the variation in the electromagnetic force under different air gaps and current conditions is obtained. The electromagnetic force test system of the electromagnetic device is constructed, and the validity of the finite element simulation analysis of the electromagnetic field of the electromagnetic device is verified. A mechanical model of the electromagnetic device is established to analyze the characteristics of the displacement of the moving mass in the structure as well as the variation in the moment of inertia of the DMF at different rotational speeds and currents. The maximum adjustable proportion of its moment of inertia can reach 15.07%. A torsional model of the automotive driveline is established to analyze the effect of variable inertia DMF on the resonance frequency of the system under different currents. The results show that the electromagnetic device introduced in the DMF can realize the active adjustment of the moment of inertia and enable the resonance frequency to decrease with increasing rotational speed, which expands the idea of optimizing the vibration damping performance of the DMF and provides a reference for better control of the torsional vibration of the automobile or other mechanical transmission systems.

By means of material testing, truck testing and numerical simulation, the structural parameters of the shrink tube anti-climb device for high-speed trains were determined. The effects of cone angle, tube thickness, friction coefficient and axial length of the friction cone on the crashworthiness of the shrink tube were studied, and the main causes were analyzed. Using cone angle and tube wall thickness as input variables, and peak crush force, mean crash force and specific energy absorption as crashworthiness indexes, a proxy model was constructed using a radial basis function. The global response surface methodology was adopted to optimize the design of the shrink tube’s structural parameters. The results showed that the crashworthiness of the shrink tube was positively correlated with the cone angle, the thickness of the shrink tube and the friction coefficient, and the influence decreased successively, while the influence was negatively correlated with the axial length of the friction cone, which had the least influence. Through the optimized design, the peak force of the shrink tube increased by only 5.41%, while the specific energy absorption increased by 31.03%. Additionally, the mean force was closer to the technical requirements of 600 kN, and the crashworthiness was optimized.

Wheelset structural flexibility, that is the elastic deformation of the wheelset as a structure, has an important influence on the dynamic properties of railway locomotive vehicles at medium and high frequencies. Based on the practical structural parameters, this paper proposes a multi-degree of freedom rigid-flexible coupling dynamic model of a wide-gauge freight electric locomotive with C0-C0 bogies with an axle suspension driving system. The wheelset with the interference-fit large gear is made flexible using the finite element method, and then the rigidflexible coupling vehicle model with elastic wheelsets is established in the software SIMPACK 2020. A short-wave irregularity superposed on the American fifth-grade track irregularity is used as the track excitation to study the performance at higher frequencies. From the modal analysis of the vehicle, it is obtained that the lowest frequency at which the elastic deformation of the wheelset occurs is 24.631 Hz. The lateral vibration responses of the vehicle with elastic wheelsets are reduced mainly in the frequency range of 30-150 Hz. There are two resonances in the lateral vibration responses at the mode frequencies of the vehicle over 50 Hz, which are close to the wheelset's first mode frequency. Taking the ГOCT standard of wide-gauge countries as the main reference, simulations are separately taken in straight-line and curved-line cases. Results show that the wheelset structural flexibility mainly influences the vehicle lateral stability and safety. [ABSTRACT FROM AUTHOR]

In order to improve the heavy-duty transportation vehicle drivers′ riding comfort and driving safety, a fuzzy sliding mode controller for semi-active suspension based on a new reaching law was put forward. Firstly, to solve the problem of real-time measurement of road signals, based on the improved reference ceiling model, the motion state of the unsprung mass was directly used as the input of the control system; secondly, aiming at the problems of chattering and slow convergence speed of the system caused by sliding mode control, a new reaching law of the saturation function of the variable boundary layer was proposed, and the fuzzy control and sliding mode control were combined to ensure the control accuracy and control robustness; finally, the semi-active suspension of the heavy-duty transport vehicle was simulated. The results show that compared with traditional fuzzy sliding mode control, the vertical acceleration of the body is reduced by 789%, the dynamic load of the wheel is reduced by 136%, and the dynamic deflection of the suspension is reduced by 314%. The proposed controller can improve the riding comfort which is evaluated by the vertical acceleration of the body and the dynamic deflection of the suspension, and the driving safety which is evaluated by the dynamic load of the wheel, providing some reference for the study of the intelligent control of semi-active suspension system.

Aiming at the problem that the current ABS control algorithm cann't make full use of the ground braking force to complete the braking when the complex road surface is in emergency braking, the ABS sliding mode variable structure control method based on road surface identification is proposed. Combined with the in-wheel motor of in-wheel motor electric vehicle, a coordinated control method of motor hydraulic composite is designed. Based on the fuzzy logic control method, the road adhesion coefficient is estimated to realize the identification of typical roads and dynamically obtain the optimal slip rate of different roads. The ABS sliding mode variable structure controller is designed with the optimal slip ratio and the actual slip ratio as input, and the saturation function is used to replace the sign function in the traditional sliding mode variable structure control to weaken the ' chattering ' phenomenon in the sliding mode variable structure control, and then the ABS controller is designed. Taking the experimental prototype vehicle driven by four-wheel hub motor as the research object, an eight-degree-of-freedom dynamic simulation model of the whole vehicle is established. Compared with the traditional PID controller, the braking time is shortened by 0.2 s and the braking distance is shortened by 2.3 m, which shows the feasibility of the designed controller. Through the simulation braking experiment of the docking road, the adaptability and real-time performance of the ABS sliding mode controller are verified, and the importance of the road adhesion coefficient identification to the ABS controller is verified. [ABSTRACT FROM AUTHOR]

Aiming at the power cycle problem existing in the available planetary gearset power-split hybrid electric vehicle,a new configuration of single planetary gearset power-split hybrid electric vehicle combined with automatic clutch,automatic brake and reduction gear pair was proposed in order to improve the vehicle power performance and economical performance.The key assembly parameters were matched,the structural design of the planetary gearset gears was completed,and the strength analysis was carried out based on ANSYS.The control strategy aiming at the best fuel economy of the engine was proposed,and the co-simulation platform was built based on AVL Cruise and MATLAB/Simulink to verify the vehicle power performance and economical performance.The results show that compared with the available planetary gearset power-split hybrid configuration,the maximum speed of the vehicle with the new configuration is increased by 3.8%,the acceleration time from 0 to 100 km/h is shortened by 7.64%,the maximum climbing degree is increased by 18.09%,and the comprehensive fuel consumption per 100 km under conditions WLTC is decreased by 14.88%.Using the new configuration can eliminate the power cycle and effectively improve the vehicle power performance and economical performance,which provides some reference for the design of other hybrid configurations.

Copyright of Journal of Chongqing University of Technology (Natural Science) is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Hebei University of Science & Technology is the property of Hebei University of Science & Technology, Journal of Hebei University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Automobile Technology & Material is the property of Automobile Technology & Material Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the problem of early damage detection of axle box bearings, a diagnosis model based on improved multiscale dispersion entropy (IMDE) and support vector machine is proposed to effectively identify the health state of bearings by extracting key information from vibration signals. This method mainly considers the shortcomings of traditional multi-scale dispersion entropy (MDE), such as the increase of entropy standard deviation, the confusion of distribution and the obvious fluctuation caused by the problem of data point coincidence and the increase of coarse-graining scale. The algorithm is improved by optimizing the coarse-graining procedure and the dispersion entropy. Then, a practical example is given to verify the vibration data of high -speed train axle box bearing under different operating conditions by experiments. The results show that the standard deviation of IMDE is smaller and the robustness is better than MDE, and the classification results of support vector machine show that IMDE has higher diagnosis accuracy. [ABSTRACT FROM AUTHOR]

Aiming at the demand for subjective evaluation of driveability for fuel cell vehicles, the modeling and evaluation method of driveability for fuel cell vehicles were studied in this paper. Firstly, a real-time model of the fuel cell vehicle powertrain system was established, which included the fuel cell model, power battery model, DC/DC converter model and drive motor model. Secondly, it was integrated with the vehicle dynamics model to form a virtual prototype of a fuel cell vehicle. And a virtual subjective evaluation platform for fuel cell vehicles was built by combining the virtual prototype and high-fidelity driving simulator. Thirdly, a subjective evaluation method of driveability for fuel cell vehicles was proposed, which included the starting performance, acceleration performance, uniform speed performance and tip-in/tip-out performance. Finally, the paper used the platform and method mentioned above to conduct subjective evaluations of the fuel cell vehicles.

In this paper, the least squares method is used to determine the vertical height of the road space domain. Based on the road estimation method, the active suspension control mode switching model is constructed, and the dynamic characteristics of the vehicle in comfort, safety, and integrated modes are analyzed. The vibration signal is collected by the sensor, and the parameters such as vehicle driving conditions are solved for in reverse. A control strategy for multiple mode switching under different road surfaces and speeds is constructed. At the same time, the particle swarm optimization algorithm (PSO) is used to optimize the weight coefficients of LQR control under different modes, and the dynamic performance of vehicle driving is comprehensively analyzed. The test and simulation results show that the road estimation results under different speeds in the same road section are very close to the results obtained by the detection ruler method, and the overall error is less than 2%. Compared with the active suspension controlled by passive and traditional LQR, the multi-mode switching strategy can achieve a better balance between driving comfort and handling safety and stability, and also improve the driving experience more intelligently and comprehensively. [ABSTRACT FROM AUTHOR]

As one of the critical issues in operations management, spare parts planning classification systems based only on cost may not withstand the test of time because of continuing technological advancement or environmental degradation. This study, however, emphasizes using failure mode effect and criticality analysis (FMECA) as a basis for designing an ABC classification system that is capable of more accurately determining critical equipment and making maintenance more efficient. In the proposed methodology, risk priority numbers (RPN) and criticality as an index of safety and reliability can be obtained using a structured failure analysis technique. These indexes can be added to the economic indicator of maintenance cost, and then a classification model of spare parts can be established according to a comprehensive scoring method. The model is calibrated by using case data from a bus braking system, and the components of the braking system are compared and analyzed. The results show that the improved ABC classification method reduces the proportion of key and main components. This method can make maintenance work more efficient, targeting the most critical components, and can reduce administrative costs for enterprises.

A reasonable braking timing sequence plays an important role in the braking stability of a semi-trailer train, but there is still a lack of objective and comprehensive scientific evaluations of braking stability as shown by the braking timing sequence. Aiming at this problem, through the analysis of relevant regulations and standards at home and abroad, an evaluation index hierarchy model of the semi-trailer train braking timing sequence is constructed. The fuzzy analytic hierarchy process is used to determine the weight of the evaluation index of each level of the braking timing sequence, and a comprehensive evaluation is obtained. In order to determine the optimal braking timing sequence of the train during braking, a simulation model was established and simulated. Through the combination of index weight and simulation data, the model can provide a theoretical basis for the subsequent study of the optimal braking timing sequence of semi-trailer trains running under different working conditions. [ABSTRACT FROM AUTHOR]

Copyright of Rolling Stock (1002-7602) is the property of Rolling Stock Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Hebei University of Science & Technology is the property of Hebei University of Science & Technology, Journal of Hebei University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the problem of detecting parking space lines in automatic parking systems, a parking space line detection method based on edge formation was proposed. Firstly, the image was preprocessed, and the traditional Canny edge detection operator was improved. The 45° and 135° direction templates were added to calculate the gradient amplitude and direction to reduce noise interference and improve image quality. Then, the edge image was searched for 8 neighborhoods and clustering and grouping, removing shorter straight lines, and solving the connection problem. Finally, using the gradient direction difference of two adjacent pixels in each edge group to remove the edge groups that were not characteristic of the parking space line, by doing random Hough transform for each edge group, and using Prior knowledge and least squares fitting method get the parking space line. The experimental results show that compared with the traditional Hough transform, the algorithm can accurately detect the parking line in different situations and has better real-time performance. [ABSTRACT FROM AUTHOR]

During the present study, a double groove texture was designed on the surface of a piston ring to improve the sealing performance between the piston ring and cylinder liner. The experimental design method was used to fabricate the test plan according to the groove width, depth, and spacing. By using the thermal–structural coupling analysis method, the finite element analysis of the standard piston ring and the textured piston ring was carried out to simulate the deformation state of the cylinder liner system of the piston ring group during the working stroke. The piston rings with different parameters designed by the test scheme were manufactured by wire electrical discharge machining, and the self-made experiment device carried out the sealing test. The results showed that the groove texture could improve the sealing performance of the piston ring, and the analyzed results demonstrated that the groove texture had little effect on the maximum deformation of the piston ring. Still, it could significantly reduce the minimum deformation of the piston ring group. A piston ring with groove texture would improve the sealing performance and reduce the deformation during the work stroke. During the test, the average deformation of the No.7 piston ring group, with a groove depth of 1 mm, a groove width of 0.5 mm, and a groove spacing of 0.1 mm, was the smallest, about 29.6% lower than that of the standard piston ring group. The sealing performance of the No.7 piston ring group was the best, and the reduction rate of the top gas leakage rate was 52.18%. During the present study, the sealing performance of the piston ring was improved by designing the grooved structure on the piston ring surface, thereby improving the fuel economy and power performance of the engine. The present study could provide a reference for the engineering field to design a piston ring with high sealing performance. [ABSTRACT FROM AUTHOR]

A new torque optimization control method based on predictive control for emergency braking of a four-wheel hub electric vehicle compound braking（hydraulic braking and regenerative braking）system is proposed. The torque optimization controller can quickly track and respond to the optimal slip ratio stable area of the vehicle under different pavement friction conditions. At the same time, an energy recovery trend optimization item is added into the control objective function so as to adjust the vehicle’s energy recovery target quickly and dynamically. By adjusting and optimizing the weight of the objective function, braking safety is achieved and the energy recovery capability of the vehicle is improved as well. A vehicle model was established in Carsim, and a joint simulation platform was built with Simulink. The results show the superiority of the proposed torque optimization method. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Hebei University of Science & Technology is the property of Hebei University of Science & Technology, Journal of Hebei University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)