Simulation driven design method which use multiple optimization methods can effectively promote innovative structural design and reduce product development cycle. Meanwhile, the submodel technology which proceed more detailed simulation and optimization analysis can enormously improve the efficiency of modeling and solving. This study establishes a general workflow of structural optimization for stainless-steel metro bolster by combining the simulation driven design method and the submodel technology. In the submodel definition phase, the end underframe submodel which contains the bolster is obtained based on the whole car body FE model, and the effectiveness of the end underframe submodel is also proved. In the conceptual design phase, the topology path inside the bolster is obtained by topology method and the optimized structure of the inner ribs inside the bolster is determined according to manufacturing processes and design experiences. In the detailed design phase, the thicknesses of each part of the bolster are determined by size optimization. The simulation analyses indicate that the requirements of static strength and fatigue strength are fulfilled by the optimized bolster structure. Besides, the weight can be reduced by 11.18% and the weld length can be decreased by 17.79% compared with the original bolster structure, which means that not only the lightweight design goal is achieved, but also the welding quantity and manufacturing difficulty are greatly reduced. The results show the effectiveness of the simulation driven design method based on the submodel technology in the structural optimization for key parts of the rail transit vehicles.
{"title":"Structural optimization design of a bolster based on simulation driven design method","authors":"Xinkang Li, Fei Peng, Zeyun Yang, Yong Peng, Jiahao Zhou","doi":"10.1093/tse/tdac075","DOIUrl":"https://doi.org/10.1093/tse/tdac075","url":null,"abstract":"\u0000 Simulation driven design method which use multiple optimization methods can effectively promote innovative structural design and reduce product development cycle. Meanwhile, the submodel technology which proceed more detailed simulation and optimization analysis can enormously improve the efficiency of modeling and solving. This study establishes a general workflow of structural optimization for stainless-steel metro bolster by combining the simulation driven design method and the submodel technology. In the submodel definition phase, the end underframe submodel which contains the bolster is obtained based on the whole car body FE model, and the effectiveness of the end underframe submodel is also proved. In the conceptual design phase, the topology path inside the bolster is obtained by topology method and the optimized structure of the inner ribs inside the bolster is determined according to manufacturing processes and design experiences. In the detailed design phase, the thicknesses of each part of the bolster are determined by size optimization. The simulation analyses indicate that the requirements of static strength and fatigue strength are fulfilled by the optimized bolster structure. Besides, the weight can be reduced by 11.18% and the weld length can be decreased by 17.79% compared with the original bolster structure, which means that not only the lightweight design goal is achieved, but also the welding quantity and manufacturing difficulty are greatly reduced. The results show the effectiveness of the simulation driven design method based on the submodel technology in the structural optimization for key parts of the rail transit vehicles.","PeriodicalId":52804,"journal":{"name":"Transportation Safety and Environment","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41878693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhao Liu, Feng Liu, S. Yao, Da-wei Chen, Ming-zhi Yang
The length of the high-speed railway tunnel is an important factor affecting the transient pressure. When the tunnel length is the most unfavorable, the transient pressure changes in the tunnel and on the surface of the train are the most severe, which may affect the safe operation of the train or damage the structure in the tunnel. Based on the three-dimensional, compressible, unsteady N-S equation and finite volume method, this paper uses the CFD numerical simulation method to study the change and amplitude distribution of the transient pressure on the train surface and the tunnel when the high-speed train passes through the most unfavorable length tunnel. And a fast calculation method is proposed to save the cost of calculation, it has a great applicability of pressure amplitude. The results show that the pressure distribution in the tunnel and on the surface of the train is affected by the train speed, the length of the train and the position of the measuring point. The minimum negative peak value in the tunnel appears at the position where the superposition phenomenon is most severe, and the position will change with the speed of the train. There are two negative peak waveforms of the train surface pressure, and the first waveform is greatly affected by the train speed. It improves a reference for studying the strength requirement of the most unfavorable length tunnels and trains and ensures the safe operation of trains in tunnels of different lengths.
{"title":"Research on numerical simulation of transient pressure for the high-speed train passing through the most unfavorable length tunnel","authors":"Zhao Liu, Feng Liu, S. Yao, Da-wei Chen, Ming-zhi Yang","doi":"10.1093/tse/tdac059","DOIUrl":"https://doi.org/10.1093/tse/tdac059","url":null,"abstract":"\u0000 The length of the high-speed railway tunnel is an important factor affecting the transient pressure. When the tunnel length is the most unfavorable, the transient pressure changes in the tunnel and on the surface of the train are the most severe, which may affect the safe operation of the train or damage the structure in the tunnel. Based on the three-dimensional, compressible, unsteady N-S equation and finite volume method, this paper uses the CFD numerical simulation method to study the change and amplitude distribution of the transient pressure on the train surface and the tunnel when the high-speed train passes through the most unfavorable length tunnel. And a fast calculation method is proposed to save the cost of calculation, it has a great applicability of pressure amplitude. The results show that the pressure distribution in the tunnel and on the surface of the train is affected by the train speed, the length of the train and the position of the measuring point. The minimum negative peak value in the tunnel appears at the position where the superposition phenomenon is most severe, and the position will change with the speed of the train. There are two negative peak waveforms of the train surface pressure, and the first waveform is greatly affected by the train speed. It improves a reference for studying the strength requirement of the most unfavorable length tunnels and trains and ensures the safe operation of trains in tunnels of different lengths.","PeriodicalId":52804,"journal":{"name":"Transportation Safety and Environment","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42475883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yaran Yang, Lian-chuan Ma, Tao Tang, H. Ding, Zhen Liu
With the development of railway construction in China, the computing demand of train control system is increasing day by day. The application of cloud computing technology to rail transit signal system has become a research hotspot in recent years. How to improve the safety and availability of the safety computer platform in cloud computing environment is the key problem to apply cloud computing to train operation control system. As the cloud platform is in an open network environment, facing many security vulnerabilities and malicious network attacks, so it is necessary to monitor the operation of computer programs through edge safety nodes. Firstly, this paper encrypts the logical monitoring method, and then proposes a secure computer defense model based on dynamic heterogeneous redundancy structure. Then continuous time Markov chain (CTMC) is used to quantitatively solve the stable probability of the system, and the influence of different logical monitoring methods on the anti-attack performance of the system is analyzed. Finally, the experiment proves that the dynamic heterogeneous redundancy structure composed of encryption logic monitoring can guarantee the safe and stable operation of the safety computer more effectively.
{"title":"Research on Logic Monitoring Method for Cloud Computing Based Safety Computer","authors":"Yaran Yang, Lian-chuan Ma, Tao Tang, H. Ding, Zhen Liu","doi":"10.1093/tse/tdac052","DOIUrl":"https://doi.org/10.1093/tse/tdac052","url":null,"abstract":"\u0000 With the development of railway construction in China, the computing demand of train control system is increasing day by day. The application of cloud computing technology to rail transit signal system has become a research hotspot in recent years. How to improve the safety and availability of the safety computer platform in cloud computing environment is the key problem to apply cloud computing to train operation control system. As the cloud platform is in an open network environment, facing many security vulnerabilities and malicious network attacks, so it is necessary to monitor the operation of computer programs through edge safety nodes. Firstly, this paper encrypts the logical monitoring method, and then proposes a secure computer defense model based on dynamic heterogeneous redundancy structure. Then continuous time Markov chain (CTMC) is used to quantitatively solve the stable probability of the system, and the influence of different logical monitoring methods on the anti-attack performance of the system is analyzed. Finally, the experiment proves that the dynamic heterogeneous redundancy structure composed of encryption logic monitoring can guarantee the safe and stable operation of the safety computer more effectively.","PeriodicalId":52804,"journal":{"name":"Transportation Safety and Environment","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45194102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the increasing computing demand of train operation control system, the application of cloud computing technology to train control system safety computer platform has become a research hotspot in recent years. How to improve the safety and availability of private cloud safety computer is the key problem to apply cloud computing to train operation control system. Because the cloud computing platform is in an open network environment, it faces many security loopholes and malicious network attacks. Therefore, it is necessary to change the existing safety computer platform structure to improve the attack resistance of the private cloud safety computer platform, thereby enhancing its safety and reliability. Firstly, a private cloud safety computer platform architecture based on dynamic heterogeneous redundant(DHR) structure is proposed, and a dynamic migration mechanism for heterogeneous executives is designed in this paper. Then, a generalized stochastic Petri net (GSPN) model of a private cloud safety computer platform based on DHR is established, and its steady-state probability is solved by using its isomorphism with the continuous-time Markov model (CTMC). To analyze the impact of different system structures and executive migration mechanisms on the system's anti-attack performance. Finally, through the experimental verification, the system structure proposed in this paper can improve the anti-attack of the private cloud safety computer platform, thereby improving its safety and reliability.
{"title":"Research on anti-attack of private cloud safety computer based on Markov-Percopy dynamic heterogeneous redundancy structure","authors":"Jiakun Wen, Zhen Liu, H. Ding","doi":"10.1093/tse/tdac069","DOIUrl":"https://doi.org/10.1093/tse/tdac069","url":null,"abstract":"\u0000 With the increasing computing demand of train operation control system, the application of cloud computing technology to train control system safety computer platform has become a research hotspot in recent years. How to improve the safety and availability of private cloud safety computer is the key problem to apply cloud computing to train operation control system. Because the cloud computing platform is in an open network environment, it faces many security loopholes and malicious network attacks. Therefore, it is necessary to change the existing safety computer platform structure to improve the attack resistance of the private cloud safety computer platform, thereby enhancing its safety and reliability. Firstly, a private cloud safety computer platform architecture based on dynamic heterogeneous redundant(DHR) structure is proposed, and a dynamic migration mechanism for heterogeneous executives is designed in this paper. Then, a generalized stochastic Petri net (GSPN) model of a private cloud safety computer platform based on DHR is established, and its steady-state probability is solved by using its isomorphism with the continuous-time Markov model (CTMC). To analyze the impact of different system structures and executive migration mechanisms on the system's anti-attack performance. Finally, through the experimental verification, the system structure proposed in this paper can improve the anti-attack of the private cloud safety computer platform, thereby improving its safety and reliability.","PeriodicalId":52804,"journal":{"name":"Transportation Safety and Environment","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42241424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As an important transportation infrastructure and transportation backbone in China, high-speed rail (HSR) plays a critical role in promoting the development of green and low-carbon transportation. Calculating the CO2 emissions reduction performance of HSR will be conducive to promote the CO2 emissions reduction work of the railway. Based on the Dalkic HSR CO2 emissions reduction performance model, by adjusting HSR CO2 emission factor (CEFHSR), annual times of departures (T) and other parameters, this study develops China HSR CO2 emissions reduction performance model. Taking the Beijing-Shanghai HSR as the research object, this study conducts a questionnaire survey to explore the substitution effect and demand effect of HSR on different transportation modes, collects data such as passenger volume, average electricity use, and annual times of departures of Beijing-Shanghai HSR in 2019, and calculates the CO2 emissions reduction performance of the Beijing-Shanghai HSR. This study has two main results: (1) Build China HSR CO2 emissions reduction performance model based on substitution effect and demand effect. (2) In 2019, the CO2 emissions of Beijing-Shanghai HSR is 2898 233.62t, the CO2 emissions reduction performance of Beijing-Shanghai HSR is 17 999 482.8t, the annual CO2 emissions of Beijing-Shanghai line in ‘No HSR’ case is as 7.2 times as in " HSR" case, and PKT of HSR is 10.2 g/pkm. Based on the research results, this study proposes three CO2 emissions reduction policy suggestions. This study would be helpful for further HSR CO2 emissions reduction research and departments related to railway transportation management to make CO2 emissions reduction policies.
{"title":"CO2 emissions reduction Performance of China's HSR based on substitution effect and demand effect","authors":"Liying Wang, Ping Yin, Shangqing Liu","doi":"10.1093/tse/tdac060","DOIUrl":"https://doi.org/10.1093/tse/tdac060","url":null,"abstract":"\u0000 As an important transportation infrastructure and transportation backbone in China, high-speed rail (HSR) plays a critical role in promoting the development of green and low-carbon transportation. Calculating the CO2 emissions reduction performance of HSR will be conducive to promote the CO2 emissions reduction work of the railway. Based on the Dalkic HSR CO2 emissions reduction performance model, by adjusting HSR CO2 emission factor (CEFHSR), annual times of departures (T) and other parameters, this study develops China HSR CO2 emissions reduction performance model. Taking the Beijing-Shanghai HSR as the research object, this study conducts a questionnaire survey to explore the substitution effect and demand effect of HSR on different transportation modes, collects data such as passenger volume, average electricity use, and annual times of departures of Beijing-Shanghai HSR in 2019, and calculates the CO2 emissions reduction performance of the Beijing-Shanghai HSR. This study has two main results: (1) Build China HSR CO2 emissions reduction performance model based on substitution effect and demand effect. (2) In 2019, the CO2 emissions of Beijing-Shanghai HSR is 2898 233.62t, the CO2 emissions reduction performance of Beijing-Shanghai HSR is 17 999 482.8t, the annual CO2 emissions of Beijing-Shanghai line in ‘No HSR’ case is as 7.2 times as in \" HSR\" case, and PKT of HSR is 10.2 g/pkm. Based on the research results, this study proposes three CO2 emissions reduction policy suggestions. This study would be helpful for further HSR CO2 emissions reduction research and departments related to railway transportation management to make CO2 emissions reduction policies.","PeriodicalId":52804,"journal":{"name":"Transportation Safety and Environment","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41600843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the rapid development of the shipping industry, the safety and comfort of ship transportation have been paid more and more attention, and the pitch and heave motion of ships are the most serious factors. In this paper, the longitudinal motion mathematical model of YuKun is established. By assigning the zero-pole to the left half-plane and using the properties of the symmetric matrix, the shaping weighting functions matrix is designed to stabilize the Multi-Input Multi-Output (MIMO) system of YuKun. Finally, a new concise robust controller is designed using the steady output of the shaped system. The simulation results show that under the control of the concise robust controller, the pitch angle and heave of YuKun decrease by 79.9% and 86.2%. Theoretical analysis and simulation results show that the concise robust controller has a good control effect on the longitudinal motion of YuKun, and is simple and easy to use, with clear engineering significance.
{"title":"Design of concise robust control for longitudinal motion of YuKun","authors":"Chenfei Liu, Pei Xiao, Xianku Zhang, Pengqi Wang, Jiafu Wang, Dinghuo Hu","doi":"10.1093/tse/tdac063","DOIUrl":"https://doi.org/10.1093/tse/tdac063","url":null,"abstract":"\u0000 With the rapid development of the shipping industry, the safety and comfort of ship transportation have been paid more and more attention, and the pitch and heave motion of ships are the most serious factors. In this paper, the longitudinal motion mathematical model of YuKun is established. By assigning the zero-pole to the left half-plane and using the properties of the symmetric matrix, the shaping weighting functions matrix is designed to stabilize the Multi-Input Multi-Output (MIMO) system of YuKun. Finally, a new concise robust controller is designed using the steady output of the shaped system. The simulation results show that under the control of the concise robust controller, the pitch angle and heave of YuKun decrease by 79.9% and 86.2%. Theoretical analysis and simulation results show that the concise robust controller has a good control effect on the longitudinal motion of YuKun, and is simple and easy to use, with clear engineering significance.","PeriodicalId":52804,"journal":{"name":"Transportation Safety and Environment","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43870012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The coefficients of retroreflection and chromaticity coordinates are critical metrics for determining the quality of a retroreflector. However, conventional retroreflection measurement techniques rely heavily on the night-time colour, size, and characteristics of the sample being measured. This complicates the measurement process and leads to deviations in the test results. In addition, chromaticity cannot be determined using this approach. Therefore, it is necessary to improve the measurement accuracy, simplify the measurement process, and achieve the measurement of the traffic sign RA and chromaticity coordinates simultaneously. In this study, an improved method for retroreflector characterisation using imaging was proposed. This allowed for the measurement of the coefficients of retroreflection and the chromaticity coordinates simultaneously, and only a white standard sample was required for calibration. The primary components of the proposed system included a lighting projector, a receiver, two motorised rotational stages, a retroreflective sample holder, and customised software that used scaling factors to convert a digital signal into sample retroreflection coefficients and retroreflective chromaticity coordinates. The experimental results indicated that the raw data output from the camera exhibited a positive correlation relationship with the luminous flux from the surface of the retroreflector. The maximum measurement errors for the retroreflection and chromaticity were −12.2 cd/(lx·m2) and −2.09%, respectively. This method was inexpensive and convenient, used a commercially available digital camera, could help to identify defects in retroreflection and chromaticity for retroreflective sheeting, and led to increased accessibility for the quality control of retroreflective sheeting.
{"title":"Establishment of a metric to characterise retroreflector properties using a consumer-grade colour camera","authors":"Huayang He, Wenying Su, Qiutong Cheng","doi":"10.1093/tse/tdac039","DOIUrl":"https://doi.org/10.1093/tse/tdac039","url":null,"abstract":"\u0000 The coefficients of retroreflection and chromaticity coordinates are critical metrics for determining the quality of a retroreflector. However, conventional retroreflection measurement techniques rely heavily on the night-time colour, size, and characteristics of the sample being measured. This complicates the measurement process and leads to deviations in the test results. In addition, chromaticity cannot be determined using this approach. Therefore, it is necessary to improve the measurement accuracy, simplify the measurement process, and achieve the measurement of the traffic sign RA and chromaticity coordinates simultaneously. In this study, an improved method for retroreflector characterisation using imaging was proposed. This allowed for the measurement of the coefficients of retroreflection and the chromaticity coordinates simultaneously, and only a white standard sample was required for calibration. The primary components of the proposed system included a lighting projector, a receiver, two motorised rotational stages, a retroreflective sample holder, and customised software that used scaling factors to convert a digital signal into sample retroreflection coefficients and retroreflective chromaticity coordinates. The experimental results indicated that the raw data output from the camera exhibited a positive correlation relationship with the luminous flux from the surface of the retroreflector. The maximum measurement errors for the retroreflection and chromaticity were −12.2 cd/(lx·m2) and −2.09%, respectively. This method was inexpensive and convenient, used a commercially available digital camera, could help to identify defects in retroreflection and chromaticity for retroreflective sheeting, and led to increased accessibility for the quality control of retroreflective sheeting.","PeriodicalId":52804,"journal":{"name":"Transportation Safety and Environment","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46861556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Li Yu, Wang Xuhui, Yang Jie, Zhang Zemiao, Wang Chenglei, Qian Bosen, Tian Xudong, Wang Tiantian
This study investigates the airborne transmission of virus-laden droplets generated by a cough of patients in an aircraft cabin to reveal the infection risk of taking an airplane. The influence of the ventilation system on flow field of the cabin was analyzed to reveal its effects on the airborne transmission of virus-laden droplets. Meanwhile, human body heat was also considered in the simulations. The results show that hot plume due to human body heat has significant impact on the upward movement of virus-laden droplets. The virus-laden droplets expelled by a cough can be transmitted to the region with two to three rows away from the generator. Particularly, the transverse motion present in the early stage of the droplet transmission results in a high infection risk to the passengers in the same row with the patient. This work gives insight into the understanding of the airborne transmission of virus-laden droplets in the entire passenger cabin.
{"title":"Airborne transmission of virus-laden droplets in an aircraft cabin","authors":"Li Yu, Wang Xuhui, Yang Jie, Zhang Zemiao, Wang Chenglei, Qian Bosen, Tian Xudong, Wang Tiantian","doi":"10.1093/tse/tdac079","DOIUrl":"https://doi.org/10.1093/tse/tdac079","url":null,"abstract":"\u0000 This study investigates the airborne transmission of virus-laden droplets generated by a cough of patients in an aircraft cabin to reveal the infection risk of taking an airplane. The influence of the ventilation system on flow field of the cabin was analyzed to reveal its effects on the airborne transmission of virus-laden droplets. Meanwhile, human body heat was also considered in the simulations. The results show that hot plume due to human body heat has significant impact on the upward movement of virus-laden droplets. The virus-laden droplets expelled by a cough can be transmitted to the region with two to three rows away from the generator. Particularly, the transverse motion present in the early stage of the droplet transmission results in a high infection risk to the passengers in the same row with the patient. This work gives insight into the understanding of the airborne transmission of virus-laden droplets in the entire passenger cabin.","PeriodicalId":52804,"journal":{"name":"Transportation Safety and Environment","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42434862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study aims to solve path planning of intelligent vehicles in self-driving. In this study, an improved path planning method combining constraints of environment and vehicle is proposed. The algorithm designs a reasonable path cost function, then uses heuristic guided search strategy to improve the speed and quality of path planning, and finally generates smooth and continuous curvature paths based on the path post-processing method based on the requirements of path smoothness. simulation test show that compared with the basic RRT, RRT-connect and RRT* algorithms, the path length of the proposed algorithm can be reduced by 19.7%, 29.3% and 1% respectively and the maximum planned path curvature of the proposed algorithm is 0.0796 m-1 and 0.1512 m-1 respectively under the condition of a small amount of planning time. The algorithm can plan the more suitable driving path for intelligent vehicle in complex environment.
{"title":"Path Planning Algorithms for Self-Driving vehicle based on improved RRT-Connect","authors":"Li Jin, Huang Chaowei, Pan Minqiang","doi":"10.1093/tse/tdac061","DOIUrl":"https://doi.org/10.1093/tse/tdac061","url":null,"abstract":"\u0000 This study aims to solve path planning of intelligent vehicles in self-driving. In this study, an improved path planning method combining constraints of environment and vehicle is proposed. The algorithm designs a reasonable path cost function, then uses heuristic guided search strategy to improve the speed and quality of path planning, and finally generates smooth and continuous curvature paths based on the path post-processing method based on the requirements of path smoothness. simulation test show that compared with the basic RRT, RRT-connect and RRT* algorithms, the path length of the proposed algorithm can be reduced by 19.7%, 29.3% and 1% respectively and the maximum planned path curvature of the proposed algorithm is 0.0796 m-1 and 0.1512 m-1 respectively under the condition of a small amount of planning time. The algorithm can plan the more suitable driving path for intelligent vehicle in complex environment.","PeriodicalId":52804,"journal":{"name":"Transportation Safety and Environment","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46995926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Convolutional neural networks (CNNs) are widely used in the field of fault diagnosis due to their strong feature-extraction capability. However, in each timestep, CNNs only consider the current input and ignores any cyclicity in time, therefore finding difficulties in mining temporal features from the data. In this work, the third-generation neural network—spiking neural network (SNN)—is utilized in bearing fault diagnosis. SNNs incorporate temporal concepts and utilize discrete spike sequences in communication, making it more biologically explanatory. Inspired by the classic CNN LeNet-5 framework, a bearing fault diagnosis method based on a convolutional SNN is proposed. In this method, the spiking convolutional network and the spiking classifier network are constructed by using the IF and LIF model, respectively, and end-to-end training is conducted on the overall model using a surrogate gradient method. The signals are adaptively encoded into spikes in the spiking neuron layer. In addition, the network utilizes max-pooling, which is consistent with the spatial–temporal characteristics of SNNs. Combined with the spiking convolutional layers, the network fully extracts the spatial–temporal features from the bearing vibration signals. Experimental validations and comparisons are conducted on bearings. The results show that the proposed method achieves high accuracy and takes fewer time steps.
{"title":"A bearing fault diagnosis method based on a convolutional spiking neural network with spatial–temporal feature-extraction capability","authors":"Changfan Zhang, Z. Xiao, Zhenwen Sheng","doi":"10.1093/tse/tdac050","DOIUrl":"https://doi.org/10.1093/tse/tdac050","url":null,"abstract":"\u0000 Convolutional neural networks (CNNs) are widely used in the field of fault diagnosis due to their strong feature-extraction capability. However, in each timestep, CNNs only consider the current input and ignores any cyclicity in time, therefore finding difficulties in mining temporal features from the data. In this work, the third-generation neural network—spiking neural network (SNN)—is utilized in bearing fault diagnosis. SNNs incorporate temporal concepts and utilize discrete spike sequences in communication, making it more biologically explanatory. Inspired by the classic CNN LeNet-5 framework, a bearing fault diagnosis method based on a convolutional SNN is proposed. In this method, the spiking convolutional network and the spiking classifier network are constructed by using the IF and LIF model, respectively, and end-to-end training is conducted on the overall model using a surrogate gradient method. The signals are adaptively encoded into spikes in the spiking neuron layer. In addition, the network utilizes max-pooling, which is consistent with the spatial–temporal characteristics of SNNs. Combined with the spiking convolutional layers, the network fully extracts the spatial–temporal features from the bearing vibration signals. Experimental validations and comparisons are conducted on bearings. The results show that the proposed method achieves high accuracy and takes fewer time steps.","PeriodicalId":52804,"journal":{"name":"Transportation Safety and Environment","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2022-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44062724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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