This paper presents an analysis of the random fluctuations, deferred conduction effect and periodicity of road traffic based on the basic features of road networks. It also discusses the limitations of road network ev...This paper presents an analysis of the random fluctuations, deferred conduction effect and periodicity of road traffic based on the basic features of road networks. It also discusses the limitations of road network evaluation theories based on road "V/C". In addition, it proposes a set of theoretical and technical methods for the real-time evaluation of traffic flows for entire road networks, and for solving key technical issues, such as real-time data collection and processing in areas with no blind zones, the spatial-temporal dynamic analysis of road network traffic, and the calibration of key performance index thresholds. It also provides new technical tools for the strategic transportation planning and real-time diagnosis of road traffic. The new tools and methodology presented in this paper are validated using a case study in Beijing.展开更多
The objective of this paper was to develop a comprehensive evaluation method and index to evaluate the performance of sealants and fillers for cracks in asphalt concrete pavements using the method of principal compone...The objective of this paper was to develop a comprehensive evaluation method and index to evaluate the performance of sealants and fillers for cracks in asphalt concrete pavements using the method of principal component analysis. The performance experiments including cone penetration, softening point, flow, resilience and tension at low temperature respectively were conducted by reference of ASTM D5329 for eight sealants and fillers often used in China. There by a principal component model was developed and weight of every index was calculated. The experimental results show that there are significantly different performances for sealants and fillers often used in China. Principal component analysis is an objective method that evaluates and selects the performance of sealants and fillers for cracks in asphalt concrete pavements.展开更多
The CO_(2)-based combined cooling and power(CCP)system is regarded as a highly promising alternative for waste heat recovery in refrigerated trucks,owing to its environmental advantages and multienergy output.The CCP ...The CO_(2)-based combined cooling and power(CCP)system is regarded as a highly promising alternative for waste heat recovery in refrigerated trucks,owing to its environmental advantages and multienergy output.The CCP system implemented in refrigerated trucks is more intricate than conventional waste heat recovery systems.It not only produces energy to satisfy demand via waste heat recovery but also incorporates refrigeration capabilities,substituting the standalone refrigeration unit to sustain low temperatures in refrigerated trucks.This coupling of power and refrigeration subcycles significantly increases the complexity of system control and the requirements for stability.Current research primarily focuses on the steady-state performance of CCP systems,neglecting the impact of load variations on the system’s dynamic response in real operating conditions,thereby limiting a comprehensive assessment of operational performance under complex scenarios.This study proposes a hybrid control strategy based on deep deterministic policy gradient deep reinforcement learning and conducts dynamic simulations to comprehensively evaluate the energy efficiency performance of the CCP system.The results show that under the China Heavy-Duty Commercial Vehicle Test Cycle conditions,this strategy reduces fuel consumption by 6.63%per 100 km while ensuring that the CCP system remains within safety constraints throughout the entire operation.These findings provide important insights for the application of CCP systems in the cold chain transportation sector.展开更多
基金"973"National Key Basic Research & Development Program "Research of the Basic Scientific Issues in the Traffic Congestion Bottlenecks of Big Cities"( No. 2006CB705500)Beijing Science & Technology Program "Research of the New Data Collection Technologies for Transportation Management " (No.D101100049710004)Beijing Science & Technology Program "Research of the Demonstration Platform for the In-tegrated Dynamic Operation Analysis of City Road Networks"(No. D07050600440704)
文摘This paper presents an analysis of the random fluctuations, deferred conduction effect and periodicity of road traffic based on the basic features of road networks. It also discusses the limitations of road network evaluation theories based on road "V/C". In addition, it proposes a set of theoretical and technical methods for the real-time evaluation of traffic flows for entire road networks, and for solving key technical issues, such as real-time data collection and processing in areas with no blind zones, the spatial-temporal dynamic analysis of road network traffic, and the calibration of key performance index thresholds. It also provides new technical tools for the strategic transportation planning and real-time diagnosis of road traffic. The new tools and methodology presented in this paper are validated using a case study in Beijing.
基金Funded by the National Natural Science Foundation of China(Nos.51408287 and 51668038)the Rolls Supported by Program for Changjiang Scholars and Innovative Research Team in University(IRT_15R29)+2 种基金the Distinguished Young Scholars Fund of Gansu Province(1606RJDA318)the Natural Science Foundation of Gansu Province(1506RJZA064)the Excellent Program of Lanzhou Jiaotong University(201606)
文摘The objective of this paper was to develop a comprehensive evaluation method and index to evaluate the performance of sealants and fillers for cracks in asphalt concrete pavements using the method of principal component analysis. The performance experiments including cone penetration, softening point, flow, resilience and tension at low temperature respectively were conducted by reference of ASTM D5329 for eight sealants and fillers often used in China. There by a principal component model was developed and weight of every index was calculated. The experimental results show that there are significantly different performances for sealants and fillers often used in China. Principal component analysis is an objective method that evaluates and selects the performance of sealants and fillers for cracks in asphalt concrete pavements.
基金Guangxi Science and Technol-ogy Major Program(AA24206013)the National Science Found for Excellent Young Scholars(No.52022066)+1 种基金the Youth Innovation Pro-motion Association of Chinese Academy of Sciences(Grant No 2022463)the Research Center for Multi-Energy Complementation and Conversion.
文摘The CO_(2)-based combined cooling and power(CCP)system is regarded as a highly promising alternative for waste heat recovery in refrigerated trucks,owing to its environmental advantages and multienergy output.The CCP system implemented in refrigerated trucks is more intricate than conventional waste heat recovery systems.It not only produces energy to satisfy demand via waste heat recovery but also incorporates refrigeration capabilities,substituting the standalone refrigeration unit to sustain low temperatures in refrigerated trucks.This coupling of power and refrigeration subcycles significantly increases the complexity of system control and the requirements for stability.Current research primarily focuses on the steady-state performance of CCP systems,neglecting the impact of load variations on the system’s dynamic response in real operating conditions,thereby limiting a comprehensive assessment of operational performance under complex scenarios.This study proposes a hybrid control strategy based on deep deterministic policy gradient deep reinforcement learning and conducts dynamic simulations to comprehensively evaluate the energy efficiency performance of the CCP system.The results show that under the China Heavy-Duty Commercial Vehicle Test Cycle conditions,this strategy reduces fuel consumption by 6.63%per 100 km while ensuring that the CCP system remains within safety constraints throughout the entire operation.These findings provide important insights for the application of CCP systems in the cold chain transportation sector.
