With the deepening of the“Belt and Road”initiative,Chinese enterprises are facing unprecedented opportunities and challenges for international cooperation.This paper mainly analyzes the current situation,existing pr...With the deepening of the“Belt and Road”initiative,Chinese enterprises are facing unprecedented opportunities and challenges for international cooperation.This paper mainly analyzes the current situation,existing problems,and coping strategies of enterprise international cooperation management in the context of the“Belt and Road”.This article expounds on the importance of the“Belt and Road”initiative for international cooperation of enterprises and analyzes the key links of international cooperation management of enterprises from the aspects of internationalization strategy,cross-cultural management,risk prevention and control,and resource integration.Finally,combined with the case,this paper puts forward the management strategies and suggestions that enterprises should adopt in international cooperation,to provide a useful reference for Chinese enterprises in international cooperation in the construction of the“Belt and Road.”展开更多
Control signaling is mandatory for the operation and management of all types of communication networks,including the Third Generation Partnership Project(3GPP)mobile broadband networks.However,they consume important a...Control signaling is mandatory for the operation and management of all types of communication networks,including the Third Generation Partnership Project(3GPP)mobile broadband networks.However,they consume important and scarce network resources such as bandwidth and processing power.There have been several reports of these control signaling turning into signaling storms halting network operations and causing the respective Telecom companies big financial losses.This paper draws its motivation from such real network disaster incidents attributed to signaling storms.In this paper,we present a thorough survey of the causes,of the signaling storm problems in 3GPP-based mobile broadband networks and discuss in detail their possible solutions and countermeasures.We provide relevant analytical models to help quantify the effect of the potential causes and benefits of their corresponding solutions.Another important contribution of this paper is the comparison of the possible causes and solutions/countermeasures,concerning their effect on several important network aspects such as architecture,additional signaling,fidelity,etc.,in the form of a table.This paper presents an update and an extension of our earlier conference publication.To our knowledge,no similar survey study exists on the subject.展开更多
The post-earthquake emergency period,which is a sensitive time segment just after an event,mainly focuses on saving life and restoring social order.To improve the seismic resilience of city road networks,a resilience ...The post-earthquake emergency period,which is a sensitive time segment just after an event,mainly focuses on saving life and restoring social order.To improve the seismic resilience of city road networks,a resilience evaluation method used in the post-earthquake emergency period is proposed.The road seismic damage index of a city road network can consider the influence of roads,bridges and buildings along the roads,etc.on road capacity after an earthquake.A function index for a city road network is developed,which reflects the connectivity,redundancy,traffic demand and traffic function of the network.An optimization model for improving the road repair order in the post-earthquake emergency period is also developed according to the resilience evaluation,to enable decision support for city emergency management and achieve the best seismic resilience of the city road network.The optimization model is applied to a city road network and the results illustrate the feasibility of the resilience evaluation and optimization method for a city road network in the post-earthquake emergency period.展开更多
The Heinenoord Tunnel in The Netherlands connects the Hoeksche Waard Island with the city of Rotterdam.The tunnel is 614 m long,consists of two unidirectional tubes(3 lanes each)and has an average daily traffic load o...The Heinenoord Tunnel in The Netherlands connects the Hoeksche Waard Island with the city of Rotterdam.The tunnel is 614 m long,consists of two unidirectional tubes(3 lanes each)and has an average daily traffic load of 92,100 vehicles.The tunnel was opened for traffic in 1969.The structure is basically still sound,but a full refurbishment of the installations and systems is required,because they are end of life.A long closure of the tunnel(or even one tube)is not possible,because alternative routes are scarce and require significant extra travel time,not suitable for the high traffic load.Thus,various scenarios were considered to assure the accessibility of the Hoeksche Waard during the works,scheduled for 2023-2024.Multi-criteria analyses were performed for each scenario,taking into account the total project cost,societal cost(due to extra travel time)and the total required time span for the works.Refurbishment through“parallel assembly”proved to be optimal.This concept means that the new installations and systems are installed next to the current ones,that will remain in service until the end phase of the refurbishment.The existing installations and systems are only dismantled after integral testing has shown that the completed new ones work properly.This approach allows most of the works to be carried out during a series of night and weekend closures of just one tube.This limits nuisance,because one driving direction is always left undisturbed,while the closure for the other driving direction takes place in low-traffic periods.This paper describes the applied method to select the optimal refurbishment approach,as well as the(partly unconventional)measures that are implemented to enhance the resilience of the tunnel system to assure as much availability for traffic as possible,also during future maintenance works.展开更多
The development of the national economy is closely tied to infrastructure construction.In recent years,China has seen a significant increase in the number and scale of road construction projects,aimed at facilitating ...The development of the national economy is closely tied to infrastructure construction.In recent years,China has seen a significant increase in the number and scale of road construction projects,aimed at facilitating the flow of goods and enabling convenient travel for the masses.However,this surge in road construction also raises concerns about road traffic safety.Road traffic safety facilities play a crucial role in warning and protecting against traffic accidents.To ensure their effective implementation,this paper analyzes the essence of road traffic facilities and their impact on traffic safety.By identifying challenges in the application of traffic safety facilities and adhering to safety facility application principles,suggestions are proposed to enhance traffic safety management.展开更多
The air traffic management system(ATM)has the task of ensuring safe,orderly and expeditious flow of air traffic.The ATM system architecture is very much dependent on the concept of operations(ConOps).Over the years th...The air traffic management system(ATM)has the task of ensuring safe,orderly and expeditious flow of air traffic.The ATM system architecture is very much dependent on the concept of operations(ConOps).Over the years the evolution in ConOps has resulted in changes in the ATM′s physical architecture,improving its physical infrastructure,increasing the levels of automation and making operational changes to improve air traffic flow,to cope with increasing demand for air travel.However,what is less clear is the impact of such changes in ConOps on the ATM′s functional architecture.This is vital for ensuring optimality in the implementation of the physical architecture components to support the ATM functions.This paper reviews the changes in the ConOps over the years,proposes a temporally invariant ATM functional model,and discusses some of the main key technologies expected to make significant improvements to the ATM system.展开更多
The Single European Sky Air Traffic management(ATM)Research(SESAR)project is the technological pillar of the European Commission’s Single European Sky Initiative to modernize ATM.Here,we describe the process of estab...The Single European Sky Air Traffic management(ATM)Research(SESAR)project is the technological pillar of the European Commission’s Single European Sky Initiative to modernize ATM.Here,we describe the process of establishing SESAR and the main parts of the project:the research and development(R&D)part,which is led by the SESAR Joint Undertaking;the deployment part,which is managed by the SESAR Deployment Manager;and the European ATM Master Plan,which collects and lays out both the R&D and deployment needs.The latest European ATM Master Plan was adopted just prior to the current pandemic.The huge loss in air traffic due to the pandemic,and the speed of the recovery of the aviation industry will require reprioritization,but the main elements that have been established-particularly those in support of the environment-remain valid.展开更多
This study aims to evaluate measures against the Urban Heat Island (UHI) regarding artificial exhaust heat of road traffic using Geographic Information Systems (GIS) in the Tokyo Ward Area where the degree of UHI is p...This study aims to evaluate measures against the Urban Heat Island (UHI) regarding artificial exhaust heat of road traffic using Geographic Information Systems (GIS) in the Tokyo Ward Area where the degree of UHI is particularly strong. We developed a GIS database that reflected road traffic conditions, and calculated the volume of artificial exhaust heat of road traffic to evaluate measures against the UHI. The findings of this study can be summarized in the following three points. 1) Artificial exhaust heat volume for moving targets was remarkably higher than that of stationary targets and, in particular, artificial exhaust heat volume was high on roads with remarkable numbers of vehicles and running speeds such as expressways and ring roads. 2) In UHI- related policy for moving targets, the suppression of waste heat through choice of fuel burned, improvement of traffic flow by securing space for cyclists and pedestrians, development of bypasses, and upgrading signal control managed to reduce artificial exhaust heat volume, even though there were differences in degree of reduction. 3) In UHI-related policy for stationary targets, special road surfaces and the increase in efficiency of energy consumption equipment achieved a reduction ratio of around 30% in artificial exhaust heat volume, more than moving targets as well as making it possible to expect a reduction in artificial exhaust heat volume on a wide scale.展开更多
Traffic management is an important contribution in the sustainable development of urban traffic.The complexity of traffic problems determines the difficulty of traffic management.Therefore,traffic management needs the...Traffic management is an important contribution in the sustainable development of urban traffic.The complexity of traffic problems determines the difficulty of traffic management.Therefore,traffic management needs the guidance of scientific theories.This paper explores traffic management systems engineering for management road traffic.First,the paper looks at the contents of road traffic management from a systems perspective.Second,the paper briefly describes systems engineering,and explains the necessity and feasibility of the combination of the traffic management and systems engineering.At last,the paper puts forward the concept of traffic management systems engineering using a systems framework.展开更多
With the development of the social economy,the traditional transportation mode will be replaced by the new mode which emphasizes the integration and cooperation between the transportation modes.The advent of automobil...With the development of the social economy,the traditional transportation mode will be replaced by the new mode which emphasizes the integration and cooperation between the transportation modes.The advent of automobilization in China has further intensified the pressure of the road traffic.The traffic jam alarm caused by the traffic accidents is increasing year by year.The minor accidents that can be dealt with quickly account for more than 70%of the traffic accidents.Traditionally,when dealing with the minor accidents,car owners often choose to stay on the spot and wait for the traffic police to deal with them.It is easy to cause"minor accidents and big traffic jams",which lead to the congestion of a road,a bridge and even a block.展开更多
This study mainly analyzed problems in ecological landscape and traffic safety of urban roads, and in view of these problems, proposed the design concepts, principles and focuses of urban road eco-landscape ensuring t...This study mainly analyzed problems in ecological landscape and traffic safety of urban roads, and in view of these problems, proposed the design concepts, principles and focuses of urban road eco-landscape ensuring traffic safety.展开更多
The air traffic management(ATM)system is an intelligent system,which integrates the ground computer network,airborne network and space satellite(communication and navigation)network by the ground-air data link system....The air traffic management(ATM)system is an intelligent system,which integrates the ground computer network,airborne network and space satellite(communication and navigation)network by the ground-air data link system.Due to the openness and widely distribution of ATM system,the trust relationship of all parties in the system is pretty complex.At present,public key infrastructure(PKI)based identity authentication method is more and more difficult to meet the growing demand of ATM service.First,through the analysis of the organizational structure and operation mode of ATM system,this paper points out the existing identity authentication security threats in ATM system,and discusses the advantages of adopting blockchain technology in ATM system.Further,we briefly analyze some shortcomings of the current PKI-based authentication system in ATM.Particularly,to address the authentication problem,this paper proposes and presents a trusted ATM Security Authentication Model and authentication protocol based on blockchain.Finally,this paper makes a comprehensive analysis and simulation of the proposed security authentication scheme,and gets the expected effect.展开更多
Traffic intersections are incredibly dangerous for drivers and pedestrians. Statistics from both Canada and the U.S. show a high number of fatalities and serious injuries related to crashes at intersections. In Canada...Traffic intersections are incredibly dangerous for drivers and pedestrians. Statistics from both Canada and the U.S. show a high number of fatalities and serious injuries related to crashes at intersections. In Canada, during 2019, the National Collision Database shows that 28% of traffic fatalities and 42% of serious injuries occurred at intersections. Likewise, the U.S. National Highway Traffic Administration (NHTSA) found that about 40% of the estimated 5,811,000 accidents in the U.S. during the year studied were intersection-related crashes. In fact, a major survey by the car insurance industry found that nearly 85% of drivers could not identify the correct action to take when approaching a yellow traffic light at an intersection. One major reason for these accidents is the “yellow light dilemma,” the ambiguous situation where a driver should stop or proceed forward when unexpectedly faced with a yellow light. This situation is even further exacerbated by the tendency of aggressive drivers to inappropriately speed up on the yellow just to get through the traffic light. A survey of Canadian drivers conducted by the Traffic Injury Research Foundation found that 9% of drivers admitted to speeding up to get through a traffic light. Another reason for these accidents is the increased danger of making a left-hand turn on yellow. According to the National Highway Traffic Safety Association (NHTSA), left turns occur in approximately 22.2% of collisions—as opposed to just 1.2% for right turns. Moreover, a study by CNN found left turns are three times as likely to kill pedestrians than right turns. The reason left turns are so much more likely to cause an accident is because they take a driver against traffic and in the path of oncoming cars. Additionally, most of these left turns occur at the driver’s discretion—as opposed to the distressingly brief left-hand arrow at busy intersections. Drive Safe Now proposes a workable solution for reducing the number of accidents occurring during a yellow light at intersections. We believe this fairly simple solution will save lives, prevent injuries, reduce damage to public and private property, and decrease insurance costs.展开更多
The macro modeling and the solution of traffic flow with road width were investigated.Firstly,a new macro model with the consideration of road width was proposed.Secondly,the effects of road width on uniform flow and ...The macro modeling and the solution of traffic flow with road width were investigated.Firstly,a new macro model with the consideration of road width was proposed.Secondly,the effects of road width on uniform flow and small perturbation were studied.The analytical and numerical results show that widening (shrinking) road can enhance (reduce) the equilibrium speed and flow,and the increments (decrements) will increase with the absolute value of road width gradient.In addition,the numerical results illustrate that the new model can describe the effects of road width on the evolutions of uniform flow and small perturbation.展开更多
Road traffic congestion can inevitably de-grade road infrastructure and decrease travel efficiency in urban traffic networks,which can be relieved by employing appropriate congestion control.Accord-ing to different de...Road traffic congestion can inevitably de-grade road infrastructure and decrease travel efficiency in urban traffic networks,which can be relieved by employing appropriate congestion control.Accord-ing to different developmental driving forces,in this paper,the evolution of road traffic congestion control is divided into two stages.The ever-growing num-ber of advanced sensing techniques can be seen as the key driving force of the first stage,called the sens-ing stage,in which congestion control strategies ex-perienced rapid growth owing to the accessibility of traffic data.At the second stage,i.e.,the communica-tion stage,communication and computation capabil-ity can be regarded as the identifying symbols for this stage,where the ability of collecting finer-grained in-sight into transportation and mobility reality improves dramatically with advances in vehicular networks,Big Data,and artificial intelligence.Specifically,as the pre-requisite for congestion control,in this paper,ex-isting congestion detection techniques are first elab-orated and classified.Then,a comprehensive survey of the recent advances for current congestion control strategies with a focus on traffic signal control,vehi-cle route guidance,and their combined techniques is provided.In this regard,the evolution of these strate-gies with continuous development of sensing,com-munication,and computation capability are also intro-duced.Finally,the paper concludes with several re-search challenges and trends to fully promote the in-tegration of advanced techniques for traffic congestion mitigation in transportation systems.展开更多
A good acoustic environment is absolutely essential to maintaining a high level satisfaction and moral health among residents. Noise and other boresome sounds come from both in- door and outdoor sources. For the resid...A good acoustic environment is absolutely essential to maintaining a high level satisfaction and moral health among residents. Noise and other boresome sounds come from both in- door and outdoor sources. For the residential buildings adjacent to heavy traffic roads, outdoors traffic noise is the main source that affects indoor acoustic quality and health. Ventilation and outdoor noise prevention become a pair of contradictions for the residents in China nowadays for those buildings adjacent to heavy traffic roads. It is investigated that traffic noise emission is mainly con- stituted by the motors of trucks, buses and motorcycles as well as brake. In this paper, two methods of traffic noise reduction on the indoor sound environment and comfort are carried out to study and compare the residential buildings adjacent to heavy traffic roadway in a city. One is to install noise barriers on the two sides of the roadway, which consist of sound-proof glass and plas- tic materials. The effect of sound-insulation of this method is heavily dependent on the relative distance between the noise bar- rier and indoors. A reduction of sound with an average pressure level of 2–15dB is achieved on the places behind and under the noise barrier. However, for the equivalent of noise barrier height, the noise reduction effect is little. As for the places of higher than the noise barrier, the traffic noise will be even strengthened by 3–7dB. Noise increment can be seen at the points of distance farther than 15m and height more than noise barrier; the noise reduction effect is not satisfactory or even worsened. In addition, not every location is appropriate to install the noise barrier along the heavy traffic roads. The other method of noise reduction for the buildings adjacent to heavy traffic is to install the airproof and soundproof windows, which is the conversion from natural venti- lation to mechanical ventilation. A reduction of sound with an average pressure level of 5dB to 17dB can be achieved compared with common glass windows, if adopting sound proof glass win- dows. These two methods are helpful to isolate high frequency noise but not for low frequency noise. For those frequency noises, installing thick and cotton curtain and porous carpet can only decrease 2.4–4.5dB, which hardly contributes to indoor sound comfort, so further study is demanded to cut down traffic noise, especially to cut down the low frequency noise.展开更多
An understanding of the influence of contractor monitoring on performance of road infrastructural projects in Uganda provided an impetus for this study. The objectives of the study were to: assess the relationship bet...An understanding of the influence of contractor monitoring on performance of road infrastructural projects in Uganda provided an impetus for this study. The objectives of the study were to: assess the relationship between contractors monitoring and performance of national road infrastructure projects and the relationship between contractor monitoring components and performance of national road infrastructure projects in Uganda. Purposive sampling was employed in selecting the procurement professionals, engineers and simple random sampling was adopted in selecting private consultants, members of parliament and respondents from the civil society organizations. Data for this study were collected using a closed ended questionnaire and interviews. Some of the major finding from this study include: weak procurement rules which lead to awarding road projects to incompetent contractors;contractor monitoring being handled by unqualified, incompetent and inexperienced professionals;lack of contractors and contract supervisors appraisal system;delay of contractors payments which affects timelines in services delivery;lack of a strong internal project monitoring and evaluation mechanism at the Uganda National Roads Agency (UNRA). The research therefore recommends the establishment of an Independent Public Infrastructure Development and Monitoring Unit by government and adoption of systems that appraise both contractors and contract supervisors with clear disciplinary actions for unsatisfactory performance by the UNRA.展开更多
Vehicle emissions calculation methods mostly use ownership information or annual road monitoring data as the activity level to calculate air pollutant emissions,but it is hard to reflect either the emissions intensity...Vehicle emissions calculation methods mostly use ownership information or annual road monitoring data as the activity level to calculate air pollutant emissions,but it is hard to reflect either the emissions intensity under different conditions or the spatiotemporal characteristics in various sections based on such approaches.This paper presents a method based on the Macroscopic Fundamental Diagram and real-time traffic data to calculate vehicle emissions,which could reflect the operation conditions and emission characteristics of vehicles.Following the‘Technical Guide for the Compiling of Road Vehicle Air Pollutant Emissions Inventories’,the emissions of three roads with different lane numbers and road grades in Beijing were estimated and verified using this method.Compared with monitoring data,the average deviations of the traffic flow on the Fifth Expressway,Jingfu National Highway,and Jingzhou Provincial Highway were?25.5%,?26.5%,and?13.4%,respectively,and the average deviations of nitrogen oxides emissions were?27.7%,?12.9%,and?12%,respectively.This method showed good application potentials to construct the emissions inventory applied to the block-scale model and analyze the spatiotemporal distribution characteristics of motor vehicle emissions in urban areas.展开更多
Wind speed,temperature,relative humidity and TSP concentration at three intersections in Binzhou City were monitored,and the relationships of TSP concentration with wind speed,temperature,relative humidity and traffic...Wind speed,temperature,relative humidity and TSP concentration at three intersections in Binzhou City were monitored,and the relationships of TSP concentration with wind speed,temperature,relative humidity and traffic flow at the three intersections in Binzhou City were analyzed by using SPSS.The results show that traffic flow was the main factor affecting TSP concentration of road traffic in Binzhou City.展开更多
文摘With the deepening of the“Belt and Road”initiative,Chinese enterprises are facing unprecedented opportunities and challenges for international cooperation.This paper mainly analyzes the current situation,existing problems,and coping strategies of enterprise international cooperation management in the context of the“Belt and Road”.This article expounds on the importance of the“Belt and Road”initiative for international cooperation of enterprises and analyzes the key links of international cooperation management of enterprises from the aspects of internationalization strategy,cross-cultural management,risk prevention and control,and resource integration.Finally,combined with the case,this paper puts forward the management strategies and suggestions that enterprises should adopt in international cooperation,to provide a useful reference for Chinese enterprises in international cooperation in the construction of the“Belt and Road.”
基金the Deanship of Graduate Studies and Scientific Research at Qassim University for financial support(QU-APC-2024-9/1).
文摘Control signaling is mandatory for the operation and management of all types of communication networks,including the Third Generation Partnership Project(3GPP)mobile broadband networks.However,they consume important and scarce network resources such as bandwidth and processing power.There have been several reports of these control signaling turning into signaling storms halting network operations and causing the respective Telecom companies big financial losses.This paper draws its motivation from such real network disaster incidents attributed to signaling storms.In this paper,we present a thorough survey of the causes,of the signaling storm problems in 3GPP-based mobile broadband networks and discuss in detail their possible solutions and countermeasures.We provide relevant analytical models to help quantify the effect of the potential causes and benefits of their corresponding solutions.Another important contribution of this paper is the comparison of the possible causes and solutions/countermeasures,concerning their effect on several important network aspects such as architecture,additional signaling,fidelity,etc.,in the form of a table.This paper presents an update and an extension of our earlier conference publication.To our knowledge,no similar survey study exists on the subject.
基金National Natural Science Foundation of China under Grant Nos.U1939210 and 51825801。
文摘The post-earthquake emergency period,which is a sensitive time segment just after an event,mainly focuses on saving life and restoring social order.To improve the seismic resilience of city road networks,a resilience evaluation method used in the post-earthquake emergency period is proposed.The road seismic damage index of a city road network can consider the influence of roads,bridges and buildings along the roads,etc.on road capacity after an earthquake.A function index for a city road network is developed,which reflects the connectivity,redundancy,traffic demand and traffic function of the network.An optimization model for improving the road repair order in the post-earthquake emergency period is also developed according to the resilience evaluation,to enable decision support for city emergency management and achieve the best seismic resilience of the city road network.The optimization model is applied to a city road network and the results illustrate the feasibility of the resilience evaluation and optimization method for a city road network in the post-earthquake emergency period.
文摘The Heinenoord Tunnel in The Netherlands connects the Hoeksche Waard Island with the city of Rotterdam.The tunnel is 614 m long,consists of two unidirectional tubes(3 lanes each)and has an average daily traffic load of 92,100 vehicles.The tunnel was opened for traffic in 1969.The structure is basically still sound,but a full refurbishment of the installations and systems is required,because they are end of life.A long closure of the tunnel(or even one tube)is not possible,because alternative routes are scarce and require significant extra travel time,not suitable for the high traffic load.Thus,various scenarios were considered to assure the accessibility of the Hoeksche Waard during the works,scheduled for 2023-2024.Multi-criteria analyses were performed for each scenario,taking into account the total project cost,societal cost(due to extra travel time)and the total required time span for the works.Refurbishment through“parallel assembly”proved to be optimal.This concept means that the new installations and systems are installed next to the current ones,that will remain in service until the end phase of the refurbishment.The existing installations and systems are only dismantled after integral testing has shown that the completed new ones work properly.This approach allows most of the works to be carried out during a series of night and weekend closures of just one tube.This limits nuisance,because one driving direction is always left undisturbed,while the closure for the other driving direction takes place in low-traffic periods.This paper describes the applied method to select the optimal refurbishment approach,as well as the(partly unconventional)measures that are implemented to enhance the resilience of the tunnel system to assure as much availability for traffic as possible,also during future maintenance works.
文摘The development of the national economy is closely tied to infrastructure construction.In recent years,China has seen a significant increase in the number and scale of road construction projects,aimed at facilitating the flow of goods and enabling convenient travel for the masses.However,this surge in road construction also raises concerns about road traffic safety.Road traffic safety facilities play a crucial role in warning and protecting against traffic accidents.To ensure their effective implementation,this paper analyzes the essence of road traffic facilities and their impact on traffic safety.By identifying challenges in the application of traffic safety facilities and adhering to safety facility application principles,suggestions are proposed to enhance traffic safety management.
文摘The air traffic management system(ATM)has the task of ensuring safe,orderly and expeditious flow of air traffic.The ATM system architecture is very much dependent on the concept of operations(ConOps).Over the years the evolution in ConOps has resulted in changes in the ATM′s physical architecture,improving its physical infrastructure,increasing the levels of automation and making operational changes to improve air traffic flow,to cope with increasing demand for air travel.However,what is less clear is the impact of such changes in ConOps on the ATM′s functional architecture.This is vital for ensuring optimality in the implementation of the physical architecture components to support the ATM functions.This paper reviews the changes in the ConOps over the years,proposes a temporally invariant ATM functional model,and discusses some of the main key technologies expected to make significant improvements to the ATM system.
文摘The Single European Sky Air Traffic management(ATM)Research(SESAR)project is the technological pillar of the European Commission’s Single European Sky Initiative to modernize ATM.Here,we describe the process of establishing SESAR and the main parts of the project:the research and development(R&D)part,which is led by the SESAR Joint Undertaking;the deployment part,which is managed by the SESAR Deployment Manager;and the European ATM Master Plan,which collects and lays out both the R&D and deployment needs.The latest European ATM Master Plan was adopted just prior to the current pandemic.The huge loss in air traffic due to the pandemic,and the speed of the recovery of the aviation industry will require reprioritization,but the main elements that have been established-particularly those in support of the environment-remain valid.
文摘This study aims to evaluate measures against the Urban Heat Island (UHI) regarding artificial exhaust heat of road traffic using Geographic Information Systems (GIS) in the Tokyo Ward Area where the degree of UHI is particularly strong. We developed a GIS database that reflected road traffic conditions, and calculated the volume of artificial exhaust heat of road traffic to evaluate measures against the UHI. The findings of this study can be summarized in the following three points. 1) Artificial exhaust heat volume for moving targets was remarkably higher than that of stationary targets and, in particular, artificial exhaust heat volume was high on roads with remarkable numbers of vehicles and running speeds such as expressways and ring roads. 2) In UHI- related policy for moving targets, the suppression of waste heat through choice of fuel burned, improvement of traffic flow by securing space for cyclists and pedestrians, development of bypasses, and upgrading signal control managed to reduce artificial exhaust heat volume, even though there were differences in degree of reduction. 3) In UHI-related policy for stationary targets, special road surfaces and the increase in efficiency of energy consumption equipment achieved a reduction ratio of around 30% in artificial exhaust heat volume, more than moving targets as well as making it possible to expect a reduction in artificial exhaust heat volume on a wide scale.
文摘Traffic management is an important contribution in the sustainable development of urban traffic.The complexity of traffic problems determines the difficulty of traffic management.Therefore,traffic management needs the guidance of scientific theories.This paper explores traffic management systems engineering for management road traffic.First,the paper looks at the contents of road traffic management from a systems perspective.Second,the paper briefly describes systems engineering,and explains the necessity and feasibility of the combination of the traffic management and systems engineering.At last,the paper puts forward the concept of traffic management systems engineering using a systems framework.
文摘With the development of the social economy,the traditional transportation mode will be replaced by the new mode which emphasizes the integration and cooperation between the transportation modes.The advent of automobilization in China has further intensified the pressure of the road traffic.The traffic jam alarm caused by the traffic accidents is increasing year by year.The minor accidents that can be dealt with quickly account for more than 70%of the traffic accidents.Traditionally,when dealing with the minor accidents,car owners often choose to stay on the spot and wait for the traffic police to deal with them.It is easy to cause"minor accidents and big traffic jams",which lead to the congestion of a road,a bridge and even a block.
文摘This study mainly analyzed problems in ecological landscape and traffic safety of urban roads, and in view of these problems, proposed the design concepts, principles and focuses of urban road eco-landscape ensuring traffic safety.
基金This work was supported in part by the National Key R&D Program of China(No.2022YFB3904503)National Natural Science Foundation of China(No.62172418).
文摘The air traffic management(ATM)system is an intelligent system,which integrates the ground computer network,airborne network and space satellite(communication and navigation)network by the ground-air data link system.Due to the openness and widely distribution of ATM system,the trust relationship of all parties in the system is pretty complex.At present,public key infrastructure(PKI)based identity authentication method is more and more difficult to meet the growing demand of ATM service.First,through the analysis of the organizational structure and operation mode of ATM system,this paper points out the existing identity authentication security threats in ATM system,and discusses the advantages of adopting blockchain technology in ATM system.Further,we briefly analyze some shortcomings of the current PKI-based authentication system in ATM.Particularly,to address the authentication problem,this paper proposes and presents a trusted ATM Security Authentication Model and authentication protocol based on blockchain.Finally,this paper makes a comprehensive analysis and simulation of the proposed security authentication scheme,and gets the expected effect.
文摘Traffic intersections are incredibly dangerous for drivers and pedestrians. Statistics from both Canada and the U.S. show a high number of fatalities and serious injuries related to crashes at intersections. In Canada, during 2019, the National Collision Database shows that 28% of traffic fatalities and 42% of serious injuries occurred at intersections. Likewise, the U.S. National Highway Traffic Administration (NHTSA) found that about 40% of the estimated 5,811,000 accidents in the U.S. during the year studied were intersection-related crashes. In fact, a major survey by the car insurance industry found that nearly 85% of drivers could not identify the correct action to take when approaching a yellow traffic light at an intersection. One major reason for these accidents is the “yellow light dilemma,” the ambiguous situation where a driver should stop or proceed forward when unexpectedly faced with a yellow light. This situation is even further exacerbated by the tendency of aggressive drivers to inappropriately speed up on the yellow just to get through the traffic light. A survey of Canadian drivers conducted by the Traffic Injury Research Foundation found that 9% of drivers admitted to speeding up to get through a traffic light. Another reason for these accidents is the increased danger of making a left-hand turn on yellow. According to the National Highway Traffic Safety Association (NHTSA), left turns occur in approximately 22.2% of collisions—as opposed to just 1.2% for right turns. Moreover, a study by CNN found left turns are three times as likely to kill pedestrians than right turns. The reason left turns are so much more likely to cause an accident is because they take a driver against traffic and in the path of oncoming cars. Additionally, most of these left turns occur at the driver’s discretion—as opposed to the distressingly brief left-hand arrow at busy intersections. Drive Safe Now proposes a workable solution for reducing the number of accidents occurring during a yellow light at intersections. We believe this fairly simple solution will save lives, prevent injuries, reduce damage to public and private property, and decrease insurance costs.
基金Project(NCET-08-0038) supported by the Program for New Century Excellent Talents in Chinese UniversityProjects(70701002,70971007 and 70521001) supported by the National Natural Science Foundation of ChinaProject(2006CB705503) supported by the National Basic Research Program of China
文摘The macro modeling and the solution of traffic flow with road width were investigated.Firstly,a new macro model with the consideration of road width was proposed.Secondly,the effects of road width on uniform flow and small perturbation were studied.The analytical and numerical results show that widening (shrinking) road can enhance (reduce) the equilibrium speed and flow,and the increments (decrements) will increase with the absolute value of road width gradient.In addition,the numerical results illustrate that the new model can describe the effects of road width on the evolutions of uniform flow and small perturbation.
基金the National Key R&D Program of China(2019YFB1600100)National Nat-ural Science Foundation of China(U1801266)the Youth Innovation Team of Shaanxi Universities.
文摘Road traffic congestion can inevitably de-grade road infrastructure and decrease travel efficiency in urban traffic networks,which can be relieved by employing appropriate congestion control.Accord-ing to different developmental driving forces,in this paper,the evolution of road traffic congestion control is divided into two stages.The ever-growing num-ber of advanced sensing techniques can be seen as the key driving force of the first stage,called the sens-ing stage,in which congestion control strategies ex-perienced rapid growth owing to the accessibility of traffic data.At the second stage,i.e.,the communica-tion stage,communication and computation capabil-ity can be regarded as the identifying symbols for this stage,where the ability of collecting finer-grained in-sight into transportation and mobility reality improves dramatically with advances in vehicular networks,Big Data,and artificial intelligence.Specifically,as the pre-requisite for congestion control,in this paper,ex-isting congestion detection techniques are first elab-orated and classified.Then,a comprehensive survey of the recent advances for current congestion control strategies with a focus on traffic signal control,vehi-cle route guidance,and their combined techniques is provided.In this regard,the evolution of these strate-gies with continuous development of sensing,com-munication,and computation capability are also intro-duced.Finally,the paper concludes with several re-search challenges and trends to fully promote the in-tegration of advanced techniques for traffic congestion mitigation in transportation systems.
文摘A good acoustic environment is absolutely essential to maintaining a high level satisfaction and moral health among residents. Noise and other boresome sounds come from both in- door and outdoor sources. For the residential buildings adjacent to heavy traffic roads, outdoors traffic noise is the main source that affects indoor acoustic quality and health. Ventilation and outdoor noise prevention become a pair of contradictions for the residents in China nowadays for those buildings adjacent to heavy traffic roads. It is investigated that traffic noise emission is mainly con- stituted by the motors of trucks, buses and motorcycles as well as brake. In this paper, two methods of traffic noise reduction on the indoor sound environment and comfort are carried out to study and compare the residential buildings adjacent to heavy traffic roadway in a city. One is to install noise barriers on the two sides of the roadway, which consist of sound-proof glass and plas- tic materials. The effect of sound-insulation of this method is heavily dependent on the relative distance between the noise bar- rier and indoors. A reduction of sound with an average pressure level of 2–15dB is achieved on the places behind and under the noise barrier. However, for the equivalent of noise barrier height, the noise reduction effect is little. As for the places of higher than the noise barrier, the traffic noise will be even strengthened by 3–7dB. Noise increment can be seen at the points of distance farther than 15m and height more than noise barrier; the noise reduction effect is not satisfactory or even worsened. In addition, not every location is appropriate to install the noise barrier along the heavy traffic roads. The other method of noise reduction for the buildings adjacent to heavy traffic is to install the airproof and soundproof windows, which is the conversion from natural venti- lation to mechanical ventilation. A reduction of sound with an average pressure level of 5dB to 17dB can be achieved compared with common glass windows, if adopting sound proof glass win- dows. These two methods are helpful to isolate high frequency noise but not for low frequency noise. For those frequency noises, installing thick and cotton curtain and porous carpet can only decrease 2.4–4.5dB, which hardly contributes to indoor sound comfort, so further study is demanded to cut down traffic noise, especially to cut down the low frequency noise.
文摘An understanding of the influence of contractor monitoring on performance of road infrastructural projects in Uganda provided an impetus for this study. The objectives of the study were to: assess the relationship between contractors monitoring and performance of national road infrastructure projects and the relationship between contractor monitoring components and performance of national road infrastructure projects in Uganda. Purposive sampling was employed in selecting the procurement professionals, engineers and simple random sampling was adopted in selecting private consultants, members of parliament and respondents from the civil society organizations. Data for this study were collected using a closed ended questionnaire and interviews. Some of the major finding from this study include: weak procurement rules which lead to awarding road projects to incompetent contractors;contractor monitoring being handled by unqualified, incompetent and inexperienced professionals;lack of contractors and contract supervisors appraisal system;delay of contractors payments which affects timelines in services delivery;lack of a strong internal project monitoring and evaluation mechanism at the Uganda National Roads Agency (UNRA). The research therefore recommends the establishment of an Independent Public Infrastructure Development and Monitoring Unit by government and adoption of systems that appraise both contractors and contract supervisors with clear disciplinary actions for unsatisfactory performance by the UNRA.
基金This work was supported by the Green Shoots Plan,China[No.GS201826]the National Key Research and Development Program of China[2016YFC0208103]+1 种基金the National Natural Science Foundation of China[No.21607008]Special Project of Application basic Preface of Wuhan Science and Technology Bureau[No.2018060401011310].
文摘Vehicle emissions calculation methods mostly use ownership information or annual road monitoring data as the activity level to calculate air pollutant emissions,but it is hard to reflect either the emissions intensity under different conditions or the spatiotemporal characteristics in various sections based on such approaches.This paper presents a method based on the Macroscopic Fundamental Diagram and real-time traffic data to calculate vehicle emissions,which could reflect the operation conditions and emission characteristics of vehicles.Following the‘Technical Guide for the Compiling of Road Vehicle Air Pollutant Emissions Inventories’,the emissions of three roads with different lane numbers and road grades in Beijing were estimated and verified using this method.Compared with monitoring data,the average deviations of the traffic flow on the Fifth Expressway,Jingfu National Highway,and Jingzhou Provincial Highway were?25.5%,?26.5%,and?13.4%,respectively,and the average deviations of nitrogen oxides emissions were?27.7%,?12.9%,and?12%,respectively.This method showed good application potentials to construct the emissions inventory applied to the block-scale model and analyze the spatiotemporal distribution characteristics of motor vehicle emissions in urban areas.
基金Supported by the Science and Technology Development Planning Project of Binzhou City,Shandong Province(2014ZC0331)
文摘Wind speed,temperature,relative humidity and TSP concentration at three intersections in Binzhou City were monitored,and the relationships of TSP concentration with wind speed,temperature,relative humidity and traffic flow at the three intersections in Binzhou City were analyzed by using SPSS.The results show that traffic flow was the main factor affecting TSP concentration of road traffic in Binzhou City.