As a convenient passenger transit facility between floors with different heights, escalators have been extensively used in shopping malls, metro stations, airport terminals, etc. Compared with other vertical transit f...As a convenient passenger transit facility between floors with different heights, escalators have been extensively used in shopping malls, metro stations, airport terminals, etc. Compared with other vertical transit facilities including stairs and elevators, escalators usually have large transit capacity. It is expected to reduce pedestrian traveling time and thus improve the quality of pedestrian’s experiences especially in jamming conditions. However, it is noticed that pedestrians may present different movement patterns, e.g., queuing on each step of the escalator, walking on the left-side and meanwhile standing on the right-side of the escalator. These different patterns affect the actual escalator traffic volume and finally the passenger spatiotemporal distribution in different built environments. Thus, in the present study, a microscopic cellular automaton(CA) simulation model considering pedestrian movement behavior on escalators is built. Simulations are performed considering different pedestrian movement speeds, queuing modes, and segregation on escalators with different escalator speeds.The actual escalator capacities under different pedestrian movement patterns are investigated. It is found that walking on escalators will not always benefit escalator transit volume improvement, especially in jamming conditions.展开更多
A cellular automaton model for the ventricular myocardium considering the layer structure has been established. The three types of cells in this model differ principally in the repolarization characteristics. For the ...A cellular automaton model for the ventricular myocardium considering the layer structure has been established. The three types of cells in this model differ principally in the repolarization characteristics. For the normal travelling waves in this model, the computer simulation results show the R, S, and T waves and they are qualitatively in agreement with the standard electrocardiograph. Phenomena such as the potential decline of point J and segment ST and the rise of the potential line after the T wave appear when the ischemia occurs in the endocardium. The spiral wave has also been simulated, and the corresponding potential has a lower amplitude, higher frequency, and wider R wave, which accords with the distinguishing feature of the clinical electrocardiograph. Mechanisms underlying the above phenomena are analyzed briefly.展开更多
As an important traffic mode, urban rail transit is constantly developing toward improvement in service capacity and quality. When an urban rail transit system is evaluated in terms of its service capacity, the train ...As an important traffic mode, urban rail transit is constantly developing toward improvement in service capacity and quality. When an urban rail transit system is evaluated in terms of its service capacity, the train departure capacity is an important index that can objectively reflect the service level of an urban rail transit facility. In light of the existing cellular automaton models, this paper proposes a suitable cellular automaton model to analyze the train departure capacity of urban rail transit under different variable factors and conditions. The established model can demonstrate the train operating processes by implementing the proposed sound rules, including the rules of train departure at the origin and intermediate stations, and the velocity and position updating rules. The properties of train traffic are analyzed via numerical experiments. The numerical results show that the departure capacity is negatively affected by the train departure control manner. In addition, （i） the real-time signal control can offer a higher train service frequency; （ii） the departure capacity gradually rises with the decrease in the line design speed to a limited extent; （iii） the departure capacity decreases with extension in the train length; （iv） the number of departed trains decreases as the train stop time increases; （v） the departure capacity is not affected by the section length. However, the longer the length, the worse the service quality of the urban rail transit line. The experiments show that the proposed cellular automaton model can be used to analyze the train service capacity of an urban rail transit system by performing quantitative analysis under various considered factors, conditions, and management modes.展开更多
A numerical model is developed by coupling the cellular automaton(CA)method and the lattice Boltzmann method(LBM)to simulate the dendritic growth of Al-Cu alloy in both two and three dimensions.An improved decentered ...A numerical model is developed by coupling the cellular automaton(CA)method and the lattice Boltzmann method(LBM)to simulate the dendritic growth of Al-Cu alloy in both two and three dimensions.An improved decentered square algorithm is proposed to overcome the artificial anisotropy induced by the CA cells and to realize simulation of dendritic growth with arbitrary orientations.Based on the established CA-LBM model,effects of forced convection and gravity-driven natural convection on dendritic growth are studied.The simulation results show that the blocking effect of dendrites on melt flow is advanced with a larger number of seeds.The competitive growth of the converging columnar dendrites is determined by the interaction between heat flow and forced convection.Gravity-driven natural convection leads to highly asymmetric growth of equiaxed dendrites.With sinking downwards of the heavy solute,chimney-like or mushroom-like solute plumes are formed in the melt in front of the columnar dendrites when they grow along the gravitational direction.More details on dendritic growth of Al-Cu alloy under convection are revealed by 3D simulations.展开更多
This paper proposes an improved cellular automaton model to describe the urban traffic flow with the consideration of traffic light and driving behaviour effects. Based on the model, the characteristics of the urban t...This paper proposes an improved cellular automaton model to describe the urban traffic flow with the consideration of traffic light and driving behaviour effects. Based on the model, the characteristics of the urban traffic flow on a single- lane road are investigated under three different control strategies, i.e., the synchronized, the green wave and the random strategies. The fundamental diagrams and time-space patterns of the traffic flows are provided for these strategies respectively. It finds that the dynamical transition to the congested flow appears when the vehicle density is higher than a critical level. The saturated flow is less dependent on the cycle time and the strategies of the traffic light control, while the critical vehicle density varies with the cycle time and the strategies. Simulated results indicate that the green wave strategy is proven to be the most effective one among the above three control strategies.展开更多
A new reliable cellular automaon(CA) model designed to account for stochasticity in traffic flow induced by heterogeneity in driving behavior is presented.The proposed model differs from most existing CA models in tha...A new reliable cellular automaon(CA) model designed to account for stochasticity in traffic flow induced by heterogeneity in driving behavior is presented.The proposed model differs from most existing CA models in that this new model focuses on describing traffic phenomena by coding into its rules the key idea that a vehicle's moving state is directly determined by a driver stepping on the accelerator or on the brake(the vehicle's acceleration).Acceleration obeys a deformed continuous distribution function when considering the heterogeneity in driving behavior and the safe distance, rather than equaling a fixed acceleration value with a probability, as is the rule in many existing CA models.Simulation results show that the new proposed model is capable of reproducing empirical findings in real traffic system.Moreover, this new model makes it possible to implement in-depth analysis of correlations between a vehicle's state parameters.展开更多
In this paper, we incorporate new parameters into a cellular automaton traffic flow model proposed in our previous paper [Jin et al. 2010 J. Stat. Mech. 2010 P03018]. Through these parameters, we adjust the anticipate...In this paper, we incorporate new parameters into a cellular automaton traffic flow model proposed in our previous paper [Jin et al. 2010 J. Stat. Mech. 2010 P03018]. Through these parameters, we adjust the anticipated velocity and the acceleration threshold separately. It turns out that the flow rate of synchronized flow mainly changes with the anticipated velocity, and the F →S phase transition feature mainly changes with the acceleration threshold. Therefore, we conclude that the acceleration threshold is the major factor affecting the F → S phase transition.展开更多
The study of the panic evacuation process is of great significance to emergency management.Panic not only causes negative emotions such as irritability and anxiety,but also affects the pedestrians decision-making proc...The study of the panic evacuation process is of great significance to emergency management.Panic not only causes negative emotions such as irritability and anxiety,but also affects the pedestrians decision-making process,thereby inducing the abnormal crowd behavior.Prompted by the epidemiological SIR model,an extended floor field cellular automaton model was proposed to investigate the pedestrian dynamics under the threat of hazard resulting from the panic contagion.In the model,the conception of panic transmission status(PTS)was put forward to describe pedestrians’behavior who could transmit panic emotions to others.The model also indicated the pedestrian movement was governed by the static and hazard threat floor field.Then rules that panic could influence decision-making process were set up based on the floor field theory.The simulation results show that the stronger the pedestrian panic,the more sensitive pedestrians are to hazards,and the less able to rationally find safe exits.However,when the crowd density is high,the panic contagion has a less impact on the evacuation process of pedestrians.It is also found that when the hazard position is closer to the exit,the panic will propagate for a longer time and have a greater impact on the evacuation.The results also suggest that as the extent of pedestrian’s familiarity with the environment increases,pedestrians spend less time to escape from the room and are less sensitive to the hazard.In addition,it is essential to point out that,compared with the impact of panic contagion,the pedestrian’s familiarity with environment has a more significant influence on the evacuation.展开更多
It is known that the commonly used NaSch cellular automaton （CA） model and its modifications can help explain the internal causes of the macro phenomena of traffic flow. However, the randomization probability of veh...It is known that the commonly used NaSch cellular automaton （CA） model and its modifications can help explain the internal causes of the macro phenomena of traffic flow. However, the randomization probability of vehicle velocity used in these models is assumed to be an exogenous constant or a conditional constant, which cannot reflect the learning and forgetting behaviour of drivers with historical experiences. This paper further modifies the NaSch model by enabling the randomization probability to be adjusted on the bases of drivers＇ memory. The Markov properties of this modified model are discussed. Analytical and simulation results show that the traffic fundamental diagrams can be indeed improved when considering drivers＇ intelligent behaviour. Some new features of traffic are revealed by differently combining the model parameters representing learning and forgetting behaviour.展开更多
This paper modifies the weighted probabilistic cellular automaton model （Li X L, Kuang H, Song T, et al 2008 Chin. Phys. B 17 2366） which considered a diversity of traffic behaviors under real traffic situations ind...This paper modifies the weighted probabilistic cellular automaton model （Li X L, Kuang H, Song T, et al 2008 Chin. Phys. B 17 2366） which considered a diversity of traffic behaviors under real traffic situations induced by various driving characters and habits. In the new model, the effects of the velocity at the last time step and drivers＇ desire for acceleration are taken into account. The fundamental diagram, spatial-temporal diagram, and the time series of one-minute data are analyzed. The results show that this model reproduces synchronized flow. Finally, it simulates the on-ramp system with the proposed model. Some characteristics including the phase diagram are studied.展开更多
According to the railway transportation system＇s characteristics, a new cellular automaton model for the single- line railway system is presented in this paper. Based on this model, several simulations were done to i...According to the railway transportation system＇s characteristics, a new cellular automaton model for the single- line railway system is presented in this paper. Based on this model, several simulations were done to imitate the train operation under three working diagrams. From a different angle the results show how the organization of train operation impacts on the railway carrying capacity. By using the non-parallel train working diagram the influence of fast-train on slow-train is found to be the strongest. Many slow-trains have to wait in-between neighbouring stations to let the fast-train（s） pass through first. So the slow-train will advance like a wave propagating from the departure station to the arrival station. This also resembles the situation of a highway jammed traffic flow. Furthermore, the nonuniformity of travel times between the sections also greatly limits the railway carrying capacity. After converting the nonuniform sections into the sections with uniform travel times while the total travel time is kept unchanged, all three carrying capacities are improved greatly as shown by simulation. It also shows that the cellular automaton model is an effective and feasible way to investigate the railway transportation system.展开更多
Recently, a number of efforts are underway to investigate inter-vehicle communications （IVC）. This paper studies the instantaneous information propagation behaviours based on IVC in three different tragic situations...Recently, a number of efforts are underway to investigate inter-vehicle communications （IVC）. This paper studies the instantaneous information propagation behaviours based on IVC in three different tragic situations （free flow, synchronized flow and stop-and-go waves） in a cellular automaton model. It is shown that different behaviours appear in stop-and-go waves from those in free flow and synchronized flow. While the distribution of Multi-hop Communication Distance （MhCD） is either exponential or uniform in free flow and synchronized flow, the distribution of MhCD is either exponential or with a single peak in stop-and-go waves.展开更多
A wafer-scale colloidal monolayer consisting of SiO2 spheres is fabricated by a method combining spin coating and thermal treatment for the first time. Moreover, a new cellular automaton model describing the self-asse...A wafer-scale colloidal monolayer consisting of SiO2 spheres is fabricated by a method combining spin coating and thermal treatment for the first time. Moreover, a new cellular automaton model describing the self-assembly process of the colloidal monolayer is introduced. Rather than simulate molecular self-assembly to establish the most energetically favored position, we reconstruct the self-assembly of the colloidal monolayer by adjusting several simple transition rules of a cellular automaton. This model captures the main self-assembly characteristics of SiO2 spheres, including experimental processing time, morphology, and some statistics. It possesses the advantage of less calculation and higher efficiency, paving a new way to simulate a mesoscopic system.展开更多
This paper uses the cellular automaton model to study the dynamics of traffic flow around an on-ramp with an acceleration lane. It adopts a parameter, which can reflect different lane-changing behaviour, to represent ...This paper uses the cellular automaton model to study the dynamics of traffic flow around an on-ramp with an acceleration lane. It adopts a parameter, which can reflect different lane-changing behaviour, to represent the diversity of driving behaviour. The refined cellular automaton model is used to describe the lower acceleration rate of a vehicle. The phase diagram and the capacity of the on-ramp system are investigated. The simulation results show that in the single cell model, the capacity of the on-ramp system will stay at the highest flow of a one lane system when the driver is moderate and careful; it will be reduced when the driver is aggressive. In the refined cellular automaton model, the capacity is always reduced even when the driver is careful. It proposes that the capacity drop of the on-ramp system is caused by aggressive lane-changing behaviour and lower acceleration rate.展开更多
In this paper, we further analyze our cellular automaton （CA） traffic flow model. By changing some parameters, the characteristics of our model can be significantly varied, ranging from the features of phase transit...In this paper, we further analyze our cellular automaton （CA） traffic flow model. By changing some parameters, the characteristics of our model can be significantly varied, ranging from the features of phase transitions to the number of traffic phases. We also review the other CA models based on Kerner＇s three-phase traffic theory. By comparisons, we find that the core concepts for modeling the synchronized flow in these models are similar. Our model can be a good candidate for modeling the synchronized flow, since there is enough flexibility in our framework.展开更多
Cellular Automaton （CA） based traffic flow models have been extensively studied due to their effectiveness and simplicity in recent years. This paper develops a discrete time Markov chain （DTMC） analytical framewo...Cellular Automaton （CA） based traffic flow models have been extensively studied due to their effectiveness and simplicity in recent years. This paper develops a discrete time Markov chain （DTMC） analytical framework for a Nagel-Schreckenberg and Fukui Ishibashi combined CA model （W^2H traffic flow model） from microscopic point of view to capture the macroscopic steady state speed distributions. The inter-vehicle spacing Maxkov chain and the steady state speed Markov chain are proved to be irreducible and ergodic. The theoretical speed probability distributions depending on the traffic density and stochastic delay probability are in good accordance with numerical simulations. The derived fundamental diagram of the average speed from theoretical speed distributions is equivalent to the results in the previous work.展开更多
The combined bottleneck effect is investigated by modeling traffic systems with an on-ramp and a nearby bus stop in a two-lane cellular automaton model. Two cases, i.e. the bus stop locates in the downstream section o...The combined bottleneck effect is investigated by modeling traffic systems with an on-ramp and a nearby bus stop in a two-lane cellular automaton model. Two cases, i.e. the bus stop locates in the downstream section of the on-ramp and the bus stop locates in the upstream section of the on-ramp, are considered separately. The upstream flux and downstream flux of the main road, as well as the on-ramp flux are analysed in detail, with respect to the entering probabilities and the distance between the on-ramp and the bus stop. It is found that the combination of the two bottlenecks causes the capacity to drop off, because the vehicles entering the main road from the on-ramp would interweave with the stopping （pulling-out） buses in the downstream （upstream） case. The traffic conflict in the former case is much heavier than that in the latter, causing the downstream main road to be utilized inefficiently. This suggests that the bus stop should be set in the upstream section of the on-ramp to enhance the capacity. The fluxes both on the main road and on the on-ramp vary with the distance between the two bottlenecks in both cases. However, the effects of distance disappear gradually at large distances. These findings might give some guidance to traffic optimization and management.展开更多
A minimal cellular automaton model is introduced to describe the collective motion of self-propelled particles on two-dimensional square lattice. The model features discretization of directional and positional spaces ...A minimal cellular automaton model is introduced to describe the collective motion of self-propelled particles on two-dimensional square lattice. The model features discretization of directional and positional spaces and single-particle occupation on one lattice site. Contrary to the Vicsek model and its variants, our model exhibits the nonvanishing optimal noise. When the particle density increases, the collective motion is promoted with optimal noise strength and reduced with noise strength out of optimal region. In addition, when the square lattice undergoes edge percolation process, no abrupt change of alignment behaviors is observed at the critical point of percolation.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.71473207 and 71871189)the Research Grant Council of the Hong Kong Administrative Region,China(Grant No.CityU118909)the Open Fund of Beijing Engineering and Technology Research Center of Rail Transit Line Safety and Disaster Prevention(Grant No.RRC201701)
文摘As a convenient passenger transit facility between floors with different heights, escalators have been extensively used in shopping malls, metro stations, airport terminals, etc. Compared with other vertical transit facilities including stairs and elevators, escalators usually have large transit capacity. It is expected to reduce pedestrian traveling time and thus improve the quality of pedestrian’s experiences especially in jamming conditions. However, it is noticed that pedestrians may present different movement patterns, e.g., queuing on each step of the escalator, walking on the left-side and meanwhile standing on the right-side of the escalator. These different patterns affect the actual escalator traffic volume and finally the passenger spatiotemporal distribution in different built environments. Thus, in the present study, a microscopic cellular automaton(CA) simulation model considering pedestrian movement behavior on escalators is built. Simulations are performed considering different pedestrian movement speeds, queuing modes, and segregation on escalators with different escalator speeds.The actual escalator capacities under different pedestrian movement patterns are investigated. It is found that walking on escalators will not always benefit escalator transit volume improvement, especially in jamming conditions.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11365003 and 11165004)
文摘A cellular automaton model for the ventricular myocardium considering the layer structure has been established. The three types of cells in this model differ principally in the repolarization characteristics. For the normal travelling waves in this model, the computer simulation results show the R, S, and T waves and they are qualitatively in agreement with the standard electrocardiograph. Phenomena such as the potential decline of point J and segment ST and the rise of the potential line after the T wave appear when the ischemia occurs in the endocardium. The spiral wave has also been simulated, and the corresponding potential has a lower amplitude, higher frequency, and wider R wave, which accords with the distinguishing feature of the clinical electrocardiograph. Mechanisms underlying the above phenomena are analyzed briefly.
基金Project supported by the National Natural Science Foundation of China(Grant No.U1434207)
文摘As an important traffic mode, urban rail transit is constantly developing toward improvement in service capacity and quality. When an urban rail transit system is evaluated in terms of its service capacity, the train departure capacity is an important index that can objectively reflect the service level of an urban rail transit facility. In light of the existing cellular automaton models, this paper proposes a suitable cellular automaton model to analyze the train departure capacity of urban rail transit under different variable factors and conditions. The established model can demonstrate the train operating processes by implementing the proposed sound rules, including the rules of train departure at the origin and intermediate stations, and the velocity and position updating rules. The properties of train traffic are analyzed via numerical experiments. The numerical results show that the departure capacity is negatively affected by the train departure control manner. In addition, （i） the real-time signal control can offer a higher train service frequency; （ii） the departure capacity gradually rises with the decrease in the line design speed to a limited extent; （iii） the departure capacity decreases with extension in the train length; （iv） the number of departed trains decreases as the train stop time increases; （v） the departure capacity is not affected by the section length. However, the longer the length, the worse the service quality of the urban rail transit line. The experiments show that the proposed cellular automaton model can be used to analyze the train service capacity of an urban rail transit system by performing quantitative analysis under various considered factors, conditions, and management modes.
基金Project supported by the National Natural Science Foundation of China(Grant No.51805389)the Key R&D Program of Hubei Province,China(Grant No.2021BAA048)+1 种基金the 111 Project(Grant No.B17034)the fund of Hubei Key Laboratory of Advanced Technology for Automotive Components,Wuhan University of Technology(Grant No.XDQCKF2021011).
文摘A numerical model is developed by coupling the cellular automaton(CA)method and the lattice Boltzmann method(LBM)to simulate the dendritic growth of Al-Cu alloy in both two and three dimensions.An improved decentered square algorithm is proposed to overcome the artificial anisotropy induced by the CA cells and to realize simulation of dendritic growth with arbitrary orientations.Based on the established CA-LBM model,effects of forced convection and gravity-driven natural convection on dendritic growth are studied.The simulation results show that the blocking effect of dendrites on melt flow is advanced with a larger number of seeds.The competitive growth of the converging columnar dendrites is determined by the interaction between heat flow and forced convection.Gravity-driven natural convection leads to highly asymmetric growth of equiaxed dendrites.With sinking downwards of the heavy solute,chimney-like or mushroom-like solute plumes are formed in the melt in front of the columnar dendrites when they grow along the gravitational direction.More details on dendritic growth of Al-Cu alloy under convection are revealed by 3D simulations.
基金supported by the Strategic Research Grants from City University of Hong Kong [Project No. CityU-SRG 7002370]the National Natural Science Foundation of China (Grant No. 10972135)+1 种基金Science Foundation of Shanghai Maritime University(Grant No. 20110046)the Science Foundation of Shanghai Science Commission (Grant Nos. 09DZ2250400 and 09530708200)
文摘This paper proposes an improved cellular automaton model to describe the urban traffic flow with the consideration of traffic light and driving behaviour effects. Based on the model, the characteristics of the urban traffic flow on a single- lane road are investigated under three different control strategies, i.e., the synchronized, the green wave and the random strategies. The fundamental diagrams and time-space patterns of the traffic flows are provided for these strategies respectively. It finds that the dynamical transition to the congested flow appears when the vehicle density is higher than a critical level. The saturated flow is less dependent on the cycle time and the strategies of the traffic light control, while the critical vehicle density varies with the cycle time and the strategies. Simulated results indicate that the green wave strategy is proven to be the most effective one among the above three control strategies.
基金Project supported by the National Key Research and Development Program of China(Grant No.2018YFC0809900)the National Natural Science Foundation of China(Grant Nos.71774093 and 71473146)
文摘A new reliable cellular automaon(CA) model designed to account for stochasticity in traffic flow induced by heterogeneity in driving behavior is presented.The proposed model differs from most existing CA models in that this new model focuses on describing traffic phenomena by coding into its rules the key idea that a vehicle's moving state is directly determined by a driver stepping on the accelerator or on the brake(the vehicle's acceleration).Acceleration obeys a deformed continuous distribution function when considering the heterogeneity in driving behavior and the safe distance, rather than equaling a fixed acceleration value with a probability, as is the rule in many existing CA models.Simulation results show that the new proposed model is capable of reproducing empirical findings in real traffic system.Moreover, this new model makes it possible to implement in-depth analysis of correlations between a vehicle's state parameters.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10872194 and 50738001)
文摘In this paper, we incorporate new parameters into a cellular automaton traffic flow model proposed in our previous paper [Jin et al. 2010 J. Stat. Mech. 2010 P03018]. Through these parameters, we adjust the anticipated velocity and the acceleration threshold separately. It turns out that the flow rate of synchronized flow mainly changes with the anticipated velocity, and the F →S phase transition feature mainly changes with the acceleration threshold. Therefore, we conclude that the acceleration threshold is the major factor affecting the F → S phase transition.
基金supported by the National Key Technology Research and Development Program of China(Grant No.2019YFC0810804)the National Natural Science Foundation of China(Grant No.7197010332)。
文摘The study of the panic evacuation process is of great significance to emergency management.Panic not only causes negative emotions such as irritability and anxiety,but also affects the pedestrians decision-making process,thereby inducing the abnormal crowd behavior.Prompted by the epidemiological SIR model,an extended floor field cellular automaton model was proposed to investigate the pedestrian dynamics under the threat of hazard resulting from the panic contagion.In the model,the conception of panic transmission status(PTS)was put forward to describe pedestrians’behavior who could transmit panic emotions to others.The model also indicated the pedestrian movement was governed by the static and hazard threat floor field.Then rules that panic could influence decision-making process were set up based on the floor field theory.The simulation results show that the stronger the pedestrian panic,the more sensitive pedestrians are to hazards,and the less able to rationally find safe exits.However,when the crowd density is high,the panic contagion has a less impact on the evacuation process of pedestrians.It is also found that when the hazard position is closer to the exit,the panic will propagate for a longer time and have a greater impact on the evacuation.The results also suggest that as the extent of pedestrian’s familiarity with the environment increases,pedestrians spend less time to escape from the room and are less sensitive to the hazard.In addition,it is essential to point out that,compared with the impact of panic contagion,the pedestrian’s familiarity with environment has a more significant influence on the evacuation.
基金supported by the National Natural Science Foundation of China (Grant No. 70821061)the National Basic Research Program of China (Grant No. 2006CB705503)
文摘It is known that the commonly used NaSch cellular automaton （CA） model and its modifications can help explain the internal causes of the macro phenomena of traffic flow. However, the randomization probability of vehicle velocity used in these models is assumed to be an exogenous constant or a conditional constant, which cannot reflect the learning and forgetting behaviour of drivers with historical experiences. This paper further modifies the NaSch model by enabling the randomization probability to be adjusted on the bases of drivers＇ memory. The Markov properties of this modified model are discussed. Analytical and simulation results show that the traffic fundamental diagrams can be indeed improved when considering drivers＇ intelligent behaviour. Some new features of traffic are revealed by differently combining the model parameters representing learning and forgetting behaviour.
基金supported by the State Key Development Program for Basic Research of China (Grant No 2006CB705500)the National Natural Science Foundation of China (Grant Nos 70631001,70501004 and 70701004)Program for New Century Excellent Talents in University (Grant No CET-07-0057)
文摘This paper modifies the weighted probabilistic cellular automaton model （Li X L, Kuang H, Song T, et al 2008 Chin. Phys. B 17 2366） which considered a diversity of traffic behaviors under real traffic situations induced by various driving characters and habits. In the new model, the effects of the velocity at the last time step and drivers＇ desire for acceleration are taken into account. The fundamental diagram, spatial-temporal diagram, and the time series of one-minute data are analyzed. The results show that this model reproduces synchronized flow. Finally, it simulates the on-ramp system with the proposed model. Some characteristics including the phase diagram are studied.
文摘According to the railway transportation system＇s characteristics, a new cellular automaton model for the single- line railway system is presented in this paper. Based on this model, several simulations were done to imitate the train operation under three working diagrams. From a different angle the results show how the organization of train operation impacts on the railway carrying capacity. By using the non-parallel train working diagram the influence of fast-train on slow-train is found to be the strongest. Many slow-trains have to wait in-between neighbouring stations to let the fast-train（s） pass through first. So the slow-train will advance like a wave propagating from the departure station to the arrival station. This also resembles the situation of a highway jammed traffic flow. Furthermore, the nonuniformity of travel times between the sections also greatly limits the railway carrying capacity. After converting the nonuniform sections into the sections with uniform travel times while the total travel time is kept unchanged, all three carrying capacities are improved greatly as shown by simulation. It also shows that the cellular automaton model is an effective and feasible way to investigate the railway transportation system.
基金Project supported by the National Basic Research Program of China(Grant No2006CB705500)the National Natural Science Foundation of China(Grant Nos10532060,10404025,70601026 and 10672160)+1 种基金the CAS special FoundationFoundation for the Author of National Excellent Doctoral Dissertation of China
文摘Recently, a number of efforts are underway to investigate inter-vehicle communications （IVC）. This paper studies the instantaneous information propagation behaviours based on IVC in three different tragic situations （free flow, synchronized flow and stop-and-go waves） in a cellular automaton model. It is shown that different behaviours appear in stop-and-go waves from those in free flow and synchronized flow. While the distribution of Multi-hop Communication Distance （MhCD） is either exponential or uniform in free flow and synchronized flow, the distribution of MhCD is either exponential or with a single peak in stop-and-go waves.
基金Project supported by the National Natural Science Foundation of China(Grant No.81172082)Anhui Provincial Scientific and Technological Project of China(Grant No.12010202035)
文摘A wafer-scale colloidal monolayer consisting of SiO2 spheres is fabricated by a method combining spin coating and thermal treatment for the first time. Moreover, a new cellular automaton model describing the self-assembly process of the colloidal monolayer is introduced. Rather than simulate molecular self-assembly to establish the most energetically favored position, we reconstruct the self-assembly of the colloidal monolayer by adjusting several simple transition rules of a cellular automaton. This model captures the main self-assembly characteristics of SiO2 spheres, including experimental processing time, morphology, and some statistics. It possesses the advantage of less calculation and higher efficiency, paving a new way to simulate a mesoscopic system.
基金Project supported by the State Key Development Program for Basic Research of China (Grant No.2006CB705500)the National Natural Science Foundation of China (Grant Nos.70631001,70501004 and 70701004)+1 种基金Program for New Century Excellent Talents in University (Grant No.NCET-07-0057)the Innovation Foundation of Science and Technology for Excellent Doctorial Candidate of Beijing Jiaotong University (Grant No.48025)
文摘This paper uses the cellular automaton model to study the dynamics of traffic flow around an on-ramp with an acceleration lane. It adopts a parameter, which can reflect different lane-changing behaviour, to represent the diversity of driving behaviour. The refined cellular automaton model is used to describe the lower acceleration rate of a vehicle. The phase diagram and the capacity of the on-ramp system are investigated. The simulation results show that in the single cell model, the capacity of the on-ramp system will stay at the highest flow of a one lane system when the driver is moderate and careful; it will be reduced when the driver is aggressive. In the refined cellular automaton model, the capacity is always reduced even when the driver is careful. It proposes that the capacity drop of the on-ramp system is caused by aggressive lane-changing behaviour and lower acceleration rate.
基金Project supported by the National Basic Research Program of China (Grant No.2012CB725400)the Scientific Research Foundation of Graduate School of Southeast University,China
文摘In this paper, we further analyze our cellular automaton （CA） traffic flow model. By changing some parameters, the characteristics of our model can be significantly varied, ranging from the features of phase transitions to the number of traffic phases. We also review the other CA models based on Kerner＇s three-phase traffic theory. By comparisons, we find that the core concepts for modeling the synchronized flow in these models are similar. Our model can be a good candidate for modeling the synchronized flow, since there is enough flexibility in our framework.
基金supported by the National Basic Research Program of China (Grant No 2007CB310800)the National Natural Science Foundation of China (Grant Nos 60772150 and 60703018)the National High Technology Research and Development Program of China (Grant No 2008AA01Z208)
文摘Cellular Automaton （CA） based traffic flow models have been extensively studied due to their effectiveness and simplicity in recent years. This paper develops a discrete time Markov chain （DTMC） analytical framework for a Nagel-Schreckenberg and Fukui Ishibashi combined CA model （W^2H traffic flow model） from microscopic point of view to capture the macroscopic steady state speed distributions. The inter-vehicle spacing Maxkov chain and the steady state speed Markov chain are proved to be irreducible and ergodic. The theoretical speed probability distributions depending on the traffic density and stochastic delay probability are in good accordance with numerical simulations. The derived fundamental diagram of the average speed from theoretical speed distributions is equivalent to the results in the previous work.
基金Project supported by the National Basic Research Program of China (Grant No 2006CB705500)the National Natural Science Foundation of China (Grant Nos 70631001,70701004 and 70501004)
文摘The combined bottleneck effect is investigated by modeling traffic systems with an on-ramp and a nearby bus stop in a two-lane cellular automaton model. Two cases, i.e. the bus stop locates in the downstream section of the on-ramp and the bus stop locates in the upstream section of the on-ramp, are considered separately. The upstream flux and downstream flux of the main road, as well as the on-ramp flux are analysed in detail, with respect to the entering probabilities and the distance between the on-ramp and the bus stop. It is found that the combination of the two bottlenecks causes the capacity to drop off, because the vehicles entering the main road from the on-ramp would interweave with the stopping （pulling-out） buses in the downstream （upstream） case. The traffic conflict in the former case is much heavier than that in the latter, causing the downstream main road to be utilized inefficiently. This suggests that the bus stop should be set in the upstream section of the on-ramp to enhance the capacity. The fluxes both on the main road and on the on-ramp vary with the distance between the two bottlenecks in both cases. However, the effects of distance disappear gradually at large distances. These findings might give some guidance to traffic optimization and management.
基金Project supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB33000000)the National Natural Science Foundation of China(Grant No.12090054)。
文摘A minimal cellular automaton model is introduced to describe the collective motion of self-propelled particles on two-dimensional square lattice. The model features discretization of directional and positional spaces and single-particle occupation on one lattice site. Contrary to the Vicsek model and its variants, our model exhibits the nonvanishing optimal noise. When the particle density increases, the collective motion is promoted with optimal noise strength and reduced with noise strength out of optimal region. In addition, when the square lattice undergoes edge percolation process, no abrupt change of alignment behaviors is observed at the critical point of percolation.
