Sun Dihua

A traffic flow lattice model considering relative current influence and its numerical simulation

Based on Xues lattice model, an extended lattice model is proposed by considering the relative current information about next-nearest-neighbour sites ahead. The linear stability condition of the presented model is obtained by employing the linear stability theory. The density wave is investigated analytically with the perturbation method. The results show that the occurrence of traffic jamming transitions can be described by the kink–antikink solution of the modified Korteweg-de Vries (mKdV) equation. The simulation results are in good agreement with the analytical results, showing that the stability of traffic flow can be enhanced when the relative current of next-nearest-neighbour sites ahead is considered.

Multiple car-following model of traffic flow and numerical simulation

On the basis of the full velocity difference (FVD) model, an improved multiple car-following (MCF) model is proposed by taking into account multiple information inputs from preceding vehicles. The linear stability condition of the model is obtained by using the linear stability theory. Through nonlinear analysis, a modified Korteweg-de Vries equation is constructed and solved. The traffic jam can thus be described by the kink–antikink soliton solution for the mKdV equation. The improvement of this new model over the previous ones lies in the fact that it not only theoretically retains many strong points of the previous ones, but also performs more realistically than others in the dynamical evolution of congestion. Furthermore, numerical simulation of traffic dynamics shows that the proposed model can avoid the disadvantage of negative velocity that occurs at small sensitivity coefficients λ in the FVD model by adjusting the information on the multiple leading vehicles. No collision occurs and no unrealistic deceleration appears in the improved model.

Density waves in a lattice hydrodynamic traffic flow model with the anticipation effect

By introducing the traffic anticipation effect in the real world into the original lattice hydrodynamic model, we present a new anticipation effect lattice hydrodynamic (AELH) model, and obtain the linear stability condition of the model by applying the linear stability theory. Through nonlinear analysis, we derive the Burgers equation and Korteweg-de Vries (KdV) equation, to describe the propagating behaviour of traffic density waves in the stable and the metastable regions, respectively. The good agreement between simulation results and analytical results shows that the stability of traffic flow can be enhanced when the anticipation effect is considered.

Continuum modeling for two-lane traffic flow with consideration of the traffic interruption probability

Considering the effects that the probability of traffic interruption and the friction between two lanes have on the car-following behaviour, this paper establishes a new two-lane microscopic car-following model. Based on this microscopic model, a new macroscopic model was deduced by the relevance relation of microscopic and macroscopic scale parameters for the two-lane traffic flow. Terms related to lane change are added into the continuity equations and velocity dynamic equations to investigate the lane change rate. Numerical results verify that the proposed model can be efficiently used to reflect the effect of the probability of traffic interruption on the shock, rarefaction wave and lane change behaviour on two-lane freeways. The model has also been applied in reproducing some complex traffic phenomena caused by traffic accident interruption.

A viscous continuum traffic flow model with consideration of the coupling effect for two-lane freeways

In this paper, the viscous continuum traffic flow model for a single lane is extended to the traffic flow for two-lane freeways. The proposed model is a higher-order continuum model considering the coupling and lane changing effects of the vehicles on two adjacent lanes. It results from integrating the Taylor series expansion of the viscous continuum traffic flow model proposed by Ge (2006 Physica A 371 667) into the multi-lane model presented by Daganzo (1997 Transpn. Res. B 31 83). Our proposed model may be used to describe non-anisotropic behaviour because of lane changing in multi-lane traffic. A linear stability analysis is given and the neutral stability condition is obtained. Also, issues related to lane changing, shock waves and rarefaction waves, local clustering and phase transition are investigated through a simulation experiment. The simulation results show that the proposed model is capable of explaining some particular traffic phenomena commonly observable in real world traffic flow.

Feedback control scheme of traffic jams based on the coupled map car-following model

Based on the pioneering work of Konishi et al. [Phys. Rev. E (1999) 60 4000], a new feedback control scheme is presented to suppress traffic jams based on the coupled map car-following model under the open boundary condition. The effect of the safe headway on the traffic system is considered. According to the control theory, the condition under which traffic jams can be suppressed is analyzed. The results are compared with the previous results concerning congestion control. The simulations show that the suppression performance of our scheme on traffic jams is better than those of the previous schemes, although all the schemes can suppress traffic jams. The simulation results are consistent with theoretical analyses.

RFID-based production operation management for multi-varieties and small-batch production

The rapid changing market is making manufacturing systems increasingly trend to multi-varieties and small-batch production. It drives that strict production operation management in detail is done. In this paper RFID tags are introduced to overcome difficulty to identity important production elements in workshop. A tag data model of production element is proposed, and the architecture and integration operation mode of corresponding production operation management system are established. Then, an information fusion model of real-time heterogeneous production data from multi-sources and implementation methods of rapidly reconfigurable production operation management system based on component are presented. The application results in a motorcycle assembly line show the production efficiency and quality are obviously improved.

Vehicle formation analysis based on zero dynamics for road traffic system

Car-following models play an important role in the field of road traffic system, and one of its important issues is the vehicle formation. To conduct the analysis of vehicle formation, this paper introduces the concept of zero dynamics and gives a detailed analysis of the full velocity difference (FVD) model. Meanwhile, the stability analysis of FVD model based on the Lyapunov function is also discussed, and the result validates that the vehicle formation can achieve asymptotic stability.

Simulation of pedestrian behaviors based on an improved floor field cellular automaton model under attractive incidents

The study of pedestrian dynamics is very significant for promoting pedestrian traffic management and optimizing the layout of public facility in comprehensive transportation hubs, markets, theaters etc. In order to simulate and reproduce pedestrian behaviors under attractive incidents, an improved floor field model is proposed in this paper. This improved model is composed of static floor field, dynamic floor field and the new proposed attractive field, which takes into account the attractive degree of incident, view distance of onlooker, and pedestrians safe psychological distance. The transition probability of pedestrian is decided by the interaction of static floor field, dynamic floor field and attractive field. Besides, pedestrian movement state is divided into three types under attractive incidents: walking, staying, and leaving, which can depict the pedestrian behaviors of gathering, looking and dissipation. The experiment results show that our proposed model can reproduce the onlooking processes and capture the typical characteristics of torus-shaped phenomenon under attractive incidents.

Fuzzy evaluation of traffic flow stability based on the discreteness of traffic parameters

The microscopic traffic flow stability is difficult to describe the influences of the dynamic relationship between vehicles on traffic conditions. In order to solve the problem, from the perspective of macroscopic and microscopic parameters of traffic flow and considering the discreteness of velocity and following distance, the paper selected average velocity, average following distance, the variation coefficient of velocity and following distance as the traffic flow stability indices. And a stability evaluation model was constructed based on fuzzy theory. Using VISSIM simulation software, simulation experiment was carried out. The influences of traffic volume, traffic incident, traffic signals and GPS permeability on traffic flow stability evaluation were analyzed. Results show that traffic flow stability decreases gradually with the increase of volume. When there is a traffic incident, traffic flow stability decreases at the upstream section, while it is contrary to the downstream section. With the decrease of GPS permeability, the differences of the four indices and traffic flow stability at these GPS permeability with that of full permeability are becoming bigger and bigger. So the behavior described by the model is consistent with the actual state of the traffic system, proving that the model is real and effective. Thus it can be used to evaluate urban traffic flow stability macroscopically.