Biomedical subjects

S Q Dai

Publications and source records attributed to S Q Dai.

4 recordsLinked to original sources

PubMed2005

Centrifugal force model for pedestrian dynamics.

In this paper, a centrifugal force model is developed for pedestrian dynamics. The effects of both the headway and the relative velocity among pedestrians are taken into account, which can be expressed by a "centrifugal force" term in dynamic equation. The jamming probability due to the arching at exits for crowd flows is provided. A quantitative analysis of the crowd flowing out of a hall shows that the average leaving time T is a function of the exit width W in negative power. The related simulation indicates that the proposed model is able to reproduce the self-organization phenomena of lane formation for sparse flows.

Behavior↗

PubMed2005

Stabilization analysis and modified Korteweg-de Vries equation in a cooperative driving system.

Two lattice traffic models are proposed by incorporating a cooperative driving system. The lattice versions of the hydrodynamic model of traffic flow are described by the differential-difference equation and difference-difference equation, respectively. The stability conditions for the two models are obtained using the linear stability theory. The results show that considering more than one site ahead in vehicle motion leads to the stabilization of the system. The modified Korteweg-de Vries equation (the mKdV equation, for short) near the critical point is derived by using the reductive perturbation method to show the traffic jam which is proved to be described by kink-anti-kink soliton solutions obtained from the mKdV equations.

Journal Article↗

PubMed2004

Stabilization effect of traffic flow in an extended car-following model based on an intelligent transportation system application.

An extended car following model is proposed by incorporating an intelligent transportation system in traffic. The stability condition of this model is obtained by using the linear stability theory. The results show that anticipating the behavior of more vehicles ahead leads to the stabilization of traffic systems. The modified Korteweg-de Vries equation (the mKdV equation, for short) near the critical point is derived by applying the reductive perturbation method. The traffic jam could be thus described by the kink-antikink soliton solution for the mKdV equation. From the simulation of space-time evolution of the vehicle headway, it is shown that the traffic jam is suppressed efficiently with taking into account the information about the motion of more vehicles in front, and the analytical result is consonant with the simulation one.

Journal Article↗

PubMed1993

The adsorption behaviour of dimethyltin from seawater onto sedimentary phase in Tianjin Harbor.

The adsorption of dimethyltin from a seawater matrix onto suspended particulate matter was studied. The influences of pH and salinity, adsorption isotherms at various temperatures, and the adsorption rate under certain experimental conditions were determined. It was found that the adsorption capacity was highest at c. pH 6 and decreased with increasing salinity. The adsorption behaviour at various temperatures was described best by a Langmuir isotherm. The adsorption capacity of dimethyltin was higher in natural seawater than in artificial seawater at the same temperature.

Journal Article↗