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Qing-Song Wu

Publications and source records attributed to Qing-Song Wu.

7 recordsLinked to original sources
PubMed2005

Toward an improvement over Kerner-Klenov-Wolf three-phase cellular automaton model.

The Kerner-Klenov-Wolf (KKW) three-phase cellular automaton model has a nonrealistic velocity of the upstream front in widening synchronized flow pattern which separates synchronized flow downstream and free flow upstream. This paper presents an improved model, which is a combination of the initial KKW model and a modified Nagel-Schreckenberg (MNS) model. In the improved KKW model, a parameter is introduced to determine the vehicle moves according to the MNS model or the initial KKW model. The improved KKW model can not only simulate the empirical observations as the initial KKW model, but also overcome the nonrealistic velocity problem. The mechanism of the improvement is discussed.

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PubMed2005

Formation of uniform CuO nanorods by spontaneous aggregation: Selective synthesis of CuO, Cu2O, and Cu nanoparticles by a solid-liquid phase arc discharge process.

Uniform and monodisperse CuO nanorods have been synthesized by directional aggregation and crystallization of tiny CuO nanoparticles generated from a solid-liquid arc discharge process under ambient conditions in the absence of any surfactants. Uniform CuO nanorods with sharp ends are formed from tiny nanoparticles via a process that involves the rapid oxidation of Cu nanoclusters, the spontaneous aggregation of CuO nanoparticles, and the Ostawald ripening process. The spontaneous aggregation and oriented attachment of tiny CuO nanoparticles contributed obviously to the formation of these kinds of nanostructures. By choice of suitable reducing agent to prevent the oxidation of Cu nanoclusters, Cu and Cu2O nanoparticles can be selectively synthesized.

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PubMed2004

Traffic behavior near an off ramp in the cellular automaton traffic model.

In this paper, we investigate the off-ramp system on the highway using the cellular automaton traffic model. Both the system without an exit lane (case 1) and that with an exit lane (case 2) are considered. The phase diagram and its variation with L(D) (the length of exit lane in case 2 and the length of a special lane-changing section in case 1) is studied. Two phase regions are found in case 1 and a new phase, i.e., the maximum flux phase, is reported in case 2. The density (velocity) distribution near the off ramp and the influence of L(D) on the traffic flow are also discussed in both cases.

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PubMed2003

Open boundaries in a cellular automata model for synchronized flow: effects of nonmonotonicity.

In this paper, we have discussed the traffic situations arising from the open boundary conditions (OBC) of a cellular automata model that can reproduce the synchronized flow. The model is different from the slow-to-start (STS) model in that the upper branch of the fundamental diagram in the periodic boundary conditions (PBC) is not monotonous but has an extremum. The phase diagram and the fundamental diagram of the model in the OBC are investigated. The results are compared with those of the STS model and those in the PBC. The current in the OBC as well as the density profiles in the different phases is also investigated.

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PubMed2003

Cellular automata model simulating complex spatiotemporal structure of wide jams.

According to the empirical observation of highway traffic, inside wide moving jams there is a complex spatiotemporal structure: jam is not compact and relatively large values of the time and the distance headway are visible. We present a cellular automata model by introducing "jam headway" and "jammed status" to simulate that complex structure. Using computer simulations, the fundamental diagram, the space-time plots, the time series of the density in the jams, and the 1-min average data of this model are analyzed. It is shown that compared to other existing models, this model can display the experimental characteristics of the wide moving jams.

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PubMed2002

Cellular automata model simulating traffic interactions between on-ramp and main road.

In this paper, we study the on-ramp system using the cellular automata traffic flow model. Different from previous works, we consider not only the influence of the on-ramp flow on the main road but also the opposite influence. The update rules are given in detail and the concept of priority is introduced. The numerical simulations are carried out and the phase diagram is presented. Two different types of phase diagram are distinguished and the currents of the on-ramp system are discussed.

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