A new cellular automaton model for urban two-way road networks

A new cellular automaton (CA) model is proposed to simulate traffic dynamics in urban two-way road network systems. The NaSch rule is adopted to represent vehicle movements on road sections. Two novel rules are proposed to move the vehicles in intersection areas, and an additional rule is developed to avoid the “gridlock” phenomenon. Simulation results show that the network fundamental diagram is very similar to that of road traffic flow. We found that the randomization probability and the maximum vehicle speed have significant impact on network traffic mobility for free-flow state. Their effect may be weak when the network is congested.

Optimization of the design of pre-signal system using improved cellular automaton

The pre-signal system can improve the efficiency of intersection approach under rational design. One of the main obstacles in optimizing the design of pre-signal system is that driving behaviors in the sorting area cannot be well evaluated. The NaSch model was modified by considering slow probability, turning-deceleration rules, and lane changing rules. It was calibrated with field observed data to explore the interactions among design parameters. The simulation results of the proposed model indicate that the length of sorting area, traffic demand, signal timing, and lane allocation are the most important influence factors. The recommendations of these design parameters are demonstrated. The findings of this paper can be foundations for the design of pre-signal system and show promising improvement in traffic mobility.

Characteristics of traffic flow at nonsignalized T-shaped intersection with U-turn movements

Most nonsignalized T-shaped intersections permit U-turn movements, which make the traffic conditions of intersection complex. In this paper, a new cellular automaton (CA) model is proposed to characterize the traffic flow at the intersection of this type. In present CA model, new rules are designed to avoid the conflicts among different directional vehicles and eliminate the gridlock. Two kinds of performance measures (i.e., flux and average control delay) for intersection are compared. The impacts of U-turn movements are analyzed under different initial conditions. Simulation results demonstrate that (i) the average control delay is more practical than flux in measuring the performance of intersection, (ii) U-turn movements increase the range and degree of high congestion, and (iii) U-turn movements on the different direction of main road have asymmetrical influences on the traffic conditions of intersection.

Surface force confinement cell for neutron reflectometry studies of complex fluids under nanoconfinement

In this paper, we describe the construction of a new neutron surface force confinement cell (NSFCC). The NSFCC is equipped with hydraulically powered in situ, temporally stable, force control system for simultaneous neutron reflectometry studies of nanoconfined complex fluid systems. Test measurements with deuterated toluene confined between two opposing diblock copolymer (polystyrene+poly 2-vinylpyridine) coated quartz substrates demonstrate the capabilities of the NSFCC. With increasing hydraulically applied force, a series of well-defined decreasing separations were observed from neutron reflectivity measurements. No noticeable changes in the hydraulic pressure used for controlling the surface separation were observed during the measurements, demonstrating the high stability of the apparatus. This newly designed NSFCC introduces a higher level of control for studies of confinement and consequent finite size effects on nanoscale structure in a variety of complex fluid and soft condensed matter systems.

Segment distributions of end-tethered polymers in a good solvent

We use confocal fluorescence microscopy to study the conformation of single DNA molecules end-tethered to a solid substrate. The segment distribution rho(z) measured for chains with contour lengths 15.4 microm <or= L <or= 59.4 microm as a function of the distance from the substrate can be scaled onto a master curve depending only on the scaled distance z/R(g), in quantitative agreement with theoretical predictions for end-tethered polymers in a good solvent. The scaling of the radius of gyration R(g) approximately L(0.57+/-0.05) shows the presence of excluded-volume interactions between the charged DNA segments. Independent measurements of R(g) from end-segment distributions are in good agreement with values obtained from the segment distributions and provide evidence that the radius of gyration of end-tethered chains in a good solvent is identical to that of the free chain.

Pack formation in cycling and orienteering

In cycling and orienteering competitions, competitors can become bunched into packs, which may mask an individual's true ability. Here we model this process with a view to determining when competitors' times are determined more by others than by their own ability. Our results may prove useful in helping to stage events so that pack formation can be avoided.

Molecular weight effects on chain pull-out fracture of reinforced polymeric interfaces

Using Brownian dynamics, we simulate the fracture of polymer interfaces reinforced by diblock connector chains. We consider the mushroom regime, where connector chains are grafted with low surface density, for the case of large pulling velocities. We find that for short chains the interface fracture toughness depends linearly on the degree of polymerization N of the connector chains, while for longer chains the dependence becomes N(3/2). Based on the geometry of the initial chain configuration, we propose a scaling argument that accounts for both short and long chain limits and the crossover between them.