International Journal of Modern Physics C

In this paper, the unsignalized T-shaped intersection is modeled by a cellular automata model. The main street and the minor street join at the intersection. As to the traffic flow is not controlled by traffic lights, conflict happens between the vehicles from minor street and that from main street. Two different crash avoiding rules are used to dispose the conflicts. In the first rule, the priorities are given to the driving-ahead vehicle and the vehicle on the main street. In the second rule, the vehicle that reaches the conflicting point earlier enters into the intersection. The flux on each lane depending on the inflow rates is studied in detail. The capacity of the system is also investigated. Our simulation results suggest that the two rules do not take the same effect on the capacity under different traffic conditions.

The relationship between thermal conductivity of porous material and fractal dimension is numerically simulated by using the finite element method. The solid matrix and pore space are generated randomly according to material porosity. Material parameters and element properties are changed by using ANSYS parameter design language. The effective thermal conductivity is derived according to thermal flux through some sections computed by FEM and Fourier heat transform law. The investigation shows that the effective thermal conductivity decreases with increasing porosity. The effective thermal conductivity will decrease exponentially with increasing fractal dimension of porosity space and increase exponentially with increasing fractal dimension of solid matrix.

We present a novel optimization method for an Ising like system suspended in a lattice with nonstatic defects. Depending on the size of the experimental probe the system spontaneously defines a defect free lattice where the control function can be optimized using conventional methods as Metropolis heuristics. We illustrate this method in a lattice with variable defects and show how the magnetization of the system depends on the spontaneous definition of the defect-free lattice. This approximation should be useful as a basis for the definition of systems of agents with imperfect coordination.

We explore the potential of parallel tempering as a combinatorial optimization method, applying it to the traveling salesman problem. We compare simulation results of parallel tempering with a benchmark implementation of simulated annealing, and study how different choices of parameters affect the relative performance of the two methods. We find that a straightforward implementation of parallel tempering can outperform simulated annealing in several crucial respects. When parameters are chosen appropriately, both methods yield close approximation to the actual minimum distance for an instance with 200 nodes. However, parallel tempering yields more consistently accurate results when a series of independent simulations are performed. Our results suggest that parallel tempering might offer a simple but powerful alternative to simulated annealing for combinatorial optimization problems.

A scheme is proposed for remotely preparing a class of three-particle GHZ states by using a Bell state and a three-qubit GHZ state as the quantum channel. In the scheme, a two-qubit collective state measurement is performed and the necessary classical communication cost is 0.25 cbit on average. In general, the target state can be successfully prepared with the probability 1/4. However, if the state belongs to some special classes, the preparation success probability can reach 0.5 or even 1 after consuming a little additional classical resource. Comparing with the recent scheme [Opt. Commun.281, 871 (2008)], the present scheme has some advantages, e.g., the simpler quantum joint measurement and the less classical resource consumption.

This paper investigates the effect of a linear adjustment of a search space size in genetic algorithm (GA) on the macroscopic statistical properties of population (such as the average fitness and the variance fitness of population). The equations of motion were derived for one-max problem that expressed the macroscopic statistical properties of population after the adjustment of a search space size. Analysis of a performance of GA that includes a computational cost and a quality of the optimal solution was made for linear and power laws of search space adjustment.

In this paper, adopting the initial load of a node j to be , where k_j is the degree of the node j and α is a tunable parameter that controls the strength of the initial load of a node, we propose a cascading model with a breakdown probability and explore cascading failures on a typical network, i.e., the Barabási–Albert (BA) network with scale-free property. Assume that a failed node leads only to a redistribution of the load passing through it to its neighboring nodes. According to the simulation results, we find that BA networks reach the strongest robustness level against cascading failures when α = 1 and the robustness of networks has a positive correlation with the average degree 〈k〉, not relating to the different breakdown probabilities. In addition, it is found that the robustness against cascading failures has an inversely proportional relationship with the breakdown probability of an overload node. Finally, the numerical simulations are verified by the theoretical analysis.

In this paper, firstly, the control problem for the chaos synchronization of discrete-time chaotic (hyperchaotic) systems with unknown parameters are considered. Next, backstepping control law is derived to make the error signals between drive 2D discrete-time chaotic system and response 2D discrete-time chaotic system with two uncertain parameters asymptotically synchronized. Finally, the approach is extended to the synchronization problem for 3D discrete-time chaotic system with two unknown parameters. Numerical simulations are presented to show the effectiveness of the proposed chaos synchronization scheme.

In this paper, the melting behaviors of the glass-like cluster Au₁₉ are calculated and analyzed by using standard microcanonical molecular-dynamics simulations. The calculated results show a multi-step melting process. The first stage involves the majority of the surface atoms (14 atoms). An interesting phenomenon is that the minority of the surface atoms (4 atoms) are still in a solid-like state. The second stage involves all of the surface atoms. But there are two sites where the atoms stay for a relatively long time. The third stage corresponds to the frequent isomerizations involving all the surface atoms. The final stage consists of isomerization transitions involving all of the atoms, including the central atom of the cluster. The unique melting processes lead to the unique features of the caloric curve, the root-mean-square bond-length fluctuation, and the heat capacity of the glass-like Au₁₉.

This paper presents methods of localization of mobile systems using recent Radio Frequency Identification (RFID) technology. We consider an indoor environment where RFID tags are implanted along the wall or in objects in the room. If the absolute position and orientation of a tag are read by an RF reader, a mobile system can estimate its location using the information saved in the tags. A reader-tag model is obtained through experiments in order to derive relative positions and orientations between an antenna and an RFID tag. To estimate the location, we propose two estimation methods. One uses a single RFID tag and the other uses multi-RFID tags. Experimental results show that the proposed methods can provide good performance for mobile system localization in an indoor environment.

The stability of the numerical schemes for anisotropic advection-diffusion equations derived from the lattice Boltzmann equation with the D2Q4 particle velocity model is analyzed through eigenvalue analysis of the amplification matrices of the scheme. Accuracy of the schemes is investigated by solving benchmark problems, and the LBM scheme is compared with traditional implicit schemes. Numerical experiments demonstrate that the LBM scheme produces stable numerical solutions close to the analytical solutions when the values of the relaxation parameters in x and y directions are greater than 1.9 and the Courant numbers satisfy the stability condition. Furthermore, the numerical solutions produced by the LBM scheme are more accurate than those of the Crank–Nicolson finite difference scheme for the case where the Courant numbers are set to be values close to the upper bound of the stability region of the scheme.

The radial part of Klein–Gordon equation is solved for the Woods–Saxon potential within the framework of an approximation to the centrifugal barrier. The bound states and the corresponding normalized eigenfunctions of the Woods–Saxon potential are computed by using the Nikiforov–Uvarov method. The results are consistent with the ones obtained in the case of generalized Woods–Saxon potential. The solutions of the Schrödinger equation by using the same approximation are also studied as a special case, and obtained the consistent results with the ones obtained before.