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A thermodynamic theory is formulated to describe the phase transition and critical phenomena in pedestrian flow. Based on the extended lattice hydrodynamic pedestrian model taking the interaction of the next--nearest--neighbor persons into account, the time-dependent Ginzburg--Landau (TDGL) equation is derived to describe the pedestrian flow near the critical point through the nonlinear analysis method. The corresponding two solutions, the uniform and the kink solutions, are given. The coexisting curve, spinodal line, and critical point are obtained by the first and second derivatives of the thermodynamic potential. [ABSTRACT FROM AUTHOR]

Based on the full velocity difference model, Jiang et al. put forward the speed gradient model through the micro--macro linkage (Jiang R, Wu Q S and Zhu Z J 2001 Chin. Sci. Bull. 46 345 and Jiang R, Wu Q S and Zhu Z J 2002 Trans. Res. B 36 405). In this paper, the Taylor expansion is adopted to modify the model. The backward travel problem is overcome by our model, which exists in many higher-order continuum models. The neutral stability condition of the model is obtained through the linear stability analysis. Nonlinear analysis shows clearly that the density fluctuation in traffic flow leads to a variety of density waves. Moreover, the Korteweg-de Vries--Burgers (KdV--Burgers) equation is derived to describe the traffic flow near the neutral stability line and the corresponding solution for traffic density wave is derived. The numerical simulation is carried out to investigate the local cluster effects. The results are consistent with the realistic traffic flow and also further verify the results of nonlinear analysis. [ABSTRACT FROM AUTHOR]

A generalized Fisher equation (GFE) relates the time derivative of the average of the intrinsic rate of growth to its variance. The exact mathematical result of the GFE has been widely used in population dynamics and genetics, where it originated. Many researchers have studied the numerical solutions of the GFE, up to now. In this paper, we introduce an element-free Galerkin (EFG) method based on the moving least-square approximation to approximate positive solutions of the GFE from population dynamics. Compared with other numerical methods, the EFG method for the GFE needs only scattered nodes instead of meshing the domain of the problem. The Galerkin weak form is used to obtain the discrete equations, and the essential boundary conditions are enforced by the penalty method. In comparison with the traditional method, numerical solutions show that the new method has higher accuracy and better convergence. Several numerical examples are presented to demonstrate the effectiveness of the method. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the generalized Camassa and Holm (CH) equation by the improved element-free Galerkin (IEFG) method. By employing the improved moving least-square (IMLS) approximation, we derive the formulas for the generalized CH equation with the IEFG method. A variational method is used to obtain the discrete equations, and the essential boundary conditions are enforced by the penalty method. Because there are fewer coefficients in the IMLS approximation than in the MLS approximation, and in the IEFG method, fewer nodes are selected in the entire domain than in the conventional EFG method, the IEFG method should result in a higher computing speed. The effectiveness of the IEFG method for the generalized CH equation is investigated by numerical examples in this paper. [ABSTRACT FROM AUTHOR]

In this paper, we analyse the equal width (EW) wave equation by using the mesh-free reproducing kernel particle Ritz (kp-Ritz) method. The mesh-free kernel particle estimate is employed to approximate the displacement field. A system of discrete equations is obtained through the application of the Ritz minimization procedure to the energy expressions. The effectiveness of the kp-Ritz method for the EW wave equation is investigated by numerical examples in this paper. [ABSTRACT FROM AUTHOR]

The element-free Galerkin (EFG) method is used in this paper to find the numerical solution to a regularized long-wave (RLW) equation. The Galerkin weak form is adopted to obtain the discrete equations, and the essential boundary conditions are imposed by the penalty method. The effectiveness of the EFG method of solving the RLW equation is investigated by two numerical examples in this paper. [ABSTRACT FROM AUTHOR]

This paper obtains the energy-spectrum and eigenstate corrections of two-mode Bose-Einstein condensates (BECs) coupled by quantum tunnelling by perturbation method in both strong and weak tunnelling regions. The population imbalance between two BECs are then studied in terms of the low-lying eigenstates which also characterize the intrinsic entanglement between the two-mode BECs. The strong parity effect in the weak tunnelling region is also investigated. [ABSTRACT FROM AUTHOR]

Within the framework of a color flux-tube model with a four-body confinement potential, the tetraquark states [cq][c¯q¯] (q = u or d) with I JPC = 01− − are systematically investigated. The numerical results indicate that states Y (4008), Y (4140), Y (4260), and Y (4360) can be uniformly described as tetraquark states [cq][c¯q¯] with n2S+1 LJ of 11 P1, 15 P1, 25 P1 and 15F1, respectively, in the color flux-tube model. They are compact three-dimensional spatial configurations similar to a rugby ball, higher orbital angular momentum L, more prolate. The four-body confinement interaction based on a color flux-tube picture should be responsible for the formation of those compact tetraquark states. [ABSTRACT FROM AUTHOR]

We have carried out quantum Monte Carlo (QMC) calculations to study the interlayer interaction in a boron nitride (BN) bilayer. The binding energy, 81 meV/2BN after finite-size corrections, was found to be larger than that obtained by density functional theory (DFT) with local density approximation, and smaller than those using van der Waals density functionals, both by considerable amounts. The QMC calculated interaction beyond the equilibrium interlayer separation was found to have a longer-range behavior than all the available DFT schemes. [ABSTRACT FROM AUTHOR]

A thermodynamic theory is formulated to describe the phase transition and critical phenomenon in traffic flow. Based on the two-velocity difference model, the time-dependent Ginzburg--Landau (TDGL) equation under certain condition is derived to describe the traffic flow near the critical point through the nonlinear analytical method. The corresponding two solutions, the uniform and the kink solutions, are given. The coexisting curve, spinodal line and critical point are obtained by the first and second derivatives of the thermodynamic potential. The modified Korteweg de Vries (mKdV) equation around the critical point is derived by using the reductive perturbation method and its kink--antikink solution is also obtained. The relation between the TDGL equation and the mKdV equation is shown. The simulation result is consistent with the nonlinear analytical result. [ABSTRACT FROM AUTHOR]

The element-free Galerkin (EFG) method for numerically solving the compound Korteweg--de Vries--Burgers (KdVB) equation is discussed in this paper. The Galerkin weak form is used to obtain the discrete equation and the essential boundary conditions are enforced by the penalty method. The effectiveness of the EFG method of solving the compound Korteweg--de Vries--Burgers (KdVB) equation is illustrated by three numerical examples. [ABSTRACT FROM AUTHOR]

Traffic congestion is related to various density waves, which might be described by the nonlinear wave equations, such as the Burgers, Korteweg-de-Vries (KdV) and modified Korteweg-de-Vries (mKdV) equations. In this paper, the mKdV equations of four different versions of lattice hydrodynamic models, which describe the kink-antikink soliton waves are derived by nonlinear analysis. Furthermore, the general solution is given, which is applied to solving a new model -- the lattice hydrodynamic model with bidirectional pedestrian flow. The result shows that this general solution is consistent with that given by previous work. [ABSTRACT FROM AUTHOR]

The present paper deals with the numerical solution of time-fractional partial differential equations using the element-free Galerkin (EFG) method, which is based on the moving least-square approximation. Compared with numerical methods based on meshes, the EFG method for time-fractional partial differential equations needs only scattered nodes instead of meshing the domain of the problem. It neither requires element connectivity nor suffers much degradation in accuracy when nodal arrangements are very irregular. In this method, the first-order time derivative is replaced by the Caputo fractional derivative of order α (0 < α ≤ 1). The Galerkin weak form is used to obtain the discrete equations, and the essential boundary conditions are enforced by the penalty method. Several numerical examples are presented and the results we obtained are in good agreement with the exact solutions. [ABSTRACT FROM AUTHOR]

The present paper deals with the numerical solution of the third-order nonlinear KdV equation using the elementfree Galerkin (EFG) method which is based on the moving least-squares approximation. A variational method is used to obtain discrete equations, and the essential boundary conditions are enforced by the penalty method. Compared with numerical methods based on mesh, the EFG method for KdV equations needs only scattered nodes instead of meshing the domain of the problem. It does not require any element connectivity and does not suffer much degradation in accuracy when nodal arrangements are very irregular. The effectiveness of the EFG method for the KdV equation is investigated by two numerical examples in this paper. [ABSTRACT FROM AUTHOR]

Based on the optimal velocity (OV) model, a new car-following model for traffic flow with the consideration of the driver's forecast effect (DFE) was proposed by Tang et al., which can be used to describe some complex traffic phenomena better. Using an asymptotic approximation between the headway and density, we obtain a new macro continuum version of the car-following model with the DFE. The linear stability theory is applied to derive the neutral stability condition. The Korteweg--de Vries equation near the neutral stability line is given by nonlinear analysis and the corresponding solution for the traffic density wave is derived. [ABSTRACT FROM AUTHOR]