Modern Physics Letters B

We consider a gas mixture consisting of spinless fermions and bosons in one dimension interacting via a repulsive $\delta$-function potential. Bosons and fermions are assumed to have equal masses and the interaction strength between bosons and among bosons and fermions is the same. Using the Bethe ansatz solution of the model, we study the ground state properties, the dressed energy potentials for the two bands of rapidities, the elementary particle and hole excitations, the thermodynamics, the finite size corrections to the ground state energy leading to the conformal towers, and the asymptotic behavior at large distances of some relevant correlation functions. The low-energy excitations of the system form a two-component Luttinger liquid. In an elongated optical trap the gas phase separates as a function of the distance from the center of the trap.

In this work, we have investigated theoretically the effects of applied electric field on the linear and nonlinear optical properties in a GaN/Al${}_x$Ga${}_{1-x}$N double inverse parabolic quantum well for different Al concentrations at the well center. Our calculations are based on the potential morphing method in the effective mass approximation. The systematic theoretical investigation contains results with all possible combinations of the involved parameters, such as quantum well width, quantum barrier width, Al concentration at each well center and magnitude of the external electric field. Our results show that the electric fields strengths, the parameter of nanostructure and incident optical intensity have a great effect on the optical characteristics of these nanostructures. Thus, the absorption coefficients which can be suitable for great performance optical modulators and multiple infrared optical device applications can be easily obtained by tuning the external electric field value and the Al concentration at the well center.

This paper studies the effect on the existing railway which is made by the train with 216 km/h high-speed when running across over the existing railway. The influence on the railway carrying capacity which is made by the transportation organization mode of the existing railway is analyzed under different parking modes of high-speed trains as well. In order to further study the departure intervals of the train, the average speed and the delay of the train, an automata model under these four-aspects is established. The results of the research in this paper could serve as the theoretical references to the newly built high-speed railways.

In this paper, electromagnetically induced transparency (EIT) is investigated in a GaAs spherical quantum dot (SQD) with central potential in presence of spherical metallic nanoparticle (SMNP). Solving the Schrödinger equation in effective mass, eigenfunctions and eigenvalues of SQD are obtained. By using the obtained eigenfunctions and eigenvalues, the susceptibility of SQD is found. In addition, dependence of EIT on radius of SQD and SMNP, distance between SMNP and SQD and Rabi and probe frequencies are investigated.

Under investigation in this paper is a (2+1)-dimensional B-type Kadomtsev–Petviashvili equation for the shallow water wave in a fluid or electrostatic wave potential in a plasma. Bilinear form, Bäcklund transformation and Lax pair are derived based on the binary Bell polynomials. Multi-soliton solutions are constructed via the Hirota’s method. Propagation and interaction of the solitons are illustrated graphically: (i) Through the asymptotic analysis, elastic and inelastic interactions between the two solitons are discussed analytically and graphically, respectively. The elastic interaction, amplitudes, velocities and shapes of the two solitons remain unchanged except for a phase shift. However, in the area of the inelastic interaction, amplitudes of the two solitons have a linear superposition. (ii) Elastic interactions among the three solitons indicate that the properties of the elastic interactions among the three solitons are similar to those between the two solitons. Moreover, oblique and overtaking interactions between the two solitons are displayed. Oblique interactions among the three solitons and interactions among the two parallel solitons and a single one are presented as well. (iii) Inelastic–elastic interactions imply that the interaction between the inelastic region and another one is elastic.

Under investigation in this paper is a (3 + 1)-dimensional generalized nonlinear Schrödinger equation with the distributed coefficients for the spatiotemporal optical solitons or light bullets. Through the symbolic computation and Hirota method, one- and two-soliton solutions are derived. We also present the Bäcklund transformation, through which we derive the soliton solutions. When the gain/loss coefficient is the monotonically decreasing function for the propagation coordinate $z$, amplitude for the spatiotemporal optical soliton or light bullet decreases along $z$, while when the gain/loss coefficient is the monotonically increasing function for $z$, amplitude for the spatiotemporal optical soliton or light bullet increases along $z$. Directions of the solitons are different because the signs of imaginary parts of the frequencies are adverse. Based on the two-soliton solutions, elastic and inelastic collisions between the two spatiotemporal optical solitons or light bullets are derived under different conditions presented in the paper.

By analyzing the relationship among the heat penetration depth, measurement frequency and detector characteristic parameters, a simple and practical $3\omega$ slope comparative method has been proposed. The corresponding measurement system for measuring the thermal properties of fluids and powder materials was established and verified using several specimens with known thermophysical parameters, such as alcohol, distilled water, and air. Compared to the two-dimensional model, the data processing of the method is relatively simple and quick. Due to the elimination of errors introduced by the detector parameter measurement, the measurement accuracy of the method is higher than the conventional one-dimensional model. By using an appropriate frequency range, the new method is time saving and convenient for measuring the thermal conductivity of fluids and powders with low thermal conductivity. Based on the analysis, the effective thermal conductivity of nano-SiO₂ powder is accurately determined.

Various car-following models (CMs) have been developed to capture the complex characteristics of microscopic traffic flow, among which the coupled map CM can better reveal and reflect various phenomena of practical traffic flow. Capacity change at bottleneck contributes to high-density traffic flow upstream the bottleneck and contains very complex dynamic behavior. In this paper, we analyze the effect of speed bottleneck on the spatial-temporal evolution characteristics of traffic flow, and propose a method to reduce traffic congestion with the feedback control signal based on CM. Simulation results highlight the potential of using the feedback signal to control the stop-and-go wave and furthermore to alleviate the traffic congestion effectively.

Aiming at the increasing demand of the diversification services and flexible bandwidth allocation of the future access networks, a flexible passive optical network (PON) scheme combining time and wavelength division multiplexing (TWDM) with point-to-point wavelength division multiplexing (PtP WDM) overlay is proposed for the next-generation optical access networks in this paper. A novel software-defined optical distribution network (ODN) structure is designed based on wavelength selective switches (WSS), which can implement wavelength and bandwidth dynamical allocations and suits for the bursty traffic. The experimental results reveal that the TWDM-PON can provide 40 Gb/s downstream and 10 Gb/s upstream data transmission, while the PtP WDM-PON can support 10 GHz point-to-point dedicated bandwidth as the overlay complement system. The wavelengths of the TWDM-PON and PtP WDM-PON are allocated dynamically based on WSS, which verifies the feasibility of the proposed structure.

Eight turbulence models frequently used in aerodynamics have been employed in the detailed numerical investigations for transonic flows in the Sajben diffuser, to assess the predictive capabilities of the turbulence models for shock wave/turbulent boundary layer interactions (SWTBLI) in internal flows. The eight turbulence models include: the Spalart–Allmaras model, the standard $k-𝜀$ model, the RNG $k-𝜀$ model, the realizable $k-𝜀$ model, the standard $k-\omega$ model, the SST $k-\omega$ model, the $\overline{v^2}-f$ model and the Reynolds stress model. The performance of the different turbulence models adopted has been systematically assessed by comparing the numerical results with the available experimental data. The comparisons show that the predictive performance becomes worse as the shock wave becomes stronger. The $\overline{v^2}-f$ model and the SST $k-\omega$ model perform much better than other models, and the SST $k-\omega$ model predicts a little better than the $\overline{v^2}-f$ model for pressure on walls and velocity profile, whereas the $\overline{v^2}-f$ model predicts a little better than the SST $k-\omega$ model for separation location, reattachment location and separation length for strong shock case.