Modern Physics Letters B

Nonlinear optics plays a crucial part in the progress of laser-based technologies and optical science. In this paper, we investigate the three-coupled variable-coefficient nonlinear Schrödinger system, which describes the amplification or attenuation of the picosecond pulses in an inhomogeneous multicomponent optical fiber with different frequencies or polarizations. Based on the existing Lax pair, we construct the first-/second-order generalized Darboux transformations and obtain the second-order semirational rogue-wave solutions, which represent the slowly varying envelopes of optical modes, under a constraint among the fiber gain/loss, nonlinearity and group velocity dispersion. We obtain the influences of nonlinearity and group velocity dispersion: when the value of the nonlinearity increases, amplitudes of the second-order semirational rogue waves decrease and when the value of the group velocity dispersion increases, amplitudes of the second-order semirational rogue waves increase. Baseband modulation instability (MI) through the linear stability explanation is obtained. When the characteristic roots have the negative imaginary parts, the system appears the baseband MI. When the MI occurs, it is of baseband type. With the positive parts, however, there is no MI occurring.

In this paper, the influence of imprecise quantum measurement on remote state preparation scheme is investigated. By analyzing the measurement parameters and corresponding errors, we obtain the evolution of output state in the process of remote state preparation. In terms of the fidelity of initial state and output state, the influence of imprecise quantum measurement is discussed. The results of this paper have the reference value for the selection of measurement basis when the quantum measurement on remote state preparation is imprecise.

In this paper, we use the Hirota bilinear method to find the $N$-soliton solution of a $(3+1)$-dimensional generalized Kadovtsev–Petviashvili (KP) equation. Then, we obtain the $T$-order breathers of the equation, and combine the long-wave limit method to give the $M$-order lumps. Resorting to the extended homoclinic test technique, we obtain the breather-kink solutions for the equation. Last, the interaction solution composed of the $K$-soliton solution, $T$-breathers, and $M$-lumps for the $(3+1)$-dimensional generalized KP equation is constructed.

In the past decade, the number of cars in China has significantly raised, but the traffic jam spree problem has brought great inconvenience to people’s travel. Accurate and efficient traffic flow prediction, as the core of Intelligent Traffic System (ITS), can effectively solve the problems of traffic travel and management. The existing short-term traffic flow prediction researches mainly use the shallow model method, so they cannot fully reflect the traffic flow characteristics. Therefore, this paper proposed a short-term traffic flow prediction method based on one-dimensional convolution neural network and long short-term memory (1DCNN-LSTM). The spatial information in traffic data is obtained by 1DCNN, and then the time information in traffic data is obtained by LSTM. After that, the space-time features of the traffic flow are used as regression predictions, which are input into the Fully-Connected Layer. In the end, the corresponding prediction results of the current input are calculated. In the past, most of the researches are based on survey data or virtual data, lacking authenticity. In this paper, real data will be used for research. The data are provided by OpenITS open data platform. Finally, the proposed method is compared with other road forecasting models. The results show that the structure of 1DCNN-LSTM can further improve the prediction accuracy.

We fabricated few-layered MoSe₂ nanosheets via the simple ultrasonic-assisted liquid phase exfoliation (UALPE) method. Typical characterizations and testing were exploited to confirm the nonlinear absorption properties of MoSe₂ nanoflakes. A passively Q-switched Nd:YVO₄ laser emitting 1 $\mu$m wavelength was demonstrated with the as-prepared MoSe₂ saturable absorber (SA). The stable pulses were generated with a maximum output power of 215 mW and a shortest pulse width of 192 ns. The experimental data provided a solid base for the photonics applications of MoSe₂ nanomaterials.

We calculate the critical exponents of the threshold singularity for the spectral density of the XXZ-spin chain at zero magnetic field for the lower threshold. We show that the corresponding phase shifts are momentum independent and coincide with predictions of the effective mobile impurity Hamiltonian approach.

At present, metal hydrides are considered highly promising materials for phonon-mediated superconductors that exhibit high values of the critical temperature. In the present study, the superconducting properties of the compressed selenium hydride in its simplest form (HSe) are analyzed, toward quantitative characterization of this phase. By using the state-of-art Migdal-Eliashberg formalism, it is shown that the critical temperature in this material is relatively high ($T_c=42.65$K) and surpasses the level of magnesium diboride superconductor, assuming that the Coulomb pseudopotential takes value of $0.1$. Moreover, the employed theoretical model allows us to characterize other pivotal thermodynamic properties such as the superconducting band gap, the free energy, the specific heat, and the critical magnetic field. In what follows, it is shown that the characteristic thermodynamic ratios for the aforementioned parameters differ from the predictions of the Bardeen-Cooper-Schrieffer theory. As a result, we argue that strong-coupling and retardation effects play important role in the discussed superconducting state, which cannot be described within the weak-coupling regime.

${\mathrm{\text{Sr}}}_{1-3x/2}{\mathrm{\text{La}}}_x{\mathrm{\text{TiO}}}_3$ (SLTO) ceramics ($x$ = 0.05, 0.10, 0.15) were prepared with giant dielectric constant by the traditional solid-state method at 1350${}^{\circ }$C. The temperature dependence of the dielectric constant was obtained at the temperature ranging from 29${}^{\circ }$C to 500${}^{\circ }$C and the frequency ranging from 2 kHz to 2 MHz. Two sets of relaxation peaks appear in the low temperature (region I) and the high temperature (region II), respectively. For region I, we conclude that the relaxation behavior is related to the oxygen vacancy migration. For region II, the two relaxation processes are caused by grain boundary for high frequency and Sr or Ti defects at grain interior for low frequency. With the doping amount reaching 0.15, the relaxation peaks disappear and become a common phase transition because of the aggravation of lattice distortion. These possible physical mechanisms of two sets of relaxation peaks are briefly discussed.

In this study, substitution effects of group 4 elements in Fe₂TiSn thermoelectric material are studied by using density functional theory (DFT) and semi-classical Boltzmann transport theory. All of the substitution elements showed the most thermodynamic preference for the Sn site, and these substitutions for Fe₂TiSn did not give much influence in the stability and mechanical property of Fe₂TiSn. e₂TiSn${}_{0.75}$Pb${}_{0.25}$, and thermoelectric calculations showed the prominence of $n$-type on $p$-type dopingin these materials. The highest Seebeck coefficients of these compounds were −148, −228, −165 and −120 $\mu$V/K for $n$-type of Fe₂TiSn, Fe₂TiSn${}_{0.75}$Si${}_{0.25}$, Fe₂TiSn${}_{0.75}$Ge${}_{0.25}$ and Fe₂TiSn${}_{0.75}$Pb${}_{0.25}$, respectively. The results showed that Si and Ge partial substitutions for Fe₂TiSn could be the effective methods to enhance the thermoelectric property, and the maximum dimensionless figure of merit (ZT) at room temperature reached about 0.7 ($6.09\times 10^{20}$cm${}^{-3}$ $n$-type doping concentration) in Fe₂TiSn${}_{0.75}$Si${}_{0.25}$ and 0.6 ($8.99\times 10^{20}$cm${}^{-3}$ $n$-type doping concentration) in Fe₂TiSn${}_{0.75}$Ge${}_{0.25}$.

In this paper, dynamic effective parameters of mass-type and stiffness-type bilayer perforated thin-plate acoustic metamaterials (MBPM and SBPM) are investigated by simulations and experiments. Dynamic effective parameters are calculated by the retrieval method, and formation mechanisms of special effective parameters are analyzed by simulated fields. Divergent effective parameters are produced by anti-resonances of coupled perforations or coupled perforated thin-plates, zero effective parameters are produced by resonances of coupled perforated thin-plates. The impacts of perforation parameters on dynamic effective parameters for symmetric and asymmetric BPMs are systemically studied, the simulated and experimental results both show that variation trends of resonance and anti-resonance frequencies of mass-type bilayer perforated thin-plate acoustic metamaterial (MBPM) are different from stiffness-type bilayer perforated thin-plate acoustic metamaterial (SBPM), because perforations mainly change system mass in MBPM and system stiffness in SBPM, respectively. Dynamic effective parameters are bi-anisotropic in asymmetric BPM, and doubly negative effective parameters are achieved by coupled perforations when plan wave normal incident from the side with smaller perforation parameters. A modified retrieval method is proposed to calculate unified effective parameters for the asymmetric BPM, and the unified effective parameters equal to averaged effective parameters of two symmetric BPMs. This work systematically studies dynamic effective parameters of bilayer perforated structures, which has a great guiding significance in design of perforated acoustic devices.

Three-dimensional (3D) unsteady Reynolds-averaged Navier–Stokes (URANS) simulations are conducted to investigate the blade load and internal flow field for a low specific centrifugal pump operating as a turbine (PAT). Validation and grid independence of the simulation method are performed and ensured. A thorough inspection to flow variables in terms of pressure and radial velocity as well as circumferential velocity at strong rotor–stator interaction region is performed. Unsteady performance characteristics in terms of head and shaft power as well as transient blade loads are evaluated to assess the unsteady PAT performance. Significant decreasing of the blade load is revealed when impeller passage passes the volute tongue and associated with the strong vortex close to passage suction side caused by the sharp angle of suction side trailing edge with a discernible flow incidence angle. High negative radial velocity in the region close to suction side is originated from the vortex inducing velocity at the blade suction side and a high pressure gradient in the trailing edge region. The decrease of blade load is caused by periodical development and restriction of the vortex with an impeller passage passing tongue and a subsequent pressure variation on suction side that leads to temporally decreased blade loading. High positive radial velocity in pressure side region is originated from the blocking effect from the strong vortex at suction side, leading to the generation of a relatively weaker vortex fluctuating with impeller rotation at pressure side. That is the source of pressure variation on pressure side, contributing to the blade loading variation. These results provide a detailed insight into the complex overload flow field that might be utilized for an improved PAT design.

The X-ray diffraction (XRD) spectrum of the nano-ZrO₂ compound was drawn, the crystal structure was determined at room temperature and under normal conditions. Radiation-thermal decomposition of water on nanosized ZrO₂ in the temperature range of $T=300$–673 K has been studied by Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. It has been shown that nanosized zirconium dioxide adsorbs water via the molecular and dissociative mechanisms. Intermediate products of the radiation-induced heterogeneous decomposition of water, namely, the molecular oxygen and hydrogen peroxide radical ions, zirconium hydride, and hydroxyl radicals have been detected. A comparative analysis of changes in the absorption bands (ABs) of molecular water and surface hydroxyl groups with temperature has been conducted, and the stimulating role of radiation in the radiation-thermal process of water decomposition has been revealed. With the participation of nano-ZrO₂ during the radiation-heterogeneous decomposition of water to reveal the role of unbalanced cargo carriers that play the role of energy carriers under the influence of gamma-quantities in nano-ZrO₂ and nano-${\mathrm{\text{ZrO}}}_2+{\mathrm{\text{H}}}_2\mathrm{\text{O}}$ systems paramagnetic centers, their origin and acquisition kinetics learned by the EPR method.

This paper studies the Biswas–Arshed model that compensates for the group velocity dispersion (GVD) by the dispersion of time and space. When the GVD and non-linearity are very small, the propagation patterns of the model are given by the complete discriminant system for polynomial method. Based on the results, under the specific parameters, we analyze the soliton transmission dynamic.

In this paper, the thermal effect on wave dispersion characteristic induced by the spinning and longitudinal motions in the viscoelastic carbon nanotubes (CNTs) conveying fluid is presented. Hamilton’s principle is utilized to derive the governing equation of this nanotube based on the non-local strain gradient and Euler–Bernoulli beam theories. Then, the dispersion solution is found by using the Naiver method. Based on this, the influences of the spinning and longitudinal motion velocities, structural damping, temperature and flow velocity on dispersion relation of the nanotubes are discussed according to numerical simulation. In view of the results of numerical examples, some interesting conclusions can be drawn. The existence of spinning motion leads to the coupling between the vibration in the $y$ and $z$ directions, which induces that the first-order transverse wave frequency increases/decreases for small/large wave number and the second-order one increases. The important solutions presented in the work will provide the useful information for the designation of the nanotubes conveying fluid with the spinning and longitudinal motion.

In this paper, Dirac point method is used to study the interface state of one-dimensional photonic crystal heterojunction ${[{(AB)}_m{(CD)}_m]}_n$ containing dispersive materials GaAs. We found that the energy levels of the interface states satisfy a simple sinusoidal function. We investigate the variation of the energy levels of the interface states with the incident angle, it is found that these interface states move toward high-frequency with the increase of the incident angle. At the same time, it is found that there is an extra localized band and it is further proved that the extra band corresponds to the defect band, and the energy levels of the defect band possess the same behavior with those of interface states.

The rapid adoption of sensor technology has upgraded the vehicular communication capacity, which enables the drivers to predict the traffic state (e.g. headway variation tendency (HVT)) based on the current traffic information. Meanwhile, in practice, the drivers would exhibit bounded rationality behavior in that they often perceive and respond to acceleration/deceleration only when the headway variation exceeds a certain threshold. The collective effect may greatly affect the driving behavior and traffic flow performance. In this study, we innovatively model the traffic flow macroscopically considering HVT and bounded rationality effect in the context of continuum model. Based on the linear stability theory, the stability condition of the above model is obtained. The KdV-Burgers equation of the model is derived to describe traffic jam propagation mechanism near the neutral stability line by applying the reductive perturbation method in nonlinear stability analysis. Results show that the HVT and bounded rationality behavior have a great impact on the traffic congestion and energy consumption.