Modern Physics Letters B

Under investigation in this paper is a (3+1)-dimensional generalized Kadomtsev–Petviashvili equation, which describes the long water waves and small-amplitude surface waves with the weak nonlinearity, weak dispersion and weak perturbation in a fluid. Via the Hirota method and symbolic computation, the lump wave, breather wave and rogue wave solutions are obtained. We graphically present the lump waves under the influence of the dispersion effect, nonlinearity effect, disturbed wave velocity effects and perturbed effects: Decreasing value of the dispersion effect can lead to the range of the lump wave decreases, but has no effect on the amplitude. When the value of the nonlinearity effect or disturbed wave velocity effects increases respectively, lump wave’s amplitude decreases but lump wave’s location keeps unchanged. Amplitudes of the lump waves are independent of the perturbed effects. Breather waves and rogue waves are displayed: Rogue waves emerge when the periods of the breather waves go to the infinity. When the value of the dispersion effect decreases, range of the rogue wave increases. When the value of the nonlinearity effect or disturbed wave velocity effects decreases respectively, rogue wave’s amplitude decreases. Value changes of the perturbed effects cannot influence the rogue wave.

Highly n-doped Ge on Si has been demonstrated to be a promising candidate for the compatible light source with silicon technology. In the in-situ n-doping process of Ge epilayers, the active concentration is limited below $2\times 10^{19}{\mathrm{\text{cm}}}^{-3}$ due to low solubility of dopant element in Ge matrix. Many dopant atoms are incorporated in the interstitial sites instead of substitution sites. We present a new approach to increase the electron concentration by adding carbon elements into P-doped Ge epilayers. A gain of PL intensity has been obtained with a factor of 2. The crystalline quality of the Ge film is also investigated owing to using a reflection high-energy electron diffraction (RHEED) apparatus and high-resolution transmission electron microscopy (HR-TEM). Phosphorus dopant is incorporated into Ge epilayers from specific GaP solid source.

In this paper, we study the electron acceleration by a circularly polarized electromagnetic wave propagating through plasma in the presence of a periodic and an axial guide magnetic field. A numerical calculation in MATLAB software was developed by employing the fourth-order Runge–Kutta method for studying the electron energy and electron trajectory in plasma medium. The equations governing the electron momentum and energy which describe electron acceleration by a circularly polarized laser pulse have been obtained. It is shown that by choosing an appropriate wiggler field frequency at short distances, the electron retains an adequate amount of energy. In addition, it is found that due to the simultaneous existence of the wiggler field and field of laser pulse and their combined effects, the electron in the direction of the laser pulse propagating, turns around and subsequently, the electron transverse momentum increases and as a result the electron escapes from the laser pulse near the laser pulse peak. Furthermore, it is seen that by increasing the laser intensity, the electron energy decreases and by decreasing to an appropriate value while employing a wiggler magnetic field, a higher peak of energy is gained.

The Fe–Ni–P matrix composites reinforced with carbon nanotubes (CNTs) were prepared by means of liquid phase sintering at 950${}^{\circ }$C. The effects of the mass fraction of CNTs on the microstructures and properties of the composites were investigated. It is noteworthy that the structures of CNTs were hardly damaged during the sintering process via evaluation of microstructures on as-sintered composites. The strength and ductility increased gradually with the increase of CNT content while the saturation magnetization decreased gradually. The sample containing 1 wt.% CNTs showed a good combination of a compression ratio of 60% and a compressive strength of approximately 3800 MPa, which indicated its potential application in modern power generation systems.

We report a graphene-based tunable ultra-narrowband mid-infrared filter which can be tuned from 4.45122 $\mu$m to 4.44675 $\mu$m by tuning the Fermi level from 0.2 eV to 0.6 eV. Furthermore, the reflection bandwidth is less than 0.2 nm and the reflection rate is more than 0.55. The ultra-narrowband filter is designed based on the guided-mode resonance (GMR) effect. The shift of reflection peak is mainly caused by the change of the real part of the graphene’s permittivity. This tunable ultra-narrowband mid-infrared filter can be applied in the mid-infrared microscopy.

Recycling noise is a kind of more common noise. The nonlinear dynamic system can be controlled by adjusting its parameters. However, so far, the effect of recycling noise on tri-stable dynamic system has not been reported. In this paper, stochastic P-bifurcations in tri-stable Duffing–Van der Pol oscillator induced by additive recycling noise are investigated. Firstly, the stationary probability density function is derived using stochastic averaging method. Then, the general expression of the critical parameter conditions of stochastic P-bifurcation is given by the singularity theory. The stationary probability density of response amplitude in different parameter areas are also shown, which is verified by Monte Carlo numerical simulation. Based on these results, the influence of related parameters of recycling noise and damping coefficient on the stochastic P-bifurcation is studied. The result shows that the critical parameter of bifurcation can be changed by adjusting the delay time and fraction coefficient of the recycling noise. It has also been found that the stationary probability density and stochastic bifurcation show a periodic dependence on the delay time.

This paper reports structural and electrical characteristics of F-doped $\beta$V₂O₅ thin films of different F concentrations. The films were analyzed by X-ray diffraction. It was found that F-doping in vanadium pentoxide affects the crystallinity of the samples. The SEM images have shown that by increasing the F-doping level, the size of the nanobelt increases. Electrical measurements indicated that the F-doping in $\beta$V₂O₅ makes the temperature of phase transition change from semiconductor to metallic phase.

We study the the high-temperature thermodynamic properties of the q-deformed fermion gas model by taking into account of the size effect of the gas particles. Starting from the logarithm of the grand partition function of the model, we calculate several thermodynamic functions of the model such as internal energy, entropy, and Helmholtz free energy by means of the deformation parameter q. Furthermore, the influences of the fermionic q-deformation on the thermosize effect in the confined deformed quantum gas systems such as the Seebeck-like and Peltier-like thermosize effects are discussed. Especially, we focus on the absorbed or released heat of the model in the Peltier-like thermosize effect. In the light of the results obtained in this work, we can conclude that the present q-deformed fermion model can be used to desing the new types of the micro-/nano-scaled quantum heat engines.

YOYO-1 intercalation leads to the reduction of twist rigidity, unwinding of DNA, elongation of DNA contour length and YOYO-1 concentration-dependent persistence length, until now few works identified their roles in determining the topological states of circular DNA. Based on the convolution of the writhe distribution of circular DNA obtained by using Monte Carlo simulation and the twist distribution, effects of YOYO-1 intercalation on the linking number distribution of circular DNA are predicted and identified. YOYO-1 intercalation leads to larger fluctuation, but not to the obvious enlargement of the writhe distribution, so that the variance of the linking number distribution mainly depends on the variance of the twist distribution. The unwinding angle contributes to the drifting of the linking number distribution away from the original equilibrium value of zero and has no effects on the variance of the linking number distribution, converse to the roles of the reduced twist rigidity in the linking number distribution. Furthermore, the method used in the work can be generalized to detect the effects of other intercalators on the topological states of circular DNA.

We study the performance of minimally nonlinear irreversible refrigerators which works between a hot and cold heat reservoir of constant temperatures $T_h$ and $T_c(<T_h)$, respectively. Applying optimization criterion $\dot{\mathrm{\Omega }}$ or $\chi$, we analyze the coefficient of performance (COP) at arbitrary value of $\chi$ or $\dot{\mathrm{\Omega }}$ and thus obtain the upper and lower bounds of the COP. Our results show that, for the optimized, tightly-coupled refrigerators, a small loss away from the maximum value of either $\chi$ or $\dot{\mathrm{\Omega }}$ figure of merit means a larger gain in the COP.

In this paper, a new lattice two-lane hydrodynamic model is proposed by considering the lane changing and the optimal current change with memory effect. The linear stability condition of the model is obtained through the linear stability analysis, which depends on both the lane-changing rate and the memory step. A modified Korteweg–de Vries (mKdV) equation is derived through nonlinear analysis to describe the propagating behavior of traffic density wave near the critical point. To verify the analytical findings, numerical simulation was carried out, which confirms that the optimal current change with memory of drivers and the memory step contribute to the stabilization of traffic flow, and that traffic congestion can be suppressed efficiently by taking the lane-changing behavior into account in the lattice model.

In this paper, using Lie symmetry method, we obtain some new exact traveling wave solutions of the Camassa–Holm–Degasperis–Procesi (CH–DP) equation. Some new bright and dark soliton solutions are obtained. Also, some new doubly periodic solutions in the form of Jacobi elliptic functions and Weierstrass elliptic functions are obtained.

We use the Fourier operator to transform a time-dependent mass quantum harmonic oscillator into a frequency-dependent one. Then we use Lewis–Ermakov invariants to solve the Schrödinger equation by using squeeze operators. Finally, we give two examples of time dependencies: quadratically and hyperbolically growing masses.

In this study, diamond thin films were deposited on tungsten carbide tools using surface-wave plasma-enhanced chemical vapor deposition (SWP-CVD). To eliminate the adverse effects of cobalt on the diamond deposition process, the cobalt was removed from the surface of the tools by etching with Murakami’s reagent for various times (30, 60, and 120 min). The cutting performance of the untreated and the diamond-coated WC tools was examined by performing cutting test on carbon fiber-reinforced plastic (CFRP). The results showed that all the diamond-coated tools exhibited great improvement on the durability and wear resistance compared to the uncoated one. In addition, the diamond-coated tool lift time is found to be proportional to the etching time. An increase more than twofold has been achieved when the etch time was increased from 30 min to 120 min.