Modern Physics Letters B

A general analysis for the d-wave pairing in two components fermion system. Two physical conditions which can induce mismatched Fermi surfaces are considered: (i) Fixed chemical potential asymmetry δμ and (ii) fixed fermion number asymmetry α. In case (i), the gapless quasiparticle excitation arises both in usual Bardeen–Cooper–Schrieffer (BCS) and Sarma state due to the angle-dependent pairing gap, and they should be distinguished by gap susceptibility κ_Δ rather than the constraint Δ < δμ. Meanwhile, the d-wave pairing can hold larger chemical potential asymmetry δμ than the s-wave pairing. In case (ii), we find the angle dependence of the d-wave pairing gap can enhance the superfluidity for large asymmetry at low temperature.

In this paper, we proposed a model for controlling the group velocity of the transmitted and reflected pulses in a slab medium doped by four-level quantum dot nanostructure. Here, an infrared signal field interacted by quantum dot nanostructure can affect the behavior of reflected and transmitted pulses. We show that in the presence and absence of infrared pulses, the other controllable parameters have essential roles for controlling the slow and fast light propagation through the medium. Moreover, we found that the simultaneous slow and fast light can be obtained for the transmitted and reflected pulses by infrared signal field. Our proposed model may be useful for ultrahigh density optical memories in quantum communication systems or in various fields of all-optical systems.

Based on the extended scalar nonlinear Schrödinger equation, the influences of pumping schemes on the properties of dissipative soliton are investigated theoretically in passively mode-locked ytterbium-doped fiber laser with positive dispersion cavity. Results show that, under the conditions of the same initial total gain, the dissipative solitons obtained in the backward pumping fiber laser have the narrowest spectral width, shortest pulse duration and highest pulse peak power for the forward, backward and bidirectional pumping schemes, moreover, the linear fitting degree of pulse chirp is lowest. With the same gain saturation energy, the pulse energies of the dissipative solitons are equal for three pumping schemes, but the differences of output spectra and temporal waveforms increase as the gain saturation energy increases.

The hydrodynamic stability analysis of viscous flow between rotating porous cylinder has been researched for a long time by many researchers. But little works have been carried out about the linear stability analysis of the two-phase suspension. When the radial flow is present, the linear hydrodynamic stability analysis of suspension has been carried out between rotating porous cylinder. We know that the continuous and Stokes equations cannot only solve the stability problem of the continuous fluid phase, but also solving the stability problem of the discontinuous particle phase. The stability equations from an eigenvalue problem that was solved by a numerical technique based on Wan's method. The results reveal that the radial Reynolds number have a great effect on the critical Taylor number in the suspension. In this paper, we also researched on how the critical Taylor number changes as the radius ratio η, the axial wave number k, the particle concentration and the circumferential direction wave number happen to change with the radial Reynolds number increasing range from -5 to 5. Thus, our research discovered the radial inflow and outflow have a stabilizing effect on the two-phase suspension and the circumferential direction wave number also has a stabilizing effect.

Ti_1-xMn_xO₂ (x = 0, 0.05) nanoparticles have been synthesized using chemically derived self-propagating combustion reaction method. X-ray diffraction studies demonstrate the formation of anatase phase of TiO₂ belonging to 141/amd space group in both samples without the formation of any impurity phase. The incorporation of 5 at.% Mn content does not produce any changes in crystal structure which reveals the exact substitution of Mn atoms at Ti sites. Some change in lattice parameters and crystallite size is observed in Mn-doped composition, attributed to the difference in ionic radii. The size of grains obtained using scanning electron micrographs shows the consistent trend with the crystallite size evaluated from X-ray diffraction analysis. Energy dispersive X-ray analysis confirms the incorporation of Mn content in TiO₂ structure. Ferromagnetic behavior detected only in Mn-doped TiO₂ composition correspond to the strong Mn d-shell contribution.

Studies have shown there are several process/geometry parameters affecting the mechanical properties of the carbon nanotubes/epoxy composites. The relationship between the response and process/geometry parameters is highly nonlinear and quite complicated. It is very valuable to have an accurate model to estimate the response under different process/geometry parameters. In this paper, the support vector regression (SVR) combined with particle swarm optimization (PSO) for its parameter optimization was employed to construct mathematical models for prediction of mechanical properties of the carbon nanotubes/epoxy composites according to an experimental data set. The leave-one-out cross-validation (LOOCV) test results by SVR models support that the generalization ability of SVR model is high enough. The statistical mean absolute percentage error for tensile strength, elongation and elastic modulus are 3.96%, 3.14% and 2.62%, the correlation coefficients (R²) achieve as high as 0.991, 0.990 and 0.997, respectively. This study suggests that the established SVR model can be used to accurately foresee the mechanical properties of carbon nanotubes/epoxy composites and can be used to optimize designing or controlling of the experimental process/geometry in practice.

An extended two-lane lattice model of traffic flow with consideration of the slope effect is proposed. The slope effect is reflected in both the maximal velocity and the relative current. The stability condition of the model is derived by applying the linear stability method. By using the nonlinear analysis method, we obtain the Korteweg–de Vries (KdV) equation near the neutral stability line and the modified Korteweg–de Vries (mKdV) equation near the critical point. The analytical and numerical results demonstrate that the stability of traffic flow is enhanced on the uphill but is weakened on the downhill when the slope angle increases.

A two-step quantum dialogue scheme is put forward with a class of three-qubit W state and quantum dense coding. Each W state can carry three bits of secret information and the measurement result is encrypted without information leakage. Furthermore, we utilize the entangle properties of W state and decoy photon checking technique to realize three-time channel detection, which can improve the efficiency and security of the scheme.