International Journal of Modern Physics B

In this paper, we studied the grain size and volume fraction change of $\alpha$-Fe(Si) nanocrystalline phase as a function of Cu, Mo and Si content in Fe${}_{74.5-x}$Cu${}_x$Mo₃Si${}_{13.5}$B₉, Fe${}_{76.5-y}$Cu₁Mo${}_y$Si${}_{13.5}$B₉, Fe${}_{73.5}$Cu₁Mo₃Si${}_z$B${}_{22.5-z}$, and also the annealing temperature and time in Fe${}_{73.5}$Cu₁Mo₃Si${}_{13.5}$B₉ alloy. Cu is an element promoting ultrafine structure and crystallization progresses, it causes the grain size of the $\alpha$-Fe(Si) phase to decrease suddenly, the volume fraction of $\alpha$-Fe(Si) phase to increase only by adding 0.5 at.% Cu. Also, Mo causes the grain size of $\alpha$-Fe(Si) phase to decrease like Cu, while suppressing the increase of the volume fraction of $\alpha$-Fe(Si) phase, Si has no little effect on the grain size of $\alpha$-Fe(Si) phase, diffuses into the inner part of $\alpha$-Fe(Si) phase upto Si 13.5 at.%, but suddenly increases grain size above Si 13.5 at.%. The microstructure of Fe${}_{73.5}$Cu₁Mo₃Si${}_{13.5}$B₉ alloy is nearly completed at 520${}^{\circ }$C for about 20 min, the grain size is approximately 13.8–14.1 nm, the volume fraction of $\alpha$-Fe(Si) phase is within 61–66%, initial permeability at 1 kHz is within 59,800–61,100.

We study the modification of low-temperature properties of quantum magnets such as magnetization, heat capacity, energy spectrum and densities of condensed and noncondensed quasiparticles (triplons) due to anisotropies in the framework of mean-field- based approach. We show that in contrast to exchange anisotropy (EA) interaction, Dzyaloshinsky–Moriya (DM) interaction modifies the physics dramatically. Particularly, it changes the sign of the anomalous density in the whole range of temperatures. Its critical behavior is slightly modified also by the EA. We have found that the shift of the critical temperature of phase transition (or crossover caused by DM interaction) is positive and significant. Using the experimental data on the magnetization of the compound TlCuCl₃, we have found optimal values for the strengths of EA and DM interactions. The spectrum of the energy of low lying excitations has also been investigated and found to develop a linear dispersion similar to Goldstone mode with a negligibly small anisotropy gap.

Development and demonstration of a new method for highly accurate forecasting of the hydrocarbon composition of oil based on determining the spectrum of its universal material constant–dielectric function, as by direct measurement using the method of spectroscopic ellipsometry, are today accepted as the world standard for determining the optical functions of any substance in a liquid or solid state, and by its quantum-mechanical calculation from first principles to complete coincidence with the measurement results. A methodology will be proposed for the complete description of any oil and the identification of it belonging to a particular oilfield. The methodology is not only universal and highly accurate, but also economical. In this work, we obtained several groups of fractions of crude oilsamples from different oil fields in Azerbaijan, which were accessed by spectroscopic ellipsometry over the 1.5–6.5 eV spectral range at room-temperature. Optical constants and dielectric function were obtained for massive samples of each substance and fractions. The proposed method is a complete dielectric fingerprint of oils for widespread use, including for environmental monitoring of oil-contaminated areas of the sea and land.

The traffic dynamics of complex networks is closely related to network structure. By changing network structure, the traffic dynamics behavior can be optimized. Faced with the network congestion problem, we focus on the relationship between network traffic capacity and its structure. The multilayer networks are studied, which are composed of high-speed and low-speed layers. A link rewiring strategy is proposed to change the low-speed layer structure and improve the network traffic capacity. Compared with the random link rewiring strategy, the purposeful link rewiring strategy can improve network traffic capacity. A large number of simulations are carried out under the effective traffic-flow assignment strategy to prove the effectiveness of the link rewiring strategy. This strategy improves packet transmission efficiency of low-speed layer, and reduces the average length of effective path, which indicates that adjustment of low-speed layer structure can improve traffic capacity of multilayer networks.

We have used a method for determining volume dependence of the Grüneisen parameter in the Lindemann law to study the pressure dependence of melting temperatures in case of 10 metals viz. Cu, Mg, Pb, Al, In, Cd, Zn, Au, Ag and Mn. The reciprocal gamma relationship has been used to estimate the values of Grüneisen parameters at different volumes. The results for melting temperatures of metals at high pressures obtained in this study using the Lindemann law of melting are compared with the available experimental data and also with the values calculated from the instability model based on a thermal equation of state. The analytical model used in this study is much simpler than the accurate DFT calculations and molecular dynamics.

This paper assumes that the particle jumps randomly (Guassian jumps) from one point to another along one of the imaginary lines inside the interactive medium. Since this study was done in the space, we consider that the position of the particle at any time $t$ has a multivariate distribution. The random waiting time of the particle for each Gaussian jump depends on its length. An identical set of programed nanosensors (with unit speed) were used to track this particle. Each line has a sensor that starts the tracking process from the origin. The existence of the necessary conditions which give the optimal search plan and the minimum expected value of the particle detection has been proven. This study is supported by a numerical example.

This paper studies Attilio Maccari (AM) system for some new solitary wave solutions. We used sub-ODE scheme to find kink shape, bell type, Weierstrass and Jacobi elliptic, hyperbolic, periodic and other solitary wave solutions under some constraint conditions. We will also present our results graphically in distinct dimensions.

This paper discusses the structural, electronic, magnetic, and half-metallic properties of half-Heusler alloy KCaB. First-principles calculation based on density functional theory is successfully used to determine properties at bulk and on the (111) and (001) surfaces of KCaB. KCaB is half-metallic ferromagnet with a magnetic moment of 1 ${\mu }_{\mathrm{\text{B}}}$ and an energy gap equal to 0.82 eV in the lower spin channel. The $n$-type doped exhibits higher Seebeck coefficient, electrical conductivity, thermal conductivity, and figure of merit than the $p$-type-doped KCaB at room-temperature 300 K. The half-metallic property is preserved in each of the ends Ca and B on the (111) surface and is lost in the ends K (111) and B and KCa (001) slab surface. The relaxation effect on the electronic spin states decreases the magnetic moment of some atoms on the end surface because the relaxation of the atomic sites is affected and the loss of the nearest neighbors affects exchange–correlation interactions. The surface end with Ca is more stable than the surface end with B on the (111) surface and can maintain the property of half metallic under relatively large stress.

In this paper, the dynamical behaviors of the FitzHugh–Nagumo (FHN) system with a memory trace, which has time-fractional derivatives, are investigated. For the case of a classical order, the constant input current can change the stability of the equilibrium point in a single FHN unit, and the equilibrium is unstable in a certain range of the current. A decrease of the order of the time-fractional derivative may lead to a linear reduction of the range and the appearance of a solution of mixed-mode oscillations, which consist of subthreshold small-amplitude oscillation and suprathreshold large-amplitude oscillation. In the parameter space of the input current and the fractional order, the region of existing the mixed-mode oscillation is linearly widened when the fractional order moves toward its small value. If a suprathreshold perturbation is periodically applied, there exist some obvious bands, on which the excited period is locked to the perturbation period according to some rational ratios. As a result, the bands can be narrowed by decreasing the value of fractional order and their location has a slight drift toward the small value of the perturbation period. In addition, the properties of solitary traveling waves and wave train solutions are also studied in the one-dimensional space. It is illustrated that the traveling pulse is wider for a smaller value of fractional order, and its velocity is larger. Further, some relations of wave trains have a great change when the value of the fractional order is changed.

In this paper, we propose a recursive Darboux transformation in a generalized form of a focusing vector Nonlinear Schrödinger Equation (NLSE) known as the Manakov System. We apply this generalized recursive Darboux transformation to the Lax-pairs of this system in view of generating the Nth-order vector generalization rogue wave solutions with a rule of iteration. We discuss from first- to three-order vector generalizations of rogue wave solutions while illustrating these features with some 3D, 2D graphical depictions. We illustrate a clear connection between higher-order rogue wave solutions and their free parameters for better understanding the physical phenomena described by the Manakov system