International Journal of Modern Physics B

Numerical electromagnetic field simulations of high-temperature superconductors (HTSC) bulk were carried out to calculate the magnetic force between the HTSC bulk and the permanent magnet railway (PMR). A 3D-modeling numerical calculation method is proposed using the finite element method. The model is formulated with the magnetic field vector (H-method). The resulting code was written with FORTRAN language. The electric field intensity E and the current density J constitutive relation of HTSC were described with E–J power law. The Kim macro-model is used to describe critical current density J_c of HTSC bulk. Two virtual HTSC bulks were used to solve the critical current density J_c anisotropic properties of HTSC materials. A superconducting levitation system composed of one HTSC bulk and PMR is successfully investigated using the proposed method. By this method, the influence of critical current density on magnetic levitation force of the superconducting levitation system is mathematically studied.

This investigation deals with the time-dependent flow of an incompressible viscous fluid bounded by an infinite plate. The fluid is electrically conducting under the influence of a transverse magnetic field. The plate moves with a time dependent velocity in its own plane. Both fluid and plate exhibit rigid body rotation with a constant angular velocity. The solutions for arbitrary velocity and magnetic field is presented through similarity and numerical approaches. It is found that rotation induces oscillations in the flow.

Carbon nanotubes have been the subject of extensive research during the past decade because of their exceptional properties. These tiny nanostructures have eventually paved their way into the exciting and promising field of organic electronics, which is expected to dominate the area of low cost and flexible electronics in the near future. We have prepared multiwall carbon nanotube (MWNT) and poly(3,4-ethylenedioxythiophene):poly(styrenesulphonic acid) (PEDOT:PSS) based nanocomposites using different concentrations of MWNTs. These nanocomposites have been characterized using SEM, AFM, absorption spectroscopy, and electrical characterization methods. The SEM micrographs clearly reveal that the nanotubes are quasi uniformly dispersed in huge quantities throughout the polymer matrix. They also show the wetting of the nanotubes by the polymer. It is observed that the solution processed MWNT–PEDOT:PSS nanocomposite based films exhibit improved, higher current, and lower turn-on voltage as compared to pure PEDOT:PSS based films. On the basis of percolation theory, a low electrical percolation threshold value of 0.1 wt% was obtained for this nanocomposite system, signifying the formation of a continuous conductive network at a very low MWNT concentration. The ease of fabrication of the nanocomposite (solution processed), higher current, lower turn-on voltage and low electrical percolation threshold value, make it an excellent candidate for flexible electronics applications, which will dominate the electronics scenario in the near future.

A plasmonic filter applied in visible regime is proposed. A method using discrete dipole approximation (DDA) to aid design parameters of rhombic Ag nanoparticle array is adopted for the filter design and optimization on the basis of computational numerical calculation. Influence of the particle parameters such as thickness, period and effective index of medium around the particles on the extinction spectrum is studied using the DDA-based computational analysis. The calculation results show that the thickness ranging from 35 to 45 nm and the period ranging from 350 to 560 nm are the better geometrical parameters of the rhombic Ag nanoparticle array. Considering the nano-fabrication condition, 40 nm thickness and 440 nm period were selected and fabricated using nanosphere lithography (NSL) technique. The experimental results demonstrated that the measured spectrum is basically in agreement with the theoretical spectrum derived by the DDA calculation.

Electron beam physical vapor deposition (EBPVD) is being used in coating components for many applications such as for producing nanostructures and integrated circuits (ICs) coating in electronic industry. In this work, copper was deposited on the SiO₂/p-type Si(100). Thin film characteristics are investigated by scanning electron microscopy and X-ray diffraction (XRD). Then oxidation behavior of deposits was evaluated by Dektak Surface Profiler and weight gain method at 200 and 300°C. Results showed that thin film copper deposited by EBPVD has better oxidation characteristics in comparison with copper foil.

We use symbolic dynamics to investigate the transfer of information between the dissipative coupled nonidentical oscillators exhibiting the generalized synchronization. It is found that the drive information is injected into the response state and stored reversely in it. Moreover, the injection and storage give new meanings to the conditional Lyapunov exponent from the view of the information.

The systems MgCuZnFe₂O₄ doped (0–0.6 wt% Ta) are prepared by the general ceramic method using the sintering temperature at 1200°C. The variations of the sintered density, lattice parameter, jump length of electrons, and initial permeability were studied. A maximum density was obtained at 1200°C during the preparation process. The electrical resistivity decreases with increasing tantalum (Ta) content upto 0.1 wt% and then increases for higher concentrations. The initial permeability and the change carries mobility increase upto 0.1 Ta and then decreases. The jump length decreases with enhancing Ta ions because the substitution of Ta ion with small size instead of Fe³⁺ at the A sites increase the concentration of iron ions at the B sites. The increase of the iron content causes the decrease of the jump length of electrons between Fe³⁺ and Fe²⁺. These improvements of the magnetic properties give some light about the importance of these compositions to be used in technology.

In this paper, the perturbed virial equations of state with temperature-dependent virial coefficients are constructed using the Carnahan–Starling (CS) hard sphere equation as reference. Considering the second virial coefficient, some critical properties are interaction-independent and the critical packing factor is in the range of that of real fluids. But the critical compressibility factor and the liquid–vapor equilibrium properties disagree with experiments. When both the second and the third virial coefficient are considered, the critical properties are interaction-dependent but are out of the range of experimental results of real fluids. As a conclusion, the fourth virial coefficients are required for further consideration.

In this paper we deal with the Fourier analysis of EXAFS data and illustrate this by a detailed analysis of the data for copper metal and copper complexes of Isoxezol series. Fourier analysis is useful in extracting distances and information about the phase shifts, the amplitudes, the Debye–Waller factors and the mean free paths. Here we have determined interatomic distances, mean square deviation and inelastic mean free path from Fourier transform of EXAFS data for copper metal and copper complexes of Isoxezol series.

A 3-field integrable lattice system with three arbitrary constants and its Lax pair are presented. In virtue of the Lax pair, a Darboux transformation for the 3-field integrable lattice system is obtained, from which the explicit solutions of the 3-field integrable lattice system are given.

The problem of a two-level atom interacting with single mode cavity field is considered, however, the optical cavity is filled with new structure of a generalized nonlinear Stark shift via Ξ configuration. One starts with a three-level trapped atom interacting with the quantized field of center of mass motion thus a Hamiltonian for one-phonon process with nonlinearities is derived. Through the elimination of the intermediate level by using the adiabatic elimination method, we generate a new structure of effective Hamiltonian for a two-level atom with a nonlinear Stark shift. The temporal evolution of the atomic inversion is studied, we introduce that in the presence of the Stark shift parameter the atom leaves in a maximal entangled sate. We use the von Neuman entropy to measure the degree of entanglement between the atom and the field. After adding the nonlinear Stark shift the system never reaches the pure state. Also we study the Q-function for obtaining more information in phase space for this system. These aspects are sensitive to changes in the Stark shift parameter. The results shows that the effect of the nonlinearity in the Stark shift changes the quasiperiod of the field entropy and hence the entanglement between the particle and the field.

Taking a loop algebra we obtain an integrable soliton hierarchy which is similar to the well-known Kaup–Newell (KN) hierarchy, but it is not. We call it a modified KN (mKN) hierarchy. Then two new enlarged loop algebras of the loop algebra are established, respectively, which are used to establish isospectral problems. Thus, two various types of integrable soliton-equation hierarchies along with multi-component potential functions are obtained. Their Hamiltonian structures are also obtained by the variational identity. The second hierarchy is integrable couplings of the mKN hierarchy. This paper provides a clue for generating loop algebras, specially, gives an approach for producing new integrable systems. If we obtain a new soliton hierarchy, we could deduce its symmetries, conserved laws, Darboux transformations, soliton solutions and so on. Hence, the way presented in the paper is an important aspect to obtain new integrable systems in soliton theory.