International Journal of Modern Physics B

Nanocrystalline zirconium nitride/oxide "zirconium oxynitride" nanocomposite film is deposited on zirconium substrate by dense plasma focus device at room temperature. X-ray diffraction of irradiated samples reveals that different phases (ZrN, Zr₃ N₄ and ZrO₂) of zirconium nitride and zirconium oxide are evolved. The crystallinity of these phases depends on axial positions as well as ion energy flux. Scanning electron microscopy shows that the deposited film is more compact at lower axial position, which is due to higher ion energy flux. Energy dispersive X-rays spectroscopy shows that the presence of nitrogen concentration decreases by increasing the axial position. Maximum microhardness value for the deposited layer is found to be 7200 ± 12 MPa at 10 gram imposed load.

Nanostructured carbon nitride films have peen synthesized by using a low-cost Penning discharge (PD) plasma-sputtering source. The influences of different working gas pressures on the surface morphologies, chemical compositions, bond structures, and mechanical properties of deposited carbon nitride thin films have been investigated using Scanning probe microscope (SPM), X-ray photoelectron spectroscopy (XPS) measurements, Raman spectroscopes, and nanoindentation measurements, respectively.

SPM and XPS data indicate the variations of the root-mean-square roughness (R_RMS) of the samples surfaces from 7.5 nm, 11.4 nm, to 17.7 nm, and an increase of sp² fraction inside the films from 22.8% to 26.9% with an up-shift of the deposition gas pressures. In contrast, the sp³ content decreases from 17.5% to 11.8%. The shifts of D and G peaks and variations of band intensity (I_D/I_G) have been observed in Raman spectra. The hardness of samples is reduced with increasing N₂ partial pressure applied during film deposition.

In this paper, we study the structure of vortex lattices in a trapped superfluid Fermi gas in the unitary region near the superfluid transition temperature. A phenomenological approach based on the Ginzburg-Landau theory is used. Two types of stable triangular vortex lattices are found numerically at the same rotation frequency. In type (A), the trap center is occupied by a vortex; in type (B), there are three vortices closest to the trap center which is unoccupied. The lattice structures at different rotation frequencies and temperatures are analyzed. The vortex density increases linearly with the rotation frequency, very close to the analytical estimation. The superfluid and type-(B) vortex lattice do not disappear together. At high rotation frequencies, the vortex lattice disappears, but there exists a localized superfluid state near the trap center. The superfluid vanishes at a critical rotation frequency consistent with the theory for the upper critical magnetic field of type-II superconductors.

Determination of lattice misfit and microstructural parameters of the coherent precipitates in Ni based alloy Inconel-625 is a challenging problem as the diffraction peaks of the precipitate and the matrix are completely overlapping. X-ray Diffraction Line Profile Analysis (XRDLPA) has been used to characterize the bulk samples of Inconel 625 at different heat-treated conditions to determine the lattice parameters of the parent phase and also the coherent precipitates by the separation of the overlapping peaks. The lattice misfits of the coherent precipitates with the matrix and their microstructural parameters like size and strain have also been determined.

Assuming the Rössler system as a reference, this paper studies two cases of chaotic synchronization of a pair of (master and slave) systems: one with fully uncertain parameters for both, the other where the master system has fixed given parameters while the slave system is endowed with uncertain parameters. The respective adaptive controller based on parameter identification is then designed, according to the Lyapunov stability theorem. Then, it is proved that the two controllers are capable of making the two (identical) Rössler systems asymptotically synchronized. Numerical simulation results further testify the efficiency of controllers.

This investigation deals with the influence of an inserted endoscope and a magnetohydrodynamic (MHD) third grade fluid on the peristaltic flow under zero Reynolds number and long wavelength approximations. A uniform magnetic field is applied transversely to the flow. The mathematical model considers an incompressible fluid through the gap between concentric uniform tubes, such that the inner tube is rigid and the outer tube travels down its wall. The governing non-linear equation has been modeled and then solved for arbitrary values of Deborah number. The effect of the Hartmann number, Deborah number, volume flow rate, radius ratio and the various parameters entering into the problem are discussed on the velocity components, axial pressure gradient, pressure rise and frictional forces on the inner and outer tubes.

In this presentation, we considered the atomic decay (but not for the cavity) for a two-level atom interacting with a single mode of electromagnetic field. The exact solution of the master equation in the case of a high-Q cavity with atomic decay is found. The effects of the atomic damping for a thermal reservoir on the temporal evolution of partial entropies of the atom or the field, and the total entropy as a quantitative entanglement, was measured. The degree of entanglement, through the sum of the negative eigenvalues of the partially transposed density matrix and the negative mutual information, has been studied and compared with other measures.

Starting from a new four-by-four matrix eigenvalue problem, a hierarchy of Lax integrable evolution equations with four potentials is derived. The Hamiltonian structures of the resulting hierarchy are established by means of the generalized trace identity. The Liouville integrability for the hierarchy of the resulting Hamiltonian equations is proved.

Comparison of homotopy perturbation method (HPM) and variational iteration method (VIM) is made, revealing that the two methods can be used as alternative and equivalent methods for obtaining analytic and approximate solutions for different types of differential equations of fractional order. Furthermore, the former is more general and powerful than the latter. Numerical results show that the two approaches are easy to implement and accurate when applied to differential equations of fractional order.

A complex hexagonal lattice photonic crystal with a two-dimensional (2D) periodic dielectric background is proposed. The photonic band modulation effects due to the 2D periodic dielectric background are investigated. We find that the position and width of the complete photonic band gap (PBG) sensitively depend on the dielectric constants of the 2D periodic dielectric background. The radii of the two alternating air holes have significant influence on the relative width of the complete PBG.

This paper addresses the adaptive synchronization problem of a class of different uncertain chaotic systems. A general adaptive robust controller and parameters update rule are designed. It is proved theoretically that the controller and update rule can make the drive-response systems with different structures asymptotically synchronized, and change the unknown parameters to constants when noise exists. When the drive system is certain, the unknown parameters of the response system can be updated to the predicted values. The results of numerical simulations show the effectiveness of the adaptive controller.