Forthcoming articles

Other Index

Forthcoming articles     

Impurity compensation and band-gap renormalization in double-quantum-wires

We investigate the band-gap renormalization due to electron-electron interaction in the n-type doped GaAs-based double-quantum-wire systems. Electron self-energy is calculated using the leading-order perturbation theory (GW) within the full random-phase-approximation (RPA). We include the impurity effects through Mermin expression and show that decreasing the spacing in double-wire system can compensate partly the undesirable effect of impurities on the band-gap renormalization. Therefore, it is possible to offset the effect of impurity in related devices and to adjust the band-gap. We also, apply a constant electric field to one of the wires. It is shown that the change of the band-gap renormalization in the other wire will be insignificant if the drift velocity does not exceed Fermi velocity.     

Measurement and modeling of three-dimensional sound intensity variations due to shallow-water internal waves

Broadband acoustic data (30-160 Hz) from the SWARM'95 experiment are analyzed to investigate acoustic signal variability in the presence of ocean internal waves. Temporal variations in the intensity of the received signals were observed over periods of 10 to 15 min. These fluctuations are synchronous in depth and are dependent upon the water column variability. They can be explained by significant horizontal refraction taking place when the orientation of the acoustic track is nearly parallel to the fronts of the internal waves. Analyses based on the equations of vertical modes and horizontal rays and on a parabolic equation in the horizontal plane are carried out and show interesting frequency-dependent behavior of the intensity. Good agreement is obtained between theoretical calculations and experimental data.     

Metric and Complete Metric σ-Frames

A -frame is a lattice in which countable joins exist and binary meets distribute over countable joins. In this paper, the category MFrm, of metric -frames, is introduced, and it is shown to be equivalent to the category MLFrm _u, of metric Lindelöf frames.Finally, it is shown that the complete metric -frames are exactly the cozero parts of complete metric Lindelöf frames.     

Numerical iterative method for Volterra equations of the convolution type

The objective of this paper is to present an algorithm from which a rapidly convergent solution is obtained for Volterra integral equations of Hammerstein type. Such equations are often encountered when describing the response of viscoelastic materials where the time dependency of the material properties is often expressed in the form of a convolution integral. Frequently, singularity is encountered and often ignored when dealing with the constitutive equations of viscoelastic materials. In this paper, the singularity is incorporated in the solution and the iterative scheme used to solve the equation converges within six iterations to a typical toleration error of 10^?5. The algorithm is applied to the strain response of a polymer under impulsive (constant) loading and the results show excellent correlation between the experimental and analytical solution. Copyright © 2010 John Wiley & Sons, Ltd.     

Equational Compactness of G-sheaves

Purity and equational compactness play a role at least in the Theories of Modules, Acts, Model, and Category. Adámek and Rosický have studied them categorically, Rothmaler model-theoretically, and some authors, including Banaschewski, Gould, and Normak have studied these notions on G-acts. We take both the group G and the set A in the definition of a G-act to be sheaves and study equationally compact G-sheaves. We get different kinds of equationally compact G-sheaves, study them and their interrelations, give some conditions for their proper behavior, and generalize some of the existing results.     

Combined finite difference and spectral methods for the numerical solution of hyperbolic equation with an integral condition

In this work the combined finite difference and spectral methods have been proposed for the numerical solution of the one‐dimensional wave equation with an integral condition. The time variable is approximated using a finite difference scheme. But the spectral method is employed for discretizing the space variable. The main idea behind this approach is that we can get high‐order results. The new method is used for two test problems and the numerical results are obtained to support our theoretical expectations. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007     

XPS study of some selected selenium compounds

X-ray photoelectron spectroscopy (XPS) of the Se 3d peak for Se in Se, SeO₂, As₂Se₃, ZnSe, CdSe, CoSe, FeSe, CrSe, VSe₂ and TiSe were studied. It was found that, firstly, in the case of As₂Se₃, ZnSe, CdSe, CoSe and CrSe, as the change in electronegativity of the anion increases, the change in the binding energy value of the Se 3d peak also increases and, secondly, in all of the Se compounds studied, the Se-Se bond in pure Se is stronger than the Se-x bond, where X = As, Zn, Cd, Co, Fe, Cr, V and Ti.     

Kinetic investigation of aquation of some Fe(II) Schiff base amino acid complexes

Kinetics of aquation of some Fe(II) Schiff base amino acid complexes was followed spectrophotometrically. The Schiff base ligands were derived from salicylaldehyde and isoleucine, leucine, serine, methionine, tryptophan, or histidine. The reaction was studied in aqueous media, aqua–propanol mixtures, and in the presence of different concentrations of KBr. Moreover, the activation parameters were calculated and discussed for structures and other physical properties observed. The reaction was acid catalyzed and the general rate equation was suggested as follows: rate = k_obs [complex], where k_obs = k₂ [H⁺]. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 372–379, 2010