Latest issue

Home>Products>Journal and Reviews>I.RE.PHY.>Latest issue

International Review of PHYSICS - April 2007 - Papers

Molecular dynamics simulation for uranium hexafluoride, by S .M. El-Sheikh
Quantum Accelerator Modes in the Absence of Gravity, by Oded Barash, Itzhack Dana
A Revised Electromagnetic Theory
Dust-plasma sheath: the sheath thickness and the energy of the grain, by M. Eddahby, M. Samir, A. Dezairi, D. Saifaoui and M. El Mouden
Tin ions irradiation effects on Gold, by Farrakh Shahzad and Muhammad Shahbaz Anwar
Quantum Limitations of Electron Transport in Ultra-Narrow Nanowires, by K. Arutyunov, M. Zgirski, K.-P. Riikonen, and P. Jalkanen
Activities of some radionuclides in some water, suspended matter and sediment samples from the Moulouya River area at the North-east of Morocco , by E. Al Ibrahmi, A. Choukri, O.-K. Hakam, S. Chakiri, J-L Reyss
Identification of Electromagnetic Parameters Through GRBF Neural Network and Finite Element Modeling by T. Hacib, M. R. Mekideche, and N. Ferkha
A Neural Approach to Estimate the Radiation Damage of the Solar Panels, by F. Djeffal, M. Chahdi
The Great Season Climatic Oscillation, by A. Boucenna
The modified Klein – Gordon equation for Neolithic population migration, by Magdalena A. Pelc

International Review of PHYSICS - Papers

Molecular dynamics simulation for uranium hexafluoride
by S .M. El-Sheikh

Abstract - The pressure induced phase transformation of solid UF₆ was studied by applying the constant temperature constant pressure (T, P, N) molecular dynamics simulation technique on small clusters (108 and 256 molecules) to investigate its properties in its condensed phases, using an intermolecular potential model includes dispersion, coulomb, and induction terms. A numerical value of the melting temperature at high pressure as well as pressures at phase transitions was estimated. Our data show that phase I is monoclinic (partially disordered), phase II is monoclinic (ordered) and both has the same P₁ symmetry.

Keywords: Molecular dynamics simulations, UF₆, phase transitions, high pressure.

Quantum Accelerator Modes in the Absence of Gravity
by Oded Barash, Itzhack Dana

Abstract - The experimental study of cold atoms kicked by a pulsed optical standing wave and falling under gravity has led to the important discovery of the “quantum accelerator modes” (QAMs). It is shown that QAMs in the absence of gravity can feature a rotational quasiregularity which cannot be found in the usual QAMs. Thus, QAMs with non-accelerating quasiregular segments may be used to control the quantum motion of atoms in a way which is not possible in the presence of gravity.

Keywords: Control, Experimental Quantum Chaos, Quantum Accelerator Modes, Quantum Resonances, Quasiclassics, Rotating Accelerator-Mode Islands.

A Revised Electromagnetic Theory
by B. Lehnert

Abstract - A revised Lorentz and gauge invariant electromagnetic theory has been developed, as based on a nonzero electric field divergence and an associated space-charge current density in the vacuum state. The theory aims beyond Maxwell’s equations and presents new solutions of a number of fundamental problems. So far the latter have not been satisfactory explained in terms of conventional electromagnetic theory and quantum electrodynamics (QED). Important applications of the revised theory are presented, such as on a model of the electron and its point-charge-like nature, the self-energy problem, the radial force balance, and a quantized minimum value of the electron charge. There are further applications on the individual photon and its angular momentum, its spatially limited geometry, the associated needle radiation, and the particle-wave nature of the photoelectric effect and two-slit experiments at low photon densities.

Keywords: Electromagnetic field theory, vacuum state, quantum electrodynamics, leptons, photon.

Dust-plasma sheath: the sheath thickness and the energy of the grain
by M. Eddahby, M. Samir, A. Dezairi, D. Saifaoui and M. El Mouden

Abstract - A dust grain in plasma acquires an electric charge by collecting ions and electrons from the plasma. The presence of charged dust grains can significantly affect the behavior of plasma in which they are immersed because of their unusual value of charge-to-mass ratio. Both electrons and ions will be collected by the dust grains, but since the electrons move about more swiftly than the ions; the grains tend to acquire a negative charge. Under the simplest approximation, all the dust grains may be considered to have the same mass and equilibrium charge, and so they are equivalent to a second ion species. In this work an attempt is made to give the impact energy of dust particle at the wall (electrode) and the sheath thickness. The theory and numerical results are presented for collisional dusty plasma.

Keywords: collisional parameter, dusty plasmas, impact energy, sheath, sheath width.

Tin ions irradiation effects on Gold

by Farrakh Shahzad and Muhammad Shahbaz Anwar

Abstract - The aim of this work is to study the changes produced in gold after laser produced ion irradiation. A pulsed Nd: YAG laser (Pulse duration 9-12 ns, power 1.1MW) is used to produce Tin ions which were irradiated on gold. XRD pattern of gold are taken before and after ion irradiation. A comparison of these patterns reveals that the intensity of diffraction lines in XRD pattern changed after laser produced ion irradiation owing to displacement (knocked in and knocked out) of gold atoms. SEM micrographs of tin ions irradiated Gold sample not only provide evidences of sputtering and crater formation but also indicate re-deposition of sputtered material. Thermal spikes are also observed in SEM micrograph.

Keywords: Laser produced ions, ions gold interaction, sputtering.

Quantum Limitations of Electron Transport in Ultra-Narrow Nanowires
by K. Arutyunov, M. Zgirski, K.-P. Riikonen, and P. Jalkanen

Abstract - An ion beam based dry etching method has been developed for progressive reduction of dimensions of pre-fabricated nanostructures. The method has been successfully applied to aluminum and bismuth nanowires. We were able to reduce the effective diameter of nanowires from ~ 100 nm down to ~ 8 nm without noticeable degradation of the sample structure. In case of a normal metal (bismuth) we observed a periodic variation of the wire resistance with reduction of its effective diameter. The effect is associated with quantum size phenomenon: crossing of the size-quantized energy levels with the Fermi level. In superconducting nanowires (aluminum) with effective diameter < 15 nm we have observed a pronounced widening of the R(T) transition, which cannot be explained by conventional fluctuation models. For these ultra-narrow superconducting nanowires the zero state resistance is not reached even at T0. The effect is associated with quantum phase slip phenomena. Both effects have a universal validity and their assessment is crucial for further developments of nanoelectronics.

Keywords: electron transport, nanowires, size effects, semimetals, non-equilibrium superconductivity.

Activities of some radionuclides in some water, suspended matter and sediment samples from the Moulouya River area at the North-east of Morocco
by E. Al Ibrahmi, A. Choukri, O.-K. Hakam, S. Chakiri, J-L Reyss

Abstract - Analysis results (²³⁸U, ²³⁴U, ²²⁶Ra, 228Ra activities; ²³⁴U/²³⁸U, ²²⁸Ra/²²⁶Ra and ²²⁶Ra/²³⁸U activity ratios) are reported for 4 sediment and 5 suspended mater samples collected from the Low Moulouya region at the North-east of Morocco and for 18 natural water samples collected from the High Moulouya region (Moulouya river, effluents, wells, springs, lakes, barrages and tap water). For sediment and suspended matter, activities of U and Ra isotopes were measured by gamma spectrometry. For water samples, activities and activity ratios of uranium isotopes were measured by alpha spectrometry whereas those of radium were measured by gamma spectrometry. Uranium and radium activities are higher in sediment and suspended matter than in water samples. They are also higher in suspended matter than in sediments because sediments contain the concentrated leached detrital soils and sable. The measured activities of uranium and radium isotopes in all analysed water samples are comparable to those already published in our previous works except for two samples collected from lakes situated at Zeida area. These lakes are the former sites of mine extraction where the accumulated water is in permanent contact with mines. These mines could contain uranium witch responsible of the relatively elevated activities of 234U and 238U found for the first time in lakes water in Morocco.

Keywords: Moulouya river, Natural Radioactivity, Natural water, Sediment, Suspended mater.

Identification of Electromagnetic Parameters Through GRBF Neural Network and Finite Element Modeling
by T. Hacib, M. R. Mekideche, and N. Ferkha

Abstract - This paper describes a new methodology for using artificial neural networks (ANN) and finite element analysis in an electromagnetic inverse problem of parameters identification. The approach is used to identify unknown parameters of ferromagnetic materials. The methodology used in this study consists in the simulation of a large number of parameters in a material under test, using the finite element method (FEM). Both variations in relative magnetic permeability and electrical conductivity of the material under test are considered. Then, the obtained results are used to generate a set of vectors for the training of generalized radial basis function (GRBF) neural network. Finally, the obtained neural network is used to evaluate a group of new materials, simulated by the FEM, but not belonging to the original dataset. Performance of the GRBF network was also compared with the most commonly used multilayer perceptron (MLP) network model. The obtained results demonstrate the efficiency of the proposed approach, and encourage future works on this subject.

Keywords: FEM, Parameters identifications, Inverse problem, GRBF neural network.

A Neural Approach to Estimate the Radiation Damage of the Solar Panels
by F. Djeffal, M. Chahdi

Abstract - Solar cells in space are damaged by exposure to energetic protons and electrons. These particles pass through protective coverings and disrupt delicate crystal lattices. The output power of the system is continuously degraded over the mission life. Space power engineers need damage coefficients to predict solar cell power degradation. So, the modelling of solar cells constitutes a research field that is currently very important throughout the world. To continue this evolution, the existing models must be improved and new models have to be developed. In this paper, we present the applicability of the artificial neural network (ANN) for the study of the radiation damage of the solar cells and the development of a neural model allows the evaluation of the degradation of the solar cells parameters (series and parallel resistance, diode coefficient, reverse current density, etc.) under a given irradiation and space fluence. Our results are compared with the experimental ones, analysed and discussed in order to obtain some useful information about the use of the solar cells in space environment.

Keywords: Solar cell parameters; artificial neural network; radiation damage; degradation.

The Great Season Climatic Oscillation
by A. Boucenna

Abstract - The variations of water density and thermal conductivity of the oceans cold region waters according to their salinity lead to suggest a hypothesis of an oscillating climate between two extreme positions: a maximum of hot temperatures and a minimum of cold ones. It will be shown that the distance separating the surface hot streams from the depth cold ones oscillate between two limit values linked to the optimal melting and regeneration glaciers. The melting and regeneration glaciers cycle leads to the Great Saison Climatic Oscillations phenomenon necessary to the regeneration of fresh water resources of our planet.

Keywords: Depth Cold Stream, Great Saison Climatic oscillation, Surface Hot Stream, Water density.

The modified Klein – Gordon equation for Neolithic population migration
by Magdalena A. Pelc

Abstract - In this paper the model for the neolithic migration in Europe is developed. The new migration equation, the modified Klein – Gordon equation is formulated and solved. It is shown that the migration process can be described as the hyperbolic diffusion with constant speed. Comparison to the existing models based on the generalization of the Fisher approach the present model describes the migration as the transport process with memory and offers the possibility to recover the initial state of migration which is the wave motion with finite velocity.

Keywords: hyperbolic diffusion, Klein – Gordon equation, memory transition, Neolithic migration.

International Review of PHYSICS - April 2007 - Papers

Dust-plasma sheath: the sheath thickness and the energy of the grain
by M. Eddahby, M. Samir, A. Dezairi, D. Saifaoui and M. El Mouden

Please send any questions about this web site to info@praiseworthyprize.com

- Copyright © 2005-2012 Praise Worthy Prize -

International Review of PHYSICS - April 2007 - Papers

Dust-plasma sheath: the sheath thickness and the energy of the grain by M. Eddahby, M. Samir, A. Dezairi, D. Saifaoui and M. El Mouden

Please send any questions about this web site to info@praiseworthyprize.com

Dust-plasma sheath: the sheath thickness and the energy of the grain
by M. Eddahby, M. Samir, A. Dezairi, D. Saifaoui and M. El Mouden