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International Review
of PHYSICS - Papers
Through Solutions to the Moments of the Boltzmann Equation for DC Glow
Discharge
by A. Bouchikhi, A.
Hamid
Abstract - At the
stationary state, we present the physical properties of a 1D DC glow
discharge in argon. A hydrodynamic fluid model used in this paper based
on the moments of the Boltzmann transport equation. The resultant set of
governing equations consists of continuity equations (fluxes and
densities) for electrons and ions, an energy equation for electrons and
Poisson's equation. A numerical algorithm based on the flux exponential
finite difference method for continuity's equations and centered finite
difference method for Poisson's equation was developed. The simulation
results are presented in this paper for the densities of charged
particles, the electric voltage, the electric field, the electron’s
temperature and the current’s density. Our results have been compared
with those works of Lin and al [1]. A parametric study varying the
cathode voltage, gas pressure, and secondary electron emission
coefficient predicts many of the well-known features of dc discharges.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
glow discharge, Boltzmann equation, electron Temperature, variable
electron Diffusivity, Poisson's equation.
Simulation
of Ion Transport in the Discharges by the Hybrid Fluid-Monte Carlo
by A. Boumhali, K.
Dzairy, A. Dezairi, M. Samir, M. Eddahby, D. Saifaoui
Abstract - In this
paper we focus on the modelling and simulation of plasma processes
particularly simulation of collision in the discharge zone of space
using the known model hybrid fluid -Monte Carlo. An attempt is made to
simulate the movement of the Argon particles in the discharge zone of
space and to give the impact energy of ions particle. The simulational
study and numerical results are presented for collisional plasma.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
Monte Carlo, Discharge, Hybrid-fluid, Cold Plasma.
Abstract
-
We study the superstring theory with an Abelian worldsheet gauge field.
The components of the gauge field appear as a space and a time
coordinates. We call them as “fictitious coordinates”. The worldsheet
supersymmetry and the Poincare symmetry of this model will be analyzed.
The T-duality and quantization of the two fictitious coordinates also
will be obtained.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
Superstring; Gauge field; Symmetry.
Abstract
-
In this paper we consider the scalar particle creation from the quantum
scalar vacuum by suddenly expanding the spherical shell with Dirichlet
boundary condition. Here, we present a different theoretical scheme
where mechanical oscillations are avoided. It is seen that the total
number of photons is almost 8x106 for smallest b value, 10 nm
and this value remains almost constant over a large values of b, up to
100 micro.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
particle creation, dynamical Casimir effect, creation of
photon.
Complexity in Atoms: an Approach with a New Analytical Density
by J. Sañudo, R.
López-Ruiz
Abstract - In this
work, the calculation of complexity on atomic systems is considered. In
order to unveil the increasing of this statistical magnitude with the
atomic number due to the relativistic effects, a new analytical density
to describe neutral atoms is proposed. This density is inspired in the
Tietz potential model. From the normalization condition and from a
variational calculation of the energy, which is a functional of the
density, the parameters of this density are expanded in powers of the
atomic number. The main ingredients of the energy functional are the
non-relativistic kinetic energy, the nuclear-electron attraction energy
and the classical term of the electron repulsion. The relativistic
correction to the kinetic energy and the Weizsacker inhomogeneity term
are also taken into account. The Dirac and the correlation terms are
shown to be less important than the other terms and they have been
discarded in this study. When the statistical measure of complexity is
calculated in position space with the analytical density derived from
this model, the increasing trend of this magnitude as the atomic number
increases is found.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
Complexity, Density functional, Relativistic effects.
Structural,
Electronic and High Pressure Properties of Barium Chalcogenides
by S. Drablia, H.
Meradji, S. Ghemid, S. Labidi, N. Boukhriss, B. Bouhafs
Abstract - The
structural and electronic properties and the pressure dependence of
energy gaps of barium chalcogenides BaO, BaS, BaSe, BaTe and BaPo in the
rocksalt structure are calculated using a hybrid Full-potential (linear)
augmented plane-wave plus local orbitals (L/APW+l0) within
density-functional theory (DFT). Results are obtained using both the
local density approximation (LDA) and the generalized gradient
approximation (GGA) for the exchange-correlation potentials. The
ground-state properties, like lattice constant, bulk modulus and its
first derivative obtained from our calculations agree very well with
experimental and other theoretical calculations. Band structures and
total density of states are analyzed in great detail. The calculated
energy gap for the series of barium chalcogenides BaS, BaSe, BaTe and
BaPo is found to be indirect (Г- X) except BaO (direct gap X-X), and it
is underestimated by about 40% for both LDA and GGA compared to
experiment. We have also reported the pressure dependence of energy
bands as like values of the pressure coefficients dEg/dV and
volume deformation potentials dEg/d lnV, and other
coefficients.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
Density functional theory; barium chalcogenides, band
structure, density of states, pressure dependence.
Hadron
Structure and Standard Model Parameters
by S. I.
Sukhoruchkin
Abstract -
Empirical relations in parameters of the Standard Model are considered
together with relations in values of stable nuclear energy intervals,
estimates of constituent quark mass, a half of nucleon Δ--excitation and
electromagnetic mass splitting of nucleon, pion and leptons. A common
tuning effect in nuclear data and particle masses is discussed. Combined
study of few-nucleon effects in nuclear binding energies and excitations
resulted in determination of common parameters for different shells
corresponding to residual nucleon interaction and differences in binding
energies of nuclei differing by cluster configuration. Stable intervals
in energies of nuclear states ranging from hundreds of MeV to tens of
keV are determined as parameters of tuning effects in which the QED
radiative correction takes part.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
Hadron structure, particle masses, nuclear data
.
Renormalisation
of Chromoelectric Fields in a Two-Component Preon System
by V. N. Yershov
Abstract -
The dynamics of particles with chromoelectric
fields in a two-body system is discussed within the framework of a preon-based
composite model of the fundamental fermions. The particles in such a
system carry opposite colour charges, so that the diverging chromatic
components of their fields almost cancel. It is found that this
renormalisation leads to establishing an upper bound on the particle
speed. This maximum speed for preons leads to the possibility of
studying the relativistic properties of more complex preon clusters and
of comparing them with the corresponding properties of the fundamental
fermions.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
Composite particles, Preons, Colour fields.
Experimental
Study of Chemo-Mechanical Response of Amorphous Poly(Lactic Acid) Films Exposed
to UV Irradiation
by S. Belbachir, F.
Zaïri, G. Ayoub, U. Maschke, M. Naït-Abdelaziz, J. M. Gloaguen, M. Benguediab,
J. M. Lefebvre
Abstract -
In this work, the impact of ultra-violet (UV) irradiation on the
mechanical behaviour of amorphous biodegradable poly(lactic acid) (PLA)
films is analysed. PLA films were submitted to UV irradiation for
increasing exposure time. Two kinds of experiments were conducted,
chemical and mechanical. The chemical degradation was measured by gel
permeation chromatography technique. The PLA films were mechanically
investigated by stretching experiments before and after UV exposure.
Their mechanical properties were obtained by a video-controlled system.
Our purpose is to establish the relationship between macroscopic
mechanical response and molecular parameters such as the molecular
weight, and external solicitations such as temperature, strain rate and
UV irradiation. The interactions between photodegradation and changes in
polymer properties are discussed.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
Poly(lactic acid); UV irradiation; Molecular weight; Mechanical
properties.
Characterization
of the PV Module PWX500 in Site of Bechar (Algeria)
by M. Sellam, M.
Bourahla
Abstract -
Our country is supported by a very important
solar site, it is almost sunny 10 months over the year with an average
incidence of 966 w/m2 for one intermediate duration of 10 hours /days
This encourages us to be directed towards an energy source available,
free and ecological while taking into account the scientific solutions
justified to make the cost competitive, this while exploiting the
configuration of the assembly or with the hybridization of the system.
The characterization is the means par excellence which makes it possible
to study the behavior of a photovoltaic module .The goal of the
characterization is the determination of the principal parameters
describing the electrical performances of the module. The object of this
study is to have some results obtained during the characterization of
the photovoltaic modules constituting the field installed at laboratory
in University Center of Bechar. The experimental characteristics
obtained were analyzed in order to determine the performances of the
modules and their representative parameters (energetic efficiency,
maximum power, fill factor…). These characteristics were relocated in
the standard conditions in order to compare them with the
characteristics data provided by the manufacturer.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
Characterization, Configuration, Photovoltaic, Maximum Power, Cost
of energy.
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