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International Review
of PHYSICS - Papers
The Failure of Maxwell's Equations as a Basis for a Photon Model in the
Vacuum State
by Bo Lehnert
Abstract - The
well-known solutions of Maxwell's equations in the vacuum state are
reconsidered in plane, cylindrical and spherical geometry, and are
compared to the requirements on a physically relevant model for the
individual photon. The solutions result in a vanishing angular momentum
(spin) in respect to the direction of wave propagation, and do not meet
these requirements. There is symmetry between the electric and magnetic
fields of Maxwell's equations in the vacuum. This symmetry is broken in
a revised electromagnetic theory based on a nonzero electric field
divergence in the same state, thereby resulting in a photon model with
spin.
Copyright © 2008 Praise Worthy Prize S.r.l. -
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Keywords:
Maxwell’s equations, Vacuum state, Photon, Spin.
Mathematical
Model for Magnetohydrodynamic Equilibrium Study of Tokamak Plasma
by Sifia Belgherras,
Tayeb Benouaz, Ali Cheknane
Abstract - This
paper presents a study of the interaction of a magnetic field with
plasma in tokamak. Our aim is to determine the equilibrium state; in
other words the states where it can be a good confinement by using the
magnetohydrodynamic (MHD) approach.
Copyright © 2008 Praise Worthy Prize S.r.l. -
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Keywords:
MHD, Tokamak, Magnetic confinement, Free borders.
Abstract
-
The characteristics of laser produced Ti alloy
(Ti-Cu) plasma are used to investigate a time-resolved diagnostic
technique for the emitted spectra from the plasma by using a combination
of Echelle spectrograph with an ICCD camera. The plasma is produced by
focusing a Q-switched Nd:YAG laser at wavelength 1064 nm and pulse
duration of 6 ns with repetition rate of 10 Hz in air at atmospheric
pressure. The plasma is generated with a 670 mJ laser pulse and measured
in one location. The line spectra are analyzed at different delay times
(0.5-10 µs) and fixed gate width of 2 µs. The spectroscopic measurements
are devoted to determine the excitation temperature by using Boltzmann
plot for the spectral lines of Cu I which are free from self-absorption.
This is done by checking the ratio of emission intensities of multiplet
spectral lines. Under the assumption of local thermodynamical
equilibrium (LTE), the electron density is deduced from the Stark
broadening measurements at different delay times. The results obtained
are compared with other results in the literatures.
Copyright © 2008 Praise Worthy Prize S.r.l. -
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Keywords:
Laser ablation, Plasma parameters, Titanium alloy.
Abstract
-
This paper deals with the investigation and the
simulation of the electromagnetic power transmitted in a WR340 waveguide
partially filled with argon plasma over a range of frequencies enabling
the propagation of the fundamental mode TE10 . Unlike
previous approaches where the permittivity of the plasma is either
considered constant, or evaluated at a fixed frequency or where the
collision frequency is neglected, the analysis takes into account the
variations of this parameter in determining the power absorbed by the
plasma and a FEMLAB simulation is undertaken to show the variations of
the electrical field. Results show that at frequencies close to the
plasma frequency the amount of power delivered to the plasma is minimal
due to maximal attenuation.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
Microwave power, Collisional plasma, Complex permittivity, Wave
complex constant, Rectangular waveguide.
Where Are the
Black Holes in Radio Lobes?
by Shirin Haque, Mauri
Valtonen
Abstract - The
pressure observed in radio lobe hot spots in radio galaxies is often
found to be discrepant by an order of a million or more between what is
observed and what is expected. This paper takes an alternate approach to
determine instead how far the hot spot is from the black hole where the
beams originate. It is generally found that the black hole is at the
edge of the hot spot.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
Black hole physics, Galaxies, Quasars.
Multiple
Scattering Theory via Quark Model
by A. S. Shalaby
Abstract - Within
the formalism of Glauber’s multiple scattering theory, the elastic
scattering of proton with light- and medium-weighted nuclei (A≥2) has
been investigated by considering the quark structure of their
constituents. The proton-nucleus calculations for the differential and
total elastic cross-sections are performed using both a full series
expansion of the optical phase-shift function and an optical phase-shift
function calculated through fourth order. We also calculated the same
differential and total elastic cross-sections using a conventional
nucleon model together with Glauber theory. These calculations are
carried out for the elastic collisions, p-deuteron at incident momenta
of PL=148, 174, 221, 248, 270, 289, 346 and 384 GeV/c, p - 6C12, p -
8O16 and p - 20Ca40 at center-of-mass energies of √S= 23.5, 30.7, 44.7
and 52.8 GeV and the results are compared with the available
experimental data. The comparison reflects that the terms up to fourth
order are adequate in describing such types of collisions and also shows
that the nucleon model reproduces more satisfactorily the available
experimental data than the quark model evaluations.
Copyright © 2008 Praise Worthy Prize S.r.l. -
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Keywords:
Glauber’s multiple scattering theory, Quark model, Nucleon
model, Differential cross-section, Total elastic cross-section.
Collective
Clusterization in Hot and Rotating Nuclei: Preformed-cluster based
Dynamical Cluster-decay Model
by Raj K. Gupta,
Sham K. Arun, Raj Kumar, and Niyti
Abstract -
A dynamical collective clusterization model, called the dynamical
cluster-decay model, is developed for the decay of a hot and rotating
compound nucleus formed in the low-energy heavy ion reactions. The model
is a non-statistical description for the decay of a CN to light
particles, intermediate mass fragments, fusion-fission and quasi-fission
(equivalently, capture) processes, and hence is given as an alternative
to the well known Hauser-Feshbach analysis (statistical evaporation
code) and statistical fission models. The quasi-fission or capture is
the non-CN contribution, determined empirically. The deformations and
orientation degrees of freedom (for compact orientations) of the
incoming nuclei and of out-going nuclei/ fragments are also included.
The model considers all decay products as dynamical mass motions of
preformed fragments or clusters through the interaction barrier, thereby
including structure effects of the CN explicitly. The only parameter of
the model is the neck-length parameter, which is related to the total
kinetic energy TKE(T) or effective Q-value Qeff(T) at temperature T of
the hot CN. This parameter could also be defined in terms of the CN
binding energy and ground-state binding energies of the emitted
fragments. The model is so far applied to the decay of compound systems
48Cr*, 56Ni*, 116,118,122Ba*, 164Yb*, 246Bk*, and 292114*, formed in
various reactions at different incident center-of-mass energies. Both
the cross sections and TKE or TKE are considered. For
ground-state (spontaneous) decays, the model gives the phenomenon of
exotic cluster radioactivity.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
Collective Clusterization Model, Compound Nucleus decay,
Quasi-Fission.
Numerical
Study of Natural Convection in a Square Porous Cavity Heated by Bottom
Wall
by W. Alimi, R. Chouikh,
A. Guizani
Abstract -
This paper deals with natural convection in a
square porous media heated by bottom wall, driven by cooperating thermal
and buoyancy forces. The physical model for the momentum conservation
equation makes use of the Extended Darcy model, and the set of coupled
equations is solved using a finite volume approach. The numerical
simulations presented here span a wide range of the main parameters (the
Rayleigh and Darcy numbers). The results are compared with previous
numerical data. The results are mainly analyzed in terms of stream
functions, temperature profiles, local and average Nusselt numbers at
the bottom wall of the enclosure for uniform and sinusoidal heating. The
different heat transfer regimes meaning conduction and convection are
investigated for various ranges of the governing parameters.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
Natural convection; Square cavity; Porous medium; Extended Darcy
model.
Mixed
Convection of Micropolar Fluids Flow with Ohmic and Radiation Effects Past a
Stretching Sheet
by Kai-Long Hsiao
Abstract -
A mixed convection problem for micropolar fluid flow with ohmic and
radiation effects micropolar fluids past through a stretching sheet has
been studied. Governing equations have been analyzed by a combination of
the similarity transformation and a second-order accurate
finite-difference method. The dimensionless parameters Pr, M, G1, G, Ec,
F, E1 and Gx are represented the flow field important factors and used
to analyze the characteristic of the flow. The numerical results
indicate that, an increase in one of the parameters Pr, F, E1 and Gx
gives an increase in heat transfer effects, but for one of the
parameters G1, G and M will reduce the flow field’s momentum, angular
momentum and heat transfer effects.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
Mixed convection, Magnetic field, Radiation effect, Micropolar
fluid, Stretching sheet.
Direct
Numerical Simulation of Turbulence Characteristics Generated by Fractal Grids
by Kouji Nagata, Hiroki
Suzuki, Yasuhiko Sakai, Toshiyuki Hayase, Takashi Kubo
Abstract -
Turbulence characteristics in the spatially developing fractal-generated
turbulence are investigated by means of the direct numerical simulation
(DNS). Following the experiments by Hurst & Vassilicos (Physics of
Fluids 19, 035103, 2007), three kinds of fractal grids, namely, cross, I
and square types, are numerically constructed using the immersed
boundary method. The results show that fractal grids generate high
turbulence intensities compared with the classical grid turbulence using
a biplane square mesh grid at the same mesh Reynolds number. Among the
three types, the fractal square grid is the best to generate quasi
homogeneous and isotropic turbulence in the far downstream decaying
region. The integral length scale in the fractal-generated turbulence
with a fractal square grid remains approximately constant in the
decaying region, whereas it grows downstream in the classical grid
turbulence. These results are in good agreement with the previous
experiments although the Reynolds number is small in the present DNS.
The enstrophy is much larger in the decaying region of fractal-generated
turbulence than that in the classical grid turbulence. In the
fractal-generated turbulence, vortex structures are finer than those in
the classical grid turbulence and they form clusters.
Copyright © 2008 Praise Worthy Prize S.r.l. -
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Keywords:
DNS, Finite Difference Method, Fractal, Grid Turbulence, Isotropic
homogeneous Turbulence.
On
Using Multiscale Product to Extract Crackles from Wheezing Sound Signal
by Fatma Ayari, Ali T.
Alouani, Mekki Ksouri
Abstract -
Auscultation-based analysis of pulmonary
disorders relies heavily on the presence of adventitious sounds and on
the altered transmission characteristics of the chest wall. The phase
information of the respiratory cycle within which adventitious sounds
occur include a wealthy tank source of vital physiological and
pathological information that is of critical importance for clinical
diagnosis and is very helpful in diagnosing different diseases. The
novelty of our study is to extract crackles from both wheezing sound
signals and vesicular breath sounds, for this a combined method based on
wavelet multiscale product and Hilbert transform seams to be proficient
tool to dig up crackles.. This paper introduces a method that can
enhance accuracy of diagnosis of lung physiological vital signs. Lung
sound signals, from the Steven Lehrer database, shows the power of the
proposed combinatory approach in detecting the presence of crackles. The
analysis results justified the efficient performance of this combinatory
approach to reveal and illustrate crackles.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
Lund sound, vesicular breath sound, lung disease, wavelet, Hilbert
transform, diagnosis.
Photobleaching-electron
Density for the Molecular Structures of Pyropheophorbide a and Pyropheophorbide
Methyl Ester in Dimethylformamide Solution
by S. Al-Omari, A. Ali,
A. M. Alsmadi, M. Al-Sugheir
Abstract -
Comparative spectroscopic study and quantum calculations were performed
on the photobleaching of pyropheophorbide methyl ester (PPME) and
pyropheophorbide a (PPa) in dimethylformamide (DMF) organic solvent. The
photobleaching efficiency of PPa was found to be higher than that of
PPME. Quantum calculations on the molecular structures of the
investigated compounds revealed that the outer carbon atoms were
susceptible to the attack by singlet oxygen molecule (1O2).
Copyright © 2008 Praise Worthy Prize S.r.l. -
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Keywords:
Electron density, Singlet oxygen, Tumor, Hamiltonian operator,
Photobleaching.
Determination
of the Experimental Parameters for a Maximum Hardness of AlN Thin Films by the
Response Surface Methodology
by M. Zadam, J. A.
Adamczyk, A. Tricoteaux, N. Horny, P. Y. Jouan, M. A. Djouadi, M. Y. Debili
Abstract -
In this study, AlN thin films were deposited on
silicon substrates by DC reactive magnetron sputtering. The crystal
structure of the films was analyzed by X-ray diffraction, The residual
stresses in our AlN films were calculated by the bend-bending method,
where the radius of the bend, coated substrate Si (100) is measured
before and after deposition and hardness by using the Vickers
microindentation technique. In a primary study, an approximate operating
point, allowing limited areas of changes in working pressure, discharge
current and the percentage of nitrogen has been determined. A three
factors Doehlert matrix, has been used for the setup of the experimental
design, which allows the use of the statistical response surface
methodology (RSM) in a spherical domain. A four dimensional surface
response, which represents the hardness as a function of sputtering
pressure, discharge current and nitrogen percentage was obtained. In
order to optimize the hardness, we showed that the most important
parameter is the pressure.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
AlN thin films, Response Surface Methodology, DC magnetron
sputtering.
Hydro-Chemical
Characterization of Water Ain Sahel Kharrouba Sources of the Northwest Region of
Morocco
by Abdelhak Ghouli,
Kamal Gueraoui, Myrieme Walid, Abdallah El Abidi, Elarbi Idrissi, Mohammed
Taibi, Abdellah El Hammoumi, Mohammed Kerroum
Abstract -
In this work, attention has been paid to the
physico-chemical analysis of water sources in the north-west of Morocco
in particular AÏN SAHEL KHAROUBA, located 40 km south of Tetouan city
and 22 km north of Chéfchaouen city. With the help of the method of
Piper diagram, the waters of different origins are easily differentiated.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
Spring water, Physico-chemical analysis, Ccorrelation matrix,
Piper Chart, Schoeller-Berkaloff Diagram.
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