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International Review
of PHYSICS - Papers
Study of Reticulation RTM6 System by DSC and FTIR Spectroscopy
by L. Merad, M. Cochez, F. Jochem, M. Ferriol, P. Bourson, B. Benyoucef
Abstract - Polymerization reactions are based on complex processes that are somewhat difficult to predict via mathematical models, especially without experimental data. The goal of this paper is to present a comparison between DSC and infrared spectroscopy. Differential Scanning Calorimetry (DSC) is the industry-standard method for determine the cure of a polymer, but it is a labor-intensive method that is also fairly slow. Infrared spectroscopy is used to monitor the cure chemistry of DGEBA (Diglycidyl Ether of Bisphenol A) and to observe in-situ the evolution of the reticulation.
Copyright © 2008 Praise Worthy Prize S.r.l. -
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Keywords:
Epoxy systems, process monitoring, DSC, FTIR spectroscopy.
Optical Properties of Two Interfaces of Thin Film, Used to Study the Metallic Diffusion
by Kh. Ayadi
Abstract - An experimental procedure has been devised to study the diffusion of impurities throughout thin films using the surface plasmon resonance technique. When such a film is in contact with two dielectrics having different indices the surface plasmons, at two interfaces of a metallic film can be optically excited simultaneously, by attenuated total reflection (ATR). The plasmons are totally decoupled.. Experimental results of the diffusion of gold through thin silver films are presented using the experimental procedure outlined above.
Copyright © 2008 Praise Worthy Prize S.r.l. -
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Keywords:
Surface plasmon, attenuated total reflexion, diffusion.
Abstract -
In this paper we present results, using a single integral equation approach with Nyström discretization method, to the numerical solution for the electromagnetic scattering from infinitely long cylindrical cavities. The configurations treated vary from one closed homogeneous cavity to the case of open cavities with multiple inclusions. The method permits accurate and reliable solutions in cavities of arbitrary shape boundary. According to the method, the solutions in the cavities are expressed in terms of layer potentials. Numerical implementations of the method are described and validated by comparison with other methods in the literature. We present results for resonance and field calculations.
Copyright © 2008 Praise Worthy Prize S.r.l. -
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Keywords:
Integral equation, Nyström method, eigenvalues.
Abstract -
The quantification of radiative transfer is important in industrial applications such as the design of combustion chambers, furnaces and high temperature exchangers. Indeed, we will be more economic, if we know the time disposed for a heating or cooling process and the accurate quantities of energy received or deliberated. In combustor, the gases form a semi transparent medium. Neglect of radiation in calculating the heat transfer is justifiable only for transparent gases like the nitrogen (N2), oxygen (O2) and hydrogen (H2). The species taking part in radiation are mainly the steam and the carbon dioxide, and then their participation in radiative transfer must be accounted for. In lower part of the temperature of dissociation, these products of combustion emit and absorb the electromagnetic radiation in a multitude of very narrow spectral lines, which can be superimposed to form the bands known as vibro-rotational. The spectrum is located near the infrarouge, this strong dependence of the radiative properties at the composition and at the temperature of the medium increases the difficulty of the problem and especially in rather complex geometries. In this paper, the chosen semi-transparent medium is the overheated pure water steam that is considered like a non-gray gas, a fine study of its radiative properties has been achieved using a narrow-band model.
Copyright © 2008 Praise Worthy Prize S.r.l. -
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Keywords:
Narrow-band model, Coupled radiation-conduction, Non-gray gas, Semi-transparent medium, Spherical geometry.
Structural and Magnetic Study of a Metal Excess Spinel: Cul.l5Crl.15Zr0.85Se4
by K. Belakroum, Z. Ouili, Ph. Molinie, A. Leblanc-Soreau
Abstract -
The compound Cul.l5Crl.15Zr0.85Se4 has been studied by X-ray diffraction. It belongs to the spinel structural type, but the formula indicates a copper excess with respect to the ideal spinel composition. The spinel structure was confirmed by X-ray diffractometry technique. The lattice parameter a with an accuracy of ±0.003Å was determined using Bragg peaks of XRD pattern. The structural refinements have been performed according to the Rietveld method to the stoichiometric compound CuCrZrSe4. Chromium and tin are located on the 16d octahedral sites (B-sublattice of the spinel structure). Low field DC magnetization measurements (ZFC-FC measurements), magnetic hysterisis were performed by using SQUID magnetometer (the superconducting quantum interference device). The average effective magnetic moment is there equal to 4.25μB and 4.26μB/Cr-atom. In addition a successive magnetic transition suggesting spin-glass transition at low temperatures.
Copyright © 2008 Praise Worthy Prize S.r.l. -
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Keywords:
Cul.l5Crl.15Zr0.85Se4, CuCrZrSe4, XRD, spin-glass, DC measurements.
Explicit Classical-Mechanical Description of the State of a Body
by T. Vukelja
Abstract -
An alternative classical-mechanical description of the state of a body is discussed, the description that is expressed exclusively by the properties of the body. Such description requires the specification of the “position in time” and the energy of the body, and implies the inclusion of the corresponding dynamical variables Qt and E into the formalism of classical mechanics. These variables constitute the conjugated pair with respect to the suitably generalized Poisson bracket. The results of the paper can be used for the consistent integration of the indeterminacy relation for position in time and energy into the formalism of quantum mechanics.
Copyright © 2008 Praise Worthy Prize S.r.l. -
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Keywords:
Classical mechanics, quantum mechanics, the state of a body, time, the indeterminacy relation for time and energy.
Surface SFAP Signal Generated in a Planar Space Invariant Volume Conductor as a Function of the Physiological Parameters
by B. Belhouki, N. Messaoudi
Abstract -
The electromyographic (EMG) signal represents the electrical variations of muscles activities. It can be detected on the skin surface above the aimed muscle. The analysis of influences of anatomical, physiological and detection system parameters on the shape of the surface EMG signal is more evident by using a single fibre action potential (SFAP). Modelling of surface SFAP is fondamental for the comprehension of the relationship between the internal anatomical and physiological parameters and the external caracteristics extracted from the recorded signal. In this work, surface SFAP signal has been generated in a planar, non homogeneous and anisotropic volume conductor constituted by muscle (anisotropic), fat and skin (isotropic) layers. The modelling of the signal has been realised by an analytical approach based on 2D Fourier transform properties. The potential is detected on the skin surface with a detection system which is constituted by a 1D and 2D spatial filters and a grid of nine point electrodes. We show in this work that the physiological parameters have strong influences on the shape of the detected signal and on their amplitude characteristics..
Copyright © 2008 Praise Worthy Prize S.r.l. -
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Keywords:
Action potential, Conductivity, Modelling, spatial filter.
Human Energy Harvesting for Wearable Computers
by A. C. Ammari, H. Hamouda
Abstract -
Nowadays, wearable computers are used in a variety of applications including health monitoring, remote check-up and rehabilitation. The use of these embedded systems can be extended to other applications where vital environmental or health conditions need to be remotely sensed. Despite the wide use of these systems, inadequate power supplies lead to engineering and design limitations and trade-offs. It is anticipated that with a properly managed renewable source of power, generated via habitual human motions, the use of wearable computers would increase at least ten fold. Currently, energy is derived from conventional systems based on rechargeable Lithium-Ion or Nickel-Cadmium batteries requiring a source of electricity. This paper first presents a review and survey of human-powered generations and conversion mechanisms. It also proposes a new power generation approach for wearable computers. This approach is based on the optimization of fabric garments made of piezoelectric new PVDF copolymer fibers that will transfer the human-supplied energy into an electric form. Based on an analytical approach maximizing the system's electric power output, these fibers will be spun (extruded), made into a fabric, and sewn into a garment.
Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved
Keywords:
Wearable computers, Human energy harvesting, Conversion mechanisms,
Piezoelectric,
PVDF
copolymer fibers, electric power.
Identification of Greenhouse Parameters Using ARMAX and NARMAX Structures
by B. Louhichi, A. Toumi
Abstract -
Greenhouse technology has evolved to create a favorable environment to cultivate a desirable crop year round. Of this fact, this paper presents a mathematical model for experimental validation of the thermal behavior in the greenhouse. In this study, it was investigated to what extend AutoRegressive Moving Average models with eXternal input (ARMAX) which could be used to describe the temperature and humidity of the interior air of the greenhouse. The nonlinear ARMAX or NARMAX model is also used to represent this nonlinear process. Both of these models of different AutoRegressive (AR), Moving Average (MA) and eXogenous (X) orders are proposed and their identifications are based on the Recursive Extended Least Square (RELS) method and the Neural Network (NN) method, respectively. An analysis of the computational results has confirmed that the NARMAX model and the NN method are superior to the ARMAX model and the RELS method in forgetting factor, as indicated by its Variance Accounted For (VAF).
Copyright © 2008 Praise Worthy Prize S.r.l. -
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Keywords:
ARMAX and NARMAX models; Recursive parameter estimation; Recursive extended least square; Neural networks; Greenhouse; Variance Accounted For (VAF).
The Finite Element
Method In Shielding Problems
by M. Lascu
Abstract
- A very powerful tool for studying the magnetic field of shaped slotted
screens has been developed. The proposed method is based on a circuital
characterization of the structure, via the Finite Element Method (FEM), which is
then combined with a modal expansion to compute the field inside and outside the
envelope. Although my analysis is focused in square slotted structures, the
versatility of the Finite Element Method permits one to apply this method to any
bidimensional envelope no matter how many slots or dielectric parts it contains.
This paper is also a review describing the basics of the finite-element method
and its applications to EMI/C problems. It demonstrates how this method can help
in the analysis of shield degradation in the presence of external conductors and
electromagnetic leakage through slot configurations in a shielded enclosure. The
development is given for an EMI application related to shield degradation in the
presence of external conductors. The magnetic field inside and outside the
slotted screens has been studied using the Finite Element Method. As a practical
application, the magnetically performance of a slotted cylindrical and
rectangular screen has been studied. In general, it is shown that coupling to
the interior of slotted screens is maximized at frequencies corresponding to
resonance of the shorted screen, provided that the fields do not vanish near the
aperture.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Aperture,
Finite Element Method, Grid, Mesh, Shield, Source.
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