51 research outputs found

    Image Registration Methode in Radar Interferometry

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    This article presents a methodology for the determination of the registration of an Interferometric Synthetic radar (InSAR) pair images with half pixel precision. Using the two superposed radar images Single Look complexes (SLC) [1-4], we developed an iterative process to superpose these two images according to their correlation coefficient with a high coherence area. This work concerns the exploitation of ERS Tandem pair of radar images SLC of the Algiers area acquired on 03 January and 04 January 1994. The former is taken as a master image and the latter as a slave image

    The Casimir force in noncommutative Randall-Sundrum models

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    In this paper we study the effect of spacetime noncommutativity in the 5-dimensional Randall-Sundrum brane worlds on the Casimir force acting on a pair of parallel plates. We show that the presence of a noncommutative scale length affects the nature of the Casimir force for small plate separation. Using accurate experimental bounds for the Casimir force in parallel plate geometry, we find an upper bound for the noncommutative cutoff of the order of 10310^{3} TeV, and that the size of the interbrane distance in RSI model is approximately given by kR≲20.5kR\lesssim20.5 and kR≲18.4kR\lesssim18.4 for k=1019k=10^{19} GeV and k=1016k=10^{16}GeV, respectively.Comment: 20 pages, 5 figures, accepted for publication in Phys. Rev.

    Fuzzy extended Kalman filter for dynamic mobile localization in urban area using wireless network

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    The problem of accurate mobile positioning in cellular network is very challenging and still subject to intensive research, especially given the uncertainty pervading the signal strength measurements. This paper advocates the use of fuzzy based reasoning in conjunction with Kalman filtering like approach in order to enhance the localization accuracy. The methodology uses TEMS Investigation software to retrieve network information including signal strength and cell-identities of various base transmitter stations (BTS). The distances from the mobile station (MS) to each BTS are therefore generated using Walfish-Ikigami radio propagation model. The performances of the established hybrid estimator −fuzzy extended Kalman filter (FEKF)- are compared with extended Kalman filter approach and fuzzy-control based approach. Both simulation and real-time testing results demonstrate the feasibility and superiority of the FEKF localization based approach

    Effect of Minimal lengths on Electron Magnetism

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    We study the magnetic properties of electron in a constant magnetic field and confined by a isotropic two dimensional harmonic oscillator on a space where the coordinates and momenta operators obey generalized commutation relations leading to the appearance of a minimal length. Using the momentum space representation we determine exactly the energy eigenvalues and eigenfunctions. We prove that the usual degeneracy of Landau levels is removed by the presence of the minimal length in the limits of weak and strong magnetic field.The thermodynamical properties of the system, at high temperature, are also investigated showing a new magnetic behavior in terms of the minimal length.Comment: 14 pages, 1 figur

    Entropy of the Randall-Sundrum black brane world to all orders in the Planck length

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    We study the effects, to all orders in the Planck length from a generalized uncertainty principle (GUP), on the statistical entropy of massive scalar bulk fields in the Randall-Sundrum black brane world. We show that the Bekenstein-Hawking area law is not preserved, and contains small corrections terms proportional to the black hole inverse area.Comment: 19 pages, 1 figure. (v2): section 4 improve

    Hawking radiation and thermodynamics of dynamical black holes in phantom dominated universe

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    The thermodynamic properties of dark energy-dominated universe in the presence of a black hole are investigated in the general case of a varying equation-of-state-parameter w(a)w(a). We show that all the thermodynamics quantities are regular at the phantom divide crossing, and particularly the temperature and the entropy of the dark fluid are always positive definite. We also study the accretion process of a phantom fluid by black holes and the conditions required for the validity of the generalized second law of thermodynamics. As a results we obtain a strictly negative chemical potential and an equation-of-state parameter w<−5/3.w<-5/3.Comment: 22 pages,3 figure

    Hydroxyapatite-TiO2-SiO2-Coated 316L Stainless Steel for Biomedical Application

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    This study investigated the effectiveness of titania (TiO2) as a reinforcing phase in the hydroxyapatite (HAP) coating and silica (SiO2) single-layer as a bond coat between the TiO2-reinforced hydroxyapatite (TiO2/HAP) top layer and 316L stainless steel (316L SS) substrate on the corrosion resistance and mechanical properties of the underlying 316L SS metallic implant. Single-layer of SiO2 film was first deposited on 316L SS substrate and studied separately. Water contact angle measurements, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectrophotometer analysis were used to evaluate the hydroxyl group reactivity at the SiO2 outer surface. The microstructural and morphological results showed that the reinforcement of HAP coating with TiO2 and SiO2 reduced the crystallite size and the roughness surface. Indeed, the deposition of 50 vol. % TiO2-reinforced hydroxyapatite layer enhanced the hardness and the elastic modulus of the HAP coating, the introduction of SiO2 inner-layer on the surface of the 316L SS allowed the improvement of the bonding strength and the corrosion resistance as confirmed by scratch studies, nanoindentation and cyclic voltammetry tests

    Signal processing techniques for the ultrasound characterization of complex materials

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    International audienceThis article focuses on the application of different signal processing techniques to improve the visibility of the echoes during travel time between the echo of entry (opposite echo), and the back wall echo (back surface) of longitudinal and transverse waves, it is easy to calculate the speed and longitudinal cross respectively, and then determine the elastic constants (Young modulus, Poisson’s ratio,) that allow us to describe the development of properties and split spectrum processing method
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