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Constantine, Algeria

Athmania D.,University of Tebessa | Achour H.,University of Sfax
Remote Sensing | Year: 2014

Digital Elevation Models (DEMs) including Advanced Spaceborne Thermal Emission and Reflection Radiometer-Global Digital Elevation Model (ASTER GDEM), Shuttle Radar Topography Mission (SRTM), and Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010) are freely available for nearly the entire earth's surface. DEMs that are usually subject to errors need to be evaluated using reference elevation data of higher accuracy. This work was performed to assess the vertical accuracy of the ASTER GDEM version 2, (ASTER GDEM2), the Consultative Group on International Agriculture Research-Consortium for Spatial Information (CGIAR-CSI) SRTM version 4.1 (SRTM v4.1) and the systematic subsample GMTED2010, at their original spatial resolution, using Global Navigation Satellite Systems (GNSS) validation points. Two test sites, the Anaguid Saharan platform in southern Tunisia and the Tebessa basin in north eastern Algeria, were chosen for accuracy assessment of the above mentioned DEMs, based on geostatistical and statistical measurements. Within the geostatistical approach, empirical variograms of each DEM were compared with those of the GPS validation points. Statistical measures were computed from the elevation differences between the DEM pixel value and the corresponding GPS point. For each DEM, a Root Mean Square Error (RMSE) was determined for model validation. In addition, statistical tools such as frequency histograms and Q-Q plots were used to evaluate error distributions in each DEM. The results indicate that the vertical accuracy of SRTM model is much higher than ASTER GDEM2 and GMTED2010 for both sites. In Anaguid test site, the vertical accuracy of SRTM is estimated 3.6 m (in terms of RMSE) 5.3 m and 4.5 m for the ASTERGDEM2 and GMTED2010 DEMs, respectively. In Tebessa test site, the overall vertical accuracy shows a RMSE of 9.8 m, 8.3 m and 9.6 m for ASTER GDEM 2, SRTM and GMTED2010 DEM, respectively. This work is the first study to report the lower accuracy of ASTER GDEM2 compared to the GMTED2010 data. © 2014 by the authors. Source

Soltani M.R.,University of Tebessa | Bouchair A.,University Blaise Pascal | Mimoune M.,University of Mentouri Constantine
Journal of Constructional Steel Research | Year: 2012

A numerical model is developed to predict the behavior of castellated beams with hexagonal and octagonal openings up to failure. The numerical model takes into account both material and geometric nonlinearities. To initiate buckling, an initial small out-of-plane geometric imperfection, obtained from an eigenvalues buckling analysis, was imposed to the model. Results of experimental data obtained from previous works have shown that the model is able to predict, with good accuracy, the ultimate load and to some extent the mode of failure. A parametric study is then realized to assess the cross-section classification given in the Annex N and to compare between the ultimate load behavior of castellated beams with hexagonal and octagonal openings when subjected to flexure and shear force. The numerical results have been compared with those obtained with the design method presented in ENV1993-1-1 Annex N. © 2011 Elsevier Ltd. All rights reserved. Source

Latreche S.,University of Tebessa | Schaper F.,University of Montreal
Inorganica Chimica Acta | Year: 2011

Reaction of the lithium salts of N,N′-dialkyl-2-amino-4-imino-pent-2- enes, nacnacRLi(THF) (R = CH2Ph, Cy, nPr, iBu or S-CH(Me)Ph), with half an equivalent of CrCl2(THF)x yielded the homoleptic complexes (nacnacR)2Cr. All complexes were characterized by X-ray diffraction studies and displayed a highly symmetric, square-planar coordination around the chromium center with strong boat-like distortions of the diketiminate ligands. Reaction of nacnac RLi(THF) (R = CH2Ph, Cy) with one equivalent of CrCl 2(THF)x afforded the dimeric complexes {nacnac RCr(μ-Cl)}2. © 2010 Elsevier B.V. All rights reserved. Source

Boumali A.,University of Tebessa
Electronic Journal of Theoretical Physics | Year: 2015

In this paper, we want to improved the calculations of the thermodynamic quantities of the relativistic Harmonic oscillator using the Hurwitz zeta function. The comparison of our results with those obtained by a method based on the Euler-MacLaurin approach has been made. © Electronic Journal of Theoretical Physics. Source

Mesloub S.,King Saud University | Mesloub S.,University of Tebessa
Mathematical Methods in the Applied Sciences | Year: 2010

In this paper, we study a nonlocal mixed problem for a nonlinear hyperbolic equation. Based on some a priori estimates and some density arguments, we prove the well posednessof the associated linear problem. The existence and uniqueness of the weak solution of the nonlinear problem are then established by applying an iterative process based on the obtained results for the linear problem. Copyright © 2009 John Wiley & Sons, Ltd. Source

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