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匹配条件: “Abdelaziz Boudlal” ,找到相关结果约337条。
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Modulation Equations for Roll Waves on Vertically Falling Films of a Power-Law Fluid  [PDF]
Abdelaziz Boudlal, Valery Liapidevskii
World Journal of Mechanics (WJM) , 2012, DOI: 10.4236/wjm.2012.21001
Abstract: Waves of finite amplitude on a thin layer of non-Newtonian fluid modelled as a power-law fluid are considered. In the long wave approximation, the system of equations taking into account the viscous and nonlinear effects has the hyper- bolic type. For the two-parameter family of periodic waves in the film flow on a vertical wall the modulation equations for nonlinear wave trains are derived and investigated. The stability criterium for roll waves based on the hyperbolicity of the modulation equations is suggested. It is shown that the evolution of stable roll waves can be described by self-similar solutions of the modulation equations.
Modeling of Video Sequences by Gaussian Mixture: Application in Motion Estimation by Block Matching Method
Boudlal Abdenaceur,Nsiri Benayad,Aboutajdine Driss
EURASIP Journal on Advances in Signal Processing , 2010,
Abstract: This article investigates a new method of motion estimation based on block matching criterion through the modeling of image blocks by a mixture of two and three Gaussian distributions. Mixture parameters (weights, means vectors, and covariance matrices) are estimated by the Expectation Maximization algorithm (EM) which maximizes the log-likelihood criterion. The similarity between a block in the current image and the more resembling one in a search window on the reference image is measured by the minimization of Extended Mahalanobis distance between the clusters of mixture. Performed experiments on sequences of real images have given good results, and PSNR reached 3 dB.
Modeling of Video Sequences by Gaussian Mixture: Application in Motion Estimation by Block Matching Method
Abdenaceur Boudlal,Benayad Nsiri,Driss Aboutajdine
EURASIP Journal on Advances in Signal Processing , 2010, DOI: 10.1155/2010/210937
Abstract: This article investigates a new method of motion estimation based on block matching criterion through the modeling of image blocks by a mixture of two and three Gaussian distributions. Mixture parameters (weights, means vectors, and covariance matrices) are estimated by the Expectation Maximization algorithm (EM) which maximizes the log-likelihood criterion. The similarity between a block in the current image and the more resembling one in a search window on the reference image is measured by the minimization of Extended Mahalanobis distance between the clusters of mixture. Performed experiments on sequences of real images have given good results, and PSNR reached 3 dB.
Constraints Based Decision Support for Site-Specific Preliminary Design of Wind Turbines  [PDF]
Abdelaziz Arbaoui, Mohamed Asbik
Energy and Power Engineering (EPE) , 2010, DOI: 10.4236/epe.2010.23024
Abstract: This study presents a decision-support tool for preliminary design of a horizontal wind turbine system. The function of this tool is to assist the various actors in making decisions about choices inherent to their activities in the field of wind energy. Wind turbine cost and site characteristics are taken into account in the used models which are mainly based on the engineering knowledge. The present tool uses a constraint-modelling technique in combination with a CSP solver (numerical CSPs which are based on an arithmetic interval). In this way, it generates solutions and automatically performs the concept selection and costing of a given wind turbine. The data generated by the tool and required for decision making are: the quality index of solution (wind turbine), the amount of energy produced, the total cost of the wind turbine and the design variables which define the architecture of the wind turbine system. When applied to redesign a standard wind turbine in adequacy with a given site, the present tool proved both its ability to implement constraint modelling and its usefulness in conducting an appraisal.
Calculation of Atomic Data and Gain Coefficient for XUV & Soft X-Ray Laser Emission from Ge XXIII  [PDF]
Wessameldin S. Abdelaziz
Optics and Photonics Journal (OPJ) , 2014, DOI: 10.4236/opj.2014.49025
Abstract: Energy levels, transition probabilities, oscillator strengths, and collision strengths have been calculated for transitions in Ne-like Ge. The data refer to a 241 fine-structure levels belonging to the configurations 1s2 2s2 2p5nl, 1s2 2s1 2p6nl (n = 3, 4, 5, 6; l = s, p, d, f, g and h), which have been calculated by the fully relativistic flexible atomic code (FAC). These data are used in the determination of the reduced population for the 241 fine structure levels and gain coefficients over a wide range of electron densities (from 2 × 10+20 to 4 × 10+22 cm-3) and at various electron plasma temperatures (650, 850, 1050, 1250, 1450, 1650, 1850) eV by using the MATLAB R2013a Computer program for solving simultaneous coupled rate equations. The reduced population for the 241 fine structure levels the gain coefficients for those transitions with positive population inversion factor are determined and plotted against the electron density.
Immersive Learning Design (ILD): A New Model to Assure the Quality of Learning through Flipped Classrooms  [PDF]
Hamdy A. Abdelaziz
Open Journal of Social Sciences (JSS) , 2014, DOI: 10.4236/jss.2014.211027
Abstract: The objective of this paper was to develop an immersive Web-based learning model to assure the quality of learning through the flipped classrooms. The proposed model was guided theoretically by the flipped classroom as a new Web-based learning trend/system. It was also guided pedagogically by active and reflective learning principles that support transforming of the teaching and learning practices from content engagement to cognitive engagement. The targeted immersive learning model encompasses four reciprocal phases: Pro-act, Act, Reflect, and Re-act (PARR). To validate the suggested model, a convenience sample of graduate students studying an advanced statistics course was selected from the Distance Teaching and Training Program at Arabian Gulf University. After designing and applying this new immersive Web-based learning model (PARR), findings revealed that using the flipped classroom through this immersive Web-based learning model has a statistical and practical impact on developing achievement and self-study skills among graduate students. The contribution of this research is that it qualifies the Web-based instructional practices to shift from content acquisition act to knowledge expression and creation act. In addition, the paper will be of benefit to people looking for pedagogical applications of virtual and blended learning environments for developing multiple ways to express what learners know and be able to do.
Bandwidth Enhansment of Microstrip Antenna
Abdelmonem Abdelaziz Abdelaziz
PIER , 2006, DOI: 10.2528/PIER06053001
Abstract: A novel microstrip antenna with wide bandwidth is presented. Two different radiating elements connected together through a matched section and are embedded on a single layer structure. This new structure offers a dual-band microstrip antenna. By controlling the two resonance frequencies of the two elements, a wide frequency bandwidth of approximately 9% has been achieved. A more bandwidth enhancement, up to 12%, has been achieved by adding two parasitic elements to one element of the proposed antenna. Fabrication and measurement of S for the proposed antenna has been done. The measured results have been compared with the simulated results using commercial software HFSS version-8.0.
Improving the Performance of an Antenna Array by Using Radar Absorbing Cover
Abdelmonem Abdelaziz Abdelaziz
PIER Letters , 2008, DOI: 10.2528/PIERL07112503
Abstract: Improving the performance of a microstrip antenna array has been considered based on the innovative use of an absorbing radar cover.Since the surface wave between antennas array elements plays a major role in mutual coupling and scattering behavior of array antenna. The main objective of this work is to reduce the effect of surface wave between array elements using radar absorbing cover.The absorbing cover has been designed with spatial configuration to get maximum performance at the resonant frequency of the fabricated microstrip antenna array.The measured results of the tested antenna array show a significant reduction of both mutual coupling between array patches and radar cross section of the tested antenna array with minimum side effects on the antenna parameters.
A Novel Technique for Improving the Performance of Salisbury Screen
Abdelmonem Abdelaziz Abdelaziz
PIER Letters , 2008, DOI: 10.2528/PIERL07110104
Abstract: The most common and simple structure to reduce the level of the reflected power from a metallic surface is the single layer structure known as Salisbury screen which is a sheet of porous material impregnated with graphite and spaced a quarter-wavelength off a metallic backing plate. The main disadvantage of this mechanism is the narrow frequency bandwidth. Many techniques have been reported to improve the working frequency bandwidth but with some degradation in the other technical properties of the overall structure. In this paper a novel technique has been introduced based on a spatial kind of material called circuit analog screen. Theoretical analysis shows that the bandwidth of the reflected power will be improved if the graphite sheet of Salisbury screen has been loaded by circuit analog screen with spatial geometry with spatial parameters.
A Hierarchical Methodology for Performance Evaluation Based on Data Envelopment Analysis: The Case of Companies’ Competitiveness in an Economy  [PDF]
Mohamed Dia, Fouad Ben Abdelaziz
American Journal of Operations Research (AJOR) , 2011, DOI: 10.4236/ajor.2011.13015
Abstract: In this research, we present a hierarchical Data Envelopment Analysis (DEA) methodology for competitiveness analysis. This methodology takes into account the heterogeneity of the decision making units (DMUs) as well as the diversity of the comparison criteria. We propose to homogenize the DMUs by grouping them hierarchically, which permits a better identification and definition of the criteria in each specific grouping. The methodology proceeds first by the determination of the performances or relative efficiencies, which are in turn aggregated into competitiveness indices in each grouping by the superiority index of [1]; then, the overall competitiveness indices are determined additively along the hierarchical levels. We illustrate the methodology by a competitiveness analysis of several companies belonging to different sectors of activity in an economy, where are suggested ways of improvement for the non-competitive companies within their sectors and within the economy.
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