112 research outputs found
Remerciements
No full textMes premiers remerciements vont aux Aït Ba’amran qui m’ont ouvert leurs portes, leurs espaces de vie, leurs mémoires et parfois leurs archives. Je pense tout particulièrement à la famille Bounnit, à la famille Zaboun, à Larbi El Kha, à Ta’achro et à Mbark Aroal. Ce travail doit aussi beaucoup à la confiance et à l’amitié complice de Aissa Derhem, mon ami poète, de Abdallah Ouhna au regard éloigné, de Mohammed Bounit et de Brahim Boughalid, qui m’ont révélé les secrets de leurs terroirs, et de..
Morphology, Photoluminescence and Photovoltaic Properties of Laser Processed ZnO/carbon Nanotube Nanohybrids
No full textGPU-accelerated CFD Simulations for Turbomachinery Design Optimization
No full textDesign optimization relies heavily on time-consuming simulations, especially when using gradient-free optimization methods. These methods require a large number of simulations in order to get a remarkable improvement over reference designs, which are nowadays based on the accumulated engineering knowledge already quite optimal.High-Performance Computing (HPC) is essential to reduce the execution timeof the simulations. While parallel programming using the CPU is established since more than two decades, the use of accelerators, such as the Graphics Processing Unit (GPU), is relatively recent in design optimization. The GPU has actually a huge computational power comparable to a many-core cluster but concentrated in one device. This raw power is not easy to utilize as entire code parts have to be rewritten using a GPU programming language. Even though high-level standards (e.g. openACC) are able to bring a basic acceleration with a low development effort, it is not simple to get large speedups with these methods. Low-level programming languages are more efficient but different speedups are reported and there is a need fora deep analysis to make the GPU potential more transparent to scientists especially non-experts in HPC.In order to study the GPU acceleration for CFD steady simulations, two in-house CFD solvers have been ported to the GPU; one with explicit and the second with implicit time-stepping. After the porting and the validation of the GPU solvers, the GPU code optimization leads to the identification of a set of key parameters affecting the GPU efficiency. At the same time, both methods have been compared resulting into a performance model and a classification of the GPU acceleration of some CFD operations. The purpose is to enable scientists to take an educated decision concerning the GPU porting of their CPU applications by providing an expected GPU speedup.In addition to the two GPU CFD solvers that are now integrated into the in-house design optimization software package, this research provided key elements to reduce the ambiguity about the GPU potential, namely a qualitative analysis and a classification. These tools can help selecting the best candidate for a breakthrough in CFD acceleration. At the same time, this work identified serious limitations in the preconditioning of a linear system of equations and the limit of today iterative matrix factorization methods in terms of stability and convergence. There is a need for a paradigm shift toward inherently parallel preconditioners. The developed tools have been used for the optimization of a compressor and a turbine cascade resultinginto a faster optimization process on the GPU
Conception simulation et amélioration de performance d’une turbo foreuse
No full text113 p. : ill. ; 30 cmLa Turbo foreuse est un moteur hydraulique utilisé pour le forage de puits vertical ou horizontal de pétrole et de gaz, et aussi un type de turbomachines hydrauliques axiales, la section motrice de turbine a plusieurs étages de stators et rotors. Elle convertit la puissance hydraulique fournie par le fluide de forage, sous la forme de pression et de débit en énergie mécanique sous forme de rotation. L'efficacité de la turbo foreuse est dépendante de la forme des aubes, ces derniers sont les composants hydrauliques les plus importants, par conséquence, il est important d'analyser l'impact du liquide de forage sur les aubes de la turbo foreuse. Ce projet représente une méthodologie pour la conception de la section motrice à plusieurs étages de la turbo foreuse, cette méthodologie de l'étude sera basée sur l'utilisation d'une simulation avec logiciel ANSYS qui utilise les outils : BLADEGEN, TURBO-GRID, CFX, CFD, Static Structural et FSI
Electron-Beam-Evaporated Nickel Oxide Thin Films for Application as a Hole Transport Layer in Photovoltaics
No full textWe present the growth of nickel oxide (NiO) thin films as a hole transport material in photovoltaic devices using the e-beam evaporation technique. The metal oxide layers were reactively deposited at a substrate temperature of 200 °C using an electron beam evaporator under an oxygen atmosphere. The oxide films reactively grown through electron-beam evaporation were optimized for carrier transport layers. Optical and structural characterizations were performed using ultraviolet–visible (UV–Vis) spectrometry, X-ray diffraction, contact angle measurements, scanning electron microscopy, and Hall effect measurements. The study of these films confirmed that the NiO layer is a suitable candidate for use as a hole transport layer based on Hall effect measurements. A morphological study using field-emission scanning electron microscopy confirmed the growth of compact, uniform, and defect-free metal oxide layers. Contact angle measurements revealed that the films possessed semi-hydrophilic properties, contributing to improved stability by repelling water from their surfaces. The stoichiometry of the films was influenced by the oxygen pressure during deposition, which affected both their morphological and optical features. The NiO films exhibited a transmittance exceeding 80% in the visible spectrum. These findings highlight the potential applications of such nickel oxide films as hole transport material layers
Usability of Rich Internet Applications
No full textThis thesis reports the outcome of a study that is performed for Info Support. Info Support is a software house that is interested in new technologies. Unit finance and insurance is interested in the usability of Rich Internet Applications. Rich Internet Applications are new kind of web applications that offer more possibilities to design user friendly and attractive graphical user interface (GUI) that is comparable to the GUI of desktop applications. To investigate if the usability of the Rich Internet Application is indeed better then the traditional web application, two car insurance web applications are built as a proof of concept. These web applications are built with the same usability principles and have the same content and functionalities. The only difference is the technology that is used for building the web applications. The RIA is built with JavaFX and the traditional web application with PHP/HTML. These two applications are tested in an experiment where 26 participants with different ages and sex have tested two web applications in a lab. The results of this experiment is statistically analyzed to find dependency. From the analysis we have found that the satisfaction is significant for the tested web applications and therefore we can conclude that the usability of the Rich Internet Applications is indeed more usable than the traditional web application. This finding can be useful for finance and insurance companies to convert their web applications into RIA to attract more clients to buy their products.Media knowledge engineeringElectrical Engineering, Mathematics and Computer Scienc
Well-posedness and energy decay for Timoshenko systems with discrete time delay under frictional damping and/or infinite memory in the displacement
No full textInternational audienceIn this paper, we consider a vibrating system of Timoshenko-type in a bounded one-dimensional domain with discrete time delay and complementary frictional damping and infinite memory controls all acting on the transversal displacement. We show that the system is well-posed in the sens of semigroup and that, under appropriate assumptions on the weights of the delay and the history data, the stability of the system holds in case of the equal-speed propagation as well as in the opposite case in spite of the presence of a discrete time delay, where the decay rate of solutions is given in terms of the smoothness of the initial data and the growth of the relaxation kernel at infinity. The results of this paper extend the ones obtained by the present author and Messaoudi in (Acta Math Sci 36:1–33, 2016) to the case of presence of discrete delay
Computational Screening of Metal-Organic Frameworks for Carbon Capture: Insights from Flue Gas and Direct Air Capture Condition
No full textMetal-organic frameworks (MOFs) have emerged as highly promising materials for carbon dioxide (CO2) capture, owing to their exceptional tunability, high surface areas, and versatile chemical properties. In this study, we employ Grand Canonical Monte Carlo (GCMC) simulations to systematically screen 1,670 experimentally synthesized MOFs from the CoRE database, focusing on their potential for carbon capture applications. The screening process prioritizes flue gas conditions (0.15 bar CO2, 298 K), identifying MOFs with CO2 adsorption capacities exceeding 0.16 g/g and heats of adsorption below 40 kJ/mol. Among the screened materials, 18 structures met these criteria, with the majority featuring open metal sites (OMS); a key structural feature that enhances CO₂ binding affinity. To further evaluate the versatility of MOFs, some MOFs were also selected from results of flue gas screening and tested under direct air capture (DAC) conditions (285 K, 400 ppm CO2). Remarkably, 18 out of the 20 MOFs demonstrated CO₂ adsorption capacities above 1 mmol/g, with some achieving capacities as high as 4 mmol/g. The study emphasizes the critical role of structural and chemical properties, particularly the presence of OMS and functional groups, in determining adsorption performance. By providing a rapid and efficient computational screening approach, this work offers valuable insights into identifying high-performing MOFs tailored to both flue gas and DAC applications
Design and implementation of three-level inverter for grid-tied PV systems
No full textHigh quality voltage and current are required when PV generator is connected to grid utility. To this, multilevel inverters are very desirable to be used as connection interface. To keep the cost of the whole system as low as possible, a cost-effective control device using STM32F4 discovery board is employed to control three-level inverter that can be used in grid-tied PV system. The paper develops and implements the control strategy of simplified space vector pulse width modulation (SVPWM) algorithm using Matlab/Simulink software. Obtained experimental results depict the powerfulness of used card as well as the high quality of the delivered powerDOI: 10.1109/ICEE-B.2017.819199
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