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The study concerns an autonomous individual solar water heater installed in the Oran region in Algeria. Supplied by two sources of solar thermal and photovoltaic energy, this solar water heater provides domestic hot water for the needs of an average family of 6 people. A comparative approach was made to find the most adequate solution between increasing the surface area of the thermal solar panel or those of the photovoltaic panels, by analyzing the solar fraction and the efficiency of the thermal panels. The choice was make for a thermal panel with a surface area of 4 m2 and complete with 16 photovoltaic panels, thus resulting in a total surface area of 14 m2 to obtain an autonomous solar water heater powered only by solar energy. Another option was considered by incorporating a photovoltaic thermal panel, and substantial savings were found.

A critical problem in the application of metal matrix composites is the presence of high residual thermal stresses induced during the development process. These thermally induced stresses are generally detrimental to the service life of this type of composite. This article discusses the influence of maximum residual stresses on the intensity factor. The results interpreted in terms of damage, allowed us to identify the risk zones; characterized by a significant level of maximum residual stresses (S11Max, S22Max, S33Max), namely the particle/Matrix interface. The results also show that the loading conditions and the inter-distance between matrix and particle with two interfacial cracks have an important effect on max residual stresses and stress intensity factors.

Technology-mediated education or e-learning is growing globally both in scale and delivery capacity due to the large diffusion of the ubiquitous information and communication technologies (ICT) in general and the web technologies in particular. This statement has not yet been fully supported by research, especially in developing countries such as Algeria. The purpose of this paper was to identify directions for addressing the needs of academics in higher education institutions in Algeria in order to adopt the e-learning approach as a strategy to improve quality of education. The paper will report results of an empirical study that measures the readiness of the Algerian higher education institutions towards the implementation of ICT in the educational process and the attitudes of faculty members towards the application of the e-learning approach in engineering education. Three main objectives were targeted, namely: (a) to provide an initial evaluation of faculty members' attitudes and perceptions towards web-based education; (b) reporting on their perceived requirements for implementing e-learning in university courses; (c) providing an initial input for a collaborative process of developing an institutional strategy for e-learning. Statistical analysis of the survey results indicates that the Algerian higher education institution, which adopted the Licence-Master and Doctorate educational system, is facing a big challenge to take advantage of emerging technological innovations and the advent of e-learning to further develop its teaching programmes and to enhance the quality of education in engineering fields. The successful implementation of this modern approach is shown to depend largely on a set of critical success factors that would include: The extent to which the institution will adopt a formal and official e-learning strategy. The extent to which faculty members will adhere and adopt this strategy and develop ownership of the various measures in the context of their teaching and research responsibilities. The extent to which the university will offer adequate support in terms of training, software platform administration, online resource development and impact monitoring and assessment. (Contains 4 tables and 11 figures.)

The phase change materials (PCM) are widely used in several applications, especially in the latent heat thermal energy storage system (LHTESS). Due to the very low thermal conductivity of PCMs. A small mass fraction of hybrid nanoparticles TiO2-CuO (50%-50%) is dispersed in PCM with five mass concentrations of 0%, 0.25%, 0.5%, 0.75% and 1 mass % to improve its thermal conductivity. This article is focused on thermal performance of the hybrid nano-PCM (HNPCM) used for the LHTESS. A numerical model based on the enthalpy-porosity technique is developed to solve the Navier-Stocks and energy equations. The computations were conducted for the melting and solidification processes of the HNPCM in a shell and tube latent heat storage (LHS). The developed numerical model was validated successfully with experimental data from the literature. The results showed that the dispersed hybrid nanoparticles improved the effective thermal conductivity and density of the HNPCM. Accordingly, when the mass fraction of a HNPCM increases by 0.25%, 0.5%, 0.75% and 1 mass %, the average charging time improves by 12.04 %, 19.9 %, 23.55%, and 27.33 %, respectively. Besides, the stored energy is reduced by 0.83%, 1.67%, 2.83% and 3.88%, respectively. Moreover, the discharging time was shortened by 18.47%, 26.91%, 27.71%, and 30.52%, respectively. [ABSTRACT FROM AUTHOR]

Solar energy is one of the most attractive renewable energy sources due to its abundance in our country. However, despite the specificities of the region of Ain-Defla that can be used to reduce the use can't be supported by the state. In this case, the contribution of solar energy could effectively contribute in solving some energy problems. Current systems are mainly based on the technology known as the "parabolic trough power plant" which uses a long rectangular mirror and a parabolic trough. The solar rays are reflected by the mirror to converge on the tube which is placed at the focal line of a parabolic trough concentrator; this system has an excellent power generation, it's non-polluting, and silent. In that respect, this research aims to study the performance improvement of a parabolic trough. Several techniques exist to ensure the high temperature at the outlet, for the optimization is compatible with the software called "Engineering equation Solver" (EES). [ABSTRACT FROM AUTHOR]

A two-dimensional (2D) numerical model was used to simulate the use of a phase change material linked to a PV system to control the temperature rise of the PV cells. The predicted temperatures using the 2D model have been compared with experimental and numerical data of the literature and a good agreement was obtained for both the isotherm contours and time evolution of the temperature. An extended surface (fins) has been used in order to improve conductive heat transfer and to reinforce the thermal homogeneity. Concerning the inner fins included on the PV panel (Front), the obtained results show that these fins reduce significantly the temperature. Furthermore, the configurations of L = 25, 30 and 35 mm allow better cooling of the PV panel. On the other hand, the back inner fin used reduces dramatically the performance of the PV/PCM system for cooling the panel. [ABSTRACT FROM AUTHOR]

This paper presents a numerical investigation of a two-dimensional (2D) oscillatory flow around a cylinder of different elliptic ratios, in order to study the effect of the elliptic form of the cylinder on the vorticity field and the hydrodynamic forces that act on it. The elliptic ratio ε was varied from 1 to 0.1, where the small axis is parallel to the flow direction, simulating cases ranging from a circular cylinder to the case of a cylinder with a profited elliptic section. The investigations presented here are for Reynolds number Re = 100 and Keulegan number KC= 5 . The numerical visualization of the flow for different elliptic ratios shows five different modes of vortex shedding (symmetric and asymmetric pairing of attached vortices, single-pair, double-pair, and chaotic), which depend on the range of the elliptic ratio. The results show that the longitudinal force increases with the reduction of the elliptic ratio. The transverse force appears from the elliptic ratio ε = 0.75 and increases with the reduction of this ratio in the range of 0.75 ≥ε≥ 0.4, then decreases for ε < 0.4. On the other hand, concerning the Morison coefficients the results show that the drag coefficient is sensitive to the swirling layout while the coefficient of inertia does not seem to be much affected by the geometry of the cylinder [ABSTRACT FROM AUTHOR]

The present paper presents an investigation to study of AC electrokinetic phenomena in microfluidics. The results show that the variation of the width of electrodes and the gap between electrodes has no effect on the results, but if we change the height of the microcantilver, the concentration of the bonded molecules exchanged with a proportional manner and the width of reaction surface has an effect inversely proportional to the results. The results show also that increasing the length of reaction surface has a negative effect on the attachment of molecules on the surface reaction and changing the width of electrodes or the gap between electrodes changes the concentration of the bonded molecules. The present numerical results can be considered as a contribution to the design of the microchannel used in lab-on-a-chip applications. [ABSTRACT FROM AUTHOR]

The present paper describes the analysis and the implementation of simple wall models for Large Eddy Simulations of high Reynolds numbers flows. The comparison with direct numerical simulation (DNS) in channel flow at Retϒ=950 was carried out. The results obtained from wall models compare well with numerical data. [ABSTRACT FROM AUTHOR]