M. HAMRIT Farrah

Solar energy is the umbrella term for all processes that use local solar air heating. Energy-efficient construction techniques for lighting, heating, and cooling are directly related to it. The objective is to use renewable energy sources to lower total energy consumption.

The A particular kind of solar system known as a solar air heater (SAH) converts the sun energy into heat. In our work we use the innovation of the experimental solar air heater,
such as the use of an unstable turbulent flow. The system under discussion comprises of two solar air heater tubes that are connected by an absorber and each operated by a delivery-mode fan that is inserted in one of the insulation's intake holes. The glass that hangs on the front of this system contains an absorber. It is connected to the box prototype via a pipe on the glass side. The heated air is blowing toward the box prototype. On the same face of the prototype box, there are two round holes. Hot air is supplied through the intake holes, and the outlet openings send hot air into the surrounding environment. Solving the Navier-Stokes equations associated with the standard k-ω turbulence model. And using the method of limited elements, these programs can be implemented on the basis of ANSYS Fluent 17.0 software

Anumerical study of the natural convection of steady-state laminar heat transfer in
a horizontal ring between a heated hexagonal inner cylinder and a cold hexagonal outer cylinder. A Cu - water
nanofluid traverses this annular space. The system of equations governing the problem was solved numerically
by the fluent calculation code based on the finite volume method. Based on the Boussinesq approximation. The
interior and exterior sides from the two cylinders are maintained at a fixed temperature. We investigated the
impacts of various thermal Rayleigh numbers (103≤ Rat ≤2.5x105
), and the volume fraction from the nanoparticles
(0≤ Ø ≤0.12) on fluid flow and heat transfer performance. It is found that in high thermal Rayleigh numbers, a
thin thermal boundary layer is illustrated at the flow that heavily strikes the ceiling and lower from the outer
cylinder. In addition, the local and mean Nusselt number from a nanofluid are enhanced by enhancing the volume
fraction of the nanoparticles.The results are shown within the figure of isocurrents, isotherms, and mean and local
Nusselt numbers. Detailed results of the numerical has been compared with literature ones, and it gives a reliable
agreement.

A NaCeP2O7 compound was successfully synthesized by a high-temperature reaction with the solid-state method. Analyzing the XRD pattern, of the studied compound, confirms the orthorhombic phase with the Pnma space group. The examination of SEM images reveals that the majority of grains are around 500 to 900 nm with a uniform distribution. As for the EDXS analysis, all chemical elements were detected and found in the appropriate ratio. The curves of temperature-dependent imaginary modulus M′′ versus angular frequency reveal the presence of one peak at each temperature, proving that the dominant contribution is associated with the grains. The frequency dependence of the conductivity of alternating current is explained using Jonscher's law. The close values of the activation energies obtained from the jump frequency and extracted from the dielectric relaxation of the modulus spectra, as well as from the continuous conductivity imply that the transport takes place by the Na+ ions hopping mechanism. The charge carrier concentration in the title compound has been evaluated and shown to be independent of temperature. The exponent s increases with the increase in temperature; this behavior proves that the non-overlapping small polaron tunneling (NSPT) is the appropriate conduction mechanism model.

cours et TP Physique 1

Effectuer la mesure de courant, de tension et de résistance à laide d’un multimètre. Calculer la résistance à l’aide de la loi d’Ohm Assembler le montage de circuits électriques simples et mixtes. Déterminer la résistance équivalente d’un circuit mixte. Vérifier la loi des nœuds et la loi des mailles Mettre en évidence l’utilité et l’utilisation du pont de Wheatstone te savoir des métaux à partir la mesure de la résistivité.

Les objectifs TP S1 et S2 de physique science technologie.

Minimisation des erreurs au maximum pour rapprocher a des grandeurs real.

Utilisations des instruments de calcules de différents phénomènes physiques, (chute libre, choc élastique et inélastique, loi de Newton, pendule de torsion…).

Interprétation des résultats.

The TP S1 and S2 objectives of physics science technology.

Minimization of errors to the maximum to approximate to real quantities.

Uses of instruments for calculating different physical phenomena (free fall, elastic and inelastic shock, Newton's law, torsion pendulum, etc.).

Results interpretation.

The thermal projection technique is a method of surface cover permitting to get deposits while putting in œuvre a large specter of processes (projection to the flame, to the torchlight to plasma of bow soufflé, etc.) and of materials (metallic, ceramic alloys, polymers and composite materials, etc.). It permits to achieve coatings of several score micrometers to some millimeters. This process consists in heating and to melt the material to put down, presented under the shape of gunpowder or a thread, thanks to a source to high energy (electric or combustion). The melted particle transfer or semi - fondues take place with the help of a gas, the most often hot. The melted gunpowder and accelerated comes to collapse then then to solidify on the surface of the substratum

The flashover of pollution, observed on the insulators used in high voltage transmission, is one of the most important power transmission stakes. It is a very complex problem due to several factors including the modelling difficulties of complex shapes of insulators, different pollution densities at different regions, non-homogeneous pollution distribution on the insulator surface and unknown effect of humidity on the pollution. In the literature, some static and dynamic models have been developed by making some assumptions and omissions to predict the flashover voltages of polluted insulators. This paper aims to experimentally analyse the flashover process and simulation of the distributions of the potential and the electric field under 50 Hz applied voltage on a real model simulating the 175CTV outdoor insulators largely used by the Algerian Company of Electricity and Gas (SONELGAZ). This real model is studied under non-polluted (distilled water), and polluted (distilled water and sand) environments. The simulations were carried out by using the COMSOL multiphysics software. This program uses the finite element method to solve the partial differential equations that describe the field. Experimental results made in the laboratory and simulation results are original and found to be congruent.

This paper investigates the unsteady state of the heat ventilation in a box prototype with two holes. The CFD simulations were conducted using ANSYS Fluent 17.0 software, which solves the Navier-Stokes equations in conjunction with the standard k-ω turbulence model and by a finite volume discretization method. The presented results, consisting of the distribution of the velocity fields, the temperature, the total pressure and the turbulent characteristics, are very useful to determine the time required for the heating operation and to shrink the energy consumption of the buildings. The comparison between the founded results affirms that the heating time presents a straight effect on the velocity fields. However, for the temperature, the box prototype requires more time and more energy to warm up. In our application, we confirm that the duration of 30 s is sufficient to allow the heating of the box prototype. Indeed, the numerical results compared using the experimental data developed in our laboratory confirms the validity of the numerical method. The good agreements validate the considered computational method.

An ab initio study was performed using the full-potential linearized augmented plane wave method (FP-LAPW) within the framework of density functional theory (DFT), with both approximations: generalised gradient approximation GGA for the structural proprieties calculation and electronic properties we have used both approximations GGA (Generalized Gradient Approximation) and LDA (local Density Approximation) to improve the results of the compound Heusler LaPtBi which have an technological interest in the spintronic field. The calculation has showed that LaPtBi compound have a half metal ferromagnetic characterisation with a band gap in one direction of spin. The results in this work are predictive values because of the absence of available data.

The mechanical discrete or continuum structures are actually of great importance in the application field of contemporary modern industry. However, during their life time these structures are often subjected to considerable external stresses or to high amplitudes of vibrations which can cause them largedeformations and internal stresses which can cause them internal cracking or even their total destruction. In order to avoid these types of problems, the concept of static and dynamic analysis of these structures is recommended, and due to the complexity of their shape and size, the finite element method is the most used. The latter is currently recognized as a very powerful technique for the static and dynamic analysis of discrete or continuous structures of complicated form applied in the field of mechanics, aeronautics, civil engineering, maritime or robotics. Consequently, the calculation and dimensioning of these mechanical systems by the finite element method plays an important role at the service of the industry for possible sizing and prediction of their lifetime. Our work consists of static and dynamic analysis of two-dimensional discrete and continuous mechanical systems using the finite element method based on the main elements of bars, beams and plates, under the effect of external excitations with different boundary conditions. The discrete structures considered are two-dimensional in metallic framework interconnected to the nodes by welding, riveting or bolted under various boundary conditions. Their elements are modeled comparatively by bar elements and beam elements, while for continuous structures the elements are rectangular thin plates with different boundary conditions. The excitation forces are based on periodic, random or impulsive forces and a numerical solution by development of a program to describe the behavior of these structures is realized. The mass and stiffness matrices of all the structures are determined respectively by assembling the bars, beam and plate elements based on the kinetic and deformation energy for each element. Thedisplacements, the node reactions and the axial forces in all the elements as well as the transverse stresses and the eigenvalues of the structures under different boundary conditions were also calculated and good results were obtained compared to those obtained using other software already existing. In fact, analysis using the finite element method will allow the proper dimensioning and design of complex industrial mechanical structures according to different boundary conditions, their internal loading and their vibratory level.

The use of efficient systems in order to reduce the energy consumption presents in nowadays a great challenge. Indeed, the use of the renewable energy in the heat ventilation of building application becomes very crucial. In this work, we are interested on the study of the turbulent flow in a box prototype. In this prototype, a solar system is integrated to supply the hole inlet with a hot air. The numerical model is based on the resolution of the Navier-Stokes equations in conjunction with the standard k-ω turbulence model. These equations were solved by a finite volume discretization method using the commercial CFD code ANSYS Fluent 17.0. To accurate the numerical results, the meshing effect on the numerical results was studied to choose the optimal mesh with a minimum calculated time. The numerical results were compared using anterior results developed in our laboratory. The good agreements confirm the validity of the numerical method.