The study of propagation characteristics is a fundamental step in mobile radio engineering; which is intended to achieve maximum performance for a mobile radio system. To do this, the propagation models are essential tools for this study such as the evaluation of the signal strength received by a mobile terminal, the evaluation of coverage radii and deduce the number of cells needed to cover a given area, such as radio planning, which in turn is the step that aims to estimate the necessary equipment and configurations of the radio interface. In this work we adopt the standard K factor model and OKUMURA HATA model to demonstrate a propagation model adapted to the physical environment of the city of Annaba in Algeria using a linear regression algorithm based on the ordinary least squares method. Radio measurements were carried out on the CDMA network of operator Mobilis. The calculation of the square root of the mean square error between the actual data and the radio measurements and the prediction data derived from the model implemented allowing the validation of the results obtained. A comparative study between the value of the RMSE obtained by the new model and those obtained by the models K standard factors and the model of OKUMURA HATA allows us to conclude that the new model is better adapted to our local environment than that of OKUMURA HATA. The new model obtained can help increase the performance of mobile radio systems deployed in our territory. © 2017, School of Electrical Engineering and Informatics. All rights reserved.

A three-dimensional time-dependent numerical study of the flow instabilities in a simulated Czochralski system is conducted. The comparison with previously published experimental results is reported. The simulations were performed using a refined grid in order to investigate flow instabilities in the crucible. Simulations have been carried out for various crystal rotational speeds, by taking into account the effects of Rayleigh and Marangoni numbers. The temperature fluctuations near the crystal/liquid interface are analyzed. The method used for that purpose is the Fast Fourier Transform with the corresponding spectra. From numerical simulations, it has been observed that for rotational speeds of the crystal less than 10 rpm, the temperature fluctuations are increased until a magnitude of 1.1 K over a period of 6 min. For crystal speeds larger than 10 rpm the fluctuations are extremely reduced to a magnitude less than 0.02 K.

Ensuring (QoS) in wireless sensor networks (WSNs) is a challenging issue due to the lack of resources and energy exhausting of sensor nodes. In this paper we propose a new QoS aware routing protocol for multi-hop wireless sensor networks based on cross-layer interaction between the network, MAC and physical layers. At physical layer, a link quality estimator is studied for the purpose of evaluating link quality. At MAC layer, a differentiated services mechanism is used to distinguish between real time and non-real time packets and to allocate more channel resources for real time traffic; TDMA slots also have been modified to allocate more and earlier slots to real time packets. At network layer, a routing path selection algorithm is introduced for QoS optimisation. Simulation results show that our proposed protocol improves network’s performances in terms of energy efficiency and QoS.

Copper destined for electrical cabling require a compromise of mechanical properties and electrical resistivity. The drawing process accompanied by the formation of crystalline defects, such as gaps and dislocations, which leads to the increase in hardness, and therefore to the increase in resistivity, a very important characteristic for the conductivity and the efficiency of the cable. The scope of this work is to investigate the phenomenon of deformation texture evolution while copper wire drawn destined for electric cable-making and to understand its relationship with the electrical conductivity. In this study, we notice that the hardness and the resistivity increase with an increase of the deformation level. On the other hand, a slight decrease in the resistivity of the wires was observed after a holding time of 30 min at 260°C. The annealing of wires at 260°C for 9 min of holding time leads to a recrystallisation especially for high deformations and a gradual return of the mechanical properties and of the microstructure towards a state close to the state of the wire rod with the extension of time . The recrystallization texture is composed of the same components as the drawing texture, fibers <111>//ND (Normal Direction) and <001>//ND. The decrease in the intensity of the fiber after annealing is observed. On the other hand, the fiber <001> // ND remains stable.

The performance of photovoltaic (PV) module is affected by outdoor conditions. Outdoor testing consists installing a module, and collecting electrical performance data and climatic data over a certain period of time. It can also include the study of long-term performance under real work conditions. Tests are operated in URAER located in desert region of Ghardaïa (Algeria) characterized by high irradiation and temperature levels. The degradation of PV module with temperature and time exposure to sunlight contributes significantly to the final output from the module, as the output reduces each year. This paper presents a comparative study of different methods to evaluate the degradation of PV module after a long term exposure of more than 12 years in desert region and calculates uncertainties in measuring. Firstly, this evaluation uses three methods: Visual inspection, data given by Solmetric PVA-600 Analyzer translated at Standard Test Condition (STC) and based on the investigation results of the translation equations as ICE 60891. Secondly, the degradation rates calculated for all methods. Finally, a comparison between a degradation rates given by Solmetric PVA-600 analyzer, calculated by simulation model and calculated by two methods (ICE 60891 procedures 1, 2). We achieved a detailed uncertainty study in order to improve the procedure and measurement instrument.

Three main contributions are presented in this paper. First, the septic quasi-interpolants are calculated with all their coefficients. Second, we explore the results to solve a generalized and broad class of Fredholm integral equations of the second kind. Finally, we present three degenerate kernel methods; the latter is a combination of the two previously established methods in the literature. Moreover, we provide a convergence analysis and we give new error bounds. Finally, we exhibit some numerical examples and compare them with previous results in the literature.