Guelma, Algeria
Guelma, Algeria

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Remadnia M.,University of 08 May 1945 | Nemamcha M.,University of 08 May 1945 | Herous L.,University of 08 May 1945 | Dascalescu L.,University of Poitiers
IEEE Transactions on Dielectrics and Electrical Insulation | Year: 2011

The aim of the present paper is to evaluate the factors that affect the discharge of mmsized High-Impact Polystyrene (HIPS) granules forming uniform layers at the surface of grounded plate electrodes. The samples were charged using a triode-type electrode arrangement, consisting in: (i) a metallic plate connected to the ground; (ii) a wire-type corona electrode parallel to the grounded plate and energized from an adjustable dc power supply; (iii) a metallic grid of well-defined potential. The decay of the potential at the surface of the samples was measured with the capacitive probe of an electrostatic voltmeter (TREK, model 370). The experimental design methodology was employed for quantifying the effects of three variables that influence the process of potential decay at the surface of a corona-charged layer of insulating granules: (i) the initial potential, imposed by that of the grid electrode (range ±1000 to ±2800 V); (ii) the granule size (range 0.3 to 1.5 mm); (iii) the number of compact granular layers (1 to 3 layers). It was found that the surface potential decay is accelerated by the grid potential, but is slower for coarser, multi-layered granular samples. These results are useful for the design of the electrostatic separation processes involving this class of insulating materials. © 2011 IEEE.


Kachi M.,University of 08 May 1945 | Kachi M.,University of Poitiers | Nemamcha M.,University of 08 May 1945 | Lazhar H.,University of 08 May 1945 | Dascalescu L.,University of Poitiers
Journal of Electrostatics | Year: 2011

The control of the residual electric charge carried by granular materials processed in various electrostatic installations is a prerequisite for the safe and efficient operation of the respective industrial equipment. The aim of the present work was to evaluate the neutralization efficiency of polyethylene granules exposed to an AC corona discharge from a wire-type electrode. The control variables and their domains of variations were the following: the amplitude and the frequency of the applied high voltage (16-18 kV, 20-400 Hz), the position of the corona electrode (3-7 cm above the ground plate that carries the sample) and the duration of the exposure to the corona discharge (4-10 s). The surface potential decay method was used for monitoring the charge carried by granular samples of PE before and after neutralization. Design of experiment methodology was employed to evaluate the influence of each of the above mentioned control variables and determine the optimum operation conditions. The efficiency of the neutralization was characterized by the ratio between the values of the surface potential before and after AC corona discharge exposure. The obtained results show that neutralization efficiency may be improved by increasing the frequency of the high voltage as well as by adequately correlating its amplitude with the inter-electrode spacing. © 2011 Elsevier B.V.


Mahdjoub H.,Annaba University | Khelifa R.,Mouloud Mammeri University | Zebsa R.,science and Earth and Universe science Faculty | Mellal M.K.,Annaba University | And 2 more authors.
International Journal of Odonatology | Year: 2014

Coenagrion mercuriale is a threatened damselfly in most parts of its geographic distribution. It is listed as endangered in North Africa, where no data on its biology or ecology are available. This study aims to illustrate the reproductive behaviour and habitat preferences of adults in a population located in north-east Algeria, representing the southern limit of the species distribution. After emergence, adults spent 3 to 4 days away from the water to mature. Young mature individuals returned to the stream to mate, sometimes not far from their emergence site. The mean duration of copulation and oviposition were 20.08 ± 8.79 min (± SD) and 52.66 ± 12.17 min (± SD), respectively, separated by a short post-copulatory rest of 4.60 ± 2.02 min (± SD). Copulation duration was positively correlated with male body length while resting duration was positively related to copulation duration. Single males and breeding pairs preferred the same habitats, characterized by relatively dense and high in-channel bank vegetation, and a quite large stream bed, with a substrate which mainly consisted of clay and silt. A comparison of the reproductive behaviour and habitat preferences with a population located in the northern limit of the distribution range is presented and discussed. © 2014, © 2014 Worldwide Dragonfly Association.


Khelifa R.,Mouloud Mammeri University | Guebailia A.,Jijel University | Mahdjoub H.,Annaba University | Aouaouche M.S.,Mouloud Mammeri University | Houhamdi M.,University of 08 May 1945
International Journal of Odonatology | Year: 2015

The determination of seasonal regulation is important to understand how species have adapted to their local environmental conditions. In this study, we investigate the life history of a North African endemic damselfly, Platycnemis subdilatata, in a northeast Algerian population. We combined field and laboratory investigations to assess the embryonic development, larval growth, emergence pattern and adult flight season. The embryonic development was direct and asynchronous, with 50% of all eggs hatching after three weeks of egg laying and a hatching period ranging from 13 to 51 days. Hatching success was 48.8%, and the causes of hatching failure were infertility and unhatchability. Larval population structure was quite asynchronous during the winter and less so before emergence. The occurrence of larval diapause is improbable due to the increase of the proportion of the last larval stadium in late winter. Emergence was asynchronous with half of the larval population (EM50) emerging after 44 days within an emergence season of 122 days. Sex ratio at emergence was slightly female biased (50.6%). The flight season lasted 133 days starting from early May. The species reached its sexual maturity after six and seven days of emergence in male and female, respectively. Lifespan was not significantly different between sexes with a mean of 7.75 ± 6.45 days (± SD). Our results suggest that the species is univoltine with a typical summer species life history. © 2016 Taylor & Francis.


Ziou H.,University Mohamed Khider of Biskra | Guenfoud H.,University of 08 May 1945 | Guenfoud M.,University of 08 May 1945
International Journal of Structural Engineering | Year: 2016

Functionally graded material (FGM) beams possess a smooth variation of material properties due to continuous change in micro structural details. The variation of material properties is along the beam thickness and assumed to follow the power-law. An exact element based on the first order shear deformation theory was developed. The finite element method is used here to study extensively the static analysis. A cantilever beam subjected to a concentrated force P at the free end for different length-to-thickness ratio has been chosen here for the analysis. For each example, Poisson's ratio of the P-FGM beam is assumed to be varied continuously throughout the thickness direction according to the power law, and other time it is held constant. Timoshenko beam theory is used to capture the shear deformation. The governing equations and boundary conditions are derived from virtual work principle. In this study, the influences of the volume fraction index, length-to-thickness ratio and the Poisson's ratio on the mid plane deflections, stresses distribution and strain energy along the thickness of FGM beam are examined. Copyright © 2016 Inderscience Enterprises Ltd.

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