JFAS_Vol 05 N 01
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Item Monitoring And Thermal Analysis Of Co-composting Process In A Forest Nursery Modern (tunisia)(University of Eloued جامعة الوادي, 2013-01-01) M’sadak, Y.; Saad, I.; Saidi, D.The objective of this work was to study thermogenesis during the process of Co-composting to assess the possibilities of thermal destruction of the germination capacity of weeds seeds. A regular monitoring of temperature has been achieved, using a probe thermometer, at nine locations of heap crafted. The outlines of temperature profiles allowed the identification of the four phases of the process, from a temperature monitoring, which is taken twice a day. The mid-monthly monitoring of temperatureshowed no significant differences for the first three dates of monitoring, whatever the depth and whatever time study. The bi-monthly monitoring showed insignificant differences for the first three dates, whatever the depth of the heap and whatever the studied time. The last three dates showed insignificant differences for the time of recording, whereas for the depth, the results obtained were significant.Item Study Of Fluoride Glasses Devitrification-based Magnesium(University of Eloued جامعة الوادي, 2013-01-01) Benhamideche, C.; Boutarfaia, A.; Poulain, M.The kinetics of devitrification of fluoride glasses stabilized by magnesium fluoride when heated for some time between the glass transition and melting temperatures. The crystallization kinetics of AlF3-YF3-PbF2-CdF2-MgF2 glass prepared by melting the halide powders were studied by differential scanning calorimetry (DSC). The heating rate varied between 2 and 10 Kmim-1. Arami’s exponent (n) obtained by a non-isothermal method was 1.5 and 2.5 for a AlF3-YF3-PbF2-CdF2-xMgF2 (x= 0, 5, 10) and n > 2.5 for a AlF3-YF3-PbF2-CdF2-15MgF2. According to the classical interpretation of n, these magnitudes correspond to diffusion controlled growth of crystals. The activation energies for crystallization, (E), varied from 195-326 KJ/mol. These results confirm the improved stability of these glasses, which could be used as base glasses for low phonon energy fluoride glass fibers.Item Effect For A Single Roughness E=5,63mm Of Experimental To Study Hydraulic Jump Profile In A Channel In U A Rough Bottom(University of Eloued جامعة الوادي, 2013-01-01) Ghomri, A.; Riguet, F.; Debabeche, M.This study aims to study the hydraulic jump controlled by threshold, moving in a channel profile 'U' bottomed rough for a single roughness E=5,63mm. Functional relations in dimensionless terms, linking the different characteristics of the projection, showing the effect of roughness of the bottom of the channel are obtained. The hydraulic jump is the primary means used by hydraulic structures to dissipate energy. This hydraulic jump is formed at the sharp transition from a supercritical flow a stream flow.Item Behavior Of Acacia Plants Installed On Substrates Based On Compost Sylvicole With Or Without Methacompost Of Poultry In A Modern Nursery In Tunisia(University of Eloued جامعة الوادي, 2013-01-01) M’sadak, Y.; Ben M’barek, A.; Tayachi, L.The present study aims principally the evaluation of germination and of plant growth of Acacia cyanophylla installed, on the one hand, on the gross forestry compost (CSB) in its purest form, produced in a forest nursery in Tunisia, on the other hand, on the CSB mixed with poultry methacompost (MCA) refined (solid residue from the industrial digester) in its two states, namely the output of the decanter (MCAA) and the outlet of the digester (MCAA') according to the same ratio, of 20 %. Both tested mixtures were the best, due to the direct assessment of physico-chemical properties of various mixtures made. The incorporation of the MCA with the CSB has a notable positive effect on germination, and consequently on the growth of Acacia seedlings in terms of height and diameter. The CSB presented an intermediary vegetative behavior.Item Detection Of Static Eccentricity Fault In Saturated Induction Motors By Air-gap Magnetic Flux Signature Analysis Using Finite Element Method(University of Eloued جامعة الوادي, 2013-01-01) Halem, N.; Zouzou, S. E.; Srairi, K.; Guedidi, S.; Abood, F. A.Unfortunately, motor current signature analysis (MCSA) cannot detect the small degrees of the purely static eccentricity (SE) defects, while the air-gap magnetic flux signature analysis (FSA) is applied successfully. The simulation results are obtained by using time stepping finite elements (TSFE) method. In order to show the impact of magnetic saturation upon the diagnosis of SE fault, the analysis is carried out for saturated induction motors. The index signatures of static eccentricity fault around fundamental and PSHs are detected successfully for saturated motor.Item Ecodesign Criteria For Composite Materials And Products(University of Eloued جامعة الوادي, 2013-01-01) Attaf, B.According to sustainable development principles, the design of a composite product must be in compliance with the new regulations and standards in terms of Health protection (H) and Environmental preservation (E) besides Quality assurance (Q). With this argument as an objective, our contribution aims to innovate and develop new methodologies providing sustainable design of new generation of composite products through the consideration of the three balanced key aspects: H, E and Q. To achieve these requirements, we have defined and developed new criteria in the form of eco-coefficients, which can later on be implemented into mechanical characterization tests, in advanced composite formulations and associated constitutive equations. They can also be integrated into future finite-element computer programs to assess and improve the performance of the H-E-Q interrelated function.Item Analysis And Optimizationofin1-xgaxasysb1-ythermophotovoltaiccellsunderlowradiatortemperatures(University of Eloued جامعة الوادي, 2012-07-01) Bouzid, F.; Maamri, N.In this paper,we investigated the heat to electricity conversion efficiency of In1-xGaxAsySb1-yradioisotope thermophotovoltaic (RTPV) converter with x=0.8 and y=0.18, taking account of the photons with energy below the cells bandgap using a comprehensive analytical process. This was done with a computer program designed for this reason, which allowed the computation of the cell performance under a variety of specified incident radiation spectra as well as a variety of material parameters. The results show that for an emissivity value of 0.78, a cell thickness of about 7µm with low front recombination velocity(700cm/s),a conversion efficiency greater than 29% can be obtained for radiator’s temperature of1300°k at ambient temperature. This efficiency will decrease as the cell temperature increase.Item Thermodynamic Modelling Of A Pistons Engine: Calculation Of The Nox Emissions(University of Eloued جامعة الوادي, 2012-07-01) Mahfoudi, N.; Kadja, M.The internal combustion engines are under development remarkable these last decades, but they represent, currently, a very important source of polluting gas emissions. The nitrogen oxides (NOx) form part of these polluting emissions, and have a harmful effect on human health, as well as the environment. Considering the complexity of the process of formation of the latter, many numerical simulations were developed, our work, allows the calculation of the nitrogen oxide rate (NO) in exhaust gases, starting from the developed equations of the chemical kinetics, while being based on the thermal mechanism of Zeldovich. Simulation is carried out for a gasoline engine, and the results obtained show that: the maximum of NO concentrations corresponds to an equivalent ratio of 0,9. For leaner or richer equivalence ratios, concentration decreased. The NO concentrations depend of various parameters (spark timing angle, combustion duration, and engine speed).Item Influence Of Broken Rotor Bars Location In The Squirrel Cage Induction Motor Using Finite Element Method(University of Eloued جامعة الوادي, 2012-07-01) Halem, N.; Zouzou, S. E.; Srairi, K.; Guedidi, S.It is well known that the number of broken bars and varying load affect on the amplitudes of specific harmonic components in the process analysis of induction motors under broken rotor bars. The location of broken bars is an important factor which affects the diagnosis of the broken bars defect. In this paper the simulation is determinate for different cases for distribution of broken bars under induction motor pole in order to show the impact of broken bars location upon the amplitude of harmonic fault. The simulation results are obtained by using time stepping finite elements (TSFE) method. The geometrical characteristics of motor, the effects of slotting and the magnetic saturation of lamination core are included in induction motor model.Item Extraction And Antioxidant Activities Of Two Species Origanum Plant Containing Phenolic And Flavonoid Compounds(University of Eloued جامعة الوادي, 2012-07-01) Benchikha, N.; Menaceur, M.; Barhi, Z.The antioxidant of ethanolic extract of two species of Origanum and essential oil of plant Origanum vulgare were investigated and also the total phenolic and flavonoid content measured. The radical scavenging activity was measured using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Total phenolic and flavonoid contents were estimated by Folin-Ciocalteu and aluminum chloride methods, respectively. According to the results the leaves extracts have very important values for polyphenols (266.86 mg GAE / g and 194.78 mg GAE / g) and high antioxidant activity; DPPH (IC50 = 1.37 g / l and IC50 = 1.53mg / l ) for species majorana, and vulgare respectively; also the DPPH of essential oil of Origanum vulgare was IC50 = 15.360 mg/l . This data suggest of these extracts as a natural source of phenolic compounds and antioxidant.