Publications Internationales
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Item Life cycle assessment application for the medical waste management in Algeria(2019) Kihal, Nafika; Tairi, AbdelazizOur study aimed to assess environmental im-pacts of a medical waste (MW) management sys-tem in using life cycle assessment (LCA) methodol-ogy in Algeria. We use standardized CML2 method to ana-lyze the environmental impacts resulting from one scenario’s MW management system for One kilo-gram of MIW disposed, including: production raw material of the MW, transportation, MW incinera-tion and MW ash storage. Seven impacts categories were taken into ac-count: Abiotic depletion (AD), Acidification, Eu-trophication, Global warming (GWP100), Ozone layer depletion (ODP), Human toxicity (HT) and Fresh water aquatic ecotoxicity (FAET). The data was obtained from Bachir Montouri hospital, the ECFERAL company, ecoinvent data-base and the literatures. Our study showed that all impact categories had significant values, except for ODP. The MW-Transportation contributed to the majority of im-pacts category. The highest impact category of the MW process was the eutrophication about 51% resultant of the fiber cotton production (38%). Despite significant emissions of dioxins, the BTEX and heavy metals which contributed for both HT and FAET impact, the MW incineration process contributed the least for AD, acidification, eutroph-ication, GWP100 after the MW ash storage. Our findings provide a useful tool to guide pol-icymakers in their choice of environmental perfor-mance indicators for disposal of MW.Item Determination of university students’ misconceptions about light using concept maps(Elsevier, 2014) Blizak, Meriem Djanette; Chafiqi, FouadThe concept map has evolved, in recent years, as an important teaching and learning tool. It engages students in active learning and assists instructors with their delivery. Thus, we believe that it has the power to be relevant and effective to reflect the design of a poly-functional teaching tool. We argue in favor of renewing didactic tools used in education, in general, and in teaching GO (geometric optics) in particular. The main purpose of this study, however, is to show that the concept mapping is a very effective way in terms of revealing the misconceptions of students, studying GO, during their university year. 52 freshman students (first year) majoring in life science and nature (LSN) were asked to draw a conceptual map about propagation of light; a two-stage experiment: before and after formal teaching sessions. The findings of the qualitative analysis of the students’ maps are in line with the results of other research; students have many misconceptions about light and traditional strategy used for teaching GO is not effective for conceptual change. Also, The approach of scoring tasks, as only one survey is not recommendedItem Knock characterization and development of a new knock indicator for dual-fuel engines(Elsevier, 2017) Lounici, Mohand Said; Benbellil, Messaoud Abdelalli; Loubar, K.; Niculescu, D.C.; Tazerout, MohandDual-fuel mode is a promising technique for natural gas utilization in internal combustion engines. However, for high loads operation, the engine risks to go through a hazardous knocking regime. Knock phenomenon is an abnormal combustion that can cause some disagreeable effects in engines where it occurs. It can even induce brutal irreparable engine damage under severe knocking conditions. The present paper aims first to highlight and characterize knock in dual-fuel engines fueled with natural gas as main fuel and diesel as pilot fuel. Description of this phenomenon is investigated in this type of engines. Knock behavior in dual-fuel engine is compared to spark ignition engine case. Cyclical variability of this phenomenon is studied. A new knock indicator, based on in-cylinder pressure analysis, is proposed in order to identify and evaluate knock in dual-fuel engines. In addition, knock effects on heat release, cylinder wall temperature and engine performance and emissions are examined. New techniques to delay knock appearance in this type of engines are investigated. It is found that the increase in pilot fuel quantity is an effective technique to delay knock onset in NG dual-fuel enginesItem Oxygen diffusion and migration in clean and defective uranium nitride UN (0 0 1) surfaces(Elsevier, 2018) Zergoug, T.; Abaidia, Seddik-El-Hak; Nedjar, A.This study focuses on the diffusion of atomic and molecular oxygen through the uranium mono-nitride UN (0 0 1) surface. The adsorption of oxygen at the most favorable sites has been checked on different surface states namely: clean surface and surfaces containing defects such as inclusion atoms. Inclusions atoms are positioned at a uranium U atom vacancy or at a nitrogen N atom vacancy location of the UN (0 0 1) surface. Neptunium, plutonium, protactinium, silver and neodymium which are the most probable nuclear reactions (n, U) products have been selected as U atom substitute. Some light elements such as carbon, chromium and silicon were used to replace an N atom. The first principle calculation, based on Density Functional Theory (DFT) was used, taking into account the Generalized Gradient Approximation (GGA) and the Projector-Augmented Wave (PAW) to describe the exchange-correlation functional. The purpose of this work is to verify the oxygen adsorption energy variations performed across all the studied surfaces. The most favorable sites of UN (0 0 1) clean and defective surfaces to oxygen O atom diffusion were preliminary identified. In the second step, atomic dynamical Potential Energy Surface (PES) was used to study the interaction between O atom and UN (0 0 1) surfaces at these sites. Finally, Nudged Elastic Band (NEB) method was used in order to investigate the migration of O atom through the UN (0 0 1) surfaces. The results show that at the bridge site, the adsorption and incorporation energies of oxygen atom on and in the UN (0 0 1) surfaces respectively, do not substantially vary with the type and position of the studied impurities. But, at the N vacancy site, the adsorption energy of the O atom decreases practically when UN (0 0 1) surfaces contain inclusion atoms compared to the clean surface case. Furthermore, the NEB calculations show discrepancies for the Minimum Energy Path (MEP) during the migration of the O atom at the bridge site through the studied UN (0 0 1) surfaces and depending on the type and position of the added impurities. Among the studied MEPs, protactinium is found to be the most suitable barrier to the diffusion of oxygen through the UN surface as an inclusion on UN (0 0 1)Item Measurements and identification of smart magnetomechanical elastomer composite materials properties in shear mode(Institute of Physics Publishing, 2019) Nedjar, Ali; Aguib, Salah; Djedid, Toufik; Nour, Abdelkader; Meloussi, MounirMagnetorheological elastomer composite materials (MRE) are a new class of intelligent active materials composed of ferromagnetic particles, of micrometric size, dispersed in a silicone elastomer matrix, which exhibit variable stiffness and damping properties which are modifiable under the application of an external magnetic field. Currently, these devices are primarily used in automotive and building applications, but they can easily be adapted to meet the requirements of aerospace applications. The development process and experimental characterization needed to evaluate the active control performance of this material have been made. This is done by characterizing the mechanical properties as a function of the magnetic field, as a function of the excitation frequency and as a function of the different percentage of ferromagnetic particles loading. An example of application of this material in aeronautics is also presentedItem Bias voltage effect on magnetron sputtered titanium aluminum nitride TiAlN thin films properties(EDP Sciences, 2019) Ait-Djafer, Amina Zouina; Saoula, Nadia; Wamwangi, Daniel; Madaoui, Noureddine; Aknouche, HamidIn this study, a negative substrate bias voltage is used to tune the structural, morphological, mechanical and electrochemical properties of TiAlN coatings fundamental for protective coating applications. TiAlN thin films have been deposited on glass, (001)Si and stainless steel substrates by RF magnetron sputtering at a power density of 4.41 W/cm2. The deposition rate was determined from X-ray reflectivity measurements to 7.00 ± 0.05 nm/min. TiAlN films used in this work were deposited for 60 min to yield a film thickness of 420 nm. Structural analysis has shown that TiAlN coating forms a cubic (fcc) phase with orientations in (111), (200), (220) and (222) planes. The deposited coatings present maximum hardness (H = 37.9 GPa) at −75 V. The dependence of hardness and Young's modulus and corrosion resistance on microstructure has been established. Electrochemical studies by potentiodynamic polarization in aggressive environment (3.5 wt.% NaCl) have revealed that stainless steel substrate with TiAlN coating exhibits excellent corrosion resistanceItem A multi-objective approach to weather radar network architecture(Springer, 2019) Boudjemaa, Redouane; Oliva, DiegoThis paper proposes a multi-objective optimization approach for the optimal placement of a weather radar network. Assuming a finite geographical region and a limited number of weather radars, a network is produced by considering the minimization of the total partial beam blocking percentage of the network and the minimization of network installation and maintenance costs. Several constraints on the solutions are considered such as terrain topography, radar beam elevation, distance between radars and distance from the power grid and roads. In order to reduce the number of possible combinations of radar networks, the solution space is discretized into a gridded system. The multi-objective optimization problem is solved by four different evolutionary algorithms, and the obtained results are used in a land clutter simulation of the whole network. The presented approach can serve as an analysis tool for a decision support system by providing meteorologist a set of Pareto optimal solutions to facilitate the selection of future prime sites for the installation of weather radarsItem Synergistic effect of Rutile-Anatase Fe-doped TiO2 as efficient nanocatalyst for the degradation of azucryl red(IOP Publishing, 2019) Kerrami, Ahmed; Mahtout, Laila; Bensouici, F.; Bououdina, M.; Rabhi, S.; Sakher, E.; Belkacemi, H.The aim of this work is to reduce the impact on the environment of a basic textile dye (azucryl red) using a semiconductor TiO2 and Fe doped TiO2 powders calcined at 600 °C as catalysts. The refinements based on the Rietveld method of x-ray diffraction patterns indicate the formation of Rutile phase for un-doped TiO2, while a phase transformation into Anatase phase occurs upon Fe doping. Scanning electron microscopy analysis reveals the formation of spherical-like particles at the nanoscale that agglomerate into aggregates, meanwhile the chemical composition checked by EDX spectroscopy is close to the stoichiometry. FTIR analysis reveals the presence of OH groups that favor the photocatalytic reaction, while EPR analysis confirms the existence of Fe3+ resulting in the creation of oxygen vacancies. Excellent photocatalytic degradation of azucryl red is obtained by 0.2% Fe doped TiO2, the removal of 100% of dye is achieved within a very short time of 10 minItem New gear fault diagnosis method based on MODWPT and neural network for feature extraction and classification(ASTM International, 2019) Afia, Adel; Rahmoune, Chemseddine; Benazzouz, Djamel; Merainani, Boualem; Fedala, SemchedineGear fault diagnosis using vibration signals has become the subject of intensive studies to detect any sudden failure. However, these signals exhibit nonlinear and nonstationary behaviors when the rotating machine operates under multiple working conditions. Furthermore, fault features extraction and classification of multiple gear states are always unsatisfactory and considered as a huge task. This is the main reason that motivates us to develop a new intelligent gear fault diagnosis method in order to automatically identify and classify several kinds of gear defects under different work conditions. So in this article, we propose a combination between the maximal overlap discrete wavelet packet transform (MODWPT), entropy indicator, and a multilayer perceptron (MLP) neural network as a new automatic fault diagnosis approach. MODWPT decomposes the data signal into several components using a uniform frequency bandwidth. Each decomposed component is selected to extract feature vector using entropy indicator. Finally, MLP provides a powerful automatic tool for identifying and classifying the aforementioned extracted features. Experimental vibration signals of healthy gear; gear with general surface wear; gear with chipped tooth in length; gear with chipped tooth in width; gear with missing tooth; and gear with tooth root crack are recorded under fifteen different work conditions to test the effectiveness of the suggested technique. Experimental results affirm that our proposed approach can successfully detect, identify, and classify the gear fault pattern in all cases