Liste des communications
Fusion and heat affected zones damage during fatigue assessment assisted by digital image correlation
This work aims at following strain field expansion incurred in welded austenitic stainless steel during cyclic loading assisted by three dimensional Digital Image Correlation (3D DIC) method. The latter is an indicative device helping to distinguish the high stressed area from the low stressed one during fatigue test. 3D DIC monitoring of strain field and stress condensation in the studied area reveals the presence of simultaneous strain localization in two regions bordering between them an area with a reduced stress level. SEM-ECCI analysis of the hybrid zone supposes that the microstructural damage in the welded joint would be controlled by hardening and softening phenomena, caused by sub-grains formation and twins annihilation during loading Voir les détails
Mots clés : Cracks, Image processing, Strain mapping, Welded joint
Prediction of Lifetime System Electric Performances Based on Battery Corrosion Effects Included in a Stand Alone Hybrid System- a Case Stud
The ideal system type of this paper work demonstrates that wind power does make sense in situations with high wind speeds and high gasoline prices. The suggested hybrid power system prevented 16.26 t/y of CO2 gas from being added to the village's local environment and saved 6176.15 liters of fossil fuel per year. Aluminum is prone to pitting corrosion and copper to environmentally aided cracking, which are the two main current-collector materials used in lithium-ion batteries. In the other hand. The corrosion process that happens at the interface between the active material and grid material of the positive plate of the lead-acid battery storage is discussed in this paper's technical performance implications. The system is modelled for each time step for each year of the project's 20-year lifespan. In order to discover the ideal system architecture, we first ran the model without Multi-Year and utilized the Optimizer. This study's objective is to carry out technical and financial optimization throughout the energy system's lifespan while taking into consideration the mixed storage system's corrosion-related deterioration as a key parameter. The best cost study for the HRES is completed with the assistance of the HOMER Pro MATLAB Link. Voir les détails
Mots clés : Battery, corrosion, Multi-year planning, planning optimization
Multiyear Load Growth Based TechnoFinancial Li-ion Discharge and Corrosion Behaviors in a Microgrid Located in Algeria
The primary current-collector materials used in lithium-ion cells, aluminum and copper, are both susceptible to environmental degradation. Localized corrosion occurred on bare aluminum electrodes during simulated ambient-temperature cycling in an excess of electrolyte. The highly oxidizing potential associated with the positive electrode charge condition was the most important factor. In contrast to typical aqueous electrolyte pitting, each site was filled with a mixed metal/metal-oxide product, forming surface mounds or nodules. The status quo for relaying such confidence is economic and technical planning models, which are used to design microgrids and distributed energy resources DER. Long-term DER investments and short-term DER dispatch are typically determined by these models. This paper investigates the optimal cost analysis of a hybrid (photovoltaic-diesel) renewable energy system (HRES) in the Adrar region based on the Total Net Present Cost (TNPC). The Hybrid Optimization Model for Electric Renewable is used to perform the optimal cost analysis of HRES. Furthermore, the system is simulated for each time step for each year of the project's 20-year lifespan. The trade-off for this model, which captures battery storage levels from year to year, photovoltaic performance degradation, and diesel cost escalation above the inflation rate, is that the model is more precise, but the calculation takes longer. To begin, we ran the model without Multi-Year and used the Optimizer to find the best system design. The optimal system for the single-year model includes a Danvest generator with 760 kW, 200 kWh of recommended Li-ion storage, and a slightly lower COE of $0.309/kWh. Various scenarios have been simulated, taking into account variations in the power production of the gasified biomass generator, and various solutions to ensure the balance generation/consumption have been analyzed. Voir les détails
Mots clés : corrosion, Diesel, Financial planning optimization, Hybrid energy system (HES), Li-ion battery, Multi-year planning, Microgrid, Photovoltaic, Technical planning optimization, total net present cost
VARIABLE TIME TRIBOLOGICAL BEHAVIOR OF A DEPOSIT METAL E316L-17
Wear and corrosion are the main problems of mechanical elements in mechanical contact, and this results in enormous economic losses. This work describes the tribological effects during the variation of the friction time (1h, 3h, 12h and 24h) and the electrochemical behavior of the substrate solder coating. E316L-17/25CD4 using electric arc welding process. The tribological tests studied such as resistance to wear and coefficient of friction were carried out by a ball test with a friction speed of 20mm/s. The polarization curves were used to evaluate the electrochemical behavior (corrosion resistance) of the upper part of the hard coating. It was found that the wear resistance of E316L-17 increased with hardness. The corrosion current density of the coatings was determined. Voir les détails
Mots clés : E 316L-17, 25CD4 steel substrate, Electrochemical behavior, Tribological properties
A Robust Adaptive Fuzzy Fast Terminal Synergetic Voltage Control Scheme for DC/DC Buck Converter
In this paper, an adaptive fuzzy fast terminal synergetic voltage control scheme for DC/DC buck converter is proposed based on recently developed synergetic theory and a terminal attractor method. The advantages of presented synergetic control include the characteristics of finite time convergence, insensitive to parameters variation and chattering free phenomena. Rendering the design more robust, fuzzy logic systems are used to approximate the unknown parameters in the proposed controller without calling upon usual model linearization and simplifications. Taking the DC/DC buck converter in continuous conduction mode as an example, the algorithm of proposed synergetic control is analyzed in detail. All the simulation results demonstrate the effectiveness and the high dynamic capability of the proposed AF-FTSC control technique over the FTSC strategy. Voir les détails
Mots clés : synergetic control, fuzzy logic system, terminal technique, finite time convergence, DC/DC buck converter
Design of a Voltage Controller for a DC-DC Buck Converter Using Fractional-Order Terminal Sliding Mode Control Strategy
This paper suggests a fractional-order terminal sliding mode control (FO-TSMC) method for the output voltage regulation of a DC-DC buck converter influenced by disturbances, such as the variations of load resistance and input voltage. A this kind of a new fractional-order (FO) dynamic sliding surface is designed to avoid the drawback on integer-order (IO) terminal sliding mode control (IO-TSMC) method and guarantee the converter reach steady-state quickly without chattering even if it undergoes arbitrary random disturbances. The proposed FO-TSMC controller’s performance is compared against to both IO-TSMC and traditional SMC control approaches. Computer simulation results display that the novel FO-TSMC approach results in evenhanded output voltage regulation performance under widely input voltage variations and load changes. Voir les détails
Mots clés : Sliding Mode Control (SMC), terminal sliding mode control (TSMC), fractional-order (FO), DC-DC buck converter
Study of 5 % Fe-doped ZnO Powder Nanostructures as Transparent Ceramic for Optical Applications
microstructural properties using X-ray diffraction (XRD) for examined 5% Fe doped ZnO. The ZnO starting pure powder exhibited a hexagonal crystal structure with space group p63mc of ZnO, however with the introduction of 5 % Fe in the ZnO milled powder, the hexagonal ZnO phase remained un-changed, whereas the microstructural parameters were subject to significant variations due to the intro-duction of Fe atoms into the ZnO hexagonal matrix to replace oxygen ones. The size of crystallites and microstrains are found milling time dependent. For the applications of Zinc oxide, Zinc oxide (ZnO) is a potential candidate material for optics applications which has attracted considerable attention over past decades due to its wide potential applications such as ZnO photonic crystal slab, photo catalyst, UV absorption, solar cells, and so on. Voir les détails
Mots clés : ZnO; Microstructure; XRD; Mechanical Alloiyng; Optical Applications
Conception of a friction stir welding tool
Friction stir welding is a new process that allows a solid-state joining technology of metallic components. Applications and development within this approach has incr eased during the last decade. In this process, the geometry of friction tool plays a fundamental role to obtain suitable microstructures in the weld and the heat affected zones, thus it will be then possible to improve the strength and fatigue resistance of the joint. Among the articles related to the friction process, only few have treated the manufacturing process of the tool. In this work, we will focus on this last point. To increase the welding quality and the process reliability, the design of the tool includes a shaft-spring-based system aimed at avoiding premature damage, furthermore to allow the measure of applied friction pressure. Our improved friction tool has then been tested for applied this welding technique on Al-2024 and Al-7075 aluminium alloys sheets. The weld quality has been evaluated by means of a microstructure analysis and micro-hardness measurements. The ability to increase the welding speed, the changes of the crystalline plans orientation in the mixed part of thermo-mechanically affected zone and grains sizes observed in micrographics underline the effect of the pin geometry and its displacement. The micro-hardness curve shows good mechanical properties. Finally, the obtained results show a su ccessful welding with accep table quality and open new interesting perspectives. Voir les détails
Mots clés : Aluminium, conception, Friction Stir Welding, tool, Micro-hardness
PredictiveControl of a Grid Connected PVSystemsIncorporating Active Power FilterFunctionalities
This paper presents a multifunction operation of adouble stage grid connected photovoltaic system, with insertionthe active power filter (APF) functionalities. This system is usedto compensate the reactive power, suppression harmonicscurrents supply the nonlinear loads and inject the active powerinto grid. Our work is focused on the grid side, a perturbationand observation control is used to reach the maximum powerpoint tracking (MPPT) regardless of solar radiation. On the gridside, a modified instantaneous active and reactive poweralgorithm (P-Q) based on a multi-variable filter (MVF) is usedin order to identify the harmonics currents reference underdistorted source voltage condition, also a modified predictivecurrent control (PCC) algorithm is used to control the sourcevoltage inverter in order to ensure compensate reactive powerand harmonic currents, feed the non linear load and inject thesurplus generated power into the grid. In Matlab/Simulinksoftware, the proposed control scheme is investigated under loadchange and radiation change conditions. Simulation resultsshows that the proposed PCC of the APF guarantees a flexiblesettlement of real power amounts exchanges with the grid with ahigh power factor operation. Furthermore, the grid currentrecovers its sinusoidal waveform with a total harmonic distortion(THD) meet to IEEE-519 standard Voir les détails
Mots clés : Photovoltaic system (PV), activ power filter (APF), Predictive current control (PCC), active and reactive power theory (P-Q), multivariable filter (MVF), total harmonic distortion (THD)
Study and development of a new process for the treatment and purification of industrial effluents contaminated by metals by electrodeposition
Currently, Electrochemical methods find wide application in the treatment of industrial effluents to reduce their organic matter content, in inorganic sulfur compounds and nitrogen, or in harmful metals for the environment. Electrochemistry is not only applied to wastewater, but also on contaminated soils, incineration residues or sewage sludge wastewater from the metallurgical industry. Electrochemistry has proved its effectiveness, which allowed him to integrate the environmental industry. Environmental electrochemical technologies allow to control pollution, to recycle materials, to carry out the rehabilitation of sites, monitoring (monitors and sensors for gases and liquids), the efficient conversion of energy, the prevention of corrosion, removal of contaminants and disinfection of water. Electrochemical processes can therefore be efficient and economical when properly designed, and they integrate harmoniously with the environmental industry. These processes require compact installations and can thus integrate into existing industrial waste treatment chains. The present work aims so the elaboration of an electrochemical process of treatment and purification of industrial effluents contaminate with metals. Indeed, the use of this technique can allow both the elimination of these metals by electroplating on a cathode, a recovery of metals, a saving of precipitation reagents and a reduction in the amount of sludge to be removed, as well as surface treatments where the applications concern gold recovery, silver, copper, cadmium, nickel, zinc, iron and lead ... etc. The metal that can be recovered in the form of valorizable cathodes, which allows the depollution of the environment. This work requires in-depth studies of design considerations and the development of an electrolytic cell. Voir les détails
Mots clés : electrochemical, environment, pollution