Cet article est consacré à l’étude des performances de la génératrice asynchrone à cage double étoile (GASDE) en site isolé. Le système de commande est composé d’une GASDE raccordé à un bus continu et une charge en sortie de deux redresseurs à commande MLI. Une étude comparative entre la technique de commande conventionnelle et la commande adaptée basée sur l’introduction de la SVM-PI-flou et un nouvel estimateur de flux (flux virtuel statorique) afin d’améliorer la qualité d’énergie et d’atténuer les harmoniques du courant.

In this paper a dual direct torque control (DDTC) strategy with second-order sliding mode control (SOSMC) controller of the doubly fed Induction motor (DFIM) is presented in order to overcome some drawback such as ripples in torque, flux and to improve dual direct torque control (DDTC) performance toward the electrical parameters variations. This control strategy used in the doubly fed induction machine supplied, coupled by two voltage source inverters in rotor and stator sides witches are linked to two switching tables in order to determined the rotor and stator flux vector control. This controller based on super-twisting algorithm (STA). Comparative results between a classical controller (PI) and the proposed controller can prove the very satisfactory performance and robustness of this new controller.

The direct power control of the doubly fed induction generator using conventional controllers is characterized by unsatisfactory performance: high ripples of stator powers and sensitivity to parametric variations. Among the most evoked control strategies adopted in this field to overcome these drawbacks presented in classical drive, it is worth mentioning the use of the higher law sliding mode developed on the super twisting algorithm associated with the fuzzy logic control in order to realize optimal command performance, Finally, the efficiency of the envisaged control scheme, is investigated against. The proposed regulation scheme is efficient in reducing the powers ripples; successfully suppress chatter and the effects of parametric variations that do not affect the performance of the regulation.

This paper proposes the fundamental aspects of hybrid nonlinear control which is composed of the super twisting algorithm (STA) based second order sliding mode control applying fuzzy logic method (FSOSMC), with pertinent simulation results for a doubly fed induction machine (DFIM) drive. To minimize chattering effect phenomenon due to Signum function employed in sliding mode algorithm, a new method is proposed. This technique consists in replacing the signum function by fuzzy switching function in the SOSMC to minimize flux and torque ripples. This FSOSMC is associated to the double direct torque control DDTC of the doubly fed induction machine (DFIM) by combining the advantages of fuzzy logic (FL) and the advantages of super-twisting sliding mode. The FSOSMC-DDTC strategy is compared with a PI-DDTC and SOSMC-DDTC. Simulation results demonstrate good efficiency and excellent robustness of the hybrid nonlinear controller.

L’article décrit la conception et la mise en øe}uvre en temps réel d’une commande non linéaire appliquée à un système de conversion de l’énergie éolienne (SCEE). La commande backstepping a été mise en øe}uvre pour améliorer les performances du système de conversion éolienne basé sur un générateur synchrone à aimants permanents (PMSG) connecté au réseau. Deux convertisseurs statiques assurent la connexion au réseau et sont contrôlés par la modulation de largeur d’impulsion (MLI). L’algorithme de contrôle proposé assure un contrôle de vitesse adéquat pour extraire la puissance maximale. Une description détaillée des lois de contrôle du backstepping basées sur la technique de stabilité de Lyapunov a été exposée. Les résultats obtenus par l’application de cette approche ont clairement répondu aux exigences de robustesse et de suivi des références même dans des conditions de vent fluctuants, et ont confirmé l’efficacité d’un tel contrôle dans les modes de fonctionnement statique et dynamique.

To enhance the robustness and dynamic performance of a self-excited induction generator (SEIG) used in a stand-alone wind energy system (WES), a virtual flux oriented control (VFOC) based on nonlinear super-twisting sliding mode control (STSMC) is adopted. STSMC is used to replace the conventional proportional-integral-Fuzzy Logic Controller (PI-FLC) of the inner current control loops. The combination of the proposed control strategy with space vector modulation (SVM) applied to a PWM rectifier brings many advantages such as reduction in harmonics, and precise and rapid tracking of the references. The performance of the proposed control technique (STSMC-VFOC-SVM) is verified through simulations and compared with the traditional technique (PI-FLC-VFOC-SVM). It shows that the proposed method improves the dynamics of the system with reduced current harmonics. In addition, the use of a virtual flux estimator instead of a phase-locked loop (PLL) eliminates the line voltage sensors and thus increases the reliability of the system.

In the petroleum industry, equipments must be maintained properly to meet the adequate reliability standards in order to achieve the desired business goals in terms of productivity, safety and environmental protection. This article offers a new approach focused on risk analysis to select a better maintenance strategy. The proposed approach consists of three stages. In the first step, we identify the accident scenarios that could lead to the loss of production and damage to the environment. In the second step, we estimate the frequency of occurrence of these scenarios. In the third step, we calculate the economic losses and environmental taxes. Finally, an appropriate maintenance strategy is proposed, taking into account the evaluation results obtained by the previous steps. A case study illustrates the proposed approach and shows that the latter constitutes an important decision support tool to improve the existing maintenance strategy to comply with regulations and standards in term of productivity, reduction of costs and environmental protection.

In the petroleum industry, equipments must be maintained properly to meet the adequate reliability standards in order to achieve the desired business goals in terms of productivity, safety and environmental protection. This article offers a new approach focused on risk analysis to select a better maintenance strategy. The proposed approach consists of three stages. In the first step, we identify the accident scenarios that could lead to the loss of production and damage to the environment. In the second step, we estimate the frequency of occurrence of these scenarios. In the third step, we calculate the economic losses and environmental taxes. Finally, an appropriate maintenance strategy is proposed, taking into account the evaluation results obtained by the previous steps. A case study illustrates the proposed approach and shows that the latter constitutes an important decision support tool to improve the existing maintenance strategy to comply with regulations and standards in term of productivity, reduction of costs and environmental protection.

Workplace accidents (WAs) are and will remain a major concern for organizations’ managers. Their control requires putting in place a prevention strategy framed by several factors (human / social, economic, regulatory ...). The successful implementation of this strategy is conditioned on the ground, by the junction of three essential stages, namely: the analysis, evaluation and control of WAs. These three stages are interdependent where a successful control of an action plan is conditioned by a thorough assessment of an accident risk criticality. The latter depends on a good analysis of the accident. Indeed, a good analysis of WAs largely conditions their prevention strategy and that is why the analysis of WAs occupies a prominent place in such strategies. WAs analysis is conducted using appropriate models referred to as "WAs analysis models". Among those cited in the literature, we quote the model 24 that is a contemporary and more systematic model compared to other models. In this context that this article fits in, which aims to highlight its multiple contributions for the analysis of WAs.

The workplace, and more particularly the healthcare sector, has recently experienced a staggering increase in violence. These aggressive behaviors are resulting in considerable consequences on healthcare workers, both in terms of mental and physical health. In light of this observation, this study aims to provide a quantitative analysis of the potential causes leading to violence in Algerian hospitals, which have become the place where tensions arise, especially during these uncertain times caused by the COVID-19 pandemic. Therefore, we started with conducting a field survey, in order to highlight the main causes behind this violence, as well as the strategy in terms of how it is managed as a risk. Then we used ISHIKAWA diagrams to classify predefined causes into several categories and anticipate the likelihood of such violent behaviors. Finally, the results of this study revealed that working conditions were the main cause of violence in Algerian hospitals. In order to remedy this gap, we recommend improving the healthcare staff well-being, as well as prioritizing proactive measures preventing violent behaviors.

The Safety Instrumented System (SIS) is an automated system used to implement one or more safety instrumented functions. A SIS, like the Emergency Shutdown (ESD) system, consists of any combination of sensor(s), safety PLC(s) and final element(s) (e.g. ESD valves). ESD valves are the last line of defense against risks, although the ESD valve has high performance, the data (based on expert judgment and OREDA database) indicates that ESD valves failures are the most critical in the ESD systems. In order to improve the reliability and safety of these valves, we applied the FMEDA diagnostic technique. We started with a decomposition of the ESD valve to the subsystems and we identified their functions. Then we described the failure modes, their mechanisms, their sites and their effects. Then we identified the impact of each failure mode according to the criticality classes and identified the failure rates and their class according to the criticality and the detectability by automatic diagnosis of each mode and from the failure rates we calculated the Safe Failure Fraction (SFF) and Safety Integrity Level (SIL) required and we concluded that the actuator subsystem is the most critical system. Finally, we proposed preventive and protective measures to eliminate or reduce the risk of failure.

In recent decades, vascular surgery has seen the arrival of endovascular techniques for the treatment of vascular diseases such as aortic diseases (aneurysms, dissections, and atherosclerosis). The 3D printing process by addition of material gives an effector of choice to the digital chain, opening the way to the manufacture of shapes and complex geometries, impossible to achieve before with conventional methods. This chapter focuses on the bio-design study of the thoracic aorta in adults. A bio-design protocol was established based on medical imaging, extraction of the shape, and finally, the 3D modeling of the aorta; secondly, a bio-printing method based on 3D printing that could serve as regenerative medicine has been proposed. A simulation of the bio-printing process was carried out under the software Simufact Additive whose purpose is to predict the distortion and residual stress of the printed model. The binder injection printing technique in a Powder Bed Printer (PBP) bed is used. The results obtained are very acceptable compared with the results of the error elements found.

This work is a study of the elastic fields’ effect (stresses and displacements) caused by dislocations networks at a heterostructure interface of a InAs / GaAs semiconductors thin system in the cases of isotropic and anisotropic elasticity. The numerical study of this type of heterostructure aims to predict the behavior of the interface with respect to these elastic fields satisfying the boundary conditions. The method used is based on a development in Fourier series. The deformation near the dislocation is greater than the other locations far from the dislocation.     

In the industry, automated inspection is important for ensuring the high quality and allows acceleration of procedures for quality control of parts or mechanical assemblies. Although significant progress has been made in precision machining of complex surfaces, precision inspection of such surfaces remains a difficult problem. Thus the problem of the conformity of the parts of complex geometry is felt more and more. Motivated by the need to increase quality and reduce costs, and supported by the progress made in the field of it as well as the automation of production which in recent years has seen a considerable evolution in all these stages: from design to control through manufacturing. Due to, we used a 3D computer aided inspection technique on a physical gear using a coordinate measuring machine equipped with a “PC-DMIS” measurement and inspection software. Our work consists in developing a procedure for inspection for reproduction of gear profile by reconstruction of a circle involute gear from a cloud point’s measurement. In order to obtain a reliable result. In this works, we design the CAD-model of the part as accurately as possible (using a mathematical model) and matched with the 3D points cloud that represents the measurement that obtained from scanner. we compare the measurement cloud points from coordinate measurement machine with the mathematical model of construction by ICP (Iterative Closest Point) methods in order to obtain a conformed result and to show the impact of the dimensional inspection and geometric.

Designing and manufacturing lattice structures with Topology Optimization (TO) and Additive Manufacturing (AM) techniques is a novel method to create light-weight components with promising potential and high design flexibility. This paper proposes a new design of lightweight-graded lattice structures to replace the internal solid volume of the turbine blade to increase its endurance of high thermal stresses effects. The microstructure design of unit cells in a 3D framework is conducted by using the lattice structure topology optimization (LSTO) technique. The role of the LSTO is to find an optimal density distribution of lattice structures in the design space under specific stress constraints and fill the inner solid part of the blade with graded lattice structures. The derived implicit surfaces modelling is used from a triply periodic minimal surfaces (TPMS) to optimize the mechanical performances of lattice structures. Numerical results show the validity of the proposed method. The effectiveness and robustness of the constructed models are analysed by using finite element analysis. The simulation results show that the graded lattice structures in the improved designs have better efficiency in terms of lightweight (33.41–40.32%), stress (25.52–48.55%) and deformation (7.35–19.58%) compared to the initial design.