Institutional repository of university M'Hamed Bougara Boumerdes
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Speech analysis–synthesis using sinusoidal representations: A review
No full textVarious speech analysis–synthesis representations have been suggested in the literature, and the more well-known ones are explored in this chapter, specifically, sinusoidal representation, harmonic/noise representation, and adaptive sinusoidal representations. Hence, the main objective of this chapter is to give a tutorial review of speech analysis–synthesis representations, by highlighting major improvements over these representations. It would be a desirable representation of speech that is relatively simple, flexible, high quality, and robust in re-synthesis. Emphasis will be given in adaptive sinusoidal representations, since they seem to be more promising and robust representations of speech
Modelling, controller design and implementation of a small-scale 3DOF helicopter using labVIEW and STM32F4xx microcontroller
No full text68 p.The 3DOF is a non-linear underactuated system. It is inspired from the Quanser 3DOF helicopter, however, the materials used and the dimensions as well as the motors are different therefore a model has to be define dan dimprove dfro mpreviou sworks .
The 3DOF small-scale helicopter is a map of a real CHINOOK helicopter. The aim of this work is to create a platform for testing and deploying the different controllers as it will serve as an educational and research platform. Both linear and nonlinear system identification techniques were used to derive a model. The nonlinear model was linearized around the region of operation and then an LQR controller was designed. The redundancies such as the ADC for generating the control action were removed to reduce delay times and hardware costs. The previous students utilized the NI DAQ 6221 M series for system identificatio nan ddurin gth erunnin go fth econtroller .I nou rcase ,th eN IDA Qwa sused solely for identificatio na si tfacilitate sth eimplementation ,verificatio n,visualizatio n,and logging. while the STM32F4 microcontroller was used for data acquisition during control operation. Introducing the STM32 removed the shortage of hardware counters. An LQR controller was designed, tuned, and tested. Finally, a GUI for logging the data in order to evaluate the performance of the controlled process was designed
Optimisation de la sécurité dans un atelier de préfabrication de la charpente métallique au sein de l’ENGTP par l’application de la méthode MADS-MOSAR
No full text79 p. : ill.Ce mémoire vise à identifier et à gérer les risques, prévenir les accidents et protéger la santé des travailleurs. L'étude a utilisé différentes méthodes d'analyse des risques, notamment ADD, AMDEC, Arbre logique, Diagramme d'Ishikawa et MADS-MOSAR. La démarche comprenait la décomposition du système, l'identification des sources de danger, l'analyse des dysfonctionnements, l'établissement d'un plan préventif et l'identification des barrières de sécurité. Les résultats ont permis d'identifier les principaux scénarios d'accidents potentiels et de proposer des recommandations pour les préveni
Étude de la possibilité d’augmentation du taux de charge de l’unité de Désasphaltage au Propane (raffinerie d’Arzew)
No full text84 p. : ill. ; 30 cmCe Mémoire se concentre sur l'étude de la possibilité d'augmenter le taux de charge de l'unité de désasphaltage au propane à la raffinerie d'Arzew. L'objectif est de passer d'un taux de charge de 85% à 100%, afin d'augmenter la production d'huile désasphaltée (DAO) tout en maintenant sa qualité. La première partie du mémoire présente une vue d'ensemble de la raffinerie RA1Z, de la chaîne de production des huiles de base et décrit l'unité de désasphaltage au propane avec une description de l’échangeur de chaleur et sa composition géométrique. La deuxième partie se concentre sur le contrôle de la qualité et de la quantité, dans le four, l'efficacité du four et le calcul de conception d'un nouvel échangeur de chaleur. En conclusion, des recommandations sont faites pour améliorer le processus et identifier les domaines de recherches futures
Calcul de vérification et de stabilité d’une colonne de distillation
No full text97 p. : ill. ; 30 cmL'objectif de cette étude est de concevoir une colonne de distillation de fractionnement afin d'évaluer sa résistance aux charges de pression et à la température maximale, conformément aux critères définis par l'ASME. Tout d'abord, un calcul analytique a été réalisé, suivi d'une modélisation numérique par la méthode des éléments finis à l'aide du logiciel « ANSYS ». La conception géométrique de la colonne a été effectuée avec Solidworks
An enhanced quasi-3D HSDT for free vibration analysis of porous FG-CNT beams on a new concept of orthotropic VE-foundations
No full textThe original primary objective of this study is to conduct a comprehensive investigation into the free vibration behavior of beams with porosity, reinforced by carbon nanotubes (CNTs). These beams are supported by an arbitrary orthotropic variable elastic foundation (AOVEF). The focus lies on understanding how the presence of porosity and CNT reinforcement, coupled with the complex support provided by the AOVEF, influences the vibration characteristics of the beams. In addition, we intend to examine the impact of a number of micromechanical models on the vibration properties of these beams. Four carbon nanotube variables are introduced to symbolize several CNT variations. CNTs’ mechanical properties are examined through a variety of micromechanical models. Shear deformation effects are considered into account in the framework of higher-order shear deformation (HSDT) beam theory. The equations of motion are constructed using Hamilton’s concept and the equation system for the FG-CNT beam with supported ends is solved via the Navier methodology. A new approach in elastic foundation modeling is the Arbitrarily Orthotropic Variable Elastic (AOP-VE) foundation. It builds on the Winkler layer concept but introduces the idea of a variable response along the length of the beam foundation. Unlike the Winkler-Pasternak model, AOP-VE allows for control over the directional properties of the Pasternak foundation. The study looks into multiple aspects, involving various distribution kinds of CNTs, the impact of Winkler and Pasternak factors, mode values, side-to-length ratio, porosity, and angle variation. The results indicate that these parameters have a major effect on the inherent vibration features of FG-CNT beams. The study results in various novel findings that improve the understanding of the subject topic and set a standard for future studies
Optimal design of wireless power transfer coils for biomedical implants using machine learning and meta-heuristic algorithms
No full textThe classical methods for optimizing wireless power transfer (WPT) systems using mathematical equations or finite element methods can be time-consuming and may only sometimes yield optimal designs. In order to overcome this challenge, this paper introduces a novel approach integrating machine learning techniques with meta-heuristic methods to design and optimize a miniaturized, high-efficiency WPT receiving coil for biomedical applications. The objective is to achieve dimensions below 20 mm, a depth of 30 mm within the tissue, and a frequency of 13.56 MHz. Our approach leverages a neural network (NN) model to predict efficiency based on geometric coil parameters, eliminating the need for complex equations. The NN was trained on a dataset generated via finite element method simulations. We employ two meta-heuristic algorithms, the genetic algorithm and the coyote optimization method, to find optimal parameters that maximize efficiency. Our NN model demonstrates exceptional accuracy, exceeding 97%. Furthermore, the proposed WPT coil design approach enhances transfer efficiency by up to 76%, significantly reducing computation time compared to classical methods. Finally, we validate our results using finite element simulation with Ansys Maxwell 3D
Geomechanical modeling to assess the injection-induced fracture slip-potential and subsurface stability of the Cambro-Ordovician reservoirs of Hassi Terfa field, Algeria
No full textThe in-situ stress state and the distribution of the critically stressed fractures have significant implications on optimum wellbore placement, production enhancement, fluid injection, and induced seismicity which largely influence the reservoir management strategies. This study presents a comprehensive geomechanical modeling to infer the likelihood of shear slippage of the optimally oriented weak planes in response to water injection in the deep Paleozoic oil reservoirs from the Hassi Terfa field, central Algerian Sahara. The ‘B-quality’ compressive failures, i.e., breakouts from the acoustic image log indicate the maximum horizontal stress azimuth as N114°E. The inferred in-situ stress magnitudes indicate a strike-slip tectonic regime in the study area. The reservoir is generally tight (porosity <8 %, permeability <0.4 mD) due to extensive silica cementation, however pre-existing closed to partially open natural fractures of variable geometries are identified on cores, thin sections, and image logs. The stress-based slip assessment indicates that none of the fracture geometries is critically stressed and hydraulically conductive at the initial reservoir stress state. The onset of slip on the critically oriented vertical fractures can initiate at 1200 psi of fluid injection at the reservoir level of ∼3500 m. The E-W to EES-WWN oriented fractures, parallel to the maximum horizontal stress azimuth, have a higher likelihood of being critically stressed during injection and therefore can contribute to the permeability enhancement. We restrict the practical injection threshold at 3000 psi, which can create tensile failures on the shale caprocks. We infer that the NE-SW and NNE-SSW striking, steeply dipping fractures and regional faults being perpendicular or at high angles to the regional maximum horizontal stress azimuth, are the most stable ones and therefore, less likely to slip within the practical injection limit
جامعة أمحمد بوقرة- بومرداس -كلية العلوم الإقتصادية، التجارية وعلوم التسيير
No full text130p.:ill.;30cm
The relationship between assessing audit risks and revealing creativeaccounting methods in accounting estimates: the perspective of Algerian external auditors
No full textNumerous studies have underscored the pivotal role of external auditors in identifying unfair estimates and preventing accounting manipulation. This is achieved by gathering sufficient and appropriate evidence when material misstatements are detected and verifying the existence of such misstatements. This study aims to explore the relationship between audit risk assessment (comprising the assessment of inherent risks, control risks, and the control of detection risks) and the detection of creative accounting methods in accounting estimates, from the perspective of Algerian external auditors. To fulfill this objective, a descriptive-analytical approach was adopted. The review encompasses the most significant findings of prior studies, supplemented by a field study involving the distribution of a questionnaire to a random sample of Algerian external auditors practicing the profession (n=300). The collected data were subsequently analyzed using the Statistical Package for the Social Sciences (SPSS26). The study concludes that there exists a positive and statistically significant relationship between the assessment of audit risks and the revelation of creative accounting methods in accounting estimates, according to Algerian external auditors. This implies that as audit risks are assessed, the likelihood of detecting creative accounting methods in accounting estimates increases, accounting for 62.8% of the variance. The remaining 37.2% is attributed to other factors. Notably, there is a positive relationship, varying in degree, between the assessment of audit risks and the detection of creative accounting methods. Assessing inherent risks has the highest impact, followed by assessing control risks and controlling detection risks. Additionally, the study identifies statistically significant differences in the perception of audit risks and creative accounting methods in accounting estimates among Algerian external auditors based on demographic characteristics within the study sample