A new characterization and a Rodrigues formula for generalized Hermite orthogonal polynomials

In this paper, we consider the raising operator Rξ = ξ Tμ + xI, ξ ̸= 0, where Tμ and I are the Dunkl operator and the identity operator respec- tively. Our purpose is to determine all monic orthogonal polynomials se- quences {Pn(x)}n≥0 such that the sequence of polynomials {(Rξ Pn)(x)}n≥0 is also orthogonal. We prove that the only sequence of polynomials sat- isfying this condition is, up to a dilation, the generalized Hermite poly- nomial sequence. Then, we explore our result to deduce a Rodrigues formula for the generalized Hermite polynomials sequence

Analyzing the Effects of MBPSS on the Transit Stability and High-Level Integration of Wind Farms during Fault Conditions

As the demand for renewable energy continues to increase, wind power has emerged as a prominent source of clean energy. However, incorporating wind energy into the power generation system at a high level can significantly impact the dynamic performance of the power system, resulting in increased uncertainties during operation. This study investigated the effectiveness of the Multi-Band Power System Stabilizer (MBPSS), a new power system stabilizer, in suppressing dynamic oscillations in a multi-machine power system connected to a wind farm. This research focused on analyzing the transient stability of a nine-bus network, commonly known as the Western System Coordinating Council (WSCC), integrated with a Doubly Fed Induction Generator (DFIG) using MATLAB/Simulink. The study evaluated the dynamic performance of the proposed system under fault conditions, including Line-to-Line-to-Line-to-Ground (LLLG) faults. Simulation results showed that MBPSS effectively dampened oscillations and improved the stability of the power system, even in the presence of severe faults and high-level integration of wind farms

Elaboration and Characterization of Recycled PP/Clay Nanocomposites

In this paper, the elaboration and characterization of recycled polypropylene/Tunisian clay nanocomposites has been investigated. When recycled, polypropylene polymer is degraded and has poorer mechanical and rheological properties. To overcome this problem, we proposed to incorporate Tunisian clay nanoparticles in recycled polypropylene (rPP) matrix. The incorporation of Tunisian clay was performed in molten state using maleic anhydride grafted polypropylene (PP-g-MA) as compatibilizer. The dispersion of clay in rPP polymer was evaluated by scanning electron microscopy and Fourier transformed infrared spectroscopy. Thus, Tunisian clay was more dispersed in nanocomposites with the increase of Tunisian clay loading. In dead, the incorporation of silicate layers gave rise to a considerable increase of the static viscosity demonstrating the reinforcing effect of Tunisian clay nanofillers on rPP matrix. However, the increasing trend of morphological and rheological properties is lower when the clay content exceeds 5%

Synthesis of composites based on recycled PP - Clay for textiles applications

Le polypropylène (PP) est un thermoplastique très utilisé dans la production industrielle. Il répond aux exigences de nombreux cahiers de charges grâce à ses excellentes propriétés tout en ayant une des plus faibles densités. Cependant, ses performances s’avèrent parfois insuffisantes lors de son recyclage, notamment en ce qui concerne ses propriétés thermiques et mécaniques. Pour pouvoir le réutiliser, le polymère doit être renforcé. Entre autres, l’adjonction de particules de renfort à la matrice de PP recyclé semble être une méthode efficace qui permet d’obtenir un composite avec de bonnes propriétés.Ainsi, l'objectif de notre thèse a été d'étudier l'influence de la concentration en argile tunisienne modifiée chimiquement sur les comportements thermo-mécaniques et rhéologiques du PP recyclé. Les divers mélanges mis en œuvre par extrusion ont été filés à l’aide d’un procédé de filage à l’état fondu. Une étude morphologique, thermo-mécanique et tinctoriale de la structure filamentaire élaborée est effectuée. Toutes ces approches nous ont permis de maîtriser les paramètres de réutilisation du PP et d'ouvrir la voie à de nouvelles applications, comme par exemple en tant que filtres pour les stations de retraitement des rejets de teinture dans le domaine de l’ennoblissement.Polypropylene PP is considered to be one of the most promising polyolefin polymer in compounding applications thanks to its good processability and excellent properties, as well as its low cost and density. This polymer is widely used in several applications, such as automotive components, aerospace, plastic parts, food packaging and geotextiles. Nevertheless, the performance of reused PP is proved to be insufficient in many applications, particularly with regard to its thermo-mechanical properties. However, recycled PP could acquire desired properties by incorporating fillers into polymer matrix. The objective of the thesis initially was studied the influence of organoclay on the physical, rheological, mechanical and thermal stability of recycled PP. In the following step, the prepared composite was then made into filamentsvia a melt spinning technique. The morphological and thermo-mechanical properties as well as the dyeability of the prepared filament were evaluated. The objective here is to exploit the elaborated composite in textile applications. Finally, all of its approaches and scientific studies allowed us to control the parameters of PP reuse and to open the way for new applications such as filters for treatment stations of textile dyeing waste in Tunisia

Synthèse de composites à base de PP recyclé - Argile pour des applications textiles

Polypropylene PP is considered to be one of the most promising polyolefin polymer in compounding applications thanks to its good processability and excellent properties, as well as its low cost and density. This polymer is widely used in several applications, such as automotive components, aerospace, plastic parts, food packaging and geotextiles. Nevertheless, the performance of reused PP is proved to be insufficient in many applications, particularly with regard to its thermo-mechanical properties. However, recycled PP could acquire desired properties by incorporating fillers into polymer matrix. The objective of the thesis initially was studied the influence of organoclay on the physical, rheological, mechanical and thermal stability of recycled PP. In the following step, the prepared composite was then made into filamentsvia a melt spinning technique. The morphological and thermo-mechanical properties as well as the dyeability of the prepared filament were evaluated. The objective here is to exploit the elaborated composite in textile applications. Finally, all of its approaches and scientific studies allowed us to control the parameters of PP reuse and to open the way for new applications such as filters for treatment stations of textile dyeing waste in Tunisia.Le polypropylène (PP) est un thermoplastique très utilisé dans la production industrielle. Il répond aux exigences de nombreux cahiers de charges grâce à ses excellentes propriétés tout en ayant une des plus faibles densités. Cependant, ses performances s’avèrent parfois insuffisantes lors de son recyclage, notamment en ce qui concerne ses propriétés thermiques et mécaniques. Pour pouvoir le réutiliser, le polymère doit être renforcé. Entre autres, l’adjonction de particules de renfort à la matrice de PP recyclé semble être une méthode efficace qui permet d’obtenir un composite avec de bonnes propriétés.Ainsi, l'objectif de notre thèse a été d'étudier l'influence de la concentration en argile tunisienne modifiée chimiquement sur les comportements thermo-mécaniques et rhéologiques du PP recyclé. Les divers mélanges mis en œuvre par extrusion ont été filés à l’aide d’un procédé de filage à l’état fondu. Une étude morphologique, thermo-mécanique et tinctoriale de la structure filamentaire élaborée est effectuée. Toutes ces approches nous ont permis de maîtriser les paramètres de réutilisation du PP et d'ouvrir la voie à de nouvelles applications, comme par exemple en tant que filtres pour les stations de retraitement des rejets de teinture dans le domaine de l’ennoblissement

Etude de formulation et de comportement mécanique des Bétons Compactés au Rouleau (BCR) (Applications routières - Cas des matériaux de gisements locaux)

Le présent travail de recherche comporte une étude sur le Béton Compacté au Rouleau (BCR) en vue d'une application en technique routière et en utilisant des matériaux de gisements locaux avec la spécificité d un faible dosage en ciment. L'étude a traité le problème de formulation à travers les méthodes graphiques, semi-empiriques et le Modèle d'Empilement Compressible MEC. On a introduit aussi dans ce travail, l utilisation des granulats spéciaux du type Sidérite et l'addition des adjuvants dans la formulation du BCR. La rhéologie du BCR frais et la sensibilité de ce mélange au phénomène de densification ont été étudiées en proposant une nouvelle approche basée sur la Compactabilité pour la prédiction de la rhéologie de ce matériau. La caractérisation du BCR durci a été effectuée moyennant des mesures expérimentales de résistances et de modules élastiques E ainsi que des essais ultrasoniques. Les résultats expérimentaux sont comparés avec ceux obtenus par des prédictions à travers des modèles tels que ceux de Feret-De Larrard-Tondat, ACI, Ouellet et Oluokun. Certains modèles sont jugés fiables pour la formulation et les prédictions des résistances du BCR par contre nous avons proposé d'autres qui sont adaptés à ce mélange et à ces composants. Une modélisation en 3D d'une chaussée rigide en BCR, en utilisant le code de calcul par éléments finis "Abaqus 6.7", a été effectuée en introduisant à ce code la loi de comportement correspondant de ce matériau. Cette modélisation a été faite pour plusieurs cas de chargements sur des dalles en BCR. Une convergence a été déduite entre les résultats obtenus, de la répartition en 3D des contraintes et des déformations dans les dalles de BCR et ceux obtenus par les autres méthodes 2D telles que celles de Westergaard, d'Ioannides et al.This research work presents a study of the Roller Compacted Concrete (RCC) for an application in road engineering. The RCC was prepared using materials of local quarries with the specificity of a low cement proportioning. The study dealt with the formulation problem through graphics, semi-empirical methods and the Compressible Packing Model CPM . We introduced also, into this work, the use of the special aggregates type Siderite and the addition of the admixtures in the formulation of the RCC. The rheology of the fresh RCC and the sensitivity of this mixture to the compaction phenomenon were studied by proposing a new approach, based on Compactability, for the prediction of this material rheology. The characterization of the hardened RCC was carried out by experimental measurements of strengths and elastic modules E as well as ultrasonic tests. The experimental results were compared with those obtained by predictions through models like those of Feret-De Larrard-Tondat, ACI, Ouellet and Oluokun. Some models were considered to be reliable for the formulation and the predictions of the RCC strengths. However, we proposed others models which were adapted to this mixture and their components. A 3D modelling of a rigid RCC pavement, using the computer code of finite elements "Abaqus 6.7" was achieved by introducing to this code the behaviour law corresponding to this material. This modelling was made for several cases of loadings on RCC slabs. A convergence was deduced between the results obtained, of the distribution in 3D of the stresses and of the deformations in the RCC slabs and those obtained by the other 2D methods such as that of Westergaard, of Ioannides et al.BETHUNE-BU Sci. appli. et éco. (621192101) / SudocSudocFranceF

Fault Analysis of a Small PV/Wind Farm Hybrid System Connected to the Grid

The dynamic modeling, control, and simulation of renewable energy sources connected to the electrical grid are investigated in this study. Photovoltaic (PV) systems and wind systems connected to the power grid via the point of common connection (PCC) were the only two systems included in our study. Simulation and control methodologies are provided. For both PV arrays, the method of extracting maximum power point tracking (MPPT) is utilized to obtain the highest power under standard test conditions (STC: 1000 W/m2, 25 °C). A power electronics converter that can transform DC voltage into three-phase AC voltage is required to connect a PV system to the grid. Insulated gate bipolar transistors (IGBTs) are utilized in a three-level voltage source converter (VSC). The distribution network is connected to this three-phase VSC by way of a step-up transformer and filter. During synchronous rotation in the d−q reference frame, the suggested control for the three-level solar power system that is connected to the grid is constructed. To obtain a power factor as near to one as possible, the phase-locked loop (PLL) is employed to align the angle of the power grid voltage with the angle of the current coming from the inverter. Squirrel-cage induction generators (SCIGs), which are utilized as fixed speed generators and are linked directly to the power network, are the foundation of the wind system. Additionally, a pitch angle control approach is suggested to keep the wind turbine’s rotor speed stable. MATLAB/Simulink software is utilized to model and simulate the suggested hybrid system. Under fault scenarios such as the line to line to line to ground fault (LLLG fault), the suggested hybrid system’s dynamic performance is examined. The simulation results prove the ability to manage the small hybrid system that combines solar and wind power, as well as its dynamic performance