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Performance Comparison of Modulation Techniques for Modular Multilevel Converter
No full textInternational audienceThis paper presents a comparative study of four different modulation techniques for Modular Multilevel Converters (MMCs). The modulation techniques include the usual Pulse Width Modulation (PWM) technique, the Integral Modulation technique (IM), and an extended version of both methods aiming to reduce the number of commutations per second, while keeping the load current waveform quality. The study evaluates the advantages and drawbacks of each method and compares their performance in terms of waveform quality, capacitor voltage ripples, and number of commutations per second using a software simulation
Modulation of innate immune defenses by Bacilli : A Drosophila melanogaster perspective.
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Chimie des processus biologiques
No full textInternational audienceCours – Chimie biologique : tendances en enzymologie Le cours n’a pu être donné en raison de la crise sanitaire du printemps 2020. Cours à l’extérieur – Chimie et énergie Université Saint-Joseph, Beyrouth (Liban), en automne 2019 Cours 1 – Chimie et défis énergétiques du xxie siècle : une introduction Dans ce premier cours/séminaire ont été présentés, dans leur grande généralité et en guise d’introduction, les grands enjeux de la transition énergétique : la fin des énergies fossi..
ASD with high pelvic retroversion develop changes in their acetabular orientation during walking
No full textInternational audienceIntroduction: It was hypothesized that pelvic retroversion in Adult Spinal Deformity (ASD) can be related to an increased hip loading explaining the occurrence of hip-spine syndrome.Research question: How pelvic retroversion can modify acetabular orientation in ASD during walking?Methods: 89 primary ASD and 37 controls underwent 3D gait analysis and full-body biplanar X-rays. Classic spinopelvic parameters were calculated from 3D skeletal reconstructions in addition to acetabular anteversion, abduction, tilt, and coverage. Then, 3D bones were registered on each gait frame to compute the dynamic value of the radiographic parameters during walking. ASD patients having a high PT were grouped as ASD-highPT, otherwise as ASD-normPT. Control group was divided in: C-aged and C-young, age matched to ASD-hightPT and ASD-normPT respectively.Results: 25/89 patients were classified as ASD-highPT having a radiographic PT of 31° (vs 12° in other groups, p < 0.001). On static radiograph, ASD-highPT showed more severe postural malalignment than the other groups: ODHA = 5°, L1L5 = 17°, SVA = 57.4 mm (vs 2°, 48° and 5 mm resp. in other groups,all p < 0.001). During gait, ASD-highPT presented a higher dynamic pelvic retroversion of 30° (vs 15° in C-aged), along with a higher acetabular anteversion of 24° (vs 20°), external coverage of 38° (vs 29°) and a lower anterior coverage of 52° (vs 58°,all p < 0.05).Conclusion: ASD patients with severe pelvic retroversion showed an increased acetabular anteversion, external coverage and lower anterior coverage during gait. These changes in acetabular orientation, computed during walking, were shown to be related to hip osteoarthritis
Estimations d'erreur a posteriori pour le couplage des équations de Navier-Stokes avec l'équation de convection-diffusion-réaction
No full textThe exact solution of partial differential equations is generally difficult to calculate. For this reason, numerical methods have been developed, which allow to find approximate solutions. In this thesis, we are interested in the unsteady incompressible Navier-Stokes equations which describe the behaviour of a fluid. We choose a case where the force applied to the fluid as well as its viscosity depend on another variable, for example its temperature or the concentration of a certain material in the fluid. So we need to couple the Navier-Stokes equations with the convection-diffusion-reaction equation which describes the transport of the additional variable with the fluid velocity. Our study was developed along three lines. The problem is discretized using the Euler scheme for the time discretization and the "P1-bubble/P1/P1" finite elements for the space discretization. In a first step, we study the error estimate of the coupled problem assuming that the diffusion coefficient in the transport equation is a constant. This estimate involves two types of error indicators, the first related to the discretization in time and the second to the discretization in space. In a second step, we take up the study of the coupled problem, assuming this time that the diffusion coefficient also depends on the transported variable. We start by showing the existence and the conditional uniqueness of the solution of this new problem. Then we establish the error estimate of the latter by following the same steps as those carried out in our first study. Finally, numerical simulations are elaborated using FreeFem++ software to validate the theoretical results. The time and space adaptive simulations demonstrate the usefulness of the approach.La solution exacte des équations aux dérivées partielles est en général difficile à calculer. Pour cela, des méthodes numériques ont été développées, qui nous permettent de trouver des solutions approchées. Dans cette thèse, nous nous intéressons aux équations de Navier-Stokes incompressibles instationnaires qui décrivent le comportement d’un fluide. Nous choisissons un cas où la force appliquée au fluide ainsi que la viscosité du fluide dépendent d’une autre variable, par exemple sa température ou la concentration d’une certaine matière dans ce fluide. Alors nous avons besoin de coupler les équations de Navier-Stokes avec l’équation de convection-diffusion-réaction qui décrit le transport de la variable supplémentaire à la vitesse du fluide. Notre étude s’est développée à trois niveaux. Le problème est tout d’abord discrétisé en utilisant le schéma d’Euler pour la discrétisation en temps et les éléments finis " P1-bulle/ P1/ P1" pour la discrétisation en espace. Dans un premier temps, nous étudions l’estimation d’erreur a posteriori de notre problème de couplage en supposant que le coefficient de diffusion dans l’équation de transport est une constante. Cette estimation fait apparaître deux types d’indicateurs d’erreur, le premier lié à la discrétisation en temps et le second lié à discrétisation en espace. Dans un second temps, nous reprenons l’étude du problème couplé en supposant cette fois que le coefficient de diffusion dépend aussi de la variable transportée. Nous commençons par montrer l’existence et l’unicité conditionnelle de la solution de ce nouveau problème. Puis nous établissons l’estimation d’erreur a posteriori de ce dernier en suivant des étapes identiques à celles effectuées lors de notre première étude. Finalement, des simulations numériques sont élaborées à l’aide du logiciel FreeFem++ pour valider les résultats théoriques. Les simulations adaptatives en temps et en espace démontrent l’utilité de la démarche
Spinopelvic Adaptations in Standing and Sitting Positions in Patients With Adult Spinal Deformity
No full textInternational audiencePurposeTo describe spinopelvic adaptations in the standing and sitting positions in patients with adult spinal deformity (ASD).MethodsNinety-five patients with ASD and 32 controls completed health-related quality of life (HRQOL) questionnaires: short form 36 (SF36), Oswestry Disability Index (ODI), and visual analog scale (VAS) for pain. They underwent biplanar radiography in both standing and sitting positions. Patients with ASD were divided into ASD-front (frontal deformity Cobb > 20°, n = 24), ASD-sag (sagittal vertical axis (SVA) > 50 mm, pelvic tilt (PT) > 25°, or pelvic incidence (PI)-lumbar lordosis (LL) > 10°, n = 40), and ASD-hyper thoracic kyphosis (TK >60°, n = 31) groups. Flexibility was defined as the difference (Δ) in radiographic parameters between the standing and sitting positions. The radiographic parameters were compared between the groups. Correlations between HRQOL scores were evaluated.ResultsAll participants increased their SVA from standing to sitting (ΔSVA<0), except for patients with ASD-sag, who tended to decrease their SVA (78-62 mm) and maximize their pelvic retroversion (27-40° vs 10-34° in controls, p<0.001). They also showed reduced thoracic and lumbar flexibility (ΔLL = 3.4 vs 37.1°; ΔTK = −1.7 vs 9.4° in controls, p<0.001). ASD-hyperTK showed a decreased PT while sitting (28.9 vs 34.4° in controls, p<0.001); they tended to decrease their LL and TK but could not reach values for controls (ΔLL = 22.8 vs 37.1° and ΔTK = 5.2 vs 9.4°, p<0.001). The ASD-front had normal standing and sitting postures. ΔSVA and ΔLL were negatively correlated with the physical component scale (PCS of SF36) and ODI (r = −0.39 and r = −0.46, respectively).ConclusionPatients with ASD present with different spinopelvic postures and adaptations from standing to sitting positions, with those having sagittal malalignment most affected. In addition, changes in standing and sitting postures were related to HRQOL outcomes. Therefore, surgeons should consider patient sitting adaptations in surgical planning and spinal fusion. Future studies on ASD should evaluate whether physical therapy or spinal surgery can improve sitting posture and QOL, especially for those with high SVA or PT
Coordinated Framework for Spectrum Allocation and User Association in 5G HetNets With mmWave
No full textInternational audienceDense deployment of small cells operating on different frequency bands based on multiple technologies provides a fundamental way to face the imminent thousand-fold traffic augmentation. This heterogeneous network (HetNet) architecture enables efficient traffic offloading among different tiers and technologies. However, research on multi-tier HetNets where various tiers share the same microwave spectrum has been well-addressed over the past years. Therefore, our work is targeted towards novel multi-tier HetNets with disparate spectrum (microwave and millimeter wave). In fact, despite the huge capacity brought by millimeter-wave technology, the latter will fail to provide universal coverage, especially indoor, and so mmWave will inevitably co-exist with a traditional sub-6GHz cellular network. In this work, we propose a coordinated user association and spectrum allocation by resorting to non-cooperative game theory. In fact, in such an arduous context, efficient distributed solutions are imperative. Extensive simulation results show the precedence of our coordinated approach in comparison with state-of-the-art heuristics. Moreover, we evaluate the impact of various network parameters, such as mmWave density, cell load, and user distribution and density, offering valuable guidelines into practical 5G HetNet design. Finally, we assess the benefit brought by massive MIMO for mmWave in such a highly heterogeneous setting
Health related quality of life and perceived social support in French and Lebanese MS patients: A comparative study
No full textInternational audienceBackground: The perception of diagnosis announcement, the social support and the coping strategies seem to be determining factors for the quality of life of multiple sclerosis (MS) patients, with possible transcultural variations. This study explores these psychosocial dimensions in Lebanese and French MS patients.Methods: For this cross-sectional multi-center study, 8 questionnaires were used to assess quality of life, family support, coping strategies, mood, fatigue, stress, and hopelessness in MS patients. 7 were translated into Arabic and then back translated into French. These were administered to a group of Lebanese MS patients and compared to an MS sample from France. The data was collected for both populations and analyzed.Results: A total of 107 patients were included, 46 Lebanese and 61 French. The majority of MS patients were young females with a high level of education, relapsing remitting form of MS and a low level of disability. Both populations exhibited comparable quality of life and answers on the questionnaires regarding mood disorders, hopelessness, and perceived stress. However, the French patients had significantly more fatigue. Perceived social support given by family was considered greater in the French group compared to the Lebanese one. Also, maladaptive coping strategies (such as self-distraction, denial, behavioral disengagement, substance use, self-blame, venting) were used more frequently by the French population compared to the Lebanese, and this correlated with higher anxiety scores. Diagnosis communication was overall brief, informative, and satisfying in both populations.Conclusion: This study highlighted transcultural differences between French and Lebanese MS patients mainly in social support and coping strategies
Multi-objective Optimization of a DC Microgrid with a Back-up Diesel Generator
No full textInternational audienceNowadays, microgrid applications are proliferate all around the world. Owing to many grounds, such the ease of control, the high efficiency and reliability, the improvement of power electronics devices, the rise of DC type loads and sources, etc. researchers' interest was diverted from AC to DC microgrids. Yet, on a global control and management level, several challenges are confronted. A variety of objectives can be achieved by controlling the power flow of each of the distributed energy sources. By means of this, an optimization problem is formulated and solved using heuristic methods such the genetic algorithm (GA), the particle swarm optimization (PSO), the pattern search (PS), etc. However, other techniques were exploited in the literature such the dynamic programming (DP) which is a stepby-step optimization algorithm. In this paper, a (DP) technique is applied to solve a multi-objective optimization problem. Two objectives are set: DC microgrid operation cost minimization, and pollutant gas emissions reduction. A sole cost function is established, and weights are assigned to each of the predefined goals. Besides, each objective function is detailed apart, and several constrains are set. Two simulations tests are performed to prove the convergence, and the viability of the applied (DP) technique. Finally, different weights are selected in each of simulation tests to validate the effectiveness, and robustness of the (DP) in solving such problems
Intensification of Bioethanol Production from Different Lignocellulosic Biomasses, Induced by Various Pretreatment Methods: An Updated Review
No full textInternational audienceWhile world energy demand has certainly decreased with the beginning of the COVID-19 pandemic in 2020, the need has been significantly on the rise since 2021, all as the world’s fossil fuel resources are depleting; it is widely accepted that these resources emit greenhouse gases (GHG), which are the leading cause for the climate crisis. The main contributors to global warming are manufacturing, energy, and agriculture. The agricultural sector is composed of diversified and potential mobilizable sources of waste which can become an attractive alternative to fossil fuels for energy production, and thus sequester and use carbon. Therefore, a paradigm shift towards more sustainable energy alternatives, efficient waste management, and new technologies is necessary. One good solution is the energetic valorization of lignocellulosic biomass (LCB) which can also originate from agricultural wastes. The biomass consists of cellulose, hemicellulose, and lignin, which are sources of fermentable sugars that can be used for bioethanol production. However, the recovery of sugars requires the pretreatment of LCB before enzymatic hydrolysis, due to its inaccessible molecular structure. Different pretreatment technologies, including acid and alkaline pretreatments for selected biomasses (such as hemp, rice straw, corn straw, sugarcane bagasse, and wheat straw) are discussed and compared. Therefore, this review highlights the potential of agricultural waste as a renewable resource for energy production