7 research outputs found
Etude des bobines électriques ajourées pour la réduction du rayonnement acoustique
No full textInternational audienceLes dispositifs à haute tension tels que les inductances à noyau d'air, utilisées dans le réseau de transport d’électricité, sont soumis à des normes de bruit environnemental. Leur excitation est due aux forces de Laplace provenant du champ magnétique créé par la bobine suite à son alimentation. Les composantes spectrales présentes dans le courant d’alimentation des bobines sont susceptibles de produire un rayonnement acoustique important. Afin de réduire le niveau de bruit rayonné, une conception de bobines ajourées est proposée dans ce travail. Les bobines ajourées consistent à intercaler un espace d’air entre les spires permettant de créer un court-circuit acoustique qui réduit le bruit rayonné. L’objectif de ce travail est de déterminer la configuration optimale basée sur un modèle multiphysique permettant de simuler la réponse vibroacoustique. Le modèle multiphysique présenté est le résultat du chainage de différents logiciels numériques pour le calcul électromagnétique, dynamique et vibroacoustique. Le modèle électromagnétique permet de calculer la distribution et les amplitudes des forces de Laplace appliquées sur la structure mécanique de la bobine à partir de l’alimentation d’entrée. Le modèle dynamique permet de déterminer la base modale de la bobine sur laquelle les forces de Laplace sont appliquées ainsi que le calcul des champs d’accélération de la structure sous l’effet des forces modales de Laplace. Enfin, la réponse vibroacoustique est calculée par éléments de frontière. Ce modèle est appliqué pour l’étude de différentes configurations industrielles de bobines ajourées à noyau vide. Des comparaisons entre le niveau de bruit rayonné par des bobines ajourées et non ajourées montrent une réduction considérable du bruit rayonné
Modèle multiphysique pour la prédiction du rayonnement acoustique d'une bobine électrique à noyau d'air
No full textInternational audienc
On the electronic nature of silicon and germanium based oxynitrides and their related mechanical, optical and vibrational properties as obtained from DFT and DFPT
No full textElectronic structure, bonding and optical properties of the orthorhombic oxynitrides Si 2N 2O and Ge 2N 2O are studied using the density function theory as implemented in pseudo-potential plane wave and full-potential (linearized) augmented plane wave plus local orbitals methods. Generalized gradient approximation is employed in order to determine the band gap energy. Indeed, the Si 2N 2O exhibits a large direct gap whereas Ge 2N 2O have an indirect one. Bonding is analyzed via the charge densities and Mulliken population, where the role of oxygen is investigated. The analysis of the elastic constants show the mechanical stability of both oxynitrides. Their bulk and shear modulus are slightly smaller than those reported on nitrides semiconductors due to the oxygen presence. The optical properties, namely the dielectric function, optical reflectivity, refractive index and electron energy loss, are reported for radiation up to 30 eV. The phonon dispersion relation, zone-center optical mode frequency, density of phonon states are calculated using the density functional perturbed theory. Thermodynamic properties of Si 2N 2O and Ge 2N 2O, such as heat capacity and Debye temperature, are given for reference. Our study suggests that Si 2N 2O and Ge 2N 2O could be a promising potential materials for applications in the microelectronics and optoelectronics areas of research. © 2011 Elsevier B.V. All rights reserved.A part of calculations with Wien2k code has been performed in ISCF computers of FUNDP University (Belgium) during the research stays of S. G-S and M. B. K. CASTEP calculations were carried out partially in the Beowulf class heterogeneous computer cluster at KAUST. For the author A. H. R. his work was supported from the institutional research concept of the Institute of Physical Biology, UFB (No. MSM6007665808), the program RDI of the Czech Republic, the project CENAKVA (No. CZ.1.05/2.1.00/01.0024), the grant No. 152/2010/Z of the Grant Agency of the University of South Bohemia and the School of Material Engineering, Malaysia University of Perlis
Evidence of Coulomb correction and spinorbit coupling in rare-earth dioxides CeO 2, PrO 2 and TbO 2: An ab initio study
No full textThe current study investigates the structural, elastic, electronic and optical properties of CeO 2, PrO 2 and TbO 2 using the full potential (linearized) augmented plane wave plus local orbital method within the WuCohen generalized gradient approximation (GGA) with Hubbard (U) correction and spinorbit coupling (SOC). The GGAU implementation lead us to describe correctly the relativistic effect on 4f electrons for CeO 2. We clarify that the inclusion of the Hubbard U parameter and the spinorbit coupling are responsible for the ferromagnetic insulating of PrO 2 and TbO 2. The magnetic description is achieved by the spin-density contours and magnetic moment calculations, where we show the polarization of oxygen atoms from the rare earth atoms. The mechanical stability is shown via the elastic constants calculations. The optical properties, namely the dielectric function and the reflectivity are calculated for radiation up to 12 eV, giving interesting optoelectronic properties to these dioxides. © 2011 Elsevier B.V. All rights reserved.A part of calculations with Wien2k and VASP codes have been performed in ISCF computers of FUNDP University (Belgium) during the research stays of S.G.-S. and M.B.K. VASP calculations were carried out partially in the Beowulf class heterogeneous computer cluster at KAUST. S.G.-S. and M.B.K. wish to thank Alberto Otero de la Roza from Universidad de Oviedo (Spain) for providing us with RUNWIEN code. For the author A.H.R., his work was supported from the program RDI of the Czech Republic, the project CENAKVA (No. CZ.1.05/2.1.00/01.0024), the Grant no. 152/2010/Z of the Grant Agency of the University of South Bohemia. School of Material Engineering, Malaysia University of Perlis, P.O. Box 77, d/a Pejabat Pos Besar, 01007 Kangar, Perlis, Malaysia
Multicenter prospective randomized study comparing the technique of using a bovine pericardium biological prosthesis reinforcement in parietal herniorrhaphy (Tutomesh TUTOGEN) with simple parietal herniorrhaphy, in a potentially contaminated setting
No full textThe use of parietal synthetic prosthetic reinforcement material in potentially contaminated settings is not recommended, as there is a risk that the prosthesis may become infected. Thus, simple parietal herniorrhaphy, is the conventional treatment, even though there is a significant risk that the hernia may recur. Using new biomaterials of animal origin presently appears to offer a new therapeutic solution, but their effectiveness has yet to be demonstrated. The purpose of this multicenter prospective randomized single-blind study was to compare the surgical treatment of inguinal hernia or abdominal incisional hernia by simple parietal herniorrhaphy without prosthetic reinforcement (Group A), with Tutomesh TUTOGEN biological prosthesis reinforcement parietal herniorrhaphy (Group B), in a potentially contaminated setting. We examined early postoperative complications in the first month after the operation, performed an assessment after one year of survival without recurrence and analyzed the quality of life and pain of the patients (using SF-12 health status questionnaire and Visual Analog Pain Scale) at 1, 6, and 12 months, together with an economic impact study. Hundred and thirty four patients were enrolled between January 2009 and October 2010 in 20 French hospitals. The groups were comparable with respect to their enrollment characteristics, their history, types of operative indications and procedures carried out. At one month post-op, the rate of infectious complications (n(A)?=?11(18.33%) vs. n(B)?=?12(19.05%), p?=?0.919) was not significantly different between the two groups. The assessment after one year of survival without recurrence revealed that survival was significantly greater in Group B (Group A recurrence: 10, Group B: 3; p?=?0.0475). No difference in the patients' quality of life was demonstrated at 1, 6, or 12 months. However, at the 1 month follow-up, the "perceived health" rating seemed better in the group with Tutomesh (p?=?0.022). No significant difference between the two parietal repair groups was observed during the follow-ups with respect to the criterion of pain (using a visual analog scale). There was a significant difference between the two parietal repair groups with regard to the number of days spent in intensive care unit, in favor of the Tutomesh technique (p?=?0.010). The use of a Tutomesh bioprosthesis for hernia repair or postincisional hernia in a potentially contaminated workplace reduces the risk of short-term recurrence without increasing overall comorbidity
Antifungal activity of essential oils of three aromatic plants from western Algéria against five fungal pathogens of tomato (Lycopersicon esculentum Mill)
No full textThe antifungal effect of the essential oils from Thymus capitatus L., Daucus crinitus Desf. and Tetraclinis articulate Vahl., aerial parts was evaluated in vitro against five phytopathogenic fungi of tomato (Fusarium oxysporum, Alternaria solani, Aspergillus niger, Penicillium sp1 and Penicillium sp2). Our results showed that among the three plant species tested, T. capitatus oil was the most potent antifungal against the fungi (inhibition of mycelial growth of 100 % at a concentration of 2 µg mL-1). Furthermore, the essential oil of T. articulata was also effective against F. oxysporum, A. solani, A. niger, Penicillium sp1 and Penicillium sp2 with an inhibition of mycelial growth greater than 57 % at a concentration of 5 µg mL-1. D. crinitus essential oil was less effective. T. capitatus essential oil was dominated by carvacrol (69.6 %) and p-cymene (12.4 %). The isochavicol isobutyrate (44.9 %) and isochavicol 2-methylbutyrate (9.7 %) were the major compounds in D. crinitus essential oil, while the most abundant compounds in T. articulata were α-pinene (32.0 %), cedrol (11.0 %) and 3-carene (9.6 %).The plant essential oils were found to be an effective antifungal against of mycelial growth and, therefore, can be exploited as an ideal treatment against disease rot of tomato or as a new potential source of natural additives for the food and/or pharmaceutical industries
Corylus avellana L. Husks an Underutilized Waste but a Valuable Source of Polyphenols
No full text[EN] Bioactive potential of hazelnut husks was determined as a function of their cultivar source and extraction solvent. Hazelnut husks from four hazelnut cultivars (Butler, Grada de Viseu, Lansing and Morell) were picked in a hazelnut orchard at harvest and extracted with five solvents with different polarity: water, methanol, acetone, ethyl acetate and hexane. Phenolics were identified by HPLC-DAD and antioxidant activity was determined by three complementary methods: DPPH, FRAP and inhibition of lipid peroxidation. A total of 11 phenolics were identified in studied cultivars and grouped in five main classes namely, ellagitannin (ellagic acid), benzoic acids (gallic acid, protocatechuic acid and vanillic acid), flavonols (kaempferol-3,7-O-diglucoside, kaempferol-3-O-[6-acetylglucoside]-7-O-glucoside, kaempferol-3-O-[6acetylglucoside]-7-O-rhamnoside and quercetin-3-O-rutinoside), flavone (luteolin-7-O-rutinoside) and flavan-3-ol (epicatechin). Cultivar and extraction solvent influenced significantly (p < 0.001) the extraction yield. 'Grada de Viseu' husks presented the highest content of individual phenolics identified, particularly in methanol extracts whilst 'Lansing' showed the lowest levels. Similar pattern was found for antioxidant activities. Methanolic husk extracts exhibited the greatest antioxidant potentials followed by water and acetone. The valorization of hazelnuts by-products gives an important contribution for the isolation and purification of bioactive molecules that can be used for both medicinal and industrial purposes.The author Sandra Cabo acknowledges the financial support by the Portuguese Foundation for Science and Technology (FCT) (PB/BD/113615/2015) under the Doctoral Programme "Agricultural Production Chains-from fork to farm" (PD/00122/2012). The authors also acknowledge the financial support provided by National Funds from FCT, under the project UID/AGR/04033/2019. The authors acknowledge the financial support of INTERACT project "Integrative Research in Environment, Agro-Chains and Technology", no. NORTE-01-0145-FEDER-000017, in its line of research entitled ISAC, co-financed by the European Regional Development Fund (ERDF) through NORTE 2020 (North Regional Operational Program 2014/2020) and Project IBERPHENOL, Project Number 0377_IBERPHENOL_6_E, co-financed by European Regional Development Fund (ERDF) through POCTEP 2014-2020.Cabo, S.; Aires, A.; Carvalho, R.; Pascual-Seva, N.; Silva, AP.; Gonçalves, B. (2021). Corylus avellana L. Husks an Underutilized Waste but a Valuable Source of Polyphenols. Waste and Biomass Valorization. 12(7):3629-3644. https://doi.org/10.1007/s12649-020-01246-4S36293644127Molnar, T.J., Goffreda, J.C., Funk, C.R.: Developing hazelnuts for the eastern United States. 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