Electrical Distribution Busbars Modeling:Extension of the PEEC Method for LF Ferromagnetic Shieldings

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Introducing Linear Magnetic Materials in PEEC Simulations. Principles, Academic and Industrial Applications

International audienceIn order to study impact of wiring impedances PEEC simulation method has proved to be reliable, fast, and applicable to a wide range of practical problems. However, up till now, this method is inapplicable when a piece of magnetic material is located close to one of the studied wire. In this paper we present a method that overcomes this limitation with a very little cost in computing time. Owing to it, magnetic materials can be introduced, assuming only their behavior is linear. They can be conductive or not and their permeability can be complex to account for magnetic losses. Principles of the extension are carefully established and some academic problems are solved to compare with both analytical formulation and results of FEM simulation software. To end, an industrial problem is solved to illustrate the practical interest of this extension

A global approach dedicated to EMC and energy efficiency

International audienceIn order to provide a "multi-scale" design of the power electrical systems, two kinds of devices are identified: (i) those dedicated to power conversion; and their (ii) couplings. While the finite element method appears to be the natural design tool in the former, the so-called PEEC method is the more suitable in the latter. All devices should achieve EMC and design should be sought within the life cycle assessment framework to take network management considerations into accoun

PEEC Method Dedicated to Power Busbar Design

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Observations on the oxygen consumption during maturation of wines on lees

Traditional enological practices (« Bâtonnage » or « microoxygénation » techniques) during wine aging on yeast lees include limited repetitive additions of small amounts of oxygen to the wines. Such empirical practices are generally associated with a limited homogenisation of wine and lees. In this study, the potential relationship between oxygen consumption and the presence of wine lees during wine aging was investigated. Strong oxygen uptake rates by yeast lees were observed during wine aging at 14°C on total yeast lees obtained after fermentation of either synthetic medium or red and white grape musts. These specific oxygen utilization rates by yeast lees is always comprised between 3 and 11 μg O2 h-1 10-9 cells from the second to the sixth month of aging. The initial levels of specific oxygen utilization rates and the time-decay of these rates along wine aging were very dependent on yeast strains. However such oxygen utilization rates by yeast lees could be responsible for the total dissolved oxygen depletion from wines in less than 20 hours at 14°C during aging on total lees. Such results were of particular importance to evaluate the exact timing of oxygen additions during wine aging on lees. Further experiments had to be done to determine the biological or chemical nature of such oxygen consumption by lees. Such oxygen consumption by yeast lees may lead to final reaction products which may exert strong organoleptic effects on the final quality of wines

Qualitative and semi-quantitative analysis of phenolics in Eucalyptus globulus leaves by high-performance liquid chromatography coupled with diode array detection and electrospray ionisation mass spectrometry

Introduction - Eucalyptus species are widely cultivated in Mediterranean regions. Moreover, plants of this family have been utilized for medicinal purposes. A number of studies have been devoted to the identification of eucalypt phenolics, all of them have focused on specific families of compounds, and no exhaustive profiling has been reported in leaves of this plant. Objective - To develop methods that allows the identification and quantification of different classes of phenolics in Eucalyptus globulus leaf. Methodology - Acetonic extract was fractionated by chromatography on a Sephadex LH-20 column using consecutive elution with ethanol, methanol and aqueous acetone (60%). High-performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry (HPLC-DAD-ESI/MS) were applied to determine the structure of different compounds. Quantities were evaluated from peak areas in the HPLC profile, using external calibration curves. Results - Fractionation of acetonic extract yielded three fractions: F1, F2 and F3. In total 39 phenolic compounds are detected. Among them: 16 hydrolyzable tannins, 3 terpenyl derivatives, 12 ellagic acid derivatives, 5 flavonols, 2 hydroxybenzoic acids and 1 formylated phloroglucinol. 26 compounds described in this study have not previously detected in leaves of this plant and this is the first report of quercetin 3-O-beta-galactoside-6 ''-O-gallate and cypellogin A and B, in E. globulus plant. Quantitatively, ellagic acid derivatives and sideroxylonal A or B are largely predominant. Conclusion - Fractionation of crude extract by chromatography on Sephadex LH-20 was efficient to separate different molecular weight compounds. HPLC-DAD-ESI/MS enabled detection of gallotannin, ellagitannin and flavonol derivatives, in leaves of E. globulus

Table ronde - Conclusion

En introduction aux interventions des participants et aux débats Jean-Paul Bertaud suggère quatre questions de nature à susciter la réflexion sur le thème proposé. La première porte sur le fait de savoir si la dictature de l'homme en armes était ou non irrésistible, comme le croyait déjà Robespierre ou comme l'a exposé Georges Lefebvre, qui nous a habitués à voir dans la prise de pouvoir de Bonaparte la suite de l’histoire de la Révolution, dès lors qu'elle devient une Révolution armée. Dans ..

Toward a global approach dedicated to electromagnetic compatibility and energy efficiency

International audienceThe local laws of electromagnetism are derived from the optimization of the global mechanical power exchanged throughout the electrical network. Two kinds of devices are identified: (i) those dedicated to power conversion; and their (ii) couplings involved in transmission lines, distribution busways, cablings and connections. While the finite element method appears to be the natural design tool in the former, the so-called PEEC method is the more suitable in the latter. Its recent improvements are reviewed within the low-frequency framework including (i) back emf of ferromagnetic materials (shielding); (ii) optimization methods to reduce Joule losses or flux density levels; and (iii) integration into a CAE package

The hidden face of food phenolic composition

Plant polyphenols are extremely diverse, due to the occurrence of several basic structures, numerous substitutions and, for some groups, of polymers (tannins). Plant polyphenol composition depends on the plant species and organ, with some molecules specific of particular plant families while others are ubiquitous. The polyphenol content is classically assessed by global analysis methods, which lack specificity and accuracy. These methods have been replaced with high performance liquid chromatography (HPLC), that enables accurate determination of individual molecules, provided they can be unambiguously identified and calibration curves can be established. However, HPLC analysis is restricted to simple compounds and difficult to apply in the case of complex extracts. Further difficulties encountered in the case of polymers include irreversible adsorption on the stationary phases. Proanthocyanidin analysis by HPLC after acid-catalysed depolymerisation in the presence of a nucleophile permits to overcome these problems and shows that proanthocyanidins predominate in the polyphenol composition of most plants. Large varietal differences in tannin quantitative and qualitative composition were observed for all plant species studied. Moreover, analysis is usually performed after extraction, which may lead to significant underestimation of the polyphenol content, since a large proportion is not extracted by usual solvents. This may be due to covalent binding to other plant constituents and to non-covalent adsorption on plant solids. Such matrix effect also influences the taste perception of polyphenols and their fate in the digestive tract, from in-mouth interactions with salivary proteins to their metabolism by colon microflora, with potential influence on bioavailability