447 research outputs found
Naissance dâune bibliothĂšque thĂ©matique multilingue : le cas de la bibliothĂšque du Centre National de la MĂ©moire ArmĂ©nienne
Rapport de stage du Master 2 SIB, sciences de lâinformation et des bibliothĂšques, option SDN "services documentaires numĂ©riques" portant sur la bibliothĂšque multilingue de la Maison de la Culture ArmĂ©nienne de DĂ©cines, de sa normalisation et de son informatisation en vue de son intĂ©gration au Centre National de la MĂ©moire ArmĂ©nienne
Lifespan Modeling of Insulation Materials for Low Voltage Machines: films and twisted pairs
This paper deals with the modeling of insulation material lifespan in a partial discharge regime. Accelerated aging tests are carried out to determine the lifespan of polyesterimide insulation films under different various stress conditions. The insulation lifespan logarithm is modeled as a function of different factors: the electrical stress logarithms and of an exponential form of the temperature. The model parameters, or so-called factor effects, is estimated on a training set. The significance of the factors is evaluated through the analysis of variance (ANOVA). In a first step, the design of experiment method (DoE) is considered. The associated lifespan model is linear with respect to the factors. This method is well-known for reducing the number of experiments while providing a good accuracy. In a second step, the response surface method (RSm) is considered. This method takes also into account some second order terms and thus possible interactions between the stress factors. Performance of the two methods are analyzed and compared on a test set. </p
Variable Importance Assessment in Lifespan Models of Insulation Materials: A Comparative Study
International audienceThis paper presents and compares different methods for evaluating the relative importance of variables involved in insulation lifespan models. Parametric and non-parametric models are derived from accelerated aging tests on twisted pairs covered with an insulating varnish under different stress constraints (voltage, frequency and temperature). Parametric models establish a simple stress-lifespan relationship and the variable importance can be evaluated from the estimated parameters. As an alternative approach, non-parametric models explain the stress-lifespan relationship by means of regression trees or random forests (RF) for instance. Regression trees naturally provide a hierarchy between the variables. However, they suffer from a high dependency with respect to the training set. We show that RF provide a more robust model while allowing a quantitative variable importance assessment. Comparisons of the different models are performed on different training and test sets obtained through experiments
Current-Based Detection of Mechanical Unbalance in an Induction Machine Using Spectral Kurtosis with Reference
This article explores the design, on-line, of an electrical machineâs healthy reference by means of statistical tools. The deïŹnition of a healthy reference enables the computation of normalized fault indicators whose value is independent of the systemâs characteristics. This is a great advantage when diagnosing a broad range of systems with different power, coupling, inertia, load, etc. In this paper, an original method called spectral kurtosis with reference is presented in order to designa systemâs healthy reference. Its principle is ïŹrst explained on asynthetic signal. This approach is then evaluated for mechanicalunbalance detection in an induction machine using the stator currents instantaneous frequency. The normalized behaviour ofthe proposed indicator is then conïŹrmed for different operatingconditions and its robustness with respect to load variationsis demonstrated. Finally, the advantages of using a statisticalindicator based on a healthy reference compared to a raw faultsignature are discussed
Health-related quality of life among children with Turner syndrome: controlled cross-sectional study
International audienceBACKGROUND : The aim of the study was to assess health-related quality of life (HR-QoL) in children with Turner syndrome in comparison with controls.METHODS : We prospectively recruited 16 female girls with Turner syndrome (mean age 15.2±2.6 years) and 78 female controls (mean age 12.7±2.8 years) in randomly selected schools. We used the PedsQL, a generic HR-QoL questionnaire (self and parents' versions).RESULTS : Global HR-QoL scores in Turner syndrome were lower than controls for self-reports (respectively, 74.3±3.0 vs. 82.8±1.3, p=0.01) and parents' reports (62.7±3.8 vs. 80.1±1.7, p<0.0001). In Turner syndrome, self-reported HR-QoL was impaired in school functioning (70.6±4.0 vs. 80.71±1.7, p=0.02), social functioning (78.2±4.0 vs. 90.4±1.8, p<0.01) and physical functioning (78.5±3.2 vs. 87.1±1.4, p=0.02), but not in emotional functioning. Parents' reported HR-QoL was impaired in all four dimensions.CONCLUSIONS : HR-QoL was impaired in this cohort of young females with Turner syndrome, as in previously reported adult studies. In addition to medical treatment and routine clinical follow-up, female girls and teenagers with Turner syndrome should also be supported psychologically by social, educational and psychotherapeutic interventions that aim to address their self-esteem and emotional difficulties
Lifespan Modeling of Low Voltage Machines Insulation Materials
This paper deals with the modeling of insulation material lifespan in a partial discharge regime. Accelerated aging tests are carried out to determine the lifespan of polyester-imide insulation films under different various stress conditions. The insulation lifespan logarithm is modeled as a function of different factors: the electrical and frequency stress logarithms and an exponential form of the temperature. The model parameters are estimated on a training set. The significance of the factors is evaluated through the analysis of variance (ANOVA). In a first step, the design of experiments method (DoE) is considered. The associated lifespan model is linear with respect to the factors. This method is well known for reducing the number of experiments while providing a good accuracy. In a second step, the response surface method (RSM) is considered. This method takes also into account some second order terms and thus possible interactions between the stress factors. Performance of the two methods are analyzed and compared on a test set
Implementation of agronomical and geochemical modules into a 3D groundwater code for assessing nitrate storage and transport through unconfined Chalk aquifer
International audienceChalk aquifer is the main water resource for domestic water supply in many parts in northern France. In same basin, groundwater is frequently affected by quality problems concerning nitrates. Often close to or above the drinking water standards, nitrate concentration in groundwater is mainly due to historical agriculture practices, combined with leakage and aquifer recharge through the vadose zone. The complexity of processes occurring into such an environment leads to take into account a lot of knowledge on agronomy, geochemistry and hydrogeology in order to understand, model and predict the spatiotemporal evolution of nitrate content and provide a decision support tool for the water producers and stakeholders. To succeed in this challenge, conceptual and numerical models representing accurately the Chalk aquifer specificity need to be developed. A multidisciplinary approach is developed to simulate storage and transport from the ground surface until groundwater. This involves a new agronomic module " NITRATE " (NItrogen TRansfer for Arable soil to groundwaTEr), a soil-crop model allowing to calculate nitrogen mass balance in arable soil, and the " PHREEQC " numerical code for geochemical calculations, both coupled with the 3D transient groundwater numerical code " MARTHE ". Otherwise, new development achieved on MARTHE code allows the use of dual porosity and permeability calculations needed in the fissured Chalk aquifer context. This method concerning the integration of existing multidisciplinary tools is a real challenge to reduce the number of parameters by selecting the relevant equations and simplifying the equations without altering the signal. The robustness and the validity of these numerical developments are tested step by step with several simulations constrained by climate forcing, land use and nitrogen inputs over several decades. In the first time, simulations are performed in a 1D vertical unsaturated soil column for representing experimental nitrates vertical soil profiles (0-30m depth experimental measurements in Somme region). In the second time, this approach is used to simulate with a 3D model a drinking water catchment area in order to compared nitrate contents time series calculated and measured in the domestic water pumping well since 1995 (field in northern France â Avre Basin region). This numerical tool will help the decision-making in all activities in relation with water uses
Multidisciplinary subsurface monitoring for a better understanding of Soil Aquifer Treatment capacity applied on coastal operational wastewater treatment plant (Agon-Coutainville, France)
International audienceUnconfined coastal aquifers are potentially subject to both saline intrusion near the seashore and over discharge of treated wastewater in the surficial environment during the tourist season. In Agon-Coutainville (Normandy, France), managed aquifer recharge (MAR) system, combined with Soil Aquifer Treatment (SAT), was integrated as part of the full-scale operational wastewater treatment plant. Such integrated natural/engineered water treatment system ensure the sustainability of the seaside activities (seafood production, beach) and locally supply freshwater for the irrigational needs of the golf course. Concerning the MAR system, the secondary treated wastewater is infiltrated alternatively into three natural reed bed areas before reaching the sand dune aquifer and thus to enhance the quantity of freshwater in the aquifer. Treated wastewater potentially contains various compounds (chemical, virus, pathogen) which can, however, affect the groundwater quality. Nevertheless, some of these compounds are partly removed, during the SAT. To assess performance and efficiency of the integrated system in the natural environment, we have designed and performed an innovating and multidisciplinary monitoring dedicated to 1) spatial evolution of the freshwater generating by the MAR system, 2) mean residence time of water during SAT and 3) potential reactivity occurring during SAT. Spatial field campaigns and tracer tests were conducted by associating classical and innovative approaches including physico-chemical measurements and quantitative analyses, non target analysis for screening organic compounds, ecotoxicological bioassays, online biomonitoring BACTcontrolÂź system to detect fecal contamination and online system monitoring device dedicated to saline intrusion. Results show that the MAR system provides a freshwater barrier in the aquifer which is seasonally affected by saline intrusion. A part of the aquifer is assessed for freshwater potential production regardless of the natural and anthropogenic recharge. SAT mean residence time is around two weeks that allows SAT reactivity and thus increases quality of the pumped groundwater. This novel subsurface monitoring provides a better understanding of the SAT capacity to enhance the quantity of freshwater and improve its quality
Correction: Human and Drosophila Cryptochromes Are Light Activated by Flavin Photoreduction in Living Cells
Cryptochromes are a class of flavoprotein blue-light signaling receptors found in plants, animals, and humans that control plant development and the entrainment of circadian rhythms. In plant cryptochromes, light activation is proposed to result from photoreduction of a protein-bound flavin chromophore through intramolecular electron transfer. However, although similar in structure to plant cryptochromes, the light-response mechanism of animal cryptochromes remains entirely unknown. To complicate matters further, there is currently a debate on whether mammalian cryptochromes respond to light at all or are instead activated by nonâlight-dependent mechanisms. To resolve these questions, we have expressed both human and Drosophila cryptochrome proteins to high levels in living Sf21 insect cells using a baculovirus-derived expression system. Intact cells are irradiated with blue light, and the resulting cryptochrome photoconversion is monitored by fluorescence and electron paramagnetic resonance spectroscopic techniques. We demonstrate that light induces a change in the redox state of flavin bound to the receptor in both human and Drosophila cryptochromes. Photoreduction from oxidized flavin and subsequent accumulation of a semiquinone intermediate signaling state occurs by a conserved mechanism that has been previously identified for plant cryptochromes. These results provide the first evidence of how animal-type cryptochromes are activated by light in living cells. Furthermore, human cryptochrome is also shown to undergo this light response. Therefore, human cryptochromes in exposed peripheral and/or visual tissues may have novel light-sensing roles that remain to be elucidated
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