Parasitic elements modeling and experimental identification in a gan hemt based power module

International audienceIn this paper, the parasitic elements of a GaN based power module are investigated. Because the very high-speed switching of GaN high electron mobility transistors leads to overvoltage, conducted and radiated emissions, it is crucial to manage accurately the routing of the power module in order to minimize parasitic capacitances and inductances. The paper focuses on the prediction of these parasitic effects and their comparisons to measurements. In this approach, the difficulty lies in the determination of very small values of the parasitic elements which requires specific operating for calibration and measurements

Black box EMC modeling of a three phase inverter

International audienceThis paper presents an Electromagnetic Interferences (EMI) modeling of a DC-AC power converter, based on a black box representation: the converter is represented by an association of sources and impedances that reflect its external EMI behavior. This modeling approach presented in this paper requires a very short computation time, which allows an optimized design of an EMC filter or an interaction study between several converters connected on the same electrical network. This EMC model depending on a given operation point of the converter, the second part of this paper is dedicated to the study of the load influence on this behavioral model

Полупроводниковый генераторный модуль с умножением частоты для аппаратуры КВЧ-терапии

С целью расширения диапазона частот и получения высококогерентного электромагнитного излучения предложено осуществлять умножение частоты исходного сигнала

Crossroad between Inflammation, Iron and Lipids in Atherogenesis

Atherosclerosis (ATH) is recognized as a chronic inflammatory condition and it is the leading cause of cardiovascular disease. The process of atherogenesis is characterized by the accumulation and oxidation of LDL (oxLDL) in the vessel wall and subsequent infiltration and activation of immune cells, particularly monocytes in an earlier stage and, later on, lymphocytes. The infiltrated monocytes differentiate into macrophages which then could differentiate into foam cells as a consequence of oxLDL uptake [1]. The recruitment of immune cells to the site of ATH lesion contributes to a local pro-inflammatory state that will promote the development of the atheroma plaque and progression of the disease. However, the exact mechanisms involved in this process are not fully understood. One hypothesis is the contribution of oxidative stress mediated by metals such as iron [2]. Previous authors have shown high iron content in foam cells and also accumulation of hemoglobin and ferritin in the areas rich in foam cells [3]. Herein, we investigate a possible mechanism for cellular iron accumulation by testing the effect of pro-inflammatory as well as pro-atherogenic stimuli in the expression of proteins involved in iron efflux in macrophages.This work was supported by National Institute of Health Doutor Ricardo Jorge, I.P, INSERM (Institut National de la Santé et de la Recherche Médicale), CNRS (Centre National de la Recherche Scientifique), ANR (Agence Nationale de la Recherche, France; ANR- 08- GENO-000) , Fundação para a Ciência e Tecnologia (Grant SFRH/BD/48671/2008) and BioFIG (Center for Biodiversity, Functional and Integrative Genomics)

Identification of zones of preferential groundwater tracer transport using a mobile downhole fluorometer

A mobile downhole fluorometer was used to detect zones of preferential groundwater tracer transport into an observation well. Identification of such zones is not possible if individual samples are collected over the well's entire screened interval. Laboratory-based tests using the fluorometer, and a purpose-built apparatus demonstrated that the fluorometer could be used with tracers to characterise well water flow regimes. During field investigations in a porous aquifer, the fluorometer monitored tracer concentrations in an observation well with a 12-m-long screen, 10m down the hydraulic gradient from a fully penetrating injection well. Test results showed that the tracer occurred in the observation well over a discrete 2.5-m-thick interval. Single-well dilution test and vertical-flow data indicated that water entered the well at additional depths, but no tracer was detected at these levels. A numerical model reproducing dilution test concentration profiles indicated that water entered the well in many of these horizons at comparable velocities to those in the tracer-bearing zone. These data suggest that groundwater flow direction varied with depth in the aquifer under investigation. Moreover, simulations of tracer arrival indicated that the tracer distribution observed in the observation well was derived from a horizon that may be no thicker than 0.5

Early disturbances of gamma band dynamics in mild cognitive impairment

Recent studies have indicated that gamma band oscillations participate in the temporal binding needed for the synchronization of cortical networks involved in short-term memory and attentional processes. To date, no study has explored the temporal dynamics of gamma band in the early stages of dementia. At baseline, gamma band analysis was performed in 29 cases with mild cognitive impairment (MCI) during the n-back task. Based on phase diagrams, multiple linear regression models were built to explore the relationship between the cognitive status and gamma oscillation changes over time. Individual measures of phase diagram complexity were made using fractal dimension values. After 1year, all cases were assessed neuropsychologically using the same battery. A total of 16 MCI patients showed progressive cognitive decline (PMCI) and 13 remained stable (SMCI). When adjusted for gamma values at lag −2, and −3ms, PMCI cases displayed significantly lower average changes in gamma values than SMCI cases both in detection and 2-back tasks. Gamma fractal dimension of PMCI cases displayed significantly higher gamma fractal dimension values compared to SMCI cases. This variable explained 11.8% of the cognitive variability in this series. Our data indicate that the progression of cognitive decline in MCI is associated with early deficits in temporal binding that occur during the activation of selective attention processe

Traitement des appels d'urgence sur le réseau routier en Europe : rapport de synthèse

Dans le cadre de son étude sur les évolutions du traitement des appels d'urgence et la place des Réseaux d'Appel d'Urgence le CERTU a confié à la Société LOGMA l'étude de la situation dans quatre pays européens (Allemagne, Grande-Bretagne, Hollande et Italie) . Ce rapport en est la synthèse ; il comprend : > Une présentation générale. â La synthèse des informations obtenues pour les pays étudiés. L'étude de l'organisation des services privés d'assistance (automobiles-clubs). L'étude des appels d'urgence sur les réseaux autoroutiers concédés et autres réseaux. L'étude des appels d'urgence par téléphonie mobile. La présentation des études, expérimentations et recherches en cours dans les différents domaines. La synthèse des éléments relatifs à l'Europe