Numerical modelling of a high temperature power module technology with SiC devices for high density power electronics

This paper presents the development of a new packaging technology using silicon carbide (SiC) power devices. These devices will be used in the next power electronic converters. They will provide higher densities, switching frequencies and operating temperature than current Si technologies. Thus the new designed packaging has to take into account such new constraints. The presented work tries to demonstrate the importance of packaging designs for the performance and reliability of integrated SiC power modules. In order to increase the integrated density in power modules, packaging technologies consisting of two stacked substrates with power devices and copper bumps soldered between them were proposed into two configurations. Silver sintering technique is used as die-attach material solution. In order to assess the assembling process and robustness of these packaging designs, the thermo-mechanical behaviour is studied using FEM modelling. Finally, some recommendations are made in order to choose the suitable design for reliable power module

Etude du comportement mécanique des joints de brasure Au-Ge pour le report des composants SiC pour l’électronique de puissance haute température

Ce papier contribue à l'étude de nouvelles technologies d’assemblage des puces en SiC utilisées dans les modules de puissance hautes températures (250°C). En effet, parmi tous les matériaux entrant dans l’assemblage de ces modules de puissance, le matériau de report des puces sur les substrats fait partie des matériaux les plus susceptibles aux contraintes thermomécaniques. Ainsi, pour répondre aux problématiques d'assemblage de ces puces en SiC, de nouvelles solutions de brasure doivent être développées. L’alliage de brasure Au-Ge peut être utilisé comme alliage de brasure sans plomb pour la haute température grâce à ses bonnes propriétés thermiques et mécaniques. Dans cet article, l’étude du comportement mécanique des joints formés avec la brasure Au-Ge et les puces en SiC, a été réalisée dans le but d’évaluer la robustesse et la fiabilité de ces jonctions en haute température

Towards a reliability analysis method of wide band gap power electronic components and modules

This study is addressing on the reliability of COTS (Commercial Off-The-Shelf) power electronic components and modules which could be used in high reliability systems such as aerospace systems. This paper details the first followed steps to achieve a reliability assessment of some COTS power devices. These first steps are: - Construction analyses for the determination of the packaging assembly technologies of COTS power devices; - Discussion on the material used in COTS power devices; - Synthesis of the potential failure risk analysis under harsh environments; - Determination of several accelerated ageing tests to check the potential failure modes and mechanisms in power electronic for aerospace systems

GÖÇ VE YAŞAM

Uluslararası Bakalorya Programı, A1 dersi Türk Dili ve Edebiyatı alanında ele alınan bu tezde, Orhan Kemal'in Gurbet Kuşları adlı yapıtında göç olgusu nedenleri ve sonuçlarıyla beraber incelenmiştir. Göç olgusuyla değişen toplumsal yapı, ekonomik ve kültürel farklılıklar çerçevesinde değerlendirilmiştir. Bu tezin amacı, göç olgusunun toplumsal yapıda alt sınıf ve üst sınıflardaki bireyler üzerindeki etkilerini ortaya koymaktır. Üç ana bölümden oluşan tezin ilk bölümünde yapıta adını veren Gurbet Kuşları kavramı üzerinde durulmuştur. Köylülerin aidiyetsizliği ve uyum sorunu bu bölümde aktarılmıştır. Tezin ikinci bölümünde ise köylülerin köyden kente göç sürecinde yaşadıkları kadın ve erkek figürler üzerinden neden ve sonuçlarıyla işlenmiştir. Tezin üçüncü bölümünde şehirliler başlığı altından genel olarak şehirde – İstanbul – yaşayan insanların göç sürecinde köylülerle yaşadıkları uyumsuzluk ve çatışmalara yer verilmektedir. Çalışmada göç sürecinde şehre yerleşen figürlerin şehirlilerle aralarındaki ekonomik ve kültürel farklılıkların sınıflar arasında geçişe olanak tanımadığı sonucuna varılmıştır

Study of packaging reliability of two SiC Schottky diodes of power electronic

This study deals with reliability methods developed for power electronic devices dedicated to the aerospace industry, because the reliability is a key issue for safe aerospace applications. Based on end-user requirements, eight different types of non-hermetic power electronic components in standard plastic package have been selected from the commercial marketplace, in particular Si and SiC power electronic devices. These devices are COTS (Component Off The Shelf). The main failure modes and mechanisms expected have been highlighted in specific environments in accordance with the literature. They will be presented in the final paper

Three new PAX6 mutations including one causing an unusual ophthalmic phenotype associated with neurodevelopmental abnormalities

The PAX6 gene was first described as a candidate for human aniridia. However, PAX6 expression is not restricted to the eye and it appears to be crucial for brain development. We studied PAX6 mutations in a large spectrum of patients who presented with aniridia phenotypes, Peters' anomaly, and anterior segment malformations associated or not with neurological anomalies.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Expansion of Canopy-Forming Willows Over the Twentieth Century on Herschel Island, Yukon Territory, Canada

Canopy-forming shrubs are reported to be increasing at sites around the circumpolar Arctic. Our results indicate expansion in canopy cover and height of willows on Herschel Island located at 70° north on the western Arctic coast of the Yukon Territory. We examined historic photographs, repeated vegetation surveys, and conducted monitoring of long-term plots and found evidence of increases of each of the dominant canopy-forming willow species (Salix richardsonii, Salix glauca and Salix pulchra), during the twentieth century. A simple model of patch initiation indicates that the majority of willow patches for each of these species became established between 1910 and 1960, with stem ages and maximum growth rates indicating that some patches could have established as late as the 1980s. Collectively, these results suggest that willow species are increasing in canopy cover and height on Herschel Island. We did not find evidence that expansion of willow patches is currently limited by herbivory, disease, or growing conditions. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s13280-011-0168-y) contains supplementary material, which is available to authorized users

La trousse de médication familiale aromatique

MONTPELLIER-BU Pharmacie (341722105) / SudocSudocFranceF

Experimental Approaches to Study Genome Packaging of Influenza A Viruses

International audienceThe genome of influenza A viruses (IAV) consists of eight single-stranded negative sense viral RNAs (vRNAs) encapsidated into viral ribonucleoproteins (vRNPs). It is now well established that genome packaging (i.e., the incorporation of a set of eight distinct vRNPs into budding viral particles), follows a specific pathway guided by segment-specific cis-acting packaging signals on each vRNA. However, the precise nature and function of the packaging signals, and the mechanisms underlying the assembly of vRNPs into sub-bundles in the cytoplasm and their selective packaging at the viral budding site, remain largely unknown. Here, we review the diverse and complementary methods currently being used to elucidate these aspects of the viral cycle. They range from conventional and competitive reverse genetics, single molecule imaging of vRNPs by fluorescence in situ hybridization (FISH) and high-resolution electron microscopy and tomography of budding viral particles, to solely in vitro approaches to investigate vRNA-vRNA interactions at the molecular level

Microwave signatures over carbonate sedimentary platforms in arid areas: potential geological applications of passive microwave observations?

4International audienceMicrowave emissivities have been calculated over the globe from satellite observation between 19 and 85 GHz with the special sensor Microwave/imager SSM