Numerical investigation of heat transfer enhancement inside a parabolic trough solar collector using dimpled absorber

Three dimensional numerical investigation of heat transfer enhancement in a non-uniformly heated parabolic trough solar collector using dimpled absorber under turbulent flow was incorporated in the current paper. The governing equations were solved using the finite volume methods (CFD) with certain assumptions and appropriate boundary conditions. The Monte Carlo ray trace technique was applied to obtain the heat flux distribution around the absorber tube. The numerical results were validating with the empirical correlations existing in the literature and good agreement was obtained. The present results demonstrate that the inclusion of inserts provide a good performance in heat transfer,   also the receiver temperature gradient are shown to reduce with the use of geometrical modification, the absorber geometry have a remarkable effect on the HTF velocity distribution

Biomedical Knowledge Extraction Using Fuzzy Differential Profiles and Semantic Ranking

International audienceRecently, technologies such as DNA microarrays allow to generate big scale of transcriptomic data used to the aim of exploring background of genes. The analysis and the interpretation of such data requires important databases and efficient mining methods, in order to extract specific biological functions belonging to a group of genes of an expression profile. To this aim, we propose here a new approach for mining transcriptomic data combining domain knowledge and classification methods. Firstly, we propose the definition of Fuzzy Differential Gene Expression Profiles (FG-DEP) based on fuzzy classification and a differential definition between the considered biological situations. Secondly, we will use our previously defined efficient semantic similarity measure (called IntelliGO), that is applied on Gene Ontology (GO) annotation terms, for computing semantic and functional similarities between genes of resulting FG-DEP and well known genetic markers involved in the development of cancers. After that, the similarity matrices will be used to introduce a novel Functional Spectral Representation (FSR) calculated through a semantic ranking of genes regarding their similarities with the tumoral markers. The FSR representation should help expert to interpret by a new way transcriptomic data and infer new genes having similar biological functions regarding well known diseases

Formal Concept Analysis and Knowledge Integration for Highlighting Statistically Enriched Functions from Microarrays Data

International audienceIn this paper we introduce a new method for extracting enriched biological functions from transcriptomic databases using an integrative bi-classication approach. The initial gene datasets are firstly represented as a formal context (objects attributes), where objects are genes, and attributes are their expression profiles and complementary information of different knowledge bases. After that, Formal Concept Analysis (FCA) is applied for extracting formal concepts regrouping genes having similar transcriptomic profiles and functional behaviors. An enrichment analysis is then performed in order to identify the pertinent formal concepts from the generated Galois lattice, and to extract biological functions that could participate in the proliferation of cancers

Etude des mécanismes de transport dans les diodes tunnels de type MIS associant ferromagnétiques et silicium

The study of fundamental mechanisms which control the injection of spins from a ferromagnetic metal to silicon is the subject of this work of thesis. This study is based on the modelling and analysis of electrical characteristics of a test structure composed of two ferromagnetic electrodes used respectively to inject and collect spins. The study of electrical properties of a FMIS diode (ferromagnet/isolant/silicon) is realised. The selective inversion of the orientation of the magnetization of one of the electrodes and the variation of the magneto resistance is a signature of spin injection into silicon. This concept of magnetic memory integrated on silicon can give an alternative solution to other memories like the flash one which have many problems.L'étude des mécanismes fondamentaux qui contrôlent l'injection des électrons polarisés en spin à partir d'un métal ferromagnétique vers le silicium ainsi que l'interaction entre ces spins et l'aimantation d'une électrode ferromagnétique « collectrice » en spin, constitue le sujet de ce travail de thèse. Cette étude est basée sur l'analyse et la modélisation des caractéristiques électriques obtenues sur une structure « test » composée de deux électrodes ferromagnétiques servant respectivement à injecter et à collecter les électrons polarisés en spin. Une étude approfondie des propriétés électriques de la diode ferromagnétique/isolant/silicium (FMIS) est aussi réalisée. Le renversement sélectif de l'aimantation d'une des deux électrodes et la variation de la (magnéto-) résistance attendue fournissent un outil pour l'étude de l'injection de spins dans le silicium. Ce concept de mémoire magnétique intégrée sur silicium pourrait fournir à terme une solution alternative aux mémoires de type flash qui vont être de plus en plus confrontées au problème de rétention d'information

Measurement of the K0 inclusive cross section in pion-induced reactions at 1.15 GeV/c

Der Wirkungsquerschnitt der K0-Produktion und dessen Phasenraumverteilungen wurden in Pion-Kern-Reaktionen bei einem Pion-Impuls von 1.15 GeV/c für C-, Al-, Cu-,Sn- und Pb-Kerne untersucht. Die Abhängigkeit des K0-Produktionswirkungsquerschnitts von der Systemgröße A wurde zum ersten Mal gemessen und eine A^2/3-Abängigkeit wurde beobachtet. Das experimentell bestimmte Verhältnis der K0-Impulsverteilungen in Blei zu denen in Kohlenstoff ist für niedrige Impulse stark unterdrückt. Ein Vergleich mit dem entsprechenden Verhältnis für K+ aus Proton-Kern-Reaktionen zeigt eine gute Übereinstimmung, daher ist diese Observable geeignet zur Untersuchung des KN-Potentials. Vergleiche mit Berechnungen des HSD-Transportmodells verdeutlichen, dass dieses Modell bisher noch nicht in der Lage ist, Impuls- und Rapiditätsverteilungen des K0, sowie die Abhängigkeit der inklusiven K0-Produktion von der Systemgröße zu beschreiben. Berechnungen des K0-Produktionswirkungsquerschnitts im Rahmen eines mikroskopischen Modells, welches ein KN-Potential für die Wechselwirkungen in Endzustand beeinhaltet, stimmen gut mit den Messergebnissen überein

Investigation of Indium Oxide Effect on Indium Particles Properties Used as Silicon Nanowires Catalyst

In this chapter, we investigate on indium particles elaboration by different annealing processes: rapid thermal annealing (RTA) and conventional processes. The elaborated particles are dedicated to be used as catalyst for silicon nanowires’ (SiNWs) growth by vapor–liquid–solid (VLS) process. The annealing parameters effect on indium particles properties is studied. After conventional annealing, the indium layer is cracked into elongated and inhomogeneous islands of micrometric sizes. XRD analysis depicts, in addition to pure indium planes, the presence of new peaks attributed to indium oxide (In2O3) planes formed during annealing. After hydrogen treatment with a flow rate of 60 sccm during 10 min, some In2O3 peaks are eliminated and replaced by new indium peaks, explaining the amelioration of indium particles morphology. These formed particles have been used as catalyst for SiNWs’ growth. A low density of SiNWs is obtained, attributed to In2O3 persistence, decreasing the indium catalytic effect. Quasi-spherical and homogeneously distributed indium particles with an average size of 422 nm are successfully grown in one step by the RTA process during short time (5 min) at lower temperature (450°C). XRD analysis shows the absence of indium oxide in the contrary to those formed by the conventional furnace. SiNWs with higher density are obtained, highlighting the harmful role of indium oxide