2 résultat(s) recherche sur le tag 'mobility'    

"Spéciation du Phosphore dans des Sédiments Aquatiques Optimisation Analytique Application Environnementale" / Sarah Azzouz  

Public ISBD Titre : "Spéciation du Phosphore dans des Sédiments Aquatiques Optimisation Analytique Application Environnementale" Type de document : texte imprimé Auteurs : Sarah Azzouz, Auteur ; Chahrazed Boukhalfa, Directeur de thèse Editeur : constantine [Algérie] : Université Constantine 1 Année de publication : 2014 Importance : 132 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles Langues : Français (fre) Tags : phosphore  sédiment  spéciation  adsorption  mobilité  Rhumel  Boumerzoug  El-kebir phosphorus  sediment  speciation  mobility  El-kebir Index. décimale : 540 Chimie et sciences connexes Résumé : "In this study, sediments samples were collected at three oueds in the north-east Algeria: oued El-Kebir, oued Boumerzoug and oued Rhumel. The mineralogical composition of the sediments was evaluated by X-ray fluorescence and Infrared analysis. The contents of metals Al, Ca, Fe, Mn, organic matter and total phosphorus were determined. Generally, the studied sediments are characterized by an alkaline pH, a high electrical conductivity and significant contents of organic matter. The X-ray fluorescence shows that the main components of the sediment matrix are calcium in major part, iron, silicon and aluminum. The infrared spectra show the presence of carbonates, goethite and Kaolinite. The evaluation of the phosphorus retention in the sediments of the three oueds was assessed by fractionation and adsorption tests. The obtained results show that phosphorus is mainly in inorganic form with prevalence of calcic fraction. The phosphorus retention depends on the samples composition. The sediments of oued El-Kebir retain more phosphorus than those of oued Boumerzoug and Rhumel. In a relation with the sediments composition and the method of phosphorus determination, a phosphorus extraction scheme is proposed in this study by optimizing the used reagents and the operating conditions. By applying this extraction scheme, the spatiotemporal evolution of phosphorus speciation during the year 2012, was studied in the sediments of the rivers which cross Constantine city: oued Rhumel and its tributary Boumerzoug. In the sediments of the two streams, the results show the predominance of the residual fraction and the importance of phosphorus bound to detrital apatite. The evolution of the exchangeable fraction and that related to authigenic apatite depends on the pH of the sediments. The reducible fraction is characterized by a significant spatiotemporal evolution. At the end of the summer period, the contribution of the residual organic fraction is less significant. Spatiotemporal changes in the distribution and the mobility of phosphorus are recorded in the sediments of oued Rhumel. In those of oued Boumerzoug, phosphorus is more mobile in the winter and spring." Diplôme : Doctorat En ligne : ../theses/chimie/AZZ6500.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9614 "Spéciation du Phosphore dans des Sédiments Aquatiques Optimisation Analytique Application Environnementale" [texte imprimé] / Sarah Azzouz, Auteur ; Chahrazed Boukhalfa, Directeur de thèse . - constantine (Route ain el bey, Algérie) : Université Constantine 1, 2014 . - 132 f. ; 30 cm. 2 copies imprimées disponibles Langues : Français (fre) Tags : phosphore  sédiment  spéciation  adsorption  mobilité  Rhumel  Boumerzoug  El-kebir phosphorus  sediment  speciation  mobility  El-kebir Index. décimale : 540 Chimie et sciences connexes Résumé : "In this study, sediments samples were collected at three oueds in the north-east Algeria: oued El-Kebir, oued Boumerzoug and oued Rhumel. The mineralogical composition of the sediments was evaluated by X-ray fluorescence and Infrared analysis. The contents of metals Al, Ca, Fe, Mn, organic matter and total phosphorus were determined. Generally, the studied sediments are characterized by an alkaline pH, a high electrical conductivity and significant contents of organic matter. The X-ray fluorescence shows that the main components of the sediment matrix are calcium in major part, iron, silicon and aluminum. The infrared spectra show the presence of carbonates, goethite and Kaolinite. The evaluation of the phosphorus retention in the sediments of the three oueds was assessed by fractionation and adsorption tests. The obtained results show that phosphorus is mainly in inorganic form with prevalence of calcic fraction. The phosphorus retention depends on the samples composition. The sediments of oued El-Kebir retain more phosphorus than those of oued Boumerzoug and Rhumel. In a relation with the sediments composition and the method of phosphorus determination, a phosphorus extraction scheme is proposed in this study by optimizing the used reagents and the operating conditions. By applying this extraction scheme, the spatiotemporal evolution of phosphorus speciation during the year 2012, was studied in the sediments of the rivers which cross Constantine city: oued Rhumel and its tributary Boumerzoug. In the sediments of the two streams, the results show the predominance of the residual fraction and the importance of phosphorus bound to detrital apatite. The evolution of the exchangeable fraction and that related to authigenic apatite depends on the pH of the sediments. The reducible fraction is characterized by a significant spatiotemporal evolution. At the end of the summer period, the contribution of the residual organic fraction is less significant. Spatiotemporal changes in the distribution and the mobility of phosphorus are recorded in the sediments of oued Rhumel. In those of oued Boumerzoug, phosphorus is more mobile in the winter and spring." Diplôme : Doctorat En ligne : ../theses/chimie/AZZ6500.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=9614

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Contribution à l’étude du transport électrique à travers des oxydes très minces (<10nm) dans des structures MOS / Rachida Bensegueni  

Public ISBD Titre : Contribution à l’étude du transport électrique à travers des oxydes très minces (<10nm) dans des structures MOS Type de document : texte imprimé Auteurs : Rachida Bensegueni, Auteur ; Saida Latreche, Directeur de thèse Année de publication : 2016 Importance : 166 f. Format : 30 cm. Note générale : 2 copies imprimées disponibles Langues : Français (fre) Tags : Microelectronic  down-scaling  strained Si channel  high-k dielectric  mobility  gate leakage currents  direct tunneling current  Microélectronique  miniaturisation  MOSFET  Silicium contraint  diélectrique haute permittivité  mobilité  courants de fuites  courant tunnel direct  ???????????? ???????? ???????  ????????? ???????? ?????? ??????  ?????? ???? ????????  ?????? ??????????  ????????  ???? ????? Index. décimale : 621 Electronique Résumé : The continuous down-scaling of MOS transistors dimensions over the last years allowed a significant revolution in the semiconductor industry. However, in order to maintain this trend, shrinking of conventional n MOS dimensions is no more sufficient enough and replacement of some transistor materials is one of the alternative ways currently under study to solve this issue. In this context, the work presented here, on the study of the transport properties of the nMOS architectures combining both new technology options; a high-k gate dielectric in place of the SiO2 and a biaxialy tensile strained channel. Firstly, the influence of biaxial tensile strain on the electrical properties of the n-MOS transistor has been investigated using a numerical solution of drift diffusion partial equations. The simulation results showed a significant improvement in electrons mobility and an increase in current ID (VD). Then, we study the impact of the incorporation of a high-k gate stack on improving leakage through the oxide. The calculation results obtained from the ATLAS (SILVACOTCAD) simulator have shown that the use of high dielectric constant oxides significantly reduces the tunneling leakage current through increased physical thickness of the stack. However, we noted a decrease of the electron mobility in the channel If MOS transistors with a high-k dielectric HfO2 hafnium relative to SiO2 Finally, the feasibility and interest to introduce a strained silicon channel to counteract the degradation of mobility associated with stacking metal / HfO2 are then discussed. Diplôme : Doctorat en sciences En ligne : ../theses/electronique/BEN6980.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10415 Contribution à l’étude du transport électrique à travers des oxydes très minces (<10nm) dans des structures MOS [texte imprimé] / Rachida Bensegueni, Auteur ; Saida Latreche, Directeur de thèse . - 2016 . - 166 f. ; 30 cm. 2 copies imprimées disponibles Langues : Français (fre) Tags : Microelectronic  down-scaling  strained Si channel  high-k dielectric  mobility  gate leakage currents  direct tunneling current  Microélectronique  miniaturisation  MOSFET  Silicium contraint  diélectrique haute permittivité  mobilité  courants de fuites  courant tunnel direct  ???????????? ???????? ???????  ????????? ???????? ?????? ??????  ?????? ???? ????????  ?????? ??????????  ????????  ???? ????? Index. décimale : 621 Electronique Résumé : The continuous down-scaling of MOS transistors dimensions over the last years allowed a significant revolution in the semiconductor industry. However, in order to maintain this trend, shrinking of conventional n MOS dimensions is no more sufficient enough and replacement of some transistor materials is one of the alternative ways currently under study to solve this issue. In this context, the work presented here, on the study of the transport properties of the nMOS architectures combining both new technology options; a high-k gate dielectric in place of the SiO2 and a biaxialy tensile strained channel. Firstly, the influence of biaxial tensile strain on the electrical properties of the n-MOS transistor has been investigated using a numerical solution of drift diffusion partial equations. The simulation results showed a significant improvement in electrons mobility and an increase in current ID (VD). Then, we study the impact of the incorporation of a high-k gate stack on improving leakage through the oxide. The calculation results obtained from the ATLAS (SILVACOTCAD) simulator have shown that the use of high dielectric constant oxides significantly reduces the tunneling leakage current through increased physical thickness of the stack. However, we noted a decrease of the electron mobility in the channel If MOS transistors with a high-k dielectric HfO2 hafnium relative to SiO2 Finally, the feasibility and interest to introduce a strained silicon channel to counteract the degradation of mobility associated with stacking metal / HfO2 are then discussed. Diplôme : Doctorat en sciences En ligne : ../theses/electronique/BEN6980.pdf Format de la ressource électronique : pdf Permalink : https://bu.umc.edu.dz/md/index.php?lvl=notice_display&id=10415

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