Дисертації з теми "Solution SCO"

A series of Fe2+ spin crossover (SCO) complexes [Fe(5/6)]2+ employing hexadentate ligands (5/6) with cis/trans-1,2-diamino cyclohexanes (4) as central building blocks were synthesised. The ligands were obtained by reductive amination of 4 with 2,2′-bipyridyl-6-carbaldehyde or 1,10-phenanthroline-2-carbaldehyde 3. The chelating effect and the rigid structure of the ligands 5/6 lead to exceptionally robust Fe2+ and Zn2+ complexes conserving their structure even in coordinating solvents like dmso at high temperatures. Their solution behavior was investigated using variable temperature (VT) 1H NMR spectroscopy and VT Vis spectroscopy. SCO behavior was found for all Fe2+ complexes in this series centred around and far above room temperature. For the first time we have demonstrated that the thermodynamics as well as kinetics for SCO can be deduced by using VT 1H NMR spectroscopy. An alternative scheme using a linear correction term C1 to model chemical shifts for Fe2+ SCO complexes is presented. The rate constant for the SCO of [Fe(rac-trans-5)]2+ obtained by VT 1H NMR was validated by Laser Flash Photolysis (LFP), with excellent agreement (1/(kHL + kLH) = 33.7/35.8 ns for NMR/LFP). The solvent dependence of the transition temperature T1/2 and the solvatochromism of complex [Fe(rac-trans-5)]2+ were ascribed to hydrogen bond formation of the secondary amine to the solvent. Enantiomerically pure complexes can be prepared starting with R,R- or S,S-1,2-diaminocyclohexane (R,R-trans-4 or S,S-trans-4). The high robustness of the complexes reduces a possible ligand scrambling and allows preparation of quasiracemic crystals of [Zn(R,R-5)][Fe(S,S-5)](ClO4)4·(CH3CN) composed of a 1 : 1 mixture of the Zn and Fe complexes with inverse chirality
Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich

L'objectif de cette thèse est de développer un ensemble de modèles numériques afin de simuler les processus physico-chimiques dans la chambre de combustion ainsi que dans le système de post-traitement des gaz d'échappement des moteurs à combustion interne. Dans la première partie de cette thèse, deux nouveaux modèles d'évaporation de gouttelettes et de film liquide multi-composants sont proposés. Dans le modèle d'évaporation des gouttelettes, une nouvelle expression du débit d'évaporation a été proposée. Il a été montré que la prise en compte du flux de chaleur dû à la diffusion d'enthalpie des espèces est primordiale dans le bilan d'énergie à l'interface de la goutte. De plus, les investigations numériques ont montré l'importance de la prise en compte d'une équation d'état de gaz réel dans les conditions de hautes pressions et / ou de basses températures ambiantes. Un modèle d'évaporation multi-composant de film liquide a ensuite été développé sur la base du modèle d'évaporation de film mono-composant déjà mis en oeuvre dans le code industriel IFP-C3D. En particulier, les lois de paroi ont été généralisées pour l'évaporation du film multi-composant de manière similaire au modèle de l'évaporation des gouttelettes. Il a été montré l'importance de la température de la paroi dans le processus d'évaporation d'un film liquide. Contrairement à l'évaporation des gouttes, les investigations numériques effectuées ont montré que l'utilisation d'une équation d'état de gaz parfait conduit à des résultats proches de ceux qui sont obtenus en utilisant une équation d'état de gaz réel. Ceci se traduit par un gain en temps de calculs important. La deuxième partie de la thèse utilise les modèles d'évaporation, développés dans la première partie de la thèse, avec un nouveau modèle de thermolyse développé afin de produire de l'ammoniac nécessaire pour le système SCR. Dans la présente étude, l'ammoniac est produit à partir de la solution aqueuse d'urée injectée dans la ligne de tuyau d'échappement. L'eau s'évapore et l'urée se décompose en ammoniac nécessaire pour le système SCR. L'évaporation de l'eau est modélisée avec les modèles d'évaporation proposés dans la première partie de cette thèse, avec quelques modifications afin de prendre en compte l'influence de l'urée sur l'évaporation de l'eau. Un nouveau modèle de thermolyse multi-étape pour l'urée a été ensuite implanté dans IFP- 3D afin de simuler la distribution de l'ammoniac gazeux à l'entrée de système de dépollution SCR. Ce modèle est également capable de simuler la formation de sous- roduits (dépôt solide) de la thermolyse d'urée. Les résultats numériques des modèles développés ont permis de montrer le potentiel des développements réalisés au cours de ce travail dans le cadre d'applications industrielles
The aim of the present thesis is to develop a set of numerical models in order to simulate the physical and chemical processes in combustion chamber as well as in exhaust gas after-treatment system of internal combustion engines. In the first part of the thesis, two new multi- omponent evaporation models for droplet and liquid film are proposed. In the droplet evaporation model, a new expression of the evaporation rate has been proposed. It has been shown that taking into account the heat flux due to the enthalpy diffusion of species is of primary significance in the energy balance at the droplet surface. In addition, numerical investigations have shown the importance of considering a real gas equation of state in the high pressure and/or low temperature conditions. A multi-component liquid film evaporation model has then been developed based on the single-component film evaporation model already implemented in IFP-C3D code. Particularly, the wall laws have been generalized for the multi-component film evaporation taking into account the mentioned features applied to the droplet evaporation model. The importance of surface temperature in the evaporation of liquid film has also been shown. Contrary to the droplet evaporation, the numerical investigations on film evaporation have shown that using an ideal mixture equation of state leads to results similar to those obtained using a real gas equation of state. The second part of the thesis uses the evaporation models, developed in the first part of the thesis, along with a new developed thermolysis model in order to produce the ammonia needed for the SCR system. In the present study, ammonia is produced from the urea-water solution injected into the exhaust pipe line. Water evaporates and urea decomposes to ammonia needed for SCR system. The evaporation of water is modeled with the proposed evaporation models in the first part of the present thesis with some modifications in order to take into account the influence of urea on the water evaporation. New multi-step thermolysis model for urea is then implemented in the IFP-C3D code in order to simulate the distribution of gaseous ammonia at the entrance of SCR system. The present model is also able to simulate the formation of solid by-products from urea thermolysis. The numerical results of the developed models allow us to assess the contribution of the developments made during this work in the context of industrial applications

Ingeniero Civil en Computación
Este trabajo se realizó en Sixbell Nekotec Solutions, empresa que provee de soluciones de voz y datos a trav ́es de toda América. Su software permite desde recibir llamadas hasta procesarlas, donde, por ejemplo, se puede implementar un sistema de prepago o un call center. El software central para el trabajo es el SCE, herramienta escrita en JAVA que permite, gráficamente, programar aplicaciones CCXML/VXML, que son las que operan en los sistemas de Sixbell. Su disen ̃o permite, aunque con algunas limitaciones, la introducción de nuevos lenguajes que hacen que este programa pueda cambiar su funcionalidad, pareciéndose más a un IDE de programación gráfica, mediante entidades y enlaces entre ellos, por lo que cualquier problema que pueda ser modelado como flujo o diagrama podría ser resuelto con el SCE. El configurador entonces se empezó a desarrollar como un lenguaje del SCE, pero para po- der ser ocupado completamente, el SCE tuvo que ser modificado y varias partes rediseñadas de manera de no solo se compatible con este nuevo lenguaje, sino que hacer frente desde ya a nuevos problemas que puedan ser modelados con este especie de IDE gráfico. Para ello se modificó la manera en que se dibujan los elementos en pantalla, pues antes solo exist ́ıan flechas para unir las entidades y ahora se pueden poner lineas con flechas en ambos sentidos o sin punta o con punta cuadrada, se hizo un completo refactoring de cómo se comportan los enlaces y demás elementos gráficos y además se trabajó con la retrocompatibilidad para hacer que aplicaciones antiguas del SCE pudieran ser usadas en las nuevas versiones. El configurador terminado permitió a la empresa cambiar su forma de trabajar con los sistemas que venden y usan, desde su creación todos empezaron a adoptarlo como primera opción al configurar un sistema y rápidamente ya se tenían templates de aplicaciones del SCE prácticamente listas para distintos escenarios. Además comenzaron a usarlo en distintos países donde Sixbell está presente como México y Colombia, donde sus unidades de negocio dieron muy buenos comentarios sobre esta herramienta. En conclusión, se logró la creación de una poderosa herramienta, a partir de software ya existente en la empresa lo que da dos resultados positivos para Sixbell : el SCE como un producto aparte que puede modelar y solucionar más problemas que involucren flujos o diagramas, y el configurador que permite a la empresa tener una ventaja frente a sus competidores dadas sus características que benefician a los operadores de los sistemas y ayudan a mejorar los tiempos de puesta en marcha y de reacción frente a escenarios negativos.

On montre par spectroscopie ir que scn forme des liaisons hydrogene avec les solvants pratiques. Dans le methanol plusieurs solvates de cet ion sont identifies. Les paires d'ions entre scn et des cations m**(2+) sont etudiees dans les solvants aprotiques polaires. Les effets sur scn dus a la formation de paires d'ions isothiocyanate mncs sont mis en evidence par spectroscopie ir et raman dans la zone des vibrations cn et cs

Cette thèse s'inscrit dans le cadre d'un projet R&T CNES. Elle concerne l'étude d'un actionneur appelé roue d'inertie, qui fait partie intégrante de l'ensemble SCAO (Système de Contrôle d'Attitude et d'Orbite). Les nouvelles roues proposées, dites Magnétohydrodynamique (MHD) à Conduction, présentent un volant d'inertie fluidique sous forme d'un canal torique, dans lequel un métal liquide conducteur à fort potentiel inertiel est mis en mouvement sous l'effet d'un champ électromagnétique. Contrairement aux roues actuelles, elles n'ont pas de roulements ni d'arbre mécanique ce qui permet un gain en espace, un éloignement idéal de la masse inertielle, et une durée de vie théoriquement illimitée. Aussi, de par la viscosité naturelle du fluide, elles ne présentent pas de non-linéarité autour de la vitesse nulle ce qui évite une perte de précision sur le contrôle du couple de réaction, et donc du pointage du satellite. Le travail réalisé pendant la thèse porte sur l'appréhension des phénomènes MHD consistant en un couplage entre les lois de la Mécanique des Fluides et celles de l’Electromagnétisme, au travers de la loi d’Ohm généralisée. A partir d'hypothèses axisymétriques, et dans le cadre des milieux incompressibles et d’un écoulement laminaire, un modèle générale 3D a pu être établie. Puis une formulation 1D cylindrique a permis une résolution analytique, et une autre en 2D axisymétrique, par résolution numérique en différences fines, a permis l'amélioration de la précision des résultats. Ce modèle a permis de comprendre que deux approches étaient possibles pour la conception et plus particulièrement la commande de l'actionneur. Cette résolution, faisant l'objet du développement d'un code numérique, a d'abord porté sur les équations en régime permanent, puis en temporel, afin de caractériser l'actionneur du point de vue de ses deux modes de fonctionnement. La réalisation d’un prototype a permis de quantifier la validité de la modélisation d’un point de vue dynamique.

An understanding of the interactions between polyelectrolytes and proteins is vital to determine structure and functionality of materials constructed of these two components. Possible applications for the protein-polyelectrolyte composites are ranging from materials used to deliver drugs to the methods of protein stabilisation for storage of therapeutics, biosemsors, and encapsulation of medicines for triggered release. The binding of globular proteins to the polyelectrolyte chains can prevent undesired protein aggregation and may help to extend the shelf-life of the protein-containing food. The aim of this project is to study the mechanism of non-covalent binding between proteins and polyelectrolytes, responsiveness of the proteinpolyelectrolyte composites to external stimuli such as changing pH, presence of salt of different types and concentrations or influence of enzyme on the integrity of protein-polyelectrolyte multilayer film. Our study was focused on the effects of different mono- and multivalent salts on binding affinitybetween a negatively charged polyelectrolyte - poly(styrene sulfonate) PSS and bovine serumalbumin BSA or myoglobin. The complex formation between these polymers was examinedusing the static light scattering (SLS), turbidimetric and potentiometric titrations, differentialscanning calorimetry (DSC) and theoretical studies based on molecular dynamics simulations. We established that the inter- and intramolecular interactions between proteins and polyelectrolytes are primarily driven by the electrostatic forces at the conditions when thepolymers are in low ionic strength solutions and attractive or repulsive relations are based upon the charge density and its distribution. When proteins are interacting with polyelectrolytes in solutions of high ionic strength the electrostatic interactions are screened by the salt originated co-ions. In these conditions there is a competition between salting-out effect on proteins leading to protein aggregation or protein-polyelectrolyte complex formation, which can prevent undesired protein-protein association. The forces driving the attractive interactions at high ionic strength are of non-electrostatic origin, these are mainly hydrophobic forces. The computer simulation study shows that more flexible polyanionic chains are stronger binders to the positive patches on protein surface than these of a more rigid backbone. Also a total energy of binding depends on a sum of electrostatic and non-electrostatic energies. The formation of multilayers composed of a protein and a polyelectrolyte, where componentswere: poly-L-lysine – a positively charged homopolypeptide and polygalacturonic acid - apolysaccharide was examined using a quartz crystal microbalance with dissipation monitoring. A 10 and 11 layer film, deposited on the charged surface, exhibited the linear growth pattern for first 5 layers and exponential growth for a flowing 5 (or 6) layers. The influence of pectinase enzyme on digesting the polygalacturonic acid component of the multilayer was most effective for 1 AU/mL concentration of pectinase. After the enzyme was applied the multilayer film was fully disintegrated within the period of 20 minutes for pectinase at 1 AU/mL and the time of disintegration was extended to 120 minutes for pectinase at 0.1 AU/mL.Silk fibroin aqueous solutions were tested rheologically for their structural properties involvingthe existence of fibroin aggregates. We examined the process of ageing of fibroin solutions and solid-liquid transformations taking place within the fluid. The transitions between viscous and elastic behaviour of the fibroin’s semi-dilute solutions were initiated by strain, shear frequency and temperature. We highlighted that the irreversible change in secondary structure of the silk fibroin in aqueous solutions are taking place after the 48 hour period of time since the preparation of protein fluids. We recommend that further processing of silk fibroin such aselectrospinning should be completed within the 48 hour after dissolution.

NOUS AVONS ETUDIE LA RELATION ENTRE NANOSTRUCTURE ET TRANSITION DE PHASE FERRO-PARAELECTRIQUE, POUR LES MATERIAUX PbSc1/2Ta1/2O3(PST), PbSc1/2O3(PSN) ET LEUR SOLUTION SOLIDE (PSNT). DES IONS DIFFERENTS (SC,TA ET/OU NB) SUR LE SITE B DE LA STRUCTURE PEROVSKITE SONT A L'ORIGINE DE L'APPARITION DE SURSTRUCTURES DONT L'IMPORTANCE REND LA TRANSITION PLUS OU MOINS DIFFUSE. DES MONOCRISTAUX ONT ETE SYNTHETISES AFIN DE POUVOIR TRAVAILLER SUR DES PHASES PURES. ILS PRESENTENT PAR DIFFRACTION DES RAYONS-X A TEMPERATURE AMBIANTE UNE STRUCTURE MOYENNE CUBIQUE, MEME SI POUR PSN LES MESURES SONT EFFECTUEES EN PHASE FERROELECTRIQUE (Tc= 90°C). UNE SURSTRUCTURE DE TYPE {111} APPARAIT POUR PST ET PSNT, CONDUISANT A UN RESEAU F ALORS QUE LE RESEAU DE BASE EST P POUR PSN. PAR DIFFRACTION ELECTRONIQUE, LA SURSTRUCTURE {111} EST MISE EN EVIDENCE DANS LES TROIS COMPOSES ET DE NOUVELLES REFLEXIONS DE TYPE 110 SONT OBSERVEES, LES IONS Sc3+,TA5+ ET/OU Nb5+ ETANT DISTRIBUES REGULIEREMENT SUR LES PLANS {111} OU SUR LES PLANS {110}. LES IMAGES EN FOND NOIR MONTRENT UN ORDRE {111} A LONGUE DISTANCE, OCCUPANT LA QUASI-TOTALITE DES CRISTAUX POUR PST ET PSNT AVEC DES TAILLES DE DOMAINES ALLANT JUSQU'A 60NM ALORS QUE DANS PSN LEUR DIMENSION EST DE L'ORDRE DE 4nm. L'ETUDE DE LA TRANSITION DE PHASE PAR MESURES DIELECTRIQUES ET CALORIMETRIQUES MONTRE LA SUPERPOSITION DE DEUX ACCIDENTS. LES REGIONS ORDONNEES DE TYPE {111} TRANSITENT VERS UNE PHASE FERROELECTRIQUE ET SONT RESPONSABLES D'UN PIC DE PERMITTIVITE DIELECTRIQUE NON DIFFUS ET DE LA CHALEUR LATENTE OBSERVEE. LE VOLUME DESORDONNE PROVOQUE UN ACCIDENT PLUS DIFFUS DONT L'ORIGINE POURRAIT ETRE UN CHANGEMENT DE COMPORTEMENT DE NANOREGIONS POLAIRES, DEJA PRESENTES A PLUS HAUTE TEMPERATURE

Le contexte dans lequel s’inscrivent les travaux de thèse est la réduction catalytique sélective des émissions automobiles d’oxyde d’azote (NOx), appelée SCR (Selective Catalyst Reduction). Elle s’effectue par une injection directe à l’échappement d’une solution aqueuse d’urée qui offre une sélectivité favorable vis-à-vis des NOx. Cette technologie comprend également en aval de l’injecteur, un catalyseur dédié qui accélère la cinétique de réduction des NOx. Comme pour tous procédés utilisant un spray, l’efficacité de la SCR dépend des caractéristiques de celui-ci. Aussi les travaux de recherche se sont focalisés sur le spray avec l’analyse des distributions de taille de gouttes, puis la simulation de l’évolution du spray. Le code CFD ne disposant pas d’un modèle d’atomisation primaire adapté, une méthode a été proposée. Cette méthode repose sur l’utilisation de la distribution de taille de gouttes du spray mesurée par un granulomètre à diffraction laser. Pour cela, un modèle de distribution initiale de taille de gouttes a été établi à partir de la fonction Gamma Généralisée à trois paramètres. Ce modèle permet d’obtenir la distribution mathématique de taille de gouttes du spray, qui reproduit la distribution mesurée par le granulomètre. La distribution mathématique ainsi obtenue est utilisée comme distribution initiale du spray dans le code CFD. La validation des résultats de simulation numérique a été effectuée en comparant les distributions de taille de gouttes du spray. Le bon accord entre les résultats de simulation numérique et expérimentaux montre que le modèle mathématique défini à partir des distributions expérimentales comporte la quantité nécessaire d’informations sur le spray
The context within the thesis was carried out is the selective catalytic reduction of nitrogen oxide emissions cars (NOx), called SCR (Selective Catalytic Reduction). It is carried out by direct injection into the exhaust of an aqueous urea solution which offers a favorable selectivity to the NOx. This technology also includes downstream of the injector, a dedicated catalyst that accelerates the kinetics of NOx reduction. As with all processes using a spray, the effectiveness of SCR depends on the characteristics of it. Also the research was focused on the spray with the analysis of the experimental drop size distributions and the simulation of the evolution of the spray. The CFD code does not have an adapted primary atomization model, therefore a method has been proposed. This method is based on the use of a spray drop size distribution measured by a laser diffraction granulometer. For this, an initial drop size distribution model was determined from the Generalized Gamma function with three parameters. This model provides the mathematical drop size distribution of the spray, which reproduces the distribution measured by the particle sizer. The mathematical distribution thus obtained is used as the initial distribution of the spray in the CFD code. The validation of the numerical simulation results was performed by comparing with the experimental drop size distributions. The good agreement between the numerical and the experimental results shows that the mathematical model defined from the experimental drop size distribution has the necessary amount of information on the spray

The main goal of this thesis work is the production and characterization of Tin oxide thin film deposited via Solution Combustion Synthesis (SCS). Different precursors are used in order to study the effect of the chemical nature of the reagent on the structural, morphological and electrical properties of the thin films. Tin oxide was chosen because is one of the most promising candidates for p-type oxide. In fact, the semiconductor oxides reported in the literature are mostly limited to n-type and there is a need for solution processed p-type oxide semiconductors to achieve Complementary Metal Oxide Semiconductors (CMOS) using all oxide materials. Anyway, the production window of solution processed for p-type SnO is narrow and Silver doping will be used to enhance the probability to get it. If production of p-type Tin oxide will not be achieved, the work will be focused on n-type SnO2 and on the optimisation of devices made with this material, either Thin Film Transistors (TFTs) or Transparent Conductive Oxides (TCOs). Samples made in this work show good optical properties, like transmittance over 80% and energy gap values around 3.79 eV, but none of them turned out to be a p-type oxide or a good TFT. Samples annealed at higher temperatures have good electrical conductivity properties, which could lead to a future study in order to optimise these materials for TCO purposes.

Today’s business market is highly competitive, therefore companies need to be constantly updated and change the way they operate their business, in order to survive and remain competitive. The situation on today’s market requires that companies have the ability to quickly respond to market changes and new customer demands within short product lifecycles. In order to deal with this new market situation, companies need to improve the integration with other companies within their business. This integration facilitates the companies’ ability to quickly adapt to new market situations and survive on a fast changing market. One of the main underlying concepts of this collaborative commerce is Supply Chain Management (SCM) which integrates and coordinates a company’s processes both internally and externally. Information Technology (IT) could improve the effectiveness of SCM. IT-solutions make the business processes more effective and improves the integration with other actors within the supply chain. The purpose with this thesis is to describe and explain the effects for businesses and the consequences for its processes when implementing a real-time IT-Logistics solution together with identifying the critical success factors. The thesis has been conducted by studying theory regarding supply chain management, business renewal and implementation effects. Further, a case study has been conducted where three actors have been interviewed; a manufacturer (Volvo Powertrain), a subcontractor (Metallfabriken Ljunghäll AB) and a system developer (PipeChain). The analysis of the theoretical framework and the empirical research has contributed with an identification of major effects and consequences when implementing a real-time IT-Logistics solution. Some of the effects are: inventory reduction, higher delivery accuracy, improved relations and increased flexibility. Examples of consequences these effects have caused are: more accurate planning and production, effective production processes as well as an improved delivery process. Additionally, success factors for an implementation have been identified such as mutual trust, understanding of change and evaluation.

Konkurrensen är stor inom dagens affärsmarknad vilket medför att företag ständigt måste vara uppdaterade och förändra deras affärsverksamhet för att kunna överleva och vara konkurrenskraftiga på marknaden. Dagens marknadssituation erfodrar att företag snabbt kan reagera på marknadsförändringar och nya kundkrav vid allt kortare produktlivscyklar. För att företag skall kunna hantera denna nya marknadssituation måste företagen bli integrerade med varandra inom deras affärsområde. Denna integrering underlättar företagens förmåga att snabbt kunna anpassa sig till nya marknadssituationer och överleva på en snabbt föränderlig marknad. Ett utav de största grundläggande koncepten för denna integrering är flödeshantering (Supply Chain Management). Flödeshanteringen integrerar och koordinerar företagets processer både internt som externt. Informationsteknologi (IT) kan förbättra effektiviteten av flödeshanteringen. IT-lösningar skapar effektivare affärsprocesser och förbättrar integrationen med andra aktörer inom företagets försörjningskedja. Syftet med uppsatsen är att beskriva och förklara effekter för affärsverksamheten samt konsekvenser för dess affärsprocesser, vid en implementering av en realtidslogistiklösning. Uppsatsen syftar vidare till att identifiera framgångsfaktorer vid en sådan implementering. Uppsatsarbetet har genomförts genom en litteraturstudie där teori om flödeshantering, affärsförändring och implementationseffekter har behandlats. En fallstudie i uppsatsen har använts där tre aktörer har blivit intervjuade; en tillverkare (Volvo Powertrain), en underleverantör (Metallfabriken Ljunghäll) och en systemutvecklare (PipeChain). Analysen av litteraturstudien och den empiriska undersökningen har bidragit till en identifiering av huvudeffekter samt konsekvenser vid en implementering av en IT-logistiklösning. Några av dessa effekter är: lagerreducering, högre leveranssäkerhet, förbättrade relationer samt ökad flexibilitet. Exempel på konsekvenser dessa effekter har orsakat är: precisare planering och produktion, effektivare produktionsprocesser samt förbättrad leveransprocess. Vidare så har framgångsfaktorer för lyckad implementering identifierats så som ömsesidig tillit, förståelse för förändring samt utvärdering.

Le travail présenté dans ce mémoire est divisé en deux parties. La première partie est consacrée aux calculs des fonctions d'appui de la Jacobienne généralisée de Clarke et de son enveloppe plénière, associées à une fonction localement lipschtizienne à valeurs vectorielles. Clarke avait établi en 1975 que la fonction d'appui du sous-différentiel généralisé était une dérivée directionnelle généralisée. Il est donc satisfaisant de constater que la fonction d'appui de la Jacobienne généralisée est une sorte de "divergence directionnelle généralisée". Dans la seconde partie, nous présentons un certain nombre d'applications de techniques issues de l'Analyse non lisse à la résolution d'équations de Hamilton-Jacobi du premier ordre. Ainsi nous utilisons la dualité convexe et le calcul sous-différentiel pour prouver que les formules dites de Hopf-Lax définissent des solutions explicites des équations de Hamilton-Jacobi associées (avec données initiales semicontinues inférieurement). Nous n'utilisons ni le fameux principe de comparaison de la théorie des solutions de viscosité ni régularisation. Nous traitons successivement le cas de la dimension finie et de la dimension infinie. Ces résultats nous permettent de trouver des estimations des solutions d'équations dont l'hamiltonien est la différence de deux fonctions convexes. Enfin, nous nous attachons à l'étude des solutions sci dans des espaces de Banach dits ``lisses''. Le théorème de la valeur moyenne de Clarke et Ledyaev nous permet de montrer un résultat d'``enveloppe'' : nous construisons une solution sci pour une équation dont l'hamiltonien est le supremum d'une famille d'hamiltoniens. Nous appliquons enfin les mêmes techniques pour prouver l'existence d'une solution sci minimale sous des hypothèses plus faibles que celles que l'on recontre généralement dans la littérature.

Le travail presente dans ce memoire est divise en deux parties distinctes. La premiere partie est consacree aux calculs des fonctions d'appui de la jacobienne generalisee de clarke et de son enveloppe pleniere, associees a une fonction localement lipschtizienne a valeurs vectorielles. Clarke avait etabli en 1975 que la fonction d'appui du sous-differentiel generalise etait une derivee directionnelle generalisee. Il est donc satisfaisant de constater que la fonction d'appui de la jacobienne generalisee est une sorte divergence generalisee. Dans la seconde partie, nous presentons un certain nombre d'applications de techniques issues de l'analyse non lisse a la resolution d'equations de hamilton-jacobi du premier ordre. Ainsi nous utilisons la dualite convexe et le calcul sous-differentiel pour prouver que les formules dites de hopf-lax definissent des solutions explicites des equations de hamilton-jacobi associees (avec donnees initiales semicontinues inferieurement). Nous n'utilisons ni le fameux principe de comparaison de la theorie des solutions de viscosite ni regularisation. Nous traitons successivement le cas de la dimension finie et de la dimension infinie. Ces resultats nous permettent de trouver des estimations des solutions d'equations dont l'hamiltonien est la difference de deux fonctions convexes. Enfin, nous nous attachons a l'etude des solutions sci dans des espaces de banach dits lisses. Le theoreme de la valeur moyenne de clarke et ledyaev nous permet de montrer un resultat d'enveloppe : nous construisons une solution sci pour une equation dont l'hamiltonien est le supremum d'une famille d'hamiltoniens. Nous appliquons enfin les memes techniques pour prouver l'existence d'une solution sci minimale sous des hypotheses plus faibles que celles que l'on rencontre generalement dans la litterature. .

Through a harmonization of IT-tools among intraorganizational units synergies can be attained through economies of scale and homogenous interfaces towards supply chain partners. In this thesis the possibilities for such synergies at Siemens Medical Solutions in Germany are investigated. By evaluating performance of IT-tools and the cost impact of different scenarios recommendations for harmonization at Siemens Medical Solutions are given.

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Secretaria do Estado e Educação
This research aims at looking into dissertative-argumentative texts that are required by the School Performance Evaluation System of São Paulo State (SARESP) in order to check in which way this text is useful or not in signaling to the reader of the training phases of the Problem-Solution structure, by Hoey (1994). In accordance with Cereja & Magalhães (2003), although most applicants to the University entrance examinations are asked to produce dissertative texts, in reality due to the controversial nature of the proposed themes, very often what is expected from the applicant is that they produce either an argumentative or a dissertative-argumentative text. According to Conceição (2000), the written production turns out into one of greatest concerns of Portuguese Teachers. There are countless diagnoses that detect the most varied kinds of problems. There are several questions involved in such a situation, one of which could be the complete unfamiliarity of the student with the genre that the texts they have been asked to write belongs to. In this aspect the words by Bakhtin (1997) are very clearing when he defines the genre of discourse. He states that no matter how varied all the fields of human activity might be they will always be related to the use of language. Therefore we can undestand the importance that is given to concept of genre in Vigner s words (1988), when stating that recognizing a genre is being able to regulating its reading over a system of expectation, inscribing in a previsible trajectory considering that this recognition operates as from the aprehension of a certain number of signs. It is known that the production and understanding of a text walk side by side: they are both faces of the same coin (Ikeda 1986). Therefore, the production of a fluent and intelligible text should be a reader-friendly text, that makes the reader s understanding easier. The methodology of analysing the texts will be supported by the definition of genre, by the Systemic-Functional Language (LSF), that deals with the schematic structure of the text; this being the notion that helps understanding the constitution of a genre in its stages (Martin, 1992). As the LSF does not deal specifically with the dissertative -argumentative genres, we searched for subsidies especially in Hoey (1994), whose proposal of a Problem- Solution structure seems more appropriate to us besides being very clearing for examining this specific question. As a supplement to this proposal, we supported ourselves also on Vigner (1988)
Esta pesquisa tem como objetivo examinar textos dissertativo-argumentativos solicitados no Sistema de Avaliação de Rendimento Escolar do Estado de São Paulo (SARESP) para verificar de que maneira esse texto é bem sucedido ou não na sinalização para o leitor dos estágios da estrutura Problema-Solução, de Hoey (1994). De acordo com Cereja & Magalhães (2003), embora na maior parte dos exames vestibulares do país se solicite aos candidatos à produção de textos dissertativos, na verdade, pela natureza polêmica dos temas, quase sempre o que se espera do candidato é que ele produza um texto argumentativo ou dissertativo - argumentativo. Segundo Conceição (2000), a produção escrita constitui-se numa das grandes preocupações dos professores de português. São inúmeros os diagnósticos detectando os mais variados problemas. Há várias questões envolvidas nessa situação, uma das quais pode ser o desconhecimento por parte do aluno do gênero a que pertence a redação que lhe é solicitada. Nesse aspecto, são extremamente elucidativas as palavras de Bakhtin (1997), quando define gênero do discurso. Ele afirma que, por mais variadas que sejam, todas as esferas da atividade humana estão sempre relacionadas com a utilização da língua. Daí podermos entender a importância dada ao conceito de gênero nas palavras de Vigner (1988), que diz que reconhecer um gênero é poder regular sua leitura sobre um sistema de expectativa, inscrevê-la numa trajetória previsível, sendo que este reconhecimento opera a partir da apreensão de um certo número de sinais. Sabe-se que produção e compreensão de um texto caminham juntas: são ambas facetas de uma mesma moeda (Ikeda 1986). Assim, a produção de um texto fluente e inteligível deve ser um texto amigo-do-leitor , facilitando-lhe a compreensão. A metodologia de análise dos textos terá apoio na definição de gênero, pela Lingüística Sistêmico-Funcional (LSF), que trata da estrutura esquemática do texto, noção que ajuda a entender a constituição de um gênero em estágios (Martin,1992). Na medida em que a LSF não trata especificamente do gênero dissertativo -argumentativo, fomos buscar subsídios especialmente em Hoey (1994), cuja proposta de estrutura Problema-Solução parece-nos adequada e muito esclarecedora para examinar essa questão específica. Complementando essa proposta, apoiamo-nos também em Vigner (1988)

Supply Chain Event Management (SCEM) bezeichnet eine Teildisziplin des Supply Chain Management und ist für Unternehmen ein Ansatzpunkt, durch frühzeitige Reaktion auf kritische Ausnahmeereignisse in der Wertschöpfungskette Logistikleistung und -kosten zu optimieren. Durch Rahmenbedingungen wie bspw. globale Logistikstrukturen, eine hohe Artikelvielfalt und volatile Geschäftsbeziehungen zählt die Modeindustrie zu den Branchen, die für kritische Störereignisse besonders anfällig ist. In diesem Sinne untersucht die vorliegende Dissertation nach einer Beleuchtung der wesentlichen Grundlagen zunächst, inwiefern es in der Modeindustrie tatsächlich einen Bedarf an SCEM-Systemen gibt. Anknüpfend daran zeigt sie nach einer Darstellung bisheriger SCEM-Architekturkonzepte Gestaltungsmöglichkeiten für eine Systemarchitektur auf, die auf den Designprinzipien der Serviceorientierung beruht. In diesem Rahmen erfolgt u. a. auch die Identifikation SCEM-relevanter Business Services. Die Vorzüge einer serviceorientierten Gestaltung werden detailliert anhand der EPCIS (EPC Information Services)-Spezifikation illustriert. Abgerundet wird die Arbeit durch eine Betrachtung der Nutzenpotenziale von SCEM-Systemen. Nach einer Darstellung von Ansätzen, welche zur Nutzenbestimmung infrage kommen, wird der Nutzen anhand eines Praxisbeispiels aufgezeigt und fließt zusammen mit den Ergebnissen einer Literaturrecherche in eine Konsolidierung von SCEM-Nutzeffekten. Hierbei wird auch beleuchtet, welche zusätzlichen Vorteile sich für Unternehmen durch eine serviceorientierte Architekturgestaltung bieten. In der Schlussbetrachtung werden die wesentlichen Erkenntnisse der Arbeit zusammengefasst und in einem Ausblick sowohl beleuchtet, welche Relevanz die Ergebnisse der Arbeit für die Bewältigung künftiger Herausforderungen innehaben als auch welche Anknüpfungspunkte sich für anschließende Forschungsarbeiten ergeben.

Spin crossover (SCO) active metal complexes are highly versatile materials thanks to their sensitivity to tiny physical or chemical environmental changes. This property makes them very useful for a wide range of applications: employable for experimental studies as molecular switches or for theoretical studies investigating the M-L bonds. In both cases, these studies aim to develop strategies of predictably tuning them. Chapter One. An introduction to the SCO phenomenon: from gradual to cooperative SCO; various methods of monitoring the SCO transition. A summary of some literature examples of SCO-active systems is given. An overview of the published achievements in predicting the SCO phenomenon, including an introduction to the computational models deployed across the years. The EDA-NOCV model, employed in this field for the first time in this PhD thesis, is introduced. Finally, the aims of this study are presented. Chapter Two. The synthesis and characterisation of four new non-symmetrical ligands, 3-(2-(5-Z-pyridyl))-4-tolyl-5-phenyl-1,2,4-triazole (LpytZ, Z = CF3, Br, F, Me), and the corresponding [FeII(LpytZ)2(NCBH3)2] complexes are presented. All four of these new complexes are SCO-active in the solid state and in CDCl3 solution, but T1/2 tuning by the meta-Z substituents was very modest. Three literature families were also tested, successfully extending the generality of using the 15N NMR chemical shift δNA of the coordinated nitrogen atom of the free ligand as measure of the T1/2 in the resulting Fe(II) complex. Chapter Three. Theoretical study of a family of five iron(II) SCO-active [Fe(Lazine)2(NCBH3)2] (Lazine = 3-(2-azinyl)-4-tolyl-5-phenyl-1,2,4-triazole) and of the related five LS [Fe(Lazine)3(BF4)2]. The EDA-NOCV model was applied to molecular fragments to provide quantitative assessment of the σ- and π-bonding. A new corrected [Mn+ + L6] fragmentation was implemented which promises to enable a general approach suitable for any ML6 system. Finally, the σ- and π-bonding character is strongly correlated with the experimental T1/2 of the SCO-active [Fe(Lazine)2(NCBH3)2] complexes. Chapter Four. Theoretical study of the M-L bond in a family of sixteen SCO-active differently para-X substituted [Fe(bppX)2]2+ complexes (bppX is 2,6-di(pyrazol-1-yl)-4-X-pyridine). Results of the EDA-NOCV revealed the σ-strength of the bppX ligand is correlated with σp+(X), δNA(bppX), experimental T1/2([Fe(bppX)2]2+) and calculated AILFT ΔO([Fe(bppX)2]2+). Results are explained at the molecular level by investigating the orbital population of the valence orbitals of the coordinating nitrogen involved in the aromatic π-system (pπ) and in the Fe-N bond (sp2(Fe)). From the observed correlations, the unknown σp+ parameter for two substituents (X = SOMe, SO2Me) is predicted. Chapter Five. First theoretical study on [CoII(dpzca)2] SCO in the solid state, aiming to establish a computational protocol able to predict experimental T1/2 in pressure-activated SCO. The first part of the study validated a DFT protocol at p = 1 bar. The protocol was then extended and trialled up to 4300 bar. Results revealed good reproduction of the experimental results up to 2100 bar; but beyond this pressure, the theoretical and experimental findings diverge. Theoretical data suggest a possible phase change for the crystalline structure of HS [CoII(dpzca)2] at higher pressures than 2100 bar; this would explain why the implemented computational protocol lost validity.

碩士
國立臺灣大學
土木工程學研究所
91
Analysis of Timoshenko beams are conducted using the spline collocation ( interpolation ) method ( SCM ) , which have been studied and illustrated in this paper in order to be easily applied for engineers . The B splines value table is originately set up in this paper, which is easily to be used and suggested to be applied in analyzing the structures with any form of loading and boundary conditions. Results are compared with those obtained by the differential quadrature method (DQM) and available analytic results. Very good results are obtained so that we can expect to develop this method further for more complicated structures.

碩士
國立臺灣大學
土木工程學研究所
91
Analysis of elastic columns are conducted using the spline collocation ( interpolation ) method ( SCM ) , which have been studied and illustrated in this paper in order to be easily applied for engineers . The B splines value table is originately set up in this paper, which is easily to be used and suggested to be applied in analyzing the structures with any form of loading and boundary conditions. Results are compared with those obtained by the differential quadrature method (DQM) and available analytic results. Very good results are obtained so that we can expect to develop this method further for more complicated structures.

碩士
國立交通大學
管理學院碩士在職專班資訊管理組
98
In electronic marketplace, consumers have many choices because there are many competiors produce alike products for one application field. The only constant is “change” in the diversity of industry supply chain. The main goal of each company is to achieve the competitive advantage of supply chain management. But the big challenge is how to obtain a supply-demand balance in the condition of complicated product components. Uncertainties may cause supply-demand imbalance, and result in excess inventory, or sales lost due to late delivery. An IC design house plays as a part supplier in the industrial supply chain. Its upstream are distributors and direct customers, whereas its downstream are production outsourcing vendors. Most of product selling and manufacturing information are outside the company system, and many uncertainties exist, if “change” inevitable then “rapid-response” is naturally a good guiding principle in supply chain management. To achieve rapid-response, information transparency across the entire supply chain is necessary. Beside, to increase the accuracy and completeness of an information system is also required,. This research focuses on implementing a total-solution supply chain management system, to integrate all of demand and supply information from both its upstream and its downstream.

This thesis deals with a new solution for medium voltage drives. Load Commutated Inverter (LCI) fed synchronous motor drive is a popular solution for high power drive applications. Though the induction machine is more rugged and cheaper compared to the synchronous machine, LCI fed induction motor drive solution is not available. The basic advantage of a synchronous machine over an induction machine is the fact that the synchronous machine can operate at leading power factor. Due to this property load commutation of SCR switches of the LCI is achievable for synchronous machine. On the contrary an induction machine always draws lagging power factor current; this makes it unsuitable as a drive motor for LCI technology. In this thesis a new LCI fed induction motor drive configuration is developed as an alternative for synchronous motor drives. A new variant of six phase induction motor is proposed in this context. The machine is named as Active Reactive Induction Machine (ARIM). The ARIM contains two sets of three-phase windings with isolated neutral. Both the windings have a common axis. One winding carries the active power and can be wound for higher voltage (say 11kV). The other winding supplies the total reactive power of the machine and can be wound for lower voltage (say 2.2 kV). The rotor is a standard squirrel cage. High power induction machines usually demand lesser magnitude of reactive power compared to the total power rating of the machine ( 20% ). Therefore excitation winding has a smaller fraction of the total machine rating compared to the power winding. A VSI with an LC filter supplies reactive power to the ARIM through the excitation winding and ensures leading power factor at the power winding. This is similar to the excitation control of the LCI fed synchronous machine. The direct VSI connection is possible due to the lower voltage rating for the excitation winding. In this way, the VSI voltage rating does not limit the highest motor voltage that can be handled. An LCI supplies the real power into the ARIM from the power winding. The LCI currents are quasi square wave in shape. Therefore they have rich low order harmonic content. They cause 6th and 12th harmonic torque pulsations in the machine. This is a problem for the LCI fed synchronous machine drive. In the proposed drive, the VSI can compensate these low frequency m.m.f. harmonics inside the machine air gap to remove torque pulsation and rotor harmonic losses. The advantage of the proposed topology is that no transformer is required to drive an 11kV machine. It is always desirable to feed sinusoidal voltage and current to both the power winding and the excitation winding. To address this problem, a second configuration is proposed. A low power three-level VSI is connected in shunt at the power winding with the proposed ARIM drive as discussed above. This VSI compensates the low frequency harmonic currents to achieve sinusoidal motor currents at the motor winding. This VSI acts as a shunt active filter and compensates for the lower order harmonics injected by the LCI. The proposed topologies have LC filters to maintain sinusoidal motor voltages and currents by absorbing the VSI switching frequency components. But the motor terminal voltage oscillates at system resonant frequency due to the presence of LC filters. These resonant components in the terminal voltages are required to be eliminated for smooth terminal voltages and safe load commutation of the thyristors. In this thesis a simple active damping method is proposed to mitigate these issues. The proposed topologies are experimentally verified with an ARIM with 415 V power winding and 220 V excitation winding. The control is carried out on a digital platform having a TMS 320LF 2407A DSP processor and an ALTERA CYCLONE FPGA processor. Results from the prototype experimental drive are presented to show the feasibility and performance of the proposed drive configurations.

碩士
清雲科技大學
機械工程所
100
The present study used electroless plating techniques by adding nano-TiO2 in the plating solution with various concentrations of 1 g/L, 5 g/L, 10 g/L and 15 g/L to form Ni-P/nano TiO2 composite coatings on the 70Cu-30Zn brass alloy substrate. The corrosion resistance behavior was evaluated by potentiodynamic measurement and the susceptibility of the stress corrosion cracking (SCC) was evaluated by slow strain rate test (SSRT) in 0.1 M NaF solution. The surface morphology, element analysis and surface microhardness of the electroless Ni-P composite coatings were observed and analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and vicker’s microhardness tester. Experimental results indicated that the electroless Ni-P plating coating had a beneficial effect to enhance the hardness as well as corrosion and SCC resistance of brass alloy in 0.1 M NaF solution. When the nano-TiO2 particles added this beneficial effect was significantly raised with increasing the concentrations of nano TiO2 up to 15 g/L. The improved SCC resistance was attributed to the electroless Ni-P/nanoTiO2 composite coatings preventing the formation of an unstable Cu2O passive film for brass alloy in fluoride solution. This unstable passive film could be destroyed by strain and F- attack during slow strain rate tensile test, and resulting in dezincification dissolution and an intergranular stress corrosion cracking (IGSCC) of the brass alloy.

Compression fracture specimens are ideally suited for miniaturization down to tens of microns. Fracture testing of thermal barrier coatings, ceramics and glasses are also best accomplished under compression or indentation. Compression fracture specimen of finite size with constant form factor was not available in the literature. The finite-sized specimen of edge cracked semicircular disk (ECSD) is designed which has the property of constant form factor. The novel ECSD specimen is explored further using weight function concept. This thesis, therefore, is mainly concerned with the design, development and geometric optimization of compression fracture specimen vis a vis their characterization of form factors, weight functions and isotropic points in the uncracked geometry. Inspired by the Brazilian disk geometry, a novel compression fracture specimen is designed in the form of a semicircular disk with an edge crack which opens up due to the bending moment caused by the compressive load applied along its straight edge. This new design evolved from a set of photoelastic experiments conducted on the Brazilian disk and its two extreme cases. Surprisingly, normalized mode-I stress intensity factor of the semicircular specimen loaded under a particular Hertzian way, is found constant for a wide range of relative crack lengths. This property of constant form factor leads to the development of weight function for ECSD for deeper analysis of the specimen. The weight function of a cracked geometry does not depend on loading configuration and it relates stress intensity factor to the stress distribution in the corresponding uncracked geometry through a weighted integral. The weight function for the disk specimen is synthesized in two different ways: using the conventional approach which requires crack opening displacement and the dual form factor method which is newly developed. Since stress distribution in the uncracked specimen is required in order to use weight function concept, analytical solution is attempted using linear elasticity theory. Since closed form solution for stresses in the uncracked semicircular disk is seldom possible with the available techniques, a new semi-analytical method called partial boundary collocation (PBC), is developed which may be used for solving any 2-D elasticity problem involving a semi-geometry. In the new method, part of the boundary conditions are identically satisfied and remaining conditions are satisfied at discrete boundary points. The classical stress concentration factor for a semi-in finite plate with a semicircular edge notch re-derived using PBC is found to be accurate to the eighth decimal. To enhance the form factor in order to test high-toughness materials, edge cracked semicircular ring (ECSR) specimen is designed in which bending moment at the crack-tip is increased significantly due to the ring geometry. ECSR is analyzed using nite element method and the corresponding uncracked problem is analyzed by PBC. Constant form factor is found possible for the ring specimen with tiny notch. In order to avoid varying semi-Hertzian angle during practice and thereby ensure consistent loading conditions, the designs are further modified by chopping at the loading zones and analyzed. Photoelastic isotropic points (IPs) which are a special case of zeroth order fringe (ZOF) are often found in uncracked and cracked specimens. An analytical technique based on Flamant solution is developed for solving any problem involving circular domain loaded at its boundary. Formation of IPs in a circular disk is studied. The coefficients of static friction between the surfaces of disk and loading fixtures, in photoelastic experiments of three-point and four-point loadings, are explored analytically to confirm with experimental results. The disk under multiple radial loads uniformly spaced on its periphery is found to give rise to one isolated IP at the center. Splitting of this IP into a number of IPs can be observed when the symmetry of normal loading is perturbed. Tangential loading is introduced along with normal loading to capture the effect of the composition on formation of IPs. Bernoulli's lemniscate is found to fit fringe order topology local to multiple IPs. Isotropic points along with other low fringe order zones including ZOF are ideal locations for material removal for weight reduction. Making a small hole in the prospective crack path at the IP location in the uncracked geometry might provide dual benefits: 1. Form factor enhancement; 2. Crack arrestor. Thus, this thesis describes experimental, theoretical and computational investigations for the design, development and calibration of novel compact compression fracture specimens.

Vanadium oxides are being used as the thermal sensing layer because of their applications in infrared detectors. They have high temperature coefficient of resistance, favorable electrical resistance and compatibility with the MEMS technology. Of all oxides of vanadium, only vanadium dioxide (VO2)has been highly investigated as it shows first order transition (semiconducting to metal transition-SMT)at 68 oC. First order transition is understood as the sharp change in the electrical resistance. The change in resistivity in this case is of the order of 105 over a temperature change of 0.1 oC at 68 oC in a single crystal. Doping vanadium oxides with elements like Mo and W reduce the transition temperature. This is very important for room temperature electrical and optical detection. Though most of the research groups subscribe to PLD, cost-effective methods with large area deposition are major focus of this research. Hence for synthesizing VO2 in bulk and thin films, Solution Combustion Synthesis (SCS), Ultrasonic Nebulized Spray Pyrolysis of Aqueous Combustion Mixture (UNSPACM) Chemical vapour deposition (CVD)and microwave are explored. Synthesis of doped VO2 films in CVD has not been done extensively to yield optical quality thin films. Chapter I surveys the use of phase transition in oxides system for a variety of practical applications. In particular, Vanadium dioxide (VO2) is chosen as it is found to be very useful for infrared and metamaterials based applications. VO2 is known for its first-order semiconducting to metallic transition (SMT). This chapter attempts to explain the influence of processing, doping, annealing, etc on the SMT characteristics. Important aspects such as the idea of hysteresis in VO2 and similarity to martensitic transformation are discussed. The scope and objectives of the thesis are discussed here. Chapter II explains in detail the materials and methods used to synthesize VO2 both in bulk and in thin lm form and methods used to study their characteristics. Brief description on the principle and the working of the home-built experimental set up needed for this study is elicited. In chapter III, attempts were made to understand the phase stability of VO2 and the evolution of crystal structures during the phase transition. VO2 crystallizes in P21/c space group at room temperatures with lattice parameters a=5.752 Ab=4.526 Ac=5.382 Aα=90 β=122.60 γ=90 . Precise control of synthesis parameters is required in stabilizing pure phase in bulk as well as thin lm form. This study focuses on the novel large scale two step synthesis of VO2 using Solution Combustion Synthesis. This involves synthesis of product utilizing redox reaction between metal nitrate and suitable fuel. Generally the products are nanocrystalline in nature due to self-propagation of the exothermic combustion reaction. First step involved the synthesis of V2O5 by combustion reaction between Vanadyl nitrate and urea. In the second step, the as-synthesized V2O5 has been reduced by a novel reduction technique to form monophasic VO2. The presence of competing phases like M1, M2, M3 and R are investigated by XRD, Raman spectroscopy, DSC, Optical and high temperature X-ray diffraction. Chapter IV deals with the reduction in phase transition temperature by doping the SCS synthesized VO2 with W and Mo. Effect of doping on the transition temperature was studied using differential scanning calorimetry (DSC) in both W and Mo. Electrical characteristics of Mo doped VO2 and Optical characteristics of the W-doped VO2 were also studied using four probe resistivity measurements and UV-VIS Spectroscopy respectively. W addition was found to be more effective in reducing the phase transition temperature. To understand further more on the W addition, X-ray photo-electron spectroscopy measurements were performed. W-addition alters the V4+-V4+ bonding and with W addition it is observed that V was present in V3+state. W was present in W6+ state. The addition of W to VO2 introduces more electrons to the systems and disturbs the V4+-V4+ thus reducing the phase transition temperature of VO2. Chapter V describes the large scale, large area deposition of thin films of VO2 by a cost effective method. A novel technique to deposit vanadium dioxide thin films namely, UNSPACM is developed. This simple two-step process involves synthesis of a V2O5 lm on an LaAlO3(LAO) substrate followed by a controlled reduction to form single phase VO2. The formation of M1 phase (P21/c) is confirmed by Raman spectroscopic studies. A thermally activated metal{insulator transition (MIT) was observed at 61 oC, where the resistivity changes by four orders of magnitude. The infrared spectra also show a dramatic change in reflectance from 13% to over 90% in the wavelength range of 7-15 m. This indicates the suitability of the films for optical switching applications at infrared frequencies. A trilayer metamaterial absorber, composed of a metal structure/dielectric spacer/vanadium dioxide (VO2) ground plane, is shown to switch reversibly between reflective and absorptive states as a function of temperature. The VO2 lm, which changes its conductivity by four orders of magnitude across an insulator{metal transition, enables the switching by forming a resonant absorptive structure at high temperatures while being inactive at low temperatures. The fabricated metamaterial shows a modulation of the reflectivity levels of 58% at a frequency of 22.5 THz and 57% at a frequency of 34.5 THz. Chapter VI explains the W doped VO2 thin films synthesized by UN-SPACM. Morphology of the thin films was found to be consisting of globular and porous nanoparticles having size 20 nm. Transition temperature decreased with the addition of W. 1.8 at. %W doping in VO2 transition temperature has reduced upto 25 oC. It is noted that W-doping in the pro-cess of reducing the transition temperature, alters the local structure and also increases room temperature carrier concentration. The presence of W, as was seen in Chapter IV, altered V4+-V4+ bonds and introduced V3+. W was found to be in W6+ state suggesting W addition increased the carrier concentration. Hall Effect measurements suggested the increased carrier con-centration. The roughness of the synthesized films were very high for them to be of de-vice quality, despite encouraging results obtained by electrical measurements. Hence in order to further improve the smoothness and thereby the optical quality of thin films, Chemical Vapour Deposition (CVD) is employed. Chapter VII outlines the effect of processing parameters and post pro-cessing annealing on the semiconductor-metallic transition of VO2. Here in this chapter, the influence of substrate temperature on the SMT properties of VO2 is explored. At different substrate temperatures, the percentage of phase fraction of V in V3+, 4+ and V5+ differed. Besides, the morphology also varied with substrate temperatures. Similarly it is observed that with annealing the VO2 film deposited on glass substrates, SMT properties enhanced which was attributed to filling out of oxygen vacancies. Si based substrates and non-Si based substrates were used for depositing VO2 thin films by CVD. Their temperature coefficient of resistance and SMT properties were studied in order to understand their potential in bolometer and thermal to optical valve based applications. Chapter VIII involves the study of VO2 thin films for thermal to optical valves. ITO coated glass substrates were used for the purpose. Thin films were deposited by both UNSPACM and CVD. It was observed that the reflectivity pro les of the films synthesized by the above said methods were very different. Hence in the process of understanding the huge difference in the reflectivity pro les, classical harmonic oscillator, Lorentzian model was employed to t the experimental data at room temperature whereas Drude-Lorentzian model was used to t the data at higher temperature (at 100 oC- after transition). With this fitting plasma frequencies of the CVD films were calculated. It was observed that defect chemistry of films synthesized by these methods were different. In order to further improve the smoothness of the films, microwave method was proposed in Chapter IX. The preliminary results showed the presence of uniform spheres and 3 D hierarchical structures of VO2 consisting of nanorods. This was extended to deposit VO2 thin films on ITO. DSC and Infrared reflectance pro le of VO2 nanopowder suggested the phase transition. Chapter X summarizes the work done for the thesis and provides insights to the applications and to the future work. The work reported in this thesis has been carried out by the candidate as part of the Ph.D.program. She hopes that this would constitute a worth-while contribution towards development of VO2 thin film technology and its challenges for reliable infrared device applications.