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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
651

Células solares de silício de alto rendimento: otimizações teóricas e implementações experimentais utilizando processos de baixo custo. / High efficiency silicon solar cells: theoretical optimizations and experimental developments using low cost processes.

Stem, Nair 24 October 2007 (has links)
O trabalho realizado nesta tese esteve apoiado em dois objetivos principais. O primeiro centrado na otimização das etapas e processos de fabricação de células solares de silício de alto rendimento envolvendo redução de custos. O segundo objetivo foi direcionado na implementação de células solares eficientes e não dependentes do armadilhamento de impurezas através da difusão de alumínio. Para levar a cabo estes objetivos de forma planejada, o trabalho dividiu-se em otimizações teóricas e implementações experimentais. As otimizações teóricas foram realizadas utilizando dois programas: um programa desenvolvido (simulacell.pas) e implementado no próprio LME (versão 2), e o outro adquirido comercialmente, PC1D. De acordo com os resultados obtidos em estruturas completas n+p e n++n+p foi possível concluir que tanto as estruturas formadas através de emissores homogêneos como as obtidas utilizando emissores duplamente difundidos permitem alcançar eficiências elevadas, 25,5% a 26,0%, respectivamente, em um amplo intervalo de espessuras e concentrações superficiais de dopantes. No que tange aos desenvolvimentos experimentais, este trabalho se inicia com o desenvolvimento de um processo simplificado de baixo custo, em células solares de silício Cz de baixa resistividade com estrutura n+pp+, tipo \"mesa\". Este processo simplificado também está baseado na difusão de fósforo e alumínio (P/Al), utilizando gases industriais e reagentes químicos de grau \"para análise\", como uma transposição do processo de fabricação anteriormente desenvolvido no LME-EPUSP em substratos de silício FZ utilizando tecnologia planar. A célula solar mais representativa do processo implementado, A-16-1, permitiu atingir eficiências no entorno de 17%. As implementações experimentais visaram inicialmente o desenvolvimento de um procedimento visando à qualificação de materiais de partida (silício), utilizando a técnica de decaimento fotocondutivo (PCD) através de dois procedimentos de passivação de superfícies; oxidações térmicas e difusões suaves de fósforo. Posteriormente, utilizando o sistema PCD, novas otimizações dos emissores de tipo n+ homogêneos e regiões de tipo p foram realizadas, seguidos por oxidações térmicas passivadoras hidrogenadas, preservando-se o tempo de vida do volume em valores elevados (aproximadamente 1ms, após a realização de todas as etapas térmicas). Estes resultados qualificam o silício e os materiais de consumo utilizados, assim como, o novo processo de fabricação desenvolvido. Esta técnica também permitiu qualificar os emissores com perfil Gaussianos processados, atingindo valores da ordem de 45fA/cm2 para densidades de recombinação em estruturas n+pn+. Desenvolveram-se também estruturas n+p em materiais Cz de baixa resistividade 2-3W.cm de dois diferentes fabricantes, e silício FZ com 0,5W.cm. Pôde ser comprovada a qualidade das etapas que compõem o processo completo otimizado tendo-se obtido tensões de circuito aberto-implícitas de 652,4mV (Si-Cz fabricante 1) e 662,6mV (Si-Cz fabricante 2), e 670,8mV (FZ). De acordo com simulações realizadas utilizando parâmetros habituais de dispositivos do próprio LME, estas tensões, quando associadas a um conjunto óptico frontal típico das células solares de alto rendimento do LME (texturização química aleatória e filme de SiO2), permitirão atingir valores entre 19% - 20%. Entretanto, utilizando texturização e camada dupla torna-se plausível atingir o marco de 21% de rendimento, ultrapassando assim a barreira dos 17% (recorde nacional), e comprovando a potencialidade da infra-estrutura deste laboratório para o desenvolvimento de células solares não dependentes do efeito do armadilhamento de impurezas através da difusão de alumínio. / The work developed at this thesis has been based on two main objectives. First, it was focused on the optimization of the steps and processes for the fabrication of high efficiency solar cells, reducing production costs. The latter objective was directed to develop solar cells that were efficient and non-dependent on impurities gettering performed through the aluminum diffusion. In order to attend the planned objectives the work was divided into the theoretical objectives and experimental developments. The theoretical optimizations were performed using two different program codes: one was developed at LME (simulacell.pas), being upgraded afterwards (version 2); and the other was acquired commercially, the PC1D. According to the obtained results in complete structures n+p and n++n+p, it was possible to conclude that the homogeneous and double diffused emitter structures can provide high efficiencies, from 25,5% to 26,0%, respectively, for a wide range of thicknesses and surface doping levels. Concerning the experimental developments, this work starts with a low cost simplified process, using Cz silicon solar cells with low base resistivity and the structure n+pp+, \"mesa\" type. This simplified process was also based on the phosphorus/ aluminum diffusion (P/Al), using industrial gases and for analysis grade chemical reagents, as a fabrication process transposition of the process previously developed at LME-EPUSP using silicon substrates with planar technology. The most representative solar cells of the implemented process, A-16-1, provided about a 17% efficiency. The experimental implementations aimed the development of procedure for starting material (silicon) qualification, by using the photoconductive decay technique (PCD) with two surface passivation procedures: thermal oxidation and light phosphorus diffusion. Later, using PCD system, new optimizations of n+ homogeneous emitters and p-type region were performed, followed by passivating thermal oxidations with hydrogenation, maintaining the volume lifetime at high values (approximately 1ms, after each thermal step). These results qualified the used silicon and the consumer materials, as well the new fabrication process developed. This technique has also allowed qualifying the processed Gaussian profile emitters, providing values about 45fA/cm2 for the recombination current density in n+pp+ structures. N+p structures were also developed using Cz silicon with low resistivity 2- 3W.cm of two different manufacturers and FZ with 0.5W.cm. It could be proved the quality of the steps of a complete optimized process resulting implicit open circuit voltages of 652.4mV (Cz silicon - manufacturer type 1), 662.6mV (Cz silicon - manufacturer type 2), and 670.8mV (FZ silicon). According to the theoretical simulations performed using the usual parameters of devices processed at LME (random chemical texturization and SiO2 film), efficiencies between 19%-20% can be reached. However, using a random texturization and a double layer anti-reflection system, a 21% efficiency becomes possible, surpassing the 17% barrier (national record), and proving the potentiality of this laboratory facility for the development of solar cells non-dependent on impurity gettering through the aluminum diffusion.
652

Structure des fragments de fission de masse A = 100 - 110 : mesures de temps de vie et analyses en champ moyen et au-delà / Structure of fission fragments of mass A = 100 - 110 : lifetime measurements and mean field and beyond mean field analysis

Grente, Lucie 24 September 2014 (has links)
Les noyaux riches en neutrons de masse A=100-110 constituent une région de grand intérêt pour l'étude de la structure nucléaire loin de la stabilité. De précédentes études de cette région de masse ont déjà révélé la complexité de l'évolution de la collectivité et de la déformation dans les chaînes isotopiques de Zr, Mo, Ru et Pd. Afin d'étendre les données expérimentales sur la collectivité à des états de plus haut spin et à des noyaux plus riches en neutrons, des temps de vie d'états excités ont été mesurés dans des noyaux produits par une réaction de fusion-fission en cinématique inverse au GANIL. Les fragments de fission étaient séparés et identifiés en A et Z grâce au spectromètre magnétique de grande acceptance VAMOS tandis que le rayonnement gamma était détecté dans l'ensemble de détecteurs germanium EXOGAM. Environ vingt temps de vie d'états 2+, 4+ et 6+ ont été extraits à l'aide du plunger de Cologne. Cette expérience représente la première mesure RDDS dans des fragments de fission identifiés évènement par évènement à la fois en A et Z.Cette étude des noyaux de masse A=100-110 est complétée par des calculs auto-cohérents de champ moyen et au-delà avec la force de Gogny (D1S). La structure des états fondamentaux et excités est décrite dans le cadre du modèle de Hartree-Fock-Bogoliubov avec des contraintes sur les déformations axiale et triaxiale. Les excitations individuelles sont étudiées par des calculs bloqués et les états de haut spin sont décrits dans l'approximation du champ tournant. Enfin, la méthode de la coordonnée génératrice approchée par un hamiltonien collectif en cinq dimensions (5DCH) est appliquée aux états collectifs de basse énergie. Les résultats sont comparés aux mesures de la collectivité. / Neutron-rich nuclei of mass A=100-110 are of great interest for the study of nuclear structure far from stability. Previous experimental and theoretical studies suggest a complex evolution of deformation and collectivity in the isotopic chains of Zr, Mo, Ru and Pd.In order to extend information on the evolution of the collectivity towards higher spin states and more neutron-rich nuclei, lifetimes of excited states were measured in nuclei produced through a fusion-fission reaction in inverse kinematic at GANIL. Fission fragments were separated and identified in both A and Z with the high acceptance magnetic spectrometer VAMOS while the EXOGAM germanium detectors array was used for the coincident gamma-ray detection. Lifetimes of about twenty excited states were extracted using the plunger device of Cologne. This is the first RDDS measurement on fission fragments which are identified in A and Z on an event-by-event basis. The study of this mass region is completed by theoretical calculations using self consistent mean field and beyond mean field methods implemented with the Gogny force (D1S). The structure of the ground states and the excited states is described with Hartree-Fock-Bogoliubov calculations with constraints placed on the axial and triaxial deformations. Individual excitations are investigated through blocking calculations and the high spin states are studied through cranking calculations. Finally, an approximated generator coordinate method (GCM+GOA) using the 5DCH hamiltonian is used to describe the low energy collective states and to interpret the experimental evolution of the collectivity.
653

Propriétés mécaniques et dégradation des élastomères EPDM chargés ATH / Mechanical properties and degradation of ATH filled EPDM

De Almeida, André 19 May 2014 (has links)
Les EPDM (Ethylène Propylène Diène Monomère) sont employés comme isolants des câbles électriques des centrales nucléaires. En raison de l’environnement radioactif, ils se dégradent plus rapidement qu’en environnement classique. La détermination de leur durée de vie est donc un enjeu industriel important. Pour y parvenir, ce travail a d’abord consisté à déterminer l’influence de la composition des EPDM sur leurs cinétiques de dégradation. Ainsi, deux EPDM de composition chimique différente ont été irradiés sous rayonnement en présence d’oxygène. Les suivis de la fraction soluble et de la densité de chaines actives en fonction de la dose, ont permis de mettre en évidence une dégradation par réticulation et coupures de chaines. A partir de modèles statistiques, les cinétiques de ces deux processus ont pu être estimées : la réticulation dépend de la proportion en ENB résiduels tandis que les coupures de chaines sont indépendantes de la composition chimique et du degré de réticulation initial. De plus, au - delà d’une certaine dose, les nœuds de réticulation semblent progressivement détruits. Nous nous sommes ensuite intéressés aux conséquences de l’irradiation sur les propriétés mécaniques et ce, d’abord à 80°C, pour s’affranchir de la présence de cristallites. Si dans tous les cas, l’irradiation conduit à une décroissance de la contrainte à la rupture, nos matériaux montrent une déformation à rupture qui augmente avec la dose contrairement aux matériaux de Planès et al. Pour s’affranchir du rôle des hétérogénéités sur l’initiation de fissure, les propriétés mécaniques d’éprouvettes entaillées ont ensuite été étudiées. L’énergie de déchirement est corrélée à l’énergie de rupture des matériaux entaillés et peut être décrite par le modèle de Lake et Thomas, à condition de prendre en compte la longueur réelle entre nœuds de réticulation des matériaux irradiés. Aussi, les propriétés en rupture de tous les matériaux sont améliorées quand ils sont étudiés à 25°C et la présence de cristallites masque les conséquences de la dégradation ; cet effet est ici très marqué en raison d’une importante chimie - cristallisation. Des EPDM chargés ATH ont alors été étudiés. Nos résultats confirment une accélération de la dégradation par les ATH, dépendant de la surface spécifique des charges. La compréhension des propriétés en rupture des composites s’avère complexe car la rupture peut être entrainée par divers processus en compétition. L’évolution des propriétés mécaniques des composites testés à 25°C est, comme pour la matrice pure, dépendante de l’évolution de la cristallinité et des propriétés de la phase amorphe. Enfin, ce travail remet en cause la pertinence des critères de durée de vie actuellement utilisés dans l’industrie. Les énergies de rupture étant plus directement corrélées aux paramètres microstructuraux, ne faudrait-il pas plutôt considérer ce paramètre comme critère? / EPDM (EThylene Propylene Diene Monomer) are used as insulation for electrical cables in nuclear plants. Because of the radiative environment, the degradation of these cables is accelerated and a strong industrial challenge consists in the prediction of the cables lifetime. To address this crucial industrial concern, we first looked into the influence of the chemical composition of EPDM on their kinetics of degradation. To do so, two EPDM with different chemical compositions have been irradiated under radiations and in the presence of oxygen. The soluble fraction and the active chain density have been monitored as a function of the irradiation dose, and revealed the degradation by cross-linking and chain scissions. Furthermore, the kinetics of these mechanisms have been estimated based on statistical models: the cross-linking kinetics depends on the residual ENB content while the chain scission kinetics vary neither with the chemical composition nor the initial cross-linking degree. Moreover, beyond an irradiation dose, the cross-links are progressively broken. The mechanical performances were then studied at 80°C to prevent crystallinity. If the irradiation induces a decrease of the stress at break, the materials show an increase of the strain at break conversely to the EPDM systems studied by Planès et al. The mechanical properties of notched samples have then been employed in order prevent heterogeneities driven crack initiation. The tearing energy measured was correlated with the failure energy of notched samples andcan be described by the Lake and Thomas model with account for the real length between cross-links. The same study has then been performed at 25°C where the properties at break are seen to improve. Such improvements despite irradiation confirm that crystallites attenuate the degradation. This effect is more pronounced for the current set of materials because of a strong chemi-crystallisation. The addition of ATH fillers has been studied as well, showing an acceleration of the matrix degradation with the specific surface of the fillers. The understanding of the mechanical properties at break of filled materials seems complex because the failure can be obtained by various competing processes. Nevertheless, the matrix chemical nature can be mentioned as an important factor since the difference between the matrix mechanical properties and the matrix-filler interface properties will trigger the creation of macro-defects at the origin of failure. As for the neat matrix, the evolution of the composites mechanical properties tested at 25°C depends on the evolutions of both the crystallinity and the amorphous phase. More generally, this work questions the relevance of the actual lifetime criterion used in the industry. The energies at break are more directly correlated to the microstructural parameters and thus could correspond to a relevant criteria for predicting these systems lifetime.
654

Photoelectron Spectroscopy on Atoms, Molecules and Clusters : The Geometric and Electronic Structure Studied by Synchrotron Radiation and Lasers

Rander, Torbjörn January 2007 (has links)
<p>Atoms, molecules and clusters all constitute building blocks of macroscopic matter. Therefore, understanding the electronic and geometrical properties of such systems is the key to understanding the properties of solid state objects.</p><p>In this thesis, some atomic, molecular and cluster systems (clusters of O<sub>2</sub>, CH<sub>3</sub>Br, Ar/O<sub>2</sub>, Ar/Xe and Ar/Kr; dimers of Na; Na and K atoms) have been investigated using synchrotron radiation, and in the two last instances, laser light. We have performed x-ray photoelectron spectroscopy (XPS) on all of these systems. We have also applied ultraviolet photoelectron spectroscopy (UPS), resonant Auger spectroscopy (RAS) and near-edge x-ray absorption spectroscopy (NEXAFS) to study many of the systems. Calculations using <i>ab initio</i> methods, namely density functional theory (DFT) and Møller-Plesset perturbation theory (MP), were employed for electronic structure calculations. The geometrical structure was studied using a combination of <i>ab initio</i> and molecular dynamics (MD) methods.</p><p>Results on the dissociation behavior of CH<sub>3</sub>Br and O<sub>2</sub> molecules in clusters are presented. The dissociation of the Na<sub>2</sub> molecule has been characterized and the molecular field splitting of the Na 2<i>p</i> level in the dimer has been measured. The molecular field splitting of the CH<sub>3</sub>Br 3<i>d</i> level has been measured and the structure of CH<sub>3</sub>Br clusters has been determined to be similar to the structure of the bulk solid. The diffusion behavior of O<sub>2</sub>, Kr and Xe on large Ar clusters, as a function of doping rate, has been investigated. The shake-down process has been observed from excited states of Na and K. Laser excited Na atoms have been shown to be magnetically aligned. The shake-down process was used to characterize the origin of various final states that can be observed in the spectrum of ground-state K.</p>
655

Photoelectron Spectroscopy on Atoms, Molecules and Clusters : The Geometric and Electronic Structure Studied by Synchrotron Radiation and Lasers

Rander, Torbjörn January 2007 (has links)
Atoms, molecules and clusters all constitute building blocks of macroscopic matter. Therefore, understanding the electronic and geometrical properties of such systems is the key to understanding the properties of solid state objects. In this thesis, some atomic, molecular and cluster systems (clusters of O2, CH3Br, Ar/O2, Ar/Xe and Ar/Kr; dimers of Na; Na and K atoms) have been investigated using synchrotron radiation, and in the two last instances, laser light. We have performed x-ray photoelectron spectroscopy (XPS) on all of these systems. We have also applied ultraviolet photoelectron spectroscopy (UPS), resonant Auger spectroscopy (RAS) and near-edge x-ray absorption spectroscopy (NEXAFS) to study many of the systems. Calculations using ab initio methods, namely density functional theory (DFT) and Møller-Plesset perturbation theory (MP), were employed for electronic structure calculations. The geometrical structure was studied using a combination of ab initio and molecular dynamics (MD) methods. Results on the dissociation behavior of CH3Br and O2 molecules in clusters are presented. The dissociation of the Na2 molecule has been characterized and the molecular field splitting of the Na 2p level in the dimer has been measured. The molecular field splitting of the CH3Br 3d level has been measured and the structure of CH3Br clusters has been determined to be similar to the structure of the bulk solid. The diffusion behavior of O2, Kr and Xe on large Ar clusters, as a function of doping rate, has been investigated. The shake-down process has been observed from excited states of Na and K. Laser excited Na atoms have been shown to be magnetically aligned. The shake-down process was used to characterize the origin of various final states that can be observed in the spectrum of ground-state K.
656

La Aplicación del Valor de Vida del Cliente en la Gestión de la Relación con el Distribuidor en Empresas de Consumo Masivo de Productos Empaquetados de Lima, Perú. Un Estudio de Casos Múltiple

Wakabayashi Muroya, José Luis 21 January 2011 (has links)
La gestió de la relació amb el client (CRM) és el procés en què es creen relacions amb els clients i altres actors al llarg de les seves vides. Així, a la base d'aquest procés hi ha el concepte de CLV, conegut com el valor del cicle de vida del client (customer lifetime value), que permet calcular tant el valor net del client com la seva rendibilitat per a l'empresa. Aquesta tesi destaca el fet que el màrqueting teòric ha desenvolupat diferents camps d'aplicació per afrontar el procés de CRM. Un d'aquests, que cada vegada és més important, és la gestió de la relació amb el canal de distribució. Aquesta tesi és un intent per cobrir el buit que hi ha en la recerca de màrqueting sobre aquest tema i esbrinar el veritable paper del CLV en un context concret d'aplicació: les empreses de consum de masses de Lima i els seus distribuïdors. Aquest camp resta gairebé inexplorat i ha estat poc investigat, malgrat que el procés de CMR en el mercat de masses i la relació amb els distribuïdors constitueixen importants camps d'aplicació per al CLV. A partir de l'anàlisi de casos de tres diferents empreses peruanes, mitjançant entrevistes i observacions realitzades al seu personal, aquesta tesi investiga l'aplicació del CLV com a concepte clau i com a eina de mesurament en els processos de gestió de la relació (CRM) amb els seus canals de distribució o intermediaris. L'estudi s'ha dut a terme al Perú perquè aquest país té unes característiques similars als altres països llatinoamericans i la regió gairebé no disposa de cap recerca en CMR. Per això, aquest treball espera proporcionar informació significativa sobre l'aplicació del concepte dogmàtic de CMR. La tesi argüeix que, malgrat que l'evolució cap a una aproximació relacional del màrqueting s'ha estès, la pràctica encara difereix de la teoria en molts mercats, com s'ha observat a les tres empreses estudiades. Per aquest motiu, aquest treball de recerca pot constituir un punt de partida per a investigacions més profundes en la matèria. / La gestión de la relación con el cliente (CRM) es el proceso en el que se crean relaciones con los clientes y otros actores a lo largo de sus vidas. Así, en la base de ese proceso se encuentra el concepto del CLV, conocido como valor de ciclo de vida del cliente (customer lifetime value), que permite calcular tanto el valor neto del cliente y su rentabilidad para la empresa. Esta tesis pone resalta el hecho de que el marketing teórico ha desarrollado diferentes campos de aplicación para encarar el proceso de CRM. Una de estas, y cada vez más importante, es la gestión de relación con el canal de distribución. Además, puesto que este tema constituye un vacío en la investigación de marketing, esta tesis constituye un intento para reducirlo y averiguar el verdadero papel del CLV en un contexto particular de aplicación: las empresas de consumo masivo de Lima y sus distribuidores. Este campo permanece casi inexplorado y cuenta con escasa investigación a pesar de que el proceso de CMR en el mercado masivo y la relación con los distribuidores constituyen importantes campos de aplicación para el CLV. Mediante el análisis de casos de tres diferentes empresas peruanas, mediante entrevistas y observaciones realizadas al personal de las mismas, esta tesis investiga la aplicación del CLV como concepto clave y como herramienta de medición en los procesos de gestión de la relación (CRM) con sus canales de distribución o intermediarios. Este estudio se llevó a cabo en Perú porque este país comparte características similares con el resto de países latinoamericanos y esta región casi no cuenta con investigación en CMR. Por ello este trabajo espera brindar información significativa sobre la aplicación del concepto dogmatico de CMR. Esta tesis arguye que a pesar de que la evolución hacia una aproximación relacional del marketing se ha extendido, todavía la práctica difiere de la teoría en muchos mercados, como se ha observado en las tres compañías estudiadas, por tal razón el presente trabajo de investigación puede constituir un punto de partida para investigaciones más profundas al respecto. / The customer relationship management (CRM) is the process where relationships with customers and other actors are created throughout their lifecycle. Therefore, in the very foundations of this process is CLV, a key concept known as well as customer lifetime value, that allows estimating not only the customer net value over a long period of time , but also his profitability for the company. This dissertation remarks the fact that theoretical Marketing has developed different fields of application to face the complex process of CRM. One of them, in increasing importance, is the CRM with the distribution channel. Since this issue means a gap in marketing research, this dissertation constitutes an attempt to reduce it and find out the very role of CLV when CRM takes place in a particular context of application: massive consume companies from Lima and their distributors. This field is almost unexplored and has little research despite the fact that CRM process in the massive market and the relationship with distributors constitute important fields of application for the CLV. Through an analysis of three cases of different Peruvian companies, by interviewing their staff, this dissertation investigates the application of CLV as a key concept and as a measuring tool for CRM process with the distribution channel or intermediaries. This study took place in Peru because this country has similar characteristics with the rest of Latin American countries and this region has almost no research in CRM process. That is why this dissertation expects to add significant information about the application of the dogmatic concept of CRM. This dissertation argues that despite the fact that an evolutional shift to a Marketing relationship approach is extended around the world, theory and practice still differs each other in a number of markets, as it is observed in the companies selected to this research. Thus this study could be the starting point of more and deeper research about it.
657

Solvent–Solute Interaction : Studied by Synchrotron Radiation Based Photo and Auger Electron Spectroscopies

Pokapanich, Wandared January 2011 (has links)
Aqueous solutions were studied using photoelectron and Auger spectroscopy, based on synchrotron radiation and a liquid micro-jet setup. By varying the photon energy in photoelectron spectra, we depth profiled an aqueous tetrabutylammonium iodide (TBAI) solution. Assuming uniform angular emission from the core levels, we found that the TBA+ ions were oriented at the surface with the hydrophobic butyl arms sticking into the liquid. We investigated the association between ions and their neighbors in aqueous solutions by studying the electronic decay after core ionization. The (2p)−1 decay of solvated K+ and Ca2+ ions was studied. The main features in the investigated decay spectra corresponded to two-hole final states localized on the ions. The spectra also showed additional features, related to delocalized two-hole final states with vacancies on a cation and a neighboring water molecule. These two processes compete, and by comparing relative intensities and using the known rate for the localized decay, we determined the time-scale for the delocalized process for the two ions. We compared to delocalized electronic decay processes in Na+, Mg2+, and Al3+, and found that they were slower in K+ and Ca2+, due to different internal decay mechanisms of the ions, as well as external differences in the ion-solute distances and interactions. In the O 1s Auger spectra of aqueous metal halide solutions, we observed features related to delocalized two-hole final states with vacancies on a water molecule and a neighboring solvated anion. The relative intensity of these feature indicated that the strength of the interaction between the halide ions and water correlated with ionic size. The delocalized decay was also used to investigate contact ion pair formation in high concentrated potassium halide solutions, but no concrete evidence of contact ion pairs was observed. / Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 726
658

Innovative NIR fluorescent probes for an improved tumor detection in vivo / Innovative Nahinfrarot (NIR) Fluoreszenzproben für eine verbesserte Tumordetektion in vivo

Mathejczyk, Julia Eva 15 December 2011 (has links)
No description available.
659

プラズマプロセシング用SiH4のラジカル非発光種に関する研究

後藤, 俊夫, 稲葉, 成基, 羽根, 一博, 河野, 明広 03 1900 (has links)
科学研究費補助金 研究種目:一般研究(B) 課題番号:17520427 研究代表者:後藤 俊夫 研究期間:1985-1986年度
660

Optimization of rectifiers for aviation regarding power density and reliability / Optimierung von Gleichrichtern für die Luftfahrt unter Berücksichtigung von Leistungsdichte und Zuverlässigkeit

Liebig, Sebastian 01 June 2015 (has links) (PDF)
The intentions of the so-called "More Electrical Aircraft" (MEA) are higher efficiency and lower weight. A main topic here is the application of electrical instead of hydraulical, pneumatical and mechanical systems. The necessary power electronic devices have intermediate DC-links, which are typically supplied by a three-phase system with active B6 and passive B12 rectifiers. A possible alternative is the B6 diode bridge in combination with an active power filter (APF). Due to the parallel arrangement, the APF offers a higher power density and is able to compensate for harmonics from several devices. The use of the diode bridge rectifier alone is not permitted due to the highly distorted phase current. The following investigations are dealing with the development of an active power filter for a three-phase supply with variable frequency from 360 to 800 Hz. All relevant components such as inductors, EMC-filters, power modules and DC-link capacitor are designed. A particular focus is put on the customized power module with SiC-MOSFETs and SiC-diodes, which is characterized electrically and thermally. The maximum supply frequency slope has a value of 50 Hz/ms, which requires a high dynamic and robustness on the control algorithm. Furthermore, the content of 5th and 7th harmonics must be reduced to less than 2 %, which demands a high accuracy. To cope with both requirements, a two-stage filter algorithm is developed and implemented in two independent signal processors. Simulations and laboratory experiments confirm the performance and robustness of the control algorithm. This work comprehensively presents the design of aerospace rectifiers. The results were published in conferences and patents. / Hauptziele des sogenannten "More Electrical Aircraft" (MEA) sind Effizienzerhöhung und Gewichtseinsparung. Ein Schwerpunkt hierbei ist die Nutzung von elektrischen statt hydraulischen, pneumatischen und mechanischen Systemen. Die notwendigen Leistungselektroniken haben DC-Zwischenkreise, welche mittels aktiven B6 und passiven B12 Gleichrichtern aus dem Dreiphasennetz gespeist werden. Eine mögliche Alternative ist die B6 Diodenbrücke in Kombination mit einem aktiven Netzfilter, welcher aufgrund der parallelen Anordnung eine höhere Leistungsdichte aufweist und darüber hinaus mehrere Geräte gleichzeitig entstören kann. Die alleinige Nutzung einer Diodenbrücke ist aufgrund des hohen Anteils von Stromharmonischen nicht zulässig. Diese Arbeit beschäftigt sich mit der Entwicklung eines aktiven Filters für ein Dreiphasensystem mit variabler Frequenz von 360 bis 800 Hz. Es werden alle relevanten Bauteile wie Induktivitäten, EMV-Filter, Leistungsmodule und Zwischenkreiskondensator ausgelegt. Besonderes Augenmerk liegt auf dem kundenspezifischen Modul mit SiC-Dioden und SiCMOSFETs, welches vollständig elektrisch und thermisch charakterisiert wird. Die Änderung der Netzfrequenz beträgt bis zu 50 Hz/ms, was eine hohe Dynamik und Robustheit von der Filterregelung verlangt. Weiterhin ist im statischen Fall eine hohe Genauigkeit gefordert, da die 5. und 7. Harmonische auf unter 2% geregelt werden müssen. Um beiden Anforderungen gerecht zu werden, wird ein zweistufiger Regelungsalgorithmus entwickelt der auf zwei digitalen Signalprozessoren implementiert wird. Simulationen und Labormessungen bestätigen die Robustheit des Regelungskonzeptes. Diese Arbeit stellt umfassend die Entwicklung von Luftfahrtgleichrichtern dar. Die Ergebnisse wurden in Konferenzen und Patenten veröffentlicht.

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