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Sharma, Amit. "Materials chemistry and magnetoresistance of Sr₂FeMoO₆." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415224.
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Zegmout, Hanae. "Echantillonneur opto-electronique femto seconde." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAT084.
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Dans un monde de plus en plus connecté, il devient indispensable de trouver des moyens d’augmenter le débit d’informations qu’il est possible de véhiculer et de traiter. Ce besoin impose aux ingénieurs des contraintes plus serrées en termes de bande passante et de fréquence d’horloge des circuits qu’ils conçoivent.Or, les circuits d’horloge en microélectroniques sont limités par leur performance en termes de stabilité de la période d’horloge, i.e., en termes de « gigue d’horloge » ; cette limitation provient du bruit inhérent au circuit des horloges et rend donc le signal échantillonné inexploitable.Un moyen de se libérer de cette contrainte pourrait être de passer par la photonique intégrée. En effet, les horloges optiques, i.e les lasers pulsés, présentent des performances très intéressantes en termes de stabilité ou de gigue en comparaison avec les horloges en microélectroniques: les gigues des horloges optiques sont cinq fois plus faibles que la plus faible gigue d’horloge électronique citée dans la littérature.L’idée principale de cette thèse est de concevoir un circuit d’échantillonnage qui utilise les pulses du laser comme horloge et qui échantillonne un signal électronique. La brique de base du circuit en question est un photoconducteur en Germanium : une résistance en Germanium dont la résistivité varie selon la puissance du signal optique qu’elle reçoit du laser pulsé. Le photoconducteur dans ce cas précis jour le rôle d’un interrupteur piloté par le laser, et connecte l’entrée RF à la capacité d’échantillonnage. Quand l’interrupteur reçoit un pulse de lumière sa résistance chute et le signal RF peut être copié vers la capacité. Dès que le pulse de lumière s’arrête, le photoconducteur en Germanium retrouve sa résistance initiale et déconnecte ainsi l’entrée RF de la capacité qui contient le signal échantillonné.Cette thèse se propose d’étudier la faisabilité d’un tel circuit et la possibilité d’exploiter la performance des lasers en termes de stabilité de l’horloge dans l’échantillonnage d’un signal électrique.Dans le cadre de la thèse, nous avons essayé d’implémenter le circuit de base présenté auparavant et avons rencontré plusieurs défis. D’abord, les valeurs des résistances Off du photoconducteur n’étaient pas assez élevées pour permettre de déconnecter entièrement le signal RF de la capacité d’échantillonnage. Cela est dû à la présence d’un dopage résiduel lié au procédé de fabrication des photoconducteurs. L’utilisation du Germanium implique également que le passage de l’état On à l’état Off du photoconducteur n’est pas instantané, mais est fonction de la durée de vie des porteurs de charge créés suite à l’exposition aux pulses de lumière (de l’ordre de la nanoseconde).Nous avons contourné ces problèmes en utilisant trois méthodes : une nouvelle géométrie des photoconducteurs en Germanium qui permet de maximiser le rapport Roff/Ron (géométrie brevetée), un contre-dopage pour augmenter la résistivité du matériau et finalement un circuit électronique qui permet de re-échantillonner le signal en utilisant une horloge photonique basée sur les pulses du laser. Nous avons également exploré la possibilité de concevoir des horloges photoniques qui présentent une très faible valeur de gigue et dont la longueur du pulse peut être modifiée de manière indépendante de la longueur du pulse laser utilisé pour les générerAs the world becomes more and more connected, the need for higher data throughput becomes increasingly urgent. This implied more creativity from circuit designers to come up with higher bandwidth circuits and faster pace clocks to drive them.However, the traditional microelectronics clock circuits fail short to fulfill the ever-increasing need for higher sampling frequencies because of their inherent noise. The latter renders the sampled data altogether unusable and therefore hinders the efforts towards higher streams of data.Integrated photonics, the optics alternative to microelectronics, may bring an end to this problem. Indeed, when it comes to pulsed lasers, a not that new technology, the optical pulses clocking features a very low noise compared to its microelectronics counterpart, i.e a jitter that is five folds lower than the best literature microelectronics clock.The main idea of this thesis is to design a sampling circuit that uses the laser pulses as a clock, but samples an electronic signal. This circuit design is mainly based on the use of a Germanium photoconductor, i.e, a Germanium resistor that changes its resistance according to the value of the optical signal it receives. This photoconductor plays then the role of a clocked switch and connects the RF input signal to the hold capacitor. When the switch receives a pulse of light, its resistance drops and the signal can be copied to the capacitor, and once the pulse of light is over, the Germanium photoconductor recovers its first resistance value and the input signal node is disconnected from the capacitor that holds the sampled signal.The aim of this thesis is to study the feasibility of such a design and whether or not it allows taking advantage of the very low jitter value of the laser. Within the thesis, we tried to implement the up said design and stumbled upon many challenges. First, the values of the off switch resistance were not high enough to disconnect the hold capacitor from the input node due to the low resistivity of the used Germanium (residual doping). The Germanium implies also that the switching from one resistance value to another is not instantaneous but rather as long as the photo-generated carriers exist, which lasts for at least a nanosecond. We resolved these problems using three methods: a novel geometry of Germanium photoconductors that allows for high Roff/Ron ratios (patented geometry), a counter-doping to increase the resistivity of the material and finally, a re-sampling circuit driven by a photonic clock based on the laser pulses. We also explored the possibility of making very steep-edged clocks with customizable pulse lengths based on the laser pulses
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Karantzoulis, Nikolaos. "Development and implementation of inelastic material models for use in FEMDEM numerical methods with applications." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/58998.
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The combined Finite–Discrete Element Method (FEMDEM) is one of the most versatile numerical frameworks for the mechanical analysis of multi-body industrial applications. Currently, the inclusion of only elastic and brittle material models limits the problems that can be realistically simulated. This new work focuses on expanding the capabilities of existing FEMDEM codes in order to include inelastic material models successfully. After describing and implementing the appropriate theoretical and numerical framework for elasto-plasticity, a thorough numerical verification analysis is presented. Test cases, varying from simple one-dimensional quasi-static problems through to fully three-dimensional impact analysis, are explored to illustrate the stability, accuracy and robustness of the inelastic behaviour implemented. The extension of this plasticity implementation to finite deformations is then discussed. The ability of the extended simulation tool to capture large strain non-linear phenomena is then numerically demonstrated with the successful analysis of two benchmark problems: (a) the high-speed impact of a copper rod against a wall; (b) the unconfined uniaxial compression of a cylinder with Mohr-Coulomb plasticity. To explore the potential range of the new model, a complete case study to simulate concrete crushing behaviour during an impact test is performed. A simple experimental setup is designed to investigate steel-to-concrete inelastic collisions focusing on the energy losses via the coefficient of restitution. The processed experimental results, combined with concrete-characterisation tests are used to calibrate a two-parameter Mohr-Coulomb material model via parametric numerical analysis. In order to overcome current limitations, a generalised piece-wise Drucker-Prager plasticity model to accommodate non-linear material plasticity behaviour is developed and corresponding return-mapping equations are discussed in detail. The foregoing extension to large strain plasticity of the in-house FEMDEM multi-body simulator, Solidity, is discussed in a more general context by reviewing recent FEMDEM development and application research being undertaken at Imperial College. Finally, this work is put into the overall context of the multi-physics research plans by providing preliminary analysis results for two industrial applications: (a) concrete armour units impacts, (b) powder compaction.
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Bernkopf, Jan. "Femto buňky v mobilních sítích nových generací." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-218943.
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This paper provides theoretical analysis of LTE network and Femto cells. Its presents their modulation and transition techniques, their performance and of course implementation of Femto cells into LTE macro-layer. It also describes potential risk of interference between LTE macro-layer and Femto cells and provides the way how to solve and simulate interference. Finally it states simulation and analysis of model situations.
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Montagono, Marie-Madeleine. "Ségrégation superficielle d'équilibre dans le système FeMoS." Aix-Marseille 3, 1993. http://www.theses.fr/1993AIX30057.
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La segregation est etudiee a l'aide de soufre radioactif et par spectroscopie auger dans du fer et des alliages de haute purete. La solubilite du soufre entre 650 et 880c a ete mesuree en utilisant du soufre radioactif. L'enthalpie de dissolution du soufre dans le fer pur a partir de 1/2 s#2 (vap) a ete evaluee a 48 kj mol##1. Le molybdene accroit beaucoup la solubilite et l'enthalpie d'interaction mo-s est de 63 kj mol##1. L'adsorption du soufre a ete realisee en utilisant des melanges h#2s/h#2 dont la composition etait fixee par l'equilibre avec du sulfure de cuivre radioactif. Cette technique etait indispensable pour controler le potentiel chimique tout en mesurant la quantite de soufre dissous pres de la surface. Des isothermes de segregation ont ete tracees pour le fer pur et pour l'alliage a 2% mo, a 800 et 880c et completees par des mesures a d'autres temperatures et pour d'autres compositions. L'examen des isothermes met en evidence un deplacement tres net des isothermes et un accroissement de la quantite maximale fixee qui augmentent avec la teneur en molybdene et diminuent quand la temperature augmente. Ces resultats sont confirmes par spectroscopie auger sans que l'on puisse situer le molybdene d'une facon certaine dans la couche superficielle. Ils sont la preuve indiscutable de l'existence d'une cosegregation entre le soufre et le molybdene. Les resultats sont discutes a l'aide du formalisme et des theories developpees pour la cosegregation
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Buckup, Tiago. "Dinâmica molecular investigada com pulsos de femto-segundos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2004. http://hdl.handle.net/10183/5482.
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Técnicas experimentais de óptica não-linear resolvidas no tempo são capazes, em diversas situações, de fornecer mais informações sobre a dinâmica e estrutura molecular do que técnicas sem nenhuma resolução temporal. Nesta tese investigou-se três sistemas com técnicas espectroscópicas resolvidas no tempo, utilizando pulsos ultra-curtos de um sistema LASER amplificado, baseado em cristal de Ti:Safira, e de amplificadores ópticos paramétricos. Para este estudo foram implementadas e analisadas quatro diferentes técnicas espectroscópicas resolvidas no tempo: Espalhamento Raman anti-Stokes Coerente (CARS), Espalhamento hiper-Rayleigh Resolvido no Tempo (TRHRS), Bombeio-Prova e Bombeio- Depleção-Prova. O três sistemas investigados apresentam um grau crescente de complexidade nas suas dinâmicas e interações com o meio. O primeiro dos sistemas estudados foi a dinâmica da molécula de H2 no regime de impacto, na presença de moléculas e átomos perturbadores (N2 e He). Foi possível determinar, pela primeira vez, coeficientes de alargamento para o ramo Q devido à colisões entre H2+H2 utilizando a técnica de CARS resolvido temporalmente, bem como novos coeficientes para o deslocamento das linhas. O emprego da mesma técnica em sistemas binários lançou mais luz sobre a possibilidade de existir alguma não-homogeneidade em tais tipos de colisões. O segundo experimento investigou a dinâmica de relaxação orientacional da acetonitrila em solução utilizando a nova técnica de TRHRS; esta foi desenvolvida e testada com sucesso pela primeira vez neste trabalho. Um modelamento teórico mostra que dentro do modelo de Debye para a difusão rotacional, tempos associados ao terceiro momento do tempo de difusão (τ3) e ao primeiro momento (τ1) devem ser observados. Os resultados experimentais para a acetonitrila apresentam um decaimento consistente com este modelo (τ3~850 fs), concordando também com valores derivados de resultados experimentais e teóricos obtidos por outros métodos. Além disso, também foi observado experimentalmente uma segunda componente mais rápida (~50 fs), que não pôde ser explicada dentro do modelo de difusão rotacional livre. Esta componente foi atribuída a efeitos reorientacionais coletivos em conjunto com efeitos de superposição temporal de pulsos. A interpretação do sinal desta nova técnica foi testada com sucesso realizando o experimento em tetracloreto de carbono.O terceiro sistema investigado foi a dinâmica de relaxação de energia intramolecular de carotenóides. A principal questão, da vii existência ou não de estados eletrônicos adicionais, foi abordada utilizando uma modificação da técnica de Bombeio e Prova, denominada de Bombeio-Depleção-Prova. A técnica de Bombeio-Depleção-Prova foi pela primeira vez utilizada em carotenóides, possibilitando observar dinâmicas nunca vistas por qualquer outra técnica experimental. Dentro da resolução temporal dos experimentos realizados, a presença de novos estados eletrônicos em carotenóides livres em solução é descartada. Além disso, uma nova ferramenta de análise de dados foi desenvolvida. A análise de alvos espectrais baseada em um algoritmo evolutivo trouxe mais argumentos para o modelo clássico de três níveis. A dinâmica de carotenóides livres em solução foi comparada com sua dinâmica quando inseridos no complexo fotossintético de coleta de luz (LH2) da bactéria púrpura, utilizando para isso a técnica de Bombeio e Prova. Os resultados obtidos mostram um sistema de níveis de energia mais complexo do que quando o carotenóide está livre em solução. Esta modificação devido ao ambiente é possivelmente gerada pela quebra de simetria do carotenóide quando inserido no complexo LH2, possibilitando o cruzamento entre sistemas (singlete-triplete).
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Schmidt, Ylva. "Statliga myndigheter publikationer på webben. En studie av femton myndigheters elektroniska publicering." Thesis, Uppsala University, Department of ALM, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-101634.
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Dag, Simon. "Femton svenskars skäl till att de slutat rösta på de politiska partierna." Thesis, Mälardalens högskola, Akademin för hälsa, vård och välfärd, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-49502.
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Mindre än hälften av svenska väljare uppger att de har stort förtroende för politiker. Kvantitativa data har legat till grund för tidigare forskning som sett samband mellan politikerförtroende och en mängd demografiska variabler. Kvalitativa studier inom ämnet saknas. Syftet med denna studie var att undersöka skäl till att deltagare som haft förtroende för politiker tappat förtroendet i den utsträckningen att de inte röstat alternativt röstat blankt i 2018 års riksdagsval. Totalt intervjuades 9 män och 6 kvinnor med varierande ålder (25-63) och utbildningsnivå. Materialet analyserades tematiskt och följande teman identifierades: Politiker har låg trovärdighet, Missnöjd med systemet, Saknar partiidentifikation och En oacceptabel nivå. Deltagare gav ofta specifika exempel på situationer som lett till tappat politikerförtroende. Förtroende har åtminstone delvis tappats då deltagare inte anser att politiker är ärliga och att politiker inte lever upp till deltagarnas förväntningar. Fortsatta studier inom området rekommenderas för att ge en helhetsbild över tappat politikerförtroende.
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Ek, Alice, and Linn Olsson. "Bilderboken - inkludering i litteraturform? : En normkritisk text- och bildanalys av femton bilderböcker." Thesis, Uppsala universitet, Institutionen för pedagogik, didaktik och utbildningsstudier, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-429303.
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Studiens syfte är att belysa om förskolor i tre områden runt om i Uppsala väljer att låna normkritiska bilderböcker utifrån sex av de sju diskrimineringsgrunderna. Ålder är undantagen och familj är istället tillagd relaterat till att det är bilderböcker vi analyserar. Vi kommer att beskriva dessa val närmre i uppsatsen. Utifrån tre tabeller tillhandahållna av bibliotekarie på Stadsbiblioteket för perioden 21/10, 22/10–2020 analyseras 15 bilderböckerna från 2000-talet utifrån ett normkritiskt perspektiv från tre olika bibliotek i Uppsala. Frågeställningarna är vilka diskrimineringsgrunder som synliggörs i bilderböckerna och hur dessa framställs utifrån ett normkritiskt perspektiv. I studien utgår vi från ett normkritiskt perspektiv grundat i queerteorin. Studiens resultat är att bilderböckerna som vi valt att analysera visar en minimal mångfald utifrån de olika diskrimineringsgrunderna. Genus är den diskrimineringsgrund som påvisats tillstörst del i bilderböckerna medan diskrimineringsgrunden hbtq inte synliggörs i någon av de analyserade bilderböckerna. Det vi fann mest intressant av resultatet i vår studie var att sju av de 15 utvalda bilderböckerna blev placerade under kategori X. Kategori X innebär att bilderböckerna inte utmanar eller uppmärksammar någon av de sex diskrimineringsgrunderna vi använder oss av i vårt analysschema. Vi ser även olika slags fokus på normkritik inom de tre olika områden vars utlåning studien granskar.
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Rakhimova, Elena. "Comparison of macro and femto cells considering power consumption." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-177910.
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Nowadays the traffic demand grows fast that requires careful chosen deployment strategy to increase capacity, but save investments. Another important subject is to save a power consumed mostly by base station itself and its backhaul network. So, what type of base stations must be chosen, what spectrum characteristics it has and what backhaul link is connected to it. All this aspects requires different approaches, as they have different capacity and cover characteristics. The motivation is to compare the solutions using different base station types and various backhaul solutions. The question if the spectral efficiency allows to increase the traffic throughput, it would decrease or increase power consumption and cost. The modern technologies propose several options, ones of them are macro cellar and femtocell network. The macro cell has a great ability to cover a big area, while the femtocell has a good capacity possibilities. Moreover, femtocell partially are paid and installed by end-users that decrease the installation and electricity cost for operators. However, operator can reuse existed sites which decrease investment cost of macrocellular network. So, the first milestone is to find the way how to fairly compare two different types of technologies. In this thesis the proposed scenario is composed in a very careful way to predict demand types, base stations possibilities and characteristics as well as the backhaul architecture. Then the more accurate model to deploy a femtocellular network has been described in detail. The more detailed cost strategy is introduced for backhaul solutions and described in detail. The power consumption calculations has been described in more clear way, to show the range of metrics, what value should it has: negative or positive. Some formulas is remade to reach more correct results. Another milestone is to bring all parameters to unique format that has been done to achieve right results. In the microwave backhaul solution, the topology case added and carefully described, because every topology case requires different formulas, in this thesis, the calculation steps for star and ring topologies presented. Steps how to calculate the base station radius depends on power characteristics of base station is provided. Since this thesis introduces improvements in several points, It is good guide to keep in track the received results and control the calculation process.
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Rutgersson, Sebastian. "Hit med framgång - En analys av femton framgångsrika hitlåtar mellan 1990 och 2006." Thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-95341.
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Syftet med detta arbete är att försöka definiera vad som gör en låt framgångsrik. Detta görs i tre steg genom hänvisning till existerande litteratur, intervjuer med branschmänniskor och med en analysmall baserad på litteraturen och intervjuerna. Med hjälp av mallen analyseras sedan femton låtar för att styrka eller förkasta de påståenden som görs i litteraturen och intervjuerna. I litteraturen nämns bland annat melodins och refrängernas betydelse för låtens framgång. Vidare diskuteras att harmoniken inte bör ta för stor plats, utan skall fungera som en transportsträcka för melodin. En till punkt som nämns är att refrängerna idag har större utrymme än vad de tidigare har haft. Många av ovanstående punkter nämns även i intervjuerna. Andra punkter som poängteras där är bland annat att låtarna behöver ha någonting eget för att nå framgång och att låtar med för djup text sällan plockas upp av musikläggare. I min undersökning har jag kunnat finna vissa gemensamma drag bland låtarna. De absolut viktigaste pekar på att det krävs en tydlig och stark melodi, tydliga refränger och att låten antingen erbjuder någonting eget, eller/och har kringliggande element som populariserar låten.
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Argilaga, Claramunt Albert. "FEMxDEM double scale approach with second gradient regularization applied to granular materials modelization." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI066/document.
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L'approche multi-échelle FEMxDEM est une méthode numérique innovante pour les problèmes géotechniques impliquant des matériaux granulaires. La méthode des éléments finis (FEM) et la méthode des éléments discrets (DEM) sont simultanément appliquées à résoudre, respectivement, le problème structurel à la macro-échelle et la microstructure du matériau à la micro-échelle. L'avantage d'utiliser une telle configuration à double échelle est de permettre d'étudier un problème d'ingénierie sans la nécessité de lois de comportement standard, capturant ainsi l'essence des propriétés des matériaux. Le lien entre les échelles est obtenu par homogénéisation numérique, de sorte que la loi de comportement continu numérique et la matrice tangente correspondante sont obtenues directement à partir de la réponse discrète de la microstructure.En règle générale, l'approche FEMxDEM présente quelques inconvénients; la vitesse de convergence et la robustesse de la méthode ne sont pas aussi efficaces que dans les modèles FEM classiques. De plus, le coût de calcul de l'intégration de la micro-échelle et la dépendance du maillage typique de la macro-échelle, rendent l'approche multi-échelle FEMxDEM discutable pour des utilisations pratiques. Le but de ce travail est de se concentrer sur ces questions théoriques et numériques avec l'objectif de rendre l'approche multi-échelle FEMxDEM robuste et applicable à des configurations à l'échelle réelle. Une variété d'opérateurs est proposée afin d'améliorer la convergence et la solidité de la méthode dans un cadre quasi-Newton. L'indépendance de l’intégration des différents points de Gauss et les caractéristiques d’intensivité sur les d'éléments sont exploités par l'utilisation d’une parallélisation en utilisant un paradigme OpenMP. Au niveau macro, une relation constitutive second gradient est mise en œuvre afin d'enrichir la relation de Cauchy de premier gradient apportant indépendance du maillage au modèle.Les améliorations susmentionnées rendent l'approche FEMxDEM compétitive avec les modèles FEM classiques en termes de coût de calcul permettant ainsi d'effectuer des simulations multi-échelle FEMxDEM robustes et indépendantes du maillage, depuis l'échelle du laboratoire (par exemple essaie biaxiale test) jusqu’à celle du problème à l'échelle de l'ingénierie (par exemple, excavation d’une galerie).Mots clés:Double échelle, homogénéisation numérique, loi constitutive numérique, élasto-plasticité, second gradient, matériaux microstructurés, grande déformation, éléments finis, éléments discrets, méthode de Newton, parallélisation, unicitéThe multi-scale FEMxDEM approach is an innovative numerical method for geotechnical problems involving granular materials. The Finite Element Method (FEM) and the Discrete Element Method (DEM) are simultaneously applied to solve, respectively, the structural problem at the macro-scale and the material microstructure at the micro-scale. The advantage of using such a double scale configuration is that it allows to study an engineering problem without the need of standard constitutive laws, thus capturing the essence of the material properties. The link between scales is obtained via numerical homogenization, so that, the continuum numerical constitutive law and the corresponding tangent matrix are obtained directly from the discrete response of the microstructure.Typically, the FEMxDEM approach presents some drawbacks; the convergence velocity and robustness of the method are not as efficient as in classical FEM models. Furthermore, the computational cost of the microscale integration and the typical mesh-dependency at the macro-scale, make the multi-scale FEMxDEM approach questionable for practical uses. The aim of this work is to focus on these theoretical and numerical issues with the objective of making the multiscale FEMxDEM approach robust and applicable to real-scale configurations. A variety of operators is proposed in order to improve the convergence and robustness of the method in a quasi-Newton framework. The independence of the Gauss point integrations and the element intensive characteristics of the code are exploited by the use of parallelization using an OpenMP paradigm. At the macro level, a second gradient constitutive relation is implemented in order to enrich the first gradient Cauchy relation bringing mesh-independency to the model.The aforementioned improvements makes the FEMxDEM approach competitive with classical FEM models in terms of computational cost thus allowing to perform robust and mesh-independent multi-scale FEMxDEM simulations, from the laboratory scale (e.g. biaxial test) to the engineering-scale problem, (e.g. gallery excavation).Keywords:Double scale, numerical homogenization, numerical constitutive law, elasto-plasticity, second gradient, microstructured materials, large strain, finite elements, discrete elements, Newton method, parallelization, uniqueness
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Afridi, Ayaz Khan. "MACRO AND FEMTO NETWORK ASPECTS FOR REALISTIC LTE USAGE SCENARIOS." Thesis, KTH, Kommunikationsnät, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-53752.
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Bharucha, Zubin Rustam. "Ad hoc wireless networks with femto-cell deployment : a study." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4720.
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Nowadays, with a worldwide market penetration of over 50% in the mobile telecommunications sector, there is also an unrelenting demand from the subscribers for ever increasing transmission rates and availability of broadband-like experience on the handset. Due to this, research in next-generation networks is rife. Such systems are expected to achieve peak data rates of up to 1 Gbps through the use of innovative technologies such as multiple-input and multipleoutput (MIMO) and orthogonal frequency division multiple access (OFDMA). Two more ways of boosting capacity have also been identified: shrinking cell sizes and greater reuse of resources in the same area. This forms the foundation of the research presented in this thesis. For operators, the costs involved with planning and deploying additional network infrastructure to provide a dense coverage of small, high capacity cells cannot be justified. Femto-cells, however, promise to fulfil this function. These are user-deployed mini base stations (BSs), known as home evolved NodeBs (HeNBs), which are envisaged to be commonplace in homes and offices in the coming years. Since they drastically reduce communication distances to user equipments (UEs) and reuse the resources already utilised in the macro-cell, they help boost the system capacity significantly. However, there are issues to be addressed with the deployment of femto-cells, such as increased interference to the system and methods of access. These and other problems are discussed and analysed in this thesis. One of the first steps towards femtocell research has been the study of the time division duplex (TDD) underlay concept, whereby an indoor UE acts as a relay between the evolved NodeB (eNB) and other indoor UEs. In order to gain a deeper understanding of how and under what conditions such a self-organising network can be deployed, a mathematical analysis of the distribution of path losses in a network of uniformly distributed nodes has been performed. In connection with this, research has also been done in the identification of well connected nodes in such networks. Next, extensive simulations on traditional cellular networks with embedded femto-cells have been carried out in order to demonstrate the benefits of femto-cell deployment. This research has shown that femto-cells can cause severe downlink (DL) interference to badly placed macro UEs. Finally, a novel interference avoiding technique that addresses this problem is investigated.
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Hugelius, Anna. "Manliga socionomstuderandes syn på kunskap och lärande : En kvalitativ studie av femton socionomstuderande män." Thesis, Örebro universitet, Institutionen för juridik, psykologi och socialt arbete, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-28558.
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Witting, Tobias. "New techniques for the characterisation of femto- and attosecond light pulses." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.542994.
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Ahmad, Muhammad Bilal. "Macro and Femto Network Aspectsfor Realistic LTE usage scenarios with Interference Management." Thesis, KTH, Kommunikationsnät, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-116601.
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Agyekum, Isaac. "Electrochemical Studies of Reactions in Small Volumes Less Than 1 Femto Litres." Digital Commons @ East Tennessee State University, 2011. https://dc.etsu.edu/etd/1316.
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Electrochemical methods have been used to study electron transfer reactions at the interface between an aqueous phase of less than 1 femto liters in volume and a bulk organic phase. The small aqueous phase is formed at the end of a slightly recessed platinum electrode. When a negative potential is applied between the Pt electrode and the aqueous phase, Ru(NH3)63+ in the aqueous phase could be reduced to Ru(NH3)62+. Because the volume of the aqueous phase is very small, the electrochemically formed Ru(NH3)62+ could instantly reach the interface between the aqueous phase and the organic phase which contains 7,7,8,8-Teteracyanoquinodimethane (TCNQ), and be oxidized to form Ru(NH3)63+ by giving electrons to TCNQ at the interface. Our results showed a positive shift in the E1/2 comparing the reaction undertaken in the recessed cavity and the bulk solution.
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Griffiths, Ian Michael. "Location techniques for pico- and femto-satellites, with applications for space weather monitoring." Thesis, University of Leicester, 2017. http://hdl.handle.net/2381/39973.
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Space weather phenomena have a significant impact on satellite communications but are not well understood. In-situ measurements of the ionospheric environment would significantly improve the understanding of the origins and progressions of these phenomena. Whilst previous scientific satellites have measured the ionospheric plasma, they only provide a limited view due to their small number. It has previously been suggested that a swarm of femto-satellites (PCBsats) could be used to collect high quality temporal and spatial measurements, whilst being financially effective. To give the measurements any scientific value, the location and time of each measurement needs to be accurately recorded. The PCBsat prototype used a solution that, due to export requirements and fundamental limitations with the device, would not be capable of working in space. Several location and timing solutions have been investigated, with none matching the precision, accuracy, power consumption and physical size of a GNSS receiver (i.e. a receiver of GPS, GLONASS, Galileo etc. signals). To further reduce the power consumption, a novel distributed GNSS receiver has been designed and built, where the largest computational burden (calculating the receivers position) is offloaded to a relaying node. This use of distributed computing has been shown to reduce the power consumption of the receiver by between 5:6% and 13:3% - which is equivalent to between 2 and 5 times the power consumption of the PCBsat’s main processor. In addition to this, this novel approach has the additional benefit of being used in a hybrid scheme. Where information required to calculate a receiver’s position is stored so that it can be used with higher precision ephemerides that are publicly available but are delayed by up to three weeks. This has many applications as it can increase the utility of collected data, at a reduced cost. As the intended femto-satellite application relies on a link to relaying satellites, the dynamics, in particular the dispersion, of the intended constellation needs to be known. This has been modelled using a novel orbit simulator. The orbit simulator is the first of its kind to model multidimensional free molecular drag to simulate the effects of the low density atmosphere on a satellite. This allows the dispersion of a constellation of satellites to be investigated with maximum separations for the PCBsat being presented.
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Bermingham, Charlotte R. "Measurement of pico/femto-Newton scale forces using the lateral molecular force microscope." Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.715803.
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Välitalo, Emelie. "`Det är en jätte attitydförändring på femton år´ : - Normalisering av cannabis bland studenter och utmaningar för studenthälsan." Thesis, Luleå tekniska universitet, Samhällsvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-64662.
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Larsson, Erik. "Ett universum av tecken : En analys av intertextuella relationer i femton svenska recensioner av Michel Houellebecqs "Underkastelse"." Thesis, Linnéuniversitetet, Institutionen för film och litteratur (IFL), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-49675.
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Abrahamsson, Anna, and Jenny Häkänen-Muhanga. ""Det kan sitta femton ungar och bara äta blåbär" : En undersökning om hur förskollärare arbetar med utomhuspedagogik." Thesis, Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-30817.
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Syftet med undersökningen är att dels ta reda på hur förskollärare tänker kring utomhusvistelsens syfte. Syftet är även att utifrån de ramfaktorer som finns i verksamheten, undersöka hur förskollärare arbetar med utomhuspedagogik. En kvalitativ ansats med semistrukturerade intervjuer har genomförts med åtta informanter. Resultatet visar att förskollärare har olika syften med barns utomhusvistelse, samt att olika ramfaktorer kan påverka förskollärares arbete med utomhuspedagogiken. Slutsatsen är att ett pedagogiskt respektive romantiskt synsätt genomsyrar förskollärares arbete med utomhuspedagogik, samt att det råder en viss omedvetenhet kring olika ramfaktorer och dess påverkan på arbetet med utomhuspedagogik.
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Cui, Zhen. "Mechanistic studies of neutral and synthetic metallo-sulfur clusters." Thesis, University of East Anglia, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251443.
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Krichen, Mariem. "Modèle technico-économique pour le déploiement d'un réseau femto avec le partage de ressources." Versailles-St Quentin en Yvelines, 2014. http://www.theses.fr/2014VERS0011.
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Aujourd’hui, les opérateurs mobiles veulent offrir une qualité de service correcte à leurs clients alors qu’ils se trouvent au cœur d’un scénario catastrophique avec des demandes de données doublant d’une année à une autre, des réseaux atteignant leur limite de capacité et des revenus stables dus aux tarifs forfaitaires. Nous proposons dans cette thèse d’exploiter des accès femto installés chez les clients. Cette solution implique la gestion de différents types de cellules. Les mécanismes d’auto-configuration des cellules seraient donc vitaux aux opérateurs mobiles. La première partie de la thèse compare les performances de trois algorithmes pour l’auto-configuration des identifiants physiques de cellules en LTE. Dans la deuxième partie, nous présentons un modèle technico-économique où deux types d’acteurs interagissent. Tout d’abord, les fournisseurs d’accès femto sont les clients de l’opérateur mobile qui ont un accès femto chez eux et qui acceptent de partager une partie de leur bande passante. Puis, les consommateurs d’accès femto sont les clients qui ont besoin d’une bonne qualité de service à l’extérieur. Dans le problème de partage d’accès femto, les consommateurs sont en compétition pour accéder aux ressources des fournisseurs. Cette compétition est modélisée sous forme d’un jeu où les consommateurs comptent sur un mécanisme d’apprentissage pour adresser leur requête. Nous évaluons les performances de ce mécanisme pour différentes charges du réseau et quelques scénarios où la compétition entre les consommateurs diffère. Enfin, ce mécanisme est implémenté dans un contexte statique et un contexte dynamique. Nous proposons une solution aux problèmes de mobilitéNowadays, the mobile operators want to offer a correct quality of service to their clients while they are in the heart of a catastrophic scenario with data request doubling from one year to another, networks reaching their capacity limits and stable revenues due to flat rate. The solution that we propose in this thesis is the exploitation of femto accesses, set up at clients place, through sharing resources. Since many types of cells should be managed with the introduction of femto cells, self-configuration mechanisms would be vital for mobile operators. The first part of this thesis compares the performances of three algorithms for the self-confi guration of the physical cell identifier in LTE. In the second part of the thesis, we present a techno-economic model where two types of actors interact. First, the femto access providers are the mobile operator clients who own femto access at their place and accept to share part of their bandwidth with other clients. Then, the femto access requesters are the mobile operator clients who need a good quality of service outdoor. In sharing femto access problem, requesters are competing to access providers resources. This competition is modeled as a game where requesters rely on a learning mechanism to address their requests. Through simulations, we evaluate the performances of this mechanism for different network loads and scenarios where competition between requesters differs. Finally, this mechanism is implemented on a static context then on a dynamic one. We propose a solution to mobility issues based on cells categorization
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Golebiowski, Dariusz. "High resolution FTIR spectroscopy using a femto-OPO laser source and cavity enhanced absorption." Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/221150.
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Dans cette thèse, nous améliorons et utilisons le montage expérimental développé au laboratoire nommé femto/OPO-FT-CEAS. Ce montage combine une source laser femto/OPO, une cavité optique haute finesse et un interféromètre à transformée de Fourier. Il permet d'enregistrer des spectres sur un intervalle de 150 cm-1, avec un coefficient d'absorption minimal de 3x10-9 cm-1, à une résolution de 2x10-2 cm-1 et un temps d’acquisition de 2 heures. Un chemin d'absorption de 20 km a été obtenu dans une cellule de 145 cm. Différents miroirs à hauts indices de réflexion permettent d'accéder à deux gamme spectrales dans le domaine de l'infrarouge proche :6200-6700 cm-1 et 7700-8300 cm-1.Le montage femto/OPO-FT-CEAS a été utilisé afin d'enregistrer des spectres à température ambiante. La molécule OCS a été étudiée dans les gammes spectrales de 6200 à 6700 cm-1 et 7700 à 8300 cm-1. Les nouvelles données rovibrationnelles ont été intégrées au modèle global développé par le Prof. Fayt de l'université catholique de Louvain. Un échantillon de CO2 enrichi en oxygène 17 a également été étudié dans la gamme spectrale de 7700 à 8300 cm-1. Les données ont été traitées avec l'aide du Dr. Lyulin l'institut d'optique atmosphérique de Tomsk, Russie.Le montage femto/OPO-FT-CEAS a également été modifié pour enregistrer des spectres de molécules refroidies au sein d'un jet supersonique. Les molécules de N2O, C2H4 et H12C13CH en abondance isotopique naturelle ont été étudiées. Le montage permet de refroidir les molécules étudiées jusqu'à 10 K et un coefficient de 5x10-8 cm-1 a été obtenu. Ce montage a également permis d'enregistrer des spectres CEAS et CRDS de NH3 à des températures de 17 et 14 K respectivement. L'analyse des spectres aété réalisée avec l'aide des Profs. Fusina et Di Lonardo de l'Université de Bologne, Italie.Une cellule de 145 cm pouvant être refroidie à l'aide de réfrigérants liquides a également été développée en vue de remplacer une cellule à température ambiante de 77 cm utilisée dans le montage femto/OPO-FT-CEAS.Enfin, les montages FANTASIO+ et femto/OPO-FT-CEAS ont été utilisés afin afin d'enregistrer des spectres de HCOOH à température ambiante et à 10 K. Les données ont été traitées avec l'aide du Dr. Perrin de l'Université Paris-Créteil, France.Doctorat en Sciences
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De, Domenico Antonio. "Technique de gestion de ressources radios pour l'amélioration de l'efficacité énergétique dans les réseaux cellulaires hétérogènes." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENM012/document.
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Les communications sans fil prolifèrent dans presque chaque aspect de la société humaine : puissants ‘smart-phones' et ‘tablets', accès haut débit sans fil, et communications ‘machine-to-machine' ont généré des volumes de trafic de données imprévisibles quelques années en arrière. Dans ce nouveau paradigme, l'industrie des télécommunications se doit de garantir à la fois la durabilité économique des communications sans fil à large bande ainsi que la qualité de son service. En outre, il y a une forte incitation sociale à réduire les émissions de C02 duent aux communications mobiles, qui a augmenté notamment dans la dernière décennie. Dans ce contexte, l'intégration des ‘femtocells' dans les réseaux cellulaires est une solution à faible coût pour offrir une qualité de service élevée et en même temps de décharger le réseau macrocellule. Cependant, le déploiement massif et chaotique des points d'accès femtocell et leurs opérations non coordonnées peuvent conduire à une augmentation de l'interférence co-canal. De plus, un nombre élevé de cellules faiblement chargées augmente la consommation énergétique du réseau. Dans cette thèse, nous avons étudié les effets du déploiement de femtocells sur l'efficacité énergétique du réseau cellulaire. Par ailleurs, nous investiguons sur les mécanismes d'adaptation pour les réseaux des femtocells comme un moyen pour améliorer l'efficacité des communications mobiles. Notre objectif est de répondre dynamiquement à la demande des ressources afin de limiter la consommation d'énergie moyenne et l'interférence co-canal, tout en garantissant la qualité de service. Nous profitons du contexte inhabituel de communication ‘femtocellulaire' pour proposer des mécanismes d'allocation des ressources et des systèmes de gestion de réseau qui coordonne l'activité des points d'accès, la consommation d'énergie et de la couverture. Les résultats des simulations montrent que nos propositions améliorent l'efficacité énergétique et les performances perçues par les utilisateurs du système dans les réseaux ‘femtocellulaires' coopératives et autonomesWireless communication proliferates into nearly each aspect of the human society, driving to the exponential growth in number of permanently connected devices. Powerful smart-phones and tablets, ubiquitous wireless broadband access, and machine-to-machine communications gen- erate volumes of data traffic that were unpredictable few years back. In this novel paradigm, the telecommunication industry has to simultaneously guarantee the economical sustainability of broadband wireless communications and users' quality of experience. Additionally, there is a strong social incentive to reduce the carbon footprint due to mobile communications, which has notably increased in the last decade. In this context, the integration of femtocells in cellular networks is a low-power, low-cost solution to offer high data rates to indoor customers and simultaneously offload the macrocell network. However, the massive and unplanned deployment of femtocell access points and their uncoordinated operations may result in harmful co-channel interference. Moreover, a high number of lightly loaded cells increases the network energy consumption. In this thesis, we investigate the effects of femtocells deployment on the cellular network energy efficiency. Moreover, we look into adaptive mechanisms for femtocell networks as a means to pave the way towards agile and economically viable mobile communications. Our goal is to dynamically match resource demand and offered capacity in order to limit the average power consumption and co-channel interference while guaranteeing quality of service constraints. We take advantage of the unusual communication context of femtocells to propose resource allocation and network management schemes that coordinate the access points activity, power consumption, and coverage. Simulation results show that our proposals improve system energy efficiency and users' performance in both networked and stand-alone femtocell deployment scenarios
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de, Ghellinck d'Elseghem Vaernewijck Xavier. "Instrumental contribution to FTIR spectroscopy using a femto-OPO laser source and cavity enhanced absorption." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209629.
Full textAbstract:
L'expérience nommée femto-FT-CEAS a été mise en place durant ce travail. Ellecombine une source d'absorption laser femto-opo, une cavité optique haute finesse
et un interféromètre à transformée de Fourier. Ce montage instrumental a permis
d'enregistrer des spectres sur un domaine de 100 cm−1 avec un coefficient d'absorption
minimal détectable de 5 10−10cm−1 pour des paramètres de résolution spectrale de
2 10−2cm−1 et un temps d'enregistrement d'une heure. Le coefficient d'absorption
equivalent par moyenne quadratique par élément spectral correspondant est de 1.2
10−12cm−1 Hz−1/2. Un chemin optique équivalent de 13 km a été obtenu dans une
cellule de 77 cm de long. La gamme spectrale accessible est de 6000 − 6700 cm−1 et
7800 − 8300 cm−1.
Les spectres enregistrés à l'aide du montage femto-FT-CEAS ont permis d'attribuer
plus de 1000 transitions rovibrationelles d'échantillons de CO2 enrichis en 17O,
d'OCS, CS2, H12C13CD, et CH3CCH. Les bandes suivantes ont été enrégistrées :
pour 12C17O2, les bandes 30013e, 30012e, 30011e, 31113e, 31113f, 31112e, 31112f,
et 31111e; pour 17O12C18O, les bandes 30013e, 30012e, et 30011e; pour 16O12C32S,
les bandes 540, 0, 501, 0, 511, 1e, 511, 1f, 601, 0, 460, 0, 421, 0, 431, 1e, 431, 1f,
521, 0, 341, 0, 351, 1e, 351, 1f, 302, 0, 312, 1e, 312, 1f, 402, 0, 322, 2e, et 322, 2f;
pour 16O12C34S, les bandes 501, 0 et 302, 0; pour 16O13C32S, la bande 302, 0 ;pour
16O12C33S, la bande 302, 0; pour 12C32S2, les bandes 0403, 0114, 3003 et 2203; pour
32S12C34S, la bande 3003. Les conventions de notation vibrationelles utilisées ici sont
pour CO2, ν1 ν2 l ν3 n où les bandes vibrationelles perturbées par la résonance de
Fermi ν1 2ν2 sont ordonnées selon n par ordre décroissant d'énergie. Pour l'OCS,
les conventions de notation sont ν1 ν2 ν3, l et pour le CS2, ν1 νl2 ν3. Leur analyse
spectrale a été réalisée, aboutissant à de nouvelles constantes rovibrationelles ou des
constantes améliorées par rapport à celles de la littérature. Les raies rovibrationnelles
attribuées sont données. L'analyse des spectres de H12C13CD et de CH3CCH a étéréalisée par l'équipe du Pr. L. Fusina (Université de Bologne, Italie).
L'expérience a aussi été installée autour d'un jet supersonique, enregistrant les
structures rotationnelles des bandes vibrationelles ν5 + ν9 de C2H4, 3ν3 de N2O et
ν1 + ν3 de H12C13CH en abondance naturelle, toutes avec une température rotationelle
inférieure à 35 K.
Finalement, un programme de simulation de ligne de base a été écrit.
Doctorat en Sciences de l'ingénieur
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Sahlin, Matilda. "Så du menar att du har tagit tior, istället för femmor? : - En studie om laborativ matematikundervisning ur ett lärarperspektiv." Thesis, Högskolan i Gävle, Avdelningen för elektroteknik, matematik och naturvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-29693.
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I dagens skola har det givits större plats till den laborativa matematikundervisningen för att minska den teoretiska tysta räkningen. Det här kommer studien att fördjupa sig igenom frågeställningarna: · Vilka laborativa material använder lärare i grundskolans yngre åldrar i matematikundervisningen inom addition och subtraktion i Gävleområdet? · Vilka upplevelser har lärare i Gävleområdet av det laborativa arbetssättet i matematikundervisningen? Och vad deras upplevelser beror på? · På vilket sätt kan en lektion med ett laborativt material inom området addition och subtraktion, skapa a-didaktiska-situationer? Två metoder kommer att användas för att samla in data för studien: två enkäter och en observation genom ett teoretiskt ramverk. Enkäterna visar vilka laborativa material som lärare använder i Gävleområdet, samt deras upplevelser kring materialet. Observationen är en fallstudie där eleverna får arbeta med laborativt material och resultatet visar att det laborativa materialet ökar elevernas kommunikation kring innehållet. Resultatet från undersökningarna stärks även av tidigare forskning som tyder på att laborativ undervisning har en positiv effekt på elevers kunskapsutveckling.
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Paul, Pierre-Marie. "Ionisation multiphotonique xuv-ir : etudes et applications a la mesure d'impulsions xuv femto et atto secondes." Paris 6, 2001. http://www.theses.fr/2001PA066349.
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Ce travail de these a pour cadre general l'etude des transitions multiphotoniques impliquant un photon xuv et un ou plusieurs photons infrarouges. En effet, lorsqu'un rayonnement xuv monochromatique photoionise un atome en presence d'un rayonnement electromagnetique infrarouge intense, plusieurs photons infrarouges peuvent etre absorbes, au-dessus du seuil d'ionisation, en exces du photon xuv. Le but de ce travail de these est l'etude des proprietes de certains de ces processus dits a plusieurs couleurs dans la limite perturbative et au-dela. La mise en uvre de ce type d'experiences est grandement facilitee lorsqu'on utilise comme source xuv les harmoniques d'ordres eleves generes dans les gaz rares. Les recherches relatees dans ce travail de these presentent un aspect fondamental et un aspect applique. Du point de vue fondamental, nous avons mis en evidence des effets comme, l'interference entre les differents chemins quantiques d'une transition a deux photons/trois couleurs, le dichroisme circulaire et la modification des distributions angulaires de photoelectrons en presence du champ infrarouge intense. Nous avons egalement initie les premieres recherches concernant la double photoionisation a deux photons et deux couleurs. Cette derniere experience d'une grande difficulte est susceptible de fournir les premiers resultats prochainement. Du point de vue des applications, nous avons developpe deux methodes originales permettant la mesure d'une impulsion xuv avec une resolution de 3fs et celle du battement attoseconde d'un groupe d'harmoniques d'ordres consecutifs. Cette derniere methode permet la reconstruction d'un train d'impulsions attosecondes par mesure des phases relatives d'un groupe d'harmoniques d'ordres consecutifs. Nous avons pu ainsi mesurer, pour la premiere fois, des impulsions de 250 as de duree.
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Johansson, Caroline, and Linda Karlsson. "Grovmotorik - ett bortglömt inslag i dagens förskola? : En undersökning om grovmotorikens betydelse i dag jämfört med för femton år sedan." Thesis, Linnéuniversitetet, Institutionen för utbildningsvetenskap (UV), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-29249.
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Syftet med vår undersökning är att belysa hur förskollärare tänker kring barns grovmotoriska utveckling i dag jämfört med för femton år sedan. Vi vill även skapa en förståelse för varför och hur en eventuell förändring har skett. Detta gör vi genom att fråga hur pedagogens förhållningssätt till barns grovmotoriska utveckling ser ut idag jämfört med för femton år sedan. Undersökningen följer kvalitativa forskningsmetoder med intervjuer under fysiska möten. Resultatet visar att grovmotorisk träning har ett mindre utrymme i förskolan i dag jämfört med för femton år sedan och det är främst tre faktorer som påverkar hur mycket det blir – tid, gruppstorlek och medvetenhet. Forskningen visar att en välutvecklad grovmotorik är betydelsefull för inlärningen. Enligt informanterna tillskrivs förskolan fler målformuleringar vilket innebär att fler uppdrag ska rymmas inom samma tid som förut och motoriken får ge vika. Fler barn skrivs in i grupperna vilket påverkar förutsättningarna för grovmotorisk träning i förskolan då lokaler och personaltäthet förblir detsamma. Pedagogernas medvetenhet påverkar mängden grovmotorisk träning i förskolans verksamhet. Det visar sig i den enskilda pedagogens intresse för motorik och rörelse och även dess syn på motorikens betydelse i leken. För att kunna delta och leka med en god självkänsla behövs en motoriskt säker kropp samt en god kroppsuppfattning. Till skillnad mot för femton år sedan, integrerar idag den medvetne pedagogen den grovmotoriska träningen i leken.
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Van, Tassel John Peter. "Femto-VHDL : the semantics of a subset of VHDL and its embedding in the HOL proof assistant." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308190.
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Chang, Soon-Ho. "Intercalation, désintercalation de métaux alcalins dans quelques nouvelles structures hôtes : LiNbO₂, NaNbO₂, FeMoO₄Cl et LiW₃O9F." Bordeaux 1, 1989. http://www.theses.fr/1989BOR10559.
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Erlandsson, Johanna, and Charlotte Gårlin. "Om man bara öppnar en dörr, finner man femton miljoner andra dörrar : En studie om hur chefer vid IKEA Jönköping uppfattar arbetsgivarvarumärket." Thesis, Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Livslångt lärande/Encell, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-20222.
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I denna studie undersöks chefers uppfattning om vad som attraherar, behåller och utvecklar dem med deras arbete. Syftet är att analysera deras uppfattning av IKEA som arbetsgivarvarumärke samt se hur uppfattningen förändras under deras anställningstid. Bakgrunden till studien baseras på samspelet mellan individ och organisation samt forskning om begreppet arbetsgivarvarumärke. Studien genomförs med en kvalitativ metod och en konstruktionistisk ontologisk utgångspunkt. Empiri samlades in genom sex semistrukturerade intervjuer med chefer på IKEA Jönköping. Vilken sedan analyserades med inspiration av en fenomenografisk utgångspunkt för att finna variationer av uppfattningar. I resultatet urskiljs skillnader i hur cheferna uppfattar arbetsgivarvarumärket i de tre faserna attrahera, behålla och utveckla. Cheferna attraherades av försörjning, anställningstrygghet och personlig utveckling. Deras uppfattning om arbetsgivarvarumärket är i dag mer samstämmig där fokus ligger på organisationskultur och utveckling. Inför framtiden uppfattar respondenterna möjligheten till utveckling som en viktig del av arbetsgivarvarumärket. Genom att samla arbetet kring attrahera, behålla och utveckla personal stärks arbetsgivarvarumärket. Detta är något som kan förtydliga Human Resource avdelningens roll i organisationen.
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Ståhlberg, Camilla. "Ett lyckat miljömålsarbete: En studie av vad tjänstemän på regional och lokal nivå tycker är viktigt i arbetet med de femton miljökvalitetsmålen." Thesis, Linköping University, Department of Thematic Studies, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2454.
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Studien ger en bild av hur tjänstemän på regional och lokal nivå ser på miljömålsarbetet. Syftet med studien har varit att skapa en förståelse för hur tjänstemän, som aktivt arbetar med miljömålen på en länsstyrelse och en kommun, uppfattar miljömålsarbetet och vilka faktorer som de anser är viktiga för ett lyckat miljömålsarbete. Studien baseras på kvalitativa intervjuer med sju tjänstemän från en länsstyrelse och en kommun. Fokus har legat på de intervjuade tjänstemännens syn på åtgärdsarbetet på den egna myndigheten.
De problem som verkar vara mest centrala för intervjupersonerna i miljömålsarbetet är resursbrist, att det saknas politisk förankring, att inte tillräckligt många olika aktörer är delaktiga i arbetet, att det är ett brett område och att det är svårt att integrera miljömålen i myndigheternas ordinarie verksamhet. Fördelarna verkar främst vara att många vill delta i arbetet, att man har gemensamma mål som är beslutade av riksdagen, att man har en enhetlig struktur som går från nationell till regional och lokal nivå och att det finns ett system för uppföljning.
De faktorer som i studien framstår som mest centrala för ett lyckat miljömålsarbete är brett deltagande, samverkan, nätverk, integration av miljömålen i andra samhällsmål och i befintlig verksamhet inom myndigheterna, politisk förankring samt informationsspridning genom dialog och marknadsföring. Även att skapa bättre förutsättningar för människor att ändra sitt beteende i en miljövänligare riktning anses vara viktigt. Det handlar då främst om resursfrågor och att åstadkomma en tydligare styrning från nationell nivå, men även juridiska styrmedel och ett effektivt uppföljningssystem.
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Wenninger, Matthias. "Sensitizing mechanisms, reaction mechanisms and reactive intermediate states in photocatalytic reactions on time scales from femto- to microseconds." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-176226.
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The development of renewable energy sources depicts a constantly growing interdisciplinary research field. Beyond photovoltaics chemical photocatalysis plays a small role, but is gaining more and more importance. In photocatalysis, light serves as an energy source for the chemical conversion of certain molecules. However, not only the application of photocatalysis as energy source but also the utilization of photocatalysis in chemical synthesis has attracted a deep scien- tific interest. For the optimization of photocatalytic systems a fundamental understanding oft the underlying processes is more than essential. Thereby, transient absorption spectroscopy has proved to be a very useful tool. On the one hand, the operation of a setup for transient absorption spectroscopy and on the other hand the systematic data evaluation requires physical and mathe- matical skills whereas the results cannot be interpreted without deep chemical knowledge. With- in the framework of the present thesis the cooperation between the fields of organic chemistry and physics has turned out as a very productive cooperation. Sensitizing mechanisms, reaction mechanisms and reactive intermediate states in photocatalytic reactions on time scales from femto- to microseconds are the object of the present work.
The present thesis will prove that the analysis of measurement data on the basis of established standard methods, such as the fitting of a sum of exponential functions to the temporal evolution of the measured signal, often is not sufficient for a complete interpretation of the data. Only a data analysis precisely adapted to the problem can lead to a fundamental understanding of the underlying processes.
In the first part of the present thesis, the focus lies on light-induced intramolecular charge transfer processes. Marcus Theory, which depicts the theoretical background, will be briefly in- troduced. On the basis of a molecular donor-bridge-acceptor system it will be shown that the damping coefficient β is not sufficient to differ unambiguously between coherent tunneling and incoherent hopping mechanism.
Flavin-capped DNA hairpins serve as a model for the investigation of intramolecular charge transfer processes. After photo-excitation, flavin induces a hole which migrates through the DNA strand. It will be shown that an adapted base sequence allows for quantum yields of ΦCS = 14% for long-lived charge separated states.
In the next section it will be discussed if the building blocks of the DNA are adapted to serve as chiral backbone for enantioselective photocatalysis. The conformation-dependent charge- transfer dynamics in benzophenone-DNA dinucleotides will be put on solid ground with the help of Marcus Theory. It will be shown that these dinucleotides are generally not suited to serve as an inert backbone for every kind of photochemical reaction.
In the following section a true bimolecular photocatalytic reaction will be discussed. Flavin serves as photocatalyst for the conversion of an alcohol to the corresponding aldehyde. A pre- cisely adapted data analysis allows and exact quantification of the diffusion controlled reaction dynamics on the ps time scale. The understanding of the process allows optimizing the reaction conditions. The targeted utilization of triplet chemistry within this reaction can help to increase the quantum yield for product formation.
As photo-induced charge transfer processes have been intensively discussed, the focus in the second part of the thesis lies on the [2+2] photocycloaddition. As basis for the interpretation of subsequent measurements, the [2+2] photocycloaddition of substituted quinolones will be inves- tigated. The formation of the cyclobutane ring in which the quinolone triplet state plays the cen- tral role will be characterized and quantified on the time scale from ps to ns. Afterwards the [2+2] photocycloaddition of substituted quinolones will be initiated by a chiral xanthone-based photocatalyst. It will be shown that within this catalyst-substrate complex in which both constit- uents have a distance of only few Ångströms, new electronic properties appear. The photo- excitation of a new electronic state not only initiates the [2+2] photocycloaddition of the quino- lone but also depicts a new sensitizing mechanism, which has to the author’s best knowledge not been observed in photocatalysis of organic molecules. The quinolone triplet state does not appear in this mechanism. The question, if this mechanism can be transferred to other photocatalytic systems has to be answered within the framework of further studies.Die Erforschung nachhaltiger und ressourcenschonender Energiequellen bildet ein stetig wachsendes, interdisziplinäres Forschungsfeld. Neben der Photovoltaik, die inzwischen eine etablierte Energiequelle darstellt, ist die chemische Photokatalyse noch ein kleines, aber stets wachsendes Teilgebiet. In der Photokatalyse dient das einfallende Licht dazu, chemische Ver- bindungen umzuformen. Nicht nur die Anwendung der Photokatalyse für die Energiegewinnung, sondern auch der Einsatz in der chemischen Synthese stößt dabei auf wachsendes Interesse. Um photokatalytische Systeme zu optimieren ist ein fundamentales Verständnis der Prozesse erfor- derlich. Die transiente Absorptionsspektroskopie hat sich dabei als geeignetes Werkzeug erwie- sen. Der Betrieb eines Aufbaus zur Messung transienter Spektren auf verschiedenen Zeitskalen und die gezielte Datenauswertung erfordert fundiertes physikalisches und mathematisches Ver- ständnis, wohingegen die Interpretation der Ergebnisse nicht ohne chemisches Wissen erfolgen kann. Im Rahmen dieser Arbeit hat sich die Kooperation zwischen der organischen Chemie und der Physik als erfolgreiche Zusammenarbeit erwiesen. Gegenstand der vorliegenden Arbeit sind die Sensibilisierungsmechanismen, die Reaktionsmechanismen und die reaktiven Intermediate in photokatalytischer Reaktionen auf Zeitskalen von Femto- bis Mikrosekunden. Es wird gezeigt, dass die Auswertung von Datensätzen mit Standardmethoden, wie der Anpas- sung einer Summe von Exponentialfunktionen an die zeitliche Entwicklung des Signals oft nicht ausreichend ist, um die Messdaten hinreichend zu interpretieren. Erst eine der Problemstellung exakt angepasste Datenanalyse führt zum Verständnis der zugrundeliegenden Prozesse. Zunächst werden lichtinduzierte intramolekulare Ladungstransferprozesse behandelt. Die the- oretische Basis für die Beschreibung solcher Prozesse bildet die Marcus-Theorie, die kurz einge- führt wird. Anhand eines molekularen Donor-Bridge-Acceptor-Systems wird gezeigt, dass der exponentielle Dämpfungskoeffizient β oft ungeeignet ist um der Reaktion einen kohärenten Tun- nelprozess oder einen inkohärenten Transfermechanismus zuzuweisen. DNS-Haarnadelstrukturen, welche kovalent mit einem Flavin-Chromophor verbunden sind, dienen als Modellsystem für die Untersuchung intramolekularer Ladungstransferprozesse. Nach Anregung induziert Flavin eine Elektronenfehlstelle in dem benachbarten DNS-Strang, die den Strang entlangwandern kann. Es wird gezeigt, dass durch die geeignete Wahl der Basensequenz eine Quantenausbeute von ΦCS = 14 % für langlebige ladungsgetrennte Zustände erreicht wird. In einem weiteren Abschnitt wird untersucht, ob die Bausteine der DNS als chirale Umgebung für die enantioselektive Photokatalyse geeignet sind. Mit Hilfe einer auf der Marcus-Theorie basierenden Interpretation der Messergebnisse wird die konformationsabhängige Ladungstrans- ferdynamik in Benzophenon-DNS-Dinukleotiden beschrieben. Es wird gezeigt, dass die Dinuk- leotide nicht uneingeschränkt für die enantioselektive Photokatalyse geeignet sind. Schließlich wird eine echte bimolekuare photokatalytische Reaktion untersucht. Dabei wird mit Hilfe von Flavin ein Alkohol in ein Aldehyd umgesetzt. Mit einer angepassten Datenauswer- tung werden diffusive Prozesse auf der ps-Zeitskala genau quantifiziert. Die gewonnen Informa- tionen dienen dazu, die Reaktionsbedingungen zu optimieren um über einen Triplett- Reaktionsmechanismus höhere Quantenausbeuten zu erzielen. Nachdem photoinduzierte Ladungstransferprozesse ausgiebig diskutiert wurden, liegt der Fo- kus im zweiten Teil auf der [2+2] Photocycloaddition: Als Grundlage für die Interpretation spä- terer Messungen wird zunächst die [2+2] Photocykloaddition an substituierten Chinolonen unter- sucht. Die einzelnen Reaktionsschritte der Ringbildung werden auf der Zeitskala von ps bis ns quantifiziert und charakterisiert, wobei der Triplettzustand den zentralen Zustand bildet. An- schließend wird die [2+2] Photocycloaddition an substituierten Chinolonen durch einen chiralen, auf dem organischen Chromophor Xanthon basierenden Photokatalysator initiiert. Es wird ge- zeigt, dass innerhalb des Katalysator-Substrat-Komplexes, in dem beide Moleküle einen Abstand von wenigen Ångström haben, neue elektronische Eigenschaften auftreten. Die Anregung eines neuen Zustands initiiert nicht nur die [2+2] Photocycloaddition sondern stellt auch einen neuen Sensibilisierungsmechanismus dar, der bisher in photokatalytischen Reaktion organischer Mole- küle nicht beobachtet wurde. Der Triplettzustand des Chinolons tritt hierbei nicht mehr auf. Ob sich dieser Sensibilisierungsmechanismus auch auf andere Systeme übertragen lässt, muss durch weitere Arbeiten auf diesem Gebiet geklärt werden.
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Xia, Mingjun. "Pico- and femto-second optical pulse propagation in semiconductor optical amplifiers : analysis, optimization and quantum transmission line modelling." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/7128/.
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This thesis has theoretically and experimentally investigated the ultrashort optical pulse propagation in semiconductor optical amplifiers (SOAs), which is an important topic in the optical fiber communication and optical signal processing. Some new work has been done: Firstly, effects of carrier heating on the ultrashort optical pulse propagation in quantum well SOAs are first studied taking into account the holes’ non-parabolic density of states; for bulk SOAs, an accurate and simple analytical method to study carrier heating effects is presented based on Fermi-Dirac integrals approximation. Secondly, this thesis reports a novel bias current optimization method for ultrashort optical pulse distortionless amplification in SOAs based on the newly proposed bias current relation function. Detailed theoretical and experimental work is done to analyze the relation between the optimized bias current and the parameters of the input ultrashort pulse train. Finally, a novel modelling technique-quantum transmission line modelling (Q-TLM) method is proposed by combining quantum statistic description and photon-electron dynamic interaction process description. Q-TLM is used to establish models for quantum well and quantum dot structures and analyze the dynamic performance of ultrashort optical pulse propagation in SOAs. The Q-TLM technique provides an effective method to study semiconductor optical devices.
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Moreau, Frédérick. "MONOLOGUES DE FEMM : un montage scénique de sept monologues de la littérature." Thesis, Université Laval, 2009. http://www.theses.ulaval.ca/2009/26464/26464.pdf.
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Borowiec, Anita. "New acrolein production route starting from alcohols mixtures over FeMo-based catalysts." Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10153/document.
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L'acroléine est le plus simple des aldéhydes insaturés, qui - en raison de sa réactivité élevée - trouve des applications comme produit intermédiaire dans l'industrie chimique (par exemple pour la synthèse d'acide acrylique et la production de méthionine (i.e. acide aminé essentiel)). Récemment, on a observé une augmentation de la demande mondiale de produits dérivés de l'acroléine, qui devrait croître de façon continue au cours des prochaines années. De nos jours, l’acroléine est obtenue par oxydation du propylène, et donc ce procédé est basé sur des ressources fossiles qui ne cessent de décroitre. Ce travail propose une nouvelle méthode de production d'acroléine à partir de matières premières renouvelables – un mélange d’alcools formé de méthanol et d'éthanol. Cette réaction a été étudiée et optimisée en travaillant sur : les conditions de réaction via l’établissement d’un plan d’expériences afin de minimiser le nombre de tests catalytiques à réaliser, les modifications de la formulation catalytique FeMoOx (i.e. différents rapports Mo / Fe, température de calcination, et l’ajout d’éléments basiques (e.g. La, Ce) pendant la synthèse) et enfin l’utilisation d’un second catalyseur pour balancer les propriétés acides-bases nécessaires à l’obtention de notre molécule cibleAcrolein is the simplest unsaturated aldehyde, which - due to its high reactivity - finds applications as an intermediate in the chemical industry (e.g., for acrylic acid and methionine production). Recently, a worldwide demand increase of acrolein derivatives was observed, which is expected to continuously grow within the next years. However, nowadays acrolein is commercially obtained by propylene oxidation, where the raw material comes from fossil resources. This work proposes a new method of acrolein production starting from renewable feedstock – methanol and ethanol mixture. This reaction was approached by reaction conditions optimization (i.e. Design of Experiment method do decrease the number of catalytic tests and save time), FeMoOx modifications (e.g. various Mo/Fe ratios, calcination temperature, and basic elements addition) and a second catalyst utilization (e.g. single commercial oxides and silica-based materials) in order to balance the acid base properties
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Finnman, Jonas, and Erik Eketorp. "Design and Manufacturing of IPM Synchronous Motor for Field Weakening Operation." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-128511.
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Rotor designs for permanent magnet synchronous machines suitable for field weakening operation have been evaluated for use with an existing drive system. The designs have been simulated with the FEM-based software Finite Element Method Magnetics (FEMM). Based on the results two different internal magnet rotors have been constructed and tested. Both designs significantly improved the speed range while maintaining or improving magnet utilisation. The implementation of field weakening algorithms in drive electronics is complex and need thorough optimisation for stable operation. Internal permanent magnet rotors are a good alternative to surface mounted designs and enables a wider speed range through improved field weakening capabilities.
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Niu, Xin. "Traction machine winding and magnet design for electric vehicles." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/traction-machine-winding-and-magnetdesign-for-electric-vehicles(df8dfe16-71cb-48ee-b270-b90b3a24617e).html.
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Work had been established for traction machine design aspects in this research. The effect of multiphase design for Permanent Magnet (PM) machine was investigated. The electromagnetic characteristics of both 3-phase and 9-phase machine, along with different magnet designs, were simulated and analyzed by using the program developed during the process. The software used were FEMM and MATLAB. The iron loss for different designs was established, based on the analytical flux density obtained by 2-D stepping FEA method. The harmonic of flux waveform and rotating field were also considered for difference areas in the machine models. The prediction was compared with experimental data collected in open circuit. The simulation result shown that there was a minimum 4% torque gain and noticeable less torque ripples for 9-phase machine, comparing with 3-phase one, with the same excitation phase current. The embedded magnet rotor design was suggested to monitor the demagnetization of each magnet closely, since some area of the magnet could be demagnetized even when the working point of magnet was well distance away from the nonlinear region of its characteristic. There were about 6% less iron loss was produced in 9-phase model than 3-phase model. The implemented method for calculating iron loss was more accurate within 3500 rpm rotor speed comparing with other approaches.
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Dos, Santos Patricia Coutinho. "The Biosynthesis and Function of Nitrogenase Metalloclusters." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/29851.
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Nitrogenase catalyzes the biological reduction of N2 to ammonia (nitrogen fixation). The metalloclusters associated with the nitrogenase components include the [4Fe-4S] cluster of the Fe protein, and the P-cluster [8Fe7S] and FeMo-cofactor [7Fe-9S-Mo-X-homocitrate], both contained within the MoFe protein. These metal-complexes play a vital role in enzyme activity during electron transport and substrate reduction. It is known that the FeMo-cofactor provides the site of substrate reduction, but the exact site of substrate binding remains a topic of intense debate. Some models for the substrate binding location favor the molybdenum atom, while other models favor one or more iron atoms within FeMo-cofactor. We have shown that the a-70 residue of the MoFe protein plays a significant role in defining substrate access to the active site: a-70 approaches one 4Fe-4S face of the FeMo-cofactor. Substitutions at this position alter enzyme specificity for reduction of alternative alkyne substrates. These altered MoFe proteins and alternative alkyne substrates, such as propargyl alcohol, were used to trap an intermediate during substrate reduction. Further studies involving the effect of pH on substrate reduction of these altered MoFe proteins pinpointed the location of the bound substrate-derived intermediate on the FeMo-cofactor to a specific Fe atom, designated Fe6.
In addition to understanding how substrates are bound and reduced at the active site, understanding how these clusters are biologically assembled is a second point of interest. Inactivation of NifU or NifS has been shown to affect the activity of both nitrogenase components. NifS is a cysteine desulfurase that provides the sulfur for cluster formation and NifU serves as a molecular scaffold during [Fe-S] cluster assembly. Genetic and biochemical experiments involving amino acid substitutions within the N-terminal and C-terminal domains of NifU indicate that both domains can separately participate in nitrogenase-specific [Fe-S] cluster formation. Furthermore, the NifU and NifS protein appear to have specialized functions in the maturation of metalloclusters of nitrogenase and cannot functionally replace the isc [Fe-S] cluster system used for the maturation of other [Fe-S] proteins. These results indicate that, in certain cases, [Fe-S] cluster biosynthetic machineries have evolved to perform only specialized functions.Ph. D.
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Goodwin, Paul Joshua. "Biosynthesis of the Nitrogenase FeMo-cofactor from Azotobacter vinelandii: Involvement of the NifEN complex, NifX and the Fe protein." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/11135.
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The iron-molybdenum cofactor (FeMo-cofactor) of nitrogenase is the subject of one the most intensive biochemical/genetic detective cases of modern science. At the active site of nitrogenase, the FeMo-cofactor not only represents the heart of biological nitrogen fixation, but its synthesis also serves as a model for complex metallocluster biosynthesis. Research in the Dean Lab is focused on furthering the understanding of Fe-S cluster biosynthesis in the nitrogenase enzyme system.
Throughout the years, scientists from a broad range of disciplines have focused their intellectual might on deciphering not only the chemistry of the FeMo-cofactor, but also the biosynthesis of this unique metallocluster. Recent advances in the study of FeMo-cofactor biosynthesis have produced considerable insight regarding the complex series of biological reactions necessary for the synthesis of this metallocluster. The work contained within this dissertation represents my efforts to further the understanding of FeMo-cofactor biosynthesis.
The concept of a molecular scaffold in FeMo-cofactor biosynthesis is generally accepted in the field of nitrogenase. Previous work has implicated the products of nifE and nifN as providing the assembly site for FeMo-cofactor synthesis. Researchers were able to purify this molecular scaffold, commonly referred to as the NifEN complex, however, detailed characterization was precluded by the inability to obtain sufficient quantities of NifEN. In an effort to fully characterize the NifEN complex, we initiated a gene fusion approach for the high level production NifEN. In addition to gene fusion, a poly-histidine tag was incorporated into NifEN, allowing purification through the application of immobilized metal-affinity chromatography (IMAC). NifEN obtained in this way was characterized using a variety of biophysical techniques and found to contain two [4Fe-4S] clusters in each NifEN tetramer. These clusters were also shown to be completely ligated by cysteine residues. With the information obtained from this study, it is concluded that the [4Fe-4S] clusters of the NifEN complex are likely to play either a structural or a redox role rather than being transferred and becoming incorporated into the FeMo-cofactor.
In addition to the biophysical characterization of the NifEN complex, a separate study was started to characterize the apo-MoFe protein. In this study we used IMAC to purify a poly-histidine-tagged apo-MoFe protein produced by a nifB-deletion mutant of A. vinelandii. Using the poly-histidine fusion approach, apo-MoFe protein was obtained in sufficient quantities for detailed catalytic, kinetic and spectroscopic analyses. This multidisciplinary approach confirmed that apo-MoFe protein contained intact P clusters and P cluster environments, as well as the ability to interact with the Fe protein. It was also shown for the first time that this tetrameric form of purified apo-MoFe protein could be activated by the addition of preformed FeMo-cofactor.
The NifEN complex was further characterized to investigate the presence of bound FeMo-cofactor intermediates. NifEN purified by IMAC is produced in the absence of the nitrogenase structural genes (nifHDK). In this genetic background, it is believed that the FeMo-cofactor biosynthetic machinery will become obstructed with unprocessed FeMo-cofactor intermediates, such as the Fe-S precursors of FeMo-cofactor, NifB-cofactor. Previous work indicated that NifEN can exist in either a charged or discharged form, based on the presence or absence of the FeMo-cofactor precursor, NifB-cofactor. EPR and VTMCD spectroscopies showed the presence of a new paramagnetic signal associated with NifEN that is believed to be in the charged or precursor bound state. This represents the first spectroscopic evidence for a precursor to the FeMo-cofactor. Furthermore, an interaction of NifEN and NifX was examined by size exclusion chromatography. From this study, NifX exhibited the capacity to bind a chromophore, presumably an FeMo-cofactor precursor, from the NifEN complex. NifX was also capable of binding to isolated FeMo-cofactor and the FeMo-cofactor precursor, NifB-cofactor.
Finally, preliminary investigations involving interaction between the Fe protein and NifEN were initiated. Recent findings indicate that NifEN and the Fe protein have the capacity to interact specifically with one another. The interaction of NifEN and Fe protein appears to be dependent on the association of FeMo-cofactor precursor with NifEN. The NifEN complex also has the capacity to accept electrons from the Fe protein in a MgATP dependent manner. The ability of NifEN to accept electrons from the Fe protein may be involved in the role of Fe protein in FeMo-cofactor biosynthesis.Ph. D.
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Meyer, Tricia L. "Strategies for Obtaining High-quality Sr2FeMoO6 Films Grown via Pulsed Laser Deposition." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1337021398.
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Gröenberg, Karin L. C. "Exploring the interactions of the nitrogenase cofactor." Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389678.
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Strandberg, Thomas. "Vuxna med förvärvad traumatisk hjärnskada - omställningsprocesser och konsekvenser i vardagslivet : En studie av femton personers upplevelser och erfarenheter av att leva med förvärvad traumatisk hjärnskada." Doctoral thesis, Örebro University, Department of Health Sciences, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-623.
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The overall purpose of this study is to illuminate the changeover process experienced by individuals who as adults acquired a traumatic brain injury (TBI), to increase the knowledge and the understanding of this process, and describe the meaning of support in every day life.
Persons who acquired a TBI as adults were administered a semi-structured interview covering six areas: consequences of TBI, family and social networks, working life and occupation, life-changes, support from society and everyday life. The interviews were qualitative and in-depth. A total of 15 informants participated, aged between 19-53 years when injured. Data were structured and underwent two phases of analysis. In the first phase, data underwent latent content analysis, underpinned by a hermeneutic approach, and in the subsequent phase, reanalysed within a framework derived from the theory of social recognition.
Findings from the first phase of inductive analysis elicited key themes: (i) the meaning of care, a question of formal and/or informal support; (ii) the meaning of action, a question of activity versus inactivity; (iii) autonomy, a question of dependence versus independence; (iv) social interaction, a question of encounter and/or treatment; (v) the theme of changes, a question of process versus stagnation; and (vi) emotions, an oscillation between hope versus hopelessness. After the construction of the six themes each of them were, through a discursive analysis, connected with theories, earlier studies in the field of brain injuries and important interview quotations from the empirical material. During this phase, an interest developed to study the material from a new theoretical point of view. The second phase of analysis therefore involved the development of a framework derived from Honneth’s (1995) theory of social recognition. The central construct of ‘recognition’ was analysed from three different dimensions proposed by Honneth: the individual dimension, the legal dimension, the value dimension. Using this framework, the data were reanalysed. The scientific term for this process of re-contextualisation and re-description of data is abduction inference.
Reported consequences were negative as well as positive. Significant others (e.g. next of kin) had an important function as a driving force for training and preparation for life-situation after injury. A majority of the informants were satisfied with support from society, such as hospital-care, rehabilitation and community support. Such support, initially, proceeded without problems but as time passed, the responsibility shifted to the person with TBI to take the initiative in arranging longer-term services. Long-term support which addresses physical, cognitive as well as psychosocial consequences of the TBI is important for outcomes. The majority of the informants had difficulties in returning to working life after the injury. The outcomes and recovery seemed to be a prolonged process, probably never ending, but which gradually over time becomes integrated as a part of life. The informants gave varying accounts of the extent to which they experienced social recognition.
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Strandberg, Thomas. "Vuxna med förvärvad traumatisk hjärnskada - omställningsprocesser och konsekvenser i vardagslivet : en studie av femton personers upplevelser och erfarenheter av att leva med förvärvad traumatisk hjärnskada /." Örebro : Örebro universitet : Universitetsbiblioteket, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-623.
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Brookes, Catherine. "New insights on the selective oxidation of methanol to formaldehyde on FeMo based catalysts." Thesis, Cardiff University, 2015. http://orca.cf.ac.uk/84633/.
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The selective oxidation of methanol has been studied in detail, with particular focus on gaining insights into the surface active sights responsible for directing the selectivity to formaldehyde. Various Fe and Mo containing oxides have been investigated for their reactivity with methanol, to gain an understanding of the different roles of these components in the industrial catalyst employed, which is a mixed phase comprised of MoO3 and Fe2(MoO4)3. Catalysts have primarily been tested through using TPD (temperature programmed desorption) and TPPFR (temperature programmed pulsed flow reaction). The reactivity of Fe2O3 is dominated by combustion products, with CO2 and H2 produced via a formate intermediate adsorbing at the catalyst surface. For MoO3 however, the surface is populated by methoxy intermediates, so that the selectivity is almost 100 % directed to formaldehyde. When a mixture of isolated Fe and Mo sites co-exist, the surface methoxy becomes stabilised, resulting in a dehydrogenation reaction to CO and H2. CO and CO2 can also be observed on Mo rich surfaces, however here a consequence of the further oxidation of formaldehyde, through a linear pathway. TPD and DRIFTS identify these intermediates and products forming. Since the structure of the industrial catalyst is relatively complex, in that it contains both MoO3 and Fe2(MoO4)3, it is difficult to identify the active site for the reaction with methanol. A novel approach to understanding this further, has involved the synthesis of a series of MoOx modified Fe2O3 catalysts in an attempt to make core-shell oxidic materials of the type MoOx/Fe2O3. Various monolayer loadings are investigated. It is conclusively shown that for all coverages the Mo stays in the surface region, even after annealing to high temperatures, only reacting with the iron oxide surface when the material is annealed above 400 ̊ C. From drying at 120 ̊ C to calcining at 500 ̊ C, the Mo converts from a MoO3-like octahedral layer to Fe2(MoO4)3, with Mo in a tetrahedral structure. Although changes in the Mo phase are clearly evident, it is shown that for all catalysts a one monolayer equivalent of amorphous octahedral MoOx also remains at the surface, regardless of the calcination temperature employed. It is this layer which is deemed as the surface active layer, since all catalysts at varying monolayer overages and anneal temperatures show a similar reaction with methanol. This overlayer is unique, and is suggested to be comparable to the surface terminating layer in bulk catalysts such as Fe2(MoO4)3. Successive work involved studying the reactivity of this upper layer, with suggestions of a two site Mo-Mo surface species forming on adsorption of methanol. Concluding work involves an investigation into the redox properties of Fe2(MoO4)3, to address the significance of this mixed oxide in commercial materials. Fe2(MoO4)3 forms the majority of the industrial catalyst, and although it shows a superior performance in terms of its activity, it cannot compete with the near 100 % selectivity of MoO3 to formaldehyde. Other supports have been trialled for their performance under reaction with methanol. It is shown that Fe2(MoO4)3 has increased bulk lattice oxygen mobility. Under normal reaction conditions, the reaction is carried out aerobically. However if oxygen supplies are restricted, Fe2(MoO4)3 is able to demonstrate a satisfactory performance above 300 ̊ C, as lattice oxygen is able to replace lost surface oxygen. This can continue for some time, until reduced phases containing Mo(IV) form. At this point formaldehyde selectivity drops, matched by a rise in CO production. High oxidation states are crucial to catalyst performance, with the reaction continuously cycling between Mo(VI) and Mo(VI), with a very short lifetime for the Mo(IV) species.
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Maxwell, Deborah Bolin. "Iron Molybdenum Cofactor: Catalyst in Dihydrogen Production and NifEN's Role in the FeMo-co Biosynthetic Pathway." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5432.
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Humankind's tremendous industrial and technological progress over the last two centuries has been driven by the natural abundance and availability of fossil fuels. As those reserves deplete, the prudent course of action would be to develop other readily available fuel sources. Some research efforts using biomolecules involve the hydrogenases and nitrogenases with the goal of evolving dihydrogen. At the nitrogenase active site, the iron-molybdenum cofactor (FeMo-co) catalyzes the reduction of dinitrogen and protons to form ammonia and dihydrogen. Toward the goal of producing dihydrogen passively as an alternative fuel, a novel advanced material has been developed. CdSe nanoparticles complexed with FeMo-co, in both aqueous and organic solvent systems showed complex formation. When the system was interrogated by EPR spectroscopy, evidence of electron transfer was observed. The CdSe-MSA?NafY?FeMo-co system when illuminated with visible light evolved dihydrogen consistently in four different experimental sets under the same reaction conditions. NifEN protein plays an important role in the biosynthesis of FeMo-co in addition to the involvement of NifU, NifS, NifB, NifX, NifH and NafY. After NifB synthesizes a FeMo-co precursor, 6-Fe NifB-co, NifEN further incorporates additional Fe, S, Mo, and (R)-homocitrate to complete the synthesis of FeMo-co. Molybdenum is provided to NifEN as its oxoanion, Mo(VI)O42-; however, in FeMo-co molybdenum is in the oxidation state of Mo(IV). EPR spectroscopic investigation of NifEN turnover samples showed a signal at g = 2.00 that was dependent on molybdate concentration. Power and temperature profiles gave evidence that the g = 2.00 EPR signal was distinct from the Fe-S clusters in NifEN. The species observed at g = 2.00 was assigned to the reduction of Mo(VI) to Mo(V). How to utilize the effectiveness of FeMo-co and complex it to photoactive materials for the purpose of evolving dihyrogen upon illumination, thus providing a sustainable alternative energy source is one subject of this dissertation. A related subject is to gain an understanding of the biosynthetic pathway of FeMo-co by investigation of NifEN turnover experiments. This understanding should contribute towards the development of improved catalysts for meeting future energy demands.Ph.D.
Doctorate
Chemistry
Sciences
Chemistry
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CARDOSO, Jorge Amaro de Sarges. "Green markov - uma abordagem híbrida de política markoviana e simulação discreta para planejamento de alocação de usuários em redes macro-femto." Universidade Federal do Pará, 2014. http://repositorio.ufpa.br/jspui/handle/2011/6311.
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CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico
CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
O uso da comunicação de voz e dados através de dispositivos móveis vem aumentando significativamente nos últimos anos. Tal expansão traz algumas dificuldades inerentes, tais como: ampliação constante de capacidade das redes e eficiência energética. Neste contexto, vem se consolidando o conceito de Green networks, que se concentra no esforço para economia de energia e redução de CO2. Neste sentido, este trabalho propõe validar um modelo de uma política baseado em processo markoviano de decisão, visando a otimizar o consumo de energia, QoS e QoE, na alocação de usuários em redes macrocell e femtocell. Para isso o modelo foi inserido no simulador NS-2, aliando a solução analítica markoviana à flexibilidade característica da simulação discreta. A partir dos resultados apresentados na simulação, a política obteve uma economia significativa no consumo energético, melhorando a eficiência energética em até 4%, além de melhorar a qualidade de serviço em relação às redes macrocell e femtocell, demonstrando-se eficaz, de modo a alterar diretamente as métricas de QoS e de QoE.
The use of voice and data communication via mobile devices has increased significantly in recent years. This expansion brings some difficulties such as: continuous expansion of network capacity and energy efficiency. In this context, has been consolidating the concept of Green Networks, which focuses on the effort to energy saving and CO2 reduction. Thus, this paper proposes validate a model of a policy based on Markov decision process to optimize energy consumption, QoS and QoE, in the allocation of macrocell and femtocell users in networks. For this the model was inserted into the network simulator NS-2, combining the Markov analytical solution to the characteristic flexibility of discrete simulation. From the results presented in the simulation, the policy obtained significant savings in energy consumption, improving energy efficiency by up to 4%, and improve the quality of service in relation to the macrocell and femtocell networks, demonstrating effective in order to directly change the metrics of QoS and QoE.