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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
411

Codigestão anaeróbia de lixiviado de aterro industrial e glicerina / Anaerobic co-digestion of leaching industrial landfill and glycerin

Castro, Thiago Morais de 31 January 2018 (has links)
Submitted by Rosangela Silva (rosangela.silva3@unioeste.br) on 2018-05-30T14:15:49Z No. of bitstreams: 2 Thiago Morais de Castro.pdf: 2981699 bytes, checksum: 66cbb29086744ea891ed186377e4ec48 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-05-30T14:15:49Z (GMT). No. of bitstreams: 2 Thiago Morais de Castro.pdf: 2981699 bytes, checksum: 66cbb29086744ea891ed186377e4ec48 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-01-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The main objective of this study was to evaluate the performance of the anaerobic co-digestion of different concentrations of industrial landfill leachate associated with crude residual glycerin, in a continuous anaerobic bioreactor with a fixed-structure bed (ABFSB) in the same process of anaerobic co-digestion. In this way, co-digestion tests were carried out in laboratory scale (400 mL of useful volume), batch operated in mesophilic conditions (30 ± 1 °C), with a 30-day incubation time in which five levels of (0, 1.5, 5, 8.5, and 10%) and five food/microorganism (F/M) levels (0.3, 0.5, 1, 0, 1.5, and 1.7), adopting experimental design of the Central Composite Rotational Design (CCRD). The results indicated a significant effect on the responses: methanogenic potential, removal of organic matter in terms of COD, accumulated production of CH4, and estimation of maximum production of CH4 using the modified Gompertz model, considering a confidence interval of 95% (p <0.05). From the results and with the desirability test it was verified that the ideal mixture was 95.13% of the industrial landfill leachate with 4.87% of the crude residual (v/v) residual glycerin with F/M ratio of 1.61 to optimize the process as a function of the response variables. From this recommended combination, with approximately 5% glycerin added to the leachate (v/v), the performance of ABFSB was evaluated in the co-digestion cited. The performance of the process was evaluated in three stages: biomass adaptation, gradual increase of organic loading rate (OLR) and reduction of alkaline supplementation. After the first 48-day period, the results were favorable to the application of the bioreactor in the evaluated anaerobic co-digestion, since the system presented stable conditions regarding the operational parameters with the addition of alkalinity with sodium bicarbonate (NaHCO3) and biomass adaptation. Thus, the second stage was started with application of increasing OLR (2, 3.5, 7.1 and 11.6 gCOD L-1 d-1). In the OLR of 7.1 gCOD L-1 d-1, the process reached the maximum methane flow rate (MFR) of 7.61 LNCH4 d-1, methane (MY) yield of 0.302 LNCH4 gCODrem-1 and volumetric methane production rate (VMPR) of 2.79 LNCH4 L-1 d-1, with total COD (ERCOD) and soluble COD removal efficiencies (ERsCOD) above 90%. Thus, the condition adopted in the third was OLR of 7.1 gCOD L-1 d-1, CODaffluent of 10.68 gO2 L-1 and hydraulic holding time of 35.2 h, aiming to optimize the quantity effectively required of NaHCO3. The minimum required concentration of alkalinity supplementation was of 0.28 gNaHCO3 gDQOaffluent-1. It is concluded that alkalinity supplementation was an important factor in the stability of the bioreactor. Finally, it is evidenced that the system is promising and that the results can serve as subsidy for industrial landfills to adopt this form of co-digestion, with biogas energy use. / O objetivo principal deste trabalho foi avaliar a codigestão anaeróbia de diferentes concentrações de lixiviado de aterro industrial e glicerina inicialmente em reatores em batelada e posteriormente o desempenho do processo em biorreator anaeróbio de leito fixo ordenado (Continuous Anaerobic Bioreactor with a Fixed-Structure Bed – ABFSB) em fluxo ascedente contínuo. Foram realizados ensaios de codigestão em reatores, em escala de laboratório, operados em batelada em condições mesofílicas (30 ±1 °C), com tempo de incubação de 30 dias, quando foram testados cinco níveis de adição de glicerina ao lixiviado (v/v) (0; 1,5; 5; 8,5 e 10%) e cinco níveis de relação alimento/microrganismo (A/M) (0,3; 0,5; 1,0; 1,5 e 1,7), adotando-se planejamento experimental do tipo Delineamento Composto Central Rotacional (DCCR). Os resultados obtidos indicaram efeito significativo para as variáveis respostas: potencial metanogênico, remoção de matéria orgânica, em termos de DQO, produção acumulada de CH4 e a estimativa da produção máxima de CH4 utilizando o modelo de Gompertz modificado, considerando intervalo de confiança de 95% (p<0,05). A partir dos resultados e com o ensaio da desejabilidade foi verificado que a mistura ideal foi de 95,13% do lixiviado de aterro industrial com 4,87% da glicerina residual bruta (v/v) com relação A/M de 1,61 para otimização do processo em função das variáveis respostas. A partir desta combinação recomendada, com aproximadamente 5% de glicerina adicionada ao lixiviado (v/v), avaliou-se o desempenho do ABFSB na codigestão citada. O desempenho do processo foi avaliado em três etapas: adaptação da biomassa, aumento gradual da carga orgânica volumétrica (COV) e redução da suplementação alcalina. Na primeira etapa o sistema apresentou condições estáveis quanto aos parâmetros operacionais com a suplementação da alcalinidade com bicarbonato de sódio (NaHCO3) e adaptação da biomassa. Na segunda etapa com aplicação de COV crescentes (2; 3,5; 7,1 e 11,6 gDQO L-1 d-1). Na COV de 7,1 gDQO L-1 d-1, o processo atingiu os máximos valores de vazão de metano (MFR) de 7,61 LNCH4 d-1, rendimento de metano (MY) de 0,302 LNCH4 gDQOrem-1 e a produção volumétrica de metano (VMPR) de 2,79 LNCH4 L-1 d-1, com eficiências de remoção de DQO total (ERDQO) e DQO solúvel (ERDQOs) superiores a 90%. Na terceira etapa com o COV de 7,1 gDQO L-1 d-1, DQOafluente de 10,68 gO2 L-1 e TDH de 35,2 h, visando otimizar a quantidade efetivamente necessária de NaHCO3. A concentração mínima necessária da suplementação de alcalinidade foi de 0,28 gNaHCO3 gDQOafluente-1. Concluiu-se que a suplementação da alcalinidade foi um fator de importância na estabilidade do biorreator, ficando evidenciado que o sistema é promissor e que os resultados podem servir de subsídio para que aterros industriais adotem esta forma de codigestão, com aproveitamento energético do biogás.
412

Produção e produtividade animal em capim-marandu submetido a estratégias de pastejo rotativo e adubação nitrogenada / Animal performance and productivity on marandu palisadegrass subjected to strategies of rotational stocking management and nitrogen fertilisation

Flávia Maria de Andrade Gimenes 06 August 2010 (has links)
Experimentos em grande escala para avaliação do manejo do pastejo são raros, apesar de sua importância. O objetivo deste experimento foi avaliar metas de manejo para o capim-marandu submetido à pastejo rotativo definidas em série de experimentos de menor escala (piquetes), utilizando o nitrogênio para amplificar contrastes entre as estratégias de pastejo avaliadas. As avaliações ocorreram de fevereiro de 2009 a abril de 2010 e os tratamentos corresponderam a duas alturas pré-pastejo (25 e 35 cm) e duas doses de fertilizante nitrogenado (50 e 200 kg ha-1 ano de N) (designados como 25/50, 25/200, 35/50 e 35/200) e foram alocados às unidades experimentais (UE) segundo um delineamento de blocos completos casualizados, com quatro repetições. Cada UE foi formada por 6 piquetes de 0,5 ha cada, os quais foram manejados como mini-fazendas. Cada uma das 16 minifazendas recebeu três novilhos Nelore (média 327 kg) como animais-teste para mensuração do ganho de peso diário (GMD) e mais um número variável de animais para ajustes na taxa de lotação. A meta de altura pós-pastejo foi comum a todos os tratamentos (15 cm), porém foi permitido variar acima desse valor como forma de gerar flexibilidade e permitir a manutenção das metas de altura prépastejo. Pastos manejados na altura pré-pastejo de 25 cm apresentaram maior número de pastejos, menor intervalo de pastejo e menor período de ocupação que pastos manejados com a altura de 35 cm. Maiores valores de GMD (0,629 e 0,511kg animal-1 dia), ganho de peso por unidade de área (GP) (886 e 674 kg ha-1) e de taxa de lotação (3,13 e 2,85 UA ha-1) foram registrados nos pastos manejados com a altura pré-pastejo de 25 relativamente àquela de 35 cm, respectivamente. Por outro lado, pastos manejados com a altura pré-pastejo de 35 cm apresentaram maiores valores de massa de forragem pré (6.680 e 4.800 kg ha- 1 de MS de vivo) e pós-pastejo (4.010 e 3.320 kg ha-1 de MS de vivo) e de perdas por pastejo (24,1 e 20,3% da massa de forragem pré-pastejo) que pastos manejados com a altura de 25 cm, respectivamente. A aplicação de 200 kg ha-1 de N resultou em aumentos na porcentagem de folhas na massa de forragem póspastejo (11,9 para 15,6%), na taxa de acúmulo de forragem (29,1 para 51,9 kg ha- 1 dia-1), na taxa de lotação (2,55 para 3,44 UA ha-1), conseqüentemente, no GP (697 e 863 kg ha-1) relativamente à aplicação de 50 kg ha-1. Somente variações em estratégia de manejo do pastejo resultaram em um aumento de 31% no GP, valor maior que os 24% resultantes da aplicação de N, realçando a importância de manejo do pastejo adequado como forma de aumentar desempenho animal e produtividade do sistema. Este correspondeu às metas de pastejo rotativo caracterizadas pela altura pré-pastejo de 25 cm e de pós-pastejo de 15 cm. Nesse contexto, o uso de fertilizantes nitrogenados, irrigação e de suplementos deveriam ser considerados em experimentos futuros desta natureza como uma forma de aumentar a produção e a produtividade animal. / In spite of their importance, large scale experiments to evaluate grazing management strategies are rare. The objective of this experiment was to test targets of rotational stocking management for marandu palisadegrass defined in a series of paddock scale experiments, using nitrogen to amplify contrasts between grazing strategies evaluated. Treatments corresponded to combinations between two pre-grazing heights (25 and 35 cm) and two levels of nitrogen application (50 and 200 kg ha-1 year-1) (designated as 25/50, 25/200, 35/50 and 35/200), and were allocated to experimental units according to a complete randomised block design, with four replications. Each experimental unit was comprised of six 0.5 ha paddocks, and were managed as farmlets. Each farmlet received three Nellore steers (initial body weight of 327 kg) as test animals for measuring weight gain plus a variable number of extra steers to adjust stocking rate and allow grazing to be executed according to management specifications for individual treatments. Target post-grazing height was 15 cm, but fluctuated above that as a means to contribute to maintain target pre-grazing heights. Farmlets managed at 25 cm pre-grazing height showed larger number of grazings, shorter grazing interval and occupation period of paddocks than those managed at 35 cm. Larger values of weight gain per animal (0.629 and 0.511 kg animal-1), per unit area (886 and 674 kg ha-1) and of stocking rate (3.13 and 2.85 AU ha-1) were recorded on farmlets managed at 25 cm pre-grazing height relative to those managed at 35 cm, respectively. On the other hand, farmlets managed at 35 cm pre-grazing height showed larger values of herbage mass pre- (6680 and 4800 kg ha-1 green DM) and post-grazing (4010 and 3320 kg ha-1 green DM) and grazing losses (24.1 and 20.3% of the pre-grazing herbage mass) than those managed at 25 cm, respectively. Application of 200 kg ha-1 of N resulted in increased percentage of leaves on herbage mass post-grazing (11.9 to 15.6%), in rates of herbage accumulation (29.1 to 51.9 kg ha-1 day-1), in stocking rate (2.5 to 3.44 AU ha-1) and, consequently, in weight gain per unit area (697 to 863 kg ha-1) relative to the application of 50 kg ha-1. Grazing management alone resulted in a 31% increase in weight gain per unit area, larger than the 24% increase generated by N application, highlighting the importance of adequate grazing management to increase animal performance and systems productivity. This corresponded to targets of rotational stocking management corresponding to 25 cm of pre-grazing height and 15 cm of post-grazing height. In this context, nitrogen fertiliser, irrigation and use of supplements should be considered in future experiments of this nature as a means of augmenting animal production and productivity.
413

Dinâmica do crescimento do consórcio trevo-persa e azevém anual sob diferentes intervalos de desfolhas

Sganzerla, Daiane Cristina 11 January 2013 (has links)
Made available in DSpace on 2014-08-20T14:38:47Z (GMT). No. of bitstreams: 1 tese_daiane_cristina_sganzerla.pdf: 1882299 bytes, checksum: 309cae7dd279a55786ba5efa8ee79f7a (MD5) Previous issue date: 2013-01-11 / Morphogenetic, structural and productive characteristics, were avaliated in a mixed pasture of persian clover (Trifolium resupinatum L. var. resupinatum Gib. & Belli cv. Kyambro) and italian ryegrass (Lolium multiflorum Lam cv. Comum) under different defoliation intervals. The experiment was conducted at the Embrapa Clima Temperado, Capão do Leão, RS. The treatments consisted of four defoliation intervals (determined according to the time of onset of 2,5; 3,5; 4,5 and 5,5 leaves on the persian clover) in two years of evaluation (2009 and 2010 ). We used a complete randomized blocks, with six replications. Defoliation was performed by grazing with lactating cows of the Jersey breed, under rotational stocking. The variables analyzed included: rate of leaf appearance, phyllochron, number of live leaves, dead and senescent, sward height and plant, length of branches / tillers, dry matter production, leaf area, leaf area index and rate dry matter accumulation. Higher rates of leaf appearance were found in shorter intervals between defoliation for both clover and for ryegrass. For persian clover larger intervals provided greater number live leaves. As for ryegrass, greater live leaves found in shorter intervals between defoliation. The leaf area index of pasture and persian clover was higher in the interval of 5,5 leaves in the years 2009 and 2010. In 2009 the highest values of leaf area were obtained in intervals of 3,5 and 4,5 leaves and there was no effect of the intervals between defoliation in 2010 on this variable. Higher intervals provided higher sward height and plants height and also length of tillers and branches. The dry matter yield of persian clover was higher in 2010 while for ryegrass higher production was found in 2009, and the total dry matter production was higher in the interval of 5,5 leaves. The rate of dry matter accumulation was higher in the interval of 5,5 leaves in 2009 and in the interval of 2,5 leaves in 2010. Higher intervals between defoliation provide higher LAI values, sward height and dry matter production. Morphogenetic, structural and productive characteristics of a mixture persian clover and ryegrass are modified by defoliation intervals, demonstrating the phenotypic plasticity of the species. Are recommended defoliation intervals of to 3,5 appeared leaves in a mixed pastures of persian clover and ryegrass to enable a greater number of live leaves attached to a lower stems elongation, characteristics desirable from the standpoint of animal production. / Características morfogênicas, estruturais e produtivas foram avaliadas em uma consorciação de trevo-persa (Trifolium resupinatum L. var. resupinatum Gib. & Belli cv. Kyambro) e azevém anual (Lolium multiflorum Lam cv. Comum) sob diferentes intervalos entre desfolhas. O experimento foi realizado em área da Embrapa Clima Temperado, Capão do Leão, RS. Os tratamentos corresponderam a quatro intervalos entre desfolhas (determinados em função de tempo para o surgimento de 2,5; 3,5; 4,5 e 5,5 folhas em plantas de trevo-persa) em dois anos de avaliação (2009 e 2010). Utilizou-se o delineamento de blocos completos ao acaso, com seis repetições. A desfolha foi realizada através de pastejo, com vacas em lactação da raça Jersey, sob lotação rotativa. As variáveis analisadas incluíram: taxa de aparecimento de folhas, filocrono, número de folhas vivas, mortas e senescentes, altura do dossel e de plantas, comprimento de ramificações/perfilhos, produção de matéria seca, área foliar, índice de área foliar e taxa de acúmulo de matéria seca. Maiores taxas de aparecimento de folhas foram encontradas em menores intervalos entre desfolhas tanto para trevo quanto para azevém. Para trevo-persa maiores intervalos proporcionaram maior número de folhas vivas. Enquanto para azevém, maior número de folhas vivas foi encontrado em menores intervalos entre desfolhas em 2009 e nos maiores intervalos em 2010. O índice de área foliar do trevo+azevém e do trevo-persa foi maior no intervalo de 5,5 folhas nos anos de 2009 e 2010. No ano de 2009 maiores valores de área foliar foram obtidos nos intervalos de 3,5 e 4,5 folhas e não se observou efeito dos intervalos entre desfolha sobre esta variável em 2010. Maiores intervalos entre desfolha proporcionaram maior altura do dossel e de plantas e também maior comprimento de perfilhos e ramificações. A produção de matéria seca do trevo-persa foi maior em 2010 enquanto que para azevém maior produção foi encontrada em 2009, sendo a produção de matéria seca total maior no intervalo de 5,5 folhas. A taxa de acúmulo de matéria seca foi maior no intervalo de 5,5 folhas em 2009 e no intervalo de 2,5 folhas em 2010. Intervalos entre desfolha maiores proporcionam maiores valores de IAF, altura do pasto e produção de matéria seca. As características morfogênicas, estruturais e produtivas da consorciação trevo-persa e azevém são modificadas pelos intervalos entre desfolha, demonstrando a plasticidade fenotípica das espécies. São recomendáveis períodos de descanso de até 3,5 folhas surgidas, em consorciações de trevo-persa e azevém para possibilitar um maior número de folhas vivas associadas a um menor alongamento de caules, características desejáveis do ponto de vista da produção animal.
414

K-isomerism at high-spin beyond the fusion limit

Wheldon, Carl January 1999 (has links)
New high-K isomers have been populated in Ta and W by bombarding thick targets with pulsed 238U beams at 1600 MeV. The new inelastically excited multi-quasiparticle states include Kpi = 21/2- and 29/2- 3-quasiparticle isomers in 181Ta and Kpi = 7- and (16+) isomers in 186W. The Kpi = (16+) state in 186w has t1/2&ge;3 ms and extends the 4-quasiparticle isomer systematics beyond the limit accessible with fusion-evaporation reactions, using stable beams and targets, for the first time. In addition, a t1/2&ge;1 ms 3-quasiparticle isomeric state feeding a strongly coupled rotational band has been populated in Ta by nucleon transfer. The excitation energies of the intrinsic states are compared to predictions of blocked BCS calculations. A different study of high-K states used a radioactive 14C beam at 67 MeV to investigate the high-spin structure of Os. New rotational bands built on multi-quasiparticle states with Kpi = 5-, 7-, 9-, 10+ and 15+ are observed. The first crossing of the ground-state band at I = 14 h, is interpreted as involving a high-K t-band structure and explained using a two-band mixing model. The structure at higher angular momentum is dominated by intrinsic states, that exhibit a dramatic loss of isomerism. Potential-energy-surface calculations, with Lipkin-Nogami pairing, show these configurations to be triaxial, accounting for the breakdown in K conservation. The relation between the K projection and the total angular momentum is investigated for these non-axial states.
415

AVALIAÇÃO DE UM REATOR BIOLÓGIGO ROTATIVO DE CONTATO (RBC) APLICADO AO TRATAMENTO DE EFLUENTE DE UM ABATEDOURO DE SUÍNOS E AVES. / EVALUATION OF ROTATING BIOLOGICAL CONTACTORS (RBC) APPLIED TO THE TREATMENT OF EFFLUENT FROM A PIG AND POULTRY SLAUGHTERHOUSE

Schwerz, Bervey 14 March 2012 (has links)
With the expansion of industrial society, began a intense growth of production of waste, creating a latent issue, referring to allocate up correctly all waste generated during the manufacturing process. Specifically, the meat processing generates during its many stages a huge flow of wastewater. An alternative for the treatment of this type of waste are rotating biological contactors. This paper, has for objective, at the construction and application of a RBC to improve performance in the treatment of an industrial effluent from the slaughterhouse of pigs and poultry. It was built a reactor 4L and aerobic sludge was used as inoculum system. The analysis period amounted to 73 days. As results were obtained an efficiency of 84.46% with a removal 1.64 g DBO.m-2 and 88.3% for an HRT of 4 h and surface loading of 124 g DQO.d-1.m-2 for BOD and COD respectively, corresponding to organic matter. On removal of nutrients, the system obtained in an efficiency of 92.02% and a surface charge removed from 8.35 g Nd-1m-2 for nitrogen and 75.66% efficiency and removal of superficial 1.5 g Pd-1.m-2, for analysis of phosphorus. In summary, the RBC could efficiently treat an effluent to obtain satisfactory results in removing the organic load and nutrients. / Com a expansão da sociedade industrial, se iniciou uma geração de resíduos de forma intensa, surgindo uma questão latente, referente a destinar-se corretamente todos os resíduos gerados durante o processo industrial. Mais especificamente, o processamento de carne gera durante suas inúmeras etapas uma enorme vazão de efluentes líquidos. Uma alternativa para o tratamento deste tipo de resíduo são os reatores de biodiscos. Este trabalho tem por objetivo a construção e aplicação de um RBC para avaliar seu desempenho no tratamento de um efluente industrial proveniente do abate de suínos e aves. Foi construído um reator de 4L e utilizado lodo aeróbio como inóculo do sistema. O período de análise correspondeu a 73 dias. Como resultados foram obtidos uma eficiência de 84,46% com uma remoção de 1,64 g DBOm-2 e 88,3%, para um TRH de 4 h e carregamento superficial de 124 g DQOd-1m-2, para DBO e DQO respectivamente, correspondendo a matéria orgânica. Na remoção de nutrientes, o sistema obteve um rendimento de 92,02% e uma carga superficial removida de 8,35 g Nd-1m-2 para o nitrogênio e a eficiência de 75,66% e a remoção superficial é de 1,5 g Pd-1m-2, para as análises de fósforo total. Em resumo, o RBC conseguiu tratar de forma eficiente um efluente de forma a obter resultados satisfatórios na remoção da carga orgânica e nutrientes.
416

Orientation-dependent energy transfer in gas-surface collisions: Scattering of vibrationally excited nitric oxide from Au(111)

Bartels, Nils 07 July 2015 (has links)
<p> Meine Doktorarbeit ist ein Beitrag zum Gebiet der Reaktionsdynamik an Oberflächen. In diesem Forschungsbereich wird daran gearbeitet, ein detailliertes mikroskopisches Verständnis von chemischen Prozessen an Oberlächen zu erzielen. Fortschritt resultierte dabei häufig aus der Zusammenarbeit von experimentell und theoretisch arbeitenden Forschern und die vorliegende Arbeit führt diese Tradition weiter. Ausgangspunkt meiner Untersuchungen war eine bemerkenswerte theoretische Vorhersage, die ich experimentell überprüft habe. Dabei habe ich mehrere neue Beobachtungen gemacht, von denen ich hoffe, dass sie zu Weiterentwicklungen in der theoretischen Chemie beitragen. </p> <p> Ein aktuelles und wichtiges Thema auf das ich meine Forschung gerichtet habe, ist das Versagen der Born-Oppenheimer Näherung und die damit einhergehenden elektronisch nichtadiabatischen Energietransferprozesse an Oberflächen. Dafür habe ich das Streuverhalten von hoch schwingungsangeregtem Stickstoffmonoxid (NO) an der (111)-Oberfläche eines Goldkristalls untersucht. Dieses System war bereits vor dieser Arbeit ein bedeutendes Modellsystem für nichtadiabatische Prozesse an Oberflächen. Beim Stoß mit der Oberfläche geben die hochschwingungsangeregten NO Moleküle Schwingungsenergie an elektronische Freiheitsgrade im Metall ab. Dieser sehr effiziente Energietransfer kann nur im Rahmen eines nichtadiabatischen Effektes (Versagen der Born-Oppenheimer Näherung) erklärt werden und der aktuelle Stand der Forschung ist, dass dieser Prozess durch einen transienten Elektronentransfer (ET) von der Oberfläche zum Molekül verursacht wird. </p> <p> Gemessen habe ich Schwingungs- und Rotationsverteilungen von in verschiedenen angeregten Schwingungszuständen (<i>v</i><sub>i</sub> = 3, 11, und 16) präparierten NO Molekülen nach dem Stoß mit der Au(111) Oberfläche. Dabei wurden die einfallende Translationsenergie (<i>E</i><sub>i</sub><sup>trans</sup>=0.05 - 1 eV) und die Orientierung der Moleküle systematisch variiert. Dies sollte den Einfluss dieser Parameter auf den durch ET getriebenen Energietransfer aufzeigen, sowie generell zu einem besseren Verständnis der Gesetzmäßigkeiten beitragen, nach denen Prozesse an Oberflächen ablaufen. Um die angestrebten Experimente durchführen zu können, habe ich an der Entwicklung von zwei neuen experimentellen Methoden mitgewirkt: 1) einer Methode um polare Moleküle in einem elektrischen Feld auszurichten ( "Optische Zustandsselektion mit adiabatischer Orientierung") und 2) einer Methode für die Unterdrückung von spontaner Emission beim optischen Pumpen ("Pump-Dump-Sweep"). </p> <p> Der Einfluss der Orientierung ist sowohl drastisch als auch komplex. Für NO in <i>v</i><sub>i</sub> = 3 und 11 wird die Schwingungsrelaxation stark durch eine Ausrichtung der Moleküle mit dem N-Atom in Richtung der Oberläche gegenüber einer Ausrichtung mit dem O-Atom in Richtung der Oberfläche verstärkt. Für diese Zustände nimmt die Relaxation außerdem mit steigender einfallender Translationsenergie zu. Interessanterweise verschwinden sowohl der Einfluss der Translationsenergie, als auch der Orientierung für NO in <i>v</i><sub>i</sub> = 16 und alle Moleküle relaxieren zu niedrigeren Schwingungszuständen. Die Rotationsverteilungen der gestreuten Moleküle hängen ebenfalls stark von der einfallenden Translationsenergie, Orientierung sowie dem Schwingungszustand ab und zeichnen sich durch ausgeprägte nicht-thermische Maxima ("Rotationsregenbögen") aus. Dies ist die erste Beobachtung von Rotationsregenbögen in Molekülen, die zuvor Schwingungsenergie durch einen Stoß mit einer Oberfläche verloren haben. </p> <p> Die Messergebnisse weisen eine komplizierte Abhängigkeit von Orientierung, Einfallsenergie und Schwingungszustand auf. Trotzdem können die beobachteten Trends in der Schwingungsrelaxationswahrscheinlichkeit mit einem einfachen Modell verstanden werden, welches auf einer energetischen Barriere der zugrundeliegenden Elektronentransferreaktion basiert. Die Höhe dieser Barriere nimmt mit zunehmender einfallender Schwingungsenergie ab. Dies erklärt den Trend hin zu stärkerer Schwingungsrelaxation, wenn <i>v</i><sub>i</sub> erhöht wird. Die Änderung der Barriere erklärt auch, warum die Schwingungsrelaxation für <i>v</i><sub>i</sub> = 3 und 11 stark von der Translationsenergie beeinflusst, für <i>v</i><sub>i</sub> = 16 hingegen kaum benötigt wird. Die Barrierenhöhe wird außerdem durch eine Ausrichtung der Moleküle mit dem N-Atom in Richtung der Oberfläche verringert und führt zu einem starken Anstieg der Relaxation für diese Orientierung. </p> <p> Die experimentellen Daten aus dieser Arbeit ermöglichen einen sehr detaillierten Test für Methoden der theoretischen Chemie. Aktuelle Berechnungen zu dem untersuchten System basierend auf den Methoden der Elektronischen Reibung ("electronic friction") oder IESH ("independent electron surface hopping") scheitern bei der Vorhersage der erzeugten Schwingungsverteilungen und deren Abhängigkeiten von den Bedingungen des Streuexperiments. Ich hoffe, dass die neuen Daten als Grundlage für weitere theoretische Arbeiten dienen, um so noch tiefere Einblicke in dieses bedeutende Beispiel eines nichtadiabatischen Prozesses in der Oberflächendynamik zu erhalten. </p> <p> Ein unabhängiges Thema, welches in der vorliegenden Arbeit zusätzlich behandelt wird, ist die Erzeugung eines Molekularstrahls hoch schwingungsangeregter CO Moleküle. Dafür habe ich eine Methode entwickelt, die "Pump-pump-perturb and dump" genannt wird und auf dem optischen Pumpen in erster Näherung dipolverbotener elektronischer Übergänge beruht. Ich demonstriere die erfolgreiche Implementierung der Methode in dem bestehenden Versuchsufbau.
417

Normal variation of the tibiotalar joint in dynamic computed tomography

Lepojärvi, S. (Sannamari) 17 January 2017 (has links)
Abstract The normal tibiotalar joint is a stable structure, where only a minor widening of the ankle mortise and rotation of the fibula is caused by normal flexion-extension movements and joint loading. The most common injury mechanism is excessive external rotation of the ankle, which may induce an ankle fracture or an injury of the syndesmosis ligaments, leading to instability of the joint. Subsequent surgical fixation can cause malreduction and dysfunction of the joint by restricting normal motion, which may lead to altered tibiotalar joint loading conditions and cause long-term complications, such as osteoarthritis. In order to correctly evaluate the potential post-traumatic conditions, clinicians must know the normal movements of the fibula in the distal tibiofibular joint and the talus in the upper ankle joint under weight-bearing conditions. Until now, the normal dynamics of the syndesmosis and upper ankle joint, as well as the changes in rotations have been unknown, and the aim was to answer these questions. In the first study, the distal tibiofibular syndesmosis was assessed on non-weight-bearing computed tomography (NWBCT) scans in order to provide standardized measures of the syndesmosis in cross-sectional imaging. Second, a distal tibiofibular syndesmosis was investigated in upright weight-bearing CT (WBCT) scans in the neutral standing position and under maximal internal and external rotational stress. Third, the normal anatomy and rotational dynamics of the upper ankle joint was observed. The first study demonstrated that in axial CT imaging of the syndesmosis, the location of the fibula was either anteriorly or centrally in the tibial incisura in 88–97% of patients in both the supine position with resting ankles, and in the neutral standing position. If the fibula lies posteriorly, malreduction should be considered. The second study demonstrated that when the ankle is maximally rotated, the fibula slides back and forth in the tibial incisura with 1.5 mm total movement and a rotation of 3°, but the distal tibiofibular joint is not widened. In internal rotation of the ankle, the talus is rotated externally, the fibula moves, and the fibula moves to the posterior part of the tibial incisura in 40% of subjects. In external rotation of the ankle, the talus is rotated internally, and the fibula moves concomitantly slightly anteriorly. The results of the third study show that the talus rotates in the ankle mortise 10°, with no change in the medial clear space (MCS) and no significant lateral widening in the joint space. Minimal intrasubject variation (less than 1 mm at all measurement points) was observed in the total rotational range of motion, while in some measurements the intersubject variation was large in both supine, neutral standing, and rotational stress images. Sex or age did not affect most of the measurements; only in maximal external rotation was a minor tilting of the talus seen in the older population. These findings suggest that the contralateral ankle can and probably should be used as a reference when possible malreduction of the syndesmosis or tibiotalar ankle joint instability is suspected. / Tiivistelmä Nilkkanivel on sääriluun, pohjeluun ja telaluun muodostama kokonaisuus, jota tiiviit nivelsiderakenteet vakauttavat. Normaalisti nivelen pääasiallinen liike tapahtuu ojennus-koukistussuuntaan ja kuormittumiseen liittyen tapahtuu vain hyvin vähäistä nivelhaarukan leviämistä, eikä telaluu pääse juurikaan kiertymään. Useimmat nilkkavammat taas syntyvät kiertoliikkeessä, joka voi johtaa nivelsidevammaan ja/tai nilkkamurtumaan, johon liittyen telaluu pääsee kiertymään normaalia enemmän ulkokiertoon ja nivelhaarukka leviämään, mikä johtaa nilkan epävakauteen ja poikkeaviin kuormitusolosuhteisiin. Vamman jälkeinen kirurginen hoito taas voi aiheuttaa luisten rakenteiden asettumiseen nivelen toiminnan kannalta epäanatomiseen asentoon ja estää nilkan normaalin liikkumisen. Sekä nivelen liiallinen väljyys että virheasentoon tehty kirurginen kiinnitys voivat aiheuttaa kipua, muuttaa nivelen kuormitusolosuhteita ja johtaa nivelen toimintahäiriöihin tai ennenaikaiseen kulumiseen. Jotta vamman jälkeisiä muutoksia pystyttäisiin arvioimaan sekä sääri- ja pohjeluun välisen sidekudossidoksen eli syndesmoosin alueella että ylemmässä nilkkanivelessä tulisi terveiden nivelten normaalit liikelaajuudet ja kuormituksen aiheuttamat dynaamiset muutokset pystyä mittaamaan luotettavasti. Tämän tutkimuksen tarkoituksena oli selvittää syndesmoosialueen ja ylemmän nilkkanivelen normaali anatomia sekä maaten kuvatuista tietokonetomografia- että seisten kuvatuista kartiokeilatietokonetomografia¬tutkimuksista arvioiden. Lisäksi mitattiin molempien nivelalueiden kiertorasituksessa todettavat normaalit liikelaajuudet seisten kuvatuista kartiokeilatietokonetomografiatutkimuksista. Ensimmäinen tutkimus osoitti, että normaalisti pohjeluu sijaitsee alemman pohjesääriluunivelen etuosassa tai nivelen keskellä 88–97 %:lla tutkituista potilaista. Jos taas pohjeluu on siirtynyt nivelen takaosaan, tulee epäillä virheasentoa. Toisen tutkimuksen tulokset osoittivat, että kiertorasituksissa pohjeluu liikkuu syndesmoosialueella edestakaisin 1.5 mm ja kiertyy 3 astetta, mutta nivel ei levene sivuttaissuuntaan. Telaluun sisäkierrossa pohjeluu liukuu 40 %:lla tutkituista vapaaehtoisista koehenkilöistä syndesmoosialueen takaosaan, ja ulkokierrossa taas nivelen etuosaan. Kolmas tutkimus osoitti, että telaluu kiertyy maksimaalisen ulko- ja sisäkierron välillä 10 astetta ilman merkittävää mediaalisen tai lateraalisen nivelraon leviämistä. Kaikissa tutkimuksissa todettiin, että mikäli koehenkilöitä verrataan keskenään, samojen mittauskohtien väliset erot ovat merkittäviä. Mikäli taas verrataan saman koehenkilön molempia nilkkoja keskenään, mittauksissa ei ole merkittävää puolieroa. Ainoa mittaustulos, johon iällä tai sukupuolella oli vaikutusta, oli vanhemmassa ikäryhmässä todettu telaluun vähäinen kallistuminen maksimaalisessa ulkokierrossa. Tutkimukset tuottivat tietoa alemman pohjesääriluunivelen ja ylemmän nilkkanivelen normaalista anatomiasta ja liikkuvuuksista kiertorasituksissa tietokonetomografiatutkimuksissa. Tutkimusten perusteella todetaan, että potilaan tervettä nilkkaa kannattaa käyttää normaalianatomian vertailukohtana sekä heti vamman jälkeen mahdollisen operatiivisen hoidon tarvetta arvioitaessa että hoidon tulosta arvioitaessa.
418

Gamma spectroscopy and lifetime measurements in the doubly-odd 194tl nucleus, revealing possible chiral symmetry breaking

Masiteng, Paulus Lukisi January 2013 (has links)
Philosophiae Doctor - PhD / In the first experiment high spin states in 194Tl, excited through the 181Ta (18O, 5n) heavyion fusion evaporation reaction were studied using the AFRODITE array at iThemba LABS. The γ-γ coincidences, RAD ratios and linear polarization measurements were carried out and the previously known level scheme of 194Tl was significantly extended. A total of five rotational bands four of which are new were observed. A pair of rotational bands associated with the πh9/2 ⊗ νi−1 13/2 configuration at lower spins and with the πh9/2 ⊗ νi−3 13/2 configuration at higher spins was found and interpreted as the first possible chiral bands followed above the band crossing. The two 4-quasiparticle bands show exceptionally close near-degeneracy in the excitation energies. Furthermore close similarity is also found in their alignments and B(M1)/B(E2) reduced transition probability ratios. In the second experiment lifetimes in 194Tl were measured using the DSAM technique with the excited states in this nucleus populated through the 181Ta (18O, 5n) reaction. A total of 25 lifetimes and 30 reduced transition probabilities of magnetic dipole B(M1) and electric quadrupole B(E2) have been evaluated. Furthermore B(M1) and B(E2) reduced transition probabilities in Bands 1 and 4, which have been regarded as chiral candidates, were found to be close to each other and reveals strong splitting along spin values. This further supports the proposed chiral nature of these two bands.
419

Jets hypersoniques sondés par temps de déclin d’une cavité optique : application à l’astrophysique de laboratoire / Hypersonic jets probed by cavity ring-down spectroscopy : application to laboratory astrophysics

Suas-David, Nicolas 01 February 2016 (has links)
Les télescopes terrestres et spatiaux recueillent une énorme quantité d'informations dans le domaine infrarouge en provenance d'objets astrophysiques ''chauds'' (500-3000 K) tels que les atmosphères d'exoplanètes (Jupiters chauds), de naines brunes et les enveloppes circumstellaires d'étoiles AGBs. Cette thèse s'inscrit dans une approche d'astrophysique de laboratoire s'attachant à reproduire in situ certains aspects des conditions extrêmes rencontrées au sein de ce type d'environnements afin notamment de produire des données haute température de molécules clefs. Le nouveau dispositif mis en place à Rennes couple une Source Haute Enthalpie à un spectromètre par temps de déclin d'une cavité optique (CRDS). Le gaz étudié, chauffé dans le réservoir à une température avoisinant 2000 K, est expulsé dans une chambre basse pression au travers d'un injecteur circulaire. Le jet libre hypersonique ainsi formé est sondé en tout point et avec une très haute sensibilité. La simulation de nos écoulements stationnaires (CFD) associée à la modélisation du spectromètre a abouti à des spectres synthétiques en très bon accord avec les spectres expérimentaux. Ces données numériques ont été utilisées pour expliquer l'origine des profils de raie atypiques et plus généralement pour comprendre la structure des jets hypersoniques axisymétriques. Le cœur isentropique de ces écoulements est caractérisé par de fortes conditions hors équilibre. Une température de vibration très élevée (1350 K) et une température de rotation très basse (10 K) ont été obtenues à partir d’un jet de CO et d’argon. Ce découplage des degrés de liberté internes permet de simplifier la structure rotationnelle des spectres enregistrés et facilite l’étude des états vibrationnels excités des molécules en révélant la structure des bandes chaudes, absentes des bases de données spectroscopiques pour la plupart des molécules polyatomiques. Une approche complémentaire consiste à sonder la couche de choc produite par l'ajout d'un obstacle sur le trajet de l'écoulement. La température rotationnelle est brutalement élevée donnant ainsi accès aux transitions rotationnelles de hautes valeurs du nombre quantique J. Ces deux méthodes ont été appliquées avec succès au méthane qui joue un rôle majeur dans de nombreux environnements astrophysiques chauds. Enfin, outre la production de données spectroscopiques, ce dispositif expérimental a permis de mettre en évidence la relaxation des degrés de liberté internes du CO dans différents gaz porteurs (He et Ar) en suivant l’évolution des températures de rotation et vibration le long de l'écoulement hypersonique, aussi bien dans le cœur isentropique qu'au sein des couches limites. Ces températures sont comparées aux températures d'excitation obtenues par des méthodes ab initio afin de valider des calculs de taux de collision. Les données obtenues alimenteront à terme des bases de données, matière première au développement de codes de transfert radiatif permettant d'interpréter les observations en provenance des milieux astrophysiques ''chauds''. / A huge quantity of infrared spectra is collected by terrestrial and space telescopes from cool astrophysical objects (500-3000 K) like exoplanet (hot Jupiter) and brown dwarf atmospheres or circumstellar envelop of AGB stars. The main purpose of this thesis connected to experimental astrophysics is to provide high temperature data of key molecules by reproducing in the laboratory some aspects of such environments. A new setup built in Rennes couples a High Enthalpy Source to a highly sensitive Cavity Ring-Down Spectrometer. The gas studied, heated in the reservoir up to 2000 K, is expanded in a vacuum chamber through a circular nozzle and the resulting hypersonic jet can be probed at any location. Computational flow dynamics (CFD) calculations associated to a modeling of the infrared absorption lead to synthetic lines which are in very good agreement with the observed spectra. These numerical data were used to attribute the unusual double peak line shapes to the particular flow structure of axisymmetric hypersonic jets. Strong out-of-equilibrium conditions were evidenced in the isentropic core of the expansion. High vibrational temperature (1350 K) and rotational temperature lower than 10 K were recorded inside a jet of CO seeded in Ar. This degrees-of-freedom decoupling greatly simplifies the rotational structure of the recorded infrared spectra and unveils the presence of hot bands stemming from highly excited vibrational states which are significantly populated at high temperature. Our approach is therefore well suited for the study of rotationally cold hot bands of polyatomic molecules which are virtually missing in spectroscopic databases. A complementary approach consists in probing the shock layer formed upstream of an obstacle set perpendicularly to the hypersonic flow axis. Rotational temperature raises abruptly downstream the shock, revealing transitions associated with high J quantum numbers. These two methods were successfully applied to methane which plays an important role in numerous astrophysical environments. In addition to the acquisition of infrared spectroscopic data, the relaxation of internal degrees-of-freedom of CO seeded in different carrier gases (Ar and He) was studied by following the evolution of rotational and vibrational temperatures along the flow, in the isentropic core as well as in the peripheral viscous layers. These temperatures were compared to excitation temperatures calculated by an ab initio method in order to validate collision rates. These data will feed databases needed for the development of radiative transfer codes with a view to a better modeling of spectra observed from "hot" astrophysical environments.
420

Linear and Nonlinear Waves in Magneto-granular Phononic Structures : Theory and Experiments / Propagation d'ondes linéaires et nonlinéaires dans les structures phononiques magnéto-granulaires : théories et expériences

Allein, Florian 14 June 2017 (has links)
Les cristaux granulaires sont des arrangements périodiques ou structurés de particules élastiques en contact. Ce travail de thèse porte sur l’étude théorique et expérimentale de la propagation d’ondes élastiques à travers de telles structures.Un cristal granulaire unidimensionnel composé d’une chaîne de billes d’acier couplées à des aimants permanents fixes est tout d’abord étudié. Les forces statiques de contact entre les billes, déterminantes pour les caractéristiques de la propagation et la dispersion des ondes élastiques, sont créées par le champ magnétique des aimants. Cette configuration permet donc d’adapter la réponse dynamique du milieu en modifiant les forces magnétiques des aimants. Un modèle linéaire prenant en compte tous les degrés de liberté en translations et rotations des billes et les couplages élastiques (longitudinal, de cisaillement et de torsion) entre billes et entre les billes et un substrat est développé. Il permet d’obtenir les relations de dispersion des modes de propagation dans ce système en fonction des différents paramètresde couplage. Les expériences réalisées mettent en évidence la propagation de modes élastiques avec micro-rotation des billes et démontrent la pertinence du modèle pour la description de ce système. Plusieurs effets de dispersion intéressants sont observés et discutés, modes à vitesse de groupe nulle, modes mous. . . Dans un second temps, une étude prenant en compte les nonlinéarités de contact permet de prédire et d’observer expérimentalement la génération d’harmonique, le filtrage d’harmoniques ainsi que la conversion de modes longitudinaux vers des modes couplés de translation-rotation dans des structures granulaires s’écartant des chaines unidimensionnelles simples. Ces travaux ouvrent des perspectives intéressantes pour le contrôle d’ondes élastiques, dans le régime non linéaire, avec desstructures granulaires architecturées. / Granular crystals are periodic or structured arrangements of elastic particles in contact. This work is devoted to theoretical and experimental study of the elastic wave propagation through such structures.A one-dimensional granular crystal composed of steel spherical beads coupled to permanent magnets placed in a substrate is first studied. Static forces at the contact between beads, determining the wave propagation and dispersion characteristics, are induced by the magnetic field from the magnets. This configuration enables tuning the dynamic response of the chain by modifying the magnetic strength of the magnets. A linear model taking into account all degrees of freedom of the beads (three translations and three rotations) as well as all elastic couplings (longitudinal, shear and torsional), between the beads and between the beads and the substrate is developed. This model provides the dispersionrelations of the modes in the system for different coupling parameters. The associated experiments confirm the elastic propagation of modes with micro-rotation of beads and demonstrate the pertinence of the model for the system description. Several interesting effects on the dispersion are observed and discussed, zero group velocity modes, soft modes. . .In a second part, we take into account the nonlinearities originating from the contacts to predict and then observe experimentally the second harmonic generation. The filtering of harmonics along with conversion from longitudinal to coupled transversalrotational modes in granular structures, is also observed for a configuration deviating from simple one-dimensional chains. This work opens the way for interesting applications in elastic wave control, in the nonlinear regime, with structured granular devices.

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