• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 40
  • 15
  • 11
  • 5
  • 2
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 95
  • 95
  • 18
  • 16
  • 12
  • 11
  • 11
  • 11
  • 10
  • 10
  • 9
  • 9
  • 9
  • 9
  • 9
  • 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.
21

The Electrical Characteristics Of Antennas In Their Operational Environment

Afacan, Gonenc 01 December 2007 (has links) (PDF)
This thesis investigates the variations of electrical properties of linear antennas mounted on certain platforms, depending on the physical properties of that platform. In this respect, related basic antenna simulations, electromagnetic simulations from primitive to complex models of airframes, and scale model measurements were used. Firstly, electrical properties of monopoles at known environment were examined and basic analyses were performed via an electromagnetic simulation tool, named CST Microwave Studio&reg / . In addition, important aspects of simulation tool were investigated. Then, an F-4 aircraft model was used to observe the electrical characteristics of antennas mounted on it. Using 3D model of F-4 aircraft, realistic antenna placement points were assigned and monopoles were attached to those points. Alternatively, a simplified F-4 model was also used and for two different models, identical simulations were done, followed by accuracy and performance analysis between the results obtained from simplified and exact models. As the outcome of these simulations, certain parameters like impedance, antenna-to-antenna coupling and radiation pattern values were examined. Additionally, change in antennas&rsquo / electrical characteristics due to their position over the airframe was investigated. In addition, a 1:10 down-scaled and copper-plated F-4 aircraft model was obtained and equipped with identical antennas. By using the measurements done on this scale model, antenna-to-antenna coupling results of MWS&reg / were verified by measurements. Finally, advantages and disadvantages of using electromagnetic simulation tools and scale model measurements for such antenna studies were discussed.
22

Performance of suction caissons with a small aspect ratio

Chen, Ching-Hsiang, active 2013 10 February 2014 (has links)
Suction caissons with a smaller aspect (length to diameter) ratio are increasingly used for supporting offshore structures, such as wind turbines and oil and gas production facilities. The design of these stubbier foundations is usually governed by lateral loads from wind, waves, or currents. It is desired to have more physical understanding of the behavior of less slender suction caissons under cyclic lateral loading condition and to have robust design tools for analyzing these laterally loaded caissons. In this study, one-g model tests with 1:25 and 1:50 suction can foundation scale models with an aspect ratio of one are conducted in five different soil profiles: normally consolidated clay, overconsolidated clay, loose siliceous sand, cemented siliceous sand, and cemented calcareous sand. This test program involves monitoring settlements, lateral displacements (walking), tilt, lateral load and pore water pressures in the suction can during two-way cyclic lateral loading at one, three and five degrees of rotation. The model foundations are monitored during installation, axial load tests, and pullout tests. In one and two-degree (±0.5 and ±1 degree) rotation tests, the suction can does not have significant walking or settlement in all the five soil profiles after 1000 load cycles. However, more significant walking or settlement may occur at extreme conditions such as the 5-degree (±2.5 degrees) rotation tests. Gaps between the foundation wall and the soil may also form in these extreme conditions in overconsolidated clay, cemented siliceous sand, and cemented calcareous sand. Plastic limit analysis, finite element analysis, and finite difference analysis are used to evaluate the laterally loaded suction can in clay. The plastic limit analysis originally developed for more slender suction caissons appears to predict a lateral capacity close to the measured short-term static capacity of the caisson with an aspect ratio of one when undisturbed undrained shear strength of soil is used. However, this plastic limit model underestimates the long-term cyclic lateral load capacity of the caisson when the remolded undrained shear strength was used. The finite element model developed in this study can simulate the development and effect of a gap between the foundation and surrounding soil as observed in the experiments in overconsolidated clay. The lateral load-displacement response predicted by this finite element model matches well with the experimental data. Finally, finite difference analysis for a rigid caisson with lateral and rotational springs was developed by fitting the lateral load-displacement response of the suction can in clay. The calibrated p-y curves for rigid caisson are significantly stiffer and have higher ultimate resistance than the p-y curves recommended by API which is consistent with other studies. This finite difference model provides an efficient approach to analyze a laterally loaded caisson with a small aspect ratio in clay. / text
23

Large eddy simulation of high speed convergent-divergent nozzle flows

Wang, Peng C. January 2013 (has links)
Interest in developing a detailed understanding of jet plume aerodynamics has increased significantly in recent years, for both civil (noise reduction) and military (Infra-Red signature modelling) aerospace applications. Such flows are critically dependent on turbulence modelling of the jet plume shear layer mixing. Reynolds averaged Navier Stokes (RANS) CFD tends to overpredict while Large Eddy Simulation (LES) CFD underpredicts potential core length. Difficulties in LES begin with the challenge of providing accurate resolution of thin turbulent boundary layers at nozzle exit. Providing physically meaningful 3D unsteady LES inlet conditions is a challenge in nozzle flows since turbulence at nozzle inlet experiences relaminarisation, which determines the boundary layer state at nozzle exit. The present thesis addresses these challenges by developing and validating against benchmark measurements an LES approach for nozzle/plume flows based on an advanced inlet condition treatment and an improved level of Sub-Grid-Scale (SGS) modelling. A technique for synthetic inlet condition generation based on a rescaling/recycling method (R2M) for LES predictions of nozzle flows has been applied and validated in the present work. Results reveal the benefits of this method such that self-consistent, correlated turbulent structures were sustained throughout the high acceleration region associated with nozzle convergence, with the turbulence anisotropy developing in the expected manner. The LES results for velocity profile shape at nozzle exit are better than low Re RANS predictions. Use of the Smagorinsky SGS closure produced level of turbulence energy at nozzle exit significantly lesser than measured. A recently proposed SGS model by Piomelli and Guerts (PGSGS) that defines the SGS length scale based on local turbulence quantities using a mesh independent formulation was also applied to the nozzle flow test case with significant improvement in the turbulence energy development through the nozzle. The LES method is applied to a supersonic jet discharging from a rectangular convergentdivergent nozzle. Results show that the R2M technique was able to generate realistic turbulence conditions at nozzle inlet that were consistent with available measured data. Using a carefully designed mesh and the advanced PGSGS model, turbulent structures were sustained through the nozzle, enabling good prediction of the nozzle exit boundary layer state and near field development. The improved capture of shear layer turbulence enabled better predictions of shear layer growth, leading to improved capture of shock cell behaviour and potential core length.
24

Innovative daylighting systems for deep-plan commercial buildings

Garcia-Hansen, Veronica Ruth January 2006 (has links)
The use of natural light is very beneficial in office buildings because energy consumption can be reduced, and working conditions can be enhanced, which positively affect workers' health and productivity. However, bringing natural light into deep plan office buildings is not possible with simple windows or skylights, and light transport systems are necessary to bring natural light into the deep cores of buildings. Light transport systems usually need sun-tracking devices to collect natural light that are complicated, expensive and require continual maintenance. Mirrored light pipes coupled with laser cut panels (LCP) are a passive and simpler daylight transport solution and are the focus of this PhD research. The primary aim has been to improve the technology and achieve the most efficient passive solution possible through the interactive use of theoretical modelling, experimental measurements and case studies. Applications of this technology were investigated in two case studies: 1) as horizontal light pipes for daylight illumination of a high rise building proposal in the tropics; and 2) as vertical light pipes for daylight illumination of a middle-rise deep plan building proposal in a subtropical environment. In both cases, quantitative system performance under best (clear sunny sky) and worst (overcast) case scenarios was undertaken via scale model testing and mathematical modelling. The major conclusion for both case studies was that mirrored light pipe technologies, when coupled with LCP, were effective in introducing sufficient ambient light levels inside buildings and over distances > 20 m from the façade or roof. Average lux levels achieved in the space were 150 to 350 lux for the horizontal light pipes and 50 to 300 lux for vertical light pipes. However, as a passive solution, this technology has two major limitations: 1) the dependence on sun azimuth and elevation angles, which result in variations in illuminance levels during the day and the year; and potentially 2) pipe size, as pipes with a large diameter (e.g. 2 m in diameter for 20 m long pipes) are required for optimal performance, such that the large pipes may limit integration in building design. Two other solutions were assessed to circumvent these limitations to the mirrored light pipe technology: 1) a passive collector that concentrate natural light by using a fluorescent panel to reduce the size of the pipe, and 2) an active collector comprising a LCP rotating 360 degrees in a 24 hour cycle to reduce system dependence on sun azimuth and elevation angles. The low light-to-light efficiency of the fluorescent panels made them inappropriate for collecting sufficient amounts of daylight necessary for daylighting of large buildings. In contrast, the rotating LCP is a very simple active system that by rotating constantly at 15 degrees per hour, reduces the deviation angle between the panel orientation and sun azimuth angle, and significantly increased the system performance. The performance was generally better (e.g. 2.5 times better for light collection under low sun elevation angles) than the passive light pipe system with fixed LCP. However, active systems raise other issues in terms of cost-benefit in constructing, operating and maintaining such systems. Passive mirrored light pipes coupled with LCPs or simple active systems with rotating LCPs have great potential as daylight solutions for deep plan buildings as they can contribute to lowering overall energy consumption, improve workplace health and become an architectural design element. Research is still required on the implementation of the technology into buildings, but the growing trend towards 'green buildings', sustainable design and government regulations or building codes will require more daylighting use in buildings, and will motivate designers to increasingly consider and incorporate such daylighting strategies into future building designs.
25

Cálculo em elementos finitos das frequências naturais dos modos de flexão de uma linha de eixo de unidade geradora hidráulica em escala / Scaled model of hydro power rotor - finite element analysis of bending natural frequencies and mode shapes

Mazer, Thiago Tazinazzo [UNESP] 18 February 2016 (has links)
Submitted by THIAGO TAZINAZZO MAZER null (thiago.mazer@gmail.com) on 2016-03-29T01:38:47Z No. of bitstreams: 1 Mestrado_TMazer_Defesa_v5.pdf: 2788915 bytes, checksum: 06d3dd7e4de2bccbf1a112feee83a4ed (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-03-29T19:10:31Z (GMT) No. of bitstreams: 1 mazer_tt_me_guara.pdf: 2788915 bytes, checksum: 06d3dd7e4de2bccbf1a112feee83a4ed (MD5) / Made available in DSpace on 2016-03-29T19:10:31Z (GMT). No. of bitstreams: 1 mazer_tt_me_guara.pdf: 2788915 bytes, checksum: 06d3dd7e4de2bccbf1a112feee83a4ed (MD5) Previous issue date: 2016-02-18 / A evolução das unidades geradoras hidráulicas é constante, sempre visando a redução de custos, mantendo ou melhorando os fatores de desempenho já alcançados. Em consequência disso têm-se em geral máquinas menores, com velocidade de rotação mais elevada e maiores solicitações mecânicas, além de estruturas com massa otimizada e consequentemente mais flexíveis. Nesse contexto, conhecer o comportamento dinâmico dos rotores das turbinas hidráulicas e ter a capacidade de simulá-los com precisão passa a ser fundamental. No presente estudo é desenvolvido um modelo em escala representativo de uma linha de eixo rotativo de turbina hidráulica de grande porte com o objetivo de avaliar o seu comportamento dinâmico, permitindo que os resultados teóricos possam ser comparados com resultados experimentais, este último não faz parte do escopo do presente trabalho. Em uma primeira etapa as dimensões do modelo em escala são determinadas por uma análise dimensional, que permite elaborar os desenhos tanto do rotor quanto de seus suportes. Os parâmetros de rigidez dos suportes são então determinados por meio de análise estrutural estática em elementos finitos (EF). Esses parâmetros são utilizados então na análise dinâmica do rotor, também em EF, permitindo obter o diagrama de Campbell (frequências naturais e seus respectivos modos em função da rotação do eixo) e a resposta harmônica ao desbalanceamento. Diferentes valores de amortecimento e desbalanceamento são assumidos nessa análise, e suas influências no comportamento dinâmico do rotor são avaliadas e discutidas. Também são avaliados os efeitos da estrutura base que suporta os mancais (fundação) na dinâmica da máquina rotativa como um todo. Por fim uma bancada experimental foi construída, sendo que a análise experimental fica como proposta para trabalhos futuros. / The evolution of hydro power units is constant, always aiming to reduce costs while maintaining or improving performance already achieved. Consequently the sizes of the components have being reduced, while rotational speed and mechanical stresses have being increased. Also, supporting structures have being optimized in weight, becoming more flexible. In this context, it is crucial to know the dynamic behavior of the rotors of hydro power units and to have the ability to simulate them accurately. In this study a representative model of a large hydro power rotor is developed in order to evaluate its dynamic behavior, allowing the comparison between theoretical results with experimental results, the latter is not part of scope of this work. In a first stage the scale model geometry is determined by a dimensional analysis, which allows elaborate the designs of the scaled rotor and its supports. The supports stiffness parameters are then determined by static structural finite element analysis (FEA). These parameters are used in rotor dynamic analysis, also in FEA, enabling the construction of Campbell diagram (natural frequencies and their respective modes shaft rotation function) and the harmonic response to unbalance. Different values of damping and unbalance are assumed in these analyses, and their influence on the rotor dynamic behavior are evaluated and discussed. The effects of the base structure supporting the bearings (also known as foundation) on the dynamics of the rotating machine as a whole are also evaluated. Finally an experimental bench was built, however the experimental analysis is proposed for future work.
26

Evaluation of a measure for construct degree of maturity of companies as to technology management: an application of the model in the case of gradual scale SIMAP / AvaliaÃÃo de um construto para medir o grau de maturidade das empresas quanto as tecnologias de gestÃo: uma aplicaÃÃo do modelo de escala gradual no caso SIMAP / AvaliaÃÃo de um construto para medir o grau de maturidade das empresas quanto as tecnologias de gestÃo: uma aplicaÃÃo do modelo de escala gradual no caso SIMAP / Evaluation of a measure for construct degree of maturity of companies as to technology management: an application of the model in the case of gradual scale SIMAP

Maria Emanuela Ferreira Nogueira 13 April 2012 (has links)
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Com a atual competitividade e exigÃncia do mercado, as empresas buscam, cada vez mais, um elevado grau de qualidade, garantindo, assim, sua permanÃncia no mercado. Para isso procuram uma constante atualizaÃÃo de tecnologias, modelos de organizaÃÃo e gestÃo, dentre outros. A cada dia surgem novos modelos e mÃtodos de implantaÃÃo de sistemas de gestÃo, onde a qualidade à um elemento nÃo mais distintivo, mas absolutamente essencial. Neste enfoque, a logÃstica se tornou ferramenta fundamental para reduÃÃo de custos e melhoria da qualidade. Para o bom desempenho das atividades logÃsticas de uma organizaÃÃo à preciso avaliar o desempenho da mesma no mercado e uma das possibilidades de avaliaÃÃo de desempenho logÃstico à o benchmarking. O presente estudo tem como objetivo aplicar a Teoria de Resposta ao Item, em particular, o Modelo de Escala Gradual, para analisar o grau de maturidade em relaÃÃo Ãs tecnologias de gestÃo, com base no construto do Sistema de Monitoramento de Arranjos Produtivos (SIMAP), que tem como finalidade atual o benchmarking competitivo. Os dados utilizados no trabalho sÃo de natureza secundÃria, provenientes de 39 itens avaliados em 109 empresas cadastradas no SIMAP. Os resultados revelados no estudo apresentaram indicativo de que as tecnologias âMÃtodo de anÃlise de investimentoâ, âEstudos de capabilidadeâ, âProgramas participativosâ, âCusteio ABCâ, âFilosofias e Ferramentas JITâ, âTempo de setupâ, âISO 14001â e âSA8000â oferecem uma maior contribuiÃÃo para medir o grau de maturidade das empresas quanto Ãs ferramentas de gestÃo. A empresa com maior grau de maturidade, 71,99 (na escala de (Â=50, σ=10)), à uma empresa de grande porte, pertence à cadeia produtiva de alimentos e bebidas, no elo dos fabricantes de laticÃnios, cevada, Ãgua e refrigerantes, que atua no mercado regional, com produÃÃo voltada para o abastecimento da regiÃo nordeste. O menor grau de maturidade, 31,63, foi encontrado em uma empresa de pequeno porte, pertencente à cadeia produtiva da construÃÃo civil, no elo da cerÃmica vermelha como varejista, tambÃm atuando no mercado regional. / Com a atual competitividade e exigÃncia do mercado, as empresas buscam, cada vez mais, um elevado grau de qualidade, garantindo, assim, sua permanÃncia no mercado. Para isso procuram uma constante atualizaÃÃo de tecnologias, modelos de organizaÃÃo e gestÃo, dentre outros. A cada dia surgem novos modelos e mÃtodos de implantaÃÃo de sistemas de gestÃo, onde a qualidade à um elemento nÃo mais distintivo, mas absolutamente essencial. Neste enfoque, a logÃstica se tornou ferramenta fundamental para reduÃÃo de custos e melhoria da qualidade. Para o bom desempenho das atividades logÃsticas de uma organizaÃÃo à preciso avaliar o desempenho da mesma no mercado e uma das possibilidades de avaliaÃÃo de desempenho logÃstico à o benchmarking. O presente estudo tem como objetivo aplicar a Teoria de Resposta ao Item, em particular, o Modelo de Escala Gradual, para analisar o grau de maturidade em relaÃÃo Ãs tecnologias de gestÃo, com base no construto do Sistema de Monitoramento de Arranjos Produtivos (SIMAP), que tem como finalidade atual o benchmarking competitivo. Os dados utilizados no trabalho sÃo de natureza secundÃria, provenientes de 39 itens avaliados em 109 empresas cadastradas no SIMAP. Os resultados revelados no estudo apresentaram indicativo de que as tecnologias âMÃtodo de anÃlise de investimentoâ, âEstudos de capabilidadeâ, âProgramas participativosâ, âCusteio ABCâ, âFilosofias e Ferramentas JITâ, âTempo de setupâ, âISO 14001â e âSA8000â oferecem uma maior contribuiÃÃo para medir o grau de maturidade das empresas quanto Ãs ferramentas de gestÃo. A empresa com maior grau de maturidade, 71,99 (na escala de (Â=50, σ=10)), à uma empresa de grande porte, pertence à cadeia produtiva de alimentos e bebidas, no elo dos fabricantes de laticÃnios, cevada, Ãgua e refrigerantes, que atua no mercado regional, com produÃÃo voltada para o abastecimento da regiÃo nordeste. O menor grau de maturidade, 31,63, foi encontrado em uma empresa de pequeno porte, pertencente à cadeia produtiva da construÃÃo civil, no elo da cerÃmica vermelha como varejista, tambÃm atuando no mercado regional. / The current competitive and demanding market make the companies look increasingly, a high degree of quality, thus ensuring their survival. To seek this constant updating of technologies, the companies need to update their organizational management models among other systems. Each day brings new models and methods of implementation of management systems, where quality is no longer a distinctive element, but absolutely essential. In this approach, logistics has become an essential tool for reducing costs and improving quality. For the good performance of the logistics activities of an organization it is necessary to evaluate its performance in the market and the possibilities of an assessment of logistics performance is benchmarking. The present study aims to apply the Item Response Theory, in particular, the Rating Scale Model, to analyze the degree of maturity in relation to management technologies, based on the construct of the Monitoring System Productive Arrangements (SIMAP), which aims to present the competitive benchmarking. The data used in this work are of secondary nature, from 39 items valued at 109 companies registered in SIMAP. The results revealed in the study had indicated that the technology âMethod of investment analysisâ, âCapability studiesâ, âParticipatory programsâ, âCosting ABCâ, âPhilosophies and Tools JITâ, âTime setupâ, âISO 14001â and âSA8000â provide a major contribution to measure the degree of maturity of the companies regarding to the management tools. The company with the highest degree of maturity, 71.99 (in the range of (μ = 50, σ = 10)), is a midsize company, which belongs to the productive chain of food and beverage manufacturers in the link of the dairy / barley / water and soft drinks, which operates in regional market, with production geared to supply the Northeast. The smaller degree of maturity, 31.63, was found in a small business, belonging to the productive chain of construction, linked to the red ceramic as a retailer, also serving the regional market. / The current competitive and demanding market make the companies look increasingly, a high degree of quality, thus ensuring their survival. To seek this constant updating of technologies, the companies need to update their organizational management models among other systems. Each day brings new models and methods of implementation of management systems, where quality is no longer a distinctive element, but absolutely essential. In this approach, logistics has become an essential tool for reducing costs and improving quality. For the good performance of the logistics activities of an organization it is necessary to evaluate its performance in the market and the possibilities of an assessment of logistics performance is benchmarking. The present study aims to apply the Item Response Theory, in particular, the Rating Scale Model, to analyze the degree of maturity in relation to management technologies, based on the construct of the Monitoring System Productive Arrangements (SIMAP), which aims to present the competitive benchmarking. The data used in this work are of secondary nature, from 39 items valued at 109 companies registered in SIMAP. The results revealed in the study had indicated that the technology âMethod of investment analysisâ, âCapability studiesâ, âParticipatory programsâ, âCosting ABCâ, âPhilosophies and Tools JITâ, âTime setupâ, âISO 14001â and âSA8000â provide a major contribution to measure the degree of maturity of the companies regarding to the management tools. The company with the highest degree of maturity, 71.99 (in the range of (μ = 50, σ = 10)), is a midsize company, which belongs to the productive chain of food and beverage manufacturers in the link of the dairy / barley / water and soft drinks, which operates in regional market, with production geared to supply the Northeast. The smaller degree of maturity, 31.63, was found in a small business, belonging to the productive chain of construction, linked to the red ceramic as a retailer, also serving the regional market.
27

Study of the differences in the fermentative metabolism of S. cerevisiae, S. uvarum and S. kudriavzevii species

Minebois, Romain Charles Martial 04 November 2021 (has links)
Tesis por compendio / [ES] Saccharomyces cerevisiae, además de ser un importante organismo modelo en biología, es indiscutiblemente la especie de levadura más utilizada en procesos fermentativos industriales, incluyendo el sector enológico. Su capacidad de fermentar en concentraciones elevadas de azúcares, tolerar concentraciones altas de etanol y soportar la adición de sulfitos, son algunos de los factores que explican su éxito en fermentaciones vínicas. El metabolismo fermentativo de S. cerevisiae en condiciones enológicas se conoce bien gracias a una amplia bibliografía científica. En cambio, aún se sabe poco sobre el metabolismo de las especies de Saccharomyces criotolerantes, S. uvarum y S. kudriavzevii, quienes han suscitado recientemente el interés del sector vitivinícola por sus buenas propiedades fermentativas a bajas temperaturas, tales como la producción de vinos con mayor contenido en glicerol y alta complejidad aromática, llegando a veces a reducir su contenido en etanol. En este contexto, esta tesis pretende ampliar nuestros conocimientos sobre el metabolismo fermentativo de S. uvarum y S. kudriavzevii en condiciones enológicas, profundizando en el entendimiento de las diferencias existentes con el de S. cerevisiae, así como entre cepas de S. cerevisiae de distintos orígenes. Para ello, hemos utilizado varias técnicas ómicas para analizar la dinámica de los metabolomas (intra- y extracelulares) y/o transcriptomas de cepas representativas de S. cerevisiae, S. uvarum y S. kudriavzevii a alta (25 °C) y baja (12 °C) temperatura de fermentación. También, hemos desarrollado un modelo metabólico a escala de genoma que, junto a un análisis de balance de flujos, es capaz de cuantificar los flujos a través del metabolismo del carbono y del nitrógeno de levaduras en cultivo de tipo batch. Así, el conjunto de estos trabajos nos ha permitido identificar rasgos metabólicos y/o transcriptómicos relevantes para el sector enológico en estas especies. También se aporta nueva información sobre las especificidades de redistribución de flujos en la red metabólica de levaduras del género Saccharomyces acorde a la especie y las fluctuaciones ambientales que ocurren durante una fermentación vínica. / [CAT] Saccharomyces cerevisiae, a més de ser un important organisme model en biologia, és indiscutiblement l'espècie de llevat més utilitzat en processos fermentatius industrials, incloent el sector enològic. La seua capacitat de fermentar grans concentracions de sucres, tolerar concentracions altes d'etanol i suportar l'addició de sulfits, són alguns dels factors que expliquen el seu èxit en fermentacions víniques. D'aquesta manera, el metabolisme fermentatiu de S. cerevisiae en condicions enològiques està ben descrit i es beneficia d'una àmplia bibliografia científica. En canvi, poc se sap encara sobre el metabolisme de les espècies de Saccharomyces criotolerants, S. uvarum i S. kudriavzevii, els qui han recentment suscitat l'interés del sector vitivinícola per les seues bones propietats fermentatives a baixes temperatures, com ara la producció de vins amb major contingut en glicerol, alta complexitat aromàtica i arribant a vegades a reduir el seu contingut en etanol. En aquest context, aquesta tesi pretén ampliar els nostres coneixements sobre el metabolisme fermentatiu de S. uvarum i S. kudriavzevii en condicions enològiques, aprofundint en l'enteniment de les diferències existents amb el de S. cerevisiae, així també com entre ceps de S. cerevisiae de diferents orígens. Per a això, hem utilitzat diverses tècniques omiques per a analitzar la dinàmica dels metabolomes (intra- i extracelul·lars) i/o transcriptomes de ceps representatius de S. cerevisiae, S. uvarum i S. kudriavzevii a alta (25 °C) i baixa (12 °C) temperatures de fermentació. També, hem desenvolupat un model metabòlic a escala del genoma que, al costat d'una anàlisi de balanç de fluxos, és capaç de quantificar els fluxos a través del metabolisme carbonat i nitrogenat de llevats en cultius de tipus batch. Així, el conjunt d'aquests treballs ens ha permés identificar trets metabòlics i/o transcriptómics rellevants per al sector enològic en aquestes espècies. També aporta nova informació sobre les especificitats de redistribució de fluxos en la xarxa metabòlica de llevats del gènere Saccharomyces concorde a l'espècie i les fluctuacions ambientals ocorrent durant una fermentació vínica. / [EN] Saccharomyces cerevisiae, besides being an important model organism in biology, is undoubtedly the most widely used yeast species in industrial fermentation processes, including the winemaking sector. Its ability to ferment at high levels of sugars, tolerate high ethanol concentrations and withstand the addition of sulfites are some of the factors explaining its success in wine fermentation. Accordingly, the fermentative metabolism of S. cerevisiae under oenological conditions is well described and benefits from a large scientific literature. In contrast, little is known about the metabolism of the cryotolerant Saccharomyces species, S. uvarum and S. kudriavzevii, which have recently attracted the interest of the wine industry for their good fermentative properties at low temperatures, such as the production of wines with higher glycerol content, high aromatic complexity and sometimes even reduced ethanol content. In this context, this thesis aims to expand our knowledge on the fermentative metabolism of S. uvarum and S. kudriavzevii under oenological conditions, deepening our understanding of the existing differences with that of S. cerevisiae, as well as between S. cerevisiae strains of different origins. For this purpose, we have used several omics techniques to analyze the dynamics of the (intra- and extracellular) metabolomes and/or transcriptomes of representative strains of S. cerevisiae, S. uvarum and S. kudriavzevii at high (25 °C) and low (12 °C) fermentation temperatures. Also, we have developed a genome-scale metabolic model that, together with a flux balance analysis, is able to quantify fluxes through carbon and nitrogen metabolism of yeast in batch culture. Taken together, this work has allowed us to identify metabolic and/or transcriptomic traits relevant to the oenological sector in these species. It also provides new information on the specificities of flux redistribution in the metabolic network of Saccharomyces yeasts according to the species and environmental fluctuations occurring during wine fermentation. / The present work has been carried out at the Department of Food Biotechnology of the IATA (CSIC). Romain Minebois was funded by a FPI grant (REF: BES-2016-078202) and supported by projects AGL2015-67504-C3-1R and RTI2018-093744-BC31 of the Ministerio de Ciencia e Inovación awarded to Amparo Querol. / Minebois, RCM. (2021). Study of the differences in the fermentative metabolism of S. cerevisiae, S. uvarum and S. kudriavzevii species [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/176018 / TESIS / Compendio
28

Modelling horizontally loaded piles in the geotechnical centrifuge

Louw, Hendrik January 2020 (has links)
Pile foundations are extensively used to support various structures that are constructed in soft/loose soils, where shallow foundations would be considered ineffective due to low bearing capacities and large settlements. The design of these structures to accommodate lateral applied loads in particular, usually imposed by winds, water and earth pressures, has gained popularity over the past few decades. The behaviour of horizontally loaded piled foundations is a complex soil-structure interaction problem and is usually concerned with the relative stiffness between the pile and the surrounding soil, where the relative stiffness is a function of both the stiffness and properties of the pile and the stiffness of the soil. Many design assumptions and methods used for pile foundations are based on the principles observed from metal piles. This raises the question of the validity and accuracy of assumptions and methods for the use of analysing and designing reinforced concrete piles, that exhibits highly non-linear material behaviour and changing pile properties after cracking. Due to the elastic behaviour of metal sections, these methods typically only focus on the soil component of the soil-structure interaction problem, only allowing changes and non-linear behaviour of the soil surrounding the pile to take place upon load application, mostly disregarding the behaviour and response of the pile itself. The main purpose and objective of the study was to determine whether aluminium sections in a centrifuge could be used to realistically and sufficiently accurately model the monotonic and cyclic response of reinforced concrete piles subjected to lateral loading. This was observed though a number of tests conducted in a geotechnical centrifuge on scaled aluminium and reinforced concrete piles, subjected to both monotonic and cyclic loading. After conducting the tests on both the scaled aluminium and reinforced concrete piles in the centrifuge it was concluded that aluminium sections cannot be used to accurately model and predict the lateral behaviour of reinforced concrete piles. Both the scaled aluminium and reinforced concrete piles proved to model the concept of laterally loaded piles quite well regarding bending at low loads. However, even at low lateral loads, the observed response of the scaled reinforced concrete was significantly different than that observed from the scaled aluminium pile. Furthermore, as the magnitude of the applied load and bending increased, the scaled reinforced concrete pile cracked, resulting in non-linear behaviour of the section under loading, which was not the case for the scaled aluminium pile that remained uncracked. This contributed to the difference in behaviour between the piles studied, therefore, the true material behaviour and failure mechanisms involved with reinforced concrete piles were not replicated by using a scaled aluminium pile section. The non-linear behaviour of the scaled reinforced concrete pile after cracking affected both the behaviour of the pile, as well as the response of the soil surrounding the pile, in contrast with the behaviour observed from the scaled aluminium pile. / Dissertation (MEng)--University of Pretoria, 2020. / The Concrete Institute / Concrete Society of Southern Africa / WindAfrica project / Civil Engineering / MEng (Structural Engineering) / Unrestricted
29

Magnifying the Rural : Moving through the past, present and future of a social space in Västergötland

Andreasson, Jenny January 2013 (has links)
In this project I have worked with strategies at regional level, as well as with alterations to an existing building, to strengthen and celebrate rural systems in a place called Naum, in Vara municipality in Västergötland. This I've donein order to challenge the dichotomy of urban and rural. I find that urbanity is very often celebrated in the architectural discipline, and in the public debate in general. There is a strong hierarchy of spaces in the national discourse of Sweden. By focusing on a rural space that I perceive have low status and connect it to networks that reach out to other spaces, cities, and regions, I treat the urban and rural as a continuous variation rather than a fixed binary. The binary is also challenged already by people constantly moving across this scale. Most of the residents of Naum, mapped out herecommute to Vara Town, or other adjacent towns or cities to work, to go school, to go the doctor, take part in cultural events etc. This project focus on the power of rural networks, on movement, and on rural systems of cooperation, and then I am making a number of alterations at a zoomed-in scale, to offer the inhabitants a more intimate relationship to this agricultural landscape. My project operate both at the intimate scale of an existing bygdegård, which is a specifically rural community space, in Naum, as well as on the larger scale of Vara municipality.To the bygdegård I propose three small scale alterations, a sauna called the 'Storytelling Sauna' (SECTION S S) an overnight stay shelter called the 'Please Stay',and an imaginative element of a 'Wisching-Well-Ditch”. In the larger scale I propose a strategic alteration to the treatment of roadsides, to increase biodiversity and human movement. I call this alteration the 'Thriving Passages'. The project also consist of this room-installation that we are all inside of, that aim to represent the different scales and allow us to move across them, and it consists of mappings of bygdegårds in Vara municipality and in Sweden and how they are connected by human movement, as well as mappings of historical and agricultural layers of this landscape.
30

Experiments on the Response of Arch-Supported Membrane Shelters to Snow and Wind Loading

Carradine, David Marc 28 April 1998 (has links)
For many years, inflatable structures and membrane enclosed structures have proved useful for a variety of purposes, such as athletic pavilions, exhibition spaces, coliseums, and kiosks. More recently, structures that combine highly pressurized inflatable arch members with light fabric membrane coverings have been considered for use as a variation of such structural systems. The United States Army has begun to investigate pressurized arch-supported membrane shelters that would be large, lightweight, and easily erected in a short amount of time. These shelters are proposed for a variety of purposes, including aircraft hangars, vehicle maintenance shelters, and medical aid stations. The specific contribution of this study was the creation and testing of scale models to obtain a better understanding of how these structures behave under wind and snow loading conditions. Three models were constructed, one at a scale of 1:100 and two at a scale of 1:50. The 1:100 scale model represented a proposed prototypical structure 200 ft long, 75 ft wide, and 50 ft tall, with multiple arches. Of the 1:50 scale models, one model represented a structure with the same dimensions as the 1:100 scale model and the other represented a single arch from one of the proposed prototypical structures. Both of the full structural models were wind and snow load tested. The single arch model was tested under full and partial snow loading. Data from the testing were collected, tabulated, and evaluated. The experimental results are discussed, conclusions are drawn, and recommendations for further research are presented. / Master of Science

Page generated in 0.0576 seconds