Dissertations / Theses on the topic 'Geometrical influences'
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Seroto, Ngwako. "Exploration of geometrical concepts involved in the traditional circular buildings and their relationship to classroom learning." Thesis, University of Limpopo (Turfloop Campus), 2006. http://hdl.handle.net/10386/1035.
Full textTraditionally, mathematics has been perceived as objective, abstract, absolute and universal subject that is devoid of social and cultural influences. However, the new perspective has led to the perceptions that mathematics is a human endeavour, and therefore it is culture-bound and context-bound. Mathematics is viewed as a human activity and therefore fallible. This research was set out to explore geometrical concepts involved in the traditional circular buildings in Mopani district of Limpopo Province and relate them to the classroom learning in grade 11 classes. The study was conducted in a very remote place and a sample of two traditional circular houses from Xitsonga and Sepedi cultures was chosen for comparison purposes because of their cultural diversity. The questions that guided my exploration were: • Which geometrical concepts are involved in the design of the traditional circular buildings and mural decorations in Mopani district of the Limpopo Province? • How do the geometrical concepts in the traditional circular buildings relate to the learning of circle geometry in grade 11 class? The data were gathered through my observations and the learners’ observations, my interviews with the builders and with the learners, and the grade 11 learners’ interaction with their parents or builders about the construction and decorations of the traditional circular houses. I used narrative configurations to analyse the collected data. Inductive analysis, discovery and interim analysis in the field were employed during data analysis. From my own analysis and interpretations, I found that there are many geometrical concepts such as circle, diameter, semi-circle, radius, centre of the circle etc. that are involved in the design of the traditional circular buildings. In the construction of these houses, these concepts are involved from the foundation of the building to the roof level. All these geometrical concepts can be used by both educators and learners to enhance the teaching and learning of circle geometry. Further evidence emerged that teaching with meaning and by relating abstract world to the real world makes mathematics more relevant and more useful.
Escrig, Josep. "Influence of geometrical parameters on gas-liquid intermittent flows." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/47085/.
Full textZemánek, Miroslav. "Influence of Geometrical Parameters on Rupture Risk of Abdominal Aortic Aneurysm." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-233934.
Full textTeh, Lay Seong. "Library of geometric influences for stress intensity factor weight functions." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.566060.
Full textRichards, Lynn Valerie. "Children's production of locative expressions in English : the influence of geometric and extra-geometric factors." Thesis, University of Plymouth, 2001. http://hdl.handle.net/10026.1/456.
Full textSouza, Walter Rauen de. "Subsolador : a influencia de parametros geometricos na distribuição das forças." [s.n.], 1989. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257347.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola
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Mestrado
Mestre em Engenharia Agrícola
Hörberg, Thomas. "Influences of Form and Function on Spatial Relations : Establishing functional and geometric influences on projective prepositions in Swedish." Thesis, Stockholm University, Department of Linguistics, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-6867.
Full textThe present work is concerned with projective prepositions, which express the relation between two objects by referring to a direction in three-dimensional space. The projective prepositions have been regarded as expressing simple schematic relations of a geometric nature. A theory of the apprehension of projective relations can account for their meanings when they express strictly geometric relations. However, many studies have shown that the appropriateness of the prepositions also depends on the functional relation between the objects and that a number of functional factors influence the comprehension of English prepositions. This experimental study investigates if the acceptability of the Swedish prepositions över, under, ovanför and nedanför are influenced by functional factors as well, and whether acceptability judgments about över and under are more sensitive to functional influences than judgments about ovanför and nedanför, as has been shown for the corresponding English prepositions over and under, and above and below, respectively. It also investigates how the shapes and the parts of the related objects influence their functional interaction, and how the acceptability of the prepositions is in consequence influenced by the shapes of the objects. It was found that the theory of apprehension can indeed account for the acceptability of the prepositions when the relation between the objects is strictly geometric. It was further found that acceptability judgments about them are influenced by functional factors in a similar manner to the corresponding English prepositions when the objects are functionally related, although judgments about under and nedanför are not differentially influenced by these factors. Furthermore, the shapes and the parts of both of the related objects influence acceptability judgments about the prepositions in predictable manners. An extension of the theory of apprehension is suggested which can account for the functional influences indicated in the present study.
Ebermann, Marko. "Influence of geometric form deviations on operating parameters in hydrodynamic bearings." Technische Universität Chemnitz, 2018. https://monarch.qucosa.de/id/qucosa%3A21225.
Full textWeidle, William Scott. "Influence of Trimaran Geometric Parameters on Intact and Damaged Ship Stability." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/81101.
Full textMaster of Science
FILHO, GERALDO GURGEL. "INFLUENCE OF GEOMETRICAL PARAMETERS IN THE PERFORMANCE OF A CARDANICALLY SUSPENDED GYROSCOPE WITH TWO DEGREES OF FREEDOM." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1999. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=18972@1.
Full textThis paper evaluates the dynamic performance of a Two Axes Cardanic Gyroscope, based on the development of its equation of motion, considering possible manufacturing imprecisions or geometric variations on the expected geometry. Simulation results of a real guided vehicle system are used to compare with those obtained from the analytical model, in order to determine the origin of discrepancies. The simulation will allow the specification of manufacturing tolerances based on the needed precision of the dynamic behavior to keep small the overall cost. Special attention is dedicated to the influence of geometric parameters in the measurement accuracy of a two axes cardanic gyroscope, such as the eccentricity of the center of gravity of its rotor, when located inside a guided vehicle that experiences a high longitudinal acceleration and performs afterwards a specific manoeuvre. Two hypothesis for the analytical description will be explored, one considering the gyro rotor free in space and the other including the inner gimbals inertia and friction influences, while all components are considered rigid. This will show the need for a more precise model. An implementation Is presented, testing some geometric parameters, with the purpose of showing the results properly, in order to allow the mathematical model validation.
Joubert, Retief. "Influence of geometric and environmental parameters on air-cooled steam condenser performance." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4153.
Full textENGLISH ABSTRACT: Air-cooled steam condensers (ACSCs) are used in the power generation industry to directly condense turbine exhaust steam in areas where cooling water is expensive or unavailable. Large axial flow fans force ambient air through A-frame heat exchanger bundles made up of a number of rows of finned tubes through which the steam is ducted and consequently condensed during the heat transfer process to the air. The heat rejection rate or performance of an ACSC is proportional to the air mass flow rate, determined by fan volumetric performance, and the temperature difference between the finned tubes and the air. The air flow through a 30 fan ACSC (termed the generic ACSC) operating under windy conditions is solved using the commercial computational fluid dynamics (CFD) code FLUENT and the required data is extracted from the solution to calculate performance trends. It is found that fan performance is reduced due to a combination of factors. The first is additional upstream flow losses caused by separated flow occurring primarily at the leading edge of the ACSC and secondarily at the fan bellmouth inlets. The second factor leading to reduced fan performance is the presence of distorted flow conditions at the fan inlets. Hot plume air recirculation is responsible for decreased ACSC thermal performance due to increased fan inlet air temperatures. It is found that reduced fan performance is the greater contributor to reduced ACSC performance. The performance effects of varying two geometrical parameters of the generic ACSC, namely the fan platform height and the windwall height, are investigated under windy conditions. It is found that each parameter is linked to a specific mechanism of performance reduction with the fan platform height affecting fan performance and the windwall height affecting recirculation. The respective platform and windwall heights specified for the generic ACSC are found to provide acceptable performance results. To mitigate wind induced performance reductions a number of modification and additions to the ACSC are investigated. These primarily aim at improving fan performance and included the addition of walkways or skirts, the addition of wind screens beneath the fan platform, removing the bellmouth fan inlets, using different types of fans and increasing fan power. The addition of a periphery walkway and windscreens is considered to be the most practical methods of improving ACSC performance under windy conditions. The generic ACSC is modified to include both modifications and under high wind conditions the performance is found to increase measurably. The modifications also resulted in the ACSC performance being less sensitive to wind direction effects.
AFRIKAANSE OPSOMMING: Lugverkoelde kondensators word in die kragopwekkings industrie gebruik om turbine uitlaatstoom te kondenseer, veral in gebiede waar verkoelingwater duur of onbeskikbaar is. Aksiaalvloei-waaiers forseer omgewingslug deur A-raam warmteuitruiler bondels wat bestaan uit verskeie rye vinbuise. Die uitlaatstoom vloei in die vinbuise en kondenseer as gevolg van die warmteoordrag na die lug. Die warmteoordragkapasiteit van die lugverkoelde stoom kondensator is eweredig aan die massavloei-tempo van die lug, wat bepaal word deur die waaierwerkverigting, en die temperatuur verskil tussen die vinbuise en die lug. Die lugvloei deur 'n 30 waaier lugverkoelde stoom kondensator (genoem die generiese lugverkoelde stoom kondensator) onderworpe aan winderige toestande word opgelos deur die gebruik van die kommersiële vloeidinamika-pakket, FLUENT. Die nodige data is onttrek uit die oplossing en werkverrigting neigings is bereken. Dit is gevind dat waaierwerkverigting verminder as gevolg van 'n kombinasie van faktore. Die eerste is bykomende vloeiverliese wat veroorsaak word deur vloeiwegbreking wat plaasvind primêr by die voorste rand van die lugverkoelde stoom kondensator asook by die klokvormige waaier-inlate. 'n Tweede faktor wat lei tot vermindere waaierwerkverigting is die teenwoordigheid van lugvloeiversteurings by die waaier-inlate. Hersirkulering van warm pluim lug is ook verantwoordelik vir verminderde lugverkoelde stoom kondensator werkverrigting. Daar word bevind dat die vermindering in waaierwerkverrigting die grootste bydraende faktor tot vermindere lugverkoelde stoom kondensator werkverrigting is. Die effek van verandering van twee geometriese lugverkoelde stoom kondensator parameters, naamlik die waaierplatformhoogte en die windwandhoogte is ondersoek onder winderige toestande. Daar word bevind dat elk van die parameters gekoppel is aan 'n spesifieke meganisme van vermindere lugverkoelde stoom kondensator verrigting: Die waaierplatformhoogte beïnvloed waaierverrigting terwyl die windwandhoogte hersirkulering beinvloed. Daar word ook bevind dat die onderskeie waaierplatform- and windwandhoogtes van die generiese lugverkoelde stoom kondensator, van so 'n aard is dat dit aanvaarbare werkverrigting tot gevolg het. Om verlaging in werksverrigting in winderige toestande te verminder is verskeie modifikasies en byvoegings tot die lugverkoelde stoom kondensator ondersoek wat primêr gemik is op verbetering in waaierwerkverigting. Die ondersoek dek die byvoeging van 'n loopvlak, die byvoeging van windskerms onder die waaierplatform, verwydering van die klokvormige waaier-inlate, die gebruik van verskillende waaiers en die verhoging van waaierdrywing. Daar was besluit dat die byvoeging van 'n loopvlak rondom die rand van die lugverkoelde stoom kondensator en die byvoeging van windskerms die mees praktiese manier was om die lugverkoelde stoom kondensator verigting te verbeter. Die generiese lugverkoelde stoom kondensator was aangepas om beide veranderings in te sluit en meetbare verbetering in werkrigting was verkry. Die veranderings het ook meegebring dat die lugverkoelde stoom kondensator minder sensitief is vir windrigting effekte.
Ayadh, Mohammed Thabet. "Influence of the city geometric features on the two fluid model parameters." Thesis, Virginia Tech, 1986. http://hdl.handle.net/10919/45683.
Full textThe traffic flow in an urban street network is a complicated system which involves many variables. Some of these variables relate to the networkâ s geometric features; some of these variables reflect the characteristics of the vehicles, drivers and pedestrians using the network.
The Two Fluid Model was introduced to help evaluate the quality of traffic service in urban street networks. The model parameters, Tm and n, are used as a scale to compare traffic quality in two or more urban street networks. It is known that the higher the values of the two parameters in a network, the lower the quality of the network's traffic service.
This report presents material which may be used to predict the correlation between the Two Fluid Model parameters and the geometric features of a specific street network.
The Two Fluid Model parameters will be used as dependent variables in this analysis. Seven network geometric features were selected to be used as independent variables. Using linear regression techniques, the variables will be analyzed to formulate two models. One model will explain the relationship between Tm and corresponding geometric features; the other model will explain the relationship between Tm and its corresponding features. A basic understanding of these two models will allow traffic engineers to develop strategies and/or network changes to improve traffic service in a city's street network. This will especially help networks still in the planning and/or design stage.
Because the trip time per unit distance, T, is an important traffic variable for both the Two Fluid Model and in fuel consumption models, portions of this report concentrated on establishing a relation between the two models.
Master of Science
Wood, Alan Michael. "The influence of fault geometric uncertainty on hydrocarbon reservoir and simulation models." Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/5885/.
Full textMaletzke, Fabian. "Investigation Of The Influence Of Geometrical Parameters On Heat Transfer In Matrix Cooling : A Computational Fluid Dynamics Approach." Thesis, Linköpings universitet, Mekanisk värmeteori och strömningslära, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-177185.
Full textBruttomesso, Douglas Allen. "Laser ultrasonic techniques to determine the influence of geometric features on Rayleigh waves." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/21471.
Full textChoi, Taehoon. "Influence of the black-box approach on preservice teachers’ preparation of geometric tasks." Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/5439.
Full textGoswami, Ishan. "Influence of geometric and flow variations on coronary diagnostic parameters: An in-vitro study." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1367937429.
Full textPickup, Brian A. "Influence of Material and Geometric Parameters on the Flow-Induced Vibration of Vocal Folds Models." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2221.
Full textMcMurray, Jennifer Marie. "Response and Failure of Internally Pressurized Elliptical Composite Cylinders." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/79679.
Full textMaster of Science
Santos, Jorge André Piedade Pinhal dos. "The influence of geometric factors on the wall shear stress distribution in realistic human coronary arteries." Master's thesis, FCT - UNL, 2009. http://hdl.handle.net/10362/2665.
Full textBackground: Atherosclerosis is the main cause of death in the Western society. It is a geometrically focal disease, affecting preferentially vessel areas of low wall shear stress (SS), which induces the expression of atherogenic genes. To predict wall SS several options are available. Among them Computational Fluid Dynamics (CFD) simulations on 3D reconstructed coronaries using Finite Element Modeling (FEM). However, to perform CFD a 3D representation is needed. To obtain a 3D representation of the coronary under study different methods can be applied. Methods: CFD calculations were performed using FEM on ten 3D reconstructed coronary arteries by the state-of-the-art ANGUS method (biplane angiography + Intravascular Ultrasound (IVUS)). The SS outcomes of the CFD calculations were compared with SS calculated by the Poiseuille equation, and with the SS outcomes of CFD simulations of the same 3D reconstructed arteries by QCA-3D (biplane angiography – no cross-sectional information) and Straight (IVUS images stacked on a straight centerline – no curvature information) methods. Results: The Poiseuille equation did not have any sensitivity in predicting any low SS (<0.5 Pa) per cross-section. However, the average correlation coefficient between the average SS per cross section from the Angus geometries and SS based on the Poiseuille equation was r2 = 0.65 0.09. A strong correlation was obtained for the SS from the ANGUS and the Straight method, while only an average correlation was obtained between ANGUS and QCA-3D average SS. Bland-Altman analysis was performed to confirm the results agreement. The sensitivity and specificity of the QCA-3D and Straight method in predicting low and high SS was measured. Geometric factors, such as local curvature, area gradient and torsion were found to be related to the presence of SS peaks or to regions prone to plaque development. These geometric risk factors were utilized to give some guidelines on meshing optimization. Conclusions: The use of a simpler 3D reconstruction approach, such as the QCA-3D or the Straight method, in combination with the optimization of meshing based on the geometric features of the coronaries, has the potential to, in the future, bring CFD calculations of wall SS from bench to bedside.
Teixeira, Cleiton Rodrigues. "Influencia dos erros geometricos de afiação nas brocas helicoidais de aço rapido na qualidade dos furos produzidos." reponame:Repositório Institucional da UFSC, 1995. http://repositorio.ufsc.br/xmlui/handle/123456789/76274.
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Estudo das correlações existentes entre os desvios geométricos gerados nas brocas helicoidais e suas influências sobre as características do processo de furação e sobre o resultado do trabalho. Partindo-se dos desvios geométricos mais freqüentes encontrados em brocas afiadas manualmente e mecanicamente em indústrias, procurou-se reproduzir estes erros individualmente em três níveis de intensidade, permitindo assim verificar a influência destes sobre a furação. As alterações geométricas foram introduzidas uma a uma em três lotes de brocas helicoidais de aço rápido ABNT BR 7438 (DIN 338), com o diâmetro nominal de 10mm e ângulos de ponta de 106º (gumes convexos), 118º (gumes retos) e 130º (gumes côncavos) em três grupos de materiais mais empregados na indústria (alumínio 2011-73, bronze TM-23 e o aço ABNT 1020). Os ensaios foram realizados na furação maciça até uma profundidade de 25mm. Como grandezas características do processo foram medidas a força de avanço e o momento torçor e como resultado do trabalho foram determinados os desvios de circularidade e de cilindricidade, a rugosidade da parede do furo, o diâmetro médio do furo e observou-se ainda a forma dos cavacos gerados.
Cangiani, Marcos Blanco. "Influencia da geometria da junção soldada na resistencia a fadiga de ligas do sistema cobalto-cromo." [s.n.], 1998. http://repositorio.unicamp.br/jspui/handle/REPOSIP/289574.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: O propósito deste estudo foi investigar a resistência à fadiga das ligas do sistema Co-Cr (Dentorium e Degussa), submetidas ou não ao procedimento de soldagem convencional. Oitenta corpos-de-prova cilíndricos com 1,7 mm de diâmetro foram obtidos por fundição odontológica, utilizando maçarico à oxigênio e acetileno para cada tipo de liga. O procedimento de soldagem foi realizado em sessenta corpos-de prova de cada uma das ligas, sendo que vinte serviram de controle. A soldagem foi efetuada com uma liga à base de Co-Cr utilizando um maçarico à oxigênio e gás (G.L.P.). Uma distância de 0,3 mm foi padronizada entre as extremidades dos três tipos de preparo (topo a topo, chanfro de 30° e ponta de lápis) a serem soldadas. O ensaio de resistência à fadiga foi realizado numa máquina de cargas cíclicas AMSLER (Alfred J. Amsler & Co.), calibrada com carga constante de tração de 1 kgf, com os corpos-de-prova solicitados à flexão por ciclo oscilatório de 2° para cada lado. Após a fratura, o número de ciclos foi registrado e a superfície de fratura analisada sob M.EV.. Os resultados foram estatisticamente analisados usando a análise ,de variância e o teste de Tukey, nos quais verificamos que: 1 - Para a liga Dentorium, os três tipos de preparo (com solda) apresentaram valores de resistência estatisticamente semelhante entre si, porém, foram estatisticamente inferiores ao controle (sem solda); 2 - Para a liga Degussa, os preparos tipo ponta de lápis e topo a topo (com solda) mostraram valores de resistência à fadiga estatisticamente semelhantes entre si, porém, estatisticamente inferiores ao controle (sem solda) e preparo em chanfro de 30°. Nenhuma diferença estatística foi encontrada entre o controle e o preparo em chanfro de 30°; 3 -. a liga Dentorium apresentou valores de resistência à fadiga estatisticamente superior à liga Degussa, quando a solda foi efetuada no preparo tipo ponta de lápis. Nenhuma diferença estatística foi observada para o controle e os tipos de preparos em chanfro de 30° e topo a topo
Abstract: The purpose of this study was to investigate the fatigue stength of the system Co-Cr (Dentorium and Degussa), submitted or not to the procedure conventional soldering. Cylindrical eighty specimens with 1,7 mm in diameter were casted utilizing oxi-acetilene torch for each alloys kind. The soldering procedure was realizated in sixty specimens of each alloy and twenty were control. the soldering were obtained by Co-Cr welding rods and gas-oxygen torch. the solder gap selected was 0.3 mm for each prepared (top to top, chamfer 30° and pencil point). The fatigue strength was conducted in a AMSLER (alfred J. Amsler & Co. - Shaffhausen Schaweis - Switzerland) fatig~e testing machine and the specimens were sujected to a tensile load of 1 kg, and a ciclic stress amplitude of 2°. After failure, the cycles were registered and the fracture surface was examined with (S.E.M.). The results were statistically analysed using a Mann-Whitney. The results of this study indicated that: 1 - For the Dentorium alloy the three types of prepare (with solder) presented- values of strength statistically similar to each other but inferior statistically than control (without solder); 2 - For the Degu'ssa alloy, the type of prepared pencil point and top to top (with solder) showed the similar results statistically, but inferior statistically to the control (without solder) in chamfer of 30°. No statistical difference wás found between the control and prepared in chamfer of 30°; 3 - The Dentorium alloy presented resistance values of fatigue superior statistically the degussa alloy, when it solde r was made in prepare pencil point. No statistical difference was observed for the control and ty pes of prepared in chamfer 30° and top to topo
Mestrado
Materiais Dentarios
Mestre em Ciências
RODRIGUES, LARA. "INFLUENCE OF INITIAL GEOMETRIC IMPERFECTIONS ON THE INTERNAL RESONANCES AND NON-LINEAR VIBRATIONS OF THIN-WALLED CYLINDRICAL SHELLS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=35757@1.
Full textCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
A análise das ressonâncias internas em sistemas estruturais contínuos é uma das principais áreas de pesquisa no campo da dinâmica não linear. A ressonância interna entre dois modos de vibração ocorre quando a proporção de suas frequências naturais é um número inteiro. De particular importância, devido à sua influência na resposta estrutural, é a ressonância interna 1:1, geralmente associada às simetrias do sistema, a ressonância interna 1:2, devida às não linearidades quadráticas e a ressonância 1:3 decorrente de não linearidades cúbicas. A ressonância interna permite a transferência de energia entre os modos de vibração relacionados, levando geralmente a novos fenômenos com profunda influência sobre a estabilidade da resposta dinâmica. As cascas de revolução geralmente exibem ressonâncias internas devido à inerente simetria circunferencial e um denso espectro de frequência em sua faixa de frequências mais baixas. Isso pode levar não apenas a ressonâncias internas do tipo m:n, mas a múltiplas ressonâncias internas. Nesta tese é realizada a análise de múltiplas ressonâncias internas em cascas cilíndricas delgadas, em particular as ressonâncias internas de 1:1:1:1 e 1:1:2:2 são investigadas em detalhes, um tópico pouco explorado na literatura técnica. A investigação de ressonâncias internas em sistemas contínuos geralmente é realizada usando modelos discretos de baixa dimensão. Embora alguns trabalhos anteriores tenham investigado ressonâncias internas do tipo m:n em cascas cilíndricas, muitos resultados não são consistentes, uma vez que os modelos discretos derivados não consideram os acoplamentos modais devido a não linearidades quadráticas e cúbicas. Aqui, usando um procedimento de perturbação, expansões modais consistentes são derivadas para um número arbitrário de modos de interação, levando a modelos de baixa dimensão confiáveis. A precisão desses modelos é corroborada usando o método Karhunen-Loève. Finalmente, é bem sabido que pequenas imperfeições geométricas da ordem da espessura da casca têm uma forte influência na sua resposta não linear. No entanto, sua influência nas ressonâncias internas, instabilidade dinâmica e transferência de energia é desconhecida. Assim, a influência de diferentes tipos de imperfeição modal é devidamente considerada na presente análise. Utilizando os modelos discretos aqui derivados, é apresentada uma análise detalhada das bifurcações, utilizando técnicas de continuação e o critério de estabilidade de Floquet, esclarecendo a importância das ressonâncias internas nas vibrações não lineares e instabilidades de cascas cilíndricas. Os resultados também confirmam que a forma e a magnitude das imperfeições geométricas iniciais têm uma influência profunda nos resultados, permitindo ou impedindo a transferência de energia entre os modos ressonantes considerados.
The analysis of internal resonances in continuous structural systems is one of the main research areas in the field of nonlinear dynamics. Internal resonance between two vibration modes occur when the ratio of their natural frequencies in an integer number. Of particular importance, due to its influence on the structural response, is the 1:1 internal resonance, usually associated with system symmetries, the 1:2 internal resonance, due to quadratic nonlinearities, and the 1:3 resonance arising from cubic nonlinearities. The internal resonance enables the energy transfer between the related vibration modes, leading usually to new phenomena with profound influence on the stability of the dynamic response. Shells of revolution usually exhibit internal resonances due to the inherent circumferential symmetry and a dense frequency spectrum in their lower frequency range. This may lead not only to m:n internal resonances, but also multiple internal resonances. In this thesis, the analysis of multiple internal resonances in slender cylindrical shells is conducted, in particular 1:1:1:1 and 1:1:2:2 internal resonances are investigated in detail, a topic rarely found in the technical literature. The investigation of internal resonances in continuous systems is usually conducted using low dimensional discrete models. Although some previous works have investigated m:n internal resonances in cylindrical shells, many results are not consistent since the derived discrete models do not consider the modal couplings due to quadratic and cubic nonlinearities. Here, using a perturbation procedure, consistent modal expansions are derived for an arbitrary number of interacting modes, leading to reliable low dimensional models. The accuracy of these models is corroborated using the Karhunen-Loève method. Finally, it is well known that small geometric imperfections of the order of the shell thickness has a strong influence on the shell nonlinear response. However, their influence on internal resonances, dynamic instability and energy transfer is largely unknown. Thus, the influence of different types of modal imperfection is properly considered in the present analysis. Using the derived discrete models, a detail bifurcation analysis, using continuation techniques and Floquet stability criterion, is presented, clarifying the importance of internal resonances on the nonlinear vibrations and instabilities of cylindrical shells. The results also confirm that the form and magnitude of initial geometric imperfections has a profound influence on the results enabling or preventing the energy transfer among the considered resonant modes.
Sarfaraz, Wakil. "The geometric influence of domain-size on the dynamics of reaction-diffusion systems with applications in pattern formation." Thesis, University of Sussex, 2018. http://sro.sussex.ac.uk/id/eprint/79452/.
Full textMetin, Tolga. "A Parametric Study On The Influence Of Semi-rigid Connection Nonlinearity On Steel Special Moment Frames." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615725/index.pdf.
Full textAndrade, Ricardo Batista de. "Analise das influencias da geometria e do material do molde na formação da microestrutura de ligas aluminio-cobre." [s.n.], 2003. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265540.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Este trabalho apresenta uma análise experimental da influência do material e da geometria do molde em parâmetros térmicos e estruturais durante a solidificação de ligas alumínio-cobre. Para tanto placas e cilindros das ligas Al-4,5%Cu e Al-15%Cu foram solidificadas em moldes de areia e de aço. Foram obtidas, através de um sistema de aquisição de dados, as curvas de resfriamento em diferentes posições nas peças e na superfície externa dos moldes. Os resultados obtidos permitiram a determinação dos tempos de solidificação nas diferentes condições analisadas. Através de análise metalográfica foi possível determinar a influência da geometria e do material do molde na formação da macroestrutura e da microestrutura durante o processo de solidificação. Um modelo numérico para simulação do processo de solidificação em moldes maciços foi desenvolvido e otimizado. Alguns resultados obtidos com a aplicação do modelo, comparados com resultados experimentais, são apresentados
Abstract: This work presents an experimental analysis of the influence of material and geometry of mold in thermal and structural parameters during solidification of aluminum-copper alloys. Slabs and cylinders of Al-4.5wt%Cu and Al-15wt%Cu alloys were solidified in sand and steel molds. Curves of the variation of temperature in different positions in the solidifying alloy and on the external surface of the mold were determined. From the results solidification times were estimated for all cases analyzed. From metallographic analysis of the influences of geometry and mold material on macrostructure and microstructure were determined. A numerical model to analyze the solidification of alloys in massive molds was developed. Examples of the application of the model compared with experimental results are shown
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
Cingi, Guney. "The Influence Of Digital Technologies On The Interaction Of Design And Manufacturing Processes." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12606944/index.pdf.
Full textculminating with the case study of Guggenheim Museum, Bilbao.
Pardy, Shelley Ann. "Influence of balsam fir stand condition on the abundance and diversity of eastern hemlock looper, Lambdina fiscellaria fiscellaria (Guen.) (Lepidoptera: Geometridae) natural enemies." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0029/MQ62413.pdf.
Full textKarimi, Neghlani Paria. "Electron beam melting of Alloy 718 : Influence of process parameters on the microstructure." Licentiate thesis, Högskolan Väst, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-13140.
Full textBecker, Jamie Erin. "The influence of urbanization on arthropod water demand and lipid and protein consumption in mesic environments." Bowling Green State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1510869685967938.
Full textJones, Simon Philip. "Influence of modifiers on Palladium based nanoparticles for room temperature formic acid decomposition." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:873277f2-c4f7-45b7-a16d-bba064e24bee.
Full textNewberry, Simon David. "An experimental investigation into the influence of geometric properties and construction techniques on the packing density of rock armour layers for coastal engineering structures." Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406440.
Full textAblitzer, Frédéric. "Influence des paramètres mécaniques et géométriques sur le comportement statique de l’archet de violon en situation de jeu." Thesis, Le Mans, 2011. http://www.theses.fr/2011LEMA1023/document.
Full textThe bow, which is essential to produce the sound of bowed string instruments, has been little studied. The present work aims to better understand its mechanical behavior in playing situation. To this end, numerical models are developped. The stick, which is prestressed due to hair tension, is modelized by beam finite elements. A corotational formulation is adopted to take into account geometric nonlinearity. A first model (2D) concerns the in-plane behavior of the bow. It is used within a numerical study aiming at showing the influence of making and adjusting parameters on the tightened bow. A second model (3D) takes into account out-of-plane loading that makes the stick bend laterally. A non-destructive procedure to determine mechanical properties of wood and hair is proposed. It is based on an inverse method using the 2D model. As an experimental validation, numerical results obtained with the 3D model are confronted to measurement on two bows, for different settings of camber and hair tension. The effect of prestress on lateral bending stiffness is highlighted. A good agreement is observed. Thus, the model can be considered as predictive and might be used as an aid to bow making. Furthermore, the stability of a bow is a problem considered by bow makers. A phenomenological model based on a simple mechanical system is presented. It aims to give tendancies on conditions at which bifurcation or limit point instability can occur, by drawing an analogy with the bow. The numerical computation of pre- and post-critical behavior of the bow shows similar instability cases. Their possible consequences on playing and making are discussed. Finally, playing tests with musicians are carried out, focusing on the adjustment of camber and hair tension. The results tend to show the influence of the considered adjustment parameters on the assessment of playing qualities
Cavalcante, Rodrigo Gusmão. "Uma analise da influencia da curvatura do espaço em sistemas de comunicações." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261084.
Full textTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
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Resumo: Em geral, o espaço EucIidiano é utilizado no projeto e na análise de desempenho da maior parte dos sistemas de comunicações atuais. Nesta tese, verificamos que o modelo de um sistema de comunicação não necessariamente está restrito ao espaço Euclidiano, mas sim a uma variedade Riemanniana. Com isso, os sistemas de comunicaçoes podun ser analisados em um contexto mais geral, no qual constatamos que a curvatura do espaço influencia em seus desempenhos. Corno exemplo, estudamos a curvatura de meios ópticos e propomos novos perfis de guias de ondas, fibras ópticas e lentes de interesse prático. Além disso, caracterizamos a curvatura de modulações não-lineares (twisted) e verificamos que o valor máximo permitido para a energia média do ruído está relacionada ao valor da curvatura da modulação. Neste contexto, as moclulações associadas a superfícies mínimas apresentaram bons desempenhos, pois tais modulações são pontos críticos do erro quadrático médio. Mostramos também que o espaço de sinais possui métrica induzida da superfície associada à modulação. Com isso, foi possível demonstrar que os espaços de sinais com curvatura negativa são os que apresentam melhor desempenho segundo a probabilidade média de erro. Dessa forma, alguns exemplos de constelações de sinais geometricamente uniformes foram construídos e analisados em variedades Riemannianas. Finalizamos este trabalho notando que na maioria das vezes que o espaço hiperbólico é utilizado nos blocos ele um sistema ele comunicações, o desempenho desse sistema tende a se aproximar do ponto ótimo de operação
Abstract: ln general, the Euclidian space is used in the design and performance analysis in most of the current communication systems. ln this thesis, we note that the model of a communication system is not necessarily restricted to the Euclidian space, more precisely, the model can be linked to Riemannian manifolds. Thus, the communication systems could be analyed in a broader context, in which the curvature of space influence on their performance. As an example, we studied the curvature of optical medium and propose new profiles of waveguides, optical fibers and lenses of practical interest. Moreover, we have characterized the curvature of twisted modulations and found that the maximum value allowed for the average energy of noise is related to the value of the curvature of the modulation. ln this context, the modulation associatecl with minimal surfaces showed good performance, because these modulations are critical points of minimum the mean-square error. VVe show that the signal space has induced metric associated with surface of the modulation. Thus, we have shown that the signal space with negative curvature is the space where the average error probability decrease a function of the curvature. Thus, some examples of geometrically uniform signal constellations were constructecl and analyzed on Riemannian manifolds. Finally we note that most of the time that hyperbolic space is considered in blocks of a communication system, then the performance of this system tends to be closer to the optimum point of operation
Doutorado
Telecomunicações e Telemática
Doutor em Engenharia Elétrica
MELO, H. A. S. "Influencia do Comprimento e Geometria de Pinos de Fibra de Vidro no Comportamento Biomecânico de Incisivos Centrais Superiores Tratados Endodonticamente: Uma Análise Pelo Método de Elementos Finitos." Universidade Federal do Espírito Santo, 2017. http://repositorio.ufes.br/handle/10/8122.
Full textA reabilitação de dentes tratados endodonticamente representa um desafio para a odontologia e é alvo de pesquisas que buscam compreender as propriedades físicas, químicas e biomecânicas existentes entre dentes vitais e não vitais e assim indicar o complexo restaurador que seja esteticamente aceitável, com adequada função clínica e longevidade. Para dentes com extensa perda estrutural, os pinos de fibra de vidro têm sido considerados como uma alternativa aos retentores metálicos. O objetivo deste estudo foi avaliar a influência do comprimento e geometria dos pinos de fibra de vidro, sobre o comportamento biomecânico de incisivos centrais superiores tratados endodonticamente, sob uma carga de 100N aplicada a 130° com a superfície palatina, nas seguintes condições: Pinos de Fibra de Vidro (PFV) lisos (L), serrilhado (S), com profundidades de 5mm e 10mm. As diferentes formas de tratamento foram simuladas a partir do modelo computacional tridimensional de um incisivo superior hígido e analisadas qualitativamente através do método de elementos finitos. Os resultados foram avaliados pelo deslocamento dos modelos, critério de falha de von Mises e de tensão máxima principal. Os modelos PFVL5mm, PFVL10mm e PFVS5mm apresentaram um deslocamento na faixa de 0,0458mm a 0,512mm, enquanto que no modelo PFVS10mm, este deslocamento foi de 0,0116. O pino de fibra de vidro liso apresentou uma distribuição de tensões homogênea, enquanto que o pino serrilhado apresentou uma concentração de tensão na interface da geometria serrilhada. O padrão de distribuição nos modelos de pinos de fibra de vidro foi similar ao do dente hígido, porém os modelos restaurados com pinos de comprimentos maiores, resultaram em um gradiente de tensões mais uniforme e com uma maior área de distribuição. Os resultados obtidos indicaram que o pino de fibra de vidro de geometria serrilhado, em maior profundidade, influencia na redução do deslocamento do modelo. Além disso a geometria do pino de fibra de vidro influencia na concentração de tensões ao longo do pino e o aumento da profundidade desses pinos, aumenta a área de distribuição das tensões, de maneira que elas fiquem mais homogêneas.
Serra, Michele. "Influence of Metastases' Location and Size on the Strain Field Distribution in Metastatically Involved Human Vertebrae: An In Vitro Study." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19365/.
Full textSeret, Anthony. "Influence de la mise en forme sur les cinétiques de précipitation durcissante dans les superalliages base nickel Inconel® 625 et AD730™." Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEM030.
Full textNickel-based superalloys possess exceptional mechanical properties and corrosion resistance at high temperature. These mechanical properties result partly from the hardening precipitation of Ni3Nb γ″ or Ni3(Al, Ti) γ′ phases. The objective of this PhD is to better understand how forming operations of industrial parts may influence this precipitation. Two superalloys have been studied in this PhD : Inconel® 625 alloy formed a room temperature and reinforced by the γ″ phase, and AD730™ alloy hot forged and reinforced by the γ′ phase. Thermal treatments, mechanical and thermomechanical tests have been performedin order to, on the one hand, reproduce the plastic strain levels and/or the grain structure obtained at the end of industrial forming operations, and on the other hand to trigger the precipitation or the evolution of already existing precipitates. The microstructures have then been quantitatively characterizedby scanning electron microscopy regarding the grains structure, the dislocationsorganization and the precipitation state.In the Inconel® 625 alloy, the nucleation of γ″ precipitates during a thermal treatment at 650 °C is not influenced by a strain applied before, supporting the relevancy of the 650 °C temperature to bring an homogeneous hardening to industrial parts. In the AD730™ alloy, the γ′ precipitation during a cooling after a hot compression takes place sooner in unrecrystallized grains than in recrystallized grains, by elastic relaxation when nucleating. Concomitantly, the recrystallization front dissolves these γ′ precipitates present in unrecrystallized grains to avoid any incoherent γ/γ′ interface. Then γ′ precipitates reprecipitate on the recrystallization front with a coherent γ/γ′ interface in recrystallized grains, and can afterwards subdivide to reduce the global elastic energy. This PhD includes the development of specific tools : reduction of the measurement noise of EBSD maps for a more accurate assessmentof geometrically necessary dislocations densities, image analysis and precipitation model
Antonio, Graziella Colato. "Influencia da estrutura celular e da geometria da amostra na taxa de transferencia de massa do processo de desidratação osmotica de banana nanica (Musa cavendishi) e de mamão formosa (Carica papaya L.)." [s.n.], 2002. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256330.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: Neste trabalho foi estudada a transferência de massa na Banana Nanica (Musa cavendishi) e no Mamão Formosa (Carica papaya 1.) no processo de desidratação osmótica. Foi analisada a influência da geometria e estruturas celulares, para a verificação do mellior desempenho na transferência de massa. A etapa de desidratação osmótica foi conduzida com agitação constante de 80rpm e analisada através de um planejamento experimental fatorial 24-1com 3 repetições no ponto central para cada geometria estudada. As variáveis analisadas foram temperatura (30, 45 e 60°C), concentração da solução de sacarose (45, 55 e 65°Brix), concentração de ácido láctico (O, 0,05, 0,1M), e geometria da amostra (placa plana e cubo). As respostas analisadas foram perda de água, ganho de sólidos e atividade de água. A temperatura foi a variável que mais influenciou na perda de água e ganho de sólidos, seguida da concentração de sacarose da solução. A geometria de placa foi a que mais facilitou a perda de água no processo de desidratação osmótica tanto para a banana quanto para o mamão. O Modelo de Peleg e Azuara ajustaram-se bem os dados experimentais, sendo que os dados de equilibrio de perda de água que mais se aproximaram dos dados experimentais foram os calculado pelo Modelo de Azuara. Pela análise de imagens obtidas através da microscopia eletrônica de varredura foi possível verificar que as células da banana apresentam-se de forma alongada com presença de grânulos de amido e tanino, enquanto que as células do mamão apresentam-se forma oval. A geometria da amostra mostrou ser a variável que mais influenciou nas modificações ocorridas durante o processo de desidratação osmótica de ambas frutas, seguida da temperatura.
Abstract: In this work was studied mass transfer in banana (Musa cavendish) and papaya (Carica papaya L.) in osmotic dehydration process. It was analyzed the influence of geometry and cells structures to verify the best performance in mass transfer. Osmotic dehydration was carried on with constant agitation of 80 rpm and analyzed through a factorial experimental design 24-1with 3 repetitions of central point for each geometry. Analized variables were temperature (30, 45 and 60°C), sucrose concentration (3,5; 4,5 and 5,5 M), lactic acid concentration (O; 0,05 and O,lM) and sample geometry (fIat plate and cube). Analyzed responses were water 1055,solid gain and water activity. Water loss and solid gain were influenced more by temperature and after by sucrose concentration. In osmotic dehydration process, fIat plate geometry facilitated water loss in both banana and papaya. Peleg and Azuara's models fitted well to experimental data, but equilibrium data were better approached when they were calculated by Azuara's model. Analyzing obtained images through electronic microscopy scanning it was possible to verify that banana cells presented elongated shape with starch granules and tanine, while papaya cells presented egg-shaped. The variable that caused more influence in occurred changes during osmotic dehydration was sample geometry and after the temperature.
Mestrado
Mestre em Engenharia de Alimentos
Moura, Camila Alexandrino. "Aplicação de formulação baseada no método dos elementos finitos posicional na análise bidimensional elástica de compósitos particulados." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-27052015-172626/.
Full textThe use of composite materials has become an important alternative in many applications in different areas of engineering, because their constituents can add mechanical, thermal and acoustic properties to the composite, ensuring efficiency and low cost. Thus, it is necessary a better understanding of the mechanical behavior of these materials, mainly regarding displacement, stress and strain fields. This study aims to analyze, in macroscopic scale, two-dimensional elastic structures made of particulate composite materials, using formulation developed in the context of the Grupo de Mecânica Computacional (GMEC), of Departamento de Engenharia de Estruturas (SET), of Escola de Engenharia de São Carlos (EESC), of Universidade de São Paulo (USP). The formulation is based on the Positional Finite Element Method and was developed in mesoscopic level, considering the matrix-particles interaction and neglecting the interface, by means of kinematic relations used to ensure adherence of the particles to the matrix without introducing new degrees of freedom in the problem. The formulation considers isotropic material and geometric non-linear behavior of the composite phases. The application of the formulation was proposed in this work in order to evaluate the influence of geometry, size, volume fraction, distribution and mechanical properties of the particles adopted in the global behavior of the structure in macroscopic level. Numerical examples were developed and presented in order to compare the numerical results of the analysis with results obtained in experimental studies found in the literature, as well as results of mathematical models and numerical models using finite element method and the asymptotic homogenization technique.
Zabot, Giovani Leone 1988. "Obtaining bioactive compounds from clove and rosemary using supercritical technology: influence of the bed geometry, process intensification and cost of manufacturing of extracts = Obtenção de compostos bioativos de cravo-da-índia e alecrim utilizando tecnologia supercrítica: influência da geometria do leito, intensificação de processos de extração e custo de manufatura dos extratos." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/254901.
Full textTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: Substâncias naturais extraídas de plantas têm propriedades funcionais que as tornam preferíveis em relação às substâncias sintéticas, havendo grande interesse para aplicação farmacológica e na elaboração de bioprodutos. Técnicas de extração, como a que utiliza fluidos supercríticos, vêm se destacando por proporcionarem a obtenção seletiva de compostos bioativos com elevada qualidade. No campo da tecnologia supercrítica, pesquisas são desenvolvidas para aumentar o rendimento de extração através da alteração de condições de processo, como pressão e temperatura. No entanto, há a necessidade de discriminar mais a influência tecno-econômica de outras variáveis, como a geometria do leito de extração. Em vista disso, realizou-se a avaliação técnica da extração com CO2 supercrítico de compostos bioativos de cravo-da-índia e alecrim em uma unidade de extração laboratorial constituída por dois extratores de 1 L com diferentes razões de altura do leito (HB) pelo diâmetro (DB), sendo para o extrator 1 (E-1) a razão de 7,1 e para o extrator 2 (E-2) a razão de 2,7. Dois critérios utilizados para mudança de geometria e aumento de escala foram aplicados, consistindo em: (1) manutenção da velocidade intersticial do solvente igual em ambas as geometrias; e (2) manutenção da razão de massa de solvente por massa de matéria-prima (S/F) igual em ambas as geometrias para um determinado tempo de processo. De acordo com os resultados cinéticos de rendimento de extrato e composição química, o critério (1) não se mostrou indicado para ser aplicado em processos de extração com fluidos supercríticos (SFE) de compostos de cravo-da-índia. O critério (2) mostrou-se apropriado para a obtenção de óleo volátil de cravo-da-índia, pois houve igualdade nos perfis das curvas de extração em E-1 e E-2, avaliados em termos de parâmetros cinéticos como taxa de transferência de massa, duração dos períodos de taxa constante de extração (CER) e taxa decrescente de extração (FER), rendimento de extrato e razão mássica de soluto no solvente. No entanto, o critério (2) não se mostrou adequado para a obtenção de compostos bioativos de alecrim, sendo que o leito de extração E-2 proporcionou rendimentos até 86 % maiores em relação ao E-1, sendo a diferença mais notória no final do período FER. Houve diferença também no custo de manufatura (COM) dos extratos de alecrim simulado pelo SuperPro Designer 8.5®, sendo 23 % menor em E-2 do que em E-1 para uma planta industrial com 2 extratores de 100 L. Com relação ao alecrim, terpenoides majoritários como 1,8-cineol e cânfora foram extraídos com CO2 supercrítico. No entanto, alguns compostos fenólicos foram extraídos em pequena quantidade (ácido carnósico) ou nem foram extraídos via SFE (ácido rosmarínico). Logo, o conceito de intensificação de processos foi utilizado para facilitar a extração das duas frações presentes em alecrim. O processo consistiu em extrair inicialmente a fração rica em terpenoides com CO2 supercrítico (SFE-CO2) e logo após, no mesmo equipamento e sem desempacotar o leito, a fração rica em terpenos fenólicos foi extraída com água líquida pressurizada (PWE). Com isso, aproximadamente 2,5 % (m/m, base seca) de óleo volátil contendo terpenoides e 18,6 % (m/m, base seca) de extrato não-volátil contendo terpenos fenólicos foram obtidos em frações separadas. Um método analítico para quantificação de terpenos fenólicos por cromatografia líquida de alta eficiência foi desenvolvido e validado, com tempo total de análise de apenas 10 min. O custo operacional anual de uma planta produtiva instalada no Brasil com 2 extratores de 100 L foi simulado para os processos SFE-CO2 + PWE para obtenção de compostos de alecrim. O aproveitamento maior da matriz vegetal para a obtenção diversificada de compostos bioativos permitiu a redução em 28 % dos custos anuais de produção em relação ao processo SFE-CO2
Abstract: Natural substances extracted from plants present functional properties which are preferable against the synthetic ones, being useful in formulating bioproducts and in the pharmaceutical area. Novel extraction techniques, as the use of supercritical fluids, are acquiring notoriety by providing the selective extraction of bioactive compounds with high quality. In the supercritical technology field, researches are performed to increase the extraction yield by changing process conditions (i.e., pressure, temperature). However, there is a need for further techno-economic discriminations about the influence of other variables, as the bed geometry. Thus, we performed the evaluation of the supercritical CO2 extraction of clove and rosemary bioactive compounds using a laboratory equipment containing two extractors of 1 L with different height (HB) to bed diameter (DB) ratios. Bed 1 (E-1) and 2 (E-2) present HB/DB ratios of 7.1 and 2.7, respectively. Two criteria used for geometry shift and scale up were applied: (1) maintaining the solvent interstitial velocity equal in both bed geometries; and (2) maintaining the solvent mass to feed mass (S/F) ratio equal in both bed geometries for a fixed processing time. According to the kinetic results of extraction yields and chemical composition, the criterion (1) is not indicated for supercritical fluid extraction (SFE) of rosemary compounds. Criterion (2) is suitable for obtaining clove extract, because the extraction curves profiles were similar in E-1 and E-2. We evaluated the extraction curves in relationship to kinetic parameters as mass transfer rate, duration of constant extraction rate (CER) and falling extraction rate (FER) periods, extraction yield and mass ratio of solute in the fluid phase. However, criterion (2) is inappropriate for obtaining rosemary bioactive compounds. E-2 provided extraction yields up to 86% higher than E-1. The difference was more pronounced in the end of FER period. We observed differences on the cost of manufacturing (COM) of rosemary extracts simulated by SuperPro Designer 8.5®. COM¿s were 23% lower in E-2 than in E-1 for an industrial plant of 2 extractors of 100 L. With respect to rosemary, major terpenoids as 1,8-cineole and camphor were extracted with supercritical CO2, while some phenolic compounds were low (carnosic acid) or no extracted (rosmarinic acid) using SFE. Thus, process intensification concept was used for becoming possible the extraction of two fractions of bioactive compounds found in rosemary. The procedure comprised the initial extraction of the terpenoids-rich fraction with supercritical CO2 (SFE-CO2) and, thereafter, in the same equipment without unloading the bed, performing the extraction of the polyphenols-rich fraction with pressurized water (PWE). Approximately 2.5 wt.% (dry basis) of volatile oil containing terpenoids and 18.6 wt.% (dry basis) of non-volatile extract containing phenolic terpenes were obtained in separated fractions. We developed and validated an analytical method for quantifying phenolic terpenes by high performance liquid chromatography, presenting a total time of analysis of 10 min. Also, we simulated the annual operating cost of a plant installed in Brazil containing 2 vessels of 100 L applying SFE-CO2 + PWE processes for obtaining rosemary compounds. The higher use of the vegetal matrix for diversifying the extraction of bioactive compounds enabled 28% reduction in the annual production costs whether compared to SFE-CO2 process alone
Doutorado
Engenharia de Alimentos
Doutor em Engenharia de Alimentos
Yu, Chi-Heng, and 余其衡. "Influences of the geometrical and material parameters on the static characteristics of metallic and polymer aerostatic thrust bearings." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/79354021167300607231.
Full text國立雲林科技大學
機械工程系
103
A flexible bearing surface is combined with the concept of polymer restrictor to enhance the load capacity of aerostatic bearing in this thesis: Firstly a flexible disk, which is circularly supported near its rim, is adopted as the bearing component so that it can create a concave geometry and keep the air pressure to increase the load capacity. On the other hand, a polymer restrictor with capillary is set in the central outlet of air. The inner diameter of the capillary can expand with respect to the increase in load for compensating the air flux. Finally, the whole bearing is made of polymer body covered with metallic membrane. The polymer body can be fabricated conveniently by injection or molding and generates a damping effect under dynamic forces; while the metallic membrane possesses the ready-to-use roughness and prevents the polymer bulk from wear in case of over-thin air gap. The research proceeds from understanding the influences of the geometries, metallic materials and the supporting position on the characteristics of bearing. Then change the metals into polymer, which is combined with metallic membrane, and carry out a series of numerical simulations. Lastly use the Taguchi method to optimize the key factors that affect the load capacity and static stiffness. The experiments show that the circularly supported aerostatic bearing with polymer restrictor can tremendously improve the load ability. A thinner disk together with circular support at the position of approximately 5/6 of the disk radius can generate better results. The numerical analysis indicates that the Young’s modulus of the membrane has great impact on the bearing performance. The bearing with PU body and stainless steel membrane exhibits both the greatest loading capability and stiffness. Taking the bearings of radius 30 mm as examples, at elevation 9.5µm the stiffness soars from 16 N/µm of typical bearing to 350 N/µm under supply pressure 5 bar; meanwhile the load capacity also enhances from 346 N to 704N.
Chia, Hsu, and 徐嘉. "Geometrical Effects on the Fiber Micro-structure Variations and the Influences on the Warpage Behavior in Long Fiber Reinforced Thermoplastics (FRT) Injection Molding Product Development." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/7x4pcu.
Full text淡江大學
化學工程與材料工程學系碩士班
106
Due to its great potential and capability, the fiber reinforced thermoplastics (FRT) material and technology have been applied into industry recently. However, due to the microstructures of fiber inside plastic matrix are very complex, they are not easy to be visualized. The connection from microstructures to the final shrinkage/warpage is far from our understanding. In this study, we have performed a benchmark with three standard specimens based on ASTM D638 where those specimens have different gate designs. Due to the geometrical effect, the warpage behaviors are quite different for those three specimens. Although we expect long fiber reinforced to enhance strength, it causes one specimen warped downward and bended inward, another warped upward, and the other slightly upward at the same time. The difference might be due to the interaction of the entrance effect of molten plastic with fiber content to cause high asymmetrical fiber orientation distribution (FOD). We further studied that the asymmetrical FOD is introduced by the entrance effect from the sprue entrance of the part to the gate of each standard specimen. This entrance effect will cause the variation of FOD and further influence the fiber distribution and the bundle phenomena. Moreover, the experimental study is also performed to validate the simulation results. From short shot testing to the warpage and bending measurement for each individual model, overall, the tendency for both numerical simulation and experimental results is in a reasonable agreement. However, some deviation still existed which needs for further study. Furthermore, in the fiber length effect study experimentally, the longer fiber reinforced the less warpage. Also, the elongation and strength of injected parts can be enhanced significantly as fiber length increased. For example, from pure PP to FRP with 25 mm fiber inside, the strength can be increased from 20 N/mm2 to 140 N/mm2 .
HE, YAO-DONG, and 何耀東. "The influence of plane geometrical configuration of structure on the R-curve." Thesis, 1986. http://ndltd.ncl.edu.tw/handle/32286887828105145669.
Full textLi, Ming-Chou, and 李明州. "Volute Geometric Influence on the Performance of a low." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/69087874194306250047.
Full text國立屏東科技大學
機械工程系所
96
The purpose of this research is to investigate the pump performance by using different sectional volute shape such that a design principle can be followed. The pump type discussed in this research is restricted to low specific speed only. According to the Chinese National Standard (CNS) ‘s Small Size Volute Pump Regulation[3], the pump impeller diameter is assigned to 400 mm, and its operation condition (flow rate, speed, head) is in the low specific speed range, approximately 200. Input these operation information into Chiang’s pump design code CPD.for [2], the pump’s 3-D geometry can be acquired, then the 3-D model’s mesh can be constructed by using Gambit, and detailed flowfield data can be derived by using the flow solver Fluent. Observations on the flowfield concludes the reasons of how the flow energy losses occur. Analysis on the suitable operational range, efficiency, average efficiency in the operational range, the results shows the 60° fan type volute gives the best overall performance.
"Subsolador : a influencia de parametros geometricos na distribuição das forças." Tese, Biblioteca Digital da Unicamp, 1989. http://libdigi.unicamp.br/document/?code=vtls000045427.
Full textHOU, WONG TECK, and 王荻皓. "Influences of Different Geometric Parameters on Rudder Characteristics for High-Speed Crafts." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/04628585374665116098.
Full text國立臺灣大學
造船及海洋工程學研究所
89
The turbulent flow around rudders is computed and analyzed by solving the Reynolds-averaged Navier-Stokes equations to investigate the hydrodynamic performance, such as lift, drag, stock moment and stall angle, of several rudders used on high-speed craft with various geometric parameters. A second order finite volume method with multi-block structured grid system is applied to discretize the equation and space respectively. The standard k-ε turbulent model is employed to take account of the turbulent effect. Good agreements are obtained between the computational and experimental results. The present studies focus on the performance analysis of several practical rudders with NACA 00XX, NACA 16, NACA 66, WedgeXX, EllipseXX and RectangleXX profiles (see Appendix A and B) at Reynolds number Re of 106. Three basic non-dimensional coefficients: lift CL(α), drag CD(α) and moment CM(α), being functions of the angle of attack α of the rudder are evaluated to investigate the influences of Reynolds number, profile shape, aspect ratio, taper ratio and profile thickness, on the performance of high-speed craft rudders. Also, the position of the rudder shaft center was varied along the nose-tail line, in order to find out the stock location of minimum moment for each rudder. Furthermore, the pressure coefficient Cp and the shear stress distribution on each rudder surface are presented. In general, the NACA 00XX rudders show a better performance compared to other calculated rudders in this work.
Liu, Mei-Ting, and 劉美廷. "Influences of colour, size and smoothness on visual conspicuity of basic geometric shapes." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/3qsjj9.
Full text國立臺灣科技大學
色彩與照明科技研究所
104
In this colourful world which is information overload, how can we efficiently get the right information we need? Efficiently visual searching is important. More conspicuous the target is, more attention the target can attract. The relationship between conspicuity and colour attributes, size and smoothness was investigated in this study. Two experiments were conducted in this study. The first experiment was psychological quantification of size and smoothness of rounded triangles, with various round corner ratio, i.e. the diameter of the round corner divided by the height of the shape. The second experiment was conspicuity experiment. The first experiment used psychophysical methods to develop models of psychological quantification of size and smoothness. The models were used to set up the test shapes for use in the second experiment. The visual conspicuity was defined in this study as the reciprocal of reaction time. Observers were asked to find the target from twenty-four shapes as soon as possible. The experiment had four parts : (1) the test of reaction time for mouse movement, (2) the influence of characteristics of the shape on conspicuity, (3) the influence of colours on conspicuity, (4) developing and testing the conspicuity model. The model of mouse movement was derived in the first part of the experiment to exclude the influence of the position of the target. The conspicuity models based on the impact of size, smoothness and colour were developed in the second and the third parts. A final version of the conspicuity model was derived on the basis of the three models for size, smoothness and colour, and was tested in the fourth part of the experiment with satisfactory predictive performance.
林宏興. "Influence of magnetization switching with exchange coupling effect in geometric asymmetry disk." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/98321269816657269377.
Full text國立彰化師範大學
物理學系
97
Abstract The geometric asymmetry disk can control the chirality on disk. There are many study about patterned ferromagnetic disk. The research about geometric asymmetry disk in antiferromagnetic/ferromagnetic are not vary popular. The article in this study is compare antiferromagnetic/ferromagnetic magnetization switching with the ferromagnetic in geometric asymmetry disk. The NiFe and NiFe/IrMn structure are fabricated by sputtering system. Determining the geometric asymmetry pattern by e-beam lithography and etching by ICP-RIE. The excised angles are 15, 30, 60, and 90 degree. The diameter are 500 and 800nm. The M-H loop ware measured by magnetic magneto-optical Kerr effect. In 500 and 800 nm NiFe/IrMn disk, the nucleation field (Hn) are deceasing when excised angle increase. The annihilation field (Han) are smaller than NiFe one and have similar tendency. In NiFe/IrMn structure 800-nm-diameter 90-degree-excised angle, the magnetization switching can find vortex nucleation field easily. The exchange bias are not larger to observe in 500 and 800-nm-diameter NiFe/IrMn structure. But, M-H loop has clear shift in 2μm disk array.
CHI, HSU HAN, and 徐漢圻. "Study on Influences of Geometric Parameters of a Bulbous Bow on Ship Wave Resistance." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/80284465267241567308.
Full textChen, Yu-Min, and 陳俞閔. "Influences of Salt Valence and Geometric Shape of a Nanochannel on Its Rectification Behavior." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/mn45tg.
Full text國立臺灣大學
化學工程學研究所
106
The overlapping of electric double layer in a nano-scaled system is usually significant, rendering it having profound and interesting electrokinetic phenomena, such as ion concentration polarization (ICP) and ion current rectification (ICR), and thus fabrication of nanodevices becomes a trend of nanotechnology. In Chapter 1, by taking account of various electrolyte solution LaCl3、CaCl2、KCl、KNO3, and K2SO4, a thorough numerical simulation is conducted to illustrate the influence of asymmetry of various ionic valence ratio on the ICR behavior in a conical nanochannel. We show that the electrokinetic phenomena depend highly on ionic strength and ion diffusivity. The qualitative behavior of the ion current rectification of a positively charged conical nanochannel is similar to that of a negatively charged one.In Chapter 2, we consider a bioinspired cigar-shaped nanochannel where its surface is pH-regulated, and has zwitterionic groups. The influences of the solution pH, the bulk concentration, the base opening radii, and the nanochannel shape on the associated ICR behavior and ionic selectivity are examined, focusing on discussing the underlying mechanisms in detail. We show that the best nanochannel performance can be achieved by adjusting the base orifice radii and surface curvature appropriately. In addition to proposing underlying mechanisms for the phenomena observed, the results gathered in this study also provide necessary information for designing relevant devices.