• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 12
  • 10
  • 5
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 32
  • 10
  • 10
  • 9
  • 7
  • 6
  • 6
  • 6
  • 5
  • 5
  • 5
  • 5
  • 4
  • 4
  • 4
  • 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.
11

Par?metros citogen?ticos de esp?cies comerciais de carangidae (perciformes), com vistas a sua empregabilidade na conserva??o biol?gica e piscicultura marinha

Jacobina, Uedson Pereira 28 September 2012 (has links)
Made available in DSpace on 2014-12-17T14:05:21Z (GMT). No. of bitstreams: 1 UedsonPJ_TESE.pdf: 4652732 bytes, checksum: 9faad092c54691708dbf548da7b7add7 (MD5) Previous issue date: 2012-09-28 / Worldwide, families Carangidae and Rachycentridae represent one of the groups most important commercial fish, used for food, and great potential for marine aquaculture. However, the genetic bases that can underpin the future cultivation of these species, cytogenetic between these aspects are very weak. The chromosomal patterns have provided basic data for the exploration of biotechnological processes aimed at handling chromosomal genetic improvement, such as induction of polyploidy, androgenesis and ginogenesis, as well as obtaining monosex stocks and interspecific hybridizations. This paper presents a comprehensive cytogenetic survey in 10 species, seven of the family Carangidae and the monotypic family Rachycentridae. Classical cytogenetic analysis and in situ mapping of multigene sequences were employed, and additionally for the genus Selene and morphotypes of Caranx lugubris, comparisons were made using geometric morphometrics. In general, conservative species exhibit a marked chromosome number (2n=48). Although present in large part, different karyotypic form, retain many characteristics typical of chromosomal Order Perciformes, the high number of elements monobrachyal, Ag-NORs/18S rDNA sites and heterochromatin simply reduced, preferably centromeric. The main mechanisms involved in karyotypic diversification are the pericentric inversions, with secondary action of centric fusions. In addition to physical mapping and chromosome detail for the species are presented and discussed patterns of intra-and interspecific diversity, cytotaxonomic markers. This data set provides a better understanding of these patterns caryoevolutyonary groups and conditions for the development of protocols based on Biotechnology for chromosomal manipulation Atlantic these species / Entre os peixes marinhos, as fam?lias Carangidae e Rachycentridae se apresentam como grupos de grande import?ncia comercial pela pesca e potencial para piscicultura marinha. Entretanto, bases gen?ticas que possam alicer?ar o futuro cultivo destas esp?cies, sobretudo seus aspectos citogen?ticos s?o incipientes. Os padr?es cromoss?micos t?m fornecido dados b?sicos para a prospec??o de processos biotecnol?gicos de manipula??o cromoss?mica voltados ao melhoramento gen?tico, como a indu??o a poliploidia, ginog?nese e androg?nese, assim como obten??o de estoques monossexo e hibridiza??es interespec?ficas. Neste trabalho ? apresentado um amplo levantamento citogen?tico em 10 esp?cies, sendo sete da fam?lia Carangidae e de Rachycentron canadum, esp?cie monot?pica da fam?lia Rachycentridae. A caracteriza??o citogen?tica cl?ssica e mapeamento in situ de sequ?ncias multig?nicas foram empregadas. Adicionalmente em esp?cies do g?nero Selene e em morf?tipos de Caranx lugubris foram realizadas compara??es atrav?s de morfometria geom?trica. Em geral, as esp?cies exibiram um marcante conservadorismo cromoss?mico num?rico (2n=48). Apesar de apresentar, em grande parte, f?rmulas cariot?picas diferenciadas, conservam diversas caracter?sticas cromoss?micas t?picas da Ordem Perciformes, como elevado n?mero de elementos monobraquiais, s?tios Ag-RONs/ DNAr 18S simples e heterocromatina reduzida, preferencialmente centrom?rica. Os principais mecanismos envolvidos na diversifica??o cariot?pica s?o as invers?es peric?ntricas, com a??o secund?ria de fus?es c?ntricas. Al?m do mapeamento f?sico e detalhamento cromoss?mico para as esp?cies s?o apresentados e discutidos padr?es de variabilidade intra e diversifica??o interespec?ficas, com identifica??o de marcadores citotaxon?micos. Este conjunto dos dados propicia um melhor conhecimento dos padr?es carioevolutivos destes grupos e condi??es para o desenvolvimento de protocolos biotecnol?gicos baseados na manipula??o cromoss?mica para estas esp?cies Atl?nticas
12

An?lise da reativa??o de falhas normais atrav?s da modelagem f?sica com o uso do particle image velocimetry

Sousa, Lu?s Kennedy Andrade de 02 September 2016 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-02-20T22:47:58Z No. of bitstreams: 1 LuisKennedyAndradeDeSousa_DISSERT.pdf: 5262819 bytes, checksum: 804c2a834cbc99f7b44d5b9292ca41db (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-02-24T21:52:22Z (GMT) No. of bitstreams: 1 LuisKennedyAndradeDeSousa_DISSERT.pdf: 5262819 bytes, checksum: 804c2a834cbc99f7b44d5b9292ca41db (MD5) / Made available in DSpace on 2017-02-24T21:52:22Z (GMT). No. of bitstreams: 1 LuisKennedyAndradeDeSousa_DISSERT.pdf: 5262819 bytes, checksum: 804c2a834cbc99f7b44d5b9292ca41db (MD5) Previous issue date: 2016-09-02 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A modelagem anal?gica, desde o s?culo XIX, vem sendo usada para simular estruturas geol?gicas com o objetivo de entender os mecanismos que controlam sua geometria e cinem?tica. O uso desta ferramenta na ind?stria do petr?leo, para ajudar a interpreta??es s?smicas e, principalmente, para procurar armadilhas estruturais, contribu?ram para difundir o uso desta ferramenta na literatura. Estudos envolvendo a modelagem anal?gica de invers?o de bacias s?o desenvolvidos para melhorar o entendimento dos fatores que influenciam na reativa??o das estruturas pr?-existentes, bem como sua geometria. Neste trabalho, procurou-se analisar a constru??o da arquitetura estrutural de um modelo de sistemas de falhas que sofre invers?o positiva, e analisar a rela??o entre a gera??o de novas falhas e a reativa??o das falhas normais pr?- existentes, durante um evento contracional. Adicionalmente, efetuou-se a an?lise do comportamento e distribui??o do strain ao longo do processo deformacional a partir de imagens obtidas e processadas pelo sistema Particle Image Velocimetry (PIV). Foram estudados duas s?ries de experimentos: i) S?rie I: Analisou-se a gera??o de falhas associadas a gera??o de uma falha l?strica principal e sua reativa??o durante a invers?o cinem?tica. Nesta s?rie, dois tipos de modelos foram realizados: um com a falha l?strica, ortogonal a dire??o de tra??o e compress?o (S?rie IA), e no outro a falha l?strica foi obl?qua (??? = 80?) (S?rie IB). A configura??o estrutural final da invers?o positiva mostrou a reativa??o da falha principal, com a reativa??o de algumas falhas normais que delimitam a estrutura grabenforme. Empurr?es e retroempurr?es s?o desenvolvidos e se enra?zam a partir da por??o basal da falha l?strica, ou se desenvolveram na parte superior do pacote sedimentar, propagando-se em dire??o ? base da estrutura grabenforme; ii) S?rie II: Analisou-se a gera??o de falhas associadas ? forma??o de uma falha mestra planar, ortogonal ? dire??o de tra??o/compress?o. Nestes experimentos procurou-se tamb?m observar o papel da reologia na predisposi??o de falhas normais serem reativadas. Para esta s?rie de experimentos, tr?s tipos de experimentos foram realizados com sequ?ncias pr?-tect?nicas constitu?das por diferentes tipos de material: apenas areia (s?rie IIA); areia e gesso (s?rie IIB); e areia e argila (s?rie IIC). Nos experimentos da s?rie II, a arquitetura estrutural final mostra que falhas normais foram completamente ou parcialmente reativadas, al?m do desenvolvimento de empurr?es e retroempurr?es que seccionam a por??o basal da estrutura grabenforme. Os dados obtidos com o sistema PIV, mostraram que durante o v in?cio da compress?o, a deforma??o foi absorvida primeiramente pela compacta??o do material granular, e que ap?s este processo, ocorre a reativa??o e cria??o de novas falhas, e que determinadas falhas alternam em intervalos ativos e inativos. / Analog modeling has been used since the XIX century to simulate geological structures in order to understand the mechanisms that control their geometry and kinematics. The use of this tool in the oil industry, to help seismic interpretations (mainly searching for structural traps), helped to spread its use in the literature. Studies involving basin inversion are developed to improve understanding factors that influence the reactivation of pre-existing structures as well as their geometry. In this work, we analyze the construction of the structural architecture of a fault system that underwent positive inversion, and analyzed the relationship between the generation of new faults and reactivation of pre-existing normal faults during a contraction event. In addition, the behavior and distribution of strain along the deformation process were performed based on images obtained and processed by Particle Image Velocimetry (PIV) system. Two series of experiments were developed: i) Series I: we analyzed the generation of fault sets associated with a main listric fault and their reactivation during an inversion event. Two types of models were performed: one with listric fault, orthogonal to the direction of tension and compression (series IA), while in the other the l?strica fault was oblique (obliquity = 80) (series IB). The final structural configuration after inversion showed major fault and some of the normal faults (delimiting the grabenform structure) reactivated. Thrust and backthrust were developed from the basal portion of listric fault, or in the upper part of the model, propagating towards the base of grabenform structure; ii) Series II: we analyzed the generation of faults associated with the formation of a planar master fault, orthogonal to the direction of both tension and compression. In these experiments, the role of rheology during normal faults reactivation was analyzed. Three types of experiments were done varying the materials of the pre-tectonic sequences: sand only (series IIA); sand and gypsum ponder (series IIB); and sand and clay (series IIC). These experiments displayed the final architecture with normal faults completely or partially reactivated, and the developed thrusts and backthrust sliced up the basal portion of the grabenform structure. PIV data showed that during the first stages of compression, deformation was absorbed mainly by rearrangement of the granular material (compactation) and only after this process fault reactivation (or new fault) occurs. During deformation, some faults alternated intervals of activity and inactivity.
13

Processamento e caracteriza??o da Blenda poli(metacrilato de metila) (PMMA) com part?culas elastom?ricas e policarbonato (PC)

Macedo, Thatiana Cristina Pereira de 13 February 2017 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-06-02T19:15:14Z No. of bitstreams: 1 ThatianaCristinaPereiraDeMacedo_DISSERT.pdf: 3768297 bytes, checksum: d9955850273479736f103ea6caab98f3 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-06-05T19:38:31Z (GMT) No. of bitstreams: 1 ThatianaCristinaPereiraDeMacedo_DISSERT.pdf: 3768297 bytes, checksum: d9955850273479736f103ea6caab98f3 (MD5) / Made available in DSpace on 2017-06-05T19:38:31Z (GMT). No. of bitstreams: 1 ThatianaCristinaPereiraDeMacedo_DISSERT.pdf: 3768297 bytes, checksum: d9955850273479736f103ea6caab98f3 (MD5) Previous issue date: 2017-02-13 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / O presente trabalho teve como objetivo realizar um estudo do comportamento reol?gico, mec?nico e microestrutural da blenda poli(metacrilato de metila)/policarbonato (PMMA/PC), utilizando um PMMA com part?culas elastom?ricas at? a invers?o de fase. A prepara??o da blenda PMMA/PC foi feita em extrusora rosca simples e rosca dupla co-rotacional, com posterior moldagem por inje??o. As mudan?as nas caracter?sticas f?sicas e qu?micas do policarbonato foram analisadas por viscosimetria e por espectroscopia de absor??o no infravermelho por transformada de Fourier (FTIR), antes e ap?s o processamento. As caracteriza??es mec?nicas foram realizadas por ensaio de tra??o uniaxial e impacto Izod. Os ensaios reol?gicos foram feitos por medidas de ?ndice de fluidez (MFI) e reometria capilar. Para a an?lise microestrutural da blenda polim?rica foram utilizados microscopia de for?a at?mica (AFM) e microscopia eletr?nica de varredura (MEV). A temperatura de in?cio de decomposi??o t?rmica foi determinada por an?lise termogravim?trica (TG). Os resultados do MFI nas condi??es de processamento indicaram maior fluidez do policarbonato e que, entre todas as composi??es estudadas, a maior parte delas apresentou maior valor de MFI para os materiais processados em extrusora rosca dupla. Por reometria capilar dos materiais sem processamento, observou-se menor varia??o da viscosidade do PC em fun??o do aumento da taxa de cisalhamento. Por TG, foi verificada maior temperatura de in?cio de degrada??o para o PC, mas o processamento alterou mais a estabilidade t?rmica desse pol?mero do que para o poli(metacrilato de metila). As medidas de viscosidade intr?nseca do policarbonato indicaram uma poss?vel degrada??o por cis?o de cadeias, ap?s o processamento, devido a diminui??o da massa molar do material. Por FTIR, n?o foram identificadas bandas distintas para o PC antes e ap?s o processamento. A caracteriza??o mec?nica por tra??o uniaxial revelou maior resist?ncia m?xima ? tra??o, maior m?dulo de elasticidade e maior alongamento na ruptura para o policarbonato e que a compatibilidade da blenda PMMA/PC variou com a concentra??o de PC, sendo observadas algumas composi??es que apesentaram sinergismo nas propriedades. Por resist?ncia ao impacto Izod, foi constatada a elevada resist?ncia ao impacto do PC, quando comparado ao PMMA, mas a adi??o de 20% em massa de PC na matriz de PMMA elevou de forma significativa a resist?ncia ao impacto da blenda PMMA/PC. Pela an?lise morfol?gica por AFM, foi poss?vel visualizar a presen?a de part?culas elastom?ricas esf?ricas com tamanho m?dio de cerca de 182 ? 20 nm no PMMA, distribu?das de forma uniforme ao longo de sua microestrutura; enquanto o PC apresentou apenas uma fase homog?nea. Para a blenda PMMA/PC, verificou-se a presen?a de duas fases bem definidas ao longo de todas as composi??es, e houveram ind?cios de morfologia com caracter?sticas de co-continuidade para as composi??es entre a 70/30 e 50/50, tanto para os materiais processados em extrusora rosca simples quanto em rosca dupla. No que diz respeito as propriedades mec?nicas da blenda PMMA/PC, as composi??es com maior percentual de PMMA foram as que apresentaram melhores resultados de alongamento na ruptura e resist?ncia na ruptura, com propriedades intermedi?rias de resist?ncia ao impacto Izod. Na invers?o de fases, por sua vez, os resultados seguiram as caracter?sticas do policarbonato, n?o havendo ganhos significativos de propriedades. / The aim of this work was to study the rheological, mechanical and microstructural behavior of poly (methyl methacrylate)/polycarbonate (PMMA/PC) blends using a PMMA with elastomeric particles until phase inversion. The PMMA/PC blends were processed in single screw extruder and co-rotational twin screw extruder, with subsequent injection molding. The changes in the physical and chemical characteristics of the polycarbonate were analyzed by viscosimetry and by Fourier transform infrared spectroscopy (FTIR) before and after processing. The mechanical characterizations were performed by uniaxial tensile test and Izod impact. The rheological tests were done by melt flow index (MFI) and capillary rheometry. Microstructural analysis of the polymer blends was performed using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The thermal degradation temperature was determined by thermogravimetric analysis (TGA). The results of the MFI in the processing conditions indicated a higher flowability of the polycarbonate among all the studied compositions; most of them present higher value of MFI for the materials processed in twin screw extruder. In the capillary rheometry of the unprocessed materials a lower PC viscosity variation was observed as a function of the shear rate increase. TGA showed a higher degradation onset temperature for the PC, but the processing altered the thermal stability of that polymer more than for poly (methyl methacrylate). The intrinsic viscosity measurements of the polycarbonate indicated a possible degradation by chain scission after processing due to the decrease in the molar mass of the material. The FTIR did not identify distinct bands for the PC before and after the processing. The mechanical characterization by uniaxial tensile revealed higher tensile strength, higher modulus of elasticity and greater elongation at break for polycarbonate, and the compatibility of PMMA/PC blends varied with PC concentration, with some compositions that showed synergism in the properties. Izod impact strength showed a high PC impact strength when compared to PMMA, but the addition of 20 wt% of PC in the PMMA matrix significantly increased the impact strength of PMMA/PC blends. The morphological analysis by AFM visualized the presence of spherical elastomeric particles with an average size of about 182 ? 20 nm in the PMMA, evenly distributed along its microstructure, while the PC presented only one homogeneous phase. The PMMA/PC blend showed two well-defined phases throughout all the compositions, and showed evidence of morphology with co-continuity characteristics for the compositions between 70/30 and 50/50 wt%, both for the materials processed in single screw extruders as well as twin screw extruders. The compositions with the highest percentage of PMMA in the PMMA/PC blends were the ones with the best results of rupture strength and elongation at break, and the Izod impact resistance showed intermediate properties. The results in the phase inversion followed the characteristics of the polycarbonate, not showing significant gains of properties.
14

Stambråkets möjligheter att berika bråkundervisningen : En läromedelsanalys om en läromedelsseries möjligheter att utveckla en förståelse för stambråk i grundskolans årskurs 4-6.

Didrik Sjöbladh, Linda, Nordliden, Petter January 2021 (has links)
Denna läromedelsanalys syftar till att utifrån ett variationsteoretiskt perspektiv belysa vilka möjligheter en läromedelsserie i matematik erbjuder elever att utveckla en förståelse för stambråk. Studien utgår från sex kritiska aspekter av stambråk: areamodellen, linear measurement, inverse order relationship, stambråk som mängden av en helhet, partitioning och iterating. Utifrån ett variationsteoretiskt perspektiv med en deduktiv ansats har läromedlen analyserats genom en textanalys. Resultatet visar att samtliga kritiska aspekter av stambråk finns representerade i läromedlet. Samtidigt behandlas flertalet av dem i mindre utsträckning, vilket kan leda till en begränsad concept image av stambråk hos elever. Resultatet visar även att det vanligaste variationsmönstret i läromedlen är fusion, vilket innebär att elever behöver kunna urskilja flera kritiska aspekter av lärandeobjektet samtidigt. Detta försvårar möjligheten att tillägna sig förståelsen för stambråk. I resultatet framgår det också att areamodellen är den vanligast förekommande representationsformen i läromedelsserien. En konsekvens för undervisningen blir således att representations-former som bygger på linear measurement behöver få större plats inom ramen för den ordinarie undervisningen. Detta för att elever ska få en större förståelse för stambråk och en berikad concept image vilket i sin tur möjliggör förståelsen för mer avancerade matematiska principer. Sammanfattningsvis diskuteras att lärare behöver förhålla sig kritiskt till matematikläromedel samt vara medvetna om vilka möjligheter det erbjuder.
15

Rättvisa för division! : En litteraturstudie om hur elever utvecklar förståelsen för den inversa relationen mellan multiplikation och division / Justice for division! : A literature study about how pupils develop an understanding for the inverse relation between multiplication and division

Sparf, Joline, Simonsson Annas, Emilia January 2023 (has links)
Den inversa relationen mellan multiplikation och division innebär att räknesätten är varandras motsatser. Att använda den inversa relationen som metod innebär att man kan använda sig av multiplikation för att beräkna division men också vice versa. Förståelsen för denna relation har visat sig vara viktig för elevers talförståelse och är där med viktig att undervisa om.  Den här litteraturstudiens syfte är att sammanställa vad vetenskapliga studier belyser som betydelsefullt för elevers förståelse av den inversa relationen mellan multiplikation och division. Syftet uppfylls genom att besvara frågeställningen: Vad är betydelsefullt för att elever ska utveckla förståelse för den inversa relationen mellan multiplikation och division? Denna litteraturstudie baseras på tio systematiskt framtagna vetenskapliga tidskriftsartiklar som inhämtades via sökningar i databaserna ERIC och PsycInfo. Alla artiklar i studien är internationella och skrivna på engelska. Materialet analyserades med hjälp av inkluderings- och exkluderingskriterier samt en översiktsmall.  Resultatet visar att förståelsen för relationen mellan multiplikation och division är ett område som är bristfälligt för många elever. Detta kan ha en negativ påverkan på elevers kunskaper inom matematik och kan hämma att en djupare förståelse utvecklas. Denna litteraturstudie presenterar sex aspekter som är betydelsefulla i barns utveckling av förståelsen för den inversa relationen mellan multiplikation och division. Studien kan vara till hjälp för lärare i deras planering och utformning av undervisning kring multiplikation och division.
16

Mesures géodésiques et modélisation de la convergence oblique au travers de failles transformantes. Application au bord Nord du Plateau Tibétain et à la Californie du Sud / Geodetic measurements and modeling of oblique convergence across transform faults. Application to the Northern Tibetan Plateau and to Southern California

Daout, Simon 21 November 2016 (has links)
Je me focalise sur trois grands systèmes de failles transformantes obliques au Tibet et en Californie du Sud, et ce, afin de mieux comprendre et quantifier les relations entre les différentes structures qui les définissent. L'interférométrie radar à Synthèse d'Ouverture (InSAR) dispose du potentiel pour cartographier et localiser précisément la déformation sur des zones étendues et ainsi contraindre la géométrie des structures profondes. Cependant son utilisation en milieu naturel se trouve fortement entravée par la décorrelation due à la végétation, au relief, et aux cycles de gel et dégel, mais aussi par les délais troposphériques et les rampes orbitales résiduelles. J'ai développé des méthodes pour palier ces limitations. Au Tibet, j'ai ainsi traité les archives du satellite Envisat au niveau de deux zones de lacune sismique, à la bordure Nord du plateau, se présentant comme des zones intéressantes pour étudier le partitionnement de la convergence: le système de faille de Haiyuan au north-est Tibet et la faille sénestre de l'Altyn Tagh, au nord-ouest du plateau. Une attention spécifique sur les déformations liées au pergélisol m'a permis de (1) retrouver la continuité du signal sur de grandes zones, (2) de quantifier le comportement temporel des cycles de gel et dégel des sédiments recouvrant le pergélisol, (3) d'isoler les zones stables des sédiments se déformant. Je montre que les déformations saisonnières sont fortement dépendantes des unités géomorphologiques et que la fonte du pergélisol est plus important à faible qu'à haute altitude. J'analyse aussi le signal saisonnier au travers la marche topographique et je définie un proxy pour les incertitudes de la correction atmosphérique. J'observe un gradient de déformation au travers la faille de l'Altyn Tagh de l'ordre de 11-15 mm/an et un alignement claire de la déformation dans le Tarim, parallèle à la faille de l'Altyn Tagh, ainsi que des soulèvements de l'ordre de 1 mm/an associés à des chevauchements. Ce travail montre aussi un gradient de déformation associé à la terminaison ouest de la faille du Kunlun, re-définissant ainsi la géométrie des blocs tectoniques dans cette région. Parallèlement à cette acquisition de données, je développe des outils d'inversion basés sur des algorithmes de Monte Carlo afin d'explorer l'ensemble des géométries en accord avec les observations et d'estimer la compatibilité de la déformation actuelle avec des modèles tectoniques long-termes. Je montre ainsi une convergence uniforme de 8.5-11.5 mm/an et d'orientation N81-98E à travers le système de faille d'Haiyuan et quantifie son partitionnement le long des différentes structures. Par ailleurs, j'applique mon approche en Californie du Sud, au niveau du « Big Bend » de la faille de San Andreas où, en analogie avec des modèles structuraux géologiques, j'utilise des lois de conservations du mouvement pour contraindre la géométrie des chevauchements aveugles. Je montre la compatibilité du champs de déformation actuel avec un décollement grande échelle et quantifie une accumulation de contrainte de 2.5 mm/an le long de la structure majeure sous Los Angeles. / I focus on three major oblique transform faults in Tibet and in Southern California, in order to better measure and quantify the present-day strain accumulation on these structures. Interferometric synthetic Aperture Radar (InSAR) has the potential to map and localize precisely the deformation over wide areas and thus constrain the deep geometry of these structures. However, its application in natural environments in hindered by strong decorrelation of the radar phase due to vegetation, relief, and freeze and thaw cycles, but also due to variable tropospheric phase delays across topographic feature and long-wavelength residual orbital ramps. Here, I develop methodologies to circumvent these limitations and separate tectonic from other parasite signals. In Tibet, I process data from the Envisat satellite archives, at the boundary of the Tibetan plateau, in two seismic gaps, which appear interesting to study the partitioning of the convergence: the Haiyuan Fault system in northeastern Tibet and the left-lateral Altyn Tagh Fault, in northwestern Tibet. A specific focus on the permafrost related deformation signal allows us to: (1) correctly unwrap interferograms from north to south, (2) quantify the temporal behavior of the freeze/thaw cycles, and (3) isolate bedrock pixels that are not affected by the permafrost signal for further tectonic analysis. I show that the seasonal subsidence depends greatly on the geological land unit and that lower elevations are thawing faster than higher elevations. I analyze the atmospheric signal across the high plateau margin and estimate proxy for the uncertainty on atmospheric corrections. I observe a strike-slip deformation of around 11-15 mm/yr across the Altyn Tagh fault, a clear line of concentrated strike-slip deformation of around 3 mm/yr within the Tarim basin, trending parallel to the Altyn Tagh Fault trace, as well as thrust signal uplifting terraces at a rate of 1 mm/yr. This work also shows a strain accumulation around the west extension of the south trace of the Kunlun Fault, redefining the block boundaries in northwestern Tibet. In parallel this data acquisition, I develop Monte Carlo inversion tools in order to explore the various geometries in agreement with observations and estimate the compatibility of actual surface displacements with long-term slip partitioning models. I thus show a uniform convergence rate of 8.5-11.5 mm/yr with a N81-98E across the Haiyuan fault system and quantify the partitioning along the various structures. I also apply my approach in Southern California, across the « Big Bend » of the San Andreas Fault, where, in analogy with structural geological models, I use conservation of motion to help constraining the geometry and the kinematics of blind thrust faults. I show the compatibility of surface displacements with a large-scale décollement and quantify a loading rate of 2.5 mm/yr along the major thrust structure developing under Los Angeles.
17

Utiliza??o de sismos regionais para a determina??o de um modelo 1D de velocidades da onda P na Prov?ncia Borborema - NE do Brasil

Shihadeh, Hasan Lopes 08 September 2015 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-07-25T19:35:29Z No. of bitstreams: 1 HasanLopesShihadeh_DISSERT.pdf: 4749062 bytes, checksum: 5c56d7aad70a0d9ccc2eba27d546688b (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-07-28T23:45:09Z (GMT) No. of bitstreams: 1 HasanLopesShihadeh_DISSERT.pdf: 4749062 bytes, checksum: 5c56d7aad70a0d9ccc2eba27d546688b (MD5) / Made available in DSpace on 2016-07-28T23:45:09Z (GMT). No. of bitstreams: 1 HasanLopesShihadeh_DISSERT.pdf: 4749062 bytes, checksum: 5c56d7aad70a0d9ccc2eba27d546688b (MD5) Previous issue date: 2015-09-08 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Neste trabalho foi realizado um estudo para a obtenc?a?o de para?metros para um modelo regional de velocidades 1D va?lido para a Provi?ncia Borborema, NE do Brasil. Para tanto, foram utilizados eventos que ocorreram na mesma entre 2001 e 2013 com magnitude acima de 2.9 e que tiveram epicentros bem determinados por redes locais de estac?o?es ou back azimuth, quando os dados sa?o de boa qualidade. Foram escolhidos 7 eventos ocorridos nas principais a?reas si?smicas da Provi?ncia Borborema. Os eventos selecionados foram, ao todo, registrados em 74 estac?o?es das redes: RSISNE, INCT-ET, Mile?nio, Joa?o Ca?mara - RN, Sa?o Rafael - RN, Caruaru - PE, Sa?o Caetano - PE, Castanha?o - CE, Santana do Acarau - CE, Taipu - RN e Sobral - CE e a estac?a?o RCBR da rede IRIS/USGS - GSN. Para a determinac?a?o dos para?metros do modelo realizou-se a inversa?o do tempo de percurso atrave?s de um ajuste de retas aos tempos observados. A validac?a?o deste modelo se deu de modo independente atrave?s da comparac?a?o com outros modelos conhecidos (globais e regionais para o Brasil). O modelo final, nomeado MBB, apresenta um modelo crustal lateralmente homoge?neo composto por duas camadas com crosta superior de 11,45 km de espessura e uma crosta com espessura total de 33,90 km, sendo a base da segunda camada limitada pela descontinuidade de Moho. A velocidade da onda P na crosta superior foi estimada em 6,00 Km/s e na crosta inferior 6,64 Km/s. A velocidade da onda P no manto superior foi estimada em 8,21 Km/s com uma raza?o VP/VS de aproximadamente 1,740 ? 0,002. / In this work it was performed a study to obtain parameters for an 1D regional velocity model for the Borborema Province, NE Brazil. It was used earthquakes occurred between 2001 and 2013 with magnitude greater than 2.9 mb either from epicentres determined from local seismic networks or by back azimuth determination, when possible. We chose seven events which occurred in the main seismic areas in the Borborema Province. The selected events were recorded in up to 74 seismic stations from the following networks: RSISNE, INCT-ET, Jo?o C?mara ? RN, S?o Rafael ? RN, Caruaru - PE, S?o Caetano - PE, Castanh?o - CE, Santana do Acarau - CE, Taipu ? RN e Sobral ? CE, and the RCBR (IRIS/USGS?GSN). For the determination of the model parameters were inverted via a travel-time table and its fit. These model parameters were compared with other known model (global and regional) and have improved the epicentral determination. This final set of parameters model, we called MBB is laterally homogeneous with an upper crust at 11,45 km depth and total crustal thickness of 33,9 km. The P-wave velocity in the upper crust was estimated at 6.0 km/s and 6.64 km/s for it lower part. The P-wave velocity in the upper mantle we estimated at 8.21 km/s with an VP/VS ratio of approximately 1.74.
18

Construction of a Selective Compliance Articulated Robot Arm : And evaluation of its accuracy / Konstruktion av en utvalt eftergivlig robotarm : Och utvärdering av dess precision

Labbé, Anton, Ström, Benjamin January 2021 (has links)
The concept of a robotic manipulator is widely used throughout many industries. In this project, a manipulator of the type SCARA, selective compliance articulated robot arm, is constructed. The aim was to examine how such a robot could be constructed using 3D-printing and how accurate it would be. Other than 3D-printing, parts in the form of guiding rods, lead screw, bearings, pulleys and timing belts were used. Together with a microcontroller, the robot operates using three stepper motors. In the end it resulted in a SCARA with reasonable accuracy considering the methods used, more specifically the largest average error was 3.6cm in the X direction and 2.3 cm in the Y direction. The largest drawback of the final construction was the negative balance between tightening the belts and friction in the inner joint. Tightening the belts meant larger friction and thereby undesired movement properties. Doing the opposite meant that the belts could start slipping and enabled backlash. / Konceptet av en robotarm används brett inom många industrier. Detta projekt syftar till att konstruera en robot avtypen SCARA, selective compliance articulated robot arm. Målet var att undersöka hur en sådan robot kan 3D-printas och dess precision. Förutom 3D-printade delar användes även guidestänger, kullager, kamremmar och remskivor. Robotens rörelser styrs tillsammans med en mikrokontroller och tre stegmotorer. Med tillvägagångssätten i åtanke resulterade projektet in en SCARA med rimlig precision. Mer specifikt var medelfelet 3.6 cm i X-led och 2.3 cm i Y-led. Den största nackdelen med den slutgiltiga konstruktionenvar den negativa jämvikten mellan att spänna kamremmarna och friktionen i den inre armleden. Att spänna kamremmarna innebar en ökning i friktion och därmed oönskade rörelseegenskaper. Att göra tvärtom innebar att bältena löpte större risk att glida ur och möjliggjorde dödgång.
19

Inverse identification of anisotropy and hardening using novel test specimen

Lim, Jan Rassel, Nilsson, Oliver January 2024 (has links)
Background. In today's industry, sheet metal forming is widely used for manufacturing products. Knowledge about the behaviour of sheet metal is crucial to avoid phenomena that negatively impact the manufactured components. Extensive research has been conducted to capture aspects of this behaviour, such as plastic anisotropy and strain hardening. Mathematical models have been proposed to describe these phenomena, typically requiring material-specific constants for improved accuracy. These models are important as they are leveraged in finite element simulations which are essential for the sheet metal industry. However, conventional methods for identifying these constants often require multiple tests and time-consuming calibration. Aim and Objectives. The aim of this thesis is to improve the efficiency of the material identification procedure of anisotropy and hardening by using a novel test specimen. To achieve the aim, the objectives include designing a test specimen, proposing an identification methodology and to compare the efficiency with existing identification techniques. Method. Two studies were conducted, a numerical study and an experimental study. In the experimental study, experimental data was used as target data in the optimization, while the numerical study utilized data from a finite element simulation with reference parameters as target data. A novel specimen geometry was designed by combining one plane-strain and two shear test specimens to cover multiple strain states. The inverse identification technique finite element model updating method was chosen for both studies. Additionally, the plastic anisotropy was modelled by using the YLD2000-2D yield function and the strain hardening was modelled by using Swift's hardening law. Result and Discussion. The identified parameters in the numerical study show discrepancies, but the identification errors are comparable to similar studies. During the verification, the identified parameters were mostly able to capture the reference behaviour. In the experimental study, the identified parameters showed significant deviations during the verification which may stem from factors such as geometric deviations, noise in data and phenomena such as twisting and bending in the physical test not being captured by the simulation models. Conclusions. The efficiency of determining the anisotropy parameters and the hardening parameters was improved when utilizing the proposed methodology and test specimen. The proposed methodology requires one less experimental test compared to the conventional identification method and does not require further calibration to determine both the anisotropy and hardening parameters compared to related studies. / Bakgrund. I dagens industri så är plåtformning använd i stor utsträckning för att tillverka produkter. Kunskap om beteendet av plåt är väsentligt för att undvika fenomen som negativt påverkar de tillverkade komponenterna. Omfattande forskning har utförts för att fånga olika aspekter av detta beteende, som plastisk anisotropi och deformationshärdning. Matematiska modeller har blivit föreslagna för att beskriva dessa fenomen, som typiskt kräver material-specifika konstanter för förbättrad noggrannhet. Dessa modeller är viktiga eftersom de är använda i finita element simulationer som är väsentliga för plåtformningsindustrin. Dock så behöver konventionella metoder för att identifiera dessa konstanter ofta flera tester och tidskonsumerande kalibrering. Syfte och Målen. Syftet med detta examensarbete är att förbättra effektiviteten för materialidentifieringsproceduren för anisotropi och härdning genom att använda en ny testbit. För att uppnå syftet så inkluderar målen att konstruera en testbit, föreslå en identifieringsmetodik och att jämföra effektiviteten med existerande identifieringstekniker. Metod. Två studier var utförda, en numerisk studie och en experimentell studie. I den experimentella studien så användes experimentell data som måldata i optimeringen, medan den numeriska studien använde data från en finita element simulation med referensparametrar som måldata. En ny testbit var konstruerad genom att kombinera en plan-töjning och två skjuvnings-testbitar för att täcka flera töjningstillstånd. Invers-identifieringstekniken finita-element-modell-uppdatterings metoden val-des för båda studierna. Den plastiska anisotropin var modellerad genom användning av YLD2000-2D flytfunktionen och deformationshärdningen var modellerad genom Swifts härdningslag. Resultat och Diskussion. De identifierade parametrarna i numeriska studien visar skiljaktigheter, men identifieringsfelen är jämförbara med liknande studier. Under verifieringen så kunde de identifierade parametrarna mestadels fånga referensbeteendet. I den experimentella studien så visades signifikanta avvikelser under verifieringen, som kan bero på faktorer som geometriska avvikelser, brus i datan och att fenomen som vridning och böjning i det fysiska testet inte kunde fångas av simulationsmodellerna. Slutsatser. Effektiviteten för bestämningen av anisotropi parametrarna och härdnings parametrarna var förbättrad genom att använda den föreslagna metodiken och testbiten. Den föreslagna metodiken behöver ett färre experimentellt test jämfört med den konventionella identifieringsmetoden och behöver inte vidare kalibrering för att bestämma både anisotropi och härdningsparametrarna, jämfört med relaterade studier.
20

An?lise estrutural da deforma??o cenoz?ica na Bacia de Cumuruxatiba (BA)

Ferreira, Talles Souza 03 September 2010 (has links)
Made available in DSpace on 2015-03-13T17:08:29Z (GMT). No. of bitstreams: 1 TallesSF_DISSERT_1-74.pdf: 3503129 bytes, checksum: 43d4d5f0a963aecc3dec332abad3bc2d (MD5) Previous issue date: 2010-09-03 / The Cumuruxatiba basin is located at the southern coast State of Bahia in northeastern of Brazil. This basin was formed in distensional context, with rifting and subsequent thermal phase during Neocomian to late Cretaceous. At Cenozoic ages, the Abrolhos magmatism occurs in the basin with peaks during the Paleocene and Eocene. In this period, there was a kinematic inversion in the basin represented by folds related to reverse faults. Structural restoration of regional 2D seismic sections revealed that most of the deformation was concentrated at the beginning of the Cenozoic time with the peak at the Lower Eocene. The post-Eocene is marked by a decrease of strain rate to the present. The 3D structural modeling revealed a fold belt (trending EW to NE-SW) accommodating the deformation between the Royal Charlotte and Sulphur Minerva volcanic highs. The volcanic eruptions have caused a differential overburden on the borders of the basin. This acted as the trigger for halokinesis, as demonstrated by physical modeling in literature. Consequently, the deformation tends to be higher in the edges of the basin. The volcanic rocks occur mainly as concordant structures (sills) in the syn-tectonic sediment deposition showing a concomitant deformation. The isopach maps and diagrams of axis orientation of deformation revealed that most of the folds were activated and reactivated at different times during the Cenozoic. The folds exhibit diverse kinematic patterns over time as response to behavior of adjacent volcanic highs. These interpretations allied with information on the petroleum system of the basin are important in mapping the prospects for hydrocarbons / A Bacia de Cumuruxatiba est? localizada no extremo sul da costa do Estado da Bahia, no Nordeste do Brasil. Esta bacia foi formada em ambiente distensional, com rifteamento e posterior fase termal durante o Neocomiano at? final do Cret?ceo. Durante o Cenoz?ico ocorre o magmatismo de Abrolhos na bacia com picos durante o Paleoceno e Eoceno. Neste per?odo ocorre uma invers?o cinem?tica na bacia representada por dobras relacionadas a falhas reversas. Restaura??es estruturais regionais de se??es s?smicas 2D, revelaram que a maior parte da deforma??o est? concentrada no inicio do Cenoz?ico com o pico no Eoceno Inferior. O per?odo p?s-Eoceno ? marcado pela diminui??o da taxa de deforma??o at? o presente. A modelagem estrutural 3D revelou uma frente de dobras (de orienta??o E-W variando para NE-SW) acomodando a deforma??o entre os altos vulc?nicos de Royal Charlotte e Sulphur Minerva. Os derrames vulc?nicos causaram uma sobrecarga diferencial nas bordas da bacia que serviu de gatilho para atua??o da halocinese, como j? demonstrado em modelagens f?sicas na literatura. Consequentemente, a deforma??o tende a ser maior na bordas da bacia. As rochas vulc?nicas ocorrem principalmente como estruturas concordantes (sills) nos sedimentos sin-tect?nicos revelando uma deposi??o concomitante ? deforma??o. O estudo dos mapas de is?pacas e diagramas com orienta??o do eixo de deforma??o revelaram que maior parte das dobras foram ativadas e reativadas em diferentes per?odos durante o Cenoz?ico. As dobras apresentam padr?es cinem?ticos variados ao longo do tempo que refletem a atua??o diferencial dos altos vulc?nicos adjacentes. Estas interpreta??es aliadas a informa??es sobre os sistemas petrol?feros da bacia s?o importantes no mapeamento dos prospectos para hidrocarbonetos

Page generated in 0.0355 seconds