• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2847
  • 968
  • 566
  • 403
  • 380
  • 199
  • 93
  • 71
  • 69
  • 57
  • 56
  • 51
  • 51
  • 45
  • 33
  • Tagged with
  • 6903
  • 560
  • 528
  • 495
  • 484
  • 478
  • 448
  • 429
  • 420
  • 402
  • 383
  • 362
  • 353
  • 351
  • 336
  • 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.
341

Génération de maillage à partir d'images 3D en utilisant l'adaptation de maillage anisotrope et une équation de réinitialisation / Direct multiphase mesh generation from 3D images using anisotropic mesh adaptation and a redistancing equation

Zhao, Jiaxin 03 March 2016 (has links)
Ces dernières années, les techniques d'imagerie ont fait l'objet de beaucoup d'améliorations. Elles permettent de fournir des images numériques 2D ou 3D précises de zones parfois invisibles à l’œil nu. Ces techniques s'appliquent dans de nombreux domaines comme l'industrie cinématographique, la photographie ou l'imagerie médicale... Dans cette thèse, l'imagerie sera utilisée pour effectuer des simulations numériques en la couplant avec un solveur éléments finis. Nous présenterons, en premier lieu, la morphologie mathématique et la méthode d'immersion d'image. Elles permettront l'extraction d'informations permettant la transformation d'une image dans un maillage exploitable. Puis, une méthode itérative d'adaptation de maillage basée sur un estimateur d'erreur sera utilisée afin de construire un maillage optimal. Ainsi, un maillage sera construit uniquement avec les données d'une image. Nous proposerons également une nouvelle méthodologie pour construire une fonction régulière a l'aide d'une méthode de réinitialisation de la distance signée. Deux avantages sont à noter : l'utilisation de la fonction régularisée permet une bonne adaptation de maillage. De plus, elle est directement utilisable par le solveur éléments finis. Les simulations numériques sont donc réalisées en couplant éléments finis stabilisés, adaptation de maillage anisotrope et réinitialisation. L'objectif de cette thèse est donc de simplifier le calcul numérique à partir d'image, d'améliorer la précision numérique, la construction d'un maillage automatique et de réaliser des calculs numériques parallèles efficaces. Les applications envisagées peuvent être dans le domaine médical, de la physique des matériaux ou du design industriel. / Imaging techniques have well improved in the last decades. They may accurately provide numerical descriptions from 2D or 3D images, opening perspectives towards inner information, not seen otherwise, with applications in different fields, like medicine studies, material science or urban environments. In this work, a technique to build a numerical description under the mesh format has been implemented and used in numerical simulations when coupled to finite element solvers. Firstly, mathematical morphology techniques have been introduced to handle image information, providing the specific features of interest for the simulation. The immersed image method was then proposed to interpolate the image information on a mesh. Then, an iterative anisotropic mesh adaptation operator was developed to construct the optimal mesh, based on the estimated error concerning the image interpolation. The mesh is thus directly constructed from the image information. We have also proposed a new methodology to build a regularized phase function, corresponding to the objects we wish to distinguish from the image, using a redistancing method. Two main advantages of having such function are: the gradient of the regularized function performs better for mesh adaptation; the regularized function may be directly used for the finite element solver. Stabilized finite element flow and advection solvers were coupled to the constructed anisotropic mesh and the redistancing function, allowing its application to multiphase flow numerical simulations. All these developments have been extended in a massively parallel context. An important objective of this work is the simplification of the image based computations, through a modified way to segment the image and by coupling all to an automatic way to construct the mesh used in the finite element simulations.
342

Succession within the Context of Family Firms in the GGVV-Region : Individual and Organizational Level Factors

Göhlin, Anna, Anna-Maria, Lipovac January 2019 (has links)
Background: Succession is a crucial concern for family business owners where an issue of importance is to retain the control within the family. Succession is a planned process which must be put in place to rearrange the leadership from one family member to another. It is a fragile process which requires a precise and in- depth planning as a result of the different essence of family firms. One of the most thriving and successful entrepreneurship regions in Sweden is the GGVV-region, Gnosjö, Gislaved, Värnamo and Vaggeryd, located in south of Sweden and consists of many family firms. Most of the companies in the GGVV-region are successful, at the same time, family firms in this region manage to go through successions and keep the business within the family. However, there is a little research available on succession within the GGVV-region. Purpose: The purpose of this research is to discover and examine the individual- and organizational level factors involved in succession for family members within family firms in the GGVV-region. The study will also identify what challenges family firms in this region deal with during the succession process. Method: The research was made with a qualitative approach, using in-depth, semi-structured interviews to collect the data. Ten face-to-face interviews were conducted with family firm owners in order to gather information about the succession process. An inductive approach has been used to analyze and interpret the data. Conclusion: It was concluded that common individual level- and organizational level factors has a major impact and is of importance when it comes to the succession process within the GGVV-region. Furthermore, it was also found that challenges such as; understand the complexity, clear work description andreleasing the control tend to have a crucial role within the succession process.
343

Swedish Bank Directors' Perceptions of Extended Audit Reports

Pantsar, Malin, Josefsson Hillström, Tova January 2019 (has links)
Audited financial statements are the most substantial source of information concerning bank loan decisions, and investors mainly base their investment decisions on the financial statements in combination with the audit report. The financial crisis brought attention to the existing expectation gap between auditors and stakeholders. An attempt to narrow the gap has been done by IAASB. The new standards require auditors to provide additional information in the audit report. The purpose of the study is to investigate how the extended audit report is perceived by Swedish bank directors. The study has a quantitative research strategy with an experimental design. The experiment includes one control group and seven experimental groups, and the participating Swedish bank directors amounted up to 122. An ANCOVA is performed to test the research questions regarding the bank directors’ perceptions and decisions. The empirical findings and analysis reveal that the disclosure of the assurance level has a positive impact on bank directors’ confidence in the financial statements, perceived quality of the audit report, perceived value of the information the audit report contains, as well as the probability of granting a credit. The results also indicate a significance for key audit matters (KAM) regarding the perceived value of information, meaning that the disclosure of KAM improves bank directors’ perceptions of the informational value the audit report contains. The disclosure of the materiality level does not appear to have a significant impact on the extending of the audit report, implying that a disclosure of the applied materiality level may not be beneficial for bank directors’ perceptions and decisions.
344

Variações na acumulação de matéria orgânica, ao longo do holoceno, em sedimentos da região costeira de Ubatuba-São Paulo / Changes in the organic matter accumulation, during holocene, in coastal sediments from Ubatuba region-São Paulo

Sonvesso, Simone Sandra 02 April 2007 (has links)
Mudanças na taxa de acumulação e na natureza da matéria orgânica sedimentar, e suas relações com as variações climáticas e flutuações do nível relativo do mar durante os últimos 8.500 anos cal. A.P. foram investigadas em dois testemunhos provenientes do Saco de Ribeira, Enseada do Flamengo, e junto à praia do Lázaro, Enseada da Fortaleza, na região de Ubatuba, litoral norte do Estado de São Paulo. Para o estudo as amostras coletadas foram submetidas a diversas análises - granulometria, teor de CaCO3, teores de Carbono orgânico, Nitrogênio e Enxofre totais, e razões isotópicas de carbono. Datações 14C, calibradas para a idade calendário, permitiram estabelecer um modelo de idades para as variações sedimentares detectadas. Intervalos de clima mais quente, 8.000-6.000 anos cal. A.P., foram acompanhados de um aumento na taxa de acumulação de carbono T.A.C. (10-13 g m-2 ano-1), seguida de diminuição após 5.000 anos cal. A.P., para valores inferiores a 2 g m-2 ano-1. Variações climáticas regionais, possivelmente relacionadas a chuvas torrenciais, próximos ao máximo transgressivo, de 5.100 anos 14C A.P., foram detectadas pelo aumento nos valores de T.A.C. (10-12 g. m- 2 ano-1), aumento nas taxas de acumulação de massa (T.A.M.) e deposição de sedimentos mais grossos, acompanhados de aumento na tendência continental da natureza da matéria orgânica. As maiores tendências continentais da matéria orgânica sedimentar, registradas aproximadamente entre 1.500-1.200 anos cal. A.P., podem ser decorrentes de uma oscilação negativa do nível do mar. No geral, todos os resultados estão de acordo com as curvas de variação do nível relativo do mar, já descritas na literatura. As análises sedimentares da região estudada revelaram um evento regressivo-trangressivo, que ainda não havia sido referido para o Estado de São Paulo. A partir de ~2.000 anos cal. A.P., o mar teria atingido um nível mais baixo que o atual, com o mínimo provavelmente entre 1.500-1.200 anos cal. A.P., e encontra-se em ascensão até os dias atuais. As características anóxicas e a matéria orgânica sedimentar de origem planctônica registradas junto à praia do Lázaro, em meio a condições de energia relativamente mais alta, em ~900 anos cal. A.P., foram consideradas como resultado de condições óxicas das águas, acompanhadas de altas taxas de produtividade, e subseqüente degradação da matéria orgânica, existentes no período anterior. / Changes in the organic carbon accumulation rates (Corg A.R.) and organic matter source characteristics and their relation to climate and relative sea level changes during the last 8.500 cal. yr. B.P. were investigated in two sediment cores from 2 embayments - Flamengo and Fortaleza inlets - northern coast of São Paulo State. Sediment samples were analysed for grain size, organic Carbon, total Nitrogen and Sulphur contents, and ?13C ratio. Radiocarbon datings provided a model age to the sedimentary deposits. The warm climate interval 8.000-6.000 cal. yr. B.P. was accompanied by an increase in the Corg A.R. (10-13 g.m.-2 yr -1) and a decrease (~2 g.m.-2 yr -1) in the last ~5.000 cal. yr. B.P. Regional climate changes, as stormy weather, that may have ocurred near the maximum transgressive period called Santos Transgression at 5.100 yr. B.P., were recorded in the sedimentary profiles by relatively hight T.A.C. and T.A.M. values, coaser grain size sediment delivery, and enhanced terrestrial organic matter source characteristics. Improvement of terrestrial origin of the sedimentary organic matter recorded between 1.500-1.200 cal. yr. B.P in the studied area was mainly related to a negative sea-level oscillation. All the results are in general agreement with the existing sea level change curves. The sedimentary profiles suggest a negative sea-level fall event, that had\'nt been described yet for São Paulo State. It\'s proposed that the negative oscillation would have begun at ~2.000 cal. yr. B.P.and reached a minimum probably between 1.500-1200 cal. yr. B.P. The relative sea level has been rising since then. Anoxic conditions accompanied by algal origins of sedimentary organic matter, observed in the sedimentary profile from Fortaleza inlet at 900 cal. yr. B.P, during a more oxidizing environment are considered as a result of a previous well oxygencontaining water column and high productivity rates.
345

Reconstruction 3D de vaisseaux sanguins / 3D reconstruction of blood vessels

Al Moussawi, Ali 17 December 2014 (has links)
Ce travail concerne la reconstruction 3D de vaisseaux sanguins à partir de coupes transversales en nombre éventuellement réduit. Si des données sont manquantes, une reconstruction cohérente avec un réseau de vaisseaux est obtenue. Cette approche permet en outre de limiter les interventions humaines lors du traitement des images des coupes transversales 2D. Sachant que les images utilisées sont obtenues par scanner,la difficulté est de connecter les vaisseaux sanguins entre deux coupes espacées pour obtenir un graphe qui correspond au cœur des vaisseaux. En associant les vaisseaux sanguins sur les coupes à des masses à transporter, on construit un graphe solution d’un problème de transport ramifié. La reconstruction 3D de la géométrie résulte des données 2D d’imagerie issues des différentes coupes transversales et du graphe. La géométrie 3D des vaisseaux sanguins est représentée par la donnée d’une fonction Level Set définie en tout point de l’espace dont l’iso-valeur zéro correspond aux parois des vaisseaux. On s’intéresse ensuite à résoudre numériquement le modèle de Navier-Stokes en écoulement incompressible sur un maillage cartésien inclus dans la géométrie reconstruite. Ce choix est motivé par la rapidité d’assemblage du maillage et des opérateurs discrets de dérivation, en vue d’éventuelles déformation des vaisseaux. L’inadaptation du maillage avec l’interface de la géométrie amène à considérer une condition limite modifiée permettant un calcul consistant des contraintes aux parois. / This work concerns the 3D reconstruction of blood vessels from a limited number of 2D transversal cuts obtained from scanners. If data are missing, a coherentreconstruction with a vessel network is obtained. This approach allows to limit human interventions in processing images of 2D transversal cuts. Knowing that the images used are obtained by scanner, the difficulty is to connect the blood vessels between some widely spaced cuts in order to produce the graph corresponding to the network of vessels. We identify the vessels on each trnasversal cut as a mass to be transported, we construct a graph solution of a branched transport problem. At this stage, we are able to reconstruct the 3D geometry by using the 2D Level Set Functions given by the transversal cuts and the graph information. The 3D geometry of blood vessels is represented by the data of the Level Set function defined at any point of the space whose 0-level corresponds to the vessel walls. The resulting geometry is usually integrated in a fluid mechanic code solving the incompressible Navier-Stokes equations on a Cartesian grid strictly included in a reconstructed geometry. The inadequacy of the mesh with the interface of the geometry is overcomed thanks to a modified boundary condition leading to an accurate computation of the constraints to the walls.
346

The Effects of Teacher Education Level, Teaching Experience, And Teaching Behaviors On Student Science Achievement

Zhang, Danhui 01 December 2008 (has links)
Previous literature leaves us unanswered questions about whether teaching behaviors mediate the relationship between teacher education level and experience with student science achievement. This study examined this question with 655 students from sixth to eighth grade and their 12 science teachers. Student science achievements were measured at the beginning and end of 2006-2007 school year. Given the cluster sampling of students nested in classrooms, which are nested in teachers, a two-level multilevel model was employed to disentangle the effects from teacher-level and student-level factors. Several findings were discovered in this study. Science teachers possessing of advanced degrees in science or education significantly and positively influenced student science achievement. However, years of teaching experience in science did not directly influence student science achievement. A significant interaction was detected between teachers possessing an advanced degree in science or education and years of teaching science, which was inversely associated to student science achievement. Better teaching behaviors were also positively related to student achievement in science directly, as well as mediated the relationship between student science achievement and both teacher education and experience. Additionally, when examined separately, each teaching behavior variable (teacher engagement, classroom management, and teaching strategies) served as a significant intermediary between both teacher education and experience and student science achievement. The findings of this study are intended to provide insights into the importance of hiring and developing qualified teachers who are better able to help students achieve in science, as well as to direct the emphases of ongoing teacher inservice training.
347

Assessment of Links between Sea Level Variations and Climate Variability and Change

Unknown Date (has links)
A comprehensive study is conducted to evaluate global sea levels for trends and variations due to climate change and variability by using non-parametric methods. Individual and coupled effects of inter-annual ENSO, decadal PDO, multi-decadal AMO, and quasi-decadal NAO on sea levels are evaluated. Combined influences of different phases (cool or warm) of PDO, AMO, and NAO influences and ENSO are also evaluated. The results from this study showed that sea level at 60% of the sites is increasing with time with all four oscillations impacting global sea levels. AMO warm phase individually and PDO warm combined with La-Niña phase contribute to higher sea levels throughout the world. Trends and variations in sea levels are noted to be spatially non-uniform. Understanding and quantifying climate variability influenced variations in sea levels and assessment of long-term trends enables protection of coastal regions of the world from sea level rise. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection
348

Environmental radiation monitoring at the low level radioactive waste storage facility in Siu A Chau and development of a particle dispersion model in marine environment

Chiu, Yu-yeung. January 2006 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.
349

The formalization and realization level in Namibian schools : An investigation of two countryside schools

Herdin, Fanny, Nilsson, Helena January 2009 (has links)
<p>The aim of this thesis is to find out if there is a gap between the formalization level and the realization level in the Namibian school system. Moreover, our aim is to figure out how we, as visiting teaching students, interpret the relationship between steering documents and the teaching in the classroom. In turn, the aim was used to formulate three different research questions: What can we experience while observing in the class room/at school? What do the interviewed teachers express concerning our asked questions? What are the main differences between the two latest steering documents?</p><p>The reason why we decided to do a study about the school system in Namibia is because it is a young country, it was proclaimed independent in 1990. Therefore we think it is interesting to study how the school system and its political steering documents have developed over the years.</p><p>Our theoretical framework includes the concept of curriculum, reconceptualism and cultural issues. Our focal point has been on the following three perspectives, democracy, gender and learner centred education.</p><p>The method we used in this study is triangulation, in this case analyzing political steering documents, interviewing teachers and other people connected to the school and finally class room observations. The attitudes to the three above mentioned perspectives vary amongst the interviewed personnel This study as come to the conclusion that there is a gap between the formalization level and realization level.</p>
350

Holocene sea level history and reef development in Hawaii and the Central Pacific Ocean

Grossman, Eric E. January 2001 (has links)
Thesis (Ph. D.)--University of Hawaii at Manoa, 2001. / Heading on microfiche: Grossman, Eric Edward. Includes bibliographical references (leaves 238-257). Also available on microfiche.

Page generated in 0.0497 seconds