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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Aplicación de la guia Pmbok en el desarrollo de un proyecto educativo

Cabellos Rafael, Johanna Milena January 2012 (has links)
This thesis attempts to convey the importance of good project management and the advantages to offer the standard PMBOK. This standard is only a guide to "Best Practices" that does not mean that the knowledge described should always be applied uniformly across all projects: the project management team is responsible for determining what is appropriate for each particular project. Within the thesis developed the following plans and recommendations for each: Plan Scope Management, Plan time management, plan cost management, plan quality management, Plan human resources management, plan communication management, Plan risk management, and Plan procurement management.
2

Aplicación de la guia del PMBOK en el desarrollo de un proyecto Educativo

Cabellos Rafael, Johanna Milena January 2012 (has links)
El crecimiento del Producto Bruto Interno en el sector construcción en el Perú presenta un ritmo sostenido durante varios años y las perspectivas son igualmente buenas, el mantenimiento de tales condiciones exige que se aplique una metodología que ayude a incrementar las probabilidades de lograr que los proyectos del sector construcción sean mayormente exitosos. Actualmente la ejecución de los proyectos de construcción viene caracterizados por una problemática cuyos signos o diagnósticos son frecuentemente: • No definir bien el alcance del proyecto. • No terminar a tiempo los proyectos. • Terminar el proyecto con compromisos potenciales que obligan a incrementar el servicio de Post - Venta. • Terminar con altos costos relativos a la calidad, particularmente con costos de no calidad. Esta situación ha generado la necesidad del planteamiento de la implementación y aplicación de la guía de los fundamentos para la dirección de proyectos PMBOK en el sector de construcción para lograr proyectos más exitosos. 4) Objetivos : Formular recomendaciones para implementar los procesos, conocimientos, herramientas y técnicas de la guía de los fundamentos de proyectos (Guía PMBOK) para obtener un proyecto exitoso, manteniendo los altos estándares de integridad y conducta. 5) Hipótesis : Debido a que los proyecto de construcción son muy complejos durante sus diferentes etapas, en esta tesis se Aplicara la Guía del Pmbok ® ya que esta facilitará y proporcionara herramientas y técnicas para obtener un proyecto exitoso, satisfaciendo los requerimientos del proyecto. 6) Metodología : Se empleara la recolección de información de manera cualitativa, desarrollando asignación de matrices, mediciones de desempeño; empleando el programa WBS (Work Breakdown Structure) para obtener la estructura detallada del proyecto; como el MS Project para obtener el cronograma del proyecto. La metodología se aplicará al caso específico del Proyecto de la Institución Educativa Santa Ana – Chincha Alta provincia de Ica. Del estudio realizado mediante la GUIA DEL PMBOK (A Guide to the Project Management Body of Knowledge) se extraerán recomendaciones para la aplicación futura en obras similares. 7) Resultados : • Es necesario invertir tiempo en la planificación, este es un principio básico de la calidad. Invertir el tiempo en la planeación, ahorra tiempo en la ejecución, al analizar previamente el cambio que se ha de seguir y por lo tanto evitar re trabajos, los mismos que normalmente repercuten en desviaciones de tiempo y en mayores costos. Más aun, el trabajo de planificación, es mucho más barato que el de ejecución, por lo que siempre es bueno tener en mente que ningún proyecto es tan urgente como para no dedicar tiempo suficiente a su planificación. • Es preciso tratar de prevenir los problemas antes de que ocurran, un buen análisis de los riesgos a los que se enfrenta un proyecto, puede minimizar o eliminar por completo un riesgo, mucho contratiempos y problemas a los que los proyectos se enfrentan. La gestión de los riesgos en un proyecto se ha convertido en una herramienta muy utilizada hoy en día. • Finalmente es necesario invertir el tiempo suficiente al cierre de un proyecto, la principal razón para detenerse al final de un proyecto y hacer un análisis de lo que ocurrió, es aprender del mismo para repetir en proyectos futuros aquello que funcionó y evitar lo que no. Aparte de la meta cumplida, los productos más importantes que se obtiene al final de un proyecto son las lecciones aprendidas. 8) Conclusiones : • Se puede concluir del análisis efectuado que la que la aplicación de las 9 áreas de conocimiento de la Guía del Pmbok, tendrá un impacto positivo en el desarrollo de un proyecto de construcción. • Del caso estudiado se concluye que, si durante la planificación del proyecto se hubiera realizado un enunciado del alcance detallado y descrito con mayor información y a la vez desarrollado la Estructura del Desglose de trabajo (EDT) conforme a la recomendación del Pmbok, los miembros del equipo del proyecto se hubieran percatado a tiempo de las precisiones o modificaciones requeridas para obtener un producto con las especificaciones necesarias para su aceptación por el cliente. • También se puede concluir que si dentro de la organización no existe una política de calidad, el equipo del proyecto deberá desarrollarla y se hará responsable de que todos los participantes estén plenamente enterados de esta. Dentro del plan de gestión de calidad el equipo del proyecto debe identificar los requisitos y las normas de calidad que deben ser cumplidos durante el ciclo de vida del proyecto de construcción. Cumplir con los requisitos de la calidad permitirá menor re-trabajo, alta productividad, costos reducidos y satisfacción del cliente. • También podemos concluir que todos los proyectos que no gestionan los riesgos están en mayor riesgo. Aunque es inútil tratar de eliminar el riesgo y cuestionable intentar minimizarlo, es esencial que los riesgos que se tomen sean los riesgos correctos. • El estándar del PMBOK es sólo una guía de “Buenas Prácticas”, lo que no quiere decir que los conocimientos descritos deban aplicarse siempre de manera uniforme en todos los proyectos: el equipo de dirección del proyecto debe ser el responsable de determinar lo que es apropiado para cada proyecto determinado.
3

Implementación de Planeamiento Específico para Proyectos de Viviendas de Sector a con Tiempo reducido de Ejecución

Romero Borda, Anthony Nicasio, Tullume Uceda, Víctor Miguel, Fernández Dávila Zúñiga, Claritza Alejandra, Gómez Plasencia, Richard Jhosimar 02 December 2019 (has links)
Teniendo en cuenta la demanda actual de viviendas en el Sector A en Lima Metropolitana, así como la aplicación de diferentes metodologías en el sector construcción con el propósito de desarrollar proyectos dentro del costo, tiempo y de calidad planeados, es que se ha tomado como objeto de estudio el proyecto de construcción de un edificio de vivienda bifamiliar del sector A, con un plazo de ejecución de 6 meses, considerando un alcance de construcción hasta la etapa Casco y en la modalidad de Suma Alzada. El objetivo del presente trabajo de investigación es desarrollar un planeamiento específico para proyectos de vivienda en el sector A en un tiempo reducido para minimizar los sobrecostos y cumplir con el plazo de obra. Por tal motivo, se han identificado los problemas suscitados durante la construcción de la obra, entre los que se encuentran las incompatibilidades del proyecto, inadecuado planeamiento, cambios en el diseño, cambios de alcance y retrabajos en obra. Seguidamente se ha diagnosticado la repercusión de estos problemas en el presupuesto meta, plazo de ejecución y calidad de la edificación, para finalmente elaborar un plan de acción en donde se presenta de manera detallada el Organigrama de obra, el EDT y Cronograma de obra, Modelado y sectorización, gestión de riesgos y cambios aplicados al proyecto y por último un Diagrama de Pareto aplicado al presupuesto meta. Finalmente se realiza la evaluación del costo de implementación del plan de acción con el propósito de que se pueda ser aplicable a otras construcciones de similares características. / Taking into account the current demand for housing in Sector A in Metropolitan Lima, as well as the application of different methodologies in the construction sector with the purpose of developing projects within the planned cost, time and quality, is that it has been taken as a study object the construction project of a two-family housing building in Sector A, with an execution time of 6 months, considering a scope of construction until the Casco stage and in the modality of “Suma Alzada”. The objective of this research work is to develop a specific planning for housing projects in sector A in a reduced time to minimize cost overruns and meet the construction deadline. For this reason, the problems that have arisen during the construction of the work have been identified, among which are the incompatibilities of the project, inadequate planning, changes in design, changes in scope and rework on site. Next, the repercussion of these problems on the target budget, execution time and quality of the building was diagnosed, and finally an action plan was drawn up, in which the work organization chart, the WBS and work schedule, modeling and sectoring, risk management and changes applied to the project were presented in detail, and finally a Pareto diagram applied to the target budget. Finally, the cost of implementing the action plan is evaluated so that it can be applied to other constructions of similar characteristics. / Trabajo de investigación
4

Structural study of nano-structured materials: electron crystallography approaches

Ma, Yanhang January 2016 (has links)
The structural analysis serves as a bridge to link the structure of materials to their properties. Revealing the structure details allows a better understanding on the growth mechanisms and properties of materials, and a further designed synthesis of functional materials. The widely used methods based on X-ray diffraction have certain limitations for the structural analysis when crystals are small, poorly crystallized or contain many defects. As electrons interact strongly with matter and can be focused by electromagnetic lenses to form an image, electron crystallography (EC) approaches become prime candidates for the structural analysis of a wide range of materials that cannot be done using X-rays, particularly nanomaterials with poor crystallinity. Three-dimensional electron diffraction tomography (3D EDT) is a recently developed method to automatically collect 3D electron diffraction data. By combining mechanical specimen tilt and electronic e-beam tilt, a large volume of reciprocal space can be swept at a fine step size to ensure the completeness and accuracy of the diffraction data with respect to both position and intensity. Effects of the dynamical scattering are enormously reduced as most of the patterns are collected at conditions off the zone axes. In this thesis, 3D EDT has been used for unit cell determination (COF-505), phase identifications and structure solutions (ZnO, Ba-Ta3N5, Zn-Sc, and V4O9), and the study of layer stacking faults (ETS-10 and SAPO-34 nanosheets). High-resolution transmission electron microscope (HRTEM) imaging shows its particular advantages over diffraction by allowing observations of crystal structure projections and the 3D potential map reconstruction. HRTEM imaging has been used to visualize fine structures of different materials (hierarchical zeolites, ETS-10, and SAPO-34). Reconstructed 3D potential maps have been used to locate the positions of metal ions in a woven framework (COF-505) and elucidate the pore shape and connectivity in a silica mesoporous crystal. The last part of this thesis explores the combination with X-ray crystallography to obtain more structure details.
5

Estudo de dieta total aplicado na avaliação de ingestão de elementos essenciais, tóxicos e radionuclídeos naturais nas populações urbana e rural de Poços de Caldas / Total diet study applied in the evaluation of ingestion of essential, toxic elements, and natural radionuclides in the urban and rural populations of Poços de Caldas

Mychelle Munyck Linhares Rosa 30 May 2018 (has links)
A segurança alimentar é uma necessidade fundamental e de grande preocupação pública em todo o mundo. A Organização Mundial de Saúde (WHO) recomenda o Estudo de Dieta Total (EDT) como sendo o método mais adequado de estimativa para as ingestões de contaminantes e nutrientes para um país ou grandes grupos populacionais. A implantação de um estudo relacionando a ingestão de alimentos em uma Região de Elevada Radioatividade Natural (HBRA) motivou o presente estudo, uma vez que no planalto de Poços de Caldas há ocorrência de anomalias radiativas com concentrações naturais significativas de urânio e tório. O presente estudo teve por objetivo avaliar e comparar as ingestões de elementos essenciais, tóxicos e radionuclídeos, a partir dos alimentos que compõem as dietas das populações urbana e rural, da cidade de Poços de Caldas. As determinações das concentrações dos elementos essenciais e tóxicos foram realizadas aplicando-se a técnica de análise por ativação neutrônica (As, Ca, Cl, Co, Cr, Fe, K, Mg, Mn, Na e Zn), espectrometria de absorção atômica com forno de grafite (Cd, Cu e Pb) e por geração de vapor frio (Hg). As determinações dos radionuclídeos foram realizadas aplicando-se as técnicas de análise por espectrometria gama (40K), separação radioquímica seguida de contagem alfa e beta total (210Pb, 226Ra e 228Ra) e espectrometria alfa (210Po, 228Th, 230Th, 232Th, 234U, 235U e 238U). Os grupos de alimentos foram estabelecidos de acordo com os dados de consumo da região sudeste do país, obtidos pela Pesquisa Orçamentária Familiar (POF) 2008-2009 do Instituto Brasileiro de Geografia e Estatística (IBGE). A lista final totalizou 82 alimentos distribuídos em 20 grupos, incluindo a água, e com massa total de 3,6180 Kg. Com o EDT aplicado para a região do Planalto de Poços de Caldas, foi possível observar que as ingestões diárias média para todos os elementos essenciais na dieta da população urbana apresentaram valores mais elevados quando comparados à dieta da população rural, porém não apresentaram diferenças estatisticamente significativas. As dietas estudadas foram deficientes nos elementos essenciais Ca, K, Mg e Se quando comparadas aos valores de ingestão diária recomendados. Os teores dos elementos tóxicos Cd e Pb no presente estudo estiveram dentro do intervalo relatado pela WHO a partir de EDT realizados em diversos países e/ou diferentes regiões no mundo. A ingestão total do elemento tóxico Hg foi encontrada muito abaixo do limite estabelecido pela WHO. Em relação aos radionuclídeos naturais, o cálculo de dose efetiva comprometida por ingestão da região rural (0,89 mSv/ano) apresentou-se 61% mais elevado quando comparado à região urbana (0,56 mSv/ano). Isto pode ser explicado pelo fato dos maiores pontos de anomalias radioativas estarem localizados na zona rural. Porém, a partir dos valores encontrados no presente estudo não apresentaram níveis que representassem ameaça à saúde da população deste planalto. / Food security is a fundamental need and a great public concern throughout the world. The World Health Organization (WHO) recommends the Total Diet Study (TDS) as the most appropriate method of estimating the intake of contaminants and nutrients for a country or large population groups. The implementation of a study relating food intake in a High Background Radiation Area (HBRA) motivated the present study, since in the Poços de Caldas plateau there are occurrences of radiative anomalies with significant natural concentrations of uranium and thorium. Therefore, the objective is to evaluate and to compare the intakes of essential, toxic elements, and radionuclides from the foods that composed the diets of the urban and rural populations of the city. The concentration determination of the essential and toxic elements was performed using the neutron activation analysis (As, Ca, Cl, Co, Cr, Fe, K, Mg, Mn, Na and Zn) and atomic absorption spectrometry with graphite furnace (Cd, Cu and Pb) and cold vapor atomic (Hg). The determination of radionuclides was performed by gamma spectrometry (40K), radiochemical separation followed by total alpha and beta counting (210Pb, 226Ra and 228Ra) and alpha spectrometry (210Po, 228Th, 230Th, 232Th, 234U, 235U and 238U). The food groups were established according to consumption data from the southeast region of the country obtained by the Household food budget survey POF 2008-2009 by the Brazilian Institute for Geography and Statistics (IBGE). The final list contained 82 foods distributed in 20 groups, including drinking water, and with a total mass of 3.6180 kg. The TDS applied to the region of the Poços de Caldas Plateau allowed to observe that the average daily intakes for all the essential elements in the urban population diet presented higher values compared to the diet of the rural population but did not present statistical differences. The essential elements Ca, K, Mg and Se were deficient in the diets studied compared to the recommended daily intake values. The toxic element level of Cd and Pb in the present study were within the range reported by the WHO from TDS conducted in several countries and/or different regions in the world. The total intake of the toxic element Hg was found well below the established limit by WHO. Intake effective dose compromised calculation of the rural region (0.89 mSv/year) was 61% higher compared to the urban region (0.56 mSv/year). This can be explained by the fact that the highest points of radioactive anomalies in the plateau are located in the rural zone, but the values found in the present study do not present levels that represent a threat to the health of the population in this plateau.
6

Theoretical And Experimental Investigation Of Residual Stresses In Electric Discharge Machining

Ekmekci, Bulent 01 January 2004 (has links) (PDF)
Electric Discharge Machining (EDM) is a process for eroding and removing material by transient action of electric sparks on electrically conductive materials immersed in a dielectric liquid and separated by a small gap. A spark-eroded surface is a surface with matt appearance and random distribution of overlapping craters. It is mechanically hard and stressed close to ultimate tensile strength of the material and sometimes covered with a network of micro cracks. The violent nature of the process leads a unique structure on the machined surface and generates residual stresses due mainly to the non-homogeneity of heat flow and metallurgical transformations. An extensive experimental study is presented to explore the surface and sub-surface characteristics together with the residual stresses induced by the process. Layer removal method is used to measure the residual stress profile in function of depth beneath. A finite element based model is proposed to determine residual stresses and compared with the experimental results. The residual stress pattern is found to be unchanged with respect to machining parameters. Thus, a unit amplitude shape function representing change in curvature with respect to removal depth is proposed. The proposed form is found as a special form of Gauss Distribution, which is the sum of two Gaussian peaks, with the same amplitude and pulse width but opposite center location that is represented by three constant coefficients. In each case, agreement with the proposed form is established with experimental results. Results have shown that these coefficients have a power functional dependency with respect to released energy.
7

The use and effectiveness of information system development methodologies in health information systems / Pieter Wynand Conradie.

Conradie, Pieter Wynand January 2010 (has links)
Abstract The main focus of this study is the identification of factors influencing the use and effectiveness of information system development methodologies (Le., systems development methodologies) in health information systems. In essence, it can be viewed as exploratory research, utilizing a conceptual research model to investigate the relationships among the hypothesised factors. More specifically, classified as behavioural science, it combines two theoretical models, namely the Unified Theory of Acceptance and Use of Technology and the Expectancy Disconfirmation Theory. The main aim of behavioural science in information systems is to assist practitioners (Le., social actors) in improving business processes and competitiveness, thus the effective use of information systems. A wider view of behavioural science incorporates other social actors (e.g., end users) and organisational actors (e.g., executives). In health information systems, the effective use of information systems is especially relevant Health information systems are vital in the area of health care, since only by having access to pertinent health information, can the correct decisions relating to diagnostics and curative procedures be made. The use of systems development methodologies in health information systems development is therefore crucial, since they can make the development process more effective, while improving software quality. By empirically evaluating the conceptual research model, utilizing a survey as the main research method and structural equation modelling as the main statistical technique, meaningful results were obtained. Focussing on the factors influencing the individual's behavioural intent, it was found that the compatibility of systems development methodologies to the developer's pre-existing software development style is vital. Furthermore, performance expectancy, self-efficacy, organisational culture, policies, customer influence, voluntariness and facilitating conditions, all directly influenced the use of systems development methodologies, with policies and customer influence playing a significant role, especially in relation to health information systems. No significant direct effects or indirect effects could be established for the factors effort expectancy, personal innovativeness and social influence. It appears that individuals working in the health care software development discipline are more autonomous, less influenced by others. Also, the lack of support for the factor effort expectancy may indicate that systems development methodologies have entered a mature state, with less concern on the effort required for use. Furthermore, with regard to effectiveness and the continued use of information systems methodologies, satisfaction had a significant direct effect, with confirmation having a significant indirect effect. Keywords: behavioural science; conceptual research model; direct effect; exploratory research; Expectancy Disconfirmation Theory; indirect effect; Unified Theory of Acceptance and Use of Technology; structural equation modelling; survey; systems development methodologies. / Thesis (Ph.D. (Computer Science))--North-West University, Potchefstroom Campus, 2010.
8

The use and effectiveness of information system development methodologies in health information systems / Pieter Wynand Conradie.

Conradie, Pieter Wynand January 2010 (has links)
Abstract The main focus of this study is the identification of factors influencing the use and effectiveness of information system development methodologies (Le., systems development methodologies) in health information systems. In essence, it can be viewed as exploratory research, utilizing a conceptual research model to investigate the relationships among the hypothesised factors. More specifically, classified as behavioural science, it combines two theoretical models, namely the Unified Theory of Acceptance and Use of Technology and the Expectancy Disconfirmation Theory. The main aim of behavioural science in information systems is to assist practitioners (Le., social actors) in improving business processes and competitiveness, thus the effective use of information systems. A wider view of behavioural science incorporates other social actors (e.g., end users) and organisational actors (e.g., executives). In health information systems, the effective use of information systems is especially relevant Health information systems are vital in the area of health care, since only by having access to pertinent health information, can the correct decisions relating to diagnostics and curative procedures be made. The use of systems development methodologies in health information systems development is therefore crucial, since they can make the development process more effective, while improving software quality. By empirically evaluating the conceptual research model, utilizing a survey as the main research method and structural equation modelling as the main statistical technique, meaningful results were obtained. Focussing on the factors influencing the individual's behavioural intent, it was found that the compatibility of systems development methodologies to the developer's pre-existing software development style is vital. Furthermore, performance expectancy, self-efficacy, organisational culture, policies, customer influence, voluntariness and facilitating conditions, all directly influenced the use of systems development methodologies, with policies and customer influence playing a significant role, especially in relation to health information systems. No significant direct effects or indirect effects could be established for the factors effort expectancy, personal innovativeness and social influence. It appears that individuals working in the health care software development discipline are more autonomous, less influenced by others. Also, the lack of support for the factor effort expectancy may indicate that systems development methodologies have entered a mature state, with less concern on the effort required for use. Furthermore, with regard to effectiveness and the continued use of information systems methodologies, satisfaction had a significant direct effect, with confirmation having a significant indirect effect. Keywords: behavioural science; conceptual research model; direct effect; exploratory research; Expectancy Disconfirmation Theory; indirect effect; Unified Theory of Acceptance and Use of Technology; structural equation modelling; survey; systems development methodologies. / Thesis (Ph.D. (Computer Science))--North-West University, Potchefstroom Campus, 2010.
9

Déformation à la transition entre subduction et collision à l'est de Taïwan: approche sismologique

Theunissen, Thomas 13 July 2011 (has links) (PDF)
Le but de ce travail est de préciser la déformation en mer à l'est de Taïwan et de notamment caractériser les failles actives majeures en particulier au niveau de l'avant-arc des Ryukyus. Le problème majeur associé à l'étude de cette région est que les séismes sont localisés en dehors des réseaux permanents et que cela conduit à des localisations peu précises limitant les analyses statistiques, tectoniques et donc l'estimation correcte de l'aléa sismique. Ce travail est inclus dans le projet ANR ACTS (Active Tectonics and Seismic Hazard in Taiwan). Pour atteindre cet objectif, nous travaillons à trois échelles de temps différentes pour lesquelles une méthode de localisation différente a été proposée pour obtenir une image précise de la déformation sismique et mettre en évidence les failles majeures en mer à l'est de Taïwan. D'abord, à l'échelle du siècle (à partir de l'analyse d'un catalogue de sismicité homogène en magnitude), les séismes historiques instrumentaux (1897-2007) montrent que la marge des Ryukyus a été affectée par 6 séismes de magnitude supérieure à 7 dont 4 pour lesquels la faille responsable n'est pas connue. Nous proposons une méthode de localisation relative qui permet de relocaliser les évènements historiques à partir des différences de temps d'arrivées P et S (Ts-Tp) à chaque station. La localisation est obtenue en recherchant les séismes analogues dans le catalogue instrumental récent (1991-2008) pour lesquels Ts-Tp à chaque station est proche. Cette méthode a été appliquée au plus gros séisme (en terme de magnitude) jamais enregistré à Taïwan, le séisme du 5 juin 1920 (M7.7 $\pm$ 0.2). Ce séisme a certainement pour origine une rupture sur l'interplaque sismogène de la subduction des Ryukyus avec une possible nucléation à la base d'une faille hors-séquence. Ensuite, à l'échelle de la dizaine d'années, l'amélioration de la méthode de localisation absolue du MAXimum d'Intersection EDT (MAXI, EDT: Equal Differential Time) permet de mieux extraire les temps d'arrivées erronés et empêche les "trade-off" entre profondeur et temps d'origine et, entre profondeur et position épicentrale lorsque la couverture azimutale est faible (gap azimutal > 180°). Des tests synthétiques montrent l'efficacité de MAXI (en utilisant les ondes P uniquement) à déterminer les paramètres x, y et z même lorsque le gap azimutal est important. Dans ce dernier cas, la qualité des résultats reste dépendant du modèle de vitesse à représenter la structure 3D de la Terre. Nous proposons une démarche associant l'utilisation d'un modèle de vitesse des ondes P 3D a priori avec la méthode MAXI pour localiser les séismes qui sont latéraux et éloignés du réseau. Une application au cas de Taïwan et en Équateur valide cette approche. Enfin, à l'échelle de quelques mois, la campagne de géophysique marine RATS (Ryukyu Arc: Tectonics and Seismology) a été menée en deux temps. Une expérience de sismologie passive de juillet à octobre 2008 (RATS1) a été menée au-dessus de l'avant-arc des Ryukyus puis une expérience de sismique active (réfraction et réflexion) a été menée en mai 2009 sur une ligne NNE-SSW à travers la marge des Ryukyus. Ces deux expériences combinées permettent d'améliorer notre connaissance de la structure crustale de la marge. Au niveau de l'avant-arc, le socle de l'avant-arc est caractérisé par une extrémité formant un butoir vertical et une base très déformée certainement associée à une importante déformation hors-séquence. En profondeur, la plaque plongeante est certainement affectée par une déchirure qui contrôle la sismicité dans cette région de transition entre la subduction et la collision.
10

Analysis of Passive Attitude Stabilisation and Deorbiting of Satellites in Low Earth Orbit

Hawe, Benjamin January 2016 (has links)
Orbital debris poses a serious threat to ongoing operations in space.  Recognising this threat, the European Commission has funded the three-year Technology for Self Removal (TeSeR) project with the goal of developing a standard scalable Post Mission Disposal (PMD) module to remove satellites from orbit following the completion of their mission.  As the project coordinator and key member of the TeSeR Project, Airbus Defence and Space Germany will invest significant resources in achieving this goal over the course of the project. This thesis details the initial analysis of potential PMD module designs conducted by the author during an internship within the AOCS/GNC department of Airbus Defence and Space Friedrichshafen between 1 April 2016 and 31 August 2016.  Three main concepts, drag sails, drag balloons and Electrodynamic Tethers (EDTs), were evaluated during this time with an emphasis on determining the ability of each design to permit passive attitude stabilisation of the satellite during PMD.  Following the required modification of a pre-existing MATLAB/Simulink model, several key findings were made for each device concept.  It was found that no drag sail designs investigated permitted passive aerodynamic attitude stabilisation at orbit heights above 550 km.  When deorbiting from 800 km, however, the lack of the desired and stable attitude was not found to have a significant increase on the deorbit time or the area‑time product. Drag balloon designs were predicted to be comparatively unstable and less mass efficient for deorbiting purposes, with area‑time products up to approximately 50 per cent higher than the equivalent mass drag sail designs.  In spite of this, unstable drag balloons were found to provide shorter deorbit times than stable balloons due to the contribution of the satellite body and solar array to the total frontal area of the satellite.  This indicated that attitude stabilisation is not required for satellites equipped with drag balloon devices. Modelling of bare EDTs suggested that tethers with lengths of 1000 metres or more would not permit passive attitude stabilisation at an orbit height of 800 km.  Simulation of a 500 metre EDT, however, indicated that passive attitude stabilisation can be achieved with EDT devices and proved that EDTs can generate significantly higher drag forces than aerodynamic devices while possessing a significantly lower device mass.  Following the analysis of these results, a recommendation was made for future work to be aimed at improving the EDT model used in this investigation.

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