Spelling suggestions: "subject:"shelf"" "subject:"helf""
711 |
Piritização de elementos-traço em sedimentos recentes do sistema de ressurgência de Cabo Frio (Rio de Janeiro)Ramírez, Manuel Antonio Moreira 13 April 2016 (has links)
Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2016-04-13T15:18:33Z
No. of bitstreams: 1
Mestrado Manuel Moreira.pdf: 7413069 bytes, checksum: 0f15055b235c438ffd4fac6dde85f099 (MD5) / Made available in DSpace on 2016-04-13T15:18:33Z (GMT). No. of bitstreams: 1
Mestrado Manuel Moreira.pdf: 7413069 bytes, checksum: 0f15055b235c438ffd4fac6dde85f099 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geociências-Geoquímica. Niterói, RJ / Elementos-tarços são freqüentemente utilizados como indicadores das condições redox e da paleoprodutividade marinha, que podem afetar a distribuição e o fracionamento geoquímico destes elementos. O potencial efeito do ciclo re-oxidativo da pirita sedimentar sobre o grau de piritização destes indicadores (degree of trace metal pyritization – DTMP) não tem sido anteriormente avaliado. Esta avaliação foi realizada em testemunhos sedimentares da plataforma continental sob influência do Sistema de Ressurgência de Cabo Frio (RJ). A relação do DTMP com a assinatura isotópica do S na pirita (δ34S), que se torna mais leve em resposta ao ciclo re-oxidativo da pirita na área de estudo, sugere que a influência pode ser alta (para Pb, As, Cd e Mn), baixa (para Zn e Cu) ou desprezível (para Cr e Ni), dependendo do elemento considerado. Sedimentos mais antigos e ricos em pirita possibilitaram a identificação de um aparente limiar para o efeito da re-oxidação, após o qual os elementos Pb, As, Cd, Mn e Zn apresentaram maior piritização. Um testemunho em posição intermediária na plataforma apresentou correlações negativas das concentrações reativas de Mn, Cu, Ni e Pb com as concentrações de Fe na pirita, assim como outros dois testemunhos apresentaram em relação a Mn e Pb. Isto sugere um consumo de óxidos de Mn (e metais associados) em reação com a pirita, contribuindo para explicar o alto DTMP apresentado pelo Pb, que discorda das predições termodinâmicas e de cinética de incorporação deste metal pela pirita. As assinaturas isotópicas da pirita na área de estudo (que apresenta condições óxicas), foram semelhantes às de ambientes sedimentares anóxicos e euxínicos reportadas na literatura, sugerindo que o ciclo re-oxidativo pode afetar a susceptibilidade de incorporação e a preservação dos elementos na pirita em uma ampla variedade de condições sedimentares. A abordagem metodológica proposta pode subsidiar a melhor interpretação do processo de piritização e suas aplicações para a indicação de condições paleo-redox e de paleo-produtividade / Potential effects of sedimentary pyrite re-oxidative cycling on the degree of trace metals pyritization (DTMP) were evaluated in four sediment cores from the continental shelf under the influence of a tropical upwelling system (Cabo Frio, Brazil). The DTMP relation with stable isotope signals (δ34S) of chromium reducible sulfur, which became lighter in response to intense pyrite re-oxidative cycling in the study area, suggests high (Pb, As, Cd and Mn), low (Zn and Cu) or negligible (Cr and Ni) re-oxidation influences. Oldest pyrite-richer sediments provide an apparent threshold for intense pyrite re-oxidation, after which most trace elements (Pb, As, Cd, Mn and Zn) presented more accentuated DTMP. A middle shelf core presented negative correlations of reactive Mn, Cu, Ni and Pb with pyrite iron, suggesting Mn oxide (and associated metals) depletion in reaction with pyrite. This contributes to explain the observed high degree of Pb pyritization in disagreement with predictions derived from both thermodynamics and water exchange reaction kinetics. Pyrite δ34S signatures under the oxic bottom water from the study area were similar to those from euxinic sedimentary environments, suggesting that pyrite re-oxidative cycling can affect trace element susceptibility to be incorporated and preserved into pyrite in a wide range of sedimentary conditions
|
712 |
Variabilité spatio-temporelle des flux sédimentaires dans le Golfe de Gascogne : contributions relatives des forçages climatiques et des activités de chalutage / Spatio-temporal variability of sediment fluxes in the Bay of Biscay : relative contributions of climate forcings and trawling activitiesMengual, Baptiste 12 December 2016 (has links)
L'étude de la variabilité spatio-temporelle des flux sédimentaires sous l'influence des forçages naturels et des activités de chalutage a été entreprise à l'échelle du plateau continental du Golfe de Gascogne, en associant des données in situ et une modélisation numérique 3D déterministe. Deux campagnes en mer spécifiques ont été menées pour quantifier les impacts physiques induits par un chalut professionnel au niveau de la Grande-Vasière, en termes de remise en suspension (panache turbide), et de perturbation de la structure et de la nature du sédiment superficiel. Ces données ont permis d'estimer à 0.13 kg.m-2 le taux d'érosion moyen. Leur croisement avec des données d'effort de pêche a conduit à une cartographie mensuelle du flux d'érosion par chalutage. D'autre part, un modèle hydro-sédimentaire 3D réaliste a été mis en place et calibré à partir de mesures au point fixe. Une attention particulière a été accordée au paramétrage de l'érosion naturelle sous l'influence combinée des vagues et des courants. Une nouvelle formulation de la loi d'érosion adaptée aux mélanges de sable fin et de vase classiquement rencontrés sur les plateaux continentaux a été proposée et a permis d'optimiser significativement la réponse du modèle en termes de turbidité. Deux simulations de 5 ans ont été réalisées en incluant ou non l'influence du chalutage de fond, dans le but de quantifier et comparer les contributions relatives des forçages naturels et anthropique sur les flux verticaux (érosion) et horizontaux (transport solide) de sédiments. La variabilité temporelle des flux est décrite en une succession de régimes caractéristiques répondant à divers forçages (e.g. marée, vent, vagues, chalutage), et les flux résiduels saisonniers et annuels sont commentés : sans tenir compte des apports fluviaux, le flux de matériel vaseux a été estimé à 1.6 Mt/an sortant par le nord (au droit de La Pointe du Raz) et à 0.62 Mt/an vers le talus continental (au niveau de l'isobathe 180 m). / The spatio-temporal variability of sediment fluxes under the influence of natural forcings and trawling activities was assessed at the scale of the Bay of Biscay shelf, from in situ data and a 3D process-based numerical modelling. Two sea trials were carried out to quantify physical impacts induced by a professional trawling gear over an intensively trawled area of the shelf, the "Grande-Vasière", in terms of resuspension (turbid plume) and alteration of the surficial sediment nature and structure. These data enabled to estimate an average trawling-induced erosion rate of 0.13 kg.m-2. Their combination with fishing effort data led to monthly spatial distributions of trawling-induced erosion fluxes.Besides, a 3D realistic hydro-sedimentary model has been set up and calibrated from measurements acquired at a mooring station. The calibration task mainly consisted in assessing the natural erosion law setting under the influence of waves and currents. A new formulation of the erosion law has been proposed to describe the erosion of any mixture of mud and fine sand (sediment facies classically encountered on continental shelves) and led to a noteworthy improvement of the model response in terms of turbidity. Two 5-year simulations were performed accounting for natural forcings only or both natural and anthropogenic forcings in order to quantify and compare their respective contributions to sediment fluxes (vertical and horizontal sediment dynamics). The temporal variability of sediment fluxes is described in a succession of typical regimes occurring in response to various conditions of forcings (e.g. tide, wind, wave, trawling), and residual fluxes are assessed at seasonal and annual scales: without accounting for riverine sediment inputs, the mud flux is estimated to 1.6 Mt/yr outflowing northward (at the latitude of the Pointe du Raz) and to 0.62 Mt/yr toward the continental slope (through the 180 m isobath).
|
713 |
The British North Sea: The Importance Of And Factors Affecting Tax Revenue From Oil ProductionHill, Mark 10 February 2004 (has links) (PDF)
The oil industry is the richest and most influential industry in the world. The industry has moved the fates of nations. Oil is required to fight wars and exert power, and the restriction of this energy source is paramount to the restriction of movement, control, and in the end, power. Management of this resource and the tax revenue it generates are of serious strategic importance, both domestically and internationally. Understanding the results of taxation for this important commodity is important to international relations as well. The tax system affects tax revenue, government actions, oil company actions, and the oil supply itself. Each of these is important to international relations.
|
714 |
Design and Development of a CubeSat Hardware Architecture with COTS MPSoC using Radiation Mitigation TechniquesVasudevan, Siddarth January 2020 (has links)
CubeSat missions needs components that are tolerant against the radiation in space. The hardware components must be reliable, and it must not compromise the functionality on-board during the mission. At the same time, the cost of hardware and its development should not be high. Hence, this thesis discusses the design and development of a CubeSat architecture using a Commercial Off-The- Shelf (COTS) Multi-Processor System on Chip (MPSoC). The architecture employs an affordable Rad-Hard Micro-Controller Unit as a Supervisor for the MPSoC. Also, it uses several radiation mitigation techniques such as the Latch-up protection circuit to protect it against Single-Event Latch-ups (SELs), Readback scrubbing for Non- Volatile Memories (NVMs) such as NOR Flash and Configuration scrubbing for the FPGA present in the MPSoC to protect it against Single-Event Upset (SEU)s, reliable communication using Cyclic Redundancy Check (CRC) and Space packet protocol. Apart from such functionalities, the Supervisor executes tasks such as Watchdog that monitors the liveliness of the applications running in the MPSoC, data logging, performing Over-The-Air Software/Firmware update. The thesis work implements functionalities such as Communication, Readback memory scrubbing, Configuration scrubbing using SEM-IP, Watchdog, and Software/Firmware update. The execution times of the functionalities are presented for the application done in the Supervisor. As for the Configuration scrubbing that was implemented in Programmable Logic (PL)/FPGA, results of area and latency are reported. / CubeSat-uppdrag behöver komponenter som är toleranta mot strålningen i rymden. Maskinvarukomponenterna måste vara pålitliga och funktionaliteten ombord får inte äventyras under uppdraget. Samtidigt bör kostnaden för hårdvara och dess utveckling inte vara hög. Därför diskuterar denna avhandling design och utveckling av en CubeSatarkitektur med hjälp av COTS (eng. Custom-off-The-Shelf) MPSoC (eng. Multi Processor System-on-Chip). Arkitekturen använder en prisvärd strålningshärdad (eng. Rad-Hard) Micro-Controller Unit(MCU) som Övervakare för MPSoC:en och använder också flera tekniker för att begränsa strålningens effekter såsom kretser för att skydda kretsen från s.k. Single Event Latch-Ups (SELs), återläsningsskrubbning för icke-volatila minnen (eng. Non-Volatile Memories) NVMs som NOR Flash och skrubbning av konfigurationsminnet skrubbning för FPGA:er i MPSoC:en för att skydda dem mot Single-Event Upsets (SEUs), och tillhandahålla pålitlig kommunikation mha CRC och Space Packet Protocol. Bortsett från sådana funktioner utför Övervakaren uppgifter som Watchdog för att övervaka att applikationerna som körs i MPSoC:en fortfarande är vid liv, dataloggning, och Over- the-Air-uppdateringar av programvaran/Firmware. Examensarbetet implementerar funktioner såsom kommunikation, återläsningsskrubbning av minnet, konfigurationsminnesskrubbning mha SEM- IP, Watchdog och uppdatering av programvara/firmware. Exekveringstiderna för utförandet av funktionerna presenteras för den applikationen som körs i Övervakaren. När det gäller konfigurationsminnesskrubbningen som implementerats i den programmerbara logiken i FPGA:n, rapporteras area och latens.
|
715 |
Operations research models for the management of supply chains of perishable and heterogeneous products in uncertain contexts. Application to the agri-food and ceramic sectorsEsteso Álvarez, Ana 12 March 2022 (has links)
Tesis por compendio / [ES] Algunos productos se caracterizan por su falta de homogeneidad, lo que significa que productos con diferentes características pueden ser obtenidos de un mismo proceso de producción debido a factores incontrolables como la naturaleza de las materias primas o las condiciones ambientales durante la producción. Hay cuatro aspectos que caracterizan la falta de homogeneidad en el producto: los subtipos homogéneos que se obtienen de un mismo lote de producción, la cantidad de productos que componen cada subtipo, el valor de cada uno de los subtipos, y el estado de los productos.
La falta de homogeneidad en el producto dificulta la gestión de los procesos de las empresas y cadenas de suministro en el momento en el que los clientes requieren homogeneidad entre las unidades de producto que adquieren. Un ejemplo de esto se produce en el sector de la cerámica, en el que los clientes requieren que todas las unidades que van a ser ensambladas juntas tengan el mismo color, espesor y calidad por razones estéticas y de seguridad. Otro ejemplo es el extraído del sector agroalimentario, en el que el mercado final requiere productos que cumplan con un tamaño mínimo, un color particular, o sabor en el caso de las frutas. Además, el sector agroalimentario tiene la complejidad añadida producida por el deterioro de los productos a lo largo del tiempo, y la necesidad de los mercados de ofrecer a los clientes productos con una mínima duración tras su venta.
En esta Tesis, se define como productos heterogéneos a aquellos productos que se pueden clasificar en subtipos homogéneos con una cantidad variable, mientras que los productos perecederos son aquellos que, además de ser heterogéneos, tienen falta de homogeneidad en su estado. De acuerdo con estos conceptos, el sector cerámico comercializa productos heterogéneos mientras que el sector agroalimentario comercializa productos perecederos.
Esta Tesis propone marcos conceptuales y modelos de Investigación Operativa que soporten la gestión de cadenas de suministro con productos heterogéneos y perecederos en la toma de decisiones centralizada y distribuidas relacionadas con los niveles de decisión estratégica, táctica y operativa. El objetivo es mejorar la competitividad, sostenibilidad y flexibilidad de la cadena de suministro para adaptarse a los requerimientos del mercado bajo condiciones de incertidumbre. Para esto, se han propuesto modelos de Investigación Operativa deterministas e inciertos, cuyos resultados se comparan concluyendo que los resultados obtenidos con los modelos inciertos se adaptan mejor al comportamiento real de las cadenas de suministros.Los modelos de Investigación Operativa propuestos han contribuido a tres áreas de investigación: problemas operativos en el sector cerámico, problemas estratégicos en el sector agroalimentario y problemas de planificación en el sector agroalimentario.
Las principales novedades en los problemas operativos en el sector cerámico son el modelado de las características de las baldosas cerámicas, la consideración de los requerimientos de homogeneidad entre unidades de diferentes líneas de pedido, y la posibilidad de realizar entregas parciales y entregas con retraso.
Esta Tesis contribuye a los problemas estratégicos en el sector agroalimentario al diseñar una cadena de suministro completa de productos agroalimentarios frescos considerando el aspecto perecedero de los productos e integrando decisiones tácticas, y determinando el impacto real que tiene considerar el aspecto perecedero de los productos durante el diseño de la cadena de suministro ... / [CA] Alguns productes es caracteritzen per la seua falta d'homogeneïtat, el que significa que productes amb diferents característiques poden ser obtinguts d'un mateix procés de producció degut a factors incontrolables com la naturalesa de les matèries primeres o les condicions ambientals durant la producció. Hi ha quatre aspectes que caracteritzen la falta d'homogeneïtat en el producte: els subtipus homogenis que s'obtenen d'un mateix lot de producció, la quantitat de productes que componen cada subtipus, el valor de cada un dels subtipus, i l'estat dels productes.
La falta d'homogeneïtat en el producte dificulta la gestió dels processos de les empreses i cadenes de subministrament en el moment en què els clients requerixen homogeneïtat entre les unitats de producte que adquirixen. Un exemple d'açò es produïx en el sector de la ceràmica, en el que els clients requerixen que totes les unitats que seran acoblades juntes tinguen el mateix color, grossària i qualitat per raons estètiques i de seguretat. Un altre exemple és l'extret del sector agroalimentari, en el que el mercat final requerix productes que complisquen amb una grandària mínima, un color particular, o sabor en el cas de les fruites. A més, el sector agroalimentari té la complexitat afegida produïda pel deteriorament dels productes al llarg del temps, i la necessitat dels mercats d'oferir als clients productes amb una mínima duració després de la seua venda.
En aquesta Tesi, es definix com a productes heterogenis a aquells productes que es poden classificar en subtipus homogenis amb una quantitat variable, mentres que els productes peribles són aquells que, a més de ser heterogenis, tenen falta d'homogeneïtat en el seu estat. D'acord amb aquests conceptes, el sector ceràmic comercialitza productes heterogenis mentres que el sector agroalimentari comercialitza productes peribles.
Aquesta Tesi proposa marcs conceptuals i models d'Investigació Operativa que suporten la gestió de cadenes de subministrament amb productes heterogenis i peribles en la presa de decisions centralitzada i distribuïdes relacionades amb els nivells de decisió estratègica, tàctica i operativa. L'objectiu és millorar la competitivitat, sostenibilitat i flexibilitat de la cadena de subministrament per adaptar-se als requeriments del mercat sota condicions d'incertesa. Per a açò, s'han proposat models d'Investigació Operativa deterministes i incerts, els resultats es comparen concloent que els resultats obtinguts amb els models incerts s'adapten millor al comportament real de les cadenes de subministraments.
Els models d'Investigació Operativa proposats han contribuït a tres àrees d'investigació: problemes operatius en el sector ceràmic, problemes estratègics en el sector agroalimentari i problemes de planificació en el sector agroalimentari.
Les principals novetats en els problemes operatius en el sector ceràmic són el modelatge de les característiques de les rajoles ceràmiques, la consideració dels requeriments d'homogeneïtat entre unitats de diferents línies de comanda, i la possibilitat de realitzar lliuraments parcials i lliuraments amb retard.
Aquesta Tesi contribueix als problemes estratègics en el sector agroalimentari al dissenyar una cadena de subministrament completa de productes agroalimentaris frescos considerant l'aspecte perible dels productes, integrant decisions tàctiques, i determinant l'impacte real que té considerar l'aspecte perible dels productes durant el disseny de la cadena de subministrament ... / [EN] Some products are characterised by their lack of homogeneity, what means that products with different characteristics can be obtained from the same production process due to uncontrollable factors such as the nature of raw materials or the environmental conditions during production. There are four aspects that characterize the lack of homogeneity in the product: the homogeneous subtypes to be obtained from a production lot, the quantity of products that belong to each subtype, the value related to each of the subtypes and the state of the products.
The lack of homogeneity in the product hinders the management of the supply chain or company's processes at the time customers require the homogeneity among the acquired units of product. An example of this is produced in the ceramic tile sector, in which customers need all acquired ceramic tiles that are going to be jointly assembled to have the same colour, thickness and quality for aesthetic and safety reasons. Another example is the extracted from the agri-food sector, in which final markets require products that meet some characteristics such as a minimum size, a particular colour or flavour in the case of fruits. In addition, the agri-food sector has the added complexity produced by the deterioration of products over time, and the need of markets to offer to end consumers products with a minimum durability after sale.
In this Thesis, heterogeneous products are defined as products for which different subtypes can be obtained in a variable quantity while perishable products are those that, apart from being heterogeneous, have a lack of homogeneity in their state. According to these concepts, ceramic sectors would commercialize heterogeneous products while the agri-food sector would do so with perishable products.
This Thesis proposes conceptual frameworks and Operations Research models to support the management of supply chains with heterogeneous and perishable products in centralized and distributed decision-making processes related to strategic, tactical and operative decisional levels. The objective is to improve the supply chain competitiveness, sustainability and flexibility to adapt to market requirements under uncertain conditions. For this, both deterministic and uncertain Operations Research models have been proposed, whose results are compared concluding that results obtained with uncertain models better fit with the behaviour of real supply chains.
The proposed Operations Research models have contributed to three research areas: operational problems in the ceramic sector, strategic problems in the agri-food sector and planning problems in the agri-food sector.
Main novelties in the ceramic operational problems are the modelling of the characteristics of ceramic tile products, the consideration of homogeneity requirements between units from different order lines, and the possibility of making partial deliveries and delayed deliveries.
This Thesis contributes to strategic problems in agri-food products by designing an entire fresh agri-food supply chain considering the perishability of products and integrating tactical decisions, and by determining the real impact that considering the products' perishability has on the supply chain design process ... / This Thesis has been developed in the Research Centre of Management and Production
Engineering (CIGIP, for its acronym in Spanish “Centro de Investigación en Gestión e
Ingeniería de Producción”) of the Universitat Politècnica de València with the support of
the predoctoral grant Programme of Formation of University Professors (FPU, for its
acronym in Spanish “Formación de Profesorado Universitario”) from the Spanish
Ministry of Science, Innovation and Universities (Ref. FPU15/03595). The supervisors
of this Thesis are Dr. Angel Ortiz, and Dra. María del Mar Alemany Diaz that are
Professors in the Research Centre of Management and Production Engineering (CIGIP)
of the Universitat Politècnica de València. The FPU grant has been endorsed by the
supervisor Dr. Ángel Ortiz.
This Thesis has also been supported by the project ‘RUC-APS: Enhancing and
implementing Knowledge based ICT solutions within high Risk and Uncertain
Conditions for Agriculture Production Systems’ (Ref. 691249) funded by the EU under
its funding scheme H2020-MSCA-RISE-2015, the project ‘Methods and models for operations planning and order management in supply chains characterised by uncertainty
in production due to the lack of product uniformity’ (PLANGES-FHP) (Ref. DPI2011-
23597) funded by the Spanish Ministry of Economy and Competitiveness. The projects
RUC-APS and PLANGES-FHP have been led by the one of the supervisors of this Thesis
Dr. María del Mar Eva Alemany.
In order to obtain the international mention for this Thesis, three months of research
stages have been made in the research agency Agenzia Lucana di Sviluppo e di
Innovazione in Agricoltora, located in Metaponto (Italy) / Esteso Álvarez, A. (2020). Operations research models for the management of supply chains of perishable and heterogeneous products in uncertain contexts. Application to the agri-food and ceramic sectors [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/141099 / Compendio
|
716 |
Untersuchungen zu Topographie und Bewegungsverhalten für das Küstengebiet des Riiser-Larsen- und Brunt-Schelfeises mittels Radarfernerkundung / Investigations of surface topography and ice dynamics for the coastal areas of the Riiser-Larsen and Brunt ice shelf based on radar remote sensingBäßler, Michael 11 July 2011 (has links) (PDF)
Mit der Weiterentwicklung von Sensoren und Methoden hat die Satellitenfernerkundung innerhalb der letzten 20 Jahre nicht nur einen großen Stellenwert in der Polarforschung errungen, sondern vor allem die Herangehensweisen an eine Vielzahl glaziologischer Probleme grundlegend verändert. RADAR-Sensoren (Radio Detection and Ranging) sind dabei besonders bei der Erkundung vereister Regionen hilfreich und tragen stark zur Ableitung klimasensitiver Parameter im Bereich der Antarktis bei.
Nach einem einführenden Überblick im ersten wird im zweiten Kapitel mit Darstellungen zur Nutzung von RADAR-Messungen für Fernerkundungszwecke begonnen. Die zur Erhöhung der räumlichen Auflösung verwendete SAR-Prozessierung (Synthetic Aperture Radar) wird daraufhin kurz umrissen, bevor zu den Grundlagen der interferometrischen Auswertung (InSAR) übergeleitet wird. Bei dieser werden Phasendifferenzen unterschiedlicher Aufnahmen für Messzwecke eingesetzt. In den Beschreibungen wird aufgezeigt, wie sich derartige Messungen für die Ermittlung von Oberflächentopographie und Fließverhalten in polaren Regionen nutzen lassen. Eine Darstellung der ebenfalls benötigten Methoden zur Bestimmung von Verschiebungen in Bildpaaren und das Messprinzip der Laseraltimetrie beenden diesen Theorieteil.
Das dritte Kapitel der Arbeit ist der Vorstellung des Arbeitsgebietes und der genutzten Datensätze gewidmet. Nach der geographischen Einordnung des Untersuchungsgebietes werden die wichtigsten glaziologischen Gegebenheiten vorgestellt. In der sich anschließenden Beschreibung genutzter Datensätze werden vor allem die für diese Region verfügbaren Höhen- und Ozeangezeitenmodelle intensiver besprochen.
Die Bestimmung der Oberflächentopographie durch differentielle SAR-Interferometrie (DInSAR) ist Thema des vierten Kapitels. Nachdem die nötigen technischen Aspekte des Prozessierungsablaufes knapp erläutert wurden, werden die Unterschiede bei der Doppeldifferenzbildung benachbarter und identischer Wiederholspuren herausgearbeitet. Danach wird am Beispiel gezeigt, wie mithilfe von ICESat-Daten (Ice, Cloud and Land Elevation Satellite) eine Basislinienverbesserung zur genaueren Höhenbestimmung durchgeführt werden kann. Die ursprünglich separat abgeleiteten Höhenmodelle werden dann zu einer gemeinsamen Lösung kombiniert, welche abschließend hinsichtlich ihrer Genauigkeit besprochen und anderen Modellen vergleichend gegenübergestellt wird.
Die Ableitung von Fließgeschwindigkeiten mit dem Hintergrund einer späteren Berechnung von Massenflüssen ist Gegenstand des fünften Kapitels, wobei drei unterschiedliche Methoden genutzt werden. Im ersten Fall wird das für RADAR-Bilder typische, hochfrequente Rauschen zur Bestimmung von Verschiebungen in ALOS-Daten (Advanced Land Observing Satellite) genutzt.
Mit dieser Methode können durchgehende Fließgeschwindigkeitsfelder vom aufliegenden Bereich über die Aufsetzzone bis auf das Schelfeis ermittelt werden. DesWeiteren werden aus ERS-Daten (European Remote Sensing Satellite), die über einen Zeitraum von reichlich 13 Jahren vorliegen, Verschiebungen durch die Verfolgung von unveränderten, aber sich bewegenden Eisstrukturen bestimmt. Bei der als Drittes angewendeten, interferometrischen Methode werden aufsteigende und absteigende Satellitenspuren kombiniert, um die Fließinformationen zu rekonstruieren. In den jeweiligen Sektionen wird neben der Vorstellung der Ergebnisse auch deren Genauigkeit diskutiert.
Das letzte große, sechste Kapitel untergliedert sich in zwei Teile. Im ersten dieser beiden Abschnitte wird gezeigt, wie InSAR und DInSAR zur Lagekartierung der Aufsetzzone eingesetzt werden können. Dabei werden die auf diese Weise ermittelten Ergebnisse dargestellt und diskutiert. Im zweiten, umfangreicheren Teil werden die zuvor gewonnenen Höhen- und Geschwindigkeitsinformationen genutzt, um deren Einfluss aus den InSAR-Messungen zu eliminieren, wodurch vertikale Höhenunterschiede mittels InSAR bestimmt werden können. Dies ist besonders für den Bereich der Aufsetzzone und des Schelfeises von Interesse, da diese Areale teilweise oder vollständig von Ozeangezeiten beeinflusst werden. Nach einer Luftdruckkorrektion werden den ermittelten Höhenunterschieden (entlang selektierter Profile) die Prädiktionen zwölf verfügbarer Ozeangezeitenmodelle gegenübergestellt. Die RMS-Werte dieser Differenzen werden abschließend genutzt, um die Qualität der Ozeangezeitenmodelle für die Region des Arbeitsgebietes einzustufen.
Zum Abschluss werden in einer Zusammenfassung noch einmal die wichtigsten Ergebnisse aller Kapitel resümiert und bewertet. / The development of new satellite sensors within the last 20 years along with changes towards more sophisticated processing strategies has not only given a new impetus to remote sensing data in view of polar research but also changed how a variety of glaciological problems are being addressed today. Particularly RADAR (radio detection and ranging) sensors are well-suited for the observation of glaciated areas and have already helped to retrieve a vast amount of climate sensitive parameters from the area of Antarctica.
After an introductive overview at the beginning, the second chapter continues with the description of how RADAR measurements can be used to generate remote sensing images. The principle of synthetic aperture RADAR (SAR) which allows a better focusing of the RADAR
measurements and therewith a rigorous increase of the spatial resolution of the images is outlined generally before more precise descriptions explain how interferometric SAR (InSAR) analyses can be used for the determination of surface topography heights and area-wide flow velocities.
Two other techniques, namely matching methods for the determination of shifts between two images as well as the laser satellite altimetry are explained at the end of this chapter which closes the theoretical basics.
The next section introduces the area of interest along with data sets which were used for validation purposes. After a careful exposure of the geographical situation, single objects such as ice streams and ice shelves are described in more detail. The following part, the data set introduction, has besides the description of other measurements its focus on topography and ocean tide models which are available for the area of investigation.
Chapter four deals with the estimation of surface topography heights from differential InSAR (DInSAR) analyses. Therein the major differences for the usage of similar repeat tracks in contrast to neighboring, overlapping tracks will be shown and thoroughly discussed. The example of one track will be used to demonstrate how the required baseline estimation can be achieved if ICESat (Ice, Cloud and Land Elevation Satellite) profiles are used as tie points. Afterwards, all separately derived height models will be combined to obtain one final solution followed by an error analysis. A comparison to other available elevation models visualizes the spatial resolution of the derived model.
The utilization of three different methods for the estimation of surface flow velocities (with the background of possible mass flux determinations) is the topic of the fifth chapter. The first case describes the usage of the high frequent noise contained in RADAR images for the tracking of horizontal surface displacements. Based on ALOS (Advanced Land Observing Satellite) data a flow velocity field which extends from the interior of the ice sheet across the grounding zone up to the ice shelf will be presented. Secondly, geocoded ERS (European Remote Sensing Satellite) images covering a time span of more than 13 years are used to track the motions of well-structured flat areas (ice shelf and glacier tongue). In the third approach used descending and ascending satellite passes will be combined in conjunction with a surface parallel flow assumption to interferometrically derive flow velocities in grounded areas. In each section respective errors will be discussed in order to evaluate the accuracy of the performed measurements.
The last bigger chapter, number six, is divided into two sections. In the first one the adoption of SAR and InSAR with respect to the mapping of the grounding line location will be demonstrated.
Results of the entire working area will be presented and compared to other data. The second section deploys the results of topography heights and flow velocities to remove both effects from the InSAR measurements which then allows to also measure height changes. This is of particular interest for the floating areas of ice shelf which are fully affected by ocean tides as well as for the grounding zone locations which partially experience deformations due to these height changes.
After the correction for air pressure, changes between the image acquisitions, height changes along selected profiles are compared to twelve different ocean tide models. The RMS values of the differences are then used to evaluate the quality of these models for the working area.
The most important results and conclusions are summarized in the last chapter.
|
717 |
Untersuchungen zu Topographie und Bewegungsverhalten für das Küstengebiet des Riiser-Larsen- und Brunt-Schelfeises mittels Radarfernerkundung: Untersuchungen zu Topographie und Bewegungsverhalten für das Küstengebiet des Riiser-Larsen- und Brunt-Schelfeises mittels RadarfernerkundungBäßler, Michael 28 April 2011 (has links)
Mit der Weiterentwicklung von Sensoren und Methoden hat die Satellitenfernerkundung innerhalb der letzten 20 Jahre nicht nur einen großen Stellenwert in der Polarforschung errungen, sondern vor allem die Herangehensweisen an eine Vielzahl glaziologischer Probleme grundlegend verändert. RADAR-Sensoren (Radio Detection and Ranging) sind dabei besonders bei der Erkundung vereister Regionen hilfreich und tragen stark zur Ableitung klimasensitiver Parameter im Bereich der Antarktis bei.
Nach einem einführenden Überblick im ersten wird im zweiten Kapitel mit Darstellungen zur Nutzung von RADAR-Messungen für Fernerkundungszwecke begonnen. Die zur Erhöhung der räumlichen Auflösung verwendete SAR-Prozessierung (Synthetic Aperture Radar) wird daraufhin kurz umrissen, bevor zu den Grundlagen der interferometrischen Auswertung (InSAR) übergeleitet wird. Bei dieser werden Phasendifferenzen unterschiedlicher Aufnahmen für Messzwecke eingesetzt. In den Beschreibungen wird aufgezeigt, wie sich derartige Messungen für die Ermittlung von Oberflächentopographie und Fließverhalten in polaren Regionen nutzen lassen. Eine Darstellung der ebenfalls benötigten Methoden zur Bestimmung von Verschiebungen in Bildpaaren und das Messprinzip der Laseraltimetrie beenden diesen Theorieteil.
Das dritte Kapitel der Arbeit ist der Vorstellung des Arbeitsgebietes und der genutzten Datensätze gewidmet. Nach der geographischen Einordnung des Untersuchungsgebietes werden die wichtigsten glaziologischen Gegebenheiten vorgestellt. In der sich anschließenden Beschreibung genutzter Datensätze werden vor allem die für diese Region verfügbaren Höhen- und Ozeangezeitenmodelle intensiver besprochen.
Die Bestimmung der Oberflächentopographie durch differentielle SAR-Interferometrie (DInSAR) ist Thema des vierten Kapitels. Nachdem die nötigen technischen Aspekte des Prozessierungsablaufes knapp erläutert wurden, werden die Unterschiede bei der Doppeldifferenzbildung benachbarter und identischer Wiederholspuren herausgearbeitet. Danach wird am Beispiel gezeigt, wie mithilfe von ICESat-Daten (Ice, Cloud and Land Elevation Satellite) eine Basislinienverbesserung zur genaueren Höhenbestimmung durchgeführt werden kann. Die ursprünglich separat abgeleiteten Höhenmodelle werden dann zu einer gemeinsamen Lösung kombiniert, welche abschließend hinsichtlich ihrer Genauigkeit besprochen und anderen Modellen vergleichend gegenübergestellt wird.
Die Ableitung von Fließgeschwindigkeiten mit dem Hintergrund einer späteren Berechnung von Massenflüssen ist Gegenstand des fünften Kapitels, wobei drei unterschiedliche Methoden genutzt werden. Im ersten Fall wird das für RADAR-Bilder typische, hochfrequente Rauschen zur Bestimmung von Verschiebungen in ALOS-Daten (Advanced Land Observing Satellite) genutzt.
Mit dieser Methode können durchgehende Fließgeschwindigkeitsfelder vom aufliegenden Bereich über die Aufsetzzone bis auf das Schelfeis ermittelt werden. DesWeiteren werden aus ERS-Daten (European Remote Sensing Satellite), die über einen Zeitraum von reichlich 13 Jahren vorliegen, Verschiebungen durch die Verfolgung von unveränderten, aber sich bewegenden Eisstrukturen bestimmt. Bei der als Drittes angewendeten, interferometrischen Methode werden aufsteigende und absteigende Satellitenspuren kombiniert, um die Fließinformationen zu rekonstruieren. In den jeweiligen Sektionen wird neben der Vorstellung der Ergebnisse auch deren Genauigkeit diskutiert.
Das letzte große, sechste Kapitel untergliedert sich in zwei Teile. Im ersten dieser beiden Abschnitte wird gezeigt, wie InSAR und DInSAR zur Lagekartierung der Aufsetzzone eingesetzt werden können. Dabei werden die auf diese Weise ermittelten Ergebnisse dargestellt und diskutiert. Im zweiten, umfangreicheren Teil werden die zuvor gewonnenen Höhen- und Geschwindigkeitsinformationen genutzt, um deren Einfluss aus den InSAR-Messungen zu eliminieren, wodurch vertikale Höhenunterschiede mittels InSAR bestimmt werden können. Dies ist besonders für den Bereich der Aufsetzzone und des Schelfeises von Interesse, da diese Areale teilweise oder vollständig von Ozeangezeiten beeinflusst werden. Nach einer Luftdruckkorrektion werden den ermittelten Höhenunterschieden (entlang selektierter Profile) die Prädiktionen zwölf verfügbarer Ozeangezeitenmodelle gegenübergestellt. Die RMS-Werte dieser Differenzen werden abschließend genutzt, um die Qualität der Ozeangezeitenmodelle für die Region des Arbeitsgebietes einzustufen.
Zum Abschluss werden in einer Zusammenfassung noch einmal die wichtigsten Ergebnisse aller Kapitel resümiert und bewertet. / The development of new satellite sensors within the last 20 years along with changes towards more sophisticated processing strategies has not only given a new impetus to remote sensing data in view of polar research but also changed how a variety of glaciological problems are being addressed today. Particularly RADAR (radio detection and ranging) sensors are well-suited for the observation of glaciated areas and have already helped to retrieve a vast amount of climate sensitive parameters from the area of Antarctica.
After an introductive overview at the beginning, the second chapter continues with the description of how RADAR measurements can be used to generate remote sensing images. The principle of synthetic aperture RADAR (SAR) which allows a better focusing of the RADAR
measurements and therewith a rigorous increase of the spatial resolution of the images is outlined generally before more precise descriptions explain how interferometric SAR (InSAR) analyses can be used for the determination of surface topography heights and area-wide flow velocities.
Two other techniques, namely matching methods for the determination of shifts between two images as well as the laser satellite altimetry are explained at the end of this chapter which closes the theoretical basics.
The next section introduces the area of interest along with data sets which were used for validation purposes. After a careful exposure of the geographical situation, single objects such as ice streams and ice shelves are described in more detail. The following part, the data set introduction, has besides the description of other measurements its focus on topography and ocean tide models which are available for the area of investigation.
Chapter four deals with the estimation of surface topography heights from differential InSAR (DInSAR) analyses. Therein the major differences for the usage of similar repeat tracks in contrast to neighboring, overlapping tracks will be shown and thoroughly discussed. The example of one track will be used to demonstrate how the required baseline estimation can be achieved if ICESat (Ice, Cloud and Land Elevation Satellite) profiles are used as tie points. Afterwards, all separately derived height models will be combined to obtain one final solution followed by an error analysis. A comparison to other available elevation models visualizes the spatial resolution of the derived model.
The utilization of three different methods for the estimation of surface flow velocities (with the background of possible mass flux determinations) is the topic of the fifth chapter. The first case describes the usage of the high frequent noise contained in RADAR images for the tracking of horizontal surface displacements. Based on ALOS (Advanced Land Observing Satellite) data a flow velocity field which extends from the interior of the ice sheet across the grounding zone up to the ice shelf will be presented. Secondly, geocoded ERS (European Remote Sensing Satellite) images covering a time span of more than 13 years are used to track the motions of well-structured flat areas (ice shelf and glacier tongue). In the third approach used descending and ascending satellite passes will be combined in conjunction with a surface parallel flow assumption to interferometrically derive flow velocities in grounded areas. In each section respective errors will be discussed in order to evaluate the accuracy of the performed measurements.
The last bigger chapter, number six, is divided into two sections. In the first one the adoption of SAR and InSAR with respect to the mapping of the grounding line location will be demonstrated.
Results of the entire working area will be presented and compared to other data. The second section deploys the results of topography heights and flow velocities to remove both effects from the InSAR measurements which then allows to also measure height changes. This is of particular interest for the floating areas of ice shelf which are fully affected by ocean tides as well as for the grounding zone locations which partially experience deformations due to these height changes.
After the correction for air pressure, changes between the image acquisitions, height changes along selected profiles are compared to twelve different ocean tide models. The RMS values of the differences are then used to evaluate the quality of these models for the working area.
The most important results and conclusions are summarized in the last chapter.
|
718 |
Double dating detrital zircons in till from the Ross Embayment, AntarcticaWelke, Bethany Marie 21 May 2014 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / U/Pb and (U-Th)/He (ZHe) dating of detrital zircons from glacial till samples in the Ross Embayment, Antarctica records cooling after the Ross/Pan-African orogeny (450-625 Ma) followed by a mid-Jurassic to mid-Cretaceous heating event in the Beacon basin. Zircons were extracted from till samples from heads of major outlet glaciers in East Antarctica, one sample at the mouth of Scott Glacier, and from beneath three West Antarctic ice streams. The Ross/Pan-African U/Pb population is ubiquitous in these Antarctic tills and many Beacon Supergroup sandstones, thus 83 grains were analyzed for ZHe to subdivide this population. Two ZHe age populations are evident in East Antarctic tills, with 64% of grains 115-200 Ma and 35% between 200-650 Ma. The older population is interpreted to be associated with the Ross/Pan-African orogeny including cooling of the Granite Harbour Intrusives and/or exhumation of the older basement rocks to form the Kukri Peneplain. The lag time between zircon U/Pb, ZHe and 40Ar/39Ar ages from K-bearing minerals show cooling over 200 My. Grains in East Antarctic tills with a ZHe age of 115-200 Ma likely reflects regional heating following the breakup of Gondwana from the Ferrar dolerite intrusions, subsidence within the rift basin, and a higher geothermal gradient. Subsequent cooling and/or exhumation of the Transantarctic Mountains brought grains below the closure temperature over a span of 80 My. This population may also provide a Beacon Supergroup signature as most of the tills with this age are adjacent to nunataks mapped as Beacon Supergroup and contain an abundance of
vi
Beacon pebbles within the moraine. Nine zircons grains from three Beacon Supergroup sandstones collected from moraines across the Transantarctic Mountains yield ages from 125-180 Ma. West Antarctic tills contain a range of ZHe ages from 75-450 Ma reflecting the diverse provenance of basin fill from East Antarctica and Marie Byrd Land. ZHe and U/Pb ages <105 Ma appear to be distinctive of West Antarctic tills. The combination of U/Pb, ZHe and 40Ar/39Ar analyses demonstrates that these techniques can be used to better constrain the tectonic evolution and cooling of the inaccessible subglacial source terrains beneath the Antarctic Ice Sheet.
|
Page generated in 0.0878 seconds