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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.
31

5G Positioning using Machine Learning

Malmström, Magnus January 2018 (has links)
Positioning is recognized as an important feature of fifth generation (\abbrFiveG) cellular networks due to the massive number of commercial use cases that would benefit from access to position information. Radio based positioning has always been a challenging task in urban canyons where buildings block and reflect the radio signal, causing multipath propagation and non-line-of-sight (NLOS) signal conditions. One approach to handle NLOS is to use data-driven methods such as machine learning algorithms on beam-based data, where a training data set with positioned measurements are used to train a model that transforms measurements to position estimates.  The work is based on position and radio measurement data from a 5G testbed. The transmission point (TP) in the testbed has an antenna that have beams in both horizontal and vertical layers. The measurements are the beam reference signal received power (BRSRP) from the beams and the direction of departure (DOD) from the set of beams with the highest received signal strength (RSS). For modelling of the relation between measurements and positions, two non-linear models has been considered, these are neural network and random forest models. These non-linear models will be referred to as machine learning algorithms.  The machine learning algorithms are able to position the user equipment (UE) in NLOS regions with a horizontal positioning error of less than 10 meters in 80 percent of the test cases. The results also show that it is essential to combine information from beams from the different vertical antenna layers to be able to perform positioning with high accuracy during NLOS conditions. Further, the tests show that the data must be separated into line-of-sight (LOS) and NLOS data before the training of the machine learning algorithms to achieve good positioning performance under both LOS and NLOS conditions. Therefore, a generalized likelihood ratio test (GLRT) to classify data originating from LOS or NLOS conditions, has been developed. The probability of detection of the algorithms is about 90\% when the probability of false alarm is only 5%.  To boost the position accuracy of from the machine learning algorithms, a Kalman filter have been developed with the output from the machine learning algorithms as input. Results show that this can improve the position accuracy in NLOS scenarios significantly. / Radiobasserad positionering av användarenheter är en viktig applikation i femte generationens (5G) radionätverk, som mycket tid och pengar läggs på för att utveckla och förbättra. Ett exempel på tillämpningsområde är positionering av nödsamtal, där ska användarenheten kunna positioneras med en noggrannhet på ett tiotal meter. Radio basserad positionering har alltid varit utmanande i stadsmiljöer där höga hus skymmer och reflekterar signalen mellan användarenheten och basstationen. En ide att positionera i dessa utmanande stadsmiljöer är att använda datadrivna modeller tränade av algoritmer baserat på positionerat testdata – så kallade maskininlärningsalgoritmer. I detta arbete har två icke-linjära modeller - neurala nätverk och random forest – bli implementerade och utvärderade för positionering av användarenheter där signalen från basstationen är skymd.% Dessa modeller refereras som maskininlärningsalgoritmer. Utvärderingen har gjorts på data insamlad av Ericsson från ett 5G-prototypnätverk lokaliserat i Kista, Stockholm. Antennen i den basstation som används har 48 lober vilka ligger i fem olika vertikala lager. Insignal och målvärdena till maskininlärningsalgoritmerna är signals styrkan för varje stråle (BRSRP), respektive givna GPS-positioner för användarenheten. Resultatet visar att med dessa maskininlärningsalgoritmer positioneras användarenheten med en osäkerhet mindre än tio meter i 80 procent av försöksfallen. För att kunna uppnå dessa resultat är viktigt att kunna detektera om signalen mellan användarenheten och basstationen är skymd eller ej. För att göra det har ett statistiskt test blivit implementerat. Detektionssannolikhet för testet är över 90 procent, samtidigt som sannolikhet att få falskt alarm endast är ett fåtal procent.\newline \newline%För att minska osäkerheten i positioneringen har undersökningar gjorts där utsignalen från maskininlärningsalgoritmerna filtreras med ett Kalman-filter. Resultat från dessa undersökningar visar att Kalman-filtret kan förbättra presitionen för positioneringen märkvärt.
32

Lipídios como indicadores de processos biogeoquímicos em sedimentos da margem continental do Estado do Rio de Janeiro / Lipids as biogeochemical process indicators in sediments of the continental margin of Rio de Janeiro State

Lívia Gebara Muraro Serrate Cordeiro 03 October 2011 (has links)
Este estudo constitui parte do Projeto Habitats Heterogeneidade Ambiental da Bacia de Campos coordenado pelo CENPES/Petrobras, um projeto multidisciplinar de caracterização ambiental que considera as diferentes feições e habitats da margem continental do sudeste brasileiro. O objetivo desta tese foi investigar os processos relacionados com a origem, o transporte e o acúmulo de matéria orgânica (MO) em sedimentos da margem continental da Bacia de Campos (RJ). Para isso, foram determinados a composição elementar da matéria orgânica (carbono e nitrogênio) por combustão a seco e os lipídios (esteróis, álcoois e ácidos graxos) por CG-MS e CG-DIC. Foram analisadas 215 amostras de sedimento superficial (0-2 cm de profundidade), coletadas em duas amostragens (períodos seco e chuvoso de 2008/2009), distribuídas sobre 12 isóbatas (de 25 a 3000 m) ao longo de 9 transectos de norte a sul da bacia. Além disto, foram ainda consideradas as isóbatas de 400 a 1900 m em dois cânions submarinos no norte da bacia (Almirante Câmara e Grussaí). Com base nos resultados obtidos, a MO sedimentar na plataforma e talude da bacia revelou-se essencialmente autóctone, derivada de produtores primários e secundários. Com isto, a MO contém uma fração reativa significativa e, portanto, é potencialmente biodisponível para os organismos bentônicos. No entanto, foram observados gradientes espaciais significativos na qualidade e na quantidade da MO sedimentar. Na plataforma continental (25 m a 150 m de profundidade) as concentrações de lipídios foram intermediárias e houve predomínio de MO sedimentar lábil. Exceções foram as áreas influenciadas por ressurgência costeira e/ou intrusão sub-superficial (próximo à Cabo Frio, Cabo de São Tomé e no limite norte da bacia), onde as concentrações foram altas. No talude superior e médio (400 a 1300 m) as concentrações de MO foram notadamente mais elevadas, mas com maior influência de processos bacterianos de alteração de sua composição original. E no talude inferior (1900 a 3000 m) as concentrações de MO estiveram muito baixas e apenas os lipídios mais resistentes à degradação bacteriana foram encontrados em concentrações mensuráveis. Isto sugeriu a exportação de materiais da plataforma ao longo do gradiente batimétrico, possivelmente decorrente da ação de meandros e vórtices da Corrente do Brasil e das correntes de fundo atuantes na região. Além disto, por ser lábil e biodisponível, a MO no sedimento apresenta uma fração biodisponível que pode ter uma influência na ecologia das comunidades bentônicas, particularmente aquelas localizadas no talude superior. Os cânions Grussaí e Almirante Câmara se revelaram regiões de acúmulo de MO e importantes no transporte da MO com valor nutritivo para comunidades bentônicas do talude médio e inferior. / This study is part of the Habitats Project - Campos Basin Environmental Heterogeneity - coordinated by CENPES/PETROBRAS, a multidisciplinary project that considers environmental characterization of the different features and habitats of the Brazilian South-Eastern continental margin. The aim of this thesis was to investigate the processes related to the origin, transport and accumulation of organic matter (OM) in sediments of the continental margin of the Campos Basin (RJ).To this end, the elemental composition of organic matter (carbon and nitrogen) - determined by dry combustion - and lipids (sterols, alcohols and fatty acids) - determined by GCMS and GC-FID - were considered. It was analyzed 215 samples of surface sediment (0-2 cm depth) collected in two samplings (dry and rainy seasons of 2008/2009), distributed over 12 isobaths (25 to 3000 m) along transects distributed from north to south of the basin. Moreover, it was also considered samples from the 400 to 1900 m isobaths in two submarine canyons (Almirante Câmara and Grussaí) in the northern basin. Based on the results, the sedimentary OM continental shelf and slope of Campos Basin was considered to be essentially autochthonous, derived from primary and secondary producers. As a consequence, a significant fraction of OM is reactive and therefore is potentially bioavailable to benthic organisms. However, significant spatial gradients in the quality and quantity of sedimentary OM were observed. In the continental shelf (25 m to 150 m depths), concentrations of lipids were intermediate and there was a predominance of labile sedimentary OM. Exceptions to this general feature were the areas influenced by coastal upwelling and/or sub-surface water intrusion (near Cabo Frio, Cabo de São Tomé and the northern boundary of the basin), where high concentrations of both total organic carbon and lipids were measured. In the upper and middle slope (400 to 1300 m) concentrations of OM were notably higher, but with greater influence of bacterial processes changing their original composition. And in the lower slope (1900 to 3000 m) concentrations of OM were very low and only the lipids more resistant to bacterial degradation were found in measurable concentrations. This suggested the export of materials from the continental shelf along the depth gradient, possibly due to the action of eddies and meanders of the Brazil Current and bottom currents operating in the region. Moreover, for its lability and bioavailability, the OM in the sediment can have a major influence on the ecology of benthic communities, particularly those located on the upper slope. The Almirante Câmara and Grussaí canyons revealed to be regions of OM accumulation and important features on the transport of OM with nutritional value for benthic communities of middle and lower slope.
33

Habitats coralliens dans les canyons sous-marins du Golfe de Gascogne : distribution, écologie et vulnérabilité / Coral habitats in submarine canyons of the Bay of Biscay : distribution, ecology and vulnerability

Van den Beld, Inge 20 February 2017 (has links)
Les habitats de coraux d’eau froide formés par des scléractiniaires coloniaux, des gorgones, des antipathaires et des pennatules sont des hotspots de biodiversité et de biomasse. Ils fournissent des fonctions importantes, comme des refuges et des zones d’alimentation, pour d’autres organismes. Mais, ils sont également vulnérables aux activités humaines, parce qu’ils sont fragiles, croissent lentement et atteignent des records de longévité. Dans les canyons sous-marins, le relief tourmenté, l’hydrodynamisme et l’hétérogénéité des substrats offrent des conditions environnementales propices au développement des habitats coralliens. Dans le Golfe de Gascogne, les coraux d’eau froide sont connus depuis la fin du 19e siècle, mais leur distribution, leur densité et leur rôle fonctionnel avaient été très peu étudiés.Pour augmenter cette connaissance, 24 canyons sous-marins et 3 sites sur l’interfluve/haut de pente contiguë aux canyons adjacents ont été visités par un ROV et une caméra tractée pendant 46 plongées au cours de 7 campagnes océanographiques. Les habitats coralliens définis par le système de classification CoralFISH ont été cartographiés à partir des images prises par les engins sous-marins puis la faune associée, les types de substrat et les déchets ont été annotés.Onze habitats coralliens et 62 morphotypes de coraux ont été observés dans les canyons sous-marins du Golfe de Gascogne hébergeant 191 morphotypes de faune associée, dont 160 morphotypes uniques. Les patrons de distribution à l’échelle locale et à l’échelle régionale pourraient être liés aux régimes hydrodynamiques et sédimentaires. Le type de substrat était important pour les assemblages de coraux et leurs faunes associées, distinguant les habitats biogéniques, sur substrat dur et sur substrat meuble. Les assemblages de coraux étaient similaires entre habitats biogéniques et habitats sur substrat dur, mais la faune associées était plus abondante et diversifiée sur les habitats biogéniques. La diversité-alpha, -beta et –gamma étaient étonnement élevée sur les habitats coralliens sur substrat meuble, égalant ou dépassant la diversité des habitats biogéniques.Les déchets marins étaient abondants et principalement composés de plastiques et de matériels de pêche. Ces déchets pourraient impacter les habitats coralliens : ils ont été trouvés à des profondeurs similaires et les déchets étaient piégés par des reliefs créés par des structures biologiques et géologiques. L’ocurrence des récifs de coraux préférentiellement sur les pentes plus abruptes des canyons sous-marins tandis que les débris de coraux sont plus fréquents sur des aires plus plates de l’interfluve ou du haut de pente, pourraient indiquer un impact de la pêche.Cette étude a contribué à l’initiative en cours de création d’un réseau Natura 2000 qui protégera à terme l’habitat « récif » dont les habitats coralliens biogéniques et sur substrat dur, mais pas les habitats coralliens sur substrat meuble. Pour ces derniers, un complément d’étude et d’autres stratégies de préservation seront nécessaires. / Cold-water coral (CWC) habitats formed by colonial scleractinians, gorgonians, antipatharians and sea pens are biodiversity and biomass hotspots that provide important functions, such as shelter and feeding grounds, to other organisms. But, they are also vulnerable to human activities, because they are long-lived, grow slowly and have a low resistance. Submarine canyons may offer the environmental conditions needed for CWC habitat development, due to their steep topography, complex hydrodynamics and substrate heterogeneity. In the Bay of Biscay, which margin is incised by hundreds of canyons, CWCs are known to exist since the late 19th century, but their distribution, density and functional role remained largely unknown, which impaired their preservation.To increase this knowledge, 24 canyons and three locations between adjacent canyons were visited with an ROV and a towed camera system during 46 dives on 7 cruises. Images were analysed for CWC habitats using the CoralFISH classification system. Within these habitats, corals, associated fauna were identified and substrate cover measured. Litter was identified in 15 out of 24 canyons.Eleven coral habitats constructed by 62 coral morphotypes were observed in the canyons of the Bay of Biscay hosting 191 associated megafaunal morphotypes, including 160 unique morphotypes. The distribution patterns at regional and local scales could be linked to hydrodynamics and sedimentary regimes. Substrate type was an important driver for coral and associated faunal assemblages, distinguishing biogenic, hard substrate and soft substrate habitats. Coral assemblages were similar between biogenic and hard substrate habitats, but the associated fauna was more abundant and diverse on biogenic habitats. The alpha, beta and gamma diversity was surprisingly high on soft substrate habitats, equalling or exceeding that of biogenic habitats.Marine litter was abundant and was mainly composed of plastic items and fishing gear. Litter could co-occur with CWCs and impact them: litter and most CWC habitats were observed at similar water depths and litter was more abundant in areas with a seafloor relief created by biological or geological features. Observations of coral reefs on steeper areas in the canyons and coral debris on flatter areas on the interfluve/upper slope may indicate a potential impact of the fishing industry. This study supports the ongoing effort to create a Natura 2000 network that will protect biogenic and hard substrate habitats, but also points out the need to develop a framework for the preservation of coral habitats on soft substrate.
34

Processus gravitaires tardi-quaternaires dans les canyons et chenaux sous-marins du Saint-Laurent (Est du Canada)

Normandeau, Alexandre 23 April 2018 (has links)
Tableau d'honneur de la Faculté des études supérieures et postdorales, 2014-2015 / Les canyons et chenaux sous-marins sont formés par des courants de densité subaquatiques et sont les principaux conduits par lesquels les sédiments continentaux atteignent les milieux marins profonds. Plusieurs canyons et chenaux sous-marins incisent les marges de l’estuaire et du golfe du Saint-Laurent jusqu’à une profondeur de ≥ 300 m. Des données hydroacoustiques et sédimentologiques récemment acquises ont permis d’analyser en détail la morphologie et les processus sédimentaires tardi-quaternaires qui ont modifié l’architecture de ces systèmes turbiditiques. Quatre types de systèmes turbiditiques ont été identifiés en fonction de leur source respective de sédiments. Un premier type de système, alimenté par la dérive littorale, a été cartographié dans les secteurs de Sept-Îles, Les Escoumins et Tadoussac. La formation et l’évolution de ces trois systèmes semblent être étroitement liées à un apport sédimentaire provenant de l’érosion des rives avoisinantes. Vers la mi-Holocène, alors que la charge sédimentaire provenant des rivières a drastiquement diminué, l’érosion des fronts deltaïques a vraisemblablement contribué à alimenter ces systèmes turbiditiques. L’activité gravitaire est aujourd’hui dominée par des mouvements de masse qui permettent le transfert sédimentaire vers le niveau de base. Un second type de canyon a été découvert dans le secteur de Pointe-des-Monts. Bien qu’il ne reçoive pas d’apport sédimentaire, ce dernier est le seul où des formes en croissant, probablement associées à des courants supercritiques, ont migré récemment. Leur activité holocène peut être expliquée par des mouvements de masse épisodiques et des courants quasi-continus d’origine hydrodynamique se déplaçant sur le plancher marin. Des données sédimentologiques suggèrent que ces courants d’origine hydrodynamique seraient responsables de la formation des canyons. Deux autres types de chenaux et canyons ont été identifiés dans l’estuaire, soit des systèmes reliés aux rivières et aux glaciers. Ces deux types de systèmes ont été actifs majoritairement au début de l’Holocène, alors que la charge sédimentaire transportée vers l’estuaire était plus importante, permettant la génération de courants hyperpycnaux. Ainsi, cette recherche a permis de démontrer la variabilité morphologique des canyons et chenaux de l’estuaire et du golfe du Saint-Laurent ainsi que les différentes phases d’activité et types de processus gravitaires qui ont mené à la formation de systèmes turbiditiques dans un contexte tectonique et climatique similaire. / Submarine canyons and channels are formed by subaqueous sediment density flows and are the main conduits through which continental sediments reach deeper sedimentary basins. Numerous submarine canyons and channels incise the margins of the Estuary and Gulf of St. Lawrence, to a depth of ≥ 300 m. Multibeam bathymetry, acoustic backscatter, seismic reflection and sedimentological analysis have allowed examining in great detail the morphology and the late-Quaternary sedimentary processes within these systems. Four types of submarine fans were identified based on their respective source of sediment. A submarine fan located in ≤ 60 m deep in the Sept-Îles sector has illlustrated the role of longshore drift on the formation and evolution of such systems. Longshore drift, through submarine transverse bars and coastal sand bars, forced the formation of a submarine fan near 5 ka BP. Its activity is now dominated by the passage of low density/intensity flows forming sandwaves on the edge of the coastal shelf and high energy flows (probably slope failures) that allow the accumulation of sediment on the deeper submarine fan. Two other systems fed by longshore drift were identified in the Tadoussac and Les Escoumins sectors, where similar recent episodic activity has been described. A second type of canyon system was discovered in the Pointe-des-Monts sector. These canyons are sediment-starved and yet, they are the only systems in which crescentic bedforms recently migrated upslope. Their short- and long-term activity can be explained by slope failures and quasi-continuous hydrodynamic processes along the seafloor. Sedimentological data suggest that quasi-continuous flows of hydrodynamic origin are responsible for the formation of the canyons. Two other types of channels and canyons were identified in the St. Lawrence: systems fed by rivers and glaciers. Both types of systems were active mainly in the early-Holocene, when sediment supply to the St. Lawrence was greater. When sediment supply drastically diminished during mid-Holocene, erosion of deltaic fronts likely led to an increase in longshore-drift transport and the formation and/or continuated activity of the Sept-Îles and Les Escoumins systems.
35

Forma e arborização em cânions urbanos: tendências de estresse térmico para o pedestre em cenários futuros de Umuarama/PR / Form and afforestation in urban canyons: trends of pedestrian thermal stress in future scenarios of Umuarama-PR

Lima, Diana Carla Rodrigues 07 November 2017 (has links)
A evolução da forma urbana adequada ao seu contexto climático é determinante para a qualidade ambiental dos espaços abertos. Porém, em diversas cidades o crescimento urbano acelerado ocorre quase sem nenhum controle ou planejamento. Esse descontrole é apontado como causa de prejuízos ao ambiente natural e construído, entre eles, o desconforto térmico nos espaços abertos. No Brasil, o Plano Diretor é o instrumento dos governos municipais que regula o desenho urbano; no entanto, nota-se um distanciamento entre os aspectos ambientais e a formulação dos planos e leis municipais. A cidade de Umuarama, no noroeste do Paraná, tem assistido a um intenso crescimento urbano, porém, ainda há na cidade uma flexibilidade para a gestão da forma urbana. Atualmente, está em fase de aprovação o novo Plano Diretor Municipal, que propõe a ampliação da área urbana onde é permitida a verticalização, e o Plano Municipal de Arborização Urbana, que busca promover o controle e o aumento da arborização urbana. Face ao proposto pelos planos, essa pesquisa tem como objetivo principal verificar as tendências de estresse térmico no nível do pedestre em futuros cenários de cânions urbanos na área central de Umuarama. O cânion urbano, referente ao espaço conformado pela via e edifícios adjacentes, foi adotado como objeto de estudo por se constituir na menor unidade microclimática urbana e no principal espaço aberto de uso público. A metodologia aplicada se baseia em levantamento de dados em campo; simulação de diferentes cenários de configuração urbana através de modelagem microclimática com o programa ENVI-met, para situação de verão e inverno; e aplicação do índice de conforto térmico Temperatura Fisiológica Equivalente - PET. Os resultados demonstraram que diferentes combinações dos parâmetros da forma urbana, especificamente, da geometria do cânion urbano e arborização presente no seu interior, resultam em tendências diversas de estresse térmico para o pedestre. Os maiores níveis de estresse térmico no nível do pedestre foram observados no período diurno, em situação de verão; esses níveis tendem a ser menores com o aumento da relação H/W e da arborização no interior dos cânions urbanos. Além disso, verificou-se menor amplitude térmica em cânions com maior cobertura verde. Em cânions urbanos com orientação N-S, o aumento da cobertura verde no interior do cânion urbano foi mais importante para a redução do índice PET do que em cânions com orientação L-O; por outro lado, nesses cânions com orientação L-O, o aumento da relação H/W foi mais representativo para minimizar o PET. A compreensão do comportamento do PET nos diversos cenários demonstrou que novas configurações da forma urbana são compatíveis com a qualidade ambiental dos espaços abertos desde que aplicadas estratégias do desenho urbano climaticamente orientado. Ao final, com base nos resultados, foram traçadas recomendações relacionadas à geometria e cobertura verde das vias urbanas a favor do conforto térmico dos usuários desses espaços. / The appropriate evolution of urban form for your climate context is determinant to open spaces environmental quality. However, it is observed that in several cities the accelerated urban growth occurs almost without any control or planning. This lack of control is pointed as the cause of damage to the built and natural environment, including the thermal discomfort in open spaces. In Brazil, the Master Plan is the instrument of the municipal governments that regulates the urban design; however, there is a gap between environmental aspects and the formulation of plans and municipal laws. The city of Umuarama in the Northwest of Paraná, has seen an intense urban growth, however, there is still a flexibility to the management of urban form. Actually, the new municipal Master Plan is in the aproval phase, it proposes the expansion of the urban area where verticalization is permitted, and the municipal urban afforestation plan, that seeks to promote and control the increase of urban afforestation. In view of proposed plans, this research has as main objective to verify the trends of thermal stress in the pedestrian\'s level in future scenarios of urban canyons in the central area of Umuarama. The urban canyon, referring to the space formed by the via and adjacent buildings, was adopted as object of study because it is the smallest unit microclimatic and the main urban open space for public use. The methodology applied is based on in loco data collection; simulation of different scenarios of urban setting through microclimatic modeling with the ENVI-met program, for summer and winter condition; and application of thermal comfort index Physiological Equivalent Temperature - PET. The results showed that different combinations of the urban form parameters, specifically, the urban canyon geometry and afforestation present in your interior, result in various trends of thermal stress to the pedestrian. The highest levels of thermal stress in the pedestrian level were observed during the day, in summer; these levels trend to be smaller with increasing H/W ratio and afforestation in urban canyons. In addition, there has been less thermal amplitude in canyons with more green coverage. In urban canyons with N-S orientation, increasing the green coverage inside the urban canyon was more important for the reduction of the PET index than in the canyons with L-O orientation; on the other hand, in those canyons with L-O orientation, increasing the H/W ratio was more representative to minimize the PET. Understanding PET behavior in different scenarios demonstrated that new urban form settings are compatible with the open spaces environmental quality since applied urban design strategies climatically guided. In the end, based on the results, were delineated recommendations related urban streets geometry and green coverage in favour of thermal comfort of the users of these spaces.
36

GERAÇÃO PROCEDURAL DE CENÁRIOS 3D DE CÂNIONS COM FOCO EM JOGOS DIGITAIS / GERAÇÃO PROCEDURAL DE CENÁRIOS 3D DE CÂNIONS COM FOCO EM JOGOS DIGITAIS / PROCEDURAL GENERATION OF 3D SCENES FEATURING CANYONS FOCUSED ON DIGITAL GAMES / PROCEDURAL GENERATION OF 3D SCENES FEATURING CANYONS FOCUSED ON DIGITAL GAMES

Carli, Daniel Michelon de 05 March 2012 (has links)
This Master s thesis proposes a non-assisted procedural method for 3D canyons scenes generation based on techniques of computer graphics, computer vision and graph search algorithm. In order to define all the features to be reproduced in our scenes, we have analyzed several images of real canyons and have categorized them in two canyon features models: a recursive and an ordinary one. The proposed approach manipulates a heightmap, created using Perlin noise, in order to imitate the geological features formation previously analyzed. Several parametrizations are used to guide and constraint the generation of terrains, canyons features, course of river, plain areas, soft slope regions, cliffs and plateaus. This work also uses the Mean Shift algorithm as mechanism of segmentation to define regions of interest. A binary mask, with plain areas, is defined based on a threshold operation by a given data set provided by the Mean Shift algorithm. Thereafter a connected-component labeling algorithm is executed using the previously binary mask. This algorithm finds all plains centroids. Right after that, the Dijkstra s algorithm is performed in order to connect all plain areas, creating a valid path between the centroids. The Dijkstra s algorithm is executed again to define the river s course. Finally, a Gaussian smoothing operation is applied to interpolate the soft slope regions. The combination of all those techniques produces as a result automatically generated feature-rich canyons. / Esta dissertação propõe um método procedural não assistido, baseado em técnicas de computação gráfica, visão computacional e busca em grafos, para a geração de cenários 3D de cânions com foco em jogos digitais. Para definir as características a serem reproduzidas, foram analisadas diversas imagens de cânions reais chegando-se em dois modelos, um comum e outro recursivo. A abordagem proposta manipula um reticulado gerado com ruído de Perlin, moldando assim as características inerentes a essa formação geológica. São levadas em conta as diversas parametrizações necessárias para permitir que o algoritmo construa cânions com curso de rio, áreas de planícies, regiões de encosta suave, estruturas de penhascos e, por fim, planaltos nas regiões mais altas. Para atingir o resultado final, o trabalho utiliza o algoritmo Mean Shift como mecanismo de segmentação, definindo dados e regiões de interesse. Munido dos dados do algoritmo de clusterizacao, é definido um limiar para a criação de uma máscara binária com a definição das planícies. Em um segundo momento, um algoritmo de rotulação de componentes conectados é executado, extraindo-se os centróides de cada planície. Por sua vez, o algoritmo de Dijkstra encaixa-se na definição de rotas que conectam estas planícies. O algoritmo de Dijkstra é, então, executado novamente, tendo por base uma função de custo de inclinação, para definir o curso do rio. Por fim, uma filtragem espacial baseada em um filtro Gaussiano é aplicada para interpolar as regiões de encostas de declive suave. A combinação dessas técnicas gera terrenos com grande variabilidade e com as características inerentes à formação geológica de cânions.
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Forma e arborização em cânions urbanos: tendências de estresse térmico para o pedestre em cenários futuros de Umuarama/PR / Form and afforestation in urban canyons: trends of pedestrian thermal stress in future scenarios of Umuarama-PR

Diana Carla Rodrigues Lima 07 November 2017 (has links)
A evolução da forma urbana adequada ao seu contexto climático é determinante para a qualidade ambiental dos espaços abertos. Porém, em diversas cidades o crescimento urbano acelerado ocorre quase sem nenhum controle ou planejamento. Esse descontrole é apontado como causa de prejuízos ao ambiente natural e construído, entre eles, o desconforto térmico nos espaços abertos. No Brasil, o Plano Diretor é o instrumento dos governos municipais que regula o desenho urbano; no entanto, nota-se um distanciamento entre os aspectos ambientais e a formulação dos planos e leis municipais. A cidade de Umuarama, no noroeste do Paraná, tem assistido a um intenso crescimento urbano, porém, ainda há na cidade uma flexibilidade para a gestão da forma urbana. Atualmente, está em fase de aprovação o novo Plano Diretor Municipal, que propõe a ampliação da área urbana onde é permitida a verticalização, e o Plano Municipal de Arborização Urbana, que busca promover o controle e o aumento da arborização urbana. Face ao proposto pelos planos, essa pesquisa tem como objetivo principal verificar as tendências de estresse térmico no nível do pedestre em futuros cenários de cânions urbanos na área central de Umuarama. O cânion urbano, referente ao espaço conformado pela via e edifícios adjacentes, foi adotado como objeto de estudo por se constituir na menor unidade microclimática urbana e no principal espaço aberto de uso público. A metodologia aplicada se baseia em levantamento de dados em campo; simulação de diferentes cenários de configuração urbana através de modelagem microclimática com o programa ENVI-met, para situação de verão e inverno; e aplicação do índice de conforto térmico Temperatura Fisiológica Equivalente - PET. Os resultados demonstraram que diferentes combinações dos parâmetros da forma urbana, especificamente, da geometria do cânion urbano e arborização presente no seu interior, resultam em tendências diversas de estresse térmico para o pedestre. Os maiores níveis de estresse térmico no nível do pedestre foram observados no período diurno, em situação de verão; esses níveis tendem a ser menores com o aumento da relação H/W e da arborização no interior dos cânions urbanos. Além disso, verificou-se menor amplitude térmica em cânions com maior cobertura verde. Em cânions urbanos com orientação N-S, o aumento da cobertura verde no interior do cânion urbano foi mais importante para a redução do índice PET do que em cânions com orientação L-O; por outro lado, nesses cânions com orientação L-O, o aumento da relação H/W foi mais representativo para minimizar o PET. A compreensão do comportamento do PET nos diversos cenários demonstrou que novas configurações da forma urbana são compatíveis com a qualidade ambiental dos espaços abertos desde que aplicadas estratégias do desenho urbano climaticamente orientado. Ao final, com base nos resultados, foram traçadas recomendações relacionadas à geometria e cobertura verde das vias urbanas a favor do conforto térmico dos usuários desses espaços. / The appropriate evolution of urban form for your climate context is determinant to open spaces environmental quality. However, it is observed that in several cities the accelerated urban growth occurs almost without any control or planning. This lack of control is pointed as the cause of damage to the built and natural environment, including the thermal discomfort in open spaces. In Brazil, the Master Plan is the instrument of the municipal governments that regulates the urban design; however, there is a gap between environmental aspects and the formulation of plans and municipal laws. The city of Umuarama in the Northwest of Paraná, has seen an intense urban growth, however, there is still a flexibility to the management of urban form. Actually, the new municipal Master Plan is in the aproval phase, it proposes the expansion of the urban area where verticalization is permitted, and the municipal urban afforestation plan, that seeks to promote and control the increase of urban afforestation. In view of proposed plans, this research has as main objective to verify the trends of thermal stress in the pedestrian\'s level in future scenarios of urban canyons in the central area of Umuarama. The urban canyon, referring to the space formed by the via and adjacent buildings, was adopted as object of study because it is the smallest unit microclimatic and the main urban open space for public use. The methodology applied is based on in loco data collection; simulation of different scenarios of urban setting through microclimatic modeling with the ENVI-met program, for summer and winter condition; and application of thermal comfort index Physiological Equivalent Temperature - PET. The results showed that different combinations of the urban form parameters, specifically, the urban canyon geometry and afforestation present in your interior, result in various trends of thermal stress to the pedestrian. The highest levels of thermal stress in the pedestrian level were observed during the day, in summer; these levels trend to be smaller with increasing H/W ratio and afforestation in urban canyons. In addition, there has been less thermal amplitude in canyons with more green coverage. In urban canyons with N-S orientation, increasing the green coverage inside the urban canyon was more important for the reduction of the PET index than in the canyons with L-O orientation; on the other hand, in those canyons with L-O orientation, increasing the H/W ratio was more representative to minimize the PET. Understanding PET behavior in different scenarios demonstrated that new urban form settings are compatible with the open spaces environmental quality since applied urban design strategies climatically guided. In the end, based on the results, were delineated recommendations related urban streets geometry and green coverage in favour of thermal comfort of the users of these spaces.
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Impact des variations du climat et du niveau marin sur les canyons sous-marins du Golfe du Lion (France) et de la marge de l'Ebre (Catalogne) au cours du Plio-Quaternaire / Impact of climate and sea-level variations on submarine canyons in the Gulf of Lions (France) and on the Ebro margin (Catalonia) during the Plio-Quaternary.

Mauffrey, Marie-Aline 17 December 2015 (has links)
Les fluctuations du climat et du niveau marin, de plus ou moins grande amplitude, influencent le taux d’érosion sur le continent, le transport de sédiment vers l’océan et sa distribution vers le bassin profond. Les canyons sous-marins, structures érosives de premier abord, sont les zones de transfert privilégiées entre le plateau continental et le bassin profond. Peu d’études se sont concentrées sur la relation entre le remplissage des canyons, l’acheminement des sédiments et les variations du niveau marin. La chronologie de leur mise en place et de leur évolution aux échelles de temps géologiques restent également largement spéculatifs. Ce travail est consacré à la genèse des canyons sous-marins au Plio-Quaternaire sur les marges de l’Ebre et du Golfe du Lion, en Méditerranée occidentale. Cette genèse intervient après la crise de salinité messinienne, qui a conduit au démantèlement par érosion continentale des marges méditerranéennes. Après une initiation par érosion régressive au Pliocène, les canyons sous-marins connaissent un développement majeur lors de la mise en place des cycles climatiques de 100 ka au Quaternaire, en lien avec l’amplification des oscillations du niveau marin pouvant atteindre 150 m. L’utilisation et la comparaison de données sismiques (2D et 3D) de résolution et pénétration différentes, couplées à des calages chrono-stratigraphiques par forages, permettent de mettre en évidence le lien important entre les cycles climatiques de Milankovitch (principalement 100 et 41 ka) et l’architecture des têtes de canyons. Les changements rapides du climat et du niveau marin (cycles de Bond) ont également une influence importante sur le flux sédimentaire et les processus de transport, ainsi que sur la connexion/déconnexion avec les systèmes fluviatiles. / Climate and sea-level changes with various magnitudes control continental erosion, sediment transport and its delivery to the deep basin. Submarine canyons, that are erosional features at a first glance, are conduits for sediment transport from the continental shelf to the deep sea. Little studies focused on the relationship between canyon infill, sediment delivery and sea-level variations. The chronology of canyon development and evolution through geological time remains speculative. This thesis is dedicated to the understanding of the genesis of submarine canyons in the western Mediterranean Sea during the Plio-Quaternary. This period occurred after the major erosion of Mediterranean continental margins during the Messinian Salinity Crisis. Canyons were initiated by retrogressive erosion during the Pliocene. They further developed in relation with the amplification of sea-level changes during the Quaternary (up to 150 m). The results are based on a large range of 2D and 3D seismic data resolution and chrono-stratigraphic constraints. The stratigraphic signature of Milankovitch (mainly 100 and 40 ka) is revealed within canyon heads. Rapid climate and sea-level changes (Bond Cycles) have also a distinct signature by controlling the type and amount of sediment delivered in canyon heads, and the connection/disconnection with fluvial systems.

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