• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 32
  • 28
  • 5
  • 5
  • 5
  • 4
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 94
  • 14
  • 11
  • 10
  • 9
  • 9
  • 8
  • 8
  • 8
  • 8
  • 8
  • 6
  • 6
  • 6
  • 6
  • 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.
81

Разработка рекомендаций по проектированию антенной системы для аэрологических исследований атмосферы : магистерская диссертация / Development of recommendations for the design of an antenna system for aerological exploration of the atmosphere

Трифонов, Д. А., Trifonov, D. A. January 2020 (has links)
Рассмотрены различные способы измерений скорости ветра на различной высоте в нижних слоях атмосферы. Предложена новая конструкция радара для неконтактного измерения скорости ветра. В качестве излучателя антенной решетки предложено использовать трехэлементную вибраторную антенну. Выполнено электродинамическое моделирование антенной решетки. Предложена антенная решетка, формирующая 5 лучей шириной 7 градусов. Рассмотрена треугольная и квадратная сетка размещения элементов. Доказано преимущество антенной решетки с треугольной сеткой. Рассмотрено влияние амплитудного распределения мощности по элементам антенной решетки на диаграмму направленности. Исследовано влияние кластеризации решетки по 4 и 7 элементов. Доказано преимущество 4-х элементных кластеров. Исследовано влияние дискрета фазирования на характеристики антенны. Предложена 4-битовая схема фазовращателей. Схема управления фазовращателями оптимизирована на минимум управляющего тока. Определена дальность действия предложенного радара. / Various methods of wind speed measuring at different heights in the lower atmosphere are considered. A new scheme for constructing a radar for non-contact measurement of wind speed is proposed. A three-element dipole antenna is proposed as the radar antenna array element. The antenna array electrodynamic modeling is performed. The antenna array forming 5 beams with a width of 7 degrees are suggested. The square and triangular grid of elements placement in the antenna array is considered. The advantages of the antenna array with the triangular grid are justified. The influence of the amplitude distribution of radiated power in the antenna array on the radiation pattern is studied. The effect of clustering of the antenna array on its radiation is studied. 4- and 7-element clusters are considered. The advantage of 4-element clusters is proved. The effect of phasing discretization on the antenna characteristics is investigated. The 4-bit phase shifter scheme is proposed. The phase shifter control scheme is optimized for a minimum of the control current. The radar monitoring range is defined.
82

Evaluation of the Automated Laser Rut Measurement System Used by the Ohio Department of Transportation

Hoffman, Bradley R. January 2011 (has links)
No description available.
83

Attrahera mera och anställ flera : En jämställd grafisk profil för företag i tillverkningsindustrin / Design For All, Equality's Call : An gender equal graphic profile for companies in the manufacturing industry

Phionuan, Supreeya, Eriksson, Adam January 2024 (has links)
Könssegregerade arbetsplatser och yrkesområden är något som kan vara till företagets nackdel, då det har visat sig att könssegregering kan bidra till sämre resultat och arbetsklimat. Segregeringen gör det också svårare för arbetsgivare att hitta rätt kompetens, vilket är ett stort problem i Värmland och anledningen till att projektet “Attraktionskraft Värmland” har startats av regionen. Projektet vill, tillsammans med företagen, göra arbetsmarknaden mer jämställd och minska segregeringen för att eliminera den kompetensbrist som råder i länet. En av de könssegregerade branscherna i Värmland är tillverkningsindustrin, som överrepresenteras av män.  Med inspiration av detta är syftet med studien att undersöka hur man kan locka fler kvinnliga medarbetare till branschen genom att ändra de fördomar och stereotyper som finns kring den. Detta med hjälp av att använda den grafiska profilen för att uttrycka jämställdhet och signalera att arbetsplatsen är inbjudande för alla kön. Studiens frågeställningar blev då:  På vilket sätt uttrycks jämställdhet genom semiotiska tecken i den grafiska profilen för företag inom tillverkningsindustrin i Värmland? Vad finns det för visuella element som kan vara problematiskt kopplat till jämställdhet i en grafisk profil? För att uppnå detta användes Luptons (2011) designprocess och en semiotisk multimodal analys av hemsidor från företag inom tillverkningsindustrin i Värmland. Tillsammans med den tidigare forskningen, teorier och resultatet av analysen visade analysen att sådant som färg, form, samt representation av kön och könsroller är påverkande i huruvida uttrycket på en hemsida upplevs som maskulint eller feminint. Efter analysen togs det fram en grafisk profil och mockup på hemsida som exempel på hur det går att använda dessa grafiska element för att skapa ett uttryck som inte diskriminerar något kön samt kan upplevas som inbjudande för alla könsidentiteter. Exemplet ska också visa hur det går att ändra den grafiska profilen med dessa aspekter i åtanke utan att tappa företagets grundvärderingar och identitet. Nyckelord: Grafisk design, grafiska profiler, jämställdhet, visuell kommunikation, employer branding / Gender-segregated workplaces and industries are something that can be to the company's disadvantage, as it has been shown that gender segregation can contribute to poorer results and work climate. Segregation also makes it more difficult for employers to find the right skills, which is a major problem in Värmland and the reason why the project "Attraction Värmland" has been launched by the region. Together with businesses, the project aims to make the labor market more equal and reduce segregation to eliminate the skills shortage in the county. One of the most gender-segregated sectors in Värmland is the manufacturing industry, which is overrepresented by men. Inspired by this, the purpose of the study is to explore how to attract more female employees to that industry by changing the prejudices and stereotypes surrounding it. This is done by using the graphic profile to express gender equality and signal that the workplace is inviting to all genders. The study's questions then became: How is gender equality expressed through semiotic signs in the graphic profile of companies in the manufacturing industry in Värmland? What visual elements can be problematic in relation to gender equality in a graphic profile? To achieve this, Lupton's (2011) design process and a semiotic multimodal analysis of websites from companies in the manufacturing industry in Värmland were used. Together with the previous research, theories, and the results of the analysis, the study showed that things like color, shape, and representation of gender and gender roles are influential in whether the expression on a website is perceived as masculine or feminine. After the analysis, a graphic profile and mockup of the website were developed as an example of how it is possible to use these graphic elements to create an expression that does not discriminate against any gender and can be perceived as inviting to all gender identities. The example also wants to show how it is possible to change the graphic profile with these aspects in mind without losing the company's core values and identity. Keywords: Graphic design, graphic profiles, gender equality, visual communication, employer branding
84

”Det är det största jag gjort för min personliga utveckling” : Gymnasielevers upplevelser kring FN-rollspel i samhällkunskapsundervisningen / ”The greatest thing I´ve done for my personal development” : Upper secondary school students’ experiences with Model UN in civicseducation

Pedersen, Hanna January 2024 (has links)
This study aims to provide insights into Swedish upper secondary school students experiences with Model UN, a roleplay simulation of the United Nations General Assembly, and it´scontributions to the development of knowledge and skills in civics education. Examining Model UN is crucial for evaluating its pedagogical effectiveness and understanding students' perspectives and experiences. It is also essential to investigate how Model UN can enhance students' understanding of societal issues and international relations, particularly in a time of increasing global complexities. By exploring questions that emphasize the function of roleplaying as a tool for increased understanding of societal issues, international relations, and democracy, as well as students' interpretations of participation, the study aims to enhance understanding of how Model UN can benefit students' learning and development.The study utilizes theoretical frameworks that draws from civics didactics such as Christina Odenstad´s (2010) subject profiles and Sara Blanck´s (2014) subject didactics to examine the impact of model UN simulations. Odenstad (2010) categorizes social studies or civics into orientation subject, analysis subject, and discussion subject, while Blanck (2014) adds a subject didactic aspect emphasizing the ability to act and citizenship education. These profiles help analyse how Model UN contributes to students' learning and skills development.Drawing from interviews with upper secondary school students, the study finds that Model UN simulations is an engaging teaching method where students perceive significant development. Students' interest and engagement in societal issues rises, and by assuming roles and discussing crucial topics, they gain a deeper understanding of subjects such as politics and democracy. Factual knowledge develops through participation in role-playing, aiding students in effective argumentation and understanding diverse perspectives. Following the simulations, students emphasize the importance of nuanced analysis, which has enhanced their critical thinking and ability to avoid falling victim to propaganda. Students who participated in Model UN describe developing skills in oral presentation, self-confidence, political self-efficacy, and understanding beyond facts. Through their experiences, they describe a collective journey of nervousness, uncertainty, and growth.The experience led them to realize that political issues are more nuanced than they previously believed, emphasizing the importance of being prepared for counterarguments and understanding different viewpoints. They believe that the practical approach of role-playing is a valuable complement to traditional theoretical education and advocate for more inclusion of such activities in school curricula. Model UN was an enriching and rewarding experience that not only strengthened their skills but also increased their understanding of political issues and international relations. They stress that such activities should become available to more students to promote a deeper understanding and a more engaged approach to societal issues.The study's findings indicate that Model UN provided a breadth in education where all four didactic profiles were demonstrated and developed, suggesting that UN role-playing can be a useful teaching tool in civics education.
85

Performance Optimisation of Discrete-Event Simulation Software on Multi-Core Computers / Prestandaoptimering av händelsestyrd simuleringsmjukvara på flerkärniga datorer

Kaeslin, Alain E. January 2016 (has links)
SIMLOX is a discrete-event simulation software developed by Systecon AB for analysing logistic support solution scenarios. To cope with ever larger problems, SIMLOX's simulation engine was recently enhanced with a parallel execution mechanism in order to take advantage of multi-core processors. However, this extension did not result in the desired reduction in runtime for all simulation scenarios even though the parallelisation strategy applied had promised linear speedup. Therefore, an in-depth analysis of the limiting scalability bottlenecks became necessary and has been carried out in this project. Through the use of a low-overhead profiler and microarchitecture analysis, the root causes were identified: atomic operations causing a high communication overhead, poor locality leading to translation lookaside buffer thrashing, and hot spots that consume significant amounts of CPU time. Subsequently, appropriate optimisations to overcome the limiting factors were implemented: eliminating the expensive operations, more efficient handling of heap memory through the use of a scalable memory allocator, and data structures that make better use of caches. Experimental evaluation using real world test cases demonstrated a speedup of at least 6.75x on an eight-core processor. Most cases even achieve a speedup of more than 7.2x. The various optimisations implemented further helped to lower run times for sequential execution by 1.5x or more. It can be concluded that achieving nearly linear speedup on a multi-core processor is possible in practice for discrete-event simulation. / SIMLOX är en kommersiell mjukvara utvecklad av Systecon AB, vars huvudsakliga funktion är en händelsestyrd simuleringskärna för analys av underhållslösningar för komplexa tekniska system. För hantering av stora problem så används parallellexekvering för simuleringen, vilket i teorin borde ge en nästan linjär skalning med antal trådar. Prestandaförbättringen som observerats i praktiken var dock ytterst begränsad, varför en ordentlig analys av skalbarheten har gjorts i detta projekt. Genom användandet av ett profileringsverktyg med liten overhead och mikroarkitektur-analys, så kunde orsakerna hittas: atomiska operationer som skapar mycket overhead för kommunikation, dålig lokalitet ger fragmentering vid översättning till fysiska adresser och dåligt utnyttjande av TLB-cachen, och vissa flaskhalsar som kräver mycket CPU-kraft. Därefter implementerades och testade optimeringar för att undvika de identifierade problem. Testade lösningar inkluderar eliminering av dyra operationer, ökad effektivitet i minneshantering genom skalbara minneshanteringsalgoritmer och implementation av datastrukturer som ger bättre lokalitet och därmed bättre användande av cache-strukturen. Verifiering på verkliga testfall visade på uppsnabbningar på åtminstone 6.75 gånger på en processor med 8 kärnor. De flesta fall visade på en uppsnabbning med en faktor större än 7.2. Optimeringarna gav även en uppsnabbning med en faktor på åtminstone 1.5 vid sekventiell exekvering i en tråd. Slutsatsen är därmed att det är möjligt att uppnå nästan linjär skalning med antalet kärnor för denna typ av händelsestyrd simulering.
86

Étude numérique des circulations locales à la Réunion : application à la dispersion de polluants / Numerical studies of local atmospheric circulations over Reunion Island : application to the dispersion of pollutants

Lesouëf, Dorothée 28 October 2010 (has links)
Les régimes dynamiques dans les basses couches de l’atmosphère à l’île de la Réunion sont conditionnés par l’action du relief et du rayonnement sur l’écoulement synoptique. L’île est située en permanence dans le flux des alizés de sud-est et son relief élevé, culminant à 3000 m dans le centre de l’île et 2600 m au sud, constitue un obstacle important pour l’écoulement moyen. Le relief, le chauffage différentiel des pentes et le contraste thermique avec l’océan influent sur les échanges locaux entre la couche limite marine et la troposphère libre.L’analyse des phénomènes complexes de l’écoulement atmosphérique au niveau de l’île a pour but initial de caractériser les transferts de polluants émis localement. Cette étude a deux applications : • La première rentre dans le cadre préparatoire à la mise en place, à 2200 m d’altitude sur le Piton Maïdo, de l’observatoire atmosphérique de l’OPAR, à l’horizon 2011. L’objectif est de comprendre les circulations locales induites par le relief et les transports associés afin de discriminer d’éventuelles pollutions par les sources locales sur le signal qui sera mesuré in situ au sommet du Maïdo.• La seconde vise à étudier la diffusion des panaches volcaniques du Piton de la Fournaise. L’éruption majeure d’avril 2007 du volcan réunionnais a montré que des panaches pouvaient générer d’importantes pollutions dans diverses parties de l’île allant jusqu’à poser de réels problèmes environnementaux et de santé publique.Ces applications s’appuient sur une étude par modélisation numérique à haute résolution des écoulements atmosphériques dans les basses couches au niveau de l’île, au moyen du modèle météorologique de recherche MésoNH, permettant de conduire un ensemble de simulations sur cas idéalisés puis sur cas réels avec diffusion de traceurs passifs. / Reunion Island is an isolated mountainous island in Indian Ocean culminating in the center at 3000 m and in the southern part at 2600 m asl and is located in the influence of very regular south-easterly trade winds. The perturbation of the prevailing humid trade wind flow by the complex topography causes large spatial variations in local weather. The analysis of atmospheric circulations at local scale has been conducted with the aim of improving the understanding of small-scale transport and dispersion of pollutants emitted from local sources. This study has two applications:• It takes part in the perspective of the new atmospheric research station of Piton Maïdo, a summit at 2200 m above sea level on the west coast of the island, in the frame of the developing Atmospheric Physics Observatory of La Reunion (Observatoire de Physique de l’Atmosphère de la Réunion, OPAR as French acronym). The objective is to examine to what extent local orographic perturbations of the synoptic wind and local wind systems are responsible for vertical export of air pollutants originating from the island boundary layer, and could affect ground-based measurements at the future Piton Maïdo observatory devoted to the monitoring of background atmospheric composition (greenhouse gases and aerosols).• The second one aims to investigate the behavior of the volcanic plumes from the Piton de la Fournaise. During the April-May 2007 eruption, large amounts of volcanic gases, particles and ash were released into the atmosphere causing air-pollution at several inhabited locations. In this work, the three-dimensional, non-hydrostatic, limited-area numerical model, MESONH, was run in high resolution to simulate features of airflows over Reunion Island in idealized and real conditions. Various passive tracers have been released in the model in order to characterize dynamical processes in the lower atmospheric layers and the related transport of air-masses.
87

Social Media: How to Interact with Millennials and Make Use of Self-Segmentation : A Case Study of Swedish Millennials’ Behavior on Facebook

Andersson, Simon, Arnvaller, Kevin January 2017 (has links)
Social media are online accommodations where users can interact with other users, which has become a phenomenon that has grown and completely exploded over the past decade. Companies are well aware of this and has invested a large amount of resources in order to establish a better contact with their customers. Companies have several different fields of applications with social media such as gathering information, promotion, communicating with customers and reach out to desired audience effectively. Millennials are the generation who most frequently use social media and also grown up during the phenomenon's development. Previous research has shown that companies have had difficulties in reaching out to the millennial generation. This thesis purpose is to gain a deeper understanding of how companies can use social media to facilitate the segmentation process and effectively reach out to the millennial generation. Therefor two research questions have been established. The two research questions have been answered with assistance from relevant theory and research in the subject area. A case study was applied for the study, where the data was gathered from two focus groups discussing the social media platform Facebook. Each focus group consisted of eight participants within the millennial generation containing basic knowledge in marketing. The study’s result indicates millennials to follow (and thereby self-segment themselves) influential profiles they have a personal interest towards. However, Facebook is not the platform where the millennials follow these profiles. The study also indicates the best way to capture millennials interest on Facebook is through short, humorous videos with an interest capturing beginning. The study’s results also show millennia’s have a low interest in interacting with companies on Facebook. / Sociala medier är onlineplatser där personer kan interagera med varandra. Detta fenomen har vuxit i en accelererande fart under de senaste decenniet och fångat stort intresse hos företag som lägger massiva resurser på att få en bättre kontakt med sina kunder. Företag har åtskilda användningsområden av sociala medier, som till exempel att samla kundinformation, marknadsföra sig, kommunicera med kunder och att nå ut till en önskad målgrupp. Millennials är den generationen som flitigast använder sociala medier och har växt upp under fenomenets utveckling. Tidigare forskning visar att företag har haft svårigheter med att nå ut till millennial generationen. Denna uppsats syfte är därför att ge en djupare förståelse om hur företag kan använda sig av sociala medier för att förenkla segmenteringsprocessen och nå ut till millennial generationen. För att få en djupare förståelse inom område, har vi formulerat två forskningsfrågor. Forskningsfrågorna har i sin tur blivit besvarade med ståndpunkt i relevant teori och forskning inom området. Studien utfördes som en fallstudie, där informationen samlades in från två fokusgrupper som diskuterade Facebook. Vardera fokusgrupp bestod av åtta deltager inom millennial generationen, med grundläggande marknadsförings kunskaper. Studiens resultat indikerar på att millennial generationen följer (och där igenom själv-segmenterar sig själva) inflytande profiler de finner ett personligt intresse för. Dock är Facebook inte den plattform de använder för att följa dessa profiler. Vidare indikerar studien att det bästa sättet att fånga millennial generationens intresse är genom en kort, roligt video, där något intressant händer under de första sekunderna. Studiens resultat visar även att millennial generation inte har något större intresse av att interagera med företag på Facebook.
88

Echo Character and Sedimentary Processes on the Continental Shelf of the São Paulo State / Caráter de Eco e Processos Sedimentares na Plataforma Continental do Estado de São Paulo

Araujo, Ligia Dias de 11 May 2018 (has links)
Sedimentary processes are critical geological phenomena in the evolution of continental margins. Environmental forces from various temporal and spatial scales control these processes. Due to the fast increase of anthropogenic activities in marine environments, these studies on sedimentary processes and their products are becoming increasingly necessary. In this context, geophysical data, such as high-resolution 2D seismic reflection profiles, are efficient tools to characterize sedimentary processes and deposits. This study aimed to map and interpret different types of echo character on the continental shelf of the São Paulo Bight to increase the knowledge of the spatial variability of sedimentary processes in current-dominated shelf settings. With this aim, 120 seismic lines, almost 3200 km in length, have been analyzed in conjunction with 451 surficial sediment samples. Based on the broad-scale seafloor morphology, microtopography and seismic characteristics (e.g., sharpness, amplitude, continuity) of sub-bottom reflections, seven echo types distributed in three echo classes were identified in the study area. Type 1-1 is a flat seafloor with either no or low-amplitude sub-bottom reflectors, mainly observed in the middle shelf; type 1-2 is a flat sea floor with medium to high-amplitude sub-bottom reflectors also found in middle shelf settings; type 1-3 is defined by a transparent acoustic response below the seafloor evolving downsection into a highly reflective pattern that covers most of the inner shelf; type 1-4 presents a flat seafloor molded by regularly spaced undulations, and it is restricted to the outer shelf; type 2-1 consists of mounds with no internal reflectors also located on the outer shelf; type 3-1 is an irregular echo with prolonged internal reflectors found around the São Sebastião Island; finally, type 3-2 is a broad irregular echo with high relief variations mainly found in the outer shelf. The analysis of the seismic survey allowed recognizing that the distribution of the echoes reflects not only the composition of the seabed but also the sedimentary processes that acted during the deposition of the material. In the inner shelf and middle shelves, the Brazilian Coastal Current and the action of waves are the main processes responsible for the echo types found, while the outer shelf echo types are strongly influenced by the Brazil Current. / Processos sedimentares são fenômenos importantes na evolução das margens continentais. Esses processos são controlados por forçantes de várias escalas espaciais e temporais. Devido ao rápido crescimento das atividades antropogênicas em ambientes marinhos, estudos sobre processos sedimentares e seus produtos tem se tornado cada vez mais necessários. Nesse contexto, dados geofísicos, como perfis de sísmica de reflexão de alta resolução, são ferramentas importantes na caracterização desses processos e depósitos. O objetivo do estudo foi mapear e interpretar os tipos de caráter de eco na plataforma continental do estado de São Paulo visando aumentar o conhecimento a respeito da variabilidade espacial dos processos sedimentares em plataformas dominadas por correntes. Para alcançar esse objetivo 120 linhas sísmicas totalizando quase 3200 km em extensão foram analisadas em conjunto com 451 amostras sedimentares. Baseados na morfologia de macro e microescala e características sísmicas do sinal acústico de fundo como nitidez, amplitude e continuidade dos refletores, foram identificados 7 tipos de caráter de eco distribuídos em 3 classes (fundo plano, monticular ou irregular). O tipo 1-1 apresenta fundo plano com refletores de sub fundo ausentes ou de baixa amplitude localizado principalmente na plataforma média; o tipo 1-2 refere-se a um fundo plano com refletores internos com amplitudes médias a altas também presente na plataforma média; o tipo 1-3 é definido por uma camada superficial transparente que é substituída em profundidade por uma camada altamente refletiva que cobre grande parte da plataforma interna; o eco 1-4 apresenta fundo moldado por ondulações com localização restrita na plataforma externa; o tipo 2-1 consiste em montes sem refletores internos localizado próximo a quebra da plataforma; o tipo 3-1 é irregular com refletores internos prolongados e é encontrado ao sul da Ilha de São Sebastião; finalmente, o eco 3-2 é um eco irregular que apresenta grandes variações de relevo presente em grande parte da plataforma externa. A análise dos dados sísmicos permitiu o reconhecimento de que os ecos respondem não somente a composição sedimentar superficial, mas também os processos sedimentares que atuaram durante a deposição do material. Nas plataformas interna e média, a Corrente Costeira Brasileira e a ação de ondas geradas pelos ventos são os principais processos responsáveis pela geração dos ecos encontrados, enquanto na plataforma externa, os tipos de eco são fortemente influenciados pela Corrente do Brasil.
89

Echo Character and Sedimentary Processes on the Continental Shelf of the São Paulo State / Caráter de Eco e Processos Sedimentares na Plataforma Continental do Estado de São Paulo

Ligia Dias de Araujo 11 May 2018 (has links)
Sedimentary processes are critical geological phenomena in the evolution of continental margins. Environmental forces from various temporal and spatial scales control these processes. Due to the fast increase of anthropogenic activities in marine environments, these studies on sedimentary processes and their products are becoming increasingly necessary. In this context, geophysical data, such as high-resolution 2D seismic reflection profiles, are efficient tools to characterize sedimentary processes and deposits. This study aimed to map and interpret different types of echo character on the continental shelf of the São Paulo Bight to increase the knowledge of the spatial variability of sedimentary processes in current-dominated shelf settings. With this aim, 120 seismic lines, almost 3200 km in length, have been analyzed in conjunction with 451 surficial sediment samples. Based on the broad-scale seafloor morphology, microtopography and seismic characteristics (e.g., sharpness, amplitude, continuity) of sub-bottom reflections, seven echo types distributed in three echo classes were identified in the study area. Type 1-1 is a flat seafloor with either no or low-amplitude sub-bottom reflectors, mainly observed in the middle shelf; type 1-2 is a flat sea floor with medium to high-amplitude sub-bottom reflectors also found in middle shelf settings; type 1-3 is defined by a transparent acoustic response below the seafloor evolving downsection into a highly reflective pattern that covers most of the inner shelf; type 1-4 presents a flat seafloor molded by regularly spaced undulations, and it is restricted to the outer shelf; type 2-1 consists of mounds with no internal reflectors also located on the outer shelf; type 3-1 is an irregular echo with prolonged internal reflectors found around the São Sebastião Island; finally, type 3-2 is a broad irregular echo with high relief variations mainly found in the outer shelf. The analysis of the seismic survey allowed recognizing that the distribution of the echoes reflects not only the composition of the seabed but also the sedimentary processes that acted during the deposition of the material. In the inner shelf and middle shelves, the Brazilian Coastal Current and the action of waves are the main processes responsible for the echo types found, while the outer shelf echo types are strongly influenced by the Brazil Current. / Processos sedimentares são fenômenos importantes na evolução das margens continentais. Esses processos são controlados por forçantes de várias escalas espaciais e temporais. Devido ao rápido crescimento das atividades antropogênicas em ambientes marinhos, estudos sobre processos sedimentares e seus produtos tem se tornado cada vez mais necessários. Nesse contexto, dados geofísicos, como perfis de sísmica de reflexão de alta resolução, são ferramentas importantes na caracterização desses processos e depósitos. O objetivo do estudo foi mapear e interpretar os tipos de caráter de eco na plataforma continental do estado de São Paulo visando aumentar o conhecimento a respeito da variabilidade espacial dos processos sedimentares em plataformas dominadas por correntes. Para alcançar esse objetivo 120 linhas sísmicas totalizando quase 3200 km em extensão foram analisadas em conjunto com 451 amostras sedimentares. Baseados na morfologia de macro e microescala e características sísmicas do sinal acústico de fundo como nitidez, amplitude e continuidade dos refletores, foram identificados 7 tipos de caráter de eco distribuídos em 3 classes (fundo plano, monticular ou irregular). O tipo 1-1 apresenta fundo plano com refletores de sub fundo ausentes ou de baixa amplitude localizado principalmente na plataforma média; o tipo 1-2 refere-se a um fundo plano com refletores internos com amplitudes médias a altas também presente na plataforma média; o tipo 1-3 é definido por uma camada superficial transparente que é substituída em profundidade por uma camada altamente refletiva que cobre grande parte da plataforma interna; o eco 1-4 apresenta fundo moldado por ondulações com localização restrita na plataforma externa; o tipo 2-1 consiste em montes sem refletores internos localizado próximo a quebra da plataforma; o tipo 3-1 é irregular com refletores internos prolongados e é encontrado ao sul da Ilha de São Sebastião; finalmente, o eco 3-2 é um eco irregular que apresenta grandes variações de relevo presente em grande parte da plataforma externa. A análise dos dados sísmicos permitiu o reconhecimento de que os ecos respondem não somente a composição sedimentar superficial, mas também os processos sedimentares que atuaram durante a deposição do material. Nas plataformas interna e média, a Corrente Costeira Brasileira e a ação de ondas geradas pelos ventos são os principais processos responsáveis pela geração dos ecos encontrados, enquanto na plataforma externa, os tipos de eco são fortemente influenciados pela Corrente do Brasil.
90

Multi-dimensional Teager-Kaiser signal processing for improved characterization using white light interferometry / Traitement du signal Teager-Kaiser multi-dimensionel pour la caractérisation améliorée avec l'interférométrie en lumière blanche

Gianto, Gianto 14 September 2018 (has links)
L'utilisation de franges d'interférence en lumière blanche comme une sonde optique en microscopie interférométrique est d'une importance croissante dans la caractérisation des matériaux, la métrologie de surface et de l'imagerie médicale. L'Interférométrie en lumière blanche est une technique basée sur la détection de l'enveloppe de franges d'interférence. Il a été démontré antérieurement, la capacité des approches 2D à rivaliser avec certaines méthodes classiques utilisées dans le domaine de l'interférométrie, en termes de robustesse et de temps de calcul. En outre, alors que la plupart des méthodes tiennent compte seulement des données 1 D, il semblerait avantageux de prendre en compte le voisinage spatial utilisant des approches multidimensionnelles (2D/3D), y compris le paramètre de temps afin d'améliorer les mesures. Le but de ce projet de thèse est de développer de nouvelles approches n-D qui sont appropriées pour une meilleure caractérisation des surfaces plus complexes et des couches transparentes. / The use of white light interference fringes as an optical probe in microscopy is of growing importance in materials characterization, surface metrology and medical imaging. Coherence Scanning Interferometry (CSI, also known as White Light Scanning Interferometry, WSLI) is well known for surface roughness and topology measurement [1]. Full-Field Optical Coherence Tomography (FF-OCT) is the version used for the tomographic analysis of complex transparent layers. Both techniques generally make use of some sort of fringe scanning along the optical axis and the acquisition of a stack of xyz images. Image processing is then used to identify the fringe envelopes along z at each pixel in order to measure the positions of either a single surface or of multiple scattering objects within a layer.In CSI, the measurement of surface shape generally requires peak or phase extraction of the mono dimensional fringe signal. Most of the methods are based on an AM-FM signal model, which represents the variation in light intensity measured along the optical axis of an interference microscope [2]. We have demonstrated earlier [3, 4] the ability of 2D approaches to compete with some classical methods used in the field of interferometry, in terms of robustness and computing time. In addition, whereas most methods only take into account the 1D data, it would seem advantageous to take into account the spatial neighborhood using multidimensional approaches (2D, 3D, 4D), including the time parameter in order to improve the measurements.The purpose of this PhD project is to develop new n-D approaches that are suitable for improved characterization of more complex surfaces and transparent layers. In addition, we will enrich the field of study by means of heterogeneous image processing from multiple sensor sources (heterogeneous data fusion). Applications considered will be in the fields of materials metrology, biomaterials and medical imaging.

Page generated in 0.048 seconds