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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.
61

O uso de processamento digital de imagens do sensor Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) na identificação de horizontes coesos em solos dos tabuleiros costeiros da Bahia / The use of digital image processing of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor in the identification of cohesive horizons in soils of the Coastal Tableland of Bahia

Rosângela Leal Santos 21 December 2005 (has links)
Os Tabuleiros Costeiros são unidades geomorfologicamente definidas, caracterizando-se como formações sedimentares de topos aplainadas de grande extensão territorial, amplamente povoada, com intensa exploração econômica agropecuária, mas com a presença constante de restrições físicas ao uso agrícola, associadas à presença de solos com horizontes coesos em subsuperfície. A presença deste horizonte coeso reduz a profundidade efetiva dos solos, prejudicando a dinâmica da água no perfil e, principalmente, o aprofundamento do sistema radicular, reduzindo as taxas de infiltração de água, criando lençóis freáticos suspensos e que se desenvolvem particularmente sob os Latossolos Amarelos (Latossolos Amarelos) e os Argissolos Amarelos (Podzólicos Amarelos). Assim, a presença destes horizontes em áreas úmidas, pode ser associada a um maior teor de umidade nos solos, que pode ser captada pelo sensor. Devido a sua natureza pedológica e sua localização em sub superfície e sua grande extensão, estes solos demandam grandes recursos para sua efetiva localização e mapeamento. A aplicação de técnicas de processamento digital de imagens nas imagens do sensor ASTER, um sensor experimental e pouco explorado, possibilita a redução de custos, empregados nos levantamentos exploratórios para localização destes horizontes coesos. O principal objetivo deste trabalho foi submeter imagens obtidas através do sensoriamento remoto óptico orbital, do sensor ASTER, a diferentes técnicas de processamento digital de imagens, para assim identificar, reconhecer e caracterizar a presença dos horizontes coesos nos solos dos Tabuleiros Costeiros da Bahia, utilizando como critério identificador, o teor de umidade dos solos. O trabalho foi desenvolvido numa área de aproximadamente 2.475km2, onde está inserida uma área de referência de 29km2, situada no município de Esplanada, onde predominam solos da mesma Classe (Podzólicos Amarelos e Acinzentados) mas diferenciados em unidades que possuem diversos graus de coesão, com textura que varia de arenosa a argilosa. Foi utilizada uma única cena ASTER, sob a qual foi extraída oitenta amostras para determinar a relação entre o teor de umidade dos solos e as diferentes técnicas de processamento digital de imagens. Foram realizadas vinte e seis técnicas de realce (análise componentes principais, Transformação Tasseled Cap, NDVI, NDMI, SAVI e vinte e uma razões entre bandas do sensor ASTER) , além da aplicação de uma classificação supervisionada (método da máxima verossimilhança), com limiar de aceitação de 95%. Os resultados demonstraram que a sétima componente principal é o melhor produto para mapear a presença dos horizontes coesos, por melhor identificar a umidade do solo; o NDMI, o SAVI e a Umidade obtida através da Transformação Tasseled Cap têm um comportamento similar entre si, mas com resultados menos evidentes e entre as razões entre as faixas espectrais testadas, os melhores resultados foram as razões entre as faixas 1 e 8 e entre as faixas 3 e 8. / The Coastal Tableland are units geomorfologicaly defined, characterized by sedimentary formations of smoothed tops of great territorial extension, widely populated, with intense agricultural economic exploration, but with the constant presence of physical restrictions to agricultural use, that are associated to cohesion horizons in subsurface. The presence of this cohesion horizon reduces the soils depth, harming the dynamics of the water in the profile and, mainly, the radicular system of depth, reducing the water infiltration rates and creating suspended sheets particularly under Yellow Latossol and Yellow Podzolic. Thus, the presence of these horizons in humid areas can be associated with higher moisture levels in the soils that can be caught by the sensor. Due to its pedologic nature, sub surface and great extension location, these soil demand great resources for its effective localization and mapping. The application of techniques of image digital processing in the images of the ASTER sensor, an experimental and few explored sensor, turns possible the reduction of costs, used in the exploratory searches for the localization of these cohesion horizons. The main objective of this work was to submit images obtained through the orbital optical remote sensed, of the ASTER sensor, the different image digital processing techniques, in order to identify, to recognize and to characterize the cohesion horizons soil of Coastal Tableland of Bahia, using as identification criteria, the soil moisture contents . The work was developed in an area of 2.475km2 approximately, where an area of reference of 29km2 is inserted, situated in Esplanada city of, where soil of the same class prevail (Yellow and Grey Podzólicos) but differentiated in predominate units that possess diverse cohesion degrees , with texture that varies of sandy the loamy. An only ASTER scene was used, under which it was extracted eighty samples to determine the relationship between the the soil moisture contents and the different images digital images processing techniques. Twenty-six techniques of distinction had been carried through (principal components analysis, Tasseled Cap Transformation, NDVI, NDMI, SAVI and twenty bands ratio on the ASTER sensor bands), beyond the application of a supervised classification (Maximum Likelihood method), with threshold of 95% acceptance. The results had demonstrated that the seventh principal component is the best product to map the cohesion horizons presence and to identify the soil moisture contents; the NDMI, the SAVI and the Wetness obtained through the Tasseled Cap Transformation have a similar behavior, but with less evidences relating the results and, the ratio bands tested, the best results had been those found between bands 1 to 8 and bands 3 to 8.
62

Avaliação do modelo digital de elevação Aster para analise morfometrica de bacias hidrograficas / Evaluation of ASTER digital elevation model for morphometric analysis of drainage basins

Jesus, Nilton de 14 August 2018 (has links)
Orientador: Marcos Cesar Ferreira / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-14T14:48:41Z (GMT). No. of bitstreams: 1 Jesus_Niltonde_D.pdf: 15378244 bytes, checksum: 3da945d16f0c7c0709889469e6205293 (MD5) Previous issue date: 2009 / Resumo: Nos últimos anos, as aplicações da tecnologia SIG têm contribuído às pesquisas geomorfológicas com uma série de novas possibilidades para quantificação das formas de relevo. Ênfase particular tem sido dada à extração de parâmetros morfométricos de bacias hidrográficas, a partir de Modelos Digitais de Elevação (MDE). As aplicações da tecnologia SIG vêm se tornando importante ferramenta para modelagem de processos geomorfodinâmicos, a partir destes parâmetros quantitativos. Neste contexto, a presente pesquisa tem como objetivo apresentar um procedimento para extração da rede de drenagem e dos divisores de bacias hidrográficas, de modo automatizado, a partir do modelo digital de elevação de imagens estereoscópicas do sensor óptico orbital ASTER. Com estes resultados foi calculado parâmetros morfométricos para comparar com parâmetros morfométricos calculados de forma analógica a partir de cartas topográficas do IBGE na escala de 1:50.000. A metodologia utiliza trabalhos no campo da geomorfometria com destaque para a adoção do algoritmo Dinf na definição da rede e de bacias hidrográficas apoiado pelo SIG MapWindow versão 4.4 com plug-in TauDEM (software livre) e pelo SIG Idrisi 32 no cálculo e comparação dos parâmetros morfométricos. Os resultados mostraram que é possível a extração da rede de drenagem e das bacias hidrográficas a partir dos dados do MDE ASTER sem a perda da qualidade para os parâmetros morfométricos tais como, o Índice de Circularidade, Declividade Média, Freqüência de Canais de Primeira Ordem e Fator Topográfico. / Abstract: In the last years, the applications of the Geographical Information System (GIS) technology have been contributing for the geomorphologic researches bringing several new possibilities for quantification landform surface. A particular emphasis has been to the extraction morphometric parameters in watershed supported by Digital Elevation Models (DEM). The applications of the technologies GIS are becoming an important tool for modelling geomorphodinamics processes, based on quantified parameters. In this context, the research focus on the extraction of automated drainage networks and watersheds with DEM from stereoscopic images of the optical sensor orbital ASTER, in order to compare and calculate morphometric parameters with DEM from topographic maps of IBGE, in scale of 1:50.000. This method is based in the field of the geomorphometric with prominence for the adoption of the algorithm Dinf in the determination of drainage network and watershed by GIS MapWindow version 4.4 and plug-in TauDEM (free software) and by GIS Idrisi 32 in the calculation and comparison of the morphometric parameters. It was verified that ASTER DEM extraction morphometric is possible without losing quality for the morphometric parameters as the Circularity Ratio, Medium Slope for watershed, Frequency of First Order Stream and Topography Factor. / Doutorado / Análise Ambiental e Dinâmica Territorial / Doutor em Ciências
63

Towards a Strawberry Harvest Prediction System Using Computer Vision and Pattern Recognition

Apitz, Andreas M 01 June 2018 (has links)
Farmers require advance notice when a harvest is approaching, so they can allocate resources and hire workers as efficiently as possible. Existing methods are subjective and labor intensive, and require the expertise of a professional forecaster. Cal Poly’s EE department has been collaborating with the Cal Poly Strawberry Center to investigate the potential in using digital imaging processing to predict harvests more reliably. This paper shows the progress of that ongoing project, as well as what aspects could still be improved. Three main blocks comprise this system: data acquisition, which obtains and catalogues images of the strawberry plants; computer vision, which extracts information from the images and constructs a time-series model of the field as a whole; and prediction, which uses the field’s history to guess when the most likely harvest window will be. The best method of data acquisition is determined through a decision matrix to be a small autonomous rover. Several challenges specific to images captured via drone, such as fisheye distortion and dirt masking, are examined and mitigated. Using thresholding, the nRGB color space is shown to be the most promising for image segmentation of red strawberries. Data from field 25 at the Cal Poly Strawberry Center is tabulated, analyzed, and compared against industry trends across California. Ultimately, this work serves as a strong benchmark towards a full strawberry yield prediction system.
64

Detekce QR kódů na grafické kartě pro platformu ROS / QR code detection under ROS implemented on the GPU

Hurban, Milan January 2017 (has links)
Tato diplomová práce se zabývá vývojem a implementací algoritmu pro detekci QR kódů s integrací do platformy ROS a výpočty běžícími na grafické kartě. Z rešerše současně dostupných nástrojů a technik je vybrán vhodný postup a algoritmus je napsán jako modul v programovacím jazyce Python, který je snadno integrovatelný do ROS. Ke zprostředkování výpočtů na vícejádrovém hardware, jako jsou grafické karty či vícejádrové procesory, je využita knihovna OpenCL.
65

Měření průměru extrudovaného vlákna s využitím numerických metod zpracování obrazové informace / Numerical Method of Image Processing for Extruded Fiber Diameter Measurement

Vostal, Jiří January 2018 (has links)
This work is focused on extruded fiber diameter measurement problem. For this purpose a procedure has been proposed. This procedure makes use of numerical methods for image processing, which are described in theoretical part of work. The proposed procedure has been processed into single-purpose software and in the final part is assessed its repeatability and reproducibility.
66

Aplikace výpočetních metod v třídění skleněných kamenů / Application of computational methods in classification of glass stones

Lébl, Matěj January 2017 (has links)
Application of computational methods in classification of glass stones Bc. Matěj Lébl Abstrakt: The goal of this thesis is to employ mathematical image processing methods in automatic quality control of glass jewellery stones. The main math- ematical subject is a matrix of specific attributes representing digital image of the studied products. First, the thesis summarizes mathematical definition of digital image and some standard image processing methods. Then, a complete solution to the considered problem is presented. The solution consists of stone localization within the image followed by analysis of the localized area. Two lo- calization approaches are presented. The first is based on the matrix convolution and optimized through the Fourier transform. The second uses mathematical methods of thresholding and median filtering, and data projection into one di- mension. The localized area is analyzed based on statistical distribution of the stone brightness. All methods are implemented in the MATLAB environment. 1
67

Internal structure characterization of asphalt concrete using x-ray computed tomography.

Onifade, Ibrahim January 2013 (has links)
This study is carried out to develop the workflow from image acquisition to numerical simulation for asphalt concrete (AC) microstructure. High resolution computed tomography (CT) images are acquired and the image quality is improved using digital image processing (DIP). Non-uniform illumination which results in inaccurate phase segmentation is corrected by applying an illumination profile to correct the background and flat-fields in the image. Distance map based watershed segmentation is used to accurately segment the phases and separate the aggregates. Quantitative analysis of the microstructure is used to determine the phase volumetric relationship and aggregates characteristics. The results of the phase reconstruction and internal structure quantification using this procedure shows a very high level of reliability. Numerical simulations are carried out in Two dimensions (2D) and Three dimensions (3D) on the processed AC microstructure. Finite element analysis (FEM) is used to capture the strength and deformation mechanisms of the AC microstructure. The micromechanical behaviour of the AC is investigated when it is considered as a continuum and when considered as a multi-phase model. The results show that the size and arrangement of aggregates determines the stress distribution pattern in the mix.
68

Automatic Identification and Tracking of Retraction Fibers in Time-Lapse Microscopy

Shaikh, Meher Talat 12 March 2010 (has links) (PDF)
Digital image processing is widely used in the field of time-lapse microscopy and biological research to provide statistical data of cellular dynamics. The data can provide more comprehensive understanding of the molecular phenomenon. Further, digital image processing enables rapid and consistent quantification of qualitative observations. The image processing model examined here provides a study to identify structures called retraction fibers (RFs) that are formed during epithelial-mesenchymal transition (EMT) [1], an important developmental process which also occurs during cancer metastasis. Quantifying RF formation is an important task for biologists studying cellular regulation of EMT. This thesis work uses digital image processing and computer vision algorithms to detect and track each RF in image sequences of cells undergoing EMT that are captured using time-lapse microscopy. The algorithms isolate the RFs with reasonable precision. Statistical information is generated about these automatically detected RFs, such as the number formed during a particular time window, lifetime of each, and their geometric dimension. This information can in turn be used by biologists to quantitatively measure the extent of EMT under different test conditions. Biologists feel that the information thus obtained may help clarify the molecular interactions of cell migration and will aid in developing methods of preventing cancer metastasis. Experimental results show that this methodology has significant potential in helping biologists determine RF behavior during EMT.
69

Analytical and experimental investigations of dam-break flows in triangular channels with wet-bed conditions

Wang, B., Liu, X., Zhang, J., Guo, Yakun, Chen, Y., Peng, Y., Liu, W., Yang, S., Zhang, F. 28 July 2020 (has links)
Yes / Based on the method of characteristics, an analytical solution for the one-dimensional shallow-water equations is developed to simulate the instantaneous dam-break flows propagating down a triangular wet bed channel in this study. The internal relationships between the hydraulic properties associated with the dam-break flow are investigated through the comparisons with the well-known analytical solutions for rectangular channels. Meanwhile, laboratory experiments are conducted in a prismatic, horizontal and smooth flume with a triangular cross-section. The non-intrusive digital image processing is applied for obtaining water surface profiles and stage hydrographs. Results show that the dam-break flow propagation depends on the dimensionless parameter defined as the ratio of initial tailwater depth over reservoir head. has significant effect on the dam-break wave in the downstream flooded area. For , the water surface profiles in the reservoir for different at a given time remains similar. For ≥ 0.5, extra negative waves occur in the reservoir, leading to the water surface undulations. Undular bores are generated at the dam site and propagate downstream. Time evolution of dam-break flows under three different reservoir heads is similar for the same . The inception of water surface profile change is earlier when the reservoir head is larger. The analytical model shows satisfactory agreement with the experimental results though some errors exist between the analytical solution and measurements due to the formation of extra negative waves, jet and undular bores. The similarities and discrepancies between the hydraulics in the triangular and rectangular channels are identified analytically in terms of the profiles of water depth, velocity, discharge, bore height and wave-front celerity with . The presented solution could be applied to predict the effect of wet bed condition on the dam-break wave in triangular channels, while laboratory measurement data could be used for validating analytical and numerical models. / National Natural Science Foundation of China (Grant No: 51879179), Sichuan Science and Technology Program (No. 2019JDTD0007) and Open Fund from the State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University (SKHL1809)
70

Experimental investigation on the effects of bed slope and tailwater on dam-break flows

liu, Wenjun, Wang, Bo, Guo, Yakun, Zhang, Jianmin, Chen, Yunliang 03 July 2020 (has links)
Yes / Understanding of the characteristics of dam-break flows moving along a sloping wet bed can help to timely issue flood warning and risk mitigation. In this study, laboratory experiments are carried out in a large flume for a wide range of upstream water depth, bed slopes and tailwater depth. The water level is recorded and processed to calculate the mean velocity and wave celerity. Results show that the increase of the bed slope will significantly accelerate the wave-front celerity for the downstream dry bed, while the negative wave celerity will decrease. When water depth ratio α ≥ 0.3 (defined as the ratio of initial downstream water depth over the upstream water depth of dam), there are extra negative waves propagating towards the reservoir area after the flow has developed for a period of time. When α ≥ 0.6, there are the Favre waves propagating downstream. The water level and the mean velocity fluctuate due to the influence of the extra negative waves and the Favre waves. Such fluctuant frequency increases with the increase of the water depth ratio. The empirical formulas are obtained for the celerity of the first extra negative wave and the first downstream wave. The variation of wave-front height is very similar under three bed slopes investigated in this study, while the maximum wave-front height occurs when α = 0.2. The present study broadens the understanding of the effects of the bed slope and the tailwater level on the movement of the dam-break flows. Furthermore, experimental results are also compared with some analytical solutions. The validity of the assumptions made during the development of these analytical solutions and their limitations are discussed by comparing with the experimental measurements. / The National Natural Science Foundation of China (Grant No: 51879179), the Open Fund from the State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University (SKHL1809) and Sichuan Science and Technology Program (No. 2019JDTD0007).

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