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

Estimating ground-level PM2.5 in Texas from remote sensing satellite data with interpolation and regression methods

Jiang, Xiaoyan 2009 August 1900 (has links)
The integration of remote sensing satellite data in air quality monitoring system at a regional scale is an important method to provide high spatial / temporal resolution information. This work focuses on estimating high spatial / temporal resolution ground-level information about particulate matter with aerodynamic diameters less than 2.5 um (PM2.5), with the utilization of MODIS aerosol optical thickness (AOT) data and meteorological data. Several missing data reconstruction techniques including Bayesian inversion, regularization and prediction-error filter are employed to estimate PM2.5 from satellite data. The results show that several direct missing data interpolation methods have the capability to estimate some distinctive features on the basis of available ground-based measurements, while the PEF method tends to generate more information with the aid of satellite AOT information. In addition to interpolation methods, general linear regression methods are used to predict ground-level PM2.5 with the consideration of other factors that have been shown to play an important role in predictions. Ordinary Least Square (OLS) method, when natural log taken on dependent and independent variables, is able to reduce the violation of homoscedasticity. The scatterplot of predicted and measured PM2.5 shows a strong correlation over the validation region, indicating the ability of the regression model to predict PM2.5. Weighted Least Square (WLS) method also has advantage in improving homoscedasticity. The predicted and measured PM2.5 has a relatively high correlation. / text
2

Performance of regional atmospheric error models for NRTK in GPSnet and the implementation of a NRTK system

Wu, Suquin, s3102813@student.rmit.edu.au January 2009 (has links)
Many high-accuracy regional GPS continuously operating reference (CORS) networks have been established globally. These networks are used to facilitate better positioning services, such as high accuracy real-time positioning. GPSnet is the first state-wide CORS network in Australia. In order to maximize the benefits of the expensive CORS geospatial infrastructure, the state of Victoria in collaboration with three universities (RMIT University, the University of NSW and the University of Melbourne) embarked on research into regional atmospheric error modelling for Network-based RTK (NRTK) via an Australian Research Council project in early 2005. The core of the NRTK technique is the modelling of the spatially-correlated errors. The accuracy of the regional error model is a determining factor for the performance of NRTK positioning. In this research, a number of error models are examined and comprehensively analysed. Among them, the following three models are tested: 1) the Linear Interpolation Method (LIM); 2) the Distance-Based interpolation method (DIM); and 3) the Low-order surface model (LSM). The accuracy of the three models is evaluated using three different observation sessions and a variety of network configurations of GPSnet. Results show that the LIM and DIM can be used to significantly reduce the double-differenced (DD) residuals (up to 60% improvement), and the LIM is slightly better than the DIM (most at mm level). However the DD residuals with the LSM corrections are, in some cases, not only much worse than that of the LIM and DIM but also even must greater/worse than the DD residuals without any corrections applied at all. This indicates that there are no advantages by using the LSM for the error modelling for NRTK in GPSnet, even though it is the most commonly used method by researchers. The performance difference of the LIM for different GPSnet configurations is also tested. Results show that in most cases, the performance difference mainly caused by the number of reference stations used is not significant. This implies that more redundant reference stations may not contribute much to the accuracy improvement of the LIM. However, it may mitigate the station specific errors (if any). The magnitude of the temporal variations of both the tropospheric and ionospheric effects in GPSnet observations is also investigated. Test results suggest that the frequency of generating and transmitting the tropospheric corrections should not be significantly different from that for the ionospehric corrections. Thus 1Hz frequency (i.e. once every second) is recommended for the generation and transmission for both types of the atmospheric corrections for NRTK in GPSnet. The algorithms of the NRTK software package used are examined and extensive analyses are conducted. The performance and limitation of the NRTK system in terms of network ambiguity resolution are assessed. The methodology for generating virtual reference station (VRS) observations in the system is presented. The validation of the algorithms for the generated VRS observations is undertaken. It is expected that this research is significant for both the selection of regional error models and the implementation of the NRTK technique in GPSnet or in the Victorian region.
3

ACCURATE APPROXIMATION OF UNSTRUCTURED GRID INTO REGULAR GRID WITH COMPLEX BOUNDARY HANDLING

Dana M El Rushaidat (11777354) 03 December 2021 (has links)
<p>Computational Fluid Dynamic (CFD) simulations often produce datasets defined over unstructured grids with solid boundaries. Though unstructured grids allow for the flexible representation of this geometry and the refinement of the grid resolution, they suffer from high storage cost, non-trivial spatial queries, and low reconstruction smoothness. Rectilinear grids, in contrast, have a negligible memory footprint and readily support smooth data reconstruction, though with reduced geometric flexibility.</p><p>This thesis is concerned with the creation of accurate reconstruction of large unstructured datasets on rectilinear grids with the capability of representing complex boundaries. We present an efficient method to automatically determine the geometry of a rectilinear grid upon which a low-error data reconstruction can be achieved with a given reconstruction kernel. Using this rectilinear grid, we address the potential ill-posedness of the data fitting problem, as well as the necessary balance between smoothness and accuracy, through a bi-level smoothness regularization. To tackle the computational challenge posed by very large input datasets and high-resolution reconstructions, we propose a block-based approach that allows us to obtain a seamless global approximation solution from a set of independently computed sparse least-squares problems. </p><p></p><p>We endow the approximated rectilinear grid with boundary handling capabilities that allows for accommodating challenging boundaries while supporting high-order reconstruction kernels. Results are presented for several 3D datasets that demonstrate the quality of the visualization results that our reconstruction enables, at a greatly reduced computational and memory cost. Our data representation enjoys all the benefits of conventional rectilinear grids while addressing their fundamental geometric limitations.</p>
4

Geoestatística e geoprocessamento aplicados à tomada de decisão agroambiental em um sistema de produção de leite a pasto intensivo / Geostatistics and geoprocessing in decision making agroenvironmental in a system of milk production intensive grazing

Karoline Eduarda Lima Santos 21 September 2017 (has links)
Movido pelo crescimento populacional, a visão de sistemas sustentáveis tem despertado a atenção de diversos setores. Sendo um dos principais domínios economicamente ativo do país, a agropecuária vem buscando meios para se adequar a essa realidade. Nesse contexto, surgem as Boas Práticas Agropecuárias, das quais pode-se citar a Agricultura de Precisão, o pastejo rotacionado e o manejo ambiental, os quais se implementados em conjunto proporcionam um melhor gerenciamento da área de interesse. Assim, objetivou-se, aplicar conceitos de geoestatística e geoprocessamento para a obtenção de zonas de manejo de uma área de pastagem de capim Tanzânia, em São Carlos - SP, e delimitação de unidades de manejo para aplicação de calagem e adubação, com base no melhor método de interpolação. Com os resultados de análise de solo foram realizadas análises geoestatísticas para avaliação da dependência espacial dos atributos químicos, e a Validação Cruzada dos modelos adotados. Os mapas foram obtidos pelo método de interpolação por Krigagem Ordinária e a definição das zonas de manejo foi realizada por meio de lógica fuzzy. A partir dos mapas dos parâmetros químicos do solo gerou-se o mapa de zonas de manejo resultando em cinco zonas sendo: 0,02 ha (1,2% da área total) considerada como \"muito baixa\" fertilidade; 0,3 ha (18%) \"baixa\" fertilidade; 0,75 ha (44%) como \"média\" fertilidade; 0,55 ha (32%) como \"alta\" fertilidade e, 0,08 ha (4,8%) como \"muita alta\" fertilidade. A comparação dos métodos de interpolação demonstrou que a Krigagem Ordinária foi a melhor metodologia para o estudo. A geoestatística e o geoprocessamento demonstraram ser técnicas que auxiliam nas decisões estratégicas e complexas em relação ao gerenciamento do sistema de produção agrícola. / Movin by population growth, the vision of sustainable systems has attracted the attention of various sectors. Being one of the main areas economically active of the country, agriculture has been seeking ways to adapt to this reality. In this context, emerge the Good Farming Practices, which among them we can mention the Agriculture of Precision, the rotate pasture and environmental management, which if implemented together will provide a better management of the area of interest. The present study aimed to apply the concepts of geostatistics and gis to obtain areas of management of an area of pasture grass, Tanzania, São Carlos &#8211; SP, and delimitation of management units for the application of liming and fertilization, based on the best interpolation method. With the analysis results of the soil analyses were performed geo-statistical for evaluation of the dependence on the spatial attributes of chemicals. The maps were obtained by the method of interpolation by Kriging Ordinary and the definition of zones for the management was performed by fuzzy logic. From the maps of chemical parameters of the soil has resulted from the management zone map, resulting in five areas being: 0.02 ha (1.2% of total area) regarded as \"very low\" fertility; and 0.3 ha (18%) \"low\" fertility; 0.75 ha (44%) as \"average\" fertility; 0.55 ha (32%) as \"high\" fertility and, 0.08 ha (4.8%) as \"very high\" fertility. The comparison of the interpolation methods showed that Kriging Ordinary was the best methodology for the study. The geostatistics and gis have proved to be techniques that help with strategic and complex decisions in relation to the management of the agricultural production system.
5

Geoestatística e geoprocessamento aplicados à tomada de decisão agroambiental em um sistema de produção de leite a pasto intensivo / Geostatistics and geoprocessing in decision making agroenvironmental in a system of milk production intensive grazing

Santos, Karoline Eduarda Lima 21 September 2017 (has links)
Movido pelo crescimento populacional, a visão de sistemas sustentáveis tem despertado a atenção de diversos setores. Sendo um dos principais domínios economicamente ativo do país, a agropecuária vem buscando meios para se adequar a essa realidade. Nesse contexto, surgem as Boas Práticas Agropecuárias, das quais pode-se citar a Agricultura de Precisão, o pastejo rotacionado e o manejo ambiental, os quais se implementados em conjunto proporcionam um melhor gerenciamento da área de interesse. Assim, objetivou-se, aplicar conceitos de geoestatística e geoprocessamento para a obtenção de zonas de manejo de uma área de pastagem de capim Tanzânia, em São Carlos - SP, e delimitação de unidades de manejo para aplicação de calagem e adubação, com base no melhor método de interpolação. Com os resultados de análise de solo foram realizadas análises geoestatísticas para avaliação da dependência espacial dos atributos químicos, e a Validação Cruzada dos modelos adotados. Os mapas foram obtidos pelo método de interpolação por Krigagem Ordinária e a definição das zonas de manejo foi realizada por meio de lógica fuzzy. A partir dos mapas dos parâmetros químicos do solo gerou-se o mapa de zonas de manejo resultando em cinco zonas sendo: 0,02 ha (1,2% da área total) considerada como \"muito baixa\" fertilidade; 0,3 ha (18%) \"baixa\" fertilidade; 0,75 ha (44%) como \"média\" fertilidade; 0,55 ha (32%) como \"alta\" fertilidade e, 0,08 ha (4,8%) como \"muita alta\" fertilidade. A comparação dos métodos de interpolação demonstrou que a Krigagem Ordinária foi a melhor metodologia para o estudo. A geoestatística e o geoprocessamento demonstraram ser técnicas que auxiliam nas decisões estratégicas e complexas em relação ao gerenciamento do sistema de produção agrícola. / Movin by population growth, the vision of sustainable systems has attracted the attention of various sectors. Being one of the main areas economically active of the country, agriculture has been seeking ways to adapt to this reality. In this context, emerge the Good Farming Practices, which among them we can mention the Agriculture of Precision, the rotate pasture and environmental management, which if implemented together will provide a better management of the area of interest. The present study aimed to apply the concepts of geostatistics and gis to obtain areas of management of an area of pasture grass, Tanzania, São Carlos &#8211; SP, and delimitation of management units for the application of liming and fertilization, based on the best interpolation method. With the analysis results of the soil analyses were performed geo-statistical for evaluation of the dependence on the spatial attributes of chemicals. The maps were obtained by the method of interpolation by Kriging Ordinary and the definition of zones for the management was performed by fuzzy logic. From the maps of chemical parameters of the soil has resulted from the management zone map, resulting in five areas being: 0.02 ha (1.2% of total area) regarded as \"very low\" fertility; and 0.3 ha (18%) \"low\" fertility; 0.75 ha (44%) as \"average\" fertility; 0.55 ha (32%) as \"high\" fertility and, 0.08 ha (4.8%) as \"very high\" fertility. The comparison of the interpolation methods showed that Kriging Ordinary was the best methodology for the study. The geostatistics and gis have proved to be techniques that help with strategic and complex decisions in relation to the management of the agricultural production system.
6

Interpolace obrazových bodů / Pixel Interpolation Methods

Mintěl, Tomáš January 2009 (has links)
This master's thesis deals with acceleration of pixel interpolation methods using the GPU and NVIDIA (R) CUDA TM architecture. Graphic output is represented by a demonstrational application for geometrical image transforms using chosen interpolation method. Time critical parts of the code are moved on the GPU and executed in parallel. There are used highly optimized routines from the OpenCV library, made by the Intel company for an image and video processing.
7

Distância entre passadas da colhedora com monitor de colheita nos mapas de produtividade e teor de água na cultura do milho / The distance among combine step with yield monitor in the yield and moisture maps in the culture of the corn

Bazzi, Claudio Leones 25 January 2007 (has links)
Made available in DSpace on 2017-05-12T14:46:54Z (GMT). No. of bitstreams: 1 Claudio Leones Bazzi.pdf: 3343114 bytes, checksum: 3fa53d5262ab876ffddc75c68048a730 (MD5) Previous issue date: 2007-01-25 / The precision agriculture comes in the last years enlarging its application in the country, seeking the increase of the productivity and profitability, also reducing the environmental impact with the appropriate application of fertilizers and agricultural inputs. The impediment for larger expansion of the technology is mainly the high cost of the equipments to be used. The generation of yield maps is the phase that presents larger execution easiness inside of the cycle of AP. However when several combines are working in a certain area, not always it is possible to have monitors in each one of them. In this context this work had as objective finds the step maximum number that it can be eliminated by the combine not equipped with yield monitor without quality loss in the yield and moisture maps generated. It was also looked for to accomplish a comparison among the interpolation methods inverse square root and Kriging. In the comparison between the simulated maps and the original, the coefficient of relative deviation was used - CDR and the index kappa. He/she was proven that the eliminated last number reduces the precision of the maps in both interpolation methods. The amount monitors that it should be had in a combine group, are relative at the level of precision that one want to have. The monitored combine should be inserted so that the samples are collected in an uniform way by the whole area to be crop. / A agricultura de precisão (AP) vem, nos últimos anos, ampliando sua aplicação no País, a fim de aumentar a produtividade e lucratividade, bem como diminuir o impacto ambiental com a aplicação adequada de insumos agrícolas. O entrave para a maior expansão da tecnologia está principalmente no elevado custo dos equipamentos a serem utilizados. A geração de mapas de produtividade é a fase que apresenta maior facilidade de execução dentro do ciclo da AP. Entretanto, quando várias colhedoras estão colhendo em uma determinada área, nem sempre é possível a presença de monitores de colheita em cada uma delas. Nesse contexto, este trabalho teve como objetivo encontrar o número máximo de passadas que podem ser eliminadas pela utilização de colhedoras não equipadas com monitor de colheita sem que haja perda de qualidade nos mapas de produtividade e de teor de água gerados. Buscou-se também realizar um comparativo entre os métodos de interpolação inverso da distância ao quadrado e Krigagem . Na comparação entre os mapas simulados e o original, utilizaram-se o coeficiente de desvio relativo CDR - e o índice kappa. Comprovou-se que o número de passadas eliminadas diminui a precisão dos mapas em ambos métodos de interpolação. A quantidade de monitores que deve haver em um conjunto de colhedoras é relativa ao nível de precisão que se deseja ter, devendo-se intercalá-las de maneira que as amostras sejam coletadas uniformemente por toda a área a ser colhida.
8

Distância entre passadas da colhedora com monitor de colheita nos mapas de produtividade e teor de água na cultura do milho / The distance among combine step with yield monitor in the yield and moisture maps in the culture of the corn

Bazzi, Claudio Leones 25 January 2007 (has links)
Made available in DSpace on 2017-07-10T19:23:41Z (GMT). No. of bitstreams: 1 Claudio Leones Bazzi.pdf: 3343114 bytes, checksum: 3fa53d5262ab876ffddc75c68048a730 (MD5) Previous issue date: 2007-01-25 / The precision agriculture comes in the last years enlarging its application in the country, seeking the increase of the productivity and profitability, also reducing the environmental impact with the appropriate application of fertilizers and agricultural inputs. The impediment for larger expansion of the technology is mainly the high cost of the equipments to be used. The generation of yield maps is the phase that presents larger execution easiness inside of the cycle of AP. However when several combines are working in a certain area, not always it is possible to have monitors in each one of them. In this context this work had as objective finds the step maximum number that it can be eliminated by the combine not equipped with yield monitor without quality loss in the yield and moisture maps generated. It was also looked for to accomplish a comparison among the interpolation methods inverse square root and Kriging. In the comparison between the simulated maps and the original, the coefficient of relative deviation was used - CDR and the index kappa. He/she was proven that the eliminated last number reduces the precision of the maps in both interpolation methods. The amount monitors that it should be had in a combine group, are relative at the level of precision that one want to have. The monitored combine should be inserted so that the samples are collected in an uniform way by the whole area to be crop. / A agricultura de precisão (AP) vem, nos últimos anos, ampliando sua aplicação no País, a fim de aumentar a produtividade e lucratividade, bem como diminuir o impacto ambiental com a aplicação adequada de insumos agrícolas. O entrave para a maior expansão da tecnologia está principalmente no elevado custo dos equipamentos a serem utilizados. A geração de mapas de produtividade é a fase que apresenta maior facilidade de execução dentro do ciclo da AP. Entretanto, quando várias colhedoras estão colhendo em uma determinada área, nem sempre é possível a presença de monitores de colheita em cada uma delas. Nesse contexto, este trabalho teve como objetivo encontrar o número máximo de passadas que podem ser eliminadas pela utilização de colhedoras não equipadas com monitor de colheita sem que haja perda de qualidade nos mapas de produtividade e de teor de água gerados. Buscou-se também realizar um comparativo entre os métodos de interpolação inverso da distância ao quadrado e Krigagem . Na comparação entre os mapas simulados e o original, utilizaram-se o coeficiente de desvio relativo CDR - e o índice kappa. Comprovou-se que o número de passadas eliminadas diminui a precisão dos mapas em ambos métodos de interpolação. A quantidade de monitores que deve haver em um conjunto de colhedoras é relativa ao nível de precisão que se deseja ter, devendo-se intercalá-las de maneira que as amostras sejam coletadas uniformemente por toda a área a ser colhida.
9

Vliv prostorového rozložení sněhu na průběh povodní / Influence of spatial snow distribution on flood course

Kučerová, Dana January 2010 (has links)
For the purpose of hydrological forecasting on mountains' and sub-mountains' rivers is important knowledge of distribution of snow water equivalent in the watershed. Submitted thesis therefore deals with comparison of 9 interpolation methods in terms of quality of their forecasting when predicting snow depth and snow water equivalent in watershed Bystřice (127,6 km2 ), which is situated in the northwest of Bohemia in the Ore mountains. Point data of snow depth and snow water equivalent used in interpolation were sampled during an off- road measuring in 17. 2. 2010 at the 14 snow sampling locations. The interpolation methods were: (1) Thiessen's polygons, (2) inverse distance weighting, (3) global polynomial (4) local polynomial (5) radial basis functions, (6) ordinary kriging, (7) cokriging, (8) residual kriging and (9) orographic interpolation. Independent variable-altitude used in the calculation of snow depth and snow water equivalent was used only in the last three listed methods. Predictive ability of interpolation methods was evaluated by using cross-validation and visual comparison of predicted maps. The best prediction ability was provided by residual kriging and orographic interpolation. The geostatistical methods were next in the order. The method of Thiessen's polygons and inverse distance...
10

Comparison of heat maps showing residence price generated using interpolation methods / Jämförelse av färgdiagram för bostadspriser genererade med hjälp av interpolationsmetoder

Wong, Mark January 2017 (has links)
In this report we attempt to provide insights in how interpolation can be used for creating heat maps showing residence prices for different residence markets in Sweden. More specifically, three interpolation methods are implemented and are then used on three Swedish residence markets. These three residence markets are of varying characteristics such as size and residence type. Data of residence sales and the physical definitions of the residence markets were collected. As residence sales are never identical, residence sales were preprocessed to make them comparable. For comparison, a so-called external predictor was used as an extra parameter for the interpolation method. In this report, distance to nearest public transportation was used as an external predictor. The interpolated heat maps were compared and evaluated using both quantitative and qualitative approaches. Results show that each interpolation method has its own strengths and weaknesses, and that using an external predictor results in better heat maps compared to only using residence price as predictor. Kriging was found to be the most robust method and consistently resulted in the best interpolated heat maps for all residence markets. On the other hand, it was also the most time-consuming interpolation method. / Den här rapporten försöker ge insikter i hur interpolation kan användas för att skapa färgdiagram över bostadspriser för olika bostadsmarknader i Sverige. Mer specifikt implementeras tre interpolationsmetoder som sedan används på tre olika svenska bostadsmarknader. Dessa tre bostadsmarknader är av olika karaktär med hänsyn till storlek och bostadstyp. Bostadsförsäljningsdata och de fysiska definitionerna för bostadsmarknaderna samlades in. Eftersom bostadsförsäljningar aldrig är identiska, behandlas de först i syfte att göra dem jämförbara. En extern indikator, vilket är en extra parameter för interpolationsmetoder, undersöktes även. I den här rapporten användes avståndet till närmaste kollektiva transportmedel som extern indikator. De interpolerade färgdiagrammen jämfördes och utvärderades både med en kvantiativ och en kvalitativ metod. Resultaten visar att varje interpolationsmetod har sina styrkor och svagheter och att användandet av en extern indikator alltid renderade i ett bättre färgdiagram jämfört med att endast använda bostadspris som indikator. Kriging bedöms vara den mest robusta interpolationsmetoden och interpolerade även de bästa färgdiagrammen för alla bostadsmarknader. Samtidigt var det även den mest tidskrävande interpolationsmetoden.

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