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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

Fluid Molecular Layers at the Interface between Mica and 2D Materials Investigated by Optical Spectroscopy and Scanning Force Microscopy

Lin, Hu 06 July 2022 (has links)
Die Art der zwischen den 2D-Materialien und den festen Substraten eingeschlossenen Wasserschichten ist umstritten, sowie auch ihr Einfluss auf die Eigenschaften der 2D-Materialien. In-situ-Rasterkraftmikroskopie (SFM) wurde eingesetzt, um den Benetzungsprozess von Wasser an der Grenzfläche zwischen trockenem graphen- und molybdändisulfid (MoS2)- und Glimmer zu visualisieren. In-situ Raman- und Photolumineszenzmessungen (PL) wurden durchgeführt, um zu untersuchen, wie sich die Ladungsdotierung von Graphen und die Dehnung von Graphen und MoS2 bei der Benetzung verändern. SFM-Ergebnisse zeigen, dass Wassermoleküle, die die trockene Grenzfläche benetzen, bei hoher relativer Luftfeuchtigkeit eine homogene monomolekulare Schicht ausbilden. Aus Raman-Messungen kann man schließen, dass die Wasserschicht vorhandenen Ladungstransfer an der trockenen Grenzfläche blockiert, während eine Schicht aus Ethanolmolekülen dafür nicht ausreicht. Der Austausch von Ethanol gegen Wasser und umgekehrt ermöglicht eine reversible Umschaltung des Ladungstransfers an der Grenzfläche. Dehnungsänderungen von 2D-Materialien auf Glimmer mit eingeschlossenen Flüssigkeitsschichten wird in dieser Arbeit durch Dehnung eines Glimmersubstrats mit darauf exfoliertem 2D-Material untersucht. Die dadurch induzierte Dehnung in Graphen und MoS2 wird durch die Analyse der Veränderungen in den Raman- bzw. PL-Spektren ermittelt. Dabei kann eine Dehnungsrelaxation in Graphen beobachtet werden, die sich von einer „Stick-Slip-Bewegung“ bei trockener Grenzfläche zu viskosem Relaxationsverhalten verändert, wenn Wasser in die Grenzfläche interkaliert. Im Gegensatz dazu findet man in MoS2 unabhängig von der Hydratation keine viskose Relaxation. / The nature of the water layers confined between 2D materials and solid substrates is disputed, also their influences on properties of 2D materials are in debate. I employ In-situ scanning force microscopy (SFM) to visualize wetting of water at the dry graphene-/molybdenum disulfide (MoS2) - mica interface. In-situ Raman and photoluminescence (PL) measurements probe charge-doping and strain change of graphene and MoS2 upon wetting. SFM results show that water molecules wetting the dry interface form a monomolecular layer at high relative humidity (RH). Raman results imply that the water layer blocks charge transfer from mica to graphene, while an ethanol monolayer allows for it. Strain changes of both 2D materials on mica with confined liquid layers are investigated by stretching a mica substrate with the 2D material exfoliated on it. The strain induced in graphene and MoS2 is inferred by analyzing changes in Raman and PL spectra, respectively. Strain relaxation in graphene changes from stick-slip for dry interface to viscous when intercalated by water. In contrast, there is no viscous relaxation in MoS2 regardless of hydration.
32

Uso de nubes de puntos 3D para identificación y caracterización de familias de discontinuidades planas en afloramientos rocosos y evaluación de la calidad geomecánica

Riquelme, Adrián 25 September 2015 (has links)
En este trabajo se estudia el uso de las nubes de puntos en 3D, es decir, un conjunto de puntos en un sistema de referencia cartesiano en R3, para la identificación y caracterización de las discontinuidades que afloran en un macizo rocoso y su aplicación al campo de la Mecánica de Rocas. Las nubes de puntos utilizadas se han adquirido mediante tres técnicas: sintéticas, 3D laser scanner y la técnica de fotogrametría digital Structure From Motion (SfM). El enfoque está orientado a la extracción y caracterización de familias de discontinuidades y su aplicación a la evaluación de la calidad de un talud rocoso mediante la clasificación geomecánica Slope Mass Rating (SMR). El contenido de la misma está dividido en tres bloques, como son: (1) metodología de extracción de discontinuidades y clasificación de la nube de puntos 3D; (2) análisis de espaciados normales en nubes de puntos 3D; y (3) análisis de la evaluación de la calidad geomecánica de taludes rocoso mediante la clasificación geomecánica SMR a partir de nubes de puntos 3D. La primera línea de investigación consiste en el estudio de las nubes de puntos 3D con la finalidad de extraer y caracterizar las discontinuidades planas presentes en la superficie de un macizo rocoso. En primer lugar, se ha recopilado información de las metodologías existentes y la disponibilidad de programas para su estudio. Esto motivó la decisión de investigar y diseñar un proceso de clasificación novedoso, que muestre todos los pasos para su programación e incluso ofreciendo el código programado a la comunidad científica bajo licencia GNU GPL. De esta forma, se ha diseñado una novedosa metodología y se ha programado un software que analiza nubes de puntos 3D de forma semi-automática, permitiendo al usuario interactuar con el proceso de clasificación. Dicho software se llama Discontinuity Set Extractor (DSE). El método se ha validado empleando nubes de puntos sintéticas y adquiridas con 3D laser scanner. En primer lugar, este código analiza la nube de puntos efectuando un test de coplanaridad para cada punto y sus vecinos próximos para, a continuación, calcular el vector normal de la superficie en el punto estudiado. En segundo lugar, se representan los polos de los vectores normales calculados en el paso previo en una falsilla estereográfica. A continuación se calcula la densidad de los polos y los polos con mayor densidad o polos principales. Estos indican las orientaciones de la superficie más representadas, y por tanto las familias de discontinuidades. En tercer lugar, se asigna a cada punto una familia en dependencia del ángulo formado por el vector normal del punto y el de la familia. En este punto el usuario puede visualizar la nube de puntos clasificada con las familias de discontinuidades que ha determinado para validar el resultado intermedio. En cuarto lugar, se realiza un análisis cluster en el que se determina la agrupación de puntos según planos para cada familia (clusters). A continuación, se filtran aquellos que no tengan un número de puntos suficiente y se determina la ecuación de cada plano. Finalmente, se exportan los resultados de la clasificación a un archivo de texto para su análisis y representación en otros programas. La segunda línea de investigación consiste en el estudio del espaciado entre discontinuidades planas que afloran en macizos rocosos a partir de nubes de puntos 3D. Se desarrolló una metodología de cálculo de espaciados a partir de nubes de puntos 3D previamente clasificadas con el fin de determinar las relaciones espaciales entre planos de cada familia y calcular el espaciado normal. El fundamento novedoso del método propuesto es determinar el espaciado normal de familia basándonos en los mismos principios que en campo, pero sin la restricción de las limitaciones espaciales, condiciones de inseguridad y dificultades inherentes al proceso. Se consideraron dos aspectos de las discontinuidades: su persistencia finita o infinita, siendo la primera el aspecto más novedoso de esta publicación. El desarrollo y aplicación del método a varios casos de estudio permitió determinar su ámbito de aplicación. La validación se llevó a cabo con nubes de puntos sintéticas y adquiridas con 3D laser scanner. La tercera línea de investigación consiste en el análisis de la aplicación de la información obtenida con nubes de puntos 3D a la evaluación de la calidad de un talud rocoso mediante la clasificación geomecánica SMR. El análisis se centró en la influencia del uso de orientaciones determinadas con distintas fuentes de información (datos de campo y técnicas de adquisición remota) en la determinación de los factores de ajuste y al valor del índice SMR. Los resultados de este análisis muestran que el uso de fuentes de información y técnicas ampliamente aceptadas pueden ocasionar cambios en la evaluación de la calidad del talud rocoso de hasta una clase geomecánica (es decir, 20 unidades). Asimismo, los análisis realizados han permitido constatar la validez del índice SMR para cartografiar zonas inestables de un talud. Los métodos y programas informáticos desarrollados suponen un importante avance científico para el uso de nubes de puntos 3D para: (1) el estudio y caracterización de las discontinuidades de los macizos rocosos y (2) su aplicación a la evaluación de la calidad de taludes en roca mediante las clasificaciones geomecánicas. Asimismo, las conclusiones obtenidas y los medios y métodos empleados en esta tesis doctoral podrán ser contrastadas y utilizados por otros investigadores, al estar disponibles en la web del autor bajo licencia GNU GPL.
33

Análise custo-benefício do manejo florestal sustentável em Roraima

Paiva, Natalino Araújo January 2011 (has links)
Esta dissertação aborda a análise custo-benefício (ACB) em manejo florestal sustentável (MFS) em Roraima, Unidade da Federação pertencente à Amazônia Legal que assim como os outros Estados sofrem com a falta de alternativas econômicas frente à pressão regional e internacional de não uso dos recursos da floresta. Por essa razão, este trabalho, procurou estudar a viabilidade da atividade de manejo florestal sustentável (MFS), a fim de subsidiar futuros empreendimentos que sejam ao mesmo tempo economicamente viável e ambientalmente corretos. Para alcançar tal objetivo foi necessário expor exaustivamente a corrente do desenvolvimento sustentável, tais como, sua origem, o contexto histórico, seus conceitos, tratados e convenções que asseguraram juridicamente o pensamento conservacionista. Além disso, foi preciso embasamento na Ciência Econômica, com o conteúdo transversal sobre a Curva de Kuznets, conceito de bens públicos e as implicâncias das externalidades no custo ambiental, bem como de contribuições de economistas como Pigou, Meadows e Tietenberg. Assim, também, indispensável foi inserir na discussão, dados, conceitos e o histórico da região em discussão qual seja, a Amazônia (especialmente a roraimense) bioma possuidor de apelo internacional haja vista sua indiscutível importância para o equilíbrio ambiental do Brasil e sua contribuição para todo o planeta terra. Por fim, conjugou-se a aplicação da ACB e suas ferramentas (como os método de valoração ambiental) com o manejo florestal sustentável (MFS) objetivando o alcance do desiderato inicial, qual seja, a viabilidade ou não de modelos de extração de madeira na Amazônia de Roraima. O resultado obtido foi de que, dos três modelos estudados apenas o modelo em manejo florestal sustentável (MFS) apresentou viabilidade econômica e ambiental, tendo em vista que nos dois primeiros modelos em sistema e produção convencional (um sem e outro com custo ambiental) não atenderam aos requisitos dos indicadores do estudo: valor presente líquido (VPL), taxa interna de retorno (TIR) e a razão B/C. Aliás, duas das análises que levaram em conta os custos dos impactos ambientais foram denominadas de análise custo-benefício ampliada ou ambiental (ACBA), que são variações ou alternativas ao modelo de ACB convencional ou simples. Desse modo, o benefício do modelo MFS supera seus custos o que torna atrativos para investidores privados e públicos, bem como para financiamento via fundos ambientais nacionais e internacionais ou via financiamento via Banco Mundial, Comunidade Européia, entre outros agentes de fomento. / This study approach the cost-benefit analysis (CBA) in sustainable forest management (SFM) in Roraima, Brazilian State owned by Amazon that just as other states suffer from a lack of economic alternatives facing the regional and international pressure not to use of forest resources. Therefore, this study sought to investigate the feasibility of the activity of sustainable forest management (SFM) in order to support future developments that are both economically viable and environmentally sound. To achieve this it was necessary to thoroughly expose the chain of sustainable development, such as its origin, historical context, its concepts, treaties and conventions which ensure legal thinking conservationist. Moreover, it was necessary grounding in economic science, with the content on the transverse Kuznets Curve, a concept of public goods and the implications of externalities in the environmental cost, as well as contributions from economists like Pigou, Meadows and Tietenberg. So, too, was essential to enter into the discussion, data, concepts and history of the region under discussion which is the Amazon (especially roraimense) biome possessed of international appeal has seen its unquestionable importance to the environmental balance of Brazil and its contribution to all the planet earth. Finally, conjugated to the implementation of the CBA and its tools (such as the valuation method) with sustainable forest management (SFM) in order to reach the first desideratum, namely, the feasibility or otherwise of models of logging on Amazon Roraima. The result was that the three models studied only the model in sustainable forest management (SFM) presented economic and environmental viability, given that the first two models and conventional production system (one without and one with environmental cost) is not met the requirements of the study indicators: net present value (NPV), internal rate of return (IRR) and the ratio B/C. Indeed, two of the analysis that took into account the costs of environmental impacts were identified as extended cost-benefit analysis or environmental (ACBA), which are a variation, or alternatives to the conventional model of CBA or simple. Thus, the benefit of the MFS model exceeds its cost which makes it attractive for private and public investors, as well as financing through national and international environmental funds or by funding through the World Bank, European Community, and other agents of promotion.
34

Análise custo-benefício do manejo florestal sustentável em Roraima

Paiva, Natalino Araújo January 2011 (has links)
Esta dissertação aborda a análise custo-benefício (ACB) em manejo florestal sustentável (MFS) em Roraima, Unidade da Federação pertencente à Amazônia Legal que assim como os outros Estados sofrem com a falta de alternativas econômicas frente à pressão regional e internacional de não uso dos recursos da floresta. Por essa razão, este trabalho, procurou estudar a viabilidade da atividade de manejo florestal sustentável (MFS), a fim de subsidiar futuros empreendimentos que sejam ao mesmo tempo economicamente viável e ambientalmente corretos. Para alcançar tal objetivo foi necessário expor exaustivamente a corrente do desenvolvimento sustentável, tais como, sua origem, o contexto histórico, seus conceitos, tratados e convenções que asseguraram juridicamente o pensamento conservacionista. Além disso, foi preciso embasamento na Ciência Econômica, com o conteúdo transversal sobre a Curva de Kuznets, conceito de bens públicos e as implicâncias das externalidades no custo ambiental, bem como de contribuições de economistas como Pigou, Meadows e Tietenberg. Assim, também, indispensável foi inserir na discussão, dados, conceitos e o histórico da região em discussão qual seja, a Amazônia (especialmente a roraimense) bioma possuidor de apelo internacional haja vista sua indiscutível importância para o equilíbrio ambiental do Brasil e sua contribuição para todo o planeta terra. Por fim, conjugou-se a aplicação da ACB e suas ferramentas (como os método de valoração ambiental) com o manejo florestal sustentável (MFS) objetivando o alcance do desiderato inicial, qual seja, a viabilidade ou não de modelos de extração de madeira na Amazônia de Roraima. O resultado obtido foi de que, dos três modelos estudados apenas o modelo em manejo florestal sustentável (MFS) apresentou viabilidade econômica e ambiental, tendo em vista que nos dois primeiros modelos em sistema e produção convencional (um sem e outro com custo ambiental) não atenderam aos requisitos dos indicadores do estudo: valor presente líquido (VPL), taxa interna de retorno (TIR) e a razão B/C. Aliás, duas das análises que levaram em conta os custos dos impactos ambientais foram denominadas de análise custo-benefício ampliada ou ambiental (ACBA), que são variações ou alternativas ao modelo de ACB convencional ou simples. Desse modo, o benefício do modelo MFS supera seus custos o que torna atrativos para investidores privados e públicos, bem como para financiamento via fundos ambientais nacionais e internacionais ou via financiamento via Banco Mundial, Comunidade Européia, entre outros agentes de fomento. / This study approach the cost-benefit analysis (CBA) in sustainable forest management (SFM) in Roraima, Brazilian State owned by Amazon that just as other states suffer from a lack of economic alternatives facing the regional and international pressure not to use of forest resources. Therefore, this study sought to investigate the feasibility of the activity of sustainable forest management (SFM) in order to support future developments that are both economically viable and environmentally sound. To achieve this it was necessary to thoroughly expose the chain of sustainable development, such as its origin, historical context, its concepts, treaties and conventions which ensure legal thinking conservationist. Moreover, it was necessary grounding in economic science, with the content on the transverse Kuznets Curve, a concept of public goods and the implications of externalities in the environmental cost, as well as contributions from economists like Pigou, Meadows and Tietenberg. So, too, was essential to enter into the discussion, data, concepts and history of the region under discussion which is the Amazon (especially roraimense) biome possessed of international appeal has seen its unquestionable importance to the environmental balance of Brazil and its contribution to all the planet earth. Finally, conjugated to the implementation of the CBA and its tools (such as the valuation method) with sustainable forest management (SFM) in order to reach the first desideratum, namely, the feasibility or otherwise of models of logging on Amazon Roraima. The result was that the three models studied only the model in sustainable forest management (SFM) presented economic and environmental viability, given that the first two models and conventional production system (one without and one with environmental cost) is not met the requirements of the study indicators: net present value (NPV), internal rate of return (IRR) and the ratio B/C. Indeed, two of the analysis that took into account the costs of environmental impacts were identified as extended cost-benefit analysis or environmental (ACBA), which are a variation, or alternatives to the conventional model of CBA or simple. Thus, the benefit of the MFS model exceeds its cost which makes it attractive for private and public investors, as well as financing through national and international environmental funds or by funding through the World Bank, European Community, and other agents of promotion.
35

Análise custo-benefício do manejo florestal sustentável em Roraima

Paiva, Natalino Araújo January 2011 (has links)
Esta dissertação aborda a análise custo-benefício (ACB) em manejo florestal sustentável (MFS) em Roraima, Unidade da Federação pertencente à Amazônia Legal que assim como os outros Estados sofrem com a falta de alternativas econômicas frente à pressão regional e internacional de não uso dos recursos da floresta. Por essa razão, este trabalho, procurou estudar a viabilidade da atividade de manejo florestal sustentável (MFS), a fim de subsidiar futuros empreendimentos que sejam ao mesmo tempo economicamente viável e ambientalmente corretos. Para alcançar tal objetivo foi necessário expor exaustivamente a corrente do desenvolvimento sustentável, tais como, sua origem, o contexto histórico, seus conceitos, tratados e convenções que asseguraram juridicamente o pensamento conservacionista. Além disso, foi preciso embasamento na Ciência Econômica, com o conteúdo transversal sobre a Curva de Kuznets, conceito de bens públicos e as implicâncias das externalidades no custo ambiental, bem como de contribuições de economistas como Pigou, Meadows e Tietenberg. Assim, também, indispensável foi inserir na discussão, dados, conceitos e o histórico da região em discussão qual seja, a Amazônia (especialmente a roraimense) bioma possuidor de apelo internacional haja vista sua indiscutível importância para o equilíbrio ambiental do Brasil e sua contribuição para todo o planeta terra. Por fim, conjugou-se a aplicação da ACB e suas ferramentas (como os método de valoração ambiental) com o manejo florestal sustentável (MFS) objetivando o alcance do desiderato inicial, qual seja, a viabilidade ou não de modelos de extração de madeira na Amazônia de Roraima. O resultado obtido foi de que, dos três modelos estudados apenas o modelo em manejo florestal sustentável (MFS) apresentou viabilidade econômica e ambiental, tendo em vista que nos dois primeiros modelos em sistema e produção convencional (um sem e outro com custo ambiental) não atenderam aos requisitos dos indicadores do estudo: valor presente líquido (VPL), taxa interna de retorno (TIR) e a razão B/C. Aliás, duas das análises que levaram em conta os custos dos impactos ambientais foram denominadas de análise custo-benefício ampliada ou ambiental (ACBA), que são variações ou alternativas ao modelo de ACB convencional ou simples. Desse modo, o benefício do modelo MFS supera seus custos o que torna atrativos para investidores privados e públicos, bem como para financiamento via fundos ambientais nacionais e internacionais ou via financiamento via Banco Mundial, Comunidade Européia, entre outros agentes de fomento. / This study approach the cost-benefit analysis (CBA) in sustainable forest management (SFM) in Roraima, Brazilian State owned by Amazon that just as other states suffer from a lack of economic alternatives facing the regional and international pressure not to use of forest resources. Therefore, this study sought to investigate the feasibility of the activity of sustainable forest management (SFM) in order to support future developments that are both economically viable and environmentally sound. To achieve this it was necessary to thoroughly expose the chain of sustainable development, such as its origin, historical context, its concepts, treaties and conventions which ensure legal thinking conservationist. Moreover, it was necessary grounding in economic science, with the content on the transverse Kuznets Curve, a concept of public goods and the implications of externalities in the environmental cost, as well as contributions from economists like Pigou, Meadows and Tietenberg. So, too, was essential to enter into the discussion, data, concepts and history of the region under discussion which is the Amazon (especially roraimense) biome possessed of international appeal has seen its unquestionable importance to the environmental balance of Brazil and its contribution to all the planet earth. Finally, conjugated to the implementation of the CBA and its tools (such as the valuation method) with sustainable forest management (SFM) in order to reach the first desideratum, namely, the feasibility or otherwise of models of logging on Amazon Roraima. The result was that the three models studied only the model in sustainable forest management (SFM) presented economic and environmental viability, given that the first two models and conventional production system (one without and one with environmental cost) is not met the requirements of the study indicators: net present value (NPV), internal rate of return (IRR) and the ratio B/C. Indeed, two of the analysis that took into account the costs of environmental impacts were identified as extended cost-benefit analysis or environmental (ACBA), which are a variation, or alternatives to the conventional model of CBA or simple. Thus, the benefit of the MFS model exceeds its cost which makes it attractive for private and public investors, as well as financing through national and international environmental funds or by funding through the World Bank, European Community, and other agents of promotion.
36

The Integration of Iterative Convergent Photogrammetric Models and UAV View and Path Planning Algorithms into the Aerial Inspection Practices in Areas with Aerial Hazards

Freeman, Michael James 01 December 2020 (has links)
Small unmanned aerial vehicles (sUAV) can produce valuable data for inspections, topography, mapping, and 3D modeling of structures. Used by multiple industries, sUAV can help inspect and study geographic and structural sites. Typically, the sUAV and camera specifications require optimal conditions with known geography and fly pre-determined flight paths. However, if the environment changes, new undetectable aerial hazards may intersect new flight paths. This makes it difficult to construct autonomous flight path missions that are safe in post-hazard areas where the flight paths are based on previously built models or previously known terrain details. The goal of this research is to make it possible for an unskilled pilot to obtain high quality images at key angles which will facilitate the inspections of dangerous environments affected by natural disasters through the construction of accurate 3D models. An iterative process with converging variables can circumvent the current deficit in flying UAVs autonomously and make it possible for an unskilled pilot to gather high quality data for the construction of photogrammetric models. This can be achieved by gaining preliminary photogrammetric data, then creating new flight paths which consider new developments contained in the generated dense clouds. Initial flight paths are used to develop a coarse representation of the target area by aligning key tie points of the initial set of images. With each iteration, a 3D mesh is used to compute a new optimized view and flight path used for the data collection of a better-known location. These data are collected, the model updated, and a new flight path is computed until the model resolution meets the required heights or ground sample distances (GSD). This research uses basic UAVs and camera sensors to lower costs and reduce the need for specialized sensors or data analysis. The four basic stages followed in the study include: determination of required height reductions for comparison and convergent limitation, construction of real-time reconnaissance models, optimized view and flight paths with vertical and horizontal buffers constructed from previous models, and develop an autonomous process that combines the previous stages iteratively. This study advances the use of autonomous sUAV inspections by developing an iterative process of flying a sUAV to potentially detect and avoid buildings, trees, wires, and other hazards in an iterative manner with minimal pilot experience or human intervention; while optimally collecting the required images to generate geometric models of predetermined quality.
37

Forensic Validation of 3D models

Lindberg, Mimmi January 2020 (has links)
3D reconstruction can be used in forensic science to reconstruct crime scenes and objects so that measurements and further information can be acquired off-site. It is desirable to use image based reconstruction methods but there is currently no procedure available for determining the uncertainty of such reconstructions. In this thesis the uncertainty of Structure from Motion is investigated. This is done by exploring the literature available on the subject and compiling the relevant information in a literary summary. Also, Monte Carlo simulations are conducted to study how the feature position uncertainty affects the uncertainty of the parameters estimated by bundle adjustment. The experimental results show that poses of cameras that contain few image correspondences are estimated with higher uncertainty. The poses of such cameras are estimated with lesser uncertainty if they have feature correspondences in cameras that contain a higher number of projections.
38

Evaluation of Unmanned Aerial Vehicle Flight Parameters That Impact Stockpile Volume Computations

Hastings, Nicole Marie 08 December 2023 (has links) (PDF)
Stockpile volumes are monitored by their companies as the product (i.e., aggregate, soil) is moved in and out of the facilities to ensure minimal product loss. Companies are mandated to report product movement to the government to ensure that the aggregate and soil is going where it is supposed to go. Many tools are used to monitor stockpile volumes including truck scales (to weigh incoming and outgoing trucks), light detection and ranging (LiDAR), Global Navigation Satellite System (GNSS) equipment, and unmanned aerial vehicle (UAV) photogrammetry. These processes give a good estimate of stockpile volumes. Errors in these estimates typically come from transportation and natural degradation of the stockpile. Not much research has been done on the best practices when using UAV photogrammetry to find the volume of a stockpile. Most recent research is about specific situations for finding a stockpile volume and whether UAV photogrammetry is as good as traditional methods for finding stockpile's volume. This study focuses on the effect of the flight height, camera angle, and presence of ground control points (GCP) in processing on the final volume calculated. Six UAV flights were done for this study; three different flight heights and two different camera angles. Additionally, the UAV reconstructed models were run with and without the GCPs to give twelve reconstructed volumes to examine for statistically significant differences. A similar study was done by Tucci et. al\cite{Tucci2019} where they focused on only camera orientation and found that the camera orientation was not statistically significant. We found that the differences between if GCPs in processing or not and between each flight elevation was statistically insignificant. We found that the differences in camera orientation between nadir and oblique were statistically significant. These different results could be due to many variables including differences in the dataset, differences in the statistical analysis, or the difference in stockpile size. We recommend using a high flight elevation and oblique photos to develop an efficient, accurate model.
39

Dissertation_Meghdad_revised_2.pdf

Seyyed Meghdad Hasheminasab (14030547) 30 November 2022 (has links)
<p> </p> <p>Modern remote sensing platforms such as unmanned aerial vehicles (UAVs) that can carry a variety of sensors including RGB frame cameras, hyperspectral (HS) line cameras, and LiDAR sensors are commonly used in several application domains. In order to derive accurate products such as point clouds and orthophotos, sensors’ interior and exterior orientation parameters (IOP and EOP) must be established. These parameters are derived/refined in a triangulation framework through minimizing the discrepancy between conjugate features extracted from involved datasets. Existing triangulation approaches are not general enough to deal with varying nature of data from different sensors/platforms acquired in diverse environmental conditions. This research develops a generic triangulation framework that can handle different types of primitives (e.g., point, linear, and/or planar features), and sensing modalities (e.g., RGB cameras, HS cameras, and/or LiDAR sensors) for delivering accurate products under challenging conditions with a primary focus on digital agriculture and stockpile monitoring application domains. </p>
40

Remote Sensing and UAVs for the Geomorphological and Habitat Analysis in Ephemeral and Permanent Mediterranean Streams

Puig Mengual, Carlos Antonio 29 November 2021 (has links)
Tesis por compendio / [ES] Los ecosistemas riparios presentan una gran variabilidad, desde un punto de vista geomorfológico como hidrológico y ecológico, incluyendo las complejas interacciones que la morfología y la vegetación de ribera puede presentar. La vegetación se presenta como un factor físico muy influyente en los sistemas fluviales, con una relación directa en los procesos geomorfológicos que tienen lugar en los corredores fluviales. La detección, monitoreo y evaluación de los procesos que se desarrollan en el espacio ripario son clave a la hora de poder entender las funciones ecológicas y el desarrollo de dichos hábitats, y por tanto para tomar decisiones para su conservación y restauración. Según la distribución de especies y los rasgos de las plantas, las comunidades vegetales y su dinámica presentan distintas características en el ecosistema ripario, a las cuales los métodos de detección y monitoreo deben adaptarse. Los constantes cambios que sufren estos espacios a lo largo del tiempo se deben en gran parte a procesos físicos relacionados con las dinámicas de erosión y sedimentación, las variaciones de la trayectoria del cauce, variaciones en la distribución de especies y vegetación en el bosque de ribera, etc., pero también se deben al impacto antropogénico, que puede llegar a generar grandes desajustes en la dinámica ecológica de los ecosistemas en cuestión. Debido a las interacciones de diversos procesos y alteraciones antropogénicas, y las complejas dinámicas espacio-temporales, resulta necesario continuar desarrollando metodologías teóricas y prácticas para la monitorización y caracterización de estos ecosistemas. La teledetección, incluyendo el uso de drones, se presenta como una herramienta muy interesante y óptima para el mapeo y recogida de información en estos espacios naturales. Los beneficios que demuestran las aeronaves no tripuladas -UAV- incluyen las mejoras en la resolución espacial y temporal de los datos capturados, así como la cartografía de áreas extensas en poco tiempo, lo que los convierte en instrumentos clave en tareas de gestión y conservación de los espacios riparios. La necesidad de estudiar la dinámica geomorfológica que se produce en los cauces fluviales ha sido la principal motivación en los estudios que se presentan en esta tesis doctoral. Los capítulos 2 y 3 se basan en técnicas de captura de datos con láser escáner terrestre (TLS) y en el modelado de los datos obtenidos en vuelos fotogramétricos de UAV. Con ellos se han caracterizado los procesos que tienen lugar en una cierta área de estudio, un cauce efímero del sureste de la Península Ibérica, la Rambla de la Azohía (Murcia). Estos estudios también han permitido comparar el ajuste y precisión de los datos capturados a partir de dos técnicas distintas. Además, el interés en caracterizar los cauces fluviales con un flujo permanente ha motivado el estudio de la topografía sumergida en un tramo de río, segmentado por tipos de mesohábitat. Así pues, el capítulo 4 presenta un algoritmo y una herramienta de corrección para el efecto de la refracción en un tramo del rio Palancia (Castellón), para llevar a cabo la correcta representación de la morfología del lecho sumergido. A partir de la metodología planteada y el algoritmo desarrollado, es posible minimizar los efectos de distorsión debidos a la presencia del agua, para obtener la reconstrucción tridimensional del lecho a partir de imágenes tomadas con UAV. La construcción del modelo 3D se llevó a cabo mediante la técnica de Structure from Motion. Finalmente, y como elemento clave en la dinámica de los ecosistemas riparios, el capítulo 5 desarrolla una metodología para clasificar las fases de sucesión de la vegetación del bosque ripario. Dichas fases de sucesión se basan en la metodología del proyecto RIPFLOW, que también está implementada en el modelo dinámico CASiMiR-vegetation. / [CA] Els ecosistemes riparis presenten una gran variabilitat, des d'un punt de vista geomorfològic com a hidrològic i ecològic, incloent les complexes interaccions que la morfologia i la vegetació de ribera pot presentar. La vegetació es presenta com un factor físic molt influent en els sistemes fluvials, amb una relació directa en els processos geomorfològics que tenen lloc en els corredors fluvials. La detecció, monitoratge i avaluació dels processos que es desenvolupen en l'espai ripari són clau a l'hora de poder entendre les funcions ecològiques i el desenvolupament d'aquests hàbitats, i per tant per a prendre decisions per a la seua conservació i restauració. Segons la distribució d'espècies i els trets de les plantes, les comunitats vegetals i la seua dinàmica presenten diferents característiques en l'ecosistema ripario, a les quals els mètodes de detecció i monitoratge han d'adaptar-se. Els constants canvis que pateixen aquests espais al llarg del temps es deuen en gran part a processos físics relacionats amb les dinàmiques d'erosió i sedimentació, les variacions de la trajectòria del llit, variacions en la distribució d'espècies i vegetació en el bosc de ribera, etc., però també es deuen a l'impacte antropogènic, que pot arribar a generar grans desajustaments en la dinàmica ecològica dels ecosistemes en qüestió. A causa de les interaccions de diversos processos i alteracions antropogèniques, i les complexes dinàmiques espaciotemporals, resulta necessari continuar desenvolupant metodologies teòriques i pràctiques per al monitoratge i caracterització d'aquests ecosistemes. La teledetecció, incloent l'ús de drons, es presenta com una eina molt interessant i òptima per al mapatge i recollida d'informació en aquests espais naturals. Els beneficis que demostren les aeronaus no tripulades -UAV- inclouen les millores en la resolució espacial i temporal de les dades capturades, així com la cartografia d'àrees extenses en poc temps, la qual cosa els converteix en instruments clau en tasques de gestió i conservació dels espais riparis. La necessitat d'estudiar la dinàmica geomorfològica que es produeix en els llits fluvials ha sigut la principal motivació en els estudis que es presenten en aquesta tesi doctoral. Els capítols 2 i 3 es basen en tècniques de captura de dades amb làser escàner terrestre (TLS) i en el modelatge de les dades obtingudes en vols fotogramètrics de UAV. Amb ells s'han caracteritzat els processos que tenen lloc en una certa àrea d'estudi, un llit efímer del sud-est de la Península Ibèrica, la Rambla de la Azohía (Múrcia). Aquests estudis també han permés comparar l'ajust i precisió de les dades capturades a partir de dues tècniques diferents. A més, l'interés a caracteritzar els llits fluvials amb un flux permanent ha motivat l'estudi de la topografia submergida en un tram de riu, segmentat per tipus de mesohábitat. Així doncs, el capítol 4 presenta un algorisme i una eina de correcció per a l'efecte de la refracció en un tram del va riure Palància (Castelló), per a dur a terme la correcta representació de la morfologia del llit submergit. A partir de la metodologia plantejada i l'algorisme desenvolupat, és possible minimitzar els efectes de distorsió deguts a la presència de l'aigua, per a obtindre la reconstrucció tridimensional del llit a partir d'imatges preses amb UAV. La construcció del model 3D es va dur a terme mitjançant la tècnica de Structure from Motion. Finalment, i com a element clau en la dinàmica dels ecosistemes riparis, el capítol 5 desenvolupa una metodologia per a classificar les fases de successió de la vegetació del bosc ripari. Aquestes fases de successió es basen en la metodologia del projecte RIPFLOW, que també està implementada en el model dinàmic CASiMiR-vegetation. / [EN] Riparian ecosystems show great variability, from a geomorphological, hydrological and ecological point of view, including the complex interactions that riparian morphology and vegetation can present. Vegetation appears as a very influential physical factor in river systems, with a direct relationship in the geomorphological processes that take place in river corridors. The detection, monitoring and evaluation of the processes that take place in the riparian space are key when it comes to understanding the ecological functions and development of these habitats, and therefore for making decisions for their conservation and restoration. According to the distribution of species and plant traits, plant communities and their dynamics present different characteristics in the riparian ecosystem, to which detection and monitoring methods must be adapted. The constant changes that these spaces undergo over time are largely due to physical processes related to the dynamics of erosion and sedimentation, variations in the path of the channel, variations in the distribution of species and vegetation in the riparian forest, etc. These processes also are due to the anthropogenic impact, which can generate major imbalances in the ecological dynamics of the ecosystems in question. Due to the interactions of various anthropogenic processes and alterations, and the complex spatio-temporal dynamics, it is necessary to continue developing theoretical and practical methodologies for the monitoring and characterization of these ecosystems. Remote sensing, including the use of drones, is presented as a very interesting and optimal tool for mapping and collecting information in these natural spaces. The benefits demonstrated by unmanned aircraft -UAV- include improvements in the spatial and temporal resolution of the captured data, as well as the mapping of large areas in a short time, which makes them key instruments in the management and conservation tasks of riparian spaces. The need to study the geomorphological dynamics that occur in river channels has been the main motivation in the studies presented in this doctoral thesis. Chapters 2 and 3 are based on ground-based laser scanner (TLS) data capture techniques and modelling of UAV photogrammetric flight data. They have characterized the processes that take place in a certain study area, an ephemeral riverbed in the southeast of the Iberian Peninsula, the Rambla de la Azohía (Murcia). These studies have also made it possible to compare the fit and precision of the data captured from two different techniques. In addition, the interest in characterizing the fluvial channels with a permanent flow has motivated the study of the submerged topography in a stretch of river, segmented by types of mesohabitat. Thus, chapter 4 presents an algorithm and a correction tool for the effect of refraction in a stretch of the Palancia river (Castellón), to carry out the correct representation of the submerged bed morphology. From the proposed methodology and the developed algorithm, it is possible to minimize the distortion effects due to the presence of water, to obtain the three-dimensional reconstruction of the bed from images taken with UAVs. The construction of the 3D model was carried out using the Structure from Motion technique. Finally, and as a key element in the dynamics of riparian ecosystems, chapter 5 develops a methodology to classify the phases of succession of riparian forest vegetation. These succession phases are based on the RIPFLOW project methodology, which is also implemented in the dynamic CASiMiR-vegetation model. / Agradezco a Francisca Segura y a Carles Sanchis por su ayuda y trabajo conjunto en el proyecto “Natural and anthropogenic changes in Mediterranean river drainage basins: historical impacts on rivers morphology, sedimentary flows and vegetation” financiado por el Ministerio de Economía y Competitividad (MINECO) (CGL2013-44917-R). Agradezco también a la Universidad de Murcia y la Universidad de Alicante así como al proyecto de investigación “Respuesta morfológica y sistémica al cambio climático en cauces efímeros mediterráneos: dinámica, resiliencia y propuestas de actuación” funded by ERDF/Spanish Ministry of Science, Innovation and Universities—State Research Agency/Project CGL2017-84625-C2-1-R (CCAMICEM); State Program for Research, Development and Innovation Focused on the Challenges of Society, del Ministerio de Economía y Competitividad (MINECO) y EU FEDER (Project TEC2017- 85244-C2-1-P) y de la Universidad de Alicante (vigrob-157 and GRE18-05). / Puig Mengual, CA. (2021). Remote Sensing and UAVs for the Geomorphological and Habitat Analysis in Ephemeral and Permanent Mediterranean Streams [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/177643 / Compendio

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