Part I: Various image reconstruction algorithms used for subsurface targets are reviewed. It is shown how some approximate wavefield inversion techniques: Stripmap Synthetic Aperture Radar (SAR), Kirchhoff Migration (KM) and Frequency-Wavenumber (FK) migration are developed from various models for wavefield scattering. The similarities of these techniques are delineated both from a theoretical and practical perspective and it is shown that Stripmap SAR is, computationally, almost identical to FK migration. A plane wave interpretation of both Stripmap SAR and FK migration is used to show why they are so similar. The electromagnetic assumptions made in the image reconstruction algorithms are highlighted. In addition, it is shown that, theoretically, FK and KM are identical. Image reconstruction results for KM, Stripmap SAR and FK are shown for both synthetic and experimental Ground Penetrating Radar (GPR) data. Subjectively the reconstructed images show little difference, but computationally, Stripmap SAR (and therefore, FK migration) are much more efficient. Part II: A preliminary investigation into the use of the Singularity Expansion Method (SEM) for use in identifying landmines is completed using a Finite-Difference Time-Domain code to simulate a simplified GPR system. The Total Least Squares Matrix Pencil Method (TLS-MPM) is used to determine the complex poles from an arbitrary late-time signal. Both dielectric and metallic targets buried in lossless and lossy half-spaces are considered. Complex poles (resonances) of targets change significantly when the objects are buried in an external medium, and perturbation formulae for Perfect Electric Conductor (PEC) and dielectric targets are highlighted and used. These perturbation formulae are developed for homogenous surrounding media, and their utilization for the half-space (layered medium) GPR problem causes inaccuracies in their predictions. The results show that the decay rate (real part) of the complex poles is not suitable for identification in this problem, but that with further research, the resonant frequency (imaginary part) of the complex poles shows promise as an identification feature.

This study aims to evaluate the ability of high-frequency (450 and 900 MHz) ground-penetrating radar (GPR) to monitor the effects of an ethanol release over an existing gasoline-contaminated zone. In September 2009, 184L of denatured ethanol mixture (E95) was released into an unconfined sand aquifer directly over gasoline residuals (E10) released the previous year. GPR profiling prior to the ethanol release indicated that the residual gasoline-contaminated zone was largely confined to its initial release point. The GPR profiling performed post ethanol release observed strong shallow reflection events which propagated laterally away from the trench over a one-month period, at which point the maximum extent was established. The effects of the ethanol were also observed with the 450MHz frequency, in the form of an apparent “velocity pull-up” of a stratigraphic reflector. After the initial expansion, reduction in reflection amplitude and increasing traveltimes within the trench, were observed until the onset of winter conditions and the development of frozen soil. Over the winter the presence of ethanol inhibited the freezing process of the pore water in the contaminated zone, thus resulting in a difference in the dielectric properties of the unfrozen verse frozen zone. The unfrozen zone was significantly greater than the spatial extent of the strong reflection events that were monitored through GPR prior to winter. The spatial extent and depth of the unfrozen zone imaged by the GPR profiling was confirmed by a physical impedance depth survey. After thaw, evidence of the ethanol or gasoline was absent until mid-summer, when the water table dropped to approximately 80cm. At this point strong reflection events were again observed throughout the contaminated zone.

Part I: Various image reconstruction algorithms used for subsurface targets are reviewed. It is shown how some approximate wavefield inversion techniques: Stripmap Synthetic Aperture Radar (SAR), Kirchhoff Migration (KM) and Frequency-Wavenumber (FK) migration are developed from various models for wavefield scattering. The similarities of these techniques are delineated both from a theoretical and practical perspective and it is shown that Stripmap SAR is, computationally, almost identical to FK migration. A plane wave interpretation of both Stripmap SAR and FK migration is used to show why they are so similar. The electromagnetic assumptions made in the image reconstruction algorithms are highlighted. In addition, it is shown that, theoretically, FK and KM are identical. Image reconstruction results for KM, Stripmap SAR and FK are shown for both synthetic and experimental Ground Penetrating Radar (GPR) data. Subjectively the reconstructed images show little difference, but computationally, Stripmap SAR (and therefore, FK migration) are much more efficient. Part II: A preliminary investigation into the use of the Singularity Expansion Method (SEM) for use in identifying landmines is completed using a Finite-Difference Time-Domain code to simulate a simplified GPR system. The Total Least Squares Matrix Pencil Method (TLS-MPM) is used to determine the complex poles from an arbitrary late-time signal. Both dielectric and metallic targets buried in lossless and lossy half-spaces are considered. Complex poles (resonances) of targets change significantly when the objects are buried in an external medium, and perturbation formulae for Perfect Electric Conductor (PEC) and dielectric targets are highlighted and used. These perturbation formulae are developed for homogenous surrounding media, and their utilization for the half-space (layered medium) GPR problem causes inaccuracies in their predictions. The results show that the decay rate (real part) of the complex poles is not suitable for identification in this problem, but that with further research, the resonant frequency (imaginary part) of the complex poles shows promise as an identification feature.

The study of mechanical energy and electrical energy dissipation in cementitious materials can lead to development of high damping concrete for structural applications, and new non-destructive testing techniques for use on existing concrete structures. This research aims to improve mechanical damping properties of cementitious materials and determine durability parameters from complex permittivity measurements. Damping was improved by utilizing poromechanical effects, and by adding viscoelastic and nanometric inclusions. Poromechanics was utilized to model and predict damping on specimens designed to maximize poromechanical effects, and composite theory was used to predict composite bounds for the loss tangent, i.e. modeling the effects on damping due to the addition of viscoelastic inclusions. Experimental results indicated that substantial damping improvement can be realized by both poromechanical effects and adding novel inclusions into cement pastes. The models were able to predict experimentally measured damping as a function of loading frequency. The electrical energy dissipation in cementitious materials was studied by dielectric spectroscopy as a function of moisture state and pore structure/permeability. The results were compared to predictions from multiphase composite modeling, where the properties of the confined water was inversely determined and used to predict moisture content. It was found that moisture state of cementitious materials has a linear relation to the complex permittivity over a wide variety of frequency ranges. Composite model prediction indicated that permeability of saturated cementitious materials studied in this research is likely dependent on the amount of free water in the pores. Permeability can be inferred from the pore structure of the cement paste via complex permittivity measurements by conditioning cement paste at different levels of relative humidity.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2018-03-12T14:54:58Z No. of bitstreams: 1 RebecaSeabraDeLima_DISSERT.pdf: 11296655 bytes, checksum: dbc6cc1712a785c167ec0c4025633643 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-03-14T20:56:43Z (GMT) No. of bitstreams: 1 RebecaSeabraDeLima_DISSERT.pdf: 11296655 bytes, checksum: dbc6cc1712a785c167ec0c4025633643 (MD5) / Made available in DSpace on 2018-03-14T20:56:43Z (GMT). No. of bitstreams: 1 RebecaSeabraDeLima_DISSERT.pdf: 11296655 bytes, checksum: dbc6cc1712a785c167ec0c4025633643 (MD5) Previous issue date: 2017-08-07 / O trabalho envolve o imageamento e modelagem digital de uma col?nia microbial?tica neoproterozoica do afloramento da Fazenda Arrecife (BA), com o uso do m?todo Ground Penetrating Radar (GPR) e a aplica??o de atributos matem?ticos. Concomitantemente, foi realizado o levantamento de se??es colunares e a aquisi??o de perfis radioativos, permitindo a caracteriza??o das f?cies sedimentares. Foram tamb?m realizados estudos petrogr?ficos e an?lises qu?micas (MEV/SED e FRX) para identificar a composi??o dos n?veis escuros (estilol?ticos), que geram reflex?es nos radargramas. O atributo ?Amplitude Instant?nea? real?ou a col?nia de microbialitos (baixa amplitude), pois exibe um padr?o de assinatura GPR distinto. O atributo de ?Energia? apresentou resultados semelhantes ao de ?Amplitude Instant?nea?, proporcionando uma melhor visualiza??o da lamina??o interna do microbialito colunar. J? o atributo de ?Similaridade? real?ou o limite da col?nia com os dep?sitos tempest?ticos. A combina??o ?Tra?o de Hilbert com Energia? mostrou um realce mais significativo do limite de crescimento da col?nia microbial?tica do que o atributo de ?Energia? isolado. J? o atributo ?Tra?o de Hilbert com Similaridade? real?ou a estrutura interna da col?nia microbial?tica. Foram descritas as f?cies microbial?ticas (MCme, MCm e MCma) e f?cies tempest?tica (Cahm). O estudo petrogr?fico indicou a presen?a de minerais como limonita e/ou siderita, o que corrobora com os resultados das an?lises qu?micas. As an?lises qu?micas com MEV/SED e FRX mostram que no n?vel estilol?tico ocorre maiores valores de Fe (11,9%), justificando assim os fortes refletores observados nas se??es GPR, que s?o resultado do contraste eletromagn?tico entre o meio (?calc?rio = 6,55) e o os n?veis estilol?ticos (?ferro= 14,2). Para a modelagem digital, foi elaborado um s?lido 3D que representa adequadamente a col?nia microbial?tica. A metodologia abordada neste trabalho, envolvendo a aplica??o de atributos aos dados GPR, permitiu real?ar caracter?sticas do microbialito que foram pouco observadas no dado original. Portanto, pode ser utilizada em outros contextos geol?gicos semelhantes (aflorantes ou n?o-aflorantes). / This thesis involves the digital imaging and modeling of a neoproterozoic microbialitic colony in the Fazenda Arrecife (BA) outcrop, using the Ground Penetrating Radar (GPR) method and the application of mathematical attributes. Concomitantly, columnar sections and radioactive profiles acquisition were carried out, allowing the characterization of the sedimentary facies. Petrographic studies and chemical analysis (SEM/EDS and XRF) were used to identify the composition of the stylolithic levels that generate reflections in the GPR sections. The "Instantaneous Amplitude" attribute highlighted a microbialite community (low amplitude), which displays different signature pattern. The "Energy" attribute showed a similar result comparing to the "Instantaneous Amplitude". Nevertheless, this attribute provided a better visualization of the internal lamination of the columnar microbialite. The "Similarity" attribute emphasized the community boundary. The "Hilbert Trace/Energy" combination showed significant enhancement of the microbial growth boundaries compared to the "Energy" attribute. The attribute "Hilbert Trace/Similarity" highlighted the internal structure of the microbial community. The described facies were designated as microbialitic facies (MCme, MCm and MCma) and tempestite facies (Cahm). Minerals, such as limonite and/or siderite, were identified by the petrographic study, which corroborates with the chemical analysis results. The chemical analysis shows high Fe values to the stylolithic level, which causes the reflections observed in the GPR sections, due to the electromagnetic contrast between the microbialite (? = 6.55) and the stylolithic levels (? = 14.2). The generated 3D solid properly represents a microbial community. The attribute application to GPR data allowed to highlight the microbialitic features not observed in the original data. Therefore, this application can be used in similar geologic contexts.

Magíster en Ciencias, Mención Geofísica / El Método RES es un método geofísico similar al método sísmico, pero que en lugar de ondas elásticas, se basa en la propagación de ondas electromagnéticas a través de antenas entre un emisor y un receptor, ambos normalmente en la superficie. Para el caso de un glaciar estas ondas se propagan a través del material, interactuando con reflectores internos del hielo y con la interfaz hielo-roca al fondo del glaciar. El espesor de hielo de un glaciar puede ser calculado utilizando este método en base al tiempo de recorrido y una velocidad de propagación de la onda en el medio. Se dispone de datos RES en formato crudo obtenido mediante un sistema de radar aéreo, con el cual se midieron 18 glaciares de la cordillera norte, centro y sur de Chile solicitados por la Dirección General de Aguas (DGA). En base a estos datos se realizó el procesamiento de datos para cada uno de los glaciares y así se obtuvieron espesores de hielo en ciertas transectas medidas sobre el glaciar. En base a estos resultados se realizó una interpolación del espesor para toda el área del glaciar con límites definidos mediante imágenes aéreas y satelitales. Así se calculó un volumen para cada uno de los 18 glaciares. Diversos autores han propuesto fórmulas que relacionan el volumen o espesor medio del hielo en un glaciar con el área de la superficie del mismo. Esto busca dar una respuesta general para una zona determinada en la cual no se pueden realizar mediciones RES, debido a que corresponde a una técnica laboriosa y solo aplicable a glaciares individuales. Es aquí donde surge la necesidad de realizar un ajuste que sea aplicable a los glaciares de la cordillera andina de Chile. Se obtuvo, luego de un minucioso análisis utilizando las áreas y volúmenes obtenidos para el conjunto de datos disponibles, una relación del tipo de Ley de Potencias ($V=C\cdot S^\gamma$) que entrega un resultado válido para ser aplicable sobre glaciares chilenos. La relación área-volumen para glaciares chilenos obtenida en el presente trabajo, fue aplicada sobre los glaciares con áreas entre $0.01$ y $30\ km^2$ del inventario de glaciares a nivel nacional disponible, realizado por la Unidad de Glaciología y Nieves de la DGA. Se calculó una disminución de volumen de $31\%$ respecto a los cálculos realizados aplicando otras relaciones. Debido a los tamaños de los glaciares, la fórmula propuesta puede ser aplicada sobre todos los glaciares entre las regiones XV y X, mientras que puede ser aplicada en forma parcial entre las regiones XI y XII.

Předmětem této práce je polohově orientovaná analýza v kontextu optimalizace mobilních sítí. Popisuje nástroj pro odhadování základních parametrů sítě na místech s neznámými parametry sítě na základě databáze RTR NetTest. Je zde stručně představena oblast velkých dat, strojového učení a shrnutí o konceptu a funkcionalitě aplikace NetTest. Práce ukazuje a porovnává skupinu regresních metod na základě jejich komplexnosti a vhodnosti pro vytvoření map odhadovaných parametrů sítě. Po jejich důkladné 1D analýze je IDW a GPR analyzováno ve 2D a využito pro vytvoření skupiny map odhadu parametrů sítě. Je posouzena i jejich přesnost na základě referenčního měření aplikací NetTest.

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This thesis presents the research and development behind the integration of an autonomous propulsion system for a four-wheeled Ground Penetrating Radar (GPR) measurement unit, previously requiring manual operation. In order to ease the administration of the complex new system, Robot Operating System (ROS) 2 was used as middleware, where an implementation of Light Detection And Ranging (LiDAR) 3D-SLAM (Simultaneous Localization And Mapping) served to secure precise localization of the Unmanned Ground Vehicle (UGV) and mapping of its environment. This, with the ultimate goal of enabling accurate survey execution along paths optimized for various dynamic indoor- and outdoor environments. From a more general point of view, this work can also act as a hardware- and software selection guide for similar projects, especially if stricter physical limitations apply and the autonomous system is not considered the primary system, but the majority of the internal enclosed space of the UGV is reserved for higher purpose equipment or storage requirements. In this first prototype iteration, the mapping accuracy of the autonomous system reached centimeter precision and the execution of surveys in grid- and spiral patterns yielded position accuracies of 5(2) cm and 6(4) cm, respectively. These results are indeed very promising and show the proof of concept needed to enter the next development phase.

To map the subsurface Ground Penetrating Radar (GPR) can be used in a non-invasive way. It is currently done manually by pushing a wheeled device on a handlebar. This thesis suggests an alternative method using an integrated autonomous solution. To ac- complice that: several sensors were fused to give the robot perception of the world, the ability to localize itself within it, and plan a path to reach the goal. Detecting algorithms were implemented and tested to ensure the robot could handle a dynamic and compli- cated world. The results showed that the robot could independently navigate in a grid pattern conducting GPR surveys while avoiding obstacles and finding a safe route. All this will allow for collecting GPR data with precise localization measurements and in paths more detailed than a human operator could. In addition, it enables the operator to be at a safe distance in dangerous environments and to search large areas.