Thesis (Ph. D.)--University of California, Riverside, 2009. / Includes abstract. Includes bibliographical references. Issued in print and online. Available via ProQuest Digital Dissertations.

Thesis (M.S.)--Purdue University, 2004. / Available from National Technical Information Service, Springfield, Va., 2004. Includes bibliographical references (leaves 78-80). Also available online.

Thesis (M.S.) -- University of Tennessee, Knoxville, 2006. / Title from title page screen (viewed on Sept. 18, 2006). Thesis advisor: John C. Sorochan. Vita. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xi, 117 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 115-117).

<p>The ground penetrating radar (GPR) is one of the most popular and successful sensing modalities that have been investigated for buried target detection (BTD). GPR offers excellent detection performance, however, it is limited by a low rate of advance (ROA) due to its short sensing standoff distance. Standoff distance refers to the distance between the sensing platform and the location in front of the platform where the GPR senses the ground. Large standoff (high ROA) sensing modalities have been investigated as alternatives to the GPR but they do not (yet) achieve comparable detection performance. Another strategy to improve the ROA of the GPR is to combine it with a large standoff sensor within the same BTD system, and to leverage the benefits of the respective modalities. This work investigates both of the aforementioned approaches to improve the ROA of GPR systems using statistical modeling techniques. The first part of the work investigates two large-standoff modalities for BTD systems. New detection algorithms are proposed in both cases with the goal of improving their detection performance so that it is more comparable with the GPR. The second part of the work investigates two methods of combining the GPR with a large standoff modality in order to yield a system with greater ROA, but similar target detection performance. All proposed statistical modeling approaches in this work are tested for efficacy using real field-collected data from BTD systems. The experimental results show that each of the proposed methods contribute towards the goal of improving the ROA of BTD systems.</p> / Dissertation

[pt] O método GPR Ground Penetrating Radar foi empregado nesta pesquisa visando estimar suas potencialidades como uma metodologia viável para os estudos geológicos, geotécnicos e ambientais em condições brasileiras.Para o alcance deste objetivo foram realizados ensaios em campo procurando avaliar a capacidade deste método na detecção das alterações provenientes da ação intempérica na formação do solo residual, ou seja, estimar a profundidade e espessura dos horizontes pedológicos, e o topo rochoso em um perfil geotécnio. Foram também realizados ensaios em laboratório onde fez-se o monitoramento do efeito da contaminação por hidrocarbonetos em blocos indeformados de solo residual, tanto em condições não saturadas, quanto na zona de saturação, procurando avaliar a aplicabilidade do método GPR na detecção deste tipo de contaminante.Os resultados obtidos permitiram imagear com boa resolução os contrastes bruscos, como o topo da rocha sã e blocos inclusos no solo, mas não a detecção nítida dos horizontes no perfil; e pela análise do monitoramento da contaminação, ainda é recente afirmar que o método GPR possa ser empregado com grande eficiência na detecção de contaminantes orgânicos em solo residual. / [en] The GPR method Ground Penetration Radar was used in this work, aiming at estimating its potentialities as a viable methodology to geological, geotechnical and environmental studies of Brazilian soil-rock conditions.In order to reach this objective, in situ tests have been carried out to evaluate the capability of the method in the detection of characteristics of weathering profiles in residual soils. In this case, the aim was to estimate the depth and width of pedological horizons and the bedrock in a geotechnical profile. Laboratory tests were also carried out in blocks of undisturbed residual soil of gnaissic origin. In these blocks, the effects of contamination by petroleum hydrocarbons were monitored. Both the unsaturated and the vadose zones have been monitored. The main objective in relation to the GPR was to evaluate the applicability of the method in the detection of such contaminants.The results obtained allowed to image gross contacts with good resolution such as soil-intact bedrock contacts and blocks inside soils. However, the clear detection of profile horizons were not well imaged. Regarding the contamination monitoring, it is early to affirm that the GPR method might be employed efficiently in the detection of organic contaminants in residual soils.

Across a large part of the UK highways network the carriageway and pavement foundations are drained by Highway Filter Drains (HFDs). A HFD is a linear trench constructed either at the pavement edge or central reserve, fitted with a porous carrier pipe at the base and backfilled with an initially highly porous aggregate material. This arrangement enables the swift removal of surface runoff and subsurface water from the pavement system minimising road user hazards and eliminating risk of structural damage to the pavement sub-base. The highly porous backfill filters throughout its operational life fines washed from the pavement wearing course or adjacent land. HFDs have been found to be prone to collecting near the basal sections (pipe) or surface layers contaminants or detritus that causes the filter media to gradually block. The process has been defined as HFD clogging and it has been found to lead to reduced drainage capacity and potentially severe drop of serviceability. O&M contractual agreements for DBFO projects usually propose in-service and handback requirements for all assets included in the concession portfolio. Different performance thresholds are thus prescribed for pavements, structures, ancillary assets or street lighting. Similar definitions can be retrieved for drainage assets in such agreements, and these include HFDs. Performance metrics are defined though in a generic language and residual life (a key indicator for major assets that usually drives long-term maintenance planning) is prescribed without indicative means to evaluate such a parameter. Most of pavement maintenance is carried out nowadays using proactive management thinking and engineered assessment of benefits and costs of alternative strategies (what-if scenarios). Such a proactive regime is founded upon data driven processes and asset specific ageing / renewal understanding. Within the spectrum of road management, maintenance Life Cycle Costs are usually generated and updated on an annual basis using inventory and condition data linked to a Decision Support Tool (DST). This enables the assessment and optimisation of investment requirements and projection of deterioration and of treatment impacts aligned to continuous monitoring of asset performance. Following this paradigm shift in infrastructure management, a similar structured methodology to optimise HFD maintenance planning is desired and is introduced in this thesis. The work presented enables the identification of proactive maintenance drivers and potential routes in applying a systemised HFD appraisal and monitoring system. An evaluation of Asset Management prerequisites is thus discussed linked to an overview of strategic requirements to establish such a proactive approach. The thesis identifies condition assessment protocols and focuses on developing the means to evaluate deteriorated characteristics of in service drains using destructive and non-destructive techniques. A probabilistic HFD ageing / renewal model is also proposed using Markov chains. This builds upon existing deterioration understanding and links back to current treatment options and impacts. A filter drain decision support toolkit is lastly developed to support maintenance planning and strategy generation.

No registro estratigráfico da Planície Costeira do Rio Grande do Sul estão presentes quatro sequências deposicionais de alta frequência, correspondentes a quatro sistemas do tipo laguna-barreira (I a IV). Estas sequências possuem idades pleistocênicas e holocênica e se desenvolveram em resposta a ciclos glacioeustáticos da ordem de 100 ka. O sistema costeiro holocênico, relacionado à sequência mais jovem (IV), possui setores contemporâneos com padrões de empilhamento opostos. Partindo desta observação duas hipóteses foram formuladas e investigadas. A primeira hipótese refere-se à existência de padrões de empilhamento opostos também nas sequências deposicionais mais antigas (I, II e III) e a segunda é a de que estes padrões estejam expressos na morfologia das barreiras costeiras. Uma análise geomorfológica e estratigráfica foi realizada através das geotecnologias, com o emprego do sensoriamento remoto, do geoprocessamento, de sistemas de posicionamento e do método geofísico do georradar. Os dados foram obtidos em diferentes setores da planície costeira, com enfoque na região sul, entre a fronteira com o Uruguai (Chuí) e a desembocadura da Lagoa dos Patos (Rio Grande). Nesta região, estão presentes os sistemas laguna-barreira II, III e IV, portanto estes contaram com um maior detalhamento. As interpretações realizadas permitiram estabelecer um arcabouço estratigráfico, com a definição das principais superfícies chave e tratos de sistemas, além de um modelo de evolução paleogeográfica para a região sul. A existência dos padrões de empilhamento retrogradacional, progradacional e degradacional foi constatada nas sequências deposicionais mais antigas. Ainda que estas não tenham sido datadas foi possível inferir que comportamentos distintos tenham ocorrido simultaneamente ao longo das linhas de costa relacionadas a estas sequências deposicionais. A variabilidade do comportamento dos sistemas costeiros foi verificada também através das suas características morfológicas, as quais possuem grande influência em seu potencial de preservação. Contudo, alterações posteriores, de origem erosiva e/ou deposicional, modificaram significativamente as feições originais. A aplicação das geotecnologias referidas acima, através da perspectiva da estratigrafia moderna, permitiu ampliar o conhecimento acerca dos sistemas deposicionais costeiros, especialmente das sequências relacionadas aos sistemas laguna-barreira II e III. / The stratigraphic record of Rio Grande do Sul Coastal Plain embraces four high-frequency depositional sequences corresponding to four barrier-lagoon systems (I to IV). These sequences have been developed during the Pleistocene and Holocene, in response to glacioeustatic cycles of 100 ka. The Holocene coastal system, related to the younger sequence (IV), exhibits contemporaneous sectors with opposites stacking patterns. From this observation, two hypotheses were formulated and investigated. The first hypothesis was that the opposite stacking patterns also exist in the older depositional sequences (I, II and III), and the second was that these patterns are expressed, today, in the morphology of the coastal barriers. A geomorphologic and stratigraphic analysis was performed applying various geotechnologies, like remote sensing, geoprocessing, positioning systems and the geophysical method of ground penetrating radar (GPR). The data were obtained in different sectors of the coastal plain, with a focus on the southern region between the border with Uruguay (Chui) and the inlet of Lagoa dos Patos lagoon (Rio Grande). In this region the barrier-lagoon systems II, III and IV were identified and studied in greater detail. The interpretations allowed establishing a stratigraphic framework, setting out the main key surfaces and systems tracts, and a paleogeographic model of the evolution of the southern coastal plain. The existence of retrogradational, progradational and degradacional stacking patterns was found in the older sequences. Although the absolute age of these units has not been determined, it was possible to infer that different behaviors have occurred simultaneously along the shorelines related to these depositional sequences. The variability on the behavior of the coastal systems was also verified by their morphological characteristics, which have great influence on their preservation potential. However, subsequent changes due to erosive and/or depositional events may have significantly modified the original features. The application of geotechnologies from the perspective of modern stratigraphy improved the knowledge of coastal depositional systems, especially of the sequences related to barrier-lagoon systems II and III.

O presente trabalho tem como objetivo a reconstrução da história evolutiva ao longo do Holoceno da planície costeira de cordões litorâneos estabelecidos sobre o vale fluvial do Rio Itabapoana/ES. A partir desse objetivo, foram realizadas as seguintes etapas metodológicas: Sensoriamento Remoto, Topografia, Geofísica e Geocronologia. Através da análise da imagem de satélite RapidEye, na composição colorida R5-G3-B1, foram discriminadas classes de cobertura vegetal. A relação entre a vegetação e o solo exposto proporcionou a identificação de três padrões distintos na planície costeira de cordões litorâneos. A obtenção de dados contínuos de altimetria através de um sistema global de navegação por satélite (GNSS), concentrado no caminhamento perpendicular à linha de costa, permitiu a elaboração e análise do perfil altimétrico dos cordões litorâneos, identificando-se três principais características: 1) nos primeiros 600 m tem-se um acréscimo na elevação; 2) em seguida, uma longa faixa “estável”, de pouca mudança na elevação; 3) por fim, o decréscimo da elevação nos últimos 500 m. Para caracterizar a arquitetura deposicional em subsuperfície dos cordões litorâneos, utilizou-se um Radar de Penetração no Solo (GPR) O registro obtido com GPR possibilitou a identificação de três padrões, representados pelas unidades retrogradacional e progradacional, onde o padrão de empilhamento compõe uma sequência de barreira regressiva ou progradante. Para a obtenção de uma relação cronoestratigráfica, seis amostras de sedimentos da fração arenosa de deposição eólica foram coletadas para a obtenção de idades absolutas a partir de Luminescência Opticamente Estimulada (LOE). Os cordões datados apresentaram idades holocênicas, com idades inferiores a 5.261 ± 396 anos. A integração dos resultados obtidos através dos métodos aplicados permitiu o reconhecimento de três padrões que levaram à interpretação de três fases decorrentes das variações do nível relativo do mar e do aporte sedimentar na evolução da planície. Essas fases representam os períodos de transgressão, regressão normal e regressão forçada. / The aim of this study is the reconstruction of the evolutionary history along the Holocene of the of beach ridges coastal plain established on the fluvial valley of Itabapoana River/ES. From this objective, the following methodological steps were performed: Remote Sensing, Topography, Geophysics and Geochronology. Through the analysis of the RapidEye satellite image, in the color composition R5-G3-B1, classes of vegetal cover were discriminated. The relationship between vegetation and exposed soil provided the identification of three distinct patterns of the beach ridges coastal plain. Obtaining continuous data of altimetry with a GNSS system, concentrated in the path perpendicular to the coastline, allowed the elaboration and analysis of the altimetric profile of the beach ridges. It was identified three main characteristics: 1) in the first 600 m there is an increase in elevation; 2) then along “stable” stretch, with little change in elevation; 3) lastly, the decrease of the elevation in the last 500 m. A Ground Penetrating Radar (GPR) was used to characterize the depositional architecture in the subsurface of the beach ridges The GPR record allowed the identification of three patterns, represented by the retrogradational and progradational units, in which the stacking pattern consists of a regressive or progradational barrier sequence. Six sediment samples of the sandy fraction of wind deposition were collected to obtain absolute ages from Optically Stimulated Luminescence (OSL). The dated ridges presented Holocene ages, with ages lower than 5,261 ± 396 years. The integration of the results obtained allowed the recognition of three patterns that led to the interpretation of three phases due to the variations of the relative sea level and the sedimentary budget in the evolution of the plain. These phases represent periods of transgression, normal regression and forced regression.

Ground-Penetrating Radar (GPR) is a popular non-destructive geophysical technique with a wide range of diverse applications. Civil engineering, hydrogeophysics, forensic, glacier geology, human detection and borehole geology are some of the fields in which GPR has been applied with successful or promising results. One of the most mainstream applications of GPR is landmine detection. A lot of methods have been suggested over the years to assist the landmine detection issue. Metal detectors, trained rats or dogs, chemical methods and electrical resistivity tomography are –amongst others– some of the suggested techniques. The non-destructive nature of GPR makes it an attractive choice for a problem such as demining in which contact to the ground is not allowed. The main advantage of GPR is its ability to detect both metallic and non-metallic targets. Furthermore, GPR can provide an insight regarding the nature of the target (e.g. size, burial depth, type). From the above, it is evident that GPR can potentially reduce the false alarms emerging from small metallic objects (e.g. bullets, wires, etc.) usually encountered in battle-fields and industrialised areas. Combining the robustness of the metal detector with the resolution of GPR results in a reliable and efficient detection framework which has been successfully applied in Cambodia and Afghanistan. Despite the promising, and in some cases impressive results, aspects of GPR can be further improved in an effort to optimise GPR’s performance and decrease its limitations. The validation of a GPR system is usually achieved through the so called Receiver Operation Characteristics (ROC) which depicts the probability of detection with respect to the false alarm rate. ROC is a highly nonlinear function which is sensitive to the environment as well as to the antenna unit. Landmines are typically small objects, often less than 10 cm diameter, which are shallow buried, usually in less than 10 cm depth, and sometimes almost exposed. In order for the landmines to be resolved, high frequency antennas are essential. The latter are sensitive to soil’s inhomogeneities, rough surface, water puddles, vegetation and so on. Apart from that, the near field nature of the problem makes the antenna unit part of the medium which contributes to the unwanted clutter. The above, outlines the multi-parametric nature of the problem for which no straightforward approach has yet to be proposed. Numerical modelling is a practical and solid approach to understand the physical behaviour of a system. In the case of GPR for landmine detection, numerical modelling can be a practical tool for designing and optimising antennas in synthetic but nonetheless realistic conditions. Apart from that, evaluation of a processing method only to a specific environment is not a robust approach and does not provide any evidence for its wider inclusivity and limitations. However, evaluation in different conditions can become costly and unpractical. Numerical modelling can tackle this problem by providing data for a wide range of scenarios. An extensive database of simulated responses, apart from being a practical testbed, can be also employed as a training set for machine learning. A multi-variable problem like demining, in order to be addressed using machine learning, requires a large amount of data. These must equally include all possible different scenarios i.e. different landmines, in different media with stochastically varied properties and topography. Additionally, different heights of the antenna and different depths of the landmines must also be examined. Numerical modelling seems to be a practical approach to achieve an equally distributed and coherent dataset like the one briefly described above. Numerical modelling of GPR for landmine detection has been applied in the past using generic antennas in simplified and clinical scenarios. This approach can be used in an educational context just to provide a rough estimation of GPR’s performance. In the present thesis a realistic numerical scheme is suggested in which, simplifications are kept to a minimum. The numerical solver, employed in the suggested numerical scheme, is the Finite- Difference Time-Domain (FDTD) method. Both the dispersive properties and the Absorbing Boundary Condition (ABC) are implemented through novel and accurate techniques. In particular, a novel method which implements an inclusive susceptibility function is suggested and it is shown that surpasses the performance of the previous approaches while retaining their computational efficiency. Furthermore, Perfectly Matched Layer (PML) and more specifically Convolutional Perfectly Matched Layer (CPML) is implemented through a novel time-synchronised scheme which it is proven to be more accurate compared to the traditional CPML with no additional computational requirements. An accurate numerical solver, although essential, is not the only requirement for a realistic numerical framework. Accurate implementation of the geometry and the dielectric properties of the simulated model is highly important, especially when it comes to high-frequency near-field scenarios such as GPR for landmine detection. In the suggested numerical scheme, both the soil’s properties as well as the rough surface are simulated using fractal correlated noise. It is shown, that fractals can sufficiently represent Earth’s topography and give rise to semi-variograms often encountered in real soils. Regarding the dielectric properties of the soils, a semi-analytic function is employed which relates soil’s dielectric properties to its sand fraction, clay fraction, sand density, bulk density and water volumetric fraction. Subsequently, the semi-analytic function is approximated using a Debye function that can be easily implemented to FDTD. Vegetation is also implemented to the model using a novel method which simulates the geometry of vegetation through a stochastic process. The experimentally-derived dielectric properties of vegetation are approximated –similarly to soil’s dielectric properties– with a Debye expansion. The antenna units tested in the numerical scheme are two bow-tie antennas based on commercially available transducers. Regarding the targets, three landmines are chosen, namely, PMN, PMA-1 and TS-50. Dummy landmines are used in order to obtain their geometrical characteristics and comparison between measured and numerically evaluated traces are used to tune the dielectric properties of the modelled landmines. Lastly, water puddles are realistically implemented in the model in an effort to realistically simulate high-saturated scenarios. The proposed numerical scheme has been employed in order to test and evaluate widely used post-processing methods. The results clearly illustrate that post-processing methods are sensitive to the antenna unit as well as the medium. This highlights the importance of an accurate numerical scheme as a testbed for evaluating different GPR systems and post-processing approaches in wide range of scenarios. Using an equivalent 2D numerical scheme –restricted to 2D due to computational constrains– preliminary results are given regarding the effectiveness of Artificial Neural Network (ANN) subject to an adequate and equally distributed database. The results are promising, showing that ANN can be successfully employed for detection as well as classification using only a single trace as input. A basic requirement to do so is a representative training set. This can be synthetically generated using a realistic numerical framework. The above, provide solid arguments for further expanding the proposed machine learning scheme to the more computationally demanding 3D case.