Nesta pesquisa, o metodo GPR foi empregado para localizar e mapear urnas funerarias enterradas, visando orientar as escavacoes arqueologicas e auxiliar nas medidas de protecao de sitios arqueologicos na regiao de influencia direta do aproveitamento hidreletrico de Dardanelos, proximo a Aripuana, MT. Um estudo arqueologico previo seria necessario para verificar a presenca de sitios arqueologicos, pois a regiao seria submersa, afetando todo e qualquer possivel artefato presente no sitio. Na area de influencia da usina de hidreletrica ja havia um sitio conhecido, o sitio de Dardanelos, sendo este o objeto da presente pesquisa. Dados GPR obtidos com a antena blindada de 200 MHz foram processados e analisados, e os resultados apresentados na forma de perfis 2D e em 3D na forma de depth-slices. Apos a aquisicao e processamento dos dados foram identificadas as anomalias GPR e interpretadas a fim de identificar os alvos de interesse arqueologico e raizes de arvores, evitando assim, que haja ambiguidade na caracterizacao dos alvos de interesse. A analise 3D gerada a partir dos perfis de reflexao 2D permitiu diferenciar com clareza os alvos de interesse das raizes de arvores, uma vez que nela podemos visualizar um padrao mais alongado ao inves de pontual, como e apresentado quando temos um artefato arqueologico. Ainda, atraves da conversao do tempo de percurso da onda eletromagnetica em profundidade, podemos identificar a profundidade dos alvos. Esta conversao tambem ajuda a esclarecer as ambiguidades, uma vez que as raizes sao mais rasas e os artefatos mais profundos. / In this research, GPR method was used to locate and map buried indigenous urns, aiming to guide and assist the archaeological excavations in order to guide protections acts of archaeological sites in the region directly affected by the hydroelectric of Dardanelos, near to Aripuana, MT. A preliminary archaeological study would be necessary to investigate the presence of archaeological sites, because the area would go underwater, affecting any possible artifact present on the site. In the area of influence of the hydroelectric plant there was already a known site, the site of the Dardanelos, which is the subject of this research. The GPR data obtained with shielded antenna 200 MHz were processed and analyzed, and the results presented as 2D and 3D profiles in the form of depth-slices. After processing the GPR data anomalies were identified and interpreted to identify the targets of archeological interest and roots of trees, thus avoiding ambiguity in the characterization of targets of interest. The 3D analysis generated from the 2D reflection profiles allowed to differentiate clearly the targets of interest from the roots of trees, since they can display a more elongated pattern rather than punctual, as shown when we have an archaeological artifact. Further, by converting the travel time of the electromagnetic wave in depth, we can identify the depth of targets. This conversion also helps to clarify the ambiguities, since the roots are shallower and the artifacts are deeper.

Nesta pesquisa, o metodo GPR foi empregado para localizar e mapear urnas funerarias enterradas, visando orientar as escavacoes arqueologicas e auxiliar nas medidas de protecao de sitios arqueologicos na regiao de influencia direta do aproveitamento hidreletrico de Dardanelos, proximo a Aripuana, MT. Um estudo arqueologico previo seria necessario para verificar a presenca de sitios arqueologicos, pois a regiao seria submersa, afetando todo e qualquer possivel artefato presente no sitio. Na area de influencia da usina de hidreletrica ja havia um sitio conhecido, o sitio de Dardanelos, sendo este o objeto da presente pesquisa. Dados GPR obtidos com a antena blindada de 200 MHz foram processados e analisados, e os resultados apresentados na forma de perfis 2D e em 3D na forma de depth-slices. Apos a aquisicao e processamento dos dados foram identificadas as anomalias GPR e interpretadas a fim de identificar os alvos de interesse arqueologico e raizes de arvores, evitando assim, que haja ambiguidade na caracterizacao dos alvos de interesse. A analise 3D gerada a partir dos perfis de reflexao 2D permitiu diferenciar com clareza os alvos de interesse das raizes de arvores, uma vez que nela podemos visualizar um padrao mais alongado ao inves de pontual, como e apresentado quando temos um artefato arqueologico. Ainda, atraves da conversao do tempo de percurso da onda eletromagnetica em profundidade, podemos identificar a profundidade dos alvos. Esta conversao tambem ajuda a esclarecer as ambiguidades, uma vez que as raizes sao mais rasas e os artefatos mais profundos. / In this research, GPR method was used to locate and map buried indigenous urns, aiming to guide and assist the archaeological excavations in order to guide protections acts of archaeological sites in the region directly affected by the hydroelectric of Dardanelos, near to Aripuana, MT. A preliminary archaeological study would be necessary to investigate the presence of archaeological sites, because the area would go underwater, affecting any possible artifact present on the site. In the area of influence of the hydroelectric plant there was already a known site, the site of the Dardanelos, which is the subject of this research. The GPR data obtained with shielded antenna 200 MHz were processed and analyzed, and the results presented as 2D and 3D profiles in the form of depth-slices. After processing the GPR data anomalies were identified and interpreted to identify the targets of archeological interest and roots of trees, thus avoiding ambiguity in the characterization of targets of interest. The 3D analysis generated from the 2D reflection profiles allowed to differentiate clearly the targets of interest from the roots of trees, since they can display a more elongated pattern rather than punctual, as shown when we have an archaeological artifact. Further, by converting the travel time of the electromagnetic wave in depth, we can identify the depth of targets. This conversion also helps to clarify the ambiguities, since the roots are shallower and the artifacts are deeper.

The problem of sensing a medium by several sensors and retrieving interesting features is a very general one. The basic framework of the problem is generally the same for applications from MRI, tomography, Radar SAR imaging to subsurface imaging, even though the data acquisition processes, sensing geometries and sensed properties are different. In this thesis we introduced a new perspective to the problem of remote sensing and information retrieval by studying the problem of subsurface imaging using GPR and seismic sensors. We have shown that if the sensed medium is sparse in some domain then it can be imaged using many fewer measurements than required by the standard methods. This leads to much lower data acquisition times and better images representing the medium. We have used the ideas from Compressive Sensing, which show that a small number of random measurements about a signal is sufficient to completely characterize it, if the signal is sparse or compressible in some domain. Although we have applied our ideas to the subsurface imaging problem, our results are general and can be extended to other remote sensing applications. A second objective in remote sensing is information retrieval which involves searching for important features in the computed image of the medium. In this thesis we focus on detecting buried structures like pipes, and tunnels in computed GPR or seismic images. The problem of finding these structures in high clutter and noise conditions, and finding them faster than the standard shape detecting methods like the Hough transform is analyzed. One of the most important contributions of this thesis is, where the sensing and the information retrieval stages are unified in a single framework using compressive sensing. Instead of taking lots of standard measurements to compute the image of the medium and search the necessary information in the computed image, a much smaller number of measurements as random projections are taken. The data acquisition and information retrieval stages are unified by using a data model dictionary that connects the information to the sensor data.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2003. / No abstract available

Nesta pesquisa de doutorado foi desenvolvida uma metodologia de análise e interpretação de dados GPR (Ground Penetrating Radar) empregando a tomografia de micro-ondas. Esta ferramenta foi empregada com o objetivo de detectar e estimar a geometria de alvos que simulam artefatos comumente encontrados em sítios arqueológicos brasileiros e de um alvo orgânico que simula um corpo humano em decomposição visando estudos forenses sob condições controladas. Os dados de interesse arqueológico foram adquiridos sobre o Sítio Controlado de Geofísica Rasa (SCGR) do IAG/USP. Os dados de interesse forense foram adquiridos sobre um experimento controlado conduzido no campus da USP em Pirassununga (SP), onde um porco de aproximadamente 80 kg foi enterrado e a sua decomposição foi monitorada com o método GPR ao longo de 18 meses. Os cálculos necessários para a execução da inversão dos dados GPR através da tomografia foram implementados em linguagem Matlab, juntamente com ferramentas de remoção de background que se mostraram úteis para auxiliar a interpretação dos resultados. O programa de imageamento tomográfico foi validado a partir de dados sintéticos gerados no software GprMax a partir de modelos que simulam os alvos de interesse arqueológico instalados no SCGR. A geometria dos alvos do SCGR pôde ser bem estimada, exceto pelo alvo representado pelo muro de tijolos. Feições no solo associadas às escavações para instalação dos alvos puderam ser observadas com clareza nas imagens tomográficas. A geometria do porco, bem como o processo de decomposição foram mapeados através da tomografia mesmo em condições de baixo contraste entre as suas propriedades elétricas e as do solo. Em ambos os casos estudados as imagens tomográficas de dados GPR de 270 MHz, 400 MHz e 900 MHz permitiram extrair mais informações acerca dos alvos do que pelo uso do processamento convencional. Os resultados mostram que a tomografia de micro-ondas possui um grande potencial para aplicação em sítios arqueológicos brasileiros, bem como para aplicações forenses. / In this research a methodology for analysis and interpretation of GPR (Ground Penetrating Radar) data using microwave tomography was developed. This tool was used for detection and geometry evaluation of targets which simulate artifacts usually found at Brazilian archaeological sites and also of one organic target which simulates a decomposing human body for forensic studies under controlled conditions. The data of archaeological interest were acquired on the Geophysical Test Site (SCGR) at IAG/USP. The data of forensic interest were acquired on an experiment developed at the USP campus in Pirassununga (SP) city. In this experiment a pig with about 80 kg was buried and its decomposition was monitored through GPR profiles during 18 months. The calculations required for the GPR data inversion through microwave tomography were implemented in Matlab language, with background removal tools which were helpful for the interpretation of resulting images. The tomographic imaging program was validated using synthetic data generated by the software GprMax. The models simulate targets of archaeological interest buried at the SCGR. The geometry was well estimated for all the targets, except for the brick wall. Ground features associated to excavations done for the installation of the targets were clearly observed in the tomographic images. The pig geometry and its decomposition process were mapped through microwave tomography even under conditions of low contrast between its electric properties and those from the soil. In both studied cases the tomographic images from GPR data of 270 MHz, 400 MHz and 900 MHz allowed to extract more information about the targets than just using the conventional processing. The results show that microwave tomography has a great potential to be applied at Brazilian archaeological sites, as well as for forensic applications.

Nesta pesquisa de doutorado foi desenvolvida uma metodologia de análise e interpretação de dados GPR (Ground Penetrating Radar) empregando a tomografia de micro-ondas. Esta ferramenta foi empregada com o objetivo de detectar e estimar a geometria de alvos que simulam artefatos comumente encontrados em sítios arqueológicos brasileiros e de um alvo orgânico que simula um corpo humano em decomposição visando estudos forenses sob condições controladas. Os dados de interesse arqueológico foram adquiridos sobre o Sítio Controlado de Geofísica Rasa (SCGR) do IAG/USP. Os dados de interesse forense foram adquiridos sobre um experimento controlado conduzido no campus da USP em Pirassununga (SP), onde um porco de aproximadamente 80 kg foi enterrado e a sua decomposição foi monitorada com o método GPR ao longo de 18 meses. Os cálculos necessários para a execução da inversão dos dados GPR através da tomografia foram implementados em linguagem Matlab, juntamente com ferramentas de remoção de background que se mostraram úteis para auxiliar a interpretação dos resultados. O programa de imageamento tomográfico foi validado a partir de dados sintéticos gerados no software GprMax a partir de modelos que simulam os alvos de interesse arqueológico instalados no SCGR. A geometria dos alvos do SCGR pôde ser bem estimada, exceto pelo alvo representado pelo muro de tijolos. Feições no solo associadas às escavações para instalação dos alvos puderam ser observadas com clareza nas imagens tomográficas. A geometria do porco, bem como o processo de decomposição foram mapeados através da tomografia mesmo em condições de baixo contraste entre as suas propriedades elétricas e as do solo. Em ambos os casos estudados as imagens tomográficas de dados GPR de 270 MHz, 400 MHz e 900 MHz permitiram extrair mais informações acerca dos alvos do que pelo uso do processamento convencional. Os resultados mostram que a tomografia de micro-ondas possui um grande potencial para aplicação em sítios arqueológicos brasileiros, bem como para aplicações forenses. / In this research a methodology for analysis and interpretation of GPR (Ground Penetrating Radar) data using microwave tomography was developed. This tool was used for detection and geometry evaluation of targets which simulate artifacts usually found at Brazilian archaeological sites and also of one organic target which simulates a decomposing human body for forensic studies under controlled conditions. The data of archaeological interest were acquired on the Geophysical Test Site (SCGR) at IAG/USP. The data of forensic interest were acquired on an experiment developed at the USP campus in Pirassununga (SP) city. In this experiment a pig with about 80 kg was buried and its decomposition was monitored through GPR profiles during 18 months. The calculations required for the GPR data inversion through microwave tomography were implemented in Matlab language, with background removal tools which were helpful for the interpretation of resulting images. The tomographic imaging program was validated using synthetic data generated by the software GprMax. The models simulate targets of archaeological interest buried at the SCGR. The geometry was well estimated for all the targets, except for the brick wall. Ground features associated to excavations done for the installation of the targets were clearly observed in the tomographic images. The pig geometry and its decomposition process were mapped through microwave tomography even under conditions of low contrast between its electric properties and those from the soil. In both studied cases the tomographic images from GPR data of 270 MHz, 400 MHz and 900 MHz allowed to extract more information about the targets than just using the conventional processing. The results show that microwave tomography has a great potential to be applied at Brazilian archaeological sites, as well as for forensic applications.

The objective of the proposed research is to develop structural changes to the design and application of electromagnetic (EM) sensing models to more efficiently and accurately invert EM measurements to extract parameters for applications such as landmine detection. Two different acquisition modalities are addressed in this research: ground-penetrating radar (GPR) and electromagnetic induction (EMI) sensors. The models needed for practical three-dimensional (3D) spatial imaging typically become impractically large, with up to seven dimensions of parameters that need to be extracted. These parameters include, but are not limited to target type, 3D location, and 3D orientation. The new special structures for these models exploit properties such as shift invariance and tensor representation, which can be combined with strategic inversion techniques, including the Fast Fourier Transform and semidefinite programming. The structures dramatically reduce the amount of computation and can eliminate the need to store up to five dimensions of parameters while still accurately estimating them.

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Synthetic-aperture microwave imaging with ground penetrating radar systems has become a research topic of great importance for the potential applications in sensing and profiling of civil and geophysical structures. It allows us to visualize subsurface structures for nondestructive evaluation with microwave tomographic images. This paper provides an overview of the research program, ranging from the formation of the concepts, physical and mathematical modeling, formulation and development of the image reconstruction algorithms, laboratory experiments, and full-scale field tests.

Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2003. / The imaging of platiniferous reefs in the Bushveld Igneous Complex (BIC) is of great economical and sociological importance. Borehole radar technology has been identified as a viable mapping tool to be used in day-to-day mining operations, but a critical assessment has to be made on the feasibility of this postulation. The system analysis made of the borehole radar deployed in the BIC is presented in this dissertation. The analysis is done using a specific example - the GeoMole borehole radar system. A novel procedure, based on the basic theory of electromagnetic radiation and propagation, is proposed by which the entire physical radar system can be characterized. The power transmitted by an unconventional borehole-deployed transmitter is estimated by a sequence of free space measurements, numerical simulations and theoretic derivations and approximations. Antenna transfer functions (magnitude and phase) are numerically simulated for a variety of deployment configurations. The total system transfer function of the receiver analogue and digital chain is determined. This enables the calculation of the radar's performance figures necessary to determine the applicability of the radar in a specific geological setting. A radar system is only complete when considered in its environment. The BIC is a stratified system of numerous rock layers. An in-depth study is done on the propagation of radiowaves in stratified lossy media. Only the case for non-magnetic media is discussed in this dissertation. The developed theory is used to predict the system response to a typical transmitted radar pulse in the UG1 - UG2 stratigraphy of the BIC, determine the maximum detection range of reef horizons and estimate the reflectivity of the reefs. Resolution is one of the key parameters that determine the performance and accuracy of imaging. An algorithm is proposed, developed and tested by which the resolution of the system is increased and overlapping echoes become resolvable. Even though some of the techniques are developed with a specific system in mind, the applicability of the concepts and algorithms is universal.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2004. / The use of ground penetrating radar, and especially borehole radar in underground mines, is becoming increasingly attractive. This is due to the improvements in the user friendliness of this system. Borehole radar is able to sense accurately geological faults and structures hidden inside the rock body and this information is of value to geologists. In the quest to increase the accuracy of the radar, it was realized that the borehole trajectory and surrounding rock properties are needed. This thesis discusses a rock permittivity and loss sensor which is designed to be deployed in cylindrical hard rock boreholes with diameter of about 50 mm. The sensor consists of electrodes to produce capacitance that is dependant on the rock properties, and electronics to measure this dependency. The biggest problem foreseen is that the probe will not be in direct contact with the rock body. Cylindrical Electrodes were designed using numerical simulations and physical models. Sensitivity and noise attributes received attention. Electronic components were used to sense the small capacitance produced by the electrodes. The resulting signals are slow changing "DC• voltages from which an indication of the needed properties could be extracted. The system was integrated and tested in both laboratory and mine conditions. Test-result-b,ased improvements were introduced and led to satisfactory working of the probe. However, the deployment method will need attention before this probe can be used in field conditions.