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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.
241

Structural Condition Assessment of a Parking Deck using Ground Penetrating Radar

Neupane, Garima 03 August 2020 (has links)
No description available.
242

(Re)constructing Homescapes: “Archaeological remote sensing” and ground-truthing of the Walker Place homestead at Spirit Hill Farm, Tate County, Mississippi

Griffin, Gabriel 09 August 2022 (has links) (PDF)
This thesis focuses on an early nineteenth-century homestead known as the Walker Place homestead at Spirit Hill Farm in northern Mississippi. The goal of this thesis is to conduct a ground-penetrating radar (GPR) and shovel test survey to explore how changing landscapes simultaneously (re)create and destroy senses of place or Homescapes. Homescapes have received little attention in the field of archaeology and have not been applied to Euro-American Homescapes. I apply this theoretical construct in a novel way as a venture to further develop an avenue in archaeology to be collaborative and understand the past in a way that accurately reflects the realities of the past. I utilize historical records, oral histories, archaeological materials, and GPR to deepen our understanding of this site and to demonstrate the value of holistic archaeology and collaborating with the descendant community.
243

Comparison of Compact Very High Frequency (VHF) Antennas for Small Airborne Ground Penetrating Radar

Livingston, Tayler Austen 25 July 2023 (has links) (PDF)
UHF bands because more penetration can be achieved at low frequencies. Consequently, large antennas are required, which limits their use for small airborne applications. This thesis explores various GPR antenna designs for a bi-static system that are at least operational from 225 MHz to 255 MHz and suitable for small airborne applications. The 3D electromagnetic simulation software Ansys high-frequency structure simulator (HFSS) was used to simulate various sizes of strip dipole, triangular bowtie, half elliptical bowtie, and elliptical bowtie antennas. Several physical models were constructed to validate the return loss simulation results. Additionally, simulation data is included for a wire dipole and a helical antenna. The helical antenna proved to be too large for small airborne application, so focus was placed on the dipole and bowtie designs. The performance of the dipole and bowtie antenna models are compared by size, weight, return loss (𝑆11), peak gain, and the transmit-to-receive isolation. Out of the fourteen simulated models, twelve meet the bandwidth requirement with an average weight of 0.23 lbs. It is found that the strip dipole exhibited wider bandwidth characteristics than the triangular, elliptical, and half elliptical bowtie models, while maintaining similar weight and size. The smallest strip dipole model is 50 mm x 528 mm x 1 mm, weighs 0.17 lbs, and is operational from 225 MHz to 283 MHz. Two strip dipole test antennas were fabricated and tested. Test results confirm the simulation predictions.
244

Validity of Holocene Analogs for Ancient Carbonate Stratigraphic Successions: Insights from a Heterogeneous Pleistocene Carbonate Platform Deposit

Hazard, Colby 01 February 2015 (has links) (PDF)
Observations of modern carbonate depositional environments and their accompanying depositional models have been used for decades in the reconstruction and interpretation of ancient carbonate depositional environments and stratigraphic successions. While these Holocene models are necessary for interpreting their more ancient counterparts, they inherently exclude important factors related to the erosion, diagenesis, and ultimate preservation of sediments and sedimentary structures that are ubiquitous in shallow marine carbonate environments. Andros Island, Bahamas is an ideal location to examine the validity of Holocene conceptual models, where geologically young (Late Pleistocene) limestones can be studied immediately adjacent to their well-documented modern equivalents. For this study, two 3D ground-penetrating radar (GPR) datasets (200 MHz and 400 MHz) were collected at a schoolyard in northwest Andros. These surveys reveal the geometries and internal characteristics of a peloidal-oolitic sand wave and tidal channel in unprecedented detail. These two prominent features are underlain by low-energy lagoonal wackestones and packstones, and are bordered laterally to the northwest by wackestones-packstones intermixed with thin sheets of peloidaloolitic grainstone. A deeper radar surface is observed at approximately 6 m depth dipping gently to the west, and is interpreted to be a karstified exposure surface delineating the base of a complete depositional sequence. Interpretation of the 3D radar volumes is enhanced and constrained by data from three cores drilled through the crest and toe of the sand wave, and through the tidal channel. This study is the first of its kind to capture the complex heterogeneity of a carbonate depositional package in three dimensions, where various depositional environments, sedimentary structures, and textures (mudstone to grainstone) have been preserved within a small volume.The results from this study suggest that the degree of vertical and lateral heterogeneity in preserved carbonate successions is often more complex than what can be observed in modern depositional environments, where sediments can generally only be observed in two dimensions, at an instant in time. Data from this study demonstrate the value of using two overlapping GPR datasets at differing resolutions to image the internal characteristics of a complete carbonate depositional package in three dimensions. From these datasets, a depositional model similar to other Holocene and Pleistocene carbonate depositional models is derived.
245

Multi-Scale Neotectonic Study of the Clear Lake Fault Zone in the Sevier Desert Basin (Central Utah)

Heiner, Brandon D. 21 January 2014 (has links) (PDF)
A multi-scale high-resolution geophysical and geological study was conducted in the Sevier Desert, central Utah, found within the Colorado Plateau-Basin and Range Transition Zone. The region is marked by with Quaternary volcanics and faulting as young as 660 yr B.P., with many fault scarps thought to have the potential for 7+ magnitude earthquakes. Three locations within the Sevier Desert which represent three different tectonic expressions of possible faulting at the surface were selected. These include a location found within surface sedimentation, a location with surface sedimentation and sub-surface basalts and a location with basalts, at the surface with very limited sedimentation. A suite of geophysical data were obtained including the use of P-wave, SH-wave, ground-penetrating radar (GPR). Auger holes, microprobe glass analysis, and mapping information were also completed in order to constrain and gain a more complete understanding of the sub-surface structure. These data were used to determine if there are sub-surface expressions of the possible surface scarps and if all the faults within the fault zone have the same structural style. The possible surface fault expressions were found to be connected to sub-surface fault expressions but with differing results within both sediments and basalts. Our data show that a multi-scale approach is needed to obtain a complete view of tectonic activity. The area faulting in the Sevier Desert penetrates at depth involving multiple complex styles that include some faulting that cuts recent lava flows and some that do not. The evidence also indicates that in at least some area faulting was episodic and others may be single events having implications on level of activity and hazard.
246

Ultra-wideband antenna design for microwave imaging applications. Design, optimisation and development of ultra-wideband antennas for microwave near-field sensing tools, and study the matching and radiation purity of these antennas within near field environment.

Adnan, S. January 2012 (has links)
Near field imaging using microwave in medical applications has gain much attention recently as various researches show its high ability and accuracy in illuminating object comparing to the well-known screening tools such as Magnetic Resonance Imaging (MRI), digital mammography, ultrasound etc. This has encourage and motivate scientists continue to exploit the potential of microwave imaging so that a better and more powerful sensing tools can be developed. This thesis documents the development of antenna design for microwave imaging application such as breast cancer detection. The application is similar to the concept of Ground Penetrating Radar (GPR) but operating at higher frequency band. In these systems a short pulse is transmitted from an antenna to the medium and the backscattered response is investigated for diagnose. In order to accommodate such a short pulse, a very wideband antenna with a minimal internal reflection is required. Printed monopole and planar metal plate antenna is implemented to achieve the necessary operating wide bandwidth. The development of new compact printed planar metal plate ultra wide bandwidth antenna is presented. A generalized parametric study is carried out using two well-known software packages to achieve optimum antenna performance. The Prototype antennas are tested and analysed experimentally, in which a reasonable agreement was achieved with the simulations. The antennas present an excellent relative wide bandwidth of 67% with acceptable range of power gain between 3.5 to 7 dBi. A new compact size air-dielectric microstrip patch-antenna designs proposed for breast cancer detection are presented. The antennas consist of a radiating patch mounted on two vertical plates, fed by coaxial cable. The antennas show a wide bandwidth that were verified by the simulations and also confirmed experimentally. The prototype antennas show excellent performance in terms the input impedance and radiation performance over the target range bandwidth from 4 GHz to 8 GHz. A mono-static model with a homogeneous dielectric box having similar properties to human tissue is used to study the interaction of the antenna with tissue. The numerical results in terms the matching required of new optimised antennas were promising. An experimental setup of sensor array for early-stage breast-cancer detection is developed. The arrangement of two elements separated by short distance that confined equivalent medium of breast tissues were modelled and implemented. The operation performances due to several orientations of the antennas locations were performed to determine the sensitivity limits with and without small size equivalent cancer cells model. In addition, a resistively loaded bow tie antenna, intended for applications in breast cancer detection, is adaptively modified through modelling and genetic optimisation is presented. The required wideband operating characteristic is achieved through manipulating the resistive loading of the antenna structure, the number of wires, and their angular separation within the equivalent wire assembly. The results show an acceptable impedance bandwidth of 100.75 %, with a VSWR < 2, over the interval from 3.3 GHz to 10.0 GHz. Feasibility studies were made on the antenna sensitivity for operation in a tissue equivalent dielectric medium. The simulated and measured results are all in close agreement.
247

Optimizing Remote Sensing Methodology for Burial Mounds in the United States and United Kingdom

Corkum II, Alexander C. January 2019 (has links)
Within the archaeological record ‘mounds’ are often ubiquitous. They are common in many ancient cultures, and they vary in size, construction techniques and use. This research is focused upon optimizing the use of remote sensing for the non-invasive study of mounds both in the United States and the United Kingdom. This thesis presents three representative earthen mound sites and proposes a comprehensive and modular survey methodology to guide the planning and execution of a mound survey tailored to the unique requirements presented by the cultural resource at a particular location. In doing so, the research has provided optimized approaches to high resolution three-dimensional topographic models using a variety of digital methods. These models have been shown to accurately capture the variability of the modern ground surface, which is of vital importance to the management of the mounds. Furthermore, these models have proved vital for integrating geophysical methods into the holistic workspace, thereby providing a better archaeological understanding of the below ground remains. Every mound surveyed presented different challenges, and therefore had to be approached in a slightly different way. However, the general methodology was highly effective for both characterizing below-ground archaeological and natural anomalies, and for assessing the state of preservation of all mounds surveyed. As a result, a flowchart has been generated for non-invasive assessment of mounds in general. If followed, this will allow the production of a “snapshot” of the mound or mound group at a fixed point in time with the resolution necessary to produce useful and insightful interpretation. While this research focuses on the application of geophysical and topographic survey in the United Kingdom and United States to a mound or mound group, this methodology and the associated outcomes can be valuable more globally not only for archaeology, but also heritage management.
248

Quantitative, non-destructive estimates of forest coarse root biomass using 3-D ground-penetrating radar (GPR)

Molon, Michelle M. 10 1900 (has links)
<p>We evaluated 3-D imaging of coarse root structure and biomass using ground-penetrating radar (GPR). GPR surveys were conducted in a white pine forest in southern Ontario, Canada. GPR profiles were obtained across two test plots (6 and 17 m<sup>2</sup> area), using 1-GHz GPR and a MEMS (micro-electro-mechanical systems) accelerometer. Test plot surveys evaluated the effects of micro-topography, soil moisture content, and root diameter and spacing. In addition, with the aid of the outcome of the control test plots two other plots (25 and 400 m<sup>2 </sup>area) were surveyed with varying line sample spacing to investigate the restraints on resolution brought about by line sampling density.</p> <p>Accounting for antenna tilt is necessary to determine an accurate and more precise position of root mass. The antenna tilt was >45<sup>o</sup> pitch, >28<sup>o</sup> roll and up to 10<sup>o</sup> yaw due to surface micro-topography of the forest floor. Vector 3-D imaging enhanced the diffraction amplitude (15.5% increase) and centralized the position of the root. Radial surveys provided root continuity and produced better root imaging.</p> <p>GPR largely underestimates coarse root biomass when a line spacing of 25 cm is used. However similar results are found with smaller line spacing (12.5 cm). A maximum line spacing of 10 cm provided continuous root structure and differentiation of roots spaced 10 cm apart and greater. A sampling line spacing of 5 cm and an inline sampling interval of 0.5 cm in low soil moisture conditions provided the detection of roots that were a minimum of 1.4 cm in diameter.</p> / Master of Science (MSc)
249

In-Situ Recycling: Applications, Guidelines, and Case Study for Local Governments

Bartku, Elaine Cleare 23 July 2014 (has links)
This thesis investigates the application of In-Situ Recycling and provides guidelines for localities to aid in the selection of recycling methods, as well as documents a local government's experience with Cold In-Place Recycling. The recycling methods discussed in this study include Cold In-Place Recycling (CIR), Hot In-Place Recycling (HIR), and Full Depth Reclamation (FDR). These methods are performed onsite and in-place in a continuous process of milling, mixing, and placement. The In-Situ Recycling guidelines include suggestions based on: traffic characteristics, existing road condition, distress types, road access, local climate, road geometry, and other road characteristics. The guidelines are based on information from sources including NCHRP Synthesis 421, American Recycling and Reclamation Association (ARRA), FHWA, and state agencies with recycling experience. This study also resulted in documenting obstacles that localities may face when in-situ recycling, as well as the impact of limited experience with recycling. The study also evaluated the construction of Cold In-Place Recycled pavement sections in Christiansburg, VA, using Falling Weight Deflectometer (FWD) and Ground Penetrating Radar (GPR). Additionally, using the FWD and GPR data, alternate recycled designs were proposed in addition to a cost comparison to a conventional design. / Master of Science
250

Contribuições dos métodos GPR e Eletromagnético Indutivo em estudos de sítios arqueológicos de sambaquis costeiros no Estado de Santa Catarina / GPR and Electromagnetic Induction Methods Contributions in Studies of Coastal Sambaqui Archaeological Sites in Santa Catarina State.

Rodrigues, Selma Isabel 25 February 2010 (has links)
Nesta pesquisa são apresentadas as contribuições dos métodos GPR e eletromagnético indutivo (equipamento EM-38) nos estudos de sítios arqueológicos de sambaquis costeiros Jabuticabeira II, Santa Marta IV, V, VII e VIII, e Encantada III, localizados no município de Jaguaruna, litoral centro-sul de Santa Catarina. Estes sítios são caracterizados por acúmulos de conchas carbonáticas construídos por sociedades do período pré-colonial (7,5 a 1,3 mil anos AP). Os estudos foram desenvolvidos, visando o mapeamento de artefatos de interesse arqueológico e de estruturas estratigráficas que auxiliem a compreensão do processo construtivo e funcional destes sítios. A interpretação dos resultados GPR foi apoiada nas modelagens numéricas GPR 2D e nas imagens 3D e integrada com os levantamentos EM-38, e tiveram como objetivos orientar as escavações arqueológicas. Os resultados permitiram encontrar alvos e artefatos arqueológicos, reduziram os custos no processo exploratório e preservaram o patrimônio histórico. Complementando o processo de interpretação integrada, os perfis estratigráficos e as análises granulométricas dos sedimentos provenientes dos furos de sondagens foram importantes para a definição dos ambientes de deposição onde os sambaquis estão assentados, corroborando de maneira significativa com as pesquisas em desenvolvimento no litoral de Santa Catarina. Em termos metodológicos, as antenas GPR blindadas de 200 MHz propiciaram um melhor compromisso entre a profundidade de investigação e a resolução vertical das camadas geo-arqueológicas, e a implementação da técnica de aquisição radial permitiu um mapeamento detalhado do sítio Jabuticabeira II de forma rápida, cobrindo uma grande área. Por outro lado, com o método eletromagnético indutivo (EM-38), a correção do efeito topográfico dos dados melhorou os contrastes de condutividade elétrica entre as estruturas arqueológicas e o background, permitindo assim, que os alvos pontuais, antes mascarados pela influência da topografia, fossem realçados. Com relação aos resultados geofísicos em estudos geoarqueológicos, no sambaqui Jabuticabeira II, foi possível caracterizar a geometria de uma estrutura geológica, associada a um paleo-canal e a deposição dos sedimentos em barras de pontal; mapear alvos arqueológicos e metálicos contemporâneos; traçar os limites do sítio; imagear uma camada conchífera, camadas antrópicas recentes e a profundidade do nível dágua; detectar a presença de dois sistemas deposicionais, paleolaguna e paleoduna, bem como delimitar o assentamento do sítio sobre estes ambientes por meio das informações das análises granulométricas dos sedimentos coletados nos furos de sondagens. Nos sambaquis de Santa Marta IV, V, VII e VIII, a integração dos dados GPR e EM38 permitiram o mapeamento de diversos alvos de grande importância para os estudos arqueológicos, tais como, paleofogueiras, sepultamentos e concentração de materiais cerâmicos e líticos, bem como feições geológicas, tais como, estruturação de camadas e paleotômbolos. Além disso, a redução do efeito topográfico sobre os dados de condutividade elétrica (EM-38) permitiu relacionar as regiões anômalas com um paleofogueira e uma concentração de material cerâmico. No sambaqui Encantada III, duas fortes anomalias GPR, caracterizadas por reflexões hiperbólicas, estavam associadas: i) a uma estrutura escura pontual, caracterizada como um bolsão de conchas carbonáticas; e ii) a presença de uma raiz de árvore concrecionada, que embora não seja de interesse arqueológico, é significativa, pois serve como um bom exemplo de ambiguidade na interpretação de dados geofísicos. Também foi possível delimitar o assentamento do sítio sobre os sedimentos da paleo-laguna, evidenciado pelas análises granulométricas dos sedimentos. / In this study, GPR and electromagnetic induction (EM-38 instrument) methodcontributions in coastal sambaqui archaeological sites (Jabuticabeira II, Santa Marta IV, V, VII and VIII as well as Encantada III) are presented. These sites are placed in Jaguaruna, Santa Catarina center-south coast. They are characterized by accumulation of carbonate shells built by societies in pre-colonial period (7.5 to 1.3 thousand years BP). The studies were developed aimed at mapping archaeological artifacts and stratigraphic structures that help to understand constructive and functional process of these sites. The interpretation of GPR results was supported by 2D GPR numerical modeling, 3D images and integrated with EM-38 surveys. They had as objectives to guide archaeological excavations. The results allowed finding archaeological targets and artifacts, reduced costs in exploratory process, and preserved historical heritage. Complementing integrated interpretation process, stratigraphic profiles and granulometric analysis of sediment from sounding drifts were important for defining the deposition environments where sambaquis (shell mounds) are settled, significantly supporting in developing research on Santa Catarina coast. Methodologically, 200 MHz shielded GPR antennas provided a better agreement between depth of investigation and vertical resolution of geoarchaeological layers, and the implementation of radial acquisition technique allowed a quickly detailed mapping of Jabuticabeira II site, covering a large area. Furthermore, with electromagnetic inductive method (EM-38), the topographic effect correction of data has improved the contrast in electrical conductivity between archaeological structures and background. Thus, punctual targets before masked by topography influence were highlighted. Regarding geophysical results in geoarchaeological studies, in Jabuticabeira II sambaqui, it was possible to characterize the geometry of a geological structure associated with a paleochannel and sediment deposition in point bars; to map archaeological and contemporary metal targets; to trace site boundary; to image shell layer, recent anthropic layers and water level depth; to detect the presence of two deposicional systems, paleolagoon and paleodune as well as to delimit the settlement site on these environments through information of granulometric analysis of sediments collected in sounding drifts. In Santa Marta IV, V, VII and VIII sambaquis, GPR and EM-38 data integration allowed mapping several targets of great importance for archaeological studies, such as paleofires, burials and concentration of ceramic and litic material as well as geological features, such as layer structuring and paleotombolos. Moreover, the reduction of topographic effect on electrical conductivity data (EM-38) allowed relating anomalous regions with a paleofire, and a concentration of ceramic material. In Encantada III sambaqui, two strong GPR anomalies characterized by hyperbolic reflections were associated with: i) a dark punctual structure, characterized as a pocket of shell carbonate, and ii) the presence of a concretion tree root that is significant, despite not of archaeological interest, because it serves as a good example of ambiguity in geophysical data interpretation. It was also possible to delimit the settlement site on paleolagoon sediments, evidenced by granulometric analysis of sediments.

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