A controlled column experiment was conducted to investigate the geophysical response of gasoline spills into the partially saturated sand column. The column was 0.61 diameter (ID) and 2 m high cylindrical polyvinyl chloride, which was packed with the Borden sand to a height of 1.95 m, flushed with CO2, saturated, and drained to a height of 0.73 m. The monitoring techniques used for this experiment was DC resistivity and time domain reflectometry (TDR) methods. The column was equipped with resistivity electrodes and TDR probes, which were placed on the column wall vertically with 3 cm intervals, on opposite sides, two monitoring wells, an injection well, a manometer, an outlet/inlet system, and a vent. A total amount of 5 liters of standard API 91-01 gasoline was added to the system in steps of 1, 2, and 2 liters to examine the geophysical response to different amounts of gasoline. Measurements were taken before and after each injection and also during subsequent fluctuation of the water table. Both monitoring techniques were able to record even the minor changes in the trend of conductivity and permittivity profiles due to the addition of the small amount of gasoline during the first spill. The conductivity and permittivity profiles obtained before lowering the water level below the original level and those obtained after the water level reached to the original level do not match, which is an indication of entrapped gasoline inside the pores. Two core samples was taken from the sand symmetrically after each water table fluctuation and analyzed for total petroleum hydrocarbon (TPH) analysis and the results were compared to the conductivity and permittivity results. The conductivity profile obtained using DC resistivity method was compared to that of obtained using TDR method. The profiles match in the saturated zone where all of the pores are connected with water and therefore electrolytic conduction is predominant. In the unsaturated zone, where there is low pore water connectivity, TDR measured conductivity values are higher than those measured using the resistivity method. Water saturation values were calculated using conductivity and permittivity values before and after each injection. Different values of saturation exponent (n) were tested for Archie’s law until an appropriate value was found which gave the best water saturation from conductivity data for clean Borden sand. Then, the water saturation obtained from permittivity values using Topp’s equations for different materials were compared to that of obtained from conductivity values using Archie’s equation. Topp’s equation for 30 µm glass beads provided the best match. Furthermore, other equations developed by other researchers were examined to obtain water saturation profiles from the permittivity values; all of them overestimate the water saturation for Borden sand. The water saturation profiles after the gasoline spills obtained using both Archie’s law and Topp’s equation do not match, perhaps because both equations were developed for three-phase (water-solid-air) systems.

Quantifying and characterizing isolated tumor cells (ITCs) is of interest in surgical pathology and cytology for its potential to provide data for cancer staging, classification, and treatment. Although the independent prognostic significance of circulating ITCs has not been proven, their presence is gaining clinical relevance as an indicator. However, researchers have not established an optimal method for detecting ITCs. Consequently, this Ph.D. dissertation is concerned with the development and evaluation of dielectric spectroscopy as a low-cost method for cell characterization and quantification. In support of this goal, ultra-wideband (UWB), microwave pulse generator circuits, coaxial transmission line fixtures, permittivity extraction algorithms, and dielectric spectroscopy measurement systems were developed for evaluating the capacity to quantify B16-F10 tumor cells in suspension. First, this research addressed challenges in developing tunable UWB circuits for pulse generation. In time-domain dielectric spectroscopy, a tunable UWB pulse generator facilitates exploration of microscopic dielectric mechanisms, which contribute to dispersion characteristics. Conventional approaches to tunable pulse generator design have resulted in complex circuit topologies and unsymmetrical waveform morphologies. In this research, a new design approach for low-complexity, tunable, sub-nanosecond and UWB pulse generator was developed. This approach was applied to the development of a novel generator that produces symmetrical waveforms (patent pending 60/597,746). Next, this research addressed problems with transmission-reflection (T/R) measurement of cell suspensions. In T/R measurement, coaxial transmission line fixtures have historically required an elaborate sample holder for containing liquids, resulting in high cost and complexity. Furthermore, the algorithms used to extract T/R dielectric properties have suffered from myriad problems including local minima and half-wavelength resonance. In this dissertation, a simple coaxial transmission line fixture for holding liquids by dispensing with the air-core assumption inherent in previous designs was developed (patent pending 60/916,042). In addition, a genetic algorithm was applied towards extracting dielectric properties from measurement data to circumvent problems of local minima and half wavelength resonance. Finally, in this research the capacity for using dielectric properties to quantify isolated B16-F10 tumor cells in McCoy's liquid medium was investigated. In so doing, the utility of the Maxwell-Wagner mixture formula for cell quantification was demonstrated by measuring distinct dielectric properties for differing volumes of cell suspensions using frequency- and time-domain dielectric spectroscopy.

An essential component for evaluating the performance of a mine site after its closure includes the tracking of water movement through mine waste such as tailings and overburden. A critical element of this evaluation is the measurement of the volume of water stored in the closure landform. The objective of this project was to design a time domain reflectometry (TDR) device that could be used to measure the volumetric water content of a soil profile to depths of 10 to 20 m. Upon completion of this project, the device will be integrated onto ConeTec’s cone penetration testing (CPT) shaft for initially monitoring Syncrude Canada Limited’s northeastern Alberta oil sands mine site. The objective of this project will be achieved through at least two phases of research and development; this thesis concentrates on the first phase. In this phase, research focused on prototype development through laboratory testing to determine appropriate TDR probe geometries and configurations that could be integrated onto a CPT shaft. Considerations also had to be made for protecting the integrity of the probe during field use and mitigating the effects of highly electrically conductive soils common in reclaimed mine sites. A number of different prototype designs were initially investigated in this research, leading to the development of a refined prototype for advanced testing. Testing for the project was carried out first in solutions of known dielectric constants and salinities, and then proceeded to soils with a range of known water contents and salinities. Good quality electrical connections were found to be crucial for generating waveforms that were easy to interpret; bad connections resulted in poor results in a number of cases. Decreased probe sensitivity was observed in response to increased rod embedment within the probe variants. A far greater decrease in sensitivity was seen in the results of the fully sheathed rods, although the sheathing was effective for extending the range of the probe in electrically conductive testing conditions. Despite poor results that were seen in some of the tests, overall the results were promising. In particular, results from the push-test showed that the probe was able to monitor changes in water content with depth.

Thesis (M.S.)--Ohio University, March, 2004. / Title from PDF t.p. Includes bibliographical references (leaves 73-75).

Orientador: Edson Eiji Matsura / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-06T21:37:31Z (GMT). No. of bitstreams: 1 MestasValero_RogerManuel_M.pdf: 1264659 bytes, checksum: bbb3d9d1a7966c854866628251702d0c (MD5) Previous issue date: 2006 / Resumo: O aumento na utilização de estufas para produção agrícola e o conseqüente cultivo em recipientes fez com que houvesse uma substituição de solos por substratos para plantas. Em cultivos em substratos, o pequeno volume e o baixo efeito tampão podem ocasionar prejuízos na produção, mas também podem aumentar as chances de sucesso agronômico. Conseqüentemente um sistema sensível como este deve ser continuamente monitorado, a fim de se obter bons resultados. É preciso avaliar metodologias que determinem a umidade (?) e condutividade elétrica (CE) nos substratos, com maior rapidez e in situ, mantendo boa correlação com o método padrão. Das várias propostas para determinação da umidade e CE dos meios porosos, a técnica da TDR (Reflectometria no domino do tempo) vem despertando cada vez mais interesse, pois apresentam características desejáveis, como a mensuração em tempo real e a possibilidade de leituras automatizadas, porém apresenta como desvantagens seu alto custo e sua necessidade de calibração. Apesar da técnica da TDR para determinação de umidade em solos ser mais estudada é necessário novos conhecimentos acerca desta técnica quando se utiliza substratos. O objetivo deste trabalho foi de avaliar o uso da técnica TDR na estimativa de umidade e condutividade elétrica em dois substratos orgânicos: casca de pinus (CP) e fibra de coco (FC), na qual, determinou-se as principais características físicas destes substratos (densidade, granulometria e curva de retenção de umidade). A calibração da TDR foi feita através de duas metodologias; umedecimento e secagem do substrato. Já para estimativa da condutividade elétrica utilizou-se modelos matemáticos desenvolvidos por Rhoades et al., (1976). Os resultados mostraram que os valores da constante dielétrica (Ka) e da umidade volumétrica (?) dos substratos puderam ser ajustados através de equações polinomiais cúbicas, estatisticamente significativas a nível de1%. Conclui-se que o uso da TDR para estimativa de umidade em substratos é possível, desde que se faça a calibração para cada um. Além disso, houve correlação da condutividade elétrica determinada pela TDR com a condutividade elétrica determinada pelo condutivímetro no extrato de solução dos substratos, possibilitando o uso da TDR na estimativa de condutividade elétrica nos substratos estudados / Abstract: The increasing use of greenhouse in agricultural production and the resulting grow of container crops is determining the substitution of soil for substrates. The small container volume and the low tampon effect can cause failures in substrate crops production, but also has the potential to increase the opportunities of agronomic success. Therefore, this sensible production system must be continuously monitored in order to obtain good results. So, more precise and fast methodologies that determine in situ the water content and electrical conductivity (EC) in substrates has to be evaluated, when compared to standard method. From the several proposals methods to determinate water content and EC in a porous means, the technique of the TDR (Time Domain Reflectometry) show some desirable characteristics, like real time measurements and the possibility of automated readings. Some disadvantages of this technique are the high initial cost and necessity of calibration. Although, the number of information of TDR use in soil moisture determination its use in substrate still needs more developments. The objective of this work was to evaluate the use of TDR technique in the measurement of water content and electrical conductivity in two organic substrates: pine bark (CP) and coconut fiber (FC). The specific gravity, particle size distribution and water content retention curve of both substrates were determined. The calibration of the TDR was done using two methodologies: dryness and saturation cycles. In the electrical conductivity determination it was applied mathematical models developed by Rhodes et al. (1976). The results showed that the values of water content and dielectric constant of the substrates can be mathematically adjust in cubic polynomial equations with 1% significant level. Therefore, the use of TDR technique of the TDR is feasible since a calibration curve is determined for each substrate. In addition, there was correlation of the electrical conductivity determined by the TDR with the electrical conductivity determined in the extract saturation by conductivimeter, making possible the use of the TDR in the EC measuring of the studied substrates / Mestrado / Agua e Solo / Mestre em Engenharia Agrícola

Here the nature of gas phase processes and their implications for flow and transport were examined using a pilot-scale, 2-dimensional, laboratory tank instrumented for direct, in situ trapped gas measurements. Experimental conditions mimicked an unconfined, homogeneous sand aquifer with horizontal flow. Key areas of investigation included i) trapped gas dissolution following a water table fluctuation; and ii) gas phase dynamics within a hydrocarbon plume experiencing dissolved gas production via biodegradation. In the first experiment, dissolution occurred as a diffuse, wedge-shaped front propagating down-gradient in the tank over time, with enhanced dissolution at depth. Front advancement at the deepest monitoring point was 4.1 - 5.7x faster. This dynamic, depth-dependent pattern was mainly attributed to increased dissolved gas solubility. An estimated 12% increase in quasi-saturated hydraulic conductivity (Kqs) also contributed to greater dissolution at depth. Overall, the dissolution front near the water table advanced 1 m down-gradient in 344 days, suggesting that gas trapped shallowly will likely persist for significant periods of time. The utility of total dissolved gas pressure sensors for simple in-well measurements to detect trapped gas and monitor its dissolution were also demonstrated. During the second experiment, biodegradation occurred under variable redox conditions, ranging from denitrification to methanogenesis. Significant in situ increases in trapped gas were observed within the tank over 330 days. Maximum gas saturations never exceeded 27% of pore volume even during continued dissolved gas production, indicating ebullition upon reaching a gas phase mobilization threshold. Consequently, associated reductions in Kqs were restricted to a factor of 2 or less, but still appeared to alter the groundwater flow field. While trapped gas increases within the biodegradation plume were expected, declines in gas saturations were also observed. Thus, the overall pattern of trapped gas growth exhibited high spatial and temporal variability. Influencing factors included changes in hydrocarbon inputs and microbial controls on redox zonation, in addition to ebullition and changes in groundwater flow; emphasizing that gas phase growth in contaminant plumes will be highly complex and dynamic in the natural systems. Given the impacts on hydraulic conductivity, and the fate and transport of volatile compounds, an improved understanding of quasi-saturated conditions will be beneficial for various groundwater applications, from recharge and paleoclimate studies to site characterizations and remediation strategies. / Dissertation / Doctor of Philosophy (PhD)

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Dielectric constant is a physical property of soil that is often measured using non-invasive geophysical techniques in subsurface characterization studies. A proper understanding of dielectric responses allows investigators to make measurements that might otherwise require more invasive and/or destructive methods. Previous studies have suggested that dielectric models could be refined by accounting for the contributions of different types of mineral constituents that affect the ratio and properties of bound and bulk water. This study tested the hypothesis that the dielectric responses of porous materials are mineral-specific through differences in surface area and chemistry. An experimental design was developed to test the dielectric behavior of pure quartz sand (Control), quartz sand/kaolin clay mixtures and ferric oxyhydroxide coated quartz sand. Results from the experiments show that the dielectric responses of quartz-clay and iron oxyhydroxide modified samples are not significantly different from the pure quartz Control. Increasing clay content in quartz sands leads to a vertical displacement between fitted polynomials. The results suggest that the classic interpretation for the curvature of dielectric responses appears to be incorrect. The curvature of dielectric responses at low water contents appears to be controlled by unknown parameters other than bound water. A re-examination of the experimental procedure proposed in this study and past studies shows that a properly designed study of bound water effects on dielectric responses has not yet been conduct / Master of Science