In this dissertation, a new reconstruction algorithm to estimate the complete temperature field during hyperthermia is developed which relies upon a limited amount of transient measured temperature data. The predictive capabilities of this new algorithm are then systematically studied; first using one-dimensional simulated treatments, then using three-dimensional simulated treatments, and finally applying it to hyperthermia treatments of normal canine thighs. It was found that this new algorithm predicts the complete temperature fields more accurately and robustly than the steady-state approach. In particular, it can better predict the complete temperature fields in situations where the number of unknown blood perfusion parameters are greater than the number of available temperature sensors. It was also found that the steady-state temperature field could be estimated to within 1°C if there was no measurement noise, no model mismatch, and as few as three measurement locations for seven perfusion zones. The addition of measurement noise degraded the performance of this estimation algorithm especially when the number of measurement locations was small. It was found that use of Tikhonov regularization of order zero significantly improved the performance of the algorithm and that there was an optimal choice for the regularization parameter. For the animal experiments, normal canine thighs were instrumented with one-hundred twelve thermocouples and heated to steady-state using a 6 cm planar ultrasound transducer operating at 0.5 MHz: then the power was turned off and the transient cool down temperature data was stored for later use by the reconstruction algorithm. Only a subset of the one-hundred twelve measurements was used as input to the reconstruction algorithm. The remaining measurements were used to compare the results of the reconstruction algorithm with the true temperatures. The results showed that in general the predicted perfusion and reconstructed temperature field did not change significantly as sensors were removed. However, the error was quite large for some of the situations studied particularly when only twenty-seven piecewise constant regions of perfusion were used. Increasing the number of perfusion regions reduced this error suggesting that model mismatch had contributed significantly to the error.

The LEAP (Low-Energy Antiproton) experiment is a search for cosmic-ray antiprotons in the 120 MeV to 1.2 GeV kinetic energy range. The motivation for this project was the result announced by Buffington et al. (1981) that indicated an anomalously high antiproton flux below 300 MeV; this result has compelled theorists to propose sources of primary antiprotons above the small secondary antiproton flux produced by high energy cosmic-ray collisions with nuclei in the interstellar medium. LEAP consisted of the NMSU magnet spectrometer, a time-of-flight system designed at Goddard Space Flight Center, two scintillation detectors, and a Cherenkov counter designed and built at the University of Arizona. Analysis of flight data performed by the high-energy astrophysics group at Goddard Space Flight Center revealed no antiproton candidates found in the 120 MeV to 360 MeV range; 3 possible antiproton candidate events were found in the 500 MeV to 1.2 GeV range in an analysis done here at the University of Arizona. However, since it will be necessary to sharpen the calibration on all of the LEAP systems in order to positively identify these events as antiprotons, only an upper limit has been determined at present. Thus, combining the analyses performed at the University of Arizona and Goddard Space Flight Center, 90% confidence upper limits of 3.5 x 10⁻⁵ in the 120 MeV to 360 MeV range and 2.3 x 10⁻⁴ in the 500 MeV to 1.2 GeV range for the antiproton/proton ratio is indicated by the LEAP results. LEAP disagrees sharply with the results of the Buffington group, indicating a low antiproton flux at these energies. Thus, a purely secondary antiproton flux may be adequate at low energies.

Three different types of radiometry have been examined to find the best type for solar spectral irradiance measurements requiring long-term (22 years) and ultra-high precision (0.1% uncertainty) in the near-UV, visible, and near infrared. It has been determined that the best radiometry uses the self-calibration technique developed at NBS using laser lines. Normalization techniques were applied to silicon reflectivity and quantum efficiency models for use with thermal sources and grating spectrometers. The results compared with similar laser-source calibration showed disagreement less than 0.1%. Germanium and GaAsP detectors were also investigated in the infrared and deep blue wavelengths. The germanium detector showed significant recombination loss of photogenerated carriers due to the ion implantation fabrication process. GaAsP detectors have very small dark currents ( < 1 nA), but also demonstrate significant recombination losses inside the photodiode. The possible loss mechanism of the Ge and GaAsP detectors are suggested for future study.

Salt-affected soils have undermined the effectiveness of agricultural development of considerable areas of the world, especially in the arid and semi-arid regions. This research is set out for the direct measurement of salt-affected soil. Two experiments were conducted to study the influence of different salt types and concentrations on spectral reflectance of soil. In the first experiment, five different salts (Na₂SO₄, NaHCO₃, CaCO₃, CaCl₂ and NaCl) were mixed individually with Gila soil at 0.51, 1.51 and 3.0% by weight. The second experiment was conducted to examine the spectral response of sodium sulfate and sodium bicarbonate (individually and in combination) in Gila soil at 3.0 and 6.0% by weight. Reflectance measurements were made over all soil treatments under different moisture conditions. Upon drying (24-hour after wetting), different salt types and concentrations showed different spectral response. The chemical analysis of soil samples have indicated some important relationships which influenced, directly and indirectly, the spectral reflectance of soil surfaces.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Digitized by Kansas Correctional Industries

The application of the widely used Penrnan-Monteith evapotranspiration equation to hybrid poplar trees is impossible without a valid surface resistance. The increase in applications of drip-irrigated hybrid poplar trees for wood chip stock and veneer production, as well as bioremediation, constitutes a need for estimating the evapotranspiration of these trees. To the author's knowledge, there are no published estimates of surface resistance for poplar trees. Six years of weekly soil moisture content for drip-irrigated, hybrid poplar trees were used in a water balance to compute evapotranspiration. The weekly data were adjusted with reference evapotranspiration data to compute a daily evapotranspiration. Only data that represent fully leaved hybrid poplars are used in this study and the data were screened for the effects of drainage. Additional parameters applied in this study include solar radiation, temperature, wind speed and relative humidity taken at a nearby AGRIMET Weather Station. The results of this study indicate that surface resistance values cannot be described as a function of meteorological data within the constraints of the current experiment design. The graph of poplar evapotranspiration versus surface resistance shows that for a given evapotranspiration there can be multiple rs values. This scatter is the influence of parameters other than rs within the Penman-Monteith model. The use of an instrument to directly measure the surface resistance is recommended in further studies. / Graduation date: 2000

Electrostatic discharge is of great concern to the electronics industry. It degrades and destroys large numbers of integrated circuits at every step from fabrication through packaging and testing. The goal of this research effort was the development of a device that can be used to obtain quantitative information on electrostatic discharge (ESD) in the integrated-circuit workplace. The device that was developed can be utilized in two different modes. (1) It can be used to form ESD test wafers or test chips. (2) It can be incorporated on product chips to give the ESD history of devices or monitor the process line. The technology that was examined in this work was that for floating-gate PROMS. A simple analytical model for obtaining a parameter called the ESD factor was developed. The prototype detector was designed, fabricated and tested in the Semiconductor Processing Facility of the University of Arizona. Evidence will be presented that the FLOTOX type of EEPROM functions well in its application as an ESD detector.

No description available.

No description available.