The research reported herein describes the study activities performed by University of Central Florida (UCF) on behalf of the Town of Jupiter Water Utilities (Town). The Town recently changed its water treatment operations from a combination of reverse osmosis (RO), lime softening (LS) and anion-exchange (IX) to a combination of RO, IX and nanofiltration (NF). Although this treatment change provided enhanced water to the surrounding community in terms of better contaminant removal and reduced DBP formation potential, integration of the NF process altered finished water quality parameters including pH, alkalinity and hardness. There was concern that these changes could result in secondary impacts related to accelerated corrosion of distribution system components and subsequent regulatory compliance. In addition, replacement of the LS process altered the in-plant blending operations by creating an unstable intermediate blend composed of RO and IX waters. There were concerns that this intermediate blend was affecting the integrity of in-plant hydraulic conveyance components. UCF developed a corrosion monitoring study to assess the potential impacts related to internal corrosion, water quality and regulatory compliance after integrating NF into the existing water supply. The intended purpose was to further highlight the complexities of corrosion, describe a unique approach to corrosion monitoring as well as offer various recommendations for corrosion control in a system that relies on a blended water supply. Research was conducted in three phases to address the in-plant and distribution system corrosion issues separately and identify appropriate corrosion control treatment alternatives. The three test phases included: a baseline conditions assessment to iv compare corrosion of the intermediate RO-IX blend with the finished water blend (ROIX-NF); an in-plant corrosion control evaluation; and a distribution system corrosion control evaluation. A test apparatus was constructed and operated at the Town’s facilities to monitor corrosion activity of mild steel, copper and lead solder metal components. The test apparatus consisted of looped PVC pipe segments housed with electrochemical probes and metal coupons to monitor corrosion rates of the metallic components. Electrochemical probes containing metal electrodes were used to obtain instantaneous corrosion rates by means of the Linear Polarization Resistance (LPR) technique while the metal coupons were gravimetrically evaluated for weight loss. The electrochemical probes permitted daily monitoring of each metal’s corrosion rates while metal coupons were analyzed at the conclusion of testing and used for comparison. Different test waters flowed through the corrosion rack according to each test phase and relative corrosion rates were compared to evaluate corrosion control techniques. Study findings indicated that the intermediate blend was more corrosive, in general, then the final blend; however, research also indicated that the final blend of water was increasing lead and copper concentrations within the distribution system. An orthophosphate corrosion inhibitor was evaluated for in-plant corrosion control. The inhibitor’s performance was assessed by comparing mild steel corrosion rates with and without the chemical. In addition, secondary impacts related to introduction of the chemical were evaluated by pre-corroding the metallic components prior to the introduction of the inhibitor. Results indicated that the inhibitor marginally decreased corrosion rates and increased the turbidity of the water supply. Based on these v observations, it was concluded that the inhibitor was not a viable solution for in-plant corrosion control. To resolve in-plant corrosion issues, recommendations were made for modification of in-plant blending operations to eliminate the corrosive intermediate blend from the process allowing the RO, IX and NF treated waters to be blended in a common location. The effectiveness of a poly/ortho blended phosphate chemical inhibitor was evaluated for reducing lead and copper corrosion to resolve distribution corrosion issues. A 50/50 poly/ortho blend was selected because of its analogous use in similar municipal water facilities. Metallic corrosion rates, particularly lead and copper, were compared with and without the inhibitor to assess the performance of the chemical. Like the previous test phase, the metallic components were pre-corroded prior to the chemical’s introduction to determine if secondary impacts could result from its presence. Results indicated that lead and copper corrosion rates were lower in the presence of the inhibitor, and secondary impacts related to increased turbidity were not observed for this chemical. Based on these results, it was recommended that a poly/ortho blended phosphate be used to decrease lead and copper corrosion within the Town’s distribution system.

This thesis comprises linear polarization measurements on gamma rays emitted from the previously observed 1.984, 2.572, 2.969 and 3.059 MeV levels of ²²Na using a Ge(Li) Compton polarimeter. Consistency with previous measurements on parameters characterizing these levels was first checked before assigning J^π = 2⁺ for the 1.984 MeV level and determining that both 2.969 MeV and 3.059 MeV levels have positive parity. Investigation of the 2.572 MeV level produced inconsistency with some previous work which had indicated a 2⁻ assignment. However, except for some pickup reaction work. the polarization measurement is consistent with all former measurements and indicates a 2⁺ assignment. / Thesis / Master of Science (MSc)

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8-band k.p theory was applied to bulk GaN and InN. The optical transitionintensity was computed and results show > 80-90% degree of polarization inthe direction of compression. Polarization switching is observed when strainwas reversed from compressive to tensile. 6 band k.p theory was used tostudy InGaN quantum dot/GaN elliptical pyramid structures. The opticaltransition intensity was calculated for different elongations of the pyramid.Elongation of the pyramid gives rise to a small polarization in the directionof the pyramid elongation. The optical transition intensity was calculatedfor elongated quantum dots and was strongly in uencing the polarization inthe direction of the quantum dot elongation, with a degree of polarization of >90%.

In this dissertation, the operation of dual-linear polarized antennas is considered in order to provide ideal performance suited for several applications including polarimetric synthetic aperture radar (SAR), wireless and satellite communications. The underlying objectives realized in this work are reported as design realizations of dual-linear polarized antennas with low cross polarization patterns and high isolation between ports that employ special properties of the electromagnetic metamaterial (MTM) structures. Some of these key properties appear as negative permittivity, negative permeability, negative refractive index, and antiparallel nature of the phase velocity and the group velocity. The antenna design is carried out at two frequencies, 5.5 GHz and 10 GHz, and key physical issues that affect the operation of dual-linear polarization operation antennas are treated in light of electromagnetic MTM properties. It’s well known that a dual linear polarized antenna poses a big challenges such as cross polarization patterns and high mutual coupling between two input ports. Therefore, these drawbacks are key topic that receive significant attention in literature which reports on how to mitigate these drawbacks, however, at the expense of complexity of the antenna structures. The MTM structures have received considerable coverage in antenna research for obtaining size reduction, directivity enhancement, and beam steering. For this purpose, different MTMs structures are chosen in this thesis for achieving additional improvements, while keeping the antenna design as simple as possible, something which is very difficult to accomplish using conventional design methods. / In der folgenden Dissertation wird der Einsatz von zweifach linear polarisierten Antennen zur idealen Ausführung von verschiedenen Anwendungen, einschließlich von polarimetrischen Synthetic Aperture Radar (SAR), kabellose und satellitengestützte Kommunikation, diskutiert. Die Ziele dieser Arbeit werden dargestellt durch die Gestaltung von zweifach linear polarisierten Antennen mit gering Kreuz-Polarisationsmustern und die starke Isolation zwischen den Ports durch die einzigartigen Eigenschaften der Strukturen des elektromagnetischen Metamaterials (electromagnetic metamaterial; MTM). Einige dieser Eigenschaften treten als negative Permittivität, negative Permeabilität, negativer Brechungsindex und als antiparallel Richtungen (Gegenvektor) der Phasen-und Gruppengeschwindigkeit auf. Somit wird die Antennengestaltung auf zwei Frequenzen übertragen, 5,5GHz und 10 GHz, und die Ausführung der zweifach linearen Polarisation wird durch die elektromagnetischen Eigenschaften des MTM illustriert. Weil die Kreuzpolarisationsmuster und starke gegenseitige Koppelung zwischen zwei Input-Ports bei einer zweifach linear polarisierten Antenne große Schwierigkeiten bereiten, werden diese im Großteil der Fachliteratur als Schwerpunkte gesetzt, was zu einer Milderung der Nachteile führte, jedoch dafür die Komplexität der Antennenstruktur zunahm. Die Vielfalt an MTM ist ein bedeutender Teil im Bereich der Antennenforschung einschließlich der Größenverkleinerung, der Verbesserung der Richtcharakteristik und der Strahlensteuerung. Für diesen Zweck werden in dieser Dissertation verschiedenste MTM Strukturen ausgewählt um weitere Verbesserungen der Antennenstruktur zu ermöglichen und gleichzeitig die Einfachheit der Struktur zu bewahren, was mit konventionellen Gestaltungsmethoden nur schwer zu erreichen ist.

Numerous methods have been developed to measure corrosion potential relating to chloride infiltration in concrete, including an emerging application of electrochemical impedance spectroscopy (EIS). EIS involves measurements of electrical impedance to evaluate the corrosion potential of steel reinforcement in concrete. With EIS, current is injected vertically into the concrete bridge deck between the surface and the embedded reinforcing steel, usually the top mat, to evaluate the degree to which the reinforcing steel is protected from chloride infiltration by the entire bridge deck system. The objectives of this research were to 1) investigate the sensitivity of EIS measurements obtained at various frequencies to specific deck properties, 2) recommend a particular frequency or range in frequency at which impedance measurements can differentiate among various levels of corrosion protection for reinforcing steel in concrete bridge decks, and 3) compare impedance values measured at the recommended frequency(ies) to more traditional test measurements relating to corrosion of reinforcing steel in concrete bridge decks. This research involved impedance testing of 25 concrete slabs, divided into five sets. The effects of sealant presence, curing time, temperature, moisture content, cover depth, water-to-cementitious materials ratio, air content, chloride concentration, and epoxy coating condition on individual impedance measurements were evaluated. For the controlled laboratory experiments, sealant presence, curing time, temperature, moisture content, cover depth, water-to-cementitious materials ratio, air content, and epoxy coating condition were shown to have a statistically significant effect on impedance measurements, with p-values less than 0.05. The statistical analyses indicated that impedance testing in the frequency range of approximately 100 Hz to 1 kHz would be expected to provide the best data about the degree to which the reinforcing steel is protected from chloride infiltration by a bridge deck system. In this frequency range, a high level of differentiation among levels of corrosion protection is expected, and a high speed of data collection is also possible. For the uncontrolled laboratory experiments, a single frequency of 200 Hz was selected for impedance testing. Statistical analyses were performed to compare impedance with more traditional test measurements relating to corrosion of reinforcing steel in concrete bridge decks. Longitudinal and transverse cover, dry and wet resistivity, dry and wet half-cell potential, dry linear polarization, and chloride concentration were determined to be correlated with impedance, with p-values less than 0.15.

Aims: This paper extends previous studies in modeling time varying linear polarization due to axisymmetric magnetic fields in rotating stars. We use the Hanle effect to predict variations in net line polarization, and use geometric arguments to generalize these results to linear polarization due to other mechanisms. Methods: Building on the work of Lopez Ariste et al., we use simple analytic models of rotating stars that are symmetric except for an axisymmetric magnetic field to predict the polarization lightcurve due to the Hanle effect. We highlight the effects for the variable line polarization as a function of viewing inclination and field axis obliquity. Finally, we use geometric arguments to generalize our results to linear polarization from the weak transverse Zeeman effect. Results: We derive analytic expressions to demonstrate that the variable polarization lightcurve for an oblique magnetic rotator is symmetric. This holds for any axisymmetric field distribution and arbitrary viewing inclination to the rotation axis. Conclusions: For the situation under consideration, the amplitude of the polarization variation is set by the Hanle effect, but the shape of the variation in polarization with phase depends largely on geometrical projection effects. Our work generalizes the applicability of results described in Lopez Ariste et al., inasmuch as the assumptions of a spherical star and an axisymmetric field are true, and provides a strategy for separating the effects of perspective from the Hanle effect itself for interpreting polarimetric lightcurves.

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Previous studies have demonstrated the sensitivity of the amplitude of the microwave radiation-induced magnetoresistance oscillations to the microwave polarization. These studies have also shown that there exists a phase shift in the linear polarization angle dependence. But the physical origin of this phase shift is still unclear. Therefore, the first part of this dissertation analyzes the phase shift by averaging over other small contributions, when those contributions are smaller than experimental uncertainties. The analysis indicates nontrivial frequency dependence of the phase shift. The second part of the dissertation continues the study of the phase shift and the results suggest that the specimen exhibits only one preferred radiation orientation for different Hall-bar sections. The third part of the dissertation summarizes our study of the Hall and longitudinal resistance oscillations induced by microwave frequency and dc bias at low filling factors. Here, the phase of these resistance oscillations depends on the contact pair on the device, and the period of oscillations appears to be inversely proportional to radiation frequency.