Due to the rapid nature of microwave heating, the microbiological safety of foods prepared in the microwave has been in question for several years. Because foods are heated from the inside out and are strictly governed by their own internal properties such as ionic content, moisture level and specific heat, work must be done to further master control of such properties so microwave cooking can be more predictable, controlled and ensure control pathogens. This study concentrated on the effect of fat content, evaporative cooling and food type on the rate of food borne pathogen survival rates in microwave heated foods. Foods investigated in this study included fresh, raw broccoli spears; a regular, whole muscle breaded chicken patty and a fat free, breaded, formed chicken patty; and raw ground beef patties at three differing fat percentages. All foods were tested in triplicate. A Sharp® 1000W Light-Duty Commercial Microwave Oven was used to treat inoculated samples according to their recommended cooking times. Two sets of samples were treated, one wrapped with Saran™ Wrap and the other without wrap. F-values were determined for each product. Raw ground beef patties at fat contents of 30%, 15% and 7%, heated for the same time had F-values ranging from 0.03 to 126.20. The lower the fat content, the lower the lethality. Regular and fat free chicken tenders had similar patterns. F-values for fresh broccoli indicted that vegetative pathogens survived the recommended microwave process. Covering in Saran™ Wrap had some preventive effect on evaporative cooling depending on the food tested and significantly (p < 0.05) increased most F-values. Inoculated pack studies were performed in triplicate on each food with Listeria monocytogenes, Salmonella and Escherichia coli O157:H7. Survival was determined by presence or absence of growth of each pathogen after enrichment. Listeria monocytogenes survived in all samples except for the 30% fat ground beef patties. The Salmonella species had a lower survival rate; however, it was still present in uncovered 15% fat ground beef, covered 7% fat ground beef, uncovered chicken patties (both types) and in all broccoli samples tested. E. coli O157:H7 survived in all samples except the 30% fat ground beef samples. Results indicate that higher fat contents seem to ensure lower rates of pathogen survival. This was especially true for the raw ground beef, which had received no prior processing other than the grinding of the whole muscle. There were fewer survival differences in the preprocessed, frozen chicken patties. Both were shown to support no pathogen survival in covered samples, except the fat free chicken patties. Listeria monocytogenes was shown to consistently survive the suggested cooking time in these samples. This is consistent with expectations that fat free food samples would display more survival than regular fat samples. Overall, covering samples with Saran™ had little effect on pathogen survival rates. There were survival differences in some covered and uncovered samples consistent with expectations that covered samples would show less survival than uncovered, but further work including more samples would be necessary to ensure that the covered or uncovered variable made the true difference in pathogen survival. Finally, broccoli demonstrated consistent pathogen survival in all categories of testing. This indicates microwave oven prepared vegetables could be a prime source of pathogen transmission to consumers. Further work needs to concentrate on determining the correct processing times and parameters that need to be met to ensure safe food. / Master of Science

This work consisted of an experimental investigation of the formic acid (HCOOH) molecule's rotational spectrum. Measurements of line widths were obtained for J = 5, 12, 13, 19, and 20 for a pressure range from 1 to 10 microns. A linear behavior between Av and p was observed as predicted by theory. The line width parameter Avp was observed to depend on the quantum number J. Hard sphere collision diameters b1 were calculated using the obtained AvP values. These deduced hard sphere values were found to be larger than the physical size of the molecule. This result was found to be in general agreement with other investigation in which long range forces (dipole-dipole) dominate.

The SMAPVEX12 (Soil Moisture Active/Passive Validation Experiment 2012) was carried out over the summer of 2012 in Manitoba, Canada. The goal of the project was to improve the accuracy of satellite-based remote sensing of soil moisture. Data were gathered during a 42-day field campaign with surface measurements on 55 different agricultural fields in south-central Manitoba. The extended duration of the campaign, contrast in soil textures, and variety of crop types over the study region provided an excellent range of soil moisture and vegetation conditions. The study fields ranged from bare to fully vegetated, with volumetric soil moisture levels spanning a range of almost 50%. Remotely sensed data were collected on 17 days by aircraft at 1.4 Ghz with a microwave radiometer at two different resolutions. Observed brightness temperatures from the radiometer showed a typical inverse relationship to the near simultaneous soil moisture measurements from the field. Field-by-field relationships using all sampling dates with both soil and emissivity data were all shown to be significant with the exception of two of the pasture fields and a soybean field. Linear regressions across multiple fields and by flight lines also had statistically significant slopes. The significance of all these relationships improved with the removal of pasture fields from the analysis. On most fields, the sensitivity (slope) of the relationship and correlation coefficient (R2) between emissivity and observed soil moisture increased when vegetation and roughness effects were taken into account. The b parameter that relates vegetation water content to optical depth in the tau-omega model was optimized using the collective slope and R2 values of the individual fields. A b parameter value of 0.06 for horizontal polarization and 0.13 for vertical polarization were found to be optimal across the range of all fields in this analysis. / May 2016

For size miniaturization and cost reduction, the design of dual band devices has become an emerging research area in recent years. A desirable dual-band solution should offer size compactness, high performance (e.g. low insertion loss) and compatible with conventional printed circuit broad (PCB) technology, especially microstrip lines. / In this research, several new devices, including rat-race coupler, power divider and crossover junction, capable of operating at dual frequency bands are proposed. These structures involve only simple branch-line sections and a minimal number of shunt stubs. All characteristic impedances are ranged from 20 O to 100 O. Most designs can operate with wide frequency spacing between the two bands. These designs offer low insertion loss as well as good return loss performances, and are small in size, in compared to the broadband approach. For design purposes, explicit closed-form equations are derived for the evaluation of circuit parameters. In addition, the usable range of these devices with respect to frequency band separation is examined. For verification, various prototypes are constructed by using microstrip technology and in-house fabrication facilities. Both simulated and measured results are presented and compared with state-of-the-art examples. / Microwave passive couplers are widely used in microwave and millimeter-wave applications and communication systems. Common examples are branch line coupler, rat race coupler, power divider, and crossover junction. They are used for the dividing, combining and re-directing of signal power. / Very often, a passive coupler utilizes simple quarter-wavelength transmission lines for implementation which will lead to narrow-band operation. Therefore, it is difficult to deploy such circuit for wide-band or multi-band applications. Multi-section topologies may be used to broaden the operating bandwidth, with which the major drawbacks are enlarged circuit size and the requirement of extreme high (or low) branch-line characteristic impedances. Both are not attractive for mass and low cost production. Conventional design approaches are, therefore, not suitable for modern communication systems with multi-band operation. / Wong, Fai Leung. / Adviser: Michael Cheng. / Source: Dissertation Abstracts International, Volume: 73-06, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 118-122). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

在現代通信系統，無線服務的需求不斷增加，帶動了通信系統，支持多標準的操作需要。 雙波段或多波段操作幾乎都是必要的，能夠提供這些操作的微波器件已成為減小尺寸和降低成本有吸引力的解決方案。 / 分支線耦合器是用於微波和毫米波應用的最流行的無源電路之一。它們通常用於平衡放大器和混頻器去實現良好的回波損耗以及隔離。其中一個至關重要的部份是設計一個可以靈活作多波段分配的分支線耦合器。 / 傳統上，完全平面的實施，雙波段分支線耦合器可以通過短截線，階梯阻抗線，耦合線等不同的分佈式結構實現。不同的設計方案已在這幾年來出現。窄帶操作和複雜的電路設計，是以前的設計的主要缺點。雖然，在理論上，多節技術可以拓寬帶寬，但它的主要缺點是電路的面積變大了及使用極端低/高傳輸線阻抗。因此，它不是一個大量和低成本生產的解決方案。 / 在這項研究中，設計了全新的並增強了性能的雙波段分支線耦合器(零分貝和三分貝的功率分裂)。這些設計能在兩個指定的頻帶有不平等的工作帶寛。通過正確選擇雙頻四分之一波長阻抗變換器的電氣長度和線路阻抗，傳輸相位斜率將能夠被控制並給出帶寬不對稱的特點，其性能可以進一步擴展，涵蓋了廣泛的應用。 / 以上所有設計都只需要單層線路版的制作及可實現的傳輸線阻抗。應用奇/偶模式分析所給出設計公式。這些設計具有低損耗，佈局靈活，緊密的尺寸大小的特性。這些設計己經使用標準微帶的結構實現其特點，其結果得到了實驗結果的進一步驗證。分支線耦合器只需要更小的節數就能實現相同的性能。 / In modern communication systems, the increasing demand for wireless services has driven the need for communication systems that support multi-standard operations. Dual-/Multi- band operation is almost a necessity and the adoption of microwave multi-band devices has become an attractive solution towards size and cost reduction of RF frontend designs. / Branch-line coupler is one of the most popular passive circuits used for microwave and millimeter-wave applications. They are commonly used in balanced amplifiers, phase-shifter, mixer and frequency multipliers for achieving good return loss, as well as isolation. It is therefore essential to have a branch-line coupler with multi-band operation. / Traditionally, for fully planar implementation, the construction of dual-band branch-line couplers are usually accomplished by distributed structures based upon shunt-stub, stepped-impedance line, coupled line etc. Narrow-band operation and circuit complexity are the major drawbacks for these previous designs. Although, in theory, the available bandwidth may be broadened by multi-section configurations, its major tradeoffs are the enlarged circuit size as well as the extreme line dimensions involved. Therefore, it is not preferable to mass and low cost production. / In this research, advanced designs of dual-band branch-line coupler (0 dB and 3 dB power splitting) with enhanced performances are presented. By proper selection of the number of sections, electrical lengths and line impedances of appropriate branch-lines of the coupler, its performance can be further extended to cover a wide range of applications. / All the proposed circuits require only single-layer fabrication and realizable line impedance. Closed form design formulas are made available by the application of even/odd- mode formulation. They feature low loss, flexible layout and compact size. The designs have been implemented and characterized using standard microstrip, and verified experimentally. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Yeung, Sung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 92-95). / Abstracts also in Chinese. / Abstract --- p.ii / 摘要 --- p.iii / Acknowledgement --- p.iv / Table of Content --- p.v / Lists of Figures --- p.viii / Lists of Tables --- p.xii / Chapter Chapter 1 --- : Introduction --- p.1 / Chapter 1.1 --- Research Motivation and Objective --- p.1 / Chapter 1.2 --- Original Contribution --- p.3 / Chapter 1.3 --- Research Approach, Assumptions and Limitations --- p.4 / Chapter 1.4 --- Overview of the Thesis Organization --- p.5 / Chapter Chapter 2 --- : Review of Microwave Coupler Design --- p.6 / Chapter 2.1 --- Coupler Design Fundamental --- p.6 / Chapter 2.1.1 --- Coupler Design with Equal Power Splitting --- p.7 / Chapter 2.1.2 --- Coupler Design with Unequal Power Splitting --- p.12 / Chapter 2.1.3 --- 0-dB Coupler or Crossover --- p.16 / Chapter 2.1.4 --- Coupler Design with Size Miniaturization --- p.18 / Chapter 2.1.5 --- Wide Band Coupler Design --- p.21 / Chapter 2.2 --- Dual-Band and Multi-Band Branch-line Coupler --- p.25 / Chapter 2.2.1 --- Dual-Band Couplers Based on Composite Right/Left-Handed Transmission Line --- p.25 / Chapter 2.2.2 --- Dual-Band Couplers with Shunt Stubs --- p.28 / Chapter 2.2.3 --- Dual-Band Coupler Based on Stepped-Impedance-Stub-Line --- p.30 / Chapter 2.2.4 --- Dual-Band Coupler with Port Extensions --- p.33 / Chapter 2.2.5 --- Tri-Band Coupler Based on Matching Network --- p.35 / Chapter 2.2.6 --- Multi-passband Branch-line Coupler Design --- p.37 / Chapter 2.3 --- Summary --- p.39 / Chapter Chapter 3 --- : A Novel Dual-band 0-dB Branch-line Coupler Design --- p.40 / Chapter 3.1 --- Proposed Circuit --- p.40 / Chapter 3.2 --- Analysis of Single-band 0-dB Branch-line Coupler --- p.43 / Chapter 3.3 --- Single- to Dual-band Conversion --- p.52 / Chapter 3.4 --- Experimental Results --- p.55 / Chapter 3.5 --- Summary --- p.58 / Chapter Chapter 4 --- : A Novel Dual-band 3-dB Branch-line Coupler with Unequal Bandwidth --- p.59 / Chapter 4.1 --- Proposed Dual-band Impedance Transformer: --- p.59 / Chapter 4.2 --- Single-band 3-dB Coupler Design --- p.65 / Chapter 4.3 --- Dual-band 3-dB Coupler Design --- p.70 / Chapter 4.4 --- Experimental Results --- p.76 / Chapter 4.4.1 --- Equal bandwidth design --- p.76 / Chapter 4.4.2 --- Unequal bandwidth design --- p.78 / Chapter 4.5 --- Summary --- p.81 / Chapter Chapter 5 --- : A Novel Dual-band 0-dB Branch-line Coupler Design with Unequal Bandwidth --- p.82 / Chapter 5.1 --- Proposed Circuit --- p.82 / Chapter 5.2 --- Analysis and Formulation --- p.84 / Chapter 5.3 --- Simulation Results --- p.85 / Chapter 5.4 --- Experimental Results --- p.87 / Chapter 5.5 --- Summary --- p.89 / Chapter Chapter 6 --- : Conclusion and Recommendation for Future Work --- p.90 / Chapter 6.1 --- Conclusion --- p.90 / Chapter 6.2 --- Recommendation for future work --- p.91 / References --- p.92 / Author’s Publications --- p.96 / Chapter Appendix 1: --- Brief Summary of Design Approaches of Hybrids Couplers --- p.97 / Chapter Appendix 2: --- Transformation between S- and ABCD- parameters for two-port network --- p.99

Thesis (Ph.D.)--City University of Hong Kong, 2006. / "Submitted to Department of Electronic Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy" Includes bibliographical references.

The propagation characteristics of a new coupled fin line structure, with asymetrical, rectangular, top and bottom housings, is evaluated by using the modal analysis technique. The boundary Green's function of the structure, relating the surface currents to the electric fields is derived by using this technique. The propagation characteristics, i.e. propagation constant and impedances, of the structure are determined by implementing Galerkin's procedure and the results are presented for a wide range of possible structure dimensions. A CAD compatible, quasistatic analysis based on conformal mapping of the rectangular housing structure and known coplanar waveguide results is also presented. The results of the quasistatic analysis are shown to be in good agreement with the fullwave simulation at low frequencies. / Graduation date: 1993

Naphthenic acids (NAs) are natural constituents of bitumen and crude oil, and predominantly obtained as the by-product of petroleum refining with variable composition and ingredients. Naphthenic acids are composed of alkyl-substituted cycloaliphatic carboxylic acids, with smaller amounts of acyclic aliphatic acids. Naphthenic acids become a significant part of the tailings pond water (TPW) after separation from oil sands material. NAs are soluble in water and are concentrated in TPW as a result of caustic oil sands extraction processes. Tailings ponds near the Athabasca oil sands region near Fort McMurray, Alberta, Canada are contaminated with a variety of toxic organic compounds released in industrial effluent from the oil extraction processes. NAs are among the major water contaminants in those regions because of their toxicity and environmental recalcitrance. They may enter surface water systems due to erosion of riverbank oil sands deposits and through groundwater mixing. Significant environmental and regulatory attention has been focused on the naphthenic acids fraction of oil sands material to address these challenges and potential hazards. Biological, chemical, and photolytic treatments of water contaminated with NAs have been studied, but are either time consuming or involve significant capital investment. There is a growing need to develop more efficient and cost-effective treatment methods. Based on existing literature, microwave and photocatalysis for degradation of naphthenic acids in water may be one solution. A knowledge gap exists in determining the effect of microwave energy and/or photocatalysis on the rate and extent of NAs degradation in contaminated water.<p> Part of this work included evaluation of the physical and chemical properties of NAs. Dielectric properties, important for designing a microwave system, were investigated. Effects of temperature, concentration, and frequency of microwaves on the dielectric properties of NA-water mixtures were studied and were used in designing the treatment systems for NAs. Three laboratory scale systems, (1) photocatalysis, (2) microwave, and (3) microwave assisted photocatalysis systems were designed and developed. Experiments were conducted to determine the NA degradation efficiency of these systems for both commercially available Fluka NAs and those extracted from oil sand process water (OSPW). Effects of water source (deionised and river water) and use of TiO2 catalyst in the degradation process, were also investigated. Degradation kinetics for total NAs as well as individual z-family were calculated.<p> Results show that the three developed treatment systems were able to degrade NAs at a faster rate than the methods reported to date. The concentration of higher molecular weight NAs (z = -4 to -12) decreased more significantly than the lower molecular weight NAs in all the three treatment systems. Toxicity assessments of the NAs samples before and after treatment indicated that photocatalysis and microwave assisted photocatalysis systems decreased the toxicity of Fluka and OSPW NAs completely (up to 5 min IC50 v/v > 90%). The microwave system reduced the toxicity of water containing Fluka NAs from high (5 min IC50 v/v = 15.85%) to moderate (5 min IC50 v/v = 36.45%) toxicity. However, a slight increase in toxicity was noted post-treatment in OSPW NAs.<p> Microwave-assisted photocatalysis was the most rapid degradation system for OSPW NA extracts in water with a half-life of 0.56 h in the presence of TiO2. The microwave system degraded OSPW NAs in water at a more moderate half-life of 3.32 h. The photocatalysis system was the slowest with a half-life of 3.99 h under similar conditions.<p> High and ultra high resolution analysis of NA sample, estimations of cost and further efficiency related research of the developed systems to treat water with microbial load along with chemical contaminants are recommended for future work to further validate these treatment systems.

Naphthenic acids (NAs) are natural constituents of bitumen and crude oil, and predominantly obtained as the by-product of petroleum refining with variable composition and ingredients. Naphthenic acids are composed of alkyl-substituted cycloaliphatic carboxylic acids, with smaller amounts of acyclic aliphatic acids. Naphthenic acids become a significant part of the tailings pond water (TPW) after separation from oil sands material. NAs are soluble in water and are concentrated in TPW as a result of caustic oil sands extraction processes. Tailings ponds near the Athabasca oil sands region near Fort McMurray, Alberta, Canada are contaminated with a variety of toxic organic compounds released in industrial effluent from the oil extraction processes. NAs are among the major water contaminants in those regions because of their toxicity and environmental recalcitrance. They may enter surface water systems due to erosion of riverbank oil sands deposits and through groundwater mixing. Significant environmental and regulatory attention has been focused on the naphthenic acids fraction of oil sands material to address these challenges and potential hazards. Biological, chemical, and photolytic treatments of water contaminated with NAs have been studied, but are either time consuming or involve significant capital investment. There is a growing need to develop more efficient and cost-effective treatment methods. Based on existing literature, microwave and photocatalysis for degradation of naphthenic acids in water may be one solution. A knowledge gap exists in determining the effect of microwave energy and/or photocatalysis on the rate and extent of NAs degradation in contaminated water.<p> Part of this work included evaluation of the physical and chemical properties of NAs. Dielectric properties, important for designing a microwave system, were investigated. Effects of temperature, concentration, and frequency of microwaves on the dielectric properties of NA-water mixtures were studied and were used in designing the treatment systems for NAs. Three laboratory scale systems, (1) photocatalysis, (2) microwave, and (3) microwave assisted photocatalysis systems were designed and developed. Experiments were conducted to determine the NA degradation efficiency of these systems for both commercially available Fluka NAs and those extracted from oil sand process water (OSPW). Effects of water source (deionised and river water) and use of TiO2 catalyst in the degradation process, were also investigated. Degradation kinetics for total NAs as well as individual z-family were calculated.<p> Results show that the three developed treatment systems were able to degrade NAs at a faster rate than the methods reported to date. The concentration of higher molecular weight NAs (z = -4 to -12) decreased more significantly than the lower molecular weight NAs in all the three treatment systems. Toxicity assessments of the NAs samples before and after treatment indicated that photocatalysis and microwave assisted photocatalysis systems decreased the toxicity of Fluka and OSPW NAs completely (up to 5 min IC50 v/v > 90%). The microwave system reduced the toxicity of water containing Fluka NAs from high (5 min IC50 v/v = 15.85%) to moderate (5 min IC50 v/v = 36.45%) toxicity. However, a slight increase in toxicity was noted post-treatment in OSPW NAs.<p> Microwave-assisted photocatalysis was the most rapid degradation system for OSPW NA extracts in water with a half-life of 0.56 h in the presence of TiO2. The microwave system degraded OSPW NAs in water at a more moderate half-life of 3.32 h. The photocatalysis system was the slowest with a half-life of 3.99 h under similar conditions.<p> High and ultra high resolution analysis of NA sample, estimations of cost and further efficiency related research of the developed systems to treat water with microbial load along with chemical contaminants are recommended for future work to further validate these treatment systems.

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