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This dissertation investigates the application of the frequency-scanned beam of a microstrip leaky wave antenna (LWA) to track humans in the two-dimensional (2-D) range-azimuth plane. The history, operating principles and frequency-scanned properties of a microstrip LWA are first reviewed. The basic concept of using a microstrip LWA to track humans is verified by designing, building and testing a broadband microstrip LWA, developing the necessary processing algorithm, and collecting data using a vector network analyzer. A number of topics are then investigated to further advance the concept. First, the idea of combining the frequency-scanned antenna with a short-pulse ultra-wideband (UWB) radar is developed to realize a portable, real-time system for human tracking. The radar concept and the components of the system are discussed in detail. Line-of-sight and through-wall measurements of a human subject are carried out to demonstrate the performance. Second, a new LWA structure is proposed to achieve a narrower azimuth beam, which requires both a small leaky-wave attenuation constant and a long aperture. The transverse resonance method (TRM) is applied to analyze the proposed structure and the results are verified with measurements of a built prototype. Third, a new signal processing technique, compressive sensing, is applied to further improve the resolution in both the azimuth and down range dimensions. The technique is tested with simulation and measurement data and is shown to produce sharper target responses in both the down range and azimuth dimensions. Lastly, the radar cross-section (RCS) of a microstrip LWA is studied. The antenna mode scattering and structural mode scattering are modeled separately. A ray picture is provided to explain the observed time-domain features using the group delay of the leaky wave. / text

In this work, a low-complexity two-dimensional (2D) frequency-scanned antenna is proposed to image a human using a Doppler radar. It consists of two back-to-back, air-filled microstrip leaky wave antennas (LWAs). The frequency-scanned pattern of the microstrip LWA is used to determine the target bearing in one dimension. Two such elements are used as an interferometer to determine the target bearing in the other dimension. In order to pack two LWAs closely, a design is proposed to achieve a minimal disturbance on the azimuth and elevation beam patterns. The design is measured with both static and Doppler targets to demonstrate the capability to form 2D frontal images. To investigate the potential performance of using the proposed antenna to image a human, a simulator that includes a dynamic human signature model and the frequency-scanned antenna pattern is developed. A radar waveform that is different from that used for the measurement conducted with simple Doppler targets is proposed. A simple five-point human model is tested first to understand the capability of the antenna to image a human. Next, the antenna design and the radar processing parameters are studied to improve the image quality. Simulated frontal images of a walking human are generated and discussed. With a redesigned antenna and new radar processing steps, simulation shows that frontal imagery of a human undergoing motion can be generated. / text

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The US dairy industry loses approximately $1.2 billion due to heat stress related production losses annually. It was formerly believed that heat-stressed lactating dairy cattle produce less milk because they consume less feed. It has since been established that the reduction of feed intake is only responsible for about 50% of the reduced milk yield in HS cows. It is believed that HS increases gastrointestinal permeability (GIP), resulting in microbial components leaking from the lumen of the gastrointestinal tract into underlying tissue and stimulating an immune response. The immune response is suspected to alter overall metabolism, and milk production specifically, by diverting nutrients away from the mammary gland and other non-essential processes to support immune system activation. Topics examined herein focus on identifying markers to assess gastrointestinal permeability and the influence of heat stress on GIP and nutrient metabolism. The first study utilized an in vitro rumen fermentation system to determine if lactulose, sucralose, and D-mannitol could persist in an in vitro rumen culture. Lactulose could not be quantified in the rumen fluid matrix, D-mannitol was rapidly degraded, and sucralose concentrations did not change after 48 h of incubation, establishing sucralose as an indigestible marker in mature ruminants. The second study utilized a pair feeding design to directly assess the effect of HS on GIP, milk yield, and immune activation by lipopolysaccharide (LPS). HS cows (n=7) were exposed to a temperature-humidity index (THI) value of 74-80 for 4 d. The pair-fed thermoneutral cows (PFTN, n=8) were exposed to a constant THI of 64 with their intake matched to the HS cows. HS lowered milk yield without altering GIP, measured using orally dosed sucralose as a permeability marker, or eliciting an LPS related immune response. Jejunal mucosal scrapings were harvested from each cow, tight junction proteins were quantified, and no differences were detected. Lack of treatment responses in GIP marker recovery and tight junction protein abundance indicate that increased GIP may not be a driving force behind production losses in HS dairy cows. The third study focused on energy substrate utilization during HS with the objective of determining if tissue-level energy substrate metabolism could be influencing glucose sparing mechanisms. Metabolic flexibility of skeletal muscle, liver, and mammary tissue was assessed after 4 d of HS. It was determined that HS reduced skeletal muscle metabolic flexibility and did not alter liver and mammary metabolic flexibility. This indicates that skeletal muscle has a greater dependency on glucose as an energy substrate, which may decrease the pool of glucose available for lactose synthesis in lactating cows. Finally, the last study had the objective of assessing branched-chain amino acid (BCAA) requirements during HS. BCAA are oxidized for ATP synthesis in extrahepatic tissues and provide precursors for the biosynthesis of non-essential amino acids. They are also taken up by the mammary gland at a rate greater than what they are used in milk protein. Taken together, it was hypothesized that BCAA requirements may be increased during HS. BCAA entry rates into blood were assessed using a stable isotope approach and a 4-pool model. No differences were detected in daily entry rates or flux rates between pools indicating no change in requirements. When considering the results of all studies, reductions in milk yield are likely a result of altered macronutrient metabolism but further work is needed to confirm that hypothesis. Understanding the physiology behind HS related production losses is the first step in developing mitigation strategies. / Doctor of Philosophy / Heat stress (HS) is a global issue that compromises dairy cattle welfare and reduces milk production. On average the US dairy industry loses approximately $1.2 billion due to heat stress related production losses annually. With the global population expected to exceed 9 billion by 2050, strategies to mitigate HS related production losses are needed. Although cows exposed to HS conditions eat less food, that only explains about 50% of the production losses. It is hypothesized that the other 50% of milk yield losses is at least partially caused by increased gastrointestinal permeability (GIP), which elicits an immune response. Questions examined herein primarily focus on quantification of physiological and metabolic responses to HS. The objective of the first study was to identify a marker to assess GIP we could give orally to cows and detect in their urine. Commonly used GIP markers used in monogastric are carbohydrates, which have the potential to be fermented in the rumen. Sucralose was identified as a suitable marker due to its resistance to degradation in the rumen. The next study focused on measuring physiological responses of lactating dairy cows when exposed to HS conditions. Under the conditions of our experiment, HS decreased dry matter intake and milk yield without increasing GIP or inducing an immune response. It was determined that the reduction in dry matter intake was responsible for 66% of the reduced milk yield with the other 34% being associated with physiological changes other than increased GIP. The next study focused on how HS impacts the ability of skeletal muscle, mammary, and liver tissue to utilize glucose or palmitic acid as an energy substrate. The ability to switch between energy substrates is called metabolic flexibility. It was found that HS lowered the ability of skeletal muscle because it was unable to utilize fat as an energy source. Mammary and liver tissue exhibited no change in metabolic flexibility. The final study focused on how HS changed branched-chain amino acid (BCAA) plasma entry rates into plasma. An in vivo stable isotope method and a 4-pool mathematical model was used to predict how BCAA moved between pools which corresponds to the rate of protein turnover. Under the conditions of this experiment, no differences in BCAA entry rates were observed. Overall, results indicate altered energy substrate metabolism independent of immune activation stemming from altered GIP may be a driving factor in HS related production losses. Overall, this work contributes to understanding of HS biology and questions the established belief that increased GIP resulting in immune activation is responsible for about 50% of production losses.

No description available.

Recent experimental investigation on FSS arrays forming waveguides (FSGs) and horns showed that incident electromagnetic energy can be guided and radiated at specific frequencies. This thesis aims to provide the theoretical understanding of the waves propagating inside a cylindrical FSS waveguide. With immediate applications on horn antennas the research deals with cylindrical guides, made entirely from double periodic arrays. The theoretical analysis begins as a standard electromagnetic boundary value problem. The formulated system of algebraic equations is solved either for the complex propagation constant, by an iterative procedure or, for the fields. The analysis makes use of the Floquet modal expansion, the current representation as a set of sub-domain basis functions and the Method of Moments. Initially, the thesis is concerned with single periodic structures, which is a special case to the analysis. The efficiency of the model to provide stable and valid results is examined. Next the elements are finite dipoles. The effects of the dipole resonance to the propagating and radiating characteristics of the FSS is closely investigated. Other aspects include the effects of the periodicity and the element size. The investigation concludes with an FSG with square loop elements. Validation of the results for some designs is made by comparison with measured data.

This thesis improves on the design of the leaky-mode spatial light modulator, LMW-SLM, presented by Dr. Smalley[1]. Improvements include: input coupling gratings, a pulsed laser input, output coupling gratings, and a 3D printed adjustable module for the stabilization of critical alignments. First, input coupling gratings reduce the cost of the LMW-SLM from $500 to around $2, a drop in cost of over two orders of magnitude. This enables multiple modulators to be used in a single display and allows for an inexpensive modular design to be created. Second, a pulsed laser input allows for image creation without the use of a polygon for derotation. Removal of the polygon allows for direct viewing of the LMW-SLM output enabling near-eye and flat panel displays. Third, output coupling gratings allow for bottom exit devices that are essential for thin substrates and flat panel displays. Fourth, the 3D printed module allows for the critical alignments of the LMW-SLM to become permanent. This in turns allows for transportation of the created displays without a trained technician by abstracting away the complexities of the device. The resulting changes simplify hardware, reduce cost, and enable the LMW-SLM to be modularized and the resulting 3D displays to be transportable. These improvements are made possible by the addition of a one new mask step during fabrication, a simple circuit design, and a 3D printed module designed in SOLIDWORKS. Included in this thesis as attachments are the MATLab, Eagle, and SOLIDWORKS files used to create the improved LMW-SLM.

A network service provider typically sells service at a fixed traffic rate to customers. This rate is enforced by allowing or dropping packets that pass through, in a process called policing. Distributed policing is a version of the problem where a number of policers must limit their combined traffic allowance to the specified rate. The policers must coordinate their behaviour such that customers are fully allowed the rate they pay for, without receiving too much more, while maintaining some semblance of fairness between packets arriving at one policer versus another. A review of prior solutions shows that most use predictions or estimations to heuristically allocate rates, and thus cannot provide any error bounds or guarantees on the achieved rate under all scenarios. Other solutions may suffer from starvation or unfairness under certain traffic demand patterns. We present a new global ``leaky bucket'' approach that provably prevents starvation, guarantees full utilization, and provides a simple upper bound on the rate allowed under any incoming traffic pattern. We find that the algorithm guarantees a minimum 1/n share of the rate for each policer, and achieves close to max-min fairness in many, but not all cases. We also suggest some experimental modifications that could improve the fairness in practice.

A network service provider typically sells service at a fixed traffic rate to customers. This rate is enforced by allowing or dropping packets that pass through, in a process called policing. Distributed policing is a version of the problem where a number of policers must limit their combined traffic allowance to the specified rate. The policers must coordinate their behaviour such that customers are fully allowed the rate they pay for, without receiving too much more, while maintaining some semblance of fairness between packets arriving at one policer versus another. A review of prior solutions shows that most use predictions or estimations to heuristically allocate rates, and thus cannot provide any error bounds or guarantees on the achieved rate under all scenarios. Other solutions may suffer from starvation or unfairness under certain traffic demand patterns. We present a new global ``leaky bucket'' approach that provably prevents starvation, guarantees full utilization, and provides a simple upper bound on the rate allowed under any incoming traffic pattern. We find that the algorithm guarantees a minimum 1/n share of the rate for each policer, and achieves close to max-min fairness in many, but not all cases. We also suggest some experimental modifications that could improve the fairness in practice.