This thesis discusses a power electronics module (PEM) that is used to extract power from a human energy harvesting generator according to the user’s desired input power, and stores all of the extracted energy into an appropriately sized battery while staying within the charging limitations of the battery. The PEM can temporarily store the peak power produced by the generator allowing the reduction in the size of the battery required to the average power production level of the generator. The battery’s safety and longevity is maintained by charging them at the constant current and constant voltage rate. The design of the two-stage PEM, the requirements of the Energy Storage Capacitor (ESC) and battery size are discussed. The two controllers that control the PEM are explained and the different operating modes of the controllers are reviewed. A two-stage prototype digitally controlled average current mode control Boost converter and average current mode controlled Buck converter were designed and experimental waveforms were captured to test and validate the control theories used in the PEM. A Voltage Adaptive Gain compensator was used to optimize the closed loop response of both the Boost and Buck converters over their respective output and input voltage ranges. The DC efficiency of the prototype was measured with the peak efficiency of the Boost converter equal to 93% and the peak efficiency of the Buck converter measured at 93.7%. The total PEM system efficiency was measured at 87.9% at an input power level of 10 watts. The AC efficiency of the PEM was also measured with a peak efficiency of 91% with Vin = 15 V at Rin = 60 Ω. The software considerations for an embedded system, including power consumption and timing of real time events are reviewed. A software flow chart and timing diagram are provided to help visualize the sequence of the code. A design chart for selection of the size and voltage rating of the ESC was created. An experimental comparison of a single stage design without energy storage capability and the current PEM design was performed, with a power limited source, in order to show the effectiveness of the PEM and controllers at maximizing the power extraction from the generator. The PEM design was able to extract 50% more power than the single stage converter without energy storage capability. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2012-03-20 01:25:20.986

Abstract Background: Patients diagnosed with Type 1 diabetes mellitus (T1DM) require insulin therapy. Although necessary, insulin therapy is associated with an immediate increase in Body Mass Index (BMI). Excessive increase in BMI may lead to obesity, which is associated with both short and long-term negative health outcomes. The objective of this study was to determine whether weight change in the six months after diagnosis in children and adolescents with T1DM is related to obesity status at age 18. Methods: Data from the Diabetes Education Resource for Children and Adolescents database was used for this study. This unique database combines extensive clinical information on each patient with virtually universal coverage. The study population comprised all children 2-18 years old diagnosed with T1DM by DER-CA endocrinologists in Manitoba between 1997 and 2012 (N=377). BMI z- scores calculated from measured height and weight were used to classify BMI group membership using the 2000 Centers for Disease Control growth charts. Regression models were used to assess the association between change in BMI z-score six months after diagnosis, and BMI z-score at last visit prior to transfer to adult care. The models controlled for BMI z-score at diagnosis, sex, pubertal status and length of follow up. Additional stratified analyses examined sub-groups within the sample, to determine whether the effects were different for children with different characteristics (e.g. sex and pubertal status at diagnosis). Results: At diagnosis, 9% of the study cohort was underweight, 68% normal weight, 15% overweight and 8% obese. Most, (91%) but not all patients gained weight in the six months after T1DM diagnosis and initiation of insulin therapy. The pattern of weight change differed by BMI group at diagnosis, sex, and pubertal status. At last visit, average BMI z-scores for all groups of patients were above zero, and varied less than BMI z-scores at diagnosis. Results of the multivariate analytic model (adjusted R2= 0.56) show that BMI z-score at diagnosis was most important, followed by female sex, change in BMI z-score in the six months after diagnosis, the interaction between BMI z-score at diagnosis and change in BMI z-score in the six months after diagnosis, and duration of follow up. Conclusion: Results of this study demonstrate that patients’ BMI group, sex, and pubertal status at diagnosis influenced the pattern of their BMI z-score change in the six months after diagnosis, and thereafter. Diabetic care teams may need to monitor not only the amount of weight change in the period after T1DM diagnosis, but also consider BMI at diagnosis.

The purpose of this study was to determine the effect of diet, physical activity, and lifestyle characteristics on body weight of incoming freshmen at a Midwestern university. Research shows that many college students gain weight during their first year at college due to a change in dietary habits, lack of physical activity, and other lifestyle characteristics, such as drinking alcohol and smoking cigarettes.A systematic sample of incoming freshmen completed an online pre- and post-questionnaire regarding diet, physical activity, and lifestyle characteristics. In addition, students had their height and weight measurements taken to determine body mass index at the beginning and end of their first semester in college.Of the 69 incoming freshmen who participated in this study, 66.7% (n=46) gained an average of 2.6 ± 2.1 pounds and increased their BMI from 24.7 to 25.0 kg/m2 in one semester; 24.6% (n=17) lost an average of 1.5 ± 1.0 pounds. More than half of the students reported they usually tried to make healthy eating choices; however, 58% of the students reported having on average 2 meals per day and the majority did not meet the recommended number of servings for all five food groups. Less than 50% of the students exercised 3 or more days per week and less than one-third strength trained. The majority of incoming freshmen neither smoked nor consumed alcohol. Interestingly, there was an association of weight gain in college students who decreased the average number of meals they had each day or increased the average number of servings of fruits each week. / Department of Family and Consumer Sciences

Buildings energy consumption is rising continuously with massive urbanization progress, which then results in high greenhouse gas emission. A standing example is the urbanization process going on in the south-west part of China. Much has been discussed for improving building energy performance. However, to take another point of view, renewable energy source for buildings is a solution worth considering, for instance STES, which gains thermal energy from the sun, delivers it to buildings for space heating and hot tap water, also restores the solar energy in hot seasons in the storage system for the need of cold season.The aim of this paper is to couple the technology of STES with practical situation, explore the possibility of applying STES in south-west of China. This thesis work takes an estimation approach to weigh the possibility. The building project studied in this thesis is a campus project in the city of Guiyang, one of four major cities in the region of south-west China.Case study involves existing STES projects in Munich Germany and Anneberg Sweden, the performance evaluation of the Anneberg project is later to serve as an example in system gain & losses proportion, to guide the estimation work of the campus project.The estimation conclusion is drawn based on a cross-sectional analysis method, take the technology of STES, the practiced STES project and building projects in China as three loops visually, and observe how much they overlap each other. Behind the visual illustration, the overlapping is assessed with several factors, for instance possibility of storage system at location, possible STES performance and solar irradiation condition at site location etc. If most of these factors are checked to be “Ok” or “Good”, then the overlapping area is considered “large” enough, and therefore suggests a decent chance to implement STES system in the south-west China.A solar gain and sunlight simulation from a new police station energy consumption report assists in calculating the possible solar gain for the campus project, as the very close distance between these two sites (30 km) promises them the very similar solar irradiation condition. While the energy consumption of the studied campus project offers the energy demand for space heating and hot tap water in the need of 19,000 students, which is to be evaluated as the task of the STES system in the estimation work. Both building project reports are filed by GARDI (Architecture design research institution of Guizhou).Some key factors have been calculated and estimated, the heat demand of the studied campus project in Guiyang is 5,558 MWh/year, and the possible solar gain of this campus complexity is 4,900 MWh/year based on the gain & losses proportion of the Anneberg project evaluation. Due to the very different climate condition of Guiyang and Anneberg, as well as other uncertain factors such as effective roof area, solar collector efficiency, a sensitivity analysis evaluated the result with different parameters in changes of percentage. Final results in the changes of effective roof area at 80% and 85 %, borehole losses at 50% and 45%, available solar gain at 38%, STES system is shown to be capable of providing sufficient heat to buildings. If the heating demand and hot tap water, in the case of the campus project alone are all covered by STES system, there will be a reduction in CO2 emission of 5,368 tons/year.Cross-sectional analysis concludes four out of eight factors checked as “Good” and two as “Ok”, other two as “Unsure”. Other three cities (Chengdu, Kunming, and Chongqing) are brought to comparison later regarding climate condition. Besides Guiyang, two out of three are evaluated to have potential of STES implementation according to their sun hours, annual average temperature etc. STES system is estimated to be possible for implementation in south-west of China as the conclusion.

As CMOS technologies advance to 22-nm dimensions and below, constructing analog circuits are difficult to design within permitted specifications. One of the reasons for this is a limit of voltage resolution. In this situation, time-mode processing is a technique that is believed to be well suited for solving many of these challenges. A primary advantage of this technique is the ability to achieve analog functions using digital logic structures. Time difference amplifiers (TDA) can be a key component to realize fine time solutions. TDA are an innovative method to improve the time resolution as well as the evolution of ADC. This thesis introduces a TDA that amplifies the input time difference between two signals by a fractional gain. The closed loop gain control system used in this work consists of a pseudo differential current starved delay element (PDCSDE) and a monotonic digitally controlled delay element (DCDE). By using these elements to create a delay chain and a control loop, the result is a stable fractional time difference gain (TD gain). The system was designed and simulated in 65nm process at 1.2V power supply. The measured results show that this TDA achieves a fractional TD gain offset lower than 1.3%, with supply variation of ±15%, and input range as wide as ±250ps. The new design was also more resilient to process, voltage and temperature (PVT) variations

With increased demand for bandwidth-hungry applications such as video-on-demand, wavelength-division-multiplexing passive optical network (WDM-PON) has become a strong contender in overcoming the last mile bottle neck. However, the wide-scale deployment of WDM-PONs has been delayed mainly due to the high cost of wavelength-specific optical components. To realize cost-effective WDM-PONs, various wavelength-independent, so called colorless architectures, have been developed so that all the subscribers can have identical optical network units (ONUs). In such WDM-PONs, however, single-fiber bidirectional transmission results in degradation of system performance caused by interference between the signals and backreflections. This thesis investigates the impact of backreflections on single-fiber bidirectional WDM-PONs. A WDM-PON with various optical line terminals (OLTs) and colorless ONU configurations is presented. The dependence of the power penalty, caused by backreflections, on a variety of parameters is investigated. This includes parameters such as the source linewidths, receiver bandwidth, transmission line loss (TLL), ONU gain, chirp effect at the ONU and optical return loss (ORL), in various WDM-PON configurations. The WDM-PON with continuous wave (CW) seed light and remodulation schemes are both presented and studied experimentally. The impacts of the backreflections on the single-fiber bidirectional WDM-PON with various OLT and ONU configurations are compared and analyzed accordingly.

No description available.

One mechanism by which spatial attention affects visual perception is through the alteration of the signal-to-noise ratio for a particular stimulus. This is known as sensory gain control. Sensory gain effects can be measured electrophysiologically through changes in the amplitude of the P1 event related potential (ERP) component. Manipulating perceptual load by increasing or decreasing task difficulty can influence spatial attention and can therefore modulate the P1 component. Sensory gain effects are well characterized with peripheral attention, but have rarely been studied at fixation. The few studies that have been conducted that look at sensory gain for foveal stimuli have yielded conflicting results, and sensory gain with centrally presented extrafoveal stimuli has only been found in emotion studies. The present study manipulated attention allocation towards foveal and extrafoveal stimuli at fixation, using two levels of perceptual load for each stimulus size. ERPs were recorded in response to stimulus onset, and tested for differences in P1 and N1 amplitude across perceptual load conditions. Sensory gain effects, as indexed by an increase in P1 amplitude with an increase in perceptual load, were predicted for extrafoveal but not foveal stimuli. Changes in P1 amplitude were not found for either type of stimuli, suggesting that sensory gain effects either may not be present at fixation or are not susceptible to manipulation by perceptual load. The N1 component was expected to increase in amplitude for high-load stimuli, due to the N1 attention effect. However, the opposite result was found, suggesting that there is an additional effect of perceptual load on early visual processing, distinct from sensory gain control.

Weight gain affects all living beings and excessive weight gain can lead to obesity and comorbidities linked to obesity. In order to better understand how the college student population gains weight and increase in BMI, data collected under the Council of Environment and Dietary Activity (CEDA) at Texas A&M University was examined and analyzed in order to understand how physical activity, sedentary behavior, and dietary activity affect weight gain or weight loss. The college population was divided into BMI categories, gender, and where they lived on campus at Texas A&M University. The data shows that physical activity was associated with loss of weight and BMI in females. Sedentary behavior was associated with weight gain in males but also weight loss in females. Meat consumption was associated with weight gain in males. Fish consumption was associated with weight loss in females. Pastries consumption was associated with weight gain in females. Physical activity appeared to have a stronger effect on weight than dietary behavior even though both can interact to affect weight for females. Speed of service and location have a significant effect on where students would eat. In conclusion, physical activity and sedentary activity have an effect on weight and BMI. Diet can also have an effect on weight and BMI. More specifically, sugar snacks affect weight in females and meat affects weight and BMI in males. However, physical activity appears to have a larger on weight and BMI than diet. Location also affects where a student will eat.

This thesis details the design and construction of an experiment to measure the radial distribution of laser gain in a cylindrical Helium-Neon laser gain tube. This distribution is important as it can effect the transverse mode structure of a running ring laser. Earlier theoretical models of the distribution were not supported by high quality experimental data and fail to take into account some physical processes. A resolution of 8 parts per million in gain and 50 μm in radial position has been achieved. Gain distributions have been measured and are shown to be well modeled by a 0th order Bessel function with first roots at the tube walls and a central dip depending on excitation power; except for the region very near to the tube walls where a very rapid increase in gain has been observed. Hydrogen has been identified by spectroscopic analysis as the primary constituent of gas contamination and cause of the long term reduction in gain of large ring lasers. Additional work has been done to detect a proposed non-classical Lense-Thirring field around a spinning lead superconductor. It was found that any effect is at least 20 times smaller than predicted. Techniques and tools for data acquisition programming have been reviewed focusing on difficulties with coupling of user interface and application logic, monolithicity, difficulties with scripting and algorithm implementation.