The conventional power factor correction circuit has a fixed output voltage. However, in some applications, a PFC circuit with a wide output voltage range is needed. A single phase power factor correction circuit with wide output voltage range is developed in this work. After a comparison of two main power stage candidates (Buck+Boost and Sepic) in terms of efficiency, complexity, cost and device rating, the buck+boost converter is employed as the variable output PFC power stage. From the loss analysis, this topology has a high efficiency from light load to heavy load. The control system of the variable output PFC circuit is analyzed and designed. Charge average current sensing scheme has been adopted to sense the input current. The problem of high input harmonic currents at low output voltage is discussed. It is found that the current loop gain and cross over frequency will change greatly when the output voltage changes. To solve this problem, an automatic gain control scheme is proposed and a detailed circuit is designed and added to the current loop. A modified input current sensing scheme is presented to overcome the problem of an insufficient phase margin of the PFC circuit near the maximum output voltage. The charge average current sensing circuit will be bypassed automatically by a logical circuit when the output voltage is higher than the peak line voltage. Instead, a resistor is used to sense the input current at that condition. Therefore, the phase delay caused by the charge average current sensing circuit is avoided. The design and analysis are based on a novel air conditioner motor system application. Some detailed design issues are discussed. The experimental results show that the variable output PFC circuit has good performance in the wide output voltage range, under both the Boost mode when the output voltage is high and the Buck+Boost mode when the output voltage is low. / Master of Science

A marker model of fecal kinetics using chromic oxide (Cr) or ytterbium chloride (Yb) is being developed for grazing horses. The model consists of removal of feces at a constant rate from a single compartment, the prefecal mass. It was tested in experiments on stall-fed horses in the context of digestion balance trials. Following the preliminary work of Holland et al., (1998), three improvements in experimental design were tested. First, the rate constants were determined from both the administration and post-administration curve of the one-compartment model. Second, markers were administered three times a day to reduce diurnal variation in fecal marker concentration. Third, yttrium (Y) and Yb were tested were tested as internal markers, for the estimation of digestibility of hay and supplements, respectively. Eight horses were fed Diet 1 (orchardgrass/alfalfa mixed, OG) or Diet 2 (tall fescue/alfalfa mixed, TF) in Exp.1, and Diet 3 (OG plus fat-and-fiber supplement, OGFF) or Diet 4 (OG plus sugar-and-starch supplement, OGSS) in Exp.2. Balance-marker experiments were conducted for 17 and 20 d, with 7 and 10 d of dietary accommodation in Exp.1 and 2, respectively. Chromic oxide and Yb were administered orally and fecal samples were collected every 8 h for 8 d. Dry matter, Cr, Yb and Y were measured in feeds and feces. In balance experiments, estimates of DMD (D_E) using Y, were determined precisely (SE 1 to 3 %) for hay and hay and supplement diets. Linear relationships, correlations and calibration curves were determined, validating Y as a marker. Mean daily fecal Cr data (C_t) at time t (days) including a delay (d) were fitted to a single exponential, with one rate constant (k), rising to an asymptote (C_a): C_t = C_a - C_a·e^-k(t-d) Diets 1 and 2 had two sets of C_tdata, total collection (a) and fecal grab data (b), and each set was used in model development. Diets 3 and 4 had two sets of C_t data (both using fecal grab data), Cr marker dilution (3Cr and 4Cr) and Yb marker dilution (3Yb and 4Yb). For pooled data, delays of 3 to 6 h (Diets 1a, 1b, 2a and 2b) and delays of 5 to 7 h (Diets 3Cr, 4Cr, 3Yb and 4Yb) gave best fits (highest estimates of R²). The delays introduced to the Cr model for both 3Cr and 4Cr diets did not correspond to the preliminary study (Holland et al., 1998), where a 2 h delay gave the best fit in the model for horses fed hay and supplement. The present estimates may more realistically relate to mouth-to-cecum transport times, because the marker was administered three times a day instead of once, and the initial part of the tracer curve was more precisely defined. The results showed that fecal Cr kinetics could be calibrated precisely (SE 1 to 3 %) to predict fecal DM output of horses fed Diets 1b, 2b, 3a but not 4a. Similarly, fecal Yb kinetics could be calibrated to predict fecal DM output of horses fed Diet 3b but not 4b. The rate constants yielded turnover times (TT) that were longer with hay and supplement diets, than with hay alone, and which contrast with previous findings in the horse. However, the longer TT were similar to slower rates of marker excretion in sheep fed concentrates instead of all-roughage diets, suggesting that the lower fiber content retarded the rate of propulsion of digesta through the digestive tract. For two of the eight models of fecal kinetics, the rate constants of the post-administration curve were not well determined by the data, and rate constants from the administration curve were used. In future experiments, more frequent fecal sample collection during the post-administration period may improve rate constant determination. Improvements in diurnal variation of fecal marker concentration were obtained by dosing three times a day. But discrepancies between Cr and Yb concentration means of diurnal samples and combined samples showed incomplete mixing, the major source of tracer error. Therefore more frequent marker administration and fecal samples should be tested in future experiments to achieve more thorough mixing in the prefecal mass for modeling fecal kinetics, and in the small intestine for estimating digestibility. / Master of Science

This thesis examines the economic impact of two alternative canning plant sizes in Scott County, Virginia. The impacts of a community cannery as well as a commercial cannery are analyzed with respect to changes in output, employment, and income. Several uses for the commercial cannery are considered, such as specialization in different product categories. In both cases, an input-output model is used to evaluate the effects of the operation of the cannery in the county. The results indicate that the impact of the commercial cannery is significantly larger than the community cannery. Specialization of the commercial cannery in the Canned Specialties sector has the largest impact with respect to industry output and labor income while specialization in the Sausages and Other Prepared Meats sector has the largest impact with respect to employment. / Master of Science

Advances in technology have now made it possible to analyze cardiac output (Q) with only a single-breath, making measurements during exercise quicker and less invasive for the subject. Certain non-invasive techniques allow for measurement of the disappearance of a soluble inert gas as it diffuses across the blood-gas barrier in the lungs. The rate of disappearance of the gas is directly proportional to the flow of blood past the lungs and subsequently provides an estimate of pulmonary capillary blood flow (Qc), or Q. The SensorMedics® Corporation (Yorba Linda, CA) has developed a single-breath acetylene (C₂H₂) technique (SensorMedics Vmax 229TM), which includes a simple device to linearize expiratory flow rate by increasing the time by which the sensors can measure the disappearance of the marker gas and improve quantification. The purpose of this investigation was to determine the reproducibility of the C₂H₂ single-breath technique during ramping exercise testing with the addition of a starling resistor in 11 apparently healthy, sedentary volunteers (7 male and 4 female). Subjects performed three maximal ramping exercise test sessions over a 6-week period and Qc was measured at rest and at three time points during the exercise test. The C₂H₂ single-breath Qc measurement technique was shown to be repeatable when systematically related to VO₂ (Qc/VO₂ relation highly correlated r² = 0.72-.74), but slightly lower than previously reported. Means and 95% confidence intervals revealed the precision of the technique over repeated testing days. This method was able to capture Qc measurements at intensities greater than 75% VO₂pk in all subjects with the use of the Starling resistor. Bland-Altman plots reveal Qc measures to be about 50% more variable than highly reproducible measures such as VO₂ and HR. Intraclass reliability coefficients (r) found through repeated measures ANOVA were found to perform low (rx,x= -0.11-0.31) from rest throughout all intensities of exercise. This device is limited in the ability of the sensors to accurately analyze Qc with subjects who are unfamiliar and have difficulty with the single-breath maneuver. Such instances make it difficult for objective, accurate determinations to be made by the clinician. The C₂H₂ single-breath method was found to capture Qc at higher intensities and a high level of precision with the addition of the starling resistor. However, more evidence needs to be analyzed before use of this device can be put into clinical practice. / Master of Science

The L2 gain of a nonlinear time-dependent system measures the maximal gain in the transfer of energy from admissible input signals to the output signals, in which both the input and output signals are measured with the L2 norm. For general nonlinear systems, obtaining a sharp estimate of the L2 gain is challenging both theoretically and numerically. In this thesis, we explore a computationally efficient way to obtain numerical estimations of L2 gains for systems with quadratic nonlinearity. The approach utilizes a recently developed method that solves a class of Hamilton-Jacobi-Bellman equations via a Taylor series-based approximation, which is scalable to high-dimensional problems given the utilization of linear tensor systems. The ideas are demonstrated through a few concrete examples that include a one-dimensional problem with an explicit energy function and several Galerkin approximations of the viscous Burgers equation. / Master of Science / With nonlinear systems that are of the form of input-output models, questions often arise as to how to measure the energy that passes through such systems and determine strategies to look for specific signals that allow the designer freedom to explore certain system behaviors. The energy comes in the form of a signal. For general nonlinear systems, obtaining a sharp estimate of such energy gain is challenging both theoretically and numerically. In this thesis, we explore a computationally efficient way to obtain numerical estimations of these gains for systems with quadratic nonlinearity. The approach combines fundamental theoretical understandings established in the literature with scalable software recently developed in approximating the solution of the underlying partial differential equation, called the Hamilton-Jacobi-Bellman (HJB) equation. In this approach, the energy gain is linked to a single scalar parameter in the HJB equation. Roughly speaking, the energy gain is the lower bound of this scalar parameter above which the HJB equation always admits a non-negative solution. Thus, it boils down to approximating the HJB solution using the software while changing this scalar parameter. We will present the theoretical foundation of the approach and illustrate the foundation through several academic examples ranging from low to relatively high dimensions.

An investigation of the pattern of structural change in a static input-output system is considered, when a series of operational optimizations are performed in one or more subsystems. Specifically, changes in the relative price of each commodity in an economy, along with their implications for the quantities associated, are analyzed. By operationally optimizing a sector, a production process is selected in such a way that the input requirements from other sectors in the economy do not exceed the current equilibrium level as specified by the input-output economy. When the new optimal process is substituted for the current equilibrium process, the input-output structure may be perturbed and a new equilibrium solution needs to be sought. For the multi-sectoral problems, the system would be considered stable if the necessity for the further perturbation ceases, while an equilibrium solution exists to the current input-output system. Three different price models are developed in trying to obtain a new stable system. Depending upon three distinct sets of economic reasons behind, these models are named as the acquisition, the consolidation, and the appreciation model. This study concludes that under all the normal circumstances, a static input-output system does reach a stable state, if the sectoral optimization is conducted through linear programming. This study also investigates the effects of operational optimization of sectors on the quantity side of the economy. / Master of Science

Hypotension is a common finding in hospitalized, critically ill neonatal foals. Hypotension may be a function of low cardiac output or increased cardiac output and decreased systemic vascular resistance. In the first instance, treatment would include fluids and/or inotropes and in the second, fluids and/or vasopressors. Therefore, cardiac output measurements are expected to help guide the treatment of hypotension associated with critical illness and/or anesthesia in neonatal foals. However, a practical and safe method of measuring cardiac output has not been described for the foal. Lithium dilution, a new method of cardiac output determination not requiring cardiac catheterization, has recently been reported in adult horses. We compared this method to thermodilution in isoflurane anesthetized, 30 to 42 hour old foals and found good agreement (mean bias 0.0474L/min; limits of agreement -3.03 to 3.12) between the two methods in a range of cardiac outputs from 5.4 to 20.4 liters/min. The lithium dilution technique is a practical and reliable method of measuring cardiac output in anesthetized neonatal foals, and warrants investigation in critically ill conscious foals. / Master of Science

The submitted diploma thesis is dedicated to the calculation of the estimation of output gap by three estimating techniques (Hodrick-Prescott filter, Kalman filtering, and Cobb-Douglas production function) for the Czech Republic during the years 1995-2009, and, consequently, to their usefulness for testing the Okun's law as a suitable predicative tool. In other words, which of the mentioned methods is the most appropriate one for an accurate prediction of the rate of unemployment. To achieve this, the Box-Jenkins methodology is used for modelling and designing the cyclical unemployment forecasts and dynamic version of the Okun's law. The results indicate that, for the given period, there is relatively strong and unstable relationship between changes in output gap and changes in cyclical unemployment in the Czech Republic. The most suitable technique for the estimating of the future development of unemployment gap seems to be the Cobb-Douglas production function approach. This is namely based on the quantity of gained forecast errors and Granger causality.

The main target of the thesis is analysing of short-term indirect cross-sectoral impacts of taxation of electricity, solid fuels and natural gas on particular sectors of NACE in the Czech Republic, especially impacts on production prices. The key instrument for the analysis is the short-term price model for the Czech Republic, created as a component of the thesis. A secondary target is focused on the analysis of direct impacts, especially impacts on prices and expenditures of particular sectors of NACE. Within the scope of the main target, there are five different variants of taxation. For each of them the impact of taxation of particular commodities on changes in production prices of particular sectors of NACE is simulated. Than two different variants, both of them including taxation of all commodities, are compared. The thesis includes also two hypotheses, which are going to be confirmed or disproved on the basis of obtained results. For achieving the main target the methodology of Leontief input -- output analysis was chosen (Leontief, 1966). This is the key instrument for creating short-term price model for the Czech Republic. This method is suitable especially for analysing short-term cross-sectoral impacts, however under necessary condition of no changes in current technologies, agreements and cross-sectoral relations. This condition represents strict limitation for the price model created for the thesis. Regarding scientific contribution, the main asset of this thesis is creation of macroeconomic short-term price model for the Czech Republic, which is based on methodology of Leontief input -- output analysis. The additional contribution is calculation of the short-term impacts of new environmental taxation on production prices of particular sectors of NACE. Considering available information, environmental taxes in the Czech Republic have not been analysed by Leontief input - output methodology yet. There is not also sufficient analysis of environmental taxes impacts on particular sectors of NACE in the Czech Republic. The thesis is divided to seven chapters. The first chapter focuses on introduction to environmental tax regulation issue. The second chapter presents theories and concepts of taxation impact analysis. The third chapter focuses on models and empirical research in environmental taxation area. The fourth chapter is dealing with basic practical aspects of introduction of new energy taxation in the Czech republic and presents data useful for the following analysis. The fifth chapter consists of describing of applied methodology and describing of creation of the price model. The sixth chapter summarises results of simulation of direct impact of taxation on average prices for companies and on expenditures of particular sectors of NACE. The seventh chapter presents results of cross-sectoral analysis of indirect macroeconomic impacts for all variants; the chapter includes also testing of hypotheses and comments of final results.

Estudo sobre a aplicabilidade de construção de mapas conceituais, a partir de relatórios descritivos de patentes, com o objetivo de se identificar conhecimento científico utilizado na geração de inovações. Parte do pressuposto que o uso de mapas conceituais permite estabelecer relações entre a produção científica e a produção de patentes, complementando critérios bibliométricos de avaliação da produção científica. Trata-se de estudo exploratório, baseado em referencial teórico sobre o desenvolvimento de mapas conceituais, seu uso e apropriação pelas diversas áreas do conhecimento, complementado por testes de aplicação dos conceitos na construção de mapas conceituais em amostra de patentes acadêmicas brasileiras. O uso de mapas conceituais se mostrou eficiente para explicitar o assunto e suas facetas, mas não para se identificar o conhecimento básico utilizado na sua concepção. / Study on the applicability of construction of conceptual maps, from descriptive reports of patents, in order to identify scientific knowledge used in the generation of innovations. The study starts from the premisse that the use of conceptual maps allows to establish relationships between the scientific output and the production of patents, complementing bibliometrical criteria of appraisal of the scientific production. It is an exploratory study, based on theoretic references about the development of conceptual maps, its use, and appropriation by the various knowledge areas, complemented by enforcement tests of the concepts in the construction of conceptual maps in sample of Brazilian academic patents. The use of conceptual maps appeared efficient in order to explicite the matter and your facets, but not to identify the basic knowledge used in its conception.