This thesis intends to examine the principles of operation for switched reluctance machines (SRM) and examine the power electronic drive circuits that control them, in order provide a basis of understanding for evaluating total drive efficiency and responsiveness potential. This document specifically examines the characteristics of a motor drive circuit which affect motor and converter efficiency and driving performance. A drive topology suited for efficient operation and excellent responsiveness is proposed. Finally, a SRM drive system model for evaluating these systems in simulation is described as a tool for comparative evaluations in future work. The end goal of this work is to provide a foundation of knowledge for future work, developing in-wheel, SRM-based, high performance hybrid electric drivetrains in future ground combat vehicles which are modular, possess an open architecture for upgrades, and operate with high efficiency and improved mobility. / text

Historically, cultural pressures to be thin and their effects on women (e.g., body dissatisfaction, disordered eating) have received considerable attention from researchers and clinicians. However, acknowledgement of cultural pressures on men to be muscular and lean is much more recent, as are men's increasing rates of body dissatisfaction and body-changing behaviors (i.e., drive for muscularity, nutritional supplement/steroid use, excessive weightlifting). The increasing presence of idealized lean, muscular men in the media may be one of the influences on men's increasing body dissatisfaction, although studies examining the relationship between viewing these idealized portrayals and men's drive for muscularity/body satisfaction have yielded mixed results. Additionally, individual difference factors that may influence this relationship need further investigation. The purpose of this study was to address these two areas of research. It was hypothesized that men exposed to idealized television portrayals of lean, muscular men would report higher muscle/body fat dissatisfaction and drive for muscularity attitudes scores compared to men exposed to television portrayals of average-looking men. Additionally, it was predicted that men who report higher perfectionism, neuroticism, and drive for muscularity, and who more strongly endorse traditional attitudes about the male role, would report higher drive for muscularity and muscle/body fat dissatisfaction at post-test compared to men who report lower perfectionism, neuroticism, and drive for muscularity, and who are less concerned with traditional male role norms. Two-hundred-thirty-five undergraduate men at The University of Texas at Austin participated in the online study. During Phase 1, participants completed questionnaires assessing drive for muscularity, muscle/body fat dissatisfaction, perfectionism, neuroticism, and attitudes about the male role. One week later, they were randomly assigned to either the muscular-image or average-image group to complete Phase 2. After viewing television commercials corresponding with their experimental groups, participants again completed all pre-test measures. Results suggested that men in the average-image group (rather than the muscular-image group) with high drive for muscularity experienced greater body fat dissatisfaction than men with low drive for muscularity. Interesting findings regarding the relationships among perfectionism, neuroticism and drive for muscularity/body dissatisfaction also emerged. Implications of the study, strengths, limitations and suggestions for future research are discussed. / text

The neotropical lizard genus Anolis is an important model system for studies of the ecology and evolution of animal diversity. One of the most striking elements of Anolis diversity is found in the morphology of the dewlap, an extensible flap of colored skin on the throat that anoles use to communicate during social interactions. The evolutionary forces that have promoted the evolution of dewlap diversity are poorly understood. A study of reproductive success in A. carolinensis showed for the first time that dewlap color is currently under selection in an anole (Chapter 1). However, this is unlikely to be a result of intrasexual competition because neither dewlap morphology nor reproductive success are related to male territory size or quality. Instead the dewlap may be under intersexual selection from female mate choice. In addition to sexual selection, the dewlap may evolve in response to a variety of other processes such as species recognition, predation, sensory drive, or a combination of these. A study of variation among populations of a single species, A. sagrei, revealed that the dewlap may be undergoing rapid adaptive diversification driven by several of these processes simultaneously (Chapter 2), while a study of variation among species in dewlap size showed that similar processes are likely shaping the evolution of the dewlap in female anoles (Chapter 3). In a case study of male-female pair formation in the Costa Rican anole A. limifrons, dewlap size or color were not good predictors of which males would form pairs and which would not, though males and females that were similar in size were found to form pairs more often than animals that were dissimilar in size (Chapter 4). Finally, a study of the correlated evolution of traits related to locomotion in anoles found that morphology, behavior, and habitat use evolve in tandem among 31 species of anoles from the Greater Antilles (Chapter 5). Together, these studies suggest that the evolutionary ecology of anoles is more complex than previously thought, and that future studies of the dewlap may provide more general insight into the evolution of diversity of animal ornaments.

The area of study is the Avery Drive drainage area. The objective of these projects is to alleviate frequent flooding at the Avery Drive neighborhoods. RC&A designed two options for improving the Avery Drive drainage area. Option one increases the capacity of the existing sewer system, and option two constructs a new storm drain system along Simon Street while keeping the existing system in place. Although both options offer preliminary solutions for alleviating flooding, the designs are unviable due to the lack of data that was available for the study. The following research will prove that RC&A fulfilled its contractual obligation of practicing due diligence by recommending further investigation to obtain valuable data for a complete and successful final design, rather than providing a solid recommendation based on existing data. / text

Η παρούσα διπλωματική εργασία πραγματεύεται το σχεδιασμό και την κατασκευή διάταξης φόρτισης ενός ηλεκτροκινητήριου συστήματος. Η εργασία αυτή εκπονήθηκε στο Εργαστήριο Ηλεκτρομηχανικής Μετατροπής Ενέργειας του Τμήματος Ηλεκτρολόγων Μηχανικών και Τεχνολογίας Υπολογιστών της Πολυτεχνικής Σχολής του Πανεπιστημίου Πατρών. Στα πλαίσια του θεσμού της πρακτικής άσκησης του τμήματος, ένα τμήμα της εργασίας αυτής εκπονήθηκε στο τεχνικό γραφείο ΛΙΑΣΚΟΣ Ο.Ε. Σκοπός είναι η κατασκευή ενός μετατροπέα πλήρους γέφυρας, που θα ελέγχει κατάλληλα μια μηχανή ξένης διέγερσης, η οποία συνδέεται μέσω ενός συστήματος μετάδοσης μ’ έναν κινητήρα με τελικό σκοπό την φόρτιση του κινητήρα με επιθυμητές ροπές για μελέτη της λειτουργικής συμπεριφοράς του. Αρχικά αναλύθηκε ένα ηλεκτροκινητήριο σύστημα και μελετήσαμε τα επιμέρους τμήματα που το αποτελούν. Παρουσιάζονται διάφορα είδη φορτίων με τις αντίστοιχες χαρακτηριστικές ροπής-στροφών καθώς και εφαρμογές που χρησιμοποιούνται. Επίσης αναλύθηκε συνοπτικά η μηχανή συνεχούς ρεύματος. Στη συνέχεια αναλύθηκε ο μετατροπέας πλήρους γέφυρας, οι τρόποι λειτουργίας του, με τους οποίους μπορεί να ελέγξει τη μηχανή συνεχούς ρεύματος ώστε να λειτουργεί στα τέσσερα τεταρτημόρια, ενώ ιδιαίτερη προσοχή δόθηκε στην ανάλυση των μεθόδων κατάλληλης παλμοδότησης των διακοπτικών στοιχείων. Στο επόμενο βήμα πραγματοποιήθηκε η προσομοίωση τόσο των επιμέρους συστημάτων όσο και του ολικού συστήματος, με σκοπό να εξακριβωθεί η ορθή λειτουργία του πριν την κατασκευή. Οι προσομοιώσεις πραγματοποιήθηκαν με την βοήθεια του λογισμικού Simulink του Matlab . Τέλος κατασκευάζεται η πειραματική διάταξη για να ληφθούν τα πειραματικά αποτελέσματα και να συγκριθούν με τα θεωρητικά, ώστε να εντοπιστούν και να δικαιολογηθούν τυχόν διαφορές μεταξύ της θεωρητικής ανάλυσης και των μετρήσεων στην πραγματική διάταξη, καθώς και για να εκτιμηθεί η απόδοση του συστήματος. / This thesis deals with the design and construction of a torque simulator device for an electrcic drive system. The thesis was conducted in the Laboratory of Electromechanical Energy Conversion, Department of Electrical and Computer Engineering of the University of Patras. The aim is to build a full-bridge converter, which will properly control a separately fed dc-machine, which is connected via a transmission system with a motor. The final goal is to load the engine with the desirable torque, in order to study it’s functional behavior. Initially we analyzed an electric drive system and studied the individual parts that make it up. We presented various kinds of loads with their corresponding torque-speed characteristic and applications in which they are used. We also analyzed, succinctly, the functional behavior of a DC machine. Then we analyzed the full-bridge inverter and it’s modes of operation, through which the DC machine can be controlled and operate in all four quadrants. Afterwards, methods for the proper pulse-control strategy of switching elements were studied. The next step was the simulation of both, subsystems as long as the overall system, in order to check the proper operation before construction. The simulations were performed using the software Simulink of Matlab. Finally the experimental setup was constructed, in order to obtain the experimental results and to compare them with the theoretical, to identify and justify any differences between the theoretical analysis and measurements on the real device, and to evaluate the system performance.

Variable speed drive technology has advanced dramatically in the last 10 years with the advent of new power devices. In this study, a three phase induction motor drive using Insulated Gate Bipolar Transistors (IGBT) at the inverter power stage is introduced to implement speed and position control for the revolving stage in the Frederic Wood Theatre This thesis presents a solution to control a 3-phase induction motor using the Texas Instruments (TI) Digital Signal Processor (DSP) TMS320F2407A. The use of this DSP yields enhanced operations, fewer system components, lower system cost and increased efficiency. The control algorithm is based on the constant volts-per-hertz principle because the exact speed control is not needed. Reflective object sensors which are mounted on concrete frame are used to detect accurate edge position of revolving stage. The sinusoidal voltage waveforms are generated by the DSP using the space vector modulation technique. In order to satisfy some operating conditions for safe and agreeable operation, a look-up table, which is used to give command voltage and speed signals in software, is applied to limit the maximum speed and acceleration of the revolving stage. Meanwhile, a boost voltage signal is added at the low frequency areas to make the motor produce maximum output torque when starting. A test prototype is then built to validate the performance. Several tests are implemented into the IGBT drive to explore the reason for unacceptable oscillations in IGBT’s gate control signals. Improvement methods in hardware layout are suggested for the final design.

Improved transient performance and converter miniaturization are the major driving factors behind high frequency operation of switching power supplies. However, high speed operation is limited by topology, control, semiconductor, and packaging technologies. The inherent mitigation of switching loss in resonant converters makes them prime candidates for use when the limits of switching frequency are pushed. The goal of this thesis is to address two areas that practically limit the achievable switching frequency of resonant topologies. Traditional control methods based on single cycle response are impractical at high frequency; forcing the use of pulse density modulation (PDM) techniques. However, existing pulse density modulation strategies for resonant converters in dc/dc applications suffer from: • High semiconductor current stress. • Slow response and large filter size determined by the low modulating frequency. • Possibly operating at fractions of resonant cycles leading to switching loss; thereby limiting the modulating frequency. A series resonant converter with variable frequency PDM (VF-PDM) with integral resonant cycle control is presented to overcome the limitations of existing PDM techniques to enable efficient operation with high switching frequency and modulating frequency. The operation of the circuit is presented and analyzed, with a design procedure given to achieve fast transient performance, small filter size, and high efficiency across the load range with current stress comparable to conventional control techniques. It is shown that digital implementation of the controller can achieve favourable results with a clock frequency four times greater than the switching frequency. Driving the synchronous rectifiers is a considerable challenge in high current applications operating at high switching frequency. Resonant gate drivers with continuous inductor current experience excessive conduction loss, while discontinuous current drivers are subject to slow transitions and high peak current. Current source drivers suffer from high component count and increased conduction loss when applied to complementary switches. A dual-channel current source driver is presented as a means of driving two complementary switches. A single coupled inductor with discontinuous current facilitates low conduction loss by transferring charge between the MOSFET gates to reduce the number of semiconductors in the current path, and reducing the number of conduction intervals. The operation of the circuit is analyzed, and a design procedure based on minimization of the total synchronous rectifier loss is presented. Implementation of the digital logic to control the driver is discussed. Experimental results at megahertz operating frequencies are presented for both areas addressed to verify the theoretical results. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2012-09-09 20:43:56.997

In healthy organisations, employee well-being is coexistent with efficient and effective work organisations. Improving employee wellbeing is therefore of significant importance for organisational performance. This study draws on the Job Demands-Resources model which suggests that the balance between job demands and resources impacts on individual well-being. Using an on-line survey (N=162) this study investigated the direct and indirect relationships between job demands, engagement and drive on work-life conflict and well-being. In general, the findings of this study are consistent with the JD-R model; job demands predicted work-life conflict, while the strongest predictor of well-being was the job resource of work engagement. Further, once indirect relationships were considered, it was found that engagement, a construct generally associated with positive outcomes, and overtime hours lead to psychological detachment issues for employees; consequently contributing to their work-life conflict. In addition, work-life conflict was found to mediate the relationships between the job demands of external work pressures and drive and wellbeing, suggesting that being pressured to put one’s work before their other interests and having an excessive work-drive contribute to reduced employee well-being. The unique contribution of this study lies in the assertion that while engagement has positive influence on employee and organisational outcomes, it is important that organisations and individuals ensure that work does not cause a negative spillover into employees’ private life, enabling them to recover after work and be ready for the next day’s challenges. The findings are discussed in terms of their theoretical and practical implications.

This thesis presents the development of an in-wheel drive system consisting of an axial-flux switched-reluctance motor and a hub suspension. The motor is designed using Maxwell's stress tensor and numerical analysis techniques, including FEA and transient numerical simulations. A new integral inductance function is introduced that improves the accuracy of the motor model, and a new in-phase current-shaping technique is implemented using a fuzzy controller to extend the constant-power region of the motor. The hub suspension system is simulated using a half-car model with 6 degrees of freedom, and the overall torque, power, and efficiency of the drive system is calculated. A peak torque of 500[Nm] is developed at the high end of the drive system's speed range, and the hub suspension system is shown to eliminate the impact of the motor's increased unsprung mass on vehicle handling.

In many studies efforts are made to decrease the energy consumption of trains by optimizing their drive style, e.g. accelerate and brake optimally and regenerate electricity when braking. In other studies the goal is to distribute the run time between stations in an optimal way to decrease the energy consumption, given a relatively simple drive style. In this report the goal is to combine these two energy saving methods to obtain as low energy consumption as possible. By coupling one software containing a drive style optimizer with another software which by different optimization methods calculates the optimal run time distribution on a given track this is accomplished. The study also contains a comparison between drive styles, with the goal to find a relatively simple but energy efficient drive style. Finally the dependence between run time distribution and energy consumption is further analysed. The results show that by redistributing the run times the energy consumption can be decreased compared to previously existing time tables. They also show that a relatively simple drive style gives comparable energy consumption compared to the one obtained using a drive style optimizer. Finally the results show that the dependence between run time and energy consumption can be approximated with a simple second order equation.