Solid-State Transformers for Interfacing Solar Panels to the Power Grid: An Optimum Design Methodology of a High Frequency Transformer for dc-dc Converter Applications

Nowadays the use of power electronic interfaces to integrate distributed generation with the power grid is becoming relevant due to the increased penetration of renewable energy sources like solar, and the continued interest to move to a smarter and more robust electric grid. Those interfaces, which also provide a voltage step-up or step-down function, are of particular interest because renewable energy sources do not always have voltages compatible with the connecting grid. Among them, the so-called “power electronic transformer” or “solid-state transformer” (SST) is the focus of significant research. Advantages such as bidirectional power flow, improved system control, reduced size, and premium power quality at the output terminals, increase the interest of the SST for future electric grids. The SST consists mainly of two components: a high-frequency transformer (made out of advanced magnetic materials) and power converters (employing efficient power semiconductor devices like those based on silicon carbide (SiC)) to enable operation at frequencies higher than the grid frequency. This paper presents an optimum design method that can be employed to build a high-frequency transformer for a SST intended to interface a renewable energy source (e.g., a photovoltaic system) to the electric grid. Core material, geometry, and size will be analyzed in order to provide an optimum balance between cost, efficiency, thermal management, and size. Special consideration will also be given to the selection of the winding conductors given the skin effect associated with operation at high frequencies

On the benefits of philosophy as a way of life in a general introductory course

Philosophy as a way of life (PWOL) places investigations of value, meaning, and the good life at the center of philosophical investigation, especially of one’s own life. I argue PWOL is compatible with general introductory philosophy courses, further arguing that PWOL-based general introductions have several philosophical and pedagogical benefits. These include the ease with which high impact practices, situated skill development, and students’ ability to ‘think like a disciplinarian’ may be incorporated into such courses, relative to more traditional introductory courses, as well as the demonstration of philosophy’s value to students by explicitly tying philosophical investigation to students own lives

Design and Control of a Bidirectional Dual Active Bridge DC-DC Converter to Interface Solar, Battery Storage, and Grid-Tied Inverters

In order to further reduce the size of today’s power converters, wide bandgap semiconductor technologies are being explored. These devices, such as silicon carbide (SiC), have been shown to outperform their silicon counterparts when used in high frequency switching, high temperature, and high voltage applications. These properties make them highly desirable in the bidirectional dual active bridge power converter. Being an isolated converter topology, the dual active bridge employs a transformer to provide step-up/step-down functionality and galvanic isolation for the converter. Transformers, as well as other passive components such as inductors and capacitors may be reduced in size when higher switching frequencies are employed. SiC devices used in this application can in turn provide a means to shrink overall system size and increase the power density of the converter, proving further the viability of power electronic systems in applications that require compactness and high efficiency. The aim of this thesis is to demonstrate the performance benefits of SiC MOSFETs in the dual active bridge topology. A justification for the choice of topology is included in this work, along with all of the appropriate design considerations and analysis, leading to the design of a 2kW dual active bridge converter. Modern modeling techniques are also explored and used to develop an enhanced digital controller, implemented in a DSP, for steady state reference tracking and load disturbance rejection. A demonstration of the designed converter verifies the analysis techniques explained therein

Gyromagnetic Ratios for Iron, Cobalt and Certain Binary Alloys of Iron, Cobalt and Nickel

Gyromagnetic ratios for iron, cobalt and many binary alloys of iron, cobalt and nickel were determined by measurements on the Einsten-de Haas effect such as made in this laboratory previously. Improvements were made in the methods of eliminating large quadrature torques. For each series of binary alloys the gyromagnetic ratio was found to vary linearly or nearly linearly with concentra­tion. For those materials studied here previously there is good agreement between the new results and the older

Un algoritmo FFD-Eficiente para resolver el problema de corte de guillotina con demanda no unitaria de requerimientos sobre stock de tamaño variado

Resuelve el problema Guillotine Cutting Stock Problem with Demand on Varied Stock (GCSP-DVS) a través de un algoritmo FFD-Eficiente variado (FFD-E 2DGV). Además, demuestra la capacidad del algoritmo propuesto para incidir en el ahorro significativo a través del reúso de materia prima reciclable para el proceso industrial de corte bidimensional. Asimismo, compendia los resultados del algoritmo propuesto aplicado al GCSP-DVS y los resultados comparativos entre el FFD y el FFD-E aplicado al GCSP-D; generando un banco inédito para instancias de cortes 2 dimensiones de tipo guillotina sobre stock de tamaño variado y otra de demostraciones numéricas comparativas del FFD-E respecto al FFD, respectivamente. Finalmente, implementa un sistema computacional parametrizable que ejecute el algoritmo propuesto y arroje reportes de solución del citado problema GCSP con demanda sobre stock variado (GCSP-DVS).Tesi

ESTIMATION OF THE SPACE SHUTTLE ROLLOUT FORCING FUNCTION

The Space Shuttle Vehicle is assembled in the Vertical Assembly Building (VAB) at Kennedy Space Flight Center in Florida. The Vehicle is stacked on a Mobile Launch Platform (MLP) that weighs eight million pounds. A Crawler Transporter (CT) then carries the MLP and the stacked vehicle (12 million pounds total weight) to the launch complex located 5 miles away. This operation is performed at 0.9 mph resulting in a 4.5-hour transport. A recent test was performed to monitor the dynamic environment that was produced during rollout. It was found that the rollout is a harmonic-rich dynamic environment that was previously not understood. This paper will describe work that has been performed to estimate the forcing function that is produced in the transportation process. The rollout analysis team has determined that there are two families of harmonics of the drive train, which excite the system as a function of CT speed. There are also excitation sources, which are random or narrow-band in frequency and are not a function of CT speed. This presentation will discuss the application of the Sum of Weighted Accelerations Technique (SWAT) to further refine this understanding by estimating the forces and moments at the center-of-mass

Teaching Synthesis

Students will learn how to synthesize information from sources.https://digitalcommons.csumb.edu/teaching_all/1020/thumbnail.jp

Роль корпоративной культуры в системе мотивации труда

OBJECTIVES: Multimorbidity is common in the older population, but the impact of combinations of chronic conditions on disability and quality of life (QoL) is not well known. This analysis explores the effect of specific combinations of chronic diseases on disability, QoL and self-rated health (SRH). DESIGN: We used data from two population representative cross-sectional studies, the Northern Ireland Health and Social Wellbeing Survey (NIHSWS) 2005 and the Survey of Lifestyle, Attitudes and Nutrition (SLAN) 2007 (conducted in the Republic of Ireland). SETTING: Randomly selected community-living participants were interviewed at home. PARTICIPANTS: A total of 6159 participants aged 50 years and older were included in the analysis. OUTCOME MEASURES: Chronic conditions were classified as cardiovascular disease, chronic pain, diabetes or respiratory disease. Interaction terms estimated by logistic regression were used to examine the effects of multiple chronic conditions on disability, SRH and QoL. RESULTS: Each chronic condition group was correlated with each of the others after adjusting for sociodemographic factors. Those from Northern Ireland were more likely to report a limitation in daily activities (45%) compared to those from the Republic of Ireland (21%). Each condition had an independent effect on disability, SRH and QoL, and those with multiple chronic conditions reported the worst outcomes. However, there were no statistically significant positive interactions between chronic condition groups with respect to any outcome. CONCLUSIONS: Chronic conditions affect individuals largely independent of each other with respect to their effect on disability, SRH and QoL. However, a significant proportion of the population aged 50 years and over across the island of Ireland lives with multimorbidity, and this group is at the highest risk of disability, poor SRH and poor QoL