Дисертації з теми "El Niño current Mathematical models"
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Schliemann, Bernd F. "Analysis and modeling of the initiative tenet of current army operations doctrine." Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/25091.
Повний текст джерелаHall, David Eric. "Transient thermal models for overhead current-carrying hardware." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/17133.
Повний текст джерелаHeger, Walter. "Using the finite difference and the finite element method to solve an electric current diffusion problem." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66150.
Повний текст джерелаBhattacharya, Subroto. "Simulation of transient phenomena in high voltage direct-current converter systems." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26959.
Повний текст джерелаApplied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
Howe, Maureen E. "The convenience yield : a model and empirical examination of the relationship between commodity futures prices and current spot prices." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/27320.
Повний текст джерелаBusiness, Sauder School of
Finance, Division of
Graduate
Ansari, Fardin. "Circuit Modeling of Switched Linear Networks." PDXScholar, 1994. https://pdxscholar.library.pdx.edu/open_access_etds/4658.
Повний текст джерелаRoberts, Craig Arnold. "Modeling the relationships between microscopic and macroscopic travel activity on freeways : bridging the gap between current travel demand models and emerging mobile emission models." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/32873.
Повний текст джерелаBocquet, Francois-Xavier. "Investigations of current build up in topologically simple magnetic fields." Thesis, University of St Andrews, 2005. http://hdl.handle.net/10023/11291.
Повний текст джерелаBowness, Ruth. "Current sheets in the solar corona : formation, fragmentation and heating." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/2081.
Повний текст джерелаCirano, Mauro School of Mathematics UNSW. "Wintertime Circulation within the Southeast Indian Ocean: a Numerical Study." Awarded by:University of New South Wales. School of Mathematics, 2000. http://handle.unsw.edu.au/1959.4/17820.
Повний текст джерелаYu, Chang, and 余暢. "An investigation of subsynchronous oscillation of AC/DC power systems: modeling and analysis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37151885.
Повний текст джерелаGaraba, Masimba. "The current role of modern portfolio theory in asset management practice in South Africa." Thesis, Rhodes University, 2005. http://hdl.handle.net/10962/d1002699.
Повний текст джерелаStevenson, Julie E. H. "On the properties of single-separator MHS equilibria and the nature of separator reconnection." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/6678.
Повний текст джерелаRoufberg, Lewis Marlin. "DC analysis of quasi-resonant buck and forward converters including effects of parasitic elements." Thesis, Virginia Tech, 1987. http://hdl.handle.net/10919/45924.
Повний текст джерелаThe need for smaller and more efficient power supplies steadily grows. Many power supplies incorporate high-frequency dc-to-dc switching converters to meet these demands. Recently, a new class of switching converters has been introduced which can operate at very high frequencies to further reduce size and increase efficiency. They are called quasi-resonant converters. Previously, the dc characteristics of many of these converters had been determined, assuming ideal components and circuit operating conditions. However, as the frequency of operation increases, the circuit behavior becomes less ideal causing changes in the expected characteristics. This is because resistive losses, semiconductor junction capacitances, and other parasitic (undesirable) elements become more pronounced at higher frequencies.
This thesis investigates the effects of parasitic elements on the dc characteristics of several zero-current-switched, buck-derived quasi-resonant converters. For the quasi-resonant buck converter, it is demonstrated that for certain operating conditions the dc voltage gain can increase when parasitic losses are increased. Design guidelines are given for maximizing this converterâ s efficiency. Various forward quasi-resonant topologies are investigated, and the effects of parasitic elements on circuit operation are highlighted. A dc analysis is performed for the secondary-resonance forward converter, which has not previously been analyzed. This converter can operate either in full-wave or half-wave mode. Its dc voltage gain in full-wave mode is less sensitive to load variations than { other resonant forward topologies that only operate in ha1f-wave mode.
Master of Science
Conaway, Matthew James. "A theory of calcium dynamics in generating force and low-frequency fatigue in paralyzed human soleus." Diss., University of Iowa, 2010. https://ir.uiowa.edu/etd/656.
Повний текст джерелаZelenke, Brian Christopher. "An empirical statistical model relating winds and ocean surface currents : implications for short-term current forecasts." Thesis, Connect to the title online, 2005. http://hdl.handle.net/1957/2166.
Повний текст джерелаDevlin, Adam Thomas. "On the variability of Pacific Ocean tides at seasonal to decadal time scales| Observed vs modelled." Thesis, Portland State University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10128376.
Повний текст джерелаOcean tides worldwide have exhibited secular changes in the past century, simultaneous with a global secular rise in mean sea level (MSL). The combination of these two factors contributes to higher water levels, and may increase threats to coastal regions and populations over the next century. Equally as important as these long-term changes are the short-term fluctuations in sea levels and tidal properties. These fluctuations may interact to yield locally extreme water level events, especially when combined with storm surge. This study, presented in three parts, examines the relationships between tidal anomalies and MSL anomalies on yearly and monthly timescales, with a goal of diagnosing dynamical factors that may influence the long-term evolution of tides in the Pacific Ocean. Correlations between yearly averaged properties are denoted tidal anomaly trends (TATs), and will be used to explore interannual behavior. Correlations of monthly averaged properties are denoted seasonal tidal anomaly trends (STATs), and are used to examine seasonal behavior. Four tidal constituents are analyzed: the two largest semidiurnal (twice daily) constituents, M2 and S2, and the two largest diurnal (once daily) constituents, K1 and O1.
Part I surveys TATs and STATs at 153 Pacific Ocean tide gauges, and discusses regional patterns within the entire Pacific Ocean. TATs with statistically significant relations between MSL and amplitudes (A-TATs) are seen at 89% of all gauges; 92 gauges for M2, 66 for S2, 82 for K1, and 59 for O1. TATs with statistically significant relations between tidal phase (the relative timing of high water of the tide) and MSL (P-TATs) are observed at 55 gauges for M2, 47 for S2, 42 for K1, and 61 for O1. Significant seasonal variations (STATs) are observed at about a third of all gauges, with the largest concentration in Southeast Asia. The effect of combined A-TATs was also considered. At selected stations, observed tidal sensitivity with MSL was extrapolated forward in time to the predicted sea level in 2100. Results suggest that stations with large positive combined A-TATs produce total water levels that are greater than those predicted by an increase in MSL alone, increasing the chances of high-water events.
Part II examines the mechanisms behind the yearly (TAT) variability in the Western Tropical Pacific Ocean. Significant amplitude TATs are found at more than half of 26 gauges for each of the two strongest tidal constituents, K1 (diurnal) and M2 (semidiurnal). For the lesser constituents analyzed (O1 and S2), significant trends are observed at ten gauges.
Part III analyzes the seasonal behavior of tides (STATs) at twenty tide gauges in the Southeast Asian waters, which exhibit variation by 10 – 30% of mean tidal amplitudes. A barotropic ocean tide model that considers the seasonal effects of MSL, stratification, and geostrophic and Ekman velocity is used to explain the observed seasonal variability in tides due to variations in monsoon-influenced climate forcing, with successful results at about half of all gauges. The observed changes in tides are best explained by the influence of non-tidal velocities (geostrophic and Ekman), though the effect of changing stratification is also an important secondary causative mechanism.
From the results of these surveys and investigations, it is concluded that short-term fluctuations in MSL and tidal properties at multiple time scales may be as important in determining the state of future water levels as the long-term trends. Global explanations for the observed tidal behavior have not been found in this study; however, significant regional explanations are found at the yearly time scale in the Solomon Sea, and at the seasonal time scale in Southeast Asia. It is likely that tidal sensitivity to annual and seasonal variations in MSL at other locations also are driven by locally specific processes, rather than factors with basin-wide coherence. (Abstract shortened by ProQuest.)
Краснов, Роман Володимирович, Роман Владимирович Краснов та Roman V. Krasnov. "Підвищення надійності електродвигунів компресорів електропоїздів постійного струму". Thesis, Видавництво Дніпропетровського національного університету залізничного транспорту імені академіка В. Лазаряна, 2012. http://eadnurt.diit.edu.ua:82/jspui/handle/123456789/1227.
Повний текст джерелаUK: АНОТАЦІЯ Дисертація присвячена підвищенню надійності електродвигунів компресорів електрорухомого складу шляхом забезпечення нормованих значень нагрівання ізоляції в реальних умовах експлуатації і удосконалення системи захисту якірно-го кола електродвигуна від надмірних струмів, які можуть викликати нагрівання ізоляції більше допустимих значень. Пропонується, на відміну від попередніх досліджень, процес пуску розгля-дати таким, що складається з двох етапів. В роботі проведено дослідження по визначенню значень струмів на кожному з цих етапів і впливу тривалості етапів на нагрівання ізоляції. Для теоретичних досліджень автором запропонована ма-тематична модель, адекватність якої підтверджена тим, що різниця між параме-трами, які отримані з допомогою цієї моделі та експериментально (шляхом ос-цилографування), знаходиться в межах до 5 %. Отримані залежності тривалості першого та другого етапів пуску, а також значень струму якоря на цих етапах при різних умовах: різних значеннях на-пруги в контактній мережі, температурі навколишнього середовища, тиску в пневмомережі та значенням моменту на валу двигуна після закінчення пуску. Експериментально та теоретично доведено, що в окремих випадках захист електродвигуна з допомогою теплового реле ТРВ-8,5 не забезпечується. З допомогою теплової моделі досліджені процеси нагрівання ізоляції обмо-тки якоря під час пуску та подальшої роботи електродвигуна компресора при різних можливих режимах та умовах. Результати досліджень, що отримані за допомогою математичної та тепло-вої моделей використані для програмування нового пристрою захисту електро-двигуна компресора від перенавантажень. Запропонований пристрій захисту безвідмовно протягом декількох років працює на реальному електропоїзді. RU: АННОТАЦИЯ Диссертация посвящена повышению надежности электродвигателей ком-прессоров электроподвижного состава путём обеспечения рациональных значе-ний нагревания изоляции в реальных условиях эксплуатации и усовершенство-вания системы защиты якорной цепи электродвигателя от чрезмерных токов, которые могут вызвать нагревание изоляции больше нормированных значений. Проведен анализ выхода из строя электродвигателей компрессоров на электропоездах постоянного тока серии ЭР-1, 2 по причине пробоя изоляции обмоток якоря и полюсов. Как показывает обзор литературы по теме диссерта-ционной работы, проведенный автором, до теперешнего времени влияние про-цесса пуска на нагревание изоляции обмоток якоря и полюсов в полной мере не исследовано, особенно это относится к рассмотрению процесса пуска как тако-вого. Автор, в отличие от предыдущих исследований, предлагает процесс пуска рассматривать состоящим из двух этапов. Первый этап пуска – напряжение на электродвигатель подано, а его вал не вращается в течении некоторого времени. Второй этап – вал электродвигателя трогается и начинает набирать обороты до установившегося значения угловой скорости. В работе проведено исследование по определению значений токов на каж-дом из этих этапов и влиянию длительности этапов на нагревание изоляции. Для этого вначале проведено экспериментальное исследование процессов пуска электродвигателя компрессора на реальном электропоезде путем осциллогра-фирования этого процесса с помощью современного измерительного комплекса с исользованием датчиков напряжения (тип LEM CV4-6000) и тока (тип LEM LT100-8/SP30). Для теоретических исследований автором предложена математическая мо-дель, адекватность которой подтверждена тем, что расхождение параметров, полученных путем осциллографирования и с помощью математической модели находится в пределах до 5 %. Для получения численных значений при исследо-вании процессов пуска на указанных двух этапах с помощью математической модели используется метод Рунге-Кутта-Фелберга. Получены зависимости тока якоря на первом и втором этапах пуска при разных условиях: разных значениях напряжения в контактной сети, температу-ры окружающей среды, давления в пневматической сети. Получены также зависимости длительности первого и второго этапов пус-ка от указанных условий. Установлено, что в реальных условиях эксплуатации длительность первого этапа пуска составляет от 19 до 74 мс, однако, несмотря на относительно малое значение, токи, возникающие на первом этапе, существенно влияют на эффек-тивное значение тока за всё время пуска и соответственно существенно влияют на нагревание изоляции. Так увеличение длительности первого этапа пуска до 30 % по сравнению с пуском электродвигателя при номинальном напряжении в контактной сети и нормальных внешних условиях увеличивает эквивалентный ток за всё время пуска до 9,1 %. Установлены зависимости между длительностью первого этапа и значени-ем момента на валу двигателя после окончания пуска. Экспериментальные и теоретические исследования показали, что в отдель-ных случаях защита электродвигателя с помощью теплового реле ТРВ-8,5 не обеспечивается. С помощью тепловой модели исследованы процессы нагревания изоляции обмотки якоря во время пуска и дальнейшей работы электродвигателя компрес-сора при номинальной нагрузке на его валу и при бо́льших нагрузках, что воз-можно при реальных условиях эксплуатации. Доказано, что в эксплуатации возможны режимы работы, при которых из – за перегрева изоляции срок её службы снижается до 4,8 лет, что соответствует статистическим данным. Установлена зависимость времени, за которое протекание тока определён-ного значения приводит к максимально допустимому нормированному нагре-ванию изоляции обмоток якоря от этого тока при наиболее неблагоприятной температуре окружающей среды – +40 ˚С. Эта зависимость использована для программирования предложенного автором нового устройства защиты якорных цепей на базе современных микроконтроллеров. Предложенное автором устройство защиты от перегрузок электродвигателя компрессора безотказно в течение нескольких лет работает на реальном элек-тропоезде. Проведено технико – экономическое обоснование внедрения результатов работы. EN: ABSTRACT The dissertation paper is devoted to improving the reliability of electromotor compressors of rolling stock by providing normative values of heat insulation under real operating conditions and improve protection anchor range from excessive elec-tric currents that can cause heat insulation more acceptable values. Proposed, in contrast to previous studies, the process of starting to consider as being composed of two stages. In this paper a study to determine the values of currents at each of these phases and the influence of the duration of the stages of heat insulation. For theoretical investigations of the author to proposed mathematical model, whose adequacy is confirmed that the difference between the parameters ob-tained using this model and experimentally (by oscillography) is within 5%. Dependences of the duration of the first and second stages of start-up and current values of anchor on these stages under different conditions: different values of voltage in the contact system, ambient temperature, air pressure in the pneumatic system and the value of the moment on the shaft of the electric motor after starting. Experimentally and theoretically shown that in some cases protection of the electric motor with thermal relay ТРВ-8, 5 is not provided. With the thermal model the processes of heat insulation of armature winding during start-up and subsequent operation of the electric motor of compressor for various possible modes and conditions are investigated. The research results, obtained by using mathematical and thermal models, used for programming a new protection device of electric motor compressor from overload. The proposed protection device flawlessly for several years working on real electric rolling stock.
Peery, Jeffrey B. "State space modeling of alternating-current thin-film electroluminescent devices." Thesis, 1997. http://hdl.handle.net/1957/34152.
Повний текст джерелаLange, Jarren Hilton. "Practical considerations when inferring lightning current from electric field recordings with a high noise-floor." Thesis, 2015. http://hdl.handle.net/10539/22695.
Повний текст джерелаDuring a cloud to ground lightning event a charge centre within the storm cloud is discharged. The discharge of a charge centre within the cloud leads to a change in the electric eld radiated by the charge centre. It is theoretically possible to infer the lightning current from the derivative of the electric eld. It is only possible to infer the lightning current from the electric eld data where the noise is comparatively much smaller than the electric eld data. The changing electric elds for a lightning event that occurred on the 3rd January 2015 13:15:13 were recorded by a at plate electric eld sensor with a passive integrator. The oscilloscope used to capture the electric eld data has a relatively large measurement noise and a low resolution. A low pass digital lter was applied to the recorded electric eld data to reduce the e ects from the high frequency noise. The lightning strokes were recorded by the South African Lightning Detection Network. The Lightning Detection Network data is used to obtain the distance of the lightning event from the sensor, to scale the inferred lightning current. The Lightning Detection Network also provides a lightning peak current measurement to compare to the peak current inferred from the electric eld data. The lightning stroke current was inferred from the electric eld recording for various bandwidths of the low pass lter. Inconsistent changes to the inferred lightning stroke current as the lter bandwidth is changed shows that the frequency components for each stroke di ers. The peak stroke current was not constant for any lter bandwidth range implying that the measurement noise is relatively too large. The case study presented demonstrates that with a relatively large noise magnitude (3 to 4 discrete steps of the digital recording) compared to the electric eld signal (21 discrete steps) it is di cult to accurately infer the lightning current from the electric elds recorded.
MT2017
"Study of El Niño-southern oscillation phenomenon by using an intermediate coupled model =: 利用中介耦合模型對厄爾尼諾/南方濤動現象進行之硏究". 2002. http://library.cuhk.edu.hk/record=b5895990.
Повний текст джерелаThesis (M.Phil.)--Chinese University of Hong Kong, 2002.
Includes bibliographical references (leaves 120-122).
Text in English; abstracts in English and Chinese.
by Yeung Wai Lung.
Abstract --- p.i
Abstract (Chinese version) --- p.ii
Acknowledgements --- p.iii
Contents --- p.iv
List of figures --- p.vii
List of tables --- p.xi
Chapter 1 --- Introduction --- p.1
Chapter 2 --- The El Nino ´ؤ Southern Oscillation Phenomenon --- p.3
Chapter 2.1 --- Introduction to El Nino - Southern Oscillation --- p.3
Chapter 2.2 --- The mean conditions of the Tropical Ocean --- p.4
Chapter 2.3 --- Life Cycle of ENSO --- p.8
Chapter 2.4 --- Understanding ENSO --- p.12
Chapter 3 --- ENSO prediction schemes --- p.18
Chapter 3.1 --- Introduction --- p.18
Chapter 3.2 --- Statistical prediction models --- p.19
Chapter 3.2.1 --- Introduction --- p.19
Chapter 3.2.2 --- Atmospheric models --- p.19
Chapter 3.2.3 --- Oceanic models --- p.22
Chapter 3.3 --- Coupled ocean-atmosphere models --- p.24
Chapter 3.3.1 --- Introduction --- p.24
Chapter 3.3.2 --- Intermediate coupled models --- p.25
Chapter 3.3.3 --- Hybrid coupled models --- p.28
Chapter 3.3.4 --- Coupled general circulation models --- p.30
Chapter 3.4 --- Skill sensitivities --- p.36
Chapter 3.4.1 --- Introduction --- p.36
Chapter 3.4.2 --- Dependence of skill on season --- p.36
Chapter 3.4.3 --- Dependence of skill on decade --- p.37
Chapter 3.4.4 --- Dependence of skill on the Phase of the ENSO cycle --- p.38
Chapter 4 --- The ENSO model --- p.40
Chapter 4.1 --- Introduction --- p.40
Chapter 4.2 --- Models formalism --- p.40
Chapter 4.2.1 --- Oceanic model --- p.40
Chapter 4.2.2 --- Atmospheric model --- p.43
Chapter 4.2.3 --- Coupling of atmospheric and oceanic models --- p.44
Chapter 4.3 --- Numerical implementation --- p.45
Chapter 4.3.1 --- Oceanic model --- p.45
Chapter 4.3.2 --- Atmospheric model --- p.49
Chapter 4.3.3 --- Averaging and interpolation during coupling --- p.52
Chapter 4.4 --- Standard response of the model --- p.54
Chapter 4.5 --- Limitation of the model --- p.57
Chapter 5 --- Behavior of the ENSO model --- p.59
Chapter 5.1 --- Introduction --- p.59
Chapter 5.2 --- Numerical results of the model --- p.60
Chapter 5.3 --- Effects of the parameters --- p.62
Chapter 5.3.1 --- Introduction --- p.62
Chapter 5.3.2 --- Coupling constant parameters --- p.62
Chapter 5.3.3 --- Rayleigh friction --- p.66
Chapter 5.3.4 --- The oceanic Kelvin wave speed --- p.69
Chapter 5.3.5 --- The ocean basin length --- p.69
Chapter 5.3.6 --- Reflections at the western boundary --- p.74
Chapter 5.4 --- Modification of the model background state --- p.76
Chapter 5.4.1 --- Introduction --- p.76
Chapter 5.4.2 --- The results of the modified model --- p.77
Chapter 5.4.3 --- Sensitivity of the western boundary of the modified model --- p.81
Chapter 5.4.4 --- Parameters sensitivities of the modified model --- p.83
Chapter 5.5 --- Conclusion and discussion --- p.87
Appendix A --- p.91
Appendix B --- p.112
Bibliography --- p.120
Li, Xiaowei 1970 May 5. "High-speed and high-saturation-current partially depleted absorber photodetecters [i.e. photodetectors." 2004. http://hdl.handle.net/2152/12696.
Повний текст джерелаDixit, Sanjay. "Simulation of tropical pacific circulation anomalies with linear atmosphere and ocean models." Thesis, 1987. http://hdl.handle.net/1957/28619.
Повний текст джерелаGraduation date: 1988
Ahn, Joong Bae. "A study of El Niño/southern oscillation : numerical experiments and data analysis." Thesis, 1990. http://hdl.handle.net/1957/29066.
Повний текст джерелаGraduation date: 1991
Ruttanapaibooncharoen, Surin. "Improved efficiency in medium-power flyback converters." Thesis, 2003. http://hdl.handle.net/1957/30228.
Повний текст джерелаGraduation date: 2004
Lacave, Benoit. "Modelling and control of a co-current sugar dryer." Thesis, 2001. http://hdl.handle.net/10413/9056.
Повний текст джерелаThesis (M.Sc.Eng.)-University of Natal, Durban, 2001.
Lee, Yuan-chun Harry. "The simulated effect of the lightning first short stroke current on a multi-layered cylindrical model of the human leg." Thesis, 2015. http://hdl.handle.net/10539/22609.
Повний текст джерелаThis research investigates the e ects of the frequency components of the lightning First Short Stroke (FSS) on the current pathway through human tissues using frequency domain analysis. A Double Exponential Function (DEF) is developed to model the FSS with frequency components in the range 10 Hz 100 kHz. Human tissues are simulated using Finite Element Analysis (FEA) in COMSOL and comprises of two types of models: Single Layer Cylindrical Model (SLCM) and Multi-layered Cylindrical Model (MLCM). The SLCM models 54 human tissues independently and the MLCM models the human leg with ve tissue layers: bone marrow, cortical bone, muscle, blood and fat. Three aspects are analysed: current density, complex impedance and power dissipation. From the SLCM results, aqueous tissues have the lowest impedances and tissue heat dissipation is proportional to tissue impedance. Results from the MLCM show that 85% of the FSS current ows through muscle, 11% ows through blood, 3:5% through fat and the rest through cortical bone and bone marrow. From the results, frequency dependent equivalent circuit models consisting of resistors and capacitors connected in series are proposed. The simulation results are correlated with three main clinical symptoms of lightning injuries: neurological, cardiovascular and external burns. The results of this work are applicable to the analysis of High Voltage (HV) injuries at power frequencies.
MT2017
Liu, Kaiyang. "A Selective Polarity DC-DC Converter with Virtually Infinite Voltage Levels." Thesis, 2016. http://hdl.handle.net/1805/10929.
Повний текст джерелаThis research introduces a new design of a converter modified from SEPIC converter (Single end primary inductive converter), capable of generating desired voltage levels and polarities. The new switching converter topology allows for boost and buck of the input voltage theoretically achieving infinite positive and negative voltage levels. The proposed topology utilizes single high frequency switch to perform the power conversion which simplifies the design of the gate driver, but meanwhile, it still retains the ability to provide a wide range of output voltage. Mathematical modeling of the converter and computer simulations are validated by experimental data. To verify its performance a prototype was designed and built. It is experimentally proven that the circuit can generate a desired voltage in the range of voltages up to ±170 V, delivering 480 Watts of power to a resistive load.
Triggs, Adam. "Macroeconomics and multilateralism: The benefits and influence of global macroeconomic policy cooperation." Phd thesis, 2018. http://hdl.handle.net/1885/149501.
Повний текст джерелаSajadian, Sally. "Energy conversion unit with optimized waveform generation." Thesis, 2014. http://hdl.handle.net/1805/6109.
Повний текст джерелаThe substantial increase demand for electrical energy requires high efficient apparatus dealing with energy conversion. Several technologies have been suggested to implement power supplies with higher efficiency, such as multilevel and interleaved converters. This thesis proposes an energy conversion unit with an optimized number of output voltage levels per number of switches nL=nS. The proposed five-level four-switch per phase converter has nL=nS=5/4 which is by far the best relationship among the converters presented in technical literature. A comprehensive literature review on existing five-level converter topologies is done to compare the proposed topology with conventional multilevel converters. The most important characteristics of the proposed configuration are: (i) reduced number of semiconductor devices, while keeping a high number of levels at the output converter side, (ii) only one DC source without any need to balance capacitor voltages, (iii) high efficiency, (iv) there is no dead-time requirement for the converters operation, (v) leg isolation procedure with lower stress for the DC-link capacitor. Single-phase and three-phase version of the proposed converter is presented in this thesis. Details regarding the operation of the configuration and modulation strategy are presented, as well as the comparison between the proposed converter and the conventional ones. Simulated results are presented to validate the theoretical expectations. In addition a fault tolerant converter based on proposed topology for micro-grid systems is presented. A hybrid pulse-width-modulation for the pre-fault operation and transition from the pre-fault to post-fault operation will be discussed. Selected steady-state and transient results are demonstrated to validate the theoretical modeling.