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1
Illias, Hazlee Azil. „Measurement and simulation of partial discharges within a spherical cavity in a solid dielectric material“. Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/194921/.
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For high voltage components, the measurement of partial discharge (PD) is used in the performance assessment of an insulation system. Through modelling the PD process, a better understanding of the phenomenon may be attained. In this work, a model for a spherical cavity within a homogeneous dielectric material has been developed using Finite Element Analysis (FEA) software in parallel with MATLAB programming code. The model has been used to study the effect of various applied stresses and cavity conditions on PD activity and also the electric field and temperature distributions within the cavity. The experimental measurement of PD activity within a spherical cavity has also been undertaken. The measurements were performed for different amplitudes and frequencies of the applied voltage, a range of spherical cavity sizes and temperature variation of the material. The obtained results show that PD is strongly influenced by various conditions of the cavity and applied stress. The cycle to cycle behaviour of PD events, discharge phase and magnitude distributions, numbers of PDs per cycle, total charge magnitude per cycle, mean charge magnitude and maximum charge magnitude for each experiment have been obtained and analysed. The simulation results from the PD model have been compared with the measurement results. It is found that certain model parameters are dependent on the applied stress and cavity conditions. Parameters that clearly affect PD activity can be readily identifed. These parameters include; the effective charge decay time constant, the cavity surface conductivity, the initial electron generation rate, the inception field, the extinction field and the temperature decay time constant in the cavity. The infuences of surface charge decay through conduction along the cavity wall and temperature and pressure change in the cavity on PD activity have also been studied
2
Tran, Trung Nam. „Surface discharge dynamics : theory, experiment and simulation“. Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/165509/.
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The use of solid insulators in electrical generation, transmission and distribution is widespread. However, the accumulation of charge on the insulator surface has proved to be one of the major factors contributing to system failures. This research work is aimed at studying the dynamics of surface discharge in theory, by simulation and experiment. Different surface charging theories have been reviewed and classiffied according to electric field uniformity. The focus is on basic processes involved in the formation of positive and negative surface discharges. The experimental work utilises the non-destructive quantitative Pockels technique to measure surface charge density distribution. Practical considerations of the Pockels experiment together with image processing techniques are discussed in detail. Using this technique, various factors which influence the surface discharge dynamics have been studied including the effects of the applied voltage waveform, electrode shape and local gaseous environment. Results obtained using positive/negative square wave, ramp and sinusoidal voltages are reported. The impact of using a mushroom electrode instead of a needle electrode is also analysed. In addition, various insulation gases have been experimented namely dry air, N2, CO2 and their mixtures with SF6. Surface discharge measurements have been performed in these gases at various levels of pressure. Surface discharge modelling and simulation studies have also been undertaken. The simulation principles are based on a system of coupled hydrodynamic equations consisting of continuity and Poisson's equations. By solving these equations, the movement and interaction of charged particles and transient electric eld can be simulated and used to verify the discharge theories and experimental results. Due to the asymmetric lamentary nature of positive surface streamers, the development of a positive surface discharge is separated into two phases. The rst phase involves the axial streamer development in the gas gap between the needle electrode and the dielectric surface. This phase is simulated in 2D axial symmetry space dimension by the nite element package COM-SOL. The second phase simulates the streamer propagation in 1D along the dielectric surface by using the eld results from the rst phase. This part of the model is solved by the accurate ux-corrected transport algorithm. The effects of model parameters on the simulation results are discussed and a comparison with experimental data made. Prior to the simulation of a negative surface discharge, a negative corona discharge model in 2D axial symmetry has been analysed (Trichel pulses). The model behaviour is studied with reference to experimental data as model parameters are varied. When the insulators are introduced, the accumulation of surface charge distorts the electric eld leading to the formation of only one discharge current pulse. The simulation charge density distribution is in good agreement with results obtained from the Pockels experiment.
3
Vieira, Marcos Stefanelli. „Influência das edificações na propagação de ondas eletromagnéticas geradas por descargas atmosféricas“. Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3142/tde-15072016-150045/.
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Descargas atmosféricas representam uma das principais causas de interrupção no fornecimento de energia para os consumidores, e embora tenham efeitos mais intensos quando incidem diretamente nas redes elétricas, é o caso das descargas indiretas que chama mais atenção, já que elas ocorrem com maior frequência. Tanto as primeiras descargas que geralmente ocorrem com maior intensidade de corrente, quanto as descargas subsequentes que têm menor tempo de frente associado, irradiam campos eletromagnéticos que ao se acoplarem com as redes elétricas geram surtos que podem causar tanto a interrupção do fornecimento de energia quanto danos a equipamentos. A presença de edifícios na região de incidência da descarga atmosférica afeta a propagação das ondas irradiadas, criando diferentes padrões de campos resultantes, os quais são responsáveis por sobretensões induzidas. Embora tanto a descarga atmosférica em si quanto a caracterização do ambiente ao seu redor sejam de natureza complexa para sua representação, ferramentas computacionais bem estruturadas podem representar o fenômeno de forma satisfatória, como é o caso da ferramenta computacional desenvolvida neste trabalho utilizando o método das diferenças finitas no domínio do tempo. O presente trabalho apresenta dois estudos para verificação da influência de edificações na propagação de campo irradiado por descargas atmosféricas. O primeiro estudo avaliou o comportamento das componentes do campo elétrico e do campo magnético irradiados, comparando resultados obtidos com e sem a presença de edificações numa pequena região. Tanto os parâmetros geométricos dos três edifícios considerados neste estudo, como a permissividade e a condutividade elétrica do solo e dos edifícios, foram variados para identificar a sua influência nos campos irradiados. Os resultados mostraram diferentes comportamentos das componentes dos campos resultantes em função da variação desses parâmetros, observando-se inversão de polaridade, oscilações na forma de onda e tanto redução quanto aumento do valor de campo. O segundo estudo avaliou um caso mais geral em que a componente vertical de campo elétrico foi tomada em nove pontos diferentes de uma região tipicamente urbana, com a presença de 102 edifícios. Os valores de campo avaliados em cada ponto, dez metros acima do solo, consideraram a incidência aleatória de 28 descargas atmosféricas distintas, cada uma atingindo o topo de um dado edifício. Os resultados desse segundo estudo mostraram que exceto nos casos em que a descarga atmosférica ocorre próximo do ponto analisado, há reduções significativas do campo elétrico vertical. Desta forma é possível perceber que não apenas a existência de edifícios, mas a sua concentração com diferentes características elétricas e geométricas, podem influenciar significativamente a propagação de campo irradiado. Os valores calculados a partir da ferramenta desenvolvida podem ser usados em conjunto com modelos de acoplamento, para o cálculo de sobretensões induzidas em redes elétricas, em situações realistas com configurações mais complexas.Atmospheric discharges represent one of the main causes of interruption in power supply to consumers, and although they have more intense effects when direct impact on energy lines, are the case of indirect discharges that draws more attention, since they occur more frequently. Both the first discharges, occurring generally with greater intensity of current, as subsequent discharges that have shorter front time associated, radiate electromagnetic fields which engage with the electrical networks generating surges that can cause so much disruption of power supply as damage to the equipment. The presence of buildings in the lightning incident area affects the propagation of the radiated waves, creating different patterns of resultant fields, which are responsible for induced overvoltages. Although both the lightning itself and characterization of the surrounding environment are of a complex nature for its representation, structured computational tools can represent satisfactorily the phenomenon, such as the software tool developed here using the finite difference time domain method. This work presents two studies to verify the influence of buildings in the propagation of lightning irradiated field. The first study assessed the behavior of the components of the electric field and magnetic field irradiated, by comparing results obtained with and without the presence of buildings in a small region. Both the geometric parameters of the three buildings considered in this study, as the permittivity and electrical conductivity of the soil and buildings, were changed to identify their influence on radiated fields. The results showed different behaviors of the components of the resulting field due to the variation of these parameters, observing polarity inversion, oscillations in the waveform and either a reduction or increase of the field value. The second study evaluated a more general case where the vertical component of the electric field was taken at nine different points of a typical urban area, in the presence of 102 buildings. The field values evaluated at each point, ten meters above the ground, considered the effect of 28 different random lightning, which hit the top of a given building. The results of this second study showed that except in cases where atmospheric discharge occurs near the analyzed point, there are significant reductions of the vertical electric field. Thus it can be seen that not only the existence of buildings, but its concentration with different electrical and geometrical characteristics, can significantly influence the propagation of irradiated field. The values calculated from the developed tool can be used in conjunction with coupling models for calculating induced overvoltages on power lines, in realistic situations with complex configurations.
4
Yourkowski, Joel. „Computer simulation of an unmanned aerial vehicle electric propulsion system“. Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA307294.
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5
林霙芝 und Ying-chi Lam. „Agent-based simulation of electricity markets“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31222882.
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6
Zaag, Nader. „Fast simulation of cascading outages with islanding“. Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112588.
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This thesis proposes an efficient power system simulator to estimate the automatic sequence of events that follow a fault contingency leading to islanding and cascading outages. The simulator is based on a quasi-steady state model that includes island identification, under-frequency load shedding, over-frequency generator tripping, and island load flow. Contingencies can include the outage of generators, loads, or transmission lines. Often times, a fault of one or two of these power system elements can lead to many cascaded outages and system islanding. The simulator utilizes an innovative method that analyzes the null space of the DC load flow susceptance matrix to identify system islands after each disturbance. Once system islands have been determined, each island power imbalance is calculated and the simulator determines based on the power imbalance in each island whether any load shedding, generator tripping, or primary frequency regulation is required. Once these corrective actions are completed each island will either have been found to balance power or will experience blackout. In the islands that have balanced power, a load flow is computed to see if all line flow constraints are satisfied. Any lines with flow constraint violations are faulted, and the iterative process is repeated under all line flow constraints are satisfied.The results demonstrate the ability of the simulator to quickly and efficiently predict a system's response to contingencies leading to cascading outages and islanding. Simulations were conducted on a 10-bus 13-line network, a 24-bus 38-line network, and a 72-bus 119-line network.
This thesis also examined the highly complex mixed-integer linear problem of identifying the optimum initial outage in the sense that it would cause the maximum amount of load shedding through islanding. The results on a three-line, three-bus test properly identified the line whose initial outage caused overflows leading to system separation and maximum loss of load.
7
Lai, Tsz-ming Terence, und 黎子明. „Harmonic simulation of traction system“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B3122281X.
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8
Arès, Jean-Michel. „A knowledge-based model and simulator for alarm and protection systems of power networks /“. Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63921.
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9
Miyake, Yohei. „Computer Experiments on Electric Antenna Characteristics in Space Plasma Environment“. 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/77978.
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Kyoto University (京都大学)0048
新制・課程博士
博士(工学)
甲第14623号
工博第3091号
新制||工||1460(附属図書館)
26975
UT51-2009-D335
京都大学大学院工学研究科電気工学専攻
(主査)教授 大村 善治, 准教授 松尾 哲司, 准教授 酒井 道
学位規則第4条第1項該当
10
Liao, Jen-Chyi. „Computer simulation of multiple coupled transmission lines in electronic packaging application“. Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184659.
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A method for simulating the transient responses of networks containing lossless transmission lines and lumped parameter elements of circuits, both linear and nonlinear, has been developed and investigated. The method combines the technique of network analysis and that of modal decomposition of transmission lines. A prototype computer simulation program, called UANTL, based on the developed algorithm has been implemented. Several example networks have been simulated using this program. The results have been compared with those generated by the well known circuit simulator program called SPICE. UANTL has shown several advantages over SPICE in simulating the transient responses of networks containing transmission lines. A description of the prototype version of UANTL and a summary of the results of numerical experiments are included.
11
Parikh, Rajiv D. „PC based simulation software package for an uninterruptable power supply“. Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-11242009-020238/.
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12
Atkinson-Hope, Gary. „An integrated programme for power systems simulation using personal computers (PC's)“. Thesis, Cape Technikon, 1993. http://hdl.handle.net/20.500.11838/1147.
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Thesis (Masters Diploma (Technology)--Cape Technikon, Cape Town, 1993The research objectives were to: Formulate a training structure covering conventional power systems topics; Research existing PC based power systems software resources; Develop a structure for a PC based power systems course; Research the capabilities of the software resources chosen; Develop a structure for a modern PC based power systems course taking into account the capabilities and limitations of the selected software programs; Develop for the PC based power systems course, task orientated computer based laboratory set-ups. The set-ups provide: An introduction into the topics concerned; An explanation of the usage of each program applied, where usage means an explanation of the Input and Output Data of each program; User friendly simulation experiments. These set-ups, together with software programs and a personal computer integrate into a training programme and realize a power systems simulation course.
13
Wang, Xiaolin. „Synchronous fault simulation by surrogate with exceptions“. Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184687.
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The contribution of this dissertation is the development of a completely new and accurate algorithm SFSSE for synchronous fault simulation of sequential circuits. The distinctive difference between SFSSE (Synchronous Fault Simulation by Surrogate with Exceptions) and similar approaches for fault simulation in combinational logic circuits is that SFSSE is capable of handling faults stored in more than one memory elements and the reconvergence over time of the stored fault effect with the original fault. The experimental result shows a significant improvement for SFSSE by comparing its execution time to that of parallel fault simulation. After a stored fault list is established during one clock period, all paths from the output of that memory element to the primary outputs might be blocked in subsequent clock periods. A fault is usually propagated through many paths in various subnetworks over several clock periods, and it is detected when only one of these paths reaches a primary output. A new idea for efficiency is suggested in the last chapter to avoid the unproductive simulation activity. In that approach the waste of simulation time is avoided by overlapping the simulation of multiple clock periods.
14
Arata, John Paul III. „Simulation and control strategy development of power-split hybrid-electric vehicles“. Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42790.
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Power-split hybrid-electric vehicles (HEVs) provide two power paths between the internal combustion (IC) engine and the driven wheels through gearing and electric machines (EMs) composing an electrically variable transmission (EVT). EVTs allow IC engine control such that rotational speed is independent of vehicle speed at all times. By breaking the rigid mechanical connection between the IC engine and the driven wheels, EVTs allow the IC engine to operate in the most efficient region of its characteristic brake specific fuel consumption (BSFC) map. If the most efficient IC engine operating point produces more power than is requested by the driver, the excess IC engine power can be stored in the energy storage system (ESS) and used later. Conversely, if the most efficient IC engine operating point does not meet the power request of the driver, the ESS delivers the difference to the wheels through the EMs. Therefore with an intelligent supervisory control strategy, power-split architectures can advantageously combine traditional series and parallel power paths.
In the first part of this work, two different power-split HEV powertrains are compared using a two-term cost function and steady-state backward-looking simulation (BLS). BLS is used to find battery power management strategies that result in minimized fuel consumption over a user-defined drive-cycle. The supervisory control strategy design approach amounts to an exhaustive search over all kinematically admissible input operating points, leading to a minimized instantaneous cost function. While the approach provides a valuable comparison of two architectures, non-ideal engine speed fluctuations result. Therefore, in the second part of the work, two approaches for designing control strategies with refined IC engine speed transitions are investigated using high-fidelity forward-looking simulation (FLS). These two approaches include: i) smoothing the two-term cost function optimization results, and ii) introducing a three-term cost function. It is found that both achieve operable engine speed transitions, and result in fuel economy (FE) estimates which compare well to previous BLS results. It is further found that the three-term cost function finds more efficient operating points than the smoothed two-term cost function approach. From the investigations carried out in parts one and two of this work, a two-phase control strategy development process is suggested where control strategies are generated using efficient steady-state BLS models, and then further tested and verified in high-fidelity FLS models. In conclusion, the FLS results justify the efficacy of the two-phased process, suggesting rapid and effective development of implementable power-split HEV supervisory control strategies.
15
Girouard, Pierre. „Un système expert pour la gestion en temps réel des alarmes dans un réseau électrique /“. Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63940.
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16
Woodburn, David. „Modeling and Simulation of All-electric Aircraft Power Generation and Actuation“. Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6037.
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Modern aircraft, military and commercial, rely extensively on hydraulic systems. However, there is great interest in the avionics community to replace hydraulic systems with electric systems. There are physical challenges to replacing hydraulic actuators with electromechanical actuators (EMAs), especially for flight control surface actuation. These include dynamic heat generation and power management.
Simulation is seen as a powerful tool in making the transition to all-electric aircraft by predicting the dynamic heat generated and the power flow in the EMA. Chapter 2 of this dissertation describes the nonlinear, lumped-element, integrated modeling of a permanent magnet (PM) motor used in an EMA. This model is capable of representing transient dynamics of an EMA, mechanically, electrically, and thermally.
Inductance is a primary parameter that links the electrical and mechanical domains and, therefore, is of critical importance to the modeling of the whole EMA. In the dynamic mode of operation of an EMA, the inductances are quite nonlinear. Chapter 3 details the careful analysis of the inductances from finite element software and the mathematical modeling of these inductances for use in the overall EMA model.
Chapter 4 covers the design and verification of a nonlinear, transient simulation model of a two-step synchronous generator with three-phase rectifiers. Simulation results are shown.Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
17
劉紅進 und Hongjin Liu. „Implementation of a multi-agent based power market simulator“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31224829.
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18
Garrett, Bretton Wayne. „Digital simulation of power system protection under transient conditions“. Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/27303.
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This work demonstrates the use of digital simulation for analyzing protection
system performance. For studies of complex, multi-relay protection systems, digital simulation provides utility engineers with an attractive alternative to relay testing techniques. The cost of digital simulation facilities can be lower than the cost of comparable testing facilities; relay hardware does not have to be made available for the test laboratory.
Digital simulation would ordinarily be impractical for security and dependability studies, due to the thousands of individual simulations involved. The number of simulations needed can be greatly reduced by using a technique called "numerical logic replacement" for implementing the protection scheme logic. This unconventional technique makes near-misoperation visible from individual simulations.
The likelihood of overlooking potential misoperation is thus much lower than with the usual direct (Boolean) implementations.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
19
Onwunta, Onwunta Emea Kalu. „Modelling and simulation of the impacts of distributed generation integration into the smart grid“. Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/1200.
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Thesis submitted in fulfilment of the requirements for the degree
Doctor of Technology: Electrical Engineering
in the Faculty of Engineering
at the Cape Peninsula University of Technology
2014Distributed generation (DG) has been reincarnated after its demise by centralised generation. While economy of scale and efficiency are the advantages of the latter, deregulation of the electricity market, environmental concerns and the need to arrest dwindling reserve margins have necessitated the rebirth of the former. Indeed, a full circle has therefore evolved with generation being ‘embedded’ in distribution systems and ‘dispersed’ around the system rather than being located and dispatched centrally or globally. This development is in tandem with the history of industrial revolutions that started from energy and moved through services and communication and back to energy. South Africa is not immune to the global energy, especially tertiary energy, challenge phenomenon. At the peak of the 2007-2008 energy crisis, her generation net reserve margin fell below 10% – well below conventional industry benchmark of at least 15%. Also South Africa is Africa’s largest emitter of CO2 contributing over 40% of Africa’s total CO2 emissions. Therefore, DG’s relevance to South Africa is quite obvious. However, DG integration into distribution networks leads to a number of challenges. For instance, with significant penetration of DG power flow reversal may be experienced and the distribution network will no longer be a passive circuit. This underscores the crucial role of ICT in active distribution network occasioned by DG and especially the emergent of “prosumerism” (a hitherto consumer also becoming a producer). Therefore, a smart grid and similar phrases have all been used to describe a “digitised” and intelligent version of the present-day power grid. There are immense benefits derivable from modelling and simulation. Consequently, a typical radial distribution network model has been developed to evaluate the considerable impacts of DG integration. The modelling and simulation of the network are accomplished using the DIgSILENT PowerFactory simulation package. Impacts of DG on voltage profile, fault level, voltage stability and protection coordination have been investigated and their possible mitigation measures proferred. The results reveal that for a particular DG type its impacts depend mainly on its capacity and point of connection relative to a given load type. Smart grid technology addresses some of these impacts through its inherent capability which includes peer-to-peer relay communication for protective devices on the distribution feeder as well as communication to the DG facility.
20
Kant, Krishan S. M. Massachusetts Institute of Technology. „Finite element simulation based design and optimization of electric motors for EV/HEV traction application“. Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122551.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 125-129).
The launch of so many commercial electric vehicles shows the effort toward pollution reduction and curtailing greenhouse gas emissions. A design for an electric vehicle does not just requires the electrical system to be efficient in particular; but it is required to perform in all extreme cases of thermal and mechanical stresses. And it is made possible by all the research and development in all the areas of electrical machines, power electronics and energy storage that electric vehicle systems can meet very challenging specifications. With the availability of reliable simulation tools, a lot of time and money can be saved in the designing process. Accurate simulation tools tends to be more time consuming. There are simplification methods that save time, but at the cost of some fidelity. Moreover, design is an iterative process and optimization of design based on some specific requirement multiplies the amount of computation and hence time consumption. This thesis deals with the design and optimization of permanent magnet based traction motors with given dimensions and drive constraints. The goal is to develop a method which has the accuracy of finite element method but with much smaller time consumption for designing and optimizing the motor. Since it is a traction motor, the optimization is carried for a specific load pattern of driving a car, called a drive cycle. The program developed is tested on various types of permanent magnet motors to verify the generality of the program. For the motor topologies that cannot achieve a particular specifications, the program specifies the maximum capability of the motor.
by Krishan Kant.
S.M.
S.M. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
21
Li, You. „Design of low-capacitance and high-speed electrostatic discharge (ESD) devices for low-voltage protection applications“. Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4551.
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Electrostatic discharge (ESD) is defined as the transfer of charge between bodies at different potentials. The electrostatic discharge induced integrated circuit damages occur throughout the whole life of a product from the manufacturing, testing, shipping, handing, to end user operating stages. This is particularly true as microelectronics technology continues shrink to nano-metric dimensions. The ESD related failures is a major IC reliability concern and results in a loss of millions dollars to the semiconductor industry each year. Several ESD stress models and test methods have been developed to reproduce the real world ESD discharge events and quantify the sensitivity of ESD protection structures. The basic ESD models are: Human body model (HBM), Machine model (MM), and Charged device model (CDM). To avoid or reduce the IC failure due to ESD, the on-chip ESD protection structures and schemes have been implemented to discharge ESD current and clamp overstress voltage under different ESD stress events. Because of its simple structure and good performance, the junction diode is widely used in on-chip ESD protection applications. This is particularly true for ESD protection of low-voltage ICs where a relatively low trigger voltage for the ESD protection device is required. However, when the diode operates under the ESD stress, its current density and temperature are far beyond the normal conditions and the device is in danger of being damaged. For the design of effective ESD protection solution, the ESD robustness and low parasitic capacitance are two major concerns. The ESD robustness is usually defined after the failure current It2 and on-state resistance Ron. The transmission line pulsing (TLP) measurement is a very effective tool for evaluating the ESD robustness of a circuit or single element. This is particularly helpful in characterizing the effect of HBM stress where the ESD-induced damages are more likely due to thermal failures.; The recent industry data indicates the charged device model (CDM) ESD event becomes increasingly important in today's manufacturing environment and packaging technology. This event generates highly destructive pulses with a very short rise time and very small duration. TLP has been modified to probe CDM ESD protection effectiveness. The pulse width was reduced to the range of 1-10 ns to mimic the very fast transient of the CDM pulses. Such a very fast TLP (VFTLP) testing has been used frequently for CDM ESD characterization. The overshoot voltage and turn-on time are two key considerations for designing the CDM ESD protection devices. A relatively high overshoot voltage can cause failure of the protection devices as well as the protected devices, and a relatively long turn-on time may not switch on the protection device fast enough to effectively protect the core circuit against the CDM stress. The overshoot voltage and turn-on time of an ESD protection device can be observed and extracted from the voltage versus time waveforms measured from the VFTLP testing. Transient behaviors of polysilicon-bound diodes subject to pulses generated by the VFTLP tester are characterized for fast ESD events such as the charged device model. The effects of changing devices' dimension parameters on the transient behaviors and on the overshoot voltage and turn-on time are studied. The correlation between the diode failure and poly-gate configuration under the VFTLP stress is also investigated. Silicon-controlled rectifier (SCR) is another widely used ESD device for protecting the I/O pins and power supply rails of integrated circuits. Multiple fingers are often needed to achieve optimal ESD protection performance, but the uniformity of finger triggering and current flow is always a concern for multi-finger SCR devices operating under the post-snapback region.; Two types of diodes with different anode/cathode isolation technologies will be investigated for their ESD performance: one with a LOCOS (Local Oxidation of Silicon) oxide isolation called the LOCOS-bound diode, the other with a polysilicon gate isolation called the polysilicon-bound diode. We first examine the ESD performance of the LOCOS-bound diode. The effects of different diode geometries, metal connection patterns, dimensions and junction configurations on the ESD robustness and parasitic capacitance are investigated experimentally. The devices considered are N+/P-well junction LOCOS-bound diodes having different device widths, lengths and finger numbers, but the approach applies generally to the P+/N-well junction diode as well. The results provide useful insights into optimizing the diode for robust HBM ESD protection applications. Then, the current carrying and voltage clamping capabilities of LOCOS- and polysilicon-bound diodes are compared and investigated based on both TCAD simulation and experimental results. Comparison of these capabilities leads to the conclusion that the polysilicon-bound diode is more suited for ESD protection applications due to its higher performance. The effects of polysilicon-bound diode's design parameters, including the device width, anode/cathode length, finger number, poly-gate length, terminal connection and metal topology, on the ESD robustness are studied. Two figures of merits, FOM_It2 and FOM_Ron, are developed to better assess the effects of different parameters on polysilicon-bound diode's overall ESD performance. As latest generation package styles such as mBGAs, SOTs, SC70s, and CSPs are going to the millimeter-range dimensions, they are often effectively too small for people to handle with fingers.; Without a proper understanding of the finger turn-on mechanism, design and realization of robust SCRs for ESD protection applications are not possible. Two two-finger SCRs with different combinations of anode/cathode regions are considered, and their finger turn-on uniformities are analyzed based on the I-V characteristics obtained from the transmission line pulsing (TLP) tester. The dV/dt effect of pulses with different rise times on the finger turn-on behavior of the SCRs are also investigated experimentally. In this work, unless noted otherwise, all the measurements are conducted using the Barth 4002 transmission line pulsing (TLP) and Barth 4012 very-fast transmission line pulsing (VFTLP) testers.ID: 029050342; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references (p. 92-100).
Ph.D.
Doctorate
Department of Electrical Engineering and Computer Science
Engineering and Computer Science
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Spinks, Stephen James. „Fault simulation for structural testing of analogue integrated circuits“. Thesis, University of Hull, 1998. http://hydra.hull.ac.uk/resources/hull:8047.
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In this thesis the ANTICS analogue fault simulation software is described which provides a statistical approach to fault simulation for accurate analogue IC test evaluation. The traditional figure of fault coverage is replaced by the average probability of fault detection. This is later refined by considering the probability of fault occurrence to generate a more realistic, weighted test metric. Two techniques to reduce the fault simulation time are described, both of which show large reductions in simulation time with little loss of accuracy. The final section of the thesis presents an accurate comparison of three test techniques and an evaluation of dynamic supply current monitoring. An increase in fault detection for dynamic supply current monitoring is obtained by removing the DC component of the supply current prior to measurement.
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Bowlin, Oscar E. „Modeling and simulation of the free electron laser and railgun on an electric Naval surface platform“. Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Mar%5FBowlin.pdf.
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Legesse, Michael. „Coupled simulation of an indirect field oriented controlled induction motor drive“. Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=116014.
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Conventionally, system simulations of induction motor drives use lumped parameters model of the motor. This approach assumes motor parameters to be constant during the entire operation of the drive. Unfortunately, these are known to vary significantly over the operating range of the motor due to factors such as magnetic saturation, skin effects, and operating temperature. The variations in motor parameters affect motor output and control parameters resulting in degraded drive performance. One way of overcoming this problem is by coupling the field model of the induction motor with the drive simulation. By replacing the lumped parameters model with the field model, the influence of different operating conditions on motor parameters can be taken into account dynamically. In this thesis such an approach is investigated by coupling the finite element analysis of an induction motor with the system simulation of the field oriented controlled drive. The results obtained for the coupled simulation are promising and possible future works to make this method of simulation more accurate and reliable are recommended.
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Tevi, Tete. „Enhancement of Supercapacitor Energy Storage by Leakage Reduction and Electrode Modification“. Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6148.
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Supercapacitors have emerged in recent years as a promising energy storage technology. The main mechanism of energy storage is based on electrostatic separation of charges in a region at the electrode-electrolyte interface called double layer. Various electrode materials including carbon and conducting polymers have been used in supercapacitors. Also, supercapacitors offer high life cycle and high power density among electrochemical energy storage devices. Despite their interesting features, supercapacitors present some disadvantages that limit their competitivity with other storage devices in some applications. One of those drawbacks is high self-discharge or leakage. The leakage occurs when electrons cross the double layer to be involved in electrochemical reactions in the supercapacitor’s electrolyte. In this work, the first research project demonstrates that the addition of a very thin blocking layer to a supercapacitor electrode, can improve the energy storage capability of the device by reducing the leakage. However, the downside of adding a blocking layer is the reduction of the capacitance. A second project developed a mathematical model to study how the thickness of the blocking layer affects the capacitance and the energy density. The model combines electrochemical and quantum mechanical effects on the electrons transfer responsible of the leakage. Based on the model, a computational code is developed to simulate and study the self-discharge and the energy loss in hypothetical devices with different thicknesses of the blocking layer. The third research project identified the optimal amount of a surfactant (Triton-X 100) that had a significant effect on the double layer capacitance and conductivity of a spin-coated PEDOT:PSS (poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate)) electrode. The effect of the concentration of the surfactant was investigated by measuring the electrochemical properties and the conductivity of different electrodes. The electrodes were fabricated with different concentrations of the surfactant. Scanning electron microscopy characterizations confirmed the structural change in the PEDOT:PSS that contributed to the capacitance and conductivity enhancement. A final research project proposed an approach on how to utilize the modified PEDOT:PSS added to different photoactive dyes to design a photoactive supercapacitor. The new approach showed the possibility of using a supercapacitor device as an energy harvesting as well as a storage device.
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Setréus, Johan. „Development of a Simulation Module for the Reliability Computer Program RADPOW“. Thesis, KTH, School of Electrical Engineering (EES), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4119.
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Detta examensarbete beskriver hur en Monte Carlo simulering (MCS) kan användas för tillförlitlighetsanalys av ett eldistributionssystem. Metoden har implementerats i verktyget RADPOW som nu kan utföra både analytiska och numeriska beräkningar. Angreppssättet för att utveckla denna MCS metod i RADPOW innefattade följande aktiviteter:
• Vidareutvecklade av RADPOW med införandet av ett grafiskt användargränssnitt för Windows.
• Utveckling och implementering av en iterativ analytisk metod för känslighetsanalys av eldistributionssystem i RADPOW.
• Utveckling och implementering av MCS metoden i RADPOW, vilken placerades i en fristående modul kallad Sim.
Den implementerade MCS metoden har validerats i en jämförande studie innefattande två testsystem med datorprogrammet NEPLAN. Resultat från denna studie visar att MCS metoden ger samma resultat som den analytiska metoden i RADPOW och det kommersiella verktyget NEPLAN.
This master thesis describes an implementation of a Monte Carlo Simulation (MCS) method for reliability assessment of electrical distribution systems. The method has been implemented in the reliability assessment tool RADPOW which now is able to perform both analytical and simulation evaluations. The main contributions within this thesis includes the following activities;
• Further development of RADPOW by the introducing of a graphical user interface for Windows.
• Development and implementation of an analytical sensitivity analysis routine for RADPOW.
• Development and implementation of a sequential MCS method in RADPOW in a stand alone module referred to as Sim.
The implemented MCS method has been validated in a comparable study for two case systems by a commercial software NEPLAN. Results shows that the implemented MCS method provides the same results as the analytical method in RADPOW and the NEPLAN software.
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Mehta, Shilpa D. „A circuit model BOSS simulation of nonlinear effects in long distance fiber optic systems“. Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-07112009-040230/.
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Yen, Wen-Tsung. „Comparison of SPICE and Network C simulation models using the CAM system“. PDXScholar, 1991. https://pdxscholar.library.pdx.edu/open_access_etds/4243.
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The performance of SPICE and Network C (NC) circuit simulator when simulating MOS transistor circuits has been investigated and compared. SPICE analog model, NC analog model and NC MOS_PWL model are the three MOS transistor models being used. The comparison between SPICE and NC includes five areas. They are MOS transistor model, circuit analysis and computational methods, limitation on the ability to simulate circuits containing the MOS transistor diode configuration, run time and the ability to build new circuit component models using derived equations.
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Shi, Benyun. „Computational methods and mechanisms for evaluating and enhancing the robustness of energy distribution systems“. HKBU Institutional Repository, 2012. https://repository.hkbu.edu.hk/etd_ra/1408.
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Fridlund, Joakim, und Oliver Wilén. „Parameter Guidelines for Electric Vehicle Route Planning“. Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279555.
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There is an urgent need to migrate the vehicle industry from conventional combustion vehicles to electric vehicles due to pressing climate changes caused by the fossil fuel industry. The general public seem to have a prejudice against electric vehicles due to their limited range and the extra planning that may be required from the user. The market for electric vehicles is much more limited than for conventional vehicles, partially because it is a much younger industry. Buying an electric vehicle is also a bigger change than just buying a new car, one has to plan and manage the limited range in a new way. Unfortunately, it is more complicated to create a route planner for electric vehicles than for conventional vehicles and the market for such planners is limited. The complication is because an optimal route is better calculated by lowest energy consumption, rather than the shortest path. This requires more parameters in the routing algorithm to accurately calculate the energy consumption for individual vehicles. The problem attended to in this thesis is that no clear guidelines exist about which parameter affect the energy consumption in an electric vehicle and to what degree. The purpose of this thesis is to provide guidelines that can show which of nine chosen parameters to implement in an electric vehicle route planner. The parameters chosen in this thesis are already implemented in Simulation of Urban Mobility, a road traffic simulator. The simulator is used in this thesis to simulate electric vehicles with different parameter values and analyse the impact they have on the energy consumption when the values are incremented. The thesis shows that although some parameters have a relatively large impact on the energy consumption, it is hard to approximate the correct values for them, and therefore not worth implementing.Det finns ett brådskande behov att migrera bilindustrin från fossildrivna bilar till eldrivna bilar på grund av den rådande klimatpåverkan av fossila bränslen. Allmänheten verkar ha fördomar mot elbilar på grund av deras begränsade räckvidd och den ytterligare planering som krävs av en elbilsanvändare. Marknaden för elbilar är mer begränsad än marknaden för fossildrivna bilar. Delvis för att elbilsmarknaden är en mycket yngre industri men också för att köpa elbil är en större förändring än att köpa en vanlig bil. En elbilsförare måste använda bilen på ett annorlunda sätt på grund av den kortare räckvidden. Dessvärre så är det mer komplicerat att skapa en ruttplanerare för elbilar än för fossildrivna bilar, och marknaden för sådana ruttplanerare är begränsad. Problemet är att en optimal rutt för en elbil är beräknas mer effektivt med hjälp av lägsta energikonsumtionen istället för den kortaste vägen. Detta kräver mer parametrar i algoritmen för ruttplanering för att effektivt beräkna energikonsumtionen för individuella fordon. Problemet som hanteras i denna rapport är att det inte finns några tydliga riktlinjer om vilka parametrar som har störst påverkan på energikonsumtionen i en elbil. Syftet med denna rapport är att förse riktlinjer som visar vilka av nio valda parametrarna som är värda att implementera i en ruttplanerare för elbilar. Parametrarna som valdes är implementerade i trafiksimulatorn Simulation of Urban Mobility. Trafiksimulatorn används för att simulera elbilar och analysera förändringen i energikonsumtionen när parametervärdena stegvis ökas. Rapporten visar att även om vissa parametrar har en relativt stor påverkan på energikonsumtionen så är det svårt att uppskatta de korrekta värdena för dem. Dessa parametrar är därför inte värda att implementera.
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Nguyen, Duy Huu Manh. „Analysing electricity markets with evolutionary computation“. University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2002. http://theses.library.uwa.edu.au/adt-WU2003.0018.
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The use of electricity in 21st century living has been firmly established throughout most of the world, correspondingly the infrastructure for production and delivery of electricity to consumers has matured and stabilised. However, due to recent technical and environmental–political developments, the electricity infrastructure worldwide is undergoing major restructuring. The forces driving this reorganisation are a complex interplay of technical, environmental, economic and political factors. The general trend of the reorganisation is a dis–aggregation of the previously integrated functions of generation, transmission and distribution, together with the establishment of competitive markets, primarily in generation, to replace previous regulated monopolistic utilities. To ensure reliable and cost effective electricity supply to consumers it is necessary to have an accurate picture of the expected generation in terms of the spatial and temporal distribution of prices and volumes. Previously this information was obtained by the regulated utility using technical studies such as centrally planned unit–commitment and economic–dispatch. However, in the new deregulated market environment such studies have diminished applicability and limited accuracy since generation assets are generally autonomous and subject to market forces. With generation outcomes governed by market mechanisms, to have an accurate picture of expected generation in the new electricity supply industry, it is necessary to complement traditional studies with new studies of market equilibrium and stability. Models and solution methods have been developed and refined for many markets, however they cannot be directly applied to the generation market due to the unique nature of electricity, having high inelastic demand, low storage capability and distinct transportation requirements. Intensive effort is underway to formulate solutions and models that specifically reflect the unique characteristics of the generation market. Various models have been proposed including game theory, stochastic and agent–based systems. Similarly there is a diverse range of solution methods including, Monte–Carlo simulations, linear–complimentary and quadratic programming. These approaches have varying degrees of generality, robustness and accuracy, some being better in certain aspects but weaker in others. This thesis formulates a new general model for the generation market based on the Cournot game, it makes no conjectures about producers’ behaviour and assumes that all electricity produced is immediately consumed. The new formulation characterises producers purely by their cost curves, which is only required to be piece–wise differentiable, and allows consumers’ characteristics to remain unspecified. The formulation can determine dynamic equilibrium and multiple equilibria of markets with single and multiple consumers and producers. Additionally stability concepts for the new market equilibrium is also developed to provide discrimination for dynamic equilibrium and to enable the structural stability of the market to be assessed. Solutions of the new formulation are evaluated by the use of evolutionary computation, which is a guided stochastic search paradigm that mimics the operation of biological evolution to iteratively produce a population of solutions. Evolutionary computation is employed as it is adept at finding multiple solutions for underconstrained systems, such as that of the new market formulation. Various enhancements to significantly improve the performance of the algorithms and simplify its application are developed. The concept of convergence potential of a population is introduced together with a system for the controlled extraction of such potential to accelerate the algorithm’s convergence and improve its accuracy and robustness. A new constraint handling technique for linear constraints that preserves the solution’s diversity is also presented together with a coevolutionary solution method for the multiple consumers and producers market. To illustrate the new electricity market formulation and its evolutionary computation solution methods, the equilibrium and stability of a test market with one consumer and thirteen thermal generators with valve point losses is examined. The case of a multiple consumer market is not simulated, though the formulation and solution methods for this case is included. The market solutions obtained not only confirms previous findings thus validating the new approach, but also includes new results yet to be verified by future studies. Techniques for market designers, regulators and other system planners in utilising the new market solutions are also given. In summary, the market formulation and solution method developed shows great promise in determining expected generation in a deregulated environment.
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Narasimha, Raju Divya. „Study of ESD effects on RF power amplifiers“. Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4993.
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Today, ESD is a major consideration in the design and manufacture of ICs. ESD problems are increasing in the electronics industry because of the increasing trend toward higher speed and smaller device sizes. There is growing interest in knowing the effects of ESD protection circuit on the performance of semiconductor integrated circuits (ICs) because of the impact it has on core RF circuit performance. This study investigated the impact of ESD protection circuit on RF Power amplifiers. Even though ESD protection for digital circuits has been known for a while, RF-ESD is a challenge. From a thorough literature search on prior art ESD protection circuits, Silicon controlled rectifier was found to be most effective and reliable ESD protection for power amplifier circuit. A SCR based ESD protection was used to protect the power amplifier and a model was developed to gain better understanding of ESD protected power amplifiers. Simulated results were compared and contrasted against theoretically derived equations. A 5.2GHz fully ESD protected Class AB power amplifier was designed and simulated using TSMC 0.18 micrometer] technology. Further, the ESD protection circuit was added to a cascoded Class-E power amplifier operating at 5.2 GHz. ADS simulation results were used to analyze the PA's RF performance degradation. Various optimization techniques were used to improve the RF circuit performance.ID: 029809372; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.)--University of Central Florida, 2011.; Includes bibliographical references.
M.S.
Masters
Electrical Engineering and Computer Science
Engineering and Computer Science
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Malobabic, Slavica. „Transient Safe Operating Area (TSOA) for ESD applications“. Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5420.
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A methodology to obtain design guidelines for gate oxide input pin protection and high voltage output pin protection in Electrostatic Discharge (ESD) time frame is developed through measurements and Technology Computer Aided Design (TCAD). A set of parameters based on transient measurements are used to define Transient Safe Operating Area (TSOA). The parameters are then used to assess effectiveness of protection devices for output and input pins. The methodology for input pins includes establishing ESD design targets under Charged Device Model (CDM) type stress in low voltage MOS inputs. The methodology for output pins includes defining ESD design targets under Human Metal Model (HMM) type stress in high voltage Laterally Diffused MOS (LDMOS) outputs. First, the assessment of standalone LDMOS robustness is performed, followed by establishment of protection design guidelines. Secondly, standalone clamp HMM robustness is evaluated and a prediction methodology for HMM type stress is developed based on standardized testing. Finally, LDMOS and protection clamp parallel protection conditions are identified.ID: 031001296; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Adviser: Juin J. Liou.; Title from PDF title page (viewed March 7, 2013).; Thesis (Ph.D.)--University of Central Florida, 2012.; Includes bibliographical references (p. 252-262).
Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
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Chaillout, J. J. „De la simulation .... .... à la récupération“. Habilitation à diriger des recherches, Université de Grenoble, 2007. http://tel.archives-ouvertes.fr/tel-00614924.
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Le " Chapitre II : De la simulation...." résume ma connaissance des principales méthodes numériques utilisées en électromagnétisme. Suit ensuite le résumé de mes études les plus représentatives dans le domaine de la simulation numérique en électromagnétisme : une en statique, une en quasi-statique avec couplage faible et une en propagation d'ondes. Souvent seule la méthode appliquée à des cas test est présentée, car leurs niveaux de confidentialité empêchent d'en présenter les résultats quantifiés. Le " Chapitre III :.... À la récuperation " contient tout d'abord un état de l'art de la récupération d'énergie permettant de comparer les performances des différents couples sources/conversion. Pour cela, j'insiste particulièrement sur tous les facteurs à prendre en compte pour choisir le couple optimal dans un environnement donné. Ensuite, on y trouve le résumé des deux thèses et d'un DRT que j'ai co-encadrés dans le domaine. Le " Chapitre IV : perspectives " présente les évolutions de ma carrière scientifique dans les deux axes développés dans ce rapport. Pour les évolutions souhaitables des méthodes numériques de manière générale et plus particulièrement dans mon Département, j'en expose ma vision et comment je prévois d'y contribuer. Pour l'axe énergétique, je présente les travaux prévus afin de conforter nos succès récents ainsi que les collaborations en cours ou amorcées.
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Stefopoulos, Georgios Konstantinos. „Quadratic power system modeling and simulation with application to voltage recovery and optimal allocation of VAr support“. Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29695.
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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010.Committee Chair: Meliopoulos, A. P. Sakis; Committee Member: Deng, Shijie; Committee Member: Divan, Deepakraj; Committee Member: Harley, Ronald; Committee Member: Taylor, David. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Ellis, Mikle Val. „The ladder load-flow method extended to distribution networks“. Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/39138.
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The rigorous load-flow analysis of Distribution Networks requires the modeling of mutual coupling, multiphase possibilities and unbalanced loading. The Ladder Load-Flow Method meets these requirements, but is limited to radial systems. The Switch Compensation Method presented here, extends the Ladder Load-Flow Method to solve Distribution Networks. A network analysis program has been developed using the Electric Power Research Distribution Engineering Workstation (DEWorkstation). The program uses the pointers provided by the DEWorkstation to represent the connectivity of the system. The use of these pointers increases the speed of execution while naturally handling the sparsity of the system. The user is also provided with "on line" attribute and topological data maintenance. The extension technique is based on Thevenin's Theorem. This approach allows the accurate determination of the equivalent impedance for networks which contain series and shunt elements. The equivalent impedance can be changed during the iterative solution process. This allows the algorithm to simulate the operation of control devices which significantly alter the impedance of the network. A transformer model for the forward and reverse trace of the Ladder Method is also presented.Ph. D.
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Skowronn, Dietmar Reinhard. „Simulation of Switched Linear Networks“. PDXScholar, 1993. https://pdxscholar.library.pdx.edu/open_access_etds/4644.
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This thesis deals with the time-domain analysis of switched linear networks and investigates inherent problems which have to be considered when analyzing this class of networks. Computer simulation requires the use of numerical methods and we focus on the transmission -line modelling technique (TLM) and the numerical inverse Laplace transform. A general approach based on the one-graph modified nodal description is given which allows the formulation of circuit equations of a TLM-modelled circuit by inspection. The numerical equivalence of TLM and trapezoidal rule has been found and a proof is given. A variable step size simulator has been developed based on the 4th order numerical inverse Laplace transform. The properties of this method are reviewed and its limitations are discussed. Simulation results are given to illustrate capabilities of the simulator.
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Tiew, Chin-Yaw. „On improving the performance of parallel fault simulation for synchronous sequential circuits“. Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-03042009-040323/.
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Wirnsberger, Peter. „Computer simulation and theoretical prediction of thermally induced polarisation“. Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/282988.
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In this thesis, we study the phenomenon of thermally induced polarisation using a combination of theory and computer simulation. Molecules of sufficiently low symmetry exhibit thermo-molecular orientation when subjected to a temperature gradient, leading to considerable electrostatic fields in polar liquids. Here, we first use non-equilibrium molecular dynamics simulations to study this interesting effect numerically. To this end, we propose an integration algorithm to impose a constant heat flux in simulations and show that it greatly improves energy conservation compared to a previous algorithm. We next investigate the thermal polarisation of water and find that truncation of electrostatic interactions can lead to severe artefacts, such as the wrong sign of polarisation and an overestimation of the electric field. We further show that the quadrupole-moment contribution to the electric field is significant and responsible for an inversion of its sign. To facilitate the theoretical description of electrostatic interactions, we propose a new dipolar model fluid as a perturbation of a Stockmayer fluid. Using this modified Stockmayer model, we provide numerical evidence for the recently proposed phenomenon of thermally induced monopoles. We show that the electrostatic field generated by a pair of heated/cooled colloidal particles immersed in such a solvent can be trivially described by two Coulomb charges. Finally, we propose a mean-field theory to predict the thermo-polarisation effect exhibited by our model fluid theoretically, and demonstrate near quantitative agreement with simulation results.
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Lee, Hyung Ki. „Fault simulation and test pattern generation for synchronous and asynchronous sequential circuits“. Diss., This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06062008-171759/.
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Aminou, Moussavou Anges Akim. „Modelling and analysis of microgrid control techniques for grid stabilisation“. Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/1184.
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Thesis submitted in fulfilment of the requirements for the degree
Master of Technology: Electrical Engineering
in the Faculty of Engineering
at the
Cape Peninsula University of Technology
2014In recent times, renewable energy-based distributed generation (DG) has captivated the industrial sector and on a global scale this has become a leading research area. Distributed generation using wind, solar energy or biomass as a source of energy can produce electricity on a small scale. Therefore, there is a strong focus on using renewable energy as a safe alternative source of energy, especially because it can in future play a dominant role in the world’s energy production and help to tackle the increase of global warming caused by fossil energy. However, a major problem facing renewable energies is that they are highly dependent on weather conditions. Since the power generated by DG, as well as consumption, depends on the weather conditions, irregularity of production and consumption leads to frequency and voltage fluctuations, and it can become difficult to determine and monitor consumer usage at any given time. Distributed generation can then be subjected to discrepancies in consumer usage and this can lead to severe overloading. As a result, microgrids powered by DG, operating in a single, stand-alone controllable system mode, face new challenges in terms of balancing a cluster of loads. Balancing a cluster of loads by making sure at all times that the entire system operates without overloading, is an essential requirement for the proper operation of a power system. The microgrid load considered in this project is the sum of sensitive and non-sensitive loads, respectively 5 kW and 100 kW, which constitute load requirement of one village; this total load required by a number of villages is called a cluster load. Depending on the input power generated by a DG-based photovoltaic (PV) system, these loads can be controlled using a logic control switch (LCS). When the power produced is less than the minimum load required by a component of a cluster, overloading occurs. The purpose of using an LCS is to ensure that a stable system is maintained under various loads and resource conditions. An LCS is used to continuously monitor and adjust load through circuit breakers. It is a good alternative to load balancing for a cluster of villages in rural area where a microgrid is operating in stand-alone mode. The focus of this research is to design a photovoltaic system with a maximum capacity of 1 MW providing power to a cluster of rural villages, and operating in stand-alone mode, and then to apply different control techniques (droop control, dq0 reference frame + proportional integral (PI) controller, and PI controller alone) at the inverter terminal of the PV system, in order to evaluate the stability of the output voltage. Another goal of the research is to develop an energy management system (EMS) algorithm to support the PV system in reducing loads. Therefore, a iii stable system under various load and resource conditions, as well as suitable control mechanisms are required to model a PV system. There is a need for the modelling of a PV array using a physical modelling block in MATLAB (SIMULINK) software. The state flow provided by SIMULINK is used in this project to develop an algorithm for load balancing. The state flow gives possibilities of modelling complex algorithms by combining graphical and tabular representations to create sequential decision logic, derived from state transition diagrams and tables, flow charts and truth tables. Furthermore, the design of a microgrid using photovoltaic DG and an energy management system, has been developed. The present work mainly consists of a stand-alone microgrid operation, where the power generated must be equal to the load power. In addition, different control methods, consisting of a dq0 reference frame + PI controller, are analysed at the invertor terminal. Subsequently an LCS algorithm is developed; this is required to maintain the system within certain limits and prevents overloading. LCS algorithms are based on a flowchart and allow switching automatically selected loads, depending on the power (solar radiation) available. In addition, a flow chart provides an easy way of using a graphical transition state and state chart to establish a set of rules for the system. The simulation results show that both droop control and a dq0 reference frame + PI controller are much better than a PI controller alone; these results also compared well with similar studies found in the literature. Also, these results are further improved with an EMS in order to maintain the output voltage of the microgrid, by switching on and off certain loads depending on the input power. The modelling of the microgrid using DG, based on photovoltaic systems with a maximum capacity of 1 MW, supports and improves the PV system by reducing loads. Moreover, droop control, and dq0 transformation + PI control present a better result than PI controller alone.
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Conradie, Antonie Eduard. „Performance optimization of engineering systems with particular reference to dry-cooled power plants“. Thesis, Link to the online version, 1995. http://hdl.handle.net/10019.1/1326.
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Fahey, Mark, und n/a. „Assessment of the suitability of CFD for product design by analysing complex flows around a domestic oven“. University of Otago. Department of Design Studies, 2007. http://adt.otago.ac.nz./public/adt-NZDU20070417.111809.
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Competitive global markets are increasing the commercial pressure on manufacturing companies to develop better products in less time. To meet these demands, the appliance manufacturer, Fisher & Paykel, has considered the use of computer simulation of fluid flows to assist in product design. This technology, known as Computational Fluid Dynamics (CFD), has the potential to provide rewarding insight into the behaviour of designs involving fluids. However, the investment in CFD is not without risk. This thesis investigates the use of CFD in oven design expressly to evaluate the numerical accuracy and suitability of CFD in the context of oven product development.
CFD was applied to four cases related to oven design, along with detailed experimental investigations, and resulted in a number of relevant findings. In a study of an impinging jet, the SST turbulence model was found to produce better results than the k-ε turbulence model. Measurements indicated that the flow was unsteady, but CFD struggled to reproduce this behaviour. The synergy between experimental and numerical techniques was highlighted in the simulation of a two-pane oven door, and resulted in temperatures on outer surface of the door predicted by CFD to within 2% of measured values. In the third study, a CFD simulation of a tangential fan failed to deliver acceptable steady-state results, however a transient simulation showed promise. The final case examined the flows through the door and cooling circuit of the Titan oven. Velocities predicted by CFD compared well against measurements in some regions, such as the potential core of the jet at the outlet vent, but other regions, such as entrained air, were poor. Temperatures were predicted to within an average of 2% of measured values.
It is found that limited accuracy does not necessarily prevent CFD from delivering engineering value to the product development process. The engineering value delivered by CFD is instead more likely to be limited by the abilities of the user. Incompatibilities between CFD and the product development process can reduce the potential value of CFD but the effects can be minimised by appropriate management action. The benefits of CFD are therefore found to be sufficient to merit its use in the product development process, provided its integration into the organisation is managed effectively and the tool is used with discernment. Recommendations for achieving this are provided.
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Luwaca, Emmanuel. „Virtualization of a sensor node to enable the simulation of IEC 61850-based sampled value messages“. Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/1179.
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Thesis submitted in fulfilment of the requirements for the degree
Master of Technology: Electrical Engineering
in the Faculty of Engineering
at the Cape Peninsula University of Technology
2014The IEC 61850 standard, “Communication networks and systems in substations” was promulgated to accommodate the need for a common communication platform within substations for devices from different vendors. The IEC 61850 standard proposes a substation automation architecture that is Ethernet-based, with a “station-bus” for protection devices within the substation and a “process bus” where raw data from the voltage and current transformers are published onto the data network using a device known as a Merging Unit. To date, most of the standardization efforts were focused at the station bus level where event-triggered messages are exchanged between the substation automation devices, commonly referred to as Intelligent Electronic Devices (IEDs). These messages are known as Generic Object Oriented Substation Event messages. Equipment from vendors to accommodate the “process bus” paradigm, however is still limited at present. The Centre for Substation Automation and Energy Management Systems was established within the Electrical Engineering Department at the Cape Peninsula University of Technology with one of its objectives being the development of equipment either for simulation or real-time purposes in compliance with the IEC 61850 standard. In order to fulfil this long-term objective of the Centre, an in-depth understanding of the IEC 61850 standard is required. This document details the efforts at acquiring the requisite knowledge base in support of the educational objectives of the Centre and the research project implements a simulation of a merging unit which is compliant with the functional behavior as stipulated by the standard. This limited functional implementation (i.e. non-real-time) of the merging unit, is achieved through the development of a virtualized data acquisition node capable of synthetic generation of waveforms, encoding of the data and publishing the data in a format compliant with the IEC 61850-9-2 sampled value message structure. This functional behavior of the virtual sensor node which was implemented has been validated against the behavior of a commercial device and the sampled value message structure is validated against the standard. The temporal behavior of the proposed device is commented upon. This research project forms the basis for future real-time implementation of a merging unit.
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Lee, Chong Kyong 1973. „Continuation methods for steady state analysis of oscillators“. Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99777.
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Oscillator circuits are an integral component of wireless communications systems and are increasingly in demand. As such systems gain widespread use, price becomes a very important factor in the design process, and the design cycle must be optimized. This puts an increasing emphasis on the proficiency of oscillator design automation tools. At the same time, as the performance requirements of such systems are becoming more stringent, the required simulation complexity is also increasing. More specifically, high frequency selectivity and low phase noise require very high quality factor oscillators, which in turn negatively affect the convergence performance of current simulation techniques. This thesis proposes a new continuation method for improving the convergence of oscillator simulations and compares this method to some of the methods reported in the literature. The proposed approach does not require a very good initial guess in order to converge to a final solution.
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Pinchuk, Amy Ruth. „Spectrally correct finite element analysis of electromagnetic fields“. Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75780.
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Direct solution for three dimensional electric or magnetic field vectors throughout the frequency spectrum is accomplished by a finite element formulation which includes displacement and conduction currents, and requires no special treatment for material interfaces. Analysis of bus bar and Bath cube eddy current problems demonstrate the capabilities of the method.Spurious components in solutions to vector field problems are shown to corrupt deterministic solutions. These corruptions are identifiable with spurious modes familiar to high frequency modal analysis. Spectrally correct mixed order finite elements are demonstrated to retrieve accuracy in deterministic analyses.
The formulation may be limited by computer round-off at matrix assembly which affects the solenoidality of vector fields. Furthermore, extreme values encountered in low frequency eddy current analysis lead to ill conditioning and unreliable solutions. These numerical instabilities are overcome by parametric adjustment of permittivities. Error estimates are established to monitor inaccuracies introduced by permittivity adjustment.
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Liu, Kai, und 劉愷. „Optimal dispatch and management for smart power grid“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46336680.
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Ng, Kwok-kei Simon, und 吳國基. „Optimal planning and management of stochastic demand and renewable energy in smart power grid“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B50434299.
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To combat global climate change, the reduction of carbon emissions in different industries, particularly the power industry, has been gradually moving towards a low-carbon profile to alleviate any irreversible damage to the planet and our future generations. Traditional fossil-fuel-based generation is slowly replaced by more renewable energy generation while it can be harnessed. However, renewables such as solar and wind are stochastic in nature and difficult to predict accurately. With the increasing content of renewables, there is also an increasing challenge to the planning and operation of the grid.
With the rapid deployment of smart meters and advanced metering infrastructure (AMI), an emerging approach is to schedule controllable end-use devices to improve energy efficiency. Real-time pricing signals combined with this approach can potentially deliver more economic and environmental advantages compared with the existing common flat tariffs. Motivated by this, the thesis presents an automatic and optimal load scheduling framework to help balance intermittent renewables via the demand side.
A bi-level consumer-utility optimization model is proposed to take marginal price signals and wind power into account. The impact of wind uncertainty is formulated in three different ways, namely deterministic value, scenario analysis, and cumulative distributions function, to provide a comprehensive modeling of unpredictable wind energy. To solve the problem in off-the-shelf optimization software, the proposed non-linear bi-level model is converted into an equivalent single-level mixed integer linear programming problem using the Karush-Kuhn-Tucker optimality conditions and linearization techniques. Numerical examples show that the proposed model is able to achieve the dual goals of minimizing the consumer payment as well as improving system conditions. The ultimate goal of this work is to provide a tool for utilities to consider the demand response model into their market-clearing procedure.
As high penetration of distributed renewable energy resources are most likely applied to remote or stand-alone systems, planning such systems with uncertainties in both generation and demand sides is needed. As such, a three-level probabilistic sizing methodology is developed to obtain a practical sizing result for a stand-alone photovoltaic (PV) system. The first-level consists of three modules: 1) load demand, 2) renewable resources, and 3) system components, which comprise the fundamental elements of sizing the system. The second-level consists of various models, such as a Markov chain solar radiation model and a stochastic load simulator. The third-level combines reliability indices with an annualized cost of system to form a new objective function, which can simultaneously consider both system cost and reliability based on a chronological Monte Carlo simulation and particle swamp optimization approach. The simulation results are then tested and verified in a smart grid laboratory at the University of Hong Kong to demonstrate the feasibility of the proposed model.
In summary, this thesis has developed a comprehensive framework of demand response on variable end-use consumptions with stochastic generation from renewables while optimizing both reliability and cost. Smart grid technologies, such as renewables, microgrid, storage, load signature, and demand response, have been extensively studied and interactively modeled to provide more intelligent planning and management for the smart grid.published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy
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Zhu, Qiujun. „Driving Pattern Generation for Customized Energy Control Strategy in Hybrid Electric Vehicle Applications“. University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1404726699.
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Liu, Zhiwei. „Design of silicon controlled rectifers sic] for robust electrostatic discharge protection applications“. Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4552.
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Another issue with SCR devices is its deep snapback or lower holding voltage, which normally will lead to the latch-up happen. To make SCR devices be immunity with latch-up, it is required to elevate its holding voltage to be larger than the circuits operational voltage, which can be several tens volts in modern power electronic circuits. Two possible solutions have been proposed to resolve this issue. One solution is accomplished by using a segmented emitter topology based on the concept that the holding voltage can be increased by reducing the emitter injection efficiency. Experimental data show that the new SCR can posses a holding voltage that is larger than 40V and a failure current It2 that is higher than 28mA/um. The other solution is accomplished by stacking several low triggering voltage high holding voltage SCR cells together. The TLP measurement results show that this novel SCR stacking structure has an extremely high holding voltage, very small snapback, and acceptable failure current. The High Holding Voltage Figure of Merit (HHVFOM) has been proposed to be a criterion for different high holding voltage solutions. The HHVFOM comparison of our proposed structures and the existing high holding voltage solutions also show the advantages of our work.; Electrostatic Discharge (ESD) phenomenon happens everywhere in our daily life. And it can occurs through the whole lifespan of an Integrated Circuit (IC), from the early wafer fabrication process, extending to assembly operation, and finally ending at the user's site. It has been reported that up to 35% of total IC field failures are ESD-induced, with estimated annual costs to the IC industry running to several billion dollars. The most straightforward way to avoid the ICs suffering from the threatening of ESD damages is to develop on-chip ESD protection circuits which can afford a robust, low-impedance bypassing path to divert the ESD current to the ground. There are three different types of popular ESD protection devices widely used in the industry, and they are diodes or diodes string, Grounded-gate NMOS (GGNMOS) and Silicon Controlled Rectifier (SCR). Among these different protection solutions, SCR devices have the highest ESD current conduction capability due to the conductivity modulation effect. But SCR devices also have several shortcomings such as the higher triggering point, the lower clamping voltage etc, which will become obstacles for SCR to be widely used as an ESD protection solutions in most of the industry IC products. At first, in some applications with pin voltage goes below ground or above the VDD, dual directional protection between each two pins are desired. The traditional dual-directional SCR structures will consume a larger silicon area or lead to big leakage current issue due to the happening of punch-through effect. A new and improved SCR structure for low-triggering ESD applications has been proposed in this dissertation and successfully realized in a BiCMOS process. Such a structure possesses the desirable characteristics of a dual-polarity conduction, low trigger voltage, small leakage current, large failing current, adjustable holding voltage, and compact size.ID: 029094215; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references (p. 72-78).
Ph.D.
Doctorate
School of Electrical Engineering and Computer Science
Engineering and Computer Science