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Schietekat, Louis Magnus. "Design and implementation of the main controller of a solid-state transformer." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17899.
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Thesis (MScEng)--Stellenbosch University, 2011.ENGLISH ABSTRACT: The Solid-State Transformer (SST) is presented as an alternative to the traditional Line-Frequency Transformer (LFT) used for voltage-level transformation in distribution grids. The LFT technology is highly matured which results in low costs and high efficiency. The SST however, introduces several advantages compared to the LFT, some of which are input unity power-factor, near perfect output-voltage regulation, frequency variation as well as harmonic filtering. The SST consists of three power-electronic converter stages: The input stage, the isolation stage and the output stage. The input and isolation stages are implemented with a multilevelconverter topology incorporating a converter-stack for each phase. Each stack consists of N converter building blocks, called cells. In this thesis the design and implementation of the main controller is presented. The main controller, together with N cell controllers, is responsible for the control of the cells within the respective stack. Three main controllers are thus implemented within the SST. Each cell consists of an Active Rectifier (AR) and a DC-DC Converter (DC-DC). The SST control design thus starts with the AR control which is subsequently expanded to Cascaded Active-Rectifier (CAR) control. Design is completed with the addition of the DC-DC control. Time domain simulations of the AR- and CAR-control are presented and discussed. Test measurements, verifying functionality of each control design-phase, are presented and discussed.
AFRIKAANSE OPSOMMING: Die Drywingselektroniese Transformator (DET) word voorgestel as ’n alternatief vir die Lyn Frekwensie Transformator (LFT) wat gebruik word vir spannings-vlak tranformasie op distribusie vlak. The LFT tegnologie is ver gevorderd wat ly tot hoë effektiwiteit en lae kostes. The DET bied wel voordele soos intree eenheids arbeid faktor, na aan perfecte uittree-spannings regulasie, frequensie variasie sovel as harmoniese filrteering. Die DET bestaan uit drie drywingselektroniese omsetter stadiums: Die intree-stadium, die isolasie-stadium en die uittree-stadium. The intree- en isolasie-stadiums word geïmplimenteer met ’n multivlak-omsetter topologie wat bestaan uit ’n omsetter-stapel vir elke fase. Elke stapel bestaan uit N omsetter boustene wat selle genoem word. In hierdie tesis word the ontwerp en implementasie van die hoofbeheerder voorgestel. Die hoofbeheerder, tesame met N selbeheerders, is verantwoordelik vir die beheer van elke sel in die spesifieke stapel. In die DET word daar dus drie hoofbeheerders gebruik. Elke sel bestaan uit ’n Aktiewe Gelykrigter (AG) en ’n GS-GS omsetter (GS-GS). Die DET beheerontwerp begin dus met die (AG) beheer wat daarna uitgebrei word na Kaskade Aktiewe Gelykrigter (KAG) beheer. Die beheer ontwerp word voltooi deur die byvoeging van die GSGS beheer. Tyd-gebied simulasies van die AG- en KAG-beheer word voorgelê en bespreek. Toetsmetings wat die funksionaliteit van elke beheer ontwepsfase verifeer, word voorgelê.
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Du, Toit Daniel Josias. "Predictive control of a series-input, parallel-output, back-to-back, flying-capacitor multilevel converter." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/18087.
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Thesis (MScEng (Electrical and Electronic Engineering))--Stellenbosch University, 2011.ENGLISH ABSTRACT: This thesis investigates the viability of constructing a solid-state transformer (SST) with a series-input, parallel-output connection of full-bridge, three-level ying-capacitor converters. It focusses on the active recti er front-end of the SST which is used to control the input current to be sinusoidal and in-phase with the sinusoidal input voltage. A stack of two converters are built and tested. The input current, as well as the ying capacitor voltages of the two active recti ers in the stack, are actively controlled by a nite-state model-based predictive (FS-MPC) controller. The use of multiple ying-capacitor converters poses a problem when using FS-MPC because of the large number of possible switching states to include in the prediction equations. Three FS-MPC control algorithms are proposed to attempt to overcome the problem associated with the large number of switching states. They are implemented on an FPGA digital controller. The algorithms are compared on the bases of voltage and current errors, as well as their responses to disturbances that are introduced into the system. The simulation and experimental results that are presented shows that by interleaving the control actions for the two converters, one can obtain fast and robust responses of the controlled variables. The viability of extending the interleaving control algorithm beyond two converters is also motivated.
AFRIKAANSE OPSOMMING: Hierdie tesis ondersoek die moontlikheid van volbrug, drievlak vlieënde-kapasitoromsetters wat gebruik word om 'n serie-intree, parallel-uittree drywingselektroniese transformator (DET) te bou. Dit fokus op die aktiewe gelykrigter van die DET wat gebruik word om die intreestroom te beheer om sinusvormig en in fase met die sinusvormige intreespanning te wees. 'n Stapel van twee omsetters word gebou en getoets. Die intreestroom, sowel as die vlieënde kapasitorspannings van die twee aktiewe gelykrigters in die stapel, word aktief beheer met behulp van 'n eindige-toestand, model-gebaseerde voorspellende beheerder (ET-MVB). Die gebruik van veelvuldige vlieënde-kapasitoromsetters bemoeilik die implementering van 'n ET-MVB-beheerder as gevolg van die groot aantal skakeltoestande wat in die voorspellende vergelykings in ag geneem moet word. Drie ET-MVB-algoritmes word voorgestel om te poog om die probleme, wat met die groot aantal skakeltoestande geassosieer word, te oorkom. Die algoritmes word in 'n FPGA digitale verwerker geïmplementeer. Die algoritmes word vergelyk op grond van hul stroom- en spanningsfoute, asook hul reaksie op steurings wat op die stelsel ingevoer word. Die simulasie en praktiese resultate toon dat, deur die beheeraksies vir die twee omsetters te laat oorvleuel, die gedrag van die beheerde veranderlikes vinniger en meer robuust is. Die moontlikheid om die oorvleuelende beheeraksies uit te brei tot meer as twee omsetters word ook gemotiveer.
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Du, Toit Delyno Johannes. "ATM cash management for a South African retail bank." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17977.
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Thesis (MScEng)--Stellenbosch University, 2011.ENGLISH ABSTRACT: Cash can be seen as a fast moving consumer good. Approaching cash as inventory within the ATM cash management environment of a South African retail bank, provided the opportunity to apply well known industrial engineering techniques to the financial industry. This led to the application of forecasting, inventory management, operational research and simulation methods. A forecasting model is designed to address the multiple seasonalities and calendar day effects that is prevalent in the demand for cash. Special days, e.g. paydays, lead to an increase in demand for cash. The weekday on which the special day falls will also influence the demand. The multiplicative Holt-Winters method is combined with an improvised distribution method to determine the demand for cash for the region and per ATM. Reordering points are calculated and simulated to form an understanding of the effect this will have on the ATM network. Direct replenishment and the traveling salesman problem is applied and simulated to determine the difference in using one or the other. Various simulation models are build to test the operational and financial impact when certain variables are amended. It is evident that more work is required to determine the optimal combination of variable values, i.e. forecasting frequency, aggregate forecasting or individual forecasting, reorder levels, loading levels, lead times, cash swap or cash add, and the type of transportation method. Each one of these are a science in itself and cannot be seen (calculated) in isolation from the other as a change in one can affect the overall operational efficiency and costs of the ATM network. The thesis proves that significant cost savings is possible, compared to the current set-up, when applying industrial engineering techniques to a geographical ATM network within South Africa.
AFRIKAANSE OPSOMMING: Kontant kan gesien word as vinnig bewegende verbruikersgoedere. Deur kontant te benader as voorraad binne die ATM kontant bestuur omgewing van ’n Suid Afrikaanse kleinhandelsbank, het dit die geleentheid geskep om bekende bedryfsingenieurstegnieke toe te pas in die finansiële industrie. Dit het gelei tot die toepassing van vooruitskatting, voorraadbestuur, operasionele navorsing en simulasie metodes. ’n Vooruitskattingsmodel is ontwerp om die verskeie seisoenaliteite en kalenderdae effekte wat deel uitmaak van die vraag na kontant aan te spreek. Spesiale dae, bv. betaaldae, lei tot ’n toename in die vraag na kontant. Die weeksdag waarop die spesiale dag voorkom sal ook ’n invloed hê op die vraag. Die multiplikatiewe Holt-Winters metode is gekombineer met ’n geïmproviseerde verspreidingsmetode om die vraag na kontant vir die streek en per ATM the bepaal. Bestellingsvlakke is bereken en gesimuleer om ’n prentjie te skep van die invloed wat dit op die ATM netwerk sal hê. Direkte hervulling en die handelsreisigerprobleem is toegepas en gesimuleer om die verskille te bepaal tussen die gebruik van of die een of die ander. Veskeie simulasie modelle is gebou om die operasionele en finansiële impak te toets, wanneer sekere veranderlikes aangepas word. Dit is duidelik dat meer werk nodig is om die optimale kombinasie van veranderlike waardes te bepaal, bv. vooruitskatting frekwensie, totale vooruiskatting of individuele vooruitskatting, bestellingsvlakke, leitye, kontant omruiling of kontant byvoeging, en die tipe vervoermetode. Elkeen van hierdie is ’n wetenskap op sy eie en kan nie in isolasie gesien en bereken word nie, want ’n verandering van een se waarde kan die hele operasionele doeltreffendheid en kostes van die ATM netwerk beïnvloed.
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Adabi, Firouzjaee Mohammad Ebrahim. "Advanced modeling of solid state transformer." Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/461451.
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The solid state transformer (SST) is seen as a proper replacement of the conventional iron-and-copper transformer in the future smart grid . The SST offers several benefits (e.g. enhanced power quality performance or reactive power control at both primary and secondary sides) that can be of paramount importance for the development of the smart grid .
This research focuses on the development and implementation of an advanced model of a three stage bidirectional SST in Matlab/Simulink. The goal is to obtain an realistic SST model (i.e. as close to the real SST as possible) that could duplicate the performance of a real MV/LV SST. This considered design consists of three main stages: medium voltage (MV) stage, isolation stage, and low voltage (LV) stage. When the power flows from the MV side to the LV side, the input power-frequency ac voltage is converted into a MV dc voltage by the three-phase ac/dc converter, which in such case works as rectifier. The isolation stage, which includes a high-frequency transformer (HFT) and the two corresponding MV- and LV-side converters, first converts the MV-side dc voltage into a high-frequency square-wave voltage applied to the primary of the HFT; the secondary side square-wave signal is then converted to a LV dc waveform by the LV-side converter, which also works as rectifier. Finally, the output LV-side three-phase dc/ac converter, which works as inverter, provides the output power-frequency ac waveform from the LV-side dc link.
Si-based semiconductor technologies can be used for MV applications using a multilelvel configuration. Recently, modular multilevel converter (MMC) topologies have attracted attention for high or medium voltage applications. These converters can provide an effective topology for the MV side of the SST; their main advantages are modularity and scalability: the desired voltage level can be easily achieved by a series connection of MMC sub-modules (SMs). In addition,a MMC topology can provide high power quality and efficiency with reduced size of passive filters. These features made the MMC option an attractive topology for the MV stage of the SST.
This thesis proposes a three-stage SST configuration based on MMC technology for MV converters.
* The input stage of the SST is connected to the distribution system via RL filters and its three-phase configuration uses a MMC technology. A half-bridge configuration is proposed for each SM.
* The isolation stage consists of three parts: a MV single-phase MMC, the high-frequency transformer (HFT), and a single-phase LV PWM converter.
* The LV side of the SST uses a three-phase four-leg PWM converter, with an RL impedance for filtering currents and a capacitor bank for filtering voltages.
The converters and their controller have been implemented adn tested considering models without and with semiconductor losses, while the SST model has been tested as a stand-alone device and a compnent of a distribution system.
The model has been tested under severe dynamic and unbalanced conditions. The simulation results support the choices made for any SST stage and proves that the proposed design could be a feasible choice for the future SST.El Transformador de Estado Sólido ("Solid State Transformer" por sus siglas en inglés) es visto como un reemplazo adecuado del transformador convencional en las futuras redes inteligentes (smart grids ). Este nuevo dispositivo presenta una amplia gama de prestaciones (p.e. mejora de la cualidad de suministro) que pueden ser de crucial importancia para el desarrollo de las redes inteligentes. El principal objetivo de esta tesis es que desarrollar e implantar el en Matlab/Simulink un modelo realista de estado sólido trifásico y bidireccional, que pueda duplicar el comportamiento de un transformador de estado sólido de Media-Baja tensión. El diseño considerado consiste en tres etapas: etapa en media tensión (MT), etapa intermedia, etapa en baja tensión (BT). Cuando la potencia fluye del terminal en media al terminal en baja tensión, la tensión alterna en el terminal de entrada a media tensión y frecuencia de operación 50 Hz se convierte en continua a media tensión mediante un convertidor trifásico rectificador. La etapa intermedia es un puente activo dual, que incluye un transformador de alta frecuencia y los correspondientes convertidores en media y baja tensión: primero, la media tensión continua es convertida en media tensión alterna a alta frecuencia; esta tensión es reducida a baja tensión preservando la alta frecuencia mediante el transformador, finalmente, la tensión en el terminal de salida del transformador es rectificada y convertida en baja tensión continua). La entrada en la etapa de salida en BT es, por tanto, una tensión continua que es convertida en tensión alterna a frecuencia de operación 50 Hz mediante un convertidor que funciona como inversor. Puesto que el diseño del dispositivo estudiado en esta tesis es bidireccional, en caso de que la potencia tenga que fluir desde el lado de BT al lado de MT, la función de los convertidores se invierte (es decir, los rectificadores pasan a operar como inversores, los inversores pasan a operar como rectificadores) en cualquiera de las etapas. Los actuales semiconductores solo pueden ser utilizados en aplicaciones de media y alta tensión empleando convertidores multi-nivel. Durante los últimos años ha ganado popularidad la tecnología MMC (modular multilevel converter), que permite diseñar configuraciones adecuadas para el lado de MT de un transformador de estado sólido; sus principales ventajas están en modularidad y escalabilidad: el nivel de tensión adecuado se puede conseguir mediante la conexión en serie de tantos sub-módulos como sea necesario. Además con la tecnología MMC se puede obtener una alta calidad en las ondas de tensión y corriente, así como un elevado rendimiento con tamaño reducido en los filtros de entrada. Esta tesis propone un diseño trifásico bidireccional con las siguientes características: - La etapa de entrada está conectada a una red de distribución en MT mediante filtros RL y su configuración trifásica usa convertidores de tecnología MMC. - La etapa intermedia contiene tres secciones: un convertidor monofásico en configuración MMC, un transformador de MT/BT y alta frecuencia, y un convertidor monofásico en BT. - La etapa de salida en BT usa un convertidor trifásico PWM (pulse wide modulation), con un filtro RL para las corrientes y un banco de condensadores para filtrar tensiones. Los convertidores han sido implantados en Matlab/Simulink y simulados considerando modelos con y sin pérdidas en los semiconductores, mientras que el modelo completo de transformador de estado sólido ha sido analizado considerando dos configuraciones distintas del sistema a estudiar: el transformador aislado y formando parte de una red de distribución en MT. Los modelos de transformador con y sin pérdidas han sido simulados bajo ciertas condiciones de operación. Los resultados confirman que la configuración seleccionada para cada etapa del nuevo dispositivo permite obtener un diseño fiable que puede mejorar el funcionamiento de las futuras redes inteligentes.
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Godoi, Lucas Antonio Alves de. "Transformador de estado sólido no controle de fluxo de potência em redes de distribuição." Ilha Solteira, 2018. http://hdl.handle.net/11449/154491.
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Orientador: Júlio Borges de SouzaResumo: O transformador de estado sólido tem se apresentado como uma ferramenta indispensável na construção das novas redes elétricas inteligentes, uma vez que essa nova estrutura de rede altera o layout tradicional, viabilizando a conexão de fontes de energia descentralizadas. Contudo, essa conexão de sistemas de geração distribuída na rede originou a bidirecionalidade do fluxo de potência, resultando em um novo panorama para as atividades de operação e manutenção das redes para as distribuidoras de energia. A análise dos possíveis impactos técnicos gerados na rede de distribuição deve ser realizada, com o intuito de garantir um nível de qualidade energética dentro dos padrões estabelecidos pela Agência Nacional de Energia Elétrica – ANEEL. Dentre os impactos, destacam-se a elevação do nível de tensão e a alteração do fator de potência, ambos, produzidos pelo excesso de potência injetada na rede por este novo cenário de geração de energia. Nesse contexto, esta dissertação tem como principal objetivo analisar o comportamento de uma rede de distribuição genérica com penetração de geração distribuída e avaliar o perfil de tensão diante de diferentes níveis de inserção dessa geração na rede. As características de ajuste de tensão instantânea e capacidade de interação com sistemas de armazenamento que o transformador de estado sólido possui foram empregadas no auxílio da regulação dos níveis de tensão que se apresentaram fora dos padrões determinados pela resolução 794/2018 da ANEEL, qua... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The solid state transformer has been presented as an essential tool in the construction of new intelligent electric grids, since this new network structure changes the traditional layout, making possible the connection of decentralized energy sources. However, this connection of distributed generation systems in the network created the bidirectionality of the power flow, resulting in a new panorama for the power distributors concerning the networks activities of operation and maintenance. The analysis of the possible technical impacts generated in the distribution network should be carried out with the purpose of guaranteeing a level of energy quality within the standards established by the National Electric Energy Agency (ANEEL). Among the impacts, we highlight the elevation of the voltage level and the change in the power factor, both produced by the excess power injected into the grid by this new energy generation scenario. In this context, the main objective of this dissertation is to analyze the behavior of a generic distribution network with distributed generation penetration and to evaluate the voltage profile before different levels of insertion of this generation in the network. The solid state transformer has instantaneous voltage adjustment characteristics and interaction capacity with storage systems, which were used to aid in the regulation of voltage levels that were out of the standards determined by ANEEL resolution 794/2018, when a high level of distributed g... (Complete abstract click electronic access below)
Mestre
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Kendall, Haydn G. "Investigation of leakage flux in transformer tanks." Thesis, Cardiff University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329641.
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Wolf, Marko. "Design and implementation of a modular converter with application to a solid state transformer." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2773.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2009.ENGLISH ABSTRACT: The purpose of a solid state transformer (SST) is to use power electronic converters to mimic the operation of the conventional distribution transformer. These power electronic converters are proposed to overcome the disadvantages of the conventional distribution transformer. The advantages of a SST include near perfect voltage regulation and harmonic isolation between the primary and secondary windings of the transformer. This thesis discusses the design and development of the different converters in a solid state transformer (SST). A prototype modular back-to-back converter is developed for the input and isolation stage of the SST. The isolation stage consists of a high voltage DC-DC converter, which transfers power across the isolation barrier of the SST. This stage is evaluated in the laboratory with special attention being paid to the efficiency of the converter. The second aspect that this thesis addresses is the output stage of the SST, namely a three phase inverter. The discussion of the output stage focuses on the losses occurring in the inverter. The switching device losses are calculated by means of an adapted numerical method as opposed to using conventional analytical methods. The presented numerical method is compared to the existing analytical method and the findings are discussed. A double loop control strategy is implemented for the output stage inverter. The inner current loop utilizes a predictive control strategy. The control analysis of the double loop controller is discussed and evaluated in the laboratory. All the converters that are discussed in this thesis are evaluated in the laboratory and the relevant measurements are included.
AFRIKAANSE OPSOMMING: Die doel van ’n drywingselektroniese transformator (DET) is om drywingselektroniese omsetters te gebruik om die werking van die konvensionele distribusietransformator na te boots. Hierdie drywingselektroniese omsetters word voorgestel ten einde die nadele van die konvensionele distribusietransformator te bowe te kom. Die voordele van ’n DET sluit in: feitlik perfekte regulering van spanning en harmoniese isolasie tussen die primˆere en sekondˆere windings van die transformator. Hierdie tesis bespreek die ontwerp en ontwikkeling van die verskillende omsetters in ’n drywingselektroniese transformator (DET). ’n Prototipe modulˆere rug-aan-rug-omsetter word ontwikkel vir die intree- en isolasiefase van die DET. Die isolasiefase bestaan uit ’n hoogspanning- GS-GS omsetter, wat drywing oor die isolasiegrens van die DET heen oordra. Hierdie omsetter word in die laboratorium ge¨evalueer met besondere aandag aan die doeltreffendheid van die omsetter. Die tweede aspek waarna in hierdie tesis gekyk word, is die uittreefase van die DET, naamlik ’n driefaseomsetter. Die bespreking van die uittreefase fokus egter op die verliese wat in die omsetter voorkom. Die verliese van die skakelaars word bereken deur middel van ’n aangepaste numeriese metode teenoor die gebruik van konvensionele analitiese metodes. Die numeriese metode wat aangebied word, word vergelyk met die bestaande analitiese metode en die bevindings word bespreek. ’n Dubbellus-beheerstrategie word vir die uittreefase-omsetter ge¨ımplementeer. Die binneste stroomlus word ge¨ımplementeer deur van ’n voorspelbare beheerstrategie gebruik te maak. Die beheeranalise van die dubbellusbeheerder word bespreek en in die laboratorium ge¨evalueer. Al die omsetters wat in hierdie tesis bespreek word, word in die laboratorium ge¨evalueer en die relevante metings word ingesluit.
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Hills, M. "Solid state sensors for gas monitoring and control." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604069.
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A probe for the continuous on-line measurement of hydrogen dissolved in liquid aluminium has been developed using the perovskite proton conductor CaZrO3-In, in conjunction with a Zr,ZrH2 solid state reference. The probe has been designed to an industrial prototype standard, and measurements were in good agreement with established (but cumbersome) hydrogen measurement methods such as the AISCAN analyser, LECO analysis, and the Straube-Pfeiffer technique. The electrolytic domain of CaZrO3-In has been investigated using a novel double-cell arrangement to simultaneously fix the chemical potential of both hydrogen and oxygen at the electrodes of a pellet of the electrolyte. As predicted from the defect equilibria, the electrolyte makes the transition from the hydrogen ion conduction domain to the oxygen ion domain under conditions of low oxygen partial pressure and high hydrogen partial pressure. The pO2 corresponding to the Zr,ZrO2 equilibrium is low enough to locate CaZrO3-In in the oxygen ion conduction domain. Sodium b-alumina was employed to measure the pO2 developed under operating conditions at the sensor reference electrode by a sample zirconium containing dissolved oxygen. This was found to be many orders of magnitude higher than the pO2 corresponding to the Zr,ZrO2 equilibrium, and was five magnitude higher than the pO2 marking the H+/O2- conduction domain boundary for CaZrO3-In, suggesting that Zr, ZrH2 may be suitable as a reference material. Hydrogen sensors manufactured using CaZrO3-In as the solid electrolyte and a Zr,ZrH2 solid state reference were found to provide stable, reproducible emfs at constant temperature and pH2, and showed full Nernstian response following a change in pH2 at the measuring electrode. The recently developed Current Reversal Mode can accurately determine the emf of a solid electrolyte sensor, and also provides additional information in the form of the sensor resistance. A detailed study has identified how the CRM parameters should be selected in order to make accurate measurements. The sensor resistance measurement was used to improve measurement accuracy and stability of an internally heated yttria stabilised zirconia oxygen sensor. When applied to a commercially available probe for measuring hydrogen dissolved in liquid aluminium it was found that erroneous emf readings, measured after prolonged use in the melt, were accompanied by a corresponding increase in the sensor resistance, opening up the possibility of using CRM as an on-line diagnostic tool.
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Lubeigt, Walter. "Intra-cavity adaptive optics control of solid-state lasers." Thesis, University of Strathclyde, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431784.
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Storcz, Markus J. "Decoherence, control, and encoding of coupled solid-state quantum bits." Diss., lmu, 2005. http://nbn-resolving.de/urn:nbn:de:bvb:19-46047.
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Chesworth, Andrew Alexander. "Mode control in thin slab, diode pumped solid state lasers." Thesis, Heriot-Watt University, 1998. http://hdl.handle.net/10399/649.
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Vora, Kushan. "Modeling, analysis and control of flexible solid-state hysteretic actuators." Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1239895543/.
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Foy, Christopher Ph D. (Christopher C. )Massachusetts Institute of Technology. "Solid-state spin-integrated circuits for quantum sensing and control." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127017.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 131-138).
Spin systems are an increasingly important quantum-sensing platform. In particular, atomic defect centers in diamond called nitrogen-vacancy (NV) centers offer impressive room temperature imaging capabilities for both magnetic fields and temperature. NV-based sensing platforms have found utility in solid-state physics, biological systems, and vector magnetometry. These applications highlight the immense promise of NV quantum sensors. Despite this promise, the use of NV centers within commercial devices remains limited to date, with many impediments to transitioning this platform from the laboratory. This thesis describes the development of solid-state spin-integrated circuits (S3IC) for quantum sensing and control with the overarching goal of creating scalable NV platforms. We present two major experiments that develop S3IC. These expand the application space of NV centers and improve device functionality. The first application was to develop an NV spin microscope capable of wide-field temperature and magnetic field imaging to elucidate functional device behavior at the microscopic scale. The second experiment was integrating the essential components of an NV spin microscope, spin control and detection, with integrated electronics. In this manner, S3IC combines the exceptional sensitivity of NV centers with the robustness and scalability of modern electronic chip-scale platforms. This co-integration of spin systems into integrated electronics shows a potential path for migrating previous proof-of-principal sensing demonstrations into affordable packages that demonstrate both much greater system integration and custom electronic architectures. In short, this work demonstrates advances in NV-ensemble quantum sensing platforms and establishes a foundation for future integration efforts, perhaps inspiring innovations in both application space and the development of new quantum devices.
by Christopher C. Foy.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
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Topple, Jessica. "Molecular thin films:characterization, control, and collection of light." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=107776.
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Deposition of submonolayer coverages of 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) onto NaCl(001) results in the bimodal growth of coexisting square and needle-shaped islands. The epitaxy of each island type was determined from molecular and atomic resolution non-contact atomic force microscopy (NC-AFM) images. Post-deposition, the needle islands grow while the square islands disappear completely within days. This is characterized as a dewetting transition, the dynamics of which has been described and empirically fit to the monomolecular growth model, a model typically applied to biological growth.Methods of tailoring molecular thin film morphology and maturation rate were investigated. The island surface distribution, size, shape, and rate of dewetting of submonolayer coverages of PTCDI on alkali halides may be varied by changing growth conditions such as temperature and by templating the substrate with single atomic layer deep pits or depositing gold nanoclusters to modify island nucleation. This characterization is an important step in controlling the structure of thin organic films for devices that are sensitive to nanoscale film structure.Film morphology of organic photovoltaic materials can have a dramatic influence on device performance. Building upon previous morphological studies of tailoring molecular island size and nucleation site distribution, thin films of PTDCI (an electron donor) and copper (II) phthalocyanine (an electron acceptor) molecular islands were grown under ultra high vacuum conditions. Topography and surface contact potential were simultaneously mapped in a preliminary NC-AFM and Kelvin probe force microscopy study investigating structure-function relationships in photovoltaic energy generation.Le dépôt de sous-couche simples de 3,4,9,10-pérylénetetracarboxylic diimide (PTCDI) sur du NaCl (001) résulte en une croissance bimodale d'îles en formes d'aiguille et de carré. L'épitaxie de chaque type d'île a été déterminé par imagerie microscopique à force atomique non-contact (NC-AFM) avec des résolutions atomiques et moléculaires. Aprés le dépôt, les îles en forme d'aiguille croissent tandis que les îles de forme de carrés disparaissent complètement en quelques jours. Ceci est caractérisé par une transition de démouillage, pour laquelle la dynamique a été décrite et empiriquement ajusté au modèle de croissance mono-moléculaire, un modèle généralement appliqué aux croissances biologiques. Les méthodes d'adaptation de la morphologie des couches moléculaires minces et le taux de maturation ont été étudiés. La distribution de surface, la taille et la forme des îles, ainsi que le taux de démouillage des sous-couche simples de PTCDI sur les alkali-halides peuvent être modifiés en changeant les conditions de croissance telles que la température, en remodelant le substrat avec des trous profonds d'épaisseur atomique ou en déposant des nano-amas d'or pour modifier la nucléation des îles. Cette caractérisation est une étape importante pour le contrôler la structure des films organiques fins pour des appareils qui sont sensibles à la structure des films aux échelles nanoscopiques. La morphologie des films de matériaux organiques photovoltaïques peut avoir une influence importante sur la performance de ces appareils. En s'appuyant sur des études antérieures portant sur l'adaptation de la taille des îles moléculaires et la répartition des sites de nucléation, des films minces d'îles de PTDCI (un donneur d'électrons) et de cuivre (II) phthalocyanine (un accepteur d'électrons) ont été cultivés sous ultra haut vide. La topographie et le potentiel de contact à la surface ont été cartographié simultanément dans une étude préliminaire de microscopies NC-AFM et sonde Kelvin pour caractériser les relations entre la structure et la fonction de la génération d'énergie photovoltaïque.
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Hodson, P. D. "Magnetic property control in ferromagnetic amorphous alloys." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373248.
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Liu, Ru-Shi. "The chemical control of high temperature superconductivity." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240144.
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Pennock, S. "Topics in the plasmatic control of dielectric waveguides." Thesis, University of Bath, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374839.
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Ford, John. "Structure and orientational control in main chain liquid crystal polymers." Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304678.
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Zheng, G. L. "Self-tuning control of a plasma position in a tokamak machine." Thesis, University of Manchester, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332780.
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Giles, Luis Felipe. "Characterization and control of crystallographic defects in thin film SIMOX materials." Thesis, University of Surrey, 1994. http://epubs.surrey.ac.uk/844322/.
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Crystallographic defects present in the silicon over layer of thin (< 1000 A) SIMOX material have been characterized using a newly developed etchant and by transmission electron microscopy. Rutherford backscattering spectroscopy has also been used to determine the chemical composition and thickness of the synthesised layers. The thin SIMOX layers were produced by two different methods, namely (i) sacrificial oxidation of the silicon over layer of thick (2000 A) SIMOX films and (ii) low energy O+ implantation. The main crystallographic defects present in materials prepared by sacrificial oxidation are threading dislocations and oxidation induced stacking faults (OISF) whose density and size depends mainly upon the oxidation conditions (temperature, time) and also on the number of nucleation sites present before oxidation. The nucleation of these OISF has been investigated and it has been observed that stacking fault (SF) complexes are the main nucleation sites. The density of threading dislocations within the Si over layer does not increase during oxidation. The lowest density of OISF (5.0x102 cm-2) was observed in layers thinned by dry oxidation although some layers contained up to 5.0x105 cm-2. This difference in OISF densities was attributed to differences in the densities of the SF complexes before oxidation. Thin film SIMOX structures formed by low energy implantations also contain two principal defect types namely, threading dislocations and stacking fault complexes, where the densities depend upon the implantation and annealing conditions, A low density of threading dislocations is only obtained when parameters, such as dose and implantation temperature are optimised. Furthermore, it is also observed that thermal and mechanical stresses produced in the silicon over layer during implantation or annealing, need to be minimised in order to obtain low defect density material. It has been shown by whole wafer defect mapping of six inch SIMOX wafers implanted under optimised conditions, that a uniform distribution of defects can be achieved, having an average defect density as low as 1.0x104 cm-2. Additionally, the effects of implantation damage on the formation of secondary defects have also been investigated. The results have shown that the coalescence of point defects generated during implantation produce a high density of dislocation loops that, depending upon the annealing treatment, develop into threading dislocations or OISF. These experiments confirm that careful optimisation of the processing conditions, such as implantation temperature and dose uniformity, can significantly reduce defect densities thus enhancing the prospect of thin film SIMOX as a suitable substrate for fully depleted MOS devices.
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Hall, Gareth W. "Control of the properties of semiconducting thin films deposited using magnetron sputtering." Thesis, Loughborough University, 1993. https://dspace.lboro.ac.uk/2134/12927.
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The objective of the work was to deposit semiconducting thin films with controlled properties using unbalanced reactive magnetron sputtering. It was decided to utilise this technique because it offers high deposition rate and controllable in-situ ion bombardment of the growing film, desirable attributes from both research and production perspectives. Sputtering from a metal cathode in a reactive gas atmosphere introduces process instabilities which can result in a low degree of control over the stoichiometry, optical, electrical and structural properties of the films. Whilst the focus of the study was to achieve repeatable control over semiconducting film properties, additional areas of interest associated with the reactive sputtering process were investigated as the project developed. Improvements in magnetron design have been made to remove iron contamination from the extended poles, at the same time improving cathode utilisation. A new technique of bonding polycrystalline silicon cathodes to cooling shims has been developed using a sputtered threemetal multilayer process. DC sputtering of silicon in the presence of oxygen, nitrogen, nitrogen and oxygen, and nitrogen and air has been used to produce films of refractive index between 2.27 and 1.45 at rates between 0.5 and 2 nms-1 depending on composition. Refractive index and optical transmittance of the films have been closely controlled by varying gas flow and composition, and substitution of air for oxygen increased the sensitivity so that indices of oxy-nitride films could be tailored to one decimal place. The deposition of Indium-tin-oxide (ITO) onto glass substrates has been investigated, using a feedback control loop to control the otherwise unstable process.
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Findlay, Robert Buchanan. "Control of the orientation and microstructure of some side chain liquid crystalline polymers." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386701.
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Bhardwaj, Rajni Miglani. "Experimental and computational approaches for control and prediction of solid-state of pharmaceuticals." Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=22739.
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This thesis illustrates techniques for discovery of solid-state forms and probing the relationship between molecular structure and crystallisability. Also, the value of combined experimental and computational approaches to provide better understanding of the key factors underpinning the structural diversity in two groups each comprising of two structurally related pharmaceutical compounds is demonstrated. An effective methodology of high throughput crystallisation and analysis for polymorph, solvate and salt screening using quartz 96/48 multi well plate with an automated system for collecting high quality Raman spectra was developed and validated. Using this efficient technique, 10 novel salts of amoxapine, 3 novel physical forms of clozapine and 16 novel solid forms of olanzapine were obtained by utilising a total of only ~640 mgs of API and ~65 ml of solvents. A statistical model with ~70% prediction accuracy has been built for predicting the crystallisability of small organic m olecules. This model is first of its type and provides an opportunity to identify problematic systems at early stages and would allow early targeting for improvements. Structurally related molecules within each group were found to have markedly different experimental solid-state diversity after comprehensive physical form screening using multiple crystallisation techniques selected to maximise the crystallisation search space. Crystal structure prediction studies have been proved to be an important tool in rationalisation of the observed solid-state diversity. PIXEL calculations revealed that the largest contribution to crystal stabilisation comes from dispersion energy and enabled the identification of dominant intermolecular interactions in the crystal structures. Structural packing analysis using XPac and Mercury has enabled the structural relationship amongst all the crystal structures to be investigated. In case of olanzapine solvates XPac analysis provides a rationale of desolvation products by highlighting the close relationships between the forms and desolvated 'end product'. Statistical modelling analysis revealed that the physicochemical properties of the solvents were directing the crystal packing in olanzapine solvates.
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Holl, Mark Roland. "Dynamic analysis, measurement, and control of cell growth in solid state polymeric foams /." Thesis, Connect to this title online; UW restricted, 1995. http://hdl.handle.net/1773/7120.
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Fei, Chao. "Optimization of LLC Resonant Converters: State-trajectory Control and PCB based Magnetics." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/83206.
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With the fast development of information technology (IT) industry, the demand and market volume for off-line power supplies keeps increasing, especially those for desktop, flat-panel TV, telecommunication, computer server and datacenter. An off-line power supply normally consists of electromagnetic interference (EMI) filter, power factor correction (PFC) circuit and isolated DC/DC converter. Isolated DC/DC converter occupies more than half of the volume in an off-line power supply and takes the most control responsibilities, so isolated DC/DC converter is the key aspect to improve the overall performance and reduce the total cost for off-line power supply.
On the other hand, of all the power supplies for industrial applications, those for the data center servers are the most performance driven, energy and cost conscious due to the large electricity consumption. The total power consumption of today's data centers is becoming noticeable. Moreover, with the increase in cloud computing and big data, energy use of data centers is expected to continue rapidly increasing in the near future. It is very challenging to design isolated DC/DC converters for datacenters since they are required to provide low-voltage high-current output and fast transient response.
The LLC resonant converters have been widely used as the DC-DC converter in off-line power supplies and datacenters due to its high efficiency and hold-up capability. Using LLC converters can minimize switching losses and reduce electromagnetic interference. Almost all the high-end offline power supplies employs LLC converters as the DC/DC converter.
But there are three major challenges in LLC converters. Firstly, the control characteristics of the LLC resonant converters are very complex due to the dynamics of the resonant tank. This dissertation proposes to implement a special LLC control method, state-trajectory control, with a low-cost microcontroller (MCU). And further efforts have been made to integrate all the state-trajectory control function into one MCU for high-frequency LLC converters, including start-up and short-circuit protection, fast transient response, light load efficiency improvement and SR driving.
Secondly, the transformer in power supplies for IT industry is very bulky and it is very challenging to design. By pushing switching frequency up to MHz with gallium nitride (GaN) devices, the magnetics can be integrated into printed circuit board (PCB) windings. This dissertation proposes a novel matrix transformer structure and its design methodology. On the other hand, shielding technique can be employed to suppress the CM noise for PCB winding transformer. This dissertation proposes a novel shielding technique, which not only suppresses CM noise, but also improves the efficiency. The proposed transformer design and shielding technique is applied to an 800W 400V/12V LLC converter design.
Thirdly, the LLC converters have sinusoidal current shape due to the nature of resonance, which has larger root mean square (RMS) of current, as well as larger conduction loss, compared to pulse width modulation (PWM) converter. This dissertation employs three-phase interleaved LLC converters to reduce the circulating energy by inter-connecting the three phases in certain way, and proposed a novel magnetic structure to integrated three inductors and three transformers into one magnetic core. By pushing switching frequency up to 1MHz, all the magnetics can be implemented with 4-layer PCB winding. Additional 2-layer shielding can be integrated to reduce CM noise. The proposed magnetic structure is applied to a 3kW 400V/12V LLC converter.
This dissertation solves the challenges in analysis, digital control, magnetic design and EMI in high-frequency DC/DC converters in off-line power supplies. With the academic contribution in this dissertation, GaN devices can be successfully applied to high-frequency DC/DC converters with MHz switching frequency to achieve high efficiency, high power density, simplified but high-performance digital control and automatic manufacturing. The cost will be reduced and the performance will be improved significantly.Ph. D.
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Gills, Zelda Y. "Dynamical control of irregular intensity fluctuations in a chaotic multimode solid state laser system." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/29859.
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Wolm, Patrick. "Dynamic Stability Control of Front Wheel Drive Wheelchairs Using Solid State Accelerometers and Gyroscopes." Thesis, University of Canterbury. Mechanical Engineering, 2009. http://hdl.handle.net/10092/4451.
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While the active dynamic stability of automobiles has increased over the past 17 years there have been very few similar advances made with electrically powered wheelchairs. This lack of improvement has led to a long standing acceptance of less-than-optimal stability and control of these wheelchairs. Accidents due to loss of stability are well documented. Hence, the healthcare industry has made several efforts for improved control of electric powered wheelchairs (EPWs) to provide enhanced comfort, safety and manoeuvrability at a lower cost. In response, an area of stability control was identified that could benefit from a feedback control system using solid state sensors.
To design an effective closed–loop feedback controller with optimal performance to overcome instabilities, an accurate model of wheelchair dynamics needed to be created. Such a model can be employed to test various controllers quickly and repeatedly, without the difficulties of physically setting a wheelchair up for each test. This task was one central goal of this research.
A wireless test-bed of a front wheel drive (FWD) wheelchair was also developed to validate a dynamic wheelchair model. It integrates sensors, a data control system, an embedded controller, and the motorised mechanical system. The wireless communication ensures the integrity of sensor data collected and control signals sent. The test-bed developed not only facilitates the development of feedback controllers of motorised wheelchairs, but the collected data can also be used to confirm theories of causes of dynamic instabilities. The prototype test-bed performed the required tasks to satisfaction as defined by the sponsor.
Data collected from live tests in which the test-bed followed set patterns, was processed and analysed. The patterns were designed to induce instability. The analysis revealed that an occupied wheelchair is more stable than an unoccupied wheelchair, disproving an initial instability theory proposed in this research. However, a proximal theory explaining over-steer is confirmed.
Two models of the FWD test-bed were created. First, a dynamic model inherited from prior research, based on equations of motion was tested and enhanced based on measured data. However, even with alterations to correct parameter values and variables in the equations, a complete model validation was not possible. Second, a kinematic model was created with a factor to compensate for dynamics not normally accounted in kinematic models. The kinematic model was partially validated versus the measured data. Although, still highly accurate, there is room for improvement in this model. Both models contained a sub-system drive motor model, to account for input forces to the FWD wheelchair system model, which is fully validated.
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Tarasov, Vladimir (Vladimir S. ). "Control of the self-assembly of alkanethiol-coated gold nanoparticles in the solid state." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43214.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.Includes bibliographical references (leaf 24).
A study of the behavior of nanoparticles in the presence of solvent vapors is presented. Millimeter-scale films of gold nanoparticles, one nanometer thick, are treated with solvent vapors at various temperatures and the behavior of the nanoparticles is tracked over time using transmission electron microscopy. The ultimate goal of this processing is to repair defects such as grains, dislocations, and vacancies in the original superlattice. Additionally, Langmuir-Schaeffer films of gold nanoparticles on water surfaces are subjected to thermal and ultrasonic treatment in an attempt to correct defects in the films, which are then transferred to solid substrates for observation. Unfortunately, none of these approaches is able to reduce the defect concentration in a lattice, although thermal treatment and sonication of Langmuir-Schaeffer nanoparticle films are found to provide a controllable approach to depositing exact double layers of nanoparticles.
by Vladimir Tarasov.
S.B.
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Alabert, Josep Carles. "Optical vapour pressure monitoring and mass transport control during bulk CdTe crystal growth in a novel multi-tube PVT system." Thesis, Durham University, 1998. http://etheses.dur.ac.uk/5020/.
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This work is concerned with the development of a new vapour growth system for the growth of high quality bulk CdTe crystals, and, in particular, the study of mass transport control and in situ vapour pressure monitoring during growth in this system. The Multi-tube Physical Vapour Transport (MPVT) apparatus designed in Durham incorporates several modifications and improvements from past PVT methods. The U-shaped system, which is based on the Markov design, consists of three main parts, namely the source, crossmember and growth tubes, and allows to some extent decoupling of the temperature fields between source and growth regions. The introduction of the crossmember is effectively the technological key that enables the use of a flow restrictor to control mass transport and the introduction of a non-intrusive optical absorption technique capable of monitoring the partial vapour pressures of the vapour elemental constituents, i.e. Cd atoms and Te(_2) molecules, as growth proceeds. The optical absorption in the near UV and Visible spectrum of Cd and Te(_2) vapours has been quantitatively studied. The non-overlapping of the tellurium and the cadmium absorption bands allowed the use of a simple and compact light and detection system for in situ monitoring of vapour partial Cd and Te(_2) pressures independently during growth in the MPVT apparatus. In particular, the optical absorption system is capable of monitoring, after suitable calibration, cadmium vapour pressures in the range 0.01 -20 mbar and tellurium vapour pressures in the range 0.1-18 mbar The use of porous silica discs for use as flow restrictors is quantitatively studied both using theory and experiment. The transport properties of these discs as a function of intrinsic parameters (porosity, dimensions and specific surface area) and extrinsic parameters (temperature, pressure and molecular weight of the gas) are evaluated experimentally in detail. The experimental results are found to agree with the predictions of standard theoretical expressions. In particular, for the case of a multicomponent vapour, i.e. Cd and Te(_2) vapour mixture, it is experimentally found that the porous silica flow restrictor can also set the stoichiometry of the vapour to a smaller value than that expected under congruent CdTe sublimation. It is shown that use of a porous silica disc in conjunction with dynamic pumping during growth allows the mass transport rate to be set to the desired value, and permits diffusionless transport. Modelling of the transport process under several possible flow regimes encountered during normal growth conditions is also presented. The model, which assumes that diffusion mechanisms are unimportant, allows expressions to be obtained for the mass transport rate through the flow restrictor (porous disc or capillary) in the crossmember, the growth rate and the stoichiometry of the vapour above the source and crystal. Optical monitoring during CdTe growth carried out in several growth runs confirms both the predictions of the model concerning the stoichiometry of the vapour and its usefulness as a possible tool to monitor the growth process and growth rate.
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Carline, Roger Timothy. "One dimensional modelling of the charge control in square quantum well pseudomorphic AlGaAs/InGaAs field effect transistors for use in device design." Thesis, University of York, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304163.
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Fraval, Elliot, and elliot fraval@gmail com. "Minimising the Decoherence of Rare Earth Ion Solid State Spin Qubits." The Australian National University. Research School of Physical Sciences and Engineering, 2006. http://thesis.anu.edu.au./public/adt-ANU20061010.124211.
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[Mathematical symbols can be only approximated here. For the correct
display see the Abstract in the PDF files linked below] This work has
demonstrated that hyperfine decoherence times sufficiently long for
QIP and quantum optics applications are achievable in rare earth ion
centres. Prior to this work there were several QIP proposals using
rare earth hyperfine states for long term coherent storage of optical
interactions [1, 2, 3]. The very long T_1 (~weeks [4]) observed for
rare-earth hyperfine transitions appears promising but hyperfine T_2s
were only a few ms, comparable to rare earth optical transitions and
therefore the usefulness of such proposals was doubtful.
¶
This work demonstrated an increase in hyperfine T_2 by a factor of 7 ×
10^4 compared to the previously reported hyperfine T_2 for
Pr^[3+]:Y_2SiO_5 through the application of static and dynamic
magnetic field techniques. This increase in T_2 makes previous QIP
proposals useful and provides the first solid state optically active
Lamda system with very long hyperfine T_2 for quantum optics
applications.
¶
The first technique employed the conventional wisdom of applying a
small static magnetic field to minimise the superhyperfine interaction
[5, 6, 7], as studied in chapter 4. This resulted in hyperfine
transition T_2 an order of magnitude larger than the T_2 of optical
transitions, ranging fro 5 to 10 ms. The increase in T_2 was not
sufficient and consequently other approaches were required.
¶
Development of the critical point technique during this work was
crucial to achieving further gains in T_2. The critical point
technique is the application of a static magnetic field such that the
Zeeman shift of the hyperfine transition of interest has no first
order component, thereby nulling decohering magnetic interactions to
first order. This technique also represents a global minimum for back
action of the Y spin bath due to a change in the Pr spin state,
allowing the assumption that the Pr ion is surrounded by a thermal
bath. The critical point technique resulted in a dramatic increase of
the hyperfine transition T_2 from ~10 ms to 860 ms.
¶
Satisfied that the optimal static magnetic field configuration for
increasing T_2 had been achieved, dynamic magnetic field techniques,
driving either the system of interest or spin bath were investigated.
These techniques are broadly classed as Dynamic Decoherence Control
(DDC) in the QIP community. The first DDC technique investigated was
driving the Pr ion using a CPMG or Bang Bang decoupling pulse
sequence. This significantly extended T_2 from 0.86 s to 70 s. This
decoupling strategy has been extensively discussed for correcting
phase errors in quantum computers [8, 9, 10, 11, 12, 13, 14, 15], with
this work being the first application to solid state systems.
¶
Magic Angle Line Narrowing was used to investigate driving the spin
bath to increase T_2. This experiment resulted in T_2 increasing from
0.84 s to 1.12 s. Both dynamic techniques introduce a periodic
condition on when QIP operation can be performed without the qubits
participating in the operation accumulating phase errors relative to
the qubits not involved in the operation.
¶
Without using the critical point technique Dynamic Decoherence Control
techniques such as the Bang Bang decoupling sequence and MALN are not
useful due to the sensitivity of the Pr ion to magnetic field
fluctuations. Critical point and DDC techniques are mutually
beneficial since the critical point is most effective at removing high
frequency perturbations while DDC techniques remove the low frequency
perturbations. A further benefit of using the critical point technique
is it allows changing the coupling to the spin bath without changing
the spin bath dynamics. This was useful for discerning whether the
limits are inherent to the DDC technique or are due to experimental
limitations.
¶
Solid state systems exhibiting long T_2 are typically very specialised
systems, such as 29Si dopants in an isotopically pure 28Si and
therefore spin free host lattice [16]. These systems rely on on the
purity of their environment to achieve long T_2. Despite possessing a
long T_2, the spin system remain inherently sensitive to magnetic
field fluctuations. In contrast, this work has demonstrated that
decoherence times, sufficiently long to rival any solid state system
[16], are achievable when the spin of interest is surrounded by a
concentrated spin bath. Using the critical point technique results in
a hyperfine state that is inherently insensitive to small magnetic
field perturbations and therefore more robust for QIP applications.
32
Blandy, Jack. "Soft chemical control of layered oxychalcogenides." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:0fcc2604-0e0d-4206-a0aa-3fdcc611e357.
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The structure, magnetic behaviour and chemistry of layered oxychalcogenides of composition A2MO2X2Ch2 (where A = Sr, Ba; M = Mn, Co, Ni, Cu, Zn; X = Cu, Ag and Ch = S, Se, Te) has been investigated by the synthesis of new compounds of this type and control of the properties of these compounds by oxidative deintercalation of Cu/Ag. I2 can be used to oxidatively deintercalate Cu from Sr2MnO2Cu1.5S2, forming Sr2MnO2Cu1.33S2, an incommensurately modulated compound, with a completely different Cu/vacancy ordering and antiferromagnetic ordering structure to the parent. This reaction is also probed in real-time, using in situ powder X-ray diffraction. Sr2MnO2Ag1.5Se2 was found to have an A-type magnetic ordering structure, similar to Sr2MnO2Cu1.5Se2. Sr2MnO2Cu1.8Te2 on the other hand with a lower Mn oxidation state shows only two-dimensional magnetic correlations, rather than long-range order. Extending the reaction with I2 to several Co-containing analogues revealed that ~ 25% Ag could be removed from Sr2CoO2Ag2Se2, sufficient to observe a change in magnetic behaviour, from antiferromagnetic to ferromagnetic. By contrast only ~11% Cu can be deintercalated from Sr2CoO2Cu2S2 and even less (~5%) from Sr2CoO2Cu2Se2. Neutron diffraction was used to examine the resultant changes in magnetic ordering. The novel compounds Sr2CuO2Cu2Se2 and Ba2CuO2-xCu2Se2 are related by substitution of the alkali-earth metal, but while Sr2CuO2Cu2Se2 is a stoichiometric compound with metal-like character, Ba2CuO2-xCu2Se2 is an oxygen-deficient semiconductor, with tuneable oxygen content. Unusual features are observed in the magnetic susceptibility measurements of Sr2NiO2Cu2Se2 that appear unrelated to this compound's long-range magnetic ordering, as probed by neutron diffraction. Furthermore, unusual peak splitting is observed in low-temperature powder X-ray diffraction patterns of this compound; this may plausibly be due to a photon-induced effect arising from the use of a high-energy beamline; although further measurements are required to examine this. Overall the work shows the flexibility and range of behaviour exhibited by a series of the transition metal oxide chalcogenides.
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Kabuß, Julia Verfasser], Andreas [Akademischer Betreuer] Knorr, and Oliver [Akademischer Betreuer] [Benson. "Solid state quantum optics : control of electrons, photons and phonons / Julia Kabuß. Gutachter: Andreas Knorr ; Oliver Benson." Berlin : Technische Universität Berlin, 2014. http://d-nb.info/106654655X/34.
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Beamish, Eric. "Precise Size Control and Noise Reduction of Solid-state Nanopores for the Detection of DNA-protein Complexes." Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23569.
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Over the past decade, solid-state nanopores have emerged as a versatile tool for the detection and characterization of single molecules, showing great promise in the field of personalized medicine as diagnostic and genotyping platforms. While solid-state nanopores offer increased durability and functionality over a wider range of experimental conditions compared to their biological counterparts, reliable fabrication of low-noise solid-state nanopores remains a challenge. In this thesis, a methodology for treating nanopores using high electric fields in an automated fashion by applying short (0.1-2 s) pulses of 6-10 V is presented which drastically improves the yield of nanopores that can be used for molecular recognition studies. In particular, this technique allows for sub-nanometer control over nanopore size under experimental conditions, facilitates complete wetting of nanopores, reduces noise by up to three orders of magnitude and rejuvenates used pores for further experimentation. This improvement in fabrication yield (over 90%) ultimately makes nanopore-based sensing more efficient, cost-effective and accessible.
Tuning size using high electric fields facilitates nanopore fabrication and improves functionality for single-molecule experiments. Here, the use of nanopores for the detection of DNA-protein complexes is examined. As proof-of-concept, neutravidin bound to double-stranded DNA is used as a model complex. The creation of the DNA-neutravidin complex using polymerase chain reaction with biotinylated primers and subsequent purification and multiplex creation is discussed. Finally, an outlook for extending this scheme for the identification of proteins in a sample based on translocation signatures is presented which could be implemented in a portable lab-on-a-chip device for the rapid detection of disease biomarkers.
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Kabuß, Julia [Verfasser], Andreas Akademischer Betreuer] Knorr, and Oliver [Akademischer Betreuer] [Benson. "Solid state quantum optics : control of electrons, photons and phonons / Julia Kabuß. Gutachter: Andreas Knorr ; Oliver Benson." Berlin : Technische Universität Berlin, 2014. http://d-nb.info/106654655X/34.
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Girbino, Michael James. "Detecting Distribution-Level Voltage Anomalies by Monitoring State Transitions in Voltage Regulation Control Systems." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1550483383962611.
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Hansom, Jack. "Environmental coupling in a quantum dot as a resource for quantum optics and spin control." Thesis, University of Cambridge, 2015. https://www.repository.cam.ac.uk/handle/1810/252641.
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A single spin confined to a semiconductor quantum dot is a system of significant interest for quantum information science, as a potential optically-addressable qubit. In many respects, a quantum dot behaves like a single atom with high quality single photon emission. By controlling the light-matter coupling in such a system, it is possible to generate highly non-classical states of light and coherently control a single spin confined to the quantum dot. A departure from the ideal atomic picture appears once we consider the mesoscopic environment with which the quantum dot interacts. Charge fluctuations in the surroundings of the quantum dot affect the photon emission frequency leading to inhomogeneous broadening. Further broadening of the emission is caused by coupling to phonon modes of the host semiconductor material. Finally, coupling between the spin of a confined electron and a large bath of nuclear spins residing in the quantum dot leads to fast dephasing of the electron spin. All of these effects are typically considered detrimental to the potential use of quantum dots for quantum technologies. In this thesis, we develop the environmental coupling of a negatively charged quantum dot as a resource for quantum optics and spin control. First, the phonon-assisted fluorescence is shown to be a useful independent channel for feedback stabilisation of the quantum dot emission frequency, without requiring a measurement of the indistinguishable zero-phonon line. With stabilisation, the corresponding frequency broadening is drastically improved, and the sub-Hz frequency fluctuations are no longer resolved. Next, we show low-power resonance fluorescence emission spectra of the negatively charged trion transition. In the low power regime of resonance fluorescence, the excited state is not populated and most of the emission is coherent. In addition to elastic Rayleigh scattering, we observe coherent Raman sidebands, linked to an effective magnetic field created by the hyperfine interaction, the Overhauser field. This fluctuating effective field lifts the electron spin degeneracy in the absence of a magnetic field, and dictates the optical selection rules of the trion system. These spectra therefore allow for a measurement of the time-averaged distributions of in-plane and out-of-plane Overhauser field components. In the final part of the thesis, we use this hyperfine-generated ? -scheme to optically create electron spin superpositions through two-colour excitation and coherent population trapping. We then show that rapid shifts in the relative phase of the lasers lead to initialisation of the electron spin into a rotated dark state.
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Huang, Mantao. "Voltage control of electrical, optical and magnetic properties of materials by solid state ionic transport and electrochemical reactions." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127898.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 139-153).
Reversible post-fabrication control of material properties enables devices that can adapt to different needs or environmental conditions, and brings additional levels of functionality, paving the way towards applications such as reconfigurable electronics, reconfigurable antennas, active optical devices and energy efficient data storage. One promising way of achieving the controllability is through solid-state ionic transport and electrochemical reactions in thin film structures, where the properties of materials can be electrically controlled by a gate voltage in an addressable way. Here we explore using such ionic gating method to control the electrical, optical and magnetic properties of solid-state thin film layers, and show that large modification can be achieved for a wide range of properties. We demonstrate a new type of three terminal resistive switching device where the resistivity of a thin film conductive channel can be controlled by a gate voltage. We demonstrate solid-state ionic gating of the optical properties of metals and oxides and show the versatility of the approach by implementing voltage-controlled transmission, thin film interference, and switchable plasmonic colors. We also show that the approach allows for voltage control of ferrimagnetic order, demonstrating voltage induced 180-degree switching of the Néel vector, as a new way of magnetic bit writing. These findings extend the scope of voltage programmable materials and provide insights into the mechanisms of voltage controlled material properties by solid-state ionic transport and electrochemical reactions.
by Mantao Huang.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Materials Science and Engineering
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韋盧溝 and Lo-kau Wai. "Microprocessor-based field-oriented control of a synchronous motor drive using a three-phase solid-state sinusoidal current source." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1988. http://hub.hku.hk/bib/B31208940.
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Wai, Lo-kau. "Microprocessor-based field-oriented control of a synchronous motor drive using a three-phase solid-state sinusoidal current source /." Hong Kong : University of Hong Kong, 1988. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12434425.
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Bensch, Hauke Magnus [Verfasser]. "Kontrolle der Pulsdynamik in modengekoppelten Hochenergie-Festkörperlasern : Control of the pulse-dynamics of a mode-locked high energy solid state laser / Hauke Magnus Bensch." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2018. http://d-nb.info/1172414513/34.
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Rust, Josefine. "Testsystem för processtyring." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-55171.
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Målet med det här arbetet var att implementera och bygga ett komplett testsystem för reglering som efterfrågades av företaget Prevas AB i Karlstad. De önskade ett testsystem som reglerar en vattentemperatur som de kan använda på kontoret för att genomföra egna tester, analyser samt lära nyanställda medarbetare mer om automation. Testsystemet har även ett tillhörande HMI (Machine Human Interface) som användaren styr regleringen ifrån. Regleringen i testsystemet använder PID(Proportional–integral–derivative)-reglering och är inställd med lambdametoden. PID-reglering är den vanligaste använda metoden inom tillverkningsindustrin för reglering, men trots det är det många av dagens PID-regleringar som underpresterar. En anledning är slitage i mekaniska ställdonen som finns i processerna. För att utvärdera att testsystemet fungerar samt för att visa vad det kan användas till, har en mindre analys av ett mekaniskt ställdon genomförts, där antalet tillslag för ett ställdon i det byggda systemet undersökts. Testsystemet som byggdes uppfyller de krav som ställts från Prevas och de är nöjda med resultatet. Analysen som genomfördes visade att testsystemet fungerade och kan användas till den typen av test. Analysen i sig visade att simulationen som implementerats i testsystemet inte fungerade som den skulle och därmed är några testresultat ogiltiga. Rapporten presenterar hur ett testsystem för reglering kan implementeras och sedan vad det kan användas till.
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Magalhães, de Oliveira Marcio. "Power Electronics for Mitigation of Voltage Sags and Improved Control of AC Power Systems." Doctoral thesis, KTH, Electric Power Systems, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3018.
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The thesis deals with the application of compensators andswitches based on power electronics in AC transmission anddistribution systems. The objective of the studieddevices/equipment is the power flow and voltage control intransmission systems and the mitigation of voltage sags andmomentary interruptions to critical loads in distributionsystems.
For validating the power electronics based devices/equipmentdescribed in the thesis, scaled models at a real-time simulatorhave been built. Simulation results of these models arepresented and discussed in the thesis.
The equipment studied in the thesis exploit the fast controlactions that can be taken by power electronics devices, whichare much faster than the speed of conventional equipment andprotection systems, based on electromechanical devices. In thisway, the power quality of distribution systems is improved,regarding duration and magnitude of voltage sags (dips) andmomentary interruptions, which are the most relevant types ofdisturbances in distribution systems.
The thesis presents some compensators based onforced-commutation voltage-source converters for correctingvoltage sags and swells to critical loads. The seriesconverter, usually denoted Dynamic Voltage Restorer (DVR), hasbeen proved suitable for the task of compensating voltage sagsin the supply network. The use of solid-state devices ascircuit breakers in distribution systems has also been studiedwith the objective of achieving fast interruption or limitationof fault currents. The location and practical aspects for theinstallation of these solid-state breakers are presented. Ithas beenshown that a configuration based on shunt and seriesconnected solid-state devices with controllable turn-offcapability can also provide voltage sag mitigation, without theneed of transformers and large energy storage elements.
The operation and control of two Flexible AC TransmissionSystem (FACTS) devices for voltage and power flow control intransmission systems, namely the Static Synchronous Compensator(STATCOM) and the Unified Power Flow Controller (UPFC),respectively, are also studied. A faster response compared totraditional equipment consisting of mechanically based/switchedelements is then achieved. This allows a more flexible controlof power flow and a secure loading of transmission lines tolevels nearer to their thermal limits. The behaviour of thesedevices during faults in the transmission system is alsopresented. Keywords: power electronics, power quality, voltagesags, voltage-source converters, Custom Power, FACTS, real-timesimulations, solid-state devices.
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Chung, Te-yuan. "THERMAL MANAGEMENT, BEAM CONTROL,AND PACKAGING DESIGNS FOR HIGH POWER." Doctoral diss., University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3879.
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Several novel techniques for controlling, managing and utilizing high power diode lasers are described. Low pressure water spray cooling for a high heat flux system is developed and proven to be an ideal cooling method for high power diode laser arrays. In order to enable better thermal and optical performance of diode laser arrays, a new and simple optical element, the beam control prism, is invented. It provides the ability to accomplish beam shaping and beam tilting at the same time. Several low thermal resistance diode packaging designs using beam control prisms are proposed, studied and produced. Two pump cavity designs using a diode laser array to uniformly pump rod shape gain media are also investigated.Ph.D.
Other
Optics and Photonics
Optics
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Rabelo, joca Davi. "Une Topologie CA-CC Baseé sur un Convertisseur Modulaire Multiniveau Entrelacé Faisible à Applications de Transformateur d’Électronique de Puissance." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC010/document.
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Ce travail concerne l'étude théorique,l’analyse numérique et la validationexpérimentale d'une topologie de convertisseurd’électronique de puissance basée sur unconvertisseur multiniveau modulaire entrelacéavec transformateur moyenne fréquence.L’architecture est adaptée pour l’étage deconversion AC-DC dans les applications detransformateur d'électronique de puissance pourla connexion entre un réseau alternatif moyennetension et un réseau continu basse tension.L’entrelacement réduit les pertes par conductiondans les interrupteurs. Le transformateurmoyenne fréquence 10 kHz assure une isolationgalvanique et connecte le convertisseurmultiniveau modulaire entrelacé à unconvertisseur pont complet. Avec comme pointde départ la structure, le principe defonctionnement, la modélisation, la technique demodulation et le schéma de commande sontdiscutés. Une caractéristique du convertisseur estla génération simultanée de la tension du réseaubasse fréquence et de la tension primaire dutransformateur moyenne fréquence.L'équilibrage de la tension des condensateurs etla minimisation du courant de circulation sontcombinés dans un seul algorithme. La commanderégule le courant alternatif et la tension du buscontinu, du côté haute tension, ainsi que latension continue et le flux de puissance, du côtébasse tension. La validation expérimentale duconvertisseur est réalisée avec un prototype de720 W monophasé à l’échelle réduite. Lesrésultats démontrent la stabilité du système decommande lors d'opérations en régimepermanent et dynamiques (pas de charge,inversion du flux de puissance)This work aims to present thetheoretical study, the numerical analysis and theexperimental validation of a power electronicsconverter topology based on an interleavedmodular multilevel converter with mediumfrequencytransformer. The architecture issuitable for the AC-DC stage in solid-statetransformer applications for the connectionbetween a medium-voltage AC grid and a lowvoltageDC grid. The interleaving reduces theswitch conduction losses. The 10 kHz mediumfrequencytransformer provides galvanicisolation and connects the interleaved modularmultilevel converter to a full-bridge converter.From the converter structure, the principle ofoperation, the modeling, the modulationtechnique, and the control scheme are discussed.One feature of the converter is the simultaneousgeneration of the low-frequency grid voltageand the medium-frequency transformer primaryvoltage. The capacitor voltage balancing and thecirculating currents minimization are combinedtogether in a single algorithm. The controlsystem regulates the AC current and the DC busvoltage, on the high-voltage side, and the DCvoltage and power flow, on the low voltage side.The experimental validation of the converter ismade with a scaled-down single-phase 720 Wprototype. The results demonstrate the controlsystem stability in steady-state and dynamic(load step, power flow inversion) operations
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Foster, Geoffrey M. "DEFECT AND METAL OXIDE CONTROL OF SCHOTTKY BARRIERS AND CHARGE TRANSPORT AT ZINC OXIDE INTERFACES." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524050368601169.
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Boberg, Björn, and David Holm. "FEM modeling of concrete gravity dams." Thesis, KTH, Vattendragsteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-99351.
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PAES, JOAO P. F. "Estudo de lasers Raman para dobramento de frequência no azul." reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/27975.
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Submitted by Marco Antonio Oliveira da Silva (maosilva@ipen.br) on 2017-11-09T11:26:50Z
No. of bitstreams: 0Made available in DSpace on 2017-11-09T11:26:50Z (GMT). No. of bitstreams: 0
Os lasers Raman permitem a exploração de novos comprimentos de onda, não comumente acessíveis, graças ao Espalhamento Raman Estimulado. Unidos a processos de conversão não linear, abrem-se campos para emissão de comprimentos de onda na região do visível no espectro eletromagnético. Com uma mesma configuração, diversas combinações de cristais possibilitam a geração de múltiplas frequências, transformando esse tipo de laser em um dispositivo compacto e barato quando comparado com outras tecnologias existentes. Este trabalho apresenta a busca da conversão intracavidade em frequências de lasers Raman, em uma configuração linear. Com dois comprimentos de onda de bombeamento de energia (797 nm e 872 nm), diodos semicondutores foram utilizados para acessar dois picos de absorção do cristal Nd:YLF. O bombeamento em 797 nm levou a emissão fundamental em 908 nm. E através do cristal KGW, com linhas de emissão Stokes, um novo comprimento de onda foi alcançado, em 990 nm. Com o cristal dobrador, BiBO, soma de frequência e segundo harmônico foram gerados, permitindo as emissões em uma região espectral azul bastante larga (450 500 nm). Com o bombeamento em 872 nm, uma emissão de três níveis no cristal Nd:YLF não foi possível, conseguindo apenas a emissão em 1064 nm, linha comum para cristais de neodímio. Uma outra cavidade foi estudada, porém com bombeamento em 880 nm e cristal de Nd:YVO4, conhecido por ser self-Raman. Com uma configuração linear semelhante à anteriormente citada, somente sua linha de emissão fundamental em 914 nm foi obtida, não sendo possível com as condições trabalhadas a emissão Stokes, que permitisse dar continuidade ao estudo.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Wijesundara, Kushal Chinthaka. "Ultrafast Exciton Dynamics and Optical Control in Semiconductor Quantum Dots." Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1336648375.
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Gao, Hantian. "Nanoscale Characterization and Control of Native Point Defects in Metal Oxide Semiconductors and Device Structures." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1618838504594148.
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