Segui questo link per vedere altri tipi di pubblicazioni sul tema: Capacitors.
Tesi sul tema "Capacitors"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Vedi i top-50 saggi (tesi di laurea o di dottorato) per l'attività di ricerca sul tema "Capacitors".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Vedi le tesi di molte aree scientifiche e compila una bibliografia corretta.
1
Wynne, Edward McFaddin. "Determination of the Shelf Life of Aluminum Electrolytic Capacitors". Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3104/.
Testo completoAbstract (sommario):
The aluminum electrolytic capacitor is used extensively in the electric utility industry. A factor limiting the storage of spare capacitors is the integrity of the aluminum oxide dielectric, which over time breaks down contributing to a shelf life currently estimated at one nuclear power electric generating station to be approximately five years. This project examined the electrical characteristics of naturally aged capacitors of several different styles to determine if design parameters were still within limits. Additionally, the effectiveness of a technique known as “Reforming” was examined to determine its impact on those characteristics.
2
Bereza, Bill Carleton University Dissertation Engineering Electrical. "A switched-capacitor circuit technique used to measure capacitor mismatch and explore capacitor and opamp nonlinearity". Ottawa, 1988.
Cerca il testo completo
3
Yang, Fan. "Characterization of HFO2 Capacitors". Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/YangF2003.pdf.
Testo completo
4
Cousins, Jesse. "Simulation of the Variability in Microelectronic Capacitors having Polycrystalline Dielectrics with Columnar Microstructure". Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/CousinsJL2003.pdf.
Testo completo
5
Donahoe, Daniel Noel. "Moisture in multilayer ceramic capacitors". College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2189.
Testo completoAbstract (sommario):
Thesis (Ph. D.) -- University of Maryland, College Park, 2005.Thesis research directed by: Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
6
Larsson, Oscar. "Polyelectrolyte-Based Capacitors and Transistors". Doctoral thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-67852.
Testo completoAbstract (sommario):
Polymers are very attractive materials that can be tailored for specific needs and functionalities. Based on their chemical structure, they can for instance be made electrically insulating or semiconducting with specific mechanical properties. Polymers are often processable from a solution, which enables the use of conventional low-cost and high-volume manufacturing techniques to print electronic devices onto flexible substrates. A multitude of polymer-based electronic and electrochemical devices and sensors have been developed, of which some already has reached the consumer market. This thesis focuses on polarization characteristics in polyelectrolyte-based capacitor structures and their role in sensors, transistors and supercapacitors. The fate of the ions in these capacitor structures, within the polyelectrolyte and at the interfaces between the polyelectrolyte and various electronic conductors (a metal, a semiconducting polymer or a network of carbon nanotubes), is of outermost importance for the device function. The humidity-dependent polarization characteristics in a polyelectrolyte capacitor are used as the sensing probe for wireless readout of a passively operated humidity sensor circuit. This sensor circuit can be integrated into a printable low-cost passive sensor label. By varying the humidity level, limitations and possibilities are identified for polyelectrolyte-gated organic field-effect transistors. Further, the effect of the ionic conductivity is investigated for polyelectrolyte-based supercapacitors. Finally, by using an ordinary electrolyte instead of a polyelectrolyte and a high-surface area (supercapacitor) gate electrode, the device mechanisms proposed for electrolyte-gated organic transistors are unified.
7
Wang, Tong. "Electrospun carbon nanofibers for electrochemical capacitor electrodes". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/22563.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Textile and Fiber Engineering, Georgia Institute of Technology, 2007.Committee Chair: Satish Kumar; Committee Member: Anselm Griffin; Committee Member: John D. Muzzy; Committee Member: Ravi Bellamkonda; Committee Member: Rina Tannenbaum.
8
Muthana, Prathap. "Design of high speed packages and boards using embedded decoupling capacitors". Diss., Available online, Georgia Institute of Technology, 2007, 2007. http://etd.gatech.edu/theses/available/etd-05102007-121240/.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008.Prof Madhavan Swaminathan, Committee Chair ; Prof Rao Tummala, Committee Co-Chair ; Prof David Keezer, Committee Member ; Dr. Mahadevan Iyer, Committee Member ; Prof Suresh Sitaraman, Committee Member ; Prof William A. Doolittle, Committee Member.
9
Száraz, Ildikó. "Chemical reactions in aluminium electrolytic capacitors /". Luleå, 2003. http://epubl.luth.se/1402-1544/2003/05.
Testo completo
10
Krause, Andreas. "Ultrathin CaTiO3 Capacitors: Physics and Application". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-144522.
Testo completoAbstract (sommario):
Scaling of electronic circuits from micro- to nanometer size determined the incredible development in computer technology in the last decades. In charge storage capacitors that are the largest components in dynamic random access memories (DRAM), dielectrics with higher permittivity (high-k) were needed to replace SiO2. Therefore ZrO2 has been introduced in the capacitor stack to allow sufficient capacitance in decreasing structure sizes. To improve the capacitance density per cell area, approaches with three dimensional structures were developed in device fabrication. To further enable scaling for future generations, significant efforts to replace ZrO2 as high-k dielectric have been undertaken since the 1990s. In calculations, CaTiO3 has been identified as a potential replacement to allow a significant capacitance improvement. This material exhibits a significantly higher permittivity and a sufficient band gap. The scope of this thesis is therefore the preparation and detailed physical and electrical characterization of ultrathin CaTiO3 layers. The complete capacitor stacks including CaTiO3 have been prepared under ultrahigh vacuum to minimize the influence of adsorbents or contaminants at the interfaces. Various electrodes are evaluated regarding temperature stability and chemical reactance to achieve crystalline CaTiO3. An optimal electrode was found to be a stack consisting of Pt on TiN. Physical experiments confirm the excellent band gap of 4.0-4.2 eV for ultrathin CaTiO3 layers. Growth studies to achieve crystalline CaTiO3 indicate a reduction of crystallization temperature from 640°C on SiO2 to 550°C on Pt. This reduction has been investigated in detail in transmission electron microscopy measurements, revealing a local and partial epitaxial growth of (111) CaTiO3 on top of (111) Pt surfaces. This preferential growth is beneficial to the electrical performance with an increased relative permittivity of 55 with the advantage of a low leakage current comparable to that in amorphous CaTiO3 layers. A detailed electrical analysis of capacitors with amorphous and crystalline CaTiO3 reveals a relative permittivity of 30 for amorphous and an excellent value of 105 for fully crystalline CaTiO3. The permittivity exhibits a quadratic dependence with applied electric field. Crystalline CaTiO3 shows a 1-3% drop in capacitance density and permittivity at a bias voltage of 1V, which is significantly lower compared to all results for SrTiO3 capacitors measured elsewhere. A capacitance equivalent thickness (CET) below 1.0 nm with current densities 1×10−8 A/cm2 have been achieved on carbon electrodes. Finally, CETs of about 0.5 nm with leakage currents of 1 × 10−7 A/cm2 on top of Pt/TiN fulfill the 2016 DRAM requirements following the ITRS road map of 2012Die Verkleinerung von elektronischen Bauelementen hin zu nanometerkleinen Strukturen beschreibt die unglaubliche Entwicklung der Computertechnologie in den letzten Jahrzehnten. In Ladungsspeicherkondensatoren, den größten Komponenten in Arbeitsspeichern, wurden dafür Dielektrika benötigt, die eine deutlich höhere Permittivität als SiO2 besitzen. ZrO2 wurde als geeignetes Dielektrikum eingeführt, um eine ausreichende Kapazität bei kleiner werdenen Strukturen sicherzustellen. Zur weiteren Verbesserung der Kapazitätsdichte pro Zellfläche konnten 3D Strukturen in die Chipherstellung integriert werden. Seit den 1990ern wurden parallel bedeutende Anstrengungen unternommen, um ZrO2 als Dielektrikum durch Materialien mit noch höherer Permittivität zu ersetzen. Nach Berechnungen stellt nun CaTiO3 eine mögliche Alternative dar, die eine weitere Verbesserung der Kapazität ermöglicht. Das Material besitzt eine deutlich höhere Permittivität und eine ausreichend große Bandlücke. Diese Arbeit beschäftigt sich deshalb mit Herstellung und detaillierter physikalischer und elektrischer Charakterisierung von extrem dünnen CaTiO3 Schichten. Zusätzlich wurden diverse Elektroden bezüglich ihrer Temperaturstabilität und der chemischen Stabilität untersucht, um kristallines CaTiO3 zu herhalten. Als eine optimale Elektrode stellte sich Pt auf TiN heraus. Physikalische Experimente an extrem dünnen CaTiO3 Schichten bestätigen die Bandlücke von 4,0-4,2 eV. Wachstumsuntersuchungen an kristallinem CaTiO3 zeigen eine Reduktion der Kristallisationstemperatur von 640°C auf SiO2 zu 550°C auf Pt. Diese Reduktion wurde detailliert mittels Transmissionselektronenmikroskopie untersucht. Es konnte für einige Schichten ein partielles lokales epitaktischesWachstum von (111) CaTiO3 auf (111) Pt gemessen werden. Dieses Vorzugswachstum ist vorteilhaft für die elektrischen Eigenschaften durch eine gesteigerte Permittivität von 55 bei gleichzeitig geringem Leckstrom vergleichbar zu amorphen Schichten. Eine genaue elektrische Analyse von Kondensatoren mit amorphen und kristallinem CaTiO3 ergibt eine Permittivität von 30 für amorphe und bis zu 105 für kristalline CaTiO3 Schichten. Die Permittivität zeigt eine quadratische Abhängigheit von der angelegten Spannung. Kristallines CaTiO3 zeigt einen 1-3% Abfall der Permittivität bei 1V, der wesentlich geringer ausfällt als vergleichbare Werte für SrTiO3. Eine zu SiO2 vergleichbare Schichtdicke (CET) von unter 1,0 nm mit Stromdichten von 1×10−8 A/cm2 wurde auf Kohlenstoffsubstraten erreicht. Mit Werten von 0,5 nm bei Leckstromdichten von 1×10−7 A/cm2 auf Pt/TiN Elektroden erfüllen die CaTiO3 Kondensatoren die Anforderungen der ITRS Strategiepläne für Arbeitsspeicher ab 2016
11
Sallaz, Valentin. "Si-integrated capacitors for energy storage". Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASF022.
Testo completoAbstract (sommario):
Avec la nécessité de toujours plus miniaturiser l’électronique, les composants doivent aujourd’hui être compatibles avec le processus d’empilement 3D. Murata Integrated Passive Solutions (MIS) propose alors la technologie « Passive Integrated Connecting Substrate » (PICS), consistant à intégrer sur silicium des composants passifs. L’objectif, dans notre cas, est la réalisation de micro-supercondensateurs (MSCs) à fortes densités d’énergie (~10 J.cm⁻³) pour répondre aux besoins de stockage d’énergie. Cette étude s’est articulée autour de quatre points clés : (1) l’implémentation d’un électrolyte solide inorganique en couches minces pour MSCs, le LiPON, (2) l’optimisation des interfaces et des modes de stockage (surfacique ou volumique), (3) le développement d’un LiPON ultra fin déposé par Atomic Layer Deposition (ALD), enfin (4) l’augmentation de la surface spécifique du MSC à partir de procédés de nano structuration. L’ensemble du travail repose sur une étude systématique, couplant résultats électriques et électrochimiques à des analyses physico-chimiques poussées. L’électrolyte LiPON, lorsqu’intégré en configuration Métal – Isolant - Métal (MIM), a démontré un mode de stockage de type double couche électroniques (conformément aux EDLCs), avec de bonnes performances en termes de cinétique et d’énergie stockée. Cette dernière a pu être améliorée en implémentant une couche d’oxyde, du TiO₂, impliquant de nouveaux modes de stockage. La relation matériau/performance ainsi déterminée a servi de base pour le développement de MSCs ultra minces. La faisabilité d’un dépôt de LiPON par ALD électriquement fonctionnel a pu être démontrée, et son intégration dans des structures 3D à fort ratio d’aspect a permis de donner de premiers résultats encourageants quant aux performances cibléesWith the ever-increasing need for miniaturized electronics, components must be compatible with the 3D integration. Murata Integrated Passive Solutions (MIS) offers the Passive Integrated Connecting Substrate (PICS) technology, which integrates passive components on silicon. The objective of the present work is to fabricate high energy density micro-supercapacitors (MSCs) (~ 10 J.cm⁻³) to meet the energy storage needs. This study focused on four key points: (1) implementation of a thin film inorganic solid-state electrolyte for MSCs, LiPON, (2) interfaces and storage modes (surface or bulk) optimization, (3) development of ultrathin LiPON layers deposited by Atomic Layer Deposition (ALD), and (4) MSC specific surface area enhancement via nano structuring processes. The whole work is based on a systematic study, combining electrical and electrochemical results with advanced physical and chemical analysis. When integrated in a Metal – Insulator - Metal (MIM) configuration, the LiPON electrolyte exhibited an electronic double layer storage mode (like EDLCs), with good performance in terms of kinetics and stored energy. The latter was further improved by implementing an oxide layer, TiO₂, implying new storage modes. This material/performance relationship served as a basis for the development of ultra-thin MSCs. The feasibility of an electrically functional ALD LiPON deposition was demonstrated, and its integration into high aspect ratio 3D structures gave first encouraging results regarding the targeted performance
12
SINGH, VINIT. "HIGH TEMPERATURE CAPACITORS FOR VOLTAGE MULTIPLIERS". University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1085685724.
Testo completo
13
Reece, Richard O. "An investigation into structural electrochemical capacitors". Thesis, University of Surrey, 2016. http://epubs.surrey.ac.uk/811563/.
Testo completoAbstract (sommario):
This project investigated methods for manufacture of electrochemical capacitor, or supercapacitor, -based structural energy storage devices. Investigations were made into introducing structural components to supercapacitor designs, attempting to produce a cell with inherent load-bearing capability and mechanical strength. Design- led developments were also conducted into the combination of supercapacitors with composite materials, in particular embedding energy storage within sandwich panel composites and fibre reinforced polymer composites. Electrochemical and mechanical testing and analysis were performed experimentally on all designs. Electrochemical impedance spectroscopy was carried out at the frequency range 10 mHz to 1 MHz for all manufactured cells. Cyclic voltammetry was undertaken using scan rates in the range 0.5 mV/s to 10 V/s depending on supercapacitor size. Galvanostatic charge-discharge was performed for current densities ranging from 0.5 mA/cm2 to 30 mA/cm2. Together these testing regimes allow for presentation of electrode specific gravimetric capacitance, energy and power, total device specific gravimetric energy and power, and total device volumetric energy and power density. Mechanical testing was undertaken to the three- point bend test standard ASTM.D790, providing results for flexural modulus and strength. Initial investigations were carried out to explore the viability of solid or part-solid electrolytes using epoxy-electrolyte mixes, and mechanically stable electrodes using sulfur-graphene structural coatings doped with carbon nanomaterials. Later developments in the project introduced the incorporation of existing supercapacitor technology with organic liquid electrolytes into composite material panels. Novel contributions were made in the successful design of composite sandwich panels with embedded supercapacitors as structural energy storage devices. These designs used supercapacitor current collectors as multifunctional materials that provide strength to the sandwich panel core. Low and high-density designs were investigated, with additional preliminary work on supercapacitor embedded composite flat panels presented with a view to further development within the subject.
14
Jan, Saeed Ullah. "Dielectrics for high temperature capacitors applications". Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/11528/.
Testo completoAbstract (sommario):
Most of the dielectric materials developed in this thesis were relaxor dielectrics with very broad, frequency dependent peaks in relative permittivity-temperature, εr – T, plots. In some cases, plateau-like permittivity plots with very wide temperature ranges of stable permittivity varying by no more than ±15 % were obtained through compositional engineering of the relaxor base material using high levels of lattice substitution of cations of different charge and size to the host lattice. The solid solution series (1–x)Na0.5Bi0.5TiO3 – xBa0.8Ca0.2TiO3 [(1–x)NBT–xBCT] was studied initially: it showed little evidence of temperature-stable relative permittivity. However, 0.85NBT – 0.15BCT ceramics modified by BiMg0.5Ti0.5O3, [BMT], were more promising. The series, (1–x)[0.85Na0.5Bi0.5TiO3 – 0.15Ba0.8Ca0.2TiO3] – xBiMg0.5Ti0.5O3, x = 0.3, gave εr ~ 1720 ± 15 %, in the temperature range 120 to 450 ºC, and low dielectric loss tangent, tanδ ≤ 0.02, over the slightly narrower temperature range, 150 to 360 ºC. Thus an upper operating temperature > 300°C was demonstrated but without also achieving sub-zero temperature capability. Similarly, the system (1–x)[0.85Na0.5Bi0.5TiO3 – 0.15Ba0.8Ca0.2TiO3] – xLiNbO3 abbreviated [(1–x)[NBT – BCT] – xLN] gave εr ~ 2630 ± 15 % from 50 ºC to 410 ºC, and tanδ ≤ 0.02 from 120 ºC to 400 ºC, at composition x = 0.06. The incorporation of NaNbO3 [NN] in place of LiNbO3 achieved the desired sub-zero temperature capability in relative permittivity, and with an upper temperature limit slightly above 200 ºC. Examples include (1–x)[NBT – BCT] – xNN composition x = 0.3 with εr = 1400 ± 15 % from -50 to 240 °C and tanδ ≤ 0.02 from 20 ºC to 240 v ºC; for x = 0.4, εr = 1300 ± 15 % from -70 to 210 °C and tanδ ≤ 0.02 from -10 ºC to 210 ºC. In terms of the project goal of achieving a temperature range of stable permittivity combined with a low loss extending from temperatures of -55 °C (to meet the Electronic Industry Alliance military specification) up to 300 °C, the binary solid solution system (1–x)Ba0.6Sr0.4Zr0.2Ti0.8O3 – xBiMg0.5Ti0.5O3 [(1–x)BSZT – xBMT] was most promising. However there was a trade-off in that permittivity values were lower than the foregoing systems. The (1–x)BSZT – xBMT sample composition x = 0.2 gave εr ~ 500 ± 15%, in the temperature range -70 to 300 ºC and tanδ ≤ 0.02, in the range -60 to 300 ºC. This system closely matches the target temperature-range of the project, but the volumetric efficiency of a capacitor made from this dielectric would be compromised due its moderate relative permittivity values. Slightly higher values of relative permittivity were obtained for x = 0.3 in the (1–x)BSZT – xBMT series, with εr ~ 590 ± 15%, across the temperature range -60 to 340 ºC, but in this case the temperature range of low dielectric losses tanδ ≤ 0.02 was restricted to -10 to 280 ºC. Piezoelectric properties of selected samples have also been investigated in the thesis.
15
Saborío, González Maricruz. "Developmet of flexible electrodes and lightweight capacitors". Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/471808.
Testo completoAbstract (sommario):
This work has focused on the study and development of hierarchically, flexible electrodes and lightweight capacitor using as a source of flexibility. the y-polyglutamic acid (y-PGA) and as an electroactive polymer the poly(3,4-ethylenedioxythiophene) (PEDOT) in composite with alumina (Al2O3),Initially, the PEDOT/Al2O3 composite electroactive film was studied under different monomers: clay proportion and considering the amphoteric behavior of the Al2O3, the analysis of the pH affectation was done. Further, the multi-step in situ polymerization was studied. The experiments demonstrated that the 4:1 monomer: Al2O3 proportion, the multi-step basic medium (pH 8.8) (due to the proximity to the isoelectric point of the filler) favors the electrochemical properties with respect to pure PEDOT. The aforementioned variables combination displays an increment of 55% in specific capacitance (SC) (141 F g-1) compared to the pristine PEDOT. The values obtained demonstrate the synergetic effect of all the variables mentioned and the participation of the filler as a secondary doping agent facilitating the ion mobility.Secondly, the assembly and development of lightweight electrodes was achieved based on the supramolecular incorporation of PEDOT particles into an aqueous biohydrogel (y-PGA). Subsequently, a 20% w/w PEDOT particles were dispersed to give the electroactive characteristic to the gel, following by an extra step of in situ electropolymerization of poly(hydroxymethyl-3,4- ethylenedioxythiophene) (PHMeDOT) to join and increase the conductive polymer connections. Results revealed that electrochemical performance depends of the polymerization time, in this case, the optimum results obtained was the 7h polimerization electrode with a SC 45.4 ±0.7 mF cm-2 from cyclic voltammetry (CV) and charge-discharge (GCD) long-term stability. Finally, the applicability in lightweight and flexible energy-harvesting systems was verified by the LED bulb test. As a third step, a new solid organic symmetric capacitor was constructed, mingling the best results obtained from the previous studies as discussed. Two self-supported p-doped electrodes of y-PGA, PEDOT microparticles, PHMeDOT (2h electropolymerization) with filler of Al2O3 were produced. The electrodes were joined to a supporting solid ¿-PGA electrolyte doped with NaHCO3 salt from the synthesis step and functioning later as the electrolyte The electrochemical performance suggested an excellent prototype stability after 2000 charge-discharge cycles evidencing through an only 8% SC loss, evidencing an excellent stability.This thesis also focused in the n-doped PEDOT-polycation ionene electrode development. As a first step, a synthetic electrochemical protocol was followed to produce an n-doped PEDOT using macromolecular dopant agent, specifically, 1,4- diazabicyclo[2.2.2]octane-based ionene bearing N,N’-(meta-phenylene)dibenzamide linkages (mPi) was established. The protocol consisted of a three-step process , individually optimized: (1) preparation of p-doped (oxidized) PEDOT at a constant potential of +1.40 V in acetonitrile with LiClO4 as electrolyte; (2) dedoping of oxidized PEDOT using a fixed potential of –1.30 V in water; and (3) redoping of dedoped PEDOT applying a reduction potential of –1.10 V in water with mPI. The results obtained displayed a comparable doping level with respect tothe doping level obtained in case of TMA. Nevertheless, the PEDOT doped with mPi revealed better thermal stability and hydrophilicity than the former pristine p-doped and dedoped PEDOT. The final work, considers the influence of the ionene topology on the properties of n-doped PEDOT by comparing three isomeric topomers. The highest doping level was obtained for the para-isomeric ionene-containing electrode, even though the content of ortho- and meta-topomers into the corresponding ndoped PEDOT:ionene electrodes is greater , the topomers interactions as well were related with the hydrogelation of the ionenes.Este trabajo se ha centrado en el estudio jerárquico y desarrollo de electrodos flexibles y condensadores livianos utilizando como fuente de flexibilidad. el ácido ¿-poliglutámico (¿-PGA) y como polímero electroactivo el poli (3,4-etilendioxitiofeno) (PEDOT) en compuesto con alúmina (Al2O3), Inicialmente, la película electroactiva compuesta PEDOT / Al2O3 se estudi ó bajo diferentes proporciones de monómeros:Al2O3 y considerando el comportamiento anfótero del Al2O3, se realizó el análisis de la afectación del pH. Los experimentos demostraron que la proporción 4: 1, multicapa en medio básico (pH 8,8) (debido a la proximidad al punto isoeléctrico de la carga) favorece las propiedades electroquímicas con respecto al PEDOT puro. La combinación de las variables antes mencionadas resultan en un incremento de 55% de la capacitancia espec ífica (SC) (141 F g-1) en comparación con el PEDOT, por sí mismo. Los valores obtenidos demuestran el efecto sinérgico de todas las variables mencionadas y la participación del filler como agente dopante secundario facilitando la movilidad i ónica. En segundo lugar, el ensamblaje y desarrollo de electrodos ligeros se logr ó en base a la incorporación supramolecular de partículas de PEDOT en un bio-hidrogel acuoso (¿-PGA). Posteriormente, se dispersaron partículas de PEDOT al 20% m / m confiriendo la característica electroactiva al gel, seguido de una etapa adicional de electropolimerizaci ón in situ de poli (hidroximetil-3,4-etilendioxitiofeno) (PHMeDOT) para establecer conexiones entre las partículas de PEDOT e incrementar la conductividad. Los resultados indicaron que el rendimiento electroquímico depende del tiempo de polimerizaci ón, en este caso, los resultados óptimos obtenidos fue para el electrodo polimerizado 7h con un SC 45.4 ± 0.7 mF cm-2 de voltametría cíclica (CV) y mostrando una alta electro estabilidad. Finalmente, la aplicabilidad en sistemas ligeros y flexibles de almacenamiento de energía fue verificada con la prueba de la bombilla LED. Como tercer paso, se construyó un nuevo condensador simétrico orgánico sólido, basados en el know-how desarrollado de los estudios previos. Se produjeron dos electrodos p-dopados auto-soportados de ¿-PGA, micropartículas PEDOT, PHMeDOT (electropolimerización 2h) con relleno de Al2O3. Los electrodos se unieron a un electrolito de ¿-PGA sólido dopado con sal de NaHCO3 desde la etapa de s íntesis. El rendimiento electroquímico sugirió una excelente estabilidad del prototipo después de 2000 ciclos de carga y descarga, con s ólo una pérdida de SC del 8%. Esta tesis también se centró en el desarrollo del electrodo de ioneno - polietileno PEDOT n-dopado. Como primer paso, se siguió un protocolo de síntesis electroquímica para producir un PEDOT n-dopado utilizando un agente dopante macromolecular, específicamente, ioneno basado en 1,4-diazabiciclo [2.2.2] octano con N, N '- (meta-fenileno) dibenzamida (mPi). El protocolo consistió en un proceso de tres pasos, optimizados individualmente: (1) preparaci ón de PEDOT pdopado (oxidado) a un potencial constante de +1.40 V en acetonitrilo con LiClO4 como electrolito;(2) desdopadp de PEDOT oxidado utilizando un potencial fijo de -1,30 V en agua; y (3) redopado del PEDOT desdopado aplicando un potencial de reducción de -1.10 V en agua con mPI. Los resultados obtenidos muestran un nivel de dopaje comparable con respecto al nivel de dopaje obtenido en el caso de TMA. Sin embargo, el PEDOT dopado con mPi revel ó una mejor estabilidad térmica e hidrofilicidad que el antiguo PEDOT p-dopado y el desdopado . El trabajo final, considera la influencia de la topolog ía ioneno en las propiedades de PEDOT n-dopado mediante la comparaci ón de tres topómeros isoméricos.El nivel más alto de dopaje se obtuvo para el electrodo que contiene ioneno para-isomérico, aunque el contenido de orto y meta en los correspondientes electrodos de PEDOT: ioneno es mayor, las interacciones topoméricas también se relacionaron con la formación de gel
16
Nilsson, Johan, e Christoffer Fredriksson. "Planeringsverktyg för ABB Capacitors : Planering av körsekvens". Thesis, Uppsala University, Industrial Technology, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-126762.
Testo completoAbstract (sommario):
ABB Capacitors is looking to introduce LEAN within their organization. The purpose of this research is to suggest ways to improve the production planning in order to facilitate the company’s production processes. This should be done in accordance with the LEAN concept.
Today, ABB will produce two of the customers’ orders at the same time. To avoid major disturbances it is important to work with production planning to create a balanced production mix. During the planning it is important to consider that each order may create different “bottlenecks” in production line. Therefore, the aim of this project is to help ABB find an appropriate production mix with the incoming orders. Furthermore, the researchers have developed a tool which can facilitate the planning and make it easier and more sustainable.
The production process has been carefully observed and the capacity has been calculated for each station. The production capacity included the capacity of each station within the production line but also information from previous time studies has been used during the research. The time studies have been performed by a consultant though because the production process has developed since these studies were performed, the information had to be updated.
The updated information together with the calculated capacity of each station, have been used to create a spread sheet which can be used as a planning tool.
Recommendations for future actions have been developed, with help from the analysis and conclusions. These recommendations will support ABB in their future work.
17
Arikan, Mustafa. "Electrical Transport In Metal-oxide-semiconductor Capacitors". Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605489/index.pdf.
Testo completoAbstract (sommario):
The current transport mechanisms in metal-oxide-semiconductor (MOS) capacitors have been studied. The devices used in this study have characterized by current-voltage analyses. Physical parameter extractions and computer generated fit methods have been applied to experimental data. Two devices have been investigated: A relatively thick oxide (125 nm) and an ultra-thin oxide (3 nm) MOS structures. The voltage and temperature dependence of these devices have been explained by using present current transport models.
18
Miao, Bing. "Hafnium based MIM capacitors for hostile environments". Thesis, University of Newcastle Upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506721.
Testo completo
19
New, David Allen 1976. "Double layer capacitors : automotive applications and modeling". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28337.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 223-227).
This thesis documents the work on the modeling of double layer capacitors (DLCs) and the validation of the modeling procedure. Several experiments were conducted to subject the device under test to a variety of charging/discharging profile and temperatures in an effort to simulate the various conditions such a device might encounter in an automotive type application. High and low current charging profiles were performed for both charge/discharge and charge/hold/discharge type experiments. Low temperature ([approx.] -25 ⁰C), room temperature ([approx.] 21 ⁰C), and high temperature experiments ([approx.] 50 ⁰C) were performed for the investigation of temperature effects on these devices. The derived DLC model was used in PSpice® and Matlab® simulations to determine how accurately the model could predict the performance of the device. The nonlinear characteristics of the device were also investigated and the nonlinear modeling information presented as an addition to the basic DLC model. Device variation was explored for a small sample of these devices in an effort to gain insight on the range of tolerances for modern devices. This work also presents an extensive look into the variety of electrochemical capacitor devices under investigation and in use today. An explanation of these devices and their distributed resistances and capacitance is included. This thesis gives a detailed look into the experimental setups and testing procedures used to test the devices, the simulations for the comparison, and presents the results of the comparison. Finally, this thesis documents the conclusion that this simple model procedure adequately predicts the performance of the device under these various performance profiles.
by David Allen New.
S.M.
20
Collins, John L. "Radiation effects in metal-oxide-semiconductor capacitors". Thesis, Aston University, 1987. http://publications.aston.ac.uk/8078/.
Testo completoAbstract (sommario):
An investigation has been undertaken into the effects of various radiations on commercially made Al-SiO2-Si Capacitors (MOSCs). Detailed studies of the electrical and physical nature of such devices have been used to characterise both virgin and irradiated devices. In particular, an investigation of the nature and causes of dielectric breakdown in MOSCs has revealed that intrinsic breakdown is a two-stage process dominated by charge injection in a pre-breakdown stage; this is associated with localised high-field injection of carriers from the semiconductor substrate to interfacial and bulk charge traps which, it is proposed, leads to the formation of conducting channels through the dielectric with breakdown occurring as a result of the dissipation of the conduction band energy. A study of radiation-induced dielectric breakdown has revealed the possibility of anomalous hot-electron injection to an excess of bulk oxide traps in the ionization channel produced by very heavily ionizing radiation, which leads to intrinsic breakdown in high-field stressed devices. These findings are interpreted in terms of a modification to the model for radiation-induced dielectric breakdown based upon the primary dependence of breakdown on charge injection rather than high-field mechanisms. The results of a detailed investigation of charge trapping and interface state generation in such MOSCs due to various radiations has revealed evidence of neutron induced interface states, and of the generation of positive oxide charge in devices due to all of the radiations tested. In particular, the greater the linear energy transfer of the radiation, the greater the magnitude of charge trapped in the oxide and the greater the number of interface states generated. These findings are interpreted in terms of Si-H and Si-OH bond-breaking at the Si-SiO2 interface which is enhanced by charge carrier transfer to the interface and by anomalous charge injection to compensate for the excess of charge carriers created by the radiation.
21
Cagle, Clint William. "Charging kinetics of electric double layer capacitors". Connect to this title online, 2009. http://etd.lib.clemson.edu/documents/1263402254/.
Testo completo
22
Langham, Jacob. "Spiral pinballs, cardiac tissue and deforming capacitors". Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/90330/.
Testo completoAbstract (sommario):
‘Spiral pinballs’ are resonantly drifting spiral waves in excitable media that reflect from boundaries. Instead of reflecting at an angle equal to the one at which they approach the boundary—like a ray of light reflecting from a mirror—they reflect in a preferred direction. This invites comparison with a number of other complex systems that behave as nonspecular billiards, including bouncing droplets on a vibrated bath, swimming microorganisms and segments of chemical waves. In the first part of this thesis, we study the trajectories of spiral pinball reflections. A catalogue of interesting behaviours is discovered in both the small- and large-core rotation regimes and the long-term billiard dynamics is briefly considered. By using an asymptotic theory, we examine the reflection process in detail and thereby explain many of the observed phenomena. The second part of this thesis concerns itself with modelling spiral wave activity in a deforming medium. Our motivation stems from cardiac tissue, in which spiral waves and mechanical deformation are reciprocally coupled. We describe a simple modelling approach for this system and discuss its implementation. Various different results are presented using this model. Finally we consider a problem from the engineering world. Dielectric elastomers are flexible capacitors that undergo nonlinear elastic deformations in response to forces arising from electric surface charges. We propose a novel modelling approach that decomposes these forces into a compressive stress and a tangential shear. The tangential component corresponds to a fringing effect that is usually considered to be negligible. Via numerical simulations and comparison with experimental data we show that it nonetheless has an important role to play in selecting the deformed shapes that these systems adopt. In some cases, we are able to compute multiple equilibrium configurations and it is shown that doing so is necessary to obtain the most physically relevant states.
23
Premathilake, Dilshan V. "Vertically Oriented Graphene Electric Double Layer Capacitors". W&M ScholarWorks, 2017. https://scholarworks.wm.edu/etd/1516639673.
Testo completoAbstract (sommario):
Vertically oriented graphene nanosheets (VOGN) synthesized by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) have been fabricated as electrical double layer capacitors (EDLCs). The relatively open morphology of the films provided good frequency response, but had limited capacitance compared to present day activated carbon EDLCs. The objective of this research was to improve the capacitance of these films to a commercially viable level while maintaining sufficient frequency response for AC filtering. The growth of VOGN on Ni and Al substrates has been studied in this work. The native oxide on Ni was thinned at temperatures above ~600ºC with the oxygen from the surface oxide dissolving into the bulk, thus creating a low resistance ohmic contact that reduced the overall equivalent series resistance (ESR). Aluminum was studied because it is the primary substrate material used in electrolytic capacitors. However, it was much more difficult to work with because of its tenacious surface oxide. The maximum capacitance for a 10-minute VOGN/Ni growth observed was ~260µF/cm2, at temperature 850ºC, at 120 Hz, but the morphology was not very ordered. The best combination of capacitance (~160 µF/cm2) and frequency response (phase angle near -85º up to ~3000 Hz) was grown at 750ºC. The capacitance of VOGN/NI was further improved by using coatings of carbon black by an aerosol spray method. A capacitance of 2.3 mF/cm2 and frequency response phase angle near -90º at 120 Hz was achieved. It is the highest specific capacitance for an EDLC, reported in the literature, to date, suitable for AC filtering. Employing Al as a substrate required a novel method of plasma sputter cleaning of the oxide near the Al melting point (660ºC) and superimposing VOGN growth to prevent further oxidation. Initial results were ~80 µF/cm2 at a temperature of 620ºC with frequency response phase angle near -90º. Modeling of a uniform coating of carbon black (100 nm thick) on this underlying VOGN/Al architecture suggests that a capacitance of near 50 mF/cm2 can be achieved thus making this a potentially viable replacement for electrolytic capacitors. Another approach to commercialization of VOGN/Ni EDLCs has been studied by using a single substrate sheet interdigitated pattern design to create a low volume capacitor. A YAG laser was used to ablate resistance lines in the film resulting in a sinuous, square pattern on a VOGN/Ni coated alumina substrate and utilizing a gel electrolyte to create the EDLC.
24
Agrawal, Richa. "Hybrid Electrochemical Capacitors: Materials, Optimization, and Miniaturization". FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3680.
Testo completoAbstract (sommario):
With the ever-advancing technology, there is an incessant need for reliable electrochemical energy storage (EES) components that can provide desired energy and power. At the forefront of EES systems are electrochemical capacitors (ECs), also known as supercapacitors that typically have higher power and superior cycle longevity but lower energy densities than their battery counterparts. One of the routes to achieve higher energy density for ECs is using the hybrid EC configuration, which typically utilizes a redox electrode coupled with a counter double-layer type electrode.
In this dissertation, both scale-up (coin-cell type) as well as scale-down (on-chip miniaturized) hybrid ECs were designed, constructed and evaluated. The first part of the dissertation comprised material identification, syntheses, and electrochemical analyses. Lithium titanate-anatase titanium oxide (Li4Ti5O12-TiO2) composites were synthesized via electrostatic spray deposition (ESD) and characterized in both half-cell and full-cell assembly against lithium and nanostructured carbon based counter electrodes, respectively. The second redox type material studied for hybrid electrochemical capacitors was ESD derived manganese oxide (MnOx). The MnOx electrodes exhibited a high gravimetric capacitance of 225F g-1 in aqueous media. Further improvement in the rate handling of the MnOx electrodes was achieved by using CNT additives. The MnOx-CNT composites were tested in full-cell assembly against activated carbon counter electrodes and tested for different anode and cathode mass ratios in order to achieve the best energy-power tradeoff, which was the second major goal of the dissertation. The optimized hybrid capacitor was able to deliver a high specific energy density of 30.3 Wh kg-1 and a maximal power density of 4kW kg-1. The last part of the dissertation focused on a scale-down miniaturized hybrid microsupercapacitor; an interdigitated electrode design was adopted in order to shorten the ion-transport pathway, and MnOx and reduced graphene oxide (rGO) were chosen as the redox and double layer components, respectively. The hybrid microsupercapacitor was able to deliver a high stack energy density of 1.02 mWh cm-3 and a maximal stack power density of 3.44 W cm-3, both of which are comparable with thin-film batteries and commercial supercapacitor in terms of volumetric energy and power densities.
25
Villamil, Susan Simmons. "Impedance characteristics and grain boundary effects in titanate-based multilayer ceramic capacitors". Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/94507.
Testo completoAbstract (sommario):
The major goal of this study was to gain a better understanding of the effects that grain boundaries have on conduction in multilayer ceramic (MLC) capacitors. Electrical measurements were made so that current-voltage curves and impedance plots could be constructed.
It was found that the current-voltage curves of new COG and X7R multilayer ceramic capacitors are both ohmic at low voltages and super-ohmic at intermediate voltages. Ohmic behavior prevails at high voltages for both types. Such behavior can be attributed to grain boundaries.
Grain boundary resistance was clearly exhibited by X7R-type density blanks and one commercially manufactured type of X7R MLC capacitor, while the NPO density blank and two different values of Z5U multilayer ceramic capacitors, each from a different manufacturer, indicated the possibility of grain boundary resistance. All of the samples that were tested showed possible, if not probable, evidence of grain resistance. Only the Z5U-type density blank showed a resistance contribution from the bulk-electrode interfaces.
A model for the grain boundary potential barrier height was developed. It was found that barrier height reduction occurs for small grain sizes due to depletion of the grain, and for increased grain curvature. Dopant effects are also responsible for barrier height reduction.
These results, and the related modelling, indicate that grain boundary contributions to titanate-based ceramic resistance can vary widely from sample to sample, since there are so many material dependent variables involved. Such measurements as those described here can help clarify how grain boundaries and other factors contribute to ceramic resistance.M.S.
26
Schunke, J. N. "Intrinsic degradation mechanisms of barium titanate based multilayer ceramic capacitors". Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/53086.
Testo completoAbstract (sommario):
A study was conducted into the intrinsic degradation behavior of X7R and Z5U capacitors. The major goals of this research were:
1) to determine current-voltage, activation energy and leakage current characteristics for such capacitors.
2) to investigate how these characteristics change with degradation;
3) to investigate possible correlations between observed behavior and capacitor microstructure or composition.
Examination of capacitor microstructures revealed large differences in grain morphology and electrode spacings. The development of a color gradient between positive and negative electrodes with. degradation was observed in one type of capacitor.
Compositional studies using EDAX, AUGER, and microprobe analyses failed to detect gradients in dielectric composition in degraded capacitors indicating that gradients are less than 0.1 atomic percent. Current-voltage studies showed a 3/2 power dependance, at voltages above one volt for X7R capacitors indicating space charge limited current. This dependance was attributed to point emission from electrode protuberances. The 3/2 dependance was observed to shift to a square law behavior with degradation. This change was attributed to a increase in conductivity of the dielectric near the cathode, blunting the effect of electrode protuberances. Z5U capacitors were found to have ohmic behavior. No Schottky or Poole Frenkel currents were observed.
Degradation studies were carried out on capacitors at 2 to 8 times the rated voltage, and at temperatures from 100 to 1500℃. Leakage currents in actively degrading capacitors were observed to rise exponentially with time. This rise was accompanied by a gradual decrease in activation energy. A model is proposed to explain the observed current vs degradation behavior.Master of Science
27
Wade, Timothy Lawrence. "High power carbon based supercapacitors /". Connect to thesis, 2006. http://repository.unimelb.edu.au/10187/439.
Testo completoAbstract (sommario):
Energy storage devices are generally evaluated on two main requirements; power and energy. In supercapacitors these two performance criteria are altered by the capacitance, resistance and voltage. (For complete abstract open document)
28
Anderson, Matthew Wilamowski Bogdan M. "Wide range tunable transconductance filters". Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SPRING/Electrical_and_Computer_Engineering/Thesis/Anderson_William_22.pdf.
Testo completo
29
Uz, Eda. "Design And Implementation Of Thyristor Switched Shunt Capacitors". Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611616/index.pdf.
Testo completoAbstract (sommario):
This research work deals with the analysis, design and implementation of thyristor switched plain capacitor banks and thyristor switched shunt filter banks. Performances of various thyristor switched capacitor (TSC) topologies are also investigated by simulations. The theoretical findings have been verified by carrying out experimental work on two prototypes implemented within the scope of this research work, one is a wye-connected laboratory prototype and the other is a delta-connected application prototype integrated to some of the SVCs existing in Turkish Coal Enterprise s Plants. The advantages of back-to-back connected thyristor switches over conventional electromechanical contactors are also made clear by conducting an intensive experimental work in the laboratory. A good correlation have been obtained between theoretical and experimental results.
30
Sundberg, Nicklas. "Efficiency Improvements with Super Capacitors in Mechatronic Systems". Thesis, KTH, Maskinkonstruktion (Inst.), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-100714.
Testo completoAbstract (sommario):
The production industry is getting more and more automated and that implies higher energy consumption. With the increasing awareness of the earth limited resources and the increasing energy prices, energy conservation grows in relevance, both due to cost reduction and environmental benefits. One way to conserve energy is to optimize the energy usage within the business and reduce the losses. Regenerative braking is already in use today for this purpose in vehicles. The aim of this thesis is to investigate how regenerative braking can be fitted into the production industry and what adaptations need to be made. This thesis is based on an earlier study that has set up a mathematical model for energy regeneration in mechatronic systems and the goal of this thesis is to build a test rig and verify the correctness of these models. One suggested improvement to the automotive systems are the introduction of super capacitors as a secondary energy source because they can charge more rapidly compared to batteries which is required during the expected fast accelerations. In the performed tests an efficiency improvement of 10 % was shown. The earlier study however suggests an efficiency rate of 60% but those models do not include frictional nor electrical losses. The results are complemented by a discussion were a number of changes to the design is proposed. A different motor control system would significantly enhance the rig and a result more like the expected can be achieved.Det ökade antalet elektromekaniska maskiner i industriella tillämpningar medför en ökad energianvändning. Då våra begränsade resurser mer och mer belyses i media och med stigande energipriser ökar intresset hos företagen för att minska sin energianvändning, dels för att reducera sina kostnader och dels för att minska den miljöbelastning slutprodukten medför. Ett sätt att göra detta är att minska energiförlusterna inom sin produktion. Regenerativ bromsning är en teknik som används i fordon idag och kan användas för detta syfte. Detta arbete ska undersöka hur sådan teknik kan användas i tillverkningsindustrin och vilka förändringar som måste göras. Ett tidigare arbete har satt upp teoretiska modeller för detta och det här arbetet syftar till att bygga en tesrigg för att praktiskt undersöka modellernas korrekthet. En förbättring mot det system som används i dagens bilar är att införa superkondensatorer som parallell energikälla då dessa är snabbare på att lagra energi än ett batteri och därför passar bättre för de snabba accelerationer och retardationer som förekommer i industriprocesser. De genomförda testerna påverkades negativt av vissa begränsningar i hårdvaran men resultatet visar ändå att regenereringen kan återföra 10 % av energin till kondensatorerna, det motsvarar däremot inte den mängden som de tidigare uppsatta modellerna förutspådde. Orsakerna är olika förluster i systemet som inte modellerna tar hänsyn till. De viktigaste förlustfaktorerna beror på friktion och styrningen av elektroniken. Med en annan typ av motorstyrning kan förlusterna minskas och ett resultat mer likt det förväntade uppnås.
31
Prasertchoung, Sanwarit. "Pulse switching and scaling effects in ferroelectric capacitors". College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/4248.
Testo completoAbstract (sommario):
Thesis (Ph. D.) -- University of Maryland, College Park, 2006.Thesis research directed by: Material Science and Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
32
Bhat, Shreyas. "Salinity (conductivity) sensor based on parallel plate capacitors". [Tampa, Fla] : University of South Florida, 2005. http://purl.fcla.edu/usf/dc/et/SFE0001381.
Testo completo
33
Lao, Zhuo Jin. "Metal oxides as electrode materials for electrochemical capacitors". Access electronically, 2006. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060726.101327/index.html.
Testo completo
34
Alvi, Farah. "Synthesis and Characterization of Nanocomposites for Electrochemical Capacitors". Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/3948.
Testo completoAbstract (sommario):
Presently there are deep concerns over the environmental consequences and the consumption of non-renewable energy sources, with the accelerated greenhouse effect, triggered enormous interest in the use of renewable energy sources e.g., solar, hydropower, wind and geothermal. However the intermittent nature of harvesting renewable energy sources has recently gained considerable attention in the alternative reliable, cost effective, and environmentally friendly energy storage devices. The supercapacitor and lithium ion batteries are considered more efficient electrical energy storage devices than conventional energy storage systems.
Both devices have many useful and important applications; they could be an excellent source for high power and high energy density, especially in portable electronic devices and Electrical Vehicles (EVs) or Hybrid Electrical Vehicles (HEVs). In order to make the efficient usage of these stationary energy storage devices, state of the art research on new and advanced electrode materials is highly needed. The aim of this dissertation is to investigate the scope of graphene/metal oxide-conducting polymer nanocomposites electrodes for light weight, high power density and wider voltage window supercapacitor devices.
The facile chemical polymerization approach was used to synthesize the aromatic and heterocyclic conducting polymer nanocomposites. For aromatic nanocomposites, several materials were synthesized includes ZnO-PANI, ZnO/G-PANI,RuO2-PANI and G-PANI. Subsequently these materials have been characterized by physical, structural techniques e.g Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Xray-Diffraction (XRD), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). In addition to material characterization the prepared material was also characterized by electrochemical measurements using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chrono potentiometry for supercapacitor electrodes. Since graphene is a two-dimensional single-atom-thick sp2 hybridized carbon structure due to its extraordinary characteristic, high electrical conductivity, chemical stability and large theoretical surface area (over 2600 m2 g−1) has gained immense interest in the future generation of renewable energy devices. Therefore, among all aromatic based nanocomposites, the Graphene-Polyaniline (G-PANI) rendered promisingly high specific capacitance around 440 F/g with the excellent cyclic stability. The higher specific capacitance of G-PANI might be due to the high conductivity and superior electrochemical properties of graphene in G-PANI nanocomposites.
However, besides the G-PANI, other aromatic nanocomposites e.g., RuO2-PANI, ZnO-PANI and G/ZnO-PANI also showed the potential of low cost and flexible supercapacitor electrodes with the reasonably good specific capacitance as 360 F/g, 300 F/g, and 275 F/g. We have further investigated the role of conductivity by adding different amount of graphene in G-PANI nanocomposites to optimize device performance with the specific capacitance and columbic efficiency of 440 F/g and 90% respectively.Further the other important parameters, relate with the electrode thickness, type of electrolytes, concentration of electrolytes and the effect of the solvent has also been studied to achieve the overall performance and reliability of the device. Moreover, in order to have the comprehensive study of conducting polymer besides the aromatic conducting polymer the heterocyclic polymers e.g., polythiophene and poly (3, 4-ethylenedioxythiophenes) (PEDOT) nanocomposites were studied at length to evaluate their role for the cost effective, large surface area and flexible green energy storage devices and has shown great prospects for commercial application. Therefore, G-Cps nanocomposites have proved to be a promising electrode material choice to facilitate the ionic diffusion and contact of the electrolytes to improve the specific capacitance and performance of the device.
35
Ali, Richard A. "Reliability and characterization of high voltage power capacitors". Thesis, Monterey, California: Naval Postgraduate School, 2014. http://hdl.handle.net/10945/41346.
Testo completoAbstract (sommario):
Approved for public release; distribution is unlimited.Alternative energy products are an increasingly common sight on military bases in the United States. Energy product reliability affects the sustainability and cost-effectiveness of these systems, which must be tested by outside entities to ensure quality. The purpose of this thesis is to perform component level reliability testing on a high voltage power capacitor used in an electrical vehicle solar charging system. A component level characterization was performed to better understand the physical attributes of these capacitors. This investigation identified the expected component lifetime and conditions in which this component will become less reliable. Results are compared to those published by the manufacturer.
36
Bishay, A. G. "Capacitance of planar capacitors and discontinuous metal films". Thesis, City University London, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354899.
Testo completo
37
Haj, Hassan Nooshin L. "Advanced materials for lithium batteries and electrochemical capacitors". Thesis, Loughborough University, 2009. https://dspace.lboro.ac.uk/2134/15179.
Testo completoAbstract (sommario):
This thesis describes research carried out in the area of materials electrochemistry. The general goal was to develop and test advanced materials that might improve the performance of real-world electrochemical systems. Particular systems of interest were lithium thionyl chloride batteries, lithium sulphur batteries, and carbon-based electrochemical capacitors. Developments are reported in all three cases. Materials electrochemistry is an interdisciplinary field that investigates the relationship between the structure, properties, processing and electrochemical performance of novel materials. These may be electrodes, solutions, or combinations of both. Besides conventional electrochemical measurements, materials electrochemistry also includes elements of process development and engineering. In the present work, much effort was expended on the formulation, mixing, extrusion and curing of particulate carbon electrodes. In particular, numerous large-scale screening programs were carried out to examine the effects of multiple independent variables on battery performance. Although this required much effort to set up, the payoff was that it allowed improved processing parameters, and materials of advanced performance to be determined with a high level of confidence. Considerable effort was also expended on the development of apparatus for handling air-sensitive battery solvents, such as thionyl chloride. Amongst the achievements of the present work are: (i) the successful reformulation of the manufacturing solvent for commercial lithium battery electrodes, to halve the quantity of isopropyl alcohol used. In the future this will allow the manufacturing process to continue within UKIEU regulations. (ii) The improvement of the mechanical strength and electrochemical capacity of thick-film carbon electrodes by adding conducting carbon fibre. (iii) The development of an easy-to-implement test that accurately predicts the performance of lithium thionyl chloride battery electrodes. (iv) The development of a novel electrolyte solution for lithium sulphur batteries (using a sulfolane/ethylene carbonate mixture). (v) The discovery that this solution can be gelled with PVDF, and finally (vi) the discovery that some carbon blacks out-perform activated carbon in thick-film electrodes for electrochemical capacitors.
38
Gupta, Sahil. "Structure-Property Relationships in Polymers for Dielectric Capacitors". University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1395682393.
Testo completo
39
DeLibero, Michael L. "MEASUREMENT CIRCUITS AND MODELING TECHNIQUES FOR TITANIUM CAPACITORS". Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1438640389.
Testo completo
40
Mussi, Toschi Vitoria. "Lead-free ferroelectric ceramics for multilayer ceramic capacitors". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC089.
Testo completoAbstract (sommario):
De nos jours, la consommation des condensateurs céramiques multicouches (MLCCs) augmente en raison de leur efficacité et leur fiabilité. La miniaturisation résultant dans une plus grande dissipation volumique de chaleur et les nouvelles applications demandent des MLCCs qui peuvent travailler de 300 à 350°C, au-delà des limites actuelles de 200 – 250°C. De plus, les exigences environnementales augmentent également avec les réglementations REACH et RoHS qui interdisent l'utilisation du plomb en Europe. Il est donc impératif de créer des nouveaux matériaux sans plomb capables de répondre aux nouvelles attentes des MLCC.Cependant, la compatibilité avec les méthodes de production industrielle, ainsi que les prix du marché sont des limites importantes. Trois familles de matériaux sans plomb ont été examinées : celle du BaTiO3 (BT), du K0.5Na0.5NbO3 et du Na0.5Bi0.5TiO3 (NBT). Le NBT-BT à la MPB (6 % BT) a été choisi comme matériau diélectrique de base. Plusieurs méthodes et paramètres de synthèse ont ensuite été étudiés pour déterminer les meilleures conditions de synthèse. La synthèse à l'état solide et le frittage traditionnel ont été choisis pour les échantillons en massif et le coulage en bande a été choisi pour les couches. Pour éviter l'évaporation des espèces volatiles, le frittage a été effectué en couvrant le NBT-BT par une poudre de ZrO2. Tous les échantillons présentaient des phases secondaires contenant du Ba (Ba2TiO4 et Ba2Ti9O20) en raison de l'évaporation du Na pendant le frittage. Un effet de peau créé par la coexistence des phases tétragonale, rhomboédrique et cubique a également été observé, lié à la concentration locale de Ba dans le réseau cristallin du NBT. Les effets des paramètres de synthèse et la stœchiométrie des réactifs sur les propriétés diélectriques, la résistance d'isolement et la séparation des phases ont été analysés. La stœchiométrie nominale Na0.44Bi0.48Ba0.06TiO3 était la plus appropriée pour les MLCC en raison de sa résistance d'isolement élevée, de ses faibles pertes diélectriques et de sa stabilité de la permittivité en température. La présence de phases secondaires est initialement bénéfique en raison de l'élimination des lacunes d'oxygène. Au-delà d'une fraction volumique critique (2.5 à 3.0 %) et d'une taille de grain moyenne critique (0.9 à 3.0 m2), la tendance s'inverse en raison de la nature conductrice des phases secondaires.Pour atteindre la fraction volumique et la taille de grain critiques, un agent dispersant a été utilisé lors du broyage dans la jarre de YSZ, avec du MEK et de l'éthanol comme solvants, et sans sécher les réactifs avant la pesée. Enfin, la relaxation des contraintes a été réalisée à 400°C pendant 3 heures. Trois modèles ont été utilisés pour expliquer la dispersion des propriétés diélectriques en fréquence : le modèle de Maxwell-Wagner, le modèle de Nyquist et la loi de Curie-Weiss modifiée. Les incompatibilités entre les propriétés diélectriques du NBT-BT rapportées dans la littérature ont ensuite été analysées soulignant l'importance d'avoir des méthodes de synthèse et de mesure strictes. Les trois principaux facteurs affectant les propriétés diélectriques induisant ces incompatibilités étaient la stœchiométrie, la méthode de métallisation et la fixation des fils électriques à l'aide de la laque d'argent. Des pertes diélectriques croissantes à haute température a aussi été observée après chaque cycle thermique dépassant les 300°C, indiquant une dégradation thermique des échantillons.Enfin, les monocouches céramiques ont montré une faible densité (62%) après frittage, limitant la plage de température correspondant aux spécifications d'Exxelia. Cependant, en utilisant un pressage des couches avant frittage, l'échantillon multicouche fritté présentait une densité élevée (89%). Une mesure des propriétés diélectriques doit être effectuée sur cet échantillon multicouche synthétisé, afin de déterminer sa compatibilité avec les spécifications d’ExxeliaMLCC consumption is today increasing due to their high efficiency, reliability and frequency characteristics. MLCCs that can work from 300 to 350°C are required both for miniaturization, resulting in greater volume heat dissipation and for new applications. Moreover, environmental requirements are also increasing, the REACH and RoHS regulations prohibiting the use of lead in Europe. It is imperative to create new lead-free materials that are able to meet those requirements.However, the compatibility with the production methods, price, and market are important industrial limitations that need to be considered.Three families of lead-free materials were examined: BaTiO3-based, K0.5Na0.5NbO3-based and Na0.5Bi0.5TiO3-based materials. NBT-BT at the morphotropic phase boundary (6% BT) was chosen as the base dielectric material.Several synthesis methods and parameters were studied to determine the best synthesis conditions. Solid-state synthesis and traditional sintering were chosen for the bulk samples and tape casting was chosen for the layer samples preparation. Sintering was done under ZrO2 powder to prevent the evaporation of volatile species.All samples had secondary Ba-containing phases (Ba2TiO4 and Ba2Ti9O20) formed because of the evaporation of Na during sintering. A skin-effect was observed due to a phase coexistence (tetragonal, rhombohedral, and cubic) due to the local concentration of Ba in the NBT lattice.The effects of the synthesis parameters and the stoichiometry of the reactants on dielectric properties, insulation resistance, and phase separation were analysed.The Na0.44Bi0.48Ba0.06TiO3 nominal stoichiometry was the most suitable for the MLCCs due to its high insulation resistance, low dielectric losses, and stability of permittivity in temperature.The phase separation was initially beneficial, due to the resulting elimination of oxygen vacancies. Above a critical volume fraction (2.5 to 3.0%) and a critical mean surface area (0.9 to 3.0 m2), the trend was reversed due to the conductive nature of the secondary phases.To achieve the critical volume fraction and surface area of the secondary phases, a dispersing agent was used during ball-milling in YSZ jar, with MEK and ethanol as solvents, and without drying the reactants prior to weighing. Finally, a strain relaxation was done at 400°C for 3 hours.Three models explained the frequency dispersion of the dielectric properties: the Maxwell-Wagner model, the Nyquist plot and the modified Curie-Weiss law.Incompatibilities between the dielectric properties of NBT-BT reported in the literature were then analysed, showing the importance of maintaining strict synthesis and measurement methods. The three main factors affected the dielectric properties, creating these incompatibilities in the bulk samples. There were the stoichiometry, the metallization method, and the fixing of the electrical leads using silver paste.An increase of the high-temperature dielectric losses after each thermal cycle reaching more than 300°C was observed, indicating a thermal degradation of the material.Finally, the sintered ceramic monolayers showed a low density (62%), limiting the temperature range corresponding to Exxelia’s specifications. However, after pressing the layers together before sintering, the sintered multilayer sample showed a high density (89%). Dielectric property measurement should be carried out for these synthesized multilayers
41
Krishnamurthy, Kumar. "Supercritical extraction of binder from multilayer ceramic capacitors". Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/5658.
Testo completoAbstract (sommario):
Thesis (M.S.)--University of Missouri-Columbia, 2008.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 12, 2009) Vita. Includes bibliographical references.
42
Adams, Timothy B. "Barrier layer capacitors based on CaCu₃Ti₄O₁₂". Thesis, University of Sheffield, 2006. http://etheses.whiterose.ac.uk/10520/.
Testo completoAbstract (sommario):
Calcium-Copper-Titanate (CCTO) is one of a class of non-ferroelectric, highly tilted Perovskite-structured oxides. Theoretical values of permittivity for these materials are low and fairly typical for non-ferroelectrics, yet these materials received considerable attention when reports of extremely high permittivity (in excess of 10,000) emerged, with one study on CCTO published in Science that attempted to assign the unusual behaviour to an as yet unknown exotic polarisation mechanism. This thesis proves that the high permittivity is actually extrinsic in origin and originates from a barrier layer capacitance effect; the measured values for intrinsic permittivity for CCTO and related ceramics was found to be low and comparable to theoretical values.
43
Orozco, montes Maileth. "Implémentation d'un générateur de nanoparticules en phase gazeuse fondé sur la pulvérisation cathodique magnétron pour la synthèse de films minces nanocomposities céramique/nanoparticules métalliques". Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0082/document.
Testo completoAbstract (sommario):
Ces travaux de thèse portent sur l’étude d’un générateur de nanoparticules (NPs) en phase gazeuse basé sur la pulvérisation cathodique magnétron. La mise en oeuvre d’un spectromètre d’émission optique et d’une microbalance à quartz a permis d’observer l’influence des paramètres du procédé (nature et débit des gaz, courant cathodique, configuration magnétique) sur les espèces présentes dans le plasma et la vitesse de dépôt des NPs. Ceci a conduit à une meilleure compréhension du procédé et à l’établissement d’un point de fonctionnement. Des analyses par microscopique électronique en transmission (MET) ont mis en évidence des NPs d’argent cristallisées en vol dont la taille augmente (de 2,5 ± 0,5 nm à 5,2 ± 0,5 nm de diamètre) avec la longueur d’agrégation. L’association de cette source à un réacteur de pulvérisation magnétron conventionnelle a permis la synthèse de nanocomposites constitués de nanoparticules métalliques (Cu ou Ag) dans une matrice céramique diélectrique amorphe et transparente (nitrure ou oxyde d’aluminium). Un décalage de la Résonance Plasmon de Surface (RPS) vers le rouge a été observé avec l’augmentation de la permittivité de la matrice ainsi qu’un élargissement de la RPS avec la diminution de la taille des NPs. Enfin, les propriétés électriques des nanocomposites ont été étudiés au sein de capacités de type Métal/Isolant/Métal (MIM) permettant une modulation de la permittivité avec le taux de dopage en NPs d’argent (5% et 10% vol.)This thesis is dedicated to the study of free nanoparticles (NPs) source based on magnetron sputtering. Setting up an optical emission spectrometer and a quartz microbalance allowed to observe the influence of the process parameters (gas composition and flow rate, cathodic current, magnetic configuration) on the plasma species and the NPs deposition rate. This lead to a better understanding of the process and the establishment of a process operating windows. Transmission Electron Microscopy (TEM) analysis revealed crystallized silver NPs whose size increased (from 2.5 ± 0.5 nm to 5.2 ± 0.5 nm in diameter) when the aggregation length increased. The free NPs source coupled to a conventional magnetron sputtering chamber allowed the deposition of nanocomposites thin films consisting of metallic NPs (Cu ou Ag) embedded in dielectric transparent amorphous matrix (aluminum nitride or oxide). A red shift of the Surface Plasmon Resonance (SPR) was observed with the increase of the matrix permittivity value. A broadening of the SPR with the decrease of the NPs size was also evidenced. Finally, the electrical properties of the nanocomposites have been studied by means of a Metal/Insulator/Metal capacitor pointing out a modulation of the permittivity with the silver NPs content (5% and 10% vol.)
44
Chan, Siu-wo. "Design, control and application of battery-ultracapacitor hybrid systems". Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B38816660.
Testo completo
45
Yue, Jireh Jon-Kai. "Study of high K polymers for integral capacitor applications". Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/19036.
Testo completo
46
Pak, Hee Chul. "Two distributed capacitance models /". Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
Testo completo
47
Islas, Michael E. "Efficiency improvement techniques for high voltage capacitor carging [sic] methods". Orlando, Fla. : University of Central Florida, 2009. http://purl.fcla.edu/fcla/etd/CFE0002899.
Testo completo
48
Imam, Afroz M. "Condition Monitoring of Electrolytic Capacitors for Power Electronics Applications". Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14472.
Testo completoAbstract (sommario):
The objective of this research is to advance the field of condition monitoring of electrolytic capacitors used in power electronics circuits.
The construction process of an electrolytic capacitor is presented. Descriptions of various kinds of faults that can occur in an electrolytic capacitor are discussed. The methods available to detect electrolytic capacitor faults are discussed. The effects of the capacitor faults on the capacitor voltage and current waveforms are investigated through experiments. It is also experimentally demonstrated that faults in the capacitor can be detected by monitoring the capacitor voltage and current.
Various ESR estimation based detection techniques available to detect capacitor failures in power electronics circuits are reviewed. Three algorithms are proposed to track and detect capacitor failures: an FFT based algorithm, a system modeling based detection scheme, and finally a parameter estimation based algorithm. The parameter estimation based algorithm is a low-cost real-time scheme, and it is inexpensive to implement.
Finally, a detailed study is carried out to understand the failure mechanism of an electrolytic capacitor due to inrush current.
49
Wang, Yushu. "Thin-film trench capacitors for silicon and organic packages". Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42741.
Testo completoAbstract (sommario):
The continuous trend towards mega-functional, high-performance and ultra-miniaturized system has been driving the need for advances in novel materials with superior properties leading to thin components, high-density interconnect substrates and interconnections. Power supply and management is becoming a critical bottleneck for the advances in such mega-functional systems because power components do not scale down with the rest of the system resulting in bulky and stand-alone power modules. Amongst the power components, thin film capacitors are considered the most challenging to integrate because of several manufacturability concerns. The challenges are related to process compatibility of high permittivity dielectrics with substrates and high surface area electrodes, yield, leakage and losses. This thesis focuses on novel thin film capacitor technologies that address some of these critical challenges.Thesis advisor has approved the addition of errata to this item. The abstract text in the metadata record has been modified to match the document text.
50
Zubieta, Bernal Luis Eduardo. "Characterization of double-layer capacitors for power electronics applications". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ28861.pdf.
Testo completo