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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Entwicklung von Werkzeugen zur automatisierten Traktionsspeicherdimensionierung auf dieselelektrisch angetriebenen Schienenfahrzeugen

Melzer, Michael 30 July 2014 (has links) (PDF)
Diese Arbeit befasst sich mit der Implementierung eines Energiespeichersystems in ein dieselelektrisches Schienenfahrzeug. Ziel der Arbeit ist es mit einem automatisierten Ansatz die besten Parameter für das Energiespeichersystem zu finden. Um die geeignetsten Parameter zu bestimmen, wurde eine Optimierung basierend auf genetischen Algorithmen verwendet. Neben der Charakteristik des Energiespeichersystems wird auch dessen Betriebsstrategie untersucht und optimiert. Der Fahrstil genau wie die Leistung des Dieselmotors werden ebenfalls variiert, um die Ergebnisse der Optimierung mit und ohne Energiespeichersystem zu vergleichen. / This work deals with an implementation of an energy storage system in a diesel electric driven rail vehicle. The aim of this work is an automatic approach to find the best parameters for an energy storage system. To find the best fitting parameters an optimization based on genetic algorithms is used. Beside the characteristics of the energy storage system as well the strategy to operate it is investigated and optimized. The driving style as well as the power of the internal combustion engine are varied in order to compare the solution of the optimization with and without energy storage systems.
122

Design, Development and Applications R & D on Substrate-Integrated Lead-Carbon Hybrid Ultracapacitors

Banerjee, Anjan January 2014 (has links) (PDF)
Electrochemical capacitors or supercapacitors or ultracapacitors are potential energy storage devices that could help bringing major advances in future energy storage applications. Unlike batteries that store energy in chemical reactants capable of generating charge, electrochemical capacitors store energy directly through charge separation. Most electrochemical capacitors rely on carbon-based structures utilizing electrical double-layer capacitance effect. By contrast, a pseudocapacitor relies on charge stored due to fast faradaic charge-transfer processes with surface atoms. A combination of faradaic and non-faradaic components would generate hybrid electrochemical capacitors or hybrid ultracapacitors that attain high capacitance for pulse power and sustained energy. This thesis comprises studies pertaining to design, development and applications R&D on substrate-integrated lead-carbon hybrid ultracapacitors. The thesis comprises ten chapters. Chapter 1 is a brief introduction on essentials of electrochemical capacitors explaining their operating principles, classification and applications. Chapter 2 describes studies on materials for electrical double-layer capacitors. Activated carbons are the most common materials for electrical double-layer capacitors. Various activated carbon samples are screened as suitable materials for electrical double-layer capacitor followed by their optimization under varying experimental conditions to form the negative plate in the substrate-integrated lead-carbon hybrid ultracapacitor. Chapter 3 deals with the studies on design and development of 2 V substrate-integrated lead-carbon hybrid ultracapacitors with flooded, absorbent-glass-mat and silica-gel sulfuric acid electrolyte configurations. Lead-carbon hybrid ultracapacitors comprise substrate-integrated lead dioxide sheets as positive plates and high surface-area-carbon-coated graphite-sheets as negative plates. Operating principle for 2 V lead-carbon hybrid ultracapacitors is explained and optimization of their operating conditions along with their electrochemical performance is studied. Chapter 4 is a study on the integration of 2 V substrate-integrated lead-carbon hybrid ultracapacitors to 12 V devices. 12 V substrate-integrated lead-carbon hybrid ultracapacitors with flooded, absorbent-glass-mat and silica gel sulfuric acid electrolyte are developed by connecting six 2 V cells in series. These hybrid ultracapacitors exhibit high power-density values and excellent cycle-life. The problem of uneven performance among the six 2 V cells in the 12 V hybrid ultracapacitors is addressed and resolved by applying voltage-management cell-balancing circuitry. Chapter 5 details the studies on kilo-Farad range 12 V substrate-integrated lead-carbon hybrid ultracapacitors. The hybrid ultracapacitors are performance tested through a standard protocol. Thermal runaway in these hybrid ultracapacitors at high load currents is studied by thermal imaging. Studies on performance comparison between 12 V lead-carbon hybrid ultracapacitors with substrate-integrated and conventional pasted-positive plates are presented in Chapter 6. For substrate-integrated-positive plate lead-carbon hybrid ultracapacitors, capacitance and energy-density values are lower but power-density values are higher than pasted-positive plate configuration due to their shorter response-time. Accordingly, internal resistance values are lower for substrate-integrated lead-carbon hybrid ultracapacitors. Both types of lead-carbon hybrid ultracapacitors exhibit similar faradaic efficiency and cycle-life in excess of 100,000 pulse charge/discharge cycles with only a nominal loss in their capacitance values. Chapter 7 is a study on the design and development of low-cost substrate-integrated lead-carbon hybrid ultracapacitors using poly-aniline organic metal. The hybrid ultracapacitor employs flexible exfoliated graphite sheets as negative plate current-collectors, which are coated with a thin layer of poly-aniline to provide good adhesivity to activated carbon layer and good substrate-conductivity. These ultracapacitors are estimated to cost about 4 US$/Wh as compared to 20-30 US$/Wh for presently available commercial ultracapacitors. In Chapter 8, an application R&D study on the suitability of a substrate-integrated lead-carbon hybrid ultracapacitor bank in powering medical gadgets is described. A practical application that provides 30 W power back-up to medical gadgets for use in grid-power-deficient rural areas is presented. Chapter 9 is another application R&D study in realizing a photovoltaic stand-alone lighting system using substrate-integrated lead-carbon hybrid ultracapacitors. At present, harnessing solar electricity generated through photovoltaic cells with lead-acid batteries remains the most compelling option. But lead-acid batteries have encountered problems in photovoltaic installations, mainly due to their premature failure. To circumvent this problem, substrate-integrated lead-carbon hybrid ultracapacitors are developed for solar energy storage for a lighting application. The last Chapter of the thesis comprises field studies on substrate-integrated lead-carbon hybrid ultracapacitors. In the study, hybrid ultracapacitors are installed for lighting applications for field tests. Grid-power chargers and mechanical dynamos are introduced as fast-charging tools for hybrid ultracapacitors. It is hoped that the studies presented in this thesis would constitute a worthwhile contribution to science and technology of electrochemical capacitors. Considering the technology need, availability, safety and cost, substrate-integrated lead-carbon hybrid ultracapacitors are set to play a seminal role in future energy storage and management.
123

Étude du phénomène d'électrisation par écoulement : impact d'un champ électrique externe sur la double couche électrique / Study of the flow electrification phenomenon : impact of an external electric field on the electrical double layer

Leblanc, Paul 01 December 2015 (has links)
A l'interface solide-liquide, des réactions physicochimiques conduisent à polariser l'interface et à former la double couche électrique (DCE). La circulation du liquide transporte une partie des charges électriques de la DCE et conduit au phénomène d'électrisation par écoulement. Dans les transformateurs de puissance, constitués, entre autres, d'huile minérale et de carton d'isolement, le phénomène d'électrisation est suspecté d'être à l'origine de certaines défaillances et accidents. Dans cette problématique de risque, de nombreuses études ont été menées et ont permis de mettre en évidence l'influence de paramètres significatifs : nature des matériaux, humidité des matériaux, géométrie et vitesse de l'écoulement, température. Peu d'études se sont concentrées sur l'influence du champ électrique, en particulier les champs continus (DC). Même si le champ électrique généré dans les équipements de puissance est principalement alternatif (AC), il n'en est pas moins vrai que des champs électriques continus (DC) résiduels peuvent être présents, en particulier dans les dispositifs H.V.D.C (High Voltage Direct Current). L'objet du travail s'inscrit dans ce contexte et a pour but, dans une approche à la fois expérimentale et numérique, d'apporter des éléments de réponse sur le développement et le transport des charges de la double couche électrique sous contrainte de champ électrique externe. / At the solid-liquid interface, physicochemical reactions lead to the polarization of the interface and to the formation of an electrical double layer (EDL). The process of flow electrification is due to the convection of part of the electrical charges located in the EDL. In power transformers within which mineral oil and pressboard are commonly used for cooling and electrical insulation, a flow electrification phenomenon is suspected to be responsible of failures. In this hazard assessment problematic, many studies have been made and allowed identifying the influence of significant parameters: nature of materials, moisture level of materials, flow geometry and velocity, temperature. Few studies have focused on the influence of the electric filed, particularly the continuous electric fields (DC). Even though the electric field generated within power transformers is mainly alternating (AC), it is nonetheless true that residual DC electric fields may be detected (e.g. High Voltage Direct Current appartus). This present work fits in this context and aims at providing, both through an experimental and numerical approach, some answers on the development and the transport of charges from the electrical double layer under external electric field stresses.
124

Multi-dimensional carbonaceous composites for electrode applications

Lin, J.-F. (Jhih-Fong) 15 June 2015 (has links)
Abstract The objective of this thesis is to demonstrate multi-dimensional carbon nanotube (CNT) structures in combination with various active materials in order to evaluate their performance in electrode applications such as cold emitters, electric double-layer capacitors (EDLC), and electrochemical sensor/catalyst devices. As the host materials for other active materials, the construction of multi-dimensional CNT nanostructures in this thesis is achieved by two different approaches. In the first, direct growth of 3-dimensional carbon nanostructures by catalytic chemical deposition to produce filamentary carbon as well as vertically aligned forests was applied. The second route that was utilized encompassed the immobilization of CNTs from dispersions to form 2-dimensional surface coatings as well as self-supporting porous buckypapers. Carbonaceous nanocomposites of the active materials are obtained by a number of different methods such as (i) growing nanotubes and filamentous structures on porous Ni catalyst structures, (ii) impregnating CNTs with organic receptor molecules or with Pd nanoparticles, (iii) plating and replacing Cu with Pd on the nanotubes by chemical and galvanic reactions, (iv) annealing W evaporated on CNTs to form CNT-WC composites in solid-solid reactions and (v) reacting S vapor with W coated on CNTs to synthesize CNT-WS2 edge-on lamellar structures of the dichalcogenide in the vertically aligned CNT forests. The 3-dimensional carbon-Raney®Ni composite electrodes show reasonable specific capacitance of ~12 F·g-1 in electric double-layer capacitors as well as a low turn-on field (<1.0 V·µm-1) in field emitter devices. CNT-Nafion®-trifluoroacetylazobenzene coatings on glassy carbon electrodes outperform their Nafion®-trifluoroacetylazobenzene counterparts in electrochemical sensing of different amine compounds (e.g. 10 mM cadaverine, putrescine or ammonia). Cu and CuPd/buckypaper composites display catalytic activity in electrocatalytic oxidation of methanol in alkaline media. On the other hand, nanocomposites of WC and WS2 with aligned CNT forest exhibit a promising performance in hydrogen evolution reactions with an overpotential between -0.5 and -0.7 V at pH~1. In addition, these respective CNT forest aligned nanocomposites also demonstrate a novel method to obtain macroscopic 3-dimensional catalytic electrode assemblies. The results in this thesis elucidate the combination of carbon based nanostructures with organic and inorganic materials as a feasible and versatile approach to produce electrodes for several applications. The following studies of each active carbonaceous composite are expected to boost the technological innovation in relevant fields and initiate further development for commercial exploitation. / Tiivistelmä Työn tavoitteena oli demonstroida moniulotteisia hiilinanoputkirakenteita (CNT), joihin yhdistetään erilaisia aktiivisia materiaaleja sekä arvioida niiden suorituskykyä elektrodisovelluksissa, kuten kenttäemitterissä, sähköisissä kaksoiskerroskondensaattoreissa ja sähkökemiallisissa anturi- ja katalyyttikomponenteissa. Moniulotteisten CNT-nanorakenteiden konstruoiminen muiden aktiivisten materiaalien isäntämateriaaliksi toteutettiin kahdella tavalla. Ensimmäisessä toteutuksessa sovellettiin katalyyttis-kemiallista pinnoitusta, jolla kasvatettiin suoraan kolmiulotteisia hiilinanorakenteita sekä kuitumaisena hiilenä että pystysuuntaan orientoituneina hiilinanoputkimetsinä. Toinen päämenetelmä oli hiilinanoputkien immobilisointi dispersioista kaksiulotteisiksi pinnoitteiksi ja itsetukeutuviksi huokoisiksi hiilinanoputkipapereiksi. Hiiltä sisältäviä aktiivisten materiaalien nanokomposiitteja valmistettiin useilla menetelmillä, kuten (i) kasvattamalla nanoputkia ja kuitumaisia rakenteita huokoisiin Ni-katalyyttirakenteisiin, (ii) kyllästämällä hiilinanoputkia orgaanisilla reseptorimolekyyleillä tai Pd-nanopartikkeleilla, (iii) pinnoittamalla ja korvaamalla nanoputkien päällä olevaa kuparia palladiumilla kemiallisten ja galvaanisten reaktioiden avulla, (iv) hehkuttamalla hiilinanoputkien pinnalle höyrystettyä wolframia (W) muodostamaan CNT-WC-komposiitteja kiinteä–kiinteä-reaktiolla sekä (v) antamalla rikkihöyryn reagoida W-pinnoitettujen hiilinanoputkien kanssa lamellaaristen CNT-WS2-kalkogenidirakenteiden syntetisoimiseksi pystysuuntaan orientoituneisiin CNT-metsiin. Kolmiulotteisilla hiili–Raney®Ni-komposiittielektrodeilla saavutetaan kohtuullinen ominaiskapasitanssi (~12 F·g-1) sähköisissä kaksoiskerroskondensaattoreissa ja pieni kytkeytymiskenttä (<1,0 V·μm-1) kenttäemitterikomponenteissa. CNT-Nafion®-trifluoroasetyyliatsobentseeni-pinnoitteet lasimaisilla hiilielektrodeilla ovat selvästi parempia erilaisten amiiniyhdisteiden (esimerkiksi 10 mM kadaveriini, putreskiini tai ammoniakki) sähkökemiallisessa havaitsemisessa kuin vastaavat Nafion®-trifluoroasetyyliatsobentseeni-pinnoitteet. Cu- ja CuPd-hiilinanoputkipaperikomposiitit osoittavat katalyyttistä aktiivisuutta metanolin sähkökatalyyttisessä hapettumisessa emäksisessä väliaineessa. Toisaalta WC- ja WS2-yhdisteiden ja orientoituneiden CNT-metsien muodostamat nanokomposiitit osoittavat lupaavaa suorituskykyä vedynmuodostamisreaktiossa -0,5…-0,7 V ylipotentiaalilla, ja nämä myös demonstroivat uutta menetelmää makroskooppisten kolmiulotteisten katalyyttisten elektrodirakenteiden toteuttamiseksi. Väitöskirjan tulokset osoittavat, että hiilipohjaisten nanorakenteiden ja orgaanisten/epäorgaanisten materiaalien yhdistäminen on toteuttamiskelpoinen ja monipuolinen lähestymistapa elektrodien valmistamiseksi useisiin sovelluksiin. Kunkin työssä esitetyn aktiivista hiiltä sisältävän komposiitin tutkimuksen odotetaan lisäävän kyseisen alan teknisiä innovaatioita ja synnyttävän lisää kehitystyötä tutkimuksen kaupalliseksi soveltamiseksi.
125

Simulation d'un supercondensateur à l'échelle atomique

Delfour, Laure 20 June 2011 (has links)
Les supercondensateurs sont des systèmes de stockage et de conversion de l'énergie électrochimique dont les densités de puissance et d'énergie sont supérieures à celles des batteries et des condensateurs diélectriques. L’optimisation de leurs performances requiert l’utilisation de matériaux d’électrode à grande surface spécifique tels que les carbones poreux. En particulier, il est possible d’obtenir des systèmes microporeux de porosité prédéterminée par la synthèse de répliques carbonées de zéolithes. Simuler un supercondensateur à l’échelle atomique permettrait de guider le choix des matériaux le composant. Nous avons étudié un système modèle comprenant deux électrodes en réplique carbonée de zéolithe Faujasite ainsi que d’un électrolyte représenté par un système de sphères chargées. Des calculs en Liaisons Fortes de la structure électronique de la matrice carbonée fournissent la distribution de charge dans les électrodes. L’adsorption des ions dans la porosité est étudiée via des simulations Monte Carlo, dans lesquelles les interactions entre ions sont traitées par l’intermédiaire de la méthode de la sommation d’Ewald pour la partie électrostatique, et par un potentiel de Lennard-Jones pour la partie chimique. Les charges sont redistribuées de façon auto-cohérente au cours de la simulation, et la matrice poreuse est relaxée sous l’influence de l’électrolyte. Nous avons pu ainsi mettre en évidence la façon dont les différents éléments (ions, atomes de carbone), et donc la charge, se répartissent à l’interface entre électrode et électrolyte. / Electric double-layer capacitors, also known as supercapacitors, are electrochemical capacitors that have an unusually high energy density compared to that of usual high-capacity electrolytic ones. Being generally admitted that storage density is improved through the use of a nanoporous materials, a good way to optimize supercapacitors, which require carbon materials, is to synthesise carbon replica with predetermined porosity from microporous materials such as zeolites. Modeling such supercapacitors at the atomic scale should help with the choice of its components. Our model system has both electrodes in zeolite carbon replica C-FAU, and has hard charged spheres as its electrolyte. Tight-binding calculations of the electronic structure of the carbon template give the charge distribution in the electrodes, while the absorption of the ions into the pores is studied through Monte Carlo simulations, in which the interactions between the ions are treated using Ewald summations for coulombic interactions and a Lennard-Jones short-range potential for chemical interactions. Relaxation of the electrodes under the influence of the electrolyte has been tested as well. This shows how charge and matter locate themselves at the electrode/electrolyte interface.
126

Transport a ukládání náboje ve struktuře superkondenzátoru / Charge Transport and Storage in a Supercapacitor Structure

Kuparowitz, Tomáš January 2017 (has links)
Práce se zabývá studiem superkondenzátorů (SC). Výstupem je detailní studie principů přenosu náboje ve struktuře SC, ukládání energie a nový náhradní model SC, který je založen na fyzikálních zákonitostech a principech SC. Dále byl vytvořen matematický model SC, který popisuje chování náboje v jeho aktivní vrstvě. SC byly testovány metodami umělého stárnutí. Závislosti poklesu parametrů SC vlivem různých metodik stárnutí jsou v práci shrnuty.
127

Obecní restaurace / Municipal restaurant

Dokulil, Petr January 2018 (has links)
Diploma thesis on a topic ‘Municipal restaurant‘ deals with a new building proposal of a restaurant. An object is designed in the central part of a village called Štěměchy. It is a brick detached building in a slightly sloping terrain. The new building is a double-storeyed. The building has a letter ‘L‘ shape in the floor plan. The main entrance is situated from the south-east side. We can enter the restaurant from the wind lobby. The restaurant is connected with a bar and an outdoor terrace. There is a beverage store etc. next to the bar. A sanitary located background and a cleaning room are at the back side. There are accessible bowling lanes from this place. There are two entrances to the building from the north-east side. We can enter the outdoor equipment storage from the first door and the second one to the hallway which is served as for deliveries, an employee´s entrance and for taking the rubbish out from the waste repository of the kitchen. The hallway connects the restaurant to the kitchen which adheres to the rough vegetable preparation, a store with a freezer and some fridges, a dry store, a background for employees, an office, a cleaning room, an oil store, a mixed waste, a cooled waste and a utility room. There is an attic which is accessible from the wind lobby behind the main entrance. We can go to the hallway up the stairs. The hallway connects the area for exercise and an associated store of exercise aids to the roof terrace, the cleaning room and the sanitary facilities. The sanitary facilities is divided to the men´s part and women´s part. It is made by changing rooms, showers and toilets. The wall system is formed by ceramic blocks of Porotherm. There are a timber joist floor and a plank floor in the attic part. There is a system ceiling of Porotherm company where is placed a warm flat roof´s assembly with an extensive greenery . The attic part is roofed by the sloping gable double–layer roof which is made by a timber collar beam´s roof truss.
128

Mateřská škola / Kindergarten

Slezák, Václav January 2020 (has links)
The subject of this diploma thesis is the building design and project documentation of a new kindergarten in Brno. It is a new detached building structure with two floors, designed on a flat plot no. 1510/1 in cadastre unit Brno – Komín. The building is constructed of clay masonry with contact thermal insulation, supported by strip foundations. Ceiling construction is made of prestressed hollow-core slabs. This object is roofed by a single-layer and double-layered, flat roof. This kindergarten is designed for 60 children divided into three sections. Two sections are located on the 1st floor together with food preparation and technical rooms. The third section is on the 2nd floor with headquarters and a common room. This project was developed using AutoCAD software. The focus during development was on the proposed layout design in accordance with the kindergarten’s operations.
129

Aprotické elektrolyty pro superkondenzátory / Aprotic electrolytes for supercapacitors

Musílek, Václav January 2010 (has links)
This master´s thesis deals different types of the aprotic electrolytes for supercapacitors and investigates by impedance spectroscopy to conductivity and method cyclic voltametry to measure dimension potential windows. Used aprotic solvents: propylencarbonate, dimethylsulfoxide, N, N dimethylformamide, ethylencarbonate, dimethylcarbonate, diethylcarbonate and acetonitrile. In the aprotic solvents were appended salts: LiClO4, NaClO4, KClO4, LiBF4, LiPF6, TEABF4 and TMABF4. From these compounds were prepared solutions with the different molar concentrations.
130

Gelové polymerní elektrolyty pro superkondenzátory / Gel polymer electrolytes for supercapacitors

Bláha, Vladimír January 2011 (has links)
This master’s thesis deals with supercapacitors and polymer gel electrolytes. The practical part deals with the preparation of samples of polymer gel electrolyte with addition of alkali salts by measuring their electrical conductivity and evaluation potential windows.

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