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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.
431

Teplovzdušný vytápěcí a větrací systém pro nízkoenergetický rodinný dům / Warm-air heating and ventilating system for low-energy family house

Musil, Zdeněk January 2012 (has links)
The diploma thesis deals with warm-air heating and ventilation system of energyefficient family house. The part of thesis is theoretical introduction to low-energy and passive houses, ventilation and heating. The proposal itself is based on the applicable standards and includes all progressive steps, including the calculation of the thermal performance and sizing individual parts of the system. The drawing project documentation is listed in appendixes.
432

Polyfunkční dům / Multifunctional house

Kmenta, Tomáš January 2016 (has links)
Developing  a part of project documentation for a multifunctional house is the main subject of my thesis.This particular object is planned for a constructional lot in a district of Hodonín. Building has  four levels,  is separately standing, made of brick and does not have any cellar.  First floor is intended for  business and service use. Second, third and fourth floor are designed for living. There are one-room, two-room and four-room flats. Multifunctional house is made of  calcium silicate blocks and will be covered with flat roof.
433

Studium užitných vlastností tepelně-reflexních izolací pro stavebnictví / Study utility properties of heat-reflective insulation for the buildings

Rauchfussová, Karolína January 2017 (has links)
Presented work deals with the study progressive heat-reflecting foil thermal insulating materials and defines their thermal insulation properties. The work describes a transport mechanism of thermal energy in the structure of heat-reflecting materials, their physical properties, especially heat resistance, compared to the conventional thermal insulating materials available on Czech market. The main applications ways and installation methods of these materials (especially in low-energy and passive buildings) are also shown. The practical part is focused on asembling the measuring device HOT BOX in accordance with the valid standards, to determine the heat resistance of heat-reflecting materials. In next step the measurement of reflection of aluminum foils (an integral part of the structural arrangement heat-reflecting foil insulations) was performed.
434

Low-energy Electron Induced Chemistry in Supported Molecular Films / Chimie induite par électrons lents (0-20 eV) au sein de films moléculaires supportés

Sala, Leo Albert 27 November 2018 (has links)
Lorsque la matière condensée est soumise à des rayonnements de haute énergie, des électrons secondaires de basse énergie (0-20 eV) sont produits en grande quantité. Ces électrons participent à part entière aux dommages induits dans la matière, incluant les processus d’érosion et de modifications chimiques. Les fragments produits au sein du milieu réagissent et de nouvelles espèces sont formées. Plusieurs domaines d’application sont concernés par ces processus, et plus particulièrement le design de dispositifs par lithographie ou par dépôts assistés par faisceaux focalisés et l’astrochimie. Les enjeux concernent l’identification des mécanismes induits par les électrons lents, le contrôle des fragments réactifs et espèces stables formés, ainsi que la détermination de grandeurs quantitatives permettant d’apprécier l’efficacité des processus impliqués. L’approche développée dans ce travail de thèse consiste à irradier des surfaces et interfaces directement avec des faisceaux d’électrons de basse énergie afin d’étudier les processus induits. Les réponses de films moléculaires supportés modèles (d’épaisseur variable) sont étudiées en fonction de l’énergie incidente des électrons et des doses délivrées. Dans les cas favorables, des méthodologies ont pu être proposées pour accéder à l’estimation de sections efficaces effectives. Pour ce faire, trois techniques expérimentales sont combinées. Les films déposés et les résidus formés sont analysés par spectroscopie de perte d'énergie d’électrons à haute résolution (HREELS) et désorption programmée en température (TPD). Les fragments neutres (et non pas ioniques comme le plus souvent) désorbant sous irradiation sont analysés en masse afin de mener une étude de désorption stimulée par impact d’électrons (ESD).Dans le contexte de la fonctionnalisation de surface, le greffage de centres carbonés hybridés sp2 sur un substrat de diamant poly-cristallin hydrogéné a été réalisé par irradiation électronique d’une couche mince de benzylamine. A 11 eV, le mécanisme dominant implique la dissociation en neutres du précurseur. La section efficace effective de greffage a pu être déterminée par HREELS suite à une unique irradiation, en tirant avantage du profil du faisceau d’irradiation. Dans le contexte de l’astrochimie, la réponse à l’irradiation par électrons lents de glaces d’ammoniac amorphes et cristallisées a été étudiée. La désorption de molécules d’ammoniac a été observée. Elle peut résulter de l’érosion directe du film et de mécanismes de désorption induite par excitation électronique (DIET). Différents processus de fragmentation/recombinaison ont été mis en évidence via la désorption des espèces neutres NHx (x = 1,2), H2 et N2. Une chimie particulièrement riche est induite par irradiation électronique à 13 eV. L’analyse temporelle des rendements ESD a permis la détermination de la section efficace de la désorption de NH3, et l’observation de la formation retardée de N2 et H2. L’analyse TPD des résidus a démontré la synthèse de diazène (N2H2) et d’hydrazine (N2H4) dans le film. Ces résultats peuvent aider à l’élucidation des écarts observés dans les abondances de NH3 et N2 dans les régions denses de l'espace. Enfin, les premiers travaux réalisés pour fonctionnaliser un substrat de façon résolue à l’échelle micrométrique sous irradiation d’électrons lents sont également présentés. La faisabilité de la procédure utilisant un microscope électronique à basse énergie (LEEM) a été démontré sur une monocouche de terphenylthiol (TPT). Des motifs de 5 μm de travaux de sortie différents ont été imprimés en travaillant à des énergies de 10-50 eV. Ensuite la réponse de films modèles de résines lithographiques (PMMA, polyméthacrylate de méthyle) à des irradiations électroniques a été étudiée, afin d’identifier les énergies favorables en vue d’une modification de surface résolue spatialement. / High-energy irradiation of condensed matter leads to the production of copious amounts of low-energy (0-20 eV) secondary electrons. These electrons are known to trigger various dissociative processes leading to observed damages including erosion and chemical modifications. The resulting reactive species within the condensed media can also lead to the synthesis of new molecules. This has implications in several applications most especially in the design of lithographic methods, focused beam-assisted deposition, as well as in astrochemistry. In all these applications, it is important to identify the processes induced by low-energy electrons, study the reactive fragments and stable molecules produced to determine possibilities of controlling them, and generate quantitative data to gauge the efficiencies of these processes. The approach developed for this PhD work consists of directly irradiating surfaces and interfaces using low-energy electrons and studying the processes that arise. The responses of different model molecular films (of varying thickness) were studied as a function of incident electron energy and dose. In favorable cases, methodologies proposed herein can be used to estimate effective cross sections of observed processes. Three complementary surface-sensitive techniques were utilized for this purpose. To characterize the deposited films and formed residues, the High Resolution Electron-Energy Loss Spectroscopy (HREELS) and Temperature Programmed Desorption (TPD) were used. Neutral fragments (as opposed to their often-detected ionic counterparts) desorbing under electron irradiation were monitored using a mass spectrometer in a technique called Electron Stimulated Desorption (ESD).Within the context of surface functionalization, the grafting of sp2-hybridized carbon centers on a polycrystalline hydrogenated diamond substrate was realized through electron irradiation of a thin layer of benzylamine precursor deposited on its surface. At 11 eV, the dominant mechanism is proposed to be neutral dissociation of the precursor molecules. The effective cross section of the grafting process was estimated in only a single measurement from the HREELS map of the sample surface, taking advantage of the electron beam profile. Within the context of astrochemistry, on the other hand, the responses of crystalline and amorphous NH3 ices were studied under electron impact. The desorption of intact NH3 was observed which resulted in the direct erosion of the film proceeding through a mechanism consistent with desorption induced by electronic transitions (DIET). Different fragmentation and recombination processes were also observed as evidenced by detected neutral species like NHx (x=1,2), N2, and H2. Aside from desorption, a wealth of chemical processes was also observed at 13 eV. Temporal ESD at this energy allowed for the estimation of the effective cross section of NH3 desorption and observing the delayed desorption of N2 and H2. TPD analysis of the residues also provided evidence of N2H2 and N2H4 synthesis in the film. These results can help explain the observed discrepancies in abundances of NH3 and N2 in dense regions in space. Lastly, this PhD work will present prospects for these electron-induced processes to be constrained spatially in microscopic dimensions for lithographic applications. The feasibility of the procedure utilizing Low-Energy Electron Microscope (LEEM) was demonstrated on a terphenylthiol self-assembled monolayer (TPT SAM) specimen. Spots of 5 μm in diameter with different work functions were imprinted on the surface using energies from 10-50 eV. Electron-induced reactions in thin-film resists (PMMA, poly(methyl methacrylate)) were also studied at low-energy identifying opportunities for energy- and spatially-resolved surface modification.
435

Growth Monitoring of Ultrathin Copper and Copper Oxide Films Deposited by Atomic Layer Deposition

Dhakal, Dileep 16 December 2016 (has links)
Atomic layer deposition (ALD) of copper films is getting enormous interest. Ultrathin Cu films are applied as the seed layer for electrochemical deposition (ECD) of copper in interconnect circuits and as the non-magnetic material for the realization of giant magnetoresistance (GMR) sensors. Particularly, Co/Cu multi-layered structures require sub 4.0 nm copper film thickness for obtaining strong GMR effects. The physical vapor deposition process for the deposition of the copper seed layers are prone to non-conformal coating and poor step coverage on side-walls and bottoms of trenches and vias, and presence of overhanging structures. This may cause failure of interconnections due to formation of voids after copper ECD. ALD is the most suitable technology for the deposition of conformal seed layers for the subsequent ECD in very high aspect ratio structures, also for the technology nodes below 20 nm. Surface chemistry during the ALD of oxides is quite well studied. However, surface chemistry during the ALD of pure metal is rather immature. This knowledge is necessary to optimize the process parameters, synthesize better precursors systems, and enhance the knowledge of existing metal ALD processes. The major goal of this work is to understand the surface chemistry of the used precursor and study the growth of ultrathin copper films using in-situ X-ray photoelectron spectroscopy (XPS). Copper films are deposited by ALD using the precursor mixture consisting of 99 mol% [(nBu3P)2Cu(acac)], as copper precursor and 1 mol% of Ru(η5 C7H11)(η5 C5H4SiMe3), as ruthenium precursor. The purpose in having catalytic amount of ruthenium precursor is to obtain the Ru doped Cu2O layers for subsequent reduction with formic acid at temperatures below 150 °C on arbitrary substrates. Two different approaches for the growth of ultrathin copper films have been studied in this dissertation. In the first approach, direct thermal ALD of copper has been studied by using H2 as co-reactant on Co as catalytic substrate. In the second approach, Ru-doped Cu2O is deposited by ALD using wet-O2 as co-reactant on SiO2 as non-catalytic substrate. The Ru-doped Cu2O is successfully reduced by using either formic acid or carbon-monoxide on SiO2. / Atomlagenabscheidung (ALD) von Kupfer steht im Fokus der ALD Gemeinschaft. Ultradünne Kupferschichten können als Keimschicht für die elektrochemische Abscheidung (ECD) von Kupfer in der Verbindungstechnologie eingesetzt werden. Sie können ebenfalls für Sensoren, welche auf den Effekt des Riesenmagnetowiderstandes (GMR) basieren, als nicht-ferromagnetische Zwischenschicht verwendet werden. Insbesondere Multischichtstrukturen aus ferromagnetische Kobalt und Kupfer erfordern Schichtdicken von weniger als 4,0 nm, um einen starken GMR-Effekt zu gewährleisten. Das derzeit verwendete physikalische Dampfabscheidungsverfahren für ultradünne Kupferschichten, ist besonders anfällig für eine nicht-konforme Abscheidung an den Seitenwänden und Böden von Strukturen mit hohem Aspektverhältnis. Des Weiteren kann es zur Bildung von Löchern und überhängenden Strukturen kommen, welche bei der anschließenden Kupfer ECD zu Kontaktlücken (Voids) führen können. Für die Abscheidung einer Kupfer-Keimschicht ist die ALD besonders gut geeignet, da sie es ermöglicht, ultradünne konforme Schichten auf strukturierten Oberflächen mit hohem Aspektverhältnis abzuscheiden. Dies macht sie zu einer der Schlüsseltechnologien für Struckturgrößen unter 20 nm. Im Gegensatz zur Oberflächenchemie rein metallischer ALD sind die Oberflächenreaktionen für oxidische ALD Schichten sehr gut untersucht. Die Kenntnis der Oberflächenchemie während eines ALD Prozesses ist essenziel für die Bestimmung von wichtigen Prozessparametern als auch für die Verbesserung der Präkursorsynthese ansich. Diese Arbeit beschäftigt sich mit der Untersuchung der Oberflächenchemie und Charakterisierung des Wachstums von ultradünnen Metall-Cu-Schichten mittels In-situ XPS, welche eines indirekten (Oxid) bzw. direkten Metall-ALD Prozesses abgeschieden werden, wobei die Kupfer-Oxidschichten im Anschluss einem Reduktionsprozess unterworfen werden. Hierfür wird eine Präkursormischung bestehend aus 99 mol% [(nBu3P)2Cu(acac)] und 1 mol% [Ru(η5 C7H11)(η5-C5H4SiMe3)] verwendet. Die katalytische Menge an Ru, welche in der entstehenden Cu2O Schicht verbleibt, erhöht den Effekt der Reduktion der Cu2O Schicht auf beliebigen Substraten mit Ameinsäure bei Wafertemperaturen unter 150 °C. In einem ersten Schritt wird ein direkter thermisches Kupfer ALD-Prozess, unter Verwendung von molekularem Wasserstoff als Coreaktant, auf einem Kobalt-Substrat untersucht. In einem zweiten Schritt wird ein indirekter thermischer Cu2O-ALD-Prozess, unter gleichzeitiger Verwendung von Sauerstoff und Wasserdampf als Coreaktant, mit anschließender Reduktion durch Ameinsäure oder Kohlenstoffmonoxid zu Kupfer auf den gleichen Substraten betrachtet. Die vorliegende Arbeit beschreibt das Wachstum von ultradünnen und kontinuierlichen Kupfer-Schichten mittels thermischer ALD auf inerten- SiO2 und reaktiven Kobalt-Substraten.
436

Real-world Exploitation and Vulnerability Mitigation of Google/Apple Exposure Notification Contact Tracing

Ellis, Christopher Jordan January 2021 (has links)
No description available.
437

Structure and morphology of ultrathin iron and iron oxide films on Ag(001)

Bruns, Daniel 21 November 2012 (has links)
This work investigates the initial growth of iron and iron oxides on Ag(001). Surface structure and morphology of both post deposition annealed Fe films (in UHV and O2 atmosphere) as well as reactive grown iron oxide films will be analyzed in detail by low energy electron diffraction (LEED) and scanning tunneling microscopy (STM). The stoichiometry at the surface of the iron oxide films will be determined by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The main focus of this work is to shed light on the question whether the growth of iron oxide films on Ag(001) is accompanied by the formation of strain reducing dislocation networks, or superstructures as found for other metal substrates in former studies. Here, we will distinguish between Fe films which were post deposition annealed in a thin O2 atmosphere and reactively grown iron oxide films.
438

Praseodymia on non-passivated and passivated Si(111) surfaces

Gevers, Sebastian 04 July 2011 (has links)
In the presented thesis thin praseodymia films on non-passivated and passivated Si(111) substrates were investigated. The first part deals with PDA of praseodymia films with fluorite structure under UHV conditions in the temperature region from RT to 600°C. Here, a sophisticated model of the annealing process of praseodymia films is established. This is done by detailed analysis of XRD measurements using the kinematic diffraction theory in combination with the analysis of GIXRD, XRR and SPA-LEED measurements. It is shown that the untreated films, which are oxidized in 1 atm oxygen to obtain fluorite structure, do not exhibit pure PrO2 stoichiometry as it was assumed before. Instead, they decompose into two laterally coexisting species exhibiting a PrO2 and a Pr6O11. oxide phase, respectively. These species are laterally pinned to the lattice parameter of bulk Pr6O11. Homogeneous oxide films with Pr6O11 phase can be observed after annealing at 100°C and 150°C. Here, lateral strain caused by the pinning of the species is minimized and an increase of the crystallite sizes is determined. If higher annealing temperatures are applied, the film decomposes again into two coexisting species. Finally, after annealing at 300°C, a mixed crystalline film with both Pr2O3 and Pr2O3+Delta oxide phases is formed, where Delta denotes a considerable excess of oxygen within the sesquioxide phase. Again the lateral strain increases due to the tendency of praseodymia phases to increase their lattice parameters during oxygen loss combined with the lateral pinning. This is accompanied by a decrease of crystallite sizes, which are afterwards comparable to those of the untreated films. Further annealing at temperatures above 300°C does not significantly change the structure of the oxide film. However, the increase of the amorphous Pr-silicate interface between Si substrate and oxide at the expense of the crystalline oxide can be observed after annealing at higher temperatures. Furthermore, an increased mosaic spread of the crystallites occurs, which reduces the lateral strain caused by the oxygen loss. Nevertheless, the crystalline structure is stable against further annealing up to temperatures of 600°C. Transportation of the sample under ambient conditions after annealing at 200°C and 300°C leads to the formation of an additional crystalline structure at the surface which cannot be allocated to any praseodymia phase and may be explained by the contamination of the topmost crystalline layers with Pr-hydroxides. The results obtained from praseodymia films annealed in 1 atm nitrogen show that these films are good candidates to form homogeneous oxide films with pure cub-Pr2O3 structure by subsequent annealing in UHV. Here, a single oxide species is already observed after annealing at 300°C by SPA-LEED measurements which is in contrast to praseodymia films with fluorite structure where higher annealing temperatures (600°C) are necessary. In this case, negative effects like interface growth or increased defect density (mosaics, grain boundaries) can be minimized. Investigations on oxygen plasma-treated praseodymia films to obtain pure PrO2 stoichiometry are presented in the second part. Oxygen plasma-treated samples are compared with samples oxidized in 1 atm oxygen regarding the structure of the crystalline film. For this purpose, XRR and XRD measurements are performed to get structural information of the oxide film, which can be used to identify the corresponding oxide phases. Here, significantly smaller lattice constants of the crystalline oxide species can be observed after plasma treatment, which points to the incorporation of additional oxygen atoms. This verifies former studies, where a higher oxidation state of the oxide film was found by XPS measurements and it shows that plasma-treated films exhibit a higher oxidation state than films oxidized in 1 atm oxygen due to the availability of reactive atomic oxygen in the plasma. Furthermore, the Pr-silicate interface between crystalline film and Si substrate is not increased during plasma treatment. In the last part of the presented thesis, first results from the epitaxy of praseodymia films on Cl-passivated Si substrates are shown. The aim is to suppress the Pr-silicate formation during the growth process. Thus, praseodymia films are grown on passivated and non-passivated substrates to compare the crystallinity of both samples using XSW and LEED measurements. The structure of the oxide films on Cl-passivated Si is determined afterwards by XRR. It is shown that crystalline films with cub-Pr2O3 structure and several nanometer thickness can be successfully grown on Cl-passivated substrates. Here, the Pr-silicate interface layer are restricted to a single mono-layer. In contrast, the films grown on non-passivated substrates are completely amorphous containing Pr-silicates and Pr-silicides.
439

Optimalizace nákladů životního cyklu rodinných domů / Optimization of life cycle costs of family houses

Servusová, Michaela January 2022 (has links)
The theoretical part deals at the beginning with wooden buildings and suitable materials. Then information about low energy houses, passive houses and requirements for new buildings is introduced. The theoretical part of the work also summarizes the selection of the technological solution. Important part is about individual life cycle stages of the building, wear and tear of the buildings and whole life costs of the building that the investor is interested in. Practical part of the thesis consists of a case study of the wooden family house where the whole life costs of the building life cycle are solved.
440

Vliv architektonického konceptu na potřebu tepla na vytápění energeticky úsporných budov pro bydlení. / Impact of the architectural concept on the energy consumption of heating of the energy-saving residential buildings

Křeček, David January 2012 (has links)
Human efforts to increase their comfort rise in density of population in congested city areas, rapid growth of traffic and electric smog created due to constantly transforming communication technologies all resulted in an increase of stress in the immediate human environment. All of this, along with frequent reports about changes in global climate, gradually contributes to an alteration of thinking of the whole society, which is forced to face the consequences of economic damages caused by climatic changes. If we want to tenably assert adequate economic and social living conditions, we have to approach the natural environment in a more profound way. In accordance with the trend of substantional development for the purpose of enhancement of the quality of the living environment in the field of building industry, it is logical to concentrate on buildings, which are conceptually focused on saving of the energy. That is on energy-efficient houses. Pathway to sustainable building is not based on discovering one or several multipurpose technological solutions, but on usage of new designing principles, new materials and methods of processing them as well as new techniques of construction. For an effective creation of a building concept it is essential to have that kind of device which quickly responds to changes performed on a design, enables an easier work on variants and produces the most accurate results. Consistent application of energy optimizing methods is necessary particularly for designs of energy saving houses. Beginning efficient building design is the most “abstract factor of concept linked with very uncertain inputs,” because a lot of parameters in that moment is still unknown. Many mutually connected factors are invoked during designing passive house e.g. trajectory of the sun and the shielding effect of the surroundings, the aspect of sunlight and interior lighting, power quality construction, etc. Currently, the architect has no choice, he can use only well-known precepts, such as large windows are facing the South not the North. Unfortunately this "empirical formula" for the design of a real passive house is not enough. And yet the first draft of the house is most affected by not only its shape, form, but user´s comfortable, cost, feasibility and future energy behavior of buildings and related operating costs of the house too. It is obvious that this stage should not be underestimated, because “minor variation of the initial inputs greatly influence the outcomes.” With this reasoning, the work focuses on early stage design decision, i.e. the architectural concept of a passive house (an idea, vision). Therefore the aim of this work is to simplify the issue into understandable form, i.e. the creation of relatively simple and illustrative sketches, which generalize the issue satisfactorily, show the individual parameters (glazing, shading, shape, size, etc.) and change need of heat for heating passive house. The results of the work will be useful when the architect picks up the pencil and starts to think about his future house. At this point, he will have on hand sketches, which give him an idea and streamline his further design. Therefore the main goal is to create new outcomes and identify energy behaviour of buildings with a computational tool. This research works with virtual idealized mathematical model in the software PHPP 2007 CZ and uses "phenomenon" of parametric equations and sensitivity analysis.

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