• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 34
  • 7
  • 2
  • 1
  • Tagged with
  • 44
  • 30
  • 15
  • 10
  • 7
  • 6
  • 6
  • 6
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 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.
11

Historická topografie města Kostelce nad Černými Lesy / The Historical topography of Kostelec nad Černými lesy town

Mrvík, Vladimír Jakub January 2012 (has links)
English abstract The aim of my thesis is to use usual methodologies and above all finding new ways of historical urban topography, applied to a representative of a small town, which since the 16th century has evolved from agrarian center seat for a wide area - Kostelec nad Černými lesy. Kostelec is one of the smaller Czech towns located in the district Prague-East and currently has about 3,500 inhabitants. In particular, there exists relatively rich and complex source material preserved from the 16th century (primary a series of cadastral and urban books and an extensive aristocratic-domain archive). 1. Topics of historic urban topography: A) Problems associated with urban planning or development of the oldest cities in the absence of the written sources 1. Evaluation of the position of town/city. 2. Before-location situation. 3. New location in town, depending on upgrade- privilege in comparison with analogous cases. 4. communication scheme over the centuries. B) Problems associated with individual objects or their architecture and typology 1. Overview of all owners and house prices in a specific year and season, depending on economical or physical condition of the building. 2. Whether the house was wooden, stone, brick, or whether it had the attic floor, the approximate number of habitable rooms and...
12

Město Opočno v topografických pramenech z 18. a 19. století / The town of Opočno in topographic sources of the 18. and 19. centuries

Tůmová, Martina January 2014 (has links)
TŮMOVÁ, M., The town of Opočno in topographic sources of the 18. and 19. centuries, diploma thesis, The Faculty of Arts of Charles University in Prague, 2014, 191 p., 11 app. The topic of the diploma thesis is to capture the town of Opočno and its landscape in selected significant topographic sources of the 18th and 19th century. The main aim is to compare relevance and value of the selected significant sources and to assemble a picture of the town's landscape in the past. An introduction integrates the topic of the diploma into various historic regionality and covers a brief history and description of a state of the town of Opočno. The thesis is divided into several chapters according to the selected sources. We paid particular attention to cadastral documentation of the first Military Survey and to Stable cadaster that includes written and cartographical materials of the town. These sources are comparable because of the diverse time interval and the different purposes of origin. In order to provide thorough understanding of the studied sources and the region, the thesis includes picture elements, supplements and samples of historic and contemporary maps. Keywords: Opočno, topography, 1st Military Survey, Stable cadaster, urban area
13

Technologie frézování tenkostěnných součástí pro letecký průmysl / On the milling technology of thin-walled parts for aerospace industry

Ohnišťová, Petra January 2016 (has links)
This thesis is focused on the analysis and on the design of the milling technology of the components for the aerospace industry which are characterised by a high aspect ratio, reduced stiffness and all covered by a high demand on the fatigue performance. This work includes the experimental verification of the proposed technology using CNC machining center, evaluation of surface structure using optical high-resolution 3D surface measurement system ALICONA, analysis of the force loading using KISTLER device, fatigue testing and fatigue fracture analysis.
14

Characterization of Arctic Environment by Means of Polarimetric Synthetic Aperture Radar (PolSAR) Data and Digital Elevation Models (DEM) / Charakterisierung der arktischen Landoberfläche mittels polarimetrischer Radardaten (PolSAR) und digitalen Höhenmodellen (DEM)

Ullmann, Tobias January 2015 (has links) (PDF)
The ecosystem of the high northern latitudes is affected by the recently changing environmental conditions. The Arctic has undergone a significant climatic change over the last decades. The land coverage is changing and a phenological response to the warming is apparent. Remotely sensed data can assist the monitoring and quantification of these changes. The remote sensing of the Arctic was predominantly carried out by the usage of optical sensors but these encounter problems in the Arctic environment, e.g. the frequent cloud cover or the solar geometry. In contrast, the imaging of Synthetic Aperture Radar is not affected by the cloud cover and the acquisition of radar imagery is independent of the solar illumination. The objective of this work was to explore how polarimetric Synthetic Aperture Radar (PolSAR) data of TerraSAR-X, TanDEM-X, Radarsat-2 and ALOS PALSAR and interferometric-derived digital elevation model data of the TanDEM-X Mission can contribute to collect meaningful information on the actual state of the Arctic Environment. The study was conducted for Canadian sites of the Mackenzie Delta Region and Banks Island and in situ reference data were available for the assessment. The up-to-date analysis of the PolSAR data made the application of the Non-Local Means filtering and of the decomposition of co-polarized data necessary. The Non-Local Means filter showed a high capability to preserve the image values, to keep the edges and to reduce the speckle. This supported not only the suitability for the interpretation but also for the classification. The classification accuracies of Non-Local Means filtered data were in average +10% higher compared to unfiltered images. The correlation of the co- and quad-polarized decomposition features was high for classes with distinct surface or double bounce scattering and a usage of the co-polarized data is beneficial for regions of natural land coverage and for low vegetation formations with little volume scattering. The evaluation further revealed that the X- and C-Band were most sensitive to the generalized land cover classes. It was found that the X-Band data were sensitive to low vegetation formations with low shrub density, the C-Band data were sensitive to the shrub density and the shrub dominated tundra. In contrast, the L-Band data were less sensitive to the land cover. Among the different dual-polarized data the HH/VV-polarized data were identified to be most meaningful for the characterization and classification, followed by the HH/HV-polarized and the VV/VH-polarized data. The quad-polarized data showed highest sensitivity to the land cover but differences to the co-polarized data were small. The accuracy assessment showed that spectral information was required for accurate land cover classification. The best results were obtained when spectral and radar information was combined. The benefit of including radar data in the classification was up to +15% accuracy and most significant for the classes wetland and sparse vegetated tundra. The best classifications were realized with quad-polarized C-Band and multispectral data and with co-polarized X-Band and multispectral data. The overall accuracy was up to 80% for unsupervised and up to 90% for supervised classifications. The results indicated that the shortwave co-polarized data show promise for the classification of tundra land cover since the polarimetric information is sensitive to low vegetation and the wetlands. Furthermore, co-polarized data provide a higher spatial resolution than the quad-polarized data. The analysis of the intermediate digital elevation model data of the TanDEM-X showed a high potential for the characterization of the surface morphology. The basic and relative topographic features were shown to be of high relevance for the quantification of the surface morphology and an area-wide application is feasible. In addition, these data were of value for the classification and delineation of landforms. Such classifications will assist the delineation of geomorphological units and have potential to identify locations of actual and future morphologic activity. / Die polaren Regionen der Erde zeigen eine hohe Sensitivität gegenüber dem aktuell stattfindenden klimatischen Wandel. Für den Raum der Arktis wurde eine signifikante Erwärmung der Landoberfläche beobachtet und zukünftige Prognosen zeigen einen positiven Trend der Temperaturentwicklung. Die Folgen für das System sind tiefgehend, zahlreich und zeigen sich bereits heute - beispielsweise in einer Zunahme der photosynthetischen Aktivität und einer Verstärkung der geomorphologischen Dynamik. Durch satellitengestützte Fernerkundungssysteme steht ein Instrumentarium bereit, welches in der Lage ist, solch großflächigen und aktuellen Änderungen der Landoberfläche nachzuzeichnen und zu quantifizieren. Insbesondere optische Systeme haben in den vergangen Jahren ihre hohe Anwendbarkeit für die kontinuierliche Beobachtung und Quantifizierung von Änderungen bewiesen, bzw. durch sie ist ein Erkennen der Änderungen erst ermöglicht worden. Der Nutzen von optischen Systemen für die Beobachtung der arktischen Landoberfläche wird dabei aber durch die häufige Beschattung durch Wolken und die Beleuchtungsgeometrie erschwert, bzw. unmöglich gemacht. Demgegenüber eröffnen bildgebende Radarsystem durch die aktive Sendung von elektromagnetischen Signalen die Möglichkeit kontinuierlich Daten über den Zustand der Oberfläche aufzuzeichnen, ohne von den atmosphärischen oder orbitalen Bedingungen abhängig zu sein. Das Ziel der vorliegenden Arbeit war es den Nutzen und Mehrwert von polarimetrischen Synthetic Aperture Radar (PolSAR) Daten der Satelliten TerraSAR-X, TanDEM-X, Radarsat-2 und ALOS PALSAR für die Charakterisierung und Klassifikation der arktischen Landoberfläche zu identifizieren. Darüber hinaus war es ein Ziel das vorläufige interferometrische digitale Höhenmodel der TanDEM-X Mission für die Charakterisierung der Landoberflächen-Morphologie zu verwenden. Die Arbeiten erfolgten hauptsächlich an ausgewählten Testgebieten im Bereich des kanadischen Mackenzie Deltas und im Norden von Banks Islanld. Für diese Regionen standen in situ erhobene Referenzdaten zur Landbedeckung zur Verfügung. Mit Blick auf den aktuellen Stand der Forschung wurden die Radardaten mit einem entwickelten Non-Local-Means Verfahren gefiltert. Die co-polarisierten Daten wurde zudem mit einer neu entwickelten zwei Komponenten Dekomposition verarbeitet. Das entwickelte Filterverfahren zeigt eine hohe Anwendbarkeit für alle Radardaten. Der Ansatz war in der Lage die Kanten und Grauwerte im Bild zu erhalten, bei einer gleichzeitigen Reduktion der Varianz und des Speckle-Effekts. Dies verbesserte nicht nur die Bildinterpretation, sondern auch die Bildklassifikation und eine Erhöhung der Klassifikationsgüte von ca. +10% konnte durch die Filterung erreicht werden. Die Merkmale der Dekomposition von co-polarisierten Daten zeigten eine hohe Korrelation zu den entsprechenden Merkmalen der Dekomposition von voll-polarisierten Daten. Die Korrelation war besonders hoch für Landbedeckungstypen, welche eine double oder single bounce Rückstreuung hervorrufen. Eine Anwendung von co-polarisierten Daten ist somit besonders sinnvoll und aussagekräftig für Landbedeckungstypen, welche nur einen geringen Teil an Volumenstreuung bedingen. Die vergleichende Auswertung der PolSAR Daten zeigte, dass sowohl X- als auch C-Band Daten besonders sensitiv für die untersuchten Landbedeckungsklassen waren. Die X-Band Daten zeigten die höchste Sensitivität für niedrige Tundrengesellschaften. Die C-Band Daten zeigten eine höhere Sensitivität für mittelhohe Tundrengesellschaften und Gebüsch (shrub). Die L-Band Daten wiesen im Vergleich dazu die geringste Sensitivität für die Oberflächenbedeckung auf. Ein Vergleich von verschiedenen dual-polarisierten Daten zeigte, dass die Kanalkombination HH/VV die beste Differenzierung der Landbedeckungsklassen lieferte. Weniger deutlich war die Differenzierung mit den Kombinationen HH/HV und VV/VH. Insgesamt am besten waren jedoch die voll-polarisierten Daten geeignet, auch wenn die Verbesserung im Vergleich zu den co-polarisierten Daten nur gering war. Die Analyse der Klassifikationsgenauigkeiten bestätigte dieses Bild, machte jedoch deutlich, dass zu einer genauen Landbedeckungsklassifikation die Einbeziehung von multispektraler Information notwendig ist. Eine Nutzung von voll-polarisierten C-Band und multispektralen Daten erbrachte so eine mittlere Güte von ca. 80% für unüberwachte und von ca. 90% für überwachte Klassifikationsverfahren. Ähnlich hohe Werte wurden für die Kombination von co-polarisierten X-Band und multispektralen Daten erreicht. Im Vergleich zu Klassifikation die nur auf Grundlage von multispektralen Daten durchgeführt wurden, erbrachte die Einbeziehung der polarisierten Radardaten eine zusätzliche durchschnittliche Klassifikationsgüte von ca. +15%. Der Zugewinn und die Möglichkeit zur Differenzierung war vor allem für die Bedeckungstypen der Feuchtgebiete (wetlands) und der niedrigen Tundrengesellschaften festzustellen. Die Analyse der digitalen Höhenmodelle zeigte ein hohes Potential der TanDEM-X Daten für die Charakterisierung der topographischen Gegebenheiten. Die aus den Daten abgeleiteten absoluten und relativen topographischen Merkmale waren für eine morphometrische Quantifizierung der Landoberflächen-Morphologie geeignet. Zudem konnten diese Merkmale auch für eine initiale Klassifikation der Landformen genutzt werden. Die Daten zeigten somit ein hohes Potential für die Unterstützung der geomorphologischen Kartierung und für die Identifizierung der aktuellen und zukünftigen Dynamik der Landoberfläche.
15

Pokročilé metody vyhodnocování topografie povrchu součásti / Advanced methods of surface topography evaluation

Šindelka, Marek January 2019 (has links)
This thesis focuses on a measuring and topography of a components´ surface evaluation and it contains the overview of basic methods which includes the description of contact and non-contact measuring devices. Furthermore, the thesis also describes ways of surface texture evaluation through profiled and areal method, including an outline of ČSN ISO parameters. The practical part of the thesis focuses on the evaluation of metric threads´ M10 surface, crafted by diverse cutting and forming threads. The surface was scanned with the optical device called Alicona IFM G5 and it was evaluated through the profiled and areal method. The 2D and 3D parameters were acquired and then compared during the measuring.
16

Pokročilé metody vyhodnocování topografie povrchu / Advanced methods of surface topography evaluation

Hroděj, Daniel January 2020 (has links)
This paper deals with the analysis of data obtained from the surface of aluminum alloy 7475-T7351 after face milling with a tool inclination of 1°. The theoretical part explains the basic principles of measuring the topography of the surface and instruments that are able to provide relevant data directly from the scanned part. The following part contains the methods of evaluating the information, especially using various types of parameters acquired from ČSN EN ISO standards. The practical part focuses on the data obtained from the sample surface using the Alicona IF-G5. This information determines the character of the surface texture with the tool inclination and the difference between the profile and surface parameters. There is also described surface texture in the tool path and on the edge of the tool path. In the final economic evaluation, the connection between the feed per tooth and the machining price is found.
17

Lokální charakterizace elektronických součástek / Local characterization of electronic devices

Müller, Pavel January 2010 (has links)
The development of micro and nanoelectronics and nanophotonics needs novel characterization techniques to ensure higher quality of designed devices. The thesis describes a use of Scanning Near-field Optical Microscopy (SNOM) in dimensional control and in local investigation of diverse physical parameters. As example of its potential, the correlation between object topography and reflection measurement of capacitors is shown.
18

Vliv cílené modifikace topografie na únavové poškozování třecích povrchů / Effect of surface texturing on rolling contact fatigue of rubbing surfaces

Popelka, Jakub January 2008 (has links)
Diploma thesis describes influence of directed modificated topography of frictional surfaces on fatigue wear non-conformal incurvate solids. It was created 3D parametric model of experimental test rig in modelling environment Autodesk Inventor. With the help of model was designed and carried reconstruction of experimental test rig so to possible obtain repeatable results under the sliding conditions of frictional surfaces. It enabled show influence of surface iregularities (dents) frictional surfaces on contact fatigue service life in conditions mixed lubrication regime and different values of slide to roll ratio.
19

Vliv cílené modifikace topografie na elastohydrodynamické mazací filmy / Effect of surface texturing on elastohydrodynamic films

Puchner, Jiří January 2008 (has links)
Diploma thesis describes analysis of influence of surface texturing on non-conformal rubbing surfaces. High speed camera was used to observe the effect of micro-dents of various depths on film thickness under pure rolling and rolling/sliding conditions. It can be concluded from the obtained results that micro-texture of suitable sizes can results in film thickness increase without lubrication film breakdown.
20

Konstrukce zařízení pro modifikaci topografie třecích povrchů / Design of Equipment for Surface Topography Modification

Kománek, Jiří January 2013 (has links)
This master thesis is focused on design and construction of laboratory shot peening machine. This machine is determined for modification of the topography of the friction surfaces specimens. Two types of specimens are used. The first specimen is sphere with diameter 20-40 mm. The second specimen is cylinder with 9.6 mm diameter. In this thesis the setting parameters of shot peening for creation of surface with the micro-texture was described. Influence of the micro-texture to the coefficient of friction was investigated under mixed lubrication and slip condition.

Page generated in 0.0338 seconds