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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.
1

Studium dvojhvězd s akrečními disky / A study of binary stars with accretion disks

Chadima, Pavel January 2011 (has links)
This thesis contains spectroscopic analyses of two unusual binaries with circum- stellar disks - β Lyr and ǫ Aur. Several hundred optical spectra were processed and analyzed for both binaries which led to several original findings. For β Lyr, it was a discovery of a weak shell spectrum originating in a disk pseudophotosphere and a hidden satellite spectrum, present only during eclipses, which arise from additional absorption of the primary light passing through the gaseous envelope around the secondary. For ǫ Aur, it led to the discovery of the apparent multiperiodic line vari- ability occuring during the current eclipse with a dominant and common period of 66d .21 and to an explanation of complex Hα line profiles during the eclipse which is again caused by an additional absorption of a primary light in an atmosphere of a dark disk around a secondary. Also rich series of radial velocity measurements and photometric observations were collected and used to determine a new precise orbital solution for ǫ Aur. Further, a hydrodynamical and a radiative modeling of a discontinuous mass transfer in a close binary system was carried out which resulted in a formation of an elongated disk with a slow prograde revolution, demonstrated itself by double emission Hα line profiles that exhibit V/R variations.
2

Closed To Open Sourve GIS : First Steps In Reverse Engineering ESRI's Layer Defintion File Format

Ardung, Ola January 2017 (has links)
Visualization of digital geographic data is often accomplished through custom symbology that is saved in a proprietary format called a layer file (.lyr). The sharing of free geographical information system (GIS) data can be limited as the symbology data is bound inthe .lyr file format. This makes it harder and more tedious to work with open software tools since it is not possible to convert or open the .lyr file in free and open GIS software and thus limits the distribution of free GIS data. The aim of this thesis is to increase the interoperability of .lyr data between proprietary and free and open GIS software. This was done by revers eengineering the .lyr file format to document the file structure and to distribute the knowledge and metadata gained from this project to the open source community. Reverse engineering the.lyr format provided a well needed metadata and documentation about the format which increases the interoperability and enable future work to continue to lessen the gap between open source and commercial software. This groundwork can therefore, enable a continued development of data interoperability between proprietary and free and open GIS software.

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