National Repository of Grey Literature 19 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Czech Contexts of the Corpus al-Sufi Latinus
Hadravová, Alena ; Hadrava, Petr
The contribution is based on a study of manuscripts of corpus al-Sufi Latinus carried out in connection with the preparation of an edition of the ms. Praha, The Royal Canonry of Premonstratensians at Strahov, DA II 13 (al-Sufi, Catalogus stellarum fixarum, The Catalogue of Fixed Stars).
Cristannus de Prachaticz’s Treatises on the Astrolabe
Hadrava, Petr ; Hadravová, Alena
The authors' computer methods of collation and statistical treatment of variant readings are summarized and illustrated on the example of the critical edition of the treatises on Composition and Use of the Astrolabe written by the 15th-century Czech scholar Cristannus de Prachaticz.\n
Physics of X-ray binaries
Čechura, Jan ; Hadrava, Petr (advisor) ; Heyrovský, David (referee) ; Krtička, Jiří (referee)
Title: Physics of X-ray binaries Author: Jan Čechura Department: Astronomical Institute of the Academy of Sciences of the Czech Republic Supervisor: doc. RNDr. Petr Hadrava, DrSc. Abstract: We present a novel observation interpreting method for the high-mass X-ray binaries (HMXBs) based on a combination of spectroscopic data and numerical results of a radiation hydrodynamic model of stellar wind in HMXBs. By using an indirect imaging method of Doppler tomography, we calculate synthetic tomograms of a predicted emission in Low/Hard and High/Soft X-ray states and compare them with tomograms produced using phase-resolved optical spectra of Cygnus X-1, a prototype of HMXBs. The emis- sions of HMXBs are determined by the local conditions within the circumstellar medium - namely by local density, temperature, and ionization parameter. These quantities are computed by the radiation hydrodynamic code and strongly depend on the X-ray state of such systems. By increasing intensity of an X-ray emission produced by the compact companion in the HMXB-model, we achieved a complete redistribution of the circumstel- lar medium in the vicinity of the modelled system. These changes (which simulate the transitions between two major spectral states) are also apparent in the synthetic Doppler tomograms which are in a good...
Particle motion in the vicinity of compact stellar objects
Čechura, Jan ; Šubr, Ladislav (referee) ; Hadrava, Petr (advisor)
In this thesis we discuss the properties of a radiation-driven stellar wind in an X-ray binary system. Using the parameters appropriate for the high mass Xray binary system Cygnus X-1, the effects of the compact companion on the stellar wind are examined. We have developed a full 3D hydrodynamic model of circumstellar mass based on a modified version of the Castor, Abbott & Klein line-driven mechanism. The effects of the compact companion - gravity and continuum radiation pressure - as well as the centrifugal and Coriolis force due to orbital motion are included. These forces subvert the spherical symmetry of the wind and lead to significantly different results then previous strictly radial hydrodynamic simulations.
Proposal of Motivation Program of Company
Veverka, Tomáš ; Hadrava, Petr (referee) ; Zich, Robert (advisor)
This Master Degree Project should offer the appropriate system of evaluation and motivation for the employees - as a managers' product of business department in the Olterm and TD Olomouc, a.s., so that the system given would be fair and motivating for theemployees of business.
Opticka spektroskopie Cyg X-1
Hadrava, Petr
The star HDE 226868 known as an optical counterpart of the black hole candidate Cyg X-1 has been observed in H_alpha region using spectrograph at Ondrejov 2-m telescope. The orbital parameters are determined from HeI-line by means of the author's method of Fourier disentangling. Preliminary results are also presented of disentangling the H_alpha-line into a P-Cyg profile of the (optical) primary and an emission profile of the circumstellar matter (and a telluric component).
Kinetický model kvasiperiodických oscilací plynných prstenců
Hadrava, Petr
In context of 3:2 resonant quasiperiodic oscillations, a method of "1+1/2 -dimensional" non-ideal gas dynamics is used to model axisymmetric oscillations of an orbiting ring. It is shown that the characteristic frequencies of the oscillations are influenced by the degree of freedom in the inner shear of the ring and by the rate of relaxation.

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