National Repository of Grey Literature 8 records found  Search took 0.00 seconds. 
Properties of faint meteors studied by video observations
Vojáček, Vlastimil ; Borovička, Jiří (advisor) ; Campbell-Brown, Margaret (referee) ; Tóth, Juraj (referee)
Parallel double-station video observations paired with spectroscopic video observations are a good way to study millimetre-sized meteoroids. Almost two decades of video observations of meteors at the Ondřejov observatory give us broad database to study large quantities of meteoroids and their properties. In this work we combined spectral video observations and results of the modelling of the fragmentation of meteoroids. Along with complex infor- mation about meteoroid's trajectories and orbits, this can give us better understanding about origin, internal structure etc. of these millimetre-sized interplanetary bodies. Meteoroids that contained small grains tend to release the sodium early. Since there is a smaller amount of sodium for Na depleted meteoroids, the sodium was released earlier than it was released for meteoroids with same grain sizes and without the sodium depletion. Overall, meteoroids with sodium depletion showed different composition: they were composed of stronger material without very small grains and they did not showed very bright wakes. Two iron meteoroids on Halley type orbits were observed. They are probably remnants of complicated early years of our solar system. The dis- tribution of grain sizes of Jupiter-family members was in a good agreements with results from the COSIMA...
Dynamics of small bodies in the Solar System: from dust particles to asteroid
Pokorný, Petr ; Vokrouhlický, David (advisor) ; Borovička, Jiří (referee) ; Wiegert, Paul (referee)
In this thesis, we study two different topics: collisional probability between two bodies and dynamics of the sporadic meteoroids in the Solar System. Determination of the collision probabilities in the Solar System is one of the important problems in mod- ern celestial mechanics. Here, we generalize classical theories of the collisions between two bodies by Öpik, Wetherill or Greenberg by including the Kozai-Lidov oscillations, a mechanism that significantly change orbital eccentricity and inclination in the Solar System. Sporadic meteors have been studied for many decades providing a wealthy re- source of data. Here, we build dynamical steady-state models for all known populations observed in the sporadic meteoroid complex based on the latest and most precise data provided by Canadian Meteor Orbit Radar (CMOR). Our models using the latest theo- ries for cometary populations in the Solar System accurately describe observed sporadic background population. Our results are in agreement with observations provided by space probes IRAS and LDEF.
Forbidden Oxygen line emission from the traces of meteors
Habuda, Pavol ; Borovička, Jiří (advisor) ; Šolc, Martin (referee)
The aim of this diploma thesis was to study forbidden green oxygen line emission. It was found out that green line emit mainly in heights 100-110 kilometers, exceptionally below 90 kilometers. Time evolution of green line intensity with respect of heights was investigated in detail. There was suggested theoretical dependency and agreement with observed data was fulfilled. Dependency of integral intensity was investigated as well. Mechanisms of excitation and quenching of green line in emission was proposed in previous studies in 70. of previous century. This work discuss with its results. Efficiency of transformation of kinetic energy of meteoroid to forbidden green line's emission was discussed. The concentrations of atomic oxygen was estimated by several way in heights of green line emission.
Time management and techniques of its use in construction company
Smejkal, Marek ; Borovička, Jiří (referee) ; Linkeschová, Dana (advisor)
The thesis deals and discusses the awareness and application of Time Management and its techniques used in the construction and building companies. The theoretical part is based on the literature which presents and explains all the concepts of time management techniques, its history and problems with planning time in construction field. The practical part of thesis is based on the data carried out from the questionnaire and controlled interviews with practitioners and it was evaluated on the basis of predetermined hypotheses.
Dynamics and fragmentations of meteoroids during their flight in the atmosphere
Kalenda, Pavel ; Borovička, Jiří ; Spurný, Pavel
The dynamic fragmentation of meteoroids during their flight in the atmosphere is described. The examples of very weak meteoroids, which easy fragments, up to strong meteoroids, which produce the explosive fragmentation, are described.

See also: similar author names
2 Borovička, Jan
1 Borovička, Jaroslav
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