452 research outputs found
First photometric study of the eclipsing binary PS Persei
The CCD photometric observations of the eclipsing binary PS Persei (PS Per)
were obtained on two consecutive days in 2009. The 2003 version Wilson-Devinney
code was used to analyze the first complete light curves in and bands.
It is found that PS Per is a short-period Algol-type binary with the less
massive component accurately filling its inner critical Roche lobe. The mass
ratio of and the orbital inclination of are
obtained. On the other hand, based on all available times of primary light
minimum including two new ones, the orbital period has been improved.Comment: 7 pages, 4 figure
Ejectors and it's utilization in industry
Tato práce má za cíl seznámit čtenáře s ejektorovými čerpadly. Popisuje jejich princip činnosti, výhody a nevýhody a problematiku jejich použití v různých aplikacích. Hlavní nevýhodou ejektorů je jejich nízká účinnost, a tak je jejich využití možné jen v natolik specifických aplikacích, ve kterých není účinnost rozhodujícím faktorem. Proto jsou dále uvedeny příklady použití různých typů ejektorů v průmyslových procesech. Na těchto příkladech jsou v neposlední řadě demonstrovány všechny obtíže a důvody, proč je pro danou aplikaci výhodnější použít právě ejektor, a nikoli jiný typ čerpadla. Tato práce se dále zabývá návrhovými metodami ejektorů a na ukázkovém příkladě porovnává vhodnost jejich použití. Ukazuje se, že ne všechny metody jsou pro návrhy ejektorů vhodné, neboť velmi záleží na předpokládaném tvaru řešeného ejektoru. Na závěr je porovnána i energetická náročnost ejektoru oproti běžným odstředivým čerpadlům a prokázána energetická nevýhodnost ejektorů.This work aims at introducing ejector pumps. It describes the working principle, advantages and disadvantages and restrictions of their usage in various applications. Main disadvantage of ejectors is the low efficiency which limits the usage only in specific applications where it is not considered to be a crucial factor. Therefore, examples of usage of various ejectors in industrial processes are listed further. Last but not least, in these examples are also demonstrated difficulties and reasons why it is favourable to use an ejector rather than other types of pumps. Further off, this work deals with design methods of ejectors and compares their suitability. It appears that not all the methods are suitable for ejector design, because it depends greatly on presumed shape of a certain ejector. In the end, there is compared energy intensity of an ejectors and common centrifugal pumps and confirms energy disadvantage of ejectors.
Hi-fi phenomenological description of eclipsing binary light variations as the basis for their period analysis
In-depth analysis of eclipsing binary (EB) observational data collected for
several decades can inform us about a lot of astrophysically interesting
processes taking place in the systems. We have developed a wide-ranging method
for the phenomenological modelling of eclipsing binary phase curves that
enables us to combine even very disparate sources of phase information. This
approach is appropriate for the processing of both standard photometric series
of eclipses and data from photometric surveys of all kind. We conclude that
mid-eclipse times, determined using the latest version of our 'hi-fi'
phenomenological light curve models, as well as their accuracy, are nearly the
same as the values obtained using much more complex standard physical EB
models.Comment: 4 pages, 3 figures, EAS - Proceedings of the conference: Setting a
new standard in the analysis of binary stars, 16 to 19 September 2013,
Leuven, Belgiu
Chronic obstructive pulmonary disease in Poland — a need for population-based epidemiological studies
A recent monograph “Lung Diseases” issued by the National Medical Publisher (PZWL) in relation with the XXIV Conference of the Polish Thoracic Society (Wisła, 7−10 May 2016) includes a number of state-of-art papers addressing key pulmonological issues [...
Apsidal motion and light a curve solution for eighteen SMC eccentric eclipsing binaries
Aims: The Danish 1.54-meter telescope at the La Silla observatory was used
for photometric monitoring of selected eccentric eclipsing binaries located in
the Small Magellanic Cloud. The new times of minima were derived for these
systems, which are needed for accurate determination of the apsidal motion.
Moreover, many new times of minima were derived from the photometric databases
OGLE and MACHO. Eighteen early-type eccentric-orbit eclipsing binaries were
studied.
Methods: Their (O-C) diagrams of minima timings were analysed and the
parameters of the apsidal motion were obtained. The light curves of these
eighteen binaries were analysed using the program PHOEBE, giving the light
curve parameters. For several systems the additional third light also was
detected.
Results: We derived for the first time and significantly improved the
relatively short periods of apsidal motion from 19 to 142 years for these
systems. The relativistic effects are weak, up to 10% of the total apsidal
motion rate. For one system (OGLE-SMC-ECL-0888), the third-body hypothesis was
also presented, which agrees with high value of the third light for this system
detected during the light curve solution.Comment: 8 pages, 5 figures, 4 tables, plus the appendix data tables with
times of minima. Published in 2014A&A...572A..71
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