Materiały konferencyjne (WF)

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    Study of meteoroid stream identification methods
    (Cambridge University Press, 2010) Rudawska, Regina; Jopek, Tadeusz J.
    We have tested the reliability of various meteoroid streams identification methods. We used a numerically generated set of meteoroid orbits (a stream component and a sporadic background) that were searched for streams using several methods.
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    Radio meteor data from the Hissar observatory in the IAU MDC database
    (Tajik Technical University, 2020) Narziev, M.; Chebotariev, R. P.; Jopek, T. J.; Neslusan, L. Z.; Porubcan, V.; Svoren, J.; Khujanazarov, H.F.
    The article deals with the results of a two-dimensional distribution of meteoroids over the equatorial and ecliptic coordinates of the radiants, velocities, and radio magnitudes of meteoroids. The coordinates of the radiant and the angular orbital elements correspond to the J2000 epoch. Radio magnitudes of meteors are concentrated in the range 0 ÷ 5.5 mag with a maximum at 3.3 mag. The data of 8916 radiometeors obtained by radar observations from 4 points at the Gissar Astronomical Observatory, Dushanbe, Tajikistan, have been added to the database of the Meteor Data Center of the International Astronomical Union.
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    On the atmospheric dynamics of the Tunguska cosmic body
    (ESA Publication Division, 2001-11) Foschini, Luigi; Longo, Giuseppe; Jopek, Tadeusz J.; Froeschle, Christiane; Gonczi, Robert; Michel, Patric
    We studied the available scientific literature on the Tunguska event of 30 June 1908 to obtain parameter sets of the Tunguska Cosmic Body atmospheric dynamics. We performed a comparative analysis by means of available theoretical models and with the help of interplanetary dynamics, and we excluded unphysical orbits. Our results indicate a very high probability that the TCB was an asteroid.
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    The Near Earth Asteroid associations
    (IAU Publisher: Cambridge Universtity Press, 2018-09) Jopek, Tadeusz
    We searched for associations (not for families) amongst the near Earth asteroids (NEAs) and, similarly as in our previous study (Jopek 2011, Jopek 2012), a dozen groups of 10 or more members was found with high statistical reliability. We present some details of our most numerous finding, association Anza ’2061’ which, at the moment, incorporates 191 members.
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    Current status of the IAU MDC Meteor Showers Database
    (Wydawnictwo Naukowe Uniwersytetu im. Adama Mickiewicza w Poznaniu, 2014) Jopek, Tadeusz J.; Kanuchova, Zuzana
    During the General Assembly of the IAU in Beijing in 2012, at the business meeting of Commission 22 the list of 31 newly established showers was approved and next o cially accepted by the IAU. As a result, at the end of2013, the list of all established showers contained 95 items. The IAU MDC Working List included 460 meteor showers, among them 95 had pro tempore status. The List of Shower Groups contained 24 complexes, three of them had established status. Jointly, the IAU MDC shower database contained data of 579 showers.
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    Meteor stream identification: a new approach. Application to 3675 radio meteors
    (Astronomical Institute of the Slovak Academy of Sciences, 1999) Jopek, T.J.; Valsecchi, G.B.; Froeschle, Cl.
    The new criterion DN for meteoroid streams identification, based on variables directly linked to observations, was applied to a set of radio meteors observed in Adelaide. 28 streams, combinning 28% of the 3675 orbits have been detected. 8 streams have a single crossing point with the Earth orbit, 20 groups were identified as twin showers.
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    TV meteor streams searching
    (Astronomical Institute Slovak Academy of Sciences, Bratislava, 1993) Jopek, Tadeusz J.
    Using a modified D-criterion (threshold Do=0.2), among 531 TV meteor orbits, 23 streams has been identified. Adout 30% of the orbits belongs to the stream component. Only 3 streams have orbits inclined more than 30deg. Four streams have reciprocal orbits. The major stream Herculids shown to be a complex structure, sensitive on the choice of the D- threshold value. The Taurids complex differs slightly from the photographic one. The theta Piscids stream has very small orbit, the mean semi-major axis equals to 0.79AU. This stream seems to be TV component of the Eccentrides system, but with Do=0.21 the theta Piscids have joined S. Taurids. The TV Orionids appeared in two branches. One of them includes a single orbit which belongs to the eta Aquariids.
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    Carbon Ion Radiotherapy - Advantages, Technical Aspects and Perspectives
    (Joint Institute for Nuclear Research, 2013) Kubiak, Tomasz
    Carbon ion radiotherapy is a groundbreaking method of treatment radioresistant tumors situated close to critical organs. The article presents the physical basis of carbon ion therapy, methods of generation and acceleration of heavy ions, systems of forming and exact positioning of the therapeutic beam. Intensity modulated particle therapy and raster scanning technique allow optimum compatibility between the irradiated volume and target volume. By dint of such methods minimum exposure of critical structures is possible. An important aspect of the treatment process is the monitoring of patient's position during the irradiation. It is possible by means of the modern imaging techniques such as PET-CT. Increase of the availability of heavy ion therapy and its development are big challenges for the physicists of the most prestigious research centers in the world.
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    NMR imaging and cryoporometry of swelling clays
    (EGU General Assembly, 2010) Dvinskikh, Sergey V; Szutkowski, Kosma; Petrov, Oleg V; Furó, István
    Compacted bentonite clay is currently attracting attention as a promising “self-sealing” buffer material to build in-ground barriers for the encapsulation of radioactive waste. It is expected to fill up the space between waste canister and surrounding ground by swelling and thus delay flow and migration from the host rock to the canister. In environmental sciences, evaluation and understanding of the swelling properties of pre-compacted clay are of uttermost importance for designing such buffers. Major goal of present study was to provide, in a non-invasive manner, a quantitative measure of bentonite distribution in extended samples during different physical processes in an aqueous environment such as swelling, dissolution, and sedimentation on the time scale from minutes to years. The propagation of the swelling front during clay expansion depending on the geometry of the confining space was also studied. Magnetic resonance imaging and nuclear magnetic resonance spectroscopy were adapted and used as main experimental techniques. With this approach, spatially resolved movement of the clay/water interface as well as clay particle distributions in gel phase can be monitored [1]. Bulk samples with swelling in a vertical tube and in a horizontal channel were investigated and clay content distribution profiles in the concentration range over five orders of magnitude and with sub-millimetre spatial resolution were obtained. Expansion rates for bulk swelling and swelling in narrow slits were compared. For sodium-exchanged montmorillonite in contact with de-ionised water, we observed a remarkable acceleration of expansion as compared to that obtained in the bulk. To characterize the porosity of the clay a cryoporometric study [2] has been performed. Our results have important implications to waste repository designs and for the assessment of its long-term performance. Further research exploring clay–water interaction over a wide variety of clay composition and water ionic strength as well as investigating the effect of the confining geometry and material surface properties seem to be worth to pursue.
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    Ampere NMR School 2008 Abstracts
    (Wydział Fizyki Uniwersytet im. Adama Mickiewicza w Poznaniu, 2008-06) Jurga, Stefan