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Search Results: 1 - 10 of 130328 matches for " V. Sliusar "
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One-dimensional model of cosmological perturbations: direct integration in the Fourier space
V. M. Sliusar,V. I. Zhdanov
Physics , 2012,
Abstract: We propose a method of calculation of the power spectrum of cosmological perturbations by means of a direct numerical integration of hydrodynamic equations in the Fourier space for a random ensemble of initial conditions with subsequent averaging procedure. This method can be an alternative to the cosmological N-body simulations. We test realizability of this method in case of one-dimensional motion of gravitating matter pressureless shells. In order to test the numerical simulations, we found an analytical solution which describes one-dimensional collapse of plane shells. The results are used to study a nonlinear interaction of different Fourier modes.
Caustic Crossing Events and Source Models in Gravitational Lens Systems
A. N. Alexandrov,V. M. Sliusar,V. I. Zhdanov
Physics , 2011,
Abstract: High amplification events (HAEs) are common phenomena in extragalactic gravitational lens systems (GLSs), where the multiple images of a distant quasar are observed through a foreground galaxy. There is a considerable brightness magnification in one of the quasar images during HAE. Grieger, Kayser, and Refsdal (1988) proposed to use HAEs to study the central regions of quasars in GLSs. In this paper, we consider some problems concerning the identification of different source types on the basis of the HAE observations. We compare the results of light curve simulations to estimate a feasibility to distinguish different source models in GLSs. Analytic approximation methods yielding solutions of the lens equation in a vicinity of fold caustic crossing events are presented. The results are used to obtain amplification factors, which the higher-order corrections for the Gaussian, power-law, and limb-darkening models of a source take into account.
Analytical Methods in Gravitational Microlensing
V. I. Zhdanov,A. N. Alexandrov,E. V. Fedorova,V. M. Sliusar
ISRN Astronomy and Astrophysics , 2012, DOI: 10.5402/2012/906951
Abstract:
Analytical Methods in Gravitational Microlensing
V. I. Zhdanov,A. N. Alexandrov,E. V. Fedorova,V. M. Sliusar
ISRN Astronomy and Astrophysics , 2012, DOI: 10.5402/2012/906951
Abstract: We discuss analytical results dealing with photometric and astrometric gravitational microlensing. The first two sections concern approximation methods that allow us to get solutions of the general lens equation near fold caustics and cusp points up to any prescribed accuracy. Two methods of finding approximate solutions near the fold are worked out. The results are applied to derive new corrections to total amplifications of critical source images. Analytic expressions are obtained in case of the Gaussian, power-law, and limb-darkening extended source models; here we present the first nonzero corrections to the well-known linear caustic approximation. Possibilities to distinguish different source models in observations are discussed on the basis of statistical simulations of microlensed light curves. In the next section, we discuss astrometric microlensing effects in various cases of extended sources and extended lenses, including a simple model of weak statistical microlensing by extended dark matter clumps. Random walks of a distant source image microlensed by stochastic masses are estimated. We note that the bulk motion of foreground stars induces a small apparent rotation of the extragalactic reference frame. Compact analytical relations describing the statistics of such motions are presented. 1. Introduction Gravitational lensing theory contains a number of nice analytical results and beautiful theorems, which give a description of the observed effects on the level of quality and form a basis for quantitative calculations [1, 2]. This theory is based on the general relativity that describes the propagation of electromagnetic radiation in a curved space-time. Two effects are most important: the Einsteinian light bending in the gravitational field and the gravitational time delay. These effects are described by simple formulas that can be found in any textbook on relativistic gravity. However, their use in a particular gravitational lens system (GLS) can be rather complicated, and there is a considerable need for improvement of numerical methods and analytical studies. The present article deals mainly with some of the topics of the latter subject. We believe that there exists a considerable number of interesting problems concerning GLS that can be solved either without using extensive computations or where such computations can be reduced to a minimum. One of the most spectacular effects in observations of GLS is a considerable brightness enhancement in one of the source images due to the microlensing [1–3]; this is often referred to as a high
Thermo- and pH-sensitive Hydrogels with Incorporated Multi-Walled Carbon Nanotubes
Korotych O.I.,Goncharuk A.I.,Sliusar Yu.M.,Samchenko Yu.M.
Proceedings of the International Conference Nanomaterials : Applications and Properties , 2013,
Abstract: Carbon nanotubes (CNTs) attract great attention due to the unique combination of physical, chemical, electrical and mechanical properties which have high potential for design of nanocomposite materials with customized properties (electromagnetic shielding, high strength and electroconductivity materials), actuators (e.g. artificial muscles and tissues), sensors, components of microfluidic devices, etc. Usage of CNT in practical applications is limited by their lower solubility in most solvents. Remaining primary agglomerates of NT not only increase the amount of filler needed for percolation, but also act as imperfections under mechanical stress. Therefore, in this investigation, the influence of surfactant type and its concentration, along with sonication treating time on sedimentation behavior of multi-walled carbon nanotubes was investigated. To a greater extent, the influence of monomer composition, surface-active substances, and carbon nanotubes on gelation and physicochemical properties of thermo- and pH-sensitive hydrogels and hydrogel nanocomposites based on N-isopropylacrylamide with carbon nanotubes were investigated too.
Astrophysical and cosmological problems of invisible mass and dark energy in the Universe
P. Belli,L. A. Berdina,R. Bernabei,A. Bogdan,R. S. Boiko,A. Yu. Burgazli,F. Cappella,R. Cerulli,D. M. Chernyak,F. A. Danevich,A. d'Angelo,M. V. Eingorn,S. H. Fakhr,E. Fedorova,E. N. Galashov,A. Giuliani,B. I. Hnatyk,A. Incicchitti,G. Ivashchenko,V. V. Kobychev,O. O. Kobzar,H. Kraus,B. N. Kropivyansky,A. V. Kudinova,Yu. A. Kulinich,M. Laubenstein,V. V. Marchenko,S. Marnieros,V. B. Mikhailik,A. A. Minakov,V. M. Mokina,L. L. Nagornaya,A. S. Nikolaiko,C. Nones,B. S. Novosyadlyj,E. Olivieri,V. O. Pelykh,D. V. Poda,R. B. Podviyanuk,O. G. Polischuk,O. N. Sergijenko,V. N. Shlegel,V. M. Shulga,V. M. Sliusar,O. B. Sushchov,Y. V. Taistra,M. Tenconi,O. Torbaniuk,V. I. Tretyak,V. S. Tsvetkova,V. G. Vakulik,Ya. V. Vasiliev,A. Vasylenko,O. Vasylenko,V. I. Zhdanov,A. I. Zhuk
Physics , 2013,
Abstract: The Workshop on results of the Project Kosmomikrofizyka-2 (Astroparticle Physics) of the National Academy of Sciences (NAS) of Ukraine "Astrophysical and cosmological problems of invisible mass and dark energy in the Universe" was held on November 21-22, 2012 in the Institute for Nuclear Research, Kyiv, Ukraine (http://lpd.kinr.kiev.ua/kmf12). This Project was carried out during three years (2010-2012) by scientists from various universities and institutes of the National Academy of Sciences of Ukraine; it was a logical continuation of the previous scientific program of the NAS of Ukraine "Researches of structure and composition of the Universe, hidden mass and dark energy (Kosmomikrofizyka)" in 2007-2009. These programs were devoted to theoretical and experimental investigations in astronomy, astrophysics, cosmology, physics of atomic nuclei and particle physics, which are related with the problems of dark matter and dark energy in the Universe.
The SST-1M camera for the Cherenkov Telescope Array
E. J. Schioppa,F. Cadoux,A. Christov,D. della Volpe,Y. Favre,M. Heller,T. Montaruli,A. Porcelli,M. Rameez,I. Troyano Pujadas,W. Bilnik,J. Blocki,L. Bogacz,T. Bulik,M. Curylo,M. Dyrda,A. Frankowski,L. Grudniki,M. Grudzinska,B. Idzkowski,M. Jamrozy,M. Janiak,J. Kasperek,K. Lalik,E. Lyard,E. Mach,D. Mandat,A. Marszalek,J. Michaowski,R. Moderski,A. Neronov,J. Niemiec,M. Ostrowski,P. Pasko,M. Pech,E. Prandini,P. Rajda,P. Schovanek,K. Seweryn,K. Skowron,V. Sliusar,M. Sowinski,L. Stawarz,M. Stodulska,M. Stodulski,S. Toscano,R. Walter,M. Wiecek,A. Zagdanski,K. Zietara,P. Zychowski
Physics , 2015,
Abstract: The prototype camera of the single-mirror Small Size Telescopes (SST-1M) proposed for the Cherenkov Telescope Array (CTA) project has been designed to be very compact and to deliver high performance over thirty years of operation. The camera is composed of an hexagonal photo-detection plane made of custom designed large area hexagonal silicon photomultipliers and a high throughput, highly configurable, fully digital readout and trigger system (DigiCam). The camera will be installed on the telescope structure at the H. Niewodnicza{\'n}ski institute of Nuclear Physics in Krakow in fall 2015. In this contribution, we review the steps that led to the development of the innovative photo-detection plane and readout electronics, and we describe the test and calibration strategy adopted.
Prototype of the SST-1M Telescope Structure for the Cherenkov Telescope Array
J. Niemiec,W. Bilnik,J. B?ocki,L. Bogacz,J. Borkowski,T . Bulik,F. Cadoux,A. Christov,M. Cury?o,D. della Volpe,M. Dyrda,Y. Favre,A. Frankowski,?. Grudnik,M. Grudzińska,M. Heller,B. Id?kowski,M. Jamrozy,M. Janiak,J. Kasperek,K. Lalik,E. Lyard,E. Mach,D. Mandat,A. Marsza?ek,J. Micha?owski,R. Moderski,T. Montaruli,A. Neronov,M. Ostrowski,P. Pa?ko,M. Pech,A. Porcelli,E. Prandini,P. Rajda,M. Rameez,E. jr. Schioppa,P. Schovanek,K. Seweryn,K. Skowron,V. Sliusar,M. Sowiński,?. Stawarz,M. Stodulska,M. Stodulski,I. Troyano Pujadas,S. Toscano,R. Walter,M. Wi?cek,A. Zagdański,K. Zi?tara,P. ?ychowski for the SST-1M sub-consortium,the CTA Consortium
Physics , 2015,
Abstract: A single-mirror small-size (SST-1M) Davies-Cotton telescope with a dish diameter of 4 m has been built by a consortium of Polish and Swiss institutions as a prototype for one of the proposed small-size telescopes for the southern observatory of the Cherenkov Telescope Array (CTA). The design represents a very simple, reliable, and cheap solution. The mechanical structure prototype with its drive system is now being tested at the Institute of Nuclear Physics PAS in Krakow. Here we present the design of the prototype and results of the performance tests of the structure and the drive and control system.
Using muon rings for the optical throughput calibration of the SST-1M prototype for the Cherenkov Telescope Array
S. Toscano,E. Prandini,W. Bilnik,J. B?ocki,L. Bogacz,T. Bulik,F. Cadoux,A. Christov,M. Cury?o,D. della Volpe,M. Dyrda,Y. Favre,A. Frankowski,?. Grudnik,M. Grudzińska,M. Heller,B. Id?kowski,M. Jamrozy,M. Janiak,J. Kasperek,K. Lalik,E. Lyard,E. Mach,D. Mandat,A. Marsza?ek,J. Micha?owski,R. Moderski,T. Montaruli,A. Neronov,J. Niemiec,M. Ostrowski,P. Pa?ko,M. Pech,A. Porcelli,M. Rameez,P. Rajda,E. jr. Schioppa,P. Schovanek,K. Seweryn,K. Skowron,V. Sliusar,M. Sowiński,?. Stawarz,M. Stodulska,M. Stodulski,I. Troyano Pujadas,R. Walter,M. Wi?cek,A. Zagdański,K. Zi?tara,P. ?ychowski,for the CTA Consortium
Physics , 2015,
Abstract: Imaging Atmospheric Cherenkov Telescopes (IACTs) are ground-based instruments devoted to the study of very high energy gamma-rays coming from space. The detection technique consists of observing images created by the Cherenkov light emitted when gamma rays, or more generally cosmic rays, propagate through the atmosphere. While in the case of protons or gamma-rays the images present a filled and more or less elongated shape, energetic muons penetrating the atmosphere are visualised as characteristic circular rings or arcs. A relatively simple analysis of the ring images allows the reconstruction of all the relevant parameters of the detected muons, such as the energy, the impact parameter, and the incoming direction, with the final aim to use them to calibrate the total optical throughput of the given IACT telescope. We present the results of preliminary studies on the use of images created by muons as optical throughput calibrators of the single mirror small size telescope prototype SST-1M proposed for the Cherenkov Telescope Array.
Software design for the control system for Small-Size Telescopes with single-mirror of the Cherenkov Telescope Array
A. Porcelli for the CTA Consortium,for the SST-1M sub-consortium,:,W. Bilnik,J. B?ocki,L. Bogacz,J. Borkowski,T. Bulik,F. Cadoux,A. Christov,M. Cury?o,D. della Volpe,M. Dyrda,Y. Favre,A. Frankowski,?. Grudnik,M. Grudzińska,M. Heller,B. Id?kowski,M. Jamrozy,M. Janiak,J. Kasperek,K. Lalik,E. Lyard,E. Mach,D. Mandat,A. Marsza?ek,J. Micha?owski,R. Moderski,M. Rameez,T. Montaruli,A. Neronov,J. Niemiec,M. Ostrowski,P. Pa?ko,M. Pech,A. Porcelli,E. Prandini,P. Rajda,E. jr Schioppa,P. Schovanek,K. Seweryn,K. Skowron,V. Sliusar,M. Sowiński,?. Stawarz,M. Stodulska,M. Stodulski,I. Troyano Pujadas,S. Toscano,R. Walter,M. Wi?cek,A. Zagdański,K. Zi?tara,P. Zychowski
Physics , 2015,
Abstract: The Small-Size Telescope with single-mirror (SST-1M) is a 4 m Davies-Cotton telescope and is among the proposed telescope designs for the Cherenkov Telescope Array (CTA). It is conceived to provide the high-energy ($>$ few TeV) coverage. The SST-1M contains proven technology for the telescope structure and innovative electronics and photosensors for the camera. Its design is meant to be simple, low-budget and easy-to-build industrially. Each device subsystem of an SST-1M telescope is made visible to CTA through a dedicated industrial standard server. The software is being developed in collaboration with the CTA Medium-Size Telescopes to ensure compatibility and uniformity of the array control. Early operations of the SST-1M prototype will be performed with a subset of the CTA central array control system based on the Alma Common Software (ACS). The triggered event data are time stamped, formatted and finally transmitted to the CTA data acquisition. The software system developed to control the devices of an SST-1M telescope is described, as well as the interface between the telescope abstraction to the CTA central control and the data acquisition system.
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