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287 results on '"Tsvetkov, D."'

7. Observations of Supernova SN 2018zd

Author

Tsvetkov, D. Yu., Goranskij, V. P., Barsukova, E. A., Valeev, A. F., Volkov, I. M., Pavlyuk, N. N., Shugarov, S. Yu., Shatsky, N. I., Vozyakova, O. V., and Echeistov, V. A.

Published
2022
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10. SMALL MOTIONS OF AN IDEAL STRATIFIED FLUID IN A BASIN COVERED BY ICE

Author

Kopachevsky, N. D. and Tsvetkov, D. O.

Subjects
Mathematics
Abstract

We study the problem on small motions of the ideal stratified fluid with a free surface partially covered by the crushed ice. The crushed ice is supposed to be ponderable particles of a matter floating on the free surface. These particles do not interact with each other during oscillations of the free boundary (or this interaction is negligible) and stay on the surface during these oscillations. Using the method of orthogonal projection of boundary-value conditions on the free surface and introducing auxiliary problems, we reduce the original initial-boundary problem to the equivalent Cauchy problem for a second-order differential equation in a Hilbert space. We obtain conditions providing the existence of a solution strong with respect to time of the initial-boundary problem describing the evolution of this hydraulic system., CONTENTS Introduction 887 1. Statement of the Problem. Passage to Operator Equations 888 2. Strong Solvability Theorem 897 References 904 Introduction New demands of applied sciences motivate the interest to [...]

Published
2022
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12. Mixing Enthalpy Estimation for CsX–PbX2 Melts (X = Cl, Br) by Differential Scanning Calorimetry.

Author

Tsvetkov, D. S., Malyshkin, D. A., Mazurin, M. O., Sereda, V. V., and Zuev, A. Yu.

Abstract

A comparatively simple method for estimating the mixing enthalpy of melts by differential scanning calorimetry using standard equipment is proposed. The enthalpies of mixing of CsX–PbX2 (X = Cl, Br) melts are determined by this method. The measured values of mixing enthalpy in the CsCl–PbCl2 system are in good agreement with those obtained by means of independent measurements. For the CsBr–PbBr2 system, the enthalpy of mixing was measured for the first time. The similar values of mixing enthalpy were found for both studied systems. [ABSTRACT FROM AUTHOR]

Published
2024
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22. The bright Type IIP SN 2009bw, showing signs of interaction

Author

Inserra, C., Turatto, M., Pastorello, A., Pumo, M. L., Baron, E., Benetti, S., Cappellaro, E., Taubenberger, S., Bufano, F., Elias-Rosa, N., Zampieri, L., Harutyunyan, A., Moskvitin, A. S., Nissinen, M., Stanishev, V., Tsvetkov, D. Y., Hentunen, V. P., Komarova, V. N., Pavlyuk, N. N., Sokolov, V. V., and Sokolova, T. N.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

We present photometry and spectroscopy of the type IIP supernova 2009bw in UGC 2890 from few days after the outburst to 241 days. The light curve of SN 2009bw during the photospheric phase is similar to that of normal SNe IIP but with brighter peak and plateau (Mmax R = -17.82 mag, Mplateau R = -17.37 mag). The luminosity drop from the photospheric to the nebular phase is one of the fastest ever observed, ~2.2 mag in about 13 days. The radioactive tail of the bolometric light curve indicates that the amount of ejected 56 Ni is \approx 0.022 M\odot. The photospheric spectra reveal high velocity lines of H{\alpha} and H{\beta} until about 105 days after the shock breakout, suggesting a possible early interaction between the SN ejecta and pre-existent circumstellar material, and the presence of CNO elements. By modeling the bolometric light curve, ejecta expansion velocity and photospheric temperature, we estimate a total ejected mass of 8-12M\odot, a kinetic energy of ~0.3 foe and an initial radius of ~ 3.6 - 7 \times 10^13 cm., Comment: Accepted for publication in MNRAS, 19 pages, 13 figures, 9 tables

Published
2012
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23. Fundamental and technological aspects of thermochemical expansion of proton-conducting oxides: a case study of BaSn1−xScxO3−δ.

Author

Starostin, G. N., Tsvetkov, D. S., Starostina, I. A., Sereda, V. V., Akopian, M. T., Malyshkin, D. A., Ivanov, I. L., Murashkina, A. A., Zuev, A. Yu, and Medvedev, D. A.

Abstract

Proton-conducting electrolytes (PCEs) are extensively researched materials utilized in solid oxide electrochemical cells with various operating principles. The high ionic (protonic) transport of PCEs offers superior performance of such cells at reduced temperatures (400–600 °C). However, chemical-related deformations (strains) caused by the materials' hydration/dehydration pose serious technological challenges for fabricating multilayered (cer-cer, cer-met, and cer-glass) assemblies. Therefore, studying both thermal and chemical expansions of PCEs is crucial. This work presents in-depth high-temperature characterization of Sc-doped BaSnO3 compounds (BaSn1−xScxO3−δ) in terms of their thermochemical expansion behavior. This characterization includes high-temperature X-ray diffraction and dilatometry analyses under various measuring conditions. On one hand, the collected data can serve as technological characteristics for the selection of appropriate functional materials. On the other hand, the thermochemical expansion data can be used to evaluate the thermodynamic parameters (enthalpy and entropy of hydration) and transport parameters (water chemical diffusion coefficient and chemical surface exchange constant) of PCEs. The latter was shown in the present work for the first time. This paves a new way to reveal the relationships between the composition, structure, thermochemical response, and transport properties of complex oxides capable of reversible water uptake. [ABSTRACT FROM AUTHOR]

Published
2024
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37. Critical assessment of thermodynamic properties of perovskite-type cesium lead chloride CsPbCl3.

Author

Tsvetkov, D. S., Mazurin, M. O., Sereda, V. V., Ivanov, I. L., Malyshkin, D. A., and Zuev, A. Yu.

Subjects
*CESIUM compounds, *HEAT of formation, *THERMODYNAMIC functions, *VALUATION of real property, *CESIUM, *ELECTRIC batteries
Abstract

The results of thermochemical study of the CsPbCl3 formation thermodynamics available in literature were critically evaluated by comparison with those calculated from the temperature dependence of EMF of galvanic cells involving CsPbCl3 as well as with the newly obtained solution calorimetric data. The origin of the discrepancy between the values of standard formation enthalpy reported by different scientific groups was identified. Redetermined solution enthalpy of CsPbCl3 in dimethyl sulfoxide allowed correcting the earlier reported value of the standard formation enthalpy of CsPbCl3. As a result, the following consistent set of the thermodynamic functions for CsPbCl3 was obtained: Δ f H 298 ∘ = (–810.3 ± 0.4) kJ mol−1, S 298 ∘ = (270.1 ± 4.3) J mol−1 K−1. [ABSTRACT FROM AUTHOR]

Published
2022
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38. Critical assessment of thermodynamic properties of perovskite-type cesium lead chloride CsPbCl3.

Author

Tsvetkov, D. S., Mazurin, M. O., Sereda, V. V., Ivanov, I. L., Malyshkin, D. A., and Zuev, A. Yu.

Subjects
CESIUM compounds, HEAT of formation, THERMODYNAMIC functions, VALUATION of real property, CESIUM, ELECTRIC batteries
Abstract

The results of thermochemical study of the CsPbCl3 formation thermodynamics available in literature were critically evaluated by comparison with those calculated from the temperature dependence of EMF of galvanic cells involving CsPbCl3 as well as with the newly obtained solution calorimetric data. The origin of the discrepancy between the values of standard formation enthalpy reported by different scientific groups was identified. Redetermined solution enthalpy of CsPbCl3 in dimethyl sulfoxide allowed correcting the earlier reported value of the standard formation enthalpy of CsPbCl3. As a result, the following consistent set of the thermodynamic functions for CsPbCl3 was obtained: Δ f H 298 ∘ = (–810.3 ± 0.4) kJ mol−1, S 298 ∘ = (270.1 ± 4.3) J mol−1 K−1. [ABSTRACT FROM AUTHOR]

Published
2022
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41. Photometric observations of the supernova 2009nr

Author

Tsvetkov, D. Yu., Balanutsa, P. V., Lipunov, V. M., Volkov, I. M., Tuchin, O. A., Kudelina, I. P., Pruzhinskaya, M. V., Gorbovskoy, E. S., Kornilov, V. G., Belinskii, A. A., Tyurina, N. V., Yurkov, V. V., Sergienko, Yu. P., Tlatov, A. G., Parkhomenko, A. V., Dormidontov, D. V., Senik, V. A., and Krushinskii, V. V.

Published
2011
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