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Безотражательное распространение акустических волн в атмосфере Земли
Письма в Журнал экспериментальной и теоретической физики. 2011. Т. 93. № 10. С. 625–628.
The vertical propagation of acoustic waves in the inhomogeneous compressible atmosphere has been studied in the framework of the linear theory of ideal hydrodynamics. It has been shown that the initial equations under certain conditions can be reduced to the Klein–Gordon equation with constant coefficients. Its solutions describe traveling waves with a variable amplitude and wavenumber that are not reflected in the atmosphere despite its strong inhomogeneity. The wave energy flux at such reflectionless profiles holds, providing the possibility of the energy transfer to high altitudes. It has been shown that the Standard Earth Atmosphere is approximated well by four reflectionless profiles withsmall jumps in the gradient of the speed of sound. It is found that the Earth’s atmosphere is almost transparent in a wide frequency range; this feature explains the observation data and conclusions made on the basis of numerical solutions in the framework of the initial equations.
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Russian
Piontkovski D., / Series arXiv "math". 2026.
A noncommutative projective variety is defined, following Artin and Zhang, by a graded coherent algebra 𝐴. The category of coherent sheaves is then the quotient qgr(𝐴) of the category of finitely presented graded modules by the subcategory of torsion modules. We consider the categorical and polynomial entropies of the Serre twist, that is, of the ...
Added: June 23, 2026
Piontkovski D., / Series arXiv "math". 2025.
If a symmetric multilinear algebra is weakly nil, then it is Engel. This result may be regarded as an infinite-dimensional analogue of the well-known Jacobian theorem, which states that if a polynomial mapping has a polynomial inverse, then its Jacobian matrix is invertible. This refines a theorem of Gerstenhaber and partially answers a question posed ...
Added: June 23, 2026
Shipilov F., Barnyakov A., Ivanov A. et al., / Series Physics "arxiv.org". 2026.
A fast simulation of the detector response is a vital task in high-energy physics (HEP). Traditional Monte-Carlo methods form the backbone of modern particle physics simulation software but are computationally expensive. We present a machine-learning-based approach to fast simulation of the Focusing Aerogel Ring Imaging Cherenkov (FARICH) detector response. Given a particle track and momentum, ...
Added: May 19, 2026
Гущина В. А., / Series chemrxiv-2023-vpzhz-v2 "ChemRxiv". 2023.
All-inorganic perovskite CsPbBr3 and Cs4PbBr6 nanoparticles are being intensively studied due to their unique properties and wide range of applications; however, however, the nature of their optical properties is not yet fully understood due to the difficulty of synthesis of singlephase nanoparticles. In this article we describe the features of the synthesis of single-phase particles ...
Added: May 14, 2026
Derkacheva A., Sakirkina M., Kraev G. et al., /. 2026.
Comprehensive data on natural hazards and their consequences are crucial for effective for risk assessment, adaptation planning, and emergency response. However, many countries face challenges with fragmented, inconsistent, and inaccessible data, particularly regarding local-scale events. To address this data gap in Russia, we developed an end-to-end processing pipeline that scrapes news from various online sources, ...
Added: April 28, 2026
Pilé I., Deng Y., Shchur L., / Series arXiv "math". 2026. No. 2604.10254.
We investigate the spatial overlap of successive spin configurations in Markov chain Monte Carlo simulations using the local Metropolis algorithm and the Svendsen-Wang and Wolff cluster algorithms. We examine the dynamics of these algorithms for two models in different universality classes: the Ising model and the Potts model with three components. The overlap of two ...
Added: April 20, 2026
Gabdullin N., Androsov I., / Series Computer Science "arxiv.org". 2026.
Label prediction in neural networks (NNs) has O(n) complexity proportional to the number of classes. This holds true for classification using fully connected layers and cosine similarity with some set of class prototypes. In this paper we show that if NN latent space (LS) geometry is known and possesses specific properties, label prediction complexity can ...
Added: April 2, 2026
Sorokin K., Beketov M., Онучин А. et al., / arxiv.org. Серия cs.SI "Social and Information Networks ". 2025.
Community detection in complex networks is a fundamental problem, open to new approaches in various scientific settings. We introduce a novel community detection method, based on Ricci flow on graphs. Our technique iteratively updates edge weights (their metric lengths) according to their (combinatorial) Foster version of Ricci curvature computed from effective resistance distance between the ...
Added: January 15, 2026
Petrovanov I., Sergeev A., / Series Computer Science "arxiv.org". 2025. No. 2512.18332.
Transport coding reduces message delay in packet-switched networks by introducing controlled redundancy at the transport layer: original packets are encoded into coded packets, and the message is reconstructed after the first successful deliveries, effectively shifting latency from the maximum packet delay to the -th order statistic. We present a concise, reproducible discrete-event implementation of transport coding in OMNeT++, including ...
Added: December 24, 2025
Hessian-based lightweight neural network for brain vessel segmentation on a minimal training dataset
Меньшиков И. А., Бернадотт А. К., Elvimov N. S., / Series arXie "Statistical mechanics". 2025.
Accurate segmentation of blood vessels in brain magnetic resonance angiography (MRA) is essential for successful surgical procedures, such as aneurysm repair or bypass surgery. Currently, annotation is primarily performed through manual segmentation or classical methods, such as the Frangi filter, which often lack sufficient accuracy. Neural networks have emerged as powerful tools for medical image ...
Added: December 1, 2025
Vitaly A. Kuzkin, Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 2023 Vol. 107 No. 6
We study propagation of wave packets through the interface between two dissimilar harmonic chains with on-site potentials (e.g., chains lying on elastic foundations). An expression for the transmission coefficient, relating energies of the incident and transmitted wave packets is derived using two different approaches. Without elastic foundation, the transmission coefficient monotonically decreases with increasing wave ...
Added: January 30, 2025
Петрухин Н.С., Пелиновский Е. Н., Талипова Т. Г., Известия высших учебных заведений. Радиофизика 2023 Т. 66 № 5-6 С. 472–482
We study the vertical propagation of acoustic waves in a strongly inhomogeneous atmosphere. The
class of monotonically varying profiles for sound velocity, gas density, and gas pressure, for which acoustic
waves can propagate with no reflection outside the framework of the classical WKB approximation,
is found. Such class of profiles, called non-reflected ones, is obtained by transforming the ...
Added: December 4, 2023
Popova V., Matveeva T., Daria Bokuchava, Environmental Sciences Proceedings 2022 Vol. 19 No. 1 Article 57
Analysis of climatic characteristics, Palmer Drought Severity Index, and large-scale river runoff based on observational data (CRUTEM.5, GISSTEMP v4, CRU TS4.05, CRU-scPDSI) and 20th century reanalysis (ERA20C, CERA20C) shows that the early 20th century warming period, in particular the 1930s, on the East-European Plain was marked by the strong long-lasting drought that has no analogues ...
Added: September 20, 2023
D. D. Bokuchava, Semenov V. A., Earth-Science Reviews 2021 Vol. 222 Article 103820
The Early 20th Century Warming (ETCW) in the northern high latitudes was comparable in magnitude to the present-day warming yet occurred at a time when the growth in atmospheric greenhouse gases was rising significantly less than in the last 40 years. The causes of ETCW remain a matter of debate. The key issue is to assess ...
Added: September 20, 2023
Kazakov A., Chaos 2020 Vol. 30 No. 1 Article 011105
We study the phenomenon of a collision of a Hénon-like attractor with a Hénon-like repeller leading to the emergence of mixed dynamics in the model describing the motion of two point vortices in a shear flow perturbed by an acoustic wave. The mixed dynamics is a recently discovered type of chaotic behavior for which a ...
Added: March 8, 2021
Zotov L., Sidorenkov N. S., Bizouard C., В кн.: Известия главной астрономической обсерватории в ПулковеВып. 222: ТРУДЫ V Пулковской молодежной астрономической конференции.: СПб.: ГАО РАН, 2015. С. 41–48.
It is well known, that inclination of the Earth rotation axis to the ecliptic plain defines the maxima
and minima declination of the Sun on the days of solstices. According to the Milankovitch theory
variations of this parameter are one of the causes of the glacial periods. Some facts show, that motions
of the Moon from equator to ...
Added: March 5, 2016
Savina O., Gromov E., Tyutin V. V., Геомагнетизм и аэрономия 2015 Т. 55 № 5 С. 675–679
The possibility of the existence of the solitary internal gravity waves on the Earth's thermosphere heights is discussed. Analytical results are obtained with local approximation weak
nonisothermal atmosphere. For internal gravity waves is derived Korteweg-de Vries equation with the heterogeneity, nonlinearity and dissipation. Theoretical
results are used to interpret the basic parameters of solitary traveling ionospheric disturbances ...
Added: July 2, 2015
М.: ГЕОС, 2014.
Конференция организована при поддержке Президиума Российской Академии Наук и Российского Фонда Фундаментальных Исследований (проект № 13-05-06016-г). ...
Added: October 28, 2014
Petrukhin N., Pelinovsky E., Batsyna E. K., Astronomy Letters 2012 Vol. 38 No. 6 P. 388–393
The possibility that vertical acoustic waves with frequencies lower than the cutofffrequency corresponding to the temperature minimum pass this minimum is investigated. It is shown that the averaged temperature profile in the solar atmosphere can be approximated by several so-called reflectionless profiles onwhich the acousticwaves propagate without internal reflection. The possibility of the penetration of ...
Added: March 23, 2014
Беспалов П. А., Savina O., Известия высших учебных заведений. Радиофизика 2014 Т. 57 № 2 С. 129–136
Equations for the wave perturbations of velocity and pressure in a nonisothermal atmosphere are considered. It is noted that the pressure perturbation has singularities near the altitude where the equality of the horizontal phase velocity of the perturbation and sound velocity in the medium is fulfilled. At this altitude, a thin atmospheric layer with finite ...
Added: December 6, 2013
Batsyna E. K., В кн.: XVII Нижегородская сессия молодых ученых. Естественные, математические науки.: Н. Новгород: НИУ РАНХиГС, 2012. С. 177–180.
Рассматривается распространение акустического излучения в плоскослоистой атмосфере Солнца. Показана возможность проникновения волн на большие расстояния. ...
Added: February 18, 2013
Petrukhin N., Pelinovsky E., Batsyna E. K., Геомагнетизм и аэрономия 2012 Т. 52 № 6 С. 854–860
The vertical wave propagation in an inhomogeneous compressible atmosphere is studied in the framework of a linear theory. Under specific conditions imposed on atmospheric parameters, solutions can be found in the form of propagating waves with variable amplitudes and wave numbers that do not reflect in the atmosphere in spite of its strong inhomogeneity. Model ...
Added: November 9, 2012
Petrukhin N., Pelinovsky E., Batsyna E. K., Письма в Астрономический журнал 2012 Т. 38 № 6 С. 439–445
The possibility that vertical acoustic waves with frequencies lower than the cutoff frequency corresponding to the temperature minimum pass this minimum is investigated. It is shown that the averaged temperature profile in the solar atmosphere can be approximated by several so-called reflectionless profiles on which the acoustic waves propagate without internal reflection. The possibility of ...
Added: May 3, 2012