Filtering Features of Long Acoustic-Gravity Waves in a Windless Atmosphere
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 mass is concentrated. The wave perturbations do not penetrate to a higher level. The presence of a singularity in the wave perturbation of pressure was numerically confirmed for the actual altitude temperature profiles of the atmosphere.
One of natural combinations of Kripke complete modal logics is the product, an operation that has been extensively investigated over the last 15 years. In this paper we consider its analogue for arbitrary modal logics: to this end, we use product-like constructions on general frames and modal algebras. This operation was first introduced by Y. Hasimoto in 2000; however, his paper remained unnoticed until recently. In the present paper we quote some important Hasimoto’s results, and reconstruct the product operation in an algebraic setting: the Boolean part of the resulting modal algebra is exactly the tensor product of original algebras (regarded as Boolean rings). Also, we propose a filtration technique for Kripke models based on tensor products and obtain some decidability results.
Natural oscillations of the entire nonisothermal solar atmosphere are analysed. Such oscillations are probably related to the acoustic gravity wave. Analytical and numerical solutions describing acoustic gravity wave perturbations in the entire solar atmosphere are studied. Based on the model temperature profile, we find the spatio-temporal dependence for the linear acoustic gravity wave characteristics. The performed analysis using the approximate local method showed a possibility for the existence of instability of the acoustic gravity wave in the nonisothermal atmosphere. Such an instability develops at frequencies and spatial scales typical for the vertical five-minute oscillation of the solar atmosphere.
This article is about filtration system of former soviet POWs, it evolution during the war
Peculiarities of acoustic-gravity wave near the solar atmosphere transition region are analysed. An investigation is based on an original characteristic relation of waves in a two layers model with a temperature jump. Special attention is paid to an analysis of the properties of the surface waves, generated by the source of mass, which crosses the solar atmosphere transition region. An exact analytical solution of this problem, which involves several modes propagating along the boundary, is found. It is shown on the basis of the obtained results that the wave front from the local instantaneous source moves in radial directions with acceleration. The obtained results are important for explanation of observed properties of wave perturbations near the solar atmosphere transition region, whose appearance correlates with coronas mass injection.
Analytically and numerically calculations according to the original effective algorithms for largescale acoustic-gravity wave perturbations in the chromosphere from sources at the level of the photosphere are analyzed. Limitations to the energy flux of acoustic-gravity waves from the photosphere through the chromosphere are formulated. Structure of a narrow region with elevated pressure at the resonance altitude where the horizontal phase wave velocity is equal to the sound velocity is examined.
This article is about staff issues in NKVD's filtration camps, sources of staff recruting. It is revealed that these camps were ruled by a bunch of a different organization, that made a lot of problems in a filtration work.
A method based on the spectral analysis of thermowave oscillations formed under the effect of radiation of lasers operated in a periodic pulsed mode is developed for investigating the state of the interface of multilayered systems. The method is based on high sensitivity of the shape of the oscillating component of the pyrometric signal to adhesion characteristics of the phase interface. The shape of the signal is quantitatively estimated using the correlation coefficient (for a film–interface system) and the transfer function (for multilayered specimens).