278 research outputs found
Thin films flowing down inverted substrates: Three dimensional flow
We study contact line induced instabilities for a thin film of fluid under
destabilizing gravitational force in three dimensional setting. In the previous
work (Phys. Fluids, {\bf 22}, 052105 (2010)), we considered two dimensional
flow, finding formation of surface waves whose properties within the
implemented long wave model depend on a single parameter,
, where is the capillary number and is
the inclination angle. In the present work we consider fully 3D setting and
discuss the influence of the additional dimension on stability properties of
the flow. In particular, we concentrate on the coupling between the surface
instability and the transverse (fingering) instabilities of the film front. We
furthermore consider these instabilities in the setting where fluid viscosity
varies in the transverse direction. It is found that the flow pattern strongly
depends on the inclination angle and the viscosity gradient
The Modified Weighted Slab Technique: Models and Results
In an attempt to understand the source and propagation of galactic cosmic
rays we have employed the Modified Weighted Slab technique along with recent
values of the relevant cross sections to compute primary to secondary ratios
including B/C and Sub-Fe/Fe for different galactic propagation models. The
models that we have considered are the disk-halo diffusion model, the dynamical
halo wind model, the turbulent diffusion model and a model with minimal
reacceleration. The modified weighted slab technique will be briefly discussed
and a more detailed description of the models will be given. We will also
discuss the impact that the various models have on the problem of anisotropy at
high energy and discuss what properties of a particular model bear on this
issue.Comment: LaTeX - AASTEX format, Submitted to ApJ, 8 figures, 20 page
Three-dimensional localized coherent structures of surface turbulence. III Experiment and model validation
The paper continues a series of publications devoted to the 3D nonlinear
localized coherent structures on the surface of vertically falling liquid
films. The work is primarily focussed on experimental investigations. We study:
(i) instabilities and transitions leading to 3D coherent structures; (ii)
characteristics of these structures. Some nonstationary effects are also
studied numerically. Our experimental results, as well as the results of other
investigators, are in a good agreement with our theoretical and numerical
predictions.Comment: 42 pages, 15 figure
Evolution of the cosmic ray anisotropy above 10^{14} eV
The amplitude and phase of the cosmic ray anisotropy are well established
experimentally between 10^{11} eV and 10^{14} eV. The study of their evolution
into the energy region 10^{14}-10^{16} eV can provide a significant tool for
the understanding of the steepening ("knee") of the primary spectrum. In this
letter we extend the EAS-TOP measurement performed at E_0 around 10^{14} eV, to
higher energies by using the full data set (8 years of data taking). Results
derived at about 10^{14} and 4x10^{14} eV are compared and discussed. Hints of
increasing amplitude and change of phase above 10^{14} eV are reported. The
significance of the observation for the understanding of cosmic ray propagation
is discussed.Comment: 4 pages, 3 figures, accepted for publication on ApJ Letter
Investigation into the operation of an autothermal two-section subbituminous coal fluidized bed gasifier
Using a newly developed experimental setup, the features and advantages of an autothermal single-casing atmospheric subbituminous coal fluidized bed air-blown gasifier, combining a combustion and gasification section, and mixing the dispersed phase (inert material, char) and heat exchange between them through an annular transfer device, have been revealed. To increase the efficiency of the gasifier, an experimental-computational method was developed find the conditions for optimal operation, combining changing the annular flow’s geometry and regulating the primary air for gasification. A simple and reliable multizone thermodynamic calculation model makes it possible to predict the composition of char and syngas in the gasification section with acceptable accuracy. This method confirmed that a two-section fluidized bed gasifier can provide efficient gasification of solid fuels and is suitable for use in small-scale cogeneration plants. Syngas with a heating value of 3.6–4.5 MJ/m3 and CGE of 38.2%–42.3% was obtained in the experimental setup without optimizing the primary air flow rate. With optimization, the indicators increased to the heating value of syngas of 5.20–5.34 MJ/m3 and CGE of 42.5%–50.0%. With heat regeneration of 0.8, CGE increases to 70%. © 2023, The Author(s).Ministry of Education and Science of the Russian Federation, MinobrnaukaThe research funding from the Ministry of Science and Higher Education of the Russian Federation (Ural Federal University Program of Development within the Priority-2030 Program) is gratefully acknowledged
Dynamics of Vortex Pair in Radial Flow
The problem of vortex pair motion in two-dimensional plane radial flow is
solved. Under certain conditions for flow parameters, the vortex pair can
reverse its motion within a bounded region. The vortex-pair translational
velocity decreases or increases after passing through the source/sink region,
depending on whether the flow is diverging or converging, respectively. The
rotational motion of two corotating vortexes in a quiescent environment
transforms into motion along a logarithmic spiral in the presence of radial
flow. The problem may have applications in astrophysics and geophysics.Comment: 13 pages, 9 figure
The East-West method: an exposure-independent method to search for large scale anisotropies of cosmic rays
The measurement of large scale anisotropies in cosmic ray arrival directions
at energies above 10^13 eV is performed through the detection of Extensive Air
Showers produced by cosmic ray interactions in the atmosphere. The observed
anisotropies are small, so accurate measurements require small statistical
uncertainties, i.e. large datasets. These can be obtained by employing ground
detector arrays with large extensions (from 10^4 to 10^9 m^2) and long
operation time (up to 20 years). The control of such arrays is challenging and
spurious variations in the counting rate due to instrumental effects (e.g. data
taking interruptions or changes in the acceptance) and atmospheric effects
(e.g. air temperature and pressure effects on EAS development) are usually
present. These modulations must be corrected very precisely before performing
standard anisotropy analyses, i.e. harmonic analysis of the counting rate
versus local sidereal time. In this paper we discuss an alternative method to
measure large scale anisotropies, the "East-West method", originally proposed
by Nagashima in 1989. It is a differential method, as it is based on the
analysis of the difference of the counting rates in the East and West
directions. Besides explaining the principle, we present here its mathematical
derivation, showing that the method is largely independent of experimental
effects, that is, it does not require corrections for acceptance and/or for
atmospheric effects. We explain the use of the method to derive the amplitude
and phase of the anisotropy and we demonstrate its power under different
conditions of detector operation
The fate of the scientist as a reflection of the epoch: in memory of the first rector of the Kuban State Medical University Nikolai F. Melnikov-Razvedenkov
The paper analyzes the life and professional journey of Nikolai F. Melnikov-Razvedenkov, an outstanding scientist, doctor, and professor, as a reflection of Russian history from the end of the 19th century till the first quarter of the 20th century. The study identifies the role of Nikolai F. Melnikov-Razvedenkov in the development of medical science and the establishment of medical education in the Kuban region. The analysis was conducted with the involvement of archival records, personal correspondence, and scientific works of Nikolai F. Melnikov-Razvedenkov. To solve research problems, the authors used historical descriptive, comparative historical, problem-based chronological, biographical methods, and the method of monographic description. It is shown that the scientist’s fate mirrors the cultural and historical era experienced by the country. The authors define the exclusive role of Nikolai F. Melnikov-Razvedenkov in the establishment of the Kuban Medical Institute. His life path helped reveal the inviolability of medical ethics based on mercy, dedication to the profession, and willingness to serve people. Even in the situation of social upheaval Nikolai F. Melnikov-Razvedenkov found the meaning of his life in scientific work and helping people. His example will allow the modern generation of doctors to gain a greater understanding of the essential purpose of their work
Patient routing and process approach implementation for regional oncology service
Background. Cancer care involves a multidisciplinary approach to diagnosis and treatment of patients. A complex interaction of actors in the deployment of oncology services dictates usage of modern management technologies for improving the quality and efficiency of patient care through processes optimisation.Objectives. Provision of recommendations for patient routing based on research into the oncology service inter-level information exchange, integration of the process approach and electronic services. The lack of a unified information space with a regional oncology service has been explained. Measures are proposed for the patient routing optimisation as part of establishing a unified digital oncology service circuit.Methods. The oncology service was effectively remodelled through functional and information engineering of electronic services and the process management integration to establish a horizontal decision flow between facilities and employees on a process level bypassing the supervisor coordination. Statistical approaches were used to analyse the oncological patient population.Results. The following electronic services have been implemented: specialised patient referral routing, telemedicine and teleradiology. A comprehensive information framework has been created comprising medical, laboratory and radiological information subsystems integrated through regional electronic services of the unified state healthcare information platform. The goals, objectives, general principles, architecture and expected social economic impact on healthcare of Krasnodar Krai have been defined.Conclusion. Use of electronic services ensures an improved quality of specialised care and effective routing of patients. We perceive prospects of the integrated information platform in the extension and improvement of its subsystems’ functionality and content, sourcing more data providers and the circuit expansion to the federal and regional levels
A Dipole Vortex Model of Obscuring Tori in Active Galaxy Nuclei
The torus concept as an essential structural component of active galactic
nuclei (AGN) is generally accepted. Here, the situation is discussed when the
torus "twisting" by the radiation or wind transforms it into a dipole toroidal
vortex which in turn can be a source of matter replenishing the accretion disk.
Thus emerging instability which can be responsible for quasar radiation flares
accompanied by matter outbursts is also discussed. The "Matreshka" scheme for
an obscuring vortex torus structure capable of explaining the AGN variability
and evolution is proposed. The model parameters estimated numerically for the
luminosity close to the Eddington limit agree well with the observations.Comment: 17 pages, 11 figures, version of this paper is published in Astronomy
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