EFFECTS OF PHYSICAL STRESS ON VISUAL ACUITY IN THE PLAIN AND MOUNTAIN CONDITIONS

2021 ◽  
Author(s):  
Светлана Васильевна Морякина ◽  
Хадижат Адамовна Гагаева ◽  
Тамила Исаевна Матиева
Keyword(s):  
Visual Acuity ◽  
Phase Change ◽  
Physical Stress ◽  
Gradual Decrease ◽  
Hypoxic Hypoxia ◽  
Scientific Article ◽  
Full Time ◽  
Two Phase ◽  
Visual Functions

Научная статья посвящена установлению изменений со стороны зрительных функций у студенток старших курсов очно-заочной формы обучения в условиях гипоксической и динамической гипоксии. В период акклиматизации к гипоксической гипоксии в течение пятнадцати дней наблюдалась волнообразность или двухфазность изменения остроты зрения. Повышение с первого по пятый день и постепенное снижение с десятого по пятнадцатый день. Scientific article is devoted to establishing changes on the part of visual functions in students of senior courses of full-time education in conditions of hypoxic and dynamic hypoxia. During the period of acclimatization to hypoxic hypoxia, waviness or two-phase change in visual acuity was observed for fifteen days. Increase from day one to day five and gradual decrease from day ten to day fifteen.

scholarly journals Numerical Study of a Cooling System Using Phase Change of a Refrigerant in a Thermosyphon

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3634
Author(s):  
Grzegorz Czerwiński ◽  
Jerzy Wołoszyn
Keyword(s):  
Mass Transfer ◽  
Phase Change ◽  
Heat Dissipation ◽  
Cooling System ◽  
Numerical Study ◽  
Relaxation Parameter ◽  
Phase Changes ◽  
Transfer Time ◽  
Two Phase ◽  
Time Relaxation

With the increasing trend toward the miniaturization of electronic devices, the issue of heat dissipation becomes essential. The use of phase changes in a two-phase closed thermosyphon (TPCT) enables a significant reduction in the heat generated even at high temperatures. In this paper, we propose a modification of the evaporation–condensation model implemented in ANSYS Fluent. The modification was to manipulate the value of the mass transfer time relaxation parameter for evaporation and condensation. The developed model in the form of a UDF script allowed the introduction of additional source equations, and the obtained solution is compared with the results available in the literature. The variable value of the mass transfer time relaxation parameter during condensation rc depending on the density of the liquid and vapour phase was taken into account in the calculations. However, compared to previous numerical studies, more accurate modelling of the phase change phenomenon of the medium in the thermosyphon was possible by adopting a mass transfer time relaxation parameter during evaporation re = 1. The assumption of ten-fold higher values resulted in overestimated temperature values in all sections of the thermosyphon. Hence, the coefficient re should be selected individually depending on the case under study. A too large value may cause difficulties in obtaining the convergence of solutions, which, in the case of numerical grids with many elements (especially three-dimensional), significantly increases the computation time.

Shock–like structure of phase-change flow in porous media

1981 ◽  
Vol 104 ◽  
pp. 467-482 ◽  
Author(s):  
L. A. Romero ◽  
R. H. Nilson
Keyword(s):  
Porous Media ◽  
Phase Change ◽  
Single Phase ◽  
Flow In Porous Media ◽  
Two Phase ◽  
Flows In Porous Media ◽  
Dissipative Effects ◽  
Condensing Flows ◽  
Self Similar ◽  
Phase Change Flows

Shock-like features of phase-change flows in porous media are explained, based on the generalized Darcy model. The flow field consists of two-phase zones of parabolic/hyperbolic type as well as adjacent or imbedded single-phase zones of either parabolic (superheated, compressible vapour) or elliptic (subcooled, incompressible liquid) type. Within the two-phase zones or at the two-phase/single-phase interfaces, there may be steep gradients in saturation and temperature approaching shock-like behaviour when the dissipative effects of capillarity and heat-conduction are negligible. Illustrative of these shocked, multizone flow-structures are the transient condensing flows in porous media, for which a self-similar, shock-preserving (Rankine–Hugoniot) analysis is presented.

Modeling of a two-phase system with phase change, applications in planetology: Earth's inner core and Transneptunian objects

2021 ◽  
Author(s):  
Robin Métayer ◽  
Renaud Deguen ◽  
Aurélie Guilbert-Lepoutre ◽  
Marine Lasbleis ◽  
Jenny Wong
Keyword(s):  
Phase Change ◽  
Inner Core ◽  
Phase System ◽  
Two Phase ◽  
Transneptunian Objects ◽  
Earth’S Inner Core

scholarly journals Two-phase change in CO2, Antarctic temperature and global climate during Termination II

2013 ◽  
Vol 6 (12) ◽  
pp. 1062-1065 ◽  
Author(s):  
A. Landais ◽  
G. Dreyfus ◽  
E. Capron ◽  
J. Jouzel ◽  
V. Masson-Delmotte ◽  
...  
Keyword(s):  
Phase Change ◽  
Global Climate ◽  
Two Phase

scholarly journals Visual Functions in Children in Remote Postoperative Period after Laser Treatment of Threshold Stages of Retinopathy of Prematurity

2018 ◽  
Vol 15 (2S) ◽  
pp. 18-23
Author(s):  
M. V. Pshenichnov ◽  
O. V. Kolenko ◽  
V. V. Egorov ◽  
E. L. Sorokin
Keyword(s):  
Visual Acuity ◽  
Postoperative Period ◽  
Retinopathy Of Prematurity ◽  
Vision Loss ◽  
State Institution ◽  
Laser Coagulation ◽  
Visual Functions ◽  
Functional Changes ◽  
Continuous Sampling ◽  
High Degree

Purpose.Analysis of visual functions in children in remote postoperative period after laser coagulation (LC) of threshold stages of retinopathy of prematurity (ROP).Patients and methods. In 2017, we selected and investigated 18 children, who previously had an LC of threshold stages of ROP in 2008–2009 in the Khabarovsk branch of the S.N. Fyodorov State Institution Eye Microsurgery Complex (continuous sampling method). There were 5 boys and 13 girls aged from 8 to 9 years at the time of LC. Anterior and posterior eye segments of the eyes (biomicroscopy, ophthalmoscopy), visual acuity, clinical refraction, concomitant pathology were evaluated.Results. We have revealed that regressive ROP after LC is characterized by the presence of serious anatomical and functional changes in the eyes. First, these are refractive disorders, which revealed in 90.5% of cases. Most often revealed: myopic refraction — 61% of all cases, of which more than half (53%) is its high degree; or its combination with compound myopic astigmatism (77% eyes); anisometropia was detected in 39% children. These refractive disorders led to the development of strabismus (61% children) and mixed amblyopia (60%). Despite the combined ophthalmologic pathology, 17% children developed visual functions with achievement of binocular vision, in most children visual functions still continue to develop, although they are not high due to amblyopia. High visual acuity (from 0.8 and above) in both eyes was formed in 22% children; visual acuity in the range of 0.5–0.7 in both eyes was formed in 17% children. Unfortunately, 44.5% children at the time of examination had low visual functions (in the range of 0.05–0.4) in both eyes. Extremely low visual acuity (from 0.01 to 0.04) in both eyes was identified in 11% children; absolute blindness in one of the eyes was in 11% children.Conclusions. LC is reliable way to prevent vision loss from retinal detachment in children with threshold stages of ROP. 

scholarly journals HYDRODYNAMIC FEATURES OF SUSPENSIONS AND EMULSIONS FLOWS.

2021 ◽  
Vol 2 (446) ◽  
pp. 99-104
Author(s):  
S.R. Rasulov ◽  
G.R. Mustafayeva
Keyword(s):  
Gas Flow ◽  
Fine Particles ◽  
Mutual Influence ◽  
Transport Coefficients ◽  
Spherical Particles ◽  
Scientific Article ◽  
Two Phase ◽  
Real Picture ◽  
Turbulent Gas Flow ◽  
Gas Pulsations

This scientific article is devoted to the problems associated with the flow of suspensions and emulsions and some simplifications of the real picture of the flow of a polydisperse medium are made. It is also stipulated that differential equations characterizing the motion of suspensions and emulsions should take into account the fundamental discontinuity of the medium and the physicochemical processes of heat and mass transfer occurring in it. Taking into account all these factors, a general equation for multiphase systems is proposed with certain simplifications that do not change. The behavior of particles in two-phase systems, their concentration, collision and coagulation are considered. As a result, it was concluded that there is a multifactorial interaction and mutual influence of both phases in a dispersed flow. A differential equation of motion of a single i-th spherical particle in suspension was proposed, and an equation describing the drag force of a solid spherical particles. Equations of conservation of mass and momentum are presented for one-dimensional laminar motion of two incompressible phases in a gravity field with the same pressure in the phases. Having studied the parameters of the flow of fine particles in a turbulent gas flow, some assumptions were made. It was found that the pulsating motion of particles, performed by them during one period of gas pulsations, can be represented as a change in the pulsating gas velocity in time. The parameter of entrainment of particles by a pulsating medium is an important characteristic in determining the transport coefficients in a turbulent flow. It is concluded that the presence of various kinds of particles in the liquid complicates the problem of solving hydromechanical problems in turbulent and laminar flow, and the assumptions given in the work facilitate the study of this problem.

Binary two-phase flow with phase change in porous media

2001 ◽  
Vol 27 (3) ◽  
pp. 477-526 ◽  
Author(s):  
S. Békri ◽  
O. Vizika ◽  
J.-F. Thovert ◽  
P.M. Adler
Keyword(s):  
Porous Media ◽  
Phase Change ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase
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