scholarly journals Рост перегревных неустойчивостей в метастабильном металле

2018 ◽  
Vol 44 (20) ◽  
pp. 62
Author(s):  
В.И. Орешкин
Keyword(s):  
Comparative Analysis ◽  
Phase State ◽  
Electric Explosion ◽  
Metastable Liquid ◽  
Two Phase ◽  
Small Perturbations ◽  
Unstable Phase ◽  
Initial Stage ◽  
Conducting Wire ◽  
Liquid Vapor

AbstractThe development of thermal (overheat) instabilities during the electric explosion of a conducting wire has been analyzed using the theory of small perturbations. At the initial stage of electric explosion (upon melting of the metal), the substance can occur in three phases: liquid, two-phase state (liquid + vapor), and metastable metal liquid (overheated liquid). Comparative analysis of the growth of overheat instabilities is performed as dependent on the phase in which the metal can occur. It is shown that, from the standpoint of development of overheat instability, the most unstable phase is the overheated metastable liquid.

scholarly journals Structure of tantalum coatings on NiTi substrate deposited by magnetron sputtering

2022 ◽  
Vol 2155 (1) ◽  
pp. 012013
Author(s):  
A S Dikov ◽  
A S Larionov ◽  
E A Zhakanbayev ◽  
L A Dikova ◽  
A Zh Sanssyzbayeva ◽  
...  
Keyword(s):  
Shape Memory ◽  
Phase State ◽  
Structural Phase ◽  
Interplanar Distance ◽  
X Ray Diffraction ◽  
Two Phase ◽  
Structural Phase State ◽  
Initial Stage ◽  
Coating Formation ◽  
Tantalum Coatings

Abstract The paper provides the results of studies of the structural-phase state of tantalum coatings prepared by magnetron deposition. The coatings were deposited on substrates made of titanium nickelide with a shape memory. The NiTi temperature during coating deposition did not exceed 100 °C. The structural-phase state of Ta was determined by X-ray diffraction at different stages of coating formation. It has been shown that at the initial stage of deposition, two-phase coatings (α- and β-Ta) are formed. The synthesis of the coating from Ta leads to the growth of interplanar distance of the B2 austenite phase in the crystallographic direction (100). The growth of interplanar spacing is caused by formation of microstresses during interaction with incident tantalum ions. The lattice parameters of the B19 ‘phase, responsible for appearance of the shape memory effect, do not change during deposition of the tantalum coating.

COGNITIVIZATION — THE NEXT STAGE OF INFORMATIZATION OF EDUCATION

2018 ◽  
pp. 5-11
Author(s):  
A. S. Christochevskaya ◽  
S. A. Christochevsky
Keyword(s):  
Comparative Analysis ◽  
Learning Resources ◽  
Technical Base ◽  
Initial Stage ◽  
New Knowledge ◽  
Good Material ◽  
E Learning ◽  
New Material ◽  
High Level ◽  
Paper Method

Informatization of education has been going on for 30 years. During this time, a good material and technical base appeared in schools, there are repositories of e-learning resources to which teachers have access. However, it is difficult to use these e-learning resources due to their too large number and not always high level. It is advisable to introduce a system of reviews and recommendations, to conduct a comparative analysis, as well as to make reviews of resources on a particular subject/topic. In addition, the demand for e-learning resources is affected by the fact that education authorities encourage not so much the use of e-learning resources as their development by the teacher himself. In general, the load on teachers has increased instead of the promised saving of time and effort when using the e-learning resources. At the same time, many e-learning resources are not very effective, since they do not meet the requirements of cognitiveness (they contribute not to learning, but to simple memorization of the material). It is necessary to explore the process of learning new material: this will allow you to create cognitive e-learning resources and other resources that would help you with equal probability to successfully acquire new knowledge for students belonging to different psycho-types. At the initial stage of the study of any subject, it is more expedient to use the usual “paper” method, that is, a textbook and not overload the student’s brain with excessive information. Only when he has mastered the basic provisions, we can turn to e-learning resources, bearing in mind that they must be cognitive, that is, they are aimed at logical perception and rapid intuitive learning, only in this case e-learning resources can be considered effective. The conclusion is formulated that cognitiveness is the next stage of informatization of education after the stage of electronization.

Investigation of two-dimensional nonstationary processes of outflow a gas-saturated liquid from axisymmetric vessels

2012 ◽  
Vol 9 (1) ◽  
pp. 47-52
Author(s):  
R.Kh. Bolotnova ◽  
V.A. Buzina
Keyword(s):  
Comparative Analysis ◽  
Numerical Model ◽  
Liquid Mixture ◽  
Phase Model ◽  
Test Problems ◽  
Two Dimensional ◽  
Nonstationary Processes ◽  
Saturated Liquid ◽  
Two Phase ◽  
One Dimensional

The two-dimensional and two-phase model of the gas-liquid mixture is constructed. The validity of numerical model realization is justified by using a comparative analysis of test problems solution with one-dimensional calculations. The regularities of gas-saturated liquid outflow from axisymmetric vessels for different geometries are established.

Equation Describing the Equilibrium Two-Phase State of Substances

2019 ◽  
Vol 57 (5) ◽  
pp. 655-658
Author(s):  
A. I. Vitvitskiy
Keyword(s):  
Phase State ◽  
Two Phase

scholarly journals An experimental and theoretical investigation of diffusion in a two-phase alloy

1948 ◽  
Vol 192 (1031) ◽  
pp. 575-592 ◽  
Keyword(s):  
Free Energy ◽  
Single Phase ◽  
Phase State ◽  
Theoretical Treatment ◽  
Research Association ◽  
Essential Difference ◽  
Two Phase ◽  
Two Factors ◽  
Order Of Magnitude ◽  
The Difference

The present paper describes an investigation of diffusion in the solid state. Previous experimental work has been confined to the case in which the free energy of a mixture is a minimum for the single-phase state, and diffusion decreases local differences of concentration. This may be called ‘diffusion downhill’. However, it is possible for the free energy to be a minimum for the two-phase state; diffusion may then increase differences of concentration; and so may be called ‘diffusion uphill’. Becker (1937) has proposed a simple theoretical treatment of these two types of diffusion in a binary alloy. The present paper describes an experimental test of this theory, using the unusual properties of the alloy Cu 4 FeNi 3 . This alloy is single phase above 800° C and two-phase at lower temperatures, both the phases being face-centred cubic; the essential difference between the two phases is their content of copper. On dissociating from one phase into two the alloy develops a series of intermediate structures showing striking X-ray patterns which are very sensitive to changes of structure. It was found possible to utilize these results for a quantitative study of diffusion ‘uphill’ and ‘downhill’ in the alloy. The experimental results, which can be expressed very simply, are in fair agreement with conclusions drawn from Becker’s theory. It was found that Fick’s equation, dc / dt = D d2c / dx2 , can, within the limits of error, be applied in all cases, with the modification that c denotes the difference of the measured copper concentration from its equilibrium value. The theory postulates that D is the product of two factors, of which one is D 0f the coefficient of diffusion that would be measured if the alloy were an ideal solid solution. The theory is able to calculate D/D 0 , if only in first approximation, and the experiments confirm this calculation. It was found that in most cases the speed of diffusion—‘uphill’ or ‘downhill’—has the order of magnitude of D 0 . * Now with British Electrical Research Association.

scholarly journals Thermodynamics and Machine Learning Based Approaches for Vapor–Liquid–Liquid Phase Equilibria in n-Octane/Water, as a Naphtha–Water Surrogate in Water Blends

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 413
Author(s):  
Sandra Lopez-Zamora ◽  
Jeonghoon Kong ◽  
Salvador Escobedo ◽  
Hugo de Lasa
Keyword(s):  
Machine Learning ◽  
Liquid Phase ◽  
Phase Equilibria ◽  
Aspen Plus ◽  
Phase Region ◽  
Two Phase ◽  
Technical Literature ◽  
Phase Liquid ◽  
Liquid Vapor ◽  
Vapor Liquid

The prediction of phase equilibria for hydrocarbon/water blends in separators, is a subject of considerable importance for chemical processes. Despite its relevance, there are still pending questions. Among them, is the prediction of the correct number of phases. While a stability analysis using the Gibbs Free Energy of mixing and the NRTL model, provide a good understanding with calculation issues, when using HYSYS V9 and Aspen Plus V9 software, this shows that significant phase equilibrium uncertainties still exist. To clarify these matters, n-octane and water blends, are good surrogates of naphtha/water mixtures. Runs were developed in a CREC vapor–liquid (VL_ Cell operated with octane–water mixtures under dynamic conditions and used to establish the two-phase (liquid–vapor) and three phase (liquid–liquid–vapor) domains. Results obtained demonstrate that the two phase region (full solubility in the liquid phase) of n-octane in water at 100 °C is in the 10-4 mol fraction range, and it is larger than the 10-5 mol fraction predicted by Aspen Plus and the 10-7 mol fraction reported in the technical literature. Furthermore, and to provide an effective and accurate method for predicting the number of phases, a machine learning (ML) technique was implemented and successfully demonstrated, in the present study.

Evaporation of Single Drops of n-Pentane/n-Hexane Mixtures in Water

1992 ◽  
Vol 114 (4) ◽  
pp. 965-971 ◽  
Author(s):  
H. Shimaoka ◽  
Y. H. Mori
Keyword(s):  
Heat Transfer ◽  
Temperature Difference ◽  
Vapor Bubble ◽  
Experimental Results ◽  
Rise Velocity ◽  
Heat Transfer Characteristics ◽  
Two Phase ◽  
Transfer Characteristics ◽  
Preceding Work ◽  
Liquid Vapor

The evaporation of isolated drops (2.1−3.0 mm diameter) of nonazeotropic n-pentane/n-hexane mixtures in the medium of water was observed under pressures of 0.11−0.46 MPa and temperature differences up to 27 K. The mole fractions of n-pentane, x, in the mixtures were set at 0.9, 0.5, 0.1, and 0, to be completed by the condition x = 1 set in a preceding work (Shimaoka and Mori, 1990). Experimental results are presented in terms of the instantaneous rise velocity of, and an expression of instantaneous heat transfer to, each drop evaporating and thereby transforming into a liquid/vapor two-phase bubble and finally into a vapor bubble. The dependencies of the heat transfer characteristics on the pressure, the temperature difference, and x are discussed.

COMPARATIVE ANALYSIS OF ATTITUDES TOWARDS ENVIRONMENTAL ISSUES

2020 ◽  
Author(s):  
M.V. Yadrovskaya ◽  
◽  
N.A. Kalyuzhny
Keyword(s):  
Mathematical Modeling ◽  
Comparative Analysis ◽  
Statistical Modeling ◽  
Information Technologies ◽  
Environmental Issues ◽  
Internet Technologies ◽  
Rostov Region ◽  
Initial Stage ◽  
Don River ◽  
Graphical Presentation

The work was carried out within the framework of the initial stage of the master's research related to the application of mathematical modeling and information technologies to the study of environmental problems of water bodies. The work presents the results of statistical modeling associated with the processing of data from two surveys: residents of the Rostov region and foreign residents. Based on the results of surveys carried out using Internet technologies, the authors make some conclusions about the attitude of residents to the problems under consideration. The proposed results are accompanied by graphical presentation in the form of diagrams, which greatly simplifies understanding. The results also make it possible to justify the next stage of the scientific research - modeling plastic in the Don River.

On the phase state of thin silver wire cores during a fast electric explosion

2018 ◽  
Vol 25 (11) ◽  
pp. 112704 ◽  
Author(s):  
V. M. Romanova ◽  
G. V. Ivanenkov ◽  
A. R. Mingaleev ◽  
A. E. Ter-Oganesyan ◽  
I. N. Tilikin ◽  
...  
Keyword(s):  
Phase State ◽  
Silver Wire ◽  
Electric Explosion

Textures of the Hot-Forged Ti6Al4V Alloy

2013 ◽  
Vol 203-204 ◽  
pp. 111-114
Author(s):  
Adam Bunsch ◽  
Wiktoria Ratuszek ◽  
Małgorzata Witkowska ◽  
Joanna Kowalska ◽  
Aneta Łukaszek-Sołek
Keyword(s):  
Deformation Temperature ◽  
Phase State ◽  
Hexagonal Phase ◽  
Ti6al4v Alloy ◽  
The Body ◽  
Cubic Phase ◽  
Body Centered Cubic ◽  
Two Phase ◽  
Different Temperatures

This paper presents the results of the texture investigation in the hexagonal phase and the body-centered cubic  phase of the Ti6Al4V alloy hot-deformed by forging. Forging was performed at two different temperatures on the occurrence of the single  and in the two-phase  +  state. It was found that after deformation both  and  phases are textured and their textures strongly depends on deformation temperature.

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