186 research outputs found

    Determinants of households’ credit behavior in Russia

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    Purpose: The main goal of this work is to substantiate the need to consider microeconomic statistics when analyzing consumer lending to the population, as well as implementing approaches to modeling household credit behavior at the micro level. Design/Methodology/Approach: The article proposes and implements a comprehensive statistical approach that allows identifying the specificity of the influence of demographic, socio-economic characteristics of households on their credit activity. Findings: The article states that loan borrowings are more often found in households with children of preschool age who are in relatively high-income groups, who much more often inform about cash incomes that do not correspond to the declared level of consumption. Members of these households are more likely to work. The age range of borrowers expanded during the study period, and no prevalence of any age group was observed. Practical Implications: This result is of great practical importance, since, as already indicated, in assessing the solvency of the borrower, credit organizations are mainly focused on individual characteristics. Originality/value: It was found that the hypothesis that individual characteristics are important determinants of household lending activity has not been confirmed. And variables that characterize households significantly affect their credit behavior.peer-reviewe

    Effect of forced convection on dendrite growth kinetics

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    In this work, using currently developing model of convective transport and dendrite growth, results on theoretical modeling are presented. A stable relation for the dendrite tip velocity V and its tip diameter ρ via the selection theory and undercooling balance ΔT is discussed. It is shown that convective transport plays essential role in quantitative description of dendrite growth kinetics. © 2019 Author(s)

    Effect of forced convection on dendrite growth kinetics

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    In this work, using currently developing model of convective transport and dendrite growth, results on theoretical modeling are presented. A stable relation for the dendrite tip velocity V and its tip diameter r via the selection theory and undercooling balance is discussed. It is shown that convective transport plays essential role in quantitative description of dendrite growth kinetics.Toropova L. V. acknowledges the support from the Ministry of Education and Science of the Russian Federation [grant number 1.12804.2018/12.2]

    THE SHAPE OF DENDRITIC TIPS

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    This thesis is devoted to the study of the tip shape of dendritic crystals grown from a supercooled liquid. It is shown that the recently found shape function describes the tip region of dendritic crystals (at the crystal vertex and some distance from it) well.L.V.T gratefully acknowledges research funding from the DAAD (Personal ref. no.: 91687480) and the Ministry of Science and Higher Education of the Russian Federation (project passport No. 2338-21) within the "Michael Lomonosov" programme scheme

    Thermo-solutal and kinetic modes of stable dendritic growth with different symmetries of crystalline anisotropy in the presence of convection

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    Motivated by important applications in materials science and geophysics, we consider the steady-state growth of anisotropic needle-like dendrites in undercooled binary mixtures with a forced convective flow. We analyse the stable mode of dendritic evolution in the case of small anisotropies of growth kinetics and surface energy for arbitrary Péclet numbers and n-fold symmetry of dendritic crystals. On the basis of solvability and stability theories, we formulate a selection criterion giving a stable combination between dendrite tip diameter and tip velocity. A set of nonlinear equations consisting of the solvability criterion and undercooling balance is solved analytically for the tip velocity V and tip diameter ? of dendrites with n-fold symmetry in the absence of convective flow. The case of convective heat and mass transfer mechanisms in a binary mixture occurring as a result of intensive flows in the liquid phase is detailed. A selection criterion that describes such solidification conditions is derived. The theory under consideration comprises previously considered theoretical approaches and results as limiting cases. This article is part of the theme issue ‘From atomistic interfaces to dendritic patterns’. © 2018 The Author(s) Published by the Royal Society. All rights reserved.Russian Science Foundation, RSF: 16-11-1009550WM1541Data accessibility. This article has no additional data. Authors’ contributions. All authors contributed equally to the present review paper. Competing interests. The authors declare that they have no competing interests. Funding. This work was supported by the Russian Science Foundation (grant number 16-11-10095) and the German Space Center Space Management (under contract number 50WM1541)

    Dynamical law of the phase interface motion in the presence of crystals nucleation

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    In this paper, we develop a theory of solid/liquid phase interface motion into an undercooled melt in the presence of nucleation and growth of crystals. A set of integrodifferential kinetic, heat and mass transfer equations is analytically solved in the two-phase and liquid layers divided by the moving phase transition interface. To do this, we have used the saddle-point method to evaluate a Laplace-type integral and the small parameter method to find the law of phase interface motion. The main result is that the phase interface Z propagates into an undercooled melt with time t as Z(t)=σt+εχt7/2 with allowance for crystal nucleation. The effect of nucleation is in the second contribution, which is proportional to t7 / 2 whereas the first term ∼t represents the well-known self-similar solution. The nucleation and crystal growth processes are responsible for the emission of latent crystallization heat, which reduces the melt undercooling and constricts the two-phase layer thickness (parameter χ< 0). © 2022, The Author(s).Russian Science Foundation, RSF: 21-79-10012Authors gratefully acknowledge financial support from the Russian Science Foundation (project no. 21-79-10012)

    Control optimization for asynchronized switched motor of mine hoist plant using Bellman – Lyapunov method

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    У статті розглядається задача синтезу нелінійного регулятора швидкості асинхронізованого вентильного двигуна. Для знаходження оптимального закону управління, використаний метод Беллмана - Ляпунова з використанням концепції методу «занурення». Здійснено моделювання та зроблений порівняльний аналіз електропривода зі стандартним ПІ - регулятором, а також з синтезованим оптимальним регулятором.The problem of synthesis of nonlinear speed controller asynchronized switched motor is considered. To find the optimal control law by, the method of Bellman - Lyapunov by concept of "immersion" is used. Modeling and comparative analysis of the system with the standard PI - controller, as well as the synthesized regulators are made.В статье рассматривается задача синтеза нелинейного регулятора скорости асинхронизированного вентильного двигателя. Для нахождения оптимального закона управления, использован метод Беллмана - Ляпунова с использованием концепции метода «погружения». Осуществлено моделирование и произведен сравнительный анализ электропривода со стандартным ПИ - регулятором, а также с синтезированным оптимальным регулятором

    Implementation of PLC-based optimal control system of rotor wheel motors with the concept of Pearson method

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    Розглянуто можливість реалізації оптимального керування електродвигуном роторного колеса при використанні програмованих логічних контролерів. Вибрано функціонал якості, при якому забезпечується висока якість регулювання швидкості і суттєво спрощується процедура аналітичного конструювання. Синтезовано закон оптимального керування методом динамічного програмування з використанням концепції методу Пірсона. Зроблено аналіз виконання теореми Котельникова - Шеннона при використанні програмованого логічного контролера і реалізації в ньому отриманого закону управління.The possibility of implementing the optimal control by rotor wheel motors using programmable logic controllers is considered. Functional of quality, which ensures high quality control and a greatly simplified procedure for analytical design, is selected. Optimal control law by dynamic programming method using the concept of Pearson is synthesized. The analysis of the implementation of the Kotelnikov-Shennon theorem by using a programmable logic controller and realization of obtained control law is produced.Рассмотрена возможность реализации оптимального управления электродвигателем роторного колеса при использовании программируемых логических контроллеров. Выбран функционал качества, при котором обеспечивается высокое качество регулирования скорости и существенно упрощается процедура аналитического конструирования. Синтезирован закон оптимального управления методом динамического программирования с использованием концепции метода Пирсона. Произведен анализ выполнения теоремы Котельникова - Шеннона при использовании программируемого логического контроллера и реализации в нем полученного закона управления

    Oxidation of hydroxylamine as an indicator reaction for the kinetic determination of copper and iron

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    The oxidation of hydroxylamine by hexacyanoferrate(III) is proposed as an indicator reaction for kinetic determining copper(II) traces (detection limit of 2 × 10-8 M). It is shown that iron(II) and total iron can be determined with a detection limit of 2 × 10-6 M using the oxidation of hydroxylamine by potassium bromate, catalyzed by Fe(II). The bromination of Methyl Orange catalyzed by bromide formed in the reduction of the bromate ion is proposed as an indicator reaction. © 1999 MAEe Cyrillic signK "Hayκa/Interperiodica"

    Photometric determination of thiourea with the use of sodium nitroprusside

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    Conditions for the formation of the colored compound in the reaction of thiourea with sodium nitroprusside and the products of its transformations were studied. A procedure for the photometric determination of thiourea was developed. The procedure is based on the complexation of thiourea with pentacyanoferrate(II) ion, which can be obtained by the basic hydrolysis of sodium nitroprusside at pH ≥ 12, followed by acidification of the solution to pH 6. When the reagent is present in excess, the absorbance of the solution of the complex at 590 nm is linearly proportional to the thiourea concentration in the solution within the range 4 × 10-6-1 × 10-4 M. © 1997 MAEe Cyrillic signK Hayκa/Interperiodica Publishing
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