Linear Regression Model of the Conveyor Type Transport System

This article discusses the prospects of using linear regression models to describe multi-section branched transport systems of conveyor type. A characteristic feature of the functioning of a multi-section transport system is the presence of resonant peak values for the flow parameters of the transport system and transport delay. Various variants of the linear regression model are investigated. It is shown that for multisection transport systems with a periodic nature of the magnitude of the incoming material flow into the transport system and periodic nature of the regulation of the belt speed the value of the transport delay is a quasi-stationary value. The transport delay can be excluded from model variables. Analysis of the various variants of linear regression models considered in the article shows that using them to describe branched transport systems is ineffective. The considered models can only be used for a qualitative analysis of the output stream from the transport system. The absence of a linear relationship between the input and output flow parameters of the transport system is shown

Orientation and Aggregation of Polymer Chains in the Straight Electrospinning Jet

The dynamics of a straight section of a jet arising during the electrospinning of a polymer solution without entanglements, and the orientation of polymer chains in the jet were explored based on the analysis of the forces balance equation and the rheological equation of the finitely extensible nonlinear elastic model. Two modes of the jet behavior were predicted. At relatively low volumetric flow rates, the straight jet has a limited length, after that, its rectilinear motion becomes impossible, while at higher flow rates, the jet always remains straightforward. It is shown that polymer chains in a jet can be strongly stretched, which leads to phase separation in a spinning solution. Aggregation of the stretched chains was also studied and the parameters of the emerging inhomogeneous structure were predicted

Дослідження впливу технологічних умов мікродугового оксидування магнієвих сплавів на їх структурний стан і механічні властивості

We examined the patterns in the formation of MAO-coatings on magnesium alloys. Low density and high specific strength of magnesium alloys is the basis for their widespread use. However, poor corrosion resistance of magnesium alloys limits the scope of their application. This problem is solved by transforming the surface layer of magnesium alloys into the multiphase coatings that consist of crystalline oxides and salts of magnesium. The most effective formulations of electrolytes were selected to ensure obtaining the MAO layers of good quality. We explored the phase composition of coatings, hardness, adhesion between coatings and the base, and their protective properties. It was found that the most effective are the multi-component electrolytes containing alkali NaOH, sodium aluminate NaAlO2 and sodium hexametaphosphate Na5P3O10. The MAO treatment provides strengthening of surface (hardness of coatings is 2000−6600 MPa) and improves protective properties. It is demonstrated that the highest protective properties are displayed by the MAO-coatings that contain in their composition, along with MgO, the MgAl2O4 spinel. Protective properties are improved with an increase in the spinel content. This is due to the fact that the occurrence of spinel in the composition of a coating, in contrast to MgO, is accompanied by the increase in specific volume of the coating, resulting in the occurrence of compressive stresses and, as a consequence, in the formation of thicker coatings. The recommendations are given regarding the changes in the composition of electrolyte and parameters of electrolysis to ensure an increase in spinel in the composition of the coating.Приведены исследования структуры и свойств покрытий, полученных при микродуговой обработке на магниевом сплаве. Обработка проводилась в анодно-катодном режиме в щелочном электролите с разными примесями. Показана возможность формирования кристаллических оксидных покрытий разного фазового состава (MgO, MgAl2O4, Mg2Sі4, Mg3(PO4)2), толщиной до 300 мкм, которые имеют высокую адгезию с основой, хорошие защитные свойства и высокую твердость, достигающую 6,6 ГПаНаведені дослідження структури і властивостей покриттів, отриманих при мікродуговій обробці на магнієвому сплаві. Обробка проводилася при анодно-катодному режимі в лужному електроліті з різними домішками. Показана можливість формування кристалічних оксидних покриттів різного фазового складу (MgO, MgAl2O4,Mg2SiO4, Mg3(PO4)2) товщиною до 300 мкм, що мають високу адгезію з основою, гарні захисні властивості і високу твердість, яка досягає 6,6 ГП

Политика США по созданию систем противоракетной обороны в балтийском и североевропейском регионах

This article examines the implications of the deployment of the US ballistic missile defense (BMD) system in the Baltic and Nordic regions. These implications are to be considered to ensure Russia’s military security. Using the structural-functional method, the authors analyse the internal structure of the US BMD in Europe, stages of its implementation, and its influence on the military equilibrium in the region. Being similar to other regional missile defence systems of the Pentagon, BMD in Europe increases the offensive capabilities of the US armed forces and its allies and in doing so, it stops performing a purely defensive mission declared by Washington. It is stressed that the deployment of mobile sea- and land-based BMD elements in the Baltic Sea region and Nordic countries will inevitably destabilize the strategic situation and may lead to a new round of arms race in the region. The efficacy of BMD in Europe is evaluated from the perspective of military technology. The system’s potential threats to Russia’s military security and its armed forces are assessed. The article considers measures to enhance national security that could be taken by Russia provided the US plans to deploy BMD in Europe are fully implemented

The US ballistic missile defence policy in the Baltic and Nordic regions

This article examines the implications of the deployment of the US ballistic missile defense (BMD) system in the Baltic and Nordic regions. These implications are to be considered to ensure Russia’s military security. Using the structural-functional method, the authors analyse the internal structure of the US BMD in Europe, stages of its implementation, and its influence on the military equilibrium in the region. Being similar to other regional missile defence systems of the Pentagon, BMD in Europe increases the offensive capabilities of the US armed forces and its allies and in doing so, it stops performing a purely defensive mission declared by Washington. It is stressed that the deployment of mobile sea- and land-based BMD elements in the Baltic Sea region and Nordic countries will inevitably destabilize the strategic situation and may lead to a new round of arms race in the region. The efficacy of BMD in Europe is evaluated from the perspective of military technology. The system’s potential threats to Russia’s military security and its armed forces are assessed. The article considers measures to enhance national security that could be taken by Russia provided the US plans to deploy BMD in Europe are fully implemented

The Elasticity of Polymer Melts and Solutions in Shear and Extension Flows

This review is devoted to understanding the role of elasticity in the main flow modes of polymeric viscoelastic liquids—shearing and extension. The flow through short capillaries is the central topic for discussing the input of elasticity to the effects, which are especially interesting for shear. An analysis of the experimental data made it possible to show that the energy losses in such flows are determined by the Deborah and Weissenberg numbers. These criteria are responsible for abnormally high entrance effects, as well as for mechanical losses in short capillaries. In addition, the Weissenberg number determines the threshold of the flow instability due to the liquid-to-solid transition. In extension, this criterion shows whether deformation takes place as flow or as elastic strain. However, the stability of a free jet in extension depends not only on the viscoelastic properties of a polymeric substance but also on the driving forces: gravity, surface tension, etc. An analysis of the influence of different force combinations on the shape of the stretched jet is presented. The concept of the role of elasticity in the deformation of polymeric liquids is crucial for any kind of polymer processing

Дослідження можливостей фазово-структурної інженерії покриттів на сплаві Д16 при мікродуговом оксидуванні в електролітах різних типів

The effect of electrolysis conditions with different electrolyte compositions on the growth kinetics, phase-structural state, and hardness of coatings obtained by microarc oxidation (MAO) on the D16 aluminum alloy (base – aluminum, main impurity Cu) was studied.An analysis of the results obtained showed that the choice of the type of electrolyte and the conditions for the MAO process makes it possible to vary the growth kinetics and phase-structural state of the coating on the D16 aluminum alloy within a wide range. For all types of electrolytes, with an increase in the content of KOH, Na2SiO3, or KOH+Na2SiO3, the growth rate of MAO coatings increases.It was found that in MAO coatings obtained in an alkaline (KOH) electrolyte, a two-phase (γ−Al2O3 and α−Al2O3 phases) crystalline state is formed. An increase in the KOH concentration leads to an increase in the relative content of the α–Al2O3 phase (corundum). During the formation in a silicate electrolyte, the phase composition of MAO coatings with an increase in the content of liquid glass (Na2SiO3) changes from a mixture of the γ−Al2O3 phase and mullite (3Al2O3∙2SіO2) to an X-ray amorphous phase. The use of a complex electrolyte leads to a two-phase state of the coating with a large (compared to an alkaline electrolyte) shift of the γ−Al2O3→α−Al2O3 transformation towards the formation of the α−Al2O3 phase. It was determined that the value of hardness correlates with the content of the α−Al2O3 phase in the MAO coating, reaching the maximum value of 1620 kg/mm2 at the highest content (about 80 vol. %) of the α−Al2O3 phase.Two types of dependences of the coating thickness on the amount of electricity passed were revealed. For the amount of passed electricity 10–50 A-h/dm2, the thickness dependence is determined as 4.2 μm/(A-h/dm2), which suggests the basic mechanism of electrochemical oxidation during the formation of a coating. For the amount of electricity transmitted 50–120 A-hour/dm2, the thickness dependence is determined by a much smaller value of 1.1 μm/(A-hour/dm2). This suggests a transition to a different mechanism of coating formation − the formation of a coating with the participation of electrolysis componentsИсследовано влияние условий электролиза с разными составами электролита на кинетику роста, фазово-структурное состояние и твердость покрытий, полученных микродуговым оксидированием (МДО) на алюминиевом сплаве Д16 (основа – алюминий, основная примесь Cu).Анализ полученных результатов показал, что выбор типа электролита и условий протекания МДО-процесса позволяет в широких пределах изменять кинетику роста и фазово-структурное состояние покрытия на алюминиевом сплаве Д16. Для всех типов электролитов с увеличением содержания составляющих KOH, Na2SiO3 или KOH+Na2SiO3 повышается скорость роста МДО-покрытий.Установлено, что в МДО-покрытиях, получаемых в щелочном (KOH) электролите, формируется двухфазное (γ-Al2O3 и α-Al2O3 фазы) кристаллическое состояние. Увеличение концентрации KOH приводит к увеличению относительного содержания α−Al2O3 фазы (корунда). При формировании в силикатном электролите фазовый состав МДО-покрытий с увеличением содержания жидкого стекла (Na2SiO3) изменяется от смеси γ-Al2O3 фазы и муллита (3Al2O3•2SиO2) до рентгеноаморфной фазы. Использование комплексного электролита приводит к двухфазному состоянию покрытия с большим (по сравнению со щелочным электролитом) сдвигом превращения γ−Al2O3→α−Al2O3 в сторону образования α-Al2O3 фазы. Определено, что значение твердости коррелирует с содержанием α-Al2O3 фазы в МДО-покрытии, достигая наибольшей величины 1620 кг/мм2 при наибольшем содержании (около 80 об. %) α−Al2O3 фазы.Выявлено два типа зависимостей толщины покрытия от количества прошедшего электричества. Для количества прошедшего электричества 10 – 50 А-час/дм2 зависимость толщины определяется, как 4.2 мкм/(А-час/дм2), что предполагает базовый механизм электрохимического окисления при образовании покрытия. Для количества прошедшего электричества 50–120 А-час/дм2 зависимость толщины определяется значительно меньшей величиной 1.1 мкм/(А-час/дм2). Это предполагает переход к иному механизму формирования покрытия – образованию покрытия с участием компонентов электролизаДосліджено вплив умов електролізу з різними складами електроліту на кінетику росту, фазово-структурний стан і твердість покриттів, отриманих мікродуговим оксидуванням (МДО) на алюмінієвому сплаві Д16 (основа – алюміній, основна домішка Cu). Аналіз отриманих результатів показав, що вибір типу електроліту і умов протікання МДО-процесу дозволяє в широких межах змінювати кінетику росту і фазово-структурний стан покриття на алюмінієвому сплаві Д16. Для всіх типів електролітів зі збільшенням вмісту складових KOH, Na2SiO3 або KOH+Na2SiO3 підвищується швидкість росту МДО-покриттів. Встановлено, що в МДО-покриттях, одержуваних в лужному (KOH) електроліті, формується двофазне (γ-Al2O3 і α-Al2O3 фази) кристалічний стан. Збільшення концентрації KOH призводить до збільшення відносного вмісту α-Al2O3 фази (корунду). При формуванні в силікатному електроліті фазовий склад МДО-покриттів зі збільшенням вмісту рідкого скла (Na2SiO3) змінюється від суміші γ-Al2O3 фази і муллита (3Al2O3∙2SіO2) до рентгеноаморфної фази. Використання комплексного електроліту призводить до двофазного стану покриття з більшим (у порівнянні з лужним електролітом) зрушенням перетворення γ-Al2O3→α-Al2O3 в бік утворення α-Al2O3 фази. Визначено, що значення твердості корелює зі вмістом α-Al2O3 фази в МДО-покритті, досягаючи найбільшої величини 1620 кг/мм2 при найбільшому вмісті (близько 80 об. %) α-Al2O3 фази.Встановлено два типи залежностей товщини покриття від кількості електрики яке пройшло. Для кількості електрики яке пройшло 10–50 А-год/дм2 залежність товщини визначається, як 4.2 мкм/(А-годину/дм2), що передбачає базовий механізм електрохімічного окислення при утворенні покриття. Для кількості електрики яке пройшло 50–120 А-годину/дм2 залежність товщини визначається значно меншою величиною 1.1 мкм/(А-годину/дм2. Це передбачає перехід до іншого механізму формування покриття – утворення покриття за участі компонентів електроліз

A Novel Technique for Fiber Formation: Mechanotropic Spinning—Principle and Realization

We present basic experimental data and the theoretical background of a novel technique for fiber spinning from polymer solutions. The principal feature of the advanced process is realization of phase separation with detachment of a solvent, accompanied by the orientation of macromolecules, under the action of high extension rates. This is similar in some respects to dry spinning, though the driving force is not diffusion with subsequent evaporation of a solvent but redistribution of polymer-solvent interactions in favor of polymer-polymer and solvent-solvent ones governed by mechanical stresses. A promise of this approach has been demonstrated by experiments performed with polyacrylonitrile solutions in different solvents and solutions of the rigid-chain aromatic polyamide. We examined mechanotropic fiber spinning in model experiments with stretching jets from a drop of polymer solution in different conditions, and then demonstrated the possibility of realizing this process in the stable long-term continuous mode. During extension, phase separation happens throughout the whole section of a jet, as was confirmed by visual observation. Then a solvent diffuses on a jet surface, forming a liquid shell on the oriented fiber. Instability of this cover due to surface tension leads either to formation of separate solvent drops “seating” on the fiber or to the flow of a solvent down to the Taylor cone. The separate liquid droplets can be easily taken off a fiber. The physics underlying this process is related to the analysis of the influence of macromolecule coil-to-stretched chain transition on the intermolecular interaction