Jamming and percolation of parallel squares in single-cluster growth model

This work studies the jamming and percolation of parallel squares in a single-cluster growth model. The Leath-Alexandrowicz method was used to grow a cluster from an active seed site. The sites of a square lattice were occupied by addition of the equal size $k \times k$ squares (E-problem) or a mixture of $k \times k$ and $m \times m$ ($m \leqslant k$) squares (M-problem). The larger $k \times k$ squares were assumed to be active (conductive) and the smaller $m \times m$ squares were assumed to be blocked (non-conductive). For equal size $k \times k$ squares (E-problem) the value of $p_j = 0.638 \pm 0.001$ was obtained for the jamming concentration in the limit of $k\rightarrow\infty$. This value was noticeably larger than that previously reported for a random sequential adsorption model, $p_j = 0.564 \pm 0.002$. It was observed that the value of percolation threshold $p_{\mathrm{c}}$ (i.e., the ratio of the area of active $k \times k$ squares and the total area of $k \times k$ squares in the percolation point) increased with an increase of $k$. For mixture of $k \times k$ and $m \times m$ squares (M-problem), the value of $p_{\mathrm{c}}$ noticeably increased with an increase of $k$ at a fixed value of $m$ and approached 1 at $k\geqslant 10m$. This reflects that percolation of larger active squares in M-problem can be effectively suppressed in the presence of smaller blocked squares.Comment: 11 pages, 9 figure

Percolation of the aligned dimers on a square lattice

Percolation and jamming phenomena are investigated for anisotropic sequential deposition of dimers (particles occupying two adjacent adsorption sites) on a square lattice. The influence of dimer alignment on the electrical conductivity was examined. The percolation threshold for deposition of dimers was lower than for deposition of monomers. Nevertheless, the problem belongs to the universality class of random percolation. The lowest percolation threshold (pc = 0.562) was observed for isotropic orientation of dimers. It was higher (pc = 0.586) in the case of dimers aligned strictly along one direction. The state of dimer orientation influenced the concentration dependence of electrical conductivity. The proposed model seems to be useful for description of the percolating properties of anisotropic conductors.Comment: 6 pages, 9 figures, submitted to EPJ

ИССЛЕДОВАНИЕ ВОЗМОЖНОСТИ ПРИМЕНЕНИЯ ВИХРЕВОГО ТЕПЛОГЕНЕРАТОРА В СИСТЕМАХ ТЕПЛОСНАБЖЕНИЯ ЖИЛЫХ, ПРОМЫШЛЕННЫХ И ОБЩЕСТВЕННЫХ ЗДАНИЙ

In a number of foreign countries, vortex heat generators have become widespread in decentralized heat supply systems. For Belarus, vortex heat generators are quite new sources of heat supply. The article considers the possibility of using vortex heat generators for heat supply systems for residential, public and industrial buildings. Vortex heat generators are based on the principle of cavitation in a turbulent water flow. For many devices cavitation is not desirable, but in a vortex heat generator it is used as a favorable phenomenon. The authors carried out a series of full-scale experiments to determine the efficiency of the “VTG-2.2” vortex heat generator when different operating modes were applied. The performance of the vortex heat generator can be estimated by the energy conversion factor. Energy conversion factor is the ratio of the amount of thermal energy that a vortex heat generator generates to the amount of electrical energy consumed. Experiments conducted in a number of research organizations (including the National Academy of Sciences of Ukraine and MPEI) have demonstrated that energy conversion factor can exceed 1. The authors conducted experimental tests with the use of an experimental installation simulating a heat supply system. According to the obtained experimental data, the energy conversion coefficients for each mode were calculated. The constructed graphical dependencies clearly demonstrate that, with increasing rotational speed of the vortex heat generator, the efficiency of its use increases. The highest energy conversion factor value was 61.1 % with a rotation frequency of 40 Hz. It was also found that with increasing the rotational speed of the vortex heat generator, a significant increase in noise and vibration occurs.В ряде зарубежных стран вихревые теплогенераторы получили широкое распространение в системах децентрализованного теплоснабжения. Для Беларуси вихревые тепловые генераторы – это пока достаточно новые источники теплоснабжения. В статье рассматривается возможность применения вихревых теплогенераторов для систем теплоснабжения жилых, общественных и промышленных зданий. Вихревые теплогенераторы основаны на принципе кавитации в турбулентном потоке воды. Для многих устройств кавитация не желательна, но в вихревом теплогенераторе она используется как положительное явление. Авторами выполнены серии натурных экспериментов для определения эффективности работы вихревого теплогенератора марки ВТГ-2,2 на разных режимах работы. Эффективность работы вихревого теплогенератора можно оценить коэффициентом преобразования энергии. Коэффициент преобразования энергии – это отношение количества тепловой энергии, которую производит вихревой теплогенератор, к количеству потребляемой электрической энергии. Опыты, проводимые в ряде научно-исследовательских организаций (в том числе в НАН Украины, МЭИ), показали, что коэффициент преобразования энергии может превышать единицу. Авторы выполняли испытания на экспериментальной установке, имитирующей систему теплоснабжения. По полученным экспериментальным данным были рассчитаны коэффициенты преобразования энергии для каждого режима. Построенные графические зависимости наглядно показывают, как с увеличением частоты вращения вихревого теплогенератора повышается эффективность его использования. Наибольшее значение коэффициента преобразования энергии составило 61,1 % при частоте вращения 40 Гц. Также выявлено, что с увеличением частоты вращения вихревого теплогенератора происходит значительное увеличение шума и вибраций

On The 100th Anniversary Of The Founder Of The Odessa Scientific School Of Economic Thought A. K. Pokrytan

The partnership between the Odessa National University of Economics and "D. A. Tsenov” Academy of Economics is an example of a successful model for adding value in the field of scientific research. With its annual scientific conferences, the Odessa National University of Economics has provided dozens of scientists from the Svishtov Academy and other foreign researchers with the opportunity to publish their papers abroad. Prof. Mihail Zveryakov himself is a Doctor Honoris Causa (Zastrahovatel.com, 2010) of D. A. Tsenov Academy and a prominent co-author in collaborative research publications indexed in SCOPUS Q1/WoS (Zahariev, et al., 2020). The paper commemorates and pays due respect to Prof. Anatoly Karpovich Pokrytan - one of the most prominent scientists in the field of economics whose centenary provided his scientific followers with the opportunity to reflect on his scientific legacy. The 100th anniversary of the establishment of the Odessa National Economic University in Ukraine (founded under the name Odessa Institute of National Economy) on 16 May 1921 is another evidence for our Ukrainian partner’s tenacity during the decades of intense socio-economic and ideological changes of the 20th and the 21st century

Internal scheme of the body assessment in an experiment with environmental uncertainty

The aim of the work was to analyze the influence of various environmental factors forming environmental uncertainty on the nature of the transformation of the "internal scheme of the body". Materials and methods. For the study, a group of healthy volunteers (n = 90) was selected. The results in this paper are median, 75 and 25 percentiles (Me [UQ / LQ]). The study was conducted in several stages. At the first stage, the criteria for excluding potential participants from the experiment were formed. At the second stage of the study, a video analysis of the main anatomical orientations of the pelvic region in static and dynamic samples was conducted for all participants. Conclusion. In the course of the study, specific patterns of spatial deviations of biomechanical blocks of the pelvic region were established, triggered by changes in the qualitative and quantitative parameters of the external environment. So, in conditions of static equilibrium, coordination is activated with involvement of the anterior and posterior half-rings of the pelvis (frontal biomechanical blocks); in conditions of dynamic equilibrium, diagonal biomechanical blocks of the pelvic region are activated; in conditions of deprivation of visual afferentation, the compensatory reactions of the lateral semirings of the pelvic region (lateral biomechanical blocks) are formed

Классификация криогенно-оползневых форм рельефа для целей картографирования и прогноза

A classification of cryogenic-landslide landforms is developed for mapping their distribution and dynamics. It is based on the previously suggested classification subdividing cryogenic landsliding into two main types: cryogenic translational landslides (or active-layer detachment slides), and cryogenic earth flows (or retrogressive thaw slumps). The increased proportion of retrogressive thaw slumps compared to active layer detachments in the North of West Siberia in the last decade creates the need for an expanded classification of cryogenic earth flows. One of the important issues is separating the process of landsliding and resulting landforms, which in English are covered by one term ‘retrogressive thaw slump’. In dealing with the landforms, we distinguish (1) open and (2) closed ones. Open cryogenic-landslide landforms are those formed by the retreating of the coast bluff due to the thaw of ice or ice-rich deposits with an additional impact from wave or stream action. Closed cryogenic-landslide landforms are those initiated on a slope landward, and thawed material is delivered to the coast or stream through an erosional channel. Morphologically we distinguish thermocirques and thermoterraces depending on the shape of the retreating headwall, crescent or linear, respectively. An important issue is the type of ground ice subjected to thaw: tabular, ice-wedge or constitutional ground ice are distinguished. Landforms can be active, stabilized or ancient. One can find both single landforms and their combination. The classification is based on a significant amount of field studies and interpretation of remote sensing data. Mapping of the cryogenic-landslide landforms is suggested using the proposed classification and indication features. The classification is based on the experience obtained mainly in the north of West Siberia. Applying it to other regions may require additional studies.Разработана классификация криогенно-оползневых форм рельефа, сформированных криогенными оползнями течения (КОТФР), для картографирования их распространения и динамики. В основе лежит значительный объем полевых исследований и интерпретации данных дистанционного зондирования Земли. Классификация включает генетические, морфологические и криолитологические особенности пород, определяющие морфологию и динамику КОТФР, их положение в рельефе, степень их активности, сочетание и комплексирование единичных КОТФР. Предложенная классификация и индикационные признаки используются для картографирования КОТФР на севере Западной Сибири

Correlation effects during liquid infiltration into hydrophobic nanoporous mediums

Correlation effects arising during liquid infiltration into hydrophobic porous medium are considered. On the basis of these effects a mechanism of energy absorption at filling porous medium by nonwetting liquid is suggested. In accordance with this mechanism, the absorption of mechanical energy is a result expenditure of energy for the formation of menisci in the pores on the shell of the infinite cluster and expenditure of energy for the formation of liquid-porous medium interface in the pores belonging to the infinite cluster of filled pores. It was found that in dependences on the porosity and, consequently, in dependences on the number of filled pores neighbors, the thermal effect of filling can be either positive or negative and the cycle of infiltration-defiltration can be closed with full outflow of liquid. It can occur under certain relation between percolation properties of porous medium and the energy characteristics of the liquid-porous medium interface and the liquid-gas interface. It is shown that a consecutive account of these correlation effects and percolation properties of the pores space during infiltration allow to describe all experimental data under discussion

Nonlinear dynamics of magnetohydrodynamic flows of heavy fluid over an arbitrary surface in shallow water approximation

The magnetohydrodynamic equations system for heavy fluid over an arbitrary surface in shallow water approximation is studied in the present paper. It is shown that simple wave solutions exist only for underlying surfaces that are slopes of constant inclination. All self-similar discontinuous and continuous solutions are found. The exact explicit solutions of initial discontinuity decay problem over a flat plane and a slope are found. It is shown that the initial discontinuity decay solution is represented by one of five possible wave configurations. For each configuration the necessary and sufficient conditions for its realization are found. The change of dependent and independent variables transforming the initial equations over a slope to those over a flat plane is found.Comment: 43 pages, submitted to Theoretical and Computational Fluid Dynamic

Синтез и свойства новых азотсодержащих производных зерумбона

A series of potential bioactive nitrogen zerumbone derivatives by carbonyl group containing terpene ring, has been synthesized. For the first time, microwave irradiation method has been used for their preparation. The structures of the obtained compounds have been determined by 1Н NMR and IR spectroscopy.Синтезирован ряд потенциальных биологически активных азотсодержащих производных зерумбона по карбонильной группе с сохранением терпенового цикла. Впервые такой синтез проведен с использованием метода микроволнового излучения. Методами ЯМР1Н и ИК спектроскопии установлено строение полученных соединений