164 research outputs found
Нижний город Танаиса
No full textSituated near the point where the Tanais River (the modern Don) flowed into Lake Maeotis (the modern Sea of Azov), the Greek
colony of Tanais was located on the frontier of the ancient Greek world. Founded in the first quarter of the 3rd century B.C. as a small trading settlement, the city gradually became a large center of commerce and a major emporion. The systematic excavations at this site began in 1955, but after almost one hundred and fifty years, the size of the ancient city, as well as its precise topography and lay-out, still remain largely unknown. From the 1990s onwards, more archaeological work has been undertaken in the territory of the Upper City
outside the main part of the settlement, bringing to light new evidence. The part of the city about which we know the least is the area to the south of the citadel, where the Lower City must have been located. The present article discusses all available evidence that may help us to reconstruct the diachronic development of the Lower City of Tanais and indicate the possible location of the ancient harbor. В настоящей статье на основе археологических данных детально реконструируется развитие Нижнего города Танаиса, а также проводится анализ сведений, помогающих определить возможное расположения древней гавани.Список литературы: с. 93; текст статьи снабжен многочисленными иллюстрациями
Dulac's Theorem Revisited
No full textDulac's theorem states that the number of limit cycles of any given polynomial vector field on the plane is finite. After compactifying the phase plane to a sphere and some well known arguments one only has to prove that limit cycles cannot accumulate onto elementary graphics which we will call polycycles. Dulac in his proof unfortunately made an unproved statement by inferring the triviality of the return map of a polycycle from the triviality of its asymptotic expansion. Ilyashenko in (Russ Math Surv 40(6):1-49, 1985. https://doi.org/10.1070/rm1985v040n06abeh003701) produced a clever counter example, clearly showing why Dulac's arguments failed and additionally he showed that Dulac's theorem is valid for hyperbolic polycycles, i.e. polycycles with only hyperbolic equilibria. It is a corner stone that has been completely understood. Afterwards Ilyashenko published his own full proof of Dulac's theorem in Ilyashenko (in: Translations of mathematical monographs, American Mathematical Society, Providence, 1991). We provide evidence that the approach of Ilyashenko (1991) to the proof of Dulac's theorem has a gap. Although the asymptotics of Ilyashenko (1991) capture far more than the asymptotics of Dulac, we prove that the arguments for why the asymptotics in Ilyashenko (1991) are not themselves oscillatory is insufficient. We give an explicit counterexample and we draw confines to which Ilyashenko's result may be restricted in order to keep the validity.This work was supported by ‘Research Foundation - Flanders, FWO’ file number 11E6821N
The author would like to thank Dmitry Novikov for helping him understand the quasianalyticity arguments of Ilyashenko and for the feedback on this article. The author is very grateful to Daniel Panazzolo for organizing a workshop for the author to present his findings and for the feedback on this article. The author thanks his promotor Peter de Maesschalck for introducing him to this problem and for the extensive feedback on this article. The author would like to thank Freddy Dumortier for providing feedback on this article. The author is thankful to Yulij S. Ilyashenko for providing feedback on this article
Analysis of the efficiency of using heat exchangers with porous inserts in heat and gas supply systems
No full textThe creation of efficient and compact heat exchangers is one of the priority tasks arising during the design of heat and gas supply to industrial and residential buildings. As a rule, finned surfaces and turbulization of heat carrier flows are used to increase the efficiency of heat exchange in heat exchangers. The present paper proposes to use novel materials, namely porous material, in the design of highly efficient heat exchangers. The investigation was carried out experimentally and theoretically. To study the possibility of creating such heat exchangers, a multi-purpose test bench is created. The aim of the study was to assess the intensity of heat transfer in heat exchangers using porous metal. Laboratory tests are carried out as part of the experimental study. In the theoretical study, the classical equation for the change in the heat flux density when the coolant passes through the porous insert was used. As a result, a mathematical model was obtained in the form of a second-order differential equation. Boundary conditions were set and a particular solution was obtained. The results of theoretical calculations were compared with experimental data. The performed study experimentally confirmed the efficiency of using porous metal inserts in the design of shell-and-tube heat exchangers. The compiled mathematical model allows one to perform engineering calculations of the considered heat exchangers with porous inserts
Financial and economic aspects of corporate social responsibility
No full textThe article shows the importance of corporate social responsibility (CSR) in ensuring sustainable development of the country. The types of CSR and its features in various states are considered. The author describes the economy of the Russian Federation and its impact on the system of corporate social responsibility in the country. The high profitability of resource-extractive industries and their use of the country’s national wealth defines their special role in CSR not only towards their employees through wages and the allocation of social benefits from profit, but also to the society. It is shown that the established country’s political system significantly influences the possibility of implementing a system of corporate social responsibility. The author characterizes the significant regulatory and stimulating role of the state in social development through taxation and the structure of government spending. When assessing the financial conditions of CSR, the author analyses the impact of capital outflow on its development. Corporate social responsibility also includes the responsibility of organizations to the environment. The author provides a rating assessment of Russian oil and gas, mining and metallurgical companies openness in terms of environmental responsibility
Catalytic and mechanistic studies into the epoxidation of styrenes using manganese complexes of structurally similar polyamine ligands
No full textFrom new documents to the history of the Siverian region (17th–18th centuries) (part 20)
No full textThe publication presents documents of hetman Ivan Mazepa and colonels Ilya Novytsky, Maksym Ilyashenko, Leontiy Svichka, Tymofiy Zhoravka and other officers. Various business documents of merchants, complaints of Siverian region in XVII-XVIII centuries are presented also
Financial-Economic problems of innovative agricultural development in Russia
No full textThe article discusses the economic problems of the innovative development of agriculture in the Russian Federation. The author describes the features of this process in agriculture that impede the introduction of innovations. As a result, the problems of innovative development that are characteristic of the economy as a whole under the specific conditions of agricultural production are intensified. Analyzing statistics, the author shows that the import substitution policy in agriculture in Russia is not fully implemented. The article describes the interconnection of the innovation process with the development and implementation of research and development and investment activity in the industry. The article analyzes the problems of using both own and attracted financial resources for innovative development. The author shows the problem of disparity in prices for agricultural and industrial products. The article also underlines the relationship of innovation and investment in human capital, the formation of human resources. The author makes the conclusions and proposals to stimulate the innovative development of agriculture
Electrical properties of the sensitive side in Si edgeless detectors
No full textSilicon edgeless detectors represent a novel type of detector that are being developed for close-to-beam applications in high-energy physics and for large-scale tiled 1D and 2D arrays used in radiation imaging. In this work, the electric field and potential distributions on the device cut side, key factors in detector performance, have been investigated using two methods—the Conductive Microprobe Technique and the Scanning Transient Current Technique. It has been found that the behaviour of the potential distribution at the edge indicates a significant presence of positively charged states, with the charge density changing with the applied voltage. This work will predict, to a first approximation, the trend of the electric field at the edge of these devices after irradiation to high fluences. This prediction will provide key inputs in the development of edgeless radiation hard detectors
Complex length and persistence of limit cycles in a neighborhood of a hyperbolic polycycle
No full textThe author was partially supported by the grants NSF 0700973 and CNRS-RFBR 10-01-93115-NTSNILa.Complex limit cycle located in a neighborhood of a hyperbolic polycycle can not vanish under a small deformation that preserves the characteristic values of the vertexes of the polycycle. The cycles either change holomorphically under the change of the parameter, or come to the boundary of the fixed neighborhood of the polycycle. The present paper makes these statements rigorous and proves them
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