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128 results on '"Sadchikov A. P."'

1. The role of rotifer in water quality improvement in a fishpond

Author

Gerasimova T. N. and Sadchikov A. P.

Subjects
rotifers, artificial food, temperature, water quality, fish pond, коловратки, искусственный корм, температура, качество воды, рыбоводный пруд, General Works
Abstract

Rotifers are common in fresh and brackish water bodies, in coastal areas of the seas, and can be an effective tool for analyzing the state of the environment. The ability of rotifers to adapt to unfavourable environmental conditions has been considered in the course of studying the species composition of rotifers in a fish pond near Moscow under the conditions of the supply of organic artificial food for fish and changes in the temperature regime of water. During the period of increased temperature of the water (21–25 °C) and decrease in the concentration of dissolved oxygen from the surface to the bottom layers of water from 3.8 to 0.2 mgO2/L in early July, Asplanchna priodonta helvetica, Brachionus angularis angularis and Brachionus calyciflorus dominated in the pond (98–100 % of the abundance and 99–100 % of the biomass of rotifers). During the period of elevated temperatures, the turbidity indices in the upper layer (0.2–0.5 m) were an order of magnitude lower than those in the deeper layers of the reservoir. Bacteria and tiny particles served as food for rotifers. The temperature of 18–25 °C was favourable for the development of B. angularis angularis in the fish pond. At a temperature of 18 °C, its abundance reached 1,500 ind./L (70 % of the abundance of rotifers). In August, when the temperature of the water column decreased from 20 to 18 °C, the biomass of A. priodonta helvetica changed from 0.3 to 9.5 mg/L (99 % of the biomass of rotifers). Polyarthra vulgaris dominated among small rotifers. During the period of low temperatures, the biomass of rotifers increased to 20 mg/L; its basis was A. priodonta helvetica. Rotifers are able to adapt to conditions of high organic input in a wide range of temperatures and participate in the restoration of water quality in a fish pond.

Published
2022
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2. Local SGD for Near-Quadratic Problems: Improving Convergence under Unconstrained Noise Conditions

Author

Sadchikov, Andrey, Chezhegov, Savelii, Beznosikov, Aleksandr, and Gasnikov, Alexander

Subjects
Mathematics - Optimization and Control
Abstract

Distributed optimization plays an important role in modern large-scale machine learning and data processing systems by optimizing the utilization of computational resources. One of the classical and popular approaches is Local Stochastic Gradient Descent (Local SGD), characterized by multiple local updates before averaging, which is particularly useful in distributed environments to reduce communication bottlenecks and improve scalability. A typical feature of this method is the dependence on the frequency of communications. But in the case of a quadratic target function with homogeneous data distribution over all devices, the influence of frequency of communications vanishes. As a natural consequence, subsequent studies include the assumption of a Lipschitz Hessian, as this indicates the similarity of the optimized function to a quadratic one to some extent. However, in order to extend the completeness of the Local SGD theory and unlock its potential, in this paper we abandon the Lipschitz Hessian assumption by introducing a new concept of $\textit{approximate quadraticity}$. This assumption gives a new perspective on problems that have near quadratic properties. In addition, existing theoretical analyses of Local SGD often assume bounded variance. We, in turn, consider the unbounded noise condition, which allows us to broaden the class of studied problems., Comment: 33 pages, 1 algorithm, 3 figures, 2 tables

Published
2024
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10. Educational Game Systems in Artificial Intelligence Course

Author

Chubarkova, Elena V., Sadchikov, Ilya A., Suslova, Irina A., Tsaregorodtsev, Andrey ?, and Milova, Larisa N.

Abstract

Article actuality based on fact that existing knowledge system aimed at future professional life of students: a skillful use game activity in educational process will teach students to look for alternative ways solving of real problems. The purpose of article lies in theoretical substantiation, development and testing of criteria, which must be met by special-purpose software oriented on gamification of educational process. A leading research method of the described problem is a method of simulation that allows to consider gamification as concentration and organized process for increasing the factor of student engagement in cognitive activity. This article aimed to demonstrate models of ideal educational game programs with optimum number of gamification elements, also article focused on development of such software, which will be not entertaining, but educational in nature. The article may be useful for researchers dealing with gamification issues and software developers, which works relate with educational programs.

Published
2016

18. Indoor Characterization of Solar Concentrator SMALFOC Modules Through Cell-to-Ambient Thermal Resistance Measurements

Author

Sadchikov, N. A., Davidyuk, N. Y., Malevskiy, D. A., Pokrovskiy, P. V., Andreeva, A. V., and Larionov, V. R.

Abstract

To evaluate the overheating temperature of solar cells in concentrator photovoltaic (CPV) modules during solar radiation conversion, we propose a method for determining the thermal resistivity between the solar cell and its environment (rth) in laboratory conditions at room temperature and in the absence of forced ventilation. The essence of this method is the measurement of the temperature change of the solar cells inside the CPV module under thermal load generated by direct current flow through the solar cell. The change in temperature of the solar cells in CPV modules under thermal load is determined by calculating the voltage difference across the module contacts during fast measurements of the I–V curve at room temperature and the I–V curve when the solar cells of the module are heated by direct current. The developed methodology eliminates uncertainties associated with the location of temperature sensors and unstable meteorological conditions. In the present work, this technique is used to study the overheating temperature of solar cells of “Small lenses, Multijunction cells, All from glass, Lamination, Fresnel, Optics, Concentration” design CPV modules varying in materials and thicknesses of heat sinks. In laboratory conditions, we determined the values of rth of small CPV modules and full-size CPV modules, containing, respectively, 8 and 128 pairs of Fresnel lens—triple-junction InGaP/InGaAs/Ge solar cells soldered to a metal heat sinks of similar design. Copper or steel was used as materials for the heat sinks.

Published
2024
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48. Shape of collective flow in highly central Au(150 A MeV)+Au collisions

Author

Roy, C., Kuhn, C., Coffin, J. P., Crochet, P., Fintz, P., Guillaume, G., Jundt, F., Maazouzi, C., Rami, F., Tizniti, L., Wagner, P., Alard, J. P., Amouroux, V., Basrak, Z., Bastid, N., Belyaev, I., Best, D., Biegansky, J., Buta, A., Čaplar, R., Cindro, N., Donà, R., Dupieux, P., Dzelalija, M., Fan, Z. G., Fodor, Z., Fraysse, L., Gobbi, A., Herrmann, N., Hildenbrand, K. D., Hölbling, S., Hong, B., Jeong, S. C., Kecskemeti, J., Kirejczyk, M., Koncz, P., Korchagin, Y., Kotte, R., Lebedev, A., Legrand, I., Leifels, Y., Manko, V., Mgebrishvili, G., Moisa, D., Mösner, J., Neubert, W., Pelte, D., Petrovici, M., Pinkenburg, C., Pras, P., Reisdorf, W., Ritman, J. L., Sadchikov, A. G., Schüll, D., Seres, Z., Sikora, B., Simion, V., Smolyankin, V., Sodan, U., Trzaska, M., Vasiliev, M., Wang, G. S., Wessels, J. P., Wienold, T., Wohlfarth, D., Zhilin, A., Konopka, J., and Stöcker, H.

Published
1997
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