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Generalized Logan’s Problem for Entire Functions of Exponential Type and Optimal Argument in Jackson’s Inequality in L2（R3）

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Acta Mathematica Sinica,English Series 2018年第10期34卷 1563-1577页

作者： Valerii ivanov Alexey ivanov Department of Applied Mathematics and Computer Science Tula State University

We study Jackson＇s inequality between the best approximation of a function f∈ L2（R^3） by entire functions of exponential spherical type and its generalized modulus of continuity. We prove Jackson＇s inequality with the exact constant and the optimal argument in the modulus of continuity. In particular, Jackson＇s inequality with the optimal parameters is obtained for classical modulus of continuity of order r and Thue-Morse modulus of continuity of order r∈ N. These results are based on the solution of the generalized Logan problem for entire functions of exponential type. For it we construct a new quadrature formulas for entire functions of exponential type.

关键词： Best approximation generalized modulus of continuity Jackson's inequality optimal argument Logan's problem quadrature formula

Preparation and Properties of Foam Glass-ceramic from Diatomite

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Journal of Wuhan University of Technology(Materials Science) 2018年第2期33卷 273-277页

作者： ivanov KS Institute of the Earth Cryosphere Siberian Branch of Russian Academy of Sciences Tyumen 625026 Russia Tyumen Industrial University Tyumen 625000 Russia

The results of the study of raw mix preparation and foam glass-ceramics production using diatomite as a raw material were presented in the following article. A mixture of diatomite and 40% NaOH solution was subjected to heating at a constant temperature of 775 ℃. Samples of foam glass-ceramic from diatomite with an average density of 290-580 kg/m^3, compressive strength of 1.7-7.8 MPa and thermal conductivity of 0.08-0.14 W/（m·K） were obtained. The investigations have shown that the hydrothermal pretreatment of mixture at the temperature of 90 ℃ may lead to the acceleration of the leaching of amorphous SiO_2 from diatomite. It was discovered that the resulting soluble alkali silicates promote the process of foaming during heating and reduce the average density of the obtained samples. The optimal duration of the leaching process was estimated to be 30 minutes, which corresponds to the yield of SiO_2 equal to 42.5% by the weight of dry diatomite.

关键词： diatomite liquid glass foam glass-ceramics

An Overview of Rationalization Theories of Non-simply Connected Spaces and Non-nilpotent Groups

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Acta Mathematica Sinica,English Series 2022年第10期38卷 1705-1721页

作者： Sergei O.ivanov Laboratory of Modern Algebra and Applications St.Petersburg State University14th Line29bSaint Petersburg199178Russia

We give an overview of five rationalization theories for spaces(Bousfield-Kan’s Q-completion;Sullivan’s rationaliz ation;Bousifeld’s homology rationaliz ation;Casacuberta-Peschke’s Ω-rationalization;Gomez-Tato-Halperin-Tanré’s π-fiberwise rationalization)that extend the classical rationalization of simply connected *** also give an overview of the corresponding rationalization theories for groups(Q-completion;HQ-localization;Baumslag rationalization)that extend the classical Malcev completion.

关键词： Rationalisation localisation rational homotopy theory group theory

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功能与美学贝尔格莱德IT公司办公室

室内设计与装修 2025年第1期 16-21页

作者：无 Svetlana Dudina Dilyara Mukhamedova Vasilina Pavlova Evegeniya Sviridova Elena Menshikova Ilya ivanov(摄影) 夏花(编译) Nefa Architects 不详

该项目坐落在贝尔格莱德,是为一家国际IT公司设计的办公空间。项目的设计主旨不仅要能重现当地城市的景观多样性,也要体现其文化和历史的特质。设计师从南斯拉夫时期粗犷主义与现代主义的经典建筑风格中汲取灵感,通过原始混凝土元素,展... 详细信息

该项目坐落在贝尔格莱德,是为一家国际IT公司设计的办公空间。项目的设计主旨不仅要能重现当地城市的景观多样性,也要体现其文化和历史的特质。设计师从南斯拉夫时期粗犷主义与现代主义的经典建筑风格中汲取灵感,通过原始混凝土元素,展现城市的力量与质感;与此同时,设计融入明亮的色彩点缀,其灵感源于贝尔格莱德丰富的街头艺术作品。这些鲜明的艺术符号不仅为空间注入活力,还增强了视觉冲击力,使办公环境与城市特色无缝衔接,赋予空间独特的文化价值。

关键词：办公空间建筑风格街头艺术艺术符号办公环境无缝衔接注入活力景观多样性

Past climate and vegetation in Southeast Bulgaria——a study based on the late Miocene pollen record from the Tundzha Basin

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Journal of Palaeogeography 2019年第1期8卷 43-67页

作者： Dimiter ivanov Maria Lazarova Institute of Biodiversity and Ecosystem Research Bulgarian Academy of Sciences

The results of palynological studies on the late Miocene freshwater deposits of the Tundzha Basin(Southeast Bulgaria, SE Europe) are presented. The basin is relatively well known in terms of geology and *** age of sediments in the Tundzha Basin ranges between the late Miocene to the Pliocene, based on mammal and diatom fossils. We carried out a palynological analysis of clayey sediments interlayered with coal beds from four cores and from one outcrop, aiming to obtain information about the composition and the structure of fossil vegetation. The ratios between the main floristic elements and the composition of the fossil flora are analysed and discussed from a palaeoecological point of view. Several main vegetation palaeocommunities were recorded:swamp forests, mixed mesophytic, communities of aquatic plants, and herbaceous palaeocoenoses. The changes in vegetation and in plant diversity are identified. The palaeoclimate analysis indicates a warm temperature climate with high rainfall and mild winter temperatures, without seasonal drier conditions. The early Pontian climate was about 3–4 ℃ warmer than today, with rainfalls per year at least 300 mm higher than today. The results of palaeoecological analysis of the flora and of the quantitative palaeoclimate data show that the climate in the Southeast Bulgaria indicates a climate change towards slight cooling and some drying. This event is consistent with the period of accumulation of the upper, undivided part of the Elhovo Formation.

关键词： Palynology Palaeobotany Coexistence approach Neogene Tundzha Basin Bulgaria

Ordered exponential and its features in Yang-Mills effective action

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Communications in Theoretical Physics 2023年第8期75卷 119-127页

作者： A V ivanov N V Kharuk St.Petersburg Department of Steklov Mathematical Institute of Russian Academy of Sciences 27 FontankaSt.Petersburg 191023Russia Leonhard Euler International Mathematical Institute 10 Pesochnaya nab.St.Petersburg 197022Russia

In this paper,we discuss some non-trivial relations for ordered exponentials on smooth Riemannian *** an example of application,we study the dependence of the four-dimensional quantum Yang–Mills effective action on the special gauge transformation with respect to the background ***,we formulate some open questions about a structure of divergences for a special type of regularization in the presence of the background field formalism.

关键词： Yang-Mills effective action ordered exponential heat kernel Green's function short-distance asymptotics cutoff regularization Synge's world function

Transverse magnetoresistance peculiarities of thermoelectric Lu-doped Bi_2Te_3 compound due to strong electrical disorder

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Journal of Rare Earths 2019年第3期37卷 292-298页

作者： Oleg ivanov Maxim Yaprintsev Elena Danshina Belgorod State University Belgorod State Technological University named after V.G.Shukhov

The n-type thermoelectric Bi_(1.9)Lu_(0.1)Te_3 was prepared by microwave-solvothermal method and spark plasma sintering. The magnetic field and temperature dependences of transverse magneto resistance measured within temperature 2-200 K interval allow finding the peculiarities characteristic for strongly disordered and inhomogeneous semiconductors. The first peculiarity is due to appearance of linear-inmagnetic field contribution to the total magneto resistance reflected in a crossover from quadratic magnetoresistance at low magnetic fields to linear magneto resistance at high magnetic fields. The linear magnetoresistance can result from the Hall resistance picked up from macroscopically distorted current paths due to local variations in stoichiometry of the compound studied. The second peculiarity is that both linear magnetoresistance magnitude and crossover field are functions of carrier mobility which is in agreement with the Parish and Littlewood model developed for disordered and inhomogeneous semiconductors. An increase in the mobility due to a decrease in temperature is accompanied by an increase in the magnetoresistance magnitude and a decrease in the crossover field. Finally, the third peculiarity is related to the remarkable deviation of the total magnetoresistance measured at various temperatures from the Kohler's rule. Presence of strong inhomogeneity and disorder in the Bi_(1.9)Lu_(0.1)Te_3 structure concluded from the magnetoresistance peculiarities can be responsible for the remarkable reduction in the total thermal conductivity of this compound.

关键词： Bismuth telluride Linear positive magnetoresistance Semiconductors Thermoelectric material Carrier mobility Kohler’s rule

Soil respiration in paludified forests of European Russia

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Journal of Forestry Research 2020年第5期31卷 1939-1948页

作者： Dmitry ivanov Fedor Tatarinov Julia Kurbatova A.N.Severtsov Institute of Ecology and Evolution RAS Leninsky Prospekt 33MoscowRussia 119071 Weizmann Institute of Science Herzl St 23476100 RehovotIsrael

Soil respiration studies in paludified forests of the European part of Russia are quite rare in comparison with those of open peat bogs,which make long-term observations in this region highly *** this study,soil CO2 emissions were measured by the close chamber method in different microlandscapes of paludified *** four summer seasons with different environments,soil respiration ranged from 1078 to 248 mg CO2 m^-2 h^-1 in a paludified spruce forest site with coarse woody debris to 659–820 mg CO2 m^-2 h^-1 in a paludified boggy pine *** most intensive soil respiration was observed during the hot summer of 2013 and the lowest in the hot and humid summer of *** total soil CO2 emissions in paludified forests in 2015–2016 were approximately 2000–3000 g CO2 *** the year,the lowest CO2 emission values were observed from November to April(14–84 mg CO2 m^-2 h^-1)and the maximum were in July and August(522–1205 mg CO2 m^-2 h^-1).The contributions of CO2 emissions in the cold November–April period were 6–8.5%.The impacts of temperature on soil respiration were higher(r2=0.45–0.57)than those of groundwater levels(r^2=0.17–0.49).Soil respiration in the paludified spruce forest and in the pine bog generally were higher than emissions from ecosystems with similar hydrothermal conditions in the boreal zone.

关键词： Carbon flux Chamber measurements CO2 emission Peatlands Southern taiga

A Variational Principle and Best Proximity Points

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Acta Mathematica Sinica,English Series 2015年第8期31卷 1315-1326页

作者： Milen ivanov Boyan ZLATANOV Nadia ZLATEVA Faculty of Mathematics and Informatics Sofia University "St.Kliment Ohridski" 5James Bourchier blvd.1164 Sofia Bulgaria Faculty of Mathematics and Informatics Plovdiv University "Paisii Hilendarski"24 "Tsar Assen"str.4000 Plovdiv Bulgaria Faculty of Mathematics and Informatics Sofia University "St.Kliment Ohridski"5James Bourchier blvd.1164 Sofia Bulgaria

We generalize Ekeland＇s Variational Principle for cyclic maps. We present applications of this version of the variational principle for proving of existence and uniqueness of best proximity points for different class... 详细信息

关键词： Fixed point cyclical operator best proximity point uniformly convex Banach space variational principle