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Plasma-assisted oxidation of benzoic acid

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Frontiers of Chemical science and Engineering 2020年第4期14卷 513-521页

作者： Anna Khlyustova nikolay sirotkin Laboratory of Chemistry of Hybrid Nanomaterials and supermolecular systems G.A.Krestov Institute of Solution Chemitry of Russian Academy of SciencesIvanovo 153045Russia

Plasma-assisted oxidation of organic com-pounds is one of the developing technologies for wastewater *** effectively accelerate degradation processes due to plasma generated reactive species and ultra-violet *** of BA in aqueous solutions by the atmospheric pressure glow discharge and underwater diaphragm discharge was studied and monitored by fluorescence and spectrophoto-metric *** type and solution pH affect the formation rates of mono-and dihydroxybenzoic *** derivatives were formed only by glow discharge *** yields of hydroxyl radical were estimated on the kinetics data for the hydroxylation of benzoic *** steps of the hydroxylation processes and further oxidation were described.

关键词： atmospheric pressure glow discharge under-water diaphragm discharge oxidation benzoic acid hydroxyl radical

saffman–Taylor instability in eccentric cylinders at gaseous cavitation

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Friction 2024年第2期12卷 356-362页

作者： Anatoliy A.MONAKHOV nikolay BUKHARIN Institute of Mechanics Moscow State UniversityMoscow 119899Russia ThermoFluid solutions Ltd. CalgaryAlberta T3G4E8Canada

A flow of silicon fluid in the gap between eccentric cylinders was studied *** condition of gaseous cavitation inception during the rotation of internal cylinder was *** was shown that at reduction of the gap between cylinders saffman–Taylor instability appeared on surface of the internal cylinder and then gaseous cavitation was *** of one uniform gas formation appearance under this type of instability was demonstrated.

关键词： gaseous cavitation saffman-Taylor instability eccentric cylinders friction lubrication theory

EXIsTENCE OF sOLUTIONs OF nTH-ORDER NONLINEAR DIFFERENCE EQUATIONs WITH GENERAL BOUNDARY CONDITIONs

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Acta Mathematica scientia 2020年第1期40卷 226-236页

作者： Alberto CABADA nikolay DIMITROV Departamento de Estatística Análise Matemática e OptimizaciónInstituto de MatemáticasFacultade de MatemáticasUniversidade de Santiago de CompostelaSantiago de CompostelaGaliciaSpain Depatment of Mathematics University of RuseRuse 7000Bulgaria

The aim of this paper is to prove the existence of one or multiple solutions of nonlinear difference equations coupled to a general set of boundary *** to do this,we construct a discrete operator whose fixed points coincide with the solutions of the problem we are looking ***,we introduce a strong positiveness condition on the related Green's function that allows us to construct suitable cones where to apply adequate fixed point *** we have the general existence result,we deduce,as a particular case,the existence of solutions of a second order difference equation with nonlocal perturbed Dirichlet conditions.

关键词： difference equation multiplicity of solutions Green's function positive solutions parameter dependence

Optimal control of natural resources in mining industry

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International Journal of Mining science and Technology 2015年第2期25卷 193-198页

作者： Petrov nikolay Tanev Angel Electrical Engineering Electronics and AutomationTechnical University-Sofia Faculty of Mathematics and Informatics Sofia University

The paper focuses on the optimal control of natural resources in mining industry. The purpose is to pro- pose an optimal extraction series of these resources during the lifetime of the Mine＇s maintenance. Fol- lowing the proposed optimal control model, a sensitivity analysis has been performed that includes the interest rate impact on the optimal solution. This study shows that the increasing of the interest rate sti- mulates faster extraction of the resources. The discounting factor induces that the resource has to be extracted faster hut this effect is counterbalanced by the diminishing returns of the annual cash flow. At higher parameters of ＂alpha＂ close to one of the power function about 80% from the whole resource will be extracted during the first 4 years of object/mine maintenance. An existence of unique positive root with respect to return of investment has been proposed and proved by two ways： by the ＂method of chords＂ and by using specialized software.

关键词： Optimal control Natural resources Interest rate sensitivity analysis Method of chords

On Concept Lattices for Numberings

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TsINGHUA sCIENCE AND TECHNOLOGY 2024年第6期29卷 1642-1650页

作者： Bazhenov, nikolay Mustafa, Manat Nurakunov, Anvar sobolev Inst Math Lab Computabil Theory & Appl Log Novosibirsk 630090 Russia Nazarbayev Univ Sch Sci & Humanities Dept Math Astana 010000 Kazakhstan Natl Acad sci Inst Math Bishkek 720071 Kyrgyzstan

The theory of numberings studies uniform computations for families of mathematical objects. In this area, computability-theoretic properties of at most countable families of sets s are typically classified via the corresponding Rogers upper semilattices. In most cases, a Rogers semilattice cannot be a lattice. Working within the framework of Formal Concept Analysis, we develop two new approaches to the classification of families s. similarly to the classical theory of numberings, each of the approaches assigns to a family s its own concept lattice. The first approach captures the cardinality of a family s: if s contains more than 2 elements, then the corresponding concept lattice FC1(s) is a modular lattice of height 3, such that the number of its atoms to the cardinality of s. Our second approach gives a much richer environment. We prove that for any countable poset P, there exists a family s such that the induced concept lattice FC2 (s) is isomorphic to the Dedekind-MacNeille completion of P. We also establish connections with the class of enumerative lattices introduced by Hoyrup and Rojas in their studies of algorithmic randomness. We show that every lattice FC2 (s) is anti-isomorphic to an enumerative lattice. In addition, every enumerative lattice is anti-isomorphic to a sublattice of the lattice FC2 (s) for some family s.

关键词： theory of numberings concept lattice index set complete lattice enumerative lattice Formal Concept Analysis

FINITE TIME BLOW UP OF THE sOLUTIONs TO BOUssINEsQ EQUATION WITH LINEAR REsTORING FORCE AND ARBITRARY POsITIVE ENERGY

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Acta Mathematica scientia 2016年第3期36卷 881-890页

作者： nikolay kutev natalia kolkovska milena dimova Institute of Mathematics and Informatics Bulgarian Academy of Sciences 1113 Sofia Bulgaria

Finite time blow up of the solutions to Boussinesq equation with linear restoring force and combined power nonlinearities is studied. sufficient conditions on the initial data for nonexistence of global solutions are derived. The results are valid for initial data with arbitrary high positive energy. The proofs are based on the concave method and new sign preserving functionals.

关键词： Boussinesq equation with linear restoring force finite time blow up arbitrary high positive energy combined power nonlinearities sign preserving functionals

EXIsTENCE OF sOLUTIONs OF NONLOCAL PERTURBATIONs OF DIRICHLET DIsCRETE NONLINEAR PROBLEMs

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Acta Mathematica scientia 2017年第4期37卷 911-926页

作者： Alberto CABADA nikolay D.DIMITROV Instituto de Matemdticas Facultade de MatemdticasUniversidade de Santiago de Compostela15782 Santiago de CompostelaSpain Department of Mathematical Analysis University of Rousse7017 RousseBulgaria

This paper is devoted to the study of second order nonlinear difference equations. A Nonlocal Perturbation of a Dirichlet Boundary Value Problem is considered. An exhaustive study of the related Green＇s function to the linear part is done. The exact expression of the function is given, moreover the range of parameter for which it has constant sign is obtained. Using this, some existence results for the nonlinear problem are deduced from monotone iterative techniques, the classical Krasnoselski fixed point theorem or by application of recent fixed point theorems that combine both theories.

关键词： Dirichlet boundary value problem nonlocal perturbations Green's function parameter dependence

Control of chaotic oscillations of a satellite

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Applied Mathematics and Mechanics(English Edition) 2007年第7期28卷 893-900页

作者： Alexey Bobtsov nikolay Nikolaev Olga slita Department of Control systems and Informatics Saint-Petersburg State University of Information Technologies Mechanics and OpticsKronverksky Ave.49Saint-Petersburg197101Russia

Analytical conditions and practical methods of their realization are proposed to solve a problem of a command signal tracking for a nonlinear disturbed system. Nonlinear disturbed plants consisting of linear dynamic block and nonlinear block in feedback are considered. Nonlinear part of the plant and disturbance are unknown and bounded. The paper illustrates a possibility of applications of proposed algorithms to control libration angle of satellite.

关键词： adaptive control chaotic behaviour satellite control nonlinear stabilization nonlinear control output control

Mechanisms of cast structure and stressed state formation in Hadfield steel

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China Foundry 2016年第6期13卷 433-442页

作者： Dmitri Gorlenko Konstantin Vdovin nikolay Feoktistov Nosov Magnitogorsk state Technical University Magnitogorsk Russia

The paper describes the investigation of mechanisms of cast structure formation in Hadfield steel depending on the changes in the cooling rate of a casting in the following two temperature ranges： crystallization temperature（1,200-1,390 ℃） and the temperature of excessive phase separation（560-790 ℃）. Changes in the cooling rate of the crystallization temperature range from 1.1 to 25.0 ℃s^-1 result in the reduction of the average size of austenite grains from 266 to 131 μm. At the same time, the magnitude of developing shrinkage stresses changes from ＋195 to 0 MPa. When the cooling rate is higher than 16 ℃^-1, no shrinkage stresses are formed in the casting. Changes in the cooling rate of the casting in the temperature range of the excessive phase separation influence the number of phases, their morphology and chemical composition, the values of phase stresses, and the possibility of martensitic transformation. Changing in the cooling rate from 0.24 to 5.46 ℃^-1 results in the decrease of the amount of the excessive phase from 14.8% to 2.1%, which is composed of eutectic and carbides depending on the cooling rate, their quantitative ratio and morphology change. such changes in the microstructure are reflected on the changes of value of developing phase stresses. When the cooling rate is 0.24 ℃^-1, it is ＋100 MPa, while the increase of the cooling rate to 1.4 ℃^-1 results in the decrease of tensile stresses to 0 MPa and their qualitative stresses change to compressive ones. Further increase of the cooling rate results in the increase of the value of compressive stresses. When the cooling rate is 5.5 ℃^-1, their value reaches-92 MPa. Martensite forming in the structure of Hadfield steel is possible if the cooling rate of the casting in the range of excessive phase separation is less than 0.25 ℃^-1.

关键词： Hadfield steel crystallization austenite excessive phase stress