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Consideration of the influence of supports in modeling the electromagnetic fields of 25 kV traction networks under emergency conditions

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Global Energy interconnection 2024年第4期7卷 528-540页

作者： Konstantin Suslov Andrey Kryukov Ekaterina Voronina Pavel ilyushin Department of Hydropower and Renewable Energy National Research UniversityMoscow Power Engineering InstituteMoscow 11250Russia Department of Power Supply and Electrical Engineering Irkutsk National Research Technical UniversityIrkutsk 664074Russia Department of Transport Electric Power Irkutsk State Transport UniversityIrkutsk 664074Russia Department of Research on the Relationship between Energy and the Economy Energy Research Institute of the Russian Academy of SciencesMoscow 117186Russia

Single-phase 25 kV traction networks of electrified alternating current(AC)railways create electromagnetic fields(EMFs)with significant levels of *** most intense magnetic fields occur when short circuits exist between the contact wire and rails or *** the short duration of exposure,they can adversely affect electronic devices and induce significant voltages in adjacent power lines,which is dangerous for operating *** numerous investigations have focused on modeling the EMF of traction networks and power lines,the challenge of determining the three-dimensional electromagnetic fields near metal supports during the flow of a short-circuit current through them is yet to be *** this case,the field has a complex spatial structure that significantly complicates the calculations of *** study proposes a methodology,algorithms,software,and digital models for determining the EMF in the described emergency *** the modeling process,the objects being studied were represented by segments of thin wires to analyze the distribution of the electric charge and calculate the intensities of the electric and magnetic *** approach was implemented in the Fazonord software,and the modeling results show a substantial increase in EMF levels close to the support,with a noticeable decrease in the levels as the distance from it *** procedure implemented in the commercial software Fazonord is universal and can be used to determine electromagnetic fields at any electrical power facility that includes live parts of limited *** on the proposed procedure,the EMF near the supports of overhead power lines and traction networks of various designs could be determined,the EMF levels at substations can be calculated,and the influence of metal structures located near traction networks,such as pedestrian crossings at railway stations,can be considered.

关键词： Power supply systems AC railways Emergency conditions Electromagnetic fields near supports Modeling Electromagnetic safety

Phase composition,conductivity,and sensor properties of cerium-doped indium oxide

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Nano Materials Science 2024年第2期6卷 193-200页

作者： M.i.ikim G.N.gerasimov V.F.Gromov O.J.ilegbusi L.i.Trakhtenberg N.N.Semenov Federal Research Center for Chemical Physics of RAS MoscowRussia University of Central Florida OrlandoFLUSA Moscow institute of Physics and Technology(State University) DolgoprudnyMoscow RegionRussia Lomonosov Moscow State University MoscowRussia

The hydrothermal synthesis of in_(2)O_(3)and CeO_(2)–in_(2)O_(3)is investigated as well as the properties of sensor layers based on these *** the synthesis of in_(2)O_(3),intermediate products in(OH)_(3)and inOOH are formed,which are the precursors of stable cubic(c-in_(2)O_(3))and metastable rhombohedral(rh-in_(2)O_(3))phases,respectively.A transition from c-in_(2)O_(3)to rh-in_(2)O_(3)is observed with the addition of CeO_(2).The introduction of cerium into rh-in_(2)O_(3)results in a decrease in the sensor response to hydrogen,while it increases in composites based on c-in_(2)O_(3).The data on the sensor activity of the composites correlate with XPS results in which CeO_(2)causes a decrease in the concentrations of chemisorbed oxygen and oxygen vacancies in rh-in_(2)O_(3).The reverse situation is observed in composites based on c-in_(2)O_(3).Compared to in_(2)O_(3)and CeO_(2)–in_(2)O_(3)obtained by other methods,the synthesized composites demonstrate maximum response to H_(2)at low temperatures by 70–100℃,and have short response time(0.2–0.5 s),short recovery time(6–7 s),and long-term stability.A model is proposed for the dependence of sensitivity on the direction of electron transfer between in_(2)O_(3)and CeO_(2).

关键词： Cerium oxide indium oxide Nanocomposite Hydrothermal method Cubic phase Rhombohedral phase Sensor response Conductivity Hydrogen Response/recovery time

Flash Lamps as ignition and initiation Sources of the VS-2 Pyrotechnic Composition

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含能材料 2022年第4期30卷 370-378页

作者： sergey i.gerasimov.mikhail a.ilyushin sergey M.Putis sergey A.Dushenok irina V.Shugalei Andrey M.Sudarikov Russian Federal Nuclear Center‑All‑Russian Research institute of Experimental Physics SarovRussia Sarov institute of Physics and Technology is a Branch of the Scientific Research Nuclear University MEPhi SarovRussia Nizhny Novgorod State Technical University Named after R.E.Alekseev Nizhny NovgorodRussia RAS institute for Studying Problems in Mechanical Engineering ‑is a Branch of the RAS Applied Physics InstituteNizhny NovgorodRussia "Technologist"Special Design and Technological Bureau St.PetersburgRussia Saint‑Petersburg State institute of Technology(Technical University) St.PetersburgRussia Russian State Hydro‑meteorological University St.PetersburgRussia

in the present work it is found that the pyrotechnic composition VS⁃2 can be initiated with flash lamps iFC⁃500 and ***⁃2 pyrotechnic composition contains 90%of mercury(Ⅱ)5⁃hydrazinotetrazolate perchlorate and 10%of optically trans⁃parent copolymer of 2⁃methyl⁃5⁃vinyltetrazole and methacrylic acid(PVMT).We have found that the flash lamps make it possi⁃ble to initiate combustion of VS⁃2 composition with its transition to detonation both in cylindrical charges placed in brass caps of 5 mm diameter and 2 mm high,and film charges with 10 mm×80 mm in size and surface weights of 60 mg·cm^(-2)and 90 mg·cm^(-2),showing ignition delay times 10μs and 3μs,*** also measured detonation velocities for VS⁃2 composition film charges,which were 4375-4505 m·s^(-1)(of the charge being surface mass 60 mg·cm^(-2))and 4221-4281 m·s^(-1)(of the charge be⁃ing surface mass 90 mg·cm^(-2))and their blasting action on the aluminum *** depths of the normal shock wave imprints at the charge⁃barrier interface were 0.6-0.7 mm(for surface mass of the film charges 60 mg·cm^(-2))and 1.2-1.3 mm(for surface mass of the film charges 90 mg·cm^(-2))

关键词： VS⁃2 pyrotechnic composition flash lamps ignition transition of combustion to detonation blasting action

An application of space-filling curves to improve results of turbulent aerodynamics modeling with convolutional neural networks

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Chinese Journal of Aeronautics 2024年第2期37卷 81-92页

作者： mikhail PETROV Sofia ZiMiNA Moscow institute of Physics&Technology Dolgoprudny 141701Russia

When carrying out calculations for turbulent flow simulation,one inevitably has to face the choice between accuracy and speed of *** order to simultaneously obtain both a computationally efficient and more accurate model,a surrogate model can be built on the basis of some fast special model and knowledge of previous calculations obtained by more accurate base models from various test bases or some results of serial *** objective of this work is to construct a surrogate model which allows to improve the accuracy of turbulent calculations obtained by a special model on unstructured *** this purpose,we use 1D Convolutional Neural Network(CNN)of the encoder-decoder architecture and reduce the problem to a single dimension by applying space-filling *** an approach would have the benefit of being applicable to solutions obtained on unstructured *** this work,a non-local approach is applied where entire flow fields obtained by the special and base models are used as input and ground truth output ***-Allmaras(SA)model and Near-wall Domain Decomposition(NDD)method for SA are taken as the base and special models *** efficiency and accuracy of the obtained surrogate model are demonstrated in a case of supersonic flow over a compression corner with different values for angleαand Reynolds number *** conducted an investigation into interpolation and extrapolation by Re and also into interpolation byα.

关键词： Space-filling curves Convolutional neural network Domain decomposition Turbulent flows Unstructured mesh

Selection of shaped charges parameters for producing aluminum particles with velocities in the range of 2.5-16 km/s

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Defence Technology（防务技术） 2024年第8期38卷 126-135页

作者： Vladimir i.Kolpakov sergey V.Fedorov Ekaterina P.Vinogradova irina A.Bolotina Bauman Moscow State Technical University Moscow 105005Russia

Testing rocket and space technology objects in ground conditions for resistance to the impact of meteoroids and fragments of space debris can be carried out using shaped charges. To substantiate the design parameters of shaped charges that ensure the formation of aluminum particles in a wide velocity range(from 2.5 to 16 km/s), numerical modeling of the formation process was carried out within the framework of a two-dimensional axisymmetric problem of continuum mechanics using three different computing codes to increase the reliability of the results. The calculations consider shaped charges with a diameter of 20-100 mm with aluminum liners of various shapes. it is shown that the formation of particles with velocities close to the lower limit of the considered range is ensured by gently sloping segmental liners of degressive thickness. To form higher-velocity particles with velocities over 5 km/s, it is proposed to use combined liners, the jet-forming part of which has the shape of a hemisphere of constant thickness or the shape of a semi-ellipsoid or semi-superellipsoid of rotation of degressive thickness.

关键词： Space debris Meteoric impact Explosion Shaped charge High-velocity aluminum element Segmental liner Combined liner Numerical simulation

Reactivation of hepatitis B virus infection – an important aspect of multifaceted problem

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World Journal of Gastroenterology 2024年第26期30卷 3193-3197页

作者： sergey Morozov sergey Batskikh Department of Gastroenterology Hepatology and NutritionFederal Research Center of NutritionBiotechnology and Food SafetyMoscow 115446Russia Department of Hepatology Moscow Clinical Scientific Center N.A.A.S.LoginovMoscow 111123Russia

in this editorial we comment on the article published in the recent issue of the W orld Journal of *** focus specifically on the problem of occult hepatitis B virus(HBV)infection,that is a result of previous hepatitis B(PHB)and a source for reactivation of *** prevalence of PHB is underestimated due to the lack of population testing ***,this condition not only com-plicate anticancer treatment,but may be responsible for the development of other diseases,like cancer or autoimmune *** we unveil possible mecha-nisms responsible for realization of these processes and suggest practical approa-ches for diagnosis and treatment.

关键词： Occult hepatitis B virus infection Hepatitis B virus reactivation Previous hepatitis B Cancer Autoimmune disorders

Radiation of a TM mode from an open end of a three-layer dielectric capillary

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Chinese Physics B 2024年第7期33卷 311-318页

作者： sergey NGalyamin Alexandr MAltmark St.Petersburg State University 7/9Universitetskayanab.St.Petersburg 199034Russia St.Petersburg Electrotechnical University“LETi” 5ProfessoraPopovaSt.Petersburg 197022Russia

Modern trends in beam-driven radiation sources include the interaction of Cherenkov wakefields in open-ended circular waveguides with complicated dielectric linings, with a three-layer dielectric capillary recently proposed to reduce radiation divergence being a representative example [Opt. Lett. 45 5416(2020)]. We present a rigorous approach that allows for an analytical description of the electromagnetic processes that occur when the structure is excited by a single waveguide TM mode. in other words, the corresponding canonical waveguide diffraction problem is solved in a rigorous formulation. This is a continuation of our previous papers which considered simpler cases with a homogeneous or two-layer dielectric filling. Here we use the same analytical approach based on the Wiener–Hopf–Fock technique and deal with the more complicated case of a three-layer dielectric lining. Using the obtained rigorous solution, we discuss the possibility of manipulating the far-field radiation pattern using a third layer made of a low permittivity material.

关键词： diffraction radiation open-ended waveguide Wiener–Hopf technique Cherenkov radiation

A Note on Transition Kernels for the Most UnfavourableMixed Strategies of the Market

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Journal of the Operations Research Society of China 2024年第1期12卷 35-50页

作者： sergey N.Smirnov Faculty of Computational Mathematics and Cybernetics Lomonosov Moscow State UniversityMoscowRussian Federation 119991

We consider a deterministic model of market evolution with trading constraints andapply a game-theoretic approach to the superhedging *** obtain sufﬁcientconditions for the game equilibrium and prove under these conditions the existenceof a Borel-measurable transition kernel describing dependence on price prehistory ofthe most unfavourable mixed strategy of the market.

关键词： Superhedging Guaranteed deterministic approach Optimal mixedstrategies of the market Borel-measurable transition kernel Game equilibrium

Structural Stability of the Financial Market Model: Continuity of Superhedging Price and Model Approximation

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Journal of the Operations Research Society of China 2024年第1期12卷 215-241页

作者： sergey N.Smirnov Faculty of Computational Mathematics and Cybernetics Lomonosov Moscow State UniversityMoscow119991Russian Federation

The present paper continues the topic of our recent paper in the same journal,aiming to show the role of structural stability in financial *** the context of financial market modeling,structural stability means that a specific“no-arbitrage”property is unaffected by small(with respect to the Pompeiu–Hausdorff metric)perturbations of the model’s *** formulate,based on our economic interpretation,a new requirement concerning“no arbitrage”properties,which we call the“uncertainty principle”.This principle in the case of no-trading constraints is equivalent to structural *** demonstrate that structural stability is essential for a correct model approximation(which is used in our numerical method for superhedging price computation).We also show that structural stability is important for the continuity of superhedging prices and discuss the sufficient conditions for this continuity.

关键词： Uncertainty Structural stability No arbitrage Continuity of superhedging price Compact-valued multifunction Financial market model approximation Trading constraints