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Reduction of friction by normal *** of contact stiffness

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Friction 2017年第1期5卷 45-55页

作者： M.POPOv v.L.POPOv n.v.POPOv Berlin University of Technology Berlin 10623 GermanyTomsk Polytechnic University Tomsk 634050 RussiaTomsk State University Tomsk 634050 Russia Berlin University of Technology Berlin 10623 Germany

The present paper is devoted to a theoretical analysis of sliding friction under the influence of oscillations perpendicular to the sliding *** contrast to previous works we analyze the influence of the stiffness of the tribological contact in detail and also consider the case of large oscillation amplitudes at which the contact is lost during a part of the oscillation period,so that the sample starts to 'jump'.It is shown that the macroscopic coefficient of friction is a function of only two dimensionless parameters-a dimensionless sliding velocity and dimensionless oscillation *** function in turn depends on the shape of the contacting *** the present paper,analysis is carried out for two shapes:a flat cylindrical punch and a parabolic *** we consider 'stiff systems',where the contact stiffness is small compared with the stiffness of the *** role of the system stiffness will be studied in more detail in a separate paper.

关键词： sliding friction out-of-plane oscillation contact stiffness coefficient of friction active control of friction

The role of deformations and orientations in an alpha ternary fission of Thorium

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nuclear Science and Techniques 2022年第6期33卷 1-8页

作者： A.v.Mahesh Babu n.Sowmya H.C.Manjunatha n.Dhananjaya Department of Physics BMSIT&MAffiliated to VTUBangaloreKarnataka 560064India Department of Physics Government College for WomenKolarKarnataka 563101India

The alpha ternary fission half-lives of thorium isotopes have been studied using the Coulomb and proximity potential *** role of the deformation effects and the angle of orientation were included during the evaluation of the total *** combinations were identified using cold valley plots of the driving *** half-lives and yields were evaluated using the penetration *** dependence of the logarithmic half-lives on different angles of orientation was *** evaluated alpha ternary fission yield was compared with that of the available experiments with and without *** half-lives obtained in the present work were compared with those of the available *** alpha ternary fission fragments were identified in the isotopes of *** alpha ternary fission half-lives were compared to the binary fission *** binary fission half-lives are dominant in the ^(209-225)Th nuclei,and the ternary fission half-lives are dominant in the isotopes of the ^(226-238)Th nuclei.

关键词： Alpha ternary fission Yield Half-lives Driving potential

Transition from oceanic subduction to continental collision:Insights from volcanogenic-sedimentary rocks of the Tannuola terrane(northern Central Asian Orogenic Belt)

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Geoscience Frontiers 2024年第4期15卷 41-60页

作者： E.v.vetrov n.I.vetrova v.S.Sobolev Institute of Geology and Mineralogy SB RAS Koptyuga ave.3NovosibirskRussia

Magmatism associated with oceanic subduction plays a dominant role in crustal growth during the Earth's *** Tannuola terrane,situated in the northern Central Asian Orogenic Belt(CAOB),is a key area to understanding oceanic subduction and initial collision processes in the northern *** order to investigate the switch from subduction to collision settings,detailed field mapping,zircon SHRIMP U-Pb geochronological and whole-rock geochemical studies of volcanogenic-sedimentary rocks from the Tannuola terrane were carried *** U-Pb ages indicate multi-stage volcanism lasted at least 30 Ma from~540 to~510 Ma,that can be divided into three events:the late Ediacaran(before~540 Ma),the early Cambrian(~520 Ma)and the middle Cambrian(~510 Ma).These ages are inter-preted to the initial,main and final stages of oceanic subduction during the late Proterozoic-early *** the late Ediacaran,tholeiitic basalts with highεnd(t)values(from+7.4 to+8.5)were *** forming by the 10%-30%partial melting of spinel-garnet mantle source during slab *** the early Cambrian,transitional from tholeiitic to calc-alkaline basaltic rocks withεnd(t)value(+5.6)and coeval intermediate-felsic volcanic rocks with similarεnd(t)values(+5.9 and+6.5)*** early Cambrian basaltic rocks are interpreted to be derived by 10%-30%partial melt-ing of a depleted mantle source metasomatized by slab-derived fluids released from the subducting ocea-nic *** middle Cambrian calcalkaline basaltic rocks withεnd(t)value of+6.2 might be emplaced as a result of low(5%-10%)degree partial melting of a metasomatized mantle followed by fractional crys-tallization of clinopyroxene and *** intermediate-felsic volcanic rocks withεnd(t)values from+6.0 to+6.8 were formed through fractionation of the juvenile neoproterozoic *** middle Cambrian volcanism is interpreted to be triggered by the slab break-off during the transition to a collisional se

关键词： Island-arc magmatism Ediacaran Cambrian zircon U-Pb dating nd isotopes Central asian orogenic belt

Analysis of global momentum transfer due to buried mine detonation

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Defence Technology（防务技术） 2019年第5期15卷 821-827页

作者： n.Heider v.Denefeld H.Aurich Ernst-Mach-Institute

The emergence of improvised explosive devices (IED) significantly extended the spectrum of possiblethreat mechanisms to military vehicles and their occupants. Especially buried high explosive (HE)charges lead to new and originally not investigated loading conditions during their detonation. It is theinteraction of the embedding geomaterial with the detonation products that leads to a strongly increasedglobal impulse transfer on the vehicle with following high accelerations on the vehicle occupant. Thispaper presents a comprehensive approach for the analysis of occupant loading. In a first step, we presentthe so called ring technology which allows the experimental determination of the locally resolvedspecific impulse distribution on a vehicle floor due to buried charge detonation. A complementarymethod is the use of scaled model vehicles that allows the determination of global vehicle loading parameterssuch as jump height or vehicle accelerations. Both techniques were used to study the influenceof burial conditions as burial depth, embedding material or water content on the impulse transfer ontothe vehicle. These experimental data are used to validate material models for the embedding sand orgravel materials. This validated material description is the basis for numerical simulation models used inthe assessment of occupant safety. In the last step, we present a simulation model for a generic militaryvehicle including a Hybrid III occupant dummy that is used for the determination of biomechanicaloccupant exposure levels. Typical occupant loadings are evaluated and correlated with burial conditionsas HE mass and global momentum transfer.

关键词： Improvised explosive device vehicle protection Occupant loading

Joint effect of quasicrystalline icosahedral and L1_(2)-strucutred phases precipitation on the grain structure and mechanical properties of aluminum-based alloys

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Journal of Materials Science & Technology 2021年第28期87卷 196-206页

作者： A.G.Mochugovskiy n.Yu.Tabachkova M.Esmaeili Ghayoumabadi v.v.Cheverikin A.v.Mikhaylovskaya national University of Sciences and Technology“MISIS” 119049Leninskiy Ave.4MoscowRussia Prokhorov General Physics Institute of the Russian Academy of Sciences MoscowRussia

Dispersoid hardening is a key factor in increasing the recrystallization resistance and mechanical strength of non-heat treatable aluminum-based *** and Zr are the main elements that form dispersoids in commercial Al-based *** this work,the annealing-induced precipitation behavior,the grain structure,and the mechanical properties of Al-3.0 Mg-1.1 Mn and Al-3.0 Mg-1.1 Mn-0.25 Zr alloys were *** microstructure and the mechanical properties were significantly affected by annealing regimes after casting for both *** research demonstrated a possibility to form high-density distributed quasicrystalline-structured I-phase precipitates with a mean size of 29 nm during low-temperature annealing of as-cast *** manganese-bearing precipitates of I-phase increased recrystallization resistance and significantly enhanced the mechanical strength of the alloys *** estimated strengthening effect owing to I-phase precipitation was 150 *** to the formation of L1_(2)-structured Al3Zr dispersoids with a mean size of 5.7 nm,additional alloying with Zr increased yield strength by about 90 *** L1_(2)-phase strengthening effect was estimated through the dislocation bypass looping and shearing mechanisms.

关键词： Aluminum alloy Quasicrystals Dispersoid hardening Recrystallization Mechanical properties

Control strategy for seamless transition from islanded to interconnected operation mode of microgrids

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Journal of Modern Power Systems and Clean Energy 2017年第2期5卷 169-176页

作者： C.n.PAPADIMITRIOU v.A.KLEFTAKIS n.D.HATZIARGYRIOU Department of Electrical and Computer Engineering National Technical University of Athens(NTUA)AthensGreece

Microgrids can operate either interconnected to the utility grid or disconnected forming an island. The transition between these modes can cause transient overcurrents or power oscillations jeopardizing the equipment safety or the system stability. This paper proposes a local multi agent control method for a seamless transfer between the islanded and interconnected modes of operation with agents implemented into the microgrid central switch(MCS) and into the microsources inverters. The MCS agent supervises the grid status and controls the switch for the transition of the microgrid through the different operation modes, while it communicates locally with the inverter agents of the microsources. The inverter agents undertake the synchronization process in case of reconnecting and change the inverter control mode depending on the grid status. Simulation and experimental results are presented to show the performance and feasibility of the proposed strategy.

关键词： Microgrid Islanding Reconnection Agents Synchronization Control hardware-in-the-loop(CHIL)

Morphology of crater and caldera lakes in the Far Eastern region of Russia and the features of their development

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Journal of Mountain Science 2024年第4期21卷 1246-1258页

作者： Dmitrii n.KOZLOv Ekaterina v.LEBEDEvA Institute of Marine Geology and Geophysics Far Eastern Branch of the Russian Academy of SciencesYuzhno-Sakhalinsk 693022Russia Institute of Geography Russian Academy of SciencesMoscow 119017Russia

volcanic lakes in the Kuril-Kamchatka region are difficult to access,and for this reason,they remain poorly studied,with only scattered and brief data *** authors have conducted a study of 10 lake basins using modern digital echolocation survey techniques and have also compiled and summarized published data for 15 lakes in the region,calculating their main morphometric *** has been established that many caldera lake basins are modified by young explosive funnels,extrusive or effusive domes,and exhibit traces of hydrothermal *** lakes of the same genetic type in the Kuril-Kamchatka region are similar in depth and depression forms,the group of caldera lakes shows less homogeneity across all morphometric *** was found that the absolute heights of the reservoirs on Kamchatka Peninsula are generally greater than those on the Kuril Islands,as is often the case with the size of their *** volcanic lakes under study can rapidly change their volume and shape under the influence of endogenous *** the first time for this region,on the base of repeated observations,underwater extrusive dome rate growth and the approximate rates of 2 lake level changes were *** observations of lakes in the Ksudach calderas(Kamchatka)and on Simushir Island indicate approximate rates of level changes:a decrease ranging within 0.5-0.6 m per year(over a 27-year observation interval)and an increase reaching up to 0.26 m per year(over a 48-year interval).The growth rate of the underwater extrusive dome in Lake Shtyubel has averaged 1-1.6 m per year over the past 25 *** analysis has facilitated the first generalization regarding the morphology and developmental features of crater and caldera lakes in the Kuril-Kamchatka region of Russia,representing an important step in their *** results obtained will provide a solid foundation for subsequent research in this region and may be of interest to researchers studying

关键词： volcanic lakes Echolocation survey volcanism Gashydrotherms Kamchatka Kuril Islands

nOn-STATIOnARY EFFECTS In HYPERSOnIC nOnUnIFORM DUSTY-GAS FLOW PAST A BLUnT BODY

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Acta Mechanica Sinica 1999年第3期15卷 201-214页

作者： A.n.Osiptsov A.v.Rozin 王柏懿 Institute of Mechanics Lomonosov Moscow State University119899 MoscowRussia Institute of Mechanics Chinese Academy of SciencesBeijing 100080China

In the framework of the two-fluid model, a hypersonic flow of a nonuniform dusty gas with low inertial (non-depositing) particles around a blunt body is considered. The particle mass concentration is assumed to be small, so that the effect of particles on the carrier phase is significant only inside the boundary layer where the particles accumulate. Stepshaped and harmonic nonuniformities of the particle concentration ahead of the bow shock wave are considered and the corresponding nonstationary distributions of the particle concentration in the shock layer are studied. On the basis of numerical study of nonstationary two-phase boundary layer equations derived by the matched asymptotic expansion method, the effects of free-stream particle concentration nonuniformities on the thermal flux, and the friction coefficient in the neighborhood of stagnation point are investigated, in particular, the most “dangerous” nonuniformity periods are found.

关键词： dusty gas hypersonic flow blunt body non-stationary effects

Conformally symmetric wormhole solutions supported by non-commutative geometry in f(Q,T)gravity

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Communications in Theoretical Physics 2024年第2期76卷 111-124页

作者： Chaitra Chooda Chalavadi v venkatesha n S Kavya S v Divya Rashmi Department of P.G.Studies and Research in Mathematics Kuvempu UniversityShankaraghattaShivamogga 577451KarnatakaIndia Department of Mathematics Vidyavardhaka College of EngineeringMysuru—570002India

This paper investigates wormhole solutions within the framework of extended symmetric teleparallel gravity,incorporating non-commutative geometry,and conformal *** achieve this,we examine the linear wormhole model with anisotropic fluid under Gaussian and Lorentzian *** primary objective is to derive wormhole solutions while considering the influence of the shape function on model parameters under Gaussian and Lorentzian *** resulting shape function satisfies all the necessary conditions for a traversable ***,we analyze the characteristics of the energy conditions and provide a detailed graphical discussion of the matter contents via energy ***,we explore the effect of anisotropy under Gaussian and Lorentzian ***,we present our conclusions based on the obtained results.

关键词： traversable wormhole f(Q T)gravity energy conditions non-commutative geometry conformal motion