检索结果-南通市图书馆

Predicting impact strength of perforated targets using artificial neural networks trained on FEM-generated datasets

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第2期32卷 32-44页

作者： Nikita Kazarinov aleksandr Khvorov Saint Petersburg State University Saint Petersburg 199034Russia Higher School of Economics Saint Petersburg 190121Russia

The paper considers application of artificial neural networks(ANNs)for fast numerical evaluation of a residual impactor velocity for a family of perforated PMMA(Polymethylmethacrylate)*** ANN models were trained using sets of numerical results on impact of PMMA plates obtained via dynamic FEM coupled with incubation time fracture *** developed approach makes it possible to evaluate the impact strength of a particular target configuration without complicated FEM calculations which require considerable computational ***,it is shown that the ANN models are able to predict results for the configurations which cannot be processed using the developed FEM routine due to numerical instabilities and errors:the trained neural network uses information from successful computations to obtain results for the problematic cases.A simple static problem of a perforated plate deformation is discussed prior to the impact problem and preferable ANN architectures are presented for both *** insight into the perforation pattern optimization using a genetic algorithm coupled with the ANN is also made and optimized perforation patterns which theoretically enhance the target impact strength are constructed.

关键词： Machine learning Impact Dynamic fracture FEM Mesh distortion Optimization

Do non-dipole geomagnetic field behaviors persistently exist in the subarctic Pacific Ocean over the past 140 ka?

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2020年第18期65卷 1505-1507,M0003页

作者： Yi Zhong Yanguang Liu Xiaoqiang Yang Jian Zhang Jiabo Liu aleksandr bosin Sergey A.Gorbarenko Xuefa Shi Ting Chen Yu-Min Chou Wei Liu Haosen Wang Congcong Gai Jianxing Liu Alexander NDerkachev Xiaoke Qiang Qingsong Liu Centre for Marine Magnetism Department of Ocean Science and EngineeringSouthern University of Science and TechnologyShenzhen 518055China Key Laboratory of Marine Sedimentology and Metallogeny First Institute of OceanographyMinistry of Natural ResoursesQingdao 266061China Laboratory for Marine Geology Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266061China Department of Earth Science Sun Yat-sen UniversityGuangzhou 510275China Key Laboratory of Computational Geodynamics University of Chinese Academy of SciencesBeijing 100049China V.I.Il'ichev Pacific Oceanological Institute Far East Branch of Russian Academy of ScienceVladivostok 690041Russia State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Research School of Earth Sciences Australian National UniversityCanberra ACT 2601Australia State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of SciencesXi'an 710061China

Paleomagnetic records from globally distributed locations are essential for fully understanding geomagnetic field variations,particularly non-dipole field fluctuations[1].Paleomagnetic studies on historical time scales have demonstrated the existence of persistent geomagnetic flux patches,such as the Canadian(North America)and Siberian(East Asia)flux lobes,which may result from an organizing structure imposed on the geomagnetic field by lower mantle heterogeneity[2].Holocene paleomagnetic secular variations,reconstructed from the Alaskan margin of the Subarctic Pacific Ocean(SPO)[3]and revealed by dynamo modeling[4],further suggest that time-varying flux expulsions on the core-mantle boundary recurrently occur in high-latitude locations(***).

关键词： geomagnetic mantle Holocene

Experimental Study of Liquid Metal Flow for the Development of a Contact-Less Control Technique

在线全文

学校读者我要写书评

暂无评论

Fluid Dynamics & Materials Processing 2024年第7期20卷 1553-1564页

作者： aleksandr Poluyanov Ilya Kolesnichenko Laboratory of Technological Hydrodynamics Institute of Continuous Media Mechanics of the Ural Branch of Russian Academy of Science(ICMM UB RAS)Perm614018Russia

The article presents an experimental study on the flow of an eutectic gallium alloy in a cylindrical cell,which is placed in an alternating magnetic *** magnetic field is generated by a coil connected to an alternating current *** coil is located at a fixed height in such a way that its plane is perpendicular to the gravity vector,which in turn is parallel to the axis of the *** position of the cylinder can vary in height with respect to the *** forced flow of the considered electrically conductive liquid is generated due to the action of the localized electromagnetic *** is assumed that under the action of the alternating magnetic field,the liquid is heated uniformly,and the resulting heat is quickly absorbed by the forced flow,so that liquid free convection can be *** experiment is carried out using an ultrasonic Doppler *** transducer is installed in the axially located cylinder sluice and the other transducer is placed in the near-wall *** to the results,a velocity profile,corresponding to a two-tori flow pattern can be hardly obtained in the low frequency range of the power ***,this is possible in the high frequency *** average velocity profiles depend essentially on the location of the coil relative to the *** spectral analysis of velocity signals shows that the amplitude of the velocity pulsations is comparable to the average value of the flow *** experimental results and their verification through comparison with numerical calculations are intended to support the development of new methods for reducing the intensity of vortex flows during the electromagnetic separation of impurities through an electromagnetic induction mechanism(able to produce an electromotive force that displaces particles).

关键词： Ultrasonic doppler velocimeter electrically conductive medium azimuthal pinch experiment in liquid metal magnetohydrodynamics

A critical review on solid-state welding of high entropy alloys-processing,microstructural characteristics and mechanical properties of joints

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第4期34卷 78-133页

作者： Tushar Sonar Mikhail Ivanov Evgeny Trofimov aleksandr Tingaev Ilsiya Suleymanova Department of Welding Engineering Institution of Engineering and TechnologySouth Ural State University(National Research University)Chelyabinsk454080Russia Department of Materials Science Physical and Chemical Properties of MaterialsInstitution of Engineering and TechnologySouth Ural State University(National Research University)Chelyabinsk454080Russia

The high entropy alloys(HEAs)are the newly developed high-performance materials that have gained significant importance in defence,nuclear and aerospace sector due to their superior mechanical properties,heat resistance,high temperature strength and corrosion *** alloys are manufactured by the equal mixing or larger proportions of five or more alloying *** exhibit superior mechanical performance compared to traditional engineering alloys because of the extensive alloying composition and higher entropy of *** state welding(SSW)techniques such as friction stir welding(FSW),rotary friction welding(RFW),diffusion bonding(DB)and explosive welding(EW)have been efficiently deployed for improving the microstructural integrity and mechanical properties of welded HEA *** HEA interlayers revealed greater potential in supressing the formation of deleterious intermetallic phases and maximizing the mechanical properties of HEAs *** similar and dissimilar joining of HEAs has been manifested to be viable for HEA systems which further expands their industrial ***,the main objective of this review paper is to present a critical review of current state of research,challenges and opportunities and main directions in SSW of HEAs mainly CoCrFeNiMn and Al_xCoCrFeNi *** state of the art of problems,progress and future outlook in SSW of HEAs are critically reviewed by considering the formation of phases,microstructural evolution and mechanical properties of HEAs joints.

关键词： High entropy alloys Solid state welding Microstructure Mechanical properties

Microwave diagnostics of pulsed atmospheric discharge with electrolytic electrode and long-lived luminous formation in its afterglow

在线全文

学校读者我要写书评

暂无评论

High Voltage 2024年第1期9卷 127-136页

作者： Shixin Zhao Xingbao Lyu aleksandr Astafiev Chengxun Yuan Lin Miao Jingfeng Yao Ying Wang Anatoly Kudryavtsev aleksandr Chirtsov Gennadii Shabanov Zhongxiang Zhou School of Physics Harbin Institute of TechnologyHarbinChina Physics Department Saint Petersburg Electrotechnical University“LETI”St.PetersburgRussia Heilongjiang Provincial Key Laboratory of Plasma Physics and Application Technology HarbinChina Physics Department St.Petersburg State UniversitySt.PetersburgRussia Konstantinov Petersburg Nuclear Physics Institute National Research Centre“Kurchatov Institute”GatchinaRussia

The Gatchina discharge phenomenon holds significant promise as a laboratory model for simulating ball ***,crucial aspects concerning the plasma components of the resulting afterglow remain ***,the measurement of the electron density,a critical parameter,has not been fully achieved thus *** this study,microwave diagnostics and video recording were employed during a pulsed Gatchina discharge,along with synchronous measurement of discharge current and *** antennas were positioned at different heights to enable separate diagnosis of the discharge and the ensuing long-lived *** findings revealed that during the active phase of the Gatchina discharge,the plasma density was substantial enough to cause reflection of an electromagnetic wave with a frequency of 20 GHz from this highly conductive *** the afterglow,the signal experienced only a moderate weakening of 10–20 percent,facilitating the determination of the time dependence of average electron density during the afterglow's passage between the two *** measurements verified the unusually slow plasma decay in the afterglow of the Gatchina discharge,suggesting the potential significance of chemi-ionisation processes involving long-lived(metastable)particles.

关键词： holds luminous electrolytic

Comparing the Structural Parameters of the Milky Way to Other Spiral Galaxies

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第3期24卷 10-28页

作者： Jacob A.Guerrette aleksandr V.Mosenkov Dallin Spencer Zacory D.Shakespear Department of Physics and AstronomyN283 ESCBrigham Young University ProvoUT 84602USA

The structural parameters of a galaxy can be used to gain insight into its formation and evolution *** this paper,we strive to compare the Milky Way’s structural parameters to other,primarily edge-on,spiral galaxies in order to determine how our Galaxy measures up to the Local *** our comparison,we use the galaxy structural parameters gathered from a variety of literature sources in the optical and near-infrared wave *** compare the scale length,scale height,and disk flatness for both the thin and thick disks,the thick-to-thin disk mass ratio,the bulge-to-total luminosity ratio,and the mean pitch angle of the Milky Way’s spiral arms to those in other *** conclude that many of the Milky Way’s structural parameters are largely ordinary and typical of spiral galaxies in the Local Universe,though the Galaxy’s thick disk appears to be appreciably thinner and less extended than expected from zoom-in cosmological simulations of Milky Way-mass galaxies with a significant contribution of galaxy mergers involving satellite galaxies.

关键词： Galaxy disk-galaxies fundamental parameters-Galaxy structure

Agglomeration of coal and polyethylene mixtures during fixed‑bed co‑gasification

在线全文

学校读者我要写书评

暂无评论

International Journal of Coal Science & Technology 2024年第2期11卷 91-100页

作者： Igor G.Donskoy aleksandr N.Kozlov Maksim V.Penzik Denis A.Svishchev Lu Ding Melentiev Energy Systems Institute Russian Federation130 Lermontova StreetIrkutskRussia 664033 East China University of Science and Technology 130 Meilong RoadShanghai 200237China

The article presents the results of experimental studies on the gasification of mixtures of brown coal and polyethylene(up to 20 wt%fraction)in a laboratory *** work aims to study the agglomeration process during the heating and oxidation of the *** measurement results(gas composition,pressure drop)provide indirect information on the dynamics of thermal decomposition and structural changes in the fuel *** have shown that the interaction between polyethylene and a coal surface leads to the formation of dense agglomerates,in which the molten polymer acts as a *** form as a result of interfacial interactions between components and filtration flow *** hydrogen/carbon ratio in the solid residue of coal-polyethylene co-gasification increases from 0.07–0.2 to 1.11,indicating the formation of stable hydrocarbon compounds on the carbon *** conducted research makes it possible to identify possible interactions between chemical reactions and transfer processes that lead to agglomeration in mixtures of coal with polyethylene.

关键词： Coal Polyethylene Gasification Combustion Agglomeration

Pulsed THz radiation under ultrafast optical discharge of vacuum photodiode

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Optoelectronics 2024年第2期17卷 99-112页

作者： aleksandr Ushakov Kseniia Mamaeva Leonid Seleznev Georgy Rizaev Vladimir Bukin Timophey Dolmatov Pavel Chizhov Vladimir Bagdasarov Sergey Garnov Prokhorov General Physics Institute of the Russian Academy of Sciences Moscow 119991Russia Physical Institute Russian Academy of SciencesMoscow 119991Russia Moscow Institute of Physics and Technology Dolgoprudny 141700Russia Russian Institute for Scientific and Technical Information Moscow 125190Russia

In this paper,we first present an experimental demonstration of terahertz radiation pulse generation with energy up to 5 pJ under the electron emission during ultrafast optical discharge of a vacuum *** use a femtosecond optical excitation of metallic copper photocathode for the generation of ultrashort electron bunch and up to 45 kV/cm external electric field for the photo-emitted electron *** of terahertz pulses energy as a function of emitted charge density,incidence angle of optical radiation and applied electric field have been *** and polarization characteristics of generated terahertz pulses have also been *** proposed semi-analytical model and simulations in COMSOL Multiphysics prove the experimental data and allow for the optimization of experimental conditions aimed at flexible control of radiation parameters.

关键词： Electron emission Vacuum photodiode Ultrafast excitation Terahertz

Interaction of edge dislocations with voids in tungsten

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Tungsten 2024年第3期6卷 633-646页

作者： Arseny Kazakov Rita I.Babicheva aleksandr Zinovev Dmitry Terentyev Kun Zhou Elena A.Korznikova Sergey V.Dmitriev Research Laboratory for Metals and Alloys under Extreme Impacts Ufa University of Science and Technology Institute for Metals Superplasticity Problems of RAS School of Mechanical and Aerospace Engineering Nanyang Technological University Institute for Nuclear Energy Technology Belgian Nuclear Research Center Technological Machines and Equipment Department Ufa State Petroleum Technological University Institute of Mechanical Science Problems of RAS Institute of Molecule and Crystal Physics UFRC of Russian Academy of Sciences

Tungsten is widely used as a material capable of withstanding extreme operating conditions and is one of the candidates for use in fusion and Generation Ⅳ fission *** modelling implemented to solve various material science problems is an indispensable approach for improving material *** work analyzes the interaction of an edge dislocation with a void in single-crystal tungsten with the help of molecular dynamics *** different approaches for studying the dynamics of dislocations in tungsten that differ in boundary conditions are *** interactions of the dislocation and void at different temperatures are investigated,and based on the obtained stress-strain curves,the dislocation obstacle strength for voids having various diameters is *** is shown that when applied to a crystal with small voids,the model with the fixed boundary conditions returns incorrect ***,the influence of the cell size for the model with periodic boundary conditions is analyzed,and the case of a non-central interaction of a dislocation with a void is *** obtained results improve our understanding of the mechanical response of irradiated materials.

关键词： Tungsten Molecular dynamics method Dislocations Voids Boundary conditions