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Basic features of the multiscale interaction between tearing modes and slab ion-temperature-gradient modes

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Chinese Physics B 2019年第12期28卷 237-247页

作者： L Wei Z x Wang J q Li Z q Hu Y Kishimoto Key Laboratory of Materials Modification by Laser Ionand Electron Beams(Ministry of Education)School of PhysicsDalian University of TechnologyDalian 116024China Southwestern Institute of Physics Chengdu 610041China Graduate School of Energy Science Kyoto UniversityGokashoUjiKyoto 1-0011Japan

Nonlinear interaction between tearing modes(TM) and slab ion-temperature-gradient(ITG) modes is numerically investigated by using a Landau fluid model. It is observed that the energy spectra with respect to wavenumbers become broader during the transition phase from the ITG-dominated stage to TM-dominated stage. Accompanied with the fast growth of the magnetic island, the frequency of TM/ITG with long/short wavelength fluctuations in the electron/ion diamagnetic direction decreases/increases respectively. The decrease of TM frequency is identified to result from the effect of the profile flattening in the vicinity of the magnetic island, while the increase of the frequencies of ITG fluctuations is due to the eigenmode transition of ITG induced by the large scale zonal flow and zonal current related to TM. Roles of zonal current induced by the ITG fluctuations in the instability of TM are also analyzed. Finally, the electromagnetic transport features in the vicinity of the magnetic island are discussed.

关键词： magnetic reconnection tearing modes magnetohydrodynamics drift waves nonlinear phenomena

ON THE BURN RESISTANCE OF Ti-35V-15Cr-0.05C TITANIUM ALLOY

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Acta Metallurgica Sinica(English Letters) 1998年第3期11卷 202-206页

作者： G.P.Li d.Li Y.Y.Liu q.J.Wang S.x.Guan q.C.Li Inst of Metal Research The Chinese Acad of Sciences Shenyang China

The Ti-35V-15Cr-0.05C (wt% is a new nonburning titanium alloy. The test for alloy combustibility was carried out by using CO2 laser. A 430 watt and 6mm diameter laser spot impinges directly on the sample within normal atmospheric pressure and temperature. The results show that the ignition time of the nonburning titanium alloy is the longest in the eight examined titanium alloys, and is 3.5 times that of TC4 alloy. The ignition tempeerature of the nonburning alloy is 2991° C, and is higher than that of TC4 alloy by 1976°C. On the condition of high tempeerature and rich oxygen,the surface of alloy forms a melting layer which plays roles of oxygen insulation, heat insulation and burning products insulation. This is the mechanism of combustion resistance.

关键词： Ti-35V-15Cr-0.05C (wt%) nonburning titanium alloy combustion resistance

Amino Compounds in Poultry Litter,Litter-Amended Pasture Soils and Grass Shoots

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Pedosphere 2014年第2期24卷 178-185页

作者： Z.q.HE Z.N.SENWO H.x.ZOU I.A.TAZISONG d.A.MARTENS USdA-ARS Southern Regional Research Center department of Biological and Environmental Sciences Alabama A&M University department of Chemical and Biological Engineering the University of Maine USdA-ARS Southwest Watershed Research Center

Amino compounds （ACs）, i.e., amino acids and amino sugars, are the major forms of organic nitrogen （N） in animal manure and soil. To increase our understanding on the effect of long-term poultry litter （PL） application on soil AC pools and turnover, in this study, we determined the contents of 21 ACs in 23 PL samples, i5 soil samples collected from 0-20, 20-40, and 40-60 cm layers of five pasture plots with 0, 5, 10, 15 and 20 years of PL applications, and 5 grass shoot samples grown on these pasture fields. The contents of 21 ACs were simultaneously determined by methanesulfonic acid hydrolysis/extraction and anion chromatography-pulsed amperometry. PL application increased soil total and individual AC contents with a distribution pattern similar to that of AC in PL. The highest AC-N concentrations were observed in the soils with 10- or 15-year PL applications, inconsistent with the order of annual application rates or eunmlative applied PL amounts. Application of PL increased the AC contents in grass shoots whereby the highest increase of most ACs was with the shoots from the fields that received PL for 5 years. These observations suggested that both freshly applied and residual PL had contributions to the soil AC-N, and that PL application also accelerated AC-N transformation in soil.

关键词： amino acids amino sugars broiler feed soil nitrogen

Effect of grain size on fatigue cracking at twin boundaries in a CoCrFeMnNi high-entropy alloy

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Journal of Materials Science & Technology 2020年第4期39卷 1-6页

作者： A.G.Wang x.H.An J.Gu x.G.Wang L.L.Li W.L.Li M.Song q.q.duan Z.F.Zhang x.Z.Liao School of Aerospace Mechanical&Mechatronic EngineeringThe University of Sydne0ySydneyAustralia State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Materials Fatigue and Fracture division Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Max-Planck-Institut für Eisenforschung Max-Planck-Stra?e 140237 DüsseldorfGermany

The fatigue cracking behavior at twin boundaries(TBs)in a Co Cr Fe Mn Ni high-entropy alloy with three different grain sizes was systematically investigated under low-cycle *** of grain size,the change from slip band cracking to TB cracking occurred with increasing the difference in the Schmid factors(dSF)between matrix and ***,the required critical dSF for the transition of the dominant cracking mode decreases with decreasing grain size due to the reduced slip band spacing that increases the impingement sites on the TBs and facilitates the coalescence of defects and voids to initiate TB cracks.

关键词： High-entropy alloy Fatigue cracking Twin boundary Slip band Grain size

NUMERICAL SIMULATION OF ExTRUSION OF COMPOSITE POWdERS PREPAREd BY HIGH ENERGY MILLING

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Acta Metallurgica Sinica(English Letters) 2004年第1期17卷 51-54页

作者： x.q.Li W.P.Chen W.xia q.L.Zhu Y.Y.Li E.d.Wang College of Mechanical Engineering South China University of Technology.Guangzhou 510640 China School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China

Based on the characteristic of high energy milling and the micromechanics of composite material, a plastic constitutive equation is implemented for milled composite powders. To check the equation, the extrusion of Ti/Al composite powders prepared by high energy milling was simulated. It was from the numerical analysis that the predicted extrusion pressure mounted up with milling time and extrusion ratio increasing, which was perfect agreement with experimental results.

关键词： high energy milling composite powder plastic constitutive equation extrusion numerical simulation

On the texture evolution of Mg-Zn-Ca alloy with different hot rolling paths

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Journal of Magnesium and Alloys 2017年第2期5卷 166-172页

作者： q.Li G.J.Huang x.d.Huang S.W.Pan C.L.Tan q.Liu College of Materials Science and Engineering Chongqing UniversityChongqing 400044China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

In the present study,the texture evolution and mechanical anisotropy in a typical Mg–Zn–Ca alloy through hot cross rolling(CR)and unidirectional rolling(UR)were systematically *** results show that the rolling path greatly affects the annealed *** UR develops a texture with basal poles mainly distributing along the transverse direction(Td).By contrast,an ellipse-like(0002)texture with basal pole inclining largely away from the normal direction(Nd)is developed after hot cross rolling and ***,the CR is an effective method to tailor the texture of the experimental ***,this ellipse-like texture could not reserve during the subsequent unidirectional hot rolling and *** UR and CR plates exhibit a strong planar mechanical anisotropy compared with the traditional unidirectional rolled plate.

关键词： Mg alloys Hot cross rolling Texture Mechanical anisotropy

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采用超导磁体的小型MRI

科技纵览 2024年第7期 13-14页

作者： Charles q.Choi 不详

磁共振成像(MRI)能提供无辐射、无创的3d医学图像,彻底改变了医疗行业。不过,大多数MRI扫描仪都和一个房间差不多大,而且设计很复杂,耗电量也很高,需要功率大于25千瓦的电源产生高达1.5特斯拉的磁场。因此,这种扫描仪通常仅限于医院的... 详细信息

磁共振成像(MRI)能提供无辐射、无创的3d医学图像,彻底改变了医疗行业。不过,大多数MRI扫描仪都和一个房间差不多大,而且设计很复杂,耗电量也很高,需要功率大于25千瓦的电源产生高达1.5特斯拉的磁场。因此,这种扫描仪通常仅限于医院的专业科室使用。

关键词：医学图像专业科室超导磁体特斯拉医疗行业扫描仪耗电量 MRI

Magnetization reversal of antiferromagnetically coupled perpendicular anisotropy films driven by current

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Journal of Materials Science & Technology 2018年第5期34卷 832-835页

作者： x.T.Zhao Y.q.Zhao W.Liu Z.M.dai T.T.Wang x.G.Zhao Z.d.Zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

By inserting an ultrathin Pt layer at Co/Ru interface,we established antiferromagnetic coupling with outof-plane magnetization in Co/Ru/Co film stacks fabricated by *** achieve configuration suitable for free layer,the magnetic properties of the stacks have been investigated by changing the thickness of Co,Ru and Pt layers using an orthogonal wedges *** is found that magnetic properties for upper Co layer thinner than 0.5 nm are sensitive to little change in Ru *** continuity of upper Co layer by slightly increasing the thickness can effectively increase the squareness of minor *** switching magnetization of synthetic antiferromagnetic（SAF） structure is achieved by dC current under an in-plane static magnetic field of ± 500 *** structure is very promising for free layer in spintronic application.

关键词： Magnetic materials Multilayer structure Wedge Exchange coupling Antiferromagnetic

Experimental and numerical study of the effect of pulsatile flow on wall displacement oscillation in a flexible lateral aneurysm model

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Acta Mechanica Sinica 2019年第5期35卷 1120-1129页

作者： L.Z.Mu x.Y.Li q.Z.Chi S.q.Yang P.d.Zhang C.J.Ji Y.He G.Gao School of Energy and Power Engineering Dalian University of TechnologyDalian 116024China School of Biomedical Engineering Capital Medical UniversityBeijing 100069China The First Affiliated Hospital of University of Science and Technology of China Hefei 230036China

This study experimentally and numerically investigated the effect of pulsatile flow of different frequencies and outflow resistance on wall deformation in a lateral aneurysm.A method for constructing a flexible aneurysm model was developed,and a self-designed piston pump was used to provide the pulsatile flow conditions.A fluid-structure interaction simulation was applied for comparison with and analysis of experimental *** maximum wall displacement oscillation increased as the pulsation frequency and outflow resistance increased,especially at the aneurysm *** is an obvious circular motion of the vortex center accompanying the periodic inflow fluctuation,and the pressure at the aneurysm dome at peak flow increased as the pulsatile flow frequency and terminal flow resistance *** results could explain why abnormal blood flow with high frequency and high outflow resistance is one of the risk factors for aneurysm rupture.

关键词： Lateral aneurysm In vitro experiment Pulsatile flow Wall displacement oscillation Fluid-structure interaction simulation