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The preferential growth and related textural evolution during static recrystallization in a cold-rolled Mg-Zn-Gd alloy

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Journal of Magnesium and Alloys 2021年第3期9卷 818-828页

作者： L.Y.Zhao h.yan R.S.Chen En-hou han The Group of Magnesium Alloys and Their Applications Institute of Metal ResearchChinese Academy of Sciences62 Wencui RoadShenyang 110016China School of Materials Science and Engineering University of Science and Technology of China72 Wenhua RoadShenyang 110016China

The grain growth process plays an important role in the texture formation in magnesium *** microstructural and micro-textural evolution of a cold-rolled Mg-Zn-Gd alloy during annealing at 350℃for 60-190 min were tracked by quasi-in-situ electron backscatter diffraction *** results show that grain growth takes place gradually with the annealing time ***,the TD-split texture maintains the texture type but alters in three aspects-the increased tilting angle,the decreased pole intensity and the widened distribution of high-intensity *** with their c-axis tilting 45-70°from normal direction show preferential growth which is closely associated with the texture *** original grain size advantage is one of the important factors leading to the growth advantage,some grain boundaries,such as 50-60°[1^(-)21^(-)0],50-60°[2750],60-70°[1^(-)21^(-)0](18b),and 70-80°[1^(-)01^(-)0](10)are also considered to be related to this preferential growth.

关键词： Grain growth Preferential growth Texture Static recrystallization Magnesium alloys

Orientations of nuclei during static recrystallization in a cold-rolled Mg-Zn-Gd alloy

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Journal of Materials Science & Technology 2021年第1期60卷 162-167页

The static recrystallization process of a cold-rolled Mg-Zn-Gd alloy was tracked by a quasi-in-situ electron backscatter diffraction method to investigate the orientations of *** results show that orientation distribution of nuclei is associated with nucleation *** continuous static recrystallization nuclei display similar orientations to the parent grains with TD ***,discontinuous static recrystallization nuclei formed within the parent grains(TD-45~0 orientation) show random orientations and a variety of misorientation angles but preferred axes or .Interestingly,a special oriented nucleation is *** static recrystallization nuclei originated from boundaries of the parent grain(TD-70° orientation) show concentrated TD orientations in another side due to the preferred misorientation relationship 70°(∑18 b).It is speculated that these two special misorientation relationships are related to the dislocation type.

关键词： Mg alloys Orientation Nucleation Quasi-in-situ EBSD Static recrystallization

An efficient approach for solving mixed-integer programming problems under the monotonic condition

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Journal of Control and Decision 2016年第1期3卷 44-67页

作者： Mikhail A.Bragin Peter B.Luh Joseph h.yan Gary A.Stern Department of Electrical and Computer Engineering University of ConnecticutStorrsCTUSA Southern California Edison RosemeadCAUSA

Many important integer and mixed-integer programming problems are difficult to solve.A representative example is unit commitment with combined cycle units and transmission capacity *** transitions within combined cycle units are difficult to follow,and system-wide coupling transmission capacity constraints are difficult to *** example is the quadratic assignment *** presence of cross-products in the objective function leads to *** this study,building upon the novel integration of surrogate Lagrangian relaxation and branch-and-cut,such problems will be solved by relaxing selected coupling *** of the relaxed problem will be assumed and exploited and nonlinear terms will be dynamically *** linearity of the resulting problem will be exploited using *** achieve fast convergence,guidelines for selecting stepsizing parameters will be *** method opens up directions for solving nonlinear mixed-integer problems,and numerical results indicate that the new method is efficient.

关键词： integer monotonic programming mixed-integer monotonic programming branch-and-cut surrogate Lagrangian relaxation

Brain mechanisms of mental processing:from evoked and spontaneous brain activities to enactive brain activity

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Psychoradiology 2023年第1期3卷 66-72页

作者： Chi Zhang Yifeng Wang Xiujuan Jing Jin h.yan Institute of Brain and Psychological Sciences Sichuan Normal UniversityChengdu 610066China Tianfu College of Southwestern University of Finance and Economics Chengdu 610052China Sports Psychology Department China Institute of Sport ScienceBeijing 100061China

Within the context of the computer metaphor,evoked brain activity acts as a primary carrier for the brain mechanisms of mental ***,many studies have found that evoked brain activity is not the major part of brain ***,spontaneous brain activity exhibits greater intensity and coevolves with evoked brain activity through continuous *** and evoked brain activities are similar but not *** are not separate parts,but always dynamically interact with each ***,the enactive cognition theory further states that the brain is characterized by unified and active patterns of *** brain adjusts its activity pattern by minimizing the error between expectation and stimulation,adapting to the ever-changing ***,the dynamic regulation of brain activity in response to task situations is the core brain mechanism of mental *** the evoked brain activity and spontaneous brain activity,the enactive brain activity provides a novel framework to completely describe brain activities during mental *** is necessary for upcoming researchers to introduce innovative indicators and paradigms for investigating enactive brain activity during mental processing.

关键词： brain mechanism evoked brain activity spontaneous brain activity enactive brain activity mental processing

Effect of pre-deformation on microstructure and mechanical properties of WE43 magnesium alloy II: Aging at 250 and 300℃

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Journal of Magnesium and Alloys 2020年第1期8卷 103-110页

作者： Y.h.Kang Z.h.huang S.C.Wang h.yan R.S.Chen J.C.huang Guangdong-hong Kong Joint Research and Development Center on Advanced Manufacturing Technology for Light Alloys Guangdong Institute of Materials and ProcessingGuangzhou 510650China Institute of Metal Research Chinese Academy of Sciences Shenyang 110016China hong Kong Institute for Advanced Study Department of Materials Science and EngineeringCity University of Hong KongHong KongChina

In this work,the microstructural evolution and mechanical properties of a pre-deformed WE43 magnesium alloy when aged at 250 and 300℃ were further *** is found that the abundant deformation twins introduced by pre-deformation were maintained within the alloy during the aging *** particles formed at the twin boundaries and coarsened with aging time,especially at 300℃.When peak-aged at 250℃,the fine metastable β'''and β' precipitates formed in the un-deformed alloy have been transformed into relatively large β1 and β precipitates by the *** peak-aged at 300℃,the pre-deformation obviously refined the β *** properties indicate that pre-deformation can increase the yield strength by 19MPa and 54MPa for the peak-aged alloy at 250℃ and 300℃,respectively,and will not obviously deteriorate the tensile elongations.

关键词： WE43 magnesium alloy Pre-deformation Aging Microstructure Mechanical properties

Microstructural evolution of Mg-7Al-2Sn Mg alloy during multi-directional impact forging

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Journal of Magnesium and Alloys 2015年第3期3卷 180-187页

作者： M.G.Jiang h.yan L.Gao R.S.Chen The Group of Magnesium Alloys and Their Applications Institute of Metal ResearchChinese Academy of Sciences62 Wencui RoadShenyang 110016China University of Chinese Academy of Sciences 19 Yuquan RoadBeijing 100049China General Motors China Science Lab 56 Jinwan RoadPudongShanghai 201206China

Multi-directional impact forging(MDIF)was applied to a Mg-7Al-2Sn(wt.%)Mg alloy to investigate its effect on the microstructural *** process exhibited high grain refinement *** MDIF 200 passes,the grain size drastically decreased to 20µm from the initial coarse grains of~500µm due to dynamic recrystallization(DRX).Meanwhile,original grain boundaries remained during MDIF and large numbers of fine sphericalβ-Mg_(17)Al_(12) particles dynamically precipitated along the original grain boundaries with high Al concentration,acting as effective pinning obstacles for the suppression of DRXed grain ***,micro-cracks nucleated during MDIF and propagated along the interface between the remained globular or cubic Al-Mn particles and Mg matrix.

关键词： Magnesium alloy Forging Grain refinement Dynamic precipitation

Quasi-in-situ observing the rare earth texture evolution in an extruded Mg-Zn-Gd alloy with bimodal microstructure

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Journal of Magnesium and Alloys 2021年第5期9卷 1818-1827页

作者： M.G.Jiang C.Xu h.yan T.Nakata Z.W.Chen C.S.Lao R.S.Chen S.Kamado E.h.han College of Mechatronics and Control Engineering Shenzhen University3688 Nanhai AveShenzhen 518060China The Group of Magnesium Alloys and Their Applications Institute of Metal ResearchChinese Academy of Sciences62 Wencui RoadShenyang 110016China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Department of Mechanical Engineering Nagaoka University of TechnologyNagaoka 940-2188Japan

The static recrystallization and associated texture evolution were investigated in an extruded Mg-Zn-Gd alloy with bimodal microstructure based on a quasi-in-situ electron back-scatter diffraction(EBSD)*** typical rare earth(RE)texture formed during annealing,evolving from the bimodal microstructure with[1010]basal fiber texture that consisted of fine recrystallized(RXed)grains and coarse unrecrystallized(un RXed)grains elongated along the extrusion *** both RXed and un RXed regions,the RXed nucleation produced randomized orientations without preferred selection and the RXed grains with RE texture orientation had more intensive growth ability than those with basal fiber orientation,thereby leading to the preferred selection of RE texture orientation during grain *** relationships between stored strain energy,solute drag,grain growth and texture evolution are discussed in *** study provided direct evidence of the RE texture evolution in an extruded Mg-RE alloy,which assists in understanding the formation mechanisms for RE texture during extrusion and better developing wrought Mg alloys with improved formability.

关键词： Magnesium alloy Rare earth texture Extrusion Annealing Recrystallization

A Frequency Determination Method for Digitized NMR Signals

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Communications in Computational Physics 2014年第5期15卷 1343-1351页

作者： h.yan K.Li R.Khatiwada E.Smith W.M.Snow C.B.Fu P.-h.Chu h.Gao W.Zheng Indiana University BloomingtonIndiana 47408USA Center for Exploration of Energy and Matter Indiana UniversityBloomingtonIN 47408USA Department of Physics Shanghai Jiaotong UniversityShanghai200240China Triangle Universities Nuclear Laboratory and Department of Physics Duke UniversityDurhamNorth Carolina 27708USA.

We present a high precision frequency determination method for digitized NMR FID *** method employs high precision numerical integration rather than simple summation as in many other *** no independent knowledge of the other parameters of a NMR FID signal(phaseφ,amplitude A,and transverse relaxation time T_(2))this method can determine the signal frequency f_(0)with a precision of 1/(8π^(2)f_(0)^(2)T_(2)^(2))if the observation time T≫T_(2).The method is especially convenient when the detailed shape of the observed FT NMR spectrum is not well *** T2 is+∞and the signal becomes pure sinusoidal,the precision of the method is 3/(2π^(2)f_(0)^(2)T_(2))which is one order more precise than the±1 count error induced precision of a typical frequency *** of this method shows that the integration reduces the noise by bandwidth narrowing as in a lock-in amplifier,and no extra signal filters are *** a pure sinusoidal signal we find from numerical simulations that the noise-induced error in this method reaches the Cramer-Rao Lower Band(CRLB)on frequency *** the damped sinusoidal case of most interest,the noise-induced error is found to be within a factor of 2 of CRLB when the measurement time T is 2 or 3 times larger than *** discuss possible improvements for the precision of this method.

关键词： NMR FID numerical integration frequency determination noise reduction

Sn Oxide States of SnOx Films Induced by Vacuum Annealing

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电子显微学报 1997年第4期 87-88页

作者： h.yan\ G.h.Chen\ G.Y.Cao * (Department of Applied Physics, Beijing Polytechnic University, Beijing 100022) ( *State Key Lab. of MRD, Dalian Institute of Chemical Physics, Dalian 116023)

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关键词： SnO_x Films States Induced Annealing