检索结果-南通市图书馆

Average Estimation of Semiparametric Models for High-Dimensional Longitudinal Data

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2020年第6期33卷 2013-2047页

作者： zhao zhihao ZOU Guohua School of Mathematicnl Sciences Capital Normal UniversityBeijing 100048China

Model average receives much attention in recent *** paper considers the semiparametric model averaging for high-dimensional longitudinal *** minimize the prediction error,the authors estimate the model weights using a leave-subject-out cross-validation *** optimality of the proposed method is proved in the sense that leave-subject-out cross-validation achieves the lowest possible prediction loss *** studies show that the performance of the proposed model average method is much better than that of some commonly used model selection and averaging methods.

关键词： Asymptotic optimality high-dimensional longitudinal data leave-subject-out cross-validation model averaging semiparametric models

Optogenetic activation of intracellular signaling based on light-inducible protein-protein homo-interactions

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2022年第1期17卷 25-30页

作者： Peiyuan Huang zhihao zhao Liting Duan Department of Biomedical Engineering The Chinese University of Hong KongSha TinHong Kong Special Administrative RegionChina Shun Hing Institute of Advanced Engineering(SHIAE) The Chinese University of Hong KongSha TinHong Kong Special Administrative RegionChina

Dynamic protein-protein interactions are essential for proper cell *** events—physical interactions between the same type of proteins—represent a pivotal subset of protein-protein interactions that are widely exploited in activating intracellular signaling *** of modulating protein-protein interactions with spatial and temporal resolution are greatly desired to decipher the dynamic nature of signal transduction *** emerging optogenetic technology,based on genetically encoded light-sensitive proteins,provides promising opportunities to dissect the highly complex signaling networks with unmatched specificity and spatiotemporal *** we review recent achievements in the development of optogenetic tools enabling light-inducible protein-protein homo-interactions and their applications in optical activation of signaling pathways.

关键词： cryptochrome 2 homo-interaction intracellular signaling light light-induced protein-protein interaction light-oxygen-voltage-sensing domain light-sensitive proteins optogenetics phytochrome signal transduction

Microstructure and mechanical properties of low frequency electromagnetic casting 7075 aluminum alloy

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2012年第2期25卷 160-168页

作者： Gaosong WANG zhihao zhao Jianzhong CUI Qiang GUO Key Laboratory of Electromagnetic Processing of Materials Ministry of EdudationNortheastern UniversityShenyang 110819China

This work explores the microstructure of low frequency electromagnetic casting （LFEC） 7075 aluminum alloys and investigates the effect of heat treatment process on its mechanical properties via the mechanical properties test, X-ray diffraction and transmission electron microscopy. It was found that the grains of LFEC ingot were finer and more evenly distributed than that of the conventional direct chill cast （DC） ingots. The microstructure of LFEC ingot extruded kept their original as-cast struc- ture with small and fine grains. With the same extrusion ratio, the average grain diameters of LFEC and conventional DC extruded were about 10 and 20 #m, re- spectively. LFEC extruded also had a better aging property, since the regime of T6 treatment peak value aging was at 120 ~C for 24 h, the tensile strength and hardness （HV） of the LFEC extruded were 673.50 MPa and 194.62, respectively, which were all higher than those of the conventional DC extruded, indicating that the process regime can be applied in the industrial production.

关键词： LFEC Aging 7075 aluminum alloy Microstructure Property

On the low cycle fatigue behaviour of an Al-Zn-Mg-Cu alloy processed via non-isothermal ageing

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2024年第1期168卷 227-238页

作者： Guangyi Guo Guofu Xu Yuan Tang zhihao zhao zhihao Yi Haoran Li Ruohan Wang Xiaoyan Peng School of Materials Science and Engineering Central South UniversityChangsha 410083China Key Laboratory of Nonferrous Materials Science and Engineering of Ministry of Education Changsha 410083China

The low cycle fatigue behaviour of an Al-Zn-Mg-Cu alloy processed via non-isothermal ageing(NIA)was examined at different strain *** showed that NIA improved the low cycle fatigue life(more than 7000 cycles)by optimising the precipitate configuration within 5.5 h while maintaining comparable mechanical properties(570 MPa for tensile strength)and conductivity(nearly 39%IACS)to conventional isothermal ageing,*** observation combined with molecular dynamic simula-tion revealed that precipitation configuration manipulated by NIA had a crucial effect on fatigue resis-tance.A great number of repeatedly sheared and locally destructed GP zones enhanced co-planar slip and slip localisation in the under-aged alloy during the early stage of NIA,responsible for the dramatic displacement steps on the surface and resultant poor fatigue *** the NIA further proceeded,moderately coarsened precipitates with an average dimension of 6.0 nm and elevated number density ef-fectively impeded the dislocation movement and weaken the slip localisation to a great extent,improving the fatigue performance within a few hours.

关键词： Non-isothermal ageing Fatigue Al-Zn-Mg-Cu alloy Precipitate manipulation Slip localization

Effect of Mn on microstructures and mechanical properties of Al-Mg-SiCu-Cr-V alloy

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Foundry 2012年第4期9卷 349-355页

作者： zhao zhihao Meng Yi Cui Jianzhong Key Laboratory of Electromagnetic Processing of Materials Ministry of EducationNortheastern UniversityShenyang 110819China

In order to improve the performances of the Al-Mg-Si-Cu-Cr-V alloy,various amounts of Mn(0-0.9wt.%) were *** effect of this Mn on the microstructures and mechanical properties of Al-Mg-Si-Cu-Cr-V alloys in different states,especially after hot extrution and solid solution treatment,was systematically studied using scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),and mechanical tests at room *** results show that 0.2wt.% Mn can both refine the as-cast microstructure of the alloy and strengthen the extrusion+T6 state alloy without damaging the plasticity badly due to the formation of Al 15(FeMn) 3 Si 2 and Al 15 Mn 3 Si 2 *** with the extrusion+T6 state alloy without Mn addition,the ultimate tensile strength and yield strength of the alloy with 0.2wt.% Mn addition are increased from 416.9 MPa to 431.4 MPa,360.8 MPa to 372 MPa,*** elongation of the extrusion+T6 state alloy does not show obvious change when the Mn addition is less than 0.5wt.%,and for the alloy with 0.2wt.% Mn addition its elongation is still as high as 15.6%.However,when over 0.7wt.% Mn is added to the alloy,some coarse,stable and refractory AlVMn and Al(VMn)Si phases *** coarse phases can reduce the effect of Mn on the inhibition of re-crystallization;and they retain the angular morphology permanently after the subsequent deformation process and heat *** damages the mechanical properties of the alloy.

关键词： Al-Mg-Si-Cu-Cr-V alloy Mn content microstructure mechanical properties

Effect of casting speed on surface quality of horizontal direct chill casting 7075 aluminum alloy ingot

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2011年第5期24卷 399-404页

作者： Qingfeng ZHU zhihao zhao Jianzhong CUI Xiangjie WANG Ke QIN Key Laboratory of Electromagnetic Processing of Materials Ministry of Education Northeastern University Shenyang 110819 China

7075 aluminum alloy ingot with the diameter izontal direct chill casting in different casting of 100 mm has been produced by horspeed. The effect of the casting speed on the ingot surface and subsurface layer was studied by surface observation and subsurface structure analysis. It was found that increasing the casting speed results in the adding of segregation knots in the ingot surface. The thickness of the dendrite microstrueture layer in the subsurface reduces with increasing the casting speed. And the elements of Zn, Cu and Mg enrich in the coarse dendrite microstructure layer of the ingot.

关键词： Horizontal direct chill casting Casting speed 7075 aluminumalloy Surface quality

Effect of combined electromagnetic fields on surface quality and structure of a HDC casting 5182 Al alloy ingot

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2012年第6期25卷 453-460页

作者： Qingfeng ZHU zhihao zhao Yubo ZUO Xiangjie WANG Jianzhong CUI Key Laboratory of Electromagnetic Processing of Materials Ministry of Education Northeastern University Shenyang 110819 China

5182 Al alloy ingots with the diameters of 100 mm are produced by conventional and combined electromagnetic fields （CEMF） horizontal direction chill （HDC） cast- ing process. The effect of CEMF on the ingot surface quality and floating grains is investigated. The results show that the CEMF is effective in reducing the segregation layer in both top and bottom sub-surfaces. Big floating grains with coarse dendrite arms mainly distribute in the crescent-shaped area near the bottom in the conven- tional HDC casting ingot. With the application of the CEMF, they disappear in the whole cross section of the HDC casting ingot and the equiaxed grains are significantly refined.

关键词： Aluminum alloy Combined electromagnetic field Horizontaldirect chill casting Structure Surface quality

Investigation of Out-Phase Electromagnetic Casting of Aluminum Alloy

在线全文

学校读者我要写书评

暂无评论

稀有金属材料与工程 2009年第A03期38卷 73-77页

作者： zhao zhihao Zhu Qingfeng Wang Xiangjie Cui Jianzhong Key Laboratory of Electromagnetic Processing of Materials Ministry of Education Northeastern University Shenyang 110004 China

The influences of out-phase electromagnetic field on the as-cast structure of horizontal direct chill casting aluminum alloy ingot were experimental by and numerical by studied. The results of numerical analysis show that the interaction of the out-phase electromagnetic field and the melt can generate an electromagnetically induced forced flow in the melt, which, in turn, changes flow pattern and temperature field in the mold. The as-cast structure of the ingot can be greatly improved by the changes of flow pattern and temperature field. The results of experimental analysis show that with application of out-phase electromagnetic field, temperature distribution in the melt is more uniform, grain morphology changes from columnar grains to equiaxed grains and grain size decreases.

关键词：铝合金异相电磁场电磁感应温度

Microstructure and RRA Treatment of LFEC 7075 Aluminum Alloy Extruded Bars

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2013年第1期28卷 184-191页

作者：王高松 zhao zhihao CUI Jianzhong GUO Qiang Key Laboratory of Electromagnetic Processing of Materials Ministry of Education Northeastern University

The microstructures after casting and extruding, the mechanical properties and electrical conductivity after RRA treatment of conventional DC casting and low frequency electromagnetic casting （LFEC） 7075 aluminum alloy were investigated. The results showed that finer grains which distributed more homogeneously was obtained in LFEC ingots compared with those conventional DC ingots. The extruded bars of LFEC alloy kept its fine grain features of original as-cast structure. In the RRA treatment, with the extension of second aging time, the tensile strength and hardness of alloy decreased, but the electrical conductivity increased. Meanwhile, as the second aging temperature raised, the phase change rate in precipitation also increased. Under the same conditions, extruded bars of LFEC alloy had better performance than that of conventional DC cast alloy. The optimum RRA heat treatment process was 120 ℃/24 h＋180 ℃/30 min＋120 ℃/24 h. The LFEC extruded bars acquired tensile strength 676.64 MPa, hardness 198.18, and electrical conductivity 35.7% IACS respectively, which were higher than that in the T6 temper, indicating that a notable RRA response takes place in LFEC extruded bars, whose second-step retrogression time was 30 min, and it was suitable for mass production.

关键词： RRA LFEC 7075 aluminum alloy microstructure property