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Microstructure and mechanical properties of TiAl/TiAl joints brazed with a newly developed Ti–Ni–Nb–Zr quaternary filler alloy

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Progress in Natural Science:Materials International 2022年第6期32卷 758-768页

作者： h.S.Ren y.L.Shang X.y.Ren y.J.Jing h.P.Xiong y.y.Cheng Welding and Plastic Forming Division Beijing Institute of Aeronautical Materials

A novel Ti-Ni-Nb-Zr quaternary filler alloy with the composition of Ti-(19～25)Ni-(15～25)(Nb+Zr)(wt.%) was *** filler alloy was composed of(Ti,Nb)ss,(Ti,Zr,Nb)ss+(Ti,Zr)2Ni,α-Ti and Ti2Ni *** was fabricated into filler foil with a thickness of about 45 μm by a rapid solidification *** results indicate that the liquidus temperature of the Ti-Ni-Nb-Zr brazing alloy was about 978℃,and the brazing alloy presented excellent wettability on TiAl *** TiAl joint mainly consisted of β/B2 phase,Ti2Al,Ti2AlNi and α2-Ti3Al *** diffusion of Al atom from base metal to brazed seam led to the formation of Ti2Al and *** that no previously references on XRD pattern of Ti2AlNi compound can be found,Ti2AlNi cast alloy specimen was specially prepared and XRD peaks were specially *** micro-hardness and bending strength tests of the Ti2AlNi phase were carried out,and the results were 761 hV and 192 MPa,*** brazing parameters of 1010 ℃/10 min offered the joint shear strength of 280 MPa at room temperature,and the joints exhibited tensile strength of 372 MPa at room temperature and 340 MPa at 750 ℃,indicating that the newly developed filler alloy could offer a stable high-temperature strength.

关键词： TiAl Brazing Filler alloy Microstructure Mechanical properties

A hyperbolic Lindstedt-Poincare method for homoclinic motion of a kind of strongly nonlinear autonomous oscillators

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Acta Mechanica Sinica 2009年第5期25卷 721-729页

作者： y.y.Chen S.h.Chen K.y.Sze Department of Applied Mechanics and Engineering Sun yat-sen University Department of Mechanical Engineering The University of Hong Kong Department of Applied Mechanics and Engineering Sun Yat-sen University

A hyperbolic Lindstedt-Poincare method is presented to determine the homoclinic solutions of a kind of nonlinear oscillators, in which critical value of the homoclinic bifurcation parameter can be determined. The generalized Lienard oscillator is studied in detail, and the present method＇s predictions are compared with those of Runge-Kutta method to illustrate its accuracy.

关键词： Lindstedt-Poincare method hyperbolic function Nonlinear autonomous oscillator - homoclinic orbit

An Initial Analysis of a Strongly Lensed QSO Candidate Identified by LAMOST

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Research in Astronomy and Astrophysics 2023年第10期23卷 349-356页

作者： y.h.Chen M.y.Tang h.Shu h.Tu Institute of Astrophysics Chuxiong Normal UniversityChuxiong 675000China School of Physics and Electronical Science Chuxiong Normal UniversityChuxiong 675000China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650011China Department of Astronomy Yunnan Universityand Key Laboratory of Astroparticle Physics of Yunnan ProvinceKunming 650091China Physics Department&Shanghai Key Lab for Astrophysics Shanghai Normal UniversityShanghai 200234China

From 2011 to 2021,LAMOST has released a total of 76,167 quasar *** try to search for gravitationally lensed QSOs by limiting coordinate differences and redshift differences of these *** name,brightness,spectrum,photometry and other information of each QSO will be visually checked *** attention should be paid to check whether there are groups of galaxies,gravitationally lensed arcs,Einstein crosses,or Einstein rings near the *** careful selection,we select LAMOST J160603.01+290050.8(A)and LAMOST J160602.81+290048.7(B)as a candidate and perform an initial *** A and B are336 apart and they display blue during photometric *** redshift values of components A and B are0.2%different,their Gaia_g values are 1.3%different,and their ugriz values are 1.0%or less *** the spectra covering from 3690 to 9100?,the emission lines of C II,Mg,hγ,OⅢ,and hβare present for both components A and B and the ratio of flux(B)to flux(A)from LAMOST is basically a constant,around ***,no galaxies have been found between components A and *** et *** them as binary *** we accidentally find a galaxy group near components A and *** the center of dark matter in the galaxy group is at the center between components A and B,components A and B are probably gravitationally lensed *** estimate that the Einstein mass is 1.46×10^(11)M_⊙and the total mass of the lens is1.34×10^(13)M_⊙.The deflection angle is 197 at positions A and B and the velocity dispersion is 261 km s^(-1).Theoretically,this candidate could be a pair of fold images of a strong lensing system by a galaxy group,and we will investigate the possibility when the redshifts of nearby galaxies are available.

关键词： gravitational lensing:strong (galaxies:)quasars:individual(LAMOST J1606+2900) techniques:imaging spectroscopy

A hOMOTOPy METhOD OF SWITChING SOLUTION BRANChES AT ThE PITChFORK BIFURCATION POINT

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Journal of Computational Mathematics 2001年第3期19卷 299-308页

作者： Cong, y.-h. Zhu, Z.-y. College of Mathematical Sciences Shanghai Teachers University Shanghai 200234 China

Provides information on a study which proposed a continuation method for switching solution branches at a pitchfork point. Problem of the standard pitchfork; Information on the systems of equations; Numerical examples... 详细信息

关键词： homotopy method switching solution branches pitchfork point

The Log-Concavity of Kazhdan-Lusztig Polynomials of Uniform Matroids

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Journal of Systems Science & Complexity 2023年第1期36卷 117-128页

作者： XIE Matthew h y ZhANG Philip B College of Science Tianjin University of TechnologyTianjin 300384China College of Mathematical Science Tianjin Normal UniversityTianjin 300387China

Elias,et al.(2016)conjectured that the Kazhdan-Lusztig polynomial of any matroid is *** by a computer proof of Moll’s log-concavity conjecture given by Kauers and Paule,the authors use a computer algebra system to pr... 详细信息

关键词： holonomicFunctions Kazhdan-Lusztig polynomial log-concavity uniform matroid

Microstructural Dependence of Damping Behaviour of Eutectoid Zn-Al Based Alloy (ZA27)──Discussion of "Damping Behaviour and Mechanism of Graphite Particulate Reinforced Metal Matrix Composites

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Journal of Materials Science & Technology 1999年第2期15卷 178-180页

作者： Zhu, y.h. Institute de Investigaciones en Materiales UNAM Mexico D.F. 04510 Apart.P.70-360 Mexico Dept. of Manufacturing Engineering Hong Kong Polytechnic University Hong Kong

Friction stir spot welding of SPCC low carbon steel plates at extremely low welding temperature

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Journal of Materials Science & Technology 2019年第5期35卷 733-741页

作者： y.F.Sun h.Fujii y.Sato y.Morisada Joining and Welding Research Institute Osaka University 11-1 Mihogaoka Ibaraki 567-004Japan School of Materials Science and Engineering Zhengzhou University Zhengzhou 450001 China

Friction stir spot welding (FSSW) was applied to 2.0 mm thick steel plate cold-rolled commercial (SPCC) low carbon steel plates at a very low rotation speed that ranged from 5 to 50rpm, which was much lower than that generally used for the conventional FSSW technique. Due to the very low heat input, the welding processes could therefore be completed at a peak welding temperature below 160℃. As a result, a significantly refined microstructure with an average grain size of about 0.41μm was formed in the stir zone of the joints and the JI {0-11 } and J2{1-1O} shear textures were the dominant components, which are different from the D1{11-2} and D2{-1-12} shear textures formed in the conventional FSSW joints. In addition, no heat affected zone could be detected along the crosssectional plane of the joints. Although a few void-like non-bonded areas were still observed along the interface between the upper and lower steel plates, the shear tensile loads of the joints increased to about 10.0 kN when welded at a condition of 8t, 20rpm and 30 s, and the joints fractured through the plug failure mode.

关键词： Friction stir spot welding Dynamic recrystallization Microstructure Steel

MEShFREE METhOD BASED ON POINT COLLOCATION FOR METAL FORMING SIMULATION

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Acta Metallurgica Sinica(English Letters) 2006年第2期19卷 79-84页

作者： h.y. Wen X.h. Dong X.y. Ruan Department of Plasticity Forming Engineering Shanghai Jiaotong University Shanghai 200030 China

A meshfree method based on reproducing kernel approximation and point collocation is presented for analysis of metal ring compression. The point collocation method is a true meshfree method without the employment of a background mesh. It is shown that, in a point collocation approach, the remesh problem because of the mesh distortion in FEM （finite element method） and the low efficiency in Galerkin-based meshfree method are avoided. The corrected kernel functions are introduced to the stabilization of free-surface boundary conditions. The solution of symmetric ring compression problem is compared with a conventional finite element solution, and reasonable results have been obtained.

关键词： meshfree method RKPM (reproducing kernel particle method) point collocation metal forming frictional contact

Comparative Gene Expression Analysis of Mouse and human Cardiac Maturation

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Genomics, Proteomics & Bioinformatics 2016年第4期14卷 207-215页

作者： hideki Uosaki y-h Taguchi Division of Cardiology The Johns Hopkins University School of Medicine Department of Physics Chuo University

Understanding how human cardiomyocytes mature is crucial to realizing stem cell-based heart regeneration, modeling adult heart diseases, and facilitating drug discovery. however, it is not feasible to analyze human samples for maturation due to inaccessibility to samples while cardiomyocytes mature during fetal development and childhood, as well as difficulty in avoiding variations among individuals. Using model animals such as mice can be a useful strategy; nonetheless, it is not well-understood whether and to what degree gene expression profiles during maturation are shared between humans and mice. Therefore, we performed a comparative gene expression analysis of mice and human samples. First, we examined two distinct mice microarray platforms for shared gene expression profiles, aiming to increase reliability of the analysis. We identified a set of genes displaying progressive changes during maturation based on principal component analysis. Second, we demonstrated that the genes identified had a differential expression pattern between adult and earlier stages （e.g., fetus） common in mice and humans. Our findings provide a foundation for further genetic studies of cardiomyocyte maturation.

关键词： Cardiac maturation Comparative gene expressionanalysis Microarray meta analysis Principal component analysis Feature selection