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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

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

MICROSTRUCTURE AND MEChANICAL PROPERTIES OF Mg-Li ALLOy WITh Ca ADDITION

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Acta Metallurgica Sinica(English Letters) 2006年第5期19卷 355-361页

作者： h.B. Li G. C. yao Z.Q. Guo y.h. Liu h.J. yu h.B. Ji School of Materials ＆ Metallurgy Northeastern University Shenyang 110004 China

Mg-9wt%Li-2wt%Zn alloy was prepared and studied in this article. The addition of Ca to the alloy from 0.1wt% to 1wt% can refine the α-Mg and the best effect of refinement occurs when Ca content is 0.4wt%-0.5wt%. The billets can be rolled to thin sheets at room temperature, from which it is obvious that the addition of Ca improves alloys ormalin. while it decreases with the excess addition of Ca. The results also show that the ultimate tensile strength （UTS） and yield strength （yS） of the alloy with lwt% Ca may rise by 28% and 25%, respectively, however, the elongation decreases. It is clarified that the adsorption of proper Ca on the grain boundaries refines α-Mg and improves the tensile properties, but the presence of excess Ca and stable Ca2Mg6Zn3phase worsens the elongation.

关键词： calcium Mg-Li-Zn alloy cold rolling microstructure tensile property

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

Decorating crystalline yFe_(2-x)Al_(x) on the Mg_(60)La_(10)Ni_(20)Cu_(10) amorphous alloy as “hydrogen pump” to realize fast de/hydrogenation

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Journal of Materials Science & Technology 2024年第6期173卷 72-79页

作者： L.J.huang h.Wang L.Z.Ouyang M.Zhu h.J.Lin School of Materials Science and Engineering Key Laboratory of Advanced Energy Storage Materials of Guangdong ProvinceSouth China University of TechnologyGuangzhou 510641China Institute of Advanced Wear&Corrosion Resistance and Functional Materials Jinan UniversityGuangzhou 510632China

Mg-based amorphous alloys are one of the potential hydrogen storage materials but suffer from sluggish dehydrogenation/hydrogenation(de/hydrogenation)*** this work,as a new strategy,a hydrogen pump is built on the surface of amorphous alloys to solve this *** milling crystalline yFe_(2-x)Al_(x) hydrogen storage alloy with Mg_(60)La_(10)Ni_(20)Cu_(10) amorphous alloy,fine crystalline particles were seeded on amorphous alloy powder to form a“strawberry”*** to the TEM observation,a metallurgical bonding boundary formed between the Mg-based amorphous matrix and the y-Fe-Al crystalline *** microstructure and de/hydrogenation kinetics investigation,the“hydrogen pump”effect of the seeded crystalline alloy was confirmed,which makes it much easier for the hydrogen to dissociate on and diffuse through the surface of the Mg-based amorphous *** such effect,the h absorption rate of Mg_(60)La_(10)Ni_(20)Cu_(10) amorphous alloy became almost eight times faster and it absorbs ~2.8 wt.% in 1 h at 130℃ under 4.5 MPa-h_(2).Further,fast hydrogenation can even achieve at 70℃ and the low-temperature dehydrogenation kinetics of the amorphous hydride can be also greatly *** present work proves that surface modification is of great importance for obtaining Mg-based amorphous alloy with ideal hydrogen storage performance.

关键词： hydrogen storage Mg-based amorphous alloy hydrogen pump Composite structure

全球变暖背景下青藏高原北缘气候干湿变化模式的转型与机制——古气候视角

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中国科学：地球科学 2024年第6期54卷 1960-1979页

作者：李育张占森周雪如高铭君段俊杰薛雅欣尚好刘世瑜兰州大学西部环境教育部重点实验室兰州大学资源环境学院兰州730000

青藏高原北缘是季风西风协同影响的敏感区.夏季,水汽输送可以到达青海湖和祁连山东段;冬季,气候主要受控于西风.本文从古气候视角,对比了该区域中全新世暖期、中世纪暖期、现代暖期和未来百年暖期的干湿变化,发现中全新世暖期主要受轨... 详细信息

青藏高原北缘是季风西风协同影响的敏感区.夏季,水汽输送可以到达青海湖和祁连山东段;冬季,气候主要受控于西风.本文从古气候视角,对比了该区域中全新世暖期、中世纪暖期、现代暖期和未来百年暖期的干湿变化,发现中全新世暖期主要受轨道控制的东亚夏季风影响,区域整体表现出温暖湿润的气候特征;中世纪暖期主要受控于太阳辐射,存在暖干的现象;现代暖期和未来百年暖期主要由温室气体增加导致的温度升高控制,气候干旱化趋势显著.青藏高原北缘现代暖期和未来百年暖期的干湿格局与中世纪暖期类似,而持续升温会导致西风带扩张,气候逐渐湿润,未来干湿变化将与中全新世暖期更加相似.

关键词：青藏高原北缘干湿变化暖期相似驱动机制未来评估

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二叶主动脉瓣伴动脉夹层破裂1例

法医学杂志 2024年第1期40卷 77-79页

作者：徐碧宇吴晨阳姬艳琦李莹莹宋旭东华北理工大学附属医院病理科河北唐山063000

1案例1.1简要案情及病史摘要某男,35岁,因“持续性胸闷18 h”入院。入院后1 h行急性冠状动脉造影检查示:左冠状动脉开口及起源正常,左主干、前降支及回旋支正常,可见前降支至右冠状动脉侧支形成,血流分级(thrombolysis in myocardial in... 详细信息

1案例1.1简要案情及病史摘要某男,35岁,因“持续性胸闷18 h”入院。入院后1 h行急性冠状动脉造影检查示:左冠状动脉开口及起源正常,左主干、前降支及回旋支正常,可见前降支至右冠状动脉侧支形成,血流分级(thrombolysis in myocardial infarction,TIMI)1级;右冠状动脉开口朝上变异,近段次全闭塞,前向血流TIMI1级;结论为右冠状动脉单支病变,右冠状动脉开口朝上变异,冠状动脉分布呈右优势型。遂于右冠状动脉近段植入hELICOS(4.0 mm×22.0 mm)支架1枚。

关键词：法医病理学二叶主动脉瓣主动脉夹层动脉夹层破裂

基于MRI的自动化多任务深度学习系统评估冈上肌腱损伤

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国际医学放射学杂志 2024年第4期 499-500页

作者： M.Ni y.Q.Zhao L.h.Zhang W.Chen Q.Z.Wang C.y.Tian 常雪

摘要目的建立一个自动化、多任务、基于MRI的深度学习系统，用于精细评估冈上肌腱（SST）损伤。方法根据关节镜检查结果，将3 087例病人分为SST正常组、退变组和

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In vitro Study on Biodegradable AZ31 Magnesium Alloy Fibers Reinforced PLGA Composite

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Journal of Materials Science & Technology 2013年第6期29卷 545-550页

作者： y.h.Wu N.Li y.Cheng y.F.Zheng y.h.n Center for Biomedical Materials and Tissue Engineering Academy for Advanced Interdisciplinary StudiesPeking University Department of Materials Science and Engineering College of EngineeringPeking University State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University

AZ31 magnesium alloy fibers reinforced poly（lactic-co-glycolic acid）（PLGA） composites were prepared and their mechanical property, immersion corrosion behavior and biocompatibility were studied. The tensile test showed that with the addition of AZ31 fibers, the composites had a significant increment in tensile strength and elongation. For the direct cell attachment test, all the cells showed a healthy morphology and spread well on the experimental sample surfaces. The immersion results indicated that ph values of the immersion medium increased with increasing AZ31 fiber contents. All the in vitro experimental results indicated that this new kind of magnesium alloy fibers reinforced PLGA composites show a potential for future biomedical applications.

关键词： Biomaterials Corrosion Polymeric composites AZ31 magnesium fiber