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Nanoindentation of soft solids by a fla punch

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Acta Mechanica Sinica 2015年第4期31卷 531-535页

作者： G.F.Wang x.r.Niu Department of Engineering Mechanics SVL Xi’an Jiaotong University Department of Mechanical and Biomedical Engineering City University of Hong Kong

Measuring the surface tension and elastic mod- ulus of soft materials and biological tissues under different physiological and pathological conditions is of significance for understanding various phenomena associated with defor- mation. In this paper, the nanoindentation of a circular fiat punch on a soft solid is analyzed with the influence of surface tension. By solving the corresponding singular integral equa- tion, the relation between load and indent depth is obtained. When the radius of the flat punch shrinks to the same order as the ratio of surface tension to elastic modulus, surface ten- sion significantly affects the indentation load-depth relation, which provides a facile method to measure surface tension in soft solids and biological tissues.

关键词： Nanoindentation Surface tension Soft solid Biological tissue

Characterization of bright betatron radiation generated by direct laser acceleration of electrons in plasma of near critical density

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Matter and radiation at Extremes 2024年第2期9卷 26-35页

作者： J.Cikhardt M.Gyrdymov S.Zähter P.Tavana M.M.Günther N.Bukharskii N.Borisenko J.Jacoby x.F.Shen A.Pukhov N.E.Andreev O.N.rosmej Faculty of Electrical Engineering Czech Technical University in Prague16627 Prague 6Czech Republic Goethe University FrankfurtMax-von-Laue-Straße 160438 Frankfurt am MainGermany GSI Helmholtzzentrum für Schwerionenforschung GmbH Planckstraße 164291 DarmstadtGermany Focused Energy GmbH Im Tiefen See 4564293 DarmstadtGermany National research Nuclear University MEPhI Kashirskoe shosse 31115409 MoscowRussian Federation Lebedev Physical Institute rAS Leninskiy Prospekt 53119991 MoscowRussian Federation Heinrich-Heine-University Düsseldorf Universitätsstrasse 1DüsseldorfGermany Joint Institute for High Temperatures RASIzhorskaya st.13Bldg.2125412 MoscowRussian Federation Moscow Institute of Physics and Technology Institutskiy Pereulok 9141700 DolgoprudnyRussia

Directed x-rays produced in the interaction of sub-picosecond laser pulses of moderate relativistic intensity with plasma of near-critical density are investigated. Synchrotron-like (betatron) radiation occurs in the process of direct laser acceleration (DLA) of electrons in a relativisticlaser channel when the electrons undergo transverse betatron oscillations in self-generated quasi-static electric and magnetic fields. In anexperiment at the PHELIx laser system, high-current directed beams of DLA electrons with a mean energy ten times higher than the ponderomotive potential and maximum energy up to 100 MeV were measured at 10^(19) W/cm^(2)laser intensity. The spectrum of directed x-raysin the range of 5–60 keV was evaluated using two sets of ross filters placed at 0°and 10°to the laser pulse propagation axis. The differential x-ray absorption method allowed for absolute measurements of the angular-dependent photon fluence. We report 10^(13) photons/sr withenergies >5 keV measured at 0°to the laser axis and a brilliance of 10^(21) photons s^(−1) mm^(−2) mrad−2(0.1%BW)−1. The angular distributionof the emission has an FWHM of 14°–16°. Thanks to the ultra-high photon fluence, point-like radiation source, and ultra-short emissiontime, DLA-based keV backlighters are promising for various applications in high-energy-density research with kilojoule petawatt-class laserfacilities.

关键词： laser acceleration critical

Nematic and smectic stripe phases and stripe-Sk x transformations

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Science China(Physics,Mechanics & Astronomy) 2022年第4期65卷 112-119页

作者： Hai-Tao Wu xu-Chong Hu x.r.Wang Department of Physics The Hong Kong University of Science and TechnologyHong Kong 999077China HKUST Shenzhen research Institute Shenzhen 518057China

Based on the findings of skyrmion nature of stripes and the metastability of a state of an arbitrary number of skyrmions,precisely controlled manipulation of stripes of skyrmion number 1 in pre-designed structures and mutual transformation between helical states and skyrmion crystals(Sk xs)are demonstrated in chiral magnetic *** a proof of the concept,we show how to use patterned magnetic fields and spin-transfer torques(STTs)to generate nematic and smectic stripe phases,as well as“UST”mosaic from three curved *** one stripe into many pieces and coalescing several skyrmions into one by various external fields are good ways to transform helical states and Sk xs from each other.

关键词： spintronic Landau-Lifshitz-Gilbert equation simulation stripe skyrmion skyrmion crystal nematic phase

考虑短路电流暂态分量的高压交流系统短路故障限流器参数设计

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高电压技术 2024年第8期50卷 3769-3782,I0034-I0036页

作者：刘嘉伟袁佳歆周航李旭哲莫作权武汉大学电气与自动化学院电网环境保护全国重点实验室武汉430072

在高压交流输电系统(HVAC)发生短路故障时,极大可能会产生含暂态分量(short circuit current transient component,SCTC)的短路故障电流;当SCTC含量很大时甚至会产生短路电流的零点漂移现象,会对故障限流器(fault current limiter,FCL)... 详细信息

在高压交流输电系统(HVAC)发生短路故障时,极大可能会产生含暂态分量(short circuit current transient component,SCTC)的短路故障电流;当SCTC含量很大时甚至会产生短路电流的零点漂移现象,会对故障限流器(fault current limiter,FCL)的限流工作和参数设计造成很大的影响。针对上述问题,提出了一种SCTC泄能型故障限流器(SCTC energy drain type fault current limiter,SEDFCL)及其参数设计方法,可以加快SCTC的衰减。首先,分析了SEDFCL与SCTC的相互影响和SEDFCL的电磁路工作机理,并研究了SEDFCL场路耦合特性,对电磁参数进行了设计;然后,通过有限元仿真搭建了220 kV SEDFCL模型,探究了SEDFCL结构的有效性、合理性、rC参数的调节作用,以及故障情况下SEDFCL功能的有效性;最后,搭建一台小容量样机,建立试验平台并进行样机试验,证实SEDFCL结构和功能的有效性。与传统五柱式限流器(five-column hybrid excitation type FCL,FHETFCL)相比,SEDFCL将时间常数显著降低117.66%,限流效果提高6.29%。

关键词：暂态分量故障限流器泄能场路耦合有限元分析

Wenchuan Post-earthquake reconstruction by Utilizing Composite Tubular Construction and FrP retrofitting Technology

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四川大学学报（工程科学版） 2009年第3期41卷 231-247页

作者： ZHAO x L AL-MAHAIDI r Dept. of Civil Eng. Monash Univ. Clayton VIC 3800 Australia

This paper presents two possible construction methods that could be adopted in the Wenchuan post-earthquake *** is the composite tubular construction and the other is FrP(Fibre reinforced Polymer) retrofitting *** background of these two methods,the existing research and relevance to Whenchuan post-earthquake reconstruction are described.

关键词：抗振结构建筑结构建筑物 FrP 地震重建

Hepatology|肠源性IL-33双重调控缺氧诱导因子1α信号促进三甲胺-N-氧化物生成并加重代谢相关脂肪性肝病进展

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临床肝胆病杂志 2024年第9期40卷 1766-1766页

作者：海素平华中科技大学同济医学院附属同济医院

代谢相关脂肪性肝病(MASLD)是一种以肝脂质异常沉积为特征,同时伴随心脏代谢危险因素的代谢性疾病,现已成为全世界最常见的慢性肝病。MASLD的发展与肠道稳态的失衡紧密相连,紊乱的肠道菌群及其代谢物通过受损的肠道屏障到达肝脏,引起肝... 详细信息

代谢相关脂肪性肝病(MASLD)是一种以肝脂质异常沉积为特征,同时伴随心脏代谢危险因素的代谢性疾病,现已成为全世界最常见的慢性肝病。MASLD的发展与肠道稳态的失衡紧密相连,紊乱的肠道菌群及其代谢物通过受损的肠道屏障到达肝脏,引起肝脏的代谢紊乱和炎症。

关键词：脂肪性肝病缺氧诱导因子1α 慢性肝病肠源性代谢性疾病肠道屏障三甲胺肠道稳态

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光谱参数在青藏高原东北缘尖扎盆地风成红黏土古气候记录中的应用

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中国科学：地球科学 2024年第6期54卷 1980-1995页

作者：符超峰田菊娥徐新文宋友桂左俊王凤陈琳李鹏飞强小科长安大学地球科学与资源学院西安710054 中国科学院地球与环境研究所黄土与第四纪地质国家重点实验室西安710061 西北大学城市与环境学院西安710069 中国科学院第四纪科学与全球变化卓越创新中心西安710061

反射光谱测量具有快速、廉价和无损的特点,可提供岩石和沉积物所含矿物的重要信息.通过测量青藏高原东北缘晚中新世红黏土沉积物的反射光谱,旨在寻找一种可以快速获取古气候变化信息的方法.利用尖扎盆地红黏土沉积物的可见光/近红外(VN... 详细信息

反射光谱测量具有快速、廉价和无损的特点,可提供岩石和沉积物所含矿物的重要信息.通过测量青藏高原东北缘晚中新世红黏土沉积物的反射光谱,旨在寻找一种可以快速获取古气候变化信息的方法.利用尖扎盆地红黏土沉积物的可见光/近红外(VNIr)和短波红外(SWIr)波段的光谱数据,分析了它们与传统古气候指标黏土矿物含量和环境磁学参数的关系.结果表明, VNIr参数D500、D900、r500和r900(其中D和r分别代表500nm和900nm附近吸收峰的深度和反射率)与磁化率、频率磁化率和深海氧同位素关系密切,且它们对温度较为敏感.VNIr参数的频谱分析结果表明,它们可以反映气候在轨道时间尺度上的变化. SWIr参数AS1400、D1400/D1900、D1900(其中AS代表1400nm附近吸收峰的不对称性)与伊利石和蒙脱石的相对含量有关,且它们对风化强度更敏感.尖扎盆地风成红黏土沉积物的光谱参数可以反映~8.5Ma青藏高原隆升引起的区域气候变化和~7.2Ma的全球气候变冷事件.因此,光谱参数可作为反映区域和全球气候变化的古环境指标.

关键词：可见光/近红外光谱短波红外光谱古气候指标红黏土青藏高原

Approximate Augmented Lagrangian Functions and Nonlinear Semidefinite Programs

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Acta Mathematica Sinica,English Series 2006年第5期22卷 1283-1296页

作者： x.x.HUANG K.L.TEO x.Q.YANG School of Management Fudan University Shanghai 200433 P. R. China and Department of Mathematics and Computer Science Chongqing Normal UniversityChongqing 400047 P. R. China Department of Mathematics and Statistics Curtin University of Technology Perth Australia Department of Applied Mathematics The Hong Kong Polytechnic UniversityKowloon Hong Kong P. R. China

In this paper, an approximate augmented Lagrangian function for nonlinear semidefinite programs is introduced. Some basic properties of the approximate augmented Lagrange function such as monotonicity and convexity are discussed. Necessary and sufficient conditions for approximate strong duality results are derived. Conditions for an approximate exact penalty representation in the framework of augmented Lagrangian are given. Under certain conditions, it is shown that any limit point of a sequence of stationary points of approximate augmented Lagrangian problems is a KKT point of the original semidefinite program and that a sequence of optimal solutions to augmented Lagrangian problems converges to a solution of the original semidefinite program.

关键词： semidefinite programming augmented Lagrangian duality exact penalty convergence,stationary point

FINITE ELEMENT ANALYSIS OF VISCOUS FLOW PAST A rOTATING SPHErE

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Journal of Hydrodynamics 2001年第2期13卷 80-85页

作者： Wang, Y.x. Lu, x.Y. Zhuang, L.x. Dept. of Modern Mech. Univ. of Sci. and Technol. of China Hefei 230026 China

Viscous flow past a rotating sphere with a constant rotating speed about an axis aligned with the free stream was investigated numerically by solving the three-dimensional Navier-Stokes equations using the finite element method. To elucidate the character of this flow in the near wake, the flow structures at different reynolds numbers and rotating speeds are examined. The axisymmetric and non-axisymmetric flow structures were observed at re=200 and 250, respectively, which rotate as a whole around the rotating axis steadily. At re=300, the vortex shedding appears and the wake becomes more complicated. At low rotating speeds, the flow is dominated by the vortex shedding at higher reynolds numbers. As the rotating speed increases, the rotating effect gets stronger and the interaction between the rotating action and the vortex shedding results a swirling vortex pattern in the near wake of the sphere.

关键词： Finite element method Navier Stokes equations Numerical methods Three dimensional