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Structural evolution of Al–8%Si hypoeutectic alloy by ultrasonic processing

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journal of Materials Science & Technology 2017年第11期33卷 1235-1239页

作者： j.Y.Wang B.j.Wang l.f.Huang Department of Applied Physics Northwestern Polytechnical University Xi'an 710072 China

High intensity power ultrasound was respectively introduced into three different solidification stages of Al–8%Si hypoeutectic alloy, including the fully liquid state before nucleation, the nucleation and growth process of primary α（Al） phase and l →（Al）＋（Si） eutectic transformation period. It is found that both the primary α（Al） phase and（Al ＋ Si） eutectic structure were refined by different degrees with various growth morphologies depending on the ultrasonic treatment stage. Based on the experimental results,the cavitation-induced nucleation due to the high undercooling caused by the collapse of tiny cavities was proposed as the major reason for refining the primary α（Al） phase. Meanwhile, obvious eutectic morphological change was observed only when ultrasound was directly introduced in the eutectic transformation stage, in which typical divorced eutectics and（Al ＋ Si） eutectic cells with symmetrical flower shape were formed at the top of the alloy sample. The introduction of ultrasound in each solidification stage also improves the yield strength of Al–8% Si alloy to a diverse extent.

关键词： Solidification Microstructure Metals and alloys Power ultrasound Refinement

Merging bound states in the continuum in an open acoustic resonator

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Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 124-131页

作者： lujun Huang Bin jia Artem S.Pilipchuk Sibo Huang Chen Shen Almas f.Sadreev Yong li Andrey E.Miroshnichenko School of Physics and Electronic Sciences East China Normal University Institute of Acoustics Tongji University l.V.Kirensky Institute of Physics Department of Mechanical Engineering Rowan University School of Engineering and Technology University of New South Wales at Canberra

Bound states in the continuum （BICs） are perfectly localized resonances despite embedding in the continuum ***,an isolated BIC is very sensitive to the structure ***,we report merging acoustic BICs in a single open resonator,robust against the structure *** find that both symmetry-protected BIC and friedrich-Wintgen BIC are sustained in a single coupled waveguide-resonator *** varying the height and length of the resonator,these two BICs move toward each other and merge into a single one at a critical *** to an individual BIC,the merged BIC is robust against fabrication error because its Q-factor is proportional to Δl-4,whereΔl embodies the structure *** essence of this extraordinary phenomenon is perfectly explained by the two-and three-level approximations of the effective nonHermitian ***,we present direct experimental demonstrations of the moving and merging of BICs in a coupled 3D waveguide-resonator,which are evidenced by the vanishing of the linewidth of fano resonance in the transmission *** results may find exciting applications in designing high-quality acoustic sources,sensors and filters.

关键词： acoustic resonances bound state in the continuum high-Q resonances

PHOTOCURING STUDY Of NEW DENTAl RESINS BASED ON MUlTIfUNCTIONAl ACRYlIC ISOCYANURATE BY PHOTOCAlORIMETRY

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Chinese journal of Polymer Science 1999年第5期17卷 411-415页

作者：聂俊 l.A.linden j.f.Rabek Institute of Photographic Chemistry Chinese Academy of Sciences Beijing 100101 China Department of Dental Biomaterials Science Karolinska Institute S14104 Huddinge Stockholm

Photocuring of new dental resins composed of tri(2-hydroxyethyl) isocyanurate triacrylate (THITA) alone and its mixtures with trimethylolpropane triacrylate (TMPTA) or pentaerythritol triacrylate (PETA) initiated by camphorquinone/amine system was studied by photocalorimetry. Among several different amines as coinitiators, 2-ethyl-4-dimethylaminobenzoate (AM-3), N,N-dimethylbenzylamine (AM-5) and 2,4,6-[tri(dimethylaminomethyl)]phenol (AM-6) are most effective. Upon irradiation, photopolymerization can occur immediately and no induction period appears in N-2 nor in air. Comparing the THITA/TMPTA and THITA/PETA mixtures, the parameters of photopolymerization and hardness of photocured samples show a small difference and only change slightly with varying molar ratios of mixture. In the presence of inorganic filler, the hardness of photocuring resins is almost the same as that for commercial products.

关键词： multifunctional acrylates photocuring dental resin network

Trans-scale mechanics: looking for the missing links between continuum and micro/nanoscopic reality

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Acta Mechanica Sinica 2008年第2期24卷 111-126页

作者： Y.l.Bai H.Y.Wang M.f.Xia f.j.Ke State Key laboratory of Non-linear Mechanics (lNM) Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China State Key laboratory of Non-linear Mechanics (lNM) Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China Department of Physics Peking University Beijing 100871 China State Key laboratory of Non-linear Mechanics (lNM) Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China Department of Applied Physics Beihang University Beijing 100083 China

Problems involving coupled multiple space and time scales offer a real challenge for conventional frame-works of either particle or continuum mechanics. In this paper, four cases studies （shear band formation in bulk metallic glasses, spallation resulting from stress wave, interaction between a probe tip and sample, the simulation of nanoindentation with molecular statistical thermodynamics） are provided to illustrate the three levels of trans-scale problems （problems due to various physical mechanisms at macro-level, problems due to micro-structural evolution at macro/micro-level, problems due to the coupling of atoms/ molecules and a finite size body at micro/nano-level） and their formulations. Accordingly, non-equilibrium statistical mechanics, coupled trans-scale equations and simultaneous solutions, and trans-scale algorithms based on atomic/molecular interaction are suggested as the three possible modes of trans-scale mechanics.

关键词： Multi-scale Missing-links Continuum mechanics Particle mechanics Trans-scale mechanics

Deformation behaviors of Cu bicrystals with an inclined twin boundary at multiple scales

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journal of Materials Science & Technology 2017年第7期33卷 698-702页

作者： l.l.li Z.j.Zhang P.Zhang j.Tan j.B.Yang Z.f.Zhang Shenyaag National laboratory for Materials Science lastitute of Metal Research Chinese Academy of Sciences Shenyaag 110016 China

Cu bicrystals of different sizes with a sole twin boundary（TB） inclined at 45？with respect to the loading direction were deformed under unidirectional and cyclic loading, respectively. It is found that the slip bands（SBs） parallel to the TB can be activated near the TB at all scales without obeying the Schmid＇s *** is concerned with the local stress enhancement in the macroscale while it is more closely related to the scarce dislocation sources in the microscale. Moreover, a wedge-shaped zone formed near the TB in the microscale ascribed to the limited specimen size.

关键词： Bicrystal Micropillar Twin boundary Schmid factors Size effect

Carbon isotopes of graphite:Implications on fluid history

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Geoscience frontiers 2012年第2期3卷 197-207页

作者： f.j.luque E.Crespo-feo j.f.Barrenechea l.Ortega Departamento de Cristalografía y Mineralogía facultad de Geología Universidad Complutense de Madrid 28040 MadridSpain Instituto de Geociencias(UCM-CSIC) Jos Antonio Novais 228040 MadridSpain Departamento de Cristalografia y Mineralogia facultad de Geología Universidad Complutense de Madrid28040 MadridSpain Departamento de Cristalografía y Mineralogía facultad de Geología Universidad Complutense de Madrid28040 MadridSpain

Stable carbon isotope geochemistry provides important information for the recognition of funda- mental isotope exchange processes related to the movement of carbon in the lithosphere and permits the elab- oration of models for the global carbon cycle. Carbon isotope ratios in fluid-deposited graphite are powerful tools for unravelling the ultimate origin of carbon （organic matter, mantle, or carbonates） and help to constrain the fluid history and the mechanisms involved in graphite deposition. Graphite precipitation in fluid-deposited occurrences results from C02- and/or CH4-bearing aqueous fluids. fluid flow can be considered as both a closed （without replenishment of the fluid） or an open system （with renewal of the fluid by successive fluid batches）. In closed systems, carbon isotope systematics in graphite is mainly governed by Rayleigh precipi- tation and/or by changes in temperature affecting the fractionation factor between fluid and graphite. Such processes result in zoned graphite crystals or in successive graphite generations showing, in both cases, isotopic variation towards progressive 13C or 12C enrichment （depending upon the dominant carbon phase in the fluid, C02 or CH4, respectively）. In open systems, in which carbon is episodically introduced along the fracture systems, the carbon systematics is more complex and individual graphite crystals may display oscillatory zoning because of Rayleigh precipitation or heterogeneous variations of 613C values when mixing of fluids or changes in the composition of the fluids are the mechanisms responsible for graphite precipitation.

关键词： Graphite Carbon isotopes Crust C-O-H fluids

Multimodal probe for optical coherence tomography epidetection and micron-scale indentation

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journal of Innovative Optical Health Sciences 2017年第6期10卷 64-72页

作者： l.Bartolini f.feroldi j.j.A.Weda M.Slaman j.f.de Boer D.Iannuzzi Department of Physics and Astronomy Vrije Universiteit Amsterdam and laserlab Amsterdam de Boelelaan 1081 1081HV AmsterdamThe Netherlands

We present a multimodal ferrule-top sensor designed to perform the integrated epidetection of Optical Coberence Tomognphy(OCT)depth-profiles and micron-scale indentation by all-optical *** scarning a sample under the probe,we can obtain structural crosse soction images and identify a region of interest in a nonhomogencous ***,with the same probe and setup,we can immediately target that area with a series of spherical indentation measurements,in which the applied load is known with aμN precision,the indentation depth with sub-/m precision and a maximum contact radius of 100 *** to the visualization of the internal structure of the sample,we can gain a better insi ght into the observed mechanical *** ability to impart a small,confined load,and perfomn OCT A scans at the same time,could lead to an altemative,high transverse resolution,Optical Coherence Elastography(OCE)sensor.

关键词： Optomechanical microindentation optical coherence tomography indentation multimodal sensor,epidetection

fORMATION Of fe-N COMPOUNDS BY lASER NITRIDATION IN AN ATMOSPHERIC AMBIENT

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Acta Metallurgica Sinica(English letters) 2003年第2期16卷 139-144页

作者： Y.l.Yang f.j.Sun D.Zhang College of Science Northeastern UniversityShenyang 110004ChinaCollege of ScienceNortheastern UniversityShenyang 110004ChinaCollege of ScienceNortheastern UniversityShenyang 110004China

The formation of fe-N compounds by laser nitriding in an atmospheric ambient was reported. By CW-CO2 laser irradiation on pure ferrite iron in the atmospheric ambient, fe-N compounds (including fe2N, .fe3AT and fe4N) are formed as a result of a laser-enhanced and temperature-enhanced reactions. The samples were analyzed with X-ray diffraction. It is found that the laser power density, scanning speed and nitrogen temperature are the main factors influencing the formation of fe-N compounds. Nitrogen can be activated by pre-heating at some temperature. Nitrogen activation and sample surface melting by CW-CO2 laser greatly enhance the reaction between the sample surface and nitrogen beam. After annealing at 500℃for 3h, some fe2N and fe3N converted into more stable fe4N.

关键词： laser nitriding nitride fe-N compound

Drivability of large Diameter Steel Cylinders During Hammer-Group Vibratory Installation for the Hong Kong–Zhuhai–Macao Bridge

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Engineering 2023年第1期20卷 180-191页

作者： W.j.lu B.li j.f.Hou X.W.Xu H.f.Zou l.M.Zhang Department of Civil and Environmental Engineering The Hong Kong University of Science and TechnologyKowloonHong Kong 999077China The Hong Kong University of Science and Technology Shenzhen Research Institute Shenzhen 518057China Tianjin Port Engineering Institute Co. Ltd.of CCCC First Harbor Engineering Co.Ltd.Tianjin 300222China Key laboratory of Port Geotechnical Engineering Ministry of Communications of People’s Republic of ChinaTianjin 300222China CCCC first Harbor Engineering Company ltd. Tianjin 300461China AECOM Asia Company limited Hong Kong 999077China

The Hong Kong–Zhuhai–Macao Bridge(HZMB)involved the installation of 120 mega-cylinders with a diameter of 22 m,weights up to 513 t,and penetration depths up to 33 m using an eight-vibratory hammer *** to the lack of engineering experience on the drivability of large-diameter cylinders under multiple vibratory hammers,predicting the penetration rate and time of steel cylinders is an open challenge that has a considerable impact on the construction control of the *** this study,the vibratory penetration of large-diameter steel cylinders in the HZMB is investigated based on geological surveys,field monitoring,and drivability *** vibratory penetration rate,installation accuracy,and dynamic responses of the steel cylinders at both the eastern and western artificial islands are *** dynamic soil resistance has a great influence on the cylinder ***,the current design methods for estimating the vibratory driving soil resistance are proven inaccurate without considering the scale ***,a modified method with a normalized effective area ratio A_(r,eff)is proposed in this study to calculate the vibratory soil resistance for open-ended thin-wall cylinders under unplugged *** the scale effects on the vibratory driving soil resistance,the proposed method leads to closer results to the measured data,providing a reference for future engineering practice.

关键词： Hong Kong-Zhuhai-Macao Bridge Vibratory pile driving Wave equation analysis large-diameter steel cylinder Artificial island offshore foundati ons