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Robust interface and excellent as-built mechanical properties of Ti–6Al–4V fabricated through laser-aided additive manufacturing with powder and wire

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International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 154-168页

作者： fei Weng Guijun Bi Youxiang Chew Shang Sui Chaolin Tan Zhenglin Du Jinlong Su fern Lan ng Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials Ministry of EducationShandong Engineering&Technology Research Center for Superhard MaterialSchool of Materials Science and EngineeringShandong UniversityJinan 250061China Institute of Intelligent Manufacturing Guangdong Academy of SciencesGuangzhou 510095China Singapore Institute of Manufacturing Technology 5 Cleantech Loop636732Singapore

The feasibility of manufacturing Ti-6Al-4V samples through a combination of laser-aided additive manufacturing with powder(LAAM_(p))and wire(LAAM_(w))was explored.A process study was first conducted to successfully circumvent defects in Ti-6Al-4V deposits for LAAM_(p) and LAAM_(w),*** the optimized process parameters,robust interfaces were achieved between powder/wire deposits and the forged substrate,as well as between powder and wire *** characterization results revealed the epitaxial prior β grains in the deposited Ti-6Al-4V,wherein the powder deposit was dominated by a finerα′microstructure and the wire deposit was characterized by lamellar α *** mechanisms of microstructure formation and correlation with mechanical behavior were analyzed and *** mechanical properties of the interfacial samples can meet the requirements of the relevant Aerospace Material Specifications(AMS 6932)even without post heat *** fracture occurred within the interfacial area,further suggesting the robust *** findings of this study highlighted the feasibility of combining LAAM_(p) and LAAM_(w) in the direct manufacturing of Ti-6Al-4V parts in accordance with the required dimensional resolution and deposition rate,together with sound strength and ductility balance in the as-built condition.

关键词： laser-aided additive manufacturing powder deposition wire deposition interfacial characteristic mechanical behavior

Calibration of the Solar x-ray Detector on-board the Macao Science Satellite-1B for Soft x-ray Detection

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Science China Earth Sciences 2025年第1期68卷 11-26页

作者： Man-Hei ng xiaoping ZHAng Jianwu CHEN Yongqiang SHI fuchang ZUO Wenxi PEng Weichun fU Liansheng LI Pengwei LUO Chi-Long TAng Guozheng ZHAng Zhiwu MEI Li WAng Cunhui LI Jiaming OU Yanyan xU State Key Laboratory of Lunar and Planetary Sciences Macau University of Science and Technology China National Space Administration (CNSA) Macau Center for Space Exploration and Science Space Optoelectronic Measurement and Perception Laboratory Beijing Institute of Control Engineering Institute of High Energy Physics Chinese Academy of Sciences Science and Technology on Vacuum Technology and Physics Laboratory Lanzhou Institute of Physics

The Solar x-ray Detector(SxD) on-board the Macao Science Satellite-1B(MSS-1B) was successfully launched via the Chinese Long March-2C rocket on 21 May 2023, and commenced operations in early June of the same year. The MSS-1B/Soft x-ray Detection Units(SxDUs) employ two silicon drift detectors(SDDs), providing a wide range of energy spectra spanning from 0.7 to 24 keV. Notably, the SxDUs deliver a high-resolution capability of 0.14 keV@5.9 keV and operate with a time cadence of 1 second. Here, we perform thorough calibrations of the MSS-1B/SxDUs, employing a combination of ground experiments and simulations. In addition, quantitative analysis comparing the flux measurements obtained by the MSS-1B/SxDUs to the data collected by the Geostationary Operational Environmental Satellite(GOES), provides compelling evidence of their consistency. furthermore, the preliminary spectral analysis results showcase the robustness and expected performance of the MSS-1B/SxDUs, unlocking their potential for facilitating the study of dynamic evolution of solar flares. Moreover, the innovative MSS-1B/Solar x-ray Detector facilitates concurrent observations of solar soft and hard x-rays, thereby making valuable contributions to the advancements in solar research.

关键词： Macao Science Satellite-1B (MSS-1B) Calibration Solar x-Ray Detector Spectrometer Soft x-rays Solar flares Solar abundances

The role of AVDR in linear cascade testing

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航空动力学报 2007年第6期22卷 933-944页

作者： Wing f.ng Department of Mechanical Engineering Virginia Polytechnic Instituteand State University

Linear cascade testing plays an important role in the research and development of turbomachinery and is widely used over the *** ideal cascade model of a turbomachinery blade row is *** actual linear cascade testing,the flow through the test section converges due to the development of the boundary layer and secondary flow along the sidewall surfaces of the test *** velocity density ratio(AVDR) is adopted to account for the deviation of the tested cascade flow from the ideal 2D *** numerous published cascade works,the influence of AVDR on cascade performance is seen to be complicated with many affecting factors,such as those related to cascade/blade geometry and flow ***,controlling AVDR is limited by the facility ***,real blade-to-blade flow in turbomachines is usually associated with AVDR greater than unity due to limited span of blades between the hub and shroud such that cascade testing without reducing AVDR could be favored *** these facets add complexity and diversification to the *** current paper reviews previous studies and results on *** understanding on the role of AVDR and recommendations on how to deal with it in linear cascade testing are provided.

关键词：线性叶栅试验轴向速度密度比空气流动叶栅特性

RATIONAL GENERAL SOLUTIONS Of HIGHER ORDER ALGEBRAIC ODES

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Journal of Systems Science & Complexity 2013年第2期26卷 261-280页

作者： HUAng Yanli ng L x Chu WINKLER franz School of Computer Science and Software Engineering Tianjin Polytechnic University Research Institute for Symbolic Computation(RISC) Johannes Kepler University Department of Mathematics Quy Nhon University

This paper generalizes the method of ng6 and Winkler （2010, 2011） for finding rational general solutions of a first order non-autonomous algebraic ordinary differential equation （AODE） to the case of a higher order AODE, provided a proper parametrization of its solution hypersurface. The authors reduce the problem of finding the rational general solution of a higher order AODE to finding the rational general solution of an associated system. The rational general solutions of the original AODE and its associated system are in computable 1-1 correspondence. The authors give necessary and sufficient conditions for the associated system to have a rational solution based on proper reparametrization of invariant algebraic space curves. The authors also relate invariant space curves to first integrals and characterize rationally solvable systems by rational first integrals.

关键词： Algebraic ODE associated system invariant algebraic space curve rational first integral rational general solution.

Second-order optimality conditions f or minimizing a maxfunction

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Science China Mathematics 2000年第7期43卷 722-733页

作者：黄力人 K.f.ng Department of Mathematics South China Normal University Guangzhou 510631 China Department of Mathematics The Chinese University of Hong KongHong KongChina Correspondence should be addressed to K.F.Ng

We study Chaney's and Ben-Tal-Zowe's second-order directional derivatives with applications in minimization problem for max-functions of the formh(x): = max {f(x, τ); τ ∈T},where T is a compact metricspace. We impr... 详细信息

关键词： max-f unction sup-type function second-order optimality condition nonsmooth optimization.

Stabilizing nanograined fe-Cr alloy by Si-assisted grain boundary segregation

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Journal of Materials Science & Technology 2023年第3期134卷 223-233页

作者： x.f.xu x.Y.Li B.Zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China

Intentional solute segregation at grain boundary(GB)can effectively stabilize the nanograined alloys by reducing the excess energy and mobility of GB,but it usually works for binary alloys with sufficient GB segregation ***,we found that the segregation of Cr can be enhanced in a nanostruc-tured fe-8Cr alloy with insufficient GB segregation tendency through the interaction of another solute Si(1.0 wt.%).After surface mechanical grinding treatment and subsequent annealing,the nanograined fe-8Cr-1Si is more thermally stable than the nanograined fe-8Cr,which is mainly attributed to the Si-enhanced Cr segregation as observed by Super-x energy-dispersive x-ray spectroscopy(EDS)mapping *** the grain refinement to nanoscale,the thermal stability is further improved due to the in-crease of Cr content at GBs and the precipitates formed at appropriate high *** present finding provides guidance for the development of advanced nanostructured ternary alloys.

关键词： Segregation Grain boundary fe-Cr-Si alloy Nanocrystalline Thermal stability

finite element simulation of elastoplastic fieldnear crack tips and results for a central crackedplate of le-lhp material under tension

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Acta Mechanica Sinica 2019年第4期35卷 828-838页

作者： x. Ji f. Zhu School of Aerospace Engineering and Applied Mechanics Tongji University Shanghai 200092 China

The elastoplastic field near crack tips is investigated through finite element simulation.A refined mesh model near the crack tip is proposed. In the mesh refining area, element size continuously varies from the nanometer scale to themicrometer scale and the millimeter scale. Graphics of the plastic zone, the crack tip blunting, and the deformed crack tip elements are given in the *** on the curves of stress and plastic strain, closely near the crack tip, the stresssingularity index and the stress intensity factor,as well as the plastic strain singularity index and the plastic strain intensity factor are *** and plastic strainsingular index vary with the load, while the dimensions of the stress and the plastic strain intensity factorsdependon the stress and the plastic strain singularity index, respectively. The singular field near the elastoplastic crack tip is characterized by the stress singularity index and the stress intensity factor, or alternativelythe plastic strain singularity index and the plastic strain *** the end of the paper, following Irwin’s concept of fracture mechanics,σδKσδKcriterion andεδQεδQcriterion are ***, crack tip angle criterion is also presented.

关键词： Crack fracture mechanics Elastoplasticity finite element method Geometry Nonlinearity

Cooling Augmentation with Microchanneled Structures

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Journal of Thermal Science 1993年第2期2卷 98-110页

作者： x.f.Peng B.x.Wang ThermalEngineeringDepartment TsinghuaUniversityBeijing100084China ThermalEngineeringDepartment Tsin

Experiments were conducted to investigate the heat transfer characteristics and cooling performance of subcooled liquid, water, flowing through rectangular cross-section microchanneled structures machined on a stainless steel plate. Heat transfer or flow mode transition was observed when the heating rate or wall temperature was increased. This transition was found to be suggestively induced by the variation in liquid thermophysical properties due to the significant rise of liquid temperature in the microstructures. The influence of such parameters as liquid velocity, subcooling, property variation, and microchannel geometric configuration on the heat transfer behavior, cooling performance and the heat transfer and liquid flow mode transition were also investigated. The experiments indicated that both slngle-phase forced convection and flow boiling characteristics were quite different from those in normal-sized tubes and the heat transfer was obviously intensified.

关键词： heat transfer convection flow boiling microchanneled structure cooling

BEHAVIOR Of SHORT fATIGUE CRACKS AT BLUNT NOTCHES IN A MEDIUM CARBON STEEL

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Acta Metallurgica Sinica(English Letters) 1997年第5期10卷 430-436页

作者： Wu, Z.x. Sun, x.f. Southwest Jiaotong Univ Chengdu China

The behavior of part-through and through short cracks in single edge blunt notched specimens of a medium carbon steel was investigated by a replication method. It is found that the fatigue failure of these notched specimens is caused mainly by the growth of short surface cracks originating from the surface of notch root. More than 70% of the fatigue life is spent in the regimes in which short surface cracks initiate and propagate as part-through cracks before joining up to form a single through-thickness crack. The effect of original crack profile which is formed through the coalescence of multiple part-through cracks is the main reason causing the 'anomalous' propagation behavior of the through-thickness crack in its early stage.

关键词： Carbon steel Crack initiation Crack propagation fatigue of materials fracture mechanics Surfaces