检索结果-南通市图书馆

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

在线全文

学校读者我要写书评

暂无评论

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

Cortical hem signaling center: functions, development, and potential implications for evolution and brain disorders

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第4期20卷 1079-1080页

作者： Victor V.Chizhikov Igor y.Iskusnykh Department of Anatomy and Neurobiology University of Tennessee Health Science CenterMemphisTNUSA

Development of the telencephalon relies upon several signaling centers-localized cellular populations that supply secreted factors to pattern the cortical *** such signaling center is the cortical hem,which arises during embryonic development at the telencephalic dorsal midline,adjacent to the choroid plexus and hippocampal primordium(Figure 1A).While the cortical hem has also been described in reptiles and birds,most of our knowledge about the developmental roles of the cortical hem is derived from the analysis in *** cortical hem produces several types of secreted molecules,including wingless-related integration site(Wnt)and bone morphogenetic(Bmp)*** cortical hem is particularly important for the development of the hippocampus,which is involved in learning and memory,and the neocortex,which is the most complex brain region that mediates multiple types of behavior and higher cognitive functions(mangale et al.,2008;Dal-Valle-Anton and Borrell,2022).

关键词： epithelium Figure center

Hard yet tough and self-lubricating(CuNiTiNbCr)C_(x) high-entropy nanocomposite films:Effects of carbon content on structure and properties

在线全文

学校读者我要写书评

暂无评论

Journal of materials Science & Technology 2024年第6期173卷 20-30页

作者： y.T.Li x.m.Chen x.K.Zeng m.Liu x.Jiang y.x.Leng Key Laboratory of Advanced Technologies of materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China Key Laboratory of Noise and Vibration Research Institute of AcousticsChinese Academy of SciencesBeijing 100190China State Key Laboratory of Acoustics Institute of AcousticsChinese Academy of SciencesBeijing 100190China School of mechanical and Electrical Engineering Mianyang Teachers’CollegeMianyang 621000China

The single-phase high-entropy alloy film is difficult to meet severe friction conditions due to its low hardness and high friction ***-composite structure film is composed of at least two separated phases,showing the properties of strength and toughness integration and excellent wear *** design of nanocomposite structures can effectively improve the mechanical properties and tribological properties of high-entropy alloy *** this study,the(CuNiTiNbCr)C_(x) nanocomposite high-entropy films(HEFs)integrated with high hardness,high toughness,and self-lubrication were synthesized by the double-target co-sputtering *** effect of carbon content on microstructure,mechanical properties,and tribological properties of(CuNiTiNbCr)C_(x) films was *** the increase of carbon content in the HEFs,the carbon atoms preferentially react with Ti,Nb,and Cr to form a(TiNbCr)C ceramic-reinforced phase,and then the excess carbon atoms precipitate in the form of amorphous carbon(a-C)lubricating phase in the *** structure of the HEFs changes from an amorphous structure to a nanocomposite structure of amorphous(amorphous CuNiTiNbCr phase+a-C phase)/nanocrystalline(TiN-bCr)C *** the carbon content is about 21.2 at.%,the carbide phase in the film reaches saturation and the hardness and modulus of the films are highest,which are 18 GPa and 228 GPa,*** HEFs with a carbon content of 44.0 at.%show the best toughness and tribological properties with a friction coefficient of 0.16 and a wear rate of 2.4×10^(-6) mm^(3)/(N m),which is mainly attributed to the excellent resistance to fatigue crack growth and the interfacial lubricating layer formed in the friction *** nanocomposite(CuNiTiNbCr)C_(x) HEFs show very promising application prospect in the field of friction protection.

关键词： High-entropy films Nanocomposite Double-target co-sputtering Strengthening-toughening Tribological properties

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

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

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

Species limits in the Elegant Pitta (Pitta elegans) complex from Wallacea based on bioacoustic and morphometric analysis

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Avian Research 2020年第4期11卷 421-432页

作者： Arya y.yue Elize y.x.ng James A.Eaton Frank E.Rheindt Bryn mawr College Department of Biology101 N Merion AveBryn MawrPA 19010USA Department of Biological Sciences National University of Singapore16 Science Drive 4Singapore 117558Singapore A-3A-5 Casa Indah IPersiaran Surian47810 Petaling JayaMalaysia

Background:The Elegant Pitta(Pitta elegans)complex displays a remarkable diversity of morphological and bioacoustic traits across five taxa currently recognized as *** differ in plumage characteristics(such as red versus black belly patches;supercilium color and extent;and white versus black throats),in lifestyle(resident versus migratory)and in *** investigated the morphological,bioacoustic and ecological differences across all taxa after recent studies demostrated the importance of these traits in recognizing biological species limits across ***:morphometric analysis was carried out by measuring tarsus,wing,tail and bill lengths of 15 specimens at the Natural History museum,UK,and plumages were inspected across 106 unique individuals from four different *** analysis was based on 134 range-wide sound *** types of calls,territorial calls and alarm calls,were analyzed using different sets of *** component analysis and the Isler Criterion were applied to the *** trials were conducted to explore the levels of response of each taxon to the call types of the other ***:The territorial call of concinna exhibits a distinct two-element motif,while elegans,maria and virginalis utter a three-element motif in which the first two elements are given in quick *** the other hand,vigorsii,produces both two-element and three-element motifs with longer breaks in between *** further corroborated by the playback trials,the three taxa elegans,virginalis and maria form a tight vocal cluster,whereas each concinna and vigorsii are *** alarm call turned out to be less diagnostic even though most taxa did roughly separate into different vocal *** analysis failed to produce strong differences,but plumage distinctions among multiple taxa are ***:We suggest splitting the Elegant Pitta into three biological species based on

关键词： Bioacoustic analysis Elegant Pitta morphometric analysis Pitta elegans Territorial calls

Effect of perforation on flow past a conic cylinder at Re =100: wavy vortex and sign laws

在线全文

学校读者我要写书评

暂无评论

Acta mechanica Sinica 2018年第5期34卷 812-829页

作者： L.m.Lin x.F.Zhong y.x.Wu Key Laboratory for mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Sciences University of Chinese Academy of SciencesBeijing 100049China

In order to find the intrinsic physical mechanism of the original Kármán vortex wavily distorted across the span due to the introduction of three-dimensional (3-D) geometric disturbances,a flow past a peak-perforated conic shroud is numerically simulated at a Reynolds number of *** on previous work by meiburg and Lasheras (1988),the streamwise and vertical interactions with spanwise vortices are introduced and *** vortex-shedding patterns in the near wake for different flow regimes are reinspected and illustrated from the view of these two ***,in regime Ⅰ,spanwise vortices are a little distorted due to the weak *** in regime Ⅱ,spanwise vortices,even though curved obviously,are still shed synchronously with moderate streamwise and vertical *** in regime Ⅲ,violently wavy spanwise vortices in some vortex-shedding patterns,typically an Ω-type vortex,are mainly attributed to the strong vertical interactions,while other cases,such as multiple vortex-shedding patterns in sub-regime Ⅲ-D,are resulted from complex streamwise and vertical interactions.A special phenomenon,spacial distribution of streamwise and vertical components of vorticity with specific signs in the near wake,is analyzed based on two models of streamwise and vertical vortices in explaining physical reasons of top and bottom shear layers wavily varied across the *** these two models and above two interactions are *** two sign laws are summarized:the first sign law for streamwise and vertical components of vorticity is positive in the upper shear layer,but negative in the lower shear layer,while the second sign law for three vorticity components is always negative in the wake.

关键词： Vortex-shedding pattern Flow control Vortex dynamics Conic disturbance Perforation Sign law

mechanism of wavy vortex and sign laws in flow past a bluff body:vortex-induced vortex

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta mechanica Sinica 2019年第1期35卷 1-14,I0001页

作者： L.m.Lin S.y.Shi x.F.Zhong y.x.Wu Key Laboratory for mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Sciences University of Chinese Academy of SciencesBeijing 100049China

As reported in a previous work by Lin et al.(Acta meeh Sin, 2018. https://***/10.1007/s 10409-018-0758-z), an interesting phenomenon was discovered based on the analysis of wavy vortex and vorticity distribution in the shear layers and near wake of a peak-perforated conic shroud, and two sign laws were summarized. In the present paper, the theory of a vortex-induced vortex is introduced to explore mechanisms in a wavy vortex and applicable sign laws for uniform and incompressible flow past a fixed bluff body. Based on the analysis of the nearest-wall How, two vortex-induced models for streamwise and vertical vortex pairs, respectively, are proposed under two boundary cases, denoting the induced vorticity introduced or distributed on and near the walls. As a result, the first sign law, for only streamwise and vertical components of vorticity, and the second sign law, for three components of vorticity, are obtained under their own particular conditions. The first sign law reveals the intrinsic physical relationship between streamwise and vertical vorticities, independent of the distribution of spanwise vortices in the whole flow field. It is also confirmed that the spanwise vortices, as well as the shear layers and wake width, distributed wavily across the span, are attributed to the introduced streamwise or vertical vortices. The two sign laws for vorticity are independent of the disturbed spanwise wavelength and the Reynolds number. Through the analysis of flow past the conic shroud, the two sign laws are successfully used to summarize typical spacial distributions of vorticity in three flow regions: on and near the front cylinder surfaces, the separated shear layers and the near wake.

关键词： Wavy vortex Sign law Vortex-induced vortex Wake Bluff body

Effect of perforation on flow past a conic cylinder at Re=100:vortex-shedding pattern and force history

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta mechanica Sinica 2018年第2期34卷 238-256页

作者： L.m.Lin x.F.Zhong y.x.Wu Key Laboratory for mechanics in Fluid Solid Coupling Systems Institute of Mechanics Chinese Academy of Sciences

The flow past a circular-section cylinder with a conic shroud perforated with four holes at the peak was simulated numerically at Re = 100, considering two factors, *** angle of attack and the diameter of the holes. The effects of the perforated conic shroud on the vortex shedding pattern in the near wake was mainly investigated, as well as the time history of the drag and lift forces. In the investigated parameter space, three flow regimes were generally identified, corresponding to weak, moderate, and strong disturbance *** regime I, the wake can mainly be described by alternately shedding Kármán or Kármán-like vortices. In regime II, the spanwise vortices are obviously disturbed along the span due to the appearance of additional vorticity components and their interactions with the spanwise vortices, but still shed in synchronization along the spanwise direction. In regime III,the typical Kármán vortices partially or totally disappear,and some new vortex shedding patterns appear, such as-type, obliquely shedding, and crossed spanwise vortices with opposite sign. Corresponding to these complex vortex shedding patterns in the near wake, the fluid forces no longer oscillate regularly at a single vortex shedding frequency, but rather with a lower modulation frequency and multiple amplitudes. An overview of these flow regimes is presented.

关键词： Vortex shedding pattern Fluid forces Flow control Conical shroud Perforation

RATIONAL GENERAL SOLUTIONS OF HIGHER ORDER ALGEBRAIC ODES

在线全文

学校读者我要写书评

暂无评论

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.