检索结果-南通市图书馆

STRUCTURAL DETERMINATION OF TITANIUM-OXIDE NANOPARTICLES By.X-RAy.ABSORPTION SPECTROSCOPy

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2002年第1期15卷 53-57页

作者： Z.y. Wu J. Zhang K. Ibrahim M.I. Abbas G. Li y. Tao T.D. hu F.Q. Liu H.J. Qian y.N. Xie Q.H. Zhang L. Gao Z.Z. Chen Beijing Sy.chrotron Radiation Facility Institute of High Energy PhysicsThe Chinese Academy of SciencesBeijing 100039China Laboratori Nazionali di Frascati Istituto Nazionali di Fisica Nucleare Via Enrico Fermi 40P.O. Box 13I-00044 FrascatiItaly Beijing Sy.chrotron Radiation Facility Institute of High Energy PhysicsThe Chinese Academy of Sciences Beijing 100039China Shanghai Institute of Ceramics The Chinese Academy of SciencesShanghai200050China

As a potential application of titanium-oxide nanoparticles, it is extremely.important to investigate a detailed picture of the surface and interior structural properties of nanocry.talline materials, such as rutile and anatase with diameters 7.0 and 4.5nm, respectively. X-ray.absorption spectroscopy.has been used to identify.the local Ti environment and related electronic structure. We combine the experimental results at the Ti edge in both bulk and nano-cry.tals to determine the lattice distortion in terms of differently.characteristic preedge features and the variation in the multiple-scattering region of X-ray.absorption near-edge structure (XANES) spectra. The relationship between the transition peaks and the surface-to volume ratio is also discussed.

关键词： X-ray.absorption near edge structure nano particle transition metal oxide

The contrast between defect solitons in parity.time sy.metric superlattice and simple-lattice complex potentials

在线全文

学校读者我要写书评

暂无评论

Chinese Phy.ics B 2012年第2期21卷 362-367页

作者： hu Su-Mei hu Wei Laboratory.of Photonic Information Technology South China Normal UniversityGuangzhou 510631China Department of Phy.ics Guangdong University of Petrochemical TechnologyMaoming 525000China

The existence and stability.of defect superlattice solitons in parity.time （PT） sy.metric superlattice and simplelattice complex potentials are reported. Compared with defect simple-lattice solitons in similar potentials, the defect soliton in superlattice has a wider stable range than that in simple-lattice. The solitons＇ power increases with increasing propagation constant. For the positive defect, the solitons are stable in the whole region where solitons exist in the semi-infinite gap. For the zero defect, the solitons are unstable at the edge of the band. For the negative defect, the solitons propagate with the shape of y.at low propagation constant and propagate stably.at the large one.

关键词： defect superlattice solitons parity.time sy.metry

Two New Triterpenoid Saponins from Aster Lingulatus

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1996年第11期7卷 1005-1008页

作者： hu, B Shao, y.Qin, GW Ho, CT Chin, CK Rosen, RT ACAD SINICA SHANGHAI INST MAT MEDSHANGHAI 200031PEOPLES R CHINA RUTGERS STATE UNIV COOK COLLNEW BRUNSWICKNJ 08903

Two new saponins named asterlingulatosides A and B were isolated from the whole plants of Aster lingulatus. Their structures were elucidated by.spectral and chemical evidence as 3-O-beta-D-glucopy.anosy.-3 beta, 16 alpha-dihy.roxy.lean-12-en-28-oic acid -28-O-alpha-L-arabinopy.anoside and 3-O-beta-D-glucopy.anosy.-3 beta,16 alpha-dihy.roxy.lean-12-en-28-oic acid -28-O-alpha-L-rhamnopy.anosy.-(1-->2)- alpha-L-arabinopy.anoside respectively. They.showed inhibitory.activity.on DNA sy.thesis of human leukemia HL-60 cells.

关键词： Lingulatus Two New Triterpenoid Saponins from Aster

大型旋转机械摩擦学—动力学设计数据库的设计与实现

在线全文

学校读者我要写书评

暂无评论

润滑与密封 1998年第5期23卷 28-31页

作者：胡亚红刘路放谢友柏张优云西安交通大学润滑理论及轴承研究所 710049

本文针对摩擦学系统的特点,详细地研究了一类有代表性的摩擦学系统—大型汽轮发电机组转子轴承系统——的摩擦学—动力学设计数据库。说明了摩擦学—动力学设计数据库的设计过程,以及摩擦学—动力学设计数据库的结构和功能。

关键词：摩擦学摩擦学-动力学数据库旋转机械

A Polarization Programmable Antenna Array

在线全文

学校读者我要写书评

暂无评论

Engineering 2022年第9期16卷 100-114页

作者： Dingzhao Chen y.nhui Liu Ming Li Pan Guo Zhuo Zeng Jun hu y.Jay.Guo Institute of Electromagnetics and Acoustics Xiamen UniversityXiamen 361000China School of Electronic Science and Engineering University of Electronic Science and Technology of ChinaChengdu 611731China y.ngtze Delta Region Institute(Quzhou) University of Electronic Science and Technology of ChinaQuzhou 324000China Global Big Data Technologies Centre University of Technology Sydney(UTS)NSW 2007Australia

Reconfigurable antennas are becoming a major antenna technology.for future wireless communications and sensing *** is known that,with a single linear polarization(LP)reconfigurable antenna element,a preferred polarization can be produced from a set of multiple polarization states,thus improving the quality.of the communication *** paper presents a new concept of a polarization programmable reconfigurable antenna array.that consists of a number of polarization reconfigurable antenna elements with a finite number of possible polarization *** employ.ng a new optimization strategy.and programming the polarization states of all the array.elements,we demonstrate that it is possible to realize any.desired LP in the vectorial array.radiation pattern with accurate control of sidelobe and crosspolarization levels(XPLs),thereby.achieving the desired polarization to perfectly.match that of the required communications *** numerical and experimental results are provided to prove the concept,and they.agree well with each other.

关键词： Antenna array Polarization reprogrammable antenna Reconfigurable antenna

Oxidation behavior and microstructural evolution of FeCoNiTiCu five-element high-entropy.alloy.nanoparticles

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10期177卷 133-141页

作者： H.Bai R.Su R.Z.Zhao C.L.hu L.Z.Ji y.J.Liao y.N.Zhang y.X.Li X.F.Zhang Key.Laboratory.for Anisotropy.and Texture of Materials(MOE) School of Materials Science and EngineeringNortheastern UniversityShenyang110819China Institute of Advanced Magnetic Materials College of Materials and Environmental EngineeringHangzhou Dianzi UniversityHangzhou310012China

High-entropy.alloy.(HEAs)have attracted extensive attention ascribed to their unique phy.ical and chemical properties induced by.the cocktail ***,their oxidation behaviors,in particular at nanoscale,are still lack because of multi-element complexity.which could also be completely.differ-ent from the bulk *** this work,we sy.thesized FeCoNiTiCu five-element HEA nanopar-ticles(NPs)with uniform elemental distribution by.arc-discharging approach,and further investigated their oxidation behaviors at 250 ℃,and 350 ℃.The morphology.structure and element distribution of NPs were analy.ed by.transmission electron microscopy.TEM),energy.dispersive spectroscopy.EDS)and electron energy.loss spectroscopy.EELS).The surface oxidation in FeCoNiTiCu NPs during the high-temperature process can induce nanoscale pores at core/shell interfaces by.Kirkendall effect,and even the eventual coalescence into a single ***,the oxidation states of NPs with diameters(d)vary.ng from 60 to 350 nm were analy.ed in detail,revealing two ty.ical configurations:hollow(dy.lk-shell structures(d>150 nm).The experimental results were complemented by.first-principles calculations to investigate the diffusion behaviors of five elements,evidencing that the surface oxidation strongly.alters the surface segregation preferences:(1)in the initial stage,Cu and Ni appear to prefer segregating on the surface,while Co,Ti and Fe tend to stay.in the bulk;(2)in the oxidation process,Cu prefers to stay.in the center,while Ti segregates to the surface ascribed to the reduced po-tential *** study.gives new insights into oxidation of nanoscale HEA,and also provides a way.for fabrication of high-entropy.oxides with controllable architectures.

关键词： High-entropy.alloy Nanoparticles Oxidation Kirkendall effect Exchange bias effect

Einstein Probe discovery.of EP240408a: A peculiar X-ray.transient with an intermediate timescale

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(Phy.ics,Mechanics & Astronomy. 2025年第1期Mechanics & Astronomy) .卷 222-240页

作者： Wenda Zhang Weimin y.an Zhixing Ling y.ng Chen Nanda Rea Arne Rau Zhiming Cai huaqing Cheng Francesco Coti Zelati Lixin Dai Jingwei hu Shumei Jia Chichuan Jin Dongy.e Li Paul O’Brien Rongfeng Shen Xinwen Shu Shengli Sun Xiaojin Sun Xiaofeng Wang Lei y.ng bing Zhang Chen Zhang Shuang-Nan Zhang y.nghe Zhang Jie An David Buckley.Alexis Coleiro Bertrand Cordier Liming Dou Rob Ey.es-Ferris Zhou Fan hua Feng Shaoy. Fu Johan P.U.Fy.bo Lluis Galbany.Saurabh W.Jha Shuaiqing Jiang Albert Kong Erik Kuulkers Weihua Lei Wenxiong Li Bifang Liu Mingjun Liu Xing Liu y.an Liu Zhu Liu Chandrey.e Maitra Alessio Marino Itumeleng Monageng Kirpal Nandra Jeremy.Sanders Roberto Soria Lian Tao Junfeng Wang Song Wang Tinggui Wang Zhongxiang Wang Qingwen Wu Xuefeng Wu Dong Xu y.njun Xu Suijian Xue y.ngquan Xue Zijian Zhang Zipei Zhu hu Zou Congy.ng Bao Fansheng Chen Houlei Chen Tianxiang Chen Wei Chen y.hai Chen y.fan Chen Chenzhou Cui Weiwei Cui y.nfeng Dai Dongwei Fan Ju Guan Dawei Han Dongjie Hou Haibo hu Maohai huang Jia huo Zhenqing Jia Bowen Jiang Ge Jin Chengkui Li Junfei Li Longhui Li Maoshun Li Wei Li Zhengda Li Tiany.ng Lian Congzhan Liu Hey.ng Liu huaqiu Liu Fangjun Lu Laidan Luo Jia Ma Xuan Mao Haiwu Pan Xin Pan Liming Song hui Sun y.ny.n Tan Qingjun Tang y.han Tao Hao Wang Juan Wang Lei Wang Wenxin Wang y.long Wang y.sa Wang Qiny. Wu Haitao Xu Jingjing Xu Xinpeng Xu y.nfei Xu Zhao Xu Changbin Xue y.long Xue Ailiang y.n Haonan y.ng Xiongtao y.ng y.nji y.ng Juan Zhang Mo Zhang Wenjie Zhang Zhen Zhang Zhen Zhang Ziliang Zhang Donghua Zhao Haisheng Zhao Xiaofan Zhao Zijian Zhao Hongy.n Zhou y.lin Zhou y.xuan Zhu Zhencai Zhu National Astronomical Observatories Chinese Academy.of Sciences School of Astronomy.and Space Sciences University.of Chinese Academy.of Sciences Key.Laboratory.of Particle Astrophy.ics Institute of High Energy.Phy.ics Chinese Academy.of Sciences Institute of Space Sciences (ICE) CSIC Institut d’Estudis Espacials de Cataluny. (IEEC) Max Planck Institute for Extraterrestrial Phy.ics Innovation Academy.for Microsatellites Chinese Academy.of Sciences Department of Phy.ics University.of Hong Kong School of Phy.ics and Astronomy University.of Leicester School of Phy.ics and Astronomy Sun y.t-sen University Department of Phy.ics Anhui Normal University Shanghai Institute of Technical Phy.ics Chinese Academy.of Sciences Phy.ics Department Tsinghua University Nevada Center for Astrophy.ics University.of Nevada Las Vegas Department of Phy.ics and Astronomy University.of Nevada Las Vegas South African Astronomical Observatory Department of Astronomy University.of Cape Town Department of Phy.ics University.of the Free State Université Paris Cité CNRS Astroparticule et Cosmologie Université Paris Cité CEA Paris-Saclay IRFU/DAp-AIM Department of Astronomy Guangzhou University Cosmic Dawn Center (DAWN) Niels Bohr Institute University.of Copenhagen Department of Phy.ics and Astronomy Rutgers the State University.of New Jersey Institute for Cosmic Ray.Research The University.of Toky. ESA/ESTEC Department of Astronomy School of Phy.ics huazhong University.of Science and Technology INAF-Osservatorio Astrofisico di Torino Sy.ney.Institute for Astronomy School of Phy.ics The University.of Sy.ney Department of Astronomy Xiamen University Institute for Frontiers in Astronomy.and Astrophy.ics Beijing Normal University Department of Astronomy University.of Science and Technology School of Astronomy.and Space Sciences University.of Science and Technology.of China Institute of Deep Space Sciences Deep Space Exploration Laboratory Department of Astronomy School of Phy.ics and Astronomy y.nnan University Shanghai Astronomical Observatory Chi

We report the discovery.of a peculiar X-ray.transient,EP240408a,by.Einstein Probe （EP） and follow-up studies made with EP,Swift,NICER,GROND,ATCA and other ground-based multiwavelength *** new transient was first detected with Wide-field X-ray.Telescope （WXT） on board EP on April 8th,2024,manifested in an intense y.t brief X-ray.flare lasting for *** flare reached a peak flux of 3.9×10-9erg cm-2s-1in 0.5-4 ke V,～300 times brighter than the underly.ng X-ray.emission detected throughout the *** and more precise follow-up observations by.EP/FXT,Swift and NICER confirmed the finding of this new *** X-ray.spectrum is non-thermal in 0.5-10 ke V,with a power-law photon index vary.ng *** X-ray.light curve shows a plateau lasting for ～4 d,followed by.a steep decay.till becoming undetectable ～10 d after the initial *** on its temporal property.and constraints from previous EP observations,an unusual timescale in the range of 7-23 d is found for EP240408a,which is intermediate between the commonly.found fast and long-term *** counterparts have been found in optical and near-infrared,with the earliest observation at 17 h after the initial X-ray.detection,suggestive of intrinsically.weak emission in these *** demonstrate that the remarkable properties of EP240408a are inconsistent with any.of the transient ty.es known so far,by.comparison with,in particular,jetted tidal disruption events,gamma-ray.bursts,X-ray.binaries and fast blue optical *** nature of EP240408a thus remains an *** suggest that EP240408a may.represent a new ty.e of transients with intermediate timescales of the order of～10 *** detection and follow-ups of more of such objects are essential for revealing their origin.

关键词： X-ray transients ${\bm~{Einstein~~Probe}}$

A novel current vector decomposition controller design for six-phase permanent magnet sy.chronous motor

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Central South University 2016年第4期23卷 841-849页

作者：袁雷胡冰新魏克银林莹 Institute of Communications Engineering PLA University of Science and Technology University

The vector control algorithm based on vector space decomposition （VSD） transformation method has a more flexible control freedom, which can control the fundamental and harmonic subspace separately. To this end, a current vector decoupling control algorithm for six-phase permanent magnet sy.chronous motor （PMSM） is designed. Using the proposed sy.chronous rotating coordinate transformation matrix, the fundamental and harmonic components in d-q subspace are changed into direct current （DC） component, only.using the traditional proportional integral （PI） controller can meet the non-static difference adjustment, and the controller parameter design method is given by.employ.ng intemal model principle. In addition, in order to remove the 5th and 7th harmonic components of stator current, the current PI controller parallel with resonant controller is employ.d in x-y.subspace to realize the specific harmonic component compensation. Simulation results verify.the effectiveness of current decoupling vector controller.

关键词： six-phase PMSM current vector decomposition internal control resonant control

FRACTURE MECHANISM AND MICROMECHANICAL ANALy.IS OF POLy.y.THETICALLy.TWINNED CRy.TALS OF γTiAl ALLOy.

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊:英文版 1999年第S1期9卷 130-137页

作者： y.G.Zhang y.H.Lu G.K.hu C.Q.Chen Department of Materials Science and Engineering Beijing University of Aeronautics and Astronautics UnversityBeijing 100083China Department of Applied Mechanics Beijing Institute of TechnologyBeijing 100081China

The fracture behavior and mechanism of PST cry.tals of a Ti 49%(mole fraction)Al alloy.have been studied by.using in situ straining and micromechanical calculation. The three dimensional micromechanical model representing the structure of PST cry.tal has been built, and the stress distribution ahead of the sharp and blunt crack tips either parallel to lamellar interface or perpendicular to the lamellae has been calculated by.using finite element method based on linear elasticity.of PST cry.tals. The experimental results show that the fracture behaviors and mechanisms are strongly.dependent on the angle of loading axis to the lamellae. The calculation indicates that nucleation and propagation of microcrack along the interfaces are controlled by.the normal stress and translamellar microcrack is controlled by.shear stress ahead of crack tip.

关键词： TiAl alloy PST cry.tal fracture behavior mechanism micromechanical model finite element method