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Red-emitting CaWO4:Eu^(3+),Tm^(3+)phosphor for solid-state lighting:luminescent properties and morphology evolution

Journal of Rare Earths 2022年第2期40卷 226-233,I0002页

作者： l.x.lovisa I.M.P.da Silva A.A.G.Santiago M.Siu li E.longo C.A.Paskocimas M.R.D.Bomio F.V.Motta Institute of Physics and Chemistry.Federal University of Itajubd(UNIFEI) ItajubdMG37500-903Brazil lSQM-laboratory of Chemical Synthesis of Materials-Department of Materials Engineering Federal University of Rio Grande Do NorteP.O.Box 152459078-900Natal RNBrazil IFSC USPAv.Trabalhador Sao Carlense400CEP 13566-590Sao CarlosSPBrazil CDMF-lIEC UFSCarP.O.Box 67613565-905Sao Carlos.SPBrazil

CaWO_(4):xEu^(3+),yTm^(3+)crystals were obtained by facile synthesis at low temperature by the microwaveassisted hydrothermal method(MAH).The phase formation,morphology,luminescent properties and ene rgy transfer were *** x-ray diffraction(xRD)re sults show the formation of a scheelitelike tetragonal structure without the presence of secondary *** growth mechanism of hierarchical micro structures based on self-assembly and Ostwald-ripening processes was evaluated,obtaining different types of *** luminescence spectra of CaWO_(4):Eu^(3+),Tm^(3+)at 325 nm excitation show the predominance of red emission at the 5 D0→7 F2(Eu^(3+))transition at 624 *** feature signals dominant behavior of the electric dipole *** presence of Tm^(3+)is notably evident in the absorption spectra by the related excitation transitions:3 H6→1 G4,3 H6→3 F3 and 3 H6→3 *** parameters are discussed to characterize CaWO_(4):Eu^(3+),Tm^(3+)*** study of the emission spectrum as a function of the concentration of Eu^(3+)(x mol%)and Tm^(3+)(y mol%)indicates that the CaWO_(4):Eu^(3+),Tm^(3+)phosphors show stronger red emission intensity and exhibit the CIE value of x=0.63 and y=*** photoluminescence results show 97%high color purity for CaWO_(4):4 mol%Eu^(3+),a high CRI(92%)and a low CCT of 1085 *** results demonstrate that the CaWO_(4):Eu^(3+),Tm^(3+)red phosphors are promising as color converters for application in white light-emitting diodes and display devices.

关键词： CaWO_(4):Eu^(3+),Tm^(3+)microwave-assisted hydrothermal method Photoluminescence Red phosphor Rare earths

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STRAIN RATE SENSITIVITY OF UlTRAFINE-GRAINED Cu WITH NANOSIZED TWINS

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Acta Metallurgica Sinica(English letters) 2006年第5期19卷 313-318页

作者： l.x. liu x.H. Chen l. lu Shenyang National laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

An ultrafine-grained Cu sample with a high density of growth twins was synthesized by means of pulsed electrodeposition technique. The strain rate sensitivity of the Cu sample was measured by strain rate cycling tests under tension. The effects of grain size as well as twin density on the strength and strain rate sensitivity were discussed.

关键词： copper nanosized twin strain rate sensitivity deformation mechanism

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Fluid-structure interaction in Z-shaped pipe with different supports

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Acta Mechanica Sinica 2020年第2期36卷 513-523页

作者： Q.Guo J.x.Zhou x.l.Guan College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing 210098China Highway Science and Technology Research Institute Xinjiang Production and Construction Corpsürümqi 830002China

Fluid-structure interaction(FSI)has a strong relation with layout of fluid delivery *** is liable to cause local ***,FSI analysis is necessary in many cases,especially for flexible pipe *** modeling consists of eight governing equations and then completely solved via the finite volume method(FVM).Friction,Poisson and joint couplings were discussed in detail to reveal the influence of a Z-shaped pipe with different supports and elbows on *** the feasibility of solving FSI by FVM was verified,the different effects of free,fixed and elastic supports on FSI in the commonly used and simplified Z-shaped pipe were further *** indicated that different support stiffness lead to various FSI *** coupling occurs at the elbow and less support is considered,then the pipe has a relatively large amplitude and complex pressure fluctuation.

关键词： Fluid-structure interaction Finite volume method Z-shaped pipe Support stiffness

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Beginning from the end:the presynaptic terminal as a pathomechanism hub in frontotemporal dementia and amyotrophic lateral sclerosis

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Neural Regeneration Research 2025年第11期20卷 3217-3218页

作者： laura Huggon Emma l.Clayton UK Dementia Research Institute at King’s College london LondonUK Department of Basic and Clinical Neuroscience Institute of Psychiatry Psychology&NeuroscienceKing’s College LondonLondonUK

Frontotemporal dementia and amyotrophic lateral sclerosis:Frontotemporal dementia(F T D)and amyo t rophic lateral sclerosis(AlS)are neurodegenerative diseases with significant overlapping *** these neurodegenerative diseases affect different neuronal populations(with FTD affecting neurons of the frontal and temporal lobes,and AlS affecting upper and lower motor neurons),these two diseases are complexly *** and AlS exist on a disease spectrum,with shared genetic causes,clinical presentations,and pathologies.

关键词： diseases amyotrophic sclerosis

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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

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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

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Elastic-plastic behavior of a semicircular frame being pressed against a rigid plane

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Acta Mechanica Sinica 2008年第4期24卷 419-432页

作者： x.W.Zhang J.l.Yang T.x.Yu Institute of Solid Mechanics Beihang University Beijing 100083 China Department of Mechanical Engineering Hong Kong University of Science and Technology Kowloon Hong Kong China

As a simplified structural model, a semicircular frame is used to study the crashworthiness behavior of an aircraft fuselage. The quasi-static large elastic-plastic deformation of a semicircular frame in the process of its being pressed against a rigid ground is analyzed. First, based on the linear elastic assumption, the quasi-static large deformation contact process of the frame can be divided into three phases, i.e., point contact, line contact and post-buckling. By means of a shooting method, the relations between the displacement and contact force as well as the distribution of bending moment in the three phases are obtained. Then, by assuming an elastic, perfectly-plastic moment-curvature relationship for the semi-circular frame, the contact process is analyzed in detail to reveal the plastic collapse mechanism, the traveling of plastic hinge and the force-displacement relationship. In order to verify the analysis, a preliminary experiment was conducted, in which two types of half rings with clamped ends were pressed by a rigid plate. In addition, a numerical simulation is also conducted by employing ABAQUS to analyze both rectangular cross-sectional beam and I-beam. Finally, the theoretical predictions are compared with the experimental results and numerical solutions, showing that the elastic-plastic analysis can predict the contact process very well.

关键词： Elastic-plastic·large deformation ·Semicircular frame Contact ·Traveling hinge

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

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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

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A review——Pitting corrosion initiation investigated by TEM

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Journal of Materials Science & Technology 2019年第7期35卷 1455-1465页

作者： B.Zhang x.l.Ma Shenyang National laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences

Passive metals have superior resistance to general corrosion but are susceptible to pitting attack in certain aggressive media, leading to material failure with pronounced adverse economic and safety consequences. Over the past decades, the mechanism of pitting corrosion has attracted corrosion community striving to study. However, the mechanism at the pitting initiation stage is still controversy, due to the difficulty encountered in obtaining precise experimental information with enough spatial *** the accurate sites where initial dissolution occurs as well as the propagation of the dissolution by means of multi-scale characterization is key to deciphering the link between microstructure and corrosion at the atomic scale and clarifying the pitting initiation mechanism. Here, we review our recent progresses in this issue by summarizing the results in three representative materials of 316F, and Super 304H stainless steel as well as 2024-Al alloy, using in situ ex-environmental TEM technique.

关键词： Pitting initiation Dissolution TEM Inclusion Second phase

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Model on l-to H-Mode Transition Driven with lower-Hybrid Wave

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Chinese Physics letters 1994年第11期11卷 677-680页

作者： QIU xiaoming(x.M.Qiu) BAI lin(l.Bai) Southwestern Institute of Physics P.O.Box 432Chengdu 610041

In this letter,a model for active suppressing tokamak edge turbulence and hence inducing the l-mode to H-mode transition with lower-hybrid wave(lHW)is *** model includes the two contents:(a)The poloidal sheared flow of plasma is generated by the ponderomotive potential and induced magnetization acting on a tokamak plasma resulting from the oscillating electric field of the injected lHW.(b)During the time the lHW is injected into tokamak edge,the edge turbulence and the lHW-generated plasma poloidal flow compete with each other;if the shear of plasma poloidal flow is large enough to suppress the edge turbulence,the confinement will be remarkably improved and hence the system will enter the H operating *** model leads us to find that the threshold lHW power required for edge-turbulence suppression is proportional to A(ω)≡(ω/ωlH)^(2)|(ω/ωlH)^(2)-1|,which enables us to explain the experiment in the JT-60 tokamak with lower-hybrid current drive.

关键词： turbulence hence flow

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