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Rare Metals 2016年第1期35卷 54-64页

作者： Li-Wei Zhang jun-Pin Lin Xiang-jun Xu Jian-Ping He Xian-Fei Ding Xiao-ou Jin State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Materials and Chemistry School Zhongyuan University of Technology National Center for Materials Service Safety University of Science and Technology Beijing School of Architecture and Engineering Heilongjiang University

Intermetallic Ti-xAl-8Nb（x = 41,43,45,47,49;at%） alloys were solidified unidirectionally upwards with a constant temperature gradient of G=3.8 K·mm^（-1）at wide range of growth rates of v=10-400 μm·s^（-1）using a Bridgman directional solidification（DS） *** parameters including the primary dendrite arm spacing（λ_1）,secondary dendrite arm spacing（λ_2）,dendrite tip radius（R） and mushy zone depth（d） were measured *** values of λ_1,λ_2,R and d decrease as the growth rate increases for a given composition（x）.The values of λ_1,λ_2,R and v increase with the increase in x value,while the value of d firstly increases and then decreases with the increase in x value for a given *** relationships between λ_1,λ_2 and R were analyzed by the linear *** average growth rate exponent of λ_1 is 0.29,which is in accordance with the previous experimental observations,and that of λ_2 is close to the previous experimental results,while those of R and d are lower than the results in other alloy *** addition,theoretical models for λ_1,λ_2 and R were compared with the experimental observations,and a comparison of the present experimental results with the theoretical models and previous experimental results was also made.

关键词： TiAl-Nb alloys Intermetallic Directionalsolidification Microstructural parameters Soluteconcentration

Post-modification engineering of cerium metal-organic frameworks for efficient visible light-driven water oxidation

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Rare Metals 2024年第11期43卷 5802-5812页

作者： Lin-Zhu Zhang Lu Chen Gui-Yang Yan Ruo-wen Liang Hong-Hui ou Fujian Provincial Key Laboratory of Featured Biochemical and Chemical Materials Fujian Province University Key Laboratory of Green Energy and Environment CatalysisNingde Normal UniversityNingde 352100China School of Chemical Engineering and Technology Xi'an Jiaotong UniversityXi'an 710049China

Metal-organic frameworks(MOFs)are highly desirable for promising photocatalytic water splitting,but their practical application is greatly limited due to their unstable chemical properties and insufficient visible light response as well as low charge-carries utilization,especially in photocatalytic O_(2)***,we present a post-modification engineering to modulate cerium metalorganic frameworks(Ce-MOFs)for realizing efficient photocatalytic water oxidation to liberate O_(2)by visible *** one-step partial oxidation strategy is adopted to modify pristine Ce-MOFs,yielding the new Ce-MOFs(MV-Ce-MOFs)with mixed valence of Ce^(3+)/Ce^(4+).Creating the Ce nodes of a mixed valence state can effectively extend the optical absorption to the visible region,expose more catalytically active sites and inhibit the recombination of photoinduced ***,the MV-Ce-MOFs exhibit high activity for photocatalytic O_(2)evolution under visible light,manifesting an impressive1.6%apparent quantum efficiency(AQY)under monochromatic irradiation of 405 *** regulation engineering of MOF metal node valence heralds a new paradigm for designing MOF-based photocatalysts.

关键词： Cerium metal-organic frameworks Partial oxidation Mixed valence Photocatalytic water oxidation Oxygen evolution

Effects of vegetation patch density on flow velocity characteristics in an open channel

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Journal of Hydrodynamics 2019年第5期31卷 1052-1059页

作者： wen-qi Li Dan Wang jun-li Jiao Ke-jun Yang State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan UniversityChengdu 610065China

The aquatic plants are often found in natural rivers,and they affect the channel flow structure *** study the effects of the vegetation density a(the frontal area per volume)on the flow velocity characteristics,rigid bamboo circular cylinders are chosen as the model emergent *** the experiments,the density of the vegetation takes various values while all other flow parameters are kept constant.A 3-D acoustic Doppler velocimeter(ADV)is used to measure the local flow velocities for different vegetation *** results show that the existence of the vegetation patch leads to an increase of the depth-averaged velocity on the right and left sides behind the vegetation patch,and it increases monotonically with the vegetation *** different vegetation densities,the lateral distribution of the stream-wise velocity behind the vegetation patch follows approximately an S-shaped profile when a≤60 m-1,and a logarithmic profile if a>60 *** vertical distribution of the stream-wise velocity along the channel varies with the vegetation density and also follows an S-shaped distribution in a certain range,with the locations and the ranges being affected by the vegetation density.

关键词： Vegetation density stream-wise velocity depth-averaged velocity lateral distribution longitudinal distribution open channel

Comparison of nonclassicality between photon-added and photon-subtracted squeezed vacuum states

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Chinese Physics B 2012年第2期21卷 301-308页

作者： Ma Shan-jun Luo wen-Wei College of Physics and Communication Electronics Jiangxi Normal UniversityNanchang 330022China

In this paper, we introduce photon-added and photon-subtracted squeezed vacuum state （PASV and PSSV） and obtain their normalized factors, which have the similar forms involved in Lengendre polynomials. Moreover, we give the compact expressions of Wigner function, which are related to single-variable Hermite polynomials. Especially, we compare their nonclassicality in terms of Mandel Q-factor and the negativity of Wigner function.

关键词： photon-added and photon-subtracted squeezed vacuum state nonclassicality Wigner function

Local Well-posedness for Linearized Degenerate MHD Boundary Layer Equations in Analytic Setting

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Acta Mathematica Sinica,English Series 2019年第8期35卷 1402-1418页

作者： Ya jun LI wen Dong WANG School of Mathematical Sciences Dalian University of Technology

In this note we derive MHD boundary layer equations according to viscosity and resistivity coefficients. Especially, when these viscosity and resistivity coefficients are of different orders, it leads to degenerate MH... 详细信息

关键词： MHD equations degenerate boundary layer equations local well-posedness analytic spaces

Spectral Characteristics of White Organic Light-emitting Diodes Based on Novel Phosphorescent Sensitizer

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Chinese Journal of Chemical Physics 2008年第6期21卷 510-514页

作者： Xiao-qing Tang jun-sheng Yu Lu Li wen wen Ya-dong Jiang State Key Laboratory of Electronic Thin Films and Integrated Devices School of Optoelectronic Information University of Electronic Science and Technology of China Chengdu 610054 China

White organic light-emitting diodes were fabricated by using a novel phosphorescence bis（1,2-diphenyl-1H-benzoimidazole）iridium（acetylacetonate）[（pbi）2Ir（acac）] as sensitizer and a fluorescent dye of 4- （dicyanomethylene）-2-t-butyl-6-（1,1,7,7-tetramethyljulolidyl-9-enyl）-4H-pyran （DCJTB） codoped into a carbazole polymer of poly（N-vinylcarbazole）（PVK）. Through characterizing the UV-Vis absorption spectra, the photoluminescence spectra of （pbi）2Ir（acac） and DCJTB, and the electroluminescence spectral properties of the WOLEDs, the energy transfer mechanisms of the codoped polymer system were deduced. The results demonstrate that the luminescent spectra with different intensity of （pbi）2Ir（acac） and DCJTB were co-existent in the EL spectra of the blended system, which is ascribed to an incomplete energy transfer process in the EL process. The efficient Forster and Dexter energy transfer between the host and the guests enabled a strong yellow emission from （pbi）2Ir（acac） and DCJTB, where （pbi）2Ir（acac） plays an important role as a phosphorescent sensitizer for DCJTB. With the blue emitting-layer of N,N＇-diphenyl-N,N＇-bis（1- naphthyl）（1,1＇-biphenyl）-4,4＇-diamine, the codoped system device achieved white emission. The codoped system showed that its Commissions Internationale de 1＇Eclairage coordinates were more independent of the variation of bias voltage than those of phosphorescent doped PVK systems.

关键词： White organic light-emitting diode Phosphorescent sensitizer Spectrum analysis

Constraints on the skewness coefficient of symmetric nuclear matter within the nonlinear relativistic mean field model

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Nuclear Science and Techniques 2017年第12期28卷 279-287页

作者： Bao-jun Cai Lie-wen Chen School of Physics and Astronomy and Shanghai Key Laboratory for Particle Physics and Cosmology Shanghai Jiao Tong UniversityShanghai 200240China

Within the nonlinear relativistic mean field(NLRMF) model, we show that both the pressure of symmetric nuclear matter at supra-saturation densities and the maximum mass of neutron stars are sensitive to the skewness coefficient, J_0, of symmetric nuclear matter. Using experimental constraints on the pressure of symmetric nuclear matter at supra-saturation densities from flow data in heavy-ion collisions and the astrophysical observation of a large mass neutron star PSR J0348+0432, with the former favoring a smaller J_0 while the latter favors a larger J_0, we extract a constraint of -494 MeV≤J_0≤-10 MeV based on the NL-RMF model. This constraint is compared with the results obtained in other analyses.

关键词： Equation of state of nuclear matter Heavy-ion collisions Neutron stars

On an Entropy of Zk＋-Actions

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Acta Mathematica Sinica,English Series 2014年第3期30卷 467-480页

作者： Yu jun ZHU wen Da ZHANG College of Mathematics and Information Science and Hebei Key Laboratory of Computational Mathematics and ApplicationsHebei Normal University College of Mathematics and Information Science Hebei Normal University

In this paper,a definition of entropy for Z＋k（k≥2）-actions due to Friedland is *** the traditional definition,it may take a nonzero value for actions whose generators have finite（even zero） entropy as single *** basic properties are investigated and its value for the Z＋k-actions on circles generated by expanding endomorphisms is ***,an upper bound of this entropy for the Z＋k-actions on tori generated by expanding endomorphisms is obtained via the preimage entropies,which are entropy-like invariants depending on the ＂inverse orbits＂ structure of the system.

关键词： Entropy preimage entropy Zk+-action

Grasp evaluation and contact points planning for polyhedral objects using a ray-shooting algorithm

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Journal of Zhejiang University-Science C(Computers and Electronics) 2012年第3期13卷 218-231页

作者： Shuang-quan wen Tie-jun WU Department of Control Science and Engineering Zhejiang UniversityHangzhou 310027China

Grasp evaluation and planning are two fundamental issues in robotic grasping and dexterous manipulation. Most traditional methods for grasp quality evaluation suffer from non-uniformity of the wrench space and a dependence on the scale and choice of the reference frame. To overcome these weaknesses, we present a grasp evaluation method based on disturbance force rejection under the assumption that the normal component of each individual contact force is less than one. The evaluation criterion is solved using an enhanced ray-shooting algorithm in which the geometry of the grasp wrench space is read by the support mapping. This evaluation procedure is very fast due to the efficiency of the ray-shooting algorithm without linearization of the friction cones. Based on a necessary condition for grasp quality improvement, a heuristic searching algorithm for polyhedral object regrasp is also proposed. It starts from an initial force-closure unit grasp configuration and iteratively improves the grasp quality to find the locally optimum contact points. The efficiency and effectiveness of the proposed algorithms are illustrated by a number of numerical examples.

关键词： Force closure Grasp quality evaluation Multifingered grasp Grasping planning Ray-shooting

Higher order asymptotic behaviour of partial maxima of random sample from generalized Maxwell distribution under power normalization

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Applied Mathematics(A Journal of Chinese Universities) 2018年第2期33卷 177-187页

作者： HUANG Jian-wen WANG Jian-jun School of Mathematics and Statistics Southwest University Research Center for Artificial Intelligence & Education Big Data Southwest University

In this article, the higher order asymptotic expansions of cumulative distribution function and probability density function of extremes for generalized Maxwell distribution are established under nonlinear normalization. As corollaries, the convergence rates of the distribu- tion and density of maximum are obtained under nonlinear normalization.

关键词： higher order expansion extreme generalized Maxwell distribution nonlinear normalization