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Shaking table comparative test and associated study of a stepped wall-frame structure

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Earthquake Engineering and Engineering Vibration 2014年第3期13卷 471-485页

作者： Xu Weixiao Sun Jingjiang Yang Weisong du ke key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering Mechanics China Earthquake Administration

A new structural system called a stepped wall-frame structure is proposed in this study to solve the bottom yielding problem of RC frames, which widely occurred during previous earthquakes such as thc Wcnchuan and Yushu earthquakes in China. A 1/5 scale ordinary RC frame model and a stepped wall-frame model were subjected to shake table motions together to study the seismic behavior of the new structural system. This paper presents the dynamic characteristics, the seismic responses and the failure and collapse mechanism of the two models under low, moderate and high intensity shaking. The test results and further analysis demonstrate that the seismic performance of stepped wall-frame structures is superior to ordinary RC frames in terms of the well-controlled deformation pattern and more uniformly distributed damage. The stepped wall can effectively suppress the bottom yielding mechanism, and is simple, economical and practical tbr engineering practice.

关键词： stepped wall-flame strt, cture damage mechanism control shake table test drift ratio collapse mechanism

A Note on the Left Essential Spectra of Operator Matrices

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Acta Mathematica Sinica,English Series 2007年第12期23卷 2235-2240页

作者： Yuan LI Xiu Hong SUN Hong ke du College of Mathematics and Information Science Shaanxi Normal University Xi'an 710062 P. R. China Department of Basic Courses Xi'an University of Science and Technology Xi'an 710054 P. R. China College of Mathematics and Information Science Shaanxi Normal University Xi'an 710062 P. R China

When A ∈ B（H） and B ∈ B（K） are given, we denote by Me the operator matrix acting on the infinite dimensional separable Hilbert space H ＋ K of the form Me = （ A C O B）. In this paper, a necessary and sufficient condition for Me to be left Fredholm for some C ∈ F（K, H）（C ∈ Inv（K, H）） is given, where F（K,H） and Inv（K, H） denote respectively, the set of Fredholm operators and the set of invertible operators of B（K, H）. In addition, we give a necessary and sufficient condition for Me to be left Fredholm for all C ∈ Inv（K, H）.

关键词： left essential spectrum 2×2 operator matrix perturbations of spectra

On the Index of Fredholm Pairs of Idempotents

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Acta Mathematica Sinica,English Series 2009年第4期25卷 679-686页

作者： Yue Qing WANG Hong ke du Yan Ni DOU Department of Mathematics and Physics Chongqing University of Science and Technology Chongqing 400042 P. R. China College of Mathematics and Information Science Shaanxi Normal University Xi'an 710062 P. R. China

Using the technique of block-operators, in this note, we prove that if P and Q are idempotents and （P - Q）^2n＋1 is in the trace class, then （P - Q）^2m＋1 is also in the trace class and tr（P - Q）^2m＋1 = dim（k（P） ∩ k（Q）^⊥） -dim（k（P）^⊥ N k（Q））, for all m ≥ n. Moreover, we prove that dim（k（P）∩ k（Q）^⊥） = dim（k（P）^⊥ ∩k（Q）） if and only if there exists a unitary U such that UP = QU and PU = UQ, where k（T） denotes the range of T. keywords Fredholm, orthogonal projection, positive operator

关键词： Fredholm orthogonal projection positive operator

Γ-inverses of Bounded Linear Operators

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Acta Mathematica Sinica,English Series 2014年第4期30卷 675-680页

作者： Xiao Ming XU Hong ke du Xiao Chun FANG School of Science Shanghai Institute of Technology College of Mathematics and Information Science Shaanxi Normal University Department of Mathematics Tongji University

Let B（Н） be the algebra of all the bounded linear operators on a Hilbert space Н. For A, P and Q in B（Н）, if there exists an operator X ∈ B（Н） such that APXQA = A, XQAPX = X, （QAPX）^＊ = QAPX and （XQAP）^＊ = XQAP, then X is said to be the F-inverse of A associated with P and Q, and denoted by A^＋P,Q. In this note, we present some necessary and sufficient conditions for which A^＋P,Q exists, and give an explicit representation of A^＋PQ （if A^＋P,Q exists）.

关键词： Generalized inverse F-inverse Moore-Penrose inverse

Preparation of spherical spinel LiCr_(0.04)Mn_(1.96)O_4 cathode materials based on the slurry spray drying method

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Rare Metals 2009年第6期28卷 618-623页

作者： JIANG Qinglai HU Guorong PENG Zhongdong du ke CAO Yanbing TANG Daichun School of Metallurgical Science and Engineering Central South University Changsha 410083 China

Regular spherical chromium doped spinel lithium manganese oxides （LiCr0.04Mn1.96O4） with an average particle size of about 20μm were prepared by the slurry spray drying process. The materials were compared with non-spherical LiCr0.04Mnl.96O4 materials prepared by the common drying process, and all materials were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, laser particle analyzer and Brunaner-Emmett-Teller （BET） specific surface area test. Electrochemical performances of these cathode materials were studied by cyclic voltammetry （CV）, electrochemical impedance spectroscopy （EIS） and Li/LiCr0.04Mn1.9604 battery test. The results show that the spherical active material is single spinel structure, compact, and with narrow particle size distribution and low BET specific surface area. Compared with the non-spherical material, the spherical material prepared by the spray drying process shows a lower electrochemical impedance, a fewer electrochemical polarization and a better charge/discharge rate capability and capacity retention at elevated temperatures.

关键词： lithium-ion battery spinel LiMn2O4 spray drying chromium doping

Layer-by-layer assembly of chitosan and carbon nanotube on cotton fabric for strain and temperature sensing

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Journal of Materials Science & Technology 2024年第6期173卷 114-120页

作者： Ye-Xin Zhang Yi-Dong Li An-ke du Yuanpeng Wu Jian-Bing Zeng Chongqing key Laboratory of Soft-Matter Material Chemistry and Function Manufacturing School of Chemistry and Chemical EngineeringSouthwest UniversityChongqing 400715China Chongqing Academy of Science and Technology Chongqing 401123China School of New Energy and Materials State Key Laboratory of Oil and Gas Reservoir Geology and ExploitationSouthwest Petroleum UniversityChengdu 610500China

Layer-by-layer(LBL)assembly shows great potential in fabrication of flexible conductive cotton fabrics(FCCF)with carbon nanotubes(CNT)as conductive components but is limited because complicated chemical modification of CNT is usually ***,we reported a facile and eco-friendly LBL approach to fabricating FCCF by dipping in chitosan(CS)aqueous solution and poly(sodium 4-styrenesulfonate)(PSS)wrapped CNT aqueous dispersion *** FCCF with electrical conductivity higher than 30 S/m was achieved when 4 layers of CNT were coated on the cotton fabric(CF).The obtained FCCF possessed outstanding mechanical stability with electrical resistivity almost unchanged after exposure to 500 times mechanical abrasion and 500 circles of tape *** FCCF showed excellent strain sensing performance with high sensitivity(with a gauge factor up to 35.1)and a fast response time(70 ms).It can be used as a strain sensor to accurately detect various human deformations such as finger bending and joint *** FCCF could be used as a temperature sensor in that it exhibited stable and reproducible negative temperature sensing behavior in the temperature range of 30-100℃.

关键词： Flexible conductive cotton fabric Layer-by-layer Temperature sensing Strain sensing

PropertyΠ_σand tensor products of operator algebras

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Science China Mathematics 2007年第12期50卷 1680-1686页

作者： Jian-hua ZHANG Hong-ke du Hui-xin CAO College of Mathematics and Information Science Shaanxi Normal University Xi'an 710062 China College of Mathematics and Information Science Shaanxi Normal University Xi'an 710062 China College of Mathematics and Information Science Shaanxi Normal University Xi'an 710062 China

In this paper, we introduce Property ∏σ of operator algebras and prove that nest subalgebras and the finite-width CSL subalgebras of arbitrary von Neumann algebras have Property ∏σ.Finally, we show that the tensor product formula alg ML1-(×)algNL2 = algM-(×)N(L1 (×) L2) holds for any two finite-width CSLs L1 and L2 in arbitrary von Neumann algebras M and N, respectively.

关键词： Property ∏σ, tensor product, nest subalgebra, CSL subalgebra

The Representations of Generalized Inverses of Lower Triangular Operators

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Acta Mathematica Sinica,English Series 2009年第12期25卷 2107-2118页

作者： Chun Fang SHAO Hong ke du Shu Feng JI Jun Lian XU College of Mathematics and Information Science Shaanxi Normal University Xi'an 710062 P. R. China Department of Mathematics Ankang University Ankang 725000 P. R. China

In this note, the explicit representations of Moore-Penrose inverses of lower triangular operator matrices are established. As an application, the explicit representations of Bott-duffin inverses of bounded linear ope... 详细信息

关键词： Moore-Penrose inverse lower triangular operator matrix Bott-duffin inverse

Young's Inequality for Positive Operators

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Journal of Mathematical Research and Exposition 2011年第5期31卷 915-922页

作者： Li FANG Hong ke du Department of Mathematics Northwest University Shaanxi 710127 P. R. China College of Mathematics and Information Science Shaanxi Normal University Shaanxi 710062 P. R. China

The classical Young’s inequality and its refinements are applied to positive operators on a Hilbert space at first. Based on the classical Poisson integral formula of relevant operators, some new inequalities on unitarily invariant norm of A1-p XB1-q - A1-q Y B1-p are obtained with effective calculation, where A, B, X, Y ∈ B（H） with A, B 0 and 1 p, q ∞ with the conjugate exponent q = p/（p - 1）.

关键词： Young’s inequality positive operator.