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diagonal invariant ideals of Toeplitz algebras on discrete groups

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Science China Mathematics 2002年第4期45卷 462-469页

作者：许庆祥 Department of Mathematics Shanghai Normal University Shanghai China

diagonal invariant ideals of Toeplitz algebras defined on discrete groups are introduced and studied. In terms of isometric representations of Toeplitz algebras associated with quasi-ordered groups, a character of a discrete group to be amenable is clarified. It is proved that when G is Abelian, a closed two-sided non-trivial ideal of the Toeplitz algebra defined on a discrete Abelian ordered group is diagonal invariant if and only if it is invariant in the sense of Adji and Murphy, thus a new proof of their result is given.

关键词： discrete ordered group, Toeplitz algebra, diagonal invariant ideal.

Adaptive diagonal loaded minimum variance beamforming applied to medical ultrasound imaging

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Journal of Central South University 2015年第5期22卷 1826-1832页

作者：刘昊霖张志宏刘东权 College of Computer Science Sichuan University Department of Computer Science and Technology Changsha University Saset Healthcare Inc

In order to enhance the robustness and contrast in the minimum variance(MV) beamformer, adaptive diagonal loading method was proposed. The conventional diagonal loading technique has already been used in the MV beamformer, but has the drawback that its level is specified by predefined parameter and without consideration of input-data. To alleviate this problem, the level of diagonal loading was computed appropriately and automatically from the given data by shrinkage method in the proposed adaptive diagonal loaded beamformer. The performance of the proposed beamformer was tested on the simulated point target and cyst phantom was obtained using Field II. In the point target simulation, it is shown that the proposed method has higher lateral resolution than the conventional delay-and-sum beamformer and could be more robust in estimating the amplitude peak than the MV beamformer when acoustic velocity error exists. In the cyst phantom simulation, the proposed beamformer has shown that it achieves an improvement in contrast ratio and without distorting the edges of cyst.

关键词： medical ultrasound imaging minimum variance beamforming diagonal loading delay-and-sum beamforming contrast robustness

Effects of Off-diagonal Electron-Electron Interactions on Exciton Energies in C_(60)

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Chinese Physics Letters 1996年第11期13卷 863-866页

作者： RAO Xue-song ZHAO Hua FU Rou-li SUN Xin KNASU t.4.lee laboratory and department of physics fudan universityshanghai 200433 and national laboratory of infrared physicschinese academy of sciencesshanghai200083 national laboratory for high energy physics tsukubaibaraki 305japan

Since the neighboringπorbits in C_(60) are well overlapped,the off-diagonal part of electron interaction plays an important role.In this paper,the effects of the off-diagonal electron interactions on the exciton energies in C_(60) are studied by using the single configuration interaction approach.It is found that the binding energies of the low-lying singlet and triplet excitons depend sensitively upon the off-diagonal interactions which compete against the diagonal interactions and suppress the binding of the excitons.The implication of these features is discussed.

关键词： diagonal Electron interaction

On relations between R_aR_b transformation and canonical diagonal form of λ-matrix

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维普期刊数据库

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Science China(Technological Sciences) 1997年第3期40卷 258-268页

作者：陶仁骥冯培荣 Institute of Software Chinese Academy of Sciences Beijing 100080 China

RaRb transformation over λ-matrix is defined and explored. Relations between Ra Rb transforma tion over λ-matrix and canonical diagonal form of λ-matrix are investigated and some results are

关键词： λ-matrix canonical diagonal form Ra Rb transformation finite automata.

Hybrid reconstruction algorithm for computed tomography based on diagonal total variation

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Nuclear Science and Techniques 2018年第3期29卷 172-180页

作者： Lu-Zhen Deng Peng He Shang-Hai Jiang Mian-Yi Chen Biao Wei Peng Feng Key Laboratory of Optoelectronic Technology and Systems Ministry of Education Chongqing University Department of Radiation Physics The University of Texas MD Anderson Cancer Center ICT NDT Engineering Research Center Ministry of Education Chongqing University Collaborative Innovation Center for Brain Science Chongqing University

Inspired by total variation(TV), this paper represents a new iterative algorithm based on diagonal total variation(DTV) to address the computed tomography image reconstruction problem. To improve the quality of a reconstructed image, we used DTV to sparsely represent images when iterative convergence of the reconstructed algorithm with TV-constraint had no effect during the reconstruction process. To investigate our proposed algorithm, the numerical and experimental studies were performed, and rootmean-square error(RMSE) and structure similarity(SSIM)were used to evaluate the reconstructed image quality. The results demonstrated that the proposed method could effectively reduce noise, suppress artifacts, and reconstruct highquality image from incomplete projection data.

关键词： Computed tomography (CT) Sparse-view reconstruction diagonal total variation (DTV) Compressive sensing (CS)

NONNULL　DISTRIBUTION　OF　THE　LIKELIHOOD　RATIO　CRITERION　FOR　TESTING　THE　EQUALITY　OF　diagonal　BLOCKS　WITH　BLOCKWISE　INDEPENDENCE

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Acta Mathematica Scientia 1994年第2期14卷 195-203页

作者： A. K. Gupta C. C. Chao(Bowling Green State University Bowling Green, OH 43403-0221 C. C. ChaoJacksonville State Univesity Jacksonville, AL 36265) Bowling Green State University Bowling Green OH 43403–0221 Jacksonville State Univesity Jacksonville AL 36265

In this paper, the nonnull moments and the distributions of the likelihood ratio criterion for testing the equality of diagonal blocks with blockwise independence under certain alternatives have derived.

关键词： RATIO BLOCKWISE CRITERION diagonal DISTRIBUTION EQUALITY FOR INDEPENDENCE LIKELIHOOD NONNULL

Products of diagonal Operators~*

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Chinese Science Bulletin 1993年第4期38卷 265-268页

作者：吴培元侯晋川高明杵张秀玲 Department of Applied Mathematics Taiwan Chiao Tung University Hsinchu Department of Mathematics Shanxi Teachers University Linfen 041004 PRC

Let X be a separable complex Hilbert space, B(X)the set of all (bounded linear)operators acting on X. For T∈B(X), the question whether T can be factorized into the product of some good operators has been discussed by many authors (e. g. Ref. [1]—[6]). In [1], Wu obtained some sufficient and necessary conditions for an operator to be a prod-

关键词： Hilbert spaces diagonal operators normal operators.

Congestion　Control　for　ATM　Networks　Based　on　diagonal　Recurent　Neural　Networks

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通信学报 1997年第3期18卷 92-97页

作者： Huang Yunxian Yan Wei (Air Force Institute of Meteorology,Nanjing 211101) Air Force Institute of Meteorology 江苏南京 211101 Air Force Institute of Meteorology 江苏南京

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关键词： diagonal recurrent neural networks congestion control ATM networks

Moiré-driven electromagnetic responses and magic angles in a sandwiched hyperbolic metasurface

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Photonics Research 2022年第9期10卷 2056-2065页

作者： YI LIU CHUNMEI OUYANG QUAN XU XIAOQIANG SU QUANLONG YANG JIAJUN MA YANFENG LI ZHEN TIAN JIANQIANG GU LIYUAN LIU JIAGUANG HAN YUNLONG SHI WEILI ZHANG Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering Key Laboratory of Optoelectronic Information Technology(Ministry of Education of China)Tianjin UniversityTianjin 300072China Institute of Solid State Physics College of Physics and Electronic ScienceShanxi Province Key Laboratory of Microstructure Electromagnetic Functional MaterialsShanxi Datong UniversityDatong 037009China Nonlinear Physics Centre Australian National UniversityCanberraACT 2601Australia School of Electrical and Computer Engineering Oklahoma State UniversityStillwaterOklahoma 74078USA

Recent moiréconfigurations provide a new platform for tunable and sensitive photonic responses,as their enhanced light–matter interactions originate from the relative displacement or rotation angle in a stacking bilayer or multilayer periodic array.However,previous findings are mostly focused on atomically thin condensed matter,with limitations on the fabrication of multilayer structures and the control of rotation angles.Structured microwave moiréconfigurations are still difficult to realize.Here,we design a novel moiréstructure,which presents unprecedented capability in the manipulation of light–matter interactions.Based on the effective medium theory and S-parameter retrieval process,the rotation matrix is introduced into the dispersion relation to analyze the underlying physical mechanism,where the permittivity tensor transforms from a diagonal matrix to a fully populated one,whereas the permeability tensor evolves from a unit matrix to a diagonal one and finally becomes fully filled,so that the electromagnetic responses change drastically as a result of stacking and rotation.Besides,the experiment and simulation results reveal hybridization of eigenmodes,drastic manipulation of surface states,and magic angle properties by controlling the mutual rotation angles between two isolated layers.Here,not only a more precisely controllable bilayer hyperbolic metasurface is introduced to moiréphysics,the findings also open up a new avenue to realize flat bands at arbitrary frequencies,which shows great potential in active engineering of surface waves and designing multifunctional plasmonic devices.

关键词： rotation hyperbolic diagonal