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有限维*子空间的强可分解性
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作者 赵君喜 《数学年刊(A辑)》 CSCD 北大核心 1999年第5期655-663,共9页
本文首先给出有限维*子空间的乘子代数及其子空间格的刻画,获得了CSL代数的另一个特征.其次讨论子空间的强可分解性,回答了关于*子空间强可分性的一个猜想.
关键词 *子空间 强可分解 有限维 代数 CSL代数
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Characteristic analysis of 1.06μm long-cavity diode lasers based on asymmetric waveguide structures
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作者 ZHAO Ren-Ze GAO Xin +3 位作者 FU Ding-Yang ZHANG Yue SU Peng BO Bao-Xue 《红外与毫米波学报》 SCIE EI CAS CSCD 北大核心 2024年第4期557-562,共6页
In long-cavity edge-emitting diode lasers,longitudinal spatial hole burning(LSHB),two-photon ab⁃sorption(TPA)and free carrier absorption(FCA)are among the key factors that affect the linear increase in out⁃put power a... In long-cavity edge-emitting diode lasers,longitudinal spatial hole burning(LSHB),two-photon ab⁃sorption(TPA)and free carrier absorption(FCA)are among the key factors that affect the linear increase in out⁃put power at high injection currents.In this paper,a simplified numerical analysis model is proposed for 1.06μm long-cavity diode lasers by combining TPA and FCA losses with one-dimensional(1D)rate equations.The ef⁃fects of LSHB,TPA and FCA on the output characteristics are systematically analyzed,and it is proposed that ad⁃justing the front facet reflectivity and the position of the quantum well(QW)in the waveguide layer can improve the front facet output power. 展开更多
关键词 diode lasers longitudinal spatial hole burning free carrier absorption two-photon absorption
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A Reduced-Order Modeling of Multi-Port RC Networks by Means of Graph Partitioning 被引量:1
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作者 杨华中 冒小建 +1 位作者 燕昭然 汪蕙 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2002年第10期1037-1040,共4页
A modified reduced-order method for RC networks which takes a division-and-conquest strategy is presented.The whole network is partitioned into a set of sub-networks at first,then each of them is reduced by Krylov sub... A modified reduced-order method for RC networks which takes a division-and-conquest strategy is presented.The whole network is partitioned into a set of sub-networks at first,then each of them is reduced by Krylov subspace techniques,and finally all the reduced sub-networks are incorporated together.With some accuracy,this method can reduce the number of both nodes and components of the circuit comparing to the traditional methods which usually only offer a reduced net with less nodes.This can markedly accelerate the sparse-matrix-based simulators whose performance is dominated by the entity of the matrix or the number of components of the circuits. 展开更多
关键词 INTERCONNECT reduced-order modeling graph partitioning Krylov subspace
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Orientation of Pigments in the Isolated PhotosystemⅡSub-core Reaction Center CP47/D1/D2/Cyt b-559 Complexes:A Linear Dichroism Study 被引量:3
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作者 侯建敏 Dominique DEJONGHE +2 位作者 单际修 李良璧 匡廷云 《Acta Botanica Sinica》 CSCD 2000年第12期1211-1214,共4页
Linear dichroism (LD) spectroscopy is an important technique in the study of the orientation and organization of pigments in the photosynthetic membrane complexes in vivo and in vitro . In this work, the orient... Linear dichroism (LD) spectroscopy is an important technique in the study of the orientation and organization of pigments in the photosynthetic membrane complexes in vivo and in vitro . In this work, the orientation of the pigments in the isolated photosystem Ⅱ (PSⅡ) sub_core reaction center complexes was analyzed and characterized by means of low temperature absorption and LD spectroscopy. The preparations containing different amounts of CP47 isolated from spinach (Spinacia oleracea L.) chloroplast were used in order to investigate the orientation of pigments in the PSⅡ sub_core CP47/D1/D2/Cyt b_559 (CP47/D1/D2) complexes. Chlorophyll a (Chl a) absorbing at 680 nm in CP47/D1/D2/Cyt b_559 complex showed an orientation of the Q y transition parallel to the membrane plane. It is proposed that there are two forms of β_carotene (β_Car) in CP47/D1/D2/Cyt b_559 complex, denoted as β_Car (Ⅰ) and β_Car (Ⅱ), with different orientations, β_Car (Ⅰ) at 470 and 505 nm is roughly parallel to the membrane plane, and β_Car (Ⅱ) at 460 and 490 nm seems to be perpendicular orientation. Upon the photoinhibitory experiment β_Car (Ⅱ) was found to be photosensitive and easily photodamaged. It also showed that the positive LD signal observed at 680 nm was quite complicated. This signal is tentatively attributed to P680 and some Chl a of antenna in CP47 protein based upon our measurements. 展开更多
关键词 orientation of pigments photosystemⅡ linear dichroism spectroscopy PHOTOINHIBITION
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Heterogeneity in Soil Seed Banks in a Mediterranean Coastal Sand Dune 被引量:9
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作者 于顺利 Marcelo STERNBERG +1 位作者 蒋高明 Pua KUTIEL 《Acta Botanica Sinica》 CSCD 2003年第5期536-543,共8页
Characteristics of total soil seed banks and permanent soil seed banks in three microhabitats in a Mediterranean coastal sand dune were investigated by using natural germination method combined with physically scannin... Characteristics of total soil seed banks and permanent soil seed banks in three microhabitats in a Mediterranean coastal sand dune were investigated by using natural germination method combined with physically scanning separation method. The composition and structure of soil seed banks were analyzed between the microhabitats by using functional group method. The distribution patterns of soil seed bank were also analyzed between the microhabitats. We also analyzed the relationship between seed size and seed persistence in soil. The results show greatly spatial heterogeneity existed in soil seed bank of the Mediterranean coastal sand dune, even in the same microhabitats seed distribution was uneven. Sometimes a great difference occurred between them. Microhabitats significantly affected the distribution patterns of total soil seed banks and seed banks of the functional groups. The open area generally had the greater densities of seeds, but the seed densities under shrub and in trail were lower than that in the open area. Legumes seeds accounted for 76.0% total persistent seed banks. Annual and perennial grasses produced transient seed banks as no seeds were retrieved from the sieved soils. Seed persistence of legumes, umbeliferaes, perennial forbs, compositaes, annual forbs, crucifer decreased gradually. They were 50.1%, 45.6%, 40.6%, 6.3%, 5.6% and 0.6% respectively in the soil. There was a positive relationship between seed size and seed persistence. Bigger seeds had higher persistence, and vice versa. 展开更多
关键词 MICROHABITATS soil seed banks persistent soil seed bank spatial heterogeneity
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IMPROVEMENT OF MATRIX REPRESENTATION METHOD IN NORMAL FORM THEORY 被引量:1
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作者 韩景龙 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2002年第2期166-171,共6页
In this paper, based on the invariant subspace theory and adjoint operator concept of linear operator, a new matrix representation method is proposed to calculate the normal forms of n order general nonlinear dyna... In this paper, based on the invariant subspace theory and adjoint operator concept of linear operator, a new matrix representation method is proposed to calculate the normal forms of n order general nonlinear dynamic systems. In the method, there is no need to determine the structure of the class of normal forms in advance. Because the subspace is not related to the dimensions of the system and the order of the normal forms directly, it is determined only by a given vector field. So the normal forms with high orders and dimensions can be calculated by the method without difficulties. In this paper, is used the method for selecting the minimal subspace and solving homological equations in the subspace, the examples show that the method is very effective. 展开更多
关键词 dynamic system normal forms NONLINEARITY linear space adjoint operator
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Optimal shape space and searching in the active shape model
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作者 何良华 邹采荣 +1 位作者 赵力 胡蝶 《Journal of Southeast University(English Edition)》 EI CAS 2005年第3期263-267,共5页
A novel idea,called the optimal shape subspace (OSS) is first proposed for optimizing active shape model (ASM) search.It is constructed from the principal shape subspace and the principal shape variance subspace.I... A novel idea,called the optimal shape subspace (OSS) is first proposed for optimizing active shape model (ASM) search.It is constructed from the principal shape subspace and the principal shape variance subspace.It allows the reconstructed shape to vary more than that reconstructed in the standard ASM shape space,hence it is more expressive in representing shapes in real life.Then a cost function is developed,based on a study on the search process.An optimal searching method using the feedback information provided by the evaluation cost is proposed to improve the performance of ASM alignment.Experimental results show that the proposed OSS can offer the maximum shape variation with reserving the principal information and a unique local optimal shape is acquired after optimal searching.The combination of OSS and optimal searching can improve the ASM performance greatly. 展开更多
关键词 active shape model shape subspace search subspace principal component analysis
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Seismic data analysis based on spatial subsets 被引量:2
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作者 蔡希玲 刘学伟 +2 位作者 李虹 钱宇明 吕英梅 《Applied Geophysics》 SCIE CSCD 2009年第4期384-392,395,共10页
There are some limitations when we apply conventional methods to analyze the massive amounts of seismic data acquired with high-density spatial sampling since processors usually obtain the properties of raw data from ... There are some limitations when we apply conventional methods to analyze the massive amounts of seismic data acquired with high-density spatial sampling since processors usually obtain the properties of raw data from common shot gathers or other datasets located at certain points or along lines. We propose a novel method in this paper to observe seismic data on time slices from spatial subsets. The composition of a spatial subset and the unique character of orthogonal or oblique subsets are described and pre-stack subsets are shown by 3D visualization. In seismic data processing, spatial subsets can be used for the following aspects: (1) to check the trace distribution uniformity and regularity; (2) to observe the main features of ground-roll and linear noise; (3) to find abnormal traces from slices of datasets; and (4) to QC the results of pre-stack noise attenuation. The field data application shows that seismic data analysis in spatial subsets is an effective method that may lead to a better discrimination among various wavefields and help us obtain more information. 展开更多
关键词 spatial subset 3D visualization high density sampling noise attenuation data analysis
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Mining maximal pattern-based subspace clusters in high dimensional space
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作者 卢炎生 胡蓉 +1 位作者 邹磊 周翀 《Journal of Southeast University(English Edition)》 EI CAS 2006年第4期490-495,共6页
The problem of pattern-based subspace clustering, a special type of subspace clustering that uses pattern similarity as a measure of similarity, is studied. Unlike most traditional clustering algorithms that group the... The problem of pattern-based subspace clustering, a special type of subspace clustering that uses pattern similarity as a measure of similarity, is studied. Unlike most traditional clustering algorithms that group the close values of objects in all the dimensions or a set of dimensions, clustering by pattern similarity shows an interesting pattern, where objects exhibit a coherent pattern of rise and fall in subspaces. A novel approach, named EMaPle to mine the maximal pattern-based subspace clusters, is designed. The EMaPle searches clusters only in the attribute enumeration spaces which are relatively few compared to the large number of row combinations in the typical datasets, and it exploits novel pruning techniques. EMaPle can find the clusters satisfying coherent constraints, size constraints and sign constraints neglected in MaPle. Both synthetic data sets and real data sets are used to evaluate EMaPle and demonstrate that it is more effective and scalable than MaPle. 展开更多
关键词 subspace clustering pattern similarity maximal pattern-based subspace clusters
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New subspace algorithm for blind channel estimation in OFDM systems
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作者 黄学军 余松煜 毕厚杰 《Journal of Southeast University(English Edition)》 EI CAS 2005年第2期132-135,共4页
In order to increase the transmission efficiency,a subspace-based algorithm for blind channel estimation using second-order statistics is proposed in orthogonal frequency division multiplexing (OFDM) systems.Because t... In order to increase the transmission efficiency,a subspace-based algorithm for blind channel estimation using second-order statistics is proposed in orthogonal frequency division multiplexing (OFDM) systems.Because the transmission equation of OFDM systems does not exactly have the desired structure to directly derive a subspace algorithm,the algorithm first divides the OFDM signals into three parts,then,by exploiting the redundancy introduced by the cyclic prefix (CP) in OFDM signals,a new equation with Toeplitz channel matrix is derived.Based on the equation,a new blind subspace algorithm is developed.Toeplitz structure eases the derivation of the subspace algorithm and practical computation.Moreover the algorithm does not change the existing OFDM system,is robust to channel order overdetermination,and the channel zero locations.The performances are demonstrated by simulation results. 展开更多
关键词 orthogonal frequency division multiplexing (OFDM) blind channel estimation subspace algorithm
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Multipliers of Hardy Spaces
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作者 郭继东 娄增建 《Chinese Quarterly Journal of Mathematics》 CSCD 2000年第4期69-73,共5页
本文刻划了Hardy空间H^p(1≤p≤∞)到Bloch空间的乘子,推广了前人的结果。
关键词 MULTIPLIER Hardy space BMOA Bloch space
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The Interpolation of Operators between Weighted Hardy Spaces and Weighted L^p Spaces 被引量:1
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作者 王月山 王伟民 《Chinese Quarterly Journal of Mathematics》 CSCD 2001年第2期54-58,共5页
The paper is given the interpolation of operators between weighted Hardy spaces and weighted L p spaces when w∈A 1 by Calderon Zygmund decomposition.
关键词 Calderon Zygmund decomposition interpolation of operator weighted Hardy space w-(p q s) atom
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Constrained least squares algorithm for channel vector estimation in 2-D RAKE receiver
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作者 王建明 赵春明 《Journal of Southeast University(English Edition)》 EI CAS 2003年第1期1-4,共4页
Based on the fact that the variation of tile direction of arrival (DOA) isslower than that of the channel fading, the steering vector of the desired signal is estimatedfirstly using a subspace decomposition method and... Based on the fact that the variation of tile direction of arrival (DOA) isslower than that of the channel fading, the steering vector of the desired signal is estimatedfirstly using a subspace decomposition method and then a constrained condition is configured.Traffic signals are further employed to estimate the channel vector based on the constrained leastsquares criterion. We use the iterative least squares with projection (ILSP) algorithm initializedby the pilot to get the estimation. The accuracy of channel estimation and symbol detection can beprogressively increased through the iteration procedure of the ILSP algorithm. Simulation resultsdemonstrate that the proposed algorithm improves the system performance effectively compared withthe conventional 2-D RAKE receiver. 展开更多
关键词 2-D RAKE receiver channel estimation subspace decomposition constrained least squares
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On n-K Width of Certain Function Classes Defined by Linear Differential Operators in L_2 Space
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作者 吴嘎日迪 包那 《Chinese Quarterly Journal of Mathematics》 CSCD 1999年第4期27-31, ,共5页
Let M(u) be an N function, A=D r+∑r-1k=0a k(x)D k a linear differential operator and W M(A) the Sobolev Orlicz class defined by M(u) and A. In this paper we give the asymptotic estimates... Let M(u) be an N function, A=D r+∑r-1k=0a k(x)D k a linear differential operator and W M(A) the Sobolev Orlicz class defined by M(u) and A. In this paper we give the asymptotic estimates of the n K width d n(W M(A),L 2[0,1]) . 展开更多
关键词 linear operator smooth function class WIDTH
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Iterative Solution for Systems of Binary Non-mixed Monotone Operator Equations 被引量:2
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作者 左秀会 《Chinese Quarterly Journal of Mathematics》 CSCD 2001年第3期80-83,共4页
With using the cone and partial ordering t heory and mixed monotone operator theory, the existence and uniqueness for solut ion of systems of non-monotone binary nonliear operator equations are discussed. And the it... With using the cone and partial ordering t heory and mixed monotone operator theory, the existence and uniqueness for solut ion of systems of non-monotone binary nonliear operator equations are discussed. And the iterative sequences which converge to solution of systems of operator e quations and the error estimates are also given. Some corresponding results for the mixed monotone operations and the unary operator equations are improved and generalized. 展开更多
关键词 binary operator mixed monotone operators syste ms of equations SOLUTIONS cone and partial ordering
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A spectrum measurement system for arc plasma with time and spatial indentification
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作者 李志勇 冯立 +1 位作者 杨军涛 范力予 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2015年第1期75-82,共8页
Spectrum analysis of the plasma has over the years been growing both in methods and instrument, which makes it become a widely used non-contact detection method, without disturbing the arc plasma itself. With noticeab... Spectrum analysis of the plasma has over the years been growing both in methods and instrument, which makes it become a widely used non-contact detection method, without disturbing the arc plasma itself. With noticeable developments in the industry application of the method, a need for careful analysis of the plasma with both time and space identification is desirable. Therefore, a spectral measurement system is developed in this paper for diagnosing arc plasma with time and space identification. With a new hollow probe scanning method, the instrument can be used to provide information like energy distribution of plasma, temperature within the arc plasma, which are of great significance with the requirement of space identification. Furthermore, the system can also be used to capture the instant state of the arc plasma with the synchronic triggering system, which uses high speed photo and electrical signal as the time criterion. The industry applications prove that the system works well for online detection of the arc plasma. 展开更多
关键词 SPECTRUM PLASMA time identification space identification
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Row-action SAGE algorithm for PET image reconstruction
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作者 周健 罗立民 朱宏擎 《Journal of Southeast University(English Edition)》 EI CAS 2004年第4期467-471,共5页
The one-block version of ordered subsets (OS) techniques was used to accelerate the convergent rate of the space-alternating generalized expectation-maximization (SAGE) algorithm. The new row-action SAGE (RA-SAGE) alg... The one-block version of ordered subsets (OS) techniques was used to accelerate the convergent rate of the space-alternating generalized expectation-maximization (SAGE) algorithm. The new row-action SAGE (RA-SAGE) algorithm processed projections in sequentially orthogonal order which reduced the dependency among the projections and speeds up the convergences. Additionally, the over-relaxation parameter in the direction defined by the RA-SAGE algorithm was also applied to obtain fast convergence to a globally maximum likelihood (ML) solution. In experiments, the RA-SAGE algorithm and the classical SAGE algorithm were compared in the application to positron emission tomography (PET) image reconstruction. Simulation results showed that RA-SAGE had better performance than SAGE in both convergence and image quality. 展开更多
关键词 Image quality Maximum likelihood estimation Positron emission tomography Signal to noise ratio
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Accelerating SAGE algorithm in PET image reconstruction by rescaled block-iterative method 被引量:1
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作者 朱宏擎 舒华忠 +1 位作者 周健 罗立民 《Journal of Southeast University(English Edition)》 EI CAS 2005年第2期207-210,共4页
A new method to accelerate the convergent rate of the space-alternatinggeneralized expectation-maximization (SAGE) algorithm is proposed. The new rescaled block-iterativeSAGE (RBI-SAGE) algorithm combines the RBI algo... A new method to accelerate the convergent rate of the space-alternatinggeneralized expectation-maximization (SAGE) algorithm is proposed. The new rescaled block-iterativeSAGE (RBI-SAGE) algorithm combines the RBI algorithm with the SAGE algorithm for PET imagereconstruction. In the new approach, the projection data is partitioned into disjoint blocks; eachiteration step involves only one of these blocks. SAGE updates the parameters sequentially in eachblock. In experiments, the RBI-SAGE algorithm and classical SAGE algorithm are compared in theapplication on positron emission tomography (PET) image reconstruction. Simulation results show thatRBI-SAGE has better performance than SAGE in both convergence and image quality. 展开更多
关键词 positron emission tomography space-alternating generalizedexpectation-maximization image reconstruction rescaled block-iterative maximum likelihood
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Multipliers on Weighted Hardy Spaces over Locally Compact Vilenkin Groups
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作者 朱月萍 《Chinese Quarterly Journal of Mathematics》 CSCD 2000年第4期18-26,共9页
This paper is devoted to study the atomic decomposition of the weighted Hardy space on Vilenkin groups and a weighted Hp multiplier theorem.
关键词 MULTIPLIERS Vilenkin group atom-decomposition
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Structural and Magnetic Property of Ion Irradiated TiO2 Single Crystals
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作者 丁斌峰 相风华 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2012年第1期19-24,I0003,共7页
Ferromagnetism is induced in pure TiO2 single crystals by oxygen ion irradiation. The ferro- magnetism is observed up to room temperature and is with weak temperature dependence. By combining X-ray diffraction, Ruther... Ferromagnetism is induced in pure TiO2 single crystals by oxygen ion irradiation. The ferro- magnetism is observed up to room temperature and is with weak temperature dependence. By combining X-ray diffraction, Rutherford backseattering/channelling, Raman scattering, and electron-spin resonance spectroscopy, supperconducting quantum interference device, displacement per atom, we measured tile lattice damage accumulation with increasing flu- ences. A defect complex, i.e., Ti3+ on the substitutional accoiflpanied by oxygen vacancies, has been identified in the irradiated Ti02. This kind of defect complex results in a local (TiO6-x) stretching Raman mode. We elucidate that Ti3+ with one unpaired 3d electron provide the local magnetic moments. 展开更多
关键词 Rutherford backscattering/channelling Displacement per atom Vacancy and interstitial
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