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A distribution space for Hilbert transform and its applications

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science china Mathematics 2008年第12期51卷 2217-2230页

作者： YANG LiHua School of Mathematics and Computing science, sun yat-sen university, guangzhou 5102.5, china School of Mathematics and Computing science Sun Yat-Sen University Guangzhou 510275 China

In this paper, a new distribution space is constructed and the definition of the classical Hilbert transform is extended to it. It is shown that is the biggest subspace of on which the extended Hilbert transform is a homeomorphism and both the classical Hilbert transform for L p functions and the circular Hilbert transform for periodic functions are special cases of the extension. Some characterizations of the space are given and a class of useful nonlinear phase signals is shown to be in . Finally, the applications of the extended Hilbert transform are discussed.

关键词： Hilbert transform distribution time-frequency analysis 44A15 46F12

Vortex genesis over the Bay of Bengal in spring and its role in the onset of the Asian Summer Monsoon

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science china Earth sciences 2011年第1期54卷 1-9页

作者： WU GuoXiong1, GUAN Yue1,2, WANG TongMei3, LIU YiMin1, YAN JingHui4 & MAO JiangYu1 1 State Key Laboratory of Numerical Modeling for atmospheric sciences and Geophysical Fluid Dynamics (LASG), Institute of atmospheric Physics, Chinese Academy of sciences, Beijing 100029, china 2Graduate university of Chinese Academy of sciences, Beijing 100049, china 3department of atmospheric science, sun yat-sen university, guangzhou 5102.5, china 4National Climate Center, china Meteorological Administration, Beijing 100080, china 1. State Key Laboratory of Numerical Modeling for atmospheric sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. Department of Atmospheric Science Sun Yat-Sen University Guangzhou 510275 China4. National Climate Center China Meteorological Administration Beijing 100080 China

Physical processes associated with onset of the 1998 Asian summer monsoon were examined in detail using multi-source datasets. We demonstrated that strong ocean-atmosphere-land interaction in the northern Indian Ocean and tropical Asian area during spring is a fundamental factor that induces the genesis and development of a monsoon onset vortex over the Bay of Bengal (BOB), with the vortex in turn triggering onset of the Asian summer monsoon. In spring, strong surface sensible heating over India and the Indochina Peninsula is transferred to the atmosphere, forming prominent in situ cyclonic circulation, with anticyclonic circulations over the Arabian Sea and northern BOB where the ocean receives abundant solar radiation. The corresponding surface winds along the North Indian Ocean coastal areas cause the ocean to produce the in situ offshore currents and upwelling, resulting in sea surface temperature (SST) cooling. With precipitation on the Indochina Peninsula increasing from late April to early May, the offshore current disappears in the eastern BOB or develops into an onshore current, leading to SST increasing. A southwest-northeast oriented spring BOB warm pool with SST >31°C forms in a band from the southeastern Arabian Sea to the eastern BOB. In early May, the Somali cross-equatorial flow forms due to the meridional SST gradient between the two hemispheres, and surface sensible heat over the African land surface. The Somali flow overlaps in phase with the anticyclone over the northern Arabian Sea in the course of its inertial fluctuation along the equator. The convergent cold northerlies on the eastern side of the anticyclone cause the westerly in the inertial trough to increase rapidly, so that enhanced sensible heat is released from the sea surface into the atmosphere. The cyclonic vorticity forced by such sensible heating is superimposed on the inertial trough, leading to its further increase in vorticity strength. Since atmospheric inertial motion is destr

关键词： air-sea interaction spring BOB warm pool monsoon onset vortex inertial oscillation Asian summer monsoon onset

Interferon-α enhances sensitivity of human osteosarcoma U2OS cells to doxorubicin by p53-dependent apoptosis

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Acta Pharmacologica Sinica 2007年第11期28卷 1835-1841页

作者： Xiang-wei YUAN~2,Xiao-feng ZHU~(3,5),Xiu-fang HUANG~4,Pu-yi SHENG~2,Ai-shan HE~2,Zi-bo YANG~2,Rong DENG~3,Gong-kanFENG~3,Wei-ming LIAO~(2,5)~2 department of Orthopedic Surgery,The First Affiliated Hospital,sun yat-sen university,guangzhou 510080,china ~3 State Key Laboratoryof Oncology in South china,Cancer Center,sun yat-sen university,guangzhou 510060,china ~4 department of Pathology,The AffiliatedJiangmen Hospital,sun yat-sen university,Jiangmen 529030,china department of Orthopedic Surgery The First Affiliated Hospital Sun Yat-sen University Guangzhou 510080 China State Key Laboratory of Oncology in South china Cancer Center Sun Yat-sen University Guangzhou 510060 China department of Pathology The Affiliated Jiangmen Hospital Sun Yat-sen University Jiangmen 529030 China

Aim:To determine whether interferon-α(IFNα) can enhance doxorubicinsensitivity in osteosarcoma cells and its molecular ***:Cellviability was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide *** was studied using Flow cytometry analysis,Hoechst33258 staining,DNA fragmentation assay,as well as the activation ofcaspase-3 and poly (ADP-ribose) *** expression was detectedby Western *** dependence of p53 was determined using ***:IFNα increased doxorubicin-induced cytotoxicity to a muchgreater degree through apoptosis in human osteosarcoma p53-wild U2OS cells,but not p53-mutant MG63 ***α markedly upregulated p53,Bax,Mdm2,andp21,downregulated Bcl-2,and activated caspase-3 and PARP cleavage in re-sponse to doxorubicin in U2OS ***,the siRNA-mediated silencing ofp53 significantly reduced the IFNα/doxorubicin combination-induced cytotoxic-ity and PARP ***:IFNα enhances the sensitivity of humanosteosarcoma U2OS cells to doxorubicin by p53-dependent *** propercombination with IFNα and conventional chemotherapeutic agents may be a ra-tional strategy for improving the treatment of osteosarcoma with functional p53.

关键词： Interferon-α doxorubicin apoptosis p53 osteosarcoma

A provable secure fuzzy identity based signature scheme

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science china(Information sciences) 2012年第9期55卷 2139-2148页

作者： WANG ChangJi 1,2 1 School of Information science and Technology,sun yat-sen university,guangzhou 5102.5,china 2 Guangdong Province Information Security Key Laboratory,sun yat-sen university,guangzhou 5102.5,china 1. School of Information science and Technology Sun Yat-sen University Guangzhou 510275 China2. Guangdong Province Information Security Key Laboratory Sun Yat-sen University Guangzhou 510275 China

To use biometrics identities in an identity based encryption system,Sahai and Waters first introduced the notion of fuzzy identity based encryption(FIBE) in *** et *** it to digital signature and introduced the concept of fuzzy identity based signature(FIBS) in 2008,and constructed an FIBS scheme based on Sahai and Waters's FIBE *** this paper,we further formalize the notion and security model of FIBS scheme and propose a new construction of FIBS scheme based on bilinear *** proposed scheme not only provides shorter public parameters,private key and signature,but also have useful structures which result in more efficient verification than that of Yang et al.'s FIBS *** proposed FIBS scheme is proved to be existentially unforgeable under a chosen message attack and selective fuzzy identity attack in the random oracle model under the discrete logarithm assumption.

关键词： identity based cryptosystem fuzzy identity based encryption fuzzy identity based signature

Assessment of the fused image of multispectral and panchromatic images of SPOT5 in the investigation of geological hazards

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science china(Technological sciences) 2008年第S2期51卷 144-153页

作者： KANG TingJun,ZHANG XinChang & WANG HaiYing department of Remote sensing and GIS Engineering,sun yat-sen university,guangzhou 5102.5,china department of Remote sensing and GIS Engineering Sun Yat-sen University Guangzhou 510275 China

The investigated area in this paper is located on the northern mountain in guangzhou *** is characterized by high relief and *** and pan Images of SPOT5 were used as the remote sensing data source,and high-pass filtering(HPF),Brovery transform(BT),intensity-hue-saturation(IHS),principal component analysis(PCA) and the modified IHS(MIHS) methods were adopted for image ***,a comparison has been made between the entire fused images and the original multispectral *** evaluation and objective evaluation(entropy,average gradient,correlation coefficient,distribution of gray) have been adopted to assess the quality of the fused *** regional geological survey has been taken to find the interpretation *** show that the MIHS is the best image fusion method for geological hazards interpretation,and the fused image can provide abundant textural and spectral information for easy interpretation of such geological hazards as collapse,landslip,and debris flow.

关键词： geological hazard remote sensing image fusion SPOT5

Chemical weathering and chemical runoffs in the seashore granite hills in South china

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science china Earth sciences 2010年第8期53卷 1195-1204页

作者： GAO QuanZhou & TAO Zhen School of Geography and Planning, sun yat-sen university, guangzhou 5102.5, china 1. School of Geography and Planning Sun Yat-sen University Guangzhou 510275 China

Surface runoffs and the contents of major ions and dissolved silicon were surveyed and analyzed based on weekly sampling for one year in a granite watershed of Zhuhai City, Guangdong Province. The results demonstrated that the slope runoff played an essential role in feeding the rivulet during precipitation, whereas the groundwater was more important for the rivulet in the non-raining stages. Dissolved silicon, Na+, HCO3-, and Clions constituted the major chemical components of the rivulet water. atmospheric CO2 and H2SO4 sourced from the oxidation of pyrite were the main erosive mediums in the natural chemical weathering. Natural chemical weathering, the wet and dry deposition of sea-salt, and acids precipitation contributed approximately equal shares of anions to the rivulet water. The ratio of NO3- to SO42- was more than 1.0 in the runoff of the studied seashore watershed, whereas it is less than 1.0 in the Xijiang River that is adjacent to the study area. This implied that the chemical composition of runoff is controlled mainly by the differences in atmospheric acid precipitation caused by human activities and lithology within the catchments under the same bio-climate zone. The CO2 flux consumed by the rock chemical weathering processes within the seashore granite watershed in South china was (0.35-1.37)×105 mol km-2 a-1.

关键词： chemical weathering granite ion sea-salt acid deposition CO2

MANIFOLDS WITH POINTWISE PINCHED RICCI CURVATURE

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Acta Mathematica Scientia 2010年第3期30卷 819-829页

作者：顾会玲 department of Mathematics Sun Yat-sen University

In this article, the author proves a compactness result about Riemannian manifolds with an arbitrary pointwisely pinched Ricci curvature tensor.

关键词： Ricci pinching condition Yamabe flow asymptotic behavior

Linearly time-varying channel estimation and training power allocation for OFDM/MIMO systems using superimposed training

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science china(Information sciences) 2011年第7期54卷 1456-1470页

作者： ZHANG Han 1,DAI XianHua 2 & Pan DaRu 1 1 School of Physics and Telecommunication Engineering,South china Normal university,guangzhou 510006,china 2 department of Information science and Technology,sun yat-sen university,guangzhou 510026,china 1. School of Physics and Telecommunication Engineering South China Normal University Guangzhou 510006 China2. Department of Information Science and Technology SUN Yat-sen University Guangzhou 510026 China

We address the problem of estimating the linearly time-varying (LTV) channel of orthogonal frequency division multiplexing (OFDM)/multiple-input multiple-output (MIMO) systems using superimposed training (ST).The LTV channel is modeled by truncated discrete Fourier *** on this model,a two-step approach is adopted to estimate the LTV channel over multiple OFDM *** also present performance analysis of the channel estimation and derive a closed-form expression for the channel estimation *** is shown that the estimation variances,unlike that of the conventional ST-based schemes,approach to a fixed lower-bound as the training length increases,which is directly proportional to information-pilot power *** wireless communication systems with a limited transmission power,we optimize the ST power allocation by maximizing the lower bound of the average channel *** results show that the proposed approach outperforms the frequency-division multiplexed training schemes.

关键词： OFDM/MIMO systems linearly time-varying channel estimation superimposed training training power allocation

An adaptive spatial clustering method for automatic brain MR image segmentation

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Progress in Natural science:Materials International 2009年第10期19卷 1373-1382页

作者： Jingdan Zhang,Daoqing Dai Center for Computer Vision and department of Mathematics,sun yat-sen(Zhongshan) university,guangzhou 5102.5,china [a]Center for Computer Vision and department of Mathematics Sun Yat-Sen (Zhongshan) University Guangzhou 510275 China

In this paper,an adaptive spatial clustering method is presented for automatic brain MR image segmentation,which is based on a competitive learning algorithm-self-organizing map(SOM).We use a pattern recognition approach in terms of feature generation and classifier ***,a multi-dimensional feature vector is constructed using local spatial ***,an adaptive spatial growing hierarchical SOM(ASGHSOM) is proposed as the classifier,which is an extension of SOM,fusing multi-scale segmentation with the competitive learning clustering algorithm to overcome the problem of overlapping grey-scale intensities on boundary ***,an adaptive spatial distance is integrated with ASGHSOM,in which local spatial information is considered in the clustering process to reduce the noise effiect and the classification *** proposed method is validated by extensive experiments using both simulated and real MR data with varying noise level,and is compared with the state-of-the-art algorithms.

关键词： Self-organizing map Growing hierarchical SOM Adaptive spatial distance Image segmentation MR images