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Science china Chemistry 2010年第8期53卷 1634-1640页

作者： GAO HaiYang1,2.HU Hao1 & WU Qing1,2.1Institute of Polymer Science,school of Chemistry and Chemical Engineering,sun {2.-sen (zhongshan) University,guangzhou 5102.5,china 2.ey Laboratory for Polymeric Composite and Functional Materials of Ministry of Education sun {2.-sen (zhongshan) University,guangzhou 5102.5,china 1. Institute of Polymer Science School of Chemistry and Chemical Engineering Sun Yat-Sen (Zhongshan) University Guangzhou 510275 China2. Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education Sun Yat-Sen (Zhongshan) University Guangzhou 510275 China

A novel bis(α-alkyloxoimine) titanium(IV) complex was synthesized and used as a catalyst precursor to catalyze homo-and copolymerization of ethylene and *** titanium complex activated with methylalumoxane exhibits good activities for the homopolymerizations of ethylene and norbornene under high temperature to produce high-molecular-weight linear polyethylene and vinyl-type polynorbornene,***-norbornene copolymers with high molecular weight can also be produced by this *** incorporation of norbornene from 0 to 76 mol% in the copolymers can be controlled by varying the charged norbornene.13C NMR analyses show that the microstructures of the ethylene-norbornene copolymers with low norbornene incorporation are predominantly alternated and isolated norbornene units,while those with high norbornene incorporation are random polymers containing long norbornene sequences.

关键词： catalyst ethylene norbornene polymerization copolymerization

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 {2.-sen University,guangzhou 5102.5,china 2.Guangdong Province Information Security Key Laboratory,sun {2.-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 2.08,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

On the diophantine equation X^2.(1+a^2.Y^4 =-2.

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Science china Mathematics 2010年第8期53卷 2143-2158页

作者： YUAN PingZhi 1 & ZHANG ZhongFeng 2.1 school of Mathematics,South china Normal University,{2. 510631,china 2.school of Mathematics & Computational Science,sun yat-sen University,{2. 5102.5,china 1. school of Mathematics South China Normal University Guangzhou 510631 China2. School of Mathematics & Computational Science Sun Yat-Sen University Guangzhou 510275 China

Let a≥1 be an *** this paper,we will prove the equation in the title has at most three positive integer solutions.

关键词： algebraic approximations continued fractions elliptic curves quartic equations

Steganalysis of stochastic modulation steganography

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Science in china(Series F) 2006年第3期49卷 273-285页

作者： HE Junhui1,2.& HUANG Jiwu1,2.1. school of Information Science and Technology, sun {2.-sen University, guangzhou 5102.5, china 2. Guangdong Province Key Laboratory of Information Security, guangzhou 5102.5, china 1. school of Information Science and Technology Sun Yat-sen University Guangzhou 510275 China 2. Guangdong Province Key Laboratory of Information Security Guangzhou 510275 China

Stochastic modulation steganography embeds secret message within the cover image by adding stego-noise with a specific probabilistic distribution. No method is known to be applicable to the estimation of stochastic modulation steganography. By analyzing the distributions of the horizontal pixel difference of images before and after stochastic modulation embedding, we present a new steganalytic approach to accurately estimate the length of secret message in stochastic modulation steganography. The pro- posed method first establishes a model describing the statistical relationship among the differences of the cover image, stego-image and stego-noise. In the case of stegoimage-only steganalysis, rough estimate of the distributional parameters of the cover image＇s pixel difference is obtained with the use of the provided stego-image. And grid search and Chi-square goodness of fit test are exploited to estimate the length of the secret message embedded with stochastic modulation steganography. The experimental results demonstrate that our new approach is effective for steganalyzing stochastic modulation steganography and accurately estimating the length of the secret message.

关键词： information hiding steganography steganalysis stochastic modulation statistical distribution models of difference.

Calibration based universal JPEG steganalysis

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Science in china(Series F) 2009年第2期52卷 260-268页

作者： HUANG FangJun1,2.& HUANG JiWu1,2.1 school of Information Science and Technology,sun {2.-sen University,guangzhou 5102.5,china 2.Guangdong Key Lab. of Information Security Technology,sun {2.-sen University,guangzhou 5102.5,china school of Information Science and Technology Sun Yat-Sen University Guangzhou 510275 China Guangdong Key Lab. of Information Security Technology Sun Yat-Sen University Guangzhou 510275 China

For steganalysis of JPEG images, features derived in the embedding domain appear to achieve a preferable performance. However, with the existing JPEG steganography, the minor changes due to the hidden secret data are not easy to be explored directly from the quantized block DCT （BDCT） coefficients in that the energy of the carrier image is much larger than that of the hidden signal. In this paper, we present an improved calibration-based universal JPEG steganalysis, where the microscopic and macroscopic calibrations are combined to calibrate the local and global distribution of the quantized BDCT coefficients of the test image. All features in our method are generated from the difference signal be- tween the quantized BDCT coefficients of the test image and its corresponding microscopic calibrated image, or calculated as the difference between the signal extracted from test image and its corresponding macroscopic calibrated image. The extracted features will be more effective for our classification. Moreover, through using the Markov empirical transition matrices, both magnitude and sign dependencies along row scanning and column scanning patterns existed in intra-block and inter-block quantized BDCT coefficients are employed in our method. Experimental results demonstrate that our proposed scheme outperforms the best effective JPEG steganalyzers having been presented.

关键词： JPEG steganography steganalysis microscopic calibration macroscopic calibration

Twisted Ate pairing on hyperelliptic curves and applications

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Science china(Information Sciences) 2010年第8期53卷 1528-1538页

作者： ZHANG FangGuo 1,2.1 school of Information Science and Technology, sun {2.-sen University, guangzhou 5102.5, china 2.Guangdong Key Laboratory of Information Security Technology, guangzhou 5102.5, china 1. school of Information Science and Technology Sun Yat-Sen University Guangzhou 510275 China2. Guangdong Key Laboratory of Information Security Technology Guangzhou 510275 China

In this paper we show that the twisted Ate pairing on elliptic curves can be generalized to hyperelliptic curves, and give a series of variations of the hyperelliptic Ate and twisted Ate pairings. Using the hyperelliptic Ate pairing and twisted Ate pairing, we propose a new approach to speeding up the Weil pairing computation. For some hyperelliptic curves with high degree twist, computing Weil pairing by our approach may be faster than Tate pairing, Ate pairing, and all other known pairings.

关键词： Ate pairing Weil pairing hyperelliptic curves pairing-based cryptosystems twisted curves

Investigation of thermoluminescence in Li_2._4O_7 phosphors doped with Cu, Ag and Mg

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Science china(Physics,Mechanics & Astronomy) 2007年第3期50卷 311-320页

作者： XIONG ZhengYe1,2. TANG Qiang2.& ZHANG ChunXiang2.1 College of Science, Guangdong Ocean University, Zhanjiang 52.088, china 2.school of Physics Science and Engineering, {2. yat-sen University, guangzhou 5102.5, china 1. College of Science Guangdong Ocean University Zhanjiang 524088 China 2. school of Physics Science and Engineering Sun Yat-sen University Guangzhou 510275 China

Li2.4O7 （LBO）:Cu,Ag,Mg phosphors have been prepared by the sintering technique. The roles of the Ag and Mg dopants in the phosphors have been studied using the methods of thermoluminescence （TL） glow curves and TL... 详细信息

Li2./sub>B4O7 （LBO）:Cu,Ag,Mg phosphors have been prepared by the sintering technique. The roles of the Ag and Mg dopants in the phosphors have been studied using the methods of thermoluminescence （TL） glow curves and TL 3D spectra. The results indicated that proper concentrations of Ag and Mg can enhance the TL of LBO:Cu. It was also indicated that the intensity of TL peak at 130℃ is reduced with the in- creasing Ag concentration, and enhanced with the increasing Mg concentration. From the TL 3D spectra, three emission bands （λ1 = 42. nm, λ2.= 380 nm, λ3 = 350 nm） were observed: the intensity of low energy emission band is reduced and that of the high energy is enhanced with the increasing dopant Ag; on the contrary, the intensity of low energy emission band is enhanced and that of the high energy one is reduced with the increasing dopant Mg.

关键词： thermoluminescence spectra borate lithium

Progress of Lyman-alpha-based beam emission spectroscopy(Ly BES)diagnostic on the HL-2. tokamak

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Plasma Science and Technology 2024年第3期26卷 118-125页

作者：周艺轩余羿许敏柯锐聂林徐皓赵光义刘灏袁子豪肖晨雨李继全肖池阶 the HL-2. Team Southwestern Institute of Physics Chengdu 610041People's Republic of China Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082People's Republic of China State Key Laboratory of Nuclear Physics and Technology School of PhysicsPeking UniversityBeijing 100871People's Republic of China

An edge Lyman-alpha-based beam emission spectroscopy(LyBES)diagnostic,using a heating NBI(neutral beam injection)system,is currently under development on the HL-2. *** 2.-channel edge LyBES,which is intended to measure the density fluctuation in plasma edge(from R=1960 mm to R=2.2. mm)with an improved spatial resolution of 3.3 mm,is a complement to the existing conventional beam emission spectroscopy(BES)*** this article,we introduce the progress of LyBES diagnostic,including the collection optics,the monochromator,and the detector *** reflectance of the collection mirrors is measured to be~82.at 12. nm,and the aberration geometrical radius of the collection optics is tested to be~150μm in the aimed *** linear dispersion of the LyBES monochromator is designed to be~0.09 nm mm^(-1).The bandwidth of the detector system with the 5×10^(7)V A^(-1)preamplifier gain is measured to be~2.0 kHz,and the peak-to-peak noise of the detector system is tested to be~16 *** finalized design,components development and testing of the LyBES diagnostic have been completed at present,and an overall performance of the LyBES diagnostic is to be confirmed in the next HL-2. campaign.

关键词： density fluctuation Ly BES BES vacuum ultraviolet

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,{2. 510006,china 2.Department of Information Science and Technology,sun yat-sen University,{2. 51002.,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

Thermal preconditioning protected cerebellar granule neurons of rats by modulating HSP70 expression

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Acta Pharmacologica Sinica 2004年第4期25卷 60-63页

作者： Li-jun CHEN, Xing-wen SU, Peng-xin QIU, Yi-junHUANG, Guang-mei YAN2.Department of Pharmacology, zhongshan MedicalCollege, sun {2.-sen University, guangzhou 510089, china Department of Pharmacology Zhongshan Medical College Sun YatSen University Guangzhou 510089

AIM: To explore the possibility that expressions of different heat shock proteins (HSPs) are specifically involved in the protection of thermal preconditioning against apoptosis of cerebellar granule neurons (CGNs) induced by repolarization. METHODS: Western blotting was used to detect expressions of HSP2., HSP70, and HSP90 in- duced by thermal preconditioning (TP) in CGNs; reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the expression level of HSP70 mRNA; apoptosis of CGNs was induced by switching culture medium containing KCl 2. mmol/L to one containing KCl 5 mmol/L. RESULTS: No expression of HSP2. in cerebellar granule neurons was observed with TP at 44 oC. Expression of HSP90 was obvious in CGNs both without and with TP at 44 oC for different periods. Expression of HSP70 protein in CGNs was lower with TP at 44 oC for 5 min, but it increased gradually after the period was prolonged to 30, 60, or 90 min. HSP70 mRNA was detected after TP 44 oC for 30, 60, and 90 min and increased gradually with time. HSP70 antisense oligodeoxynucleotides 10 μmol/Lfor 72.h inhibited the protective effects of TP at 44 oC on apoptosis of CGNs induced by repolarization. CONCLUSION: HSP70 is involved in protective effects of thermal preconditioning on apoptosis in cerebellar granule neurons induced by repolarization.

关键词： thermal preconditioning heat heat shock proteins cerebellum neurons apoptosis antisense oligodeoxynucleotides Western blotting