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RST transforms resistant image watermarking based on centroid and sector-shaped partition

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Science china(Information Sciences) 2012年第3期55卷 650-662页

作者： ZHAO Yao1,2*, NI RongRong1,2* & ZHU ZhenFeng1,2* 1Institute of Information Science, beijing jiaotong university, beijing 100044, china 2beijing Key Laboratory of Advanced Information Science and Network Technology, beijing 100044, china Institute of Information Science Beijing Jiaotong University Beijing China beijing Key Laboratory of Advanced Information Science and Network Technology Beijing China

A novel digital watermarking scheme featuring centroid-based sectoring is proposed in this paper. To get higher robustness against geometric attacks, such as rotation, scaling, and translation (RST), a delicate synchronization mechanism was developed and incorporated into the proposed approach. During the process of watermark embedding, the original image was partitioned into sectors based on the image centroid. Synchronization information as well as the message bits is then embedded into these sectors. With the help of the centroid-based sectoring and synchronization information, the proposed approach is capable of restoring the correct sectoring even if it has experienced severe geometric distortion. This attribute ensures the correct recovery of embedded watermarks and contributes to the robustness of the proposed scheme. A series of experiments have been conducted to verify the feasibility and effectiveness of the proposed approach. Experimental results show that the proposed scheme possesses good robustness against RST attacks and considerable robustness against other common image processing attacks.

关键词： digital watermarking geometrical transform attacks RST transforms

The Spectrum of (gv, g, 3, λ)-dDF in Zgv

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Acta Mathematica Sinica,English Series 2010年第2期26卷 377-392页

作者： Xiao Miao WANG Yan Xun CHANG Institute of Mathematics, beijing jiaotong university, beijing 100044, P. R. china Institute of Mathematics Beijing Jiaotong University Beijing P. R. China

In this paper, several recursive constructions for directed difference family and perfectdirected difference family are presented by means of difference matrix and incomplete difference *** the necessary and sufficient conditions for the existence of a (gv, g, 3, λ)-directed differencefamily in Zare established. As a consequence, the necessary and sufficient conditions for the existenceof a cyclic directed group divisible design with block size three and type g~v are obtained.

关键词： directed difference family incomplete difference matrix perfect directed difference family

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交通拥堵发生时车道非同态性变化的仿真分析

系统仿真学报 2006年第5期18卷 1339-1342,1387页

作者：关伟北京交通大学交通运输学院系统工程与控制研究所北京100044

交通系统的状态转移是一个正负反馈交替发生作用的过程。首先提出了同态度量指标、时空差异度指标等新概念用于定性判断交通系统的状态,并在此基础上,建立了一组变参数线性方程用以描述交通系统状态转移的正负反馈交互迭代的过程。最后... 详细信息

交通系统的状态转移是一个正负反馈交替发生作用的过程。首先提出了同态度量指标、时空差异度指标等新概念用于定性判断交通系统的状态,并在此基础上,建立了一组变参数线性方程用以描述交通系统状态转移的正负反馈交互迭代的过程。最后以某城市环路一个路段发生交通拥堵的过程为实例,仿真分析了交通拥堵发生时车道非同态性变化的过程,仿真结果表明提出的模型能较好地反映车道非同态性变化的实际情况。

关键词：交通流模型交通拥堵仿真定性推理

Performance analysis of uplink MIMO MC-CDMA systems based on linear zero-forcing V-BLAST algorithm

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Science in china(Series F) 2008年第9期51卷 1305-1318页

作者： YANG Wei1,2 & YANG Wei1 1 State Key Laboratory of Rail traffic Control and Safety,beijing jiaotong university,beijing 100044,china 2 National Mobile Communications Research Laboratory,Southeast university,Nanjing 210096,china State Key Laboratory of Rail traffic Control and Safety Beijing Jiaotong University Beijing China National Mobile Communications Research Laboratory Southeast University Nanjing China

A structure was proposed for multiple-input-multiple-output multicarrier code divi- sion multiple access （MIMO MC-CDMA） uplink transmission system. Linear zero- forcing V-BLAST （ZF V-BLAST） algorithm and maximum ratio combining （MRC） scheme was applied to the receivers. The average bit error rate （BER） expression was derived on condition that the number of receive antennas was larger than that of transmit antennas and it was verified by simulations. Numerical results show that the number of transmit and receive antennas, as well as the number of sub- carriers, all exert significant effects on the BER performance. The space diversity and frequency diversity show different abilities to improve the BER performance. The MIMO MC-CDMA system based on linear ZF V-BLAST algorithm is capable of achieving better BER performance than that of the conventional MC-CDMA system by reducing the number of transmit antennas or increasing the number of receive antennas.

关键词： bit error rate(BER) multiple-input-multiple-output(MIMO) multicarrier code division multiple access(MC-CDMA) zero-forcing(ZF)

CRITERION FOR JUDGING SATISFACTION OF CONSISTENCY CONDITIONS IN RATE-DEPENDENT CONSTITUTIVE RELATIONS

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Acta Mechanica Solida Sinica 1999年第4期12卷 356-364页

作者： Wang Zhe (College of Civil Engineering and Architecture,Northern jiaotong university,beijing 100044,china) Coll. of Civ. Eng. and Architecture Northern Jiaotong University Beijing 100044 China

Based on irreversible thermodynamics, the criterion for judging the satisfaction of consistency conditions in rate-dependent constitutive relationship is deduced by introducing four basic hypotheses. Formulas for solving internal variables are given. It makes the rate-dependent model applicable no matter whether the consistency conditions can be satisfied or not.

关键词： rate-dependent constitutive relations consistency condition irreversible thermodynamics

Theoretical analysis of polarization properties for tilted fiber Bragg gratings

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Science china(Information Sciences) 2010年第2期53卷 390-397页

作者： XU Ou 1 , LU ShaoHua 2 & JIAN ShuiSheng 2 1 Faculty of Information Engineering, Guangdong university of Technology, Guangzhou 510006, china 2 Institute of Lightwave Technology, beijing jiaotong university, beijing 100044, china Faculty of Information Engineering Guangdong University of Technology Guangzhou China Institute of Lightwave Technology Beijing Jiaotong University Beijing China

The polarization properties for tilted fiber Bragg gratings (TFBGs) are investigated theoretically based on coupled-mode theory and Mueller matrix method. The expression of wavelength-related polarizationdependent loss (PDL) for TFBGs with different tilt angles is derived and calculated. Simulation results are compared, and the results indicate that the polarization capability of TFBGs with 45° angle is stronger than other TFBGs with smaller angles. The degree of polarization for unpolarized light passing TFBGs is also simulated to further evaluate the polarization properties for various tilt angles. In addition, the relationship between physical parameters of a TFBG and its polarization capability is discussed.

关键词： coupled-mode theory degree of polarization (DOP) Mueller matrix method polarization dependent loss (PDL) tilted fiber Bragg gratings

Performances of carbon nanotube field effect transistors with altered channel length

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Science china(Technological Sciences) 2010年第1期53卷 253-256页

作者： FENG Ying,HUANG ShiHua,KANG Kai & FENG YuGuang Institute of Optoelectronic Technology,beijing jiaotong university,beijing 100044,china Institute of Optoelectronic Technology Beijing Jiaotong University Beijing China

The influence of channel length on the performances of carbon nanotube field effect transistors(CNT-FETs) has been *** oxide etching was used to remove approximately a 60 nm layer from the original 100 nm silicon dioxide layer,to thin the dielectric layer of the back *** length of the CNT-FETs was changed along with the etching *** dependence of drain-source current on gate voltage was measured to analyze the performance of the CNT-FETs,including the transconductance,carrier mobility,current ON/OFF ratio,*** results indicate that the devices still keep good quality.

关键词： carbon nanotube field effect transistors mobility buffered oxide etching

Experimental study on drying of typical MSW under incinerator-like conditions

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Science china(Technological Sciences) 2007年第5期50卷 636-643页

作者： ZHANG YanGuo1, CHEN MeiQian2, MENG AiHong1, LI QingHai1 & CHEN YunXuan2 1 Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Tsinghua university, beijing 100084, china 2 school of Mechanical, Electronical and Control Engineering, beijing jiaotong university, beijing 100044, china Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Tsinghua University Beijing China school of Mechanical Electronical and Control Engineering Beijing Jiaotong University Beijing China

In this paper, a series of experiments were conducted to investigate the drying of typical municipal solid wastes (MSW) in a muffle incinerator. From the experimental drying characteristic curves, the effects of temperature on drying process were observed to be more obvious in the low temperature region than in the high tem- perature region in muffle incinerator. At a specified drying temperature, drying time was highly dependent upon the packed waste thickness, having an exponent rela- tion with the thickness. When the drying temperature increased or the thickness of potato bulks was diminished, the maximum drying rate reduced. Based on the first-order reaction, activation energy (Ea), and factor A of potato and cabbage were determined.

关键词： drying, MSW, potato blocks, cabbage stems, temperature, dying rate

Estimates for eigenvalues of Laplacian operator with any order

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Science china Mathematics 2007年第8期50卷 1078-1086页

作者： Fa-en WU~(1+) Lin-fen CAO~2 1 Department of Mathematics,beijing jiaotong university,beijing 100044,china 2 Department of Mathematics,Henan Normal university,Xinxiang 453007,china Department of Mathematics Beijing Jiaotong University Beijing China Department of Mathematics Henan Normal University Xinxiang China

Let D be a bounded domain in an n-dimensional Euclidean space ? n . Assume that $$0 < \lambda _1 \leqslant \lambda _2 \leqslant \cdots \leqslant \lambda _k \leqslant \cdots $$ are the eigenvalues of the Dirichlet Laplacian operator with any order l: $$\left\{ \begin{gathered} ( - \vartriangle )^l u = \lambda u, in D \hfill \\ u = \frac{{\partial u}}{{\partial \vec n}} = \cdots = \frac{{\partial ^{l - 1} u}}{{\partial \vec n^{l - 1} }} = 0, on \partial D \hfill \\ \end{gathered} \right.$$ . Then we obtain an upper bound of the (k+1)-th eigenvalue λ k+1 in terms of the first k eigenvalues. $$\sum\limits_{i = 1}^k {(\lambda _{(k + 1)} - \lambda _i )} \leqslant \frac{1}{n}[4l(n + 2l - 2)]^{\tfrac{1}{2}} \left\{ {\sum\limits_{i = 1}^k {(\lambda _{(k + 1)} - \lambda _i )^{\tfrac{1}{2}} \lambda _i^{\tfrac{{l - 1}}{l}} \sum\limits_{i = 1}^k {(\lambda _{(k + 1)} - \lambda _i )^{\tfrac{1}{2}} \lambda _i^{\tfrac{1}{l}} } } } \right\}^{\tfrac{1}{2}} $$ . This ineguality is independent of the domain D. Furthermore, for any l ? 3 the above inequality is better than all the known results. Our rusults are the natural generalization of inequalities corresponding to the case l = 2 considered by Qing-Ming Cheng and Hong-Cang Yang. When l = 1, our inequalities imply a weaker form of Yang inequalities. We aslo reprove an implication claimed by Cheng and Yang.

关键词： Dirichlet problem eigenvalue estimate Laplacian operator 35P15 58G25