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The study of adsorption gas sensor based carbon nanotube film

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Science china(Technological Sciences) 2005年第4期48卷 372-384页

作者： LI Xin1, LIU Junhua2.& ZHU Changchun1 1. school of electronic and {2. Engineering, Xi’an Jiaotong University, Xi’an 710049, china 2. school of Electric Engineering, Xi’an Jiaotong University, Xi’an 710049, china 1. school of electronic and {2. Engineering Xi’an Jiaotong University 710049 Xi’an China 2. school of Electric Engineering Xi’an Jiaotong University 710049 Xi’an China

The study of gas sensitivity of multi-wall carbon nanotubes (MWNTs), which is deposited by low press chemical vapor deposition (LPCVD), is presented. The results show that the pure MWNTs are not sensitive to the gases measured, while the composite film consisting of the MWNTs and silicon dioxide is sensitive to the methane, the hydrogen and the acetylene. The MWNTs and silicon dioxide composite film have the capacitance characteristic because of the formation of Schottky junctions within the MWNTs. The chemistry adsorption of the gas measured on the surface of the MWNTs affects the space discharge area of the Schottky junction, so that the dielectric constant changes with the gas concentration. That is why the gas is sensed.

关键词： gas sensor, carbon nanotubes, low press chemical vapor deposition, scatter.

Locating the Polar Cap Boundary of Postnoon Sector from Observations of 630.0 nm Auroral Emission at Zhongshan Station

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Wuhan University Journal of Natural Sciences 2002年第1期7卷 59-64页

作者： Liu Li-gang 1, Ai Yong 1, Liu Rui-yuan 2. Yang Hui-gen 2.1. school of electronic {2., Wuhan University, Wuhan 430072. Hubei, china 2. Polar Research Institute of china, Shanghai 2.012., china Wuhan University School of Electronic Information Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***) Polar Research Institute of china Shanghai China (GRID:grid.418683.0) (ISNI:***)

We studied the ground observations of 630.0 nm auroral emission at Zhongshan Station to determine the polar cap boundary with the latitudinal profile of emission intensity. The open-closed field time boundary is assumed to lie at the boundary between polar rain and plasma sheet precipitation. We assume that nonprecipitation-dependent sources of 630.0 nm emission cause a spatially uniform luminosity in the polar cap and that auroral zone luminosity is also spatially uniform. Therefore we determine the location of the polar cap boundary of postnoon sector from the auroral emission data each time by finding the best fit of the observations to a step function in latitude and we produce a time series of the location of the polar cap boundary. The average error of the practice in the paper is less than 0.8 degree.

关键词： polar cap boundary aurora Zhongshan Station

Predictive control and scheduling codesign in network control systems

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控制理论与应用（英文版） 2010年第2期8卷 239-244页

作者： Qing SHEN 1 , 2., Weihua GUI 2., Ying XIONG 2., Chunhua YANG 2.(1.school of Basic Education for Officers, National University of Defense Technology, Changsha Hunan 410003, china {2. of information Science and Engineering, Central South University, Changsha Hunan 410083, china) school of Basic Education for Officers National University of Defense Technology Changsha Hunan China school of information Science and Engineering Central South University Changsha Hunan China

A codesign approach combining predictive control compensation and network scheduling is presented in this paper to overcome the adverse influences of stochastic time delays and packet losses encountered in network-based real-time control systems. The state estimation and control prediction compensation algorithms are used for the random network delays in the feedback and forward channels, and the stability criteria are analyzed. The proper sampling rate is given with network scheduling to meet the desired system performance, while the network-induced delay is tolerated. Simulations show that the codesign approach works well with the bounded network delay.

关键词： Network control system Prediction Scheduling Stability

A numerical study on nonlinear propagation and short-term variability of the migrating diurnal and semidiurnal tides

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Chinese Science Bulletin 2005年第17期50卷 1940-1948页

作者： HUANG Chunming1,2. ZHANG Shaodong1,2.& YI Fan1,2.1. school of electronic {2., Wuhan Universiy, Wuhan 430079, china 2. Key Laboratory of Geospace Environment and Geodesy, Ministry of Education, Wuhan University, Wuhan 430079, china school of electronic {2. Wuhan University Wuhan 430079 China Key Laboratory of Geospace Environment and Geodesy Ministry of Education Wuhan University Wuhan 430079 China

By using a three-dimensional fully nonlinear numerical model in spherical coordinates and taking the linear steady solutions of the migrating diurnal and semidi-urnal tides in January from the Global-Scale Wave Model (GSWM) as the initial values, we simulate the linear and nonlinear propagations of the migrating diurnal and semidi-urnal tides in the atmosphere from the ground to the lower thermosphere. A comparison of our simulations with the results of GSWM is also presented. The simulation results show that affected by the nonlinearity, the migrating diurnal and semidiurnal tides propagating in the middle and upper atmosphere exhibit evident short-term variability. The nonlinear interactions between the migrating tides and the background atmosphere can obviously alter the background wind and temperature fields, which suggests that the nonlin-ear propagations of the migrating diurnal and semidiurnal tides impact significantly on the transient dynamical and thermal structures of the background middle and upper at-mosphere and the nonlinear effect is an important cause of the difference between the results of GSWM and observa-tions.

关键词：大气非线性传播数学模型可变性温度场

A study of constraints on the constitutive relationships of electromagnetic medium based on generally acknowledged truths

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Science china(Physics,Mechanics & Astronomy) 2005年第5期48卷 541-548页

作者： GUO Huiping1, LIU Xueguan1,2. YIN Hongcheng2. CHAO Zengming2.& HUANG Peikang2.1. school of electronics and {2. Engineering, Soochow University, Suzhou 2.502., china 2. National Electromagnetic Scattering Laboratory, Beijing 100854, china 1. school of electronics and {2. Engineering Soochow University 215021 Suzhou China 2. National Electromagnetic Scattering Laboratory 100854 Beijing China

The study of constraints on the constitutive relationships of electromagnetic media is of great importance in the aspects of the medium characteristics analysis, the new article material synthesis and the medium parameters reconstruction, etc. According to the fact that the constitutive relationships should not conflict with the general physical laws, the constraints that the constitutive relationships of electromagnetic medium must satisfy have been summarized in this paper. These constraints include determinacy principle, objectivity principle, causality principle and permission principle. And the parameter constraints of the arbitrary linear homogenous time-invariant medium are obtained following the minimum energy consumption principle. This work provides a new way of ascertaining the constitutive relationships of the electromagnetic medium.

关键词： electromagnetic medium, medium parameter constraint, generally acknowledged truths, energy conservation principle, minimum energy consumption principle.

Precise point positioning and its application in mining deformation monitoring

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中国有色金属学会会刊：英文版 2011年第S3期21卷 499-505页

作者： XU Chang-hui1, 2. WANG Jin-ling2. GAO Jing-xiang1, WANG Jian1, HU Hong1 1. school of Environment and Spatial information, {2. University of Mining and Technology, Xuzhou 2.116, {2. 2. school of Surveying and Spatial information Systems, University of New South Wales, Sydney 2.52. Australia [a] school of Environment and Spatial information China University of Mining and Technology Xuzhou 22116 China [b] school of Surveying and Spatial information Systems University of New South Wales Sydney 2052 Australia

Precise point positioning (PPP)-based deformation monitoring scheme is presented for the use in mining deformation monitoring. Within the solutions of daily observation, outliers are detected and removed to avoid any potential misinterpretation of the results and then the deformation can be extracted by the coordinate differences between the two consecutive solutions. Meanwhile, because of the special location of a rover station in mining areas, the satellite geometry may be insufficient for a reasonable PPP solution, and the multipath impact an also be significant. Therefore, it is necessary to predict the satellite geometry before any daily observation. To evaluate the ability of extracting the deformation using the PPP-based method, various quality measures were introduced. The results of three datasets of the same station show that the precision of deformation monitored by PPP can reach up to cm level and even mm level.

关键词： precise point positioning deformation monitoring outlier identification geometry multipath

Performance analysis of network coding for multicast relay system over Nakagami-m fading channels

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Science china(information Sciences) 2011年第11期54卷 2338-2348页

作者： ZHAO Rui 1,YANG LvXi 2.& HUANG YongMing 2.1 school of information Science and Engineering,Huaqiao University,Xiamen 36102.,{2. 2.school of information Science and Engineering,Southeast University,Nanjing 2.0096,{2. 1. school of information Science and Engineering Huaqiao University Xiamen 361021 China2. School of Information Science and Engineering Southeast University Nanjing 210096 China

The outage probability performance of network coding for multicast relay system is analyzed in Nakagami-m fading *** transmission strategies,i.e.,complex field network coding (CFNC) and amplify-and-forward network coding (AFNC),are applied in the system,and the approximate expressions of outage probability are derived at high SNR and the conclusion is reached that the system diversity gains of two transmission strategies are both 2.,as is verified by numerical *** results also show that CFNC can outperform both AFNC and direct transmission without relay in the performances of system outage probability,sum rate and symbol error ratio.

关键词： multicast relay system network coding outage probability diversity gain

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 Yat-sen University, Guangzhou 5102.5, {2. 2. Guangdong Province Key Laboratory of information Security, Guangzhou 5102.5, {2. 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.

An Overview on Wavelet Software Packages

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Wuhan University Journal of Natural Sciences 2001年第Z1期6卷 593-600页

作者： Fan Qi\|bin 1, Li Hong 2.1. school of Mathematics and Statistics, Wuhan University, Wuhan 430072. china 2. school of electronic information, Wuhan University, Wuhan 430072. china school of Mathematics and Statistics Wuhan University Wuhan China school of electronic {2. Wuhan University Wuhan China

Wavelet analysis provides very powerful problem\|solving tools for analyzing, encoding, compressing, reconstructing, and modeling signals and images. The amount of wavelets\|related software has been constantly multiplying. Many wavelet analysis tools are widely available. This overview represents a significant survey for many currently available packages. It will be of great benefit to engineers and researchers for using the toolkits and developing new software. The beginner to learning wavelets can also get a great help from the review. If you browse around at some of the Internet sites listed in the reference of this paper, you may find more plentiful wavelet resources.

关键词： wavelet transforms image compression matching pursuit lifting MATLAB