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Optical pulse compression using a nonlinear optical loop mirror constructed from dispersion decreasing fiber

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science china(Technological sciences) 2004年第1期47卷 33-50页

作者： CAO Wenhua & LIU Songhaoschool of information, Wuyi university, Jiangmen 529020, china school for information and Optoelectronic science and engineering, South china normal university, Guangzhou 510631, china 1. school of information Wuyi University 529020 Jiangmen China 2. school for information and Optoelectronic science and engineering South China Normal University 510631 Guangzhou China

A novel scheme to compress optical pulses is proposed and demonstrated numerically, which is based on a nonlinear optical loop mirror constructed from dispersion decreasing fiber (DDF). We show that, in contrast to the conventional soliton-effect pulse compression in which compressed pulses are always accompanied by pedestals and frequency chirps owning to nonlinear effects, the proposed scheme can completely suppress pulse pedestals and frequency chirps. Unlike the adiabatic compression technique in which DDF length must increase exponentially with input pulsewidth, the proposed scheme does not require adiabatic condition and therefore can be used to compress long pulses by using reasonable fiber lengths. For input pulses with peak powers higher than a threshold value, the compressed pulses can propagate like fundamental solitons. Furthermore, the scheme is fairly insensitive to small variations in the loop length and is more robust to higher-order nonlinear effects and initial frequency chirps than the adiabatic compression technique.

关键词： dispersion decreasing fiber (DDF), optical pulse compression, optical solitons.

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 361021,china 2.school of information science and engineering,Southeast university,Nanjing 210096,china 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 2m,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

Notifiable infectious disease surveillance with data collected by search engine

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Journal of zhejiang university-science C(Computers and Electronics) 2010年第4期11卷 241-248页

作者： Xi-chuan ZHOU1,Hai-bin SHEN2 (1Department of information science and Electronic engineering,zhejiang university,Hangzhou 310027,china) (2school of Electrical engineering,zhejiang university,Hangzhou 310027,china) Department of information science and Electronic engineering Zhejiang University Hangzhou China school of Electrical engineering Zhejiang University Hangzhou China

Notifiable infectious diseases are a major public health concern in china,causing about five million illnesses and twelve thousand deaths every *** detection of disease activity,when followed by a rapid response,can reduce both social and medical impact of the *** aim to improve early detection by monitoring health-seeking behavior and disease-related news over the ***,we counted unique search queries submitted to the Baidu search engine in 2008 that contained disease-related search *** we counted the news articles aggregated by Baidu's robot programs that contained disease-related *** found that the search frequency data and the news count data both have distinct temporal association with disease *** adopted a linear model and used searches and news with 1–200-day lead time as explanatory variables to predict the number of infections and deaths attributable to four notifiable infectious diseases,i.e.,scarlet fever,dysentery,AIDS,and *** the search frequency data and news count data,our approach can quantitatively estimate up-to-date epidemic trends 10–40 days ahead of the release of Chinese Centers for Disease Control and Prevention(Chinese CDC)*** approach may provide an additional tool for notifiable infectious disease surveillance.

关键词： Notifiable infectious diseases Disease surveillance Search engine

Identification of Semen Celosiae and Cockscomb Flower Using Continuous Wavelet Transform with FTIR

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稀有金属材料与工程 2006年第S3期 614-616页

作者： Changjiang Zhang~1 Cungui Cheng~2 (1.College of Mathematics,Physics and information engineering,zhejiang normal university,jinhua 321004,china) (2.College of Chemistry and Life science,zhejiang normal university,jinhua 321004,china)

Infrared spectra of semen celosiae and cockscomb flower can be obtained directly,quickly and accurately employing Fourier transform infrared spectroscopy (FTIR) with OMN1 *** wavelet transform (CWT) is employed to zoom in local region of infrared spectra of semen celosiae and cockscomb *** difference of infrared spectra between semen celosiae and cockscomb flower is greatly *** rate is greatly improved. Daubechies wavelet is used as mother *** is implemented to the infrared spectra of semen celosiae and cockscomb *** difference between semen celosiae and cockscomb flower is observed at all scales in the continuous wavelet *** optimal scale is selected to identify semen celosiae and cockscomb *** results show that it is effective to apply CWT on the basis of FTIR to identify traditional Chinese medicinal materials,which are the same general but different species.

关键词： semen celosiate cockscomb flower FTIR CWT Chinese medical material

Bifurcations of travelling wave solutions for two generalized Boussinesq systems

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science china Mathematics 2008年第9期51卷 1577-1592页

作者： LI JiBin1,2 1 Department of Mathematics, zhejiang normal university, jinhua 321004, china 2 Department of Mathematics, Kunming university of science and Technology, Kunming 650093, china Department of Mathematics Zhejiang Normal University Jinhua 321004 China Department of Mathematics Kunming University of Science and Technology Kunming 650093 China

Using the methods of dynamical systems for two generalized Boussinesq systems, the existence of all possible solitary wave solutions and many uncountably infinite periodic wave solutions is obtained. Exact explicit parametric representations of the travelling solutions are given. To guarantee the existence of the above solutions, all parameter conditions are determined.

关键词： nonlinear wave bifurcation solitary wave exact explicit solution generalized Boussinesq system 34C37 34C23 74J30 58Z05

Hydrothermal Synthesis Ultralong Single-crystal Sb_2S_3 Nanowires

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Journal of Wuhan university of Technology(Materials science) 2010年第3期25卷 411-414页

作者：刘运 school of Electric and information engineering Shaanxi University of Science and Technology

This paper describes an ethylene glycol（EG）-assisted approach to the ultralong Sb2S3 nanowires,formed by a simple hydrothermal reaction between SbCl3 and Na2S in the presence of distilled *** electron microscopy and scanning electron microscopy studies indicate that these Sb2S3 nanowires possess a diameter around 200 nm and length up to 100 μ ***-resolution transmission electron microscopy and selected area electron diffraction studies reveal that each Sb2S3 nanowire is a single-crystal along the [001] *** possible formation mechanism of the nanowires was *** effects of volume ratio of ethylene glycol/water on the morphology of Sb2S3 nanowires were also *** reflectance spectrum result shows that the final products have an apparent blue shift by quantum size effect.

关键词： nanostructures chemical synthesis electron microscopy electron diffraction

MMSE relay precoding schemes based on quantization error compensation for multi-relay system

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science china(information sciences) 2010年第12期53卷 2548-2556页

作者： LI Ting 1,2 & YANG LuXi 2 1 College of Communication and information engineering,Nanjing university of Posts and Telecommunications,Nanjing 210003,china 2.school of information science and engineering,Southeast university,Nanjing 210096,china 1. College of Communication and information engineering Nanjing University of Posts and Telecommunications Nanjing 210003 China2. School of Information Science and Engineering Southeast University Nanjing 210096 China

In order to deal with the performance degradation resulting from the quantization error,this paper introduces the statistics of Grassmannian codebook's quantization error into relay precoding design for multirelay *** on the two-step MMSE optimization algorithm for relay precoding and receiver equalizing with full feedback under QoS requirements,we first propose a limited feedback two-step MMSE optimization scheme for relay precoding and receiver equalizing with quantization error compensation,and then we propose a limited feedback joint MMSE optimization scheme for relay precoding and receiver equalizing with quantization error compensation subject to a global power constraint at the output of *** results show that the proposed joint MMSE optimization scheme with quantization error compensation has a much lower bit-error rate than the two-step MMSE optimization scheme with quantization error compensation and the joint MMSE optimization scheme without quantization error compensation.

关键词： multi-relay precoding limited feedback minimum mean square error

New multisoliton solutions of the(2+1)-dimensional dispersive long wave equations

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Communications in Nonlinear science and Numerical Simulation 2001年第3期6卷 178-182页

作者： Jiefang ZHANG and Ping HAN Institute of Nonlinear Physics, zhejiang normal university, jinhua 321004, china College of engineering, zhejiang Ocean university, Zhoushan 316004, china Institute of Nonlinear Physics Zhejiang Normal University Jinhua 321004 China College of engineering Zhejiang Ocean University Zhoushan 316004 China

Using the extension homogeneous balance method, we have obtained a nonlinear transformation to simplify the (2+1)-dimensional dispersive long wave equations into a linear partial differential equation, and found some ... 详细信息

关键词： multisoliton (2+1)-dimensions dispersive long wave equations

Transition of Growth Mode in Homoepitaxy on Metal Surface

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Communications in Theoretical Physics 2007年第7期48卷 175-178页

作者： WU Li-Li LU Hang-Jun WU Feng-Min College of Mathematics and Physics,information engineering,zhejiang normal university,jinhua 321004,china College of Mathematics and Physics Information Engineering Zhejiang Normal University

The process of the multilayer growth of Pt on Pt(111)is studied by using a Monte Carlo model with realisticphysical *** effects of the substrate temperature,the ES barrier,and the deposition rate on the growthmode have been *** transitions of the surface roughness from oscillatory to non-oscillatory behaviorand then back to oscillatory behavior are observed while increasing the substrate temperature from 270 K to 620 *** found that the growth mode depends strongly on ES barrier over the whole temperatures and the deposition rate ofatoms effectively affects the growth *** simulation results are consistent with many experimental observationsfor homoexpitaxy on a Pt(111)substrate.

关键词： growth mode transition Monte Carlo simulation surface roughness oscillation