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Influence of medium parameters on the characteristic of power limiting based on stimulated Brillouin scattering

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Influence of medium parameters on the characteristic of powe...

A tracking loop based on tightly coupled range and velocity filter equations

2007亚洲光电子会议非线形光学及应用分会场

作者： Huaping Gonga, Zhiwei Lub, Dianyang Linb, Songjiang Liuc aInstitute of opto-electronics, china Jiliang University, Hangzhou, china 310018 bInstitute of opto-electronics , Harbin Institute of Technology , Harbin, china 150001 cDepartment of Physics, Daqing Petroleum Institute, Daqing, china 163318

Adopting noise initiation mode of stimulated Brillion scattering （SBS）, the influence of phonon lifetime and gain coefficient of medium on power limiting characteristic is numerically investigated. By using actual parameters of three media, CCl4, Acetone, and CS2, the waveforms of transmitted pulses are simulated. It shows that, different media have little effect on the front peak of waveform, while have an obvious effect on the height of power limiting platform. When using the medium which has short phonon lifetime and small gain coefficient, the height of power limiting platform is comparatively high. When using the medium which has long phonon lifetime and large gain coefficient, the height of power limiting platform is comparatively low. In experiment, focusing 1064nm, 8ns, 18mJ pulses into these three media respectively, the waveforms of transmitted pulses are obtained. And it is shown that, the experimental results are in good agreement with the conclusions of theoretical simulations.

关键词： stimulated Brillouin scattering optical limiting Brillouin medium

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Science china(Information Sciences) 2012年第4期55卷 898-910页

作者： CUI Wei,TIAN Jing & WU SiLiang School of Information and electronics,Beijing Institute of Technology,Beijing 100081,china School of Information and electronics Beijing Institute of Technology Beijing China

A joint range-velocity closed tracking loop,which is based on tightly coupled range and velocity filter is *** the measured velocity value is adopted in the range tracking loop to modify the velocity and acceleration equations from traditional α-β-γ filter,the tracking loop based on tightly coupled range and velocity filter can not only track the range and the velocity simultaneously,but also improve the range tracking *** experimental results show that the tracking errors about range thermal noise in the proposed loop is lower than those in the traditional loop over 2.2 dB,when filter parameters satisfy least mean-square error ***,with the increase of the filter parameter,the tracking performance of our schemes are improved accordingly.

关键词： α-β-γ filter tracking loop thermal noise tracking error tightly coupled range and velocity equations

Compressive sensing SAR range compression with chirp scaling principle

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Science china(Information Sciences) 2012年第10期55卷 2292-2300页

作者： XIAO Peng,YU Ze & LI ChunSheng School of electronics and Information Engineering,Beihang University,Beijing 100191,china School of electronics and Information Engineering Beihang University Beijing China

Compressive sensing(CS) techniques offer a framework for the detection and allocation of sparse signal with a reduced number of *** paper proposes a novel SAR range compression,namely compressive sensing with chirp scaling(CS-CS),achieving the same range resolution as conventional SAR approach,while using fewer range *** order to realize accurate range cell migration correction(RCMC),chirp scaling principle is used to construct reference matrix for compressive sensing ***,error diagrams are designed for measurement of the performance of CS-CS,and some experiments of using real data are performed to deal with the errors caused by three conditions:SNR,sparsity and sampling.

关键词： synthetic aperture radar compressive sensing range cell migration correction error radar signal processing

Improving Generalization of Fuzzy Neural Network

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International Journal of Minerals,Metallurgy and Materials 1997年第2期11卷 57-59页

作者： ZHENG Deling LI Qing FANG Wei(Information Engineering School, USTB, Beijing 100083, china) (china National electronics Imp. &Exp. Beijing Co.) USTB Beijing China

Explores the generalization error of fuzzy neural network, analyzes the reason for occurrence and presents the equation of calculating error by the confidence interval approach. In addition, a generalization error transfering(GET) method of improving the generalization error is proposed. The simulation experimental results of heating furnance show that the GET scheme is efficient.

关键词： neural network fuzzy system generalization error

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基于纹理特征的超声医学图像检索

天津大学学报（自然科学与工程技术版） 2005年第1期38卷 57-60页

作者：王勇吕扬生天津大学精密仪器与光电子工程学院天津300072

在医学信息学领域,对医学图像物理特征的研究有助于实现图像的自动分析和基于内容的检索.为此,提出一种改进的Gabor纹理特征提取方法.通过超声医学图像的分析获得图像主要的纹理频率和方向特性,以此构成图像纹理特征矢量,降低了图像的... 详细信息

在医学信息学领域,对医学图像物理特征的研究有助于实现图像的自动分析和基于内容的检索.为此,提出一种改进的Gabor纹理特征提取方法.通过超声医学图像的分析获得图像主要的纹理频率和方向特性,以此构成图像纹理特征矢量,降低了图像的纹理特征的维数.用该特征进行基于内容的图像检索,避免了采用Gabor小波在检索中带来的维数危机.通过对五类超声心动图像的检索实验,证明该方法的检准率和检全率较高,检索时间较短,能够取得较为满意的结果.

关键词：超声医学图像纹理特征 Gabor滤波器基于内容检索

High-speed Wave Acquisition and Real Time Data Compression

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High-speed Wave Acquisition and Real Time Data Compression

An Implementation of IP-Phone Gateway

第二届仪器科学与技术国际学术研讨会

作者： Song Guangde Liang Lei College of Precision Instrument and opto-electronics Engineering Tianjin University china

＜正＞ High-speed wave acquisition can be used to realize data compression and acquisition. The data after compression is even distributed based on time to keep the waveform and guarantee the peak value. Such a technique has the wave peak value as the main processing object and at the same time show the wavefonn under limited points restriction. This system uses FPGA （Field Programmable Gate Array）, high-speed A/D converter and dual-port RAM as its core units, the sampling rate can be up to 40Msps. Sampling rate and compression ratio could be determined by writing control word to FPGA through microprocessor.

关键词： Data acquisition Data compression

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计算机工程 2002年第S1期28卷 175-179页

作者： MA Yuanchen, HUANG YongfengDepartment of electronics Engineering, Tsinghua University,Beijing 100084, china Department of electronics Engineering Tsinghua University Beijing 100084 China

To implement voice service over packet-based network (Internet) and TDM-based network (PSTN Public Switched Telephone Network), an IP phone gateway is necessary to transform media stream and convert signaling protocols used over both the two networks. In this article, the architecture of the IP-Phone gateway is described firstly. Then the communications mechanism between functional blocks and multi-thread consideration are presented.

关键词： VoIP PSTN Signaling Media form

Fabrication of multi-sectional TiO_2 nanotube arrays by anodization

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Science china Chemistry 2010年第5期53卷 1067-1072页

作者： LI ShiQi,YIN JianBo & ZHANG GengMin Key Laboratory for the Physics and Chemistry of Nanodevices and Department of electronics,Peking University,Beijing 100871,china Key Laboratory for the Physics and Chemistry of Nanodevices and Department of electronics Peking University Beijing China

We report a facile method to grow multi-sectional TiO2 nanotube arrays consisting of alternating bamboo-shaped and smooth-walled nanotube sections by *** key factors are necessary for obtaining these ***,in order to avoid possible disruptions between the conjoint sections of the nanotube,the distribution of hydrogen ions is suggested not to be fiercely disturbed when switching from the first to the second ***,to avoid the disruption of the nanotube at the joint which results from the disparity in diameters between sections,the direct current voltage is set to be the maximum of the square wave *** newly developed TiO2 nanotube arrays are expected to have potential applications in solar cells,drug release and delivery systems.

关键词： titanium dioxide titania nanotube anodic oxidation

Experts' Knowledge Fusion in Model-Based Diagnosis Based on Bayes Networks

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Journal of Systems Engineering and electronics 2003年第2期14卷 25-30页

作者： Deng Yong & Shi Wenkang School of electronics & Information Technology, Shanghai Jiaotong University, Shanghai 200030, P. R. china School of electronics & Information Technology Shanghai Jiaotong University Shanghai 200030 P. R. China

In previous researches on a model-based diagnostic system, the components are assumed mutually independent. Howerver , the assumption is not always the case because the information about whether a component is faulty or not usually influences our knowledge about other components. Some experts may draw such a conclusion that 'if component m 1 is faulty, then component m 2 may be faulty too'. How can we use this experts' knowledge to aid the diagnosis? Based on Kohlas's probabilistic assumption-based reasoning method, we use Bayes networks to solve this problem. We calculate the posterior fault probability of the components in the observation state. The result is reasonable and reflects the effectiveness of the experts' knowledge.

关键词： Model-based diagnosis Experts' knowledge Probabilistic assumption-based reasoning Bayes networks.