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Wavelength Channel Bandwidth of Wavelength-Selective Devices

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Journal of shanghai univ.rsity(English Edition) 2001年第1期5卷 48-52页

作者： XIAO Yan ping, WU Ya ming school of communication and information engineering, shanghai univ.rsity, shanghai 200072, china school of communication and information engineering Shanghai University Shanghai China

Narrow bandwidth is a crucial factor in a high performance wavelength selective device(WSD). There are many different expressions to estimate bandwidths of many different WSDs. In this paper, we derive an important rule that the differential time delay between two coupling modes is the most important factor deciding the wavelength channel bandwidth for several different WSDs. This rule reveals that larger differential time delay between two coupling modes results in higher discrimination level of the operating wavelength. Based on the rule, a novel design of wavelength selective coupler that has a bandwidth narrower than normal couplers is presented.

关键词： wavelength channel bandwidth wavelength selective device(WSD) differential time delay

A Fast Fractal Image Compression Coding Method

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Journal of shanghai univ.rsity(English Edition) 2001年第1期5卷 57-59页

作者： XU Chang man 1, ZHANG Zhao yang school of communication and information engineering, shanghai univ.rsity, shanghai 200072, china ***

Fast algorithms for reducing encoding complexity of fractal image coding have recently been an important research topic. Search of the best matched domain block is the most computation intensive part of the fractal encoding process. In this paper, a fast fractal approximation coding scheme implemented on a personal computer based on matching in range block's neighbours is *** results show that the proposed algorithm is very simple in implementation, fast in encoding time and high in compression ratio while PSNR is almost the same as compared with Barnsley's fractal block coding .

关键词： neighbour fractal block coding range block,domain block iterated function system

The Absorption Characteristics of Inhomogeneous Double-Clad Fibers

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光学学报 2003年第S1期23卷 70-71页

作者： Hui Zhang Zihua Wang Zhongyin Xiao (school of communication and information engineering, shanghai univ.rsity, shanghai, 200072, P.R.china school of communication and information engineering Shanghai University Shanghai 200072 P.R.China

The absorption characteristics of radially inhomogeneous double-clad fiber (DCF) are investigated firstly with the method of caustic radius, combined with the method of WKBJ. The results are significant for double-cla... 详细信息

关键词： of et In as The Absorption Characteristics of Inhomogeneous Double-Clad Fibers mode DCF for into

Hurst Exponent Analysis of Financial Time Series

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Journal of shanghai univ.rsity(English Edition) 2001年第4期5卷 269-272页

作者： SANG Hong wei, MA Tian, WANG Shuo zhong school of communication and information engineering, shanghai univ.rsity, shanghai 200072, china school of communication and information engineering Shanghai University Shanghai China

Statistical properties of stock market time series and the implication of their Hurst exponents are discussed. Hurst exponents of DJIA (Dow Jones Industrial Average) components are tested using re scaled range analysis. In addition to the original stock return series, the linear prediction errors of the daily returns are also tested. Numerical results show that the Hurst exponent analysis can provide some information about the statistical properties of the financial time series.

关键词： Hurst exponent linear prediction error financial time series

Modeling of human colonic blood flow for a novel artificial anal sphincter system

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Journal of Zhejiang univ.rsity-Science B(Biomedicine & Biotechnology) 2008年第9期9卷 734-738页

作者： Peng ZAN, Guo-zheng YAN, Hua LIU (school of Electronics, information and Electrical engineering, shanghai Jiao Tong univ.rsity, shanghai 200240, china) school of Electronics Information and Electrical Engineering Shanghai Jiao Tong University Shanghai 200240 China zanpeng@***.

A novel artificial anal sphincter system has been developed to simulate the normal physiology of the human anorectum. With the goal of engineering a safe and reliable device, the model of human colonic blood flow has been built and the relationship between the colonic blood flow rate and the operating occlusion pressure of the anorectum is achieved. The tissue ischemia is analyzed based on constitutive relations for human anorectum. The results suggest that at the planned operating occlusion pressure of less than 4 kPa the artificial anal sphincter should not risk the vascularity of the human colon.

关键词： Incontinence Artificial anal sphincter Colonic blood flow Tissue ischemia

A New Shape-Coding Algorithm by Using Wavelet Transform

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Journal of Systems engineering and Electronics 2003年第2期14卷 69-73页

作者： Shi Xuli & Zhang Zhaoyang communication school, shanghai univ.rsity, shanghai 200072, P. R. china communication school Shanghai University Shanghai 200072 P. R. China

In this paper, we propose a new shape-coding algorithm called wavelet-based shape coding (WBSC). Performing wavelet transform on the orientation of original planar curve gives the corners called corner-1 points and end of arcs that belong to the original curve. Each arc is represented by a broken line and the corners called corner-2 points of the broken line are extracted. A polygonal approximation of a contour is an ordered list of corner-1 points, ends of arcs and corner-2 points which are extracted by using the above algorithm. All of the points are called polygonal vertices which will be compressed by our adaptive arithmetic encoding. Experimental results show that our method reduces code bits by about 26% compared with the context-based arithmetic encoding (CAE) of MPEG-4, and the subjective quality of the reconstructed shape is better than that of CAE at the same Dn.

关键词： Wavelet transform Shape coding WBSC MPEG-4 CAE.

Research on improving the QoE of relay users in cooperative communication systems

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The Journal of china universities of Posts and Telecommunications 2009年第6期16卷 1-5页

作者： WANG Liang,XIE Wei-hao,CHEN Hui-min,WU Zhuo Key Laboratory of Specialty Fiber Optics and Optical Access Networks,school of communication and information engineering, shanghai univ.rsity,shanghai 200072,china [a] Key Laboratory of Specialty Fiber Optics and Optical Access Networks school of communication and information engineering shanghai univ.rsity shanghai 200072 china

Customers＇ satisfaction with services is reflected by quality of experience（QoE）.Insofar,most studies on cooperative communication have been focused on improving the QoE of source ***,the improvement of a source user＇s QoE is obtained at cost of degradation of the relay user＇s *** the other hand,cooperative communications can achieve performance similar to that of a conventional multiple-input multiple-output（MIMO） system by forming virtual MIMO ***,to improve the QoE performance of relay users,this article proposes the concept of a belief threshold at the destination user and a new cooperative scheme based on the belief threshold destination（BTD） technique,while without decaying the BER performance of the communication system.

关键词： cooperative communication relay user QoE BTD

A Novel Absorbing Boundary Condition for the Frequency-Dependent Finite-Difference Time-Domain Method

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Journal of shanghai univ.rsity(English Edition) 2001年第2期5卷 111-115页

作者： WANG Tong, ZHANG Wen jun, GE Ren wei, LIU Wei liang school of communication and information engineering, shanghai univ.rsity, shanghai 200072, china school of communication and information engineering Shanghai University Shanghai China

A new absorbing boundary condition (ABC) for frequency dependent finite difference time domain algorithm for the arbitrary dispersive media is presented. The concepts of the digital systems are introduced to the (FD) 2TD method. On the basis of digital filter designing and vector algebra, the absorbing boundary condition under arbitrary angle of incidence are derived. The transient electromagnetic problems in two dimensions and three dimensions are calculated and the validity of the ABC is verified.

关键词： dispersive media FDTD(finite different time domain) absorbing boundary condition digital filter

An Improved MAC Scheme of HORNET Based on Node Structure with Variable Optical Buffer

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光学学报 2003年第S1期23卷 697-698页

作者： Nian Fang, Lutang Wang, Zhaoming Huang school of communication and information engineering, shanghai univ.rsity, P. R. china school of communication and information engineering Shanghai University P. R. China

An improved unslotted CSMA/CA MAC scheme of HORNET based on the node structure with variable optical buffer is reported. It can be used for transmitting high effectively all variable IP packets in the WDM network.

关键词： MAC of CSMA An Improved MAC Scheme of HORNET Based on Node Structure with Variable Optical Buffer on APOC with