Table of Content

20 August 2007, Volume 13 Issue 4

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Articles

PDEBased Image Inpainting Using a Heat Transfer Model

WANG Shuo-zhong;Kedar Shrestha;QIN Chuan;ZHANG Xin-peng

2007, 13(4):  331-336 . 

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Printed Monopole Antenna with Impedance Bandwidth Exceeding 21∶1

ZHONG Shun-shi;LIANG Xian-ling;ZHANG Li-na;WANG Wei

2007, 13(4):  337-343 . 

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A printed monopole antenna with an extremelywide bandwidth is proposed, which consists of an elliptical monopole patch and a coplanar trapezoid ground plane. A tapered coplanar waveguide (CPW) feeder in the middle of the ground plane is used to feed the monopole. The simulated and experimental results demonstrate that this antenna achieves a ratio bandwidth of 21.6∶1 for VSWR≤2, covering the frequency range from 0.41 to 8.86 GHz. It has good omnidirectional radiation characteristics, with a small area of only about 0.19λl×0.16λl, where λl is the wavelength of the lowest operating frequency.


An Algorithm of Cell Search in Broadband Wireless Access Systems


CHEN Hui-min;GU Lin;JIN Yan-liang;WANG Yong

2007, 13(4):  344-347 . 

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A new algorithm of cell search in broadband wireless access systems based on OFDMA is proposed in the paper. With this algorithm, fast cell search can be achieved using the new hierarchical synchronous sequence instead of the original preamble to accomplish symbol timing, frequency offset estimation and cell ID detection. Synchronous sequence structure is analyzed, and the algorithm of cell search described. Simulation for AWGN channel and TU channel shows that the algorithm not only can increase the number of cell ID but also can improve performance of the preamble. Therefore, reliability and effectiveness of cell search are improved.


Techonology of Atmospheric Path Radiation Remote Sensing Image


LI Xian-hua;SHI Biao;LIU Xue-feng;MAO Jian-hua;ZENG Qi-hong

2007, 13(4):  348-351 . 

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Atmospheric path radiation remote sensing images are based on values of atmospheric path radiation in remote sensing data dependent only on the state of atmosphere but not ground conditions. Although atmospheric path radiation causes interference to observation of the earth, it provides crucial information such as atmospheric transmitting characteristics, atmospheric modification of remotely sensed images, regional atmospheric status, and atmospheric environment quality. Therefore, it is important both in theory and practice to generate atmospheric path radiation images by extracting atmospheric path radiation values from the remote sensing images and the corresponding surface reflectance.


Novel Bidirectional Transmission Configuration of Millimeter-Wave Radio-on-Fiber System Based on Optical Frequency Multiplication


LIN Ru-jian;XIU Ming-lei;QIN Hai-lin

2007, 13(4):  352-356 . 

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A bi-directional transmission configuration based on optical frequency multiplication is presented for millimeter-wave radio-on-fiber systems. At CS, the phase of lightwave is modulated by sweeping sine wave together with basedata. At BS, the input lightwave is divided into two branches composed of periodic optical filter, photodiode and bandpass filter operating at different parameters with relative branch. A millimeter-wave signal modulated by basedata can be generated at one branch, while a reference millimeterwave oscillator is produced at the other. The scheme can minimize CS, does not need a millimeter-wave local oscillator at BS, and can depress link dispersion.


Frequency-Domain Separation of Convolutive Mixtures Using a Single Frequency Bin


FANG Yong;WANG Chao

2007, 13(4):  357-362 . 

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In this paper, a novel frequency domain separation algorithm using only one frequency bin for the convolutive mixtures of sources is proposed. The method is a variation of the double-frequency-bin based separation for convolutive mixtures in which the parameters of short time Fourier transform should be selected appropriately. Since only one frequency bin is used, the proposed method involves neither inconsistency of scale indeterminacy nor permutation indeterminacy between different frequency bins in traditional frequency domain separation of convolutive mixtures. Simulation experiments show validity of the proposed single-frequency-bin based separation algorithm for convolutive mixtures.


Current Status and Trend of Audio Information Retrieval Research


WAN Wang-gen;CHANG Liao-yu;YU Xiao-qing;CUI Bin;LIU Han

2007, 13(4):  363-370 . 

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Audio has become an important digital media transmitted over the network. Retrieval of the audio information from a huge audio database has become an important research topic. From the present situation and the trend in audio information retrieval, we describe and summarize concepts and methods of modern audio information retrieval. Specifically, some key techniques and approaches on contentbased audio information retrieval are discussed.


Intermediate View Synthesis Based on Image Mosaic in Video Conferencing


AN Ping;LIU Zhan-wei;LIU Su-xing;ZHANG Zhao-yang;

2007, 13(4):  371-376 . 

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Intermediate view synthesis is a key technique to realize interactive stereoscopic display. The viewer can obtain a “look around" perception from a synthesized virtual view image by changing the viewpoint. This paper proposes an intermediate view synthesis algorithm based on image mosaic to create the virtual view image by exploiting view interpolation and morphings. The original stereo pairs are first normalized to reduce luminance difference. Based on the asymmetry in the left and right camera views, credible areas are chosen to create the transitional view, exploiting the disparity information. Intermediate view images are created by combining view interpolation and morphing. Experimental results show that the proposed method can provide satisfactory rendering results with lower computation load based on objectbased processing, which can be used in interactive stereoscopic display in video conferencing.


Design and Experiment of XBand Circularly Polarized Rectennas


YANG Xue-xia;XUE Yu-jie

2007, 13(4):  377-382 . 

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An optimization model of the rectenna is proposed based on analysis of the factors influencing conversion efficiency of the rectifying diode using circuit simulation software, and investigation of the receiving antenna and LPF using full-wave electromagnetic field simulation software. A 10GHz-rectenna was designed and manufactured. Experiments were carried out in an anechoic chamber. Measured data agree well with the simulation results. The measured output voltage reaches 2.45 V and the RF-DC conversion efficiency is about 58%. Factors affecting the efficiency of rectenna are summarized and methods for improving rectifying efficiency suggested.


Tapering Shape Function for a Fused Fiber


CHEN Zhen-yi

2007, 13(4):  383-388 . 

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According to the principle of volumeconservation, a differential equation of tapering shape function has been derived for a fused fiber. A closedform solution is obtained under the boundary conditions and from the effective length of the fused zone for the fused tapering process. For different tapering processes with various torches, the tapering shape function can be described by the solution completely, accurately and conveniently. Experimental data in the form of relevant charts show good agreement with the theoretical results. Especially, given the initial length of the fused zone, the solution can predict the diameter distribution of the taper zone for the fused tapering fiber with arbitrary elongating length.


A Review of Application of GIS in Communications


LIU Xue-feng;LI Xian-hua;HE You-bin

2007, 13(4):  389-393 . 

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Geographical information system (GIS) is now widely used in various areas in social activities and in the daily life. Applications of GIS in communications are reviewed in this article. These include GISbased communication network management, mobile communication service using GIS, GISassisted communication maintenance, calculation of base station antenna height and the antenna gain in wireless communication, location of wireless communication base stations, and decision analysis of optical cable selection with assistance of remote sensing and GIS.


Low-Power Mobile Wireless Ad Hoc Networks


SHI Hui-chang;SHEN Ming-hua;CHEN Hui-min;ZHANG Xue-fan

2007, 13(4):  394-399 . 

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Wireless Ad Hoc networks are self-organizing with dynamic topology and rapidly deployable, which has no preexisting communication infrastructure. This paper presents implementation of a low-power mobile wireless Ad Hoc network. The 2.4 GHz low-power wireless communication module satisfies the IEEE 802.15.4 standard and realizes multi-hop communication and self-organizing function. This paper also develops protocol stack of Ad Hoc network that fits the hardware of low-power and low-cost. New protocols can significantly reduce the overhead of the network, and extend node lifetime. A unidirectional-links-aware AODV routing protocol and a wireless Ad Hoc network imitation system based on LAN are proposed. Wireless Ad Hoc network communication protocols based on μC/OS-II real-time operating system are designed and implemented.


Simulation of a Modified Hierarchical LMS Algorithm


SHI Hai;XU Lian-qing;ZHANG Shun-min

2007, 13(4):  400-402 . 

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A modified hierarchical least mean square (HLMS) algorithm is proposed. The response of each sub-filter in the hierarchical level is modified to improve the performance of the HLMS algorithm, making the filtering for each sub-filter possible. Simulation results indicate that the modified HLMS algorithm not only maintains fast convergence, but also provides improvement of the mean square error of the impulse response by one order of magnitude with respect to the original HLMS algorithm under the same conditions.


An Improved BIC Algorithm for Speaker Change Detection


YU Xiao-qing;TAN Hai-ying

2007, 13(4):  403-408 . 

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To detect the voice change of speakers, an improved BIC algorithm is proposed in this paper. The algorithm chooses the segmentation point, and then analyzes the trend to locate the voice changing point of speakers. Precision of the algorithm is 90.2% and the recall rate is 95.8%. Compared with the traditional BIC algorithm, this new algorithm has lower computational complexity, with precision and recall rate improved by 62.5% and 16% respectively.


Wavelength-Separation and Buffer-Sharing Routing in DWDM Optical Packet Switching Nodes


WANG Chun-hua;WANG Guo-dong;LI Li;HUANG Zhao-ming

2007, 13(4):  409-414 . 

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We propose a new routing method called wavelength-separating method in DWDM optical packet switching nodes for two-class priority traffics. Analytical models of the method and a buffer-sharing method with special contention control are derived. The optimized results of the two methods show that the wavelength-separating method achieves a better improvement of the packet loss rate (PLR) than the buffer-sharing method in the case of full wavelength conversion and small output buffer length.


Fabrication and Measurement of D-Shape Fiber and Its Few-Mode Bragg Grating

SHI Zhi-dong;DONG Xiao-peng;TANG Ming-jue;LI Jie

2007, 13(4):  415-420 . 

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Samples of D-shape fiber are fabricated using grinding fiber preform, and Bragg gratings are incurved into these samples. Practical aspects in fabrication and measurements are presented. By deep etching into the core, sensitivity of Bragg wavelength to the refractive index is increased. Changes in resonant wavelength of different modes of the D-shape few-mode fiber Bragg grating with respect to surrounding refractive index and temperature, respectively, are measured. The measured data well agree with simulation results, providing a good base for further research on the sensing surrounding refractive index.


Real-Time Extraction of Moving Finger and Fingertip from Clutter Background


GUAN Ye-peng;PAN Zhi-hao

2007, 13(4):  421-425 . 

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Study of finger pointing gesture is significant due to the fact that pointing gesture is an optimal mode in human computer interaction. Extraction of fingers is a key problem to pointing gesture. Any variation of sensible motion target in scenes can be found and there are some differences between the intensities of R, G and B components in a color image in shadow region. An adaptive background modeling method is developed based on long series multi-frame difference and fusion of RGB color information. Motion targets are extracted from clutter background based on the obtained background. According to the relative spatial position of finger in the image, opening operation of structuring element with an adaptive rectangular shape is adopted to horizontally segment motion targets regions. Finger regions and position of fingertip are then determined. Experimental results show that motion finger and fingertip can be extracted efficiently from clutter background.


Generalized Projective Synchronization of Different Chaotic Systems


LI Guo-hui;ZHOU Shi-ping

2007, 13(4):  426-429 . 

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An effective active backstepping method is applied to projective synchronization of two different chaotic systems. The proposed scheme offers a recursive procedure where active control is designed by selecting a series of Lyapunov functions to quickly stabilize the error system at equilibrium. Numerical simulations for projective synchronization of the Lorenz system and Chen's system demonstrate effectiveness of the method.


Application of Image Compounding in Ultrasonic Lamb Wave Tomography


兰姆波;层析成像;图像合成

2007, 13(4):  430-433 . 

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In Lamb wave tomography, the limitation caused by data acquisition geometry generally results in incomplete projection data, therefore poor reconstruction quality. Image compounding is an effective method to improve the image quality. We apply image compounding in Lamb wave tomography. Incomplete data are acquired on an aluminum plate sample with machined defect using different transducers configurations, and images reconstructed using simultaneous iterative reconstruction technique (SIRT). Three different methods of image compounding are used, which are average compounding, rootmeansquare compounding and geometric mean compounding. The results show that the imaged flaw is visually closer to its real shape, and the reconstruction quality significantly improved after compounding.


Routing Algorithm for WSN Based on Swarm Intelligence Optimization


WANG Chao;WANG Hai-ling;SHI Xiang-yong;GONG Xu

2007, 13(4):  434-438 . 

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We propose a swarm intelligence optimization algorithm based on self-organization of the swarm intelligence optimization algorithm. We set up the routing, introduce the concept of system energy entropy and optimize it with simulation annealing. Simulation experiments show that the proposed algorithm has a fast convergence rate and global energy equilibrium, meeting the wireless sensor network requirements such as limited energy, selforganization, and data domination. It is better than the Directed Diffusion routing protocol, therefore can prolong the network's lifespan.


Information Transmission of Electroencephalogram Signal During Mental Arithmetic


LI Ying-jie;SHI Jing;ZHU Chun-yan;FAN Fei-yan

2007, 13(4):  439-443 . 

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Based on calculation of the complexity of mutual information transmission time series obtained from multi-channel EEG signals, this paper gives the main results of our studies on the characteristics in EEGs from subjects with different cognition levels and under different conditions. These conditions include doing mental arithmetic and resting with eyes closed. Our results show that all experiment conditions, cognition levels and areas of the brain have influences on the value of mutual information complexity of EEG time series. Those with depression problems have a significant lower (P<0.001) complexity under arithmetic task than that under resting conditions. However, the difference in the normal group is not significant. We conclude therefore that the mutual information complexity of EEG time series demonstrates the cognition level of the subjects to some degree.


Time-Frequency Distribution of the Fractional Fourier Transform


CHEN Jun-li;WAN Wang-gen;HUANG Bing;XIE Liao-sha

2007, 13(4):  444-448 . 

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Fractional Fourier transform can be considered as generalization of the Fourier transform. Four basic quadratic signal representations, i.e., signal correlation function, spectral correlation function, Wigner distribution, and ambiguity function, can be interpreted with Fourier transform. A new timefrequency distribution function based on 2D fractional Fourier transform is presented. The distributions have partial time/frequency-lag and partial frequency/time-lag characteristics of signals. Main properties of the distribution function are discussed. Simulations show that the described distribution can detect chirp signal.


Design and Application of LMS Adaptive Filter with LabVIEW


LUO Wei-dong;XIAO Guang-hua;FANG Yong

2007, 13(4):  456-460 . 

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As traditional tools such as Matlab and Simulink are inconvenient to produce application systems, we propose to use LabVIEW to develop adaptive filters based on an LMS algorithm. Experiments show that the obtained filter is valid and has good performance in speech processing.


Self-Similarity and Application of the Frequency Spectra of Fractal Cantor Photonic Crystals

XIAO Zhong-yin;WANG Zi-hua;HU Hong-hong;XU He-ming

2007, 13(4):  461-464 . 

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Self-similarity of the frequency spectra of fractal photonic crystals is studied. The optical transmission matrix method is used to calculate transmittance and reflectance. The result shows that there is obvious self-similarity in Cantor multilayer, resulted from the structural selfsimilarity. Being different from general PBG, this structure has stopbands and is also of defect modes. Factors affecting the stopband characteristic and applications of the structure are also studied.


Network Coding in Decentralized Content Distribution

ZOU Jun-ni;LI Le-yang;TAN Chong

2007, 13(4):  465-470 . 

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Based on the graph theory and finite field operation, this paper introduces the principle of network coding and its applications. For a decentralized content distribution network, three coding mechanisms including uncoded distribution, erasure coding based distribution and network coding based distribution are discussed. The excellent performance of network coding based content distribution is demonstrated with both theoretic analysis and computer simulation experiments. Key issues in practical network coding are presented.


Convergence of End-to-End Rate-Based I-D Congestion Control Algorithm

JIN Yan-liang;YANG Yu-hang;JIANG Yi-fan

2007, 13(4):  471-476 . 

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Efficiency and fairness convergence of endtoend ratebased IncreaseDecrease (ID) congestion control algorithms are studied. Convergence time of different congestion control algorithms is computed. Some effective formulae are developed. The analysis results obtained can provide a guideline for design of the congestion control protocol.


A Survey on Semantic Object Segmentation

LIU Zhi;ZHANG Zhao-yang;

2007, 13(4):  477-484 . 

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Semantic object segmentation is a key technique for many content-based multimedia applications intensively investigated in the last decade. From the application viewpoint, three classes of practical semantic object segmentation approaches are discussed. Specifically, these approaches include realtime automatic object segmentation, non-realtime interactive object segmentation, a prior knowledge based object segmentation. Having analyzed the advantages and drawbacks of each class, we conclude that high-level semantics should be integrated in the semantic object segmentation approaches to further expand its applicability. We also give a preview of the emerging visual attention based semantic object segmentation approaches.

A Space-Time Mapping Technique in a MIMO CDMA System

WU Zhuo;CHEN Hui-min

2007, 13(4):  485-488 . 

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A MIMO-based spacetime signal processing technique, spacetime mapping (STM), is proposed in this paper. The space-time mapping technique, proposed from the viewpoint of reducing correlations in adjacent antennas, can either be on the symbol-level or on the chip-level. Simulation results show that the proposed technique can significantly improve the bit-errorrate (BER) performance of a MIMO CDMA system.