Table of Content

21 December 2008, Volume 14 Issue 6

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Articles

Image Classification for Sewer Duct Inspection Using Gabor Filtering

YANG Xiao-qian;WANG Shuo-zhong

2008, 14(6):  551-556 . 

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Gabor filters are widely used in image analysis and computer vision applications. We use a set of multiscale and multiorientation Gabor filters to extract texture features from image blocks of underground sewer duct, and use principal components analysis (PCA) to reduce dimension of the feature vectors. These feature vectors are related to the nature and extend of the damage in the sewerage. Classification of the image blocks is made based on the extracted feature vectors. As the Gabor filters are not orthogonal, suitable parameters should be chosen to minimize redundancy in the extracted image data. The result of k-means clustering verifies the validity of the proposed method. 


New Compact Dual Band Bandpass Filter Using Stepped Impedance Resonators

XU He-ming;XIAO Zhong-yin;HU Hong-hong

2008, 14(6):  557-559 . 

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A new dualband bandpass filter for 2.4/5.2 GHz WLAN systems using two stepped impedance resonators is presented. With a properly coupled structure, this filter appears very compact and easy to fabricate. Measured results show that this filter has very low insertion loss of 0.3 dB at 2.4 GHz and 0.7 dB at 5.2 GHz, and broad fractional bandwidths in both passbands, that is, 30% and 17%, respectively. Measured results are in good agreement with simulation.


Design of Novel Compact Dual Frequency Microstrip Slot Antenna

CHEN Lei;SHEN Wen-hui;ZHAO Guo-hua

2008, 14(6):  560-563 . 

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A novel compact microstrip slot antenna for wireless communication is presented. The antenna has a compact structure and a simple feed method to satisfy technical requirements of the WLAN application. An adjustable Fshaped slot is employed to excite appropriate resonant frequencies at 2.4/5.8 GHz for WLAN. This antenna is characterized by its omni-directional radiation pattern. The gain of the antenna is 3.8~4.5 dBi.


Improved Algorithm for Uplink Timing in Broadband Wireless Access Systems

ZHENG Xiang;CHEN Jian;JIN Yan-liang

2008, 14(6):  564-567 . 

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An improved algorithm of random access channel(RACH)in broadband wireless access systems based on IEEE 802.16e-OFDMA is proposed. By combining the ranging signal in the time domain, the algorithm enhances the SNR of correlation in the frequency domain, and is more robust in the ranging user detection and delay estimation at low SNR. Simulation results show that the proposed algorithm improves the performance of ranging user detection and delay estimation at low SNR, and enhances the performance of edge users. 


Reference Symbol Design of Downlink Based on Pilot in Broadband Wireless Communication


ZHANG Ri-hua;LI Ying-chun;WU Zhuo

2008, 14(6):  568-571 . 

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A kind of reference symbol is designed for downlink based on pilot of broadband wireless communication systems in this paper. The new pilot is made of PN code, orthogonal variable spreading factor（OVSF） code and generalized chirp like/constant amplitude zero auto-correlation(GCL/CAZAC) sequence. Simulation results indicate that the proposed method can restrain the co-channel interference in adjacent sectors and cells. The bit error rate (BER), block error rate (BLER), and throughput of the system are all improved effectively.


Improvement of CQI Feedback Schemes Based on OFDMA System


ZHU Wei-xiao;ZHAO Dong-dong;WU Zhuo

2008, 14(6):  572-576 . 

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In this paper, a new feedback scheme is presented based on comparison of several CQI feedback schemes using OFDMA(orthogonal frequency division multiple access). The number of feedback levels is decreased, while the number of feedback resource block(RB) is increased in each level in order to enrich the feedback information of radio channel. Simulation shows that the new scheme enhances description precision of radio channel and flexibility when it is used under different channel conditions without additional bit cost as compared to some current schemes.


Compact Ultra-Wideband Wide Slot Antenna and the Design of Its Band-Notched Function

LU Yang-zhun;WANG Zi-hua

2008, 14(6):  577-580 . 

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A novel compact wide-slot planar antenna and its extended design with band-notched function are proposed for ultra-wideband (UWB) applications. The antenna is fed by coplanar wave guide (CPW) with an elliptical tuning stub. A symmetric polygonal wide-slot configuration is used to obtain ultra-wideband characteristics. The characteristics of the proposed antenna are investigated both numerically and experimentally. Experimental results show that the impedance bandwidth of the antenna reaches up to 3.2~10.1 GHz for S₁₁≤-10 dB. In addition, by inserting W-shaped slots on the elliptical stub, band-notched function of the antenna is achieved for WLAN (5.150～5.825 GHz) applications.

Design of Miniaturized Planar Spiral Antenna and Its Wideband Balun

ZHU Yu-xiao;ZHONG Shun-shi;XU Sai-qing;ZHANG Li-na

2008, 14(6):  581-584 . 

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This paper introduces a miniaturized planar spiral antenna with a very wide bandwidth. In the frequency range from 0.95 GHz to 15.20 GHz, the measured return loss is less than -10 dB. Good circular polarization performance (axial ratio<4 dB) is obtained between 1.4 GHz and 10.2 GHz. Compared with the conventional spiral antenna, the proposed antenna significantly reduces the size and efficiently broadens the 3 dB beam width to about 130° by adding a conical back cavity beneath the antenna. Moreover, a wideband balun is designed using an exponentially tapered microstrip parallel-line wire. Simulation and experimental results show that the proposed antenna is of good circular polarization and wideband characteristics. 

Sensitivity Analysis of Magneto-optic Modulation Method in Measuring Beat Length of Birefringence Optical Fiber

LIU Shu;SHI Zhi-dong;BAO Huan-huan

2008, 14(6):  585-589 . 

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Based on Faraday effects in birefringence optical fiber, we study the influence of the polarized style and the style of analysis on the measurement sensitivity of beat-length. This is done by using magneto-optic modulation techniques in which the magnetic gap and magnetic intensity are known. In a commonly used style, the input light is linearly polarized and parallel to the birefringence axis of the fiber, and the two analyzing axes of Wollaston prism make 45° with the birefringence axis of the fiber. In addition to this style, two other experimental styles are found to provide high sensitivity. In one of these styles, the input light is linearly polarized having an angle of 45° with respect to the birefringence axis of the fiber, and the Wollaston prism is parallel to the birefringence axis. In the other style, the input light is circularly polarized and the Wollaston prism is parallel to the birefringence axis. The latter does not require accurate birefringence axis direction at the input end. This makes experiments more convenient and can reduce measurement error due to angle adjustment.

Solution to Broadcasting/Multicasting in Hybrid WDM/TDM PON

WANG Chong-yu;LIN Ru-jian;ZHU Min

2008, 14(6):  590-594 . 

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In this paper, a solution to broadcasting/multicasting in hybrid WDM/TDM PON using a broadcast wavelength channel is proposed. Simulation shows that the method can significantly reduce the burden of broadcasting/multicasting data processing in the unicasting channel and make effective use of wavelength resources in hybrid-PON systems. 

Sensor for Solution Concentration Based on Fused Tapering Optical Fiber Coupler

SHI Jie;CHEN Zhen-yi;PANG Fu-fei;WANG Ting-yun

2008, 14(6):  595-599 . 

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A new method for measuring concentration of solutions using a fused tapering coupler of optical fiber is reported. According to the shape-curve function of a fused tapering fiber and the super-mode coupling theory,relation between output coupling visibility (CV) of the coupler and refractive index of the medium surrounding the coupler is investigated. A 2×2 fused tapering single-mode optical fiber coupler is immersed into a solution in the experiment. When light is injected into the coupler, the CV is changed with variation of solution-concentration (refractive-index) surrounding the fused tapering zone of the couple. The solution-concentration sensor is realized. The theoretical and experimental results are in good agreement.

FEA Solution for Flows in Crash Impact

HOU Lei;HAN Yue-hong;QIU Lin;

2008, 14(6):  600-603 . 

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The process of the auto-crash test is expensive in labor, time and cost. The implicit finite element method solver MSC-Marc has been used for the sensitive triggering flow (secondary-mode) before the impact happens. The mathematical model of simulation is interesting for the passive safety in automotive protection devices. The Navier-Stokes equation is considered for a deformed moving boundary u condition and resulting cavity flowV problem in the impact perturbation.

Prediction of Protein-Protein Interactions in Term of Signal-to-Noise Ratio

FENG Tie-nan;JIANG Hao;WANG Yi-fei

2008, 14(6):  604-610 . 

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Protein-protein interactions play a critical role in the living body. In this work, the modified resonant recognition model is applied to predict interactions of the yeast proteins. Signal-to-noise ratio (SNR) is selected as a discriminant parameter. Comparing with the previously used peak value, SNR can show significant differences between the positive data and the random data more clearly without compromising prediction precision. Therefore, the proposed method can solve the over-fitting problem.

Bounds of Fault-Tolerant Locating-Dominating Sets

LI Ming-song;SHAN Er-fang;GAO Ming-jing

2008, 14(6):  611-616 . 

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Given a graph G=(V, E), any nonempty subset S of V is called a locating-dominating set if the sets I(v)=N［v］∩S are nonempty and pairwise different for all v∈V-S, where N［v］ is the closed neighborhood of v. A locating-dominating set S is called a faulttolerant locating-dominating set of G if it can locate a faulty processor for any w∈V when all processors in S transmit the correct value 0, 1, or 2 and when exactly one device incorrectly transmits 0 rather than 1 or 2.This paper studies the fault-tolerant locating-dominating set. We present bounds of the minimum cardinality of the fault-tolerant locating-dominating set, both in finite graphs and in infinite triangular grids.

Simulation of Energy Collection Wind Turbine Suitable for Arbitrary Wind Directions

CAO Zi-yin;HUANG Dian-gui;CAI Rui-zhong

2008, 14(6):  617-621 . 

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As fossil energy reserves decrease ceaselessly, many efforts have been made to find new substitutes. Wind energy, a type of clean, non-pollutive and renewable energy, is becoming increasingly important. In this paper, efficiency of the vertical axis turbine is investigated, which is suitable for arbitrary wind directions in collection-shield pattern. Flow field simulation indicates that this new kind of wind turbine can effectively raise the rotor output.

Property Analysis for LongLife Pavement Based on the Theory of Orthogonality

XU Di;XU Zhi-hong;ZHANG Dong-sheng

2008, 14(6):  622-628 . 

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To deal with the problem of early damages on road surfaces, appropriate design methods to ensure long life asphalt pavement are of great significance. Mechanical properties of the materials and structural thickness of the pavement play important roles in pavement structure design. In this paper, a test scheme is proposed to effectively reduce the cost of test based on the theory of orthogonality. By changing the structure control parameters, their influence on long life pavement design have been analyzed. Numerical results show that the proposed method can be used in long life asphalt pavement design and construction. 

Design of Simulation Experiment for Jet Track of Fire Monitor 
Based on Similarity Theory

WAN Feng;CHEN Xiao-yang;MIN Yong-lin;WANG Wei-min

2008, 14(6):  629-632 . 

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Currently, real fire monitors are used in almost all experiments for jet track of fire monitors. These experiments require large areas, bulky equipment, and complicated operations leading to high cost. We propose simulation experiments for the jet track, and derive the similar proportion based on the similarity theory. The method has the advantages of small space requirement, low cost, and data collection capability. The method has practical value as it can provide experimental data for studying properties of the fire engine and used for engineering design. Furthermore, the analysis model is a theoretical basis of the fire monitor database.

Topology and Control Strategy of a Novel Standalone Photovoltaic System

XIAO Peng;CHEN Guo-cheng;WU Chun-hua;ZHANG Yi

2008, 14(6):  633-636 . 

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Topology of a novel standalone photovoltaic system is proposed, which uses a push-pull output circuit. The system consists of a photovoltaic battery array, a charger, a battery and an inverter. The inverter is used for boosting and inversion so that a DC-DC boost circuit is omitted. The system can supply stable 220 V AC-voltage with a simplified main circuit. Besides, a modulation method based on HF-link SPWM and a control strategy for external voltage RMS loop and instant voltage internal loop is adopted. In this way, size and cost of the device are reduced, and excellent output voltage dynamic response and high steady state output accuracy are achived.

A New Method for Tracking Maximum Power for PMSM Wind Generation


LI Jie;WANG De-li;CHEN Guo-cheng;QU Ke-qing

2008, 14(6):  637-641 . 

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This paper introduces a simple and practical topology for PMSM wind generation and analyzes relationship between variety of duty cycle of IGBT element in a DC/DC link and one of generator speed. A new method for adjusting variety of the duty cycle for maximum power point tracking is tested. The process of maximum power tracking is analyzed with a sample chart. Experimental results show validity of the analysis. 

Effect of Thickness on Copper Phthalocyanine Film Prepared with Vacuum Evaporation

ZHANG Yu;SHI Wei-min;ZHENG Yao-ming;WANG Lin-jun;ZHU Wen-qing;XIA Yi-ben

2008, 14(6):  642-645 . 

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Copper phthalocyanine (CuPc) is an important versatile organic material, attracting increasingly more attention because of its unusual stability and photoelectric properties. Copper phthalocyanine (CuPc) films, grown by vacuum sublimation, were characterized with X-ray diffraction (XRD), Raman and ultra-violet visible spectrometry. Copper phthalocyanine (CuPc)/Aluminum (Al) Schottky solar cells were also studied by changing the thickness of the CuPc layer.

Release Welding Residual Stress in Anchorage Area Using Ultrasonic Impact

LIU Xiao-yu;YAO Wen-juan

2008, 14(6):  646-651 . 

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To solve problems in anchor plate of long-span cable-stayed bridge such as dense welds, thick connecting plates, and high and unknown distribution of welding residual stress, three full-scale ratio models are proposed. These are applied to cable-beam connection of anchorage area of Chongqing Jiangjin Guanyinyan Yangtze River Bridge. Welding residual stress was tested, and ultrasonic impact imposed on welds of the models. Ultrasonic impact can make weld toe as the center of a certain region producing sufficient deep surface of plastic deformation. It effectively improves welds and baseplates exterior shape of the transitional zone, and reduces stress concentration in the welds. Test results show that there is significant welding residual stress in the anchorage areas of tensile anchor plates, and ltrasonic impact can effectively reduce, even release, welding residual stress and improve the status of stress of welds. Ultrasonic impact can make the stress distribution in the welds more uniform, ensuring safety of the cable beam connection of anchorage area. In conclusion, ultrasonic impact is an effe
ctive method for solving the welding residual stress problem.

RP-HPLC Fingerprint for Quality Assessment of Ganoderma lucidum

GU Zhong-yan;WENG Xin-chu

2008, 14(6):  652-655 . 

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To establish an RP-HPLC fingerprint analysis for quality control of Ganoderma lucidum, HPLC fingerprint analysis method of Ganoderma lucidum was developed. ZORBAX Eclipse XDB-C18 (4.6 mm×250 mm, 5-Micon) was used, with mixture of acetonitrile and water solution of acetic acid as mobile phase in a gradient mode. The flow rate was 0.8 mL/min. The wavelength used in the measurement was 242 nm. Ten batches of Ganoderma lucidum were determined. The HPLC fingerprint chromatograms of different producing area were analyzed. The samples’ quality was assessed by Similarity Evaluation System for Chromatographic Fingerprint of TCM 2004. The method can be used to identify and evaluate the quality of Ganoderma lucidum conveniently.

Expression of Human Defensin HNP4 in Pichia Pastoris GS115

ZHAO Ting-ting;CAO Cheng-hua

2008, 14(6):  656-660 . 

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In order to construct a recombinant plasmid pPIC9K-HNP4 between vector pPIC9K and human defensin HNP4 gene and express active human defensin HNP4, HNP4 gene was amplified with PCR from plasmid pUC18-HNP4, which contains HNP4 sequence and is inserted into the yeast expression vector pPIC9K. The recombinant plasmid was lined fragment by SacI and transformed into Pichia pastoris strains GS115 yeast using electroporation. Transformant of human defensin HNP4 and Pichia pastoris was obtained using G418 to screen positive clone and PCR to identify integration of gene of HNP4 into genome of Pichia pastoris. The yeast transformant was induced by methanol to express human defensin HNP4. The results show that gene of human defensin HNP4 has been integrated into genome of Pichia pastoris with restriction analysis, and PCR identified. The expression of human defensin HNP4 was induced by methanol. An expected 4.0 kDa protein band appeared on SDS-PAGE gel and Western-blotting. The expression level of HNP4 protein in this strain was about 500 mg/L. The expressed raw product exhibited antimicrobial activity. This reveals that recombinant plasmid pPIC9K-HNP4 has been successfully constructed and expressed stably and efficiently in Pichia pastoris.