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November 30,2011
Volume 4,Issue 22
Pages -
Subject Area:Communications Technology

Title: Research on the blind detection and parameter estimation for OFDM signals in multi-path Rayleigh fading channels

Authors: YUAN Zelin, ZHANG Wenhui, HU Qianlin
PP: 2100-2104
Abstract: This paper presented an algorithm for blind detection and parameter estimation of orthogonal frequency division multiplexing (OFDM) signals based on cyclic prefix which was suitable for multi-path Rayleigh fading channels. It used the sum of correlation coefficients of many OFDM symbols which could be against multi-path interference efficiently. The simulation experiment proved that it was a simple algorithm with much higher recognition accuracy.
Keywords: signals detection; parameter estimation; cyclic prefix; multi-path Rayleigh fading channel

Title: Analysis on discharge characteristics of intrinsically safe capacitive circuits by index model

Authors: ZHANG Yao, DING Enjie, SHI Yanyan, XI Jinjin
PP: 2094-2099
Abstract: This paper analyzes discharge characteristic of capacitive intrinsically safe circuits based on discharge waves gained by International Electrotechnical Commission (IEC) spark apparatus tests, builds discharge voltage index model of capacitive circuits. It analyzes discharge time, discharge power and discharge energy from the model, and simulates the model by Matlab. The simulation results are compared with the actual discharge characteristics, and verified to describe the energy and power transmission of intrinsically safe circuits, for analyzing the security of intrinsically safe circuits qualitatively.
Keywords: electronic technology; intrinsically safe; discharge characteristic of capacitive circuits; discharge model

Title: A novel 40 Gb/s OFDMA-PON architecture which supports dynamic bandwidth allocation

Authors: ZHAO Bo, CHEN Xue
PP: 2089-2093
Abstract: The paper has proposed a novel orthogonal frequency division multiple access-passive optical network (OFDMA-PON) architecture that can reach 40 Gb/s over 20Km SSMF. The system uses Mach-Zehnder modulator (MZM) to transform electrical signals into optical signals. Single side-band filter is used to filter out half of the signal, thereby the influence of the dispersion is reduces, the receiver easily restores the signal. Direct detection technology is used at the receiver to reduce the cost and to meet the cost requirement of PON system. The system supports dynamic bandwidth allocation, different subcarriers can be allocated to different optical network units (ONUs), and the number of subcarriers allocated to each ONU can be differently according to the amount of tasks running on the ONU, the way of bandwidth allocation is very flexible. Through building the simulation model and simulation validation, it is concluded that under the condition of BER less than 10e-3 the receiver’s sensitivity can reach to -20 dBm.
Keywords: fibre optical communication technology; passive optical network; orthogonal frequency division multiple access; direct-detection; dynamic bandwidth allocation; 40 Gb/s

Title: Stationarity test of signal via surrogates

Authors: JI Guanqun, LI Ming
PP: 2082-2088
Abstract: The method of surrogate data realizes the stationarity test via comparing characteristics of original data and surrogate in time-frequency distribution which represent their stationarity and also comparing original data with its surrogates in time-frequency domain to determine whether it is stationary or not. The experiment indicates that the method can test stationarity of signal well in given observation scale.
Keywords: communications technology; stationarity test; random signal; surrogate; time-frequency distribution; change-point; observation scale

Title: Design and simulation of microstrip fractal array antenna for MIMO system

Authors: DU Qingliang, LIU Jianxia
PP: 2076-2081
Abstract: Second-order square iteration microstrip fractal array antenna and first order Koch microstrip fractal array antenna are designed in this paper. Using HFSS 10.0 to simulate and optimize antenna models, so that the two microstrip fractal array antennae are suitable for 4.20 GHz/5.80 GHz bands and 4.75 GHz/5.80 GHz bands, respectively. It can be seen that the two array antennae’s gain is significantly improved, cross-polarization isolation and the port isolation are greater than 15 dB, and both achieve circular polarization. The two microstrip fractal array antennae meet the small size, multi-band, circularly polarized, reasonable gain, and low-related design requirements for the multiple input multiple output (MIMO) system to provide a certain reference value.
Keywords: microware technology; microstrip array antenna; multiple input multiple output system; fractal antenna; circular polarization

Title: Recognition of text image from electromagnetic leakage of computer

Authors: ZHANG Shen, ZHANG Hongxin, LV Yinghua
PP: 2072-2075
Abstract: Based on the interception of electromagnetic (EM) leakage arising from computer, the intercepted text image is obtained by using filtering, synchronization, phase locked technology. Then, the noises are suppressed through the smoothing method with the mean value of the neighbor pixels of the image, and the preprocessing is done through the binarization processing and image segmentation. Further, the feature extraction is executed based on the statistic probability of the image pixels, and the classification and recognition of the text image are completed. At last, the software for the recognition of text image is developed using Bayesian classification algorithm based on statistic probability method, and the text image from the EM leakage of computer is recovered and reconstructed. From the examine result of the recovered text image in statistics, it shows that the recognition accuracy is high.
Keywords: electromagnetic field and microwave technology; information leakage; Bayesian algorithm; image recognition; information reconstruction

Title: Research on nonlinear filter based on RBF neural network

Authors: CHEN Meiling, JI Changpeng
PP: 2068-2071
Abstract: Digital filter has many problems such as can not calculate weighting coefficients of filter in real time and can not achieve real-time nonlinear filtering. In order to solve these problems, a nonlinear filtering method which utilizes local approximation properties of radial basis function (RBF) is proposed in this paper, and is applied to nonlinear filtering. Through Matlab network design and error analysis, it is concluded that the application of RBF to nonlinear filtering is feasible and has a better result. The method can make up the processing defect of linear filter when dealing with the nonlinear interference and improve previous filtering technology.
Keywords: signal and information processing; digital filter; radial basis function; non-linear filter; signal processing

Title: Chinese accent identification based on multi-layered features with gender-dependent model

Authors: HOU Jue, LIU Yi
PP: 2061-2067
Abstract: This paper proposes a novel two-stage approach for Chinese accent identification using multi-layered features with gender-dependent model. A combination of conventional Mel frequency cepstrum coefficients (MFCC) parameters and pitch contour features as an example of segmental and suprasegmental features is exploited to capture the characteristics in Chinese accents. The cubic polynomials are used to estimate the pitch contour segments in order to model the differences within accents. A two-stage scheme is used to deal with the gender variation, by training gender-dependent Gaussian mixture model (GMM) acoustic models to express the features. Since conventional criterion of the GMM assumption cannot solve those multi-feature problems, the support vector machine (SVM) is used to make the decision. The effectiveness of the proposed approach is evaluated on the 863 Chinese accent corpus. The result shows that our approach yields a 20% relative error rate reduction compared to conventional approaches of using only MFCC features and without modeling gender.
Keywords: signal and information processing; Chinese accent identification; support vector machine; multi-layered features; gender-dependent model

Title: Parameters optimization and application of changed SVM based on PSO

Authors: WANG Jie, BAI Jing, LIU Xiaofeng
PP: 2055-2060
Abstract: The standard support vector machine (SVM) is a common method of machine learning, and the parameters selection of SVM affects the machine learning ability directly, but present researches do not have uniform method. For avoiding the difficult problem of selecting parameters, this paper uses the changed SVM which is v-SVM, and selects parameters of v-SVM based on particle swarm optimization (PSO), and applies the optimized parameters in the speech recognition system. The results of the experiment show that the method is effective and feasible, and the optimized parameters make v-SVM have good generalization. Comparing with the general method the recognition results have improved.
Keywords: signal and information processing; v-support vector machine; particle swarm optimization; speech recognition

Title: Calculation of conversion efficiency of InGaN-based heterostructure solar cells

Authors: LIU Bin, WANG Rui, HU Hainan, ZHANG Rong, XIE Zili, CHEN Dunjun, LI Yecao, WEN Bo, JIANG Ruolian, HAN Ping, ZHENG Youdou
PP: 2049-2054
Abstract: In this paper, based on the current-voltage equation for p-n junction solar cells, the conversion efficiency (CE) of single-tandem and double-tandem InGaN as well as double-junction heterostructure InGaN-based solar cells (SCs) has been calculated. It is found that with In composition x~0.77 and band gap of InxGa1-xN Eg ~ 1.33 eV, the CE of single-junction SCs achieves up to 31.9%. The CE of four type double-tandem heterostructure InGaN-based SCs, including InGaN/GaP, InGaN/GaAs, InGaN/Si, InGaN/Ge, are calculated. The results indicate that In0.73Ga0.27N/Ge heterostructure double-tandem SC has the optimized band gap match~1.54 eV/0.66 eV to solar spectrum, whose CE can reach up to 46.7%, which is experimental feasibility.
Keywords: microelectronics and solid state electronics; conversion efficiency of solar cells; current-voltage equation; Ⅲ-nitride semiconductors

Title: Design and hardware implement of automatic white balance based on chromaticity difference

Authors: XU Jiangtao, SU Xiaohui
PP: 2044-2048
Abstract: In this paper an automatic white balance algorithm is proposed, in which color temperature statistical point is chosen based on the chromaticity difference to effectively remove large area color piece interference. CIE 1976 Lab chromaticity difference formula is used in the comparison of neighborhood pixels’ chromaticity difference. The pixels inside a color piece are statistically filtered to get the more accurate color temperature information. By the demand of accuracy, piece wire approximation method is used. Constant coefficient multiplier is used in the calculation of Lab chromaticity difference. To save hardware cost, the edge detection operator calculation is replaced by the checking of chromaticity difference with threshold. The field programmable gate array (FPGA) simulation indicates that, 4 720 logic cells and 6 144 bits memory are used in processing a 640 columns×480 rows picture. The result shows that, the chromaticity difference based inside pixels removing method can effectively avoid color temperature interference.
Keywords: microelectronics and solid state electronics; automatic white balance; color temperature statistics; chromaticity difference; Lab color space

Title: Influence of annealing on I-V characteristic of ZnO nanorods/n+-Si heterojunction

Authors: HUANG Huihui, FANG Guojia, LI Songzhan, LONG Hao, MO Xiaoming, WANG Haoning, ZHAO Xingzhong
PP: 2041-2043
Abstract: In this paper, the ZnO nanorods/n+-Si heterojunction was fabricated by growing vertical and compact ZnO nanorods on heavily doped n type silicon wafer using a low-temperature aqueous solution method. The influences of different annealing time under 630℃ on the I-V characteristic of the ZnO nanorods/n+-Si heterojunction were studied, and the experimental results revealed that the rectification behaviours of the I-V curves were greatly enhanced by increasing the annealing time, and the reason was studied in this work.
Keywords: mirco electronics and solid state electronics; ZnO nanorods; heterojunction; I-V characteristics; annealing

Title: Research on hierarchical sliding mode control method of TORA system

Authors: BAO Yuqing, XIE Jihua, GAO Bingtuan
PP: 2035-2040
Abstract: Two different hierarchical sliding mode controllers are designed for an underactuated translational oscillator with rotational actuator (TORA) system. Firstly, the TORA system is separated into two subsystems according to the degrees of freedom. Each subsystem contains two state variables, which are chosen to construct a sub-sliding surface. And the total sliding surface is defined as a function of the two sub-sliding surfaces. For the two methods of hierarchical sliding mode control, the first method is to define the total sliding surface as a piecewise linear function of the two sub-sliding surfaces. With this method, the stability of each sub-system can be guaranteed theoretically. The second method is to define the total sliding surface as a continuous linear function of the two sub-sliding surfaces. However, the coefficient sign of the continuous linear function should be determined by analyzing the model. Finally, simulation results demonstrate the feasibility of the two controllers. Moreover, simulation results of the controlled system with the second method have better performance than those with the first method.
Keywords: robot control; underactuated; translational oscillator with rotational actuator; sliding mode control

Title: Active visual method for mobile robots localization

Authors: LI Baoquan, FANG Yongchun, ZHANG Xuebo, HE Wanfeng
PP: 2029-2034
Abstract: For a monocular camera-based mobile robot system, the paper proposes an active visual method for robot localization. It first obtains world frame coordinates of image feature points and the landmark using a 3D reconstruction method, which obtains the environment information. Then, a nonlinear pan-tilt camera controller is designed for the purpose of making the landmark in horizon center of image, which realizes repeated observation of the landmark. On this basis, the visual measurement algorithm is designed to acquire the robot location. The performance of the active visual localization method is validated by the experiment results, showing that a higher accuracy of localization can be reached by realizing repeated observation of the landmark.
Keywords: robot control; mobile robots; active visual; visual localization; landmark

Title: Force distribution optimization and simulation of mobile robot in rough terrain

Authors: HE Long, XU He, WU Yongjian
PP: 2022-2028
Abstract: The force control method not only can avoid the robot’s slippage, but also can result the robot in good mobility and trafficability. This paper presents a rough-terrain control method, which based on the three-dimensional rough terrain. Through the simulation, the results clearly express the force distribution of robot’s each wheel, and make a theoretical analysis for the torque control of mobile robots.
Keywords: robot control; mobile robot; force optimization; simulation; rough terrain

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