Table of Content

30 November 2005, Volume 23 Issue 6

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Articles

Face Recognition Based on KPCA and Optimal Discriminant Independent Components

HE Yun-hui, ZHAO Li, ZOU Cai-rong

2005, 23(6):  551-556. 

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Independent component analysis (ICA) is a generalization of principle component analysis (PCA), which encounters some problems in face recognition.These problems are analyzed and three approaches proposed to improve the performance of ICA-based face recognition.First, a kernel based ICA method with KPCA is presented, which maps samples onto the feature space and obtains nonlinear independent components.Second, Fisher discriminant information is defined to select optimal discriminant independent components.Finally, a method is proposed to obtain the optimal feature representation using optimal discriminant independent components for unknown face samples.Experiments using ORL database indicate that the improved method outperforms FLDA, with recognition stability better than FLDA in case the number of features is small.

A Hop Generation Method for FH Signals Interception System Based on Spectrogram

FAN Wei, XU Pei-xia, DAI Xu-chu

2005, 23(6):  557-562. 

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The paper presents a hop generation method for a frequency hopping (FH) signals interception system based on spectrogram.The hop generation performance of the proposed method is investigated, and the iterative SAHADTA algorithm that calculates the average contribution of a single actual hop to dwell-time histogram developed.A numeric example is also given.Theoretic analysis and the example show that the proposed method has good hop generation performance even under low signal detecting probability, making the hop-based clustering more reliable.

OBS Burst Assembly Algorithm with Safety Space and Universal Parameters

LI Lei, ZHANG Xing, ZHANG Ming-de, SUN Xiao-han

2005, 23(6):  563-567. 

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A novel burst assembly algorithm with safety space is proposed for optical burst switching in edge routers.Moreover, a concept of unit input bit rate is introduced to improve universality.Based on this algorithm and self-similar traffic, the assembly process is simulated.Influences on burst creation, burst length distribution, packet loss ratio, total output data, and valid information ratio are discussed by setting appropriate parameter values including ultimate burst lengths, assembly time threshold, etc.

Turbo MMSE Linear Equalization for Multi-level Modulations

LI Jing, PENG Hua, GE Lin-dong

2005, 23(6):  568-572. 

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A turbo equalizer is able to overcome severe inter-symbol-interferences because it benefits from the channel decoding gain by iteratively performing equalization and channel decoding.One of the key problems involved in turbo equalization is the information transmission between the equalizer and the decoder.In this paper, a linear minimum mean square error (MMSE) equalizer for turbo equalization of multi-level modulations is discussed.Simplified computation of the equalizer's extrinsic information for 16 QAM modulation is presented.The extrinsic information of the decoder is also discussed, and a new extrinsic information feedingback scheme proposed.Simulation results show that the proposed algorithm works effectively for multi-level modulations over severe frequency selective channel.

High-Rate Single-Carrier Space-Time Block Coding for Frequency-Selective Fading Channels

YANG Lu-xi, QIAN Yi-qun, YANG Bing

2005, 23(6):  573-576. 

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For broadband wireless communication systems with 4 transmitting antennas, a two-stream multiplexed space-time block-coding scheme is proposed.Each stream employs two transmitting antennas and adopts full-rate orthogonal space-time block coding.The proposed coding scheme achieves a code rate of 2 and requires the channels to be stationary over only two consecutive blocks.Two antennas are needed at the receiver to separate the two space-time block coded streams.Interference cancellation and frequency-domain equalization at the receiver have low complexity while offering full transmission diversity gain for both streams.

Capacity Regions of Wireless Piconet-Based ad hoc Networks

ZHAI Xu-ping, BI Guang-guo, XU Ping-ping

2005, 23(6):  577-581. 

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Based on the IEEE 802.15.3 high-rate WPAN Standard, a system model for wireless piconet-based ad hoc network is proposed, and the capacity region is defined.An approach to computing the capacity region is described.Effects of transmission power, discrete power control, discrete transmission rate and multihop routing on the capacity region are studied.The results show that both increase of transmission power and adoption of multihop routing can significantly expand the capacity region.The discretized transmission rate significantly reduces the network capacity, while the multi-level power control has little impact on the capacity regions.These provide important theoretical guidelines for the design of cross-piconet communication, routing protocol and power control algorithm in wireless piconet-based ad hoc networks.

A Metric of ad hoc Networks Reliability: Degree of Network Balance

YU Xu-tao, ZHANG Zai-chen, BI Guang-guo

2005, 23(6):  582-585. 

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Ad hoc networks are multi-hop wireless networks without fixed infrastructure.Reliability is a fundamental consideration.A measure of network balance is defined by node importance to evaluate the reliability of networks.Analysis and simulation results show that this measure reflects the performance of networks and can effectively evaluate the network reliability.

Instantaneous Polarization Recognition of Ballistic Missile Targets

LI Yong-zhen, WANG Xue-song, LI Jin-liang, XIAO Shun-ping, ZHUANG Zhao-wen

2005, 23(6):  586-590. 

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The problem of feature-extraction and recognition of ballistic missile targets is studied.Based on the instantaneous polarization scattering matrix of radar targets, descriptions of its electromagnetic scattering characteristics are presented using the matrix theory.The first and second order polarization measures of radar targets are then derived with measured data of warhead targets, which are insensitive to the pose of radar targets.Classification and identification of missile targets are studied through nearest neighbor recognition methods.

High-Speed High-Resolution Comparator for Design of ADC

WU Guang-lin, WU Jian-hui, YANG Jun, RAO Jin, LUO Chun

2005, 23(6):  591-594. 

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In this paper, various offset-canceling techniques in comparators are reviewed, and high-speed high-resolution comparator design techniques and a new offset canceling technique are then described.The comparator includes three preamplifiers, an output latch and offset canceling circuit.Experimental results show that, after offset adjusting of the comparator, an offset error of about 56.8 μV is achieved, and it is able to resolve 0.1 mv at a comparison rate of 100 MHz under the condition of a single +3.3 supply using Chartered 0.35 μm CMOS technology.

A High Linearity Current -Steering CMOS IF VGA

YUN Ting-hua, TANG Shou-long, LUO Lan

2005, 23(6):  595-599. 

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A current-steering IF VGA based on an analog multiplier is designed.A nonlinear model is established and analyzed based on the MOSFET I-V model in strong inversion, and a linearity optimization method is presented.Simulation results based on 0.25 μm CMOS technology indicate that about a 33 dB decrease in the third order inter-modulation at maximum input and a 12 dB increase in gain control range of the optimized VGA with 3.3 V supply voltage are obtained.The ⅡP3 at the minimum gain setting is 17.5 dBm, and the minimum NF is 7.8 dB.

Design of a Configurable Circuit for Bluetooth

HE Ji-rou, YI Xiao-feng, WANG Fang-lin, HONG Zhi-liang

2005, 23(6):  600-603. 

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In the design of such RF integrated circuits as Bluetooth, switched capacitor arrays is used and both the output power of a power amplifier (PA) and the center frequency of a frequency synthesizer must be adjustable.They need some kind of digital control.In this paper, a configurable architecture for Bluetooth is presented, in which various analog parameters can be set freely.The core circuit is described in detail, which is smartly designed and takes very few pins.The tested result shows that all the analog parameters can be set properly, ensuring the functions and performance of RF building blocks in Bluetooth.

A DC Model of High-Voltage VDMOST for SPICE Simulation

ZHAO Ye, SUN Wei-feng, YI Yang-bo, BAO Jia-ming

2005, 23(6):  604-609. 

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An accurate model for high-voltage hexagon VDMOST is derived based on a three-dimensional structure and implemented with SPICE.Drift region resistance, buried layer resistance, interior node voltage and variation of internal capacitance with external applied voltage are analyzed in detailed.A DC equivalent circuit model is also proposed, which includes a level 3 NMOS transistor, a controlled source and capacitance, etc.It also accounts for the quasi-saturation effect in high voltage device.This simple model with a clear physical concept also provides easy extraction of inter-electrode capacitances.The I-V simulation results are in good agreement with experimented results with the DC error approaching 5%within the entire voltage range, which can be used in practical applications.

Visual Perceived Sharpness in Image Display

LIU Lu, YIN Han-chun, XIA Jun

2005, 23(6):  610-614. 

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With development of display technology, not only the technical performance and cost, but also the perceived image quality has become important aspects of consideration by consumers.Visibility in sharpness differences is investigated in this paper in two experiments in which sharpness of different still images with different blurring levels is assessed by different people.Statistical analysis is made.The results show that text images are clearly more critical for judging sharpness than natural color images.In terms of the diagonal step response, the visibility threshold of sharpness differences is equal to an angular resolution of 14 arcsec for natural color images and 5 arcsec for text images.

An Improved Classification Algorithm Based on Multiple Class-Association Rules

ZHAO Chuan-shen, SUN Zhi-hui

2005, 23(6):  615-619. 

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Classification is an important aspect in data mining research.In this paper, a new associative classification algorithm, fast classification based on multiple association rules (FCMAR), is proposed.This algorithm removes items that do not generate frequent rules so that storage space is saved and efficiency improved.Experimental results show that the FCMAR algorithm is efficient and effective.

Fault Diagnosis and Fault-Tolerance Control for Nonlinear Systems with Linear Output Structure

WANG Hong, SHEN Ling, YUE Hong

2005, 23(6):  620-624. 

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A new formulation of fault diagnosis and fault-tolerant control algorithm is presented for a class of nonlinear dynamic systems with a linear output structure.A Lyapunov-based adaptive observer is proposed to produce a residual signal.The fault estimate guarantees negativity of the first order derivative of the Lyapunov function using Lyapunov analysis.Two adaptive observers are designed for fault-tolerant control, and the system output after occurrence of a fault tracks the output of the original system through a nonlinear controller reconfiguration.Simulation results show the effectiveness of the proposed algorithm.

Basic Formulation and Uniqueness of Solution to the Inverse Problem of Schrödinger Equation

LIU Wei-xia

2005, 23(6):  625-630. 

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In this paper, a multidimensional elastic wave equation is reduced to the Schrödinger equation. Basic formulation of the inverse problem of Schrödinger equation is described, and proof of uniqueness of its solution is given.

Modeling Instantaneous Milling Force Based on Analysis of Machining Errors of Thin-Walled Parts

WU Kai, HE Ning, LIAO Wen-he, HE Lei

2005, 23(6):  631-634. 

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Researches on machining errors of thin-walled parts are reviewed.The importance and specific requirements of the cutting force model in the errors analysis are presented and emphasized.Based on the existing publications, advantages and disadvantages of the models are commented, and some improvements proposed.Combined with cutting experiments, the cutting force models in different cutting zones are built. Accuracy of the model is verified in experiments.

Factors Affecting Radial Internal Clearance of Operating High-Speed Rolling Bearing

ZHANG Yong, FEI Ye-tai, LIU Shan-lin

2005, 23(6):  635-639. 

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Radial internal clearance of high-speed rolling bearing in operation directly influences the performance and service life.It is affected by centrifugal force, fitting status and temperature, among which temperature is particularly important.Although the total effect is the sum of all factors, the current studies are mostly concentrated on individual factors without treating the system as a whole and taking into account relations between different effects.The mutual relations between centrifugal force, fitting, and operating temperature that influences the radial internal clearance of high-speed rolling bearing is discussed in this paper.This is of important significance for increasing the operation life and improving accuracy of operation.

Three Dimensional Reconstruction of Spatial Drone Position and Posture

WU Jia-qi, CHEN Jin-bo

2005, 23(6):  640-644. 

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This paper introduces a reconstruction method of spatial drone position and posture to meet the requirement of object tracking in an augment reality (AR) system.Based on the point and line reconstruction methods, the position relationship between the spatial vector and its projection onto any plane is analyzed. Methods for reconstruction of spatial vectors in the world coordinate system and the image coordinate system are derived and used in the 3D reconstruction of spatial drone position and posture.Verification of the technique is presented.

Safety Analysis of a Six-Legged Robot Moving on a Spherical Surface

TAN Shi-li, SU Jian-liang, SHEN Li-hong, WANG Yang-ming

2005, 23(6):  645-647. 

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This paper presents an analysis of a six-legged climbing robot moving on a spherical surface.Antisliding and anti-turning over conditions are obtained, which are helpful for both gait-planning of this robot and safety analysis of other multi-legged robots.

Prediction of Properties of (Zr_0.7Sn_0.3)TiO₄ Dielectric Ceramics Using Support Vector Regression

ZHAI Wen-hua, LU Wen-cong, LIU Xu, CHEN Nian-yi, WANG Guo-qing

2005, 23(6):  648-653. 

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The support vector regression (SVR) is applied to investigate the relationship between the properties and formulation of (Zr_0.7Sn_0.3) TiO₄ dielectric ceramic.The models for predicting dielectric constant and loss angle tangent are proposed respectively.Using the leave-one-out cross-validation method, the mean relative errors (MRE) of dielectric constant in SVR, back-propagation artificial neural network (BP-ANN) and multiple linear regression (MLR) models are checked, with the results of 1.083%, 1.632% and 1.931% respectively.Similarly, the MRE of loss angle tangent in SVR, BP-ANN and MLR are 0.999%, 1.746% and 1.414% respectively.It is therefore demonstrated that support vector regression is a useful tool in dealing with multi-variable problems with non-linearity or small size of data set in the formulation design of dielectric ceramics.

A Study on the Cointegration Forecast of Runoff

CHANG Ming-qi, LIU Jun-ping

2005, 23(6):  654-657. 

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A view of the nonstationary nature of runoff series, the cointegration theory is introduced into the analysis of runoff to establish reliable mathematical model.Taking the Yellow River as an example, through unit root testing and cointegration testing, the error correction model which can describe the cointegration relationship between the runoff of the upper and lower reaches is set up.In this way the initial cointegration forecasting model is set up.The results show that the forecasting model is feasible.

Research Notes

Research on Inlaid Algorithm of Image Digital Watermarking Based on Wavelet Set Decomposition Transform

FU Wei, XING Guang-zhong, HOU Lan-tian, JING Yuan

2005, 23(6):  658-660. 

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This paper presents a kind of improved algorithm of self-adaptive digital watermarking based on wavelet set decomposition.First, the algorithm pre-processes and makes the watermarking image into confusion, then it decomposes the host image into three layers with wavelet set transform.The authors present a kind of inlaid algorithm of self-adaptive digital watermarking based on Human Visual Sense (HVS) Property and Wavelet Set Group (WSG) in watermarking inlaid algorithm of the paper.The algorithm introduces HVS and multi-resolution ratio inlaid technique based on WSG so that better anti-offensive robustness property and visual sense effect are achieved.