Table of Content

31 May 2005, Volume 23 Issue 3

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Articles

An Efficient Blind Channel Estimation Algorithm for MIMO-OFDM Systems

HOU Yong-min, RONG Meng-tian

2005, 23(3):  221-224. 

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The MIMO-OFDM technique is considered as one of the promising techniques in the future wireless system.In this paper, a new MIMO-OFDM channel model that has robustness to cope with channel order overestimation is proposed.Next a subspace based blind channel estimation algorithm for the new model is also presented.Simulation results show that the new algorithm has a faster convergence rate and better estimation performance.

A Wide-Band CDMA Receiver of Adaptive Antenna Arrays Combined with Interference Cancellation

YAN Yong-qing, ZHAO Chun-ming, YOU Xiao-hu

2005, 23(3):  225-229. 

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A wide-band CDMA receiver combined with adaptive antenna arrays and partial parallel interference cancellation (PPIC) is proposed.An novel pilot aided spatial-temporal receiver architecture for wide-band CDMA reverse links is proposed in the first stage to separate the signals in space.An improved parallel interference cancellation is employed for further reduction of residual multiple access interference (MAI) especially for in-beam MAI.Simulation results show that the performance of the receiver proposed is superior to the traditional adaptive antenna arrays or PPIC used alone in time variant Rayleigh fading channels.

Constructing Method of Proxy Blind Signature Scheme and Its Extension

ZHAO Ze-mao, LIU Feng-yu

2005, 23(3):  230-234. 

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A new proxy blind signature scheme is proposed.Based on this, all possible parameters to be chosen in signature equations are considered and a general method to construct proxy blind signature based on ElGamal's signature is obtained.From the view of computational complexity, the comparisons between these schemes show which one is better than others.The security of these schemes is also discussed and shown that they have good properties as unforgeability, distinguish-ability, non-repudiation and revocability etc.

The Structural Characteristics and Uniform Property of Bluetooth Channel Hopping Frequency Sequences

ZHANG Shen-ru, NING Zhong-hua, DENG Xiao-yan

2005, 23(3):  235-239. 

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In this paper, the structural character of Bluetooth channel hopping frequency sequences is analyzed.The uniformity of the sequences is theoretically proved in a length of time far shorter than a period of sequence.The clock condition of uniform distribution is given.The frequency stay of Bluetooth channel 79-hop sequence can appear only in some special clocks.Frequency stay probabilities of every code for 23 -hop sequence codes are (9/16×16).

Joint Speech Decoding Based on Channel Soft-Value and Bayes Estimation

ZHOU Lin, WU Zhen-yang

2005, 23(3):  240-244. 

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A joint speech-decoding algorithm is proposed in this paper.Based on the soft-value of channel decoder and the redundancy of source parameter, a posterior probability is calculated and used to estimate speech parameter according to MAP/MS criteria.Next the optimal parameter from the estimation model is decoded.Simulation carried our in accordance with G.711 and GSM EFR speech coding standard shows that the joint decoding algorithm obviously improves the SNR of decoded speech.

An Iterative Multi-user Detection Algorithm for Frequency-Selective Fast Rayleigh-Fading Channels

PENG Yue-xing, WU Zhen-yang, WANG Wei-xin, LIU Chen

2005, 23(3):  245-250. 

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The multiaccess interference (MAI) and frequency-selective fast-fading of the channels do great harm to credible communication and greatly decrease the capacity of broadband wireless mobile communication systems under the working environment of high-speed vehicle holding.In this paper, a modified partial parallel interference cancellation (PPIC) method is proposed to combat MAI for the uplink of DS CDMA systems, and a new channel model and its corresponding channel tracing method are also proposed for frequency-selective fast-fading channels.An iterative multi-user detection algorithm for the uplink of DS CDMA systems over frequency-selective fast-fading channels is realized through the information exchange between the MPPIC and channel tracking.The simulation results validate the proposed algorithm.

The Design of a New Band-Pass Sigma-Delta Modulator

CHENG Jian-ping, WEI Tong-li

2005, 23(3):  251-256. 

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Recently the Sigma-Delta modulator has been widely used in communication.One of the applications is to digitize the signal at intermediate frequency in a super-heterodyne receiver with a band-pass Sigma-Delta modulator.A band-pass Sigma-Delta modulator with a bandwidth at 1.25 MHz and a center frequency 20 MHz is designed, and a new modulator structure and its coefficient computing method are proposed.This structure is insensitive to coefficients variation, and its resonators' swing is low, thus lowering the requirement in the design of the operational amplifier.Simulation results indicate that the peak signalnoise-distortion-ratio of the modulator is 60 dB, and its dynamic range is 62 dB.

Nonlinear Controller Design Based on Developed Integrator Forwarding

CHEN Yi-mei, HAN Zheng-zhi

2005, 23(3):  257-260. 

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Integrator forwarding is a recursive nonlinear design technique for feed-forward systems.By this method, the stable control law and the control Lyapunov function of the original system can be obtained.In this paper, a developed design method is proposed in view of the limitation of the classical integrator forwarding design, hence effectively extends the field of the forwarding control.An example is provided to illustrate the effectiveness of the proposed method.

The Fabrication of Large Size CNT-FED Emitters

WANG Qi-long, LEI Wei, ZHANG Xiao-bing, WANG Bao-ping, ZHOU Xue-dong, ZHANG Yu-ning

2005, 23(3):  261-264. 

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Two fabricating methods of CNT emitters in large size FED are studied.Those are the spraying and the screnn-printing.Purification and disperse of CNT preparation of CNT paste, process of spraying and screen-printing are also introduced.With the simulations, the SEM graphics and the measurement results of field emission and both types of CNT emitters are analysed.The screen printing is more suitable for fabrication of emitters in large size CNT-FED.The post-processing technique of screen printing CNT emitters is also shown in this paper.

Secondary Electron Emission from Surface of Novel Gate Structure in CNT-FED

WANG Qi-long, LEI Wei, ZHANG Xiao-bing, DI Yun-song, ZHOU Xue-dong, LIU Min

2005, 23(3):  265-268. 

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In this paper, a new gate structure, a metal mesh with cone funnels is proposed.MgO film and MgF₂ film are deposited on the surfaces of the mesh and the funnels by evaporation.When the primary electrons bombard on the gate electrode with initial energy, the secondary electrons and backscatters are generated.The brightness of the novel triode structure CNT-FED increases.Simulation of secondary electron emission is done with Monte-Carlo.CNT-FED devices with the new type of gate structure are fabricated.The results of emission experiments are also shown in this paper.

CVAAS Adaptive Dynamic Power Management Policy

BU Ai-guo, HU Chen, LIU Hao, LI Jie

2005, 23(3):  269-273. 

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Dynamic power management (DPM) is an important technique to reduce power consumption in embedded and portable systems.DPM policies are online problems in nature which must be adaptive to the changes of system working surroundings.In this paper,A novel CVAAS adaptive technique for TimeOut policy based on the characteristics of the battery is presented.The experimental results show that CVAAS has strong stability, capable of guaranteeing the performance of the system and extending the battery lifetime.

A New High-Speed and High-Resolution Sample-and-Hold Circuit

CHEN Hong-wei, WU Jian-hui

2005, 23(3):  274-277. 

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A new sample-and-hold circuit based on an operational amplifier is described in this paper.It is useful to solve the conflict between speed and DC gain of an amplifier in a high-speed and high-resolution sample-and-hold circuit by using a speed compensation circuit.The circuit was simulated by 0.35 μm CMOS technology.The sample rate is higher than 70 MHz per second and the resolution is 10 bits.

The Effect of White-Pint Setting and Contrast on Perceived Sharpness

LIU Lu, XIA Jun, YIN Han-chun

2005, 23(3):  278-281. 

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In the market of display products, apart from technical performance and cost, the front-of-screen performance is considered as one of the main factors to satisfy the consumers.The front-of-screen performance depends not only on technical performance but also on visually perceived image quality.Thus visual perception study has assumed importance in recent years.In this paper, the effect of white-point setting and contrast on perceived sharpness was investigated through an experiment in which subjects were asked to evaluate the different images.The results were used in statistical analysis and compared with that from Philips research. This indicates that perceived sharpness has a relation with the displayed image.The white-point setting does not affect perceived sharpness.Chinese prefer a higher contrast setting, whereas European recognige the deterioration in sharpness due to higher contrast value.

A Method of Image Registration for Two Rotated and Translated Images

LI Zhong-ke, YANG Xiao-hui, WU Le-nan

2005, 23(3):  282-286. 

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In this paper, the problem of ambiguity in Onishi-Suzuki algorithm is analyzed in theory.Hough transform and phase correlation are combined to modify this algorithm.Based on 1D phase correlation, a method is proposed to obtain two candidates of the angle of rotation by searching an angle ridge.After derotation in terms of the above-mentioned candidates, the traditional 2D phase correlation is imported to get two translation candidates.Finally the true rotation angle and translation are obtained by decision.The method can take full advantage of the high efficiency of FFT.Experiments show that the proposed method can detect the rotation and translation between images efficiently and exactly.

A Structurally Dynamic and Static Collaborative Optimization Design under Distributed Circumstances

XUE Cai-jun, NIE Hong, QIU Qing-ying

2005, 23(3):  287-291. 

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Engineering application of the collaborative optimization technology is studied through an example-the design optimization of the working device of a hydraulic excavator.The technology route of structurally static and dynamic collaborative optimization is studied, and some useful strategies are put forward to deal with technology difficulties during the parameterized FEA modeling stage, the collaborative optimization modeling stage and the collaborative optimization stage.Based on the distributed collaborative optimization strategy and structurally dynamic and static collaborative analysis strategy, the design optimization process is completed automatically under Internet circumstances, and a satisfactory optimization result is obtained.

An Online Data Cleaning Method

HAN Jing-yu, HU Kong-fa, XU Li-zhen, DONG Yi-sheng

2005, 23(3):  292-296. 

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A new method for online data cleaning is presented.First, each clean record in the reference table is mapped as a point in a high-dimensional metric space measured by Manhattan distance.Next, all the points in the space are partitioned by clustering and indexed with B+ tree.In this way, the search in highdimensional space can be translated into search in one-dimensional space.To find the KNN (K nearest neighbors) in reference table for each incoming record, the search method of branch and bound is employed. The top K records that best match the incoming record are then identified.Theory and experiment show that it is an effective approach for online data cleaning.

The Distributed Metadata Management of Parallel File Systems with High Availability

LI Sheng-li, TANG Wei, SHI Ke, CHENG Bin, MENG Ting-you

2005, 23(3):  297-299. 

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Metadata management is one of the key techniques for building a parallel file system.This paper presents a metadata management mechanism for a parallel file system named HANDY, which attains high availability of metadata and dynamic scalability of metadata servers.

Optimization of ETL Execution by the Horizontal Partitioning Method

HAN Jing-yu, XU Li-zhen, DONG Yi-sheng

2005, 23(3):  300-304. 

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ETL is a tool suite for data loading and maintaining of data warehouse.How to efficiently shorten the ETL process execution time is a big challenge because the volume of data to be processed is very large. Four types of view horizontal patition approaches such as " single fact derived by one view", " single fact derived by many views", "many facts derived by one view" and "many facts derived by many views" are proposed to shorten the execution time.The theory and experiment result prove it to be efficient.

The Construction of Refinable Function Based on Convolution

XIE Chang-zhen

2005, 23(3):  305-307. 

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Let φ₁, φ₂ be two refinable functions with the dilation factor a.A new method for constructing the refinable function based on the convolution of functions φ₁, φ₂ is presented.The properties such as periodicity and symmetry of the refinable function generated by the convolution of functioins φ₁, φ₂ are discussed.The B-spline function N_{i +j}(x) can be constracted by the convolution (N_i *N_j) (x) of two B-spline functions N_i(x) and N_j(x).Finally, two examples are given to illustrate how to use the method to construct refinable function.

Basic Functions in MoM for Solving 2D EM Scattering Problems

ZHAO Liu, ZHU Feng

2005, 23(3):  308-310. 

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According to the symmetric feature of a scattering cylinder whose cross section is square, classified basis functions can be obtained by means of the group theory.This paper shows a new way to obtain the basic functions used in MoM for solving EM sacttering problems with complicated symmetric boundaris.

Photons and Weak Gravitational Field

PAN Peng-peng, LU Hui-qing, HUANG Zeng-guang

2005, 23(3):  311-314. 

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Using the fundamentals of geometrical optics' method to study the interaction between the static field and the photon, the speed of photon in gravitational field is obtained and then the deflection of light and radar echo delay in Reissner-Nordström (R-N) field is discussed.General relativity is verified with a new approach.This method is novel and brief, and it is suitable to other fields.The study of the geometrical optics and metric optics about light propagation in plasma is very hot recently, in principle our new method can also be used in this field.

An Asymptotic Analysis of an Infection-Age-Dependent SIR Epidemic Model with Nonlinear Infectivity

XU Wen-xiong, ZHANG Su-xia

2005, 23(3):  315-318. 

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The dynamical behavior of an infection-age-dependent SIR epidemic model with nonlinear infectivity is studied and the threshold, a basic reproductive number which determines the outcome of the infectious disease, is found.When the basic reproductive number is less than or equal to 1, there exists only the disease-free equilibrium.Moreover, when the basic reproductive number is less than 1, the disease-free equilibrium is globally asymptotically stable and the disease will die out, whereas, when the basic reproductive number is greater than 1, there exist both the disease-free equilibrium which is unstable and the endemic equilibrium which is locally asymptotically stable, and the disease will persist.The paper concludes with the relevant results of the corresponding ODE models.

The Electromagnetic Model and Parameters Optimization of the Novel Cylinder Linear Driving Motor Used in Mobile Sculpture

ZHAO Ji-wen, KONG Fan-rang, LIU Wei-lai, LI Xiao-feng, WANG Jian-ping

2005, 23(3):  319-323. 

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Based on the analysis of the structure of the traditional cylinder-type linear motor, a novel cylinder linear motor is designed to solve the drive problem of mobile sculpture.By analyzing the special features of the structure of the motor, the axisymmetric FEM model is set up.The parameters of pushing force and currents are obtained through the results of simulation.Furthermore, by using the simulation results as sample data, structure parameter optimization is carried out through the orthogonal test.And the model of linear motor is made according to the optimum results.The test results of the model linear motor show that the method suggested in this paper is feasible for researching a new kind of linear motion actuator.

A Study on the Error Estimation of INS Installed on Submarines

LIU Wei-ren, ZHUANG Liang-jie

2005, 23(3):  324-326. 

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In order to ensure the output precision of long-time-working INS(inertial navigation system), it is necessary to reset the INS to ensure the safety of submarines.A simply but efficient scheme has been designed according to the characteristics of submarines underwater navigation.The analysis and simulation results show that this scheme can estimate the velocity errors of INS efficiently.Finally, the feasibility of this scheme is also analyzed.

Research Notes

Research and Development on Controlling System of Speed Measuring Platform in Hefei Science and Technology Museum

YIN Zhi-qiang, LI Fu-jun, JIANG Huai-wei, ZHU Wei-guo

2005, 23(3):  327-330. 

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A linear speed measuring system, which has phonetic and animated output equipment, has been developed.The system's controlling CPU is a AT89C55 microcomputer, and it adopts quick reaction infrared photo triode as the input signal.The phonetic chip ISD1420 has been carefully researched, and the chip's working mode and basic circuit diagram are both described in the paper.Based on the study of SED1335 liquid crystal display device, the interface circuit between AT89C55 and SED1335 are introduced.