Table of Content

20 April 2003 Volume 30 Issue 2

  

Original Articles

Performance study of target recognition methods based on the 1D HRR profile

PEI Bing-nan1;2;BAO Zheng1;CHEN Jian-feng2

J4. 2003, 30(2):  141-145. 

Abstract ( 2163 )   Save

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The mathematical model of HRR profiles is first given, adn then the classification performance of the existing methods such as the Baseline method, Correlation method, Bispectrum method, Principal Eigenvector method, and Quardratic Classification method is analzed by teh distance discriminant criterion, from the phase of the averaged HRR profile(AHHRP) and the covariance matrix(COVM) of the profiles. The above methods are divided into two categories: linear classifiers based on AHHRP, and quadratic classifiers based on both AHHRP and COVM. The obtained result shows that the quadratic classifier has better performance in classification than the linear one because it uses the information in COVM of profiles besides AHHRP.

Narrow-band interference suppression in DSSS by thresholding of the subband transform

SHI Guang-ming;LI Fu-dong;JIAO Li-cheng;LIU Fang

J4. 2003, 30(2):  146-150. 

Abstract ( 1781 )   Save

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We address the problem of suppressing a narrow-band interference(NBI) in direct-sequence spread spectrum(DSSS) communications with the subband transform. The signal and NBI are transformed into the subband domain with orthogonal filter bands. A subband threshold method is proposed for the suppression of NBI. The simulation results show that the performance of suppressing NBI by the propoed method is not lower than that by methods available, adn the proposed method needs less time to process signals than other methods.

A novel method for estimating DOA in the presnece of unknown colored noise fields

CHEN Jian-feng1;WU Yun-tao1;ZHANG Xian-da2

J4. 2003, 30(2):  151-154. 

Abstract ( 2111 )   Save

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a new method for estimating spatial narrow-band signal directions of arrival in the presence of colored noise with unknown covariance is presented. A transform-based covariance differencing approach is given, thus overcoming the highly biased estimates. Without the eigendecomposition of the transformed data matrix, its advantage consists in a computational complexity reduced by the ratio of the number of sources to teh number of sensors. Finally, its performance is confirmed by computer simulations.

Keystone transformation based ISAR imaging at the low SNR level

CHEN Wen-chi;BAO Zheng;XING Meng-dao

J4. 2003, 30(2):  155-159. 

Abstract ( 2309 )   Save

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In the process of the ISAR data with a low input SNR when the target is flying smoothly, the conventional motion compensation method is no longer valid. In this paper, a new motion compensation method based on the Keystone transformation is proposed for dealing with the data with a low input SNR. The Keystone transformation is used to eliminate the effects of linear range alignment caused by the radial velocity of the target. By coherently accumulating the adjacent range profiles, the SNR is increased so that the envelope correlation and PGA algorithms can be applied to compensate the high order radial motion. The simulation results show that, for the process of the data with a low input SNR, the performance of the method proposed in this paper is better than that of the classical method, so that it is possible to increase the radar range at which targets can be imaged.

A block-matching algorithm based on hardware implementation and its VLSI architecture

ZHAO Bo;DU Jian-chao;YAN Yao-ping

J4. 2003, 30(2):  160-164. 

Abstract ( 1690 )   Save

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Based on the cost of hardware implementation and the precision of estimation, a new block-matching algorithm named the Hierarchical Quasi-Full Search Algorithm(HQFSA) is proposed. HQFSA can be easily realized by hardware. A parallel architecture as well as a pipelining architecture is proposed based on one-dimentional array processor with sequential inputs and processing with 100 percent efficiency. The HQFSA combines the main idea in the full search algorithm with that in the hierarchical block matching algorithm. The hardware cost of HQFSA is a quarter that of the full search algorithm. The clock frequency is reduced as a result of the parallel architecture. The experimental results show that the PSNR of HQFSA is comparable to that of the full search algorithm and better than that of the hierarchical block matching algorithm and other fast matching algorithms. We have also proposed an data memory scheme for reducing the cost based on the recommendation H.263. We have already realized this algorithm using FPGA.

Forward kinematics of a general Stewart parallel manipulator using the genetic algorithm

ZHENG Chun-hong;JIAO Li-cheng

J4. 2003, 30(2):  165-168. 

Abstract ( 1613 )   Save

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By making full use of the property that it is easy to obtain the inverse kinematics of the Stewart parallel manipulator, the forward kinematics of the Stewart parallel manipulator is transformed into an optimal problem, and a real coded genetic-based forward kinematics method for the general Stewart parallel manipulator is proposed in this paper. The feasibility of the genetic based forward kinematics method is illustrated with the Stewart fine tuning platform for he next generation large radio telescopes. The high accuracy of the forward kinematics is obtained, which has overcome the shortcoming that the accuracy of the forward kinematics is susceptible to the initial guess values with the conventional numerical methods.

Dynamic behavior of discrete Hopfield neural networks with delay

Ma Run-nian1;3;LEI She-ping2;ZHENG Lian-qing3;XU Jin1

J4. 2003, 30(2):  169-173. 

Abstract ( 1486 )   Save

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The dynamic behavior of discrete Hopfield neural networks with delay is studied. The conditions that the networks with delay are convergent to a limit cycle of length 1 or 2 are given. Also, the conditions that the networks with delay are convergent to a limit cycle of length 2 are achieved. Furthermore, the obtained results are validated by giving examples. These results here provide a theoretical foundation for further analysis and new applications of the discrete Hopfield neural networks with delay.

A new algorithm for motion estimation and tracking based on line correspondence

CHU Xiu-qin;LI Yu-shan;YANG Li

J4. 2003, 30(2):  174-178. 

Abstract ( 1697 )   Save

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The relationships of line parameters between the states before and after planar motion of a rigid body are first deduced. A new algorithm based on the line correspondence for estimating motion parameter is proposed, which can be used to estimate the object's revolving parameters in addition to the object's translating parameters. For the conventional point correspondence algorithm, it is hard to work out all of them at the same time. Furthermore the iterative formula for automatic moving object tracking is presented as well. The homogeneous coordinate is adopted to facilitate the complex coordinate system transfer plus motion synthesis along the tracking process. The simulating experiments show that the quite accurate results under the high noisy environment can be acquired by this algorithm.

Target recognition based on kernel Fisher discriminant

LI Ying;JIAO Li-cheng

J4. 2003, 30(2):  179-182. 

Abstract ( 1706 )   Save

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The recognition of the actual ship noises based on the kernel Fisher discriminant analysis is investigated. The main idea of this method is to find a nonlinear direction by first mapping the data nonlinearly into some feature space and compute Fisher's linear discriminant there, thus implicitly yielding a nonlinear discriminant in input space. The mechanism of the kernel Fihser discriminant analysis is particularly analyzed and the classification algorithm is developed. The recognition results are encouraging. In addition, this method is compared with other state-of-the-art classification techniques. Experiment shows that the kernel Fisher discriminant(plus a linear support vector machine to estimate the threshold) is superior to other algorithms.

A modified LMP algorithm for an adaptive impulsive noise canceller

ZHANG Li;FENG Da-zheng

J4. 2003, 30(2):  183-185. 

Abstract ( 1447 )   Save

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For the cancellation of impulsive noise in the desired signal, a modulated LMP algorithm is applied. According to the estimate of input signals, this algorithm is modified on the basis of the LMP algorithm. A new measure for signal distortion in impulsive noise, namely fractional order signal-to-noise ration(FSNR), is introduced to quantify the performance of the impulsive noise cancellation algorithm. The LMP algorithm and the modified algorithm are compared in performance in seven different input SNRs. In comparison with LMP algorithm, the MLMP algorithm is more stable and its convergence is faster. Results show that the performance of the modified algorithm is obviously superior to that of the LMP algorithm.

Embedded zeroblock coding with optimized truncation

DING Gui-guang;GUO Bao-long;CHEN Long-tan

J4. 2003, 30(2):  186-190. 

Abstract ( 1249 )   Save

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With the broad application of the image coding algorithms to engineering, the researches on the memory-constrained image coding algorithms have been paid more and more attention to. In this paper, an embedded image coding algorithm based on zeroblock, called Embedded ZeroBlock coding with Optimized runcation(EZBOT), is presented. It operates the set-partition based on zeroblock, in which the independence between the zeroblocks ensures that the algorithm is effective under the memory-constrained condition. In order to improve the quality of the reconstructed image, we introduce an optimized truncation scheme to allocate the number of every sub-bitstream's bits. In this scheme, there is more than one truncation point available in every zeroblock, at which the value of the rate-distortion function can be computed. So, given the compression ratio, we can select the approximate optimized truncation point for every zeroblock according to the slope of the rate-distortion function at each truncation point. The experimental result shows that EZBOT is very effective under the memory-constrained condition.

Analysis of the generalized channel of the wireless OFDM system and blind adaptive channel estimation algorithm for the OFDM system

LI Feng;LI Jian-dong;LI Xia

J4. 2003, 30(2):  191-196. 

Abstract ( 2069 )   Save

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A theoretic analysis is made of the generalized channel of a wireless OFDM system, in which the FFT of the OFDM receiver is considered as a part of the generalized channel. It is proved that the output of the subchannel of the wireless OFDM system generalized channel and its nonlinear estimation are subject to the Bussgang procedure. Thus, a blind adaptive algorithm, LMS-Bussgang, is proposed for blind channel estimation. Meanwhile, a novel amelioration scheme is presented for accelerating the convergence of the algorithm and preventing error propagation, thus avoiding the degradation of efficient transmission rate and transmission delay due to periodical retransmission of pilot signal in systems with coherent detection. Both theoretic derivation and simulation results show that the algorithm is robust, less complex, and suboptimal.

Crosstalk analysis of the OXC topologies with multicasting capability

HU Liao-lin;LIU Zeng-ji

J4. 2003, 30(2):  197-200. 

Abstract ( 1518 )   Save

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The crosstalk of two OXC topologies with multicasting capability is analyzed. Then the output power equation for the topologies are derived in the worst case. According to the equations, the total crosstalk as a function of the number of wavelengths and the number of input/output fibers is studied. From the comparison we can find that the crosstalk of the two topologies performs almost equally for multicast connections and the crosstalk of teh OXC based on MOSaD is lower than that of the OXC based on SaD for unicast connections. In the condition of state-of-art technologies, when the number of wavelengths equals 4 and the number of input/output fibers equals 2, the crosstalk is as much as -17dB in the case of multicasting.

Application of discrete WVD to teh digital demodulation for FSK signal

FENG Xiao-ping;ZHAO Huan-jun;ZHANG Lin

J4. 2003, 30(2):  201-204. 

Abstract ( 1418 )   Save

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This paper presents a new digital demodulation method for the FSK signal, based on the Wigner-ville Transform. The FSK signal is discussed in the time-frequency plane, and the statistical methods are used to evaluate its frequency and code element width. A typical example about demodulation of 8FSK is given, and the effect of different windows is discussed. Finally the simulative results of this demodulation method under different signal-to-noise ratios(SNR) are presented and compared with the STFT demodulator.

Resource management scheme in IPLS networks based on service differentiation

YAN Jiang-zhou;LIU Zeng-ji

J4. 2003, 30(2):  205-209. 

Abstract ( 1648 )   Save

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Traditional IP networks, which cannot support real-time services such as voice and video sufficiently, cannot keep up with the rapid growth of Internet services. However, IPLS(IP Packet Label Switching) technology, based on the switching labeled IP packet in the network, can provide QoS guarantee to user traffic through classification, marking and admission control at edge nodes. Based on service differentiation, a resource management scheme in IPLS networks is presented. An implementation of the scheme using the self-similar traffic model is given.

Research on deriving the document type definition of XML from frame

SHI Jun;CHANG Yi-lin

J4. 2003, 30(2):  210-214. 

Abstract ( 1279 )   Save

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This paper presents an approach to adding true semantic to extensible markup language(XML) documents. Frame is the appropriate medium between the information and the XML document. The frame is mapped to the XML document to integrate conceptual modeling, inheritance and inference mechanism with popularity, simplicity and flexibility of XML. By deriving the Document Type Definition from a frame, XML is more semantic expressive and by this way, it becomes easy to share and exchange data.

Threshold-based dynamic playout algorithm and choice of its parameters for continuous streams

XU Yan;CHANG Yi-lin;LIU Zeng-ji

J4. 2003, 30(2):  215-219. 

Abstract ( 1515 )   Save

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A dynamic playout algorithm is proposed in order to keep multimedia playing smoothly, which deals with the problem from the perspective of an end system. In the algorithm playout rates of multimedia are variable according to the occupied buffer level with an intention of eliminating buffer underflow or overflow. The playout rates are chosen based on the requirement of the intra-media synchronization. To determine the thresholds of the occupied burrfer level, a queuing model is established. Based on the analytical results, suitable thresholds can be determined according to the system parameters, including the probability of buffer underflow, the probability of buffer overflow, the verage playout rate and the average occupied buffer level.

Formal specification of the Bimodal Multicast in IOA

GUO Jin-lin;LIU Xi-yang;CHEN Ping

J4. 2003, 30(2):  220-225. 

Abstract ( 1501 )   Save

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The character of the bimodal multicast is introduced with an example. Formal specification of the bimodal multicast is discussed. A formal specification of bimodal multicast based on IOA is presented, mainly including the definition of the action and state space of the bimodal multicast and the description of the message. The description of the random semantic is also discussed, with emphasis on the "most recent first" os the bimodal multicast.

An analysis of the switching delays of the different adaptation schemes in VC merging

CHEN Peng;YOU Hua;LIU Zeng-ji

J4. 2003, 30(2):  226-229. 

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An analytical comparison of switching delays of AAL3/4 and AAL5 in VC merging for MPLS is presented. Based on the switching model with output buffers, an explicit expression of mean switching delay is given, and the relation between the merging factor(the proportion of the cells involved in VC merging) and the mean switching delay is discussed. Finally the result is verified by simulation using MATLAB. The analysis result indicates that, in VC merging, without the waiting requirement of gathering all cells belongings to a packet due to possession of MID field in the PDU format, the cells of AAL3/4 have a smaller mean dealy and the lower buffer demand than those of AAL5.

The generation of correlated rayleigh fading channels by mixture

WANG Chao1;TAO Xiao-yan2;WU Shun-jun1

J4. 2003, 30(2):  230-232. 

Abstract ( 1392 )   Save

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By mixing two weighted independent white Gaussian random sequences, a pair of demanded correlated white Gaussian random sequences, the orginal and the new mixed sequences, can be generated to meet the occasions of correlated Rayleigh fading channels in wireless communication and radar systems. Furthermore, correlated channels with other pdf can also be generated by this means. Finally the validity of the method is proved by simulation result.

QoS control and performance of the IP-based universal terrestrial radio access network

XU Zhan-qi;LIU Huan-feng;LIU Zeng-ji

J4. 2003, 30(2):  233-238. 

Abstract ( 1495 )   Save

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As the third generation mobile system(3G) migrates to the all-IP based network, the IP Quality of Service(QoS) plays a significant role in 3G. This paper discusses the QoS control, Differenated Services, and implementation in the IP-based Universal Terrestrial Radio Access Network(UTRAN), with emphasis on the user service models and principles of the QoS simulation in UTRAN. A analysis of the simulation results and some conclusions are presented.

Full anonymity converting multi-certificate electronic auction

ZHANG Jian-hong;WU Qian-hong;WANG Yu-min

J4. 2003, 30(2):  239-242. 

Abstract ( 1361 )   Save

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Anonymity is a vital properly of sealed-bid. A security electronic auction should satisfy the following properties: (1)equity, (2)security of bid, (3)anonymity and (4)validity of the bidder's bid. In this paper, we propose a full anonymous and convertible multi-certificate electronic auction in the case of protecting the winning bidder. It can resist rigging-bid by multi-certificate and protect the real identity of the winner by crypt-sign and verify bid's validity of the winner by the undeniable converting signature. It is full anonymity in the whole auction and no one can manipulate the other bidders.

Workspace analysis of fine tuning Stewart platform for large radio telescope

SU Yu-xin1;WEI Qiang2;DUAN Bao-yan1

J4. 2003, 30(2):  243-246. 

Abstract ( 1461 )   Save

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The workspace of the robot is the base for the mechanical synthesis and trajectory tracking. In the light of the characteristics of five-freedom, the polar coordinate searching method is used to determine the workspace of the fine tuning Stwewart platform for the large radio telescope. The effectiveness of the method is illustrated by an example. The result has laid a solid base for the feed trajectory tracking and the design of the fine tuning Stwewart platform for the large radio telescope.

Analysis of the mutual coupling effects between the base station antenas by MoM

CHEN Sheng-bing;JIAO Yong-chang;ZHANG Fu-shun;LIU Qi-zhong

J4. 2003, 30(2):  247-250. 

Abstract ( 1572 )   Save

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The mutual coupling effects between the base-station(BS) antennas are analyzed accurately using MoM in this paper. The analysis model of the mutual coupling between antenna is given. The mutual coupling effects between BS diversity antennas in the horizontal spaced diversity antenna system are discussed. The mutual coupling effects between the BS antenna operating at different frequencies are also analyzed according to several typical installation conditions. Some useful conclusions are also drawn from the viewpoint of mutual coupling between antennas.

Study on the optimal placements of the actuator in the shape precision control intelligent structures of the mesh shape antenna reflector

LIU Ming-zhi;LIU Jun

J4. 2003, 30(2):  251-254. 

Abstract ( 1380 )   Save

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The shape precision control of the large diameter and high precision mesh shape antenna reflector in the orbit has become one of the major developing trends of modern space techniques. In this paper, a new way for the optimal placements of the actuator in the shape precision control intelligent structures of the mesh shape antenna reflector with the characteristics of large size and flexiblility is used: mode analysis technology is applied to optimize placements of the actuator. The modal importance factor is defined, and then by weighting the candidate active members strain energy in each mode by the corresponding modal importance factors, the criterion TC of optimal placements of the acturator is obtained. The results of simulation shows that the control method is very effective.

Measurement of doping concentration in strained Si_1-xGe_x with four-probe array

DAI Xian-ying1;WANG Wei1;ZHANG He-ming1;HE Lin2;ZHANG Jing2;HU Hui-yong1;Lü Yi1

J4. 2003, 30(2):  255-258. 

Abstract ( 1643 )   Save

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Based on a new majority carrier mobility model of the strained Si_1-xGe_x material, the relation between resistivity and doping concentrations with different Ge compositions has been obtained. With this relation, the doping concentration in strained Si_1-xGe_x can be measured by using a collinear four-probe array. The characterization technique is compatible with the on-line measure of the doping concentration in Si but much simpler and more convenient.

Methods for solving invariants and state equations for Petri nets

LI Zhi-wu;WANG An-rong;JIA Jian-yuan

J4. 2003, 30(2):  259-263. 

Abstract ( 1802 )   Save

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Invariants and state equations play an important role in Petri net analysis. New methods for solving the invariants and state equations of Petri Nets are developed in this paper. Also, the general solutions of the firing vector in the state equation of a Petri net are proposed. And all of these approaches are derived from the full rank decomposition technique for the incidence matrix. Finally, the esistence condition for the integral solution of state equations is discussed, which, as a matter of fact, is a necessary condition for reachability and is significant for the analysis of Petri nets.

Case-based reasoning for the calculation of the relational degree in a fualty diagnosis system

WANG Dong;LIU Huai-liang;XU Guo-hua

J4. 2003, 30(2):  264-266. 

Abstract ( 1487 )   Save

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Case-based reasoning is applied to a faulty diagnose system. The method of building the faulty cased base and result base is discussed, and these bases are restored according to database. A method for the definition and calculation of teh relational degree based on the grey-relational theory and fuzzy-set theory is put forword so that similar cases can be found out accurately. A fundation is laid for future research.

Grafted genetic algorithm for the job-shop scheduling problem

WANG Shu-zhen1;XU Dian2

J4. 2003, 30(2):  267-270. 

Abstract ( 1967 )   Save

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Standard Genetic Algorithm has limitations of low convergence rate and premature convergence in solving job-shop scheduling problem, and some improved algorithms available only solve one of those limitations. To it, this paper presented a Grafted Genetic Algorithm(GGA) inspried by graftage in botany. The improved algorithm accelerates convergence rate greatly and also increases the ability to fight premature by introducing grafted population and crossover probability matrix. Finally, the algorithm was test-proved, and it shows the superiority in terms of stability, convergence and precision.

Nonharmonic wavelet basis and approximation function with time-frequency localization

SHI Zhi1;2;SONG Guo-xiang1

J4. 2003, 30(2):  271-276. 

Abstract ( 1343 )   Save

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Wavelets are functions generated by translating and dilating a function or a finite number of functions. In this paper, we consider that the orthonormal basis (ψ_m,n )_m,n∈Z for L²(R) is replaced by the nonharmonic wavelet basis ψ_m,λm=2^-m/2 ψ(2^-m x-λ_n), m,n∈Z, (|λ_n-n|≤1 such that f∈L²(R) has nonharmonic wavelet expression f(x)=∑_m,n c_m,nψ_m,λm·(ψ_m,n )_m,n∈Z is used to approximate function f which is "essentially localized" in time-frequency. The result in Dauberchies is developed.

Multivalued rough set based attribute reduction algorithm

WANG Jue;LIU San-yang;ZHANG Jie;LIU Zhen-hua

J4. 2003, 30(2):  277-280. 

Abstract ( 1305 )   Save

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The significance of attributes in the information system is defined from the viewpoint of the information theory. Then a new reduction algorithm based on a novel definition of entropy is developed. Simulation results show that the algorithm can find the minimal reduction in most cases.

Study of nonlinearity bounds of Boolean functions

ZHENG Lian-qing1;ZHANG Chuan-rong1;2;DONG Qing-kuan2;FU Xiao-tong2;XIAO Guo-zhen2

J4. 2003, 30(2):  281-283. 

Abstract ( 2024 )   Save

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The previous results about nonlinearity bounds of Boolean functions are compared and analyzed completely. For that, some problems which need research are pointed out. Especially, the nonlinearity bounds of functions with balancedness, with correlation-immunity, or with balanced correlation-immunity are discussed respectively. Using the relationship between nonlinearity and the order of correlation-immune, one upper bound of nonlinearity of correlation-immune functions is obtained.

Quantum fluctuations in the damped capacitive coupled electric circuit with resistance in the coupling part

LIANG Mai-lin;YUAN Bing

J4. 2003, 30(2):  284-288. 

Abstract ( 1374 )   Save

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According to the physical mechanism of teh generation of the resistance or the collisions of electrons with the phonons, the capacitive couple4d electric circuit is quantized when there exists resistance in the coupling part. Effects of the resistance in the coupling part on the quantum fluctuations are given. At the same time, the thermo effect is considered. Results show that the coupling capacitance can reduce the quantum fluctuations of the electric charge in the component circuits and the coupling part.