Table of Content

20 June 2006 Volume 33 Issue 3

  

Original Articles

A time series model for accurately predicting the WLAN traffic

CHEN Chen;PEI Chang-xing;ZHU Chang-hua;CHEN-Nan;YI Yun-hui

J4. 2006, 33(3):  337-340. 

Abstract ( 1956 )   PDF (204KB) ( 930 )   Save

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During the process of studing much random selected real environmental WLAN traffic, the multiplicative seasonal
property of WLAN traffic has been discovered. By the use of differencing and specific sampling of the orginal data sequence,
the seasonal property is verified in this paper. A time series model is given which can accurately predict the WLAN traffic:
Multiplicative Seansonal ARIMA Model (0,1,1)(0,1,1)₁₂. After serveral iterative computations, the model is transformed into
an MA model and its parameters have been estimated using the character of the MA model. A prediction of the random selected
WLAN traffic has been finished by the differencing function. The result of the prediction shows that the proposed model can
short-term forecast the WLAN traffic and obtain a better result with an average relative error of only 0.0401 when the
forecast steps are 10.

Study of the minimum-energy path-preserving topology control algorithm for wireless Ad Hoc networks

SHEN Zhong;CHANG Yi-lin;CUI Can;ZHANG Xin

J4. 2006, 33(3):  341-346. 

Abstract ( 1774 )   PDF (252KB) ( 885 )   Save

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We propose a distributed topology control algorithm for constructing a wireless network topology with the
minimum-energy property, namely, it preserves a minimum-energy path between every pair of nodes. Moreover the proposed
algorithm can be used in both the homogenous and the heterogeneous wireless networks. Simulation results show that the
proposed algorithm has advantages over the topology control algorithm based on the direct-transmission region in terms of
average node degree and power efficiency.

PAPR reduction for COFDM with Golay coding scheme and system implementation

LI Wei-ying;Lü Zhuo;LI Jun-wei;CAI Feng

J4. 2006, 33(3):  347-351. 

Abstract ( 2218 )   PDF (216KB) ( 891 )   Save

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According to complementary sequence characteristics, we study the algorithm for PAPR reduction in OFDM systems
with Golay complementary sequences which are constructed by the Reed-Muller codes. In terms of the balance between complexity
and implementation, we propose a new decoding scheme, which makes selection in the cosets so as to reduce the complexity of
decoding and satisfy the real-time requirement. Finally, the simulation results in the AWGN channels show that the proposed
algorithm can constrain PAPR within 6 dB and achieves satisfactory BER performance.

Distributed adaptive routing algorithms in Torus networks

GU Hua-xi(1);LIU Zeng-ji(1);WANG Kun(2);XIE Qi-ming(1)

J4. 2006, 33(3):  352-358. 

Abstract ( 1589 )   PDF (258KB) ( 797 )   Save

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Based on the Turn Model, three distributed adaptive routing algorithms are proposed for Torus networks, which
split the physical network into virtual networks. According to the predefined rules, packets use different virtual networks
on their way to destinations. In 2D Torus networks, only three virtual channels are needed. This is the minimum number of
virtual channels to implement the adaptive routing algorithm in Torus networks. Simulations of the performance of three
algorithms under different configurations are done by OPNET software. The results show that, compared with the popular
dimension order routing algorithm, the three adaptive algorithm can achieve better performance under different traffic
patterns because of adaptiveness.

A new feedback control scheme for media synchronization

WU Wei(1);CHANG Yi-lin(1);LUO Zhong(2)

J4. 2006, 33(3):  359-365. 

Abstract ( 1616 )   PDF (221KB) ( 800 )   Save

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A new feedback control scheme for media synchronization is proposed. The playout buffer level is checked to
detect asynchronism. Once an asynchronism occurs, a required corrective transmission frame rate of the media stream is fed
back to the sender to compensate for delay jitter and network anomaly to restore intra-media synchronization. With
intra-media synchronization within a single media stream such as audio and video performed, the receiver synchronously
initiates to play them back, and then inter-media synchronization between audio and video is required. Experimental results
show that in the case of an unincreased playout delay the scheme could remarkably decrease the probability of lost media
unit. The scheme could keep continuous presentation of a single media stream, and require inter-media synchronization between
audio and video.

Joint subcarrier and power allocation algorithm for multiuser OFDM systems and its performance

LI Xiao-hui;LIU Nai-an;YI Ke-chu;GU Hua-xi;KOU Wei-dong

J4. 2006, 33(3):  366-370. 

Abstract ( 2551 )   PDF (198KB) ( 1044 )   Save

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Adaptive resource allocation is crucial to improving the spectrum efficiency for OFDM systems. A novel resource
allocation algorithm is developed here to assign subcarriers and power to each user. According to the users rate
requirement, the subcarriers are allocated with proportional fairness. The improved multiuser water-filling algorithm, with
the consideration of the bit error rate, is used to determine the power on each subcarrier. The results show that the
proposed algorithm can obtain a high spectrum efficiency and that the bit error rate and the fairness among the users are
considered simultaneously.

Research on the algorithm for channel estimation on the MIMO－OFDM system in fast-moving environment

FU Wei-hong(1);SHI Fan(1);YANG Xiao-niu(2);LIU Nai-an(1)

J4. 2006, 33(3):  371-375. 

Abstract ( 1927 )   PDF (200KB) ( 897 )   Save

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Based on the analysis of the Doppler effect of the mobile channel, the performance of two MIMO-OFDM systems
(STTC-OFDM and SFBC-OFDM) in the fast-moving environment is studied. Then, the algorithm for channel estimation based on the
training sequence is extended into the fast-moving environment by introducing the space-frequency coding, the method of the
equal-interval pectinate pilot-inserting, and the complete Maximum-Likelihood space-frequency decoding. According to the
simulation results, the capability of anti-Doppler-effect of these two systems is perfect in the case of 256 sub-carriers, 32
equal-interval-inserting pilots. These results also show that this algorithm can adapt to the fast-moving channels.

Running motion planning for the humanoid robot in the sagittal plane

WEI Hang-xin;LIU Ming-zhi

J4. 2006, 33(3):  376-380. 

Abstract ( 1351 )   PDF (212KB) ( 919 )   Save

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A new method based on the “virtual leg” is presented which can realize the running of the humanoid running
robot in the sagittal plane. Firstly, the trajectory of the center of mass (COM) of the robot is planned by solving the two
dimensional dynamic equation of “virtual leg” in the stance phase and the COM of the robot moves like a projectile in the
air in the flight phase. Then the trajectories of two feet and two arms are planned which are followed by the kinematic
parameters calculated by solving the nonlinear equations with the Newton-Raphson algorithm. Finally, the torque of each joint
is achieved according to the dynamic equations. The simulation results show that the angle of each articulation and the
torque of each joint change smoothly and that the stability margin is high. The running robot can run at the speed of 1.2m/s
in the horizontal direction.

A new model for analyzing security protocols formally

MU Jian-jun

J4. 2006, 33(3):  381-385. 

Abstract ( 1525 )   PDF (169KB) ( 776 )   Save

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Strand space is a new model for the formal analysis of security protocols. By using the theory of order relation,
a very important conclusion used to analyze security protocols formally with the help of the strand space model is shown. By
constructing penetrator strands for the Woo-Lam protocol we present a strand space model infiltrated for this protocol.
Moreover, with the help of this strand space model infiltrated we analyze the flaw in this protocol and illustrate that this
flaw in this protocol can be overcome in the improved Woo-Lam protocol. The strand space model discussed above is
distinguished from other models by its simplicity and can avoid the state space explosion problem.

Method for geometric distortion correction of missile-borne SAR

YU Gen-miao(1;2);DENG Hai-tao(2);WU Shun-jun(1)

J4. 2006, 33(3):  386-389. 

Abstract ( 1969 )   PDF (163KB) ( 930 )   Save

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This paper concerns the issue of image geometric correction of missile-borne side-looking SAR during its
descending flight. According to the missile flight features, the SAR operation geometric model is presented. Because of the
decrease of altitude during SAR operation, the SAR image is seriously distorted. In this paper, the geometric distortion
correction method for the SAR image obtained by the sub-aperture RD algorithm is proposed. The validity of the method is
demonstrated by simulation.

A contract-based interprocedural safety analysis method

YANG Xiao-qi;LIU Jian

J4. 2006, 33(3):  390-394. 

Abstract ( 1353 )   PDF (137KB) ( 785 )   Save

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A contract-based method for C and C++ interprocedural safety analysis is proposed. With bottom-up analysis, the
process of interprocedural analysis is made consistent with that of the intraprocedural analysis. By associating variables
and functions with contracts to record pre- and post- conditions, and updating the contracts according to the rules
constructed, safety checking can be done automatically during the program analysis. The method can be used to detect safety
holes, such as illegal pointer references, memory leaks, and other resource leaks, at a low cost and with high flexibility.

Study of the wideband phased array radar with transmitting null beamforming

CAO Yun-he(1);LI Qiang(1);WANG Sheng-hua(1);ZHANG Shou-hong(1)

J4. 2006, 33(3):  395-399. 

Abstract ( 2110 )   PDF (196KB) ( 935 )   Save

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In order to suppress wideband interference and make the pattern null in the direction of interference, a new
wideband transmitting beamforming algorithm is presented based on the LFM waveform. The method uses digital weight and
frequency-dependent phase weight to replace phase shifters at the element level and analog time delay units at the subarray
level respectively, which avoids using analog time delay units that cause quantization style errors and high cost. Moreover,
digital weight in subarray can be constructed by the narrowband method and make a wide null, realizing the wideband pattern
null finally. Finally, the computer simulations illustrate that the proposed algorithm can keep waveform range resolution and
obtain pattern null.

A DF method for the improved correlative interferometer

LI Chun(1);LIAO Gui-sheng(1);LI Yan-bin(2)

J4. 2006, 33(3):  400-403. 

Abstract ( 1633 )   PDF (177KB) ( 1771 )   Save

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A new estimation method, called the improved correlative interferometer, is presented for direction finding(DF).
Unlike the conventional correlative interferometer, which uses phase difference directly, it firstly employs trigonometric
functions of the measured phase difference to construct complex number vectors, and fits them to the array manifold which is
a continuum of response vectors of the antenna array. Since trigonometric functions are continuous at all points including
the boundary of the principal value region, this technique naturally solves the problem of the break of phase differences and
eliminates the data match error. Neither the unwrap of phase differences nor the data match among long baselines and short
ones is necessary, and thus the described approach is simple and robust. The results of numerial simulations and applied DF
systems show its validity and correctness.

Stability criterion for networked control systems based on the model of the time-delay system

ZHANG Xi-min(1;2);ZHOU Li-hua(2);CHE Xiang-quan(2)

J4. 2006, 33(3):  404-407. 

Abstract ( 1563 )   PDF (161KB) ( 950 )   Save

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The asymptotic stability time-delay criteria for the networked control systems are much conservative by solving
the linear matrix inequality or the linear quadratic Gaussian problem and they are of great computing complexity. In this
paper, an asymptotic stability time-delay criterion for the networked control systems is derived from the matrix norm
inequality and the newly constructed Lyapunov function by modeling the networked control systems as a time-delay system and a
laconic line search algorithm to determine the bound of the asymptotic stability time-delay is also presented. The example
and the comparison analysis with the corresponding criteria are provided to demonstrate the reduced conservatism of the
proposed condition.

A new algorithm for infrared mono-station passive location based on a mobile platform

LI En-ke(1;2);YIN Shi-min(1);LIU Shang-qian(1);FU Xiao-ning(1)

J4. 2006, 33(3):  408-410. 

Abstract ( 2432 )   PDF (119KB) ( 888 )   Save

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A new algorithm for infrared mono-station passive location for a mobile target is presented based on infrared
imaging, series images processing and three dimensional movement analysis. The algorithm results in the relative distance
between the maneuvering target and the measurement station by using the measured information of the infrared imaging target.
It is applicable to such relative motion models between the maneuvering target and the maneuvering measurement station as the
invariable velocity, invariable accleration and variable acceleration and so on with high location precision, small cubage
and great mobility. The correctness and validity of the algorithm are illustrated by both the computer digital simulation and
the semi-practicality visible light imaging simulation. The algorithm is also suitable for visible light imaging mono-station
passive location.

Combination of Turbo equalization and Turbo TCM with low-complexity

YANG Peng;GE Jian-hua

J4. 2006, 33(3):  411-415. 

Abstract ( 1414 )   PDF (198KB) ( 939 )   Save

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A novel low-complexity scheme of Turbo Trellis-coded Modulation(TCM) iterative equalization and decoding is
presented, which serially concatenates a soft-input-soft-output(SISO) equalizer and symbol-by-symbol Turbo TCM(TTCM) decoder
through an iterative process in order to realize iterative equalization and decoding process. This scheme can not only
improve the bandwidth efficiency, but also reduce the intersymbol interference (ISI). The equalizer with maximum a
posteriori(MAP) is replaced with a linear one based on the minimum mean-square error(MMSE) at the receiver so that the
complexity of the system can be reduced greatly. Computer simulation results show that the novel low-complexity receiver on
the fading channel can achieve comparable performance with TTCM on the Gaussian channel with coding.

An improved algorithm for moitoring the network fault

ZHANG Xin(1;2);CHANG Yi-lin(1);SUN Fang-tao(1);SHEN Zhong(1);JIANG Li(2)

J4. 2006, 33(3):  416-421. 

Abstract ( 1426 )   PDF (204KB) ( 721 )   Save

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Based on the hierarchical network architecture, we propose an improved dynamic monitoring algorithm for reducing
the management overhead. By analyzing the probability of the alarm occurrece with the sampled network information, the
proposed algorithm prolongs the interval between two consecutive pollings when no alarm could occur. This method
significantly reduces the amount of monitoring traffic and guarantee to detect the abnormal event. The simulation results
show that the proposed monitoring scheme reduces both the number of pollings and the cost of the network management, and
consequently improves the network performance.

An improved traitor tracing scheme based on modified RSA

MA Hua(1);YANG Bo(2)

J4. 2006, 33(3):  422-424. 

Abstract ( 1691 )   PDF (116KB) ( 766 )   Save

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An improved traitor tracing scheme based on modified RSA is proposed, which solves the existing schemes problem
of fixed session key by introducing a random number with its security improved. Meanwhile, the new traitor tracing scheme is
reconstructed by modified RSA algorithms and its efficiency is also improved. The proposed scheme allows efficient
deterministric traitor tracing to recover all traitors.

Study of the infinite element-domain decomposition method in electromagnetic scattering of cylinders

AN Xiang(1);Lü Zhi-qing(2);LIANG Chang-hong(1)

J4. 2006, 33(3):  425-429. 

Abstract ( 1937 )   PDF (206KB) ( 912 )   Save

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A new algorithm based on the infinite element-partial basic solution vectors domain decomposition
method(IEM-PBSV-DDM) is presented for solving electromagnetic scattering problems of electrically large cylinders. The
infinite element method is introduced to truncate the computational space, which decreases the number of unknowns on each
subdomain and the number of nodes on the interface boundaries significantly. The partial basic solutions of the nodes on the
interface boundaries of contiguous subdomains are solved in advance, and then the original solution could be trivially
obtained by a simple vector summation procedure. Compared with the traditional method, the presented method can reduce the
computation time and memory requirement greatly.

Study of the shadowing technique in the NURBS-PO method

CHEN Ming;ZHANG Yu;WANG Nan;LIANG Chang-hong

J4. 2006, 33(3):  430-432. 

Abstract ( 1898 )   PDF (141KB) ( 986 )   Save

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The NURBS PO applies the PO method on the NURBS surface to compute the field and radar cross section (RCS).
Shadowing is one of the key problems in the physical optics method. In this paper, an effective algorithm is present to solve
the shadowing problem in the NURBS-PO method. Numerical examples show the validity of this algorithm. This algorithm can also
be applied to the PO method which uses triangle patch modeling to accelerate the computing speed.

Estimation of yield associated with elliptical defect

WANG Jun-ping(1;2);HAO Yue(1);ZHANG Zhuo-kui(3);Ren Chun-li(3);LI Kang(1);FANG Jian-ping(1)

J4. 2006, 33(3):  433-437. 

Abstract ( 1511 )   PDF (187KB) ( 770 )   Save

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In integrated circuits, the defects associated with photolithography are assumed to be the shape of circular
discs in order to perform the estimation of yield and fault analysis. However, the shape of 70% real defects approximates
elliptical shapes. This paper provides a yield model caused by elliptical defects. The model is more general than that of the
circular defect as the model is only an instance of the new model. A comparison result between the two models in experiment
shows that the new model may predict the yield caused by real defects more accurately than the circular model does, which is
of significance for the prediction and improvement of the yield.

A novel construction algorithm for symmetrical reversible variable length codes

HUO Jun-yan(1);CHANG Yi-lin(1);MA Lin-hua(1);LUO Zhong(2)

J4. 2006, 33(3):  438-441. 

Abstract ( 1588 )   PDF (140KB) ( 774 )   Save

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A novel construction algorithm for symmetrical Reversible Variable Length Codes (RVLC) is proposed based on the
analysis of the symmetrical RVLC code tree, which is independent of the Huffman code. The algorithm adds all candidate codes
into the queue after the minimum codeword length is obtained according to the symbol probability, then selects those which
satisfy the codeword mechanism as symmetrical RVLCs. The result shows it can lead to a smaller average code length, and has
the advantages of flexible codeword selection mechanism and easy realization.

On simplified liveness-enforcing Petri net supervisors for FMS

LI Zhi-wu;XU Ping-jiang;ZHU Rong-ming;WANG Xing-ping

J4. 2006, 33(3):  442-447. 

Abstract ( 1817 )   PDF (264KB) ( 885 )   Save

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This paper develops a deadlock prevention policy for a class of Petri nets, which can model a wide class of
flexible manufacturing systems, where deadlocks are caused by unmarked siphons. We distinguish emptiable siphons in a plant
Petri net model by elementary and dependent ones. By adding a control place(monitor) for each elementary siphon, all
dependent siphons can be controlled by adjusting control depth variables of elementary siphons. A prior condition is
developed under which a dependent siphon can be implicitly controlled. Furthermore, by structural analysis and optimization
design of a supervisor, a method is proposed to decide whether an additional control place is redundant. By removing
control-redundant control places, a simplified liveness-enforcing supervisor with more permissive behavior can be obtained.

A study of the security of a steganography method and security enhancement methods

LU Ming-xin(1);FU Xiao-tong(1);QIN Lei(2);XIAO Guozhen(1)

J4. 2006, 33(3):  448-452. 

Abstract ( 1591 )   PDF (195KB) ( 831 )   Save

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Based on PCR and DNA sequencing technology, several attacks against a DNA steganography method are proposed and
discussed. Due to the limitation of finding complementary primes, electrophoretic technology and separation technology,
attacks above do not work. The attact by using possible words as primes is also discussed, and security enhancement methods
to prevent such attacks are proposed.

The mode of network organization design based on the optimization organization unit

WANG An-min;XU Guo-hua

J4. 2006, 33(3):  453-457. 

Abstract ( 1503 )   PDF (184KB) ( 872 )   Save

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From the trade of the advanced manufacturing mode and the change of organization, the conception of optimization organization unit is defined, which applies Socio-Technical System, modern organization management and organizational economics synthetically. The mathematical programming model of optimization organization unit is built by quantifying the cost of technique, manpower and organization. This model is subject to the interaction between the technical system and social system. Then the mode of network organization design based on the optimization organization unit is given. The mode improves the methods of team and network organization design. It can achieve the coordinated optimization of socio-technical factors in organization, and make the organization have both dynamic reconstruction and stability.

Berengers perfectly matched layer for the alternating direction implicit finite-difference time-domain method

WANG Lin-nian;CHU Qing-xin;LIANG Chang-hong

J4. 2006, 33(3):  458-461. 

Abstract ( 1746 )   PDF (164KB) ( 888 )   Save

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This paper presents a new scheme, which is used in discretizing Berengers split field representation of Maxwell’s equations, in order to use the perfectly matched layer(PML) with the alternating direction implicit(ADI) finite-difference time-domain(FDTD) method instead of the standard FDTD method. Compared with the discretization scheme proposed earlier, the new one makes the reflection errors of PML absorbing boundary condition decrease by orders of magnitude when a larger time step is used.

The effect of the inaccuracy in line of fiber optic F-P sensing head on SNR in fabry-perot sensor

YANG Yao-en(1;2);LIU Ming-zhi(1);WANG Qing-min(2);SUN Bao-chen(2)

J4. 2006, 33(3):  462-465. 

Abstract ( 1770 )   PDF (159KB) ( 777 )   Save

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When fiber optic Fabry-Perot strain sensor undergo strain in engineering, the effect from the malposition of the sensing head on the Signal Noise Ratio(SNR) is discussed in this paper. The effect power changes with the malposition in line, and makes the SNR changeable. The mathematical analytical model is founded by using the electro magnetic theory and the numerical simulation is carried by using a computer. The results are that the larger the malposition, the higher the SNR. When the malposition in line is near to 0.1, th SNR will tend to be relatively stable and the sensor will be ineffective. An experiment is carried to prove the theory and both results are almost identical.

Detection of number of sources via exploitation of non-circular property

ZHENG Chun-di(1;2);FENG Da-zheng(1);ZHOU Yi(1)

J4. 2006, 33(3):  466-470. 

Abstract ( 1916 )   PDF (206KB) ( 899 )   Save

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We present in this paper a new number-of-sources-detecting algorithm for non-circular sources. In the proposed method, due to the non-circularity characteristics of the sources, we can employ the conjugate measurements and unitary transformation in the covariance matrix, and as a result the sensors and snapshots are doubled. It is shown that the new method can handle more sources than the MDL, and that it has a better angular resolution. In addition, the rate of convergence of the proposed method is faster than that of conventional algorithms.

A multi-service oriented collusion-resistant asymmetric public-key traitor tracing scheme

ZHANG Xue-jun(1;2);ZENG Zhi-yong(1);ZHOU Li-hua(1)

J4. 2006, 33(3):  471-475. 

Abstract ( 1388 )   PDF (175KB) ( 868 )   Save

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The session key S is divided into a sum of S₁ and S₂. Under the condition of a large integer factoring problem, S₁ is decrypted by constructing a special polynomial function (scheme 1). Under the condition of the discrete logarithm problem, S₂ is decrypted by the Chinese Remainder Theorem(scheme 2). On the basis of a combination of scheme 1 and scheme 2, a new traitor tracing scheme is formed, which has advantages of both of them, meanwhile it overcomes their disadvantages. It has many advantages such as multi-service, collusion-resistance, asymmetry, long-lived subscriber’s key and black-box tracing.

An algorithm for image enhancement based on shock filters and anisotropic diffusion

JIANG Ling-ling;YIN Hai-qing;FENG Xiang-chu

J4. 2006, 33(3):  476-478. 

Abstract ( 1823 )   PDF (237KB) ( 922 )   Save

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A new scheme is presented by the coupling between shock filters and anisotropic diffusion. The main idea is to add some sort of anisotropic diffusion term with an adaptive weight between the shock and diffusion processes. The method can not only well restrain noise but also enhance edge and keep much more details of an image. The filter is directly given in the form of discretization so that it is easy to implement and the processing time is greatly saved.

Reducing the RCS of the microstrip antenna by cutting slots and loading a shorting-post

RONG Feng-mei;GONG Shu-xi;HE Xiu-lian

J4. 2006, 33(3):  479-481. 

Abstract ( 2378 )   PDF (147KB) ( 1061 )   Save

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The miniaturization technique of cutting slots and loading a shorting-post in the microstrip patch is used for the radar cross section(RCS) reduction of an antenna. It can reduce the working frequency and overall size of the antenna, which reduces the RCS by restraning structure mode scattering. Simulation results by applying the technique the microstrip antennas show that the RCS can be reduced about 4dB and the gain loss is less than 0.4dB, which illustrates that the compact antenna can not only guarante the antenna radiation performance, but also reduce the RCS of the antenna significantly at its working frequency.

Study of the technique of the embedded Web server based on the AT91M40800 micro-controller

XUAN Rong-xi(1);YING Zhe(2)

J4. 2006, 33(3):  482-485. 

Abstract ( 1646 )   PDF (154KB) ( 788 )   Save

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This paper studies the technique of the Web server in the Embedded system for its application. Based on the AT91M40800 micro-controller, it presents the structures of the hardware and the software of the Embedded Web Server(EWS). It describes the design and the implementation of the EWS in detail, and also gives an example of the EWS application in the power monitoring and controlling system. Moreover, the security methods in the EWS application are discussed. The engineering practice shows that the application system with the EWS breaks through the restriction of traditional communication technique, and raises the efficiency of information usage.

A new information reconciliation protocol

WANG Bao-cang(1);YANG Bo(2);HU Yu-pu(1)

J4. 2006, 33(3):  486-490. 

Abstract ( 1624 )   PDF (162KB) ( 784 )   Save

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The substrings of a bit-string can be regarded as binary numbers on which a digit-sum operation is defined. By comparing the digit-sums of the two substrings, one can locate and correct the error in his substring. The efficiency of our new protocol is much higher than those of all known information reconciliation protocols even in the worst case, and simultaneously, its information leakage is relatively small.

The condition for generalized saddle points for multiobjective optimization problems in topological vector space

YU Guo-lin(1;2);LIU San-yang(1)

J4. 2006, 33(3):  491-494. 

Abstract ( 1631 )   PDF (156KB) ( 832 )   Save

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Based on the importance of saddle points in theory and application for multiobjective optimization problems, this paper introduces a new kind of generalized saddle points and points out that other saddle points belong to a special case. By using the properties of a cone, the discriminant condition and some properties of generalized saddle points are obtained.

Adaptive repetitive learning control for a class of second order nonlinear time-varying systems with mixed parameters

SUN Yun-ping;LIU Yun;LI Jun-min

J4. 2006, 33(3):  495-499. 

Abstract ( 1908 )   PDF (204KB) ( 807 )   Save

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A novel adaptive repetitive learning control for second-order nonlinear systems with time-varying and time-invariant parameters is proposed by using the Backstepping approach. It can be applied to the time-varying parametric uncertainty systems with an unknown compact set, which are non-vanishing, rapid time-varying, and periodic and where the prior knowledge is the periodicity only. A periodic mixed adaptive law and an adaptive repetitive learning control one are constructed to ensure the asymptotic convergence of the tracking error in the sense of square error norm. Also, a sufficient condition for the convergence of the method is given. A simulatioin example illustrates the effectiveness and the feasibility of the proposed method.

Study of the construction and application of the DEM

LIU Nan-yan;ZHAI Ling

J4. 2006, 33(3):  500-503. 

Abstract ( 1346 )   PDF (188KB) ( 943 )   Save

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The paper puts forward the general concept of DEM first, and then studies the building process of DEM, data collecting process of DEM and data constructing process of DEM. Finally, the use of DEM in a real engineering project is explained, including drawing the sectional drawing, computing the easy cubic mete of the earth, the statistics of surface area in slope, drawing the gird map of three dimensions and computing the surface area, with the paper mainly introducing the drawing of the grid map of three dimensions and the statistics of the surface area of the slope using OpenGL.

Automatic extraction of gullies and cliffs from topographic map

YANG Yun(1;2);ZHU Chang-qing(2);SUN Qun(2);ZHANG Zi-jing(3)

J4. 2006, 33(3):  504-508. 

Abstract ( 1518 )   PDF (212KB) ( 834 )   Save

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In GIS geospatial data acquisition, there are many map scanning digitizing systems in which automatic tracking method is used for digitizing contour lines. The performance is, however, far from satisfactory because a great deal of editing is involved. In this paper, we analyze two map symbols: the gully and the cliff, which greatly affect the efficiency of automatic digitization, and propose a new method called revolving inner tracking for extracting gullies and cliffs from separated contour images. Experimental results show that the proposed method has greatly improved the efficiency and the accuracy of digitizing the two symbols. The method has been successfully applied to 1∶50000 scale map digitizing production.