Table of Content

20 August 2008 Volume 35 Issue 4

  

Original Articles

Study of the distributed scheduling algorithm based on the mixed switch mechanism in a three-stage Clos network


YANG Jun-Gang1;2;LIU Zeng-ji1;GU Hua-Xi1;ZHAO Rui-Qin1;LUO Xiao-Zhuo1

J4. 2008, 35(4):  581-585. 

Abstract ( 2259 )   PDF (616KB) ( 1222 )   Save

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A new distributed scheduling algorithm in a three-stage Clos network is proposed, which combines the varied length packet and fixed length cell switch mechanism. This algorithm adopts the load-allotment scheme based on the varied length packet and a new token scheme in the input stage, which removes the cells of a packet mis-sequence in the cell switch mechanism and unfair load-allotment in the packet switch mechanism, the scheduling scheme in the central stage and output stage switches based on the fixed length cell switch mechanism, which improves the algorithm efficiency and raises the algorithm adaptability. The algorithm stability is shown by theoretical analysis. The simulation analysis demonstrates that the algorithm outdoes other algorithms in delay and adaptability.


High speed ground moving target detection research using triangular FMCW modulation


LIANG Yi;ZHOU Feng;XING Meng-dao;BAO Zheng

J4. 2008, 35(4):  586-591. 

Abstract ( 1852 )   PDF (1095KB) ( 1293 )   Save

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The Frequency Modulation Continuous Wave (FMCW) radar has the characteristics of low probability of interception, good hidden property and ability to counter anti-radiation missiles. This paper proposes a new method for high speed ground moving target detection using triangular FMCW modulation. According to the characteristic of the reverse range shift induced by the upslope and downslope of triangular FMCW modulation, the upslope and downslope are imaged, respectively. After compensation of continuous motion of the platform and time difference between upslope and downslope signals for imaging, the moving target can be detected through displaced phase center antenna(DPCA) technology. When the moving target is detected, we extract the moving target image, and use the correlation processing to get the range shift, which can help to estimate the target range velocity, and to find the real position of the target. Computer simulation verifies the validity of the method.


Randomicity analysis of the piezothermoelasticity intelligent thin plate by appling the numerical method


WANG Xiao-bing;CHEN Jian-jun;LIANG Zhen-tao;CHEN Yong-qin;XIE Yong-qiang

J4. 2008, 35(4):  592-599. 

Abstract ( 1974 )   PDF (947KB) ( 1012 )   Save

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For the piezothermoelasticity intelligent thin plate, a cube finite element model including 4 displacement nodes, 2 electric potential nodes and 8 temperature nodes is presented, its displacement field is defined by means of the plane shell element model, and its electric potential field and temperature field are both defined by means of linear interpolation. The finite element equations are deduced by applying the virtual work principle. When parameters are random and the moment method is used to obtain response’s numerical characteristics, in order to avoid the difficulty of sensitivities computation on the response’s analytical solution, the finite element equations are translated to state equations, and the sensitivity differential equations are obtained from the derivative of state equations. Then, the sensitivity at each discrete time is obtained by making use of the deference method. An intelligent cantilever plate is taken as an example, and the numerical results show that the computing process presented has good precision and fast calculation speed.


Simulation of the sea clutter and an analysis of temporal and spatial correlation at a high grazing angle


QIN Guo-dong;CHEN Bo-xiao;CHEN Duo-fang

J4. 2008, 35(4):  600-604. 

Abstract ( 1943 )   PDF (804KB) ( 1018 )   Save

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The high-resolution sea clutter is produced at high grazing angles by using the Neumann-Pierson sea surface model. The amplitude distribution and average Doppler frequency of the sea clutter produced are analyzed. The temporal and spatial auto-correlation functions are formulated, and then the correlation is analyzed. Some results are obtained with the beam in the Ku-band illuminating the sea surface in some sea state. The amplitude of the sea clutter obeys the χ₂ distribution; the spectrum is widened at the shifted central frequency of 30Hz; the sea clutter has strong correlation in time and space, and the correlation time is about 20ms.


Novel algorithm for the processing of non-uniform motion SAR data


JING Wei;ZHANG Lei;XING Meng-dao;BAO Zheng

J4. 2008, 35(4):  605-608. 

Abstract ( 1986 )   PDF (778KB) ( 1082 )   Save

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A new algorithm is presented. Based on the concepts of the wave-number and instantaneous slant range, a precise 2-dimension (2-D) frequency analytical formula is developed by calculating the integral of the echoes along platform trajectory sampling positions, and finally the traditional imaging algorithm is used to focus the image. The algorithm suits any case if one knows the platform trajectory sampling positions, and it can obtain high precision for the absence of interpolation. This algorithm is compatible with the traditional imaging processing easily. Simulations show the validity of the algorithm.


Web service automatic composition algorithm based on Petri nets


MEN Peng;DUAN Zhen-hua

J4. 2008, 35(4):  609-613. 

Abstract ( 1685 )   PDF (542KB) ( 1004 )   Save

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Web service automatic composition algorithm based on Petri nets


Secure electronic auction scheme based on the group signature


ZHANG Yue-yu;LI Hui;WANG Yu-min

J4. 2008, 35(4):  614-619. 

Abstract ( 1973 )   PDF (544KB) ( 1091 )   Save

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Based on Linear Cramer-Shoup encryption, a new short group signature is proposed. The anonymity property of this scheme is secure against adaptive chosen-ciphertext attacks (CCA2), which allows the adversary to open the signature when trying to break the anonymity notion. Using this group signature as a building block, a secure electronic auction scheme is designed. Under the same security conditions, the scheme has sizes of signature, group public key, signing key, register key and tracing key 1／14, 1／7, 1／17, 1／40 and 1／4 those of the scheme based on the RSA problem. Compared with the pairing-based scheme in which the bidder’s anonymity is CPA secure, the complexities of communication and computation in this paper are approximate to those in the former, but the CCA2-full-anonymity of bidders is achieved in this new scheme.


Novel curvature-compensated CMOS bandgap reference based on the negative feedback clamp technique


CAO Han-mei1;YANG Yin-tang1;CAI Wei2;LU Tie-jun2;WANG Zong-min2

J4. 2008, 35(4):  620-623. 

Abstract ( 1888 )   PDF (619KB) ( 1075 )   Save

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A novel high-performance curvature-compensated CMOS bandgap reference is presented. Instead of Differential-Amps used in typical structures, the negative feedback technique is used to clamp node voltages, thus simplifying the design. A regulated cascade configuration is used to improve the power supply rejection ratio (PSRR). The entire circuit is implemented in SMIC standard 0.18μm CMOS process. Results from HSPICE simulation show that the temperature coefficient between -45℃～125℃ is 12.9×10^-6／℃, and that the PSRR is 67.2dB at 10Hz. The design can be applied to high-speed analog-to-digital converters.


SAR image segmentation using weighted PCM clustering based on direction flow field with visual character


TIAN Xiao-lin;JIAO Li-cheng;GOU Shui-ping

J4. 2008, 35(4):  624-631. 

Abstract ( 2518 )   PDF (1789KB) ( 1162 )   Save

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Because of the influence of the speckle in the synthetic aperture radar (SAR) image, both the statistical dependencies among neighboring pixels and spatial adaptation of the clustering prototype should be considered during the process of SAR image segmentation. So it is required that the membership and spatial information should be combined. The adaptive spatial neighbor weighted possibilistic c-means (PCM) clustering based on the direction flow field is proposed in the paper. The direction flow field is constructed by combining the predictive coding model with the visual character and steerable wavelet transform. The relationship between the pixel under test and the pixels of neighborhood is described through Markov random fields (MRF) based on the direction flow field. Because the context information is considered, membership is adjusted efficiently. The experimental results on real SAR images demonstrate the merit of the proposed method, especially in despeckling and the preservation of details within a SAR image.


Effective algorithm for obtaining a set of elementary siphons


WANG An-rong;LI Zhi-wu

J4. 2008, 35(4):  632-638. 

Abstract ( 1828 )   PDF (609KB) ( 988 )   Save

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Elementary siphons are computationally expensive when the size of a Petri net is large. Based on binary search, this paper proposes an efficient algorithm for finding a set of elementary siphons. If the characteristic T-vector matrix of a net is not of row full rank, the matrix is divided into two sub-matrices. This step is repeated until a row full rank sub-matrix is found. The siphons corresponding to the sub-matrix are elementary. Based on these elementary siphons, other elementary siphons can be accordingly found by recursive search in the sub-matrices. This algorithm ensures that the number of times of calculating the ranks of matrices is greatly reduced compared with the traditional sequential search method. For the linear simple sequential process with resources (LS³PR), it is polynomial. Finally, the efficiency is demonstrated by case study.


Mix Net with revocable anonymity


LI Long-hai1;2;XIAO Guo-zhen2

J4. 2008, 35(4):  639-644. 

Abstract ( 2014 )   PDF (566KB) ( 971 )   Save

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A new method for achieving revocable anonymity in re-encryption mix networks is presented. Each sender is required to append his identity information encrypted under the public key of an anonymity revocation authority to every ciphertext submitted by him. Then ciphertexts from different senders, as well as their encrypted identities, are re-encrypted and shuffled together by the mix net. The adjusted secret shuffle proof protocol can guarantee the bindings of these two types of ciphertexts in the mixing process. In the output phase, a quorum of mix servers jointly decrypts every normal ciphertext and generates a threshold signature to keep the correspondence between every output message and its sender’s re-encrypted identify. When tracing a vicious message, the anonymity revocation authority just needs to decrypt its corresponding encrypted identifies. Compared with the previous work, our method needs only 1 additional ElGamal pair and involves less exponential computation and communication.


Hardware-oriented rate control algorithm for JPEG2000 and its VLSI architecture design


LEI Jie;KONG Fan-qiang;WU Cheng-ke;LI Yun-song

J4. 2008, 35(4):  645-649. 

Abstract ( 2373 )   PDF (785KB) ( 1101 )   Save

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For the purpose of decreasing the quantity of operation and reducing the size of memory, a new rate control algorithm for JPEG2000 is proposed utilizing the rate pre-allocation method, the VLSI architecture design of which is given as well. After wavelet transform and quantification on the original image, a prediction module is introduced to estimate the entropy of the EBCOT code block within the available bit-plane, and then the proportion between the estimate entropy of each code block and the summation estimate entropy of all code blocks is used to allocate the rate for each code block. EBCOT coder truncates the code stream according to the allocated rate, and thus the operation time consumed by the T1 coder is reduced. After coded by the T1 coder, each code block can be packed to the output, with no need for computing the rate-distortion slope and completing the rate-distortion optimization truncation. Experimental results show that the proposed algorithm can efficiently reduce the cost of computation and memory usage, and that it is most suitable for hardware implementation.


Analysis of inner evolving networks


LIU Yong-kui;LI Zhi;CHEN Kang

J4. 2008, 35(4):  650-653. 

Abstract ( 1656 )   PDF (476KB) ( 972 )   Save

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The effects of inner edge addition on the structure of the Barabasi-Albert(BA)scale-free network are analyzed, with the linear and non-linear preferential attachment. Based on the extended rate-equation approach, considering the changing rates of the existing nodes’ degrees caused by the addition of new nodes and edges, the exact expressions for the degree distributions are obtained. When the preferential attachment is linear, the degree distributions follow the power-law form. For the sub-linear preferential attachment, the degree distributions follow the form of stretched exponential; for the sup-linear preferential attachment, the double-end-point preferential attachment can lead to an extremely low number of “gel” nodes connecting to nearly every other node in the network. The results obtained provide references for further researches on other properties of inner evolving networks.


Novel internal chip antenna with a penta-band for the mobile handset


LIU Ying1;GONG Shu-xi1;FU De-min1;Hyeongdong Kim2

J4. 2008, 35(4):  654-657. 

Abstract ( 1527 )   PDF (1035KB) ( 1126 )   Save

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An internal penta-band chip antenna for GSM850／GSM900／DCS1800／PCS1900／UMTS is presented. The resonance frequencies of the spiral line and meander line printed on the FR-4 with dielectric permittivity of 4.4 are combined to realize the wide frequency band. The bent line structure realizes the size reduction. The antenna occupies the volume of 20mm×8mm×3.2mm which is fit for the internal antenna of a mobile cell phone. The size of the circuit board is 40mm×93mm for the recent small cell phone. The measured bandwidth with VSWR＜3 is 146MHz(1030~1176MHz) in the lower frequency band and 530MHz(1756~2286MHz) in a higher band.


Application of non-Maxwellian distribution for the ion velocity in calculation of incoherent scattering spectra in high-latitude ionosphere


XUE Kun1;GUO Li-xin1;WU Jian2;XU Bin1

J4. 2008, 35(4):  658-663. 

Abstract ( 1778 )   PDF (705KB) ( 965 )   Save

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It is found that distortions are produced for Maxwellian distribution of the ion velocity distribution due to a large convection electric field appearing in the high latitude region. In this paper, an analytical form of Non-Maxwellian ion velocity distribution in the line-of-sight direction is used. According to the incoherent scattering theory, the incoherent scattering spectral is derived and computed. This study shows that the analytical Non-Maxwellian distribution function can simplify the calculation of the incoherent scattering spectral and improve the velocity of computing incoherent scattering spectra.


Design and analysis of a CC scheme with high-order constellations over slow-fading rayleigh channels


GONG Feng-kui;HAN Chun-lei;WANG Yong;GE Jian-hua

J4. 2008, 35(4):  664-667. 

Abstract ( 2187 )   PDF (671KB) ( 1212 )   Save

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A high-efficient coded cooperative (CC) scheme with high-order constellations is proposed. In this scheme, encoded bits of the user or the partner are partitioned, bit interleaved, mapped on a high-order two-dimentional constellation and then transmitted on the allocated time slots. The pairwire error probability over slow-fading Rayleigh channels are derived. Both theoretical analysis and simulations show that the coded cooperation with high-order constellations can achieve full diversity with an improved spectrum effciency over slow-fading Rayleigh channels.


3-D baseline error estimation method for distributed small satellites


XU Qing1;LIAO Gui-sheng1;LIU Ying1;LIANG Jing2

J4. 2008, 35(4):  668-672. 

Abstract ( 1949 )   PDF (622KB) ( 1066 )   Save

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In 3-D distributed small satellites, the along-track baseline couples with the vertical-track ones, which makes it difficult to estimate them, respectively. A new 3-D baseline error estimation method for distributed small satellites is proposed in this paper. This method separates the two kinds of baselines through image registration in the field of the image and estimates the two kinds of baseline errors by image registration and subspace decomposition, respectively. The method is easy to operate with a small amount of computation. The mm-level precision can be achieved.


Research on the accurate measurement method for the antenna phase center


SHANG Jun-ping;FU De-min;DENG Ying-bo

J4. 2008, 35(4):  673-677. 

Abstract ( 4299 )   PDF (906KB) ( 2510 )   Save

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Based on the measured radiation pattern data of the antenna, a ralationship between phase offset and positional deviation of the phase center is founded by means of changing the reference point. Using the least square method, we can compute the phase center deviation for the antenna.Finally, a suit of test system is developed.The measured result and the error analysis indicate that the proposed method can accurately measure the phase center of the antenna,with the measuring accuracy less than 1mm.


Method for waveform design based on mutual information


JIU Bo;LIU Hong-wei;LI Li-ya;WU Shun-jun

J4. 2008, 35(4):  678-684. 

Abstract ( 2056 )   PDF (634KB) ( 1130 )   Save

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A novel method termed General Water-Filling is proposed to solve the waveform design problem of a broadband radar for estimating multiple extended targets, which is suitable when the clutter is not negligible. The uncertainty about the target characteristics decreases by maximizing the mutual information between a random extended target and the received signal. Then the General Water-Filling method is employed to the waveform design problem for multiple extended targets identification so as to increase the separability of multiple targets. The results of simulations evaluate the efficiency of the proposed method. Compared to the chirp and Water-Filling signal, our method improves the classification rate by about 3 percent and even performs better in the case of a low SINR.


Implementation of high stability with on-chip frequency compensation in a current mode DC-DC converter


YUAN Bing1;2;LAI Xin-quan2;JIA Xin-zhang1;YE Qiang2;WANG Hong-yi2

J4. 2008, 35(4):  685-690. 

Abstract ( 1942 )   PDF (938KB) ( 1202 )   Save

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An on-chip frequency compensation structure for the current mode DC-DC converter is presented. With an integrated RC network, it realizes the loop frequency compensation and overcomes the drawback of stability dependency on load resistance due to the output ceramic capacitor’s low effective series resistance, which reduces the pin numbers, saves the PCB space and stabilizes the chip. Also the optimized feedback network makes the crossover frequency insensitive to the change of the output voltage, improving the load step response further. A DC-DC buck converter with a proposed structure has been fabricated with a 0.5 μm CMOS process for validation. The measurement results show good stability. Both load and line regulations are less than 0.4％. And the output voltage can be recovered within 8 μs for a 400 mA load step. The occupied PCB space is also reduced 14％.


Improved iterative channel estimation and a decoding algorithm for the STBC-OFDM system


ZHENG Yong;FENG Da-zheng

J4. 2008, 35(4):  691-695. 

Abstract ( 1849 )   PDF (682KB) ( 999 )   Save

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A low-complexity joint channel estimation and a decoding algorithm for the space-time block coded orthogonal frequency division multiplexing (STBC-OFDM) system in unknown channels is presented. Different from the decoding via exhaustive searching in the previous iterative maximum-likelihood (ML) receiver, in the new algorithm, the signals are estimated analytically, and then are quantized with the aid of the finite alphabet information. The proposed iterative algorithm only involves linear processing and exploits the special orthogonal structure of the STBC-OFDM signal. For a system with two receive antennas, if the Alamouti STBC and 8-PSK signal are adopted, the proposed method has 1／16 the complexity compared with the searching method. As the system complexity increases, the new method has more advantages over the searching method. Simulation results show that our method only has a little performance loss. On the other hand, by simulation, two applications of the new method on time-varying channel tracking and improving the performance of the system with an inserted pilot are given.


New fusion algorithm for multispectral and high-resolution panchromatric images


BAI Rui;YANG Wan-hai;ZHANG Yan-ni

J4. 2008, 35(4):  696-702. 

Abstract ( 2181 )   PDF (1025KB) ( 1358 )   Save

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A Multispectral and High-resolution Panchromatic image fusion algorithm based on the DT-CWT transform and fractal dimension is developed. Firstly, the panchromatic images and the component I of the multi-spectral image are decomposed to the domain of the DT-CWT transform which has the advantage of good directions, and the image fusion is then implemented in different subbands. The region energy fusion algorithm is adopted as fusion rules in low-pass subbands and high-pass subbands, and images are merged with different fractal dimension as weight. Finally, the stretched grayscale fused image replaces the original intensity component, and the final fused image is achieved. Compared to the traditional HIS transform and wavelet based algorithm, the warp of the proposed algorithm is only 30.31％ and 50.66％ the formers, respectively.


Coupling matrix method for diagnosis and tuning of microwave filters


HAN Ying-bin1;ZHAO Yong-jiu1;LU Hong-min2

J4. 2008, 35(4):  703-706. 

Abstract ( 2039 )   PDF (630KB) ( 1626 )   Save

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The traditional model-conformation method for microwave filter diagnosis is not suitable for the exact synthesis, so a modified method for the general Chebyshev filter is proposed, i.e., a reasonable restriction has been imposed on the coefficients of the numerator polynomials in both transfer and reflection functions. Afterwards, the coupling matrix of the filter can be evaluated. Thus the tuning direction and magnitude of corresponding physical structures can be determined by comparison with the designed coupling matrix. Finally, two processes of diagnosing and tuning a four-order microstrip square open-loop filter and an eight-order waveguide filter are demonstrated with the help of the modified diagnosis method, and the response of the filter tuned is fine. The return loss and group delay specification are both achieved, and the consumption of the tuning time is also shortened by a half.


Geometric resistant image watermarking algorithm based on local feature regions


DENG Cheng1;2;GAO Xin-bo1;FAN Ke-feng3;ZHOU Fang1

J4. 2008, 35(4):  707-711. 

Abstract ( 2468 )   PDF (937KB) ( 1178 )   Save

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A new digital watermarking method resistant to geometric attacks is proposed, in which the feature points are extracted by an affine-invariant point detector, and then watermarks are embedded into the affine invariant regions centered at these feature points. For further procedure, a novel FIS (Fuzzy Inference System) is employed to adaptively adjust the embedding strength in those regions. The validity of the method is confirmed by a number of experiments. Simulation results confirm the robustness of our proposed method to different attacks, such as common image processing, rotation, scaling, cropping, and several other affine transformations.


Analysis of the bound performance of systematic regular RA codes in the BEC Channel


SUN Rong;LIU Jing-wei;WANG Xin-mei;MU Jian-jun

J4. 2008, 35(4):  712-715. 

Abstract ( 2051 )   PDF (552KB) ( 1786 )   Save

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This paper introduces the construction of systematic regular RA codes and makes a brief analysis of the bound of the systematic regular rate-1／2 RA codes for binary erasure channels. The asymptotical performance of such codes is given and the union bound is simulated. The analytical and simulation results show that the structure of the regular RA code plays a great role in the performance of the code.


Stopping algorithm for iterative decoding based on the average extrinsic information exchange for SCCPM


SUN Jin-hua;LI Zi-yi

J4. 2008, 35(4):  716-720. 

Abstract ( 2381 )   PDF (722KB) ( 1028 )   Save

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In order to decrease the positive feedback of the Serially Concatenated Continuous Phase Modulation (SCCPM), a new stopping algorithm for iterative decoding based on the average extrinsic information exchange is proposed. The algorithm uses the method for average extrinsic information exchange, which makes the mean of extrinsic information of all previous iterations a priori information for the next iteration, and then it performs decoding with two stopping criterions of dynamic iterative decoding: Sign Change Ratio (SCR) and Hard Decision-Aided (HDA). Simulation result shows that the proposed algorithm with dynamic iterative stopping criteria can resist the positive feedback and improve BER performance as well as reduce the iterative decoding delay.


Multi-object optimization routing algorithm based on fuzzy decision making for wireless sensor networks



MI Zhi-chao1;2;BAO Min-quan3;ZHOU Jian-jiang1

J4. 2008, 35(4):  721-725. 

Abstract ( 2427 )   PDF (624KB) ( 1197 )   Save

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According to the characters of wireless sensor networks, a multi-object integer programming model based on fuzzy decision making is formulated to optimize the energy and delay of the path. An objective satisfaction degree function is introduced to estimate the objective similarity degree. Based on this function, a multi-object optimization routing algorithm is proposed. The algorithm can adjust and compress the satisfaction degree space to satisfy well the different requirements of various services for energy and delay of the path. An example demonstrates the effectiveness. Finally, simulation results show that compared with the minimum delay routing algorithm and minimum power routing algorithm, the proposed algorithm is a better approach in terms of comprehensive performance of the power-delay satisfaction degree function.


Novel inter-carrier interference mitigation scheme for OFDM systems


CHEN Na-quan;ZHANG Jian-hua;ZHANG Ping

J4. 2008, 35(4):  726-732. 

Abstract ( 1923 )   PDF (759KB) ( 1084 )   Save

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In high-speed mobile environment, the inter-carrier interference (ICI) caused by the Doppler effect degrades the performance of the orthogonal frequency division multiplexing (OFDM) system. In order to lessen the severe effects of ICI, a novel ICI mitigation algorithm is proposed, which is called the time-domain ICI self-cancellation (TDISC). In this algorithm, the repeated symbol is used at the transmit side, and large numbers of reconstructed OFDM symbols with different additional delays are obtained by some manipulations of the received data, and then diversity combination of these reconstructed OFDM symbols is applied by using the channel statistic property at the receive side, and thus the system performance of ICI suppression is improved. Through simulations and analyses, it is proved that the TDISC can effectively combat the ICI, improve system performance and, consequently, be an effective solution to the implementation of OFDM in high-speed mobile environment.


Motion control research on the omni-directional-mobile manipulator


JIANG Lin;YAN Ji-hong;ZANG Xi-zhe;ZHAO Jie

J4. 2008, 35(4):  733-738. 

Abstract ( 1762 )   PDF (1294KB) ( 1111 )   Save

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To improve the task completion efficiency of the omni-directional mobile manipulator (ODMM), timing motion planning and control strategy based on absolute positioning (TMPCSAP) is proposed. Firstly the CAN bus is used in the control structure, and in this way the control accuracy and response speed of ODMM can be improved. Secondly the control of ODMM about omni-directional motion, point-turn motion and mechanical arm’s motion is studied. Thirdly ultrasonic-timing-absolute-positioning is used in the control strategy of TMPCSAP to adjust and optimize the control variable, and in this way the task completion efficiency can be improved. Finally three experiments are done; two motion accuracy experimental results show that the motion accuracy of ODMM is high; one control strategy experimental result confirms the validity of the control strategy of TMPCSAP.


Key management scheme for WSN using ECC


DING Yong

J4. 2008, 35(4):  739-742. 

Abstract ( 1858 )   PDF (516KB) ( 1337 )   Save

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With the development of related technology, public key cryptosystem can also be utilized to build the security mechanism of WSN. With the integration of signature and key exchange of ECC, we propose an efficient key management scheme for WSN. An analysis shows it is of high security and efficiency. It can also guarantee the connectivity and flexibility of the network. Moreover, it meets the requirement of the limited computation and storage resource of the WSN node.


Study of configuration matching strategy in self-reconfigurable robots based on the graded optimization mechanism


REN Zong-wei;ZHU Yan-he;ZHAO Jie;ZHANG Yu-hua

J4. 2008, 35(4):  743-748. 

Abstract ( 2233 )   PDF (961KB) ( 957 )   Save

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The self-reconfigurable theory is an important research domain in the study of self-reconfigurable robots. The modules in existence only have limited degrees of freedom to move so that the study of the self-reconfigurable theory becomes more and more complex and difficult in the process of self-reconfiguration. Before starting their self-reconfiguration, robots take configuration matching that searches the most common topology between initial configuration and goal configuration, and thus self-reconfigurable efficiency can be improved and complexity can be reduced. The problem is how to carry out configration matching. In order to solve the problem, this paper proposes a self-reconfigurable configuration matching strategy based on the graded optimization mechanism.The first step is to search the common connection between matching scheme and goal configuration. The second step, whose objective function is constructed by configuration connectivity, is to search common topology according to the results of the first step. By setting two optimization objectives mentioned above, the process of configuration matching is simplified. The matching algorithm is tested by the genetic algorithm and the result shows that it is feasible.


Analysis and modeling of the GPS dynamic position error


XU Kun1;HE Yu-yao2;YAN Mao-de2

J4. 2008, 35(4):  749-753. 

Abstract ( 1879 )   PDF (655KB) ( 1483 )   Save

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In order to improve GPS dynamic position precision, the model of the GPS dynamic position error is presented by using time series analysis. The stationarity of error series is verified through inverse serial verification firstly. The error series can be described as AR(10) based on the fact that the auto correlation function is tail-dragged and that the partial correlation is tail-truncated. The parameters are calculated using moment estimation. Adaptive verification proves that the dynamic position error can be presented by AR(10). Applying the model to filter the output data of the GPS receiver with 60km／h, experimental results show the mean square error can be deduced about 27％.


Analysis of the radiation characteristic of the airborn communication antenna


GAO Jun;CAO Xiang-yu;LIU Tao

J4. 2008, 35(4):  754-758. 

Abstract ( 2358 )   PDF (1402KB) ( 1419 )   Save

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The Uniform Geometrical Theory of Diffraction (UTD) is presented to analyze an airborne antenna radiation pattern. The method for setting the scatter model of an aircraft is put forward. The computation formula for the radiation field of the airborne communication antenna in the shadow region is carefully investigated. The computer program of the radiation pattern of an airborne communication antenna is designed. The airborne antenna radiation pattern can be computed rapidly and accurately. Taking the dipole antenna as an example, the radiation pattern of the antenna in different locations on the airborne surface is computed. The results presented in this paper can be used to study the optimization of the airborne antenna disposition.


Fast algorithm for determining the linear complexity of sequences over GF(p^m) with the period kn


DAI Xiao-ping;ZHOU Jian-qin

J4. 2008, 35(4):  759-763. 

Abstract ( 2138 )   PDF (469KB) ( 978 )   Save

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A fast algorithm is presented for determining the linear complexity and the minimal polynomial of sequences over GF(p^m) with the period kn, where p is a prime, gcd(n, p^m-1)=1, p^m-1=kt, and n, k and t are integers. The algorithm presented here covers the algorithm proposed by Chen Hao for determining the linear complexity of sequences over GF(p^m) with the period 3n, where p is a prime, gcd(n, p^m-1)=1, p-1=3t, and n and t are integers. Combining the proposed algorithm with some known algorithms, the linear complexity of sequences over GF(p^m) with the period kn can be determined more efficiently. Finally, an example for applying this algorithm is presented.


Efficient non-parametric GKNN independent component analysis algorithm


WANG Fa-song1;3;LI Hong-wei1;LI Rui2

J4. 2008, 35(4):  764-768. 

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The non-parametric density estimation—generalized k-nearest neighbor(GKNN) estimation based novel independent component analysis(ICA) algorithm which is fully blind to the sources is proposed using a linear ICA neural network. The proposed GKNN density estimation is directly evaluated from the original data samples, so it solves the important problem in ICA and blind source separation(BSS): how to choose nonlinear functions as the probability density function(PDF) estimation of the sources. Moreover, the GKNN-ICA algorithm can separate the hybrid mixtures of source signals which include Gaussian, super-Gaussian, sub-Gaussian, and symmetric distribution ones using only a flexible model and it is completely blind to the sources. The algorithm presented in this paper provides the way for wider applications of ICA methods to real world signal processing. Simulations confirm the effectiveness of the proposed algorithm.