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Table of Content

    20 December 2006 Volume 33 Issue 6
      
    Original Articles
    A scheme for quantum local area networks and performance analysis
    ZHU Chang-hua(1);PEI Chang-xing(2);MA Huai-xin(3);YU Xiao-fei(2)
    J4. 2006, 33(6):  839-843. 
    Abstract ( 2934 )   PDF (192KB) ( 1879 )   Save
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    This paper presents a scheme for Quantum Local Area Networks (QLAN) based on entanglement swapping and classical switching, in which the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol is applied to implement multiple users communication, the message on building and releasing channel, etc. is transferred by the classical switch, and the entanglement of photons between sender and receiver is built by entanglement swapping and quantum information is transferred by the principle of quantum teleportation. Performance analysis results show that the throughput of QLAN increases greatly with higher probabilities with which entanglement is built between sender’s photons and receiver’s photons, the sender finishes the joint Bell state measurement successfully and the receiver detects the sender’s qubit information, respectively.

    An efficient VLSI architecture of the CABAC decoder in H.264
    SHI Ying-bo;LI Yun-song;ZHANG Jian-long
    J4. 2006, 33(6):  844-848. 
    Abstract ( 2849 )   PDF (182KB) ( 1618 )   Save
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    A hardware implementation of the Context-based Adaptive Binary Arithmetic Coding(CABAC) decoder for H.264/AVC is presented. Based on the full use of the parallel architecture, an efficient solution for VLSI implementation is described. By developing the two-level finite state machines to control the decoding process and adopting the memory clear schedule to solve the problem of coefficients storage being time-consuming, the complexity of CABAC-decoder implementation is reduced, and the speed is increased to generate one bit within one or two cycles. Simulation results testify that our design can meet the needs of decoding the H. 264/AVC main profile CIF bit stream at 30fps in real time.

    Hidden authentication conditional oblivious transfer
    ZHAO Chun-ming;GE Jian-hua;LI Xin-guo
    J4. 2006, 33(6):  849-852. 
    Abstract ( 1702 )   PDF (145KB) ( 878 )   Save
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    Hidden authentication conditional oblivious transfer based on oblivious attribute credentials(OACerts) and hidden credentials is proposed and a scheme based on bilinear pairing for implementing the idea is constructed which solves the problem that OACerts may exposure some sensitive information of the receiver. The scheme proposed has the property that only the receiver who has the required attribute credentials can open the message corresponding to its attribute value and that the receiver need not provide to the sender any credentials. The sender can not decide whether or not the receiver can open the messages and which message he can open.

    Sliding mode control for trajectory tracking of the electrically driven cable-supported parallel manipulator
    HUANG Jin;ZI Bin;DUAN Bao-yan
    J4. 2006, 33(6):  853-857. 
    Abstract ( 2512 )   PDF (192KB) ( 1438 )   Save
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    The feed cabin of the next generation large spherical radio telescope is pulled with six long cables, which are driven cooperatively with motors to track radio sources. Similar to a parallel manipulator, the cable-cabin structure can be viewed as a cable-supported parallel manipulator (CPM). Due to the inherent characteristics of nonlinearity, delay and multivariable coupling for this flexible structure, a novel control method combining sliding mode control (SMC) with fuzzy logic control is developed to realize trajectory tracking of the feed cabin, in which SMC parameters can be adjusted with fuzzy logic in real time. At the same time the exponent approximating control is added by grading. This approach not only increases the respond speed and improves the robustness of the control system, but also weakens its chattering. Simulation results show the effectiveness of the proposed method.

    An image watermarking algorithm in the 2-D cepstrum domain based on a pseudo-random sequence watermark
    ZHANG Min-rui(1;2);LU Chen-hong(1);YI Ke-chu(1)
    J4. 2006, 33(6):  858-861. 
    Abstract ( 2010 )   PDF (186KB) ( 981 )   Save
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    Digital watermarking can provide copyright protection and authentication to the owners or users of multimedia. The two major popular algorithms are in the space domain and transform domain. In order to further improve the robustness of the image watermarking algorithms, a 2-dimensional cepstrum transform is introduced in image watermarking algorithms and a novel image watermarking scheme in the cepstrum domain is proposed in this paper. A pseudo random sequence is used as the watermark and is embedded into the host image in its 2-dimensional cepstrum domain. The embedded watermark can be detected without the original image. Extensive computer simulation results show that the proposed algorithm meets the imperceptibness and is robust to a few kinds of watermarking attack, such as JPEG compression, additive and multiplicative noise, filtering and some other image processing operations.

    Study of AlGaN/GaN HEMT high temperature anneal in N2
    WANG Chong;ZHANG Jin-feng;HAO Yue;FENG Qian;YANG Yan;ZHANG Jin-cheng
    J4. 2006, 33(6):  862-865. 
    Abstract ( 2187 )   PDF (178KB) ( 888 )   Save
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    Annealing experiments were carried out at 200~600℃ for 1min and 5min on many batches of AlGaN/GaN HEMTs on the sapphire, and the DC characteristics before annealing and after cooling were compared and analyzed. Also measured were the change of the characteristics of the ohmic contacts and the schottky contacts. It is found that the optimized annealing condition for improving the device characteristics is 500℃ annealing for 5min. Under this condition the maximum transconductance is raised by 8. 9%, the reverse leakage of schottky gate is reduced by two orders of magnitude, and the threshold voltage moves toward the positive direction. The elevation of the schottky barrier height after annealing causes the reduction of gate leakage and the more depletion of channel electrons, which also leads to the change of the saturation current and the threshold voltage. The surface morphology of the schottky contact is observed after annealing by SEM. No obvious change is found for 500℃-annealed samples, but bubbling appears for 600℃-annealed ones.
    A new buffering and scheduling policy for data bursts at core nodes of OBS networks
    GUO Yan-tao;WEN Ai-jun; LIU Zeng-ji;WU Dan-fang
    J4. 2006, 33(6):  866-870. 
    Abstract ( 2246 )   PDF (206KB) ( 931 )   Save
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    The paper proposes a new buffering and scheduling policy for data bursts (DBs) with fiber delay lines (FDL) , which is set at core nodes according to a specific configuration. The main idea is that when competing at a core node, the low-priority class data burst (DB) is buffered with FDL in order to forward the high-priority DB as early as possible, and the reserved wavelength channel for the low-priority DB will be re-assigned to the contending high-priority DB by sending a new burst control packet (BCP) , called the second BCP signaling, from the node to the downstream nodes. The effects of network traffic loads, the average length of DBs and the size of FDL buffer on DB’s loss probability and end-to-end delay are studied by an OBS network system simulation. Results show that the proposed scheduling policy can reduce obviously the DB loss probability and end-to-end delay for high-priority class DB. So it can improve significantly the end-to-end QoS for high-priority DBs.
    An infrared feature and image similarity-based image fusion method
    YANG Cui;ZHANG Jian-qi
    J4. 2006, 33(6):  871-875. 
    Abstract ( 2012 )   PDF (169KB) ( 1046 )   Save
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    An infrared feature and image similarity-based image fusion scheme, which combines aspects of feature-level fusion with pixel-level fusion, is proposed to improve the computing speed and the quality of the fused image, thus making it easier for the observer to interpret the scene. In the proposed scheme, the infrared image is segmented based on the infrared features of the targets, and the target regions and the background are fused respectively; in the fusion process of the target regions, the image structural similarity is used to measure the similarity between the corresponding target regions in the source images, on the basis of which different fusion rules are applied to the redundant and complementary/conflicting regions. Compared with some commonly used multiresolution image fusion methods, the scheme presented is much faster, with an improved fusion effect, which is due to the full use of the infrared features of the infrared image and the detailed information of the visible image.
    Field experimental determination of TOD criteria
    WANG Xiao-rui(1);ZHANG Jian-qi(1);LI Zhao-hui(2)
    J4. 2006, 33(6):  876-880. 
    Abstract ( 1595 )   PDF (178KB) ( 853 )   Save
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    Triangle orientation discrimination threshold (TOD) criteria are determined utilizing the field experimental data. The discrimination probability of the tank and triangle pattern in various ranges is given by the statistical method, respectively using the forced-choice experimental method based on their field measured image. Further, the Weibull function is fitted to the discrimination probability data by the least-square deviation method, and the TOD criteria corresponding to 75% correct discrimination probability are determined. A comparison with John’s criteria and TOD criteria provided by TNO shows that this method can determine a reasonable evaluation value for the TOD criteria.
    The correction of geometric distortion for along-track motion compensation
    LI Yan-ping;XING Meng-dao;BAO Zheng
    J4. 2006, 33(6):  881-886. 
    Abstract ( 2066 )   PDF (211KB) ( 863 )   Save
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    A loss of geometric accuracy of SAR images will occur after the along-track motion compensation. As a result, the sub-image connection and the multi-band image fusion will become difficult. In this paper, the expression of the geometric distortion after the along-track motion compensation is derived. Then a method is presented for geometric distortion correction. Firstly, the along-track motion error is compensated by applying the phase compensation function. Secondly, the position and the position shift of the target are determined according to the Doppler rate estiamted. Lastly, the SAR image is interpolated. Simulated data real multi-band data are used to validate this method.
    An image automatic registration algorithm for interferometric synthetic aperture radar complex images
    LIU Bao-quan;FENG Da-zheng;WU Nan;LI Jun-xia
    J4. 2006, 33(6):  887-891. 
    Abstract ( 2468 )   PDF (181KB) ( 1333 )   Save
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    An automatic InSAR image registration approach is presented based on the curve feature. The characteristic of this technique is its application of a series of algorithms, such as B-spline curve fitting, Quasi-Newton Method, correlation coefficient and Least square method, to achieve superior accuracy and efficiency. Experimental and comparison results confirm our method’s validity.
    A new cyclic autocorrelation based blind parameter estimation method for PSK signals
    JIN Yan;JI Hong-bing
    J4. 2006, 33(6):  892-895. 
    Abstract ( 2105 )   PDF (149KB) ( 1060 )   Save
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    The cyclic autocorrelation function for PSK signals is derived, a cyclic autocorrelation based statistic is established, and by employing such a statistic a new blind parameter estimation method for PSK signals is proposed. This cyclic autocorrelation based method is computationally efficient and easy to realize due to the utilization of FFT (Fast Fourier Transform) in calculating the one-dimensional slices of cyclic autocorrelation function. Moreover, this estimation approach avoids multi-dimensional search and it applies to low signal-to-noise cases. Simulation experiments are provided for evaluating the parameter estimation performance, and experimental results have proved the validity of the method.
    Sparse hidden space support vector machine
    WANG Ling(1);BO Lie-feng(1);LIU Fang(2);JIAO Li-cheng(1)
    J4. 2006, 33(6):  896-901. 
    Abstract ( 2824 )   PDF (151KB) ( 882 )   Save
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    In this paper, (1,3)L11(1,3) norm is employed to loose the bound of the VC dimension, and thus a new structure risk based on the (1,3)L11(1,3) norm is developed. Utilizing this structure risk in the hidden space, we propose a sparse hidden space support vector machine (SHSSVM). Attributing to the merit of the (1,3)L11(1,3) norm, a good sparsity is achieved by the SHSSVM. Like the hidden space support vector machine (HSSVM), the kernel functions used in the SHSSVM are not required to satisfy the Mercer condition, so they can be chosen from a wide range. Simulations on artificial and benchmark data sets for regression and classification prove that the SHSSVM has as good generalization performance as the support vector machine (SVM), and better than the HSSVM. Furthermore, the SHSSVM obtains a sparser decision function than SVM and HSSVM, thus increasing the speed of function evaluation.
    A LTS-HD measure based robust registration approach to low SNR images
    LAI Rui(1;2);LIU Shang-qian(2);ANG Yin-tang(1);LI Yue-jin(1)
    J4. 2006, 33(6):  902-906. 
    Abstract ( 1875 )   PDF (209KB) ( 915 )   Save
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    Since inherent noise of image sensors influences the precision and reliability of numerous existing image registration algorithms severely, a robust registration approach to low SNR images is presented. By using the technique of the regional multi-direction gray difference threshold to extract feature points, and then adopting least trimmed square Hausdorff distance(LTS-HD) measure based point set matching method to acquire parameters of the affine transform, the algorithm realizes the registration of images to be registered. Experimental results indicate that the method has the preferable adaptability for noise disturbance and scene change.
    Distributive passive radar imaging algorithm based on multiple external illuminators
    WANG Sen-gen;WANG Jun
    J4. 2006, 33(6):  907-910. 
    Abstract ( 1905 )   PDF (144KB) ( 1017 )   Save
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    An imaging algorithm based on the two-dimensional Fourier transform is proposed for target imaging in a new type of passive radar system which uses multiple non-cooperative external illuminators as transmitters. In this algorithm the target scattering function could be reconstructed from the echo data via coordinate conversion, two-dimensional interpolation and two-dimensional Fourier transform. We select two circumstances for computer simulation: 12 TV station signals are available when the target rotated 30 degrees and 10 TV station signals were available when the target rotated 11 degrees, respectively. Simulation results show the effectiveness of the proposed algorithm.
    Investigation of the source-side thermal breakdown mechanism in the deep submicron technology GGNMOSFET under ESD conditions
    ZHU Zhi-wei;HAO Yue;FANG Jian-ping;LIU Hong-xia
    J4. 2006, 33(6):  911-916. 
    Abstract ( 1702 )   PDF (235KB) ( 855 )   Save
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    Based on the investigation of the deep-submicron silicided GGNMOSFET under ESD stress, a current crowding model at the edge of source/drain contact is presented, which includes the impact of parasitic series resistance. The model indicates that current crowding can be found in the front edge of the source/drain contact because of different device temperatures and doping concentrations of the diffusion, so a new hot spot starts to develop in the source and the thermal breakdown characteristics of the source/drain are affected at the same time. The source-side thermal breakdown mechanism of the devices can be explained well by this model.
    Inverse halftoning based on the median pyramid
    KONG Yue-ping(1;2);ENG Ping(1);ZHENG Hai-hong(1);XU Pei-pei(1)
    J4. 2006, 33(6):  917-921. 
    Abstract ( 1719 )   PDF (279KB) ( 763 )   Save
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    Focused on the property of error diffuse halftoning, a multi-scale pyramid transform for two dimensions is constructed by the nonlinear median operator. Using the transform distribution of halftone noise in approximations and details on each-scale and its de-noising method are studied through many experiments, and a novel inverse halftoning algorithm via median pyramid transform is proposed. The method firstly decomposes the halftoning image by the transform in one-scale, and a wiener filter is applied to the detail coefficients. Then an inverse image is reconstructed from the cleaned details and approximations. Experimental results demonstrate that the proposed transform can separate the halftone noise and details better than the linear multi-scale transform. The proposed algorithm has the efficient edge preserving ability while smoothing the halftone patterns, excellent PSNR performance, low time complexity and small memory requirement.
    A high saturation mapping algorithm using the gamut partition and variant anchor
    LIU Rui-hua;WANG Yi-feng;ZENG Ping
    J4. 2006, 33(6):  922-924. 
    Abstract ( 1517 )   PDF (138KB) ( 755 )   Save
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    A high saturation algorithm for gamut mapping with a minimized color difference is presented. The color space is partitioned into 5 subareas by studying the relationship between saturation of mapping and geometric characteristics of the destination gamut. In each subarea, a different mapping strategy is selected to improve the saturation and precision of colors after mapping. Particularly, a method of variant anchor is used in the subarea which contains the maximum chroma point to ensure the color continuity of the mapping result. Experimental results show that the algorithm greatly enhances the saturation and precision of color reproduction, and significantly improves the quality of the color image output.
    Optimized biorthogonal wavelets design method for image compression
    SONG Bei-bei;XU Lu-ping
    J4. 2006, 33(6):  925-930. 
    Abstract ( 1951 )   PDF (295KB) ( 1502 )   Save
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    An optimized biorthogonal wavelets design method is presented to meet the various demands for image compression for wavelet bases. First, a design rule for single-parameter biorthogonal wavelets is described, which helps to balance the regularity and filter length of wavelet filters, and thus improves their frequency characteristics. Then a single-parameter evaluation function is established by regulating the coding gain and unbalanced metric of space-frequency resolution. By maximizing the constructed function, the optimized biorthogonal wavelets for image compression can be obtained. Experiments show that the algorithm is easy to realize, only with the self-correlation of the interested image needed. A higher PSNR is obtained compared with other wavelets of the same category.
    A new timing and frequency synchronization method for OFDM systems
    SUN Xian-pu;JIN Hua-feng;WANG Yue
    J4. 2006, 33(6):  931-934. 
    Abstract ( 2470 )   PDF (144KB) ( 1464 )   Save
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    A novel timing and frequency synchronization algorithm is proposed for orthogonal frequency division multiplexing (OFDM) systems requiring only one training symbol. Based on the analysis of the conventional methods, the proposed algorithm redesigns a modified training symbol which is weighted by the pseudo-noise (PN) sequence in a new manner. This algorithm can improve the synchronization performance greatly. Simulation results show that the proposed algorithm not only possesses better timing synchronization performance than the conventional method, but also ensures a higher accuracy of frequency synchronization estimation even in the multipath fading channel.
    Public-key traitor tracing based on the bilinear map
    Lü Xi-xiang(1);YANG Bo(2);PEI Chang-xing(1)
    J4. 2006, 33(6):  935-938. 
    Abstract ( 2059 )   PDF (151KB) ( 953 )   Save
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    A new traitor tracing scheme is proposed by using the Weil pairing in elliptic curves. The proposed scheme shows that the Weil pairing enables us to add a global escrow capability to the traitor tracing system. A single escrow key enables the decryption of ciphertexts encrypted under any public key,which is essential for the system manager to manage the global situation. The authorities can also supervise the entire market and forbid the spread of bad information with the global escrow capability. In addition, with the same security, this scheme, whose operations are on elliptic curves, is more efficient than the previous schemes based on the discrete-log problem over the group (1,3)G(1,3).
    An encryption scheme based on DNA
    LU Ming-xin(1;2);CHEN Yuan(1;2);QIN Lei(3);XIAO Guo-zhen(1;2)
    J4. 2006, 33(6):  939-942. 
    Abstract ( 1927 )   PDF (189KB) ( 912 )   Save
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    Using the technologies of DNA synthesis, DNA clone, PCR and DNA chip and the theory of computational complexity, an encryption scheme is formed. In the scheme, encryption is to confect a specially designed DNA mixture and decryption is the hybridization of DNA sequances on a DNA chip (microarray). Thousands of billions of DNA probes are hybridized and identified according to the Watson-Crick complementarity on a DNA chip simultaneously. The great potential of DNA in vast parallelism computation and extraordinary information density is shown in this scheme to some degree. The limitations of current DNA technology and computational technology are the double guarantee for this scheme.
    A digital rights management system suitable for IPTV
    LI Xin-guo(1;2);GE Jian-hua(1);FENG Li-min(1);GUO Hui(1)
    J4. 2006, 33(6):  943-948. 
    Abstract ( 1495 )   PDF (190KB) ( 794 )   Save
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    A digital rights management system is presented to prevent the pirates from pirating the digital content of IPTV. The schemes for realizing the key modules of the system such as video files encryption/decryption at the servers terminal and licenses acquiring/operating at the clients terminal are also proposed. The system is designed to be very concise by employing the license mechanism both in the content encryption server and in the clients. The secret data of the clients like private keys and operation logs are stored and operated in the inner of the smartcard, by which our system gets its characteristic of higher security.
    Efficient proof of a committed number lying in a specific interval
    ZHANG Jing-liang(1;2);MA Li-zhen(3);WANG Yu-min(1)
    J4. 2006, 33(6):  949-952. 
    Abstract ( 1832 )   PDF (161KB) ( 872 )   Save
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    The existing protocols that are used to prove that a committed number (1,3)x(1,3) lies in a specific interval (1,3)[a,b](1,3) mostly prove that the integer (1,3)x(1,3) is no less than (1,3)a(1,3) and then repeat the same method to prove that (1,3)b(1,3) is no less than (1,3)x(1,3). In order to delete the repetition in these methods a new protocol is proposed by integrating the protocol that two committed numbers are equal with the protocol of the CFT proof. A verifier can be convinced that the committed number (1,3)x(1,3) is neither less than the integer a nor more than the integer (1,3)b(1,3) after the protocol is operated only once, and hence the exact proof that (1,3)x(1,3) lies in the interval (1,3)[a, b](1,3) is achieved. The proposed protocol is a statistical zero-knowledge proof. In contrast to Boudot’s protocol, our method reduces an exponentiation operation; the communication quantity decreases from 16176 bits to 13222 bits, and the communication efficiency increases by 18. 26 percent.
    Security analysis and improvement of several partial blind signature schemes
    XIN Xiang-jun(1;2);LI Fa-gen(3);XIAO Guo-zhen(1)
    J4. 2006, 33(6):  953-955. 
    Abstract ( 2704 )   PDF (111KB) ( 1460 )   Save
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    The security of several partial blind signature schemes based on the discrete logarithm proposed recently by Zhang et al. is analyzed, and it is found that the adversary can get rid of the partial blind property of the signature without being detected by multiplying the reverse of the partial blind factor to the blind message, and the adversary can forge the embedding parameter in the signature. Then, by using the factoring difficulty and covering the order of the generator of the finite field, the improved partial blind signature schemes not only have the partial blind property but also can withstand the forgery of the embedding parameter, and at the same time they have the same other security requirements as those of the schemes by Zhang et al.
    AR routing algorithm for the extensible resource reservation duration
    SHEN Yu-long(1;2);PEI Qing-qi(2);MA Jian-feng(1;2)
    J4. 2006, 33(6):  956-959. 
    Abstract ( 1869 )   PDF (164KB) ( 849 )   Save
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    This paper proposes a model of the AR extensible resource reservation duration and a method for computing the AR request extension loss rate of different QoS levels. This algorithm overcomes the problem that the current AR application needs to declare its starting time and duration of resource reservation in advance. Based on the model of the AR extensible resource reservation duration, the AR request extension loss rate is introduced in the link cost function, and the AR routing protocol of the extensible resource reservation duration is presented. Simulation results show that this routing algorithm increases the success rate of the AR request extension, has a better resource use rate and makes more AR applications with an unpredictable lifetime successfully extend resource reservation duration.
    Full-wave analysis of slot antennas fed by the microstrip using MoM
    LEI Juan;FU Guang;YANG Lin;FU De-min
    J4. 2006, 33(6):  960-964. 
    Abstract ( 1536 )   PDF (212KB) ( 832 )   Save
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    An effective numerical method is presented for modeling slot antennas fed by the microstrip. The equivalence principle is applied so that an original problem can be divided into two isolated equivalence problems. With the discrete complex images method (DCIM) and RWG basis functions, we can give a full-wave analysis of equivalence problems in the spatial domain without the Sommerfeld integrals. These closed-form Green’s functions account for all radiation, surface-wave, and mutual-coupling effects. Triangular facets are used so that our method is suitable for analyzing a complex structure. Numerical results of two typical examples are given which validate this method.
    Exploring the group secure communication model of CSCW in the P2P network
    MA Yong(1;2);TIAN Yu-min(1)
    J4. 2006, 33(6):  965-969. 
    Abstract ( 1573 )   PDF (228KB) ( 811 )   Save
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    A group secure communication model of CSCW in the P2P network is proposed, which permits users to join and quit the system dynamically and freely, and provides secure, warranted and ordered communication between peers. User management and peer communication supply the necessary support for CSCW applications in the P2P network. Theoretical analysis can prove the persistence between the different peers in the group, and collaborative draw is used as an example to express the factual effect.
    Time delay units quantization error analysis and wideband phased array digital beamforming
    CAO Yun-he(1);SHANG Hai-yan(1);ZHANG Shou-hong(1);WANG Sheng-hua(2)
    J4. 2006, 33(6):  970-974. 
    Abstract ( 1955 )   PDF (185KB) ( 1149 )   Save
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    Analog time delay units (TDUs) are usually used for wideband phased array beamforming, but quantization error and high cost restrict their applications. This paper analyses first the fact that TDUs quantization error will reduce signal power and range resolution, and then a new wideband digital beamforming method using subarrays and linear frequency modulation(LFM) signal is proposed. The algorithm, which implements the stretch processing and narrowband filtering technique, achieves digital beamforming by weighting inter-subarrays in the time domain. Lowpass filtering limits the bandwidth of the signal prior to digitization and signal processing, reducing the required speed of subsequent digitization and the computing burden. Finally, computer simulatioins demonstrate that digital beamforming eliminates the effect of quantization error and has better performance than the analog TDUs method.
    Optimization and design of the center-fed cage antenna
    ZHOU Bin;LIU Qi-zhong;XU Zhi;JI Yi-cai
    J4. 2006, 33(6):  975-979. 
    Abstract ( 2821 )   PDF (227KB) ( 2147 )   Save
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    The center-fed cage antenna is optimized and designed. The electrical characteristics of the antenna, such as VSWR and Gain, are analyzed by Numerical electromagnetics code, version 2. Then the structure of the antenna and the matching network can be optimized by the Genetic Algorithm (GA), with the gain as the object function and a fitness function formed. The characteristics of VSWR are improved to be less than 3.0, and the gain are greater than 0.0 dB over the 100~400MHz frequency band. Finally a practical antenna is produced, with the calculated data in good agreement with the experimental data.
    A denoising model using the total variation and wavelet method
    LI Min;FENG Xiang-chu
    J4. 2006, 33(6):  980-984. 
    Abstract ( 2506 )   PDF (365KB) ( 1211 )   Save
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    A novel variational denoising model is obtained by replacing the (1,3)H<sup>-</sup>1(1,3)-norm by norms of wavelet coefficients in the OSV model. The associated Euler-Lagrange equation leads to a nonlinear partial differential equation of second order in the wavelet domain. And we also prove the existence theorem of minimizer for the new model by means of Poincare’s inequality and the lower semi-continuity of bounded variation functions. Numerical experiments show that the proposed model not only improves the denoising performance significantly, but also can preserve the appealing visual quality of images.
    Piecewise generalized H2 dynamic output feedback control for discrete-time piecewise systems
    LI Jun-min(1);LI Jiang-rong(2)
    J4. 2006, 33(6):  985-989. 
    Abstract ( 1725 )   PDF (174KB) ( 911 )   Save
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    A generalized H2 controller designed for discrete-time piecewise systems is presented based on a piecewise Lyapunov function. The basic idea of the proposed approach is to construct a dynamic output feedback controller that can be used to establish global stability with generalized H2 performance for the resulting closed-loop system. A sufficient condition of global stability with generalized H2 performance is also given via linear matrix inequality theory.
    Power-optimal encoding of the address bus based on irredundant sorting
    SUN Hai-jun;SHAO Zhi-biao
    J4. 2006, 33(6):  990-994. 
    Abstract ( 1951 )   PDF (187KB) ( 841 )   Save
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    This paper presents a novel low-power address bus encoding method to reduce the transition activity on address buses and hence reduce power dissipation. The irredundant sorting bus encoding method reduces the power dissipation of highly capacitive memory address bus based on the dynamic reordering of the modified offset address bus lines. This method reorders the ten least significant bits of offset address according to the value of offset address, and the optimal sorting pattern is transmitted through the high bits of bus without the need for redundant bus lines. As compared to the conventional encoding methods, the proposed encoding method is superior in terms of transition activity reduction on the address bus. Experimental results by using an instruction set simulator and SPEC2000 benchmarks show that the irredundant sorting bus encoding method can reduce signal transitions on the address bus by 88. 2%, and that the power dissipation of the address bus is reduced by 76. 1%, which indicates that the proposed encoding method is very practical for power optimization of the address bus.
    A modified algorithm for high speed Reed-Solomon decode and its FPGA implementation
    WU Fei(1);WANG Xiao-li(1;2)
    J4. 2006, 33(6):  995-999. 
    Abstract ( 2609 )   PDF (212KB) ( 1508 )   Save
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    Reed-Solomon(RS)codes are forward error correct codes which have been widely used in a variety of communication systems and information storages. This paper modifies the extended Euclidean algorithm first. On the basis of the modified algorithm, we have designed the detailed circuit diagram. We use the pipelined recursive structure to solve the key equation of the decoder, which leads to high performance. And we simulate logically the whole RTL level circuit. We design a pipelined fully parallel multiplier to eliminate the speed bottleneck in the conventional decoder. Based on the new RS decode structure, we design and simulate the decoder at the gate level and implement it by the Xilinx VirtexII XC2V1000. Post simulation shows that our decoder performs better in speed and area of the circuit than traditional decoders.

    A cooperative model for multi-database under the Internet

    MIAO Chun-yu;SHI Mei-lin
    J4. 2006, 33(6):  1000-1004. 
    Abstract ( 1654 )   PDF (183KB) ( 784 )   Save
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    Efficiently and effectively managing the distributed, heterogeneous and autonomous databases under web environment is a key issue for many applications such as grid systems. However, until now no prototype has been applied for databases under web environment without any restriction on local database characteristics, such as data consistency, subsequent control, security control and transaction, etc. In this paper, a data management model named CoDMS is developed to solve this problem. CoDMS is based on computer-supported cooperative work concepts and a data consistency model. Virtual tables are defined to control data consistency, that is, to make it possible to query and/or transfer data without considering local database characteristics. We have also developed a prototype based on CoDMS for web-based database management systems. We shall discuss subsequent security and transaction in the future.