2009 Vol.27

    Please wait a minute...
    For Selected: Toggle Thumbnails
    Uniqueness of Radio Frequency Fingerprint
    YUAN Hong-lin HU Ai-qun;CHEN Kai-zhi
    Journal of Applied Sciences    2009, 27 (1): 1-5.  
    Abstract2223)      PDF(pc) (612KB)(1876)       Save
    Uniqueness of radio frequency fingerprint is the foundation of transmitter recognition based on RF fingerprint. Mathematical model of RF fingerprint recognition system is constructed based on equivalent components having the same effect with overall transmitter components with manufacturing tolerance and drift tolerance. It is shown based on the model that component manufacturing tolerance, drift tolerance and ADC precision are principal influence factors of uniqueness of RF fingerprint. The tolerance-factor is validated in experiments. The results indicate that RF fingerprint is potentially unique.
    Related Articles | Metrics | Comments0
    Cited: Baidu(2)
    Suboptimal Degree Distribution Algorithm of LT Codes of Digital Fountain
    ZHU Hong-peng;ZHANG Geng-xin;XIE Zhi-dong
    Journal of Applied Sciences    2009, 27 (1): 6-11.  
    Abstract2985)      PDF(pc) (561KB)(2622)       Save

    Degree distribution is key to the decoding efficiency of LT codes. With analysis of the variation of preprocessing set, this paper proposes the Optimal Degree Distribution (ODD) of LT codes and analyzes its drawbacks in realization. On the basis of ODD, a practical Suboptimal Degree Distribution (SODD) is put forward. Through testing, with respect to the mean value, the top value and variance of decoding efficiencies, LT codes with SODD perform better than that with Robust Soliton Degree Distribution. The conclusion of research is practically valuable in improving efficiencies of data distribution applications.

    Related Articles | Metrics | Comments0
    Cited: Baidu(18)
    A Game Model of Combination Strategy for Routing Nodes in P2P Networks
    WANG Hao-yun;ZHANG Shun-yi;SUN Yan-fei;LI Jun
    Journal of Applied Sciences    2009, 27 (1): 12-18.  
    Abstract2417)      PDF(pc) (699KB)(1456)       Save
    The existing studies on the game model of P2P nodes do not take into account diversity of nodes types,complexity of node strategies, and asymmetry of node information. This paper presents a game model of combination strategy for routing nodes in P2P networks. In this model, routing nodes are divided into two types, namely good nodes and bad nodes. They are also categorized as end nodes and middle nodes according to their positions in the routing process. The corresponding strategies adopted by each type of nodes at each routing stage are defined as combination strategies of routing nodes. Based on such strategies, this paper analyzes payoff matrixes of the games among various node strategies, and derives transfer conditions of different combination strategies in the game model with asymmetric information and betrayal of routing nodes.
    Related Articles | Metrics | Comments0
    Cited: Baidu(2)
    Modulation Classification Using Weighted Constellation Matching
    ZHANG Lu-ping;WANG Jian-xin
    Journal of Applied Sciences    2009, 27 (1): 19-23.  
    Abstract3161)      PDF(pc) (509KB)(2773)       Save
    Limitation of existing modulation classification based on constellation is studied, and an improved technique proposed. Eleven kinds of signals are divided into three groups with two higher-order moments. Fuzzy C-means clustering is applied to recover the unknown constellations. The recovered constellations are then matched with standard constellations and classified using an improved cost function. Simulation results show that the correct
    identification rate is high even if there are more constellation candidates, with the average recognition rate being improved by more than 25% at SNR of 10 dB.
    Related Articles | Metrics | Comments0
    Cited: Baidu(3)

    Capacity of CDMA and FDMA for Multi-beam GEO Satellite Communications

    HAO Xie-dong;LIU Ai-jun;ZHANG Bang-ning
    Journal of Applied Sciences    2009, 27 (1): 24-28.  
    Abstract2521)      PDF(pc) (711KB)(2539)       Save
    This paper studies capacity of CDMA or FDMA/TDMA for multi-beam geostationary earth orbit (GEO) satellite communication systems. Relation is derived between outage probability of the required SNR and the number
    of users support at a given power control error (PCE) level and voice activity factor. An expression of capacity of multi-beam GEO CDMA system is then obtained. Numerical results show that capacity is sensitive to system
    parameters such as PCE. Using power and continuous phase modulation (CPM), capacity of FDMA/TDMA system is obtained according to the spectral efficiency of CPM. Comparison between CDMA and FDMA/TDMA shows that
    capacity of FDMA/TDMA system is larger than CDMA in multi-beam GEO systems.
    Related Articles | Metrics | Comments0
    Fast Stereo Video Encoding Based on AVS
    WANG Chong ZHAO Li;LUO Lin
    Journal of Applied Sciences    2009, 27 (1): 29-33.  
    Abstract2061)      PDF(pc) (917KB)(1616)       Save
    A new method for fast stereo video encoding based on AVS is presented. In the system, the left-view sequence is encoded by an AVS encoder. For the right-view sequence, combined predictions from the temporal or disparity domains are exploited, with a hierarchical two-stage neural classifier for fast mode decision. The first stage produces different candidates for variable block partitions of each macro-block (MB). The second stage chooses the most suitable prediction sources between forward motion and disparity frames. An improved sum-of-absolutedifferences (SAD) algorithm is proposed in disparity estimation. Experimental results show that the proposed method can achieve time savings up to 80% with negligible quality degradation, and bit-rate increase of only 7%.
    Related Articles | Metrics | Comments0
    Face Feature Extraction and Face Recognition Using Curvelet Transform
    NI Xue;LI Qing-wu;MENG Fan;CAI Yan-mei
    Journal of Applied Sciences    2009, 27 (1): 34-38.  
    Abstract3116)      PDF(pc) (758KB)(2393)       Save
    As the wavelet transform cannot well express curve characteristics of face image, we propose a feature extraction and face recognition method based on curvelet transform. The face image is first decomposed with curvelets.
    Low frequency coefficients are compressed to reduce dimension of feature vectors, and curvelet energy features are calculated in each high frequency subband. The reduced vectors are used to represent features of the face image. Features are then classified using support vector machine. Experimental results on Orl and Yale face databases show that the proposed method is superior to wavelet methods. It is robust to varying illumination conditions, face poses and expressions.
    Related Articles | Metrics | Comments0
    Cited: Baidu(9)
    Multi-view Video Coding with View Scalability Based on Correlation Analysis
    YAN Tao;AN Ping SHEN Li-quan ZHANG Zhao-yang WANG He
    Journal of Applied Sciences    2009, 27 (1): 39-43.  
    Abstract2469)      PDF(pc) (4447KB)(2205)       Save
    To display video on a multitude of different terminals, a multi-view coding scheme with view scalability (SMVC) is proposed. Based on a correlation analysis, all views are divided into two groups: base view and enhancement
    views. The proposed SMVC adjusts characteristics of various multi-view videos. Experimental results show that the scheme can improve coding efficiency and random access capability.
    Related Articles | Metrics | Comments0
    Progressive Image Transmission for Lossless Images Using
    Prior Bitmap
    Chin-chen CHANG Pei-yu LIN;Jun-chou CHUANG
    Journal of Applied Sciences    2009, 27 (1): 44-50.  
    Abstract2008)      PDF(pc) (1825KB)(1298)       Save
    In this paper, we describe a progressive-image-transmission (PIT) scheme based on block-based PIT for lossless images. It is inspired by a previous PIT method presented by Chang et al. Because the original method does not take the significance of each block into consideration, the quality in early stages of decoding is not desirable.To improve it, we propose an enhanced scheme in which a prior bitmap was used to indicate the complexity of each
    block. Based on the prior bitmap, significant information of an image can be transmitted to receiver(s) in early stages of transmission. Experimental results show that the proposed scheme can achieve better results both in PSNR values and in visual quality than other former lossless PIT schemes.

    Related Articles | Metrics | Comments0
    Generalized Running Coding with Prime Base for Efficient Steganographic Embedding
    ZHANG Xin-peng;WANG Shuo-zhong
    Journal of Applied Sciences    2009, 27 (1): 51-55.  
    Abstract2112)      PDF(pc) (488KB)(1296)       Save
    Steganographic coding such as the running coding described in a previous work can be used to improve embedding efficiency, thus enhance steganographic security. In this paper, we modify the original running coding
    method and propose a generalized scheme with a prime base. With the generalized approach, each secret digit in a notational system using a prime base is represented by a series of cover values. Alteration to one cover value is used to embed several secret digits so that distortion is significantly reduced. The previous running coding is in effect a special case of the generalized scheme with a prime base p = 2, i.e., the binary system. Theoretical analysis indicates that the generalized running coding with p = 3 provides the best performance.
    Related Articles | Metrics | Comments0
    Cited: Baidu(6)
    Application of Multi-granularity Color Features in Image Retrieval
    XU Xiang-li;ZHANG Li-biao;YU Zhe-zhou;ZHOU Chun-guang
    Journal of Applied Sciences    2009, 27 (1): 56-61.  
    Abstract2062)      PDF(pc) (1843KB)(1476)       Save
    As the theory of quotient space granularity comput is imported in image retrieval, a novel image retrieval method using multi-granularity color features is proposed. According to different behaviors under different granularities, one can first obtain color features under different granularities, obtaining different quotient spaces. Second, the obtained quotient spaces are combined based on the quotient space granularity combination principle to achieve image retrieval. Compared with other methods using a single color feature, the image retrieval method based on multi-granularity color features utilizes the image’s own information more effectively. Experimental results demonstrate feasibility and validity of the proposed method.
    Related Articles | Metrics | Comments0
    Cited: Baidu(4)
    Classification of Animal Fibers Based on Microscopic Images
    SHI Xian-jun;YU Wei-dong
    Journal of Applied Sciences    2009, 27 (1): 62-66.  
    Abstract2202)      PDF(pc) (662KB)(1961)       Save
    Scale and pattern of cashmere and fine wool are different, which is used as a major reference to distinguish them. A commonly used technique is to analyze cuticle scale edge height (CSH) of fiber from SEM images. However,
    it is expensive and has an average error of 8%. A new method is presented in this paper. After the fiber images are captured with a CCD camera, they are transformed into skeletonzied binary images which are only one pixel
    wide and can show fiber and scale edge details. Four relative shape parameters of the fiber scale are extracted. A multi-parameter Bayes classification model is then developed. Numerical experiment results show that, by using an ordinary microscopy, the proposed Bayes model has the performance similar to that based on a scanning electronic microscopy in differentiating cashmere and fine wool (70 S), with accuracy rate approaching 90%.
    Related Articles | Metrics | Comments0
    Lossless Memory Compression and Efficient Frame Storage Architecture for HDTV Video Decoder
    GAO Hong-li QIAO Fei YANG Hua-zhong;
    Journal of Applied Sciences    2009, 27 (1): 67-74.  
    Abstract2323)      PDF(pc) (611KB)(1384)       Save
    In this work, two schemes are proposed to improve the memory performance in video decoder systems. A novel lossless frame recompression method and an efficient frame storage mapping strategy are employed to reduce the Read/Write and Row Activation operations of the external memory during video decoding processes. Verified with MPEG-2 based HDTV video decoder, the number of bytes writing to the memory is reduced by about 50% in comparison with the conventional decoder using the embedded frame recompression algorithm, without video quality degradation. Moreover, the reading bytes from off-chip memory for motion compensation are not increased. Additionally, by storing the luma and chroma components of one macroblock in one row of different banks, as well as the ten neighboring macroblocks, the logic Row Activation number can be cut down to nearly 5% of the conventional linear storage scheme.

    Related Articles | Metrics | Comments0
    Nonlinear Regularization for Bi-level Image Restoration
    ZHANG Jian-jun;WANG Qin
    Journal of Applied Sciences    2009, 27 (1): 74-78.  
    Abstract2470)      PDF(pc) (1072KB)(1294)       Save
    Restoration of bi-level images is generally performed in two steps, i.e., restoration and thresholding segmentation, which generally does not produce ideal results. This paper proposes a nonlinear regularization method for bi-level image restoration by explicitly using the knowledge of the bi-level image. Unlike the Tikhonov regularization method which eventually results in a linear system of equations, the proposed method leads to a nonlinear optimization problem, solved with the global Barzilai and Borwein gradient method. Simulation results show feasibility and effectiveness of the method.
    Related Articles | Metrics | Comments0
    Cited: Baidu(6)
    Application of Fuzzy-Neural Network to Short-Term Forecast of Electric Power Load
    HU Yue-li;JI Hui-jie
    Journal of Applied Sciences    2009, 27 (1): 79-83.  
    Abstract2241)      PDF(pc) (569KB)(1496)       Save
    Power load forecast is important in energy management with great influence on operation, controlling and planning of electric power systems. Accurate short-term forecast in electric power load can result in cost saving and better operation conditions. Taking into account the complication and uncertainty of short-term load prediction, this paper proposes a short-term load forecast method using fuzzy-neural network (FNN). The FNN model inherits the strong learning ability of neural networks, and has the capability of fuzzy logic for mapping nonlinear functions and extracting similarity from huge historical data. Experiment results show effectiveness of the proposed FNN model. It is applicable to short-term load forecast in power systems with improved performances.
    Related Articles | Metrics | Comments0
    Cited: Baidu(17)
    Cost Optimized Reachability with Probability Bound in Priced Probabilistic Timed Automata
    ZHANG Jun-hua;HUANG Zhi-qiu;CAO Zi-ning;ZHONG Jing
    Journal of Applied Sciences    2009, 27 (1): 84-89.  
    Abstract2388)      PDF(pc) (551KB)(1400)       Save
    This paper solves a reachability problem in priced probabilistic timed automata, which is minimal cost ensuring a probabilistic lower bound. Proper paths that ensure a probability bound in the model are searched. The corresponding priced timed automatons based on these paths are then constructed, and minimal costs obtained. This way, the total minimal cost is naturally obtained. Next, a priced probabilistic timed automaton is extended
    to a multi-priced probabilistic timed automaton with multiple price variables. A similar reachability problem in the extended model can also be solved, which is minimal cost on primary cost while ensuring probabilistic lower bound and with respect to secondary cost upper bounds.
    Related Articles | Metrics | Comments0
    Extracting Web Application Models for Model Verification
    FANG Ming-ke;MIAO Huai-kou
    Journal of Applied Sciences    2009, 27 (1): 90-96.  
    Abstract2610)      PDF(pc) (764KB)(2247)       Save
    For model verification, an approach to extract FSM models of Web applications is proposed. The extraction process is divided into three phases: link extraction, model construction and document generation. By using a regular expression and location technology for tags contained in a tag library built in the lab, information related to links is first extracted from the source codes of Web applications. It is then structured and stored in databases. In model construction, information obtained in the first phase is reconstructed with a mapping and aggregation technology after analyzing elements for model construction such as pages and links within Web applications. Finally, FSM models are obtained to verify the Web applications.
    Related Articles | Metrics | Comments0
    Cited: Baidu(1)
    Gaussian Particle Filter in Integrated Navigation System with a Direct Filter Model
    ZHOU Zhai-he;LIU Jian-ye;LAI Ji-zhou
    Journal of Applied Sciences    2009, 27 (1): 97-101.  
    Abstract2562)      PDF(pc) (626KB)(1825)       Save
    Data fusion of SINS/GPS integrated navigation system is realized using the Gaussian particle filter (GPF) and a direct filtering model. GPF is improved by selecting a suitable important function and a simple algorithmic framework. With parameters of the inertial navigation system (INS) and the GPS pseudo-range, an integrated navigation model is established based on a direct nonlinear filtering method. Implementation is described. Simulation shows that the filtering precision can meet the navigation system’s requirements. Due to the relaxed restriction of the system model and non-Gaussian noise, GPF has advantages in a direct filter system compared to other methods.
    Related Articles | Metrics | Comments0
    Cited: Baidu(9)
    Monitoring Aero-engine Gas Path with Electrostatic Sensors
    WANG Hua;ZUO Hong-fu;WEN Zhen-hua
    Journal of Applied Sciences    2009, 27 (1): 102-105.  
    Abstract3022)      PDF(pc) (598KB)(2572)       Save
    For real time on-line monitoring of components in the gas path of an aero-engine, a gas path condition monitoring method based on electrostatic induction is proposed. The formation mechanism of charged particles in a gas path and the principle of electrostatic sensors are described. Electrostatic sensors are used to monitor the abnormal particles and metal particles in simulation. The result shows that the electrostatic sensor can detect changes in the overall electrostatic charge level due to abnormal particles, indicating availability of the application of electrostatic in gas path monitoring. This provides a basis of developing a technique for airborne aero-engine gas
    path monitoring.
    Related Articles | Metrics | Comments0
    Cited: Baidu(1)
    Error Calibration for Redundancy Collocation of Six MEMS-IMU
    HUANG Hui;LIU Jian-ye;LI Rong-bing
    Journal of Applied Sciences    2009, 27 (1): 106-110.  
    Abstract3075)      PDF(pc) (580KB)(3168)       Save
    System calibration techniques are discussed for strap-down redundant inertial measurement units. The measuring principle and calculation formulation are introduced. A new static calibration approach is discussed for non-orthogonal inertial sensor configuration, with which model parameters can be calculated with high precision. The procedure of parameter calculation and the solution is given. Simulation results show that the new approach can improve navigation precision.
    Related Articles | Metrics | Comments0
    Cited: Baidu(2)
    Detection of Chaotic Direct Sequence Spread Spectrum Signal Based on the Largest Lyapunov Exponent
    XU Wei, GUO Jing-bo
    Journal of Applied Sciences    2009, 27 (2): 111-116.  
    Abstract2094)      PDF(pc) (665KB)(1783)       Save

    Chaotic DS signal is a kind of spread spectrum signal that has the merits of both chaotic and directsequence spread spectrum (DSSS) signals. In order to realize blind detection of chaotic DSSS signal, both conventional
    DSSS signal methods and chaotic signal detection methods are investigated. A novel method is introduced in
    which the C-C method is used to determine key parameters. The largest Lyapunov exponent of time series is then calculated using small data sets. Simulation results verify feasibility of this method under different conditions such as Gaussian noise and multi-path channel.

    Related Articles | Metrics | Comments0
    Cited: Baidu(14)
    Design of LDPC Coder-Decoder Based on Cyclic Shift Matrices
    GUAN Wu, DONG Ming-ke, XIANG Hai-ge
    Journal of Applied Sciences    2009, 27 (2): 117-123.  
    Abstract2327)      PDF(pc) (586KB)(2137)       Save

    In this paper, the LDPC codes used in DVB-S2 and WiMAX are analyzed. A universal structure based on cyclic shift matrices is presented for these codes. A partially parallel decoder is designed with a universal storage
    resource reusing architecture and serial operation processors. This decoder has been implemented on an Altera EP2S60 platform, and can work for 8 064 bit code length at rates 7/8, 6/8, 5/8, 4/8 and 3/8. Test results show that its code throughput can approach 80 Mbit/s.

    Related Articles | Metrics | Comments0
    Cited: Baidu(2)
    Peer-to-Peer Traffic Identification Using Bayesian Networks
    LI Jun1;2, ZHANG Shun-yi1, WANG Hao-yun1, LI Cui-lian2
    Journal of Applied Sciences    2009, 27 (2): 124-130.  
    Abstract2160)      PDF(pc) (688KB)(2341)       Save

    Accurate traffic classification is vital to numerous network activities, such as security monitoring, quality of service provisioning and network planning. However, current P2P applications, which generate a substantial volume of Internet traffic, use dynamic port numbers, HTTP masquerading and payload encryption to avoid detection. In this paper, we present an accurate P2P identification method using Bayesian networks. Based on the abstracted attributes of flow statistics, the optimal attribute subset is selected using genetic algorithms and P2P traffic is identified using Bayesian networks. We evaluate the algorithms and compare them to the previously used Naive Bayesian model and BP perceptron. Experimental results show that the proposed algorithms achieve better overall accuracy up to 95% with less cost. Further, our result indicates that the approaches are capable of identifying unknown P2P traffic and applicable to the real-time applications.

    Related Articles | Metrics | Comments0
    Cited: Baidu(10)
    Orthogonal Constrained PARAFAC Blind Receiver for DS-CDMA Systems
    LIU Xu, HU Zong-Ze
    Journal of Applied Sciences    2009, 27 (2): 131-136.  
    Abstract2065)      PDF(pc) (595KB)(1754)       Save

    A blind detection algorithm for multi-user DS-CDMA systems is presented based on the parallel factor (PARAFAC) model. A novel orthogonal constrained PARAFAC-based blind receiver is proposed, which utilizes
    orthogonality or semi-orthogonality of spreading code in DS-CDMA system. The Cramer-Rao bound (CRB) of the
    orthogonal constrained trilinear decomposition is analyzed. Simulation results show that the orthogonal constrained trilinear alternating least square (OCTALS) algorithm has a lower CRB than traditional trilinear alternating least square (TALS) algorithm in processing DS-CDMA received signals. Compared with the traditional PARAFAC receiver, the OC-PARAFAC receiver has a better BER performance and faster convergence.

    Related Articles | Metrics | Comments0
    Identification of Digital Modulation Signals Based on Cyclic Spectral Density and Statistical Parameters
    ZHU Lei1, CHENG Han-wen1;2, WU Le-nan1
    Journal of Applied Sciences    2009, 27 (2): 137-143.  
    Abstract2678)      PDF(pc) (724KB)(2605)       Save

     A novel method using decision-making theory is proposed to identify digital modulation signals. The method is based on the cyclic spectrum of received signals and the statistical parameters. Using the frequency domain smoothing periodogram to estimate the cyclic spectrum, the characteristic spectral density of digital modulation
    signals is analyzed on the cyclic frequency axis. Statistical parameters of digital modulation signals are then
    extracted. Finally, using the decision-making theory, we present a flow chart and a determination threshold for
    signal recognition by computer simulation. At 5 dB SNR, identification probability of 90% for 2ASK, 4ASK, 2FSK,
    4FSK, 4PSK and 8PSK can be achieved. The results show effectiveness of the method even when signals are buried in strong noise.

    Related Articles | Metrics | Comments0
    Cited: Baidu(15)
    Roaming Subnet Supported Mobile IP Protocol (MIP-RS)
    QIAN Hong-yan, CHEN Bing, QIN Xiao-lin
    Journal of Applied Sciences    2009, 27 (2): 144-149.  
    Abstract1977)      PDF(pc) (707KB)(1448)       Save

    To support a subnet moving in the IPv4 environment, a roaming subnet supported mobile IP protocol (MIP-RS) is proposed by avoiding shortcomings of the mobile IP. In MIP-RS, STA/AP works as a gateway instead of as a MAC device. It is implemented by cooperation between the home agent, the foreign agent, and the intra-domain routing agent. Distance of the node in a mobile subnet from the HA-FA tunnel’s exit can be multi-hops, while it is only one-hop in the mobile IP. A demo system including the special STA/AP was developed to verify MIP-RS. Test results show that MIP-RS can provide high speed data transmission during the subnet moving at the vehicle speed.

    Related Articles | Metrics | Comments0
    Time-Frequency-Space Domain Processing for Radar Detection of Aircraft Wake Vortices
    LI Jun, WANG Xue-song, LIU Yi, WANG Tao
    Journal of Applied Sciences    2009, 27 (2): 150-155.  
    Abstract2090)      PDF(pc) (624KB)(1630)       Save

    In this paper, a signal model representing the time-frequency-space domain characteristics of aircraft wake vortices is established for coherent Doppler radar. The optimal likelihood ratio detector for detection of aircraft
    wake vortices and its quasi-optimal form for large number of pulses and low signal-to-noise ratio (SNR) are derived. The quasi-optimal form is shown to possess the structure of time-frequency-space domain processing and constant false alarm rate (CFAR) property independent of the signal power. Analytical expressions and their approximations for probabilities of detection and false alarm are derived for the quasi-optimal detector. The results indicate that the radar performance of detecting aircraft wake vortices can be effectively improved by using time-frequency-space domain processing.

    Related Articles | Metrics | Comments0
    Cited: Baidu(7)
    Crater Detection from Gray Image of the Moon Surface
    DING Meng1, CAO Yun-feng1;2, WU Qing-xian1
    Journal of Applied Sciences    2009, 27 (2): 156-160.  
    Abstract2690)      PDF(pc) (1162KB)(2589)       Save

    A method for autonomous detection of crater from gray images is proposed. The original image blocks are census-transformed. The obtained histograms are used as feature vectors. Principal component analysis is performed to compress the feature space. Pattern classification is done with support vector machine. Craters of different sizes are detected by reducing and magnifying the crater candidate area. The results show that the proposed method can effectively detect craters of size greater than 20*20.

    Related Articles | Metrics | Comments0
    Cited: Baidu(5)
    Initialization Algorithm for Blind Image Separation Based on Curvelet Sparse Representation
    WANG Jun-hua1, FANG Yong1;2
    Journal of Applied Sciences    2009, 27 (2): 161-166.  
    Abstract2205)      PDF(pc) (2319KB)(1611)       Save

    A new initialization algorithm for blind separation of images is proposed based on curvelet sparse representation. A mixed matrix can be estimated by estimating the center of received signals. This method can
    improve convergence and effectively avoid falling into local minima. Simulation results show that the proposed
    algorithm can achieve better performance for blind source separation of images.

    Related Articles | Metrics | Comments0
    Cited: Baidu(10)
    Accelerating GPU-Based Volume Rendering in Conjunction with Surface Rendering
    GE Jun, SHU Hua-zhong, BAO Xu-dong, LUO Li-min
    Journal of Applied Sciences    2009, 27 (2): 167-171.  
    Abstract2194)      PDF(pc) (1614KB)(2176)       Save

    An improved GPU-based volume rendering method is presented for interactive visualization of image datasets. The closed 3D surface that warps the user-interested datapart is created using a 2D contour-based surface
    rendering algorithm. The 3D surface is then used as proxy geometry for GPU-based ray-casting to achieve fast
    volume rendering. With the rendering of proxy geometry, the number and sampling length of rays are reduced, and the ray-casting time saved. We implement the method on medical and industrial datasets, showing improvement of efficiency without any loss of interested dataparts.

    Related Articles | Metrics | Comments0
    Cited: Baidu(4)
    Novel Sensor System for Measuring Tri-axial Pressure on Foot-Ground Interface
    ZHU Xiang-ming1, YAN Zhuang-zhi1;2, LIU Shu-peng1;2, SI Wen1
    Journal of Applied Sciences    2009, 27 (2): 172-176.  
    Abstract1873)      PDF(pc) (1296KB)(1579)       Save

     This paper presents a new sensor system for measuring the pedaling strength of human foot and the sustenance between the athlete’s tread and the ground. The system consists of a tri-axial pressure sensor, circuits for data acquisition and signal filtering, and data storage and display modules. The sensor is designed and fabricated with a novel mechanical structure using a new piezoelectric material. Based on the nonlinear model of the dual systems of impact machine, a test-bed to simulate the impact on the foot-ground interface is developed to validate the system. The experimental results well agree with the theoretical curve obtained with the nonlinear model dual systems of impact.

    Related Articles | Metrics | Comments0
    Cited: Baidu(11)
    Vertical Tilt Correction for Vehicle License Plate Based on Minimizing Variance of Coordinates of Projection Points
    WU Yi-quan, DING Jian
    Journal of Applied Sciences    2009, 27 (2): 177-181.  
    Abstract2822)      PDF(pc) (669KB)(3233)       Save

    In order to facilitate character segmentation and recognition in a license plate recognition system, the tilting license plates in the located images should be corrected in both the horizontal and vertical directions. A vertical
    tilt correction method by minimizing variance of coordinates of the projection points is proposed. Coarse character segmentation is performed after horizontal correction and upper and lower border delineation. The character points are projected along the vertical direction after shear transform. Two closed-form expressions of the shear angle are derived based on minimizing variance of coordinates of the projection points. Thus the vertical tilt angle is directly determined and the license plate images corrected using the vertical tilt angle. Experimental results show that, compared to the vertical tilt correction methods of the license plate based on rotation projection and line fitting, the proposed method has high accuracy, requires less computation, and is robust. The proposed method has been applied in practical engineering system.

    Related Articles | Metrics | Comments0
    Cited: Baidu(3)
    Wavelet De-noising with Double-Threshold Based on Particle Swarm Optimization
    ZHOU Xian-guo, LI Kai-yu
    Journal of Applied Sciences    2009, 27 (2): 182-186.  
    Abstract1889)      PDF(pc) (644KB)(1259)       Save

    To improve the de-noising performance of filters, we present a new method to optimize the two thresholds based on particle swarm optimization (PSO) in the wavelet domain. Having analyzed the widely used soft threshold and hard threshold de-noising methods, we select the Donoho threshold as the upper threshold, and minimax threshold as the lower threshold. The PSO algorithm is used to optimize the double-threshold for the best threshold for de-noising. Simulation results show that the proposed method can overcome the psuedo-Gibbs phenomenon of the hard-thresholding method and excessive smoothness of the signal caused by soft-thresholding. It enhances SNR and reduces RMSE, providing better performance than the traditional methods.

    Related Articles | Metrics | Comments0
    Ultra-wideband Antenna Design Using Genetic Algorithms
    DING Xiao 1, DING Xuan-hao 2
    Journal of Applied Sciences    2009, 27 (2): 187-191.  
    Abstract2437)      PDF(pc) (713KB)(1959)       Save

    An ultra-wideband microstrip log-periodic antenna (UWB-MLPA) is studied by using genetic algorithms (GA). A multi-object function with low VSWR and high gain is used in the program. The results of GA optimization are compared with traditional methods. An antenna is designed and fabricated, and outdoor measurements carried
    out with good results. The antenna can operate in the L/S band with good electrical and radiation characteristics.
    It is shown that GA is an effective method for this type of UWB antennas.

    Related Articles | Metrics | Comments0
    Cited: Baidu(6)
    Direct Data Domain Approach of Real Weights with Multiple Constraints for Uniform Circular Array
    ZHAO Jun, ZHU Zhao-da
    Journal of Applied Sciences    2009, 27 (2): 192-197.  
    Abstract1901)      PDF(pc) (588KB)(1339)       Save

    In this paper, an improved direct data domain method is studied for airborne radar with uniform circular array antennas in STAP. Based on a single snapshot, this algorithm can effectively restrain jamming and clutter while keeping the signal of interest. By implementing multiple space-time constraints, the system gain is maintained
    when the signal of interest deviates slightly. Experimental results show effectiveness of the method.

    Related Articles | Metrics | Comments0
    Cited: Baidu(1)
    Judgement and Mechanism of Handling on Aperiodic Real-Time Task Overload
    WU Yue, TANG Li-san, YANG Hong-bin
    Journal of Applied Sciences    2009, 27 (2): 198-202.  
    Abstract2140)      PDF(pc) (725KB)(1599)       Save

    A real-time aperiodic task overload handling mechanism based on value of task is presented in this paper. A method of verifying task overload is first presented. A mathematical model termed dynamic constraint knapsack model is established by combining two parameters, deadline and value of task. An enhanced dynamic greed algorithm (EDGA) is then presented to handle the model. By determining parameters and the value function of tasks, performance of EDGA is analyzed in terms of hit value ratio. Experimental results show that EDGA can
    achieve higher hit value ratio compared to the earliest deadline first (EDF), highest value first (HVF) and robust
    highest value first (RHVF) algorithms under all workload conditions.

    Related Articles | Metrics | Comments0
    Parallel Signal Processing for GPS Software Receiver
    MIAO Jian-feng1, SUN Yong-rong1, CHEN Wu2, LIU Jian-ye1, HU Cong-wei3
    Journal of Applied Sciences    2009, 27 (2): 203-209.  
    Abstract2838)      PDF(pc) (1393KB)(3548)       Save

    In view of the inability of real time processing in conventional GPS software receivers, a GPS signal parallel processing algorithm is proposed based on dual core processors. Algorithmic modules in GPS software receivers including signal acquisition, tracking loop and pseudo-range position are analyzed. A parallel processing acquisition algorithm which includes a parallel processing and real-time optimization is studied. In the tracking loop, a separate carrier and CA code phase tracking loop are designed. An optimized bandwidth algorithm is described based on a mathematical analysis, which leads to better dynamic performance and less noise vulnerability of the receiver. The GPS software receiver is validated in computer simulation. Comparison with real testing data shows that the proposed method can improve processing ability at least by 30%, satisfying the requirements of the single point pseudo-range positioning approach.

    Related Articles | Metrics | Comments0
    Cited: Baidu(3)
    Steering Pose Error of the Forklift Robot
    MA Bin-liang1;2, HUANG Yu-mei1, ZHU Cong-min1, YANG Xing-fang1
    Journal of Applied Sciences    2009, 27 (2): 210-215.  
    Abstract1873)      PDF(pc) (569KB)(1418)       Save

    The manipulator’s acceleration and load quality have influence on steering pose of the forklift robot in its operation. Change of acceleration and load quality of the manipulator is transformed into jump of working centroid of the forklift robot. The steering pose error model of the forklift robot is established based on sideslip motion by the coordinate transformation. The effect of acceleration and load quality of the manipulator on steering pose of the forklift robot is analyzed based on the steering pose error model. Analysis shows that change of acceleration and load quality of the manipulator can result in various degrees of understeer and oversteer of the forklift robot.

    Related Articles | Metrics | Comments0
    Cited: Baidu(1)
    Autonomous Constellation Positioning and Timing by Dual-frequency Inter-satellite Measurement
    CAO Hui, XIONG Zhi, YU Feng
    Journal of Applied Sciences    2009, 27 (2): 216-220.  
    Abstract2368)      PDF(pc) (637KB)(1751)       Save

    Traditional autonomous constellation mainly concerns about inter-satellite position measurement. It lacks effective means to overcome the overall constellation rotation. This paper uses a module of inter-satellite measurement with additional parameters including velocity, delay error and clock error, and describes the dispelling ionosphere scattering technique and the method of achieving time and position decoupling. By using GPS, accuracy of LEO satellites in constellation is improved considerably, which offers the entire constellation a fixed time basis simultaneously. Simulation results show that the module with additional parameters has higher accuracy than the traditional module measurement of the entire constellation. Meanwhile, GPS can suppress positioning and clock errors caused by the location error of satellite.

    Related Articles | Metrics | Comments0
    Cited: Baidu(3)
    Call Admission Control in TDD-CDMA-HCS System
    MA Shou-gui, XIE Bo, WANG Jun-bo, CHEN Ming
    Journal of Applied Sciences    2009, 27 (3): 221-225.  
    Abstract2049)      PDF(pc) (613KB)(2077)       Save

    Call admission control based on SINR is proposed to solve the admission problem of TDD-CDMA-HCS (time division duplexing-code division multiple access-hierarchical cell structure) system. Based on the definition of a system utility function, decision of admission is made according to the usage of resources. Both inter-layer call overflow and system-load based layer selection are implemented. Simulation results show that the call block ratio and the system drop-out ratio decrease significantly, resulting in considerable improvement of the system performance.

    Related Articles | Metrics | Comments0
    Cited: Baidu(1)