A new directional multi resolution ridgelet network

In this paper, we propose a new directional multi-resolution ridgelet network (DMRN) based on the ridgelet frame theory, which uses the ridgelet as the activation function in a hidden layer. For the multi-resolution properties of the ridgelet function in the direction besides scale and position, DMRN has great capabilities in catching essential features of direction-rich data. It proves to be able to approximate any multivariate function in a more stable and efficient way, and optimal in approximating functions with spatial inhomogeneities. Besides, using binary ridgelet frame as the mathematical foundation in its construction, DMRN is more flexible with a simple structure. The construction and the learning algorithm of DMRN are given. Its approximation capacity and approximation rate are also analyzed in detail. Possibilities of applications to regression and recognition are included to demonstrate its superiority to other methods and feasibility in practice. Both theory analysis and simulation results prove its high efficiency. __________ Translated from Journal of Xidian University, 2006, 33(4): 557–562 [译自: 西安电子科技大学学报(自然科学版)]     

Rate control for streaming media transmission over WLAN

In order to solve the problems of link layer retransmission and packet fragment strategies for IEEE 802.11, this paper proposes a variable packet TCPfriendly rate control (VPTFRC) scheme for streaming media transmission over wireless local area network (WLAN) by researching on the policy of packet size adjustment in transport layer based on the minimum retransmit-delay constraint. Unlike other proposals, this process considers the impact of wireless packet error ratio (PER) on the packet size adjustment and the performance of rate control. Simulation results demonstrate that our proposed process can simultaneously achieve higher throughput, better fairness, shorter transmission delay and less jitter than TFRC. Among them, the ratio of delay, jitter and packet loss rate can reach a maximum improvement ratio of 58%, 42% and 85% respectively. __________ Translated from Journal of Huazhong University of Science and Technology (Nature Science Edition), 2007, 35(1): 1–3 [译自: 华中科技大学学报(自然科学版)]     

Blind source separation algorithm for communication complex signals in communication reconnaissance

Most blind source separation algorithms are only applicable to real signals, while in communication reconnaissance processed signals are complex. To solve this problem, a blind source separation algorithm for communication complex signals is deduced, which is obtained by adopting the Kullback-Leibler divergence to measure the signals’ independence. On the other hand, the performance of natural gradient is better than that of stochastic gradient, thus the natural gradient of the cost function is used to optimize the algorithm. According to the conclusion that the signal’s mixing matrix after whitening is orthogonal, we deduce the iterative algorithm by constraining the separating matrix to an orthogonal matrix. Simulation results show that this algorithm can efficiently separate the source signals even in noise circumstances. __________ Translated from Journal of Huazhong University of Science and Technology (Natural Science Edition), 2007, 35(4): 33–36 [译自: 华中科技大学学报(自然科学版)]     

Third-order trajectory planning for high accuracy point-to-point motion

This article studies a third-order trajectory planning method for point-to-point motion. All available instances for third-order trajectory planning are first analyzed. To distinguish those, three criteria are presented relying on trajectory characteristics. Following that, a fast preprocessing approach considering the trajectory as a whole is given based on the criteria constructed and system constraints. Also, the time-optimality of the trajectory is obtained. The relevant formulas are derived with the combination of geometrical symmetry of trajectory and area method. As a result, an accurate algorithm and its implementation procedure are proposed. The experimental results show the effectiveness and precision of the proposed method. The presented algorithm has been applied in semiconductor manufacturing equipment successfully. __________ Translated from Journal of Huazhong University of Science and Technology (Natural Science Edition), 2007, 35(12): 58–61 [译自: 华中科技大学学报 (自然科学版)]     

Research on food-chain algorithm and its parameters

Based on the characteristics of colony emergence of artificial organisms, their dynamic interaction with the environment, and the food-chain crucial to the life system, the rules of local activities of artificial organisms at different levels are defined. The article proposes an artificial life-based algorithm, which is referred to as the food-chain algorithm. This algorithm optimizes computation by simulating the evolution of natural ecosystems and the information processing mechanism of natural organisms. The definition, idea and flow of the algorithm are introduced, and relevant rules on metabolic energy and change in the surroundings where artificial-life individuals live are depicted. Furthermore, key parameters of the algorithm are systematically analyzed. Test results show that the algorithm has quasi-life traits that include being autonomous, evolutionary, and self-adaptive. These traits are highly fit for optimization problems of life-like systems such as the location-allocation problem of a distribution network system. __________ Translated from Journal of Northeastern University (Natural Science), 2007, 28(7): 993–997 [译自: 东北大学学报(自然科学版)]     

A topology control algorithm for preserving minimum-energy paths in wireless ad hoc networks

In this paper, a distributed topology control algorithm is proposed. By adjusting the transmission power of each node, this algorithm constructs a wireless network topology with minimum-energy property, i.e., it preserves a minimum-energy path between every pair of nodes. Moreover, the proposed algorithm can be used in both homogenous and heterogeneous wireless networks, and it can also work without an explicit propagation channel model or the position information of nodes. Simulation results show that the proposed algorithm has advantages over the topology control algorithm based on direct-transmission region in terms of average node degree and power efficiency. Translated from Journal of Xidian University, 2006, 33(3): 341–346 [译自: 西安电子科技大学学报]     

Robust adaptive beamforming algorithm based on Bayesian approach

The performance of adaptive array beamforming algorithms substantially degrades in practice because of a slight mismatch between actual and presumed array responses to the desired signal. A novel robust adaptive beamforming algorithm based on Bayesian approach is therefore proposed. The algorithm responds to the current environment by estimating the direction of arrival (DOA) of the actual signal from observations. Computational complexity of the proposed algorithm can thus be reduced compared with other algorithms since the recursive method is used to obtain inverse matrix. In addition, it has strong robustness to the uncertainty of actual signal DOA and makes the mean output array signal-to-interference-plus-noise ratio (SINR) consistently approach the optimum. Simulation results show that the proposed algorithm is better in performance than conventional adaptive beamforming algorithms. __________ Translated from Journal of Northeastern University (Natural Science), 2007, 28(6): 793–796 [译自: 东北大学学报 (自然科学版)]     

Multi-image gradient-based algorithms for motion measurement using wavelet transform

A multi-image wavelet transform motion estimation algorithm based on gradient methods is presented by using the characteristic of wavelet transform. In this algorithm, the accuracy can be improved greatly using data in many images to measure motions between two images. In combination with the reliability measure for constraints function, the reliable data constraints of the images were decomposed with multi-level simultaneous wavelet transform rather than the traditional coarse-to-fine approach. Compared with conventional methods, this motion measurement algorithm based on multi-level simultaneous wavelet transform avoids propagating errors between the decomposed levels. Experimental simulations show that the implementation of this algorithm is simple, and the measurement accuracy is improved. __________ Translated from Journal of South China University of Technology (Natural Science Edition), 2007, 35(1): 39–43 [译自: 华南理工大学学报(自然科学版)]     

Closed-form solutions to fractional-order linear differential equations

The definitions and properties of widely used fractional-order derivatives are summarized in this paper. The characteristic polynomials of the fractional-order systems are pseudo-polynomials whose powers of the complex variable are non-integers. This kind of systems can be approximated by high-order integer-order systems, and can be analyzed and designed by the sophisticated integer-order systems methodology. A new closed-form algorithm for fractional-order linear differential equations is proposed based on the definitions of fractional-order derivatives, and the effectiveness of the algorithm is illustrated through examples. __________ Translated from Journal of Northeastern University (Natural Science), 2007, 28(1): 10–13 [译自: 东北大学学报(自然科学版)]     

Multiple object detection and tracking with pseudo-particle filter

To tackle the divergence of the classical particle filter method for multiple object tracking in image sequences, a new particle filter, called pseudoparticle filter (PPF), is proposed. The PPF invokes subset particles of generic particle filters to form a continuous estimate of the posterior density function of the objects. After sampling-importance resampling (SIR), the subset particles converge to the observations. It is proved that, using an appropriate kernel function of the mean shift algorithm, we can get the subset particles of the observations and the fixed points of clustering results as the state of the objects. A multiple object data association and state estimation technique is proposed to resolve the subset particles correspondence ambiguities that arise when multiple objects are present. Experimental results demonstrate the efficiency and effectiveness of the algorithm for single and multiple object tracking. __________ Translated from Journal of Xidian University, 2008, 35(2): 248–253 [译自: 西安电子科技大学学报(自然科学版)]     

Indoor and outdoor people detection and shadow suppression by exploiting HSV color information

An adaptive background model based on maximum statistical probability and a shadow suppression scheme for indoor and outdoor people detection by exploiting hue saturation value (HSV) color information is proposed. To obtain the initial background scene, the frequency of R, G, and B component values for each pixel at the same position in the learning sequence are respectively calculated; the R, G, and B component values with the biggest ratios are incorporated to model the initial background. The background maintenance, or the socalled background re-initiation, is also proposed to adapt to scene changes such as illumination changes and scene geometry changes. Moving cast shadows generally exhibit a challenge for accurate moving target detection. Based on the observation that a shadow cast on a background region lowers its brightness but does not change its chromaticity significantly, we address this problem in the article by exploiting HSV color information. In addition, quantitative metrics is introduced to evaluate the algorithm on a benchmark suite of indoor and outdoor video sequences. The experimental results are given to show the performance of the algorithm. __________ Translated from Journal of Huaqiao University (Natural Science), 2007, 28(1): 30–33 [译自: 华侨大学学报 (自然科学版)]     

Medical image lossless compression based on combining an integer wavelet transform with DPCM

To improve the classical lossless compression of low efficiency, a method of image lossless compression with high efficiency is presented. Its theory and the algorithm implementation are introduced. The basic approach of medical image lossless compression is then briefly described. After analyzing and implementing differential plus code modulation (DPCM) in lossless compression, a new method of combining an integer wavelet transform with DPCM to compress medical images is discussed. The analysis and simulation results show that this new method is simpler and useful. Moreover, it has high compression ratio in medical image lossless compression. __________ Translated from Journal of Northeastern University (Natural Science), 2007, 28(10): 1454–1457 [译自 : 东北大学学报 (自然科学版)]     

Fast public-key encryption scheme based on Chinese remainder theorem

Traditional public-key cryptosystems suffer from a relatively low encryption/decryption speed, which hampers their applications in resource-constrained environments. A fast public-key cryptosystem is proposed to remedy this drawback. The new algorithm uses Chinese remainder theorem to hide the trapdoor information. The encryption of the system only carries out several modular multiplication operations, and the decryption only needs a modular multiplication and a low-dimensional matrixvector multiplication, which makes the speed of the encryption and the decryption of the scheme very high. The security of the system is based on two difficult number-theoretic problems. The attacker has to solve the integer factorization problem and the simultaneous Diophantine approximation problem simultaneously to recover the secret key from the public key. The proposed cryptosystem is also shown to be secure against lattice attack. The analysis shows that the encryption algorithm is a secure, fast and efficient public-key cryptosystem. __________ Translated from Journal of Xidian University, 2008, 35(3): 449–454 [译自: 西安电子科技大学学报(自然科学版)]     

Image restoration using total variation and anisotropic diffusion equation

This paper proposes a new model for the image restoration which combines the total variation minimization with the “pure” anisotropic diffusion equation of Alvarez and Morel. According to the introduction of new diffusion term, this model can not only remove noise but also enhance edges and keep their locality. And it can also keep textures and large-scale fine features that are not characterized by edges. Due to these favorable characteristics, the processed images turn much clearer and smoother, meanwhile, their significant details are kept, which results in appealing vision. __________ Translated from Journal of Xidian Universiy, 2006, 33(5): 759–762 [译自: 西安电子科技大学学报 (自学科学版)]     

Differential attack on nonlinear combined sequences

By using the coding properties and statistic properties of the plaintext, the differential properties of the key stream sequences generated by a nonlinear combined generator were analyzed. Then a differential attack algorithm on the nonlinear combined sequences was proposed. At last, an attack example adopting the differential attack algorithm was presented. __________ Translated from Journal of National University of Defense Technology, 2006, 28(4): 78–82 [译自: 国防科技大学学报]     

PRF-ambiguity resolution for SAR by contrast minimization in range-Doppler domain

An algorithm was developed to accurately estimate the Doppler centroid, which is needed for high-quality synthetic aperture radar (SAR) image formation by resolving the SAR pulse repetition frequency (PRF) ambiguity. The algorithm uses the SAR range migration to resolve the PRF-ambiguity by searching for a PRF-ambiguity number that minimizes the intensity contrast in the range-Doppler domain. Experimental results show that the approach, compared with traditional methods for resolving the SAR PRF ambiguity, is more suitable for both high contrast scenes such as urban areas and low contrast scenes such as mountains. Moreover, the approach is more computationally efficient for there are no time-consuming correlations or fast Fourier transform (FFT) operations needed in the range-Doppler domain and only part of the range cells are used in the calculation. Translated from Journal of Tsinghua University (Science and Technology), 2006, 46(7): 1 259–1 261 [译自: 清华大学学报(自然科学版)]     

Analysis on two novel spherical helical antennas

Two novel spherical helical antennas are designed by projecting the planar equiangular spiral antenna onto hemisphere and partial sphere surfaces. Their radiation properties are analyzed by the moment method with curved basis and test function, and the curves of the voltage standing wave ratio (VSWR), gain, polarization and pattern that change with frequency are also given, respectively. It can be seen that the circular polarization band of the novel hemispherical helical antenna is broader. The gain curve of the partial spherical helical antenna is flatter and the structure is simpler. __________ Translated from Journal of Xidian University, 2008, 35(1): 144–147 [译自: 西安电子科技大学学报 (自然科学版)]     

Pattern synthesis of antennas based on a modified particle swarm optimization algorithm

In order to overcome the drawbacks of standard particle swarm optimization (PSO) algorithm, such as prematurity and easily trapping in local optimum, a modified PSO algorithm is proposed, in which special techniques, as global best perturbation and inertia weight jump threshold are adopted. The convergence speed and accuracy of the algorithm are improved. The test by some benchmark problems shows that the proposed algorithm achieves relatively higher performance. Thereafter, the applications of the modified PSO in the radiation pattern synthesis of antenna arrays are presented. __________ Translated from Chinese Journal of Radio Science, 2006, 21(6): 873–878 [译自: 电波科学学报]     

Study and simulation of video communications under wireless environment based on blind source separation

A new scheme is proposed to separate several compressed video signals transferred in multiple wireless channels using the blind source separation method. The scheme selects IEEE 802.11b and XVID compression as the wireless communications channel and MPEG-4 video compression, respectively. A simulation model is then made for the video communications under a wireless environment. The model can separate several video signals using blind source separation. Simulations show that the normalized whiten plus cyclic whiten based on cyclostationary (NWCW-CS) algorithm based upon the cyclostationary characteristics of signals has the best separation performance and fast convergence. Besides, the algorithm can solve the mixing of video signals. The image of the transferred video signals decompressed by XVID is nearly consistent with the source ones. The new method meets the requirement of real-time video communications. __________ Translated from Journal of Southeast University (Natural Science Edition), 2007, 37(1): 13–17 [译自: 东南大学学报(自然科学版)]     

Mass detection algorithm based on support vector machine and relevance feedback

To improve the detection of mass with appearance that borders on the similarity between mass and density tissues in the breast, an support vector machine classifier based on typical features is designed to classify the region of interest (ROI). Furthermore, relevance feedback is introduced to improve the performance of support vector machines. A new mass detection scheme based on the support vector machine and the relevance feedback is proposed. Simulation experiments on mammograms illustrate that the novel support vector machine classifier based on typical features can improve the detection performance of the featureless classifier by 5%, while the introduction of relevance feedback can further improve the detection performance to about 90%. __________ Translated from Journal of Xidian University, 2007, 34(2): 239–245 [译自: 西安电子科技大学学报(自然科学版)]