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)]     

A novel auto-reference ultra-wideband receiver scheme

A new auto-reference (AR) transmit-receive scheme and a corresponding group decision algorithm on the generalized likelihood ratio testing (GLRT) principle is proposed in this paper to overcome the drawbacks of the power inefficiency and the high noise vulnerability in transmitted-reference (TR) ultra-wideband (UWB) systems. A partly overlapped detection window structure is introduced in which the decided data frames are regarded as the reference signal so that energy and time resources in the reference frame are saved and full-rate data transmission is achieved. Differential coding was utilized to solve the error propagation problem introduced by the overlapped detection windows. The group decision algorithm on the GLRT principle was utilized to estimate the correlation template through all data frames in detection windows and could offer better noise suppression. Simulation results reveal that the AR scheme with its decision algorithm outperforms the conventional and other modified TR schemes in generalized signal-to-noise ratio (SNR). Translated from Journal Xi’an Jiaotong University, 2006, 40(8): 932–935 [译自: 西安交通大学学报]     

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)]     

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)]     

Novel P-Cycle protection strategy for asymmetric traffic in mesh optical networks

A novel prefigured-cycle (P-Cycle) algorithm was proposed to improve the protection success ratio for asymmetric traffic in mesh optical networks. The proposed algorithm was simulated in a Pan-European COST239 network environment under an asymmetric dynamic traffic model. The experimental results show that the proposed algorithm has lower capacity redundancy and higher utilization rate of configured resources than traditional P-Cycle methods. Network performance can be improved when implementing this algorithm under single-link failure circumstances. The system behavior is analyzed under different traffic volumes and the configuration strategy is also investigated for the heavyload and light-load networks respectively. __________ Translated from Journal of Beijing University of Posts and Telecommunications, 2008, 31(1): (1–4) [译自: 北京邮电大学学报]     

Routing and wavelength assignment in hierarchical WDM networks

A new routing and wavelength assignment method applied in hierarchical wavelength division multiplexing (WDM) networks is proposed. The algorithm is called offline band priority algorithm (offline BPA). The offline BPA targets to maximize the number of waveband paths under the condition of minimum number of wavelengths, and solve the routing and wavelength assignment (RWA) problem with waveband grooming to reduce cost. Based on the circle construction algorithm, waveband priority function is introduced to calculate the RWA problem. Simulation results demonstrate that the proposed algorithm achieves significant cost reduction in WDM network construction. __________ Translated from Journal of Shanghai Jiaotong University, 2007, 41 (5): 747–750 [译自: 上海交通大学学报]     

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)]     

Text clustering based on fusion of ant colony and genetic algorithms

Focusing on the problem that the ant colony algorithm gets into stagnation easily and cannot fully search in solution space, a text clustering approach based on the fusion of the ant colony and genetic algorithms is proposed. The four parameters that influence the performance of the ant colony algorithm are encoded as chromosomes, thereby the fitness function, selection, crossover and mutation operator are designed to find the combination of optimal parameters through a number of iteration, and then it is applied to text clustering. The simulation results show that compared with the classical k-means clustering and the basic ant colony clustering algorithm, the proposed algorithm has better performance and the value of F-Measure is enhanced by 5.69%, 48.60% and 69.60%, respectively, in 3 test datasets. Therefore, it is more suitable for processing a larger dataset. __________ Translated from Journal of Xi’an Jiaotong University, 2007, 41(10): 1146–1150 [译自: 西安交通大学学报]     

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]     

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)]     

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)]     

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)]     

Research on network failure handling technology based on deflection routing

A new deflection routing scheme is proposed to overcome the drawback of existing deflection routing scheme that cannot handle node failure and suffer from routing loops. A new algorithm for computing the backup shortest path tree (SPT) is proposed and a set of procedures are defined for utilizing the backup SPT in case of node or link failure. The failure can be handled swiftly and the backup routes are guaranteed to be loop-free. Experimental results show that the backup routes calculated by proposed scheme are close to the optimal routes by totally re-computing. __________ Translated from Journal of Beijing University of Posts and Telecommunications, 2007, 30(6): 1–4 [译自: 北京邮电大学学报]     

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]     

Analysis of the diffracted current basis functions used in the hybrid MoM-PO method

The combined moment method (MoM)-physical optics (PO) approach proposed by Bilow fails in some cases. Based on the theory of diffraction and the fundamental theory of electromagnetism, Bilow’s diffracted current basis function was modified both within and outside the transition regions. The improved MoM-PO technique is validated by comparison with exact solutions for a right-angled perfectly conducting wedge at normal incidence. Translated from Chinese Journal of Radio Science, 2006, 21(4):514–517 [译自: 电波科学学报]     

Fixed-point blind source separation algorithm based on ICA

This paper introduces the fixed-point learning algorithm based on independent component analysis (ICA); the model and process of this algorithm and simulation results are presented. Kurtosis was adopted as the estimation rule of independence. The results of the experiment show that compared with the traditional ICA algorithm based on random grads, this algorithm has advantages such as fast convergence and no necessity for any dynamic parameter, etc. The algorithm is a highly efficient and reliable method in blind signal separation. __________ Translated from Journal of Taiyuan University of Technology, 2007, 38(1): 35–37 [译自: 太原理工大学学报]     

Topology control based on quantum genetic algorithm in sensor networks

Nowadays, two trends appear in the application of sensor networks in which both multi-service and quality of service (QoS) are supported. In terms of the goal of low energy consumption and high connectivity, the control on topology is crucial. The algorithm of topology control based on quantum genetic algorithm in sensor networks is proposed. An advantage of the quantum genetic algorithm over the conventional genetic algorithm is demonstrated in simulation experiments. The goals of high connectivity and low consumption of energy are reached. Translated from Journal on Communications, 2006, 27(12): 1–5 [译自: 通信学报]     

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)]     

A novel autofocus algorithm based on maximum total variation criteria for SAR images

A novel autofocus algorithm for synthetic aperture radar (SAR) based on total variation is presented in this paper. The method, which starts with a complex phasedegraded SAR image, after the phase errors model is introduced into the range-compressed phase-history domain, carries out phase errors correction by changing the focus till the total variation of the azimuth profile is maximized. Compared with the minimum entropy autofocus algorithm, the autofocus algorithm has less computational complexity and is easier to implement. The simulation and the processing results of the measured data show the validity of the proposed method. Translated from Journal of Xidian University, 2006, 33(2): 167–172 [译自: 西安电子科技大学学报]     

Compression algorithm for electrocardiograms based on sparse decomposition

Sparse decomposition is a new theory in signal processing, with the advantage in that the base (dictionary) used in this theory is over-complete, and can reflect the nature of a signal. Thus, the sparse decomposition of signal can obtain sparse representation, which is very important in data compression. The algorithm of compression based on sparse decomposition is investigated. By training on and learning electrocardiogram (ECG) data in the MITBIH Arrhythmia Database, we constructed an overcomplete dictionary of ECGs. Since the atoms in this dictionary are in accord with the character of ECGs, it is possible that an extensive ECG datum is reconstructed by a few nonzero coefficients and atoms. The proposed compression algorithm can adjust compression ratio according to practical request, and the distortion is low (when the compression ratio is 20:1, the standard error is 5.11%). The experiments prove the feasibility of the proposed compression algorithm. __________ Translated from Chinese Journal of Biomedical Engineering, 2008, 27 (1): 13–17 [译自: 中国生物医学工程学报]