最优化问题算法重用研究

为提高算法设计的效率以及缩小设计所需的时间,提出了算法重用的思想,即通过解决同一类型问题的算法框架来生成具体算法。并以N皇后问题的回溯算法为实例,介绍了算法设计过程。通过算法重用,文中可在解决这类问题的算法框架下,根据自身选择的实现函数,在框架下填充算法的具体细节,从而避免了算法设计的重复性工作,节省了设计所需的时间,提高了设计效率。     

A fast algorithm for optimal linear interpolation

A fast algorithm for computing the optimal linear interpolation filter is developed. The algorithm is based on the Sherman-Morrison inversion formula for symmetric matrices. The relationship between the derived algorithm and the Levinson algorithm is illustrated. It is shown that the new algorithm, in comparison with the well-known algorithms, requires fewer multiplications and hence is of lower complexity     

An Adaptive Algorithm for Motion Compensated Color Image Coding

This paper presents an adaptive algorithm for motion compensated color image coding. The algorithm can be used for video teleconferencing or broadcast signals. Activity segmentation is used to reduce the bit rate and a variable stage search is conducted to save computations. The adaptive algorithm is compared with the nonadaptive algorithm and it is shown that with approximately 60 percent savings in computing the motion vector and 33 percent additional compression, the performance of the adaptive algorithm is similar to the nonadaptive algorithm. The adaptive algorithm results also show improvement of up to 1 bit/pel over interframe DPCM coding with nonuniform quantization. The test pictures used for this study were recorded directly from broadcast video in color.     

Schur algorithms for Hermitian Toeplitz, and Hankel matrices withsingular leading principal submatrices

It is shown how a simple matrix algebra procedure can be used to induce Schur-type algorithms for the solution of certain Toeplitz and Hankel linear systems of equations when given Levinson-Durbin algorithms for such problems. The algorithm of P. Delsarte et al. (1985) for Hermitian Toeplitz matrices in the singular case is used to induce a Schur algorithm for such matrices. An algorithm due to G. Heinig and K. Rost (1984) for Hankel matrices in the singular case is used to induce a Schur algorithm for such matrices. The Berlekamp-Massey algorithm is viewed as a kind of Levinson-Durbin algorithm and so is used to induce a Schur algorithm for the minimal partial realization problem. The Schur algorithm for Hermitian Toeplitz matrices in the singular case is shown to be amenable to implementation on a linearly connected parallel processor array of the sort considered by Kung and Hu (1983), and in fact generalizes their result to the singular case     

一种快速的图像小目标检测算法

针对图像小目标检测问题进行了研究,在分析现有研究成果的基础上,充分利用了遗传算法动态多点搜索的快速性,以及分形特征应用于目标检测的稳定性,提出一种基于遗传算法与分形特征的快速图像小目标检测算法,并对算法进行了仿真。仿真结果表明该算法有效地提高了图像小目标检测的速度。     

基于改进的群搜索算法求解分类规则

本文阐述了求解分类规则的改进群搜索算法,该算法是基于群搜索算法实现的。群搜索算法是一种新的群体智能优化算法,适宜求解多模态高维问题。对群搜索算法进行了简单的改进,加入了对算法中个体位置的边界值限制,以提高收敛速度。通过实验表明,此算法在求解分类规则中取得了良好的实验结果。     

Locally optimal soft handoff algorithms

The design of soft handoff algorithms for cellular radio systems is considered. The design problem is posed as a tradeoff between three metrics: the rate of handoffs, the mean size of the active set, and the link quality. It is argued that the algorithm that optimizes the tradeoff among these metrics is impractical. Hence, a locally optimal (LO) handoff algorithm is derived as a practical approximation to the optimal handoff algorithm. The LO algorithm is shown to yield a significantly better tradeoff than the static threshold handoff algorithm used in second-generation code-division multiple-access (CDMA) systems. It is also shown that the dynamic threshold algorithm, which is an ad hoc algorithm proposed for third-generation CDMA systems, achieves nearly the same performance as the LO algorithm. Thus, an analytical justification is developed for the dynamic threshold algorithm. Further, the handoff algorithm design is separated into independent design problems on the forward and reverse links. The forward link LO algorithm is shown to be computationally intensive but is also shown to be closely approximated by the simpler reverse link LO algorithm.     

基于改进BP算法的机载双基地SAR成像

首先建立了机栽双基地SAR的几何模型、距离历程和回波模型。接着简要总结了双基地SAR成像的算法思路。通过理论推导改进了单基地BP成像算法使其适合于双基地情况,并探讨了改进的快速BP算法。最后用点目标和面目标仿真验证了双基地下BP算法的有效性和适用性,并与RD算法进行了性能的比较。     

Pseudo-maximum-likelihood data estimation algorithm and itsapplication over band-limited channels

A pseudo-maximum-likelihood data estimation (PML) algorithm for discrete channels with finite memory in additive white Gaussian noise environment is developed. Unlike the traditional methods that utilize the Viterbi algorithm (VA) for data sequence estimation, the PML algorithm offers an alternative solution to the problem. The simplified PML algorithm is introduced to reduce the computational complexity of the PML algorithm for channels with long impulse response. The adaptive version of the PML algorithm suitable for time-varying channels such as frequency-selective Rayleigh fading channels is also introduced. Computer simulation results demonstrate the performance of these algorithms and compare them to the VA-based techniques for different types of channels. The performance design criterion for the PML algorithm is derived in the Appendix     

频率选择性衰落信道中V-BLAST系统的改进概率译码算法

该文结合双向M-BCJR算法,提出了一种用于频率选择性信道条件下的V-BLAST系统的改进迭代译码算法。该算法通过改进度量函数与引入Kullback-Leibler距离计算进行双向搜索的方法,在保持算法低复杂度的基础上,提高了算法性能。仿真结果验证了该算法的性能。     

基于克隆粒子群算法的图像分割方法

最大熵阈值法是目前图像分割中应用最广泛的方法之一。为了快速准确地自动确定图像分割阈值,把克隆选择算法和粒子群算法相结合,提出克隆粒子群优化算法。利用这种改进方法对最大熵图像分割函数进行全局寻优。克隆选择算法和粒子群算法的结合克服了各自的缺点,克隆选择的多样性补偿了粒子群的多样性差的缺点,粒子群的快速性补偿了克隆选择的收敛速度慢的缺点。克隆粒子群方法克服了传统遗传算法易出现早熟、陷入局部最优等的问题,加快了图像分割函数收敛速度,最后能够快速准确地得到图像分割的最佳阈值。实验表明,改进后的算法分割速度较快,易于收敛到最优解,并且得到的分割阈值更加稳定。     

The /spl alpha/-EM algorithm: surrogate likelihood maximization using /spl alpha/-logarithmic information measures

A new likelihood maximization algorithm called the /spl alpha/-EM algorithm (/spl alpha/-expectation-maximization algorithm) is presented. This algorithm outperforms the traditional or logarithmic EM algorithm in terms of convergence speed for an appropriate range of the design parameter /spl alpha/. The log-EM algorithm is a special case corresponding to /spl alpha/=-1. The main idea behind the /spl alpha/-EM algorithm is to search for an effective surrogate function or a minorizer for the maximization of the observed data's likelihood ratio. The surrogate function adopted in this paper is based upon the /spl alpha/-logarithm which is related to the convex divergence. The convergence speed of the /spl alpha/-EM algorithm is theoretically analyzed through /spl alpha/-dependent update matrices and illustrated by numerical simulations. Finally, general guidelines for using the /spl alpha/-logarithmic methods are given. The choice of alternative surrogate functions is also discussed.     

一种多传感器融合的多维数据互联算法

多传感器融合的数据关联问题一直是目标跟踪领域的核心与难点之一.文中提出了一种多传感器融合的多维数据互联算法.首先进行多目标跟踪模式的判断,根据跟踪模式选取不同维数的数据互联算法,对现有的多维数据互联算法存在问题进行了分析和改进,给出了算法实现的伪代码.仿真与实验结果表明,该算法对弹道目标跟踪具有较好的效果,对复杂环境下的多目标也能进行稳定地跟踪.     

一种新的重频分选检测门限选择算法

在小波理论的基础上提出了一种新的重频分选检测门限选择算法，并在此基础上对原有的重频分选算法给予改进。原有的重频分选算法检测门限选择单一，不适用于脉冲列分布不均匀的信号环境，该算法克服了这些缺点，不仅适用于脉冲列分布均匀的情况，而且适用于脉冲列分布不均匀的情况。仿真结果表明该算法较传统的CDIF算法对固定PRI形式的雷达脉冲列的分选有较好的效果。     

Face detection and tracking using a Boosted Adaptive Particle Filter

A novel algorithm, termed a Boosted Adaptive Particle Filter (BAPF), for integrated face detection and face tracking is proposed. The proposed algorithm is based on the synthesis of an adaptive particle filtering algorithm and the AdaBoost face detection algorithm. An Adaptive Particle Filter (APF), based on a new sampling technique, is proposed. The APF is shown to yield more accurate estimates of the proposal distribution and the posterior distribution than the standard Particle Filter thus enabling more accurate tracking in video sequences. In the proposed BAPF algorithm, the AdaBoost algorithm is used to detect faces in input image frames, whereas the APF algorithm is designed to track faces in video sequences. The proposed BAPF algorithm is employed for face detection, face verification, and face tracking in video sequences. Experimental results show that the proposed BAPF algorithm provides a means for robust face detection and accurate face tracking under various tracking scenarios.     

Fast subsampled-updating stabilized fast transversal filter (FSUSFTF) RLS algorithm for adaptive filtering

We present a new, doubly fast algorithm for recursive least-squares (RLS) adaptive filtering that uses displacement structure and subsampled-updating. The fast subsampled-updating stabilized fast transversal filter (FSU SFTF) algorithm is mathematically equivalent to the classical fast transversal filter (FTF) algorithm. The FTF algorithm exploits the shift invariance that is present in the RLS adaptation of an FIR filter. The FTF algorithm is in essence the application of a rotation matrix to a set of filters and in that respect resembles the Levinson (1947) algorithm. In the subsampled-updating approach, we accumulate the rotation matrices over some time interval before applying them to the filters. It turns out that the successive rotation matrices themselves can be obtained from a Schur-type algorithm that, once properly initialized, does not require inner products. The various convolutions that appear In the algorithm are done using the fast Fourier transform (FFT). The resulting algorithm is doubly fast since it exploits FTF and FFTs. The roundoff error propagation in the FSU SFTF algorithm is identical to that in the SFTF algorithm: a numerically stabilized version of the classical FTF algorithm. The roundoff error generation, on the other hand, seems somewhat smaller. For relatively long filters, the computational complexity of the new algorithm is smaller than that of the well-known LMS algorithm, rendering it especially suitable for applications such as acoustic echo cancellation     

Mixed-Radix Algorithm for the Computation of Forward and Inverse MDCTs

The modified discrete cosine transform (MDCT) and inverse MDCT (IMDCT) are two of the most computationally intensive operations in MPEG audio coding standards. A new mixed-radix algorithm for efficiently computing the MDCT/IMDCT is presented. The proposed mixed-radix MDCT algorithm is composed of two recursive algorithms. The first algorithm, called the radix-2 decimation-in-frequency algorithm, is obtained by decomposing an N-point MDCT into two MDCTs with the length N/2. The second algorithm, called the radix-3 decimation-in-time algorithm, is obtained by decomposing an N -point MDCT into three MDCTs with the length N/3. Since the proposed MDCT algorithm is also expressed in the form of a simple sparse matrix factorization, the corresponding IMDCT algorithm can be easily derived by simply transposing the matrix factorization. Comparison of the proposed algorithm with some existing ones shows that our proposed algorithm is more suitable for parallel implementation and particularly suitable for the layer III of MPEG-1 and MPEG-2 audio encoding and decoding. Moreover, the proposed algorithm can be easily extended to the multidimensional case by using the vector-radix method.     

基于富里哀变换的带限信号外推算法

本文提出一种直接基于富里哀变换的带限信号外推新算法: FFT迭代算法。它在外推性能和谱估值方面比以往的方法好。由于采用了FFT和收敛加速因子,它是一种实用的算法。数值例子表明,对有噪声数据而言,FFT迭代算法是一种有效的外推算法。     

基于VB和Access的温度采集系统的设计与实现

针对函数优化问题,提出了一种基于离差平方和法的粒子群优化算法。该算法用混沌序列初始化粒子的位置和速度,选择好于粒子群优化算法产生的粒子位置。通过离差平方和法进行聚类,利用分类方式来更新粒子的速度。最后将算法应用到3个典型的函数优化问题中,数值结果比较表明,提高了算法搜索能力,全局最优解的精度和收敛速度。     

A contention resolution algorithm for input-buffered batcher-banyan networks

A simple algorithm for resolving output contentions in an input-buffered Batcher-banyan network is described. The basic idea in this algorithm is to let the binary nodes of the Batcher network participate in the arbitration process. The proposed algorithm is completely distributed and parallel; thus it scales well to large size switches. Furthermore, our algorithm is fair and requires an overhead that is significantly less than that due to the well-known three-phase algorithm. Two variations of the algorithm are described.