共查询到18条相似文献，搜索用时 72 毫秒
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讨论2类双结构矩阵特征值问题的向后误差公式和上下界。这2类结构矩阵分别是反对称正交阵和反对称反Hamilton阵。使用的主要技术是基于正交辛相似变换。所得结果可看作Tisseur提出的2个待解决问题的回答。 相似文献
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本文研究一类反对称特征值问题在实扰动情形下的向后误差。该问题的系数矩阵同时具有反对称性和零块结构。本文将给出范数型双结构向后误差的表达式,并将所得结果与一般的反对称结构向后误差进行比较。数值实验结果表明,双结构向后误差和反对称结构向后误差的比值有时会非常大。 相似文献
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Tisseur(2000)研究了非齐次多项式特征值问题的条件数，所得结果的不足是对无穷特征值必须另外处理；Declieu和Tisseur(2003)运用微分几何方法研究了齐次多项式特征值问题的条件数，所得结果的不足之处是与系数矩阵的尺度化(scaling)有关。这两种条件数都有各自的应用范围。本文基于投影尺度引入齐次多项式特征值问题的条件数，其优点是与系数矩阵的尺度化无关，因而也许会有较广泛的应用。 相似文献
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水声信号的一种非线性降噪方法 总被引：1，自引：0，他引：1
采用基于非线性动力学系统的局部投影非线性降噪理论,研究了水声信号的非线性降噪问题,并对传统的局部投影算法进行了改进.采用自适应调整邻域大小的方法,改善了传统局部投影算法的邻域选择问题;利用局部投影算法中局部协方差矩阵存在特征值突变的现象,有效地解决了信号子空间和噪声子空间的划分难题.以Henon混沌时间序列为仿真模型,对传统的局部投影算法,以及改进后的算法的降噪性能进行了验证比较,结果表明,改进后的算法更加有效地抑制了噪声. 相似文献
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基于氨基酸的物理化学性质,将氨基酸分为4类,疏水,带电荷,有极性,甘氨酸,在此基础上给出DNA序列一种新的图形表示方法:将1列DNA序列表示为二维空间中的3条特征曲线,利用计算C(i,j)矩阵的主特征值,给出DNA序列的3维特征向量,得到相似距离矩阵.最后计算10种不同物种β-球蛋白第一段外显子的欧式空间距离矩阵D(i,j),并利用UPGMA算法给出了这10种不同物种基于这种相似关系的系统发生树. 相似文献
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针对海上溢油SAR图像中油膜与类油膜的识别问题,提出了一种结合傅立叶分形与特征提取的检测算法。由于分形特征可以具有无穷多的细节,并在不同的研究尺度存在自仿射特性。这与油膜及类油膜表面的几何形貌特征非常吻合。该算法通过计算样本的傅立叶分形特征,组成油膜与类油膜的特征空间。然后,应用基于差分进化的特征选取方法将利于分类的重要特征值筛选出来。再利用重要特征值对原有样本进行分类。实验表明,经特征选取的分形特征向量能够以100%的准确率将两类样本区分开。该算法在选取重要特征的同时实现了对高维特征空间降维的目的,该思想可以应用于其他的基于高维特征的识别系统中,具有普遍的适用性。 相似文献
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本文用有限元素法求解近海水域谐波响应的特征值问题。这是一个广义特征值问题,文中引入固体力学中聚缩质量矩阵的概念和方法,对问题进行简化,计算了两个算例,同理论值及实验值相比较,结果良好. 相似文献
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用一种新方法研究了三对角方程组及对称三对角方程组计算解的最佳向后扰动分析。由于这两类方程组的系数矩阵具有特殊结构 ,因而本文结果不能从已有结果直接导出。所用方法亦可用于研究 KKT及 SQD等结构线性系统的最佳向后扰动分析。 相似文献
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Two kinds of the empirical orthogonal function analysis method for decomposing the mean-field are developed and a comparison is made between them. It is proved that the mean-field can be decomposed using eigenvectors obtained from anomaly-field decomposition, and that more information can be obtained. An example of sea bottom mean temperature analysis shows its remarhabk effect in depicting the distribution features of variousfactors, such as cold water mass, currents and radiation.A few problems concerning the efficiency of the method are discussedand two matrices of relationship which represent the space-time characteristics of the field are derived. The formulae of space-time transformation are obtained conveniently. 相似文献
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Two kinds of the empirical orthogonal function analysis method for decomposing the mean-field are developed and a comparison is made between them. It is proved that the mean-field can be decomposed using eigenvectors obtained from anomaly-field decomposition, and that more information can be obtained. An example of sea bottom mean temperature analysis shows its remarkable effect in depicting the distribution features of various factors, such as cold water mass, currents and radiation.A few problems concerning the efficiency of the method are discussed and two matrices of relationship which represent the space-time characteristics of the field are derived. The formulae of space-time transformation are obtained conveniently. 相似文献
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本文探讨了经验正交分解的基本原理,对两种平均场分解方法进行了比较,结果表明,利用距平场分解得到的特征向量作为基底分解平均场是可行的,文中给出的实例清楚地显示出几个主要影响因子的分布特征。 文中还讨论了几个与经验正交分解法的有效性有关的理论问题,并定义了两种关系矩阵,通过分析它们之间的关系,间接地导出了时空转换公式。 相似文献
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Signal detection is a critical stage in the implementation of any effective communications system. The underwater acoustic environment, particularly in the presence of underwater vehicles, presents significant challenges to reliable detection without excessive false alarms. While there is often sufficient signal-to-noise ratio with respect to stationary broad-band background noise to permit reliable operation, the presence of strong event-like interference signals such as narrow-band signals and impulsive broad-band signals complicates the detection problem significantly. Frequency-hopped signals interleaved with quiescent bands are proposed as the basis of a robust detection system. These signals also make robust detection possible in a multi-access communications system. Two new detection algorithms that exploit the particular structure of these frequency-hopped signals are developed and their performance is analyzed. This analysis uses a modification of the doubly noncentral F-distribution that has not been used previously for such analysis. This distribution makes possible the direct calculation of probabilities of detection and false-alarm under interference and signal scenarios that cannot be analyzed using the better known noncentral F-distribution. With this analysis, the two developed detectors are shown to offer superior performance to that of either the CFAR detector or the binary data sequence detector. Experimental data confirms the theoretically derived results 相似文献
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端元提取是混合像元分解的基础,也是高光谱遥感的研究热点。对于特定区域的高光谱图像应该使用哪种端元提取算法,需要对各种端元提取算法进行客观地评价。作者针对黄河口湿地CHRIS高光谱图像,使用了重建图像与原图像的均方根误差、有效端元数量两个指数对PPI、N-FINDR、VCA、OSP、IEA和SISAL六种典型的端元提取算法进行了评价。结果表明,SISAL算法重建误差最小,仅有其他算法误差的10%~28%;OSP算法识别了具有物理意义的6种有效端元,多于其他算法识别的地物类型,而SISAL算法识别的端元缺乏物理意义。 相似文献
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This paper proposes an improved version of Unscented Kalman Filter (UKF), namely Robust Adaptive UKF (RAUKF), with a special focus on Bearings-Only Target Tracking for three-dimensional case (3DBOT). The automatic tuning of the noise covariance matrices and the robust estimation of the target states form a critical point for the performance of the Kalman-type filtering algorithms, especially in the variable environmental conditions exposed in underwater. The key idea of the proposed filter is to combine robust aspects of UKF and adaption of the process and measurement noise covariance matrices with low computational complexity. The main contribution of this paper is to adjust these matrices by means of the steepest descent algorithm, and the H∞ technique is embedded to achieve superior performance in terms of accuracy and robustness against initial conditions and model uncertainties. Different experiments are performed to evaluate the performance of the proposed algorithm in the 3DBOT problem with a single moving observer. Simulations demonstrate that the proposed filter produce more accurate results with satisfactory computational burden in comparison with other methods. 相似文献
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Shape classification of the 40-Hz waveforms obtained by the recently launched AltiKa satellite has been attempted in the paper. Since retracking algorithms suitable for altimeter return echoes based on Brown model are not applicable for the echoes from coastal ocean, specific algorithms are to be devised for such echoes. In the coastal ocean, waveforms display a wide variety of shapes due to varying coastline geometry, and topography. Hence, a proper classification strategy is required for classifying the waveforms into various categories so that suitable retracker could be applied to each category for retrieving the oceanic parameters. The algorithm consists of three steps: feature selection, linear discriminant analysis, and Bayesian classifier. The classification algorithm has been applied to the waveforms in the close proximity of Gujarat coast. Independent validation has been done near the eastern coast of India. Confusion matrices obtained for both the coasts are quite encouraging. Individual examples of classification have been provided for the purpose of illustration. 相似文献