基于谱间相关性的高光谱图像稀疏分解算法

针对高光谱图像邻近波段相关性强的特点,结合粒子群优化算法的快速寻优能力,提出一种基于谱间相关性的高光谱图像稀疏分解算法.将高光谱图像分组为参考波段图像和普通波段图像,参考波段图像采用粒子群寻优找到最优原子,实现稀疏分解.普通波段图像的最优原子由两部分构成,一部分原子从参考波段图像的最优原子继承而来,继承个数由普通波段图像与参考波段图像的谱间相关性确定,其余原子则由粒子群搜索得到.对高光谱数据集进行稀疏分解,验证算法的分解效率,结果表明,在重构图像精度相当的条件下,稀疏分解速度比正交匹配追踪算法快约18倍.     

On the Meaning of Quantified Maintainability

Maintainability analysis stands today where reliability was ten years ago. Many and varying definitions of maintainability have been proposed; many mathematical approaches to maintainability and its various aspects have been pursued. Nevertheless, there is presently no general agreement on the definition of maintainability or on the technique of its quantification. In addition, there is insufficient meaningful maintainability field and laboratory data. As in the case of reliability, analytical techniques are only a part of the maintainability improvement effort. There is a need for improvement in both the design of the total maintenance system as well as analytical techniques for its evaluation.     

冲激函数和冲激偶函数的物理意义研究

冲激函数和冲激偶函数是信号分析理论中的重要函数,其性质简化了信号分析的过程.本文研究了冲激函数的广义函数定义,分析并解释了冲激函数的取样和筛选性质的物理意义,在此基础上提出了一种冲激偶函数的广义函数定义的物理意义.和传统的定义方式的解释相比,本文提出的解释方式更加易于理解.本文还分析并解释了冲激偶函数的取样和筛选性质的...     

论频谱中负频率成分的物理意义

本文讨论了信号经过傅立叶变换所得频谱的物理意义,其中着重于负频率成分。许多信号与系统的教材中,都认为负频率成分没有物理意义。本文以多方面的实例证明了负频率成分不但具有明确的物理意义,而且有重要的工程应用价值。文章还用Matlab程序演示了如何用几何方法求傅立叶反变换,把集总频谱合成为时域信号,从中也可鲜明地看出负频率成分的意义。     

复费涅耳数的物理意义及其应用

通过对高斯光束经光阑衍射后轴上点光强分布规律的分析,详细讨论了复费涅耳数的物理意义及其应用,指出采用位相片,可将远场轴上光强提高为原高斯光束的几倍以上,而且中央光斑也比高斯光束小,并给出在激光准直中应用的例子。     

On the Decomposition of Two-Dimensional Behaviors

In the paper, a decomposition theorem for autonomous two-dimensional (2D) behaviors, stating that every such behavior can be expressed as the sum of a (uniquely determined) square autonomous behavior and of some finite dimensional autonomous behavior, is introduced. As a result, the well-known decomposition theorem for general complete 2D behaviors EF-PR-SZ can be further investigated, thus leading to a more detailed analysis of the properties of the admissible decompositions.     

Spectral Decomposition of EEG Intervals Using Walsh and Fourier Transforms

This paper presents a comparison of the use of features derived from Walsh and Fourier transforms for classification of short segments of EEG data. The result was that features obtained from Fourier transforms produced consistently better classification results than Walsh function-derived features.     

谱相关的数学关系与物理意义

周期性是自然现象和工程现象的基本特性之一,从复杂多变的、含有噪声的观测数据中发现周期性并测量其参数是信号处理的重要主题.谱相关是分析循环平稳信号二阶周期性的有力工具,本文研究谱相关的周期性解析功能的缘由、过程与特点.首先,梳理了谱相关理论体系中诸多重要概念之间的内在联系,建立了相互之间转换或映射的数学关系图;然后提出了按定义和转换关系逐步求解谱相关的方法.通过单周期信号的分析和每步操作效果与周期的对应关系,诠释了循环自相关、谱相关、无限循环谱和循环频率等重要概念的物理意义.     

晶体管发射极电流集边效应物理意义之探讨

由基区电阻的自偏压引起的晶体管发射极电流集边效应，是限制晶体管承载电流能力的因素之一。     

On the Spectral Density of a Cyclostationary Process

A new approach to the spectral-density concept of a cyclostationary process is presented. This approach is based on the observation that a cyclostationary process can be split into a number of wide-sense stationary subprocesses. The spectral densities of these subprocesses, defined as the Fourier transform of their autocorrelation functions, are nonoverlapping functions of frequency. The sum of the spectral densities of these wide-sense stationary subprocesses yields the well-known expression for the spectral density of a cyclostationary process.     

Fault Detection in Induction Machines Using Power Spectral Density in Wavelet Decomposition

Motor-current-signature analysis has been successfully used in induction machines for fault diagnosis. The method, however, does not always achieve good results when the speed or the load torque is not constant, because this causes variations on the motor-slip and fast Fourier transform problems appear due to a nonstationary signal. This paper proposes a new method for motor fault detection, which analyzes the spectrogram based on a short-time Fourier transform and a further combination of wavelet and power-spectral-density (PSD) techniques, which consume a smaller amount of processing power. The proposed algorithms have been applied to detect broken rotor bars as well as shorted turns. Besides, a merit factor based on PSD is introduced as a novel approach for condition monitoring, and a further implementation of the algorithm is proposed. Theoretical development and experimental results are provided to support the research.     

一种基于小波最佳分解层数的红外光谱基线校正算法

红外光谱分析技术是一种用于食品健康检测、生物制药和环境监测等方面的高新技术。为了去除应用过程中的基线漂移现象,提出了一种基于小波最佳分解尺度的红外光谱基线校正算法。首先,对原始光谱信号多次进行每一层的小波分解,同时也进行每一层的小波重构。然后算得每一层的信噪比,并通过信噪比比对法获得除噪后的光谱信号。接着对该信号进行每一层的小波分解,得到每一层小波细节和小波逼近的频率。分别将两个频率做除法并求出比值。然后比较每层的比值大小,并选择最大的比值作为分解层数的最佳值。将最佳分解层数下的小波逼近系数置零后再进行小波重构,获得基线校正后的光谱信号。通过实验验证发现,该算法不仅可以为小波分解的最佳层数提供依据,而且能够在更好地保留有用信号的同时,除去高频噪声以及低频基线干扰。基线校正比较充分,效果良好。     

On the Spectral Correlation of UWB Impulse Radio Signals

Cyclostationarity is an inherent characteristic of many communication signals, which can be exploited for performing various signal processing tasks. Determining the cyclic statistics of a signal of interest is often necessary in the design of signal processing systems exploiting this cyclostationary behaviour. This work investigates the second order cyclic statistics of various signalling schemes employed in ultra wideband impulse radio systems. Analytical expressions are derived for the cyclic autocorrelation and spectral correlation density functions.     

Analysis and Performance Evaluation of Linear Multiuser Detectors in the Downlink of DS-CDMA Systems Applying Spectral Decomposition

This paper studies the performance of linear multiuser detectors for direct-sequence code division multiple access systems at different loading levels and users' powers, using singular value decomposition (SVD) techniques in the downlink of Rayleigh flat-fading and additive white Gaussian channels. The performance of the matched filter (MF), decorrelator (zero-forcing), and minimum mean-squared error (MMSE) detectors are studied and compared. Analytical and simulation results are also presented in terms of the bit error rate. From this analysis, a simple linear multiuser detector is developed that exploits the structure of the system's spreading codes matrix from the SVD viewpoint. Also, the numerical performance of this proposed detector is compared to that of the conventional detector (MF) as a function of the signal-to-noise ratio. Finally, the performance limits are established in terms of the singular values of the spreading codes matrix. Extensive simulation results validate the analysis presented in the paper for equal or unequal users' powers.     

On the Spectral Skewness of a Narrow-Band Gaussian Process

This correspondence discusses techniques for estimating the spectral skewness of the baseband spectrum of the complex envelope of a narrow-band Gaussian process from its undistorted and distorted (by memoryless nonlinear devices) in-phase and quadrature components. Some applications of the spectral skewness in communication theory are also mentioned.     

On Reliability Evaluation by Network Decomposition

A simple algorithm for evaluating the symbolic terminal-pair reliability of a complex system is presented. The system graph is decomposed into two subgraphs through a minimal cut. The system success is expressed in terms of certain successes of these subgraphs, and then changed into an equivalent disjoint expression which is directly converted on a one-to-one basis into a reliability expression. It yields unusually simple reliability expressions. The algorithm can be computerized but has not been done. Three examples illustrate the algorithm and compare it with other algorithms.     

基于子带分解的自适应滤波

本文对基于子带分解的自适应滤波做了研究，给出子带分解下的包含子带间滤波的最优维纳解和ＬＭＳ算法，并分析了其收敛性能和计算复杂度，与传统的ＬＭＳ算法相比，基于子带分解的自适应滤波具有更好的性能，计算机模拟结果也体现了这一点。