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采用粒度谱计算方法分析连云港及邻近海域悬沙和表层沉积物交换特征,为徐圩防波堤口门布置和连云港港航道回淤研究提供理论支撑。连云港港主航道和徐圩航道5 m等深线以外的区域悬沙和表层沉积物交换率为0.1~0.2,表明航道回淤强度将处于较低水平,对今后航道维护有利;5 m等深线以内区域的交换率为0.3~0.4,悬沙落淤对航道回淤有一定贡献,表明该航道段回淤量相对较大,计算结果与实测航道回淤强度分布特征基本一致。灌河口沙嘴正常天气条件下交换率小于0.2,说明悬沙落淤对沙嘴的影响较小;5 m等深线以内破波带水域交换率大于0.5,表明悬沙和表层沉积物交换频繁。连云港港及邻近海域悬沙和表层沉积物交换主要为粒径小于62 μm的细颗粒组分。分析结果表明,为减少泥沙回淤对徐圩港区港池正常运行的影响,兴建防浪挡沙堤并将堤头布置在破波带之外十分必要。 相似文献
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Woon Wong 《时间序列分析杂志》1997,18(2):181-194
A stationary multivariate time series { X t } is defined as linear if it can be written in the form X t = ∑∞ j =−∞ A j e t − j where A j are square matrices and e t are independent and identically distributed random vectors. If the e t } are normally distributed, then { X t is a multivariate Gaussian linear process. This paper is concerned with the testing of departures of a vector stationary process from multivariate Gaussianity and linearity using the bispectral approach. First the definition and properties of cumulants of random matrices are used to obtain the expressions for the higher-order cumulant and spectral vectors of a linear vector process as defined above. Then it is shown that linearity of a vector process implies constancy of the modulus square of its normalized higher-order spectra whereas the component of such a vector process does not necessarily have a linear representation. Finally, statistics for the testing of multivariate Gaussianity and linearity are proposed. 相似文献
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Abstract. A symbolic method which can be used to obtain the asymptotic bias and variance coefficients to order O(1/n) for estimators in stationary time series is discussed. Using this method, the large‐sample bias of the Burg estimator in the AR(p) for p = 1, 2, 3 is shown to be equal to that of the least squares estimators in both the known and unknown mean cases. Previous researchers have only been able to obtain simulation results for the Burg estimator's bias because this problem is too intractable without using computer algebra. The asymptotic bias coefficient to O(1/n) of Yule–Walker as well as least squares estimates is also derived in AR(3) models. Our asymptotic results show that for the AR(3), just as in the AR(2), the Yule–Walker estimates have a large bias when the parameters are near the nonstationary boundary. The least squares and Burg estimates are much better in this situation. Simulation results confirm our findings. 相似文献
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PERIODIC CORRELATION IN STRATOSPHERIC OZONE DATA 总被引:1,自引:0,他引:1
Abstract. A 50-year time series of monthly stratospheric ozone readings from Arosa, Switzerland, is analyzed. The time series exhibits the properties of a periodically correlated (PC) random sequence with annual periodicities. Spectral properties of PC random sequences are reviewed and a test to detect periodic correlation is presented. An autoregressive moving-average (ARMA) model with periodically varying coefficients (PARMA) is fitted to the data in two stages. First, a periodic autoregressive model is fitted to the data. This fit yields residuals that are stationary but non-white. Next, a stationary ARMA model is fitted to the residuals and the two models are combined to produce a larger model for the data. The combined model is shown to be a PARMA model and yields residuals that have the correlation properties of white noise. 相似文献
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针对光照变化人脸识别问题中传统的光谱回归算法不能很好地进行特征提取而严重影响识别性能的问题,提出了局部判别嵌入优化光谱回归分类的人脸识别算法。计算出训练样本的特征向量;借助于数据的近邻和分类关系,利用局部判别嵌入算法构建分类问题所需的嵌入,同时学习每种分类的子流形所需的嵌入;利用光谱回归分类算法计算投影矩阵,并利用最近邻分类器完成人脸的识别。在两大人脸数据库扩展YaleB及CMU PIE上的实验验证了该算法的有效性,实验结果表明,相比其他光谱回归算法,该算法取得了更高的识别率、更好的工作特性,并且降低了计算复杂度。 相似文献
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Abstract. In this paper we establish a statistical methodology for the spectral analysis of stationary multivariate time series via the Walsh-Fourier transform. Theoretical results pertaining to the definition and estimation of the Walsh-Fourier spectral matrix and functions of that matrix including cross-spectra, coherency and phase are given. An example of the statistical techniques developed in this paper is given; in particular, the methodologies are applied to neonatal sleep data collected from a study of the effect of maternal substance use during pregnancy. 相似文献