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海平面变化包含多种不同时间尺度信息，传统的预测方法仅对海平面变化趋势项、周期项进行拟合，难以利用海平面变化的不同时间尺度信号，使得预测精度不高。本文基于深度学习的预测模型，提出一种融合小波变换（wavelet transform，WT）与LSTM （long short-term memory，LSTM）神经网络的海平面异常组合预测模型。首先利用小波分解得到反映海平面变化总体趋势的低频分量和刻画主要细节信息的高频分量；然后通过LSTM神经网络对代表不同时间尺度的各个分量预测和重构，实现海平面变化的非线性预测。基于该模型的海平面变化预测的均方根误差、平均绝对误差和相关系数分别为12.76 mm、9.94 mm和0.937，预测精度均优于LSTM和EEMD-LSTM预测模型，WT-LSTM组合模型对区域海平面变化预测具有较好的应用价值。 相似文献
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本文提出一种基于支持向量回归的统计预报方法,通过经验正交分解对原始数据矩阵进行时空分解,提取出空间模态和时间系数。由于海面高度变化具有非线性、大惯性的特点,对时间系数进行小波分析,能有效滤除其中的高频信号,得到表征海面高度变化的低频信号。利用支持向量回归方法对小波分解后的低频信号构建预报模型。最后,进行小波重构,还原时间序列长度,实现未来7天的海面高度预报。通过黑潮附近海域的海面高度预报结果验证,该预报方法的预报效果优于整合滑动平均自回归预报方法。本文通过机器学习的算法实现了海面高度的预报,为海洋预报方法提供了新的思路。 相似文献
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潮位预测严重影响沿海区域，尤其是近海浅水沿岸地区居民的生产生活和涉海活动。谐波分析是长周期潮位预测的传统方法，但无法预测非周期性气象过程发生时的水位变化。与数据处理方法相结合，人工智能的方法通过拟合输入与输出数据的历史数值关系，能够有效预测高度非线性和非平稳的流模式，因而在时间序列数据预测领域得到了广泛的应用。本文结合自适应模糊推理系统（Adaptive Neuro-Fuzzy Inference System, ANFIS）和小波分解方法，利用水位异常和风切变分量作为输入数据，实现了一种综合的多时效潮位预测方法。文中测试了多种输入变量组合和小波-ANFIS（WANFIS）模型，并与人工神经网络（Artificial Neural Network, ANN）、小波-ANN（WANN）和ANFIS模型进行了预测结果对比。通过不同指数的误差分析来看，相比ANN模型，ANFIS模型能够更准确的预测潮位变化，小波分解对ANFIS预测精度有一定的提高，且模型中水位异常和风切变分量数据的加入比单一的潮位数据输入能取得更好的预测结果。 相似文献
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针对水下机器人操纵性优化设计中水动力系数预报问题,在水下机器人水动力预报中引入艇体肥瘦指数概念,确定了水下机器人艇体几何描述的五参数模型。提出采用小波神经网络方法预报水下机器人水动力,确定了神经网络的结构,利用均匀试验设计方法,设计了神经网络的学习样本。研究结果表明,只要确定适当的输入参数,选择适当的学习样本和网络结构,利用小波神经网络方法对水下机器人水动力进行预报可以达到较好的精度。 相似文献
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《海洋地质与第四纪地质》2015,(4)
以北黄海东部坳陷某区块为研究对象,对下白垩统地层通过频谱分解技术进行储层预测和岩性圈闭。该区块是发育在斜坡上的扇三角洲相沉积,砂岩储层薄,地层横向变化大,利用常规的地震属性和地震波阻抗反演难以圈闭有利的储集区域。针对研究区储集层的特点,利用连续小波变换方法,生成调谐体和离散频率能量体,结合地震属性和水平切片技术,实现在频率域进行砂体描述和储层横向变化规律的研究。其预测结果与实际钻井资料吻合得较好,圈定了砂体的分布范围和物源方向,为研究区下一步井位部署提供了依据,也为研究区利用频谱分解方法进行储层预测提供了新的技术方法和手段。 相似文献
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实现地震道零相位化的子波相位谱消去法 总被引：2，自引：0，他引：2
子波相位谱消去法是通过话因式分解并以最大的方差模为准则求得子波相位港,然后将其从地震造的相位谱中消去。与常相住校正方法相比,该方法不要求于波各分频的初相位角为常数。模型实验表明,该方法具有良好的稳定性和对主频变化的适应性,首尾于波的主频相差30Hz时仍能得出很好的结果,这就使得我们对地震道可一次进行全道处理,而不必进行分段处理;对于最小相位地震道及接近最小相位的混合相位地震道,该方法具有较好的容噪能力。对于最大相位地震道及接近最大相让的混合相位地震道,当记录的信噪比较高时也有较好的效果。 相似文献
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为了能够精确地拟合天然水域不规则的水陆边界,并能保持有限差分数值计算在矩形网格中进行,本文利用Thompson的数值网格生成技术,在长江口南支七丫口至横沙河段设计了一个椭圆型边界拟合坐标系,并在这个坐标系下建立了平面二维潮流数学模型。通过数值求解此数学模型,实现了计算区域内现状潮流的一个数值模拟,模拟结果表明,模式的设计是成功的。 相似文献
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Nsiri B. Chonavel T. Boucher J.-M. Nouze H. 《Oceanic Engineering, IEEE Journal of》2007,32(3):729-743
In seismic deconvolution, blind approaches must be considered in situations where reflectivity sequence, source wavelet signal, and noise power level are unknown. In the presence of long source wavelets, strong interference among the reflectors contributions makes the wavelet estimation and deconvolution more complicated. In this paper, we solve this problem in a two-step approach. First, we estimate a moving average (MA) truncated version of the wavelet by means of a stochastic expectation-maximization (SEM) algorithm. Then, we use Prony's method to improve the wavelet estimation accuracy by fitting an autoregressive moving average (ARMA) model with the initial truncated wavelet. Moreover, a solution to the wavelet initialization problem in the SEM algorithm is also proposed. Simulation and real-data experiment results show the significant improvement brought by this approach. 相似文献
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小波变换突破了传统Fourier变换等信号处理方法均限制,具有表征信号局部特征的能力,信号的局部奇异性包含了信号的许多重要信息,论文研究了信号的奇异性检测问题。给出小波变换和信号奇异性的关系,实现小波分析对信号各类奇异间断点的有效检测,最后进行实例分析,说明此理论与方法适用于对边缘信号与突变信号的处理和提取,为海底底质识别提供理论依据。 相似文献
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Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification
Abstract An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-wavelet-convolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm. 相似文献
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Beach profiles have been observed to change over a range of spatial and temporal scales; however techniques for quantifying this variability have not been fully established. In this paper, a wavelet technique is introduced as a method to study the multi-scale variability of beach profiles. The beach profile data comprising a 22-year time series surveyed at the US Army Corps of Civil Engineers Field Research Facility (FRF) at Duck are analysed using the adapted maximal overlap discrete wavelet transform (AMODWT). The analysis successfully identifies strong local features in the variability of beach profiles in time and space separately that cannot be isolated by traditional statistical methods. The analysis of spatial wavelet variances provides a new means of investigating the depth of closure. Analysis of variances by temporal scales shows that the combined effects of several temporal scales with one or two dominant scales can be seen at particular points across profiles whilst the dominant temporal scales are different at different portions of the profiles. The method allows for the extremely nonstationary behaviour of beach profile to be analysed into separate frequency bands that can facilitate the interpretation of morphological changes in terms of physical processes. 相似文献
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本文研究了北太平洋海水表面温度的遥相关型,指出:北太平洋海温有3个遥相关区,分别在西风漂流区、亦道东太平洋区和阿拉斯加湾区。这3个相关区的结构十分类似于大气中的PNA结构。用赤道东太平洋和西风漂流区之间的海温差作为太平洋海温指数PTI,它能代表北太平洋65％海区的海温变化,可以作为太平洋海温场PNA结构的变化指数,用来监视剧Nino和反E1 Nino事件的发生和发展。 相似文献
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A wavelet energy method is presented to search the critical incidence of earthquake excitation in a multi-dimensional seismic response of offshore platforms. The total effective energy and the instantaneous effective energy input rate of an earthquake can be obtained by wavelet transformation to predict the critical incidence of the earthquake and then the maximum dynamic response of the platform can be calculated. The critical incidence is determined using this method for an actual platform and a group of single degree-of-freedom systems. Numerical results show that the application of wavelet transform in a multi-dimensional seismic response of structures is convenient and reliable. 相似文献