共查询到20条相似文献，搜索用时 46 毫秒
1.
为了揭示地球固体潮中谐波成分间的相关乘性调制关系与非相关叠加关系,并根据这些关系来分析重力固体潮信号中隐含的潮汐谐波。根据地球、月球与太阳旋转轨道的位置关系,建立了一个引潮力的正交分解模型。进一步,基于改进单形进化智能优化算法的独立分量分析的重力固体潮正交分解模型上,利用谱相关方法,对重力固体潮的独立成分进行谱相关分析,从而完整实现了潮汐谐波加性正交分解之后的乘性解调。最后,结合实际观测数据,并引入理论信号作为参考背景,利用以上模型与算法进行对比处理和分析。研究表明,所提出的模型与方法可以有效地实现潮汐谐波的正交分解,凸显能量较弱的长周期谐波分量,并从谱相关图谱中反映潮汐谐波调制关系的变化。 相似文献
2.
The gravity solid tide signal includes daily wave, half-day wave and annual wave and moon wave harmonic component, but the energy of day wave and half-day wave component is relatively strong, and the energy of annual wave and moon wave component is relatively weak. In order to effectively extract these harmonic components with large energy differences and reveal the modulation relationship between them, according to the cause of gravity tide, a gravity solid tide signal decomposition model is used to compare the tidal harmonic components with different strengths. The form of the independent component is decomposed into different orthogonal directions. At the same time, a new optimization algorithm is used to improve the independent component analysis algorithm and separate the independent components of different orthogonal directions. In the spectral correlation analysis of the components of independent components, the autocorrelation operation will make the strong component stronger and the weak component weaker. For this problem, the cross-correlation spectrum between independent components is used to reveal the gravity tide signal., the modulation relationship between harmonic components. The experimental results show that the proposed algorithm not only effectively separates the independent components with large intensity difference in the gravity tide signal from the perspective of additive decomposition, but also reveals the multiplicative modulation relationship between the corresponding tidal harmonics based on the cross-correlation spectrum. 相似文献
3.
Donald H. Eckhardt 《Mathematical Geology》1984,16(2):155-171
Studies of correlation coefficients between different sets of global geophysical data may lead to useful inferences concerning their relationship or independence. If one data set is allowed to rotate with respect to another, the statistical theory is complicated and extra care is required before one can conclude that there is any statistical significance to a maximized correlation coefficient. If, for some relative rotation, two spherical harmonic fields are significantly correlated, then their individual degree component harmonics of dominant power must also be significantly correlated. Rotations can be found that result in high correlations between the dominant low-degree spherical harmonics of the geomagnetic and tertestrial gravity field potentials, but rotations can also be found that result in equally high, yet meaningless, correlations if the lunar gravity field is substituted for the geomagnetic field. To explain such high correlations, the theoretical correlation distribution function between normally distributed component harmonics is derived and then verified for lowdegree harmonics by using a Monte Carlo technique which takes into account the three-dimensional rotation group. Some curious properties surface: (1)the correlation distribution function for all possible relative orientations is almost the same between identical and uncorrelated fields; and (2)a system for determining the correlation distribution function from randomly selected fields or from randomly rotated fields is almost ergodic. 相似文献
4.
The new global gravity models represented by global spherical harmonics like EGM2008 require a high degree and order in their coefficients to resolve the gravity field in local areas; therefore, there are interests to represent the regional or local field by less parameters and to develop a parameter transformation from the global model to a local kind of spherical harmonic model. The authors use local spherical cap harmonics for the regional gravity potential representation related to a local pole and a local spherical coordinate system. This allows to model regional gravity potential with less parameters and less memory requirements in computation and storage. From different kinds of representations of spherical cap harmonics, we have selected the so-called adjusted spherical cap harmonics (ASCH). This is the most appropriate for the presented mathematical model of deriving its coefficients from global gravity models. In that way, the global gravity models can fully be exploited and mapped to regional ASCH, in particular with respect to the computation of regional geoid models with improved solution. 相似文献
5.
G. K. Rangarajan 《Journal of Earth System Science》1994,103(4):439-448
Homogeneous Indian Monsoon region rainfall for the epoch 1871–1990 has been analysed using Singular Spectral Analysis. It
is shown that the HIM time series is simple in structure with only the annual oscillation and its first two harmonics accounting
for almost the entire variability. Longer period oscillations related to lunar tidal forcing, solar activity and quasibiennial
variation are conspicuously absent. It is also shown that the singular spectral decomposition is closely similar to complex
demodulation and thus provides variations in the signals which evolve only slowly with time. As the rainfall series is marked
by several jerky changes, predictability of HIM rainfall through the principal components derived from SSA appears impossible. 相似文献
6.
Laurence C. Breaker William W. Broenkow William E. Watson Young-Heon Jo 《Estuaries and Coasts》2008,31(2):239-257
Elkhorn Slough is a shallow, tidally forced estuary that is directly connected to Monterey Bay. It is ebb-dominated and, due
to continued erosion, the tidal prism has tripled over the past 40 years. Water level measurements at four locations are used
to examine tidal and nontidal oscillations in Elkhorn Slough. The tidal response of Elkhorn Slough differs from that of Monterey
Bay primarily due to the generation of a relatively large number of shallow-water tidal constituents that are due to tidal
distortion caused by friction along the bottom and lateral boundaries, intertidal storage, and nonlinear advection. The shallow-water
constituents range from 3 to almost 15 cycles per day (cpd) and include a rich variety of overtides and compound tides, whose
amplitudes generally increase toward the head of the slough. The tidal harmonics are seasonally dependent, with lower amplitudes
during the fall and winter and higher amplitudes in summer. The tidal constituents were examined using two types of spectral
decomposition, the conventional power spectrum and the more recent Hilbert spectrum. Unlike the power spectrum, the Hilbert
spectrum does not reveal any harmonic structure in the data. Energy associated with tidal distortion in this case appears
to be broadly distributed across the spectral continuum. At least four nontidal oscillations occur in Elkhorn Slough with
frequencies of 26.0, 39.7, 52.7, and 66.9 cpd. The Hilbert spectrum reveals maxima at 26, 39.7, and 66.9 cpd, but not at 52.7 cpd,
suggesting that it is harmonically related to the oscillation at 26.0 cpd. The nontidal oscillations fall into the range of
frequencies associated with the natural oscillations of Monterey Bay. However, evolutionary power spectra indicate that they
appear to be permanent features of the system and thus are not necessarily consistent with seiche-like oscillations that are
often transient and subject to damping. These oscillations could be caused by several factors including edge waves along the
coast of Monterey Bay, long-period surface waves of atmospheric origin that enter the bay from offshore, or breaking internal
waves in and around the Monterey Submarine Canyon. In conclusion, detailed hydrodynamic models are needed to provide a better
understanding of how tidal harmonics are generated and preserved in Elkhorn Slough, and to determine the origin of the natural
oscillations in Monterey Bay. 相似文献
7.
Weak tidal correlation of NW-Bohemia/Vogtland earthquake swarms 总被引：3，自引：0，他引：3
We analyze the possible effect of solid Earth tidal stresses upon a vertical strike-slip fault in NW-Bohemia/Vogtland, central Europe, typical by occurrence of swarm earthquakes. The horizontal components of solid Earth tidal stresses were found strongly to prevail and to reach the level of 2 kPa. We examined tidal triggering as influence of tidal stresses to launching the swarm activity in relative absence of other stress disturbances. The onset times of 46 swarms of mostly ML < 3 earthquakes that occurred in the period 1991–2005 displayed an increased occurrence near the fortnightly maximum of tidal extensive normal stress. The statistical test however did not prove a statistically significant correlation indicating a triggering effect of fault extension due to tidal loading. We also examined tidal effects to the already running seismic activity of the prominent 2000 swarm by comparing the tidal stress distribution in the investigated period with the distribution of tidal stresses in the occurrence times of each earthquake. The results show that these distributions are almost similar, which indicates that individual earthquakes occur independent of tidal stresses. The unclear tidal correlation of the swarm seismicity may be interpreted by small amplitudes and rates of tidal stress changes compared to the amplitudes and rates of coseismic stress perturbations and of pressure bursts of deep generated fluids. 相似文献
8.
9.
我国重力固体潮实验研究进展 总被引：5，自引：2，他引：3
综述了我国重力固体潮研究领域的相关成果,包括积累大量观测数据,建立国际潮汐基准和独立的国际标定系统,利用小参数扰动法发展了地球潮汐理论模型,用计算机演绎法实施潮汐位展开,用残差信号对数据作预处理,用小波分析方法设计滤波器,用远近区结合法解算海潮负荷,用大气重力格林函数法解算气压对重力场观测的影响,测定了地球的近周日自由摆动参数,将固体潮汐研究成果应用于地震和重力测量,对重力仪进行静电反馈改造,精密测定了仪器相位滞后和对超导重力仪进行了标定等内容,讨论了今后研究展望。 相似文献
10.
扰动重力梯度是扰动重力位的二阶导数,相对于其他重力场元素能更多地反映变化的不规则地球产生的高频信息。在使用高阶次球谐系数模型获取大范围高分辨率的扰动重力梯度数据时,存在重复运算多、计算效率低下、耗时较长的问题。针对该问题,推导了简化计算公式,将中间变量提取出来作为全局参数和局部参数单独进行计算、存储,从而有效减少重复运算;并在简化公式的基础上,提出了扰动重力梯度张量快速异构并行算法,利用CUDA（compute unified device architecture）实现了梯度全张量在GPU端的并行计算。根据Txx、Tyy、Tzz三个分量满足Laplace条件验证了算法可靠性,并与传统串行算法进行了计算效率对比,实验结果表明,相较于串行算法,所提算法可减少90%以上计算耗时,可将计算效率提高60倍以上。最后利用该算法基于2 190阶EIGEN6C4模型快速构建了5′×5′分辨率的全球扰动重力梯度全张量图,计算结果显示了扰动重力梯度同地形、地球质量分布变化的相关性及其在全球范围内的数值特征。 相似文献
11.
利用球冠谐分析方法提取不同波长重力场异常 总被引：2，自引：0，他引：2
介绍球冠谐分析方法在重力场研究中的基本理论和计算方法。探讨了球冠谐系数与波长的关系，以及利用球冠谐分析方法提取不同波长的重量场力场异常，进而研究深部地壳结构的问题，最后给出一个实例。 相似文献
12.
L. F. Muratov Dr. 《GeoJournal》1991,23(3):207-214
The mathematical model of Raleigh convection on the rotating Earth in deepwater ocean depression is generalized for the case including the meridional temperature gradient. A steadystate thermal shear flow, in the origin of convective instability induced by this gradient has an effect contrary to the stabilizing influence of the Earth rotation. The stability of this flow has been studied with respect to the three-dimensional disturbances. Critical parameters determining the convection are calculated for the Kuril-Kamchatka and Japan trenches. The velocity components of tidal flow have been calculated using the hypothesis of Prandtl mixing way for bottom layer of trenches and the dynamic Richardson number has been calculated. It was noted that dynamic stability condition in bottom layers of the Kuril-Kamchatka and Japan trenches vary within tidal cycle. The periodical component for harmonics O1 and M2 has been calculated. 相似文献
13.
Modeling Sediment Suspensions in an Idealized Tidal Embayment: Importance of Tidal Asymmetry and Settling Lag 总被引：1，自引：0，他引：1
Suspended sediment transport processes in a short tidal embayment with a simple geometry are investigated using analytic and
numerical models. On the basis of numerical results, the horizontal gradient of depth-averaged suspended sediment concentration
can be parameterized with a combination of the first harmonic and mean. Using the parameterization, the solution of the analytic
model is obtained. Evaluation of the major terms from the solution of the analytic model shows that a quarter-diurnal frequency
is significant near the mouth while a semidiurnal component dominates the interior area. The settling lag consists of local
and nonlocal components. The local phase lag is a function of the ratio between tidal period and settling time. The nonlocal
phase lag is determined by the phase difference between tidal velocity and the horizontal gradient of sediment concentration
and by the strength of erosion and horizontal advection. 相似文献
14.
Importance of Orthogonalization Algorithm in Modeling Conditional Distributions by Orthogonal Transformed Indicator Methods 总被引：1，自引：0，他引：1
A. E. Tercan 《Mathematical Geology》1999,31(2):155-173
The orthogonal transformed indicator approach to conditional cumulative distribution functions is based on the decomposition of the indicator variogram matrix as a matrix product. This paper explores the manner in which the decomposition algorithm affects the conditional cumulative distribution function as estimated by orthogonal transformed indicator kriging. Five decomposition algorithms are considered: spectral, Cholesky, symmetric, Cholesky-spectral, and simultaneous decompositions. Impact of the algorithms on spatial orthogonality and order relations problems is examined and their performances together with indicator kriging are compared using a real dataset. 相似文献
15.
为预测不同径流过程影响下的盐水入侵强度,以长江口南支上段为研究对象,采用实测资料和理论分析相结合,建立了以大通流量和农历日期快速估算氯度值的经验模型。首先,以徐六泾实测潮位资料结合调和分析理论,在考虑11个主要分潮情况下证明日均潮差为半月周期函数,提出了用农历日期估算日均潮差的方法;其次,采用东风西沙实测氯度资料,选用不同函数形式,分析了以支汊盐水倒灌为主的情况下日均氯度对径流、潮差的量化响应关系;最后,提出了指数函数形式的氯度预测经验模型,模型计算值与实测值之间的决定系数在0.8以上。提出的经验模型可由大通流量快速估算特定位置的盐度,为相关的工程和规划研究提供了便捷途径。 相似文献
16.
声波速度-频移衰减联合层析成像检测技术 总被引：1，自引：1，他引：0
混凝土构件中存在的诸如松散、空洞、缝隙夹层等缺陷,不仅造成声波速度的变化,而且对声波具有较强的吸收衰减作用,利用声波速度CT和衰减CT联合检测技术是检测混凝土构件工程质量的有效方法。介绍了声波速度CT检测原理和SIRT算法、接收波信号频移与介质衰减吸收系数的关系,导出了适用于CT成像反演算法的介质吸收因数沿射线路径的积分与频移参数的关系表达式。对存在松散和空洞缺陷的两种混凝土构件模型的声波检测结果,分别进行了速度CT和频移衰减CT处理,处理结果表明,声波速度和频移衰减联合层析成像检测技术能够获得更加准确可靠的检测效果。 相似文献
17.
Spatial orthogonality of the principal components computed from coregionalized variables 总被引：6，自引：0，他引：6
P. Goovaerts 《Mathematical Geology》1993,25(3):281-302
Within the frame of the linear model of coregionalization, this paper sets up equations relating the variogram matrix of the principal components extracted from the variance-covariance matrix to the diagonal variogram matrices of the regionalized factors. The spatial orthogonality of the principal components is investigated in three situations: the intrinsic correlation, two basic structures with independent nugget components, three basic structures with independent nugget components and uncorrelated subsets of variables. Two examples point out that the correlation between the principal components may be nonnegligible at short distances, especially if the correlation structure changes according to the spatial scale considered. For one of the two case studies, an orthogonal varimax rotation of the first principal components is found to greatly reduce the spatial correlation between some of them. 相似文献
18.
时频域高分辨地震层序识别 总被引：5，自引：0，他引：5
地震信号频率随着时间的不稳定变化包含了地下反射层序特征的重要信息,时频分析是检测地震信号局部谱特征的重要工具。为适应实际地震信号处理,对S变换改进后得到一种新的广义S变换,用于分析和补偿地震信号的高频成分,得到了精细的地震层序识别剖面。实际资料处理表明,它对砂岩油气藏的成层特征的分析具有分辨率高和高信噪比的优点。地震信号的广义S变换时频谱分解可作为地震层序识别和解释的重要补充。 相似文献
19.
A. E. Rodin 《Astronomy Reports》2011,55(2):132-141
We suggest a new approach to the detection of gravitational waves using observations of a group of millisecond pulsars. In
contrast to the usual method, based on increasing the accuracy of the arrival times of pulses by excluding possible distorting
factors, our method supposes that the additive phase noise that is inevitably present even in the most accurate observational
data has various spectral components, which have characteristic amplitudes and begin to appear on different time scales. We
use the “Caterpillar” (Singular Spectral Analysis, SSA) method to decompose the signal into its components. Our initial data
are the residuals of the pulse arrival times for six millisecond pulsars. We constructed the angular correlation function
for components of the decomposition of a given number, whose theoretical form for the case of an isotropic and homogeneous
gravitational-wave background is known. The individual decomposition components show a statistically significant agreement
with the theoretical expectations (correlation coefficient ρ = 0.92 ± 0.10). 相似文献
20.
基于改进K-SVD字典学习方法的地震数据去噪 总被引：2，自引：0，他引：2
为实现更好的地震数据去噪技术,笔者引入一种新的算法:快速迭代收缩阀值法(FISTA),通过FISTA和K-奇异值分解(K-SVD)不断迭代更新K-SVD字典,利用更新得到的K-SVD字典对地震数据进行稀疏表示,去除稀疏系数中较小的数值,使数据中的随机噪声得到压制。对层状模型合成地震记录,Marmousi模型合成地震记录以及实际地震数据进行对比实验,得出FISTA算法较OMP算法能更好地提高地震数据的信噪比,同时有效地保护了反射信号。 相似文献