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1.
针对利用波函数展开法进行三维地震响应研究中的坐标变换问题,提出了在两斜交柱坐标系间谐波函数空间坐标变换的辅助平面方法．通过建立与空间点对应的一系列辅助平面,将地震波三维散射研究中的谐波函数表达式从柱坐标系变换至辅助平面内的极坐标系,然后在辅助平面内运用Graf加法公式,将柱坐标系下的波函数表达式变换至与该柱坐标系斜交的另一柱坐标系下,从而将三维问题转换成二维问题进行处理,最终得到了斜交柱坐标系下内域问题和外域问题的坐标变换公式． 相似文献
2.
阐明重力场中完整坐标系、非完整坐标系及其之间的转换关系以及完整坐标系的存在对大地测量的意义．指出水准测量中的理论闭合差是由于它所参照的局部笛卡尔坐标系是一个非完整坐标系导致的，并给出了计算理论闭合差的严密公式． 相似文献
3.
Takehiko Mori Yasuaki Sudo Tomoki Tsutsui Shin Yoshikawa 《Bulletin of Volcanology》2008,70(9):1031-1042
Isolated-type tremors having two events with different dominant frequencies are characteristic seismological phenomena observed
during the fumarolic activity stage at Aso Volcano. These isolated tremors are called hybrid tremors (HBT) and comprise two
parts: an initial part named the “HF-part” with a dominant frequency in the high-frequency region (approximately 10 Hz) and
the following part named the “LF-part” with a dominant frequency in the low-frequency region (approximately 2 Hz). The LF-part
is observed after the HF-part, and the HBT is accompanied by a long-period tremor (LPT). Hypocenters and source parameters
are estimated using seismograms recorded at 64 stations around Nakadake crater. The amplitude distributions of all HF-parts
have almost similar trends. Similarly, the amplitude distributions of all LF-parts have almost similar trends. However, the
amplitude distributions of HF- and LF-parts are not similar. From these results, we proposed that the hypocenters and source
parameters of HF- and LF-parts are not common, but each of them have common hypocenters and source parameters. The hypocenter
region of HF-parts was estimated to be just beneath the fumarole region south of the 1st crater: the volume fluctuation is
the major source factor. The hypocenter region of LF-parts is estimated to be at a depth of approximately 300 m beneath the
first crater: the strike–slip component is the major source parameter. The hypocentral depth of LF-parts is located at the
upper end of the crack estimated to be the source of the LPTs. The LPTs and HBTs are observed almost simultaneously. We consider
that volcanic fluid is involved in the source mechanisms of both HBT and LPT. 相似文献
4.
Thc expressions of magnetic gradients due to 3-D homogeneous magnetized polyhedra are systematically derived and presented,
fronr which the forward problem of magnetic gradients of an arbitrary shaped geological body is solved. It is shown that in
the rotation of coordinate systems there is an essential difference between the transformation of magnetic fields and that
of their gradients. In a 2-D coordinate system a unified transformation formula of any order gradients can he derived, hut
cannot in the 3-D case. The calculations of synthetic models show the correctness of the expressioils or magnetic gradients.
Project supported by the National Natural Science Foundation of China. 相似文献
5.
Giuseppe Muscolino 《地震工程与结构动力学》1990,19(2):205-216
A method to evaluate the dynamic response of composite multiply connected primary-secondary systems is presented. For this purpose the nodal equations of motion of the composite system are given in ‘total’ and ‘relative’ coordinates. In the framework of the component-mode synthesis method a coordinate transformation, here defined as an admissible one, is used to reduce the nodal equations of motion. This coordinate transformation is theoretically and numerically compared with the coordinate transformation usually used in the literature, which generally gives larger errors with respect to the former when a reduced number of nodes is considered. 相似文献
6.
Increasing numerical efficiency of iterative solution for total least-squares in datum transformations 总被引：1，自引：0，他引：1
Cartesian coordinate transformation between two erroneous coordinate systems is considered within the Errors-In-Variables (EIV) model. The adjustment of this model is usually called the total Least-Squares (LS). There are many iterative algorithms given in geodetic literature for this adjustment. They give equivalent results for the same example and for the same user-defined convergence error tolerance. However, their convergence speed and stability are affected adversely if the coefficient matrix of the normal equations in the iterative solution is ill-conditioned. The well-known numerical techniques, such as regularization, shifting-scaling of the variables in the model, etc., for fixing this problem are not applied easily to the complicated equations of these algorithms. The EIV model for coordinate transformations can be considered as the nonlinear Gauss-Helmert (GH) model. The (weighted) standard LS adjustment of the iteratively linearized GH model yields the (weighted) total LS solution. It is uncomplicated to use the above-mentioned numerical techniques in this LS adjustment procedure. In this contribution, it is shown how properly diminished coordinate systems can be used in the iterative solution of this adjustment. Although its equations are mainly studied herein for 3D similarity transformation with differential rotations, they can be derived for other kinds of coordinate transformations as shown in the study. The convergence properties of the algorithms established based on the LS adjustment of the GH model are studied considering numerical examples. These examples show that using the diminished coordinates for both systems increases the numerical efficiency of the iterative solution for total LS in geodetic datum transformation: the corresponding algorithm working with the diminished coordinates converges much faster with an error of at least 10-5 times smaller than the one working with the original coordinates. 相似文献
7.
George D. Manolis Richard P. Shaw Stavros Pavlou 《Soil Dynamics and Earthquake Engineering》1999,18(1):952
The purpose of this work is to present three methods of analysis for elastic waves propagating in two dimensional, elastic nonhomogeneous media. The first step, common to all methods, is a transformation of the governing equations of motion so that derivatives with respect to the material parameters no longer appear in the differential operator. This procedure, however, restricts analysis to a very specific class of nonhomogeneous media, namely those for which Poisson's ratio is equal to 0.25 and the elastic parameters are quadratic functions of position. Subsequently, fundamental solutions are evaluated by: (i) conformal mapping in conjunction with wave decomposition, which in principle allows for both vertical and lateral heterogeneities; (ii) wave decomposition into pseudo-dilatational and pseudo-rotational components, which results in an Euler-type equation for the transformed solution if medium heterogeneity is a function of one coordinate only; and (iii) Fourier transformation followed by a first order differential equation system solution, where the final step involving inverse transformation from the wavenumber domain is accomplished numerically. Finally, in the companion paper numerical examples serve to illustrate the above methodologies and to delineate their range of applicability. 相似文献
8.
T. N. Kaseke M. E. Thompson 《Stochastic Environmental Research and Risk Assessment (SERRA)》1997,11(1):1-16
Abstract: Linear continuous time stochastic Nash cascade conceptual models for runoff are developed. The runoff is modeled
as a simple system of linear stochastic differential equations driven by white Gaussian and marked point process noises. In
the case of d reservoirs, the outputs of these reservoirs form a d dimensional vector Markov process, of which only the dth
coordinate process is observed, usually at a discrete sample of time points. The dth coordinate process is not Markovian.
Thus runoff is a partially observed Markov process if it is modeled using the stochastic Nash cascade model. We consider how
to estimate the parameters in such models. In principle, maximum likelihood estimation for the complete process parameters
can be carried out directly or through some form of the EM (estimation and maximization) algorithm or variation thereof, applied
to the observed process data. In this research we consider a direct approximate likelihood approach and a filtering approach
to an algorithm of EM type, as developed in Thompson and Kaseke (1994). These two methods are applied to some real life runoff
data from a catchment in Wales, England. We also consider a special case of the martingale estimating function approach on
the runoff model in the presence of rainfall. Finally, some simulations of the runoff process are given based on the estimated
parameters. 相似文献
9.
Miloš Cimbálník 《Studia Geophysica et Geodaetica》1991,35(3):133-144
Summary Short history of the National Geodetic Reference System (NGRS), Common Network of the Socialist Countries (CNSC/42/58, Czech S-42), CNSC/42/83 (S-42/83) — result of the second adjustment of the CNSC in Moscow 1983; the state and accuracy of the existing horizontal control.Low accuracy of national coordinate systems, especially the scale. Conform transformation of the global system into the national and calculation of corrections (dx,dy) by quadratic, cubic or biquadratic transformation under condition of minimum differences between the national and new system. Adjustment of length and direction corrections, numerical example.The proposed method indicates the possibility of improving national coordinate systems on a permanent basis with the aid of improved and, therefore, changing global systems. 相似文献
10.
Ecological network analysis of an urban energy metabolic system 总被引：2，自引：1，他引：1
Jinyun Zhang Yan Zhang Zhifeng Yang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(5):685-695
Analysis of the structure and function of urban energy metabolic systems is an important tool to facilitate compliance with
China’s current energy-conservation policy. In this study, we used network throughflow analysis and network utility analysis
to analyze the structure of an urban energy metabolic system and the complex relationships among its components. Using weight
distributions in the network flow matrix, we determined the system structure; using the sign distribution in the network utility
matrix, we determined the relationships between pairs of components. We then developed an ecological network model using Beijing
in 1995, 2000, 2005, and 2007 as an example of how the model can be used to understand the system’s structure and function.
The model’s components were the energy exploitation, transformation, consumption, and recovery sectors. Network throughflow
analysis revealed that the energy transformation and consumption sectors had high weights (34–45%) in all 4 years, whereas
the energy recovery sector had small weights (<5%) and the energy exploitation had low to intermediate weights (which decreased
from 23% in 1995 to 11% in 2007). Network utility analysis revealed that the ecological relationships between the energy transformation
and exploitation sectors, the energy consumption and transformation sectors, and the energy consumption and exploitation sectors
did not change, but that the ecological relationships between the energy recovery sector and other sectors changed greatly.
Our analysis of Beijing’s urban energy metabolic system provided guidance for optimizing the system’s structure and adjusting
the relationships among the sectors. 相似文献
11.
本文利用解的叠加原理求解了轨道扰动微分方程组,构建了扰动位系数与轨道和星间距变率的观测方程,并分别引入非线性改正项.通过惯性坐标系与运动坐标系的转换求解状态转移方程组,分析了观测方程的低频误差特征,导出了目前常用的消除剩余星间距变率低频误差的五参数或七参数经验公式.此外,根据非惯性力模型误差是分段标定的特点,提出利用三次样条函数来处理低频误差,通过模拟计算表明三次样条函数处理低频误差略优于七参数.最后,处理实际的GRAEC Level-1b数据,解算了2006年1月至2009年12月期间的月时变重力场模型UCAS_Grace01,通过在不同区域进行比较可以得出本文计算的时变重力场模型与国际官方机构精度基本是一致的结论. 相似文献
12.
In this paper, we describe a non‐linear constrained inversion technique for 2D interpretation of high resolution magnetic field data along flight lines using a simple dike model. We first estimate the strike direction of a quasi 2D structure based on the eigenvector corresponding to the minimum eigenvalue of the pseudogravity gradient tensor derived from gridded, low‐pass filtered magnetic field anomalies, assuming that the magnetization direction is known. Then the measured magnetic field can be transformed into the strike coordinate system and all magnetic dike parameters – horizontal position, depth to the top, dip angle, width and susceptibility contrast – can be estimated by non‐linear least squares inversion of the high resolution magnetic field data along the flight lines. We use the Levenberg‐Marquardt algorithm together with the trust‐region‐reflective method enabling users to define inequality constraints on model parameters such that the estimated parameters are always in a trust region. Assuming that the maximum of the calculated gzz (vertical gradient of the pseudogravity field) is approximately located above the causative body, data points enclosed by a window, along the profile, centred at the maximum of gzz are used in the inversion scheme for estimating the dike parameters. The size of the window is increased until it exceeds a predefined limit. Then the solution corresponding to the minimum data fit error is chosen as the most reliable one. Using synthetic data we study the effect of random noise and interfering sources on the estimated models and we apply our method to a new aeromagnetic data set from the Särna area, west central Sweden including constraints from laboratory measurements on rock samples from the area. 相似文献
13.
A. S. Cherepantsev 《Izvestiya Physics of the Solid Earth》2007,43(12):1047-1055
The possibility of determining parameters of complex geophysical processes is considered in terms of nonlinear dynamics. In accordance with modern approaches in the theory of nonlinear dynamic systems, the number of independent parameters controlling the behavior of a nonlinear system can be estimated from the available time realization of only one of these parameters. Model calculations showed that the dimension of the phase space of a dynamic system can be estimated from a sample of one variable. Experimental data on variations in the apparent electric resistivity (AER) and the relative vertical movement of the surface (RVMS) in a seismically active region are analyzed and the dimension of the dynamic system determining its behavior in the phase space is estimated. The resulting estimates of the embedding dimension m = 7?8 for AER variations and m = 6 for RVMS variations possibly characterize the complexity of the dynamic system describing the given fields. The method presented in the paper is also applied to the analysis of the degree of connectivity of different dynamic systems and their parameters. By the connectivity we mean the number of independent parameters simultaneously involved in the formation of the dynamic behavior of various physical fields. The model estimates demonstrate the possibility of such an approach. It is shown that variations in the AER in perpendicular directions are described by a general system of dynamic equations, whereas dynamic systems controlling the AER field and the RVMSs are interconnected only partially. The resulting dimension m = 12 estimated for the AER-RVMS system provides an estimate for the number of common controlling parameters: n = (8 + 6)?12 = 2. The methods and results presented in the paper are applicable to the construction of models of complex geophysical processes and the development and the development of new approaches and methods of identification of prognostic characteristics for the behavior of physical fields of various origins. 相似文献
14.
L. Klimeš 《Studia Geophysica et Geodaetica》2006,50(3):431-447
Whereas the ray-centred coordinates for isotropic media by Popov and Pšenčík are uniquely defined by the selection of the
basis vectors at one point along the ray, there is considerable freedom in selecting the ray-centred coordinates for anisotropic
media. We describe the properties common to all ray-centred coordinate systems for anisotropic media and general conditions,
which may be imposed on the basis vectors. We then discuss six different particular choices of ray-centred coordinates in
an anisotropic medium. This overview may be useful in choosing the ray-centred coordinates best suited for a particular application.
The equations are derived for a general homogeneous Hamiltonian of an arbitrary degree and are thus applicable both to the
anisotropic-ray-theory rays and anisotropic common S-wave rays. 相似文献
15.
在地磁与空间物理学实验研究和理论研究中,无论是观测资料和实验数据,还是理论计算和数值模拟结果,都需要组织在一定的坐标框架中,或者用一定的函数(函数系)来表达.坐标系或函数系的选择对于合理描述资料和发现自然规律是十分重要的环节.本文综述了地磁与空间物理研究中经常使用的20多种坐标系,着重探索这些坐标系的基本设计思想和相互联系,追踪它们的发展演化轨迹,从而加深对资料组织和坐标系选择的理解. 相似文献
16.
I. A. Shirokov N. A. Zharinov B. P. Pertsev K. M. Anokhina 《Journal of Volcanology and Seismology》2009,3(6):405-413
We consider the results of ground tilt observations in the area of Klyuchevskoi Volcano, Kamchatka at the Klyuchi and Apakhonchich
stations using photoelectric tiltmeters. An anomalous tilt was recorded during a period of increased activity in the summit
crater of Klyuchevskoi Volcano in November 1979. In January and February 1980 three more cases of anomalous tilting before
the volcano’s active periods were observed. The tilts exhibit some common kinematic features that are quite consistent with
the activity periods. Various disturbing influences were estimated as affecting the observations of tilts related to seismic
and volcanic events. For the first time in Kamchatka, the parameters of the five principal elastic-tide waves have been determined.
Sea tides exerted an indirect effect on the amplitude factors γ(M2) on the E-W component at both sites to decrease them relative
to the global value, γ(M2) = 0.7. We investigated the influence of sea tides on the elastic solid earth tide along the Trans-Kamchatka
and Kola traverses. The observed and theoretical γ(M2) factors at both traverses situated in different geodynamic areas are
in approximate agreement. 相似文献
17.
Xiaping Ma Kegen Yu Jean-Philippe Montillet Xiaoxing He 《Studia Geophysica et Geodaetica》2018,62(4):535-561
The local tie vector, which connects the different space geodetic techniques at a co-located site, plays an important role in the realization of the International Terrestrial Reference Frame (ITRF). This paper presents a new method to determine the tie vector between the GNSS and very long baseline interferometry tracking points. The parameters of the local tie vector and the axes offsets are introduced into constraint equations. The parameters are then resolved using the 3D constrained least squares adjustment. With the surveying data collected at two different sites (Kunming and Urumqi) in China, the proposed method can precisely determine the local tie vectors in a geocentric frame. The root mean square error (RMSE) is (1.2, 2.3 and 1.5 mm) and (1.0, 1.5 and 1.4 mm) for the three coordinate components at the sites in Kunming and Urumqi, respectively. The offset between the primary and secondary axes of the VLBI telescopes is estimated to be 7.5 mm in Kunming’s site and 4.0 mm in Urumqi’s site, and the corresponding RMSE is 1.8 mm and 2.0 mm for the two sites, respectively. 相似文献
18.
Jitka Hájková 《Studia Geophysica et Geodaetica》2011,55(3):515-528
A mathematical model used for determination of a local geoid model by combining airborne gravity disturbances and the Earth
Gravitational Model 2008 (EGM08) is shortly reviewed. The precision of the estimated local geoid model of Taiwan is tested
by its comparison with the “real” geoid at Global Satellite Navigation Systems (GNSS)/levelling points. The same comparison
at GNSS/levelling points is done for the geoid evaluated only by using EGM08. Conclusions concerning a rate of improvement
of the “global” geoid from EGM08 using the “local” geoid from airborne gravity data are presented. 相似文献
19.
A convection-diffusion equation arises from the conservation equations in miscible and immiscible flooding, thermal recovery, and water movement through desiccated soil. When the convection term dominates the diffusion term, the equations are very difficult to solve numerically. Owing to the hyperbolic character assumed for dominating convection, inaccurate, oscillating solutions result. A new solution technique minimizes the oscillations. The differential equation is transformed into a moving coordinate system which eliminates the convection term but makes the boundary location change in time. We illustrate the new method on two one-dimensional problems: the linear convection-diffusion equation and a non-linear diffusion type equation governing water movement through desiccated soil. Transforming the linear convection diffusion equation into a moving coordinate system gives a diffusion equation with time dependent boundary conditions. We apply orthogonal collocation on finite elements with a Crank-Nicholson time discretization. Comparisons are made to schemes using fixed coordinate systems. The equation describing movement of water in dry soil is a highly non-linear diffusion-type equation with coefficients varying over six orders of magnitude. We solve the equation in a coordinate system moving with a time-dependent velocity, which is determined by the location of the largest gradient of the solution. The finite difference technique with a variable grid size is applied, and a modified Crank-Nicholson technique is used for the temporal discretization. Comparisons are made to an exact solution obtained by similarity transformation, and with an ordinary finite difference scheme on a fixed coordinate system. 相似文献
20.
The sampling theorem in two dimensions univocally defines a surface, provided that its values are known at points disposed on a regular lattice. If the data are irregularly spaced, the usual procedure is first to interpolate the surface on a regular grid and then to contour the interpolated data: however, the resulting surface will not necessarily assume the prescribed values on the irregular grid. One way to obtain this result is to introduce a transformation of the coordinates such that all the original data points are transferred into part of the nodes of a regular grid. The surface is then interpolated in the points correspondent to the other crosspoints of the regular grid; the contour lines are determined in the transformed plane and then, using the inverse coordinate transformation, are transferred back to the original plane where they will certainly be congruent with the original data points. Nonetheless, the resulting surface is very sensitive to the interpolation method used: two algorithms for that are analyzed. The first (harmonization) corresponds to the determination of the potential of an electrical field whose contour conditions are those defined by the data points. The second method consists in two dimensional statistical estimation (krigeing); in particular, the effects of different choices for the data auto-covariance function are discussed. The solutions are compared and some practical results are shown. 相似文献