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991.
992.
Ecological shelter zones reconstruction is an ecosystem restoration and conserva-tion project aimed to the ecological safety of nations,regions and basins. Reconstruction of ecological shelter zones of the upper reaches of the Yangtze River became one of the most important tasks of Western Development strategy. This article,taking Zhaotong as an exam-ple,studies the functional regionalization of ecological shelter zones. The study supplies a case for functional regionalization of small and medium regions whose main tasks are envi-ronment reservation. With the guidance of theories of functional regionalization,and based on the analysis of Zhaotong's natural,ecological and socioeconomic factors,the paper suggests five principles for factors selection. These principles include: (1) reversing order evaluation; (2) selecting main factors; (3) keeping the integrality of administrative regions of towns; and (4) making the products acceptable by local government. To analyze spatial status of selected factors,LUCC data in 2002,1:50,000 relief maps and town-unit socioeconomic statistical data in 2004 are used. RS and GIS tools are also applied to melt traditional and modern geo-graphical methods. This would be useful to functional regionalization research in mountain-ous areas. As a conclusion,the leading functional regions of ecological conservation or economic development are suggested,respectively. Zhaotong city is divided into two-level functional regions. The first-level includes three leading functional regions and they will lead developing direction of sub-regions. The second-level includes eight sub-regions,which are policy implemented regions,and will supply guidance to Zhaotong's ecological shelter zones reconstruction. 相似文献
993.
Application of horizontal-to-vertical (H/V) Fourier spectral ratio for analysis of site effect on rock (NEHRP-class B) sites in Taiwan 总被引:1,自引:0,他引:1
Vladimir Yu. Sokolov Chin-Hsiung Loh Wen-Yu Jean 《Soil Dynamics and Earthquake Engineering》2007,27(4):314-323
The frequency-dependent amplification for rock (NEHRP-class B) sites was studied using earthquake ground-motion database collected in Taiwan during implementation of the Taiwan Strong Motion Instrumentation Program. The database used includes several hundred records from earthquakes of ML 4.0–7.3 occurred between 1993 and 2004. The characteristics of amplification were evaluated using the well-known technique of horizontal-to-vertical Fourier spectral ratio (H/V) of the S-wave phase [Lermo J, Chavez-Garcia FJ. Site effect evaluation using spectral ratios with only one station. Bull Seism Soc Am 1993;83:1574–94]. The study allows us to analyze peculiarities of rock sites amplification in Northern and Eastern Taiwan. It was suggested to divide the NEHRP-class B site amplification into four types based on frequency of maximum amplification and the shape of amplification function. The applicability of the technique was also checked for a few stiff and soft soil sites (NEHRP-classes D and E). 相似文献
994.
The paper outlines the most important results of the paraxial complex geometrical optics (CGO) in respect to Gaussian beams
diffraction in the smooth inhomogeneous media and discusses interrelations between CGO and other asymptotic methods, which
reduce the problem of Gaussian beam diffraction to the solution of ordinary differential equations, namely: (i) Babich’s method,
which deals with the abridged parabolic equation and describes diffraction of the Gaussian beams; (ii) complex form of the
dynamic ray tracing method, which generalizes paraxial ray approximation on Gaussian beams and (iii) paraxial WKB approximation
by Pereverzev, which gives the results, quite close to those of Babich’s method. For Gaussian beams all the methods under
consideration lead to the similar ordinary differential equations, which are complex-valued nonlinear Riccati equation and
related system of complex-valued linear equations of paraxial ray approximation. It is pointed out that Babich’s method provides
diffraction substantiation both for the paraxial CGO and for complex-valued dynamic ray tracing method. It is emphasized also
that the latter two methods are conceptually equivalent to each other, operate with the equivalent equations and in fact are
twins, though they differ by names.
The paper illustrates abilities of the paraxial CGO method by two available analytical solutions: Gaussian beam diffraction
in the homogeneous and in the lens-like media, and by the numerical example: Gaussian beam reflection from a plane-layered
medium. 相似文献
995.
A spherical model of the Earth including a heterogeneous upper mantle and excited by the magnetic field of a magnetospheric ring current is constructed. The obtained synthetic data are used for testing a new approach to gradient geomagnetic sounding ensuring the immunity of the sought impedance to distortions caused by lateral heterogeneity of the Earth. It is shown that this approach significantly increases the informativeness of deep electromagnetic sounding. 相似文献
996.
O. K. Zakharova V. V. Spichak A. K. Rybin V. Yu. Batalev A. G. Goidina 《Izvestiya Physics of the Solid Earth》2007,43(4):297-303
The paper analyzes the correlation between the electrical conductivity and temperature in the upper crust of the Bishkek geodynamic research area (the Northern Tien Shan). Electrical conductivity profiles constructed from magnetotelluric data and thermograms from the boreholes near magnetotelluric sounding (MTS) points are used for estimations. The correlation analysis of conductivity and temperature profiles to depths of 3–4 km showed that, first, the correlation coefficients do not depend on the distance between the borehole and the nearest MTS point; second, the good correlation between the conductivity and temperature observed for the majority of borehole-MTS point pairs is accounted for by the fact that the study parameters vary with depth in a manner normal for laminated sedimentary rocks; and, third, a low correlation is due to specific features of the geological structure between the borehole and MTS point under consideration. 相似文献
997.
D. K. Nourgaliev P. G. Yasonov H. Oberhaensli F. Heller A. S. Borisov I. Yu. Chernova E. I. Akdasov B. V. Burov 《Izvestiya Physics of the Solid Earth》2007,43(10):836-843
The paper presents results demonstrating the possibility of using data on paleosecular magnetic variations for correlation of young deposits. Using Holocene deposits of the Aral Sea as an example, it is shown that the combination of paleo-and petromagnetic data can be used to reliably correlate sections in presently isolated parts of a basin, as well as to correlate paleohydrologic events and estimate their age with regard for absolute radiocarbon datings. It is established that the most significant drop in the Aral Sea level occurred more than 2000–2500 yr ago and less significant drops that occurred later are dated at about 1500, 750–1050, and 270–500 yr ago. 相似文献
998.
M. Yu. Andreev D. V. Blagoveshchensky V. M. Vystavnoi V. S. Mingalev G. I. Mingaleva 《Geomagnetism and Aeronomy》2007,47(4):502-509
The experimental ionograms of the oblique-incidence sounding of the ionosphere, obtained on the St. Petersburg-Spitsbergen high-latitude HF radio path during the magnetically quiet period December 14–15, 2001, are compared with the model calculations of radiowave trajectories. For this purpose, the corresponding oblique-incidence ionograms are numerically synthesized using the technique based on the shooting method and the computer program for constructing HF radiowave trajectories. The three-dimensional electron density distribution, calculated using the mathematical model of the high-latitude ionosphere previously developed at the Polar Geophysical Institute (PGI), is used to model radio propagation. The numerical calculations make it possible mainly to explain the specific features of the experimental data on the oblique-incidence sounding of the ionosphere. 相似文献
999.
The discrepancy between the model and measured magnetic fields, which can be described by the contribution of field-aligned currents, has been determined. The division of the initial data array into the individual data sets with different IMF values makes it possible to estimate the dependence of field-aligned currents on IMF. 相似文献
1000.
In this study, we formulate an improved finite element model‐updating method to address the numerical difficulties associated with ill conditioning and rank deficiency. These complications are frequently encountered model‐updating problems, and occur when the identification of a larger number of physical parameters is attempted than that warranted by the information content of the experimental data. Based on the standard bounded variables least‐squares (BVLS) method, which incorporates the usual upper/lower‐bound constraints, the proposed method (henceforth referred to as BVLSrc) is equipped with novel sensitivity‐based relative constraints. The relative constraints are automatically constructed using the correlation coefficients between the sensitivity vectors of updating parameters. The veracity and effectiveness of BVLSrc is investigated through the simulated, yet realistic, forced‐vibration testing of a simple framed structure using its frequency response function as input data. By comparing the results of BVLSrc with those obtained via (the competing) pure BVLS and regularization methods, we show that BVLSrc and regularization methods yield approximate solutions with similar and sufficiently high accuracy, while pure BVLS method yields physically inadmissible solutions. We further demonstrate that BVLSrc is computationally more efficient, because, unlike regularization methods, it does not require the laborious a priori calculations to determine an optimal penalty parameter, and its results are far less sensitive to the initial estimates of the updating parameters. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献