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排序方式： 共有53条查询结果，搜索用时 343 毫秒
1.
林菁 《广东海洋大学学报》1996,(1)
分析了分频和ＣＴＣ计数采样中误读数的原因和解决方法，并利用微机软件实现非线性校正。此传感器用于位移测量系统中，具有０．０１ｍｍ的分辨率及优于１％的精度，可在－２０～６０℃温度范围内工作。 相似文献
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Numerical analyses for the Bragg resonant reflection of carrier waves associated long waves due to sinusoidally varying seabeds are performed by using a set of coupled ordinary differential equations derived from the Boussinesq equations. The Boussinesq equations are firstly approximated with the Fourier decomposition. The coupled governing equations are then derived and used to simulate evolution of both short and long wave components. It is also found that wave groups are generated by two carrier waves with slightly different frequencies. The wave energy of the initial wave components is transferred to other harmonic components during propagation over a long distance. Evolution and reflection of both short and long waves were largely affected by nonlinearity. 相似文献
4.
多圈涡旋等值线动力学的研究 总被引：1，自引：1，他引：1
将单圈涡旋等值线动力学推广到多圈涡旋的等值线动力学。在等值线动力学的框架内，实施了６组计算。结果显示出涡旋移行过程中逆时针打转的现象，该现象有清楚的前兆可寻。讨论了涡旋松紧程度对涡旋移向的影响以及涡旋非对称结构与涡旋移速之间的联系。这些结果与以往数值试验或动力学分析的结果较为一致。 相似文献
5.
拱坝系统三维非线性地震波动分析 总被引：18，自引：1，他引：18
本文将显式有限元结合外推人工边界的方法发展应用于三维非线性近场波动问题的研究。首次提出了拱坝－库水－地基系统三维非线性地震反应波动分析方法，并与传统的无质量地基分析方法进行了比较。 相似文献
6.
Li-Chung Wu Dong-Jiing Doong Beng-Chun Lee Laurence Zsu-Hsin Chuang Chia Chuen Kao 《Marine Geophysical Researches》2008,29(1):43-50
The purpose of this study is to discuss the influence of signal nonlinearity upon X-band radar observations. A method for
estimating the degree of nonlinearity by bispectral analysis was applied and discussed. We found that bispectral analyses
from spatial radar backscatter series are similar to results obtained from water level time series. In addition, the average
nonlinear degree from radar backscatter is related to wind speed. The accuracy of wave observations derived by consideration
of the nonlinear effect from radar backscatter was also investigated. The estimated error in wave height from the radar data
is also related to the degree of nonlinearity. In order to improve accuracy, the modulation transfer function method was applied
in order to eliminate the influence of nonlinearity. 相似文献
7.
Groundwater models need to account for detailed but generally unknown spatial variability (heterogeneity) of the hydrogeologic model inputs. To address this problem we replace the large, m-dimensional stochastic vector β that reflects both small and large scales of heterogeneity in the inputs by a lumped or smoothed m-dimensional approximation γθ∗, where γ is an interpolation matrix and θ∗ is a stochastic vector of parameters. Vector θ∗ has small enough dimension to allow its estimation with the available data. The consequence of the replacement is that model function f(γθ∗) written in terms of the approximate inputs is in error with respect to the same model function written in terms of β, f(β), which is assumed to be nearly exact. The difference f(β) − f(γθ∗), termed model error, is spatially correlated, generates prediction biases, and causes standard confidence and prediction intervals to be too small. Model error is accounted for in the weighted nonlinear regression methodology developed to estimate θ∗ and assess model uncertainties by incorporating the second-moment matrix of the model errors into the weight matrix. Techniques developed by statisticians to analyze classical nonlinear regression methods are extended to analyze the revised method. The analysis develops analytical expressions for bias terms reflecting the interaction of model nonlinearity and model error, for correction factors needed to adjust the sizes of confidence and prediction intervals for this interaction, and for correction factors needed to adjust the sizes of confidence and prediction intervals for possible use of a diagonal weight matrix in place of the correct one. If terms expressing the degree of intrinsic nonlinearity for f(β) and f(γθ∗) are small, then most of the biases are small and the correction factors are reduced in magnitude. Biases, correction factors, and confidence and prediction intervals were obtained for a test problem for which model error is large to test robustness of the methodology. Numerical results conform with the theoretical analysis. 相似文献
8.
A. Dermanis 《Journal of Geodesy》1998,72(2):71-100
Motivated by the existing theory of the geometric characteristics of linear generalized inverses of linear mappings, an attempt
is made to establish a corresponding mathematical theory for nonlinear generalized inverses of nonlinear mappings in finite-
dimensional spaces. The theory relies on the concept of fiberings consisting of disjoint manifolds (fibers) in which the domain
and range spaces of the mappings are partitioned. Fiberings replace the quotient spaces generated by some characteristic subspaces
in the linear case. In addition to the simple generalized inverse, the minimum-distance and the x
0-nearest generalized inverse are introduced and characterized, in analogy with the least-squares and the minimum-norm generalized
inverses of the linear case. The theory is specialized to the geodetic mapping from network coordinates to observables and
the nonlinear transformations (Baarda's S-transformations) between different solutions are defined with the help of transformation parameters obtained from the solution
of nonlinear equations. In particular, the transformations from any solution to an x
0-nearest solution (corresponding to Meissl's inner solution) are given for two- and three-dimensional networks for both the
similarity and the rigid transformation case. Finally the nonlinear theory is specialized to the linear case with the help
of the singular-value decomposition and algebraic expressions with specific geometric meaning are given for all possible types
of generalized inverses.
Received: 11 April 1996 / Accepted: 19 April 1997 相似文献
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