共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
多源图像配准技术分析与展望 总被引:50,自引:2,他引:48
在给出多源图像配准的定义后,将常见的图像配准方法分为基于图像灰度的方法和基于图像特征的方法两大类。以此为分类基础,对国内外现有的图像配准技术和方法进行了分析和评述,并重点介绍了基于图像特征的配准方法。随后对图像配准技术所面临的主要难题作了分析。最后介绍了图像配准在军事、遥感、医学等领域的应用,并展望了其未来的发展。 相似文献
3.
Scott A. Sarra 《Engineering Analysis with Boundary Elements》2011,35(1):68-76
Radial basis function (RBF) methods that employ infinitely differentiable basis functions featuring a shape parameter are theoretically spectrally accurate methods for scattered data interpolation and for solving partial differential equations. It is also theoretically known that RBF methods are most accurate when the linear systems associated with the methods are extremely ill-conditioned. This often prevents the RBF methods from realizing spectral accuracy in applications. In this work we examine how extended precision floating point arithmetic can be used to improve the accuracy of RBF methods in an efficient manner. RBF methods using extended precision are compared to algorithms that evaluate RBF methods by bypassing the solution of the ill-conditioned linear systems. 相似文献
4.
René De Borst 《International Journal of Fracture》2006,138(1-4):241-262
Standard domain-based discretization methods that have been developed for continuous media are not well suited for treating
propagating (or evolving) discontinuities. Indeed, they are approximation methods for the solution of partial differential
equations, which are valid on a domain. Discontinuities divide this domain into two or more parts. Conventionally, special
interface elements methods are placed a priori between the continuum finite elements to capture discontinuities at locations where they are expected to emerge. More recently,
discretization methods have been proposed, which are more flexible than standard finite element methods, while having the
potential to capture propagating discontinuities in a robust, efficient and accurate manner. Examples are meshfree methods,
finite element methods that exploit the partition-of-unity property of finite element shape functions, and discontinuous Galerkin
methods. In this contribution, we shall present an overview of these novel discretization techniques for capturing propagating
discontinuities, including a comparison of their similarities and differences. 相似文献
5.
描述芯片或电力系统运行规律的常用数学模型是高维微分代数方程组,其中的微分方程组太大,线性多步法和Runge-Kutta法等经典数值方法均不能有效求解。为求解这些微分方程组,借鉴常微分方程经典数值方法的A稳定定义,提出了波形松弛方法A稳定(强A稳定),给出了基于θ方法的波形松弛方法 A稳定(强A稳定)和非A稳定的条件,以及几个支持理论结果的数值算例。研究结果表明WR方法并非天然继承底层方法的A稳定性,为使波形松弛方法 A稳定,需要使用A稳定的底层方法和适当的分裂函数,这为刚性方程WR方法的构造奠定了理论基础。此外,借鉴经典数值方法的B稳定定义,提出了波形松弛方法的B稳定(强B稳定),给出了波形松弛方法强B稳定的条件。 相似文献
6.
L. Marin L. Elliott P. J. Heggs D. B. Ingham D. Lesnic X. Wen 《International journal for numerical methods in engineering》2004,60(11):1933-1947
In this paper, several boundary element regularization methods, such as iterative, conjugate gradient, Tikhonov regularization and singular value decomposition methods, for solving the Cauchy problem associated to the Helmholtz equation are developed and compared. Regularizing stopping criteria are developed and the convergence, as well as the stability, of the numerical methods proposed are analysed. The Cauchy problem for the Helmholtz equation can be regularized by various methods, such as the general regularization methods presented in this paper, but more accurate results are obtained by classical methods, such as the singular value decomposition and the Tikhonov regularization methods. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
7.
Jarmo Niemi 《International journal for numerical methods in engineering》1995,38(16):2829-2836
A general family of single-step methods for use in first-order ODEs is presented. This family of methods, called SS3-methods, embraces generalized trapezoidal methods, SS21-methods, α-methods and many other well-known methods, thus providing a good basis for comparison of these methods. Corresponding parameter values of SS3 methods for these methods are presented. The analysis of SS3-methods is restricted to linear and symmetric systems. Stability, convergence, accuracy, numerical dissipation and overshoot of the methods are considered. The conditions for algorithm parameters to exhibit good characteristics in these respects are given. It is shown that the optimal subfamily of SS3-methods coincides with α-methods. 相似文献
8.
本文介绍了七种测定P-S-N曲线的方法。并且用五种材料的实验数据对上述测定方法作了分析比较。在比较了几种方法的优缺点的基础上,提出了选择试验方法的建议和结论。 相似文献
9.
介绍了直流电阻的三种数字化检测方法;对三种方法进行分析并给出了测量结果的不确定度;给出了直流电阻检测中可选择的方法. 相似文献
10.
11.
本文介绍了七种测定P-S-N曲线的方法。并且用五种材料的实验数据对上述测定方法作了分析比较。在比较了几种方法的优缺点的基础上,提出了选择试验方法的建议和结论。 相似文献
12.
高强铝合金的应力腐蚀测试方法综述与评价 总被引:2,自引:0,他引:2
综述了高强铝合金应力腐蚀的各种测试方法及其原理与应用情况,通过分析与评价各应力腐蚀性能测试方法的优缺点,可以看出,用单一方法评价铝合金的应力腐蚀性能及其机制是有局限性的,需要通过多种方法的相互印证进行综合分析. 相似文献
13.
关于空气不偶合装药初始冲击压力计算的分析 总被引:4,自引:0,他引:4
通过对5种不偶合装药初始冲击压力计算的理论分析,阐述了几种主要方法对计算结果的影响以及计算中存在的问题。通过比较,建议采用不偶合装药初始冲击压力计算方法。 相似文献
14.
15.
Detection of voltage sag sources based on instantaneous voltage and current vectors and orthogonal Clarke?s transformation 总被引:1,自引:0,他引:1
Polajzer B. Stumberger G. Seme S. Dolinar D. 《Generation, Transmission & Distribution, IET》2008,2(2):219-226
Different methods for voltage sag source detection are discussed. They are based either on disturbance energy, voltage-current characteristic or active (real) current component. It is shown that, in the cases of asymmetrical voltage sags, both current-based methods known from literature do not work well. These two methods are therefore generalised using a vector-space approach. Furthermore, three new methods are introduced using orthogonal Clarke's transformation, which can be used to detect the sources of those voltage sags provoked by earth faults. All the discussed methods for voltage sag source detection have been tested by applying extensive simulations, laboratory tests and field testing. The results obtained show the very high effectiveness of the proposed methods, which are superior to the methods known from literature, especially for detecting sources of asymmetrical voltage sags. 相似文献
16.
In this paper, four methods for the through the thickness response evaluation of laminated composite and sandwich plates are comparatively evaluated in terms of their characteristics and numerical accuracy. The laminated composite and sandwich plates are subjected to thermo-mechanical loading. The four methods include two post-processor-type methods and two re-analysis-type methods. The post-processor-type methods based on the three-dimensional stress equilibrium equations and the three-dimensional thermo-elasticity equations. And the re-analysis methods are based on the incorporation of the nonlinear through the thickness displacements recovered using post-processing technique in the re-analysis phase. The accuracy of the proposed methods for the evaluation of the through the thickness responses of the laminated plates are assessed via numerical examples of various configurations of laminated plates. Also, applicability and computational efficiencies of the methods are discussed.
This research was supported in part by a grant from the BK-21 program for Mechanical and Aerospace Engineering Research at Seoul National University. The authors also gratefully acknowledge the financial support from the Ministry of Science and Technology through the National Laboratory Programs. 相似文献
17.
J. S. Arora A. I. Chahande J. K. Paeng 《International journal for numerical methods in engineering》1991,32(7):1485-1525
Multiplier methods used to solve the constrained engineering optimization problem are described. These methods solve the problem by minimizing a sequence of unconstrained problems defined using the cost and constraint functions. The methods, proposed in 1969, have been determined to be quite robust, although not as efficient as other algorithms. They can be more effective for some engineering applications, such as optimum design and control of large scale dynamic systems. Since 1969 several modifications and extensions of the methods have been developed. Therefore, it is important to review the theory and computational procedures of these methods so that more efficient and effective ones can be developed for engineering applications. Recent methods that are similar to the multiplier methods are also discussed. These are continuous multiplier update, exact penalty and exponential penalty methods. 相似文献
18.
Jürgen Geiser 《Journal of Engineering Mathematics》2007,57(1):79-98
Numerical methods are described and results are presented for a system of convection–diffusion dispersion–reaction equations.
Discretization methods that were developed earlier by the author are used. The methods allow large time steps for simulating
the transport–reaction model of a waste disposal. With higher-order discretization methods, based on finite-volume methods,
one may use large time steps without loss of accuracy. A multi-physical multi-dimensional equation is broken down into simpler
physical and one-dimensional equations. These simpler equations are handled with locally higher-order discretization methods
and the results are coupled by operator-splitting methods. An improved explicit time-discretization method, with embedded
analytical solutions, for the convection–reaction equation and an implicit time-discretization diffusion–dispersion equation
is described. For the numerical experiments the underlying program-tool R
3
T is briefly introduced and the main concepts are presented. Benchmark problems for testing the discretization methods of higher
order are described. Real-life problems for simulating radioactive-waste disposals with underlying flowing groundwater are
presented and discussed. 相似文献
19.
20.
J. M. Franco F. Petriz 《International journal for numerical methods in engineering》1995,38(22):3855-3887
Adaptive two-step direct integration methods are constructed for the integration of second-order semidiscrete evolution equations possessing oscillatory solutions. The methods are based on a class of adaptive multistep methods for a semilinear test model whose frequency is known. They are constructed following the notion of diagonally implicit RK-methods by using efficient rational approximations to cos v, v ≥ 0. Our interest is centered on the dispersion (or phase errors) of the dominant components in the numerical oscillations when these methods are applied to a linear homogeneous test model. Two-step methods which have high order of dispersion (up to 12), whereas the algebraic order is relatively low (2 or 4), are derived. Applications of these methods to linear as well as non-linear test models and to semidiscretized hyperbolic equations reveal a good behaviour with regard to error propagation when they are compared with other conventional methods. 相似文献