共查询到20条相似文献,搜索用时 15 毫秒
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定义了单调收敛函数和交错收敛函数,并根据其收敛特点,提出并证明了加快其收敛速度的两个命题.算例表明其效果较好. 相似文献
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在标准形式的CES效用函数的基础上引入饱和需求量,得出扩展形式的CES效用函数,展现其新的数量特征,并进一步利用质量效用函数模型描述劣质品和吉芬商品的需求特性. 相似文献
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通过支持向量机(SVM)对客车车型的长,宽,高,宽长比等7个特征进行特征选择,得到的准确率最高的子集是长、宽、高、宽长比、宽高比,以它作为样本特征进行分类.对客车的4类车型进行分类,每类车型选择80个样本,50个样本进行训练,30个样本进行预测,结果表明:对1类车型的分类准确率可达到100%,对2类和4类车型可达到96%以上,对3类车可达到93%以上.得到了比选用长、宽、高作为特征进行分类更优的结果.然后运用加入参数寻优的SVM对客车的4类车型进行分类,并加以比较.基于高斯函数的特性,两次用到SVM进行机器学习时,核函数均选用RBF核函数. 相似文献
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Qi Zhang 《数学学报(英文版)》2014,30(3):517-524
A one-dimensional continuous function of unbounded variation on [0,1] has been constructed.The length of its graph is infnite,while part of this function displays fractal features.The Box dimension of its Riemann–Liouville fractional integral has been calculated. 相似文献
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本文研究了平面不可压缩的Navier-Stokes方程一个七模类Lorenz方程组的混沌行为问题.利用模式截断的方法,获得了一个七模类Lorenz方程组,证明了该方程组吸引子的存在性,并对其全局稳定性进行了分析和讨论.基于分岔图、最大李雅普诺夫指数、庞加莱截面、功率谱揭示了系统混沌行为的普适特征,仿真分析了系统动力学行为的演化过程. 相似文献
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Criterion on the limits of superprocesses 总被引:1,自引:0,他引:1
Yongjin Wang 《中国科学A辑(英文版)》1998,41(8):849-858
Starting with super-diffusion processes, the asymptotic behavior of the superprocesses on finite and infinite measure spaces
is systematically studied by general branching mechanisms. The complete features of their limits are described and a criterion
on their behavior is presented.
Project supported by the National Natural Science Foundation of China (Grant No. 19631010) and the Mathematical Centre of
the State Education Commission. 相似文献
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Mun Bae Lee 《Applied mathematics and computation》2011,217(10):5011-5014
Radial basis function interpolation on a set of scattered data is constructed from the corresponding translates of a basis function, which is conditionally positive definite of order m ? 0, with the possible addition of a polynomial term. In many applications, the translates of a basis function are scaled differently, in order to match the local features of the data such as the flat region and the data density. Then, a fundamental question is the non-singularity of the perturbed interpolation (N × N) matrix. In this paper, we provide some counter examples of the matrices which become singular for N ? 3, although the matrix is always non-singular when N = 2. One interesting feature is that a perturbed matrix can be singular with rather small perturbation of the scaling parameter. 相似文献
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The penetration function measures the effect of the boundary data on the energy of the solution of a second order linear elliptic
PDE taken over an interior subdomain. Here the coefficients of the PDE are functions of position and often represent the material
properties of non homogeneous media with microstructure. The penetration function is used to assess the accuracy of global-local
approaches for recovering local solution features from coarse grained solutions such as those delivered by homogenization
theory.
AMS subject classification (2000) 65N15, 78M40 相似文献
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借助于函数变换理论和灰色系统建模理论,并结合反余弦函数和线性函数的特点,提出了反余弦函数和线性函数相结合的变换方法并建立了一个改进的GM(1,1)模型.证明了这种变换一方面能提高序列的光滑比并压缩序列的级比;另一方面可以使还原误差减小.具体算例结果表明,经过反余弦函数和线性函数相结合建立的改进GM(1,1)模型的拟合精度优于传统GM(1,1)模型和基于反余弦函数变换的GM(1,1)模型的拟合精度. 相似文献
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在紧约束函数的梯度向量线性无关这一约束规范下,运用隐函数定理和直交投影的性质,给出约束最优化问题Kuhn-Tucker一阶必要条件的一个简洁证明. 相似文献
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Time irreversibility (asymmetry with respect to time reversal) is an important property of many time series derived from processes in nature. Some time series (e.g., healthy heart rate dynamics) demonstrate even more complex, multiscale irreversibility, such that not only the original but also coarse-grained time series are asymmetric over a wide range of scales. Several indices to quantify multiscale asymmetry have been introduced. However, there has been no simple generator of model time series with "tunable" multiscale asymmetry to test such indices. We introduce an asymmetric Weierstrass function W(A) (constructed from asymmetric sawtooth functions instead of cosine waves) that can be used to construct time series with any given value of the multiscale asymmetry. We show that multiscale asymmetry appears to be independent of other multiscale complexity indices, such as fractal dimension and multiscale entropy. We further generalize the concept of multiscale asymmetry by introducing time-dependent (local) multiscale asymmetry and provide examples of such time series. The W(A) function combines two essential features of complex fluctuations, namely fractality (self-similarity) and irreversibility (multiscale time asymmetry); moreover, each of these features can be tuned independently. The proposed family of functions can be used to compare and refine multiscale measures of time series asymmetry. 相似文献
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梁锡坤 《高等学校计算数学学报》2012,34(1):52-60
0引言科学和工程计算中,函数的近似表示一直是一个重要课题.近似方法一般可归结为插值、逼近和拟合三种基本类型,经历长期发展,函数逼近方法[1-3]十分丰富.诸如Taylor 相似文献
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We use Magnus methods to compute the Evans function for spectral problems as arise when determining the linear stability of
travelling wave solutions to reaction-diffusion and related partial differential equations. In a typical application scenario,
we need to repeatedly sample the solution to a system of linear non-autonomous ordinary differential equations for different
values of one or more parameters as we detect and locate the zeros of the Evans function in the right half of the complex
plane.
In this situation, a substantial portion of the computational effort—the numerical evaluation of the iterated integrals which
appear in the Magnus series—can be performed independent of the parameters and hence needs to be done only once. More importantly,
for any given tolerance Magnus integrators possess lower bounds on the step size which are uniform across large regions of
parameter space and which can be estimated a priori. We demonstrate, analytically as well as through numerical experiment, that these features render Magnus integrators extremely
robust and, depending on the regime of interest, efficient in comparison with standard ODE solvers.
AMS subject classification (2000) 65F20 相似文献
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Conditions for the uniqueness of the optimal solution in linear semi-infinite programming 总被引:1,自引:0,他引:1
In this paper, we establish different conditions for the uniqueness of the optimal solution of a semi-infinite programming problem. The approach here is based on the differentiability properties of the optimal value function and yields the corresponding extensions to the general linear semi-infinite case of many results provided by Mangasarian and others. In addition, detailed optimality conditions for the most general problem are supplied, and some features of the optimal set mapping are discussed. Finally, we obtain a dimensional characterization of the optimal set, provided that a usual closedness condition (Farkas-Minkowski condition) holds. 相似文献
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Adel Mohsen 《Applied mathematics and computation》2010,217(7):3330-3337
Sinc bases are developed to approximate the solutions of linear and nonlinear Volterra integral and integro-differential equations. Properties of these sinc bases and some operational matrices are first presented. These properties are then used to reduce the integral and integro-differential equations to systems of linear or nonlinear algebraic equations. Numerical examples illustrate the pertinent features of the method and its applicability to a large variety of problems. The examples include convolution type, singular as well as singularly-perturbed problems. 相似文献