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排序方式: 共有4263条查询结果,搜索用时 15 毫秒
81.
《Operations Research Letters》2020,48(4):460-466
Area under ROC curve (AUC) is a performance measure for classification models. We propose new distributionally robust AUC models (DR-AUC) that rely on the Kantorovich metric and approximate AUC with the hinge loss function, and derive convex reformulations using duality. The DR-AUC models outperform deterministic AUC and support vector machine models and have superior worst-case out-of-sample performance, thereby showing their robustness. The results are encouraging since the numerical experiments are conducted with small-size training sets conducive to low out-of-sample performance. 相似文献
82.
The magnetic anisotropy field in thin films with in-plane uniaxial anisotropy can be deduced from the VSM magnetization curves
measured in magnetic fields of constant magnitudes. This offers a new possibility of applying rotational magnetization curves
to determine the first- and second-order anisotropy constant in these films. In this paper we report a theoretical derivation
of rotational magnetization curve in hexagonal crystal system with easy-plane anisotropy based on the principle of the minimum
total energy. This model is applied to calculate and analyze the rotational magnetization process for magnetic spherical particles
with hexagonal easy-plane anisotropy when rotating the external magnetic field in the basal plane. The theoretical calculations
are consistent with Monte Carlo simulation results. It is found that to well reproduce experimental curves, the effect of
coercive force on the magnetization reversal process should be fully considered when the intensity of the external field is
much weaker than that of the anisotropy field. Our research proves that the rotational magnetization curve from VSM measurement
provides an effective access to analyze the in-plane anisotropy constant K
3 in hexagonal compounds, and the suitable experimental condition to measure K
3 is met when the ratio of the magnitude of the external field to that of the anisotropy field is around 0.2.
Supported by the National Natural Science Foundation of China (Grant Nos. 90505007 and 10774061)
Recommended by LI FaShen 相似文献
83.
We study the asymptotic properties of both the horizontal and vertical shift functions based on independent ranked set samples
drawn from continuous distributions. Several tests derived from these shift processes are developed. We show that by using
balanced ranked set samples with bigger set sizes, one can decrease the width of the confidence band and hence increase the
power of these tests. These theoretical findings are validated through small-scale simulation studies. An application of the
proposed techniques to a cancer mortality data set is also provided.
Part of the research was conducted while Kaushik Ghosh was visiting Statistical Research and Applications Branch of the National
Cancer Institute on an Intergovernmental Personnel Assignment. 相似文献
84.
B. G. Konopelchenko L. Martínez Alonso E. Medina 《Theoretical and Mathematical Physics》2007,151(3):820-830
Based on the Lenard relations, we completely classify integrable deformations of general algebraic curves. We construct the
general solution of the Lenard relation from the invariance condition with respect to an element of the Galois group of the
curve. We give some examples and also some associated conservation laws.
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 151, No. 3, pp. 458–469, June, 2007. 相似文献
85.
The paper addresses bivariate surface fitting problems, where data points lie on the vertices of a rectangular grid. Efficient
and stable algorithms can be found in the literature to solve such problems. If data values are missing at some grid points,
there exists a computational method for finding a least squares spline by fixing appropriate values for the missing data.
We extended this technique to arbitrary least squares problems as well as to linear least squares problems with linear equality
constraints. Numerical examples are given to show the effectiveness of the technique presented.
AMS subject classification (2000) 65D05, 65D07, 65D10, 65F05, 65F20 相似文献
86.
采用直流磁控溅射并通过优化工艺参数,在(100)Si衬底上成功制备了高度(100)择优的MgO薄膜和MgO/TiN双层膜结构.对 (100)MgO择优取向温度影响机理做了详细讨论,并利用XRD,AFM,FESEM等手段研究了在(100)Si和(100)TiN/Si两种衬底上,不同工艺条件下MgO薄膜的表面和断面微观结构,表征了MgO薄膜的柱状生长结构和与TiN薄膜的良好外延关系.在对薄膜光学特性的研究中,利用Sellmeier模型获得了Si上MgO薄膜在可见光波段的折射率参数(550 nm处折射率为1.6
关键词:
MgO薄膜
择优取向
直流溅射
折射率拟合 相似文献
87.
Paul Godin 《Journal of Differential Equations》2002,183(1):224-238
We give a complete discussion of the C∞ or analytic regularity of blow-up curves for Cauchy problems or some mixed problems for the Liouville equation in one space dimension. In the case of mixed problems, the regularity results depend on the boundary condition: actually, we show the existence of a sequence of boundary conditions for which the regularity of the blow-up curve is better than in the general case. 相似文献
88.
为实现μs档条纹相机扫描非线性标定,建立了基于延时可调信号源和外触发激光器的条纹相机μs档扫描非线性标定系统,弥补了标准具法的不足。系统通过延时值的递增,得到条纹相机扫描速度在全扫程的变化。系统中时间关系抖动来源主要是测试设备延时抖动和条纹相机触发延时抖动。时间抖动测试与分析显示,条纹相机延时抖动±0.6ns,测试设备延时抖动±0.3ns,系统总时间抖动±0.7ns。系统时间抖动会造成最终时间轴信息的起伏。大量数值模拟分析表明,时间轴起伏对系统时间抖动的影响±2ns,在可以接受的范围内。因此,该系统能够胜任条纹相机μs扫程时间信息的测量标定。 相似文献
89.
T. S. K. Moothathu 《Annals of the Institute of Statistical Mathematics》1985,37(1):473-479
Summary This paper presents the maximum likelihood estimators (MLEs) of the Lorenz curve and Gini index of the exponential distribution,
their exact distributions and moments. All these MLEs are shown to converge almost surely and in therth mean. Further their asymptotic distributions are obtained. Here we use only very simple arguments to derive certain results
that are very useful in statistical study of ‘inequality’. 相似文献
90.