排序方式: 共有17条查询结果,搜索用时 0 毫秒
11.
Lithuanian Mathematical Journal - We prove that any beta distribution can be simulated by means of a sequence of distributions defined via multiplicative functions in a short interval. 相似文献
12.
The curse of dimensionality is based on the fact that high dimensional data is often difficult to work with. A large number of features can increase the noise of the data and thus the error of a learning algorithm. Feature selection is a solution for such problems where there is a need to reduce the data dimensionality. Different feature selection algorithms may yield feature subsets that can be considered local optima in the space of feature subsets. Ensemble feature selection combines independent feature subsets and might give a better approximation to the optimal subset of features. We propose an ensemble feature selection approach based on feature selectors’ reliability assessment. It aims at providing a unique and stable feature selection without ignoring the predictive accuracy aspect. A classification algorithm is used as an evaluator to assign a confidence to features selected by ensemble members based on their associated classification performance. We compare our proposed approach to several existing techniques and to individual feature selection algorithms. Results show that our approach often improves classification performance and feature selection stability for high dimensional data sets. 相似文献
13.
Adnan A. S. Elkhaldy Dnyaneshwar Gaikwad Richard J. Staples Afef Janen Yannic Boni 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):871-876
AbstractO, O’-Dialkyl and alkylene dithiophosphatogold (III)dichloride complexes of the type [(RO)2PS2]AuCl2 and [S2POGO]AuCl2, where R?=?Et, nPr, iPr, iBu, Ph, cyclohexyl and cyclopentyl, where G?=?CMe2CMe2-, have been synthesized in 80-90% yields by reaction of the corresponding acid or sodium salts of the appropriate dithiophosphoric acids in 1:1 ratio with gold (III) chloride in dry dichloromethane at room temperature. The compounds have been characterized by elemental analyses, IR and (1H, l3C, and 31P) NMR. The crystal structure of [S2POCMe2CMe2O]AuCl2, was determined. These new complexes have shown their growth inhibiting potential against various bacterial strains with moderate to good activity. 相似文献
14.
15.
In this Note, we consider the problem of the existence of conformal metrics with prescribed scalar curvature on the standard sphere , . We give new existence and multiplicity results based on a new Euler–Hopf formula type. Our argument also has the advantage of extending the well known results due to Y. Li (1995) [10]. 相似文献
16.
AbstractNew allelochemicals were identified through bio-guided fractionation from the ethyl acetate of seeds extracts, which was the most autotoxic compared to the other plant parts. Phytochemical investigation of the seeds extracts of C. arabica by spectroscopy analyses has led to identify two new dammarane type triterpenes (4 and 9), with nine known analogues (1???3, 5???8, 10 and 11), a new cucurbitane triterpene (12), acylated dehydrodiconiferyl alcohol (13), and three highly oxygenated flavonols (14?16). The most autotoxic compounds on germination and seedling growth were elucidated as dammarane type triterpenes. However, less autotoxic effect was recorded by an inhibition under 50% for most of the identified flavonoids. These results suggest that those autotoxic substances may be used as a new bio-herbicide that may contribute to manage the distribution of C. arabica in agronomic field. 相似文献
17.
Kritsadi Thetpraphi Minh Quyen Le Afef Houachtia Pierre‐Jean Cottinet Lionel Petit David Audigier Jeff Kuhn Gil Moretto Jean‐Fabien Capsal 《Advanced Optical Materials》2019,7(13)
The interdisciplinary approach presented here creates next‐generation large mirrors using electroactive polymer (EAP) actuators without classical glass abrasive polishing (“live mirrors”). The outstanding electromechanical coupling properties of terpolymer are taken advantage of, particularly when doped with plasticizer, e.g., diisononyl phthalate (DINP). This doped terpolymer creates a large strain response as well as excellent mechanical energy density under relatively low electric fields. Classical EAPs (e.g., polyurethane, silicone) require extremely high input voltages to reach sufficient mechanical strain. Using the high‐permittivity doped terpolymer and the concept of stacking multilayers, high displacements and large forces are generated. The actuation performance of multilayered terpolymer filled with DINP has been proven to shape mirror glass with a preliminary prototype of an 8‐layer actuator stack. The experimental results demonstrate surface deformations under load conditions of several microns. This is large enough to usefully control large optical telescope mirrors. This technology may enable much larger high‐quality optical mirror systems for ground‐ and space‐based astronomy and communications telescopes. 相似文献