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171.
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Mohamed Charif Soufiane El Adraoui Mounirh Khalid Asmaa Zugari Mohamed I. Yaich Mohsine Khalladi 《Optik》2014
The current density (JE), the piecewise linear recursive convolution (PLRC) and the constant convolution recursive (CRC) techniques are developed and integrated into the transmission line matrix (TLM) algorithm. A comparison of these three schemes according to the criteria of accuracy and CPU time is presented. Numerical experiments show that JE provides the most accurate solution and requires the least CPU time; PLRC is nearly as accurate but consumes more CPU time than CRC. 相似文献
173.
The trust region method which originated from the Levenberg–Marquardt (LM) algorithm for mixed effect model estimation are considered in the context of second level functional magnetic resonance imaging (fMRI) data analysis. We first present the mathematical and optimization details of the method for the mixed effect model analysis, then we compare the proposed methods with the conventional expectation-maximization (EM) algorithm based on a series of datasets (synthetic and real human fMRI datasets). From simulation studies, we found a higher damping factor for the LM algorithm is better than lower damping factor for the fMRI data analysis. More importantly, in most cases, the expectation trust region algorithm is superior to the EM algorithm in terms of accuracy if the random effect variance is large. We also compare these algorithms on real human datasets which comprise repeated measures of fMRI in phased-encoded and random block experiment designs. We observed that the proposed method is faster in computation and robust to Gaussian noise for the fMRI analysis. The advantages and limitations of the suggested methods are discussed. 相似文献
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177.
Sabine Kopec Emilio Martínez-Núñez Juan Soto Daniel Peláez 《International journal of quantum chemistry》2019,119(21):e26008
We present a generalization of the transition state search using chemical dynamics simulations (TSSCDS) methodology (discussed in a previous study) which allows the topographical characterization of intermolecular potential energy surfaces (IPES) for non-covalently bound complexes (vdW-TSSCDS). Starting from a single random input geometry, we show that vdW-TSSCDS is able to globally and automatically locate stationary points of an IPES, even in limiting cases such as extremely flat regions or nontrivial topologies (eg, bifurcation points). The basic idea is the expression of the connectivity matrix in block structure, where diagonal blocks correspond to the isolated fragments and off-diagonal blocks provide the intermolecular connectivity. To this end, we introduce a new definition of bound or not, in a non-covalent sense, utilizing an extra set of van der Waals distances, which encompasses all kinds of non-covalent distances. To discuss the use of the vdW-TSSCDS method, we present a series of 2-body van der Waals systems, namely, Ar-Benzene (3D), N2-Benzene (6D) and H2O-Benzene (9D). Finally, we further illustrate its capabilities by presenting some applications for n-body problems (n > 2), (H2O)2-Benzene (12D) and (H2O)3-Benzene (21D), as well as to a reactive, fully-flexible, system (Benzene-NO2)+ (39D) in which the simultaneous breaking/formation of both covalent and non-covalent interactions takes place. 相似文献
178.
在近红外光谱900-1700nm的波长范围内采集南疆羊肉的光谱数据,来研究水分含量的快速无损检测.为减弱非目标因素对光谱的影响,采用SNV和去趋势法对光谱数据进行预处理.为降低建模的复杂度,去除共线性的影响,采用连续投影算法和相关系数法相结合选取8个特征波长变量,最后使用PLS和ELM算法分别进行建模.实验表明,与采用全光谱波段建模相比,采用特征波长变量建模,PLS和ELM算法的运行时间都大大缩短,并且在运行时间和预测精度上,ELM算法均优于PLS算法.ELM算法采用8个特征波段变量建模,预测精度达到0.9768,均方误差为4.4291e-04,相关系数为0.7603,运行时间可控制在1e-04s之下,这可为研发羊肉水分含量的便携式检测装置提供理论参考. 相似文献
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Joint L1/Lp-regularized minimization in video recovery of remote sensing based on compressed sensing
L1 regularization and Lp regularization are proposed for processing recovered images based on compressed sensing (CS). L1 regularization can be solved as a convex optimization problem but is less sparse than Lp (0 < p < 1). Lp regularization is sparser than L1 regularization but is more difficult to solve. This paper proposes joint L1/Lp (0 < p < 1) regularization, which combines Lp regularization and L1 regularization. This joint regularization is applied to recover video of remote sensing based on CS. Joint regularization is sparser than L1 regularization but is as easy to solve as L1 regularization. A linearized Bregman reweighted iteration algorithm is proposed to solve the joint L1/Lp regularization problem. The performance and capabilities of the linearized Bregman algorithm and linearized Bregman reweighted algorithm for solving the joint L1/Lp regularization model are analyzed and compared through numerical simulations. 相似文献