نتایج جستجو برای: empirical method
تعداد نتایج: 1801820 فیلتر نتایج به سال:
We have obtained optical spectrophotometry of 11 H II regions in the polar ring of NGC 2685 (the Helix galaxy), and have used these data to study the physical characteristics of the polar-ring H II regions. The H II regions have normal spectra with no suggestion of unusual density, temperature, extinction, or composition. Semi-empirical calculations yield high oxygen abundance estimates (0.8–1....
The proposed method for calculation of potential evapotranspiration is Penman-Monteith FAO method, but there are other methods that require less meteorological data but estimates close to the FAO Penman-Monteith method in different climatic conditions. Performance evaluation of these methods on the same basis is prerequisite for selecting an alternative approach in accordance with available da...
Abstract. We consider the problem of estimating an unknown vector θ from the noisy data Y = Aθ + ǫ, where A is a known m × n matrix and ǫ is a white Gaussian noise. It is assumed that n is large and A is ill-posed. Therefore in order to estimate θ, a spectral regularization method is used and our goal is to choose a spectral regularization parameter with the help of the data Y . We study data-d...
The effects of interstitial carbon on the electronic and mechanical properties of copper are studied theoretically. Semiempirical methodology, atomistic simulations, and first-principles density functional embedded cluster schemes are combined to extract some understanding of the diffusion process and related degradation of Cu/C composite materials under extremes of temperature and stress. High...
We consider the empirical risk minimization problem for linear supervised learning, with regularization by structured sparsity-inducing norms. These are defined as sums of Euclidean norms on certain subsets of variables, extending the usual l1-norm and the group l1-norm by allowing the subsets to overlap. This leads to a specific set of allowed nonzero patterns for the solutions of such problem...
An approximate theoretical formula for the distribution of aerodynamic load over arbitrary thick wings in incompressible flow is developed by combining three-dimensional results from thin-wing theory with two-dimensional results from thick-aerofoil theory. The formula is applied to two wings of identical planform, with 60 degrees trailing-edge sweepback and differing aerofoil thickness, which h...
We propose a new image segmentation technique called strings. A string is a variational deformable model that is learned from a collection of example objects rather than built from a priori analytical or geometrical knowledge. As opposed to existing approaches, an object boundary is represented by a one-dimensional multivariate curve in functional space, a feature function, rather than by a poi...
We describe a novel optimization method for finite sums (such as empirical risk minimization problems) building on the recently introduced SAGA method. Our method achieves an accelerated convergence rate on strongly convex smooth problems. Our method has only one parameter (a step size), and is radically simpler than other accelerated methods for finite sums. Additionally it can be applied when...
In this paper, we study the stability and generalization properties of penalized empirical-risk minimization algorithms. We propose a set of properties of the penalty term that is sufficient to ensure uniform β-stability: we show that if the penalty function satisfies a suitable convexity property, then the induced regularization algorithm is uniformly β-stable. In particular, our results imply...
A semiempirical theory of solid solubility in transition metal alloys is presented. The theory is based on writing the energy of formation of the solid solution as a sum of several contributions: a) a chemical contribution due to electronic redistribution in forming the alloy, b) an elastic contribution arising from the difference in size between solute and solvent atoms and c) a structural con...
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