In the present work, we introduce and explain a method of solution of the radiative transfer equation based on a thin cloud model. The efficiency of this method to retrieve dynamical chromospheric parameters from Stokes I profiles of Ca II 854.2 nm line showing spectral emission is investigated. The analyzed data were recorded with the Crisp Imaging Spectro-Polarimeter (CRISP) at Swedish 1-m So...

The development of advanced laboratory-based imaging hyperspectral sensors, such as SisuCHEMA, has created an opportunity to extract compositional information of mineral mixtures from spectral images. Determining proportions of minerals on rock surfaces based on spectral signature is a challenging approach due to naturally-occurring minerals that exist in the form of intimate mixtures, and grai...

Abstract: This paper discusses several methods of power spectrum estimation, respectively using the indirect method and Welch method to estimate power spectrum distribution through the acquisition of vibration signals of circuit breakers, and use the AR hybrid model to estimate different orders of power spectrum estimation. Under different length of data, the order selection method can be deter...

Hyperspectral imaging is a promising non-invasive method for applications in conservation of painting. With its ability to capture both spatial and spectral information which relates to physical characteristics of materials, the identification of pigments and its spatial distribution across the painting is now possible. In this work, The Scream (1893) by Edvard Munch is acquired using a hypersp...

We propose a spectral imaging method for piecewise "macropixel" objects, which allows a regular digital camera to be converted into a digital snapshot spectral imager by equipping the camera with only a disperser and a demultiplexing algorithm. The method exploits a "multiplexed spectrum" intensity pattern, i.e., the superposition of spectra from adjacent different image points, formed on the i...

The formula for the spectral moments is expanded in a series consisting of autocorrelation terms. By using the autocorrelation extrapolation inherent in the maximum entropy method (MEM) for spectral analysis, it is found that good estimates of the moments can be found from a very low order autoregressive model. The motivation for this investigation came from results obtained during spectral ana...

We survey recent literature focused on the following spectral sparsification question: Given an integer n and > 0, does there exist a function N(n, ) such that for every collection of C1, . . . ,Cm of n×n real symmetric positive semidefinite matrices whose sum is the identity, there exists a weighted subset of size N(n, ) whose sum has eigenvalues lying between 1− and 1 + ? We present the algor...

Stable and spectrally accurate numerical methods are constructed on arbitrary grids for partial di erential equations. These new methods are equivalent to conventional spectral methods but do not rely on speci c grid distributions. Speci cally, we show how to implement Legendre Galerkin, Legendre collocation, and Laguerre Galerkin methodology on arbitrary grids. Research supported by AFOSR gran...

We extend the Bloch-decomposition based time-splitting spectral method introduced in an earlier paper [13] to the case of (non-)linear Klein-Gordon equations. This provides us with an unconditionally stable numerical method which achieves spectral convergence in space, even in the case where the periodic coefficients are highly oscillatory and/or discontinuous. A comparison to a traditional pse...

*Correspondence: [email protected] 2School of Science, Jiangnan University, Lihu Road, Wuxi, 214122, China Full list of author information is available at the end of the article Abstract In the study of pattern formation in bi-stable systems, the extended Fisher-Kolmogorov (EFK) equation plays an important role. In this paper, a Fourier pseudo-spectral method for solving the EFK equation in ...