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Relevant bibliographies by topics / SPECTRUM APPLICATIONS

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Academic literature on the topic 'SPECTRUM APPLICATIONS'

Author: Grafiati

Published: 11 September 2023

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Journal articles on the topic "SPECTRUM APPLICATIONS"

1

Long, Junbo, Haibin Wang, and Peng Li. "Applications of Fractional Lower Order Frequency Spectrum Technologies to Bearing Fault Analysis." Mathematical Problems in Engineering 2019 (August 27, 2019): 1–24. http://dx.doi.org/10.1155/2019/7641383.

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The traditional spectral analysis method is used to study the characteristics of bearing fault signals in frequency domain, which is reasonable and effective in general cases. However, it is proved that the fault signals have heavy tails in this paper, which are α stable distribution, and 1<α<2, and even the noises belong to α stable distribution. Then the conventional spectral analysis methods degenerate and even fail under α stable distribution environment. Several improved frequency spectral analysis methods are proposed employing fractional lower order covariation or fractional lower order covariance in this paper, including fractional lower order Blackman-Tukey covariation spectrum (FLOBTCS), fractional lower order periodogram covariation spectrum (FLOPCS), and fractional lower order welch covariation spectrum (FLOWCS). In order to suppress side lobe and improve resolution, we present novel fractional lower order autoregression (FLO-AR) and fractional lower order autoregressive moving average (FLO-ARMA) parameter model frequency spectrum methods, and the calculation steps are summarized. The proposed spectrum methods are compared with the existing methods based on second-order statistics under Gaussian and SαS distribution environments, and the results show that the new algorithms have better performance than the traditional methods. Finally, the improved methods are applied to estimate frequency spectrums of the normal and outer race fault signals, and it is demonstrated that they are effective for fault diagnosis.

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2

Корсунская, Юлия, and Yulia Korsunskaja. "Heuristic model of solar X-ray spectrum according to satellite data for geophysical applications." Solar-Terrestrial Physics 5, no. 3 (2019): 75–86. http://dx.doi.org/10.12737/stp-53201909.

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Model and computational algorithm for recovering the X-ray component of the solar spectrum based on GOES XL (0.1–0.8 nm), XS (0.05–0.4 nm or 0.05–0.3 nm) and SDO QD (0.1–7 nm) channels data are presented. The model based the Mewe approximation of emission from optically thin plasmas that presents a temperature-like spectrum. The possibility to present the result spectrum as a superposition of Mewe spectrums placed in the solar absorbing atmosphere at one optical depth for its temperature parameter energy is suggested in this paper. So the model is a variation of the multi-temperature approximation. Spectrum parameters are determined on the basis of support functions, approximation expressions for which are given in appendix.

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3

ESTAREMI, YOUSEF. "On the Composition of Conditional Expectation and Multiplication Operators." Kragujevac Journal of Mathematics 46, no. 6 (2022): 883–94. http://dx.doi.org/10.46793/kgjmat2206.883e.

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In this paper, ﬁrst we provide some necessary and suﬃcient conditions for quasi- normality and quasi- hyponormality of weighted conditional type operators. And then the spectrum, residual spectrum, point spectrum and spectral radius of weighted conditional type operators are computed. As an application, we give an equivalent conditions for weighted conditional type operators to be quasinilpotent. Also, some examples are provided to illustrate concrete applications of the main results.

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4

Moran, Timothy. "Applications of Sound Spectrum Analysis." Physics Teacher 45, no. 2 (2007): 93–95. http://dx.doi.org/10.1119/1.2432085.

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5

Xie, B. S., S. Y. Zhou, and L. X. Wu. "AN INTEGRATED MINERAL SPECTRAL LIBRARY USING SHARED DATA FOR HYPERSPECTRAL REMOTE SENSING AND GEOLOGICAL MAPPING." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B5-2020 (August 24, 2020): 69–75. http://dx.doi.org/10.5194/isprs-archives-xliii-b5-2020-69-2020.

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Abstract. Mineral spectral library (MSL) is the foundation of hyperspectral remote sensing, and a significant tool of storing and managing massive mineral spectral data to facilitate the matching or identifying of unknown rocks and minerals conveniently and fast. However, mineral spectral data are scattered and stored in different spectral libraries worldwide, which behave different spectral resolutions, mineral categories and measurement parameters, and hinder its application in field investigation, mineral identification, landcover identification and geological mapping. An integrated MSL using shared data is developed currently in Central South University, China, to improve the properties of MSL. We collected the shared spectral data and related information (e.g., mineral attribute data, spectrometer information, etc.) worldwide, performed data cleaning measures to retain the qualified spectral data and consolidated all the data in a common framework so as to establish a reliable and comprehensive dataset, and developed an integrated MSL for data management and diversified applications. The user can analysis the target spectrum with the spectrum absorption characteristic parameters, and match the measured spectral curve with the reference spectrum in the integrated MSL to find the most similar spectrum curve. It’s crucial to note that a new spectrum classifier was designed to limit the scope of matching for improving the efficiency of identification when the experimental sample lacks the specific information. The integrated MSL is developed in B/S and C/S website environments. A demonstration of functions of the integrated MSL and its preliminary applications are introduced in the article.

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6

Cheng, Andrew Y. S., Jianhua Zhu, and Michael C. Y. Pau. "Characterization of a Noncolinear Acousto-Optic Tunable Filter and its Resolution Enhancement as a Near-Infrared Spectrometer." Applied Spectroscopy 55, no. 3 (2001): 350–55. http://dx.doi.org/10.1366/0003702011951768.

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An automatic near-infrared (NIR) spectrometer based on a noncolinear acousto-optic tunable filter (AOTF) is constructed for high-speed spectrometry. Its initial spectral characteristics are studied systematically for application. The AOTF is a solid-state, rugged, compact, and high-speed device and can be readily used for spectral measurement applications, but some broadening and overlapping effects will occur when it is used for the measurement of a narrow-band spectrum. In order to correct the spectral distortion and obtain a fine spectrum, a new resolution enhancement procedure, which combines conventional Fourier self-deconvolution (FSD) with our optimized evaluation function and objective parameters determination, is used to resolve the band-broadened and band-overlapped spectral lines. The self-deconvolved spectrum is in good agreement with the fine spectrum measured by a high-resolution grating spectrometer. This is, to our knowledge, the first resolution enhancement of an AOTF spectrum by analytical and numerical operation.

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7

Nikolaeva, Vera, and Evgeny Gordeev. "SPAM: Solar Spectrum Prediction for Applications and Modeling." Atmosphere 14, no. 2 (2023): 226. http://dx.doi.org/10.3390/atmos14020226.

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Solar Spectrum Prediction for Applications and Modeling (SPAM) is a new empirical model of solar X-ray, extreme ultraviolet and far ultraviolet radiation flux at the top of the Earth’s atmosphere. The model is based on 14 years of daily averaged TIMED spacecraft measurements from 2002 to 2016, when its sensors were regularly calibrated. We used a second-order parametrization of the irradiance spectrum by a single parameter—the F10.7 index—which is a reliable and consistently observed measure of solar activity. The SPAM model consists of two submodels for general and specific use. The first is the Solar-SPAM model of the photon energy flux in the first 190 spectral bands of 1 nm each, which can be used for a wide range of applications in different fields of research. The second model, Aero-SPAM, is designed specifically for aeronomic research and provides a photon flux for 37 specific wavelength intervals (20 wave bands and 16 separate spectral lines within the range of 5–105 nm, and an additional 121.5 nm Ly-alpha line), which play a major role in the photoionization of atmospheric gas particles. We provide the full set of parameterization coefficients that allows for the immediate implementation of the model for research and applications. In addition, we used the Aero-SPAM model to build a ready-to-use numerical application for calculating the photoionization rates of the main atmospheric components N2, O2, O, N and NO with known absorption and ionization cross sections.

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8

Pan, Mengguan, Baixiao Chen, and Minglei Yang. "A General Range-Velocity Processing Scheme for Discontinuous Spectrum FMCW Signal in HFSWR Applications." International Journal of Antennas and Propagation 2016 (2016): 1–13. http://dx.doi.org/10.1155/2016/2609873.

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Discontinuous spectrum signal which has separate subbands distributed over a wide spectrum band is a solution to synthesize a wideband waveform in a highly congested spectrum environment. In this paper, we present a general range-velocity processing scheme for the discontinuous spectrum-frequency modulated continuous wave (DS-FMCW) signal specifically. In range domain, we propose a simple time rearrangement operation which converts the range transform problem of the DS-FMCW signal to a general spectral estimation problem of nonuniformly sampled data. Conventional periodogram results in a dirty range spectrum with high sidelobes which cannot be suppressed by traditional spectral weighting. In this paper, we introduce the iterative adaptive approach (IAA) in the estimation of the range spectrum. IAA is shown to have the ability to provide a clean range spectrum. On the other hand, the discontinuity of the signal spectrum has little impact on the velocity processing. However, with the range resolution improved, the influence of the target motion becomes nonnegligible. We present a velocity compensation strategy which includes the intersweep compensation and in-sweep compensation. Our processing scheme with the velocity compensation is shown to provide an accurate and clean range-velocity image which benefits the following detection process.

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9

Fabila-Carrasco, John Stewart, and Fernando Lledó. "Covering Graphs, Magnetic Spectral Gaps and Applications to Polymers and Nanoribbons." Symmetry 11, no. 9 (2019): 1163. http://dx.doi.org/10.3390/sym11091163.

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In this article, we analyze the spectrum of discrete magnetic Laplacians (DML) on an infinite covering graph G ˜ → G = G ˜ / Γ with (Abelian) lattice group Γ and periodic magnetic potential β ˜ . We give sufficient conditions for the existence of spectral gaps in the spectrum of the DML and study how these depend on β ˜ . The magnetic potential can be interpreted as a control parameter for the spectral bands and gaps. We apply these results to describe the spectral band/gap structure of polymers (polyacetylene) and nanoribbons in the presence of a constant magnetic field.

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10

Gil', Michael. "Spectrum localization of a perturbed operator in a strip and applications." Opuscula Mathematica 41, no. 3 (2021): 395–412. http://dx.doi.org/10.7494/opmath.2021.41.3.395.

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Let \(A\) and \(\tilde{A}\) be bounded operators in a Hilbert space. We consider the following problem: let the spectrum of \(A\) lie in some strip. In what strip the spectrum of \(\tilde{A}\) lies if \(A\) and \(\tilde{A}\) are "close"? Applications of the obtained results to integral operators and matrices are also discussed. In addition, we apply our perturbation results to approximate the spectral strip of a Hilbert-Schmidt operator by the spectral strips of finite matrices.

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