Results 171 to 180 of about 152,938 (206)

Endmember Variability in Hyperspectral Analysis: Addressing Spectral Variability During Spectral Unmixing

IEEE Signal Processing Magazine, 2014
Variable illumination and environmental, atmospheric, and temporal conditions cause the measured spectral signature for a material to vary within hyperspectral imagery. By ignoring these variations, errors are introduced and propagated throughout hyperspectral image analysis.
Alina Zare, K C Ho
exaly   +2 more sources

Orthogonal Subspace Unmixing to Address Spectral Variability for Hyperspectral Image

IEEE Transactions on Geoscience and Remote Sensing, 2023
International audienceHyperspectral unmixing aims at estimating pure spectral signatures and their proportions in each pixel. In practice, the atmospheric effects, intrinsic variation of the spectral signatures of the materials, illumination, and ...
Longfei Ren, Danfeng Hong, Lianru Gao
exaly   +2 more sources

Spectral variability of atlantic forest species

2013 IEEE International Geoscience and Remote Sensing Symposium - IGARSS, 2013
This paper investigates the spectral variability of Brazilian Atlantic Forest trees. Spectroscopy data (reflectance and transmittance) of full sunlight leaves were collected. The root mean square difference between pairs of spectra were used to estimate within- and between-species variability.
Matheus Pinheiro Ferreira, Atilio E. B. Grondona, Silvia Beatriz Alves Rolim, Yosio Edemir Shimabukuro   +3 more
openaire   +1 more source

X-Ray Spectral Variability of 3C273

Space Science Reviews, 1985
3C273 has been monitored by EXOSAT over the period December 1983 to June 1984 in 4 observations. In the December observation the flux was high and the spectrum showed a power law index of 1.5 changing to 0.9 at~8 keV. In subsequent observations the flux dropped to~40% of its original value and the hard tail disappeared.
M.J.L. Turner, T. Courvoisier, R. Staubert, D. Molteni, J. Trumper   +4 more
openaire   +1 more source

Rapid Spectral Variability of DR Tau

Astrophysics and Space Science, 1998
The Classical T Tauri stars (CTTS) are pre-main sequence stars surrounded by an accretion disk. Material from the disk is being accreted by the central object, probably by a strong magnetic field anchored to the star (Konigl 1991). The accreted material is channelled down the magnetic field lines and free falls onto the star’s surface, forming strong ...
K. W. Smith, G. F. Lewis, I. A. Bonnell, P. S. Bunclark, J. P. Emerson   +4 more
openaire   +1 more source

Spectral variability of blazars

AIP Conference Proceedings, 2000
Broadband spectral characteristics of different subclasses of γ-ray blazars in different γ-ray intensity states are contrasted and discussed in the framework of currently popular leptonic jet models. Differences between quasars and BL-Lacs may be understood in terms of the dominance of different radiation mechanisms in the gamma-ray regime.
openaire   +1 more source

Spectral Analysis of Cardiovascular Variability Signals

1998
It is well known that the control mechanisms of heart rate and blood pressure, as well as of many other cardiovascular parameters, manifest themselves though beat-to-beat variations in the related signals1,2. The quantification of these variations, both in control conditions and after provocative tests, plays a fundamental role for a better ...
CERUTTI, SERGIO, BIANCHI, ANNA MARIA, MAINARDI, LUCA, SIGNORINI, MARIA GABRIELLA   +3 more
openaire   +2 more sources

Spectral variability of P Cyg

Astrophysics, 1994
In careful analysis of the CCD-spectra of P Cyg it was possible to identify 10 of the 43 lines that have been unidentified up to now. The majority of the latter belong to multiply ionized atoms. The conclusion is reached that there is anomalous heating in certain layers of the stellar wind.
G. L. Israelyan, A. G. Nikogosyan
openaire   +1 more source