scholarly journals Postprocessing of Infrared Reflectography to Support the Study of a Painting: The Case of Vivarini's Polyptych

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Laura Fragasso ◽  
Nicola Masini
Keyword(s):  
Principal Component Analysis ◽  
Spectral Sensitivity ◽  
Diagnostic Technique ◽  
Principal Component ◽  
Ccd Camera ◽  
Positioning System ◽  
Spectral Indices ◽  
Study Case ◽  
Infrared Reflectography ◽  
Ir Reflectography

Infrared (IR) reflectography is an imaging diagnostic technique widely used to study and evaluate the assessment of paintings' conservation state. The study case analyzed in this paper is related to a polyptych panel attributed to Vivarini's workshop conserved in the “Sigismondo Castromediano” Museum in Lecce. The painting's IR reflectography has been acquired through a CCD camera with spectral sensitivity ranging 400–1150 nm and manual positioning system. In order to offset the technological limits of the CCD camera, reflectograms have been processed through Principal Component Analysis and spectral indices. Postprocessing provided information related to the different pictorial drafting and restoration works, as well as emphasized graphic details and shadings, useful to improve the knowledge of the painting techniques.

scholarly journals Faint solar analogues at the limit of no reddening

2019 ◽  
Vol 629 ◽  
pp. A33 ◽  
Author(s):  
R. E. Giribaldi ◽  
G. F. Porto de Mello ◽  
D. Lorenzo-Oliveira ◽  
E. B. Amôres ◽  
M. L. Ubaldo-Melo
Keyword(s):  
Principal Component Analysis ◽  
Solar System ◽  
Effective Temperature ◽  
Flux Distribution ◽  
Principal Component ◽  
Surface Gravity ◽  
The Sun ◽  
Spectral Indices ◽  
Atmospheric Parameters ◽  
Solar System Bodies

Context. The flux distribution of solar analogues is required for calculating the spectral albedo of solar system bodies such as asteroids and trans-Neptunian objects. Ideally a solar analogue should be comparatively faint as the target of interest, but very few analogues fainter than V = 9 mag have been identified so far. Only atmospheric parameters equal to solar guarantee a flux distribution equal to solar as well, while only photometric colours equal to solar do not. Reddening is also a factor to consider when selecting faint analogue candidates. Aims. Our aim is to implement the methodology for identifying faint analogues at the limit of precision allowed by the current spectroscopic surveys. We quantify the precision attainable for the atmospheric parameters of effective temperature (Teff), metallicity ([Fe/H]), and surface gravity (log g) when derived from moderately low-resolution (R = 8000) spectra with S∕N ~ 100. We estimate the significance of reddening at 100–300 pc from the Sun. Methods. We used the less precise photometry in the HIPPARCOS catalogue to select potential analogues with V ~ 10.5 mag (located at ~135 pc). We calibrated Teff and [Fe/H] as functions of equivalent widths of spectral indices by means of the principal component analysis regression. We derived log g, mass, radius, and age from the atmospheric parameters, Gaia parallaxes, and evolutionary tracks. We evaluated the presence of reddening for the candidates by underestimations of photometric Teff with respect to those derived by spectral indices. These determinations were validated with extinction maps. Results. We obtained the atmospheric parameters Teff, [Fe/H], and log g with precision of 97 K, 0.06 dex, 0.05 dex, respectively. From 21 candidates analysed, we identify five solar analogues: HIP 991, HIP 5811, and HIP 69477 have solar parameters within 1σ errors, and HIP 55619 and HIP 61835 within 2σ errors. Six other stars have Teff close to solar, but slightly lower [Fe/H]. Our analogues show no evidence of reddening except for four stars, that present E(B−V) ≥ 0.06 mag, translating to at least a 200 K decrease in photometric Teff.

Breathing Crack Localization in Structures Based on Principal Component Analysis of Forced Vibration Responses

2020 ◽  
pp. 2150041
Author(s):  
J. Prawin
Keyword(s):  
Principal Component Analysis ◽  
Experimental Studies ◽  
Time History ◽  
Diagnostic Technique ◽  
Principal Component ◽  
Component Analysis ◽  
Harmonic Excitation ◽  
Crack Identification ◽  
Breathing Crack ◽  
Output Only

The identification of a breathing crack is a highly challenging inverse problem in structural health monitoring. A novel output-only damage diagnostic technique based on Principal Component Analysis (PCA) is proposed for breathing crack identification in structures excited by harmonic excitation. The proposed approach basically utilizes the residues obtained from PCA of the forced acceleration-time history responses of the structure for breathing crack identification. In this approach, the traditional single-tone, bitone and as well as multi-tone harmonic excitations are considered as input to the structure while exploring the residues of the responses for breathing crack identification. A new Damage Localization Index (DLI) based on the Fourier spectrum amplitudes of the nonlinear sensitive features (i.e. buried in residues), measured at varied locations spatially across the structure is proposed for breathing crack localization. The robustness and effectiveness of the proposed PCA-based breathing crack localization approach is verified through both numerical and experimental studies.

Scanning x-ray fluorescence microscopy and principal component analysis

1992 ◽  
Vol 50 (2) ◽  
pp. 1752-1753
Author(s):  
Brian Cross
Keyword(s):  
Principal Component Analysis ◽  
Fluorescence Microscopy ◽  
Spatial Resolution ◽  
High Speed ◽  
Image Acquisition ◽  
Principal Component ◽  
Fluorescence Microscope ◽  
Acquisition Rate ◽  
X Ray ◽  
Speed Up

A relatively new entry, in the field of microscopy, is the Scanning X-Ray Fluorescence Microscope (SXRFM). Using this type of instrument (e.g. Kevex Omicron X-ray Microprobe), one can obtain multiple elemental x-ray images, from the analysis of materials which show heterogeneity. The SXRFM obtains images by collimating an x-ray beam (e.g. 100 μm diameter), and then scanning the sample with a high-speed x-y stage. To speed up the image acquisition, data is acquired "on-the-fly" by slew-scanning the stage along the x-axis, like a TV or SEM scan. To reduce the overhead from "fly-back," the images can be acquired by bi-directional scanning of the x-axis. This results in very little overhead with the re-positioning of the sample stage. The image acquisition rate is dominated by the x-ray acquisition rate. Therefore, the total x-ray image acquisition rate, using the SXRFM, is very comparable to an SEM. Although the x-ray spatial resolution of the SXRFM is worse than an SEM (say 100 vs. 2 μm), there are several other advantages.

A German version of the Intermittent Claudication Questionnaire (ICQ): cultural adaptation and validation

VASA ◽  
2012 ◽  
Vol 41 (5) ◽  
pp. 333-342 ◽  
Author(s):  
Kirchberger ◽  
Finger ◽  
Müller-Bühl
Keyword(s):  
Principal Component Analysis ◽  
Intermittent Claudication ◽  
Completion Time ◽  
Short Form ◽  
Principal Component ◽  
Component Analysis ◽  
German Version ◽  
Average Completion Time ◽  
Sf 36 ◽  
Related Quality

Background: The Intermittent Claudication Questionnaire (ICQ) is a short questionnaire for the assessment of health-related quality of life (HRQOL) in patients with intermittent claudication (IC). The objective of this study was to translate the ICQ into German and to investigate the psychometric properties of the German ICQ version in patients with IC. Patients and methods: The original English version was translated using a forward-backward method. The resulting German version was reviewed by the author of the original version and an experienced clinician. Finally, it was tested for clarity with 5 German patients with IC. A sample of 81 patients were administered the German ICQ. The sample consisted of 58.0 % male patients with a median age of 71 years and a median IC duration of 36 months. Test of feasibility included completeness of questionnaires, completion time, and ratings of clarity, length and relevance. Reliability was assessed through a retest in 13 patients at 14 days, and analysis of Cronbach’s alpha for internal consistency. Construct validity was investigated using principal component analysis. Concurrent validity was assessed by correlating the ICQ scores with the Short Form 36 Health Survey (SF-36) as well as clinical measures. Results: The ICQ was completely filled in by 73 subjects (90.1 %) with an average completion time of 6.3 minutes. Cronbach’s alpha coefficient reached 0.75. Intra-class correlation for test-retest reliability was r = 0.88. Principal component analysis resulted in a 3 factor solution. The first factor explained 51.5 of the total variation and all items had loadings of at least 0.65 on it. The ICQ was significantly associated with the SF-36 and treadmill-walking distances whereas no association was found for resting ABPI. Conclusions: The German version of the ICQ demonstrated good feasibility, satisfactory reliability and good validity. Responsiveness should be investigated in further validation studies.

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