1,721,102 research outputs found
Raman Spectroscopy for Temporally Resolved Combustion Gas Diagnostics
No full text: A novel approach for cost-effective and temporally resolved in-line combustion gas diagnostics based on spontaneous Stokes Raman spectroscopy is presented in this paper. The proposed instrument uses a multipass configuration designed to increase the scattering generation, giving information about gas species concentrations, including H2 and N2 that are not commonly available from analysis with absorption spectroscopy techniques. The system performs calibrated analysis providing both qualitative and quantitative information about the gas composition. Depending on the application, the device can work with spectra integration time from 0.15 s up to 10 s, with a Raman spectrum ranging from the H2 rotational peak at Raman shift of 587 cm-1 up to the H2 vibrational peak at 4156 cm-1, covering all the Raman emissions of major combustion species. The device response was characterized by a working pressure from 0.7 to 7.5 bar. The instrument prototype has been made completely transportable, designed to operate using a gas sampling system, and ready to be operated in relevant industrial in-line environments
X-ray shape-from-silhouette for three-dimensional modelling applied to ancient metallic handworks
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Compression of Extreme-Ultraviolet Ultrashort Pulses by Grating Configurations
Full text linkThe design and realization of grating instruments to condition the spectral phase of ultrashort extreme-ultraviolet pulses are discussed. The main application of such configurations is the temporal compression of pulses by compensating the phase chirp and getting close to the Fourier limit. We discuss the two configurations useful for the realization of ultrafast grating compressors, namely, the classical diffraction mount and the off-plane one. The configuration may be applied to free-electron lasers and high-order laser harmonics
Multipass Raman spectroscopy applied to qualitative and quantitative combustion gas diagnostic
No full textThis paper introduces a novel laser-based system designed for real-time Raman spectroscopy applied to in-line combustion diagnostics. While Raman spectroscopy is a well-established technique for solid and liquid analysis, its application to gas samples is challenging due to their low density, which limits the intensity of Raman scattering. To address this issue, our system utilizes a multipass cell, strategically designed to enhance signal generation and its collection. The instrument performs calibrated analysis, providing qualitative and quantitative information about gas composition. Depending by the application, the system can work with spectra integration time ranging from 0.15 s up to 10 s. This study has demonstrated that Raman spectroscopy can be a useful tool for combustion diagnostics, as it can operate fast enough to follow the time scale of combustion phenomena
Multispectral Acquisition of Large-Sized Pictorial Surfaces
No full textMultispectral acquisition of artworks has recently received considerable attention in the image processing community. Quite understandably, so far this attention has mainly focused on paintings, given their predominant role in museum collections. It is worth pointing out that the instrumentation and procedures used for acquiring regular paintings are not suited for the multispectral acquisition of large-sized painted surfaces such as frescoed halls and great paintings. Given the relevance of such artifacts, and their widespread presence in churches or historical buildings due to their social function, the problem of finding suitable techniques for their acquisition is certainly worth addressing. This paper focuses on multispectral acquisition of large-sized pictorial surfaces, systematically addressing the practical issues related to the acquisition equipment and procedure. Given the crucial role played by the illumination in this application, special attention is given to this issue. The proposed approach is supported by experimental results
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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