1,720,975 research outputs found
Asbestos detection in construction and demolition waste adopting different classification approaches based on short wave infrared hyperspectral imaging
No full textAsbestos has been widely used in many applications for its technical properties (i.e. resistance to abrasion, heat and chemicals). Despite its properties, asbestos is recognized as a hazardous material to human health. In this paper a study, based on multivariate analysis, was carried out to verify the possibilities to utilize the hyperspectral imaging (HSI), working in the short-wave infrared range (SWIR: 1000-2500 nm), to detect the presence of asbestos-containing materials (ACM) in construction and demolition waste (CDW). Multivariate classification methods including classification and regression tree (CART), partial least squares-discriminant analysis (PLSDA) and correcting output coding with support vector machines (ECOC-SVM), were adopted to perform the recognition/classification of ACM in respect of the other fibrous panels not containing asbestos, in order to verify and compare Efficiency and robustness of the classifiers. The correctness of classification results was confirmed by micro-X-ray fluorescence maps. The results demonstrate as SWIR technology, coupled with multivariate analysis modeling, is a quite promising approach to develop both "off-line" and "on-line" fast reliable and robust quality control strategies, finalized to perform a first evaluation of the presence of ACM
Analisi e gestione dei suoli contaminati da amianto
No full textLa gestione dei suoli contaminati da amianto rappresenta una tematica di interesse dal punto di vista dei possibili rischi per la salute degli operatori e della popolazione residente nelle aree limitrofe ai luoghi in cui tali suoli sono presenti. Il presente fact sheet, incentrato sui metodi analitici tradizionali ed innovativi per l’analisi dei suoli contenenti amianto, rappresenta uno strumento utile innanzitutto per gli addetti al campionamento ed alle analisi di laboratorio, ma anche per gli altri operatori addetti alla gestione di tali suoli e gli amministratori locali e i cittadini che vogliono informarsi su tale problematica
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Chrysotile detection in soils with proximal hyperspectral sensing and chemometrics
Full text linkIn this work the authors present an innovative methodology, based on proximal hyperspectral sensing and chemometric techniques, aimed at detecting asbestos containing soils. Short Wave InfraRed (SWIR) reflectance spectra of reference samples containing known chrysotile fractions were collected in laboratory. Since the identification of asbestos containing soils depends on the contaminant mass percentage (weight/weight), two supervised multivariate data projection methods were evaluated for asbestos concentration prediction. The first results are reported here, together with advantages and limits of the analytical methods. Orthogonal Partial Least Squares (PLS) regression showed the lowest error in prediction and the highest coefficient of determination in prediction. This technique would support screening activities frequently conducted during environmental assessment and remediation projects
Scanning electron microscopy and hyperspectral imaging in man made vitreous fibers characterization
No full textFibers can be classified into natural and man-made (i.e., synthetic) fibers, further categorized as organic or inorganic. Man-made vitreous fibers (MMVFs) are non-crystalline, fibrous inorganic substances (silicates) primarily made from rock, glass or processed minerals. This group includes glass fibers (i.e., glass wool or continuous glass filament), rock (stone)/slag wool and refractory ceramic fibers.
A fiber is defined as a particle with a length to width ratio of at least 3:1. MMVFs can be classified as non-hazardous or hazardous based on their chemical and geometric characteristics (i.e., inhalable/respirable). Respirable fiber have a diameter (FD) < 3 μm, length (FL) > 5 μm and a length to width ratio (FL/FD) > 3:1, capable of reaching the deepest part of the lung.
The most commonly used analytical techniques to date are the same as those used for asbestos fibers.
Scanning Electron Microscopy (SEM) is a powerful imaging technique using an electron beam to illuminate a sample, producing high-resolution images. It enables detailed visualization of MMVF individual fibers, allowing to analyze their morphology, size distribution, structure, aspect ratio and surface features. SEM, when equipped with energy-dispersive X-ray spectroscopy (EDS), can also determine the elemental composition of MMVFs, thus aiding in understanding their chemical makeup and potential environmental impact.
Hyperspectral Imaging (HSI) is a non-destructive imaging technique that combines conventional imaging with spectroscopy, not requiring any physical or chemical samples manipulation. It captures images of a sample, at multiple wavelengths, across the electromagnetic spectrum, providing detailed spectral information for each pixel. HSI facilitates a rapid and accurate identification and analysis of different components in MMVF samples, based on their spectral signatures. It can also generate spatial maps of MMVF distribution, providing insights into fiber dispersion within a material or product. Additionally, HSI offers information about the size, shape and orientation, assisting in their characterization.
Both SEM and HSI are valuable techniques for studying MMVFs. SEM provides detailed structural and elemental information at the micro and nanoscale, while the most diffused HSI devices operating at lab and micro scale offer information about fiber distribution and characteristics based on detected spectral signatures with a maximum spatial resolution of the order of microns. However, SEM requires complex sample preparation (similar to other “standard” fiber analysis techniques such as Fourier-transform infrared spectroscopy (FTIR), XRay Diffraction (XRD) and Optical Microscopy), and longer analysis time. These drawbacks can expose operators to risks and contaminate the laboratory. In contrast, HSI does not require sample preparation, reducing both analysis time and exposure risks.
The study shows the morphological and compositional differences of several MMVF samples, by SEM-HSI combined analysis. The results can contribute to a more accurate and rapid characterization of fibers, especially regarding their potential hazards to humans and the environment. The goal is to achieve a reliable, robust and fast analysis using HSI alone, without the need for SEM or preparative operations, as required by traditional techniques
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