1,721,019 research outputs found
Schede Arduino e sensori di luce. Risultato dei test e realizzazione di uno strumento di misura
Get PDFLe schede elettroniche denominate “Arduino” rappresentano una soluzione semplice, a basso costo ed estremamente versatile, che consente di realizzare strumentazione da laboratorio utile sia per la misura di diverse grandezze fisiche sia per l’automazione di alcuni processi. In questo Rapporto Tecnico verrà dapprima esposta una panoramica delle potenzialità di tali schede, insieme ad una serie di esperimenti in cui sono stati usati con successo degli strumenti fatti ad hoc, per poi passare alla descrizione dell’interfacciamento di Arduino con misuratori di luce a molti sensori. Tali sensori possono essere in configurazione lineare (array) o a matrice (fotocamere di tipo CCD o CMOS) e sono dotati di decine, centinaia o anche migliaia di microelementi di dimensioni che vanno da pochi micron a qualche decina di micron. La gestione e la manipolazione di questi sensori richiede un’elettronica particolarmente accurata nei tempi, poiché funzionano grazie ad impulsi regolari inviati loro dall’esterno, ed una capacità di digitalizzazione ed archiviazione dei segnali di tensione che deve avvenire in modo accurato e veloce. Infine, sarà illustrato uno strumento di misura completo, realizzato con una di tali schede, in grado di replicare con successo la bussola solare recentemente brevettata dall’ENEA.The electronic boards known as "Arduino" represent a simple, low cost and extremely versatile solu- tion, which allows to realize laboratory instrumentation useful both for the measurement of many phy- sical quantities and for the automation of some processes. In this Technical Report, an overview of the potentiality of these boards will first be presented, together with a series of experiments in which some tools have been successfully used, to move on to the description of the interfacing of Arduino with light multi-sensors. These sensors can be in linear (array) or matrix (CCD or CMOS type cameras) configuration and are equipped with tens, hundreds or even thousands of microelements whose size ranges from a few microns to a few tens of microns. The ma- nagement and manipulation of these sensors requires electronics that have high time accuracy, since they work thanks to regular pulses sent by an external source, and a capacity to digitize and store vol- tage signals that must be carried out accurately and quickly. Finally, a complete measuring instrument will be shown, made with one of these cards, capable of suc- cessfully replicating the solar compass recently patented by ENEA
Pattern recognition after image processing of low-contrast images, the case of the Shroud of Turin
No full textWe discuss the potentially misleading effect of software techniques for elaborating low-contrast images. In particular, we present the example of the stains embedded into one of the most studied archeological objects in history, the Shroud of Turin. We show for the first time that image processing of both old and recent photographs of the Shroud may lead some researchers to perceive inscriptions and patterns that do not actually exist, confirming that there is a narrow boundary between image enhancement and manipulation. © 2012 Elsevier Ltd. All rights reserved
Investigating the color of the blood stains on archaeological cloths: the case of the Shroud of Turin
No full textThe unique reddish blood stains on the archaeological cloth known as the Shroud of Turin caught the attention of several scholars, who proposed different hypotheses to explain the unusual blood color. To date, just a few hypotheses have been tested experimentally, and the results are debatable. In this paper, we test the strength of two hypotheses (namely, the presence of carboxyhemoglobin and the long-term influence of ultraviolet light on high-bilirubin blood) by the spectral reflectance of the blood stained regions on the Shroud and by color analyses of ultraviolet irradiated high-bilirubin blood stains on linen. The relevance of these simple methods to the study of stained textiles is discussed. © 2018 Optical Society of America
Influence of ultraviolet radiation on the color of blood stains embedded in the archaeological textile known as the Shroud of Turin
No full textThe archaeological cloth known as the Shroud of Turin is a controversial object for both scientific and religious reasons. After a brief introduction on the scientific data about the age of the cloth and the microscopic complexity of the images embedded on it, we discuss the unique reddish color of blood stains on the Shroud, which caught the attention of several scholars in the last decades. Various hypotheses were proposed to explain the blood stains reddish color, and the experimental tests produced uncertain results because data were not sufficient or were obtained in vitro. We have tested the strength of two hypotheses, namely, the long term influence of ultraviolet (UV) light on high-bilirubin blood and the presence of carboxyhemoglobin, respectively by RGB color analyses of high-bilirubin blood after irradiation by ns excimer laser pulses and UV lamp and by the study of the spectral reflectance of the blood stains on the Shroud. © 2019 SPIE
Analytical treatment and experiments of the virtual image of cone mirrors
No full textWe present the analytical calculation, validated by experiments, of the virtual image of solid cone mirrors used to decipher hidden pictures and/or writings on the plane of the cone’s base. Our results demonstrate that the virtual image of solid cone mirrors lies on a not intuitive 3D surface, thus showing how the commonly used geometric treatment is inadequate to find the correct position of the virtual image. The extension of our analysis to cone mirrors used as panoramic imaging tools for machine vision is discussed
The interdisciplinary nature of anamorphic images in a journey through art, history and geometry
No full textAnamorphosis is a procedure for drawing an image that appears distorted and indecipherable when seen frontally, the image becoming intelligible only from an eccentric viewpoint or when reflected by a properly designed mirror. In this paper we propose a journey through figurative art, history, psycho-perception and geometry, including a mathematical proof regarding the position of the observation point of anamorphoses. Finally, we discuss applications of anamorphic techniques in encryption, counterterrorism, street art and advertising. Most matter proposed in this paper is suitable for arts educators and offers an interdisciplinary approach to anamorphoses by a creative interaction between different topics, like psychology and figurative arts, geometry and advertising, street art and mathematics
Le immagini anamorfiche in un viaggio interdisciplinare tra arte, storia, geometria e attualità
Get PDFL’anamorfosi è la tecnica di disegnare un’immagine deforme, incomprensibile se vista frontalmente, che appare ben proporzionata da un punto di vista eccentrico, oppure osservando il suo riflesso da un opportuno specchio curvo. Nel saggio viene proposto un affascinante viaggio fra immagini virtuali, metafore visive e inganni prospettici, riassumendo l’origine, i protagonisti e le tecniche per costruire diversi tipi di anamorfosi. Si incontrano quesiti di psicologia della percezione, di geometria, di storia dell’arte, di prospettiva e di fisiologia della visione. Gli appassionati di matematica possono soffermarsi sui calcoli analitici della mappatura dei disegni anamorfici prospettici e catottrici conici e della posizione del punto di osservazione delle anamorfosi prospettiche. Infine, sono descritte alcune tecniche anamorfiche applicate alla crittografia, all’antiterrorismo, alla pubblicità, alla paesaggistica, all’arte di strada e alla didattica.
Il saggio presenta un approccio multidisciplinare al tema dell’anamorfismo, evidenziando una sorprendente interazione tra argomenti apparentemente distanti, come la geometria e la psicologia, l’ottica e la prospettiva, l’arte di strada e la fisiologia della visione. Lo studio interdisciplinare delle anamorfosi, oltre ad essere facilmente adattabile a scopi didattici e divulgativi, può rappresentare un ponte tra le culture umanistica e scientifica, in un raro esempio di Cultura Totale
Analysis of high-n dielectronic Rydberg satellites in the spectra of Na-like Zn XX and Mg-like Zn XIX
No full textWe have observed spectra from highly charged zinc ions in a variety of laser-produced plasmas. Spectral features that are Na- and Mg-like satellites to high-n Rydberg transitions in the Ne-like Zn XXI spectrum are analyzed and modeled. Identifications and analysis are made by comparison with highly accurate atomic structure calculations and steady state collisional-radiative models. Each observed Zn XX and Zn XIX feature comprises up to ≈ 2 dozen individual transitions, these transitions are excited principally by dielectronic recombination through autoionizing levels in Na- and Mg-like Zn19+ and Zn18+. We find these satellites to be ubiquitous in laser-produced plasmas formed by lasers with pulse lengths that span four orders of magnitude, from 1ps to ≈ 10 ns. The diagnostic potential of these Rydberg satellite lines is demonstrated. © 2004 The American Physical Society
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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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