1,720,958 research outputs found
LED Applications in Railway Signals: Wavelength and Intensity vs Temperature Variation
No full textIn recent years, light emitting diodes (LEDs) have entered the lighting market, offering consumers performance and features exceeding those of traditional lighting technologies. LEDs (light-emitting diodes) are becoming more common in safety signals for railroad, highway, automotive, and many other applications. In addition to having a longer life and greater durability than incandescent bulbs, LEDs are much more energy efficient than their incandescent counterparts. Since the heat from the junction must be dissipated into the ambient somehow, changing the ambient temperature af-fects the junction temperature and hence the emitted light. When the LEDs are used in the railway or traffic signals, the optical proprieties of these have to maintain more rigorous specifications. Therefore the development of signals using LED as light source, able to respect intensity specifications, is not simple. In this paper, we describe problems of the temperature dependent changes of LED intensity and color shift. Besides we will introduce an innovative technique, that we have developed, to allow the use of the LEDs in applications with rigorous specifications
Application of LEDs to traffic signal
No full textThe new traffic lights, you are seeing, are made out of arrays of light emitting diodes (LEDs). These are tiny, purely electronic lights that are extremely energy efficient and have a very long life. In this paper we present this new technology that is spreading further into niche solutions such as traffic signals. In particular we will focus on critical issues, due to the dependence of their opto-electronic characteristics by temperature that currently limit their use, defining a possible solution to this problem
“Vaporetto” Lacustre VERDE: imbarcazione ad impatto ZERO
No full textL’inquinamento dell’acqua è tra i vari tipi di alterazione ambientale (dell’aria, del suolo, da rumore, alimentare, ecc.) quello che desta la maggiore, anche se non esclusiva, preoccupazione nell’opinione pubblica.
Il lago Paola (o di Sabaudia) presenta acque “abbastanza” inquinate. Ciò nonostante sono in atto tutta una serie di contenziosi legali atti a rendere inapplicabili le direttive della Comunità Europea e del Comune che recentemente hanno stabilito che la navigazione è interdetta a mezzi che fanno uso di trazione derivante dall’uso di motori a combustione interna.
Per evitare danni economici, derivanti dalla limitazione della fruizione turistica e sportiva del lago, il presente progetto propone un sistema in grado di garantire il pieno godimento del Lago nel rispetto delle direttive di protezione ambientale.
Partendo dalla progettazione di uno scafo innovativo che minimizzi la resistenza all’avanzamento, è stato progettato un “sistema” per navigazione lacustre con imbarcazione a propulsione “esclusivamente” elettrica con energia ricavata da fonti rinnovabili (campo fotovoltaico). Il sistema proposto consente di navigare con “minimo” impatto sull’habitat del territorio su cui si insiste (fondamentale nei parchi nazionali)
Simple educational tool for digital speckle shearography
No full textIn this study, an educational tool has been prepared for obtaining short-term and more economic training on digital speckle shearography (DSS). Shearography non-destructive testing (NDT) has gained wide acceptance over the last decade, providing a number of important and exciting inspection solutions in aerospace, electronics and medical device manufacturing. For exploring these motivations, it is important to develop didactic tools to understand the potential of digital shearography through training and didactic courses in the field of NDT. In this paper we describe a simple tool for making one familiar with the potential of DSS in the area of education and training. The system is realized with a simple and economic optical setup and a virtual instrument based on the LabVIEW and DAQ
Light emitting diode in stationary transportation applications: wavelength response to varying temperature
No full textIn recent times, the transportation industry has generated a number of developments involving new technology in signaling. Important developments have involved the production of light by means of light emitting diode (LED). The optical proprieties of LEDs depended on junction temperature. Since the heat from the junction must be dissipated into the ambient somehow, changing the ambient temperature affects the junction temperature and hence the emitted light. When the LEDs have been used in the railway or traffic signals, the optical proprieties of these have to maintain more rigorous color specifications. Besides, the limits imposed must be respected in ample range of variation of the ambient temperature (typ. 233-347K). The peak wavelength of LED shifts proportionally to changes in junction temperature. Therefore, to respect color specifications with signals using LED as light source it is not simple. In this paper, we describe problems of the temperature dependent changes of colorimetrical parameters of LEDs. Besides we will introduce a method through which to build a correct signal with feedback that, according to the measured temperature, it reacts to correct the optic characteristics of signal
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
Variations on the Author
Get PDF“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
Get PDFWe 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
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