Search results for " light"
showing 10 items of 1141 documents
Effects of InAlN underlayer on deep traps detected in near-UV InGaN/GaN single quantum well light-emitting diodes
2019
Two types of near-UV light-emitting diodes (LEDs) with an InGaN/GaN single quantum well (QW) differing only in the presence or absence of an underlayer (UL) consisting of an InAlN/GaN superlattice (SL) were examined. The InAlN-based ULs were previously shown to dramatically improve internal quantum efficiency of near-UV LEDs, via a decrease in the density of deep traps responsible for nonradiative recombination in the QW region. The main differences between samples with and without UL were (a) a higher compensation of Mg acceptors in the p-GaN:Mg contact layer of the sample without UL, which correlates with the presence of traps with an activation energy of 0.06 eV in the QW region, (b) the…
An Energy-Autonomous Wireless Sensor with Simultaneous Energy Harvesting and Ambient Light Sensing
2021
Wireless sensor nodes (WSNs) are generally powered by batteries, which results in a substantial limitation to the places where the nodes can be installed, to the maximum number of deployable devices, and to the node lifetime. To meet the demand for Internet-of-Things (IoT) applications that require a large number of maintenance-free, low cost, wireless sensor nodes, this paper proposes a wireless sensor platform with a single photovoltaic transducer that performs the dual role of harvesting energy and sensing ambient light. This dual use allows even smaller and cheaper nodes that do not require any form of supporting external power, with a reduced component count. The device implements off-…
Improving nanoscale terahertz field localization by means of sharply tapered resonant nanoantennas
2020
Abstract Terahertz resonant nanoantennas have recently become a key tool to investigate otherwise inaccessible interactions of such long-wavelength radiation with nano-matter. Because of their high-aspect-ratio rod-shaped geometry, resonant nanoantennas suffer from severe loss, which ultimately limits their field localization performance. Here we show, via a quasi-analytical model, numerical simulations, and experimental evidence, that a proper tapering of such nanostructures relaxes their overall loss, leading to an augmented local field enhancement and a significantly reduced resonator mode volume. Our findings, which can also be extended to more complex geometries and higher frequencies,…
TAPERING RESONANT NANOANTENNAS FOR ENHANCED THz LIGHT – NANOMATTER INTERACTIONS
2020
Nel corso degli ultimi decenni la tecnologia terahertz (THz) è diventata un fruttuoso campo di ricerca grazie alla spinta ricevuta dal desiderio di sfruttarne le promettenti applicazioni in questa porzione dello spettro elettromagnetico. La biologia, la medicina e l’ingegneria sono soltanto alcuni dei settori che guardano con interesse alle ultime scoperte nella ricerca sulle onde THz. Questo enorme interesse nasce dalle peculiari proprietà di tali onde, come ad esempio: il carattere non ionizzante, l’opacità di svariati materiali solitamente trasparenti in altri intervalli di frequenze e per le potenziali ricadute positive nel campo della tecnologia dell’informazione. Una fra le applicazio…
Multiband variability studies and novel broadband SED modeling of Mrk 501 in 2009
2017
Astronomy and astrophysics 603, A31 (2017). doi:10.1051/0004-6361/201629540
Facciate di luce: nuovi scenari urbani … verso una luminosa forma partecipativa
2011
Dopo una breve sequenza di tappe storiche, nel corso del XX secolo, che segna alcuni passaggi significativi nell’evoluzione del progetto luminoso applicato alla facciata degli edifici, la ricerca focalizza l’attenzione su intenzionalità, strumentazioni, intenti comunicativi e di spettacolarità di alcuni interventi a carattere artistico realizzati nell’ultimo trentennio (dagli anni ‘80 a oggi), che individuano modificazioni figurative, funzionali e di significato della facciata degli edifici e con essa di un nuovo paesaggio urbano notturno. Grazie all’avanzamento tecnico-tecnologico che realizza la rivoluzione digitale, la facciata luminosa sostituisce o talora affianca alle componenti comm…
Marx y Engels y la división sexual del trabajo en la familia: ambigüedades, equívocos y vacíos teóricos
2018
Dada la importante influencia de Marx y Engels en el análisis de la estructura social, no sorprende el notable impacto de su obra en el estudio del papel de la mujer en la familia. Sin embargo, su herencia en este ámbito sociológico ha dado lugar a interpretaciones muy polarizadas. Este artículo quiere aportar algo de luz evidenciando las contradicciones del marxismo al estudiar el papel de la mujer en la familia. Para ello se comparan las contribuciones de Marx y Engels para calibrar posibles diferencias en las posturas de dos autores que en otros ámbitos han presentado un pensamiento muy homogéneo. Los resultados obtenidos permiten afirmar que, a pesar de su innegable influencia en el pen…
Protection of Trees against Lightning Strikes as a Measure to Prevent Fires and Loss of Human Life
2021
Lighting strikes have been the catalyst of massive uncontrolled fires in areas of combustible vegetation. In some regions, lightning strikes may be a relatively unusual occurrence (e.g., California), but instead they seem to have become a major contributor to the propagation of wildfires, as a byproduct of climate change. Given such unusual weather, wildfires originating from lightning are an increasing threat. In this paper, the authors discuss the withstand capability of trees against lightning and introduce a proactive approach to prevent wildfires by the deployment of tree lighting protection systems (TLPS) to protect forested areas, where deemed necessary by the tree risk assessment.
Light hydrocarbons as a proxy to identify the origin of the gas manifestations in Greece
2017
The geologic emissions of greenhouse gases (CO2 and CH4) have an important natural contribution in the global carbon budget. Tectonics, through faults in geothermal and oil producing areas, play a significant role in the release of C-gases in many non-volcanic regions of the Earth. Methane, the most abundant organic compound in Earth’s atmosphere, has a potential global warming that is 28 times higher than that of CO2 on a 100-year time horizon. In this study, δ13C-CH4, δ2H-CH4 and light hydrocarbon (alkane: CH4, C2H6, C3H8, C3H6, i-C4H10, n-C4H10; alkene C3H6, iC4H8; and aromatic C6H6) gas concentration data of 119 gas samples (103 unpublished data and 16 literature data) from volcanic-hyd…
Mineralogy of the soils altered by fumarolic activity at Nisyros volcano, Greece
2017
Nisyros is the easternmost island of the South Aegean Active Volcanic arc in Greece. It is an active stratovolcano known for its intense hydrothermal activity. In this study we present the results of the mineralogical analyses of 20 soil samples collected in the caldera area. Samples were analysed through X-ray diffraction and the results allow us to divide them in two groups: Lakki Plain and Stefanos Crater. In their majority the soils of Lakki Plain have a main mineralogical assemblage that consists of quartz, feldspar and gismondine (Ca2Al4Si4O16·9H2O). Gismondine as well as stellerite (CaAl2Si7O18·7H2O), which is appearing in some samples, derive from hydrothermal alteration, whilst wol…