Search results for "Insula"
showing 10 items of 735 documents
Euphorbio meuselii-Rubetum ulmifolii, a new name for a Sicilian association of brambles
2018
Palabras clave: Nomenclatura, sintaxonomía, zarzales, Sicilia, Península Ibérica.Key words: Nomenclature, Syntaxonomy, brambles, Sicily, Iberian Peninsula.
Metal-Insulator Transition of Solid Hydrogen by the Antisymmetric Shadow Wave Function
2016
We revisit the pressure-induced metal-insulator-transition of solid hydrogen by means of variational quantum Monte Carlo simulations based on the antisymmetric shadow wave function. In order to facilitate studying the electronic structure of large-scale fermionic systems, the shadow wave function formalism is extended by a series of technical improvements, such as a revised optimization method for the employed shadow wave function and an enhanced treatment of periodic systems with long-range interactions. It is found that the superior accuracy of the antisymmetric shadow wave function results in a significantly increased transition pressure.
Osgillazioni eustatiche, biocronologia dei depositi continentali quaternari e neotettonica nella Sicilia nord-occidentale (penisola di San Vito lo Ca…
1999
Vengono presentati i risultati di uno studio interdisciplinare condotto nella Penisola di San Vito lo Capo, Sicilia nord - occidentale. In questa area i terreni quaternari sono rappresentati da depositi marini e di spiaggia distribuiti a varie quote e da depositi continentali contenenti resti di vertebrati. Questi terreni si rinvengono all'interno di solchi e grotte marine, dove sono state riconosciute anche fasce a fori di litodomi, o costituiscono corpi sedimentari che giacciono sopra superfici di abrasione marina. Le associazioni a mammiferi presenti in tali terreni appartengono al complesso faunistico a Elephas falconeri del primo Pleistocene medio, al complesso a Elephas mnaidriensis d…
Design, build-up and optimization of a fast quenching device for polymeric thin film
2014
In this work an innovative apparatus for the characterization of polymer solidification under very high cooling rates (up to thousand of K/s) is described, according to the continuous cooling transformation approach adopted in metallurgy for studying structure development in metals. The proposed model experiment is addressed to design a method for the characterization of non-isothermal solidification behaviour, encompassing typical cooling conditions of polymer processing. Only temperature history determines the structure formed, as melt solidification takes place in quiescent conditions. With respect to the device previously developed by the authors [1, 3] the present equipment presents th…
Rapid shifting of a deep magmatic source at Fagradalsfjall volcano, Iceland
2022
AbstractRecent Icelandic rifting events have illuminated the roles of centralized crustal magma reservoirs and lateral magma transport1–4, important characteristics of mid-ocean ridge magmatism1,5. A consequence of such shallow crustal processing of magmas4,5 is the overprinting of signatures that trace the origin, evolution and transport of melts in the uppermost mantle and lowermost crust6,7. Here we present unique insights into processes occurring in this zone from integrated petrologic and geochemical studies of the 2021 Fagradalsfjall eruption on the Reykjanes Peninsula in Iceland. Geochemical analyses of basalts erupted during the first 50 days of the eruption, combined with associate…
Raman Scattering Applied to Materials Science
2015
Abstract One of the most powerful techniques to extract physical and chemical information of a material is the light scattering. Opposite to x-ray scattering for instance, where an average of the sample properties is obtained, Raman scattering is a local probe which can be used to detect inhomogeneities, local strain, lack of crystallinity, anharmonicities or information on the electronic structure by means of resonant Raman scattering. In this work, we will analyze the main contributions of Raman scattering in Materials Sciences. After a brief introduction of the technique and the equipment needed for the physical measurements, we will give practical examples of Raman scattering measuremen…
Selective quantification of humidity and ammonia by optical excitation of molecular semiconductor-doped insulator (MSDI) sensors
2015
MSDI (molecular semiconductor-doped insulator) ammonia sensors have been investigated using cyclic optical excitation as multi-signal generation method. This method enables a selective quantification of both humidity in the range of 30–70 %rh and ammonia concentration in the range of 0–30 ppm with a single sensor at room temperature.
The reinterpretation of Cova Negra archaeological and stratigraphical sequence and its implications in the knowledge of the Middle Palaeolithic Iberi…
2020
This paper presents new data from the reinterpretation of the Cova Negra sequence from a chronological and stratigraphic perspective. The primary aim is to reorder the lithic industry from the excavations of the 1950s in light of the stratigraphic sequence, paying particular attention to raw materials, knapping methods and tools. The reconstruction, carried out from a taphonomic perspective, is specified in sectors B, C and F, and the archaeological levels and the included material are adjusted to the stratigraphic levels. Although the number of remains involved in the proposed chronology is reduced in relation to previous work, it is an arrangement that relies on a more precise chronostrat…
Model of ageing inception and growth from microvoids in polyethylene-based materials under AC voltage
2008
Several degradation mechanisms may affect polymeric insulation system reliability. Some authors postulate that, even in a perfect dielectric, nanoscale cavities can enlarge due to various mechanisms (from mechanical fatigue to lowering of the degradation reaction energy barrier) up to a point where highly energetic phenomena, which bring about breakdown, can be incepted. Other authors are more focused on the inherent limits of manufacturing processes, which leave cavities within the insulation system whose size is large enough to cause electron avalanches, thus a measurable partial discharge (PD) activity, from the time the system is put in service or as a function of external factors (e.g.…
Fracture Toughness of PIR Foams Produced from Renewable Resources
2012
Rigid low-density closed-cell polyisocyanurate (PIR) foams are used primarily as a thermal insulation material. Traditionally, they are manufactured from constituents produced by petrochemical industry. Introducing renewable materials in PIR formulation brings definite economical and environmental benefits. Fracture toughness of PIR foams obtained from renewable resources (with the polyol system comprising up to 80% of rapeseed oil esters) and petrochemical PIR foams has been characterized experimentally, by compact tension tests, for mode I crack propagation along the rise direction of the foams.