1,721,057 research outputs found
Trace element analysis of archaeological glasses: comparison between LA-ICPMS and Electron Microprobe analysis.
No full textRiassunto presentato al Congresso congiunto SIMP-AIV-SoGeI-SGI "Il Pianeta Dinamico: sviluppi e prospettive a 100 anni da Wegener", Firenze, 2-4 Settembre 2015
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
A novel Retrofittable Solar Cooler/Heater based on Adsorption cycle for domestic application
No full textSolar driven cooling machines have been employed until recent years only in niche markets due to a series of reasons: dimensions of the machines, cooling power storage, production costs, and others.
At present times there's a high request for a reliable technology developed for domestic applications at distributed level. The solar heating is a rapidly growing market and the available technologies are almost consolidated, but a strong limitation to the application of solar collectors is due to the waste heat available in summer periods, which limit the sizing of solar domestic installations, limit the capacity to provide not only support to hot sanitary water, but even to indoor space heating. The objective of the present work is to suggest a possible solution and try to give a contribution to the described problem. The R&D performed at FBK-REET labs has produced a new concept of solar driven cooling/heating machine based on a double adsorption/desorption cycle acting between two small tanks. The machine, working cyclically between desorption and adsorption, is provided of an heat storage to separate the cooling energy availability from the solar radiation. Thus the system is able to provide not only cooling power in hot periods, but even heating in colder times or for hot sanitary water production. The system may be scaled up or down in cooling capacity, sizing properly the porous adsorbing material volumes, and in cooling power, changing the air mass flow through the system. A prototype has been built, provided of a cooling capacity of about 25 kWhth and a cooling power retrofittable until a max of 4 kWth in the range of cold temperatures of about 8-12°C. The overall COP is in the range of 0,6-0,7. The system is patent pending (Publication number: WO2008099262)
LAM U-Pb zircon Early Jurassic exhumation age of the Finero Phlogopite Peridotite (Ivrea-Verbano Zone, Western Alps) and its geodynamic consequences
No full textA new LA-ICP-HRMS investigation of transparent zircons, unzoned and smoky at cathodoluminescence (CL), separated from chromitite layers segregated in mantle dunite bodies belonging to the Phlogopite Peridotite unit (hereafter PP) of the Finero Complex (Ivrea –Verbano Zone, Southern Alps) provides single-spot 206Pb/238U Lower Jurassic ages between 200 to 180 Ma, with a pronounced peak at around 190 Ma. Relevant exception is represented by two pinky zircons showing relics of zoning at CL, with darker cores that give Triassic ages from 240 to 230 Ma. The presence of continental crust component(s) evidenced by the negative EpsilonHf of the zircons, the strict similarity of the trace element contents shown by clinopyroxenes and amphiboles from chromitites and the phlogopite harzburgites and pyroxenites hosting the dunite bodies, as well as the complete to partial disappearance of olivine replaced by orthopyroxene, indicate that the parent melts of the chromitites had a cognate origin with the hydrous LILE-enriched silica-saturated melts responsible of the pervasive metasomatism recorded by the Finero mantle sequence. The combination of our data with those reported in literature for the PP chromitite zircons determines a large age interval ranging from 290 to 180 Ma. However, zircon populations with different U-Pb ages show EpsilonHf very similar to that found in this study. The latter evidence, together with the rejuvenation of the ages with the disappearing of the internal structures suggest that the large age variability is the result of a prolonged residence at mantle/lower crustal depths of the PP, characterised by progressive reequilibration stages of the U-Pb zircon system. Thus, it is here proposed that the segregation of the zircon-bearing chromitite layers was related to the pervasive metasomatic event, which occurred at ~290 Ma or before. Successively, the U-Pb zircon system remained virtually unperturbed until Middle Triassic,when the area was affected by at least two main magmatic cycles with tholeiitic to Na-alkaline geochemical affinity associated to tectonic instability. The consequent thermal perturbations induced re-equilibration stages of the chromitite zircons, which ended with the Early Jurassic exhumation documented by the U-Pb ages of chromitite zircons of this study. Our data are in agreement with the interpretation that the Early Jurassic extensional tectonics was characterised by an important reheating event at 190 Ma, possibly due to lithospheric hyperextension. Such a scenario considers that the PP unit resided at mantle depths during Early Permian, being possibly emplaced at crustal levels only thanks to trans-lithospheric faults during the Early Jurassic. This evolution is completely different with respect to the present day interpretation of the geodynamic history of the mantle bodies in the Val Sesia area, which are believed to have been emplaced within the continental crust, as part of accretionary prisms, since the end of the Variscan orogeny or before. This evidence confirms that the northernmost part of the Ivrea-Verbano Zone underwent peculiar Paleozoic to Mesozoic geodynamic processes, thus unravelling important additional complexities to the interpretation of the geodynamic evolution of the area now related to the Southern Alps
Composite Melt–Rock Interactions in the Lowermost Continental Crust: Insights from a Dunite–Pyroxenite–Gabbronorite Association of the Mafic Complex from the Ivrea–Verbano Zone (Italian Alps)
No full textThe processes leading to the building of the continental crust through magmatic underplating are fundamentally unknown, mainly because of the rare accessibility to deep level sections of the continental crust. The Italian Alps expose the Permian Mafic Complex, an 8-km-thick gabbronorite–diorite batholith that intruded the lower continental crust during the post-Variscan transtensional tectonics. We present here a petrological and geochemical study of a concentric dunite–pyroxenite–gabbronorite association, called Monte Mazzucco sequence, enclosed at deep levels of the Mafic Complex, thereby allowing us to provide new insights into the magmatic processes driven by emplacement of mantle melts in deep crustal continental areas. The studied sequence includes a ~ 60-m-thick dunite lens, in which olivine (82 mol % forsterite) is associated with accessory Cr-spinel including blebs and lamellae made up of magnetite. The dunite lens is permeated by mm- to cm-scale thick magmatic veins, which range in composition from hornblende lherzolite to olivine hornblendite and hornblende websterite. The lens is mantled by a m-scale ring consisting of amphibole-bearing (≤1 vol %) websterite, and the websterite ring is in turn enclosed by amphibole-free gabbronorites. Both magmatic veins within the dunites and mantling websterites typically include an oxide association of Al-spinel and magnetite. Remarkably, the hornblende websterite veins and the mantling websterites are typically plagioclase-free and include clinopyroxene and amphibole with chondrite-normalized rare earth element patterns characterized by negative Eu anomaly. The mantling websterites display a subtle, gradual outward decrease of Mg# for orthopyroxene, clinopyroxene and accessory olivine, coupled with an increase of the negative Eu anomaly in clinopyroxene and amphibole. The enclosing gabbronorites are amphibole-free and have a chemically evolved signature. We propose a petrogenetic scenario including two major events of melt–dunite interaction. The first resulted from focused reactive melt infiltration and formed the magmatic veins within dunites. The hornblende lherzolite and the olivine hornblendite veins were produced by focused reactive melt migration through dunite grain boundaries, involving dissolution of olivine and recrystallization of Cr-spinel into Al-spinel and magnetite, whereas the hornblende websterite veins crystallized from melts penetrating through narrow fractures and recording earlier plagioclase fractionation. Most likely, the infiltrating melts were overall derived from an evolving H2O-rich magma emplaced below the dunite body. The second event of melt–dunite reactive interaction developed the websterite ring around dunites. We envision that the outermost domain of the dunite body was replaced by websterites in response to reaction with an invading H2O-poor melt, which had previously undergone plagioclase fractionation. The dunite replacement occurred under dynamic conditions, which promoted the reaction progress, thereby leading to total or almost total dissolution of precursor olivine, and started to form the lens shape of the Monte Mazzucco ultramafic association. The gabbronorites closely adjacent to the websterite ring represent the crystallization products of the invading melt
The petrology and geochemistry of Nyiragongo lavas of 2002, 2016, 1977 and 2017 AD, and the trace element partitioning between melilitite glass and melilite, nepheline, leucite, clinopyroxene, apatite, olivine and Fe-Ti oxides: a unique scenario
Full text linkSolar driven thermal energy storage for domestic applications in heating and cooling
No full textFBK-REET labs have developed a new solar driven cooling/heating machine based on a double adsorption/desorption cycle.
The machine is provided of thermal energy storage realized by the use of microporous material. The material is regenerated by solar thermal collectors and provides heating and cooling by adsorption cycle integrated with an evaporative system. The system may be scaled in cooling/heating capacity, changing the porous material volumes, and in cooling power, changing the air flow through the system.
A prototype has been built, provided of a cooling capacity of 25-30 kWhth and a retrofittable cooling power of 2-5 kWth . The cold temperature is between 1216°C. The COP is 0,70,9.
The system may operate on open or closed cycles, for floor plants or for direct air fan systems.
The system has been tested. Preliminary results on working conditions, system performances, cycle COP and efficiency will be provided
Novel concept for a Solar Cooler/Heater based on Adsorption cycle for domestic application
No full textSolar driven cooling machines have been employed until recent years only in niche markets due to a series of reasons: dimensions of the machines, cooling power storage, production costs, and others.
At present times there's a high request for a reliable technology developed for domestic applications at distributed level. The R&D performed at FBK-REET labs has produced a new concept of solar driven cooling/heating machine based on a double adsorption/desorption cycle acting between two small tanks. The machine, acting cyclically between desorption and adsorption, is provided of an heat storage to separate the cooling energy availability from the solar radiation. Thus the system is able to provide not only cooling power in hot periods, but even heating in colder times or for hot sanitary water production. The system may be scaled up or down in cooling capacity, acting on the porous adsorbing material volumes, and in cooling power, changing the air mass flow through the system. A prototype has been built, provided of a cooling capacity of about 25 kWhth and a cooling power of 2 kWth in the range of 1216°C. The overall COP is in the range of 0,60,7. The system is patent pending (Publication number: WO2008099262)
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