1,181 research outputs found
Development of a Pilot Borehole Storage System of Solar Thermal Energy: Modeling, Design, and Installation
Borehole thermal energy storage systems represent a potential solution to increase the energy efficiency of renewable energy plants, but they generally have to comply with strict regulatory frameworks, mainly due to the deliberate modification of the subsoilâs natural state. This paper presents the design, testing, and monitoring phases carried out to set up a borehole thermal energy storage (BTES) system able to exploit the excess solar heat from photovoltaic thermal (PVT) collectors. The case study is the refurbishment of a pig nursery barn, hosting up to 2500 weaners, in Northern Italy. This study aims to define a BTES suitable to develop a heating system based on renewable energy, ensuring environmental protection and long-term sustainability. The retrofitting intervention includes the installation of a dual-source heat pump (DSHP), in order to recover the solar heat stored in summer during winter. Specific constraints by the Environmental Authority were as follows: maximum storage temperature of 35 °C, authorization to intercept the shallowest aquifer at a maximum depth of 30 m, obligation of BHE grouting, and the definition of a strategy for continuous measuring and monitoring of the groundwaterâs thermophysical properties. The results were used as inputs to optimize the design and installation of the integrated system with PVT, BTES, and DSHP
VLBA images of High Frequency Peakers
We propose a morphological classification based on the parsec scale structure
of fifty-one High Frequency Peakers (HFPs) from the ``bright'' HFP sample. VLBA
images at two adjacent frequencies (chosen among 8.4, 15.3, 22.2 and 43.2 GHz)
have been used to investigate the morphological properties of the HFPs in the
optically thin part of their spectrum. We confirm that there is quite a clear
distinction between the pc-scale radio structure of galaxies and quasars: the
78% of the galaxies show a ``Double/Triple'' morphology, typical of Compact
Symmetric Objects (CSOs), while the 87% of the quasars are characterised by
Core-Jet or unresolved structure. This suggests that most HFP candidates
identified with quasars are likely blazar objects in which a flaring
self-absorbed component at the jet base was outshining the remainder of the
source at the time of the selection based on the spectral shape. Among the
sources classified as CSOs or candidates it is possible to find extremely young
radio sources with ages of about 100 years or even less.Comment: 21 pages, 8 figures; accepted for pubblication in A&A. Paper version
with full resolution images is available at
http://www.ira.inaf.it/~ddallaca/orienti.p
ISPAD Clinical Practice Consensus Guidelines 2022: The delivery of ambulatory diabetes care to children and adolescents with diabetes
info:eu-repo/semantics/publishedVersio
Geoarchaeological Evidence of Middle-Age Tsunamis at Stromboli and Consequences for the Tsunami Hazard in the Southern Tyrrhenian Sea
Large-scale landslides at volcanic islands are one of the most dangerous geological phenomena, able to generate tsunamis whose effects can propagate far from the source. However, related deposits are scarcely preserved on-land in the geologic records, and are often difficult to be interpreted. Here we show the discovery of three unprecedented well-preserved tsunami deposits related to repeated flank collapses of the volcanic island of Stromboli (Southern Italy) occurred during the Late Middle Ages. Based on carbon datings, on stratigraphic, volcanological and archaeological evidence, we link the oldest, highest-magnitude investigated tsunami to the following rapid abandonment of the island which was inhabited at that time, contrary than previously thought. The destructive power of this event is also possibly related to a huge marine storm that devastated the ports of Naples in 1343 (200\u2009km north of Stromboli) described by the famous writer Petrarch. The portrayed devastation can be potentially attributed to the arrival of multiple tsunami waves generated by a major landslide in Stromboli island, confirming the hypothetical hazard of these phenomena at a regional scale
RATAN-600 7.6-cm Deep Sky Strip Surveys at the Declination of the SS433 Source During the 1980-1999 Period. Data Reduction and the Catalog of Radio Sources in the Right-Ascension Interval 7h < R.A. < 17h
We use two independent methods to reduce the data of the surveys made with
RATAN-600 radio telescope at 7.6 cm in 1988-1999 at the declination of the
SS433 source. We also reprocess the data of the "Cold" survey (1980-1981). The
resulting RCR (RATAN COLD REFINED) catalog contains the right ascensions and
fluxes of objects identified with those of the NVSS catalog in the
right-ascension interval 7h < R.A. < 17h. We obtain the spectra of the radio
sources and determine their spectral indices at 3.94 and 0.5 GHz. The spectra
are based on the data from all known catalogs available from the CATS, Vizier,
and NED databases, and the flux estimates inferred from the maps of the VLSS
and GB6 surveys. For 245 of the 550 objects of the RCR catalog the fluxes are
known at two frequencies only: 3.94 GHz (RCR) and 1.4 GHz (NVSS). These are
mostly sources with fluxes smaller than 30 mJy. About 65% of these sources have
flat or inverse spectra (alpha > -0.5). We analyze the reliability of the
results obtained for the entire list of objects and construct the histograms of
the spectral indices and fluxes of the sources. Our main conclusion is that all
10-15 mJy objects found in the considered right-ascension interval were already
included in the decimeter-wave catalogs.Comment: 26 pages, 18 figure
The tsunamigenic potential of landslide-generated tsunamis on the Vavilov seamount
The investigation of submarine volcanoes and the tsunamigenic potential of possible movements on their flanks is arduous. In most cases, the lack of specific information about the eruptionsâ history and their consequences does not allow a comprehensive analysis in terms of hazard. Nevertheless, useful clues on the possible occurrence of mass movements on seamounts can be obtained from a series of research fields. These account for morphological studies, observations of hydrothermal activity, collection of geophysical data (for example, detailed DEM, seismic profiles, magnetic data), etc. In this context, this study presents new bathymetric data of the Vavilov submarine volcano (Tyrrhenian Sea, Italy) and a detailed morphological analysis of the structure. The latter allows the identification of zones potentially prone to mass movements and the development of numerical scenarios to investigate the tsunami potential associated to these movements on the Vavilov flanks. Results prove that the waves generated by the mass displacements in the proposed scenarios (involving sliding volumes between 0.32 km3 and 1.7 km3) reach maximum values in the order of centimetres, not considering dispersive effects. Eventually, a scenario involving the partial collapse of the west flank of the Vavilov Seamount is simulated, although the occurrence of such an event in the past is still debated due to the uncertainties related to the origin and development of the volcano dome. In this scenario, water elevation as high as 10 m are found in large portions of the Tyrrhenian coasts: waves are large enough to emplace sizeable tsunami deposits onshore, that could have been preserved until today in some specific stretches of the coast and could be detected by a finalised geological search. This study belongs to a series of works devoted to the submarine structures of the Tyrrhenian Sea aiming to disclose the tsunamigenic potential of submarine mass movements on their flanks
High Frequency Peakers: young radio sources or flaring blazars?
We present new, simultaneous, multifrequency observations of 45 out of the 55
candidate High Frequency Peakers (HFP) selected by Dallacasa et al. (2000),
carried out 3 to 4 years after a first set of observations. Our sub-sample
consists of 10 galaxies, 28 stellar objects (``quasars'') and 7 unidentified
sources. Both sets of observations are sensitive enough to allow the detection
of variability at the 10% level or lower. While galaxies do not show
significant variability, most quasars do. Seven of them no longer show the
convex spectrum which is the defining property of Gigahertz Peaked Spectrum
(GPS)/HFP sources and are interpreted as blazars caught by Dallacasa et al.
(2000) during a flare, when a highly self-absorbed component dominated the
emission. In general, the variability properties (amplitude, timescales,
correlation between peak luminosity and peak frequency of the flaring
component) of the quasar sub-sample resemble those of blazars. We thus conclude
that most HFP candidates identified with quasars may well be flaring blazars.Comment: 20 pages, 18 figures, accepted for publication in Astronomy &
Astrophysic
The B3-VLA CSS sample. II: VLBA images at 18 cm
VLBA observations at 18 cm are presented for 28 Compact Steep-spectrum radio
Sources (CSSs) from the B3-VLA CSS sample. These sources were unresolved in
previous VLA observations at high frequencies or their brightness distribution
was dominated by an unresolved steep spectrum component. More than half of them
also showed a low frequency turnover in their radio spectrum. The VLBA images
display in most cases a compact symmetric structure. Only in a minority of
cases complex morphologies are present.Comment: 11 pages, many low resolution figures, A&A accepted. A higher quality
g-zipped postscript file can be found at
http://www.ira.cnr.it/~ddallaca/h3442.ps.g
Further investigations of underground resistivity structures in coastal areas using grounded-source airborne electromagnetics
- âŠ