6,421 research outputs found
Exotic Searches
The experimental information on the search for non mesons as
glueballs, hybrids and multiquark states is reviewed. Candidate states which
are particularly amenable to detailed study by accumulating large samples of
, , decays at a -charm factory are discussed.Comment: 25 pages, LaTex, 22 Figures (available from the authors on request),
BARI-TH/94-17
Evidences of a contractional pattern along the northern rim of the Hyblean Plateau (Sicily, Italy) from GPS data
In this paper we present the main results inferred from GPS data collected between 1998.00 and 2009.78 along the northern rim of the Hyblean Plateau from 9 continuous and 23 survey-mode sites. From a geological point of view, this area is of great interest because 1) it represents an important piece of the collision front between Nubia and Eurasia 2) it is very close to the biggest European volcano Mount Etna and 3) it has been hit by strong earthquakes in the past (1169 and 1693) that struggled the cities of Catania, Siracusa and Ragusa provoking tens of thousands of casualties. We have found that the ground deformation pattern clearly defines an area of prevailing contraction along the northern rim of the Hyblean Plateau with a maximum negative strain-rate of about 0.14Âľstrain/yr in agreement with both geological and Interferometric Synthetic Aperture Radar (InSAR) data. In addition, a transition to extensional regime is acting toward the central sector of the plateau. The velocity field referred to the Eurasian frame indicates that a large part of the plateau is dominated by a 5.4mm/yr northward motion
Kf evaluation in GFRP composites by thermography
Since the presence of a notch in a mechanical component causes a reduction in the fatigue strength, it is important to know the kf value for a given notch geometry and material. This parameter is fundamental in the fatigue design of aeronautical components that are mainly made of composites. kf is available in the literature for numerous types of notch but only for traditional materials such as metals. This paper presents a new practice, based on thermographic data, for the determination of the fatigue notch coefficient kf in composite notched specimens. The innovative aspect of this study is therefore to propose the application on composite materials of a new thermographic procedure to determine kf for several notch geometries: circular, U and V soft and severe notches. It was calculated, for each type of notch, as the ratio between the fatigue limits obtained on the cold and hot zone corresponding to the smooth and notched specimen, respectively. Consequently, this research activity provides, for the first time, a little database of kf for two particular typologies of composite materials showing a fast way to collect further values for different laminates and notch geometries
Ground deformation at Mt. Etna: a joint interpretation of GPS and InSAR data from 1993 to 2000
Combined GPS measurements and radar interferometry (InSAR) have been applied at Mt. Etna to study the ground deformation affecting the volcano both over the long- (1993-2000) and short-term (1997-1998 and 1998-2000). The aim was to better understand the dynamics of the volcano during the magma-recharging phase following the 1991-93 eruption.
Since 1993, InSAR and GPS data indicate that Mt. Etna has undergone an inflation. A deep intrusion was detected by InSAR, on the western flank of the volcano, between March and May 1997. In the following months, this intrusion rose up leading to a seismic swarm occurring in January 1998 in the western sector. This now shallow intrusion is confirmed by GPS data. From 1998 to 2000, a general deflation affecting the upper part of the volcano was detected.
Over the whole study period, a continuous eastward to south-eastward motion of the eastern sector of the volcano was also evidenced. The analytical inversions of GPS data inferred a plane dipping about 12°ESE, located beneath the eastern flank of the volcano at a depth of 1.4 km b.s.l.. The movement along this plane is able to reproduce the observed south-eastward motion of a sector bounded northward by the Pernicana fault, westward by the North-East Rift and the South Rift, and southward by the Mascalucia-Tremestieri-Trecastagni fault system. InSAR data have validated this model
Iterated uniform finite-state transducers
A deterministic iterated uniform finite-state transducer (for short, iufst) operates the same length-preserving transduction on several left-to-right sweeps. The first sweep occurs on the input string, while any other sweep processes the output of the previous one. We focus on constant sweep bounded iufsts. We study their descriptional power vs. deterministic finite automata, and the state cost of implementing language operations. Then, we focus on non-constant sweep bounded iufsts, showing a nonregular language hierarchy depending on sweep complexity
Application of differential SAR interferometry for studying eruptive event of 22July 1998 at Mt.Etna
One of the main objectives of the project
âDevelopment and application of remote sensing
methods for the monitoring of active Italian
volcanoesâ is directed to an operational use of
differential interferometry as a tool for volcano
monitoring. A first step to achieve this goal is to
test commercial software in order to evaluate
the most suitable for the project purposes. For
testing software, SAR images collected by
ERS2 from May 98 to August 98, before and
after the strong eruptive event occurred on 22
July 98 at Voragine crater of Etna, have been
selected. The explosive event was classified
sub-plinian producing a 12 km high eruptive
column and lapilli fell on land as far as 70 km
south-eastward along the dispersal axis. Pre,
post and across event image pairs have been
processed. In particular the pair 13 May 98-22
July 98, 22 July 98-26 August 98, 13 May 98-26
August 98 are used for testing respectively pre,
post and across event. In first analysis, the
fringes in the differential products show a positive
elevation trend in the summit area of the
volcano. In particular, an increased of about 1,5
fringes in the period pre-event, and a decrement
of 1 fringe in the period post-event is observed.
This result is agreement whit field of deformation
expected in such kind of event, confirming
that the interferometric processing tool used id
suitable for the purpose of the project
Ground deformation modeling of flank dynamics prior to the 2002 eruption of Mt. Etna
On 22 September 2002, 1 month before the
beginning of the flank eruption on the NE Rift, an M-3.7
earthquake struck the northeastern part of Mt. Etna, on the
westernmost part of the Pernicana fault. In order to
investigate the ground deformation pattern associated with
this event, a multi-disciplinary approach is presented here.
Just after the earthquake, specific GPS surveys were carried
out on two small sub-networks, aimed at monitoring the
eastern part of the Pernicana fault, and some baselines
belonging to the northeastern EDM monitoring network of
Mt. Etna were measured. The leveling route on the
northeastern flank of the volcano was also surveyed.
Furthermore, an investigation using SAR interferometry
was performed and also the continuous tilt data recorded at
a high precision sensor close to the epicenter were analyzed
to constrain the coseismic deformation. The results of the
geodetic surveys show a ground deformation pattern that
affects the entire northeastern flank of the volcano, clearly
shaped by the Pernicana fault, but too strong and wide to be
related only to an M-3.7 earthquake. Leveling and DInSAR
data highlight a local strong subsidence, up to 7 cm, close
to the Pernicana fault. Significant displacements, up to
2 cm, were also detected on the upper part of the NE Rift
and in the summit craters area, while the displacements decrease at lower altitude, suggesting that the dislocation
did not continue further eastward. Three-dimensional GPS
data inversions have been attempted in order to model the
ground deformation source and its relationship with the
volcano plumbing system. The model has also been
constrained by vertical displacements measured by the
leveling survey and by the deformation map obtained by
SAR interferometry
Multidisciplinary study of the Tindari Fault (Sicily, Italy) separating ongoing contractional and extensional compartments along the active AfricaâEurasia convergent boundary
The AfricaâEurasia convergence in Sicily and southern Calabria is currently expressed by two different tectonic
and geodynamic domains: thewestern region, governed by a roughlyNâS compression generated by a continental
collision; the eastern one, controlled by a NWâSE extension related to the south-east-directed expansion of
the CalabroâPeloritan Arc. The different deformation pattern of these two domains is accommodated by a
right-lateral shear zone (AeolianâTindariâLetojanni fault system) which, from the Ionian Sea, north of Mt.
Etna, extends across the Peloritani chain to the Aeolian Islands.
In this work, we study the evidence of active tectonics characterizing this shear zone, through the analysis of
seismic and geodetic data acquired by the INGV networks in the last 15 years. The study is completed by
structural and morphological surveys carried out between Capo Tindari and the watershed of the chain.
The results allowed defining a clear structural picture depicting the tectonic interferences between the two
different geodynamic domains. The results indicate that, besides the regional ~N130°E horizontal extensional
stress field, another one, NEâSW-oriented, is active in the investigated area. Both tension axes are mutually
independent and have been active up to the present at different times. The coexistence of these different
active horizontal extensions is the result of complex interactions between several induced stresses: 1) the
regional extension (NWâSE) related to the slab rollback and back-arc extension; 2) the strong uplift of the
chain; 3) the accommodation between compressional and extensional tectonic regimes along the Aeolianâ
TindariâLetojanni faults, through a SSEâNNW right-lateral transtensional displacement. In these conditions,
the greater and recurring uplift activity is not able to induce a radial extensional dynamics, but, under the
âdirectingâ action of the shear system, it can only act on the regional extension (NWâSE) and produce the
second system of extension (NEâSW)
Etn@ref: a geodetic reference frame for Mt. Etna GPS networks
In volcanology, one of the most important instruments for scientific community interested in modelling the physical processes related to magma movements in the shallow crust is geodetic data. Since the end of the 1980s, GPS surveys and Continuous GPS stations (CGPS) have greatly improved the possibility to measure such movements with high time and space resolution. However, physical modelling requires that any external influence on the data, not directly related to the investigated quantity, must be filtered. One major tricky factor in determining a deformation field using GPS displacement vectors and velocities is the correct choice of a stable reference frame. In this work, using more than a decade of GPS measurements, we defined a local reference frame in order to refer the Mt. Etna ground deformation pattern to a rigid block. In particular, we estimated the Euler pole for the rigid block by minimizing, with a weighted least squares inversion, the adjustments to two horizontal components of GPS velocity at 13 âfiducialâ sites located within 350 km around Mt. Etna. The inversion inferred an Euler pole located at 38.450° N and -107.702° E and a rotation rate of 0.263 deg/Myr
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