1,243 research outputs found
Seismic vulnerability assessment on a territorial scale based on a Bayesian approach
Italian historical centres are mostly characterized by aggregate buildings. As defined by
the Italian codes (Norme Tecniche per le Costruzioni 2008 and Circolare n. 617), the analysis of the most
representative local mechanisms of collapse must be performed in order to assess their vulnerability. In
this article, the out-of-plane local mechanisms of collapse analysis is implemented by applying a new
method of analysis based on a probabilistic approach. Usually information which are necessary for the
implementation of the local mechanisms analyses are affected by uncertainty or are missing, therefore
in lots of cases it is only possible to hypothesize them on the basis of the other buildings information
collected during the on-site survey. In this context, the implementation of a Bayesian approach allows to
deduce buildings lacking information (i.e. wall thickness and interstorey height) starting from certain collected
data (i.e. facades height). The historical centre of Timisoara (Romania) is selected as the case study
for the implementation of this new method of analysis, given the extension of the on-site survey already
carried out in the area (information about more than 200 structural units have been collected) and the
seismic vulnerability assessment on an urban scale already performed by applying a traditional method.
Results obtained by adopting the two approaches are then compared and a validation and a calibration
of the new one is carried out
The application of a Bayesian approach to assess the seismic vulnerability of historical centers
The seismic vulnerability of historical centers at a territorial scale cannot be assessed performing
detailed analysis which are usually adopted at the single building scale. In fact, a traditional complete survey
would be extremely time-consuming and not sustainable for this purpose.
The approach described in this paper is based on the idea that it is possible to infer quantities which cannot be directly
detected from buildings outside inspection starting from parameters that can be measured. In order to
achieve this purpose, a Bayesian approach is applied, updating initial hypotheses when new data become available.
In this context, the procedure herein proposed aims at applying a probabilistic approach instead of a deterministic
one to define facades inter-storey height starting from buildings height knowledge. In order to validate the method,
for out of plane local mechanisms of collapse (walls overturning), horizontal loads multiplier \uf0610 values are calculated
and compared to results obtained by using data collected on-site
Quark nuggets search using 2350 Kg gravitational waves aluminum bar detectors
The gravitational wave resonant detectors can be used as detectors of quark
nuggets, like nuclearites (nuclear matter with a strange quark). This search
has been carried out using data from two 2350 Kg, 2 K cooled, aluminum bar
detectors: NAUTILUS, located in Frascati (Italy), and EXPLORER, that was
located in CERN Geneva (CH). Both antennas are equipped with cosmic ray shower
detectors: signals in the bar due to showers are continuously detected and used
to characterize the antenna performances. The bar excitation mechanism is based
on the so called thermo-acoustic effect, studied on dedicated experiments that
use particle beams. This mechanism predicts that vibrations of bars are induced
by the heat deposited in the bar from the particle. The geometrical acceptance
of the bar detectors is 19.5 sr, that is smaller than that of other
detectors used for similar searches. However, the detection mechanism is
completely different and is more straightforward than in other detectors. We
will show the results of ten years of data from NAUTILUS (2003-2012) and 7
years from EXPLORER (2003-2009). The experimental limits we obtain are of
interest because, for nuclearites of mass less than grams, we find a
flux smaller than that one predicted considering nuclearites as dark matter
candidates.Comment: presented to the 33rd International Cosmic Ray Conference Rio de
Janeiro 201
All-sky upper limit for gravitational radiation from spinning neutron stars
We present results of the all-sky search for gravitational-wave signals from
spinning neutron stars in the data of the EXPLORER resonant bar detector. Our
data analysis technique was based on the maximum likelihood detection method.
We briefly describe the theoretical methods that we used in our search. The
main result of our analysis is an upper limit of for
the dimensionless amplitude of the continuous gravitational-wave signals coming
from any direction in the sky and in the narrow frequency band from 921.00 Hz
to 921.76 Hz.Comment: 12 pages, 4 figures, submitted to Proceedings of 7th Gravitational
Wave Data Analysis Workshop, December 17-19, 2002, Kyoto, Japa
Search for Periodic Gravitational Wave Sources with the Explorer Detector
We have developped a procedure for the search of periodic signals in the data
of gravitational wave detectors. We report here the analysis of one year of
data from the resonant detector Explorer, searching for pulsars located in the
Galactic Center (GC). No signals with amplitude greater than , in the range 921.32-921.38 Hz, were observed using data
collected over a time period of 95.7 days, for a source located at
hours and degrees. Our
procedure can be extended for any assumed position in the sky and for a more
general all-sky search, even with a frequency correction at the source due to
the spin-down and Doppler effects.Comment: One zipped file (Latex+eps figures). 33 pages, 14 figures. This and
related material also at http://grwav3.roma1.infn.it
Effect of cosmic rays on the resonant gravitational wave detector NAUTILUS at temperature T=1.5 K
The interaction between cosmic rays and the gravitational wave bar detector
NAUTILUS is experimentally studied with the aluminum bar at temperature of
T=1.5 K. The results are compared with those obtained in the previous runs when
the bar was at T=0.14 K. The results of the run at T = 1.5 K are in agreement
with the thermo-acoustic model; no large signals at unexpected rate are
noticed, unlike the data taken in the run at T = 0.14 K. The observations
suggest a larger efficiency in the mechanism of conversion of the particle
energy into vibrational mode energy when the aluminum bar is in the
superconductive status.Comment: 7 pages, 3 figures, 2 tables. Accepted by Physics Letters
Experimental evaluation of a solid oxide fuel cell system exposed to inclinations and accelerations by ship motions
Solid Oxide Fuel Cell (SOFC) systems have the potential to reduce emissions from seagoing vessels. However, it is unknown whether ship motions influence the system's operation. In this research, a 1.5 kW SOFC module is operated on an inclination platform that emulates ship motions, to evaluate the influence of static and dynamic inclinations on the system's safety, operation, and lifetime. The test campaign consists of a static inclination test, a dynamic test, a degradation test, and a high acceleration test. There were no interruptions in the power supply during the different tests, and no detectable gas leakages or safety hazards. Although the SOFC does not fail in any test condition, dynamic inclinations result in forced oscillations in the fuel regulation, which propagate through the system by different feedback loops in the control architecture, leading to significant deviations in the operational parameters of the system. Additionally, for motion periods from 16 to 26 s, reoccurring exceedance of the fuel utilisation results in a gradual reduction of the power supply. Several enhancements are recommended to improve the design of SOFCs and marine fuel cell regulations to ensure their safe operation on ships.</p
Analysis of 3 years of data from the gravitational wave detectors EXPLORER and NAUTILUS
We performed a search for short gravitational wave bursts using about 3 years
of data of the resonant bar detectors Nautilus and Explorer. Two types of
analysis were performed: a search for coincidences with a low background of
accidentals (0.1 over the entire period), and the calculation of upper limits
on the rate of gravitational wave bursts. Here we give a detailed account of
the methodology and we report the results: a null search for coincident events
and an upper limit that improves over all previous limits from resonant
antennas, and is competitive, in the range h_rss ~1E-19, with limits from
interferometric detectors. Some new methodological features are introduced that
have proven successful in the upper limits evaluation.Comment: 12 pages, 12 figure
Study of the coincidences between the gravitational wave detectors EXPLORER and NAUTILUS in 2001
We report the result from a search for bursts of gravitational waves using
data collected by the cryogenic resonant detectors EXPLORER and NAUTILUS during
the year 2001, for a total measuring time of 90 days. With these data we
repeated the coincidence search performed on the 1998 data (which showed a
small coincidence excess) applying data analysis algorithms based on known
physical characteristics of the detectors. With the 2001 data a new interesting
coincidence excess is found when the detectors are favorably oriented with
respect to the Galactic Disk
Remote ischaemic preconditioning in coronary artery bypass surgery: a meta-analysis
Aim Randomised trials exploring remote ischaemic preconditioning (RIPC) in patients undergoing coronary artery bypass graft (CABG) surgery have yielded conflicting data regarding potential cardiovascular and renal protection, and are individually flawed by small sample size.
Methods Three investigators independently searched the MEDLINE, EMBASE and Cochrane databases to identify randomised trials testing RIPC in patients undergoing CABG.
Results Nine studies with 704 patients were included. Standardised mean difference of troponin I and T release showed a significant decrease ( 120.36 (95% CI 120.62 to 120.09)). This difference held true after excluding the trials with cross-clamp fibrillation, the study with off-pump CABG and studies using a flurane as anaesthetic agent ( 120.41 (95% CI 120.69 to 120.12), 120.38 (95% CI 120.70 to 120.07) and 120.37 (95% CI 120.63 to 120.12), respectively). A similar trend was also obtained for patients with multivessel disease ( 120.41 (95% CI 120.73 to 120.08)). The trials evaluating postoperative creatinine reported a non-significant reduction (0.02 (95% CI 120.09 to 0.13)). Moreover, the length of in-hospital stay was not influenced by the kind of treatment (weighted mean difference 0.27 (95% CI 120.24 to 0.79)).
Conclusion RIPC reduced the release of troponin in patients undergoing CABG. Larger randomised trials are needed to clarify the presence of a causal relationship between RIPC-induced troponin release and clinical adverse events
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