1,667 research outputs found
On the Telegraph Process Driven by Geometric Counting Process with Poisson-Based Resetting
We investigate the effects of the resetting mechanism to the origin for a random motion on the real line characterized by two alternating velocities v1 and v2 . We assume that the sequences of random times concerning the motions along each velocity follow two independent geometric counting processes of intensity λ , and that the resetting times are Poissonian with rate ξ> 0 . Under these assumptions we obtain the probability laws of the modified telegraph process describing the position and the velocity of the running particle. Our approach is based on the Markov property of the resetting times and on the knowledge of the distribution of the intertimes between consecutive velocity changes. We obtain also the asymptotic distribution of the particle position when (i) λ tends to infinity, and (ii) the time goes to infinity. In the latter case the asymptotic distribution arises properly as an effect of the resetting mechanism. A quite different behavior is observed in the two cases when v2< 0 < v1 and 0 < v2< v1 . Furthermore, we focus on the determination of the moment-generating function and on the main moments of the process describing the particle position under reset. Finally, we analyse the mean-square distance between the process subject to resets and the same process in absence of resets. Quite surprisingly, the lowest mean-square distance can be found for ξ= 0 , for a positive ξ , or for ξ→ + ∞ depending on the choice of the other parameters
Flood hazard of the Somma-Vesuvius region based on historical (19-20th century) and geomorphological data
This paper presents a preliminary susceptibility map of the flood hazard
for the Somma-Vesuvius volcanic district, worked out by means of multidisciplinary
historical, geological, geomorphological and rainfall data
processing. It is well known that the Somma-Vesuvius volcano, due to its
explosive volcanism and the dense urbanization of the surrounding area,
with a population exceeding 650,000 is one of the most dangerous active
volcanoes of the world. Although this area has been extensively studied
from the volcanological point of view with regards to its volcanic hazard,
there are currently not many detailed studies about its flood hazard factors,
despite the fact that, in the last century, many intense rainfall events
in this area have produced several floods that invaded the surrounding
plains affecting towns and roads, and causing much damages and loss of
lives. Accordingly, in this paper high-resolution DEM (5×5 m pixel) and
detailed geomorphological maps of the whole area have been analyzed
and processed in GIS environment, carrying out a comparative study of
the present-day morphology and the morphology of the 1900’s volcanic edifice,
including changes of infrastructures and buildings throughout the
last century. These results, together with historical chronicles data and
the rainfall accurate data for all flood events, have been processed in this
paper for highlighting the drainage basins areas of Somma-Vesuvius
where the flood phenomena could be more probable in the future, working
out a preliminary zoning map, also suggesting in which sectors interventions
useful for mitigation of flood risk should be implemented
Directionality preservation of nuclear recoils in an emulsion detector for directional dark matter search
Nuclear emulsion is a well-known detector type proposed also for the
directional detection of dark matter. In this paper, we study one of the most
important properties of direction-sensitive detectors: the preservation by
nuclear recoils of the direction of impinging dark matter particles. For
nuclear emulsion detectors, it is the first detailed study where a realistic
nuclear recoil energy distribution with all possible recoil atom types is
exploited. Moreover, for the first time we study the granularity effect on the
emulsion detector directional performance. As well as we compare nuclear
emulsion with other directional detectors: in terms of direction preservation
nuclear emulsion outperforms the other detectors for WIMP masses above 100
GeV/c.Comment: Prepared for submission to JCA
Flood susceptibility assessment in a highly urbanized alluvial fan: the case study of Sala Consilina (southern Italy)
Abstract. This paper deals with the risk assessment to alluvial fan flooding at the piedmont zone of carbonate massifs of the southern Apennines chain (southern Italy). These areas are prime spots for urban development and are generally considered to be safer than the valley floors. As a result, villages and towns have been built on alluvial fans which, during intense storms, may be affected by flooding and/or debris flow processes. The study area is located at the foothills of the Maddalena mountains, an elongated NW-SE trending ridge which bounds to the east the wide intermontane basin of Vallo di Diano. The area comprises a wide detrital talus (bajada) made up by coalescent alluvial fans, ranging in age from the Middle Pleistocene to the Holocene. Historical analysis was carried out to ascertain the state of activity of the fans and to identify and map the zones most hit by past flooding. According to the information gathered, the Sala Consilina fans would appear prone to debris flows; in the past these processes have produced extensive damage and loss of life in the urban area. The watershed basins feeding the fans have very low response times and may produce debris flow events with high magnitudes. Taking into account the historical damage, the fan surface morphology, and the present urban development (street orientation and hydraulic network), the piedmont area was zoned and various susceptibility classes were detected. These results may represent a useful tool for studies aiming at territorial hazard mapping and civil protection interventions
High-resolution tracking in a GEM-Emulsion detector
SHiP (Search for Hidden Particles) is a beam dump experiment proposed at the
CERN SPS aiming at the observation of long lived particles very weakly coupled
with ordinary matter mostly produced in the decay of charmed hadrons. The beam
dump facility of SHiP is also a copious factory of neutrinos of all three kinds
and therefore a dedicated neutrino detector is foreseen in the SHiP apparatus.
The neutrino detector exploits the Emulsion Cloud Chamber technique with a
modular structure, alternating walls of target units and planes of electronic
detectors providing the time stamp to the event. GEM detectors are one of the
possible choices for this task. This paper reports the results of the first
exposure to a muon beam at CERN of a new hybrid chamber, obtained by coupling a
GEM chamber and an emulsion detector. Thanks to the micrometric accuracy of the
emulsion detector, the position resolution of the GEM chamber as a function of
the particle inclination was evaluated in two configurations, with and without
the magnetic fiel
A double-ended queue with catastrophes and repairs, and a jump-diffusion approximation
Consider a system performing a continuous-time random walk on the integers,
subject to catastrophes occurring at constant rate, and followed by
exponentially-distributed repair times. After any repair the system starts anew
from state zero. We study both the transient and steady-state probability laws
of the stochastic process that describes the state of the system. We then
derive a heavy-traffic approximation to the model that yields a jump-diffusion
process. The latter is equivalent to a Wiener process subject to randomly
occurring jumps, whose probability law is obtained. The goodness of the
approximation is finally discussed.Comment: 18 pages, 5 figures, paper accepted by "Methodology and Computing in
Applied Probability", the final publication is available at
http://www.springerlink.co
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