Matematica, Fisica ed Applicazionihttp://hdl.handle.net/10556/30052019-04-23T18:28:43Z2019-04-23T18:28:43ZOn Vector-Valued Schrodinger Operators in Lp-spacesMaichine, Abdallahhttp://hdl.handle.net/10556/31312019-02-06T01:01:27Z2018-04-06T00:00:00ZOn Vector-Valued Schrodinger Operators in Lp-spaces
Maichine, Abdallah
... We construct a realization Ap of A in the spaces Lp(Rd;Cm), 1 p < 1,
that generates a contractive strongly continuous semigroup. First, by using form
methods, we obtain generation of holomorphic semigroups when the potential V
is symmetric. In the general case, we use some other techniques of functional
analysis and operator theory to get a m-dissipative realization. But in this case
the semigroup is not, in general, analytic.
We characterize the domain of the operator Ap in Lp(Rd;Cm) by using rstly
a non commutative version of the Dore-Venni theorem and then a perturbation
theorem due to Okazawa.
We discuss some properties of the semigroup such as analyticity, compactness
and positivity. We establish ultracontractivity and deduce that the semigroup is
given by an integral kernel. Here, the kernel is actually a matrix whose entries
satisfy Gaussian upper estimates.
Further estimates of the kernel entries are given for potentials with a diagonal
of polynomial growth. Suitable estimates lead to the asymptotic behavior of the
eigenvalues of the matrix Schr odinger operator when the potential is symmetric. [edited by Author]
2016 - 2017
2018-04-06T00:00:00ZEvent triggering and deep learning for particle identification in KM3NeTDe Sio, Chiarahttp://hdl.handle.net/10556/30852019-01-27T01:03:17Z2018-04-11T00:00:00ZEvent triggering and deep learning for particle identification in KM3NeT
De Sio, Chiara
Neutrino astronomy experiments like KM3NeT allow to survey the Universe leveraging
the properties of neutrinos of being electrically neutral and weakly interacting particles,
making them a suitable messenger. Observing neutrino emission in association
with electromagnetic radiation allows evaluating models for the acceleration of particles
occurring in high energy sources such as Supernovae or Active Galactic Nuclei.
This is the main goal of the ARCA project in KM3NeT. In addition, KM3NeT has
a program for lower energy neutrinos called ORCA, aimed at distinguishing between
the scenarios of “normal hierarchy” and “inverted hierarchy” for neutrino mass eigenstates.
The KM3NeT Collaboration is currently building a network of three Cherenkov telescopes
in the Mediterranean sea, in deep water off the coasts of Capopassero, Italy;
Toulon, France, and Pylos, Greece. The water overburden shields the detectors from
down-going charged particles produced by the interactions of cosmic rays in the atmosphere,
while up-going neutrinos that cross the Earth are the target of the observation.
Cosmic rays are a background to the KM3NeT signal, usually discarded by directional
information. Nevertheless, they provide a reliable reference to calibrate the detector
and work out its effective operating parameters, namely direction and energy of the
incoming particles.
Estimation of tracking capabilities is directly connected to the evaluation of the ability
of the experiment to detect astrophysical point-like sources, i.e. its discovery potential.
Being able to distinguish among the three neutrino flavours, or between neutrinos and
muons, as well as estimating the neutrino direction and energy, are the main goals
of such experiments. Trigger and reconstruction algorithms are designed to separate
the signal from background and to provide an estimation for the above mentioned
quantities, respectively... [edited by author]
2016 - 2017
2018-04-11T00:00:00ZAspetti fisico-matematici dei Materiali Auxetici con Memoria di FormaPugliese, Francescohttp://hdl.handle.net/10556/30232018-12-15T01:10:06Z2018-04-09T00:00:00ZAspetti fisico-matematici dei Materiali Auxetici con Memoria di Forma
Pugliese, Francesco
The Poisson coefficient, or Poisson’s Ratio, plays a fundamental role in the
Continuum Mechanics theory, which represents the relationship between
lateral contraction and longitudinal elongation of a material subjected to tensile
stress; in almost all materials this coefficient, commonly indicated by the letter
! , has a positive value and very close to 1/3, for common materials used in
construction, and to 1/2, for rubber materials.
In auxetic materials this ratio takes on negative values, in fact the mentioned
materials are often referred to by the acronym NPR (negative Poisson's ratio);
this entails remarkable features such as high energy absorption capacity,
fracture resistance, bending stiffness and shear strength and is due to the
particular microscopic structure of the molecules.
We will then see a modeling of these materials through the study of the
fundamental cells that compose it and with different geometries of the
microstructure (hexagonal chiral, rotation of polygons) which adequately
describe the auxetic behavior.
Moreover, from the study of the constitutive equations, we are faced with
phenomena such as phase transitions and shape memory, which highlight
further capacities of NPR materials; through the use of the fractional derivative
a particular strain-strain relationship was analyzed, following by numerical
simulations, which adequately reproduces what we call auxetic deformation. [edited by Author]
2016 - 2017
2018-04-09T00:00:00ZConflicting edges spanning trees and NP-Hard subgraph identification problemsPentangelo, Rosahttp://hdl.handle.net/10556/30202018-12-15T01:09:07Z2018-04-17T00:00:00ZConflicting edges spanning trees and NP-Hard subgraph identification problems
Pentangelo, Rosa
How often do we try to get the best result with the least effort, spend as little
time as possible to perform a task or make the most of the resources available in
the workplace? In everyday life, the word ”optimize” is therefore often present.
In particular, the optimization has as its object the study and the development of
quantitative methodologies and tools for the solution of decision problems. This is
a discipline born in the military field about 80 years ago. Over the years, it has
found application in several sectors such as logistics and production, finance and
telecommunications. Currently it has become an indispensable tool for supporting
decision-making processes. The problems faced are typically those in which decisions have to be made on the use of resources available in limited quantities in order
to respect an assigned set of constraints, maximizing, for example, the benefit obtainable from the use of the resources themselves... [edited by Author]
2016 - 2017
2018-04-17T00:00:00Z