3,944 research outputs found
On Resilient Behaviors in Computational Systems and Environments
The present article introduces a reference framework for discussing
resilience of computational systems. Rather than a property that may or may not
be exhibited by a system, resilience is interpreted here as the emerging result
of a dynamic process. Said process represents the dynamic interplay between the
behaviors exercised by a system and those of the environment it is set to
operate in. As a result of this interpretation, coherent definitions of several
aspects of resilience can be derived and proposed, including elasticity, change
tolerance, and antifragility. Definitions are also provided for measures of the
risk of unresilience as well as for the optimal match of a given resilient
design with respect to the current environmental conditions. Finally, a
resilience strategy based on our model is exemplified through a simple
scenario.Comment: The final publication is available at Springer via
http://dx.doi.org/10.1007/s40860-015-0002-6 The paper considerably extends
the results of two conference papers that are available at http://ow.ly/KWfkj
and http://ow.ly/KWfgO. Text and formalism in those papers has been used or
adapted in the herewith submitted pape
Domain wall suppression in trapped mixtures of Bose-Einstein condensates
The ground state energy of a binary mixture of Bose-Einstein condensates can
be estimated for large atomic samples by making use of suitably regularized
Thomas-Fermi density profiles. By exploiting a variational method on the trial
densities the energy can be computed by explicitly taking into account the
normalization condition. This yields analytical results and provides the basis
for further improvement of the approximation. As a case study, we consider a
binary mixture of Rb atoms in two different hyperfine states in a double
well potential and discuss the energy crossing between density profiles with
different numbers of domain walls, as the number of particles and the
inter-species interaction vary.Comment: 9 page
Characterizing and measuring multipartite Entanglement
A method is proposed to characterize and quantify multipartite entanglement
in terms of the probability density function of bipartite entanglement over all
possible balanced bipartitions of an ensemble of qubits. The method is tested
on a class of random pure states.Comment: 7 pages, 5 figures. Submitted to "International Journal of Quantum
Information
High-order Discontinuous Galerkin Solutions of Internal Low-mach Number Turbulent Flowsâ
Abstract In this work we apply the high-order Discontinuous Galerkin (DG) finite element method to internal low-Mach number turbulent flows. The method here presented is designed to improve the performance of the solution in the incompressible limit using an implicit scheme for the temporal integration of the compressible Reynolds Averaged Navier Stokes (RANS) equations. The per- formance of the scheme is demonstrated by solving a well-known test-case consisting of an abrupt axisymmetric expansion using various degrees of polynomial approximation. Computations with kâÏ model are performed to assess the modelling capabilities, with high-order accurate DG discretizations of the RANS equations, in presence of non-equilibrium flow conditions
Multipartite entanglement characterization of a quantum phase transition
A probability density characterization of multipartite entanglement is tested
on the one-dimensional quantum Ising model in a transverse field. The average
and second moment of the probability distribution are numerically shown to be
good indicators of the quantum phase transition. We comment on multipartite
entanglement generation at a quantum phase transition.Comment: 10 pages, 6 figures, final versio
The new integrated aeromagnetic map of the Phlegrean Fields volcano and surrounding areas
In this paper we present and analyze the new detailed aeromagnetic data set resulting from a recent survey carried out in the Phlegrean Fields volcanic area. The survey was aimed at gaining new insight into the volcanological characteristics of the region north of Phlegrean Fields (Parete-Villa Literno area) where remarkable thickness of volcanic/sub- volcanic rocks were found in wells. Measurement of total magnetic field was performed on two different flight levels, 70 m and 400 m above the ground surface, along flight lines spaced 400 m apart. Both aeromagnetic maps show the noisy effect of linear anomalies evidently due to the presence of railway lines. To filter out these local anomalies a method based on discrete wavelet transform was used, allowing an accurate local filtering and leaving the rest of the field practically unchanged. The filtered data set was integrated with the existing Agip aeromagnetic map of the Phlegrean Fields, leading to a new aeromagnetic map of the whole Phlegrean volcanic area. The compilation of the pole reduced map and of the maps of the Analytic
Signal and of the Horizontal Derivative of the integrated data set represents a first step for the interpretation of the maps in terms of geological structures of the whole Phlegrean volcanic district
A review of the gravity and magnetic studies in the Tyrrhenian Basin and its volcanic districts
Since the Sixties, the turning point marked by the Plate Tectonics global theory has provided new ideas for the interpretation
of the complex geodynamic evolution of the Mediterranean area. The renewed interest that followed
gave a strong impulse to the geological and geophysical investigations of the Mediterranean area and, more specifically,
of the Tyrrhenian Basin. Therefore, large scale geophysical surveys and oceanographic cruises were carried
out until the end of the Eighties to fill the gap of geophysical information existing in the area until then. Afterwards,
short scale surveys were prevalent to improve the detail of the information in areas of geodynamic interest. The
gathered data sets allowed new models to be formulated, improving the knowledge of the crustal and lithospheric
structure of the Tyrrhenian Basin (and surrounding areas) and the reconstruction of its complex geodynamic evolution.
In this frame, the contribution of gravity and magnetic investigations has been unquestionable and deserves
a wide-ranging review both on large and small scale. The main features of the potential fields resulting from these
surveys will be described and the interpretative models suggested by several authors will be summarized
Robustness against parametric noise of non ideal holonomic gates
Holonomic gates for quantum computation are commonly considered to be robust
against certain kinds of parametric noise, the very motivation of this
robustness being the geometric character of the transformation achieved in the
adiabatic limit. On the other hand, the effects of decoherence are expected to
become more and more relevant when the adiabatic limit is approached. Starting
from the system described by Florio et al. [Phys. Rev. A 73, 022327 (2006)],
here we discuss the behavior of non ideal holonomic gates at finite operational
time, i.e., far before the adiabatic limit is reached. We have considered
several models of parametric noise and studied the robustness of finite time
gates. The obtained results suggest that the finite time gates present some
effects of cancellation of the perturbations introduced by the noise which
mimic the geometrical cancellation effect of standard holonomic gates.
Nevertheless, a careful analysis of the results leads to the conclusion that
these effects are related to a dynamical instead of geometrical feature.Comment: 8 pages, 8 figures, several changes made, accepted for publication on
Phys. Rev.
Aeromagnetic survey of the Somma-Vesuvius volcanic area
In this paper we present and discuss the results of a geophysical airborne survey carried out in the Somma-Vesuvius
volcanic area, Southern Italy, in 1999. The helicopter-borne survey was aimed at giving new detailed insights
into the distribution of the magnetization of the area and, therefore, into the volcanological characteristics
of the region, enhancing the knowledge given by a previous low resolution survey carried out at a regional scale
by Agip. The new survey was carried out by flying on a surface parallel to the topography of the area, along
flight lines spaced 600 m apart. The obtained total field map is dominated by a large anomaly related to the Mt.
Somma-Vesuvius complex itself and characterized by a roughly elliptical shape. High-frequency anomalies occur
in the edifice and in the area east of it, partly produced by cultural noise due to the densely inhabited area.
The compilation of the maps of the analytic signal and of the horizontal derivative of the field allowed the location
of the lateral boundaries of the magnetic sources of the area and represents a first step toward the interpretation
of the maps in terms of geological structures
Robustness of optimal working points for non-adiabatic holonomic quantum computation
Geometric phases are an interesting resource for quantum computation, also in
view of their robustness against decoherence effects. We study here the effects
of the environment on a class of one-qubit holonomic gates that have been
recently shown to be characterized by "optimal" working times. We numerically
analyze the behavior of these optimal points and focus on their robustness
against noise.Comment: 14 pages, 8 figure
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