3,723 research outputs found
Continuous RSB mean-field solution of the Potts glass
We investigate the p-state mean-field model of the
Potts glass () below the continuous phase transition to a
glassy phase. We find that apart from a solution with a first hierarchical
level of replica-symmetry breaking (1RSB), locally stable close to the
transition point, there is a continuous full replica-symmetry breaking (FRSB)
solution. The latter is marginally stable and has a higher free energy than the
former. We argue that the true equilibrium is reached only by FRSB, being
globally thermodynamically homogeneous, whereas 1RSB is only locally
homogeneous.Comment: REVTeX4.1, 4 pages, 1 figur
Equivalence of switching linear systems by bisimulation
A general notion of hybrid bisimulation is proposed for the class of switching linear systems. Connections between the notions of bisimulation-based equivalence, state-space equivalence, algebraic and inputâoutput equivalence are investigated. An algebraic characterization of hybrid bisimulation and an algorithmic procedure converging in a finite number of steps to the maximal hybrid bisimulation are derived. Hybrid state space reduction is performed by hybrid bisimulation between the hybrid system and itself. By specializing the results obtained on bisimulation, also characterizations of simulation and abstraction are derived. Connections between observability, bisimulation-based reduction and simulation-based abstraction are studied.\ud
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A novel computational method to identify/analyze hysteresis loops of hard magnetic materials
In this study, a novel computational method capable of reproducing hysteresis loops of hard magnetic materials is proposed. It is conceptually based on the classical Preisach model but has a completely different approach in the modeling of the hysteron effect. Indeed, the change in magnetization caused by a single hysteron is compared here to the change in velocity of two disk-shaped solids elastically colliding with each other rather than the effect of ideal geometrical entities giving rise to so-called Barkhausen jumps. This allowed us to obtain a simple differential formulation for the global magnetization equation with a significant improvement in terms of computational performance. A sensitivity analysis on the parameters of the proposed method has indeed shown the capability to model a large class of hysteresis loops. Moreover, the proposed method permits modeling of the temperature effect on magnetization of neodymium magnets, which is a key point for the design of electrical machines. Therefore, application of the proposed method to the hysteresis loop of a real NdFeB magnet has been proven to be very accurate and efficient for a large temperature range
Treatment of Horizontal Canal Benign Paroxysmal Positional Vertigo: A New Rehabilitation Technique
The aim of this
study was to evaluate the effectiveness of a new
technical variant applied to the Gufoni's
manoeuvre, in the treatment of horizontal canal
benign paroxysmal positional vertigo (HSC-BPPV).
87 patients with BPPV of HSC (55 women and 32
men), aged between 21 and 80 years, were
randomized either to modified Gufoni's
manoeuvre or to the Gufoni's manoeuvre.
93% of patients treated with modified
Gufoni's manoeuvre was cured after the first
treatment session, of which only 2% had a
conversion into PSC-BPPV, while the Gufoni's
manoeuvre led to a symptoms resolution in
88% of cases, of which 16% had a
conversion into PSC-BPPV. Therefore, the
modified Gufoni's manoeuvre shows the same
effectiveness in the resolution of symptoms of
Gufoni's manoeuvre, but it appears more
effective than the latter to reduce the
percentage of conversion of the HSC-BPPV into PSC-BPPV (Ï2 = 6.13, P = 0.047)
Some non perturbative calculations on spin glasses
Models of spin glasses are studied with a phase transition discontinuous in
the Parisi order parameter. It is assumed that the leading order corrections to
the thermodynamic limit of the high temperature free energy are due to the
existence of a metastable saddle point in the replica formalism. An ansatz is
made on the form of the metastable point and its contribution to the free
energy is calculated. The Random Energy Model is considered along with the
p-spin and the p-state Potts Models in their p < infinity expansion.Comment: 12 pages, LaTe
The Glassy Potts Model
We introduce a Potts model with quenched, frustrated disorder, that enjoys of
a gauge symmetry that forbids spontaneous magnetization, and allows the glassy
phase to extend from down to T=0. We study numerical the 4 dimensional
model with states. We show the existence of a glassy phase, and we
characterize it by studying the probability distributions of an order
parameter, the binder cumulant and the divergence of the overlap
susceptibility. We show that the dynamical behavior of the system is
characterized by aging.Comment: 4 pages including 4 (color) ps figures (all on page 4
The Low Energy Tagger for the KLOE-2 experiment
The KLOE experiment at the upgraded DAFNE e+e- collider in Frascati (KLOE-2)
is going to start a new data taking at the beginning of 2010 with its detector
upgraded with a tagging system for the identification of gamma-gamma
interactions. The tagging stations for low-energy e+e- will consist in two
calorimeters The calorimeter used to detect low-energy e+e- will be placed
between the beam-pipe outer support structure and the inner wall of the KLOE
drift chamber. This calorimeter will be made of LYSO crystals readout by
Silicon Photomultipliers, to achieve an energy resolution better than 8% at 200
MeV.Comment: 4 pages, 5 figures, in the proceedings of "Frontier detectors for
frontier physics", isola d'Elba, Italy, May 200
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