3,405 research outputs found
Hybrid protoneutron stars within a static approach
We study the hadron-quark phase transition in the interior of protoneutron
stars. For the hadronic sector, we use a microscopic equation of state
involving nucleons and hyperons derived within the finite-temperature
Brueckner-Bethe-Goldstone many-body theory, with realistic two-body and
three-body forces. For the description of quark matter, we employ the MIT bag
model both with a constant and a density-dependent bag parameter. We calculate
the structure of protostars within a static approach. In particular we focus on
a suitable temperature profile, suggested by dynamical calculations, which
plays a fundamental role in determining the value of the minimum gravitational
mass. The maximum mass instead depends only upon the equation of state
employed.Comment: 5 pages, 3 figures, Prepared for XI Convegno su Problemi di Fisica
Nucleare Teorica (Cortona 2006), Cortona, Italy, 11-14 Oct 200
Explicit Reference Governor for Continuous Time Nonlinear Systems Subject to Convex Constraints
This paper introduces a novel closed-form strategy that dynamically modifies
the reference of a pre-compensated nonlinear system to ensure the satisfaction
of a set of convex constraints. The main idea consists of translating
constraints in the state space into constraints on the Lyapunov function and
then modulating the reference velocity so as to limit the value of the Lyapunov
function. The theory is introduced for general nonlinear systems subject to
convex constraints. In the case of polyhedric constraints, an explicit solution
is provided for the large and highly relevant class of nonlinear systems whose
Lyapunov function is lower-bounded by a quadratic form. In view of improving
performances, further specializations are provided for the relevant cases of
linear systems and robotic manipulators.Comment: Submitted to: IEEE Transactions on Automatic Contro
La "Biblioteca" romanistica di Flaminio Mancaleoni
Sulla biblioteca di Flaminio Mancaleoni donata all'Istituto giuridico dell'UniversitĂ di Sassari, oggi Dipartimento di Scienze giuridiche
The authorship of the principle of inertia
According to some currents of modern historiography, Galilei's propensity for circular motion would have led him to consider this and not rectilinear motion as “natural motion”; therefore the principle of inertia could not be fully attributed to Galileo, which he would never have formulated. The question of the authorship of the principle of inertia certainly weighs on both nationalistic elements and returns of antigaleleism, while the question of its not explicit formulation as a principle is due to ignorance of the type of organization that Galileo intended to give to the exposition of his physics. The author, after having hinted at possible prodromes of the principle of inertia and having reported the adverse opinions of illustrious historians of science (A. Koyré, I. B. Cohen, P. M. Duhem, P. Rossi, G. Holton), through a careful analysis of the Galilean writings, conducted on the digital versions with the help of text analysis programs, firmly reaffirms Galileo's authorship of the principle of inertia and the consequent principle of classical relativity
The authorship of the Principle of Inertia
According to some currents of modern historiography, Galilei's propensity for circular motion would have led him to consider this and not rectilinear motion as “natural motion”; therefore the principle of inertia could not be fully attributed to Galileo, which he would never have formulated. The question of the authorship of the principle of inertia certainly weighs on both nationalistic elements and returns of antigaleleism, while the question of its not explicit formulation as a principle is due to ignorance of the type of organization that Galileo intended to give to the exposition of his physics. The author, after having hinted at possible prodromes of the principle of inertia and having reported the adverse opinions of illustrious historians of science (A. Koyré, I. B. Cohen, P. M. Duhem, P. Rossi, G. Holton), through a careful analysis of the Galilean writings, conducted on the digital versions with the help of text analysis programs, firmly reaffirms Galileo's authorship of the principle of inertia and the consequent principle of classical relativity
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