Pasquale Nardone | Université libre de Bruxelles (original) (raw)

Papers by Pasquale Nardone

Axioms, Feb 19, 2024

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Axioms, 2024

We propose a new tool for estimating the complexity of a time series: the entropy of difference (... more We propose a new tool for estimating the complexity of a time series: the entropy of
difference (ED). The method is based solely on the sign of the difference between neighboring
values in a time series. This makes it possible to describe the signal as efficiently as prior proposed
parameters, such as permutation entropy (PE) or modified permutation entropy (mPE). Firstly, this
method reduces the size of the sample that is necessary to estimate the parameter value, and secondly
it enables the use of the Kullback–Leibler divergence to estimate the "distance" between the time
series data and random signals.

arXiv (Cornell University), Nov 3, 2014

Here, we propose a new tool to estimate the complexity of a time series: the entropy of differenc... more Here, we propose a new tool to estimate the complexity of a time series: the entropy of difference (ED). The method is based solely on the sign of the difference between neighboring values in a time series. This makes it possible to describe the signal as efficiently as prior proposed parameters such as permutation entropy (PE) or modified permutation entropy (mPE), but (1) reduces the size of the sample that is necessary to estimate the parameter value, and (2) enables the use of the Kullback-Leibler divergence to estimate the distance between the time series data and random signals.

Chaos, Jun 1, 2020

We show, for the first time, the explicit form of the nonlinear partial differential equations (P... more We show, for the first time, the explicit form of the nonlinear partial differential equations (PDEs) subject to the correct boundary conditions that have to be satisfied by transport coefficients having a vanishing skew-symmetric piece. We also report, for the first time, the nonlinear PDEs (with the appropriate boundary conditions) for transport coefficients when the thermodynamic system is subject to two thermodynamic forces. Since the proposed PDEs have been derived without neglecting any term present in the dynamical equations (i.e., the energy, mass, and momentum balance equations), we propose them as a good candidate for describing transport in thermodynamic systems also far from equilibrium (e.g., in the turbulent regime). The preliminary test was carried out by analyzing a concrete example where Onsager's relationships manifestly disagree with experience: magnetically confined Tokamak-plasmas. More specifically, we focus our calculations to compute mass and energy transports in Frascati Tokamak Upgrade-plasmas subject to two thermodynamic forces. We show a good agreement between the theoretical predictions and the experimental data. The aim of this study is to apply our approach to the Divertor Tokamak Test Facility, to be built in Italy, and to the International Thermonuclear Experimental Reactor.

More rigourously, in epidemiology, the basic reproduction number of an infection, R0, is the expe... more More rigourously, in epidemiology, the basic reproduction number of an infection, R0, is the expected number of cases directly generated by one case in a population where all individuals are susceptible to infection in absence of any deliberate intervention in disease transmission (see, for example, [4]).

Proceedings of SPIE, Oct 14, 1986

ABSTRACT Noise-induced transitions in a delay-differential-equation model of an optical bistable ... more ABSTRACT Noise-induced transitions in a delay-differential-equation model of an optical bistable device are studied. In the limit of long delay times, two different mechanisms for the transition process are identified, consistent with the predictions of one-dimensional map models. For small delay times different mechanisms operate. The effects of the statistics of the external noise on the transition process are also investigated.

General Relativity and Gravitation, Aug 1, 1989

A new type of cosmological history which includes large-scale entropy production is proposed. The... more A new type of cosmological history which includes large-scale entropy production is proposed. These cosmologies are based on a reinterpretation of the matter-energy stress tensor in Einstein's equations. This modifies the usual adiabatic energy conservation laws, thereby leading to a possible irreversible matter creation. This creation corresponds to an irreversible energy flow from the gravitational field to the created matter constituents. This new point of view results from the consideration of thermodynamics of open systems in the framework of cosmology. It appears that the usual initial singularity is structurally unstable with respect to irreversible matter creation. The corresponding cosmological history therefore starts from an instability of the vacuum rather than from a singularity. The universe evolves through an inflationary phase. This appears to be an attractor independent of the initial vacuum fluctuation.

ABSTRACT Within the context of semi-classical gravity the instability of Minkowski space-time is ... more ABSTRACT Within the context of semi-classical gravity the instability of Minkowski space-time is a consequence of the non-linear feedback between quantum fluctuations of the matter fields and their space-time geometric response. This leads to a cosmological history finding its roots in an instability rather than in a singularity. The authors present indicating the existence of a close relationship between the assumed initial conformal flatness and the spatial homogeneity of the universe.

Journal of physics, Mar 27, 1998

Physics Letters B, Mar 1, 1983

ABSTRACT Considering a scalar matter-gravitation coupling system, we found that a non-trivial ope... more ABSTRACT Considering a scalar matter-gravitation coupling system, we found that a non-trivial open universe is a solution of the feedback equations at the minkowskian instability point, which like the Casimir effect exhibits a negative energy density and a positive pressure. Boursière IRSIA.

Classical and Quantum Gravity, May 1, 1985

It is proven that the Euclidean de Sitter spacetime is a stable self-consistent cosmology with re... more It is proven that the Euclidean de Sitter spacetime is a stable self-consistent cosmology with respect to the fluctuations which cause the instability of the flat Minkowski quantum vacuum. Moreover, a property is exhibited which strongly suggests that this spacetime is the unique realization of the self-consistent mechanism which creates both the massive constituents of the universe and its large-scale geometrical background.

... INDEPENDENT COMPONENT ANALYSIS OF EVENT-RELATED POTENTIALS C. BUGLI, P. LAMBERT, B. BOULANGER... more ... INDEPENDENT COMPONENT ANALYSIS OF EVENT-RELATED POTENTIALS C. BUGLI, P. LAMBERT, B. BOULANGER, E. LEDENT, A. PEREIRA and P. NARDONE http://www.stat.ucl.ac. be Page 2. ... 3 Eli Lilly and Company, B-1348 Mont-Saint-Guibert, Belgium. ...

General Relativity and Gravitation, Jun 1, 1979

Einstein's equations with a perfect fluid source are subjected to compatibility conditions in the... more Einstein's equations with a perfect fluid source are subjected to compatibility conditions in the context of a space-time that contains symmetric subspaces. These conditions constitute, in some cases, a powerful tool for exhibiting the solutions to a given problem. The Schwarzchild interior metric in conformaUy flat coordinates is derived using these methods.

Classical and Quantum Gravity, Aug 1, 1990

The behavior of the analytic Feynman integral under translation has been studied in the recent wo... more The behavior of the analytic Feynman integral under translation has been studied in the recent work of R. H. Cameron and D. A. Storvick. The purpose of this paper is to continue the development of this transformation theory. In particular, the behavior of the analytic Feynman integral under certain linear transformations is determined and, using this linear transformation theory, a "generalized Schroedinger equation" is solved in terms of an analytic Feynman integral.

Physical review, Apr 1, 1986

%'e study the stability boundaries for the steady and periodic solutions of the Ikeda delaydiffer... more %'e study the stability boundaries for the steady and periodic solutions of the Ikeda delaydifferential equation. In the limit of an infinite delay the differential equation reduces to a nonlinear map. For this map there exist two classes of boundaries: one corresponding to subharmonic cascades and the other either to domains of bistability for steady or periodic solutions or to the emergence of stable periodic solutions from chaos. For a finite delay we show that each of the above boundaries splits into an infinite sequence of secondary boundaries. The crossing of tke secondary boundaries associated with the subharmonic sequence results in the progressive squaring of the periodic solution. The crossing of a secondary boundary of the bistability sequence results in the addition of a frequency in the transient oscillatory relaxation.

Nuclear Physics B, Oct 1, 1980

The creation of the universe is regarded as a self-consistent process in which matter is engender... more The creation of the universe is regarded as a self-consistent process in which matter is engendered by the space-time varying cosmological gravitational field and vice versa. Abundant production can occur only if the mass of the particles so created is of the order of the Planck mass (ffi g-i/2). We conjecture that this is the origin of the fundamental length scale in field theory, as it is encountered, for example, in present efforts towards grand unification. The region of particle production is steady state in character. It ceases when the produced particles decay. The geometry of this steady state is characteristic of a de Sitter space. It permits one to estimate the number of ordinary particles presently observed, N. We find log N ffi O (m~'d~y) ffi O(g-2) ~ O(102), with the usual estimate of g ffi O(10-l) at the Planck length scale. This is not inconsistent with the experimental estimate N~O(109°). After production, cosmological history gives way to the more conventional scheme of free expansion. The present paper is a self-contained account of our view of cosmological history and the production of matter in a varying gravitational field. Special care has been taken to describe the vacuum correctly in the present context and to perform the necessary subtractions of zero-point effects. * For example, the technicolor scheme [4a] or metacolor [4b]. **The formalism for production due to varying gravitational fields is based on the work of Parker and others [6].

Journal of Electromagnetic Waves and Applications, 1996

ABSTRACT Reflection and transmission coefficients for an electromagnetic wave are usually compute... more ABSTRACT Reflection and transmission coefficients for an electromagnetic wave are usually computed using the frequency representation: a monochromatic plane wave decomposition [1-2]. Even though this method is a powerful tool, the physical meaning can be hidden by some mathematical complexity coming from Fourier integrals, complex analysis and matrix manipulation. Furthermore, the Maxwell equations, when the fields are only dependent on x and t, are very simple and can be solved using elementary calculation [3]. It will be shown that the physical propagation mechanism, which includes initial conditions, transmission and reflection, can be completely built up within the space-time, rather than in the frequency domain. This would shed a new light on traditional well known results.

International Journal of Theoretical Physics, Sep 1, 1989

We present a perturbative approach to the equations describing the behavior of a quantum scalar f... more We present a perturbative approach to the equations describing the behavior of a quantum scalar field in a self-consistently generated Robertson-Walker universe. This approach throws new light on the significance of the Minkowskian instability and on the subtraction procedure which shows that a inflation cosmology is a possible future of the Minkowski space.