Massimo Materassi

Massimo Materassi
Italian National Research Council | CNR · Institute for Complex Systems ISC

PhD

About

106
Publications
12,874
Reads
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937
Citations
Additional affiliations
September 2008 - April 2009
University of Florence
Position
  • Professor
June 2004 - December 2004
Polish Academy of Sciences
Position
  • PostDoc Position
May 2001 - June 2004
Italian National Research Council
Position
  • Researcher

Publications

Publications (106)
Article
Full-text available
In 1982 in a series of works Vielliefosse [1, 2] discussed a nonlinear homogeneous evolution equation for the velocity gradient tensor in fluid dynamics. Later Cantwell [3] extended this formalism to the non-homogeneous case including the effects of viscous diffusion and cross derivatives of pressure field. Here, we derive the evolution equations o...
Article
In 1982 in a series of works Vielliefosse [1, 2] discussed a nonlinear homogeneous evolution equation for the velocity gradient tensor in fluid dynamics. Later Cantwell [3] extended this formalism to the non-homogeneous case including the effects of viscous diffusion and cross derivatives of pressure field. Here, we derive the evolution equations o...
Presentation
Full-text available
Significant evidence of ionosphere and magnetosphere disturbance in connection to intense seismic events have been detected since two decades. It is generally believed that the energy transfer can be due to Acoustic Gravity Waves (AGW) excited at ground level by the earthquakes. In spite of the statistical evidence of the detected perturbations, th...
Article
Full-text available
Ionospheric medium fluctuations are detected at various spatial and temporal scales. Plasma irregularities encountered crossing high latitude current systems can be extremely thin and therefore, unlikely to identify with standard detectors. This work aims to show plasma layer features obtained by electric field instrument on-board the Chinese Seism...
Presentation
Full-text available
The short-term prediction of earthquakes is an essential issue connected with human life protection and related social and economics matter. Recent papers have provided some evidence of the link between the lithosphere, lower atmosphere, and ionosphere, even though with marginal statistical evidence. The basic coupling hypothesized being via atmosp...
Article
Full-text available
Significant evidence of ionosphere disturbance in connection to intense seismic events have been detected since two decades. It is generally believed that the energy transfer can be due to Acoustic Gravity Waves (AGW) excited at ground level by the earthquakes. In spite of the statistical evidence of the detected perturbations, the coupling between...
Article
Full-text available
We consider networks of dynamical units that evolve in time according to different laws, and are coupled to each other in highly irregular ways. Studying how to steer the dynamics of such systems towards a desired evolution is of great practical interest in many areas of science, as well as providing insight into the interplay between network struc...
Article
In this brief work we present a novel approach to the logistic dynamics of populations and epidemic spreading that can take into account of the complex nature of such a process in several real situations, where due to different agents the dynamics is no longer characterized by a single characteristic timescale, but conversely by a distribution of t...
Article
Full-text available
The short-term prediction of earthquakes is an essential issue connected with human life protection and related social and economic matters. Recent papers have provided some evidence of the link between the lithosphere, lower atmosphere, and ionosphere, even though with marginal statistical evidence. The basic coupling is hypothesized as being via...
Article
Full-text available
Algorithms based on Empirical Mode Decomposition (EMD) and Iterative Filtering (IF) are largely implemented for representing a signal as superposition of simpler well-behaved components called Intrinsic Mode Functions (IMFs). Although they are more suitable than traditional methods for the analysis of nonlinear and nonstationary signals, they could...
Presentation
Full-text available
Ionospheric medium fluctuations are detected at various spatial and temporal scales. Plasma irregularities encountered crossing high latitude current systems can be extremely thin and, therefore, unlikely to identify with standard detectors. In fact, Langmuir probes (Lp) on board LEO satellites usually need some seconds to collect currents from pla...
Article
Some ideas are presented about a geometric motivation of the apparent capacity of generalized logistic equations to describe the outbreak of quite many epidemics, possibly including that of the COVID-19 infection. This interpretation pivots on the complex, possibly fractal, structure of the locus describing the “contagion event set”, and on what ca...
Article
The dynamical variables ψ of a classical system, undergoing stochastic stirring forces, satisfy equations of motion with noise terms. Hence, these ψ show a stochastic evolution themselves. The probability of each possible realization of ψ within a given time interval, arises from the interplay between the deterministic parts of dynamics and the sta...
Article
Full-text available
Some ideas are presented about a geometric motivation of the apparent capacity of generalized logistic equations to describe the outbreak of quite many epidemics, possibly including that of the COVID-19 infection. This interpretation pivots on the complex, possibly fractal, structure of the locus describing the “contagion event set”, and on what ca...
Preprint
Full-text available
Some ideas are presented about the physical motivation of the apparent capacity of generalized logistic equations to describe the outbreak of the COVID-19 infection, and in general of quite many other epidemics. The main focuses here are: the complex, possibly fractal, structure of the locus describing the “contagion event set”; what can be learnt...
Preprint
Full-text available
We consider networks of dynamical units that evolve in time according to different laws, and are coupled to each other in highly irregular ways. Studying how to steer the dynamics of such systems towards a desired evolution is of great practical interest in many areas of science, as well as providing insight into the interplay between network struc...
Article
Full-text available
We analyze the amplitude scintillation on L-band signals over San Miguel de Tucumán (Argentina), focusing on the multi-scale variability and speculating on the possible relationship between forcing factors from the geospace and the ionospheric response. The site is nominally located below the expected position of the southern crest of the Equatoria...
Preprint
Full-text available
The concept of stochastic Lagrangian and its use in statistical dynamics is illustrated theoretically, and with some examples. Dynamical variables undergoing stochastic dierential equations are stochastic processes themselves, and their realization probability functional within a given time interval arises from the interplay between the determinist...
Poster
Full-text available
The evaluation of the external origin contribution (BEXT and EEXT) in geomagnetic field satellite ob-servations in the near Earth location (1.2 RE<R<1.5 RE; RE being the Earth radius) during active magnetic conditions is one of the key problem in the Space Weather context. We propose an inno-vative algorithm able to discriminate the external from t...
Article
In order to construct an analytical model of evolution for the plasma structures in the ionospheric Equatorial Spread F, an attempt is presented to include the plasma perturbations “seeding” the instabilities that cause the Equatorial Spread F in a theoretically consistent way. This is done assuming that the local discrepancies from quasi neutralit...
Preprint
Full-text available
Article
Full-text available
This work aims at showing how analysis techniques, designed to highlight the multi-scale structure of a signal, may be of help in describing fluctuations of the ionospheric medium. In particular, the technique used here is the ALIF (Adaptive Local Iterative Filter). We have applied ALIF to the characterisation of plasma irregularities in the equato...
Preprint
Full-text available
In order to construct an analytical model of evolution for the plasma structures in the ionospheric Equatorial Spread F, an attempt is presented to include the plasma perturbations seeding the instabilities that cause the Equatorial Spread F in a theoretically consistent way. This is done assuming that the local discrepancies from quasi neutrality...
Poster
Full-text available
Introduction. Birkeland currents (field-aligned currents-FACs) flow along magnetic field lines to connect magnetospheric current systems to the high latitudes ionospheric currents. Within the polar cap, tail-shape magnetic field lines are tilted antisunward by the flow of the solar wind, whereas in the return flow region field lines are tilted sunw...
Conference Paper
Full-text available
The evaluation of the external origin contribution (BEXT and EEXT) in geomagnetic field satellite observations in the near Earth location (1.2 RE<R<1.5 RE; RE being the Earth radius) during active magnetic conditions is one of the key problem in the Space Weather context. We propose an innovative algorithm able to discriminate the external from the...
Preprint
Full-text available
Metriplectic dynamics couple a Poisson bracket of the Hamiltonian description with a kind of metric bracket, for describing systems with both Hamiltonian and dissipative components. The construction builds in asymptotic convergence to a preselected equilibrium state. Phenomena such as friction, electric resistivity, thermal conductivity and collisi...
Preprint
Full-text available
Metriplectic dynamics couple a Poisson bracket of the Hamiltonian description with a kind of metric bracket, for describing systems with both Hamiltonian and dissipative components. The construction builds in asymptotic convergence to a preselected equilibrium state. Phenomena such as friction, electric resistivity, thermal conductivity and collisi...
Conference Paper
Full-text available
Many real life signals, and in particular in the space physics domain, exhibit variations across different temporal scales. Hence, their statistical momenta may depend on the time scale at which the signal is studied. To identify and quantify such variations, a time-frequency analysis has to be performed on these signals. The dependence of the stat...
Article
A dynamical system defined by a metriplectic structure is a dissipative model characterized by a specific pair of tensors, which defines the Leibniz brackets. Generally, these tensors are Poisson brackets tensor and a symmetric metric tensor that models purely dissipative dynamics. In this paper, the metriplectic system describing a simplified two-...
Article
Full-text available
The metriplectic formalism couples Poisson brackets of the Hamiltonian description with metric brackets, for describing systems with both Hamiltonian and dissipative components. The construction builds in asymptotic convergence to a preselected equilibrium state. Phenomena such as friction, electric resistivity, thermal conductivity and collisions...
Article
Many real life signals, and in particular in the space physics domain, exhibit variations across different temporal scales. Hence, their statistical momenta may depend on the time scale at which the signal is studied. To identify and quantify such variations, a time-frequency analysis has to be performed on these signals. The dependence of the stat...
Poster
Full-text available
Analysis of the radio scintillation and ionospheric fluctuation data at low latitude focusing on the time and space multi-scale variability and on the causal relationship between forcing factors from the SW environment and the ionospheric response.
Article
Full-text available
Scavenging is ubiquitous in nature, but its implications have rarely been investigated. We used camera traps on wolf kills to investigate the role of scavenging on predator and multiprey dynamics in a northern Apennine system in Italy. In contrast to North American systems, the omnivorous wild boar successfully competes with wolves for the meat of...
Article
Full-text available
The metriplectic formalism couples Poisson brackets of the Hamiltonian description with metric brackets for describing systems with both Hamiltonian and dissipative components. The construction builds in asymptotic convergence to a preselected equilibrium state. Phenomena such as friction, electric resistivity, thermal conductivity and collisions i...
Article
WAM is realized making use of the plasma density data collected via the retarding potential analyser on board the Dynamics Explorer 2 spacecraft, capable to model the scintillation climatology over the northern hemisphere high latitude ionosphere. More recently, WAM has been tuned to model the ionospheric scintillations also over the equatorial lat...
Conference Paper
Full-text available
Radio power scintillation, namely highly irregular fluctuations of the power of trans-ionospheric GNSS signals, is the effect of ionospheric plasma turbulence. The scintillation patterns on radio signals crossing the medium inherit the ionospheric turbulence characteristics of inter-scale coupling, local randomness and large time variability. On th...
Conference Paper
Full-text available
Nonlinear and nonstationary signals are ubiquitous in real life. Their decomposition and analysis is of crucial importance in many research fields. Traditional techniques, like Fourier and wavelet Transform have been proved to be limited in this context. In the last two decades new kind of nonlinear methods have been developed which are able to unr...
Article
In this work the effects of kleptoparitism in a multi-trophic food-web, in which an omnivorous species scavenges the kills of a top predator, are investigated. Scavengers are assumed to be able to steal predators’ kills by direct interference and aggression. The amount of prey shared depends on the relative competitive abilities of omnivores and pr...
Article
Full-text available
This lecture is a short review on the role entropy plays in those classical dissipative systems whose equations of motion may be expressed via a Leibniz Bracket Algebra (LBA). This means that the time derivative of any physical observable f of the system is calculated by putting this f in a “bracket” together with a “special observable” F, referred...
Conference Paper
Full-text available
Highly irregular fluctuations of the power of trans-ionospheric GNSS signals, namely radio power scintillation, are, at least to a large extent, the effect of ionospheric plasma turbulence, a by-product of the non-linear and non-stationary evolution of the plasma fields defining the Earth’s upper atmosphere. One could expect the ionospheric turbule...
Article
In this work we discuss an application of the Tetrad Dynamics approach, a stochastic dynamical theory already introduced in hydrodynamic turbulence, to incompressible magneto-hydrodynamics. This theoretical framework is capable of taking into account some crucial aspects of turbulent plasmas, namely, (i) its material nature, which is stressed throu...
Conference Paper
Full-text available
This lecture is a short review on the role entropy plays in dissipative dynamics formulated in terms of Leibniz bracket algebræ (LBA). While conservative dynamics is given an LBA formulation in the Hamiltonian framework, with total energy H generating the motion via classical Poisson brackets or quantum commutation brackets, an LBA formulation can...
Article
Full-text available
In the last decade, significant advances have been presented for the theoretical characterization and experimental techniques used to measure and model all of the components of the velocity gradient tensor in the framework of fluid turbulence. Here, we attempt the evaluation of the small-scale velocity gradient tensor for a case study of space plas...
Article
Full-text available
The dynamics of dissipative fluids in Eulerian variables may be derived from an algebra of Leibniz brackets of observables, the metriplectic algebra, that extends the Poisson algebra of the frictionless limit of the system via a symmetric semidefinite component, encoding dissipative forces. The metriplectic algebra includes the conserved total Hami...
Conference Paper
Full-text available
The dynamics of dissipative fluids in Eulerian variables may be derived from an algebra of Leibniz brackets of observables, the metriplectic algebra, that extends the Poisson algebra of the frictionless limit of the sytem via a symmetric semidefinite component, that generates dissipative forces. The metriplectic algebra includes the conserved total...
Article
Full-text available
The use of transfer entropy has proven to be helpful in detecting which is the verse of dynamical driving in the interaction of two processes, X and Y . In this paper, we present a different normalization for the transfer entropy, which is capable of better detecting the information transfer direction. This new normalized transfer entropy is applie...
Poster
Full-text available
The Earth's plasmasphere variability is a consequence of the Sun's forcing, determining our planet's space weather. Plasmaspheric dynamics could be entirely caught only by studying together global and local proxies of the state of this extended system.
Conference Paper
Full-text available
The ISIS project (Inter-Satellite & In Situ plasmaspheric monitoring and modelling) aimed to design a system for the continuous monitoring of the Earth’s plasmasphere based on the future Galileo satellites. The ISIS Team proposed new experimental facilities on board of future generation Galileo satellites, designed to realize inter-satellite and i...
Article
Full-text available
We describe the introduction of the first all-sky imaging system for low-light-level optical observations of the disturbed ionosphere over mid-latitude Europe. Using 6300 Å auroral emissions that come from the 200-400 km altitude range, we demonstrate that sub-visual optical patterns spanning the European continent can be obtained from a single sit...
Article
The formulation of Action Principles in Physics, and the introduction of the Hamiltonian framework, reduced dynamics to bracket algebra of observables. Such a framework has great potentialities, to understand the role of symmetries, or to give rise to the quantization rule of modern microscopic Physics. Conservative systems are easily algebrized vi...
Article
Certain modern radio systems that rely on trans-ionospheric propagation require knowledge of the changes in the ionosphere that can be characterised by changes in total electron content (TEC). An important cause of these TEC fluctuations is travelling ionosphere disturbances (TIDs). Temporal variations of European mid-latitude TEC measurements obta...
Article
The metriplectic framework, which permits to formulate an algebraic structure for dissipative systems, is applied to visco-resistive Magneto-Hydrodynamics (MHD), adapting what had already been done for non-ideal Hydrodynamics (HD). The result is obtained by extending the HD symmetric bracket and free energy to include magnetic field dynamics and re...
Poster
Full-text available
The extension and the local plasma properties of the Earth's plasmasphere are governed by the interaction with the magnetosphere above (in turn forced by the solar wind) and by the matter exchange and electromagnetic coupling with the underlying ionosphere. The variability of the plasmasphere, as a consequence of the Sun's forcing, defines our plan...
Article
Full-text available
One of the most interesting aspects of the global magnetospheric response to solar wind changes is the relationship between storms and substorms. Here we present new results on the relationship between these two different classes of magnetospheric phenomena by approaching the problem on the side of information theory. Using the Auroral Electrojet A...
Article
Transionospheric radio signals may experience fluctuations in their amplitude and phase due to irregularity in the spatial electron density distribution, referred to as scintillation. Ionospheric scintillation is responsible for transionospheric signal degradation that can affect the performance of satellite based navigation systems. Usually, the s...
Article
Full-text available
It is rather well recognized that the global dynamics of the Sun–Earth relationship involves complex nonlinear phenomena. Here we present a preliminary attempt to characterize the influence and the timing of the solar magnetic activity on the near-Earth environment, based on quite novel tools based on concepts from information theory.In detail, we...
Article
Full-text available
Magnetohydrodynamics in two dimensions is of particular use in all those contexts where the plasma is strongly magnetized in a given direction, so that its relevant dynamics takes place almost only on the plane perpendicular to the strong 'guiding' field. This approach, referred to as reduced MHD, is of great use for describing the fusion plasma in...
Article
Full-text available
Magneto-hydrodynamics in two dimensions, with finite resistivity and viscosity, is of a certain use in all those contexts where the plasma is strongly magnetized in a given direction, so that its relevant dynamics takes place almost only on the plane perpendicular to the strong 'guiding' field. This approach is sometimes called reduced MHD. In turb...
Article
Full-text available
Radar data collected at an experimental facility arranged on purpose suggest that the footprint of atmospheric turbulence might be encoded in the radar signal statistics. Radar data probability distributions are calculated and nicely fitted by a one-parameter family of generalized Gumbel (GG) distributions, Ga. A relation between the wind strength...