arXiv subjects

Yiannis Contoyiannis

Publications and source records attributed to Yiannis Contoyiannis.

8 recordsLinked to original sources

arXiv2026

Criticality in memristor devices and the creation of deep memory

In the present work we describe a way to assess memory capability of real devices, while proposing to the engineering community what to pursue to create devices with deep associated memory capability. The study of the signal produced by a real memristor nano-device focused on the description in terms of the Landau ϕ4 theory for the critical phenomena in finite systems. This further allowed the utilization of the property of the anomalous enhancement of the autocorrelation function when a system is on the Spontaneous Symmetry Breaking (SSB), for improving the quantity of the demonstrated memory, while simultaneously maintaining a very good quality, as this is expressed by the stability of the autocorrelation function. In this proof-of-concept case, the morphology of the signal allowed us to impose the appropriate modifications on the signal so that we finally show how to get very close to the characteristics of the SSB and thus achieve our goal to get as close as possible to the ideal behavior of a Memristor that yields deep memory. Finally, we provide proof of the stability of memristor's operation by showing that solitons "follow" as a skeleton structure the experimentally derived time series.

nlin.CD↗

arXiv2021

Post-spontaneous-symmetry-breaking power-laws after a very strong earthquake: Indication for the preparation of a new strong earthquake or not?

It has recently been found that the evolution of the preparation of a strong earthquake (EQ), as it is monitored through fracture-induced electromagnetic emissions (EME) in the MHz band, presents striking similarity with the evolution of a thermal system as temperature drops, since distinct steps of the evolution of the phenomenon of spontaneous symmetry breaking (SSB) can be identified. Here, the study of fracture-induced EME in the MHz band in analogy to thermal systems is extended to the phase of local fracture structures that follow after the SSB (and the occurrence of the main EQ). By comparing fracture-induced MHz EME associated with the strongest EQs (Mw=6.9) that occurred in Greece during the last twenty years with the 3D Ising model, a way to distinguish whether a possible identification of post-SSB power-laws immediately after a very strong EQ is a sign for the preparation of a new strong EQ or not is provided. In the suggested approach, the time series analysis method known as the method of critical fluctuations is used, enhanced by the autocorrelation function, while the role of the latter proves to be decisive.

physics.geo-ph↗

arXiv2019

Pre-earthquake electromagnetic emissions with critical and tricritical behavior before the recent Durrës (Albania) (Mw=6.4, 26-11-2019) and Chania (Greece) (Mw=6.1, 27-11-2019) earthquakes

In this brief report we present evidence for the dynamics of the earthquake (EQ) preparation processes that led to two strong events (Mw>6) that took place in Durrës (Albania) and Chania (West-Crete, Greece) on 26 and 27-11-2019, respectively. Specifically, MHz fracto-electromagnetic emissions (EME) recorded by our telemetric stations presented critical fluctuations prior to each one of these EQs. Subsequently, the EME possibly related to each one of these EQs evolved differently towards the occurrence of the EQ event: the ones possibly related to Chania EQ departed from critical state according to the symmetry breaking phenomenon, while the ones possibly related to Durrës EQ departed from critical state according to the tricritical crossover phenomenon. The analysis was performed by means of the method of critical fluctuations (MCF).

physics.geo-ph↗

arXiv2019

Applying the Method of Critical Fluctuations on Human Electrocardiograms

In this work we apply the Method of Critical Fluctuations (MCF)on human Electrocardiogram (ECG) time-series. The method is able to reveal critical characteristics, in terms of physical behavior, in experimentally recorded signals. Using the concept of criticality as basic criterion for the characterization of the recorded ECG as that of a healthy person, we find a 100% verification of the characterization Myocardial infarction. In contrary in the cases of the characterization Healthy control we find a 88% agreement. We also consider the autocorrelation function for the ECG time-series which obeys optimally the criteria of criticality and we observe the appearance of specific characteristic symmetries in the corresponding profile.

physics.med-ph↗

arXiv2019

Neurobiological reality simulation through an Artificial Neural Network at criticality

An artificial neural network (ANN) based on fundamental principles of physics can simulate the operation of neurobiological reality of membrane potential as well as the properly defined order parameter. This ANN operates in conditions of criticality and simulates the behavior of an excitatory biological neuron, especially the relaxation phase where the critical fluctuations of biological neuron appear. These critical fluctuations can not be explained by the Hodgkin-Huxley (H-H) model. A proposal for the origin of these fluctuations is being discussed.

physics.bio-ph↗

arXiv2019

Two Dimensional Poincare Maps constructed through Ginzburg-Landau Theory of critical phenomena in Physics

Based on the saddle point approximation in G-L theory of the critical phenomena we construct two-dimensional Poincare maps which describe the symmetry breaking (SB) and the tricritical crossover phenomenon in Physics. The phase space diagrams of these maps are in agreement with the theoretical predictions. A correction in these maps close to the critical point for small values of the order parameter is attempted. Finally we demonstrate that numerical experiments verify the correctness of these maps.

cond-mat.stat-mech↗

arXiv2019

Self-Similarity and Criticality in the Boson (pions) field produced according to dynamic cascade models

In this work we reveal that the inside-outside dynamic model for the production of fermion-antifermion pair (or quark-antiquark in QCD), is an out of equilibrium process. Properties of a complex system as the self-similarity and the critical point of a continuous phase transition in equilibrium appear. In this work we show that this is accomplished imposing a type of mapping process through a self-composition operator on a QED_2 bosons (or pions) field.

hep-ph↗

arXiv2019

The degeneration of critical point in Z(3)spin system. A proposal for QCD confinement-deconfinement phase transition in the color space

The problem of the phase transition of a Z(3) spin system is a complex issue. A numerical simulation in the framework of the mean field theory using the Metropolis algorithm reveals: (a) the existence of second order phase transition with a degenerated critical point which could be considered as a state of resonance (b) hysteresis phenomena which are accompanied with tricritical crossover around the end point of first order transition. Based on these results we propose a scenario about confinement-deconfinement phase transition in SU(3) symmetry of color QCD which, as it is known, has the same center with Z(3) spin system symmetry.

hep-lat↗