Perikles Papadopoulos

University of West Attica | TEIATH · Department of Electric and Electronics

This work presents a new analysis method for two-symbol symbolic time series based on the time-to-space mapping achieved through a device of current carrying circular rings. An algorithm based on the theory of prime numbers is proposed for the approximate estimation of the stratified magnetic field produced by the aforementioned device. The main pr...

In the present work we propose an algorithm based on the theory of prime numbers for the estimation of the magnetic field in a device of current carrying circular rings. Using the proposed algorithm, the magnetic field can be determined in a very good agreement with that resulting from an algorithm based on the Biot-Savart law. In addition, the pri...

In this paper, we present a new method for successfully simulating the dynamics of COVID-19, experimentally focusing on the third wave. This method, namely, the Method of Parallel Trajectories (MPT), is based on the recently introduced self-organized diffusion model. According to this method, accurate simulation of the dynamics of the COVID-19 infe...

In this work we suggest that the production of bosons (mesons) in a cascade process such as the one provided by the Schwinger and Bjorken models for the quark confinement, can be considered as a natural feedback process. Within this feedback process, a recurrent operator acts on the initial boson field function, which is mathematically expressed by...

This paper presents our study of the presence of the unstable critical point in spontaneoussymmetry breaking (SSB) in the framework of Ginzburg–Landau (G-L) free energy. Through a 3DIsing spin lattice simulation, we found a zone of hysteresis where the unstable critical point continuedto exist, despite the system having entered the broken symmetry...

In this brief, the spontaneous symmetry breaking (SSB) of the φ4 theory in phase space, is studied. This phase space results from the appropriate system of Poincare maps, produced in both the Minkowski and the Euclidean time. The importance of discretization in the creation of phase space, is highlighted. A series of interesting, novel, unknown beh...

In this paper, we consider an initial boundary value problem for a nonlinear Love equation with infinite memory. By combining the linearization method, the Faedo-Galerkin method and the weak compactness method, we prove the local existence and uniqueness of weak solution. The finite time blow up of weak solution is considered.

In this brief, the spontaneous symmetry breaking (SSB) of the $\varphi^4$ theory in phase space, is studied. This phase space results from the appropriate system of Poincare maps, produced in both the Minkowski and the Euclidean time. The importance of discretization in the creation of phase space, is highlighted. A series of interesting, novel, un...

Recently, it has been successfully shown that the temporal evolution of the fraction of COVID-19 infected people possesses the same dynamics as the ones demonstrated by a self-organizing diffusion model over a lattice, in the frame of universality. In this brief, the relevant emerging dynamics are further investigated. Evidence that this nonlinear...

We express the Kirchhoff wave equation in terms of classic field theory. This permits us to introduce the spontaneous symmetry breaking phenomenon in the study of linear structures, such as strings in order to investigate the existence of solitons solutions. We find ϕ⁴ solitons in the space of spatial gradient of lateral displacement of a string. T...

A device consisting of an array of coaxial, identical, circular rings behaves like a solenoid when the ratio of its radius and distance between two successive rings is higher than 1. As this ratio decreases, the device significantly deviates from the solenoid behavior. At the same time, a diffraction-like phenomenon for the magnetic field appears w...

We investigate the asymptotic behavior of solutions for the nonlocal quasilinear hyperbolic problem of Kirchhoff type $$\displaystyle u_{tt} -\phi (x){\| \nabla u(t)\|}^2 \varDelta u + \delta u_t = {|u|}^3 u, \hspace {2 mm} x\in R^N, \hspace {2 mm} t\geq 0, $$ with initial conditions u(x, 0) = u 0(x) and u t(x, 0) = u 1(x), in the case where N ≥ 3,...

The European Union has set targets to reduce the greenhouse gases emissions in total energy consumption as a part of the securing the clean energy initiative and the efforts of carbon emissions reductions of 90%, compared to the 1990 ones, until 2050. The transport sector is particularly exacerbating the above problems. Focusing on their fight, Eur...

The self-organizing mechanism is a universal approach that is widely followed in nature. In this work, a novel self-organizing model describing diffusion over a lattice is introduced. Simulation results for the model's active lattice sites demonstrate an evolution curve that is very close to those describing the evolution of infected European popul...

We investigate about the existence of static solitons solutions in the inverse G-L free energy in phase transitions of {\phi}4 theory. We calculate all the characteristics of these solitons , like localized structure, finite energy and mass . We show that solitons appears in spontaneous symmetry breaking (SSB) phenomenon only if the critical point...

The purpose of this paper is to propose a model of differential equations that will be able to be applied in a bank oligopoly competition case. The differential equations model will be based on Lanchester's combat model, a well-known mathematical theory of war. Due to the fact that an oligopoly of four banks will be examined, the proposed model wil...

The previously introduced model of self-organized criticality, is adapted in the case of a virus-induced epidemic. The study presented in the following lines, highlights the critical value of virus density over a population. For low values of the initial virus density (lower than the critical value) it is proved that the virus-diffusion behavior sa...

European policy on reducing greenhouse gas emissions can be particularly supported by Electric Vehicles' market penetration in the following years. This paper overviews the so far penetration of the Electric Vehicles Technology in Europe and at the same time aims to provide an estimation about the future penetration based on appropriate prognostic...

Bitcoins appeared in the world in 2008 through a paper of “Shatoshi Nakamoto”, obviously a pseudonym. It became operational in the first months of 2009. Since that time more and more users “work” in order to gain the Bitcoins. That work is known as Bitcoins mining. It presupposes the accomplishment of a very big computational load. The basic idea o...

In the recent years the financial debate has focused on the national debt of the countries. These debts consist of different debts to banks, institutions and other countries. In the current work we investigate a method for a mutual national debt cut amongst a group of countries using as a deposit capital equal to the minimum of the debts within the...

We examine the generalized quasilinear Kirchhoff's string equation: utt =-‖A1/2u‖H² Au + f(u), x ∈ ℝN; t ≥ 0, with the initial conditions u(x, 0) = u0(x) and ut(x,0) = u1(x), in the case where N ≥ 3. The purpose of our work is to study the stability of the solution for this equation.

The aim of this paper is to investigate the influence of the lunar period in Greek earthquakes. All earthquakes of magnitude >4 within the decade 2000-2009 have been classified according to their time distance from the full moon and studied with statistical methods.

We discuss the energy decay estimates and the local existence results of the solutions for a nonlocal hyperbolic problem with no dissipation, in the case where N >= 3, and we have a positive function lying in an appropriate space. We prove that we have unique local solution for our problem in the case when the initial energy is small.

The purpose of this paper is to propose a model of differential equations that will be able to be applied in a bank oligopoly competition case. The differential equations model will be based on Lanchester’s combat model, a well-known mathematical theory of war. Due to the fact that an oligopoly of four banks will be examined, the proposed model wil...

We consider a quasilinear Kirchhoff's problem with the initial conditions u(x; 0) = u0(x) and ut(x; 0) = u1(x), in the case where N >= 3; and f(u) is a positive function. The purpose of our work is to study the long time behaviour of the solution of this equation. Here, we prove the existence of a global attractor for this equation in the strong to...

Bitcoin is attracting a steadily increasing interest since its first appearance in 2008. Bitcoin price forecasting would be of great practical interest given its role as a relatively new virtual “currency”. This presupposes the modeling and verification of some kind of relation, causal or not, connecting bitcoin price to other “established” factors...

The textile fabrics are materials of complex structure because their construction is based on interlaced yarns, which are made of twisted fibres. That complexity of the structure is reflected on their mechanical properties. Very often they are characterized by non-linear mechanical response and non-isotropic behaviour. Thus during the testing of th...

The case of moving advertisements (e.g. by offering sample products) is examined in this paper. The range at which a seller acts, follows exponential distribution and affects a moving advertisement's success probability. Moreover the range at which product can be perceived from a consumer is another parameter which affects the probability of succes...

We discuss the energy decay estimates and the local existence results of the solutions for a nonlocal hyperbolic problem. When the initial energy E(u0; u1) which corresponds to the problem, is non-negative and small, there exists a unique local solution in time.

We discuss the asymptotic behaviour of solutions for the nonlocal quasilinear hyperbolic problem of Kirchhoff Type u tt − φ(x)|||u(t)|| 2 ∆u + δu t = |u| a u, x ∈ R N , t ≥ 0 , with initial conditions u(x, 0) = u 0 (x) and u t (x, 0) = u 1 (x), in the case where N ≥ 3, δ ≥ 0 and (φ(x)) −1 = g(x) is a positive function lying in L N/2 (R N)∩L ∞ (R N)...

The estimation of lower bounds for the norms of homogeneous polynomials which are products of linear forms in a Banach space, was obtained by K. Ball in a very precise description in the case where H is a complex Hilbert space with dimension ≥ n. He also managed to obtain a better bound estimate for cn(H) = n −n/2. The above result is taken as a co...

We discuss the asymptotic behaviour of solutions for the nonlocal quasilinear hyperbolic problem of Kirchhoff Type u tt − φ(x)|||u(t)|| 2 ∆u + δu t = |u| a u, x ∈ R N , t ≥ 0 , with initial conditions u(x, 0) = u 0 (x) and u t (x, 0) = u 1 (x), in the case where N ≥ 3, δ ≥ 0 and (φ(x)) −1 = g(x) is a positive function lying in L N/2 (R N)∩L ∞ (R N)...

We discuss the asymptotic behaviour of solutions for the nonlocal quasilinear hyperbolic problem of Kirchhoff Type u tt − φ(x)|||u(t)|| 2 ∆u + δu t = |u| a u, x ∈ R N , t ≥ 0 , with initial conditions u(x, 0) = u 0 (x) and u t (x, 0) = u 1 (x), in the case where N ≥ 3, δ ≥ 0 and (φ(x)) −1 = g(x) is a positive function lying in L N/2 (R N)∩L ∞ (R N)...

In the present paper we introduce a Matlab algorithm in order to study the behaviour of the following discrete infinite Ordinary Differential Equation (O.D.E) system: ˙ u n (t) − δ[g(u n−1 (t) − 2g(u n (t)) + g(u n+1 (t))] + f (u n (t)) = 0, where u n (0) = u n,0. Here we have that δ > 0 constant, f : R → R is a continuous function, n ∈ Z and g is...

In this paper we will prove that if L is a continuous symmetric n-linear form on a Hilbert space and L is the associated continuous n-homogeneous polynomial, then ||L|| = || L||. For the proof we are using a classical generalized inequality due to S. Bernstein for entire functions of exponential type. Furthermore we study the case that if X is a Ba...

We discuss the asymptotic behaviour of solutions for the non-local hyperbolic problemwith initial conditions [Inline formula] and [Inline formula], in the case where [Inline formula] and [Inline formula] is a positive function lying in [Inline formula]. When the initial energy [Inline formula] which corresponds to the problem, is non-negative and s...

The paper is concerned with establishing the links between the approximate GCD of a set of polynomials and the notion of the pseudo-spectrum defined on a set of polynomials. By examining the pseudo-spectrum of the structured matrix we will derive estimates of the area of the approximate roots of the initial polynomial set. We will relate the streng...

We study on the global existence, decay properties and blow-up results of the solution for the following non-degenerate nonlinear wave equation where we have b ≥ 0, p ≥ 0, γ ≥ 1, δ > 0, (x) > 0 for all x and a > 0.

EEG recordings give extremely noisy signals that do not allow classical methods to clearly display such as the existence of power laws or even more so the critical state that is a signature of the normal operation of biological tissues (Contoyiannis et al., Phys Rev Lett 93:098101, 2004; Contoyiannis et al., Nat Hazards Earth Syst Sci 13:125–139, 2...

We study the initial-boundary value problem for the following degenerate non-linear dissipative wave equations of Kirchhoff type: utt - Φ(x){double pipe}∇u(t){double pipe}2γΔu + δut = f(u), x ∈ ℝN, t≥0, with initial conditions u(x,0) = u0(x) and ut(x,0) = u1(x), in the case where N ≥ 3, δ > 0, γ ≥ 1, f(u) is a nonlinear C1 function and Φ(x))-1 = g(...

We consider the quasilinear nonlocal dissipative Kirchhoff String problem u(u)-phi(x) vertical bar vertical bar x Delta u + delta u(t) + f(u) = 0, x is an element of R-N, t >= 0, with the initial conditions u(x, 0) = u(0)(x) and u(t)(x, 0) = u(1)(x), in the case where N >= 3, delta >= 0, f(u) = |u|(a)u for example, and (phi(x))(-1) is an element of...

We study on the initial-bountary value problem for some degenerate non-linear dissipative wave equations of Kirchho type: utt (x)|| 5 u(t)|| 2 u + u t = f(u), x 2 IR N , t 0, with initial conditions u(x,0) = u0(x) and ut(x,0) = u1(x), in the case where N 3, > 0, 1, f(u) = |u| a u with a > 0 and ( (x)) 1 = g(x) is a positive

We study the long time behavior of solutions to the nonlocal quasi- linear dissipative wave equation utt (x)kru(t)k2 u + u t + |u|au = 0, in RN, t 0, with initial conditions u(x,0) = u0(x) and ut(x,0) = u1(x). We consider the case N 3, > 0, and ( (x)) 1 a positive function in LN/2(RN) \ L1(RN). The existence of a global attractor is proved in the s...

We study the long time behavior of solutions to the nonlocal quasilinear dissipative wave equation $$ u_{tt}-phi (x)| abla u(t)|^{2}Delta u+delta u_{t}+|u|^{a}u=0, $$ in $mathbb{R}^N$, $t geq 0$, with initial conditions $ u(x,0) = u_0 (x)$ and $u_t(x,0) = u_1(x)$. We consider the case $N geq 3$, $delta> 0$, and $(phi (x))^{-1}$ a positive function...

We consider the generalized quasilinear dissipative Kirchhoff's String problemwith the initial conditions u(x,0)=u0(x) and ut(x,0)=u1(x), in the case where . The purpose of our work is to study the stability of the initial solution u=0 for this equation using central manifold theory.

We study the asymptotic behaviour of an equation of Kirchhoff’s type on ℝ N . We prove the existence of an absorbing set and the existence of a strong global attractor for this equation. We also give stability results for the generalized equation of Kirchhoff’s type on all of ℝ N .

We discuss the asymptotic behaviour of solutions for the nonlocal quasilinear hyperbolic problem of Kirchhoff Type u tt − φ(x)|| u(t)|| 2 ∆u + δu t = |u| a u, x ∈ IR N , t ≥ 0, with initial conditions u(x, 0) = u 0 (x) and u t (x, 0) = u 1 (x), in the case where N ≥ 3, δ ≥ 0 and (φ(x)) −1 = g(x) is a positive function lying in L N/2 (IR N) ∩ L ∞ (I...

We discuss the asymptotic behaviour of solutions for the non- local quasilinear hyperbolic problem of Kirchho Type utt (x)kru(t)k2 u + u t = |u|au, x 2 RN, t 0, with initial conditions u(x,0) = u0(x) and ut(x,0) = u1(x), in the case where N 3, 0 and ( (x)) 1 = g(x) is a positive function lying in LN/2(RN) \ L1(RN). When the initial energy E(u0,u1),...

We study on the initial-bountary value problem for some degenerate non- linear dissipative wave equations of Kirchho type: utt (x)|| 5 u(t)||2 u + u t = f(u), x 2 IRN, t 0, with initial conditions u(x,0) = u0(x) and ut(x,0) = u1(x), in the case where N 3, > 0, 1, f(u) = |u|au with a > 0 and ( (x)) 1 = g(x) is a positive function lying in LN/2(IRN)...