Search results for " Linear"

Stochastic resonance in a trapping overdamped monostable system.

2009

The response of a trapping overdamped monostable system to a harmonic perturbation is analyzed, in the context of stochastic resonance phenomenon. We consider the dynamics of a Brownian particle moving in a piecewise linear potential with a white Gaussian noise source. Based on linear-response theory and Laplace transform technique, analytical expressions of signal-to-noise ratio (SNR) and signal power amplification (SPA) are obtained. We find that the SNR is a nonmonotonic function of the noise intensity, while the SPA is monotonic. Theoretical results are compared with numerical simulations.

Resonant activation in piecewise linear asymmetric potentials

2011

7 páginas, 8 figuras.-- PACS number(s): 05.40.−a, 05.45.−a, 02.50.Ey

Fractal

2020

The term fractal was first coined by the Polish-born, French-American mathe- matician Benoît Mandelbrot in the mid 1970s (cf. at least Mandelbrot 1975; Stewart 2010). It comes from the Latin word fractus “which has the same root of fraction and fragment and means “irregular or fragmented” (cf. Mandelbrot 1982: 3, in Emmer 2012: 7). Furthermore “it is related to frangere which means to break" (cf. Mandel- brot 1982: 4, in Emmer 2012: 7). Loosely speaking, a fractal is a mathematical object, such as a curve, or, more generally, as a set, “that displays exact or approx- imate self-similarity on different scales” (cf. at least Birken and Coon 2008: 134). Put in more technical terms, a fractal i…

Geometrie della natura. Matematica ed epistemologia

2004

Characterization of the dynamic behaviour of flax fibre reinforced composites using vibration measurements

2017

International audience; Experimental and numerical methods to identify the linear viscoelastic properties of flax fibre reinforced epoxy (FFRE) composite are presented in this study. The method relies on the evolution of storage modulus and loss factor as observed through the frequency response. Free-free symmetrically guided beams were excited on the dynamic range of 10 Hz to 4 kHz with a swept sine excitation focused around their first modes. A fractional derivative Zener model has been identified to predict the complex moduli. A modified ply constitutive law has been then implemented in a classical laminates theory calculation (CLT) routine.

Determination of dynamic properties of flax fibres reinforced laminate using vibration measurements

2017

International audience; Experimental and numerical methods to identify the linear viscoelastic properties of flax fibre reinforced polymer (FFRP) composite are presented in this study. The method relies on the evolution of storage modulus and loss factor as observed through the frequency response. Free-free symmetrically guided beams were excited in the dynamic range of 10 Hz to 4 kHz with a swept sine excitation focused around their first modes. A fractional derivative Zener model has been identified to predict the complex moduli. A modified ply constitutive law has been then implemented in a classical laminates theory calculation (CLT) routine. Overall, the Zener model fitted the experime…

Quantum gap and spin-wave excitations in the Kitaev model on a triangular lattice

2017

We study the effects of quantum fluctuations on the dynamical generation of a gap and on the evolution of the spin-wave spectra of a frustrated magnet on a triangular lattice with bond-dependent Ising couplings, analog of the Kitaev honeycomb model. The quantum fluctuations lift the subextensive degeneracy of the classical ground-state manifold by a quantum order-by-disorder mechanism. Nearest-neighbor chains remain decoupled and the surviving discrete degeneracy of the ground state is protected by a hidden model symmetry. We show how the four-spin interaction, emergent from the fluctuations, generates a spin gap shifting the nodal lines of the linear spin-wave spectrum to finite energies.

Electrodeposition of CeO2 and Co-Doped CeO2 Nanotubes by Cyclic Anodization in Porous Alumina Membranes

2013

An anodic electrodeposition process is proposed to prepare CeO2 and Co-doped CeO2 nanotubes. Anodic alumina membrane is used as template and linear sweep voltammetry is employed to allow the formation of nanotubes without alumina dissolution. SEM micrographs showed large arrays of well defined and aligned NTs, which resulted to be crystalline soon after deposition according to XRD diffraction patterns and Raman Spectroscopy.

Locally convex quasi *-algebras with sufficiently many *-representations

2012

AbstractThe main aim of this paper is the investigation of conditions under which a locally convex quasi ⁎-algebra (A[τ],A0) attains sufficiently many (τ,tw)-continuous ⁎-representations in L†(D,H), to separate its points. Having achieved this, a usual notion of bounded elements on A[τ] rises. On the other hand, a natural order exists on (A[τ],A0) related to the topology τ, that also leads to a kind of bounded elements, which we call “order bounded”. What is important is that under certain conditions the latter notion of boundedness coincides with the usual one. Several nice properties of order bounded elements are extracted that enrich the structure of locally convex quasi ⁎-algebras.

Functional linear regression with functional rensponse application to prediction of electricity consumption

2008

Functional linear regression model linking observations of a functional response variable with measurements of an explanatory functional variable is considered. The slope function is estimated with a tensor product splines. Some computational issues are addressed by means of a simulation study. This model serves to analyze a real data set concerning electricity consumption in Sardinia. The interest lies in predicting either incoming weekend or incoming weekdays consumption curves if actual weekdays consumption is known.