scholarly journals Comparison of Two Different Analytical Forms of Response for Fractional Oscillation Equation

2021 ◽  
Vol 5 (4) ◽  
pp. 188
Author(s):  
Jun-Sheng Duan ◽  
Di-Chen Hu ◽  
Ming Li
Keyword(s):  
Harmonic Oscillation ◽  
Analytical Form ◽  
Analytical Approximation ◽  
Inverse Laplace Transform ◽  
Damping Term ◽  
Liouville Fractional Derivative ◽  
Infinite Integral ◽  
Negative Exponential ◽  
Oscillation Equation ◽  
Asymptotic Behaviours

The impulse response of the fractional oscillation equation was investigated, where the damping term was characterized by means of the Riemann–Liouville fractional derivative with the order α satisfying 0≤α≤2. Two different analytical forms of the response were obtained by using the two different methods of inverse Laplace transform. The first analytical form is a series composed of positive powers of t, which converges rapidly for a small t. The second form is a sum of a damped harmonic oscillation with negative exponential amplitude and a decayed function in the form of an infinite integral, where the infinite integral converges rapidly for a large t. Furthermore, the Gauss–Laguerre quadrature formula was used for numerical calculation of the infinite integral to generate an analytical approximation to the response. The asymptotic behaviours for a small t and large t were obtained from the two forms of response. The second form provides more details for the response and is applicable for a larger range of t. The results include that of the integer-order cases, α= 0, 1 and 2.

Approximate Solutions of Nonlinear Pendulum with Fractional Damping

2021 ◽  
Author(s):  
Sümeyye Sınır ◽  
Bengi Yıldız ◽  
B. Gültekin Sınır
Keyword(s):  
Multiple Scales ◽  
Mathematic Model ◽  
Approximate Solutions ◽  
Damping Term ◽  
Fractional Damping ◽  
Single Degree Of Freedom ◽  
Fractional Oscillator ◽  
Liouville Fractional Derivative ◽  
Nonlinear Pendulum ◽  
Developing Area

Because of many real problems are better characterized using fractional-order models, fractional calculus has recently become an intensively developing area of calculus not only among mathematicians but also among physicists and engineers as well. Fractional oscillator and fractional damped structure have attracted the attention of researchers in the field of mechanical and civil engineering [1-6]. This study is dedicated mainly a pendulum with fractional viscous damping. The mathematic model of pendulum is a cubic nonlinear equation governing the oscillations of systems having a single degree of freedom, via Riemann-Liouville fractional derivative. The method of multiple scales is performed to solve the equation by assigning the nonlinear and damping terms to the ε-order. Finally, the effects of the coefficient of a fractional damping term on the approximate solution are observed.

Time-domain study of transient fields for a thin circular loop antenna

2002 ◽  
Vol 80 (9) ◽  
pp. 995-1003 ◽  
Author(s):  
S T Bishay ◽  
G M Sami
Keyword(s):  
Time Domain ◽  
Analytical Form ◽  
Loop Antenna ◽  
Inverse Laplace Transform ◽  
Wave Number ◽  
Earth Model ◽  
Circular Loop ◽  
Wave Forms ◽  
Displacement Currents ◽  
The Time Domain

The transient fields in the time-domain of a thin circular loop antenna on a two-layer conducting earth model are expressed in analytical form. In these expressions, the displacement currents both in the two-layer ground and in the air region are taken into consideration. The closed-form expressions of the time-domain are obtained as the inverse Laplace transform of the derived full-wave time-harmonic solution. These time-domain solutions are obtained as a summation of wave-guide modes plus contributions from branch cuts in the complex plane of the longitudinal wave number. Numerical examples are given to indicate the important features in the wave forms of the surface fields due to step and pulsed current excitation. These features provide the means of detecting the earth's stratification, measuring the overburden height, and determining the ratio of the conductivities of the layers. PACS Nos.: 41.20Jb, 42.25Bs, 42.25Gy, 44.05+e

scholarly journals Forced Oscillation Criteria for a Class of Fractional Partial Differential Equations with Damping Term

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Wei Nian Li
Keyword(s):  
Partial Differential Equations ◽  
Differential Equations ◽  
Forced Oscillation ◽  
Smooth Boundary ◽  
Sufficient Conditions ◽  
Normal Vector ◽  
Fractional Partial Differential Equations ◽  
Damping Term ◽  
Partial Differential ◽  
Liouville Fractional Derivative

Sufficient conditions are established for the forced oscillation of fractional partial differential equations with damping term of the form(∂/∂t)(D+,tαu(x,t))+p(t)D+,tαu(x,t)=a(t)Δu(x,t)-q(x,t)u(x,t)+f(x,t),(x,t)∈Ω×R+≡G, with one of the two following boundary conditions:∂u(x,t)/∂N=ψ(x,t),  (x,t)∈∂Ω×R+oru(x,t)=0,  (x,t)∈∂Ω×R+, whereΩis a bounded domain inRnwith a piecewise smooth boundary,∂Ω,R+=[0,∞),  α∈(0,1)is a constant,D+,tαu(x,t)is the Riemann-Liouville fractional derivative of orderαofuwith respect tot,Δis the Laplacian inRn,Nis the unit exterior normal vector to∂Ω, andψ(x,t)is a continuous function on∂Ω×R+. The main results are illustrated by some examples.

scholarly journals Solving the Oscillation Equation With Fractional Order Damping Term Using a New Fourier Transform Method

2017 ◽  
Vol 13 (5) ◽  
pp. 7393-7397
Author(s):  
OZLEM OZTURK MIZRAK
Keyword(s):  
Fourier Transform ◽  
Fractional Derivative ◽  
Fractional Order ◽  
Fourier Transformation ◽  
Cosmic Time ◽  
Damping Term ◽  
Fractional Damping ◽  
Transform Method ◽  
Fourier Transform Method ◽  
Oscillation Equation

We propose an adapted Fourier transform method that gives the solution of an oscillation equation with a fractional damping term in ordinary domain. After we mention a transformation of cosmic time to individual time (CTIT), we explain how it can reduce the problem from fractional form to ordinary form when it is used with Fourier transformation, via an example for 1 < alpha < 2; where alpha is the order of fractional derivative. Then, we give an application of the results.

scholarly journals The Extended Fractional (DξαG/G)-Expansion Method and Its Applications to a Space-Time Fractional Fokas Equation

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Yunmei Zhao ◽  
Yinghui He
Keyword(s):  
Traveling Wave ◽  
Traveling Wave Solutions ◽  
Expansion Method ◽  
Space Time ◽  
Hyperbolic Function ◽  
Fractional Partial Differential Equations ◽  
Exact Analytical Solutions ◽  
Wave Solutions ◽  
Liouville Fractional Derivative ◽  
Negative Exponential

Based on a fractional subequation and the properties of the modified Riemann-Liouville fractional derivative, we propose a new analytical method named extended fractional (DξαG/G)-expansion method for seeking traveling wave solutions of fractional partial differential equations. To illustrate the effectiveness of the method, we discuss a space-time fractional Fokas equation, many types of exact analytical solutions are obtained, and the solutions include hyperbolic function and trigonometric and negative exponential solutions.

scholarly journals The Periodic Solution of Fractional Oscillation Equation with Periodic Input

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Jun-Sheng Duan
Keyword(s):  
Periodic Solution ◽  
Initial Conditions ◽  
Harmonic Oscillation ◽  
Initial Time ◽  
Integer Order ◽  
Periodic Input ◽  
Order Case ◽  
Circular Frequency ◽  
System Frequency ◽  
Oscillation Equation

The periodic solution of fractional oscillation equation with periodic input is considered in this work. The fractional derivative operator is taken as  -∞Dtα, where the initial time is-∞; hence, initial conditions are not needed in the model of the present fractional oscillation equation. With the input of the harmonic oscillation, the solution is derived to be a periodic function of timetwith the same circular frequency as the input, and the frequency of the solution is not affected by the system frequencycas is affected in the integer-order case. These results are similar to the case of a damped oscillation with a periodic input in the integer-order case. Properties of the periodic solution are discussed, and the fractional resonance frequency is introduced.

On the influence of specimen thickness in TEM images of super-conducting vortices

1996 ◽  
Vol 54 ◽  
pp. 724-725
Author(s):  
J. Bonevich ◽  
D. Capacci ◽  
G. Pozzi ◽  
K. Harada ◽  
H. Kasai ◽  
...  
Keyword(s):  
Flux Line ◽  
Analytical Form ◽  
Realistic Model ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Flux Tubes ◽  
Analytical Expression ◽  
Flux Lines ◽  
Normal Core ◽  
Two Parameters

The successful observation of superconducting flux lines (fluxons) in thin specimens both in conventional and high Tc superconductors by means of Lorentz and electron holography methods has presented several problems concerning the interpretation of the experimental results. The first approach has been to model the fluxon as a bundle of flux tubes perpendicular to the specimen surface (for which the electron optical phase shift has been found in analytical form) with a magnetic flux distribution given by the London model, which corresponds to a flux line having an infinitely small normal core. In addition to being described by an analytical expression, this model has the advantage that a single parameter, the London penetration depth, completely characterizes the superconducting fluxon. The obtained results have shown that the most relevant features of the experimental data are well interpreted by this model. However, Clem has proposed another more realistic model for the fluxon core that removes the unphysical limitation of the infinitely small normal core and has the advantage of being described by an analytical expression depending on two parameters (the coherence length and the London depth).

An Analytical Thermodynamic Approach to Friction of Rubber on Ice

2012 ◽  
Vol 40 (2) ◽  
pp. 124-150
Author(s):  
Klaus Wiese ◽  
Thiemo M. Kessel ◽  
Reinhard Mundl ◽  
Burkhard Wies
Keyword(s):  
Coefficient Of Friction ◽  
Liquid Layer ◽  
Contact Area ◽  
Leading Edge ◽  
Viscous Friction ◽  
Analytical Approximation ◽  
Real Contact Area ◽  
Length Scales ◽  
Real Contact ◽  
Ice Surface

ABSTRACT The presented investigation is motivated by the need for performance improvement in winter tires, based on the idea of innovative “functional” surfaces. Current tread design features focus on macroscopic length scales. The potential of microscopic surface effects for friction on wintery roads has not been considered extensively yet. We limit our considerations to length scales for which rubber is rough, in contrast to a perfectly smooth ice surface. Therefore we assume that the only source of frictional forces is the viscosity of a sheared intermediate thin liquid layer of melted ice. Rubber hysteresis and adhesion effects are considered to be negligible. The height of the liquid layer is driven by an equilibrium between the heat built up by viscous friction, energy consumption for phase transition between ice and water, and heat flow into the cold underlying ice. In addition, the microscopic “squeeze-out” phenomena of melted water resulting from rubber asperities are also taken into consideration. The size and microscopic real contact area of these asperities are derived from roughness parameters of the free rubber surface using Greenwood-Williamson contact theory and compared with the measured real contact area. The derived one-dimensional differential equation for the height of an averaged liquid layer is solved for stationary sliding by a piecewise analytical approximation. The frictional shear forces are deduced and integrated over the whole macroscopic contact area to result in a global coefficient of friction. The boundary condition at the leading edge of the contact area is prescribed by the height of a “quasi-liquid layer,” which already exists on the “free” ice surface. It turns out that this approach meets the measured coefficient of friction in the laboratory. More precisely, the calculated dependencies of the friction coefficient on ice temperature, sliding speed, and contact pressure are confirmed by measurements of a simple rubber block sample on artificial ice in the laboratory.

SH-Wave Scattering From the Interface Defect

2017 ◽  
Vol 5 (1) ◽  
pp. 45-50
Author(s):  
Myron Voytko ◽  
◽  
Yaroslav Kulynych ◽  
Dozyslav Kuryliak
Keyword(s):  
Half Space ◽  
Wave Diffraction ◽  
Scattered Field ◽  
Wave Scattering ◽  
Elastic Layer ◽  
Analytical Form ◽  
Structure Parameters ◽  
Sh Wave ◽  
Interface Defect ◽  
Hopf Method

The problem of the elastic SH-wave diffraction from the semi-infinite interface defect in the rigid junction of the elastic layer and the half-space is solved. The defect is modeled by the impedance surface. The solution is obtained by the Wiener- Hopf method. The dependences of the scattered field on the structure parameters are presented in analytical form. Verifica¬tion of the obtained solution is presented.

The Comparison Between the Bayes Estimator and the Maximum Likelihood Estimator of the Reliability Function for Negative Exponential Distribution

2018 ◽  
pp. 439
Author(s):  
Hazim Mansour Gorgees ◽  
Bushra Abdualrasool Ali ◽  
Raghad Ibrahim Kathum
Keyword(s):  
Maximum Likelihood ◽  
Maximum Likelihood Estimator ◽  
Exponential Distribution ◽  
Reliability Function ◽  
Bayes Estimator ◽  
Likelihood Estimator ◽  
Monte Carlo Simulation Technique ◽  
Negative Exponential Distribution ◽  
Negative Exponential ◽  
Better Than

     In this paper, the maximum likelihood estimator and the Bayes estimator of the reliability function for negative exponential distribution has been derived, then a Monte –Carlo simulation technique was employed to compare the performance of such estimators. The integral mean square error (IMSE) was used as a criterion for this comparison. The simulation results displayed that the Bayes estimator performed better than the maximum likelihood estimator for different samples sizes.

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