Fractional Oscillator Research Articles

Application of the Explicit Euler Method for Numerical Analysis of a Nonlinear Fractional Oscillation Equation

In this paper, a numerical analysis of the oscillation equation with a derivative of a fractional variable Riemann–Liouville order in the dissipative term, which is responsible for viscous friction, is carried out. Using the theory of finite-difference schemes, an explicit finite-difference scheme (Euler’s method) was constructed on a uniform computational grid. For the first time, the issues of approximation, stability and convergence of the proposed explicit finite-difference scheme are considered. To compare the results, the Adams–Bashford–Moulton scheme was constructed as an experimental method. The theoretical results were confirmed using test examples, the computational accuracy of the method was evaluated, which is consistent with the theoretical one, and the simulation results were visualized. Using the example of a fractional Duffing oscillator, waveforms and phase trajectories, as well as its amplitude–frequency characteristics, were constructed using a finite-difference scheme. To identify chaotic regimes, the spectra of maximum Lyapunov exponents and Poincaré points were constructed. It is shown that an explicit finite-difference scheme can be acceptable under the condition of a step of the computational grid.

Dynamical analysis of fractional oscillator system with cosine excitation utilizing the average method

In this paper, an analytical and numerical algorithm for solving displacement response of fractional oscillator system with cosine excitation is established. The analytical method is to solve steady‐state response and transient response solutions of the system by means of average method and then the total displacement response solution is the sum of steady‐state solution and transient solution. The numerical method is to use the Grünwald–Letnikov definition of fractional derivatives to discretize the fractional differential term in the system and then to reduce the order of the original system. Then, the approximate response solution of the system under the general periodic excitation is obtained by using the Fourier series expansion method and the superposition principle of linear system. Finally, the effectiveness and feasibility of the analytical technique are verified by numerical simulation, and the influence of fractional order, linear damping coefficient and fractional derivative coefficient on the amplitude of the steady‐state response and the total displacement response of the system is analyzed.

Immediate solution for fractional nonlinear oscillators using the equivalent linearized method

The existence of the derivative with a fractional-order in a class of differential equations could lead to complicating the analysis. In this paper, a novel approach has been introduced to facilitate the analysis of the oscillation having fractional-order derivatives and to obtain the analytical solution easily. The present technique is formulated to provide an easy way of understanding. The suggested technique has been utilized to study two examples for illustration. The similitude between the analytical and numerical solution verifies and gives satisfactory precision to the equivalent solution. The new technique is represented to be the best tool for solving the nonlinear oscillation problems in physics and engineering which have a fractional-order.

Different Stochastic Resonances Induced by Multiplicative Polynomial Trichotomous Noise in a Fractional Order Oscillator with Time Delay and Fractional Gaussian Noise

A general investigation on the mechanism of stochastic resonance is reported in a time-delay fractional Langevin system, which endues a nonlinear form multiplicative colored noise and fractional Gaussian noise. In terms of theoretical analysis, both the expressions of output steady-state amplitude and that of the first moment of system response are obtained by utilizing stochastic averaging method, fractional Shapiro and Laplace methods. Due to the presence of trichotomous colored noise, the excitation frequency can induce fresh multimodal Bona fide stochastic resonance, exhibiting much more novel dynamical behaviors than the non-disturbance case. It is verified that multimodal pattern only appears with small noise switching rate and memory damping order. The explicit expressions of critical noise intensity corresponding to the generalized stochastic resonance are given for the first time, by which it is determined that nonlinear form colored noise induces much more of a comprehensive resonant phenomena than the linear form. In the case of slow transfer rate noise, a newfangled phenomenon of double hypersensitive response induced by a variation in noise intensity is discovered and verified for the first time, with the necessary range of parameters for this phenomenon given. In terms of numerical scheme, an efficient and feasible algorithm for generating trichotomous noise is proposed, by which an algorithm based on the Caputo fractional derivative are applied. The numerical results match well with the analytical ones.

SPECTRAL INEQUALITIES FOR COMBINATIONS OF HERMITE FUNCTIONS AND NULL-CONTROLLABILITY FOR EVOLUTION EQUATIONS ENJOYING GELFAND–SHILOV SMOOTHING EFFECTS

AbstractThis work is devoted to the study of uncertainty principles for finite combinations of Hermite functions. We establish some spectral inequalities for control subsets that are thick with respect to some unbounded densities growing almost linearly at infinity, and provide quantitative estimates, with respect to the energy level of the Hermite functions seen as eigenfunctions of the harmonic oscillator, for the constants appearing in these spectral estimates. These spectral inequalities allow us to derive the null-controllability in any positive time for evolution equations enjoying specific regularizing effects. More precisely, for a given index $\frac {1}{2} \leq \mu <1$ , we deduce sufficient geometric conditions on control subsets to ensure the null-controllability of evolution equations enjoying regularizing effects in the symmetric Gelfand–Shilov space $S^{\mu }_{\mu }(\mathbb {R}^{n})$ . These results apply in particular to derive the null-controllability in any positive time for evolution equations associated to certain classes of hypoelliptic non-self-adjoint quadratic operators, or to fractional harmonic oscillators.

Frequency/Laplace domain methods for computing transient responses of fractional oscillators

Although computing the transient response of fractional oscillators, characterized by second-order differential equations with fractional derivatives for the damping term, to external loadings has been studied, most existing methodologies have dealt with cases with either restricted fractional orders or simple external loadings. In this paper, considering complicated irregular, but deterministic, loadings acting on oscillators with any fractional order between 0 and 1, efficient frequency/Laplace domain methods for getting transient responses are developed. The proposed methods are based on pole-residue operations. In the frequency domain approach, “artificial” poles located along the imaginary axis of complex plane are designated. In the Laplace domain approach, the “true” poles are extracted through two phases: (1) a discrete impulse response function (IRF) is produced by taking the inverse Fourier transform of the corresponding frequency response function (FRF) that is readily obtained from the exact transfer function (TF), and (2) a complex exponential signal decomposition method, i.e., the Prony-SS method, is invoked to extract the poles and residues. Once the poles/residues of the system are known, those of the response can be determined by simple pole-residue operations. Sequentially, the response time history is readily obtained. Two single-degree-of-freedom (SDOF) fractional oscillators with rational and irrational derivatives, respectively, subjected to sinusoidal and complicated earthquake loading are presented to illustrate the procedure and verify the correctness of the proposed method. The verification is conducted by comparing the results from both the Laplace and the frequency domain approaches with those from the numerical Duhamel integral method. Furthermore, the proposed method applied to a 3-DOF system with fractional damping is also demonstrated.

A Fractional Oscillator with an Exponential-Power Memory Function

A Fractional Oscillator with an Exponential-Power Memory Function

Fractional Oscillator Radiation

Fractional Oscillator Radiation

Investigation of the Infinite Discrete Levels from Finite Discrete Levels in Position Dependent Mass Quantum Systems

We find quantum systems having finite distinct discrete energy levels can reflect infinite distinct energy levels under suitable form of position dependent mass systems. A model example has been investigated considering the fractional Harmonic Oscillator [6].In addition to this,we also notice the same behaviour in other quantum models. In all the cases, we find finite distinct discrete levels becoming infinite distinct discrete levels under position dependent mass quantum systems without the change in the potential energy.

Frequency Content Preservation in Fractional Multi-Frequency Oscillators Despite Reducing the Number of Energy Storage Elements

Frequency Content Preservation in Fractional Multi-Frequency Oscillators Despite Reducing the Number of Energy Storage Elements

Hyers‐Ulam‐Rassias‐Wright Stability for Fractional Oscillation Equation

In this paper, we consider the nonhomogeneous fractional delay oscillation equation with order σ and introduce a class of control functions, i.e., Wright functions. Next, we apply the Cădariu‐Radu method to prove the existence of a unique solution and Hyers‐Ulam‐Rassias‐Wright stability of the fractional delay oscillation equation. At the end of the article, by an example, we show the application of the obtained results.

On the fractional Kelvin-Voigt oscillator

<abstract> In this paper we discuss the model of fractional oscillator where the inertial and restoring force terms maintains their usual expression but the damping term involves a fractional derivative of Caputo type, the so called fractional Kelvin-Voigt oscillator. The transient solution of this model is given in terms of the so called bivariate Mittag-Leffler function, while the steady-state solution in response to a sinusoidal force involves a 4-variate Mittag-Leffler function. We give numerical examples comparing the solutions for different values of the order $ \alpha $ of the fractional derivative ($ 0 &lt; \alpha \leq 1 $), and compare them with the usual $ \alpha = 1 $ solutions in the underdamped, overdamped and critically damped situations. </abstract>

Stabilization and Destabilization of Fractional Oscillators Via a Delayed Feedback Control

Stabilization and Destabilization of Fractional Oscillators Via a Delayed Feedback Control

A heuristic review on the homotopy perturbation method for non-conservative oscillators

The homotopy perturbation method (HPM) was proposed by Ji-Huan. He was a rising star in analytical methods, and all traditional analytical methods had abdicated their crowns. It is straightforward and effective for many nonlinear problems; it deforms a complex problem into a linear system; however, it is still developing quickly. The method is difficult to deal with non-conservative oscillators, though many modifications have appeared. This review article features its last achievement in the nonlinear vibration theory with an emphasis on coupled damping nonlinear oscillators and includes the following categories: (1) Some fallacies in the study of non-conservative issues; (2) non-conservative Duffing oscillator with three expansions; (3)the non-conservative oscillators through the modified homotopy expansion; (4) the HPM for fractional non-conservative oscillators; (5) the homotopy perturbation method for delay non-conservative oscillators; and (6) quasi-exact solution based on He’s frequency formula. Each category is heuristically explained by examples, which can be used as paradigms for other applications. The emphasis of this article is put mainly on Ji-Huan He’s ideas and the present authors’ previous work on the HPM, so the citation might not be exhaustive.

Stochastic resonance for a fractional linear oscillator with memory-inertia and memory-damping kernels subject to dichotomous time-modulated noise

Stochastic resonance for a fractional linear oscillator with memory-inertia and memory-damping kernels subject to dichotomous time-modulated noise

Sliding Mode Control for Two-Degree-of-Freedom Fractional Zener Oscillator

Abstract Fractional-order derivatives provide a powerful tool for the characterization of mechanical properties of viscoelastic materials. Fractional oscillators are mechanical models of viscoelastically damped structures, the viscoelastic damping of which is described by fractional-order constitutive equations. This paper proposes sliding mode control for a two-degree-of-freedom fractional Zener oscillator. Firstly, a virtual fractional oscillator is generated by means of a state transformation. Then, the total mechanical energy in the virtual oscillator is determined as the sum of the kinetic energy, the potential energy, and the fractional energy. Furthermore, sliding mode control for the fractional Zener oscillator is designed, in which the Lyapunov function is defined by the total mechanical energy. Finally, numerical simulations are conducted to validate the effectiveness of the proposed controllers.

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

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.

Thermal properties of the one-dimensional space quantum fractional Dirac Oscillator

In this paper, we investigate the fractional version of the one-dimensional relativistic oscillators. We apply some important definitions and properties of a new kind of fractional formalism on the Dirac oscillator (DO). By using a semiclassical approximation, the energy eigenvalues have been determined for the oscillator. The obtained results show a remarkable influence of the fractional parameter on the energy eigenvalues. By considering a unique energy spectrum, we present a simple numerical computation of the thermal properties of a defined energy spectrum of a system. the Euler–Maclaurin formula has been used to calculate the partition function and therefore the associated thermodynamics quantities. In addition, the eigensolutions of the fractional Dirac oscillator, based on the factorization method, have been determined.

An accurate numerical technique for fractional oscillation equations with oscillatory solutions

The solution of fractional oscillation equations exhibits highly oscillatory behavior. It is a challenging work to find efficient numerical methods for fractional oscillation equations. The objective of this paper is to develop an accurate numerical technique for fractional oscillation equations with oscillatory solutions. The present method combines the variation‐of‐constants formula with the reproducing kernel function approximation. The merit of our approach is that it can preserve the oscillatory structure of the solution to the considered fractional initial value problems. Illustrative examples clearly show the reliability and efficiency of the approach.

Numerical solution of a class of space fractional nonlinear vibration equations with periodic boundary conditions by the Fourier spectral method

Nonlinear vibration arises everywhere in engineering. So far there is no method to track the exact trajectory of a space fractional nonlinear oscillator; therefore, a sophisticated numerical method is much needed to elucidate its basic properties. For this purpose, a numerical method that combines the Fourier spectral method with the Runge–Kutta method is proposed. Its accuracy and efficiency have been demonstrated numerically. This approach has full physical understanding and numerical access; thus, it can be used to solve many types of nonlinear space fractional partial differential equations with periodic boundary conditions.