scholarly journals ON THE POSSIBILITY OF STAGNATION OF FREE OSCILLATIONS OF A NONLINEARLY ELASTIC OSCILLATOR WITH A LINEAR VISCOUS RESISTANCE

2019 ◽  
pp. 38-46
Author(s):  
Olshanskiy Vasyl ◽  
Olshanskiy Stanislav
Keyword(s):  
Differential Equation ◽  
Energy Balance ◽  
Analytical Solution ◽  
Satisfactory Agreement ◽  
Nonlinear Elasticity ◽  
Exact Analytical Solution ◽  
Initial Approximation ◽  
Viscous Resistance ◽  
Free Oscillations ◽  
Approximate Analytical Solutions

The free oscillations of an oscillator with a power-nonlinear elasticity characteristic under the action of linear viscous resistance are considered. Using the energy balance method, which is widespread in mechanics, the calculation of the amplitudes of free damped oscillations is reduced to calculating the roots of an algebraic equation, which has an exact analytical solution only with linear elasticity of the oscillator. In the case of an arbitrary positive indicator of nonlinear elasticity, a numerical solution of the equation is required. For this, the Newton's iterative method was used in the work, which has fast convergence of iterations at an arbitrary initial approximation. According to the results of the analysis of the coefficients of the equation established, that in the case of a rigid characteristic of elasticity, when the nonlinearity is greater than unity, the oscillations are reduced to a finite number of decaying ranges, that is, they are limited in time, and in the case of a soft characteristic of elasticity, when the nonlinearity is less than unity, they continue to infinity, as linear dissipative oscillator. The research is given by the method of energy balance and numerical integration of the differential equation of oscillations on a computer. The work of the force of viscous resistance is calculated approximately using periodic Ateb functions that accurately describe free undamped oscillations in the absence of resistance. As a result, approximate iterative dependences are obtained for calculating the amplitudes of the ranges that decay during movement. The numerical results obtained using approximate formulas and numerical computer integration of the nonlinear Cauchy problem are compared. Their satisfactory agreement was noted. A satisfactory agreement was noted between the results for both hard and soft elastic characteristics, which confirmed the adequacy of approximate analytical solutions to the dynamics problem. The main advantage of the described approximate calculation method is that there is no need to build an analytical solution to the nonlinear differential equation of motion of the oscillator, which is a rather complicated mathematical problem. Furthermore, it made it possible to establish conditions under which the oscillator with a viscous and dry friction resistance have similar oscillation properties.

scholarly journals An analytical approximation of the transient response of a voltage dependent supercapacitor model

2019 ◽  
Vol 39 (3) ◽  
pp. 310-319
Author(s):  
Tomislav Barić ◽  
Hrvoje Glavaš ◽  
Ružica Kljajić
Keyword(s):  
Differential Equation ◽  
Analytical Solution ◽  
Nonlinear Differential Equation ◽  
Exact Analytical Solution ◽  
Initial Response ◽  
Analytical Approximation ◽  
Weight Functions ◽  
Transient Phenomenon ◽  
Voltage Dependent ◽  
Analytical Expressions

Supercapacitors are well known for their voltage dependent capacity. Due to this, it is not possible to obtain the exact analytical solution of the nonlinear differential equation which describes the transient charging and discharging. For this reason, approximations of differential equations must be carried out in order to obtain an approximate analytical solution. The focus of this paper is on a different approach. Instead of approximating the differential equation and obtaining analytical expressions for such approximations, an intuitive approach is chosen. This approach is based on the separation of the initial response from the rest of the transient phenomenon. Both parts of the transient phenomenon are described with adequate functions. Using appropriate weight functions, both functions are combined into a single function that describes the whole transient phenomenon. As shown in the paper, such an approach gives an excellent description of the whole transient. Also, it provides simpler expressions compared to those obtained by approximation of the nonlinear differential equation. With respect to their accuracy, these expressions do not lag behind the aforementioned approach. The validity of the presented analytical expressions was confirmed by comparing their results with those obtained by numerically solving the nonlinear differential equation.

scholarly journals Modified Kudrayshov Method to Solve Generalized Kuramoto–Sivashinsky Equation

2018 ◽  
Author(s):  
Adem Kilicman ◽  
Rathinavel Silambarasan
Keyword(s):  
Differential Equation ◽  
Partial Differential Equation ◽  
Analytical Solution ◽  
Exact Solutions ◽  
Exact Analytical Solution ◽  
Nonlinear Partial Differential Equation ◽  
Complex Structures ◽  
Algebraic Equations ◽  
Uniqueness Of Solutions ◽  
Sivashinsky Equation

The generalized Kuramoto–Sivashinsky equation is investigated using the modified Kudrayshov method for the exact analytical solution. The modified Kudrayshov method converts the nonlinear partial differential equation to algebraic equations, as a result of various steps, which on solving the so obtained equation systems yields the analytical solution. By this way various exact solutions including complex structures are found and drawn their behaviour in complex plane by Maple to compare the uniqueness of solutions.

Load-Supporting Fluid-Filled Cylindrical Membranes

1985 ◽  
Vol 52 (4) ◽  
pp. 913-918 ◽  
Author(s):  
V. Namias
Keyword(s):  
Differential Equation ◽  
Exact Solution ◽  
Analytical Solution ◽  
Boundary Conditions ◽  
Nonlinear Differential Equation ◽  
Entire Range ◽  
Exact Analytical Solution ◽  
Asymptotic Expressions ◽  
Flexible Membranes ◽  
Approximate Expressions

When long cylindrical flexible membranes are filled with a fluid and used to support external weights, the shape they assume and the relevant geometrical and dynamical quantities are governed by a nonlinear differential equation subject to particular boundary conditions. First, a complete and exact analytical solution is obtained for an unloaded membrane. Very accurate approximate expressions are derived directly from the exact solution for the entire range of applied pressures and fluid densities. Next, the nonlinear differential equation is solved exactly under boundary conditions corresponding to the loading of the membrane. Simple asymptotic expressions are also obtained in the limit of large loads.

scholarly journals FREE OSCILLATOR OSCILLATIONS IN THE PRESENCE OF QUADRATIC VISCOUS RESISTANCE AND DRY FRICTION

2020 ◽  
pp. 33-40
Author(s):  
Vasyl Olshanskiy ◽  
Maksym Slipchenko ◽  
Oleksandr Spolnik ◽  
Mykhailo Zamrii
Keyword(s):  
Differential Equation ◽  
Energy Balance ◽  
Nonlinear Differential Equation ◽  
Dry Friction ◽  
Equation Of Motion ◽  
Balance Method ◽  
Forced Oscillations ◽  
Viscous Resistance ◽  
Energy Balance Method ◽  
Damped Oscillations

The article is devoted to the derivation of formulas for calculating the ranges of free damped oscillations of a double nonlinear oscillator. Using the Lambert function and the first integral of the nonlinear differential equation of motion, formulas are derived for calculating the ranges of free damped oscillations of a linearly elastic oscillator under the combined action of the forces of quadratic viscous resistance and Coulomb dry friction. The calculations involve a table of the specified special function of the negative argument. It is shown that the presence of viscous resistance reduces the duration of free oscillations to a complete stop of the oscillator. The set dynamics problem is also approximately solved by the energy balance method, and a numerical integration of the nonlinear differential equation of motion on a computer is carried out. The satisfactory convergence of the numerical results obtained in various ways confirmed the suitability of the derived closed formulas for engineering calculations. In addition to calculating the magnitude of the oscillations, the energy balance method is also used for an approximate solution of the inverse problem of dynamics, by identifying the values of the coefficient of quadratic resistance and dry friction force in the presence of an experimental vibrogram of free damped oscillations. An example of identification is given. This information on friction is needed to calculate forced oscillations, especially under resonance conditions. It is noted that from the obtained results, in some cases, well-known formulas follow, where the quadratic viscous resistance is not associated with dry friction.

scholarly journals Modified Kudrayshov Method to Solve Generalized Kuramoto–Sivashinsky Equation

2018 ◽  
Author(s):  
Rathinavel Silambarasan ◽  
Adem Kilicman
Keyword(s):  
Differential Equation ◽  
Partial Differential Equation ◽  
Analytical Solution ◽  
Complex Plane ◽  
Exact Analytical Solution ◽  
Nonlinear Partial Differential Equation ◽  
Algebraic Equations ◽  
Partial Differential ◽  
Complex Solutions ◽  
Sivashinsky Equation

The generalized Kuramoto–Sivashinsky equation is investigated using the modified Kudrayshov equation for the exact analytical solution. The modified Kudrayshov method converts the nonlinear partial differential equation to algebraic equations by results of various steps which on solving the so obtained equation systems yields the analytical solution. By this way various exact including complex solutions are found and drawn their behaviour in complex plane by Maple to compare the uniqueness of various solutions.

ON THE VIBRATION OF MEMBRANE PARTIALLY PROTRUDING ABOVE THE SURFACE OF LIQUID

2001 ◽  
Vol 09 (04) ◽  
pp. 1599-1609 ◽  
Author(s):  
GEORGE V. FILIPPENKO ◽  
DANIIL P. KOUZOV
Keyword(s):  
Exact Solution ◽  
Analytical Solution ◽  
Exact Analytical Solution ◽  
Free Oscillations ◽  
Mathematical Statement ◽  
Eigen Frequencies ◽  
Vibrating Membrane

The problem of free oscillations of membrane partially submerged into the layer of liquid is considered in the rigorous mathematical statement. The exact analytical solution of the problem is constructed. The eigen frequencies and the eigen functions of vibrating membrane basing on analyses of exact solution are calculated. The influence of liquid's level on eigen frequencies and on eigen functions is analysed.

scholarly journals Numerical Solution of the Bagley-Torvik Equation Using the Integer-Order Derivatives Expansion

2018 ◽  
Vol 6 (2) ◽  
Author(s):  
Afrah Sadiq Hasan
Keyword(s):  
Differential Equation ◽  
Analytical Solution ◽  
Numerical Solution ◽  
Fractional Order ◽  
Infinite Series ◽  
Exact Analytical Solution ◽  
Second Order ◽  
Order Derivative ◽  
Fractional Order Derivative ◽  
Integer Order

Numerical solution of the well-known Bagley-Torvik equation is considered. The fractional-order derivative in the equation is converted, approximately, to ordinary-order derivatives up to second order. Approximated Bagley-Torvik equation is obtained using finite number of terms from the infinite series of integer-order derivatives expansion for the Riemann–Liouville fractional derivative. The Bagley-Torvik equation is a second-order differential equation with constant coefficients. The derived equation, by considering only the first three terms from the infinite series to become a second-order ordinary differential equation with variable coefficients, is numerically solved after it is transformed into a system of first-order ordinary differential equations. The approximation of fractional-order derivative and the order of the truncated error are illustrated through some examples. Comparison between our result and exact analytical solution are made by considering an example with known analytical solution to show the preciseness of our proposed approach.

scholarly journals Study of the Apsidal Precession of the Physical Symmetrical Pendulum

2015 ◽  
Vol 82 (2) ◽  
Author(s):  
Héctor R. Maya ◽  
Rodolfo A. Diaz ◽  
William J. Herrera
Keyword(s):  
Analytical Solution ◽  
Averaging Method ◽  
Exact Analytical Solution ◽  
Spherical Pendulum ◽  
Physical Pendulum ◽  
Variation Of Parameters ◽  
Present Procedure ◽  
Approximate Analytical Solutions ◽  
Jacobi Formalism ◽  
The Ideal

We study the apsidal precession of a physical symmetrical pendulum (PSP) (Allais’ precession) as a generalization of the precession corresponding to the ideal spherical pendulum (ISP) (Airy’s precession). Based on the Hamilton–Jacobi formalism and using the techniques of variation of parameters along with the averaging method, we obtain approximate analytical solutions, in terms of which the motion of both systems admits a simple geometrical description. The method developed in this paper is considerably simpler than the standard one in terms of elliptical functions, and the numerical agreement with the exact solutions is excellent. In addition, the present procedure permits to show clearly the origin of the Airy’s and Allais’ precession, as well as the effect of the spin of the physical pendulum on the Allais’ precession. Further, the method could be extended to the study of the asymmetrical pendulum in which an exact analytical solution is not possible anymore.

scholarly journals An Exact Analytical Solution to the Shallow Water Equations Near Beaches

2017 ◽  
Vol 71 ◽  
pp. 63
Author(s):  
M. Yourdkhani ◽  
Saber Zarrinkamar
Keyword(s):  
Differential Equation ◽  
Analytical Solution ◽  
Shallow Water Equations ◽  
Water Waves ◽  
Jacobi Polynomials ◽  
Exact Analytical Solution ◽  
Second Order ◽  
Shallow Waters ◽  
Order Polynomial ◽  
Linear Counterpart

<p>The nonlinear differential equation governing the dynamics of water waves can be well approximated by a linear counterpart in the case of shallow waters near beaches. The linear equation, which is of second order nature, cannot be exactly solved in many apparently simple cases. In our work, we consider the shape of system as a complete second-order polynomial which contains the constant (step-like), linear and quadratic shapes near the beach. We then apply some novel transformations and transform the problem into a form which can be solved in an exact analytical manner via the powerful Nikiforov-Uvarov technique. The eigenfunctions of the problem are obtained in terms of the Jacobi polynomials and the eigenvalue equation is reported for any arbitrary mode. </p>

HIGHER ORDER COEFFICIENT MEASUREMENTS IN NONLINEAR ABSORPTION PROCESS

2005 ◽  
Vol 14 (01) ◽  
pp. 49-60 ◽  
Author(s):  
S. CHERUKULAPPURATH ◽  
J. L. GODET ◽  
G. BOUDEBS
Keyword(s):  
Differential Equation ◽  
Analytical Solution ◽  
Chalcogenide Glasses ◽  
Higher Order ◽  
Photon Absorption ◽  
Third Order ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Approximate Analytical Solutions ◽  
Basic Differential Equation

Intensity-dependent two-photon absorption in chalcogenide glasses has been experimentally observed. Analytical solution of the basic differential equation giving the intensity at the output of the sample is difficult to obtain in this case. A quasi-analytical solution is provided. Second and third-order nonlinear coefficients are deduced from experimental data using Runge–Kutta numerical integration on data obtained via Z-scan technique. Results of the measured higher-order nonlinear coefficients are given. Comparison of these results with those obtained by various approximate analytical solutions of the differential equation is made.

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