A homotopy continuation inversion of geoelectrical sounding data

This paper is concerned with the steady state bifurcations of a harmonically excited two-member plane truss system. A two-degree-of-freedom Duffing system having nonlinear fractional derivatives is derived to govern the dynamic behaviors of the truss system. Viscoelastic properties are described by the fractional Kelvin–Voigt model based on the Caputo definition. The combined method of harmonic balance and polynomial homotopy continuation is adopted to obtain steady state solutions analytically. A parametric study is conducted with the help of amplitude-response curves. Despite its seeming simplicity, the mechanical system exhibits a wide variety of structural responses. The primary and sub-harmonic resonances and chaos are found in specific regions of system parameters. The dynamic snap-through phenomena are observed when the forcing amplitude exceeds some critical values. Moreover, it has been shown that, suppression of undesirable responses can be achieved via changing of viscosity of the system.

Download Full-text

Prony systems via decimation and homotopy continuation

Proceedings of the 2014 Symposium on Symbolic-Numeric Computation - SNC '14 ◽

10.1145/2631948.2631961 ◽

2014 ◽

Cited By ~ 1

Author(s):

Dmitry Batenkov

Keyword(s):

Homotopy Continuation

Download Full-text

New collocation path-following approach for the optimal shape parameter using Kernel method

SN Applied Sciences ◽

10.1007/s42452-021-04231-1 ◽

2021 ◽

Vol 3 (2) ◽

Author(s):

Zouhair Saffah ◽

Abdelaziz Timesli ◽

Hassane Lahmam ◽

Abderrahim Azouani ◽

Mohamed Amdi

Keyword(s):

Shape Parameter ◽

Kernel Method ◽

Continuation Method ◽

Path Following ◽

High Order ◽

Homotopy Continuation ◽

Homotopy Continuation Method ◽

Optimal Value ◽

Rbf Kernel ◽

Order Algorithm

AbstractThe goal of this work is to develop a numerical method combining Radial Basic Functions (RBF) kernel and a high order algorithm based on Taylor series and homotopy continuation method. The local RBF approximation applied in strong form allows us to overcome the difficulties of numerical integration and to treat problems of large deformations. Furthermore, the high order algorithm enables to transform the nonlinear problem to a set of linear problems. Determining the optimal value of the shape parameter in RBF kernel is still an outstanding research topic. This optimal value depends on density and distribution of points and the considered problem for e.g. boundary value problems, integral equations, delay-differential equations etc. These have been extensively attempts in literature which end up choosing this optimal value by tests and error or some other ad-hoc means. Our contribution in this paper is to suggest a new strategy using radial basis functions kernel with an automatic reasonable choice of the shape parameter in the nonlinear case which depends on the accuracy and stability of the results. The computational experiments tested on some examples in structural analysis are performed and the comparison with respect to the state of art algorithms from the literature is given.

Download Full-text

Geometric Design of Symmetric 3-RRS Constrained Parallel Platforms

Dynamic Systems and Control, Parts A and B ◽

10.1115/imece2004-59792 ◽

2004 ◽

Cited By ~ 3

Author(s):

Eric Wolbrecht ◽

Hai-Jun Su ◽

Alba Perez ◽

J. Michael McCarthy

Keyword(s):

Geometric Design ◽

Homotopy Continuation ◽

Total Degree ◽

Polynomial Equations ◽

Dimensional Synthesis ◽

Kinematic Synthesis ◽

Real Solutions ◽

Parallel Platform ◽

Three Degree Of Freedom ◽

Serial Chains

The paper presents the kinematic synthesis of a symmetric parallel platform supported by three RRS serial chains. The dimensional synthesis of this three degree-of-freedom system is obtained using design equations for each of three RRS chains obtained by requiring that they reach a specified set of task positions. The result is 10 polynomial equations in 10 unknowns, which is solved using polynomial homotopy continuation. An example is provided in which the direction of the first revolute joint (2 parameters) and the z component of the base and platform are specified as well as the two task positions. The system of polynomials has a total degree of 4096 which means that in theory it can have as many solutions. Our example has 70 real solutions that define 70 different symmetric platforms that can reach the specified positions.

Download Full-text

Free-stream coherent structures in parallel boundary-layer flows

Journal of Fluid Mechanics ◽

10.1017/jfm.2014.282 ◽

2014 ◽

Vol 752 ◽

pp. 602-625 ◽

Cited By ~ 26

Author(s):

Kengo Deguchi ◽

Philip Hall

Keyword(s):

Boundary Layer ◽

Reynolds Number ◽

Coherent Structures ◽

Free Stream ◽

Stokes Equations ◽

Navier Stokes ◽

Homotopy Continuation ◽

Boundary Layer Flows ◽

Navier Stokes Equations ◽

High Reynolds

AbstractOur concern in this paper is with high-Reynolds-number nonlinear equilibrium solutions of the Navier–Stokes equations for boundary-layer flows. Here we consider the asymptotic suction boundary layer (ASBL) which we take as a prototype parallel boundary layer. Solutions of the equations of motion are obtained using a homotopy continuation from two known types of solutions for plane Couette flow. At high Reynolds numbers, it is shown that the first type of solution takes the form of a vortex–wave interaction (VWI) state, see Hall & Smith (J. Fluid Mech., vol. 227, 1991, pp. 641–666), and is located in the main part of the boundary layer. On the other hand, here the second type is found to support an equilibrium solution of the unit-Reynolds-number Navier–Stokes equations in a layer located a distance of $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}O(\ln \mathit{Re})$ from the wall. Here $\mathit{Re}$ is the Reynolds number based on the free-stream speed and the unperturbed boundary-layer thickness. The streaky field produced by the interaction grows exponentially below the layer and takes its maximum size within the unperturbed boundary layer. The results suggest the possibility of two distinct types of streaky coherent structures existing, possibly simultaneously, in disturbed boundary layers.

Download Full-text