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991.
In this paper, the nonlinear free vibration of the nanotube with damping effects is studied. Based on the nonlocal elastic theory and Hamilton principle, the governing equation of the nonlinear free vibration for the nanotube is obtained. The Galerkin method is employed to reduce the nonlinear equation with the integral and partial differential characteristics into a nonlinear ordinary differential equation. Then the relation is solved by the multiple scale method and the approximate analytical solution is derived. The nonlinear vibration behaviors are discussed with the effects of damping, elastic matrix stiffness, small scales and initial displacements. From the results, it can be observed that the nonlinear vibration can be reduced by the matrix damping. The elastic matrix stiffness has significant influences on the nonlinear vibration properties. The nonlinear behaviors can be changed by the small scale effects, especially for the structure with large initial displacement. 相似文献
992.
Regularized versions of continuous analogues of Newton's method and modified Newton's method for obtaining approximate solutions to a nonlinear ill-posed operator equation of the form F(u) = f, where F is a monotone operator defined from a Hilbert space H into itself, have been studied in the literature. For such methods, error estimates are available only under Hölder-type source conditions on the solution. In this paper, presenting the background materials systematically, we derive error estimates under a general source condition. For the special case of the regularized modified Newton's method under a Hölder-type source condition, we also carry out error analysis by replacing the monotonicity of F by a weaker assumption. This analysis facilitates inclusion of certain examples of parameter identification problems, which was not possible otherwise. Moreover, an a priori stopping rule is considered when we have a noisy data f δ instead of f. This rule yields not only convergence of the regularized approximations to the exact solution as the noise level δ tends to zero but also provides convergence rates that are optimal under the source conditions considered. 相似文献
993.
T. Benincasa 《Numerical Functional Analysis & Optimization》2013,34(3-4):199-213
The paper presents a proof of the convergence for an iterative scheme of fractional steps type associated to the phase-field transition system (a nonlinear parabolic system) with non-homogeneous Cauchy–Neumann boundary conditions. The advantage of such method consists in simplifying the numerical computation necessary to be done in order to approximate the solution of a nonlinear parabolic system. On the basis of this approach, a numerical algorithm in the two dimensional case is introduced and an industrial implementation is made. 相似文献
994.
A discrete time nonlinear filter is used to estimate the volatility in a financial model. New filters are derived for sums of unobserved quantities and the EM algorithm applied to determine the parameters of the model. 相似文献
995.
For a class of time-varying nonlinear systems described by the equation
, the precalculating control is not available if the input matrixg(x,t) is not invertible. With Lyapunov's second method, a stabilizing controller which makes the system practically stable is constructed in this paper. It is shown that the implementation of this scheme depends on some so-called posi-invertibility conditions forg(x,t). In case the system is partly stable, the method, named part-calculating control, can simplify the on-line computations. Without the assumption that the nominal system is asymptotically stable, the method is applied to the problems of control for the corresponding uncertain system that satisfies the matching condition. When the matching condition is not satisfied, the mismatching control problem is also studied with Lyapunov's second method.This work was supported by the Science Fund of the Chinese Academy of Science. 相似文献
996.
T. Carletti D. Fanelli A. Guarino F. Bagnoli A. Guazzini 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,64(2):285-292
We here discuss the process of opinion formation in an open community where agents are made to interact and consequently update
their beliefs. New actors (birth) are assumed to replace individuals that abandon the community (deaths). This dynamics is
simulated in the framework of a simplified model that accounts for mutual affinity between agents. A rich phenomenology is
presented and discussed with reference to the original (closed group) setting. Numerical findings are supported by analytical
calculations. 相似文献
997.
L. Krlín R. Paprok V. Svoboda 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(1):95-109
We model and discuss the possible types of motion that charged particles may
undergo in a stationary and spatially periodic electrostatic potential and a
homogeneous magnetic field. The model is considered to be the simplest
approximation of more complex phenomena of plasma edge turbulence in
tokamaks. Therein, low frequency turbulence appears in the plasma edge,
resulting in a fluctuation of the electron density, and also in the
generation of a turbulent electrostatic field. Typical parameters of this
turbulent electrostatic field are an electrical potential amplitude of
10–100 V and wave numbers k≈103 m-1. In our model, we consider these regimes, together
with a homogeneous magnetic field with a magnitude of 1 T. We investigate the
dynamics of singly-ionized carbon ions – a typical plasma impurity – with
kinetic energies on the order of 10 eV. Besides the obvious
Larmor and drift motions, a motion of random-walk and of Lévy walk
character appear therein.
All of these types of motion can play an important role in the modelling of
the anomalous diffusion of particles from the plasma edge turbulence region.
The dynamics mentioned will cause an inevitable escape of energetic
particles and thus of power loss from the thermonuclear reactor.
Moreover, Lévy walk kinetics represents a very interesting kind of
kinetics, currently of great interest, which was previously not so often
discussed. 相似文献
998.
C. X. Zhang B. Zhou Y. H. Nie J. Q. Liang J. Liu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(2):161-165
We study the transport of atoms across a localized Bose-Einstein condensate in an onedimensional optical lattice with a single
defect. Our analytical and numerical results show that the defect as well as the nonlinear parameter can control the transmission
of the atoms beam and the position of total reflection caused by Fano resonance. These interesting features may be a very
useful basis for devising tunable atom filters or a button. 相似文献
999.
J. -B. Liu X. -Y. Lü N. Liu P. Huang C. -L. Ding J. Li 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(4):479-484
Using the Schrödinger-Maxwell equations, we theoretically investigate the propagation properties of a transverse acoustic wave in a crystal of molecular magnets in the presence of two strong ac resonant magnetic fields and a weak acoustic wave. The acoustic wave can freely propagate in the magnetic molecule medium (under appropriate conditions) due to quantum interference. Furthermore, using the slowly varying envelope approximation, we discuss the propagation equation of the acoustic wave, which includes the high order nonlinear term. The results show that a crystal of molecular magnets can support the propagation of acoustic wave solitons via electromagnetically induced transparency. We also obtain the analytical expressions for the phase shift and absorption coefficient of the acoustic wave within certain parameters. 相似文献
1000.
N. Kouvaris A. Provata 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,66(1):97-106
An ecosystem containing three interacting species is studied using both Mean Field approach and Kinetic Monte Carlo
simulations on a lattice substrate. The so called 3rd order LLV model involves birth, death and reaction
processes with 3rd order nonlinearities and feedbacks. At the mean field level this system exhibits conservative
oscillations; the analytic form of the constant of motion is presented. The stochastic simulations show that the
density oscillations disappear for sufficiently large lattices, while they are present locally, on small lattice
windows. Introduction of mixing via long range migration in the two reacting species changes this picture. For small
migration rates p, the behavior remains as with p = 0 and the system is divided into local asynchronous oscillators.
As p increases the system passes through a phase transition and exhibits a weak disorder limit cycle through a supercritical
Hopf-like bifurcation. The amplitude of the limit cycle depends on the rate p, on the range of migration
r and on the system kinetic rates k1, k2 and k3. 相似文献