The paper deals with the interaction between buckling and resonance instabilities of mechanical systems. Taking into account the effect of geometric nonlinearity in the equations of motion through the geometric stiffness matrix, the problem is reduced to a generalized eigenproblem where both the loading multiplier and the natural frequency of the system are unknown. According to this approach, ...

The present study is devoted to an approximate modeling for numerical simulation of flows past oscillating airfoils. In this study, it is shown that the harmonic oscillating objects can be studied by simple numerical codes that are not able to solve moving grids. Instead of using moving grid for the simulation of flowfield around an oscillating airfoil, this unsteady flow is solved on a fixed g...

In a set of experiments, Couder et al. demonstrate that an oscillating fluid bed may propagate a bouncing droplet through the guidance of the surface waves. I present a dynamical systems model, in the form of an iterative map, for a droplet on an oscillating bath. I examine the droplet bifurcation from bouncing to walking, and prescribe general requirements for the surface wave to support stabl...

A new method for the calculation of the spectral line broadening in plasma has been developed and implemented. The main idea of the method is to numerically simulate the motion of the plasma particles, both ions and electrons, and use the resulting time-dependent field to evaluate the emitter oscillating function, the Fourier transform of which provides the spectral line shape. We applied this ...

Kinematics and the dynamics analysis of a two-wheeled mobile robot comprising an oscillating intermediate central body are established in the paper. The dynamics of this mechanical system is formulated using the fundamental principle of virtual work, but it has been verified the results in the framework of the Lagrange formalism with their multipliers. The study of the dynamics problems of the ...

Using both a recent calculation by Bruch of the damping of the motion of a monolayer nitrogen film oscillating harmonically on a metallic surface due to Ohm's law heating and a Thomas-Fermi approximation treatment of the Ohm's law heating mechanism, which accounts for the nonzero thickness of the surface region of a metal, it is argued that this mechanism for friction is able to account for rec...

A high order spectral difference (SD) scheme based cost-effective multi-level optimization approach is proposed to optimize the kinematics of flapping airfoils and provide further insights into flapping motions with maximum propulsive efficiency. At the first stage, a gradient-based optimization algorithm is coupled with a second-order SD Navier-Stokes solver to search for the optimal kinematic...

We summarize unusual bound or localized states in quantum mechanics. Our guide through these intriguing phenomena is the classical physics of the upside–down pendulum, taking advantage of the analogy between the corresponding Newton’s equation of motion and the time independent Schrödinger equation. We discuss the zero–energy ground state in a three–dimensional, spatially oscillating, potential...

We observe parametric amplification in a torsional micron-scale mechanical resonator. An applied voltage is used to make a dynamic change to the torsional spring constant. Oscillating the spring constant at twice the resonant frequency results in a phase dependent amplification of the resonant motion. Our results agree well with the theory of parametric amplification. By taking swept frequency ...