This paper presents a method for estimating Coulomb and viscous friction coefficients from responses of a harmonically excited dual-damped oscillator with linear stiffness. The identification method is based on existing analytical solutions of non-sticking responses excited near resonance. The method is applicable if the damping ratio of viscous component can be considered small. The Coulomb an...

An enhancement of vortex-motion damping in thin Pb/In superconducting films is obtained through coupling to an adjacent two-dimensional electron gas formed in a modulation-doped GaAs/AlGaAs heterostructure. This effect is observed by monitoring the power dissipation in the superconductor in the vortex state while increasing the density of the electron gas using a gate voltage. Quantitative agre...

Abstract Undesired oscillations often emerge in numerical solutions, especially the case of dynamic problems. These are mainly spurious which must be eliminated or reduced at least to provide accurate results. Numerical methods with damping effect useful achieve this goal. However, concrete shape characteristics has a great impact on effectiveness. Dissipative mostly have specific character ver...

We present results for stiffness and damping prediction in a class of layered, wavy, metal–polymer composites that exceed conventionally published stiffness-damping maps (The Wang–Lakes line, see [14]). These composites are realized by judiciously placing selected, wavy, metal sheets that sandwich an ultra-thin layer of polymer. Stacks of alternating metal–polymer layered composites, when compr...

A mathematical model is described to investigate the damping moment of weakly nonlinear roll and yaw motions of a floating body in time domain under the action of sinusoidal waves. The mathematical formulation for added mass moment of inertia and damping is presented by approximating time-dependent coefficients and forcing moments when small distortion holds. Using perturbation technique, we ob...

The modeling of damping is very complex and still considered somewhat an unknown or grey area. Recently, model updating methods has been used to update the damping matrix based on measured dynamic test data to accurately represent energy dissipation mechanism in dynamic systems. Most of the finite element updating methods considers that the dynamic systems are viscous and proportional. In this ...

We determine the linear viscoelastic response of jammed packings of athermal repulsive viscous spheres, a model for emulsions, wet foams, and soft colloidal suspensions. We numerically measure the complex shear modulus, a fundamental characterization of the response, and demonstrate that low frequency response displays dynamic critical scaling near unjamming. Viscoelastic shear response is gove...

The global viscous damping rate in MST has been studied experimentally[1]. In these experiments a biased electrode was applied to a steady RFP plasma with Θ ∼ 1.8. This causes a radial electric field Er, which in turn induces an increased toroidal velocity in the discharge that reaches a steady value. When the electrode is removed, the toroidal flow is damped with a characteristic time τsd ∼ 0....

The evolution of modulational instability, or Benjamin-Feir instability is investigated within the framework of the two-dimensional fully nonlinear potential equations, modified to include wind forcing and viscous dissipation. The wind model corresponds to the Miles’ theory. The introduction of dissipation in the equations is briefly discussed. Evolution of this instability in the presence of d...

We investigate the damping of neutron star r-modes due to the presence of a viscous boundary (Ekman) layer at the interface between the crust and the core. Our study is motivated by the possibility that the gravitational-wave driven instability of the inertial r-modes may become active in rapidly spinning neutron stars, eg. in low-mass X-ray binaries, and the fact that a viscous Ekman layer at ...