The development and applications of a supplemental viscous damping device with active capacity are described. The system of the dampers de ned as active viscous damping system (AVDS) is presented herein. Structural control principles de ned here as active control theory (ACT) are used to obtain the control forces at each time step during an excitation. Control of the damping forces is possible ...

We consider a mechanical system excited by an external force. Model of such a system is described by the system of ordinary differential equations: Mẍ(t) + D(v)ẋ(t) + Kx(t) = f̂(t), where matrices M,K (mass and stiffness) are positive definite and the vector f̂ corresponds to an external force. The damping matrix D(v) is a positive semidefinite matrix which depends on damping positions and parame...

A physically-based computational model is developed to predict the damping behavior of oxide thermal barrier coating systems. The constitutive damping model is derived from the theory of point defect relaxation in crystalline solids and implemented within a finite element framework. While oxide coatings have been primarily employed as thermal barriers for gas turbine blades, there is a growing ...

We seek numerical methods for second-order stochastic differential equations that reproduce the stationary density accurately for all values of damping. A complete analysis is possible for scalar linear second-order equations (damped harmonic oscillators with additive noise), where the statistics are Gaussian and can be calculated exactly in the continuous-time and discrete-time cases. A matrix...

A state of the art numerical tool has been developed to simulate the QsTj propagation and the absorption of coexisting diffemt types of waves in a tokamak geometxy. The code includes a numerical solution of the three-dimensional (R, Z, 0) toroidal wave equation for the electric field of the different waves in the WKBJ approximation. At each step of integration, the two-dimensional (VI!, v~ Fokk...

The damping vibration characteristics of magneto-electro-viscoelastic (MEV) nanobeam resting on viscoelastic foundation based on nonlocal strain gradient elasticity theory (NSGT) is studied in this article. For this purpose, by considering the effects of Winkler-Pasternak, the viscoelastic medium consists of linear and viscous layers. with respect to the displacement field in accordance with th...

A numerical technique, composed of the Van Leer-Tai-Powell optimization and a modified procedure, is applied to design multistage schemes that give optimal damping of high frequencies for given upwind-biased spatial differencing with implicit and explicit residual smoothing. The analysis is done for a scalar convection equation in one space dimension. The object of this technique is to make the...

We consider a linear damped wave equation defined on a two-dimensional domain Ω, with a dissipative term localized in a subset ω. We address the shape design problem which consists in optimizing the shape of ω in order to minimize the energy of the system at a given time T . By introducing an adjoint problem, we first obtain explicitly the (shape) derivative of the energy at time T with respect...