Scale Effects on Oscillatory Control-Surfeoe Derivatives-By-A. Y/. Moore Aerod.ynsmlcs Division NPL The limited evidence availahle concerning scale effects on Control-surface derivatives suggests a general tendency for in-phase hinge-moment derivatives to increase when Reynolds number increases but to decrease sharply when boundary-layer transition is artificially fixed. Damping (in-quadrature)...

In this paper, we present a rapid boundary stabilization of Timoshenko beam with anti-damping and anti-stiffness at the uncontrolled boundary, by using PDE backstepping. We introduce transformation to map states into (2+2) × hyperbolic PIDE-ODE system. Then backstepping is applied obtain control law guaranteeing closed-loop stability origin in H1 sense. Arbitrarily can be achieved adjusting par...

In this paper, we design interconnected hierarchical rank-structured methods for the fast direct solution and effective preconditioning of the Helmholtz equation. First, for essentially elliptic PDEs, a direct method is proposed to exploit interconnected structures within two hierarchical layers: the hierarchical partitioning of a large problem into sub-problems for smaller subdomains, and the ...

Abstract In the present work, we establish a blow-up criterion for viscoelastic wave equations with nonlinear damping, logarithmic source, delay in velocity, and acoustic boundary conditions. Due to damping term, cannot apply concavity method introduced by Levine. Thus, use energy show that solution negative initial blows up after finite time. Furthermore, investigate upper lower bounds of

considerations on the explosion resistant design of special infrastructures have increased in the recent years. amongst the various types of infrastructures, road and railway tunnels have a unique importance due to their vital role in connection routes in emergency conditions. in this study, the explosion effects of a projectile impacting on a railway tunnel located in a jointed rock medium has...

The presence of a viscous boundary layer under the solid crust of a neutron star dramatically increases the viscous damping rate of the fluid r-modes. We improve previous estimates of this damping rate by including the effect of the Coriolis force on the boundary-layer eigenfunction and by using more realistic neutron-star models. If the crust is assumed to be perfectly rigid, the gravitational...

Malaysians were reported to have the most number of Facebook friends, spend more time on Facebook and might be addicted to Facebook as well. This paper explored Facebook usage pattern, motivations and psycho logical/behavioural factors affecting the users. A focus group study was first conducted to explo re motives to use Facebook and symptoms related to excessive Facebook usage. The themes eme...

This paper deals with local existence of strong solutions for semilinear wave equations with power-like interior damping and source terms. A long standing restriction on the range of exponents for the two nonlinearities governs the literature on wellposedness of weak solutions of finite energy. We show that this restriction may be eliminated for the existence of higher regularity solutions by e...

We consider the problem of boundary stabilization of a 1-D (one-dimensional) wave equation with an internal spatially varying antidamping term. This term puts all the eigenvalues of the open-loop system in the right half of the complex plane. We design a feedback law based on the backstepping method and prove exponential stability of the closed-loop system with a desired decay rate. For plants ...

We consider a boundary value problem generated by Sturm-Liouville equations on the edges of a star-shaped graph. Thereby a continuity condition and a condition depending on the spectral parameter is imposed at the interior vertex, corresponding to the case of damping in the problem of small transversal vibrations of a star graph of smooth inhomogeneous strings. At the pendant vertices Dirichlet...