No abstract

No abstract

A combined finite element and analytical method is presented here for analyzing scattering of time harmonic horizontally polarized shear (SH) waves by material and geometric irregularities in an isotropic linearly elastic infinite plate. All the irregularities are assumed to be contained in a bounded region. The problem of scattering is solved by replacing this region with a finite element mesh. A nodal force-displacement relation is developed to satisfy the continuity conditions along the boundaries separating the inner finite-element region from the exterior regular region. The method is illustrated by solving the problem of scattering of SH waves by a surface breaking crack. The crack is taken to be normal to the surface of the plate. The reflection and transmission coefficients are computed for zeroth, first, and second incident wave modes. The validity and accuracy of the results are checked by satisfaction of the energy conservation principle and the reciprocity relations.

#DUVTCEV In this paper we consider the application of stochastic optimal control theory to the design of an active vehicle suspension with preview control. An integral constraint is included in the performance index to achieve better attitude control characteristics. The two-degree-of-freedom vehicle model travels with constant velocity on both random and deterministic roadways. Information relating to roadway disturbances about to be encountered by the moving vehicle is assumed to be sensed and this information is used by the active control scheme to prepare the system for the ensuing input. We examine the effect of preview control on vehicle performance characteristics in terms of ride comfort, suspension deflection, road-holding ability, control force, and power requirements. The performance characteristics of the devised multivariable controller are evaluated and compared with those of the pertinent active suspension systems based on state variable feedback and conventional passive systems.-G[ 9QTFU Active suspension, preview control, integral constraint AB@8A6?4GHE8

No abstract