Wave motion in acoustic and elastic media is highly influenced by the presence of outer boundaries and media interfaces. The solutions to the equations governing the wave motion at any point in the domain as a function of time can be sought either through analytical or numerical techniques. This thesis proposes provably stable finite difference schemes to accurately simulate wave interaction wi...

A stability criterion for universal fuzzy position control drives is described. This method allows an immediate definition of the stability boundaries through the knowledge of common motor parameters. The method can be applied to almost every type of motors, from DC to Synchronous, regardless of most fuzzy controller characteristics. “Elastic” fuzzy controller "gain" limits can be established a...

We present an Immersed Boundary method for interactions between elastic boundaries and mixtures of two fluids. Each fluid has its own velocity field and volume-fraction. A penalty method is used to enforce the condition that both fluids' velocities agree with that of the elastic boundaries. The method is applied to several problems: Taylor's swimming sheet problem for a mixture of two viscous f...

Nematic elastomers exhibit a rich elastic response to external stresses. Of particular interest is the semisoft response of elastomers with an anisotropy direction (z) frozen in by a double cross-linking process. This response is characterized by a stress-strain curve for stresses along x perpendicular to z that rises initially, exhibits a nearly flat plateau between two critical values of stra...

The dynamics of dislocation assemblies in deforming crystals indicates the emergence of collective phenomena, intermittent fluctuations and strain avalanches. In polycrystalline materials, the understanding of plastic deformation mechanisms depends on grasping the role of grain boundaries on dislocation motion. Here the interaction of dislocations and elastic, lowangle grain boundaries is studi...

By including acoustic-elastic interactions in a topology optimization based on the covariance matrix adaptation evolution strategy, we developed acoustic cloaks of optimal design that render an object unobservable through airborne and water-borne sounds. This strategy helps exploring topologies minimize scattering sounds around made from acrylonitrile butadiene styrene copolymers frequently use...