The fluid dynamics of many swimming and flying animals involves the generation and shedding of vortices into the wake. Here we studied the dynamics of similar vortices shed by a simple two-dimensional flapping foil in a soap-film tunnel. The flapping foil models an animal wing, fin or tail in forward locomotion. The vortical flow induced by the foil is correlated to (the resulting) thickness va...

We carried out a systematic study on the effect of nanocrystalline TiO2 paste formulations and temperature treatment on the performance of dye solar cells (DSCs) over a large temperature range, to provide useful information for the fabrication of both plastic and metal flexible devices. We compared conventional screen-printable and binder-free TiO2 pastes with a new formulation which includes h...

‘THEUSE of heavy aluminum foil in our ashing procedure for PB1 (1), introduced 3 years ago, has proved extremely successful in preventing cross-contamination. A Temco double-door muffle furnace is used for which three steel buckets were made; small buckets, 4 in. wide, 6 in. long, and 6 in. deep, and one large bucket, 6 in. wide, 8 in. long, and 6 in. deep. A steel shovel was made to aid the te...

Nanocrystalline fluorinated silicon films are studied by using Raman spectroscopy, electron paramagnetic resonance, Fourier-transformed infrared spectroscopy, atomic force microscopy, nonlinear laser spectroscopy, and photoluminescence. Electrical properties of nanocrystalline silicon and amorphous silicon films were compared. The field-assisted migration of point defects is dramatic for durabi...

In an earlier paper, [5], I gave semantics and tableau rules for a simple first-order intensional logic called FOIL, in which both objects and intensions are explicitly present and can be quantified over. Intensions, being non-rigid, are represented in FOIL as (partial) functions from states to objects. Scoping machinery, predicate abstraction, is present to disambiguate sentences like that ass...

Nanocrystalline materials have experienced a great deal of attention in recent years, largely due to their impressive array of physical properties. In particular, nanocrystalline mechanical behavior has been of interest, as incredible strengths are predicted when grain size is reduced to the nanometer range. The vast majority of research to this point has focused on quantifying and understandin...

Several different working principles exist to drive a valveless pump. An efficient pump may be designed by placing a flapping foil into a channel filled with fluid. In the case of inviscid flow, the pressure difference along the channel is equivalent to the thrust force acting on the propulsor. The focus in this talk is to find foil movements of highest propulsive efficiency for a given thrust....

Vortex control is a new paradigm in fluid mechanics, with applications to propulsion and wake reduction. A heaving and pitching hydrofoil placed in a flow with an array of oncoming vortices can achieve a very high propulsive efficiency and reduced wake signature. The canonical example of flow with regular arrays of vortices is the Krman vortex street, and this is our model for the inflow to the...

This thesis investigates the hydrodynamic effects of biologically-inspired leading-edge tubercles. Two complementary studies examine the performance of three-dimensional hydrofoils based on the pectoral flippers of the Humpback Whale (novangilae megaptera). The first study uses a static foil, with application to conventional control surfaces– such as rudders or dive planes–found on marine vehic...

A two-dimensional nonlinear inverse fluid-structure interaction problem for a curvilinear elastic hydrofoil is considered. A cavity formed behind the foil is modeled according to the single-spiral-vortex model by Tulin. The fluid-structure problem is decoupled by the method of successive approximations. For the cavitation problem, the foil is modeled as a polygon. The method of conformal mappin...