Hierarchical data structures have been widely used to design e cient algorithms for interference detection for robot motion planning and physically-based modeling applications. Most of the hierarchies involve use of bounding volumes which enclose the underlying geometry. These bounding volumes are used to test for interference or compute distance bounds between the underlying geometry. The e ci...

Electrically small oblate spheroidal and spherical antennas in confocal shells with negative permittivity represent perspective antenna design to combine moderately small size, wide bandwidth, high efficiency and power of radiation. However, optimization of the antennas performance parameters imposes contradictory restrictions on permittivity of the shells, electrical size of the antennas, shap...

Cylindrical shells under uniaxial compression and spherical shells under equi-biaxial compression display the most extreme buckling sensitivity to imperfections. In engineering practice, the reduction of load carrying capacity due to imperfections is usually addressed by use of a knockdown factor to lower the critical buckling stress estimated or computed without accounting for imperfections. F...

Fullerene molecules such as C(60) are large nearly spherical shells of carbon atoms. Pairs of such molecules have a strong long-range van der Waals attraction that can produce scattering or binding into molecular crystals. A simplified classical-electrodynamics model for a fullerene is a spherical metal shell, with uniform electron density confined between outer and inner radii (just as a simpl...

The gauge usually adopted for extracting the reduced Hamiltonian of a thin spherical shell of matter in general relativity, becomes singular when dealing with two or more intersecting shells. We introduce here a more general class of gauges which is apt for dealing with intersecting shells. As an application we give the hamiltonian treatment of two intersecting shells, both massive and massless...

We report a new structure, mesoporous structured polyhedral drum and spherical cages and shells formed by textured self-assembly of ZnO nanocrystals, which are made by a novel self-assembly process during epitaxial surface oxidation. The cages/shells exhibit unique geometrical shapes, and their walls are composed of mesoporous and textured ZnO nanocrystals. The structures of the cages and shell...