Abstract: A three dimensional structure, including but not limited to a playhouse for children, includes at least three interlocking panels that are configured so as to interlock one with at least one other without the use of hand tools. The at least three interlocking panels have an interior surface and an exterior surface, where at least one of the interior surface and the exterior surface of one or more of the at least three interlocking panels has a first printed pattern applied thereon. Also disclosed are methods of manufacturing and selling the three dimensional structure.

Abstract: A technique for obtaining a class of beam patterns is described which results in eliminating the Doppler spread effect of the mean transverse component of flow of scatterers. This is accomplished by weighting various array elements. This component of flow is typically the main contributor to Doppler frequency spread. With this component eliminated, the other contributor of Doppler spread is due to the turbulent or fluctuating scatterer motion on the scale of the scattering volume. This contributor is smaller of the two and is estimated by standard Doppler methods.