Abstract: A mixing assembly includes a drum including a side wall, a top portion, and a bottom portion, in which the top portion includes a first opening for filling a substance into the drum, a second opening for mixing the substance in the drum, and a third opening for extracting the substance from the drum; and a mixer releasably disposed in the drum, including a head releasably attached to the second opening for mixing, in which the head includes a housing including an internal hollow region extending along the central axis of the head, and external threads configured to be attached to the second opening for mixing by thread engagement, a shaft disposed in the hollow region, and an impeller assembly disposed at a bottom end of the shaft for stirring the substance in the drum.

Abstract: A beam forming system includes one or more beam forming elements that are arranged to provide a non-planar doubly ruled radiation surface. The surface is defined by two families of rulings such that the length of the rulings within each family are configured to provide a radiation surface with substantially straight boundary edges, and the beam forming system is arranged to form acoustic beams.

Abstract: A beam forming system (10) for acoustic or electromagnetic beams comprising one or more beam forming elements (2) that are arranged to provide a doubly ruled radiation surface.

Abstract: A composite antenna for hand held communications applications comprising at least two individual antennas spaced from each other at less than 0.3 wavelengths relative to the frequency to be received. Preferably the individual antennas are arranged in two or more arrays each of 2, 3, 4, 5 or more individual closely spaced antennas. Preferably each of the individual antennas is between 0.1 and 0.7 wavelengths long and most preferably about 1/4 wavelengths long. The composite antenna may be designed to operate in the 800 MHz to 5 GHz range. Preferably the individual antennas are spaced from each other in the direction of orientation of the individual antennas to assist in each individual antenna receiving a signal as uncorrelated as possible to the signal received by the other individual antennas of the composite array.