Abstract: Fluidic devices, including blind vortex tubes, constant-rotation double diodes and constant-rotation double vortex tubes, are disclosed with which to construct pulse tube refrigerators, including ones having diode loops, constant-rotation double diodes, constant-rotation double vortex tubes, and asymmetrical diode stacks. Present orifice pulse tube refrigerators use an orifice connected at the warm end of the pulse tube to a reservoir. The orifice and reservoir serve to control flows at the warm end of the pulse tube so that they are not in phase with flows at the cold end. Present heat exchangers at the warm end suffer inefficiencies due to heat-regenerative effects caused by return flows through the orifice. The fluidic devices disclosed herein create dynamic replacement orifices for pulse tube refrigerators that also serve as efficient heat exchangers and supercoolers with minimal regenerative characteristics.

Abstract: An air amplifier is provided for use in pneumatic control systems that can operate over a wide range of flow and pressure characteristics, and can additionally operate against a back pressure. The air amplifier utilizes a tapered shim that causes the pressurized air to follow a Coanda profile over a wider range (and against a back pressure) than is possible when using only a slotted, non-tapered shim. The shim is ring-shaped with a planar surface and includes inwardly directed tangs that are cut-off to provide an open central area. Some or all of the tangs are tapered along either one or both sides of the tang.

Abstract: A sofa bed convertible from a sofa to a bed having a self-supporting stationary section, a first movable section slidably attached to the stationary section, and a second movable section slidably attached to the first movable section. Independently supported spaced arms are removably attached to the sides of the stationary section to serve as arm supports for persons seated on the sofa bed, but not as structural supports for the stationary section. A hollow furniture-type back is removably connected between the arms. A hinged mattress overlies the stationary and movable sections when the sofa bed is being utilized as a bed. The rearmost portion of the mattress may be doubled over so that the resulting double-thickness section may slide rearwardly and upwardly into the hollow back for storage, with the forward part of the mattress forming a resilient seating surface when the sofa bed is being utilized as a sofa.