Abstract: A solar radiation collector system includes a curved rim, a collector assembly including a plurality of solar radiation transducer elements passing through the plane of and connected to the curved rim, and a plurality of relatively small diameter tension members connected in distributed manner between the curved rim and the collector assembly and forming a stiff, lightweight, bicycle wheel-type tension-compression support structure. The support structure is rotatably supported from the ground in a manner to allow for three dimensionally stable support and rotation of at least ninety degrees with respect to the ground. Rotation of the bicycle wheel-type tension-compression support structure provides for a desired primary tracking motion to adjust for the apparent motion of the sun, and movement of the transducer elements provides for a second dimension adjustment for the apparent motion of the sun.

Abstract: A differential hoist and drive includes a differential escapement mechanism arranged mechanically between and in combination with a pair of direction turning members, such as pulleys. An endless loop of a flexible force transmitting element (cable, chain, strap, or the like) interconnects the direction turning members and the differential escapement. The load can be connected to either the differential escapement or the direction turning members with the other being anchored as a fixed member. The load is restrained from swinging or from other unintended movement. A turnbuckle or other suitable device provides for a desired pretensioning of the loop of flexible force transmitting element.

Abstract: A demand defrost controller employs temperature measurements taken at the outlet of the discharge air curtain and the inlet of the air return to determine the need for defrost. If the difference between these temperature measurements exceeds a set point for a predetermined sustained period of time and a minimum amount of time has elapsed since the last defrost of the case, defrost is initiated. Regardless of the value of the temperature difference, defrost is initiated if elapsed time since the last defrost exceeds a specified maximum time between defrosts for the case. Defrost can be terminated on the basis of time and/or temperature. The demand defrost controller can also control display case temperature and can be applied to independently control multiple display case circuits.

Abstract: A normally flat, rectangular mirror element is supported on the front surface of a normally flat, rectangular backing element, which is more rigid than the mirror element. A pair of spacer elements are positioned between the mirror element and the backing element to raise the mirror element above the backing element. The spacer elements are located adjacent one pair of parallel edges of the mirror element. To curve the mirror about a central longitudinal bending axis which is parallel to the spacer elements, the mirror is depressed at its center, along the longitudinal axis, and secured to the backing element by a strip of double sided adhesive tape, which maintains the mirror element in the depressed position.