Andrew F Mitchell

US Patent:

42627443, Apr 21, 1981

Filed:

Dec 14, 1979

Appl. No.:

6/103932

Inventors:

Andrew Mitchell - Pompano Beach FL
Kermit W. Janssen - Valley Forge PA

Assignee:

Certain-teed Corporation - Valley Forge PA

International Classification:

B01D 2910
E03B 320
E21B 4308

US Classification:

166227

Abstract:

A well screen and method for its manufacture are disclosed. The well screen is assembled from molded parts. The parts are initially formed with a continuous, imperforate outer skin. Continuous circumferential slots are cut in the skin to form a foraminous screen. Integrally formed annular ribs located between each slot provide crush resistance.

US Patent:

61236470, Sep 26, 2000

Filed:

Sep 17, 1998

Appl. No.:

9/142926

Inventors:

Andrew John Mitchell - Chicago IL

International Classification:

A63B 2202

US Classification:

482 54

Abstract:

An omni-directional treadmill providing a surface with no gaps on which a user can move. The treadmill is generated by arranging a set of looped belts (1, 2, 10), each providing at least one elongated surface, abutting one another along the elongate edges provided by the elongate surface. A group of these elongate surfaces defines the treadmill surface. This set of belts (1, 2, 10) is itself arranged in a loop. Movement of the whole set of belts around this loop moves the treadmill surface in one direction. Simultaneous rotation of all the belts (1, 2, 10) providing the surface provides movement perpendicular to the first direction. Using these two components of motion the treadmill can move in any direction indefinetly. Feedback from user can be used to move the treadmill in the opposite direction to keep user in the same place, in the same way a treadmill maintains user moving in one direction in the same place.