Abstract: A method for conducting a computerized simulation of a collision between at least two objects. The method includes creating a representation of each of the objects. Each representation is typically is a mesh of nodes and surface elements. The method also typically includes colliding the representations of the objects such that the representations contact each other, and at least a first representation experiences a respective deformation at each of a plurality of contact points. In addition the method typically includes, for at least a subset of the plurality of contact points, computing a respective local collision force associated with the deformation at such contact points, and calculating a resultant generalized collision force acting at a predetermined point associated with the first representation based on the local collision forces. Typically, the respective local collision force is related to a distance the region of the representation is deformed by a deformation relationship.

Abstract: An improved eddy current braking system for fly wheel braked exercise equipment includes the use of a flat aluminum disc and electromagnets to either side of the disc adjacent to the periphery thereof, with the electromagnets containing multiple pole pieces to multiply the torque so as to reduce heating and power consumption. The utilization of aluminum achieves a flat torque versus speed characteristic vis-a-vis copper discs over the normal operating speed range. Additionally, the utilization of aluminum prevents the warpage associated with copper.

Abstract: An electromechanical and more particularly an electromagnetic brake is utilized in the control of exercise equipment including escalator type stair-climbing apparatus, in which electronically controllable torque, including a clamping torque, is applied to a rotary shaft to load the exercise equipment, thereby giving complete electronic control to the operation of the exercise apparatus including a safety locking function.

Abstract: A collimator suitable for use in the creation of more than one miniaturized image of a radioactive concentration simultaneously by a radiation receiving and imaging device, said collimator having at least two adjacent collimating sections separated by areas substantially opaque to radiation from the radioactive object, each such collimating section being a grid-like arrangement of wall portions, adapted to absorb substantially all radiation from the radioactive object which impinges thereon, extending between the top surface and the bottom surface of the collimator defining a plurality of holes therebetween of substantially any desired cross-sectional shape.

Abstract: A collimator for radiation receiving and imaging devices and a method for making such collimators including the steps of forming a plurality of modular elements each comprising a foil sheet bent so as to form a plurality of elongated ridges on both sides thereof so as to form elongated channels therebetween, partially inserting the ridges of one module into the channels on the adjacent side of the succeeding module in a modified mortis-tenon relationship successively and affixing them in that position, placing the assembled grid into a frame, and filling the spaces between the grid and the frame with radiation-opaque material, thereby forming an integral functional collimating unit.

Abstract: A collimator for radiation receiving and imaging devices and a method for making such collimators including the steps of casting a plurality of modular elements each having a base from one side of which extends a first plurality of spaced columns and from the opposite side of which extends a second plurality of columns of shorter height than the first directly opposite the spaces between the first plurality of columns, inserting the first plurality of columns of one module into the spaces between the second pluraity of columns of the succeeding module in a modified mortis-tenon relationship successively and affixing them in that position, placing the assembled grid into a frame, and filling the spaces between the grid and the frame with radiation-opaque material, thereby forming an integral functional collimating unit.