Abstract: Automatic detection of the activities of a user of a data processing system is provided by the use of an Activity Event Detection Process, an Activity Detection Process, and an Interrogator Process. The Activity Event Detection Process detects events indicating user activity. The Activity Detection Process evaluates the user activity indicating events to determine the activity of a user. The Interrogator Process provides an interface to a requesting user and formulates appropriate queries to be sent to one or more Activity Detection Processes.

Abstract: A retrievable bridge plug apparatus has slip segments and packing elements which are extendable to outward positions. In a cased well, the slip segments grip the casing and prevent the longitudinal movement of the bridge plug. The packing elements contact the casing to provide a seal to isolate the well interval above the bridge plug from the well interval below the bridge plug. The bridge plug is retrieved from the well by equalizing pressure and then retracting the slip segments and packing elements. Pressure is equalized by pulling up on the retrieving tool, which couples to a fishing neck at the upper end of the bridge plug. Pulling up on the fishing neck opens a valve and exposes a flow path for fluid. The slip segments, and consequently the packing elements, are prevented from retracting during the equalization of pressure by a locking device. Then, the retrieving tool is set down to lower the fishing neck. Lowering the fishing neck releases the locking device.

Abstract: A shaped charge has provision for bleeding off internal pressure. The shaped charge has a case, a cap, and an O-ring. The case and the cap each have a first end. The case and the cap are assembled together by one of the first ends receiving the other first end. A groove is formed between the case and the cap; the groove receives the O-ring. The groove is provided with a gap on the external pressure side of the O-ring. The gap communicates with the exterior of the shaped charge. When internal pressure is greater than external pressure, the O-ring is deformd and extrudes into the gap, thereby exposing the gap to the internal pressure and allowing the internal pressure to vent out of the shaped charge. The gap is formed either by beveling an edge of the groove or by a borehole extending from a position that communicates with the exterior of the shaped charge to an opening in the groove.

Abstract: A solenoid has a coil with an outer core and an inner core. The cores provide the magnetic circuit around the coil. The inner core includes a rotor which has radially extending armatures. The armatures are positioned in gaps between radially extending poles of the outer core so as to form air gaps between the poles and the armatures. When the coil is energized, the armatures are attracted to the poles and cause the rotor to rotate, thereby closing the air gaps. The shaft is coupled to the rotor through a drive mechanism so as to rotate with the rotor. The shaft is made of a material with a relatively high magnetic permeability, as are the inner and outer cores, so that the shaft is magnetically coupled to the inner core rotor. When the rotor stops rotating, the shaft also stops. A return spring returns the rotor to its deenergized position when the coil is deenergized, recreating the air gaps. The drive mechanism allows the shaft to remain stationary while the rotors return to the deenergized position.

Abstract: A fluorescent lighting installation incorporates a first switch device for applying and removing power from the installation and a plurality of second switch devices for providing plurality light levels. The respective second switch devices are located within respective ones of a plurality of selected fluorescent lighting fixtures and are interconnected with the respective power inputs, fluorescent lamps and ballasts of the respective selected fluorescent lighting fixtures. The respective second switch devices are operable to step through plural states to provide plural operating states for the fluorescent lamps in the selected fluorescent lighting fixtures. The second switch devices step from one state to the next in response to the application of power for an indefinite period of time by the first switch device.