Abstract: A computer implemented method of defining an object union in an object oriented programming environment, comprising the steps of: selecting a first class from which a first object to be contained in the object union will be instantiated at runtime; selecting a second class from which a second object to be contained in the object union will be instantiated at runtime; selecting a policy function for operating on the first and second classes, at runtime, in order to define which methods supported by the first and second classes will be accessible via the object union at runtime.

Abstract: A desktop manager for a multi-processing graphic user interface operating system operates to control the display of a plurality of controls each occupying respective display areas on a desktop. An improved desktop manager characterised by means adapted to receive a request for urgency from a process owning a control; and means adapted to diminish the display of one or more of any other controls to draw the attention of a user to the control owned by the process requesting urgency is disclosed.

Abstract: A file system for a computer supports a plurality of directories, each maintaining a list of data files as a plurality of directory entries. As well as means for creating data entries for real data files, the system includes means for creating anti-file directory entries having an attribute indicating there is no real data file corresponding to the entry. Entries may-be moved between directories and when an anti-file and a data file of the same name are present in the same directory, the real data file is deleted. This enables the synchronization of sets of target and source files to take account of changes.

Abstract: An airbag initiator having an ignition charge and a low temperature ignition charge in an inner case and a metal header closing the inner case, a glass seal providing feed through of one or more electrical connections to the ignition charge through the header. The seal is preferably formed using glass material. A ceramic base supports the header and their spaced relationship maintained by a single continuous glass seal. The ceramic base and glass seal electrically isolates the header and ignition charge against accidental ignition. The ceramic to glass to metal seal provides protection against leakage of unfiltered gas from the inflator system. A ferromagnetic pressed material is assembled into the ceramic base and it's spaced relationship to the ceramic body and the electrical connections are maintained by a single continuous glass seal.

Abstract: A shrouding apparatus, suspended from a bottom pour vessel carries a vertical shroud tube at one end for surrounding a molten metal pouring stream and a counterweight at its other end to force the shroud tube against the bottom of the pouring vessel. The apparatus includes means for introducing a protective atmosphere to the interior of the shroud.

Abstract: Means for controlling the speed of the secondary of a linear motor, particularly the shuttle of a linear motor powered loom, consists of a series of uniformly spaced markings on the secondary and a sensor responsive to the markings and located adjacent to the linear motor primary. The markings cause the sensor to produce an oscillating output, the frequency of which is dependent on the speed of the secondary. A control signal derived from the sensor output is used to turn off the supply of current to the linear motor primary when the secondary is travelling at the required speed.

Abstract: To reduce the effects of noise in stereo audio apparatus, cross talk is introduced between the output channels in a frequency sensitive manner, the amount of cross talk being controlled in accordance with an input or output signal level on the level of two or more combined signals.