Abstract:
A vacuum pump system (10; 36; 46) for pumping gas from an enclosure (12) comprises: a vacuum pump unit (14) having a pump inlet (16) connectable with an outlet (18) of such an enclosure and a pump outlet (20) for exhausting gas; and a chamber (22; 50) selectively connectable with the pump inlet and the pump outlet, such that, in use, in a first state gas can be pumped from the chamber to the pump inlet by the vacuum pump unit and in a second state gas can be evacuated from the pump outlet to the chamber to reduce pressure at the pump outlet.A method of controlling the vacuum pump system (10; 36; 46) comprises a first step of pumping gas from the chamber to the pump inlet using the vacuum pump unit and a second step of allowing gas to be evacuated from the pump outlet to the chamber to reduce pressure at the pump outlet.
Abstract:
A multi-stage vacuum pump may include first and second half-shell components defining a plurality of pumping chambers and for assembly together along respective longitudinal extending faces; first and second end stator components for assembly at respective longitudinal seals for sealing between the first and second half-shell stator components when assembled together at the longitudinally extending faces; and annular seals for sealing between the first and second end stator components and the first and second half-shell stator components when assembled; wherein the longitudinal seals have end portions which abut against the annular seals for sealing therebetween and the first and second half-shell stator components have formations for resisting movement of the end portions away from the annular seals when the end portions are compressed between the first and second half-shell stator components.
Abstract:
An image tile server importantly includes an image tile cache, to support a tiled map display in a user device. Instead of the conventional user device client (e.g., an Ajax client) making image requests directly to a mapping server (MS), a display device initiates an image request of a tile server (TS), and the tile server returns the requested image. However, importantly, the tile server (TS) also retains a cached copy of the returned image for faster retrieval at a later time relating to another image request by the same or different user device.
Abstract:
A screw pump includes a stator having a fluid inlet and a fluid outlet, the stator housing first and second externally threaded, tapered rotors mounted on respective shafts and adapted for counter-rotation within the stator to compress fluid passing from the fluid inlet to the fluid outlet, wherein the threads have a pitch that increases towards the fluid outlet.
Abstract:
This invention relates to a cellular communication system (200), billing processor (223) and method of billing. The communication system includes a subscriber unit (201) having a user updateable identity to phone number association table used for dialling phone numbers based on an identity such as a name. It also includes means (203, 205,219,217) for communicating the table to a billing processor (223) being part of the fixed network. The billing processor (223) comprises means (227) for receiving the table and generating a billing association table containing information from the identity to phone number association table. It furthermore comprises a billing report generator (225) for generating a billing report for the subscriber unit (201) including identity information derived from the billing association table. The invention is applicable to cellular communication systems such as UMTS.