Abstract: Bounding cell reorder depth is disclosed. It is determined whether a reorder buffer exceeds a depth limit. If the reorder buffer exceeds the depth limit, backpressure is sent with respect to a source associated with the reorder buffer by including in a cell being sent into a switch fabric with which the reorder buffer is associated source based backpressure information stored in a location in the cell that is normally used by the switch fabric to send information to ports associated with the switch fabric and normally is not used by the ports when sending cells into the switch fabric.

Abstract: A fabric access device comprising a plurality of system interfaces is disclosed. The fabric access device includes a fabric interface configured to receive data from and send data to a switch fabric and a routing circuit configured to send data received on one of the plurality of system interfaces to the switch fabric via the fabric interface. The inclusion of a plurality of system interfaces facilitates a variety of configurations that provide different levels of redundancy and optimize use of available bandwidth.

Abstract: Network traffic switching comprises: for each of a plurality of classes, specifying a next queue to be serviced within that class, selecting from among the classes a next class to be serviced, and sending data from the next queue of the next class to be serviced via an egress link.

Abstract: A technique for providing access to a switch fabric is disclosed. In some embodiments, the method comprises determining scheduling information specific to a link to the switch fabric and using the scheduling information to determine a queue to be serviced by the link. In some embodiments, the system comprises a buffer configured to store a plurality of queues, and a queue scheduler associated with the buffer and configured to determine scheduling information specific to a link to the switch fabric and use the scheduling information to select one of the plurality of queues as the next queue to be serviced by the link.

Abstract: Transferring data via a switch fabric comprises: for each unit of data to be transferred, selecting one of a plurality of links from a fabric access node to the switch fabric to transfer the unit of data, and in the event that one or more of the plurality of links become unavailable, such that one or more remaining links remain available for transferring data, transferring a subsequently received unit of data via one of the remaining links.

Abstract: Network data switching comprises receiving a cell, associating the cell with a destination port, selecting an egress link that has been soft configured to be associated with the destination port, and switching the cell to the selected egress link. A network switch comprises an ingress link configured to receive a cell and a switch circuit coupled to the ingress link, configured to associate the cell with a destination port, to select an egress link that has been soft configured to be associated with the destination port, and to switch the cell to the egress link.

Abstract: An anode monitoring system for monitoring the integrity of anodes 2 provided on a metallic structure such as a pipeline system 1. A signal circuit Sn including the pipeline 1 and one of the anodes 2 is set up and appropriate signals are looked for at a central station 4. Reception of the signal at the central station 4 is dependent on the integrity of the anode 2 under inspection at that time. If the anode 2 is missing or defective the expected signal is not received and thus the fault in the anode 2 can be detected. A notch filter 5 is inserted in series between each anode 2 and the pipeline 1. The filter 5 provides a high impedance which can be signalled across but does not interfere with the cathodic protection system.

Abstract: A two-lever toggle mechanism operates in conjunction with a conventional toggle bracket of an I/O station to prevent the incorrect loading of a DLT cartridge into a dedicated pass-through slot. A rotating front lever includes a leading protrusion facing the slot and a front wing that cooperates with the toggle bracket to prevent its closure when an incorrectly loaded cartridge is present in the slot. A rotating rear lever similarly incorporates a trailing protrusion facing the slot and a shank slidably coupled to an elongated groove in the front lever, such that the two levers rotate together. Therefore, the trailing protrusion provides an additional safeguard to ensure that only a DLT cartridge that is placed correctly into the slot permits the closure of the toggle bracket.

Abstract: An anode monitoring system for monitoring the integrity of anodes 2 provided on a metallic structure such as a pipeline system 1. A signal circuit Sn including the pipeline 1 and one of the anodes 2 is set up and appropriate signals are looked for at a central station 4. Reception of the signal at the central station 4 is dependent on the integrity of the anode 2 under inspection at that time. If the anode 2 is missing or defective the expected signal is not received and thus the fault in the anode 2 can be detected. A notch filter 5 is inserted in series between each anode 2 and the pipeline 1. The filter 5 provides a high impedance which can be signalled across but does not interfere with the cathodic protection system.

Abstract: Coupling apparatus for allowing transmission of electrical signals between a flowline (1) and a communications unit (4). The coupling apparatus comprises first (5) and second (8) portions of magnetic material. The first portion is arranged to receive the second portion and at least partially defines a flowline receiving aperture. The first and second portions (5,8) together form a magnetic circuit around the aperture and the second portion carries a winding (9) arranged for electrical connection to the communications unit (4). The winding links with the magnetic circuit when the second portion (8) is received in the first (5) such that an alternating current in the winding will generate a corresponding current in a flowline disposed in the aperture and vice versa. The arrangement allows the first portion to be permanently mounted on a flowline and the second portion to be inserted in situ.

Abstract: A two-lever toggle mechanism operates in conjunction with a conventional toggle bracket of an I/O station to prevent the incorrect loading of a DLT cartridge into a dedicated pass-through slot. A rotating front lever includes a leading protrusion facing the slot and a front wing that cooperates with the toggle bracket to prevent its closure when an incorrectly loaded cartridge is present in the slot. A rotating rear lever similarly incorporates a trailing protrusion facing the slot and a shank slidably coupled to an elongated groove in the front lever, such that the two levers rotate together. Therefore, the trailing protrusion provides an additional safeguard to ensure that only a DLT cartridge that is placed correctly into the slot permits the closure of the toggle bracket.

Abstract: A lockout lever is hinged on the side of a slot in an I/O station of an automated library. The lever includes a leading blade and a trailing blade that protrude into the slot. The leading blade is urged open by a spring. When an LTO cartridge or a DLT cartridge in the wrong position is introduced into the slot, the forward motion of the cartridge is impeded by its substantially flat side that faces both the leading and trailing blades and prevents rotation of the lockout lever. When a DLT cartridge is introduced correctly, the cavity in its side accommodates the leading blade as the trailing blade is pushed out of the slot. The leading blade is sized to clear the gap in the door hinge of the DLT cartridge when removed from the interior of the station.

Abstract: A subsurface object location apparatus for determining the position of an object 2 located below a surface S such as a land surface, the surface of the sea or a seabed. A subsurface unit 1 having transmitter means for transmitting inductive signals is mounted on the object 2. A plurality of surface units 3 are disposed at spaced locations at the surface S. Each surface unit 3 has receiver means arranged for receiving the inductive signals. Processing means 4 are provided for determining the location of the object 2 using time difference of arrival techniques in respect of the signals received at the surface units. Cyclic correlation is used in determining the times of reception of signals at the surface units.

Abstract: In a graphical user interface for accessing a large number of files, such as text files, graphics files, or spreadsheets, a system allows quick glances of “thumbnails” or highly reduced versions of the files. When a folder is opened, every file in the folder is opened as a background operation and thumbnail data, such as a reduced image or text summary of the file, is derived and retained in a cache folder for quick access. When a cursor is touched, without a mouse-click, to a particular icon in the opened folder, the thumbnail for the file identified by the icon is accessed from the cache folder and displayed.

Abstract: A data transmission system for use in extracting data from a downhole location in a well is disclosed. The well has electrically conductive downhole structure (2,C) which together with an earth return forms a signal circuit which is used to transmit data. A current source (34) is provided at the wellhead for applying a reference signal to the downhole structure (2,C). Effective impedance varying means (48) are located downhole and used for varying the effective impedance of the signal circuit in dependence on data to be transmitted to the wellhead. Monitoring means (35) for monitoring changes in the reference signal caused by varying the effective impedance of the signal circuit are located at the wellhead. Monitoring these changes allows data to be extracted. A separate reference earthing point may be provided for the monitoring means to alleviate the effect of imperfections in the earth connection (S) used to complete the signal circuit.

Abstract: Data transmission in pipeline systems A first set of apparatus is arranged for transmitting data from a point in a cased section of a well 1, 3 to a remote location. The apparatus may be used as a relay station 6 to increase operational depth. Signals are applied to and received from the string 1 at the relay station 6 and a selected length of the string 1 is provided with insulating spacer means 9 on either side of the relay station to ensure that the string 1 and casing 3 are effectively isolated for a selected minimum distance. This enables potential differences to be both applied to and detected from the string 1, thus allowing data transmission and reception. A second set of apparatus is arranged for transmitting from an internal unit 408 inside a cased section of the well 401, 403 to the immediate surrounding area outside the casing 403. The internal unit 408 injects current into the string 401. A toroid 415 which surrounds the casing 403 is provided to pick up signals.

Abstract: An anode monitoring system for monitoring the integrity of anodes 2 provided on a metallic structure such as a pipeline system 1. A signal circuit Sn including the pipeline 1 and one of the anodes 2 is set up and appropriate signals are looked for at a central station 4. Reception of the signal at the central station 4 is dependent on the integrity of the anode 2 under inspection at that time. If the anode 2 is missing or defective the expected signal is not received and thus the fault in the anode 2 can be detected. A notch filter 5 is inserted in series between each anode 2 and the pipeline 1. The filter 5 provides a high impedance which can be signalled across but does not interfere with the cathodic protection system.

Abstract: A subsurface object location apparatus for determining the position of an object 2 located below a surface S such as a land surface, the surface of the sea or a seabed. A subsurface unit 1 having transmitter means for transmitting inductive signals is mounted on the object 2. A plurality of surface units 3 are disposed at spaced locations at the surface S. Each surface unit 3 has receiver means arranged for receiving the inductive signals. Processing means 4 are provided for determining the location of the object 2 using time difference of arrival techniques in respect of the signals received at the surface units. Cyclic correlation is used in determining the times of reception of signals at the surface units.

Abstract: An apparatus and method for detecting and locating electric current leakage paths along the length of an electrically conducting elongate member. The apparatus has a variable supply device and a meter device for monitoring the impedance of the member (9, 11), the supply device being operable to drive current in opposite directions along the member, so that a movable node can be established, the node being where the net change in potential between the member and its surroundings is substantially zero. When the apparatus is in use, the position of the node is varied by varying the current driven along the member and the resultant impedance is monitored by the monitoring meter device, whereby the position of the node at which there is a local minimum in the impedance indicates the position of a current leakage path.

Abstract: A protection circuit for an excitation current source protects against excessive compliance voltage by using a cascode transistor between the current source and an output terminal, and a transistor coupled to the output terminal and to the control lead of the cascode transistor to cause the cascode transistor to turn off if the voltage exceeds a threshold level.