1. An active retractable seal assembly configured for use between a rotating component and a stationary component of a turbomachinery, comprising:
a seal mounted to the stationary component, wherein the seal is movable towards and away from the rotating component between a respective closed position and an open position as a function of pressure drop across the seal; the seal comprising:
an active seal segment;
a non-active seal segment; and
a fluid by-pass circuit for directing fluid around the active seal segment to reduce pressure drop across the active seal segment thereby resulting in the active seal segment moving towards an open position under the action of one or more biasing devices while maintaining the non-active seal segment in a closed position.
2. The seal assembly of claim 1, further comprising one or more first biasing devices disposed between the non-active seal segment and the stationary component.
3. The seal assembly of claim 2, wherein the one or more first biasing devices are configured for biasing the non-active seal segment towards a closing position in which the non-active seal segment contacts the rotating component.
4. The seal assembly of claim 2, wherein the one or more first biasing devices are configured for biasing the non-active seal segment towards an open position in which the non-active seal segment does not contact the rotating component.
5. The seal assembly of claim 1, further comprising one or more second biasing devices disposed between the active seal segment and the non-active seal segment.
6. The seal assembly of claim 5, wherein the one or more second biasing devices are configured for biasing the active seal segment towards an open position in which the active seal segment does not contact the rotating component.
7. The seal assembly of claim 1, wherein the active seal segment is disposed radially inward within the non-active seal segment.
8. The seal assembly of claim 1, wherein the by-pass circuit comprises a conduit extending from a location upstream of the active seal segment, via the stationary component, to a location downstream of the active seal segment.
9. The seal assembly of claim 8, wherein the by-pass circuit comprises a manually or automatically controlled valve coupled to the conduit and configured to control flow of fluid through the conduit.
10. The seal assembly of claim 9, wherein the active seal segment is moved to an open position by opening the valve.
11. The seal assembly of claim 9, wherein the active seal segment is moved to a closed position by closing the valve.
12. An active retractable seal assembly configured for use between a rotor and a stator of a turbine, comprising:
a seal mounted to the stator, wherein the seal is movable towards and away from the rotor between a respective closed position and an open position as a function of pressure drop across the seal; the seal comprising:
an active seal segment;
a non-active seal segment; and
a fluid by-pass circuit for directing fluid around the active seal segment to reduce pressure drop across the active seal segment thereby resulting in the active seal segment moving towards an open position under the action of one or more biasing devices while maintaining the non-active seal segment in a closed position.
13. The seal assembly of claim 12, wherein the active seal segment comprises an abradable active seal segment.
14. The seal assembly of claim 12, wherein the non-active seal segment comprises an abradable non-active seal segment.
15. The seal assembly of claim 12, wherein the active seal segment is disposed radially inward within the non-active seal segment.
16. The seal assembly of claim 12, wherein the by-pass circuit comprises a conduit extending from a location upstream of the active seal segment, via the stator, to a location downstream of the active seal segment.
17. The seal assembly of claim 12, wherein the by-pass circuit comprises a conduit extending from the non-active seal segment to the stator.
18. The seal assembly of claim 17, wherein the by-pass circuit comprises a manually or automatically controlled valve coupled to the conduit and configured to control flow of fluid through the conduit.
19. The seal assembly of claim 18, wherein the active seal segment is moved to an open position by opening the valve.
20. The seal assembly of claim 18, wherein the active seal segment is moved to a closed position by closing the valve.
21. An active retractable seal assembly configured for use between a rotating component and a stationary component of a turbomachinery, comprising:
a seal mounted to the stationary component, wherein the seal is movable towards and away from the rotating component between a respective closed position and an open position as a function of pressure drop across the seal; the seal comprising:
a non-active seal segment;
an active seal segment disposed radially within the non-active seal segment; wherein the active seal segment is movable towards and away from the rotating component between a respective closed position and an open position relative to the non-active seal segment; and
a fluid by-pass circuit for directing fluid around the active seal segment to reduce pressure drop across the active seal segment thereby resulting in the active seal segment moving towards an open position under the action of one or more biasing devices while maintaining the non-active seal segment in a closed position.
22. The seal assembly of claim 21, wherein the active seal segment is movably disposed within a cavity of the non-active seal segment.
23. A method for actively controlling a seal mounted to a stationary component and movable towards and away from a rotating component between a respective closed position and an open position as a function of pressure drop across the seal in a turbomachinery, the method comprising:
establishing a fluid by-pass circuit around an active seal segment of the seal;
controlling the bypass circuit to selectively admit a process fluid through the by-pass circuit to reduce the pressure drop across the active seal segment, resulting in the active seal segment moving away from the rotating component under the action of one or more biasing devices while maintaining contact between a non-active seal segment of the seal and the rotating component.
24. The method of claim 23, wherein controlling the by-pass circuit comprises controlling a valve coupled to a conduit extending from a location upstream of the active seal segment, via the stationary component, to a location downstream of the active seal segment so as to control flow of the fluid through the conduit to reduce the pressure drop across the active seal segment.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A multicastbroadcast method comprising:
receiving an Internet Protocol (IP) packet from an upper layer;
determining whether the received IP packet comprises at least one of a multicast destination address and a broadcast destination address; and
transmitting a packet in which a connection identifier (CID) for the multicast or the broadcast is selectively attached to the received IP packet according to a result of the determination.
2. The method of claim 1, wherein the multicastbroadcast method is performed in a downlink from a base station to a mobile station.
3. The method of claim 1, wherein the multicastbroadcast method is performed in a convergence sublayer, convergence sublayer comprising an upper layer of a Media Access Control (MAC) layer which is operated in a base station.
4. The method of claim 3, further comprising:
inserting the packet comprising the CID for the multicast or the broadcast into a mobile anchor point (MAP) message, the MAP message comprising a MAC management message, in the MAC layer.
5. The method of claim 4, wherein specific mobile stations, in an area of coverage of the base station receive the packet comprising the CID, the packet comprising a multicast packet or nonspecific mobile stations, in the area of the coverage of the base station, receive the packet attached with the CID, which is a broadcast packet.
6. The method of claim 1, wherein the multicastbroadcast method is applied to a portable Internet system in accordance with at least one of Institute of Electrical and Electronics Engineers (IEEE) 802.16de, wireless broadband Internet (WiBro), and World Interoperability for Microwave Access (WiMAX).
7. A multicastbroadcast method comprising:
receiving an Internet Protocol (IP) packet from a mobile station;
determining whether the received IP packet comprises at least one of a first connection identifier (CID) for the multicast and the broadcast; and
transmitting a packet in which the first CID of the received IP packet is selectively replaced with a second CID according to a result of the determination.
8. The method of claim 7, wherein the multicastbroadcast method is performed in an uplink from a mobile station to a base station.
9. The method of claim 7, wherein the multicastbroadcast method is performed in a convergence sublayer, the convergence sublayer comprising an upper layer of a Media Access Control (MAC) layer which is operated in a base station.
10. The method of claim 9, further comprising:
inserting the packet in which the first CID is replaced with the second CID in a mobile anchor point (MAP) message, the Map message comprising a MAC management message, in the MAC layer.
11. The method of claim 10, wherein specific mobile stations, in an area of the coverage of the base station, receive the packet in which the first CID is replaced with the second CID, which is a multicast packet, or
nonspecific mobile stations, in the area of the coverage of the base station, receive the packet in which the first CID is replaced with the second CID.
12. The method of claim 7, wherein the multicastbroadcast method is applied to a portable Internet system in accordance with at least one of Institute of Electrical and Electronics Engineers (IEEE) 802.16de, wireless broadband Internet (WiBro), and World Interoperability for Microwave Access (WiMAX).
13. A multicastbroadcast apparatus comprising:
a classifier for generating determination information comprising an indication whether an Internet Protocol (IP) packet which is received from an upper layer comprises a multicast destination address or a broadcast destination address; and
a transmission unit for transmitting a packet in which a connection identifier (CID) for the multicast or the broadcast is selectively attached to the received IP packet according to the determination information.
14. The multicastbroadcast apparatus of claim 13, wherein the multicastbroadcast apparatus supports a downlink from a base station to mobile stations.
15. The multicastbroadcast apparatus of claim 13, wherein a convergence sublayer that is an upper layer of a Media Access Control (MAC) layer which is operated in a base station comprises the multicastbroadcast apparatus.
16. The multicastbroadcast apparatus of claim 13, further comprising:
a Media Access Control (MAC) layer for inserting the packet attached with the CID for the multicast or the broadcast into a mobile anchor point (MAP) message, the MAP comprising a MAC management message.
17. The multicastbroadcast apparatus of claim 13, wherein specific mobile stations, in an area of coverage of the base station, receive the packet attached with the CID, the packet comprising a multicast packet, or
nonspecific mobile stations, in the area of coverage of the base station, receive the packet attached with the CID, the packet comprising a broadcast packet.
18. The multicastbroadcast apparatus of claim 13, wherein the multicastbroadcast apparatus is applied to a portable Internet system in accordance with at least one of Institute of Electrical and Electronics Engineers (IEEE) 802.16de, wireless broadband Internet (WiBro), and World Interoperability for Microwave Access (WiMAX).
19. A multicastbroadcast apparatus comprising:
a classifier for generating determination information comprising an indication whether an Internet Protocol (IP) packet which is received from a mobile station comprises at least one of a first connection identifier (CID) for a multicast destination address and a broadcast destination address; and
a transmission unit for transmitting a packet in which the first CID of the received IP packet is selectively replaced with a second CID according to the generated determination information.
20. The multicastbroadcast apparatus of claim 19, wherein the multicastbroadcast apparatus supports an uplink from the mobile station to a base station.
21. The multicastbroadcast apparatus of claim 19, wherein a convergence sublayer that is an upper layer of a MAC layer which is operated in the base station comprises the multicastbroadcast apparatus.
22. The multicastbroadcast apparatus of claim 19, further comprising:
a Media Access Control (MAC) layer for inserting the packet in which the first CID is replaced with the second CID in a mobile anchor point (MAP) message, the MAP message comprising a MAC management message.
23. The multicastbroadcast apparatus of claim 19, wherein specific mobile stations, in an area of the coverage of the base station, receive the packet in which the first CID is replaced with the second CID, the packet comprising a multicast packet, or
nonspecific mobile stations, in the area of the coverage of the base station, receive the packet in which the first CID is replaced with the second CID.
24. The multicastbroadcast apparatus of claim 19, wherein the multicastbroadcast apparatus is applied to a portable Internet system in accordance with to at least one of Institute of Electrical and Electronics Engineers (IEEE) 802.16de, wireless broadband Internet (WiBro), and World Interoperability for Microwave Access (WiMAX).