1. A seal assembly, comprising:
a first body;
a second body;
a non-weeping primary seal disposed between the first body and the second body and adapted to seal critical pressure coming from a single direction;
a redundant secondary seal, serving no other purpose but to back up the primary seal in the event of failure of the primary seal, disposed between the first body and the second body in spaced relation to the primary seal and shielded from the critical pressure by the primary seal;
a non-weeping pressure port extending through one of the first body or the second body between the primary seal and the secondary seal; and
means for detecting a pressure increase within the pressure port, thereby indicating a failure of the primary seal.
2. The seal assembly as defined in claim 1, wherein the second body is positioned within the first body.
3. The seal assembly as defined in claim 2, wherein the second body is a shaft which does one of reciprocates or rotates.
4. The seal assembly as defined in claim 3, wherein both the primary seal and the secondary seals are annular seals.
5. A seal assembly, comprising:
a first body;
a second body in the form of a shaft disposed within the first body, the shaft being capable of one of reciprocating or rotating;
a non-weeping primary seal grouping including several annular seals disposed between the first body and the second body, and adapted to seal critical pressure coming from a single direction;
a redundant secondary seal grouping serving no other purpose but to back up the primary seal grouping in the event of failure of the primary seal grouping, the secondary seal grouping including several annular seals disposed between the first body and the second body in spaced relation to the primary seal grouping and shielded from the critical pressure by the primary seal grouping;
a non-weeping pressure port extending through the first body between the primary seal grouping and the secondary seal grouping; and
a pressure sensor for detecting an increase in pressure within the pressure port, thereby indicating a failure of the primary seal grouping.
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 method for a node to join a wireless ad-hoc network, comprising:
invoking a permit-to-join command on an input unit of a target node to start a joined procedure of the target node;
sending a join request message by a new node to start the join procedure of the new node;
starting a permit-to-be-joined timer;
determining whether the permit-to-be-joined timer reaches a predetermined permit-to-be-joined time limit, and terminating the joined procedure of the target node if the permit-to-be-joined timer reaches the predetermined permit-to-be-joined time limit;
sending a join response message by the target node and issuing a joined prompt on an indication unit of the target node, wherein when the new node receives the join response message, an indication unit of the new node issues a join prompt;
determining whether the joined prompt of the target node and the join prompt of the new node are correspondingly issued; and
if the joined prompt of the target node and the join prompt of the new node are not correspondingly issued, a reject-to-be-joined command is invoked on the input unit of the target node issuing the joined prompt to cancel the joined procedure of the target node, or a reject-to-join command is invoked on an input unit of the new node issuing the join prompt to cancel the join procedure of the new node.
2. A method for a node to join a wireless ad-hoc network, suitable for connecting a new node among a plurality of candidate new nodes to a target node in a target wireless ad-hoc network, wherein the candidate new nodes and the target node respectively equipped with an input unit and an indication unit, the method for joining the new node to the wireless ad-hoc network comprising:
(a) receiving a permit-to-join command from the input unit of the target node to start a joined procedure of the target node, starting a permit-to-be-joined timer, determining whether the permit-to-be-joined timer reaches a predetermined permit-to-be-joined time limit; and terminating the joined procedure if the permit-to-be-joined timer reaches the predetermined permit-to-be-joined time limit;
(b) receiving a join request message from one of the candidate new nodes by the target node during the joined procedure;
(c) sending a join response message from the target node which receives the join request message to said one of the candidate new nodes during the joined procedure, and issuing a joined prompt on the indication unit of the target node, wherein when said one of the candidate new nodes receives the join response message, the indication unit of this candidate new node issues a join prompt;
(d) determining whether the joined prompt of the target node and the join prompt of the new node are correspondingly issued during the step (c); and
(e) invoking a reject-to-be-joined command from the input unit of the target node if the joined prompt of the target node and the join prompt of the new node are not correspondingly issued during the step (d).
3. The method according to claim 2 further comprising creating a not-permitted-to-join address list on the target node.
4. The method according to claim 3, wherein in the step (c), the target node sends the join response message to said one of the candidate new nodes only when said one of the candidate new nodes is not in the not-permitted-to-join address list of the target node.
5. The method according to claim 3, wherein after the step (e), the method further comprises:
adding the address of said one of the candidate new node to the not-permitted-to-join address list.
6. The method according to claim 5 further comprising deleting the addresses from the not-permitted-to-join address list by using the input unit of the target node.
7. The method according to claim 2 further comprising creating a permitted-to-join address list on the target node.
8. The method according to claim 7 further comprising:
determining whether the addresses of the candidate new nodes appear in the permitted-to-join address list, wherein the candidate new nodes are allowed to join the target node if the addresses of the candidate new nodes appear in the permitted-to-join address list.
9. The method according to claim 8 further comprising deleting addresses from the permitted-to-join address list by using the input unit of the target node.
10. The method according to claim 2 further comprising measuring signal quality of the candidate new nodes on the target node, and sending the join response message to one of the candidate new nodes according to the measured signal quality.
11. The method according to claim 2 further comprising determining whether an unanticipated connection occurs before the new node joins the target node.
12. A method for a node to join a wireless ad-hoc network, suitable for a new node to join a target node among a plurality of candidate target nodes, wherein a joined procedure of the target node is started, and the new node and the candidate target nodes respectively equipped with an input unit and a indication unit, the method comprising:
(a) starting a permit-to-be-joined timer;
(b) determining whether the permit-to-be-joined timer reaches a predetermined permit-to-be-joined time limit, and terminating the joined procedure of the target node if the permit-to-be-joined timer reaches the predetermined permit-to-be-joined time limit;
(c) sending a join request message from the new node to one of candidate target nodes during the joined procedure;
(d) receiving a join response message from said one of the candidate target nodes by the new node and issuing a join prompt on the indication unit of the new node during the joined procedure, wherein the indication unit of said one of the candidate target nodes issues a joined prompt after said one of the candidate target node issues the join response message;
(e) determining whether the joined prompt of the target node and the join prompt of the new node are correspondingly issued during the joined procedure; and
(f) receiving a reject-to-join command from the input unit of the new node during the joined procedure if the joined prompt of the target node and the join prompt of the new node are not correspondingly issued.
13. The method according to claim 12 further comprising creating a not-permitted-to-be-joined address list on the new node.
14. The method according to claim 13, wherein in the step (c), the address of said one of the candidate target nodes does not appear in the not-permitted-to-be-joined address list.
15. The method according to claim 13, wherein the step (f) further comprises:
adding the address of said one of the candidate target nodes to the not-permitted-to-be-joined address list.
16. The method according to claim 15 further comprising deleting addresses in the not-permitted-to-be-joined address list by using the input unit of the new node.
17. The method according to claim 12 further comprising creating a permitted-to-be-joined address list on the new node.
18. The method according to claim 17 further comprising:
determining whether the addresses of the candidate target nodes appear in the permitted-to-be-joined address list, wherein the new node is allowed to join the candidate target nodes if the addresses of the candidate target nodes appear in the permitted-to-be-joined address list.
19. The method according to claim 18 further comprising deleting an address in the permitted-to-be-joined address list by using the input unit of the new node.
20. The method according to claim 12 further comprising measuring signal quality of the candidate target nodes on the new node, and issuing the join request message to one of the candidate target nodes according to the measured signal quality.
21. The method according to claim 12 further comprising determining whether an unanticipated connection occurs before the new node joins the target node.
22. A wireless ad-hoc network system, suitable for a wireless ad-hoc network, the wireless ad-hoc network system comprising:
a target node, already joined a target wireless ad-hoc network and equipped with a first input unit and a first indication unit, wherein the first input unit is used for receiving a permit-to-join command to start a joined procedure on the target node; and
a new node, equipped with a second input unit and a second indication unit, wherein the new node automatically sends a join request message to start the join procedure on the new node,
wherein the target node starts a permit-to-be-joined timer and determines whether the permit-to-be-joined timer reaches a predetermined permit-to-be-joined time limit,
wherein the target node terminates the joined procedure of the target node if the permit-to-be-joined timer reaches the predetermined permit-to-be-joined time limit,
wherein when the target node sends a join response message, the first indication unit issues a joined prompt, and when the new node receives the join response message, the second indication unit issues a join prompt,
wherein if the joined prompt on the first indication unit and the join prompt on the second indication unit are not correspondingly issued during the join procedure, the first input unit or the second input unit is further used for receiving the reject-to-join command to cancel the joined procedure on the target node or the join procedure on the new node.
23. The wireless ad-hoc network system according to claim 22, wherein the target wireless ad-hoc network is a network conforming to a ZigBee standard.
24. The wireless ad-hoc network system according to claim 23, wherein the target node is a ZigBee coordinator or a ZigBee router.
25. The wireless ad-hoc network system according to claim 23, wherein the new node is a ZigBee router or a ZigBee end device.
26. The wireless ad-hoc network system according to claim 23, wherein the first input unit and the second input unit respectively comprise a button or a graphic user interface (GUI).
27. The wireless ad-hoc network system according to claim 23, wherein the first indication unit and the second indication unit respectively comprise a sound producing device, a light emitting diode (LED) light, or a liquid crystal display (LCD).