1. A content distribution system, comprising a center server and a plurality of terminal devices connectable to the center server, wherein
the center server includes a section for specifying, from among a plurality of content portions into which a content item is divided, a target content portion to be received next by a recipient terminal device being one of the plurality of terminal devices, the target content portion being immediately before or immediately after one or more content portions already stored in the recipient terminal device;
the center server includes a section for specifying a sender terminal device being one of the plurality of terminal devices that stores the specified target content portion; and
each terminal device includes a section for receiving and storing the specified target content portion from the specified sender terminal device.
2. The content distribution system according to claim 1, further comprising a content server to which the plurality of terminal devices can be connected, wherein:
the content server includes a section for storing the content portions;
the content server includes a section for sending each of the content portions to a different terminal device; and
each terminal device includes a section for storing the content portion sent from the content server.
3. A center server to which a plurality of terminal devices can be connected, comprising:
a section for specifying, from among a plurality of content portions into which a content item is divided, a target content portion to be received next by a recipient terminal device being one of the plurality of terminal devices, the target content portion being immediately before or immediately after one or more content portions already stored in the recipient terminal device; and
a section for specifying one of the plurality of terminal devices that stores the specified target content portion, as a sender terminal device for sending the specified target content portion to the recipient terminal device.
4. The center server according to claim 3, further comprising a section for receiving and storing operation status information from each of the terminal devices,
wherein the sender terminal device specifying section specifies the sender terminal device based on the operation status information of the terminal devices.
5. The center server according to claim 3, wherein if there are a plurality of terminal devices specified as sender terminal devices, the sender terminal device specifying section narrows down the sender terminal devices based on a transfer efficiency between the recipient terminal device and each sender terminal device.
6. The center server according to claim 3, further comprising a section for storing a difference value between the number of remaining earlier portions and the number of remaining later portions for each terminal device, wherein the number of remaining earlier portions represents the number of earlier content portions that have not been stored in the terminal device and the number of remaining later portions represents the number of later content portions that have not been stored in the terminal device,
wherein the content portion specifying section chooses either a content portion immediately before the one or more already-stored content portions or a content portion immediately after the one or more already-stored content portions based on a sum of the difference values for all the terminal devices.
7. The center server according to claim 6, wherein if the sender terminal device cannot be specified, the content portion specifying section chooses either a content portion immediately before the one or more already-stored content portions or a content portion immediately after the one or more already-stored content portions based on the difference value for the recipient terminal device.
8. The center server according to claim 3, being connectable to a content server storing the content item and further comprising:
a section for calculating a divisor being the number of portions into which the content item is divided, based on a bandwidth of a communications line to which the content server is connected and a transfer rate at which the content item is sent from the content server;
a section for instructing the content server to divide the content item into a plurality of content portions based on the calculated divisor; and
a section for instructing each terminal device to receive different one of the content portions from the content server.
9. A terminal device connectable to a center server, the center server being capable of specifying, from among a plurality of content portions into which a content item is divided, a target content portion to be received next by the terminal device, the target content portion being immediately before or immediately after one or more content portions already stored in the terminal device, and capable of specifying, from among a plurality of terminal devices, a sender terminal device that stores the specified target content portion, the terminal device comprising:
a receiving section for receiving and storing the specified target content portion from the specified sender terminal device; and
a sending section for sending the one or more content portions already stored in the terminal device to another terminal device.
10. A computer program for a center server to which a plurality of terminal devices can be connected, the computer program instructing the center server to perform the steps of:
specifying, from among a plurality of content portions into which a content item is divided, a target content portion to be received next by a recipient terminal device being one of the plurality of terminal devices, the target content portion being immediately before or immediately after one or more content portions already stored in the recipient terminal device; and
specifying one of the plurality of terminal devices that stores the specified target content portion, as a sender terminal device for sending the specified target content portion to the recipient terminal device.
11. A computer program for a terminal device connectable to a center server, the center server being capable of specifying, from among a plurality of content portions into which a content item is divided, a target content portion to be received next by the terminal device, the target content portion being immediately before or immediately after one or more content portions already stored in the terminal device, and being capable of specifying, from among a plurality of terminal devices, a sender terminal device that stores the specified target content portion, the computer program instructing the terminal device to perform the steps of:
receiving and storing the specified target content portion from the specified sender terminal device; and
sending the one or more content portions already stored in the terminal device to another terminal device.
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 coupling assembly comprising;
a coupler body having a generally cylindrical shape and an opening at one end, the coupler body having an inner wall with an inner circumference and an outer wall;
a conduit having a generally cylindrical shape complementary to the coupler body, the conduit having an inner wall and an outer wall with an outer circumference and an opening at its end, the outer wall of the conduit having dimensions and shape so that it fits snugly inside the inner wall of the coupler body;
an abutment extending from the coupler body or the conduit to limit the extent to which the conduit may be extended into the coupler body;
a coupler key groove extending along the inner circumference of the inner wall of the coupler body, the coupler key groove being located axially away from the opening in the coupler body;
an aperture connecting the coupler key groove with the outer wall of the coupler;
a conduit key groove extending along the outer circumference of the outer wall of the conduit, the conduit key groove having a shape that is complementary to the coupler key groove, the conduit key groove being spaced from its end a distance which allows it to align with the coupler key groove when the end of the conduit abuts against the abutment along the inner wall of the coupler body;
the coupler key groove and conduit key groove, when they are aligned forming a parallelogram passageway with acute angles; and
a locking key which fits therein having a parallelogram cross section with acute angles that is complementary with of the coupler key groove and conduit key groove, each acute angle of the locking key being greater or less than the complementary acute angle of the coupler body key groove so that the acute angles of the locking key tend to engage tightly the coupler key groove and the conduit key groove if tensile forces are applied to separate the coupler, and the locking key has a length so that it may be inserted into the aperture and engage the coupler key groove and the conduit key groove.
2. The coupling assembly of claim 1, wherein the coupler and the conduit are made of a material selected from the group consisting of: polyolefins and PVC.
3. The coupling assembly of claim 2 wherein the conduit is made of high density polyethylene.
4. The coupling assembly of claim 2 wherein the conduit is made of a material selected from the group consisting of: polyolefins and PVC.
5. The coupling assembly of claim 1, wherein the locking key is made of a polyamide.
6. The coupling assembly of claim 1, wherein the acute angle of coupler key groove faces at least partially along the axis of the coupler toward the opening at its end and the acute angle of the locking key fits into the acute angle of the coupler.
7. The coupling assembly of claim 6, wherein the acute angle of the conduit key groove faces at least partially along the axis of the conduit in a direction generally opposite the acute angle in the coupler key groove whereby axial forces trying to separate the coupler and the conduit cause the compression of locking key into the acute angle of the conduit key groove.
8. The coupling assembly of claim 7, wherein the coupler has a sealing groove along the circumference of the inner wall of the coupler.
9. The coupling assembly of claim 7, wherein a sealing groove is spaced axially between the abutment and the coupler key groove and a sealing ring is located in the sealing groove.
10. The coupling assembly of claim 1, wherein the coupler has a second opening at its other end and a second coupler key groove with an acute angle.
11. The coupling assembly of claim 1 wherein at least one acute angle of the locking key is smaller than the acute angle of the passageway it engages.
12. A coupler, comprising:
a locking key having a parallelogram shaped cross section with acute angles;
a coupler body having a generally cylindrical shape and a first opening at one end, the coupler body having an inner wall with an inner circumference and an outer wall;
a coupler key groove extending along the inner circumference of the inner wall of the coupler body, a portion of the coupler key groove forming part of a complimentary parallelogram with a complimentary acute angle with the locking key, the coupler key groove being located axially away from the opening in the coupler body;
an aperture connecting the coupler key groove with the outer wall of the coupler in order that the locking key can be inserted therein;
wherein at least one acute angle of the locking key is greater or less than the complementary acute angle of the coupler body key groove so that the at least one acute angle of the locking key engages tightly with the complementary acute angle of the coupler key groove when the coupler assembly is engaged with a conduit key groove.
13. The coupler of claim 12, wherein there is an abutment extending from the inner wall of the coupler body to limit the extent to which a conduit may be extended into the coupler body.
14. The coupler of claim 13, wherein the coupler body has a second opening at a second end and a second coupler key groove spaced from the second opening, the second coupler key groove having a portion thereof being an acute angle.
15. The coupler of claim 14, wherein there is at least one sealing groove along the inner circumference of the inner wall of the coupler body.
16. The coupler of claim 14, wherein the second coupler key groove is shaped in part like a parallelogram.
17. The coupler of claim 14 wherein the coupler is made of high density polyethylene.
18. The coupler of claim 12 wherein at least one of the acute angles of the locking key is smaller than the acute angle of the passageway it engages.
19. A coupling assembly comprising;
a coupler body having a generally cylindrical shape and an opening at one end, the coupler body having an inner wall and an outer wall;
a conduit having a generally cylindrical shape complementary to the coupler body, the conduit having an inner wall and an outer wall with an opening at its end, the conduit having dimensions and shape so that it fits snugly with the coupler body;
a coupler key groove extending along the circumference of one of the walls of the coupler body, the coupler key groove being located axially away from the opening in the coupler body;
a conduit key groove extending along the circumference of one of the walls of the conduit, the conduit key groove having a shape that is complementary to the coupler key groove;
a locking key that is complementary with the coupler key groove;
the coupler key groove and conduit key groove when they are aligned, form a parallelogram with acute angles and the locking key has a cross section of a complementary parallelogram with acute angles which fits therein, each acute angle of the locking key being greater or less than the complementary acute angle of the coupler body key groove and the conduit key groove so that the acute angles of the locking key tend to engage tightly the coupler key groove and the conduit key groove if tensile forces are applied to separate the coupler and the conduit.
20. The coupling assembly of claim 19, wherein the coupler and the conduit are made of a material selected from the group consisting of: polyolefins and PVC.
21. The coupling assembly of claim 19, wherein there is an abutment extending from the coupler body or the conduit to limit the extent to which the coupler body may overlap with a conduit.
22. The coupling assembly of claim 19 wherein at least one of the acute angles of the locking key is smaller than the acute angle of the passageway it engages.