1. An ultrathin tellurium nanowire structure, comprising:
a rod-like crystalline structure of tellurium, wherein the crystalline structure is defined by diameters of between 5-6 nm.
2. The ultrathin tellurium nanowire structure of claim 1, wherein the crystalline structure is prepared by a process comprising the steps of:
(a) mixing an amount of polyvinylpyrrolidone, an amount of an alkali, and an amount of one of tellurium dioxide and telluride salt to generate a first solution;
(b) dissolving the first solution in ethylene glycol to generate a second mixture;
(c) heating the second mixture; and
(d) mixing an amount of hydrazine hydrate with the second mixture to generate a third mixture containing the rod-like crystalline structure of tellurium.
3. The ultrathin tellurium nanowire structure of claim 2, wherein the amount of polyvinylpyrrolidone is about 0.1 to 1.0 g.
4. The ultrathin tellurium nanowire structure of claim 3, wherein the amount of alkali is about 0.2 to 0.8 g.
5. The ultrathin tellurium nanowire structure of claim 4, wherein the alkali is one of sodium hydroxide and potassium hydroxide.
6. The ultrathin tellurium nanowire structure of claim 5, wherein the tellurium salt is one of sodium tellurite, potassium tellurite, and tellurium dioxide.
7. The ultrathin tellurium nanowire structure of claim 6, wherein the second mixture is heated to about 100-180\xb0 C.
8. The ultrathin tellurium nanowire structure of claim 7, wherein the amount of hydrazine hydrate is about 0.2 to 1 ml.
9. An ultrathin tellurium-based nanowire structure, comprising:
a rod-like crystalline structure of one of lead telluride and bismuth telluride, wherein an ultrathin tellurium nanowire structure is used as a precursor to generate the rod-like crystalline structure.
10. The ultrathin tellurium-based nanowire structure of claim 9, wherein the lead telluride rod-like crystalline structure includes diameters between 9-10 nm and the bismuth telluride rod-like crystalline structures includes diameters between 7-8 nm.
11. The ultrathin tellurium-based nanowire structure of claim 10, wherein the precursor ultrathin nanowire includes diameters between 5-6 nm.
12. The ultrathin tellurium-based nanowire structure of claim 9, wherein the crystalline structure is prepared by a process comprising the step of:
injecting one of lead acetate tri-hydrate and bismuth nitrate penta-hydrate into an ethylene glycol precursor solution containing the ultrathin tellurium nanowire structures.
13. A nanoscale heterostructure tellurium-based nanowire structure, comprising:
a dumbbell-like crystalline heterostructure having a center rod-like portion and one octahedral structure connected to each end of each of the center rod-like portions, wherein the center rod-like portion is a tellurium nanowire structure and the octahedral structures are one of lead telluride, cadmium telluride, and bismuth telluride.
14. The nanoscale heterostructure tellurium-based nanowire structure of claim 13, wherein the center rod-like portion is defined by a diameter of about 20 nm.
15. The nanoscale heterostructure tellurium-based nanowire structure of claim 14, wherein edge length of the lead telluride is about 65 nm.
16. The nanoscale heterostructure tellurium-based nanowire structure of claim 15, wherein diameter of the cadmium telluride octahedral structure is about 30 nm.
17. The nanoscale heterostructure tellurium-based nanowire structure of claim 13, wherein the dumbbell-like crystalline structure is prepared by a process comprising the steps of:
(a) preparing a lead precursor solution; and
(b) injecting the lead precursor solution into an ethylene glycol precursor solution containing the tellurium-based nanowire structures.
18. The nanoscale heterostructure tellurium-based nanowire structure of claim 17, wherein the lead precursor is prepared by dissolving one of Pb(CH3COO)23H2O and Pb(NO3)23H2O into ethylene glycol.
19. The nanoscale heterostructure tellurium-based nanowire structure of claim 17, wherein the ethylene glycol precursor solution containing the tellurium-based nanowire structures is prepared by a process comprising the steps of:
(a) mixing an amount of polyvinylpyrrolidone, an amount of an alkali, and an amount of one of tellurium dioxide and telluride salt to generate a first solution;
(b) dissolving the first solution in ethylene glycol to generate a second mixture;
(c) heating the second mixture; and
(d) mixing an amount of hydrazine hydrate with the second mixture to generate the ethylene glycol precursor solution.
20. The nanoscale heterostructure tellurium-based nanowire structure of claim 19, wherein the molar ratio between one of Pb(CH3COO)23H2O and Pb(NO3)23H2O and tellurium dioxide is less than 1.
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 estimating a position of a wireless local area network (WLAN) enabled mobile device, comprising:
receiving, by the mobile device, one or more WLAN packets transmitted within a range of the mobile device;
extracting WLAN information from the one or more WLAN packets to identify one or more WLAN access points (APs);
based on the extracted WLAN information, caching information, at the mobile device, indicating an identity of the one or more WLAN APs and a time of detection of the one or more WLAN APs;
subsequent to the caching, receiving a request for a position estimate of the mobile device; and
in response to the subsequently-received request for the position estimate, providing the cached information to a WLAN positioning system (WPS) to obtain an estimate of the position of the mobile device that is based, at least in part, on one or more past positions of the mobile device indicated by the cached information.
2. The method of claim 1, wherein the extracted WLAN information includes a media access control (MAC) address of the one or more WLAN APs, and the caching maintains a list of MAC addresses of the one or more WLAN APs.
3. The method of claim 1, wherein the cached information maintains the identity of WLAN APs identified over a last given period of time.
4. The method of claim 1, wherein the cached information maintains the identity of most recently identified WLAN APs up to a maximum number of most recently identified WLAN APs.
5. The method of claim 1, wherein the receiving occurs when WLAN APs cannot be detected by the mobile device, and the providing obtains the estimated position of the mobile device in the absence of presently-detectable WLAN APs.
6. The method of claim 1, wherein the estimate of the position of the mobile device is based on a history of movement of the mobile device derived from the cached information.
7. The method of claim 1, wherein the receiving comprises sniffing one or more WLAN packets destined for one or more WLAN devices other than the mobile device.
8. The method of claim 1, wherein the receiving comprises sniffing one or more WLAN packets originated by the one or more WLAN APs.
9. The method of claim 1, wherein the receiving comprises sniffing one or more WLAN packets destined for the one or more WLAN APs.
10. The method of claim 1, wherein the WPS is resident, at least in part, on a server remote from the mobile device, and the providing comprises:
sending the cached information to the server.
11. The method of claim 1, wherein the WPS is resident, at least in part, on the mobile device.
12. The method of claim 1, wherein the one or more WLAN packets include broadcast packets.
13. The method of claim 1, wherein the extracting further comprises:
detecting at least one error in the one or more WLAN packets;
combining different packets with a measure of similarity that is above a threshold, to produce combined information; and
identifying the one or more WLAN APs based on the combined information.
14. A wireless local area network (WLAN) enabled mobile device operable to estimate a position, comprising:
a WLAN radio module configured to receive one or more WLAN packets transmitted within a range of the mobile device;
extraction logic configured to extract WLAN information from the one or more WLAN packets to identify one or more WLAN access points (APs);
a cache configured to maintain cached information indicating an identity of the one or more WLAN APs and a time of detection of the one or more WLAN APs; and
logic configured to, in response to a request for a position estimate of the mobile device, provide the cached information to a WLAN positioning system (WPS) to obtain an estimate of a position of the mobile device that is based, at least in part, on one or more past positions of the mobile device indicated by the cached information.
15. The mobile device of claim 14, wherein the extracted WLAN information includes a media access control (MAC) address of the one or more WLAN APs, and the cache maintains a list of MAC addresses of the one or more WLAN APs.
16. The mobile device of claim 14, wherein the cached information includes the identity of WLAN APs identified over a last given period of time.
17. The mobile device of claim 14, wherein the cached information includes the identity of most recently identified WLAN APs identified to a maximum number of most recently identified WLAN APs.
18. The mobile device of claim 14, wherein the logic is configured to provide the cached information to the WPS to obtain an estimate of a position of the mobile device in an absence of presently-detectable WLAN APs.
19. One or more non-transitory computer-readable media storing positioning software, the positioning software when executed on one or more processors operable to:
detect one or more wireless local area network (WLAN) packets transmitted within a range of a mobile device;
extract WLAN information from the one or more WLAN packets to identify one or more WLAN access points (APs);
based on the extracted WLAN information, cache information indicating an identity of the one or more WLAN APs;
use the cached information indicating the identity of the one or more WLAN APs to obtain an estimate of a position of the mobile device that is based, at least in part, on one or more past positions of the mobile device indicated by the cached information.
20. The one or more non-transitory computer-readable media of claim 19, wherein the extracted WLAN information includes a media access control (MAC) address of the one or more WLAN APs, and the cached information includes a list of MAC addresses of the one or more WLAN APs.
21. A method for estimating a position of a wireless local area network (WLAN) enabled mobile device, comprising:
receiving, by the mobile device, one or more WLAN packets transmitted within a range of the mobile device;
extracting WLAN information from the one or more WLAN packets to identify one or more WLAN access points (APs);
storing a history of detected WLAN APs, at the mobile device, indicating an identity of the one or more WLAN APs and a time of detection of the one or more WLAN APs; and
subsequent to the storing,
receiving a request for a position estimate of the mobile device from an application on the mobile device,
determining the mobile device cannot detect WLAN APs, and
using the history of detected WLAN APs to obtain the position estimate of the mobile device.
22. The method of claim 21, wherein the history of detected WLAN APs maintains the identity of WLAN APs identified over a last given period of time.
23. The method of claim 21, wherein the history of detected WLAN APs maintains the identity of most recently identified WLAN APs up to a maximum number of most recently identified WLAN APs.
24. A wireless local area network (WLAN) enabled mobile device operable to estimate a position, comprising:
a WLAN radio module configured to receive one or more WLAN packets transmitted within a range of the mobile device;
extraction logic configured to extract WLAN information from the one or more WLAN packets to identify one or more WLAN access points (APs);
a cache configured to maintain cached information indicating an identity of the one or more WLAN APs and a time of detection of the one or more WLAN APs; and
logic configured to, in response to a request for a position estimate of the mobile device received from an application on the mobile device, determine the mobile device cannot detect WLAN APs, and provide the history of detected WLAN APs to a WLAN positioning system (WPS) to obtain the position estimate of the mobile device.
25. The mobile device of claim 24, wherein the extracted WLAN information includes a media access control (MAC) address of the one or more WLAN APs, and the cache maintains a list of MAC addresses of the one or more WLAN APs.