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Addressing the issues of redundant exploration and inapplicability in dynamic environments inherent in fast marching tree algorithm (FMT), this paper proposed the APF-Dynamic FMT algorithm, which integrated artificial potential field method. This algorithm designed a sampling point guidance function based on artificial potential field method, which could dynamically adjust the sampling point generation range according to the environment information to reduce redundant exploration. Additionally, this algorithm designed a dynamic path tree adjustment mechanism, when the existing path was affected by the environment change, it could re-plan a new excellent path on the basis of the remaining path tree that is not affected, which was suitable for solving the path planning problem in dynamic environment. The results verify that the APF-Dynamic FMT algorithm can significantly improve the success rate and path quality of path planning while consuming the same computational resources, and when the existing path is affected by the dynamic environment, it can efficiently re-plan the passable excellent path. [ABSTRACT FROM AUTHOR]

Copyright of Journal of National University of Defense Technology / Guofang Keji Daxue Xuebao is the property of NUDT Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to address the problem of inability to parallelly identify multiple tags in the Improved Collision Tree（ICT） algorithm when there are multiple collision slots and collisions at multiple positions in large-scale tag scenarios,this paper developed a Parallel Identification Collision Tree（PICT） algorithm based on Walsh codes for RFID. The PICT algorithm combined Walsh synchronization orthogonal codes with the collision tree protocol. It used Walsh codes to spread the tags involved in multiple collisions in the ICT algorithm, and tags with unique Walsh codes communicate with the reader through different sub-channels, enabling parallel identification of multiple tags. Theoretical and experimental analyses demonstrated that the PICT algorithm requires fewer total system time slots compared to similar algorithms, and it achieves higher system identification efficiency, making it suitable for fast identification of largescale tags. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Geodesy & Geodynamics (1671-5942) is the property of Editorial Board Journal of Geodesy & Geodynamics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

When applying the LANDMARC algorithm based on RFID for vehicle location in an indoor parking lot, the accuracy of vehicle positioning cannot be improved by increasing the number of reference tags or deploying reference tags uniformly and regularly, because the complex structure of the indoor parking lot and the influence of multi-path effects of wireless. This paper proposed a location algorithm based on virtual tag (LAVT). The algorithm got the neighbor region of the vehicle through location of the nearest neighbor tags, to finding the center of the circumcircle and calculate the circumcenter of the neighbor region as the insertion point of the virtual tag. This paper replaced the original nearest neighbor tag with the virtual tag, to reduce the size of the neighbor region, and made the new nearest neighbor tag closer to the vehicle to be located, and to calculate the position vehicle more accurately. The simulation experiments and results show that LAVT improves the location accuracy by 19.03% compared to the traditional algorithm. The LAVT algorithm has better applicability for vehicle positioning in indoor parking lot environment, meeting the basic requirement of vehicle positioning in indoor parking lot. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Geodesy & Geodynamics (1671-5942) is the property of Editorial Board Journal of Geodesy & Geodynamics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrographic Surveying & Charting / Haiyang Cehui is the property of Hydrographic Surveying & Charting Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

On-board atomic clock as the key to maintain the time scale，its performance will affect the navigation，positioning and timing of the user's accuracy. The definition and calculation method of atomic clock frequency accuracy， drift and stability were introduced，using satellite clock error data provided by iGMAS，IGS and MGEX in the GNSS on-board atomic clocks performance assessment. And，on this basis we analyzed the characteristics of GNSS on-board atomic clocks. The results show that the rubidium clocks on GPS BLOCK IIF and the space borne hydrogen clocks in Galileo system have the best comprehensive performance; the day stability of BDS MEO and IGSO on-board atomic clocks have reached the level of 2〜4X 1 0—14，almost the same precision as the GPS BLOCK IIR satellites ; and the frequency accuracy reached the level of 1〜4 X10—11，and the frequency drift reached the level of 10—14. [ABSTRACT FROM AUTHOR]

Copyright of Geomatics & Information Science of Wuhan University is the property of Geomatics & Information Science of Wuhan University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Liquid Crystal & Displays is the property of Chinese Journal of Liquid Crystal & Displays and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)