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Your search keyword '"Cai, Zhongliang"' showing total 145 results
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145 results on '"Cai, Zhongliang"'

25. An improved hidden Markov model-based map matching algorithm considering candidate point grouping and trajectory connectivity.

Author

Li, Bozhao, Cai, Zhongliang, Kang, Mengjun, Su, Shiliang, Jiang, Lili, Ge, Yong, and Niu, Yanfen

Subjects
*ALGORITHMS, *VITERBI decoding, *HIDDEN Markov models, *POINT set theory, *PROBABILITY theory
Abstract

The hidden Markov model-based map matching algorithm (HMM-MM) is an effective method for online vehicle navigation and offline trajectory position correction. Common HMM-MMs are susceptible to the influence of adjacent road segment endpoints and similar parallel roads, because the multi-index probability model may ignore some indexes when the probability of other indexes is high. This makes the map-matching result not meet the assumption that vehicles always travel the shortest or optimal path, and it cannot guarantee that the trajectory points can match to the nearest position of the maximum likelihood road segment, resulting in poor accuracy. In this paper, an IHMM-MM is proposed. IHMM-MM (1) modifies the definition of transition probability and no longer takes the straight-line distance between trajectory points as the reference for the shortest path length between candidate point pairs. (2) supplements the definition of observation probability and introduces the point-line relation function to screen and group candidate points. (3) adds additional logic outside the HMM probability model to consider the trajectory connectivity and fill in the key trajectory points where the vehicles travel. Experiments show that the IHMM-MM can effectively improve the sampling frequency of trajectory data and has better performance in complex urban road environments. [ABSTRACT FROM AUTHOR]

Published
2023
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26. Pd-Catalyzed Coupling of Thioamides with N-Tosylhydrazones/Trapping by Esters Cascade Reaction

Author

Liqin Jiang, Cai Zhongliang, and Yao Zhi

Subjects
Chemistry, Organic Chemistry, Migratory insertion, chemistry.chemical_element, Trapping, Photochemistry, Biochemistry, Catalysis, Coupling (electronics), chemistry.chemical_compound, Cascade reaction, Physical and Theoretical Chemistry, Carbene, Palladium
Abstract

N,N-Disubstituted thioamides coupled with N-tosylhydrazones under Pd(TFA)2/tBuXPhos catalyst and NaOtBu, and the intermediates from palladium carbene migratory insertion containing β-hydrogen were ...

Published
2021
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28. Cobalt-Catalyzed Switchable Intramolecular Thioenolization/C–H Thiolation and C(sp2)–H/C(sp3)–H Dehydrogenative Coupling

Author

Zhen Long, Cai Zhongliang, Yao Zhi, and Liqin Jiang

Subjects
Coupling, Chemistry, Intramolecular force, Organic Chemistry, Polymer chemistry, Regioselectivity, chemistry.chemical_element, Physical and Theoretical Chemistry, Biochemistry, Cobalt, Catalysis
Abstract

Mild cobalt-catalyzed switchable regioselective and chemoselective thioenolization/C–H thiolation and C(sp2)–H/C(sp3)–H dehydrogenative couplings of N-aryl-N-alkyl-thioamides are developed, providi...

Published
2020
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39. A trajectory restoration algorithm for low-sampling-rate floating car data and complex urban road networks.

Author

Li, Bozhao, Cai, Zhongliang, Kang, Mengjun, Su, Shiliang, Zhang, Shanshan, Jiang, Lili, and Ge, Yong

Subjects
*AUTOMOBILES, *ALGORITHMS, *TOPOLOGY, *CONTINUITY, *GEOMETRY
Abstract

Low-sampling-rate floating car data (FCD) are more challenging than those with high-sampling-rate FCD for map matching (MM) algorithms. Some MM algorithms for low-sampling-rate FCD lack sufficient efficiency nor accuracy, especially related to complex urban road networks. This paper proposes a new method named the trajectory restoration algorithm, which is based on geometry MM algorithms to ensure efficiency and accuracy. The proposed algorithm adopts the modified A* shortest path algorithm to reduce the number of function calls and fully considers road network topology and historical matched points to improve its accuracy. We test the efficiency and accuracy of the trajectory restoration algorithm with FCD data for the complex urban road networks in Beijing. The results have strong continuity which greatly improves the utilization of FCD. We show that the proposed algorithm outperforms related MM methods in efficiency and accuracy and its robustness to restore trajectories of both high and low sampling rates in complex urban road networks. [ABSTRACT FROM AUTHOR]

Published
2021
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44. Interactive generalization on large-scale topographical map supported by a database platform

Author

Wu Hehal, Du Qingyun, Liao Chujiang, and Cai Zhongliang

Subjects
Data platform, Cartographic generalization, Database, Generalization, Computer science, Geography, Planning and Development, Data mining, Computers in Earth Sciences, computer.software_genre, Scale (map), Topographic map, computer
Abstract

This paper makes a study on the interactive digital generalization, where map generalization can be divided into intellective reasoning procedure and operational procedure, which are done by human and computer, respectively. And an interactive map generalization environment for large scale topographic map is then designed and realized. This research focuses on: ¹ the significance of researching an interactive map generalization environment, ² the features of large scale topographic map and interactive map generalization, ³ the construction of map generalization-oriented database platform.

Published
2003
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45. Integration and sharing of geo-spatial data based on data engine

Author

Wu Xiaofang, Cai Zhongliang, Du Qingyun, and Wu Guofeng

Subjects
Database, Computer science, Spatial database, Geography, Planning and Development, InformationSystems_DATABASEMANAGEMENT, computer.software_genre, Database design, Data modeling, Data sharing, Geo spatial, Relational database management system, Data model, Data mining, Computers in Earth Sciences, computer
Abstract

Through analyzing the principle of data sharing in the database system, this paper discusses the principle and method for integrating and sharing GIS data by data engine, introduces a way to achieve the high integration and sharing of GIS data on the basis of VCT in VC++, and provides the method for uniting VCT into RDBMS in order to implement a spatial database with object-oriented data model.

Published
2003
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46. The organization of multimedia information in electronic map

Author

Du Qingyun, Weng Min, Cai Zhongliang, and Wu Guofeng

Subjects
Information retrieval, Multimedia, Basis (linear algebra), Computer science, Geography, Planning and Development, Hypermedia, computer.software_genre, law.invention, Data model, law, Multimedia information, Electronic map, Computers in Earth Sciences, computer
Abstract

On the basis of an electronic map-based hypermedia data model (EMBHDM), this paper makes a study on the technologies of nonlinear storage, organization, management and browsing of information as well as organization of data on the basis of the relationship between multimedia information of electronic maps. This paper first analyzes some features of electronic maps and hypermedia technology, and then illustrates the creation of EMBHDM with some examples. The tests show that this model can efficiently organize and express multimedia data.

Published
2002
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