| Summary: | 碩士 === 國立臺灣科技大學 === 資訊工程系 === 101 === This thesis addresses the problem of monitoring the k path nearest neighbours with respect to a continuously moving user approaching his destination in context of a road network. Given a destination where a user is going to, a new query returns the k-NN with respect to the shortest path connecting the destination and the user’s current location, and thus provides a list of nearest candidates for reference by considering the whole coming journey. This query is called as the k-Path Nearest Neighbour query (k-PNN). There is a need for continuous monitoring of the initial obtained k-NN solution since the user is continuously moving towards his destination and the previously obtained solution set could dynamically change with time. The challenge of monitoring the k-PNN for a moving user is to dynamically determine the update locations and then refresh the k-PNN efficiently. We follow a similar path as presented in [11] where a three-phase Best-first Network Expansion (BNE) algorithm is proposed. In the searching phase, the BNE finds the shortest path to the destination, during which a candidate set that guarantees to include the k-PNN is generated at the same time. Then in the verification phase, a heuristic algorithm runs for examining candidates’ and exact distances to the query path. Finally, the monitoring phase deals with computing update locations as well as refreshing the k-PNN based on the user’s position. Since monitoring is an expensive and resource consuming process, our work predominantly focuses on making the entire monitoring process more efficient and resource efficient, while maintaining the same level of accuracy. We present a novel approach for managing the update locations which could not only make the monitoring efficient but also decrease the total process time. Finally, we conduct extensive experiments on real road networks and compare our methods with the existing similar work and show that our method achieve satisfactory performance across various parameters.
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