Abstract: At present, focused crawler is a crucial method for obtaining effective domain knowledge from massive heterogeneous networks. For most current focused crawling technologies, there are some difficulties in obtaining high-quality crawling results. The main difficulties are the establishment of topic benchmark models, the assessment of topic relevance of hyperlinks, and the design of crawling strategies. In this paper, we use domain ontology to build a topic benchmark model for a specific topic, and propose a novel multiple-filtering strategy based on local ontology and global ontology (MFSLG). A comprehensive priority evaluation method (CPEM) based on the web text and link structure is introduced to improve the computation precision of topic relevance for unvisited hyperlinks, and a simulated annealing (SA) method is used to avoid the focused crawler falling into local optima of the search. By incorporating SA into the focused crawler with MFSLG and CPEM for the first time, two novel focused crawler strategies based on ontology and SA (FCOSA), including FCOSA with only global ontology (FCOSA_G) and FCOSA with both local ontology and global ontology (FCOSA_LG), are proposed to obtain topic-relevant webpages about rainstorm disasters from the network. Experimental results show that the proposed crawlers outperform the other focused crawling strategies on different performance metric indices.

Key words: Focused crawler; Ontology; Priority evaluation; Simulated annealing; Rainstorm disaster

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