Mapping the intellectual Structure in the field of Cultural Heritage Conservation: Co-occurrence Analysis

Abstract
Purpose: The purpose of present research is to map intellectual structure of the subject categories of Cultural Heritage Conservation articles indexed in AATA online database.
Methodology: This applied research has been done by clustering and Co-occurrence Analysis. The research statistical population includes all subject categories of articles indexed in the AATA database during 1800-2020. In order to perform hierarchical clustering, "Ward" method was used. Excel and SPSS software were used for data analysis. VOSviewer, UCINET and RavarPrimap software were used to visualization the co-occurrence network of topics.
Findings: The results revealed that the subject of "architectural conservation" was the most frequent subject. The "pigments, colors and paintings", "archaeological conservation" and "preventive conservation, and general topics" are topics were ranked second to fourth with the frequency of 15517, 14063, and 11518, respectively. The pair "Architecture Protection**Stone and related construction materials" has been the most common themes in terms of co-occurrence. Also, the pairs of "Archaeological Conservation** Ceramics, Glass and Glaze" and "Archaeological Conservation** Metals and Metallurgical Byproducts" were ranked the second and the third with 2099 and 273 repetitions, respectively. Hierarchical clustering, using the "Ward" method, resulted in formation of 8 thematic clusters. The cluster of "Studies focused on the type of protected material", included 49 topics, was the largest cluster. Other clusters were respectively: "theories and history" included 8 topics, "knowledge of techniques and materials and evaluation of treatment methods" included 26 subjects, "emergency Restoration and Risk Analysis" cluster included 20 topics, "Archaeological Conservation and Conservation Studies of Egypt" included 15 topics, "pathology and conservation of earthen architecture" cluster included 14 topics, "Historical Concrete (Sarouj)" cluster included 5 topics, "Historical Conservation Resources" included 5 topics.
Conclusion: "Architectural Conservation", "Pigments, Paints and Paintings", "Archaeological Conservation" and "Preventive Conservation" were among the topics of interest in the field of cultural heritage conservation. The results of the Co-occurrence analysis showed that the clusters of "Identification techniques and materials and evaluation of treatment methods" and "Historic Conservation Resources" were considered to be central, mature and well developed. These clusters have been played central role in cultural Heritage Conservation researches. The Clusters of "Archaeological Conservation and Conservation Studies of Egypt" and "Pathology and Conservation of Earthen Architecture" were not central, but considered as well developed clusters. Although these clusters, "Studies focused on the type of protected materials" and "Emergency conservation and risk assessment", had central role in cultural heritage conservation researches, they were immature. "Theories and History" and "Historical Concrete" clusters received less attention in researches.
The results of mapping the intellectual Structure using the co-occurrence analysis showed that the highest centrality degree was assigned to thematic categories of "Archaeological Conservation", "Pigments, Paints and Paintings" and "Architectural Conservation". This means that these subject areas had the most influence in the mentioned map. As a result, the mentioned areas were considered so important in the thematic structure of the field of cultural heritage conservation. Betweenness centrality also expresses the importance of the node in terms of its position on the map and in terms of information transmission in the network. Based on the obtained results, the subject categories with the most centrality were "metals and metallurgical products", "preventive protection and general issues" and "non-cellular natural organic materials (resins, varnish, wax, gum, oils...)". As a result, these thematic categories had an important and significant role in the transmission of information in the thematic network of cultural heritage conservation. On the other hand, the centrality index of the issues in the field of cultural heritage conservation were very close. This result shows that different topics have close influence power in the network.