Content area
Full text
Introduction
In our information society the internet has become the greatest human knowledge base ([30] Segev et al. , 2007). The volume of information published on the internet is growing rapidly, as are the number of users accessing the web. Many electronic libraries are playing a key role in allowing their information depositories to be accessed easily and efficiently via the internet.
However the performance of a centralised storage database for an electronic library may decrease as the size of the document collection and the number of users increase ([2] Basirat and Khan, 2010). In general different electronic libraries define different search criteria to access their own document collections. In addition users have to learn how to use the new search model for each of the various different online electronic libraries. Thus, in order to access several electronic libraries simultaneously, the integration of different distributed electronic libraries via a federated service that provides a unified interface for users is necessary ([41] Trnkoczy et al. , 2006).
In recent times grid and cloud technologies have provided a novel means for the sharing and coordinated use of diverse resources in dynamic, distributed and virtual organisations ([38] Stanoevska-Slabeva et al. , 2010). Even though there is no consensus on the difference between them, grid computing is treated as the foundation of cloud computing ([13] Foster et al. , 2008). Grid computing can support the integration of all distributed heterogeneous online databases in one platform and facilitate the discovery process easily and efficiently ([12] Foster et al. , 2001). However the current search mechanisms for use on the grid or cloud are mostly based on keyword matching ([45] Vega-Gorgojo et al. , 2005). The traditional keyword-based search mechanism retrieves documents with less relevance to the queries ([15] Haav and Lubi, 2001; [34] Sieg et al. , 2007). The main issue is that a keyword-based search model treats a term or a word only as a sequence of binary codes. It does not take into account the concept of the term and the relationship between terms as a cue for searching. Thus it involves word form mapping between queries and data resources in general. Even if some linguistic techniques, such as word stemming and removal of stop words are...