Search

Video lectures are considered as one of the primary media to cater good-quality educational content to the learners. The video lectures illustrate the course-relevant concepts with necessary details. However, they sometimes fail to offer a basic understanding of off-topic concepts. Such off-topic concepts may spawn cognitive overload among the learners if those concepts are not familiar to them. To address this issue, we present a video lecture augmentation system that identifies the off-topic concepts and links them to relevant video lecture segments to furnish a basic understanding of the concerned concepts. Our augmentation system segregated the video lectures by identifying topical shifts in the lectures using a word embedding-based technique. The video segments were indexed on the basis of the underlying concepts. Identification of off-topic concepts was performed by modeling inter-concept relations in a semantic space. For each off-topic concept, appropriate video segments were fetched and re-ranked such that the top-ranked video segment offers the most basic understanding of the target off-topic concept. The proposed augmentation system was deployed as a web-based learning platform. Performance of the constituent modules was measured by using a manually curated dataset consisting of six video courses from the National Programme on Technology Enhanced Learning (NPTEL) archive. Feedback from 12 research scholars was considered to assess the quality of augmentations and usability of the learning platform. Both system and human-based evaluation indicated that the recommended augmentations were able to offer a basic understanding of the concerned off-topic concepts.

In this paper, we studied different automatic short answer grading (ASAG) systems to provide a comprehensive view of the feature spaces explored by previous works. While the performance reported in previous works have been encouraging, systematic study of the features is lacking. Apart from providing systematic feature space exploration, we also presented ensemble methods that have been experimentally validated to exhibit significantly higher grading performance over the existing papers in almost all the datasets in ASAG domain. A comparative study over different features and regression models toward short-answer grading has been performed with respect to evaluation metrics used in evaluating ASAG. Apart from traditional text similarity based features like WordNet similarity, latent semantic analysis, and others, we have introduced novel features like "topic models" suited for short text, "relevance feedback" based features. An ensemble-based model has been built using a combination of different regression models with an approach based on "stacked regression". The proposed ASAG has been tested on the University of North Texas dataset for the regression task, whereas in case of classification task, the student response analysis (SRA) based ScientsBank and Beetle corpus have been used for evaluation. The grading performance in case of ensemble-based ASAG is highly boosted from that exhibited by an individual regression model. Extensive experimentation has revealed that feature selection, introduction of novel features, and regressor stacking have been instrumental in achieving considerable improvement in performance over the existing methods in ASAG domain.

Author names in bibliographic databases often suffer from ambiguity owing to the same author appearing under different names and multiple authors possessing similar names. It creates difficulty in associating a scholarly work with the person who wrote it, thereby introducing inaccuracy in credit attribution, bibliometric analysis, search-by-author in a digital library and expert discovery. A plethora of techniques for disambiguation of author names has been proposed in the literature. In this article, we focus on the research efforts targeted to disambiguate author names specifically in the PubMed bibliographic database. We believe this concentrated review will be useful to the research community because it discusses techniques applied to a very large real database that is actively used worldwide. We make a comprehensive survey of the existing author name disambiguation (AND) approaches that have been applied to the PubMed database: we organise the approaches into a taxonomy; describe the major characteristics of each approach including its performance, strengths, and limitations; and perform a comparative analysis of them. We also identify the datasets from PubMed that are publicly available for researchers to evaluate AND algorithms. Finally, we outline a few directions for future work. [ABSTRACT FROM AUTHOR]

In this article, a pseudo-relevance feedback (PRF)–based framework is presented for effective query expansion (QE). As candidate expansion terms, the proposed PRF framework considers the terms that are different morphological variants of the original query terms and are semantically close to them. This strategy of selecting expansion terms is expected to preserve the query intent after expansion. While judging the suitability of an expansion term with respect to a base query, two aspects of relation of the term with the query are considered. The first aspect probes to what extent the candidate term is semantically linked to the original query and the second one checks the extent to which the candidate term can supplement the base query terms. The semantic relationship between a query and expansion terms is modelled using bidirectional encoder representations from transformers (BERT). The degree of similarity is used to estimate the relative importance of the expansion terms with respect to the query. The quantified relative importance is used to assign weights of the expansion terms in the final query. Finally, the expansion terms are grouped into semantic clusters to strengthen the original query intent. A set of experiments was performed on three different Text REtrieval Conference (TREC) collections to experimentally validate the effectiveness of the proposed QE algorithm. The results show that the proposed QE approach yields competitive retrieval effectiveness over the existing state-of-the-art PRF methods in terms of the mean average precision (MAP) and precision P at position 10 (P@10). [ABSTRACT FROM AUTHOR]