Nikola Stoyanov Nikolov

Dr. Nikola Stoyanov Nikolov

orcid

Research Focus & Metrics

Academic Career Length

25Years (2002-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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27 August 2019 in Journal of Big Data
Verified
Journal Article
Open access
PDF file
KTKhawla Tadist
Khawla Tadist
SNSaid Najah
Said Najah
NNNikola Stoyanov Nikolov
Nikola Stoyanov Nikolov
FMFatiha Mrabti
Fatiha Mrabti
AZAzeddine Zahi
Azeddine Zahi
In the era of accelerating growth of genomic data, feature-selection techniques are believed to become a game changer that can help substantially reduce the complexity of the data, thus making it easier to analyze and translate it into useful information. It is expected that within the next decade, researchers will head towards analyzing the genomes of all living creatures making genomics the main generator of data. Feature selection techniques are believed to become a game changer that can help substantially reduce the complexity of genomic data, thus making it easier to analyze it and translating it into useful information. With the absence of a thorough investigation of the field, it is almost impossible for researchers to get an idea of how their work relates to existing studies as well as how it contributes to the research community. In this paper, we present a systematic and structured literature review of the feature-selection techniques used in studies related to big genomic data analytics.

1 January 2018 in Procedia Computer Science
Verified
Journal Article
Open access
AAAzalden Alakrot
Azalden Alakrot
LMLiam Murray
Liam Murray
NNNikola Stoyanov Nikolov
Nikola Stoyanov Nikolov

1 January 2018 in Procedia Computer Science
Verified
Journal Article
Open access
AAAzalden Alakrot
Azalden Alakrot
LMLiam Murray
Liam Murray
NNNikola Stoyanov Nikolov
Nikola Stoyanov Nikolov

1 October 2019
Verified
Conference Paper
Closed access
HMHanane Mohaouchane
Hanane Mohaouchane
AMAsmaa Mourhir
Asmaa Mourhir
NNNikola Stoyanov Nikolov
Nikola Stoyanov Nikolov
Offensive content on social media such as verbal attacks, demeaning comments or hate speech has many negative effects on its users. The automatic detection of offensive language on Arabic social media is an important step towards the regulation of such content for Arabic speaking users of social media. This paper presents the results of evaluating the performance of four different neural network architectures for this task: Convolutional Neural Network (CNN), Bidirectional Long Short-Term Memory (Bi-LSTM), Bi-LSTM with attention mechanism, and a combined CNN-LSTM architecture. These networks are trained and tested on a labeled dataset of Arabic YouTube comments. We run this dataset through a series of pre-processing steps and use Arabic word embeddings to represent the comments. We also apply Bayesian optimization techniques to tune the hyperparameters of the neural network models. We train and test each network using 5-fold cross validation. The CNN-LSTM achieves the highest recall (83.46%), followed by the CNN (82.24%), the Bi-LSTM with attention (81.51%) and the Bi-LSTM (80.97%).

20 April 2021 in IEEE Access
Verified
Journal Article
Open access
HZHaiyang Zhang
Haiyang Zhang
Ivan GanchevIvan Ganchev
Ivan Ganchev
NNNikola Stoyanov Nikolov
Nikola Stoyanov Nikolov
ZJZhanlin Ji
Zhanlin Ji
MOMairtin O'DRoma
Mairtin O'DRoma
Matrix Factorization (MF) is one of the most successful Collaborative Filtering (CF) techniques used in recommender systems due to its effectiveness and ability to deal with very large user-item rating matrix. However, when the rating matrix sparseness increases its performance deteriorates. Expanding MF to include side-information of users and items has been shown by many researchers both to improve general recommendation performance and to help alleviate the data-sparsity and cold-start issues in CF. In regard to item feature side-information, most schemes incorporate this information through a two stage process: intermediate results (e.g., on item similarity) are first computed based on item attributes; these are then combined with MF. In this paper, focussing on item side-information, we propose a model that directly incorporates item features into the MF framework in a single step process. The model, which we name FeatureMF, does this by projecting every available attribute datum in each of the item features into the same latent factor space with users and items, thereby in effect enriching item representation in MF. Results are presented of comparative performance experiments of the model against three state-of-the-art item information enriched models, as well as against four reference benchmark models, using two public real-world datasets, Douban and Yelp, with four training:test ratio scenarios each. It is shown to yield the best recommendation performance over all these models across all contexts including data-sparsity situations, in particular, achieving over 0.9% to over 6.5% MAE recommendation performance improvement over the next best model, HERec. FeatureMF is also found to alleviate cold start and to scale well, almost linearly, in regard to computational time, as a function of dataset size.

21 February 2002 in Lecture Notes in Computer Science
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Book Chapter
Closed access
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PHPatrick Healy
Patrick Healy
NNNikola Stoyanov Nikolov
Nikola Stoyanov Nikolov