Nikolaos Tsipas

Dr. Nikolaos Tsipas

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Research Focus & Metrics

Academic Career Length

10Years (2017-Present)

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

Representative Publications

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10 January 2017 in Multimedia Tools and Applications
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Journal Article
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NTNikolaos Tsipas
Nikolaos Tsipas
Lazaros VrysisLazaros Vrysis
Lazaros Vrysis
CDCharalampos Dimoulas
Charalampos Dimoulas
GPGeorge Papanikolaou
George Papanikolaou

25 July 2019 in Education Sciences
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Journal Article
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ECElena Chatzara
Elena Chatzara
Rigas KotsakisRigas Kotsakis
Rigas Kotsakis
NTNikolaos Tsipas
Nikolaos Tsipas
Lazaros VrysisLazaros Vrysis
Lazaros Vrysis
Charalampos DimoulasCharalampos Dimoulas
Charalampos Dimoulas
Art and technology have always been very tightly intertwined, presenting strong influences on each other. On the other hand, technological evolution led to today’s digital media landscape, elaborating mediated communication tools, thus providing new creative means of expression (i.e., new-media art). Rich-media interaction can expedite the whole process into an augmented schooling experience though art cannot be easily enclosed in classical teaching procedures. The current work focuses on the deployment of a modern-art web-guide, aiming at enhancing traditional approaches with machine-assisted blended-learning. In this perspective, “machine” has a two-folded goal: to offer highly-interdisciplinary multimedia services for both in-class demonstration and self-training support, and to crowdsource users’ feedback, as to train artificial intelligence systems on painting movements semantics. The paper presents the implementation of the “Istoriart” website through the main phases of Analysis, Design, Development, and Evaluation, while also answering typical questions regarding its impact on the targeted audience. Hence, elaborating on this constructive case study, initial hypotheses on the multidisciplinary usefulness, and contribution of the new digital services are put into test and verified.

11 April 2020 in Information
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Journal Article
Open access
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Nikolaos VryzasNikolaos Vryzas
Nikolaos Vryzas
NTNikolaos Tsipas
Nikolaos Tsipas
Charalampos DimoulasCharalampos Dimoulas
Charalampos Dimoulas
Radio is evolving in a changing digital media ecosystem. Audio-on-demand has shaped the landscape of big unstructured audio data available online. In this paper, a framework for knowledge extraction is introduced, to improve discoverability and enrichment of the provided content. A web application for live radio production and streaming is developed. The application offers typical live mixing and broadcasting functionality, while performing real-time annotation as a background process by logging user operation events. For the needs of a typical radio station, a supervised speaker classification model is trained for the recognition of 24 known speakers. The model is based on a convolutional neural network (CNN) architecture. Since not all speakers are known in radio shows, a CNN-based speaker diarization method is also proposed. The trained model is used for the extraction of fixed-size identity d-vectors. Several clustering algorithms are evaluated, having the d-vectors as input. The supervised speaker recognition model for 24 speakers scores an accuracy of 88.34%, while unsupervised speaker diarization scores a maximum accuracy of 87.22%, as tested on an audio file with speech segments from three unknown speakers. The results are considered encouraging regarding the applicability of the proposed methodology.

1 December 2020 in The Journal of the Acoustical Society of America
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Journal Article
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NTNikolaos Tsipas
Nikolaos Tsipas
Lazaros VrysisLazaros Vrysis
Lazaros Vrysis
KKKonstantinos Konstantoudakis
Konstantinos Konstantoudakis
Charalampos DimoulasCharalampos Dimoulas
Charalampos Dimoulas
In this paper, an audio-driven, multimodal approach for speaker diarization in multimedia content is introduced and evaluated. The proposed algorithm is based on semi-supervised clustering of audio-visual embeddings, generated using deep learning techniques. The two modes, audio and video, are separately addressed; a long short-term memory Siamese neural network is employed to produce embeddings from audio, whereas a pre-trained convolutional neural network is deployed to generate embeddings from two-dimensional blocks representing the faces of speakers detected in video frames. In both cases, the models are trained using cost functions that favor smaller spatial distances between samples from the same speaker and greater spatial distances between samples from different speakers. A fusion stage, based on hypotheses derived from the established practices in television content production, is deployed on top of the unimodal sub-components to improve speaker diarization performance. The proposed methodology is evaluated against VoxCeleb, a large-scale dataset with hundreds of available speakers and AVL-SD, a newly developed, publicly available dataset aiming at capturing the peculiarities of TV news content under different scenarios. In order to promote reproducible research and collaboration in the field, the implemented algorithm is provided as an open-source software package.

22 February 2020 in Social Sciences
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KPKosmas Panagiotidis
Kosmas Panagiotidis
NTNikolaos Tsipas
Nikolaos Tsipas
Theodora SaridouTheodora Saridou
Theodora Saridou
Andreas VeglisAndreas Veglis
Andreas Veglis
During the last two decades, citizens’ participation in news production process has attracted significant interest from both academia and the media industry. Media production and consumption have been altered considerably and traditional concepts, such as gatekeeping, have been under discussion. Many news organisations include in their websites tools and applications that allow users to be active consumers or even co-producers of journalistic content, by liking, sharing, commenting and submitting material. At the same time, large amounts of user-generated content are uploaded every day on social media platforms. Subsequently, media organisations must deal with continually available information which requires management, classification and evaluation not only to keep high journalistic standards, but also to avoid problems. The latter category can include grammar mistakes, fake or misleading information and hate speech. All the above-mentioned parameters highlight the obvious need for platforms that can support journalism manage practice. Such a platform should utilise semantic technologies, which can support organised collection and moderation of content in an effective way and in short time. This study discusses the design and the implementation of a participatory journalism management platform.

1 July 2018 in Signal Processing: Image Communication
Verified
Journal Article
Closed access
KKKonstantinos Konstantoudakis
Konstantinos Konstantoudakis
Lazaros VrysisLazaros Vrysis
Lazaros Vrysis
NTNikolaos Tsipas
Nikolaos Tsipas
Charalampos DimoulasCharalampos Dimoulas
Charalampos Dimoulas