Nikolaos Papadakis

Prof. Dr. Nikolaos Papadakis


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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1 June 2020 in Logistics
Verified
Journal Article
Open access
PDF file
NBNikolaos Bakalos
Nikolaos Bakalos
NPNikolaos Papadakis
Nikolaos Papadakis
Antonios LitkeAntonios Litke
Antonios Litke
The purpose of this article is to present a framework for capturing and analyzing social media posts using a sentiment analysis tool to determine the views of the general public towards autonomous mobility. The paper presents the systems used and the results of this analysis, which was performed on social media posts from Twitter and Reddit. To achieve this, a specialized lexicon of terms was used to query social media content from the dedicated application programming interfaces (APIs) that the aforementioned social media platforms provide. The captured posts were then analyzed using a sentiment analysis framework, developed using state-of-the-art deep machine learning (ML) models. This framework provides labeling for the captured posts based on their content (i.e., classifies them as positive or negative opinions). The results of this classification were used to identify fears and autonomous mobility aspects that affect negative opinions. This method can provide a more realistic view of the general public’s perception of automated mobility, as it has the ability to analyze thousands of opinions and encapsulate the users’ opinion in a semi-automated way.

8 September 2024 in Sensors
Verified
Journal Article
Open access
PDF file
AKAthanasios Koulianos
Athanasios Koulianos
ΧΠΧρηστος Παρασκευόπουλος
Χρηστος Παρασκευόπουλος
Antonios LitkeAntonios Litke
Antonios Litke
NPNikolaos Papadakis
Nikolaos Papadakis
UAVs are increasingly being used in various domains, from personal and commercial applications to military operations. Ensuring the security and trustworthiness of UAV communications is crucial, and blockchain technology has been explored as a solution. However, privacy remains a challenge, especially in public blockchains. In this work, we propose a novel approach utilizing zero-knowledge proof techniques, specifically zk-SNARKs, which are non-interactive cryptographic proofs. This approach allows UAVs to prove their authenticity or location without disclosing sensitive information. We generated zk-SNARK proofs using the Zokrates tool on a Raspberry Pi, simulating a drone environment, and analyzed power consumption and CPU utilization. The results are promising, especially in the case of larger drones with higher battery capacities. Ethereum was chosen as the public blockchain platform, with smart contracts developed in Solidity and tested on the Sepolia testnet using Remix IDE. This novel proposed approach paves the way for a new path of research in the UAV area.

13 August 2020 in Applied Sciences
Verified
Journal Article
Open access
PDF file
DPDimitris Papadopoulos
Dimitris Papadopoulos
NPNikolaos Papadakis
Nikolaos Papadakis
Antonios LitkeAntonios Litke
Antonios Litke
The usefulness of automated information extraction tools in generating structured knowledge from unstructured and semi-structured machine-readable documents is limited by challenges related to the variety and intricacy of the targeted entities, the complex linguistic features of heterogeneous corpora, and the computational availability for readily scaling to large amounts of text. In this paper, we argue that the redundancy and ambiguity of subject–predicate–object (SPO) triples in open information extraction systems has to be treated as an equally important step in order to ensure the quality and preciseness of generated triples. To this end, we propose a pipeline approach for information extraction from large corpora, encompassing a series of natural language processing tasks. Our methodology consists of four steps: i. in-place coreference resolution, ii. extractive text summarization, iii. parallel triple extraction, and iv. entity enrichment and graph representation. We manifest our methodology on a large medical dataset (CORD-19), relying on state-of-the-art tools to fulfil the aforementioned steps and extract triples that are subsequently mapped to a comprehensive ontology of biomedical concepts. We evaluate the effectiveness of our information extraction method by comparing it in terms of precision, recall, and F1-score with state-of-the-art OIE engines and demonstrate its capabilities on a set of data exploration tasks.

6 July 2021
Verified
Conference Paper
Open access
GVGiannis Vassiliou
Giannis Vassiliou
GTGeorgia Troullinou
Georgia Troullinou
NPNikolaos Papadakis
Nikolaos Papadakis
Haridimos KondylakisHaridimos Kondylakis
Haridimos Kondylakis
Semantic summaries try to extract compact information from the original RDF graph, while reducing its size. State of the art structural semantic summaries, focus primarily on the graph structure of the data, trying to maximize the summary’s utility for a specific purpose, such as indexing, query answering and source selection. In this paper, we present an approach that is able to construct high quality summaries, exploiting a small part of the query workload, maximizing their utility for query answering, i.e. the query coverage. We demonstrate our approach using two real world datasets and the corresponding query workloads and we show that we strictly dominates current state of the art in terms of query coverage.

12 March 2024
Verified
Book Chapter
Closed access
PDF file
DGDimitrios Giagkos
Dimitrios Giagkos
OKOrestis Kompougias
Orestis Kompougias
Antonios LitkeAntonios Litke
Antonios Litke
NPNikolaos Papadakis
Nikolaos Papadakis

26 June 2024
Verified
Conference Paper
Open access
AIAndreas Ioannidis
Andreas Ioannidis
Antonios LitkeAntonios Litke
Antonios Litke
NPNikolaos Papadakis
Nikolaos Papadakis
In this paper we reconsider the classical concept of Randomized Response and investigate how it relates with data privacy and especially Differential Privacy. Our purpose is to formalize Randomized Response in a natural probability theoretic setting and investigate its statistical features from a mathematical point of view. More precisely, we propose a solid probabilistic framework which can be easily generalized to more complex cases. The analysis of the proposed framework shows its flexibility to be applied as a suitable differential privacy solution of sharing medical data over distributed cloud infrastructures.