Nikolaos V. Boulgouris

Dr. Nikolaos V. Boulgouris


Research Focus & Metrics

Academic Career Length

15Years (2012-Present)

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

Representative Publications

View All Publications
12 June 2025 in IEEE Journal of Selected Topics in Signal Processing
Verified
Journal Article
Open access
BMBen Malin
Ben Malin
TKTatiana Kalganova
Tatiana Kalganova
NBNikolaos V. Boulgouris
Nikolaos V. Boulgouris
This review examines the means with which faithfulness has been evaluated across open-ended summarization, question answering and machine translation tasks. We find that the use of Large Language Models (LLMs) as a faithfulness evaluator is commonly the metric that is most highly correlated with human judgement. The means with which other studies have mitigated hallucinations is discussed, with both retrieval augmented generation (RAG) and prompting framework approaches having been linked with superior faithfulness, whilst other recommendations for mitigation are provided. Research into faithfulness is integral to the continued widespread use of LLMs, as unfaithful responses can pose major risks to many areas whereby LLMs would otherwise be suitable. Furthermore, evaluating open-ended generation provides a more comprehensive measure of LLM performance than commonly used multiplechoice benchmarking, which can help in advancing the trust that can be placed within LLMs.

7 June 2013 in IEEE Transactions on Image Processing
Verified
Journal Article
Closed access
NBNikolaos V. Boulgouris
Nikolaos V. Boulgouris
XHXiaxi Huang
Xiaxi Huang
We propose a new gait recognition method that combines holistic and model-based features. Both types of features are extracted automatically from gait silhouette sequences and their combination takes place by means of a pair of hidden Markov models. In the proposed system, the holistic features are initially used for capturing general gait dynamics whereas, subsequently, the model-based features are deployed for capturing more detailed sub-dynamics by refining upon the preceding general dynamics. Furthermore, the holistic and model-based features are suitably processed in order to improve the discriminatory capacity of the final system. The experimental results show that the proposed method exhibits performance advantages in comparison with popular existing methods.

5 October 2022 in IEEE Transactions on Neural Networks and Learning Systems
Verified
Journal Article
Closed access
PWPingyu Wang
Pingyu Wang
FSFei Su
Fei Su
ZZZhicheng Zhao
Zhicheng Zhao
YZYanyun Zhao
Yanyun Zhao
NBNikolaos V. Boulgouris
Nikolaos V. Boulgouris
As person parts are frequently misaligned between detected human boxes, an image representation that can handle this part misalignment is required. In this work, we propose an effective grouped attentive re-identification (GAReID) framework to learn part-aligned and background robust representations for person re-identification (ReID). Specifically, the GAReID framework consists of grouped high-order pooling (GHOP) and attentive high-order pooling (AHOP) layers, which generate high-order image and foreground features, respectively. In addition, a novel grouped Kronecker product (GKP) is proposed to use both channel group and shuffle strategies for high-order feature compression, while promoting the representational capabilities of compressed high-order features. We show that our method derives from an interpretable motivation and elegantly reduces part misalignments without using landmark detection or feature partition. This article theoretically and experimentally demonstrates the superiority of the GAReID framework, achieving state-of-the-art performance on various person ReID datasets.

22 June 2022 in Applied Sciences
Verified
Journal Article
Open access
PDF file
NHNauman Hafeez
Nauman Hafeez
XDXinli Du
Xinli Du
NBNikolaos V. Boulgouris
Nikolaos V. Boulgouris
PBPhilip Begg
Philip Begg
RIRichard Irving
Richard Irving
GTGuillaume TOURREL
Guillaume TOURREL
Cochlear implants provide hearing perception to people with severe to profound hearing loss. The electrode array (EA) inserted during the surgery directly stimulates the hearing nerve, bypassing the acoustic hearing system. The complications during the EA insertion in the inner ear may cause trauma leading to infection, residual hearing loss, and poor speech perception. This work aims to reduce the trauma induced during electrode array insertion process by carefully designing a sensing method, an actuation system, and data-driven control strategy to guide electrode array in scala tympani. Due to limited intra-operative feedback during the insertion process, complex bipolar electrical impedance is used as a sensing element to guide EA in real time. An automated actuation system with three degrees of freedom was used along with a complex impedance meter to record impedance of consecutive electrodes. Prediction of EA direction (medial, middle, and lateral) was carried out by an ensemble of random forest, shallow neural network, and k-nearest neighbour in an offline setting with an accuracy of 86.86%. The trained ensemble was then utilized in vitro for prediction and correction of EA direction in real time in the straight path with an accuracy of 80%. Such a real-time system also has application in other electrode implants and needle and catheter insertion guidance.


30 May 2024 in IEEE Transactions on Medical Robotics and Bionics
Verified
Journal Article
Closed access
NHNauman Hafeez
Nauman Hafeez
NBNikolaos V. Boulgouris
Nikolaos V. Boulgouris
PBPhilip Begg
Philip Begg
RIRichard Irving
Richard Irving
CCChris Coulson
Chris Coulson
XDXinli Du
Xinli Du
Cochlear implants have significantly improved hearing for many as the most successful prosthesis, however, hearing outcomes vary. Uncertainty during electrode array (EA) insertion, including trauma and depth control, is one factor. To minimize radiation exposure from imaging methods like CT scans, this in-vitro study investigates the use of bipolar electrode impedance and artificial intelligent models to determine EA insertion depth. Complex impedance data was collected by inserting a commercial EA into a scaled-up 2D scala tympani model using a robotic feeder system. A support vector machine model produced a 98% classification accuracy for final insertion depth estimation. A CNN-LSTM hybrid model yielded 0.85 R-squared and 1.72 mm mean absolute error in depth estimation at each millimeter during a 25 mm insertion. This approach to depth assessment based on impedance may help with cochlear implant procedures and find use in other medical implant applications.