18480 research outputs found
Sort by
Self-Adaptive Colour Calibration of Deep Underwater Images Using FNN and SfM-MVS-Generated Depth Maps
No full textΗ παρούσα διδακτορική διατριβή αντιμετωπίζει την πρόκληση της εξασθένισης των χρωμάτων σε υποβρύχιες εικόνες μεγάλου βάθους που έχουν ληφθεί υπό τεχνητό φωτισμό. Αρχικά, η έρευνα στόχευε στη μοντελοποίηση και επίλυση του προβλήματος μέσω φυσικών και μαθηματικών προσεγγίσεων. Ωστόσο, λόγω προκλήσεων όπως οι άγνωστες περιβαλλοντικές παράμετροι και οι γωνίες ανάκλασης του φωτός, η έρευνα επικεντρώθηκε προς την ανάπτυξη μιας πιο πρακτικής λύσης. Η βασική καινοτομία της διατριβής είναι η δημιουργία ενός Αυτοπροσαρμοζόμενου Συστήματος Χρωματικής Βαθμονόμησης (Self-Adaptive Colour Calibration pipeline), το οποίο αξιοποιεί δεδομένα που προέρχονται από τις τεχνικές Structure from Motion (SfM) και Multi-View Stereo (MVS), καθώς και μεθόδους βαθιάς μάθησης, για την αποκατάσταση των πραγματικών χρωμάτων σε υποβρύχιες εικόνες χωρίς την ανάγκη λεπτομερούς γνώσης του περιβάλλοντος. Η προτεινόμενη μεθοδολογία διορθώνει αποτελεσματικά την υποβάθμιση των χρωμάτων σε αρχειακά σύνολα δεδομένων, απουσία φασματικών και περιβαλλοντικών πληροφοριών, γεγονός που την καθιστά ιδιαίτερα κατάλληλη για την αρχαιολογική υποβρύχια απεικόνιση και εφαρμογές με περιορισμένους πόρους. Τα αποτελέσματα από την εφαρμογή αυτής της μεθοδολογίας σε δεδομένα από δύο διαφορετικές υποβρύχιες τοποθεσίες, το ναυάγιο του Μαζωτού και το ναυάγιο Νησιά, αποδεικνύουν την ανθεκτικότητα και προσαρμοστικότητά της σε ποικίλες συνθήκες. Η αξιολόγηση με χρήση σημείων αναφοράς επιβεβαίωσε περαιτέρω την ικανότητα του συστήματος να αποκαθιστά με ακρίβεια τα χρώματα, αναδεικνύοντας τη δυναμική του για τη βελτίωση της υποβρύχιας απεικόνισης σε αρχαιολογικές και περιβαλλοντικές μελέτες.This PhD thesis addresses the challenge of colour attenuation in deep-water underwater images captured under artificial light. Initially, the research aimed to model and solve the issue through physical and mathematical approaches. However, due to challenges such as unknown environmental parameters and light reflection angles, the focus shifted to developing a more practical solution. The key innovation of this thesis is the creation of a Self-Adaptive Colour Calibration pipeline, which leverages Structure from Motion (SfM) and Multi-View Stereo (MVS) derived data, alongside DL techniques, to restore the true colours in underwater images without requiring detailed environmental knowledge. The proposed pipeline effectively corrects colour degradation in archival datasets, in the absence of spectral and environmental data, making it particularly suitable for archaeological underwater imaging and applications with limited resources. The results from the application of this methodology to datasets from two distinct underwater sites, Mazotos and Nissia, demonstrate its robustness and adaptability across varying conditions. A reference-based evaluation further confirmed the pipeline's ability to restore colours accurately, highlighting its potential for enhancing underwater imagery for archaeological and environmental studies.Dr. Fotis Liarokapis, Professor
Dr. Konstantinos Karantzalos, ProfessorComplete
Η Αμερικανίδα καλλιτέχνιδα Mary Cassatt στο πλαίσιο του ιμπρεσιονισμού
No full textThis thesis concerns the American artist Mary Cassatt, within the context of Impressionism and modernity, as well as the overall effort of women for independence and entry to the art academies during the 19th century. It foregrounds her presence, as a particularly active and influential member among the Impressionists, her artistic influences and technical means and, mostly, her ardent interest and modern approach tοwards a timeless theme – Mother and Child – which distinguishes her to this day among the other members of the group, men and women.Η παρούσα διατριβή ασχολείται με τη Αμερικανίδα καλλιτέχνιδα Mary Cassatt στο πλαίσιο του Ιμπρεσιονισμού και της νεωτερικότητας, όπως και την ολική προσπάθεια των γυναικών για ανεξαρτητοποίηση και την είσοδο τους στις ακαδημίες, κατά τον 19ο αιώνα. Στόχος είναι να αναδείξει την παρουσία της ως ένα ιδιαίτερα ενεργό και επιφανές μέλος των Ιμπρεσιονιστών, τις καλλιτεχνικές τις επιρροές, τα τεχνικά της μέσα και, κυρίως, το φλογερό ενδιαφέρον και τη σύγχρονη προσέγγιση της προς μία διαχρονική θεματική – με επίκεντρο τη Μητέρα και το Παιδί – που την ξεχωρίζει ανάμεσα στους υπόλοιπους καλλιτέχνες του Ιμπρεσιονισμού.Complete
Development of a Hybrid Gene Regulatory Network–Bioprocess Model to Enhance the Prediction of Bioethanol Production by Saccharomyces cerevisiae
No full textAlbeit bioprocess kinetics are typically predicted using empirical and unstructured models, a gap still exists in connecting bioprocess performance to the molecular events that control the efficiency of bioethanol production using Saccharomyces cerevisiae. Herein, a hybrid genetic regulatory network (GRN)–bioprocess model is proposed, predicting transcription from important genes (HXK2, PDC5, and ADH1) involved in the glucose-sensing, glycolysis, and bioethanol production processes, associating glucose consumption as well as biomass and bioethanol production rates to the regulatory events that control bioprocess kinetics. Parameter estimation and validation of the hybrid GRN–bioprocess model were conducted in batch trials supplemented with varying glucose contents via quantification of gene transcription levels. Calculation of the normalized root mean square error (NRMSE) confirmed that the hybrid model developed could accurately predict bioethanol production as opposed to the Monod model. NRMSE values ranged between 0.57–0.91 and 0.60–10.09 for the hybrid and Monod models, respectively, indicating enhanced performance of the novel approach proposed, which improved biomass concentration prediction by 89.4%, glucose concentration prediction by 16.2%, and bioethanol concentration prediction by 60.7% in the experiment conducted using an initial glucose content of 40 g L–1. The hybrid model introduced nonconstant transcription-dependent biomass and product yields as novel functions regulated by the plethora of interactions between the regulatory molecules of the pathways involved, offering substantially improved bioprocess prediction. The proposed framework advances our comprehension of the dynamic properties of bioethanol fermentation via consideration of complex cellular mechanisms controlling the synthesis of rate-limiting enzymes, which are typically ignored by the empirical/unstructured models often applied, providing a systematic understanding of bioethanol manufacture
Improving Light Stability of Nonfullerene Acceptor Inverted Organic Solar Cell by Incorporating a Mixed Nanocomposite Metal Oxide Electron Transporting Layer
No full textWe present significant light stability enhancement of nonfullerene acceptor inverted organic photovoltaics by incorporating a mixed nanocomposite metal oxide electron transporting layer. Using an appropriate mixture of ZnO:SnO2 nanoparticles as an electron transporting layer in a PBDB-TF-T1 (T1):IT4F based organic solar cell device mitigates light induced photodegradation by lowering the defect formation at the active layer interface. We propose that the mixed metal oxide ETL act as hole scavengers that reduces the photocatalytic reaction of its surface. The optimized nanocomposite mixture of ZnO:SnO2 10:90 (%V) provides higher light stability (ISOS-L2 protocol), prolonging the inverted OSCs lifetime (80% of the initial PCE, T80) by ∼16.5 times compared to the commonly used pristine ZnO electron transporting layer.This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 862474 (project RoLA-FLEX)
Towards Digitally Fabricated Pre-Industrial Materials
No full textOver the last year, we have been studying materials used to produce well-preserved antique furniture made in mainland Europe. These materials and techniques may today seem gruesome or unethical since they involve the use of animal bones and rabbit skin, but the actual final products can be disposed of as nutritious additions to household compost. The recipe tested was “Compo”, a dough-like substance widely used on 19th Century French heavily ornamented furniture and in Cypriot frame making.
This project sprung from the hypothesis that if the way we produce today is largely a consequence of the Industrial Revolution, then the re-introduction of pre-industrial techniques into modern systems of manufacture might bear some solutions to the problem of waste and overproduction.
After succeeding to revive the material and produce a classic Anglepoise 90 replica through “Compo” we are now ready to implement our material on an array of different products and forms.
At the moment the arising research questions contemplate how we can take advantage of contemporary laser cutting techniques and whether the material can be successfully 3D printed in a clay extruder in addition to traditional casting and moulding. Early results appear promising!
For the purposes of this presentation we will also present the most recent version of our recipe, our composting tests and our efforts to take advantage of waste (such as egg-shells) to develop it’s sustainable qualities
Stress testing OTC derivatives: Clearing reforms and market frictions
No full textWe develop a stress-testing network model calibrated to the largest banks and investment funds in over-the-counter (OTC) derivatives markets. We examine the impact of the mandatory collateralisation of bilateral OTC derivatives on liquidity, counterparty, and systemic risks, as well as the impact of market frictions on participants’ ability to withstand liquidity shocks. The collateralisation of bilateral trades reduces counterparty and systemic risks but increases the prominence of liquidity-driven defaults and the potential for the central counterparty to transmit losses. Frictions such as fire sales, delayed payments, and no partial payments by defaulted counterparties greatly increase liquidity risk and systemic losses
Delivery of Pediatric Student-Led Speech and Language Therapy Services at a University Rehabilitation Clinic in Cyprus: Children Accessing Services
No full textCO2 Conversion to Acetic Acid by Acetogen-Enriched Microbial Inocula with H2 Supplied by In-Situ Zero-Valent Metal Oxidation
No full textΚατά τις τελευταίες δεκαετίες, οι ανθρωπογενείς εκπομπές διοξειδίου του άνθρακα (CO₂) έχουν αυξηθεί δραματικά, οδηγώντας σε υπερβολικά επίπεδα CO₂ στην ατμόσφαιρα. Αυτή η αύξηση της συγκέντρωσης CO₂ έχει συμβάλει σημαντικά στην υπερθέρμανση του πλανήτη. Για τον λόγο αυτό, η Ευρωπαϊκή Ένωση (ΕΕ) και η επιστημονική κοινότητα αναζητούν ενεργά λύσεις.In the last decades, anthropogenic carbon dioxide (CO2) emissions have increased dramatically, leading to excessive CO2 levels in the atmosphere. This rise in CO2 concentration has contributed significantly to global warming. For this reason, the European Union (EU) and the scientific community have been actively seeking solutions.
This study presents an innovative, cost-effective, and sustainable solution for CO2 mitigation. This gas can be bioconverted into acetic acid by a mixed microbial consortium in a system supplemented with solid metals (zero-valent iron – Fe⁰, magnesium – Mg⁰, and waste iron – FeW) under mild, anaerobic, and carbonated conditions. The innovation focuses on producing the necessary H₂ gas in-situ - which serves as an electron donor and facilitates biological reactions - via the oxidation of metals to eliminate the reliance on external H2 supply.Δρ. Γιώργος Μπότσαρης
Δρ. Απόστολος ΚουτίναςComplete
Sequestering carbon without reducing food production: The role of recirculating aquaculture systems
No full textThe annual creation of 30,000 ha of woodland, a key component of UK's net-zero GHG emissions strategy, may drive countries exporting food to Great Britain (GB) to increase their emissions, an example of international carbon leakage. This can be mitigated by intensifying British domestic food production and our objective is to assess the viability of an intensification based on recirculating aquaculture systems (RAS), a land-saving technology recycling its own water. We built a computational partial equilibrium model whose supply side extended positive mathematical programming to aquaculture at grid-cell level. Agricultural censuses were combined with RAS financial data from a British research and business impact project. Results revealed that RAS was viable in 1.6 % of GB's farmland, substituting 28 % of current annual warmwater prawn imports. The implementation of GB's annual woodland creation goal also proved viable for farmers, but it induced, by shifting 0.2 % of agricultural area into woodland, a 0.007 % drop in food production, what would lead to international carbon leakage. RAS mitigated leakage completely and its contribution to food production was even larger when powered by anaerobic digesters. A lower interest rate charged on loans for RAS also boosted food production, which demonstrates financial sector's role in leakage mitigation