cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
title: Employing hypergraphs for efficient coalition formation with an application to electric vehicle cooperatives
title: Χρήση υπεργράφων για αποδοτική δημιουργία συνασπισμών με εφαρμογή σε συνεταιρισμούς ηλεκτρικών οχημάτων
Creators: name: Χριστιανος Φιλιππος
Publisher: name: Technical University of Crete
Year: 2017

description: Αυτή η διπλωματική εισάγει, για πρώτη φορά στη βιβλιογραφία, την χρήση υπεργράφων για την ταχεία δημιουργία αποτελεσματικών συνασπισμών αυτόνομων πρακτόρων. Προτείνουμε ορισμένες μεθόδους σχηματισμού, που βασίζονται σε υπάρχοντες αλγορίθμους υπεργράφων, όπως οι pruning, transversal, clustering και hybrid, και εκμεταλλευόμαστε την δομή του υπεργράφου για να εντοπίσουμε πράκτορες με επιθυμητά χαρακτηριστικά. Η προσέγγισή μας επιτρέπει τον σχεδόν στιγμιαίο σχηματισμό συνασπισμών υψηλής ποιότητας, ικανοποιώντας πολλαπλές ποιοτικές απαιτήσεις. Επιπλέον, οι μέθοδοί μας κλιμακώνονται ώστε να δέχονται δεκάδες χιλιάδες πράκτορες ως είσοδο και να εμφανίζουν τα αποτελέσματα μέσα σε κλάσματα του δευτερολέπτου, με μια από αυτές να λειτουργεί με εκατομμύρια πράκτορες μέσα σε δευτερόλεπτα. Εφαρμόζουμε την προσέγγισή μας στο πρόβλημα της δημιουργίας συνασπισμών για την παροχή ρεύματος από ηλεκτρικά οχήματα προς το ηλεκτρικό δίκτυο (το λεγόμενο πρόβλημα Vehicle-to-Grid, ή V2G). Η προσέγγισή μας είναι η πρώτη που είναι σε θέση να ασχοληθεί με μεγάλης κλίμακας, και σε πραγματικό χρόνο σχηματισμό συνασπισμών για το πρόβλημα V2G, λαμβάνοντας υπ'όψιν πολλαπλά κριτήρια για τη δημιουργία των συνασπισμών ηλεκτρικών οχημάτων. Ένα προσχέδιο των ιδεών αυτών εμφανίστηκε αρχικά σε μια σύντομη δημοσίευση στο 22ο European Conference on Artificial Intelligence (ECAI-2016) και έπειτα σε μια πλήρη στο 14o European Conference on Multi-Agent Systems (EUMAS-2016).
description: This thesis proposes, for the first time in the literature, the use of hypergraphs for the efficient formation of effective agent coalitions. We put forward several formation methods that build on existing hypergraph pruning, transversal, clustering and hybrid algorithms, and exploit the hypergraph structure to identify agents with desirable characteristics. Our approach allows the near-instantaneous formation of high quality coalitions, adhering to multiple stated quality requirements. Moreover, our methods are shown to scale to dozens of thousands of agents within fractions of a second; with one of them scaling to even millions of agents within seconds. We apply our approach to the problem of forming coalitions to provide (electric) vehicle-to-grid (V2G) services. Ours is the first approach able to deal with large-scale, real-time coalition formation for the V2G problem, while taking multiple criteria into account for creating the electric vehicle coalitions. A sketch of these ideas appeared originally in a short paper in the 22nd European Conference on Artificial Intelligence (ECAI-2016). Afterwards, a full paper describing our work was published in the 14th European Conference on Multi-Agent Systems (EUMAS-2016).
Quantal corrections to mean-field dynamics including pairing
Creators: name: Lacroix, Denis
name: Gambacurta, Danilo
name: Ayik, Sakir
Publisher: name: arXiv
Year: 2013
Subjects: subject: Nuclear Theory (nucl-th)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Nuclear Experiment (nucl-ex)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Extending the stochastic mean-field model by including pairing, an approach is proposed for describing evolutions of complex many-body systems in terms of an ensemble of Time-Dependent Hartree-Fock Bogoliubov trajectories which is determined by incorporating fluctuations in the initial state. Non-linear evolution of the initial fluctuations provides an approximate description of quantal correlations and fluctuations of collective observables. Since the initial-state fluctuations break the particle-number symmetry, the dynamical description in which pairing correlations play a crucial role is greatly improved as compare to the mean-field evolution. The approach is illustrated for a system of particles governed by a pairing Hamiltonian.
description: 5 pages, 2 figures, To appear in Phys. Rev. C (Rapid communication)
title: Design and implementation of a multi-FPGA acceleration system for large-scale population genomics analyses based on linkage disequilibrium
title: Σχεδίαση και υλοποίηση συστήματος πολλαπλών FPGA για την επιτάχυνση μεγάλης κλίμακας αναλύσεων πληθυσμιακής γενομικής βασιζόμενες σε ανισορροπία σύνδεσης
Creators: name: Μποζικας Δημητριος
Publisher: name: Technical University of Crete
Year: 2017

description: Modern sequencing technologies have contributed to the creation and rapid expansion of DNA databases, already numbering thousands of whole genomes. The astonishing rate at which genomic data are being collected, combined with the fact that it has outpaced Moore’s law, establishes the necessity of the development of novel tools, capable of conducting large-scale genomics analyses efficiently. This work addresses the computational challenges inherent to the analysis of linkage disequilibrium (LD) levels in large-scale datasets. LD is a statistic that quantifies the non-random association between alleles at different genomic locations. While it contributes to a wide variety of genomics and genetics analyses, the compute- and memory-intensive operation of counting set bits (population count) in large vectors, required for the estimation of LD, hinders the efficient use of modern CPUs for such
analyses, mainly due to the lack of a vectorized population counter. To overcome this obstacle, we present a novel hardware architecture for the calculation of pairwise LD scores based on reconfigurable logic. The proposed accelerator exploits the ability of reconfigurable machines to be programmed at the hardware level. The effective use of multiple levels of parallelism, combined with the efficient manipulation of the data structures on memory through the transformation of the memory layout, result in high throughput capabilities for the estimation of LD in arbitrarily large datasets. The architecture is, subsequently, mapped onto a high-performance heterogeneous computing platform that enables the parallel cooperation of 4 reconfigurable devices, while, simultaneously, providing a high-speed memory interface. The implemented accelerator is evaluated for analyses of simulated genomic data of varying sizes, through its comparison with corresponding state-of-the-art parallel software implementations, achieving speedups between 6.35X and 134.93X, depending on the dataset size. Concerning real-world analyses, such as scanning the 22nd chromosome of the human genome, the accelerator is capable of potentially achieving quintupled throughput when compared to highly optimized reference software running on multiple cores.
title: Επεξεργαστής για προσομοίωση νευροβιολογικών διεργασιών βασισμένος σε αναδιατασσόμενη λογική
title: Reconfigurable logic-based processor for the simulation of neurobiological processes
Creators: name: Κουσανακης Εμμανουηλ
Publisher: name: Technical University of Crete
Year: 2017

description: Neuromorphic computing is expanding by leaps and bounds through custom integrated circuits (both digital and analog), and large scale platforms developed by industry and by government funded large projects (e.g. TrueNorth and BrainScaleS, respectively). Whereas the trend is for massive parallelism and neuromorphic computation in order to solve problems, such as those that may appear in machine learning and deep learning algorithms, there is substantial work on brain-like neuromorphic computing with a high degree of precision and accuracy, in order to model the human brain. In such a form of computing, spiking neural networks (SNN) such as the Hodgkin and Huxley model are mapped to various technologies, including FPGAs. In this work, we present a highly efficient FPGA-based architecture for the detailed hybrid Leaky Integrate and Fire SNN that can simulate generic characteristics of neurons of the cerebral cortex. This architecture supports arbitrary, sparse O(n2) interconnection of neurons without need to re-compile the design, and plasticity rules, yielding on a four-FPGA Convey 2ex hybrid computer a speedup of 823x for a non-trivial data set on 240 neurons vs. the same model in the software simulator BRAIN on a Intel(R) Xeon(R) CPU E5-2620 v2 @ 2.10GHz, i.e. the reference state-of-the-art software. Although the reference, official software is single core, the speedup demonstrates that the application scales well among multiple FPGAs, whereas this would not be the case in general-purpose computing approaches due to the arbitrary interconnect requirements. The FPGA-based approach leads to highly detailed models of parts of the human brain up to a few hundred neurons vs. a dozen or fewer neurons on the reference system.
Random packing of spheres in Menger sponge
Creators: name: Cieśla, Michał
name: Barbasz, Jakub
Publisher: name: arXiv
Year: 2013
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Random packing of spheres inside fractal collectors of dimension 2 < d < 3 is studied numerically using Random Sequential Adsorption (RSA) algorithm. The paper focuses mainly on the measurement of random packing saturation limit. Additionally, scaling properties of density autocorrelations in the obtained packing are analyzed. The RSA kinetics coefficients are also measured. Obtained results allow to test phenomenological relation between random packing saturation density and collector dimension. Additionally, performed simulations together with previously obtained results confirm that, in general, the known dimensional relations are obeyed by systems having non-integer dimension, at least for d < 3.
description: 13 pages, 6 figures
The SAGIT® instrument for the classification of acromegaly
Creators: name: Giustina, Andrea
name: Bronstein, Marcello D.
name: Chanson, Philippe
name: Petersenn, Stephan
name: Casanueva, Felipe F
name: Sert, Caroline
name: Houchard, Aude
name: Melmed, Shlomo
Publisher: name: figshare
Year: 2021
Subjects: Medicine

description: The SAGIT® instrument (SAGIT) has been developed to help practicing endocrinologists to better characterize disease activity, providing a precise classification of acromegaly severity. SAGIT reflects key components associated with management of acromegaly, namely signs and symptoms (S), associated comorbidities (A), GH levels (G), IGF-1 levels (I), and tumor features (T). Each of the five components is scored by a clinician, with higher scores reflecting increased disease severity.
Phases of the net-zero energy transition and strategies to achieve it
Creators: name: Markard, Joche
name: Rosenbloom, Daniel
Publisher: name: arXiv
Year: 2023
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Systems and Control (eess.SY)
subject: FOS: Physical sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: The net-zero energy transition is an extraordinary societal challenge. It requires a swift, radical and economy wide transformation. With the aim of informing research and policy, we identify general phases of this transition and the overarching strategies that may be brought to bear in tackling this challenge. Drawing from the literature on sustainability transition studies, we depict the net-zero energy transition as a non-linear, cumulative process that involves multiple, interdependent transitions in different sectors. Future emission targets can only be reached if policymaking will play a strong role in guiding these transitions. To understand the increasing complexity of the policy challenge, we distinguish four overlapping phases of development: emergence of low-carbon innovations, transition of a single sector (electricity), transitions of multiple sectors based on low-carbon electricity, and transitions in difficult-to-decarbonize sectors. We argue that each phase comes with new policy challenges on top of the already existing ones. Finally, we discuss the merits and limitations of five general strategies for decarbonization: efficiency improvement, low-carbon electrification, low-carbon fuels, negative emissions and "untapped demand-side approaches." While electrification has emerged as the dominant strategy, new low-carbon fuels (e.g., based on hydrogen) but also more radical changes (e.g., substitution of carbon-intensive products or lifestyle changes) merit further attention.
Constraints on the Tensor-to-Scalar ratio for non-power-law models
Creators: name: Vazquez, J. Alberto
name: Bridges, M.
name: Ma, Yin-Zhe
name: Hobson, M. P.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Recent cosmological observations hint at a deviation from the simple power-law form of the primordial spectrum of curvature perturbations. In this paper we show that in the presence of a tensor component, a turn-over in the initial spectrum is preferred by current observations, and hence non-power-law models ought to be considered. For instance, for a power-law parameterisation with both a tensor component and running parameter, current data show a preference for a negative running at more than $2.5σ$ C.L. As a consequence of this deviation from a power-law, constraints on the tensor-to-scalar ratio $r$ are slightly broader. We also present constraints on the inflationary parameters for a model-independent reconstruction and the Lasenby & Doran (LD) model. In particular, the constraints on the tensor-to-scalar ratio from the LD model are: $r_{\rm LD}=0.11\pm{0.024}$. In addition to current data, we show expected constraints from Planck-like and CMB-Pol sensitivity experiments by using Markov-Chain-Monte-Carlo sampling chains. For all the models, we have included the Bayesian Evidence to perform a model selection analysis. The Bayes factor, using current observations, shows a strong preference for the LD model over the standard power-law parameterisation, and provides an insight into the accuracy of differentiating models through future surveys.
description: Minor changes to match version accepted by JCAP
Critical solutions in topologically gauged N=8 CFTs in three dimensions
Creators: name: Nilsson, Bengt E. W.
Publisher: name: arXiv
Year: 2013
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: In this paper we discuss some special (critical) background solutions that arise in topological gauged ${\mathcal N}=8$ three-dimensional CFTs with SO(N) gauge group. These solutions solve the TMG equations (containing the parameters $μ$ and $l$) for a certain set of values of $μl$ obtained by varying the number of scalar fields with a VEV. Apart from Minkowski, chiral round $AdS_3$ and null-warped $AdS_3$ (or Schrödinger(z=2)) we identify also a more exotic solution recently found in $TMG$ by Ertl, Grumiller and Johansson. We also discuss the spectrum, symmetry breaking pattern and the supermultiplet structure in the various backgrounds and argue that some properties are due to their common origin in a conformal phase. Some of the scalar fields, including all higgsed ones, turn out to satisfy three-dimensional singleton field equations. Finally, we note that topologically gauged ${\mathcal N}=6$ ABJ(M) theories have a similar, but more restricted, set of background solutions.
description: 34 pages, v2: minor corrections, note about a new solution added in final section, v3: two footnotes added
title: Morphological restoration of the Venetian Mansion in Katochori, Keramia

title: Μορφολογική αποκατάσταση της Ενετικής Έπαυλης Κατωχωρίου, Δ.Δ. Κεραμείων
Creators: name: Μπουρμπακης Κωνσταντινος
Publisher: name: Technical University of Crete
Year: 2018

description: Η ενετική έπαυλη που βρίσκεται στο Κατωχώρι των Κεραμειών, αποτελεί χαρακτηριστικό δείγμα φεουδαρχικής κατοικίας της ύστερης Ενετοκρατίας και διακρίνεται για την επιμελημένη κατασκευή της. Σκοπός της εργασίας είναι η παρουσίαση πρότασης μορφολογικής αποκατάστασης του μνημείου απαντώντας στα βασικά ερωτήματα, που θέτει η θεωρία της συντήρησης και της αποκατάστασης ενός αρχιτεκτονικού έργου. Αναγνωρίζοντας τις μεταγενέστερες επεμβάσεις, που έλαβαν χώρα στο μνημείο έγινε προσπάθεια απόδοσης της αρχικής μορφής που είχε η έπαυλη κατά την περίοδο της Ενετοκρατίας, καθώς σε συνδυασμό με τους δύο ήδη αποκατεστημένους παρακείμενους ναούς, δύναται να αποδοθεί ως συγκρότημα κοσμικής και εκκλησιαστικής αρχιτεκτονικής της κρητικής υπαίθρου. Με αυτόν τον τρόπο αναδεικνύεται η μοναδικότητα του συμπλέγματος στον ελλαδικό χώρο και τονίζεται ότι η αποκατάστασή της έπαυλης αποτελεί αδήριτη ανάγκη για την περαιτέρω ανάδειξη της πολιτιστικής κληρονομιάς της ευρύτερης περιοχής.
description: The Venetian villa, located in Katochori, Keramia, is a typical example of a feudal residence of the late Venetian era and is distinguished by its elaborate construction. The aim of this thesis is to submit a proposal for the morphological restoration of the monument by defying the basic questions posed by the theory of conservation and the restoration of an architectural work. Acknowledging the subsequent interventions that took place in the monument, an attempt was made to redeem the original form of the villa during the Venetian period, since in combination with the two adjoining temples, it can be attributed as a complex of secular and ecclesiastical architecture of the Cretan countryside. In this way, it is highlighted the uniqueness of the complex in Greece’s area and it is emphasized that the restoration of the villa is an imperative need for the further enhancement of the cultural heritage of the wider region.
title: Προώθηση της βιώσιμης αστικής κινητικότητας: η περίπτωση του Δήμου Ζωγράφου
title: Sustainable urban mobility: study case of Municipality of Zografou
Creators: name: Αλεξοπουλου Νεφελη-Ευαγγελια
Publisher: name: Technical University of Crete
Year: 2018

description: Ο δήμος Ζωγράφου, όμορος του δήμου Αθηνών, βρίσκεται στους πρόποδες του Υμηττού, παρουσιάζοντας έντονο γεωγραφικό ανάγλυφο, ενώ χαρακτηρίζεται από τη φοιτητική ζωή καθώς φιλοξενεί τα δύο μεγαλύτερα εκπαιδευτικά ιδρύματα της χώρας (ΕΜΠ, ΕΚΠΑ). Πρόσφατες έρευνες κατέταξαν το δήμο στην πέμπτη θέση των πιο πυκνοκατοικημένων περιοχών της Ευρώπης.
Η κινητικότητα στο δήμο, αποτελεί πρόκληση τόσο για τους μόνιμους κατοίκους όσο και για τον καθημερινό φόρτο που δέχεται από τη λειτουργία των ιδρυμάτων. Στην παρούσα διπλωματική εργασία, παρουσιάζεται ο δήμος Ζωγράφου, τα ιδιαίτερα χαρακτηριστικά του, τα δίκτυα του αστικού ιστού ενώ παράλληλα καταγράφονται οι ελλείψεις και οι σύγχρονες ανάγκες του. Οι προτεινόμενες επεμβάσεις, στοχεύουν στην προώθηση της μη μηχανοκίνητης κίνηση και στην ανάδειξή της ως βασική αστική λειτουργία. Παράλληλα, δίνονται κατευθύνσεις για την ένταξη τεχνολογικών συστημάτων τα οποία διασφαλίζουν απρόσκοπτη και ασφαλή κινητικότητα στο πλαίσιο του δήμου.
description: The municipality of Zografou, adjacent to the municipality of Athens, is located at the base of mt.  Hymettus, showing a strong geographical morphology. The city is characterized by the student life as it hosts the two largest educational institutions in the country. Recent surveys ranked the municipality as the fifth densest area of Europe. Mobility in the municipality, is a challenge both for permanent residents and for those who commute for educational reasons. In the first part of this diploma thesis, we introduce the audience to the particular characteristics of Zografou, describing the conditions and recording the modern needs of the citizens. The proposed interventions aim to promote non-motorized traffic and its emergence as basic urban function. At the same time, guidance is given to integrate technological systems that ensure unobstructed and secure mobility within the municipality.
Development of a closed-loop, implantable, electroceutical device for gastric disorders
Creators: name: Ganesh, Vivek
Publisher: name: Purdue University Graduate School
Year: 2022
Subjects: Electrical circuits and systems
Biomedical instrumentation
Biomedical engineering not elsewhere classified
Circuits and systems

description: Gastroparesis and functional dyspepsia are debilitating stomach disorders that together affect 10% of the world population. Modulating gastric function is an important target function for alternative therapies like gastric electrical stimulation (GES). The Enterra device is the only FDA approved implantable device currently available that can administer GES to entrain gastric slow wave activity. However, recent evidence has called into question the clinical utility of this system. In this work, I present the development and in vivo application of a new, closed loop, chronically implantable electroceutical device capable of continuously recording gastric motility and administering synchronous GES, that will form the needed foundation for neuromodulation protocols that can correct shortcomings in past, first-generation bioelectronic attempts to ameliorate and monitor gastric disorders. This system captures gastric serosal myoelectric activity using electrogastrography, as well as gastric contraction activity using strain gauge force transducers. I present data captured from anesthetized and freely behaving rats, demonstrating the ability of the device to capture physiologically relevant gastric motility patterns and changes, safely and effectively. I present a framework built on continuous wavelet transforms to analyze frequency and amplitude changes in captured data to inform potential therapies. I present data demonstrating the ability of the device to selectively stimulate enteric neurons in sync with gastric slow waves, resulting in a relaxation of the pyloric sphincter muscle, in a closed loop fashion. I present the development of a large animal preclinical proof-of-principle version of this system, and data captured from its implantation in freely behaving pigs, as a translational step to future human trials. In the future, this system will enable further studies into future closed loop therapies aimed at increasing gastric accommodation, stimulating physiological gastric emptying and/or pyloric opening with physiologically appropriate timing and extent.
First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole
Creators: name: The Event Horizon Telescope Collaboration
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: In this paper, we provide a first physical interpretation for the Event Horizon Telescope (EHT)'s 2017 observations of Sgr A*. Our main approach is to compare resolved EHT data at 230 GHz and unresolved non-EHT observations from radio to X-ray wavelengths to predictions from a library of models based on time-dependent general relativistic magnetohydrodynamics (GRMHD) simulations, including aligned, tilted, and stellar wind-fed simulations; radiative transfer is performed assuming both thermal and non-thermal electron distribution functions. We test the models against 11 constraints drawn from EHT 230 GHz data and observations at 86 GHz, 2.2 $μ$m, and in the X-ray. All models fail at least one constraint. Light curve variability provides a particularly severe constraint, failing nearly all strongly magnetized (MAD) models and a large fraction of weakly magnetized (SANE) models. A number of models fail only the variability constraints. We identify a promising cluster of these models, which are MAD and have inclination $i \le$ 30$^\circ$. They have accretion rate $(5.2$-$9.5)\times10^{-9}M_\odot$yr$^{-1}$, bolometric luminosity $(6.8$--$9.2)\times10^{35}$ erg s$^{-1}$, and outflow power $(1.3$--$4.8)\times10^{38}$ erg s$^{-1}$. We also find that: all models with $i \ge$ 70$^\circ$ fail at least two constraints, as do all models with equal ion and electron temperature; exploratory, non-thermal model sets tend to have higher 2.2 $μ$m flux density; the population of cold electrons is limited by X-ray constraints due to the risk of bremsstrahlung overproduction. Finally we discuss physical and numerical limitations of the models, highlighting the possible importance of kinetic effects and duration of the simulations.
description: 62 pages, 35 figures, published in The Astrophysical Journal Letters on May 12, 2022. See the published paper for the full authors list
Quasiparticle mass enhancement close to the quantum critical point in BaFe$_2$(As$_{1-x}$P$_x$)$_2$
Creators: name: Walmsley, P.
name: Putzke, C.
name: Malone, L.
name: Guillamon, I.
name: Vignolles, D.
name: Proust, C.
name: Badoux, S.
name: Coldea, A. I.
name: Watson, M. D.
name: Kasahara, S.
name: Mizukami, Y.
name: Shibauchi, T.
name: Matsuda, Y.
name: Carrington, A.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We report a combined study of the specific heat and de Haas-van Alphen effect in the iron-pnictide superconductor BaFe$_2$(As$_{1-x}$P$_x$)$_2$. Our data when combined with results for the magnetic penetration depth give compelling evidence for the existence of a quantum critical point (QCP) close to $x=0.30$ which affects the majority of the Fermi surface by enhancing the quasiparticle mass. The results show that the sharp peak in the inverse superfluid density seen in this system results from a strong increase in the quasiparticle mass at the QCP.
description: 5 pages
First Sagittarius A* Event Horizon Telescope Results. III: Imaging of the Galactic Center Supermassive Black Hole
Creators: name: The Event Horizon Telescope Collaboration
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present the first event-horizon-scale images and spatiotemporal analysis of Sgr A* taken with the Event Horizon Telescope in 2017 April at a wavelength of 1.3 mm. Imaging of Sgr A* has been conducted through surveys over a wide range of imaging assumptions using the classical CLEAN algorithm, regularized maximum likelihood methods, and a Bayesian posterior sampling method. Different prescriptions have been used to account for scattering effects by the interstellar medium towards the Galactic Center. Mitigation of the rapid intra-day variability that characterizes Sgr A* has been carried out through the addition of a "variability noise budget" in the observed visibilities, facilitating the reconstruction of static full-track images. Our static reconstructions of Sgr A* can be clustered into four representative morphologies that correspond to ring images with three different azimuthal brightness distributions, and a small cluster that contains diverse non-ring morphologies. Based on our extensive analysis of the effects of sparse $(u,v)$-coverage, source variability and interstellar scattering, as well as studies of simulated visibility data, we conclude that the Event Horizon Telescope Sgr A* data show compelling evidence for an image that is dominated by a bright ring of emission with a ring diameter of $\sim$ 50 $μ$as, consistent with the expected "shadow" of a $4\times10^6 M_\odot$ black hole in the Galactic Center located at a distance of 8 kpc.
description: 81 pages, 45 figures, published in The Astrophysical Journal Letters on May 12, 2022. See the published paper for the full authors list
title: Η πόλη μέσα στην πόλη: μια ανάλυση πλήρους - κενού
title: The City in the City: a figure - ground analysis
Creators: name: Κυριακιδου Ειρηνη
Publisher: name: Technical University of Crete
Year: 2018

description: Ο όρος “the city in the city” αναφέρεται σε ένα κτιριακό συγκρότημα ή ένα σύνολο οικοδομικών τετραγώνων, που αποτελούν έναν αυτόνομο κόσμο, μία μινιατούρα του συνόλου από το οποίο κατασκευάζονται. Η πανεπιστημιο-πολη αποτελεί μια μικρογραφία της πόλης  που την φιλοξενεί, καθώς συχνά διέπεται από τις ίδιες οργανωτικές και δομικές αρχές, τις οποίες χρησιμοποιεί για την δημιουργία ενός κοινοτικού περιβάλλοντος. Η διερεύνηση της σχέσης που αναπτύσσουν πόλη-πανεπιστημιούπολη στα σημεία επαφής τους, αποτελεί το αντικείμενο της παρούσας εργασίας και πραγματοποιείται με την μελέτη συγκεκριμένων παραδειγμάτων. Ως αναλυτικό εργαλείο επιλέγεται το πλήρες - κενό, μια γραφιστική τεχνική που απλοποιεί τα χωρικά φαινόμενα σ’ ένα δυαδικό κώδικα, μαύρο - άσπρο, δομημένο - αδόμητο (…)
description: The term “the city in the city” refers to a building complex or a number of city blocks which make up an autonomous universe, a miniature of the whole which they are part of. Similarly, the campus is a microcosmos, making use of the organizational and structural principles of the host city to construct a communal environment. The expansion of this relation between city and campus is the focus of the present project and specific examples are being studied. As an analytical tool, I have chosen figure ground, a graphic design technique simplifying the spatial phenomena in a binary code, black and white, structured – unstructured (…)
title: Δυο παράλληλες πορείες μιας διαιρεμένης πόλης: η περίπτωση της Λευκωσίας
title: Two parallel paths of a divided city: the case of Nicosia
Creators: name: Γεωργιου Στεφανια
Publisher: name: Technical University of Crete
Year: 2018

description: Οι κοινωνικές σχέσεις σχετίζονται τόσο συχνά και αναπόφευκτα με τις χωρικές σχέσεις». (Robert E Park). Όλες οι πόλεις υφίστανται διαχωρισμό, εφόσον οι διάφορες ομάδες που δρουν στον αστικό χώρο έχουν διαφορετικά συμφέροντα και φιλοδοξίες που υπαγορεύονται από τις διακρίσεις τάξεις, εθνικότητας και φύλου. Μια γενική ανασκόπηση στην εξέλιξη της κάθε πόλης αποκαλύπτει μια διαφορετική σειρά λόγων, παραγόντων και διαστάσεων ως κινητήρια δύναμη της διαίρεσης της κάθε πόλης και αναπόφευκτα παράγουν διαφορετικούς τύπους και εκφάνσεις διαίρεσης. Στην παρούσα εργασία, αναλύεται η περίπτωση της Λευκωσίας, της τελευταίας διαιρεμένης πρωτεύουσας στην Ευρώπη. Αρχικά εξετάζεται η διαχρονική εξέλιξη από την ανεξαρτησία της Κυπριακής Δημοκρατίας, με σημαντικό σταθμό στην πορεία της πόλης, την Τούρκικη εισβολή του 1974 και πως αυτή αποτυπώνεται χωρικά στο σύνολο της πόλης. Αναλύονται οι τρόποι επέκτασης του κατεχόμενου και του ελεύθερου κομματιού της πόλης, πως αντιμετωπίστηκε το θέμα της στέγασης και κατ’ επέκταση πως διαμορφώθηκε η σημερινή δομή της πόλης. Μέσα από τη μελέτη, εντοπίζονται οι ομοιότητες και οι διαφορές που αναπτύσσουν οι δύο κοινότητες στην διαμόρφωση του αστικού ιστού όπως και τα χωρικά σημάδια που αφήνει ο διαχωρισμός μιας πόλης.
Stochastic homogenization on perforated domains II - Application to nonlinear elasticity models
Creators: name: Heida, Martin
Publisher: name: Weierstrass Institute
Year: 2021
Subjects: subject: Homogenization
subject: stochastic geometry
subject: elasticity
subject: 54E45
subject: 60D05
subject: 74Qxx
subject: 76M50
subject: 80M40

description: Based on a recent work that exposed the lack of uniformly bounded W1,p → W1,p extension operators on randomly perforated domains, we study stochastic homogenization of nonlinear elasticity on such structures using instead the extension operators constructed in [11]. We thereby introduce two-scale convergence methods on such random domains under the intrinsic loss of regularity and prove some generally useful calculus theorems on the probability space Ω, e.g. abstract Gauss theorems.
Competing supersolids of Bose-Bose mixtures in a triangular lattice
Creators: name: Trousselet, F.
name: Rueda, P.
name: Ralko, A.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: We study the ground state properties of a frustrated two-species mixture of hard-core bosons on a triangular lattice, as a function of tunable amplitudes for tunnelling and interactions. By combining three different methods, a self-consistent cluster mean-field, exact diagonalizations and effective theories, we unravel a very rich and complex phase diagram. More specifically, we discuss the existence of three original mixture supersolids: (i) a commensurate with frozen densities and supersolidity in spin degrees of freedom, in a regime of strong interspecies interactions; and (ii) when this interaction is weaker, two mutually competing incommensurate supersolids. Finally, we show how these phases can be stabilized by a quantum fluctuation enhancement of peculiar insulating parent states.
description: 6 pages, 9 figures
title: Σύγχρονες μουσειακές προσεγγίσεις για τις προϊστορικές αρχαιότητες
title: Modern museum approaches to prehistoric antiquities
Creators: name: Μιχαλογιαννης Ηλιας
Publisher: name: Technical University of Crete
Year: 2018

description: Οι επικρατούσες θεωρίες για την παρουσίαση των αρχαιοτήτων της Προϊστορίας σε ένα μουσείο αντιλαμβάνονταν τον επισκέπτη ως παθητικό δέκτη. Μια συγκριτική παρουσίαση των παλαιότερων και των νεότερων θεωριών φανερώνει την αναβάθμιση των μουσείων και την ένταξη τους σε ένα ευρύτερο κοινωνικό και χωροταξικό πλαίσιο. Επίσης, παρατηρείται ο τρόπος με τον οποίο εξελίσσεται η αρχιτεκτονική των μουσείων ανά τους αιώνες, από τις πρώτες Βασιλικές συλλογές μέχρι τα μεταμοντέρνα μουσεία. Η επίδραση των νέων τεχνολογιών ανοίγει νέους ορίζοντες για την περαιτέρω εξέλιξη των μουσείων γενικότερα, και των προϊστορικών μουσείων ειδικότερα.
First Sagittarius A* Event Horizon Telescope Results. VI: Testing the Black Hole Metric
Creators: name: The Event Horizon Telescope Collaboration
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Astrophysical black holes are expected to be described by the Kerr metric. This is the only stationary, vacuum, axisymmetric metric, without electromagnetic charge, that satisfies Einstein's equations and does not have pathologies outside of the event horizon. We present new constraints on potential deviations from the Kerr prediction based on 2017 EHT observations of Sagittarius A* (Sgr A*). We calibrate the relationship between the geometrically defined black hole shadow and the observed size of the ring-like images using a library that includes both Kerr and non-Kerr simulations. We use the exquisite prior constraints on the mass-to-distance ratio for Sgr A* to show that the observed image size is within $\sim$ 10$\%$ of the Kerr predictions. We use these bounds to constrain metrics that are parametrically different from Kerr as well as the charges of several known spacetimes. To consider alternatives to the presence of an event horizon we explore the possibility that Sgr A* is a compact object with a surface that either absorbs and thermally re-emits incident radiation or partially reflects it. Using the observed image size and the broadband spectrum of Sgr A*, we conclude that a thermal surface can be ruled out and a fully reflective one is unlikely. We compare our results to the broader landscape of gravitational tests. Together with the bounds found for stellar mass black holes and the M87 black hole, our observations provide further support that the external spacetimes of all black holes are described by the Kerr metric, independent of their mass.
description: 55 pages, 27 figures, published in The Astrophysical Journal Letters on May 12, 2022. See the published paper for the full authors list
Revealing inverted chirality of hidden domain wall states in multiband systems without topological transition
Creators: name: Jeong, Seung-Gyo
name: Han, Sang-Hoon
name: Kim, Tae-Hwan
name: Cheon, Sangmo
Publisher: name: arXiv
Year: 2023
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Chirality, a fundamental concept from biological molecules to advanced materials, is prevalent in nature. Yet, its intricate behavior in specific topological systems remains poorly understood. Here, we investigate the emergence of hidden chiral domain wall states using a double-chain Su-Schrieffer-Heeger model with interchain coupling specifically designed to break chiral symmetry. Our phase diagram reveals single-gap and double-gap phases based on electronic structure, where transitions occur without topological phase changes. In the single-gap phase, we reproduce chiral domain wall states, akin to chiral solitons in the double-chain model, where chirality is encoded in the spectrum and topological charge pumping. In the double-gap phase, we identify hidden chiral domain wall states exhibiting opposite chirality to the domain wall states in the single-gap phase, where the opposite chirality is confirmed through spectrum inversion and charge pumping as the corresponding domain wall slowly moves. By engineering gap structures, we demonstrate control over hidden chiral domain states. Our findings open avenues to investigate novel topological systems with broken chiral symmetry and potential applications in diverse systems.
Singular value correlation functions for products of Wishart random matrices
Creators: name: Akemann, Gernot
name: Kieburg, Mario
name: Wei, Lu
Publisher: name: arXiv
Year: 2013
Subjects: subject: Mathematical Physics (math-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Information Theory (cs.IT)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences
subject: 15B52, 33C20, 33C45, 94Axx

description: Consider the product of $M$ quadratic random matrices with complex elements and no further symmetry, where all matrix elements of each factor have a Gaussian distribution. This generalises the classical Wishart-Laguerre Gaussian Unitary Ensemble with M=1. In this paper we first compute the joint probability distribution for the singular values of the product matrix when the matrix size $N$ and the number $M$ are fixed but arbitrary. This leads to a determinantal point process which can be realised in two different ways. First, it can be written as a one-matrix singular value model with a non-standard Jacobian, or second, for $M\geq2$, as a two-matrix singular value model with a set of auxiliary singular values and a weight proportional to the Meijer $G$-function. For both formulations we determine all singular value correlation functions in terms of the kernels of biorthogonal polynomials which we explicitly construct. They are given in terms of hypergeometric and Meijer $G$-functions, generalising the Laguerre polynomials. Our investigation was motivated from applications in telecommunication of multi-layered scattering MIMO channels. We present the ergodic mutual information for finite-$N$ for such a channel model with $M-1$ layers of scatterers as an example.
description: 23 pages, 4 figures, PACS: 02.10.Yn, 02.30.Cj, 02.30.Ik, 02.50.Sk, 84.40.Ba, 84.40.Ua
On the wave energy potential of Western Black Sea shelf
Creators: name: Galabov, Vasko
Publisher: name: arXiv
Year: 2013
Subjects: subject: Atmospheric and Oceanic Physics (physics.ao-ph)
subject: FOS: Physical sciences

description: In the present study we evaluate the approaches to estimate the wave energy potential of the western Black Sea shelf with numerical models. For the purpose of our evaluation and due to the lack of long time series of measurements in the selected area of the Black Sea, we compare the modeled mean wave power flux output from the SWAN wave model with the only available long term measurements from the buoy of Gelendzhik for the period 1997-2003 (with gaps). The forcing meteorological data for the numerical wave models for the selected years is extracted from the ERA Interim reanalysis of ECMWF (European Centre for Medium range Forecasts). For the year 2003 we also compare the estimated wave power with the modeled by SWAN, using ALADIN regional atmospheric model winds. We try to identify the shortcomings and limitations of the numerical modeling approach to the evaluation of the wave energy potential in Black Sea.
description: Geoconference SGEM 2013
title: Μελέτη, σχεδιασμός και υλοποίηση σε αναδιατασσόμενη λογική, αρχιτεκτονικής για τον παράλληλο υπολογισμό βέλτιστων κανόνων Golomb (GE3)
Creators: name: Μαλακωνάκης Παύλος
Publisher: name: Technical University of Crete
Year: 2009

description: Μη διαθέσιμο
title: Πειραματική μελέτη σειριακής εισόδου/εξόδου υψηλών ταχυτήτων σε ενσωματωμένα συστήματα FPGA
Creators: name: Σπυρόπουλος Κυριάκος
Publisher: name: Technical University of Crete
Year: 2009

description: Μη διαθέσιμο
title: Μελέτη, σχεδίαση και υλοποίηση σε αναδιατασσόμενη λογική του αλγόριθμου CE για σύγκριση πρωτεϊνών ως προς την τριτοταγή τους δομή
Creators: name: Καγιαβάς Χρίστος
Publisher: name: Technical University of Crete
Year: 2009

description: Μη διαθέσιμο
title: Σχεδίαση ενός κυκλώματος πολύ υψηλής ολοκλήρωσης για την εκτέλεση του αλγορίθμου βιοπληροφορικής BLASTn
Creators: name: Μαστρογιαννόπουλος Δημήτρης
Publisher: name: Technical University of Crete
Year: 2009

description: Μη διαθέσιμο
title: MPEG-4, H.264 and H.265 video Bandwidth prediction via markovian models and Simulated Annealing
title: Πρόβλεψη απαιτούμενου Bandwidth για ταινίες HPEG-4, H.264 & H.265 μέσω μαρκοβιανών μοντέλων και του αλγόριθμου Simulated Annealing
Creators: name: Καλαμπογια Αθηνα
Publisher: name: Technical University of Crete
Year: 2017

description: The explosive growth of multimedia applications renders the efficiency of network resource allocation a problem of major importance. The burstiness of video traffic, in particular, calls for traffic control solutions that will help prevent significant packet losses. Such losses can lead to unacceptable Quality of Service (QoS) and Quality of Experience (QoE) to users. In this work, we focus on a large variety of MPEG-4, H.264 and H.265-encoded video traces with different structural patterns. Different versions of each trace, in low, medium and high quality have been used in our study. We evaluated the accuracy of an existing video traffic prediction approach for the size of B-frames and tested some variants of it .We implemented the metaheuristic technique of Simulated Annealing to predict the size of B-frames, and compared the new results against an existing approach from the literature. We propose a new Markovian model that predicts B-frames’ sizes with significantly higher accuracy. B-frame size prediction can be used in order to reduce bandwidth requirements and smoothen the encoded video stream, by selective B-frame dropping, when the model predicts larger upcoming B-frame traffic than the network can handle.
title: Βέλτιστος έλεγχος για την διαχείριση δικτύου νερού, βασισμένος σε γενετικό αλγόριθμο
title: Operational optimal control of a water distribution network based on genetic algorithm
Creators: name: Ασμαργιαννακης Πετρος
Publisher: name: Technical University of Crete
Year: 2017

description: Despite wide research, design of water distribution networks is not realized using optimization techniques. The main reason for this assumption is that the design of water distribution networks is evaluated mostly, as a least cost optimization problem. Another parameter for preferring the traditional modelling practice is that, existing optimization algorithms are not presented to the user as friendly as it should be.
In this thesis we deal with the pump schedule optimization of water distribution systems. The aims and the possible applications of the presented method are significant and all of them are intended to solve a particular but realistic problem.
A genetic controller for a midscale water pumping station is developed in order to optimize the operation plan of the system for minimum energy consumption. A genetic algorithm, GA optimizer, is used to decide the operation plan of the pumps taking into account power consumption. Upper and lower limits of the water level in the tank is constrained by the GA.
The MATLAB Simscape blocks is used to build a full detailed model in a Simulink environment. The system consists of six pumps fed by a tank and deliver water to a buffer tank through the pipeline. This model is being processed many times to simulate, check and validate the behaviour of the system. Chania Vlite’s Pumping Station is taken as a case study. To optimize the operation plan of the system, the detailed model is used to design a preliminary control strategy which is used later to set the optimization problem. Fixed speed pump scheduling is found more efficient. The optimizer is tested and gave explainable results.
Finally, the case study is tested within 24 hour time horizon and an accepted operation plan has resulted. Detailed plots and charts are generated using MATLAB to explain what is going on through all the levels of work in this thesis. All detailed information about the operation of this pump station is from OAK AE.
On the Gaussian Interference Channel with Half-Duplex Causal Cognition
Creators: name: Cardone, Martina
name: Tuninetti, Daniela
name: Knopp, Raymond
name: Salim, Umer
Publisher: name: arXiv
Year: 2013
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: This paper studies the two-user Gaussian interference channel with half-duplex causal cognition. This channel model consists of two source-destination pairs sharing a common wireless channel. One of the sources, referred to as the cognitive, overhears the other source, referred to as the primary, through a noisy link and can therefore assist in sending the primary's data. Due to practical constraints, the cognitive source is assumed to work in half-duplex mode, that is, it cannot simultaneously transmit and receive. This model is more relevant for practical cognitive radio systems than the classical information theoretic cognitive channel model, where the cognitive source is assumed to have a non-causal knowledge of the primary's message. Different network topologies are considered, corresponding to different interference scenarios: (i) the interference-symmetric scenario, where both destinations are in the coverage area of the two sources and hence experience interference, and (ii) the interference-asymmetric scenario, where one destination does not suffer from interference. For each topology the sum-rate performance is studied by first deriving the generalized Degrees of Freedom (gDoF), or "sum-capacity pre-log" in the high-SNR regime, and then showing relatively simple coding schemes that achieve a sum-rate upper bound to within a constant number of bits for any SNR. Finally, the gDoF of the channel is compared to that of the non-cooperative interference channel and to that of the non-causal cognitive channel to identify the parameter regimes where half-duplex causal cognition is useless in practice or attains its ideal ultimate limit, respectively.
description: Accepted for publication in IEEE Journal on Selected Areas in Communications: Cognitive Radio Series