Seismic Evaluation of R/C Buildings Using High Performance Materials

The performance of reinforced concrete (R/C) buildings made of high performance materials (HPM) in seismic areas is evaluated through the parametric analysis of twenty-two buildings designed and detailed according to the current (prEN) version of Eurocode 8, for ductility classes (DC) \u27\u27Medium\u27\u27 and \u27\u27High\u27\u27, in combination with the current (prEN) version of Eurocode 2. Seismic assessment of the buildings is carried out by means of nonlinear static (pushover) analysis and nonlinear dynamic (time-history) analysis

STR-922: IMPACT OF SLENDERNESS ON THE SEISMIC RESPONSE OF ROCKING FRAMES IN ONTARIO NUCLEAR POWER PLANTS

Canadian Nuclear Power Plants (NPPs) are located on the eastern side of the North American continent, with the majority of them in Ontario. The Design Basis Earthquake (DBE), based on West Coast records, is prescribed in the Canadian nuclear standards. Seismic Probabilistic Risk Assessment studies of the existing plants consider time histories obtained from the latest research on the East Coast earthquakes as seismic input to the analysis. Although Canadian standards are silent about rocking response of unanchored objects, various industry guidelines and the standard ASCE 43-05 prescribe methodologies in this regard. Applications of a rocking frame in a NPP may vary from squat piers supporting a heavy rigid object to a slender masonry frame consisting of two concrete block walls and a rigid diaphragm on top. The methods of analysis prevalent in the nuclear industry recommend obtaining the response of an individual pier of a rocking frame, rather than an equivalent pier representing the rocking frame. Methods of obtaining an equivalent pier, whose response is the same as that of a rocking frame, have been detailed in the literature where it has been emphasized that rocking frames are more stable than an individual rocking pier. However, it is noticed that the response of rocking frames is influenced by their slenderness and also by the boundary condition at the contact between the piers and the top mass. The support boundary conditions are bounded by two extremes: the full top width of a pier, or a point support at its top center. This paper compares the equivalent block parameters of rocking frames for these two extreme boundary conditions. Also, it presents the seismic response of a slender rocking frame subjected to earthquake records compatible with the DBE spectra of Ontario NPPs, as well as spectra used in risk analysis

Multi-manifold Attention for Vision Transformers

Vision Transformers are very popular nowadays due to their state-of-the-art performance in several computer vision tasks, such as image classification and action recognition. Although their performance has been greatly enhanced through highly descriptive patch embeddings and hierarchical structures, there is still limited research on utilizing additional data representations so as to refine the selfattention map of a Transformer. To address this problem, a novel attention mechanism, called multi-manifold multihead attention, is proposed in this work to substitute the vanilla self-attention of a Transformer. The proposed mechanism models the input space in three distinct manifolds, namely Euclidean, Symmetric Positive Definite and Grassmann, thus leveraging different statistical and geometrical properties of the input for the computation of a highly descriptive attention map. In this way, the proposed attention mechanism can guide a Vision Transformer to become more attentive towards important appearance, color and texture features of an image, leading to improved classification and segmentation results, as shown by the experimental results on well-known datasets.Comment: This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

NDM-526: INVESTIGATION OF STABLE AND UNSTABLE FIBER-REINFORCED ELASTOMERIC ISOLATORS

Fiber-reinforced elastomeric isolators (FREIs) are a potentially low-cost alternative to conventional steel-reinforced elastomeric isolators. FREIs can exhibit a non-linear horizontal force-displacement relationship characterized by a softening and stiffening phase, similar to other adaptive isolation devices such as the triple friction pendulum. This non-linear relationship is a consequence of unique deformations that occur during horizontal displacement denoted as rollover, which causes softening, and full rollover, which causes stiffening. The magnitude of the softening due to rollover is primarily governed by the width-to-total height aspect ratio of the FREI. If the aspect ratio is low, below about 2.5, the isolator may be susceptible to horizontal instability where the tangential stiffness becomes negative before increasing due to full rollover. Design codes prevent the use of an isolation system susceptible to horizontal instability within the design displacement. In this paper, experimental testing is used to calibrate a numerical model of a base isolated structure using horizontally unstable and stable FREIs. The performance of the structure is evaluated based on peak displacement of the isolation layer and peak acceleration of the base isolated structure. For the isolators considered, it is shown that the horizontal instability does not have a negative impact on the performance of the structure. It is postulated that some level of horizontal instability may be allowed in the design of unbonded FREIs

The effect of Social Networking in Privacy Management

Diese Masterarbeit beschäftigt sich mit Privacy Management in Fragen der Online-Welt, die durch die rasche Entwicklung der Soziale-Netzwerke-Technologien entstehen. Die heutige Situation im Bereich der Sozial-Netzwerke-Gemeinden, zusammen mit den jeweiligen Gefahren in Bezug auf Privacy Wahrung werden gründlich untersucht und dargestellt. Spezifische Ziele werden ausgearbeitet, über die Richtung die Bemühungen der wissenschaftlichen Gemeinschaft in naher Zukunft nehmen sollten. Die organische Lücken des Privacy Management Gebietes werden thematisiert und analysiert, da sie die Ursachen für eine Vielzahl von problematischen Situationen bieten, die kontinuierlich die gesellschaftspolitische Frieden unserer Gesellschaften in den letzten paar Jahren erregt haben. Der Hauptteil dieser Arbeit beginnt mit der Identifizierung derjenigen Punkte, die eine de facto Lösung auf jeden Fall zu erfüllen muss, um die oben genannten Themen zu behandeln. Bewaffnet mit spezifischen Anforderungen, folgt eine Analyse durch die Wahl der theoretischen und praktischen Methoden. Ein Modell, dass den Spiel- Theoretischen Ansatz der kollektiven Privacy Management mit dem Konzept der Aneignung Konstrukt zu kombinieren versucht wird vorgeschlagen. Eine erweiterte Analyse erfolgt, über wie der Clarke-Tax-Mechanismus für das Kollaborative Management, verbindet mit dem Adaptive Strukturationstheorie, in Online-Datenschutz- Management verwendet werden können. Bevor man zu den Schlussfolgerungen und Reflexionen der Arbeit kommt gibt es ein Kapitel über die Grenzen des vorgeschlagenen Modells. Es ist offensichtlich, dass das Konzept nicht generisch ist. Nichts desto trotz sollte eine deutliche Präsentation warum nicht aus dieser Studie fehlen. Ein Wunsch, der zu dieser Masterarbeit beigefügt kommt, ist dass es mehr als ein Einführungsschritt der als akademischen Aufstieg eines jungen Mannes dienen wird. Es ist mit Hingabe an die Moralität die mit ihren Zielen zusammen kommt geschrieben, und damit den Wunsch, dass es gelesen wird und hoffentlich auch begrüßt.This MSc Thesis deals with Privacy Management issues in the online world that arise through the rapid evolution of Social Networking technologies. The current situation in the field of Social Networking communities, along with the respective dangers in regard to privacy safeguarding are thoroughly examined and presented. Specific goals are being set, as to the direction the efforts of the scientific community should take in the near future. An extended survey in the field of Privacy Management on Social Networking Sites is followed by an analysis on the missing parts of this already huge living organism. These organic gaps need to be addressed firmly, as they constitute natural causes for a multitude of problematic situations that have continuously stirred the sociopolitical peace of our societies for the past few years. The main part of this study starts with the identification of the singular points that any de facto solution is required to fulfill in order to address the issues mentioned above. Armed with specific requirements, an analysis is followed by a choice of theoretical and practical methods. A model that attempts to combine the game-theoretical approach of Collective Privacy Management with the concept of the Appropriation Construct is proposed. An extended analysis, on how the Clarke-Tax mechanism for collaborative management, conjoined with the Adaptive Structuration Theory, can be used in online privacy management, ensues. Before coming to the conclusions and reflections of our work, a chapter is dedicated to the limitations of the proposed model. It is obvious that the present approach is not generic; however, a more explicit presentation should not be absent from this study. The wish that comes attached to this MSc Thesis is that it will become more than a launching step to the academic advancement of a young man. It is written with faith and devotion to the morality that goes with its goals and thus, the wish that follows it is that it will be read and, hopefully, appreciated

Χρήση του Φάσματος Συχνοτήτων 70-500GHz στις δορυφορικές επικοινωνίες

Στα πλαίσια αυτής της διπλωματικής εργασίας έγινε μία προσπάθεια να επικεντρώσουμε το ενδιαφέρον μας στις συχνότητες που αφορούν τις δορυφορικές επικοινωνίες. Στο πρώτο κεφάλαιο γίνεται μία ιστορική αναδρομή στις δορυφορικές επικοινωνίες και σε θέματα που αφορούν τη δομή τους, την αρχιτεκτονική τους, τις τροχιές, τις υπηρεσίες και τις εφαρμογές τους. Στο δεύτερο κεφάλαιο γίνεται μία παρουσίαση των δορυφορικών επικοινωνιών με τη χρήση συχνοτήτων σε TeraHertz τιμές. Παράλληλα, αναφερόμαστε στα κίνητρα για τη χρήση των TeraHertz συχνοτήτων καθώς και στην ατμοσφαιρική απορρόφηση σε αυτές τις συχνότητες. Στο τρίτο κεφάλαιο αναφερόμαστε σε μήκη κύματος της τάξης των mm και στο μοντέλο καναλιού σε μήκη κύματος mm. Ταυτόχρονα, παρουσιάζονται δύο εφαρμογές γι’ αυτά τα μήκη κύματος (mmMAGIC Project και mmWave Backhaul και Fronthaul). Τέλος, στο τέταρτο κεφάλαιο εκθέτουμε μία σειρά από συμπεράσματα που αφορούν τη χρήση υπερυψηλών συχνοτήτων στις δορυφορικές επικοινωνίες.In the context of this dissertation, an attempt was made to focus our attention on the frequencies related to satellite communications. The first chapter provides a historical overview of satellite communications and issues related to their structure, architecture, trajectories, services and applications. The second chapter presents a presentation of satellite communications using frequencies in TeraHertz values. At the same time, we refer to the incentives for the use of TeraHertz frequencies as well as to the atmospheric absorption at these frequencies. In the third chapter we refer to wavelengths of the order of mm and to the channel model in wavelengths of mm. At the same time, two applications are presented for these wavelengths (mmMAGIC Project and mmWave Backhaul and Fronthaul). Finally, in the fourth chapter we present a series of conclusions regarding the use of high frequencies in satellite communications

Phase amplified correlation for improved sub-pixel motion estimation

Phase correlation (PC) is widely employed by several sub-pixel motion estimation techniques in an attempt to accurately and robustly detect the displacement between two images. To achieve sub-pixel accuracy, these techniques employ interpolation methods and function-fitting approaches on the cross-correlation function derived from the PC core. However, such motion estimation techniques still present a lower bound of accuracy that cannot be overcome. To allow room for further improvements, we propose in this paper the enhancement of the sub-pixel accuracy of motion estimation techniques by employing a completely different approach: the concept of motion magnification. To this end, we propose the novel phase amplified correlation (PAC) that integrates motion magnification between two compared images inside the phase correlation part of frequencybased motion estimation algorithms and thus directly substitutes the PC core. The experimentation on magnetic resonance (MR) images and real video sequences demonstrates the ability of the proposed PAC core to make subtle motions highly distinguishable and improve the sub-pixel accuracy of frequency-based motion estimation techniques

Preoperative tumor marking with indocyanine green prior of robotic colorectal resections

This prospective case-series study aimed to assess the usefulness of preoperative colonoscopic marking of colorectal tumors using Indocyanine Green (ICG) fluorescence in patients that underwent robotic surgical colorectal resections. Consecutive patients that were eligible for colorectal resection with intent to cure in a single hospital (Athens Medical Center), from February 2022 to June 2022, were included. ICG solution was injected into the submucosal layer at 2 opposite sites (180 degrees apart) distal to the tumor, without submucosal elevation. Identification of the tumor marking was then performed after switching to near-infrared (NIR) fluorescence mode. During the robotic procedure, qualitative evaluation of fluorescence was performed by the surgical team (primary surgeon, first assistant, second assistant, research fellow). All 10 patients underwent robotic surgical approach and operations included right-sided colectomy (n = 1), left-sided colectomy (n = 6) and low anterior resection (n = 3). Visualisation of this dye with near-infrared light was very clear with bright intensity in all patients when the marking was performed one day prior of surgery. Preoperative tumor marking with ICG was identified intraoperatively in all cases and the techinque was easily reproducible