Material aspects of underwater marine systems in Greece

The material selection for the improvement of the quality of already existing underwater marine systems (including oil platforms) and for the construction of new and unfamiliar underwater sea-structures (including the submerged parts of Wave Energy Converters and Tidal Energy Converters) in many countries like Greece is an essential parameter from a technical, qualitative and economical point of view. The purpose of this review paper is to present a justified analysis of the proposed materials, explaining in more details the advantages of their properties and focusing on the applicable welding issues taking into consideration the previous existing experience from shipbuilding and submarine constructions

Multidisciplinary shallow underwater geophysical prospecting at Delos island

Geophysical imaging methods have been applied to reconstruct the cultural dynamics in the two different submerged sites in Delos island. The geophysical results provided useful information for understanding the complexity of the submerged archaeological sites

Συγκριτική έρευνα ψηφιακών συστημάτων διαχείρισης συλλογών και εφαρμογή στο Μουσείο Πληροφορικής & Τηλεπικοινωνιών ΕΚΠΑ

Η παρούσα πτυχιακή εργασία επικεντρώνεται στην ανάπτυξη ενός συστήματος διαχείρισης συλλογών για το Μουσείο Πληροφορικής και Τηλεπικοινωνιών του Εθνικού και Καποδιστριακού Πανεπιστημίου Αθηνών. Στόχος είναι η ανάπτυξη ενός λειτουργικού συστήματος που θα βοηθήσει τους διαχειριστές του μουσείου να καταγράφουν και να παρουσιάζουν τις συλλογές του με τον καλύτερο δυνατό τρόπο. Η εργασία αυτή περιλαμβάνει μια επισκόπηση εργαλείων διαχείρισης συλλογών όπως το DSpace, το Collective Access, το CKAN και το Omeka S, καθώς και τη σύγκρισή τους για τη καλύτερη κατανόηση των κριτηρίων επιλογής του συστήματος που χρησιμοποιήθηκε για τη διαχείριση της συλλογής του Μουσείου. Περιγράφονται οι προδιαγραφές που τεθηκαν για το σύστημα αυτό, οι βασικότερες ομάδες χρηστών που θα το χρησιμοποιήσουν και γίνεται η επιλογή του εργαλείου που καλύπτει καλύτερα τις ανάγκες του μουσείου. Στην συνέχεια, αναπτύσσονται τα μοντέλα καταγραφής των εκθεμάτων για τη προβολή και αποθήκευση της πληροφορίας μέσα στο σύστημα και περιγράφεται η υλοποίησή του. Γίνεται μια περιγραφή της λειτουργίας του και δημιουργείται ένα σενάριο χρήσης της εφαρμογής με τις βασικότερες ενέργειες μέσα σε αυτή. Τέλος, παρουσιάζεται η διαδικασία αξιολόγησής του από επιλεγμένους χρήστες, προβάλλονται τα αποτελέσματα και τα συμπεράσματα αυτής και καταγράφονται κάποιες βελτιώσεις και μελλοντικές επεκτάσεις για το σύστημαThis thesis focuses on the development of a collection management system for the Museum of Informatics and Telecommunications (MI&T) of the National and Kapodistrian University of Athens. The goal is to develop a functional system that will help museum administrators to record and present their collections in the best possible way. This work includes an overview of collection management tools such as DSpace, Collective Access, CKAN, and Omeka S, as well as their comparison for better understanding. The specifications set for this system, the main user groups that will use it, and the selection of the tool that best meets the museum's needs are described. Subsequently, object recording models are developed for displaying and storing information within the system, and their implementation is described. Presentation of the system's functionality, and a usage scenario of the application is created with the basic actions performed within it. Finally, the evaluation by users is conducted, and the results and conclusions are presented, along with some improvements and future extensions for the system

Impact of drone route geometry on information collection in wireless sensor networks

The recent technological evolution of drones along with the constantly growing maturity of its commercialization, has led to the emergence of novel drone-based applications within the field of wireless sensor networks for information collection purposes. In such settings, especially when deployed in outdoor environments with limited external control, energy consumption and robustness are challenging problems for the system’s operation. In the present paper, a drone-assisted wireless sensor network is studied, the aim being to coordinate the routing of information (among the ground nodes and its propagation to the drone), investigating several drone trajectories or route shapes and examining their impact on information collection (the aim being to minimize transmissions and consequently, energy consumption). The main contribution lies on the proposed algorithms that coordinate the communication between (terrestrial) sensor nodes and the drone that may follow different route shapes. It is shown through simulations using soft random geometric graphs that the number of transmitted messages for each drone route shape depends on the rotational symmetry around the center of each shape. An interesting result is that the higher the order of symmetry, the lower the number of transmitted messages for data collection. Contrary, for those cases that the order of symmetry is the same, even for different route shapes, similar number of messages is transmitted. In addition to the simulation results, an experimental demonstration, using spatial data from grit bin locations, further validates the proposed solution under real-world conditions, demonstrating the applicability of the proposed approach.publishedVersio

Underwater geophysical prospection in ancient Olous, Crete

We employ electrical resistivity tomography and magnetic gradiometry methods to the ultra-shallow submerged and littoral archaeological site of Olous. This allows reconstruction of the built environment that nowadays lie below the sea bottom, thus completing the respective archaeological evidence

Gerontechnology: Providing a Helping Hand When Caring for Cognitively Impaired Older Adults—Intermediate Results from a Controlled Study on the Satisfaction and Acceptance of Informal Caregivers

The incidence of cognitive impairment in older age is increasing, as is the number of cognitively impaired older adults living in their own homes. Due to lack of social care resources for these adults and their desires to remain in their own homes and live as independently as possible, research shows that the current standard care provisions are inadequate. Promising opportunities exist in using home assistive technology services to foster healthy aging and to realize the unmet needs of these groups of citizens in a user-centered manner. ISISEMD project has designed, implemented, verified, and assessed an assistive technology platform of personalized home care (telecare) for the elderly with cognitive impairments and their caregivers by offering intelligent home support services. Regions from four European countries have carried out long-term pilot-controlled study in real-life conditions. This paper presents the outcomes from intermediate evaluations pertaining to user satisfaction with the system, acceptance of the technology and the services, and quality of life outcomes as a result of utilizing the services

Imaging performance of a CaWO4/CMOS sensor

The aim of this study was to investigate the modulation transfer function (MTF) and the effective gain transfer function (eGTF) of a non-destruc­­tive testing (NDT)/industrial inspection complementary metal oxide semi­conductor (CMOS) sensor in conjunction with a thin calcium tungstate (CaWO4) screen. Thin screen samples, with dimensions of 2.7x3.6 cm2 and thick­ness of 118.9 μm, estimated from scanning electron microscopy-SEM im­ages, were extracted from an Agfa Curix universal screen and coupled to the active area of an active pixel (APS) CMOS sensor. MTF was assessed using the slanted-edge method, following the IEC 62220-1-1:2015 method. MTF values were found high across the examined spatial frequency range. eGTF was found maximum when CaWO4 was combined with charge-coupled devices (CCD) of broadband anti-reflection (AR) coating (17.52 at 0 cycles/mm). The com­bi­nation of the thin CaWO4 screen with the CMOS sensor provided very pro­mis­ing image resolution and adequate efficiency properties, thus could be also con­sidered for use in CMOS based X-ray imaging devices, for various applications

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701

Satellite Derived Bathymetry (SDB) and Safety of Navigation

This paper reviews the use of Satellite Derived Bathymetry (SDB) technology to derive depths from remote sensed (RS) data and how this technology can be used to address crucial aspects of safety of navigation. The estimation of bathymetric depth using optical RS techniques has advantages and disadvantages. Using imagery techniques, depths can be determined quickly over large remote coastal areas. These areas can however consist of dangerous hazards, submerged objects and steep seabed morphology. SDB processing techniques introduces new perspectives to potentially improving safety of navigation charting. The feasibility of deriving bathymetry from remote sensed images, requires that the accuracy of such data should be evaluated and an assessed in terms of how this data can be used and depicted in nautical chart production. The parameters associated with SDB capabilities that contribute to cartographic production are further discussed and evaluated against current IHO Standards.Este artículo revisa el uso de la tecnología de Batimetría Satelital Derivada (SDB) para obtener profundidades a partir de datos obtenidos de sensores remotos (RS) y cómo esta tecnología puede utilizarse para abordar aspectos cruciales de la seguridad de la navegación. La estimación de la profundidad batimétrica utilizando técnicas ópticas RS tiene ventajas y desventajas. Usando técnicas de imágenes, las profundidades pueden determinarse rápidamente en extensas áreas costeras remotas. Sin embargo, estas áreas pueden contener amenazas peligrosas, objetos sumergidos y en una morfología escarpada del fondo marino. Las técnicas de procesado SDB introducen nuevas perspectivas para mejorar potencialmente la representación de la seguridad de la navegación. La viabilidad de la derivación de la batimetría a partir de imágenes obtenidas de sensores remotos requiere que la exactitud de tales datos sea evaluada y valorada en términos de cómo estos datos pueden utilizarse y representarse en la producción de cartas náuticas. Los parámetros asociados a las capacidades SDB que contribuyen a la producción cartográfica se discuten adicionalmente y se evalúan conforme a las normas actuales de la OHI.Cet article étudie l'utilisation de la technologie de la bathymétrie par satellite (SDB) afin de déduire des profondeurs à partir de données de télédétection (RS) ainsi que la manière dont cette technologie peut être utilisée pour traiter des aspects cruciaux de la sécurité de la navigation. L'estimation de la profondeur bathymétrique à l'aide de techniques de télédétection optique présente des avantages et des inconvénients. En utilisant des techniques d'imagerie, les profondeurs peuvent être déterminées rapidement sur de vastes zones côtières lointaines. Ces zones peuvent néanmoins contenir des risques dangereux, des objets immergés et comporter des fonds marins escarpés. Les techniques de traitement de la SDB introduisent de nouvelles perspectives pour une éventuelle amélioration de la cartographie pour les besoins de la sécurité de la navigation. La possibilité de dériver la bathymétrie à partir d'images de télédétection nécessite que la précision de ces données soit évaluée et analysée afin de savoir comment elles peuvent être utilisées et décrites dans la production de cartes marines. Les paramètres associés aux capacités de la SDB qui contribuent à la production cartographique font l'objet de discussions plus poussées et sont évalués par rapport aux normes de l'OHI en vigueur