A Multi-Element Detector System for Intelligent Imaging: I-ImaS

I-ImaS is a European project aiming to produce new, intelligent x-ray imaging systems using novel APS sensors to create optimal diagnostic images. Initial systems concentrate on mammography and encephalography. Later development will yield systems for other types of radiography such as industrial QA and homeland security. The I-ImaS system intelligence, due to APS technology and FPGAs, allows real-time analysis of data during image acquisition, giving the capability to build a truly adaptive imaging system with the potential to create images with maximum diagnostic information within given dose constraints. A companion paper deals with the DAQ system and preliminary characterization. This paper considers the laboratory x-ray characterization of the detector elements of the I-ImaS system. The characterization of the sensors when tiled to form a strip detector will be discussed, along with the appropriate correction techniques formulated to take into account the misalignments between individual sensors within the array. Preliminary results show that the detectors have sufficient performance to be used successfully in the initial mammographic and encephalographic I-ImaS systems under construction and this paper will further discuss the testing of these systems and the iterative processes used for intelligence upgrade in order to obtain the optimal algorithms and setting

Research and assessment of remote experiments in physics education using wireless networks

The global literature often refers to the effectiveness of experimentation in physics education in terms of building students’ awareness towards a deeper understanding of the teaching concepts. The development of educational experiments constitutes a complex process since researchers should be familiar with the relevant literature in order to make a proper selection of the teaching object (that would be addressed in the laboratory course), while also applying innovations in education and engineering disciplines. In the latter case, the development and implementation of the educational equipment should be directed with systematic attention in order facilitate the conduction of experiments as well as promote students’ learning process.Several paradigms of remotely accessed educational equipments can be found in the abundant literature, which are addressed to improve traditional experimentation practices. Advantages of remote experimentation are not only limited to the possibility of studying by distance. They are also extended to the possibility of remotely accessing the experimentation equipment during the presence of students in the classroom; thereby reducing the overall cost of laboratory equipment. The present thesis applies to the development, implementation and evaluation of innovative educational equipment that supports remote access to physical quantities, particularly to atmospheric pressure measurements, using network/internet topology. Implementation of the educational equipment is based on the development of a wireless sensor network system that employs MEMS technology and applies to barometric altimetry.Micro-Electro-Mechanical-Systems (MEMS) constitute a cutting-edge technology of small package, reduced cost and low consumption features. The MEMS technology integrates a mechanical component, which produces electric signal proportional to the changes applied to the mechanical element. Due to the interdisciplinary nature of MEMS (i.e., materials science, control systems, sensors, design and fabrication of integrated systems, etc.), this technology has brought new trends in industrial automation while also affected education who now meets several curricula orientated to the study of MEMS.Following a literature review in remote experimentation in Physics education and then summarizing the prevalent methods of implementing equipments for remote monitoring of physical quantities, the present doctoral thesis initially performed an evaluation of the measurements and methodologies used in barometric altimetry. Thereafter, the proposed educational physics experiments and their effects on the students’ learning process were assessed. An alternative implementation of the prototype equipment in support of laboratory education for individuals with physical disabilities was also proposed in the literature. Finally, the possibilities offered by modern digital technologies in experimental teaching of physics, as well as the interdisciplinary research required to implement innovative laboratory experiments in a field still being under investigation by the scientific community, were also evaluated.Στη διεθνή βιβλιογραφία γίνεται συχνά λόγος για την ανεκτίμητη αξία του πειράματος στη διδασκαλία της Φυσικής, όσον αφορά την οικοδόμηση αντίληψης των διδασκομένων για τη βαθύτερη κατανόηση των φυσικών εννοιών. Η ανάπτυξη εκπαιδευτικών πειραμάτων αποτελεί μία πολύπλοκη διεργασία, καθότι ο ερευνητής θα πρέπει γνωρίζει πολύ καλά τη διεθνή βιβλιογραφία ώστε να προβεί σε δόκιμη επιλογή του αντικειμένου διδασκαλίας που πρόκειται να εισάγει στο εργαστήριο, εφαρμόζοντας καινοτομίες τόσο σε εκπαιδευτικό επίπεδο, όσο και σε επίπεδο μηχανικής. Στη δεύτερη περίπτωση, η ανάπτυξη και υλοποίηση του εκπαιδευτικού εξοπλισμού θα πρέπει να διασφαλίζει την ορθή λειτουργία και ομαλή διεξαγωγή του πειράματος, καθώς και να προωθεί τη διαδικασία εκμάθησης του γνωστικού αντικειμένου στους διδασκόμενους.Στη διεθνή βιβλιογραφία συναντώνται αρκετά παραδείγματα υλοποίησης εξοπλισμού απομακρυσμένης πρόσβασης σε εκπαιδευτικά πειράματα, τα οποία προορίζονται να συμπληρώσουν τις αδυναμίες του παραδοσιακού πειραματισμού. Τα πλεονεκτήματα του εξ αποστάσεως πειραματισμού δεν περιορίζονται μόνο στη δυνατότητα μελέτης από απόσταση, επεκτείνονται και στη δυνατότητα του εξ αποστάσεως ελέγχου πειραμάτων κατά τη διάρκεια παρουσίας των διδασκομένων στην τάξη, μέσω του δικτύου/διαδικτύου λόγου χάριν, μειώνοντας σημαντικά το κόστος εργαστηριακού εξοπλισμού. Στην παρούσα διδακτορική διατριβή πραγματοποιήθηκε ανάπτυξη, υλοποίηση και αξιολόγηση καινοτόμου εκπαιδευτικού εξοπλισμού που υποστηρίζει την εξ αποστάσεως πρόσβαση σε μετρήσεις Φυσικών μεγεθών και συγκεκριμένα ατμοσφαιρικής πίεσης, με τη χρήση του δικτύου/διαδικτύου. Η υλοποίηση του εξοπλισμού βασίστηκε στην ανάπτυξη ασύρματου δικτυού αισθητήρων τεχνολογίας MEMS και έχει εφαρμογή στη βαρομετρική υψομετρία.Τα Μικρο-Ηλεκτρομηχανικά Συστήματα (Micro-Electromechanical Systems – MEMS) αποτελούν τεχνολογία αιχμής, η οποία φέρει τα χαρακτηριστικά μικρής συσκευασίας, χαμηλού κόστους και κατανάλωσης. Η τεχνολογία MEMS ενσωματώνει μία μηχανική λειτουργία, στην αλλαγή της οποίας παράγεται ηλεκτρικό σήμα. Λόγω της διεπιστημονικής φύσης των MEMS (επιστήμη των υλικών, συστήματα ελέγχου, αισθητήρες, σχεδιασμός ολοκληρωμένων συστημάτων, κ.ά.), η τεχνολογία αυτή έχει επιφέρει νέα αναπτυξιακή δυναμική στο βιομηχανικό αυτοματισμό και έχει επηρεάσει σημαντικά και την εκπαίδευση, όπου πλέον συναντώνται αρκετά περιγράμματα σπουδών με αντικείμενο μελέτης τα MEMS.Ακολουθώντας μια βιβλιογραφική ανασκόπηση στα πειράματα Φυσικής από απόσταση και κατόπιν συνοψίζοντας τους επικρατέστερους τρόπους υλοποίησης εξοπλισμού για την εξ αποστάσεως συλλογή Φυσικών μεγεθών, στα πλαίσια της διδακτορικής διατριβής πραγματοποιήθηκε αρχικά αξιολόγηση των μετρήσεων και μεθοδολογιών που χρησιμοποιούνται στη βαρομετρική υψομετρία με τη χρήση του πρωτότυπου ερευνητικού εξοπλισμού. Εν συνέχεια, πραγματοποιήθηκε αποτίμηση των προτεινόμενων εκπαιδευτικών πειραμάτων Φυσικής και του αντίκτυπου αυτών στην εκμάθηση των φοιτητών. Επίσης προτάθηκε μία εναλλακτική μορφή υλοποίησης του παρόντος εξοπλισμού για την υποστήριξη της εργαστηριακής εκπαίδευσης ατόμων με κινητική αναπηρία. Τέλος, αποτιμήθηκαν οι δυνατότητες που προσφέρουν οι σύγχρονες ψηφιακές τεχνολογίες στην πειραματική διδασκαλία της Φυσικής, καθώς και η διεπιστημονική έρευνα που απαιτείται για την υλοποίηση καινοτόμων πειραμάτων εργαστηριακής εκπαίδευσης σε ένα πεδίο που βρίσκεται ακόμη υπό διερεύνηση από την επιστημονική κοινότητα

First record of Chlorophorus herbstii (Brahm, 1790) in Greece and new localities of Xylosteus bartoni Obenberger & Mařan, 1933 (Coleoptera, Cerambycidae)

In this study, Chlorophorus herbstii (Coleoptera, Cerambycidae) was reported for the first time for Greek fauna. Another longhorn beetle, Xylosteus bartoni, has been found in two new localities in the country.&nbsp

New and noteworthy records of saproxylic beetles (Coleoptera) from Crete (Greece)

Saproxylic beetles are in the spotlight of conservation biology. Crete (Greece) constitutes a special biogeographical entity and an endemism hotspot for many organisms. Despite its poor forest coverage and the continuous degradation of Cretan forests by human activities, Crete hosts an impressive assemblage of saproxylic Coleoptera, some of them being endemic of the island or/and threatened under the I.U.C.N. criteria. Herein we present new data regarding several saproxylic Coleoptera species of Crete, reporting the first records of five species for the Cretan entomofauna [Calais parreysii (Steven, 1829), Dorcus parallelipipedus (Linnaeus, 1758), Dorcus peyronis Reiche and Saulcy, 1856, Platypus cylindrus (Fabricius, 1792) and Echinocerus floralis (Pallas, 1773)]

Finite element-based assessment of energy harvesting in composite beams with piezoelectric transducers

A finite element-based methodology is introduced for studying composite beams with piezoelectric transducers connected to energy harvesting circuits. Continuous and lumped-parameter models are developed based on finite element approximations and verified by means of experiments performed on a cantilever beam subjected to sinusoidal excitation at low, with respect to resonance, frequencies below 15 Hz. Three harvesting circuits have been studied: an in-house, a commercial, modified to include a rectification stage, and an off-the-shelf commercial. Comparison of numerical predictions with experiments illustrates good agreement in voltage and high sensitivity to current losses in the circuit. It was found that the commercial circuits outperform the in-house circuit in terms of harvested power at frequencies higher than 5 Hz, while the latter enables power harvesting at arbitrary low frequencies. Based on these results, it is demonstrated that the developed approach enables coupled simulation of a composite structure and a realistic harvesting circuit in one-shot. © IMechE 2021

Automating Loading and Locking of New Generation Air-cargo Containers

In this paper, an outline of NTUA’s work in the framework of project INTELLICONT is presented. We describe the current state of the air-cargo handling procedures and how the autonomous system that is under development is going to simplify these and increase the overall efficiency. Important issues and challenges regarding the system's development are discussed and a preliminary design of the novel robotic platform is given. The main tasks of this platform include the autonomous motion and locking of containers with mass exceeding one tone, avoiding at the same time obstacles and surpassing terrain discontinuities. Information regarding the selected actuators and other key electrical components, such as motor drivers and sensors are provided also. The architecture of the embedded system and the specifications of the selected Central Control Unit are described, as well as the integration of the motor drivers, sensors and other peripherals with the Robot Operating System (ROS). Further details on the development of a high accuracy localization system, which is mandatory to lock the container safely to the corresponding positions are provided also. In addition, we give details regarding the locking mechanism with integrated monitoring functionalities, an important part of the system. Simulation experiments validate the selected position controller and key system specifications are highlighted based on results. Finally, recent prototype experiments conducted to verify the localization system are presented