Self-healing of Structural Composites Containing Dendrimers as Healing Agent

Dendrimers exhibit healing functionalities on polymer level. In the present chapter, the effect of hydrogen-bonded supramolecular polymers (SP) into high performance aerospace carbon fiber reinforced plastics (CFRPs) is assessed. More precisely, the interlaminar fracture toughness of unidirectional (UD) SP-modified composites (containing SP interleaves) and their healing capability were measured under mode I and mode II fracture loading conditions. During testing, these modified samples exhibited extended bridging between the interlaminar crack flanks, which considerably enhanced their interlaminar fracture toughness. Furthermore, SP pre-impregnated fiber layers (prepregs) were fabricated to facilitate the introduction of the self-healing agent (SHA) into the composite laminated structure. SP prepregs were used to modify quasi-isotropic CFRPs in a symmetric fashion, and the damage tolerance of the modified composites was investigated. To that direction, the SP-modified laminates were tested under low velocity impact (LVI) conditions, and compression after impact (CAI) tests were conducted prior and after the activation of the healing. Finally, examination of the morphology of fracture surface led to qualitative conclusions regarding the involved failure and healing mechanisms

A Survey on Small Satellite Technologies and Space Missions for Geodetic Applications

Advances in microelectronics, materials, combined with affordable and frequent launch opportunities has led to a revolution which consists of small satellite missions used for technology validation, Earth observation, space exploration. Small satellites are now being developed in large volumes for mega-constellations for Earth observation, Internet of Things (IoT) and low latency communications (internet) thus democratizing space and making new space applications a reality. Advances in small satellite platforms, miniaturization of instruments and the availability of low-cost launches for small satellites, can enable new, geodetic missions which can benefit from the use of constellations of small satellites. An overview of some of the most important small satellite based geodetic missions is presented, along with a brief overview of new mission concepts which can significantly enhance our knowledge in the geodetic field

Autonomous unmanned heterogeneous vehicles for persistent monitoring

Swarms of unmanned vehicles (air and ground) can increase the efficiency and effectiveness of military and law enforcement operations by enhancing situational awareness and allowing the persistent monitoring of multiple hostile targets. The key focus in the development of the enabling technologies for swarm systems is the minimisation of uncertainties in situational awareness information for surveillance operations supported by ‘system of systems’ composed of static and mobile heterogeneous sensors. The identified critical enabling techniques and technologies for adaptive, informative and reconfigurable operations of unmanned swarm systems are robust static sensor network design, mobile sensor tasking (including re-allocation), sensor fusion and information fusion, including behaviour monitoring. The work presented in this paper describes one of the first attempts to integrate all swarm-related technologies into a prototype, demonstrating the benefits of swarms of heterogeneous vehicles for defence applications used for the persistent monitoring of high-value assets, such as military installations and camps. The key enabling swarm system technologies are analysed here, and novel algorithms are presented that can be implemented in available COTS-based unmanned vehicles. The algorithms have been designed and optimised to require small computational power, be flexible, be reconfigurable and be implemented in a large range of commercially available unmanned vehicles (air and ground).European Defence Agency: PP-15-INR-0

Autonomous inspection and repair of aircraft composite structures

This paper deals with the development of an innovative approach for inspection and repair of damage in aeronautical composites that took place in the first two years of the H2020 CompInnova project which. The aim is a newly designed robotic platform for autonomous inspection using combined infrared thermography (IRT) and phased array (PA) non-destructive investigation for damage detection and characterization, while integrated with laser repair capabilities. This will affect the increasing societal need for safer aircraft in the lowest possible cost, while new and effective techniques of inspection are needed because of the rapidly expanding use of composites in the aerospace industry

EuroDRONE, A European unmanned traffic management testbed for U-space

EuroDRONE is an Unmanned Traffic Management (UTM) demonstration project, funded by the EU’s SESAR organization, and its aim is to test and validate key UTM technologies for Europe’s ‘U-Space’ UTM program. The EuroDRONE UTM architecture comprises cloud software (DroNav) and hardware (transponder) to be installed on drones. The proposed EuroDRONE system is a Highly Automated Air Traffic Management System for small UAVs operating at low altitudes. It is a sophisticated, self-learning system based on software and hardware elements, operating in a distributed computing environment, offering multiple levels of redundancy, fail-safe algorithms for conflict prevention/resolution and assets management. EuroDRONE focuses its work on functionalities which involve the use of new communication links, the use of vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2V) technology to communicate information between drones and operators for safe and effective UTM functionality. Practical demonstrations that took place in Patras/Messolonghi in 2019 are presented and show the benefits and shortcomings of near-term UTM implementation in Europe

Chapter Self-healing of Structural Composites Containing Dendrimers as Healing Agent

Dendrimers exhibit healing functionalities on polymer level. In the present chapter, the effect of hydrogen-bonded supramolecular polymers (SP) into high performance aerospace carbon fiber reinforced plastics (CFRPs) is assessed. More precisely, the interlaminar fracture toughness of unidirectional (UD) SP-modified composites (containing SP interleaves) and their healing capability were measured under mode I and mode II fracture loading conditions. During testing, these modified samples exhibited extended bridging between the interlaminar crack flanks, which considerably enhanced their interlaminar fracture toughness. Furthermore, SP pre-impregnated fiber layers (prepregs) were fabricated to facilitate the introduction of the self-healing agent (SHA) into the composite laminated structure. SP prepregs were used to modify quasi-isotropic CFRPs in a symmetric fashion, and the damage tolerance of the modified composites was investigated. To that direction, the SP-modified laminates were tested under low velocity impact (LVI) conditions, and compression after impact (CAI) tests were conducted prior and after the activation of the healing. Finally, examination of the morphology of fracture surface led to qualitative conclusions regarding the involved failure and healing mechanisms

Parameterization of the coefficients for momentum, heat and humidity turbulent fluxes within the surface Marine Atmospheric Boundary Layer and implementation in an atmospheric or/and an oceanographic model

The main objectives of this thesis are (a) the experimental study of the turbulent fluxes of momentum, heat and humidity within the surface Marine Atmospheric Boundary Layer (MABL) over the Aegean Sea in the Eastern Mediterranean and (b) the impact from the implementation of a new parameterization of the drag coefficient (CD) for the momentum flux on the estimation of the sea surface temperature (SST) forecast skill of the oceanographic model ALERMO (Aegean and Levantine Eddy Resolving Model) over this area.This thesis highlights the following facts: (a) heat exchanges were found to be affected by the limited spatial and temporal scales of the responding air-sea interaction mechanism over the Aegean Sea. (b) increased momentum fluxes were found over the Aegean under moderate to strong winds (c) the SST forecast skill of the ALERMO ocean model over the Eastern Mediterranean was affected from the change in momentum transfer at the air-sea interface using an observational based parameterization for the drag coefficient; improved forecasts were found during spring and the opposite during summer (d) further investigation of coastal processes and the oceanic response to intense wind forcing in shallow areas is needed along with (e) additional turbulence measurements within the surface MABL over the Aegean Sea, under wider range of wind speed, stability and sea wave conditions.Οι βασικοί στόχοι της παρούσας διατριβής υπήρξαν (α) η πειραματική μελέτη των τυρβωδών ροών ορμής, θερμότητας και υγρασίας στο επιφανειακό Θαλάσσιο Ατμοσφαιρικό Οριακό Στρώμα (ΘΑΟΣ) πάνω από την θάλασσα του Αιγαίου και (β) η αξιολόγηση μιας προκύπτουσας παραμετροποίησης για τη ροή ορμής, μέσω του συντελεστή αεροδυναμκής αντίστασης (CD), με την εφαρμογή της στο ωκεανογραφικό μοντέλο ALERMO και την σύγκριση των προγνώσεων για την επιφανειακή θερμοκρασία της θάλασσας με δορυφορικές παρατηρήσεις στην ευρύτερη περιοχή της ανατολικής Μεσογείου.Η διατριβή αυτή ανέδειξε συνολικά ότι: (α) οι ανταλλαγές θερμότητας επηρεάζονται από την σχετικά μικρή χωροχρονική κλίμακα αλληλεπίδρασης μεταξύ ατμόσφιρας και θάλασσας πάνω από το Αιγαίο (β) καταγράφησαν υψηλές τιμές ροής ορμής κάτω από μέτριους έως ισχυρούς ανέμους στην περιοχή (γ) η προγνωστική ικανότητα του μοντέλου θαλάσσιας κυκλοφορίας ALERMO σχετικά με την επιφανειακή θερμοκρασία της θάλασσας, επηρεάστηκε από την εφαρμογή της νέας παραμετροποίησης του συντελεστή αεροδυναμικής αντίστασης και προέκυψε βελτίωση των προγνώσεων τοπικά έως και 25% την άνοιξη και το αντίθετο το καλοκαίρι. Τέλος σημειώνεται ότι θεωρείται αναγκαία περαιτέρω διευρέυνηση των διαδικασιών ανάβλησης καθώς και της επίδρασης της τάσης του ανέμου σε παράκτιες περιοχές καθώς και πραγματοποίηση περισσότερων μετρήσεων των τυρβωδών ροών πάνω από το Αιγαίο, υπό μεγαλύτερο εύρος ταχύτητας του ανέμου, ευστάθειας της ατμόσφαιρας και κατάστασης κυματισμού της θαλάσσιας επιφάνειας