Gallium and titanium diffused optical waveguide devices in sapphire

This thesis describes new methods to realise an integrated Ti:Sapphire laser using thermal ionic diffusion. Passive and active waveguides were fabricated by thermal diffusion of gallium and titanium ions in sapphire.Theoretical simulations were established which describe the potential of planar Ti:Sapphire waveguide lasers and intracavity wavelength selection devices. A diffusion study of gallium, titanium and gallium/titanium co-doping is presented; the diffusion coefficient of gallium ions in sapphire was calculated to be 3.3x10-17 m2s-1 at 16000 °C and the diffusion coefficient of titanium ions in sapphire at 16000 °C was found to be 1.7x10-15 m2s-1. Planar Ga:Sapphire passive waveguides were realised by thermal diffusion of gallium ions. The refractive index of sapphire at 800nm is approximately 1.766 and the index change induced by gallium doping was found to be up to 6x10-3 and the mode sizes of the waveguides were as small as 1µm at 488nm. A fabrication procedure based on SU-8 photolithography and ion beam milling was developed for micromachining the surface of sapphire. Using this fabrication technique Ga:Sapphire ridge waveguides were fabricated by diffusion of gallium and exhibited mode sizes as small as 2µm at 633nm. Using the same fabrication technique the realisation of the first Ti-diffused sapphire ridge waveguide lasers is reported. Finally, the fabrication of sapphire optical circuits using titanium and gallium co-doping is described and fluorescence characterisation of these waveguides is given

Resurrecting anti-virtualization and anti-debugging: Unhooking your hooks

Dynamic malware analysis involves the debugging of the associated binary files and the monitoring of changes in sandboxed environments. This allows the investigator to manipulate the code execution path and environment to develop an understanding of the malware’s internal workings, aims and modus operandi. However, the latest state of the art malware may incor- porate anti-virtual environment (VM) and anti-debugging countermeasures (i.e. to determine whether the malware is being executed in a VM or us- ing a debugger prior to payload execution). We argue that for the malware to be effective, it will need to support an array of anti-detection and eva- sion mechanisms. In essence, from the malware’s perspective, it needs to adopt a “defence in depth” paradigm to achieve its underlying business logic functionality. Beyond the malicious uses, software vendors to preserve the intellectual property rights of their products often resort to similar methods to deter competitors from gaining intelligence from the binaries or prevent customers from using their products in unauthorised hardware. In this work, we illustrate how Windows architecture impedes the work of debuggers when they analyse with armoured binaries. The debugger and the malware have the same privileges, so the attacker may manipulate theaddress space that the debugger operates and, e.g. bypass detection. We showcase this by presenting a new framework (ANTI), which automates the procedure of integrating anti-debugging and anti-VM in the binary. Specifi- cally, ANTI introduces an anti-hooking method targeting Windows binaries, where hooks applied by state of the art debuggers are removed and injects its code in other processes. This significantly compounds the challenge of binary analysis. Our extensive evaluation also demonstrates that ANTI successfully circumvents detection from state-of-the-art detection methods. Therefore, ANTI illustrates that current tools for dynamic analysis have serious implementation gaps that allow for binaries to bypass them. More alarmingly, ANTI shows how one can use well-known methods to “resurrect” old attacks

175 GHz, 400-fs-pulse harmonically mode-locked surface emitting semiconductor laser

We report a harmonically mode-locked vertical external cavity surface emitting laser (VECSEL) producing 400 fs pulses at a repetition frequency of 175 GHz with an average output power of 300 mW. Harmonic mode-locking was established using a 300 µm thick intracavity single crystal diamond heat spreader in thermal contact with the front surface of the gain sample using liquid capillary bonding. The repetition frequency was set by the diamond microcavity and stable harmonic mode locking was achieved when the laser cavity length was tuned so that the laser operated on the 117th harmonic of the fundamental cavity. When an etalon placed intracavity next to the gain sample, but not in thermal contact was used pulse groups were observed. These contained 300 fs pulses with a spacing of 5.9 ps. We conclude that to achieve stable harmonic mode locking at repetition frequencies in the 100s of GHz range in a VECSEL there is a threshold pulse energy above which harmonic mode locking is achieved and below which groups of pulses are observed

Simulation of metallic nanostructures for emission of THz radiation using the lateral photo-Dember effect

A 2D simulation for the lateral photo-Dember effect is used to calculate the THz emission of metallic nanostructures due to ultrafast diffusion of carriers in order to realize a series of THz emitters.Comment: Corrected version of a paper given at 2011 36th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz

Unpublished Mediterranean and Black Sea records of marine alien, cryptogenic, and neonative species

To enrich spatio-temporal information on the distribution of alien, cryptogenic, and neonative species in the Mediterranean and the Black Sea, a collective effort by 173 marine scientists was made to provide unpublished records and make them open access to the scientific community. Through this effort, we collected and harmonized a dataset of 12,649 records. It includes 247 taxa, of which 217 are Animalia, 25 Plantae and 5 Chromista, from 23 countries surrounding the Mediterranean and the Black Sea. Chordata was the most abundant taxonomic group, followed by Arthropoda, Mollusca, and Annelida. In terms of species records, Siganus luridus, Siganus rivulatus, Saurida lessepsianus, Pterois miles, Upeneus moluccensis, Charybdis (Archias) longicollis, and Caulerpa cylindracea were the most numerous. The temporal distribution of the records ranges from 1973 to 2022, with 44% of the records in 2020–2021. Lethrinus borbonicus is reported for the first time in the Mediterranean Sea, while Pomatoschistus quagga, Caulerpa cylindracea, Grateloupia turuturu, and Misophria pallida are first records for the Black Sea; Kapraunia schneideri is recorded for the second time in the Mediterranean and for the first time in Israel; Prionospio depauperata and Pseudonereis anomala are reported for the first time from the Sea of Marmara. Many first country records are also included, namely: Amathia verticillata (Montenegro), Ampithoe valida (Italy), Antithamnion amphigeneum (Greece), Clavelina oblonga (Tunisia and Slovenia), Dendostrea cf. folium (Syria), Epinephelus fasciatus (Tunisia), Ganonema farinosum (Montenegro), Macrorhynchia philippina (Tunisia), Marenzelleria neglecta (Romania), Paratapes textilis (Tunisia), and Botrylloides diegensis (Tunisia).Stelios Katsanevakis, Michail Ragkousis, Maria Sini, Markos Digenis and Vasilis Gerovasileiou were supported by the Hellenic Foundation for Research and Innovation (HFRI) under the “First Call for HFRI Research Projects to support Faculty members and Researchers and the procurement of high-cost research equipment grant” (Project ALAS – “ALiens in the Aegean – a Sea under siege” (Katsanevakis et al. 2020b); Project Number: HFRI-FM17-1597). Konstantinos Tsirintanis was co-financed by Greece and the European Union (European Social Fund-ESF) through the Operational Programme “Human Resources Development, Education and Lifelong Learning”, 2014-2020, in the context of the Act “Enhancing Human Resources Research Potential by undertaking a Doctoral Research” Sub-action 2: IKY Scholarship Programme for PhD candidates in the Greek Universities. Maria Zotou was supported by the project “Coastal Environment Observatory and Risk Management in Island Regions AEGIS+” (MIS 5047038), implemented within the Operational Programme “Competitiveness, Entrepreneurship and Innovation” (NSRF 2014-2020), co financed by the Hellenic Government (Ministry of Development and Investments) and the European Union (European Regional Development Fund, Cohesion Fund). Razy Hoffman was supported by Yad-Hanadiv Foundation, through the Israel Society of Ecology and Environmental Sciences and Israel Nature and Parks Authority, an integrated program for establishing biological baselines and monitoring protocols for marine reserves in the Israeli Mediterranean Sea (Grant #10669). Tatiana Begun, Adrian Teaca and Mihaela Muresan were supported by the European Union’s Horizon 2020 BRIDGE-BS project under grant agreement no. 101000240. Fiona Tomas was supported by the project “Invasion of the tropical alga Halimeda incrassata in the Balearic Islands: ecology and invasion dynamics (AAEE119/2017)”, funded by the Vicepresidencia y Consejería de Innovación, Investigación y Turismo del Govern de les Illes Balears, with support from the European Union and FEDER funds, and the project “Una nueva alga invasora en el Mediterráneo: invasibilidad, detección y erradicación del alga tropical Halimeda incrassata (INVHALI)”, funded by the Fundación Biodiversidad, del Ministerio para la Transición Ecológica y el Reto Demográfico. Simonetta Fraschetti, Laura Tamburello, Antonia Chiarore were supported by the project PO FEAMP 2014-2020 - DRD n. 35/2019, “Innovazione, sviluppo e sostenibilità nel settore della pesca e dell'acquacoltura per la Regione Campania” (ISSPA 2.51) and the EU EASME - EMFF (Sustainable Blue Econ-omy) Project AFRIMED (http://afrimed-project.eu/, grant agreement N. 789059). Carlos Jimenez, Louis Hadjioannou, Vasilis Resaikos, Valentina Fossati, Magdalene Papatheodoulou, and Antonis Petrou were supported by MedPan Small Projects, Mava, and LIFE-IP. Louis Hadjioannou, Manos L. Moraitis and Neophytos Agrotis received funding from the European Union’s Horizon 2020 research and innovation program within the framework of the CMMI/MaRITeC-X project under grant agreement No. 857586. Ernesto Azzurro was supported by the project USEIt - Utilizzo di Sinergie operative per la gestione integrata specie aliene Invasive in Italia, funded by the research programme @CNR. Antonietta Rosso and Francesco Sciuto were supported by the University of Catania through “PiaCeRi-Piano Incentivi per la Ricerca di Ateneo 2020–22 linea di intervento 2.” This is the Catania Paleoecological Research Group contribution n. 484. Diego K. Kersting was supported by the Beatriu de Pinós programme funded by the Secretary of Universities and Research (Government of Catalonia) and the Horizon 2020 programme of research and innovation of the European Union under the Marie Sklodowska-Curie grant agreement No 801370. Francesco Tiralongo was supported by the AlienFish project of Ente Fauna Marina Mediterranea (Scientific Organization for Research and Conservation of Marine Biodiversity, 96012 Avola, Italy), a citizen science project for monitoring and studying rare and non-indigenous fish in Italian waters. Adriana Vella, was supported by funds through the BioCon_Innovate Research Excellence Grant from the University of Malta awarded to her. Noel Vella was supported by REACH HIGH Scholars Programme-Post Doctoral Grant for the FINS project. Some of the records provided by Victor Surugiu were obtained during surveys carried out within the framework of the project “Adequate management of invasive species in Romania, in accordance with EU Regulation 1143/2014 on the prevention and management of the introduction and spread of invasive alien species”, SMIS 2014+ 120008, coordinated by the Romanian Ministry of Environment, Water and Forests in partnership with the University of Bucharest (2018–2022). Alan Deidun and Alessio Marrone were supported by the “Spot The Alien” citizen science campaign for the monitoring of the Alien species in the Maltese archipelago and by the Interreg Italia-Malta Harmony project. The authors from the National Institute of Biology (Slovenia) acknowledge the financial support of the Slovenian Research Agency (Research Core Funding No. P1-0237) and of the Ministry of Agriculture, Forestry and Food (project “Survey of the species richness and abundance of alien species in the Slovenian Sea”). Emanuele Mancini and Fabio Collepardo Coccia were supported by the project PO-FEAMP 2014-2020 “BIOBLITZ: research, knowledge and participation for the sustainable management of marine resources (BioBlitz Blu 2020)” coordinated by CURSA for MIPAAF, the Italian Ministry of Agricultural, Food and Forestry Policies, Measure 1.40 - Protection and restoration of biodiversity and marine ecosystems and compensation schemes in the context of sustainable fishing activities. Daniele Grech was supported by the PO-FEAMP 2014-2020 project ECOGESTOCK “Approccio ECOsistemico per la tutela e la GEStione delle risorse biologiche e STOCK ittici nelle acque interne”, the citizen science project Progetto Fucales: chi le ha viste? and the Paralenz Every dive counts sponsor. Jamila Rizgalla was supported by the project Snowball for the monitoring of alien species in Libyan waters له اهتفش له اهتدطصا ؟) have you seen it have you fished it?). Gerasimos Kondylatos and Dimitrios Mavrouleas were supported by the project “EXPLIAS” (MIS (ΟΠΣ): 5049912), design and piloting methods of commercial exploitation of invasive alien species with a view to contributing to their population control, coordinated by the National Technical University of Athens with the collaboration of the Hellenic Centre for Marine Research and the University of the Aegean and co-founded by Greece and the European Union. G. Kondylatos and Savvas Nikolidakis were supported by the project “SAMOS” (ID CODE: 32.2072004/001), a study for a submarine productive park in Marathokampos of Samos. Paraskevi K. Karachle, Aikaterini Dogrammatzi, Giorgos A. Apostolopoulos, Kassiani Konida and Melina Nalmpanti were supported by the project “4ALIEN: Biology and the potential economic exploitation of four alien species in the Hellenic Seas”, funded by NRSF 2017-2020 (MIS (ΟΠΣ): 5049511). Fabio Crocetta and Riccardo Virgili were partially funded by the project PO FEAMP Campania 2014–2020, DRD n. 35 of 15th March 2018, Innovazione, sviluppo e sostenibilità nel settore della pesca e dell’acquacoltura per la regione Campania, Misura 2.51, WP5, Task 5.5 Presenza e distribuzione di specie non indigene del macrozoobenthos e del necton in Campania. Michel Bariche was partially funded by the University Research Board of the American University of Beirut (DDF 103951/2592). Constantinos G. Georgiadis, Dimitra Lida Rammou, Paschalis Papadamakis and Sotiris Orfanidis were supported by the MSFD monitoring program. Sonia Smeraldo was supported by the MPA-Engage project, led by the Institute of Marine Sciences of the Spanish National Research Council and funded by the Interreg MED program. Evgeniia Karpova acknowledge that the publication of this article was in part carried out within the framework of the state assignment of the FRC IBSS “Patterns of Formation and Anthropogenic Transformation of Biodiversity and Bioresources of the Azov– Black Sea Basin and Other Regions of the World Ocean” (No. 121030100028-0). Elena Slynko’s work was carried out within the framework of a State Assignment no. 121051100109-1 of IBIW RAS. Manuela Falautano and Luca Castriota were supported by ISPRA citizen science campaigns for the monitoring of alien species through the dedicated institutional project ([email protected]). María Altamirano was supported by the project RUGULOPTERYX funded by Fundación Biodiversidad-Ministerio para la Transición Ecológica y el reto Demográfico (Spain) and the project UMA20-FEDERJA-006 with support from the European Union and FEDER funds and Junta de Andalucía. Records provided by L. Mangialajo were collected in the framework of projects funded by the Pew Charitable Trust, by the European Commission (AFRIMED, http://afrimed-project.eu/, grant agreement N. 789059) and by the Académie 3 de l’Université Côte d’Azur (projet CONVOST).Peer reviewe

Unpublished Mediterranean and Black Sea records of marine alien, cryptogenic, and neonative species

To enrich spatio-temporal information on the distribution of alien, cryptogenic, and neonative species in the Mediterranean and the Black Sea, a collective effort by 173 marine scientists was made to provide unpublished records and make them open access to the scientific community. Through this effort, we collected and harmonized a dataset of 12,649 records. It includes 247 taxa, of which 217 are Animalia, 25 Plantae and 5 Chromista, from 23 countries surrounding the Mediterranean and the Black Sea. Chordata was the most abundant taxonomic group, followed by Arthropoda, Mollusca, and Annelida. In terms of species records, Siganus luridus, Siganus rivulatus, Saurida lessepsianus, Pterois miles, Upeneus moluccensis, Charybdis (Archias) longicollis, and Caulerpa cylindracea were the most numerous. The temporal distribution of the records ranges from 1973 to 2022, with 44% of the records in 2020–2021. Lethrinus borbonicus is reported for the first time in the Mediterranean Sea, while Pomatoschistus quagga, Caulerpa cylindracea, Grateloupia turuturu, and Misophria pallida are first records for the Black Sea; Kapraunia schneideri is recorded for the second time in the Mediterranean and for the first time in Israel; Prionospio depauperata and Pseudonereis anomala are reported for the first time from the Sea of Marmara. Many first country records are also included, namely: Amathia verticillata (Montenegro), Ampithoe valida (Italy), Antithamnion amphigeneum (Greece), Clavelina oblonga (Tunisia and Slovenia), Dendostrea cf. folium (Syria), Epinephelus fasciatus (Tunisia), Ganonema farinosum (Montenegro), Macrorhynchia philippina (Tunisia), Marenzelleria neglecta (Romania), Paratapes textilis (Tunisia), and Botrylloides diegensis (Tunisia).peer-reviewe

Complex refractive index determination using planar and converging beam transfer functions

Terahertz time domain spectroscopy can help us to determine the complex refractive index of materials. To achieve this a theoretical model of the spectrometer has to be implemented; a usual method for refractive index determination is to fit a theoretically calculated transfer function to the experimental data. Material parameter extraction models based on transfer functions can be of varying complexity based on the requirements for accuracy and also the difficulty of factoring all experimental parameters. Here, we are going to show how algorithms based on transfer functions with different complexity can be setup. It will be described howa transfer function can be used to extract the refractive index of material and the key stages of the analysis, the fitting algorithm, and the need for phase unwrapping. Transfer functions of an increasing complexity will be shown, with and without the etalon term, using planar or converging beam. © Springer-Verlag Berlin Heidelberg 2013. © Springer-Verlag Berlin Heidelberg 2013

Computational simulation of thermal energy storage conainer with phase change materials (PCM)

218 σ.Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Υπολογιστική Μηχανική”Τα συστήματα αποθήκευσης λανθάνουσας θερμότητας αποτελούν σημαντικό και αναπόσπαστο κομμάτι στην εξοικονόμηση ενέργειας. Η παρούσα εργασία αποτελεί υπολογιστική προσομοίωση και ανάλυση ενός συστήματος αποθήκευσης θερμικής ενέργειας με Υλικά Αλλαγής Φάσης (Phase Change Materials). Η εργασία έγινε στα πλαίσια του Διατμηματικού Προγράμματος Μεταπτυχιακών Σπουδών «Υπολογιστική Μηχανική» κατά τη διάρκεια του έτους 2011-2012. Συγκεκριμένα, πρόκειται για έναν κυλινδρικό αγωγό θερμού νερού οικιακής χρήσης, στο εσωτερικό του οποίου έχουν τοποθετηθεί κυλινδρικοί σωλήνες που περιέχουν PCM . Γίνεται προσομοίωση της ροής νερού στον αγωγό και της μεταφοράς θερμότητας από τα PCM στο νερό. Με τη βοήθεια του υπολογιστικού κώδικα ANSYS CFX 13.0 πραγματοποιείται μοντελοποίηση του συστήματος του κυλινδρικού αγωγού, των φυσικών ιδιοτήτων του προβλήματος και των οριακών συνθηκών στον όγκο ελέγχου. Από την ανάλυση του πεδίου ροής και του θερμικού πεδίου που αναπτύσσεται μέσα στη δεξαμενή κατά τη διαδικασία αποφόρτισης του συστήματος, εξετάζεται η ικανότητα αποθήκευσης θερμότητας από τη χρήση ΥΑΦ και εκτιμώνται οι όποιες διαφοροποιήσεις από την αλλαγή κάποιας παραμέτρου. Τα δύο πρώτα κεφάλαια αποτελούν θεωρητικά στοιχεία για τα συστήματα αποθήκευσης θερμικής ενέργειας και για τα ΥΑΦ και τις ιδιότητες τους. Τα επόμενα κεφάλαια αναφέρονται στην υπολογιστική προσομοίωση με το 3ο να δίνει πληροφορίες για το πρόγραμμα Υπολογιστικής Ρευστοδυναμικής ANSYS CFX, το 4ο να παρουσιάζει το μοντέλο που χρησιμοποιήθηκε και το 5ο τα υπολογιστικά αποτελέσματα και τα συμπεράσματά μας. Η υπολογιστική προσομοίωση πραγματοποιήθηκε για να μελετηθεί κυρίως η συμπεριφορά των ΥΑΦ με σε ένα σύστημα αποθήκευσης θερμικής ενέργειας . Τα πρώτα αναλυτικά αποτελέσματα αφορούν το πεδίο ροής εντός της δεξαμενής και δίνεται μια ποιοτική ερμηνεία. Στη συνέχεια δίνονται αποτελέσματα της θερμικής ανάλυσης, από τη μελέτη των ποιοτικών χαρακτηριστικών του συστήματος που έχει προσομοιωθεί με ΥΑΦ σε σύγκριση με άλλα συστήματα και εξάγονται συμπεράσματα για την αποτελεσματική επίδραση του PCM στην αποθήκευση θερμότητας. Ακολουθεί η αξιολόγηση του μοντέλου μέσω της σύγκρισης με τα αντίστοιχα πειραματικά δεδομένα για το συγκεκριμένο σύστημα. Ύστερα έπονται μια σειρά από παραμετρικές αναλύσεις που βοηθούν στην περαιτέρω κατανόηση των ιδιαιτεροτήτων του προβλήματος.The latent heat storage systems are an important and integral part in saving energy. This thesis is a computational simulation and analysis of a thermal energy storage system with Phase Change Materials. This work is part of the PostGraduate Master “Computational Mechanics” during the academic year 2011-2012. Specifically , the work is about a domestic hot water cylindrical tank, within which are mounted cylindrical PVC tubes containing PCM. It is a simulation of the water flow in the tank and the heat transfer from the PCM to water. The modeling of the system , the definition of the physical properties of the problem and the determination of the boundary conditions on the control volumes becomes using the computational software ANSYS CFX 13.0. From analysis of the water flow and the thermal field in the tank during the water system discharge , the heat storage possibilities of including PCM are considered and any variations of changing a physical parameter are estimated. The first two chapters are theoretical points on thermal energy storage systems, phase change materials and their properties. The next chapters refer to the computational simulation. The third gives information about the CFD program ANSYS CFX, the following chapter presents the model which is used for the numerical simulation and the last contains the computational results and our concluding remarks.Βασίλης Χ. Aποστολόπουλο

Simulation of THz generation and propagation from photo-Dember emitters

We demonstrate a simulation of lateral photo-Dember terahertz (THz) emitters in two dimensions using the drift diffusion equation coupled to a finite-difference time-domain model with a far-field algorithm that can take into account the angular spectrum of emission and propagation. We show that the dynamics of the system are more dependent on the currents traveling perpendicular to the semiconductor surface, as opposed to just the lateral currents as previously thought. The 2D simulation is needed in order to correctly represent experiments that measure emission out of lateral photo-Dember emitters.</p