▼ 

The study of the secondary glass workshop of the 4th – early 5th c. AD, which was excavated at Philippi, has been based on two axes, (A) the technology applied to its function and (B) its production. The technological axe refers to:A1. The equipment of the workshop and the methods of glass-working. The glassworks functioned within the frame of the roman glass industry, where an important part of the glass products were made of glass which had been primarily produced by large-scale glass-making factories located in Syro-palestine and Egypt. Raw glass was then transferred, through a well organised sea-trade network, all over the empire, in order to be re-melted and worked by the local secondary glass workshops and to be sold at the local markets. Three successive glass furnaces functioned in the workshop of Philippi, a rectangular and two circular ones. Their form coincides with known examples from the Mediterranean and N. Europe. A large variety of glass-working and vessel-forming debris was also studied and interpreted.A2. The chemical composition and, consequently, the provenance of the glass used as raw material. The analysis of the main composition of the glass (i.e. main elements and certain minor elements) by electronic microscopy combined with X-ray analysis (SEM – EDXA) indicated that the greatest part of the glass used in the workshop was good quality glass of Syro-palestinian provenance. Manganese had been added to the glass batch, in order to diminish its natural blue-green hue and turn it as colorless as possible. Comparative study suggests that similar glass compositions circulated in the Mediterranean and in W. Europe during the 3rd - 4th c. Other glass compositions have also been recognized, which shed light on glass-workers’ choices, aesthetic trends and commercial contacts of the region before, during and after the workshop’s function.B. The axe of production refers to the types of products manufactured by the glass workshop. Like all production sites of its era, the Philippi workshop manufactured vessels using the blowing technique. The main vessels produced were simple bowls or cups of semi-spherical and truncated conical shape, which possibly combined multiple uses, such as drinking vessels and lamps, serving both domestic and religious purposes. Closed tableware or storage / transfer vessels must have been produced in a shorter scale. Window glass also constituted an important part of production. The significance of the glass workshop and the glass as a material in the everyday needs of the roman colony is stressed by the variety of uses of the workshop’s products.Τhe parallel study of chemical composition, working waste and typo-chronology of the vessels also indicates a large-scale re-use / recycling of contemporary or slightly earlier cullet (scrap glass) in combination with the imported primary glass.

Η μελέτη του εργαστηρίου δευτερογενούς παραγωγής γυαλιού (υαλουργείου) του 4ου – πρώιμου 5ου αι. μ.Χ. που ανασκάφηκε στους Φιλίππους διαρθρώθηκε σε δύο άξονες, (Α) εκείνον της τεχνολογίας που…

▼ 

The object of the present work is the application of Spectroscopic and Non Destructive Testing & Evaluation Techniques (NDT&E) for the materials characterization, the decay inspection and the conservation-restoration of historic artefacts. For this purpose the following historic artefacts were studied: i) the Medieval tomb statue of Philippe Dagobert (13th Century AC), Prince of France, with traces of polychromy, exhibited in the Saint Denis Cathedral in Paris, ii) the Byzantine wallpaintings of two Churches (14th Century AC) located in the area of Rethymno in Crete, iii) a group of highly decorated coloured glass objects originated from the Aegean region and dated in a period between the 5th and 4th century BC, iv) copper based objects dated at the Early (2700- 2300 BC) and Late (1500-1050 BC) Bronze Age from Greece. The glass and copper based artefacts belong to the National Archaeological Museum of Athens. The Spectroscopic and Non Destructive Techniques that were used are the following: Environmental Scanning Electron Microscopy with Energy Dispersive X Ray Analysis (ESEM-EDX), Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), micro-Raman Spectroscopy, in-situ VIS-ΝearIR Fiber Optics Diffuse Reflectance Spectroscopy (FODRS), Fiber Optics Microscopy (FOM). The above techniques were selected and applied, either in combination or individually, accordingly to the under investigation artefact. The results obtained from the investigation of the different historic artefacts types, by means of appropriately selected Spectroscopic and Non Destructive methods showed that: VIS-NearIR FODRS can be considered as an appropriate non destructive technique for the identification and reproduction of the pigments saved in polychrome sculpture museum artefacts and historic wallpaintings, where no sampling is allowed, contributing significantly to their conservation–restoration. FOM and ESEM–EDX could be used as appropriate non destructive methods for the characterization and the approach of the manufacturing technique of ancient glass objects from which any sampling is forbidden. VIS-NearIR FODRS could be regarded as an appropriate non destructive tool for the approach of the identification of the bulk alloy composition of ancient copper based objects, from which no sampling is allowed, through the spectral measurement of their surface corrosion products colour, contributing significantly to their conservation-restoration.

Το αντικείμενο της διδακτορικής διατριβής είναι η εφαρμογή των Φασματοσκοπικών και Μη Καταστρεπτικών Μεθόδων στο χαρακτηρισμό, τον έλεγχο της φθοράς και τη συντήρηση- αποκατάσταση ιστορικών έργων. Για το σκοπό αυτό μελετήθηκαν οι ακόλουθες περιπτώσεις ιστορικών έργων: i) το Μεσαιωνικό ταφικό μνημείο, με σωζόμενα ίχνη πολυχρωμίας, του Πρίγκιπα της Γαλλίας Philippe Dagobert (13ος αιώνας μ.Χ.) που εκτίθεται στον Καθεδρικό Ναό του Αγίου Διονυσίου στο Παρίσι, ii) οι Βυζαντινοί τοιχογραφικοί διάκοσμοι (14ος αιώνας μ.Χ.) δύο Ναών από το Ρέθυμνο Κρήτης, iii) διακοσμημένα…

▼ Heterogeneous Objects are engineered with multiple materials to achieve multiple functionalities like high hardness, high toughness and low structural weight. Heterogeneous objects are increasingly used to achieve multiple and often conflicting behaviour within a single object. Developing heterogeneous objects needs computational model for design, analysis and manufacturing. The computational model should map the geometry of the object with the material composition. The most general model is the volume based model that decomposes the geometry exhaustively into simple elements and defines the material distribution over these elements. This approach can model a wide range of objects. However, defining material distribution needs manual intervention to select these elements for material continuity, and to segment or subdivide them for better material approximation. Volume based representation is quite large in size and is cumbersome to edit, query or reuse. Feature based approaches have been proposed to address some of these issues. However, current art can model only limited class of Heterogeneous Objects that includes simple material distribution over complex geometry or complex material distribution over simple geometry. The thesis presents a new method to overcome these limitations. The method, a hybrid of volume based and feature based approaches, allows the user to define the complex material distribution over complex geometries intuitively and represent the same. The complex material distribution is modelled using material reference entities that may be mixed-dimensional, inclusive of non-manifold entities. It uses Medial Axis Transform for automated segmentation of these entities into independent regions, where the material distribution can be intuitively prescribed starting from the entity and terminating at the medial axis. The spatial variation of the material is captured by a parameterized distance field from the material reference entities. It develops new constructive operators to build a complex heterogeneous object model that allows the reuse of the existing heterogeneous object models, automates handling of material continuity, and controls the gradation of the material in the interface of the constituent heterogeneous objects. Constructions using these operators can be geometry driven or material driven i.e. the geometric form controls the material distribution or the material distribution is independent of the geometric form. The proposed representation can be adaptively meshed for generation of mesh in the direction of gradation of the material for finite element analysis and process planning for additive manufacturing. An iso-material contour representation has been proposed for process planning of Heterogeneous Object Models. This avoids the stair case effect by depositing material in the direction of material gradation, and avoids over-deposition or under-deposition due to frequent start and stop of the nozzles. The proposed method has been implemented to show that it can model wide range… Advisors/Committee Members: Gurumoorthy, B (advisor).

▼ Solid/Geometric Modeling has been a crucial technology aiding automation in design and manufacturing, forming the core component of CAD/CAM/CAE tools. Solid modeling provides valid computer representations (solid models) of the geometry of objects and, appropriate algorithms to query and process these representations for individual applications. However, recent advances in design and manufacturing are demanding general models of solids which have more than geometrical information. The application under consideration in this thesis is the design and manufacture of heterogeneous objects. Heterogeneous objects are objects composed of several constituent materials mixed in varying proportions throughout the object. This spatial variation in material composition and its microstructure enables the object to possess different physical properties in different regions, which can be exploited to achieve multiple functionalities. Optimal design techniques have been developed which create such heterogeneous objects. Also, manufacturing technology called layered manufacturing (LM) has evolved which is capable of fabricating them. However, the missing link between the design and fabrication is the solid models and algorithms which can represent and process these heterogeneous designs. In this thesis, several issues related to the development of these new models and algorithms are addressed. The first task that is addressed is the development of new solid modeling schemes (heterogeneous solid modeling) that go beyond geometry to capture the material variation that are present in these heterogeneous objects. These representations are then post-processed for fabrication in LM, one of the tasks being adaptive slicing. The second task is to develop appropriate computer algorithms for adaptive slicing. The issue of data transfer is crucial for LM to be widely adopted by the industry. The third task undertaken is the assessment of existing data formats and transfer methods, and identifying the informational needs during process planning in LM. Finally, the fourth task addressed is the development of a generic modeling framework (object modeling) which extends the idea of heterogeneous solid modeling to include models of several attributes of an object in an integrated fashion. Such models can then be coupled with design, analysis and manufacturing methods to create and fabricate heterogeneous objects efficiently. Advisors/Committee Members: Dutta, Debasish (advisor).

▼ 

Accompagner l’intégration de la fabrication additive dans les grands groupes donneurs d’ordres devient crucial pour les sous-traitants. L’enseignement actuel des procédés et des règles de conception, limité à une vision techno-centrée, ne suffit pas pour projeter ses futures applications dans diverses industries telles que l’aéronautique, l’énergie, le médical, etc... D’un côté, les travaux sur la fabrication additive et les observations de terrain indiquent que les connaissances sur ses procédés, les matériaux et leur mise en œuvre sont régulièrement enrichies. D’un autre côté, les travaux de recherche en créativité montrent qu’il est possible de stimuler la capacité créative des individus pour les guider dans la génération d’idées et de concepts créatifs. Cette thèse explore alors un rapprochement possible entre créativité et fabrication additive, dans la perspective de proposer une méthode de créativité et des outils d’applications spécifiques au paradigme additif. Cette liaison vise à mettre en évidence des moyens de stimuler la créativité, dans le contexte spécifique de la fabrication additive. Cette approche a permis de faire émerger le rôle prépondérant des objets intermédiaires qui articulent les interactions entre plusieurs dimensions de la capacité créative : les motivations, les émotions, l’exploration des connaissances, l’alternance individu/collectif et l’organisation spatiale. Elle a aussi fait émerger le besoin de redéfinir les rôles de ces objets intermédiaires au regard de la fabrication additive. En ce sens, deux dispositifs opérationnels de stimulation, basés sur la manipulation d’objets tangibles, ont été conçus puis testés dans des contextes industriels. Les résultats expérimentaux montrent que l’exploration des connaissances matérialisées par ces dispositifs favorise la génération d’idées créatives qui peuvent ouvrir à de futures applications de la fabrication additive. Finalement, une méthode de Créativité par et pour la fabrication additive est proposée. Elle permet d’enrichir à la fois les pratiques méthodologiques des sciences de la conception et les pratiques opérationnelles sur deux terrains : celui de l’industrie de la fabrication additive et celui de l’innovation.

Emphasizing the integration of Additive Manufacturing (AM) into big industrial companies becomes crucial for subcontractors. Teaching additive processes and design rules is a techno-centric vision. It is not sufficient to project future applications of additive manufacturing in various industries such as aeronautics, energy, medical, etc. On one hand, the state of the art and field observations show that AM knowledge is steadily increasing. On the other hand, the state of the art about creativity shows that individuals creative capacity can be stimulated to guide them to the generation of creative ideas and concepts. This thesis then explores a possible linking between AM and creativity in order to propose a methodology and its application tools to stimulate creativity, in the specific context of additive manufacturing. This…

Advisors/Committee Members: Bouchard, Carole (thesis director), Abed, Stéphane (thesis director), Segonds, Frédéric (thesis director).

▼ Conventional solid modeling systems have focused on developing homogeneous models of physical objects to capture their geometry and topology. These systems have thus far been sufficient since most physical objects found in engineering applications are homogeneous and manufacturing applications require us to deal primarily with their geometry. Two recent advances, structural optimization and layered manufacturing (LM) technologies, have brought to the forefront the need for CAD systems to support the design and fabrication of heterogeneous objects (such as multi-materials which have distinct material regions and functional graded materials (FGMs) which have continuous material composition (or microstructure) variation along with the geometry). This thesis describes the needs and components of such a CAD system. In particular, this thesis focuses on the development of a computational framework that is the missing link between the design and fabrication of heterogeneous objects. As part of this framework, a new representation scheme and a process planning method for LM of heterogeneous objects are developed. Several representation schemes (such as voxel-based, finite element-based, and decomposition-based models) have been proposed for heterogeneous objects. The limitations of these schemes are difficulties in model update and modification, and high storage cost. Based on the detailed assessment of these representation, a new representation, namely constructive representation of heterogeneous objects, is proposed. In particular, this new scheme focuses on the construction of complicated heterogeneous objects, guaranteeing desired material continuities at all the interfaces. In order to create various types of heterogeneous primitives, several methods for specifying material composition functions (such as geometry-independent, geometry-dependent functions, and multiple sets of these functions) are developed. Constructive Material Composition (CMC) and corresponding heterogeneous Boolean Operators (e.g., material union, difference, intersection, and partition) are then proposed to illustrate how material continuities are dealt with. LM methods such as Direct Metal Deposition (DMD), Shape Deposition Manufacturing (SDM), and Three Dimensional Printing (3DP) have capability to fabricate complete 3D heterogeneous objects by selectively depositing various materials on a point-wise fashion under computer control. To generate information for driving these LM machines, a new process planning method which takes into account the processing of material information, is proposed. The detailed tasks of this method are pre-processing (discretization), orientation (build direction selection), and adaptive slicing of heterogeneous objects. In particular, this thesis focuses on the discretization step which converts all material information inside an object into material features like geometric features, thus facilitating the build direction selection, adaptive slicing and tool path generation. Finally, an integrated prototype CAD… Advisors/Committee Members: Dutta, Debasish (advisor).

▼ 

This thesis examines the metalworking of the Late Bronze Age (ca. 1600-1000 BC) in Epirus through the study of bronze tools and bronze weapons, as well as the three small hoards of bronze objects (Stefani in Preveza, Katamachi and Rodotopi in Ioannina). The prehistoric bronze objects of Epirus derive from graves (burial gifts) and hoards (functional products or raw material), from Dodona (probably votive offerings) or consist individual finds without safe archaeological context. Typologically axes (double-edged, shaft-hole or trunnion axes), several smaller categories of bronze tools (chisels, knives, anvils) and weapons (swords-daggers, spearheads) are included.Macroscopic observation (traces of casting, forging, decoration, marking, use-wear) and metallographic examination by optical microscopy (defining structural phases, hot/cold forging, hardness) aim to decode the final stages of the manufacturing procedure. Moreover, the potentials of the scanning electron microscope (SEM) and the analysis with the method of energy dispersive X-ray fluorescence (EDXRF) are utilized to investigate the chemical composition of the objects. The lead isotope analysis by multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) on the possible origin of copper include far enough theoretical problems and are accepted with skepticism.The hard geophysical environment and the corresponding lifestyle shape through time introversion and self-sufficiency of material culture or the economic orientation of Epirus. The quantity of bronze tools and weapons impresses against the volume of local handmade pottery production and consumption. Their typology justifies the location and the prehistoric identity of Epirus between the periphery of the Mycenaean world and the Balkans. Neither copper ores exist in Epirus, nor are any direct-primary indications for the practice of local metalworking activities yet known. However, the typological and quantitative-qualitative characteristics of the manufacturing technology may substantiate common laboratory circles in the closer and wider region of Epirus. It remains for future systematic interdisciplinary research to substantiate with new finds on the availability of local metalworking activity.

Η παρούσα διδακτορική διατριβή εξετάζει τη μεταλλοτεχνία της Ύστερης Εποχής Χαλκού (περίπου 1600-1000 π.Χ.) στην Ήπειρο μέσα από τη μελέτη των χάλκινων εργαλείων και λιγότερο των χάλκινων όπλων, αλλά και των τριών μικρών θησαυρών χάλκινων αντικειμένων (Στεφάνη Πρέβεζας, Καταμάχη και Ροδοτόπι Ιωαννίνων). Τα προϊστορικά χάλκινα αντικείμενα της Ηπείρου προέρχονται από τάφους (κτερίσματα) και θησαυρούς (λειτουργικά προϊόντα ή πρώτη ύλη), από τη Δωδώνη (πιθανά αναθήματα) ή αποτελούν μεμονωμένα ευρήματα χωρίς ασφαλές αρχαιολογικό περιβάλλον. Τυπολογικά περιλαμβάνονται πελέκεις (αμφίστομοι, μονόστομοι ή σταυροπελέκεις) και διάφορες μικρότερες κατηγορίες χάλκινων εργαλείων (σμίλες, μαχαίρια, αμόνια), αλλά και όπλα (ξίφη-εγχειρίδια, αιχμές δοράτων).Μακροσκοπική παρατήρηση (ίχνη κατασκευής, σφυρηλάτησης,…

▼ 

Durch die, vom NÖ Landesmuseum seit 1983 durchgeführten Plangrabungen, kamen in den Katastralgemeinden Asparn/Zaya und Schletz (NÖ) bis zum Jahre 2005 147 Objekte aus Knochen, Zahn und Geweih ans Licht, welche in der vorliegenden Arbeit vorgestellt werden. Besonders in neolithischer Zeit wurden tierische Rohmaterialien wie Knochen, Geweih und Zahn zur Herstellung von Werkzeugen, Alltagsgegenständen und Schmuck genutzt. Die verschiedenen Artefakttypen stellen ein charakteristisches Element der jeweiligen Epoche bzw. Kultur dar, erfuhren jedoch bis dato – im Vergleich zu den keramischen Gütern bzw. dem Steininventar – nur in Einzelfällen nähere Zuwendung im Sinne einer Aufarbeitung bzw. Beschreibung des Materials. Dass diese Quellengattung in der Literatur nicht allzu häufig vorzufinden ist, ist schließlich auch Resultat ihrer, durch die Bodenverhältnisse bedingten, regional sehr unterschiedlichen Erhaltung. Die vorgelegten Knochen-, Zahn- und Geweihobjekte stammen zum Großteil aus linearbandkeramischem Kontext (132 Objekte), es wurden jedoch auch frühbronzezeitliche (13) und völkerwanderungszeitliche (2) Artefakte, welche im Zuge der Erforschung der, durch ein Grabensystem geschützten, linearbandkeramischen Siedlung zu Tage traten, in die Arbeit aufgenommen, beschrieben und typologisiert. Für die Mehrheit, der auf der Fundstelle Asparn-Schletz aufgetretenen Kulturgüter aus Bein liegen entsprechende Parallelen aus dem gesamten Verbreitungsgebiet der jeweiligen Kultur, welches im Falle der Linearbandkeramik (LBK) von der ungarischen Tiefebene und Polen bis ins Pariser Becken reicht, vor. Da die Beinartefakte wegen ihrer raschen Einbettung und der günstigen Bodenbedingungen teilweise sehr gut erhalten geblieben sind, ermöglichen Bearbeitungs- und Gebrauchsspuren Einblicke in die Herstellung bzw. mögliche Nutzung der Objekte.

Systematic excavations at Asparn/Zaya and Schletz (Lower Austria) conducted by the Lower Austrian Department of Prehistory (NÖLM) started in 1983 and ended in summer 2005. A fortified settlement from the end of the Linear Pottery Culture was recovered, with two oval fortification ditches that run parallel to each other, filled with a mixture of late Notenkopf and early Zseliz pottery - whereas the third ditch, which is suggested to be the oldest, is filled with linear ornamented pottery as well as Notenkopf pottery. The total amount of worked bone, antler and tooth artefacts recovered and studied in my thesis, is 147. The majority of the industry can be attributed to the layers and features that contained early Neolithic pottery (132 objects), but because the place was occupied not only in the Linear Pottery Culture, but in early Bronze Age and Migration Period too, some of the bone implements belong to these periods. The thesis includes the identification of the bone tools from the point of view of the animal species, the description and the typologically classification of the objects, which are represented as graphics. Six maps help to localise the origin of the bone…

▼ 

H διατριβή διερευνά προβλήματα αποδοτικής οργάνωσης χωροταξικών δεδομένων, προτείνει συγκεκριμένες δενδρικές δομές για τη διαχείρισή τους και, τέλος, δίνει παραδείγματα χρήσης τους σε ειδικές περιοχές εφαρμογών. Το πρώτο κεφάλαιο ασχολείται με το γεωμετρικό πρόβλημα της εύρεσης των ισo-προσανατολισμένων ορθογωνίων που περικλείουν ένα query αντικείμενο που μπορεί να είναι ένα ισο-προσανατολισμένο ορθογώνιο είτε σημείο ή κάθετο / οριζόντιο ευθύγραμμο τμήμα. Για την επίλυσή του προτείνεται μια πολυεπίπεδη δενδρική δομή που βελτιώνει τις πολυπλοκότητες των προηγούμενων καλύτερων λύσεων. Το δεύτερο κεφάλαιο εξετάζει το πρόβλημα της ανάκτησης σημείων σε πολύγωνα. H προτεινόμενη γεωμετρική δομή είναι επίσης πολυεπίπεδη και αποδοτική όταν το query πολύγωνο έχει συγκεκριμένες ιδιότητες. Το τρίτο κεφάλαιο ασχολείται με την εφαρμογή δενδρικών δομών σε δύο βιομηχανικά προβλήματα. Το πρώτο αφορά στη μείωση της πολυπλοκότητας ανίχνευσης συγκρούσεων κατά την κίνηση ενός ρομποτικού βραχίονα σε μια επίπεδη σκηνή με εμπόδια. Ο αλγόριθμος επίλυσης κάνει χρήση μιας ουράς προτεραιότητας και μιας UNION-FIND δομής ενώ αξιοποιεί γνωστές δομές και αλγόριθμους της Υπολογιστικής Γεωμετρίας όπως υπολογισμός κυρτών καλυμμάτων, έλεγχος polygon inclusion, κλπ. Το δεύτερο πρόβλημα ασχολείται με το σχεδιασμό απαιτήσεων υλικών (MRP) σε ένα βιομηχανικό σύστημα παραγωγής. Για το σκοπό αυτό αναπτύχθηκε ένας MRP επεξεργαστής που χρησιμοποιεί διασυνδεμένες λίστες και εκτελείται στην κύρια μνήμη για να είναι αποδοτικός. Το τελευταίο κεφάλαιο εξετάζει το πρόβλημα του ελέγχου της παραγωγής και συγκεκριμένα της δρομολόγησης εργασιών. Στο πλαίσιο αυτό σχεδιάστηκε και υλοποιήθηκε ένα ευφυές σύστημα δρομολόγησης σε περιβάλλον ροής που συνδυάζει γνωσιακή τεχνολογία και προσομοίωση με on-line έλεγχο προκειμένου να υποστηρίξει το διευθυντή παραγωγής στη λήψη αποφάσεων.

Τhe dissertation examines problems of efficient organization of spatial data, proposes specific tree structures for their management, and finally, gives examples of their use in specific application areas. The first chapter is about the problem of finding the iso-oriented rectangles that enclose a query object which can be an iso-oriented rectangle either a point or a vertical / horizontal line segment. A multilevel tree structure is proposed to solve the problem which improves the complexities of the best previous known solutions. The second chapter examines the problem of point retrieval on polygons. The proposed geometric structure is also multileveled and efficient when the query polygon has specific properties. The third chapter is about the application of tree structures in two manufacturing problems. The first one concerns the reduction in the complexity of collision detection as a robotic arm moves on a planar scene with obstacles. For the solution a priority queue and a UNION-FIND structure are used, whereas known data structures and algorithms of Computational Geometry such as construction of convex hulls, polygon inclusion testing, etc. are applied. The…

Advisors/Committee Members: Τσακαλίδης, Αθανάσιος, Sofotassios, Dimitrios, Τσακαλίδης, Αθανάσιος, Σπυράκης, Παύλος, Γαροφαλάκης, Ιωάννης, Παυλίδης, Γεώργιος, Χατζηλυγερούδης, Ιωάννης, Μακρής, Χρήστος, Σταματίου, Ιωάννης.