30 research outputs found

    IST Austria Thesis

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    Fabrication of curved shells plays an important role in modern design, industry, and science. Among their remarkable properties are, for example, aesthetics of organic shapes, ability to evenly distribute loads, or efficient flow separation. They find applications across vast length scales ranging from sky-scraper architecture to microscopic devices. But, at the same time, the design of curved shells and their manufacturing process pose a variety of challenges. In this thesis, they are addressed from several perspectives. In particular, this thesis presents approaches based on the transformation of initially flat sheets into the target curved surfaces. This involves problems of interactive design of shells with nontrivial mechanical constraints, inverse design of complex structural materials, and data-driven modeling of delicate and time-dependent physical properties. At the same time, two newly-developed self-morphing mechanisms targeting flat-to-curved transformation are presented. In architecture, doubly curved surfaces can be realized as cold bent glass panelizations. Originally flat glass panels are bent into frames and remain stressed. This is a cost-efficient fabrication approach compared to hot bending, when glass panels are shaped plastically. However such constructions are prone to breaking during bending, and it is highly nontrivial to navigate the design space, keeping the panels fabricable and aesthetically pleasing at the same time. We introduce an interactive design system for cold bent glass façades, while previously even offline optimization for such scenarios has not been sufficiently developed. Our method is based on a deep learning approach providing quick and high precision estimation of glass panel shape and stress while handling the shape multimodality. Fabrication of smaller objects of scales below 1 m, can also greatly benefit from shaping originally flat sheets. In this respect, we designed new self-morphing shell mechanisms transforming from an initial flat state to a doubly curved state with high precision and detail. Our so-called CurveUps demonstrate the encodement of the geometric information into the shell. Furthermore, we explored the frontiers of programmable materials and showed how temporal information can additionally be encoded into a flat shell. This allows prescribing deformation sequences for doubly curved surfaces and, thus, facilitates self-collision avoidance enabling complex shapes and functionalities otherwise impossible. Both of these methods include inverse design tools keeping the user in the design loop

    Design of decorative 3D models: from geodesic ornaments to tangible assemblies

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    L'obiettivo di questa tesi Ăš sviluppare strumenti utili per creare opere d'arte decorative digitali in 3D. Uno dei processi decorativi piĂč comunemente usati prevede la creazione di pattern decorativi, al fine di abbellire gli oggetti. Questi pattern possono essere dipinti sull'oggetto di base o realizzati con l'applicazione di piccoli elementi decorativi. Tuttavia, la loro realizzazione nei media digitali non Ăš banale. Da un lato, gli utenti esperti possono eseguire manualmente la pittura delle texture o scolpire ogni decorazione, ma questo processo puĂČ richiedere ore per produrre un singolo pezzo e deve essere ripetuto da zero per ogni modello da decorare. D'altra parte, gli approcci automatici allo stato dell'arte si basano sull'approssimazione di questi processi con texturing basato su esempi o texturing procedurale, o con sistemi di riproiezione 3D. Tuttavia, questi approcci possono introdurre importanti limiti nei modelli utilizzabili e nella qualitĂ  dei risultati. Il nostro lavoro sfrutta invece i recenti progressi e miglioramenti delle prestazioni nel campo dell'elaborazione geometrica per creare modelli decorativi direttamente sulle superfici. Presentiamo una pipeline per i pattern 2D e una per quelli 3D, e dimostriamo come ognuna di esse possa ricreare una vasta gamma di risultati con minime modifiche dei parametri. Inoltre, studiamo la possibilitĂ  di creare modelli decorativi tangibili. I pattern 3D generati possono essere stampati in 3D e applicati a oggetti realmente esistenti precedentemente scansionati. Discutiamo anche la creazione di modelli con mattoncini da costruzione, e la possibilitĂ  di mescolare mattoncini standard e mattoncini custom stampati in 3D. CiĂČ consente una rappresentazione precisa indipendentemente da quanto la voxelizzazione sia approssimativa. I principali contributi di questa tesi sono l'implementazione di due diverse pipeline decorative, un approccio euristico alla costruzione con mattoncini e un dataset per testare quest'ultimo.The aim of this thesis is to develop effective tools to create digital decorative 3D artworks. Real-world art often involves the use of decorative patterns to enrich objects. These patterns can be painted on the base or might be realized with the application of small decorative elements. However, their creation in digital media is not trivial. On the one hand, users can manually perform texture paint or sculpt each decoration, in a process that can take hours to produce a single piece and needs to be repeated from the ground up for every model that needs to be decorated. On the other hand, automatic approaches in state of the art rely on approximating these processes with procedural or by-example texturing or with 3D reprojection. However, these approaches can introduce significant limitations in the models that can be used and in the quality of the results. Instead, our work exploits the recent advances and performance improvements in the geometry processing field to create decorative patterns directly on surfaces. We present a pipeline for 2D and one for 3D patterns and demonstrate how each of them can recreate a variety of results with minimal tweaking of the parameters. Furthermore, we investigate the possibility of creating decorative tangible models. The 3D patterns we generate can be 3D printed and applied to previously scanned real-world objects. We also discuss the creation of models with standard building bricks and the possibility of mixing standard and custom 3D-printed bricks. This allows for a precise representation regardless of the coarseness of the voxelization. The main contributions of this thesis are the implementation of two different decorative pipelines, a heuristic approach to brick construction, and a dataset to test the latter

    Let the agents do the talking: On the influence of vocal tract anatomy no speech during ontogeny

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    Intraoperative, Quantitative, and Non-Contact Blood Volume Flow Measurement via Indocyanine Green Fluorescence Angiography

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    In vielen FĂ€llen unterziehen sich Patienten einer Revaskularisationsoperation wenn sie an einer zerebrovaskulĂ€ren Erkrankung leiden, die eine Hypoperfusion des Gehirns verursacht. Dieser chirurgische Eingriff wird hĂ€ufig als offene Operation durchgefĂŒhrt und hat das Ziel, die GefĂ€ĂŸfunktion, insbesondere den Blutfluss, wiederherzustellen. Hierzu wird eine Anastomose (Verbindung von Arterien) angelegt, um den Fluss zu einem hypoperfundierten Gehirnareal zu erhöhen. In ungefĂ€hr 10% der Eingriffe treten nach der Operation Komplikationen auf, die zum Teil auf eine unzureichende Durchflusssteigerung zurĂŒckgefĂŒhrt werden. Daher sollte der Blutfluss intraoperativ ĂŒberprĂŒft werden, um die QualitĂ€t des Eingriffs im Operationssaal zu beurteilen und schnell eingreifen zu können. Damit könnte ein negativer Ausgang fĂŒr den Patienten verhindert werden. Der derzeitige Stand der Technik in der intraoperativen und quantitativen Blutflussmessung ist die Nutzung der Ultraschall-Transitzeit-Durchflusssonde. Sie gibt einen quantitativen Flusswert an, muss jedoch das GefĂ€ĂŸ umschließen. Dies ist einerseits umstĂ€ndlich fĂŒr den Chirurgen und andererseits birgt es das Risiko von Kontaminationen, GefĂ€ĂŸquetschungen und der GefĂ€ĂŸruptur. Eine alternative Methode ist die IndocyaningrĂŒn (ICG) Fluoreszenzangiographie (FA), welche eine kamerabasierte Methode ist. Sie ist der Stand der Technik in der hochauflösenden anatomischen Visualisierung des Situs und kann zusĂ€tzlich dem Chirurgen eine qualitative funktionelle Darstellung der GefĂ€ĂŸe im Sichtfeld liefern. Der Stand der Wissenschaft zur Quantifizierung des Blutflusses mittels ICG-FA konnten bisher keine verlĂ€sslichen Fluss- werte liefern. Die vorliegende Arbeit analysiert und verbessert die Eignung von ICG FA zu Bereitstellung von verlĂ€sslichen und quantitativen Blutflusswerten, indem 1. geklĂ€rt wird, wie akkurat die Messung durchgefĂŒhrt werden kann. 2. Methoden zur Verbesserung der Genauigkeit entwickelt werden. 3. die Existenz eines systematischen Fehlers abgeleitet wird. 4. eine Methode zur Kompensation des systematischen Fehlers entwickelt wird. 5. ein Algorithmus zur Verarbeitung der eingehenden Videodaten fĂŒr eine Ausgabe eines Durchflusswertes bereitgestellt wird. 6. die Validierung der vorgeschlagenen Methoden und des Arbeitsablaufs in einer ex vivo und in vivo Studie durchgefĂŒhrt wird. Die in dieser Arbeit vorgeschlagene Messung basiert auf dem systemic mean transit time theorem fĂŒr Systeme mit einem Eingang und einem Ausgang. Um den Fluss zu berechnen mĂŒssen die Transitzeit eines ICG-Bolus fĂŒr eine zu bestimmenden Strecke und die QuerschnittsflĂ€che des GefĂ€ĂŸes ermittelt werden. Es wurden Methoden entwickelt, um den Blutvolumenstrom zu messen und um Fehlerquellen bei dieser Messung der einzelnen Parameter zu identifizieren, quantifizieren und reduzieren. Die statistischen Fehler bei der Messung der Transitstrecke und der Transitzeit des ICG- Bolus sowie der QuerschnittsflĂ€che des GefĂ€ĂŸes werden in der Forschung oft vernachlĂ€ssigt. In dieser Arbeit wurden die Fehler mit Hilfe von in silico Modellen quantifiziert. Es zeigte sich, dass der Fehler zu groß fĂŒr eine zuverlĂ€ssige Blutflussmessung ist und daher Methoden zu seiner Reduzierung benötigt werden. Um den Fehler bei der LĂ€ngenmessung deutlich zu reduzieren, wurde eine Methode vorgestellt, welche die diskrete Mittellinie wieder in eine kontinuierliche ĂŒberfĂŒhrt. Dabei wird der Fehler in der LĂ€ngenmessung signifikant reduziert und der Fehler von der rĂ€umlichen Orientierung der Struktur entkoppelt. In Ă€hnlicher Weise wurde eine Methode vorgestellt, welche die gemessenen diskreten IndikatorverdĂŒnnungskurven (IDCs) ebenso in kontinuierliche ĂŒberfĂŒhrt, um den Fehler in der Laufzeitmessung des ICG-Bolus zu reduzieren. Der propagierte statistische Fehler der Blutflussmessung wurde auf einen akzeptablen und praktikablen Wert von 20 % bis 30 % reduziert. Die PrĂ€senz eines systematischen Fehlers bei der optischen Messung des Blutflusses wurde identifiziert und aus der Definition des Volumenflusses theoretisch abgeleitet. Folgend wird eine Methode zur Kompensation des Fehlers vorgestellt. Im ersten Schritt wird eine Fluid-Strömungssimulation genutzt, um die rĂ€umlich-zeitliche Konzentration des ICG in einem BlutgefĂ€ĂŸ zu berechnen. Anschließend wird die Konzentration an ein neu entwickeltes Fluoreszenz-Monte-Carlo-Multizylinder (FMCMC) Modell ĂŒbergeben, das die Ausbreitung von Photonen in einem GefĂ€ĂŸ simuliert. Dabei wird der Ort der Fluoreszenzereignisse der emittierten Photonen ermittelt und der systematische Fehler bestimmt. Dies ermöglicht die Kompensation des systematischen Fehlers. Es zeigte sich, dass dieser Fehler unabhĂ€ngig von dem Volumenfluss ist, solange die Strömung laminar ist, aber abhĂ€ngig vom Durchmesser des GefĂ€ĂŸes und dem Zeitpunkt der Messung. Die AbhĂ€ngigkeit vom Durchmesser ist reduziert bei Messungen zu einem frĂŒheren Zeitpunkt. Daher ist es vorteilhaft, die erste Ankunft des ICG-Bolus zur Bestimmung der Transitzeit zu verwenden, um den Einfluss des Durchmessers auf den Fehler zu verringern und somit die Messung robuster durchzufĂŒhren. Um die Genauigkeit der Messung in einem Experiment zu beweisen, wurde ein ex vivo Experiment unter Verwendung von Schweineblut und Kaninchen Aorten konzipiert und durchgefĂŒhrt. Es zeigte sich, dass der durch den vorgeschlagenen Algorithmus ermittelte Fluss mit der Referenzmessung (einem industriellem Durchflussmesser) ĂŒbereinstimmt. Die statistische Streuung der gemessenen Flussdaten durch den Algorithmus stimmte mit der zuvor ermittelten statistischen Fehlerspanne ĂŒberein, was den in silico Ansatz validiert. Es wurde eine retrospektive in vivo Studie an Menschen durchgefĂŒhrt, die sich einer extrakraniellen-zu-intrakraniellen (EC-IC) Bypass Operation unterzogen hatten. Die Analyse der FA-Daten ergab eine gute Übereinstimmung mit der klinischen Referenzmethode, jedoch mit dem großen Vorteil, dass kein Kontakt zum Gewebe erforderlich war. ZusĂ€tzlich wurde gezeigt, dass simultan Flusswerte fĂŒr mehrere GefĂ€ĂŸe im Sichtfeld der Kamera gemessen werden können. Die vorgestellten Ergebnisse sind ein Proof of Concept fĂŒr die Eignung der vorgestellten intraoperativen, quantitativen und optischen Messung des Blutvolumenstroms mittels ICG FA. Diese Arbeit ebnet den Weg fĂŒr den klinischen Einsatz dieser Methode in ErgĂ€nzung zum aktuellen klinischen Stand der Technik. Sie könnte zukĂŒnftig dem Chirurgen eine neuartige Messung des Blutvolumenstroms zur VerfĂŒgung stellen und dabei potentiell das Risiko einer Komplikation reduzieren und damit das Wohl der Patienten verbessern

    Advances on Mechanics, Design Engineering and Manufacturing III

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    This open access book gathers contributions presented at the International Joint Conference on Mechanics, Design Engineering and Advanced Manufacturing (JCM 2020), held as a web conference on June 2–4, 2020. It reports on cutting-edge topics in product design and manufacturing, such as industrial methods for integrated product and process design; innovative design; and computer-aided design. Further topics covered include virtual simulation and reverse engineering; additive manufacturing; product manufacturing; engineering methods in medicine and education; representation techniques; and nautical, aeronautics and aerospace design and modeling. The book is organized into four main parts, reflecting the focus and primary themes of the conference. The contributions presented here not only provide researchers, engineers and experts in a range of industrial engineering subfields with extensive information to support their daily work; they are also intended to stimulate new research directions, advanced applications of the methods discussed and future interdisciplinary collaborations

    The application of three-dimensional mass-spring structures in the real-time simulation of sheet materials for computer generated imagery

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    Despite the resources devoted to computer graphics technology over the last 40 years, there is still a need to increase the realism with which flexible materials are simulated. However, to date reported methods are restricted in their application by their use of two-dimensional structures and implicit integration methods that lend themselves to modelling cloth-like sheets but not stiffer, thicker materials in which bending moments play a significant role. This thesis presents a real-time, computationally efficient environment for simulations of sheet materials. The approach described differs from other techniques principally through its novel use of multilayer sheet structures. In addition to more accurately modelling bending moment effects, it also allows the effects of increased temperature within the environment to be simulated. Limitations of this approach include the increased difficulties of calibrating a realistic and stable simulation compared to implicit based methods. A series of experiments are conducted to establish the effectiveness of the technique, evaluating the suitability of different integration methods, sheet structures, and simulation parameters, before conducting a Human Computer Interaction (HCI) based evaluation to establish the effectiveness with which the technique can produce credible simulations. These results are also compared against a system that utilises an established method for sheet simulation and a hybrid solution that combines the use of 3D (i.e. multilayer) lattice structures with the recognised sheet simulation approach. The results suggest that the use of a three-dimensional structure does provide a level of enhanced realism when simulating stiff laminar materials although the best overall results were achieved through the use of the hybrid model

    Designing italics: Approaches to the design of contemporary secondary text typefaces

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    This thesis investigates the design process of contemporary, Latin-script, secondary italic text typefaces. It examines designers’ approaches, the technical and cultural factors that influence their design decisions, and the techniques they employ. It reviews the historical italic design process, and explores how it informs current designers’ approach to the design of italics. This research sheds new light on a poorly-documented area of typeface design. It also demonstrates a method of design research that compares historical and contemporary practice and produces a framework for description and discussion. Examination of the design process begins with an analysis of the varied roles and identities of italic in Latin-script text typography—as a language feature, typographic element, historical marker, design object, and business product—and how these identities have influenced design. Historical practice is documented and analysed based on a wide range of sources including designer accounts, reviews, journal articles, publications, and type specimens. Contemporary practice is explored though interviews with a broad sample of currently-active designers regarding their approaches, processes,\ud and techniques. Responses are analysed according to stages in the type design process—initiating,experimenting, forming, harmonizing, and adapting—with additional sections on evaluating and learning. These present a comprehensive view of the process and how it relates to historical practice. This thesis then proposes a decision-based framework for description and discussion of the contemporary italic design process, including a fresh look at historical inspiration. It presents a method of approaching and analysing the design process and introduces two new concepts for describing designer decision-making: balanced differentiation and italic tension. It gives examples of how the framework might be applied in various contexts and explores how it might be extended to be useful in the analysis of other secondary styles and to scripts other than Latin

    Interactions gestuelles multi-point et gĂ©omĂ©trie dĂ©formable pour l’édition 3D sur Ă©cran tactile

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    Despite the advances made in the fields of existing objects capture and of procedural generation, creation of content for virtual worlds can not be perform without human interaction. This thesis suggests to exploit new touch devices ("multi-touch" screens) to obtain an easy, intuitive 2D interaction in order to navigate inside a virtual environment, to manipulate, position and deform 3D objects.First, we study the possibilities and limitations of the hand and finger gestures while interacting on a touch screen in order to discover which gestures are the most adapted to edit 3D scene and environment. In particular, we evaluate the effective number of degrees of freedom of the human hand when constrained on a planar surface. Meanwhile, we develop a new gesture analysis method using phases to identify key motion of the hand and fingers in real time. These results, combined to several specific user-studies, lead to a gestural design pattern which handle not only navigation (camera positioning), but also object positioning, rotation and global scaling. Then, this pattern is extended to complex deformation (such as adding and deleting material, bending or twisting part of objects, using local control). Using these results, we are able to propose and evaluate a 3D world editing interface that handle a naturaltouch interaction, in which mode selection (i.e. navigation, object positioning or object deformation) and task selections is automatically processed by the system, relying on the gesture and the interaction context (without any menu or button). Finally, we extend this interface to integrate more complex deformations, adapting the garment transfer from a character to any other in order to process interactive deformation of the garment while the wearing character is deformed.MalgrĂ© les progrĂšs en capture d’objets rĂ©els et en gĂ©nĂ©ration procĂ©durale, la crĂ©ation de contenus pour les mondes virtuels ne peut se faire sans interaction humaine. Cette thĂšse propose d’exploiter les nouvelles technologies tactiles (Ă©crans "multi-touch") pour offrir une interaction 2D simple et intuitive afin de naviguer dans un environnement virtuel, et d’y manipuler, positionner et dĂ©former des objets 3D.En premier lieu, nous Ă©tudions les possibilitĂ© et les limitations gestuelles de la main et des doigts lors d’une interaction sur Ă©cran tactile afin de dĂ©couvrir quels gestes semblent les plus adaptĂ©s Ă  l’édition des environnements et des objets 3D. En particulier, nous Ă©valuons le nombre de degrĂ© de libertĂ© efficaces d’une main humaine lorsque son geste est contraint Ă  une surface plane. Nous proposons Ă©galement une nouvelle mĂ©thode d’analyse gestuelle par phases permettant d’identifier en temps rĂ©el les mouvements clĂ©s de la main et des doigts. Ces rĂ©sultats, combinĂ©s Ă  plusieurs Ă©tudes utilisateur spĂ©cifiques, dĂ©bouchent sur l’identification d’un patron pour les interactions gestuelles de base incluant non seulement navigation (placement de camĂ©ra), mais aussi placement, rotation et mise Ă  l’échelle des objets. Ce patron est Ă©tendudans un second temps aux dĂ©formations complexes (ajout et suppression de matiĂšre ainsi que courbure ou torsion des objets, avec contrĂŽle de la localitĂ©). Tout ceci nous permet de proposer et d’évaluer une interface d’édition des mondes 3D permettant une interaction tactile naturelle, pour laquelle le choix du mode (navigation, positionnement ou dĂ©formation) et des tĂąches correspondantes est automatiquement gĂ©rĂ© par le systĂšme en fonction du geste et de son contexte (sans menu ni boutons). Enfin, nous Ă©tendons cette interface pour y intĂ©grer des dĂ©formations plus complexe Ă  travers le transfert de vĂȘtements d’un personnage Ă  un autre, qui est Ă©tendu pour permettre la dĂ©formation interactive du vĂȘtement lorsque le personnage qui le porte est dĂ©formĂ© par interaction tactile

    Advances on Mechanics, Design Engineering and Manufacturing III

    Get PDF
    This open access book gathers contributions presented at the International Joint Conference on Mechanics, Design Engineering and Advanced Manufacturing (JCM 2020), held as a web conference on June 2–4, 2020. It reports on cutting-edge topics in product design and manufacturing, such as industrial methods for integrated product and process design; innovative design; and computer-aided design. Further topics covered include virtual simulation and reverse engineering; additive manufacturing; product manufacturing; engineering methods in medicine and education; representation techniques; and nautical, aeronautics and aerospace design and modeling. The book is organized into four main parts, reflecting the focus and primary themes of the conference. The contributions presented here not only provide researchers, engineers and experts in a range of industrial engineering subfields with extensive information to support their daily work; they are also intended to stimulate new research directions, advanced applications of the methods discussed and future interdisciplinary collaborations

    Energetic ion dynamics and confinement in 3D saturated MHD configurations

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    In the following theoretical and numerically oriented work, a number of findings have been assembled. The newly devised VENUS-LEVIS code, designed to accurately solve the motion of energetic particles in the presence of 3D magnetic fields, relies on a non-canonical general coordinate Lagrangian formulation of the guiding-centre and full-orbit equations of motion. VENUS-LEVIS can switch between guiding-centre and full-orbit equations with minimal discrepancy at first order in Larmor radius by verifying the perpendicular variation of magnetic vector field, not only including gradients and curvature terms but also parallel currents and the shearing of field-lines. By virtue of a Fourier representation of the fields in poloidal and toroidal coordinates and a cubic spline in the radial variable, the order of the Runge-Kutta integrating scheme is preserved and convergence of Hamiltonian properties is obtained. This interpolation scheme is crucial to compute orbits over slowing-down times, as well as to mitigate the singularity of the magnetic axis in toroidal flux coordinate systems. Three-dimensional saturated MHD states are associated with many tokamak phenomena including snakes and LLMs in spherical or more conventional tokamaks, and are inherent to stellarator devices. The VMEC equilibrium code conveniently reproduces such 3D magnetic configurations. Slowing-down simulations of energetic ions from NBI predict off-axis deposition of particles during LLM MHD activity in hybrid-like plasmas of the MAST. Co-passing particles helically align in the opposite side of the plasma deformation, whereas counter-passing and trapped particles are less affected by the presence of a helical core. Qualitative agreement is found against experimental measurements of the neutron emission. Two opposing approaches to include RMPs in fast ion simulations are compared, one where the vacuum field caused by the RMP current coils is added to the axisymmetric MHD equilibrium, the other where the MHD equilibrium includes the plasma response within the 3D deformation of its flux-surfaces. The first model admits large regions of stochastic field-lines that penetrate the plasma without alteration. The second assumes nested flux-surfaces with a single magnetic axis, embedding the RMPs in a 3D saturated ideal MHD state but excluding stochastic field-lines within the last closed flux-surface. Simulations of fast ion populations from NBI are applied to MAST n=3 RMP coil configuration with 4 different activation patterns. At low beam energies, particle losses are dominated by parallel transport due to the stochasticity of the field-lines, whereas at higher energies, losses are accredited to the 3D structure of the perturbed plasma as well as drift resonances
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