Assessing the Effectiveness of CFD to Solve an Inverse Problem of Thermal Profiles for the ProtoDUNE-SP Neutrino Detector

Computational fluid dynamics (CFD) is a branch of fluid mechanics which is employed to numerically solve complex fluid, heat transfer, and multiphysics problems. Traditionally, CFD techniques are used to solve “forward” problems—using some known information of a system as inputs to a representative model to predict experimental measurements or expected system behavior. The work presented here demonstrates how CFD may be used to solve an “inverse” problem—given limited experimental data and some model, predict (previously unidentified) “input” system (or system model) parameters. The case study for this research uses a validated CFD modeling approach of the liquid argon (LAr) region of the ProtoDUNE Single Phase neutrino detector. Incomplete experimental temperature data (which deviated from the expected, roughly-linear distribution with height for such a natural convection driven flow) are used to inform parametric changes to the base CFD model. Features such as the addition of previously neglected physical geometries and heat sources were parametrically added to the model in the commercial CFD program Star-CCM+, and the resulting temperature distributions were compared to the experimental data. Results of this study suggest that there are numerous possible causes for the abnormal experimental temperature distribution. Model inputs such as increased heat from the cold electronics and the field cage (Faraday cage) and lowering of the LAr height caused a more nonlinear temperature distribution in the sensor region, improving CFD agreement. The addition of previously neglected flow obstructions near the LAr surface do not directly improve the temperature agreement but are significant to the flow patterns and thus should be included in future modeling. Confidence in the inverse problem solution is limited by uncertainties in “known” system information

A Comprehensive Numerical Approach to Coil Placement in Cerebral Aneurysms: Mathematical Modeling and In Silico Occlusion Classification

Endovascular coil embolization is one of the primary treatment techniques for cerebral aneurysms. Although it is a well established and minimally invasive method, it bears the risk of sub-optimal coil placement which can lead to incomplete occlusion of the aneurysm possibly causing recurrence. One of the key features of coils is that they have an imprinted natural shape supporting the fixation within the aneurysm. For the spatial discretization our mathematical coil model is based on the Discrete Elastic Rod model which results in a dimension-reduced 1D system of differential equations. We include bending and twisting responses to account for the coils natural curvature. Collisions between coil segments and the aneurysm-wall are handled by an efficient contact algorithm that relies on an octree based collision detection. The numerical solution of the model is obtained by a symplectic semi-implicit Euler time stepping method. Our model can be easily incorporated into blood flow simulations of embolized aneurysms. In order to differentiate optimal from sub-optimal placements, we employ a suitable in silico Raymond-Roy type occlusion classification and measure the local packing density in the aneurysm at its neck, wall-region and core. We investigate the impact of uncertainties in the coil parameters and embolization procedure. To this end, we vary the position and the angle of insertion of the microcatheter, and approximate the local packing density distributions by evaluating sample statistics

Focus+Context via Snaking Paths

Focus+context visualizations reveal specific structures in high detail while effectively depicting its surroundings, often relying on transitions between the two areas to provide context. We present an approach to generate focus+context visualizations depicting cylindrical structures along snaking paths that enables the structures themselves to become the transitions and focal areas, simultaneously. A method to automatically create a snaking path through space by applying a path finding algorithm is presented. A 3D curve is created based on the 2D snaking path. We describe a process to deform cylindrical structures in segmented volumetric models to match the curve and provide preliminary geometric models as templates for artists to build upon. Structures are discovered using our constrained volumetric sculpting method that enables removal of occluding material while leaving them intact. We find the resulting visualizations effectively mimic a set of motivating illustrations and discuss some limitations of the automatic approach

Space Between Lines: Diagrammatic Architecture and 3D Printing

All forms of communication require a medium to translate abstract thoughts from the mind to an observable and measurable artifact. Whether it is through body movement, vocalization, drawing, making, or multimedia, all ideas rely on some form of medium to leap from the mind and into physical reality. 3D printing is an emerging technology being investigated and developed in many different areas such as medical, aeronautical, as well as in architectural fields. Using 3D printers, digital models can be physically fabricated quickly, giving the maker tactile feedback which can reinform the digital model for further iterations and variations. In this thesis, an extrusion-based 3D printer is utilized as a sketching tool for the mind. Just as a pen and paper allow the architect to explore conceptual and abstract architecture and space through representations, the 3D printer and its software are used as a medium between ideas and its material reification. Six interconnected exercises range from establishing an intuitive workflow with the 3D printer to exploring 3D printed diagrammatic architecture

The tool space

Visions of futuristic desktop computer work spaces have often incorporated large interactive surfaces that either integrate into or replace the prevailing desk setup with displays, keyboard and mouse. Such visions often connote the distinct characteristics of direct touch interaction, e.g. by transforming the desktop into a large touch screen that allows interacting with content using one’s bare hands. However, the role of interactive surfaces for desktop computing may not be restricted to enabling direct interaction. Especially for prolonged interaction times, the separation of visual focus and manual input has proven to be ergonomic and is usually supported by vertical monitors and separate – hence indirect – input devices placed on the horizontal desktop. If we want to maintain this ergonomically matured style of computing with the introduction of interactive desktop displays, the following question arises: How can and should this novel input and output modality affect prevailing interaction techniques. While touch input devices have been used for decades in desktop computing as track pads or graphic tablets, the dynamic rendering of content and increasing physical dimensions of novel interactive surfaces open up new design opportunities for direct, indirect and hybrid touch input techniques. Informed design decisions require a careful consideration of the relationship between input sensing, visual display and applied interaction styles. Previous work in the context of desktop computing has focused on understanding the dual-surface setup as a holistic unit that supports direct touch input and allows the seamless transfer of objects across horizontal and vertical surfaces. In contrast, this thesis assumes separate spaces for input (horizontal input space) and output (vertical display space) and contributes to the understanding of how interactive surfaces can enrich indirect input for complex tasks, such as 3D modeling or audio editing. The contribution of this thesis is threefold: First, we present a set of case studies on user interface design for dual-surface computer workspaces. These case studies cover several application areas such as gaming, music production and analysis or collaborative visual layout and comprise formative evaluations. On the one hand, these case studies highlight the conflict that arises when the direct touch interaction paradigm is applied to dual-surface workspaces. On the other hand, they indicate how the deliberate avoidance of established input devices (i.e. mouse and keyboard) leads to novel design ideas for indirect touch-based input. Second, we introduce our concept of the tool space as an interaction model for dual-surface workspaces, which is derived from a theoretical argument and the previous case studies. The tool space dynamically renders task-specific input areas that enable spatial command activation and increase input bandwidth through leveraging multi-touch and two-handed input. We further present evaluations of two concept implementations in the domains 3D modeling and audio editing which demonstrate the high degrees of control, precision and sense of directness that can be achieved with our tools. Third, we present experimental results that inform the design of the tool space input areas. In particular, we contribute a set of design recommendations regarding the understanding of two-handed indirect multi-touch input and the impact of input area form factors on spatial cognition and navigation performance.Zukunftsvisionen thematisieren zuweilen neuartige, auf großen interaktiven Oberflächen basierende Computerarbeitsplätze, wobei etablierte PC-Komponenten entweder ersetzt oder erweitert werden. Oft schwingt bei derartigen Konzepten die Idee von natürlicher oder direkter Toucheingabe mit, die es beispielsweise erlaubt mit den Fingern direkt auf virtuelle Objekte auf einem großen Touchscreen zuzugreifen. Die Eingabe auf interaktiven Oberflächen muss aber nicht auf direkte Interaktionstechniken beschränkt sein. Gerade bei längerer Benutzung ist aus ergonomischer Sicht eine Trennung von visuellem Fokus und manueller Eingabe von Vorteil, wie es zum Beispiel bei der Verwendung von Monitoren und den gängigen Eingabegeräten der Fall ist. Soll diese Art der Eingabe auch bei Computerarbeitsplätzen unterstützt werden, die auf interaktiven Oberflächen basieren, dann stellt sich folgende Frage: Wie wirken sich die neuen Ein- und Ausgabemodalitäten auf vorherrschende Interaktionstechniken aus? Toucheingabe kommt beim klassischen Desktop-Computing schon lange zur Anwendung: Im Gegensatz zu sogenannten Trackpads oder Grafiktabletts eröffnen neue interaktive Oberflächen durch ihre visuellen Darstellungsmöglichkeiten und ihre Größe neue Möglichkeiten für das Design von direkten, indirekten oder hybriden Eingabetechniken. Fundierte Designentscheidungen erfordern jedoch eine sorgfältige Auseinandersetzung mit Ein- und Ausgabetechnologien sowie adequaten Interaktionsstilen. Verwandte Forschungsarbeiten haben sich auf eine konzeptuelle Vereinheitlichung von Arbeitsbereichen konzentriert, die es beispielsweise erlaubt, digitale Objekte mit dem Finger zwischen horizontalen und vertikalen Arbeitsbereichen zu verschieben. Im Gegensatz dazu geht die vorliegende Arbeit von logisch und räumlich getrennten Bereichen aus: Die horizontale interaktive Oberfläche dient primär zur Eingabe, während die vertikale als Display fungiert. Insbesondere trägt diese Arbeit zu einem Verständnis bei, wie durch eine derartige Auffassung interaktiver Oberflächen komplexe Aufgaben, wie zum Beispiel 3D-Modellierung oder Audiobearbeitung auf neue und gewinnbringende Art und Weise unterstützt werden können. Der wissenschaftliche Beitrag der vorliegenden Arbeit lässt sich in drei Bereiche gliedern: Zunächst werden Fallstudien präsentiert, die anhand konkreter Anwendungen (z.B. Spiele, Musikproduktion, kollaboratives Layout) neuartige Nutzerschnittstellen für Computerarbeitsplätze explorieren und evaluieren, die horizontale und vertikale interaktive Oberflächen miteinander verbinden. Einerseits verdeutlichen diese Fallstudien verschiedene Konflikte, die bei der Anwendung von direkter Toucheingabe an solchen Computerarbeitsplätzen hervorgerufen werden. Andererseits zeigen sie auf, wie der bewusste Verzicht auf etablierte Eingabegeräte zu neuen Toucheingabe-Konzepten führen kann. In einem zweiten Schritt wird das Toolspace-Konzept als Interaktionsmodell für Computerarbeitsplätze vorgestellt, die auf einem Verbund aus horizontaler und vertikaler interaktiver Oberfläche bestehen. Dieses Modell ergibt sich aus den vorangegangenen Fallstudien und wird zusätzlich theoretisch motiviert. Der Toolspace stellt anwendungsspezifische und dynamische Eingabeflächen dar, die durch räumliche Aktivierung und die Unterstützung beidhändiger Multitouch-Eingabe die Eingabebandbreite erhöhen. Diese Idee wird anhand zweier Fallstudien illustriert und evaluiert, die zeigen, dass dadurch ein hohes Maß an Kontrolle und Genauigkeit erreicht sowie ein Gefühl von Direktheit vermittelt wird. Zuletzt werden Studienergebnisse vorgestellt, die Erkenntnisse zum Entwurf von Eingabeflächen im Tool Space liefern, insbesondere zu den Themen beidhändige indirekte Multitouch-Eingabe sowie zum Einfluss von Formfaktoren auf räumliche Kognition und Navigation

Study of curved glass photovoltaic module and module electrical isolation design requirements

The design of a 1.2 by 2.4 m curved glass superstrate and support clip assembly is presented, along with the results of finite element computer analysis and a glass industry survey conducted to assess the technical and economic feasibility of the concept. Installed costs for four curved glass module array configurations are estimated and compared with cost previously reported for comparable flat glass module configurations. Electrical properties of candidate module encapsulation systems are evaluated along with present industry practice for the design and testing of electrical insulation systems. Electric design requirements for module encapsulation systems are also discussed

Modelling CPV

A methodology for the simulation of CPV systems is presented in four distinct sections: input, optics, uncertainty and electrical output. In the input section, existing methods of describing the solar irradiation that is incident at the primary optical element of a CPV system are discussed, the inadequacies of the existing methods are explored and conditions of validity for their use drawn. An improved and spectrally extended model for a variable, spatially resolved solar image is arrived at. The model is used to analyse losses at the primary concentration device stage under varying solar profiles and air masses. A contextual analysis of an example Seattle based CPV system operating with constant solar tracking errors of 0.3-0.4° show a corresponding loss in isolation available to the optical system of 5-20%, respectively. In the optics section, an optical ray trace model is developed specifically for this work. The optical ray trace model is capable of the spectrally resolved ray tracing of all insolation input models discussed above. Plano-convex and Fresnel lenses are designed, investigated and compared using each of the insolation models described in the input section. Common CPV component material samples for the plano-convex and Fresnel lenses are analysed for their spectrally resolved optical properties. The computational expense of high resolution spatial and spectral modelling is addressed by means of a spectrally weighted banding method. The optical properties parameter spectral weighting method can be applied to any arbitrary spectral band. The bands used herein correspond to the active ranges of a typical triple-junction solar cell. Each band shows a different spectral dependency. Banded beam irradiation proportions are shown to change by as much as 10% in absolute terms within the air mass range of 1 to 3. Significant variations in spectrally banded illumination profiles are found with the extended light source insolation model. These banded variations are mostly unaccounted for with the use of approximated insolation models, further compounding the argument for extended light source Sun models in CPV system simulations. In the uncertainty section, the limitations of the manufacturing process are explored. Manufacturing tolerance errors from manufacturer datasheets are presented. These production uncertainties are used in the design of an erroneous plano-convex lens which is then analysed with the optical modelled presented in the optics section and compared to the ideal design specification. A 15% variation in maximum intensity value is found alongside a linear shift in the focal crossover point of approximately 0.2mm, although the optical efficiency of the lens remains the same. Framing manufacture errors are investigated for a square Fresnel lens system resulting in a linear shift of the focal centre of approximately 0.85mm. A process for the calculation of wind loading force on a CPV array is also presented. The process uses real 2 second resolution wind data and highlights the chaotic nature of loading force. A maximum force of 1.4kN was found on an example day for a 3m by 3m by 0.1m cuboid (i.e. CPV array); corresponding to a wind speed of approximately 13m/s, which is well within the typical operating range of a CPV tracking system. In the electrical output section, a spatially resolved solar cell model is identified and used for the investigation of solar cell performance under the inhomogeneous cell illumination profiles produced in the uncertainty section. Significant differences in the maximum power point of the cell IVs are found for the ideal and erroneous system illumination profiles. Approximately, a 15% variation is found in the plano-convex lens example, with a relative difference of 4% attributable to illumination profile distortion, and a 6% variation in the module framing component example. These results further highlight the need for the consideration of production uncertainties in CPV system simulation

Direct modeling techniques in the conceptual design stage in immersive environments for DfA&D

Due to the fast – growing competition of the mass – products markets, companies are looking for new technologies to maximize productivity and minimize time and costs. In the perspective of Computer Aided Process Planning (CAPP), companies want to optimize fixture design and assembly planning for different goals. To meet these demands, the designers' interest in Design for Assembly and Disassembly is growing considerably and is increasingly being integrated into the CAPP. The work described in this thesis aims to exploit immersive technologies to support the design of mating elements and assembly / disassembly, by developing a data exchange flow between the immersive environment and the modeling environment that provides the high – level modeling rules, both for modeling features and for assembly relationships. The main objective of the research is to develop the capability to model and execute simple coupling commands in a virtual environment by using fast direct modeling commands. With this tool the designer can model the coupling elements, position them and modify their layout. Thanks to the physical engine embedded in the scene editor software, it is possible to take into consideration physical laws such as gravity and collision between elements. A library of predefined assembly features has been developed through the use of an external modeling engine and put into communication with the immersive interaction environment. Subsequently, the research involved the study of immersive technologies for workforce development and training of workers. The research on immersive training involved industrial case studies, such as the projection of the disassembly sequence of an industrial product on a head mounted display, and less industrial case studies, such as the manual skills development of carpenters for AEC sectors and the surgeon training in the pre – operative planning in medical field

Warping geometric structures and abelianizing SL(2,R) local systems

The abelianization process of Gaiotto, Hollands, Moore, and Neitzke parameterizes SL(K,C) local systems on a punctured surface by turning them into C^\times local systems, which have a much simpler moduli space. When applied to an SL(2,R) local system describing a hyperbolic structure, abelianization produces an R^\times local system whose holonomies encode the shear parameters of the hyperbolic structure. This dissertation extends abelianization to SL(2,R) local systems on a compact surface, using tools from dynamics to overcome the technical challenges that arise in the compact setting. Thurston's shear parameterization of hyperbolic structures, which has its own technical subtleties on a compact surface, once again emerges as a special case.Mathematic

Software development for the optimization of the influence of wind flows within energy applications and sustainable town planning

Tesi en modalitat de cotutela: Universitat Politècnica de Catalunya i Università degli Studi Gabriele d'AnnuzioThis thesis aims to propose and validate an innovative, fully open-source framework capable of performing multiscale analysis for the assessment of local wind flows within the urban fabric. Each part of the framework is fully editable and license-free. A crucial aspect of the adopted methodology concerns the coupling between the mesoscale-microscale analysis in order to increase the accuracy of the final results. In detail, the procedure is based on the interaction between the mesoscale values and the microscale values obtained considering different wind directions. The core of the work is the design and development of an open-source application that allows to generate 3D numerical models for microscale analysis in an automatic way and providing only some basic information. The main benefit of such a procedure is the drastic reduction of the time required for the creation of numerical models and the facilitation, in general, of microscale simulations. The process of geodata retrieval and the subsequent 3D modeling phase, in fact, are completely automated. The results obtained with the above application are compared with those obtained with a commercial software, widely used in the sector, in order to test its potential and accuracy. Finally, the airflows estimated through the application of the whole proposed framework are used as input for dynamic energy simulations to identify the energy consumption, divided into heating and cooling, of a real building located in an urban context. The framework has been tested assuming a domain located in the city of Pescara (central Italy). However, it is important to emphasize that its application to different urban contexts does not present any constraint related, for example, to the geographical location of the area of interest and that it is, therefore, possible to replicate the analysis in any part of the world.La presente tesis tiene como objetivo proponer y validar un marco de trabajo innovador y totalmente de código abierto (open-source) capaz de realizar análisis multiescala para evaluar los flujos de vientos locales dentro del tejido urbano. Cada etapa del marco es totalmente editable y libre de licencia. Uno de los aspectos cruciales de la metodología adoptada es el acoplamiento entre las simulaciones mesoescala-microescala, las cuales permiten aumentar la precisión de los resultados finales obtenidos. Concretamente, el procedimiento se basa en la interacción entre los valores mesoescala y microescala obtenidos considerando diferentes direcciones del viento. El núcleo de la tesis es el diseño y desarrollo de una aplicación open-source capaz de generar automáticamente modelos 3D para el análisis microescala, proporcionando únicamente ciertos datos básicos. El principal beneficio de este procedimiento es la drástica reducción del tiempo requerido para la creación de modelos numéricos y la facilidad, en general, de las simulaciones microescala. El proceso de recuperación de datos de carácter geográficos (geodata) y la posterior fase de modelado 3D están, de hecho, completamente automatizados. Los resultados obtenidos con la aplicación desarrollada son comparados con los generados a través de un software comercial, el cual es usado ampliamente en el sector, con el objetivo de validar y probar el potencial y precisión de la aplicación. Finalmente, los flujos de aire calculados a través de la aplicación del marco de trabajo propuesto son usados como datos de entrada para la realización de simulaciones energéticas dinámicas, las cuales permiten identificar el consumo de energía, dividido este en los requisitos de calefacción y refrigeración, de un edificio real ubicado dentro de un contexto urbano. El marco de trabajo y la metodología adoptada han sido testeados asumiendo un dominio local en la ciudad de Pescara, ubicada en el centro de Italia. No obstante, es importante destacar que su aplicación a diferentes contextos urbanos no presenta ninguna restricción, como por ejemplo la ubicación geográfica de interés, siendo por tanto posible replicar el análisis en cualquier parte del mundo independientemente de la ubicación del caso de estudio.La presente tesi intende proporre e validare un framework innovativo, completamente open-source, in grado di eseguire analisi multiscala per la valutazione dei flussi del vento locale all'interno del tessuto urbano. Ogni fase del framework è interamente editabile e a licenza grauita. Aspetto cruciale della metodologia adottata riguarda l’accoppiamento tra le analisi mesoscala-microscala al fine di incrementare l’accuratezza dei risultati finali. Nel dettaglio, la procedura si basa sul far dialogare i valori stimati dalla mesoscala con quelli della microscala ottenuti considerando diverse direzioni del vento in ingresso. Il nucleo principale del lavoro è la progettazione e lo sviluppo di un’applicazione in ambiente open-source che permetta di generare modelli numerici 3D per le analisi microscala in maniera automatica e fornendo solo alcune informazioni basiche. Beneficio principale di una procedura così individuata è la drastica riduzione dei tempi necessari per la realizzazione di modelli numerici e l’agevolazione, in generale, delle simulazioni microscala. Il processo di reperimento dei geodati e la successiva fase di modellazione 3D, infatti, sono completamente automatizzate. I risultati ottenuti con la suddetta applicazione sono confrontati con quelli ottenuti con un software commerciale, largamente utilizzato nel settore, al fine di testarne le potenzialità e l’accuratezza. Infine, i flussi di aria stimati mediante l’applicazione dell’intero framework proposto, sono impiegati come input per le simulazioni energetiche dinamiche per identificare il consumo energetico, suddiviso in riscaldamento e raffrescamento, di un edificio reale localizzato in un contesto urbano. Il framework è stato testato assumendo un dominio situato nella città di Pescara (centro Italia). Tuttavia, è importante sottolineare che, la sua applicazione a diversi contesti urbani non presenta alcun vincolo legato, ad esempio, alla posizione geografica dell’area di interesse e che è quindi possibile replicare le analisi in qualsiasi parte del mondo.Postprint (published version