Published Article / Over the past few years, methods of layered manufacturing (LM) have advanced substantially to the point where they now provide vital strategic benefits to various organisations. One area of application where LM technologies have begun to reach a critical mass is in the development and production of high-performance tooling in different forming processes. With these tooling capabilities now available, the next challenge becomes the development of optimal process chains to minimise lead times and production costs, while still ensuring high quality of castings. The relevant issues that influence where a break-even point will be between different process chains and thereby also the point of selection between such optimal process chains according to different situations include among others: <ul> <li> the size of production runs, </li> <li> part size and complexity, and</li> <li> the cast materials involved.</li> </ul> <br>This paper reflects some of the experiences gained from an investigation towards developing a set of generic rules (guidelines) for the design of optimal process chains for sand casting prototypes of automotive components using LM methods, and more specifically the 3D Printing process.

The art of reconstructing a real-world scene digitally has been on the mind of researchers for decades. Recently, it has attracted more and more attention from companies seeing a chance to bring this kind of technology to the market. Digital reconstruction of buildings in particular is a niche that has both potential and room for improvement. With this background, this thesis will present the design and evaluation of a pipeline made to find and correct approximately flat surfaces in architectural scenes. The scenes are 3D-reconstructed triangle meshes based on RGB images. The thesis will also comprise an evaluation of a few different components available for doing this, leading to a choice of best components. The goal is to improve the visual quality of the reconstruction. The final pipeline is designed with two blocks - one to detect initial plane seeds and one to refine the detected planes. The first block makes use of a multi-label energy formulation on the graph that describes the reconstructed surface. Penalties are assigned to each vertex and each edge of the graph based on the vertex labels, effectively describing a Markov Random Field. The energy is minimized with the help of the alpha-expansion algorithm. The second block uses heuristics for growing the detected plane seeds, merging similar planes together and extracting deviating details. Results on several scenes are presented, showing that the visual quality has been improved while maintaining accuracy compared with ground truth data. / Konsten att digitalt rekonstruera en verklig miljö har länge varit intressant för forskare. Nyligen har området även tilldragit sig mer och mer uppmärksamhet från företag som ser en möjlighet att föra den här typen av teknik till produkter på marknaden. I synnerhet är digital rekonstruktion av byggnader en nisch som har både stor potential och möjlighet till förbättring. Med denna bakgrund så presenterar detta examensarbete designen för och utvärderingen av en pipeline som skapats för att detektera och rätta till approximativt platta regioner i arkitektoniska miljöer. Miljöerna är 3D-rekonstruerade triangelmeshar skapade från RGB-bilder. Examensarbetet omfattar även utvärdering av olika komponenter för att uppnå detta, som avslutas med att de mest lämpliga komponenterna presenteras. Målet i korthet är att förbättra den visuella kvaliteten av en rekonstruerad modell. Den slutgiltiga pipelinen består av två övergripande block - ett för att detektera initiala plan och ett för att förbättra de funna planen. Det första blocket använder en multi-label energiformulering på grafen som beskriver den rekonstruerade ytan. Straffvärden tilldelas varje vertex och varje båge i grafen baserade på varje vertex label. På så sätt beskriver grafen ett Markov Random Field. Energin är sedan minimerad med alpha-expansion-algoritmen. Det andra blocket använder heuristiker för att låta planen växa, slå ihop närliggande plan och för att extrahera avvikande detaljer. Resultat på flera miljöer presenteras också för att påvisa att den visuella kvaliteten har förbättrats utan att rekonstruktionens noggrannhet har försämrats jämfört med ground truth-data.

Poster exhibited at GPSC Student Showcase, February 24th, 2016, University of Arizona. Recipient of the 2016 Katheryne B. Willock Library Research Award. / The nervous system is composed of two types of cells: neurons and glia. In neuronal circuits, neurons communicate through synapses and glia play a crucial modulatory role. To modulate chemical reuptake, glia send processes close to synapses and many glia directly appose or ensheathe a synapse. This structural motif is one of the elements often included in describing a vertebrate tripartite synapse, which includes a bidirectional functional neuron-glia relationship. The exact nature of this neuron-glia communication is not well understood. In the invertebrate fruit fly, we have also found that particular neurons and glia also have a bidirectional functional relationship. This allows us to ask new questions about glial morphology. Throughout multiple images, I identified particular neuronal synapses and surrounding glia. After creating a 3D reconstruction, I measured the distance between a particular neuronal synapse and its closest glial process. Interestingly, the neuronal synapses were not directly apposed or ensheathed by glia, and the distance to the closest glial process varied one-hundred-fold. With variable distance, functional communication is consistently present. These findings provide important insight into invertebrate neuron-glia communication, and offer new avenues to investigate the structural neuron-glia relationships that are required for reciprocal signaling between the two cell classes.

L'étude de la stabilité aérodynamique des structures est un domaine très complexe et nécessite généralement des essais à échelle réduite en soufflerie. Ces essais doivent permettre de reproduire le comportement de la structure soumise à des instabilités aérodynamiques telles que le détachement tourbillonnaire et le flottement. Les essais sectionnels permettent de reproduire de manière fiable le comportement d'une section représentative d'une structure. Ces essais sont généralement économiques et peuvent être réalisés dans un court laps de temps, c'est pourquoi ils constituent généralement la première étape d'une série d'essais sur une structure. Historiquement, ils permettent de reproduire le comportement d'une section selon, au maximum, deux degrés de liberté (DDL). La rotation autour de l'axe longitudinal de la structure et la translation perpendiculaire à l'écoulement sont généralement modélisées alors que la translation parallèle à l'écoulement est négligée. Toutefois, il est bien connu que certains phénomènes aérodynamiques, tels que le galop, impliquent des déplacements selon les deux translations. Il est aussi fréquent que le mode de torsion d'une structure soit couplé avec un déplacement transversal ; c'est souvent le cas pour un pont élancé par exemple. Il serait donc intéressant d'étudier l'effet de l'ajout d'un troisième DDL sur la stabilité aérodynamique d'une structure. Le présent travail décrit la conception et la validation d'un montage pour essais sectionnels en soufflerie qui permet le mouvement du modèle selon trois DDL. Plusieurs améliorations, telles que l'ajout d'amortissement magnétique découplé pour chaque DDL et l'utilisation de vérins actifs permettant l'introduction d'un mouvement forcé, ont aussi été apportées au montage original à deux DDL. Les résultats de la validation montrent que l'ajout du DDL horizontal, sous certaines conditions, a une influence sur le comportement de la section, notamment lors de l'apparition du flottement.

The majority of cancer research projects mainly focus on the epithelial cancer cell, while the role of the tumour stroma has been largely neglected. Conventional 2D techniques, such as well plates and other kinds of tissue culture plastic, and animal models are mainly used to broaden our understanding of how tumours arise, develop, and induce metastasis. However, there is accumulating evidence suggesting a tremendous impact of the non‐cancerous tumour stroma on carcinogenesis, while other publications illustrate the great importance of advanced 3D in vitro models for cancer research. The overall goal of this work was to investigate how cancer associated fibroblasts (CAFs; the most abundant component in the tumour stroma) and normal prostate fibroblasts (NPFs), isolated from patients diagnosed with aggressive forms of prostate cancer, contribute to angiogenesis, an important hallmark of cancer progression. For this purpose, a 3D in vitro angiogenesis co‐culture model was established. At first, two (semi‐) synthetic hydrogel platforms, gelatine methacrylate (GelMA) and star‐shaped (star)PEG‐heparin hydrogels were characterised and their physicochemical properties were compared with each other. Interestingly, GelMA gels shrank while starPEG‐heparin gels swelled in cell culture medium over the course of 24 hours. The cell concentration, in addition to the stiffness, was critical for the formation of endothelial networks, and the knowledge of swelling behaviour enabled the adjustment of initial cell density to ensure the density between both gel types was comparable. Moreover, preliminary tests with mesenchymal stem cells demonstrated that the hydrogel can be actively remodelled, as evaluated by stiffness parameters at day one and seven of incubation. Growth factors (GFs) affect cellular fate and behaviour, and storage, presentation and administration of such chemokines can be critical for certain cellular applications. Due to the high anionic charge density of heparin, starPEG‐heparin hydrogels are known to reversibly immobilise several GFs and thereby might mimic the GF reservoir of the extra cellular matrix. Thus, transport processes of GFs with low and high heparin affinity inside these hydrogels were analysed by fluorescence correlation spectroscopy and a bulk diffusion approach. Results indicated that diffusion constants were synergistically decreased with increasing size and heparin affinity of the diffusant. Next, the capability of endothelial cells (ECs) to self‐assemble and organise into 3D capillary networks was tested in GelMA, starPEG‐heparin and Matrigel hydrogels. Only starPEG‐heparin hydrogels allowed the formation of interconnected capillaries in macroscopic hydrogel samples. However, as it is widely used to test for pro‐ and anti‐angiogenic agents, the 2D Matrigel angiogenesis assay was included for subsequent co‐culture experiments of ECs and fibroblasts in order to investigate how the stromal cells influence the formation of endothelial networks. For a detailed characterisation of 3D structures, a conventionally applied 2D method (Maximum Intensity Projection for 3D reconstructed images, MIP) was compared to an optimised 3D analysing tool. As a result, it was discovered that MIP analysis did not allow for an accurate determination of 3D endothelial network parameters, and can result in misleading interpretations of the data set. Indirect co‐cultures of hydrogel‐embedded ECs with a 2D layer of fibroblasts showed that fibroblast‐derived soluble factors, including stromal cell‐derived factor 1 and interleukin 8, affected endothelial network properties. However, only co‐encapsulation of ECs and fibroblasts in starPEG‐heparin hydrogel discs revealed remarkable changes in endothelial network parameters between CAF and NPF samples. In detail, the total length and branching of the capillaries was increased. For two donor pairs, the diameter of capillaries was decreased in CAF samples compared to NPF samples, underlining the high physiological relevance of this model. In contrast, significant differences in 2D Matrigel assays were not detected between, CAF, NPF and control (ECs only) samples. In summary, a 3D angiogenesis co‐culture system was successfully developed and used to characterise stromal‐endothelial interactions in detail. The combination of advanced biomaterials (starPEG‐heparin) and 3D analysing techniques goes beyond conventional 2D in vitro cancer research, and opens new avenues for the development of more complex models to further improve the acquisition of more biologically relevant data.

This thesis focuses on investigating the stability, dynamics and physical mechanisms of thermocapillary flows undergoing phase change by means of direct numerical simulations and experiments. The novelty of the general approach developed in this work lies in the fact that the problems under consideration are addressed with novel fully-coupled transient two-phase flow models in 3D. Traditional simplifications are avoided by accounting for deformable interfaces and by addressing advection-diffusion mechanisms not only in the liquid but also in the gas. This strategy enables a realistic investigation of the interface energy and mass transfer at a local scale for the first time. Thorough validations of the models against theory and experiments are presented. The thesis encompasses three situations in detail: liquid layers in saturated environments, liquid layers in unsaturated environments and evaporation of liquid droplets. Firstly, a model grounded in the volume-of-fluid method is developed to study the stability of laterally-heated liquid layers under saturated environments. In this configuration, the planar layer is naturally vulnerable to the formation of an oscillatory regime characterized by a myriad of thermal wave-like patterns propagating along the gas-liquid interface, i.e. hydrothermal waves. The nonlinear growth of the instabilities is discussed extensively along with the final bulk flow for both the liquid and gas phases. Previously unknown interface deformations, i.e. physical waves, induced by, and enslaved to, the hydrothermal waves are reported. The mechanism of heat transfer across the interface is found to contradict previous single-phase studies since the travelling nature of the hydrothermal waves leads to maximum heat fluxes not at the points of extreme temperatures but somewhere in between. The model for saturated environments is extended in a second stage to assess the effect of phase change in the hydrothermal waves for the first time. New numerical results reveal that evaporation affects the thermocapillary instabilities in two ways: the latent energy required during the process tends to inhibit the hydrothermal waves while the accompanying level reduction enhances the physical waves by minimizing the role of gravity. Interestingly, the hydrothermal-wave-induced convective patterns in the gas decouple the interface vapour concentration with that in the bulk of the gas leading to the formation of high (low) concentrations of vapour at a certain distance above interface cold (hot) spots. At the interface the behavior is the opposite. The phase-change mechanism for stable layers is also discussed. The Marangoni effect plays a major role in the vapour distribution and local evaporation flux and can lead to the inversion of phase-change process, i.e. the thermocapillary flow can result into local condensation in an otherwise evaporating liquid layer. The third problem discussed in this thesis concerns with the analysis of evaporating sessile droplets by means of both experiments and 3D numerical modeling. An experimental apparatus is designed to study the evaporation process of water droplets on superheated substrates in controlled nitrogen environments. The droplets are simultaneously recorded with a CCD camera from the side and with an infrared camera from top. It is found that the contact line initially remains pinned for at least 70% of the time, period after which its behaviour changes to that of the stick-slip mode and the drop dries undergoing contact line jumps. For lower temperatures an intermediate stage has been observed wherein the drop evaporates according to a combined mode. The experimental work is complemented with numerical simulations. A new model implementing the diffuse-interface method has been developed to solve the more complex problems of this configuration, especially those associated with the intricate contact-line dynamics. Further insights into the two-phase flow dynamics have been provided as well as into the initial transient stage, in which the Marangoni effect has been found to play a major role in the droplet heating. For the first time, a fully-coupled two-phase direct numerical simulations of sessile drops with a moving contact line has been performed. The last part of this work has been devoted to the investigation of three-dimensional phenomena on drops with irregular contact area. Non-sphericity leads to complex three-dimensional drop shapes with intricate contract angle distributions along the triple line. The evaporation rate is found to be affected by 3D features as well as the bulk flow, which become completely non-axisymmetric. To the best of our knowledge, this work is the first time that three-dimensional two-phase direct numerical simulations of evaporating sessile drops have been undertaken.

När ett nytt plagg utvecklas provas det oftast av endast i grundstorlek, trots att det ska produceras i flera storlekar. På grund av detta är det svårt att veta om plaggets passform kommer att se likadan ut i alla storlekar. Denna studie genomförs med syftet att utvärdera möjligheten att utföra avprovningar av samtliga produktionsstorlekar virtuellt med hjälp av ett 3D-program. Studien görs i samarbete med ett företag, vars måttlistor utvärderas för att sedan användas i studien. Två utvalda herrplagg från företaget, en skjorta och en jacka, sys upp och provas av fysiskt på provpersoner, samt virtuellt i Lectra 3D Prototyping, där de provas av på avatarer justerade till samma kroppsmått som provpersonerna. Likheten mellan avprovningsmetoderna analyseras med hjälp av foton för att utvärdera om 3D-programmet ger en tillförlitlig bild av de verkliga plaggens passform. Tidigare studier har bekräftat att detta fungerar i grundstorlek, men inte hur resultatet blir i övriga storlekar. Studien visar att avprovningar i olika storlekar ger samma resultat som i grundstorlek, med villkoret att avatarerna är skapade på ett sätt som gör det möjligt att klä dem på ett korrekt sätt. Metoden kan användas som ett komplement till fysiska avprovningar i grundstorlek.

This thesis contributes to knowledge by describing two novel methods to calculate 3D blood velocity and flow within the heart using 3D colour Doppler images. The principal goal of both methods was to overcome the main limitation of Doppler systems which is that the Doppler effect only measures one component of the velocity (parallel to the beam direction). For that reason, measured velocity and calculated flow depend on the angle between the beam direction and the flow. The first method was developed to reconstruct 3D intracardiac velocity vector fields. This is the first time that such vector fields have been obtained from 3D colour Doppler images. The novelty of the proposal lies not only in the 3D velocity reconstruction, but also 1) a new noise model for colour Doppler images was proposed which improves the realism of simulation studies, 2) an efficient patch-wise implementation was introduced and 3) ventricle wall motion was used to enable full ventricular coverage. Based on simulations minimum acquisition requirements for accurate reconstruction were established. These requirements were: view angles over 20 degrees and noise below 10% of the Doppler maximum velocity. The method was tested on healthy volunteers and on paediatric patients and an accuracy of 15% compared to flow Magnetic Resonance Imaging (MRI) was obtained, when acquisition and data conditions were close to the optimum range. The second method proposes an algorithm to calculate angle-independent flow rates through surfaces within the heart and vessels. Built on the Gauss’s theorem, this method enables to increase coverage beyond the Field of View (FoV) of individual colour Doppler images by combining images acquired from multiple views. The method was validated in patients with Hypoplastic Left Heart Syndrome. Results were compared with the current clinical gold standard measurement of flow MRI, agreeing on flow values and volumes to less than 10%. The novel methods proposed in this thesis have shown encouraging results using volunteer and patient data. I hope that the methods proposed will in the future be able to offer advanced flow measurements using echo. The ability to improve the information available from echo imaging, due to its ease of use and cost effective nature, has the potential for widespread improvements in clinical care.

Three-dimensional (3D) non-contact optical methods for surface inspection are of significant interest to many industrial sectors. Many aspects of manufacturing processes have become fully automated resulting in high production volumes. However, this is not necessarily the case for surface defect inspection. Existing human visual analysis of surface defects is qualitative and subject to varying interpretation. Automated 3D non-contact analysis should provide a robust and systematic quantitative approach. However, different 3D optical measurement technologies use different physical principles, interact with surfaces and defects in diverse ways, leading to variation in measurement data. Instrument s native software processing of the data may be non-traceable in nature, leading to significant uncertainty about data quantisation. Sub-millimetric level surface defect artefacts have been created using Rockwell and Vickers hardness testing equipment on various substrates. Four different non-contact surface measurement instruments (Alicona InfiniteFocus G4, Zygo NewView 5000, GFM MikroCAD Lite and Heliotis H3) have been utilized to measure different defect artefacts. The four different 3D optical instruments are evaluated by calibrated step-height created using slipgauges and reference defect artefacts. The experimental results are compared to select the most suitable instrument capable of measuring surface defects in robust manner. This research has identified a need for an automatic tool to quantify surface defect and thus a mathematical solution has been implemented for automatic defect detection and quantification (depth, area and volume) in 3D. A simulated defect softgauge with a known geometry has been developed in order to verify the implemented algorithm and provide mathematical traceability. The implemented algorithm has been identified as a traceable, highly repeatable, and high speed solution to quantify surface defect in 3D. Various industrial components with suspicious features and solder joints on PCB are measured and quantified in order to demonstrate applicability.

In this thesis a new three–dimensional (3D) vector radiative transfer model, the Solver for Polarized Atmospheric Radiative Transfer Applications (SPARTA) is introduced, validated against benchmark results, and applied to scientific problems. SPARTA employs the statistical forward Monte Carlo technique for efficient column–response pixel–based radiance calculations comprising polarization for 3D inhomogeneous cloudless and cloudy atmospheres. By means of SPARTA, two scientific issues in the field of radiative transfer are investigated. A sensitivity study has been conducted to illustrate the errors introduced by neglecting the effects of polarization in radiation simulations. Two atmospheric scenarios have been considered: a pure one–dimensional (1D) Rayleigh atmosphere and two–dimensional (2D) realistic inhomogeneous dust fields. In case of a purely molecular atmosphere, these errors strongly depend on molecular anisotropy, isotropic reflection, and more importantly, on single scattering albedo and optical thickness (saturation occurs for τ close to 1). Overall errors in the reflected field range up to about 10.5%. On the other hand, for rather high optical thickness, the bias induced by ignoring polarization for realistic inhomogeneous atmospheres is negligible (less than 1%). In addition, solar radiative transfer simulations for LIDAR–measured fields of optical properties of Saharan dust have been performed in order to quantify the effects induced by neglecting the horizontal photon transport and internal inhomogeneities (3D radiative effects) in radiance simulations including polarization. Results are presented for two exemplary mineral dust fields constructed from LIDAR observations. For each case, three radiative calculations are investigated: a 1D calculation according to the plane–parallel (1D mode); an Independent Pixel Approximation (IPA mode); and the 2D mode. The differences in domain–averaged normalized radiances of reflection and transmission are insignificant between the 1D or IPA and 2D calculation modes. However, local differences were observed since extinction is hinge on horizontal spatial variability. In the areas with large spatial variability in optical thickness, the radiance fields of the 2D mode differ about ±20% for the first and second Stokes elements (I, Q) from the fields of the 1D mode. This work points to a brand–new field: the quantification of the sensitivity of polarization to 3D radiative effects.