In order to predict the behavior of bubbly flows, it is necessary to know the three dimensional profiles of the bubbles present in the flow. With advancements in the field of flow visualization, accurate reconstruction of the bubble shape has become necessary. The PIV and the SIV techniques, used to acquire images of particles and bubbles, have been found to be extremely useful in this regard. The study, development, implementation, applications and limitations of a unique reconstruction technique applied to various regular and irregular bubble shapes, using the two orthogonal projections of the three-dimensional bubble profiles as captured by the SIV cameras are presented here. The technique is a blend of neural networks, combinatorial optimization and advanced computer aided design methods. The technique involves the robustness and ruggedness of the neural network approach and the flexibility and reliability of advanced computer aided design methods. The technique uses a well-known problem in neural networks and combinatorial optimization known as the Traveling Salesman Problem approach to identify the bubble boundaries on the images. An optimization solution technique known as the Simulated Annealing technique is employed to solve the Traveling Salesman Problem and obtain the bubble profiles. These results are employed to reconstruct bubble shapes using NURBS computer aided design software. Two main applications of this technique are demonstrated and the results are found to be promising. The first application included the calculation of the void fraction at a particular depth of the channel/ pipe and at a particular radius of the channel. The second application was Lagrangian tracking of bubbles, wherein the centroids of the bubbles were tracked between image frames to determine the linear and transverse velocities of the bubbles. This technique has shown scope for development including the development as integrated bubble surface reconstruction software and advanced modifications at various levels for efficient and accurate reconstruction.

Vishet som fenomen har en lång historia, dock har begreppet under de senaste åren uppmärksammats allt mer av empirisk forskning. Det råder oenigheter kring fenomenets innebörd. Många studier visar dock att vishet kännetecknas av kognitiva och reflekterande dimensioner - precis som i Ardelts teori där vishet förklaras genom kognitiva, affektiva och reflekterande egenskaper. Denna studie utgår från Ardelts teori. En enkätundersökning med 110 deltagare genomfördes med syftet att utforma ett för arbetslivet modifierat vishetsformulär. Dessutom ämnade studien jämföra kön, ålder och privat respektive kommunal sektor. Resultatet visade hög korrelation mellan det modifierade vishetsformuläret (ViA) och Ardelts tredimensionella visdomsskala (3D-WS). Dessutom visade resultatet att privat sektor erhöll signifikant högre poäng än kommunal sektor i 3D-WS, samt att kvinnor i snitt fick högre poäng än män. Åldersskillnader påvisades inte. Studiens brister i form av bland annat representativitet, antalet deltagare och utformningen av enkäten diskuterades.

Objective: To evaluate three-dimensional position of the TMJ condyle within the glenoid fossa in different types of skeletal patterns. Materials and methods: Ninety CBCT images were consecutively selected and divided into skeletal class I, class II and class III. The images were analyzed locating landmarks in the different areas of the condyle and glenoid fossa. All landmarks presented acceptable reliability. The mean results were compared using ANOVA and Bonferroni post-hoc test (p < 0.05). Results: There was a tendency for the anterior joint space to be smaller than the posterior joint space. Statistical analysis, however, evidenced no significant differences between the anterior, superior and posterior joint spaces and the different skeletal patterns or between sides. Conclusion: There was non-concentricity of the condyle for all the groups studied, and no particular direction was statistically significantly favored. It is unclear whether the differences found would be clinically significant, considering anatomical individual variations.

Introduction. Executive function refers to the top-down neurocognitive processes involved in flexible, goal-oriented behavior. A number of studies have shown positive effects of EF training. The overall aim of these studies was to explore the neurocognitive processes that support the development of EF by understanding how EF training works and what the active ingredients are. Particular interest was in isolating the role of reflection in EF training to understand its top-down affect on ACC-mediated conflict detection. Method. In Exp. 1 the neural markers of EF were explored by comparing ERPs of preschoolers who passed the DCCS and preschoolers who failed. Exp. 2 represents an attempt to replicate the key findings of Kloo & Perner, (2003, Exp. 2) that reflection training improves preschoolers’ performance on the DCCS and demonstrates far transfer. A shortened version of the training protocol was also tested (Exp. 3). In Exp. 4, the neural correlates of reflection training in preschoolers were explored by examining changes in the neural marker of EF found in Exp. 1. Results. In Exp. 1, the N2 amplitude was smaller (less negative) for children who passed the DCCS and were able to efficiently resolve the conflict in the stimuli than for children who failed and were unable to resolve the conflict. Exp. 2 replicated the findings of Kloo & Perner, (2003, Exp. 2) even using a brief (15 min) intervention targeting reflection (Exp. 3). In Exp. 4, one brief session of reflection training made children who initially failed the DCCS look like children who initially passed at both the behavioral and neural level (reduced N2 amplitude). Conclusion. Results suggest that reflective processing facilitates the development of EF in young children by teaching them to notice conflict, reflect on it, and formulate rules for resolving it, resulting in the down-regulation of ACC-mediated conflict detection.

Introduction. Executive function refers to the top-down neurocognitive processes involved in flexible, goal-oriented behavior. A number of studies have shown positive effects of EF training. The overall aim of these studies was to explore the neurocognitive processes that support the development of EF by understanding how EF training works and what the active ingredients are. Particular interest was in isolating the role of reflection in EF training to understand its top-down affect on ACC-mediated conflict detection. Method. In Exp. 1 the neural markers of EF were explored by comparing ERPs of preschoolers who passed the DCCS and preschoolers who failed. Exp. 2 represents an attempt to replicate the key findings of Kloo & Perner, (2003, Exp. 2) that reflection training improves preschoolers’ performance on the DCCS and demonstrates far transfer. A shortened version of the training protocol was also tested (Exp. 3). In Exp. 4, the neural correlates of reflection training in preschoolers were explored by examining changes in the neural marker of EF found in Exp. 1. Results. In Exp. 1, the N2 amplitude was smaller (less negative) for children who passed the DCCS and were able to efficiently resolve the conflict in the stimuli than for children who failed and were unable to resolve the conflict. Exp. 2 replicated the findings of Kloo & Perner, (2003, Exp. 2) even using a brief (15 min) intervention targeting reflection (Exp. 3). In Exp. 4, one brief session of reflection training made children who initially failed the DCCS look like children who initially passed at both the behavioral and neural level (reduced N2 amplitude). Conclusion. Results suggest that reflective processing facilitates the development of EF in young children by teaching them to notice conflict, reflect on it, and formulate rules for resolving it, resulting in the down-regulation of ACC-mediated conflict detection.

Šiais laikais vis daugiau domimasi daugiamačių duomenų aproksimavimo teorija. Daugiamatėje erdvėje aproksimavimo teorija palčiai kur taikoma, pavyzdžiui, skaitinių metodų analizėje, bangų analizėje, signalų apdorojime, įvairiose informacinių technologijų sistemose, kompiuterių grafikoje, astronomijoje, naftos klodų tyrinėjime. Ši sritis viliojanti, nes didelė dalis klasikinės matematikos sunkiai pritaikoma daugiamačiams uždaviniams analizuoti. Taigi senoms problemoms spręsti reikalingi nauji įrankiai. Funkcijų aproksimavimo uždavinių gausu įvairiose matematikos, fizikos ir technikos srityse. Gausu ir jų sprendimų būdų bei metodų. Nesunkiai šie uždaviniai sprendžiami, kai funkcija priklauso nuo vieno ar dviejų kintamųjų. Tačiau realiame gyvenime naudojamos funkcijos turi daug daugiau nežinomųjų. Didėjant kintamųjų skaičiui uždavinio sudėtingumas taip pat auga. Pavyzdžiui, kai funkcija priklauso nuo vieno kintamojo, ją galima pavaizduoti plokštumoje kaip kreivę. Dviejų kintamųjų funkciją atitinka paviršius, nubrėžtas trimatėje erdvėje. Funkcijų, kurios priklauso nuo trijų ir daugiau kintamųjų, vaizdavimas jau sukelia problemų, nes žmogus nebegali suvokti didesnio matumo erdvės. Kadangi trimatę erdvę galima pavaizduoti plokštumoje, manoma, kad panašiu principu keturmatę erdvę galima pavaizduoti trimatėje, o šią vėl plokštumoje. Jei pavyktų sugalvoti tokį metodą, erdvės matumas nebesukeltų problemų. Visgi trijų kintamųjų funkciją bandoma vaizduoti dviem būdais: 1. pateikti... [toliau žr. visą tekstą] / This Master‘s work covers a mathematical analysis system which can visualize multivariate data layers, approximate multi-dimensional functions by polynomials, estimate approximation accuracy and present few the most effective aproximation models. Multivariate approximation theory is an increasingly active research area today. It encompasses a wide range of tools for multivariate approximation such as multi-dimensional splines and finite elements, shift-invariant spaces and radial-basis functions. Approximation theory in the multivariate setting has many applications including numerical analysis, wavelet analysis, signal processing, geographic information systems, computer aided geometric design and computer graphics. The field is fascinating since much of the mathematics of the classical univariate theory does not straightforwardly generalize to the multivariate setting, so new tools are required. Graphs of one variable functions are frequantly displayed as curves, bivariate functions - as contour plots. In generally it is very hard to display or realize function in the multivariate setting. However, some efforts have been made to render functions of precisely three variables. Two obvious approaches suggest themselves: 1. Display a number of cross sections where one of the variables is held constant, or, 2. display contour surfaces where the value of function equals some constant. We will use the first method modification in this Master‘s work. All function variables except... [to full text]

Šiame darbe apžvelgtos įvairios trimatės galerijos ir jų kūrimo principai. Atlikta programų ir įrankių, skirtų galerijoms kurti, analizė. Atlikta VRML programavimo kalbos galimybių ir jos taikymų trimatės grafikos sistemose analizė. Supažindinama su šablonų generavimo būdais. Atlikta įskiepų, skirtų trimačių galerijų naršyklėse peržiūrai, analizė. Panaudojant ArchiCad projektavimo įrankį ir VRML kalbą, sukurtas trimatis galerijos šablonas. / This paper reviews various three – dimensional galleries and their development principles. There was made an analysis of programmes and tools, which were designed for the creation of galleries. The analysis was also made of VRLM programming language – its options and applications in three–dimensional graphics systems. This work acquaints with methods of template generation. There was made an analysis of plugins, which are intended for the viewing in the browsers of three–dimensional galleries. There was created the three–dimensional template of the gallery, by using ArchiCad and VRML design tool.

The Intrinsic Low-Dimensional Manifold (ILDM) has been adopted as an approximation to the slow manifold representing the long-term evolution of a non-linear chemical system. The computation of the slow manifold simplifies the model without sacrificing accuracy because the trajectories are rapidly attracted to it. The ILDM has been shown to be a highly accurate approximation to the manifold when the curvature of the manifold is not too large. An efficient method of calculating an approximation to the slow manifold which may be equivalent to the ILDM is presented. This method, called Functional Equation Truncation (FET). is based on the assumption that the local curvature of the manifold is negligible, resulting in a locally linearized system. This system takes the form of a set of algebraic equations which can be solved for given values of the independent variables. Two-dimensional and three-dimensional models are used to test this method. The approximations to onedimensional slow manifolds computed by FET are quite close to the corresponding ILDMs and those for two-dimensional ones seem to differ from their ILDM counterparts. / vii, 61 leaves ; 29 cm.

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The non-interacting, nonuniform electron gas exhibits simplifications in two dimensions, that are of particular interest in the application of density functional theory. The results of linear response theory for an attractive impurity in a two-dimensional gas have been shown to be surprisingly accurate even though there are bound states, and were shown to be exact in the high density limit (Zaremba et al. Phys. Rev. B, 71:125323, 2005 and Zaremba et al. Phys. Rev. Lett., 90(4):046801, 2003). The density resulting from linear response theory and the Thomas-Fermi approximation coincide in the high density limit. As an alternative to linear response theory, the Kirzhnits gradient expansion gives corrections to Thomas-Fermi in gradients of the potential. In two dimensions, all of the gradient corrections vanish at zero temperature, which is a new result presented in this work. We have performed numerical calculations which show that while Thomas-Fermi appears to be a surprisingly accurate approximation in two dimensions, it is not exact. The differences between two and three dimensions that lead to the vanishing of the gradient corrections, however, are of great interest since these may lead to better understanding and simplifications of the corresponding three-dimensional problem. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2007-11-07 09:47:00.316