Extracting surfaces, representing boundaries of objects of interest, from volumetric images, has important applications in various scientific domains, from medicine to geology. In this thesis, I introduce novel mathematical, computational, and algorithmic machinery for extraction of sheet-like surfaces (with boundary), whose boundary is unknown a-priori, a particularly important case in applications that has no convenient methods. This case of a surface with boundaries has applications in extracting faults (among other geological structures) from seismic images in geological applications. Another application domain is in the extraction of structures in the lung from computed tomography (CT) images. Although many methods have been developed in computer vision for extraction of surfaces, including level sets, convex optimization approaches, and graph cut methods, none of these methods appear to be applicable to the case of surfaces with boundary. The novel methods for surface extraction, derived in this thesis, are built on the theory of Minimal Paths, which has been used primarily to extract curves in noisy or corrupted images and have had wide applicability in 2D computer vision. This thesis extends such methods to surfaces, and it is based on novel observations that surfaces can be determined by extracting topological structures from the solution of the eikonal partial differential equation (PDE), which is the basis of Minimal Path theory. Although topological structures are known to be difficult to extract from images, which are both noisy and discrete, this thesis builds robust methods based on Morse theory and computational topology to address such issues. The algorithms have run-time complexity O(NlogN), less complex than existing approaches. The thesis details the algorithms, theory, and shows an extensive experimental evaluation on seismic images and medical images. Experiments show out-performance in accuracy, computational speed, and user convenience compared with related state-of-the-art methods. Lastly, the thesis shows the methodology developed for the particular case of surfaces with boundary extends to surfaces without boundary and also surfaces with different topologies, such as cylindrical surfaces, both important cases for many applications in medical image analysis.

With the ever growing forwarding tables of the internet and the large amount of traffic that flows through them, efficient algorithms to handle search are needed. One of these algorithms is the Multibit trie (prefix tree). The Multibit trie is a search trie that looks at several bits at a time, which is called a stride, to reduce the memory accesses for the algorithm. It is assumed that the trade-off for this is that the memory consumption will increase. To test this claim an implementation in python was written and two data sets with different sizes were used to build the Multibit trie. The two data sets that were used was the NY and the MAE-WEST data set. Search tests for different stride values were performed on the two data sets to get measurement of the average amount of memory accesses and the number of nodes were measured on different stride values. The results were that stride values 2 and 3 had less average memory accesses and less nodes than stride value 1. Stride value 6 had a significantly larger increase in nodes compared to its smaller stride values. It was concluded that stride value 2 and 3 did not follow the claim that the memory consumption does increase with larger stride values for these data sets. On these two data set no benefit was found for using stride value 1 compared to stride value 2 and 3. Furthermore stride value 6 was found to have a large increase in memory consumption for a minimal decrease in memory accesses.

The report describes the thesis project with the aim of fusing an arbitrary sequence of stereo measurements into a global 3D representation in real-time. The proposed method involves an octree-based signed distance function for representing the 3D environment, where the geomtric data is fused together using a cumulative weighted update function, and finally rendered by incremental mesh extraction using the marching cubes algorithm. The result of the project was a prototype system, integrated into a real-time stereo reconstruction system, which was evaluated by benchmark tests as well as qualitative comparisons with an older method of overlapping meshes. / <p>Examensarbetet är utfört vid Institutionen för teknik och naturvetenskap (ITN) vid Tekniska fakulteten, Linköpings universitet</p>

Time-domain methods are preferred over their frequency-domain counterparts for solving acoustic and electromagnetic scattering problems since they can produce wide- band data from a single simulation. Among the time-domain methods, time-domain surface integral equation solvers have recently found widespread use because they offer several benefits over differential equation solvers. This dissertation develops several second-kind surface integral equation solvers for analyzing transient acoustic scattering from rigid and penetrable objects and transient electromagnetic scattering from perfect electrically conducting and dielectric objects. For acoustically rigid, perfect electrically conducting, and dielectric scatterers, fully explicit marching-on-in-time schemes are developed for solving time domain Kirchhoff, magnetic field, and scalar potential integral equations, respectively. The unknown quantity (e.g., velocity potential, electric current, or scalar potential) on the scatterer surface is discretized using a higher-order method in space and Lagrange interpolation in time. The resulting system is cast in the form of an ordinary differen- tial equation and integrated in time using a predictor-corrector scheme to obtain the unknown expansion coefficients. The explicit scheme can use the same time step size as its implicit counterpart without sacrificing from the stability of the solution and is much faster under low-frequency excitation (i.e., for large time step size). In addition, low-frequency behavior of vector potential integral equations for perfect electrically conducting scatterers is also investigated in this dissertation. For acoustically penetrable scatterers, presence of spurious interior resonance modes in the solutions of two forms of time domain surface integral equations is investigated. Numerical results demonstrate that the solution of the form that is widely used in the literature is corrupted by the interior resonance modes. But, the amplitude of these modes in the time domain can be suppressed by increasing the accuracy of discretization especially in time. On the other hand, the proposed one in the combined form shows a resonance-free performance verified via numerical experiments. In addition to providing detailed formulations of these solvers, the dissertation presents numerical examples, which demonstrate the solvers’ accuracy, efficiency, and applicability in real-life scenarios.

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The college marching band provides students with opportunities that foster student development, defined as the personal growth and identity development of students due to environmental factors in higher education. However, previous research has not focused on the role of college marching band participation in student development. The goal of this study was to broaden the understanding of its student development role, enhance development experiences, and improve culture. A self-administered survey was electronically distributed to band directors through the College Band Directors National Association email list with a request to forward it to current college marching band students. The survey contained two sections: (1) Demographic information, (2) Rating college marching band’s influence on 29 student development goals, using a four-point Likert scale with the choices: strong influence, moderate influence, some influence, and no influence. Chickering and Reisser’s (1993) Seven Vectors of college student development served as a theoretical framework for the creation of goals related to college marching band situations that build and reinforce a student’s identity. Responses were analyzed by comparing groups based on demographic characteristics relevant to the research questions. Results were similar to those of previous research. Women rated college marching band participation’s importance higher than men, older students rated it higher than younger, and more-involved students rated it higher than less-involved students. Participants’ perceptions most resonated with Chickering and Reisser’s (1993) vectors Developing Competence and Developing Purpose, and resonated least with the vector Developing Integrity.

Detta arbete undersöker om de existerande algoritmerna Marching cubes och Perlin noise kan användas för att procedurellt generera terräng. Implementationen av dessa algoritmer genererar en terräng som representeras som en tredimensionell volym, för att lösa problem som kan uppkomma när terrängen representeras av ett tvådimensionellt höjdfält. Vidare parallelliseras kombinationen av dessa algoritmer och anpassas för körning på GPU, där experiment visade att parallelliseringen gav prestandaökning och således kortare genereringstider. / <p>Det finns övrigt digitalt material (t.ex. film-, bild- eller ljudfiler) eller modeller/artefakter tillhörande examensarbetet som ska skickas till arkivet.</p><p>There are other digital material (eg film, image or audio files) or models/artifacts that belongs to the thesis and need to be archived.</p>

This paper analyzes the use of Igor Stravinsky's ballet, Le Sacre de Printemps (The Rite of Spring) in shows that are in the Drum Corps International circuit since 2000. The paper is divided into five main sections that cover information about drum corps, The Rite and its music, corps that use The Rite as their show theme, corps that use The Rite as movement, and other uses of The Rite in shows. The Rite of Spring is a renowned piece of orchestral and ballet repertoire that has become increasingly popular in drum corps shows.

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<p>The prediction and characterisation of chemical and biochemical processes are fundamental tasks in computational chemistry. Small chemical systems can be characterised by the stationary points on potential energy surface and reaction paths linking them. For large biological systems, statistical sampling is required to characterising their average properties.</p> <p>This thesis presents my Ph.D. work on developing new methods to predict and characterise chemical and biological processes. Two path-finding methods for finding the minimum energy reaction path and alternative reaction paths for small gas-phase reactions have been elucidated with examples, and molecular dynamic simulations have been used to characterise the binding affinity of protein-ligand complex and the free energy of protonation processes in a protein.</p> <p>Specifically, the fast marching method (FMM) has been used to find the minimum energy path (MEP) on the potential energy surface (PES) for small gas-phase reactions. In this thesis, FMM is shown to be one of the most general and reliable surface-walking algorithms for finding the MEP. However, it is an expensive method. Some improvements have been illustrated in chapter 2 and chapter 3.</p> <p>I also proposed a new method (called QSM-NT) for finding all stationary points, accordingly all alternative reaction paths on the PES. Unlike other path-finding methods, QSM-NT overcomes the need of an initial guess of the path, and it can find all stationary points on the PES. QSM-NT has been proven to be efficient and reliable through applications on analytical PES and real chemical reaction. The difficulties and pitfalls associated with QSM-NT have been elucidated with examples.</p> <p>Molecular dynamic (MD) simulation and associated postprocessing procedures have been used to study the binding properties of caffeine-A_2A complex. The binding affinities of different binding modes have been calculated using MM/PBSA method. The binding pocket has been characterised with MM/GBSA energy decomposition. Our computational work provides significant insight to the targeted drug design of the adenosine A_2A receptor.</p> <p>The pH-dependent properties of a protein play important roles in the fundamental biological processes. The protonation states, namely, the pK_a values of ionisable residues, especially active-site residues are the prerequisites to understanding of the mechanisms of many biological processes. In this thesis, acetoacetate decarboxylase (AADase) is used as a test case for studying different types of pK_a prediction methods. Our computational results have shown that the site-site interactions from other ionisable residues are crucial to the pK_a prediction of the target residue.</p> <p>This thesis covers the range from small gas phase reaction prediction to large complex biological systems characterisation using quantum mechanical and molecular mechanical methods.</p> / Doctor of Philosophy (PhD)