Global ETD Search

1	Access Methods for Temporal Databases Stantic, Bela, n/a January 2005 (has links) A Temporal database is one that supports some aspect of time distinct from user defined time. Over the last two decades interest in the field of temporal databases has increased significantly, with contributions from many researchers. However, the lack of efficient access methods is perhaps one of the reasons why commercial RDBMS vendors have been reluctant to adopt the advances in temporal database research. Therefore, an obvious research question is: can we develop more robust and more efficient access methods for temporal databases than the existing ones? This thesis attempts to address this question, and the main contributions of this study are summarised as follows: We investigated different representations of 'now' and how the modelling of current time influences the efficiency of accessing 'now relative' temporal data. A new method, called the 'Point' approach, is proposed. Our approach not only elegantly models the current time but also significantly outperforms the existing methods. We proposed a new index structure, called a Virtual Binary tree (VB-tree), based on spatial representation of interval data and a regular triangular decomposition of this space. Further, we described a sound and complete query algorithm. The performance of the algorithm is then evaluated both asymptotically and experimentally with respect to the state-of-the-art in the field. We claim that the VB-tree requires less space and uses fewer disk accesses than the currently best known structure - the RI-tree. Temporal database point approach virtual binary tree index structure query algorithm
2	Valuation and Optimal Strategies in Markets Experiencing Shocks Dyrssen, Hannah January 2017 (has links) This thesis treats a range of stochastic methods with various applications, most notably in finance. It is comprised of five articles, and a summary of the key concepts and results these are built on. The first two papers consider a jump-to-default model, which is a model where some quantity, e.g. the price of a financial asset, is represented by a stochastic process which has continuous sample paths except for the possibility of a sudden drop to zero. In Paper I prices of European-type options in this model are studied together with the partial integro-differential equation that characterizes the price. In Paper II the price of a perpetual American put option in the same model is found in terms of explicit formulas. Both papers also study the parameter monotonicity and convexity properties of the option prices. The third and fourth articles both deal with valuation problems in a jump-diffusion model. Paper III concerns the optimal level at which to exercise an American put option with finite time horizon. More specifically, the integral equation that characterizes the optimal boundary is studied. In Paper IV we consider a stochastic game between two players and determine the optimal value and exercise strategy using an iterative technique. Paper V employs a similar iterative method to solve the statistical problem of determining the unknown drift of a stochastic process, where not only running time but also each observation of the process is costly. American options optimal stopping game options jump diffusion jump to default free-boundary problems early exercise premium integral equation parabolic pde convexity sequential testing fixed-point approach Probability Theory and Statistics Sannolikhetsteori och statistik
3	Opportunities and Challenges of Citywide Main Street Programs: Examining the Urban Environment, Coordinating Structures and Political Realities in the Application of the Four Point Approach Rinn, Ryan 03 May 2012 (has links) The Main Street Four Point Approach to commercial revitalization has been applied successfully in thousands of communities across the U.S. Starting in 1995, citywide coordinated programs began applying the balanced points of organization, design, economic restructuring and promotion to urban environments. This thesis focuses on the opportunities and challenges present in five citywide Main Street programs in Boston, Baltimore, Washington D.C., Orlando and Portland through quantitative inquiry and interviews with program administrators. This thesis discusses density, capacity, volunteerism, vernacular culture, and politics as emergent themes of the urban application of the Main Street Approach and recommends expanding the breadth of definition and flexibility of each of the Four Points as to be more applicable and successful in the citywide context. Commercial Revitalization Main Street Approach Four Point Approach Density Capacity Volunteerism Vernacular Culture Social Capital Politics Organization Promotion Economic Restructuring Design Urban Commercial Revitalization Social and Behavioral Sciences Urban Studies and Planning
4	Comparing the Dominance Approach to the Ideal-Point Approach in the Measurement and Predictability of Personality Broadfoot, Alison Ann 08 July 2008 (has links) No description available. Behaviorial Sciences Business Community Management Occupational Psychology Organizational Behavior Personality Psychological Tests Psychology Statistics Personality Measurement Measurement Models Unfolding Models Item Response Theory Dominance Models Ideal-Point Approach Dominance Approach Generalized Graded Unfolding Models Generalized Partial Credit Models Personnel Selection
5	The Incremental Scheme - From Method Development to Applications in Chemistry Fiedler, Benjamin 15 October 2020 (has links) In this thesis, several development steps for the incremental method are presented. At first, the extension of the incremental scheme to other quantities than the energy is advanced in terms of molecular dipole moments. In this context, a revised error correction as well as the template localization for the treatment of aromatic systems are introduced. As a second enhancement, a new implementation of the template localization ensures a higher stability of this algorithm step and, thus, of the incremental scheme. Finally, pair natural orbitals (PNOs) are utilized in the incremental method with the aim of an increased efficiency. The PNO approach is re-assessed in context of the incremental expansion leading to both small incremental and PNO local errors for reaction, intermolecular interaction and cluster binding energies. The higher efficiency due to the twofold reduction of the computational efforts by the PNO and the incremental approaches is demonstrated for molecular clusters. Additionally, the complete basis set (CBS) limit is targetted by using the efficient MP2-based focal-point approach to the incremental scheme (with and without PNOs). Finally, based on these improvements of the performance, the PNO-based incremental scheme is applied to support a computational study regarding the modelling of the reaction mechanism for the base-catalyzed twin polymerization. info:eu-repo/classification/ddc/540 ddc:540 info:eu-repo/classification/ddc/541 ddc:541

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