Doctor of Philosophy

dissertationVisualizing surfaces is a fundamental technique in computer science and is frequently used across a wide range of fields such as computer graphics, biology, engineering, and scientific visualization. In many cases, visualizing an interface between boundaries can provide meaningful analysis or simplification of complex data. Some examples include physical simulation for animation, multimaterial mesh extraction in biophysiology, flow on airfoils in aeronautics, and integral surfaces. However, the quest for high-quality visualization, coupled with increasingly complex data, comes with a high computational cost. Therefore, new techniques are needed to solve surface visualization problems within a reasonable amount of time while also providing sophisticated visuals that are meaningful to scientists and engineers. In this dissertation, novel techniques are presented to facilitate surface visualization. First, a particle system for mesh extraction is parallelized on the graphics processing unit (GPU) with a red-black update scheme to achieve an order of magnitude speed-up over a central processing unit (CPU) implementation. Next, extending the red-black technique to multiple materials showed inefficiencies on the GPU. Therefore, we borrow the underlying data structure from the closest point method, the closest point embedding, and the particle system solver is switched to hierarchical octree-based approach on the GPU. Third, to demonstrate that the closest point embedding is a fast, flexible data structure for surface particles, it is adapted to unsteady surface flow visualization at near-interactive speeds. Finally, the closest point embedding is a three-dimensional dense structure that does not scale well. Therefore, we introduce a closest point sparse octree that allows the closest point embedding to scale to higher resolution. Further, we demonstrate unsteady line integral convolution using the closest point method

Novel Discretization Schemes for the Numerical Simulation of Membrane Dynamics

Motivated by the demands of simulating flapping wings of Micro Air Vehicles, novel numerical methods were developed and evaluated for the dynamic simulation of membranes. For linear membranes, a mixed-form time-continuous Galerkin method was employed using trilinear space-time elements, and the entire space-time domain was discretized and solved simultaneously. For geometrically nonlinear membranes, the model incorporated two new schemes that were independently developed and evaluated. Time marching was performed using quintic Hermite polynomials uniquely determined by end-point jerk constraints. The single-step, implicit scheme was significantly more accurate than the most common Newmark schemes. For a simple harmonic oscillator, the scheme was found to be symplectic, frequency-preserving, and conditionally stable. Time step size was limited by accuracy requirements rather than stability. The spatial discretization scheme employed a staggered grid, grouping of nonlinear terms, and polygon shape functions in a strong-form point collocation formulation. Validation against existing experimental data showed the method to be accurate until hyperelastic effects dominate

Performing the digital: performativity and performance studies in digital cultures

How is performativity shaped by digital technologies - and how do performative practices reflect and alter techno-social formations? "Performing the Digital" explores, maps and theorizes the conditions and effects of performativity in digital cultures. Bringing together scholars from performance studies, media theory, sociology and organization studies as well as practitioners of performance, the contributions engage with the implications of digital media and its networked infrastructures for modulations of affect and the body, for performing cities, protest, organization and markets, and for the performativity of critique. With contributions by Marie-Luise Angerer, Timon Beyes, Scott deLahunta and Florian Jenett, Margarete Jahrmann, Susan Kozel, Ann-Christina Lange, Oliver Leistert, Martina Leeker, Jon McKenzie, Sigrid Merx, Melanie Mohren and Bernhard Herbordt, Imanuel Schipper and Jens Schröter

THE WHOLE NAKED TRUTH OF OUR LIVES: LESBIAN-FEMINIST PRINT CULTURE FROM 1969 THROUGH 1989

During the 1970s and the 1980s, lesbian-feminists created a vibrant lesbian print culture, participating in the creation, production, and distribution of books, chapbooks, journals, newspapers, and other printed materials. This extraordinary output of creative material provides a rich archive for new insights about the Women's Liberation Movement (WLM), gay liberation (the LGBT movement), and recent U.S. social history. In The Whole Naked Truth of Our Lives, I construct and analyze historical narratives of lesbian-feminist publishers in the United States between 1969 and 1989. Interdisciplinary in its conception, design, and execution, The Whole Naked Truth of Our Lives is the only sustained examination of lesbian print culture during the 1970s and 1980s; it extends the work of Simone Murray on feminist print culture in the United Kingdom as well as the work of literary scholars Kim Whitehead, Kate Adams, Trysh Travis, Bonnie Zimmerman, and Martha Vicinus, and historians Martin Meeker, Marcia Gallo, Rodger Streitmatter, Abe Peck, John McMillian, and Peter Richardson. From archival material, including correspondence, publishing ephemera such as flyers and catalogues, and meeting notes, oral history interviews, and published books, I assemble a history of lesbian-feminist publishing that challenges fundamental ideas about the WLM, gay liberation, and U.S. social history as well as remapping the contours of current historical and literary narratives. In the excitement of the WLM, multiple feminist practices expressed exuberant possibilities for a feminist revolution. Cultural feminism and lesbian separatism were vibrant expressions of the WLM; they were not antagonistic to radical feminism or liberal feminism but rather complementary and overlapping. Economic restructuring in the United States (e.g. globalization, decreasing governmental support for the arts, and neoliberalism) tempered visions for a lesbian-feminist revolution. Lesbian-feminist publishers experienced economic restructuring as it unfolded and actively discussed the political, economic, and theoretical implications. The strategies and responses of lesbian-feminist publishers demonstrate the effects of and resistances to these macro-economic forces. Examining the economics of book publishing explains how literary artists and other creative intellectuals support themselves in capitalist economies, illuminates broader intellectual and cultural currents, and suggests how broader economic trends in the United States interacted with cultural production