Autonomous navigation accuracy using simulated horizon sensor and sun sensor observations

A relatively simple autonomous system which would use horizon crossing indicators, a sun sensor, a quartz oscillator, and a microprogrammed computer is discussed. The sensor combination is required only to effectively measure the angle between the centers of the Earth and the Sun. Simulations for a particular orbit indicate that 2 km r.m.s. orbit determination uncertainties may be expected from a system with 0.06 deg measurement uncertainty. A key finding is that knowledge of the satellite orbit plane orientation can be maintained to this level because of the annual motion of the Sun and the predictable effects of Earth oblateness. The basic system described can be updated periodically by transits of the Moon through the IR horizon crossing indicator fields of view

Race Patriots: Black Poets, Transnational Identity, and Diasporic Versification in the United States Before the New Negro

This dissertation explores the contributions of black poets in the United States before the New Negro / Harlem Renaissance Movement. Specifically, it focuses on their role in creating and maintaining a tradition of regional transnationalism in their verses that celebrates their African ancestry. I contend that these poets are best understood as “race patriots”; that is, they at once sought inclusion within the nation-state in the form of full citizenship, yet recognized allegiances beyond the nation-state on account of race through a recognition of shared African ancestry across borders. Their verses point to a shared kinship – be it through common condition, culture, or politics – present within black literary thought, and thus within black communities, long before the New Negro. By extension, I advocate for a reimagining of the significance of nineteenth and eighteenth century poets within African American literature. The dissertation challenges the accusation that black poetry in the United States was wholly assimilative or parroting, instead positing the strategic mimicry of neoclassicism and romanticism as subversive and in direct conversation (and contention) with racist Enlightenment discourses. The dissertation considers a range of poets of varying repute: George Moses Horton, Phillis Wheatley, James Madison Bell, Joshua McCarter Simpson, George Boyer Vashon, Frances Ellen Watkins Harper, James Monroe Whitfield, T. Thomas Fortune, Henrietta Cordelia Ray, George Clinton Rowe, and Paul Laurence Dunbar. The poets considered challenge traditional notions of patriotism and allegiance by championing rights for those of like ancestry within and across national boundaries. In turn, the study is indicative of how a patriotic nationalism can coexist with a Pan-African sensibility through a sustained critique of (global) white hegemony. The study explores how these poets evince their race patriotism through a variety of means, including Ethiopianism, salvation-liberation ideology, and usage of tribute poems to honor figures, events, and places within the diaspora (e.g. Haiti, Jamaican Emancipation, Joseph Cinqué, Vincent Ogé). Through their content, I argue that the poets engage in a project of historical reclamation and history building that demonstrates their awareness of their distinct identities within and beyond the nation-state

Simulation Studies of the NLC with Improved Ground Motion Models

The performance of various systems of the Next Linear Collider (NLC) have been studied in terms of ground motion using recently developed models. In particular, the performance of the beam delivery system is discussed. Plans to evaluate the operation of the main linac beam-based alignment and feedback systems are also outlined.Comment: Submitted to XX International Linac Conferenc

Understanding the Impact of Differentiation and Unitization on the Perceptual Features Learned During Category Training

Thesis (Ph.D.) - Indiana University, Psychological and Brain Sciences/Cognitive Sciences, 2015Perceptual representations are a foundational aspect of all cognitive processes that involve input from the external environment. Yet there is ample evidence that these perceptual representations are altered by experience in systematic ways. This work focuses on understanding how perceptual representations are modified through two perceptual learning processes, differentiation and unitization, in the context of category learning. First, we review the empirical evidence for perceptual learning with a focus on the evidence for unitization and differentiation processes in the context of category learning. This section also includes a discussion of the role of differentiation and unitization learning processes in four computational models of perceptual learning. Second, we present a series of four experiments that measure the change in perceptual representations after learning category structures designed to promote differentiation and unitization in perceptual learning. Third, we investigate the impact of these category structures on the features inferred by a model that incorporates both differentiation and unitization perceptual learning processes. Fourth, we develop a modeling framework to directly compare the fit of computational models that assume different perceptual representations to the empirical results. Finally, we conclude by considering the implications and limits of these results

Beam-based Feedback Simulations for the NLC Linac

Extensive beam-based feedback systems are planned as an integral part of the Next Linear Collider (NLC) control system. Wakefield effects are a significant influence on the feedback design, imposing both architectural and algorithmic constraints. Studies are in progress to assure the optimal selection of devices and to refine and confirm the algorithms for the system design. We show the results of initial simulations, along with evaluations of system response for various conditions of ground motion and other operational disturbances.Comment: 3 pages. Linac2000 conferenc

Inflatable holding fixture permits X-rays to be taken of inner weld areas

Inflatable rubber gland positions and holds X ray film in positive contact with inner weld areas of mainfold torus assemblies for verifying the weld quality. The gland is constructed to conform to the inside diameter of the manifold torus

Measurement of Magnetization Dynamics in Single-Molecule Magnets Induced by Pulsed Millimeter-Wave Radiation

We describe an experiment aimed at measuring the spin dynamics of the Fe8 single-molecule magnet in the presence of pulsed microwave radiation. In earlier work, heating was observed after a 0.2-ms pulse of intense radiation, indicating that the spin system and the lattice were out of thermal equilibrium at millisecond time scale [Bal et al., Europhys. Lett. 71, 110 (2005)]. In the current work, an inductive pick-up loop is used to probe the photon-induced magnetization dynamics between only two levels of the spin system at much shorter time scales (from ns to us). The relaxation time for the magnetization, induced by a pulse of radiation, is found to be on the order of 10 us.Comment: 3 RevTeX pages, including 3 eps figures. The paper will appear in the Journal of Applied Physics as MMM'05 conference proceeding