<p>A detailed characterization of the proton and neutron induced radiation environment onboard Columbus and the International Space Station (ISS) has been carried out using the Geant4 Monte Carlo particle transport toolkit. Dose and dose equivalent rates, as well as penetrating particle spectra corresponding to incident trapped protons, GCR protons, SPE protons and cosmic ray albedo neutrons are presented.</p><p>These results are based on detailed Geant4 geometry models of Columbus and ISS, comprising a total of about 750 and 350 geometry volumes, respectively. Additionally, the physics models of Geant4 have been validated with respect to space radiation shielding applications. Geant4 physics configurations based on the “Binary Cascade” and “Bertini Cascade” models of hadronic reactions were found to adequately model the particle interactions of the relevant space radiation fields. Other studied Geant4 models of hadronic reactions were found to be unsatisfactory for this application.</p><p>Calculated trapped proton dose rates are found to be strongly dependent on ISS altitude. Dose rates for different locations inside the Columbus cabin are presented, as well as for different models of the incident space radiation flux. Dose rates resulting from incident anisotropic trapped protons are found to be lower, or equal to, those of omnidirectional models. The anisotropy induced by the asymmetric shielding distribution of Columbus/ISS is also studied. GCR proton dose rates are presented, and it is demonstrated that the presence of thick shielding may increase the dose rate. A possible problem using Geant4 for future studies of effects induced by high-energy GCR ions is discussed. The dose rate due to cosmic ray albedo neutrons is demonstrated to be negligible.</p><p>The calculated trapped proton dose rates are 120 μGy/d and 79 μGy/d for solar minimum and maximum conditions, respectively. GCR dose rates are estimated based on calculated GCR proton dose rates to 161 μGy/d and 114 μGy/d, respectively. These dose rates are found to be compatible with experimental measurements.</p>

<p>Ground-based and in-situ observations of the aurora demonstrate an extreme richness in fine structure, with spatial scales down to tens of metres and time variations occurring on a fraction of a second. To further our understanding of the aurora, it is esssential to understand the mechanisms responsible for the small-scale structuring, since this is an intrinsic property of the auroral plasma. Still many questions about dynamics and structuring of aurora on small scales remain unanswered. In this thesis the low-light optical instrument ASK (Auroral Structure and Kinetics) is used to image small-scale structures in the aurora at very high spatial and temporal resolution. ASK is a multi-spectral instrument, imaging the aurora in three selected emission lines simultaneously. This provides information on the energy of the precipitating electrons. The SIF (Spectrographic Imaging Facility) instrument has been used in conjunction with ASK, to give a more complete picture of the spectral characteristics of the aurora, and to determine the contamination of the emission lines by other emissions. Data from ASK and SIF is used to study the relation between the morphology and dynamics of small-scale structures in the aurora and the energy of the precipitating electrons. By comparing electron density profiles provided by EISCAT (European Incoherent SCATter) measurements with modeling results, information on characteristic energy and energy flux of the precipitating electrons can be obtained. One of the ASK channels is imaging a metastable O+ emission, which has a lifetime of 5 s. By tracing the afterglow in this channel optically a direct measure of the E × B drift and thus of the local ionospheric electric fields is provided.</p>

The words of Octavio Paz, from his Drift of Shadows, poetically describe the cycle of water in nature involving the erosion and weathering of stone by the force of water, further enhanced by the force of wind. This succession of events in nature is one of inter-dependency. It is also one of temporality: one element of nature perpetually affecting another, a temporality engaging elements either by impeding or by propelling. The landscape embraces, as created or destroyed by these natural forces. So, too, does architecture. As a natural force,flooding intrudes upon the landscape endangers architecture by filling the low-lying space with water, thus altering architecture and the perception of that space, both quantitatively and qualitatively. Erosion is an offspring of moving water that occurs more subtly, more gradually, over a long period of time and alters the landscape by way of addition and subtraction. As water immerses the land, it [the water] moves and moves sediment with it. Whole some land is sheared of its topsoil and stones are smoothed of their roughness (subtraction), other land is deposited with the richness of the sediment through the force of the water that carried it (addition). The photograph (Figure 1) of Ciudad Encantada (the Enchanted City) near Madrid, Spain, evokes a strong imagery of the consequence of the subtractive quality of erosion. One imagines that these boldly-cantilevered structures were once stoic with their uniform connection to the earth and connected to each other, forming ground at a higher plane. Water, however, was relentless over time and eroded the sandstone into a cavernous garden of stone pillars. Time and weather, as conjoined elements of nature, act upon the material of architecture with an inevitable and implacable force. Time and Man are the architects in partnership with nature. Architecture, therefore has an obligation, to not only its place, but also to respect these elements as co-designers. An architecture can be created that is both responsive and proactive to the dimension of time and the dynamic of nature over time.

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 131-135). Available also in a digital version from Dissertation Abstracts.

Thesis (M.A.)--York University, 1999. Graduate Programme in Psychology. / Typescript. Includes bibliographical references (leaves 97-104). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ56179.

Thesis (M.S. in Astronautical Engineering)--Naval Postgraduate School, December 2009. / Thesis Advisor(s): Kim, Jae Jim ; Agrawal, Brij N. "December 2009." Description based on title screen as viewed on January 26, 2010. Author(s) subject terms: Star tracker, Planar triangles, Angle method, Spherical triangle, Quaternion estimator, Least-squares (QUEST), TRIAD Includes bibliographical references (p. 87-88). Also available in print.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 66-71).

Thesis (M.S.)--Naval Postgraduate School, 2002. / Thesis advisor(s): Oscar Biblarz, Jose Sinibaldi. Includes bibliographical references (p. 67-69). Also available online.

Inaug.-diss.--Halle. / Lebenslauf. "Literaturverzeichnis": p. [238]-243.

Thesis (M.S.)--Florida State University, 2004. / Advisor: Dr. Frank A. Gross, Florida State University, College of Engineering, Dept. of Electrical and Computer Engineering. Title and description from dissertation home page (viewed June 18, 2004). Includes bibliographical references.