Zugl.: Tübingen, Univ., Diss., 2005

Diss. phil.-hist. Bern. - (KA). / Untertitel: Andreas Gryphius: Absurda comica oder Herr Peter Squentz : Schimpfspiel. Ludwig Tieck: Der gestiefelte Kater. Luigi Pirandello: Sei personaggi in cerca d'autore.

Zugl.: Basel, Univ., Diss., 2007

Inaug.-Diss.--Königsberg i. Pr. / Lebenslauf. "Literaturverzeichnis": p. 70.

Understanding the dynamic behavior of particulate materials is extremely important to many industrial processes with a wide range of applications ranging from hopper flows in agriculture to tumbling mills in the mining industry. Thus simulating the dynamics of particulate materials is critical in the design and optimization of such processes. The mechanical behavior of particulate materials is complex and cannot be described by a closed form solution for more than a few particles. A popular and successful numerical approach in simulating the underlying dynamics of particulate materials is the discrete element method (DEM). However, the DEM is computationally expensive and computationally viable simulations are typically restricted to a few particles with realistic particle shape or a larger number of particles with an often oversimplified particle shape. It has been demonstrated for numerous applications that an accurate representation of the particle shape is essential to accurately capture the macroscopic transport of particulates. The most common approach to represent particle shape is by using a cluster of spheres to approximate the shape of a particle. This approach is computationally intensive as multiple spherical particles are required to represent a single non-spherical particle. In addition spherical particles are for certain applications a poor approximation when sharp interfaces are essential to capture the bulk transport behavior. An advantage of this approach is that non-convex particles are handled with ease. Polyhedra represent the geometry of most convex particulate materials well and when combined with appropriate contact models exhibit realistic transport behavior to that of the actual system. However detecting collisions between the polyhedra is computationally expensive, often limiting simulations to only a few thousand of particles. Driven by the demand for real-time graphics, the Graphical Processor Unit (GPU) offers cluster type performance at a fraction of the computational cost. The parallel nature of the GPU allows for a large number of simple independent processes to be executed in parallel. This results in a significant speed up over conventional implementations utilizing the Central Processing Unit (CPU) architecture, when algorithms are well aligned and optimized for the threading model of the GPU. This thesis investigates the suitability of the GPU architecture to simulate the transport of particulate materials using the DEM. The focus of this thesis is to develop a computational framework for the GPU architecture that can model (i) tens of millions of spherical particles and (ii) millions of polyhedral particles in a realistic time frame on a desktop computer using a single GPU. The contribution of this thesis is the development of a novel GPU computational frame- work Blaze-DEM, that encompasses collision detection algorithms and various heuristics that are optimized for the parallel GPU architecture. This research has resulted in a new computational performance level being reached in DEM simulations for both spherical / Thesis (PhD)--University of Pretoria, 2015. / Mechanical and Aeronautical Engineering / PhD / Unrestricted

Mass balance records of glaciers help to understand long term climate change, yet there are very few in-situ measurements of mass balance in Himalayan glaciers. Mass balance of major glaciers in the Sagarmatha National Park was assessed using Digital Elevation Model prepared from ASTER images for period 2002 & 2005 and 2002 & 2008, employing geodetic model. Overall glacial mass balance during 2002-2005 was -2.978 plus/minus 0.89 and during 2002-2008 was -0.94 plus/minus 0.34 m.w.e per annum. Glacier melt could form glacial lakes in high Himalayas. One of the glacial lakes, Imja Lake in the study area increased its surface area by 268% from 1975 to 2010. Temperature analysis from MODIS data between 2000 and 2011 indicated increase in temperature in the study area. General loss of glacial mass in the Himalayan region indicated, and these loses if continue in the future will lead to catastrophic environmental and economic impacts.

Current researchers have looked to nature to learn how self-assembly processes occur. By understanding the self-assembly process, designers can begin to build strong structural materials that are extremely light weight. The discrete element modeling method was used to gain a better understanding of the directed self-assembly of M13 bacteriophage. This model was parameterized from molecular dynamics simulations at the nanometer scale. Three types of functionalized bacteriophage were studied: Wild-type, 4E, and CLP8. Results showed that Wild-type phage are attracted in a head-to-tail orientation, but repelled in head-to-head orientation. The 4E bacteriophage behaved similarly with a stronger bond in the head-to-tail orientation, and CLP8 showed to physically repel in either orientation. The overall finding was that the electrostatic physics dominated as the controlling forces of the phage interactions.

Three-dimensional (3D) visualization is rapidly becoming an important tool for many engineering projects. Accurate digital representations of terrain and ground features are extremely useful for efficient design, communication and data representation in projects involving land development, transportation planning, hydrologic analysis, environmental impact studies, and much more. Within the scope of terrain modeling lie a wide variety of techniques used to build digital elevation models (DEMs). Each approach has inherent problems and difficulties that can alter the accuracy and usability of the DEM produced. The main objectives of this study are to examine the various methods used for the creation of digital elevation models and make recommendations as to the appropriate techniques to use depending on specific project circumstances. Data sets generated using two of the methods, photogrammetry and LIDAR, are used to build digital terrain models in various software packages for an analysis of data usability and function. The key results of this research project are two DEMs of a real-world transportation study area and a set of conclusions and recommendations that give insight into the exact methods to be used on various projects. The paper ends with two short appendices, the first of which discusses several software packages and their effectiveness in DEM creation and 3-D modeling. The final appendix is a flow chart summarizing the recommendations for the seven DEM creation methods. / Master of Science

Digital Elevation Models (DEMs) are computer-generated representations of the earth's surface. These surfaces can be used to predicted Line-of-Sight (LOS) radio propagation. DEM resolution can affect the results of this prediction. This study examines the effect of DEM resolution on accuracy by comparing varied resolution terrain data for a portion of Blacksburg, Virginia using the prediction of ESRI's ArcView® viewshed algorithm. Results show that resolutions between one-meter and thirty-meters have little effect on the aggregate accuracy of the viewshed. / Master of Science

Thesis advisor: Noah P. Snyder / Multi-temporal elevation (MTE) analysis is used to study topographic changes at specific intervals. Barrier-island complexes are often studied using this MTE analysis to quantify changes to the environment after hurricanes to understand how dynamic landscapes respond to different forcings. The Sandy Pond spit (SPS) is a north-south trending barrier island on the eastern shore of Lake Ontario, New York, which responds dynamically to fluctuations in water levels, ice cover, and storms. Prior research reconstructed the geomorphic history of the SPS from 1878-2013, determining that the most significant factor affecting decadal change is the lake-water elevation. In the summers of 2017 and 2019, anomalously high precipitation and lake levels resulted in increased erosion along the SPS, and flooding in neighboring communities. In this study I used shoreline position, foredune crest position and elevation and volume of deposition and erosion to determine the dominant force of geometric change on the SPS before, during and after the high water events in 2017 and 2019, using the study period 2001-2020. Lidar data and small uncrewed aerial system images are used to generate digital elevation models (DEMs) and DEMs of difference (DoDs) from surveys conducted in May 2001, July 2007, June 2011, October 2015, May 2018, September 2018, July 2020 and August 2020. Results indicated water level was the most significant factor altering the topography of the SPS. Large storm events although erosive, were not as destructive to the shore environment as the long duration elevated summer water levels. From 2001-2015 the shoreline advanced an average of 0.25 m/year. From 2015-2018 and 2018-2020 the shoreline retreated 0.62 m/year, and 3.27 m/year respectively. The foredune position and elevation altered due to erosion of the dune toe caused by wave action and shoreline retreat from 2015-2020 compared to 2001-2015. To study volumetric changes, the SPS was split into seven ecogeomorphic zones that characterize the barrier-spit system at large. From 2007-2015 net deposition was recorded at five of the seven zones when applying a 95% confidence interval. The zones recording erosion were characterized by high dune complexes with sparse vegetation to anchor sand. From 2015-2018 net erosion was recorded in all seven zones, indicating water level had a statistically significant effect on the rate and volume of geomorphic change to this ecosystem. / Thesis (MS) — Boston College, 2022. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Earth and Environmental Sciences.