A. James Clark School of Engineering

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The collections in this community comprise faculty research works, as well as graduate theses and dissertations.

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Subject: search.filters.subject.system modeling

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    High-Performance DRAMs in Workstation Environments
    (2001-10) Cuppu, Vinodh; Jacob, Bruce; Davis, Brian; Mudge, Trevor
    This paper presents a simulation-based performance study of several of the new high-performance DRAM architectures, each evaluated in a small system organization. These small-system organizations correspond to workstation-class computers and use only a handful of DRAM chips (~10, as opposed to ~1 or ~100). The study covers Fast Page Mode, Extended Data Out, Synchronous, Enhanced Synchronous, Double Data Rate, Synchronous Link, Rambus, and Direct Rambus designs. Our simulations reveal several things: (a) current advanced DRAM technologies are attacking the memory bandwidth problem but not the latency problem; (b) bus transmission speed will soon become a primary factor limiting memory-system performance; (c) the post-L2 address stream still contains significant locality, though it varies from application to application; (d) systems without L2 caches are feasible for low- and medium-speed CPUs (1GHz and below); and (e) as we move to wider buses, row access time becomes more prominent, making it important to investigate techniques to exploit the available locality to decrease access time.
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    System Modeling and Controller Design for a Single Degree of Freedom Spacecraft Simulator
    (2005-05-03) Vess, Melissa Elaine Fleck; Sanner, Robert M; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Control systems theory is an important field of study for many branches of engineering. Teaching control systems to engineering students, however, is often difficult due to the abstract nature of the subject. TableSat is a single degree of freedom spacecraft simulator that includes sensors, actuators, a power system, and a flight processor. Students can use TableSat to design and test controllers, allowing them to see how theoretically designed controllers function in a real system. TableSat, like all real systems, is highly nonlinear. To make TableSat an effective teaching tool, the system nonlinearities are identified and compensation methods undertaken to eliminate those nonlinearities. Linear and truth system models are created for use in controller design and testing. The system models are tested and verified and then used to design and test several controllers and estimators. Results are presented that compare results for the linear model, truth model, and real TableSat system.