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Physical Sciences and Mathematics Commons

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Computer Sciences

2002

William & Mary

Articles 1 - 6 of 6

Full-Text Articles in Physical Sciences and Mathematics

Software And Hardware Methods For Memory Access Latency Reduction On Ilp Processors, Zhao Zhang Jan 2002

Software And Hardware Methods For Memory Access Latency Reduction On Ilp Processors, Zhao Zhang

Dissertations, Theses, and Masters Projects

While microprocessors have doubled their speed every 18 months, performance improvement of memory systems has continued to lag behind. to address the speed gap between CPU and memory, a standard multi-level caching organization has been built for fast data accesses before the data have to be accessed in DRAM core. The existence of these caches in a computer system, such as L1, L2, L3, and DRAM row buffers, does not mean that data locality will be automatically exploited. The effective use of the memory hierarchy mainly depends on how data are allocated and how memory accesses are scheduled. In this …


The Fusion And Integration Of Virtual Sensors, Thomas F. Litant Jan 2002

The Fusion And Integration Of Virtual Sensors, Thomas F. Litant

Dissertations, Theses, and Masters Projects

There are numerous sensors from which to choose when designing a mobile robot: ultrasonic, infrared, radar, or laser range finders, video, collision detectors, or beacon based systems such as the Global Positioning System. In order to meet the need for reliability, accuracy, and fault tolerance, mobile robot designers often place multiple sensors on the same platform, or combine sensor data from multiple platforms. The combination of the data from multiple sensors to improve reliability, accuracy, and fault tolerance is termed Sensor Fusion.;The types of robotic sensors are as varied as the properties of the environment that need to be sensed. …


Simulation Techniques In An Artificial Society Model, Barry Glenn Lawson Jan 2002

Simulation Techniques In An Artificial Society Model, Barry Glenn Lawson

Dissertations, Theses, and Masters Projects

"Artificial society" refers to a generic class of agent-based simulation models used to discover global social structures and collective behavior produced by simple local rules and interaction mechanisms. Artificial society models are applicable in a variety of disciplines, including the modeling of chemical and biological processes, natural phenomena, and complex adaptive systems. We focus on the underlying simulation techniques used in artificial society discrete-event simulation models, including model time evolution and computational performance.;Although for some applications synchronous time evolution is the correct modeling approach, many other applications are better represented using asynchronous time evolution. We claim that asynchronous time evolution …


Simulation And Numerical Solution Of Stochastic Petri Nets With Discrete And Continuous Timing, Robert Linzey Jones Iii Jan 2002

Simulation And Numerical Solution Of Stochastic Petri Nets With Discrete And Continuous Timing, Robert Linzey Jones Iii

Dissertations, Theses, and Masters Projects

We introduce a novel stochastic Petri net formalism where discrete and continuous phase-type firing delays can appear in the same model. By capturing deterministic and generally random behavior in discrete or continuous time, as appropriate, the formalism affords higher modeling fidelity and efficiencies to use in practice. We formally specify the underlying stochastic process as a general state space Markov chain and show that it is regenerative, thus amenable to renewal theory techniques to obtain steady-state solutions. We present two steady-state analysis methods depending on the class of problem: one using exact numerical techniques, the other using simulation. Although regenerative …


Aggregate Matrix-Analytic Techniques And Their Applications, Alma Riska Jan 2002

Aggregate Matrix-Analytic Techniques And Their Applications, Alma Riska

Dissertations, Theses, and Masters Projects

The complexity of computer systems affects the complexity of modeling techniques that can be used for their performance analysis. In this dissertation, we develop a set of techniques that are based on tractable analytic models and enable efficient performance analysis of computer systems. Our approach is three pronged: first, we propose new techniques to parameterize measurement data with Markovian-based stochastic processes that can be further used as input into queueing systems; second, we propose new methods to efficiently solve complex queueing models; and third, we use the proposed methods to evaluate the performance of clustered Web servers and propose new …


Adaptive And Secured Resource Management In Distributed And Internet Systems, Li Xiao Jan 2002

Adaptive And Secured Resource Management In Distributed And Internet Systems, Li Xiao

Dissertations, Theses, and Masters Projects

The effectiveness of computer system resource management has been always determined by two major factors: (1) workload demands and management objectives, (2) the updates of the computer technology. These two factors are dynamically changing, and resource management systems must be timely adaptive to the changes. This dissertation attempts to address several important and related resource management issues.;We first study memory system utilization in centralized servers by improving memory performance of sorting algorithms, which provides fundamental understanding on memory system organizations and its performance optimizations for data-intensive workloads. to reduce different types of cache misses, we restructure the mergesort and quicksort …