Digital Commons Network^™

Management Of Requirements Changes In Sequence-Based Software Specifications, Lan Lin

Doctoral Dissertations

The sequence-based software specification method was developed to convert ordinary, or typical requirements and requirements statements into mathematically precise specifications, at an acceptable level of abstraction, for deterministic systems. In view of the iterative nature of modern software developing process, requirements, once defined, are not frozen; changes are integrated continuously that need to be accommodated and validated.

The need for managing changes of requirements in sequence-based specifications arises both as a consequence of practicing this method and as a general topic in software requirements engineering. In this research we have explored the theoretical consequences of three major requirements changes in …

Scheduling Tasks With Precedence Constraints On Heterogeneous Distributed Computing Systems, Zhiao Shi

Doctoral Dissertations

Efficient scheduling is essential to exploit the tremendous potential of high performance computing systems. Scheduling tasks with precedence constraints is a well studied problem and a number of heuristics have been proposed.

In this thesis, we first consider the problem of scheduling task graphs in heterogeneous distributed computing systems (HDCS) where the processors have different capabilities. A novel, list scheduling-based algorithm to deal with this particular situation is proposed. The algorithm takes into account the resource scarcity when assigning the task node weights. It incorporates the average communication cost between the scheduling node and its node when computing the Earliest …

Asymtre: Building Coalitions For Heterogeneous Multi-Robot Teams, Fang Tang

Doctoral Dissertations

This dissertation addresses the problem of synthesizing task solution strategies for a hetero- geneous robot team to accomplish multi-robot tasks by sharing sensory and computational resources. The approach I developed is called ASyMTRe, which stands for Automated Synthesis of Multi-robot Task solutions through software Reconfiguration, pronounced “Asymmetry”. When dealing with heterogeneous teams, it is challenging to determine how the capabilities of each team member can be appropriately utilized to facilitate the accomplishment of the team-level goal. The ASyMTRe approach provides a way for the robots to reason about how to solve a task depending on their individual capabilities. The fundamental …

Scalable Techniques For Fault Tolerant High Performance Computing, Zizhong Chen

Doctoral Dissertations

As the number of processors in today’s parallel systems continues to grow, the mean-time-to-failure of these systems is becoming significantly shorter than the execu- tion time of many parallel applications. It is increasingly important for large parallel applications to be able to continue to execute in spite of the failure of some components in the system. Today’s long running scientific applications typically tolerate failures by checkpoint/restart in which all process states of an application are saved into stable storage periodically. However, as the number of processors in a system increases, the amount of data that need to be saved into …

Iterative Reconstruction Of Cone-Beam Micro-Ct Data, Thomas Matthew Benson

Doctoral Dissertations

The use of x-ray computed tomography (CT) scanners has become widespread in both clinical and preclinical contexts. CT scanners can be used to noninvasively test for anatom- ical anomalies as well as to diagnose and monitor disease progression. However, the data acquired by a CT scanner must be reconstructed prior to use and interpretation. A recon- struction algorithm processes the data and outputs a three dimensional image representing the x-ray attenuation properties of the scanned object. The algorithms in most widespread use today are based on filtered backprojection (FBP) methods. These algorithms are rela- tively fast and work well on …