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The first step in the assembly of an overset grid system is to cut holes or to mark points that are inside a solid body and outside the domain of interest. Most existing approaches have been developed for use only with structured grids. A fast and robust approach that can be applied to structured, unstructured, or generalized grid topologies, with a minimum of user inputs, is desired. A new hole cutting process is presented that utilizes a Cartesian Binary tree representation of the geometry to provide a fast and efficient algorithm applicable to generalized grids. An algorithm has also been developed to mark the fringe points and find its donors. The effectiveness of the algorithm is demonstrated by testing it on generalized and structured grids.

Grid computing technology is used as inexpensive systems to gather and utilize computational capability. This technology enhances applications services by arranging machines and distributed resources in a single huge computational entity. A Grid is a system that has the ability to organize resources which are not under the subject of centralized domain, utilize protocols and interfaces, and supply high quality of service. The Grid should have the ability to enhance not only the systems performance and job throughput of the applications participated but also increase the utilization scale of resources by employing effective resource management methods to the huge amount of its resources. Grid mobility appears as a technology to facilitate the accomplishment of requirements for Grid jobs as well as Grid users. This idea depends on migrating or relocating jobs, data and application software among Grid nodes. However, making use of mobility technology leads to data confidentiality problems within the Grid. Data confidentiality is the protection of data from intruders’ attacks. The data confidentiality can be addressed by limiting the mobility to trusted parts of the Grid, but this solution leads to the notion of Virtual Organizations (VOs). Also as a result of mobility technology the need for a tool to organize and enforce policies while applying the mobility has been increased. To date, not enough attention has been paid to policies that deal with data movements within the Grid. Most existing Grid systems have support only limited types of policies (e.g. CPU resources). A few designs consider enforcing data policies in their architecture. Therefore, we propose a policy-managed Grid environment that addresses these issues (user-submitted policy, data policy, and multiple VOs). In this research, a new policy management tool has been introduced to solve the mobility limitation and data confidentiality especially in the case of mobile sharing and data movements within the Grid. We present a dynamic and heterogeneous policy management framework that can give a clear policy definition about the ability to move jobs, data and application software from nodes to nodes during jobs’ execution in the Grid environment. This framework supports a multi-organization environment with different domains, supports the external Grid user preferences along with enforces policies for data movements and the mobility feature within different domains. The results of our research have been evaluated using Jade simulator, which is a software framework fully implemented in Java language and allows agents to execute tasks defined according to the agent policy. The simulation results have verified that the research aims enhance the security and performance in the Grid environments. They also show enhanced control over data and services distribution and usage and present practical evidence in the form of scenario test-bed data as to the effectiveness of our architecture.

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Thesis (M.S.)--University of Tennessee, Knoxville, 2002. / Title from title page screen (viewed Sept. 6, 2002). Thesis advisor: Michael Langston. Document formatted into pages (vi, 119 pages). Vita. Includes bibliographical references (p. 43-46).

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The verification of power grids in modern integrated circuits must start early in the design process when adjustments can be most easily incorporated. We adopt an existing early verification framework. The framework is vectorless, i.e., it does not require input test patterns and does not rely on simulating the power grid subject to these patterns. In this framework, circuit uncertainty is captured via a set of current constraints that capture what may be known or specified from circuit behavior. Grid verification becomes a question of finding the worst-case grid behavior which, in turn, entails the solution of linear programs (LPs) whose size and number is proportional to the size of the grids. The thesis builds on this systematic framework for dealing with circuit uncertainty with the aim of improving efficiency and expanding the capabilities handled within. One contribution introduces an efficient method based on a sparse approximate inverse technique to greatly reduce the size of the required linear programs while ensuring a user-specified over-estimation margin on the exact solution. The application of the method is exhibited under both R and RC grid models. Another contribution first extends grid verification under RC grid models to also check for the worst-case branch currents. This would require as many LPs as there are branches. Then, it shows how to adapt the approximate inverse technique to speed up the branch current verification process. A third contribution proposes a novel approach to reduce the number of LPs in the voltage drop and branch current verification problems. This is achieved by examining dominance relations among node voltage drops and among branch currents. This allows us to replace a group of LPs by one conservative and tight LP. A fourth contribution proposes an efficient verification technique under RLC models. The proposed approach provides tight conservative bounds on the maximum and minimum worst-case voltage drops at every node on the grid.