Thesis (Ph. D.) in Spatial Information Science and Engineering--University of Maine, 2003. / Includes vita. Includes bibliographical references (leaves 137-143).

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph. D.)--College of Computing, Georgia Institute of Technology, 2004. Directed by Ken MacKenzie. / Vita. Includes bibliographical references (leaves 135-146).

There is a strong desire to develop new, advanced materials that can overcome the scaling difficulties present in current memory devices. Organic materials are promising candidates for resistive switching memory devices due to their low-cost advantage, simplified manufacturing process, compatibility with flexible electronic devices, and ease of being constructed cross-point cell array architecture. The operation of these types of devices requires change of device resistance when subjected to an electrical bias. We study three different systems that can achieve this requirement, wherein one is believed to be related to the charge storage in metallic trapping site, inducing space-charge field, inhibiting the charge injection; another exhibits negative differential resistance (NDR) characteristics; and the electrical transition of the third one is believed to be attributed to the formation of filaments. / text

Technologies considered for separating CO₂ from flue gas and injecting CO₂ into saline aquifers are energy intensive, costly, and technically challenging. Production of dissolved natural gas and geothermal energy by extraction of aquifer brine has shown the potential of offsetting the cost of CO₂ capture and storage along with other technical and environmental advantages. The key is to recognize inherent value in the energy content of brine in many parts of the world. Dissolved methane in brine and geothermal energy are two of the sources of energy of many aquifers. For example, geopressured-geothermal aquifers of the US Gulf Coast contain sheer volume of hot brine and dissolved methane. For the same reason, the capacity of these geopressured-geothermal aquifers for storage of CO₂ is remarkable. In this study, various reservoir models were developed from data of Texas and Louisiana Gulf Coast saline aquifers. A systematic study was performed to determine the range of uncertainty of the properties and the prospective of energy production from saline aquifers. Two CO₂ injection strategies were proposed for storage of CO₂ based on the results of simulation studies. Injection of CO₂-saturated brine showed several advantages compared to injection of supercritical CO₂. An overall energy analysis was performed on the closed-loop cycles of capture from power plants, storage of CO₂, and production of energy. The level of cost offset of CCS technology by producing energy from target aquifers strongly depends on the applications of the produced energy. The temperature of the produced brine from geopressured-geothermal aquifers is higher than the temperature of amine stripper column. Calculations for the strategy of injecting CO₂-saturated brine show that the amount of extracted thermal energy from geopressured-geothermal aquifers exceeds the amount of heat required for capturing CO₂ by amine scrubbing. In the process of injecting dissolved CO₂, compressors and pumps should run to pressurize the CO₂ and brine to be transported and achieve the required wellhead pressure. The preliminary estimations indicate that the produced methane provides more energy than that required for pressurization. In the regions where the temperature gradient is normal, the temperature of the produced brine may not be high enough for using in the chemical absorption processes. Separation mechanisms driven by pressure difference are the alternatives for chemical absorption processes since the produced methane can be burned for running the compressors and pumps. Membrane process seems to be the leading technology candidate. The preliminary estimations show that the produced power by extracted methane and geothermal energy exceeds the power needed for membranes, compressors, and pumps. Neither storage of greenhouse gases in saline aquifers nor production of methane and/or geothermal energy from these aquifers are profitable. However, designing a closed looped system by combining methods of capture, storage and production may pay off the whole process at least from the energy point of view. / text

The desired lifetime for CO₂ injection for sequestration is several decades at a high injection rate (up to 10 bbl/min or 2,400 tons/day per injector). Government regulations and geomechanical design constraints may impose a limit on the injection rate such that, for example, the bottomhole pressure remains less than 90% of the hydraulic fracture pressure. Despite injecting below the critical fracture pressure, fractures can nevertheless initiate and propagate due to a thermoelastic stress reduction caused by cool CO₂ encountering hot reservoir rock. Here we develop a numerical model to calculate whether mechanical and thermal equilibrium between the injected CO₂ and the reservoir evolves, such that fracture growth ceases. When such a condition exists, the model predicts the corresponding fracture geometry and time to reach that state. The critical pressure for fracture propagation depends on the thermoelastic stress, a function of rock properties and the temperature difference between the injected fluid and the reservoir (ΔT). Fractures will propagate as long as the thermoelastic stress and the fluid pressure at the fracture tip exceed a threshold; we calculate the extent of a fracture such that the tip pressure falls below the thermoelastically modified fracture propagation pressure. Fracture growth is strongly dependent upon the formation permeability, the level of injection pressure above fracture propagation pressure, and ΔT. / text

Not available / text

Context: Backup and Disaster Recovery, DR play a vital role in day-to-day IT operations. They define extensive aspects of business continuity plan in an enterprise. There is a continuous need to improve backup and recovery performance concerning attributes such as backup window size, high availability, security, etc. Definitive information is what enterprises strive for and rely upon to deviate from traditional methods towards advancing technologies, which are an intrinsic segment of business mundane actions. Objectives: In this study, we investigate Backup and DR plans on an enterprise level. They are compared in terms of performance metrics such as Recovery Time Objective, Recovery Point Objective, Time taken to backup, Time taken to recover and Total cost of ownership. Also, how CPU and memory utilization conduct differ in both tape-based, cloud-based Backup and DR. Methods: Literature study was the first step to formulate research questions by understanding present technologies in Backup and DR. This led us to conduct a survey for further understanding of challenges faced in industries gaining a more practical exposure. A case study was conducted in an enterprise to capture accurate values. An experiment had been deployed to compare performance of both scenarios and analyze which methodology elevates Backup and DR performance by overcoming challenges. Results: The results attained through this thesis encompass performance related metrics and also the load in terms of CPU and memory utilizations. Survey results were observed to gain better understanding of current technologies and challenges with Backup and DR in enterprises. The cloudbased backup has proved to be better in considered enterprise environment during experimentation in terms of RPO, RTO, CPU, memory utilizations and Total Cost of ownership. Conclusions: There have been numerous research works conducted on how backup and DR plans can be made better. But, they lack accurate information on how their performances vary, what all parameters can be improved by shifting towards advanced and contemporary methodologies withaddressing features such as scalability, flexibility and adaptability, which is provided in this study.

No description available.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.