Graduation date: 1994

Innovations in the microarchitecture and prominent advances in the semiconductor process technology enable sophisticated and powerful microprocessors. However, they also lead to increased power consumption. The main contribution of the thesis is the demonstration of Semantics-Oriented Low Power Architecture techniques that use the semantics of memory references and variables used in an application program to reduce the power consumption in the memory sub-system of a microprocessor. The Semantic-Aware Multilateral Partitioning (SAM) technique reduces the cache and TLB power consumption by decoupling the data TLB lookups and the data cache accesses, based on the semantic regions defined by the programming languages and the software convention, into discrete reference sub-streams, namely, stack, global static, and heap. To reduce the power consumed by the snoops in Chip Multiprocessor, we propose a hardware technique called Selective Snoop Probe (SSP) and a compiler-based hardware supported technique called Essential Snoop Probe (ESP) that use the properties of the program variables. By selectively sending the snoop probes, the SSP and ESP techniques relax the conservative nature of the cache coherency protocol and its implementation to reduce power and improve performance.

Computing systems are experiencing a significant evolution triggered by the convergence of multiple technologies including multicore processor architectures, expanding I/O capabilities (e.g., storage and wireless communication), and virtualization solutions. The integration of these technologies has been driven by the need to deliver performance and functionality for applications being developed in emerging mobile and enterprise systems. These accomplishments, though, have come at the cost of increased power and thermal signatures of computing platforms. In response to the resulting power issues, power centric policies have been deployed across all layers of the stack including platform hardware, operating systems, application middleware, and virtualization components. Effective active power management requires that these independent layers or components behave constructively to attain globally desirable benefits. Two choices are (1) to tightly integrate different policies using negotiated management decisions, and (2) to coordinate their use based on the localized policy decisions that are already part of modern computer architectures and software systems. Recognizing the realities of (2), the goal of this thesis is to identify, define, and evaluate novel system-level coordination mechanisms between diverse management components that exist across system layers. The end goal of these mechanisms, then, is to enable synergistic behaviors between management entities, across different levels of abstraction, and across different physical platforms to improve power management functionality. Contributions from this work include operating system level mechanisms that dynamically capture workload behavior thereby enabling power efficient scheduling, and system descriptor mechanisms that allow for improved workload allocation and resource management schemes. Finally, observing the strong need for coordination in managing virtualized systems due to the existence of multiple, independent system layers, a set of extensions to virtualization architectures for effectively coordinating VM management in datacenters are developed.

Using seawater in cooling systems is a common practice in many parts of the world where there is a shortage of freshwater. However, biofouling is one of the major operational problems associated with the usage of seawater in cooling systems. Microfouling is caused by the activities of microorganisms, such as bacteria and algae, producing a very thin layer that sticks to the inside surface of the tubes in heat exchangers. This thin layer has a tremendously negative impact on heat transferred across the heat exchanger tubes in the system. In some instances, even a 250 micrometer thickness of fouling film can reduce the heat exchanger's heat transfer coefficient by 50 percent. On the other hand, macrofouling is the blockage caused by relatively large marine organisms, such as oysters, mussels, clams, and barnacles. A biocide is typically added to eliminate, or at least reduce, biofouling. Typically, microfouling can be controlled by intermittent dosages, and macrofouling can be controlled by continuous dosages of biocide. The aim of this research work is to develop a systematic approach to the optimal operating and design alternatives for integrated seawater cooling systems in industrial facilities. A process integration framework is used to provide a holistic approach to optimizing the design and operation of the seawater cooling system, along with the dosage and discharge systems. Optimization formulations are employed to systematize the decision-making and to reconcile the various economic, technical, and environmental aspects of the problem. Building blocks of the approach include the biocide water chemistry and kinetics, process cooling requirements, dosage scenarios and dynamic profiles, biofilm growth, seawater discharge, and environmental regulations. Seawater chemistry is studied with emphasis on the usage of biocide for seawater cooling. A multi-period optimization formulation is developed and solved to determine: * The optimal levels of dosing and dechlorination chemicals * The timing of maintenance to clean the heat-exchange * The dynamic dependence of the biofilm growth on the applied doses, the seawater-biocide chemistry, the process conditions, and seawater characteristics for each time period. The technical, economic, and environmental considerations of the system are accounted for and discussed through case studies.

Thesis (Ph.D.); Submitted to Department of Chemical Engineering, Colorado School of Mines, Golden, CO (US); 1 Sep 2004. / Published through the Information Bridge: DOE Scientific and Technical Information. "LA-14178-T" R.L. Ames. 09/01/2004. Report is also available in paper and microfiche from NTIS.

Thesis (M. S.)--Building Construction, Georgia Institute of Technology, 2008. / Committee Chair: Dr. Linda Thomas-Mobley; Committee Member: Dr. Del Kiernan-Lewis; Committee Member: Professor Kathy Roper.

Thesis (PhD(Agricultural Economics, Extension and Rural Development))--University of Pretoria, 2007. / Includes bibliographical references.

Thesis (M.Arch.) - Carleton University, 2006. / Includes bibliographical references (p. 146-147). Also available in electronic format on the Internet.

Thesis (M.U.A.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 109-126). Also available via the Internet.

Thesis (Ph.D.)--Murdoch University, 2008. / Thesis submitted to the Faculty of Creative Technologies and Media. Includes bibliographical references (leaves 137-148)