Thesis (M. Phil.)--University of Hong Kong, 2007. / Also available online.

Over the last decade, wind penetration in the Pacific Northwest has increased rapidly. The variable nature of this massive new resource has increased stress on the hydropower resource to the point where system limits are currently being reached. In order to cultivate continued growth of the wind energy industry both in the Pacific Northwest and the rest of the world, something must be added to help mitigate the effects of the variability of wind power. This research aims to show what can be done by adding energy storage to a wind farm. A novel model predictive control structure has been created with the focus of increasing the dispatchability and reliability of wind farm power output along with allowing participation in frequency regulation. First, the effectiveness of the addition of energy storage with simple control is explored. This is followed by a study on the performance of the system when predictive control is added. Finally, a cost analysis is performed to assess the level of savings and potential profitability of the simulated system. Conclusions support the use of an energy storage resource for more reliable wind farm performance. However, storage technologies are still approaching the price point needed to ensure profitability. / Graduation date: 2012

Richard A. Flower. / Originally presented as the author's thesis, (Ph.D.). M.I.T. Dept. of Electrical Engineering, 1974. / Bibliography: p. 66.

Modern storage systems are complex. Simple direct-attached storage devices are giving way to storage systems that are flexible, network-attached, consolidated and virtualized. Today, storage systems have their own administrators, who use specialized tools and expertise to configure and manage storage resources. As a result, database administrators are no longer in direct control of the design and configuration of their database systems' underlying storage resources. This introduces problems because database physical design and storage configuration are closely related tasks, and the separation makes it more difficult to achieve a good end-to-end design. For instance, the performance of a database system depends strongly on the storage layout of database objects, such as tables and indexes, and the separation makes it hard to design a storage layout that is tuned to the I/O workload generated by the database system. In this thesis we address this problem and attempt to close the information gap between database and storage tiers by addressing the problem of predicting the storage (I/O) workload that will be generated by a database management system. Specifically, we show how to translate a database workload description, together with a database physical design, into a characterization of the I/O workload that will result. Such a characterization can directly be used by a storage configuration tool and thus enables effective end-to-end design and configuration spanning both the database and storage tiers. We then introduce our storage layout optimization tool, which leverages such workload characterizations to generate an optimized layout for a given set of database objects. We formulate the layout problem as a non-linear programming (NLP) problem and use the I/O characterization as input to an NLP solver. We have incorporated our I/O estimation technique into the PostgreSQL database management system and our layout optimization technique into a database layout advisor. We present an empirical assessment of the cost of both tools as well as the efficacy and accuracy of their results.

As computers become pervasive in environments that include the home and community, new applications are emerging that will create and manipulate sensitive and private information. These applications span systems ranging from personal to mobile and hand held devices. They would benefit from a data storage service that protects the integrity and confidentiality of the stored data and is highly available. Such a data repository would have to meet the needs of a variety of applications, handling data with varying security and performance requirements. Providing simultaneously both high levels of security and high levels of performance may not be possible when many nodes in the system are under attack. The agility approach to building secure distributed services advocates the principle that the overhead of providing strong security guarantees should be incurred only by those applications that require such high levels of security and only at times when it is necessary to defend against high threat levels. A storage service that is designed for a variety of applications must follow the principles of agility, offering applications a range of options to choose from for their security and performance requirements. This research presents secure store, a secure and highly available distributed store to meet the performance and security needs of a variety of applications. Secure store is designed to guarantee integrity, confidentiality and availability of stored data even in the face of limited number of compromised servers. Secure store is designed based on the principles of agility. Secure store integrates two well known techniques, namely replication and secret-sharing, and exploits the tradeoffs that exist between security and performance to offer applications a range of options to choose from to suit their needs. This thesis makes several contributions, including (1) illustration of the the principles of agility, (2) a novel gossip-style secure dissemination protocol whose performance is comparable to the best-possible benign-case protocol in the absence of any malicious activity, (3) demonstration of the performance benefits of using weaker consistency models for data access, and (4) a technique called collective endorsement that can be used in other secure distributed applications.

The primary goal of this research concerns the synthesis of organic ligands in an effort to create metal-organic porous materials for the storage of gas molecules for alternative energy applications as well as other applications such as catalysis, molecular sensing, selective gas adsorption and separation. Initially, the focus of this work was on the synthesis of metal-organic polyhedra, yet the research has to date not progressed past the synthesis of ligands and the theoretical polyhedron that may form. Further efforts to obtain polyhedra from these ligands need to be explored. Concurrently, the search for a metal-organic framework that hopefully breaks the record for methane adsorption at low pressure and standard temperature was undertaken. A framework, PCN-80, was synthesized based off a newly synthesized extended bianthracene derivative, yet was unstable to the atmosphere. Hydrogen and methane adsorption capacities have been evaluated by molecular simulations; these adsorption isotherms indicated a gravimetric hydrogen uptake of 9.59 weight percent and a volumetric uptake of methane of 78.47 g/L. Following the synthesis of PCN-80, a comparison study involving the effect of the stepwise growth of the number of aromatic rings in the ligand of a MOF was pursued; the number of aromatic rings in the ligand was varied from one to eight while still maintaining a linear, ditopic moiety. The synthesis of another bianthracene-based ligand was used to complete the series of ligands and PCN-81, a two-dimensional framework with no noticeable porosity as evident by the simulated hydrogen uptake of 0.68 weight percent, was synthesized. All of these MOFs were synthesized from zinc salts to reduce the number of variables. No clear relationship was established in terms of the number of aromatic rings present in the ligand and the hydrogen adsorption capacity. However, it was confirmed that the density and hydrogen uptake in weight percent are inversely proportional. Further work needs to be done to determine what advantages are offered by these novel frameworks containing extended bianthracene derivatives. For example, with the highly fluorescent nature of the ligands from which they are composed, both PCN-80 and PCN-81 should be studied for the potential use in the application of fluorescent materials.

Thesis (M. Arch.)--University of Hong Kong, 2002. / Includes bibliographical references.

Thesis (M.S.W.)--University of Hong Kong, 1980. / Typescript.

Thesis (M. Sc.)--University of Hong Kong, 1978.

Thesis (M.B.A.)--University of Hong Kong, 1979.