This thesis proposes the use of several supervised machine learning classification models that were built to detect the distribution of malicious content in OSNs. The main focus was on ensemble learning algorithms such as Random Forest, gradient boosting trees, extra trees, and XGBoost. Features were used to identify social network posts that contain malicious URLs derived from several sources, such as domain WHOIS record, web page content, URL lexical and redirection data, and Twitter metadata. The thesis describes a systematic analysis of the hyper-parameters of tree-based models. The impact of key parameters, such as the number of trees, depth of trees and minimum size of leaf nodes on classification performance, was assessed. The results show that controlling the complexity of Random Forest classifiers applied to social media spam is essential to avoid overfitting and optimise performance. The model complexity could be reduced by removing uninformative features, as the complexity they add to the model is greater than the advantages they give to the model to make decisions. Moreover, model-combining methods were tested, which are the voting and stacking methods. Both show advantages and disadvantages; however, in general, they appear to provide a statistically significant improvement in comparison to the highest singular model. The critical benefit of applying the stacking method to automate the model selection process is that it is effective in giving more weight to more topperforming models and less affected by weak ones. Finally, 'SuspectRate', an online malicious URL detection system, was built to offer a service to give a suspicious probability of tweets with attached URLs. A key feature of this system is that it can dynamically retrain and expand current models.

This thesis presents a newly developed evaluation model, EMISHD (An "Evaluation Model for Information Security Strategies in Healthcare Data Systems") which can address the specific requirements of information security in healthcare sector. Based on a systematic literature review and case study, the information security requirements and the existing evaluation models used to examine the information security strategies of healthcare data systems have been analysed. The requirements of information security in any sector generally vary in line with changes in laws and regulations, and the emergence of new technologies and threats, which require existing information security strategies to be strengthened to deal with new challenges. The systemic review of the existing evaluation models identified from the previous research resulted in the development of a new evaluation model (EMISHD) specifically designed to examine the information security strategies in healthcare data systems according to the specific requirements. A case study of a healthcare organisation in Saudi Arabia is conducted in order to apply the newly developed evaluation model (EMISHD) in a real life case and to validate the evaluation results through observation.

Traditional public policy decision making has been supported with a cyclical framework based on the rational model, first introduced in the 1950s by Harold Lasswell. However, public policy problems are intrinsically complex and are usually inherently multi-disciplinary and critics of the cyclical model call for more holistic approaches to public policy decision making to address this complexity. This means methodologies, tools and techniques that support multiple perspectives, involve multiple stakeholders and require multiple sources of information are essential for the investigation, analysis and support of public policy decision making. The proposed framework presented in this thesis has been developed to address the issues arising when investigating public policy problems. It addresses the complexity and multiplicity that is public policy decision making, concentrating on problem identification and definition. There is a presentation of the existing frameworks for policy decision making and their limitations. It discusses issues with problem recognition and definition and proposes a methodological framework that provides a thorough investigation into the problem domain to identify areas for policy actions, critical information needs and enables simulation and experimentation to identify unintended consequences. Traditional approaches to policy decision making have been criticised for failing to take into account the wealth of information generated and used by the policy process. This has led to the emergence of Policy Informatics as a new field of research. This thesis shows that a methodological framework for policy design and analysis can be created, based on the core concepts of Policy Informatics and Systems Thinking, that more thoroughly investigates the problem space than previous approaches and addresses common issues with problem recognition and definition that exist in more traditional policy decision making frameworks.

This thesis presents the design and implementation of a Chatbot that is able to answer questions about an entity it is learning about. This Chatbot is capable of automatically generating multiple genres using a unique technique to populate its SQL database from the Web. Our Online Feedable Chatbot can hold a conversation with the user regarding the information it has extracted from the Web. Our Online Feedable Chatbot attempts to create Question Answer pairs (QAPs) and acquire imperative sentences specially targeted at the entity it gives information about. A method to select the best response for a Chatbot query among a set of sentences using hybrid terms, syntactic, and semantic extracted features is developed as a response search system of our Online Feedable Chatbot. This tutor Chatbot can expand its training knowledge base by automatically extracting more QAPs and imperative sentences from the Web whenever the user needs to learn about a new entity and without any instructor's supervision, amendments, or control.

This thesis introduces novel integrated millimetre wave components for amplification and filtering. The conventional coupling matrix theory for passive filters is extended to the design of ‘filter-amplifiers’, which have both filtering and amplification functionalities. The design is based on the coupling matrix theory, and for this approach extra elements are added to the standard coupling matrix to represent the transistor. Based on the specification of the filter and small-signal parameters of the transistor, the active coupling matrices for the ‘filter-amplifier’ can be synthesised. Adopting the active coupling matrices, the resonators of the filter adjacent to the transistor and the coupling between them are modified mathematically to provide a Chebyshev filter response with amplification. Although the transistor has complex input and output impedances, it can be matched to the filters by choice of coupling structure and resonance frequency. This is particularly useful as the filter resonators can be of a different construction (e.g. waveguide) to the amplifier (e.g. microstrip).

Thesis (M.S.)--State University of New York at Binghamton, Electrical and Computer Engineering Dept., 2006. / Includes bibliographical references.

The microprocessors will have more than a billion logic transistors on a single chip in the near future. Several alternatives have been suggested for obtaining highest performance with billion-transistor chips. To achieve the highest performance possible, an on-chip multiprocessor will become one promising alternative to the current superscalar microprocessor. It may execute multiple threads effectively on multiple processors in parallel if the application program is parallelized properly. This increases the utilization of the processor and provides latency tolerance for the latency caused from data dependency and cache misses. The Electronics and Telecommunications Research Institute (ETRI) in South Korea developed an on-chip multiprocessor RAPTOR Simulator "RapSim", which contains four SPARC microprocessor cores in it. To support this 4-way multiprocessor simulator, Multithreaded Mini Operating System (MMOS) was developed by OSU MMOS group. RapSim runs multiple threads on multiple processor cores concurrently. POSIX threads was used to build Symmetric Multiprocessor (SMP) safe Pthreads package, called MMOS. Benchmarks should be properly parallelized by the programmer to run multiple threads across the multiple processors simultaneously. Performance simulation results shows the RAPTOR can exploit thread level parallelism effectively and offer a promising architecture for future on-chip multiprocessor designs. / Graduation date: 2000

There appears to be a broad agreement that high-performance computers of the future will be Massively Parallel Architectures (MPAs), where all processors are interconnected by a high-speed network. One of the major problems with MPAs is the latency observed for remote operations. One technique to hide this latency is multithreading. In multithreading, whenever an instruction accesses a remote location, the processor switches to the next available thread waiting for execution. There have been a number of architectures proposed to implement multithreading. One such architecture is the Threaded Abstract Machine (TAM). It supports fine-grain multithreading by an appropriate compilation strategy rather that through elaborate hardware. Experiments on TAM have already shown that fine-grain multithreading on conventional architectures can achieve reasonable performance. However, a significant deficiency of the conventional design in the context of fine-grain program execution is that the message handling is viewed as an appendix rather than as an integral, essential part of the architecture. Considering that message handling in TAM can constitute as much as one fifth to one half of total instructions executed, special effort must be given to support it in the underlying hardware. This thesis presents the design modifications required to efficiently support message handling for fine-grain parallelism on stock processors. The idea of having a separate processor is proposed and extended to reduce the overhead due to messages. A detailed hardware is designed to establish the interface between the conventional processor and the message-handling processor. At the same time, the necessary cycle cost required to guarantee atomicity between the two processors is minimized. However, the hardware modifications are kept to a minimum so as not to disturb the original functionality of a conventional RISC processor. Finally, the effectiveness of the proposed architecture is analyzed in terms of its impact on the system. The distribution of the workload between both processors is estimated to indicate the potential speed-up that can be achieved with a separate processor to handle messages. / Graduation date: 1995

Thesis (Ph. D.)--University of Washington, 1982. / Vita. Includes bibliographical references.

Many standards aimed at managing networks currently exist, and yet networks remain notoriously difficult to maintain. Template-based management systems go a long way towards solving this problem. By developing an XML based language to describe network elements, as well as the topology of a network, we can create tools that are free from vendor specific idiosyncrasies, and are capable of managing both today’s networks and those of the future.