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This thesis focuses on the problem of underwater target tracking with consideration for realistic conditions using active sonar. This thesis addresses the following specific problems: 1) underwater detection in three dimensional (3D) space using multipath detections and an uncertain sound speed profile in heavy clutter, 2) tracking a group of divers whose motion is dependent on each other using sonar detections corrupted by unknown structured background clutter, 3) extended target tracking (ETT) with a high-resolution sonar in the presence of multipath detection and measurement origin uncertainty. Unrealistic assumptions about the environmental conditions may degrade the performance of underwater tracking algorithms. Hence, underwater target tracking with realistic conditions is addressed by integrating the environment-induced uncertainties or constraints into the trackers. First, an iterated Bayesian framework is formulated using the ray-tracing model and an extension of the Maximum Likelihood Probabilistic Data Association (ML-PDA) algorithm to make use of multipath information. With the ray-tracing model, the algorithm can handle more realistic sound speed profile (SSP) instead of using the commonly-assumed constant velocity model or isogradient SSP. Also, by using the iterated framework, we can simultaneously estimate the SSP and target state in uncertain multipath environments. Second, a new diver dynamic motion (DDM) model is integrated into the Probability Hypothesis Density (PHD) to track the dependent motion diver targets. The algorithm is implemented with Gaussian Mixtures (GM) to ensure low computational complexity. The DDM model not only includes inter-target interactions but also the environmental influences (e.g., water flow). Furthermore, a log-Gaussian Cox process (LGCP) model is seamlessly integrated into the proposed filter to distinguish the target-originated measurement and false alarms. The final topic of interest is to address the ETT problem with multipath detections and clutter, which is practically relevant but barely addressed in the literature. An improved filter, namely MP-ET-PDA, with the classical probabilistic data association (PDA) filter and random matrices (RM) is proposed. The optimal estimates can be provided by MP-ET-PDA filter by considering all possible association events. To deal with the high computational load resulting from the data association, a Variational Bayesian (VB) clustering-aided MP-ET-PDA is proposed to provide near real-time processing capability. The traditional Cramer-Rao Lower Bound (CRLB), which is the inverse of the Fisher information matrix (FIM), quantifies the best achievable accuracy of the estimates. For the estimation problems, the corresponding theoretical bounds are derived for performance evaluation under realistic underwater conditions. / Thesis / Doctor of Philosophy (PhD)

Metal organic frameworks (MOFs) are nanoporous materials composed of inorganic and organic structural building units (SBUs). Over the last several decades, interest in MOFs has grown considerably partially due to their promising capabilities for carbon capture and storage (CCS) technologies. This is mostly due to their tunable pore chemistry, high internal surface area and unique structural diversity. This thesis focuses on computational methods that were used to analyze and organize a database of hypothetical structures to facilitate MOF discovery. The work done is detailed in two main parts. In the first part of the thesis, a topologically diverse hypothetical MOF database, containing over 300,000 structures, is screened using simplified molecular-input line-entry system (SMILES) strings to identify SBUs in each structure. The structures in the database are then renamed according to the SBUs identified by the SMILES strings algorithm. The renaming of the structures allows users to have a good idea of the geometrical and topological distribution of the database. Furthermore, a quick and reliable test is developed to identify structures with incorrect bonding patterns/missing hydrogen. In the second part of the thesis, density functional theory (DFT) - derived charges are generated for each structure in the hypothetical MOF database. Using these charges, the CO₂/N₂ selectivity is calculated and compared with the selectivity values obtained from another charge generating method, split-charge equilibration (SQE), and it is determined that there is good agreement, r = 0.96, between the two methods. A machine learning model is then developed to identify relationships between geometrical features and CO₂/N₂ selectivity.

No / This article explores the need for a framework that will assist social workers to identify when religion and belief are significant in the lives and circumstances of service users and how to take sufficient account of these issues in specific pieces of practice. It outlines the Furness / Gilligan framework and suggests that such frameworks should be used as a part of any assessment, while also being potentially useful at all stages of intervention. It reports on feedback gathered by the authors from first and final MA Social Work students who were asked to pilot the framework. It analyses their responses, in the context of national and international literature. It concludes that such a framework provides the necessary structure and challenge to assist social workers in acknowledging and engaging with issues arising from religion and belief that otherwise may remain overlooked, ignored or avoided, regardless of how significant they are to service users.

Early studies in the sociological stream of new institutionalism contributed much to the study of organization, especially in illuminating organizational isomorphism that might appear in organizational fields. Yet, at the same time, they were limited in accounting for organizational differences in the design of institutions. To help explain such differences, this study introduces a conceptual framework that brings together the Selznick tradition of old institutionalism with recent studies in new institutionalism. The framework includes multiple institutional logics, organizational positions, and organizational belief systems, all of which generate particular contexts that convey varying identities and produce organizational variations in institutional design. To examine the utility of the conceptual framework, I applied it to the design of 240 masters' programs in public affairs that are members of NASPAA, APPAM, or both. I found much variation in the coverage and structure of the programs' curricula. I discovered, for example, that programs that are affiliated only with NASPAA tend to be located in political science, public administration, and public affairs units; to be ranked in the lower-tier; to have been established in 1970 or later; to have the program mission of producing public leaders; to offer MPAd degrees; and to require higher proportions of core hours to be taken in public management. In contrast, programs affiliated only with APPAM or with both NASPAA and APPAM typically are housed in public policy units, ranked in the upper-tier, were founded in 1969 or earlier, focus on generating policy analysts, offer MPP degrees, and require higher proportions of core hours in public policy. Among the implications of these findings are that public affairs education continues to be polarized into two camps, traditional public administration and public policy. The field still lacks agreement about the courses that should be taken and how they should be taught. It seems that differing interpretations of what public affairs is and how it should be taught have helped generate the variation in the design of masters' programs in public affairs. The results of the empirical analyses also demonstrate the utility of the conceptual framework for explaining institutional differences (and similarities). More importantly, the concept of identity may offer a helpful way to combine several key features in studying organizations, including micro versus macro approaches, old versus new institutionalisms, and organizational theory versus organizational behavior. Eventually, this idea promises to enrich the analysis of institutional similarities and differences. / Ph. D.

Educational equity is a strategy through which schools prioritize equitable access to learning experiences most appropriate for each student's needs. It is an attempt to reduce inequitable student outcomes by closing gaps in students' opportunities to access the teachers, learning, and resources they need. Instructional leaders are vital to how educational equity manifests in the school setting, and assistant principals serve in this capacity among many. The purpose of this study was to identify assistant principals' preparation, opportunity, and self-reported professional learning needs to serve as equity-focused instructional leaders. The researcher sought participation from a sample of assistant principals from four school divisions in Virginia. For this quantitative study, participants completed a researcher-developed survey about equity-focused instructional leadership practices adapted from an educational equity framework developed by the Virginia Department of Education and the nationally recognized BELE framework. The researcher analyzed survey responses and used descriptive statistics to report findings that answered three research questions about assistant principals' preparation, opportunity, and self-reported professional learning needs to serve as equity-focused instructional leaders. The data revealed that assistant principals are prepared and often engage in multiple equity-focused instructional leadership practices. Assistant principals would benefit from increased opportunities and additional professional learning in some areas of equity-focused instructional leadership. The researcher identified implications for the practice of assistant principals and made recommendations for future research that might provide insight for principals, division leaders, and state personnel into how to utilize and support assistant principals in this capacity. / Doctor of Education / Pursuing equity in the educational setting aims to reduce inequitable student outcomes by closing gaps in students' opportunities to access teachers, learning, and resources that address their specific needs. Assistant principals serve as instructional leaders and are vital to establishing and maintaining equity in the school setting. The purpose of this study was to identify assistant principals' preparation, opportunity, and self-reported professional learning needs to serve as equity-focused instructional leaders. The researcher sought insight into assistant principals' beliefs about their experiences as equity-focused instructional leaders, specifically in the areas of the equity-focused instructional leadership strategies outlined in a framework developed by the Virginia Department of Education and the nationally recognized BELE framework. The researcher sought to gain insight for principals, division leaders, and state personnel to support their efforts to utilize and support assistant principals in this capacity. The researcher conducted a quantitative study using a survey research design. The researcher conducted the study in Virginia and collected data from a sample of 65 assistant principals in four school divisions. The researcher analyzed responses to the survey and used descriptive statistics to report findings that answered three research questions about assistant principals' preparation, opportunity, and self-reported professional learning needs to serve as equity-focused instructional leaders. Findings indicate that assistant principals are both prepared and have opportunities to serve as equity-focused leaders. However, they would benefit from increased opportunities and professional learning to improve their practice.

Internet Protocol version 6 (IPv6) is being adopted in networks around the world as the Internet Protocol version 4 (IPv4) addressing space reaches its maximum capacity. Although there are IPv6 applications being developed, there are not many production IPv6 networks in place in which these applications can be deployed. Simulation presents a cost effective alternative to setting up a live test bed of devices to validate specific IPv6 environments before actual physical deployment. OPNET Modeler provides the capability to simulate the IPv6 protocol and System-in-the-Loop, an add-on module, allows for real communication traffic from physical devices to be converted and sent over the simulated network. This research has developed a campus framework, modeled after the Virginia Tech Blacksburg campus, to verify and validate standard and custom IPv6 applications. Specifically, the framework was used to test MT6D, a custom IPv6 security application developed in the Virginia Tech IT Security Lab (ITSL) as well as test Voice over IP (VoIP) as a somewhat bandwidth demanding benchmarking standard application. The work presented shows that simulation helped to identify potential issues within the applications and verified the results after fixes were applied. It also reveals challenges and shortcomings of OPNET Modeler's IPv6 implementation and presents potential solutions to these problems. / Master of Science