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Since the advent of electronic data processing, organizations have accrued vast amounts of data contained in multiple databases with no reliable global unique identifier. These databases were developed by different departments for different purposes at different times. Organizing and analyzing these data for human services requires linking records from all sources. RL (Record Linkage) is a process that connects records that are related to the identical or a sufficiently similar entity from multiple heterogeneous databases. RL is a data and compute intensive, mission critical process. The process must be efficient enough to process big data and effective enough to provide accurate matches. We have evaluated an RL system that is currently in use by a local health and human services department. We found that they were using the typical approach that was offered by Fellegi and Sunter with tuple-by-tuple processing, using the Soundex as the primary approximate string matching method. The Soundex has been found to be unreliable both as a phonetic and as an approximate string matching method. We found that their data, in many cases, has more than one value per field, suggesting that the data were queried from a 5NF data base. Consider that if a woman has been married 3 times, she may have up to 4 last names on record. This query process produced more than one tuple per database/entity apparently generating a Cartesian product of this data. In many cases, more than a dozen tuples were observed for a single database/entity. This approach is both ineffective and inefficient. An effective RL method should handle this multi-data without redundancy and use edit-distance for approximate string matching. However, due to high computational complexity, edit-distance will not scale well with big data problems. We developed two methodologies for resolving the aforementioned issues: PSH and ALIM. PSH – The Probabilistic Signature Hash is a composite method that increases the speed of Damerau-Levenshtein edit-distance. It combines signature filtering, probabilistic hashing, length filtering and prefix pruning to increase the speed of edit-distance. It is also lossless because it does not lose any true positive matches. ALIM – Aggregate Link and Iterative Match is a graph-based record linkage methodology that uses a multi-graph to store demographic data about people. ALIM performs string matching as records are inserted into the graph. ALIM eliminates data redundancy and stores the relationships between data. We tested PSH for string comparison and found it to be approximately 6,000 times faster than DL. We tested it against the trie-join methods and found that they are up to 6.26 times faster but lose between 10 and 20 percent of true positives. We tested ALIM against a method currently in use by a local health and human services department and found ALIM to produce significantly more matches (even with more restrictive match criteria) and that ALIM ran more than twice as fast. ALIM handles the multi-data problem and PSH allows the use of edit-distance comparison in this RL model. ALIM is more efficient and effective than a currently implemented RL system. This model can also be expanded to perform social network analysis and temporal data modeling. For human services, temporal modeling can reveal how policy changes and treatments affect clients over time and social network analysis can determine the effects of these on whole families by facilitating family linkage. / Computer and Information Science

N/A / Thesis / Master of Science (MS)

Since 2000, stripe rust, caused by the fungal pathogen (Puccinia striiformis Westend. f.sp. tritici Eriks.) has resulted in yield losses of wheat (Triticum aestivium L.) in the United States, that exceeded the combined losses of leaf rust (Puccinia triticina Eriks.) and stem rust (Puccinia gramins Pers.:Pers f. sp. Tritici Eriks. E. Henn.). The objectives of this study are to identify and map adult plant stripe rust resistance quantitative trait loci (QTL) in soft red winter (SRW) wheat that are effective against race PST-100, which is the predominant race of the pathogen in the eastern U.S. Adult plant resistance (APR) was characterized in the resistant wheat lines "USG 3555", VA00W-38, and "Coker 9553". Resistance in each of the lines was evaluated in populations derived from crosses with susceptible lines "Neuse", Pioneer Brand "26R46", and VA01W-21, respectively. On chromosomes 1AS, 4BL, and 7D of USG 3555, QTL were identified that explain on average 12.8, 73.0, and 13.6 percent of the variation for stripe rust infection type (IT), and 13.5, 72.3, and 10.5 percent of the variation for stripe rust severity. A QTL from Neuse was identified on 3A that on average explains 10.9 percent of the variation for IT and 13.0 percent of the variation for severity. On chromosomes 2AS and 4BL of VA00W-38, QTL were identified that on average explain 58.9 and 19.3 percent of the variation for stripe rust IT, and 51.9 and 12.1 percent of the variation for severity. On chromosomes 6BL and 3BL of Pioneer 26R46, QTL were identified that on average explain 8.9 and 2.1 percent of the variation for IT and 11.7 and 3.9 percent of the variation for severity. Coker 9553 possesses the QTL on 4BL that is also present in USG 3555 and VA00W-38. The SSR markers, Xgwm296, Xbarc163, and Xwmc756 were tightly linked to QTL on chromosomes 2AS, 4BL, and 6BL, respectively, and their use and development of additional diagnostic markers will facilitate the incorporation and pyramiding of stripe rust resistance QTL into SRW wheat lines via marker-assisted selection. / Ph. D.

The kinematic analysis of an articulated twin body, four-wheel, robotic vehicle is presented. Polaris, a research platform and contending robotic vehicle in the Intelligent Ground Vehicle Competition (IGVC) at Virginia Tech, was redesigned in 2006 to improve the mobility of the vehicle by incorporating an innovative four-bar linkage that connects the two bodies. The new linkage design minimizes vehicle off-tracking by allowing the rear wheels to closely track the path of the front wheels. This thesis will outline the theoretical kinematic model of the four-bar linkage as applied to a twin-bodied, differentially driven vehicle. The kinematic model is validated through computer simulation as well as experimentation on a fully operational robotic vehicle. The kinematic model presented here outlines the foundations for an autonomous, four-wheel drive, multi-body control system and opens avenues for dynamically controlling the tracking of the vehicle's rear body with an actuated linkage configuration. / Master of Science

This thesis presents a technique for the optimal synthesis of planar four-bar linkages for specified force or torque generation. Unlike most previous research in mechanism force synthesis, this thesis targets linkage applications for which the mechanical advantage is prescribed but the position function is not. The advantage of this approach is that emphasis is placed on the force-generating properties of the linkage and not the output positions of the mechanism. Closed-form synthesis of force-generating linkages based on Burmester theory has recently been developed in detail. Unfortunately, closed-form methods can only be used to solve a limited class of problems and frequently require substantial intuition on the part of the designer in adjusting the input parameter specifications. The approach presented here uses optimization theory to search a solution space for the mechanism that most nearly meets the designer's specification. Use of optimization allows a greater number of constraints to be applied to the synthesis such that more practical solutions can be obtained. The proposed design technique seeks to minimize an objective function that depends primarily on the force generation properties of the linkage and secondarily on the other applied constraints. As a demonstration of the theoretical method, the optimal linkage synthesis technique is applied to a specific problem, namely, the design of a linkage for a weight-loaded exercise machine. Example solutions are generated and evaluated against the design constraints and mechanical advantage requirements. The design methodology presented has been implemented into a software package which is currently being used in industry for the design of similar linkages. / Master of Science