Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Mary E. Galvin-Donoghue, Dept. of Materials Science & Engineering. Includes bibliographical references.

Thesis (Ed.D.) -- Central Connecticut State University, 2007. / Thesis advisor: Marc Goldstein. "... in partial fulfillment of the requirements for the degree of Doctor of Education." Includes bibliographical references (leaves 76-84). Also available via the World Wide Web.

Prepared under contract no. EX-76-A-01-2295-037.

Incorrect system operation can, at worst, be life threatening or financially devastating. Software testing is a destructive process that aims to reveal software faults. Selection of good test data can be extremely difficult. To ease and assist test data selection, several test data generators have emerged that use a diverse range of approaches. Adaptive test data generators use existing test data to produce further effective test data. It has been observed that there is little empirical data on the adaptive approach. This thesis presents the Heuristically Aided Testing System (HATS), which is an adaptive test data generator that uses several heuristics. A heuristic embodies a test data generation technique. Four heuristics have been developed. The first heuristic, Direct Assignment, generates test data for conditions involving an input variable and a constant. The Alternating Variable heuristic determines a promising direction to modify input variables, then takes ever increasing steps in this direction. The Linear Predictor heuristic performs linear extrapolations on input variables. The final heuristic, Boundary Follower, uses input domain boundaries as a guide to locate hard-to-find solutions. Several Ada procedures have been tested with HATS; a quadratic equation solver, a triangle classifier, a remainder calculator and a linear search. Collectively they present some common and rare test data generation problems. The weakest testing criterion HATS has attempted to satisfy is all branches. Stronger, mutation-based criteria have been used on two of the procedures. HATS has achieved complete branch coverage on each procedure, except where there is a higher level of control flow complexity combined with non-linear input variables. Both branch and mutation testing criteria have enabled a better understanding of the test data generation problems and contributed to the evolution of heuristics and the development of new heuristics. This thesis contributes the following to knowledge: Empirical data on the adaptive heuristic approach to test data generation. How input domain boundaries can be used as guidance for a heuristic. An effective heuristic termination technique based on the heuristic's progress. A comparison of HATS with random testing. Properties of the test software that indicate when HATS will take less effort than random testing are identified.

The study of Latinos in the Midwestern United States is still a largely under researched territory. Until the early 2000s, the only major sources of information about Latinos in the Midwest came from surveys done in the early 20th century that investigated patterns of Mexican immigration and labor (Martinez 2011:3,4). With the influx of more Latin@s from multiple countries of origin, researchers have expanded their topics to include issues on assimilation, transnationalism, and identity (Saenz 2011: 33-34). However, these studies paint the immigrant population as affected by the host society without consideration for how the host society may be influenced by them (Tello Buntin 2011: 228). Another issue in the literature is that Latinos are consistently categorized by language, specifically Spanish (Saenz 2011: 36. 37). For this research, I am investigating the ways that Mexican community members talk about language and identity within the context of living in CC-town, Illinois. In general, this project explores what identities are being indexed by Mexican family members living in the town and how they index their identities through language.

Surface properties of polymers and competition adsorption of toluene and heptane on silica were studied using IR-visible sum frequency generation (SFG) vibrational spectroscopy. SFG is intrinsically surface sensitive because the second-order optical process is forbidden in media with inversion symmetry, such as bulk polymers and liquids. This nonlinear optical technique provides surface vibrational spectra under ambient conditions without the need of an ultra-high vacuum environment. Polymer surface properties, including surface relaxation temperature of poly(methyl methacrylate) (PMMA) and surface electronic states of poly[2-methoxy, 5-ethyl (2’-hexyloxy) para phenylenevinylene] (MEH-PPV), were investigated. It was found that there are significant differences between the surface and bulk properties for these polymers. For PMMA, a new surface structure relaxation was identified at 67°C, which does not match any known structure relaxation temperatures for bulk PMMA and is 40°C below the bulk glass transition temperature. For MEH-PPV, SFG electronic spectra, which were obtained by scanning the frequencies of incident visible and JR beams, indicated that the electronic states at the polymer/solid and air/polymer interfaces are red-shifted with respect to that of the bulk. Finally, SFG was employed to study the competition adsorption of toluene and heptane on silica surfaces. Experimental data showed that heptane adsorbed favorably compared to toluene. Using a Langmuir adsorption isotherm, the changes of Gibbs free energy for the adsorption processes were calculated to be —12.1 ± 1.8 (kJ/mol) for toluene and —16.5 ± 2.3 (kJ/mol) for heptane. / Science, Faculty of / Chemistry, Department of / Graduate

Domain generation algorithm (DGA) is a popular technique for evading detection used by many sophisticated malware families. Since the DGA domains are randomly generated, they tend to exhibit properties that are different from legitimate domain names. It is observed that shorter DGA domains used in emerging malware are more difficult to detect, in contrast to regular DGA domains that are unusually long. While length was considered as a contributing feature in earlier approaches, there has not been a systematic focus on how to leverage its impact on DGA domains detection accuracy. Through our study, we present a new detection model based on semantic and information theory features. The research applies concept of domain length threshold to detect DGA domains regardless of their lengths. The experimental evaluation of the proposed approach, using public datasets, yield a detection rate (DR) of 98.96% and a false positive rate (FPR) of 2.1%, when using random forests classification technique / Graduate

The purpose of this investigation is to compare high frequency to low frequency (50Hz) technologies. To accomplish this, two highly optimized candidate converters are built to champion each of the inverter classes. Both candidates are constrained to produce the same quasi-sinusoidal output waveforms in identical operating conditions. The low frequency inverter is designed with optimization of its output power quality and accurate loss characterization taken in mind. A new iron core design procedure is proposed that may predict core losses when using non-sinusoidal excitation. Experimental results indicate that it has a promising degree of accuracy. The high frequency candidate is designed using planar integration technology. A topology selection determines that a critical-conduction mode flyback is the most suitable option. Components are added the topology to allow resonant switching for reduced switching losses. Common-mode current arising from good capacitive coupling between windings in the planar coupled inductor is reduced using charge balancing technology. The novelty of the converter lies is in the fact that all passive components, barring the bulk of the input capacitance and the output capacitance, are incorporated into the single planar structure. Finally, a comparison of the inverters is made in the categories of power quality, regulation, efficiency, robustness and applicability to the application. The high frequency inverter is found to promise substantial advantages over the low frequency variety in most of these elements. / Dr. I.W. Hofsajer

>Magister Scientiae - MSc / The burial history, thermal maturity and petroleum generation history of the F-O Gas Field, Bredasdorp Basin have been studied using 3D basin and petroleum systems modelling approach. The investigated sedimentary basin for this study evolved around mid-late Jurassic to early Cretaceous times when Southern Africa rifted from South America. The F-O field is located 40 km SE of the F-A platform which supplies gas and condensate to the PetroSA ‘Gas to Liquid’ plant located in Mossel Bay. As data integration is an integral part of the applied modelling concept, 2D seismic profile and well data (i.e. logs and reports from four drilled wells) were integrated into a 3D structural model of the basin. Four source rock intervals (three from the Early Cretaceous stages namely; Hauterivian, Barremian, Aptian and one from the Late Cretaceous Turonian stage) were incorporated into the 3D model for evaluating source rock maturation and petroleum generation potential of the F-O Gas Field. Additionally, measured present-day temperature, vitrinite reflectance, source potential data, basin burial and thermal history and timing of source rock maturation, petroleum generation and expulsion were forwardly simulated using a 3D basin modelling technique. At present-day, Turonian source rock is mainly in early oil (0.55-0.7% VRo) window, while the Aptian and Barremian source rocks are in the main oil (0.7-1.0% VRo) window, and the Hauterivian source rock is mainly in the main oil (0.7-1.0% VRo) to late oil (1.0-1.3% VRo) window. In the entire four source rock intervals the northern domain of the modelled area show low transformation, indicated by low maturity values that are attributable to less overburden thickness. Petroleum generation begins in later part of Early Cretaceous, corresponding to high heat flow and rapid subsidence/ sedimentation rates. The Barremian and Aptian source rocks are the main petroleum generators, and both shows very high expulsion efficiencies. The modelling results however indicate that the younger Aptian source rock could be regarded as the best source rock out of the four modelled source rocks in the F-O field due to its quantity (i.e. highest TOC of 3%), quality (Type II with HI values of 400) and highest remaining potential. At present-day, ~1209 Mtons of hydrocarbons were cumulatively generated and peak generation occurred at ~43 Ma with over 581 Mtons generated. Finally, the results of this study can directly be applied for play to prospect risk analysis of the F-O gas field.

We investigate ionization and high harmonic generation (HHG) from the interaction of a mid infra-red laser pulse with a solid state system confined to nano-dimensions. The theory of strong field processes in solids is developed for confined quantum systems in general. Here it is applied to two-dimensional quantum wires with a driving field linearly polarised along the axis of the wires. Our findings indicate that that we are able to control the ionization and high-harmonic output by altering the width of the wire. Control of ionization leads to an increased damage threshold which has important implications for nano-engineering and realizing all solid state coherent XUV sources.