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A description of several experiments carried out to investigate the behaviour of 3.2 cm. microwaves on passing through a dielectric prism is given in this thesis. Chapter I contains a description of the experimental apparatus used to generate electromagnetic radiation and to measure the field intensity in a plane perpendicular to the refracting edge of the prism. Particular emphasis is placed on a description of the receiver amplifier, and on the construction of the wax prism. In Chapter II are given the results of several preliminary investigations of the field close to, and polarized parallel to the retracting edge of the prism. Fresnel interference fringes were observed with the prism oriented as a biprism. Diffraction fringes of a 45˚ wedge, both dielectric and metallic, were observed incidentally. Evidence of the evanescent wave predicted for total internal reflection was obtained directly in this experiment where earlier evidence of such waves in the optical and microwave regions has been indirect. / Thesis / Master of Science (MSc)

The purpose of this investigation was to gain insights into the process of guiding reflection during an early field experience. Four preservice teachers' (PTs') reflection on teaching was guided by the Reflective Framework for Teaching in Physical Education (RFTPE) (Tsangaridou & O'Sullivan, 1994). Other reflective assignments included a reflective journal, video analysis, and peer observation/reflection. Data collection techniques included open-ended interviewing, reflective journals, videotape analysis, and field notes. In contrast to previous Physical Education Teacher Education (PETE) research, the findings indicated PTs were able to focus on multiple aspects of teaching: technical, situational, and sensitizing. All four PTs demonstrated the ability to consistently describe, justify, and critique meaningful events that occurred in the teaching/learning environment. Furthermore, the PTs' views on the value of guided reflection by the RFTPE (Tsangaridou & O'Sullivan, 1994) and the reflective assignments suggest that they perceived the early field experience as meaningful for their professional growth and development as prospective physical education teachers. / Ph. D.

Over 700 km of industry seismic reflection data in the central Appalachians were reprocessed using both conventional and newly developed processing schemes. A new processing sequence, called dip projection, is introduced. The technique projects crooked-line processed CMPs onto a straight line oriented in the general dip direction for the area. The new stacked sections more closely approximate a dip line and hence are more migration-friendly and interpretable than the crooked-line stacks. Methods of determining the lateral continuity of subsurface density contrasts were also applied to gravity data from the study area. Known collectively as potential field attributes, the analytic signal, the tilt angle, and the gradient of the tilt angle (the potential field wavenumber ) proved valuable in the analysis of the gravity data. Comparison of reflection seismic data from the southern and central Appalachians revealed a dichotomy of seismic reflectivity from east to west. A highly reflective crust beneath the Piedmont in both the central and southern Appalachians contrasts with a general lack of reflectivity beneath the Blue Ridge and Valley and Ridge provinces where coherent reflections are restricted to the upper 3-4 seconds of the data. This difference in reflectivity is interpreted as a fundamental difference in the location and orientation of preexisting zones of weakness between the different crustal regions with respect to the tectonic events affecting the Appalachians since the early Paleozoic. The combination of the results of new methods of seismic and potential fields processing with deep well and geologic information allowed the lateral continuity of two major structures in the central Appalachians to be examined. The Blue Ridge in Virginia was found to overly a duplex of Cambrian-Ordovician carbonates formed in response to stresses during the Alleghanian Orogeny. A large thrust sheet of similar carbonate rocks was interpreted beneath the Nittany Anticlinorium in West Virginia. To the south in Virginia, this thrust sheet is replaced by imbrication of the carbonate package. The change in structural style may be related to the existence of a lateral ramp or it may reflect the overall change in structural style from the central to southern Appalachians. / Ph. D.

In addition to being useful for some nondestructive evaluation techniques, interactions between magnetic fields and defects in solids may also alter material properties. To explore this possibility, Maxwell's equations were coupled with a continuum mechanics model for elastic strain to formulate analytical expressions for the interaction of a magnetic field with several crack geometries. The influence of crack velocity and a realistic (nonlinear) magnetic susceptibility were included into a model of this type for the first time and shown to introduce unexpected trends in the magneto-elastic stress intensity. Singularities magneto-elastic stresses appear at different combinations of magnetic field strength and crack velocity, and the stresses at the crack tip switch sign. In a related study, the interaction of an alternating magnetic field with elastic stress through was explored through a coupling effect known as magneto-acoustic resonance. A model for the phenomena, in which magnetic waves excite elastic waves and vice versa, was formulated and used to explore the spin (magnon) and anti-plane elastic (phonon) interactions in piecewise homogeneous ferromagnetic spaces with two different sets of properties. The model suggests some combinations of magnetic field and frequency can produce a new kind of wave to appear. These new waves, which we call Accompanying Surface Magnetoelastic (ASM) waves, are localized at the interface between the two ferromagnetic media and they accompany reflection and transmission waves. It is shown that the amplitudes of the reflected, transmitted, and ASM waves depend strongly on magnetic field strength, frequency, and the angle of the incident wave, as well as on the physical properties of ferromagnetic media. / Ph. D.

Background: Engineering students who achieve academic success during their first year may later disengage from challenging course material in their upper-level courses, due to perceived differences between their expectations and values and those of their degree programs. In the extreme, academic disengagement can lead to attrition. Purpose: The purpose of this study is to better understand the learning approaches and strategies used by first-year engineering students. Research questions were as follows:  How do first-year engineering students describe their learning approaches and strategies?  How do first-year engineering students customize their learning strategies among their courses?  How do first-year engineering students employ reflection as part of their learning strategies? Design/Method: I employed both qualitative and quantitative methods to collect and analyze data, using an explanatory design approach consisting of two surveys and a set of semi-structured interviews between survey administrations. The interview data from a purposive sample of survey participants were coded using a priori, pattern and comparative coding. The survey data were analyzed for medians and interquartile ranges in order to identify trends in reflective learning strategies among courses. Results: One notable finding was the fact that many interviewees stated that their overall purpose for studying was to achieve high grades by preparing for tests (a surface-level approach), and yet the learning strategies that they used reflected a deeper engagement with their course material than one would expect from students whose singular focus was on grades. Certain strategies were similar for both technical and non-technical courses, while others were dissimilar. There are also ways to combine the surface and deep learning strategies sequentially. They need not be mutually exclusive. Conclusions: The results of this study will provide educators with a starting point for the development of guided practice in meaningful learning strategies to encourage a greater engagement with learning. Both educators and administrators should be amenable to measures that would improve their students' chances for success, by providing guidance in how to learn as well as what to learn. Several recommendations are given for future studies, such as the relationships among reflection, metacognition, and critical thinking, and the integration of meaningful learning strategies into technically overloaded engineering degree curricula. / Doctor of Philosophy / I chose to study the learning approaches and strategies of first-year engineering students. The term "learning strategies" refers to study habits, but learning strategies also involve choices about how to study based on goals, motivation, and available resources. My results will provide professors and instructors with insights that they can use to help their students learn more effectively and find deeper meaning in their course material, by guiding them in how to learn as well as what to learn. Knowing how to learn is a lifelong skill. First-year engineering students have a special need to know how to learn in order to be better prepared for a more challenging workload in their upper level engineering courses. Prior studies have shown that students most often leave an engineering program during their first or second year due to inadequate academic preparation in prior years. If we are to help engineering these students to improve their learning approaches and strategies, we first need to know what approaches and strategies they currently use. My data came from two surveys that were given at the end of each of two introductory engineering courses to a group of approximately 1,200 students, and from interviews with fifteen students who had also completed the surveys. I was trying to learn more about how these students customized their learning strategies among their courses, and how they used reflection to discover the meaning behind what they are learning. One of the most interesting findings was the fact that many interviewees stated that their overall purpose for studying was to achieve high grades by preparing for tests (a surface-level approach), and yet the learning strategies that they used reflected a deeper engagement with their course material than one would expect from students whose only focus was on grades. This combination of different learning approaches was more common in engineering, science and mathematics courses than in humanities or social science courses. This dissertation also contains a three-part class assignment, given at the beginning, middle, and end of a first-year engineering course, in which students reflect on their progress in learning one or more skills that they had identified at the beginning of the course. Implications arising from my study are directed at researchers, administrators, faculty, and students, respectively, as well as opportunities for further work in this aspect of higher education. Opportunities for further studies include the relationship between reflection and critical thinking, and methods for incorporating guided practice in learning strategies into engineering degree programs that currently contain too much technical content.

Today, almost 305,000 U.S. college students are taking advantage of study abroad opportunities throughout the world. While study abroad experiences have has been increasing in number and scope, there continue to be questions about the importance and value of study abroad on the students' growth and development. This study highlights a summer study abroad program at Virginia Tech from 2008 – 2012. Reflection and transformative learning serve as the primary theoretical frameworks for this study. The work of Dewey (1933), Mezirow (1991, 1997), Moon (2004), Whitney and Clayton (2011) and others help to provide additional insight into better understanding reflection and transformative learning. The methodological framework is a qualitative case study focusing on the student participants from summer 2012 and examines the role of reflection in the academic components of the program and whether or not reflection helped to further enhance the influence and impact of the experience on the students. I collected data from photo journals, weekly reflection papers and their final exam paper, all of which comprised the academic requirements for this credit-bearing course. The participants consisted of seven female identified students and four male identified students, representing the following academic disciplines: Human Development, Geography, Political Science, Journalism, Studio Art and International Studies. Through content analysis (Mayan, 2009; Merriam, 1998), I discovered the themes of self-awareness and visibility and presence. These two themes provide a deeper understanding about how the study abroad experience has a distinct influence on the students, as can be evidenced through their academic work. While the two themes help to further reinforce the importance of reflective practice, the study also reveals that reflection can be problematic as well. / Ph. D.

This is an exploration beginning with memory of growing up in and exploring a forest surrounding my childhood home. This environment encompassed overwhelming scale and comforting intimacy, with a small intervention that related them. My thesis attempts to extract memory from growing up in the woods and create mediating, complimentary built interventions in a hypothetical world of meaning. It is an exercise in creating for others by extracting from personal memory and identifying personal sensibilities. With abstract spatial drawings, architecture's possible influence is understood at a slower pace. Through layered colored pencil drawings, my work attempts to depict human influence and its enhancement on the natural world surrounding it. / Master of Architecture

This study is a geophysical investigation that uses reflection seismic and potential field data to contribute to the development of a structural model of the North American Atlantic Passive Margin beneath the Atlantic Coastal Plain of northeastern Virginia. Specifically, this study focuses between 37.5° and 38.5° north latitude and 75.5° and 77.5° west longitude. The geophysical data include two seismic lines that were reprocessed at the Regional Geophysics Laboratory at Virginia Polytechnic Institute and State University. In addition, gravity modelling is performed in order to test the model developed from the seismic data. Several important results have been achieved from this study. Lower Cretaceous fluvial sediments are less reflective than the overlying marine sequence. This observation is most obvious toward the east, particularly on line CF-1. Reverse faulting, which might be related to movement within the basement, is observed in at least one location on line NAB-11A, near Loretto, VA. Curiously, the dip is in the opposite direction of other reverse faults observed within the coastal plain. The thickness of Triassic strata in the Taylorsville basin is constrained by seismic reflection data and gravity modelling. Results indicate that the basin is approximately 3 km deep. The strata within the basin appear to be poorly reflective except where they locally onlap the bottom of the basin, which is marked by a prominent reflector that is interpreted to be a diabase sill associated with Jurassic magmatism. In addition, the basin appears to be intruded by moderately dipping dikes that were fed by the sill. The occurrence of basaltic material within the basin is confirmed by well log data. Probably the most important result of this study is the tectonic implications of prominent, arcuate potential field anomalies and their relationships to changes in midcrustal reflectivity observed on the east side of line NAB-11A. Gravity modelling confirms the likelihood of a nearvertical, anomalous, mafic mass that extends to the Moho. This observation is supported by the loss of contiguous reflections in this area. A similar observation was made along the southern extension of the same anomaly by Coruh and others (1988) who proposed that this feature is a dike swarm associated with Mesozoic rifting. It is proposed here that this body also could be an ancient Mesozoic magma chamber that collapsed during cooling after the Atlantic margin passed into the drift sequence. / Master of Science

Virtual source gathers were generated using the principles of seismic interferometry from 135 hours of ambient noise recorded during a controlled-source survey across the Salton Sea Geothermal Field in southern California. The non-uniform nature of the noise sources violated a primary assumption of the method and generated artifacts in the data. The artifacts generated by the high-energy impulsive sources (e.g. earthquakes, shots) were removable using traditional methods of amplitude normalization prior to cross-correlation. The continuous source artifacts generated by the geothermal wells and highways required an unconventional approach of utilizing only normalized impulsive sources to successfully reduce the artifacts. Virtual source gathers were produced successfully that contained strong surface waves at 0.4-2.5 Hz, an order of magnitude below the corner frequency of the geophones, and modest body waves at 22-30 Hz, which are generally more difficult to obtain due to the need for many large, well-distributed subsurface sources. The virtual source gathers compare well to nearby explosive shots and are more densely spaced, but have a much lower signal-to-noise ratio. Analysis of the surface waves was complicated by strong higher-order modes. Spectral analysis of virtual source gathers required utilization of the geothermal plant energy, which produced usable signal at offsets required for mode separation. The virtual source dispersion curve compared well to a dispersion curve from a nearby explosive shot. P-waves were observed on the virtual source gathers. Creation of a low-quality multichannel reflection stack revealed two weak reflectors in the upper 2 km. / Master of Science