Master of Science (MS), Ohio University, 2009, Geological Sciences (Arts and Sciences)

A method for combining resistivity and surface-wave tomography data has been developed to enhance the near-surface anomalies imaged by both techniques. Efficient acquisition of both dipole-dipole resistivity and multichannel surface-wave data can be accomplished using an automated multi-electrode resistivity meter and a 24-channel engineering seismograph with 18 active channels employed in roll along mode. A 100m survey using a 2m geophone spacing and a 4m electrode separation can be completed in approximately 6 hours. Electrical and seismic data may be combined in a number of ways to enhance various types of anomalies. For example, the division of resistivity into shear-wave velocity (from the surface-wave inversion) can be used to strengthen the contrast of the alluvium/consolidated rock contact in depth-to-bedrock studies. Similarly, since the likelihood that a resistivity anomaly represents a void is increased if it also displays low shear-wave velocity, the ratio of resistivity to shear-wave velocity will enhance anomalies due to voids and suppress those arriving from other features. In a floodplain survey in Athens, Ohio, this “combined image” enhanced anomalies common to both seismic and resistivity images and suppressed features observed in only one physical property. Thus, combined surface-wave and electrical resistivity surveys can be effective in situations where the need for increased anomaly strength and/or decreased ambiguity in interpretation are worth the additional field work and processing time.

Committee: Douglas H. Green PhD (Advisor); Gregory C. Nadon PhD (Committee Member); Dina Lopez PhD (Committee Member) Subjects: Geology; Geophysics

PHD, Kent State University, 2019, College of Arts and Sciences / Department of Physics

The main goal of this research is to study the surface properties of liquid-vapor and liquid-liquid-vapor interfaces with high precision using the technique of surface light scattering spectroscopy (SLSS), which measures the power spectrum of light scattered from thermally generated capillary waves with an rms height ~1 nm. This power spectrum depends on both surface and bulk properties of the fluid, including surface tension and bulk viscosity, allowing the inference of the values of these and perhaps other parameters. In this dissertation, I focus on the surface tension and bulk viscosity associated with a liquid. Innovative optical design has increased signal and signal-to-noise ratio. This enhances measurement accuracy over the entire range of wave numbers, while enabling measurements at higher wave numbers above 1500/cm. After refining the apparatus and technique as much as possible, I apply it to a sequence of systems. (a) Simple Fluids: Standard materials including acetone, pentane, methanol and water serve to calibrate and validate the SLSS technique and experimental protocol. (b) Highly viscous fluids, relevant for capillary-driven fluid management to control propellant transfer in space flight. We explore the regime between the overdamped and underdamped cases, which have been difficult to characterize with SLSS, using well-characterized glycerol/water mixtures. (c) Mixtures: Measurements of pentane/2-methylpentane mixtures prepare for an upcoming NASA microgravity experiment to optimize the effectiveness of wickless heat pipes. (d) Thin organic films on water: coupling between upper and lower interfaces of a thin film allows the study of Casimir-Polder forces and measurement of the onset of wave mode transitions, for example, peristaltic suppression. (e) Molecularly thin films on water: thin films of a smectic liquid crystal on water have many applications, directly as biosensors, and indirectly, to develop a better understanding of alignment laye (open full item for complete abstract)

Committee: Elizabeth Mann (Advisor) Subjects: Physics

Master of Science, The Ohio State University, 1965, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1966, Graduate School

Committee: Not Provided (Other) Subjects:

PhD, University of Cincinnati, 2004, Engineering : Aerospace Engineering

SAW velocity spectroscopy has been long considered to be one of the leading candidates for nondestructive characterization of surface-treated metals because of its ability to probe the material properties at different penetration depths depending on the inspection frequency. This research effort is directed towards the use of a highly accurate laser-ultrasonic technique to study the feasibility of SAW dispersion spectroscopy for residual stress assessment on shot-peened metals. Unfortunately, surface acoustic waves are sensitive to spurious parameters, which are byproducts of the surface treatment, i.e., surface roughness and cold work The experimental results obtained on rough surfaces were compared to both theoretical and computational simulations for surface wave induced dispersion from the literature. It was found that experimental results were consistent with the numerical simulations, but neither of them showed conclusive evidence of the high frequency positive dispersion suggested by earlier models. Also, we studied the effect of gradually relaxed shot-peened aluminum specimens on the SAW velocity. Finally, we investigated the individual contribution of residual stress by determining the acoustoelastic constants of the material and we present numerical predictions of the effect of texture on the surface wave dispersion. We detail that the dispersion of the surface wave arises from three different sources, namely, (a) there is an apparent dispersion on smooth surfaces due to the diffraction of the surface acoustic wave as it travels over the surface of the specimen, (b) there is a real but spurious dispersion caused by SAW scattering on the rough surface, and (c) there is the principal dispersion caused material effects of the surface treatment, including the primary compressive residual stress effect and the secondary cold work effect. The results of this investigation revealed some important aspects of SAW propagation on surface treated metals and confirmed (open full item for complete abstract)

Committee: Dr. Peter Nagy (Advisor) Subjects:

Doctor of Philosophy, The Ohio State University, 2009, Civil Engineering

The present work focuses on the development of a Modular Multi-Component Coastal Ocean Prediction System (mmcops) that incorporates the full 3D wave-current interactions for a better representation of the entrainment and transport mechanics in complex deep and shallow water coastal environments. The system incorporates wind, temperature and atmospheric pressure forcing that drive the circulation, wave, sediment and bottom boundary layer model components. The effects of the wind generated surface waves on the water column and bottom layer dynamics are parametrized by the inclusion of the Stokes drift, and the wave radiation stress terms that quantify the excess of mass and momentum flux produced by the waves. Coupled wave-hydrodynamic models traditionally incorporate the radiation stress terms only into the vertically integrated momentum. Considering the fact that currents are 3D structures, the vertical variation of the radiation stress should be also considered. In the present work the 3D momentum equations are re-derived to include the full 3D impact of the radiation stresses on the currents. As a preliminary test, the system is applied to Lake Michigan with a twofold purpose: a to conduct an initial testing of the model prognostic variables with and without the effect of the waves; and b to develop a methodology required to answer whether the annually observed Spring turbidity nearshore plume in Southern Lake Michigan is transporting material from its origin in one continuous transport mode or as generated by a series of local deposition, resuspension and transport activities. To this end data collected during the EEGLE project are fully analyzed; shoreline erosion rates and texture of the eroded material were collected from various sources and via various methods and are presented for 34 shoreline segments in a uniform format; an Eulerian Particle Tracking formulation that identifies the source and origin of the various particle sizes (open full item for complete abstract)

Committee: Keith Bedford W (Advisor); Carolyn Merry J (Committee Member); Gil Bohrer (Committee Member) Subjects: Civil Engineering; Geophysics; Ocean Engineering; Oceanography

Doctor of Philosophy (PhD), Ohio University, 1998, Integrated Engineering (Engineering)

An in-situ nondestructive testing method known as Spectral-Analysis-of-Surface- Waves (SASW) method is utilized to assess the properties of materials and layer thicknesses of pavement structures. The test were performed on the OH-SHRP Test Road project. All three phases of the SASW method, including field data collection, construction of the dispersion curve and the inversion process, are presented. Besides addressing the main objective, the materials used to attach a receiver onto a pavement surface was also investigated. Alternative materials considered were of wax, putty and epoxy types. Based on test results obtained from both PCC and AC pavement types, the putty material offered the best quality of wave signal among these materials. The effect of a vertical boundary in rigid pavement on the dispersion curve is also investigated using test arrays oriented perpendicular and parallel to the pavement joint. It can be concluded that the test array and the receiver should be placed at a distance at least 5.0 ft away from the pavement joints and edge to minimize the effect of reflected wave on the dispersion curve. Finally, An inversion technique which was developed in-house is utilized. The versatility of this inversion technique is illustrated by tests performed on both rigid and flexible pavement types. The results obtained from the SASW method compare reasonably well with those obtained in laboratory tests.

Committee: Shad Sargand (Advisor) Subjects: Engineering, General

Doctor of Philosophy, University of Akron, 2007, Polymer Science

Significant interest in nanotechnology is stimulated by the fact that materials exhibit qualitative changes of properties when their dimensions approach nanometer scales. Quantization of electronic, optical, and acoustic energies with nanoscale dimensions provides exciting, novel functions and opportunities, with interests spanning from electronics and photonics to biology. Characterizing the behavior of nanoscale materials is critical for the full utilization of such novel properties, but metrology for nanostructures is not yet well developed. In particular, mechanical properties of nanoscale particles or features are critical to the manipulation and stability of individual elements, yet changes in mechanical and thermodynamic properties in nanostructured materials create complications in fabrication. This thesis involves the application of Brillouin light scattering to quantify and utilize confinement induced vibrational spectra to understand phononics and elastic properties of nanostructured materials. Measurement and proper interpretation of acoustic waves in polymeric, inorganic, and biological nanostructures provides information about elastic properties and self-assembly. Brillouin light scattering was used to study the vibrational spectra of two-dimensionally confined photoresist and silicon oxide nanolines and three-dimensionally confined poly(methyl methacrylate) spheres and spherical-like viruses. These applications extend the capabilities of Brillouin from characterization of thin films and well-defined spheres to more complex structures. Acoustic waves propagating along the polymeric and silicon oxide lines allowed determination of modulus and its anisotropy. An unexpected acoustic mode was identified in the spectra from nanolines that provided a means to measure mechanical anisotropy. In polymeric lines as narrow as 88nm, neither a change in elastic properties relative to bulk elastic values nor anisotropy in elastic constants was observed. The acoustic (open full item for complete abstract)

Committee: Alexei Sokolov (Advisor) Subjects:

Master of Science, University of Toledo, 2013, Physics

Total Internal Reflection (TIR) is the phenomenon whereby a light wave incident on a boundary is completely reflected when the wave's incidence angle exceeds a crit- ical angle. For decades there has been debate about whether amplified TIR from a medium exhibiting optical gain is possible, and desire for a theory to explain it. Authors have suggested theories both in favor and in doubt of the phenomenon's ex- istence, and experimental evidence has arose supporting the existence and seemingly simultaneously contradicting proposed theoretical models. In this thesis, reflection coefficients for plane waves are calculated by satisfying boundary conditions from Maxwell's equations at the reflecting surface for both optically lossy and gainy me- dia. Plane wave reflectivity is found to exhibit is discontinuous jump from below unity to above as the incidence angle passes through the critical angle, confirming the existence of amplified TIR. Fourier analysis is used to show that finite beams also exhibit amplified TIR, but do not experience the surprising discontinuous jump in reflectivity at the critical angle.

Committee: Victor Karpov (Advisor); Robert Deck (Committee Member); Brian Bagley (Committee Member) Subjects: Optics; Physics