Master of Engineering, Case Western Reserve University, 2024, Biomedical Engineering

Sleep waves have been studied for their effects and implications on humans. Studies have focused on different aspects to study the effects of wake and sleep periods, however, have shown conflicting results. We focus our study on the effect of slow sleep waves (< 1 Hz) characteristic of non-REM sleep on synaptic weights in vitro. We induced long-term potentiation using high-frequency stimulation in the CA3 region of the hippocampus and recorded from CA1. Low-frequency spikes were induced in vitro using halved concentrations of magnesium and calcium compared with regular artificial cerebrospinal fluid. With respect to previously induced long-term potentiation, we found a reduction of 23.67 ± 62.97 % in evoked potentials' slope, however, the decrease wasn't statistically significant. We conclude that slow sleep waves are unable to produce a significant effect on synaptic weight, and the effect produced by the solution used could be dependent on the amplitude and frequency of induced spikes.

Committee: Dominique Durand (Advisor); Chia-Chu Chiang (Committee Member); Kenneth Gustafson (Committee Member) Subjects: Biomedical Engineering; Experiments; Neurobiology; Neurosciences

Master of Science, The Ohio State University, 1968, Graduate School

Committee: Not Provided (Other) Subjects:

Doctor of Philosophy, The Ohio State University, 1986, Graduate School

Committee: Not Provided (Other) Subjects: Engineering

Doctor of Philosophy, The Ohio State University, 1972, Graduate School

Committee: Not Provided (Other) Subjects: Engineering

Doctor of Philosophy, The Ohio State University, 1971, Graduate School

Committee: Not Provided (Other) Subjects: Engineering

Doctor of Philosophy, The Ohio State University, 1966, Graduate School

Committee: Not Provided (Other) Subjects: Engineering

Master of Science in Civil Engineering, University of Toledo, 2014, Civil Engineering

The use of Lamb waves to investigate damage in thin metal plates is investigated. This study is necessary to have a thorough understanding of Lamb wave propagation characteristics, its dispersion phenomena, its behavior when scattered from minor flaws, and its ability to detect damages. Nowadays, there is a growing interest to use Lamb waves for damage detection techniques. A literature review of Lamb waves and other types of waves pertinent to their use in damage detection mechanisms is presented. Dispersion curves for aluminum plates are studied for symmetric and anti-symmetric modes. Detailed comparison between the different modes, and the merits and demerits of these wave modes which help to select an appropriate mode for use in damage detection is also explained. Different types of damage have been detected experimentally using a pitch-catch method and are verified by using Waveform Revealer and finite element software, Pzflex. Based on selected fundamental Lamb wave modes, damage inflicted by drilling a through-thickness hole in an aluminum plate has been detected experimentally using a pitch-catch method by applying mode conversion phenomena and is verified by using Waveform Revealer. Moreover, different sizes of through-thickness holes and cracks in an aluminum plate have been detected by running simulations in Pzflex and using changes in time of flight and amplitude of the wave as parameters. Based on the experimental and simulation results, it is concluded in this paper that Lamb waves are sensitive to cracks and holes in thin aluminum plates, and that these types of defects can be detected by techniques using Lamb waves.

Committee: Douglas Nims Dr. (Advisor); Brian Randolph Dr. (Committee Member); Daniel Georgiev Dr. (Committee Member) Subjects: Engineering

MS, University of Cincinnati, 2007, Engineering : Aerospace Engineering

An experimental study was implemented in order to understand the pressure generated by hydrodynamic ram. A generic box type fuel tank simulator was fabricated to study the phenomenon and was capable of containing 1000 gal in order to isolate the phases of the event and separate the effects of each. Spherical projectiles were fired into the tank and the result was measured using several instruments, which were then contrasted to better describe the event. Primarily, high-speed pressure transducers were located throughout the tank in order to compare the measured pressure with a high-speed video recording of the tank interior. In addition to standard high-speed video, a large-scale shadowgraph technique was used to visualize the pressure waves produced from the projectile impact and relate the images to the pressure transducer measurements. A high-pressure initial wave is generated at impact and is followed by the more gradual drag pressure around the projectile. The collapse of the resulting cavity, however, is shown to be the most dangerous phase in the experiment.

Committee: Dr. Peter Disimile (Advisor) Subjects: Engineering, Aerospace

Master of Architecture, The Ohio State University, 1976, Architecture

Committee: Perry Borchers (Advisor) Subjects:

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

Master of Science, The Ohio State University, 1960, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Arts, The Ohio State University, 1916, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 2006, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Arts, The Ohio State University, 1912, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Arts, The Ohio State University, 1914, Graduate School

Committee: Not Provided (Other) Subjects:

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

Committee: Not Provided (Other) Subjects:

PHD, Kent State University, 2024, College of Arts and Sciences / Department of Mathematical Sciences

We focus on problems in reaction-diffusion equations with applications to combustion. We specifically consider a special class of solutions called traveling front solutions. Moreover, we study problems where the reaction rates have stepwise ignition temperature kinetics. Three separate problems are contained in this dissertation. The first of which we consider a reaction-diffusion system describing the propagation of flames under the assumption of ignition-temperature kinetics and fractional reaction order. It was shown previously that this system admits a traveling front solution. We show that this traveling front is unique up to translations. We also study some qualitative properties of this solution using the combination of formal asymptotics and numerics. Our findings allow conjecture that the velocity of the propagation of the flame front is a decreasing function of all of the parameters of the problem: ignition temperature, reaction order and an inverse of the Lewis number. Secondly, we consider a classical model of gasless combustion in a one dimensional formulation under the assumption of ignition temperature kinetics. We study the propagation of flame fronts in this model when the initial distribution of the solid fuel is a spatially periodic function that varies on a large scale. It is shown that in certain parametric regimes the model supports periodic traveling fronts. An accurate asymptotic formula for the velocity of the flame front is derived and studied. The stability of periodic fronts is also explored, and a critical condition in terms of parameters of the problem is derived. It is also shown that the instability of periodic fronts, in certain parametric regimes, results in a propagation-extinction-diffusion-reignition pattern which is studied numerically. Finally, we formulate and analyze an elementary model for the propagation of advancing autoignition fronts in reactive co-flow fuel/oxidizer jets injected into an aqueous environment (open full item for complete abstract)

Committee: Peter Gordon (Advisor); Fedor Dragan (Committee Member); Maxim Dzero (Committee Member); Michael Hicks (Committee Member); Xiaoyu Zheng (Committee Member) Subjects: Applied Mathematics; Mathematics

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

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1970, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 2006, Graduate School

Committee: Not Provided (Other) Subjects: