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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Kinetics of the electrocoagulation of oil and grease

Rincon, Guillermo 20 May 2011 (has links)
Research on the electrocoagulation (EC) of hexane extractable materials (HEM) has been conducted at the University of New Orleans using a proprietary bench-scale EC reactor. The original reactor configuration forced the fluid to follow a vertical upward-downward path. An alternate electrode arrangement was introduced so that the path of flow became horizontal. Both configurations were evaluated by comparing the residence time distribution (RTD) data generated in each case. These data produced indication of internal recirculation and stagnant water when the fluid followed a vertical path. These anomalies were attenuated when the fluid flowed horizontally and at a velocity higher than 0.032 m s-1 . A series of EC experiments were performed using a synthetic emulsion with a HEM concentration of approximately 700 mg l-1. It was confirmed that EC of HEM follows first-order kinetics, and kinetic constants of 0.0441 s-1 and 0.0443 s-1 were obtained from applying both the dispersion and tanks-in-series (TIS) models, respectively. In both cases R2 was 0.97. Also, the TIS model indicated that each cell of the EC behaves as an independent continuous-stirred-tank reactor.
2

Developing and Testing an Anguilliform Robot Swimming with Theoretically High Hydrodynamic Efficiency

Potts, John B, III 18 December 2015 (has links)
An anguilliform swimming robot replicating an idealized motion is a complex marine vehicle necessitating both a theoretical and experimental analysis to completely understand its propulsion characteristics. The ideal anguilliform motion within is theorized to produce ``wakeless'' swimming (Vorus, 2011), a reactive swimming technique that produces thrust by accelerations of the added mass in the vicinity of the body. The net circulation for the unsteady motion is theorized to be eliminated. The robot was designed to replicate the desired, theoretical motion by applying control theory methods. Independent joint control was used due to hardware limitations. The fluid velocity vectors in the propulsive wake downstream of the tethered, swimming robot were measured using Particle Image Velocimetry (PIV). Simultaneously, a load cell measured the thrust (or drag) forces of the robot via a hydrodynamic tether. The measured field velocities and thrust forces were compared to the theoretical predictions for each. The desired, ideal motion was not replicated consistently during PIV testing, producing off-design scenarios. The thrust-computing method for the ideal motion was applied to the actual, recorded motion and compared to the load cell results. The theoretical field velocities were computed differently by accounting for shed vortices due to a different shape than ideal. The theoretical thrust shows trends similar to the measured thrust over time. Similarly promising comparisons are found between the theoretical and measured flow-field velocities with respect to qualitative trends and velocity magnitudes. The initial thrust coefficient prediction was deemed insufficient, and a new one was determined from an iterative process. The off-design cases shed flow structures into the downstream wake of the robot. The first is a residual disturbance of the shed boundary layer, which is to be expected for the ideal case, and dissipates within one motion cycle. The second are larger-order vortices that are being shed at two distinct times during a half-cycle. These qualitative and quantitative comparisons were used to confirm the possibility of the original hypothesis of ``wakeless'' swimming. While the ideal motion could not be tested consistently, the results of the off-design cases agree significantly with the adjusted theoretical computations. This shows that the boundary conditions derived from slender-body constraints and the assumptions of ideal flow theory are sufficient enough to predict the propulsion characteristics of an anguilliform robot undergoing this specific motion.

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