Engineering Commons^™

Fractionation & Segregation Of Suspended Particles Using Acoustic And Flow Fields, Nazhat Aboobaker

Dissertations

The fractionation of particles by size or by density has many applications in a variety of technologies. Decontamination and separation of fine sediments is useful in treating sediments. The application of acoustic standing wave fields for the fractionation and segregation of suspended particles was studied.

The above technology was implemented at the bench scale by building a Plexiglas chamber. Two ultrasound transducers were fixed to opposite sides of the chamber to generate the acoustic standing wave field. The technology was evaluated using silica dioxide (Si02) (1-5 ~tm) and silicon carbide (SiQ (5-20 ~tm) particle suspensions in deionized water. Due to …

Transit Productivity Analysis In Heterogeneous Conditions Using Data Envelopment Analysis With An Application To Rail Transit, Manuel J. Martinez

Dissertations

This dissertation extends transit productivity analysis by developing a new method of Data Envelopment Analysis (DEA), the linear programming approach to productivity analysis. The new model analyzes productivity of transit working under heterogeneous operating conditions. It is named Two-Farrell DEA for it applies DEA in two stages, DEA (1), that calculates the productivity frontiers at given operating conditions and DEA (2), that uses inputs adjusted by multipliers calculated in DEA (l). The model Two Farrell DEA calculated productivity benchmarks for each rail transit agency and estimated its potential for higher revenue or lower expense improvement. Additionally, the results identify two …

Predicting Thermodynamic And Transport Parameters For Metal Contaminant Sorption To Hydrated Metal Oxides In Aquatic Systems, Paras Trivedi

Dissertations

Hydrated oxides such as HAO,'HFO, goethite, and BA40 are prevalent in soils and sediments as discrete particles or as coatings. These microporous oxides have large surface areas and high affmity for metal ions, and hence they act as both a sink and a source for anthropogenically released metal contaminants. To better understand risks posed by metals in the environment and to develop effective waste management programs, mechanistic models are needed to accurately predict their fate in soils and sediments.

To achieve this objective, sorption of metal ions Sr, Cd, Zn, Ni, and Ca to these oxides were studied with macroscopic …

A Software System For Large-Scale Structural Optimization, Keith M. Macbain

Dissertations

This work is driven by recent developments in mathematical programming, the state-of-the-art of structural optimization, the spectacular performance of linear programming algorithms, and computer hardware developments which imply that applications of structural optimization might be used commonly in engineering design. Currently, there are few general purpose optimization routines available to the structural engineer and much of the work has addressed specific classes of problems. Further, there is little widespread use of the available routines, partly due to the large amount of familiarity one must have with the specific details of both the problem and the optimization method. In response, it …

Assessing The Economic Impact Of Aircraft Noise On Communities, Ithan B. Zimmer

Dissertations

The impact of aircraft noise on communities is complex and multi-dimensional. This matter cannot be resolved without careful analysis of a complex array of related problems and issues including the environment, the economy, and quality-of-life concerns of people living in proximity to airports or aircraft routes. The effects of community noise are widespread and varied. Impacts can include sleep and speech interference, activity interference, general annoyance, and property value decrease. In order to improve public policy and provide a foundation for additional research, it is imperative to establish the extent of a problem. Dollars are often the least common denominator …