Department of Civil and Environmental engineering

Spreadsheet optimization using a range of nonlinear error functions was utilized for parameter estimation of the two-phase pressure-saturation models developed by van Genuchten, Brutsaert, Russo and Kosugi. The data was obtained from the UNSODA database (US Salinity Laboratory, Riverside, California). Results show that spreadsheet optimization is a practical platform for evaluations based on minimizing nonlinear error functions, consequently allowing for a broader mathematical approach to parameter estimation. An error function representing the sum of the squares of errors provided the best fit for a majority of the soils evaluated, although the fractional error function provided the best fit for silts and loams. Outcomes indicated that the van Genuchten parameters m and n may also be estimated individually as opposed to following the published relationship of m = 1 − 1/n.

A mathematical model of turbulent density-driven flows is presented and is solved numerically. A form of the k–ϵ turbulence model is used to characterize the turbulent transport, and both this non-linear model and a sediment transport equation are coupled with the mean-flow fluid motion equations. A partitioned, Newton–Raphson-based solution scheme is used to effect a solution. The model is applied to the study of flow through a circular secondary sedimentation basin.

A mathematical model of turbulent density-driven flows is presented and is solved numerically. A form of the k--E turbulence model is used to characterize the turbulent transport, and both this non-linear model and a sediment transport equation are coupled with the mean-flow fluid motion equations. A partitioned, Newton-Raphson-based solution scheme is used to effect a solution. The model is applied to the study offlow through a circular secondary sedimentation basin.

The use of plastic media was evaluated for modeling sedimentary processes in rivers using a moveable bed model (MBM). From gradations within the range of 0.17-2 mm, the size of the thermoset plastic media was color coded in order to better visualize complex flow processes. Equations developed by Engelund-Hansen (1967) and Schoklitsch (1962) were used to predict sediment transport in order to establish the type of bed channel typified by the media. Similitude and scaling principles were used in order to create a virtual river reach as a replica of the model. Based on the physical properties of the media and data collected during simulations, the results suggest that the thermoset plastic media can be used to model coarse sand and gravel in MBM. ii DEDICATION This work is dedicated to my beloved wife Lita and our soon-to-be-born son Wisdel together with my affectionate mother Marie and my dear uncle Aleus-Paul. iii ACKNOWLEDGEMENTS Although this work stems from arduous and persevering efforts and sacrifices from my part, I am not less indebted to:  God whose tender care and guidance have led me thus far.  FULBRIGHT/LASPAU who sponsored my study at SIUC.  Mr. Gough who provided financial and didactic supports for this work.  Dr. Chevalier, for her outstanding work and support as my academic advisor.

A mathematical model of turbulent density-driven flows is presented and is solved numerically. A form of the k-E turbulence model is used to characterize the turbulent transport, and both this non-linear model and a sediment transport equation are coupled with the mean-flow fluid motion equations. A partitioned, Newton-Raphson-based solution scheme is used to effect a solution. The model is applied to the study offlow through a circular secondary sedimentation basin.

The recent energy crisis has triggered significant attention on the microbial synthesis of lipids, which comprise the raw material for biodiesel production. Microbial oil accumulation with filamentous fungi has great potential because filamentous fungi can form pellets during cell growth, and these pellets are much easier to harvest from cell broth. This paper focuses on the cell pelletization process of the oleaginous Mucor circinelloides. We have studied the effect of various cultural conditions on pelletized cell growth and lipid accumulation. This study is the first to report that pH adjustment during cell growth plays a key role in pellet formation of M. circinelloides and describes a handy method by which to induce cell pelletization in submerged fungal cultivation. Our study reveals that cell growth and lipid production are not significantly affected by pelletization and that lipid accumulation is triggered at stressed conditions, such as a high carbon-to-nitrogen ratio and high temperature.

Microbial oil accumulation via oleaginous fungi has some potential benefits because filamentous fungi can form pellets during cell growth and these pellets are easier to harvest from the culture broth than individual cells. This research studied the effect of various culture conditions on the pelletized cell growth of Mucor circinelloides and its lipid accumulation. The results showed that cell pelletization was positively correlated to biomass accumulation; however, pellet size was negatively correlated to the oil content of the fungal biomass, possibly due to the mass transfer barriers generated by the pellet structure. How to control the size of the pellet is the key to the success of the pelletized microbial oil accumulation process.

Electrical Resistivity Imaging (ERI) and Induced Polarization (IP) are the non-destructive and rapid methods used
for mapping the subsurface. This paper presents an application of these methods for erodibility characterization.
These tests and Erosion Function Apparatus (EFA) tests were conducted on identical samples with plasticity
indices ranging from low to high to establish a correlation of ERI, IP and erosion rates. Erosion rate and erosion
category were determined through the analysis of soil Electrical Resistivity (ER) and IP values. Then, the ERI and
IP surveys were performed at a site that had CPT data to analyze the subsurface soil layers. In order to verify the
developed correlation, three holes were hand augured and Shelby tube samples were extracted from the site to
conduct EFA testing. The results show that ER and IP methods can be used to predict soil erosion characterization
in the preliminary stages of bridge site developments with concerns about erosions around bridge piers.