Physical Sciences and Mathematics Commons^™

Modeling Spring Catchment Discharge: A Case Study Of Candela, Panama, Central America, Jordan P. Van Sickle

Dissertations, Master's Theses and Master's Reports

Where the proper geological and hydrological conditions exist, natural springs have provided a reliable source of clean water to mankind for eons. Changing climates and land development can negatively impact spring source replenishment and threaten their reliability as a source of water. In the face of prospects of diminishing supplies and increasing population demands, community leaders question whether and how to invest in development for enhancing sustainability and protecting water quality, causing water managers to dispute their reliability given decreasing flows. Springs located in the rugged jungle of western Panama serve as the primary water supply for many indigenous communities, …

Experimental Study Of The Flow Of Ferrofluid In A Porous Media Under A Magnetic Field, Muskaan Khurana

Dissertations, Master's Theses and Master's Reports

This research presents results from a laboratory-scale experimental setup that was designed to visualize the behavior of ferrofluid percolation through a porous media. Ferrofluids are colloidal suspensions made of magnetic particles of a few nanometers and stabilized in carrier liquids like water or mineral oil. Ferrofluids get magnetized and align themselves in the direction of a magnetic field when a field gradient is applied.

With the help of this experiment we investigate the viability of controlling fluid flow in porous medium by a magnetic field in vicinity. The experiments show that ferrofluids can be used as a transporting media to …

Influence Of The Weathered Layer On Retrieving Body Wave Using Passive Siesmic Interferometry, Boming Wu

Dissertations, Master's Theses and Master's Reports

Passive seismic interferometry (SI) is an increasingly popular seismic method due to its cost-efficient advantage because it does not need an active source. Techniques in using SI to retrieve surface waves are relatively well established, but using SI to retrieve body waves is still under development by many authors. These geophysicists have proved that many factors, such as average duration of the natural sources, the number of natural sources that occurred during recording time, source distribution, etc., influence the quality of body waves retrieved. In this research, I focus on how to make use of the attenuation property of weathered …

An Assessment Of The Validity Of The Kinetic Model For Liquid-Vapor Phase Change By Examining Cryogenic Propellants, Kishan Bellur

Dissertations, Master's Theses and Master's Reports

Evaporation is ubiquitous in nature and occurs even in a microgravity space envi- ronment. Long term space missions require storage of cryogenic propellents and an accurate prediction of phase change rates. Kinetic theory has been used to model and predict evaporation rates for over a century but the reported values of accommodation coefficients are highly inconsistent and no accurate data is available for cryogens. The proposed study involves a combined experimental and computational approach to ex- tract the accommodation coefficients. Neutron imaging is used as the visualization technique due to the difference in attenuation between the cryogen and the metallic …

Laboratory Measurements Of Contact Nucleation By Mineral Dusts, Bacteria, And Soluble Salts, Joseph Niehaus

Dissertations, Master's Theses and Master's Reports

We present results from experiments that emulate atmospheric ice nucleation by aerosols. We have refined experimental techniques to improve measurements of ice forming nuclei in the contact mode. Our results show that atmospherically relevant dusts such as kaolinite, feldspar, rhyolitic ash, and Arizona Test Dust have efficiencies in the contact mode that are higher than the immersion mode. Experiments with bacteria show that biological material has the potential to contribute significantly to ice concentrations, but has large variability. By choosing a soluble compound as an ice nucleus, we are able to place bounds on the timescale for contact freezing and …

Improved Parameter Estimation Of The Log-Logistic Distribution With Applications, Joseph Reath

Dissertations, Master's Theses and Master's Reports

In this report, we work with parameter estimation of the log-logistic distribution. We first consider one of the most common methods encountered in the literature, the maximum likelihood (ML) method. However, it is widely known that the maximum likelihood estimators (MLEs) are usually biased with a finite sample size. This motivates a study of obtaining unbiased or nearly unbiased estimators for this distribution. Specifically, we consider a certain `corrective' approach and Efron's bootstrap resampling method, which both can reduce the biases of the MLEs to the second order of magnitude. As a comparison, we also consider the generalized moments (GM) …

The Role Of Amino Acids In The Nitrogen Cycle Of Peatlands, Tia Scarpelli

Dissertations, Master's Theses and Master's Reports

Future release of carbon from peatlands in response to climate change may be impacted by nitrogen limitation. The current study considers the role of amino acids as a nitrogen source in peatlands. The total free amino acid (TFAA) concentration for peats ranged from 0-2.3 µM, and leucine was the primary contributor. The dominance of sedge or ericaceous shrub plant types did not significantly impact the TFAA pool. Ammonium concentrations were much greater than TFAA and nitrate concentrations. TFAA concentrations were greatest in spring and least in fall. The springtime maxima and summer decrease in concentrations were simulated in a modeling …

Personas: A Strategy For More Inclusive And Usable Reproductive Health Tracking Technologies, Anna R. Paul

Dissertations, Master's Theses and Master's Reports

In this report, I argue for the inclusion of personas in the development process of technologies that are designed to allow users to collect and track their health information. Personas provide a profile of a user and their needs, goals, and contexts. This tool can help designers to better understand their users, in order to create better, more usable end products. I examine one particular self-tracking technology, smartphone applications that allow users to record information about their menstrual cycles. Many of the most popular period tracking applications available today only meet the needs of a narrow user group, resulting in …

Assessing The Impacts Of Climate Change On The Surface Temperature Of Inland Lakes In Michigan, Kaitlin Reinl

Dissertations, Master's Theses and Master's Reports

The aim of this study was to validate and apply a lake model for predicting the susceptibility of small inland lakes in Michigan to changes in thermal regime and increased cyanobacteria growth as a result of future climate conditions. The Freshwater Lake Model was selected, tested for sensitivity to various inputs, and validated through comparison to observed conditions. The sensitivity analysis showed that the lake model was most sensitive to solar radiation, air temperature, and air humidity. Comparison of predicted climate data with observed conditions revealed highly variable climate model error. The lake model validation was conducted using 10 lakes …