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Full-Text Articles in Physical Sciences and Mathematics

Assessing Drought Vegetation Dynamics At The Landscape Scale In Semiarid Grass- And Shrubland Using Mesma, Rowan Converse May 2020

Assessing Drought Vegetation Dynamics At The Landscape Scale In Semiarid Grass- And Shrubland Using Mesma, Rowan Converse

Geography ETDs

New Mexico experienced substantial impacts of regional-scale drought from 2011-2014. Global climate change may make such events a new normal for the southwest: drought events are expected to increase in both frequency and severity over the coming century. While semiarid grasslands recover quickly from short-term drought, the cumulative impacts of climate change may reduce the resiliency of these systems over time. Remote sensing methods can allow efficient and cost-effective comparison of ecosystem recovery from drought events over time using long-running imaging systems like Landsat. We investigate the efficacy of using multi-endmember spectral mixture analysis (MESMA) to quantify the impacts of …


Drinking Water Governance For Whom? An Institutional Analysis Of Rural Drinking Water Systems In New Mexico, Tucker Colvin Apr 2020

Drinking Water Governance For Whom? An Institutional Analysis Of Rural Drinking Water Systems In New Mexico, Tucker Colvin

Geography ETDs

Rural community drinking water systems in New Mexico are facing many challenges, including a lack of personnel, deteriorating infrastructure, lack of funds, overly burdensome and confusing regulation, environmental concerns, and concerns over water rights. Governing agencies are creating vulnerability by making managers prioritize some issues and neglect others. Water systems designated a Mutual Domestic Water Consumers Associations are especially problematic because they are small and managed by volunteers but have as much regulatory burden as larger municipalities. I use the theory of institutional work to explain how an institution that was originally designed to help low-income and rural communities is …


Nonlinear Least Squares 3-D Geolocation Solutions Using Time Differences Of Arrival, Michael V. Bredemann Apr 2020

Nonlinear Least Squares 3-D Geolocation Solutions Using Time Differences Of Arrival, Michael V. Bredemann

Mathematics & Statistics ETDs

This thesis uses a geometric approach to derive and solve nonlinear least squares minimization problems to geolocate a signal source in three dimensions using time differences of arrival at multiple sensor locations. There is no restriction on the maximum number of sensors used. Residual errors reach the numerical limits of machine precision. Symmetric sensor orientations are found that prevent closed form solutions of source locations lying within the null space. Maximum uncertainties in relative sensor positions and time difference of arrivals, required to locate a source within a maximum specified error, are found from these results. Examples illustrate potential requirements …