Geography Commons^™

Autonomous Robot Navigation In Unknown Terrains Using Parallel Numerical Artificial Potential Fields, John C. Schneider

Computer Science Theses & Dissertations

We present a new artificial potential field formulation for resolution complete robot navigation that unifies the purely geometric path planning problem with the lower level force control problem. Our formulation is designed for numerical computation over a massively parallel mesh of processors and is responsive to newly discovered terrain features. It does not suffer from many of the problems commonly associated with potential fields and with adequate resolution provides provably correct, collision free convergence to the goal. In addition, our formulation supports many desirable, practical features required for implementation, such as bounded actuator torques, attainable incremental constructability, realizable computation and …

The Ethnic Aspects Of Population Change In Latvia After Independence, Ilmars Mezs

Masters Theses

This study examines current and historic ethnic and demographic trends and their spatial and cultural contexts within Latvia. Comparisons with the other two Baltic states are also presented and discussed. The Latvian population underwent fifty years of Soviet rule, with deliberate policies to dilute the homogeneity of Latvians through Russification, in-migration, and political dominance. The period from 1940 to 1991 greatly impacted Latvians and immigrants, who were mainly Russians, by placing stresses on the spatial structure of the ethnic groups and their cultural relationship.

Latvians in particular feared ethnic and cultural extinction. The process of ethnic dilution and mixing under …

Gis Application For Nitrogen Dioxide Pillution Monitoring In Moscow, Russia, Maria V. Privalsky

Masters Theses

The focus of this study was nitrogen dioxide pollution monitoring in Moscow, Russia. ERDAS GIS was used to create maps of nitrogen dioxide distribution on the territory of the city for the years from 1983 to 1991.

A special model was written to compare the consecutive pairs of years in respect to the nitrogen dioxide pollution change. Results of model application were analyzed in order to determine the territories that experienced maximum changes during the study period.

Relationship between street density as a measure of car flow and nitrogen dioxide pollution was estimated. Two measures of the relationship were used: …

Flow Kinematics And Dynamics Of The Gulf Stream From Composite Imagery, Caitlin Patrice Mullen

OES Theses and Dissertations

A unique set of contemporaneous satellite-tracked drifters and five-day composite satellite images of the North Atlantic is studied in order to infer the near-surface flow kinematics and dynamics of the Gulf Stream. Using fractal and spectral analyses, two kinematic models, and a potential vorticity model, detailed comparisons are made between these data sets.

Fractal and spectral analyses show that the data set is not fractal, there is no geographic variability, and there is not a strong fractal scaling link between the drifter trajectories and composite temperature fronts as had been postulated by several investigators. These results indicate considerably more work …

Soil Properties And Behavior Of Earthflows In The Mt. Hood National Forest, Oregon, Douglas Andrew Smith

Dissertations and Theses

Soils from two active earthflows, two earthflow deposits, and three non-earthflow landforms are examined to determine if a connection exists between near-surface soil properties and rates of earthflow movement. The study area is located in the Clackamas Ranger District of the Mt. Hood National Forest in the northern Oregon Cascades. Its geology consists of clay-bearing volcaniclastic formations overlain by unaltered flows of andesite and basalt, a combination that contributed to large-scale landsliding during the late Pleistocene. Deposits from these landslides now cover much of the valley floor, and it is from these deposits that earthflows tend to mobilize. The main …

An Assessment Of The Riparian-Influenced Salmonid Habitat Features Of Johnson Creek, Portland, Oregon, Andrew Greiff Gude

Dissertations and Theses

Pacific salmon populations in Johnson Creek, Portland, Oregon have been adversely impacted by urbanization, and by residential and agricultural land development. Ecological impacts include loss or depletion of riparian vegetation features which directly influence stream and associated salmonid ecology. This research examines the nearstream riparian zone's contribution to instream habitat complexity for anadromous salmonids in Johnson Creek. Visual surveys were conducted on over half the stream length. Five features were assessed to determine the extent of riparian influenced stream habitat including, overhead enclosure, overhanging vegetation, undercut banks, and large and small woody debris and root wads. The stream survey showed …

"A Handsomely Improved Place" : Economic, Social, And Gender-Role Development In A Backcountry Town, Carlisle, Pennsylvania, 1750-1810, Judith A. Ridner

Dissertations, Theses, and Masters Projects

As a social history of the town and people of Carlisle, Pennsylvania from 1750 to 1810, this dissertation traces the evolution of communal identity in the early American backcountry. By focusing on the growth and development of one urban community, this work details not only how and why one group of backcountry inhabitants took pride in their town's outward accomplishments and material prosperity, but also explains how Carlisle's evolutionary growth prompted the town's people to see themselves as key players in an economic and social universe that stretched far beyond the geographic boundaries of their localized realm.;Using state and county …

A Test Of The Multiquadric Method Of Interpolation Using Drumlin Data From The Lunenburg, Nova Scotia And Peterborough, Ontario, Fields, Catherine Treena Conrad

Theses and Dissertations (Comprehensive)

The multiquadric method of interpolation has been used to generate surfaces from irregularly distributed points of geophysical data, and has proven to be a successful means of mapping such data. There are four stages involved in the implementation of the method (Saunderson, 1994): (1) solution of a system of simultaneous, linear equations; (2) interpolation of new z values, for a number of locations within the x,y area of an initial sample space of points; (3) plots of all the z values at their respective locations, using colour graphics instead of contouring; and (4) plots of the partial derivatives of z …

The International Diffusion Of The Mormon Church, Samuel Otterstrom

Theses and Dissertations

This thesis outlines the international diffusion and growth of the Church of Jesus Christ of Latter-day Saints, or Mormon Church. A model of Mormon spatial diffusion in foreign countries is developed incorporating both a functional and spatial perspective. The functional perspective includes supply and demand variables which influence the rate of growth of the Mormon Church in a country. The functional perspective is not fully explored in the thesis. The spatial perspective which the study concentrates on seeks to show a general spatial pattern related to the spread of the Church within countries.

The original diffusion of the Church to …

A Test Of The Multiquadric Technique Of Interpolation With An Application To Fluid Speeds In A River (Ontario), James Patrick Dozois

Theses and Dissertations (Comprehensive)

Hardy's (1971) technique of interpolation was tested using fluid speed data from Big Otter Creek, a gravel bed stream, in South-Western Ontario. Fourteen cross-sections were selected from a 500 m-long reach of the river. Each cross-section was divided into 10 verticals. Fluid speed was sampled as different positions in these verticals starting at 0.025 m off the channel bed using an electromagnetic current metre. Bed roughness at each cross-section was determined by collecting samples of the bed material and by measuring the long, intermediate and short axes of particles at the 10 verticals. To test the multiquadric technique of interpolation, …