• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 5637
  • 2368
  • 1701
  • 1016
  • 446
  • 446
  • 446
  • 446
  • 446
  • 445
  • 391
  • 389
  • 386
  • 371
  • 368
  • Tagged with
  • 15469
  • 2827
  • 2552
  • 2357
  • 2250
  • 1991
  • 1506
  • 1352
  • 1078
  • 1004
  • 978
  • 935
  • 874
  • 736
  • 720
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Land Use-Transportation Interaction: Lessons Learned from an Experimental Model using Cellular Automata and Artificial Neural Networks

Ahrens, Steve R. 01 May 2008 (has links)
Land use and transportation interact to produce large urban concentrations in most major cities that create tremendous sprawl, noise, congestion, and environmental concerns. The desire to better understand this relationship has led to the development of land use–transport (LUT) models as an extension of more general urban models. The difficulties encountered in developing such models are many as local actions sum to form global patterns of land use change, producing complex interrelationships. Cellular automata (CA) simplify LUT model structure, promise resolution improvement, and effectively handle the dynamics of emergent growth. Artificial Neural Networks (ANN) can be used to quantify the complex relationships present in historical land use data as a means of calibrating a CA-LUT model. This study uses an ANN, slope, historical land use, and road data to calibrate a CA-LUT model for the I-140 corridor of Knoxville, TN. The resulting model was found to require a complex ANN, produce realistic emergent growth patterns, and shows promising simulation performance in several significant land classes such as single-family residential. Problems were encountered as the model was iterated due to the lack of a mechanism to extend the road network. The presence of local roads in the model’s configuration strengthened ability of the model to simulate historical development patterns. Shortcomings in certain aspects of the simulation performance point to the need for the addition of a socio-economic sub-model to assess demand for urban area and/or an equilibrium mechanism to arbitrate the supply of developable land. The model constructed in this study was found to hold considerable potential for local-scale simulation and scenario testing given suitable modification to its structure and input parameters.
82

Modeling Cellulosic Ethanol Plant Location Using GIS

Wilson, Bradly Scott 01 August 2009 (has links)
Domestically produced renewable transportation fuels have become a priority for researchers, policy makers, and investors in recent times. Ethanol, particularly cellulosic ethanol made from woody or fibrous plant material, has emerged as one such fuel that could help to ease the current dependence on foreign oil. The questions of where to build the facilities that convert feedstocks to cellulosic ethanol as well where the feedstock will come from to supply these biorefineries are important ones. This paper examines methods for using GIS to model feedstock availability and ideal biorefinery location in an economically feasible manner. The software developed as part of this study is referred to as BIOFLAME (Biofuels Facility Location Analysis Modeling Endeavor). Expanding on similar efforts that came before it, The model allows the user to perform an analysis on any combination of counties within a 16 state region in the southeast U.S. given parameters such as biorefinery capacity, crop prices, transport cost rate, feedstock yield adjustments, hay land availability, driving distance limit, required profit, and more. A suitability analysis can be performed using an array geographic features that a biorefinery might be situated near or away. A feedstock supply analysis then evaluates the costs involved in siting a facility in all candidate sites within the suitable areas. An ideal site is identified that minimizes transportation and farmgate costs. A report is generated that details the annual costs involved as well as how much and what kind of traditional cropland would be converted to switchgrass production under the scenario. The siting algorithm supports single or multiple facilities.
83

The Role of Ferry Crossings in the Development of the Transportation Network in East Tennessee, 1790-1974

Moore, Tyrel Gilce, Jr. 01 December 1975 (has links)
This thesis examines the role of ferry crossings in the development of East Tennessee's transportation network. Because of the number of streams in the area, ferries were widely used and this study traces their changing location and influence from the 1790's to 1974. The study revealed that ferry crossings were among the area's earliest internal improvements and that they were the principal method of stream crossing on regularly traveled routes from the 1790's to the late 1920's. In addition to serving as a relatively reliable means of stream crossing, ferry sites took on a variety of functions during this period. Steamboat and flatboat trade flourished in the nineteenth century and ferry landings functioned as foci for commercial activity by providing connections between river and wagon transportation. Because ferry landings were convenient collection points for agricultural items marketed in the water and wagon transport system, local trading centers and country stores were often established near them. Movements of people and goods were oriented by the pattern of routes linked by ferries and their widespread use made them vital in the regional transportation system. Ferries lost the multiple functions that they had held in the regional economy and transportation system when the automobile replaced the horse and wagon. Steam navigation declined and after the first two decades of the twentieth century the influence of ferries was diminished. By the late 1930's, the role of ferries had been reduced and they were used on less important routes in the transportation system. Prior to the twentieth century ferries were symbols of improved transportation; in the automobile era their slowness caused them to be regarded as obsolete features of the transportation network. In 1974 only five of the approximately one hundred which operated in the 1890's were still operational in East Tennessee. These ferries provided a savings of distance on routes of limited or local importance. The present ferries also serve as reminders of an historically important transportation system which shaped the past and present geography of the area.
84

Cognition, science and geography : an exploration into mental infrastructure and interdisciplinarity

Asphaug, Anders January 2006 (has links)
This text explores the significance of perspectives from the cognitive sciences for interdisciplinarity or cross-domain thinking in science, and particularly in geography. First interdisciplinarity is examined, describing some of the central conditions that such ventures exist under. The interaction between different conceptual systems is identified as a core issue in interdisciplinarity. By focusing on our conceptual systems the dissertation aims to say something general about interdisciplinarity and science, as well as focusing on what may be considered specific to geographic ways of thought. The conditions for scientific and cross-domain thinking are explored through an examination of the human mind. The problem of relating our mental microstructures to cultural and scientific phenomena is given particular attention. Evolution, it is argued, has given the human mind an ‘intuitive ontology,’ which has significance for science, especially since it incorporates deeply rooted boundaries between knowledge domains. While this is important, it is incomplete as a view of science or of a discipline. The thesis therefore seeks to supply this theory with as much context as possible in order to get a more complete understanding of scientific activities. To establish some features of the geographical way of thought, the intellectual history of the discipline is explored. Three features are particularly emphasised, namely its focus on usefulness, on synthesis, and on visual analysis. These features, it is theorised, form important parts of the explanation for why geographers often have sought to transgress boundaries despite the above mentioned intuitive ontology. The thesis is mainly a theoretical contribution, but has also an empirical component. The Department of Geography at NTNU, Trondheim is described with a dual focus on intellectual characteristics and socio-cultural characteristics. The purpose of this is to better understand the theory about human cognition and geography in light of the complexities of a concrete case. By treating the Department as a complex adaptive system, the many different factors found to be significant are sought treated within one, relatively unified conceptual system.
85

Comparison of Wild-Domestic Sheep Interaction Policies in Bighorn Disease Outbreak Locations in the Continental U.S., 1990-2010

Howard, Tristan 23 May 2013 (has links)
For over 100 years, disease has significantly limited bighorn sheep (Ovis canadensis) in the western U.S. Interaction with domestic sheep (Ovis aries) has been a primary cause of fatal bighorn disease (typically pneumonia), which has severely reduced or eliminated entire populations. Various wild-domestic sheep interaction policies exist to address the disease problem. In this analysis, six case study locations are compared and analyzed in an effort to evaluate policy efficacy. Locations examined and their bighorn die-off dates include: the Tobin Range, NV (1991); Aldrich Mountain, OR (1991); the Highland/Pioneer Mountains, MT (1994-1995); the Tarryall/Kenosha Mountains, CO (1997-2000); the Hays Canyon Range, NV (2007); and Bonner/West Riverside, MT (2010). Each location is investigated based on the policy analysis criteria of: buffer zones, herder supervision rules, trailing restrictions, consideration of domestic sheep presence prior to bighorn reintroduction, grazing allotment alteration efforts, education/negotiation attempts, fatal removal of bighorns near domestic sheep, coordination/tension between agencies, and funding difficulties. Regarding wild-domestic sheep interaction, all locations lacked clear buffer zones and trailing restrictions. At least five locations lacked funding difficulties. Where applicable, in four locations, domestic sheep presence was considered before reintroducing bighorns. In at least two locations, grazing allotment alteration was attempted, and bighorns were fatally removed. In at least five locations, agencies coordinated bighorn management, and negotiation or education was attempted. Tension between agencies existed in at least one location. From 1990-2010, the wild-domestic sheep disease issue gained prominence in policy documents, politics, and in the minds of agency biologists. This projects case studies illustrate that bighorn-domestic sheep interaction policies can be successful with diligence, but success is unpredictable and location-dependent. If bighorns and domestic sheep are to coexist in the same areas, one size-fits-all separation policies covering the entire American West will not be effective. In a strictly ecological context, not allowing domestic sheep and bighorns to share the same ranges at all is the least risky and most effective way to prevent bighorn die-offs caused by domestic sheep disease.
86

An Evaluation of Trend and Anomalies of Arctic Sea Ice Concentration, 1979-2006

Xia, Peiyao 10 May 2013 (has links)
As a part of the Cyrosphere ecosystem, Arctic sea ice is one of the focal points when studying Arctic climate change. Arctic sea ice image has been documented by remotely sensed data since the 1970s. By examining these data, some climate patterns can be revealed. In this research, Arctic region is divided into 9 sections to analyze the regional differences of the ice coverage and variability. Data used are bootstrapped 1979 to 2006 SSM/I and SMMR images from NSIDC to perform a time series analysis to examine the sea ice trends and spatial/temporal anomalies detection by conducting a descending sort of sea ice coverage by years in the sub-regional scale. Then, the temporal mixture analysis developed by Piwowar & LeDrew is applied to the data to reveal the variability within each subregion. Fractional images produced by TMA highlight the temporal signature concentration in the entire Arctic region. And the color-mix image derived from TMA highlights and overlaps temporal signatures that have over 80% concentrations from highest to lowest. The color mix image can reveal the spatial distribution of similar temporal characteristics and the evolution of time series in the same area during the 30-year period. Through this analysis, the spatial and temporal variability of Arctic sea ice can be perceived that in the subpolar regions, Arctic sea ice has a higher seasonal pattern which varies a lot each other. The Arctic sea ice extent endures an overall decline trend, which the decline speed increases every ten years. But this trend is not statistically significant in every subregion. The spatial/temporal anomaly analysis reveals several patterns of Arctic sea ice variability. The seasonal variability of Arctic sea ice in the eastern and western side of the Arctic Basin resemble each other in the long term, which may coincide with the North Atlantic Oscillation. In addition, within a subregion, different areas may have significantly different temporal characteristics, such as the Greenland Sea and Seas of Okhotsk. Moreover, the temporal characteristics some areas in the Arctic region have changed through time significantly regarding early melt or late freeze. Hopefully this analysis will provide undiscovered temporal evolution through time and some new insights on the dynamics of the Arctic sea ice cover.
87

Mapping a Historic Bitterroot Valley, Montana Landscape Using General Land Office Surveyors' Field Notes

Shelly, Karen M. 04 February 2013 (has links)
The late 1800s Bitterroot Valley, Montana, landscape and settlement patterns were summarized and mapped using the General Land Office (GLO) surveyors' field notes. Surveyors' observations of six townships from Hamilton to the Stevensville vicinity were examined in several ways. A total of 3321 points of ecological and geographic information and 422 miles of vegetation were mapped from the field notes. Surveyor information, vegetation composition, tree abundance, vegetation spatial structure and distribution of vegetation types were characterized in a multi-part historic vegetation data assemblage of point, line and polygon feature classes. Aquatic, topographic and cultural aspects of the area contributed to the historic landscape configuration. A GLO land cover classification was derived using surveyors' terminology and crosswalked with current land cover classes. The culmination of this research produced historic vegetation maps and evaluations, summaries of historic cultural, topographic and aquatic features and an unpretentious comparison of GLO vegetation to current land cover. GLO vegetation along all section lines compared to current land cover revealed differences between historic and current vegetation conditions. Highest differences were decreases in Upland Timber and Prairie-No Timber, and increases in GLO Field and Bottomland Timber near-equivalents. The current conditions of land that surveyors described as GLO Upland Timber and Prairie-No Timber were reported. The methodology applied to the Bitterroot Valley could be used to map extensive areas of Montana, providing quantitative and descriptive observations of a pre-satellite landscape.
88

The Bicycle as a Transportation Vehicle: An Assessment of Bicycle Suitability in Bowling Green, Kentucky

Gordon, Ryan 01 April 1998 (has links)
Today automobile-related problems of congestion, air pollution, and aesthetic pollution are an ever-increasing concern for urban and suburban areas. In this thesis the researcher examines the bicycle as a viable alternative transportation mode. Research examines levels of bicycle transportation around the world and in the United States. A brief historical analysis of bicycle transportation in the United States revealed that bicycling was an important mode of transportation in the late 1800s. Bicycles regained popularity in the 1970s, and many cities began to develop plans in order to handle the sudden increase in bicycling. Case studies of both foreign and domestic cities indicate some of the central aspects of bicycle planning. Different bicycle planning approaches, as well as planning benefits, are discussed. In particular, the advantages of the bicycle integration approach are stressed. The bicycle integration approach is the basis for a case study analysis of Bowling Green, Kentucky. The purpose of the analysis was to assess the local transportation infrastructure for its bicycle suitability by applying the bicycle stress level model. In addition, an inventory of the hazards and deficiencies of the transportation infrastructure was incorporated into the analysis of bicycle suitability. I concluded that the overall infrastructure in Bowling Green, Kentucky, is currently not suitable for bicycle transportation. Included in the results is a discussion of specific problem areas and maps showing the bicycle suitability of individual street segments. Recommendations are made to increase the bicycle friendliness of Bowling Green, including the overall recommendation for wide curb lanes and paved shoulders. In addition, many specific recommendations for the mitigation of hazards and the correction of infrastructure deficiencies are discussed.
89

Understanding Perceptions of Accessibility and Mobility Through Structuration Theory

Graham, Mark 01 May 2004 (has links)
Structuration theory in geography states that social systems are reproduced through the relationships between systems, structures, actors and their perceptions. Therefore, understanding the modes through which social systems are reproduced will allow for a clearer understanding of the nature of society. However, much of the relevant social theory has not been empirically tested. Thus, by empirically examining general perceptual differences between different built environments, on a macro and a micro level, it is hoped that the links between perceptions, social structures, and the built environment can be more fully understood. A better understanding of these links will, in turn, allow the relevant social theory (in this case, structuration theory) in geography to be advanced from a theoretical to an empirical stage. A clearer understanding of the links between perceptions, the built environment, and the reproduction of social systems will not only advance the field of geography, but will also have ramifications in the fields of psychology, sociology, economics, marketing, and urban planning. The purpose of this study is to examine how structural differences between locations may result in differences in people's perceptions about and interactions with the landscape. I hypothesize that there are fundamental differences in the way people perceive and interact with landscapes in Bowling Green, Kentucky, and Penzance, England, in part because of the broader structural and environmental differences between these settings. Specifically, I hypothesize that perceptions about preferred forms of transportation to leisure and retail activities will be significantly different between residents of locations that have a significant difference in the modes of transportation to such leisure and retail activities. Bowling Green and Penzance have been chosen as study sites because great differences exist between these cities in how transportation systems to leisure and retail activities are structured.
90

The Evolution of a Commercial Landscape: A Case Study of the Motels Along U.S. Highway 31-W

Brown, Jill 01 July 2002 (has links)
The cultural landscape is shaped by human imprints on the natural environment. Many decisions are made that have rippling effects over time. One type of development that changes the landscape is transportation innovation. As improved transportation links are introduced, people change their movement to include the quicker, more efficient route. As movement changes due to increased accessibility, roads that were once traveled by all now have fewer travelers. The rippling effects of the decision to add new infrastructure start at the opening of the innovation. New businesses will spring up at crossroads and common stopping areas. The long established businesses located on the old highways experience a change in business trends (transactions). The less use of the road by travelers, the less use of their businesses. This study attempts to show the effect of the transportation innovation of the Interstate System on the cultural landscape of a U.S. highway. The study area is U.S. Highway 31 -W, also known as the Dixie Highway, which runs parallel and interweaves with Interstate 65, from Elizabethtown south to Bowling Green, Kentucky. The different spatial locations of motels on 31-W and the different uses of the structures over time will be examined to determine patterns of use in relation to the nearest 1-65 interchange. The study uses nearest neighbor analysis to find patterns among the existing motel structures, and contingency/chi-square analysis to find relationships between motel locations and distances to the nearest interstate interchange and downtown center. Results show that the NNA yielded three years in which there were significant levels to reject the null hypothesis (the point pattern is random) in favor of the alternate hypothesis one (the point pattern is more clustered than random). Neither of the results of the two contingency/chisquare analyses, use of motel structure in relation to distance from the interstate and use of motel structure in relation to distance from the nearest town center, show significant evidence to favor the alternate hypothesis over the null in any of the years used.

Page generated in 0.0559 seconds