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  • 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.
1

Urban Fringe and Transportation Corridor Convection-Diffusion Model for Anthropogenically-Initiated Wildfire Ignition Prediction

Sadasivuni, Ravi Raj 14 December 2013 (has links)
A novel approach for modeling anthropogenically-initiated wildfire ignition was developed that significantly advances the theoretical knowledge of human-wildfire interactions. Gravity interaction models that are commonly used for economic analyses associated with business competition were combined with fluid dynamics models that mimic human movement patterns to predict the probability of anthropogenically-initiated wildfire. Herein, a combined gravity interaction and fluid dynamics models is developed and validated for wildfire potential prediction against historic and current wildfire data. The study identified population centers and transportation corridors, in particular: proximity to railroads and roads; traffic volume; and density of the corridors as the most influential factors for wildfire ignition. The population centers are identified as global influencing factors, and are modeled as the gravity term. The transportation corridors are identified as local influencing factors, and are modeled using fluid flow analogy as diffusion and convection terms. An analytic convection diffusion model (CDM) model is derived and the model coefficients calibrated using historic wildfire data. The model is implemented in GIS, and applied for the prediction of wildfire potential prediction in southeastern Mississippi. The model shows a correlation of R2=0.87 against winter historic data, whereas the Gravity model with a fuel component shows only R2=0.75 correlations. The improved predictions using the proposed CDM model is due to its capability to predict both the global and the local measure of incendiary activity patterns within a single dynamic equation. The CDM model can be used as a standalone model that can predict the wildfire potential in a region. It can also be combined with the fuel layer and meteorological conditions to obtain spatio-temporal variation of wildfire risks, which would provide a decision support system for wildfire mitigation and land use planning and development. The CDM model will help fire managers better plan wildfire mitigation (fuel reduction) strategies and effectively stage equipment and personnel geographically in areas of drought that are coincident with high ignition probability. Land use and transportation managers will gain better understanding of the changes in wildfire risk pattern due to urban fringe development.
2

Gravity Model to Detect Forest Fire Prone Areas in the Southeast Fire District of Mississippi

Sadasivuni, Raviraj 05 May 2007 (has links)
The human risk as a spatial component using Newton?s Gravity model is explored for the first time in this research along with fuels and road density variables to predict the fire occurrences for Southeast Mississippi fire district. The fire risk map indicated that fires occur in clusters and are dependent on fire size and distance from roads. The results proved that fire size increases as fire locations increase. Fire locations decrease significantly beyond 160 meters with increasing road distance. The Gravity model proved to be a better estimator of fire risk while a similar road density model proved to be better in very low and medium fire risk zones. Compared to road density, the gravity model significantly proved a better estimate of very low fire risk for all seasons and summer low fire risk. For all other fire risks, though, gravity model showed better results no significant differences were observed.
3

Evaluating Neural Spatial Interaction Modelling by Bootstrapping

Fischer, Manfred M., Reismann, Martin January 2000 (has links) (PDF)
This paper exposes problems of the commonly used technique of splitting the available data in neural spatial interaction modelling into training, validation, and test sets that are held fixed and warns about drawing too strong conclusions from such static splits. Using a bootstrapping procedure, we compare the uncertainty in the solution stemming from the data splitting with model specific uncertainties such as parameter initialization. Utilizing the Austrian interregional telecommunication traffic data and the differential evolution method for solving the parameter estimation task for a fixed topology of the network model [ i.e. J = 9] this paper illustrates that the variation due to different resamplings is significantly larger than the variation due to different parameter initializations. This result implies that it is important to not over-interpret a model, estimated on one specific static split of the data. (authors' abstract) / Series: Discussion Papers of the Institute for Economic Geography and GIScience
4

Embodying space : Capture Image Gallery

Naude, Elmarie 08 December 2009 (has links)
The city of Pretoria has a diverse mix of people moving in and around it. This dynamic, ever-changing movement, combined with the city’s cultural diversity, renders it ideal for an investigation into the relationship (or lack thereof) that exists between the moving body and architectural space. The city and its architectural spaces are viewed as static. The human body and its movement is dynamic. These static spaces cannot always accommodate the dynamic movement taking place within and around them. This leads to a lack of dialogue or interaction between the two, causing a tension which is further aggravated by the fact that they are situated within a constantly changing environment. The aim of this thesis is not only to examine the relationship between the city and the human body moving through its architectural spaces, but also to provide the platform for an investigation into the establishment of an active dialogue between the two. CAPTURE is envisaged as an experimental laboratory in the city of Pretoria. It aims to rejuvenate the city’s CBD, as well as to develop and promote arts and culture through the creation of a public exhibition space. It is a design intervention intended to create a space which captures and navigates its users through it, by exposing them to the different functions facilitated within it, as well as to the space and to each other. The introduction of this spatial intervention, informed by the existing pedestrian movement through an identified public thoroughfare, will encourage an active dialogue between the user and the space. Public art, in the form of the photographic image, has been identified as a possible means of communicating the user’s surroundings to him/her. This, in turn, may encourage interaction with, and interpretation of the space. / Dissertation (MInt(Prof))--University of Pretoria, 2009. / Architecture / unrestricted
5

Applications of Geographic Information Systems in Planning for Pedestrian Trail Bridges in Nepal

Devkota, Bhuwan Bahadur January 2007 (has links)
Rural accessibility is a pressing issue in many parts of the world. Improved geographical accessibility to basic social service facilities for rural populations is a goal of most governments in developing countries. Development of a trail-based transport system is a key way to improve rural accessibility in mountainous and rugged terrain where trails criss-cross with numerous rivers. The present study focuses on Nepal, a developing country with rural accessibility challenges and a very challenging physical environment. This thesis reviews the existing accessibility patterns in rural areas of Nepal and proposes various approaches for identifying poorly served geographical areas and optimizing of location of additional new trail bridges to provide “best” links to social services. The methodology in this study is based on the concept of the gravity-based spatial interaction and accessibility models. GIS applications are used in different ways, such as in creating, acquiring, integrating spatial and attribute datasets, and spatial analysis and visualization of the output results. Amongst the different types of social services, health care and education centers are considered the most pressing services and hence are the objects of analysis. The main difference between health care service centers and educational facilities is that schools are usually very widespread across the district and serve for the school age population. Health service centers are sparsely and inequitably distributed, however, they serve the whole population at large. The results of the analysis show a fairly clear indication of problems relating to rural transport and access to social service centers in rural Nepal. This is attributed, in part, due to insufficient provision of social service centers and the lack of trail bridges over river crossing locations. The estimated numbers of trips over potential new bridges based on spatial integration modeling provides a basis for prioritization of river crossing locations for allocation of new trail bridges. The poorly served areas across the study district are identified on the basis of the results of the potential accessibility modeling. The trail network nodes with relatively low accessibility values are of prime concern and the subject of contemplation in the trail bridge planning decision-making process.
6

Applications of Geographic Information Systems in Planning for Pedestrian Trail Bridges in Nepal

Devkota, Bhuwan Bahadur January 2007 (has links)
Rural accessibility is a pressing issue in many parts of the world. Improved geographical accessibility to basic social service facilities for rural populations is a goal of most governments in developing countries. Development of a trail-based transport system is a key way to improve rural accessibility in mountainous and rugged terrain where trails criss-cross with numerous rivers. The present study focuses on Nepal, a developing country with rural accessibility challenges and a very challenging physical environment. This thesis reviews the existing accessibility patterns in rural areas of Nepal and proposes various approaches for identifying poorly served geographical areas and optimizing of location of additional new trail bridges to provide “best” links to social services. The methodology in this study is based on the concept of the gravity-based spatial interaction and accessibility models. GIS applications are used in different ways, such as in creating, acquiring, integrating spatial and attribute datasets, and spatial analysis and visualization of the output results. Amongst the different types of social services, health care and education centers are considered the most pressing services and hence are the objects of analysis. The main difference between health care service centers and educational facilities is that schools are usually very widespread across the district and serve for the school age population. Health service centers are sparsely and inequitably distributed, however, they serve the whole population at large. The results of the analysis show a fairly clear indication of problems relating to rural transport and access to social service centers in rural Nepal. This is attributed, in part, due to insufficient provision of social service centers and the lack of trail bridges over river crossing locations. The estimated numbers of trips over potential new bridges based on spatial integration modeling provides a basis for prioritization of river crossing locations for allocation of new trail bridges. The poorly served areas across the study district are identified on the basis of the results of the potential accessibility modeling. The trail network nodes with relatively low accessibility values are of prime concern and the subject of contemplation in the trail bridge planning decision-making process.
7

Spatial econometric methods for modeling origin destination flows

LeSage, James P., Fischer, Manfred M. 11 1900 (has links) (PDF)
Spatial interaction models of the gravity type are used in conjunction with sample data on flows between origin and destination locations to analyse international and interregional trade, commodity, migration and commuting patterns. The focus is on the classical log-normal model version and spatial econometric extensions that have recently appeared in the literature. These new models replace the conventional assumption of independence between origin-destination flows with formal approaches that allow for spatial dependence in flow magnitudes. The paper also discusses problems that arise in applied practice when estimating (log-normal) spatial interaction models. (authors' abstract)
8

Exploring spatial interactions

Bruner, Ryan David 08 August 2012 (has links)
The field of interaction design is constantly shifting with the introduction of new technologies that allow individuals the ability to interact with or act upon an environment, such as installations that use motion tracking as an input device, or allowing users to interact with an environment with their mobile device. This shift from the interaction with traditional computers (static machines) to machines that react to people and environments, requires designers to reevaluate how these new platforms can be effectively used to communicate information and have a lasting affect on participants. There is a great challenge in the articulation of new interaction models. Many people tend to hold on to more traditional or familiar methods of interacting with their devices, as these new methods of engagement require the learning of new metaphors for interaction. How do we construct systems that engage and motivate people to use unfamiliar systems? The work presented in this report is my attempt to answer this question by exploring emerging spatial interface technologies. / text
9

Fiscal Federalism and Spatial Interactions among Governments

Chen, Longjin 01 January 2012 (has links)
This dissertation examines multiple state and local expenditure categories in the United States to expand understanding of fiscal federalism and spatial interactions among governments. First, the author investigates the relationship between police expenditures and crime rates from a spatial perspective. Both police expenditures and crime rates in one state are found to exhibit a similar pattern to that in neighboring states. Spatial correlation is also detected between police expenditures and crime rates. As police of neighbors in fact deter crime at home, there are positive externalities present among the states. Second, the author conducts new tests on the Leviathan hypothesis, i.e., more competition, smaller government. While cost efficiency is used in place of government size to capture the idea that fiscal decentralization reduces wasteful expenditures, spatial interaction is taken as another measure for decentralization. The hypothesis is supported by some evidence from total, police, highway, and welfare expenditures.
10

Spatial interaction and local government expenditures for functionally impaired in Sweden

Birkelöf, Lena January 2009 (has links)
The thesis consists of an introductory part and three self-contained papers. Paper [I] studies the determinants of the differences in expenditure on services for functionally impaired individuals among municipalities in Sweden. A spatial autoregressive model is used in order to test whether the decisions on the expenditure level in a neighboring municipality affect the municipality’s own expenditure. The results show of spatial interaction among neighbors, possible due to mimicking. However, when controlling for differences among counties there is no evidence of spatial interaction. Therefore, the positive interaction first found can be interpreted either as a result of differences in the way county councils diagnose individuals or due to interaction among the neighbors in the same county. Paper [II] takes advantage of a new intergovernmental grant in two ways. First, the grant is used to study the effect on municipal spending related to the grant. Second, the grant is used to test a hypothesis of spatial interaction among municipalities due to mimicking behavior. The data used pertains to the periods before and after the introduction of the grant. A fixed-effects spatial lag model is used to study the spatial interactions among municipalities. The results show that before the grant, municipalities interact with their neighbors when setting the expenditure level, while there is no evidence of interaction in the second period. This would support the hypothesis that the grants provide information to the municipalities and the need for mimicking diminishes with the grant. Paper [III] examines whether local public expenditures on services to functionally impaired individuals crowd out other local public expenditures in Sweden. The hypothesis is tested on five different spending areas using a two-stage least squares (2SLS) fixed-effects model. While the results give no support for crowding out in the areas of social assistance, culture & leisure, and childcare & preschool, a negative relationship on spending for elderly & disabled care and on spending for education is found, suggesting that crowding out indeed occurs within the municipal sector. The negative relationships are significant both in a statistical and an economic sense.

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