Evaluation of accessibility of urban transportation networks

This thesis examines accessibility of urban networks to serve the transportation needs of a community. The term accessibility is dealt with qualitatively and quantitatively, giving it a form and structure readily adaptable for implementation by metropolitan planning organizations. Accessibility has been defined from the point of view of the network. This definition helps in interfacing the network with the traditional travel demand models. A methodology was enunciated to develop accessibility indices for urban areas and implemented by means of automated software. The trip generation stage in the traditional urban transportation planning process (UTPP) is used along with a geographic information system (GIS) based approach in order to develop a program that evaluates accessibility measures and presents them in a graphical manner. The indices are expected to aid transportation planners, managers of public agencies and decision makers to make the best use of available resources in making changes to the transportation system and also help compare the system accessibility both within the system and across various systems in a region. The methodology has been implemented and an alternatives analysis performed for the Las Vegas Metropolitan area. The implementation scheme utilizes the spatial analysis capabilities of GIS and interfaces with the UTPP. A suite of programs are developed in the GIS environment to automate the process to a simple menu driven system. Twenty-two indices have been defined and analyzed for the study area. These include five indices each for trip production and attraction parameters namely home-based work, home based school, home based shop, home based other and aggregate accessibility indices. Similarly, a combined model incorporating both the production and attraction models (consisting of six indices) and a demographic model (consisting of five indices) are also developed and analyzed

The Foraging and Habitat Ecology of Black Terns in Maine

The population of Black Terns in Maine is small and factors related to the ecology of this species’ foraging and habitat ecology might limit population growth and recovery. The objectives were to (1) determine if diet and provisioning rates are limiting chick growth, (2) identify and rank suitable habitat in Maine, and (3) determine if precipitation patterns and water level dynamics are limiting in Maine. I compared growth rates of chicks in 1998-2000 in Maine to rates from other studies, determined the influence of colony, year, and diet on growth rates and food deliveries and used an energetics model to determine the sensitivity of growth rates to feeding parameters. To identify potential wetland habitat, I used a Geographic Information System analysis of National Wetlands Inventory data from Maine based on the following criteria: wetland complexes were \u3e5 ha total area with \u3e1 ha open water and contained semi-permanently flooded emergent wetland. To assess effects of flooding, I determined the probability of occurrence for 3 levels (low, moderate, and catastrophic)?of nest losses associated with flooding, based on nest loss data and stream gauge and precipitation data for 1960-1999. Growth rates of Black Tern chicks in Maine ( ? = 4.46 g/d) were similar to other studies (range 4.18-5.18 g/d) and varied with hatch order and brood, but not year or colony. Third-hatched chicks (of 3) grew most slowly ( ? = 4.15 g/d) but at greater rates than one reported estimate (3.32 g/d) for starved chicks. Patterns of food deliveries were complex. The ratio of fish to insects in the diet ranged from 3.4-13.3, and total delivery rates varied widely (9.1-23.7 items/brood-hr), but there was no evidence that growth rates differed among diets. Weight change in chicks was best predicted by delivery rates of large fish, large and small insects, and temperature; however, modeling indicated that growth rates were most sensitive to rates of large insect delivery. My results indicate that diet type did not influence growth rates of chicks at the observed rates of delivery, and overall there was no evidence that food resources limited fledging rates in Black Terns in Maine. I identified 730 potential colony sites for Black Terns in Maine. Potential sites ranged in size from 5-30,864 ha ( ? = 425 ha) and had 0.04-228 ha of semipermanently flooded emergent wetland. However, only 51 sites were classified as high potential sites (\u3e20 ha of semi-permanently flooded emergent wetland) The availability of potential sites does not appear to be limiting the population of Black Terns in Maine, but these sites should be ground surveyed because wetland classification data may be out-dated or too coarse-grained. Moderate flooding events have the potential to cause the greatest long-term effect on nesting success in Maine because of a high frequency of occurrence (38% of years)?and \u3e50% nest loss in the largest colony and 36% in other colonies. Small flooding events occurred often (70% of years), but resulted in few nest losses and catastrophic flooding events caused extensive nest losses (\u3e94% in the largest colony and 36% in other colonies) but occurred in only 13% of years

Unified Heat Kernel Regression for Diffusion, Kernel Smoothing and Wavelets on Manifolds and Its Application to Mandible Growth Modeling in CT Images

We present a novel kernel regression framework for smoothing scalar surface data using the Laplace-Beltrami eigenfunctions. Starting with the heat kernel constructed from the eigenfunctions, we formulate a new bivariate kernel regression framework as a weighted eigenfunction expansion with the heat kernel as the weights. The new kernel regression is mathematically equivalent to isotropic heat diffusion, kernel smoothing and recently popular diffusion wavelets. Unlike many previous partial differential equation based approaches involving diffusion, our approach represents the solution of diffusion analytically, reducing numerical inaccuracy and slow convergence. The numerical implementation is validated on a unit sphere using spherical harmonics. As an illustration, we have applied the method in characterizing the localized growth pattern of mandible surfaces obtained in CT images from subjects between ages 0 and 20 years by regressing the length of displacement vectors with respect to the template surface.Comment: Accepted in Medical Image Analysi

Three-dimensional structure and kinematics of the Piedras-Girardot foldbelt in the northern Andes of Colombia

Detailed geologic mapping, strain analysis, and simple stratigraphic principles indicate that deformation in the Piedras-Girardot foldbelt in the northern Andes began in the early Campanian with incipient propagation of faults that uplifted gentle domes where the accumulation of some sandy units did not take place. Maastrichtian unroofing of a metamorphic terrane west of the Piedras-Girardot foldbelt is documented by a conglomerate that was deformed shortly after deposition developing a conspicuous intragranular fabric of microscopic veins that accommodate little extension (between 1 and 2 percent in a general northeast-southwest direction). This extensional fabric, distortion of fossil molds, and a moderate cleavage most likely developed concurrently, during and after incipient late Cretaceous folding, but before large scale Paleogene faulting and folding. Cleavage also seems to record small amounts of contraction in a general northwest-southeast direction. Paleogene folding and thrust sheet propagation is recorded by syntectonic strata, and records westward to southwestward propagation of faults. Mesoscopic fabric elements associated with continuous Paleogene deformation are nearly absent, and apparently were passively rotated and translated along thrust sheets. Neogene deformation took place only in the norhtwestern flank of this foldbelt. As a result of this history of deformation, a complex array of faults and folds exists: northwest- and west-verging thrust faults, north- and northeastverging normal faults, and north- and northeast-trending strike-slip faults. Changes in the structural trend delineate a sigmoidal sinistral stepover in this dextral system, with faults verging outwardly in opposite directions defining a positive flower structure

The influence of contributing area on the hydrology of the prairie pothole region of North America

This thesis formulates a conceptual framework developed from field observations that describes the influence of surface depressions or potholes on runoff generation in the prairie pothole region of the North American prairies. The fill-and-spill of potholes results in intermittent surface water connectivity between potholes within the basin. The extent of connectivity between potholes is dependent on antecedent water levels. Dynamic connectivity between potholes results in dynamic contributing areas for runoff. The concept of connectivity is manifested in the conceptual curves presented in this thesis. These conceptual curves model the response of runoff events for landscape types found in the prairie pothole region, and capture the influence of the spatial distribution and extent of surface storage on contributing area. The conceptual curves differ due to variations in the spatial distribution and extent of surface storage volume. An algorithm based on the conceptual framework proposed is presented. The algorithm, which uses the the D-8 drainage direction method, automates a methodology for identifying and quantifying runoff contributing area. The algorithm is applied in prairie pothole basins both to demonstrate its efficacy and to test the potential for using conceptual curves to describe the relationship between decreasing potential surface storage in the landscape and contributing area. The algorithm was applied to two digital elevation models (DEM) representative of the prairie pothole region. The first DEM was created using LiDAR elevation points at a 1 m resolution for the St. Denis watershed, and the second was created from orthophotos for the Smith Creek watershed at a 25 m resolution. Fieldwork in the St. Denis watershed was carried out to both provide a basis for the conceptual framework proposed and to validate the results of the algorithm. The fieldwork involved gathering snow survey data, identifying and describing surface water conditions during a snow melt runoff event in 2006, and measuring pond levels from 2004 – 2007. Results indicate that the proposed conceptual curves represent the non-linear relationship between potential surface storage and contributing area generated by the algorithm in the test basins. To test whether the underlying concepts of the algorithm were valid, the algorithm was used to model pond level depths measured in the St. Denis drainage basin after spring runoff in 2006 and 2007. An r2 value over 0.9 was calculated for the relationship between measured and modeled pond levels in both years. Based on this work, it is clear that any hydrologic study or model applied in the prairie pothole region should consider the effect of dynamic contributing areas on runoff generation

Development of a GIS-based routing model

Route optimization models deal with multi-criteria or multi-objective optimization problems. The basic objectives of routing problems include transport cost and risk affects. An improved model presented in this thesis addresses a new optimization model, Range Optimization Model . Although the core of the route optimization tools adopted is still the conventional Shortest Path Algorithm , the definition of route optimization functions and the means to employ Shortest Path Algorithm are different from conventional procedures; Geographic Information Systems (GIS), have been widely used as a spatial database management system and a geographical analysis tool in a variety of fields related to study of environment, transportation engineering, planning and geographical analysis. This thesis develops a prototype GIS-based routing system which includes static routing functions, dynamic routing functions, and emergency response analysis functions. The system implements the route optimization function based on Network Analysis tools and Dynamic Segmentation capabilities of ARC/INFO. By employing multiple input-source menu systems, user-friendly interfaces are designed for users to easily define problems, select the features, perform route selections, edit routes, and query route information in both graphic form and tabular form. (Abstract shortened by UMI.)