Computing Distance to the Nearest Utility: As the Crow Flies vs. As the Gas Flows

The purpose of this paper is to describe an automated geographic information system (GIS) process to estimate the length of pipeline required to provide utility service to a potential customer base using the street rights-of way. Using a case study application for a large gas utility company, we compare this method to the traditional method based on straight-line Euclidean, or as-the-crow-flies, distances. The GIS method using the street rights-of-way provides a substantially more accurate estimate of the length of required pipeline than the as-the-crow-flies method does. The improvement is particularly significant when the potential customers are located a substantial distance from existing pipelines. With improved estimates of required pipeline length, utilities can pre-qualify potential customers for marketing opportunities.     

Maintenance mechanisms of plankton populations in frontal zones in the Benguela and Angola Current systems: a preface

This preface provides the background to, and synthesis of research findings from, a set of environmental research-driven cruises off southern Angola, Namibia and South Africa during February–March 2002, under the auspices the BENguela Environment Fisheries Interaction and Training (BENEFIT) Programme. The cruises formed part of the BENEFIT Shipboard Research Training Programme. Besides coastal upwelling characteristics of this eastern boudary current region, hydrographic discontinuities, strong fronts and low-oxygen conditions also appear to play an important role in the distribution of the life history of zoo- and ichthyoplankton populatios.     

Virtual City Design Based on Urban Image Theory

Abstract

This paper aims to evaluate what effect applying residents' urban image to virtual city design (a real time virtual model of an actual city) has on wayfinding performance during 'flying-based' navigation mode. Two experiments were conducted to compare two virtual city designs using the virtual model of Tel Aviv city. One design included highlighted urban elements from the residents' urban image, while in the second design no highlighted elements were included.

The experiments proved that using the elements of the residents' urban image in a virtual city design enhances the performance of all participants in the wayfinding tasks, and especially those with a low level of spatial knowledge. Analysis of the trajectory patterns and the verbal reports of the participants during navigation showed that the urban image design facilitates a more intensive use of a position-based strategy, in addition to the path-integration wayfinding strategy, which was found to be dominant in the virtual model without the highlighted urban image elements. On the basis of these findings we propose principles for designing virtual cities from a perspective of wayfinding.