Infrastructure Engineering - Research Publications
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ItemComputational structure in three-valued nearness relations(Springer, 2001)The development of cognitively plausible models of humanspatial reasoning may ultimately result in computational systems thatare better equipped to meet human needs. This paper explores how humansubjects perceive the qualitative spatial relation nearness within anenvironmental space. Based on experimental data, a three-valued nearnessrelation is analysed in two stages. First, the results are analysedwith special reference to the existence of subsets of candidate landmarkplaces, from which nearness relations between other places may be partiallyinferred. Second, the desirable properties of such landmark setsare considered and some of their formal properties are presented. Theseproperties are then considered in the light of the data furnished by theexperiment. The paper concludes with a discussion of the signicance ofthe analyses and the scope for further work in this area.
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Item"Simplest" paths: automated route selection for navigation(Springer, 2003)Numerous cognitive studies have indicated that the form andcomplexity of route instructions may be as important to human navigatorsas the overall length of route. Most automated navigation systemsrely on computing the solution to the shortest path problem, and not theproblem of finding the “simplest” path. This paper addresses the issueof finding the “simplest” paths through a network, in terms of the instructioncomplexity. We propose a “simplest” paths algorithm that hasquadratic computation time for a planar graph. An empirical study ofthe algorithm’s performance, based on an established cognitive model ofnavigation instruction complexity, revealed that the length of a simplestpath was on average only 16% longer than the length of the correspondingshortest path. In return for marginally longer routes, the simplest pathalgorithm seems to offer considerable advantages over shortest paths interms of their ease of description and execution. The conclusions indicateseveral areas for future research: in particular cognitive studies areneeded to verify these initial computational results. Potentially, the simplestpaths algorithm could be used to replace shortest paths algorithmsin any automated system for generating human navigation instructions,including in-car navigation systems, Internet driving direction servers,and other location-based services.
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ItemA formal model of obfuscation and negotiation for location privacy(Springer, 2005)Obfuscation concerns the practice of deliberately degradingthe quality of information in some way, so as to protect the privacy ofthe individual to whom that information refers. In this paper, we arguethat obfuscation is an important technique for protecting an individual’slocation privacy within a pervasive computing environment. The papersets out a formal framework within which obfuscated location-based servicesare defined. This framework provides a computationally efficientmechanism for balancing an individual’s need for high-quality informationservices against that individual’s need for location privacy. Negotiationis used to ensure that a location-based service provider receivesonly the information it needs to know in order to provide a service ofsatisfactory quality. The results of this work have implications for numerousapplications of mobile and location-aware systems, as they providea new theoretical foundation for addressing the privacy concerns thatare acknowledged to be retarding the widespread acceptance and use oflocation-based services.
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ItemSimulation of obfuscation and negotiation for location privacy(Springer, 2005)Current mobile computing systems can automatically sense and communicatedetailed data about a person’s location. Location privacy is an urgent researchissue because concerns about privacy are seen to be inhibiting the growthof mobile computing. This paper investigates a new technique for safeguardinglocation privacy, called obfuscation, which protects a person’s location privacy bydegrading the quality of information about that person’s location. Obfuscation isbased on spatial imperfection and offers an orthogonal approach to conventionaltechniques for safeguarding information about a person’s location. Imprecisionand inaccuracy are two types of imperfection that may be used to achieve obfuscation.A set of simulations are used to empirically evaluate different obfuscationstrategies based on imprecision and inaccuracy. The results show that obfuscationcan enable high quality of service in concert with high levels of privacy.