Paddy Nixon

University College Dublin, Dublin, Leinster, Ireland

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Publications (152)12.93 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Resource pools are collections of computational resources (e.g., servers) which can be used by different applications in a shared way. A crucial aspect in these pools is to allocate resources so as to ensure their proper usage, taking into account workload and specific requirements of each application. An interesting approach, in this context, is to allocate the resources in the best possible way, aiming at optimal resource usage. Workload, however, varies over time, and in turn, resource demands will vary too. To ensure that optimal resource usage is always in place, resource shares should be defined dynamically and over time. It has been claimed that utility functions are the main tool for enabling such self-optimizing behavior. Whereas many solutions with this characteristic have been proposed to date, none of them presents true decentralization within the context of shared pools. In this article, we then propose a decentralized model for optimal resource usage in shared resource pools, providing practical and theoretical evidence of its feasibility.
    ACM Transactions on Autonomous and Adaptive Systems 01/2012; 7(1). · 1.00 Impact Factor
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    N. Cowzer, P. Nixon
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    ABSTRACT: Publish-subscribe systems are well suited loosely decoupled nature of the web, resulting in the messaging paradigm gaining widespread adoption and being the subject of much research. Such research has focused primarily on architectures and filtering algorithms with little evidence of performance analysis or characterization of user behavior in these widely deployed messaging paradigms. In this paper we discuss and examine implicit group messaging; an application-layer many-to-many messaging paradigm for delivering messages from publishers to specified groups of consumers. Such consumer groups are not addressed by explicit names, instead they are reached by describing the shared attributes or interests of consumers, forming easily defined implicit groups. Based on a 4 week experiment we analyze the characteristics of implicit groups and their usage. We find implicit group messaging workload to be similar to RSS in terms of group membership and update patterns; groups are typically small with few large examples and update rates vary from infrequent to more limited intervals.
    GLOBECOM Workshops (GC Wkshps), 2010 IEEE; 01/2011
  • International Journal of Simulation Systems, Science and Technology. 01/2011;
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    ABSTRACT: Resource pools are collections of computational resources which can be shared by different applications. The goal with that is to accommodate the workload of each application, by splitting the total amount of resources in the pool among them. In this sense, utility functions have been pointed as the main tool for enabling self-optimizing behaviour in such pools. The goal with that is to allow resources from the pool to be split among applications, in a way that the best outcome is obtained. Whereas different solutions in this context exist, it has been found that none of them tackles the problem we deal with in a total decentralized way. In this paper, we then present a decentralized and self-optimizing approach for resource management in shared resource pools.
    10/2010: pages 149-170;
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    ABSTRACT: This document describes the Gloss infrastructure supporting implementation of location-aware services. The document is in two parts. The first part describes software architecture for the smart space. As described in D8, a local architecture provides a framework for constructing Gloss applications, termed assemblies, that run on individual physical nodes, whereas a global architecture defines an overlay network for linking individual assemblies. The second part outlines the hardware installation for local sensing. This describes the first phase of the installation in Strathclyde University.
    06/2010;
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    ABSTRACT: Location is a core concept in most pervasive systems-and one that's surprisingly hard to deal with flexibly. Using a location model supporting a range of expressive representations for spaces, spatial relationships, and positioning systems, the authors constructed LOC8, a programming framework for exploring location data's multifaceted representations and uses. With LOC8, developers can construct complex queries by combining basic queries and additional contextual information.
    IEEE Pervasive Computing 04/2010; · 2.06 Impact Factor
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    ABSTRACT: Efforts since 2001 to design self-managing systems have yielded many impressive achievements, yet the original vision of autonomic computing remains unfulfilled. Researchers must develop a comprehensive systems engineering approach to create effective solutions for next-generation enterprise and sensor systems.
    Computer 02/2010; · 1.68 Impact Factor
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    ABSTRACT: Pervasive systems are large-scale systems consisting of many sensors capturing numerous types of information. As this data is highly voluminous and dimensional, data analysis tasks can be extremely cumbersome and time-consuming. Enabling computers to recognise real-world situations is an even more difficult problem, involving not only data analysis, but also consistency checking. Here we present Situvis, an interactive visualisation tool for representing sensor data and creating higher-level abstractions from the data. This paper builds on previous work, Clear et al. (2009) [8] through evolved tool functionality and an evaluation of Situvis. A user-trial consisting of 10 participants shows that Situvis can be used to complete the key tasks in the development process of situation specifications in over 50% less time than an improvised alternative toolset.
    Pervasive and Mobile Computing. 01/2010; 6:575-589.
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    ABSTRACT: Pervasive services may be defined as services that are available to any client (anytime, anywhere). Here we focus on the software and network infrastructure required to support pervasive contextual services operating over a wide area. One of the key requirements is a matching service capable of assimilating and filtering information from various sources and determining matches relevant to those services. We consider some of the challenges in engineering a globally distributed matching service that is scalable, manageable, and able to evolve incrementally as usage patterns, data formats, services, network topologies and deployment technologies change. We outline an approach based on the use of a peer-to-peer architecture to distribute user events and data, and to support the deployment and evolution of the infrastructure itself.
    CoRR. 01/2010; abs/1006.4746.
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    ABSTRACT: Healthcare technologies are becoming increasingly pervasive, moving from controlled clinical and laboratory settings, to real environments such as homes, acute care environments and residential care centres. As a consequence, new challenges arise in evaluating the impact of healthcare technologies and interactions in their context of use. In this paper we propose the use of a pattern language as a means of capturing experiences from researchers in the field of evaluating healthcare technologies. The potential benefits of such an approach include the availability of a centralised repository, or collaborative tool of past experiences which can contribute to the reuse of knowledge, which can encourage and improve communication between interdisciplinary members of the healthcare community and which is presented in a ‘lay’ language, understandable by all. We propose to structure the content of our pattern language along three stages of healthcare, namely home care, residential care and acute care and to organise evaluations across each of these stages in terms of physical, social, intellectual and purpose fitness.
    HCI in Work and Learning, Life and Leisure - 6th Symposium of the Workgroup Human-Computer Interaction and Usability Engineering, USAB 2010, Klagenfurt, Austria, November 4-5, 2010. Proceedings; 01/2010
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    ABSTRACT: Wireless Sensor Network (WSN) is highly budgeted by energy since sensor nodes are mostly battery-powered and deployed in hard-to-reach area for prolonged duration. Moreover radio communication is very expensive for WSN. At the same time, a substantial portion WSN applications require periodic data collection. In this paper we investigate this issue in depth and present a solution architecture: 2PDA, that eliminates repeated transmission. The solution is founded upon temporal linear correlation among sensor data. Instead of sending each data packet we model them using method of least square that exploits temporal correlation among sensor data. 2PDA observes sensor data and performs operation parameterized by application accuracy. After successful computation only the parameters of the model are sent over the radio to the application-end or sink. We have evaluated 2PDA on real-time sensor data indicating substantial energy-savings in overall transmission. We have implemented 2PDA in TinyOS for telosb sensor node that reflects its deployment plausibility in terms of memory requirement. Finally we have proposed a simplified multi-path routing strategy to enhance the reliability of data which is of prime importance in all WSN applications.
    Proceedings of the 7th ACM International Workshop on Performance Evaluation of Wireless Ad Hoc, Sensor, and Ubiquitous Networks, PE-WASUN 2019, Bodrum, Turkey, October 17-18, 2010; 01/2010
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    Ross Shannon, Aaron Quigley, Paddy Nixon
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    ABSTRACT: peer-reviewed Network visualisations use clustering approaches to simplify the presentation of complex graph structures. We present a novel application of clustering algorithms, which controls the visual arrangement of the vertices in a cluster to explicitly encode information about that cluster. Our technique arranges parts of the graph into symbolic shapes, depending on the relative size of each cluster. Early results suggest that this layout augmentation helps viewers make sense of a graph's scale and number of elements, while facilitating recall of graph features, and increasing stability in dynamic graph scenarios. SFI
    01/2010;
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    ABSTRACT: Visualisations of dynamic networks are animated over time, reflecting changes in the underlying data structure. As viewers of these visualisations, it is up to us to accurately perceive and keep up with the constantly shifting view, mentally noting as visual elements are added, removed, changed and rearranged, sometimes at great pace. In a complex data set with a lot happening, this can put a strain on the observer's perceptions, with changes in layout and visual population disrupting their internalised mental model of the visualisation, making it difficult to understand what the changes represent. We present Showtime, a novel visualisation technique which dilates the flow of time so that observers have proportionally more time to understand each change based on the density of activity in the visualisation. This is paired with a novel timeline element which tracks the flow of time visually.
    Proceedings of the International Conference on Advanced Visual Interfaces, AVI 2010, Roma, Italy, May 26-28, 2010; 01/2010
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    ABSTRACT: Software tools are used to compare multiple versions of a textual document to help a reader understand the evolution of that document over time. These tools generally support the comparison of only two versions of a document, requiring multiple comparisons to be made to derive a full history of the document across multiple versions. We present Deep Diffs, a novel visualisation technique that exposes the multiple layers of history of a document at once, directly in the text, highlighting areas that have changed over multiple successive versions, and drawing attention to passages that are new, potentially unpolished or contentious. These composite views facilitate the writing and editing process by assisting memory and encouraging the analysis of collaboratively-authored documents. We describe how this technique effectively supports common text editing tasks and heightens participants' understanding of the process in collaborative editing scenarios like wiki editing and paper writing.
    Proceedings of the International Conference on Advanced Visual Interfaces, AVI 2010, Roma, Italy, May 26-28, 2010; 01/2010
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    Lang Jia, Paddy Nixon
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    ABSTRACT: In recent years, with the rapid proliferation of new computing technologies, a variety of new computing environments have been introduced, such as decentralisation and mobility. The traditional security mechanisms are seen to be inadequate for these new environments. Trust is applied as a “soft security” to cope with new security concerns. Much research on trust systems has been carried out, it is important to identify the reliability of computational trust in different computing scenarios in order to make an enhancement. The reliability of trust systems for securing social interaction is demonstrated by showing the performance of the three trust-based systems under various scenarios in a pervasive computing environment. The focus of this paper is on enhancing trust-based systems and proposing a novel monitor model which supplements existing trust models.
    Autonomic and Trusted Computing - 7th International Conference, ATC 2010, Xi'an, China, October 26-29, 2010. Proceedings; 01/2010
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    ABSTRACT: Shared resource pools are facilities featuring a cer- tain amount of resources which can be used by different applications. For managing resources in such pools, the demand of each application can be used. Such a demand, however, is driven by the workload, which varies over time. For that reason, adaptive approaches have been proposed for the management of shared resources pools. Whereas a number of solutions exist in this context, they are either not truly decentralized or do not apply to the problem we are dealing with. In this paper, we then present Darma, an approach for managing shared resource pools in a truly decentral- ized, adaptive, and optimal way.
    Proceedings of the 18th Euromicro Conference on Parallel, Distributed and Network-based Processing, PDP 2010, Pisa, Italy, February 17-19, 2010; 01/2010
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    E. Loureiro, P. Nixon, S. Dobson
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    ABSTRACT: Resource pools are collections of computational resources which can be shared by different applications. The goal with that is to accommodate the workload of each application, by splitting the total amount of resources in the pool among them. In this sense, utility functions have been pointed as the main tool for enabling self-optimizing behaviour in such pools. The goal with that is to allow resources from the pool to be split among applications, in a way that the best outcome is obtained. Whereas different solutions in this context exist, it has been found that none of them tackles the problem we deal with in a total decentralized way. In this paper, we then present a decentralized utility maximization approach for adaptive and optimal management of shared resource pools.
    Intelligent Networking and Collaborative Systems, 2009. INCOS '09. International Conference on; 12/2009
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    Lang Jia, M. Collins, P. Nixon
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    ABSTRACT: Ubiquitous computing connects computers, places, people and everyday objects together by providing the support for social interactions in our everyday computing environment. Such interactions are usually impersonal, interpersonal and hyperpersonal, which are identified as the communications and the collaborations between entities. Since trust ensures the confidence in interactions between entities in social situations, it is critical to validate whether the use of any trust mechanism is adequate in any given environment, e.g., pervasive advertising. This paper presents a novel evaluation framework for trust-based access control (TBAC) models. The proposed framework is designed to compare several TBAC models by simulating a number of well known security attacks including the Sybil attack.
    Mobile Ubiquitous Computing, Systems, Services and Technologies, 2009. UBICOMM '09. Third International Conference on; 11/2009
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    ABSTRACT: As pervasive applications become prevalent in our day-to-day lives, the interactions of service provision and consumption between unknown and strange users are commonplace. Trust and reputation systems play a vital role in such application scenarios. One of the problems is that selfish users are reluctant to render the truthful recommendation without incentive. Even if there are incentives, self-interested users may maximise their profit by falsely declaring their opinions strategically. In this paper, we propose a strategy-proof trust mechanism which is a VCG (Vickrey-Clarke-Groves) mechanism for honest recommendation elicitation. The characteristics of the mechanism, such as the characteristics of social choice function and the properties of the payments, are also discussed. Simulation results show that our mechanism is effective in preventing strategic manipulation and guarantee that selfish users will give honest recommendations.
    Mobile Adhoc and Sensor Systems, 2009. MASS '09. IEEE 6th International Conference on; 11/2009
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    ABSTRACT: We propose a prototype for a real-world, human network proximity experiment with detailed recordings of the position of individuals. Our aim is to provide a comprehensive dataset to investigate the internal correlations between mobility and network properties, as well as to compare our results with different datasets, involving different social groups or mobile agents. As a further result, we expect the capability to formulate a model able to evaluate the relative importance of location and network centrality for efficient delay tolerant networks, with the added benefit of being able to synthesise realistic trace data for simulation.
    Ultra Modern Telecommunications & Workshops, 2009. ICUMT '09. International Conference on; 11/2009

Publication Stats

2k Citations
12.93 Total Impact Points

Institutions

  • 2006–2012
    • University College Dublin
      • School of Computer Science and Informatics
      Dublin, Leinster, Ireland
  • 2002–2010
    • University of Strathclyde
      • Department of Computer and Information Sciences
      Glasgow, Scotland, United Kingdom
  • 2009
    • Ocean University of China
      Tsingtao, Shandong Sheng, China
  • 2007
    • Dublin Business School
      Dublin, Leinster, Ireland
  • 2000
    • Trinity College
      • Computer Science
      Hartford, CT, United States
    • Dublin City University
      Dublin, Leinster, Ireland
  • 1999–2000
    • Trinity College Dublin
      • Department of Computer Science
      Dublin, L, Ireland