Georgios K. Theodoropoulos

Huazhong University of Science and Technology, Wu-han-shih, Hubei, China

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Publications (107)15.45 Total impact

  • Elvis S. Liu, Georgios K. Theodoropoulos
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    ABSTRACT: The past two decades have witnessed an explosion in the deployment of large-scale distributed simulations and distributed virtual environments in different domains, including military and academic simulation systems, social media, and commercial applications such as massively multiplayer online games. As these systems become larger, more data intensive, and more latency sensitive, the optimisation of the flow of data, a paradigm referred to as interest management, has become increasingly critical to address the scalability requirements and enable their successful deployment. Numerous interest management schemes have been proposed for different application scenarios. This article provides a comprehensive survey of the state of the art in the design of interest management algorithms and systems. The scope of the survey includes current and historical projects providing a taxonomy of the existing schemes and summarising their key features. Identifying the primary requirements of interest management, the article discusses the trade-offs involved in the design of existing approaches.
    ACM Computing Surveys (CSUR). 04/2014; 46(4).
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    ABSTRACT: A large scale High Level Architecture (HLA)-based simulation can be constructed using a network of simulation federations to form a “federation community”. This effort is often for the sake of enhancing scalability, interoperability, composability and enabling information security. Synchronization mechanisms are essential to coordinate the execution of federates and event transmissions across the boundaries of interlinked federations. We have developed a generic synchronization mechanism for federation community networks with its correctness mathematically proved. The synchronization mechanism suits various types of federation community network and supports the reusability of legacy federates. It is platform-neutral and independent of federate modeling approaches. The synchronization mechanism has been evaluated in the context of the Grid-enabled federation community approach, which allows simulation users to benefit from both Grid computing technologies and the federation community approach. A series of experiments has been carried out to validate and benchmark the synchronization mechanism. The experimental results indicate that the proposed mechanism provides correct time management services to federation communities. The results also show that the mechanism exhibits encouraging performance in terms of synchronization efficiency and scalability.
    Journal of Parallel and Distributed Computing 04/2013; 70(2):144-159. · 1.12 Impact Factor
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    Rachid Anane, Richard Freeland, Georgios K. Theodoropoulos
  • Vince Gaffney, PHIL MURGATROYD, BART CRAENEN, GEORGIOS THEODOROPOULOS
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    ABSTRACT: Vince Gaffney, Phil Murgatroyd, Bart Craenen, and Georgios Theodoropoulos ‘Only individuals’: moving the Byzantine army to Manzikert pp. 25-43 Traditionally, history has frequently emphasized the role of the ‘Great Man or Woman’, who may achieve greatness, or notoriety, through the consequences of their decisions. More problematic is the historical treatment of the mass of the population. Agent-based modelling is a computer simulation technique that can not only help identify key interactions that contribute to large scale patterns but also add detail to our understanding of the effects of all contributors to a system, not just those at the top. The Medieval Warfare on the Grid project has been using agent-based models to examine the march of the Byzantine army across Anatolia to Manzikert in AD 1071. This article describes the movement model used to simulate the army and the historical sources on which it was based. It also explains why novel route pla
    01/2013: pages 25-44; , ISBN: ISBN 978‐1‐905670‐49‐9
  • Qi Liu, Georgios K. Theodoropoulos, Dilma Da Silva, Elvis S. Liu
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    ABSTRACT: The increasing scale and complexity of virtualized data centers pose significant challenges to system management software stacks, which still rely on special-purpose controllers to optimize the operation of cloud infrastructures. Autonomic computing allows complex systems to assume much of their own management, achieving self-configuration, self-optimization, self-healing, and self-protection without external intervention. This paper proposes an agent-based architecture for autonomic cloud management, where resources and virtual machines are associated with worker agents that monitor changes in their local environments, interact with each other, make their own decisions, and take adaptive actions supervised by a network of management processes. To fulfill global objectives, the management processes conduct what-if simulations and update the worker agents' local rules when necessary. Such a guided decentralized decision making method can mitigate the pressure on the system management stack, improve the effectiveness of resource management, and accelerate the response to failures and attacks.
    Winter Simulation Conference; 12/2012
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    ABSTRACT: Digital Humanities offer a new exciting do-main for agent-based distributed simulation. In historical studies interpretation rarely rises above the level of un-proven assertion and is rarely tested against a range of evidence. Agent-based simulation can provide an opportu-nity to break these cycles of academic claim and counter-claim. The MWGrid framework utilises distributed agent-based simulation to study medieval military logistics. As a use-case, it has focused on the logistical analysis of the Byzantine army's march to the battle of Manzikert (AD 1071), a key event in medieval history. It integrates an agent design template, a transparent, layered mechanism to translate model-level agents' actions to timestamped events and the PDES-MAS distributed simulation kernel. The paper presents an overview of the MWGrid system and a quantitative evaluation of its perfomance.
    16th IEEE International Symposium on Distributed Simulation and Real Time Applications (DSRT 2012); 10/2012
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    ABSTRACT: Traffic simulation can be very computationally intensive, especially for microscopic simulations of large urban areas (tens of thousands of road segments, hundreds of thousands of agents) and when real-time or better than real-time simulation is required. For instance, running a couple of what-if scenarios for road management authorities/police during a road incident: time is a hard constraint and the size of the simulation is relatively high. Hence the need for distributed simulations and for optimal space partitioning algorithms, ensuring an even distribution of the load and minimal communication between computing nodes. In this paper we describe a distributed version of SUMO, a simulator of urban mobility, and SParTSim, a space partitioning algorithm guided by road network for distributed simulations. It outperforms classical uniform space partitioning in terms of road segment cuts and load-balancing.
    The 16th IEEE/ACM International Symposium on Distributed Simulation and Real Time Applications; 01/2012
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    ABSTRACT: Historical studies are frequently perceived to be characterised as clear narratives defined by a series of fixed events or actions. In reality, even where critical historic events may be identified, historic documentation frequently lacks corroborative detail that supports verifiable interpretation. Consequently, for many periods and areas of research, interpretation may rarely rise above the level of unproven assertion and is rarely tested against a range of evidence. Simulation provides an opportunity to break cycles of academic claim and counter-claim. This paper discusses the development and utilisation of large scale distributed Agent-based simulations designed to investigate the medieval military logistics in order to generate new evidence to supplement existing historical analysis. The work aims at modelling logistical arrangements relating to the battle of Manzikert (AD 1071), a key event in Byzantine history. The paper discusses the distributed simulation infrastructure and provides an overview of the agent models developed for this exercise.
    International Journal of Humanities and Arts Computing 01/2012;
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    E.S. Liu, G.K. Theodoropoulos
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    ABSTRACT: As the scale of Distributed Virtual Environments (DVEs) grows in terms of participants and virtual entities, using interest management schemes to reduce bandwidth consumption becomes increasingly common for DVE development. The interest matching process is essential for most of the interest management schemes which determines what data should be sent to the participants as well as what data should be filtered. However, if the computational overhead of interest matching is too high, it would be unsuitable for real-time DVEs for which runtime performance is important. This paper presents a new approach of interest matching which divides the workload of matching process among a cluster of computers. Experimental evidence shows that our approach is an effective solution for the real-time applications.
    Distributed Simulation and Real Time Applications (DS-RT), 2011 IEEE/ACM 15th International Symposium on; 10/2011
  • JOHN HALDON, Vince Gaffney, Georgios Theodoropoulos, Phil Murgatroyd
    Dumbarton Oaks Papers 01/2011; 65/66:209-235.
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    Computational and Mathematical Organization Theory 01/2011; · 0.42 Impact Factor
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    15th IEEE International Symposium on Distributed Simulation and Real Time Applications (DSRT 2011); 01/2011
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    B.G.W. Craenen, G.K. Theodoropoulos
    The Fifth International Conference on Innovative Mobile and Internet Services in Ubiquitous Computing (IMIS-2011); 01/2011
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    Agent Directed Simulation Symposium (ADS 2011), Spring Simulation Multiconference (SpringSim 2011); 01/2011
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    B.G.W. Craenen, V. Suryanarayanan, G.K. Theodoropoulos
    DIstributed SImulation & Online gaming (DISIO 2011); 01/2011
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    Olufunmilola Onolaja, Georgios Theodoropoulos, Rami Bahsoon
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    ABSTRACT: Reputation and trust-based models have been used extensively in different application domains. These include large online communities such as eBay, Amazon, YouTube and ad-hoc and wireless sensor networks. Recently, the use of the models has gained popularity due to their effectiveness in providing trusted systems or networks. Thesemodels focus on online and historical data to determine the reputation of domain members. In this paper, we propose a novel approach for obtaining trust values by focusing not only on online and historical data but also possible future scenarios to anticipate events in the next time intervals. The data-driven framework is able to dynamically obtain and inject data to predict the future trust value of every identity in the system. The advantage of this proactive approach compared to other approaches is that informed decisions about the domain can be made before a compromise occurs.
    Procedia CS. 01/2011; 4:1751-1760.
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    Olufunmilola Onolaja, Rami Bahsoon, Georgios Theodoropoulos
    Trust Management V, 5th IFIP WG 11.11 International Conference, IFIPTM 2011, Copenhagen, Denmark, June 29-July 1, 2011, Proceedings; 01/2011
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    Vincent Gaffney, Philip Murgatroyd, Bart Craenen, Georgios Theodoropoulos
    In Digital Classicist: A Supplement of the Bulletin of the Institute of Classical Studies. 01/2011;
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    E.S. Liu, G.K. Theodoropoulos
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    ABSTRACT: Interest management provides scalable data distribution for large-scale distributed virtual environments by filtering irrelevant messages on the network. The interest matching process is essential for most of the interest management schemes which determines what data should be sent to the participants as well as what data should be filtered. Most of the existing interest matching approaches focus on reducing the computational overhead of the matching process. However, they have a fundamental disadvantage - they perform interest matching at discrete time intervals. As a result, they would fail to report events between two consecutive time-steps of simulation. If participants ignore these missing events, they would most likely perform incorrect simulations. This paper presents a new algorithm for continuous interest matching which aims to capture missing events between discrete time-steps. Although our approach requires additional matching steps, we employ a efficient algorithm to significantly reduce this overhead.
    Principles of Advanced and Distributed Simulation (PADS), 2010 IEEE Workshop on; 06/2010
  • G.K. Theodoropoulos, P. Murgatroyd, V. Gaffney, B.G.W. Craenen
    Universitas 21 Digital Humanities Conference "Cultural Heritage and Technology"; 01/2010

Publication Stats

693 Citations
15.45 Total Impact Points

Institutions

  • 2013
    • Huazhong University of Science and Technology
      Wu-han-shih, Hubei, China
  • 2000–2013
    • University of Birmingham
      • • School of Computer Science
      • • Centre for Systems Biology (CSB)
      Birmingham, England, United Kingdom
  • 2004–2008
    • Coventry University
      Coventry, England, United Kingdom
  • 2001–2006
    • University of Nottingham
      • School of Computer Science
      Nottigham, England, United Kingdom
  • 1996–1997
    • The University of Manchester
      • School of Computer Science
      Manchester, ENG, United Kingdom