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Distributed Simulation and Real Time Applications, 2009. DS-RT '09. 13th IEEE/ACM International Symposium on

Date 25-28 Oct. 2009

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Displaying Results 1 - 25 of 47
  • [Front cover]

    Page(s): C1
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  • [Title page i]

    Page(s): i
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  • [Title page iii]

    Page(s): iii
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  • [Copyright notice]

    Page(s): iv
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  • Table of contents

    Page(s): v - viii
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  • Message from General Co-chairs

    Page(s): ix
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  • Message from Program Co-Chairs

    Page(s): x
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  • Organizing Committee

    Page(s): xi
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  • Program Committee

    Page(s): xii
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  • list-reviewer

    Page(s): xiii
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  • Steering Committee

    Page(s): xiv
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  • Switching to High Gear: Opportunities for Grand-Scale Real-Time Parallel Simulations

    Page(s): 3 - 10
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (814 KB) |  | HTML iconHTML  

    The recent emergence of dramatically large computational power, spanning desktops with multi-core processors and multiple graphics cards to supercomputers with 105 processor cores, has suddenly resulted in simulation-based solutions trailing behind in the ability to fully tap the new computational capacity. Here, we motivate the need for switching the parallel simulation research to a higher gear to exploit the new, immense levels of computational power. The potential for grand-scale real-time solutions is illustrated using preliminary results from prototypes in four example application areas: (a) state- or regional-scale vehicular mobility modeling, (b) very large-scale epidemic modeling, (c) modeling the propagation of wireless network signals in very large, cluttered terrains, and, (d) country- or world-scale social behavioral modeling. We believe the stage is perfectly poised for the parallel/distributed simulation community to envision and formulate similar grand-scale, real-time simulation-based solutions in many application areas. View full abstract»

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  • On the Efficiency of LifeBelt Based Crowd Evacuation

    Page(s): 13 - 20
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    To support the evacuation process of crowds from emergency situations, we have developed a wearable device, LifeBelt, for vibro tactile guidance of individuals in panic towards exits. Since visual and auditory perception is overwhelmed in situations of panic, exit sign and loudspeaker based evacuation often appears ineffective. LifeBelt as a coordinated navigation device builds on a subtle directional vibration stimulation to navigate and guide individuals to escape. This paper compares the effectiveness of a LifeBelt supported vs. non-supported evacuation from spaces with multiple exits. Based on an extended Moore's model of neighborhood for next step behavior, and a predicted shortest time to escape metric, we investigate on the efficiency effect of (i) individuals following the nearest exit (without LifeBelt), and (ii) individuals adhering LifeBelt recommendations towards the earliest escape exit. Large scale simulations show that even in situations of growing panic, LifeBelt improves evacuation efficiency by more than 34,5%. View full abstract»

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  • An Aspect-Oriented Approach for Disaster Prevention Simulation Workflows on Supercomputers, Clusters, and Grids

    Page(s): 21 - 30
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    Computer simulation is an important factor in today's disaster prevention procedures. Simulation codes assess the evolution and impact of various physical phenomena in domains such as nuclear and environmental sciences, and ultimately help saving lives. However, new and more computationally demanding models, and new regulations for personnel training have increased the demand for computational power. While the existing simulation codes can be ported to computing environments that can meet the new demand, such as supercomputers, clusters, and grids, it is too expensive and time-consuming to rewrite and re-certify them. Instead, in this work we propose an aspect-oriented approach that takes existing simulation functionality and combines it with functionality required to run the simulation on different computing environments transparently to the simulation developer. Through experiments in the DAS-3 multi-cluster grid we show that our approach increases the reusability, the maintainability, the scalability, and the robustness of a real disaster prevention simulation, while incurring a low performance overhead. View full abstract»

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  • Benchmarking Memory Management Capabilities within ROOT-Sim

    Page(s): 33 - 40
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (482 KB) |  | HTML iconHTML  

    In parallel discrete event simulation techniques, the simulation model is partitioned into objects, concurrently executing events on different CPUs and/or multiple CPU-Cores.In such a context, run-time supports for logical time synchronization across the different simulation objects play a central role in determining the effectiveness of the specific parallel simulation environment. In this paper we present an experimental evaluation of the memory management capabilities offered by the ROme OpTimistic Simulator (ROOT-Sim). This is an open source parallel simulation environment transparently supporting optimistic synchronization via recoverability (based on incremental log/restore techniques) of any type of memory operation affecting the state of simulation objects, i.e., memory allocation, deallocation and update operations. The experimental study is based on a synthetic benchmark which mimics different read/write patterns inside the dynamic memory map associated with the state of simulation objects. This allows sensibility analysis of time and space effects due to the memory management subsystem while varying the type and the locality of the accesses associated with event processing. View full abstract»

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  • Synchronised Range Queries

    Page(s): 41 - 47
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    In this paper, we present and evaluate a system for performing logical-time synchronised Range Queries over data in the context of parallel and distributed simulations of Multi-Agent Systems (MAS). MAS are often extremely complex and simulation is commonly used to understand their behaviour or investigate the implications of alternative agent architectures. Range Queries are widely used in various fields such as Peer to Peer systems, Wireless communications or Database systems. They are key to many MAS models as they are commonly used to represent the spatial perceptive abilities of the agents in the MAS. PDES-MAS (Parallel and Discrete Event Simulation for Multi-Agent Systems) is a decentralised, discrete event simulation (DES) system which can be used to distribute and run a large scale MAS simulation over a parallel computation architecture. This paper presents a design for Logical-Time synchronised Range Queries and the implementation and evaluation of this design within the PDES-MAS system. View full abstract»

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  • Multi-user Gaming on the Grid Using a Service Oriented HLA RTI

    Page(s): 48 - 56
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    Interactive multi-user Internet games require frequent state updates between players to accommodate the great demand for reality and interactivity. The large latency and limited bandwidth on the Internet greatly affects the game's scalability. The High Level Architecture (HLA) is the IEEE standard for distributed simulation with its Data Distribution Management (DDM) service group assuming the functionalities of interest management. With its support for reuse and interoperability and its DDM support for communication optimization, the HLA is promising at supporting multi-user gaming on the Internet. However, this usually requires particular prior security setup across administrative domains according to the specific Run Time Infrastructure (RTI) used. We have previously developed a Service Oriented HLA RTI (SOHR) which enables distributed simulations to be conducted across administrated domains on the Grid. This paper discusses multi-user gaming on the Grid using SOHR. Specifically, a maze game is used to illustrate how SOHR enables users to join a game conveniently. Experiments have been carried out to show how DDM can improve the communication efficiency. View full abstract»

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  • An Approach for Parallel Interest Matching in Distributed Virtual Environments

    Page(s): 57 - 65
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1123 KB) |  | HTML iconHTML  

    Interest management is essential for real-time large-scale distributed virtual environments (DVEs) which seeks to filter irrelevant messages on the network. Many existing interest management schemes such as HLA DDM focus on providing precise message filtering mechanisms. However, this leads to a second problem: the computational overhead of the interest matching process. If the CPU cost of interest matching is too high, it would be unsuitable for real-time applications such as multiplayer online games for which runtime performance is important. This paper evaluates the performance of existing interest matching algorithms and proposes a new algorithm based on parallel processing. The new algorithm is expected to have better computational efficiency than existing algorithms and maintain the same accuracy of message filtering as them. Experimental evidence shows that our approach works well in practice. View full abstract»

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  • Latency and User Performance in Virtual Environments and Augmented Reality

    Page(s): 69
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (113 KB) |  | HTML iconHTML  

    System rendering latency has been recognized by senior researchers, such as Professor Fredrick Brooks of UNC (Turing Award 1999), as a major factor limiting the realism and utility of head-referenced display systems. Latency has been shown to reduce the user's sense of immersion within a virtual environment, to disturb user interaction with virtual objects, and to contribute to motion sickness during some simulation tasks. Latency, however, is not just an issue for external display systems since finite nerve conduction rates and variation in transduction times in the human body's sensors also pose problems for latency management within the nervous system. Some of the phenomena arising from the brain's handling of sensory asynchrony due to latency will be discussed as a prelude to consideration of the effects of latency in interactive displays. The causes and consequences of the erroneous movement that appears in displays due to latency will be illustrated with examples of the user performance impact provided by several experiments. These experiments will review the generality of user sensitivity to latency when users judge either object or environment stability. Hardware and signal processing countermeasures will also be discussed. In particular the tuning of a simple extrapolative predictive filter not using a dynamic movement model will be presented. Results show that it is possible to adjust this filter so that the appearance of some latencies may be hidden without the introduction of perceptual artifacts such as overshoot. Several examples of the effects of user performance will be illustrated by three-dimensional tracking and tracing tasks executed in virtual environments. These experiments demonstrate classic phenomena known from work on manual control and show the need for very responsive systems if they are intended to support precise manipulation. The practical benefits of removing interfering latencies from interactive systems will be emphasized with so- me classic final examples from surgical telerobotics and human-computer interaction. View full abstract»

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  • MediVol: A Practical Initial Evaluation of Refined, 3D, Interactive Volumetric Representations of Soft Tissue Pathologies in Virtual Environments

    Page(s): 73 - 81
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (805 KB) |  | HTML iconHTML  

    Effective processing of source data matched to appropriate visualisation can greatly enhance the user's ability to explore and comprehend complex information. While this is a fundamental problem for many domains, in medical applications it is particularly important. None-invasive scanning technologies, such as MRI, have greatly enhanced our ability to `image' the internal body, however the resultant visualisation is often difficult to comprehend due to both inadequacies in the scanning process and sub-optimal approaches to visualisation and data representation. These factors impose significant cognitive load on the user, requiring skill and experience to accurately comprehend detail and intense concentration, and in less experienced users, to understand the structures present. Our broader research aims to identify whether 3D representations of MRI data sets offer a more intuitive means of viewing the data and thereby enable easier understanding and comprehension of the scanned body region. As part of this research we have constructed a 3D MRI viewing application, raaMediVol, which utilises recent developments in 3D computer graphics hardware, to present an interactive environment that enables the user to view both traditional 2D slice representations and an enhanced 3D volumetric form that is freely explorable and configurable both on traditional 2D computer desktop displays and within immersive projection technologies (IPTs)[1]. Initial evaluation of the two representational paradigms been undertaken through the comparative assessment of experienced clinicians' performance in diagnosing a range of soft tissue pathologies within the shoulder, displayed in both traditional 2D slice, and evolved 3D volumetric representational form. An overview of the application, its technical operation, and the results of the evaluation trials are presented. View full abstract»

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  • Human Flesh Search Model Incorporating Network Expansion and GOSSIP with Feedback

    Page(s): 82 - 88
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (343 KB) |  | HTML iconHTML  

    With the development of on-line forum technology and the pervasive participation of the public, the Human Flesh Search is becoming an arising phenomenon which makes a great impact on our daily life. There arose big research interests in social, legal issues resulted from HFS, however, very little work has been conducted to understand how it comes into being and how it dynamically evolves. This paper proposes a modeling and simulation approach incorporating network expansion and GOSSIP propagation with feedback for a better understanding of the human flesh search phenomenon. Based on the acquisition and analysis of the netizens' surfing behavior data, the evolution of the HFS is modeled as a network growth process with proper dynamic input, which is characterized by heavy-tail and burst-oriented distribution, modeling as a Weibulloid process. Then, an improved GOSSIP model with feedback is proposed to represent the information propagation, processing and aggregation during the HFS. New insights for HFS are gained through a set of simulation experiments. View full abstract»

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  • Comparing the End to End Latency of an Immersive Collaborative Environment and a Video Conference

    Page(s): 89 - 94
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    Latency in a communication system can result in confusing a conversation through loss of causality as people exchange verbal and non-verbal nuances. This paper compares true end-to-end latencies across an immersive virtual environment and a video conference link using the same approach to measure both. Our approach is to measure end-to-end latency through filming the movements of a participant and their remote representation through synchronised cameras. We also compare contemporary and traditional immersive display and capture devices, whilst also measuring event latency taken from log files. We compare an immersive collaborative virtual environment to a video conference as both attempt to reproduce different aspects of the face-to- face meeting, the former favouring appearance and the latter attention. Results inform not only the designers of both approaches but also set the requirements for future developments for 3D video which has the potential to faithfully reproduce both appearance and attention. View full abstract»

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  • Scenario-Based Diameter-Bounded Algorithm for Cluster Creation and Management in Mobile Ad hoc Networks

    Page(s): 97 - 104
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    The construction of stable and adaptive clusters providing good performance and faster convergence rate with minimal overhead is a challenging task in Mobile Ad hoc Networks (MANETs). This paper proposes a clustering technique for MANETs, which is distributed, dominating set based, weighted and adaptive to changes in the topology called Distributed Scenario-based Clustering Algorithm for Mobile ad hoc networks (DSCAM). The election of clusterheads and gateway nodes is based on (k, r) - Dominating set, where k is the minimum number of clusterheads per node in the network and r is the maximum number of hops between a node and its clusterhead. After selecting clusterheads, affiliation of other nodes with the clusterhead is decided based on the quality of clusterhead, which is a function of connectivity, stability, residual battery power and transmission rate. Among the k dominating nodes, non clusterhead nodes select the most qualified node as its clusterhead. DSCAM creates stable clusters with less overhead and maximizes the life span of the network. The performance of this algorithm is evaluated through simulation and the results are encouraging. View full abstract»

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  • Joint Hierarchical Nodes Based User Management (JoHNUM) Infrastructure for the Development of Scalable and Consistent Virtual Worlds

    Page(s): 105 - 112
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (331 KB) |  | HTML iconHTML  

    Virtual environments (VEs) have recently gained a lot of attention from the computing, graphics, business and social communities due to a remarkable increase in their popularity. These communities are working together to make these environments more sociable and interesting while introducing novel applications. A number of technical infrastructures are currently hosting these environments, however, client multi server (CMS) infrastructures are considered best for their flexibility. Scalability and consistency are basic issues in developing large scale distributed virtual environments (DVEs) that require special attention. The existing mechanisms have major performance issues, and therefore, more sophisticated infrastructures are required to deal with dynamic requirements of the applications. In this paper, we propose a novel joint hierarchical nodes based user management (JoHNUM) infrastructure for the development of scalable and consistent virtual worlds. It is compared with the game middleware, Matrix, for evaluation purposes that has demonstrated better performance over the existing static mechanisms. Simulation results show that JoHNUM achieves lower levels resource management tree (RMT) and increases user interactive experience. Moreover, it uses fewer resources and minimizes communication overhead, almost the same as Matrix. View full abstract»

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  • DCS: A Distributed Coordinate System for Network Positioning

    Page(s): 113 - 120
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (492 KB) |  | HTML iconHTML  

    Predicting latency between nodes on the Internet can have a significant impact on the performance of many services that use latency distances among nodes as a decision making input. Coordinate-based approaches are among the family of latency prediction techniques where latency between each pair of nodes is modeled as the virtual distance among those nodes over a virtual system. This article proposes the decentralized coordinate system (DCS) as a fully distributed system that does not rely on any infrastructure support from the underlying network. DCS uses a two-phase algorithm: first, each host is assigned rough coordinates, then, the rough estimation is refined in a way that it gradually converges to the accurate relative position of nodes. Simulation results demonstrate that the accuracy of DCS is competitive with existing network coordinate systems and that it can be considered as a good alternative for some applications. View full abstract»

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