L. Bononi, Michele Bracuto, Gabriele D’angelo, L. Donatiello
In this work we define and test a new framework obtained as the integration of two recently developed middlewares defined to support the parallel and distributed simulation of large scale, complex and dynamically interacting system models (like wireless and mobile network systems). In a distributed simulation of highly interacting system models, the main bottleneck may become the communication and synchronization required to maintain the causality constrains between distributed model components. We designed and implemented the ARTÌS middleware as a new framework incorporating a set of features that allow an adaptive optimization of the communication layer management in a distributed simulation scenario. ARTÌS has been integrated with GAIA, a dynamic mechanism for the runtime management and adaptive allocation of model entities in a distributed simulation. By adopting a runtime evaluation of causal bindings between model entities GAIA adapts the dynamic and time-persistent causal effects of model interactions to dynamic migration of model entities. Preliminary results demonstrate that the combined effect of ARTÌS management and GAIA heuristics leads to a significant reduction in the communication and synchronization overheads between the physical execution units. Simulation performance enhancements have been obtained also in worst-case modelling assumptions and simulation scenarios.
{"title":"A New Adaptive Middleware for Parallel and Distributed Simulation of Dynamically Interacting Systems","authors":"L. Bononi, Michele Bracuto, Gabriele D’angelo, L. Donatiello","doi":"10.1109/DS-RT.2004.3","DOIUrl":"https://doi.org/10.1109/DS-RT.2004.3","url":null,"abstract":"In this work we define and test a new framework obtained as the integration of two recently developed middlewares defined to support the parallel and distributed simulation of large scale, complex and dynamically interacting system models (like wireless and mobile network systems). In a distributed simulation of highly interacting system models, the main bottleneck may become the communication and synchronization required to maintain the causality constrains between distributed model components. We designed and implemented the ARTÌS middleware as a new framework incorporating a set of features that allow an adaptive optimization of the communication layer management in a distributed simulation scenario. ARTÌS has been integrated with GAIA, a dynamic mechanism for the runtime management and adaptive allocation of model entities in a distributed simulation. By adopting a runtime evaluation of causal bindings between model entities GAIA adapts the dynamic and time-persistent causal effects of model interactions to dynamic migration of model entities. Preliminary results demonstrate that the combined effect of ARTÌS management and GAIA heuristics leads to a significant reduction in the communication and synchronization overheads between the physical execution units. Simulation performance enhancements have been obtained also in worst-case modelling assumptions and simulation scenarios.","PeriodicalId":355772,"journal":{"name":"Eighth IEEE International Symposium on Distributed Simulation and Real-Time Applications","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127315251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The notion of spatial uncertainty indicates the lack of exact knowledge about where, within the simulated space, an event actually occurs. In one of our previous works, we have shown how to exploit spatial uncertainty to reduce the synchronization cost in optimistic simulation, in terms of amount of rollback. In this paper we show how to exploit spatial uncertainty also for reducing the expected cost of simulation events during forward computation, thus achieving further reduction of the wall-clock time for the simulation model execution. The application of this proposal to optimistic simulation of a Personal Communication System (PCS) is also presented, together with experimental results supporting the claim of increased execution speed of the simulation system.
{"title":"Exploiting Spatial Uncertainty to Reduce Forward Computation Cost in Optimistic Simulations","authors":"F. Quaglia, Andrea Santoro","doi":"10.1109/DS-RT.2004.19","DOIUrl":"https://doi.org/10.1109/DS-RT.2004.19","url":null,"abstract":"The notion of spatial uncertainty indicates the lack of exact knowledge about where, within the simulated space, an event actually occurs. In one of our previous works, we have shown how to exploit spatial uncertainty to reduce the synchronization cost in optimistic simulation, in terms of amount of rollback. In this paper we show how to exploit spatial uncertainty also for reducing the expected cost of simulation events during forward computation, thus achieving further reduction of the wall-clock time for the simulation model execution. The application of this proposal to optimistic simulation of a Personal Communication System (PCS) is also presented, together with experimental results supporting the claim of increased execution speed of the simulation system.","PeriodicalId":355772,"journal":{"name":"Eighth IEEE International Symposium on Distributed Simulation and Real-Time Applications","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124757096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Distributed simulation cloning technology is designed to analyze alternative scenarios of a distributed simulation concurrently within the same simulation execution session. One important goal of the technology is to optimize execution by avoiding repeated computation amongst independent scenarios. Our research is concerned with the cloning of High Level Architecture (HLA) based distributed simulations. A decoupled federate architecture is designed to support correct federate cloning at runtime. A federate may spawn clones to explore different scenarios at a decision point. To address the complexity of the overall cloning-enabled distributed simulation due to increasing scenario spawning, we have devised an efficient and precise scheme to identify and partition scenarios. It is desirable to use an incremental cloning mechanism to replicate only those federates whose states will be affected while the rest remain intact and are shared amongst the original and new scenarios. Our incremental cloning mechanism ensures accurate sharing and initiates cloning only when strictly necessary.
{"title":"HLA-Based Distributed Simulation Cloning","authors":"Dan Chen, S. Turner, Boon-Ping Gan, Wentong Cai","doi":"10.1109/DS-RT.2004.23","DOIUrl":"https://doi.org/10.1109/DS-RT.2004.23","url":null,"abstract":"Distributed simulation cloning technology is designed to analyze alternative scenarios of a distributed simulation concurrently within the same simulation execution session. One important goal of the technology is to optimize execution by avoiding repeated computation amongst independent scenarios. Our research is concerned with the cloning of High Level Architecture (HLA) based distributed simulations. A decoupled federate architecture is designed to support correct federate cloning at runtime. A federate may spawn clones to explore different scenarios at a decision point. To address the complexity of the overall cloning-enabled distributed simulation due to increasing scenario spawning, we have devised an efficient and precise scheme to identify and partition scenarios. It is desirable to use an incremental cloning mechanism to replicate only those federates whose states will be affected while the rest remain intact and are shared amongst the original and new scenarios. Our incremental cloning mechanism ensures accurate sharing and initiates cloning only when strictly necessary.","PeriodicalId":355772,"journal":{"name":"Eighth IEEE International Symposium on Distributed Simulation and Real-Time Applications","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127401444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaojun Shen, Jilin Zhou, Abdulmotaleb El Saddik, N. Georganas
A collaborative, haptic, audio and visual environment (C-HAVE) consists of a network of nodes. Each node in the C-HAVE world contributes to the shared environment with some virtual objects. These can be static, e.g., a sculpture or the ground, or dynamic, e.g., an object that can be virtually manipulated. We aim at developing a heterogeneous scalable architecture for large collaborative haptics environments where a number of potential users participate with different kinds of haptic devices. The main objective of the presented research is the development of three prototypes to demonstrate quantitatively the effects of adding haptics to a task. The experimental results reveal the effects of the different implementations on the performance and time delay of a particular task through objective measurement results.
{"title":"Architecture and Evaluation of Tele-Haptic Environments","authors":"Xiaojun Shen, Jilin Zhou, Abdulmotaleb El Saddik, N. Georganas","doi":"10.1109/DS-RT.2004.8","DOIUrl":"https://doi.org/10.1109/DS-RT.2004.8","url":null,"abstract":"A collaborative, haptic, audio and visual environment (C-HAVE) consists of a network of nodes. Each node in the C-HAVE world contributes to the shared environment with some virtual objects. These can be static, e.g., a sculpture or the ground, or dynamic, e.g., an object that can be virtually manipulated. We aim at developing a heterogeneous scalable architecture for large collaborative haptics environments where a number of potential users participate with different kinds of haptic devices. The main objective of the presented research is the development of three prototypes to demonstrate quantitatively the effects of adding haptics to a task. The experimental results reveal the effects of the different implementations on the performance and time delay of a particular task through objective measurement results.","PeriodicalId":355772,"journal":{"name":"Eighth IEEE International Symposium on Distributed Simulation and Real-Time Applications","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115406862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The network simulator ns-2 implements both wireless networks and emulation — a feature that allows to simulate a network environment among real stations. However, the real-time requirements of a network emulation introduce an inaccurate timing behavior of the simulator scheduler. These timing errors have a negative impact on the performance of network protocols in ns-2. Even more, they lead to false simulation results in the IEEE 802.11 protocol implementation. In this paper we present performance improvements in ns-2, that increase the accuracy of its virtual clock and the the exactness of the real-time simulation. Then we describe a simple time monitoring and correction technique that ensures a timely correct execution of network protocols and enables wireless network emulation in ns-2.
{"title":"Real-Time Network Emulation with ns-2","authors":"D. Mahrenholz, S. Ivanov","doi":"10.1109/DS-RT.2004.34","DOIUrl":"https://doi.org/10.1109/DS-RT.2004.34","url":null,"abstract":"The network simulator ns-2 implements both wireless networks and emulation — a feature that allows to simulate a network environment among real stations. However, the real-time requirements of a network emulation introduce an inaccurate timing behavior of the simulator scheduler. These timing errors have a negative impact on the performance of network protocols in ns-2. Even more, they lead to false simulation results in the IEEE 802.11 protocol implementation. In this paper we present performance improvements in ns-2, that increase the accuracy of its virtual clock and the the exactness of the real-time simulation. Then we describe a simple time monitoring and correction technique that ensures a timely correct execution of network protocols and enables wireless network emulation in ns-2.","PeriodicalId":355772,"journal":{"name":"Eighth IEEE International Symposium on Distributed Simulation and Real-Time Applications","volume":"191 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121986118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One of the known problems with shared object manipulation in virtual environments is the disruptive effect of network lag in collaboration sessions. Most solutions to this problem revolve around techniques to compensate for this lag at the network communication level. In this article, we examine a different approach: informing the user about the lag, using decorators, and allowing the user to react to it intuitively.
{"title":"Shared Object Manipulation with Decorators in Virtual Environments","authors":"S. Shirmohammadi, N. H. Woo","doi":"10.1109/DS-RT.2004.36","DOIUrl":"https://doi.org/10.1109/DS-RT.2004.36","url":null,"abstract":"One of the known problems with shared object manipulation in virtual environments is the disruptive effect of network lag in collaboration sessions. Most solutions to this problem revolve around techniques to compensate for this lag at the network communication level. In this article, we examine a different approach: informing the user about the lag, using decorators, and allowing the user to react to it intuitively.","PeriodicalId":355772,"journal":{"name":"Eighth IEEE International Symposium on Distributed Simulation and Real-Time Applications","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116788811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Katarzyna Rycerz, B. Baliś, R. Szymacha, M. Bubak, P. Sloot
In this paper we describe a Grid-enabled system for monitoring HLA-based applications to enable load balancing by migration of federates. The monitoring is based on the OCM-G system [2].We show how the design concepts of the OCM-G enable easy adaptation to monitoring of HLA, C++-based applications. The solution presented in this paper is transparent to the user application and does not require any changes to the original HLA RTI code. We also describe the role of monitoring the whole system for managing execution of HLA-based applications described in [25]. We discuss implementation issues and present test results for the monitoring overhead.
{"title":"Monitoring of HLA Grid Application Federates with OCM-G","authors":"Katarzyna Rycerz, B. Baliś, R. Szymacha, M. Bubak, P. Sloot","doi":"10.1109/DS-RT.2004.31","DOIUrl":"https://doi.org/10.1109/DS-RT.2004.31","url":null,"abstract":"In this paper we describe a Grid-enabled system for monitoring HLA-based applications to enable load balancing by migration of federates. The monitoring is based on the OCM-G system [2].We show how the design concepts of the OCM-G enable easy adaptation to monitoring of HLA, C++-based applications. The solution presented in this paper is transparent to the user application and does not require any changes to the original HLA RTI code. We also describe the role of monitoring the whole system for managing execution of HLA-based applications described in [25]. We discuss implementation issues and present test results for the monitoring overhead.","PeriodicalId":355772,"journal":{"name":"Eighth IEEE International Symposium on Distributed Simulation and Real-Time Applications","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125413098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Frécon, Olov Ståhl, J. Söderberg, Anders Wallberg
We describe a museum installation that explains the technical and mental process that sonar operators undergo when identifying underwater sounds in the surroundings of a submarine. The installation places the public in a cramped space composed of several coupled interactive stations offering different perspectives onto a virtual environment representing a part of the Baltic Sea. The virtual environment and its presentation within the installation are implemented as an application of the DIVE research toolkit. The installation has been on display in several museums on a daily basis for over a year. We describe the technical solutions that we have employed to realise the installation and some of our learning.
{"title":"Visualising Sound Perception in a Submarine: A Museum Installation","authors":"E. Frécon, Olov Ståhl, J. Söderberg, Anders Wallberg","doi":"10.1109/DS-RT.2004.43","DOIUrl":"https://doi.org/10.1109/DS-RT.2004.43","url":null,"abstract":"We describe a museum installation that explains the technical and mental process that sonar operators undergo when identifying underwater sounds in the surroundings of a submarine. The installation places the public in a cramped space composed of several coupled interactive stations offering different perspectives onto a virtual environment representing a part of the Baltic Sea. The virtual environment and its presentation within the installation are implemented as an application of the DIVE research toolkit. The installation has been on display in several museums on a daily basis for over a year. We describe the technical solutions that we have employed to realise the installation and some of our learning.","PeriodicalId":355772,"journal":{"name":"Eighth IEEE International Symposium on Distributed Simulation and Real-Time Applications","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121627671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Group communication in large-scale interactive applications such as real-time conferencing and collaboration, networked virtual environments (e.g. massively multi-player games) requires efficient, low-overhead group communication mechanisms. In this paper we consider the application-level (or end-system) multicast and propose a stateless group communication mechanism together with its tree building algorithms. Stateless multicast reduces the control signaling of dynamic multicast groups linearly with the group size. To support interactive applications involving a large number of dynamic multicast groups, the application level multicast uses stateless forwarding within clusters of network nodes and hierarchical aggregation of multicast group membership. We show that dynamic tree construction achieve low computation overhead with a controlled degradation of the end-to-end data path performance.
{"title":"Stateless Application-Level Multicast for Dynamic Group Communication","authors":"G. Popescu, Z. Liu","doi":"10.1109/DS-RT.2004.38","DOIUrl":"https://doi.org/10.1109/DS-RT.2004.38","url":null,"abstract":"Group communication in large-scale interactive applications such as real-time conferencing and collaboration, networked virtual environments (e.g. massively multi-player games) requires efficient, low-overhead group communication mechanisms. In this paper we consider the application-level (or end-system) multicast and propose a stateless group communication mechanism together with its tree building algorithms. Stateless multicast reduces the control signaling of dynamic multicast groups linearly with the group size. To support interactive applications involving a large number of dynamic multicast groups, the application level multicast uses stateless forwarding within clusters of network nodes and hierarchical aggregation of multicast group membership. We show that dynamic tree construction achieve low computation overhead with a controlled degradation of the end-to-end data path performance.","PeriodicalId":355772,"journal":{"name":"Eighth IEEE International Symposium on Distributed Simulation and Real-Time Applications","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131827644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper outlines the development of a virtual environment for constraint based assembly and maintenance task simulation and analysis of large scale mechanical products. It is important that allowance is made for maintenance activities during a products design phase to help reduce the lifetime operating costs of such large scale mechanical products. Unfortunately, current CAE systems do not support such assessment capabilities, with these issues typically being addressed using expensive and time consuming physical prototypes. The design and implementation of an immersive virtual prototyping environment for supporting the assessment of assemblability and maintainability of large scale mechanical products, along with its use as a maintenance training tool will be outlined. Procedures and environments for realistic component assembly, constraint recognition, automatic disassembly sequence generation, and maintenance review and training are presented. The simulation of maintenance operations allows for maintenance to be addressed early in the design stages. This reduces unforeseen problems creeping into the design as it progresses through its life cycle, consequently saving both time and money while improving product quality.
{"title":"An Immersive Assembly and Maintenance Simulation Environment","authors":"Norman Murray, T. Fernando","doi":"10.1109/DS-RT.2004.7","DOIUrl":"https://doi.org/10.1109/DS-RT.2004.7","url":null,"abstract":"This paper outlines the development of a virtual environment for constraint based assembly and maintenance task simulation and analysis of large scale mechanical products. It is important that allowance is made for maintenance activities during a products design phase to help reduce the lifetime operating costs of such large scale mechanical products. Unfortunately, current CAE systems do not support such assessment capabilities, with these issues typically being addressed using expensive and time consuming physical prototypes. The design and implementation of an immersive virtual prototyping environment for supporting the assessment of assemblability and maintainability of large scale mechanical products, along with its use as a maintenance training tool will be outlined. Procedures and environments for realistic component assembly, constraint recognition, automatic disassembly sequence generation, and maintenance review and training are presented. The simulation of maintenance operations allows for maintenance to be addressed early in the design stages. This reduces unforeseen problems creeping into the design as it progresses through its life cycle, consequently saving both time and money while improving product quality.","PeriodicalId":355772,"journal":{"name":"Eighth IEEE International Symposium on Distributed Simulation and Real-Time Applications","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123089874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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