The High Level Architecture (HLA) provides the specification of a software architecture for distributedsimulation. The baseline definition of the HLA includes the HLA Rules, The HLA Interface Specification, and the H...
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The High Level Architecture (HLA) provides the specification of a software architecture for distributedsimulation. The baseline definition of the HLA includes the HLA Rules, The HLA Interface Specification, and the HLA Object Model Template. The HLA Rules are a set of 10 basic rules that define the responsibilities and relationships among the components of an HLA federation. The HLA Interface Specification provides a specification of the functional interfaces between HLA federates and the HLA Runtime Infrastructure. The HLA OMT provides a common presentation format for HLA simulation and Federation Object Models. The HLA was developed over the past three years. It is currently in the process of being applied with simulations developed for analysis, training and test and evaluation and incorporated into industry standards for distributedsimulation by both the Object Management Group and the IEEE. This paper provides a discussion of key areas where there are technology challenges in the future implementation and application of the HLA.
In this paper, we present a parallel simulator (SWiMNet) for PCS networks using a combination of optimistic and conservative paradigms. The proposed methodology exploits event precomputation permitted by model indepen...
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In this paper, we present a parallel simulator (SWiMNet) for PCS networks using a combination of optimistic and conservative paradigms. The proposed methodology exploits event precomputation permitted by model independence within the PCS components. The low percentage of blocked calls is exploited in the channel allocation simulation of precomputed events by means of an optimistic approach. Experiments were conducted with various call arrival rates and mobile host densities on a cluster of Pentium workstations. Performance results indicate that the SWiMNet achieves a speedup of 6 employing 8 workstations, and a speedup of 12 with 16 workstations.
Environment aware, self adaptive Time Warp logical processes (LPs) implementing a pro-active performance control scheme, thus addressing the timeliness of control decisions, are introduced. The ability of these pro-ac...
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Environment aware, self adaptive Time Warp logical processes (LPs) implementing a pro-active performance control scheme, thus addressing the timeliness of control decisions, are introduced. The ability of these pro-active TW LPs to adapt to sudden load changes is examined. Experimental results show that the protocol is able to capture abrupt changes in both computational and communication resource availability.
The performance of parallel discrete event simulation protocols is heavily dependent on the lookahead of the simulation model. Identifying and expressing correct lookahead for a model isn't easy, nor is it a well-...
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The performance of parallel discrete event simulation protocols is heavily dependent on the lookahead of the simulation model. Identifying and expressing correct lookahead for a model isn't easy, nor is it a well-defined process. In this paper, a global view of a PDES model as a set of data flows is presented. Using this view, we show how the lookahead of the model can be optimized, and we present various simplified implementations of this global view and the significant performance improvements generated when applied to real world models.
We present two GVT computation algorithms for PDES techniques with event based activities, and relying on a space-time memory abstraction. Algorithm 2 involves a modification in the activity control, and is based on a...
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We present two GVT computation algorithms for PDES techniques with event based activities, and relying on a space-time memory abstraction. Algorithm 2 involves a modification in the activity control, and is based on an epoch coloring scheme. The effect of the modification is assessed through an experimental study on a simulator implemented in the Linda coordination language. Experiments are performed on a cluster of workstations, and show that the modified activity control discipline is able to enhance performances.
This paper describes a new, auto-adaptive algorithm for dead reckoning in DIS. In general dead-reckoning algorithms use a fixed threshold to control the extrapolation errors. Since a fixed threshold cannot adequately ...
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ISBN:
(纸本)9780769501550
This paper describes a new, auto-adaptive algorithm for dead reckoning in DIS. In general dead-reckoning algorithms use a fixed threshold to control the extrapolation errors. Since a fixed threshold cannot adequately handle the dynamic relationships between moving entities, a multi-level threshold scheme is proposed. The definition of threshold levels is based on the concepts of area of interest (AOI) and sensitive region (SR), and the levels of threshold are adaptively adjusted based on the relative distance between entities during the simulation. Various experiments were conducted. The results show that the proposed auto-adaptive dead reckoning algorithm can achieve considerable reduction in update packets without sacrificing accuracy in extrapolation.
This paper describes a new, auto-adaptive algorithm for dead reckoning in DIS. In general dead-reckoning algorithms use a fixed threshold to control the extrapolation errors. Since a fixed threshold cannot adequately ...
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This paper describes a new, auto-adaptive algorithm for dead reckoning in DIS. In general dead-reckoning algorithms use a fixed threshold to control the extrapolation errors. Since a fixed threshold cannot adequately handle the dynamic relationships between moving entities, a multi-level threshold scheme is proposed. The definition of threshold levels is based on the concepts of area of interest (AOI) and sensitive region (SR), and the levels of threshold are adaptively adjusted based on the relative distance between entities during the simulation. Various experiments were conducted. The results show that the proposed auto-adaptive dead reckoning algorithm can achieve considerable reduction in update packets without sacrificing accuracy in extrapolation.
This paper presents a checkpointing scheme for optimistic simulation which is a mixed approach between periodic and probabilistic checkpointing. The latter, basing on statistical data collected during the simulation, ...
ISBN:
(纸本)9780769501550
This paper presents a checkpointing scheme for optimistic simulation which is a mixed approach between periodic and probabilistic checkpointing. The latter, basing on statistical data collected during the simulation, aims at recording as checkpoints states of a logical process that have high probability to be restored due to rollback (this is done in order to make those states immediately available). The periodic part prevents performance degradation due to state reconstruction (coasting forward) cost whenever the collected statistics do not allow to identify states highly likely to be ***, this scheme can be seen as a highly general solution to tackle the checkpoint problem in optimistic simulation. A performance comparison with previous solutions is carried out through a simulation study of a store-and-forward communication network in a two-dimensional torus topology.
This paper presents the SEEDS simulation environment for the evaluation of distributed traffic control systems. Starting with an overview of the general simulator architecture, the software modules and the derived har...
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This paper presents the SEEDS simulation environment for the evaluation of distributed traffic control systems. Starting with an overview of the general simulator architecture, the software modules and the derived hardware architecture of the simulation environment are described with respect to performance requirements. The communication architecture of the SEEDS simulator is based on the OMG's CORBA standard and the DIS simulation protocol. With the SEEDS prototype simulating airport ground-traffic, performance measurements evaluating critical design and implementation decisions are described. The main aspects of the performance analysis are the attained application performance using CORBA and DIS as communication middle-ware, and the scalability of the overall approach. The evaluation shows the appropriateness of the design of the simulation environment and the derived hard- and software architecture, which is flexible and open to further extensions. Moreover, the combination of CORBA and DIS provides a suited platform for distributed interactive simulation purposes because of the adequate performance, high scalability, and the high-level programming model which allows to rapidly develop and maintain complex distributed applications with high-performance requirements.
Ordering of simultaneous events in DES is an important issue as it has an impact on modelling expressiveness, model correctness as well as causal dependencies. In sequential DES this is a problem which has attracted m...
ISBN:
(纸本)9780769501550
Ordering of simultaneous events in DES is an important issue as it has an impact on modelling expressiveness, model correctness as well as causal dependencies. In sequential DES this is a problem which has attracted much attention over the years and most systems provide the user with tools to deal with such issues. This has also attracted some attention within the PDES community and we present an overview of these efforts. We have, however, not yet found a scheme which provides us with the desired functionality. Thus, we present and evaluate some simple schemes to achieve a well defined ordering of events and means to identify both causally dependent and independent events with identical timestamps in the context of optimistic simulations. These schemes should be applicable also to conservative PDES.
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