simulation replication is a necessity for all stochastic simulations. Its efficient execution is particularly important when additional techniques are used on top, such as optimization or sensitivity analysis. One way...
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ISBN:
(纸本)9780769537139
simulation replication is a necessity for all stochastic simulations. Its efficient execution is particularly important when additional techniques are used on top, such as optimization or sensitivity analysis. One way to improve replication efficiency is to ensure that the best configuration of the simulation system is used for execution. A selection of the best configuration is possible when the number of required replications is sufficiently high, even without any prior knowledge on simulator performance or problem instance. We present an adaptive replication mechanism that combines portfolio theory with reinforcement learning: it adapts itself to the given problem instance at runtime and can be restricted to an efficient algorithm portfolio.
The application of parallel and distributedsimulation techniques is often limited by the amount of parallelism available in the model. This holds true for large-scale cell-biological simulations, afield that has emer...
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ISBN:
(纸本)9780769531595
The application of parallel and distributedsimulation techniques is often limited by the amount of parallelism available in the model. This holds true for large-scale cell-biological simulations, afield that has emerged as data and knowledge concerning these systems increases and biologists call for tools to guide wet-lab experimentation. A promising approach to exploit parallelism in this domain is the integration of spatial aspects, which are often crucial to a model's validity. We describe an optimistic, parallel and distributed variant of the Next-Subvolume Method (NSM), a method that augments the well-known Gillespie Stochastic simulation Algorithm (SSA) with spatial features. We discuss requirements imposed by this application on a parallel discrete event simulation engine to achieve efficient execution. First results of combining NSM and the grid-inspired simulation system AURORA are shown.
Vehicular traffic simulations are useful in applications such as emergency management and homeland security planning tools. High speed of traffic simulations translates directly to speed of response and level of resil...
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ISBN:
(纸本)9780769531595
Vehicular traffic simulations are useful in applications such as emergency management and homeland security planning tools. High speed of traffic simulations translates directly to speed of response and level of resilience in those applications. Here, a parallel traffic simulation approach is presented that is aimed at reducing the time for simulating emergency vehicular traffic scenarios. Three unique aspects of this effort are: (1) exploration of optimistic simulation applied to vehicular traffic simulation (2) addressing reverse computation challenges speck to optimistic vehicular traffic simulation (3) achieving absolute (as opposed to self-relative) speedup with a sequential speed equal to that of a fast, de facto standard sequential simulator for emergency traffic. The design and development of the parallelsimulation system is presented, along with a performance study that demonstrates excellent sequential performance as well as parallel performance.
We adapt a scalable layered intelligence technique from the game industry, for agent-based crowd simulation. We extend this approach for planned movements, pursuance of assignable goals, and avoidance of dynamically i...
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ISBN:
(纸本)9780769531595
We adapt a scalable layered intelligence technique from the game industry, for agent-based crowd simulation. We extend this approach for planned movements, pursuance of assignable goals, and avoidance of dynamically introduced obstacles/threats, while keeping the system scalable with the number of agents. We exploit parallel processing for expediting the pre-processing step that generates the path-plans offline. We demonstrate the various behaviors in a hall-evacuation scenario, and experimentally establish the scalability of the frame-rates with increasing number of agents.
The modelling and simulation of autonomous pedestrians has important applications in real-time crowd and crisis simulations. With the increase in processing powers and dedicated graphics cards, more processing powers ...
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ISBN:
(纸本)9780769531595
The modelling and simulation of autonomous pedestrians has important applications in real-time crowd and crisis simulations. With the increase in processing powers and dedicated graphics cards, more processing powers can now be allocated for the generation of realistic behaviours for individuals within the crowd. We have proposed a representation for autonomous agents that is aimed to generate some human-like behaviours. In particular, to generate smooth and realistic navigational behaviour such as human-like collision avoidance, we have also proposed a two tier navigation model for autonomous agents. Using the proposed model, a scene in a typical shopping mall has been created. Behaviours such as crowd avoidance and lane following have been observed from the simulation.
We propose a new simulation method, called interval branching, which aims to facilitate efficient simulation studies of systems that involve temporal uncertainty. The method uses interval timestamps for events and exp...
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ISBN:
(纸本)9780769531595
We propose a new simulation method, called interval branching, which aims to facilitate efficient simulation studies of systems that involve temporal uncertainty. The method uses interval timestamps for events and explores different execution orders of overlapping events by branching the simulation. We first present a sequential version of interval branching, and then extend it to parallelsimulation using the logical process paradigm. The parallel interval branching algorithm uses the logical-process cloning technique for efficient computation of branches. Our preliminary experiments show its potential as an efficient method for discrete-event simulation studies.
Lookahead is a critical factor in conservative parallelsimulation. Greater lookahead usually brings better performance. However, in the simulation of computer networks, lookahead is usually determined by the minimal ...
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ISBN:
(纸本)9780769531595
Lookahead is a critical factor in conservative parallelsimulation. Greater lookahead usually brings better performance. However, in the simulation of computer networks, lookahead is usually determined by the minimal delay of the border links between any two subnets that simulated by different sequential logical processes (LPs), which is too small to get good performance. Traditionally, the lookahead exploitation usually only reflects the parallelism among LPs, which possibly wastes the potential parallelism inside each LP, especially, in the case that each LP simulates thousands of entities. Here we present a simple method called micro-synchronization to exploit the parallelism inside each LP. Different from the previous work, such as lookahead accumulation and local time warp, we keep the traditional usage of lookahead among LPs unchanged, and however, we impose the relaxed sequential event scheduling inside each LP, which can indirectly improve the lookahead We also present a state causality model to prove the correctness of our method, which means that there is no risk in the relaxed sequential execution. Finally, the experiment evaluates our method and shows that it can improve the performance of conservative parallelsimulation of computer networks to some extent.
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