We propose a new iterative distributed estimation algorithm for Gaussian hidden Markov graphical models with loops. We decompose a loopy graph into a number of linked embedded triangles and then apply a parallel block...
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ISBN:
(纸本)0780379977
We propose a new iterative distributed estimation algorithm for Gaussian hidden Markov graphical models with loops. We decompose a loopy graph into a number of linked embedded triangles and then apply a parallel block-Jacobi iteration comprising local linear minimum mean-square-error estimation on each triangle (involving a simple 3 x 3 matrix inverse computation) followed by an information exchange between neighboring nodes and triangles. A simulation study demonstrates that the algorithm converges extremely rapidly, outperforming a number of existing algorithms. Embedded triangles are simple, local, scalable, fault-tolerant, and energy-efficient, and thus ideally suited for wireless sensor networks.
Internet data traffic is doubling each year, yet bandwidth does not appear to be growing as fast as expected and thus short falls in available bandwidth, particularly at the "last mile" may result. To addres...
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distributedsimulation enables participants situated in different geographical locations to share a common virtual world, which is called a distributed virtual environment (DVE). Among the different research topics co...
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ISBN:
(纸本)9780769520360
distributedsimulation enables participants situated in different geographical locations to share a common virtual world, which is called a distributed virtual environment (DVE). Among the different research topics concerned with DVE, there is a current trend of linking multi-agent systems and DVE together. With the properties of autonomy, social ability, reactivity and proactiveness, agents can be used to represent entities in DVE, where fast and accurate decision making is a determining factor of the whole environment. This paper provides a description of integrating agents into an HLA-based distributedsimulation. It focuses on how to construct the sensor of an agent with different interest management schemes. Using the JADE (Java agent development framework) agent toolkit and the high level architecture (HLA) in our prototype, a minesweeping game, we outline two different implementations of this game. Due to the dynamic characteristics of agents, a problem of overdue information from the environment is discussed, and we propose an enlarged subscription region method to solve this problem. Moreover, advisories provided by the HLA are adopted to reduce the overheads. Conclusions are drawn based on the experimental results of these implementations.
The following topics are dealt with: NLP (natural language processing) technologies for MLIM (multi-lingual information management); system issues in MLIM; and multilingual text processing.
The following topics are dealt with: NLP (natural language processing) technologies for MLIM (multi-lingual information management); system issues in MLIM; and multilingual text processing.
As new technologies become available we need to identify their potential for application. In some cases new technologies are developed in response to specific needs (demand led), in others the technologies are develop...
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ISBN:
(纸本)9780769520360
As new technologies become available we need to identify their potential for application. In some cases new technologies are developed in response to specific needs (demand led), in others the technologies are developed and suitable applications are then sought (technology led). In this paper, the potential for applying distributedsimulation is discussed. Three modes of simulation practice are described: software engineering; process of organizational change; and facilitation. The ways in which distributedsimulation might aid these modes of practice are identified as well as some of the difficulties in adopting distributedsimulation. The extent to which distributedsimulation is an example of a demand led or a technology led innovation is also discussed. The emphasis is particularly on the practice of simulation in business, where distributedsimulation has to date had little impact.
Time-parallelsimulation defines a methodology that can be applied to certain specific simulation problems. We present a time-parallel approach for trace-driven simulation of the CSMA/CD protocol. The "memoryless...
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ISBN:
(纸本)9780769519708
Time-parallelsimulation defines a methodology that can be applied to certain specific simulation problems. We present a time-parallel approach for trace-driven simulation of the CSMA/CD protocol. The "memoryless" property of the physical system under moderate traffic loads allows for efficient time-parallelsimulation. We also present two optimization techniques: the estimation of idle points and the incremental fix-up computation. The former can improve the probability that a subtrace begins with a known initial system state. The latter can speedup the fix-up computation that is required when the estimation of the initial state is incorrect.
In this paper, we propose a design methodology for fault tolerant adaptive routers for parallel and distributed computers. The key idea of our method is integrating minimal and non-minimal routing that is supported by...
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ISBN:
(纸本)0769520197
In this paper, we propose a design methodology for fault tolerant adaptive routers for parallel and distributed computers. The key idea of our method is integrating minimal and non-minimal routing that is supported by independent virtual channels (VCs). Distinguishing the routing functions for each set of VCs simplifies the design of fault-tolerant algorithms. After describing the method, we show an application of a routing algorithm for two-dimensional mesh and torus networks. This algorithm, called Detour-NF, supports three routing modes: deterministic, minimal fully adaptive and non-minimal fault-tolerant operations. We also discuss the hardware cost and operational speed of minimal and non-minimal routers based on our design, which uses hardware description language (HDL). Communication performance and fault-tolerance are demonstrated by an HDL simulation. The experimental results show that supporting both minimal and non-minimal routing modes is advantageous for high-bandwidth and low-latency communication, as well as fault-tolerance.
Large-scale parallel discrete event simulations of massive networks, such as the Internet, are "Grand Challenge" problems: packet level simulation of even a small fraction of the Internet would consume the r...
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ISBN:
(纸本)9780769519708
Large-scale parallel discrete event simulations of massive networks, such as the Internet, are "Grand Challenge" problems: packet level simulation of even a small fraction of the Internet would consume the resources of the most powerful computers available. We reimplement the SSF scalable simulation framework so we can run large-scale network simulations originally written for DaSSF. Our implementation, CraySSF, is designed for the Cray-MTA, a multithreaded supercomputer architecture developed specifically to address large-scale computations of the kind that are not easily distributed. We describe the architecture, implementation issues, and preliminary performance results on a variety of (stock) serial and parallel architectures.
We introduce a technique to control the overhead of time management processes in order to make such mechanisms appropriate for real-time distributedsimulation is introduced. A novel message accounting scheme, the off...
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ISBN:
(纸本)9780769519708
We introduce a technique to control the overhead of time management processes in order to make such mechanisms appropriate for real-time distributedsimulation is introduced. A novel message accounting scheme, the offset-epoch method, is presented as a way to increase the efficiency of time management algorithms by eliminating transient messages. A synchronized lower-bound on timestamp (LBTS) computation exploits this efficiency to reduce time management overheads. This approach represents one step in bridging the gap that now exists between analytic and real-time distributedsimulations.
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