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.
Distribution of data in mobile ad hoc networks is challenged when the mobility of nodes leads to frequent topology changes. Existing approaches so far address either the net-work partitioning problem or are capable of...
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ISBN:
(纸本)076951961X
Distribution of data in mobile ad hoc networks is challenged when the mobility of nodes leads to frequent topology changes. Existing approaches so far address either the net-work partitioning problem or are capable of handling large amounts of data, but not both at the same time. In this paper a novel approach is presented which is based on a negotiation scheme enhanced by an adaptive repetition strategy. Different strategies for the selection of repeated data are presented and evaluated. simulation results show a reduction of data transfer volume compared to hyper-flooding by 30 to 40% even in the presence of frequent network partitions.
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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Dynamic parallel Schedules (DPS) is a high-level framework for developing parallel applications on distributed memory computers (e.g. clusters of PCs). Its model relies on compositional customizable split-compute-merg...
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Dynamic parallel Schedules (DPS) is a high-level framework for developing parallel applications on distributed memory computers (e.g. clusters of PCs). Its model relies on compositional customizable split-compute-merge graphs of operations (directed acyclic flow graphs). The graphs and the mapping of operations to processing nodes are specified dynamically at runtime. DPS applications are pipelined and multithreaded by construction, ensuring a maximal overlap of computations and communications. DPS applications can call parallel services exposed by other DPS applications, enabling the creation of reusable parallel components. The DPS framework relies on a C++ class library. Thanks to its dynamic nature, DPS offers new perspectives for the creation and deployment of parallel applications running on server clusters.
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.
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.
The following topics are dealt with: high level architecture (HLA) and grid issues; real time systems; quality of service (QoS) and multimedia; parallel and distributedsimulation; methodology and Web-based simulation...
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The following topics are dealt with: high level architecture (HLA) and grid issues; real time systems; quality of service (QoS) and multimedia; parallel and distributedsimulation; methodology and Web-based simulation; distributedsimulation project management; and haptic audio visual collaborative virtual environments.
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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