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4th International Conference on parallel Computing Technologies, PaCT 1997

作者： Dietz, R.D. Casavant, T.L. Scheetz, T.E. Braun, T.A. Andersland, M.S. Parallel Processing Laboratory Electrical and Computer Engineering Department The University of Iowa Iowa CityIA52242 United States

ISBN: (纸本)3540633715

Increasingly, feedback of measured run-time information is being used in the optimization of computation execution. Because of this, the need for a model relating the static view of a computation to its runtime variance is becoming more important. Recently, we have described such a model which uses the notion of uncertainty to provide bounds on key scheduling parameters of the run-time computation. In this paper, we demonstrate how our model provides a foundation for robust parallel scheduling, i.e., scheduling that optimizes for computation execution in the presence of run-time variance. While this work was inspired by our previous study of uncertainty due to measurement intrusion, the scheduling paradigm presented here represents a broader, more general application of the uncertainty concept. © Springer-Verlag Berlin Heidelberg 1997.

关键词： Scheduling

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A stochastic model of a dedicated heterogeneous computing system for establishing a greedy approach to developing data relocation heuristics

A stochastic model of a dedicated heterogeneous computing sy...

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Heterogeneous Computing Workshop

作者： Min Tan H.J. Siegel Parallel Processing Laboratory School of Electrical and Computer Engineering Purdue University West Lafayette IN USA

In a dedicated mixed-machine heterogeneous computing (HC) system, an application program may be decomposed into subtasks, then each subtask assigned to the machine where it is best suited for execution. Subtask data relocation is defined as selecting the sources for their needed data items. This study focuses on theoretical issues for data relocation using a stochastic HC model. It is assumed that multiple independent subtasks of an application program can be executed concurrently on different machines whenever possible. A stochastic model for HC is proposed, in which the computation times of subtasks and communication times for inter-machine data transfers can be random variables. The optimization problem for finding the optimal matching, scheduling, and data relocation schemes to minimize the total execution time of an application program is defined based on this stochastic HC model. The optimization criteria and search space for the above optimization problem are described. It is proven that a greedy algorithm based approach will generate the optimal data relocation scheme with respect to any fixed matching and scheduling schemes. This result indicates that a greedy algorithm based approach is the best strategy for developing data relocation heuristics in practice.

关键词： Stochastic systems Stochastic processes Processor scheduling Application software Greedy algorithms Random variables Optimal matching computer networks parallel processing Laboratories

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Background compensation and an active-camera motion tracking algorithm

Background compensation and an active-camera motion tracking...

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International Conference on parallel processing (ICPP)

作者： R. Gupta M.D. Theys H.J. Siegel Parallel Processing Laboratory School of Electrical and Computer Engineering Purdue University West Lafayette IN USA

Motion tracking using an active camera is a very computationally complex problem. Existing serial algorithms have provided frame rates that are much lower than those desired, mainly because of the lack of computational resources. parallel computers are well suited to image processing tasks and can provide the computational power that is required for real-time motion tracking algorithms. This paper develops a parallel implementation of a known serial motion tracking algorithm, with the goal of achieving greater than real-time frame rates, and to study the effects of data layout, choice of parallel mode of execution, and machine size on the execution time of this algorithm. A distinguishing feature of this application study is that the portion of each image frame that is relevant changes from one frame to the next based on the camera motion. This impacts the effect of the chosen data layout on the needed inter-processor data transfers and the way in which work is distributed among the processors. Experiments were performed to determine for which image sizes and number of processors which data layout would perform better. The parallel computers used in this study are the MasPar MP-1, Intel Paragon, and PASM. Different modes are examined and it is determined that mixed mode is faster than SIMD or MIMD implementations.

关键词： Cameras Target tracking Concurrent computing parallel processing Laboratories Power engineering computing Contracts Image processing Hardware parallel machines

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Modeling the impact of run-time uncertainty on optimal computation scheduling using feedback

Modeling the impact of run-time uncertainty on optimal compu...

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International Conference on parallel processing (ICPP)

作者： R.D. Dietz T.L. Casavant T.E. Scheetz T.A. Braun M.S. Andersland Parallel Processing Laboratory Electrical and Computer Engineering Department University of Iowa IA USA

Increasingly, feedback of measured run-time information is being used in the optimization of computation execution. This paper introduces a model relating the static view of a computation to its run-time variance that is useful in this context. A notion of uncertainty is then used to provide bounds on key scheduling parameters of the run-time computation. To illustrate the relationship between fidelity in measured information and minimum schedulable, grain size, we apply the bounds to three existing parallel architectures for the case of run-time variance caused by monitoring intrusion. We also outline a hybrid static-dynamic scheduling paradigm-SEDIA-that uses the model of uncertainty to optimize computation for execution in the presence of run-time variance from sources other than monitoring intrusion.

关键词： Runtime Uncertainty Processor scheduling Feedback Context modeling Optimal scheduling Dynamic scheduling Concurrent computing Monitoring Delay

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On-line use of off-line derived mappings for iterative automatic target recognition tasks and a particular class of hardware platforms

On-line use of off-line derived mappings for iterative autom...

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Heterogeneous Computing Workshop

作者： J.R. Budenske R.S. Ramanujan H.J. Siegel Architecture Technology Corporation Minneapolis MN USA Parallel Processing Laboratory School of Electrical and Computer Engineering Purdue University West Lafayette IN USA

Heterogeneous computing covers a great variety of situations. This study focuses on a particular application domain (iterative automatic target recognition tasks) and an associated specific class of dedicated heterogeneous hardware platforms. The contribution of this paper is that, for the computational environment considered, it presents a methodology for real-time on-line input-data dependent remappings of the application subtasks to the processors in the heterogeneous hardware platform using previously stored off-line statically determined mappings. That is, the operating system will be able to decide during the execution of the application whether or not to perform a remapping based on information generated by the application from its input data. If the decision is to remap, the operating system will be able to select a previously derived and stored mapping that is appropriate for the given state of the application (e.g., the number of objects it is currently tracking).

关键词： Target recognition Kernel Hardware Operating systems Concurrent computing Distributed computing computer architecture parallel processing Laboratories Military computing

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Color image compression using an embedded rate scalable approach

Color image compression using an embedded rate scalable appr...

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IEEE International Conference on Image processing

作者： K. Shen E.J. Delp Video and Image Processing Laboratory School of Electrical and Computer Engineering Purdue University West Lafayette IN USA

In this paper we propose a wavelet based coding algorithm for color images using a luminance/chrominance color space. Data rate scalability is achieved by using an embedded coding scheme, which is similar to Shapiro's (1993) embedded zerotree wavelet (EZW) algorithm. In a luminance/chrominance color space, the three color components have little statistical correlation. However, observations are made that at the spatial locations where chrominance signals have large transitions, it is highly likely for the luminance signal to have large transitions. This interdependence between the color components is exploited in the algorithm.

关键词： Color Image coding Pixel Streaming media Scalability Wavelet transforms Video compression Image processing Laboratories Embedded computing

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Multiresolution detection of stellate lesions in mammograms

Multiresolution detection of stellate lesions in mammograms

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IEEE International Conference on Image processing

作者： Sheng Liu E.J. Delp Video and Image Processing Laboratory VIPER School of Electrical and Computer Engineering Purdue University West Lafayette IN USA

Presents a new multiresolution scheme for the detection of stellate lesions in digital mammograms. First, a multiresolution representation of the original mammogram is obtained using a linear phase nonseparable 2-D wavelet transform. A set of features are then extracted at each resolution for every pixel. This addresses the difficulty of predetermining the neighborhood size for feature extraction to characterize objects that may appear with different sizes. Detection is performed from the coarsest resolution to the finest resolution using binary tree classifiers. This top-down approach requires less computation by starting with the least amount of data and propagating detection results to finer resolutions. Experimental results on the MIAS image database have shown that this algorithm is capable of detecting stellate lesions of very different sizes.

关键词： Lesions Feature extraction Wavelet transforms Binary trees Classification tree analysis Image databases

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A fast suboptimal approach to error concealment in encoded video streams

A fast suboptimal approach to error concealment in encoded v...

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IEEE International Conference on Image processing

作者： P. Salama N. Shroff E.J. Delp Video and Image Processing Laboratory VIPER School of Electrical and Computer Engineering Purdue University West Lafayette IN USA

In ATM networks cell loss or channel errors can cause data to be dropped in the channel. When digital video is transmitted over these networks one must be able to reconstruct the missing data so that the impact of these errors is minimized. In this paper we describe a Bayesian approach to concealing these errors by post-processing the received data. In a previous paper (see IEEE Proc. Int. Conf. on Image processing p.49-52, 1996), each frame in the sequence was modeled as a Markov random field, and maximum a posteriori estimates of the missing macroblocks were obtained. However, the maximum a posteriori estimate is not unique, and the algorithm is also computationally intensive. In this paper we demonstrate, that by using median filtering we arrive at a suboptimal estimate. This will allow real-time nearly optimal reconstruction of the missing data.

关键词： Image reconstruction Maximum a posteriori estimation Bayesian methods Image processing Markov random fields Filtering

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Combined modulation and error correction codes for storage channels

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IEEE TRANSACTIONS ON MAGNETICS 1996年第2期32卷 509-514页

作者： Lee, JJ Madisetti, VK Digital Signal Processing Laboratory School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta CA USA

Multitrack codes that have recently been proposed for the magnetic storage channel promise larger capacities than conventional run-length limited (RLL) single-track codes. This paper proposes an approach that combines modulation and error-correcting capabilities with resilience to intertrack interference (ITI) in the magnetic storage channel with constraints on the minimum run-length for each track, in conjunction with the minimum run-length constraint between tracks and the maximum run-length constraint satisfied by at least one track. Comparison is made with previously proposed approaches.

关键词： .capacities tracks error-correcting code rate modulation codes intertrack areal density Correction Codes Modulation and Error storage channel minimum run-length constraint

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Conditional entropy-constrained residual VQ with application to image coding

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IEEE TRANSACTIONS ON IMAGE processing 1996年第2期5卷 311-320页

作者： Kossentini, F Chung, WC Smith, MJT Digital Signal Processing Laboratory School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA USA

This paper introduces an extension of entropy-constrained residual vector quantization (VQ) where intervector dependencies are exploited, The method, which we call conditional entropy-constrained residual VQ, employs a high-order entropy conditioning strategy that captures local information in the neighboring vectors, When applied to coding images, the proposed method is shown to achieve better rate-distortion performance than that of entropy-constrained residual vector quantization with less computational complexity and lower memory requirements. Moreover, it can be designed to support progressive transmission in a natural way, It is also shown to outperform some of the best predictive and finite-state VQ techniques reported in the literature, This is due partly to the joint optimization between the residual vector quantizer and a high-order conditional entropy coder as well as the efficiency of the multistage residual VQ structure and the dynamic nature of the prediction.

关键词： image coding complexity classes progressive transmission entropy Vector quantization RESIDUAL memory requirements Conditional

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