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International Symposium on parallel and distributed processing with Applications, ISPA

作者： Rabindra Bista Young-Sung Shin Jae-Woo Chang Department of Computer Engineering and Center of Advanced Image and Information Technology Chonbuk National University of Korea Cheongju Chungbuk South Korea

In this paper, we propose a new privacy preserving data aggregation scheme for WSNs. Our scheme applies additive property of complex numbers in order to combine sensor data and preserve data privacy during transmission to the sink node. In addition, for supporting scalability, we propose a novel mechanism in which a special set of real numbers are assigned to sensor nodes as their IDs so that a single bit is sufficient to hold ID of a sensor node during transmission of aggregated data to the sink node. For this, we, first, generate fixed size signatures for the IDs of all sensor nodes and then superimpose the signatures during data aggregation phase. By analytical evaluations, we show that our scheme is more scalable and energy efficient than the existing methods to achieve data privacy and transmit IDs of sensor nodes along with the aggregated data to the sink node.

关键词： Wireless sensor networks Data privacy Payloads Technical Activities Guide - TAG Encryption Tin Aggregates

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On the parallelisation of MCMC by speculative chain execution

On the parallelisation of MCMC by speculative chain executio...

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IEEE International Symposium on parallel and distributed processing Workshops and Phd Forum (IPDPSW)

作者： Jonathan M. R. Byrd Stephen A. Jarvis Abhir H. Bhalerao Department of Computer Science University of Warwick Coventry UK

ISBN: (纸本)9781424465330

The increasing availability of multi-core and multiprocessor architectures provides new opportunities for improving the performance of many computer simulations. Markov Chain Monte Carlo (MCMC) simulations are widely used for approximate counting problems, Bayesian inference and as a means for estimating very high-dimensional integrals. As such MCMC has had a wide variety of applications in fields including computational biology and physics, financial econometrics, machine learning and image processing. One method for improving the performance of Markov Chain Monte Carlo simulations is to use SMP machines to perform 'speculative moves', reducing the runtime whilst producing statistically identical results to conventional sequential implementations. In this paper we examine the circumstances under which the original speculative moves method performs poorly, and consider how some of the situations can be addressed by refining the implementation. We extend the technique to perform Markov Chains speculatively, expanding the range of algorithms that maybe be accelerated by speculative execution to those with non-uniform move processing times. By simulating program runs we can predict the theoretical reduction in runtime that may be achieved by this technique. We compare how efficiently different architectures perform in using this method, and present experiments that demonstrate a runtime reduction of up to 35-42% where using conventional speculative moves would result in execution as slow, if not slower, than sequential processing.

关键词： Runtime Availability Computer architecture Computer simulation Monte Carlo methods Biological system modeling Computational modeling Bayesian methods Application software Computational biology

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A distributed and Energy Efficient Algorithm for Data Collection in Sensor Networks

A Distributed and Energy Efficient Algorithm for Data Collec...

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International Conference on parallel processing Workshops (ICPPW)

作者： Sarah Sharafkandi David H. C. Du Alireza Razavi Department of Computer Science and Engineering University of Minnesota Twin city MN USA

In wireless sensor networks, collection of raw sensor data at a base station provides the flexibility to perform offline detailed analysis on the data which may not be possible with innetwork data aggregation. However, lossless data collection consumes considerable amount of energy for communication while sensors usually have limited energy. In this paper, we propose a distributed and Energy efficient algorithm for Collection of Raw data in sensor networks called DECOR. DECOR exploits spatial correlation to reduce the communication energy in sensor networks with highly correlated data. In our approach, at each neighborhood, one sensor shares its raw data as a reference with the rest of sensors without any suppression or compression. Other sensors use this reference data to compress their observations by representing them in the forms of mutual differences. In a highly correlated network, transmission of reference data consumes significantly more energy than transmission of compressed data. Thus, we first attempt to minimize the number of reference transmissions. Then, we try to minimize the size of mutual differences. We derive analytical lower bounds for both these phases and based on our theoretical results, we propose a two-step distributed data collection algorithm which reduces the communication energy significantly compared to existing methods. In addition, we modify our algorithm for lossy communication channels and we evaluate its performance through simulation.

关键词： Base stations distributed databases image color analysis Correlation Approximation methods Bridges Propagation losses

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Message Driven Programming with S-Net: Methodology and Performance

Message Driven Programming with S-Net: Methodology and Perfo...

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International Conference on parallel processing Workshops (ICPPW)

作者： Frank Penczek Stephan Herhut Sven-Bodo Scholz Alex Shafarenko JungSook Yang Chun-Yi Chen Nader Bagherzadeh Clemens Grelck University of Herfordshire UK University of California Irvine USA University of Amsterdam Netherlands

Development and implementation of the coordination language S-NET has been reported previously. In this paper we apply the S-NET design methodology to a computer graphics problem. We demonstrate (i) how a complete separation of concerns can be achieved between algorithm engineering and concurrency engineering and (ii) that the S-NET implementation is quite capable of achieving performance that matches what can be achieved using low-level tools such as MPI. We find this remarkable as under S-NET communication, concurrency and synchronization are completely separated from algorithmic code. We argue that our approach delivers a flexible component technology which liberates application developers from the logistics of task and data management while at the same time making it unnecessary for a distributed computing professional to acquire detailed knowledge of the application area.

关键词： Corporate acquisitions Pixel Ray tracing Concurrent computing Rendering (computer graphics) Streaming media image color analysis

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parallel and distributed graph cuts by dual decomposition

Parallel and distributed graph cuts by dual decomposition

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Conference on Computer Vision and Pattern Recognition (CVPR)

作者： Petter Strandmark Fredrik Kahl Centre for Mathematical Sciences Lund University Sweden

Graph cuts methods are at the core of many state-of-the-art algorithms in computer vision due to their efficiency in computing globally optimal solutions. In this paper, we solve the maximum flow/minimum cut problem in parallel by splitting the graph into multiple parts and hence, further increase the computational efficacy of graph cuts. Optimality of the solution is guaranteed by dual decomposition, or more specifically, the solutions to the subproblems are constrained to be equal on the overlap with dual variables. We demonstrate that our approach both allows (i) faster processing on multi-core computers and (ii) the capability to handle larger problems by splitting the graph across multiple computers on a distributed network. Even though our approach does not give a theoretical guarantee of speedup, an extensive empirical evaluation on several applications with many different data sets consistently shows good performance. An open source implementation of the dual decomposition method is also made publicly available.

关键词： Computer vision distributed computing Concurrent computing Computer networks Computer aided manufacturing Application software Computational efficiency Tree graphs Grid computing

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Using the GPU and Multi-core CPU to Generate a 3D Oviduct through Feature Extraction from Histology Slides

Using the GPU and Multi-core CPU to Generate a 3D Oviduct th...

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International Workshop on High Performance Computational Systems Biology, HIBI

作者： Mark Burkitt Dawn Walker Daniela M. Romano Alireza Fazeli Department of Computer Science University of Sheffield Sheffield UK Academic Unit of Reproductive and Developmental Medicine University of Sheffield Sheffield UK

Extracting information about the structure of biological tissue from static image data is a complex task which requires a series of computationally intensive operations. Here we present how the power of multi-core CPUs and massively parallel GPUs have been utilised to extract information about the shape, size and path followed by the mammalian oviduct, called the fallopian tube in humans, from histology images, to create a realistic 3D virtual organ for use in predictive computational models. Histology images from a mouse oviduct were processed, using a combination of GPU and multi-core CPU techniques, to identify the individual cross-sections and determine the 3D path that the tube follows through the tissue. This information was then related back to the histology images, linking the 2D cross-sections with their corresponding 3D position along the oviduct. Measurements were then taken from the images and used to computationally generate a series of linear 2D spline cross-sections for the length of the oviduct, which were bound to the 3D path of the tube using a novel particle system based technique that provides smooth resolution of self intersections and crossovers from adjacent sections. This results in a unique 3D model of the oviduct, which is based on measurements of histology slides and therefore grounded in reality. The GPU is used for the processor intensive operations of image processing and particle physics based simulations, significantly reducing the time required to generate a complete model. A set of models created using this technique is being used to investigate the influence that the 3D structure of the oviductal environment has on sperm transport and navigation.

关键词： Three dimensional displays Electron tubes Graphics processing unit Pixel Solid modeling Computational modeling Biological system modeling

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Low cost VLSI discrete wavelet transform and FIR filters architectures for very high-speed signal and image processing

Low cost VLSI discrete wavelet transform and FIR filters arc...

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IEEE International Conference on Cybernetic Intelligent Systems, CIS

作者： Mountassar Maamoun Rafik Bradai Abdelhamid Meraghni Rachid Beguenane Department of Electronics University of Blida Burgas Algeria LSIC Laboratory Ecole Normale Supérieure Kouba Algiers Algeria Department of Electrical and Computer Engineering Royal Military College of Canada Kingston Canada

This paper presents new VLSI architectures for finite impulse response (FIR) filters and discrete wavelet transform, intended for very high-speed signal and image processing. The proposed architectures, based on combining pipeline and parallel arithmetic methods, provide a new and very fast convolution approach with a reduced critical path. The key to this is a clever use of D-latches and multipliers which are efficiently distributed. Furthermore, an advanced discrete wavelet transform (DWT) approach, with an area-efficient architecture, is designed to produce one output in every clock cycle. As a result, a very high-speed is attained. The proposed structure can increase the work frequency (85%) at a low cost of additional hardware elements (55%). The systems are verified, using JPEG2000 coefficients filters, on Xilinx Field Programmable Gate Array (FPGA) devices.

关键词： Finite impulse response filter Computer architecture Adders Discrete wavelet transforms Low pass filters Convolution

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3D Wave field phase retrieval from multi-plane observations

3D Wave field phase retrieval from multi-plane observations

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3DTV Conference

作者： Artem Migukin Vladimir Katkovnik Jaakko Astola Department of Signal Processing Tampere University of Technology Tampere Finland

We reconstruct a spatially distributed three-dimensional (3D) wave field from a number of intensity observations, obtained in different sensor planes, parallel to the object plane. The proposed algorithm can be treated as a multiple plane iterative Gerchberg-Saxton algorithm [1]. It is obtained from the best linear estimate of the complex-valued object distribution derived for the complex-valued observations. This estimator is modified for the intensity measurements in the sensor planes. The algorithm is studied by numerical experiments performed for amplitude and phase object distributions. It is shown that the proposed method allows reconstructing the whole 3D wave fields for different setup parameters. This technique can be applied for 3D imaging. The comparison versus the successive iterative method [2] shows an accuracy advantage of the proposed algorithm provided that the type of modulation in the object plane is known.

关键词： Signal processing algorithms image reconstruction Iterative algorithms Phase measurement Optical imaging Optical interferometry Iterative methods Holography Reconstruction algorithms Optical scattering

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Pipelining parallel image compositing and delivery for efficient remote visualization

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JOURNAL OF parallel AND distributed COMPUTING 2009年第3期69卷 230-238页

作者： Wu, Qishi Gao, Jinzhu Chen, Zizhong Zhu, Mengxia Univ Memphis Dept Comp Sci Memphis TN 38152 USA Univ Pacific Dept Comp Sci Stockton CA 95211 USA Colorado Sch Mines Dept Math & Comp Sci Golden CO 80401 USA So Illinois Univ Dept Comp Sci Carbondale IL 62901 USA

Scientific datasets of large volumes generated by next-generation computational sciences need to be transferred and processed for remote visualization and distributed collaboration among a geographically dispersed team of scientists. parallel visualization using high-performance computing facilities is a typical approach to processing such increasingly large datasets. We propose an optimized image compositing scheme with linear pipeline and adaptive transport to support efficient image delivery to a remote client. The proposed scheme arranges an arbitrary number of parallel processors within a cluster in a linear order and divides the image into a carefully selected number of segments, which flow through the linear incluster pipeline and wide-area networks to the remote client consecutively. We analytically determine the segment size that minimizes the final image display time and derive the conditions where the proposed image compositing and delivery scheme outperforms the traditional schemes including the binary swap algorithm. In order to match the transport throughput for image delivery over wide-area networks to the pipelining rate for image compositing within the cluster, we design a class of transport protocols using stochastic approximation methods that are able to stabilize the data flow at a target rate. The experimental results from remote visualization of large-scale scientific datasets justify the correctness of our theoretical analysis and illustrate the superior performances of the proposed method. (C) 2008 Elsevier Inc. All rights reserved.

关键词： image compositing Pipelining Transport control Remote visualization parallel and distributed systems

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Encoding multiple words simultaneously in reading is implausible

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TRENDS IN COGNITIVE SCIENCES 2009年第3期13卷 115-119页

作者： Reichle, Erik D. Liversedge, Simon P. Pollatsek, Alexander Rayner, Keith Univ Pittsburgh Pittsburgh PA 15260 USA Univ Southampton Southampton SO17 1BJ Hants England Univ Massachusetts Amherst MA 01003 USA Univ Calif San Diego La Jolla CA 92093 USA

Several prominent models of reading posit that attention is distributed to support the parallel lexical processing of multiple words. We contend that the auxiliary assumptions underlying this attention-gradient hypothesis are not well founded. Here, we address three specific issues related to the ongoing debate about attention allocation during reading: (i) why the attention-gradient hypothesis is widely endorsed, (ii) why processing several words in parallel in reading is implausible and (iii) why attention must be allocated to only one word at a time. Full consideration of these arguments supports the hypothesis that attention is allocated serially during reading.

关键词： ATTENTION WORD processing ENCODING READING SIMULATION methods & models COGNITIVE science

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