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Data Compression Conference (DCC)

作者： Vijay Chellappa P.C. Cosman G.M. Voelker Department of Electrical and Computer Engineering Department of Computer Science and Engineering University of California San Diego La Jolla CA USA

Video codecs that use motion compensation have shown PSNR gains from the use of multiple frame prediction, in which more than one past reference frame is available for motion estimation. In dual frame motion compensation, one short-term reference frame and one long-term reference frame are available for prediction. In this paper, we propose a dual frame motion compensation technique that allocates bits unevenly among frames to periodically create a high-quality frame that serves as the long-term reference frame for some time. By modifying an MPEG-4 encoder to use this technique on a set of video sequences, we show that it outperforms a normal dual frame motion compensation scheme in which the long-term reference frames are regular frames that are not allocated any extra rate.

关键词： Motion compensation Video codecs Motion estimation MPEG 4 Standard Video sequences Transform coding Bit rate Delay effects computer science PSNR

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Performance analysis of GYRO: a tool evaluation

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Journal of Physics: Conference Series 2005年第1期16卷

作者： P Worley J Candy L Carrington K Huck T Kaiser G Mahinthakumar A Malony S Moore D Reed P Roth H Shan S Shende A Snavely S Sreepathi F Wolf Y Zhang Oak Ridge National Laboratory PO Box 2008 Oak Ridge TN 37831-6016 USA General Atomics PO Box 85608 San Diego CA 92186-5608 USA San Diego Supercomputer Center University of California San Diego 9500 Gilman Drive La Jolla California 92093-0505 USA Computer and Information Science Department 1202 University of Oregon Eugene OR 97403-1202 USA Department of Civil Engineering North Carolina State University Raleigh NC 27695-7908 USA Innovative Computing Laboratory University of Tennessee 1122 Volunteer Blvd. Suite 413 Knoxville TN 37996-3450 USA Renaissance Computing Institute University of North Carolina at Chapel Hill CB 7583 Carr Building Chapel Hill NC 27599-7583 USA Lawrence Berkeley National Laboratory Berkeley CA 94720 USA Department of Computer Science North Carolina State University Raleigh NC 27695-7908 USA

The performance of the Eulerian gyrokinetic-Maxwell solver code GYRO is analyzed on five high performance computing systems. First, a manual approach is taken, using custom scripts to analyze the output of embedded wallclock timers, floating point operation counts collected using hardware performance counters, and traces of user and communication events collected using the profiling interface to Message Passing Interface (MPI) libraries. Parts of the analysis are then repeated or extended using a number of sophisticated performance analysis tools: IPM, KOJAK, SvPablo, TAU, and the PMaC modeling tool suite. The paper briefly discusses what has been discovered via this manual analysis process, what performance analyses are inconvenient or infeasible to attempt manually, and to what extent the tools show promise in accelerating or significantly extending the manual performance analyses.

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Pipelined test of SOC cores through test data transformations

Pipelined test of SOC cores through test data transformation...

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IEEE European Test Symposium (ETS)

作者： O. Sinanoglu A. Orailoglu Computer Science and Engineering Department University of California La Jolla CA USA

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NEC: Node energy based clustering protocol for wireless sensor networks with guaranteed connectivity

Lecture Notes in Computer Science (including subseries Lectu...

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Lecture Notes in computer science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 2004年 3347卷 75-84页

作者： Dhar, Shilpa Roy, Krishnendu Kannan, Rajgopal Department of Computer Science Louisiana State University Baton Rouge LA 70803 United States Department of Electrical and Computer Engineering Louisiana State University Baton Rouge LA 70803 United States

Wireless sensor networks are continually being deployed in various application areas which are posing various new challenges. Yet, one problem that still remains central to the operability and applicability of sensor networks is the limited energy of the sensor nodes which directly limits the network lifetime. Various schemes have been proposed to optimize the energy conservation, some of which use network-redundancy to switch off the radios of some nodes. Ensuring minimum connectivity in such a case is the main objective, which the existing papers address inadequately. We propose a scheme of topology control based on the concept of strong and weak nodes. In our protocol clustering is done keeping in mind the lifetime of all the nodes that are awake and not just the lifetime of the cluster-head hence ensuring that minimum connectivity is always guaranteed. © Springer-Verlag 2004.

关键词： Energy conservation

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Reciprocal Space Mapping of MBE-Grown HgCdTe Heterostructures

Reciprocal Space Mapping of MBE-Grown HgCdTe Heterostructure...

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Conference on Optoelectronic and Microelectronic Materials and Devices

作者： R.H. Sewell C.A. Musca J.M. Dell L. Faraone T. Dieing B. Usher School of Electrical Electronic and Computer Engineering University of Western Australia Perth Australia Department of Electronic Engineering La Trobe University Bundoora Australia

lattice mismatch between substrates and epitaxial layers of different mole-fractions can create a variety of distortions and defects in HgCdTe epilayers, thus degrading the performance of infrared detectors fabricated from this material. X-ray diffractometry is a sensitive non-destructive technique, which allows in-depth characterisation of the crystal lattice prior to detector fabrication. We present results of triple-axis diffractometry (TAD) performed on single and double layer HgCdTe films grown on (211)B CdZnTe substrates by molecular beam epitaxy (MBE). The positions of both surface-symmetric and asymmetric diffraction peaks have been used to extract lattice spacings parallel and perpendicular to the (211) growth direction. The unstrained lattice parameter of each epilayer has been calculated assuming that the layers are elastically strained. The low-symmetry of the (211) plane, coupled with the anisotropic elasticity of zinc-blende semiconductors, results in monoclinic distortion of the lattice, as observed in these samples. In double layer samples, the mosaicity of both layers is greater than that observed in single epilayers. Annealed samples show greater lattice distortion than as-grown samples

关键词： lattices Molecular beam epitaxial growth Substrates X-ray diffraction Epitaxial layers Degradation Infrared detectors Crystalline materials X-ray detection X-ray detectors

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Scalability in adaptive multi-metric overlays

Scalability in adaptive multi-metric overlays

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International Conference on Distributed Computing Systems

作者： A. Rodriguez D. Kostic A. Vahdat Department of Computer Science Duke University Durham NC USA Department of Computer Science and Engineering University of California San Diego La Jolla CA USA

Increasing application requirements have placed heavy emphasis on building overlay networks to efficiently deliver data to multiple receivers. A key performance challenge is simultaneously achieving adaptivity to changing network conditions and scalability to large numbers of users. In addition, most current algorithms focus on a single performance metric, such as delay or bandwidth, particular to individual application requirements. We introduce a two-fold approach for creating robust, high-performance overlays called adaptive multimetric overlays (AMMO). First, AMMO uses an adaptive, highly-parallel, and metric-independent protocol, TreeMaint, to build and maintain overlay trees. Second, AMMO provides a mechanism for comparing overlay edges along specified application performance goals to guide TreeMaint transformations. We have used AMMO to implement and evaluate a single-metric (bandwidth-optimized) tree similar to Overcast and a two-metric (delay-constrained, cost-optimized) overlay.

关键词： Scalability Peer to peer computing Probes Delay Bandwidth Protocols computer science Measurement Data engineering Drives

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Memory-constrained data locality optimization for tensor contractions

Memory-constrained data locality optimization for tensor con...

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16th International Workshop on languages and Compilers for Parallel Computing, LCPC 2003

作者： Bibireata, Alina Krishnan, Sandhya Baumgartner, Gerald Cociorva, Daniel lam, Chi-Chung Sadayappan, P. Ramanujam, J. Bernholdt, David E. Choppella, Venkatesh Department of Computer and Information Science The Ohio State University ColumbusOH43210 United States Department of Electrical and Computer Engineering Louisiana State University Baton RougeLA70803 United States Oak Ridge National Laboratory Oak RidgeTN37831 United States

ISBN: (纸本)9783540246442

The accurate modeling of the electronic structure of atoms and molecules involves computationally intensive tensor contractions over large multi-dimensional arrays. Efficient computation of these contractions usually requires the generation of temporary intermediate arrays. These intermediates could be extremely large, requiring their storage on disk. However, the intermediates can often be generated and used in batches through appropriate loop fusion transformations. To optimize the performance of such computations a combination of loop fusion and loop tiling is required, so that the cost of disk I/O is minimized. In this paper, we address the memory-constrained data-locality optimization problem in the context of this class of computations. We develop an optimization framework to search among a space of fusion and tiling choices to minimize the data movement overhead. The effectiveness of the developed optimization approach is demonstrated on a computation representative of a component used in quantum chemistry suites. © Springer-Verlag Berlin Heidelberg 2004.

关键词： Quantum chemistry

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Binary image transformation using two-dimensional chaotic maps

Binary image transformation using two-dimensional chaotic ma...

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International Conference on Pattern Recognition

作者： F. Belkhouche U. Qidwai I. Gokcen D. Joachim Department of Electrical Engineering & Computer Science Tulane University New Orleans LA USA

We present an algorithm for binary image transformation using chaotic maps. Because of its random-like behavior, chaos is a good candidate for encryption. We show that a two-dimensional discrete time dynamical system with one positive Lyapunov exponent allows the transformation of the image in an unpredictable manner. The suggested algorithm acts on the pixel position, where the diffusion property resulting from the sensitivity to the initial states is used to accomplish the transformation in a random-like way. The suggested algorithm uses three types of keys: initial state, external parameters and the number of iterations. Using the so-called Henon map as an example, we show that the algorithm produces almost uncorrelated images even when the keys are slightly changed, making it an attractive and fast method for image encryption.

关键词： Chaos Chaotic communication Cryptography Pixel Image coding Image processing computer science Information security Banking Broadcasting

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SVM vs regularized least squares classification

SVM vs regularized least squares classification

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International Conference on Pattern Recognition

作者： P. Zhang J. Peng Electrical Engineering and Computer Science Department Tulane University New Orleans LA USA

Support vector machines (SVMs) and regularized least squares (RLS) are two recent promising techniques for classification. SVMs implement the structure risk minimization principle and use the kernel trick to extend it to the nonlinear case. On the one hand, RLS minimizes a regularized functional directly in a reproducing kernel Hilbert space defined by a kernel. While both have a sound mathematical foundation, RLS is strikingly simple. On the other hand, SVMs in general have a sparse representation of solutions. In addition, the performance of SVMs has been well documented but little can be said of RLS. This paper applies these two techniques to a collection of data sets and presents results demonstrating virtual identical performance by the two methods.

关键词： Support vector machines Support vector machine classification Least squares methods Resonance light scattering Kernel Risk management Training data Hilbert space Object recognition Cancer

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Equivalent circuit of an aperture-coupled lossy cavity

Equivalent circuit of an aperture-coupled lossy cavity

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Antennas and Propagation Society International Symposium

作者： Yeqin Huang Department of Electrical Engineering and Computer Science Tulane University New Orleans LA USA

ISBN: (纸本)0780383028

The equivalent circuit of an aperture-coupled cavity is derived via field analysis. To determine the input impedance of a cavity resonator coupled with a waveguide, the equivalent circuit is derived by making use of integral equations and the eigenfunction expansion of dyadic Green's functions. It is shown that the input impedance of the aperture-coupled cavity is the sum of a capacitive reactance and a load impedance resulting from an infinite number of inductively coupled parallel RLC meshes connected in series.

关键词： Equivalent circuits Integral equations Impedance Green's function methods Coupling circuits Eigenvalues and eigenfunctions Capacitors Maxwell equations Magnetic fields Cavity resonators

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