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IEEE Annual Joint Conference: INFOCOM, IEEE computer and Communications Societies

作者： P. Warkhede S. Suri G. Varghese Cisco Systems. Computer Science Computer Science and Engineering UC San Diego CA USA Computer Science University of California Santa Barbara CA USA Cisco Systems. Computer Science Computer Science and Engineering UC San Diego CA

ISBN: (纸本)0780370163

Routers can use packet classification to support advanced functions. Routers with packet classification capability can forward packets based on multiple header fields, such as source address, protocol type, or application port numbers. The destination-based forwarding can be thought of as one-dimensional packet classification. While several efficient solutions are known for the one-dimensional IP lookup problem, the multi-dimensional packet classification has proved to be far more difficult. While an O(log w) time scheme is known for the IP lookup, Srinivisan et al. (1999) show a lower bound of /spl Omega/(/spl omega//sup k-1/) for k-dimensional filter lookup, where /spl omega/ is the number of bits in a header field. In particular, this lower bound precludes the possibility of a binary search like scheme even for 2-dimensional filters. In this paper, we examine this lower bound more closely, and discover that the lower bound depends crucially on conflicts in the filter database. We then show that for two-dimensional conflict-free filters, a binary search scheme does work! Our lookup scheme requires O(log/sup 2/ /spl omega/) hashes in the worst-case, and uses O(n log/sup 2/ /spl omega/) memory. Alternatively, our algorithm can be viewed as making O (log /spl omega/) calls to a prefix lookup scheme. It has been observed in practice that filter databases have very few conflicts, and these conflicts can be removed by adding additional filters (one per conflict). Thus, our scheme may also be quite practical. Our simulation and experimental results show that the proposed scheme also performs as good as or better than existing schemes.

关键词： Filters Virtual private networks Filtering Routing Bandwidth Databases Packet switching computer science Access control Access protocols

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Trace-driven system-level power evaluation of system-on-a-chip peripheral cores 01

Trace-driven system-level power evaluation of system-on-a-ch...

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Proceedings of the 2001 Asia and South Pacific Design Automation Conference

作者： Tony D. Givargis Frank Vahid Jörg Henkel Department of Computer Science and Engineering University of California Riverside CA Department of Computer Science and Engineering University of California Riverside CA and Center for Embedded Computer System at UC Irvine C&C Research Laboratories NEC 4 Independence Way Princeton NJ

ISBN: (纸本)9780780366343

Our earlier work for fast evaluation of power consumption of general cores in a system-on-a-chip described techniques that involved isolating high-level instructions of a core, measuring gate-level power consumption per instruction, and then annotating a system-level simulation model with the obtained data. In this work, we describe a method for speeding up the evaluation further, through the use of instruction traces and trace simulators for every core, not just microprocessor cores. Our method shows noticeable speedups at an acceptable loss of accuracy. We show that reducing trace sizes can speed up the method even further. The speedups allow for more extensive system-level power exploration and hence better optimization.

关键词： cores

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Novel all-optical 10 Gbp/s RZ-to-NRZ conversion using SOA-loop-mirror

Novel all-optical 10 Gbp/s RZ-to-NRZ conversion using SOA-lo...

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Optical Fiber Communication (OFC) Conference

作者： Hyuek Jae Lee S.J.B. Yoo Chang Soo Park Optical Switching and Communications Systems Laboratory Department of Electrical and Computer Engineering UC Davis Engineering II Davis CA USA Gwangju Institute of Science and Technology Gwangju South Korea

ISBN: (纸本)1557526559

The authors propose and demonstrate a novel all-optical return-to-zero (RZ) to non-return-to-zero (NRZ) data format conversion using a semiconductor optical amplifier (SOA) loop mirror. Error free transmission up to 78 km for the NRZ format converted data at 10 Gb/s is achieved. Also, the proposed method shows better transmission performance than the conventional Mach-Zehnder modulation method.

关键词： Optical signal processing Semiconductor optical amplifiers Optical filters Mirrors Wavelength division multiplexing Fiber nonlinear optics Optical modulation Optical fibers Optical interferometry Optical pulse generation

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Rao-blackwellised particle filtering via data augmentation 01

Rao-blackwellised particle filtering via data augmentation

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Proceedings of the 14th International Conference on Neural Information Processing Systems: Natural and Synthetic

作者： Christophe Andrieu Nando de Freitas Arnaud Doucet Statistics Group University of Bristol University Walk Bristol UK Computer Science UC Berkeley Berkeley CA EE Engineering University of Melbourne Parkville Victoria Australia

In this paper, we extend the Rao-Blackwellised particle filtering method to more complex hybrid models consisting of Gaussian latent variables and discrete observations. This is accomplished by augmenting the models with artificial variables that enable us to apply Rao-Blackwellisation. Other improvements include the design of an optimal importance proposal distribution and being able to swap the sampling an selection steps to handle outliers. We focus on sequential binary classifiers that consist of linear combinations of basis functions, whose coefficients evolve according to a Gaussian smoothness prior. Our results show significant improvements.

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Demonstration of a hybrid collisional soft-x-ray laser

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Physical Review A 2001年第3期63卷 033803-033803页

作者： K. A. Janulewicz J. J. Rocca F. Bortolotto M. P. Kalachnikov V. N. Shlyaptsev W. Sandner P. V. Nickles Max Born Institute Max-Born-Strasse 2A D-12489 Berlin Germany Department of Electrical and Computer Engineering Colorado State University Fort Collins Colorado 80523 Department of Applied Science UC Davis-Livermore California 94550

We report on a demonstration of x-ray-ultraviolet amplification following collisional excitation in a discharge-created plasma waveguide irradiated by a picosecond optical laser pulse. A capillary discharge was used to generate a sulfur plasma column with a large concentration of Ne-like ions and a radially concave electron density profile. The intense short laser pulse rapidly heated the electrons, producing amplification in the 3p1S0–3s1P1 transition of Ne-like S at 60.8 nm. The integrated gain-length product obtained exciting a 3-cm-long capillary with a 0.46-J short laser pulse is 6.8. The beam divergence was observed to decrease as a function of plasma column length, reaching 2.5 mrad for 30-mm-long capillaries. This hybrid laser pumping scheme could lead to a new generation of efficient tabletop soft-x-ray lasers.

关键词： .divergence capillary rapidly picosecond generate laser pulse irradiated heated Ne-like short laser gain-length cm-long plasma column length soft ray lasers

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A Constrained Multiple Raw Materials Manufacturing Batch Sizing Problem

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International Transactions in Operational Research 2001年第2期8卷 121-138页

作者： Sarker, Ruhul Runarsson, Thomas P. Newton, Charles School of Computer Science UC University of New South Wales Canberra ACT 2600 Australia Department of Mechanical Engineering University of Iceland Reykjavik IS-107 Iceland

The purpose of this research is to determine an optimal batch size for a product, and the purchasing policy of associated raw materials, for a manufacturing firm. Like any other practical situation, this manufacturing firm has a limited storage space, and transportation fleet of known capacity. The mathematical formulation of the problem indicates that the model is a constrained nonlinear integer program. Considering the complexity of solving such a model, we investigate the use of genetic algorithms (GAs) for solving this model. We develop both binary and real coded genetic algorithms with six different penalty functions. In addition, we develop a new procedure to solve constrained optimization models using penalty function based GAs. The real coded genetic algorithms work well for the batch sizing problems. The detailed computational experiences are presented. International Federation of Operational Research Societies 2001.

关键词： Batch sizing problem Genetic algorithm Nonlinear integer program Penalty method

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Extractors and pseudo-random generators with optimal seed length 00

Extractors and pseudo-random generators with optimal seed le...

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32nd Annual ACM Symposium on Theory of Computing

作者： Impagliazzo, Russell Shaltiel, Ronen Wigderson, Avi Computer Science and Engineering UC San Diego 9500 Gilman Drive San Diego CA United States Department of Computer Science Hebrew University Jerusalem Israel Institute for Advanced Study Princeton United States

ISBN: (纸本)9781581131840

We give the first construction of a pseudo-random generator with optimal seed length that uses (essentially) arbitrary hardness. It builds on the novel recursive use of the NW-generator in [8], which produced many optimal generators one of which was pseudo-random. This is achieved in two stages - first significantly reducing the number of candidate generators, and then efficiently combining them into one. We also give the first construction of an extractor with optimal seed length, that can handle sub-polynomial entropy levels. It builds on the fundamental connection between extractors and pseudo-random generators discovered by Trevisan, combined with construction above. Moreover, using Kolmogorov Complexity rather than circuit size in the analysis gives super-polynomial savings for our construction, and renders our extractors better than known for all entropy levels.

关键词： Random number generation

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Robust full bayesian methods for neural networks

Robust full bayesian methods for neural networks

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13th Annual Neural Information Processing Systems Conference, NIPS 1999

作者： Andrieu, Christophe De Freitas, João F.G. Doucet, Arnaud Cambridge University Engineering Department Cambridge CB2 1PZ United Kingdom UC Berkeley Computer Science 387 Soda Hall Berkeley CA 94720-1776 United States

ISBN: (纸本)0262194503

In this paper, we propose a full Bayesian model for neural networks. This model treats the model dimension (number of neurons), model parameters, regularisation parameters and noise parameters as random variables that need to be estimated. We then propose a reversible jump Markov chain Monte Carlo (MCMC) method to perform the necessary computations. We find that the results are not only better than the previously reported ones, but also appear to be robust with respect to the prior specification. Moreover, we present a geometric convergence theorem for the algorithm.

关键词： Bayesian networks

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Speech modelling using subspace and EM techniques

Speech modelling using subspace and EM techniques

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13th Annual Neural Information Processing Systems Conference, NIPS 1999

作者： Smith, Gavin De Freitas, João F.G. Robinson, Tony Niranjan, Mahesan Cambridge University Engineering Department Cambridge CB2 1PZ United Kingdom Computer Science Division 487 Soda Hall UC Berkeley CA 94720-1776 United States Computer Science Sheffield University Sheffield S1 4DP United Kingdom

ISBN: (纸本)0262194503

The speech waveform can be modelled as a piecewise-stationary linear stochastic state space system, and its parameters can be estimated using an expectation-maximisation (EM) algorithm. One problem is the initialisation of the EM algorithm. Standard initialisation schemes can lead to poor formant trajectories. But these trajectories however are important for vowel intelligibility. The aim of this paper is to investigate the suitability of subspace identification methods to initialise EM. The paper compares the subspace state space system identification (4SID) method with the EM algorithm. The 4SID and EM methods are similar in that they both estimate a state sequence (but using Kalman filters and Kalman smoothers respectively), and then estimate parameters (but using least-squares and maximum likelihood respectively). The similarity of 4SID and EM motivates the use of 4SID to initialise EM. Also, 4SID is non-iterative and requires no initialisation, whereas EM is iterative and requires initialisation. However 4SID is sub-optimal compared to EM in a probabilistic sense. During experiments on real speech, 4SID methods compare favourably with conventional initialisation techniques. They produce smoother formant trajectories, have greater frequency resolution, and produce higher likelihoods.

关键词： Maximum likelihood

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Fail-aware datagram service

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IEE Proceedings: Software 1999年第2期146卷 58-74页

作者： Fetzer, C. Cristian, F. Department of Computer Science and Engineering UC San Diego San Diego CA 92093-0114 United States

In distributed real-time systems it is often useful for a process p to know that another process q will not use a certain piece of information that p has sent to q beyond a certain deadline. If p can learn about the occurrence of the deadline by simply measuring the passage of time on its own local clock, we call this kind of information exchange `communication by time'. It is shown that communication by time is possible in systems where there exists no a priori known upper bound on the transmission delay of messages and where clocks are not synchronized. It is sufficient if one can compute an a posteriori upper bound on the transmission delay of a message m, i.e. at the time when m is delivered. The authors show how one can compute an a posteriori upper bound on the one-way message transmission delay of a message even if the clocks of the sender and receiver process are not synchronized. The method is used to design a fail-aware datagram service. This service supports communication by time by delivering all messages whose computed one-way transmission delays are smaller than a given bound as `fast' and all other messages as `slow'. The properties of this service are specified and an efficient implementation is provided for it. To illustrate how this service supports communication by time, a leader election protocol that guarantees the existence of at most one leader at any real time is sketched and it is shown how this allows the detection of out-of-date sensor information in process control applications.

关键词： Real time systems

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