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International Conference on Dependable Systems and Networks (DSN)

作者： Jong Kim K.G. Shin High Performance Computer Laboratory Department of CSE Pohang University of Science and Technology Pohang South Korea Real-Time Computer Laboratory Department of EECS University of Michigan Ann Arbor MI USA

When a client requests a real-time connection that requires an excessive amount of resources and/or a very high level of QoS, the network service provider may have to reject the request, and only a small number of connections could be accepted. On the other hand, if the client requests only the minimum level of QoS, he may receive only a bare-bones service even when there are plenty of resources available. One way of utilizing resources efficiently is to specify flexible (elastic) QoS requirements that can be adapted to the availability of network resources. S.J. Han et al. (1997) proposed to allocate one primary channel and one or more backup channels to each dependable real-time (DR) connection. One drawback of this scheme is the severe reduction in number of DR connections that can be accommodated, due mainly to the need for reserving resources for backups. This is equivalent to wasting precious resources in the absence of faults as far as the system's ability of accepting DR connections is concerned. By using elastic QoS for this DR communication service, one can accept substantially more DR connections and improve the utilization of resources efficiently and significantly. We analyze the DR communication service with elastic QoS. Fault tolerance is achieved by allocating one backup channel to each DR connection. A Markov model is developed and used to analyze the average QoS level allotted to the primary channel of each DR connection. Our evaluation results show that the proposed Markov model accurately represents the behavior of DR connections with elastic QoS.

关键词： Application software Quality of service Fault tolerance Web and internet services Time factors Delay Contracts Availability Bandwidth IP networks

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Informing algorithms for efficient scheduling of synchronizing threads on multiprogrammed SMPs

Informing algorithms for efficient scheduling of synchronizi...

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International Conference on Parallel Processing (ICPP)

作者： C.D. Antonopoulos D.S. Nikolopoulos T.S. Papatheodorou High Performance Information Systems Laboratory Computer Engineering and Informatics Department University of Patras Patras Greece Computers and Systems Research Lab Coordinated Science Laboratory University of Illinois Urbana-Champaign Urbana IL USA

We present novel algorithms for efficient scheduling of synchronizing threads on multiprogrammed SMPs. The algorithms are based on intra-application priority control of synchronizing threads. We refer to such algorithms with the term "informing algorithms". Prerequisite for informing algorithms is the use of an efficient communication medium between the user- and kernel-level and the existence of in-kernel mechanisms that allow the applications to cooperate with the OS scheduler. The applications are given the opportunity to influence, in a non-intrusive manner, the scheduling decisions concerning their threads. We compare the performance of our informing algorithms with the performance of corresponding scheduler-oblivious algorithms under multiprogramming. We experimented on a small-scale, Intel x86-based SMP, running Linux, using both microbenchmarks and applications from the Splash-2 benchmark suite. The results substantiate the superiority of our approach and indicate that the philosophy of informing algorithms may be applicable in a wide range of algorithms and architectures.

关键词： Scheduling algorithm Yarn Switched-mode power supply Processor scheduling Information systems Degradation Laboratories Systems engineering and theory Informatics Communication system control

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Nonlinear Optics with Phase-Controlled Pulses in the Sub-Two-Cycle Regime

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Physical Review Letters 2001年第24期86卷 5462-5462页

作者： U. Morgner R. Ell G. Metzler T. R. Schibli F. X. Kärtner J. G. Fujimoto H. A. Haus E. P. Ippen High Frequency and Quantum Electronics Laboratory University of Karlsruhe Engesserstrasse 5 D-76128 Karlsruhe Germany Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge Massachusetts 02139

Nonlinear optical effects due to the phase between carrier and envelope are observed with 5 fs pulses from a Kerr-lens mode-locked Ti:sapphire laser. These sub-two-cycle pulses with octave spanning spectra are the shortest pulses ever generated directly from a laser oscillator. Detection of the carrier-envelope phase slip is made possible by simply focusing the short pulses directly from the oscillator into a BBO crystal. As a further example of nonlinear optics with such short pulses, the interference between second- and third-harmonic components is also demonstrated.

关键词： Nonlinear optics

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New algorithms for computing directional discrete Fourier transforms

New algorithms for computing directional discrete Fourier tr...

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IEEE International Conference on Image Processing

作者： M.S. Pattichis R. Zhou B. Raman Department of Electrical and Computer Engineering Image and Video Processing and Communications Laboratory USA Albuquerque High Performance Computing Center University of New Mexico Albuquerque NM USA

New algorithms for computing the discrete Fourier transform (DFT) spectra along different directions are derived and implemented. For computing the DFT spectrum along any given direction (containing N DFT frequencies), a new algorithm is presented that requires N(N-1) additions and a single 1-D FFT. As expected, for a single direction, the directional FFT algorithm is significantly faster than standard 2-D FFT algorithms that compute the entire spectrum (all results are compared against FFTW and FFTPACK). A scalable extension of the unidirectional algorithm for computing the entire DFT spectrum is also derived and implemented. The three most promising features of the new algorithm are that: (i) computation scales nearly linearly with the number of DFT frequencies computed, (ii) the algorithm uses a reduced number of multiplications (yet uses more additions), and (iii) it is more accurate.

关键词： Discrete Fourier transforms Flexible printed circuits high performance computing Frequency Laboratories Electronic mail Scientific computing Fast Fourier transforms Shape MPEG 4 Standard

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Nonlinear optics with phase-controlled pulses in the sub-two-cycle regime

Nonlinear optics with phase-controlled pulses in the sub-two...

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Quantum Electronics and Laser science Conference (QELS)

作者： U. Morgner R. Ell G. Metzler T.R. Schibli F.X. Kartner J.G. Fujimoto E.P. Ippen High-Frequency and Quantum Electronics Laboratory University of Karlsruhe Karlsruhe Germany Department of Electrical Engineering and Computer Science Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge USA

Summary form only given. Very recently, two groups have observed and stabilized the pulse-to-pulse carrier-envelope phase slip /spl Delta//spl phi/ by spectrally broadening femtosecond laser pulses in an external optical fiber. In this paper we report the determination and stabilization of /spl Delta//spl phi/ using pulses obtained directly from a mode-locked laser itself. We have done this both by monitoring the coherent interference of the fundamental pulse with its second harmonic and by observing a similar interference between the second and third harmonic.

关键词： Nonlinear optics Optical pulses Frequency Interference Optical interferometry Ultrafast optics Pulse measurements Ultrafast electronics Electrons Laboratories

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Few-cycle-pulse generation and its applications

Few-cycle-pulse generation and its applications

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Pacific Rim Conference on Lasers and Electro-Optics (CLEO/Pacific Rim)

作者： F.X. Kartner U. Morgner R. Ell E.P. Ippen J.G. Fujimoto V. Scheuer G. Angelow T. Tschudi Department of Electrical Engineering and Information Technology High-Frequency and Quantum Electronics Laboratory University of Karlsruhe Karlsruhe Germany Department of Electrical Engineering and Computer Science Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge MA USA Institute of Applied Physics Technical University of Darmstadt Darmstadt Germany

Sub-two-cycle optical pulses (5 fs) with spectra extending over more than one octave are generated directly from a Kerr-lens modelocked (KLM) Ti:sapphire laser. Applications of this broadband source in optical coheren... 详细信息

关键词： Mirrors Optical pulse generation Bandwidth Nonlinear optics Laser modes Optical resonators Pulse compression methods Space vector pulse width modulation Oscillators Laboratories

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Ultrahigh resolution, functional optical coherence tomography using state of the art femtosecond laser technology

Ultrahigh resolution, functional optical coherence tomograph...

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Pacific Rim Conference on Lasers and Electro-Optics (CLEO/Pacific Rim)

作者： W. Drexler U. Morgner F.X. Kartner R.K. Ghanta J.S. Schuman J.G. Fujimoto Institute of Medical Physics University of Technology Vienna Vienna Austria Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge MA USA Institute of Medical Physics University of Vienna Vienna Austria Institute for High-Frequency Technology Quantum Electronics University of Karlsruhe Karlsruhe Germany New England Eye Center Tufts University School of Medicine Boston MA USA New England Eye Center School of Medicine Boston MA USA

Using state of the art femtosecond laser technology, in vivo optical coherence tomography imaging with subcellular level resolution is achieved, enabling optical biopsy, the in situ visualization of biological tissue at the level of histopathology. Spectroscopic OCT allows the extraction of spatially resolved functional or biochemical properties.

关键词： Tomography Ultrafast optics Spatial resolution Biomedical optical imaging In vivo Optical imaging Image resolution Biopsy Visualization Biological tissues

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Eliminate self-interference misses of cache through modifying data layout of arrays 4

Eliminate self-interference misses of cache through modifyin...

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4th International Conference/Exhibition on high performance Computing in the Asia-Pacific Region, HPC-Asia 2000

作者： Lu, Xinda Chen, Jie High Performance Computing Laboratory Department of Computer Science and Engineering Shanghai Jiao Tong University Shanghai200030 China

ISBN: (纸本)0769505902

Loop tiling is an effective way to improve the cache hit ratio. However, while eliminating self-interference misses, tiling may produce small tiling factors for the cases of some arrays. In order to obtain stable and proper tiling factors, a new method that automatically generates tiling factors is proposed in this paper. These tiling factors are independent of arrays and can completely eliminate self-interference misses and can also significantly reduce cross-interference misses. © 2000 IEEE.

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Use of performance technology for the management of distributed systems 6

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6th International European Conference on Parallel Computing, Euro-Par 2000

作者： Kerbyson, Darren J. Harper, John S. Papaefstathiou, Efstathios Wilcox, Daniel V. Nudd, Graham R. High Performance Systems Laboratory Department of Computer Science University of Warwick United Kingdom Microsoft Research Cambridge United Kingdom

ISBN: (纸本)9783540679561

This paper describes a toolset, PACE, that provides detailed predictive performance information throughout the implementation and execution stages of an application. It is structured around a hierarchy of performance models that describes distributed computing systems in terms of its software, parallelisation and hardware components, providing performance information concerning expected execution time, scalability and resource use of applications. A principal aim of the work is to provide a capability for rapid calculation of relevant performance numbers without sacrificing accuracy. The predictive nature of the approach provides both pre- and post- implementation analyses, and allows implementation alternatives to be explored prior to the commitment of an application to a system. Because of the relatively fast analysis times, these techniques can be used at run-time to assist in application steering and efficient management of the available system resources. © Springer-Verlag Berlin Heidelberg 2000.

关键词： Application programs

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Nanothreads vs. Fibers for the support of fine grain parallelism on windows NT/2000 platforms

Nanothreads vs. Fibers for the support of fine grain paralle...

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3rd International Symposium on high performance Computing, ISHPC 2000

作者： Barekas, Vasileios K. Hadjidoukas, Panagiotis E. Polychronopoulos, Eleftherios D. Papatheodorou, Theodore S. High Performance Information Systems Laboratory Department of Computer Engineering and Informatics University of Patras Rio Patras26500 Greece

ISBN: (纸本)9783540411284

Support for parallel programming is very essential for the efficient utilization of modern multiprocessor systems. This paper focuses on the implementation of multithreaded runtime libraries used for the fine-grain parallelization of applications on the Windows 2000 operating system. We have implemented and introduce two runtime libraries. The first one is based on standard Windows user-level fibers, while the second is based on nanothreads. Both follow the Nanothreads Programming Model. A systematic evaluation comparing both implementations has also been conducted in three levels: the user-level thread packages, the runtime libraries and the applications level. The results demonstrate that nanothreads outperform the Windows fibers. The performance gains of the thread creation and context switching mechanisms are reflected on both runtime libraries. Experiments with fine-grain applications demonstrate up to 40% higher speedup in the case of nanothreads compared to that of fibers. © Springer-Verlag Berlin Heidelberg 2000.

关键词： Fibers

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