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1999 Internet Workshop, IWS 1999

作者： Kanchanasut, Kanchana Yamaguchi, Suguru Kiatsirivatana, Kriengsak Inoue, Hiroyuki Suksakorn, Apisit Tantatsanawong, Panjai Internet Research Lab Computer Science and Information Management Program School of Advanced Technologies Asian Institute of Technology P.0.Box 4. KIongluang Pathumthani12120 Thailand Graduate School of Information Science Nara Institute of Science and Technology 8916-5 Takayama Ikoma Nara630-0101 Japan

ISBN: (纸本)0780359259

Hierarchical WWW cache formation which provides both higher hit rates and saves overall bandwidth consumption through fetching WWW objects and periodically redistributing them among member caches is proposed as an application on a satellite Internet infrastructure. With regular prefetching and distribution of WWW objects, our system can utilize the satellite Internet with continuous streaming data transmissions for efficient WWW caching. Our system consists of a single hub cache and several rim caches. The hub cache is a core unit which is located at the satellite hub station and gathers WWW objects from the Internet, while the rim cache fetches requested WWW objects from the hub cache as well as receiving WWW objects pushed from the hub cache. The prefetching strategy of the rim cache is based on the statistical pattern analysis of user accesses. Traffic monitoring is used to manage both prefetching and object push operations. In order to reduce the consumption of bandwidth in the satellite Internet, multicast transmission of WWW objects is introduced. Furthermore, cached objects are checked regularly with an ''if update' tag so that their consistency can be maintained with reasonable overhead. We discuss our design and implementation of the AI3 CacheBone with our adaptive hierarchical WWW cache formation scheme. Through experiments, we show that the performance of our rim cache shows an improvement of approximately three fold when compared with ordinary hierarchical cache systems such as Squid. © 1999 IEEE.

关键词： Bandwidth

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Rare failure-state in a Markov chain model for software reliability

Rare failure-state in a Markov chain model for software reli...

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International Symposium on Software Reliability Engineering (ISSRE)

作者： M.G. Thomason J.A. Whittaker Department of Computer Science University of Tennessee Knoxville TN USA Computer Science Program Florida Institute of Technology Melbourne FL USA

Software systems composed of highly reliable components may experience few, if any, failures while undergoing heavy testing or field usage. L.M. Kaufman et al. (1997, 1998) applied "statistics of the extremes" to software reliability analysis for failure as an infrequent, unlikely occurrence /sub -/ /sub a/ so-called rare event. This paper combines (i) software failure as a rare event with (ii) a finite-state, discrete-parameter recurrent Markov chain that models both the failures (as transitions to a rare fail state) and the software usage probabilities (as transitions among usage states not involving the fail state). When conditions for rare events are met, reliability analysis in greater detail, with fewer assumptions, may be possible, and there may be additional justification for using the popular Poisson and exponential distributions for certain random variables. We describe how the Markov chain and the "Poisson law of small numbers", which has a central role in the study of rare events and extreme values, yield (a) an explicit error bound on a Poisson approximation for counts of failures as rare events in long realizations of the chain, and (b) an approximate exponential distribution for the interoccurrence time of failures as rare events. We compute both the Poisson error bound and /spl chi//sup 2/ goodness-of-fit tests for samples and the approximate distributions for a small Markov chain. A typical application of these results would be in the analysis of software reliability for systems of high-quality COTS components.

关键词： Software reliability computer science Statistical analysis Failure analysis Application software System testing Reactive power Random variables Reliability theory Statistics

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Synthesis and design of a 6th order SC lowpass decimator combining externally and internally cascaded structures 1

Synthesis and design of a 6th order SC lowpass decimator com...

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1st IEEE Asia Pacific Conference on ASICs, AP-ASIC 1999

作者： Cheong, Ngai Martins, R.P. Computer Studies Program Macau Polytechnic Institute Estrada D Maria II Edificio CEM 8/F China Faculty of Science and Technology University of Macau P.O. Box 3001 China

ISBN: (纸本)0780357051

This paper proposes an interactive architecture compiler for SC multirate circuits, here applied to the design of multistage IIR SC decimators with large decimating factors M. This methodology is implemented based on multi-decimation building blocks such as externally cascaded, internally cascaded or ladder building blocks. A computer-based design is carried out to synthesize and evaluate the performances of the corresponding resulting circuits, in order to achieve the required anti-aliasing amplitude responses, to relax the speed requirements of the operational amplifiers, and also to reduce the capacitance spread and total capacitor area. A design example of a 6th order SC elliptic decimator with M=10 is given to illustrate the above methodology. © 1999 IEEE.

关键词： Anti-aliasing

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Synthesis and design of a 7/sup th/ order SC lowpass decimator combining externally cascaded and ladder structures

Synthesis and design of a 7/sup th/ order SC lowpass decimat...

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IEEE Workshop on Signal Processing Systems (SIPS)

作者： Cheong Ngai R.P. Martins Computer Studies Program Macao Polytechnic Institute Macao China Faculty of Science and Technology University of Macau Macao China

This paper proposes a computer-automated synthesis of SC decimators with a high decimating factor based on the statistical approach of the program (ISCMRATE). This methodology is implemented based on multi-decimation building blocks, such as externally cascaded, internally cascaded or ladder structures and polyphase input networks. The design criteria are given to obtain and evaluate the performance of the corresponding resulting circuits. A design example of a 7/sup th/ order SC lowpass elliptic decimator with M=10 is given to illustrate the above proposed methodology.

关键词： Sampling methods Capacitance Capacitors IIR filters Network synthesis Prototypes Circuit topology Circuit simulation Frequency response Design methodology

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Synthesis and design of a 6th order SC lowpass decimator combining externally and internally cascaded structures

Synthesis and design of a 6th order SC lowpass decimator com...

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IEEE Asia-Pacific Conference on ASIC (AP-ASIC)

作者： Ngai Cheong R.P. Martins Computer Studies Program Macao Polytechnic Institute Macao China Faculty of Science and Technology University of Macau Macao China

关键词： Capacitance Capacitors Passband IIR filters Circuit synthesis Poles and zeros Circuit topology Cutoff frequency Design methodology Design optimization

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Proximal femoral density patterns are consistent with bicentric joint loads

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computer Methods in Biomechanics and Biomedical Engineering 1999年第4期2卷 271-283页

作者： Fischer, Kenneth J. Jacobs, Christopher R. Levenston, Marc E. Cody, Dianna D. Carters, Dennis R. Musculoskeletal Research Center Department of Orthopaedic Surgery University of Pittsburgh Pittsburgh PA 15213 United States Department of Orthopaedics Musculoskeletal Research Laboratory Pennsylvania State University School of Medicine Hershey PA 17033 United States Department of Electrical Engineering and Computer Science Continuum Elect romechanics Mhoratory Massachusetts Institute of Technology Hershey MA 02139 United States Department of Diagnostic Radiology Division of Radiologic Physics and Engineering Henry Ford Hospital Detroit MI 48202 United States Department of Veterans Affairs Medical Center Rehabilitation Research and Development Center Palo Alto CA 94304-1200 United States Department of Mechanical Engineering Stanford University Biomechanical Engineering Program Stanford CA 94305-402 United States

We developed an alternate method for density-based load estimation and applied it to estimate hip joint load distributions for two femora. Two-dimensional finite element models were constructed from single energy quantitative computed tomography (QCT) data. Load estimation was performed using five loading regions on the femoral head. Within each loading region, individual nodal loads, normal to the local surface, were supplied as input to the load estimation. An optimization procedure independently adjusted individual nodal load magnitudes in each region, and the magnitudes of muscle forces on the greater trochanter, such that the applied tissue stimulus approached the reference stimulus throughout the model. Dominant estimated load resultant directions were generally consistent with published experimental data for loads during gait. The estimated loads also suggested that loads near the extremes of the articulating surface may be important (even required) for development and maintenance of normal bone architecture. Estimated load distributions within nearly all regions predicted bicentric loading patterns, which are consistent with observations of hip joint incongruity. Remodeling simulations with the estimated loads predicted density distributions with features qualitatively similar to the QCT data sets. This study illustrates how applications of density-based bone load estimation can improve understanding of dominant loading patterns in other bones and joints. The prediction of bicentric loading suggests a very fine level of local adaptation to details of joint loading. © 1999 OPA (Overseas Publishers Association) N.V.

关键词： Finite element method

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Modelling combat system manning and manpower reduction

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NAVAL ENGINEERS JOURNAL 1999年第3期111卷 153-171页

作者： Roos, CH Carl H. Roos:is a Senior Engineer with Logicon-Syscon. A graduate of the University of Pittsburgh with a BSEE degree he has over 35 years experience in functional operational combat system fire control interface and computer program design. As technology changed and the combat system was upgraded Mr. Roos maintained his level of technical expertise by taking graduate-level courses in computer science modelling & structured analysis networking & fiber optics. He has worked in various capacities on the LHD LHA DDG 993 DD 963 LPD 17 LCC LPD 13 CGN 38 CGN 9 CG 26 and the DDG Class Combat Systems. In recent years Mr. Roos has been responsible for managing directing and performing engineering design and analysis efforts associated with Battle Management Organization (BMO) functional analysis and operational analysis. These efforts were used in defining combat system operational requirements shipboard space requirements and integration requirements. His paper “Configuration Management of Digital Programs” was published at the 1972 IEEE Southeastern Conrence.

NAVSEA 03K41 is responsible for generating Combat System Rattle Management Organizations (BMO) and Functional Flow Diagrams (FFD). Several years ago, NAVSEA provided the resources to conduct a functional analysis that would support the development and validation of the BMOs and FFDs. The major obstacle in performing the analysis was obtaining a consensus on how the functional hierarchy was to be structured. The non-optimum organization of the hierarchy was selected;as a result, the functions were difficult to define, find, use, and validate. Recognizing the shortcomings of this effort, research was conducted to evaluate state-of-the-art structured modelling techniques, concepts, and methodologies. Two modelling concepts by James Martin were found to be applicable for the combat system functional analysis: Enterprise Modelling Concept and Functional Decomposition Modelling Concept. The Structure Modelling definitions of Whitten, Bently, and Barlow provided the guidelines for using the Martin concepts. During the ensuing BMO and FFD development efforts, a Ship's Combat System (SCS) Modelling concept evolved and a SCS Model was developed. This paper addresses how the modelling concepts and tools are used in the BMO and FFD development and validation process. Data from the SCS Model provides the basis for defining combat system requirements (e.g., software, data display, database, networking, etc.).

关键词： Naval vessels

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A comparison of ada and pascal in an introductory computer science course 98

A comparison of ada and pascal in an introductory computer s...

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1998 Annual ACM SIGAda International Conference on Ada, SIGAda 1998

作者： Murtagh, Jeanne L. Hamilton, John A. Software Professional Development Program Air Force Institute of Technology Wright-Patterson AFBOH45433-7765 United States US Army D/Electrical Engineering and Computer Science United States Military Academy West PointNY10996-1787 United States

ISBN: (纸本)1581130333

Pascal's long and successful run at West Point illustrated Winston Churchill's dictum that, "The absence of alternatives clears the mind wonderfully." However, by the mid-90s, the United States Military Academy was finding that Pascal, long the educational workhorse, was no longer the clear choice for serious computer science education. The decision was taken to evaluate alternatives to Pascal. The criteria selected for programming language evaluation were student learning outcomes based on course goals and objectives. The controlled educational environment of a service academy provides an excellent opportunity to conduct research using control groups and experimental groups. We conducted a side by side comparison of the use of Pascal, which was specifically designed for instructional purposes, and Ada in an introductory course. The experiment demonstrated that students were much more successful in Ada than in Pascal, and led to the revision of the Academy core curriculum to use Ada 95 in our introductory computer science class. This paper discusses the details of our comparison, citing specific examples to illustrate a rational basis for evaluating programming language features against course objectives.

关键词： Students

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Toward biomimetic oculomotor control

Toward biomimetic oculomotor control

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IEEE International Workshop on Intelligent Robots and Systems (IROS)

作者： T. Shibata S. Schaal Kawato Dynamic Brain Project ERATO Japan Science and Technology Corporation (JST) Kyoto Japan Department of Computer Science and Neuroscience Program University of Southern California USA

Oculomotor control is the foundation of most biological visual systems, as well as an important component in the entire perceptual-motor system. We review some of the most basic principles of biological oculomotor systems, and explore their usefulness from both the biological and computational point of view. As an example of biomimetic oculomotor control, we present the state of our implementations and experimental results using the vestibulo-ocular-reflex and opto-kinetic-reflex paradigm.

关键词： Biomimetics Control systems Biological control systems Visual system Biology computing Motor drives Machine vision Circuit synthesis Control system synthesis Tiles

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A new estimation formula for minimum filter length of optimum FIR digital filters

A new estimation formula for minimum filter length of optimu...

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International Conference on Signal Processing Proceedings (ICSP)

作者： K. Ichige M. Iwaki R. Ishii Doctoral Program in Engineering University of Tsukuba Tsukuba Ibaraki Japan Japan Advanced Institute of Science and Technology Tatsunokuchi Ishikawa Japan Division of Electrical and Computer Engineering Yokohama National University Yokohama Japan

This paper presents an accurate estimation formula for the minimum filter length of optimum (the minimax criterion-based) FIR low-pass digital filters. The authors have proposed an accurate estimation formula for the particular case that the passband and stopband ripples are identical. Now we expand the formula for the general case. The accuracy of the proposed formula is evaluated in comparison with that of the conventional formulae. We also describe how to apply the proposed formula for the design of other types of filters.

关键词： Digital filters Finite impulse response filter Low pass filters Design optimization Algorithm design and analysis Iterative algorithms Passband Cutoff frequency Minimax techniques Iterative methods

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