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The French history of computing scene: The 80th Public Meeting of the computer Conservation Society, London, 8 December 2005

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IEEE ANNALS OF THE HISTORY OF COMPUTING 2006年第2期28卷 63-67页

作者： Anderson, David Kansai Univ Suita Osaka Japan

Information about the topics discussed at the 80th public meeting of the computer Conservation Society on December 8, 2005 at London Science Museum in England is presented. The meeting focused on the history of French computing devices. It tackled calculating machines and punched cards like Pascal, the Arithmometer of Thomas de Colmar and tables of logarithms of de Prony's. It gave insights on the story of the French software industry which developed various mathematical tools. It also honored the Association for an Academy of Data Processing and Telematics for being responsible in preserving the computing heritage in France. The meeting featured the members of the computer Conservation Society, Philippe Denoyelle and Hans Paufal, as speakers.

关键词： CONFERENCES & conventions PUNCHED card systems computer software industry computer algorithms CALCULATORS PUBLIC meetings PASCAL (computer program language) LOGARITHMS

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computer simulations of the ROUSE model: An analytic simulation technique and a comparison between the error variance-covariance and bootstrap methods for estimating parameter confidence

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BEHAVIOR RESEARCH METHODS 2006年第4期38卷 557-568页

作者： Huber, David E. Univ Calif San Diego Dept Psychol La Jolla CA 92093 USA

This article provides important mathematical descriptions and computer algorithms in relation to the responding optimally with unknown sources of evidence (ROUSE) model of Huber, Shiffrin Lyle, and Ruys (2001), which has been applied to short-term prindng phenomena. In the first section, techniques for obtaining parameter confidence intervals and parameter correlations are described, which are generally applicable to any mathematical model. In the second section, a technique for producing analytic ROUSE predictions is described. Huber et al. (2001) averaged many stochastic trials to obtain stable behavior. By appropriately weighting all possible combinations of feature states, an alternative analytic version is developed, yielding asymptotic model behavior with fewer computations. The third section ties together these separate techniques, obtaining parameter confidence and correlations for the analytic version of the ROUSE model. In doing so, previously unreported behaviors of the model are revealed. In particular, complications due to local minima are discussed, in terms of both variance-covariance analyses and bootstrap sampling analyses.

关键词： computer simulation MATHEMATICAL models computer algorithms RESEARCH -- Methodology BEHAVIORAL research

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Constant hardware delay in integrated switching elements with multiserver output queues

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IEE PROCEEDINGS-COMMUNICATIONS 2006年第5期153卷 664-670页

作者： De Schepper, B. Steyaert, B. Wittevrongel, S. Moeneclaey, M. Bruneel, H. Univ Ghent Dept Telecommun & Informat Proc Stochast Modeling & Anal Commun Syst Res Grp B-9000 Ghent Belgium Univ Ghent Dept Telecommun & Informat Proc Digital Commun Res Grp B-9000 Ghent Belgium

The authors consider an integrated switching element with a shared buffer memory and a constant hardware delay. This hardware delay is caused by the hardware operations required to process the routing information of incoming cells. A general uncorrelated cell arrival process in the switch, an independent and uniform routing process of cells from the inlets to the outlets of the switch and a first-come-first-served queueing discipline are assumed. The performance of the switching element is evaluated by means of an analytical technique based on an extensive use of probability generating functions. Explicit expressions for the probability generating functions, the mean values, the variances and the tail probabilities of the occupancy and the cell delay of the switch are obtained. Numerical examples show that the hardware delay has an important impact on the switch performance.

关键词： computer input-output equipment computer algorithms PERFORMANCE evaluation PROBABILITY theory MATHEMATICAL analysis SWITCHING circuits ROUTING (computer network management) GENERATING functions

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Ab initio molecular dynamics with discrete variable representation basis sets: Techniques and application to liquid water

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JOURNAL OF PHYSICAL CHEMISTRY A 2006年第16期110卷 5549-5560页

作者： Lee, HS Tuckerman, ME NYU Dept Chem New York NY 10003 USA NYU Courant Inst Math Sci New York NY 10003 USA

Finite temperature ab initio molecular dynamics (AIMD), in which forces are obtained from "on-the-fly" electronic structure calculations, is a widely used technique for studying structural and dynamical properties of chemically active systems. Recently, we introduced an AIMD scheme based on discrete variable representation (DVR) basis sets, which was shown to have improved convergence properties over the conventional plane wave (PW) basis set [Liu,Y.;et al. Ph)u. Rev. B 2003, 68, 125110]. In the present work, the numerical algorithms for the DVR based AIMD scheme (DVR/AIMD) are provided in detail, and the latest developments of the approach are presented. The accuracy and stability of the current implementation of the DVR/AIMD scheme are tested by performing a simulation of liquid water at ambient conditions. The structural information obtained from the present work is in good agreement with the result of recent AIMD simulations with a PW basis set (PW/AIMD). Advantages of using the DVR/AIMD scheme over the PW/AIMD method are discussed. In particular, it is shown that a DVR/AIMD simulation of liquid water in the complete basis set limit is possible with a relatively small number of grid points.

关键词： BASIS sets (Quantum mechanics) MOLECULAR dynamics WATER ELECTRONIC structure SIMULATION methods & models computer algorithms AIMD algorithms

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Deterministic broadcast and gossiping algorithms for ad hoc networks

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JOURNAL OF SUPERCOMPUTING 2006年第2期37卷 115-144页

作者： Sinha, Koushik Srimani, Pradip K. Clemson Univ Dept Comp Sci Clemson SC 29634 USA

We present in this paper three deterministic broadcast and a gossiping algorithm suitable for ad hoc networks where topology changes range from infrequent to very frequent. The proposed algorithms are designed to work in networks where the mobile nodes possessing collision detection capabilities. Our first broadcast algorithm accomplishes broadcast in O(nlog n) for networks where topology changes are infrequent. We also present an O(nlog n) worst case time broadcast algorithms that is resilient to mobility. For networks where topology changes are frequent, we present a third algorithm that accomplishes broadcast in O(triangle center dot n log n+n center dot vertical bar M vertical bar) in the worst case scenario, where vertical bar M vertical bar is the length of the message to be broadcasted and triangle the maximum node degree. We then extend one of our broadcast algorithms to develop an O(Dn log n + D-2) algorithm for gossiping in the same network model.

关键词： MOBILE communication systems BROADCASTING industry RADIO networks computer algorithms TELECOMMUNICATION systems computer networks TOPOLOGY ELECTRONIC systems TELECOMMUNICATION INFORMATION technology

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Tulip: A new hash based cooperative web caching architecture

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JOURNAL OF SUPERCOMPUTING 2006年第3期35卷 301-320页

作者： Xu, ZY Bhuyan, L Hu, YM Suffolk Univ CS Dept Boston MA 02108 USA Univ Calif Riverside CSE Dept Riverside CA 92521 USA Univ Cincinnati ECECS Dept Cincinnati OH 45221 USA

With the exponential growth of WWW traffic, web proxy caching becomes a critical technique for Internet web services. Well-organized proxy caching systems with multiple servers can greatly reduce the user perceived latency and decrease the network bandwidth consumption. Thus, many research papers focused on improving web caching performance with the efficient coordination algorithms among multiple servers. Hash based algorithm is the most widely used server coordination mechanism, however, there's still a lot of technical issues need to be addressed. In this paper, we propose a new hash based web caching architecture, Tulip. Tulip aggregates web objects that are likely to be accessed together into object clusters and uses object clusters as the primary access units. Tulip extends the locality-based algorithm in UCFS to hash based web proxy systems and proposes a simple algorithm to reduce the data grouping overhead. It takes into consideration the access speed dispatch between memory and disk and replaces expensive small disk I/O with less large ones. In case a client request cannot be fulfilled by the server in the memory, the system fetches the whole cluster which contains the required object into memory, the future requests for other objects in the same cluster can be satisfied directly from memory and slow disk I/Os are avoided. It also introduces a simple and efficient data dupllication algorithm, few maintenance work need to be done in case of server join/leave or server failure. Along with the local caching strategy, Tulip achieves better fault tolerance and load balance capability with the minimal cost. Our simulation results show Tulip has better performance than previous approaches.

关键词： WORLD Wide Web CACHE memory WEB services ONLINE information services computer algorithms computer architecture WEB servers COMMUNICATIONS industries computer input-output equipment

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Building small equality graphs for deciding equality logic with Uninterpreted Functions

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INFORMATION AND COMPUTATION 2006年第1期204卷 26-59页

作者： Rodeh, Y Strichman, O Technion Israel Inst Technol Haifa Israel Tel Hai Coll Tel Hai Israel

The logic of equalities with Uninterpreted Functions is used in the formal verification community mainly for proofs of equivalence: proving that two versions of a hardware design are the same, or that input and output of a compiler are semantically equivalent are two prominent examples of such proofs. We introduce a new decision procedure for this logic that generalizes two leading decision procedures that were published in the last few years: the Positive Equality approach suggested by Bryant et al. [Exploiting positive equality in a logic of equality with uninterpreted functions, in: Proc. 11th Intl. Conference on computer Aided Verification (CAV'99), 1999], and the Range-Allocation algorithm suggested by Pnueli et al. [The small model property: how small can it be? Information and Computation 178 (1) (2002) 279-293]. Both of these methods reduce this logic to pure Equality Logic (without Uninterpreted Functions), and then, due to the small model property that such formulas have, find a small domain to each variable that is sufficiently large to maintain the satisfiability of the formula. The state-space spanned by these domains is then traversed with a BDD-based engine. The Positive Equality approach identifies terms that have a certain characteristic in the original formula (before the reduction to pure Equality Logic), and replaces them with unique constants. The Range-Allocation algorithm analyzes the structure of the formula after the reduction to equality logic with a graph-based procedure to allocate a small set of values to each variable. The former, therefore, has an advantage when a large subset of the terms can be replaced with constants, and disadvantage in the other cases. In this paper we essentially merge the two methods, while improving both with a more careful analysis of the formula's structure. We show that the new method is provably dominant over both methods, theoretically as well as empirically. (c) 2005 Elsevier Inc. All rights reserved.

关键词： algorithms computer algorithms SEMANTICS -- Network analysis HARDWARE

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Optimal implicit dictionaries over unbounded universes

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THEORY OF COMPUTING SYSTEMS 2006年第2期39卷 321-345页

作者： Franceschini, G Grossi, R Univ Pisa Dipartimento Informat I-56127 Pisa Italy

An array of n distinct keys can be sorted for logarithmic searching or can be organized as a heap for logarithmic updating, but it is unclear how to attain logarithmic time for both searching and updating. This natural question dates back to the heap of Williams and Floyd in the sixties and relates to the fundamental issue whether additional space besides those for the keys gives more computational power in dictionaries and how data ordering helps. Implicit data structures were introduced in the eighties with this goal, providing the best bound of O(log(2) n) time. until a recent result showing O(log(2) n/log log n) time. In this paper we describe the flat implicit tree, which is the first data structure obtaining O(log n) time for search and (amortized) update using an array of n cells.

关键词： COMPUTATIONAL complexity DATA structures (computer science) FILE organization (computer science) computer algorithms LOGARITHMS computer systems

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Progressive Multi Gray-Leveling: A voice spam protection algorithm

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IEEE NETWORK 2006年第5期20卷 18-24页

作者： Shin, Dongwook Ahn, Anyoung Shim, Choon Towson State Univ Towson MD USA

As voice over IP gains popularity, it is easy to imagine that Internet hacking and other security problems we currently face with email spam will attack the VoIP environment. In contrast to email protocols represented by SMTP, VoIP does not tolerate any negotiation in its signaling steps or screening content due to the delay limitation. Thus, it is difficult to implement voice spam protection or control algorithms by just mimicking popular email spam protection algorithms. This article proposes a voice spam control algorithm called Progressive Multi Gray-Leveling (PMG) that fits in VoIP settings. PMG progressively calculates the "gray level" of a caller and determines whether the call will be connected or blocked based on previous call patterns. Based on experiments, it turns out that PMG can learn a spammer's calling pattern and block massive spam attacks from them effectively.

关键词： INTERNET telephony computer security VOICE mail systems computer algorithms DATA transmission systems TELEPHONE systems ACCESS control FILTERING software DIGITAL telephone systems

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Decentralized control of tall buildings

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STRUCTURAL DESIGN OF TALL AND SPECIAL BUILDINGS 2006年第2期15卷 153-170页

作者： Rofooei, FR Monajemi-Nezhad, S Sharif Univ Technol Dept Civil Engn Tehran Iran

The response of large-scale building structures can be actively reduced using an appropriate control algorithm and a number of actuators and sensors located within the building. This paper presents a decentralized control approach for controlling the response of tall buildings. The proposed method aims to divide the structural model into several substructures, each one performing on its own controller algorithm. This approach has already been used in controlling large-scale systems such as power transmission systems and space structures. An instantaneous optimal control scheme is used as the control algorithm with different control feedbacks such as velocity feedback alone and displacement and velocity feedback. The stability issue of this method is addressed. A numerical example is used to investigate the performance of the proposed method compared to the case with centralized control. Copyright (c) 2005 John Wiley & Sons, Ltd.

关键词： actuators Standing Orders Structural Models Substructures numerical example computer algorithms Decentralized Buildings power transmission system INTEGRATED SHIP CONTROL velocity feedback decentralised control control response

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