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Discrete-time fuzzy sliding mode control for a vehicle suspension system featuring an electrorheological fluid damper

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SMART MATERIALS AND STRUCTURES 2007年第3期16卷 798-808页

作者： Sung, Kum-Gil Han, Young-Min Lim, Kye-Hyun Choi, Seung-Bok Inha Univ Dept Mech Engn Smart Struct & Syst Lab Inchon 402751 South Korea

This paper presents real-time control characteristics of an electrorheological (ER) suspension system via a fuzzy sliding mode control algorithm which is formulated in a discrete-time manner by considering the sampling rate of an electronic control unit for a vehicle system. A quarter-vehicle system consisting of sprung mass, spring, tire and a cylindrical ER damper (shock absorber) is constructed for the real-time control. After deriving the governing equation of motion of the proposed system, a discrete-time control model with system uncertainties is formulated. A stable sliding surface is then designed and followed by the formulation of the discrete-time sliding mode controller which consists of a discontinuous part and an equivalent part. In the controller formulation, the fuzzy control algorithm is also adopted to enhance system robustness to the mass variation and reaching time to the sliding surface. The controller is then experimentally realized for the manufactured quarter-vehicle ER suspension system. Control performances such as vertical acceleration are evaluated under various road conditions and presented in both time and frequency domains.

关键词： Slip surfaces Pavement condition Suspension System normal acceleration computer algorithms time monitoring Governing equation Erbium Equations of motion Controllers fuzzy sliding mode control system uncertainties discrete-time electronic control unit Real time control

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An analysis of the compositional techniques in John!Chowning's Stria

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computer MUSIC JOURNAL 2007年第3期31卷 26-37页

作者： Meneghini, Matteo Univ Padua I-35131 Padua Italy

This article describes an analytic study of the process used by John Chowning for the composition of Stria. This article is intended to complete the description of the compositional process given in a previous work (Meneghini 2003), largely restated by Bossis in a subsequent paper (Bossis 2005). Stria was composed in 1977 and was fully generated by means of computer algorithms (Chowning 1977c) and the corresponding input files (Chowning 1977a, b): all the parameters of the sounds generated in Stria are determined and calculated by these algorithms on the basis of specific mathematical rules and of numerical parameters chosen by Mr. Chowning as input for the programs. For this reason, an accurate analysis of these algorithms is fundamental for a complete comprehension of the compositional process.

关键词： computer algorithms computer programming computer music ELECTRONIC music SOUND recordings PROGRAMMING languages (Electronic computers) ELECTRONIC data processing computer programmers

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Novel data association schemes for the probability hypothesis density filter

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IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS 2007年第2期43卷 556-570页

作者： Panta, Kusha Vo, Ba-Ngu Singh, Sumeetpal Univ Melbourne Co Operat Res Ctr Sensor & Informat Proc Dept Elect & Elect Engn Melbourne Vic 3010 Australia Univ Melbourne Dept Elect & Elect Engn Cambridge CB2 1PZ England

The probability hypothesis density (PHD) filter is a practical alternative to the optimal Bayesian multi-target filter based on finite set statistics. It propagates the PHD function, a first-order moment of the full multi-target posterior density. The peaks of the PHD function give estimates of target states. However, the PHD filter keeps no record of target identities and hence does not produce track-valued estimates of individual targets. We propose two different schemes according to which PHD filter can provide track-valued estimates of individual targets. Both schemes use the probabilistic data-association functionality albeit in different ways. In the first scheme, the outputs of the PHD filter are partitioned into tracks by performing track-to-estimate association. The second scheme uses the PHD filter as a clutter filter to eliminate some of the clutter from the measurement set before it is subjected to existing data association techniques. In both schemes, the PHD filter effectively reduces the size of the data that would be subject to data association. We consider the use of multiple hypothesis tracking (MHT) for the purpose of data association. The performance of the proposed schemes are discussed and compared with that of MHT.

关键词： PROBABILITY measures TRACKING radar HYPOTHESIS STATISTICS DENSITY functionals computer algorithms GAUSSIAN processes RADIO filters ELECTRONICS

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Generating referring expressions: Making referents easy to identify

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COMPUTATIONAL LINGUISTICS 2007年第2期33卷 229-254页

作者： Paraboni, Ivandre van Deemter, Kees Masthoff, Judith Univ Sao Paulo EACH BR-05508 Sao Paulo Brazil Univ Aberdeen Dept Comp Sci Aberdeen AB9 1FX Scotland

It is often desirable that referring expressions be chosen in such a way that their referents are easy to identify. This article focuses on referring expressions in hierarchically structured domains, exploring the hypothesis that referring expressions can be improved by including logically redundant information in them if this leads to a significant reduction in the amount of search that is needed to identify the referent, Generation algorithms are presented that implement this idea by including logically redundant information into the generated expression, in certain well-circumscribed situations. To test our hypotheses, and to assess the performance of our algorithms, two controlled experiments with human subjects were conducted. The first experiment confirms that human judges have a preference for logically redundant expressions in the cases where our model predicts this to be the case. The second experiment suggests that readers benefit from the kind of logical redundancy that our algorithms produce, as measured in terms of the effort needed to identify the referent of the expression.

关键词： COMPUTATIONAL linguistics computer algorithms REDUNDANCY (Linguistics) INFORMATION science -- Study & teaching APPLIED linguistics STRUCTURAL linguistics LINGUISTICS -- Research

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An exact subexponential-time lattice algorithm for Asian options

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ACTA INFORMATICA 2007年第1期44卷 23-39页

作者： Dai, Tian-Shyr Lyuu, Yuh-Dauh Natl Taiwan Univ Dept Comp Sci & Informat Engn Taipei 106 Taiwan Natl Chiao Tung Univ Dept Informat & Finance Management Hsinchu 300 Taiwan

Asian options are popular financial derivative securities. Unfortunately, no exact pricing formulas exist for their price under continuous-time models. Asian options can also be priced on the lattice, which is a discretized version of the continuous- time model. But only exponential-time algorithms exist if the options are priced on the lattice without approximations. Although efficient approximation methods are available, they lack accuracy guarantees in general. This paper proposes a novel lattice structure for pricing Asian options. The resulting pricing algorithm is exact (i.e., without approximations), converges to the value under the continuous-time model, and runs in subexponential time. This is the first exact, convergent lattice algorithm to break the long-standing exponential-time barrier.

关键词： INFORMATION science -- Research computer science MATHEMATICAL programming OPTIONS (Finance) DERIVATIVE securities computer algorithms PRICING

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Simultaneous tracking and classification: A modularized scheme

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IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS 2007年第2期43卷 581-599页

作者： Mei, Wei Shan, Gan-Lin Li, X. Rong Shijiazhuang Mech Engn Coll Dept Elect Engn Shijiazhuang 050003 Peoples R China Univ New Orleans Dept Elect Engn New Orleans LA 70148 USA

The high computational complexity of existing joint tracking and classification (JTC) algorithms hampers their application. After presenting a new description of the JTC problem-simultaneous tracking and classification (STC) instead of JTC, we derive two STC algorithms in both exact and approximate forms by applying Bayes' rule to the target state probability density function (pdf) and target class probability mass function (pmf) simultaneously under the assumption that the kinematic and attribute measurement processes are conditional independent. The mutual information exchange between tracker and classifier of the proposed STC algorithms is introduced by defining the simultaneous pdf-pmf of target state and class, the dependence of kinematic measurement on target class, the dependence of attribute measurement on target state and target model, class-dependent kinematic model sets, and class-dependent flight envelopes, etc. The proposed STC algorithms have four distinctive features. First, they have a modularized structure, i.e., they explicitly integrate a multiple-model filter and a Bayesian classifier. Second, the approximate versions, which follow easily from the proposed STC algorithms thanks to their modularized structure, have a closed form with a lower computational complexity and are more suitable for real-time applications. Third, the proposed exact STC algorithms are derived without the hidden approximation made in some existing multiple-model based JTC algorithms. Fourth, one of the proposed STC algorithms has the potential to further reduce the computational load since it has no redundant motion models. Simulation results suggest that the proposed STC algorithms provide a hopeful solution to a class of STC problems.

关键词： BAYESIAN analysis computer algorithms DENSITY functionals RADAR targets ARTIFICIAL satellite tracking KALMAN filtering ELECTRONIC measurements DETECTORS GAUSSIAN processes

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On Abelian 2-avoidable binary patterns

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ACTA INFORMATICA 2007年第8期43卷 521-533页

作者： Currie, James D. Visentin, Terry I. Univ Winnipeg Dept Math & Stat Winnipeg MB R3B 2E9 Canada

We give the first example of a binary pattern which is Abelian 2-avoidable, but which contains no Abelian fourth power. We introduce a family {fn}(n=1)(infinity) of binary morphisms which offer a common generalization of the Fibonacci morphism and the Abelian fourth-power-free morphism of Dekking. We show that the Fibonacci word begins with arbitrarily high Abelian powers, but for n >= 2, the fixed point of f(n) avoids x(n+2) in the Abelian sense. The sets of patterns avoided in the Abelian sense by the fixed points of f(n) and f(n+1) are mutually incomparable for n >= 2.

关键词： computer programming MORPHISMS (Mathematics) CATEGORIES (Mathematics) SET theory ABELIAN functions computer algorithms

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Spatial error concealment method based on POCS with a correlation-based initial block

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IET IMAGE PROCESSING 2007年第2期1卷 134-140页

作者： Kim, M. Lee, S.-W. Kim, S.-D. Korea Adv Inst Sci & Technol Dept EE&CS Div EE Taejon 305701 South Korea

A spatial error concealment method is proposed based on projections onto convex sets (POCS) with a correlation-based initial block. The conventional POCS results heavily depend on an initial block. To cope with this problem, a part of correctly received coefficients is utilised to find the most correlated neighbouring block, and a proper initial block is estimated from the found neighbouring block. The experiment shows that the proposed method has a much better performance.

关键词： ERRORS MULTIMEDIA communications PROJECTION PIXELS IMAGE processing computer algorithms

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Concept for facilitating analyst-mediated interpretation of qualitative chromatographic-mass spectral data: An alternative to manual examination of extracted ion chromatograms (vol 79, pg 4805, 2007)

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ANALYTICAL CHEMISTRY 2007年第17期79卷 6894-6894页

作者： Borges, Chad R. Sports Medicine Research and Testing Laboratory Department of Pharmacology & Toxicology University of Utah Salt Lake City Utah 84108

A chemometrics-based data analysis concept has been developed as a substitute for manual inspection of extracted ion chromatograms (XICs), which facilitates rapid, analyst-mediated interpretation of GC- and LC/MS⁽ⁿ⁾ data sets from samples undergoing qualitative batchwise screening for prespecified sets of analytes. Automatic preparation of data into two-dimensional row space-derived scatter plots (row space plots) eliminates the need to manually interpret hundreds to thousands of XICs per batch of samples while keeping all interpretation of raw data directly in the hands of the analystsaving great quantities of human time without loss of integrity in the data analysis process. For a given analyte, two analyte-specific variables are automatically collected by a computer algorithm and placed into a data matrix (i.e., placed into row space): the first variable is the ion abundance corresponding to scan number x and analyte-specific m/z value y, and the second variable is the ion abundance corresponding to scan number x and analyte-specific m/z value z (a second ion). These two variables serve as the two axes of the aforementioned row space plots. In order to collect appropriate scan number (retention time) information, it is necessary to analyze, as part of every batch, a sample containing a mixture of all analytes to be tested. When pure standard materials of tested analytes are unavailable, but representative ion m/z values are known and retention time can be approximated, data are evaluated based on two-dimensional scores plots from principal component analysis of small time range(s) of mass spectral data. The time-saving efficiency of this concept is directly proportional to the percentage of negative samples and to the total number of samples processed simultaneously.

关键词： ION exchange chromatography CHEMOMETRICS DATA analysis MASS spectrometry computer algorithms QUALITATIVE chemical analysis CHROMATOGRAPHIC analysis SPECTRUM analysis ANALYTICAL chemistry

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Fair ambients

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ACTA INFORMATICA 2007年第8期43卷 535-594页

作者： Fu, Yuxi Shanghai Jiao Tong Univ Dept Comp Sci BASICS Shanghai 200030 Peoples R China

Based on an analysis of the capability operators of the Calculus of Mobile Ambients, three fairness principles are proposed to safeguard the interactions of the ambients. The Calculus of Fair Ambient is designed to meet these fairness principles. A labeled transition semantics for the calculus is defined to support structural investigation. The bisimulation theory of the fair ambients is studied and two coincidence results are established. An expressiveness result of the calculus is formally established by proving that it contains the pi calculus as a sub-calculus.

关键词： computer algorithms RULE-based programming MATHEMATICAL analysis FUNCTIONS (Mathematics) CALCULUS

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