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29
Surrogate time series
 PHYSICA D
, 2000
"... Before we apply nonlinear techniques, e.g. those inspired by chaos theory, to dynamical phenomena occurring in nature, it is necessary to first ask if the use of such advanced techniques is justified by the data. While many processes in nature seem very unlikely a priori to be linear, the possible n ..."
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Cited by 161 (0 self)
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Before we apply nonlinear techniques, e.g. those inspired by chaos theory, to dynamical phenomena occurring in nature, it is necessary to first ask if the use of such advanced techniques is justified by the data. While many processes in nature seem very unlikely a priori to be linear, the possible nonlinear nature might not be evident in specific aspects of their dynamics. The method of surrogate data has become a very popular tool to address such a question. However, while it was meant to provide a statistically rigorous, foolproof framework, some limitations and caveats have shown up in its practical use. In this paper, recent efforts to understand the caveats, avoid the pitfalls, and to overcome some of the limitations, are reviewed and augmented by new material. In particular, we will discuss specific as well as more general approaches to constrained randomisation, providing a full range of examples. New algorithms will be introduced for unevenly sampled and multivariate data and for surrogate spike trains. The main limitation, which lies in the interpretability of the test results, will be illustrated through instructive case studies. We will also discuss some implementational aspects of the realisation of these methods in
Bitext Maps and Alignment via Pattern Recognition
 Computational Linguistics
, 1999
"... This article advances the state of the art ofbitext mapping by formulating the problem in terms of pattern recognition. From this point of view, the success of a bitext mapping algorithm hinges on how well it performs three tasks: signal generation, noise filtering, and search. The Smooth Injective ..."
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Cited by 104 (0 self)
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This article advances the state of the art ofbitext mapping by formulating the problem in terms of pattern recognition. From this point of view, the success of a bitext mapping algorithm hinges on how well it performs three tasks: signal generation, noise filtering, and search. The Smooth Injective Map Recognizer (SIMR) algorithm presented here integrates innovative approaches to each of these tasks. Objective evaluation has shown that SIMR's accuracy is consistently high for language pairs as diverse as French/English and Korean/English. If necessary, S IMR's bitext maps can be efficiently converted into segment alignments using the Geometric Segment Alignment (GSA) algorithm, which is also presented here. SIMR has produced bitext maps for over 200 megabytes of FrenchEnglish bitexts. GSA has converted these maps into alignments. Both the maps and the alignments are available from the Linguistic Data Consortium) 1.
Interdisciplinary application of nonlinear time series methods
 Phys. Reports
, 1998
"... This paper reports on the application to field measurements of time series methods developed on the basis of the theory of deterministic chaos. The major difficulties are pointed out that arise when the data cannot be assumed to be purely deterministic and the potential that remains in this situatio ..."
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Cited by 84 (4 self)
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This paper reports on the application to field measurements of time series methods developed on the basis of the theory of deterministic chaos. The major difficulties are pointed out that arise when the data cannot be assumed to be purely deterministic and the potential that remains in this situation is discussed. For signals with weakly nonlinear structure, the presence of nonlinearity in a general sense has to be inferred statistically. The paper reviews the relevant methods and discusses the implications for deterministic modeling. Most field measurements yield nonstationary time series, which poses a severe problem for their analysis. Recent progress in the detection and understanding of nonstationarity is reported. If a clear signature of approximate determinism is found, the notions of phase space, attractors, invariant manifolds etc. provide a convenient framework for time series analysis. Although the results have to be interpreted with great care, superior performance can be achieved for typical signal processing tasks. In particular, prediction and filtering of signals are discussed, as well as the classification of system states by means of time series recordings.
A Geometric Approach to Mapping Bitext Correspondence
, 1996
"... NLP work is to construct a detailed map of the correspondence between a text and its translation. Several auto matic methods for this task have been proposed in recent years. Yet even the best of these methods can err by several typeset pages. The Smooth Injective Map Recognizer (SIMR) is a new bit ..."
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Cited by 62 (13 self)
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NLP work is to construct a detailed map of the correspondence between a text and its translation. Several auto matic methods for this task have been proposed in recent years. Yet even the best of these methods can err by several typeset pages. The Smooth Injective Map Recognizer (SIMR) is a new bitext mapping algorithm. SIMR's errors are smaller than those of the previous frontrunner by more than a factor of 4. Its robustness has en abled new commercialquality applications. The greedy nature of the algorithm makes it independent of memory resources. Unlike other bitext mapping algorithms, SIMR allows crossing correspondences to account for word order differences. Its output can be converted quickly and easily into a sen tence alignment. SIMR's output has been used to align more than 200 megabytes of the Canadian Hansards for publication by the Linguistic Data Consortium.
Distributed Control by Lagrangian Steepest Descent
"... Often adaptive, distributed control can be viewed as an iterated game between independent players. The coupling between the players’ mixed strategies, arising as the system evolves from one instant to the next, is determined by the system designer. Information theory tells us that the most likely j ..."
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Cited by 23 (13 self)
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Often adaptive, distributed control can be viewed as an iterated game between independent players. The coupling between the players’ mixed strategies, arising as the system evolves from one instant to the next, is determined by the system designer. Information theory tells us that the most likely joint strategy of the players, given a value of the expectation of the overall control objective function, is the minimizer of a Lagrangian function of the joint strategy. So the goal of the system designer is to speed evolution of the joint strategy to that Lagrangian minimizing point, lower the expectated value of the control objective function, and repeat. Here we elaborate the theory of algorithms that do this using local descent procedures, and that thereby achieve efficient, adaptive, distributed control.
Shape modelling using markov random field restoration of point correspondences
 in Information Processing in Medical Imaging, LNCS 2732
, 2003
"... Abstract. A method for building statistical point distribution models is proposed. The novelty in this paper is the adaption of Markov random field regularization of the correspondence field over the set of shapes. The new approach leads to a generative model that produces highly homogeneous polygon ..."
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Cited by 20 (0 self)
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Abstract. A method for building statistical point distribution models is proposed. The novelty in this paper is the adaption of Markov random field regularization of the correspondence field over the set of shapes. The new approach leads to a generative model that produces highly homogeneous polygonized shapes and improves the capability of reconstruction of the training data. Furthermore, the method leads to an overall reduction in the total variance of the point distribution model. Thus, it finds correspondence between semilandmarks that are highly correlated in the shape tangent space. The method is demonstrated on a set of human ear canals extracted from 3Dlaser scans. 1
Metaheuristics: The state of the art
 LOCAL SEARCH FOR PLANNING AND SCHEDULING
"... Metaheuristics support managers in decisionmaking with robust tools that provide highquality solutions to important applications in business, engineering, economics and science in reasonable time horizons. In this paper we give some insight into the state of the art of metaheuristics. This prima ..."
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Cited by 20 (2 self)
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Metaheuristics support managers in decisionmaking with robust tools that provide highquality solutions to important applications in business, engineering, economics and science in reasonable time horizons. In this paper we give some insight into the state of the art of metaheuristics. This primarily focuses on the significant progress which general frames within the metaheuristics field have implied for solving combinatorial optimization problems, mainly those for planning and scheduling.
Spoken Document Retrieval Based on Phoneme Recognition
, 1998
"... Recently, vast amounts of audio and video material containing spoken information have become available in digital format, for example radio news recordings. Along with this development there is an increased demand to retrieve spoken information in response to a user's information need. This the ..."
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Cited by 19 (1 self)
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Recently, vast amounts of audio and video material containing spoken information have become available in digital format, for example radio news recordings. Along with this development there is an increased demand to retrieve spoken information in response to a user's information need. This thesis addresses the problem of spoken document retrieval (SDR). A particular goal is to perform experimental studies on documents spoken in German. The approach taken by this thesis requires a phoneme recognizer, which initially generates phoneme sequences from the spoken documents. The main issues of phonemerecognitionbased SDR are (1) missing word boundaries in the phoneme sequences and (2) the high number of phoneme recognition errors, requiring an errortolerant method to detect query words. We present Probabilistic String Matching (PSM); a new retrieval method where query words are spotted in document phoneme sequences that are corrupted by recognition errors. This method includes the detec...
Review of reactive power planning: objectives, constraints, and algorithms
 IEEE Transactions on Power Systems
"... Abstract—The key of reactive power planning (RPP), or Var planning, is the optimal allocation of reactive power sources considering location and size. Traditionally, the locations for placing new Var sources were either simply estimated or directly assumed. Recent research works have presented some ..."
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Abstract—The key of reactive power planning (RPP), or Var planning, is the optimal allocation of reactive power sources considering location and size. Traditionally, the locations for placing new Var sources were either simply estimated or directly assumed. Recent research works have presented some rigorous optimizationbased methods in RPP. This paper will first review various objectives of RPP. The objectives may consider many cost functions such as variable Var cost, fixed Var cost, real power losses, and fuel cost. Also considered may be the deviation of a given voltage schedule, voltage stability margin, or even a combination of different objectives as a multiobjective model. Secondly, different constraints in RPP are discussed. These different constraints are the key of various optimization models, identified as optimal power flow (OPF) model, securityconstrained OPF (SCOPF) model, and SCOPF with voltagestability consideration. Thirdly, the optimizationbased models will be categorized as conventional algorithms, intelligent searches, and fuzzy set applications. The conventional algorithms include linear programming, nonlinear programming, mixedinteger nonlinear programming, etc. The intelligent searches include simulated annealing, evolutionary algorithms, and tabu search. The fuzzy set applications in RPP address the uncertainties in objectives and constraints. Finally, this paper will conclude the discussion with a summary matrix for different objectives, models, and algorithms. Index Terms—Evolutionary algorithms (EAs), fuzzy sets, linear programming (LP), mixed integer nonlinear programming (MINLP), multiobjective optimization, nonlinear programming (NLP), OPF, reactive power optimal allocation, reactive power planning, simulated annealing (SA), securityconstrained OPF (SCOPF), security constrained OPF with voltagestability consideration (SCOPFVS), tabu search (TS), voltage stability margin. I.
On Market Mechanisms as a Software Technique
, 1996
"... Market mechanisms are drawing more attention in computer science as a possible approach to difficult resource allocation problems. We broadly consider the feasibility of such an approach, with the focus on optimization, at a level accessible to a general computer science audience. The nature of mark ..."
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Cited by 9 (2 self)
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Market mechanisms are drawing more attention in computer science as a possible approach to difficult resource allocation problems. We broadly consider the feasibility of such an approach, with the focus on optimization, at a level accessible to a general computer science audience. The nature of market mechanisms is discussed from both computer science and economic perspectives Classifying definitions are motivated, then applied to marketinspired software designs reported in the literature. Potential advantages and disadvantages of the market approach are identified and explained. Supported in part by a National Science Foundation Graduate Fellowship. y Supported in part by NSF grant ASC9301788. 1 Introduction The catchphrase "market mechanism" is increasingly encountered within computer science, particularly in connection with the problems of distributed resource allocation. Recently, faced with such a problem of our own, we thought to investigate whether a market approach co...