bluuebunny/crossref_metadata_2025 huggingface dataset:
A SALIENCY-BASED SEGMENTATION METHOD FOR ONLINE CURSIVE HANDWRITING
Authors: DE STEFANO CLAUDIO , GUADAGNO GIANLUCA , MARCELLI ANGELO
Published: November 2004

We propose a model for the segmentation of cursive handwriting into strokes that has been derived in analogy with those proposed in the literature for early processing tasks in primate visual system. The model allows reformulating the problem of selecting on the ink the points corresponding to perceptually relevant changes of curvature as a preattentive, purely bottom-up visual task, where the conspicuity of curvature changes is measured in terms of their saliency. The modeling of the segmentation as a saliency-driven visual task has lead to a segmentation algorithm whose architecture is biologically-plausible and that does not rely on any parameter other than those that can be directly obtained from the ink. Experimental results show that the performance is very stable and predictable, thus preventing those erratic behaviors of segmentation methods often reported in the literature. They also suggest that the proposed measure of saliency has a direct relation with the dynamics of the handwriting, so as it could be used to capture in a quantitative way some aspects of cursive handwriting intuitively related to the notion of style.
CLUSTERING AND BAYESIAN NETWORK APPROACHES FOR DISCOVERING HANDWRITING STRATEGIES OF PRIMARY SCHOOL CHILDREN
Authors: ZAAROUR I. , HEUTTE L. , LERAY PH. , LABICHE J. , ETER B. , MELLIER D.
Published: November 2004

The aim of this paper is to assess the evolution in writing performance amongst typical pupils in primary education. More precisely, we propose ways of discovering groups of pupils sharing the same writing strategies during their primary education and methods for the temporal modeling of these pupils' writing strategies. For this purpose, online acquisition of writing and drawing tests have been performed three times during a period of one year for the same pupils under the same experimental conditions. A first approach, based on clustering, is applied to highlight clusters on a set of dynamic primitives chosen by an expert in the field of child development psychology. Results are presented by means of a comparative study between features of each group and writing tests. An analysis of within and between-strategies migration of pupils over time is also conducted to highlight pupils who change (or fail to change) their writing strategies during this period of one year. A second approach is used to model the problem by means of a probabilistic graphical model, i.e. a bayesian network. Expert knowledge partially determines the bayesian network structure, in which the writing strategy is represented by a hidden variable whose cardinality is estimated by the results of the clustering approach. By considering that each writing test is represented by its own (local) strategy and that there exists a global strategy which deals with each local strategy, we propose a Global Hierarchical Model. The results of our hierarchical model structured using real data highlight, among others, two global strategies that correspond to normo-writer pupils and more advanced normo-writers. A longitudinal and temporal study of the evolution of the pupils in these strategies shows that these two strategies are consistent.
LEARNING OF THE HOPFIELD ASSOCIATIVE MEMORY BY GLOBAL MINIMIZATION
Authors: WANG TAO
Published: November 2004

In the paper, a learning algorithm for Hopfield associative memories (HAMs) is presented. According to the cost function that measures the goodness of the HAM, we determine the connection matrix using a global minimization, solved by a gradient descent rule. This optimal learning method can guarantee the storage of all training patterns with basins of attraction that are as large as possible. We also study the storage capacity of the HAM, the asymptotic stability of each training pattern and its basin of attraction. A large number of computer simulations have been conducted to show its performance.
IMAGE RETRIEVAL USING FUZZY EVALUATION OF COLOR SIMILARITY
Authors: BINAGHI ELISABETTA , GAGLIARDI ISABELLA , SCHETTINI RAIMONDO
Published: November 2004

The paper describes the design and implementation of an information retrieval system using color as the index in its color image archive. Salient aspects of this approach are the use of direct visual representation of color in querying and of fuzzy set theory to formally represent intrinsic human uncertainty in evaluating the similarity between colors (query interpretation).

The steps in which the information retrieval strategy is organized are illustrated, and an example of its application given, showing how the implemented system can be tailored to manage archives of images representing fabric samples.
A HYBRID METHOD TOWARDS THE SEGMENTATION OF RANGE IMAGES FOR 3-D OBJECT RECOGNITION
Authors: MITAL DINESH P. , TEOH EAM KHWANG , LIM ALAN W.T.
Published: November 2004

This paper presents a hybrid approach towards accomplishing the task of range image segmentation. It tends to combine region growing and one-dimensional orthogonal polynomial fitting techniques for the detection of edges in range images. Edges detected by such a method possesses good localisation property. This aids to steer the region growing process towards accomplishing accurate border partitioning. In addition, the incorporation of region growing process eliminates internal micro edges and provides for missing border reconstruction as it is able to detect weak edges. It is believed that the edge and segmentation maps produced, when conveyed to the higher level recognition process, may prove valuable not only for CAD based modeling purposes but may also aid to provide descriptive syntax to the object identification process.
ANALYSIS OF FORM IMAGES
Authors: WANG DACHENG , SRIHARI SARGUR N.
Published: November 2004

Automatic analysis of images of forms is a problem of both practical and theoretical interest; due to its importance in office automation, and due to the conceptual challenges posed for document image analysis, respectively. We describe an approach to the extraction of text, both typed and handwritten, from scanned and digitized images of filled-out forms. In decomposing a filled-out form into three basic components of boxes, line segments and the remainder (handwritten and typed characters, words, and logos), the method does not use a priori knowledge of form structure.

The input binary image is first segmented into small and large connected components. Complex boxes are decomposed into elementary regions using an approach based on key-point analysis. Handwritten and machine-printed text that touches or overlaps guide lines and boxes are separated by removing lines. Characters broken by line removal are rejoined using a character patching method. Experimental results with filled-out forms, from several different domains (insurance, banking, tax, retail and postal) are given.
MODEL-BASED ANALYSIS AND UNDERSTANDING OF CHECK FORMS
Authors: HA THIEN MINH , BUNKE HORST
Published: November 2004

Check forms are used by many people in daily life for money remittances. Surprisingly, the processing of these forms at banks and post offices is only partly automated. In this paper, we consider a particular kind of form, viz., the GIRO check forms used in Switzerland. We will describe a fully automatic system which is able to recognise the financial institution, the name and address of the receiver, and the account number on a GIRO check. The system comprises procedures for binarization, segmentation, model matching, and optical character recognition (OCR). Experiments on a sample set of 48 checks have shown promising results in terms of both computation time and recognition accuracy.
SYNTACTIC ANALYSIS OF TECHNICAL DRAWING DIMENSIONS
Authors: COLLIN SUZANNE , COLNET DOMINIQUE
Published: November 2004

We present a syntactic approach to technical drawing dimensions analysis. A specific grammar is used to describe dimensions of drawings. This grammar can be graphically designed by combining different graphic primitives. The algorithm used for analysis can start at different points of the grammar. The analysis proceeds bottom-up and top-down according to previously obtained results.
FROM 3-D SCATTERED DATA TO GEOMETRIC SIGNAL DESCRIPTION: INVARIANT STABLE RECOVERY OF STRAIGHT LINE SEGMENTS
Authors: HÉBERT PATRICK , LAURENDEAU DENIS , BERGEVIN ROBERT
Published: November 2004

Many tasks, such as pose determination, object recognition and model building rely on a geometrical description of the visible surfaces derived from scene measurements. Even though much effort has been invested in surface description, robust extraction of surface parameters from scattered and noisy 3-D measurements is still a delicate task. For a given visible surface section, the extracted parameters should not depend on the sensor position in the scene nor on a particular measurement set on this surface. In this work, we show that a viewpoint invariant and stable local surface description can be extracted on sections where measurement constraints are redundant with respect to a polynomial model. A segmentation approach is developed to identify such stable sections. The approach is based on a measurement error model which takes into account the sensor’s viewpoint. An application of the approach to the extraction of straight line sections from single scan 3-D surface profiles is presented. The extracted stable linear sections are stored in a list that includes the estimated descriptive parameters for each section and indices of reliability for each description. The descriptive parameters obtained from images of the objects is compared with pre-measured parameters.
NON-PARAMETRIC MULTISCALE CURVE SMOOTHING
Authors: ROSIN PAUL L.
Published: November 2004

Lowe8 demonstrated a method for automatically segmenting and smoothing image curves by varying degrees. It was intended to remove noise and unnecessary fine detail, aiding subsequent processing such as grouping and matching. An alternative technique is described in this paper that is based on recursively subdividing the curve into alternative sets of sections. Rather than use thresholds on the values of curvature and its derivatives to determine the segmentation and degree of smoothing our technique is driven by three qualitative measures: (1) a criterion for selecting potential breakpoints, (2) a criterion for determining the amount of smoothing for curve sections, (3) a significance measure that determines which sections form the best selection. The advantages of the technique are robustness, scale invariance, and the absence of parameters.
AN EXACT SOLUTION TO THE FITTING PROBLEM IN THE APPLICATION SPECIFIC STATE MACHINE DEVICE
Authors: PERKOWSKI MAREK A. , CHRZANOWSKA-JESKE MALGORZATA , PIERZCHALA EDMUND , COPPOLA ALAN
Published: November 2004

In this paper the fitting problem for a new Application Specific State Machine Device, CY7C361, from Cypress Semiconductor is formulated and the solution is proposed. This fitting problem consists of mapping a netlist obtained from high-level synthesis into the chip’s physical resources. In general, a mapping (fitting) problem can be formulated as one of the labeled graph isomorphism between the netlist graph and the subgraph of the resources graph. However, the specific architecture-related constraints of the CY7C361 device cause the fitting problem to be generalized as a graph isomorphism problem with some additional mapping constraints and node multiplication (placing some nodes of the netlist graph in more than one node of the physical graph). Such formulation is quite general for a class of Complex Programmable Logic Device (CPLD) fitting problems, and has not been found in the literature. We implemented an exact, constraint-based, tree searching algorithm with several kinds of backtracking.
RESULTS OF THE APPLICATION OF AN ALGORITHM FOR L2 MODEL REDUCTION
Authors: KRAJEWSKI W. , LEPSCHY A. , REDIVO-ZAGLIA M. , VIARO U.
Published: November 2004

An algorithm for L2-optimal model reduction in frequency domain is outlined. Some significant examples are illustrated to show the performance of the method and to compare the related results with those obtained using alternative techniques.
A NOVEL INVERTER-DRIVE ULTRASONIC MOTOR-ACTUATED POSITIONING SERVO MOTION SYSTEM USING A FUZZY REASONING CONTROL SCHEME
Authors: FURUYA SHIN-ICHI , OHKURA YASUYUKI , MARUHASHI TORU , NAKAOKA MUTSUO
Published: November 2004

This paper presents the operating principle of the ultrasonic motor (USM) as a new actuator and its steady-state characteristics for application-specific servo motion systems. The latest developed inverter-drive traveling wave type ultrasonic motor (TUSM) is suitable for direct-drive motion systems. We describe a positioning servo motion system using the TUSM, which operates under a feasible fuzzy-reasoning controller with velocity and positional state-variable feedback schemes. Experimental verifications are given and their results are evaluated using a one-axis servo motion drive system. It is also proved that a new compact direct-drive servo motion system using inverter-fed USM which incorporates a microprocessor-based two-input and one-output fuzzy-reasoning controller is more acceptable for a specific direct-drive application.
THE SPATIAL DILEMMAS OF EVOLUTION
Authors: NOWAK MARTIN A. , MAY ROBERT M.
Published: November 2004

Evolutionary game theory can be extended to include spatial dimensions. The individual players are placed in a two-dimensional spatial array. In each round every individual “plays the game” with its immediate neighbours. After this, each site is occupied by its original owner or by one of the neighbours, depending on who scored the highest payoff. These rules specify a deterministic cellular automaton.

We find that spatial effects can change the outcome of frequency dependent selection. Strategies may coexist that would not coexist in homogeneous populations. Spatial games have interesting mathematical properties. There are static or chaotically changing patterns. For symmetrical starting conditions we find “dynamical fractals” and “evolutionary kaleidoscopes.” There is a new world to be explored.
TORI AND CHAOS IN A NONLINEAR DYNAMO MODEL FOR SOLAR ACTIVITY
Authors: FEUDEL ULRIKE , JANSEN WOLFGANG , KURTHS JÜRGEN
Published: November 2004

A nonlinear dynamo model for solar activity which includes the feedback of the helicity upon the mean magnetic field has been investigated. The qualitative behavior of a seven-dimensional system of ordinary differential equations obtained by truncation of that model has been studied numerically. It has been compared with results from a sixth order system derived from the seventh order system by a special polar coordinate transformation. Depending on characteristic parameters, the seven-dimensional model exhibits periodic, quasiperiodic (on T2 and T3) and chaotic behavior where a route to chaos via the transition T2⇒T3⇒T2⇒ chaos has been found to be typical. In contrast to that, no chaotic state occurs in the reduced system due to a nonregularity of the coordinate transformation.
ON BEHAVIORS OF TWO-DIMENSIONAL ENDOMORPHISMS: ROLE OF THE CRITICAL CURVES
Authors: MIRA CHRISTIAN , NARAYANINSAMY TONY
Published: November 2004

Critical curves are the natural two-dimensional extension of the notion of critical points in one-dimensional endomorphisms. They play a fundamental role in determining the dynamical properties and their bifurcations. This letter demonstrates such a role for two new behaviors.
“LORENZ ATTRACTOR” FROM DIFFERENTIAL EQUATIONS WITH PIECEWISE-LINEAR TERMS
Authors: BAGHIOUS E.H. , JARRY P.
Published: November 2004

In this paper we present a simple piecewise-linear circuit which exhibits a chaotic attractor similar to that observed from the Lorenz equation. Whereas the nonlinearities in the Lorenz equation consists of two product terms between two state variables, the nonlinearities in our circuit consists of two piecewise-linear terms.
CONTROL OF THE TRANSITION TO CHAOS IN NEURAL NETWORKS WITH RANDOM CONNECTIVITY
Authors: DOYON B. , CESSAC B. , QUOY M. , SAMUELIDES M.
Published: November 2004

The occurrence of chaos in recurrent neural networks is supposed to depend on the architecture and on the synaptic coupling strength. It is studied here for a randomly diluted architecture. We produce a bifurcation parameter independent of the connectivity that allows a sustained activity and the occurrence of chaos when reaching a critical value. Even for weak connectivity and small size, we find numerical results in accordance with the theoretical ones previously established for fully connected infinite sized networks. Moreover the route towards chaos is numerically checked to be a quasiperiodic one, whatever the type of the first bifurcation is. In the discussion, we connect these results to some recent theoretical results about highly diluted networks. Hints are provided for further investigations to elicit the role of chaotic dynamics in the cognitive processes of the brain.
SPREAD SPECTRUM COMMUNICATION THROUGH MODULATION OF CHAOS
Authors: HALLE K. SEAN , WU CHAI WAH , ITOH MAKOTO , CHUA LEON O.
Published: November 2004

In this letter we demonstrate experimentally how Chua’s circuits can be used to implement a secure communication system. This system is compared to another system proposed earlier. This system has the advantage of transmitting a spread spectrum signal and is also more secure in the sense that better parameter matching is required in order to recover the signal. Furthermore, there is less of a problem with loss of synchronization.
SUMMARY OF THE SECOND WORKSHOP ON MEASURES OF COMPLEXITY AND CHAOS
Authors: GILMORE R.
Published: November 2004

We summarize the presentations made at the Second Workshop on Measures of Complexity and Chaos, held on the campus of Bryn Mawr College during August 13–15, 1992.
USING COARSE-GRAINED MEASURES TO CHARACTERIZE ELECTROMYOGRAPHIC SIGNALS
Authors: RAPP P.E. , GOLDBERG G. , ALBANO A.M. , JANICKI M.B. , MURPHY D. , NIEMEYER E. , JIMÉNEZ-MONTAÑO M.A.
Published: November 2004

Human electromyograms were obtained from normal muscle and from spontaneously fibrillating, denervated muscle, and the time intervals between spikes in electrical activity were measured. The entropy and measures related to the entropy were used to examine these data. We have achieved a statistically significant discrimination between normal and denervated muscle (p<0.0002) using a measure (the second moment of the distribution) that requires less than 200 consecutive interspike intervals in a calculation that requires less than 2 milliseconds. This suggests that real time monitoring may be feasible. The range of values obtained for the second moment for the two conditions (normal versus denervated) did not overlap. Complete separation was achieved. A measure analogous to the two-dimensional product of inertia which is sensitive to dynamical structure in the data was also calculated. Again, complete separation of values obtained in the two cases was observed. Further research is required to determine if these measures can aid in the differential diagnosis of neuromuscular disorders and in the longitudinal assessment of the efficacy of treatment.

In this review we also establish the relationships between conventional statistical measures and the limiting values of coarse grained measures obtained as the number of elements in the partition approaches infinity.
LOCAL OR DYNAMICAL DIMENSIONS OF NONLINEAR SYSTEMS INFERRED FROM OBSERVATIONS
Authors: ABARBANEL HENRY D.I. , SUSHCHIK MIKHAIL M.
Published: November 2004

In time delay reconstruction of the phase space of a system from observed scalar data, one requires a time lag and an integer embedding dimension. The minimum embedding dimension, dE, may be larger than the actual local dimension of the underlying dynamics, dL. The embedding theorem only guarantees that the attractor of the system is unfolded in the integer dE greater than 2dA with dA being the attractor dimension. We present two methods for determining the dimension, dL≤dE, of the underlying dynamics. The first relies on the local Lyapunov exponents of the dynamics, and the second seeks an optimum dimension for prediction of the time series for steps forward and then backward in time. We demonstrate these methods on several examples. Model building of the dynamics should take place in the dL-dimensional space.
METRIC UNIVERSALITY OF ORDER IN ONE-DIMENSIONAL DYNAMICS
Authors: FRAME MICHAEL , PEAK DAVID
Published: November 2004

The orbit of the critical point of a nonlinear dynamical system defines a family of functions in the parameter space of the system. For unimodal maps a renormalization makes these functions indistinguishable over a wide range of parameter values. The universal representation of these functions leads directly to a number of interesting results: (1) the positions in the parameter space of the windows of order; (2) the sizes of the windows of order; (3) measures of distortion in the window structure; and (4) various generalized Feigenbaum numbers. We explicitly discuss the examples of the quadratic and sine maps.
A NEW APPROACH TO TESTING FOR CHAOS, WITH APPLICATIONS IN FINANCE AND ECONOMICS
Authors: GILMORE CLAIRE G.
Published: November 2004

Whether certain financial and economic time series exhibit chaotic behavior is an issue currently in dispute. Empirical research on chaotic behavior in such data has been hampered by lack of an adequate test. Metric methods do not produce reliable results when applied to small, noisy data sets. Thus, reported results have been inconclusive. Here we apply a new, topological approach to analyzing for chaos, recently developed in the physics literature, to a number of financial and economic series previously subjected to metric tests. The results of the topological test are compared with those reported in the literature using metric methods.
EVALUATING DETERMINISTIC STRUCTURE IN MAPS DEDUCED FROM DISCRETE-TIME MEASUREMENTS
Authors: KAPLAN DANIEL T.
Published: November 2004

A method is presented for quantifying the determinism of dynamics reconstructed from discrete-time measurements. To illustrate the use of the method, it is applied to three systems: a cosine map, an Anosov diffeomorphism, and an experimental system of coupled nonlinear oscillators.
EXPERIMENTAL APPROACH TO A COMPLEX ACOUSTIC SYSTEM
Authors: LAUTERBORN W. , SCHMITZ E. , JUDT A.
Published: November 2004

A liquid is subjected to sound of high intensity to generate a cloud of cavities or bubbles. The correlation between the sound output from the bubble cloud, which follows a subharmonic route to chaos with a low-dimensional strange attractor, and its spatial dynamics is investigated. Several approaches are used. In a light transmission experiment the light modulation resulting from the spatial dynamics gives an integrated measure similar to the acoustic output from a hydrophone. High speed photographic cinematography and, in particular, methods of high speed holographic cinematography are used and developed to capture the spatial dynamics of the three-dimensional bubble pattern, a filamentary structure resembling Lichtenberg figures. The series of three-dimensional images obtained via holography is digitized and analyzed via a transputer-based digital image processing system. First results show strong correlations among the behavior of individual bubbles and indicate a highly cooperative system. The method of high speed holographic cinematography developed together with a digital holographic image processing system will also be of use for the investigation of other complex space-time systems, for example, the Rayleigh-Bénard and Taylor-Couette systems, and is scheduled for fully three-dimensional turbulence studies.
PARSIMONIOUS DYNAMICAL RECONSTRUCTION
Authors: MEES ALISTAIR
Published: November 2004

Many nonlinear deterministic models of time series have large numbers of parameters and tend to overfit in the presence of noise. This paper shows how to generate radial basis function models with small numbers of parameters for a given quality of fit. It also addresses questions of how to select subsets from candidate sets of centers for radial basis function models, and what kinds of basis functions to use, as well as how large a model is appropriate.
CHAOS VERSUS NOISE IN EXPERIMENTAL DATA
Authors: MITSCHKE F. , DÄMMIG M.
Published: November 2004

Problems of the distinction between stochastic and deterministically chaotic data are discussed. Conventional attempts such as calculation of dimensions, entropies, or Lyapunov exponents are shown to be prone to errors, or outright useless. We test the recently proposed method of surrogate data with time series from numerical and from real world experiments. This technique turns out to be a useful tool for the distinction, far superior to previous approaches.
COMMON DYNAMICAL FEATURES OF PERIODICALLY DRIVEN STRICTLY DISSIPATIVE OSCILLATORS
Authors: PARLITZ ULRICH
Published: November 2004

Periodically driven strictly dissipative nonlinear oscillators in general possess a recurring bifurcation structure in parameter space. It consists of slightly modified versions of a basic pattern of bifurcation curves that was found to be essentially the same for many different oscillators. The periodic orbits involved in these bifurcation scenarios also possess common topological properties characterized in terms of their torsion numbers and the way they are connected when parameters are varied. In this paper, this typical bifurcation structure of periodically driven strictly dissipative oscillators will be presented and discussed in terms of examples from Duffing’s equation. Furthermore a family of two-dimensional maps is given that models (strictly) dissipative oscillators and shows essential features of the bifurcation pattern found.
HOW MANY DELAY COORDINATES DO YOU NEED?
Authors: SAUER TIM , YORKE JAMES A.
Published: November 2004

Theorems on the use of delay coordinates for analyzing experimental data are discussed. To reconstruct a one-to-one correspondence with the state-space attractor, m delay coordinates are sufficient, where m>2D0 (here D0 denotes the box-counting dimension). For calculating the correlation dimension D2, m>D2 delays are sufficient. These results remain true under finite impulse response (FIR) filters.
STATISTICAL ERROR IN A CHORD ESTIMATOR OF CORRELATION DIMENSION: THE “RULE OF FIVE”
Authors: THEILER JAMES , LOOKMAN TURAB
Published: November 2004

The statistical precision of a chord method for estimating dimension from a correlation integral is derived. The optimal chord length is determined, and a comparison is made with other estimators. The simple chord estimator is only 25% less precise than the optimal estimator which uses the full resolution and full range of the correlation integral. The analytic calculations are based on the hypothesis that all pairwise distances between the points in the embedding space are statistically independent. The adequacy of this approximation is assessed numerically, and a surprising result is observed in which dimension estimators can be anomalously precise for sets with reasonably uniform (nonfractal) distributions.
DISCRETE DYNAMICAL MODELS SHOWING PATTERN FORMATION IN SUBAQUEOUS BEDFORMS
Authors: TUFILLARO NICHOLAS B.
Published: November 2004

A new class of “toy models” for subaqueous bedform formation are proposed and examined. These models all show a similar mechanism of wavelength selection via bedform unification, and they may have applications to bedform stratigraphy. The models are also useful for exploring general issues of pattern formation and complexity in stochastically driven far-from-equilibrium systems.
THE MARGINAL STABILITY OF AUTONOMOUS DIFFERENTIAL EQUATIONS
Authors: GREENBAUN N.N.
Published: November 2004

Solutions in the vicinity of a steady state solution to a system of autonomous nonlinear differential equations are of interest to modelers. The usual method for determining marginal stability of the steady state is the Routh-Hurwitz criterion. The method offered here is less complicated and more efficient when the number of state variables exceeds three.
THE BOGDANOV MAP: BIFURCATIONS, MODE LOCKING, AND CHAOS IN A DISSIPATIVE SYSTEM
Authors: ARROWSMITH DAVID K. , CARTWRIGHT JULYAN H. E. , LANSBURY ALEXIS N. , PLACE COLIN M.
Published: November 2004

We investigate the bifurcations and basins of attraction in the Bogdanov map, a planar quadratic map which is conjugate to the Hénon area-preserving map in its conservative limit. It undergoes a Hopf bifurcation as dissipation is added, and exhibits the panoply of mode locking, Arnold tongues, and chaos as an invariant circle grows out, finally to be destroyed in the homo-clinic tangency of the manifolds of a remote saddle point. The Bogdanov map is the Euler map of a two-dimensional system of ordinary differential equations first considered by Bogdanov and Arnold in their study of the versal unfolding of the double-zero-eigenvalue singularity, and equivalently of a vector field invariant under rotation of the plane by an angle 2π. It is a useful system in which to observe the effect of dissipative perturbations on Hamiltonian structure. In addition, we argue that the Bogdanov map provides a good approximation to the dynamics of the Poincare maps of periodically forced oscillators.
CHAOTIC BEHAVIOR OF HIGHER DIMENSIONAL TRANSFORMATIONS DEFINED ON COUNTABLE PARTITIONS
Authors: BOYARSKY A. , LOU Y. S.
Published: November 2004

Jablonski maps are higher dimensional maps defined on rectangular partitions with each component a function of only one variable. It is well known that expanding Jablonski maps have absolutely continuous invariant measures. In this note we consider Jablonski maps defined on countable partitions. Such maps occur, for example, in multivariable number theoretic problems. The main result establishes the existence of an absolutely continuous invariant measure for Jablonski maps on a countable partition with the additional condition that the images of all the partition elements form a finite collection. An example is given.
NORMAL FORMS AND LORENZ ATTRACTORS
Authors: SHIL'NIKOV A. L. , SHIL'NIKOV L. P. , TURAEV D. V.
Published: November 2004

Normal forms for eleven cases of bifurcations of codimension-3 are considered, basically, in systems with a symmetry, which can be reduced to one of the two three-dimensional systems. The first system is the well-known Lorenz model in a special notation, the second is the Shimizu-Morioka model. In contrast with two-dimensional normal forms which admit, in principle, a complete theoretical study, in three-dimensional systems such analysis is practically impossible, except for particular parameter values when a system is close to an integrable system. Therefore, the main method of the investigation is qualitatively-numerical. In that sense, a description of principal bifurcations which lead to the appearance of the Lorenz attractor is given for the models above, and the boundaries of the regions of the existence of this attractor are selected.

We pay special attention to bifurcation points corresponding to a formation of a homoclinic figure-8 of a saddle with zero saddle value and that of a homoclinic figure-8 with zero separatrix value. In L. P. Shil'nikov [1981], it was established that these points belong to the boundary of the existence of the Lorenz attractor. In the present paper, the bifurcation diagrams near such points for the symmetric case are given and a new criterion of existence of the nonorientable Lorenz is also suggested.
BIFURCATION ANALYSIS OF DOUBLE TAKENS–BOGDANOV POINTS OF NONLINEAR EQUATIONS WITH A Z2-SYMMETRY
Authors: SPENCE ALASTAIR , WEI WU , ROOSE DIRK , DE DIER BART
Published: November 2004

We consider the nonlinear equation f (x, Λ) = 0, f: X × ℝ3 → X, where X is a Banach space and f satisfies a Z2-symmetry relation. We are interested in a singular point (x0, Λ0) called a double Takens–Bogdanov point, where fx has a zero eigenvalue of geometric multiplicity 2 and algebraic multiplicity 3. We show that only three parameters are needed to recognise and compute this singular point when the Z2-symmetry is present. Paths of the following three kinds of singular points bifurcating at this double Takens–Bogdanov point are studied: double s-breaking fold points (where fx has a zero eigenvalue of algebraic and geometric multiplicity 2), Takens–Bogdanov points (a zero eigenvalue of geometric multiplicity 1 and algebraic multiplicity 2) and s-breaking G points (a simple zero eigenvalue and a pair of simple purely imaginary eigenvalues). The theory is developed in such a way as to produce nondegeneracy conditions and tests which may be utilised in numerical calculations. Numerical results are presented for the one-dimensional Brusselator model, described by a system of four reaction–diffusion equations.
LOW-DIMENSIONAL BEHAVIOR OF NONLINEAR TEARING MODE DYNAMICS IN A ROTATING PLASMA
Authors: PERSSON M. , LAING C. R.
Published: November 2004

Simulations of resistive magnetohydrodynamics in a rotating plasma are analyzed by calculating the correlation dimensions and the local intrinsic dimensions. A rotating plasma with a nonlinear oscillatory state is found to be associated with a low-dimensional attractor. The solutions are also checked for sensitivity to initial conditions, characterized by the sign of the largest Lyapunov exponent.
THE INDEX ON THE MANDELBROT SET
Authors: FUJIMOTO YOSHIHISA
Published: November 2004

It is known that the index on the Mandelbrot set introduces a Fibonacci partition. In this paper we will give an interpretation of this property.
TRANSITION WAVES THAT LEAVE BEHIND REGULAR OR IRREGULAR SPATIOTEMPORAL OSCILLATIONS IN A SYSTEM OF THREE REACTION–DIFFUSION EQUATIONS
Authors: SHERRATT JONATHAN A.
Published: November 2004

Transition waves are widespread in the biological and chemical sciences, and have often been successfully modelled using reaction–diffusion systems. I consider a particular system of three reaction–diffusion equations, and I show that transition waves can destabilise as the kinetic ordinary differential equations pass through a Hopf bifurcation, giving rise to either regular or irregular spatiotemporal oscillations behind the advancing transition wave front. In the case of regular oscillations, I show that these are periodic plane waves that are induced by the way in which the transition wave front approaches its terminal steady state. Further, I show that irregular oscillations arise when these periodic plane waves are unstable as reaction–diffusion solutions. The resulting behavior is not related to any chaos in the kinetic ordinary differential equations.
SPATIAL DISORDER AND WAVE FRONTS IN A CHAIN OF COUPLED CHUA'S CIRCUITS
Authors: NEKORKIN V. I. , CHUA L. O.
Published: November 2004

Dynamics of a chain of coupled Chua's circuits is investigated. Existence of spatial disorder is revealed. Dynamics of wave fronts in the limiting case of a continuous medium is studied.
PREDICTOR-CORRECTOR TECHNIQUES FOR DETECTING HOPF BIFURCATION POINTS
Authors: NEUBERT R.
Published: November 2004

A new method for stability analysis during continuation is proposed. The method uses shifted inverse iteration to compute a relevant eigenvalue, determining stability. Some additional work has to be done to verify the above solution. Numerical experiments are performed using models of the tubular reactor and the Brusselator.
FROM CHAOS TO ORDER — PERSPECTIVES AND METHODOLOGIES IN CONTROLLING CHAOTIC NONLINEAR DYNAMICAL SYSTEMS
Authors: CHEN GUANRONG , DONG XIAONING
Published: November 2004

Controlling (or ordering) chaos is a new concept, which has recently drawn much attention from the communities of engineering, physics, chemistry, biomedical sciences and mathematics. This paper offers an overview of the different interpretations and approaches in the investigation of controlling chaos for various nonlinear dynamical systems. Relevant historical background is provided, several successful techniques are described and analyzed with necessary verifications, and some realistic yet instructive examples are included. The paper also aims at promoting more efforts to be devoted to this challenging and promising new direction of research, as well as its potential applications in nonlinear systems science and engineering.
ON THE PRESENCE OF NORMALLY ATTRACTING MANIFOLDS CONTAINING PERIODIC OR QUASIPERIODIC ORBITS IN COUPLED MAP LATTICES
Authors: GIBERTI CLAUDIO , VERNIA CECILIA
Published: November 2004

The significant presence of normally attracting invariant manifolds, formed by closed curves or two-tori, is investigated in two-dimensional lattices of coupled chaotic maps. In the case of a manifold formed by closed curves, it contains symmetrically placed periodic orbits, with the property of a very weak hyperbolicity along the manifold itself. The resulting dynamics is an extremely slow relaxation to periodic behavior. Analogously, a manifold consisting of two-tori includes very weakly hyperbolic periodic (or quasiperiodic) orbits, which in this case also implies quite a long time before any solution approaches periodicity or quasiperiodicity.

The normally attracting manifolds and the contained weak attractors can undergo several global bifurcations. Some of them, including saddle-node bifurcation, period-doubling and Hopf bifurcation, are illustrated.

Almost all the asymptotic solutions that we discuss have flat rows or flat columns, which means that they can occur also in one-dimensional lattices.
BIFURCATION STRUCTURE OF THE DRIVEN VAN DER POL OSCILLATOR
Authors: METTIN R. , PARLITZ U. , LAUTERBORN W.
Published: November 2004

The bifurcation set in the three-dimensional parameter space of the periodically driven van der Pol oscillator has been investigated by continuation of local bifurcation curves. The two regions in which the driving frequency ω is greater or less than the limit cycle frequency ω0 of the nondriven oscillator are considered separately. For the case ω > ω0, the subharmonic region, the extent and location of the largest Arnol'd tongues are shown, as well as the period-doubling cascades and chaotic attractors that appear within most of them. Special attention is paid to the pattern of the bifurcation curves in the transitional region between low and large dampings that is difficult to approach analytically. In the case ω < ω0, the ultraharmonic region, a recurrent pattern of the bifurcation curves is found for small values of the damping d. At medium damping the structure of the bifurcation curves becomes involved. Period-doubling sequences and chaotic attractors occur.
CYCLES OF CHAOTIC INTERVALS IN A TIME-DELAYED CHUA'S CIRCUIT
Authors: MAISTRENKO Yu. L. , MAISTRENKO V. L. , CHUA L. O.
Published: November 2004

We study the bifurcations of attractors of a one-dimensional 2-segment piecewise-linear map. We prove that the parameter regions of existence of stable point cycles γ are separated by regions of existence of stable interval cycles Γ containing chaotic everywhere dense trajectories. Moreover, we show that the period-doubling phenomenon for cycles of chaotic intervals is characterized by two universal constants δ and α, whose values are calculated from explicit formulas.
PALEOCLIMATIC ATTRACTORS: NEW DATA, FURTHER ANALYSIS
Authors: ELGAR STEVE , KADTKE JAMES
Published: November 2004

Analysis of a high resolution record of climate change spanning the past 2.6 million years suggests that the dynamics of the climate is not high dimensional, similar to previous results using much shorter records [Nicolis & Nicolis 1984, Vautard & Ghil 1989]. The correlation dimension is significantly less than the dimension of a linear, Gaussian process with the same power spectrum (i.e., phase-randomized surrogate data) as the climate record. The climatic correlation dimension is similar to the dimension of a model of the solar forcing of climate, suggesting the possibility of a linear climate-system response to orbital forcing, consistent with frequency-domain analysis results [Hays et al., 1976, Imbrie & Imbrie, 1980]. Consequently, inferring an inherently nonlinear (possibly chaotic) climate system without considering the nonlinear (possibly chaotic) insolation forcing dynamics could be misleading.
A SIMPLE WAY TO SYNCHRONIZE CHAOTIC SYSTEMS WITH APPLICATIONS TO SECURE COMMUNICATION SYSTEMS
Authors: WU CHAI WAH , CHUA LEON O.
Published: November 2004

In this paper, we provide a scheme for synthesizing synchronized circuits and systems. Synchronization of the drive and response system is proved trivially without the need for computing numerically the conditional Lyapunov exponents. We give a definition of the driving and response system having the same functional form, which is more general than the concept of homogeneous driving by Pecora & Carroll [1991]. Finally, we show how synchronization coupled with chaos can be used to implement secure communication systems. This is illustrated with examples of secure communication systems which are inherently error-free in contrast to the signal-masking schemes proposed in Cuomo & Oppenheim [1993a,b] and Kocarev et al. [1992].
PROGRAMMABLE REVERSE ENGINEERING
Authors: TILLEY SCOTT R. , WONG KENNY , STOREY MARGARET-ANNE D. , MÜLLER HAUSI A.
Published: November 2004

Program understanding can be enhanced using reverse engineering technologies. The understanding process is heavily dependent on both individuals and their specific cognitive abilities, and on the set of facilities provided by the program understanding environment. Unfortunately, most reverse engineering tools provide a fixed palette of extraction, selection, and organization techniques. This paper describes a programmable approach to reverse engineering. The approach uses a scripting language that enables users to write their own routines for common reverse engineering activities, such as graph layout, metrics, and subsystem decomposition, thereby extending the capabilities of the reverse engineering toolset to better suit their needs. A programmable environment supported by this approach subsumes existing reverse engineering systems by being able to simulate facets of each one.
THE EXTENSIBLE DEPENDENCY ANALYSIS TOOL SET: A KNOWLEDGE BASE FOR UNDERSTANDING INDUSTRIAL SOFTWARE
Authors: WILDE NORMAN , CHAPMAN ALLEN , RICHARDSON RAYMOND
Published: November 2004

Industrial software systems are generally both large and complex. They tend to contain multiple languages and diverse kinds of structure that maintainers need to understand to do their jobs effectively. The Extensible Dependency Analysis Tool Set (EDATS) has been designed to provide support for understanding these kinds of systems. The EDATS concept emerged from discussions with industrial affiliates of the Software Engineering Research Center. It is built around a very flexible underlying structure in which software is represented as a generalized dependency graph; queries “by example” request chains of links from that graph. Information from diverse sources can be incorporated and the tool set can be easily extended to handle special relationships found in a particular system. A small case study is presented to illustrate the kinds of questions that maintainers tend to ask in understanding an unfamiliar system and to show how EDATS can help in answering such questions.
Maximal Balls of Linearly Separable Sets
Authors: SRINIVASAN VIJAY , NACKMAN LEE R.
Published: November 2004

Maximal balls (and the associated maximal spheres) between sets arise naturally in several areas of computational geometry such as the Voronoi diagram and the symmetric axis transform. We give necessary and sufficient conditions for the existence and uniqueness of maximal spheres to pass through specified points in a linear separator between sets in Ed. These results are applicable in certain problems of simplicial decomposition of domains.
A CONVEX HULL ALGORITHM FOR POINTS WITH APPROXIMATELY KNOWN POSITIONS
Authors: FRANCIOSA PAOLO GIULIO , GAIBISSO CARLO , GAMBOSI GIORGIO , TALAMO MAURIZIO
Published: November 2004

We consider the problem of deriving good approximations of the convex hull of a set of points in the plane in the realistic case that only arbitrary finite approximations of the real valued coordinates can be known. In particular, the algorithm we introduce derives sequences of improved certified approximations converging to the exact solution, at the same time allowing the insertion of new points to the problem instance.

The complexity analysis of the algorithm is performed by referring to a suitable computation model, based on a RAM with logarithmic costs, and the derived space and time bounds are shown to be competitive with respect to current off-line algorithms.
N-DIMENSIONAL GENERALIZED COMBINATORIAL MAPS AND CELLULAR QUASI-MANIFOLDS
Authors: LIENHARDT PASCAL
Published: November 2004

The scope of this work is Geometric Modeling. We study the representation and the construction of subdivisions of quasi-manifolds, using a topology-based approach. Quasi-manifolds are here defined as a subset of pseudo-manifolds, which are well-known objects in Algebraic Topology.

N-dimensional generalized maps (resp. n-dimensional maps) are combinatorial models defined for representing the topology of subdivisions of orientable or non-orientable quasi-manifolds with or without boundaries (resp. orientable quasi-manifolds without boundaries).

In this paper, we define the models, main related notions and properties as cells, boundaries, duality, orientability, Euler characteristic. Basic operations are proposed for handling the models.

We also show the correspondence between the combinatorial models and combinatorial cellular quasi-manifolds, here defined as combinatorial simplicial quasi-manifolds to which a structure into cells is added. This correspondence establishes that the models are rigorous and unambiguous ones.

Moreover, the definitions of the models and the related notions and operations are quite simple, and they can be easily implemented and used in geometric modellers.
COMBINATORIAL PROPERTIES AND HOMOMORPHISMS OF SEMIGROUPS
Authors: KELAREV A.V.
Published: November 2004

A complete description of ultrarepetitive semigroups is given. As an application of this result all semigroups S are described such that the class of permutational semigroups is S-closed, i.e., closed under taking preimages of certain homomorphisms onto S.
RANK AND PRIMITIVITY OF ELEMENTS OF FREE COLOUR LIE (p-)SUPERALGEBRAS
Authors: MIKHALEV ALEXANDER A. , ZOLOTYKH ANDREJ A.
Published: November 2004

Using Fox differential calculus we study characteristics of orbits of elements of free colour Lie (p-)superalgebras under action of the automorphism groups of these algebras. In particular, an effective criterion for an element to be primitive and an algorithm for finding the rank of an element are obtained.
ON REPRESENTATION SYSTEMS
Authors: CARPI ARTURO
Published: November 2004

We introduce the notion of a representation system: it can be viewed as a generalization of a numeration system in an integer base by means of which certain words on a finite alphabet can be represented. We show that under suitable hypotheses, concatenation of words is represented by a right-synchronized rational relation. We study languages which are represented by rational sets (this is the case, e. g., of the languages of binary overlap-free words, of partially abelian square-free words on three letters, and of a large class of PD0L languages). Several results on these languages are obtained, concerning density, prolongability, pattern-freeness.
RECENT STUDIES OF DIYNE MONOMERS CONTAINING PYRIDINE AS AN ELECTRON WITHDRAWING GROUP
Authors: MILBURN G.H.W. , WRIGHT J. , SHAND A.J. , WERNINCK A.R.
Published: November 2004

Some recent developments in diacetylene synthesis are discussed and some interesting physical properties are reported. Examples are given of unsymmetrical diacetylenes containing a pyridine ring bonded directly to one end of the diyne unit and an aryl system containing a flexible alkoxy chain joined to the opposite end. Mesophase and nonlinear optical properties are examined.