bluuebunny/crossref_metadata_2025 huggingface dataset:
THE ATOMIC AND ELECTRONIC STRUCTURE OF THE SINGLE STEPS ON THE Si(001) SURFACE
Authors: UCHIYAMA TOSHIHIRO
Published: November 2004

Recent development of the scanning tunneling microscope (STM), which is one of the most powerful tools to study solid surface, has given the atomic-resolution images of the terraces and steps on the Si(001) vicinal surface. Around the S A step, the spectrum of the scanning tunneling spectroscopy (STS) exhibits a few characteristic peaks. This observation suggests that there exists an unique state at the step edge. In this review, I describe the atomic and electronic structure of the single steps on the Si(001) surface.
QUANTUM STOCHASTIC EQUATIONS FOR A NON-LINEAR DAMPED OSCILLATOR
Authors: SAITO T. , ARIMITSU T.
Published: November 2004

A unified framework of stochastic differential equations for quantum systems, formulated within Non-Equilibrium Thermo Field Dynamics (NETFD), is applied to a model of non-linear damped oscillator. The quantum stochastic Liouville equation and the quantum Langevin equations (both of Ito and Stratonovich type), which are consistent with the corresponding master equation, are written down explicitly in the case of a non-conventional treatment. This solves Kubo's third problem: how one can obtain the correlations of random force operators for the Langevin equation compatible with the master equation derived by the non-conventional treatment of the damping theory.
SURFACE MAGNETISM OF GADOLINIUM
Authors: MULHOLLAN GREGORY A.
Published: November 2004

The surface magnetism of Gd exhibits a variety of unusual phenomena. This is not to say the book has been closed on the bulk properties. Indeed, characterization of the single crystal critical behavior is an ongoing field. In this light, it is not surprising that studies of the surface magnetic properties of Gd have lagged those of the transition metal magnets. The delay has primarily been due to the difficulty in obtaining a sufficiently pure sample. We report on the methods available for creating an atomically clean surface, the newly measured surface structure, the hows and whys of the surface enhanced magnetic order displayed by Gd and finally lay to rest the possibility of antiparallel coupling of the surface layer to the bulk.
STUDY ON THE MOST PROBABLE DISTRIBUTION FOR LAUGHLIN WAVE FUNCTIONS
Authors: QIN SHAOJIN , SU ZHAOBIN , WANG BINGSHEN
Published: November 2004

We show that, up to a global phase freedom, the most probable distribution of electrons given by the maxima of modulus square of Laughlin wave function (LWF), which is known to be a wave function for an incompressible liquid state of fractional Hall effect, has a triangular lattice structure. We introduce the Gaussian approximation for the modulus square of LWF. We find that the radial distribution function calculated from the Gaussian approximation has a form close to that of LWF at ν = 1, 1/3 and close to a crystal-like behavior when ν becomes smaller. We interprete the underlying physics to be that in the incompressible liquid regime, the "hidden" triangular lattice is smeared away by the quantum phase fluctuation, and as a precursor for liquid-crystal transition when the filling ν decreases towards the crystallization regime, it might manifest itself to be a sort of correlated short-range ordered density fluctuation.
MEAN-FIELD RENORMALIZATION GROUP: BIBLIOGRAPHY AND NEW APPLICATIONS USING LARGE CLUSTERS
Authors: CROES K. , INDEKEU J. O.
Published: November 2004

Renormalization group recursions based on mean-field approximations [J. O. Indekeu, A. Maritan, and A. L. Stella, J. Phys.A15, L291 (1982)], commonly referred to as mean-field renormalization group methods (MFRG), have proven to be efficient and easily applicable for computing non-classical critical properties of lattice models. We give a fairly complete bibliography of applications to date, and extend previous test calculations of bulk, surface, and corner critical exponents in the two-dimensional Ising model to larger cluster sizes on triangular, square (including crossing bonds), and honeycomb lattices. Without much effort the exact value of the critical exponent ratioyH/yT is reproduced systematically with a precision of 2%. This ratio turns out to be the most accurate probe of non-classical critical behaviour that is available in the MFRG method.
THE PARAMAGNETIC SUSCEPTIBILITY AND CROSSOVER TRANSITION IN U=∞ HUBBARD MODEL
Authors: GORYACHEV E.G. , KUZNETSOV D.V.
Published: November 2004

Paramagnetic susceptibility χ(0, 0)=dR(H)/dH in (H→0, U=∞) Hubbard model has been calculated in the second order of a kinematic field. The final result changes cardinally the conclusion about paramagnetic’s instability which was derived from the theory of the first order in kinematic field at T=0 and ρ=1/2W.1 The obtained expression for χ(0, 0) possesses Pauli limit for n→0 with factor 2, has strong correlated enhancement (≈5 times as large) in the region of intermediate filling of the band (n≈0.5), and determines the paramagnetic-ferromagnetic transition as a crossover transition (i.e. without finite or infinite discontinuity).
A SIMPLE PRESSURIZED SPARKGAP FOR PLASMA FOCUS OPERATION
Authors: ZAKAULLAH M. , KAUSAR SAMIA , AHMED IMTIAZ , MURTAZA G. , BEG M.M.
Published: November 2004

A simple, low-inductance, cost-effective pressurized sparkgap is developed for a low-energy plasma focus operation energised by a single 32 µF, 15 kV (3.6 kJ) capacitor. This sparkgap is capable of handling discharge current up to 200 kA with a rise time of less than one µsec. The system works reliably and is reproducible for capacitor charging of 10–13 kV.
DYNAMIC SCALING THEORY FOR SOUND PROPAGATION IN RANDOMLY-STIRRED FLUIDS
Authors: BHATTACHARJEE JAYANTA K.
Published: November 2004

We show that dynamic scaling leads to scale-dependent sound velocity and attenuation in a randomly stirred weakly compressible fluid. The attenuation and dispersion are obtained.
THE REFRACTIVE INDEX OF HYDROGEN AS A FUNCTION OF PRESSURE
Authors: RUOFF ARTHUR L. , GHANDEHARI KOUROS
Published: November 2004

It is shown that the refractive index of hydrogen is given by n H 2 = 1 + 3.046 ρ + 2.6 ρ2 where ρ has units of mol/cm3. Here ρ at a given pressure, P, can be obtained from the equation of state, ρ(P). This relation is combined with that for the refractive index of loaded diamond anvils to obtain n H 2/n D vs P. This is found to be in good agreement with the ratio n H 2/nD measured directly at different pressures by Fabry-Perot interferometry. The density variation of the molar refraction is computed.
AHARONOV-BOHM OSCILLATIONS IN A SPIN-CHARGE-SEPARATED SYSTEM
Authors: KRIVE I. , WENDIN G.
Published: November 2004

The Little-Parks-like experiment for the superconducting phase of a spin-charge-separated system is analyzed. It is shown that the distinctive feature of spin-charge separation is the specific abrupt dependence of amplitude of critical temperature oscillations on the hole concentration.
DYNAMICAL CORRELATION THEORY FOR AN ESCAPE PROCESS
Authors: AO PING
Published: November 2004

A dynamical theory which incorporates the electron-electron correlations and the effects of external magnetic fields for an electron escaping from a helium surface are presented. The degrees of freedom in the calculation of the escape rate is reduced from 3N to 3 as compared with other approach. Explicit expressions for the escape rate in various situations are obtained. In particular, in the weak parallel magnetic field limit, the tunneling rate has an exponential dependence quadratic with magnetic field strength and an unusual exponential increase linear with temperature.
CONDENSED MATTER EFFECTS ON FUSION NEUTRINO PRODUCTION RATES
Authors: KIM Y.E. , YOON J.-H. , RABINOWITZ M.
Published: November 2004

Condensed matter effects (CME) influence nuclear fusion rates in astrophysical settings. As potential energy is a significant component of the total energy in dense plasmas or condensed matter, the mean kinetic energy (and hence effective flux velocity) is reduced. Additional CME are due to a high density interference effect. Both CME reduce the flux in elastic scattering with a significantly larger reduction in fusion rates for the higher Z nuclei. Our CME predictions are consistent with neutrino experiments including the recent GALLEX measurements. CME have broad ranging astrophysical implications, and may be testable in laboratory beam fusion experiments with solid targets.
NMR IN A SYSTEM OF SMALL METALLIC PARTICLES: A NOVEL MESOSCOPIC PHENOMENON
Authors: EFETOV K.B. , PRIGODIN V.N.
Published: November 2004

We consider the NMR line shape for a system of small metal particles. The problem is reduced to calculation of the local density of states distribution function. We present the first exact calculation of this quantity for the mesoscopic system. Using the super-symmetry method, we calculated exactly the whole distribution function which gives the resonance-line shape. It turns out that at low temperatures, the line becomes very broad and asymmetric. The Knight shift defined as the maximum of the line decreases when decreasing the temperature. We found a good agreement of our results with a few experiments done long ago.
STUDY OF PINNING BEHAVIOR OF VORTEX LATTICE IN Bi1.6Pb0.3W0.1Sr2Ca2Cu3Oy SUPERCONDUCTING SYSTEM
Authors: RAO G. NARSINGA , BABU D. SURESH , MOLINIE P. , GANNE M.
Published: November 2004

We report characterization and detailed magnetization study in fields up to 2 T in the temperature range between 5 and 80 K of Bi 1.6 Pb 0.3 W 0.1 Sr 2 Ca 2 Cu 3 O y (nominal composition pellets). XRD, field-cooled magnetization measurements, and electrical resistance studies showed that the sample consists of a single phase high-Tc (Bi-2223) superconductor in addition to CaWO y-type impurity. An empirical magnetic phase diagram of the superconducting system has been derived. We determined a H*(T) line where Jc becomes zero. In the region with nonzero critical current density, vortex lattice exhibits mainly two types of pinning behaviours, single vortex and collective pinning behaviour, in different field and temperature range. In addition, the temperature dependence of Jc showed an evidence of two types of pinning centres. In low temperatures (<40 K), the pinning centers with low values of activation energy are active whereas in high temperatures (≥40 K), the pinning centers with larger activation energy are active. These results are compared with those of Job & Rosenberg1 on Bi-2223 ceramic samples.
THE REFRACTIVE INDEX AT THE CENTER OF THE SURFACE OF PRESSURIZED DIAMOND ANVIL TIPS
Authors: RUOFF ARTHUR L. , GHANDEHARI KOUROS
Published: November 2004

An expression for the variation of the refractive index of diamond with density is determined. This is used to show consistency between Brillouin scattering results obtained at atmospheric pressure and more recent direct measurements of the refractive index under hydrostatic pressure to 40 GPa. The stress distribution at the diamond anvil tip is then computed and the variation of the refractive index at the tip of the anvil is obtained. The refractive index at the tip is a slowly decreasing function of the sample pressure.
MANY-ELECTRON SCREENING EFFECT ON THE STABILITY CRITERIA OF AN ALL-COUPLING OPTICAL BIPOLARON IN TWO DIMENSIONS
Authors: CHATTERJEE ASHOK , SIL SHREEKANTHA
Published: November 2004

We perform an all-coupling variational calculation to study the many-electron screening effect on the stability criteria of a two-dimensional singlet optical bipolaron. We also show how the effective mass and the size of the bipolaron would depend on the carrier concentration.
INTRINSIC QUASIPARTICLE’S SPIN AND FRACTIONAL QUANTUM HALL EFFECT ON RIEMANN SURFACES
Authors: LI DINGPING
Published: November 2004

We derive the braid relations of the charged anyons interacting with a magnetic field on Riemann surfaces. The braid relations are used to calculate the quasiparticle’s spin in the fractional quantum Hall states on Riemann surfaces. The quasiparticle’s spin is found to be topologically independent and satisfies physical restrictions.
SHOT NOISES IN A CORRELATED TUNNELING CURRENT
Authors: GALPERIN YU. M. , HANKE ULRIK , CHAO K. A. , ZOU NANZHI
Published: November 2004

An analytical expression for shot noises in a correlated sequential tunneling current has been derived by solving the Master equation exactly. The existing result for the simplest case of Pauli correlation is easily reproduced. Our theory is applied to the Coulomb blockade single-electron tunneling system with two tunnel junctions. Given capacitances and resistances of the system, both the suppressed zero-frequency shot noise and the entire finite-frequency noise spectrum are obtained, which are much more complicated than the simplest Pauli correlation case. Our theoretical predictions, after being confirmed experimentally, will introduce the noise spectroscopy as a tool to investigate correlated tunneling current.
PROPOSAL FOR MEASURING FRACTIONAL CHARGE OF QUASIPARTICLES WITH QUANTUM HALL-STATE JOSEPHSON EFFECT
Authors: EZAWA Z. F. , IWAZAKI A. , WU YONG-SHI
Published: November 2004

We propose a way to measure the fractional charge of quasiparticles by exploiting the dc Josephson effect that is predicted to exist in certain double-layer quantum Hall systems.
STATISTICAL PROPERTIES OF PHONONS IN POLARITON-LIKE SYSTEM AT EQUILIBRIUM
Authors: CHIZHOV A. V. , GOVORKOV B. B. , SHUMOVSKY A. S.
Published: November 2004

The quantum fluctuations of the number of phonons at thermal equilibrium in a polariton-like system are investigated. The fluctuations are shown to possess a super-Gaussian character. It is suggested a possible way of measuring these fluctuations.
STUDIES ON Bi1.7Pb0.3Sr2Ca2Cu3Oy TREATED IN AIR, OXYGEN, AND ARGON GASES
Authors: NARSINGA RAO G. , SUBHASH P. , BABU D. SURESH , GANNE M.
Published: November 2004

We present an investigation of Bi 1.7 Pb 0.3 Sr 2 Ca 2 Cu 3 O y system, treated in air, argon, and oxygen gaseous environment, by combination of XRD, SEM, electrical resistivity, and ac susceptibility measurements. XRD data of all the samples showed a presence of both 2212 and 2223 phases in the sample. As prepared sample showed a single transition temperature at 109 K in both ac susceptibility and electrical resistivity measurements. Samples treated in oxygen showed a single transition at 107 K in ac susceptibility measurements and at 104 K in resistivity measurements, whereas samples treated in argon had two transitions at 107 K and 85 K in ac susceptibility data and a single transition at 102 K in resistivity measurements. These results were explained in terms of coupling between grains. Intragrain critical current density of As grown sample was estimated.
THEORETICAL INVESTIGATIONS OF DELTA-DOPED INTERBAND RESONANT TUNNELING DIODE
Authors: SHENG HANYU , CHUA SOO-JIN
Published: November 2004

DC properties of the delta-doped interband resonant tunneling diode are studied by a simple semiclassical model based on the use of the velocity distribution functions fitted with the barrier reflection and transmission probabilities. Quantum interference is included by introducing a phase correlation function between the incoming waves. The effect of scattering on the quantum well is considered by the mean free path. The two-band theory is used to treat the interaction between the conduction band and the light-hole valence band. The results show that the peak-to-valley current ratio can reach up to as high as 20 at room temperature for GaAs material.
ULTRASONIC ANOMALIES IN Y–Ba–Cu–O HIGH-Tc SUPERCONDUCTING MATERIALS
Authors: REDDY P. VENUGOPAL , REDDY R. RAVINDER , REDDY K. BHUPAL , MULAY V. N.
Published: November 2004

The longitudinal and shear wave velocities of Y–1–2–3 superconducting materials prepared by the sol–gel method have been measured by the pulse transmission technique over a temperature range of 80–300 K. The longitudinal velocity of both the samples, in general, is found to vary in an anomalous way. The observed behaviour has been explained qualitatively on the basis of a model.
MAGNETIC INTERACTION IN ALUMINOSILICATE GLASSES CONTAINING MANGANESE IONS
Authors: RANA MAZHAR UDDIN
Published: November 2004

By measuring the magnetic susceptibilities, the magnetic interaction between manganese ions has been investigated in manganese aluminosilicate glasses over a temperature range of 1.5–150 K of composition (MnO) x( Al 2 O 3 SiO 2)1−x with 0<x<0.51. A simple structure model is used to explain the interaction between the manganese ions. The effective magnetic moment per magnetic ion was calculated to lie between 5.64 and 6.03 µ B .
LIQUID CRYSTAL EQUILIBRIUM FLUCTUATIONS UNDERSTOOD BY A RELATIONSHIP TO THE DYNAMICS OF GROWING INTERFACES
Authors: GOLUBOVIĆ LEONARDO
Published: November 2004

We review a recent theoretical progress in understanding equilibrium thermal fluctuations of smectic A liquid crystals. It is based on a relationship of smectics A to a rather different physical problem, namely, the Kardar-Parisi-Zhang (KPZ) dynamical model for interfaces growing in the presence of a flux of incoming particles. This relationship provides an exact approach to study Landau-Peierls phenomena in two-dimensional smectics and reveals the existence of novel elastic critical point in three-dimensional smectics A with broken inversion symmetry.
THE INFLUENCE OF Pb, Ni AND V DOPING ON THE CHARACTERISTICS OF HIGH-TcBi-Si-Ca-Cu-O SUPERCONDUCTORS
Authors: KHAN M.N. , MEMON A. , AL-DALLAL S. , AL-OTHMAN M. , ZEIN M. , ALNASER W.
Published: November 2004

We report on the studies of ac susceptibility, ultrasonic attenuation, superconductivity and some calorimetric measurements on Pb -doped for Bi -site as well as Ni and V substitution for Cu in Bi-Sr-Ca-Cu-O superconductors.

It was confirmed that the Bi(Pb)-based glass ceramics (i.e. crystallized glasses) exhibit superconductivity with T c above 105 K higher than Bi(Ni) with Tc 68 K and Bi(V) -based glasses with T c 40K.

X-ray diffraction analysis revealed that the structure of these materials is Bi -2223 type with a=4.067 Å and C=30.768 Å.

It was found from the temperature dependence of ac complex susceptibility that the coupling nature at grain boundaries of superconducting crystals in the samples obtained was weak, and was improved by increasing the annealing time. Data are discussed for varying T c of different substituents.

Our results on the ultrasonic attenuation revealed a series of relaxation peaks with low activation enthalpies which indicate that electronic defects may be the cause for the relaxation processes.
ORDERING AND ORDERING TRANSITIONS IN CONFINED LIQUID CRYSTALS
Authors: CRAWFORD G.P. , DOANE J.W.
Published: November 2004

A resurgence of interest in confined liquid crystals has taken place over the past few years because of the availability of well-defined and random-type matrices that can be used to constrain liquid crystalline materials to submicrometer spaces. The main driving force behind many of the studies on confined liquid crystals is their relevance to electrically controllable light-scattering devices. Apart from their electrooptic importance, confined liquid crystals introduce many fascinating surface and finite-size effects which are the subject of this review.
BLACK-BODY RADIATION AND EINSTEIN’S TRANSITION PROBABILITY FOR q-BOSONS
Authors: HSU RUE-RON , LEE CHIN-RONG
Published: November 2004

We study the black-body radiation and Einstein’s law of transition probability in a q-boson system which obey the q-Heisenberg algebra.
NONEQUILIBRIUM PATTERN FORMATION INVOLVING BOTH CONSERVED AND NONCONSERVED ORDER PARAMETERS AND EFFECT OF LONG-RANGE INTERACTIONS
Authors: CHEN LONG-QING
Published: November 2004

Recent progress in the computer simulation of nonequilibrium and nonlinear morphological pattern formation involving two or more order parameters is reviewed. A computer simulation technique based on microscopic diffusion theory is presented and applied to the dynamics of simultaneous atomic ordering and compositional clustering in crystalline solid solutions. The effects of long-range elastic and Coulomb interactions on the morphological patterns are discussed.
HIGHLY DEFORMED q-OSCILLATOR SYSTEMS
Authors: -MONTEIRO MARCO A.R. , RODITI ITZHAK , RODRIGUES LIGIA M.C.S.
Published: November 2004

We consider the large q limit of systems made of deformed Heisenberg operators. When the deformation parameter is infinite the Fock space and the statistical properties have a fermionic behaviour. We also investigate the ideal q-gas and find the virial expansion of its equation of state.
SPONTANEOUS MAGNETIZATION OF THE ISING MODEL ON THE GENERAL UTIYAMA LATTICE
Authors: LEE S.F. , LIN K.Y.
Published: November 2004

The spontaneous magnetization of the two-dimensional Ising model on the general Utiyama lattice is derived exactly. Our results include the checkerboard, kagome, 4–8, and 3–12 lattices as special cases.
NEAR-COLLISIONS IN A COULOMB SYSTEM: NUMERICAL SIMULATIONS — A PRELUDE TO HYBRID FUSION
Authors: MENDES R. VILELA
Published: November 2004

In the microcanonical phase space of a classical Coulomb system with positive (D) and negative (e) particles, low-energy near-collisions of two positive particles are dominated by (DeD) configurations. Computed from the area of the energy hypersurface where these events take place, the probability for (DeD) near-collisions is many orders of magnitude above the probability for tunneling through the Coulomb barrier in a (DeD)+ bound state, when e is a light particle.

If the Coulomb system is embedded in a metallic lattice, access to the near-collision regions in the phase space is hindered by the regularity of the lattice. One should then expect, at most, intermittent and irreproducible behavior associated to mechanisms like Arnold’s diffusion. Mechanisms to restore ergodicity are proposed.

Numerical simulations are performed on a three-body system to compare the observed rate of near-collisions in actual orbits (with random initial conditions) with the phase-space estimates. It is found that local conservation of angular momentum causes large deviations from the phase-space estimates.
A FULLY AUTOMATED OFFLINE HANDWRITING RECOGNITION SYSTEM INCORPORATING RULE BASED NEURAL NETWORK VALIDATED SEGMENTATION AND HYBRID NEURAL NETWORK CLASSIFIER
Authors: GHOSH MOUMITA , GHOSH RANADHIR , VERMA BRIJESH
Published: November 2004

In this paper we propose a fully automated offline handwriting recognition system that incorporates rule based segmentation, contour based feature extraction, neural network validation, a hybrid neural network classifier and a hamming neural network lexicon. The work is based on our earlier promising results in this area using heuristic segmentation and contour based feature extraction. The segmentation is done using many heuristic based set of rules in an iterative manner and finally followed by a neural network validation system. The extraction of feature is performed using both contour and structure based feature extraction algorithm. The classification is performed by a hybrid neural network that incorporates a hybrid combination of evolutionary algorithm and matrix based solution method. Finally a hamming neural network is used as a lexicon. A benchmark dataset from CEDAR has been used for training and testing.
MULTIPLE CLASSIFIER SYSTEMS IN OFFLINE HANDWRITTEN WORD RECOGNITION — ON THE INFLUENCE OF TRAINING SET AND VOCABULARY SIZE
Authors: GÜNTER SIMON , BUNKE HORST
Published: November 2004

Handwritten text recognition is one of the most difficult problems in the field of pattern recognition. Recently, a number of classifier creation methods, known as ensemble methods, have been proposed in the field of machine learning. It has been shown that these methods are able to substantially improve recognition performance in complex classification tasks. In this paper we examine the influence of the vocabulary size and the number of training samples on the performance of three ensemble methods in the context of handwritten word recognition. The experiments were conducted with two different offline hidden Markov model based handwritten word recognizers.
AN EFFICIENT METHOD FOR ONLINE CURSIVE HANDWRITING STROKES REORDERING
Authors: DE STEFANO CLAUDIO , MARCELLI ANGELO
Published: November 2004

In the framework of online cursive handwriting recognition, we present an efficient method for reordering the sequence of strokes composing handwriting in two special cases of interest: the horizontal bar of the character "" and the dot of the character "". The proposed method exploits shape information for selecting the strokes that most likely correspond to the features of interest, and layout and topological information for locating the strokes representing the body of the characters to which the features belong to. The method does not depend on the specific algorithm used for detecting the elementary strokes in which the electronic ink may be decomposed into. The performance of our method, evaluated on a data set of cursive words produced by 50 different writers, has shown a correct reordering of the sequence in more than 85% of the cases. Thus, the proposed method allows obtaining a more stable and invariant description of the electronic ink in terms of elementary stroke sequences, and therefore can be helpfully used as a preprocessing step for both segmentation-based and word-based handwriting recognition systems.
A MINIMUM ERROR RATE PATTERN RECOGNITION APPROACH TO SPEECH RECOGNITION
Authors: CHOU W. , LEE C.-H. , JUANG B.-H. , SOONG F.K.
Published: November 2004

In this paper, a minimum error rate pattern recognition approach to speech recognition is studied with particular emphasis on the speech recognizer designs based on hidden Markov models (HMMs) and Viterbi decoding. This approach differs from the traditional maximum likelihood based approach in that the objective of the recognition error rate minimization is established through a specially designed loss function, and is not based on the assumptions made about the speech generation process. Various theoretical and practical issues concerning this minimum error rate pattern recognition approach in speech recognition are investigated. The formulation and the algorithmic structures of several minimum error rate training algorithms for an HMM-based speech recognizer are discussed. The tree-trellis based N-best decoding method and a robust speech recognition scheme based on the combined string models are described. This approach can be applied to large vocabulary, continuous speech recognition tasks and to speech recognizers using word or subword based speech recognition units. Various experimental results have shown that significant error rate reduction can be achieved through the proposed approach.
MACHINE LEARNING FOR OBJECT RECOGNITION AND SCENE ANALYSIS
Authors: KODRATOFF Y. , MOSCATELLI S.
Published: November 2004

Learning is a critical research field for autonomous computer vision systems. It can bring solutions to the knowledge acquisition bottleneck of image understanding systems. Recent developments of machine learning for computer vision are reported in this paper. We describe several different approaches for learning at different levels of the image understanding process, including learning 2-D shape models, learning strategic knowledge for optimizing model matching, learning for adaptive target recognition systems, knowledge acquisition of constraint rules for labelling and automatic parameter optimization for vision systems. Each approach will be commented on and its strong and weak points will be underlined. In conclusion we will suggest what could be the “ideal” learning system for vision.
UNSUPERVISED LEARNING OF PRIOR WEIGHTS FOR BAYES RULES IN PATTERN RECOGNITION
Authors: LI TZE FEN
Published: November 2004

In the pattern classification problem, it is known that the Bayes decision rule, which separates k classes, gives a minimum probability of misclassification. In this study, the prior probability of each class is unknown and the conditional density functions are known. A set of unidentified input patterns is used to establish an empirical Bayes rule, which separates k classes and which leads to a stochastic approximation procedure for estimation of the priors. This classifier can adapt itself to a better decision rule by making use of unidentified input patterns while the system is in use. The resulting probability of misclassification can be made arbitrarily close to that of the Bayes rule. The results of a Monte Carlo simulation study with normal, uniform and exponential distributions are presented to demonstrate the favorable prior estimation for the empirical Bayes rule.
MANIPULATIONS OF OCTREES AND QUADTREES ON MULTIPROCESSORS
Authors: CHAUDHARY VIPIN , KUMARI K. , ARUNACHALAM P. , AGGARWAL J.K.
Published: November 2004

Octrees offer a powerful means for representing and manipulating 3-D objects. This paper presents an implementation of octree manipulations using a new approach on a shared memory architecture. Octrees are hierarchical data structures used to model 3-D objects. The manipulation of these data structures involves performing independent computations on each node of the octree. Octrees are much easier to deal with than other forms of representations used to model 3-D objects especially where extensive manipulations are involved. When these operations are distributed among multiple processing elements (PEs) and executed simultaneously, a significant speedup may be achieved. Manipulations such as a complement, a union, an intersection and other operations such as finding the volume and centroid which this paper describes are implemented on the Sequent Balance multiprocessor. In this approach the PEs are allocated dynamically, resulting in a uniform load balancing among them. The experimental results presented illustrate the feasibility of the approach. Although this evaluation has been originally done for shared memory machines, it will provide insight for the evaluation of other architectures.
PARALLEL ALGORITHMS FOR MULTIDIMENSIONAL IMAGE TEMPLATE MATCHING
Authors: SAOUDI A. , NIVAT M.
Published: November 2004

This paper presents efficient and optimal parallel algorithms for multidimensional image template matching on CREW PRAM model. For an Nd image and an Md window, we present an optimal (respectively efficient) algorithm which runs in O(log(M)) time with O(Md×Nd/log(M) processors (respectively O(Md×Nd)). We also present efficient and optimal algorithms for solving the multidimensional array and pattern matching.
MESH ALGORITHMS FOR FINDING REPETITIONS AND PARTIAL SYMMETRIES IN ARRAYS
Authors: TANIMOTO STEVEN L. , MILLER RUSS
Published: November 2004

The two-dimensional mesh computer architecture has proven to be an appropriate means to apply parallel computation to problems in image processing. However, this is most often done using local-neighbourhood operations to accomplish image filtering and morphological transformations. The discovery of structures in an image such as repetitions and symmetries is another form of visual analysis, and yet relatively little has been done to apply mesh computers to this problem. In this paper, we apply the primitive operations of prefix scanning and sorting to efficiently implement a repetition finding algorithm for arrays. The computational complexity of the algorithm on a n×n mesh is O(n log k) where k is the width of the largest repeated block in the array. The algorithm was implemented on a MasPar MP-1 computer. We describe variations of the algorithm for solving several related problems including the detection of partial symmetries in an image and repetitions in images modulo pixel-value transformations.
PARALLEL GENERATION AND PARSING OF ARRAY LANGUAGES USING REVERSIBLE CELLULAR AUTOMATA
Authors: MORITA KENICHI , UENO SATOSHI
Published: November 2004

We propose a new system of generating array languages in parallel, based on a partitioned cellular automaton (PCA), a kind of cellular automaton. This system is called a PCA array generator (PCAAG). The characteristic of PCAAG is that a”reversible” version is easily defined. A reversible PCA (RPCA) is a backward deterministic PCA, and we can construct a deterministic “inverse” PCA that undoes the operations of the RPCA. Thus if an array language is generated by an RPCA, it can be parsed in parallel by a deterministic inverse PCA without backtracking. We also define two subclasses of PCAAG, and give examples of them that generate geometrical figures.
USE OF GRADATED PATTERNS IN AN ASSOCIATIVE NEURAL MEMORY FOR INVARIANT PATTERN RECOGNITION
Authors: KOBARA KAZUKUNI , KANAOKA TAIHO , HAMAMOTO YOSHIHIKO , TOMITA SHINGO , MUNECHIKA KOUKICHI
Published: November 2004

Distortion invariant pattern recognition is an interesting problem from the biological and technological point of view. However, it has not yet been solved by neural networks in satisfactory way. This paper investigates an associative neural network system to improve the recalling accuracy for distortion patterns. On a perception type of neural network with feedback, error back-propagation algorithm and energy function are used for a learning process and a recalling process, respectively. By using gradated patterns as learning and unknown patterns, it is shown that the recalling accuracy becomes higher than using original pattern themselves.
A STATIC SIGNATURE VERIFICATION SYSTEM BASED ON A COOPERATING NEURAL NETWORKS ARCHITECTURE
Authors: CARDOT HUBERT , REVENU MARINETTE , VICTORRI BERNARD , REVILLET MARIE-JOSÈPHE
Published: November 2004

We are applying neural networks to the problem of handwritten signature verification. Our system is working on checks, so we can only use the static information (the image). This static information is used in three representations: geometrical parameters, outline and image. Our system is composed of several neural networks which cooperate together during the learning and decision phases. The performances in generalization, obtained with a large-scale database of 6000 signatures from real checks on random forgeries, are False Acceptance Rate (FAR)=2% and False Rejection Rate (FRR)=4%.
RANGE ESTIMATION FROM CAMERA BLUR BY REGULARIZED ADAPTIVE IDENTIFICATION
Authors: HOLEVA LEE F.
Published: November 2004

One of the fundamental problems of machine vision is the estimation of object depth from perceived images. This paper describes both an apparatus and the corresponding algorithms for the passive extraction of object depth. Here passive extraction implies the processing of images acquired using only the existing illumination, in this case roughly uniform white light.

Depth from defocused algorithms are extremely sensitive to image variations. Regularization, the application of a priori constraints, is employed to improve the accuracy of the range measurements. When the camera’s point spread function is shift invariant, an adaptive algorithm is developed in the frequency domain. The constraints imposed upon the solution power spectrum vector vary temporally. When the camera’s point spread function is shift varying, an adaptive algorithm is developed in the spatial domain. The constraints imposed upon the solution point spread vector vary spatially.

Data is acquired from line scan cameras. Only a single range measurement or a single depth profile is extracted. By relying upon the motion of the observed object on a conveyor belt, a complete range image may be generated.
MODELING SENSOR CONFIDENCE FOR SENSOR INTEGRATION TASKS
Authors: HUGHES KEN , RANGANATHAN N.
Published: November 2004

This paper addresses the problem of determining the reliability of individual sensors in a multi-sensor robotic system in an unknown environment. The inherent difficulty in this problem is that the decision must be based solely upon the data from the sensors themselves. While some previous research has considered unstructured environments (see Refs. 1 and 2 for examples) little if any consideration has been given to totally unknown environments. This problem has usually been avoided by assuming that the sensors would not provide erroneous data or ignoring sensors when they appeared to provide erroneous data. We believe a more robust solution is to consider each sensor’s performance over time compared to other sensors, and from this determine a measure of confidence in each sensor. This allows sensors which temporarily provide erroneous data to be accommodated. A system which can determine the reliability of its sensors is more robust since it can wisely decide which sensors are most appropriate for a given task and can also determine whether sensor conflicts are the result of poorly performing sensors.
LOCALLY IMPLEMENTABLE MATRIX FLOWS AND THEIR APPLICATION TO NEURAL NETWORK LEARNING
Authors: DEHAENE JEROEN , VANDEWALLE JOOS
Published: November 2004

A number of matrix flows, based on isospectral and isodirectional flows, is studied and modified for the purpose of local implementability on a network structure. The flows converge to matrices with a predefined spectrum and eigenvectors which are determined by an external signal. The flows can be useful for adaptive signal processing applications and are applied to neural network learning.
CHUA’S CIRCUIT: AN OVERVIEW TEN YEARS LATER
Authors: CHUA LEON O.
Published: November 2004

More than 200 papers, two special issues (Journal of Circuits, Systems, and Computers, March, June, 1993, and IEEE Trans. on Circuits and Systems, vol. 40, no. 10, October, 1993), an International Workshop on Chua’s Circuit: chaotic phenomena and applica tions at NOLTA’93, and a book (edited by R.N. Madan, World Scientific, 1993) on Chua’s circuit have been published since its inception a decade ago. This review paper attempts to present an overview of these timely publications, almost all within the last six months, and to identify four milestones of this very active research area.

An important milestone is the recent fabrication of a monolithic Chua’s circuit. The robustness of this IC chip demonstrates that an array of Chua’s circuits can also be fabricated into a monolithic chip, thereby opening the floodgate to many unconventional applications in information technology, synergetics, and even music.

The second milestone is the recent global unfolding of Chua’s circuit, obtained by adding a linear resistor in series with the inductor to obtain a canonical Chua’s circuit— now generally referred to as Chua’s oscillator. This circuit is most significant because it is structurally the simplest (it contains only 6 circuit elements) but dynamically the most complex among all nonlinear circuits and systems described by a 21-parameter family of continuous odd-symmetric piecewise-linear vector fields.

The third milestone is the recent discovery of several important new phenomena in Chua’s circuits, e.g., stochastic resonance, chaos-chaos type intermittency, 1/f noise spectrum, etc. These new phenomena could have far-reaching theoretical and practical significance.

The fourth milestone is the theoretical and experimental demonstration that Chua’s circuit can be easily controlled from a chaotic regime to a prescribed periodic or constant orbit, or it can be synchronized with 2 or more identical Chua’s circuits, operating in an oscillatory, or a chaotic regime. These recent breakthroughs have ushered in a new era where chaos is deliberately created and exploited for unconventional applications, e.g. secure communication.
A CONTRACTION ALGORITHM FOR FINDING ALL THE DC SOLUTIONS OF PIECEWISE-LINEAR CIRCUITS
Authors: TADEUSIEWICZ MICHAL , GŁOWIENKA KRZYSZTOF
Published: November 2004

An efficient algorithm for finding all the DC solutions of a broad class of piecewise-linear circuits, having hybrid representation, is described in this paper. Circuits belonging to this class can include electronic devices modelled by linear resistors, linear controlled sources, piecewise-linear two terminal resistors and independent sources. The algorithm is based on the idea of successive division and contraction of the solution domain. Two contraction methods are developed that result in a high rate of convergence of the computation process. Numerical examples and comparison analyses show the efficiency of this algorithm.
DIGITALLY CONTROLLED FLOW METERING UNIT WITH DOUBLE ACTUATION FOR FAST TRANSIENT RESPONSE IN AUTOMOTIVE APPLICATIONS
Authors: KREPEC T. , GEORGANTAS A.I.
Published: November 2004

This paper proposes a novel compact, inexpensive, yet versatile flow metering unit which consists of two hydraulic valves incorporated in a single barrel and operated directly by two digital actuators. For the evaluation of the concept, the mathematical model of the unit is developed and validated. The model is subsequently used to investigate the operability and performance of the system. A specific control strategy taking advantage of the system hardware is implemented. The enhancement of the transient response, as compared to single actuation conventional units, is demonstrated. Furthermore, the back-up functionality in case of failure of one of the valves is ascertained. This kind of double actuator unit is proposed for, but not limited to, fuel metering in a gasoline engine throttle body injection system.
DYNAMIC PERFORMANCE OF MCTs UNDER INDUCTIVE LOAD CONDITIONS
Authors: KAZIMIERCZUK MARIAN K. , THIRUNARAYAN NANDAKUMAR
Published: November 2004

PMOS-controlled thyristors (PMCTs) were tested in a single-switch configuration under inductive-load hard-switching conditions. The transient current and voltage waveforms during the turn-on and turn-off transitions were observed for 50 A/1000 V devices. The experimental waveforms are given for the anode current, the inductor current, the anode-to-cathode voltage, and the gate-to-anode drive voltage. These waveforms were obtained for periodic gate drive voltage at 6.5 kHz. The test circuit was operated at power levels of up to 370 W. The measured turn-on time was 0.255 μs at an anode-to-cathode voltage of 270 V and the measured turn-off time was 1.6 μs at an anode current of 16 A. The measured storage time was 1 μs. The measured input capacitance of the MCT was 13.5 nF and the output capacitance was 66.7 nF. It was found that the input and output capacitances of PMCTs are approximately linear.
Z-θ MOTION ACTUATOR WITH INTERIOR PERMANENT MAGNET MOVER
Authors: SANADA MASAYUKI , MORIMOTO SHIGEO , TAKEDA YOJI
Published: November 2004

The linear pulse motor (LPM) can operate in an open-loop control mode similar to a rotary stepper motor, and it has large thrust in small input power and volume comparing with other linear motors. We proposed a new cylindrical linear pulse motor with an interior permanent magnet mover (IPMM-LPM), which has no thrust imbalance theoretically. The IPMM-LPM has the same mover cross section in comparison with the permanent magnet synchronous motor. Therefore, by only making an addition of an armature winding for the synchronous motor to the IPMM-LPM, the IPMM-LPM has an ability of a rotary motion as well as linear motion.

In this paper, the new Z-θ motion actuator, which not only has the ability of linear motion but also rotary motion, is proposed and basic characteristics are examined in detail based on calculated and experimental results. The proposed Z-θ motion actuator is useful for machine tools such as a lathe and so forth.
ANALYTIC METHODS FOR SOLITON SYSTEMS
Authors: LAKSHMANAN M.
Published: November 2004

The study of soliton systems continues to be a highly rewarding exercise in nonlinear dynamics, even though it has been almost thirty years since the introduction of the soliton concept by Zabusky & Kruskal. Increasingly sophisticated mathematical concepts are being identified with integrable soliton systems, while newer applications are being made frequently. In this pedagogical review, after introducing solitons and their (2+1)-dimensional generalizations, we give an elementary discussion on the various analytic methods available for investigation of the soliton possessing nonlinear evolution equations. These include the inverse scattering transform method and its generalization, namely the d-bar approach, for solving the Cauchy initial value problem, as well as direct methods for obtaining N-soliton solutions. We also indicate how the Painlevé singularity structure analysis is useful for the detection of soliton systems.
HIGHER-ORDER SPECTRAL ANALYSIS TO DETECT NONLINEAR INTERACTIONS IN MEASURED TIME SERIES AND AN APPLICATION TO CHUA’S CIRCUIT
Authors: ELGAR STEVE , CHANDRAN VINOD
Published: November 2004

Higher-order spectra have been used to investigate nonlinear interactions between the Fourier components of measured time series in a remarkably wide range of random processes. The basic techniques of detecting and isolating nonlinear phase coupling in observed data using higher-order spectral analysis are reviewed here. These techniques are then used to investigate nonlinear interactions in time series of voltages measured from a realization of Chua’s circuit. For period-doubled limit cycles, quadratic and cubic nonlinear interactions result in phase coupling and energy exchange between increasing numbers of triads and quartets of Fourier components as the nonlinearity of the system is increased. For circuit parameters that result in a chaotic, Rössler-type attractor, bicoherence and tricoherence spectra indicate that both quadratic and cubic nonlinear interactions are important to the dynamics. For parameters that lead to the double-scroll chaotic attractor the bispectrum is zero, but the tricoherences are high, consistent with the importance of higher-than-second order nonlinear interactions during chaos associated with the double scroll.
DIFFUSIVE EFFECTS ON A CATALYTIC SURFACE REACTION: AN INITIAL BOUNDARY VALUE PROBLEM IN REACTION-DIFFUSION-CONVECTION EQUATIONS
Authors: ZHANG WEN
Published: November 2004

A bimolecular catalytic surface reaction is extended to include diffusion which yields mobilized coverage on the surface. We consider the reaction occurring in a tubular reactor with a convection flow where the reactants also diffuse. An initial boundary value problem in one-dimensional reaction-diffusion-convection equations is used in describing the model. We combine singular perturbation analysis with numerical simulations in studying the solution behavior in parameter space. We track the reaction front and the cause of period-2 oscillations. Compared with the case of having no surface diffusion, we observe regular oscillations instead of irregular oscillations. Compared with the nondiffusive nonconvective model, we obtain rich spatiotemporal patterns including stationary, oscillatory reaction fronts and multiple steady states.
ELLIPTIC NON-BIRKHOFF PERIODIC ORBITS IN THE TWIST MAPS
Authors: OLVERA ARTURO , SIMÓ CARLES
Published: November 2004

We consider a perturbed twist map when the perturbation is big enough to destroy the invariant rotational curve (IRC) with a given irrational rotation number. Then an invariant Cantorian set appears. From another point of view, the destruction of the IRC is associated with the appearance of heteroclinic connections between hyperbolic periodic points. Furthermore the destruction of the IRC is also associated with the existence of non-Birkhoff orbits. In this paper we relate the different approaches.

In order to explain the creation of non-Birkhoff orbits, we provide qualitative and quantitative models. We show the existence of elliptic non-Birkhoff periodic orbits for an open set of values of the perturbative parameter. The bifurcations giving rise to the elliptic non-Birkhoff orbits and other related bifurcations are analysed. In the last section, we show a celestial mechanics example displaying the described behavior.