bluuebunny/crossref_metadata_2025 huggingface dataset:
SUFFICIENTLY SMALL $\bar\theta$inSU(3)3 × S3 UNIFICATION MODEL
Authors: CHALUT K. , CHENG H. , FRAMPTON P. H. , STOWE K. , YOSHIKAWA T.
Published: October 2002

Since CP violation in weak decays is successfully described by the KM mechanism, the strong CP problem cannot be easily accommodated. This leads us to reconsider the issue. If the axion and massless up quark are abandoned, we must extend the standard model. Extension to SU (3)3 × S3 unification leads to the following situation: if CP is a high-energy symmetry and the appropriate symmetry-breaking hierarchy of scales is in place, then the [Formula: see text] parameter of the QCD sub-theory is guaranteed to be sufficiently small. We find [Formula: see text] while the empirical limit from the neutron electric dipole moment requires only that [Formula: see text].
ALTERNATIVE HAMILTONIAN DESCRIPTIONS FOR QUANTUM SYSTEMS AND NON-HERMITIAN OPERATORS WITH REAL SPECTRUM
Authors: VENTRIGLIA FRANCO
Published: October 2002

Many problems in theoretical physics are very frequently dealt with non-Hermitian operators. Recently there has been a lot of interest in non-Hermitian operators with real spectra. In this paper, by using the inverse problem for quantum systems, we show that, on finite-dimensional Hilbert spaces, all diagonalizable operators with a real spectrum can be made Hermitian with respect to a properly chosen inner product. In particular this allows the use of standard methods of quantum mechanics to analyze non-Hermitian operators with real spectra.
SINGLE DIFFRACTIVE $\Lambda_c^+$ PRODUCTION IN POLARIZED pp SCATTERING WITH POLARIZED GLUON DISTRIBUTION IN THE PROTON
Authors: OHKUMA KAZUMASA , MORII TOSHIYUKI
Published: October 2002

Based on the hard-scattering factorization which decomposes the diffractive structure function into a pomeron flux and a pomeron structure function, we study the single diffractive [Formula: see text] production in polarized pp scattering: [Formula: see text], which will be observed at forthcoming RHIC experiment. By analyzing the cross-section and correlation of the spin polarization between the initial proton and produced [Formula: see text], we found that the process might be effective for testing both hard-scattering factorization and models of the polarized gluon distribution in the proton.
RESONANCE SOLITONS AS BLACK HOLES IN MADELUNG FLUID
Authors: PASHAEV O. K. , LEE JYH-HAO
Published: October 2002

Envelope solitons of the Nonlinear Schrödinger equation (NLS) under quantum potential's influence are studied. Corresponding problem is found to be integrable for an arbitrary strength, s ≠ 1, of the quantum potential. For s < 1, the model is equivalent to the usual NLS with rescaled coupling constant, while for s > 1, to the reaction–diffusion system. The last one is related to the anti-de Sitter (AdS) space valued Heisenberg model, realizing a particular gauge fixing condition of the (1+1)-dimensional Jackiw–Teitelboim gravity. For this gravity model, by the Madelung fluid representation we derive the acoustic form of the space–time metric. The space–time points, where dispersion changes the sign, correspond to the event horizon, while the soliton solution to the AdS black hole. Moving with the above bounded velocity, it describes evolution on the one sheet hyperboloid with nontrivial winding number, and creates under collision, the resonance states which we study by the Hirota bilinear method.
COSMIC STRINGS AND ENERGY MINING FROM BLACK HOLES
Authors: FROLOV VALERI
Published: October 2002

We discuss the mechanism of energy mining from black holes by cosmic strings and its efficiency.
LIGHT PROPAGATION IN GENERALLY COVARIANT ELECTRODYNAMICS AND THE FRESNEL EQUATION
Authors: HEHL FRIEDRICH W. , OBUKHOV YURI N. , RUBILAR GUILLERMO F.
Published: October 2002

Within the framework of generally covariant (pre-metric) electrodynamics, we specify a local vacuum spacetime relation between the excitation [Formula: see text] and the field strength F = (E,B). We study the propagation of electromagnetic waves in such a spacetime by Hadamard's method and arrive, with the constitutive tensor density κ ~ ∂H/∂F, at a Fresnel equation which is algebraic of 4th order in the wave covector. We determine how the different pieces of κ, in particular the axion and the skewon pieces, affect the propagation of light.
GRAVITATIONAL AND COSMOLOGICAL PROPERTIES OF A BRANE-UNIVERSE
Authors: LANGLOIS DAVID
Published: October 2002

The aim of this contribution is to provide a short introduction to recently investigated models in which our accessible universe is a four-dimensional submanifold, or brane, embedded in a higher dimensional spacetime and ordinary matter is trapped in the brane. I focus here on the gravitational and cosmological aspects of such models with a single extra-dimension.
COMPUTER ALGEBRA IN GENERAL RELATIVITY
Authors: MACCALLUM M. A. H.
Published: October 2002

This paper gives a short review of the status and applications of computer algebra systems for calculations in relativity and gravitation.
GAMMA-RAY BURSTS
Authors: PIRAN TSVI
Published: October 2002

Gamma-Ray Bursts (GRBs) are the most relativistic objects discovered so far. I describe here two aspects of the relativistic nature of GRBs. Their likely association with the formation of black holes and their possible role as sources of gravitational radiation.
APPROXIMATE SOLUTIONS OF TYPES (3, 1) AND (4)
Authors: ROBINSON IVOR , DOWNES PHILIP , MACALEVEY PAUL , NIŢĂ BOGDAN
Published: October 2002

A class of solutions to the Bianchi identities in linearized gravitational theory is given which includes fields which vanish asymptotically and are nowhere singular.
ROBINSON MANIFOLDS AND THE SHEAR-FREE CONDITION
Authors: TRAUTMAN ANDRZEJ
Published: October 2002

This paper is a short summary of the talk on Robinson manifolds and Cauchy–Riemann spaces given at Journées Relativistes 2001 in Dublin. It recalls two generalizations of the definition of shear-free congruences of null geodesics. These generalizations are equivalent in dimension 4, but not in higher dimensions, as illustrated on an example described by Ivor Robinson during that conference.
HIGHER DIMENSIONAL INHOMOGENEOUS DUST COLLAPSE AND COSMIC CENSORSHIP
Authors: BEESHAM A.
Published: October 2002

The singularity theorems of general relativity predict that gravitational collapse finally ends up in a spacetime singularity1. The cosmic censorship hypothesis (CCH) states that such a singularity is covered by an event horizon2. Despite much effort, there is no rigorous formulation or proof of the CCH. In view of this, examples that appear to violate the CCH and lead to naked singularities, in which non-spacelike curves can emerge, rather than black holes, are important to shed more light on the issue. We have studied several collapse scenarios which can lead to both situations3. In the case of the Vaidya-de Sitter spacetime4, we have shown that the naked singularities that arise are of the strong curvature type. Both types of singularities can also arise in higher dimensional Vaidya and Tolman-Bondi spacetimes, but black holes are favoured in some sense by the higher dimensions. The charged Vaidya-de Sitter spacetime also exhibits both types of singularities5.
PERTURBATIONS OF A CYLINDRICAL VORTEX IN A RELATIVISTIC PERFECT ISENTROPIC FLUID AND NAMBU GOTO DYNAMICS
Authors: BOISSEAU B.
Published: October 2002

The motion of the relativistic vortices has in general been studied in the context of a model based on non-linear wave equations of a complex scalar field. These studies have enlightened the theoretical similarities between superfluid vortices and global cosmic strings1-5. In this work we take a purely hydrodynamical point of view6. By a weak deformation of the cylindrical symmetry of a potential vortex in a relativistic perfect isentropic fluid, we study the possible dynamics of the central line of this vortex. In "stiff" material the Nambu-Goto equations are obtained7.
WORMHOLES AND SPACE–TIME FOAM: THE CASE WITH A COSMOLOGICAL CONSTANT
Authors: GARATTINI R.
Published: October 2002

We consider the computation of the energy difference between spaces having the same asymptotic behavior. Following the example of the Schwarzschild case which asymptotically tends to flat space1,2, we consider the case of a cosmological constant. The analysis is realized by means of variational methods in a Hamiltonian formulation and it is restricted to transverse-traceless (TT) tensors to one loop approximation. In particular, we consider the Schwarzschild-Anti-de Sitter (S-AdS) case which asymptotically tends to the Anti-de Sitter space and the Schwarzschild-de Sitter (SdS) case which asymptotically tends to the de Sitter space3,4. In both cases (S-AdS, SdS), we discover the existence of an unstable mode at zero temperature. This result leads to consider a different vacuum space which differs in a case to case. The configuration is stabilized by allowing N copies of the same initial system to contribute to the final energy5. A selection rule for different scenarios of a foam-like space can be given in terms of transition frequencies of the emitted radiation of a black hole6.
COVARIANT CONFORMAL DECOMPOSITION OF EINSTEIN EQUATIONS
Authors: GOURGOULHON E. , NOVAK J.
Published: October 2002

It has been shown1,2 that the usual 3+1 form of Einstein's equations may be ill-posed. This result has been previously observed in numerical simulations3,4. We present a 3+1 type formalism inspired by these works to decompose Einstein's equations. This decomposition is motivated by the aim of stable numerical implementation and resolution of the equations. We introduce the conformal 3-"metric" (scaled by the determinant of the usual 3-metric) which is a tensor density of weight -2/3. The Einstein equations are then derived in terms of this "metric", of the conformal extrinsic curvature and in terms of the associated derivative. We also introduce a flat 3-metric (the asymptotic metric for isolated systems) and the associated derivative. Finally, the generalized Dirac gauge (introduced by Smarr and York5) is used in this formalism and some examples of formulation of Einstein's equations are shown.
RADIATION GENERATED BY THE INFALL OF A SCALAR PARTICLE IN A SCHWARZSCHILD–ANTI-DE SITTER BACKGROUND
Authors: LEMOS JOSÉ P. S. , CARDOSO VITOR
Published: October 2002

In the context of the AdS/CFT conjecture1, a Schwarzschild-anti-de Sitter (SAdS) black hole may be looked at as a thermal state in the CFT. Perturbing the black hole corresponds in the CFT to perturb the thermal state. We considered an important specific perturbation - the radial infall of a small test particle coupled to a scalar field into a SAdS black hole. We computed the spectra, waveforms and total scalar energy radiated during this process. For small black holes, the spectra is dominated by a resonance, and the waveform by quasinormal ringing2,3,4. For large black holes we find that the waveform quickly settles down to its final zero value, always in a quasinormal way. The approach to thermal equilibrium in the CFT is therefore dictated by the lowest quasinormal frequency. We also commented on the interpretation of the bulk process when viewed from the brane: to the black hole corresponds a thermal bath, to the infalling probe corresponds an expanding bubble, and to the scalar field waves correspond particles decaying into bosons of the associate operator of the gauge theory. For more details see5,6.
WEAK SOLUTIONS FOR WEAK SINGULARITIES
Authors: NOLAN B. C.
Published: October 2002

We revisit the problem of the development of singularities in the gravitational collapse of an inhomogeneous dust sphere. As shown by Yodzis et al1, naked singularities may occur at finite radius where shells of dust cross one another. These singularities are gravitationally weak 2, and it has been claimed that at these singularities, the metric may be written in continuous form 2, with locally L∞ connection coefficients 3. We correct these claims, and show how the field equations may be reformulated as a first order, quasi-linear, non-conservative, non-strictly hyperbolic system. We discuss existence and uniqueness of generalized solutions of this system using bounded functions of bounded variation (BV) 4, where the product of a BV function and the derivative of another BV function may be interpreted as a locally finite measure. The solutions obtained provide a dynamical extension to the future of the singularity.
A NON-STANDARD COSMOLOGICAL MODEL
Authors: PUETZFELD D.
Published: October 2002

A non-standard cosmological model in Weyl-Cartan spacetime was presented1. Within this model the non-Riemannian quantities, i.e. torsion Tα and nonmetricity Qαβ, are proportional to the Weyl 1-form. The hypermomentum Δαβ depends on our ansatz for the nonmetricity and vice versa. In contrast to earlier investigations2 this model incorporates an additional quadratic nonmetricity term in the gauge Lagrangian, the Lagrangian under consideration reads [Formula: see text] We derived the explicit form of the field equations for different cases and provided solutions for a broad class of parameters. It was demonstrated that it is possible to construct models in which the non-Riemannian quantities die out with time. We showed how our model fits into the more general framework of metric-affine gravity (MAG)3. Additionally, we presented some preliminary results from our search for the best-fit parameters4 which was performed by using recent type Ia supernova data5.
WEAK SINGULARITIES IN GENERAL RELATIVITY
Authors: VICKERS J. A.
Published: October 2002

According to the Cosmic Censorship hypothesis realistic singularities should be hidden by an event horizon. However there are many examples of physically realistic space–times which are geodesically incomplete, and hence possess singularities according to the usual definition, which are not inside an event horizon. Many of these counterexamples to the cosmic censorship conjecture have a curvature tensor which is reasonably behaved (for example bounded or integrable) as one approaches the singularity. We give a class of weak singularities which may be described as having distributional curvature1. Because of the non–linear nature of Einstein's equations such distributional geometries are described using a diffeomorphism invariant theory of non–linear generalised functions2. We also investigate the propagation of test fields on space–times with weak singularities. We give a class of singularities3,4 which do not disrupt the Cauchy development of test fields and result in space–times which satisfy Clarke's criterion of 'generalised hyperbolicity'. We consider that points which are well behaved in this way, and where Einstein's equations make sense distributionally, should be regarded as interior points of the space–time rather than counterexamples to cosmic censorship.
Quarkonium Production at LEP with the OPAL Detector
Authors: Odorici F. , Ros E.
Published: October 2002

Evidence for the production of ϒ mesons in hadronic Z0 decays has recently been reported by the OPAL experiment at LEP. ϒ mesons are identified from their decays into e+e- and μ+μ- pairs. These decays provide a clear signature, since the e+e- and μ+ μ- background with invariant mass around 10 GeV/c2 is found to be small. In the first part of this report, a summary of the ϒ analysis is presented and possible production mechanisms are discussed. In the second part, studies on charmonium production are presented. Charmonium studies are based on an inclusive sample of J/ψ candidates, used to derive inclusive J/ψ and ψ′ rates, and the prompt J/ψ rate as well. Finally, since prompt J/ψ mesons are expected to be produced at LEP by the same production mechanisms as for the ϒ, a more general discussion on quarkonium production via fragmentation processes is presented.
Quarkonium Production at Z0 and in ϒ(1S) Decay
Authors: Cheung Kingman , Keung Wai-Yee , Yuan Tzu Chiang
Published: October 2002

The conventional color-singlet model was challenged by the recent data on quarkonium production. Discrepancies in production rates were observed at the Tevatron, at LEP, and in fixed-target experiments. The newly advocated color-octet mechanism provides a plausible solution to the anomalous quarkonium production observed at the Tevatron. The color-octet mechanism should also affect other quarkonium production channels. In this paper we will summarize the studies of quarkonium production in Z0 and ϒ decays.
Quarkonium Production: Velocity-Scaling Rules and Long-Distance Matrix Elements
Authors: Schuler Gerhard A.
Published: October 2002

The hierarchy of long-distance matrix elements (MEs) for quarkonium production depends on their scaling with the velocity v of the heavy quark in the bound state. Ranges for the velocities in various bound states and uncertainties of colour-singlet MEs are estimated in a quark-potential model. Different possibilities for the scaling with v of the MEs are discussed; they depend on the actual values of v and the QCD scale. As an application, J/ψ polarization in e+e- annihilation is discussed. The first non-perturbative estimates of colour-octet MEs are presented and compared with phenomenological determinations. Finally, various predictions of prompt quarkonium production at LEP are compared.
The Short But Prominent Life of Quarkonia at CLEO
Authors: Wolf Andreas H.
Published: October 2002

This talk reports two analyses using data from the CLEO1 detector located at the CESR e+e- storage ring, Cornell University. Running mainly at CMS energies around the ϒ(4S) resonance, CLEO supplies us with a large date set of B mesons. But this talk will focus on data taken on the ϒ(1S) resonance to measure the direct photon spectrum from its decay, and a nearly complete analysis searching for direct charmonium production in e+e- reactions and its properties.
QUANTUM TREATMENT OF TIME DEPENDENT COUPLED OSCILLATORS
Authors: ABDALLA M. SEBAWE
Published: October 2002

In this paper we consider the most quadratic time dependent Hamiltonian. An exact solution of the wave function in both the Schrödinger picture and coherent states representation is given. Linear and quadratic invariants are discussed. The eigenvalues and the corresponding eigenfunctions are obtained. The expectation values for the energy are also given.
Ce 4f-LIGAND DEHYBRIDIZATION IN CeT2X2-BASED KONDO LATTICE/HEAVY FERMION SYSTEMS
Authors: LIANG G. , YAO Q.
Published: October 2002

The lattice parameters of two CeT2X2 ( T =3d transition elements and X=Si and Ge) based Kondo lattice systems, the CeNi2-xCux Si2 and Ce(NiSi)2-x (CuGe)x, have been studied. The analysis of the Ce-ligand distances indicates that the variation of the a-parameter dominantly affects Ce 4f-X ligandn orbital hybridization whereas the variation of c-parameter dominantly affects Ce 4f-T ligand orbital hybridization. The average Ce-ligand distance varies linearly with x across the whole series in spite of the abnormal increase of the c-parameter in the region 1.6 ≤ x ≤ 2.0. Thus, our analysis shows that the average Ce 4f-ligand orbital hybridization decreases uniformly with x across the entire range of x for the CeNi2-xCuxSi 2 and Ce(NiSi)2-x(CuGe)x series. The means that the Ce 4f-ligand orbital dehybridization may not be a key factor to the formation of the heavy-fermion ground state in CeCu2Si2.
EFFECTS OF ELECTRIC FIELD ON THE ELECTRONIC STRUCTURE OF QUANTUM DOTS
Authors: WANG LI-MIN , LUO YING , MA BEN-KUN
Published: October 2002

Within the framwork of the effective mass approximation, the electronic structures of quantum dots in the presence of electric field are investigated by the finite element method. Numerical calculation results show that, with finite confining potential, the highest electronic bound state in the quantum dots gradually changes into a quasi-bound state as the electric field strength increases. For the quantum-dot molecules, the valence bonds between quantum dots alternates between the covalent bonds and ionic bonds with increasing electric field strength. The oscillator strength of intraband transition reflects the effect of the electric field on the valence bond property in quantum-dot molecules.
THEORY OF TURBULENCE: ANOMALOUS THERMAL FLUX SPECTRUM
Authors: DEKKER H.
Published: October 2002

A recent theory of fully-developed 3D hydrodynamic turbulence, involving dynamical response functions for turbulent thermal shear flow, yields analytical results for the anomalous Kolmogorov spectrum of streamwise heat flux.
SELF-ATTRACTING WALK ON NON-UNIFORM SUBSTRATES
Authors: TAN ZHI-JIE , ZOU XIAN-WU , ZHANG WEI , HUANG SHENG-YOU , JIN ZHUN-ZHI
Published: October 2002

Self-attracting walk (SATW) on non-uniform substrates has been investigated by Monte Carlo simulations. The non-uniform substrates are described by Leath percolation clusters with occupied probability p. p stands for the degree of non-uniformity, and takes on values in the range pc≲p ≤1 where pc is the threshold of percolation. For the case of strong attractive interaction u, p has little influence on the walk which is dominated by attractive interactions. Furthermore, in the case of small scales, the exponent ν of the mean end-to-end distance  versus time t is given by ν≃1/(ds+1), while the exponent k of visited sites versus t is given by k≃ds/(ds+1), where ds are the fractal dimensions of the substrates. For u ≃ 0, the walk reduces to the random walk on percolations with p in pc≲p≤1. Also, ν and k decrease sensitively with the reduction of p. It is found, the blocked sites in the substrates (i.e. defects) have much greater influence on the walk driven by thermal flunctuation than that dominated by the attractive interaction.
THERMALLY STIMULATED DEPOLARIZATION CURRENTS AND OPTICAL TRANSMISSION STUDIES ON A 3,4-DICYANOTHIOPHENE-BASED BENT-ROD LIQUID CRYSTAL
Authors: ROSU CONSTANTIN , MANAILA-MAXIMEAN DOINA , PARASKOS ALEXANDER J.
Published: October 2002

We study the phase transitions on LC 3,4-Dicyano-2,5-bis[4-(octyloxy)phenylethynyl]-thiophene by the thermally stimulated depolarization currents method and by differential scanning calorimetry. Analyzing the experimental data, information regarding the conduction mechanisms for each mesophase are obtained. The results are consistent with the existence of a space charge polarization where the trapped charges are characterized by a slow retrapping probability. We measure the value of the activation energy, specific to the conduction process. We analyze the influence of the polarizing field on the optical transmission measured simultaneously with the thermally stimulated depolarization currents.
THE NONZERO MINIMUM OF THE DIFFUSION PARAMETER AND THE UNCERTAINTY PRINCIPLE FOR A BROWNIAN PARTICLE
Authors: MAMONTOV E. , WILLANDER M.
Published: October 2002

The limits of applicability of many classical (non-quantum-mechanical) theories are not sharp. These theories are sometimes applied to the problems which are, in their nature, not very well suited for that. Two of the most widely used classical approaches are the theory of diffusion stochastic process and Itô's stochastic differential equations. It includes the Brownian-motion treatment as the basic particular case. The present work shows that, for quantum-mechanical reasons, the diffusion parameter of a Brownian particle cannot be arbitrarily small since it has a nonzero minimum value. This fact leads to the version of Heisenberg's uncertainty principle for a Brownian particle which is obtained in the precise mathematical form of a limit inequality. These quantitative results can help to properly apply the theories associated with Brownian-particle modelling. The consideration also discusses a series of works of other authors.
ADAPTIVE SIMULATED ANNEALING FOR CT IMAGE CLASSIFICATION
Authors: ALBRECHT A. A. , LOOMES M. , STEINHÖFEL K. , TAUPITZ M.
Published: October 2002

We present a pattern classification method that combines the classical Perceptron algorithm with simulated annealing. For a sample set S of n-dimensional patterns labeled as positive and negative, our algorithm computes threshold circuits of small depth where the linear threshold functions of the first layer are calculated by simulated annealing with the logarithmic cooling schedule c(k) = Γ(k)/ ln (k + 2). The parameter Γ depends on the sample set and changes in time, and the neighborhood relation is determined by the Perceptron algorithm. We apply the approach to the recognition of focal liver tumours. From 400 positive (focal liver tumour) and 400 negative (normal liver tissue) examples a depth-six threshold circuit is calculated. The examples are of size n = 14161 = 119 × 119 and they are presented in the DICOM format. On test sets of 100 + 100 examples (disjoint from the learning set) we obtain a correct classification of more than 98%.
ORDER STATISTIC FILTER (OSF): A NOVEL APPROACH TO DOCUMENT ANALYSIS
Authors: MA HONG , ZHOU JIE , MA LI , TANG YUAN Y.
Published: October 2002

Page segmentation is one of the important and basic research subjects of document analysis. There are two major kinds of page segmentation methods, i.e. hierarchical and no-hierarchical ones. Most traditional techniques such as top–down and bottom–up approaches belong to the hierarchical method. Though these two approaches have been used till now, they are not effective for processing documents with high geometric complexity and the process of splitting document needs iterative operations which is time consuming. A non-hierarchical method called the modified fractal signature (MFS) was presented in recent years. It can overcome the above weaknesses, however the MFS needs to calculate modified fractal signature which makes the theory very complex. In this thesis, we present a new page segmentation approach: Median Order Statistic Filter (MedOSF) — Maximum Order Statistic Filter (MaxOSF) approach which is more direct and much simpler. We use the MedOSF to remove the salt–pepper noise of the document and use the MaxOSF to do the page segmentation. In practice, they not only can adaptively process the documents with high geometrical complexity, but also save a lot of computing time.
CONTENT-BASED COLOR TRADEMARK RETRIEVAL SYSTEM USING HIT STATISTIC
Authors: WANG CHUAN-CHENG , CHEN LING-HWEI
Published: October 2002

This paper proposes a content-based color trademark retrieval system. First, the edges of each color trademark are detected. Then, the smallest circle that covers the trademark is derived. Based on the smallest circle and edges, the feature called hit statistic on a dartboard of the color trademark is extracted. Using this feature, this paper constructs an efficient and simple color trademark retrieval system, which is robust to rotation, translation, scaling and some geometric distortions. Some experiments are conducted to compare the proposed system with the existing one using Zernike moment, and the results show that the proposed system is superior to that using Zernike moment.
BINDING ALGORITHM FOR POWER OPTIMIZATION BASED ON NETWORK FLOW METHOD
Authors: CHOI YOONSEO , KIM TAEWHAN
Published: October 2002

We propose an efficient binding algorithm for power optimization in behavioral synthesis. In prior work, it has been shown that several binding problems for low-power can be formulated as multi-commodity flow problems (due to an iterative execution of data flow graph) and be solved optimally. However, since the multi-commodity flow problem is NP-hard, the application is limited to a class of small sized problems. To overcome the limitation, we address the problem of how we can effectively make use of the property of efficient flow computations in a network so that it is extensively applicable to practical designs while producing close-to-optimal results. To this end, we propose a two-step procedure, which (1) determines a feasible binding solution by partially utilizing the computation steps for finding a maximum flow of minimum cost in a network and then (2) refines it iteratively. Experiments with a set of benchmark examples show that the proposed algorithm saves the run time significantly while maintaining close-to-optimal bindings in most practical designs.
A NEURAL BASED HUMAN FACE RECOGNITION SYSTEM USING AN EFFICIENT FEATURE EXTRACTION METHOD WITH PSEUDO ZERNIKE MOMENT
Authors: HADDADNIA JAVAD , FAEZ KARIM , AHMADI MAJID
Published: October 2002

This paper introduces an efficient method for the recognition of human faces in 2D digital images using a feature extraction technique that combines the global and local information in frontal view of facial images. The proposed feature extraction includes human face localization derived from the shape information. Efficient parameters are defined to eliminate irrelevant data while Pseudo Zernike Moments (PZM) with a new moment orders selection method is introduced as face features. The proposed method while yields better recognition rate, also reduces the classifier complexity. This paper also examines application of various feature domains as face features using the face localization method. These include Principle Component Analysis (PCA) and Discrete Cosine Transform (DCT). The Radial Basis Function (RBF) neural network has been used as the classifier and we have shown that the proposed feature extraction method requires an RBF neural network classifier with a simpler structure and faster training phase that is less sensitive to select training and testing images. Simulation results on the Olivetti Research Laboratory (ORL) database and comparison with other techniques indicate the effectiveness of the proposed method.
REAL-TIME ANTICIPATION OF CHAOTIC STATES OF AN ELECTRONIC CIRCUIT
Authors: VOSS HENNING U.
Published: October 2002

This Letter presents an experimental realization of a recently proposed method to anticipate future states of nonlinear time-delayed feedback systems. The electronic circuit allows for a real-time anticipation of even strongly irregular signals. It is found that synchronization of the driven circuit with chaotic future states of the driving circuit is insensitive to signal and system perturbations.
DYNAMICS OF PHASE-LOCKED LOOP WITH FM INPUT AND LOW MODULATING FREQUENCY
Authors: VASYLENKO ANNA , FEELY ORLA
Published: October 2002

Phase-locked loops are important engineering systems whose dynamics are incompletely understood. In this paper we investigate the dynamics of a first-order phase-locked loop with a frequency-modulated input signal of low modulating frequency. The system displays interesting bifurcations not observed at higher modulating frequencies and exhibits a range of behavior, including chaos, quasiperiodic motion and strange nonchaotic attractors.
A SOFTWARE TEST AND EVALUATION ENVIRONMENT BASED ON LONGITUDINAL DATABASE
Authors: OHARA S. , TSUNODA F. , MAEZAWA H. , ONOMA A. K. , HUI M. , WANG T. , SHEU P. C.-Y , PAUL RAYMOND
Published: October 2002

To assure the quality of software by running test cases and evaluating the results is one of the difficult parts of the entire software development project. The difficulty usually comes from the lack of appropriate supporting tools and the complexity of the software. In the past ad hoc supporting tools were made for each project and test results were usually not used across projects. This conventional way of test and evaluation (T&E) is time consuming, and the most important decision "When is this software ready to ship?" is left to the engineers depending on their experiences. Our objective is to build a knowledge-based T&E environment such that tests cases, test results, object snapshots and other information are accumulated in a database. These longitudinal data can be automatically tracked and analyzed to provide decision support information. As a result, test results can be reviewed repeatedly and software quality can be assured by analyzing these data from various perspectives.
A FEATURE-ORIENTED COPYRIGHT OWNER PROVING TECHNIQUE FOR STILL IMAGES
Authors: CHANG CHIN-CHEN , HWANG KUO-FENG , HWANG MIN-SHIANG
Published: October 2002

This paper presents a copyright owner detection technique for images and graphics. A digital time-stamped signature for this copyright identification technique is also introduced in this work. The secret key, used to compute the watermark, is generated from the extracted features of the host images in the proposed scheme. The proposed algorithm enables the successful revealing of watermarks under several attacks, such as filtering, lossy compression, cropping, rotating, and so on. In particular, our method is not only suitable for ordinary natural images, but can also be applied to cartoon graphics. Most importantly, the proposed scheme can be applied to the media in which distortion is not allowable, such as medical images, source code of programs, and so on.
THE STRUCTURE OF COMMUTATIVE RESIDUATED LATTICES
Authors: HART JAMES B. , RAFTER LORI , TSINAKIS CONSTANTINE
Published: October 2002

A commutative residuated lattice, is an ordered algebraic structure [Formula: see text], where (L, ·, e) is a commutative monoid, (L, ∧, ∨) is a lattice, and the operation → satisfies the equivalences [Formula: see text] for a, b, c ∊ L. The class of all commutative residuated lattices, denoted by [Formula: see text], is a finitely based variety of algebras. Historically speaking, our study draws primary inspiration from the work of M. Ward and R. P. Dilworth appearing in a series of important papers [9, 10, 19–22]. In the ensuing decades special examples of commutative, residuated lattices have received considerable attention, but we believe that this is the first time that a comprehensive theory on the structure of residuated lattices has been presented from the viewpoint of universal algebra. In particular, we show that [Formula: see text] is an "ideal variety" in the sense that its congruences correspond to order-convex subalgebras. As a consequence of the general theory, we present an equational basis for the subvariety [Formula: see text] generated by all commutative, residuated chains. We conclude the paper by proving that the congruence lattice of each member of [Formula: see text] is an algebraic, distributive lattice whose meet-prime elements form a root-system (dual tree). This result, together with the main results in [12, 18], will be used in a future publication to analyze the structure of finite members of [Formula: see text]. A comprehensive study of, not necessarily commutative, residuated lattices is presented in [4].
THE 2-GENERATOR RESTRICTED BURNSIDE GROUP OF EXPONENT 7
Authors: O'BRIEN E. A. , VAUGHAN-LEE MICHAEL
Published: October 2002

We report on our construction of a power-commutator presentation for R(2,7), the largest finite 2-generator group of exponent 7. Our calculations show that R(2,7) has order 720416, nilpotency class 28, and derived length 5. The calculations also imply that the associated Lie ring of R(2,7) satisfies relations which are not consequences of the multilinear identities which hold in the associated Lie rings of groups of exponent 7.
A CLASS OF COLLISIONS OF PLANE IMPULSIVE LIGHT-LIKE SIGNALS IN GENERAL RELATIVITY
Authors: BARRABÈS C. , HOGAN P. A.
Published: October 2002

We present a systematic study of collisions of homogeneous, plane- fronted, impulsive light-like signals which do not interact after head-on collision. For the head-on collision of two such signals, six real parameters are involved, three from each of the incoming signals. We find two necessary conditions to be satisfied by these six parameters for the signals to be noninteracting after collision. We then solve the collision problem in the general case when these necessary conditions hold. After collision the two signals focus each other at Weyl curvature singularities on each others signal front. Our family of solutions contains some known collision solutions as special cases.
PLANE-SYMMETRIC INHOMOGENEOUS VISCOUS FLUID COSMOLOGICAL MODELS WITH ELECTROMAGNETIC FIELD
Authors: PRADHAN ANIRUDH , YADAV V. KUMAR , SASTE N. N.
Published: October 2002

We consider a magnetic cylindrically symmetric universe with a plane-symmetric inhomogeneous viscous fluid cosmological model with electromagnetic field. The viscosity coefficient of bulk viscous fluid is assumed to be a power function of mass density. To get a determinate solution, we assume the free gravitational field to be Petrov type-II non-degenerate. Without assuming any ad hoc law, we obtain a cosmological constant as a decreasing function of time. The behaviour of the electromagnetic field tensor together with some physical aspects of the model are also discussed.
METABOLIC NETWORKS FROM (ℳ, ℛ) SYSTEMS AND AUTOPOIESIS PERSPECTIVE
Authors: ZARETZKY ALBA N. , LETELIER JUAN C.
Published: October 2002

This paper is the first one of a series devoted to the analysis of metabolic networks. Its aim is to establish the theoretical framework for this analysis.

Two different lines of research are considered: the one about metabolism-repair systems ((ℳ, ℛ)), introduced by Robert Rosen as an abstract representation of cell metabolic activity, and the concept of autopoiesis developed by Humberto Maturana and Francisco Varela.

Both concepts have been recently connected by Letelier et al., determining that the set of autopoietic systems is a subset of the set of general abstract (ℳ, ℛ) systems. In fact, every specific (ℳ, ℛ) system is an autopoietic one, being the boundary, which specifies each system as a unity, the main element of autopoietic systems which is not formalized in Rosen's representation.

This paper introduces the definition of boundary — a physical boundary and a functional one — for (ℳ, ℛ) systems in the context of a representation using category theory.

The concept of complete (ℳ, ℛ) system is also introduced by means of a process of completion in categories which is functorial, natural and universal.
A DISCRETE SLUG POPULATION MODEL DETERMINED BY EGG PRODUCTION
Authors: SCHLEY DAVID , BEES MARTIN A.
Published: October 2002

Slugs are significant pests in agriculture (as well as a nuisance to gardeners), and it is therefore important to understand their population dynamics for the construction of efficient and effective control measures. Differential equation models of slug populations require the inclusion of large (variable) temporal delays, and strong seasonal forcing results in a non-autonomous system. This renders such models open to only a limited amount of rigorous analysis. In this paper, we derive a novel batch model based purely upon the quantity of eggs produced at different times of the year. This model is open to considerable reduction; from the resulting two variable discrete-time system it is possible to reconstruct the dynamics of the full population across the year and give conditions for extinction or global stability and persistence. Furthermore, the steady state temporal population distribution displays qualitatively different behavior with only small changes in the survival probability of slugs. The model demonstrates how small variations in the favorability of different years may result in widely different slug population fluctuations between consecutive years, and is in good agreement with field data.
ANALYSIS OF A CELL-CYCLE SPECIFIC MODEL FOR CANCER CHEMOTHERAPY
Authors: LEDZEWICZ URSZULA , SCHÄTTLER HEINZ
Published: October 2002

A class of mathematical models for cancer chemotherapy which has been described in the literature takes the form of an optimal control problem with dynamics given by a bilinear system. In this paper we analyze a three-dimensional model in which the cell-cycle is broken into three compartments. The cytostatic agent used as control to kill the cancer cells is active in a compartment which combines the second growth phase and mitosis where cell-division occurs. A blocking agent is used as a second control to slow down the transit of cells during synthesis, but does not kill cells. The cumulative effect of the killing agent is used to model the negative effect of the treatment on healthy cells. It is shown that singular controls are not optimal. This eliminates treatments where during some time only a portion of the full drug dose is administered. Consequently only treatments which alternate between a full and no dose, i.e., so-called bang-bang controls, canbe optimal for this model. Both necessary and sufficient conditions for optimality of treatment schedules of this type are given.
WEAK CONSISTENCY AND QUASI-LINEAR MEANS IMPLY THE ACTUAL RANKING
Authors: BASILE LUCIANO , D'APUZZO LIVIA
Published: October 2002

It is known that in the Analytic Hierarchy Process (A.H.P.) a scale of relative importance for alternatives is derived from a pairwise comparisons matrix A = (aij). Priority vectors are basically provided by the following methods: the right eigenvector method, the geometric mean method and the arithmetic mean method. Antipriority vectors can also be considered; they are built by both the left eigenvector method and mean procedures applied to the columns of A. When the matrix A is inconsistent, priority and antipriority vectors do not indicate necessarily the same ranking. We deal with the problem of the reliability of quantitative rankings and we use quasi-linear means for providing a more general approach to get priority and antipriority vectors.
USING A NOTION OF ACCEPTABLE IN UNCERTAIN ORDINAL DECISION MAKING
Authors: YAGER RONALD R.
Published: October 2002

We focus on the problem of constructing decision functions to aid in the valuation of alteratives in uncertain decision making. We discuss different types of scales available for representing the payoffs associated with the alternatives. Here we consider the case in which our basic scale is an ordinal case. Here however we augment this ordinal scale by allowing an additional notion. We indicate one special element on the scale which we call the denoted element. We name such a scale a Denoted Ordinal Scale (DOS). We point out that a DOS allows a binary partitioning of the basic ordinal scale which can be associated with differing semantics and used for various purposes. Here we focus on a binary partitioning and use a semantics which provides a classification of payoffs as to whether they are acceptable or not. This allows us to have information such as A is preferred to B but both are acceptable. We show how a DOS with this semantics can be used to construct sophisticated decision functions.
HYBRID FUZZY POLYNOMIAL NEURAL NETWORKS
Authors: OH SUNG-KWUN , KIM DONG-WON , PEDRYCZ WITOLD
Published: October 2002

We propose a hybrid architecture based on a combination of fuzzy systems and polynomial neural networks. The resulting Hybrid Fuzzy Polynomial Neural Networks (HFPNN) dwells on the ideas of fuzzy rule-based computing and polynomial neural networks. The structure of the network comprises of fuzzy polynomial neurons (FPNs) forming the nodes of the first (input) layer of the HFPNN and polynomial neurons (PNs) that are located in the consecutive layers of the network. In the FPN (that forms a fuzzy inference system), the generic rules assume the form "if A then y = P(x) " where A is fuzzy relation in the condition space while P(x) is a polynomial standing in the conclusion part of the rule. The conclusion part of the rules, especially the regression polynomial uses several types of high-order polynomials such as constant, linear, quadratic, and modified quadratic. As the premise part of the rules, both triangular and Gaussian-like membership functions are considered. Each PN of the network realizes a polynomial type of partial description (PD) of the mapping between input and out variables. HFPNN is a flexible neural architecture whose structure is based on the Group Method of Data Handling (GMDH) and developed through learning. In particular, the number of layers of the PNN is not fixed in advance but is generated in a dynamic way. The experimental part of the study involves two representative numerical examples such as chaotic time series and Box-Jenkins gas furnace data.
ANGLE-SCANNED PHOTOEMISSION ON YbHx: RELEVANCE FOR SWITCHABLE MIRRORS
Authors: HAYOZ J. , KOITZSCH C. , POPOVIĆ D. , BOVET M. , NAUMOVIĆ D. , AEBI P.
Published: October 2002

Yttrium, lantanum and rare earth elements can be loaded with hydrogen inducing a metal–insulator transition and giving rise to optical switching from reflecting to transparent. We present angle-scanned photoemission experiments characterizing thin YbH x films grown on W(110) at room temperature. Hydrogen loading is performed in an ultrahigh-vacuum-compatible high pressure (1 bar) reaction cell. Via full-hemispherical X-ray photoelectron diffraction and low energy electron diffraction, it is demonstrated that these films grow well-ordered and single-crystalline. Ultraviolet photoemission reveals a gap for the dihydride phase confirming a transition from reflecting to transparent as seen by visual inspection. Ion implantation through additional H+ sputtering allows one to increase the hydrogen content to x ≈ 2.4.
SOFT X-RAY MICROSCOPY OF SOFT MATTER — HARD INFORMATION FROM TWO SOFTS
Authors: HITCHCOCK A. P. , MORIN C. , TYLISZCZAK T. , KOPRINAROV I. N. , IKEURA-SEKIGUCHI H. , LAWRENCE J. R. , LEPPARD G. G.
Published: October 2002

Scanning transmission X-ray microscopy (STXM) and X-ray photoelectron emission microscopy (X-PEEM) provide quantitative chemical analysis at a spatial resolution well below 100 nm. Soft X-ray absorption or near edge X-ray absorption (NEXAFS) contrast provides sensitive differentiation of species which have similar elemental composition but are chemically distinct. Due to the ability of soft X-rays at wavelengths below the O K-edge to penetrate water, and on account of lower radiation damage, soft X-ray microscopy is an ideal tool for providing quantitative information about soft matter in the context of biological, polymer and environmental studies. Examples are given from recent studies of: phase segregation in polyurethanes and polymer blends, protein adsorption on polymers relating to biomaterial optimization, and metal mapping in biofilms. These examples show that it is indeed possible to get quantitative (hard) information by combining soft X-rays and soft materials.
LACK OF ATOMIC CHARGE LOCALIZATION IN TRANSITION METAL MIXED VALENCE OXIDES
Authors: GARCÍA J. , BLASCO J. , SÁNCHEZ M. C. , PROIETTI M. G. , SUBÍAS G.
Published: October 2002

We review our recent studies on the occurrence of atomic charge localization in magnetite and half-doped manganites. X-ray resonant scattering experiments at the iron K-edge of magnetite and X-ray absorption spectroscopy at the Mn K-edge of Ca-doped manganites show the lack of charge localization on the transition metal atom, either temporal or spatial. The evolution of the intensity of (002) and (006) forbidden reflections in magnetite across the Verwey transition, as a function of the incoming X-ray beam energy, the azimuthal angle and the polarization of the scattering process, indicates that the atomic anomalous scattering factors for the octahedral iron ions are identical to each other, i.e. all of them show an identical electronic state. High resolution XANES spectra of RE 1-x Ca x MnO 3 series cannot be reproduced by a linear combination of REMnO3 and CaMnO 3 spectra. Accordingly, the electronic state of the Mn atom in these intermediate compounds cannot be described as a bimodal distribution of Mn 3+ and Mn 4+ pure ionic states. The claimed experimental evidence of charge ordering in Mn 3+/ Mn 4+=1 manganites proposed from X-ray resonant scattering experiments has also been critically re-examined. We show that although these experiments prove the existence of two kinds of Mn atoms, they cannot be identified as Mn 3+ and Mn 4+ ions. Moreover, the so-called charge-ordering (CO) and orbital-ordering (OO) resonant scattering reflections are naturally explained due to the presence of local distortions without including any ordering of the Mn d-orbitals.