bluuebunny/crossref_metadata_2025 huggingface dataset:
Supersymmetric Lepton Flavor Violation, the Muon Anomalous Magnetic Moment, and e- e- Colliders
Authors: Kribs Graham D.
Published: August 2003

I explain the theoretical connection between lepton flavor violation and muon g - 2 in supersymmetry1. Given any central value deviation of muon g - 2 from the standard model that is assumed to be due to weak scale supersymmetry, I show that stringent bounds on lepton flavor violating scalar masses can be extracted. These bounds are essentially independent of supersymmetric parameter space. I then briefly compare this indirect handle on supersymmetric lepton flavor violation with direct observation at a future lepton collider operating in the e- e- mode. This is a summary of a talk given at e- e-01: 4th International Workshop on Electron-Electron Interactions at TeV Energies.
Universal Extra Dimensions at the e- e- Colliders
Authors: Cheng Hsin-Chia
Published: August 2003

Universal Extra Dimensions (UEDs) with compactification radius near the TeV scale provide interesting phenomenology at future colliders. The collider signals of the first Kaluza-Klein (KK) level are very similar to those of a supersymmetric model with a nearly degenerate superpartner spectrum. The heavier first level KK states cascade decay to the lightest KK particles (LKP), which is neutral and stable because of KK-parity. The signatures involve missing energy and relatively soft jets and leptons which can be difficult for detection. The KK electron signal in e-e- collisions is free from the problematic two photon background therefore provides a unique opportunity for a detailed studies of the KK electrons in the Universal Extra Dimension scenario.
Deeply Virtual Compton Scattering in e- e- and e- γ Collisions
Authors: Hwang Dae Sung
Published: August 2003

The matrix elements of the local operators such as electromagnetic current, energy momentum tensor, angular momentum, and generalized parton distributions have exact representations in terms of light-cone Fock state wavefunctions of bound states such as hadrons. We present formulae which express the form factors of the local operators in terms of the light-cone wavefunctions. We propose the measurement of the generalized parton distributions of the high energy real photon by the deeply virtual Compton scattering experiments.
Signals for Noncommutative QED at Future e+ e- Colliders
Authors: Rizzo Thomas G.
Published: August 2003

The signatures for noncommutative QED at e+ e- colliders with center of mass energies in the range of 0.5-5 TeV are examined. For integrated luminosities of 0.5-1 ab -1 or more, sensitivities to the associated mass scales greater than [Formula: see text] are possible.
Radiative Corrections and Polarization Effects to Møller Scattering
Authors: Mossolov V. A. , Shumeiko N. M. , Suarez J. G.
Published: August 2003

Polarization effects including radiative corrections have been considered. Exact lowest-order covariant calculation of QED RC has been carried out and detailed numerical analysis is given. The hard photon contribution is calculated analytically. Exponentation procedure is used to consider multi-soft-photon contribution. Numerical analysis is perfomed for beam polarization measurements at Møller polarimeter.
Studying Standard Model-Like Higgs Bosons in Two-Photon Collisions at a Linear Collider
Authors: Asner David
Published: August 2003

We examine the potential for detecting and studying a SM-like Higgs boson in two-photon collisions at a future linear collider. Our study incorporates realistic two-photon spectra based on the most probable available laser technology.
Luminosity Expectations for Electron-Electron Collisions at TESLA
Authors: Schreiber S.
Published: August 2003

Electron-electron collisions at the future TESLA linear collider have been studied. Achievable luminosity and luminosity spectra for parameters close to the standard TESLA design are given.
The NLC IR and e+ e-/e- e- Compatibility Issues
Authors: Markiewicz T. W.
Published: August 2003

This paper collects and summarizes information presented at previous e - e - workshops. First, the various options for reconfiguring magnets and power sources to convert the NLC to e - e - operation are discussed. Second, the expected backgrounds from pair creation at the interaction point are presented. Lastly, beam loss in the extraction line is discussed.
The Plasma Lens as an e-e- Luminosity Enhancer: SLAC Experimental Results
Authors: Bolton Paul R.
Published: August 2003

The use of gaseous plasmas to strongly focus high density, high energy electron and positron beams has been experimentally demonstrated. Focusing plasmas have been beam-induced. In addition, interesting aspects of laser-induced preionization of the target gas have been observed. Potential applications to luminosity enhancement for linear colliders warrant further development of these techniques with machine parameters in mind.
Some Thoughts on e- e- Collisions in CLIC
Authors: Schulte D.
Published: August 2003

Linear e + e - colliders have the potential to also be used to realise e - e - collisions. Some preliminary thoughts about the realisation of this at CLIC are presented. Luminosity and some background estimates are also given.
Plasma Lens Backgrounds at a Future Linear Collider
Authors: Weidemann Achim W. , Chen P. , Ng C.-K.
Published: August 2003

A 'plasma lens' might be used to enhance the luminosity of future linear colliders. However, its utility for this purpose depends largely on the potential backgrounds that may be induced by the insertion of such a device in the interaction region of the detector. In this note we identify different sources of such backgrounds, calculate their event rates from the elementary interaction processes, and evaluate their effects on the major parts of a hypothetical Next Linear Collider (NLC) detector. For plasma lens parameters which give a factor of seven enhancement of the luminosity, and using the NLC design for beam parameters as a reference, we find that the background yields are fairly high, and require further study and improvements in detector technology to avoid their impact.
Physics Opportunities at a Photon–Photon Collider
Authors: Brodsky Stanley J.
Published: August 2003

The advent of back-scattered laser beams for e±e-colliders will allow detailed studies of a large array of high energy γγ and γe collision processes with polarized beams. These include tests of electroweak theory in photon-photon annihilation such as γγ → W+W-, γγ → Higgs bosons, and higher-order loop processes, such as γγ → γγ, Zγ, H0Z0and ZZ. Methods for measuring the anomalous magnetic and quadrupole moments of the W and Z gauge bosons to high precision in polarized electron-photon and photon-photon collisions are discussed. Since each photon can be resolved into a W+W-pair, high energy photon-photon collisions can also provide a remarkably background-free laboratory for studying WW collisions and annihilation. I also review high energy γγ and eγ tests of quantum chromodynamics, including the production of two gluon jets in photon-photon collisions, deeply virtual Compton scattering on a photon target, and leading-twist single-spin asymmetries for a photon polarized normal to a production plane. Exclusive hadron production processes in photon-photon collisions provide important tests of QCD at the amplitude level, particularly as measures of hadron distribution amplitudes which are also important for the analysis of exclusive semi-leptonic and two-body hadronic B-decays.
Prospect for Discovering H0, A0 in Two-Photon Collisions at a Linear Collider
Authors: Asner David
Published: August 2003

We examine the potential for detecting and studying Higgs bosons in two-photon collisions at a future linear collider. Our study incorporates realistic two-photon spectra based on the most probable available laser technology. We study the cases of a) the heavy MSSM Higgs bosons and b) a Higgs boson with no WW/ZZ couplings from a general two Higgs doublet model.
A Photon Collider Testbed at the SLC
Authors: Gronberg Jeff
Published: August 2003

The idea of producing a high-energy photon-photon collider1, based on Compton backscattering of laser photons from an electron beam, was proposed in the early 1980's. In this idea, a linear e+ e- collider must be upgraded with high power lasers and an interaction region including optics to focus the laser pulses onto the electron beam. Recently, a strawman design for such an interaction region has been produced. Given the existence of the mothballed Stanford Linear Collider it becomes reasonable to propose a photon collider test bed, which would allow that design to be tested in actual operational conditions.
Time-Splitting Schemes and Measure Source Terms for a Quasilinear Relaxing System
Authors: Gosse Laurent
Published: August 2003

Several singular limits are investigated in the context of a 2 × 2 system arising for instance in the modeling of chromatographic processes. In particular, we focus on the case where the relaxation term and a L2 projection operator are concentrated on a discrete lattice by means of Dirac measures. This formulation allows one to study more easily some time-splitting numerical schemes.
Convergence of a Contact-Neumann Iteration for the Solution of Two-Body Contact Problems
Authors: Eck C. , Wohlmuth B.
Published: August 2003

We study an iteration for the solution of two-body contact problems without friction based on one-sided contact problems for one body and Neumann problems for the other one. The convergence of this iteration is proved in the continuous setting by reformulating it as a fixed point iteration for a contractive operator. In addition, the application of the method with mortar finite elements is discussed, and the convergence of the corresponding discrete iteration is verified.
An Existence Result for a Stationary Vlasov–Poisson Model with Source Term
Authors: Ambroso Annalisa , Fleury Xavier , Raviart Pierre-Arnaud
Published: August 2003

In the low energy part of an ion accelerator, the ion beam reaches the first accelerating device through a drift tube where a residual neutral gas is present. A process of ionization takes place and secondary electrons and ions are created. We analyze the coupling between these secondary particles, the beam density and the electrical potential.

In a previous article,2 we proved that a stationary Vlasov–Poisson problem with ionization source terms, which, at first sight, seems the natural model for this system, does not admit solutions. To overcome this difficulty, we propose here a heuristic model which consists of modifying the electron source term. In this new frame, we prove that the problem can be solved and we give numerical examples.
On the Well-Posedness of a Coupled One-Dimensional Biological-Physical Model for the Upper Ocean
Authors: Faugeras Blaise
Published: August 2003

This paper introduces a one-dimensional NPZD-model developed to simulate biological activity in a turbulent ocean water column. The model consists of a system of coupled semilinear parabolic equations. An initial-boundary value problem is formulated and the existence of a unique positive weak solution to it is proved. The existence result is derived using a variational formulation, an approximate model and a fixed-point method. It is shown that the qualitative analysis performed still applies if different parametrizations of several biological processes found in the biogeochemical modeling literature are used.
Local Density Approximations for the Energy of a Periodic Coulomb Model
Authors: Bokanowski Olivier , Grebert Benoît , Mauser Norbert J.
Published: August 2003

We deal with local density approximations for the kinetic and exchange energy term, ℰ kin (ρ) and ℰ ex (ρ), of a periodic Coulomb model. We study asymptotic approximations of the energy when the number of particles goes to infinity and for densities close to the constant averaged density. For the kinetic energy, we recover the usual combination of the von-Weizsäcker term and the Thomas–Fermi term. Furthermore, we justify the inclusion of the Dirac term for the exchange energy and the Slater term for the local exchange potential.
A Posteriori Error Estimates for the Finite Element Approximation of Eigenvalue Problems
Authors: Durán Ricardo G. , Padra Claudio , Rodríguez Rodolfo
Published: August 2003

This paper deals with a posteriori error estimators for the linear finite element approximation of second-order elliptic eigenvalue problems in two or three dimensions. First, we give a simple proof of the equivalence, up to higher order terms, between the error and a residual type error estimator. Second, we prove that the volumetric part of the residual is dominated by a constant times the edge or face residuals, again up to higher order terms. This result was not known for eigenvalue problems.
Improvement of Robot Sensor by Integrating Information Using Neural Network
Authors: Takeuchi Hiromi , Terabayashi Yoshifumi , Yamauchi Koichiro , Ishii Naohiro
Published: August 2003

Recently, the improvement of robotics makes us feel the robot to be more familiar to human activities. For example, robot's motion similar to human movement is also developed. However, in order for a robot to play an active part in the medical and welfare field, the sensors of the robot will be important to have effective functions for robot's safety actions. Our approach is applying intelligent processing technology for the sensors by using neural networks. Our purpose is making recognition system with several sensors. We developed a sensory integrating system by the neural network and apply the system to the robotics. This robot can track the target by applying integrated neural system. We extend the robot system to avoid obstacles, which is based on a subsumption architecture.
A Fast Evolutionary Metaheuristic for the Vehicle Routing Problem with Time Windows
Authors: Bräysy Olli , Dullaert Wout
Published: August 2003

This paper presents a new evolutionary metaheuristic for the vehicle routing problem with time windows. Ideas on multi-start local search, ejection chains, simulated annealing and evolutionary computation are combined in a heuristic that is both robust and efficient. The proposed method produces results that are on par with the current best solutions, at a fraction of the computation time needed by previous best approaches. Given the significantly lower time consumption over methods proposed previously in the literature, we consider our approach especially useful in dynamic routing problems, where decisions must be made in real-time.
Application of Fuzzy H∞ Control via T–S Fuzzy Models for Nonlinear Time-Delay Systems
Authors: Hsiao Feng-Hsiag , Chiang Wei-Ling
Published: August 2003

This paper deals with the problem of stability analysis and stabilization via Takagi-Sugeno (T-S) fuzzy models for nonlinear time-delay systems. First, Takagi-Sugeno (T-S) fuzzy models and some stability results are recalled. To design fuzzy controllers, nonlinear time-delay systems are represented by Takagi-Sugeno fuzzy models. The concept of parallel-distributed compensation (PDC) is employed to determine structures of fuzzy controllers from the T-S fuzzy models. LMI-based design problems are defined and employed to find feedback gains of fuzzy controller and common positive definite matrices P satisfying stability a delay-dependent stability criterion derived in terms of Lyapunov direct method. Based on the control scheme and this criterion, a fuzzy controller is then designed via the technique of PDC to stabilize the nonlinear time-delay system and the H∞ control performance is achieved in the mean time. Finally, the proposed controller design method is demonstrated through numerical simulations on the chaotic and resonant systems.
A Metaheuristic for the Pickup and Delivery Problem with Time Windows
Authors: Li Haibing , Lim Andrew
Published: August 2003

In this paper, we propose a metaheuristic to solve the pickup and delivery problem with time windows. Our approach is a tabu-embedded simulated annealing algorithm which restarts a search procedure from the current best solution after several non-improving search iterations. The computational experiments on the six newly-generated different data sets marked our algorithm as the first approach to solve large multiple-vehicle PDPTW problem instances with various distribution properties.
GAPS: A Genetic Programming System
Authors: Zhang Du , Kramer Michael D.
Published: August 2003

One of the major approaches in the field of evolutionary computation is genetic programming. Genetic programming tackles the issue of how to automatically create a computer program for a given problem from some initial problem statement. The goal is accomplished by genetically breeding a population of computer programs in terms of genetic operations. In this paper, we describe a genetic programming system called GAPS. GAPS has the following features: (1) It implements the standard generational algorithm for genetic programming with some refinement on controlling introns growth during evolution process and improved termination criteria. (2) It includes an extensible language tailored to the needs of genetic programming. And (3) It is a complete, standalone system that allows for genetic programming tasks to be carried out without requiring other tools such as compilers. Results with GAPS have been satisfactory.
NEUTRINO ASYMMETRY IN GENERAL RELATIVISTIC ROTATING RADIATIVE STARS
Authors: GARCIA DE ANDRADE L. C.
Published: August 2003

Neutrino asymmetry in general relativistic radiative spacetime exterior to spinning stars is investigating by making use of Newman–Penrose (NP) spin coefficient formalism. It is shown that neutrino current depends on the direction of rotation of the star. The solution is obtained in test field approximation where the neutrinos do not generate gravitational fields.
RADIATING GRAVITATIONAL COLLAPSE WITH SHEAR REVISITED
Authors: CHAN R.
Published: August 2003

A model is proposed for a collapsing radiating star consisting of a fluid with shear motion undergoing radial heat flow with outgoing radiation. The pressure of the star, at the beginning of the collapse, is isotropic but due to the presence of the shear motion of the fluid the pressure becomes more and more anisotropic. The radial and temporal behaviors of the density, the pressure, the total mass, the luminosity, the effective adiabatic index and the Kretschmann scalar are analyzed for a star with 6 M⊙. The final evolution is a star that radiates all its mass during the collapse, and thus, neither forming a black hole, as in the previous model, nor a naked singularity.
TRAPPING PHOTONS BY A LINE SINGULARITY
Authors: ARIK METIN , DELICE OZGUR
Published: August 2003

We present cylindrically symmetric, static solutions of the Einstein field equations around a line singularity such that the energy momentum tensor corresponds to infinitely thin photonic shells. Positivity of the energy density of the thin shell and the line singularity is discussed. It is also shown that thick shells containing mostly radiation are possible in a numerical solution.
COSMOLOGICAL PREDICTIONS FROM THE MISNER BRANE
Authors: GONZÁLEZ-DÍAZ PEDRO F.
Published: August 2003

Within the spirit of five-dimensional gravity in the Randall-Sundrum scenario, in this paper we consider cosmological and gravitational implications induced by forcing the spacetime metric to satisfy a Misner-like symmetry. We first show that in the resulting Misner-brane framework the Friedmann metric for a radiation dominated flat universe and the Schwarzschild or anti-de Sitter black hole metrics are exact solutions on the branes, but the model cannot accommodate any inflationary solution. The horizon and flatness problems can however be solved in Misner-brane cosmology by causal and noncausal communications through the extra dimension between distant regions which are outside the horizon. Based on a semiclassical approximation to the path-integral approach, we have calculated the quantum state of the Misner-brane universe and the quantum perturbations induced on its metric by brane propagation along the fifth direction. We have then considered testable predictions from our model. These include a scale-invariant spectrum of density perturbations whose amplitude can be naturally accommodated to the required value 10-5-10-6, and a power spectrum of CMB anisotropies whose acoustic peaks are at the same sky angles as those predicted by inflationary models, but having much smaller secondary-peak intensities. These predictions seem to be compatible with COBE and recent Boomerang and Maxima measurements.
MIXMASTER CHAOTICITY AS SEMICLASSICAL LIMIT OF THE CANONICAL QUANTUM DYNAMICS
Authors: IMPONENTE GIOVANNI , MONTANI GIOVANNI
Published: August 2003

Within a cosmological framework, we provide a Hamiltonian analysis of the Mixmaster Universe dynamics on the base of a standard Arnowitt–Deser–Misner approach, showing how the chaotic behavior characterizing the evolution of the system near the cosmological singularity can be obtained as the semiclassical limit of the canonical quantization of the model in the same dynamical representation. The relation between this intrinsic chaotic behavior and the indeterministic quantum dynamics is inferred through the coincidence between the microcanonical probability distribution and the semiclassical quantum one.
ENTROPY OF A ROTATING AND ARBITRARILY ACCELERATING BLACK HOLE
Authors: YANG XUEJUN , HAN YIWEN , ZHAO ZHENG
Published: August 2003

The entropy of a rotating and arbitrarily accelerating black hole whose metric changes slowly is calculated using the thin film brick-wall model. We obtain the entropy density at every point of the horizon surface and the total entropy of the black hole. The results show that the entropy of the nonstationary black hole is also proportional to the surface area of the black hole's event horizon as in the cases of stationary black holes.
FLRW UNIVERSES FROM "WAVE-LIKE" COSMOLOGIES IN 5D
Authors: PONCE DE LEON J.
Published: August 2003

We consider the evolution of a 4D-universe embedded in a five-dimensional (bulk) world with a large extra dimension and a cosmological constant. The cosmology in 5D possesses "wave-like" character in the sense that the metric coefficients in the bulk are functions of the extra coordinate and time in a way similar to a pulse or traveling wave propagating along the fifth dimension. This assumption is motivated by some recent work presenting the big-bang as a higher dimensional shock wave. We show that this assumption, together with an equation of state for the effective matter quantities in 4D, allows Einstein's equations to be fully integrated. We then recover the familiar FLRW universes, on the four-dimensional hypersurfaces orthogonal to the extra dimension. Regarding the extra dimension we find that it is growing in size if the universe is speeding up its expansion. We also get an estimate for the relative change of the extra dimension over time. This estimate could have important observational implications, notably for the time variation of rest mass, electric charge and the gravitational "constant". Our results extend previous ones in the literature.
INVESTIGATIONS OF PULSATIONAL PROPERTIES AND EVOLUTION OF PROPAGATION DIAGRAM IN SOME δ SCUTI STAR MODELS
Authors: KIZILOĞLU N. , KIRBIYIK H. , CIVELEK R.
Published: August 2003

An investigation on the subject of evolution of propagation diagrams and obtaining the theoretical frequency spectrum of some δ Scuti star models with masses around 2 M⊙ has been presented. The variations of some eigenfunctions throughout the star, the variation of ω2 with log Te and the distribution of nodes of eigenfunctions of some modes along with the evolution of the star have been plotted and examined. For the models at the ZAMS phase, pure acoustic modes in the outer stellar layers and pure gravity modes in the interiors were calculated. A mixed character of low degree nonradial modes was found in evolved models. These modes behave like p modes in the envelope and like g modes in the interior.
ENTROPIC ISSUES IN CONTEMPORARY COSMOLOGY
Authors: COULE D. H.
Published: August 2003

Penrose1has emphasized how the initial big bang singularity requires a special low entropy state. We address how recent brane cosmological schemes address this problem and whether they offer any apparent resolution. Pushing the start time back to t = -∞, or utilizing maximally symmetric AdS spaces, simply exacerbates or transfers the problem. Since the entropy of de Sitter space is S ≤ 1/Λ, using the present acceleration of the universe as a low energy (Λ ~ 10-120) inflationary stage, as in cyclic ekpyrotic models, produces a gravitational heat death after one cycle. Only higher energy driven inflation, together with a suitable, quantum gravity holography style, restriction on ab initio degrees of freedom, gives a suitable low entropy initial state. We question the suggestion that a high energy inflationary stage could be naturally reentered by Poincaré recurrence within a finite causal region of an accelerating universe.

We further give a heuristic argument that the so-called eternal inflation is not consistent with the second law of thermodynamics within a causal patch.
SPHERICALLY SYMMETRIC SPACE–TIME WITH REGULAR DE SITTER CENTER
Authors: DYMNIKOVA IRINA
Published: August 2003

We formulate the requirements which lead to the existence of a class of globally regular solutions of the minimally coupled GR equations asymptotically de Sitter at the center. The source term for this class, invariant under boosts in the radial direction, is classified as spherically symmetric vacuum with variable density and pressure [Formula: see text] associated with an r-dependent cosmological term [Formula: see text], whose asymptotic at the origin, dictated by the weak energy condition, is the Einstein cosmological term Λgμν, while asymptotic at infinity is de Sitter vacuum with λ < Λ or Minkowski vacuum. For this class of metrics the mass m defined by the standard ADM formula is related to both the de Sitter vacuum trapped at the origin and the breaking of space–time symmetry. In the case of the flat asymptotic, space–time symmetry changes smoothly from the de Sitter group at the center to the Lorentz group at infinity through radial boosts in between. Geometry is asymptotically de Sitter as r → 0 and asymptotically Schwarzschild at large r. In the range of masses m ≥ m crit , the de Sitter–Schwarzschild geometry describes a vacuum nonsingular black hole (ΛBH), and for m < m crit it describes G-lump — a vacuum selfgravitating particle-like structure without horizons. In the case of de Sitter asymptotic at infinity, geometry is asymptotically de Sitter as r → 0 and asymptotically Schwarzschild–de Sitter at large r. Λμν geometry describes, dependently on parameters m and [Formula: see text] and choice of coordinates, a vacuum nonsingular cosmological black hole, self-gravitating particle-like structure at the de Sitter background λgμν, and regular cosmological models with cosmological constant evolving smoothly from Λ to λ.
A GENERALIZED VACUOLE MODEL IN HIGHER DIMENSIONS
Authors: BANERJEE A. , CHATTERJEE S.
Published: August 2003

We extend to higher dimensions a recent work of Bonnor, which generalizes the Einstein–Straus model utilizing the inhomogeneous Tolman–Bondi universe in place of the homogeneous Friedmann one. Following Israel's junction conditions, the criteria of matching between the higher dimensional Schwarzschild-like interior and the Tolman–Bondi-like exterior is obtained. We also give a new exact solution for a five-dimensional TB type of metric and use it to study the dynamical behavior of the vacuole boundary. Furthermore the transformation relations which transform the inhomogeneous TB metric to the homogeneous Friedmann model are explicitly given for any arbitrary dimensions. The frequency shift of radiation coming from the boundary surface is calculated and it is found that, depending on initial conditions both redshift and blue-shift are possible for an expanding vacuole. This is at variance with Bonnor's result where only redshift is possible under similar situation. It is also observed that higher dimensional models are less stable against perturbation than the usual 4D ones.
PERFECT FLUID COSMOLOGICAL MODELS WITH TIME-VARYING CONSTANTS
Authors: BELINCHÓN JOSÉ ANTONIO , CHAKRABARTY INDRAJIT
Published: August 2003

In this paper, we study in detail a perfect fluid cosmological model with time-varying "constants" using dimensional analysis and the symmetry method. We examine the case of variable "constants" in detail without considering the perfect fluid model as a limiting case of a model with a causal bulk viscous fluid as discussed in a recent paper. We obtain some new solutions through the Lie method and show that when matter creation is considered, these solutions are physically relevant.
An Abstract Mandelbrot Set Algorithm for zn + c
Authors: Kern Albert , Frame Michael
Published: August 2003

We present an algorithm, an extension of Lavaurs' algorithm for z2+c, for determining the combinatorial arrangement of the hyperbolic components of the generalized Mandelbrot set for zn+c. Several external rays are plotted to support the algorithm.
Iteration Logistic Map Dynamics in the Polar Coordinates
Authors: Sun Haijian , Liu Lin , Guo Aike
Published: August 2003

The complicated dynamics of logistic maps with four fundamental operations in the polar coordinates are analyzed in this paper. Iterations of single logistic map in polar coordinates exhibit similar characteristics as in the Cartesian coordinates. Iterations of double logistic maps, however, are more interesting in polar coordinates than those in Cartesian coordinates. Under different iterative rules, the dynamics of double logistic maps show some funny artistic patterns. Some of them look like the formation of an embryo, and some even look like Taiji diagram, which is the representative symbol of Taoism in ancient China. It is interesting to see that Taiji, which is believed in Taoism to be the mysterious origination of the world, is an interim phenomenon within the evolution of the systems governed by the law of the logistic equations.
Scaling Behavior of a Self-Affine Fractal Interface in a Tree Line
Authors: Kim Soon-Chul , Yoon Zi-Hong , Kwon Tai-Hyung
Published: August 2003

Scaling behavior of a self-affine fractal interface observed in a tree line is examined. A series of relatively horizontal tree lines are photographed, and each 9 cm × 13 cm color print is scanned and digitized to obtain the interface height h(x) as a function of position x. From these, the interface with w(L) is determined as a function of system size L. It is found that the interface width scales with system size L as w(L)~Lα with α=0.66±0.03. The result is assessed in comparison with other relevant experimental and theoretical results.
Fractal Properties of Generalized Sierpiński Triangles
Authors: Falconer Kenneth J. , Lammering Birger
Published: August 2003

We calculate the box-counting dimension of a self-affine version of the Sierpiński triangle. This is done by investigating the singular values of the affine transformations. We also investigate multifractal features of self-affine measures supported by certain generalized Sierpiński triangles.
Fractal Analysis of Height Distributions of Anisotropic Rough Surfaces
Authors: Blackmore Denis , Zhou Jack G.
Published: August 2003

A general distribution function for the heights of anisotropic engineering surfaces is obtained by extending earlier work on surface profiles. The derivation starts from a functional description of surface heights that involves fractal quantities and is comprehensive enough to include almost all of the mathematical models for surface topography that have appeared in the literature. It is found that the distribution is in the form of a Gaussian function multiplied by a convergent power series, and the terms in the series depend in a fundamental way on the fractal parameters of the surface. This distribution is used to predict the dependence of bearing-area on fractal parameters, and is compared with other approaches to anisotropic surfaces in the literature. Two truncated approximate versions of the distribution function are introduced in order to test the theoretical model against experimentally obtained distributions of engineering surfaces; the results show good agreement between theory and experiment.
Fractal Dimensions in Tunneling Processes and Effects of Environmental Fluctuations
Authors: Kovanis Vassilios , Grigolini Paolo , Kenkre V. M. , Tsironis G. P.
Published: August 2003

We study electron tunneling between two infinte potential square wells connected via an opaque barrier and find that time evolution of the probability of the presence of a Gaussian wave packet, localized initially in one of the wells, shares the fractal behavior of tunneling in a quartic potential, discovered by Dekker (H. Dekker, Phys. Rev.A35, 1825 (1987). However, the fractal dimensions are found to be closer to those of a conventional Weierstrass function than those appropriate to the quasi-Weierstrass behavior of Dekker. It is argued that the usual exponential decay predicted by conventional relaxation processes can be recovered only as an effect of thermal fluctuations.
Country Dependence on Company Size Distributions and a Numerical Model Based on Competition and Cooperation
Authors: Takayasu Hideki , Okuyama Kenji
Published: August 2003

By analyzing international company data we find that company size distributions are not universal but clearly depend on country. In each country, the size distributions for different categories of business are quite similar. In order to understand the country dependence we introduce a numerical model of company size which is based on two effects: stochastic competitive growth by capital exchange, and deterministic protection of small companies by equi-partition of taxed wealth. A power law distribution is realized when the protection effect is negligible. The model is also consistent with the empirical laws for company's growth rates.
Forest Dynamics with Canopy Gap Expansion and Stochastic Ising Model
Authors: Katori Makoto , Kizaki Shinya , Terui Youichi , Kubo Takuya
Published: August 2003

Importance of the influence of neighboring canopy gaps upon new gap creation has been clarified by the ecological study of a neotropical forest on Barro Colorado Island (BCI), Panama. A stochastic lattice model for the forest dynamics with interacting canopy gap expansion was introduced by Kubo et al. We give a theorem showing a condition that this model can be regarded as a stochastic Ising model, and that its stationary state is exactly given by a Gibbs state. Using this theorem, we obtain a Gibbs state which remarkably well approximates the real gap-size distribution in BCI.
Numerical Estimates of the Fractal Dimension of the Spatial Human Bronchial Tree by Two-Dimensional Box-Counting-Method
Authors: Stypa Jörn
Published: August 2003

Photographs of the human bronchial trees were obtained from resin casts. After data editing, the fractal dimension of the contour of the bronchial tree was determined by the 2D box-counting-method (2D-BCM). Mathematical theorems about projections and intersections allow us to determine the fractal dimension of the spatial human bronchial tree.
R/S Analysis Strange Attractors
Authors: de la Fuente I. M. , Martinez L. , Aguirregabiria J. M. , Veguillas J.
Published: August 2003

A method to estimate the persistent behavior from a chaotic time series is proposed. Persistency means that here each value depends to some extent on the previous values and not only on the recent ones. The data were analyzed by means of Hurst's rescaled range method, i.e., R/S analysis (which was introduced by Mandelbrot and Wallis). The relation of the Hurst exponent to the self-affine and self-simialr fractal dimension is discussed.
Allometric Control of Human Gait
Authors: West Bruce J. , Griffin Lori
Published: August 2003

The stride interval in normal human gait is not strictly constant, but fluctuates from step to step in a random manner. These fluctuations have traditionally been assumed to be uncorrelated random errors with normal statistics. Herein we show that, contrary to thes assumption these fluctuations have long-time correlations. Further, these long-time correlations are interpreted in terms of a scaling in the fluctuations indicating an allometric control process. To establish this result we measured the stride interval of a group of five healthy men and women as they walked for 5 to 15 minutes at their usual pace. From these time series we calculate the relative dispersion, the ratio of the standard deviation to the mean, and show by systematically aggregating the data that the correlation in the stride-interval time series is an inverse power law similar to the allometric relations in biology. The inverse power-law relative dispersion shows that the stride-interval time series scales indicating long-time self-similar correlations extending for hundreds of steps, which is to say that the underlying process is a random fractal. Furthermore, the power-law index is related to the fractal dimension of the time series. To determine if walking is a nonlinear process the stride-interval time series were randomly shuffled and the differences in the fractal dimensions of the surrogate time series from those of the original time series were determined to be statistically significant. This difference indicates the importance of the long-time correlations in walking.
The Galaxy Distribution
Authors: McCauley Joseph L.
Published: August 2003

From the standpoint of theoretical physics we can treat Newtonian cosmology as a problem in nonlinear dynamics. The attempt to average the density, in search of a method of making contact between theory and observation, is replaced by the more systematic idea of coarsegraining. I also explain in this context why two previous attempts at the construction of hierarchical models of the universe are not useful for data analysis. The main ideas behind two older competing data analyses purporting to show evidence from galaxy statistics for either a homogeneous and isotropic universe in one case, and for a mono-fractal universe in the other, are presented and discussed. I also present the method and results of a newer data analysis that shows that visible matter provides no evidence that would allow us to claim that the cosmological principle holds, or that the universe is fractal (or multifractal). In other words, observational data provides us with no evidence that the universe is either homogeneous and isotropic, or monofractal.
Intermittency and Scaling in Cascading Random Transport
Authors: Takayasu Hideki , Terasawa Yasuo
Published: August 2003

We analyze statistical properties of a directed random transport model which can be viewed as a simplest model for turbulent energy cascade in wave number space. A new scaling relation consistent with the known intermittency properties is derived as an asymptotic relation.
Fractal Analysis of Ionospheric Plasma Motion
Authors: Revathy K. , Nayar S. R. Prabhakaran
Published: August 2003

The plasma motion in the ionospheric F region has been subjected to fractal analysis. The fractal dimension of the observed data was obtained by both Fourier and fractal methods. The computational complexity of the two methods has been compared. It is shown that the data processing task for a large amount of data can be characterized by using both the fractal and Fourier methods.
Correlations in Computer Programs
Authors: Novak Miroslav M.
Published: August 2003

Numerical and statistical methods are used to analyze and classify computer programs. Both computer source code and object files are examined. The results of the application of the Pearson and Spearman correlation methods to the source code are coupled with the random walk model applied to the binary code. One of the practical consequences of the analysis is the ability to quantify the degree of similarity between different computer programs and, hence, identify cases of plagiarism.
Anomalous Diffusion on the Percolating Networks
Authors: Liu De , Li Houqiang , Chang Fuxuan , Lin Libin
Published: August 2003

According to the standard diffusion equation, by introducing reasonably into an anomalous diffusion coefficient, the generalized diffusion equation, which describes anomalous diffusion on the percolating networks with a power-law distribution of waiting times, is derived in this paper. This solution of the generalized diffusion equation is obtained by using the method, which is used by Barta. The problems of anomalous diffusion on percolating networks with a power-law distribution of waiting times, which are not solved by Barta, are resolved.
Computer Simulation Study of Silver Deposition from its Aqueous Solution in High Gradient Magnetic Field
Authors: Duan Wenyong , Yano Hiroshi , Tanimoto Yoshifumi
Published: August 2003

The magnetic field effect on the silver deposition pattern generated from Ag +/ Cu redox reaction is simulated with the aid of a biased random walk model. In the model. In the model, one particle that represents an Ag + ion is generated at the same time, and it walks randomly under the influence of a magnetic force. Comparing the simulated pattern with the experimental one, it is confirmed that the convection induced by the magnetic force contributes chiefly to the silver deposition pattern in a high gradient magnetic field.
Time Correlation Structure in Hourly Concentration Time Series of CO, NOx and O3 in Urban Areas
Authors: Lanfredi M. , Macchiato M. , Ragosta M. , Serio C.
Published: August 2003

The timescales which govern urban pollution processes are investigated by analyzing variance spectra and structure functions of observational time series. The range of analyzed scales stretches from one hour to several days. It is shown that characteristic fluctuations of CO, NOx (primary pollutants) and O3 (secondary pollutant) follow a scale invariant law up to timescales of about one day. Scaling exponents indicate the presence of stabilizing feedback mechanisms. Such a scale invariance is broken by the appearance of basic periods which, for primary pollutants, are expressions of traffic dynamics, whereas, for ozone, are closely linked to the diurnal and annual solar cycles.
Multifractality of Air Transmittency at Small Time Scales
Authors: Serio M. , Bergamasco L. , Onorato M. , Osborne A. R. , Alessio S. , Richiardone R. , Longhetto A.
Published: August 2003

The fluctuations of air transmittency over small time scales (20–500 s), in the presence and the absence of fog, are analyzed from different points of view: Fourier and wavelet transforms, multiscaling exponents, the multifractal spectrum and structure functions. All results indicate a multifractal structure associated with intermittency, and whose characteristics do not seem to change with the level of visibility. The origin of this multifractality, whether statistical or dynamical, cannot be established with certainty: there are however indications in favor of the presence of chaos.
Comparison of Three Models of Polymer Erosion — in vivo, in vitro and Computer Simulation — Using Fractal Analysis
Authors: Buczkowski Stéphane , Hildgen Patrice , Cartilier Louis
Published: August 2003

Polyurethane foam has been examined extensively because of its use in many implantable devices. The influence of different environments on polymer structure has been investigated via a number of clinical studies, animal models, in vitro experiments and mathematical models to predict biomaterial behavior. In this work, we employed image analysis and fractal geometry in three models of polymer degradation. In the in vivo and in vitro degradation models, we observed structural collapse and thinning of the polymer backbone, which resulted in a decrease of fractal dimension. Also, an original graphic model was developed. This computer-simulated erosion model was generated by pixel withdrawal from images. A relative degree of erosion is attributed each time an erosion process is applied. Thus, these degrees of erosion can be associated with a general time-related operation. With the computer-simulated erosion model, an unambiguous relationship was demonstrated between the estimation of fractal dimension and the relative degree of erosion. Since such models are based on a loss of mass, the results of fractal dimension were plotted against image surface, allowing us to compare the three different sets of experiments. In all three models, a proportional relationship was found between fractal dimension and image surface. Indeed, the erosion process was well-characterized by decreased fractal dimension since it is a mass dimension. Finally, we showed that the combination of a graphic computer model and a box-counting algorithm is reliable for the quantification of surface erosion.
The Parameter Spaces of the Cubic Polyomials
Authors: Liaw Sy-Sang
Published: August 2003

We plot the two-dimensional projections of the parameter spaces of the cubic mappings. The projection of the parameter points that have non-totally disconnected Julia sets can be seen as a combination of Mandelbrot-like sets. The regularities of these projections with respect to parameters are explained using elementary analysis.
The Chaotic Attractor of the Sediment Movement
Authors: Chen Fengsu , Xue Kongxian , Cai Wenkang
Published: August 2003

We consider the chaotic behavior of the sediment movement with the observed data of the Yangtze River in China and the method of the reconstructed phase space and we find that in the sediment movement there is an attractor. As far as the real example mentioned in this paper is concerned, the correlation dimension and the largest Lyapunov exponent are around 6.6 and 0.013 respectively. These results are crucially referential for estimating the mode of the sediment movement, designing the scheme of the sediment observation, and studying the predictability problem of the sediment.
Discrimination of the Healthy and Sick Cardiac Autonomic Nervous System by a New Wavelet Analysis of Heartbeat Intervals
Authors: Ashkenazy Y. , Lewkowicz M. , Levitan J. , Moelgaard H. , Thomsen P. E. Bloch , Saermark K.
Published: August 2003

We demonstrate that it is possible to distinguish with a complete certainty between healthy subjects and patients with various dysfunctions of the cardiac nervous system by way of multiresolutional wavelet transform of RR intervals. We repeated the study of Thurner et al. on different ensemble of subjects. We show that reconstructed series using a filter which discards wavelet coefficient related with higher scales enables one to classify individuals for which the method otherwise is inconclusive. We suggest a delimiting diagnostic value of the standard deviation of the filtered, reconstructed RR interval time series in the range of ~ 0.035 (for the above mentioned filter), below which individuals are at risk.
Application of Vector Space Techniques to DNA
Authors: Bíró T. , Czirók A. , Vicsek T. , Major Á.
Published: August 2003

We propose the application of a recent vector space technique for the analysis of DNA sequences. In this approach the similarity of two series of symbols is measured by the dot products of vectors corresponding to the given sequences. In this paper we demonstrate that this measure, depending on the short-range properties of the sequences, may be used for identifying different elements of the genome.