bluuebunny/crossref_metadata_2025 huggingface dataset:
Geometry Analysis and Simulation in Shoe Centerless Grinding
Authors: Zhang Hong , Lieh Jungshen , Yen David , Song Xiaozhong , Rui Xiaojian
Published: April 2003

In this paper, the geometry relationship of shoe centerless grinding for predicting the profile of workpiece is presented. Based on the model, critical parameters are studied. The model was compared with experimental results obtained from grinding trials.
Detection of Wheel and Workpiece Contact/Release in Reciprocating Surface Grinding
Authors: Razavi H. Ali , Kurfess Thomas R.
Published: April 2003

This paper evaluates the performance and limitations of a simple algorithm to detect contact and release events in reciprocating surface grinding by processing the output of a piezoelectric force transducer. It efficiently detects these events independent of workpiece material, wheel type, or grinding conditions (except for dry grinding with low material removal rates). The purpose of this algorithm is to prevent force overshoot at the beginning of engagement in the study of subsurface plastic deformation.
A New Approach for Studying Mechanical Properties of Thin Surface Layers Affected by Manufacturing Processes
Authors: Moylan S. P. , Kompella S. , Chandrasekar S. , Farris T. N.
Published: April 2003

Nano-indentation has become an important tool in the study of mechanical properties of solids at small length scales, ever since its formulation as a technique in the early 1980s. The small size of an indentation, typically one micrometer or less in surface extent, makes it a potentially attractive tool also for the quantitative study of the characteristics of surface layers in monolithic solids. Here, we report results from a study in which nano-indentation has been combined with taper-sectioning to analyze the mechanical properties of thin surface layers affected by manufacturing processes. The so-called white etching layer (WL) produced in steel surfaces by machining and abrasion is characterized. The WL is found to have a hardness in the range of 11.5–16.2 GPa, which is significantly greater than that of untempered martensite produced by heat treatment processes. These hardness values are close to those measured on steel piano wires. The so-called “burn-layer” produced on ground surfaces of steels is found to have a hardness distribution very similar to that of a white layer, suggesting that the two layers are of the same type. Localized hardening and softening of surface layers, over spatial extents of a few micro-meters, caused by material removal processes are accurately resolved by the combined use of nano-indentation and taper-sectioning. The taper-sectioning/nano-indentation approach is also shown to be a good procedure for characterizing the hardness of PVD-TiN films deposited onto hard metal substrates.
Use of Image Recognition Techniques in the Analysis of Sheet Metal Forming Force Signature Curves
Authors: Doolan Matthew , Kalyanasundaram Shankar , Cardew-Hall Michael , Hodgson Peter
Published: April 2003

A new method of metal stamping force signature analysis is presented, based on the image recognition technique Point Distribution Models (PDMs). The approach is shown to be an effective method for analyzing force signatures, able to identify not only the occurrence of part failures, but also changes in lubrication, material and process settings.
Common Structure of Soluble Amyloid Oligomers Implies Common Mechanism of Pathogenesis
Authors: Kayed Rakez , Head Elizabeth , Thompson Jennifer L. , McIntire Theresa M. , Milton Saskia C. , Cotman Carl W. , Glabe Charles G.
Published: April 2003

Soluble oligomers are common to most amyloids and may represent the primary toxic species of amyloids, like the Aβ peptide in Alzheimer's disease (AD). Here we show that all of the soluble oligomers tested display a common conformation-dependent structure that is unique to soluble oligomers regardless of sequence. The in vitro toxicity of soluble oligomers is inhibited by oligomer-specific antibody. Soluble oligomers have a unique distribution in human AD brain that is distinct from fibrillar amyloid. These results indicate that different types of soluble amyloid oligomers have a common structure and suggest they share a common mechanism of toxicity.
Organic-Inorganic Hybrid Zeolites Containing Organic Frameworks
Authors: Yamamoto Katsutoshi , Sakata Yasuyuki , Nohara Yuki , Takahashi Yoko , Tatsumi Takashi
Published: April 2003

Organic-inorganic hybrid zeolite materials containing an organic framework have been synthesized by partially superseding a lattice oxygen atom by a methylene group. The use of methylene-bridged organosilane as a silicon source gives zeolite materials containing an organic group as lattice (ZOL), with several zeolitic phases such as the MFI and the LTA structures. Through various characterization methods, the presence of methylene frameworks (Si-CH
2
-Si) that replace siloxane bonds (Si-O-Si) has been verified, although the Si-C bonds are partly cleaved to give rise to terminal methyl groups. The shape-selective lipophilicity of a ZOL material indicates that it is not a physical mixture of conventional zeolite and amorphous organic-containing material but contains a genuine organic-inorganic hybrid zeolite.
The Aerodynamics of Free-Flight Maneuvers in
Drosophila
Authors: Fry Steven N. , Sayaman Rosalyn , Dickinson Michael H.
Published: April 2003

Using three-dimensional infrared high-speed video, we captured the wing and body kinematics of free-flying fruit flies as they performed rapid flight maneuvers. We then “replayed” the wing kinematics on a dynamically scaled robotic model to measure the aerodynamic forces produced by the wings. The results show that a fly generates rapid turns with surprisingly subtle modifications in wing motion, which nonetheless generate sufficient torque for the fly to rotate its body through each turn. The magnitude and time course of the torque and body motion during rapid turns indicate that inertia, not friction, dominates the flight dynamics of insects.
Environmental Noise Retards Auditory Cortical Development
Authors: Chang Edward F. , Merzenich Michael M.
Published: April 2003

The mammalian auditory cortex normally undergoes rapid and progressive functional maturation. Here we show that rearing infant rat pups in continuous, moderate-level noise delayed the emergence of adultlike topographic representational order and the refinement of response selectivity in the primary auditory cortex (A1) long beyond normal developmental benchmarks. When those noise-reared adult rats were subsequently exposed to a pulsed pure-tone stimulus, A1 rapidly reorganized, demonstrating that exposure-driven plasticity characteristic of the critical period was still ongoing. These results demonstrate that A1 organization is shaped by a young animal's exposure to salient, structured acoustic inputs—and implicate noise as a risk factor for abnormal child development.
Packing C
60
in Boron Nitride Nanotubes
Authors: Mickelson W. , Aloni S. , Han Wei-Qiang , Cumings John , Zettl A.
Published: April 2003

We have created insulated C
60
nanowire by packing C
60
molecules into the interior of insulating boron nitride nanotubes (BNNTs).For small-diameter BNNTs, the wire consists of a linear chain of C
60
molecules.With increasing BNNT inner diameter, unusual C
60
stacking configurations are obtained (including helical, hollow core, and incommensurate) that are unknown for bulk or thin-film forms of C
60
.C
60
in BNNTs thus presents a model system for studying the properties of dimensionally constrained “silo” crystal structures. For the linear-chain case, we have fused the C
60
molecules to form a single-walled carbon nanotube inside the insulating BNNT.
Watson's World
Authors: Lindee M. Susan
Published: April 2003

DNA
The Secret of Life. James D. Watson, with Andrew Berry. Knopf, New York, 2003. 462 pp. $39.95, C$59.95. ISBN 0-375-41546-7.

Watson and DNA
Making a Scientific Revolution. Victor K. McElheny. Perseus, Cambridge, MA, 2003. 379 pp. $27.50, C$42.95. ISBN 0-7382-0341-6.

McElheny and Watson offer two perspectives of the growth, status, and prospects of molecular biology. McElheny's biography follows Watson through the discovery of the structure of DNA, the development of the Cold Spring Harbor Laboratory, and the Human Genome Project. Watson's own account for the general reader stresses our current understanding of genetics and its consequences.
PARALLEL INVADED CLUSTER ALGORITHM FOR THE ISING MODEL
Authors: CHOI Y. S. , MACHTA J. , TAMAYO P. , CHAYES L. X.
Published: April 2003

A parallel version of the invaded cluster algorithm is described. Results from large scale (up to 40962 and 5123) simulations of the Ising model are reported. No evidence of critical slowing down is found for the three-dimensional Ising model. The magnetic exponent is estimated to be 2.482±0.001(β/ν=0.518±0.001) for the three-dimensional Ising model.
GRAPHICAL PRESENTATION OF ALPHA-DECAY PROCESSES
Authors: CHA MOON H. , KIM YEONG E.
Published: April 2003

We illustrate wavefunctions and half-lives of α-radioactive even-A thorium isotopes based on the simple semi-classical theory of alpha-decay process. The potential is assumed to take an attractive square-well form inside the potential barrier and to take a repulsive Coulomb one outside the barrier. Overall for the even-A thorium isotopes, only two parameters r0=1.14 fm and V0=16 MeV are used. Outside the region of a potential barrier, an obvious oscillating feature of wavefunction for 218 Th nucleus does not appear until the Qα value is less than 20 MeV. Such a characteristic feature is confirmed by the three dimensional surface plot for the wave function of 218 Th nucleus. Our predicted values of half-life for even-A thorium isotopes are agreed satisfactorily with the observed results as a whole.
CONCEPTUAL FOUNDATIONS OF QUANTUM MECHANICS: THE ROLE OF EVIDENCE THEORY, QUANTUM SETS, AND MODAL LOGIC
Authors: RESCONI GERMANO , KLIR GEORGE J. , PESSA ELIANO
Published: April 2003

Recognizing that syntactic and semantic structures of classical logic are not sufficient to understand the meaning of quantum phenomena, we propose in this paper a new interpretation of quantum mechanics based on evidence theory. The connection between these two theories is obtained through a new language, quantum set theory, built on a suggestion by J. Bell. Further, we give a modal logic interpretation of quantum mechanics and quantum set theory by using Kripke's semantics of modal logic based on the concept of possible worlds. This is grounded on previous work of a number of researchers (Resconi, Klir, Harmanec) who showed how to represent evidence theory and other uncertainty theories in terms of modal logic. Moreover, we also propose a reformulation of the many-worlds interpretation of quantum mechanics in terms of Kripke's semantics. We thus show how three different theories — quantum mechanics, evidence theory, and modal logic — are interrelated. This opens, on one hand, the way to new applications of quantum mechanics within domains different from the traditional ones, and, on the other hand, the possibility of building new generalizations of quantum mechanics itself.
BROAD HISTOGRAM METHOD FOR CONTINUOUS SYSTEMS: THE XY-MODEL
Authors: MUÑOZ JOSÉ D. , HERRMANN HANS J.
Published: April 2003

We propose a way of implementing the Broad Histogram Monte Carlo method to systems with continuous degrees of freedom, and we apply these ideas to investigate the three-dimensional XY-model with periodic boundary conditions. We have found an excellent agreement between our method and traditional Metropolis results for the energy, the magnetization, the specific heat and the magnetic susceptibility on a very large temperature range. For the calculation of these quantities in the temperature range 0.7<T<4.7 our method took less CPU time than the Metropolis simulations for 16 temperature points in that temperature range. Furthermore, it calculates the whole temperature range 1.2<T<4.7 using only 2.2 times more computer effort than the Histogram Monte Carlo method for the range 2.1<T<2.2. Our way of treatment is general; it can also be applied to other systems with continuous degrees of freedom.
INFLUENCE OF BOUNDARY CONDITIONS ON THE FRACTION OF SPANNING CLUSTERS
Authors: FORD MATT , HUNTER D. L. , JAN NAEEM
Published: April 2003

We use the Hoshen–Kopelman algorithm with the Nakanashi method of recycling redundant labels to measure the fraction of spanning configurations, R(pc), at and near pc, for random site percolation in two and three dimensions with different boundary conditions. For the square and cubic lattices we find that R(pc) is 0.50 and 0.28 for free edges and 0.64 (2-d) and 0.56 (3-d) for both helical and periodic boundary conditions. The error bars are of the order of ±0.01 for these results.
PHASE DIAGRAM OF A LOOP ON THE SQUARE LATTICE
Authors: GUO WENAN , BLÖTE HENK W. J. , NIENHUIS BERNARD
Published: April 2003

The phase diagram of the O (n) model, in particular the special case n=0, is studied by means of transfer-matrix calculations on the loop representation of the O (n) model. The model is defined on the square lattice; the loops are allowed to collide at the lattice vertices, but not to intersect. The loop model contains three variable parameters that determine the loop density or temperature, the energy of a bend in a loop, and the interaction energy of colliding loop segments. A finite-size analysis of the transfer-matrix results yields the phase diagram in a special plane of the parameter space. These results confirm the existence of a multicritical point and an Ising-like critical line in the low-temperature O (n) phase.
GLASS MODEL, HUBBARD MODEL AND HIGH-TEMPERATURE SUPERCONDUCTIVITY
Authors: MORGENSTERN INGO , FETTES WERNER , HUSSLEIN THOMAS , NEWNS DENNIS M. , PATTNAIK PRATAP C.
Published: April 2003

In this paper we revisit the glass model describing the macroscopic behavior of the High-Temperature superconductors. We link the glass model at the microscopic level to the striped phase phenomenon, recently discussed widely. The size of the striped phase domains is consistent with earlier predictions of the glass model when it was introduced for High-Temperature Superconductivity in 1987. In an additional step we use the Hubbard model to describe the microscopic mechanism for d-wave pairing within these finite size stripes.

We discuss the implications for superconducting correlations of the Hubbard model, which are much higher for stripes than for squares, for finite size scaling, and for the new view of the glass model picture.
LATERAL DIFFUSION OF FLEXIBLE LIPID CHAINS: A DYNAMIC MONTE CARLO STUDY
Authors: SINTES T. , BAUMGÄRTNER A. , LEVINE Y. K.
Published: April 2003

A computer simulation study of the lateral diffusion of conformationally-disordered lipid molecules in a monolayer structure is reported. The simulations were carried out with dynamic Monte Carlo methods, employing two different representations of the internal motions of the lipid chains. The results indicate that the dependence of the lateral diffusion coefficients on the density (area-per-molecule) in the monolayer is determined by the conformational behavior of the lipid chains. The classical Cohen–Turnbull theory is found to provide a good description of the simulated lateral diffusion coefficients at moderate densities. The substantial deviations found at low densities are attributed to the small density fluctuations creating the free volume needed for the lateral diffusion process.
ORIENTATION CORRELATION IN SIMPLIFIED MODELS OF POLYMER MELTS
Authors: FALLER ROLAND , PÜTZ MATHIAS , MÜLLER-PLATHE FLORIAN
Published: April 2003

We investigate mutual local chain order in systems of fully flexible polymer melts in a simple generic bead-spring model. The excluded-volume interaction together with the connectivity leads to local ordering effects which are independent of chain length between 25 and 700 monomers, i.e. in the Rouse as well as in the reptation regime. These ordering phenomena extend to a distance of about 3 to 4 monomer sizes and decay to zero afterwards.
VIRIAL COEFFICIENTS FOR THE HARD GAUSSIAN OVERLAP MODEL
Authors: HUANG SSU-LI , BHETHANABOTLA VENKAT R.
Published: April 2003

Monte Carlo estimates of virial coefficients up to the sixth for the Hard Gaussian Overlap (HGO) model are presented for values of the aspect ratio parameter κ of the model ranging from 0.05 to 10. The sixth coefficients are new and the lower coefficients are improvements on previous numerical estimates. The second virials are found to be in excellent agreement with an analytical integration reported in the literature. Padé (3, 3) approximations to the pressure and residual Helmholtz energy were constructed. Attempts to represent coefficients in these approximations by analytical functions of κ were not successful due to singularities in these functions. In the approximate range of 4.5≤κ≤ 5.5, the (3, 3) Padé approximations were found to be no better than lower ones. Comparisons with available Monte Carlo simulated pressures for moderately aspherical fluids were found to be good.
A STOCHASTIC CAGE MODEL FOR THE ORIENTATIONAL DYNAMICS OF SINGLE MOLECULES IN NEMATIC PHASES
Authors: FREZZATO DIEGO , SAIELLI GIACOMO , POLIMENO ANTONINO , NORDIO PIER LUIGI
Published: April 2003

A stochastic cage model for the orientational dynamics of a molecule in isotropic and nematic phases of a liquid crystal has been developed, following the methodology introduced in Refs. 1, 2. The model has been parameterized on the basis of statistical data obtained from the analysis of Molecular Dynamics (MD) simulations of a Gay–Berne mesogen and is based on the general assumption of a timescale separation between the fast inertial librational motion inside the instantaneous cage potential and the slow diffusive motion of the cage itself. The model is able to reproduce single molecule time correlation functions both for the angular momentum and the reorientation of the long molecular axis of the molecule. A complete description of the dynamics of a Gay–Berne particle is given with a single set of physical parameters, from a very fast (hundreds of femtoseconds) timescale up to a timescale of nanoseconds.
INTERMOLECULAR POTENTIALS IN LIQUID CRYSTALS: COMPARISON BETWEEN SIMULATIONS AND NMR EXPERIMENTS
Authors: SYVITSKI RAYMOND T. , POLSON JAMES M. , BURNELL E. ELLIOTT
Published: April 2003

The anisotropic intermolecular forces responsible for the orientational ordering in liquid crystals are probed by comparing Monte Carlo (MC) simulations with experimental nuclear magnetic resonance (NMR) results for solutes in nematic liquid crystals. In a special liquid crystal mixture where all long-range interactions are assumed to be minimized, the models for short-range interactions which best fit NMR experimental solute order parameters also best fit solute order parameters from MC simulations of hard ellipsoids. This is taken as an indication that in this special mixture the intermolecular potential is dominated by short-range forces. However, for liquid crystals where long-range interactions are important, simulations of hard ellipsoids with point quadrupoles cannot reproduce even the gross effects observed with experimental NMR data.
A DETAILED MONTE CARLO INVESTIGATION OF THE TRICRITICAL REGION OF A BIAXIAL LIQUID CRYSTAL SYSTEM
Authors: CHICCOLI CESARE , PASINI PAOLO , SEMERIA FRANCO , ZANNONI CLAUDIO
Published: April 2003

We study a lattice system of biaxial particles interacting with a second-rank anisotropic potential. We have performed detailed Monte Carlo calculations in the vicinity of the prolate–oblate dual value of molecular biaxiality. Our results confirm the second-order character of the transition in this limiting case.
PERFECT LATTICE PERTURBATION THEORY: A STUDY OF THE ANHARMONIC OSCILLATOR
Authors: BIETENHOLZ W. , STRUCKMANN T.
Published: April 2003

As an application of perfect lattice perturbation theory, we construct an O(λ) perfect lattice action for the anharmonic oscillator analytically in momentum space. In coordinate space, we obtain a set of 2-spin and 4-spin couplings ∝λ, which we evaluate for various masses. These couplings never involve variables separated by more than two lattice spacings. The O(λ) perfect action is simulated and compared to the standard action. We discuss the improvement for the first two energy gaps ΔE1, ΔE2 and for the scaling quantity ΔE2/ΔE1 in different regimes of the interaction parameter, and of the correlation length. For the quartic oscillator — which corresponds to an asymptotically free theory — we also discuss a classically perfect action. The single gaps perform very well, which corresponds to a clearly improved asymptotic scaling. On the other hand, it turns out to be difficult to demonstrate an improvement for the scaling ratio.
CROSSOVER PROPERTIES FROM RANDOM PERCOLATION TO FRUSTRATED PERCOLATION
Authors: CANNAVACCIUOLO LUIGI , DE CANDIA ANTONIO , CONIGLIO ANTONIO
Published: April 2003

We investigate the crossover properties of the frustrated percolation model on a two-dimensional square lattice, with asymmetric distribution of ferromagnetic and antiferromagnetic interactions. We determine the critical exponents ν, γ, and β of the percolation transition of the model, for various values of the density of antiferromagnetic interactions π in the range 0≤π≤0.5. Our data is consistent with the existence of a crossover from random percolation behavior for π=0, to frustrated percolation behavior, characterized by the critical exponents of the ferromagnetic 1/2-state Potts model, as soon as π>0.
A SIMPLE SOLID-ON-SOLID MODEL OF EPITAXIAL FILM GROWTH: SURFACE ROUGHNESS AND DYNAMICS
Authors: MALARZ K. , MAKSYMOWICZ A. Z.
Published: April 2003

The random deposition model must be enhanced to reflect the variety of surface roughness due to some material characteristics of the film growing by vacuum deposition or sputtering. The essence of the computer simulation in this case is to account for possible surface migration of atoms just after the deposition, in connection with the binding energy between atoms (as the mechanism provoking the diffusion) and/or diffusion energy barrier. The interplay of these two factors leads to different morphologies of the growing surfaces, from flat and smooth ones to rough and spiky ones. In this paper, we extended our earlier calculation by applying an extra diffusion barrier at the edges of terrace-like structures, known as the Ehrlich–Schwoebel barrier. It is experimentally observed that atoms avoid descending when the terrace edge is approached, and these barriers mimic this tendency. Results of our Monte Carlo computer simulations are discussed in terms of surface roughness, and compared with other model calculations and some experiments from literature. The power law of the surface roughness σ against film thickness t was confirmed. The nonzero minimum value of the growth exponent β near 0.2 was obtained which is due to the limited range of the surface diffusion and the Ehrlich–Schwoebel barrier. Observations for different diffusion ranges are also discussed. The results are also confirimed with some deterministic growth models.
GROUND STATES FOR LARGE SAMPLES OF TWO-DIMENSIONAL ISING SPIN GLASSES
Authors: PALMER R. G. , ADLER JOAN
Published: April 2003

We have developed a combinatoric matching method to find the exact groundstate energy for the 2-D Ising spin glass with the ± J distribution and equal numbers of positive and negative bonds. For the largest size (1800×1800 plaquettes of spins), we averaged results from 278 samples and for the smaller ones up to 374, 375 samples. We also studied the behavior of the distributions of computer time (CPU) and memory as functions of sample size. We present finite size scaling leading to a groundstate energy estimate of E∞=-1.40193±2 for the infinite system. We found that the memory scales as the square of sample length and that for a given size, the CPU time appears to have a skewed and high-tailed distribution.
A NETWORK OF CELLULAR AUTOMATA FOR THE SIMULATION OF THE IMMUNE SYSTEM
Authors: CASTIGLIONE F. , MANNELLA G. , MOTTA S. , NICOSIA G.
Published: April 2003

We propose a new computational scheme of the Celada–Seiden model ( CS model ) for the simulation of the Immune System response. This new approach is closer to the classical definition of cellular automata than the previous one. It has the advantage of achieving the same results obtained with the CS model (IMMSIM) with a lower computational effort.
VIRGINIA OPOSSUMS, MINIMUM REPRODUCTION AGE AND PREDATORS IN THE PENNA AGING MODEL
Authors: ALTEVOLMER A. K.
Published: April 2003

Age-specific predators are introduced into the Penna model of biological aging. It is shown that populations with a variable minimum reproduction age find a stable state with an earlier onset of reproduction, if older ages are eaten by the predators. This behavior agrees with the demographic data of the Virgina opossum.
CRITICAL CRASHES?
Authors: ILINSKI KIRILL
Published: April 2003

In this short note, we discuss recent attempts to describe pre-crash market dynamics with analogies from the theory of critical phenomena.
A PARALLEL FAST FOURIER TRANSFORM
Authors: MORANTE SILVIA , ROSSI GIANCARLO , SALINA GAETANO
Published: April 2003

In this paper we discuss the general problem of implementing the multidimensional Fast Fourier Transform algorithm on parallel computers. We show that, on a machine with P processors and fully parallel node communications, the optimal asymptotic scaling behavior of the total computational time with the number of data points, N, given in d dimensions by the formula aN/P log (N/P)+bN/P(d-1)/d, can actually be achieved on realistic platforms. As a concrete realization of our strategy, we have produced codes efficiently running on machines of the APE family and on Cray T3E. On the former for asymptotic values of N our codes attain the above optimal result.
ISING MODEL AS TEST FOR SIMPLE RANDOM NUMBER GENERATORS
Authors: STAUFFER DIETRICH
Published: April 2003

Monte Carlo simulations with up to 1765 spins show no significant deviations between four different random number generators in multispin coding, as opposed to multiplication with 16807 for one-word-per-spin coding for 325. Also world record sizes 10001922, 99843, 8804 and 486 spins were simulated.
EPILEPTIC SEIZURES IN A DISCRETE MODEL OF NEURAL NETWORKS OF THE BRAIN
Authors: VOLK DANIEL
Published: April 2003

A discrete model of a neural network of excitatory and inhibitory neurons is presented which yields oscillations of its global activity. Different types of dynamics occur depending on the selection of parameters: oscillating population activity as well as randomly fluctuating but mainly constant activity. For certain sets of parameters the model also shows temporary transitions from apparently random to periodic behavior in one run, similar to an epileptic seizure.
EXPONENTIALLY-FITTED RUNGE–KUTTA THIRD ALGEBRAIC ORDER METHODS FOR THE NUMERICAL SOLUTION OF THE SCHRÖDINGER EQUATION AND RELATED PROBLEMS
Authors: SIMOS T. E. , WILLIAMS P. S.
Published: April 2003

Exponentially and trigonometrically fitted third algebraic order Runge–Kutta methods for the numerical integration of the Schrödinger equation are developed in this paper. Numerical results obtained for several well known problems show the efficiency of the new methods.
A FINITE-SIZE SCALING STUDY OF THE FOUR-DIMENSIONAL ISING MODEL ON THE CREUTZ CELLULAR AUTOMATON
Authors: AKTEKIN N. , GÜNEN A. , SAĞLAM Z.
Published: April 2003

The four-dimensional Ising model is simulated on the Creutz cellular automaton with increased precision. The data are analyzed according to the finite-size scaling relations available. The precision of the critical values related to magnetic susceptibility is improved by one digit, but in order to reach to the same precision for those related to the specific heat more simulation runs at the critical temperatures of the finite-size lattices are required.
CAPILLARY CONDENSATION OF A FLUID IN A SLIT-LIKE PORE FILLED WITH OBSTACLES: LATTICE MONTE CARLO SIMULATION
Authors: RŻYSKO W. , PIZIO O. , SOKOŁOWSKI S.
Published: April 2003

We study the capillary condensation of a lattice gas with nearest neighbor attraction confined to a slit-like pore filled with frozen obstacles (matrix). First, the lattice Monte Carlo simulations were performed for a slit-like pore without obstacles. Next, the pore filled with obstacles, i.e., confined microporous medium, is prepared by adsorbing and then by quenching a hard sphere fluid in the pore of the width H. The model includes fluid-wall attraction; however, the fluid-matrix interaction is entirely repulsive. We have investigated how concentration of obstacles and the pore width H influence the capillary phase diagrams. Our numerical experiments reveal essential changes in the critical temperature and in the shape of the coexistence line with the amount of quenched obstacles.
TEST OF DOMANY–SWENDSEN HYPOTHESIS FOR 2D KINETIC ISING MODEL
Authors: STAUFFER DIETRICH
Published: April 2003

The hypothesis z=2 with logarithmic corrections seems inconsistent with one way of simulation but not with a different one, for the same Ising model.
LATTICE THREE-SPECIES MODELS OF THE SPATIAL SPREAD OF RABIES AMONG FOXES
Authors: BENYOUSSEF A. , BOCCARA N. , CHAKIB H. , EZ-ZAHRAOUY H.
Published: April 2003

Lattice models describing the spatial spread of rabies among foxes are studied. In these models, the fox population is divided into three-species: susceptible (S), infected or incubating (I), and infectious or rabid (R). They are based on the fact that susceptible and incubating foxes are territorial while rabid foxes have lost their sense of direction and move erratically. Two different models are investigated: a one-dimensional coupled-map lattice model, and a two-dimensional automata network model. Both models take into account the short-range character of the infection process and the diffusive motion of rabid foxes. Numerical simulations show how the spatial distribution of rabies, and the speed of propagation of the epizootic front depend upon the carrying capacity of the environment and diffusion of rabid foxes out of their territory.
ISING CLUSTER FRAGMENTATION AT THE CRITICAL POINT
Authors: HEO MUYOUNG , CHEON MOOKYUNG , CHANG IKSOO , STAUFFER DIETRICH
Published: April 2003

The scaling law of Edwards et al., for cluster fragmentation of critical percolation clusters is not confirmed by analogous Monte Carlo simulations at the Curie point of the two-dimensional Ising model.
RIPPLES VERSUS GIANT DUNES IN A SALTATION-AVALANCHE MODEL
Authors: VANDEWALLE NICOLAS , GALAM SERGE
Published: April 2003

A simple stochastic cellular automaton model is proposed for ripples and dunes formation. Saltation and avalanches are the unique ingredients of the model. The dynamics of ripple formation is found to be logarithmic in time while the ripple merging as well as the dune growth is faster and occurs by bursts. The ripple state turns out to be metastable.
NO DECOMPOSITION ON TRANSITION METALS: A MONTE CARLO SIMULATION
Authors: BUSTOS V. A. , ZGRABLICH G.
Published: April 2003

The kinetics of NO decomposition on transition metals is studied through Monte Carlo simulation, including the effects of adsorbate-adsorbate interactions and of surface energetic heterogeneity. For a homogeneous surface, it is found that previous quasi-chemical approximation calculations are reasonably in agreement with Monte Carlo results except for strong repulsive interactions. In this last case, quasi-chemical predictions largely overestimate the decomposition rate. It is found that energetic heterogeneity introduces interesting behaviors which depend on the energetic topography considered.
EFFECT OF MIGRATION ON POPULATION DYNAMICS
Authors: MAGDOŃ MARIA S.
Published: April 2003

Computer studies of evolution in migrating population are presented. The model is based on the Penna model. Migration for better living conditions does influence population dynamics in different locations. Examples of different scenarios of preferences to live in bigger or smaller populations (or environmental capacity, or living space available) are discussed. In the limiting case of low migration intensity, each location evolves independently according to its local rules and conditions, as expected. With increasing migration, the population distribution between locations changes, including the critical behavior of extinction of population for some locations for a specific set of the rules. Then, the deserted location may become populated again if the migration is still increasing as result of a pressure to move. The present version is devoted to the migration controlled exclusively by environmental factors, yet the model is primarily designed to describe both inherited mutations on environmental factors and can be used to study the effect of different races mixing, or recovery of environmental capacity of the fields when chasing 2 flocks of geese in a cyclic manner across 3 fields.
VIBRONIC EXTENDED HÜCKEL THEORY AND THE FORCES IN MOLECULES
Authors: LETELIER JORGE RICARDO
Published: April 2003

A method is presented that allows the computation of the forces acting on the atoms in a molecule along each of the symmetry nuclear displacements coordinates. The method works within the Extended Hückel formalism and makes use of the standard output of a charge-iterated calculation. In this work, examples are given of the different contributions to the total force, arising from the populated molecular orbitals, that act on the atoms in several diatomic molecules and the shape of the vibrational potential is analyzed. Also, the distortions (Peierls) that take place in a linear triatomic system of hydrogen atoms is also examined under this viewpoint.
AN INVESTIGATION OF SITE-BOND PERCOLATION ON MANY LATTICES
Authors: TARASEVICH YURIY YU. , VAN DER MARCK STEVEN C.
Published: April 2003

A calculation of site-bond percolation thresholds in many lattices in two to five dimensions is presented. The line of threshold values has been parametrized in the literature, but we show here that there are strong deviations from the known approximate equations. We propose an alternative parametrization that lies much closer to the numerical values.
SIMPLE AND EFFICIENT ALGORITHM FOR LARGE SCALE MOLECULAR DYNAMICS SIMULATION IN HARD DISK SYSTEM
Authors: ISOBE MASAHARU
Published: April 2003

A simple and efficient algorithm of the molecular-dynamics simulation of the hard disk system based on the Event-Driven method is developed. From the analysis of algorithm, the complexity is [Formula: see text] per 1 event, and the constant coefficient of the complexity is smaller than conventional efficient algorithm based on the concept of Cell-Crossing Event. The maximum performance of more than 460 millions of collisions per CPU-hour on the Alpha600 compatible in a 2500 particle system is achieved. An extension to the infinite-space system based on this algorithm is also proposed.
COMPUTERIZED SYMBOLIC COMPUTATION FOR THE CYLINDRICAL KORTEWEG–DE VRIES EQUATION
Authors: GAO YI-TIAN , TIAN BO
Published: April 2003

Computers have a great potential in the analytical investigations on various physics problems. In this paper, we make use of computerized symbolic computation to obtain two similarity reductions as well as a rational solution for the variable-coefficient cylindrical Korteweg–de Vries equation, which was originally introduced in the studies of plasma physics. One of the reductions is to the second Painlevé equation, while the other to either the first Painlevé equation or the Weierstrass elliptic function equation. Our results are in agreement with the Painlevé conjecture.
TOOLS FOR QUANTUM ALGORITHMS
Authors: HOGG TAD , MOCHON CARLOS , POLAK WOLFGANG , RIEFFEL ELEANOR
Published: April 2003

We present efficient implementations of a number of operations for quantum computers. These include controlled phase adjustments of the amplitudes in a superposition, permutations, approximations of transformations and generalizations of the phase adjustments to block matrix transformations. These operations generalize those used in proposed quantum search algorithms.
ENERGY CONSERVING DISCRETE BOLTZMANN EQUATION FOR NONIDEAL SYSTEMS
Authors: MARTYS NICOS S.
Published: April 2003

The BBGKY formalism is utilized to obtain a set of moment equations to be satisfied by the collision operator in an energy conserving discrete Boltzmann equation for the case of a nonlocal interaction potential. A modified BGK form of the collision operator consistent with these moment equations is described. In the regime of isothermal flows, a previous proposed nonideal gas model is recovered. Other approaches to constructing the collision operator are discussed. Numerical implementation of the modified BGK form, using a thermal lattice Boltzmann model, is illustrated as an example. The time dependence of the density autocorrelation function was studied for this model and found, at early times, to be strongly affected by the constraint of total energy conservation. The long time behavior of the density autocorrelation function was consistent with the theory of hydrodynamic fluctuations.
QUANTUM MONTE CARLO STUDY OF SITE-DILUTED HEISENBERG ANTIFERROMAGNET ON A SQUARE LATTICE
Authors: TODO S. , KATO K. , TAKAYAMA H. , HARADA K. , KAWASHIMA N. , MIYASHITA S.
Published: April 2003

Ground-state phase transition of site-diluted Heisenberg antiferromagnets on a square lattice is studied. By using the continuous-time loop algorithm, we perform large-scale quantum Monte Carlo simulation on large systems at quite low temperatures. It is found that the critical concentration of magnetic sites is independent of the spin size S, and equal to the classical percolation threshold. However, the existence of quantum fluctuations makes the critical exponents deviate from those of the classical percolation transition. It is found that the transition is not universal, i.e., the critical exponents depend on the spin size S.
QUANTUM MONTE CARLO METHODS IN STATISTICAL MECHANICS
Authors: MELIK-ALAVERDIAN VILEN , NIGHTINGALE M. P.
Published: April 2003

This paper deals with the optimization of trial states for the computation of dominant eigenvalues of operators and very large matrices. In addition to preliminary results for the energy spectrum of van der Waals clusters, we review results of the application of this method to the computation of relaxation times of independent relaxation modes at the Ising critical point in two dimensions.
RELAXATION OF METASTABLE STATES BY QUANTUM FLUCTUATION
Authors: MIYASHITA S. , SAITO K.
Published: April 2003

An investigation for numerical method to study quantum dynamics in dissipative environments is presented, studying the resonant tunneling phenomena of the low temperature magnetization process of Mn 12. It is pointed out that information of pure quantum transition can be obtained from deceptive nonadiabatic transitions due to the dissipative environments.
MONTE CARLO SIMULATIONS OF DOPED, DILUTED MAGNETIC SEMICONDUCTORS — A SYSTEM WITH TWO LENGTH SCALES
Authors: BHATT R. N. , WAN XIN
Published: April 2003

We describe a Monte Carlo simulation study of the magnetic phase diagram of diluted magnetic semiconductors doped with shallow impurities in the low concentration regime. We show that because of a wide distribution of interaction strengths, the system exhibits strong quantum effects in the magnetically ordered phase. A discrete spin model, found to closely approximate the quantum system, shows long relaxation times, and the need for specialized cluster algorithms for updating spin configurations. Results for a representative system are presented.
DYNAMICAL ASPECTS OF EQUILIBRIUM AND OFF-EQUILIBRIUM SIMULATIONS OF A THREE-DIMENSIONAL HEISENBERG SPIN GLASS
Authors: KAWAMURA H. , HUKUSHIMA K.
Published: April 2003

Spin-glass and chiral-glass orderings of a three-dimensional isotropic Heisenberg spin glass are studied both by equilibrium and off-equilibrium Monte Carlo simulations with emphasis on their dynamical aspects. The model is found to exhibit a finite-temperature chiral-glass transition without the conventional spin-glass order. Although chirality is an Ising-like quantity from symmetry, universality class of the chiral-glass transition appears to be different from that of the standard Ising spin glass. In the off-equilibrium simulation, while the spin autocorrelation exhibits only an interrupted aging, the chirality autocorrelation persists to exhibit a pronounced aging effect reminiscent of the one observered in the mean-field model.
APPLICATION OF MONTE CARLO METHOD TO PHASE SEPARATION DYNAMICS OF COMPLEX SYSTEMS
Authors: OKABE YUTAKA , MIYAJIMA TSUKASA , ITO TOSHIRO , KAWAKATSU TOSHIHIRO
Published: April 2003

We report the application of the Monte Carlo simulation to phase separation dynamics. First, we deal with the phase separation under shear flow. The thermal effect on the phase separation is discussed, and the anisotropic growth exponents in the late stage are estimated. Next, we study the effect of surfactants on the three-component solvents. We obtain the mixture of macrophase separation and microphase separation, and investigate the dynamics of both phase separations.
LARGE SCALE LONG-LIVED HETEROGENEITY IN THE DYNAMICS OF SUPERCOOLED LIQUIDS
Authors: YAMAMOTO RYOICHI , ONUKI AKIRA
Published: April 2003

The local mobility of particles in highly supercooled liquids is demonstrated to be spatially heterogeneous on time scales comparable to the structural relaxation time τα. The particle motions in the active regions dominantly contribute to the mean square displacement, giving rise to a diffusion constant systematically larger than the Stokes–Einstein value. The diffusion process eventually becomes homogeneous on time scales longer than the life time of the heterogeneity structure (~ 3τα). The heterogeneity structure in the local mobility is very analogous to the critical fluctuation in Ising spin systems with their structure factor being excellently fitted to the Ornstein–Zernike form.
TRANSITION MATRIX MONTE CARLO
Authors: SWENDSEN ROBERT H. , DIGGS BRIAN , WANG JIAN-SHENG , LI SHING-TE , GENOVESE CHRISTOPHER , KADANE JOSEPH B.
Published: April 2003

Although histogram methods have been extremely effective for analyzing data from Monte Carlo simulations, they do have certain limitations, including the range over which they are valid and the difficulties of combining data from independent simulations. In this paper, we describe a complementary approach to extracting information from Monte Carlo simulations that uses the matrix of transition probabilities. Combining the Transition Matrix with an N-fold way simulation technique produces an extremely flexible and efficient approach to rather general Monte Carlo simulations.
DIAMOND SYNTHESIS WITH HOT FILAMENT CHEMICAL VAPOR DEPOSITION (HFCVD) IN THE PRESENCE OF IRON
Authors: LI C. H. , WANG G. Z. , LIAO Y. , YE F. , FANG R. C.
Published: April 2003

A new substrate pretreatment for the synthesis of diamond with hot filament chemical vapor deposition (HFCVD) is reported. The substrate was prepared by galvanizing a thin layer of iron on porous silicon. Sphere-like diamond was observed, whose surface was embedded by certain surface morphology of diamond. Further more, several high diamond towers were detected, which consist of dozens of diamond spheres. SEM and Micro-Raman spectroscopy confirm the result.
ATOM-OPTICAL BISTABILITY IN TRAPPED BOSE–EINSTEIN CONDENSATES
Authors: CHEN ZENG-BING
Published: April 2003

The close similarities between nonlinear optics and nonlinear atom optics motivate us to demonstrate the possibility of atom-optical bistability for a trapped Bose–Einstein condensate. Driven by an intense, coherent input matter wave, the trapped Bose–Einstein condensate might display the bistability when the Born–Markov master equation for the condensate mode is used. The atom-optical bistability provides a way to control atom lasers with atom lasers.
Gd SUBSTITUTION EFFECT ON THE FORMATION OF Bi-BASED SUPERCONDUCTING GLASS CERAMICS
Authors: POP M. , BORODI GH. , DEAC I. Gr. , SIMON S.
Published: April 2003

The effect of calcium substitution by gadolinium on the superconducting phases formation in BSCCO-type compounds is studied by X-ray diffraction and ac susceptibility measurements on the undoped and Gd-doped Bi1.8Pb0.2Sr2CaCu2Oz and Bi1.8Pb0.2Sr2Ca2Cu3Oz systems. The addition of gadolinium to the samples favors the 2212 phase formation in both 2212 and 2223 starting compositions. It is suggested that a correlation exists between the stabilization effect of gadolinium on the 2212 phase formation and the Gd3+ coordination in oxide compounds.
ON THE OPTIMAL NUMBER OF INSTRUCTIONS FOR UNIVERSAL TURING MACHINES CONNECTED WITH A FINITE AUTOMATON
Authors: MARGENSTERN MAURICE , PAVLOTSKAÏA LIOUDMILA
Published: April 2003

In this paper, a new computation system is defined by coupling a finite automaton with a deterministic Turing machine with one head and one tape that is infinite in one direction only. In a first part of the paper, it is shown that there is a Turing machine with five instructions for which it is possible to devise a finite automaton such that the resulting computation is able to simulate any Turing machine. In a second part of the paper it is shown that if the Turing machine has at most four instructions, whatever the finite automaton is, the halting of the resulting computation is always decidable.
PATTERNS THEORY AND GEODESIC AUTOMATIC STRUCTURE FOR A CLASS OF GROUPS
Authors: ELDER MURRAY J.
Published: April 2003

We introduce a theory of patterns in order to study geodesics in a certain class of group presentations. Using patterns we show that there does not exist a geodesic automatic structure for certain group presentations, and that certain group presentations are almost convex.
THE RENNER MONOIDS AND CELL DECOMPOSITIONS OF THE SYMPLECTIC ALGEBRAIC MONOIDS
Authors: LI ZHENHENG , RENNER LEX E.
Published: April 2003

In this paper we explicitly determine the Renner monoid ℛ and the cross section lattice Λ of the symplectic algebraic monoid MSpn in terms of the Weyl group and the concept of admissible sets; it turns out that ℛ is a submonoid of ℛn, the Renner monoid of the whole matrix monoid Mn, and that Λ is a sublattice of Λn, the cross section lattice of Mn.

Cell decompositions in algebraic geometry are usually obtained by the method of [1]. We give a more direct definition of cells for MSpn in terms of the B × B-orbits, where B is a Borel subgroup of the unit group G of MSpn. Each cell turns out to be the intersection of MSpn with a cell of Mn. We also show how to obtain these cells using a carefully chosen one parameter subgroup.