bluuebunny/crossref_metadata_2025 huggingface dataset:
MODIFICATION OF CASIMIR FORCES DUE TO BAND GAPS IN PERIODIC STRUCTURES
Authors: VILLARREAL C. , ESQUIVEL-SIRVENT R. , COCOLETZI G. H.
Published: July 2002

The Casimir force between inhomogeneous slabs that exhibit a band-like structure is calculated. The slabs are made of basic unit cells each made of two layers of different materials. As the number of unit cells increases the Casimir force between the slabs changes, since the reflectivity develops a band-like structure characterized by frequency regions of high reflectivity. This is also evident in the difference of the local density of states between free and boundary distorted vacuum, that becomes maximum at frequencies corresponding to the band gaps. The calculations are restricted to vacuum modes with wave vectors perpendicular to the slabs.
EFFECTS OF CORRELATED NOISES ON CURRENT
Authors: JIA YA , LI JIA-RONG
Published: July 2002

Motivated by recent work on stochastic ratchets, a probability current formula of nonequilibrium system which contains two thermal noises correlated with each other is presented. A simple imaginable ratchet system is discussed, it is found that, when the potential is spatial asymmetry, there are an advanced current reversal phenomenon and a postponed current reversal one as the intensity of correlations between noises varies; when the potential is spatial symmetry, the current reversal occurs at the case of uncorrelation between noises. The system exhibits a current in either direction, and the direction can be controlled by the intensity of the correlations between noises. The current reversal is due to the effects of correlations between noises.
STRIPES IN DOPED ANTIFERROMAGNETS: BOND-CENTERED VERSUS SITE-CENTERED
Authors: ZACHER MARC G. , EDER ROBERT , ARRIGONI ENRICO , HANKE WERNER
Published: July 2002

The single-particle Green's function for a striped t–J model is calculated using cluster a perturbation theory, where short-distance effects are accounted for by exact cluster diagonalization and long-distance effects by perturbation (in the hopping). Both site-centered and bond-centered stripe scenarios have been studied. The data for site-centered stripes quantitatively reproduce salient (ARPES-) features.
RECENT STUDIES OF THE NUCLEAR INTERACTION
Authors: CARLSON J.
Published: July 2002

Recent studies of light p-shell nuclei reveal that so-called 'realistic' nuclear interactions, those based on the NN scattering data augmented with plausible models of the three-nucleon interaction, provide a good description or nuclei through A =8. However, significant discrepancies exist, primarily in the energies of neutron rich systems and in the L.S splittings in the spectra of these nuclei. We briefly describe the methods used in these studies, and describe improved models of the three-nucleon interaction.
CANDIDATES FOR μ<0, ∊<0 NANOSTRUCTURES
Authors: DEWAR G.
Published: July 2002

Recent interest has been generated in composite materials for which both the dielectric constant and the magnetic permeability are negative. These composites behave as if they possess a negative index of refraction, although the broader, less specific adjective "left-handed" has also been applied to them. Such composites possess two sets of structures which are separately responsible for the negative ∊ and μ. However, materials having a negative μ are common in the microwave frequency range and such a material can replace one set of structures in the composite. An example of a simple composite is a YIG medium (μ<0) penetrated by sets of metallic strips or wires which give rise a negative dielectric constant in the appropriate frequency range. The index of refraction of the composite can be modulated by adjusting the applied magnetic field.
PSEUDOGAP PHENOMENA AND THE DENSITY WAVES IN HIGH-Tc CUPRATES
Authors: GHOSH ANGSULA
Published: July 2002

We consider the density waves as possible explanations for the pseudogap in high temperature cuprate superconductors. Both the conventional spin density wave (SDW) and the unconventional d-density waves are considered in our study using a mean-field calculation of the tight binding model including terms upto second nearest neighbor hopping (γ). The phase diagrams for the order parameter and temperature with doping in the above types of density waves are discussed. The d-SDW does not coexist with the superconducting gap when studied with doping whereas the d-charge density wave (DDW) shows a state of coexistence. The temperature dependence of the order parameter and specific heat is also demonstrated. The spectral function of the SDW is also considered for various temperatures and doping.
LOCAL DOMAIN VS. COLLECTIVE DOMAIN: PRECURSORS TO PHOTOINDUCED STRUCTURAL PHASE TRANSITIONS IN COUPLED CHAINS WITH ELECTRON-LATTICE INTERACTION
Authors: IWANO K.
Published: July 2002

An electron-lattice model is proposed as a prototype system simulating photoinduced structural phase transitions. In particular, a coupled-chain system consisting of four chains is studied by both analyses of adiabatic potential surfaces and dynamical simulations. Special emphases are placed on nonlinearity in domain creations with respect to excitation density, intrinsic dissipation, sensitivity to initial conditions, and domain merging.
CRYSTALLIZATION IN AMORPHOUS SILICON
Authors: CHEN L. J. , CHENG S. L. , LIN H. H. , CHI K. S.
Published: July 2002

High-resolution transmission electron microscopy (HRTEM) in conjunction with auto-correlation function (ACF) analysis has been applied to investigate the crystallization processes in amorphous silicon. For both electron beam evaporated and ion implanted amorphous silicon thin films, a high density of Si nanocrystallites was detected in as-deposited films. The density was found to diminish in amorphous films with annealing temperature first then increase. The conclusions are discussed in the context of free energy change with annealing temperature.
ELECTRICAL PROPERTIES OF RARE EARTH SUBSTITUTED Bi6Fe2Ti3O18 COMPOUND
Authors: PRASAD N. V. , PRASAD G. , KUMAR G. S.
Published: July 2002

The Ac conductivity measurements of polycrystalline materials of rare earth substituted Bi 6 Fe 2 Ti 3O18 compound at different frequencies (1 kHz–1 MHz) and temperatures (30–550°C) are reported. The dc conductivity, ionic hoping rate as well as carrier densities have been extracted from the ac conductivity data. The results show that hoping mechanism dominates at lower temperature. The results are discussed.
NUMERICAL PREDICTION OF THE INFLUENCE OF PROCESS PARAMETERS ON LARGE AREA DIAMOND DEPOSITION BY DC ARCJET WITH ARC ROOTS ROTATING AND OPERATING AT GAS RECYCLING MODE
Authors: LU F. X. , HUANG T. B. , TANG W. Z. , SONG J. H. , TONG Y. M.
Published: July 2002

A computer model have been set up for simulation of the flow and temperature field, and the radial distribution of atomic hydrogen and active carbonaceous species over a large area substrate surface for a new type dc arc plasma torch with rotating arc roots and operating at gas recycling mode A gas recycling radio of 90% was assumed. In numerical calculation of plasma chemistry, the Thermal-Calc program and a powerful thermodynamic database were employed. Numerical calculations to the computer model were performed using boundary conditions close to the experimental setup for large area diamond films deposition. The results showed that the flow and temperature field over substrate surface of Φ60-100mm were smooth and uniform. Calculations were also made with plasma of the same geometry but no arc roots rotation. It was clearly demonstrated that the design of rotating arc roots was advantageous for high quality uniform deposition of large area diamond films. Theoretical predictions on growth rate and film quality as well as their radial uniformity, and the influence of process parameters on large area diamond deposition were discussed in detail based on the spatial distribution of atomic hydrogen and the carbonaceous species in the plasma over the substrate surface obtained from thermodynamic calculations of plasma chemistry, and were compared with experimental observations.
STRUCTURAL STUDY OF PZT/YBCO BY TRIPLE-AXES DIFFRACTION
Authors: MAI Z. H. , ZHU A. I. , LIU B. T. , LI C. R. , CUI S. F. , HAO Z. , ZHAO B. R.
Published: July 2002

The structures of Pb ( Zr x Ti 1-x) O 3/ YBCO heterostructure with different thickness of PZT sublayer were investigated. The lattice parameter, c of YBCO layer is obtained to be c=11.686±0.001 Å, being of 0.2% larger than that of the bulk one. The lattice parameter, c of PZT layer is c=4.116±0.001 Å, indicating that the composition of the sample is Pb ( Zr 0.48 Ti 0.52) O 3. The misorientations of YBCO/PZT sublayers were observed in the samples B and D. The effect of the crystalline quality of the STO substrate on the quality of the YBCO and PZT epitaxial films was discussed.
Phenomenology of YBa2Cu3O7-x Grain Boundary Josephson Junctions Irradiated by an Electron Beam
Authors: Tafuri F. , Nadgorny B. , Shokor S. , Gurvitch M. , Carillo F. , Lombardi F. , Di Chiara A. , Sarnelli E.
Published: July 2002

Electron beam irradiation has been used to induce controllable variations in the properties of YBa 2 Cu 3 O 7-x biepitaxial grain boundary Josephson junctions. Electron irradiation decreased the critical current of the junctions IC and increased the normal state specific resistivities. The junction parameters can be adjusted controllably by applying an appropriate dose. The original properties of the junctions could be partly restored by isothermal annealing A correlation between the transport properties and the microstructure was obtained by determining the ratio of a barrier thickness to the dielectric constant of the junctions with different barriers. The experiment also demonstrates frequency tunability in a resonant soliton oscillator. Preliminar results of irradiation on (103) YBCO films have been given demonstrating differences from data on c -axis films, as partly expected from the anisotropy of these materials.
DENSITY OF STATES AND TRANSPORT PROPERTIES IN NORMAL STATE OF CUPRATE-SUPERCONDUCTORS
Authors: BASAK S. , GHATAK S. K.
Published: July 2002

Three-state model for quasi-two dimensional Cu-O layer of oxide superconductor is considered. The density of states and transport properties (resistivity and thermo-electric power) in normal state are calculated for resonance and non-resonance condition of Cu d-level and O p-level. Thermoelectric power can be positive or negative depending on carrier concentration, bare charge transfer gap and transfer integral between d–p and p–p states and its sign changes at higher temperature. The thermo-electric power when positive passes through a maximum with increase in temperature. The value at its maximum and its location moves up with decrease in carrier concentration. The thermal variation of resistivity changes from metallic like (linear in -T) to semiconducting-like as carrier concentration reduces by small amount.
ADVANCE IN DYNAMICAL SPONTANEOUS SYMMETRY BREAKING
Authors: CHENG GENG
Published: July 2002

Recently, a condition is derived for a nontrivial solution of the Schwinger–Dyson equation to be accompanied by a Goldstone bound state in a special quantum electrodynamics model. This result is extended and a new form of the Goldstone theorem is obtained in a general quantum field theory framework.
Spin-orbit scattering in dx2-y2 superconductors
Authors: Graf M. J. , Balatsky A. V. , Sauls J. A.
Published: July 2002

We show that spin-orbit scattering off an isolated magnetic impurity in a singlet dx2-y2 superconductor generates a dxy order parameter with locally broken time-reversal symmetry. A consequence of the induced dxy component are orbital charge currents and a magnetic field in the vicinity of the magnetic impurity.
SQUID MICROSCOPE
Authors: YEH W. J. , CHENG BO
Published: July 2002

We have developed and tested a new type of SQUID microscope, which can operate in magnetic field and at higher temperature. In the system, a single loop coupling transformer made from high-Tc superconducting thin film is used. At one end of the transformer, a small detecting loop about 20 μm can be placed very close to the sample under investigation. At the other end of the transformer, a large loop is tightly coupled with a NbTi coil, which in turn is connected to a low-Tc SQUID. The position of the detecting loop relative to the sample can be remotely controlled. Different sizes of transformer have been tested and calibrated. The results show that the system is capable of detecting a single flux line.
q-DEFORMED DYNAMICS AND JOSEPHSON JUNCTION
Authors: JOHAL RAMANDEEP S.
Published: July 2002

We define a generalized rate equation for an observable in quantum mechanics, that involves a parameter q and whose limit q→1 gives the standard Heisenberg equation. The generalized rate equation is used to study dynamics of current-biased Josephson junction. It is observed that this toy model incorporates diffraction-like effects in the critical current. Physical interpretation for q is provided which is also shown to be a q-deformation parameter.
QUASI-2D VORTEX MEMORY CELLS?
Authors: BELEVTSOV L. V.
Published: July 2002

The model of a memory cell is proposed, which uses interior vortices in layered superconducting system as information bits. In the memory cell, such vortices represents an interesting storage medium for future Josephson computers. The current state of the vortex driving is investigated. The connection between the material performance and serviceability of this memory cell is established. The results obtained show that the proposed type of vortex memory is more preferred than the one based on the use of a two-dimensional array of single-quantum vortices in a thin-film type-II superconductor.
STUDY OF PASSIVATED FILMS OF GaSb
Authors: REYES-VALDERRAMA M. I. , CORONA-ORGANICHE E. , DIAZ-REYES I. , HERRERA-PERFZ J. L. , CRUZ E. LOPEZ
Published: July 2002

Thin anodie oxides (5-10 μm) were formed on n-GaSb (100) substrates by electrochemical method under galvanostatic regime employing an aqueous solution (citric acid/hydrogen peroxide), at volume ratio of 5:1, changing the time of growth. The thickness and index of refraction, thermal diffusivity and quality of passivated films were obtained by IR reflectance spectroscopy, photoacoustic spectroscopy and finally photoluminescence spectroscopy.
EFFICIENT ALGORITHM FOR INITIALIZING AMPLITUDE DISTRIBUTION OF A QUANTUM REGISTER
Authors: ANDRECUT M. , ALI M. K.
Published: July 2002

The preparation of a quantum register in an arbitrary superposed quantum state is an important operation for quantum computation and quantum information processing. Here, we present an efficient algorithm which requires a polynomial number of elementary operations for initializing the amplitude distribution of a quantum register.
CHARACTERISATION OF CONDUCTING POLYMERS USING ION BEAM ANALYSIS
Authors: MORETTO G. L. , MARKWITZ A. , HALL S. B. , BURRELL A. K. , OFFICER D. L. , CAMPBELL W. M , COLLIS G. E.
Published: July 2002

Complex bis terthiophene porphyrin conducting polymers were used to investigate the uptake of zinc into the freebase porphyrin unit after polymerisation by acquiring depth profiles using Rutherford Backscatting Spectrometry (RBS) analysis. Issues such as the influence of the support material and extent of polymer oxidation on the dispersion of the counter ions through the polymer films are of importance. Gaining knowledge of the dispersion of counter ions provides new insights into the redox mechanisms for conductive polymers. The results were compared to those obtained from a sample where zinc was coordinated to the porphyrin prior to the polymerisation process.

Unexpectedly high concentration of both nitrogen and oxygen were found which could be due to evidence of the trapped cations from the electrolyte ( (Bu) 4 N +), and trapped water molecules, within the polymer films. The chlorine concentrations help to understand the dispersion of the perchlorate counter ion throughout the polymer films, and the combination of both RBS and Proton Induced X-ray Emission (PIXE) show that trace element impurities can be detected using ion beam analysis which other analytical techniques are unable to do.
THE Ni INFLUENCE ON THE INTERGRANULAR PROPERTIES OF BULK (Bi,Pb):2223 SUPERCONDUCTOR
Authors: POP A. V.
Published: July 2002

The effect of Ni 3+ ions on the intergranular T p temperature of the imaginary peaks of the ac susceptibility has been studied for a (Bi,Pb):2223 superconductor. The linear dependence of T p as a function of ac field amplitude agree with Muller critical state model. The Ni 3+ ions induced an increase of intergranular pinning force density. J cJ (T) dependence near T c agrees with the assumption of SNS intergrain junctions.
THEORY OF THE SEEBECK COEFFICIENT IN ALKALI AND NOBLE METALS
Authors: FUJITA SHIGEJI , HO HUNG-CHEUK , GODOY SALVADOR
Published: July 2002

A new formula for the Seebeck coefficient S is obtained: [Formula: see text], where q, n, ε F , [Formula: see text] and [Formula: see text] are, respectively, charge, carrier density, Fermi energy, density of states at ε F and volume. Seebeck (S) and Hall (R H ) coefficients in alkali metals are both negative while these coefficients in noble metals have opposite signs. This difference is shown to arise from the different shapes of the Fermi surface.
ONSAGER'S FORMULA, CONDUCTIVITY, AND POSSIBLE NEW PHASE TRANSITION
Authors: LO SHUI-YIN , LI WENCHONG
Published: July 2002

Conductivity measurements have been made for very dilute solutions of NaCl, KCl, HCl and NaOH. They obey the well-known Onsager's formula quite well at high concentration, but deviate from it at low concentration in the region of about 10-4 M. The oscillation of conductivity has also been measured for very dilute NaCl solution, where a λ-shape transition is found in the same region. This possibly indicates a phase transition due to the formation of metastable water clusters.
FAST LEARNING USING MULTILAYER PERCEPTRON NETWORKS WITH ADAPTIVE CENTROID LAYER
Authors: LEHTOKANGAS MIKKO
Published: July 2002

A hybrid neural network architecture is investigated for classification purposes. The proposed hybrid is based on the multilayer perceptron (MLP) network. In addition to the usual hidden layers the first hidden layer is selected to be an adaptive centroid layer. Each unit in this new layer incorporates a centroid vector that is located somewhere in the space spanned by the input variables. The output of these units is the Euclidean distance between the centroid vector and the inputs. The centroid layer has some resemblance to the hidden layer of the radial basis function (RBF) networks. Therefore the proposed design can be regarded as a sort of hybrid of the MLP and RBF networks. The presented benchmark experiments demonstrate that the proposed hybrid can provide significant advantages over standard MLPs in terms of fast and efficient learning, and compact network structure.
ON THE IDEMPOTENCY AND CO-IDEMPOTENCY OF THE MORPHOLOGICAL CENTER
Authors: WILD MARCEL
Published: July 2002

By a novel use of distributivity we obtain polynomial time algorithms to decide whether or not a given min–max operator (stack filter) is idempotent or not. Several properties related to idempotency can also be tested in polynomial time. In particular we apply these results to the morphological center of two operators. The main application of these results is in nonlinear image processing.
iJADE AUTHENTICATOR — AN INTELLIGENT MULTIAGENT BASED FACIAL AUTHENTICATION SYSTEM
Authors: LEE RAYMOND S. T.
Published: July 2002

In modern consumer e-shopping environments, customer authentication is a critical process for confirming the identity of the customer. Traditional authentication techniques that rely on the customers to proactively identify themselves (using various schemes) can affect the user-friendliness of the e-shopping experience, and therefore reduce the customers' preference for such facilities. In this paper, we propose an innovative intelligent multiagent-based environment, called iJADE (intelligent Java Agent Development Environment) to provide an intelligent agent-based platform in the e-commerce environment. Contemporary agent development platforms are focused on the autonomy and mobility of the agents, whereas iJADE provides an intelligent layer (known as the "conscious layer") to implement various AI (artificial intelligence) functionalities in order to produce "smart" agents. From an implementation perspective, we introduce an innovative e-shopping authentication scheme called the "iJADE Authenticator", which is an invariant face recognition system that uses intelligent mobile agents. This system can provide fully automatic, mobile and reliable user authentication. More importantly, the authentication process can be carried out without the users necessarily being aware of it. Experimental results are presented for a database of 1020 tested face images obtained under conditions of widely varying facial expressions, viewing perspectives and image sizes. An overall average correct recognition rate of over 90% is attained.
OPTIMAL CONTROL OF CHAOTIC SYSTEMS
Authors: GÓRA PAWEŁ , BOYARSKY ABRAHAM
Published: July 2002

The problem of controlling a chaotic system is treated from a long term statistical basis. Unlike the OGY targeting method that exploits individual unstable orbits, this approach is concerned with targeting the density function of an invariant probability measure. Given a point transformation T, possessing a density function f, we choose [Formula: see text], a different probability density function, to be the target. Using optimization methods, we construct a point transformation [Formula: see text], close to T, whose invariant probability density function is [Formula: see text], or close to [Formula: see text].
PIECEWISE LINEAR MODEL FOR TREE MAPS
Authors: BAILLIF MATHIEU , DE CARVALHO ANDRÉ
Published: July 2002

We generalize to tree maps the theorems of Parry and Milnor–Thurston about the semi-conjugacy of a continuous piecewise monotone map f to a continuous piecewise linear map with constant slope, equal to the exponential of the entropy of f.
FRACTALS IN AN ELECTRONIC CIRCUIT WITH BY SWITCHING INPUTS
Authors: NISHIKAWA JUN , GOHARA KAZUTOSHI
Published: July 2002

We have proposed a process of generating fractals not from the results of chaotic dynamics, but from the switching of ordinary differential equations. This paper experimentally and numerically analyzes the dynamics of an electronic circuit driven by stochastically switching inputs. The following two results are obtained. First, the dynamics is characterized by a set Γ(C) of trajectories in the cylindrical phase space, where C is a set of initial states on the Poincaré section. Γ(C) and C are attractive and unique invariant fractal sets that satisfy specific equations. The second result is that the correlation dimension of C is in inverse proportion to the interval of the switching inputs. These two findings move beyond the conventional theory based on contraction maps. It should be noted that the set C is constructed by noncontraction maps.
INVARIANT STRUCTURE OF NONLINEAR SYSTEMS WITH APPLICATION TO CHAOS CONTROL
Authors: ZHENG YUFAN , ZHANG CISHEN , YU XINGHUO
Published: July 2002

This paper studies the single-input controllable nonlinear system and explores its invariant structure in terms of internal feedback loops. The invariant structure provides a useful framework for the analysis and design of nonlinear systems. An application of the invariant structure to controlling Lorenz chaos is presented.
ON SOME NONAUTONOMOUS CHAOTIC SYSTEM ON THE PLANE
Authors: WÓJCIK KLAUDIUSZ
Published: July 2002

We prove the existence of the chaotic behavior in dynamical systems generated by some class of time periodic nonautonomous equations on the plane. We use topological methods based on the Lefschetz Fixed Point Theorem and the Ważewski Retract Theorem.
MALLEABLE SERVICES
Authors: VASUDEVAN VENU , LANDIS SEAN
Published: July 2002

Deploying distributed services over a complex network topology presents a challenge: one of mapping the objects to locations in an optimal manner. This mapping needs to be dynamic, taking current network conditions into consideration. Remapping services is manual-intensive, requires operator effort and may result in service downtime. The Mojave project described here investigates an architecture for implementing malleable (auto-configuring) services using reactive and mobile agents. In contrast to past efforts, Mojave views agents as a wrapper technology implemented over a Jini/tuplespace-based architecture. The paper describes the Mojave architecture and implementation, experiences in building an adaptive systems manager application, and benefits of the Mojave architecture for thin-client computing.
THE AUTOMORPHISMS GROUP OF THE MULTIPLICATIVE CARTAN DECOMPOSITION OF LIE ALGEBRA E8
Authors: GRISHKOV ALEXANDER N.
Published: July 2002

We construct a new basis for the exceptional simple Lie algebra L of type E8 and describe the multiplication rule in this basis. It allows to find the action of generators of automorphism group of the multiplicative Cartan decomposition of L on this basis.
QUASI PERIODIC OSCILLATIONS IN X-RAY NEUTRON STAR AND PROBES OF PERIHELION PRECESSION OF GENERAL RELATIVITY
Authors: ZHANG C. M.
Published: July 2002

We ascribe the twin kilohertz Quasi Periodic Oscillations (kHz QPOs) of X-ray spectra of Low Mass X-Ray Binaries (LMXBs) to the pseudo-Newtonian Keplerian frequency and the apogee and perigee precession frequency of the same matter in the inner disk, and ascribe 15–60 Hz QPO (HBO) to the apogee (or perigee) precession and its second harmonic frequency to both apogee and perigee precession in the outer disk boundary of the neutron star (NS) magnetosphere. The radii of the inner and outer disks are correlated each other by a factor of two is assumed. The obtained conclusions include: all QPO frequencies increase and frequency difference of twin kHz QPOs decreases with increasing the accretion rate. The obtained theoretical relations between HBO frequency and twin kHz QPOs are simlilar to the measured empirical formula. Further, the theo-retical formula to calculate the NS mass by the twin kHz QPOs is proposed, and the resultant values are in the range of 1.4 to 1.8 M⊙. QPOs from LMXBs likely provide an accurate laboratory for a strong gravitational field, by which a new method to determine the NS masses of LMXBs is suggested.
STRING-DUST IN HIGHER-DIMENSIONAL CYLINDRICALLY SYMMETRIC COSMOLOGICAL MODEL
Authors: CHAKRABORTY SUBENOY , ROY ANUSUA
Published: July 2002

We have studied string cosmology in higher-dimensional cylindrically symmetric model which is in the Kaluza–Klein spacetime. Some of the solutions show a nonsingularity of the spacetime.
SCALING OF MULTIFRACTAL MEASURES UNDER AFFINE TRANSFORMATIONS
Authors: VENEZIANO DANIELE , FURCOLO PIERLUIGI
Published: July 2002

Multifractal measures have the property of being statistically invariant under some group of space and field transformations. In general, the measures lack invariance for transformations outside this group, but we show that an important exception exists. We consider measures that are invariant under isotropic contraction and examine how their marginal distribution changes under affine space transformations. We find that, for regions that are highly elongated in one direction, the marginal distribution satisfies a multifractal scaling relation that depends on the direction of elongation. We use numerical simulation to investigate the transition range between asymptotic scaling regimes, when the regions do not have extreme elongation in any one direction. The results have practical implications on the inference of multifractal properties from observations in regions with one or more fixed dimensions.
ANALYSIS AND PROCESSING OF RECEIVED SIGNALS IN BOREHOLES
Authors: HOVEM JENS M. , DONG HEFENG , LOTSBERG ODDVAR
Published: July 2002

This study is a part of a project to develop a borehole sonar for acoustic imaging of the geological structure of the rock formation near to a deviated or horizontal borehole performed while drilling. The purpose of the sonar is to provide a direct measure of the distance and the direction to bed boundaries parallel to the borehole. This paper gives a theoretical analysis of the effect of the borehole and the drillstring on the received response on sensors positioned on the drillstring and proposes a method for processing the received signal to enable the determination of the direction of an incoming plane wave and time of arrival. In the first part of this paper, the response at any position in a fluid filled borehole is determined for an incoming plane P-wave. It is shown that the response is quite complicated and consists of several vibrating modes with resonance structure. Secondly, the paper presents how the received signals can be decomposed and the individual modes can be resolved by utilizing the orthogonal properties of the mode functions. The individual mode functions are resolved by performing a spatial Fourier transform of the sensor signals. A requirement is that the sensors are uniformly distributed around the circumference of the drillstring and that the number of sensors is at least two times the number of significant modes. It is demonstrated that the spatial and temporal characteristics of the resolved modes can then be exploited to determine the time of arrival and the angle of direction of the incoming reflected waves.
BACKSCATTERING EFFECTS IN MODULATED ELECTRON EMISSION FROM ULTRATHIN OVERLAYERS
Authors: DI BONA A. , LUCHES P. , BORGHI A. , ROSSI F. , VALERI S.
Published: July 2002

The intensity of the Auger emission from ultrathin (<2 monolayers) overlayers excited by energetic (1–5 keV) electron beams, shows an unusually large anisotropy as a function of the incidence angle. We proposed a multistep mechanism which accounts for this anisotropy, based on the electron focusing and backscattering of the beam electrons from the bulk atoms. The intensity and anisotropy of the backscattered electrons has been measured in a large energy interval and its relationship with the structure and the Auger emission from the surface layer is discussed.
A SURFACE ANOMALOUS DIFFRACTION STUDY OF THE Ni(100)(3×3)-(Cs+O) SYSTEM
Authors: NORRIS A. G. , LUCAS C. A. , McGRATH R. , SCHEDIN F. , THORNTON G. , TURNER T. S. , NORMAN D.
Published: July 2002

Alkali metal coadsorption systems represent a step along the pathway from simple model adsorbate overlayers to more technologically relevant real systems. However, such is their complexity that very few systems have been structurally determined. Here we present a surface X-ray diffraction investigation of one of these systems, Ni (100)-(3×3)- (Cs+O) . Here a structural determination is particularly challenging due to the presence of three species in the surface layers and by the size of the unit cell. As a first step, anomalous scattering has been used to determine whether there is a contribution of the nickel substrate to the fractional order diffraction intensity. Measurements of the fractional order rods at 10 eV and 200 V below the nickel K edge (8333 eV) were used to probe the nickel contribution to the fractional order rods. It was found that the intensity of the scattering was unchanged, indicating that the fractional order peaks are caused by scattering from the coadsorbates only. This shows that the nickel surface layers are not changed by the adsorption and thus sets a useful constraint on the number of possible structures.
DC-HEATING-INDUCED ANTIBAND FORMATION AND SUBSEQUENT STEP WANDERING ON Si(111) STUDIED BY IN-SITU REM
Authors: DEGAWA MASASHI , MINODA HIROKI , TANISHIRO YASUMASA , YAGI KATSUMICHI
Published: July 2002

Direct current fed through a Si crystal with (111) vicinal surfaces induces step bunching and wandering which depend on the temperature and the current direction. In the present report in-situ reflection electron microscope studies of antiband formation and the growth of step wandering are presented together with supplemental observations by scanning electron microscopy and optical microscopy. Observations were for the temperature range (about 1000–1180°C) where the step-down current induces step wandering and the step-up current induces step bunching and antiband formation and subsequent step wandering. An important role of antiband formation for step wandering in the step-up current regions is presented.
The Anastomosis of the Anterior Interosseous Artery as Vascular Augmentation in Forearm Replantation
Authors: Innocenti M. , Ceruso M. , Beltrami G. , Bufalini C.
Published: July 2002

Bony non-union and muscle ischaemic contracture are the most frequent late complications of forearm replantation. We report our experience in a case of forearm replantation, where an early restoration of arterial inflow was achieved by the anastomosis of the anterior interosseus artery (A.I.A.) immediately after bone fixation. There was no complication in this case and the functional results were particularly encouraging. The biological and practical advantages of using the A.I.A. for vascular anastomosis are described and discussed.
OSTEOCHONDROMA PREVENTING CLOSED REDUCTION OF A PROXIMAL INTERPHALANGEAL DISLOCATION OF THE LITTLE FINGER
Authors: Horiuchi K. , Yamauchi K. , Tanaka M.
Published: July 2002

We present a case of a 21-year-old male patient who developed an osteochondroma at the neck of the proximal phalanx of the left little finger, which interfered with reduction of a dorsally dislocated PIP joint. This is the first such case report in the literature. At the time of surgery, we excised the osteochondroma and reconstructed the collateral ligament that produced locking of the PIP joint. This treatment brought a quick and essentially complete recovery of the PIP joint function. At 3 years follow-up in the affected digit, the patient has no limitations in daily activities.
ON THE RELATION OF THE SQUARE OF WHITE NOISE AND THE FINITE DIFFERENCE ALGEBRA
Authors: ACCARDI LUIGI , SKEIDE MICHAEL
Published: July 2002

The algebra of square of white noise1 contains a subalgebra generated by elements fulfilling the relations of Feinsilver's finite difference algebra.6 Moreover, Boukas' representation space3 is the same as the representation space of the algebra of square of white noise discovered in Ref. 2. In other words, Boukas' representation extends to a representation of the algebra of square of white noise.
Factors Affecting Foreign Direct Investment — with an Analysis of the Disparity between the Coastal and Western Regions of China
Authors: Cheng Hsiao , Gastañaga Victor
Published: July 2002

We review the literature on foreign direct investment (FDI) and provide an empirical analysis of factors affecting FDI. Conjectures of the disparity of FDI between the coastal and western regions of China and policy recommendations are also made.
A NON-COOPERATIVE BARGAINING PROCEDURE GENERALISING THE KALAI-SMORODINSKY BARGAINING SOLUTION TO NTU GAMES
Authors: BERGANTIÑOS GUSTAVO , CASAS-MÉNDEZ BALBINA , VÁZQUEZ-BRAGE MARGARITA
Published: July 2002

We present a new NTU value, which generalises the Kalai-Smorodinsky bargaining solution to NTU games using three approaches. In the first section, we define the new NTU value as the only efficient point in the segment defined by an upper and a lower bound. Next, we define a bargaining procedure and prove that this procedure leads to a single, subgame perfect equilibrium payoff vector, which coincides with the new NTU value. Finally, we characterise the new value using several properties.
A CO-MARGINALISTIC CONTRIBUTION VALUE FOR SET GAMES
Authors: SUN HAO , ZHANG SHENGGUI , LI XUELIANG , DRIESSEN THEO , HOEDE CORNELIS
Published: July 2002

In this paper, a new value for set games, named co-marginalistic contribution value, is characterised by the standard axioms of global efficiency and equal treatment property, and another axiom of co-coalitional marginalistic monotonicity, which is a modification of the axiom of monotonicity. The co-marginalistic contribution value for set games is analogous to the solidarity value for n-person TU-games. Since the co-marginalistic contribution value does not satisfy the axiom of additivity, the proof of the characterisation is much different from that for TU-games.
EXISTENCE OF MINIMAL H-BUBBLES
Authors: CALDIROLI PAOLO , MUSINA ROBERTA
Published: July 2002

Given a function H ∈ C1 (ℝ3) asymptotic to a constant at infinity, we investigate the existence of H-bubbles, i.e., nontrivial, conformal surfaces parametrized by the sphere, with mean curvature H. Under some global hypotheses we prove the existence of H-bubbles with minimal energy.
APPLICATIONS OF MICROWAVE RADIATION IN MEDICINE
Authors: YANG WEN-JEI , MOCHIZUKI SADANARI , YANG PAUL P.-T.
Published: July 2002

This paper presents major medical applications of microwave radiation in therapy and diagnostics of disorders of thermoregulation, especially hyperthermia and thermography. Microwave thermography is a thermal imaging system produced by self-emission, using emissivity differences to extend our vision beyond the shortwave red. Human tissues are partially transparent to microwaves, thus it is possible to detect the microwave of subcutaneous tissues in thermography, and to allow microwave energy penetration through subcutaneous tissues for deep-tissue heating in hyperthermia. The physics of microwave thermography together with the microwave properties and emission of body tissues are introduced. It is followed by reviews of the literature pertinent to microwave hyperthermia in therapy and treatment. Recent development in this field is briefly discussed.
Authentication in the Taos operating system
Authors: Wobber Edward , Abadi Martín , Burrows Michael , Lampson Butler
Published: July 2002

We describe a design for security in a distributed system and its implementation. In our design, applications gain access to security services through a narrow interface. This interface provides a notion of identity that includes simple principals, groups, roles, and delegations. A new operating system component manages principals, credentials, and secure channels. It checks credentials according to the formal rules of a logic of authentication. Our implementation is efficient enough to support a substantial user community.
A concurrency analysis tool suite for Ada programs
Authors: Young Michal , Taylor Richard N. , Levine David L. , Nies Kari A. , Brodbeck Debra
Published: July 2002

Cats (Concurrency Analysis Tool Suite) is designed to satisfy several criteria: it must analyze implementation-level Ada source code and check user-specified conditions associated with program source code; it must be modularized in a fashion that supports flexible composition with other tool components, including integration with a variety of testing and analysis techniques; and its performance and capacity must be sufficient for analysis of real application programs. Meeting these objectives together is significantly more difficult than meeting any of them alone. We describe the design and rationale of Cats and report experience with an implementation. The issues addressed here are primarily practical concerns for modularizing and integrating tools for analysis of actual source programs. We also report successful application of Cats to major subsystems of a (nontoy) highly concurrent user interface system.
Parametricity and local variables
Authors: O'Hearn P. W. , Tennent R. D.
Published: July 2002

We propose that the phenomenon of local state may be understood in terms of Strachey's concept of parametric (i.e., uniform) polymorphism. The intuitive basis for our proposal is the following analogy: a non-local procedure is independent of locally-declared variables in the same way that a parametrically polymorphic function is independent of types to which it is instantiated.

A connection between parametricity and representational abstraction was first suggested by J.C. Reynolds. Reynolds used logical relations to formalize this connection in languages with type variables and user-defined types. We use relational parametricity to construct a model for an Algol-like language in which interactions between local and non-local entities satisfy certain relational criteria. Reasoning about local variables essentially involved proving properties of polymorphic functions. The new model supports straightforward validations of all the test equivalences that have been proposed in the literature for local-variable semantics, and encompasses standard methods of reasoning about data representations. It is not known whether our techniques yield fully abstract semantics. A model based on partial equivalence relations on the natural numbers is also briefly examined.
A versatile data structure for edge-oriented graph algorithms
Authors: Ebert Jürgen
Published: July 2002

An abstract graph module that allows for easy and secure programming of a great number of graph algorithms is implemented by symmetrically stored forward and backward adjacency lists, thus supporting edge-oriented traversals of general directed and undirected graphs.
Monte Carlo techniques for direct lighting calculations
Authors: Shirley Peter , Wang Changyaw , Zimmerman Kurt
Published: July 2002

In a distributed ray tracer, the sampling strategy is the crucial part of the direct lighting calculation. Monte Carlo integration with importance sampling is used to carry out this calculation. Importance sampling involves the design of integrand-specific probability density functions that are used to generate sample points for the numerical quadrature. Probability density functions are presented that aid in the direct lighting calculation from luminaires of various simple shapes. A method for defining a probability density function over a set of luminaires is presented that allows the direct lighting calculation to be carried out with a number of sample points that is independent of the number of luminaires.
An approach to 3D pose determination
Authors: Ezquerra Norberto , Mullick Rakesh
Published: July 2002

The orientation, or pose, of an object is a fundamental property that helps to define the geometrical relationship between the object and its environment. In addition, knowledge of object orientation can also facilitate interpretive and decision-making tasks in a variety of practical domains, including industrial, meteorological, and medical applications. Determining object pose, however, remains an open research question in the fields of graphics and visualization. This article describes a novel yet intuitively simple approach, which we call topological goniometry, to directly determine the pose of a three-dimensional object from 3D data. The topology of interest is that of two-sided surfaces in a three-manifold, and includes objects whose shaped are unaffected by elastic transformations. Algorithmically, topological goniometry is composed of the following major steps. The first analyzes the global topology in order to generate a distribution of 3D coordinate triplets in the proximity of the desired pose axis. Using this set of 3D points, that second step then invokes a “3D Walk” algorithm that considers the local topology to produce a generalized curve representing an estimate of the object's axis of pose. The resultant pose axis is thus not constrained to lie along a straight line but can be generalized 3D curve. The methods are illustrated with a variety of synthetically created models that exhibit duct-like shapes, and are further tested by introducting noise as well as deformations to these models. The approach is also applied to a number of real discrete data obtained from meteorological and medical domains. The results suggest that the appproach is applicable to both real and synthetic datasets and is shown to be robust, computationally efficient, and applicable to a variety of problems. The approach can incorporate context- or application-dependent information about the object of interest by using a set of constraints that guide the process of orientation determination. This article describes the approach, its implementation, and the results obtained with numerous applications.
Applying formal methods to semantic-based decomposition of transactions
Authors: Ammann Paul , Jajodia Sushil , Ray Indrakshi
Published: July 2002

In some database applications the traditional approach of seerializability, in which transactions appear to execute atomically and in isolation on a consistent database state, fails to satisfy performance requirements. Although many researchers have investigated the process of decomposing transactions into steps to increase concurrency, such research typically focuses on providing algorithms necessary to implement a decomposition supplied by the database application developer and pays relatively little attention to what constitutess a desirable decomposition or how the developer should obtain one. We focus onthe decomposition itself. A decomposition generates proof obligations whose descharge ensures desirable properties with respect to the original collection of transactions. We introduce the notion of semantic histories to formulate and prove the necessary properties, and the notion of successor sets to describe efficiently the correct interleavings of steps. The successor set constraints use information about conflicts between steps so as to take full advantage of conflict serializability at the level of steps. We propose a mechanism based on two-phase locking to generate correct stepwise serializable histories.
Color image quantization by minimizing the maximum intercluster distance
Authors: Xiang Zhigang
Published: July 2002

One of the numerical criteria for color image quantization is to minimize the maximum discrepancy between original pixel colors and the corresponding quantized colors. This is typically carried out by first grouping color points into tight clusters and then finding a representative for each cluster. In this article we show that getting the smallest clusters under a formal notion of minimizing the maximum intercluster distance does not guarantee an optimal solution for the quantization criterion. Nevertheless our use of an efficient clustering algorithm by Teofilo F. Gonzalez, which is optimal with respect to the approximation bound of the clustering problem, has resulted in a fast and effective quantizer. This new quantizer is highly competitive and excels when quantization errors need to be well capped and when the performance of other quantizers may be hindered by such factors as low number of quantized colors or unfavorable pixel population distribution. Both computer-synthesized and photographic images are used in experimental comparison with several existing quantization methods.