bluuebunny/crossref_metadata_2025 huggingface dataset:
ION LASER THEORY
Authors: SHAPIRO D.
Published: October 2004

Ion lasers, especially argon, are the most powerful sources of visible and near UV continuous coherent radiation. The active medium of lasers is low-temperature plasma. They are familiar to scientists and engineers from the 70’s. However, a series of physical effects remained unclear and there was a barrier to enhancing the power and improving the quality of the output radiation. The theory of ion lasers is developed at the interface between plasma physics and quantum optics. This paper covers the solution of some of these physical problems, particularly, the high-current regime of gas discharge and the quantum kinetics of ionic collisions. The high-current multi-component discharge is important for intense generation in the ultraviolet spectrum. The ionic scattering leads to the Lamb dip broadening in the single-frequency laser and increases its output.
TRANSFERRING ELECTRONS ONE BY ONE IN SINGLE ELECTRON DEVICES WITH LONG ARRAYS OF TUNNEL JUNCTIONS
Authors: HU G.Y. , O’CONNELL R.F. , KANG YOUNG BONG , RYU JAI YON
Published: October 2004

We review recent theoretical work on an analytical approach to the charge dynamics of electron tunneling in single electron devices consisting of long arrays with equal stray capacitances and equal junction capacitances. Our approach to the problem has two basic steps. First, we find the exact solution for the potential profiles and the associated Gibbs free energy, based on a technique for diagonalizing a particular type of a tridiagonal matrix equation. Second, we study the change of the Gibbs free energy arising from single charge transfer. The method has been applied to one-dimensional long arrays, single electron traps, and single electron turnstiles, and the results are compared with that of the existing experiments. We point out the advantages of our method vis-à-vis other approaches used in the literature.
RADIAL MATRIX ELEMENTS WITH DIRAC’S FUNCTIONS IN THE THEORY OF FINE AND HYPERFINE STRUCTURES OF HYDROGEN-LIKE SYSTEMS
Authors: TARASOV V.F.
Published: October 2004

Investigating the effects of fine and hyperfine structures of hydrogen spectrum there arises practical necessity to evaluate the different matrix elements with Dirac’s radial functions f and g; usually such matrix elements being evaluted approximately.

The article deals with the study of relativistic matrix elements by a new method, i.e. with the help of Appell’s hypergeometrical functions F2(x, y) and their new properties. Such approach allows: (1) to get exact analytical expressions for these matrix elements by means of Appell’s F2 (and Clausen’s 3F2) functions; (2) to reveal “latent” symmetry of diagonal matrix elements of such types as 〈rk〉njl and 〈g|rk|f〉njl with respect to points k0=–3/2 and k0=–1/2, respectively, the above symmetry is connected with the property of Appell’s function F2(1, 1) mirror-like symmetry; (3) to prove that the diagonal and off-diagonal matrix elements in a “pole-domain” of Euler’s gamma-function are given exactly analytically by means of “nonorientable” series of type Ḟ2(x, y). The examples for the evaluation of diagonal matrix elements for the K- and L-shells and also of dipole matrix elements for Lyman’s series are obtained.
EXACT SOLUTIONS FOR QUANTUM THREE WAVE INTERACTION SYSTEM
Authors: ZHAO HONGWEI , LIU WU-MING , WANG YUPENG , PU FU-CHO
Published: October 2004

The exact eigenstates of the Hamiltonian for a quantum three wave interaction system are constructed by using the Bethe ansatz. The Bethe-ansatz equations are obtained from the periodic boundary conditions.
QUANTUM VARIATIONAL PRINCIPLE OF IRREVERSIBLE PROCESSES IN A MAGNETIC FIELD
Authors: HATTORI MASUMI , NAKANO HUZIO
Published: October 2004

Quantum variational principle of irreversible processes is generalized to the systems under the uniform magnetic field. For the electron transport in impurity potentials as a typical example, contractions of the density matrix are performed without any approximation in two steps; first the off-diagonal part of the density matrix is eliminated and subsequently the even part with respect to time reversal. In consequence the maximum principle is derived for the odd part of the diagonal elements of the density matrix. This means the contraction of the density matrix brings about irreversibility. The variational principle is shown to be closely related to that for the conventional Boltzmann–Bloch equation and is regarded as its fundamental version. The dependences of the density matrix on the magnetic field and wave number are discussed.
CORE STRUCTURE AND ENERGIES OF MULTIPLE-n QUANTUM VORTICES
Authors: BEN-YA'ACOV URI
Published: October 2004

Quantum vortices with a multiple winding number (n ≠ ±1) are interpretable as metastable states of | n | elementary vortices. The information on the structure of these metastable states is contained in the amplitude of the complex scalar field ϕ (x) which describes the medium in which the vortices appear. A direct measure of this structure is given by the core radius associated with the vortex that corresponds to the metastable state. Several algorithms are suggested for the calculation of the core radius of vortices, and other radii related to the vortex energy, from the knowledge of the amplitude | ϕ (x) |. These radii are numerically computed as functions of the winding number n of the vortices for nine different test models. All these sets are found to be linear in n to a very high accuracy in all the test models. Linear fits are calculated, with some parameters found to be model independent. General conclusions concerning the dependence of the vortex energy on the winding number are also obtained.
EFFECT OF DIELECTRIC PROPERTY OF HYDROUS DISPERSOID ON ELECTRORHEOLOGY
Authors: KAWAI Akiko , UCHIDA Kunio , KAMIYA Kunio , GOTOH Akihiro , YODA Satoshi , URABE Kei , IKAZAKI Fumikazu
Published: October 2004

The effect of the dielectric property was investigated of titania and microcrystalline cellulose particles dispersed in a silicon oil on Electrorheology(ER). A commom understanding of the mechanism of ER is the electrical interaction by the interfacial polarization of dispersed particles. Block et al. reported the relaxation frequency of ER fluids, i. e. the rate of polarization, was very important to have an appreciable ER effect.

We found that the free water on the cellulose and the titania particles dispersed in the silicon oil, which is respectively dehydrated below the temperature of ca. 110 and 300 degree centigrade, was necessary for an appreciable ER effect. The relation was measured between the water content and the dielectric properties such as dielectric constant ε ’ and dielectric loss factor ε ", as the water adsorbed on the particles was estimated to alter the dielectric properties of the ER fluid. Both the dielectric constant and the relaxation frequency, which is defined by the applied frequency for a peak of the dielectric loss factor, increased with the increase of the water content The relation was discussed between the ER effect and the dielectric properties.
Closed Loop Controlled ER-Actuator
Authors: WOLFF C.
Published: October 2004

The results of the investigation regarding the suitability of ERF when applied in hydraulics have shown so far that constructing electrorheological flow resistors for the control of pressure and volume flow is possible in principle. One of the main advantages when using the ER-technology in hydraulic systems can be seen in the high reaction rate of the ER-effect. The investigations presented in this article document the dynamic qualities of ER-fluids by means of a practical exploitation for the control of a cylinder actuator. Due to the particular possibilities for design of ER-control resistors a compact cylinder has resulted which differs considerably from traditional cylinder actuators in its construction and dynamic behaviour.
DIELECTRIC EVIDENCE FOR THE MATERIAL DESIGN OF ER FLUIDS
Authors: Hao Tian , Xu Yuanze
Published: October 2004

The dielectric and electrorheological measurements of anhydrous ER fluids based upon oxidized polyacrylonitrile and zeolite under AC electric field are described It was found that the yield strength was not only determined by dielectric constant of suspensions, but also by dielectric loss. The formulation based on Wagner model, which describes the polarization of heterogeneous dielectrics, was employed to predict the yield stress as a function of electric frequency. The good agreement between experimental and theoretical predictions indicated that conductivity of the dispersed particle and the dielectric constants of ER suspension are decisive factors in the design of ER fluids. The way of material design is discussed concerning working frequency, rate and temperature ranges
ROTATION OF THE AXISIMMETRIC DIELECTRIC BODIES (DEB) IN ELECTRORHEOLOGICAL SUSPENSIONS (ERS)
Authors: SHULMAN ZINOVIY P. , NOSOV VALERIY
Published: October 2004

Consideration is given to rotation of nonconducting bodies in electrorheological suspensions. Experimental data are presented describing the effect of an electric field on the rotation speed as well as on rheological and electrophysical properties of ERS. The dependence of speed on temperature and the rotor geometry is considered in some detail. Two examples of engineering applications are presented.
An Electrostatic Stepper Motor
Authors: Partington E.C. , Wong Edward Chun Kay , Bullough W.A.
Published: October 2004

This paper describes a new concept in pulse controlled motor and precision linear actuator techniques. Piezo translators [PZT] employed to provide reciprocating primary motion are connected to a load via a controllable electrorheological fluid [ERF] clutch to form a programmable speed and step-width drive. Ideal considerations are used to quantify the limiting potential of the drive and details are given of its development and progress.
MATERIALS FOR ER FLUIDS
Authors: BLOODWORTH ROBERT , WENDT ECKHARD
Published: October 2004

Recent improvements in the physical understanding of ER fluids have led to the rational design of new ER materials with improved properties. This paper gives an overview of several recent developments in the formulation of ER fluids, concentrating on new particulate phases for ER dispersions. Examples of homogeneous ER fluids are also discussed. The trend leading to designed ER dispersions is demonstrated by a new class of electrorheological fluids based on non-aqueous polyurethane dispersions. The fluids exhibit an attractive combination of properties: low viscosity, high ER effect, and low conductivity. The dispersed phase consists of a specially developed polyurethane elastomer which solvates and stabilizes metal salts. The polymer network density influences the mobility of the dissolved ions, allowing a surprising degree of control over the ER effect. Properties such as the field strength dependence of the ER-effect, switching response, and conductivity of these fluids correlate directly with changes in the polymer structure. Electrorheological measurements in a couette viscometer (shear-mode) and in a model shock absorber (flow-mode) using a commercial polyurethane-based fluid show that the ER effect is also dependent upon the shearing geometry.
STEADY AND TRANSIENT RESPONSES OF ELECTRORHEOLOGICAL SUSPENSION PASSING THROUGH A RECTANGULAR CHANNEL
Authors: NAKANO Masami , AIZAWA Ryuji , ASAKO Yoshinobu
Published: October 2004

The steady and transient responses of ER effect of ER fluids containing sulfonated polymer particles, passing through a rectangular channel between two fixed parallel electrodes, were investigated by ensuring pressure drops across the channel in which the flow established a Poiseuille flow geometry. Effects of the types and the strength of applied electric field and the mean flow velocity on the steady response were clarified, and compared with those in a Couette flow geometry using a rotary rheometer in order to investigate the dependence of ER effects on the flow geometry. As the mean flow velocity increased, the yield stress decreased exponentially under DC voltage, while, in the case of AC voltage, gradually increased and reached a peak level and decreased thereafter. Contrastively, the yield stress measured by the rotary rheometer decreased suddenly at low shear rate, and reached almost constant level. That is, the measured yield stress depends on the flow geometry and the type of applied electric field. The measured pressure response to a step input voltage can be approximated by a first order response, and the rising time constant of ER effect depend on the compositions of ER fluids and range from 5 to 40 msec.
STRUCTURE-SENSITIVE LIQUID-FLOWING MEDIA BASED ON POLYVINYL ALCOHOL COMPOUNDS WITH CELLULOSE ESTERS
Authors: LAZAREVA T.G. , VASHUK E.V.
Published: October 2004

The class of structure-sensitive liquid-flowing media based on polyvinyl alcohol (PVA) compounds with water-soluble cellulose esters (carboxymethylcellulose, Na-CMC, methylcellulose, MC) have been investigated. PVA may be used as an excellent structure-sensitive matrix for films and gels. Introduction of active additives allows for the formation of liquids whose structures changes under the action of external fields. Introduction of additives, especially of Na-CMC and MC into PVA in the range of certain concentrations leads to the formation of the complexes of PVA with the active molecules linked by hydrogen bonds. Besides, due to the formation of macromolecular associates, a definitely ordered structure of the solution develops. Such changes in the structure of a solution result in abnormal properties, viz. rheological (characteristic flow curves), electrophysical and optical properties in the range of certain concentrations and temperatures. These fluids may be recommended for the formation of electric field-controlled anisotropic films and fibers as well as sensors and measuring elements sensitive to external fields.
TOWARDS UNDERSTANDING ER FLUIDS USING SALS/RHEOMETRY
Authors: Crosby Bryan J. , McLeish Tom , Block Harry
Published: October 2004

This paper details work in Cranfield and Leeds Universities of making a stock of transparent ER fluids, which could later be utilised in a new optical electro rheometer (OER) to be assembled at Leeds University.

Two basic routes were attempted. One was to use glass microspheres and the other was to use polymer spheres. In order to increase the strength of the ER effect, it was necessary to increase the volume loading while still maintaining sufficient transmission (about 75% over 2 mm). It was found to be possible to increase the ER effect quite substantially in some instances, and in others it was possible to get a near perfect refractive index match. It was not possible to combine both requirements in one fluid such that a high static yield stress was apparent in a transparent ER fluid. However one fluid was made which gave acceptable diffraction losses at high volume fractions, remained in suspension for extended periods and provide about 700 Pa yield stress at 4kV/mm and about 30% volume fraction viz: untreated poly(ethylene vinyl acetate) microspheres in Cereclor/bromonaphthalene/polystyrene solution.

The OER being assembled at Leeds University is intended to record small angle light scattering (SALS) profiles, electrical and mechanical properties of ER fluids simultaneously. The OER is based around a DSR 500 machine purchased from Rheometric Scientific with quartz tools coated with transparent indium tin oxide(ITO), which is capable of measuring both steady state (DC) and oscillatory (AC) material parameters.
NUMERICAL STUDY OF THE RESPONSE TIME OF ER SUSPENSIONS
Authors: TAKIMOTO JUN-ICHI , MINAGAWA KEIJI , KOYAMA KIYOHITO
Published: October 2004

Transient response of model ER suspensions to step-wise electric field under steady shear flow is studied by numerical simulations. The electrically induced stress increases almost linearly with time up to the steady-state value, and this increase directly reflects the growth of the chain-like clusters of the dispersed particles. As the shear rate increases, the response becomes faster since the growth rate of the clusters increases and the steady-state length of the clusters decreases. The response also becomes faster by increasing the particle density or electric field, but the dependence on the field strength is rather weak.
PHASE SEPARATION AND TURBIDITY OF ELECTRORHEOLOGICAL FLUIDS
Authors: CUTILLAS S. , MEUNIER A. , LEMAIRE E. , BOSSIS G. , PERSELLO J.
Published: October 2004

The turbidity of a suspension of silica particles in a silicone oil is studied in the presence of an electric field. We present experimental results which show a very strong attenuation of a laser beam when the electric field is switched on. We give a theoretical interpretation of these results with the help of a Rayleigh Gans Debye theory applied to cylinders. This model allows us to obtain the average length of the aggregates as a function of the coupling parameter λ, which is me ratio of the electrostatic energy to kT. These results agree with a theoretical prediction and also with the results of Monte-Carlo simulations. The kinetics of the beginning of field induced aggregation can be obtained from the change of the turbidity with time after the application of a voltage step.
DEFORMATION AND RUPTURE MECHANISMS OF ER AND MR FLUIDS
Authors: Lemaire E. , Bossis G. , Volkova O.
Published: October 2004

In this paper, we discuss the different modelisations of the rupture of aggregates in ER or MR fluids. In particular, we show that microstructural models which take into account the separation between the particles inside tha aggregates give predictions very different from those based on a continuum approach. Some experimental results help us to discuss the reliability of each approach.. Creep measurements were made on TiO2 particles dispersed in silicon oil. They give information on the critical deformation at which the aggregates break. An experimental model consisting of millimetric steel spheres in a magnetic field allows us to understand the different possible mechanisms of rupture.
ELECTRORHEOLOGICAL NORMAL STRESS MEASUREMENTS OF POLYMER SOLUTIONS AND SUSPENSIONS
Authors: MINAGAWA KEIJI , KIMURA HIROSHI , TAKIMOTO JUN-ICHI , KOYAMA KIYOHITO
Published: October 2004

Normal stress measurement under an electric field is demonstrated as a new method of evaluating ER effects. The measurement was applied to liquid crystalline polymers, low molecular-weight liquid crystals, polymer suspension, and aluminum suspension. The normal stress of the liquid crystalline polymers drastically increased under an electric field at high shear rate, which suggests existence of an elastic network structure of the polymer chains. The normal stress of the suspensions also changed in the field, indicating that interaction of particles results in an increase of both shear stress and normal stress. These changes of the normal stress give additional information which is helpful for characterizing ER effects.
PRACTICE-RELEVANT ASPECTS OF CONSTRUCTING ER FLUID ACTUATORS
Authors: Janocha H. , Rech B. , Bölter R.
Published: October 2004

The flow resistance of electrorheological fluids (ER fluids) can be controlled by applying electric fields. Thus, ER fluids are suitable for the application in actuators, using high-voltage sources for the generation of the field. The behaviour of an ER fluid actuator not only depends on the properties of the individual actuator components (ER fluid, energy transducer and energy source) but especially on their combined efforts as a system. Based on a possible scheme for the design of ER fluid actuators, this paper presents important practice-relevant aspects of a systematic actuator construction. Here the behaviour of a commercial ER suspension is examined and compared to a homogeneous ER fluid without yield point using a rotational viscometer and a flow-mode damper realized at the Laboratory of Process Automation (LPA) of the University of Saarland.
TEMPERATURE EFFECTS OF DIELECTRIC PROPERTIES OF ER FLUIDS
Authors: QIU Z.Y. , HU L. , LIU M.W. , BAO H.X. , JIANG Y.G. , ZHOU L.W. , TANG Y. , GAO Z. , SUN M. , KOROBKO E.V.
Published: October 2004

Under the consideration of the role that energy transfer and dissipation play in ER effect, an improved theory frame for ER effects, polarization-dissipation-structure-rheology, is suggested. The theory frame is substantiated by the basic physical laws and certain critical experimental facts. The dielectric response of a diatomite ER fluid to temperature is measured in the temperature range of 140 K to 400 K. By comparison of the DC conductivity with the AC effective conductivity of the sample, we found that the AC dielectric loss consists of two parts. One part comes from the DC conductivity, the other from the response of the bound charges in scope of particle to AC field. It is suggested that the response of bound charges is very important to ER effects. Besides, the effect of temperature on shear stress is measured, and interpreted based on the dielectric measurements. The source of two loss peaks in the curve of the dielectric loss versus temperature is not clear.
ERF Based Precision Linear Drive System
Authors: Tönshoff Hans Kurt , Stegmann Axel
Published: October 2004

The design of clutches using electrorheological fluids (ERF) or magnetorheological suspensions (MRS) offers a new approach to precision linear drive systems based on the ‘inch-worm’ principle. This principle needs two clutches or controllable clamps and one (or more) elements to vary the distance between these clamps. To perform a caterpillar-like motion the actuators are controlled in a cyclic mode. This paper presents design elements, system structure and first results of motion performance of a prototype drive system.

The presented linear drive combines the high resolution of piezo actuators, the unlimited travel of the ‘inch-worm’ principle and the clutch effect of ERF without a substantial mechanical excitation. The motion of the two clamps is controlled to move a stage in point to point mode or to follow a given velocity profile. Using two piezo actuators the stage can move continuously. Pre-loaded piezo actuators control the distances between the two clamps and the central slide. Each ERF clamp is designed as a set of thin parallel steel plate electrodes which interlock with a set of ground plates. Drive force limits are given by the maximum yield force of the clamps as well as by the relation of the actuator expansion and the ERF/MRS shear stiffness in “solid” mode.
CONDUCTIVITY AND FORCE BETWEEN PARTICLES IN A MODEL ELECTRORHEOLOGICAL FLUID I: CONDUCTIVITY
Authors: WU C.W. , CHEN Y. , TANG X. , CONRAD H.
Published: October 2004

The conductivity of silicone oil with various water contents and that of a single-row chain of glass beads in silicone oil were determined as a function of electric field and spacing between the particles produced by tensile and shear strain. The conductivity of the silicone oil depended sensitively on its water content; that of the chain was three orders of magnitude greater than the silicone oil alone, but decreased rapidly with separation of the particles. The conductivity of the water film on the glass bead surface and the electric field enhancement in the oil gap between the beads were derived from the data. The measured current density along a chain of particles was in accord with that predicted by a conductivity model for electrorheological response. At large strains the separation of the beads in a chain became localized between one set of adjacent beads and they oscillated back-and-forth in the gap, leading ultimately to rupture of the chain with increased strain.
THE TIME RESPONSE OF AN ELECTRO-RHEOLOGICAL FLUID IN A HYDRODYNAMIC FILM
Authors: LEEK T.H. , LINGARD S. , BULLOUGH W.A. , ATKIN R.J.
Published: October 2004

The work is a practical investigation of an electro-rheological fluid in a hydrodynamic film using a Rayleigh step bearing in which a step electric field is applied across the fluid film. A number of different bearings are used, and all data presented is for the repeatable condition of zero net flow rate. Earlier work on steady state conditions is extended to high speed data logging of the pressure generation response to DC step excitations of various magnitudes
EXACT SOLUTION OF AN IRREVERSIBLE ONE-DIMENSIONAL MODEL WITH FULLY BIASED SPIN EXCHANGES
Authors: CADILHE ANTÓNIO M.R. , PRIVMAN VLADIMIR
Published: October 2004

We introduce a model with conserved dynamics, where nearest neighbor pairs of spins ↑↓ (↓↑) can exchange to assume the configuration ↓↑ (↑↓), with rate β(α), through energy decreasing moves only. We report exact solution for the case when one of the rates, α or β, is zero. The irreversibility of such zero-temperature dynamics results in strong dependence on the initial conditions. Domain wall arguments suggest that for more general, finite-temperature models with steady states the dynamical critical exponent for the anisotropic spin exchange is different from the isotropic value.
INTEGRABLE SYSTEMS ON OPEN CHAINS WITH QUANTUM SUPERSYMMETRY
Authors: LINKS J.R. , GOULD M.D.
Published: October 2004

It is demonstrated how one may derive quantum supersymmetric integrable models on an open chain corresponding to (affinizable) irreducible representations of a quantum superalgebra. A new procedure for constructing the transfer matrix is obtained and an expression for the Hamiltonian is given. Applications to Uq(gl(m|n)) invariant systems are discussed in detail. As examples, the q-analogues of several known integrable correlated electron models are presented.
ELECTRON SPECTROSCOPIC STUDIES OF MONOLAYER HEXAGONAL BORON NITRIDE PHYSISORBED ON METAL SURFACES
Authors: NAGASHIMA A. , TEJIMA N. , GAMOU Y. , KAWAI T. , TERAI M. , WAKABAYASHI M. , OSHIMA C.
Published: October 2004

The electronic properties of single-crystalline films of monolayer hexagonal boron nitride (h-BN) formed on Ni(111), Pd(111), and Pt(111) are reviewed. From the comparison of the present data with those for the rare-gas solids on metal surfaces, the interaction between the BN film and the metal substrate has been assigned to be physisorption. The valence- and conduction-band structures of the monolayer h-BN are almost independent of the substrate. The energy bands and core-levels in the BN film align with respect to the vacuum level, not to the Fermi level. In accord with these ground-state properties of the BN/metal system, the observed excitation energies for interband transitions change from one substrate to the other depending on the work function.
THREE GENERALIZED MATRIX ENSEMBLES: A REVIEW
Authors: SHAPIRO B.
Published: October 2004

The standard Gaussian matrix ensembles are known for their robustness, in the sense that their level statistics is representative of a large class of matrix models. It is possible, however, to define generalized ensembles which are able to “escape” the Gaussian fixed point and to exhibit statistics radically different from the Wigner-Dyson statistics of the standard ensembles. Such generalized ensembles contain a parameter which is allowed to change with the matrix size N. Depending on the rate of change, one obtains three distinct limiting statistics: the Wigner-Dyson statistics, the Poisson statistics of uncorrelated levels or a new intermediate statistics (the “non-trivial” fixed point). The present review discusses three examples of such generalized ensembles.
SAMPLE DEPENDENCE OF THE DENSITY OF STATES IN HETEROJUNCTIONS IN STRONG MAGNETIC FIELDS
Authors: XU W.
Published: October 2004

A detailed theoretical study of the sample dependence of the Density of States (DOS) in a strong and transverse magnetic field is presented for AlGaAs/GaAs heterojunctions and for low-temepratures. The DOS is calculated self-consistently by including electron interactions with background and remote impurities and with deformation-potential and piezoelectric acoustic-phonons. The Landau-level (LL) mixing and the energy shift are taken into account. A significant background DOS between different LL’s results from remote-impurity scattering, and it can be observed for a heterojunction sample with: (1) a relatively low-mobility; (2) the low background impurity concentration; (3) an intermediate spacer distance; and (4) a large spin g-factor. The background DOS decreases with increasing magnetic field and/or electron energy. Applying the self-consistent DOS to the calculation of the thermodynamic quantities such as specific heat, a very good agreement with the experimental results is found.
AN EXACTLY SOLVABLE ONE-DIMENSIONAL MODEL OF FERMIONS WITH CORRELATED HOPPING
Authors: KARNAUKHOV IGOR N.
Published: October 2004

A new solution of supersymmetric model of electrons with correlated hopping which generalizes those obtained earlier is formulated. The model is solved in one dimension by the Bethe ansatz. The ground state energy is calculated, and the critical exponents describing the decrease of the correlation functions on long distance are derived.
INTEGRABLE SU(m|n) SUPERSYMMETRIC ELECTRONIC MODELS OF STRONG CORRELATIONS
Authors: LIU JAMES T. , WANG D.F.
Published: October 2004

We consider the SU (m|n) supersymmetric generalization of the one-dimensional SU (2|2) symmetric extended Hubbard model of 1/r2 interaction. This model, defined on a lattice, is part of a large family of integrable one-dimensional multicomponent systems with long range interactions. We study both uniform and nonuniform lattices and present the ground state wavefunctions and energy spectra of these models. In both cases the spectrum is highly degenerate, with the SU (m|n) supersymmetry explaining most of the degeneracies.
GAUGE THEORY FOR A DOPED ANTIFERROMAGNET IN A ROTATING REFERENCE-FRAME
Authors: KÜBERT CHRISTIAN , MURAMATSU ALEJANDRO
Published: October 2004

We study the consequences of hole-doping in a two-dimensional spin- ½ quantum antiferromagnet. The analysis of a U(1) gauge theory that describes the system in a rotating reference-frame, where the spin-quantization axis of the fermions follow the local order-parameter of the antiferromagnet, leads to a quantitative description of the transition from a Néel ordered to a quantum disordered (QD) spin-liquid phase. Furthermore, it is shown that the spontaneously generated gap in the spin-wave excitation spectrum defines a new energy scale, which determines the strength of an attractive long-range interaction between magnetic and fermionic excitations. The possible bound-states are singlet objects that correspond to the phenomena of charge-spin separation and pairing. Therefore, a close connection between these phenomena and the opening of the spin-gap is revealed.
ENSLAVING RANDOM FLUCTUATIONS IN NONEQUILIBRIUM SYSTEMS
Authors: MAHATO MANGAL C. , PAREEK T.P. , JAYANNAVAR A.M.
Published: October 2004

Several physical models have recently been proposed to obtain unidirectional motion of an overdamped Brownian particle in a periodic system. The asymmetric ratchetlike form of the periodic potential and the presence of correlated nonequilibrium fluctuating forces are considered essential to obtain such a macroscopic motion in homogeneous systems. In the present work, instead, inhomogeneous systems are considered, wherein the friction coefficient and/or temperature could vary in space. We show that unidirectional motion can be obtained even in a symmetric nonratchetlike periodic potential system in the presence of white noise fluctuations. We consider four different cases of system inhomogeneity. We argue that all these different models work under the same basic principle of alteration of relative stability of otherwise locally stable states in the presence of temperature inhomogeneity.
FINITE ELEMENT APPROXIMATIONS FOR THE LAPLACE OPERATOR WITH A RIGHT-HAND SIDE MEASURE
Authors: CLAIN STÉPHANE
Published: October 2004

We study in this paper existence of a solution for problem Δu=µ in fractional Sobolev spaces [Formula: see text] where Ω is an open bounded polygonal convex domain of ℝ2 and µ a measure on Ω. Thanks to this regularity, we obtain estimates for ∇u−∇uh and u–uh in Lp norm where uh is the elliptic projection on a finite element discretized space associated to the Laplace operator.
INTERFACE ESTIMATES FOR THE FULLY ANISOTROPIC ALLEN-CAHN EQUATION AND ANISOTROPIC MEAN-CURVATURE FLOW
Authors: ELLIOTT CHARLES M. , PAOLINI MAURIZIO , SCHÄTZLE REINER
Published: October 2004

In this paper, we prove that solutions of the anisotropic Allen-Cahn equation in double-obstacle form with kinetic term [Formula: see text] in {|φ|<1}, where A is a convex function, homogeneous of degree two, and β depends only on the direction of ∇φ, converge to an anisotropic mean-curvature flow [Formula: see text] Here VN and R denote respectively the normal velocity and the second fundamental form of the interface, and [Formula: see text]. We prove this in the case when the above flow admits a smooth solution, and we establish that the Hausdorff-distance between the zero-level set of φ and the interface of the flow is of order O(ε2).
MULTIDOMAIN PSEUDOSPECTRAL TIME-DOMAIN (PSTD) METHOD FOR ACOUSTIC WAVES IN LOSSY MEDIA
Authors: ZENG YAN QING , LIU QING HUO , ZHAO GANG
Published: October 2004

A multidomain pseudospectral time-domain (PSTD) method is developed for acoustic wave equations in lossy media. The method is based on the spectral derivative operator approximated by Chebyshev Lagrange polynomials. In this multidomain scheme, the computational domain is decomposed into a set of subdomains conformal to the problem geometry. Each curved subdomain is then mapped onto a cube in the curvilinear coordinates so that a tensor-product Chebyshev grid can be utilized without the staircasing error. An unsplit-field, well-posed PML is developed as the absorbing boundary condition. The algorithm is validated by analytical solutions. The numerical solutions show that this algorithm is efficient for simulating acoustic wave phenomena in the presence of complex objects in inhomogeneous media. To our knowledge, the multidomain PSTD method for acoustics is a new development in three dimensions, although in two dimensions the method can be made equivalent to the two-dimensional method in electromagnetics.
SIMULATION OF MUFFLER'S TRANSMISSION LOSSES BY A HOMOGENIZED FINITE ELEMENT METHOD
Authors: BONNET-BENDHIA A. S. , DRISSI D. , GMATI N.
Published: October 2004

In this work, we are interested in the modelling of the acoustic attenuation of exhaust mufflers including perforated ducts, and its numerical computation. The study is worked out in harmonic time regime, for the two-dimensional case. The hole diameter and the center-to-center distance between consecutive holes are supposed of same order, and small compared to the size of the muffler. The formulation is derived by using multiscale techniques and matching the asymptotic expansions. The numerical method couples finite elements in the muffler with modal decomposition in the inlet and the outlet of the duct.
INVESTIGATION OF NEAR-AXIAL INTERFERENCE EFFECTS FOR PROPAGATION IN A DUCTED WAVEGUIDE
Authors: GRIGORIEVA NATALIE S. , FRIDMAN GREGORY M. , PALMER DAVID R.
Published: October 2004

The observed time-of-arrival patterns from a number of long-range ocean acoustic propagation experiments show early geometrical-like arrivals followed by a crescendo of energy that propagates along the sound channel axis and is not resolved into individual arrivals. To describe in a simple model case the interference of near-axial waves which results in forming the so-called axial wave and propose formulas for the axial wave in more general cases, the two-dimensional reference point source problem for the parabolic index of refraction squared is investigated. Using the method proposed by V. Buldyrev, the integral representation for the exact solution is transformed in such a way to extract ray summands corresponding to rays radiated from the source at angles less than a certain angle, the axial wave, and a term corresponding to the sum of all the rays having launch angles greater than the indicated angle. Numerical results for the axial wave and the last term are obtained for parameters corresponding to long-range ocean acoustic propagation experiments.
PROPAGATION OF ACOUSTICS WAVES OF NONSIMPLEX FORM IN A MATERIAL WITH HYSTERETIC QUADRATIC NONLINEARITY: ANALYSIS AND NUMERICAL SIMULATIONS
Authors: ALESHIN V. , GUSEV V. , YU. ZAITSEV V.
Published: October 2004

The numerical scheme for the analysis of the acoustic wave transformation in materials with nonlinearity hysteresis and end-point memory is developed. Both numerical and analytical predictions are obtained concerning mixing of a wave at fundamental frequency (ω-wave) and a wave at doubled frequency (2ω-wave) in the materials with hysteretic quadratic nonlinearity. The observed wave spectrum broadening is found to be in qualitative agreement with the selection rules for the multi-phonon processes in this type of materials. The predicted transformation of an initially complex wave (with four extrema over a period) into a simplex wave (with two extrema over a period) in nonlinear propagation is found to be one of the manifestations of the nonlinear hysteretic absorption. It is demonstrated that at short propagation distances the interaction of the ω- and 2ω-waves is mainly through the mechanism of the nonlinear hysteretic absorption and is not strongly influenced by the process of higher harmonics generation and their inverse influence on the input waves. The regimes of the induced and self-induced transparency are predicted. The influence of the transition from the simplex wave to complex wave emission (or vice versa) on the processes of the induced absorption and transparency is identified.
TIME-DOMAIN FINITE-ELEMENT WAVE FORM INVERSION OF ACOUSTIC WAVE EQUATION
Authors: DI QINGYUN , ZHANG MEIGEN , WANG MIAOYUE
Published: October 2004

The paper derives the finite element equation for acoustic wave in time domain and presents a transparent-plus-attenuation boundary condition. Forward modeling demonstrates that the boundary condition absorbs boundary reflection wave very well. On these bases, we derive the equation satisfied by elements of Jacobi matrix used in the inversion of the physical property parameters of acoustic media. In fact, the equation is the same as that of forward modeling in form. Only the right force item is different. So with the same method of forward modeling, we can get the elements of Jacobi matrix. Because the elements are variable with time and the present inversion does not permit too many unknowns. We integrate the finite elements with the same physical property as one unknown structure unit (for example, a horizontal layer or an oblique layer, etc.) and inverse the physical property parameters of these unknown structure units instead all element's unknown parameters. The method greatly reduces calculation time and saves computer memory. Also, it improves the accuracy of the inversion results and improves the stability of the solving process. The inversion equations are solved with QR decomposition method. Model results prove that the full wave equation inversion method in time domain is effective.
FINITE ELEMENT MODELING OF ACOUSTICS USING HIGHER ORDER ELEMENTS PART II: TURBOFAN ACOUSTIC RADIATION
Authors: LISTERUD EIVIND , EVERSMAN WALTER
Published: October 2004

A study is made of computational accuracy and efficiency for finite element modeling of acoustic radiation in a nonuniform moving medium. For a given level of accuracy for acoustic pressure, cubic serendipity elements are shown to require a less dense mesh than quadratic elements. These elements have been applied to the near field of inlet and aft acoustic radiation models for a turbofan engine and they yield considerable reduction in the dimensionality of the problem without sacrificing accuracy. The results show that for computation of acoustic pressure the cubic element formulation model is superior to the quadratic. Performance gains in computation of acoustic potential are not as significant. In the external radiated field, improved convergence using cubic serendipity elements is shown by comparison of contours of constant pressure magnitude.
RYUKI: A MODEL FOR ZONE-BASED NETWORK WEATHER INFORMATION ON THE INTERNET
Authors: AHMED ASHRAF UDDIN , CHENG ZIXUE , SAITO SENRO
Published: October 2004

Weather information is an excellent representation of atmospheric phenomenon. People with little or no atmospheric knowledge can understand weather forecasts and make good use of it in their daily life. Although Internet information flow does not include this system, it is essential for fitting both the technical and non-technical users. Users need to see the current traffic status of their own ISP or zone, even if some users curiously want to see other zones or the global traffic status. To fulfill this requirement for users, this paper approached a new model called the Ryuki model. In the four planes of the Ryuki model, we captured flow information from the bottom plane, estimated the flows, and introduced three mathematical indices in the second plane. The indices are Ryuki temperature, Ryuki pressure and Ryuki density. The third plane is the service plane where two types of services are introduced. And finally, the top plane represents the network status of the zone. Zone is used as an autonomous system (AS) in this document. A well-known network simulator is used in the simulation for collecting network traffic to estimate the service (QoS and CoS) related information.
LOCKING PROTOCOL FOR INFORMATION FLOW CONTROL
Authors: CHON RYUNG , TAKEDA KOUHEI , ENOKIDO TOMOYA , TAKIZAWA MAKOTO
Published: October 2004

We discuss a novel role locking protocol (RLP) to prevent illegal information flow among objects in a role-based access control (RBAC) model. In this paper, we define a conflicting relation among roles "a role R1 conflicts with another role R2" to show that illegal information flow may occur if a transaction associated with role R1 is performed before another transaction with role R2. Here, we introduce a role lock on an object to abort a transaction with role R1 if another transaction with role R2 had been already performed on the object. Role locks are not released even if transactions issuing the role locks commit. After data in an object o1 flow to another object o2, if the object o1 is updated, the data in the object o2 is independent of the object o1, i.e. obsolete. A role lock on an object can be released if information brought into the object is obsolete. We discuss how to release obsolete role locks. We also discuss how to implement the role locking protocol in single-server and multi-server systems.
AN ENHANCED GNUTELLA P2P PROTOCOL: A SEARCH PERSPECTIVE
Authors: KWOK S. H. , CHAN K. Y.
Published: October 2004

Although Gnutella is the most popular Peer-to-Peer protocol for file sharing, drawbacks are often found in searching and locating files. They include that (1) a limited number of hosts being searched leads to a limited number of hits; (2) the search result is not accurate due to the search by filename; and (3) an inefficient use of computer resource – spending too much resource on handling other peers' queries. In order to rectify these drawbacks, this paper proposes N-phase Search and Passive Search mechanisms. Compared with the traditional search mechanism, N-phase Search increases the number of received query hits by 55.41% and increases the host coverage by 41.23%. For the Passive Search, the average search time is reduced by 15.33%.
AN EFFICIENT CLUSTERED ARCHITECTURE FOR P2P NETWORKS
Authors: LI JUAN , VUONG SON
Published: October 2004

Peer-to-peer (P2P) computing offers many attractive features, such as self-organization, load-balancing, availability, fault tolerance, and anonymity. However, it also faces some serious challenges. In this paper, we propose an Efficient Clustered Super-Peer P2P architecture (ECSP) to overcome the scalability and efficiency problems of existing unstructured P2P system. With ECSP, peers are grouped into clusters according to their topological proximity, and super-peers are selected from regular peers to act as cluster leaders and service providers. These super-peers are also connected to each other, forming a backbone overlay network operating as a distinct, yet integrated, application. To maintain the dynamically adaptive overlay network and to manage the routing on it, we propose an application level broadcasting protocol: Efa. Applying only a small amount of information about the topology of a network, Efa is as simple as flooding, a conventional method used in unstructured P2P systems. By eliminating many duplicated messages, Efa is much more efficient and scalable than flooding, and furthermore, it is completely decentralized and self-organized. Our experimental results prove that ESCP architecture, combined with the super-peer backbone protocol, can generate impressive levels of performance and scalability.
EVALUATION OF KANSEI RETRIEVAL METHOD FOR QUANTITATIVE FEATURE EXTRACTION
Authors: Miyakawa Akihiro , Sugita Kaoru , Ishida Tomoyuki , Shibata Yoshitaka
Published: October 2004

In this paper, we propose a Kansei retrieval method based on the design pattern of traditional Japanese crafting object to provide a user with the desired presentation space in digital traditional Japanese crafting system. The visual quantitative feature values are extracted by using Visual Pattern Image Coding (VPIC). These values include the total number, the frequency, the dispersion rate and the deviation rate for different edges. The quantitative feature values for traditional Japanese crafting objects are registered in the multimedia database and the relation between Kansei words and the visual feature of traditional Japanese crafting objects are analyzed by using the questionnaire. Then, the visual features are compared with the quantitative feature values. Through the above process, we can find the relation between the design pattern components and edge types using VPIC. By finding this relation, the Kansei retrieval method can be realized.
Initial trust and the adoption of B2C e-commerce
Authors: Kim Kyung Kyu , Prabhakar Bipin
Published: October 2004

A possible reason for the delayed acceptance of the Internet as a retail distribution channel may be the lack of trust consumers have in the electronic channel and in the Web merchants. Few prior studies on the adoption of business-to-consumer e-commerce have considered trust in information technology as an important determinant of adoption behavior. This research explicitly encompasses the electronic channel and the merchant as objects to be trusted in a specific e-commerce application, i.e. Internet banking.Our conceptual model posits that initial trust in the electronic channel as a banking medium and trust in bank are the major determinants of adoption behavior. Based on social network theory and trust theory, determinants of trust in the electronic channel such as propensity-to-trust, word-of-mouth (WOM) referrals, structural assurances, are included in the research model.The analyses of independent variables indicated that propensity-to-trust, structural assurances, and relational content of WOM were significant predictors of initial trust in the electronic channel. Our findings also indicated that a significant relationship exists between initial trust in the electronic channel and the adoption of Internet banking. However, further analysis revealed that trust could be a necessary but not a sufficient condition for the adoption of Internet banking.
An extension to on-line multiplication lower bound results
Authors: Cheriton David R.
Published: October 2004

The improved lower bound result of Fischer et al. <2> is extended to a larger class of machines, namely from uniform BAM's to "simple" BAM's.
A note on the transitive closure of a boolean matrix
Authors: Shyamasundar R. K.
Published: October 2004

A row oriented algorithm is given for obtaining the transitive clousure of a Boolean matrix.
Killing two birds with one stone
Authors: Galil Zvi
Published: October 2004

It is shown that the problem of finding the biconnected components of an undirected graph is, in a certain sense, a special case of the problem of finding the strongly connected components of a directed graph. Therefore, the linear-time algorithm for the former can be derived from the linear-time algorithm for the latter.