bluuebunny/crossref_metadata_2025 huggingface dataset:
COMPARTMENTAL MODELING OF MULTIDIMENSIONAL CRYSTALLIZATION
Authors: MA DAVID L. , BRAATZ RICHARD D. , TAFTI DANESH K.
Published: July 2002

An approach that couples compartmental modeling with high resolution methods is developed to simulate spatial variations in the crystal size and shape distribution in solution crystallization processes. This is the first time that compartmental modeling has been applied to a crystal system with multiple characteristic length scales. The compartment model enables a more accurate modeling of the effect of secondary nucleation, which is key to accurately predicting the crystal size distribution of the final product. A parallel implementation of the numerical algorithm results in short computation times.
STOCHASTIC DESCRIPTION OF AGGLOMERATION AND GROWTH PROCESSES IN GLASSES
Authors: KERNER RICHARD
Published: July 2002

We show how growth by agglomeration can be described by means of algebraic or differential equations which determine the evolution of probabilities of various local configurations. The minimal fluctuation condition is used to define vitrification. Our methods have been successfully used for the description of glass formation.
WHAT IS A ROTON?
Authors: REATTO L. , GALLI D. E.
Published: July 2002

Many models of a roton in superfluid 4 He have been proposed over the years but no general consensus has been reached yet on the nature of such excitation. We present a number of new results relating to this question. We have developed an accurate representation of the wave function of such excitation which is based on a shadow function. This allows to treat the short range backflow effects in a non perturbative way. The theory gives results in quantitative agreement with experiment. Starting from such eigenstates of momentum we build wave–packets and study local quantities like density, momentum and vorticity. No model agrees with our results for the excitations in the roton minimum region because we find that the excitations have in a varying degree characters of single particle, of non quantized smoke ring and of collective excitation. We have also considered 4 He in two dimensions and we find similar results. In 2D we have studied also maxon and high frequency phonon wave–packets.
The Effects of the Breakdown of Migdal's Theorem in Various Superconductors
Authors: Ummarino G. A. , Gonnelli R. S.
Published: July 2002

In this work we investigate some effects of the breakdown of Migdal's theorem in high and low-Tc superconductors. In the cuprates the electronic bandwidth has a very low value compared to the characteristic phonon energy and, in order to reproduce the experimental Tc and tunneling data in the framework of the Eliashberg theory for strong electron-boson interaction it is necessary to use large values of the coupling constant. Our purpose is to numerically quantify the correlation between the amount of violation of the Migdal's theorem and the renormalization of the coupling constant λ, of the gap Δ and of Tc by examining different kinds of superconducting materials. For this task we use the theoretical approach developed by Grimaldi, Pietronero and Strässler [PRB 52, 10516 & 10530, 1995], together with the real-axis direct solution of the Eliahsberg equations in s -wave pair symmetry.
New Actuators Using ER Fluid and Their Applications to Force Display Devices in Virtual Reality and Medical Treatments
Authors: Furusho Junji , Sakaguchi Masamichi
Published: July 2002

We developed ER actuators with low inertia. ER actuator is a torque-controllable clutch which uses an electrorheological fluid. It is shown that this actuator has good properties for force display device, physical therapy treatment, etc. We developed new force display devices for virtual reality which use ER actuators.
CRITICAL PROPERTIES OF A MAGNETIZED BOSE GAS
Authors: RABUFFO I.
Published: July 2002

The critical behaviour of a dilute spin-S Bose gas in a magnetic field is investigated with the help of the renormalization group method. A complete set of critical exponents is given both at constant pressure and constant density. The magnetic properties are also discussed.
GAS-BUBBLE ORDERING IN NANOPOROUS SURFACE FORMATION IN HELIUM-IMPLANTED METALS
Authors: JOHNSON P. B. , GILBERD P. W. , MORRISON YVONNE , VAROY C. R.
Published: July 2002

The nanoporous surfaces that can be produced by ion implantation of helium into metals have considerable potential for applications. The structures are characterised by random nanoscale cavities of uniform size, a high degree of swelling and very thin metal "walls" separating the neighbouring cavities. These structures are "seeded" by an earlier stage - a gas-bubble superlattice - comprising small helium bubbles again of uniform size (~ 2 nm diameter) ordered on a space lattice having the same symmetry as the host. For the fcc metals the bubble superlattice always contains structural variants - that is, regions where the ordered bubble array has an orientation that is rational with, but different from, that of the crystal lattice of the host metal. In contrast for bcc metals previous work has suggested that the bubble lattice aligns solely parallel with the host crystal. Here we report the first clear demonstration of the presence of structural variant bubble lattices in a bcc metal. A combination of techniques including helium depth-profiling using HERDA is enabling the helium dose requirements for producing ordered bubble structures to be investigated more closely. These techniques are reviewed.
EXTRACTING SEMANTIC INFORMATION THROUGH AUTOMATIC LEARNING TECHNIQUES
Authors: SEGARRA E. , SANCHIS E. , GALIANO M. , GARCIA F. , HURTADO L.
Published: July 2002

We present an approach for the development of Language Understanding systems from a Transduction point of view. We describe the use of two types of automatically inferred transducers as the appropriate models for the understanding phase in dialog systems.
SIMPLEST ODE EQUIVALENTS OF CHUA'S EQUATIONS
Authors: POSPÍŠIL JIŘÍ , KOLKA ZDENĚK , HORSKÁ JANA , BRZOBOHATÝ JAROMÍR
Published: July 2002

The so-called elementary canonical state models of the third-order piecewise-linear (PWL) dynamical systems, as the simplest ODE equivalents of Chua's equations, are presented. Their mutual relations using the linear topological conjugacy are demonstrated in order to show in detail that Chua's equations and their canonical ODE equivalents represent various forms of qualitatively equivalent models of third-order dynamical systems. New geometrical aspects of the corresponding transformations together with examples of typical chaotic attractors in the stereoscopic view, give the possibility of a deeper insight into the third-order system dynamics.
COMPLETE STABILITY FOR A CLASS OF CELLULAR NEURAL NETWORKS
Authors: SHIH CHIH-WEN
Published: July 2002

This work investigates a class of lattice dynamical systems originated from cellular neural networks. In the vector field of this class, each component of the state vector and the output vector is related through a sigmoidal nonlinear output function. For two types of sigmoidal output functions, Liapunov functions have been constructed in the literatures. Complete stability has been studied for these systems using LaSalle's invariant principle on the Liapunov functions. The purpose of this presentation is two folds. The first one is to construct Liapunov functions for more general sigmoidal output functions. The second is to extend the interaction parameters into a more general class, using an approach by Fiedler and Gedeon. This presentation also emphasizes the complete stability when the equilibrium is not isolated for the standard cellular neural networks.
UNCERTAINTY IN CHAOS SYNCHRONIZATION
Authors: ZHONG GUO-QUN , MAN KIM-FUNG , KO KING-TIM
Published: July 2002

In this paper a variety of uncertainty phenomena in chaos synchronization, which are caused by the sensitive dependence on initial conditions and coupling strength, are numerically investigated. Two identical Chua's circuits are considered for both mutually- and unidirectionally-coupled systems. It is found that initial states of the system play an important role in chaos synchronization. Depending on initial conditions, distinct behaviors, such as in-phase synchronization, anti-phase synchronization, oscillation-quenching, and bubbling of attractors, may occur. Based on the findings, we clarify that the systems, which satisfy the standard synchronization criterion, do not necessarily operate in a synchronization regime.
TAMING CHAOS IN A DRIVEN JOSEPHSON JUNCTION
Authors: CHACÓN R. , PALMERO F. , BALIBREA F.
Published: July 2002

We present analytical and numerical results concerning the inhibition of chaos in a single driven Josephson junction by means of an additional weak resonant perturbation. From Melnikov analysis, we theoretically find parameter-space regions, associated with the chaos-suppressing perturbation, where chaotic states can be suppressed. In particular, we test analytical expressions for the intervals of initial phase difference between the two excitations for which chaotic dynamics can be eliminated. All the theoretical predictions are in overall good agreement with numerical results obtained by simulation.
SPECTRAL MOMENTS AND THE ANALYSIS OF CHAOTIC SYSTEMS
Authors: KOUSSOULAS NICK T.
Published: July 2002

The simplicity of structure of chaotic systems, combined with the richness of their output, inspires their use in modeling efforts. On the other hand, the difficulty of their analysis warrants approximation methods, especially since the absence, by definition, of well-defined limit sets prohibits, in general, a meaningful linearization. In this work we present some results, which can support a methodology founded on spectral analysis for approximating chaotic systems via stochastic linear systems. The main contribution is the use of spectral moments for identifying the location of embedded limit cycles and the spectrum-based validation of approximations.
MECHANICAL MODELS OF CHUA'S CIRCUIT
Authors: AWREJCEWICZ J. , CALVISI M. L.
Published: July 2002

In this paper we present two different examples of electromechanical realization of Chua's circuit and one of Chua's unfolding circuit. In addition, a novel mechanism is proposed for realizing Chua's equations in a purely mechanical way using friction properties. All relevant equations are derived and the mechanical realizations of the proposed devices are discussed.
OPTIMUM CORRELATOR-TYPE RECEIVER DESIGN FOR CSK COMMUNICATION SYSTEMS
Authors: LAU FRANCIS C. M. , TSE CHI K.
Published: July 2002

In a chaos-shift-keying (CSK) digital communication system, correlators followed by a comparator are typically used for coherent detection of the signal. Such a detection method, however, does not take the temporal variation of the bit energy into consideration. In this paper, an optimum detection for a binary CSK system is derived, taking into account the temporal variation of the bit energy for minimizing the error rates. Simulations are carried out to compare the performance between the optimum receiver and a typical receiver. The results provide theoretical performance benchmarks of coherent CSK systems for future references.
ALEXANDER GROUPS AND VIRTUAL LINKS
Authors: SILVER DANIEL S. , WILLIAMS SUSAN G.
Published: July 2002

The extended Alexander group of an oriented virtual link l of d components is defined. From its abelianization a sequence of polynomial invariants Δi (u1,…,ud, v), i=0, 1,…, is obtained. When l is a classical link, Δi reduces to the well-known ith Alexander polynomial of the link in the d variables u1v,…,udv; in particular, Δ0 vanishes.
ON TWO DIMENSIONAL KNOTS WITH RECIPROCAL POLYNOMIALS
Authors: NAKANISHI YASUTAKA , NISHIZAWA KAZUO
Published: July 2002

In this note, we will study 2-knots, which have a projection with parallel-loop singularities. We will show that such a 2-knot has a reciprocal Alexander polynomial.
COSMIC STRINGS, LOOPS, AND LINEAR GROWTH OF MATTER PERTURBATIONS
Authors: WU JIUN-HUEI PROTY , AVELINO PEDRO P. , SHELLARD E. P. S. , ALLEN BRUCE
Published: July 2002

We describe a detailed study of string-seeded structure formation using high resolution numerical simulations in open universes and those with a non-zero cosmological constant. We provide a semi-analytical model which can reproduce these simulation results including the effect from small loops chopped of by the string network. A detailed study of cosmic string network properties regarding structure formation is also given, including the correlation time, the topological analysis of the source spectrum, the correlation between long strings and loops, and the evolution of long-string and loop energy densities. For models with Γ=Ω h=0.1 -0.2 and a cold dark matter background, we show that the linear density fluctuation power spectrum induced by cosmic strings has both an amplitude at 8 h-1 Mpc, σ8, and an overall shape which are consistent within uncertainties with those currently inferred from galaxy surveys. The cosmic string scenario with hot dark matter requires a strongly scale-dependent bias in order to agree with observations.
RADIAL MODES OF ROTATING NEUTRON STARS IN THE CHANDRASEKHAR–FRIEDMAN FORMALISM
Authors: DATTA B. , HASAN S. S. , SAHU P. K. , PRASANNA A. R.
Published: July 2002

Eigenfrequencies of radial pulsations of "slowly" rotating neutron stars are calculated in a general relativistic formalism given by Chandrasekhar & Friedman. It is found that the square of the frequencies are always a decreasing function of the central density of the neutron star. The decrease of the squared frequency is sensitive to the equation of state of neutron star matter, and is illustrated using realistic models.
PRIMORDIAL MAGNETIC FIELD AND SPECTRAL DISTORTION OF COSMIC BACKGROUND RADIATION
Authors: PUY DENIS , PETER PATRICK
Published: July 2002

The role played by a primordial magnetic field during the pre-recombination epoch is analysed through the cyclotron radiation (due to the free electrons) it might produce in the primordial plasma. We discuss the constraint implied by the measurement or lack thereof COBE on this primordial field.
A MATHEMATICAL MODEL TO STUDY THE EFFECT OF TOXIC CHEMICALS ON A PREY-PREDATOR TYPE FISHERY
Authors: GHOSH MINI , CHANDRA PEEYUSH , SINHA PRAWAL
Published: July 2002

In this paper, a nonlinear mathematical model is proposed and analyzed to see the indirect effect of air pollutants on the prey-predator type fish population in a closed population (lake). It is shown that as the pollutant concentration in the environment increases, the concentration of the acidic chemicals in the lake increases and consequently the equilibrium level of the fish population decreases. Using stability theory of differential equations and computer simulation, it is shown that due to the effort, pollutant concentration can be reduced to a desired level to save fisheries from extinction by acid rain.
TRIANGLE-QUADRANGLE GRID METHOD FOR POROELASTIC, ELASTIC, AND ACOUSTIC WAVE EQUATIONS
Authors: ZHANG JIANFENG
Published: July 2002

A new numerical technique is developed for wave propagation in heterogeneous poroelastic media and mixed poroelastic, elastic and acoustic media. The scheme, based on a first-order hyperbolic Biot's system and a discretization mesh of triangles and quadrangles, solves the problem using integral equilibrium equations around each node, instead of satisfying Biot's differential equations at each node as in the finite-difference method. The surface topography and complex geometrical interfaces can be accurately modeled with the proposed algorithm by making the nodes of triangles and quadrangles follow the curved interfaces. The elastic (acoustic)/poroelastic interface conditions of complex geometry are introduced using the integral equilibrium equations around nodes at the interface based on the continuities of total stresses and velocities between the interface. The free-surface conditions of complex geometrical boundaries are satisfied naturally for the scheme. This work is an extension of the grid method for the heterogeneous elastic media to the heterogeneous poroelastic one. The proposed algorithm is successfully tested against an analytical solution for Lamb's problem when the algorithm is reduced to handle the elastic limit of the Biot's equations. Examples of wave propagation in a poroelastic half-space with a semi-cylindrical pit on the surface and mixed acoustic-poroelastic and elastic-poroelastic models with inclined interfaces are presented.
A NEW VARIABLES CONTROL CHART FOR SIMULTANEOUSLY MONITORING MULTIVARIATE PROCESS MEAN AND VARIABILITY
Authors: YEH ARTHUR B. , LIN DENNIS K. J.
Published: July 2002

In this paper, we propose a new variables control chart, called the box-chart, to simultaneously monitor, on a single chart, the process mean and process variability for multivariate processes. The box-chart uses a probability integral transformation to obtain two independently and identically distributed uniform distributions. Therefore, a box-shaped (thus the name), two-dimensional control chart can be constructed. We discuss in detail on how to construct the box-chart. The proposed chart is applied to two real-life examples. The performance of the box-chart is also compared to that of the traditional T2- and |S|-charts.
A COMPARISON OF LEED CALCULATIONAL METHODS FOR STEPPED SURFACES
Authors: JEPSEN D. W.
Published: July 2002

Several methods for calculating LEED spectra from stepped surfaces, including layer doubling and transfer matrix (CHANGE), are compared for calculations of LEED spectra from vicinal (stepped) surfaces with their narrow spacings between planes. A particular type of failure which occurs only for certain spacings from top bulk layer to bottom surface layer is analyzed.
ANTERIOR INTEROSSEOUS NERVE SYNDROME
Authors: Arishita Gary L. , Tsai Tsu-Min
Published: July 2002

The anterior interosseous nerve syndrome was first described in 1948. It comprises less than 1% of all upper extremity nerve palsies. Patients have a characteristic pinch deformity, with paralysis or weakness of the muscles innervated by the anterior interosseous nerve, flexor pollicis longus, radial portion of the flexor digitorum profundus, and pronator quadratus. Electromyograms are positive in most patients presenting with motor complaints. Treatment is related to the specific etiology. Conservative treatment includes avoidance of strenuous forearm work, immobilization, steroid injections, and anti-inflammatory medications. If the presentation suggests nerve compression, and the EMG reveals evidence of axonal interruption, then surgical decompression should be performed. We present a series of six patients seen over a 7-year period. Improvement was noted in all the patients postoperatively.
THE ETIOLOGY OF KIENBÖCK'S DISEASE — A HISTOPATHOLOGICAL STUDY
Authors: Simank H.-G. , Schiltenwolf M. , Krempien W.
Published: July 2002

The etiology of the necrosis of the lunate bone is still unclear. In today's theories, the necrosis is explained by impairment of the arterial bone circulation or fracture following mechanical overloading. In this study, six specimen in different stages of the disease were investigated histologically. In all the specimens, focal necrosis was detected, but also signs of regeneration, i.e. immature bone formation. No signs of fracture were seen in all stages of the disease. These findings are not compatible with sudden interruption of arterial blood supply or fracture of the lunate bone as a primary lesion. Comparable histological patterns are known in the necrosis of the femoral head. The etiological model of necrosis of the femoral head is well investigated and postulates primary marrow hypertension, induced by impairment of the venous drainage. Our results are contradictory to the etiological theories of fracture or breakdown of the arterial blood supply as a primary lesion in Kienböck's disease, and support the assumption that the model of intraosseous hypertension is transferable to the necrosis of the lunate bone.
EXPRESSION OF CYTOKINES IN THE DORSAL ROOT GANGLION CELL BODY IN AN EXPERIMENTAL MODEL OF ENTRAPMENT NEUROPATHY
Authors: Yamamoto S. , Ochi M. , Shu N. , Ryoke K. , Yamaguchi H.
Published: July 2002

An experimental entrapment neuropathy model was produced by wrapping the sciatic nerve with a silicone tube using 54 adult male Wistar rats. We observed the changes in expression of IL-1 and TGF-β1 in the dorsal root ganglion during the formation as well as recovery process after removal of the tube, together with electrophysiological changes. Expression of IL-1 reached its peak 2 months after tubing, while expression of TGF-β1 peaked at 6 months and thereafter slowly decreased. Motor nerve conduction velocity (MNCV) significantly decreased 8 months after tubing. Removal of the silicone tube at 8 months after tubing, induced a significant increase in the level of IL-1 expression at 1 month after the removal, and that in the level of TGF-β1 expression at 2 months after the removal, at which time MNCV began to show a significant recovery. We have concluded from these results that IL-1 and TGF-β1 are deeply involved in the formation as well as the recovery process of entrapment neuropathy.
MULTIPLE ENTRAPMENT NEUROPATHY IN THE UPPER EXTREMITY
Authors: Chen I-Chen , Zhang Gao-Meng , Tsai Tsu-Min
Published: July 2002

Multiple entrapment neuropathy is compression of more than two nerves in the same extremity. In this case series, 169 patients (208 upper extremities) with this condition were identified, and 124 patients (138 upper extremities) had surgical decompression after an ineffective course of conservative treatment. There were 31 men and 93 women. Average age was 41 years (range 20–87 years). Follow-up averaged 23 months (range 12 to 60 months). Our rating system included patients' self-assessment of overall symptom improvement and return to activity and a physician assessment of strength (grip and pinch) and sensibility (recovery of two-point discrimination). A total of 92 patients (67%) achieved good to excellent results. The clinical features of multiple entrapment neuropathy in our series were presented with a variety of nerve compression syndromes and with a high incidence of regional musculotendinous syndromes. In our surgical treatment, we emphasise simultaneous release of all possible compression sites with a minimally invasive endoscopic approach to achieve better results.
IMPRECISE ANSWERS IN DISTRIBUTED ENVIRONMENTS: ESTIMATION OF INFORMATION LOSS FOR MULTI-ONTOLOGY BASED QUERY PROCESSING
Authors: MENA E. , KASHYAP V. , ILLARRAMENDI A. , SHETH A.
Published: July 2002

The World Wide Web is fast becoming a ubiquitous computing environment. Prevalent keyword-based search techniques are scalable, but are incapable of accessing information based on concepts. We investigate the use of concepts from multiple, real-world pre-existing, domain ontologies to describe the underlying data content and support information access at a higher level of abstraction. It is not practical to have a single domain ontology to describe the vast amounts of data on the Web. In fact, we expect multiple ontologies to be used as different world views and present an approach to "browse" ontologies as a paradigm for information access. A critical challenge in this approach is the vocabulary heterogeneity problem. Queries are rewritten using interontology relationships to obtain translations across ontologies. However, some translations may not be semantics preserving, leading to uncertainty or loss in the information retrieved. We present a novel approach for estimating loss of information based on the navigation of ontological terms. We define measures for loss of information based on intensional information as well as on well established metrics like precision and recall based on extensional information. These measures are used to select results having the desired quality of information.
INCOMPLETE INFORMATION WITH RECURSIVE PREFERENCES
Authors: CVITANIĆ JAKSA , LAZRAK ALI , QUENEZ MARIE CLAIRE , ZAPATERO FERNANDO
Published: July 2002

We consider the case of an agent with recursive preferences (Stochastic Differential Utility or SDU) who cannot observe the random drift of the stock price process. This partial information problem can be transformed into a problem with full information, in which the drift is replaced by its expected value conditional on the information given by the stock price history. We are then in a position to use recent results for maximizing SDUs under full information and their connection to Forward-Backward Stochastic Differential Equations. They enable us to study qualitative differences between the cases with full and partial information. We also analyze some special cases in which we obtain semi-explicit results and compute the SDU numerically.
ON THE SEMIVALUES AND THE POWER CORE OF COOPERATIVE TU GAMES
Authors: DRAGAN IRINEL , MARTINEZ-LEGAZ JUAN ENRIQUE
Published: July 2002

A weighted average worth per capita formula is presented for any semivalue of a TU game. Further, this formula is used to derive a characterisation of the class of games with the property that a given semivalue belongs to the power core of the game, by means of a linear system of inequalities. It is shown that for the Shapley value, the only efficient semivalue, this system reduces to the system already obtained by Inarra and Usategui. The potential approach is also used even for the more general case of values possessing a potential. A direct proof shows that for a value possessing a potential, the value of a game is in the power core relative to this value, if and only if the potential game is weak average convex. From this result, it follows that for a game and each of its subgames the value possessing a potential is in the corresponding power cores, if and only if the potential game relative to the value is average convex. This is an extension of the result obtained by Marin–Solano and Rafels for the Shapley value, proved by using the dividend form of the game.
STABILIZING HIERARCHICAL ROUTING
Authors: DATTA AJOY K. , DERBY JERRY L. , LAWRENCE JAMES E. , TIXEUIL SÉBASTIEN
Published: July 2002

Hierarchical routing provides a less expensive algorithm compared to the traditional all-pairs routing algorithms. We present an algorithm in this paper which benefits from the lower memory requirement, faster routing table lookup, and less costly broadcast exemplified by hierarchical routing, and yet maintains routing capability of all pairs of connected nodes even in the presence of faults, such as link/node failures and repairs, and corruption of program variables. Additionally, this algorithm solves the problem of cluster partitioning where nodes that are supposed to be in the same subset of the network, become isolated due to link or node failures. Being self-stabilizing, starting from an arbitrary state (with possibly corrupted routing tables), the protocol is guaranteed to reach a configuration with routing tables containing valid entries in a finite time. The protocol automatically updates the shortest paths in the face of dynamically changing link weights. The proposed protocol also dynamically allocates/deallocates storage for the routing information as the network size changes. The algorithm works on an arbitrary topology and under a distributed daemon model.
FROM JOIN-IRREDUCIBLES TO DIMENSION THEORY FOR LATTICES WITH CHAIN CONDITIONS
Authors: WEHRUNG FRIEDRICH
Published: July 2002

For a finite lattice L, the congruence lattice Con L of L can be easily computed from the partially ordered set J (L) of join-irreducible elements of L and the join-dependency relation DLon J (L). We establish a similar version of this result for the dimension monoid Dim L of L, a natural precursor of Con L. For L join-semidistributive, this result takes the following form:

Theorem 1. Let L be a finite join-semidistributive lattice. Then Dim L is isomorphic to the commutative monoid defined by generators Δ(p), for p ∈ J(L), and relations [Formula: see text]

As a consequence of this, we obtain the following results:

Theorem 2. Let L be a finite join-semidistributive lattice. Then L is a lower bounded homomorphic image of a free lattice iff Dim L is strongly separative, iff it satisfies the axiom [Formula: see text]

Theorem 3. Let A and B be finite join-semidistributive lattices. Then the box product A □ B of A and B is join-semidistributive, and the following isomorphism holds: [Formula: see text] where ⊗ denotes the tensor product of commutative monoids.
RADIAL AND AXIAL SEGREGATION OF GRANULAR MIXTURES IN THE ROTATING-DRUM GEOMETRY
Authors: PURI SANJAY , HAYAKAWA HISAO
Published: July 2002

We formulate a phenomenological model for the dynamical evolution of granular mixtures in a rotating drum. In particular, we present a dynamical basis for an "effective surface tension," which penalizes sharp interfaces between regions enriched in different components of the mixture. We also present representative results which demonstrate that our model captures many experimental features for this problem.
VIRTUAL REALITY FOR SUPPORTING THE CONFIGURATION OF TRANSFORMABLE ASSEMBLY SYSTEMS
Authors: MERSINGER MARKUS , WESTKÄMPER ENGELBERT
Published: July 2002

Virtual Reality (VR) made its way out of research labs into industrial applications like product design, design for assembly, training issues, etc. Nevertheless, VR is still suffering from lacking technology to highlight its huge amount of functionality. That means the utilization of VR in a holistic way to combine the real and the virtual world to close the circle, in which the user can switch between both systems is still not common. There is more VR can contribute than an immersive 3D model of real objects and some interaction technology with different devices like 6 DOF mouse, PhantomTM, gloves with tactile feedback, etc. If you want to use VR like the usual technology, you have to integrate the features of 3D, interaction, force feedback, simulation and the real system.

The research work to develop such an integrated system is done within a special research project (SFB 467) of the German Research Society (DFG) called "Transformable business structures for multiple-variant series production".
Algorithm 693: a FORTRAN package for floating-point multiple-precision arithmetic
Authors: Smith David M.
Published: July 2002

FM is a collection of FORTRAN-77 routines which performs floating-point multiple-precision arithmetic and elementary functions. Results are almost always correctly rounded, and due to improved algorithms used for elementary functions, reasonable efficiency is obtained.
Formal semantics of SQL queries
Authors: Negri M. , Pelagatti G. , Sbattella L.
Published: July 2002

The semantics of SQL queries is formally defined by stating a set of rules that determine a syntax-driven translation of an SQL query to a formal model. The target model, called Extended Three Valued Predicate Calculus (E3VPC), is largely based on a set of well-known mathematical concepts. The rules which allow the transformation of a general E3VPC expression to a Canonical Form, which can be manipulated using traditional, two-valued predicate calculus are also given; in this way, problems like equivalence analysis of SQL queries are completely solved. Finally, the fact that reasoning about the equivalence of SQL queries using two-valued predicate calculus, without taking care of the real SQL semantics can lead to errors is shown, and the reasons for this are analyzed.
The computation of eigenvalues and solutions of Mathieu's differential equation for noninteger order
Authors: Shirts Randall B.
Published: July 2002

Two algorithms for calculating the eigenvalues and solutions of Mathieu's differential equation for noninteger order are described. In the first algorithm, Leeb's method is generalized, expanding the Mathieu equation in Fourier series and diagonalizing the symmetric tridiagonal matrix that results. Numerical testing was used to parameterize the minimum matrix dimension that must be used to achieve accuracy in the eigenvalue of one part in 10
12
. This method returns a set of eigenvalues below a given order and their associated solutions simultaneously. A second algorithm is presented which uses approximations to the eigenvalues (Taylor series and asymptotic expansions) and then iteratively corrects the approximations using Newton's method until the corrections are less than a given tolerance. A backward recursion of the continued fraction expansion is used. The second algorithm is faster and is optimized to obtain accuracy of one part in 10
14
, but has only been implemented for orders less than 10.5.
Integration of interpersonal space and shared workspace
Authors: Ishii Hiroshi , Kobayashi Minoru , Grudin Jonathan
Published: July 2002

We describe the evolution of the novel shared drawing medium ClearBoard which was designed to seamlessly integrate an interpersonal space and a shared workspace. ClearBoard permits coworkers in two locations to draw with color markers or with electronic pens and software tools while maintaining direct eye contact and the ability to employ natural gestures. The ClearBoard design is based on the key metaphor of “talking through and drawing on a transparent glass window.” We describe the evolution from ClearBoard-1 (which enables shared video drawing) to ClearBoard-2 (which incorporates TeamPaint, a multiuser paint editor). Initial observations and findings gained through the experimental use of the prototype, including the feature of “gaze awareness,” are discussed. Further experiments are conducted with ClearBoard-0 (a simple mockup), ClearBoard-1, and an actual desktop as a control. In the settings we examined, the ClearBoard environment led to more eye contact and potential awareness of collaborator's gaze direction over the traditional desktop environment.
An algebraic theory of class specification
Authors: Parisi-Presicce Francesco , Pierantonio Alfonso
Published: July 2002

The notion of class (or object pattern) as defined in most object-oriented languages is formalized using known techniques from algebraic specifications. Inheritance can be viewed as a relation betweeen classes, which suggests how classes can be arranged in hierarchies. The hierarchies contain two kinds of information: on the one hand, they indicate how programs are structured and how code is shared among classes; on the other hand, they give information about compatible assignment rules, which are based on subtyping. In order to distinguish between code sharing, which is related to implementational aspects, and functional specialization, which is connected to the external behavior of objects, we introduce an algebraic specification-based formalism, by which one can specify the behavior of a class and state when a class inherits another one. It is shown that reusing inheritance can be reduced to specialization inheritance with respect to a virtual class. The class model and the two distinct aspects of inheritance allow the definition ofcleaninterconnection mechanisms between classes leading to new classes which inherit from old classes their correctness and their semantics.
A qualitative simulation approach for fuzzy dynamical models
Authors: Bonarini Andrea , Bontempi Gianluca
Published: July 2002

This article deals with simulation of approximate models of dynamic systems. We propose an approach that is appropriate when the uncertainty intrinsic in some models cannot be reduced by traditional identification techniques, due to the impossibility of gathering experimental data about the system itself. The article presents a methodology for qualitative modeling and simulation of approximately known systems. The proposed solution is based on the Fuzzy Sets theory, extending the power of traditional numerical-logical methods. We have implemented a fuzzy simulator that integrates a fuzzy, qualitative approach and traditional, quantitative methods.
Feedback techniques for continuity and synchronization in multimedia information retrieval
Authors: Rangan P. Venkat , Ramanathan Srinivas , Sampathkumar Srihari
Published: July 2002

Future advances in storage and networking technologies will make it feasible to build multimedia on-demand information servers capable of providing services similar to those of a neighborhood videotape rental store over metropolitan area networks. Such multimedia information servers must not only support retrieval of continuous media units (such as video frames and audio samples), but also preserve synchrony among playback of the different media components constituting a multimedia object. We develop techniques for supporting continuous and synchronous retrieval from multimedia servers. We present feedback techniques by which, during retrieval of multimedia objects from a multimedia server to mediaphones, the multimedia server uses lightweight messages called
feedback units
transmitted periodically back to it (by mediaphones) to detect impending discontinuities as well as asynchronies at mediaphones. The multimedia server then preventively readjusts media transmission so as to avoid either anomaly, and steers the mediaphones back to synchrony. Given the available buffer sizes at mediaphones and the maximum tolerable asynchrony, we present methods to determine the minimum rate at which feedback units must be transmitted so as to maintain both continuity and synchronization. These feedback techniques remain robust even in the presence of playback rate mismatches and network delay jitter, and their initial simulation for video-audio playback yields a feedback rate of one per 1,000 media units to keep the asynchrony within 250ms, showing that the overhead due to feedback transmission is very small. The constant rate feedback techniques developed in this article form the basis of a prototype on-demand information server being developed at the UCSD Multimedia Laboratory.
Comparing data modeling formalisms
Authors: Kim Young-Gul , March Salvatore T.
Published: July 2002

Accurate specification and validation of information requirements is critical to the development of organizational information systems.
Semantic data models
were developed to provide a precise and unambiguous representation of organizational information requirements [9, 17]. They serve as a communication vehicle between analysts and users. After analyzing 11 semantic data models, Biller and Neuhold [3] conclude that there are essentially only two types of data modeling formalisms:
entity-attribute-relationship
(EAR) models and
object-relationship
(OR) models. Proponents of each claim their model yields “better” representations [7] than the other. There is, however, little empirical evidence to substantiate these claims.
Commercial applications of natural language processing
Authors: Church Kenneth W. , Rau Lisa F.
Published: July 2002

Vast quantities of text are becoming available in electronic form, ranging from published documents (e.g., electronic dictionaries, encyclopedias, libraries and archives for information retrieval services), to private databases (e.g., marketing information, legal records, medical histories), to personal email and faxes. Online information services are reaching mainstream computer users. There were over 15 million Internet users in 1993, and projections are for 30 million in 1997. With media attention reaching all-time highs, hardly a day goes by without a new article on the National Information Infrastructure, digital libraries, networked services, digital convergence or intelligent agents. This attention is moving natural language processing along the critical path for all kinds of novel applications.
Further experience with controller-based automatic motion synthesis for articulated figures
Authors: Auslander Joel , Fukunaga Alex , Partovi Hadi , Christensen Jon , Hsu Lloyd , Reiss Peter , Shuman Andrew , Marks Joe , Ngo J. Thomas
Published: July 2002

We extend an earlier automatic motion-synthesis algorithm for physically realistic articulated figures in several ways. First, we summarize several incremental improvements to the original algorithm that improve its efficiency significantly and provide the user with some ability to influence what motions are generated. These techniques can be used by an animator to achieve a desired movement style, or they can be used to guarantee variety in the motions synthesized over several runs of the algorithm. Second, we report on new mechanisms that support the concatenation of existing, automatically generated motion controllers to produce complex, composite movement. Finally, we describe initial work on generalizing the techniques from 2D to 3D articulated figures. Taken together, these results illustrate the promise and challenges afforded by the controller-based approach to automatic motion synthesis for computer animation.
Combining antithetic variates and control variates in simulation experiments
Authors: Yang Wei-Ning , Liou Wei-Win
Published: July 2002

Antithetic variates and control variates are two well-known variance reduction techniques. We consider combining antithetic variates and control variates to estimate the mean response in a stochastic simulation experiment. When applying antithetic variates to generate control variates across paired replications, we show that the integrated control-variate estimator is unbiased and yields, under the assumption of common correlations induced for all control variates, a smaller variance than the conventional control-variate estimator without using antithetic variates. We examine the proposed estimator and two alternative integrated control-variate estimators when applying antithetic variates on control variates and show that the proposed estimator is the optimal integrated control-variate estimator We implement these three integrated control-variate estimators and the conventional control-variate estimator in a simulation model of a stochastic network to evaluate the performance of each control-variate estimator Empirical results show that the proposed estimator outperforms the other control-variate estimators.
Algorithm 768: TENSOLVE
Authors: Bouaricha Ali , Schnabel Robert B.
Published: July 2002

This article describes a modular solftware package for solving systems of nonlinear equations and nonlinear problems, using a new class of methods called tensor methods. It is intended for small- to medium-sized problems, say with up to 100 equations and unknowns, in cases where it is reasonable to calculate the Jacobian matrix or to approximate it by finite differences at each iteration. The software allows the user to choose between a tensor method and a standard method based on a linear model. The tensor method approximates
F
(
x
) by a quadratic model, where the second-order term is chosen so that the model is hardly more expensive to form, store, or solve than the standard linear model. Moreover, the software provides two different global strategies: a line search approach and a two-dimensional trust region approach. Test results indicate that, in general, tensor methods are significantly more efficient and robust than standard methods on small- and medium-sized problems in iterations and function evaluations.
Rational parametrizations of nonsingular real cubic surfaces
Authors: Bajaj Chandrajit L. , Holt Robert L. , Netravali Arun N.
Published: July 2002

Real cubic algebraic surfaces may be described by either implicit or parametric equations. One particularly useful representation is the rational parametrization, where the three spatial coordinates are given by rational functions of two parameters. These parametrizations take on different forms for different classes of cubic surfaces. Classification of real cubic algebraic surfaces into five families for the nonsingular case is based on the configuration of 27 lines on them. We provide a method of extracting all these lines by constructing and solving a polynomial of degree 27. Simple roots of this polynomial correspond to real lines on the surface, and real skew lines are used to form rational parametrizations for three of these families. Complex conjugate skew lines are used to parametrize surfaces from the fourth family. The parametrizations for these four families involve quotients of polynomials of degree no higher than four. Each of these parametrizations covers the whole surface except for a few points, lines, or conic sections. The parametrization for the fifth family, as noted previously in the literature, requires a square root. We also analyze the image of the derived rational parametrization for both real and complex parameter values, together with “base” points where the parametrizations are ill-defined.
Three-dimensional distance field metamorphosis
Authors: Cohen-Or Daniel , Solomovic Amira , Levin David
Published: July 2002

Given two or more objects of general topology, intermediate objects are constructed by a distance field metamorphosis. In the presented method the interpolation of the distance field is guided by a warp function controlled by a set of corresponding anchor points. Some rules for defining a smooth least-distorting warp function are given. To reduce the distortion of the intermediate shapes, the warp function is decomposed into a rigid rotational part and an elastic part. The distance field interpolation method is modified so that the interpolation is done in correlation with the warp function. The method provides the animator with a technique that can be used to create a set of models forming a smooth transition between pairs of a given sequence of keyframe models. The advantage of the new approach is that it is capable of morphing between objects having a different topological genus where no correspondence between the geometric primitives of the models needs to be established. The desired correspondence is defined by an animator in terms of a relatively small number of anchor points
Constraint-based tools for building user interfaces
Authors: Borning Alan , Duisberg Robert
Published: July 2002

A constraint describes a relation that must be maintained. Constraints provide a useful mechanism to aid in the construction of interactive graphical user interfaces. They can be used to maintain consistency between data and a view of the data, to maintain consistency among multiple views, to specify layout, and to specify relations between events and responses for describing animations of interactive systems and event-driven simulations. Object-oriented techniques for constraint representation and satisfaction are presented, and a range of examples that demonstrate the practical use of static and temporal constraints for such purposes is presented. These examples include animations of algorithms and physics simulations, and constructing user-interface elements such as file browsers, views onto statistical data, and an interactive monitor or a simulated operating system.
WYSIWIS revised: early experiences with multiuser interfaces
Authors: Stefik M. , Bobrow D. G. , Foster G. , Lanning S. , Tatar D.
Published: July 2002

WYSIWIS (What You See Is What I See) is a foundational abstraction for multiuser interfaces that expresses many of the characteristics of a chalkboard in face-to-face meetings. In its strictest interpretation, it means that everyone can also see the same written information and also see where anyone else is pointing. In our attempts to build software support for collaboration in meetings, we have discovered that WYSIWIS is crucial, yet too inflexible when strictly enforced. This paper is about the design issues and choices that arose in our first generation of meeting tools based on WYSIWIS. Several examples of multiuser interfaces that start from this abstraction are presented. These tools illustrate that there are inherent conflicts between the needs of a group and the needs of individuals, since user interfaces compete for the same display space and meeting time. To help minimize the effect of these conflicts, constraints were relaxed along four key dimensions of WYSIWIS: display space, time of display, subgroup population, and congruence of view. Meeting tools must be designed to support the changing needs of information sharing during process transitions, as subgroups are formed and dissolved, as individuals shift their focus of activity, and as the group shifts from multiple parallel activities to a single focused activity and back again.