bluuebunny/crossref_metadata_2025 huggingface dataset:
SHAPE DESCRIPTION AND INVARIANT RECOGNITION EMPLOYING CONNECTIONIST APPROACH
Authors: BEN-ARIE JEZEKIEL , WANG ZHIQIAN
Published: July 2002

This paper presents a new approach for shape description and invariant recognition by geometric-normalization implemented by neural networks. The neural system consists of a shape description network, a normalization network and a recognition stage based on fuzzy pyramidal neural networks. The description network uses a novel approach for hierarchical shape segmentation and representation which expands the image shapes into localized feature tokens. These feature tokens form a compact description of the shape and its components that include information on their location, size and orientation. The description network, which is composed of a novel pyramidal architecture called the Vectorial Gradual Lattice Pyramid, processes in parallel a new vectorial scale space representation of the shape. A novel measure called Cancellation Energy is used to determine the feature tokens. The normalization network utilizes the location, size and orientation information in the feature tokens to geometric-normalize the shape or its components with respect to these parameters. The recognition network which has a pyramidal structure, uses a fuzzy representation of these normalized feature tokens to achieve robust invariant recognition. Experimental results demonstrate robust recognition in large variations of scale, rotation, translation and also in moderate affine transformations and partial occlusion.
BIFURCATION CONTROL: THEORIES, METHODS, AND APPLICATIONS
Authors: CHEN GUANRONG , MOIOLA JORGE L. , WANG HUA O.
Published: July 2002

Bifurcation control deals with modification of bifurcation characteristics of a parameterized nonlinear system by a designed control input. Typical bifurcation control objectives include delaying the onset of an inherent bifurcation, stabilizing a bifurcated solution or branch, changing the parameter value of an existing bifurcation point, modifying the shape or type of a bifurcation chain, introducing a new bifurcation at a preferable parameter value, monitoring the multiplicity, amplitude, and/or frequency of some limit cycles emerging from bifurcation, optimizing the system performance near a bifurcation point, or a combination of some of these objectives. This article offers an overview of this emerging, challenging, stimulating, and yet promising field of research, putting the main subject of bifurcation control into perspective.
OBSTRUCTION TO DETERMINISTIC MODELING OF CHAOTIC SYSTEMS WITH AN INVARIANT SUBSPACE
Authors: LAI YING-CHENG , GREBOGI CELSO
Published: July 2002

A natural process can be deterministically modeled if solutions from its mathematical model stay close to the ones produced by nature. The mathematical model, however, is not exact due to imperfections of the natural system. We describe, in this paper, that there exists a class of models of chaotic processes, for which severe obstruction to deterministic modeling may arise. In particular, such obstruction may occur when unstable periodic orbits embedded in the chaotic invariant set have a distinct number of unstable directions, a type of nonhyperbolicity called unstable-dimension variability. We make these ideas concrete by investigating a class of deterministic models: chaotic systems with an invariant subspace such as systems of coupled chaotic oscillators. We show that unstable-dimension variability can occur in wide parameter regimes of these systems. The implications of our results to scientific modeling are discussed.
ON THE BEHAVIOR OF A SELF-EXCITING FARADAY DISK HOMOPOLAR DYNAMO WITH BATTERY IN THE PRESENCE OF AN EXTERNAL MAGNETIC FIELD
Authors: MOROZ IRENE M.
Published: July 2002

Goldbrum et al. [2000] investigated the biasing effects of including an external battery on the behavior of a self-exciting Faraday disk homopolar dynamo, originally introduced by Hide et al. [1996]. In this paper we return to the model of Hide [1997] and consider the additional effects of incorporating an external magnetic field on the dynamo.
THE HISTORIC–STOCHASTIC STRATEGIST
Authors: ALONSO-SANZ RAMÓN , MARTÍN M. CARMEN , MARTÍN MARGARITA
Published: July 2002

The basic aim of this paper is to extend earlier work on assessing the effect of considering previous results (history) in the evolutionary dynamics of the spatial formulation of the Prisoner's Dilemma when players follow one-dimensional strategies. The historic strategist models considered before were deterministic, so the choices were fixed by the strategies in an automatic way. In the present work the strategies do not fix the choices but their probabilities. Both synchronous and asynchronous updating schemes have been taken into account. It is concluded here that the essential results found in the deterministic scenario remain valid in a probabilistic context: historic memory tends to favor the main features of the initial scenario.
THE HISTORIC PRISONER'S DILEMMA
Authors: ALONSO-SANZ RAMÓN
Published: July 2002

The effect of considering previous results (history) in the spatial formulation of the Prisoner's Dilemma is assessed. It is concluded that history protects homogeneous populations against the irruption of mutant behavior.
TRANSIENT TIME IN UNIDIRECTIONAL SYNCHRONIZATION
Authors: SANTOBONI GIOVANNI , BISHOP STEVEN R. , VARONE ALBERTO
Published: July 2002

We consider here the behavior of a dynamical system consisting of two unidirectionally coupled Duffing oscillators. Under certain conditions the subsystems may become synchronized corresponding to a stable invariant subset of the full dimensional phase space. The distribution for the transient time that trajectories take to converge onto the synchronized state is investigated via numerical simulations. Some initial conditions undergo a very long transient motion distinct from the drive, before synchronization occurs. The dependence of this time on the governing system parameters and on the initial conditions of the driving system is discussed.
MULTIAGENT SYSTEMS ENGINEERING
Authors: DELOACH SCOTT A. , WOOD MARK F. , SPARKMAN CLINT H.
Published: July 2002

This paper describes the Multiagent Systems Engineering (MaSE) methodology. MaSE is a general purpose, methodology for developing heterogeneous multiagent systems. MaSE uses a number of graphically based models to describe system goals, behaviors, agent types, and agent communication interfaces. MaSE also provides a way to specify architecture-independent detailed definition of the internal agent design. An example of applying the MaSE methodology is also presented.
INCREMENTAL SCENARIO MODELING USING HIERARCHICAL OBJECT-ORIENTED PETRI NET
Authors: HONG JANG-EUI , BAE DOO-HWAN
Published: July 2002

Scenario-based modeling is emerging as a key technology in software development because scenarios are easy to describe and understand, naturally describing the real world, and highly used in several development phases. Scenario-Based Software Modeling (SBSM) represents scenarios with a formal method, and then integrates each scenario into a global one excluding redundant, incomplete, and inconsistent elements. An issue which is not yet proposed a clear solution in SBSM is the handling of different abstraction levels. In the existing proposals, this problem is hidden with an implicit assumption that all such scenarios have the same abstraction levels, which we believe to be unrealistic. In our research, we propose a Hierarchical Object-Oriented Petri Net (HOONet) as a method to specify the scenarios, and also suggest a method to integrate scenarios including different abstraction levels as well as redundancy, incompleteness, and inconsistency. Coordinating abstraction levels of scenarios can be achieved by considering scenario models as state-based transition models and verifying the transition models with respect to behavioral equivalence. In order to show the effectiveness of our suggestion, overall processes of SBSM using HOONet are explained with a practical example.
ON INFINITESIMAL STABILITY AND HOMOGENIZATION OF LINEARLY ELASTIC PERIODIC COMPOSITES
Authors: BARAŃSKI W.
Published: July 2002

This paper is devoted to the study of infinitesimal stability of linearly elastic periodic composites. A solution of the homogenization problem of infinitesimal stability with respect to Dirichlet's boundary conditions is found. Under some regularity assumptions, it is shown that in this case homogenization commutes with infinitesimal stability. The obtained results are derived in a sequence of steps involving analysis of mutual relations between H-measures, ellipticity, infinitesimal stability and the existence of modes of infinitesimal buckling.
DIRECT AND INVERSE APPROXIMATION THEOREMS FOR THE p-VERSION OF THE FINITE ELEMENT METHOD IN THE FRAMEWORK OF WEIGHTED BESOV SPACES PART II: OPTIMAL RATE OF CONVERGENCE OF THE p-VERSION FINITE ELEMENT SOLUTIONS
Authors: BABUŠKA IVO , GUO BENQI
Published: July 2002

This is the second of a series devoted to the direct and inverse approximation theorems of the p-version of the finite element method in the framework of the weighted Besov spaces. In this paper, we combine the approximability of singular solutions in the Jacobi-weighted Besov spaces, which were analyzed in the previous paper,4 with the technique of partition of unity in order to prove the optimal rate of convergence of the p-version of the finite element method for elliptic boundary value problems on polygonal domains.
LEARNING DECISION FUNCTIONS IN THE FUZZY γ-MODELS
Authors: CHIANG JUNG-HSIEN
Published: July 2002

In this approach, we investigate the fuzzy γ-models for decision analysis and making. This methodology utilizes fuzzy γ-model as an information aggregation operator. It provides several advantages due to the fact that the input to each model is the evidence supplied by the degree of satisfaction of sub-criteria and the output is the aggregated evidence. We also generalize fuzzy γ-models as a hierarchical network in this work. Thus, the decision making process is to aggregate and propagate the evidence information through such a hierarchical network. This trainable network is able to perceive and interpret complex decisions by using those fuzzy models. The simulation study examines the learning behaviors of the fuzzy γ-models using two numerical examples.
TRANSFORMING SUPERVISED CLASSIFIERS FOR FEATURE EXTRACTION (EXTENDED VERSION)
Authors: BURSTEINAS BORISAS , LONG JAMES ALLEN
Published: July 2002

Supervised feature extraction is used in data dassification and, unlike unsupervised feature extraction, uses class labels to evaluate the quality of the extracted features. It can be computationally inefficient to perform exhaustive searches to find optimal subsets of features. This article proposes an algorithm of supervised linear feature extraction based on the use of multivariate decision trees. The main motivation in proposing this new approach to feature extraction is to decrease computation time required to induce new classifiers required to evaluate every new subset of features. The new feature extraction algorithm proposed here uses an approach similar to the wrapper model method used in feature selection. In order to evaluate the performance of proposed algorithm, several tests with real world data have been performed. The fundamental importance of this new feature extraction method is found in its ability to significantly reduce computational time required to extract features from large database.
Characterization of composite knots with 1-bridge genus two
Authors: Morimoto Kanji
Published: July 2002

In the present paper, we characterize the knot types of composite knots in the 3-sphere S3 with 1-bridge genus two.
A NOTE ON THE UTILITY OF KAUFFMAN'S STATE SUMMATION FORMULA FOR THE BRACKET POLYNOMIAL
Authors: ISIHARA PAUL , KOENIGSBERG ANDREA
Published: July 2002

Kauffman's state summation formula is especially useful for computing the bracket polynomials of projection diagrams which are related by smoothings or crossing changes. This facilitates the writing of a symbolic algebra program which computes the normalized bracket polynomials and frequencies of knots and links whose projection diagrams result from a given knot's oriented projection diagram either by crossing changes or by orientation preserving smoothings called natural smoothings. These frequencies provide insight into the unknotting game (and similar resultant games) whose object is to specify crossing changes or natural smoothings that will transform a given projection diagram of a knot into a projection diagram representing an unknot (or some other specified knot or link). The practical utility of the state summation formula is greatly enhanced by means of diagrams for closed tangle sums. These diagrams offer a special cost-reducing method to obtain crucial information needed to compute the state summation formula. This special method also gives insight into why the bracket is unchanged by mutation and contributes a strategy to the enigmatic search for a non-trivial knot with Jones polynomial equal to one.
ON THE SIZE OF LINKS IN Kn, n, Kn, n, 1, AND Kn
Authors: JOHNSON BRENDA , JOHNSON WILLIAM
Published: July 2002

For all n ≥ 4, and all even 4 ≤ s, t ≤ 2n - 4 with s + t = 2n, we show that every spatial embedding of Kn, n contains a non-trivial link involving and s-cycle and a t-cycle. We use this result to prove that for all n ≥ 3, 3 ≤ u, v ≤ 2n - 2 with u + v = 2n + 1, every spatial embedding of Kn, n, 1 has a non-trivial link involving a u-cycle and a v-cycle. These results imply that every embedding of Kn, for n ≥ 4, has non-trivial links of all possible sizes.
A CONSTANT EQUATION OF STATE FOR QUINTESSENCE?
Authors: DI PIETRO ELISA , DEMARET JACQUES
Published: July 2002

Quintessence is often invoked to explain the universe's acceleration suggested by type Ia supernovae observations. The aim of this letter is to study the validity of using a constant equation of state for quintessence models. We shall show that this hypothesis strongly constraint the form of the scalar potential.
THE PROPERTIES OF STRANGE STARS IN THE QUARK MASS– DENSITY–DEPENDENT MODEL
Authors: BENVENUTO O. G. , LUGONES G.
Published: July 2002

We study the general properties of compact objects made up of strange matter in the framework of a new equation of state in which the quark masses are parametrized as functions of the baryon density, so that they are heavy (light) at low (high) densities. This has been called the "quark mass-density-dependent model." In this approximation, the strange matter equation of state is rather similar to the corresponding to the MIT Bag Model, but it is significantly stiffer at low densities. Such a property modifies the structure of strange stars in a sizeable way.

In this framework, we calculate the structure of strange stars (mass, radius, central density, gravitational redshift, moment of inertia, and total baryon number) finding that the resulting structures are rather similar to those obtained in the MIT Bag model, although some important differences appear. Comparing to the standard bagged case (with a bag constant in the range of B = 60 - 80 MeV fm-3), we find that these objects may be more massive and may show gravitational redshifts larger (up to ≈ 10%) than in the bag case. The moment of inertia and total baryon number may be larger than in the bagged case up to a factor of three.

We also calculate the first three radial pulsation modes of these objects, finding that the relation of period vs. gravitational redshift is rather similar to the bag case. Also, we present an analytical treatment for such modes in the low-mass strange stars regime, which is in reasonable agreement with the numerical results.
LONGEVITY AND HIGHEST-ENERGY COSMIC RAYS
Authors: FRAMPTON PAUL H. , KESZTHELYI BETTINA , NG Y. JACK
Published: July 2002

It is proposed that the highest energy ~1020 eV cosmic ray primaries are protons which are decay products of a superheavy particle, G. The protons may be decay products either directly of a nearby (galactic) Gor of a long-lived intermediate particle X which arises from decay of a distant (cosmological) G, then decays in or near our Galaxy. Such scenarios can occur in e.g. SU(15) grand unification and in some preon models.
DISCONTINUOUS POINT PROCESSES FOR THE ANALYSIS OF REPAIRABLE UNITS
Authors: CALABRIA RAFFAELA , PULCINI GIANPAOLO
Published: July 2002

In this paper, a useful family of discontinuous point processes is proposed, which is able to analyze the failure pattern of repairable units subjected to repair actions that depart from the commonly assumed minimal repair policy. Maximum likelihood estimators of the parameters which index two special cases of the above family are derived, and procedures for testing the departure from the minimal repair assumption, based on asymptotic results, are discussed. An exact and unbiased testing procedure to be performed for small or moderate sample sizes is also proposed. Finally, numerical examples are given to illustrate the proposed estimation and testing procedures.
ELECTRONIC BAND STRUCTURE OF STEPPED Si(100) SURFACES
Authors: SALMAN SAED A. , KATIRCIOĞLU ŞENAY , ERKOÇ ŞAKIR
Published: July 2002

We have investigated the electronic band structure of five different stepped Si(100) surfaces by the empirical tight binding (ETB) method. It has been found that the interaction states have approximately the same energy values for the stepped surfaces with a similar dimer bond nature on the terraces. The single layer stepped models show different density-of-states features than the double layer stepped models.
OXIDE LAYER FORMED ON THE SURFACE OF OZONE-TREATED InP
Authors: FATTAH GAMAL ABDEL
Published: July 2002

Oxides are formed on InP substrates under UV/ozone illumination. The thickness of the formed oxides increases as the exposure time to the UV source increases, and tends to saturate after three hours of exposure. The optical transmission and X-ray diffraction measurements predict the formation of the oxide layer. X-ray diffraction shows that the oxide film is a mixture of In 2 O 3 and InPO 4 and seems to be In 2 O 3-rich. The integrated absorption coefficient of the formed oxide layer does not depend on the wavelengths in the range of 800–1400 nm, and is found to be in the order of 107 cm-1. The reflections from the sample surface after UV/ozone oxidation at different exposure times are also measured.
QUANTITATIVE STUDY OF THERMAL DIFFUSION OF ELEMENTS ACROSS A ZnSe/GaAs INTERFACE USING SIMS
Authors: GARD F. S. , RILEY J. D. , LECKEY R. , USHER B. F. , PRINCE K. , BURKE P.
Published: July 2002

ZnSe epilayers were grown on GaAs substrates, which had been treated with Se and Zn prior to the growth process. Thermal diffusion of elements across the interface was investigated, using secondary ion mass spectroscopy (SIMS). Ion-implanted standards have been used to calculate the "useful ion yield" for Zn and Se in the GaAs matrix and for Ga and As in the ZnSe matrix. Consequently, SIMS raw data were converted to quantified data. Diffusion of Ga atoms across the interface was observed for Zn-pretreated substrates. A comparison study showed that Se pretreatment of the GaAs substrate prevents thermal diffusion of Ga across the interface. This effect is believed to be due to the formation of GaAs x Se y layers at the interface, which acts as a barrier to diffusion. The Ga diffusion coefficients at annealing temperatures of 400°C, 500°C and 600°C were found to be 2.1×10-16 cm 2/s, 1.9×10-15 cm 2/s and 2.2×10-14 cm -2/s, respectively. The thermal diffusion of other elements across the interface was not observed within the resolution limit of SIMS analysis.
ADSORPTION OF WATER ON SINGLE AND DOUBLE LAYER STEPPED Si(100) SURFACES
Authors: KATIRCIOĞLU ŞENAY , SALMAN SAED A. , ERKOC SAKIR
Published: July 2002

We have investigated possible water adsorption forms on SA , DA and DB type stepped Si(100) surfaces. Calculations are performed using the empirical tight binding method. Two types of adsorption models of water on stepped Si(100) surfaces have been considered: the dissociative type (H, OH) and the molecular type ( H2O ). The results of the density of states indicate a dissociative type of water adsorption on SA , DA and DB type stepped Si(100) surfaces.
IN SITU PHOTOLUMINESCENCE STUDIES OF SILICON SURFACES DURING PHOTOELECTROCHEMICAL ETCHING PROCESSES
Authors: LIU FENG-MING , REN BIN , YAN JIA-WEI , MAO BING-WEI , TIAN ZHONG-QUN
Published: July 2002

The photoluminescence (PL) from silicon surfaces during photoelectrochemical etching processes was monitored in situ by using a confocal microprobe spectrometer. The etching time, laser power, polarization potential and the resistance of silicon were found to remarkably influence the formation of porous silicon (PS). For the high resistance silicon sample, the PL band intially increases in intensity and blueshifts with the progress of etching, then decreases and stops shifting. The higher the laser power is, the stronger the PL intensity and the shorter the wavelength could be. For the low resistance silicon sample, no clear shift in the wavelength could be found with the progress of etching. These results were interpreted by the quantum confinement effect together with the influence of electrochemical reaction equilibrium and the surface oxidation species on the formation of PS.
FIRST PRINCIPLES TOTAL ENERGY STUDY OF THE MORPHOLOGICAL INSTABILITY OF Mo(111) INDUCED BY ULTRATHIN FILMS OF Rh
Authors: HUANG D. Y. , JIANG P. , CHE J. G. , ZHANG K. M. , XIE X. D.
Published: July 2002

By using first principles total energy calculations, the surface energies of (100), (110), (111) and (211) surfaces of Mo before and after adsorbing ultrathin films of Rh have been presented. The results show that in the case of clean Mo surfaces Mo(111) is stable against faceting to Mo(211), Mo(110) and Mo(100), while after adsorbing one physical monolayer of Rh, the surface energies of all the four surfaces decrease, and Mo(111) can facet to {211}, but not to {110} and {100} surfaces.
RENORMALIZED LAPLACIANS ON A CLASS OF HILBERT MANIFOLDS AND A BOCHNER–WEITZENBÖCK TYPE FORMULA FOR CURRENT GROUPS
Authors: ARNAUDON MARC , BELOPOLSKAYA YANA , PAYCHA SYLVIE
Published: July 2002

We define renormalized Laplacians and investigate their properties for a class of C2 functions on Hilbert manifolds modeled on a Hilbert space Hs(M, V) of sections of Sobolev class Hs of some vector bundle V based on a closed Riemannian manifold M, and such that the transition maps of the Hilbert manifold are pseudo-differential operators acting on smooth sections of the bundle V. Among these manifolds we find current groups Hs(M, G), s> dim M/2 where M is a closed manifold and G a Lie group.

Weighted Laplacians are renormalized Laplacians which coincide with ordinary Laplacians when the underlying manifold M reduces to a point. We prove a Bochner–Weitzenböck type formula for weighted Laplacians and we point out how in some cases it can reduce to a relation of the type [Δ,∇]f= Ricci (∇f, ·) for a class of functions on certain current groups.

Another type of renormalized Laplacian we define are Lévy-type Laplacians which coincide with Lévy Laplacians when the underlying manifold M is one-dimensional. We describe them as limit generators for a one-parameter family of regularized Brownian motions.
COALITION CABINETS IN JAPAN (1993–1997): A GAME THEORY ANALYSIS
Authors: ONO RIE , MUTO SHIGEO
Published: July 2002

In this paper, we analyse three Japanese coalition cabinets organised since July 1993, by evaluating parties' power for possible alternative cabinets with Owen's coalition value. In these cabinets, certain parties played a crucial role to determine the cabinet coalition structure. The analysis shows that each of these parties made a good decision for itself in terms of the coalition value, and that the value can be a good prediction of party power.
FREE VIBRATIONS OF SHEAR DEFORMABLE CIRCULAR CURVED BEAMS RESTING ON ELASTIC FOUNDATIONS
Authors: LEE BYOUNG KOO , OH SANG JIN , PARK KWANG KYOU
Published: July 2002

The governing differential equations for the out-of-plane, free vibration of circular curved beams resting on elastic foundations are derived and solved numerically. The formulation takes into consideration the effects of rotary inertia and transverse shear deformation. The lowest three natural frequencies are calculated for beams with hinged–hinged, hinged-clamped, and clamped–clamped end constraints. The effects of various system parameters as well as rotary inertia and shear deformation on the natural frequencies are investigated.
1/F NOISE, THE MEASUREMENT OF TIME AND NUMBER THEORY
Authors: PLANAT MICHEL
Published: July 2002

Time and frequency measurements of a high frequency oscillator need the comparison to a reference oscillator: the physical units of the measurement are the integers and the relevant approach is analytical number theory. We show this in the context of the moon-sun calendar discovered in ancient Greece and in the context of a communication receiver. It is shown that the resets in time measurements are governed by continued fraction expansions and that their low frequency statistics connects to prime number theory. A link between Riemann hypothesis and 1/F noise arises in this context.
THE EVOLUTION OF INDUSTRIAL CLUSTERS — SIMULATING SPATIAL DYNAMICS
Authors: BRENNER THOMAS , WEIGELT NIELS
Published: July 2002

Industrial clusters have received much attention in economic research in the last decade. They are seen as one of the reasons for the economic success of certain regions in comparison to others. This paper studies the evolution of such industrial clusters. To this end, a spatial structure of regions is set up and the entry, exit, and growth of firms within these regions is modelled and studied with the help of simulations. We are able to obtain some knowledge about the basic characteristics of this dynamic process and about the spatial relation between industries that results. It is shown that it matters whether one or the other industry appears first and that location of clusters of one industry influence the location of other industries. Furthermore, some necessary conditions for the evolution of industrial clusters are identified.
From Neurons to Brain: Adaptive Self-Wiring of Neurons
Authors: Segev Ronen , Ben-Jacob Eshel
Published: July 2002

During embryonic morphogenesis, a collection of individual neurons turns into a functioning network with unique capabilities. Only recently has this most staggering example of emergent process in the natural world, began to be studied. Here we propose a navigational strategy for neurites growth cones, based on sophisticated chemical signaling. We further propose that the embryonic environment (the neurons and the glia cells) acts as an excitable media in which concentric and spherical chemical waves are formed. Together with the navigation strategy, the chemical waves provide a mechanism for communication, regulation, and control required for the adaptive self-wiring of neurons.
AN AUTOMATED 3D FACILITIES PLANNING AND OPERATIONS MODEL GENERATOR FOR SYNTHESIZING GENERIC MANUFACTURING OPERATIONS IN VIRTUAL REALITY
Authors: CHAWLA RAVI , BANERJEE AMARNATH
Published: July 2002

One of the basic building blocks in virtual manufacturing is a 3D facility. An automated method for reconstructing a 3D facility from a 2D layout is presented here. The 3D facility is reconstructed using spacefilling curves (SFC), and simultaneously creating hierarchy levels within a scenegraph structure, which is a directed acyclic graph (DAG). An iterative process is used to acquire knowledge about the layout, and reorganize the scenegraph structure based on the acquired knowledge, and cell formation within the layout. Additional CAD data models for the equipment within the facility provide depth within the scenegraph framework to synthesize generic manufacturing operations, such as load, unload, move and process, in a virtual manufacturing environment. The objects within the 3D facility have been modified to provide the links required for synthesizing the generic manufacturing operations in the virtual manufacturing environment. The generic manufacturing operations are realized by updating the hierarchy links between the manufacturing resources and the parts being produced, within the scenegraph framework. An example is provided to illustrate the use of the proposed reconstruction method.
A reference architecture for the component factory
Authors: Basili Victor R. , Caldiera Gianluigi , Cantone Giovanni
Published: July 2002

Software reuse can be achieved through an organization that focuses on utilization of life cycle products from previous developments. The component factory is both an example of the more general concepts of experience and domain factory and an organizational unit worth being considered independently. The critical features of such an organization are flexibility and continuous improvement. In order to achieve these features we can represent the architecture of the factory at different levels of abstraction and define a reference architecture from which specific architectures can be derived by instantiation. A reference architecture is an implementation and organization independent representation of the component factory and its environment. The paper outlines this reference architecture, discusses the instantiation process, and presents some examples of specific architectures by comparing them in the framework of the reference model.
DAIDA
Authors: Jarke M. , Mylopoulos J. , Schmidt J. W. , Vassiliou Y.
Published: July 2002

We present a framework for the development of information systems based on the premise that the knowledge that influences the development process needs to somehow be captured, represented, and managed if the development process is to be rationalized. Experiences with a prototype environment developed in ESPRIT project DAIDA demonstrate the approach. The project has implemented an environment based on state-of-the-art languages for requirements modeling, design and implementation of information systems. In addition, the environment offers tools for aiding the mapping process from requirements to design and then to implementation, also for representing decisions reached during the development process. The development process itself is represented explicitly within the system, thus making the DAIDA development framework easier to comprehend, use, and modify.
Sparse dynamic programming II
Authors: Eppstein David , Galil Zvi , Giancarlo Raffaele , Italiano Giuseppe F.
Published: July 2002

Dynamic programming solutions to two recurrence equations, used to compute a sequence alignment from a set of matching fragments between two strings, and to predict RNA secondary structure, are considered. These recurrences are defined over a number of points that is quadratic in the input size; however, only a sparse set matters for the result. Efficient algorithms are given for solving these problems, when the cost of a gap in the alignment or a loop in the secondary structure is taken as a convex or concave function of the gap or loop length. The time complexity of our algorithms depends almost linearly on the number of points that need to be considered; when the problems are sparse, this results in a substantial speed-up over known algorithms.
The cost of conservative synchronization in parallel discrete event simulations
Authors: Nicol David M.
Published: July 2002

This paper analytically studies the performance of a synchronous conservative parallel discrete-event simulation protocol. The class of models considered simulates activity in a physical domain, and possesses a limited ability to predict future behavior. Using a stochastic model, it is shown that as the volume of simulation activity in the model increases relative to a fixed architecture, the complexity of the average per-event overhead due to synchronization, event list manipulation, lookahead calculations, and processor idle time approaches the complexity of the average per-event overhead of a serial simulation, sometimes rapidly. The method is therefore within a constant factor of optimal. The result holds for the worst case “fully-connected” communication topology, where an event in any other portion of the domain can cause an event in any other protion of the domain. Our analysis demonstrates that on large problems—those for which parallel processing is ideally suited— there is often enough parallel workload so that processors are not usually idle. It also demonstrated the viability of the method empirically, showing how good performance is achieved on large problems using a thirty-two node Intel iPSC/2 distributed memory multiprocessor.
A selective undo mechanism for graphical user interfaces based on command objects
Authors: Berlage Thomas
Published: July 2002

It is important to provide a recovery operation for applications with a graphical user interface. A restricted linear undo mechanism can conveniently be implemented using object-oriented techniques. Although linear undo provides an arbitrarily long history, it is not possible to undo isolated commands from the history without undoing all following commands. Various undo models have been proposed to overcome this limitation, but they all ignore the problem that in graphical user interfaces a previous user action might not have a sensible interpretation in another state.

Selective undo
introduced here can undo isolated commands by copying them into the current state “
if that is meaningful.”
Furthermore, the semantics of selective undo are argued to be more natural for the user, because the mechanism only looks at the command to undo and the current state and does not depend on the history in between. The user interface for selective undo can also be implemented generically. Such a generic implementation is able to provide a consistent recovery mechanism in arbitrary applications.
Computing hyperelliptic integrals for surface measure of ellipsoids
Authors: Dunkl Charles F. , Ramirez Donald E.
Published: July 2002

An algorithm for computing a class of hyperelliptic integrals and for determining the surface measure of ellipsoids is described. The algorithm is used to construct an omnibus optimal-design criterion.
Algorithm 737: INTLIB—a portable Fortran 77 interval standard-function library
Authors: Kearfott R. B. , Dawande M. , Du K. , Hu C.
Published: July 2002

INTLIB is meant to be a readily available, portable, exhaustively documented interval arithmetic library, written in standard Fortran 77. Its underlying philosophy is to provide a standard for interval operations to aid in efficiently transporting programs involving interval arithmetic. The model is the BLAS package, for basic linear algebra operations. The library is composed of elementary interval arithmetic routines, standard function routines for interval data and values, and utility routines. The library can be used with INTBIS (Algorithm 681), and a Fortran 90 module to use the library to define an interval data type is available from the first author.
Applying Bayesian networks to information retrieval
Authors: Fung Robert , Del Favero Brendan
Published: July 2002

Information retrieval (IR) is the identification of documents or other units of information in a collection that are relevant to a particular information need. An information need is a set of questions to which someone would like to find an answer. Here are some examples of IR tasks: finding articles in the New York
Times
that discuss the Iran-Contra affair; searching the recent postings in a Usenet newsgroup for references to a particular model of personal computer; finding the entries referring to butterflies in an online CD-ROM encyclopedia.
Incremental computation of nested relational query expressions
Authors: Baekgaard Lars , Mark Leo
Published: July 2002

Efficient algorithms for incrementally computing nested query expressions do not exist. Nested query expressions are query expressions in which selection/join predicates contain subqueries. In order to respond to this problem, we propose a two-step strategy for incrementaly computing nested query expressions. In step (1), the query expression is transformed into an equivalent unnested flat query expression. In step (2), the flat query expression is incrementally computed. To support step (1), we have developed a very concise algebra-to-algebra transformation algorithm, and we have formally proved its correctness. The flat query expressions resulting from the transformation make intensive use of the relational set-difference operator. To support step (2), we present and analyze an efficient algorithm for incrementally computing set differences based on view pointer caches. When combined with existing incremental algorithms for SPJ queries, our incremental set-difference algorithm can be used to compute the unnested flat query expressions efficiently. It is important to notice that without our incremental set-difference algorithm the existing incremental algorithms for SPJ queries are useless for any query involving the set-difference operator, including queries that are not the result of unnesting nested queries.
Scalable concurrent counting
Authors: Herlihy Maurice , Lim Beng-Hong , Shavit Nir
Published: July 2002

The notion of counting is central to a number of basic multiprocessor coordination problems, such as dynamic load balancing, barrier synchronization, and concurrent data structure design. We investigate the scalability of a variety of counting techniques for large-scale multiprocessors. We compare counting techniques based on: (1) spin locks, (2) message passing, (3) distributed queues, (4) software combining trees, and (5) counting networks. Our comparison is based on a series of simple benchmarks on a simulated 64-processor Alewife machine, a distributed-memory multiprocessor currently under development at MIT. Although locking techniques are known to perform well on small-scale, bus-based multiprocessors, serialization limits performance, and contention can degrade performance. Both counting networks and combining trees outperform the other methods substantially by avoiding serialization and alleviating contention, although combining-tree throughput is more sensitive to variations in load. A comparison of shared-memory and message-passing implementations of counting networks and combining trees shows that message-passing implementations have substantially higher throughput.
Algorithm 756: a MATLAB toolbox for Schwarz-Christoffel mapping
Authors: Driscoll Tobin A.
Published: July 2002

The Schwarz-Christoffel transformation and its variations yield formulas for conformal maps from standard regions to the interiors or exteriors of possibly unbounded polygons. Computations involving these maps generally require a computer, and although the numerical aspects of these transformations have been studied, there are few software implementations that are widely available and suited for general use. The Schwarz-Christoffel Toolbox for MATLAB is a new implementation of Schwarz-Christoffel formulas for maps from the disk, half-plane, strip, and rectangle domains to polygon interiors, and from the disk to polygon exteriors. The toolbox, written entirely in the MATLAB script language, exploits the high-level functions, interactive environment, visualization tools, and graphical user interface elements supplied by current versions of MATLAB, and is suitable for use both as a standalone tool and as a library for applications written in MATLAB, Fortran, or C. Several examples and simple applications are presented to demonstrate the toolbox's capabilities.
The Manchester prototype dataflow computer
Authors: Gurd J. R , Kirkham C. C , Watson I.
Published: July 2002

The Manchester project has developed a powerful dataflow processor based on dynamic tagging. This processor is large enough to tackle realistic applications and exhibits impressive speedup for programs with sufficient parallelism.
Constraint tightness and looseness versus local and global consistency
Authors: van Beek Peter , Dechter Rina
Published: July 2002

Constraint networks are a simple representation and reasoning framework with diverse applications. In this paper, we identify two new complementary properties on the restrictiveness of the constraints in a network—
constraint tightness
and
constraint looseness
—and we show their usefulness for estimating the level of local consistency needed to ensure global consistency, and for estimating the level of local consistency present in a network. In particular, we present a sufficient condition, based on constraint tightness and the level of local consistency, that guarantees that a solution can be found in a backtrack-free manner. The condition can be useful in applications where a knowledge base will be queried over and over and the preprocessing costs can be amortized over many queries. We also present a sufficient condition for local consistency, based on constraint looseness, that is straightforward and inexpensive to determine. The condition can be used to estimate the level of local consistency of a network. This in turn can be used in deciding whether it would be useful to preprocess the network before a backtracking search, and in deciding which local consistency conditions, if any, still need to be enforced if we want to ensure that a solution can be found in a backtrack-free manner. Two definitions of local consistency are employed in characterizing the conditions: the traditional variable-based notion and a recently introduced definition of local consistency called
relational consistency
.
Algorithm 769
Authors: Pardalos Panos M. , Pitsoulis Leonidas S. , Resende Mauricio G. C.
Published: July 2002

We describe Fortran subroutines for finding approximate solutions of sparse instances of the Quadratic Assignment Problem (QAP) using a Greedy Randomized Adaptive Search Procedure (GRASP). The design and implementation of the code are described in detail. Computational results comparing the new subroutines with a dense version of the code (Algorithm 754, ACM TOMS) show that the speedup increases with the sparsity of the data.
In black and white
Authors: Chen Huo Yan , Tse T. H. , Chan F. T. , Chen T. Y.
Published: July 2002

Because of the growing importance of object-oriented programming, a number of testing strategies have been proposed. They are based either on pure black-box or white-box techniques. We propose in this article a methodology to integrate the black- and white-box techniques. The black-box technique is used to select test cases. The white-box technique is mainly applied to determine whether two objects resulting from the program execution of a test care are observationally equivalent. It is also used to select test cases in some situations. We define the concept of a fundamental pair as a pair of equivalent terms that are formed by replacing all the variables on both sides of an axiom by normal forms. We prove that an implementation is consistent with respect to all equivalent terms if and only if it is consistent with respect to all fundamental pairs. In other words, the testing coverage of fundamental pairs is as good as that of all possible term rewritings, and hence we need only concentrate on the testing of fundamental pairs. Our strategy is based on mathematical theorems. According to the strategy, we propose an algorithm for selecting a finite set of fundamental pairs as test cases. Given a pair of equivalent terms as a test case, we should then determine whether the objects that result from executing the implemented program are observationally equivalent. We prove, however, that the observational equivalence of objects cannot be determined using a finite set of observable contexts (which are operation sequences ending with an observer function) derived from any black-box technique. Hence we supplement our approach with a “relevant observable context” technique, which is a heuristic white-box technique to select a relevant finite subset of the set of observable contexts for determining the observational equivalence. The relevant observable contezxts are constructed from a data member relevance graph (DRG), which is an abstraction of the given implementation for a given specificatin. A semiautomatic tool hass been developed to support this technique.
Computing rank-revealing QR factorizations of dense matrices
Authors: Bischof Christian H. , Quintana-Ortí G.
Published: July 2002

We develop algorithms and implementations for computing rank-revealing QR (RRQR) factorizations of dense matrices. First, we develop an efficient block algorithm for approximating an RRQR factorization, employing a windowed version of the commonly used Golub pivoting strategy, aided by incremental condition estimation. Second, we develop efficiently implementable variants of guaranteed reliable RRQR algorithms for triangular matrices originally suggested by Chandrasekaran and Ipsen and by Pan and Tang. We suggest algorithmic improvements with respect to condition estimation, termination criteria, and Givens updating. By combining the block algorithm with one of the triangular postprocessing steps, we arrive at an efficient and reliable algorithm for computing an RRQR factorization of a dense matrix. Experimental results on IBM RS/6000 SGI R8000 platforms show that this approach performs up to three times faster that the less reliable QR factorization with column pivoting as it is currently implemented in LAPACK, and comes within 15% of the performance of the LAPACK block algorithm for computing a QR factorization without any column exchanges. Thus, we expect this routine to be useful in may circumstances where numerical rank deficiency cannot be ruled out, but currently has been ignored because of the computational cost of dealing with it.
Concurrency and distribution in object-oriented programming
Authors: Briot Jean-Pierre , Guerraoui Rachid , Lohr Klaus-Peter
Published: July 2002

This paper aims at discussing and classifying the various ways in which the object paradigm is used in concurrent and distributed contexts. We distinguish among the
library
approach, the
integrative
approach, and the
reflective
approach. The library approach applies object-oriented concepts, as they are, to structure concurrent and distributed systems through class libraries. The integrative approach consists of merging concepts such as object and activity, message passing, and transaction, etc. The reflective approach integrates class libraries intimately within an object-based programming language. We discuss and illustrate each of these and point out their complementary levels and goals.
Understanding and constructing shared spaces with mixed-reality boundaries
Authors: Benford Steve , Greenhalgh Chris , Reynard Gail , Brown Chris , Koleva Boriana
Published: July 2002

We propose an approach to creating shared mixed realities based on the construction of transparent boundaries between real and virtual spaces. First, we introduce a taxonomy that classifies current approaches to shared spaces according to the three dimensions of transportation, artificiality, and spatiality. Second, we discuss our experience of staging a poetry performance simultaneously within real and virtual theaters. This demonstrates the complexities involved in establishing social interaction between real and virtual spaces and motivates the development of a systematic approach to mixing realities. Third, we introduce and demonstrate the technique of mixed-reality boundaries as a way of joining real and virtual spaces together in order to address some of these problems.