ppxscal/embedding_network huggingface dataset:
Computation and Continuation of Homoclinic and Heteroclinic Orbits with Arclength Parameterization
Authors: Lixin Liu, Gerald Moore, Robert D. Russell
Venue: SIAM Journal on Scientific Computing (1997)

In this paper, we study a numerical method for the computation and continuation of homoclinic and heteroclinic orbits based upon the arclength parameterization of the orbits. Unlike most other methods, this method utilizes the geometric structure of the homoclinic and heteroclinic orbits and does not require solving a boundary value problem (BVP) on an infinite interval. However, the BVP formulated by this method can have a singularity at the end of the domain, and thus we introduce a special collocation method to handle such a singularity. We discuss the convergence properties of our collocation method and the implementation of the method which uses the software AUTO. For several examples we show that the arclength parameterization compares very favorably with the other numerical methods, although there are some limitations in the Sil'nikov case.
Fair scheduling in wireless packet networks
Authors: Songwu Lu, Vaduvur Bharghavan, Rayadurgam Srikant
Venue: ACM SIGCOMM Computer Communication Review (1997)

Fair scheduling of delay and rate-sensitive packet flows over a wireless channel is not addressed effectively by most contemporary wireline fair scheduling algorithms because of two unique characteristics of wireless media: (a) bursty channel errors, and (b) location-dependent channel capacity and errors. Besides, in packet cellular networks, the base station typically performs the task of packet scheduling for both downlink and uplink flows in a cell; however a base station has only a limited knowledge of the arrival processes of uplink flows.In this paper, we propose a new model for wireless fair scheduling based on an adaptation of fluid fair queueing to handle location-dependent error bursts. We describe an ideal wireless fair scheduling algorithm which provides a packetized implementation of the fluid model while assuming full knowledge of the current channel conditions. For this algorithm, we derive the worst-case throughput and delay bounds. Finally, we describe a practical wireless scheduling algorithm which approximates the ideal algorithm. Through simulations, we show that the algorithm achieves the desirable properties identified in the wireless fluid fair queueing model.
Bounds for the Computational Power and Learning Complexity of Analog Neural Nets
Authors: Wolfgang Maass
Venue: SIAM Journal on Computing (1997)

It is shown that high-order feedforward neural nets of constant depth with piecewise-polynomial activation functions and arbitrary real weights can be simulated for Boolean inputs and outputs by neural nets of a somewhat larger size and depth with Heaviside gates and weights from {-1, 0, 1}. This provides the first known upper bound for the computational power of the former type of neural nets. It is also shown that in the case of first-order nets with piecewise-linear activation functions one can replace arbitrary real weights by rational numbers with polynomially many bits without changing the Boolean function that is computed by the neural net. In order to prove these results, we introduce two new methods for reducing nonlinear problems about weights in multilayer neural nets to linear problems for a transformed set of parameters. These transformed parameters can be interpreted as weights in a somewhat larger neural net.As another application of our new proof technique we show that neural nets with piecewise-polynomial activation functions and a constant number of analog inputs are probably approximately correct (PAC) learnable (in Valiant's model for PAC learning [Comm. Assoc. Comput. Mach., 27 (1984), pp. 1134--1142]).
From Multiple Stereo Views to Multiple 3-D Surfaces
Authors: P. Fua
Venue: International Journal of Computer Vision (1997)

We present a framework for 3-dimensional surface reconstruction that can be used to model fully 3-D scenes from an arbitrary number of stereo views taken from vastly different viewpoints. This is a key step toward producing 3-D world-descriptions of complex scenes using stereo and is a very challenging problem: real-world scenes tend to contain many 3-D objects, they do not usually conform to the 2-1/2-D assumption made by traditional algorithms, and one cannot take it for granted that the computed 3-D points can easily be clustered into separate groups. Furthermore, stereo data is often incomplete and sometimes erroneous, which makes the problem even more difficult.By combining a particle-based representation, robust fitting, and optimization of an image-based objective function, we have been able to reconstruct surfaces without any a priori knowledge of their topology and in spite of the noisiness of the stereo data.Our current implementation goes through three steps&mdash;initializing a set of particles from the input 3-D data, optimizing their location, and finally grouping them into global surfaces. Using several complex scenes containing multiple objects, we demonstrate the competence of this method and its ability to merge information and thus to go beyond what can be done with conventional stereo alone.
Simulation of complex construction processes
Authors: Photios G. Ioannou, Julio C. Martinez
Venue: Proceedings of the 28th conference on Winter simulation (1996)

Eight successively refined simulation models for the earthmoving operations involved in the construction of a dam provide the foundation for illustrating the ease and effectiveness of modeling complex construction processes by using STROBOSCOPE, a modern simulation system based on a programming language that follows the activity-scanning paradigm. This approach and the use of characterized resources in a stochastic environment make the typical engineering calculations for heavy equipment performance relatively easy to implement and significantly more realistic and accurate.
First Order Regression
Authors: Aram Karalič, Ivan Bratko
Venue: Machine Learning (1997)

We present a new approach, called First Order Regression (FOR), to handling numerical information in Inductive Logic Programming (ILP). FOR is a combination of ILP and numerical regression. First-order logic descriptions are induced to carve out those subspaces that are amenable to numerical regression among real-valued variables. The program FORS is an implementation of this idea, where numerical regression is focused on a distinguished continuous argument of the target predicate. We show that this can be viewed as a generalisation of the usual ILP problem. Applications of FORS on several real-world data sets are described: the prediction of mutagenicity of chemicals, the modelling of liquid dynamics in a surge tank, predicting the roughness in steel grinding, finite element mesh design, and operator&lsquo;s skill reconstruction in electric discharge machining. A comparison of FORS&lsquo; performance with previous results in these domains indicates that FORS is an effective tool for ILP applications that involve numerical data.
Novel Radix Finite Field Multiplier for GF(2^m)
Authors: M. C. Mekhallalati, A. S. Ashur, M. K. Ibrahim
Venue: Journal of VLSI Signal Processing Systems (1997)

In this paper, a new {\it High-Radix} Finite Field multiplication algorithm for GF(2^m) is proposed for the first time. The proposed multiplication algorithm can operate in a Digit-serial fashion, and hence can give a trade-off between the {\it speed}, the{\it area} , the input/output pin limitation, and the low power consumption by simply {\it varying} the digit size. A detailed example of a new Radix-16 GF(2^m) Digit-Serial multiplication architecture adopting the proposed algorithm illustrates a speed improvement of 75% when compared to conventional Radix-2 bit-serial realization. This is made more significant when it is noted that the speed improvement of 75% was achieved at the expense of only 2.3 times increase in the hardware requirements of the proposed architecture.
Low-Gain Control of Uncertain Regular Linear Systems
Authors: Hartmut Logemann, Stuart Townley
Venue: SIAM Journal on Control and Optimization (1997)

It is well known that closing the loop around an exponentially stable, finite-dimensional, linear, time-invariant plant with square transfer-function matrix $\BG(s)$ compensated by a controller of the form $(k/s)\Gamma_0$, where $k\in {\Bbb R}$ and $\Gamma_0\in {\Bbb R}\mm$, will result in an exponentially stable closed-loop system which achieves tracking of arbitrary constant reference signals, provided that (i) all the eigenvalues of $\BG(0)\Gamma_0$ have positive real parts and (ii) the gain parameter $k$ is positive and sufficiently small. In this paper we consider a rather general class of infinite-dimensional linear systems, called regular systems, for which convenient representations are known to exist, both in time and in frequency domain. The purpose of the paper is twofold: (i) we extend the above result to the class of exponentially stable regular systems and (ii) we show how the parameters $k$ and $\Gamma_0$ can be tuned adaptively. The resulting adaptive tracking controllers are not based on system identification or parameter estimation algorithms, nor is the injection of probing signals required.
On-line change mechanisms: the software architectural level
Authors: Sylvia Stuurman, Jan van Katwijk
Venue: Proceedings of the 6th ACM SIGSOFT international symposium on Foundations of software engineering (1998)

Our interest in the field of software architecture is focused on the application in technical systems, such as control systems. Our current research in this field is centered around a real-life case study, a control system for unmanned vehicles transporting containers on the "Maasvlakte" , an area in the ports of Rotterdam.Important issues in this control system are scalability, evolvability, and on-line change capacities.In this paper, we discuss two mechanisms for on-line change in the distributed control system for the Maasvlakte system, which we have implemented in Java. The software architecture we use is a configuration of distributed processes, communicating according to the subscription model. We will focus on the software architectural aspects of the mechanisms for on-line change. One of these mechanisms is associated with the decoupling of processes as a result of the subscription-based communication model. The other mechanism is based on the late-binding properties of Java.
CVE'98: collaborative virtual environments 1998
Authors: Elizabeth F. Churchill, Dave Snowdon
Venue: ACM SIGGROUP Bulletin (1998)

A Collaborative Virtual Environment (CVE) is an application that uses a Virtual Environment to support human-human and human-system communication. Within such virtual environments, multiple users can convene, communicate and collaborate. Virtual Environments vary in their representational richness; for example environments may be graphical (2D or 3D) or may be purely text-based as with many MUDs/MOOs. Users are often represented by embodiments (or "avatars"), which also can vary from rich moving characters (such as in the Massive environment [1] or in Microcosm [2]) or simple 2D static cartoon images (as in The Palace, [3]).The design, development and use of CVEs is a growing research area with much potential for inter-disciplinary collaboration between researchers in the fields of computer science, psychology, sociology, cultural amp; media studies, architecture amp; urban planning, Artificial Intelligence, human computer interaction and CSCW.The Second International Conference dedicated to the design, development and evaluation of such Collaborative Virtual Environments (CVE'98) recently took place in Manchester. CVE'98 was part of Manchester's Digital Summer, celebrating the 50th Anniversary of the "birth of the Baby"; the demonstration of the first stored computer program. The conference took place over two days, from the 17th until the 19th June in the MANDEC Centre on the University of Manchester campus, and attracted 95 attendees from all over the world, drawn from computer science, human factors, sociology, psychology, graphic arts and other disciplines.
Reversible Long-Term Integration with Variable Stepsizes
Authors: Ernst Hairer, Daniel Stoffer
Venue: SIAM Journal on Scientific Computing (1997)

The numerical integration of reversible dynamical systems is considered. A backward analysis for variable stepsize one-step methods is developed, and it is shown that the numerical solution of a symmetric one-step method, implemented with a reversible stepsize strategy, is formally equal to the exact solution of a perturbed differential equation, which again is reversible. This explains geometrical properties of the numerical flow, such as the nearby preservation of invariants. In a second part, the efficiency of symmetric implicit Runge--Kutta methods (linear error growth when applied to integrable systems) is compared with explicit nonsymmetric integrators (quadratic error growth).
Analysis of techniques in the assessment of ultra-reliable computerized systems
Authors: Angelo Morzenti, Fabio A. Schreiber
Venue: ACM SIGSOFT Software Engineering Notes (1997)

A wide gap exists between the dependability figures, required by standardization committees for life-critical computer applications, and the current state-of-art in techniques to provide and assess them. In this paper we make a quick review of the best suited methodologies for each phase of the system life-cycle. We argue that the traditional view, which distinguishes between the behaviour of hardware and software components, should be clarified by separating the logical activities in the specification and in the design phases, which can be related both to hardware and to software, and the physical defects and operation stress, which only affect hardware.
Data distribution support on distributed shared memory multiprocessors
Authors: Rohit Chandra, Ding-Kai Chen, Robert Cox, Dror E. Maydan, Nenad Nedeljkovic, Jennifer M. Anderson
Venue: Proceedings of the ACM SIGPLAN 1997 conference on Programming language design and implementation (1997)

Cache-coherent multiprocessors with distributed shared memory are becoming increasingly popular for parallel computing. However, obtaining high performance on these machines mquires that an application execute with good data locality. In addition to making efiective use of caches, it is often necessary to distribute data structures across the local memories of the processing nodes, thereby reducing the latency of cache misses.We have designed a set of abstractions for performing data distribution in the context of explicitly parallel programs and implemented them within the SGI MIPSpro compiler system. Our system incorporates many unique features to enhance both programmability and performance. We address the former by providing a very simple programmming model with extensive support for error detection. Regarding performance, we carefully design the user abstractions with the underlying compiler optimizations in mind, we incorporate several optimization techniques to generate efficient code for accessing distributed data, and we provide a tight integration of these techniques with other optimizations within the compiler Our initial experience suggests that the directives are easy to use and can yield substantial performance gains, in some cases by as much as a factor of 3 over the same codes without distribution.
Flexible representation analysis
Authors: Zhong Shao
Venue: ACM SIGPLAN Notices (1997)

Statically typed languages with Hindley-Milner polymorphism have long been compiled using inefficient and fully boxed data representations. Recently, several new compilation methods have been proposed to support more efficient and unboxed multi-word representations. Unfortunately, none of these techniques is fully satisfactory. For example, Leroy's coercion-based approach does not handle recursive data types and mutable types well. The type-passing approach (proposed by Harper and Morrisett) handles all data objects, but it involves extensive runtime type analysis and code manipulations.This paper presents a new flexible representation analysis technique that combines the best of both approaches. Our new scheme supports unboxed representations for recursive and mutable types, yet it only requires little runtime type analysis. In fact, we show that there is a continuum of possibilities between the coercion-based approach and the type-passing approach. By varying the amount of boxing and the type information passed at runtime, a compiler can freely explore any point in the continuum---choosing from a wide range of representation strategies based on practical concerns. Finally, our new scheme also easily extends to handle type abstractions across ML-like higher-order modules.
An array-based algorithm for simultaneous multidimensional aggregates
Authors: Yihong Zhao, Prasad M. Deshpande, Jeffrey F. Naughton
Venue: Proceedings of the 1997 ACM SIGMOD international conference on Management of data (1997)

Computing multiple related group-bys and aggregates is one of the core operations of On-Line Analytical Processing (OLAP) applications. Recently, Gray et al. [GBLP95] proposed the &ldquo;Cube&rdquo; operator, which computes group-by aggregations over all possible subsets of the specified dimensions. The rapid acceptance of the importance of this operator has led to a variant of the Cube being proposed for the SQL standard. Several efficient algorithms for Relational OLAP (ROLAP) have been developed to compute the Cube. However, to our knowledge there is nothing in the literature on how to compute the Cube for Multidimensional OLAP (MOLAP) systems, which store their data in sparse arrays rather than in tables. In this paper, we present a MOLAP algorithm to compute the Cube, and compare it to a leading ROLAP algorithm. The comparison between the two is interesting, since although they are computing the same function, one is value-based (the ROLAP algorithm) whereas the other is position-based (the MOLAP algorithm). Our tests show that, given appropriate compression techniques, the MOLAP algorithm is significantly faster than the ROLAP algorithm. In fact, the difference is so pronounced that this MOLAP algorithm may be useful for ROLAP systems as well as MOLAP systems, since in many cases, instead of cubing a table directly, it is faster to first convert the table to an array, cube the array, then convert the result back to a table.
Evaluation of lot release policies for semiconductor manufacturing systems
Authors: Raka Sandell, Krishna Srinivasan
Venue: Proceedings of the 28th conference on Winter simulation (1996)

This paper describes a simulation based approach to evaluate and benchmark various lot release strategies in semiconductor manufacturing systems. A full-factorial experiment, with 5 factors, has been designed and executed for this purpose. A variation of the Bonferroni inequality is used to compute confidence intervals for differences in system performance for different operating strategies. The results show that no lot release policy dominates across all scenarios.
Heterogeneous Domain Decomposition for Singularly Perturbed Elliptic Boundary Value Problems
Authors: Marc Garbey, Hans G. Kaper
Venue: SIAM Journal on Numerical Analysis (1997)

A heterogeneous domain-decomposition method is presented for the numerical solution of singularly perturbed elliptic boundary value problems. The method, which is parallelizable at various levels, uses several ideas of asymptotic analysis. The subdomains match the domains of validity of the local (inner and outer) asymptotic expansions, and cut-off functions are used to match solutions in neighboring subdomains. The positions of the interfaces, as well as the mesh widths, depend on the small parameter $\varepsilon$. On the subdomains, iterative solution techniques are used, which may vary from one subdomain to another. The global convergence rate depends on $\varepsilon$; it generally increases like some power of $(\log (\varepsilon ^{-1}))^{-1}$ as $\varepsilon \downarrow 0$. The method is illustrated on several two-dimensional singular perturbation problems.
A Parallelizable Eigensolver for Real Diagonalizable Matrices with Real Eigenvalues
Authors: Steven Huss-Lederman, Anna Tsao, Thomas Turnbull
Venue: SIAM Journal on Scientific Computing (1997)

In this paper, preliminary research results on a new algorithm for finding all the eigenvalues and eigenvectors of a real diagonalizable matrix with real eigenvalues are presented. The basic mathematical theory behind this approach is reviewed and is followed by a discussion of the numerical considerations of the actual implementation. The numerical algorithm has been tested on thousands of matrices on both a Cray-2 and an IBM RS/6000 Model 580 workstation. The results of these tests are presented. Finally, issues concerning the parallel implementation of the algorithm are discussed. The algorithm's heavy reliance on matrix--matrix multiplication, coupled with the divide and conquer nature of this algorithm, should yield a highly parallelizable algorithm.
Analog VLSI Design Constraints of Programmable CellularNeural Networks
Authors: Peter Kinget, Michiel Steyaert
Venue: Analog Integrated Circuits and Signal Processing (1998)

Analog parallel signal processing systems, like cellular neural networks (CNN&lsquo;s), intrinsically have a high potential for perception-like signal processing tasks. The robust design of analog VLSI requires a good understanding of the capabilities as well as the limitations of analog signal processing. Implementation-oriented theoretical methods are described to compute the effect of all types circuit non-idealities with random or systematic causes on the static and dynamical behavior of CNN&lsquo;s and to derive specifications for the cell circuit building blocks. The fundamental impact of transistor mismatch on the trade-off between the speed, accuracy and power performance of CNN chips is demonstrated. A design methodology taking into account the effect of transistor mismatch is proposed and experimental results of a CNN chip implementation designed with this method are discussed.
Distributed versus Centralized Storage and Control forParallel Branch and Bound: Mixed Integer Programming on the CM-5
Authors: Jonathan Eckstein
Venue: Computational Optimization and Applications (1997)

This paper describes parallel, non-shared-memory implementation of the classical general mixed integer branch and bound algorithm, with experiments on the CM-5 family of parallel processors. The main issue in such an implementation is whether task scheduling and certain data-storage functions should be handled by a single processor, or spread among multiple processors. The centralized approach risks creating processing bottlenecks, while the more decentralized implementations differ more from the fundamental serial algorithm. Extensive computational tests on standard MIPLIB problems compare centralized, clustered, and fully decentralized task scheduling methods, using a novel combination of random work scattering and rendezvous-based global load balancing, along with a distributed &ldquo;control by token&rdquo; technique. Further experiments compare centralized and distributed schemes for storing heuristic &ldquo;pseudo-cost&rdquo; branching data. The distributed storage method is based on continual asynchronous reduction along a tree of redundant storage sites. On average, decentralized task scheduling appears at least as effective as central control, but pseudo-cost storage should be kept as centralized as possible.