ppxscal/embedding_network huggingface dataset:
Implicitly Restarted Krylov Subspace Methods for Stable Partial Realizations
Authors: Imad M. Jaimoukha, Ebrahim M. Kasenally
Venue: SIAM Journal on Matrix Analysis and Applications (1997)

This paper considers an implicitly restarted Krylov subspace method that approximates a stable, linear transfer function $f(s)$ of order $n$ by one of order $m$, where $n\gg m$. It is well known that oblique projections onto a Krylov subspace may generate unstable partial realizations. To remedy this situation, the oblique projectors obtained via classical Krylov subspace methods are supplemented with further projectors which enable the formation of stable partial realizations directly from $f(s)$. A key feature of this process is that it may be incorporated into an implicit restart scheme. A second difficulty arises from the fact that Krylov subspace methods often generate partial realizations that contain nonessential modes. To this end, balanced truncation may be employed to discard the unwanted part of the reduced-order model. This paper proposes oblique projection methods for large-scale model reduction that simultaneously compute stable reduced-order models while discarding all nonessential modes. It is shown that both of these tasks may be effected by a single oblique projection process. Furthermore, the process is shown to naturally fit into an implicit restart framework. The theoretical properties of these methods are thoroughly investigated, and exact low-dimensional expressions for the $\L^{\infty}$-norm of the residual errors are derived. Finally, the behavior of the algorithm is illustrated on two large-scale examples.
Assessing Software Review Meetings: Results of a Comparative Analysis of Two Experimental Studies
Authors: Adam A. Porter, Philip M. Johnson
Venue: IEEE Transactions on Software Engineering (1997)

Software review is a fundamental tool for software quality assurance. Nevertheless, there are significant controversies as to the most efficient and effective review method. One of the most important questions currently being debated is the utility of meetings. Although almost all industrial review methods are centered around the inspection meeting, recent findings call their value into question. In prior research the authors of this paper separately and independently conducted controlled experimental studies to explore this issue. This paper presents new research to understand the broader implications of these two studies. To do this, we designed and carried out a process of "reconciliation" in which we established a common framework for the comparison of the two experimental studies, reanalyzed the experimental data with respect to this common framework, and compared the results. Through this process we found many striking similarities between the results of the two studies, strengthening their individual conclusions. It also revealed interesting differences between the two experiments, suggesting important avenues for future research.
MPCR: an efficient and flexible chains of recurrences server
Authors: Olaf Bachmann
Venue: ACM SIGSAM Bulletin (1997)

MPCR is a stand-alone, flexible, and efficient implementation of the Chains of Recurrences (CR) method. It can be used interactively, as a network-based server, or as a library. Using the CR method, MPCR evaluates closed-form expressions over regular grids with great efficiency --- often hundreds of times faster than comparable programs. MPCR also features an MP (Multi Protocol) interface for data exchange, conditional CR simplification, use of intermediate evaluation arrays and generation of C source code. Evaluation timings are given and compared with other programs, and the algorithms which result in the high efficiency of MPCR are discussed.
End-to-end Internet packet dynamics
Authors: Vern Paxson
Venue: ACM SIGCOMM Computer Communication Review (1997)

We discuss findings from a large-scale study of Internet packet dynamics conducted by tracing 20,000 TCP bulk transfers between 35 Internet sites. Because we traced each 100 Kbyte transfer at both the sender and the receiver, the measurements allow us to distinguish between the end-to-end behaviors due to the different directions of the Internet paths, which often exhibit asymmetries. We characterize the prevalence of unusual network events such as out-of-order delivery and packet corruption; discuss a robust receiver-based algorithm for estimating "bottleneck bandwidth" that addresses deficiencies discovered in techniques based on "packet pair"; investigate patterns of packet loss, finding that loss events are not well-modeled as independent and, furthermore, that the distribution of the duration of loss events exhibits infinite variance; and analyze variations in packet transit delays as indicators of congestion periods, finding that congestion periods also span a wide range of time scales.
Multiresolution Schemes for the Numerical Solution of 2-D Conservation Laws I
Authors: Barna L. Bihari, Ami Harten
Venue: SIAM Journal on Scientific Computing (1997)

A generalization of Harten's multiresolution algorithms to two-dimensional (2-D) hyperbolic conservation laws is presented. Given a Cartesian grid and a discretized function on it, the method computes the local-scale components of the function by recursive diadic coarsening of the grid. Since the function's regularity can be described in terms of its scale or multiresolution analysis, the numerical solution of conservation laws becomes more efficient by eliminating flux computations wherever the solution is smooth. Instead, in those locations, the divergence of the solution is interpolated from the next coarser grid level. First, the basic 2-D essentially nonoscillatory (ENO) scheme is presented, then the 2-D multiresolution analysis is developed, and finally the subsequent scheme is tested numerically. The computational results confirm that the efficiency of the numerical scheme can be considerably improved in two dimensions as well.
Toward formalizing a validation methodology using simulation coverage
Authors: Aarti Gupta, Sharad Malik, Pranav Ashar
Venue: Proceedings of the 34th annual Design Automation Conference (1997)

The biggest obstacle in the formal verification of large designs istheir very large state spaces, which cannot be handled even bytechniques such as implicit state space traversal. The only viablesolution in most cases is validation by functional simulation. Unfortunately, this has the drawbacksof high computationalrequirementsdue to the large number of test vectors needed, and the lack of adequate coverage measures to characterize the quality of a given testset. To overcome these limitations, there has been recent interest inhybrid techniques which combine the strengths of formal verification and simulation. Formal verification-based techniques are usedon a test model (usually much smaller than the design) to derive a setof functional test vectors, which are then used for design validationthrough simulation. The test set generated typically satisfies somecoverage measure on the test model. Recent research has proposedthe use of state or transition coverage. However, no effort has beenmade to relate these measures to the coverage of design errors. Furthermore, the derivation of the test model remains largely ad-hoc,with few formal guidelines.We demonstrate that under a given set of assumptions, transitiontours on test models can be used for complete validation of an implementation against a specification, for a large and important classof designs that includes many programmable/hardwired, general-purpose processors/DSPs. A by-product of this study is specificguidelines for deriving the test model, motivated by the requirement of providing complete coverage of all errors. We illustrate theapplication of our methodology on a pipelined implementation of the DLX processor.
Function objects, function templates, and passage by behavior in C++
Authors: Richard Rasala
Venue: ACM SIGCSE Bulletin (1997)

Passing functions and function objects to general purpose routines is a powerful abstraction mechanism that should be taught in freshman computer science. In C++, a "function" can be defined directly by the user or by a library or can be defined indirectly via operator() as a member function of a class. It is not obvious how to treat these "functions" in a uniform manner. We will show how function templates in C++ provide an elegant and teachable mechanism for passing entities with functional behavior as arguments to other functions.
Integrated Time-to-Digital Converters Based on Interpolation
Authors: Elvi Räisänen-Ruotsalainen, Timo Rahkonen, Juha Kostamovaara
Venue: Analog Integrated Circuits and Signal Processing (1998)

The main features of two time-to-digital converters based on interpolation are presented, together with some measurement results. The first converter is based on digital delay line interpolators and has been implemented in a 1.2 &micro;m CMOS process. It has a single-shot resolution of 1 ns (&sgr;-value) and a nonlinearity less than &plusmn;50 ps in the measurement range 5 to 500 ns. The power consumption of the circuit is 15 mW. The second time digitizer has analog interpolators based on time-to-voltage conversion and has been implemented in a 1.2 &micro;m BiCMOS process. It has a single-shot resolution of 50 ps and a nonlinearity less than 150 ps in the measurement range 1 to 300 ns. The power consumption of this circuit is 200 mW.
Provably Good Partitioning and Load Balancing Algorithms for Parallel Adaptive N-Body Simulation
Authors: Shang-Hua Teng
Venue: SIAM Journal on Scientific Computing (1998)

We present an efficient and provably good partitioning and load balancing algorithm for parallel adaptive N-body simulation. The main ingredient of our method is a novel geometric characterization of a class of communication graphs that can be used to support hierarchical N-body methods such as the fast multipole method (FMM) and the Barnes--Hut method (BH). We show that communication graphs of these methods have a good partition that can be found efficiently sequentially and in parallel. In particular, we show that an N-body communication graph (either for BH or for FMM) can be partitioned into two subgraphs with equal computation load by removing only $O(\sqrt{n\log n})$ and O(n2/3(log n)1/3) number of nodes, respectively, for two and three dimensions. These bounds on node-partition imply bounds on edge-partition of $O(\sqrt{n}(\log n)^{3/2})$ and O(n2/3(log n)4/3), respectively, for two and three dimensions. To the best of our knowledge, this is the first theoretical result on the quality of partitioning N-body communication graphs for nonuniformly distributed particles. Our results imply that parallel adaptive N-body simulation can be made as scalable as computation on regular grids and as efficient as parallel N-body simulation on uniformly distributed particles.
Verification of VHDL designs using VAL
Authors: Larry M. Augustin, Benoit A. Gennart, Youm Huh, David C. Luckham, Alec G. Stanculescu
Venue: Proceedings of the 25th ACM/IEEE Design Automation Conference (1988)

VAL (VHDL Annotation Language) uses a small number of new language constructs to annotate VHDL hardware descriptions. VAL annotations, added to the VHDL entity declaration in the form of formal comments, express intended behavior common to all architectural bodies of the entity. Annotations are expressed as parallel processes that accept streams of input signals and generate constraints on output streams. VAL views signals as streams of values ordered by time. Generalized timing expressions allow the designer to refer to relative points on a stream. No concept of preemptive delayed assignment or inertial delay are needed when referring to different relative points in time on a stream. The VAL abstract state model permits abstract data types to be used in specifying history dependent device behavior. Annotations placed inside a VHDL architectural body define detailed correspondences between the behavior specification and architecture. The result is a simple but expressive language extension of VHDL with possible applications to automatic checking of VHDL simulations, hierarchical design, and automatic verification of hardware designs in VHDL.
Perturbation Theory for Algebraic Riccati Equations
Authors: Ji-guang Sun
Venue: SIAM Journal on Matrix Analysis and Applications (1998)

New perturbation results for the two different algebraic Riccati equations (continuous time and discrete time) are derived in a uniform manner. The new results are illustrated by numerical examples.
Out-of-order vector architectures
Authors: Roger Espasa, Mateo Valero, James E. Smith
Venue: Proceedings of the 30th annual ACM/IEEE international symposium on Microarchitecture (1997)

Register renaming and out-of-order instruction issue are now commonly used in superscalar processors. These techniques can also be used to significant advantage in vector processors, as this paper shows. Performance is improved and available memory bandwidth is used more effectively. Using a trace driven simulation we compare a conventional vector implementation, based on the Convex C3400, with an out-of-order, register renaming, vector implementation. When the number of physical registers is above 12, out-of-order execution coupled with register renaming provides a speedup of 1.24--1.72 for realistic memory latencies. Out-of-order techniques also tolerate main memory latencies of 100 cycles with a performance degradation less than 6%. The mechanisms used for register renaming and out-of-order issue can be used to support precise interrupts -- generally a difficult problem in vector machines. When precise interrupts are implemented, there is typically less than a 10% degradation in performance. A new technique based on register renaming is targeted at dynamically eliminating spill code; this technique is shown to provide an extra speedup ranging between 1.10 and 1.20 while reducing total memory traffic by an average of 15--20%.
Cryptanalysis of a Diophantine Equation Oriented Public Key Cryptosystem
Authors: C. S. Laih, M. J. Gau
Venue: IEEE Transactions on Computers (1997)

Lin et al. proposed a new public-key cipher system whose security is based upon the Diophantine equations. In this note, we show that their scheme is insecure under the ciphertext only attack.
A hierarchy-driven FPGA partitioning method
Authors: Helena Krupnova, Ali Abbara, Gabrièle Saucier
Venue: Proceedings of the 34th annual Design Automation Conference (1997)

This paper addresses an automatic partitioning method of adesign into several FPGAs. Although the circuit partitioningmethods have recently been significantly advanced, partitioningis commonly performed at the gate netlist level. To cope withlarge designs and explore the solution space efficiently,clustering of the logic is mandatory. In this paper, the hierarchyof the design, naturally introduced by the designer, guides thepartitioning. The basic concepts are introduced in terms of"envelope" delimiting hierarchy blocks. These concepts lead toan "envelope"-based clustering and to the proposed finalhierarchy-driven partitioning. Results are given on industrialexamples on XILINX 4000 technology.
ML and beyond
Authors: Robert Harper, John C. Mitchell
Venue: ACM SIGPLAN Notices (1997)

ML is a successful programming language that reconciles theoretical principles with pragmatic requirements. However, there are many shortcomings of the current language and implementations. This short note outlines some promising directions for future work.
Neural network method to determine the vigilance levels of the central nervous system, related to occupational chronic chemical stress
Authors: V. Tuulik, A. Raja, A. Meister, E. Lossmann
Venue: Technology and Health Care (1997)

The effects of chronic toxic occupational factors and functional disorders of the central nervous system (CNS) in chemical industry were studied. These factors cause various stages of chronic chemical stress on the human CNS together with changes of the vigilance levels. On the basis of QEEG data analysis and psychometric tests we identified three stages of occupational chemical stress syndromes according to the CNS vigilance level (ordered from light to severe): hypersthenic syndrome, hyposthenic syndrome, and organic psychosyndrome. Each syndrome is characterized by specific changes in the QEEG data. A perceptron-based neural network was developed for the classification of the QEEG data to one of the above-mentioned syndrome classes. The data of 77 patients and 10 healthy subjects were selected to test the algorithm. Different combinations of the QEEG data as input features to the classifier were chosen. The most reliable classification was obtained when QEEG data measured during the visual stimulation of the CNS were used. However, sometimes the algorithm was unable to solve the classification problem, or it took a very long time to train the perceptron. In part, difficulties arose from using a perceptron-based algorithm, which can classify only linearly separable data.
A Shooting Method for Fully Implicit Index-2 Differential Algebraic Equations
Authors: René Lamour
Venue: SIAM Journal on Scientific Computing (1997)

A shooting method for two-point boundary value problems (BVPs) for fully implicit index-1 and index-2 differential algebraic equations (DAEs) is presented. A combination of the shooting equations with a method of the calculation of consistent initial values leads to a system of nonlinear algebraic equations with a nonsingular Jacobian matrix. Examples are given.
Partial Classification: The Benefit of Deferred Decision
Authors: Yoram Baram
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1998)

It is shown that partial classification, which allows for indecision in certain regions of the data space, can increase a benefit function, defined as the difference between the probabilities of correct and incorrect decisions, joint with the event that a decision is made. This is particularly true for small data samples, which may cause a large deviation of the estimated separation surface from the intersection surface between the corresponding probability density functions. Employing a particular density estimation method, an indecision domain is naturally defined by a single parameter, whose optimal size, maximizing the benefit function, is derived from the data. The benefit function is shown to translate into profit in stock trading. Employing medical and economic data, it is shown that partial classification produces, on average, higher benefit values than full classification, assigning each new object to a class, and that the marginal benefit of partial classification reduces as the data size increases.
CSCL report: human computer interaction and educational tools (HCI-ET) conference report: May 18&ndash;27, 1997 Sozopol, Bulgaria
Authors: Margaret M. McManus
Venue: ACM SIGGROUP Bulletin (1997)

HCI-ET, a working conference of the IFIP WG 3.3, addressed the technologies and issues of Human Computer Interaction (HCI) regarding educational tools. The managerial and procedural operations of the conference were handled electronically through e-mail and the World Wide Web, two of the most common technologies of groupware. The conference Web site bttp://www-it.fmi.uni-sofia.bg/HCIET/describes the goals of the conference as well as abstracts of the papers, and serves as the primary resource for the material in this report.This report focuses on the topics which concern Computer-Supported Collaborative Learning (CSCL), especially Web-based education and training, and computer-supported collaborative skills. Additional articles on other issues in HCI were presented. The full articles will be published in book format.
GeoMiner: a system prototype for spatial data mining
Authors: Jaiwei Han, Krzysztof Koperski, Nebojsa Stefanovic
Venue: Proceedings of the 1997 ACM SIGMOD international conference on Management of data (1997)

Spatial data mining is to mine high-level spatial information and knowledge from large spatial databases. A spatial data mining system prototype, GeoMiner, has been designed and developed based on our years of experience in the research and development of relational data mining system, DBMiner, and our research into spatial data mining. The data mining power of GeoMiner includes mining three kinds of rules: characteristic rules, comparison rules, and association rules, in geo-spatial databases, with a planned extension to include mining classification rules and clustering rules. The SAND (Spatial And Nonspatial Data) architecture is applied in the modeling of spatial databases, whereas GeoMiner includes the spatial data cube construction module, spatial on-line analytical processing (OLAP) module, and spatial data mining modules. A spatial data mining language, GMQL (Geo-Mining Query Language), is designed and implemented as an extension to Spatial SQL [3], for spatial data mining. Moreover, an interactive, user-friendly data mining interface is constructed and tools are implemented for visualization of discovered spatial knowledge.
Simulation for intra- and inter-organisational business process modelling
Authors: George M. Giaglis, Ray J. Paul, Georgios I. Doukidis
Venue: Proceedings of the 28th conference on Winter simulation (1996)

Business process modelling (BPM) is an increasingly emerging field of simulation application. Although it has been practically demonstrated that simulation can be an effective tool for business redesign, there does not exist a comprehensive framework to explain the characteristics of business processes and identify specific requirements for their modelling. Furthermore, hardly any attention has been paid to the modelling of inter-organisational business systems. In this paper, we examine the nature of business processes in the light of modern change management approaches and propose a set of requirements for their modelling. We then concentrate on inter-organisational processes and argue that modelling problems can be much more difficult to overcome when more than one business is involved, mainly due to the multiplicity of decision making levels involved and the subsequent need for multi-level output analysis. Based on an empirical study, we illustrate the practical problems of modelling inter-organisational business systems and suggest desirable characteristics of simulation packages for that purpose.
In Defense of the Eight-Point Algorithm
Authors: Richard I. Hartley
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1997)

The fundamental matrix is a basic tool in the analysis of scenes taken with two uncalibrated cameras, and the eight-point algorithm is a frequently cited method for computing the fundamental matrix from a set of eight or more point matches. It has the advantage of simplicity of implementation. The prevailing view is, however, that it is extremely susceptible to noise and hence virtually useless for most purposes. This paper challenges that view, by showing that by preceding the algorithm with a very simple normalization (translation and scaling) of the coordinates of the matched points, results are obtained comparable with the best iterative algorithms. This improved performance is justified by theory and verified by extensive experiments on real images.