ppxscal/embedding_network huggingface dataset:
Fast, approximate synthesis of fractional Gaussian noise for generating self-similar network traffic
Authors: Vern Paxson
Venue: ACM SIGCOMM Computer Communication Review (1997)

Recent network traffic studies argue that network arrival processes are much more faithfully modeled using statistically self-similar processes instead of traditional Poisson processes [LTWW94, PF95]. One difficulty in dealing with self-similar models is how to efficiently synthesize traces (sample paths) corresponding to self-similar traffic. We present a fast Fourier transform method for synthesizing approximate self-similar sample paths for one type of self-similar process, Fractional Gaussian Noise, and assess its performance and validity. We find that the method is as fast or faster than existing methods and appears to generate close approximations to true self-similar sample paths. We also discuss issues in using such synthesized sample paths for simulating network traffic, and how an approximation used by our method can dramatically speed up evaluation of Whittle's estimator for H, the Hurst parameter giving the strength of long-range dependence present in a self-similar time series.
Magnetic resonance imaging and the reduction of motion artifacts: review of the principles
Authors: R. Van de Walle, I. Lemahieu, E. Achten
Venue: Technology and Health Care (1997)

Magnetic resonance (MR) imaging is a non-invasive diagnostic tool which is widely used nowadays. In this paper, the basic principles of MR imaging are explained and it is shown how images can be reconstructed in case of standard 2D Fourier Transform (2DFT) imaging. Several aspects of MR signal encoding are described. Unfortunately, motion of the patient during a magnetic resonance experiment often causes severe artifacts in the images. For example, in 2DFT imaging blurring and ghosting are seen and the appearance of motion artifacts remains one of the major drawbacks in MR imaging. Several methods to reduce motion artifacts in MR imaging have been proposed in the past. An overview of the principles on which these methods are based is given in this paper. Both post-processing methods and techniques that rely on gating or the use of alternative acquisition schemes such as projection reconstruction are discussed.
Embedded program timing analysis based on path clustering and architecture classification
Authors: R. Ernst, W. Ye
Venue: Proceedings of the 1997 IEEE/ACM international conference on Computer-aided design (1997)

Formal Program running time verification is an important issue in system design required for performance optimization under "first-time-right" design constraints and for real-time system verification. Simulation based approaches or simple instruction counting are not appropriate and risky for more complex architectures in particular with data dependent execution paths. Formal analysis techniques have suffered from loose timing bounds leading to significant performance penalties when strictly adhered to. We present an approach which combines simulation and formal techniques in a safe way to improve analysis precision and tighten the timing bounds. Using a set of processor parameters, it is adaptable to arbitrary processor architectures. The results show an unprecedented analysis precision allowing to reduce performance overhead for provably correct system or interface timing.
DECOMPOSER: a synthesizer for systolic systems
Authors: Pao-Po Hou, Robert Michael Owens, Mary Jane Irwin
Venue: Proceedings of the 25th ACM/IEEE Design Automation Conference (1988)

A tool for synthesizing systolic systems is introduced. Given a hierarchical specification of the computations to be performed and hints as to how these computations are to be performed, this tool generates an analysis of the hardware required to do the computations. The computations are specified as directed acyclic graphs and the hints tell the temporal and topological relationships of each computation. The systolic system is synthesized by traversing the graph and marking each computation with a processor name and a time stamp. This tool, called DECOMPOSER, is the newest entry in a tool set currently under development at Penn State [IO1]. Its output can subsequently be fed to the remaining tools in the tool set to generate a VLSI fabrication description of the systolic system.
Software development environment based on HyperNet
Authors: Nenad Marovac
Venue: ACM SIGSOFT Software Engineering Notes (1997)

In supporting groups working on development of large software programs we identify three classes of tools:1. CASE tools: tools which are used directly in the program development (specification, design, implementation, and testing).2. environment tools: tools which together are and effect the development environment, i.e. tools used in organizing and maintaining development information (program specifications, designs, code, test cases, etc.) which may be distributed world-wide.3. groupware tools: tools which are used to effect group communication and interaction, i.e. tools used for submission, organization and distribution of ideas and any issues related to the development and management process.In this paper we will address the second class of tools, the environment tools, and present an environment largely based on HyperNet - A tool to choreograph world wide distributed hypermedia documents. The environment incorporates three main functionalities:1. A project knowledge base and associated processor. The knowledge base stores all material relevant to a project, i.e. specification, design, implementation, testing and maintenance related documents and source code for the project including operating system scripts required to compile, link, execute and test the software.2. mechanism supporting libraries of reusable material. The material includes program specifications, design documents, code and test data and procedures.3. documentation processor which produces on-demand documentation for the project on any desirable level of detail.
An optimal bandwidth allocation strategy for the delivery of compressed prerecorded video
Authors: Wu-chi Feng, Farnam Jahanian, Stuart Sechrest
Venue: Multimedia Systems (1997)

The transportation of prerecorded, compressed video data without loss of picture quality requires the network and video servers to support large fluctuations in bandwidth requirements. Fully utilizing a client-side buffer for smoothing bandwidth requirements can limit the fluctuations in bandwidth required from the underlying network and the video-on-demand servers. This paper shows that, for a fixed-size buffer constraint, the critical bandwidth allocation technique results in plans for continuous playback of stored video that have (1) the minimum number of bandwidth increases, (2) the smallest peak bandwidth requirements, and (3) the largest minimum bandwidth requirements. In addition, this paper introduces an <i>optimal bandwidth allocation</i> algorithm which, in addition to the three critical bandwidth allocation properties, minimizes the total number of bandwidth changes necessary for continuous playback. A comparison between the optimal bandwidth allocation algorithm and other critical bandwidth-based algorithms using 17 full-length movie videos and 3 seminar videos is also presented.
On the limit of maximal density of sequences with a PerfectLinear Complexity Profile
Authors: Alice E. D. Houston
Venue: Designs, Codes and Cryptography (1997)

A binary sequence with a Perfect Linear Complexity Profile (PLCP) has all the jumps in its linear complexity profile of height exactly 1. We prove the conjecture made in Ho that the limit of the maximum density (proportion of ones) over all PLCPs of a particular length is 2/3 as the length tends to infinity.
S3: similarity search in CAD database systems
Authors: Stefan Berchtold, Hans-Peter Kriegel
Venue: Proceedings of the 1997 ACM SIGMOD international conference on Management of data (1997)

S3 is the prototype of a database system supporting the management and similarity retrieval of industrial CAD parts. The major goal of the system is to reduce the cost for developing and producing new parts by maximizing the reuse of existing parts. S3 supports the following three types of similarity queries: query by example (of an existing part in the database), query by sketch and thematic similarity query. S3 is an object-oriented system offering an adequate graphical user interface. On top of providing various state-of-the-art algorithms and index structures for geometry-based similarity retrieval, it is an excellent testbed for developing and testing new similarity algorithms and index structures.
Random variate generation for multivariate unimodal densities
Authors: Luc Devroye
Venue: ACM Transactions on Modeling and Computer Simulation (TOMACS) (1997)

A probability density on a finite-dimensional Euclidean space is orthounimodal with a given mode if within each orthant (quadrant) defined by the mode, the density is a monotone function of each of its arguments individually. Up to a linear transformation, most of the commonly used random vectors possess orthounimodal densities. To generate a random vector from a given orthounimodal density, several general-purpose algorithms are presented; and an experimental performance evaluation illustrates the potential efficiency increases that can be achieved by these algorithms versus naive rejection.
Sign of Gaussian Curvature From Curve Orientation in Photometric Space
Authors: Elli Angelopoulou, Lawrence B. Wolff
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1998)

We compute the sign of Gaussian curvature using a purely geometric definition. Consider a point p on a smooth surface S and a closed curve ¿ on S which encloses p. The image of ¿ on the unit normal Gaussian sphere is a new curve β. The Gaussian curvature at p is defined as the ratio of the area enclosed by ¿ over the area enclosed by β as ¿ contracts to p. The sign of Gaussian curvature at p is determined by the relative orientations of the closed curves ¿ and β.We directly compute the relative orientation of two such curves from intensity data. We employ three unknown illumination conditions to create a photometric scatter plot. This plot is in one-to-one correspondence with the subset of the unit Gaussian sphere containing the mutually illuminated surface normals. This permits direct computation of the sign of Gaussian curvature without the recovery of surface normals. Our method is albedo invariant. We assume diffuse reflectance, but the nature of the diffuse reflectance can be general and unknown. Error analysis on simulated images shows the accuracy of our technique. We also demonstrate the performance of this methodology on empirical data.
Reverse interpretation + mutation analysis = automatic retargeting
Authors: Christian S. Collberg
Venue: Proceedings of the ACM SIGPLAN 1997 conference on Programming language design and implementation (1997)

There are three popular methods for constructing highly retargetable compilers: (1) the compiler emits abstract machine code which is interpreted at run-time, (2) the compiler emits C code which is subsequently compiled to machine code by the native C compiler, or (3) the compiler's code-generator is generated by a back-end generator from a formal machine description produced by the compiler writer.These methods incur high costs at run-time, compile-time, or compiler-construction time, respectively.In this paper we will describe a novel method which promises to significantly reduce the effort required to retarget a compiler to a new architecture, while at the same time producing fast and effective compilers. The basic idea is to use the native C compiler at compiler construction time to discover architectural features of the new architecture. From this information a formal machine description is produced. Given this machine description, a native code-generator can be generated by a back-end generator such as BEG or burg.A prototype Automatic Architecture Discovery Unit has been implemented. The current version is general enough to produce machine descriptions for the integer instruction sets of common RISC and CISC architectures such as the Sun SPARC, Digital Alpha, MIPS, DEC VAX, and Intel x86. The tool is completely automatic and requires minimal input from the user: principally, the user needs to provide the internet address of the target machine and the command-lines by which the C compiler, assembler, and linker are invoked.
CSCW research in Germany
Authors: Rainer Unland
Venue: ACM SIGGROUP Bulletin (1998)

This article presents the main goals and intentions of some of the recently started research projects within the German CSCW-community1. It does not intend to present established results of (more or less) finished projects. All members of the German special interest group "CSCW in Organizations" were asked to submit a short description of their most recent research work. Since most projects are still in their early stage commonly available literature may not exist so far for some projects.The main intentions of this article are on the one hand to give an impression of the current state-of-the-art and interests of German CSCW research groups and on the other hand to stimulate international discussions and cooperations between researchers. Most of the presented projects are still in their starting phase. Therefore, I am pretty sure that the researchers whose work is described in this article are happy about every fruitful comment or constructive critics or any offer for cooperation if other researchers think that the presented work does nicely fit into or extend their work.For further information please contact the respective author directly or visit the appropriate WWW pages. An introduction the special interest group can be found here: http://www.informatik.uniessen.de/Fachgebiete/DatWiss/FG551/Introduction
Topologies for the parallel backtracking Prolog engine
Authors: L. Campanale, M. De Blasi, A. Gentile, F. Greco
Venue: Proceedings of the 23rd annual workshop and symposium on Microprogramming and microarchitecture (1990)

Some multicomputer networks for the implementation of the PBPE, a Parallel Backtracking Prolog Engine designed at the University of Bari, Italy, are considered. Two main subsystems, one for the management of clauses and another for interpretation of Prolog, each having its own topology, have to be connected together. An evaluation of different interconnection structures, aiming at using one single type of building block, is drawn taking into account the particular communication requirements of the PBPE. An experimental application using a variable number of transputers, linked in some of the topologies examined, is being developed.
Hybrid high-level nets
Authors: Ralf Wieting
Venue: Proceedings of the 28th conference on Winter simulation (1996)

This paper presents a new methodology for modeling and simulation of hybrid systems which is called Hybrid High-level Nets (HYNETS). The new methodology integrates three established modeling approaches into one language. High-level Petri Nets represent the basic discrete framework, differential algebraic equations (DAEs) are used to describe continuous systems behavior and object-oriented concepts improve the expressiveness and compactness of models. The paper explains basic ideas of the language and illustrates its usefulness with a small example.
PLAN: a packet language for active networks
Authors: Michael Hicks, Pankaj Kakkar, Jonathan T. Moore, Carl A. Gunter, Scott Nettles
Venue: Proceedings of the third ACM SIGPLAN international conference on Functional programming (1998)

PLAN (Packet Language for Active Networks) is a new language for programs that form the packets of a programmable network. These programs replace the packet headers (which can be viewed as very rudimentary programs) used in current networks. As such, PLAN programs are lightweight and of restricted functionality. These limitations are mitigated by allowing PLAN code to call node-resident service routines written in other, more powerful languages. This two-level architecture, in which PLAN serves as a scripting or 'glue' language for more general services, is the primary contribution of this paper. We have successfully applied the PLAN programming environment to implement an IP-free internetwork.PLAN is based on the simply typed lambda calculus and provides a restricted set of primitives and datatypes. PLAN defines a special construct called a chunk used to describe the remote execution of PLAN programs on other nodes. Primitive operations on chunks are used to provide basic data transport in the network and to support layering of protocols. Remote execution can make debugging difficult, so PLAN provides strong static guarantees to the programmer, such as type safety. A more novel property aimed at protecting network availability is a guarantee that PLAN programs use a bounded amount of network resources.
$\tau$-Extrapolation---Theoretical Foundation, Numerical Experiment, and Application to Navier--Stokes Equations
Authors: Klaus Bernert
Venue: SIAM Journal on Scientific Computing (1997)

This article deals with $\tau$-extrapolation---a modification of the multigrid method which leads to solutions with an improved convergence order. The number of numerical operations depends linearly on the problem size and is not much higher than for a multigrid method without this modification.Sections 1 and 2 contain a short description of the multigrid framework and a mathematical foundation of the $\tau$-extrapolation. Section 3 deals with a careful tuning of the multigrid components necessary for a successful application of $\tau$-extrapolation.Section 4 presents numerical illustrations to the theoretical investigations for one-dimensional linear and nonlinear test problems. Section 5 presents some experience with the use of $\tau$-extrapolation for the Navier--Stokes equations. In all cases the $\tau$-extrapolation leads to an improved convergence order.
The CSCW column: the quadrant model of GroupWare
Authors: Simon Kaplan
Venue: ACM SIGGROUP Bulletin (1997)

The CSCW column focuses on different aspects of computer-supported cooperative work (CSCW). In the last column I wrote about CSCW in general. In this column I am going to discuss the 'quadrant' groupware model.
Performance Analysis of Buffering Schemes in Wormhole Routers
Authors: Younes M. Boura, Chita R. Das
Venue: IEEE Transactions on Computers (1997)

Wormhole switched input-buffered and middle-buffered routers with virtual channels are analyzed in this paper. Middle buffering refers to the placement of virtual channels between the demultiplexors and multiplexors of a crossbar switch. An analytical model for multistage interconnection networks using middle-buffered switches is developed. In addition, extensive simulation is conducted to assess the performance of the two buffering techniques in different network topologies. The study demonstrates that middle buffering with virtual channels provides better performance than input buffering with virtual channels in multistage interconnection networks, two-dimensional meshes, and hypercubes.
Techniques for LAN Performance Analysis in a Real-TimeEnvironment
Authors: Philip M. Irey,  IV, Robert D. Harrison, David T. Marlow
Venue: Real-Time Systems (1998)

The Navy is a large user of real-time systems. A modern surface ship is deployed with hundreds of computers which are required for the ship to perform its mission. The Navy is moving away from using &rsquo;&rsquo;niche&lsquo;&lsquo; market components to meet its real-time computing needs and towards distributed processing using Commercial-Off-The-Shelf (COTS) computing components. The use of commercial real-time computing components requires careful evaluation to determine if they can meet the real-time requirements. This paper focuses on evaluating the communication resources for use aboard a Navy ship. Presented are: (1) Key performance metrics for assessing the communication capabilities of computers for use aboard Navy ships; (2) An assessment of existing methods for determining these metrics; (3) A methodology for collecting data to evaluate a particular component&lsquo;s performance related to these; (4) Examples of applying the methodology; and (5) Examples of quantitative analysis using the metrics.
Lazy Incremental Learning of Control Knowledge for EfficientlyObtaining Quality Plans
Authors: Daniel Borrajo, Manuela Veloso
Venue: Artificial Intelligence Review (1997)

General-purpose generative planners use domain-independent search heuristics to generate solutions for problems in a variety of domains. However, in some situations these heuristics force the planner to perform inefficiently or obtain solutions of poor quality. Learning from experience can help to identify the particular situations for which the domain-independent heuristics need to be overridden. Most of the past learning approaches are fully deductive and eagerly acquire correct control knowledge from a necessarily complete domain theory and a few examples to focus their scope. These learning strategies are hard to generalize in the case of nonlinear planning, where it is difficult to capture correct explanations of the interactions among goals, multiple planning operator choices, and situational data. In this article, we present a lazy learning method that combines a deductive and an inductive strategy to efficiently learn control knowledge incrementally with experience. We present hamlet, a system we developed that learns control knowledge to improve both search efficiency and the quality of the solutions generated by a nonlinear planner, namely prodigy4.0. We have identified three lazy aspects of our approach from which we believe hamlet greatly benefits: lazy explanation of successes, incremental refinement of acquired knowledge, and lazy learning to override only the default behavior of the problem solver. We show empirical results that support the effectiveness of this overall lazy learning approach, in terms of improving the efficiency of the problem solver and the quality of the solutions produced.
Selection of input models using bootstrap goodness-of-fit
Authors: Russell C. H. Cheng, Wayne Holland, Neil A. Hughes
Venue: Proceedings of the 28th conference on Winter simulation (1996)

Bootstrap methods are a natural adjunct of computer simulation experiments; both use resampling techniques to construct the statistical distributions of quantities of interest. In this paper we consider how bootstrap methods can be used in selecting appropriate input models for use in a computer simulation experiment. The proposed method uses a goodness of-fit statistic to decide on which of several competing input models should be used. We use bootstrapping to find the distribution of the test statistic under different assumptions as to which model is the correct fit. This allows the quality of fit of the different models to be compared. The bootstrapping process can be extended to the simulation experiment itself, allowing the effect of variability of estimated parameters on the simulation output to be assessed. The methodology is described and illustrated by application to a queueing example investigating the delays experienced by motorists caused by toll booths at a bridge river crossing.
Addendum: Is The Polar Decomposition Finitely Computable?
Authors: Alan George, Kh. Ikramov
Venue: SIAM Journal on Matrix Analysis and Applications (1997)

After the paper cited in the title [George and Ikramov, SIAM J. Matrix Anal. Appl., 17 (1996), pp. 348--354] was sent to the printer, the authors succeeded in finding a way to show that the answer to the title question is no. This brief note contains a proof of the result.
Ada, C, C++, and Java vs. the Steelman
Authors: David A. Wheeler
Venue: ACM SIGAda Ada Letters (1997)

This paper compares four computer programming languages (Ada95, C, C++, and Java) with the requirements of "Steelman", the original 1978 requirements document for the Ada computer programming language. This paper provides a view of the capabilities of each of these languages, and should help those trying to understand their technical similarities, differences, and capabilities.