ppxscal/embedding_network huggingface dataset:
Implications of hierarchical N-body methods for multiprocessor architectures
Authors: Jaswinder Pal Singh, John L. Hennessy, Anoop Gupta
Venue: ACM Transactions on Computer Systems (TOCS) (1995)

To design effective large-scale multiprocessors, designers need to understand the characteristics of the applications that will use the machines. Application characteristics of particular interest include the amount of communication relative to computation, the structure of the communication, and the local cache and memory requirements, as well as how these characteristics scale with larger problems and machines. One important class of applications is based on hierarchical N-body methods, which are used to solve a wide range of scientific and engineering problems efficiently. Important characteristics of these methods include the nonuniform and dynamically changing nature of the domains to which they are applied, and their use of long-range, irregular communication. This article examines the key architectural implications of representative applications that use the two dominant hierarchical N-body methods: the Barnes-Hut Method and the Fast Multipole Method.We first show that exploiting temporal locality on accesses to communicated data is critical to obtaining good performance on these applications and then argue that coherent caches on shared-address-space machines exploit this locality both automatically and very effectively. Next, we examine the implications of scaling the applications to run on larger machines. We use scaling methods that reflect the concerns of the application scientist and find that this leads to different conclusions about how communication traffic and local cache and memory usage scale than scaling based only on data set size. In particular, we show that under the most realistic form of scaling, both the communication-to-computation ratio as well as the working-set size (and hence the ideal cache size per processor) grow slowly as larger problems are run on larger machines. Finally, we examine the effects of using the two dominant abstractions for interprocessor communication: a shared address space and explicit message passing between private address spaces. We show that the lack of an efficiently supported shared address space will substantially increase the programming complexity and performance overheads for these applications.
Oblique Projection Methods for Large Scale Model Reduction
Authors: Imad M. Jaimoukha, Ebrahim M. Kasenally
Venue: SIAM Journal on Matrix Analysis and Applications (1995)

The aim of this paper is to consider approximating a linear transfer function $F(s)$ of McMillan degree $N$, by one of McMillan degree $m$ in which $N\gg m$ and where $N$ is large. Krylov subspace methods are employed to construct bases to parts of the controllability and observability subspaces associated with the state space realisation of $F(s)$. Low rank approximate grammians are computed via the solutions to low dimensional Lyapunov equations and computable expressions for the approximation errors incurred are derived. We show that the low rank approximate grammians are the exact grammians to a perturbed linear system in which the perturbation is restricted to the transition matrix, and furthermore, this perturbation has at most ${\rm rank}=2$. This paper demonstrates that this perturbed linear system is equivalent to a low dimensional linear system with state dimension no greater than $m$. Finally, exact low dimensional expressions for the ${\cal L}^{\infty}$ norm of the errors are derived. The model reduction of discrete time linear systems is considered via the use of the same Krylov schemes. Finally, the behaviour of these algorithms is illustrated on two large scale examples.
Supporting software reuse within an integrated software development environment (position paper)
Authors: Keith J. Ransom, Chris D. Marlin
Venue: ACM SIGSOFT Software Engineering Notes (1995)

Significant gains in programmer productivity have been achieved through the use of simple abstraction mechanisms that enhance the reuse of code. There are other useful forms of abstraction (over arbitrary identifier bindings, for example) which could further increase reuse rates, but are not well supported by programming languages; such forms may be better expressed by exploiting mechanisms provided by an integrated programming environment. This paper outlines ongoing work which aims to provide programming environment mechanisms that support the reuse of code via various forms of abstraction that complement those traditionally provided by programming languages. The concept of derivation-based reuse is also defined, and a generic framework for its support is outlined. In addition, a collection of environment mechanisms, intended to fit within this framework, are outlined.
Introducing data decomposition into VDM for tractable development of programs
Authors: Jian Lu
Venue: ACM SIGPLAN Notices (1995)

Formal program development by VDM comprises not only data reifications from abstract model to concrete model but also suitable operation decompositions. Usually, these two kinds of development steps are done independently with the order of "operation decompositions after data reifications". Furthermore, data reifications and operation decompositions are based on the whole model because no model split is allowed. If, however, larger specifications are aimed at, it is very important to provide support for model split and suitably interweave it with data reification and operation decomposition. In this paper, we introduce a new concept---data decomposition which is based on the ideas of model split, modularisation and operation decomposition, and combine it with VDM to form a more general formal development method DD-VDM. As a result, a more flexible development strategy can be adopted and the development complexity can be effectively controlled.
Computational Complexity of Two-Dimensional Regions
Authors: Arthur W. Chou, Ker-I Ko
Venue: SIAM Journal on Computing (1995)

The computational complexity of bounded sets of the two-dimensional plane is studied in the discrete computational model. We introduce four notions of polynomial-time computable sets in R$^2$ and study their relationship. The computational complexity of the winding number problem, membership problem, distance problem, and area problem is characterized by the relations between discrete complexity classes of the NP theory.
Evaluating the locality benefits of active messages
Authors: Ellen Spertus, William J. Dally
Venue: ACM SIGPLAN Notices (1995)

A major challenge in fine-grained computing is achieving locality without excessive scheduling overhead. We built two J-Machine implementations of a fine-grained programming model, the Berkeley Threaded Abstract Machine. One implementation takes an Active Messages approach, maintaining a scheduling hierarchy in software in order to improve data cache performance. Another approach relies on the J-Machine's message queues and fast task switch, lowering the control costs at the expense of data locality. Our analysis measures the costs and benefits of each approach, for a variety of programs and cache configurations. The Active Messages implementation is strongest when miss penalties are high and for the finest-grained programs. The hardware-buffered implementation is strongest in direct-mapped caches, where it achieves substantially better instruction cache performance.
Simulating an emergency department &ldquo;is as much fun as&hellip;&rdquo;
Authors: Anthony Kirtland, Jacqueline Lockwood, Karen Poisker, Linda Stamp, Patricia Wolfe
Venue: Proceedings of the 27th conference on Winter simulation (1995)

The purpose of the project is to improve the operation of Peninsula Regional Medical Center's (PRMC) Emergency Department (ED) and decrease patient dissatisfaction with length of stay. The goal is to reduce patient throughput times and determine the appropriate staffing levels. An additional goal is to aid in identifying other system changes to improve patient and department flows in the ED through the use of simulation.
Join queries with external text sources: execution and optimization techniques
Authors: Surajit Chaudhuri, Umeshwar Dayal, Tak W. Yan
Venue: Proceedings of the 1995 ACM SIGMOD international conference on Management of data (1995)

Text is a pervasive information type, and many applications require querying over text sources in addition to structured data. This paper studies the problem of query processing in a system that loosely integrates an extensible database system and a text retrieval system. We focus on a class of conjunctive queries that include joins between text and structured data, in addition to selections over these two types of data. We adapt techniques from distributed query processing and introduce a novel class of join methods based on probing that is especially useful for joins with text systems, and we present a cost model for the various alternative query processing methods. Experimental results confirm the utility of these methods. The space of query plans is extended due to the additional techniques, and we describe an optimization algorithm for searching this extended space. The techniques we describe in this paper are applicable to other types of external data managers loosely integrated with a database system.
Interworking between Digital European Cordless Telecommunications and a distributed packet switch
Authors: Sudarshan Rao, David J. Goodman, Gregory P. Pollini, Kathleen S. Meier-Hellstern
Venue: Wireless Networks (1995)

The Digital European Cordless Telecommunications (DECT) standard specifies an air interface. DECT requires an external infrastructure to transfer information between wireless terminals, and to transfer information between a wireless terminal and a fixed network. The Public Switched Telephone Network, the GSM Cellular Network, Private Branch Exchanges and mobile data networks are all under investigation as DECT backbone networks. In this paper we look to the future and describe interworking between the DECT air interface and a wireless network infrastructure referred to as a Cellular Packet Switch. To achieve distributed network control, the Cellular Packet Switch uses an IEEE 802.6 Metropolitan Area Network to link base stations, databases and fixed networks. In this paper we specify details of DECT information transport on the Metropolitan Area Network. We also give examples of Network Layer message flows for location updating and handover. The messages for other key procedures including call origination and release appear in a more detailed technical report.
Never mind the paradigm, what about multiparadigm languages?
Authors: Timothy A. Budd, Rajeev K. Pandey
Venue: ACM SIGCSE Bulletin (1995)

A source of great debate among educators is the choice of a programming language in the various computer science courses. In recent years the focus has shifted from features of various programming languages to arguments about the various paradigms that the languages embody. The approach suggested here is to expose students to all of the major paradigms, via the use of a multiparadigm language, as opposed to attempting to identify "the" correct paradigm. In this paper, we first describe the multiparadigm language Leda and its constituent paradigms. We then identify points in the curriculum at which to introduce a multiparadigm language, and some consequences of these choices.
Design of object-oriented simulations in C++
Authors: Jeffrey A. Joines, Stephen D. Roberts
Venue: Proceedings of the 27th conference on Winter simulation (1995)

A set of object classes have been written in C++ which can be used to create simulation models and simulation packages. The simulations built with these classes possess the benefits of an object-oriented design, including the use of inheritance, encapsulation, polymorphism, run-time binding, and parameterized typing. These concepts are illustrated by creating a network queuing simulation language which has several notable features not available in other similar languages. Object-oriented simulations provide full accessibility to the base language, faster executions, portable models and executables, a multi-vendor implementation language, and a growing variety of complementary development tools.
A measurement-based admission control algorithm for integrated services packet networks
Authors: Sugih Jamin, Peter B. Danzig, Scott Shenker, Lixia Zhang
Venue: Proceedings of the conference on Applications, technologies, architectures, and protocols for computer communication (1995)

Many designs for integrated service networks offer a bounded delay packet delivery service to support real-time applications. To provide bounded delay service, networks must use admission control to regulate their load. Previous work on admission control mainly focused on algorithms that compute the worst case theoretical queueing delay to guarantee an absolute delay bound for all packets. In this paper we describe a measurement-based admission control algorithm for predictive service, which allows occasional delay violations. We have tested our algorithm through simulations on a wide variety of network topologies and driven with various source models, including some that exhibit long-range dependence, both in themselves and in their aggregation. Our simulation results suggest that, at least for the scenarios studied here, the measurement-based approach combined with the relaxed service commitment of predictive service enables us to achieve a high level of network utilization while still reliably meeting the delay bound.
Computer language usage in CS1: survey results
Authors: Suzanne Pawlan Levy
Venue: ACM SIGCSE Bulletin (1995)

The Reid Report [Reid 94] is a list of more than 400 schools throughout the world and the language they are using in their first computer science course (commonly referred to as ACM's CS1). It is a voluntary report updated regularly. Its list of schools is not exhaustive or complete. Based on this report, 139 colleges and universities within the United States who are not using Pascal were surveyed. The intent of the survey was threefold: bull; to find out why these schools are using their choice of language in their CS1 course, bull; how the instructors at these schools feel about their current language as it compares to Pascal in the way it aids in the teaching of introductory programming skills, and bull; which language these instructors feel is the best one to use in a CS1 course.The results of this survey, conducted in February 1995, are summarized below.
Deneb/ERGO: a simulation based human factors tool
Authors: Narinder Nayar
Venue: Proceedings of the 27th conference on Winter simulation (1995)

The Deneb/ERGO software is an interactive, 3D simulation-based tool for human factors and ergonomic analysis. The tool is very useful for workplace design and analysis, allowing the user to rapidly prototype human motion within a work area using a graphical motion programming paradigm. Capabilities are provided for developing time standards and studying the ergonomics of a job related to lifting, energy expenditure and posture analysis using percentile based, fully articulated 3D human models. The presentation first focuses on the need for such a software tool and then discusses the various motion programming and analysis capabilities of the software.
Applying specialization to process models
Authors: George M. Wyner, Jintae Lee
Venue: Proceedings of conference on Organizational computing systems (1995)

Object-oriented analysis and design methodologies take full advantage of the object approach when it comes to modeling the objects in a system. However, system behavior continues to be modeled using essentially the same tools as in traditional systems analysis: state diagrams and dataflow diagrams. In this paper we extend the notion of specialization to these process representations and identify a set of transformations which, when applied to a process description, always result in specialization. We analyze specific examples in detail and demonstrate that such a use of specialization is not only theoretically possible, but shows promise as a method for categorizing and analyzing processes. We identify a number of apparent inconsistencies between process specialization and the object specialization which is part of the object-oriented approach. We demonstrate that these apparent inconsistencies are superficial and that the approach we take is compatible with the traditional notion of specialization.
An improved incomplete Cholesky factorization
Authors: Mark T. Jones, Paul E. Plassmann
Venue: ACM Transactions on Mathematical Software (TOMS) (1995)

Incomplete factorization has been shown to be a good preconditioner for the conjugate gradient method on a wide variety of problems. It is well known that allowing some fill-in during the incomplete factorization can significantly reduce the number of iterations needed for convergence. Allowing fill-in, however, increases the time for the factorization and for the triangular system solutions. Additionally, it is difficult to predict a priori how much fill-in to allow and how to allow it. The unpredictability of the required storage/work and the unknown benefits of the additional fill-in make such strategies impractical to use in many situations. In this article we motivate, and then present, two &ldquo;black-box&rdquo; strategies that significantly increase the effectiveness of incomplete Cholesky factorization as a preconditioner. These strategies require no parameters from the user and do not increase the cost of the triangular system solutions. Efficient implementations for these algorithms are described. These algorithms are shown to be successful for a variety of problems from the Harwell-Boeing sparse matrix collection.
An approach to natural gesture in virtual environments
Authors: Alan Wexelblat
Venue: ACM Transactions on Computer-Human Interaction (TOCHI) (1995)

This article presents research&mdash;an experiment and the resulting prototype&mdash;on a method for treating gestural input so that it can be used for multimodal applications, such as interacting with virtual environments. This method involves the capture and use of natural , empty-hand gestures that are made during conventional descriptive utterances. Users are allowed to gesture in a normal continuous manner, rather than being restricted to a small set of discrete gestural commands as in most other systems. The gestures are captured and analyzed into a higher-level description. This description can be used by an application-specific interpreter to understand the gestural input in its proper context. Having a gesture analyzer of this sort enables natural gesture input to any appropriate application.
Approximating the Minimum Equivalent Digraph
Authors: Samir Khuller, Balaji Raghavachari, Neal Young
Venue: SIAM Journal on Computing (1995)

The MEG (minimum equivalent graph) problem is the following: "Given a directed graph, find a smallest subset of the edges that maintains all reachability relations between nodes." This problem is NP-hard; this paper gives an approximation algorithm achieving a performance guarantee of about 1.64 in polynomial time. The algorithm achieves a performance guarantee of 1.75 in the time required for transitive closure. The heart of the MEG problem is the minimum SCSS (strongly connected spanning subgraph) problem --- the MEG problem restricted to strongly connected digraphs. For the minimum SCSS problem, the paper gives a practical, nearly linear-time implementation achieving a performance guarantee of 1.75. The algorithm and its analysis are based on the simple idea of contracting long cycles. The analysis applies directly to $2$-\Exchange, a general "local improvement" algorithm, showing that its performance guarantee is 1.75.
Performance evaluation of an automated material handling system for a machining line using simulation
Authors: Carlos B. Ramírez Cerda
Venue: Proceedings of the 27th conference on Winter simulation (1995)

In the evaluation of a material handling system, multiple factors should be considered, including the plant's facilities, the machinery, the material handling equipment, and of course, the people involved. Simulation techniques can be effectively used in all the phases of this process in order to understand the behavior of manufacturing systems, from the material handling concept definition throughout the system's final implementation In this paper, an automated material handling system for a cylinder block machining line is proposed and evaluated by means of discrete event simulation using the ProModel simulator. Initially, the machining line is modeled with manual material handling to get an estimate of the true line capacity. Then the proposed conveyor system is modeled, and the systems are compared by means of confidence intervals. The results revealed that the automated material handling system causes a slight decrease in the system throughput, while gaining the benefits of a Just in Time based system.
Battle command AAR methodology: a paradigm for effective training
Authors: John A. Hixson
Venue: Proceedings of the 27th conference on Winter simulation (1995)

An old Army adage claims, "If no assessment has been made, then no training has been conducted." While unit exercises through the battalion level can be effectively observed and assessed, it is difficult to assess exercises conducted at the division and corps levels using traditional means. The number and physical separation of the participating elements, including players, opposing forces and exercise control, constitute significant obstacles to comprehensive observation, correlation and assessment of exercise events and actions. The Battle Command Training Program's After Action Review (AAR) methodology, used in conjunction with simulations and supporting technology, provides an effective means for training assessment in large formations. This is accomplished through use of a simulation as an exercise driver, automation of AAR data collection, automation support for analysis and AAR product preparation, distributed AARs, and by linking widely separated players, supporting units and opposing forces over a wide area network (WAN).
Using role components in implement collaboration-based designs
Authors: Michael VanHilst, David Notkin
Venue: ACM SIGPLAN Notices (1996)

In this paper we present a method of code implementation that works in conjunction with collaboration and responsibility based analysis modeling techniques to achieve better code reuse and resilience to change. Our approach maintains a closer mapping from responsibilities in the analysis model to entities in the implementation. In so doing, it leverages the features of flexible design and design reuse found in collaboration-based design models to provide similar adaptability and reuse in the implementation. Our approach requires no special development tools and uses only standard features available in the C++ language. In an earlier paper we described the basic mechanisms used by our approach and discussed its advantages in comparison to the framework approach. In this paper we show how our approach combines code and design reuse, describing specific techniques that can be used in the development of larger applications.
All-to-All Personalized Communication in a Wormhole-Routed Torus
Authors: Yu-Chee Tseng, Sandeep K. S. Gupta
Venue: IEEE Transactions on Parallel and Distributed Systems (1996)

All-to-all personalized communication, or complete exchange, is at the heart of numerous applications in parallel computing. It is one of the most dense communication patterns. In this paper, we consider this problem in a torus of any dimension with the wormhole-routing capability. We propose complete exchange algorithms that use optimal numbers of phases (if each side of the tori is a multiple of eight) or asymptotically optimal numbers of phases (otherwise). Interestingly, in order to achieve this, we only make weak assumptions¿that a node is capable of sending and receiving at most one message at a time, and the network is capable of supporting the dimension-ordered (or e-cube) minimum routing.