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Articles 54211 - 54240 of 57999

Full-Text Articles in Physical Sciences and Mathematics

A Computer-Based Editor For Lerdahl And Jackendoff's Rhythmic Structures, Bruno Degazio Jan 1996

A Computer-Based Editor For Lerdahl And Jackendoff's Rhythmic Structures, Bruno Degazio

Publications and Scholarship

In “A Generative Theory of Tonal Music”, Lerdahl and Jackendoff discuss two forms of rhythmic structure which they call metrical structure and grouping structure. Together these constitute a basis for an analytical understanding of rhythmic structure in music. This article is about a software based editor which allows the interactive exploration of these two types of hierarchical rhythmic structures.

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Leap Forward Virtual Clock: An O(Loglogn) Fair Queuing Scheme With Guaranteed Delays And Throughput Fairness, Subhash Suri, George Varghese, Girish P. Chandranmenon Jan 1996

Leap Forward Virtual Clock: An O(Loglogn) Fair Queuing Scheme With Guaranteed Delays And Throughput Fairness, Subhash Suri, George Varghese, Girish P. Chandranmenon

All Computer Science and Engineering Research

We describe an efficient fair queuing scheme, Leap Forward Virtual Clock, that provides end-to-end delay bounds almost identical to that of PGPS fair queuing, along with throughput fairness. Our scheme can be implemented with a worst-case time O(loglogN) per packet guaranteed delay and throughput fairness. As its name suggests, our scheme is based on Zhang's virtual clock. While the original virtual clock scheme does not achieve throughput fairness, we can modify it with a simple leap forward mechanism that keeps the server clock from lagging too far behind the packet tags. We prove that our scheme guarantees a fair share …

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Vaudeville: A High Performance, Voice-Activated Teleconferencing Application, Jyoti K. Parwatikar, T. Paul Mccartney, John D. Dehart, Maynard Engebretson, Kenneth J. Goldman Jan 1996

Vaudeville: A High Performance, Voice-Activated Teleconferencing Application, Jyoti K. Parwatikar, T. Paul Mccartney, John D. Dehart, Maynard Engebretson, Kenneth J. Goldman

All Computer Science and Engineering Research

We present a voice-activated, hands-off, ATM-based video conferencing application. The application, called Vaudeville, features high quality NTSC video, voice-activated audio transmission, audio bridging of two audio streams, and voice-activated video switching. It supports multiple simultaneous multi-party conferences using a scalable multicast mechanism. We describe how Vaudeville was built using a component-based distributed programming environment. We also describe the algorithms used to contorl the audio and video of the applciation. Audio and video are encoded in hardware using an ATM hardware multimedia interface.

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Design And Implementation Of A Practical Security-Conscious Electronic Polling System, Lorrie Faith Cranor, Ron K. Cytron Jan 1996

Design And Implementation Of A Practical Security-Conscious Electronic Polling System, Lorrie Faith Cranor, Ron K. Cytron

All Computer Science and Engineering Research

We present the design and implementation of Sensus, a practical, secure and private system for conducting surveys and elections over computer networks. Expanding on the work of Fujioka, Okamoto, and Ohta, Sensus uses blind signatures to ensure that only registered voters can vote and that each registered voter only votes once, while at the same time maintaining voters' privacy. Sensus allows voters to verify independently that their votes were counted correctly, and anonymously challenge the results should their votes be miscounted. We outline seven desirable properties of voting systems and show that Sensus satisfied these properties well, in some cases …

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Bringing Real-Time Scheduling Theory And Practice Closer For Multimedia Computing, R. Gopalakrishnan, Guru M. Parulkar Jan 1996

Bringing Real-Time Scheduling Theory And Practice Closer For Multimedia Computing, R. Gopalakrishnan, Guru M. Parulkar

All Computer Science and Engineering Research

This paper seeks to bridge the gap between theory and practice of real-time scheduling in the domain of multimedia computer systems. We show that scheduling algorithms that are good in theory, often have practical limitations. However when these algorithms are modified based on practical considerations, existing theoretical results cannot be used as they are. In this paper we motivate the need for new scheduling schemes for multimedia protocol processing, and demonstrate their real-time performance in our prototype implementation. We then explain the observed results by analysis and measurement. More specifically, we show that using strict preemption can introduce overheads in …

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Distributed Stream Filtering For Database Applications, William M. Shapiro, Kenneth J. Goldman Jan 1996

Distributed Stream Filtering For Database Applications, William M. Shapiro, Kenneth J. Goldman

All Computer Science and Engineering Research

Distributed stream filtering is a mechanism for implementing a new class of real-time applications with distributed processing requirements. These applications require scalable architectures to support the efficient processing and multiplexing of large volumes of continuously generated data. This paper provides an overview of a stream-oriented model for database query processing and presents a supporting implementation. To facilitate distributed stream filtering, we introduce several new query processing operations, including pipelined filtering that efficiently joins and eliminates duplicates from database streams and a new join method, the progressive join, that joins streams of tuples. Finally, recognizing that the stream-oriented model results in …

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An Algorithm For Message Delivery To Mobile Units, Amy L. Murphy, Gruia-Catalin Roman, George Varghese Jan 1996

An Algorithm For Message Delivery To Mobile Units, Amy L. Murphy, Gruia-Catalin Roman, George Varghese

All Computer Science and Engineering Research

With recent advances in wireless communication and the ubiquity of laptops, mobile computing has become an important research area. An essential problem in mobile computing is the delivery of a message from a source to either a single mobile node, unicast, or to a group of mobile nodes, multicast. Standard solutions used in Mobile IP and cellular phones for the unicast problem rely on tracking the mobile unit. Tracking solutions scale badly when mobile nodes move frequently, and do not generalize well to multicast delivery. Our paper proposes a new message delivery algorithm for micromobility based on a modification of …

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Mobile Unity Coordination Constructs Applied To Packet Forwarding For Mobile Hosts, Peter J. Mccann, Gruia-Catalin Roman Jan 1996

Mobile Unity Coordination Constructs Applied To Packet Forwarding For Mobile Hosts, Peter J. Mccann, Gruia-Catalin Roman

All Computer Science and Engineering Research

With recent advances in wireless communication technology, mobile computing is an increasingly important area of research. A mobile system is one where independently executing components may migrate through some space during the course of the computation, and where the pattern of connectivity among the components changes as they move in and out of proximity. Mobile UNITY is a language and logic for specifying and reasoning about mobile systems, the components of which must operate in a highly decoupled way. In this paper it is argued that Mobile UNITY contributes to the modular development of system specifications because of the declarative …

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A Usability Study Of End-User Construction Of Direct Manipulation User Interfaces, T Paul Mccartney Jan 1996

A Usability Study Of End-User Construction Of Direct Manipulation User Interfaces, T Paul Mccartney

All Computer Science and Engineering Research

This paper describes an empirical study of end-users that tested the usability of The Programmers' Playground graphical environment. The Programmers' Playground is a software library and run-time system for constructing distributed multimedia applications. Playground's graphical environment enables end-users to create direct manipulation graphical user interfaces (GUIs) and to dynamically configure communication among distributed application components. In this study, 28 end-users with no prior experience in distributed computing or user interface construction were timed and evaluated on several tasks using our graphical environment. Tasks included the use of direct and indirect constraint relationships, visual configuration of distributed applications, and graphical user …

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A Formal Preparation For Object-Oriented Query Optimisation, Catherine Higgins Jan 1996

A Formal Preparation For Object-Oriented Query Optimisation, Catherine Higgins

Articles

This paper describes work that is in progress on a formalised preparation to object-oriented query optimisation. Such preparation is conducive to the development of optimisation strategies. As an example of a formal preparation, this paper presents a formalised object algebra, a suggested optimisation method and an implementation of an algebraic converter suitable for DAPLEX.

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Torus Routing In The Presence Of Multicasts, Hiroki Ishibashi Jan 1996

Torus Routing In The Presence Of Multicasts, Hiroki Ishibashi

Theses Digitization Project

No abstract provided.

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A Systematic Tradeoff Methodology For Acquiring And Validating Imprecise Requirements, J. Yen, Xiaoqing Frank Liu, W. A. Tiao Jan 1996

A Systematic Tradeoff Methodology For Acquiring And Validating Imprecise Requirements, J. Yen, Xiaoqing Frank Liu, W. A. Tiao

Computer Science Faculty Research & Creative Works

Requirement analysis is one of the most important phases in a software development process. Existing requirement methodologies are limited in specifying requirements that are usually vague and imprecise, and in supporting tradeoff analysis between the conflicting requirements. In this paper, the elasticity of imprecise requirements is captured using fuzzy logic to facilitate tradeoffs between conflicting requirements. Based on the marginal rate of substitution in decision science, we have developed a systematic approach to elicit the structures and the parameters of imprecise requirements, to validate the scheme for aggregating requirements, and to assess relative priorities of conflicting requirements.

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Frequency Coordination Between Adjacent Carriers Of Two Cdma Operators, Seung Jong Park, Hun Bum Ha, Jong Tai Chung, Yoon Sub Shim, Do Young Lee Jan 1996

Frequency Coordination Between Adjacent Carriers Of Two Cdma Operators, Seung Jong Park, Hun Bum Ha, Jong Tai Chung, Yoon Sub Shim, Do Young Lee

Computer Science Faculty Research & Creative Works

Frequency coordination is the process that assigns frequency bands to neighboring or coexisting systems to minimize interference. This interference is caused by unwanted signals from adjacent frequency bands. Especially, interference is maximized by the spatial near-far problem which occurs in case two different cellular systems serve. This critical case happens when different cellular operators using the adjacent carriers do not collocate their base stations (BS). In this paper, we investigate the frequency coordination when two CDMA operators using adjacent CDMA carriers don't collocate their BS. In order to lessen the unwanted interference, we put the guard band which separates adjacent …

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Automatic Pcb Inspection Algorithms: A Survey, Madhav Moganti, Fikret Ercal, Cihan H. Dagli, Shou Tsunekawa Jan 1996

Automatic Pcb Inspection Algorithms: A Survey, Madhav Moganti, Fikret Ercal, Cihan H. Dagli, Shou Tsunekawa

Computer Science Faculty Research & Creative Works

The importance of the inspection process has been magnified by the requirements of the modern manufacturing environment. In electronics mass-production manufacturing facilities, an attempt is often made to achieve 100% quality assurance of all parts, subassemblies, and finished goods. A variety of approaches for automated visual inspection of printed circuits have been reported over the past two decades. In this survey, algorithms and techniques for the automated inspection of printed circuit boards are examined. A classification tree for these algorithms is presented and the algorithms are grouped according to this classification. This survey concentrates mainly on image analysis and fault …

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Optimization Of The Discriminatory Power Of A Trigram Based Document Clustering Algorithm Using Evolutionary Computation, Daniel R. Tauritz Jan 1996

Optimization Of The Discriminatory Power Of A Trigram Based Document Clustering Algorithm Using Evolutionary Computation, Daniel R. Tauritz

Computer Science Faculty Research & Creative Works

No abstract provided.

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Semantic And Schematic Similarities Between Database Objects: A Context-Based Approach, Vipul Kashyap, Amit P. Sheth Jan 1996

Semantic And Schematic Similarities Between Database Objects: A Context-Based Approach, Vipul Kashyap, Amit P. Sheth

Kno.e.sis Publications

In a multidatabase system, schematic conflicts between two objects are usually of interest only when the objects have some semantic similarity. We use the concept of semantic proximity, which is essentially an abstraction/mapping between the domains of the two objects associated with the context of comparison. An explicit though partial context representation is proposed and the specificity relationship between contexts is defined. The contexts are organized as a meet semi-lattice and associated operations like the greatest lower bound are defined. The context of comparison and the type of abstractions used to relate the two objects form the basis of a …

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Syllogism Solving Under Time Pressure, Gondy Leroy, Koen Lamberts Jan 1996

Syllogism Solving Under Time Pressure, Gondy Leroy, Koen Lamberts

CGU Faculty Publications and Research

No abstract provided.

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Analysis Of Mpeg Compressed Video Traffic, Jerome R. Cox Jr., O. Matthew Beal Jan 1996

Analysis Of Mpeg Compressed Video Traffic, Jerome R. Cox Jr., O. Matthew Beal

All Computer Science and Engineering Research

This paper outlines a study of MPEG compressed video sequences and simulation of multiplexed video traffic in the ATM environment. A number of statistical characteristics including autocorrelation and variance of MPEG-1 compressed video sequences are used to characterize the 16 sample traces used in this study. From these measurements, a preliminary model is developed which utilizes basic measurements of the individual component video sequences to predict bandwidth requirements and cell loss of the multiplexed video traffic.

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Simulation Of Asynchronous Instruction Pipelines, Chia-Hsing Chien, Mark A. Franklin Jan 1996

Simulation Of Asynchronous Instruction Pipelines, Chia-Hsing Chien, Mark A. Franklin

All Computer Science and Engineering Research

This paper presents the ARAS simulator with which asynchronous instruction pipelines can be modelled, simulated and displayed. ARAS allows one to construct instruction pipelines by preparing various configuration files. Using these files and a number of benchmark programs, performance of the instruction pipelines can be obtained. The performance of asynchronous instruction pipelines can also be compared to synchronous case. Thus, one can decide the optimal design for instruction pipelines in asynchornous or synchronous cases and explore the deisng space of asynchronous instruction pipeline architectures.

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Extending Atm Networks For Efficient Reliable Multicast, Jonathan S. Turner Jan 1996

Extending Atm Networks For Efficient Reliable Multicast, Jonathan S. Turner

All Computer Science and Engineering Research

One of the important features of ATM networks is their ability to support multicast communications. This facilitates the efficient distribution of multimedia information streams (such as audio and video) to large groups of receivers (potentially millions). Because ATM networks do not provide reliable delivery mechanisms, it is up to end systems to provide end-to-end reliability where it is needed. While this is straightforward for point-to-point virtual circuits, it is more difficult for one-to many and many-to-mamy virtual circuits. In this report, we propose some minimal extensions to the hardware of ATM switches that enables end systems to implement reliable multicast …

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A Pilot Study Of Speech And Pen User Interface For Graphical Editing, Karl E. Schmidt Jan 1996

A Pilot Study Of Speech And Pen User Interface For Graphical Editing, Karl E. Schmidt

All Computer Science and Engineering Research

As computer size continues to decrease and new user interface technologies become more ubiquitous, the conventional keyboard and mouse input interfaces are becoming harder to design into newer machines and less practical for use in some applications. The pen is one input technology more suited for the upcoming generation of smaller computers using direct manipulation interfaces. However, a pen-only user interface relies on continuous gesture and handwriting tecognizers that are often slow, inaccurate, and error prone for command and text entry. Speech recognition is an input modality that can input commands quickly and potentially be a fast text entry mechanism, …

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Mobile Unity: Reasoning And Specification In Mobile Computing, Gruia-Catalin Roman, Peter J. Mccann Jan 1996

Mobile Unity: Reasoning And Specification In Mobile Computing, Gruia-Catalin Roman, Peter J. Mccann

All Computer Science and Engineering Research

Mobile computing represents a major point of departure from the traditional distributed computing paradigm. The potentially very large number of independent computing units, a decoupled computing style, frequent disconnections, continuous position changes, and the location-dependent nature of the behavior and communication patterns present designers with unprecedented challenges in the areas of modularity and dependability. So far, the literature on mobile computing is dominated by concerns having to do with the development of protocols and services. This paper complements this perspective by considering the nature of the underlying formal models that will enable us to specify and reason about such computations. …

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Alchourron's Defeasible Conditionals And Defeasible Reasoning, Fernando Tohme, Ronald P. Loui Jan 1996

Alchourron's Defeasible Conditionals And Defeasible Reasoning, Fernando Tohme, Ronald P. Loui

All Computer Science and Engineering Research

No abstract provided.

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Supporting Dis Applications Using Atm Multipoint Connection Caching, Anshul Kantawala, Guru Parulkar, John Dehart, Ted Marz Jan 1996

Supporting Dis Applications Using Atm Multipoint Connection Caching, Anshul Kantawala, Guru Parulkar, John Dehart, Ted Marz

All Computer Science and Engineering Research

This report describes an ATM Multipoint Connection Caching strategy (AMCC) to control the explosive growth of traffic within the network and at an endpoint in a large Distributed Interactive Simulation (DIS) application such as a battlefield simulation. For very large DIS applications with 100,000 entities, the current method of broadcasting information among entities will no longer be feasible due to computational and network bandwidth limitations. Our scheme divides the simulation space into grids and each grid square or a set of grid squares forms a multicast group. Entities join the groups within their perception range and thus, they receive state …

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Application Of Autoregressive Moving Average Linear Prediction Filters To The Characterization Of Solar Wind-Magnetosphere Coupling, Carter N. Borst Jan 1996

Application Of Autoregressive Moving Average Linear Prediction Filters To The Characterization Of Solar Wind-Magnetosphere Coupling, Carter N. Borst

Theses and Dissertations

Linear prediction filtering techniques have been used in studying the coupling processes between the solar wind and magnetosphere. The magnetosphere is a complex, dynamic system with at least two independent coupling methods for energy input, driven and unloading. Linear models were built and tested on the Bargatze data set, consisting of over 70 days of geomagnetic indices and solar wind data ordered in 34 intervals of increasing geomagnetic activity. Linear filtering techniques employing single-and multiple-input, autoregressive models predicted values of the magnetic index AL from solar wind data. The impulse response curves of the AL-coupling function groups showed amplitude peaks …

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The Distributed Array Descriptor For A Pcrc Hpf Compiler Version 2.0 Sccs-770d, Bryan Carpenter, James Cowie, Donald Leskiw, Xiaoming Li Jan 1996

The Distributed Array Descriptor For A Pcrc Hpf Compiler Version 2.0 Sccs-770d, Bryan Carpenter, James Cowie, Donald Leskiw, Xiaoming Li

Northeast Parallel Architecture Center

We describe a distributed array descriptor that can be used by a runtime supporting HPFlike compilers. This descriptor captures all five types of alignment and BLOCK and CYCLIC distribution as defined in HPF specification. In essence, this descriptor does not distinguish whole array and array sections. Prior to this version, we had versions 1.0, 1.1, and 1.2. This version is not only an update of previous versions, but more importantly it also directly reflects our current practice in an HPF compilation effort.

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A Review Of Commercial And Research Cluster Management Software, Mark Baker, Geoffrey C. Fox, Hon W. Yau Jan 1996

A Review Of Commercial And Research Cluster Management Software, Mark Baker, Geoffrey C. Fox, Hon W. Yau

Northeast Parallel Architecture Center

In the past decade there has been a dramatic shift from mainframe or ‘host-centric’ computing to a distributed ‘client-server’ approach. In the next few years this trend is likely to continue with further shifts towards ‘network-centric’ computing becoming apparent. All these trends were set in motion by the invention of the mass-reproducible microprocessor by Ted Hoff of Intel some twenty-odd years ago. The present generation of RISC microprocessors are now more than a match for mainframes in terms of cost and performance. The long-foreseen day when collections of RISC microprocessors assembled together as a parallel computer could outperform the vector …

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An Application Perspective On High-Performance Computing And Communications, Geoffrey C. Fox Jan 1996

An Application Perspective On High-Performance Computing And Communications, Geoffrey C. Fox

Northeast Parallel Architecture Center

We review possible and probable industrial applications of HPCC focusing on the software and hardware issues. Thirty-three separate categories are illustrated by detailed descriptions of five areas -- computational chemistry; Monte Carlo methods from physics to economics; manufacturing; and computational fluid dynamics; command and control; or crisis management; and multimedia services to client computers and settop boxes. The hardware varies from tightly-coupled parallel supercomputers to heterogeneous distributed systems. The software models span HPF and data parallelism, to distributed information systems and object/data flow parallelism on the Web. We find that in each case, it is reasonably clear that "HPCC works …

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Snap, Crackle, Webwindows!, Geoffrey C. Fox, Wojtek Furmanski Jan 1996

Snap, Crackle, Webwindows!, Geoffrey C. Fox, Wojtek Furmanski

Northeast Parallel Architecture Center

We elaborate the SNAP---Scalable (ATM) Network and (PC) Platforms---view of computing in the year 2000. The World Wide Web will continue its rapid evolution, and in the future, applications will not be written for Windows NT/95 or UNIX, but rather for WebWindows with interfaces defined by the standards of Web servers and clients. This universal environment will support WebTop productivity tools, such as WebWord, WebLotus123, and WebNotes built in modular dynamic fashion, and undermining the business model for large software companies. We define a layered WebWindows software architecture in which applications are built on top of multi-use services. We discuss …

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Exploration Of Emerging Hpcn Technologies For Web-Based Distributed Computing, Hon W. Yau, Alvin Leung, Wojtek Furmanski, Geoffrey C. Fox Jan 1996

Exploration Of Emerging Hpcn Technologies For Web-Based Distributed Computing, Hon W. Yau, Alvin Leung, Wojtek Furmanski, Geoffrey C. Fox

Northeast Parallel Architecture Center

The surge in the popularity of the World Wide Web (WWW) has corresponded to a decreasing market for specialised high performance computers. This paper discusses how, by making use of technology developed from the broader end of the computing pyramid, much of the past decade's work in distributed computing can be realised in the context of the larger WWW market. Not only do these new technologies offer fresh possibilities, but their pace of development is unlikely to be matched by the traditional high performance research community. A motivating application, discussions of the pertinent emerging technologies, and NPAC's investigations of them, …

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