Open Access. Powered by Scholars. Published by Universities.®
- Institution
- Keyword
-
- College of Engineering and Computer Science (10)
- Computer Science (10)
- Engineering (10)
- Newsletters (10)
- Science news (10)
-
- Technical writing (10)
- Information dissemination (4)
- Online systems (4)
- Document storage (3)
- Information systems (3)
- Information retrieval (2)
- Technology transfer (2)
- World Wide Web (2)
- Architecture (1)
- Books (1)
- Client server systems (1)
- Computer information security (1)
- Computer science education (1)
- Constraint database (1)
- Constraint object (1)
- Electronic data processing -- Distributed processing (1)
- Hypertext systems (1)
- Information (1)
- Information transfer (1)
- Internets (1)
- Memory management (Computer science) (1)
- Multithreaded (1)
- NASA (1)
- NASA programs (1)
- Object-oriented methods (Computer science) (1)
- Publication
- Publication Type
Articles 31 - 58 of 58
Full-Text Articles in Computer Engineering
Self-Stabilization By Counter Flushing, George Varghese
Self-Stabilization By Counter Flushing, George Varghese
All Computer Science and Engineering Research
A useful way to design simple and robust protocols is to make them self-stabilitizing. We describe a simple technique for self-stabilization called counter flushign which is applicable to a number of distributed algorithms. A randomized version of counter flushing is shown to have extremely small expected stabilization time. We show how our technique helps to crisply understand and improve some previous distributed algorithms. Then we apply it to a variety of total algorithms for deadlock detection, propagation of information with feedback, resets and snapshots. Our stabilizing snapshot protocol has much better complexity than the previous stabilizing non-blocking snapshot protocol. Hence …
Practical Methods For Approximating Shortest Paths On A Convex Polytope In R3, John Hershberger, Subhash Suri
Practical Methods For Approximating Shortest Paths On A Convex Polytope In R3, John Hershberger, Subhash Suri
All Computer Science and Engineering Research
We propose a n extremely simple approximation scheme for computing shortest paths on the surface of a convex polytope in three dimensions. Given a convex polytope P with n vertices and two points p,q on its surface, let dp (p,q) denote the shortest path distance between p and q on the surface of P. Our algorithm produces a path of length at most 2 × dp(p,q) in time O(n). Extending this results, we can also compute ana pproximation of the shortest path tree rooted at an arbitrary point χ Є P in time O(n log n). In the approximate tree, …
An Evaluation Of The Pavane Visualization System, Kenneth C. Cox, Gruia-Catalin Roman
An Evaluation Of The Pavane Visualization System, Kenneth C. Cox, Gruia-Catalin Roman
All Computer Science and Engineering Research
The Pavane program visualization system is an implementation of the declarative paradigm of visualization. After a brief report on the status of the Pavane implementation, we present the results of an evaluation of the usability of Pavane. This evaluation is based on the use of Pavane by its developers to construct program visualizations, on its use in a classroom setting as a tool for examining executing programs, and on its application to some simple scientific visualizations.
Design Of A Large Scale Multimedia Server, Milind M. Buddhikot, Guru Parulkar, Jerome R. Cox Jr.
Design Of A Large Scale Multimedia Server, Milind M. Buddhikot, Guru Parulkar, Jerome R. Cox Jr.
All Computer Science and Engineering Research
Large scale multimedia storage servers will be an integral part of the emerging distributed multimedia computing infrastructure. However, given the modest rate of improvements in storage transfer rates, designing servers that meet the demands of multimedia applications is a challenging task that needs significant architectural innovation. Our research project, called Massively-parallel And Real-time Storage (MARS) architecture, is aimed at the design and prototype implementation of a large scale multimedia storage server. It uses some of the well-known techniques in parallel I/O, such as data striping and Redundant Arrays of Inexpensive Disks (RAID) and an innovative ATM based interconnect inside the …
Universal Continuous Media I/O: Design And Implementation, Charles D. Cranor, Gurudatta M. Parulkar
Universal Continuous Media I/O: Design And Implementation, Charles D. Cranor, Gurudatta M. Parulkar
All Computer Science and Engineering Research
The problem this paper addresses is how to modify an existing operating system's I/O subsystem to support new high-speed networks and high-bandwidth multimedia applications that will play an important role in future computing environments. The proposed I/O subsystem is called universal continuous media I/O (UCM I/O). This paper will cover the preliminary design of UCM I/O, some of the trade-offs and issues that need to be addressed in order to implement UCM I/O, and a summary of work in progress.
Learning One-Dimensional Geometric Patterns Under One-Sided Random Misclassification Noise, Paul W. Goldberg, Sally A. Goldman
Learning One-Dimensional Geometric Patterns Under One-Sided Random Misclassification Noise, Paul W. Goldberg, Sally A. Goldman
All Computer Science and Engineering Research
Developing the ability to recognize a landmark from a visual image of a robot's current location is a fundamental problem in robotics. We consider the problem of PAC-learning the concept class of geometric patterns where the target geometric pattern is a configuration of k points on the real line. Each instance is a configuration of n points on the real line, where it is labeled according to whether or not it visually resembles the target pattern. To capture the notion of visual resemblance we use the Hausdorff metric. Informally, two geometric patterns P and Q resemble each othe runder the …
Efficient Fair Queueing Using Deficit Round Robin, George Varghese, M. Shreedhar
Efficient Fair Queueing Using Deficit Round Robin, George Varghese, M. Shreedhar
All Computer Science and Engineering Research
Fair queuing is a technique that allows each flow passing through a network device to have fair share of network resources. previous schemes for fair queuing that achieved nearly perfect fairness were expensive to implement: specifically, the work required to process a packet in these schemes was O(log(n)), where n is the number of active flows. This is expensive at high speeds. On the other hand, cheaper approximations of fair queuing that have been reported in the literature exhibit unfair behavior. In this paper, we describe a new approximation of fair queuing, that we call Deficit Round Robin. Our scheme …
Trading Packet Headers For Packet Processing, George Varghese
Trading Packet Headers For Packet Processing, George Varghese
All Computer Science and Engineering Research
In high speed networks, packet processing is relatively expensive while bandwidth is cheap. This begs the question: what fields can be added to packets to make packet processing easier? By exploring this question, we device a number of novel mechanisms to speed up packet processing. With the advent of new standards for hte Data Link, Network, and Transport lyaers, we believe there is an opportunity to apply these techniques to improve the performance of real protocols. First, we suggest adding a data manipulation header to an easily accessible portion of each packet. This header contains pointers to fields (in various …
Cmap, Ken Cox, John Dehart
Cmap, Ken Cox, John Dehart
All Computer Science and Engineering Research
This document specifies a Connection Management Access Protocol (CMAP) for call management in high-speed packet switched networks. We target CMAP to networks employing the Asynchronous Transfer Mode (ATM) communication standard. CMAP specifies the access procedues exercised by network clients to manipulate multipoint calls; it is thus a User-Network Interface (UNI) signalling protocol. We define a multipoint call as a group of multipoint connections. A multipoint connection is a communication channel between two or more clients or endpoints of the network, where all data sent by one client is received by all other clients who have elected to receive. A point-to-point …
Cell Tracking Using A Distributed Algorithm For 3d Image Segmentation, Vikas Awasthi, Keith W. Doolittle, Guru Parulkar, James G. Mcnally
Cell Tracking Using A Distributed Algorithm For 3d Image Segmentation, Vikas Awasthi, Keith W. Doolittle, Guru Parulkar, James G. Mcnally
All Computer Science and Engineering Research
We have developed and tested an automated method for simultaneous 3D tracking of numerous, flourescently-tagged cells. The procedure uses multiple thresholding to segment individual cells at a starting timepoint, and then iteratively applies a template-matching algorithm to locate a particular cell's position at subsequent time points. To speed up the method, we have developed a distributed implementation in which template matching is carried out in parallel on several different server machines. The distributed implementation showed a monotonic decrease in response time with increasing number of servers (up to 15 tested), demonstrating that the tracking algorithm is well suited to parallelization, …
Efficient Quality Of Service Support In Multimedia Computer Operating Systems, Raman Gopalakrishna, Guru M. Parulkar
Efficient Quality Of Service Support In Multimedia Computer Operating Systems, Raman Gopalakrishna, Guru M. Parulkar
All Computer Science and Engineering Research
This report describes our approach towards providing quality of service (QoS) guarantees for network communication within the endsystems to support multimedia applications. We first address the problem of QoS specification by identifying a set of application classes and their QoS parameters that cover the communication requirements of most applications. We then describe the QoS mapping problem, and show how requirements for resources (such as the CPU, the network interface adaptor and network connections) can be automatically derived from the application QoS parameters. We then deal with the QoS enforcement issue in which we describe techniques for scheduling protocol processing threads …
Morphing Binary Trees, John Hershberger, Subhash Suri
Morphing Binary Trees, John Hershberger, Subhash Suri
All Computer Science and Engineering Research
We investigate the problem of transforming one binary tree into another by rotatoins, subject to certain weight ocnstraints on the nodes of the trees. These constraints arise in the problem of "morphing" one simple polygon to another simple polygon by continuous deformatinos (translations and scalings) that preserve the turn angles and the simplicity of the polygon; the two polygons must have the same sequence of turn angles. Our main theorem is that two arbitrary n-leaf binary trees satisfying our weight constraint can be morphed into each other with O(n log n) rotations. Furthermore, we also present an O(n log n) …
High-Performance Training Of Feedforward & Simple Recurrent Networks, Barry L. Kalman, Stan C. Kwasny
High-Performance Training Of Feedforward & Simple Recurrent Networks, Barry L. Kalman, Stan C. Kwasny
All Computer Science and Engineering Research
TRAINREC is a system for training feedforward and recurrent neural networks that incorporates several ideas. It uses the conjugate-gradient method which is demonstrably more efficient than traditional backward error propagation. We assume epoch-based training and derive a new error function having several desirable properties absent from the traditional sum-of-squared-error function. We argue for skip (shortcut) connections where appropriate and the preference for a sigmoidal yielding values over the [-1,1] interval. The input feature space is often over-analyzed, but by using singular value decomposition, input patterns can be conditioned for better learning often with a reduced number of input units. Recurrent …
Catching Up With The Networks: Host I/O At Gigabit Rates, Zubin D. Dittia, Jerome R. Cox Jr., Guru M. Parulkar
Catching Up With The Networks: Host I/O At Gigabit Rates, Zubin D. Dittia, Jerome R. Cox Jr., Guru M. Parulkar
All Computer Science and Engineering Research
The last few years have seen network data rates skyrocket from a few Mbps to a Gbps or more. However, a lack of integration of the host-netowrk interface, the operating system, and network protocols has resulted in end-applications seeing only a small fraction of this total bandwidth being available for data transfer. The emergence of demanding applications in the realms of multimedia and virtual reality provides further impetus in the drive to overcome this problem. In this paper, we present the design of a high performance ATM host-network interface for workstations and servers that can support a bidirecitonal sustained data …
Reasoning About Places, Times, And Actions In The Presence Of Mobility, C. Donald Wilcox, Gruia-Catalin Roman
Reasoning About Places, Times, And Actions In The Presence Of Mobility, C. Donald Wilcox, Gruia-Catalin Roman
All Computer Science and Engineering Research
The current trend toward portable computing systems (e.g., cellular phones, laptop computers) brings with it the need for a new paradigm for thinking about designing distributed applications. We introduce the term mobile to refer to distributed systems that include moving, autonomous agents which loosely cooperate to accomplish a tastk. The fluid nature of hte interconnections between components in a mobile system provides new challenges and new opportunities for the research community. While we do not propsoe to have fully grasped the consequences of these systems, we believe that the notions of place, time, and action will be central in any …
Boxgraph: A Two-Dimensional Visual Computation Model, Takayuki Dan Kimura, Timothy B. Brown
Boxgraph: A Two-Dimensional Visual Computation Model, Takayuki Dan Kimura, Timothy B. Brown
All Computer Science and Engineering Research
Traditional computation models such as Turing machines, lambda-calculus, Markov's normal algorithms, are not suitable models for visual programming languages because they are all based on one-dimensional text strings and visual programming uses two-dimensional graphic diagrams. We propose a two-dimensional computation model, called Boxgraph, that requires no text. The syntax of the model consists of nested boxes connected by arrows, and the semantics consists of dataflow and the concept of consistency. The expressive power of the model is demonstrated by constructing representations of a binary full adder, the Fibonacci function, and the GCD function. The model, with a small extension to …
An Incremental Distributed Algorithm For Computing Biconnected Components, Bala Swaminathan, Kenneth J. Goldman
An Incremental Distributed Algorithm For Computing Biconnected Components, Bala Swaminathan, Kenneth J. Goldman
All Computer Science and Engineering Research
This paper describes a distributed algorithm for computing the biconnected components of a dynamically changing graph. Our algorithm has a worst case communication complexity of O(b + c) messages for an edge insertion and O(b' + c) messages for an edge removal, and a worst case time complexity of O(c) for both operations, where c is the maximum number of biconnected components in any of the connected components during the operation, b is the number of nodes in the biconnected component containing the new edge, and bprime is the number of nodes in the biconnected component in which the update …
Speculative Computation: Overcoming Communication Delays In Parallel Algorithms, Vasudha Govindan, Mark A. Franklin
Speculative Computation: Overcoming Communication Delays In Parallel Algorithms, Vasudha Govindan, Mark A. Franklin
All Computer Science and Engineering Research
Communication latencies and delays are a major source of performance degradation in parallel computing systems. It is importnat to "mask" these communication delays by overlapping them with useful computation in order to obtain good parallel performance. This paper proposes speculative computation as a technique to mask communication latencies. Speculative computation is discussed in the context of synchronous iterative algorithms. Processors speculate the contents of messages that are not hyet received and perform computation based on the speculated values. When the messages are received, they are compared with the speculated values and, if the error is unacceptable, the resulitng computation is …
Pipelined And Superscalar Architectures In Clocked And Asynchronous Environments, Mark A. Franklin, Tienyo Pan
Pipelined And Superscalar Architectures In Clocked And Asynchronous Environments, Mark A. Franklin, Tienyo Pan
All Computer Science and Engineering Research
In this paper, a set of simple, general, yet practical performance models for RISC architectures are developed. These models apply to a wide range of systems that include both pipelined and superscalar systems operating in either clocked or asynchronous environments. The models permit quantitative evaluation of various design choices (e.g., the number of pipelines in the system, the pipeline depth, and the choice between clocked and asynchronous methodologies) as functions of technology parameters, environmental operating parameters, and pipeline function characteristics. Design curves are presented indicating optimal pipeline depth and number of pipelines to employ under various conditions.
Distributed Data Layout, Scheduling And Playout Control In A Large Scale Multimedia Storage Server, Milind M. Buddhikot, Guru Parulkar
Distributed Data Layout, Scheduling And Playout Control In A Large Scale Multimedia Storage Server, Milind M. Buddhikot, Guru Parulkar
All Computer Science and Engineering Research
No abstract provided.
Distributed Multimedia Systems Research Prospectus, Jonathan Turner
Distributed Multimedia Systems Research Prospectus, Jonathan Turner
All Computer Science and Engineering Research
Distributed multimedia computing and communiation systems combine computer systems, networks and distributed software to facilitate applications that enable and enhance collaborative work, direct interpersonal communication, remote access to information and real-time presentation of information from a variety of sources. Over the next decade, we expect such systems to become central to the infrastructure of our increasingly information-driven society. This prospectus describes a program of research being pursued within the Computer and Communications Research Center of Washington University and the Departments of Computer Science and Electrical Engineering. This program seeks to promote the creation of effective distributed multimedia systems and develop …
Proposal For Research Distribution Of Gigabit Network Technology, Jonathan Turner
Proposal For Research Distribution Of Gigabit Network Technology, Jonathan Turner
All Computer Science and Engineering Research
In 1993, APRA funded a major program at Washingotn University to create gigabit networking technology and create a gigabit testbed based on this technology. This program is now nearing the end of its first year and is making excellent proress towards its research and technical objectives. This note a proposes a program that would lead to the export of this technology to research groups in networking and gigabit applications with an interest in using it to further their own research activities.
A Strategy For Electronic Dissemination Of Nasa Langley Technical Publications, Donna G. Roper, Mary K. Mccaskill, Scott D. Holland, Joanne L. Walsh, Michael L. Nelson, Susan L. Adkins, Manjula Y. Ambur, Bryan A. Campbell
A Strategy For Electronic Dissemination Of Nasa Langley Technical Publications, Donna G. Roper, Mary K. Mccaskill, Scott D. Holland, Joanne L. Walsh, Michael L. Nelson, Susan L. Adkins, Manjula Y. Ambur, Bryan A. Campbell
Computer Science Faculty Publications
To demonstrate NASA Langley Research Center's relevance and to transfer technology to external customers in a timely and efficient manner, Langley has formed a working group to study and recommend a course of action for the electronic dissemination of technical reports (EDTR). The working group identified electronic report requirements (e.g., accessibility, file format, search requirements) of customers in U.S. industry through numerous site visits and personal contacts. Internal surveys were also used to determine commonalities in document preparation methods. From these surveys, a set of requirements for an electronic dissemination system was developed. Two candidate systems were identified and evaluated …
The World Wide Web And Technology Transfer At Nasa Langley Research Center, Michael L. Nelson, David J. Bianco
The World Wide Web And Technology Transfer At Nasa Langley Research Center, Michael L. Nelson, David J. Bianco
Computer Science Faculty Publications
NASA Langley Research Center (LaRC) began using the World Wide Web (WWW) in the summer of 1993, becoming the first NASA installation to provide a Center-wide home page. This coincided with a reorganization of LaRC to provide a more concentrated focus on technology transfer to both aerospace and non-aerospace industry. Use of the WWW and NCSA Mosaic not only provides automated information dissemination, but also allows for the implementation, evolution and integration of many technology transfer applications. This paper describes several of these innovative applications, including the on-line presentation of the entire Technology Opportunities Showcase (TOPS), an industrial partnering showcase …
Precision Measurement Of The Ds*+-Ds+ Mass Difference, Brown, D.; Et Al., M. Thulasidas
Precision Measurement Of The Ds*+-Ds+ Mass Difference, Brown, D.; Et Al., M. Thulasidas
Research Collection School Of Computing and Information Systems
We have measured the vector-pseudoscalar mass splitting M(D*+s)-M(D+s)=144.22±0.47±0.37 MeV significantly more precisely than the previous world average. We minimize the systematic errors by also measuring the vector-pseudoscalar mass difference M(D*0)-M(D0) using the radiative decay D*0→D0γ, obtaining [M(D*+s)-M(D+s)]-[M(D*0)-M(D0)] =2.09±0.47±0.37 MeV. This is then combined with our previous high-precision measurement of M(D*0)-M(D0), which used the decay D*0→D0π0. We also measure the mass difference M(D+s)-M(D+)=99.5±0.6±0.3 MeV, using the φπ+ decay modes of the D+s and D+ mesons.
Measurement Of Cabibbo-Suppressed Decays Of The Τ Lepton, Battle, M.; Et Al., M. Thulasidas
Measurement Of Cabibbo-Suppressed Decays Of The Τ Lepton, Battle, M.; Et Al., M. Thulasidas
Research Collection School Of Computing and Information Systems
No abstract provided.
Observation Of A New Charmed Strange Meson, Kubota, Y.; Et Al., M. Thulasidas
Observation Of A New Charmed Strange Meson, Kubota, Y.; Et Al., M. Thulasidas
Research Collection School Of Computing and Information Systems
No abstract provided.
Multithreaded Computer Architecture: A Summary Of The State Of The Art, Robert Iannucci, Guang Gao, Robert Halstead, Burton Smith
Multithreaded Computer Architecture: A Summary Of The State Of The Art, Robert Iannucci, Guang Gao, Robert Halstead, Burton Smith
Robert A Iannucci
No abstract provided.