Computer Engineering Commons^™

Real-Time Upcalls: A Mechanism To Provide Real-Time Processing Guarantees, Raman Gopalakrishna, Guru M. Parulkar

All Computer Science and Engineering Research

Real-time upcalls (RTUs) are an operating systems mechanism that can be used by applications to efficiently schedule code segments (or handlers) that must execute periodically. While the mechanism was conceibed to support protocol processing with quality-of-service guarantees for networked multimedia applicatoins it is general enough to be applicable in other domains like real-time image processing. Until now real-time threads have been the only mechanism for implementing protocols in user space with QoS guarantees. The RTU mechanism avoids the implementation complexity of the thread based approach while retaining its ability to ensure real-time behavior. In addition, our design simplifies protocol code, …

Load Balance Properties Of Distributed Data Layouts For Clustered Mod Servers, Milind M. Buddhikot, Guru Parulkar

All Computer Science and Engineering Research

Large scale storage servers that provide location transparent, interactive access to hundreds or thousands of concurrent, independent clients will be important components of hte furture information super-highway infrastructure. Two key requirements of such servers are as follows: support high parallelism and concurrency in data access to allow large number of access to the same or different data. Second, support independent interactive playout control operations such as fast-forward, rewind, slow-play, pause, resume, random access etc. with minimal latency. This paper assumes a distributed storage server architecture consisting of several high performance storage nodes interconnected by a high speed desk area network …

Hart's Critics On Defeasible Concepts And Ascriptivism, Ronald P. Loui

All Computer Science and Engineering Research

Hart's "Ascription of Responsibility and Rights" is where we find perhaps the first clear pronouncement of defeasibility and the technical introduction of the term. The paper has been criticised, disavowed, and never quite fully redeemed. Its lurid history is now being used as an excuse for dismissing the importance of defeasibility. Quite to the contrary, Hart's introduction of defeasibility has uniformly been regarded as the most agreeable part of the paper. The critics' wish that defeasibility could be better expounded along the lines of a Wittgensteinian game-theoretic semantics has largely been fulfilled. Even the most contentious part of the paper, …

Efficient Demultiplexing Of Network Packets By Automatic Parsing, Mahesh Jayaram, Ron K. Cytron

All Computer Science and Engineering Research

Packet filters are a mechanism for efficiently demultiplexing network packets to application endpoints. There is currently no general, formal specification method for packet filters that allows for easy or efficient composition of specifications. In this paper we present an automatic approach that achieves all of these goals. We approach packet filter specification as a language recognition problem: each filter is represented by a context-free grammar, whose language is the set of packets the filter should accept. Thus, packet filters can be formulated through a general, well defined specification; further, the grammar-based approach simplifies filter composition, which is essential where scalability …

Design Of A Tool For Rapid Prototyping Of Communication Protocols, Aniruddha Gokhale, Ron Cytron, George Varghese

All Computer Science and Engineering Research

We present a new tool for automatically generating prototypes of communication protocols on a wide variety of platforms. Our goal is to reduce design time, enhance portability, and accommodate optimizations automatically. Users of the tool are required to provide an abstract implementation of the protocol in C++ without worrying about the underlying operating system specific system calls. Instead, the user employs high-level interface functions provided by the tool to interact with the underlying operating system. Users also need not worry about complex packet formats that involve fields of various bit and byte lengths. Instead, they use simple C/C++ struct declarations …

Self-Stabilization By Window Washing, Adam M. Costello, 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 new general technique for self-stabilization called window washing. We apply this technique to generalized sliding window protocols that work on a number of topologies. This results in simple, efficient, and self-stabilizing protocols. As far as we know, both window washing and generalized sliding window protocols are new ideas. Our protocols can be used for data links, reliable broadcast, and flow control.

Distributed Radiological Multimedia Conferencing, Naeem Bari

All Computer Science and Engineering Research

Distributed Radiological Multimedia Conference (DRMC) is a collaborative imaging/multimedia conferencing tool which allows geographically separated physicians to confer over a shared projection radiograph. DRMC utilizes the advantages of high bandwidth and scalability offered by the new Asynchronous Transfer Mode (ATM) network technology. This application is customized for the high quality of displayed images and rapid response to user requests. It allows conferees to: share a common radiograph; each possess an independently controlled globally visible cursor; be able to point to and outline areas on the image to bring it to the other conferees' attention; and see and hear each other …

A General Matrix Iterative Model For Dynamic Load Balancing, Mark A. Franklin, Vasudha Govindan

All Computer Science and Engineering Research

Effective load balancing algorithms are crucial in fully realizing the performance potential of parallel computer systems. This paper proposes a general matrix iterative model to represent a range of dynamic load balancing algorithms. The model and associated performance measures are used to evaluate and compare vairous load balancing algorithms and derive optimal algorithms and associated parameters for a given application and multiprocessor system. The model is parameterized to represent three load balancing algorithms - the random strategy, diffusion and complete redistribution algorithms. The model is validated by comparing the results with measured performance on a realistic workload. The parallel N-body …

Issues In Distributed Control For Atm Networks, Jonathan S. Turner

All Computer Science and Engineering Research

Asynchronous Transfer Mode (ATM) network technology is expected to become a central part of the emerging global information infrastructure. ATM networks introduce a number of features that distinguish them from earlier technologies and introduce new issues in network control. This paper offers a framework for precisely defining and analyzing alternative approaches to the distributed control of ATM networks and explores some of the key design issues through a series of examples. It is hoped that it will provide a useful foundation for researchers in networking and distributed computing interested in exploring these issues further and developing more complete solutions.

Synchronized Data Objects, Marin Bezic

All Computer Science and Engineering Research

Synchronized Data Objects (SDOs) are presented as a method of encapsulating, in the datatype definition, synchronization protocols that are used to control information exchange. SDOs are presented in the context of I/O abstraction, a programming model that seeks to separate communication from computation in order to support dynamic end-user configuration of distrivuted applications. SDOs can be used to implement a variety of synchronization paradigms, including remote invalidation, demand-driven data streams, remote procedure call, and promises. An implementation of SDOs is described in the context of The Programmers' Playground, a distributed application development environment that supports the I/O abstraction programming model. …

Euphoria Reference Manual, T. Paul Mccartney, Kenneth J. Goldman

All Computer Science and Engineering Research

No abstract provided.

Building Interactive Distributed Applications In C++ With The Programmers' Playground, Kenneth J. Goldman, T. Paul Mccartney, Ram Sethuraman, Bala Swaminathan And Todd Rogers

All Computer Science and Engineering Research

No abstract provided.

Maintaining High Throughput During Overload In Atm Switches, Jonathan S. Turner

All Computer Science and Engineering Research

This report analyzes two popular heuristics for ensuring packet integrity in ATM switching systems. In particular, we analyze the behavior of packet tail discarding, in order to understand how the packet level link efficiency is dependent on the rates of individual virtual circuits and the degre of the imposed overload. In addition, we study early packet discard and show that the queue capacity needed to achieve high efficiency under worst-case conditions grows with the number of virtual circuits and we determine the efficiency obtainable with more limited queue capacities. Using the insights from these analyses, extensions to early packet discard …

Distributed Debugging With I/O Abstraction, Andrew S. Koransky

All Computer Science and Engineering Research

This thesis presents a simple, yet powerful, set of mechanisms for testing and debugging distributed applications consisting of modules that communicate through well-defined data interfaces. The tools allow default or programmer-defined functions to be attached to various communication events so that particular data values at interesting points in the program are made available for testing and debugging. The debugging status of each component of the communication interface can be controlled separately so that various debugging information can be turned on and off during program execution. By attaching breakpoints to programmer-defined fucntions in a standard debugger, fine-grained examination of each module …

Time Variability While Training A Parallel Neural Net Network, Tina L. Seawell, Barry L. Kalman

All Computer Science and Engineering Research

The algorithmic analysis, data collection, and statistical analysis required to isolate the cause of time variability observed while an Elman style recurrent neural network is trained in parallel on a twenty processor SPARCcenter 2000 is described in detail. Correlations of system metrics indicate the operating system scheduler or an interaction of kernel processes is the most probable explanation for the variability.

Euphoria: End-User Construction Of Direct Manipulation User Interfaces For Distributed Applications, T. Paul Mccartney, Kenneth J. Goldman, David E. Saff

All Computer Science and Engineering Research

The Programmers' Playground is a software library and run-time system for creating distributed multimedia applications from collections of reusable software moduels. This paper presents the design and implementation of EUPHORIA, Playground's user interface management system. Implemented as a Playground module, EUPHORIA allows end-users to create direct manipulation graphical user interfaces (GUIs) exclusively through the use of a graphics editor. No programming is required. At run-time, attributes of the GUI state can be exposed and connected to external Playground modules, allowing the user to vosualize and directly manipulate state information in remote Playground modules. Features of EUPHORIA include real-time direct manipulation …

Optimizing Object Invocation Using Optimistic Incremental Specialization, Jon Inouye, Andrew P. Black, Charles Consel, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

To make object invocation efficient, it is important to minimize overhead. In general, overhead is incurred in order to maintain transparency; with the advent of mobile computer systems, persistence, increasing security and privacy concerns, transparency becomes more expensive and overhead is increasing. Invocation mechanisms maintain transparency by finding objects, choosing communication media, performing data translation into common formats (e.g., XDR), marshalling arguments, encrypting confidential data, etc. Performing all of these operations on every invocation would lead to unacceptable performance, so designers often avoid operations by specializing object invocation for more restricted environments. For example, the Emerald compiler performs several optimizations …

Adaptive Resonance Associative Map, Ah-Hwee Tan

Research Collection School Of Computing and Information Systems

This article introduces a neural architecture termed Adaptive Resonance Associative Map (ARAM) that extends unsupervised Adaptive Resonance Theory (ART) systems for rapid, yet stable, heteroassociative learning. ARAM can be visualized as two overlapping ART networks sharing a single category field. Although ARAM is simpler in architecture than another class of supervised ART models known as ARTMAP, it produces classification performance equivalent to that of ARTMAP. As ARAM network structure and operations are symmetrical, associative recall can be performed in both directions. With maximal vigilance settings, ARAM encodes pattern pairs explicitly as cognitive chunks and thus guarantees perfect storage and recall …

Redesigning The Bsd Callout And Timer Facilities, Adam M. Costello, George Varghese

All Computer Science and Engineering Research

We describe a new implementation of the BSD callout and timer facilities. Current BSD kernels take time proportional to the number of outstanding timers to set or cancel timers. Our implementation takes constant time to start, stop, and maintain timers; this leads to a highly scalable design that can support thousands of outstanding timers without much overhead. Unlike the existing implementation, our routines are guaranteed to lock out interrupts only for a small, bounded amount of time. We also extend the setitimer() interface to allow a process to have multiple outstanding timers, thereby reducing the need for users to maintain …

Formal Specification Of A Dynamically Configurable Distributed System, Ram Sethuraman, Kenneth J. Goldman

All Computer Science and Engineering Research

The Programmers' Playground is a programming environment that supports end-user construction of distributed multimedia applications. The system implements a new programming model that is based, in part, upon ideas from the formal I/O automaton model of Lynch and Tuttle. Important features of The Programmers' Playground are a separation of communication and computation and graphical support for dynamic reconfiguration. This paper provides a formal specification of the Playground programming model and runtime system in terms of the I/O automaton model on which it is based. Exploiting the compositionality properties of the I/O automaton model, the formal specification is describd as a …

Error Control For Continuous Media And Multipoint Applications, Christos Papadopoulos, Guru Parulkar

All Computer Science and Engineering Research

High-bandwidth multimedia applications pose new challenges to error control. These include the support of error control for Continuous Media (CM) streams and the scalable support of error control in multipoint applications where the number of participants is large. Current error control mechanisms provide no support for the above applications. In this report we present new error control mechanisms that provide the required support. Continuous media applications have strict timing requirements which greatly affect recovery. To support continuous media applications we have designed and implemented a point-to-point error control mechanism which features the following: (1) selective repeat retransmission, (2) conditional retransmission, …

User Interface Applications Of A Multi-Way Constraint Solver, T. Paul Mccartney

All Computer Science and Engineering Research

Constraints are widely recognized as a useful tool for user interface constructino. Through constraints, relationships among user interface components can be defined declaratively, leaving the task of relationship management to a constraint solver. Multi-way constraint solvers supporting constraint hierarchies provide a means to specify preferential constraint relationships with a dynamically changing computation flow, making them especially well suited to interactive user interfaces. However, previous such constraint solvers lack the ability to enforce inequalities or to effectively handle cyclic constraint relationships. These deficiencies limit the problems that could be solved using a constraint-based approach. This paper presents a new algorithm called …

Reliable Fifo Load Balancing Over Multiple Fifo Channels, Hari Adieseshu, Gurudatta M. Parulkar, George Varghese

All Computer Science and Engineering Research

Link striping algorithms are often used to overcome transmission bottlenecks in computer networks. However, traidtional striping algorithms suffer from two major disadvantages. They provide inadequate load sharing in the presence of variable length packets, and may result in non-FIFO delivery of data. We describe a new family of link striping algorithms that solve both problems. Our scheme applies to packets at any layer (physical, data, link, network, and transport) that work over multiple FIFO channels. We deal with variable sized packets by showing how a class of fair queueing algorithms can be converted into load sharing algorithms. Our transformation results …

An Efficient Signaling Structure For Atm Networks, Dakang Wu

All Computer Science and Engineering Research

As ATM becomes widely accepted as the communication standard for high speed networks, the signaling system structure and protocols that support ATM become more and more important. To support existing, future and unknown applications, the signalign system has to be very flexible and efficient. In this paper we define the signaling problem, present several possible signaling system structures, compare the advantages and disadvantages of these systems, and then we propose a new signaling system structure. The fundamental idea of the new signaling system is the logical separation of the signaling system structure from the underlying communication network, even though they …

Can Declared Strategy Voting Be An Effective Instrument For Group Decision-Making?, Lorrie Faith Cranor

All Computer Science and Engineering Research

The goal of this research is to determine whether declared strategy voting can be an effective tool for group decision-making. Declared strategy voting is a novel group decision-making procedure in which preference is specified using voting strategies - first-order mathematical functions that specify a choice in terms of zero or more parameters. This research will focus on refining the declared strategy voting concept, developing an accessible implementation of declared strategy voting that can be used for mock elections, assessing the potential impacts of declared strategy voting, and evaluating the effectiveness of declared strategy voting for group decision-making. This proposal describes …

An Oo Encapsulation Of Lightweight Os Concurrency Mechanisms In The Ace Toolkit, Douglas C. Schmidt

All Computer Science and Engineering Research

This paper describes the design of the ACE object-oriented thread encapsulation class library. The architecture of this class library is presented from an end-user and internal design perspective and several key design issues are discussed. Readers should gain an understanding of the overall design approach as well as the tradeoffs between various software quality factors such as performance, portability, and extensibility.

Production Of Excited Beauty States In Z Decays, D. Buskulic, Manoj Thulasidas

Research Collection School Of Computing and Information Systems

A data sample of about 3.0 million hadronic Z decays collected by the ALEPH experiment at LEP in the years 1991 through 1994, is used to make an inclusive selection of B hadron events.

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 10, Number 10, December 1994, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A fourteen page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 10, Number 9, November 1994, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A fourteen page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

Biofeedback Gait Training Auditory Vs. Visual Techniques, Timothy D. Hiemenz

Electrical & Computer Engineering Theses & Dissertations

Training lower extremity amputees to walk normally is quite a difficult task. Amputees must wear a prosthesis so they can walk at all. This allows them some mobility, but their walking pattern may be unnatural. If their gait is temporally asymmetric, they need to exert more energy to move about. This research was initiated to help lower extremity amputees to walk more efficiently using biofeedback gait training. Two types of feedback were developed and tested to determine which method gave the most understandable feedback, validating its use in a clinical setting.

A normal gait cycle uses the lower limbs to …