Engineering Commons^™

Exact Learning Of Discretized Geometric Concepts, Nader H. Bshouty, Paul W. Goldberg, Sally A. Goldman, H. David Mathias

All Computer Science and Engineering Research

We first present an algorithm that uses membership and equivalence queries to exactly identify a discretized geometric concept defined by the unioin of m axis-parallel boxes in d-dimensional discretized Euclidean space where each coordinate can have n discrete values. This algorithm receives at most md counterexamples and uses time and membership queries polynomial in m and log(n) for any constant d. Furthermore, all equivalence queries can be formulated as the union of O(mdlog(m)) axis-parallel boxes. Next, we show how to extend our algorithm to efficiently learn, from only equivalence queries, any discretized geometric concept generated from any number of halfspaces …

Learning From A Consistently Ignorant Teacher, Michael Frazier, Sally Goldman, Nina Mishra, Leonard Pitt

All Computer Science and Engineering Research

One view of computational learning theory is that of a learner acquiring the knowledge of a teacher. We introduce a formal model of learning capturing the idea that teachers may have gaps in their knowledge. The goal of the learner is still to acquire the knowledge of the teacher, but now the learner must also identify the gaps. This is the notion of learning from a consistently ignorant teacher. We consider the impact of knowledge gaps on learning, for example, monoton DNF and d-dimensional boxes, and show that leraning is still possible. Negatively, we show that knowledge gaps make learning …

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

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, …

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 …

Visual Specification Of Interprocess And Intraprocess Communication, T. Paul Mccartney, Kenneth J. Goldman

All Computer Science and Engineering Research

We present a visual specification language for constructing distributed applications and their direct manipulation graphical user interfaces. Each distributed application consists of a collection of independent modules and a configuration of logical connections that define communication among the data interfaces of the modules. Our specification language uses a single visual mechanism that allows end-users to define interprocess communication among distributed modules and to define intraprocess communication among objects within a module. This seamless specification provides a general encapsulation/abstraction mechanism and is designed to support dynamic change to the communication structure. User interfaces are completely decoupled from the module(s) they control.

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 …

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 …

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.

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) …

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.

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 …

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.

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

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 …

Production Quality Video Over Broadband Networks: A Description Of The System And Two Interactive Applications, William D. Richard, Jerome R. Cox Jr., A. Maynard Engebretson, Jason Fritts And Brian L. Gottlieb And Craig Horn

All Computer Science and Engineering Research

The Washington University MultiMedia eXplorer (MMX) is a complete, host-independent multimedia system capable of transmitting and receiving JPEG-compressed video, CD-quality audio, and high-resolution radiographic images over the Washington University broadband ATM network. If the host is equipped with an ATM interface card, normal network traffic can be supported via an ATM extension port on the MMX. The major components of the MMX are an ATMizer and three multimedia channels. The ATMizer implements the host interface, the interface to the ATM network, and hte interface to the three multimdeia channels. This paper describes the architecture of the MMX, the software used …

Visual Presentation Of Software Specifications And Designs, Gruia-Catalin Roman, Delbert Hart, Charles Calkins

All Computer Science and Engineering Research

Formal methods hold the promise for high dependability in the design of critical software. However, software engineers who employ formal methods need to communicate their design decisions to users, customers, managers, and collegues who may not be in a position to acquire a full understanding of the formal notation being used. Visualizations derived from formal specifications and designs must be able to convey the required information precisely and reliably without the use of formal notation. This paper discusses a design methodology which attempts to integrate a design methodology based upon specification and program refinement with a state-of-the-art approach to rapid …

Performance Comparison Of Asynchronous Adders, Mark A. Franklin, Tienyo Pan

All Computer Science and Engineering Research

In asynchronous systems, average function delays principally govern overall throughput. This paper compares the performance of six adder designs with respect to their average delays. Our results show that asynchronous addres (32 or 64-bits) with a hybrid structure (e.g., carry-select addres) run 20-40% faster than simple ripple-carry addres. Hybrid adders also outperform high-cost, strictly synchronous conditional-sum adders.

An Application-Oriented Error Control Scheme For High Speed Networks, Fengmin Gong, Gurudatta Parulkar

All Computer Science and Engineering Research

Many new network applications demand interprocess communication (IPC) services that are not supported by existing transport protocol mechanisms. Large bandwidth-delay products of high-speed networks also render the existing control mechanisms such as flow and error control less efficient. In particular, new error control schemes that can provide variable degrees of error recovery according to the applications requirements are needed. This paper presents the design, evaluation, and implementation of an application-oriented error control scheme that is aimed at supporting efficient IPC in high-speed networking environments. Our results show that the proposed error control scheme allows effective control of trade-off between the …

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, …

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 …

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 …

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.

Learning And Teaching Of Boolean And Geometric Classes, H. David Mathias

All Computer Science and Engineering Research

We consider the concept classes of DNF formulas and unions of discretized, axis-parallel d-dimensional boxes in discretized d-dimensional space with respect to several different learning models. In the model of learning with queries we present an algorithm to learn unions of boxes. We introduce a model of teaching that prevents illicit communication between the teacher and the leaner but that captures the intuitive aspect of teaching: a learner should perform at least as well with a cooperative teacher as with an adversarial teacher. We propose the study of teaching of DNF formulas and unions of boxes in this model. We …

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 …

Connection Management In Reconfigurable Distributed Systems, Bala Swaminathan

All Computer Science and Engineering Research

The Programmer's Playground takes a new approach to simplifying and supporting the construction of distributed applications. The approach, called I/O abstraction, separates the description of a system's communication structure from the descriptions of its computational components so that software modules written in existing programming languages cna be integrated flexibly and dynamically by both programmers and end-users. This separation is achieved by estabishing logical connectinos among the data interfaces of independent software modules. The logical connections provide a uniform high-level view of communication for both discrete and continuous data. The I/O abstraction approach inherits ideas from the I/O automaton model, a …

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.

Programmable Analog Array Circuit, Marek Perkowski, Edmund Pierzchala

Electrical and Computer Engineering Faculty Publications and Presentations

There is disclosed a programmable analog or mixed analog/ digital circuit. More particularly, this invention provides a circuit architecture that is ?exible for a programmable electronic hardWare device or for an analog circuit Whose input and output signals are analog or multi-valued in nature, and primarily continuous in time. There is further disclosed a design for a current-mode integrator and sample-and-hold circuit, based upon Miller effect.

Identification Of Tire Leachate Toxicants And A Risk Assessment Of Water Quality Effects Using Tire Reefs In Canals, S. M. Nelson, G. Mueller, D. C. Hemphill, U.S. Bureau Of Reclamation

Publications (WR)

Cover is an important component of aquatic habitat and fisheries management. Fisheries biologists often try to improve habitats through the addition of natural and artificial material to improve cover diversity and complexity. Habitat-improvement programs range from submerging used Christmas trees to more complex programs using sophisticated artificial habitat modules. Used automobile tires have been employed in the large scale construction of reefs and fish attractors in marine environments and to a lesser extent in freshwater and have been recognized as a durable, inexpensive and long-lasting material which benefits fishery communities.

Recent studies by the U.S. Bureau of Reclamation have quantified …

Comparison Of Self Pulsation In Multisection Lasers With Distributed Feedback And Intracavity Satuarable Absorbers, P. Phelan, D. Mcdonald, A. Egan, Joe Hegarty, R. O'Dowd, Gerald Farrell, S. Lingren

Articles

The authors report a comparison of the self-pulsing characteristics of two types of semiconductor laser. They show that the self-pulsing frequency of the DFB laser is decoupled from the resonance frequency. They discuss the various characteristics, their significance in relation to optical synchronisation, and use the results to suggest a possible explanation for the mechanism for self-pulsation in the DFB laser.