Digital Communications and Networking Commons^™

Navigation Satellite Selection Using Neural Networks, Daniel J. Simon, Hossny El-Sherief

Electrical and Computer Engineering Faculty Publications

The application of neural networks to optimal satellite subset selection for navigation use is discussed. The methods presented in this paper are general enough to be applicable regardless of how many satellite signals are being processed by the receiver. The optimal satellite subset is chosen by minimizing a quantity known as Geometric Dilution of Precision (GDOP), which is given by the trace of the inverse of the measurement matrix. An artificial neural network learns the functional relationships between the entries of a measurement matrix and the eigenvalues of its inverse, and thus generates GDOP without inverting a matrix. Simulation results …

Real-Time Communication In The Algorithm To Architecture Mapping Model, Somesh M. Varma

Electrical & Computer Engineering Theses & Dissertations

The objective of this thesis is to analyze schedules of communication resources to obtain deterministic and contention-free communication in the Algorithm To Architecture Mapping Model (ATAMM). In ATAMM, performance must be deterministic to guarantee meeting deadlines. It is difficult to achieve deterministic performance in the presence of contention during communication. This thesis develops new data-flow models to study and analyze different schedules of communication resources to achieve deterministic and contention-free communication. These models are the Synchronous Communication Marked Graph (SCMG) and the Asynchronous Communication Marked Graph (ACMG). The SCMG is based on message passing synchronous communication. It defines schedules for …

Thermal Effects On Y2O3:Eu3+ For Fiber Optic Temperature Sensing, Arnel C. Lavarias

Electrical & Computer Engineering Theses & Dissertations

Fiber optic methods have gained acceptance in the past several years as non­ intrusive optical techniques of measuring environmental variables, particularly under hostile conditions. Fiber optic temperature sensors are required for many applications which have a large operating range. One way to implement this sensor is to introduce rare earth-doped materials into a fiber showing temperature-dependent optical emission characteristics. The thermal effects on optical emission characteristics of Y₂O₃:Eu³⁺ were studied. The thermal broadening and temperature dependence of the lifetime (τ) of the 611.4 nm emission due to the ⁵D₀ ➔ 7F …

Computer Networks And The Teaching Of English As A Second Language: How Networks Affect Second Language Acquisition, Kirstin J. Reed-Perez

English Theses & Dissertations

No abstract provided.

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 …

World Wide Web Implementation Of The Langley Technical Report Server, Michael L. Nelson, Gretchen L. Gottlich, David J. Bianco

Computer Science Faculty Publications

On January 14, 1993, NASA Langley Research Center (LaRC) made approximately 130 formal, 'unclassified, unlimited' technical reports available via the anonymous FTP Langley Technical Report Server (LTRS). LaRC was the first organization to provide a significant number of aerospace technical reports for open electronic dissemination. LTRS has been successful in its first 18 months of operation, with over 11,000 reports distributed and has helped lay the foundation for electronic document distribution for NASA. The availability of World Wide Web (WWW) technology has revolutionized the Internet-based information community. This paper describes the transition of LTRS from a centralized FTP site to …

Electronic Document Distribution: Design Of The Anonymous Ftp Langley Technical Report Server, Michael L. Nelson, Gretchen L. Gottlich

Computer Science Faculty Publications

An experimental electronic dissemination project, the Langley Technical Report Server (LTRS), has been undertaken to determine the feasibility of delivering Langley technical reports directly to the desktops of researchers worldwide. During the first six months, over 4700 accesses occurred and over 2400 technical reports were distributed. This usage indicates the high level of interest that researchers have in performing literature searches and retrieving technical reports at their desktops. The initial system was developed with existing resources and technology. The reports are stored as files on an inexpensive UNIX workstation and are accessible over the Internet. This project will serve as …

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 …

Local Area Network Implementation At The 4950th Test Wing: A Study Of The Relationship Between Individual Factors And The Effectiveness Of A Local Area Network, Doyle F. Cone, David J. Donahoo

Theses and Dissertations

This research investigated the individual factors which directly impacted the effectiveness of the 4950th Test Wing local area network (LAN). Areas of interest included the relationships between demographic and user attitude factors and LAN effectiveness. A literature review provided the basis for: 1) operationally defining effectiveness as a subjective measure of user satisfaction; 2) identifying specific factors which impact information system effectiveness; and 3) developing a research instrument to measure user attitudes and user satisfaction. A questionnaire was administered to 342 LAN users 173 were returned (a response rate of 51 percent). Sixteen factors (eight demographic factors and eight attitude …

Networking Your Cd-Roms: A Texas Tale, Margaret Sylvia

Faculty Publications

Installation of a CD-ROM network at St. Mary's University Academic Library created a revolution in the way students and faculty do research.

Intel Nx To Pvm 3.2 Message Passing Conversion Library, Trey Arthur, Michael L. Nelson

Computer Science Faculty Publications

NASA Langley Research Center has developed a library that allows Intel NX message passing codes to be executed under the more popular and widely supported Parallel Virtual Machine (PVM) message passing library. PVM was developed at Oak Ridge National Labs and has become the defacto standard for message passing. This library will allow the many programs that were developed on the Intel iPSC/860 or Intel Paragon in a Single Program Multiple Data (SPMD) design to be ported to the numerous architectures that PVM (version 3.2) supports. Also, the library adds global operations capability to PVM. A familiarity with Intel NX …

A Comparison Of Queueing, Cluster And Distributed Computing Systems, Joseph A. Kaplan, Michael L. Nelson

Computer Science Faculty Publications

Using workstation clusters for distributed computing has become popular with the proliferation of inexpensive, powerful workstations. Workstation clusters offer both a cost effective alternative to batch processing and an easy entry into parallel computing. However, a number of workstations on a network does not constitute a cluster. Cluster management software is necessary to harness the collective computing power. A variety of cluster management and queuing systems are compared: Distributed Queueing Systems (DQS), Condor, Load Leveler, Load Balancer, Load Sharing Facility (LSF - formerly Utopia), Distributed Job Manager (DJM), Computing in Distributed Networked Environments (CODINE), and NQS/Exec. The systems differ in …

Satcom General Purpose Modem Dscs Iii Sct Beacon Telemetry Display, James D. Coppola

Theses and Dissertations

This thesis documents the design and implementation of a DSCS III single Channel Transponder (SCT) beacon telemetry display. The system is a personal computer based design which interfaces to three SCT beacon receiver/demodulators. The software was designed to decode and display both the DSCS III A and DSCS HI B satellite beacons. Recordings of the SCT beacon display can be made on paper and/or magnetic media when triggered by the user, a watchdog timer, or the SCT command accept telemetry bit. In addition, the system can be configured with an IRIG B Universal Time Coordinates (UTC) card which enables the …

Computer Simulation Of A General Purpose Satellite Modem, William L. Montgomery Jr.

Theses and Dissertations

The purpose of this research was to model and simulate the performance of a digital phase shift keyed satellite modem. The probability of bit error (P sub b) at different levels of energy per bit to noise power ratio (E sub b/N sub o) was the performance measure. The channel was assumed to contribute only additive white Gaussian noise. A second order Costas loop performs demodulation in the modem and was the key part of the simulation. The Costas loop with second order Butterworth arm filters was tested by finding the response to a phase or frequency step. The Costas …

An Application Of Neural Networks In Data Communication Real-Time Resource Reallocation, Qing Fan

Electrical & Computer Engineering Theses & Dissertations

This thesis presents an application of artificial neural networks in real-time resource reallocation, a methodology used in the implementation of an intelligent interface node in the Computer Integrated Manufacturing (CIM) environment. In particular, the problem is formulated using a Hopfield neural network model. The real-time reallocation problem is mapped into a two-dimensional matrix of neurons similar to Hopfield and Tank's approach to the traveling salesman problem (TSP) . An energy function is formulated in terms of the hard constraints and the solution cost. The interconnection weights and the input biases are determined by the energy function. It is shown through …

Eies 2 : A Distributed Architecture For Supporting Group Work, Computerized Conferencing & Communications Center, James Whitescarver, Robert M. Czech, Sreenivas Reddy, Ajaz R. Rana, Murray Turoff

Computerized Conferencing and Communications Center Reports

The Computerized Conferencing Center (CCCC) at New Jersey Institute of Technology (NJIT) has been researching on-line group communications for 17 years by developing and studying tools to advance the "collective intelligence". The Electronic Information Exchange System 2 (EIES2) provides a research, development and operational environment for distributed computer supported cooperative work (CSCW) systems. The EIES 2 distributed Smalltalk processor provides for rapid prototyping and implementation of muti-media CSCW facilities in the network environment. The Smalltalk support of the object model, and meta-language properties make it ideally suited for incremental development CSCW applications. The EIES2 communication environment supports a decentralized network …

Visual Speech Training Aid For The Deaf, Subhashri Venkat

Electrical & Computer Engineering Theses & Dissertations

A computer-based vowel articulation training aid has been developed. A "continuous" acoustic-phonetic transformation is performed to map speech parameters to a lower dimensionality display space. There are two possible approaches to this transformation problem. The transformation could be either linear or a combination nonlinear/linear. The nonlinear transformation is performed using a multi-layered feedforward neural network with linear output layers. Speech parameters are extracted either from an analog filter bank arrangement (band energies) or by a digital signal processing procedure (Discrete Cosine Transform Coefficients). The speech parameters obtained from both methods correspond to the spectral envelope of the speech signals. The …

Functional Requirements For Computer Conferencing And Computer Mediated Communications, Computerized Conferencing & Communications Center, Murray Turoff, Starr Roxanne Hiltz, James Whitescarver, John Foster

Computerized Conferencing and Communications Center Reports

This paper is a compilation of the desirable functionality for Computerized Conferencing Systems. It is based upon the research and evaluation activities of the Conferencing Center at NJIT and can he considered as an overall set of objectives for the development of its Conferencing Systems.

Computation Of Frequency Characteristics Of Lumped-Element 3 Db Branch Line Directional Couplers, H. R. Mgombelo

Tanzania Journal of Engineering and Technology (TJET)

An analysis of the 3 dB lumped-element branchline directional coupler constructed using L-C and T networks is given. Matrices of lumped element capacitances and inductances in the form of low and high pass filters are equated to the matrices of the distributed element transmission lines at the centre frequency of operation, as a result of which design equations are derived. Using even and odd modes of excitation, frequency characteristics of the directional couplers are computed and compared to those of the coupler constructed using distributed element transmission lines.

Teaching In A Virtual Classroom : Volume 2 Of A Virtual Classroom On Eies : Final Evaluation Report, Computerized Conferencing & Communications Center, Starr Roxanne Hiltz

Computerized Conferencing and Communications Center Reports

A Virtual Classroom is a teaching and learning environment located within a computer-mediated communication system. As a teaching environment, it provides a set of tools, strengths, and limitations which are available to an instructor for delivering course materials and structuring learning experiences. Its characteristics are merely potentials, just as the empty classroom with its chalkboards and desks awaits the efforts and creativity of the instructor and the students to make it "come alive."

This is the second volume of the final research report on experiences with the prototype of a Virtual Classroom system constructed and operated on EIES, the Electronic …

Learning In A Virtual Classroom : Volume 1 Of A Virtual Classroom On Eies : Final Evaluation Report, Computerized Conferencing & Communications Center, Starr Roxanne Hiltz

Computerized Conferencing and Communications Center Reports

The Virtual Classroom [TM] is a system for learning and communicating via connected computers. Students in the Virtual Classroom share their thoughts, questions and reactions with professors and classmates using computers equipped with specially designed software. The software enables students to send and receive messages, interact with professors and classmates, read and comment on lecture material, take tests and receive feedback, and more, without having to attend scheduled classes. Learning can take place at any location in the world and at any time of the day using a computer on campus, at home or in the workplace.

The primary goal …

Compiling Unit Clauses For The Warren Abstract Machine, George D. Herbert

UNF Graduate Theses and Dissertations

This thesis describes the design, development, and installation of a computer program which compiles unit clauses generated in a Prolog-based environment at Argonne National Laboratories into Warren Abstract Machine (WAM) code. The program enhances the capabilities of the environment by providing rapid unification and subsumption tests for the very significant class of unit clauses. This should improve performance substantially for large programs that generate and use many unit clauses.

The Virtual Classroom: Building The Foundations, Computerized Conferencing & Communications Center, Starr Roxanne Hiltz

Computerized Conferencing and Communications Center Reports

This is a report on the first year of a three-year project concerned with the development and assessment of new types of software capabilities designed to support university level courses. A "virtual classroom" or "university without walls" is being created within a computerized conferencing system. During the first year of the project, students in twelve courses at three universities completed part or all of their coursework online. Pre and post-course questionnaires and automatic monitoring of their computer-mediated communications are the main sources of data. Independent variables include the expectations and attributes of the individual students; characteristics of the particular hardware …

Deterministic Linear Predictors For Bit Rate Improvement, Dhanvant H. Goradia

Electrical & Computer Engineering Theses & Dissertations

This thesis addresses the application of deterministic linear predictor s for telemetry based systems. Deterministic linear predictors are considered as a viable alternative to block transform coding in order to achieve bit rate reduction. A method of calculating the predictor coefficients of a deterministic linear predictor is presented. The system model is developed parametrically with respect to the bandwidth, polynomial order, signal class and predictor length. Two classes of signals, deterministic and random are analyzed and bounds on the performance of the deterministic linear predictor are established. A family of six pole Butterworth filters are used as presample filters in …

Moderating Online Conferences, Revised Manuscript, Computerized Conferencing & Communications Center, Elaine B. Kerr

Computerized Conferencing and Communications Center Reports

While considerable lore has accumulated about effective leadership techniques for groups interacting electronically, until now it has not been systematically presented. This material is culled from the experiences of those who have moderated past online conferences, the knowledge common to the EIES User Consultants, and observed behavior from thousands of conferences convened on EIES in the past. While this is a system-specific guide, the general principles ought to be generalizable to other systems, with different structures for group discussion.

Robert Burns put it well:
The best laid schemes o' mice and men
Gang aft a-gley;
An' lea'e us nought but …

Integrating Working At Home With Information Systems Management, Computerized Conferencing & Communications Center, Joseph C. Schuh

Computerized Conferencing and Communications Center Reports

The history of computerization has its origin in the automation of manual processes - searching out the segments that could be put on a computer. The intended result was that the entire job would be done faster and cheaper. Thus, current computer-based information systems tend to make more efficient use of computers than people. The management function, on the other hand, often seems to focus on competitive skills and salesmanship rather than on the ability to attract and hold talented people. But, such impersonal factors that have driven management practices are changing. There has been a complete reversal in the …

An Investigation To Improve Linear Predictive Vocoder Pulse/Noise Excitation Models, Elizabeth Annella Martina Effer

Electrical & Computer Engineering Theses & Dissertations

The quality of synthetic speech from Linear Predictive (LP) vocoders is known to be degraded due to the lack of detail in the commonly used pulse/noise excitation model. In this investigation, it was hypothesized that this degradation is due to the lack of precise timing information in the pulses and to the constraint that each short-time segment of excitation be either an impulse train or white noise. Accordingly, more complex excitation models were implemented using precise timing from peaks in the residual and a mixture of pulses and noise. Since the LP residual is known to be the perfect excitation …

Determinants Of Acceptance Of Computer Mediated Communication System, Computerized Conferencing & Communications Center, Starr Roxanne Hiltz, Elaine B. Kerr, Kenneth Johnson, Murray Turoff

Computerized Conferencing and Communications Center Reports

Acceptance of Computer-Mediated communication Systems (CMCS) by managers and professionals corresponds to its incorporation into their daily patterns of communication and work. Acceptance includes at least three inter-related dimensions: amount of use, subjective satisfaction with the process of using the system, and a perception that system use has positive impacts upon productivity.

Pre-use and follow-up questionnaires were distributed to 150- 250 new users of four different CMCS. Three are conferencing systems, designed to support "group work." They differ in terms of comprehensiveness or complexity of design, and size and nature of the user communities; COM/KOM, a Swedish system with mostly …

An Inventory Of Maine's Telecommunications System, Maine State Planning Office

Maine Collection

An Inventory of Maine's Telecommunications System

Prepared for the Maine State Planning Office by Joseph M. Chaisson and Valerie Lamont of the Telecommunications Research Program at Westbrook College in Portland, Maine. July, 1985.

"The Primary purpose of this report is to provide information for Governor Brennan's Task Force on Telecommunications. The inventory also can be widely used as a reference by persons and organizations concerned with providing telecommunications services in Maine."

Contents: Introduction / Local Telephone Service / Mobile Telephone Service / Digital Termination Service / Cable Television / Paging Systems / Intra-State (Intra-LATA) Public Services / Intra-State (Intra-LATA) Private …

Mode Of Communication And The "Risky Shift" : A Controlled Experiment With Computerized Conferencing And Anonymity In A Large Corporation, Computerized Conferencing & Communications Center, Starr Roxanne Hiltz, Murray Turoff, Kenneth Johnson

Computerized Conferencing and Communications Center Reports

Peer groups of five managers in a large company with a well developed corporate culture engaged in choice dilemma tasks using three modes of communication: face-to-face, synchronous computerized conferences with regular names, and synchronous computerized conferences with assigned pen names. This is the final technical report on the experiment, including documentation of all procedures, and reports of the tests of all hypotheses, including those which were not supported.

Choice behavior varied by problem and mode of communication. On a problem related to a major decision on the future of the company, conservative choices and conservative shifts dominated. On two choice …