Engineering Commons^™

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.

Observation Of A New Charmed Strange Meson, Kubota, Y.; Et Al., M. Thulasidas

Research Collection School Of Computing and Information Systems

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 …

Immittance Spectroscopy Of Smart Components And Novel Devices, Mohammad Anwarul Alim, Sanjida Khanam, Martin A. Seitz

Electrical and Computer Engineering Faculty Research and Publications

AC small-signal immittance spectroscopy is employed as a viable tool to demonstrate electrical characterization, performance improvement, and quality assurance issues of smart materials-based components and novel devices. The variation in the ac response, complemented via dc measurements within a range of tolerating temperature, delineates competing phenomena occurring in the microstructures of these engineering material systems. The results are presented in a generic manner with possible explanations on the mechanisms for two selected Debye-like (nearly ideal) and non-Debye (non-ideal) low-capacitance resistors. This spectroscopic approach allows systematic development of a representative equivalent circuit, considered to be the characteristic of the devices and …

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.

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.

Script-Based Qos Specifications For Multimedia Presentations, Richard Staehli, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Multimedia presentations can convey information not only by the sequence of events but by their timing. The correctness of such presentations thus depends on the timing of events as well as their sequence and content. This paper introduces a formal specification language for playback of real-time presentations. The main contribution of this language is a quality of service (QOS) specification that relaxes resolution and synchronization requirements for playback. Our definitions give a precise meaning to the correctness of a presentation. This specification language will form the basis for a QOS interface for reservation of operating system resources.

Partitioning Structural Vhdl Circuits For Parallel Execution On Hypercubes, Kevin L. Kapp

Theses and Dissertations

Distributing simulations among multiple processors is one approach to reducing VHDL simulation time for large VLSI circuit designs. However, parallel simulation introduces the problem of how to partition the logic gates and system behaviors among the available processors in order to obtain maximum speedup. This research investigates deliberate partitioning algorithms that account for the complex inter-dependency structure of the circuit behaviors. Once an initial partition has been obtained, a border annealing algorithm is used to iteratively improve the partition. In addition, methods of measuring the cost of a partition and relating it to the resulting simulation performance are investigated. Structural …

An Object-Oriented Database Interface For Ada, Anthony D. Moyers

Theses and Dissertations

Object data management ODM is currently at the forefront of research and development efforts in the database community. In order to take advantage of ODM technology, the Department of Defense DoD needs to ensure that these systems are accessible to Ada programmers. The Air Force Institute of Technology AFIT is conducting research towards the development of an Ada ODM interface to existing ODM systems. The design goals are portability, transparency, and completeness for Ada programmers. Portability means that the ODM system can be changed without affecting any existing application programs. Transparency means that Ada programmers can use the interface without …

Virtual Memory Management And Virtual Bus Overloading On Multiple Channel Architectures, John N. Armitstead

Theses and Dissertations

Today's computational environment requires the processing capabilities available only through parallel architectures. The bottleneck that limits the potential of parallel processing is communication between processors, memories, and other hardware devices. A proposed multiple channel architecture (MCA) utilizes tunable semiconductor lasers and fiber optic cables that serve as the communication medium between processor, memory, and I/O nodes. A memory management unit (MMU) was completely described and implemented in a multiprocessor simulator. A permutation-based interleaving (PBI) scheme was utilized to reduce the chance of memory access collisions. Virtual bus utilization, number of collisions, and message traffic patterns were studied under various amounts …

Interactive Control Of A Parallel Simulation From A Remote Graphics Workstation, Douglas C. Looney

Theses and Dissertations

Modern military commanders are faced with an overwhelming amount of intelligence data concerning the disposition of engaging forces, The sheer volume of data produced for a single planning scenario is an obstacle to the user as well as the computer. Today’s commander requires a real-time, three- dimensional representation of the battlefield in order to assimilate the data for the management of a conflict. Parallel computation is required to complete the processing of this information in a timely manner. A network protocol is required to link the interface with the parallel simulation. The of this study is to improve user interaction …

Genetic Algorithms Applied To A Mission Routing Problem, James B. Olsan

Theses and Dissertations

This thesis applies genetic algorithms to a mission routing problem. The mission routing problem involves determining an aircraft’s best route between a staging base and a target. The goal is to minimize the route distance and the exposure to radar. Potential routes are mapped to a 3-dimensional mesh where the nodes correspond to checkpoints in the route and the arcs correspond to partial paths of the route. Each arc is weighted with respect to distance and exposure to radar. A genetic algorithm is a probabilistic search technique loosely based on theories of biological evolution. Genetic crossover and survival of the …

Design Of A Parallel Discrete Event Simulation Coprocessor, Jacob L. Berlin

Theses and Dissertations

A Parallel Discrete Event Simulation Coprocessor was designed to off- load the synchronization overhead from the processors executing the application. In a multiprocessor architecture, one coprocessor executes the synchronization routines for each host processor. Speedup can be achieved when the host processor executes the application and the coprocessor concurrently executes synchronization routines. The coprocessor uses a programmable microcode control store to guarantee flexibility in the synchronization routines. The coprocessor uses an Extreme Search Associative Memory to support fast Next Event Queue NEQ management. This associative memory uses bit-serial word-parallel search logic to provide 01 insert and retrieval time of events …

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 …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 9, Number 10, December 1993, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

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

Using Discovery-Based Learning To Prove The Behavior Of An Autonomous Agent, David N. Mezera

Theses and Dissertations

Computer-generated autonomous agents in simulation often behave predictably and unrealistically. These characteristics make them easy to spot and exploit by human participants in the simulation, when we would prefer the behavior of the agent to be indistinguishable from human behavior. An improvement in behavior might be possible by enlarging the library of responses, giving the agent a richer assortment of tactics to employ during a combat scenario. Machine learning offers an exciting alternative to constructing additional responses by hand by instead allowing the system to improve its own performance with experience. This thesis presents NOSTRUM, a discovery-based learning DBL system …

A Method For Populating The Knowledge Base Of Aptas, A Domain-Oriented Application Composition System, Raleigh A. Sandy Iii

Theses and Dissertations

A formal process is described for populating the knowledge base of the Automatic Programming Technologies for Avionics Software APTAS system. This process was developed using a general knowledge base population process that applies to many knowledge-based software engineering systems. This general process is also described. The formal process for APTAS was demonstrated by storing new information from the radar tracking domain into the knowledge base of APTAS. Several procedures some automatic and some manual were implemented to support the formal process.

Simple High-Quality Lossy Image Coding Scheme, Shaolin Bi, Khalid Sayood

Department of Electrical and Computer Engineering: Faculty Publications

A simple yet efficient image data compression method is presented. This method is based on coding only those segments of the image that are perceptually significant to the reconstruction of the image. Sequences of image pixels whose gray-level differences from the pixels of the previous row exceed two prespecified thresholds are considered significant. These pixels are coded using a differential pulse code modulation scheme that uses a 15-level recursively indexed nonuniform quantizer for the first pixel in a segment and a 7-level recursively indexed nonuniform quantizer for all other pixels in the segment. The quantizer outputs are Huffman coded. Simulation …

Investigation Of Solution Space Of Trees And Dags For Realization Of Combinational Logic In At 6000 Series Fpgas, Philip Ho

Dissertations and Theses

Various tree and Directed Acyclic Graph structures have been used for representation and manipulation of switching functions. Among these structures the Binary Decision Diagrams have been the most widely used in logic synthesis. A BDD is a binary tree graph that represents the recursive execution of Shannon's expansion. A FDD is a directed function graph that represents the recursive execution of Reed Muller expansion.

A family of decision diagrams for representation of Boolean function is introduced in this thesis. This family of Kronecker Functional Decision Diagrams (KFDD) includes the Binary Decision Diagrams (BDD) and Functional Decision Diagrams (FDD) as subsets. …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 9, Number 9, November 1993, 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 9, Number 8, October 1993, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

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

Declarative Representations Of Multiagent Systems, Munindar P. Singh, Michael N. Huhns, Larry M. Stevens

Faculty Publications

This paper explores the specification and semantics of multiagent problem-solving systems, focusing on the representations that agents have of each other. It provides a declarative representation for such systems. Several procedural solutions to a well-known test-bed problem are considered, and the requirements they impose on different agents are identified. A study of these requirements yields a representational scheme based on temporal logic for specifying the acting, perceiving, communicating, and reasoning abilities of computational agents. A formal semantics is provided for this scheme. The resulting representation is highly declarative, and useful for describing systems of agents solving problems reactively.

Cyclo-Static Scheduling Of Large Grain Dataflow Algorithms On A Local Area Atamm Multicomputing Testbed, Sudeepto Roy

Electrical & Computer Engineering Theses & Dissertations

A strategy for cyclo-statically scheduling deterministic large grain dataflow (LGDF) algorithms for distributed execution on loosely coupled multicomputer architectures is presented in this research. The computational paradigm used is the ODU/NASA developed Algorithm To Architecture Mapping Model (ATAMM), which consists of marked graphs and Gantt chart representations that model the iterative execution of deterministic LGDF algorithms for different values of throughput and computation time. It is postulated that the behavior of these algorithms could be represented by the aggregate execution of an ensemble of cyclically shifted threads of a specific node sequence. Assuming the existence of one or more such …

Acoustic Correlates Of Vowel Perception As Determined From Synthesis Experiments With Multi-Tone Stimuli, Zhongjiang Zhang

Electrical & Computer Engineering Theses & Dissertations

An essential requirement of speech signal processing is to extract information (features or parameters) from the speech signal which encode the information carried by the signal. The objective of this thesis work was to examine and evaluate two feature sets as acoustic correlates for vowel perception. They are formants and DCTCs. Formants are the frequencies of spectral peaks of the speech signal. DCTCs are the Discrete Cosine Transform Coefficients of the magnitude spectrum and are thus features which encode the global spectral shape of speech signal.

There are different opinions regarding which feature set is a more accurate representation for …

Gyroless Line-Of-Sight Stabilization For Pointing And Tracking Systems, Marcelo C. Aigrain

Department of Electrical and Computer Engineering: Faculty Publications

A new platform stabilization approach is described where miature, low-cost, linear accelerometers are used (instead of gyroscopes) for line-of-sight (LOS) stabilization. This is accomplished by placing the accelerometers at strategic locations and combining their outputs so that angular motion is determined from linear acceleration measurements. The control system uses the sensed angular accelerations to generate movement commands for the gimbal servomotors in the stabilization platform. This counterrotates the imaging device to stabilize its LOS. The use of accelerometers allows the servo system to operate in an acceleration control mode, which is more desirable than position or velocity control modes, typical …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 9, Number 7, September 1993, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

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

Electronic Simulation Of The Temporal Characteristics Of Photon Memory Echoes And Some Related Applications, Yuwen Kuo, Monish Ranjan Chatterjee

Electrical and Computer Engineering Faculty Publications

The characteristics of nonlinear photon memory echoes are investigated by means of SPICE simulations using equivalent resonator ensembles. By developing implicit nonlinear circuit models in the memory echo domain, the triple product formalism of electronic holography, involving correlation and convolution, is tested for the storage and recall of arbitrary signals and/or data bit streams in both time-inverted and nontime-inverted modes. Furthermore, a few specific optical data processing applications are also simulated in which the mixed binary multiplication of two or more binary bit streams is achieved.

Higher order products, optical pattern recognition, and other possible applications are also discussed. It …