Digital Commons Network^™

Evaluation Of An Acoustic Charge Transport (Act) Device For Adaptive Interference Suppression In Spread Spectrum Communications Systems, Michael S. Mills

Theses and Dissertations

Analytical results have shown that adaptive filtering can be a powerful tool for the rejection of narrowband interference in a direct sequence spread spectrum receiver. However, the complexity of adaptive filtering hardware has hindered the experimental validation of these results. This thesis describes a unique adaptive filter architecture for implementing the Widrow-Hoff Least- Mean-Square (LMS) algorithm using two state-of-the-art Acoustic Charge Transport (ACT) Programmable Transversal Filters (PTFs). Signal-to-noise ratio improvement measurements demonstrate the effectiveness of the adaptive filter for suppressing single- and dual-tone jammers at jammer-to-signal ratios (JSRs) of up to 30 dB. It is shown that the ACT adaptive …

The Afit Multielectrode Array For Neural Recording And Simulation: Design, Testing, And Encapsulation, James R. Reid Jr

Theses and Dissertations

A two-dimensional, X-Y addressable, multiplexed array of 256 electrodes (16 x 16) has been fabricated using conventional semiconductor processing techniques. The individual electrodes are 16O microns x 160 microns, approximating the size of the cortical columns; the overall array size is 3910 microns x 3910 microns. The array has been fitted to a chronically implantable package and tested for several days in a simulated neural environment. EEG-like data were collected successfully from individual electrodes in the array. This array improves on a previous design of a 16 electrode (4 x 4) array that was chronically implanted on the cortex of …

An Analysis Of The Root Causes Of Delays And Deficiencies In The Development Of Embedded Software For Air Force Weapon Systems, Jay R. Hopkins, Curtis De Keyrel

Theses and Dissertations

The importance of embedded software, used in every subsystem of ah major weapon systems used by the United States Air Force, has increased drastically over the last decades. However, in spite of the regulations currently in existence, developing and acquiring software which meets the user requirements within the original cost and schedule estimates continues to be difficult. At the same time, the Air Force has pushed to improve the development process with the Total Quality Management TQM program. The primary method used to improve the process has been to create metrics, collect data on these metrics, and then perform a …

The Development And Use Of An Evaluation Mechanism For The Assessment Of Software Configuration Management Tools, Wayne M. Descheneau, Neil W. Robinson

Theses and Dissertations

This study investigated the development of a mechanism for use in the evaluation of Software Configuration Management SCM tools. An examination of applicable DoD standards identified the SCM requirements that could be levied on a development contractor, and a literature search revealed the functionality common to various automated tools. These two sets of information were organized into a matrix, and for each requirement that was met, the intersection on the matrix of the requirement and each functionality used to meet that requirement was checked. In addition to the matrix, the mechanism consisted of general information about a given tool and …

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.

Genetic Algorithms For Soft Decision Decoding Of Linear Block Codes, Harpal Maini, Kishan Mehrotra, Chilukuri K. Mohan, Sanjay Ranka

Electrical Engineering and Computer Science - Technical Reports

Soft-decision decoding is an NP-hard problem of great interest to developers of communication systems. We show that this problem is equivalent to the problem of optimizing Walsh polynomials. We present genetic algorithms for soft-decision decoding of binary linear block codes and compare the performance with various other decoding algorithms. Simulation results show that our algorithms achieve bit-error-probabilities as low as 0.00183 for a [104, 52] code with a low signal-to-noise ratio of 2.5 dB, exploring only 30,000 codewords, whereas the search space contains 4.5 x 1015 codewords. We define a new crossover operator that exploits domain-specific information and compare it …

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.

Asynchronous Parallel Schemes: A Survey, Eric Jui-Lin Lu, Michael Gene Hilgers, Bruce M. Mcmillin

Computer Science Technical Reports

It is well known that synchronization and communication delays are the major sources of performance degradation of synchronous parallel algorithms. It has been shown that asynchronous implementations have the potential to reduce the overhead to minimum. This paper surveys the existing asynchronous schemes and the sufficient conditions for the convergence of the surveyed schemes. Some comparisons among these schemes are also presented.

Project Isaac: Building Simulations For Virtual Environments, George Vanĕček, James Cremer

Department of Computer Science Technical Reports

No abstract provided.

Dealing With Mobility: Issues And Research Challenges, Evaggelia Pitoura, Bharat Bhargava

Department of Computer Science Technical Reports

No abstract provided.

The Design And Implementation Of Tripwire: A File System Integrity Checker, Gene H. Kim, Eugene H. Spafford

Department of Computer Science Technical Reports

No abstract provided.

An Adaptive Coding Scheme With Code Combining For Mobile Radio Systems, Robert H. Deng, Huafei Zhou

Research Collection School Of Computing and Information Systems

The authors propose and study an adaptive error-control coding scheme for binary digital FM (BFM) mobile radio transmission. The scheme employs code combining through packet retransmissions. The number of transmissions of a packet is in proportion to the channel fading/noise levels, which is in contrast to time diversity techniques where a fixed number of repetitions of a data packet is performed even in the absence of channel errors. Furthermore, the receiver uses received signal envelopes as channel state information, which significantly improves the throughput and bit error rate (BER) performance. Performance of the proposed scheme is analyzed for frequency-flat Rayleigh …

Object-Oriented Design And Implementation Of A Parallel Ada Simulation System, James T. Belford

Theses and Dissertations

Simulations which model the behavior real world entities are often large and complex, and require frequent changes to the configuration. This research effort examines the benefits of using object-oriented techniques to develop a distributed simulation environment which supports modularity, modifiability, and portability. The components of the Parallel Discrete Event Simulation PDES environment are identified and modeled using the Rumbaugh modeling technique. From the model, a prototype implementation of a Parallel Ada Simulation Environment PASE is accomplished using Classic Ada. A system interface for the Intel ipsc2 Hypercube was developed to illustrate the concepts of modularity and portability. In addition, the …

Methodology For Modeling High Performance Distributed And Parallel Systems, Rakesh Kushwaha

Dissertations

Performance modeling of distributed and parallel systems is of considerable importance to the high performance computing community. To achieve high performance, proper task or process assignment and data or file allocation among processing sites is essential. This dissertation describes an elegant approach to model distributed and parallel systems, which combines the optimal static solutions for data allocation with dynamic policies for task assignment. A performance-efficient system model is developed using analytical tools and techniques.

The system model is accomplished in three steps. First, the basic client-server model which allows only data transfer is evaluated. A prediction and evaluation method is …

A Comprehensive Part Model And Graphical Schema Representation For Object-Oriented Databases, Michael H. Halper

Dissertations

Part-whole modeling plays an important role in the development of database schemata in data-intensive application domains such as manufacturing, design, computer graphics. text document processing, and so on. Object-oriented databases (OODBs) have been targeted for use in such areas. Thus, it is essential that OODBs incorporate a part relationship as one of their modeling primitives. In this dissertation, we present a comprehensive OODB part model which expands the boundaries of OODB part-whole modeling along three fronts. First, it identifies and codifies new semantics for the OODB part relationship. Second, it provides two novel realizations for part relationships and their associated …

Morphological Operations In Image Processing And Analysis, Chamim Christopher Pu

Dissertations

Morphological operations applied in image processing and analysis are becoming increasingly important in today's technology. Morphological operations which are based on set theory, can extract object features by suitable shape (structuring elements). Morphological filters are combinations of morphological operations that transform an image into a quantitative description of its geometrical structure which based on structuring elements. Important applications of morphological operations are shape description, shape recognition, nonlinear filtering, industrial parts inspection, and medical image processing.

In this dissertation, basic morphological operations are reviewed, algorithms and theorems are presented for solving problems in distance transformation, skeletonization, recognition, and nonlinear filtering. A …

Medium Access Control Mechanisms For High Speed Metropolitan Area Networks, Michail Papamichail

Dissertations

In this dissertation novel Medium Access Control mechanisms for High Speed Metropolitan Area networks are proposed and their performance is investigated under the presence of single and multiple priority classes of traffic. The proposed mechanisms are based on the Distributed Queue Dual Bus network, which has been adopted by the IEEE standardization committee as the 802.6 standard for Metropolitan Area Networks, and address most of its performance limitations. First, the Rotating Slot Generator scheme is introduced which uses the looped bus architecture that has been proposed for the 802.6 network. According to this scheme the responsibility for generating slots moves …

Using Temporal Subsumption For Developing Efficient Error-Detecting Distributed Algorithms, Martina Schollmeyer, Bruce M. Mcmillin

Computer Science Technical Reports

Distributed algorithms can use executable assertions derived from program verification to detect errors at run-time. However, a complete verification proof outline contains a large number of assertions, and embedding all of them into the program to be checked at run-time would make error-detection very inefficient.

The technique of temporal subsumption examines the dependencies between the individual assertions along program execution paths. In contrast to classical subsumption, where all logical expressions to be examined are true simultaneously, an assertion need only be true when the corresponding statement in the distributed program has been executed. Thus, temporal subsumption based on the set …

A Run-Time Decision Procedure For Responsive Computing Systems, Grace Tsai, Matt Insall, Bruce M. Mcmillin

Computer Science Technical Reports

A responsive computing system is a hybrid of real-time, distributed and fault-tolerant systems. In such a system, severe consequences will occur if the logical and physical specifications of the system are not met. In this paper, we present a logic, Interval Temporal Logic (ITL), to specify responsive systems and give decision procedures to verify properties of the system at run-time as follows. First, we collect, during execution, events occurring in the system to represent a distributed computation. Next, we specify properties of the system using ITL formulas. Finally, we apply the decision procedures to determine satisfaction of the formulas. Thus, …

Establishing A Distributed Processing And Distributed Database Environment For Intergraph Mge & Orscle Products, Praveen Chandrasekhar

Electronic Dissertations and Theses

The department of Agricultural Economics undertake various government contracts for GIS based applications. Currently, they have multi-year contracts with the Louisiana Department of Health and Hospitals (LDHH). This contract is carried out in the Agricultural Economics Geographical Information System lab (AEGIS). One part of the contract is to integrate a heterogenous system comprising of PCs and Intergraph workstations so that the PC can share the data or Microstation Geographical information system Environment (MGE) and ORACLE based applications. Since the Department also undertakes other contracts which requires them to use ARC/INFOR as the front-end while the data would reside in ORACLE …

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.

Semantics-Based Information Brokering: A Step Towards Realizing The Infocosm, Vipul Kashyap, Amit P. Sheth

Kno.e.sis Publications

The rapid advances in computer and communication technologies, and their merger, is leading to a global information market place. It will consist of federations of very large number of information systems that will cooperate to varying extents to support the users' information needs. We propose an architecture which may facilitate meeting these needs. It consists of three main components: information providers, information brokers and information consumers. We also propose an approach to information brokering. We discuss two of it's tasks: information resource discovery, which identities relevant information sources for a given query, and query processing, which involves the generation of …

Mobile-Process Based Distributed Memory Simulations, Janche Sang, Edward Mascarenhas, Vernon J. Rego

Department of Computer Science Technical Reports

No abstract provided.

Scheduling With Compensation In Multi- Database Systems, Aidong Zhang, Bharat Bhargava

Department of Computer Science Technical Reports

No abstract provided.

Efficient Implementation Of Thread Migration On Distributed-Memory Multi-Processors, Janche Sang, Vernon J. Rego

Department of Computer Science Technical Reports

No abstract provided.

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 …

Structured And Object-Oriented Methodologies: A Comparative Analysis Based On A Case Study, Gary Brian Warren

Honors Capstone Projects and Theses

No abstract provided.

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.

Rsvp: A New Resource Reservation Protocol, Daniel Zappala, Stephen Deering, Deborah Estrin, Scott Shenker, Lixia Zhang

Faculty Publications

The current Internet architecture, embodied in the Internet Protocol (IP) network protocol, offers a very simple service model: point-to-point best-effort service. In recent years, several new classes of distributed applications have been developed, such as remote video, multimedia conferencing, data fusion, visualization, and virtual reality. It is becoming increasingly clear that the Internet’s primitive service model is inadequate for these new applications. This inadequacy stems from the failure of the point-to-point best-effort service model to address two application requirements. First, many of these applications are very sensitive to the quality of service their packets receive. For a network to deliver …

Modeling Flexibility In Distributed Transactions, Ahmed Elmagarmid, Aidong Zhang

Department of Computer Science Technical Reports

No abstract provided.