Computer Engineering Commons^™

A Formal Object Model For Layered Networks To Support Verification And Simulation, Rasha M. B. E. Morsi

Electrical & Computer Engineering Theses & Dissertations

This work presents an abstract formal model of the interconnection structure of the Open Systems Interconnection Reference Model (OSI-RM) developed using Object-Oriented modeling principles permitting it to serve as a re-usable platform in supporting the development of simulations and formal methods applied to layered network protocols. A simulation of the object model using MODSIM III was developed and Prototype Verification System (PVS) was used to show the applicability of the object model to formal methods by formally specifying and verifying a Global Systems for Mobile communications (GSM) protocol. This application has proved to be successful in two aspects. The first …

Minimum Mean Square Error Spectral Peak Envelope Estimation For Automatic Vowel Classification, Jaishree Venugopal

Electrical & Computer Engineering Theses & Dissertations

Spectral feature computations continue to be a very difficult problem for accurate machine recognition of speech. In this work, which focuses on vowels, a new spectral peak envelope method for vowel classification is developed, based on a missing frequency components model of speech recognition. According to the missing frequency components model, vowel recognition depends only on the spectral (harmonic) peaks. Smoothing and interpolation of the spectra, performed in the standard cepstral analysis method commonly used in automatic speech recognition, actually loses valuable information and results in reduced recognition accuracy. The new method for feature extraction presented in this thesis is …

Studies Related To The Design And Implementation Of A Magnetic Suspension And Balance System, Syed Adeel Akhtar Jafri

Electrical & Computer Engineering Theses & Dissertations

This thesis presents studies related to the magnetic suspension and balance system (MSBS) of the Princeton/ONR High Reynolds Number Testing Facility (HRTF). The main motivation for developing the MSBS is to provide interference free aero/hydrodynamic testing of submersible models, which will lead to more accurate measurements. From the controls point of view, the main specification of the MSBS is to robustly control the position of a submersible model in five degrees of freedom (DOF), including three translational as well as pitching and yawing positions. The MSBS should not only regulate the submersible model's position but should also allow for small …

A Flowchart Structure For Modification Of A Modsim Process Model, Murali K. Adatrao

Electrical & Computer Engineering Theses & Dissertations

There are many software processes and software development models that support the development of a software model prior to implementation. However, more often than not, these practices are not followed resulting in a lack of documentation of the intended functionality of the software. As a result, software often becomes a black box for later developers. Even a simple bug fix can turn into an exhaustive task for the developers, as they must attempt to infer the intended system behavior. New designers cannot make any changes to the software or extend the software behavior, as the underlying model within the software …

Process Flow Optimization Studies Through Discrete Event Simulation, Milind Chokshi

Electrical & Computer Engineering Theses & Dissertations

Computer-aided simulation has begun to emerge as a powerful tool for numerical analysis of the behavior and anticipated performance of industrial systems and their optimization. Applications include materials handling, storage and controls systems, prediction of manufacturing efficiencies, and production optimization. Simulations are used to test baseline models and subsequently analyze new production concepts, operating strategies, and planned procedures prior to costly implementation.

The study of process flows in a manufacturing environment is difficult due to its inherent stochastic nature. Breakdown of the sub-systems and failures of machines is a random process and needs to be solved based on concepts of …

A Generic Object-Oriented Server Model, Brian Douglas Jones

Electrical & Computer Engineering Theses & Dissertations

The purpose of this paper is to introduce a generic, object-oriented model for the simulation of networks of queues. Generic simulation modeling provides robust ways of laying out processes in stochastic, event driven simulations. The approach taken is to define a methodology that will be implementation independent, termed the Generic Server Simulation Model (GSSM); thus, leaving the implementers to choose the best (most suited for their use) means of implementation. GSSM uses many object-oriented concepts to provide its basic structure and has in its design the ability to take advantage of these object-oriented concepts, including reuse of (existing) code. GSSM …

A Digital Pressure Sensor Data Acquisition System In A Wind Tunnel Model, John J. Novakoski

Electrical & Computer Engineering Theses & Dissertations

Pressure measurements on wind tunnel models provide an important aid to overall aerodynamic analysis and design of aircraft and vehicles. Most pressure measurements in wind tunnels are made using analog pressure sensors with interfacing electronics that connect to an external data acquisition unit. Some of desirable features of an improved pressure measurement system are that it be: 1) model embeddable, 2) inherently digital in nature, 3) intelligent, and 4) controllable by a remote computer.

An intelligent, model-embedded, eight-channel digital pressure sensor system has been developed and tested in a wind tunnel. The implemented system consists of Micro-Electro-Mechanical System (MEMS) digital …

Dynamic And Interactive 3d Simulation Over The World Wide Web, Rajesh Vennam

Electrical & Computer Engineering Theses & Dissertations

The thesis presents the development of a new and novel three-dimensional simulation tool over the WWW using Virtual Reality Modeling Language (VRML). VRML is a 3D analog to HTML and serves as a simple, multiplatform language for publishing 3D Web pages. In general, most people use VRML for developing three-dimensional models or worlds that provide little or no interaction for the users. This tool combines interaction and dynamic object creation. A thorough study of VRML is done to explore the features of VRML that could be combined to develop methodologies for creation of dynamic and interactive 3D objects over the …

Variability Analysis Of Discrete Cosine Transform Coefficient (Dctc) Features For Speech Processing, Bingjun Dai

Electrical & Computer Engineering Theses & Dissertations

In this research, the variability of Discrete Cosine Transform Coefficient (DCTC) features was investigated. Additionally, a new pitch-synchronous processing method was explored to increase the stability of features and to reduce window effects when compared to the regular method. The noise sources that lead to feature variability were analyzed, and different smoothing methods were tested. It was found that longer frames, frequency warping, time smoothing of the log spectrum, and DCS level time smoothing, all help reduce DCTC variability and increase classification performance. The pitch­ synchronous method was implemented with Matlab. Important processing methods, including pitch period estimation, time­ domain …

The Cluster Multipole Algorithm For Far-Field Computations, Rakesh R. Patel

Electrical & Computer Engineering Theses & Dissertations

Computer simulations of N-body systems are beneficial to study the overall behavior of a number of physical systems in fields such as astrophysics, molecular dynamics, and computational fluid dynamics. A new approach for computer simulations of N-body systems is proposed in this research. The new algorithm is called the Cluster Multipole Algorithm (CMA). The goals of the new algorithm are to improve the applicability to non-point sources and to provide more control on the accuracy over current algorithms. The algorithm is targeted to applications that do not require rebuilding the data structure about the system every time step due to …

Spectral/Temporal Segment Features For Automatic Speech Recognition, Xi Hong Wang

Electrical & Computer Engineering Theses & Dissertations

In this thesis an approach for efficiently computing a compact spectral/temporal feature set for representing a segment of speech, with effective resolution depending on both frequency and time position within the segment, is developed, analyzed, and tested. The goal of this method is to mimic the resolution properties of the human auditory system, but using a computationally efficient FFT-based front end rather than a more complex auditory model. In particular this method applies both frequency and time "warping" to FFT spectra to obtain good frequency resolution at low frequencies and good time resolution at high frequencies. Time resolution is also …

Formal Specification Of Fragmentation And Reassembly In Ipv6, Ibrahim Sahin

Electrical & Computer Engineering Theses & Dissertations

Development and implementation of a networking standard such as the new Internet Protocol (IPv6) is a very difficult process. Different implementations of the standard must be fully compatible to allow different computers to communicate with each other. However, standards are often ambiguous, frequently a result of providing specifications in the English language. A more formal specification could assist in the design of systems. This thesis demonstrates that capability using the Prototype Verification System (PVS).

In this thesis study, a formal specification for fragmentation and reassembly in IPv6 was created to provide a tool for the standardization of IPv6 using PVS. …

Specification And Verification Of Generic Cell Rate Algorithms In Pvs, Huseyin Ozgungor

Electrical & Computer Engineering Theses & Dissertations

Formal verification methods have been considered as a powerful complementary approach to define standards and to prove correctness of the systems. In this work, formal specification of Generic Cell Rate Algorithms are defined and proved. The specification process enables standardization for constructing Generic Cell Rate Algorithms. Standardization is an important process in the Asynchronous Transfer Mode (ATM) networks. By employing formal methods, the necessary standards could be constructed to allow different algorithms to be employed which still meet system requirements. Those system requirements are quantified in the Quality of Service (QOS).

Congestion management is a vital concept for networks in …

Real-Time Visual Speech Articulation Training Aid, Neiyer S. Correal

Electrical & Computer Engineering Theses & Dissertations

A real-time visual articulation training aid has been implemented. It provides instantaneous visual feedback of vowel and stop-consonant production on a computer screen. The vowel training system corresponds to an improved floating-point implementation of a previous fixed-point system developed by Beck (1992). The new implementation provides better accuracy and an approximate five-fold increase in speed. Acoustic features computed from global short-time spectral shape are used for classification of vowels. Temporal spectral trajectories timed to begin with burst onset are used for stop consonants. A neural network is used to transform measurements of auditory stimuli from the feature space to a …

Resource/Dataflow Graph Operating System Development, Sriram J. Coimbatore

Electrical & Computer Engineering Theses & Dissertations

Implementation of a new dataflow schedule model is the objective of this thesis. The dataflow model algorithm called the resource/dataflow graph model is implemented on a peer-to-peer communication network comprising of six personal computers. This dataflow model is implemented making use of an earlier dataflow model called ATAMM (Algorithm to Architecture Mapping Model) developed by ODU and National Aeronautics and Space Administration (NASA). Development issues include modification of the RDFG testbed operating system and a scheme to transfer data buffers using the ethernet channel from one processor to another processor. This, in turn, equips each sub-module of an application with …

Visual Speech Recognition Using Multiple Deformable Lip Models, Devi Chandramohan

Electrical & Computer Engineering Theses & Dissertations

Motivated by the fact that human speech perception is a bimodal process (auditory and visual), several researchers have designed and implemented automatic speech recognition (ASR) systems consisting of both audio and visual subsystems, and shown improved performance relative to traditional purely auditory systems. Several visual speech reading approaches have used deformable templates to model the shape of a speaker's lips. Deformable templates are models of image objects, which can be deformed by adjusting a set of parameters to match the object in some optimal way, as defined by a cost function. Using a single deformable lip model has disadvantages such …

Scheduling Processors For Distributed, Critical, Real-Time Systems, Hari K. Narasimhamurthy

Electrical & Computer Engineering Theses & Dissertations

The development of a procedure to obtain cyclo-static schedules for distributed, critical real-time applications is presented in this thesis. The applications considered in this thesis are characterized by hard deadlines and periodic inputs. The applica­ tions are described by a data flow graph model which guarantees performance. Given the data flow graph representation, processors are scheduled to complete tasks as specified in the representation. The scheduling technique separates the scheduling of tasks in time and the assignment of processors to tasks. While different criteria exist for task scheduling, a schedule which minimizes latency and maximizes throughput is used in this …

Speech Feature Computation For Visual Speech Articulation Training, Stefan Auberg

Electrical & Computer Engineering Theses & Dissertations

A new version of the Visual Speech Articulation Training Aid was implemented which provides real-time visual feedback for speech articulation training. This version was migrated to a Windows Multimedia PC from a previous version which used a Personal Computer (PC) system and additional specialized and expensive custom hardware. This new version will make the system more available to schools and private users. A new method was developed for computing spectral/temporal features which characterize the speech sounds. In addition to the typical frame-based spectral analysis parameters, the new method represents temporal changes of the spectrum with a small number of features. …

Fault Tolerance In Critical Real-Time Systems, Balaji Tirukarneswaran

Electrical & Computer Engineering Theses & Dissertations

Critical real-time applications require work to be completed before a predefined deadline, else the consequences may be catastrophic. The anticipation of faults in such systems necessitates the need for fault tolerance. Fault tolerance can be achieved in many different ways. A real-time system designer may impose restrictions on any of the system performance measures such as the latency, throughput and number of processors, depending on the type of application. In this work, several different fault tolerant strategies for any given DFG (Data Flow Graph) are discussed. DFG models are developed using the strategies and the resulting worst case performances a.re …

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 …

Generalization Metrics For Neural Modeling Applications In System Identification, Denise M. Reeves

Electrical & Computer Engineering Theses & Dissertations

In this thesis a procedure to design multilayer feedforward networks for system identification with good prediction properties is presented. Central to the design procedure is a means to characterize the prediction capabilities of various trained neural networks. Such knowledge will allow for the identification of the best network design. For system identification purposes, a "good" model is one that is good at predicting, In particular, a good model is one that produces small prediction errors when applied to a set of cross-validation data. We formulate and implement a criterion function designed to measure the size of a trained neural network's …

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 …

Defining Locally Shared Memory Constructs For Special Purpose Parallel Architectures, David J. Nielsen

Electrical & Computer Engineering Theses & Dissertations

Locally shared memory systems offer significant advantages over other parallel processing systems for specific classes of problems. Locally shared memory systems tend to be easier to program because explicit passing of messages is not necessary. The goal in defining a locally shared memory system is to allow only a small number of processors access to any single memory. If this goal is met, locally shared memory systems provide an architecture which is relatively simple to implement.

To make shared memory architectures attractive to designers of special purpose parallel architectures, the architectures must be scalable. To be scalable, the number of …

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 …

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 …

Resource Utilization Model For The Algorithm To Architecture Mapping Model, Rakesh R. Patel

Electrical & Computer Engineering Theses & Dissertations

The analytical model for resource utilization, and the variable node time and conditional node model for the enhanced ATAMM model for a real-time data flow architecture, is presented in this research. The Algorithm To Architecture Mapping Model, ATAMM, is a Petri net based graph theoretic model developed at Old Dominion University, and is capable of modeling the execution of large-grained algorithms on a real-time data flow architecture. Using the resource utilization model, the resource envelope may be obtained directly from a given graph and, consequently, the maximum number of required resources may be evaluated. The node timing diagram for one …

Robot Force Velocity Control Using Expert System For Control Mode Changes, William R. Doggett

Electrical & Computer Engineering Theses & Dissertations

The most important property of an automated mechanical system is reliable execution of a specified task. Automated mechanical systems work best in precisely structured environments where all operations are repeatable. Typically, these systems are difficult to modify and expensive to install. Sensors can be used to detect disturbances, thus reducing hardware cost by offsetting the need for precise rigid construction components. Sensors, however, increase the complexity and cost of the control software. Efficient methods of reacting to sensor information during automated system operation are required to reduce software complexity and expense.

This thesis analyzes a robotic construction task and describes …

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 …

Simulator For Concurrent Processing Data Flow Architectures, Mahyar R. Malekpour

Electrical & Computer Engineering Theses & Dissertations

A software simulator capable of simulating execution of an algorithm graph on a given system under the Algorithm To Architecture Mapping Model (ATAMM) rules is presented in this thesis. ATAMM is capable of modeling the execution of large-grained algorithms on distributed data flow architectures. Investigating the behavior and determining the performance of an ATAMM based system requires the aid of software tools. The ATAMM Simulator presented in this thesis is capable of determining the behavior, performance, and reliability of a system without having to build a hardware prototype. Case studies are performed on four algorithms to demonstrate the capabilities of …