Digital Commons Network^™

Fatigue Behavior Of A Cross-Ply Ceramic Matrix Composite Under Strain Controlled Tension-Tension And Tension-Compression Loading, James J. Gudaitis

Theses and Dissertations

This stuidy investigates the fatigue response of a cross-ply [0/90]_2s Nicalon/Calcium Aluminosillicate (Nicalcc/CAS) ceramic matrix composite at room temperature under strain controlled tension-tension and tension-compression fatigue loading. The primary objectives were to determine strain fatigue limits for both loading cases and to complete a fatigue life diagram (Δe-N) for all tests. Failure mechanisms were also studied. The average initial modulus value for this lay-up was 120 GPa. The ultimate tensile strain was 0.00988 mn/mm (285 MPa). Eight tests were conducted with maximum strains that ranged from 0.00300 mm/mm to 0.00722 mm/mm. The tension-tension fatigue limit was found to be …

Fatigue Behavior Of A Cross-Ply Ceramic Matrix Composite At Elevated Temperatures Under Tension-Tension Loading, Richard J. Tuznik

Theses and Dissertations

A study was conducted which investigated the behavior of a Nicalon/ Calcium-Aluminosilicate (Nicalon/CAS) cross-ply [0/90]_2S ceramic matrix composite at elevated temperatures under tension-tension fatigue loading. Tension-tension fatigue tests were performed with a load ratio of R = 0.10 and a frequency of 10 Hertz at 700°C and 850°C. These results were compared to results from a previous study conducted at room temperature. Material behavior and damage was recorded by fatigue life curves, elastic modulus' maximum and minimum strain, acetate replication techniques, and post-mortem fractography. Analysis of these results showed identical matrix dominated damage behavior at RT and 700°C. Ultimate …

Vibrational Energy Transfer Within The B3Π(0+U) State Of 79Br2 Upon Collision With N2, O2, No, And Sf6, Gregory S. Williams

Theses and Dissertations

Vibrational transfer and electronic quenching in the lower vibrational levels of the ⁷⁹Br₂(B; v'≤3) were investigated using spectrally resolved, temporally resolved pulsed laser induced fluorescence techniques. Spectrally resolved emissions from collisionally populated Br₂(B) vibrational levels were observed for N₂, O₂, NO, and SF₆collision partners. The vibrational transfer was efficient in the nonpredissociative vibrational levels and is adequately described by the Montroll-Shuler model. An average fundamental vibrational transfer rate coefficient of k_v(l,0)=3.4(±0.6) x 10^-11 cm³/molec-sec predicts the vibrational transfer rates for the 0≤v'≤3 collisions with …

Developing Realistic Cooperative Behaviors For Autonomous Agents In Air Combat Simulation, Dean P. Hipwell

Theses and Dissertations

This thesis investigated, developed and implemented cooperative decision-making behaviors in an air combat simulation by using a knowledge-based system. Knowledge-based systems were well suited for this task because of built- in features such as inference engines and rule-based constructs. This thesis addresses the specific problem of generating autonomous forces for inclusion in the Advanced Research Projects Agency Distributed Interactive Simulation program. Existing autonomous forces implementations lacked flexibility, realistic behaviors, real-time planning and other features. The simulation system in this thesis addresses the problem of realistic behavior by modeling pilot decision processes rather than aircraft platforms. The system is based on …

Alternative Architectures For Domain-Oriented Application Composition And Generation Systems, Warren E. Gool

Theses and Dissertations

This thesis presents a formalized framework for comparing the structure and semantics of software architectures. The framework uses object diagrams for analyzing the structure of the architectures and the axiomatic approach for analyzing the semantics. This framework is used to compare the Object Connection Update OCU model developed by the Software Engineering Institute against four other software architectures VHDL defined by Lipsett, MetaH defined by Honeywell, microRapide defined by Luckham, and hierarchical software systems as defined by Batory. The goal of the comparison was to evaluate the OCU model for suitability within prototype application composition and generation systems. This research …

Radar Cross Section Visualization Using Sample Buffer Progressive Refinement Volume Rendering, Alain L. Jones

Theses and Dissertations

This study developed a prototype for an interactive radar cross section visualization software system. The system, hosted on a Silicon Graphics workstation, is intended to support aircrews, mission planners, aircraft designers, and others who require an understanding of aircraft radar cross section characteristics. The input to the system is a set of radar cross section samples taken at various aspect angles. A pre-processor developed as part of this study transforms the input radar cross section data into a three-dimensional cuberille data volume. This data volume is then visualized using an interactive volume renderer. The interactive volume renderer implements progressive image …

Synthetic Battlebridge: Information Visualization And User Interface Design Applications In A Large Virtual Reality Environment, Kirk G. Wilson

Theses and Dissertations

With shrinking budgets and fewer personnel, future military training will rely heavily on simulated environments. The goal for this training is to reduce cost while maintaining readiness and unparalleled capability for all levels of military command. This thesis effort, the Synthetic Battle Bridge SBB , provides a real-time simulated environment for military commanders to observe on-going computer simulations of varying participation levels and helps them wring the most from a simulation. The SBB, designed for higher ranking personnel with little time to spend learning how to run the system, must exhibit three capabilities ease-of-use, long-term retention, and adaptability. Based on …

Performance Measurement Of Three Commercial Object-Oriented Database Management Systems, Timothy J. Halloran

Theses and Dissertations

The goal of this thesis was to study the performance of three commercial object-oriented database management systems. The commercial systems studied included Itasca, sold by Itasca Systems Incorporated Matisse, sold by Intellitic International and ObjectStore, sold by Object Design Incorporated. To examine performance of these database management systems two benchmarks were run the OO1 benchmark and a new AFIT Simulation benchmark. The OO1 benchmark was designed, implemented, and run on all three database management systems. ObjectStore was our top performer on all configurations of the OO1 benchmark. The AFIT Simulation benchmark was designed, implemented, and run on the ObjectStore database …

Enhanced Tracking Of Airborne Targets Using Forward Looking Infrared And Laser Return Measurements, Patrick J. Grondin

Theses and Dissertations

The Air Force Institute of Technology has been involved in developing Kalman filter based trackers of ballistic missiles for 15 years. The goal of this thesis is to develop a Multiple Model Adaptive Estimator MMAE that tracks the missile plume using a forward looking infrared sensor and the missile hardbody center-of-mass additionally using low energy laser returns for the purpose of directing a high power laser to incapacitate the missile. The missile plume pogos about an offset equilibrium point relative to the hardbody center-of-mass with an amplitude and frequency of oscillation that are not precisely known a priori. The MMAE …

Performance Comparison Of Shearing Interferometer And Hartmann Wave Front Sensors, Timothy L. Pennington

Theses and Dissertations

The resolution of optical imaging systems is severely degraded from the diffraction limit by the random effects of the atmosphere. Techniques exist to compensate for the atmospheric turbulence, one of which is adaptive optics. A critical component in the adaptive optics system is the wavefront sensor. Presently, two types of sensors are being used-the Hartmann-Shack Wavefront Sensor and the Shearing Interferometer. Previous studies have compared these two sensors and found them to perform identically for a point source. However, to date, no comparison has been performed for an extended source and subaperture spacing larger than the correlation length of the …

Filtering, Coding, And Compression With Malvar Wavelets, Stephen R. Hall

Theses and Dissertations

This thesis develops and evaluates a number of new concepts and tools for the analysis of signals using Malvar wavelets lapped orthogonal transforms . Windowing, often employed as a spectral estimation technique, can result in irreparable distortions in the transformed signal. By utilizing the Malvar wavelet, any signal distortion resulting from the transformation can be eliminated or cancelled during reconstruction. This is accomplished by placing conditions on the window and the basis function and then incorporating the window into the orthonormal representation. Paradigms for both a complex-valued and a real-valued Malvar wavelet are summarized. I-lie algorithms for the wavelets were …

Business Process Improvement Applied To Written Temporary Duty Travel Orders Within The United States Air Force, Philip W. Mcdowell, David W. Morgan

Theses and Dissertations

This study analyzed the process currently endemic to the activity of producing written TDY orders. Business Process Improvement BPI methodology using IDEF ICAM Integrated Computer Aided Manufacturing Definition and Activity Based Costing methods were used for this study. The objectives of the written TDY order activity were determined as identifying the travelers and verifying authenticity of the travel requirement and subsequent entitlements. Processing the TDY information, generating the TDY order, and processing the TDY order showed activities that add no value or limited value for either the traveler or the government. The activity costs incurred to produce a written TDY …

Interrogatives In Yanomám, Richard A. Thiele

Theses and Dissertations

This thesis is a general linguistic description of yes-no and information questions in Yanomám (a member of the Yanomami language family of Brazil and Venezuela) in the descriptive/typological tradition, including morphosyntax and semantics, appropriate responses, certain discourse-pragmatic conditions of their use (such as bias and focus), and intonation patterns.

Some things in the Yanomám language that are typologically unusual are an information question system that utilizes just one interrogative word, interaction of temporal-evidential particles with questions, and the occurrence of hortative constructions in questions.

My sources of information include the limited published works and articles on the language, previously unpublished …

An Investigation Of The Effects Of Gender And Specificity Of Information On Diagnosis, Scott W. Sumerall

Theses and Dissertations

Results of studies investigating the possible presence of bias in psychotherapy are equivocal. Past studies have not taken into consideration the amount of information provided to clinicians and therefore have varied this dependent variable unsystematically from study to study. The current study explored the effects of the gender of the psychologist, gender of the client, and level of information provided upon which to base decisions on diagnostic and treatment decisions. Three cases varying gender of the client and the amount of information given were mailed to 814 psychologists listed in the National Register of Health Service Providers in Psychology. Respondents …

The Nuclei Of Discontent, B. Jane Overmoe

Theses and Dissertations

The purpose of this study was to disclose a dramatic political event in droughtstricken North Dakota during the so-called "Dirty Thirties." After completing a Communist investigation for the Americanism Committee of the American Legion Auxiliary for the Department of North Dakota, Agnes Kjorlie Geelan began speaking engagements to inform the public about the results of the report and to persuade members of the American Legion Auxiliary to act upon the information. This study specifically analyzed the rhetoric of Geelan’s "Nuclei of Discontent" Address at the American Legion Auxiliary State Convention in June 1932 in Devils Lake, North Dakota.

To provide …

A Comparison Of Teacher Employment Elements In Master Contract Provisions Among Fourteen Northeast North Dakota Schools, Mary J. Lystad

Theses and Dissertations

No abstract provided.

Modal Control Of A Satellite In An Unstable Periodic Orbit About The Earth-Sun Interior Lagrange Point, Douglas J. Hopper

Theses and Dissertations

A periodic halo orbit which exists about the interior Lagrange point for the Earth-sun system was decomposed using Floquet theory into modal variables, which are dynamically decoupled subspaces for the six degree of freedom system. Modal control consisted of evaluating the diverging mode and maneuvering to counteract its divergence. In the unperturbed system, this was successful. Control costs were low, and the significance is that the controller did nothing to suppress modes that were oscillatory or converging. The effect of the moons motion allowed the scheme to operate with reasonable control costs, but the effect of eccentricity caused divergence in …

A Study Of Graphite Peek Composite With Central Elliptical Holes Under Tension, Bill J. Lau

Theses and Dissertations

This study investigated the stress-strain response and failure modes of Graphite/Polyetheretherketone (Gr/PEEK) tension specimens containing a central elliptical hole. Both experiments and finite element numerical analyses were conducted. Test specimens included seven layups and three hole geometries; three of each combination were tested. The holes consisted of an ellipse with major axis aligned with the load axis, an ellipse with major axis transverse to the load axis, and a circle. Strain gages were located adjacent to the hole and midway between the hole and tab on all specimens. Strain data was used to plot stress-strain response. The analysis utilized a …

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 …

Investigation Into Formalization Of Domain-Oriented Parallel Software Development, Daniel P. King

Theses and Dissertations

This research investigates the conceptual design of a semi-automated platform for parallel software development. The proposed semi-automated environment applies transformational techniques and domain-specific knowledge to a parallel software development process. Domain-specific and software design knowledge interact within the transformational development process in the creation of a software application. The underlying parallel specification language requires a set of parallel composition operators in order to capture an application’s concurrent properties. A set of parallel composition operators is proposed that consists of parallel composition, parallel enumeration, nondeterministic choice, sequential composition specific communication and synchronization variable types are also proposed. A semi-automated environment based …

Developing A Graphical User Interface To Support A Real-Time Digital Signal Processing System, Jeffrey C. Miller

Theses and Dissertations

A graphical software user interface for a VMEbus-based real-time digital signal processing system was designed. Use, requirements were defined and the Rumbaugh object-oriented analysis and design technique was applied to analyze the requirements and produce an object-oriented design. The software design includes a graphical, mouse- and keyboard driven user interface, specialized hardware driver modules, and operating system interfaces. An implementation plan was also developed to map the design into the C programming language using existing system code, automatically generated code, and newly written code. Based on the implementation plan, a limited software system prototype w successfully developed and demonstrated. The …

Applying Visual Information Management Software For Electric Utilities Automated Mapping, Barry J. Owens

Theses and Dissertations

No abstract provided.

Personality And Demographic Characteristics Of Victims Of Sexual Abuse And Self-Mutilation, Shirley J. Rader

Theses and Dissertations

The purpose of this study was to compare demographic and personality characteristics of a group of inpatients at a psychiatric hospital in New York State who were sexually abused and who were self-mutilators (N = 64) with: a group of sexually abused inpatients (N = 42); a group of self-harming inpatients (N = 25); and a group of selected general psychiatric inpatients (N = 25). All subjects were 18 years of age or older at the time of the study and over 90% of the participants were females.

It was hypothesized that sexually abused/self-mutilating patients would show greater similarity to …

Production Activity And Performers At The Metropolitan Theatre, Grand Forks, North Dakota 1898 - 1911, Dawn D. Drake

Theses and Dissertations

This study documents and analyzes the production activity and the quality of the celebrity performers appearing at the Metropolitan Theatre in Grand Forks, North Dakota, during the years of 1898 to 1911. The production activity at the theatre is categorized into seven groups of production: legitimate drama, Shakespeare/'classics, melodramas, minstrels, opera/musicals, vaudeville/burlesque and special productions. The quality of performers is judged by their relative status in American theatre history. Both of these elements were, during this period, heavily influenced by the Theatrical Syndicate.

Research for this study includes searching newspaper advertisements and publicity for the productions found in The Grand …

Health Care Perspectives Of Consumers And Providers In Northwest Minnesota, Mary D. Wiersma

Theses and Dissertations

An overwhelming number of reports in the literature identify common problems within our health care system and the unique problems faced by rural areas regarding health care delivery. A paucity of research exists that addresses problems of rural health care as perceived by consumers and health care providers.

In this study, the perceived health care needs, wants, and demands of consumers and providers in a single region of a Midwestern state were sampled to clarify the priorities of these groups. Orem's self-care deficit theory of nursing (S.C.D.N.T.) was used as the theoretical framework for this study. A selected group of …

Predictors Of Success On The Uniform Certified Public Accountant Examination, Mark E. Skean

Theses and Dissertations

The purposes of this study were to identify personal and intellectual characteristics associated with successful performance of first-time candidates on the uniform Certified Public {CPA) Examination and to develop prediction equations for success on each of the four exam sections.

CPA candidates who received undergraduate degrees from the University of North Dakota and who wrote the exam in 1988, 1989, or May 1990 were eligible for the study. Data for the 39 characteristics were gathered from candidate questionnaires and the university registrar.

Exam success was measured in several ways. An individual with a higher score, a passing grade on an …

Use Of Chlorine Dioxide To Remove Fish Pathogens From Garrison Diversion Water, Wayne C. Hustoft

Theses and Dissertations

This report considers the use of chlorine dioxide as an alternate disinfectant for the removal of biota from Garrison Diversion water. Laboratory testing has shown that chlorine may not be an acceptable disinfectant because it can produce carcinogens from side reactions with constituents found in natural surface waters.

This study used Lake Sakakawea water collected at the Snake Creek Pumping Station located on the eastern shore. Water samples were of direct filtration effluent from a laboratory scale filter column. samples were gathered at several different turbidity levels. The "DPD" method, as published in "Standard Methods for the Analysis of Water …

Design And Construction Of The Aerobot Robotic Manipulator (Arm), William L. Cochran

Theses and Dissertations

This thesis designed, constructed, and tested a robotic arm for the Aerobot Aerial Robot. The main purpose of the ARM is to enable the Aerobot to retrieve objects for use in an annual robotics competition. Design of the ARM involved synthesizing the characteristics of simplicity, weight, strength, and size. The result was a three-degree-of-freedom manipulator that uses electric motors, cable linkages, and telescoping tubes to access a work space below the Aerobot. Forward and inverse kinematics were investigated to enable automation of the ARM. Data was collected from infrared sensors to validate the model. Manipulation of the ARM is presently …

Analysis Of The Effects Of Wake Passage On Heat Transfer In A Linear Turbine Cascade, Kevin S. Allen

Theses and Dissertations

This study investigated the effect of wake passage on the heat transfer in a linear turbine cascade. The apparatus used was the Air-Force Institute of Technology linear Turbine Cascade Test Facility (TCTF). The TCTF was fitted with a be Pulley system to facilitate a series of translating bars. The bars, when passed d upstream of the cascade, created a series of wakes. The parameters varied were freestream model Reynolds number and bar conditions, i.e. , bars in, bars out, and bar passing frequency. One blade in the TCTF was instrumented to allow pressure and temperature measurements at discrete points on …

Shock Wave Interaction With L-Shaped Structures, Richard C. Miller

Theses and Dissertations

This study investigated the interaction of shock waves with L-shaped structures using the CTH hydrodynamics code developed by Sandia National Laboratories. Computer models of shock waves traveling through air were developed using techniques similar to shock tube experiments. Models of L-shaped buildings were used to determine overpressures achieved by the reflecting shock versus angle of incidence of the shock front. An L-shaped building model rotated 45 degrees to the planar shock front produced the highest reflected overpressure of 9.73 atmospheres in the corner joining the two wings, a value 9.5 times the incident overpressure of 1.02 atmospheres. The same L-shaped …