Digital Commons Network^™

Pid Tuning Of Plants With Time Delay Using Root Locus, Greg Baker

Master's Theses

This thesis research uses closed-loop pole analysis to study the dynamic behavior of proportional-integral-derivative (PID) controlled feedback systems with time delay. A conventional tool for drawing root loci, the MATLAB function rlocus() cannot draw root loci for systems with time delay, and so another numerical method was devised to examine the appearance and behavior of root loci in systems with time delay.

Approximating the transfer function of time delay can lead to a mismatch between a predicted and actual response. Such a mismatch is avoided with the numerical method developed here. The method looks at the angle and magnitude conditions …

Construction And Simplicity Of The Large Mathieu Groups, Robert Peter Hansen

Master's Theses

In this thesis, we describe the construction of the Mathieu group M₂₄ given by Ernst Witt in 1938, a construction whose geometry was examined by Jacques Tits in 1964. This construction is achieved by extending the projective semilinear group PΓL₃(F₄) and its action on the projective plane P²(F₄). P²(F₄) is the projective plane over the field of 4 elements, with 21 points and 21 lines, and PΓL₃(F₄) is the largest group sending lines to lines in P²(F₄).This plane has 168 6-point subsets, hexads, with the …

Numerical Investigation Of Fundamental Physics For Flows Over Expansion And Compression Corners, Freddy Ngo

Master's Theses

Oblique shocks and expansion waves are commonly found in aerospace applications such as wings and nozzles. These types of shocks change the properties of the flow, thus causing changes in the lift, drag, and/or heat transfer. Hypersonic flow is important to study as its impacts are significant. In this thesis, computational fluid dynamics (CFD) is utilized to characterize the physics of the flow. Parametric studies of the Mach number and turning angle were conducted. Simulations included both inviscid and viscous flows to demonstrate the effects of boundary layer on flow properties. The majority of the viscous flows were focused on …

Public Awareness About Global Warming In Hyderabad, India, Vani Sarraju Rao

Master's Theses

This study addressed public perceptions and awareness about global warming in India through a survey of 851 subjects in the city of Hyderabad in the year 2007. A stratified sample of nine segments of society showed that, although people consider global warming a serious problem, they do not clearly understand its causes, impacts, and solutions. The data analyses using paired T-tests indicated differences in levels of awareness about global warming, across age and education. ANOVA and regression analysis suggested that levels of awareness among respondents varied according to their occupation. The degree of seriousness with which subjects viewed global warming …

Yig-Sphere-Based Phase Shifter For X-Band Phased Array Applications, Donald C. Benson

Master's Theses

A novel technique for effecting phase shift of X-band signals has been developed and analyzed for use with quadrature amplitude modulation (QAM) of signals in a phased array application, and the impact of this phase shifter on error vector magnitude (EVM) has been quantified. A commercially available filter consisting of yttrium iron garnet (YIG) spheres was characterized by means of a network analyzer. The gain and phase response was measured across a 25 MHz frequency band centered at 10 GHz, while the filter was tuned in frequency steps such that a 360° range of phase shifts was achieved. The S-parameters …

The Manual Flight Skill Of Airline Pilots, Antonio Puentes

Master's Theses

The manual flight ability of commercial airline pilots has been scrutinized

after several aviation disasters in the first decade of the 21st century where pilot error has been a contributing cause. Voluntary pilot incident reports from the National Aeronautics and Space Administration's Aviation Safety Reporting System (ASRS) were examined as one method to determine the prevalence of manual flight skill decline among airline pilots. The investigation studied reports from unstabilized approach to landings where the pilots manually controlled the aircraft during descent. An analysis of the ASRS reports from pilots flying traditional flight deck aircraft compared with pilots flying aircraft …

Land Use Interpretation In Flood Damage Estimation, Sharon Michelle Metzler

Master's Theses

This thesis examines the role of geographic land use interpretation in flood damage estimation. Sample flood data were drawn from the 1998 flood event along San Francisquito Creek in northern Santa Clara County, California. Spatial flood data for the event were collected from the Santa Clara Valley Water District (the District); depth-damage factors and the flood damage equations were both collected from US Army Corps of Engineers' (the Corps) publications; and spatial parcel data were collected from the Santa Clara County Tax Assessor's office (the Assessor).

This study computes flood damages per parcel using the Corps' recommended equations. Within that …

Antenna Design: A Crystallographical Approach, Luke Macvicker Snow

Master's Theses

The goal of this thesis was to design a switched beam antenna by applying the principles of crystallography. The main benefit of this approach is that simple design equations can be derived from crystallography and readily applied to the design of a steerable beam antenna. Before using equations from crystallography in an antenna design, the equations are first verified. One of the best known laws of crystallography, namely Bragg's Law, is verified both by software simulation, and experimentally from the radiation patterns of a prototype antenna.

One set of simulations used to verify Bragg's Law involved varying the angles of …

A Mathematical Approach For Predicting Harbor Seal Haul-Out, Jonathan Daniel Cowles

Master's Theses

Harbor seals haul out in response to various environmental factors such as tide, current, time of day, wind, and surf. Mathematical modeling techniques can be used to determine which of these variables are important and to predict the number of seals that will haul-out in a given set of environmental circumstances. Haul-out counts were recorded every hour for 16 hrs per day over two 14-d tidal cycles at a site in Washington State. Deterministic environmental variables (tide height, current velocity, solar elevation, and time of day) were used to create 37 alternative models, which were then compared to the haul-out …

Policy Appears Upon The Scene, Hand In Hand With Poverty: An Analysis Of The Moderating Effects Of Teacher Attitude On The Relationship Between Professional Development And Student Achievement., Kristen Beth Adler

Master's Theses

Massive deficits in local, state and national education budgets are forcing schools to adapt their spending to align with these reductions. Rather than merely increasing or decreasing resources, the effectiveness of resource allocation is demanding renewed attention at all levels of educational expenditure. The purpose of this study is to assess the effectiveness of teacher professional development across five campuses at Chicago International Charter School. It is the goal of this project to examine how teacher professional development directly impacts student performance, as well as to evaluate whether this relationship is moderated by teacher attitude towards professional development activities. It …

Supporting Introductory Test-Driven Labs With Webide, Thomas C. Dvornik

Master's Theses

WebIDE is a new web-based development environment for entry-level programmers with two primary goals: minimize tool barriers to writing computer programs and introduce software engineering best practices early in a student's educational career. Currently, WebIDE focuses on Test-Driven Learning (TDL) by using small iterative examples and introducing lock-step labs, which prevent the student from moving forward until they finish the current step. An initial set of labs and evaluators were created as examples of how to use WebIDE and were used in a pilot study in a CS0 course where students were split into two groups, one that used WebIDE …

The Effects Of Anti-Price Gouging Legislation On Supply Chain Dynamics, Jason Edward Maynard

Master's Theses

The purpose of this thesis is to model the effects of anti-price gouging (APG) legislation on the costs to businesses during the recovery period of a disaster. A system dynamics model of a business’s replenishment procedures is used to simulate the effects of APG legislation on business performance. Economists have published expansive research on the effects of price ceilings on supply and demand, but there is little research evidence on the operational consequences of price ceiling legislation on business costs. APG legislation increases consumer’s forward buying and shortage gaming after a disaster by removing price incentives to be frugal. Forward …

Benchmarks For Transition: Do St. Louis High Schools Promote Graduates That Can Make The Transition To Higher Education?, Kevin Harrman

Master's Theses

Are St. Louis area high schools designed to create graduates that are prepared to enter schools of higher education, or are their graduation requirements structured such that graduates even qualify for entrance to higher education institutions? This study is geared towards answering this question and will do so by comparing two lines of inquiry. First this study will analyze four sets of three randomly picked area high schools (three sets designated by per capita income and one set of private catholic schools). Information will be gathered concerning graduation requirements and how many Advanced Placement and/or International Baccalaureate courses are available. …

Predictors Of Academic Achievement And Failure Among Low-Income Urban African American Adolescents: An Ecological Perspective, Israel Moses Gross

Master's Theses

Predictors of academic achievement among urban low-income African American adolescents have primarily been investigated by examining "main effects," or limited interactions with conventional statistical techniques. This paper adds to the literature by examining the factors that influence academic outcomes among this population within an ecological systems framework. This allowed for a comprehensive understanding of how numerous protective and risk factors, across ecological settings, interact to influence academic outcomes.

Optimal Data Analysis (ODA) was employed to create prediction models for mathematic and reading achievement. ODA allowed for the examination of a vast number of variables in one statistical model without increasing …

The Decentralization And Centralization Of Curriculum In The Primary Education Of Burkina Faso, Simon A. Ziba

Master's Theses

In Burkina Faso, a decree which transfers competences and resources related to basic education to municipalities, does not mention the case of curriculum. This study seeks to understand how do educational policymakers in Burkina Faso explain why educational decentralization initiatives have not heretofore affected curriculum issues, and how do they view the possibility and desirability of a decentralized curriculum. It uses qualitative and quantitative methods. This nationwide study has participants who are primary education bureaucrats and educational policymakers at the central, regional and provincial levels of the ministry in charge of basic education. The results of this study show that …

Politics And Pupils: How The Conflict Between The Washington Teachers' Union And The Fenty Administration Impacted Education Reform In The District Of Columbia, Maureen Therese Costello

Master's Theses

Upon gaining mayoral control of DCPS on June 12, 2007, Mayor Fenty and Chancellor Rhee immediately challenged DCPS procedure and outspokenly called for increased accountability from all stakeholders. Washington's contemporary reform reveals that not only was teacher accountability an important component of reform policy in Mayor Fenty and Chancellor Rhee's educational ideology, it functioned as an essential standard. This document based analysis utilizes the WTU/DCPS teachers' contract, DCPS and WTU press releases, and the framework of the IMPACT/IMPACTplus performance-based pay system to examine the relationship between the WTU and the Fenty Administration amidst Chancellor Rhee's reform policies. The turbulent relationship …

The Influence Of Neuroticism On Stress Perception And Its Resultant Negative Affect, Irum Saeed Abbasi

Master's Theses

There is contemporary literature reporting the role of the neuroticism (N) personality type in the stress process. People with elevated neuroticism experience more interpersonal stressors, perceive daily events as more negative, and use maladaptive ways to combat stressors. This thesis explores the influence of neuroticism on stress perception and the associated negative affect. In the current study, mood and stress perception of pre-screened college students who scored high and low on the neuroticism subscale were manipulated, with a laboratory psycho-social stressor, after their moods were initially neutralized to their respective base levels. Later, their mood and stress perception were manipulated …

The Heart And Mind At Work: The Effects Of Implicit And Explicit Reasoning On Performance Appraisal, Scott Ryan

Master's Theses

No abstract provided.

Implementation Of The Clas12 Htcc Into Gemc, Nathan A. Harrison

Master's Theses

No abstract provided.

Intelligent Planning And Assimilation Of Auv-Obtained Measurements Within A Roms-Based Ocean Modeling System, Benjamin J. Davini

Master's Theses

Efforts to learn more about the oceans that surround us have increased dramatically as the technological ability to do so grows. Autonomous Underwater Vehicles (AUVs) are one such technological advance. They allow for rapid deployment and can gather data quickly in places and ways that traditional measurement systems (bouys, profilers, etc.) cannot. A ROMS-based data assimilation method was developed that intelligently plans for and integrates AUV measurements with the goal of minimizing model standard deviation. An algorithm developed for this system is first described that optimizes paths for AUVs that seeks to improve the model by gathering data in high-interest …

Functional Reactive Musical Performers, Justin M. Phillips

Master's Theses

Computers have been assisting in recording, sound synthesis and other fields of music production for quite some time. The actual performance of music continues to be an area in which human players are chosen over computer performers. Musical performance is an area in which personalization is more important than consistency. Human players play with each other, reacting to phrases and ideas created by the players that they are playing with. Computer performers lack the ability to react to the changes in the performance that humans perceive naturally, giving the human players an advantage over the computer performers.

This thesis creates …

Assessing Potential Industry Growth For Economic Development In Oakland, Ca, Sonia Aery

Master's Theses

This study prepares a set of career ladders for the population of Oakland. Career ladders are long-term progression pathways to help individuals advance, particularly in high wage, high growth careers. Career ladders combine different statistics on the demographics of a population with statistics about the area’s economic vitality and potential. This combination helps to identify the potential to strengthen an area’s economy and enhance individuals’ qualifications and wages.

One of the main reasons that people and large firms are attracted to a given city is the potential for economic stability. A stable economy is the result of the availability of …

Water Quality Performance Of A Reciprocating Biofilm Reactor For Treatment Of Dairy Wastewater, Jason Patrick Kane

Master's Theses

Removal of organic matter and nitrogen from concentrated wastewaters is often a complex and costly process that is rarely implemented in animal agriculture, such as the dairy industry, despite regulatory pressures and the high cost of land for manure application in some regions. This paper describes results from the first implementation for treatment of dairy farm wastewater of the relatively simple ReCip® technology. ReCip® typically consists of two basins filled with rock aggregate through which wastewater is flowed in series. One basin is full of wastewater and the other is only partially full. Wastewater is alternately pumped between the basins …

A System For Measuring Radiation Induced Chemical Products In Atmospheric Gases Using Optical Detection Methods, Tyler Webster Reese

Master's Theses

This research is a part of an effort to characterize the chemical products generated by radiation interacting with atmosphere. One method of detecting ionizing radiation is to monitor the radiation induced products in the atmosphere around the source. This project explored the potential for using Cavity Ringdown Spectroscopy to evaluate the presence of chemical products generated by the air-radiation interaction near an alpha radiation source. In particular, measurements of ozone concentration within a controlled atmosphere chamber as affected by radiation exposure were obtained.

The first portion of this thesis provides brief reviews of ionizing radiation and ozone formation as well …

Nonlinear Modeling Of A Sustainable Material, Jorien Gill Baza

Master's Theses

This study developed a nonlinear constitutive model for a sustainable orthotropic material. Existing methods for constitutive models of wood were improved upon to include the nonlinear stress-strain response not only in the two orthogonal axes but at any orientation to the strong axis of the material. This method also simplifies the nonlinear stress-strain relationships into bilinear stress-strain curves which can be valuable in hand calculations as well as finite-element analyses. The effectiveness of the proposed constitutive model is demonstrated by comparing bilinear stress-strain predictions to experimental data.

Control Of Longitudinal Pitch Rate As Aircraft Center Of Gravity Changes, John Andres Cadwell Jr.

Master's Theses

In order for an aircraft to remain in stable flight, the center of gravity (CG) of an aircraft must be located in front of the center of lift (CL). As the center of gravity moves rearward, pitch stability decreases and the sensitivity to control input increases. This increase in sensitivity is known as pitch gain variance. Minimizing the pitch gain variance results in an aircraft with consistent handling characteristics across a broad range of center of gravity locations.

This thesis focuses on the development and testing of an open loop computer simulation model and a closed loop control system to …

Terrain Impostors, William Hamilton Hess

Master's Theses

Interactive software applications which need to render large terrain meshes can suffer from slow frame rates if the geometry of the terrain is sufficiently dense. However, the viewing angle to many distant features of the terrain does not change rapidly with respect to time. If the movement of the viewing position is limited to continuous motion and restrained to a known speed, many terrain features may be rendered once in high detail and reused for several frames.

This thesis proposes a method to increase the rendering speed of large complex terrains by splitting the terrain into contiguous chunks. If a …

Modeling And Numerical Investigation Of Hot Gas Defrost On A Finned Tube Evaporator Using Computational Fluid Dynamics, Oai The Ha

Master's Theses

Defrosting in the refrigeration industry is used to remove the frost layer accumulated on the evaporators after a period of running time. It is one way to improve the energy efficiency of refrigeration systems. There are many studies about the defrosting process but none of them use computational fluid dynamics (CFD) simulation. The purpose of this thesis is (1) to develop a defrost model using the commercial CFD solver FLUENT to simulate numerically the melting of frost coupled with the heat and mass transfer taking place during defrosting, and (2) to investigate the thermal response of the evaporator and the …

Development Of A Subject Specific Finite Element Model Used To Predict The Effects Of A Single Leg Extension Exercise, Garrett Thomas Gleeson

Master's Theses

The study presented attempts to prove the concept that mechanical changes in the structure of a bone can be predicted for a specific exercise by a subject specific model created from CT data, MRI data, EMG data, and a physiologic FE model. Previous work generated a subject specific FE model of a femur via CT and MRI data as well as created a set of subject specific biomechanical muscle forces that are required to perform a single leg extension exercise. The FE model and muscle forces were implemented into a single leg extension FE code (ABAQUS) along with a specialized …

Parameter Estimation Of Fundamental Technical Aircraft Information Applied To Aircraft Performance, Michael Vallone

Master's Theses

Inverse problems can be applied to aircraft in many areas. One of the disciplines within the aerospace industry with the most openly published data is in the area of aircraft performance. Many aircraft manufacturers publish performance claims, flight manuals and Standard Aircraft Characteristics (SAC) charts without any mention of the more fundamental technical information of the drag and engine data. With accurate tools, generalized aircraft models and a few curve-fitting techniques, it is possible to evaluate vehicle performance and estimate the drag, thrust and fuel consumption (TSFC) with some accuracy. This thesis is intended to research the use of aircraft …