Digital Commons Network^™

Evolutionary Computing Driven Search Based Software Testing And Correction, Joshua Lee Wilkerson

Doctoral Dissertations

"For a given program, testing, locating the errors identified, and correcting those errors is a critical, yet expensive process. The field of Search Based Software Engineering (SBSE) addresses these phases by formulating them as search problems. This dissertation addresses these challenging problems through the use of two complimentary evolutionary computing based systems. The first one is the Fitness Guided Fault Localization (FGFL) system, which novelly uses a specification based fitness function to perform fault localization. The second is the Coevolutionary Automated Software Correction (CASC) system, which employs a variety of evolutionary computing techniques to perform testing, correction, and verification of …

Periodic Q-Difference Equations, Rotchana Chieochan

Doctoral Dissertations

"The concept of periodic functions defined on the real numbers or on the integers is a classical topic and has been studied intensively, yielding numerous applications in every kind of science. It is of importance that the real numbers and the integers are closed with respect to addition. However, for a number q > 1, the so-called q-time scale, i.e., the set of nonnegative integer powers of q, is not closed with respect to addition, and therefore it was not possible to define periodic functions on the q-time scale in an obvious way. In this thesis, this important open problem has …

A Progressive Collapse Evaluation Of Steel Structures In High Temperature Environment With Optical Fiber Sensors, Ying Huang

Doctoral Dissertations

"In the process of a progressive failure of steel structures in a post-earthquake fire, real-time assessment and prediction of structural behaviors are of paramount significance to an emergency evacuation and rescue effort. However, existing measurement technologies cannot provide the needed critical data such as large strains at high temperature. To bridge this gap, a novel optical fiber sensor network and an adaptive multi-scale finite element model (FEM) are proposed and developed in this study. The sensor network consists of long period fiber gratings (LPFG) sensors and extrinsic Fabry-Perot interferometer (EFPI) sensors or their integration. Each sensor is designed with a …

The Pricing Of Multiple Exercisable American-Style Real Options, Yu Meng

Doctoral Dissertations

"Real options embedded in a project provide management with the flexibility to alter initial investment decisions, thus making them a practical tool for project planning and budgeting. Additional values are contributed to the underlying project due to the flexibilities that are provided by real options. This dissertation presents two models for pricing multiple exercisable American real options, one that employs the binomial tree method and the other one that employs the finite difference method. Different examples of multiple exercisable real options are discussed to demonstrate the two pricing models. Interactions between options and reality constraints are also considered. These two …

Surface Expressions Of Discontinuities, And The Estimation Of Their 3-D Orientations Using Combined Lidar And Optical Imaging, James Nii Aboh Otoo

Doctoral Dissertations

"The importance of the collection and analysis of data on discontinuities cannot be overemphasized. Problems which include sampling difficulties, risks, limited access to rock faces and exposures, and the delay in data collection has led to a high need for data collection tools and analysis techniques that can overcome these problems.

Discontinuities manifest themselves as either traces or as facets. Traces are linear features that intersect with both the discontinuity and the rock cut. Facets are the actual discontinuity surfaces that are exposed in the rock cut. Facets can be natural or induced. Identifying a facet as either natural or …

Lyapunov Based Optimal Control Of A Class Of Nonlinear Systems, Hassan Zargarzadeh

Doctoral Dissertations

"Optimal control of nonlinear systems is in fact difficult since it requires the solution to the Hamilton-Jacobi-Bellman (HJB) equation which has no closed-form solution. In contrast to offline and/or online iterative schemes for optimal control, this dissertation in the form of five papers focuses on the design of iteration free, online optimal adaptive controllers for nonlinear discrete and continuous-time systems whose dynamics are completely or partially unknown even when the states not measurable. Thus, in Paper I, motivated by homogeneous charge compression ignition (HCCI) engine dynamics, a neural network-based infinite horizon robust optimal controller is introduced for uncertain nonaffine nonlinear …

A Socio-Technical Analysis Of Widespread Electric Vehicle Adoption, Onanwa Nneka Egbue

Doctoral Dissertations

A combination of high fuel costs, concerns about petroleum availability, and environmental issues associated with conventional vehicles powered by fossil fuels are driving interests in electric vehicles (EVs). Large-scale deployment of EVs can play a significant role in addressing some of these problems. In spite of the benefits of EVs, several obstacles need to be overcome before EVs will be widely adopted. This research focuses on two socio-technical issues that affect widespread adoption and sustainability of EVs, consumer attitudes and perceptions, and supply chain risks of raw materials for EV battery technology. A major barrier is that consumers tend to …

Measuring The Orientations Of Hidden Subvertical Joints In Highways Rock Cuts Using Ground Penetrating Radar In Combination With Lidar, Adnan Mohammed Aqeel

Doctoral Dissertations

"Mapping discontinuities in rock cuts and measuring their orientations is crucial in assessing the stability of rock masses. This can be done usually using manual methods such as scanline or advanced techniques such as LIDAR. However, these methods are used only to map exposed discontinuities which may cause underestimation for slope stability. Accordingly, ground penetrating radar (GPR) has been recently used to detect such hidden discontinuities.

The used 400 MHz monostatic GPR antenna was significantly able to detect and map hidden subvertical joints within 4 m depths in five sandstone highways rock cuts and within 3 m depths in two …

Addressing Control And Capacitor Voltage Regulation Challenges In Multilevel Power Electronic Converters, Hossein Sepahvand

Doctoral Dissertations

Multilevel power electronic converters are the current industry solutions for applications that demand medium voltage, reasonable efficiency, and high power quality. The proper operation of these types of power converters requires special control, modulation methods, and capacitor voltage regulation techniques. Both developing capacitor voltage regulation methods and addressing their associated issues with such fall within the primary focus of this dissertation. In this dissertation an investigation was conducted on the capacitor voltage regulation constraints in cascaded H-bridge multilevel converters with a staircase output voltage waveform. In the proposed method, the harmonic elimination technique is used to determine the switching angles. …

Characterization Of Soil Variability For Reliability-Based Design, Sitenikechukwu Onyejekwe

Doctoral Dissertations

"A very carefully planned Missouri-wide field exploration and laboratory investigation program, with a focus on fine-grained soils, was executed with the aim of characterizing the variability of geotechnical parameters statistically with a view to increasing the use of reliability-based design (RBD) among geotechnical engineers. Geotechnical parameters were characterized in terms of both their first and second statistical moments and their coefficient of variation (COV). Their probability distributions and their scale of fluctuation, θ, were also determined. Correlations between difficult-to-obtain parameters and more easily-obtained parameters were developed and the degree of fit of study data to published empirical correlations was investigated. …

Densification And Thermal Properties Of Zirconium Diboride Based Ceramics, Matthew Joseph Thompson

Doctoral Dissertations

"The research presented in this dissertation focuses on the processing and thermomechanical properties of ZrB₂ based ceramics. The overall goal was to improve the understanding of thermal and mechanical properties based on processing conditions and additives to ZrB₂. To achieve this, the relationships between the thermal and mechanical properties were analyzed for ZrB₂ ceramics that were densified by different methods, varying amounts of carbon, B₄C, or TiB₂ additions. Four main areas were investigated in this dissertation. The first showed that decreased processing times, regardless of densification method, improved mechanical strength to >500 MPa. This study also revealed that lower oxygen …

Free-Radical Maleation Of Poly(Butylene Adipate-Co-Terephthalate) In Supercritical Carbon Dioxide And Its Effect On The Percolation And Deformation Mechanism Of Layered Silicate Nanocomposites, Alexandria Niemoeller

Doctoral Dissertations

The utilization of compostable polymers such as poly(butylene adipate-co-terephthalate) (PBAT) in single-use packaging applications can mitigate the water, solvents, and energy required for processing plastic waste. PBAT exhibits exceptional elongational properties, but its moderate water vapor permeability and low tensile modulus limit the applications in which PBAT can be employed. In this work, PBAT nanocomposites were produced at various loadings of organically-modified montmorillonite. The secondary structure of nanoparticles formed within the PBAT matrix was evident in the terminal region of the linear viscoelastic response under oscillatory shear, and a percolation threshold was determined to occur at 3.88% clay by weight. …

Characterization Of Expanded Polystyrene (Eps) And Cohesive Soil Mixtures, Nicholas Thomas Rocco

Doctoral Dissertations

"Soils modified with expanded polystyrene (EPS) particulates could be used as lightweight fill in a variety of installations including slopes for improved stability, embankments over compressible soils, and to reduce earth pressures next to structures. The addition of low density EPS particulates into soil has a large effect on the mass and volumetric characteristics of these mixtures and their influence on mechanical properties is scarce in the literature. A laboratory characterization program using clay mixed with EPS particulates was conducted for different dosages of EPS. Soils were modified with up to 1.5% EPS by mass, which corresponds to approximately 45% …

An Improved Dipole-Moment Model Based On Near-Field Scanning For Characterizing Near-Field Coupling And Far-Field Radiation From An Ic, Zhenwei Yu

Doctoral Dissertations

"Radio Frequency Interference (RFI) problems are critical issues in wireless platform design. The accurate noise model of integrated circuits (ICs) is needed to help designers to diagnose and predict RFI problems. In this dissertation, an improved IC radiated emission model based on near-field measurements is proposed. The regularization technique and the truncated SVD method are employed together with the least square method to calculate the dipole moments from the near-field data. This dipole model has clear physical meaning: the electric and magnetic dipoles represent the voltage and the current in the circuit, respectively. One application of this dipole model is …

Thermal Properties Of Spinel Based Solid Solutions, Kelley R. Wilkerson

Doctoral Dissertations

"Solid solution formation in spinel based systems proved to be a viable approach to decreasing thermal conductivity. Samples with systematically varied additions of MgGa₂O₄ to MgAl₂O₄ were prepared and thermal diffusivity was measured using the laser ash technique. Additionally, heat capacity was measured using differential scanning calorimetry and modeled for the MgAl₂O₄-MgGa₂O₄ system. At 200⁰C thermal conductivity decreased 24% with a 5 mol% addition of MgGa₂O₄ to the system. The solid solution continued to decrease the thermal conductivity by 13% up to 1000⁰C with 5 mol% addition. The decrease in thermal conductivity ultimately resulted in a decrease in heat flux …

Stroke-Related Changes In Neuromuscular Fatigue Of The Hip Flexors And Functional Implications, Allison S. Hyngstrom, Tanya Onushko, Robert Heitz, Anthony Rutkowski, Sandra K. Hunter, Brian D. Schmit

Biomedical Engineering Faculty Research and Publications

Objective: The aim of this study was to compare stroke-related changes in hip flexor neuromuscular fatigue of the paretic leg during a sustained isometric submaximal contraction with those of the nonparetic leg and controls and to correlate fatigue with clinical measures of function.

Design: Hip torques were measured during a fatiguing hip flexion contraction at 20% of the hip flexion maximal voluntary contraction in the paretic and nonparetic legs of 13 people with chronic stroke and 10 age-matched controls. In addition, the participants with stroke performed a fatiguing contraction of the paretic leg at the absolute torque equivalent to 20% …

Segmental Kinematic Assessment Of Pediatric Pes Planovalgus With Radiographic Skeletal Indexing, Katherine A. Konop, Jason T. Long, Joseph Krzak, Adam Graf, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Long-Term Follow Up Of Van Nes Rotationplasty For Proximal Focal Femoral Deficiency, Haluk Altiok, Jeffrey D. Ackman, Ann Flanagan, Mary Peer, Adam Graf, Joseph Krzak, Sahar Hassani, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Proximal focal femoral deficiency (PFFD) is a congenital anomaly that presents challenges for orthopaedic and prosthetic management. The Van Nes rotationplasty is one treatment in which the extremity is surgically rotated to utilize the ankle and foot as a functional knee joint in a prosthesis. The purpose of this study is to determine the long-term functional and quality of life (QOL) outcomes for individuals who have undergone rotationplasty surgery for congenital PFFD compared to age and gender matched controls.

Including Aortic Valve Morphology In Computational Fluid Dynamics Simulations: Initial Findings And Application To Aortic Coarctation, David C. Wendell, Margaret M. Samyn, Joseph Richard Cava, Laura M. Ellwein, Mary M. Krolikowski, Kimberly L. Gandy, Andrew N. Pelech, Shawn C. Shadden, John F. Ladisa

Biomedical Engineering Faculty Research and Publications

Computational fluid dynamics (CFD) simulations quantifying thoracic aortic flow patterns have not included disturbances from the aortic valve (AoV). 80% of patients with aortic coarctation (CoA) have a bicuspid aortic valve (BAV) which may cause adverse flow patterns contributing to morbidity. Our objectives were to develop a method to account for the AoV in CFD simulations, and quantify its impact on local hemodynamics. The method developed facilitates segmentation of the AoV, spatiotemporal interpolation of segments, and anatomic positioning of segments at the CFD model inlet. The AoV was included in CFD model examples of a normal (tricuspid AoV) and a …

Long-Term Follow Up Of Van Nes Rotationplasty For Congenital Proximal Focal Femoral Deficiency [Proceedings], Haluk Altiok, Jeffrey D. Ackman, Ann Flanagan, Mary Peer, Adam Graf, Joseph Krzak, Sahar Hassani, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

INTRODUCTION: Proximal focal femoral deficiency (PFFD) is a congenital anomaly that presents challenges for orthopaedic and prosthetic management. The Van Nes rotationplasty is one treatment in which the extremity is surgically rotated to utilize the ankle and foot as a functional knee joint in a prosthesis. The purpose of this study is to determine the long-term functional and quality of life (QOL) outcomes for individuals who have undergone rotationplasty surgery for congenital PFFD compared to age and gender matched controls.

METHODS: This prospective study had 12 prosthetic participants (PFFD Group: 8 M, 4F, age range 16-57 years) average 31.6±13.5 years …

Multisegmental Foot And Ankle Motion Analysis After Hallux Valgus Surgery, Karl Canseco, Jason T. Long, Thomas Smedberg, Sergey Tarima, Richard Marks, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Background: Gait changes in patients with hallux valgus, including altered kinematic and temporal-spatial parameters, have been documented in the literature. Although operative treatment can yield favorable clinical and radiographic results, restoration of normal gait in this population remains unclear. Segmental kinematic changes within the foot and ankle during ambulation after operative correction of hallux valgus have not been reported. The aim of this study was to analyze changes in multisegmental foot and ankle kinematics in patients who underwent operative correction of hallux valgus. Methods: A 15-camera Vicon Motion Analysis System was used to evaluate 24 feet in 19 patients with …

An Investigation On In-Process Spc Sampling Frequency For Shaft Bearing Turning Process, Jiaxu Chu

Dissertations and Theses @ UNI

The machining processes have the uniqueness of discrete production and flexible scheduling as cellular manufacturing design. To ensure the quality of machining products, control charts for Statistical Process Control (SPC) has been implemented in the company to monitor the machining process. Sampling is an essential part of data collection for SPC control charts and sampling should be done for machining processes becomes an issue in the company.

This study focused on the investigation of SPC sampling frequencies for shaft bearing turning process using the technique of Average Production Length (APL). The purpose of the study was to identify the SPC …

The Integration Of Wind Energy In The Electrical Grid During The Contingencies, Islam Ali

Dissertations and Theses @ UNI

As wind energy expansion develops, there are also many problems and challenges to connect the wind farms to the grid. There are many different interactions during the connection like the voltage flicker, harmonics, transient, short circuit current, frequency, and safety protection. Those problems may affect the performance of the grid and may cause serious problems. This study investigates the grid-connection problems for the wind turbines and offers appropriate solutions. This study provides a simulation for the power system during the faults. The electrical grid in the simulation contains generators and wind turbines which are connected to the grid. It also …

Modeling And Analysis Of Grid-Connected Solar-Wind Hybrid Power System, Sultan Altamimi

Dissertations and Theses @ UNI

Renewable energies are considered to be a significant part of the energy mix to assist the existing electricity demand and the future of electrical generation. Electrical power simulation software is increasingly being used to answer and determine the source of potential problems in the actual power system. To have a better understanding of an electrical power system, it is essential to validate all the components through simulation within an environment that allows accurate modeling of all power system components. This research presents modeling and analysis of an actual grid-connected solar-wind hybrid system at University of Northern Iowa campus in Cedar …

Robotic Manufacturing Cell: An Analysis Of Variables Affecting Performance, Elvis Alicic

Dissertations and Theses @ UNI

Analyzing the performance of manufacturing cells is a well established concept. The justification for conducting thorough analyses of manufacturing cells comes from the known advantages it can provide, including performance improvement and production planning improvement, both current and future. This study focuses on assessing the variables affecting performance of a robotic manufacturing cell through the measure of throughput. Initially, simulation modeling is utilized to model an existing robotic cell and compare the output to actual production output from the same cell. Additionally, general regression modeling is employed to analyze the following variables and their effect on throughput: machine downtime, off-plan …

Leadership Distinctions : The Impact Of Leadership On Teachers Of Second Chance Reading, Rebecca Sue Williams

Dissertations and Theses @ UNI

Second Chance Reading (SCR), an instructional framework that targets and supports struggling adolescent readers and determined to be a sound and viably researched framework, can assist teachers in building and supporting proficient and lifelong learners when implemented as intended. This study examined educators from five unique communities who recently implemented the program. Four key questions guided the research and became the focus during semi-structured purposive interviews. (1) What was the relationship between Second Chance Reading teachers and principal leadership? (2) What leadership qualities were necessary to support Second Chance Reading teachers? (3) What barriers were preventing teachers from accomplishing their …

Incorporating The Delphi Technique To Investigate Renewable Energy Technology Transfer In Saudi Arabia, Nasir K. Al-Otaibi

Dissertations and Theses @ UNI

Saudi Arabia is a major oil-producing nation facing a rapidly-growing population, high unemployment, climate change, and the depletion of its natural resources, potentially including its oil supply. Technology transfer is regarded as a means to diversify countries' economies beyond their natural resources. This dissertation examined the opportunities and barriers to utilizing technology transfer successfully to build renewable energy resources in Saudi Arabia to diversify the economy beyond oil production. Examples of other developing countries that have successfully used technology transfer to transform their economies are explored, including Japan, Malayasia, and the United Arab Emirates. Brazil is presented as a detailed …

Externship Demographics Across Two Decades With Lessons For Future Surveys, J.P. "Sandy" Ogilvy, Sudeb Basu

Scholarly Articles

Sudeb Basu (J.D., Catholic University, 2011) and Professor J.P. “Sandy” Ogilvy (Catholic University) report on the results of a 2007-2009 national survey of externship programs at American law schools and compare many of the data points to previous surveys of externship programs, the 2007-2008 CSALE survey, and some ABA/LSAC data, to chart the growth and increasing sophistication and complexity of the pedagogy associated with legal externships. Some of the data discussed include limits on the number of externship credits or externship courses, student involvement in externships, the distribution of credits awarded for externship courses, the average number of hours of …

Family Law's Challenge To Religious Liberty, Raymond C. O'Brien

Scholarly Articles

This Article argues that challenges made to family law structures have provoked a significant reaction from persons and religious organizations advocating a distinctive worldview based on religious and historical values. Additionally, as family law changes from being a product of a religioushistorical worldview to being a product of private-ordering, the religious liberty of worldview adherents has been challenged. The struggle is apparent in the debates during the 2012 presidential election and is evidenced in government mandates that include, among other requirements, that employersincluding religious organizations-provide insurance coverage for employees that include contraception. Although many aspects of family law have been …

The Technological Edge, Elizabeth I. Winston

Scholarly Articles

To grant a patent to natural phenomena hinders innovation, taking back from the public that which the public has a right to possess. To deny a patent to man’s manufacture undercuts the fundamental bargain of the patent system. All inventions, at their core, may be deemed natural, rendering it difficult to distinguish between man’s manufacture and natural phenomena. Determining whether the innovative aspect of the product is a technological one, rather than a natural one, can clarify whether the patent grant promotes the progress of science and the useful arts. The higher the level of skill in the art required …