Digital Commons Network^™

A Model Based Iterative Reconstruction Approach To Tunable Diode Laser Absorption Tomography, Zeeshan Nadir

Open Access Dissertations

Tunable diode laser absorption tomography (TDLAT) has emerged as a popular nonintrusive technique for simultaneous sensing of gas concentration and temperature. The gas concentration and temperature is computed by making light absorbance measurements using tunable diode lasers. Major challenges of TDLAT imaging include a highly nonlinear measurement process and availability of only a few light absorbance measurements. Therefore, TDLAT imaging of concentration and temperature is an ill-posed, nonlinear inverse problem. Conventional approaches to TDLAT primarily consist of making restrictive assumptions about the gas flow to simplify the problem.

In this thesis, we study the problem of reconstruction of TDLAT measurements …

Electronics And Optoelectronics Devices From Low-Dimensional Systems, Yuqi Zhu

Open Access Dissertations

The notion of low dimensionality becomes more than a pure mathematical ideal, as scaling of modern electronics reaches a state of the art in which electrons are strongly confined at the interface between silicon and the gate oxides in MOSFETs. Moreover, the improvement of material synthesis in the last two decades gives rise to many fascinating materials, in which the electronic states are confined at least for one dimension, like quantum dots (QD) for 0 dimension (0D), carbon nanotubes (CNT) for 1 dimension (1D), graphene and transitional metal dichalcogenides (TMD) as 2 dimensions (2D). In these materials, quantum confinement due …

Towards Predictor Adaptive Robust Control And Inference Of Cyber-Physical Systems With Applications To Aerospace Systems, Jayaprakash “Suraj” Nandiganahalli

Open Access Dissertations

The simultaneous presence of factors such as uncertain plant parameters (e.g., inertia variations, change of damping coefficient), time-varying disturbances (e.g., imprecise mathematical models, uncertain nonlinearities), input delay (e.g., due to transport phenomenon, computation latencies, communication lags), and inaccessibility of the plant states of an nth− order dynamical system present a challenge to the formal control design and to its closed loop stability and performance guarantees. It is well-known that input delays can cause negative phase shifts, limiting the control bandwidth which when coupled with system uncertainties can potentially shift the system into an unstable region of operation. This is especially …

Quantifying The Relations Among Neurophysiological Responses, Dimensional Psychopathology, And Personality Traits., Takakuni Suzuki

Open Access Dissertations

The Research Domain Criteria (RDoC) model, one of the transdiagnostic dimensional models of psychopathology proposed by the National Institute of Mental Health, emphasizes the integration of basic biological science into clinical research. The event-related negativity (ERN), a deflection in electroencephalogram after making an error, is a promising neurophysiological indicator for such endeavor. However, RDoC model posits that ERN is related to three of the five broad dimensions without any indication of how ERN relates differently across the dimensions. Recent research indicate that ERNs elicited from different tasks do not elicit the exact same ERNs. Therefore, constructing theoretically guided tasks and …

Divide And Recombine For Large And Complex Data: Model Likelihood Functions Using Mcmc And Trmm Big Data Analysis, Qi Liu

Open Access Dissertations

Divide & Recombine (D&R) is a powerful and practical statistical framework for the analysis of large and complex data. In D&R, big data are divided into subsets, each analytic method is applied to subsets with no communication among subsets, and the outputs are recombined to form a result of the analytic method for the entire data. This enables deep analysis and practical computational performance. The aim of this thesis is to provide an innovative D&R procedure to model likelihood of the generalized linear model for large data sets using Markov chain Monte Carlo (MCMC) methods and to present an analysis …

Experimental Study Of A Transcritical Thermoacoustic Device, Dayle N. Alexander

Open Access Theses

A prototype transcritical thermoacoustic engine has been constructed and tested, yielding thermoacoustic results. Three different thermoacoustic “stack” designs have been evaluated in the present study. All three show damped acoustic oscillations as a temperature gradient is produced along the stack and a non-linear perturbation is induced. Spontaneously instabilities at much lower frequency were observed in the device with one of the “stacks”. These instabilities grew to a limit cycle amplitude that was maintained until heat was removed. Data are presented for both types of instabilities over a range of operating conditions.

Demonstrator For Selectively Compliant Morphing Systems With Multi-Stable Structures, David M. Boston

Open Access Theses

The field of morphing wings presents significant potential for increasing the efficiency of aircraft. Conventional designs used in the industry limit the adaptability of aerodynamic surfaces to address an engineering trade-off between load-carrying and compliance. This same trade-off remains a factor in morphing wings, which must also balance weight considerations while attempting to remain competitive with conventional designs. The current state-of-the-art in morphing wings is briefly described in this work. This is followed by an investigation into a new application of the principle of selective stiffness, by which local changes in stiffness may be applied to affect the global structural …

The Approach To Ridge Regression For Big Data: An Examination, Wan-Chih Chiang

Open Access Theses

Ridge regression is a technical method to deal with highly correlated data when using regression model for analysis. Like other traditional techniques, one common limitation happens when the data size is bigger than the storage capacity of the memory or taking most of the memory storage. The analysis can’t complete because of memory error, either happening in loading the data into the memory or during the calculation step. Sampling or extending the memory storage capacity may be two possible solutions to avoid the problem. However, it probably brings unknown bias when the population is enormous or high costs in establishing …

Detection And Management Of Diabetes Mellitus (Type -Ii), Ridhi Deo

Open Access Theses

Diabetes is a life threatening disease. Diabetes is also hereditary and its incidence depends on factors pertaining to the health, lifestyle and family background of an individual. Gestational Diabetes Mellitus (GDM) is a special case in diabetes which occurs only during pregnancy. The aim of the author’s thesis is to mathematically model the risk factors for diabetes (type -2). The factors are modeled to predict if an individual will have diabetes. The model is aimed at being beneficial to patients so that they can determine if their current lifestyle habits are healthy. The purpose of the thesis is to explore …

Truck-Drone Hybrid Delivery Routing: Payload-Energy Dependency And No Fly Zones, Ho Young Jeong

Open Access Theses

The truck-drone hybrid delivery system uses a truck as a station for drones in addition to its delivery function and is getting attention because the strengths of these individual vehicles can be selectively and synergistically exploited. In this study, the previous vehicle routing models are extended to the hybrid delivery systems by taking into account two important practical issues: the effect of parcel weight on drone energy consumption and prohibited flying areas. The flight range of the drones is heavily susceptible to the loaded weight due to the limited battery life. Drones are also not allowed to fly over sensitive …

Fatigue Damage Modeling Approach Based On Moving Power Spectrum Density, Zhui Li

Open Access Theses

Fatigue damage estimation has long been treated as an important area of research in order to design machines and structures dependably during their entire lifetime. The durability of engineering components and structures under expected vibrational environment must be assessed to meet design requirements for the reliability and safety in the service life. In past decades, fatigue damage estimation approaches in both time domain and frequency domain have been developed to simulate the operational life of the structures under severe vibrations.

Current frequency fatigue prediction methods for accelerated vibration loading conditions, however, are based on stationary Power Spectral Density (PSD) inputs. …

Development Of High Frequency Virtual Thermocouples, Shengqi Lu

Open Access Theses

This thesis is dedicated in development of temperature measurement technique based on K-type thermocouple. Assessment of thermocouple response is conducted with the assistance of complete conjugate heat transfer simulations. Numerical results are acquired from an instantaneous solution of heat transfer between the interface of fluid and solid. Enormous CFD cases are analyzed with variations of gas temperature, gas pressure and wall temperature for a series of thermocouples at 6µm,12µm,25µm, and 50µm. The second-order transfer function is used to characterize the properties of response curves in discrete-time domain. Effect of the different parameters to thermocouple response is concluded in terms of …

Low-Cost Grain Moisture Meter System Networked To Smartphones, Marisol Pantoja Otero

Open Access Theses

Accurate moisture content measurement is one of the key quality factors listed in grain trade. It is important in determining whether a crop has been dried properly for safe storage and marketing, and it is used by buyers and sellers of grain to estimate the value of the commodity. Unfortunately, many farmers and grain originators in developing countries cannot afford to buy moisture meters and utilize them to routinely determine whether their crops are dried for safe storage, and thus incur huge losses along the value chain. Additionally, farmers are at a disadvantage in trading to high-ended markets, which have …

Raman Thermometric Method Development, Colby W. Raymond

Open Access Theses

Water has an identifiable Raman feature between 3000-4000 cm-1 that can act as a probe for its environment. Generally, on addition of hydrophobic solutes into water, the OH stretching mode is perturbed enough to show changes that indicate a disruption in the hydrogen bonding network. That stretching mode is also highly temperature dependent, exhibiting spectral changes at low temperatures, around 3000-3200 cm-1 & high temperatures, around 3600 cm-1. These regions respectively indicate tetrahedral order or disordered state enhancement. The state enhancement is respectively from either an increase or a breakdown of the rigid hydrogen bonding network. Previous methods of water …

In-Silico Tensile Testing Of Additively Manufactured Short Fiber Composite, Miguel A. Ramirez

Open Access Theses

The extrusion deposition additive manufacturing process produces a short fiber composite material wherein the details of its microstructure directly depend on the manufacturing process parameters. Performance characterization of these materials may become an expensive and laborious proposition if many processing changes are made. The framework for virtually characterizing the mechanical behavior of additively manufactured short fiber composites has been created based on the homogenization methods utilized in multiscale analyses. Experimental quantification of the microstructure of a printed carbon fiber reinforced polycarbonate with 20% fiber weight fraction was performed. The statistical data obtained from the microstructure were used as input parameters …

Exploring The Knowledge, Skills, And Abilities Of Data Science Professionals, Corey S. Seliger

Open Access Theses

The feld of data science is growing at break-neck speeds. More industries are looking towards data science professionals to fnd, compile, explore, and model data from numerous areas of interest. Currently, there are over 130,000 data science positions open. Professional training and institutions of higher education are unable to train enough individuals to place into these positions. Initial research in this space has started reviewing some of the data in this space, including determining the knowledge, skills, and abilities (KSAs) employers seek in data science candidates and what institutions are providing in the means of preparation in this space. With …

An Experimental Diminished Reality Implementation For Augmented Reality Furniture Shopping Applications, Zhengda Shi

Open Access Theses

This study focuses on implementation and user satisfaction assessment of a newly designed diminished reality method. To improve customers’ experience in previewing the result of replacing large furniture at home, an experimental method which covers a background rendering overlay cube on the target furniture was designed. An application implementing this method was developed, and a user experience survey was conducted. We were expecting our method would help customers find appropriate furniture and make decisions, but the result showed the reversed effect. However, some conclusions of this study can be useful for other future research.

A Multi-Objective Design Optimization Approach For Suas Fleet Design & Allocation In Meteorological Sampling Operations, Brandon E. Sells

Open Access Theses

Many potential small Unmanned Aerial Systems (sUAS) applications require or would benefit from deploying a fleet of aircraft to perform a mission. Fleet operations present advantages to maximize mission success by using additional sUAS; however, an additional advantage exists in the ability to design a bespoke sUAS and capitalize on the innovation in rapid prototyping and collaborative control. If this fleet includes new, yet-to-be-designed sUAS, the problem of both designing the new sUAS and allocating the fleet becomes a challenging optimization problem. Starting from promising work in similar applications, this work will investigate how a decomposition approach will allow a …

Gas Rarefaction Effects In Nonlinear Acoustic Wave Steepening, Shubham Thirani

Open Access Theses

A numerical investigation of the effects of gas rarefaction on the steepening of planar nonlinear acoustic waves has been presented here. To this end, a problem setup consisting of a piston-tube assembly with adiabatic walls and the piston oscillating at the fundamental harmonic frequency of the tube was considered. The Knudsen number, which is a metric of the degree of rarefaction of the gas, considered for the assembly ranges from 0.1 to 10−5 with decrements of an order of magnitude between successive cases. The computational setup consists of numerical schemes based on the Bhatnagar-Gross-Krook (BGK) model for the Boltzmann equation …

Landscape Transitions And Socioeconomic Drivers As Predictors Of Fire Frequency, Mariam Gabriela Valladeres Castellanos

Open Access Theses

Fire prediction systems rely on meteorological descriptors and fuel characteristics to determine fire risk at national scales. However, at a regional scale, anthropogenic dynamics play an important role in determining fire ignition, as well as spatial and temporal distributions. Under an increasing fire activity scenario projected for the next century, Mediterranean ecosystems are particularly fragile regions. Fire variability driven by human stressors is the main threat to the native vegetation and human populations in these regions. The inclusion of anthropogenic indicators on fire prediction systems, especially within Mediterranean ecosystems, is key to developing accurate predictions and effective fire management efforts. …

Investigating The Effects Of Cobalt And Nickel Mixtures On Tungsten Toxicity In Zebrafish (Danio Rerio), Ola Wasel

Open Access Theses

Tungsten (W) is a refractory metal that is used in a wide range of applications. Initially perceived as immobile in the environment, tungsten replaced lead and uranium in munition and military applications. Recent studies report movement and detection of tungsten in soil and potable water sources increasing the risk of human exposure. In addition, experimental research studies observed adverse health effects associated with exposure to tungsten alloy, raising concerns on tungsten toxicity with questions surrounding the safety of exposure to tungsten alone or in mixtures with other metals. Tungsten is commonly used as an alloy with nickel (Ni) and cobalt …

Pre-Service Teachers' Understanding Of Geometric Reflections In Terms Of Motion And Mapping View, Murat Akarsu

Open Access Dissertations

In this manuscript, I describe a study of pre-service secondary mathematics teachers’ (PTs) understanding of geometric reflection in terms of a motion and a mapping views. PTs often have a motion view of geometric reflection based on their understanding of reflection line, domain, and plane. A motion view is a preliminary perspective developed prior to the construction of a mapping view. PTs need a mapping view of geometric reflection, and to be conscious of sub-concepts of a mapping view involved reflection line, domain, and plane. However, there is no clear evidence documenting how a learner’s motion view evolves to produce …

She Is A Computer Scientist: A Quantitative Comparison Between The Effectiveness Of Game Design Studios And Robotics At Enhancing Women's Learning Of, Self-Efficacy In, Attitudes Toward, And Domain Identification With Computer Science, Ali Nazil Alshammari

Open Access Dissertations

The underrepresentation of women in computer science is a serious issue with ramifications that affect not only women working in the field, but also the field at large and the national economy. While the problem is attributed to several interconnected causes, such as computer knowledge, experience, and familiarity; they do not tell the entire story, nor do they point to a global trend. Studies indicate that these factors did not stop the computer science field from achieving a balanced male-female ratio in non-western countries. Since no single factor can be attributed as the primary cause of this complicated problem, and …

An Overall Policy Decision-Support System For Educational Facilities Management: An Agent-Based Approach, Haya Bader Albader

Open Access Dissertations

Although K-12 public school facilities infrastructure investments are second only to highways, schools continue to suffer from an approximately $38 billion annual funding gap. Massive reductions in funding are forcing school districts to make tough decisions to optimize maintenance expenditures. Over the last three decades, a huge body of research has determined that the condition of school facilities do affect student health and performance, and some have further demonstrated that schools are overwhelmed by deteriorating facilities that threaten the health, safety, and learning opportunities of students. The currently available educational facility management approaches oversee the influence of the complex and …

Modeling Of Bearing Dynamics Using Combined Efem-Dem Method, Lijun Cao

Open Access Dissertations

The objective of this investigation was to develop a 3D dynamic model to study the rotorbearing- housing system. To achieve the objective, an existing dynamic bearing model (DBM) was combined with a flexible bearing housing model and a flexible rotor model. The DBM is based on the discrete element method (DEM), in which all bearing components are assumed to be rigid and have six degrees of freedom. The 3D explicit finite element method (EFEM) was used to develop the flexible housing and rotor models. To couple the bearing outer race (OR) with housing, a novel algorithm was developed to detect …

Assessment Of Urbanization Impacts On Surface Runoff And Effects Of Green Infrastructure On Hydrology And Water Quality, Jingqiu Chen

Open Access Dissertations

Urbanization is one of the most important anthropogenic modifications of the global environment. It has significant impacts on hydrologic processes and water quantity and quality. Research related to urbanization impacts on surface runoff has focused on changes up to the watershed scale. However, quantitative assessment at a national scale is scarce. Parallel to urbanization impacts, climate is also one of the greatest challenges facing humanity today and its effects are already being felt from strengthened storms and rising sea levels to changing temperature and weather patterns. The adverse impacts of urbanization and climate can converge in synergistic ways, which may …

Modeling And Simulation Of Blood Flow Past The Distal Anastomosis Of The Arteriovenous Graft For Hemodialysis, Zengding Bai

Open Access Dissertations

Hemodialysis is a common treatment for ESRD patients to manage their chronic renal failure while awaiting kidney transplant. Arteriovenous graft is a major vascular access for hemodialysis but often fails due to the thrombosis close to the anastomosis. Most of existing computational models employ an unrealistic rigid model assuming the vein and graft are rigid. And some of the existing results are inconsistent in characterizing the flow and force fields. We introduce a new three-dimensional computational model that incorporates the vein and graft deformability. The new model is based on the lattice Boltzmann-immersed boundary (LB-IB) framework for handling the fluid-flexible-structure …

Computational Methods For Matrix/Tensor Factorization And Deep Learning Image Denoising, Joon Hee Choi

Open Access Dissertations

Feature learning is a technique to automatically extract features from raw data. It is widely used in areas such as computer vision, image processing, data mining and natural language processing. In this thesis, we are interested in the computational aspects of feature learning. We focus on rank matrix and tensor factorization and deep neural network models for image denoising.

With respect to matrix and tensor factorization, we first present a technique to speed up alternating least squares (ALS) and gradient descent (GD) − two commonly used strategies for tensor factorization. We introduce an efficient, scalable and distributed algorithm that addresses …

Metaethical Mooreanism, Jonathan Fuqua

Open Access Dissertations

This dissertation is an attempt to apply the Moorean response to radical skepticism to moral skepticism. In a nutshell, I argue as follows. Assume that the following Moorean response to, say, BIV skepticism (the worry that I don’t know I’m not a brain in a vat) is roughly correct: “I know I have hands, so I’m not a BIV; any argument to the contrary must have a flaw somewhere.” If so, then such a Moorean should respond as follows to moral skepticism: “I know that recreational genocide is wrong, so it’s false that there are no moral facts, and that …

Gnss/Ins-Assisted Multi-Camera Mobile Mapping: System Architecture, Modeling, Calibration, And Enhanced Navigation, Magdy Elbahnasawy

Open Access Dissertations

To date, due to some financial and technical constraints, camera-based mobile mapping systems with GNSS/INS unit onboard the platform are still the optimal option for most mapping applications. Therefore, a great deal of research has been conducted on developing an operational GNSS/INS-assisted single/multi-camera mapping system. However, to satisfy the needs of various mapping applications, there are still challenges that have to be addressed. Such challenges start with the selection and integration framework of sensors (cameras and GNSS/INS units) onboard different types of mapping platforms (i.e., UAV and wheel-based platforms). Another challenge is modeling and calibrating the GNSS/INS-assisted single/multi-camera mapping systems. …