Digital Commons Network^™

In Vitro Multi-Scale Patient-Specific Modeling Of Hemodynamics In Stage 1 Norwood Palliation For The Treatment Of Single Ventricle Heart Disease, Tianqi Hang

All Dissertations

Hypoplastic left heart syndrome (HLHS) is a congenital heart defect in which the left ventricle is severely underdeveloped. The Norwood procedure is the first stage procedure to make an unrestrictive systemic blood flow and at the same time balance it with the pulmonary flow. This is done by constructing a neo-aorta using the pulmonary artery root and the autologous aorta, and then installing a shunt to the pulmonary artery. Variations of the Norwood surgery include the modified Blalock-Taussig (mBT) shunt, which diverts blood from the innominate artery to the pulmonary artery (PA), and the Right Ventricle Shunt (RVS), which diverts …

Nursing Interruption Dynamics: The Impact Of Work System Factors, Yushi Yang

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Interruptions occur frequently in healthcare work systems. Hands-free Communication Devices (HCDs) were implemented in healthcare work systems to support the interruption process. However, from a sociotechnical systems perspective, HCDs may introduce new complications and unintended consequences to the work system. Research gaps exist in investigating the complexity of HCD interruptions in the real-world context. This dissertation aims to understand HCD interruption dynamics in the nursing work systems, using qualitative research methods. The first study examined the major differences between face-to-face and HCD-mediated interruptions, based on 30 hours of field observations in the acute care setting. Three major differences included: (1) …

Electromechanical Modeling Of A Honeycomb Core Integrated Vibration Energy Converter With Increased Specific Power For Energy Harvesting Applications, Nataraj Chandrasekharan

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Innovation in integrated circuit technology along with improved manufacturing processes has resulted in considerable reduction in power consumption of electromechanical devices. Majority of these devices are currently powered by batteries. However, the issues posed by batteries, including the need for frequent battery recharge/replacement has resulted in a compelling need for alternate energy to achieve self-sufficient device operation or to supplement battery power. Vibration based energy harvesting methods through piezoelectric transduction provides with a promising potential towards replacing or supplementing battery power source. However, current piezoelectric energy harvesters generate low specific power (power-to-weight ratio) when compared to batteries that the harvesters …

A Study On General Assembly Line Balancing Modeling Methods And Techniques, Bryan Pearce

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The borders of the assembly line balancing problem, as classically drawn, are as clear as any other operations research topic in production planning, with well-defined sets of assumptions, parameters, and objective functions. In application, however, these borders are frequently transgressed. Many of these deviations are internal to the assembly line balancing problem itself, arising from any of a wide array of physical or technological features in modern assembly lines. Other issues are founded in the tight coupling of assembly line balancing with external production planning and management problems, as assembly lines are at the intersection of multiple related problems in …

Robust Model Development For Evaluation Of Existing Structures, Saurabh Prabhu

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In the context of scientific computing, validation aims to determine the worthiness of a model in supporting critical decision making. This determination must occur given the imperfections in the mathematical representation resulting from the unavoidable idealizations of physics phenomena. Uncertainty in parameter values furthers the validation problems due to the inevitable lack of information about material properties, boundary conditions, loads, etc. which must be taken into account in making predictions about structural response. The determination of worthiness then becomes assessing whether an unavoidably imperfect mathematical model, subjected to poorly known input parameters, can predict sufficiently well in its intended purpose. …

Configuration Management In Manufacturing And Assembly: Case Study And Enabler Development, Keith Phelan

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The overall goal of this research is to improve the product configuration change management process. The increase in the demand for highly customizable products has led to many manufacturers using mass customization to meet the constantly changing demands of a wide consumer base. However, effectively managing the configurations can be difficult, especially in large manufacturers or for complex products with a large number of possible configurations. This is largely due to a combination of the scope of the configuration management system and the difficulty in understanding how changes to one element of a configuration can propagate through the configuration system. …

Practical Robust Geotechnical Design- Methodology And Applications, Sara Khoshnevisan

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This dissertation advances the robust geotechnical design methodology by offering improvements, which makes it more efficient and practical for the design of geotechnical systems. Robust geotechnical design (RGD) methodology seeks an optimal design, which is insensitive to, or robust against, the variation in the uncertain input parameters (called “noise factors”) by only adjusting the easy to control parameters (called “design parameters”). The main goal of robust design is to consider safety, cost and robustness simultaneously. Because the cost and the robustness are conflicting objectives, the multi-objective optimization that considers these two objectives while enforcing the safety constraint yields not a …

Designing Optical Properties In Infrared Glass, Benn Gleason

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Chalcogenide glasses (ChGs) are well-known for their attractive optical properties, such as high refractive index and transparency in across infrared wavelengths. ChGs also possess the ability to compositionally tune properties such as the refractive index, the thermo-optic coefficient, and other non-optical properties. Chalcogenide glasses with compositionally tailored physical and optical properties will provide optical designers with new materials necessary to create novel infrared imaging systems requiring new or expanded functionality. This dissertation has evaluated the relationship between glass composition, the resulting atomic structure, and resulting optical and thermo-optical properties, with specific focus on the infrared refractive index and the thermo-optic …

A Special Protection Scheme Utilizing Trajectory Sensitivity Analysis In Power Transmission, Dan Suriyamongkol

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In recent years, new measurement techniques have provided opportunities to improve the North American Power System observability, control and protection. This dissertation discusses the formulation and design of a special protection scheme based on a novel utilization of trajectory sensitivity techniques with inputs consisting of system state variables and parameters. Trajectory sensitivity analysis (TSA) has been used in previous publications as a method for power system security and stability assessment, and the mathematical formulation of TSA lends itself well to some of the time domain power system simulation techniques. Existing special protection schemes often have limited sets of goals and …

Proportioning And Properties Of Ultra-High Performance Concrete Mixtures For Application In Shear Keys Of Precast Concrete Bridges, Zhengqi Li

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Ultra-high performance concrete (UHPC) is defined as a cementitious based composite material with compressive strengths above 150 MPa, pre-and post-cracking tensile strengths above 5 MPa, and enhanced durability. To achieve desired properties, UHPC is typically produced with low water-cementitious materials (w/cm) ratio (i.e. w/cm < 0.25), high cementitious materials content (i.e. >1000 kg/m3), high quality aggregate, high dosage of high-range water reducing admixture (HRWRA) and reinforcing fibers. UHPC has distinct advantages in applications where narrow formwork and dense reinforcement are inevitable, high compressive strength concrete material is required and the surrounding environment is aggressive. The construction of shear keys in precast bridges is one of the important …

An Investigation Of The Efficiency Of Synergistic Multicultural Teams, Melissa Dorlette Paul

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The current globalized environment has increased the prevalence of multicultural teams in the workplace. While much research has focused on the advantages of such teams, the challenges companies should anticipate when using them has not received as much attention. These difficulties, specifically communication and trust, need to be considered to ensure that the company remains competitive in an economy driven by growing client expectations. In addition, companies often have to meet tight delivery schedules in order to survive, an expectation which adds strain on production teams. Efforts to address these issues have ranged widely, with some researchers suggesting cultural awareness …

Electrospray Deposition Of Chalcogenide Glass Films For Gradient Refractive Index And Quantum Dot Incorporation, Spencer Novak

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Chalcogenide glasses (ChGs) are well-known for their optical properties, making them ideal candidates for emerging applications of mid-infrared microphotonic devices, such as lab-on-a-chip chemical sensing devices, which currently demand additional flexibility in processing and materials available to realize new device designs. Solution-derived processing of ChG films, initially developed in the 1980s by Chern and Lauks, has consisted mainly of spin-coating and offers unique advantages over the more traditional physical vapor deposition techniques. In the present effort, the nanoparticles of interest are luminescent quantum dots (QDs), which can be used as an on-chip source of light for a planar chemical sensing …

Developing Effective Ground And Space-Based Soil Moisture Sensing Techniques For Irrigating Cotton In Coastal Plain Soils, Xin Qiao

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Irrigation scheduling based on soil moisture sensor readings has gained popularity in the past few decades since it can enhance crop yield while saving water. Such method is limited since the representativeness of an individual soil moisture sensor measurement is questionable in a large field with variable soil type and texture. The optimum location of soil moisture sensors needs to be determined within such a production field for effective sensor-based irrigation scheduling. Therefore, the first object of this study was to investigate the optimum sensor location and the number of moisture sensors required for irrigating cotton in coastal plain soils. …

Optimization Of Pyrochlore Catalysts For The Dry Reforming Of Methane, Felipe Polo Garzon

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The conversion of methane into syngas (a mixture of CO and H2), which can be further converted into a variety of chemicals and particularly liquid fuels, is of growing importance given recent increases in methane production world-wide. Furthermore, since using CO2 as the co-feed offers many environmental advantages, dry reforming of methane (DRM, CH4 + CO2 ⇌ 2CO + 2H2) has received renewed attention. In recent years, experimentalists have shown that the Rh-substituted lanthanum zirconate pyrochlore (LRhZ) material is catalytically active for DRM, exhibits long-term thermal stability and resists deactivation; however, previous to this doctoral work, a detailed understanding of …

A Laminated Ring On Elastic Foundation Model With Application To Analysis Of Tire-Road Contact, Chunjian Wang

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A deformable Ring on Elastic Foundation (REF) model has been widely used for modeling rotating structures such as gears, bearings and tires. This dissertation extends the existing work with three main contributions focusing on applications to tires: 1) The elastic foundation is endowed with unilateral stiffness, which leads to a nonlinear deformation dependent stiffness typical of some non-pneumatic tires; 2) The model of the deformable ring is extended from simple Timoshenko rings to a laminated orthotropic ring model, with bending, shear stiffness and extensibility in the internal layer, and transverse stiffness in the external layer; 3) Facilitated by the laminated …

Integrated Coherent Combining Of Angled-Grating Broad-Area Lasers: Design, Fabrication And Characterization, Yunsong Zhao

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In this thesis, we proposed, fabricated and demonstrated the coherent beam combining of angled-grating broad-area lasers. We have obtained the simultaneous coherent beam combining and single transverse mode operation completely on chip without any external phase control/components. Since the single transverse mode is the key to obtain diffraction-limit beam quality and high brightness, the proposed design is a good candidate for high power and high brightness applications. In the proposed coherently combined laser array, we use the angled-grating broad-area laser as the building block and overlap the adjacent emitters at one facet. The overlapped region becomes a 2D coupling region. …

On Subgrid-Scale Physics In The Convective Atmospheric Surface Layer, Khuong Nguyen

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The dynamics of the subgrid-scale (SGS) stress and scalar flux in the convective atmospheric surface layer are studied using field measurements from the Advection Horizontal Array Turbulence Study (AHATS). We extend the array technique previously used to evaluate the SGS velocity and temperature to include measurements of the fluctuating pressure, enabling separation of the resolvable- and subgrid-scale pressure and allowing for the first-ever observations of the pressure covariance terms and the full SGS budgets. Non-dimensional forms of the budget terms are analysed as functions of the surface-layer stability parameter and the ratio of the wavelength of the spectral peak of …

Understanding The Automotive Pedal Usage And Foot Movement Characteristics Of Older Drivers, Yubin Xi

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The purpose of this study was to understand the pedal usage characteristics of older drivers in various driving tasks using an instrumented vehicle. This study stemmed from the prevalence of the pedal application errors (PAEs) and the older drivers’overrepresentation in crashes caused by PAEs.

With the population increasing and becoming older, it is estimated that in 2020 there will be 40 million drivers over the age of 65 in the United States. Compared with their younger counterparts, older drivers are facing declining cognitive and physical abilities, such as impaired vision, slower reaction time and diminishing range of limb motion. Because …

Design Of A Meta-Material With Targeted Nonlinear Deformation Response, Zachary Satterfield

All Theses

The M1 Abrams tank contains track pads consist of a high density rubber. This rubber fails prematurely due to heat buildup caused by the hysteretic nature of elastomers. It is therefore desired to replace this elastomer by a meta-material that has equivalent nonlinear deformation characteristics without this primary failure mode. A meta-material is an artificial material in the form of a periodic structure that exhibits behavior that differs from its constitutive material. After a thorough literature review, topology optimization was found as the only method used to design meta-materials. Further investigation determined topology optimization as an infeasible method to design …

Experimental Investigation Of Heat Leakage And Air Leakage In Domestic Refrigerators, Shervin Shoai Naini

All Theses

The optimization of the energy consumption in household refrigerators should consider the influence of the gasket which determines the heat transfer and air infiltration rate. In this research project, engineering methods are developed to evaluate the heat leakage due to the gasket and air infiltration in domestic refrigerators. In the first study, experimental and numerical approaches are applied to evaluate the gasket heat transfer based on the “Reverse Heat Load Method”. The main objective is to find the effective heat leakage with the dimensions of energy leakage per gasket length per temperature difference (W/m.K). An insulated cubic box with a …

A Robust Data Exchange Framework For Connected Vehicle Technology Supported Dynamic Transit Operations, Yucheng An

All Theses

Transit systems are an integral part of surface transportation systems. A connected vehicle technology (CVT) supported transit system will assist the users to manage trips both dynamically and efficiently. The primary focus of this research is to develop and evaluate the performance of a secure, scalable, and resilient data exchange framework. In the developed data exchange framework, a new data analytics layer, named Transit Cloud, is used to receive data from different sources, and send it to different users for a Dynamic Transit Operations (DTO) application. The DTO application allows the transit users to request trip information and obtain itineraries, …

The Performance Of Quaternary Amplitude Modulation With Quaternary Spreading In The Presence Of Interfering Signals, Allison Manhard

All Theses

Multiple-access digital communications is considered with direct-sequence spread-spectrum (DS-SS) quadrature amplitude modulation and quaternary spreading in each transmission. Each transmitted signal undergoes attenuation and a delay at a receiver in the additive white Gaussian noise channel. The receiver uses coherent demodulation with a correlation detector synchronized to the one of the K received signals so that the K - 1 other transmissions act as interference. The average probability of error at the output of the detector is determined using Monte Carlo simulation and compared with an approximation in which the interference component in each detection statistic is approximated by a …

Decellularized Bovine Nucleus Pulposus As A Biomimetic Scaffold For Intervertebral Disc Regeneration, Christopher Fernandez

All Theses

Low back pain (LBP) is a significant burden with a lifetime prevalence of 84% and estimated expenditures of $85.9 billion.[1,2] Although LBP is multifactorial; it has been shown that LBP can originate from degenerating intervertebral discs (IVDs); a process which initiates in the nucleus pulposus (NP); a hydrated tissue primarily composed of type 2 collagen and proteoglycan. Current therapies for IVD degeneration (IDD) are palliative and merely delay surgical management. While these procedures may relieve pain temporarily, they fail to address the underlying cause of degeneration and make no attempt to regenerate the effected tissue. Additional concerns with the use …

Structural Optimization Using Parametric Programming Method, Krupakaran Ravichandraan

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The Parametric Programming method is investigated to consider its applicability to structural optimization problems. It is used to solve optimization problems that have design variables as implicit functions of some independent input parameter(s). It provides optimal solutions as a parametric function of the input parameter(s) for the entire parameter space of interest. It does not require the detailed discrete optimizations needed at a large number of parameter values as in traditional non-parametric optimization. Parametric programming is widely used in optimal controls, model predictive control, scheduling, process synthesis and material design under uncertainty due to the above mentioned benefits. Its benefits …

Single Particle And Biological Cell Detection By A Radio Frequency Interferometer, Zheng Wang

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This thesis presents a series of studies on single particle and biological cell detection and differentiation by a radio frequency (RF) interferometer system. Several techniques, such as dielectrophoresis (DEP), time domain method and 3D focusing have been illustrated and investigated to demonstrate the capacity of interrogating the electric property of single particle or biological cell by the RF interferometer. Silica particles and live yeast cells are trapped at the sensing area by DEP force and detected by the RF sensor. Solutions of particle mixtures (~4 μm silica and ~10 μm polystyrene) and cell mixtures (viable and non-viable yeast cells, normal …

Improving The Implementation Of Pavement Preservation Strategies In South Carolina, Franklin Reed

All Theses

With compounding budget constraints on infrastructure, cost effective solutions to maintain roadways are becoming increasingly important. Pavement preservation provides a cost effective option to keep the roadway network at an acceptable level. However, pavement preservation is a relatively new concept that many states have not fully implemented successfully. This research supports efforts to improve the pavement preservation practices in the state of South Carolina. It analyzes the current pavement preservation practices in South Carolina as well as other states to identify where improvements could be made. The research also outlines a treatment tracking program for the state of South Carolina …

Design Of A Web Application To Improve The Efficiency Of Crnas., Venkatramanan Chanchapalli Madhavan

All Theses

Physical artifacts such as whiteboards have been successfully used in healthcare facilities to keep track of dynamic changes in information and to manage work schedules. Since these whiteboards are easy- to- use and do not require any technical expertise, they have been easy- to-adopt. Additionally, they act as memory aids for the users by capturing transient information. However, they have their own limitations, the primary ones being the lack of mobility and real-time updates, both of which are crucial in a high consequence environment such as a healthcare facility. These whiteboards are usually kept in a central location with the …

Phasor Measurement Unit Deployment Approach For Maximum Observability Considering Vulnerability Analysis, Jyoti Paudel

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In recent years, there has been growing interest of synchrophasor measurements like Phasor Measurement Units (PMUs) Power systems are now being gradually populated by PMU since they provide significant phasor information for the protection and control of power systems during normal and abnormal situations. There are several applications of PMUs, out of which state estimation is a widely used. To improve the robustness of state estimation, different approaches for placement of PMUs have been studied. This thesis introduces an approach for deployment the PMUs considering its vulnerability. Two different analysis have been considered to solve the problem of locating PMUs …

Characterization Of A Multi-Laminate Angle-Ply Af Patch For Annulus Fibrosus Repair, Ryan Borem

All Theses

Annually, over 5.7 million Americans are diagnosed with two IVD-associated pathologies: IVD herniation (IVDH- a mechanical disruption of the concentric fibrous layers of the annulus fibrosus (AF))) and degeneration (IVDD- a multifactorial process which initiates within the inner gelatinous core (NP), and results in a biochemical degradation of NP tissue), with over 2.7 million requiring surgical inteventions.1,2 Although both underlying pathologies are different, quite often they both lead to a decrease in IVD height, impaired mechanical function, and increased pain and disability. These pain symptoms affect approximately 80% of the adult population during their lifetime with estimated expenditures exceeding $85.9 …

Design And Analysis Of Foundation For Onshore Tall Wind Turbines, Shweta Shrestha

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Wind turbines play a vital role in producing sustainable and clean energy to fulfill the growing energy needs. Energy generated from wind turbines being more sustainable and cost effective, many countries have taken a major step to develop wind turbines with large capacity. There has been a significant reduction in the levelized cost of energy (LCOE) since the 1980’s from the development of larger wind farms and from consistent performance improvements of wind turbine components. The power generation capacity of wind turbines has increased significantly over the years with the use of taller towers. When the tower height increases, the …