Engineering Commons^™

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

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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. …

Synthesis And Characterization Of Oleophobic Fluorinated Polyester Films, Tugba Demir

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The study presented in this dissertation is dedicated to the synthesis and characterization of oleophobic fluorinated polyester films. Specifically, the blending of oleophilic polyethylene terephthalate (PET) with low surface energy materials such as fluorinated polyesters has been used in order to fabricate oleophobic PET films. First, fluorinated polyesters (P(PF-oate-R)) possessing different end-groups (-COOH, -OH and -CF3) are synthesized via polycondensation reaction of isophthaloyl chloride with perfluoro ether alcohols. Then, they are solvent-blended with PET at various concentrations to obtain oleophobic polyester films of different compositions. In addition, the films are annealed to investigate the effect of annealing on surface properties …

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 …

Electrochemical Enhancement Of Butanol Production And Xylose Consumption In Pure And Mixed Culture Fermentations, Jovan Popovic

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The volatility of foreign and domestic petroleum markets has prompted initiatives for the development of alternative liquid energy carriers which have the capacity to accommodate our current transportation infrastructure. Butanol, which has an energy density similar to that of gasoline and can be produced through the fermentation of carbohydrates by solventogenic Clostridia, has been investigated as a supplement or direct replacement to gasoline. However, most butanol fermentations rely on glucose as a feedstock which is in direct competition with our food supply, and this requires the exploration of alternative fermentable substrates. This study investigates the use of electrochemical fermentation modifications …

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. …

A Time-Efficient Strategy For Relay Selection And Link Scheduling In Wireless Communication Networks, Chenxi Qiu

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Despite the unprecedented success and proliferation of wireless communication, sustainable reliability and stability among wireless users are still considered important issues in the underlying link protocols. Existing link-layer protocols, like ARQ [44] or HARQ [57,67] approaches are designed to achieve this goal by discarding a corrupted packet at the receiver and performing one or more retransmissions until the packet is successfully decoded or a maximum number of retransmission attempts is reached. These strategies suffer from degradation of throughput and overall system instability since packets need to be en/decode in every hop, leading to high burden for relay nodes especially when …

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 …

Investigation Into Mechanisms And Mitigation Of Alkali-Silica Reaction In Sustainable Portland Cement Concrete Containing Recycled Glass Materials, Kaveh Afshinnia

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A significant portion of recycled glass from municipal waste streams is not found to be suitable for reuse as cullet in the production of new glass containers, and as a result it is disposed in landfills. One of the appropriate ways to reduce the disposal of waste glass in landfills is by using it in portland cement concrete as an aggregate material and/or supplementary cementitious material to replace portion of portland cement. The high silica content of the soda glass (approximately 70%) can potentially behave as a pozzolanic material when finely ground, which may enhance the mechanical and durability properties …

Effects Of Growth Factor Supplementation And Environmental Conditions On Human Adipose-Derived Stem Cell Differentiation Towards Urothelial Lineage, James Turner

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In recent years, tissue engineering of the bladder has undergone many technological advances. Autologous urothelial cells have been used in animal models and have shown increased performance for ureteral reconstruction compared to unseeded grafts. However, since patients may lack a reliable source of native urothelial cells due to the nature of their specific bladder disease, autologous cells are not an ideal source clinically, and an alternate cell source must be explored. Adipose derived stem cells (ADSCs) are an attractive cell source for such regenerative medicine applications as they have been extensively studied for their multipotential differentiation, immunosuppressive properties, ease 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 And Synthesis Of Polymer, Carbon And Composite Electrodes For High Energy And High Power Supercapacitors, Margarita Arcila-Velez

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Supercapacitors (SCs) are promising energy storage devices because they deliver energy faster than Li-ion batteries and store larger amounts of charge compared to dielectric capacitors. SCs are classified in electrical double layer capacitors (EDLCs) and pseudocapacitors, based on their charge storage mechanism. EDLCs store charge electrostatically, i.e. by physical charge separation. This mechanism limits the storable amount of energy to the available surface area of the electrode, typically made of carbon materials, but grants good cycling stability of the SC device. Pseudocapacitor electrodes, commonly made of conducting polymers or metal oxides, store charge faradaically, i.e. through redox reactions throughout the …

Characterizing The Effective Bandwidth Of Nonlinear Vibratory Energy Harvesters Possessing Multiple Stable Equilibria, Meghashyam Panyam Mohan Ram

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In the last few years, advances in micro-fabrication technologies have lead to the development of low-power electronic devices spanning critical fields related to sensing, data transmission, and medical implants. Unfortunately, effective utilization of these devices is currently hindered by their reliance on batteries. In many of these applications, batteries may not be a viable choice as they have a fixed storage capacity and need to be constantly replaced or recharged. In light of such challenges, several novel concepts for micro-power generation have been recently introduced to harness, otherwise, wasted ambient energy from the environment and maintain these low-power devices. Vibratory …

Manipulation Of The Electrical Double Layer For Control And Sensing In A Solid State Nanopore, Samuel L. Bearden

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Nanopores have been explored with the goal of achieving non-functionalized, sub-molecular sensors, primarily with the purpose of producing fast, low-cost DNA sequencers. Because of the nanoscale volume within the nanopore structure, it is possible to isolate individual molecular and sub-molecular analytes. Nanopore DNA sequencing has remained elusive due to high noise levels and the challenge of obtaining single-nucleotide resolution. However, the complete electrical double layer within the nanopore is a key feature of fluid-nanopore interaction and has been neglected in previous studies. By exploring interactions with the electrical double layer in various nanopore systems, we characterize the material, electrical, and …

Accuracy, Efficiency, And Parallelism In Network Target Coordination Optimization, Meng Xu

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The optimal design task of complex engineering systems requires knowledge in various domains. It is thus often split into smaller parts and assigned to different design teams with specialized backgrounds. Decomposition based optimization is a multidisciplinary design optimization (MDO) technique that models and improves this process by partitioning the whole design optimization task into many manageable sub-problems. These sub-problems can be treated separately and a coordination strategy is employed to coordinate their couplings and drive their individual solutions to a consistent overall optimum. Many methods have been proposed in the literature, applying mathematical theories in nonlinear programming to decomposition based …

Design Of Cab Suspensions And Semi-Active Seat Damping Control Strategies For Tractor Semi-Trailers, Judhajit Roy

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This thesis uses a high fidelity vertical plane ride model of the tractor semi-trailer to study the effect of different cab design configurations and semi-active seat damper control strategies on the driver’s ride comfort.

The secondary suspensions of a tractor have been an area of particular interest because of the considerable ride comfort improvements they provide. A gap exists in the current engineering domain of an easily configurable high fidelity low computational cost simulation tool to analyze the ride of a tractor semi-trailer. A 15 degree of freedom model of the tractor semi-trailer was used to develop a simulation tool …

Designing A Minimal-Knowledge Controller To Achieve Fast, Stable Growth For Recombinant Escherichia Coli Cultures, Matthew E. Pepper

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The biopharmaceutical industry is constantly developing new recombinant Es-cherichia coli strains to bring new products to market. In early stages of development, small scale bioreactors are used to make the product and explore di˙erent growth pro-tocols. Researchers spend significant time finding a feed rate profile that will give fast growth and low byproduct accumulation. The objective for the controller pre-sented in this work is to achieve fast growth and low acetate accumulation for an E.coli fermentation. The controller does not rely on previous characterization data or models but on fundamental metabolic relationships between oxygen and glucose as dictated by the …

Measurement Of Older And Younger Drivers' Selected Seat Position Within Their Personal Vehicles To Influence Recommended Practices For Meeting Safety Needs Of Drivers, Shayne Kelly Mcconomy

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The objective of this research was to measure and understand the preferred seat position and posture of older drivers and younger drivers within their personal vehicles to influence recommended practices for meeting the safety needs of all drivers.Currently, the United States is experiencing an ageing population, whereby in 2020 nearly 40 million people over the age of 65 will be licensed drivers. In addition, crash reports show that older drivers are over represented in vehicle fatality statistics, once adjusted for vehicle miles traveled. The increased fatality rate of older drivers has been attributed to a combination of increased fragility of …