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ASU Electronic Theses and Dissertations


This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.

In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.

Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.


Subject
Date Range
2011 2019


Demand for green energy alternatives to provide stable and reliable energy solutions has increased over the years which has led to the rapid expansion of global markets in renewable energy sources such as solar photovoltaic (PV) technology. Newest amongst these technologies is the Bifacial PV modules, which harvests incident radiation from both sides of the module. The overall power generation can be significantly increased by using these bifacial modules. The purpose of this research is to investigate and maximize the effect of back reflectors, designed to increase the efficiency of the module by utilizing the intercell light passing through the …

Contributors
MARTIN, PEDRO JESSE, Tamizhmani, Govindasamy, Phelan, Patrick, et al.
Created Date
2019

Lidar has demonstrated its utility in meteorological studies, wind resource assessment, and wind farm control. More recently, lidar has gained widespread attention for autonomous vehicles. The first part of the dissertation begins with an application of a coherent Doppler lidar to wind gust characterization for wind farm control. This application focuses on wind gusts on a scale from 100 m to 1000 m. A detecting and tracking algorithm is proposed to extract gusts from a wind field and track their movement. The algorithm was implemented for a three-hour, two-dimensional wind field retrieved from the measurements of a coherent Doppler lidar. …

Contributors
Zhou, Kai, Calhoun, Ronald, Chen, Kangping, et al.
Created Date
2019

The advancements in additive manufacturing have made it possible to bring life to designs that would otherwise exist only on paper. An excellent example of such designs are the Triply Periodic Minimal Surface (TPMS) structures like Schwarz D, Schwarz P, Gyroid, etc. These structures are self-sustaining, i.e. they require minimal supports or no supports at all when 3D printed. These structures exist in stable form in nature, like butterfly wings are made of Gyroids. Automotive and aerospace industry have a growing demand for strong and light structures, which can be solved using TPMS models. In this research we will try …

Contributors
Raja, Faisal, Phelan, Patrick, Bhate, Dhruv, et al.
Created Date
2019

The construction industry is very mundane and tiring for workers without the assistance of machines. This challenge has changed the trend of construction industry tremendously by motivating the development of robots that can replace human workers. This thesis presents a computed torque controller that is designed to produce movements by a small-scale, 5 degree-of-freedom (DOF) robotic arm that are useful for construction operations, specifically bricklaying. A software framework for the robotic arm with motion and path planning features and different control capabilities has also been developed using the Robot Operating System (ROS). First, a literature review of bricklaying construction activity …

Contributors
Gandhi, Sushrut, Berman, Spring, Marvi, Hamidreza, et al.
Created Date
2019

Hydrogel polymers have been the subject of many studies, due to their fascinating ability to alternate between being hydrophilic and hydrophobic, upon the application of appropriate stimuli. In particular, thermo-responsive hydrogels such as N-Isopropylacrylamide (NIPAM), which possess a unique lower critical solution temperature (LCST) of 32°C, have been leveraged for membrane-based processes such as using NIPAM as a draw agent for forward osmosis (FO) desalination. The low LCST temperature of NIPAM ensures that fresh water can be recovered, at a modest energy cost as compared to other thermally based desalination processes which require water recovery at higher temperatures. This work …

Contributors
Abdullahi, Adnan None, Phelan, Patrick, Wang, Robert, et al.
Created Date
2019

Basilisk lizards are often studied for their unique ability to run across the surface of water. Due to the complicated fluid dynamics of this process, the forces applied on the water’s surface cannot be measured using traditional methods. This thesis presents a novel technique of measuring the forces using a fluid dynamic force platform (FDFP), a light, rigid box immersed in water. This platform, along with a motion capture system, can be used to characterize the kinematics and dynamics of a basilisk lizard running on water. This could ultimately lead to robots that can run on water in a similar …

Contributors
Sweeney, Andrew Joseph, Marvi, Hamidreza, Lentink, David, et al.
Created Date
2019

This thesis presents the design and testing of a soft robotic device for water utility pipeline inspection. The preliminary findings of this new approach to conventional methods of pipe inspection demonstrate that a soft inflatable robot can successfully traverse the interior space of a range of diameter pipes using pneumatic and without the need to adjust rigid, mechanical components. The robot utilizes inflatable soft actuators with an adjustable radius which, when pressurized, can provide a radial force, effectively anchoring the device in place. Additional soft inflatable actuators translate forces along the center axis of the device which creates forward locomotion …

Contributors
Adams, Wade Silas, Aukes, Daniel, Sugar, Thomas, et al.
Created Date
2019

In these times of increasing industrialization, there arises a need for effective and energy efficient heat transfer/heat exchange devices. The focus nowadays is on identifying various methods and techniques which can aid the process of developing energy efficient devices. One of the most common heat transfer devices is a heat exchanger. Heat exchangers are an essential commodity to any industry and their efficiency can play an important role in making industries energy efficient and reduce the energy losses in the devices, in turn decreasing energy inputs to run the industry. One of the ways in which we can improve the …

Contributors
Annam, Roshan Sameer, Phelan, Patrick, Rykaczewski, Konrad, et al.
Created Date
2019

The residential building sector accounts for more than 26% of the global energy consumption and 17% of global CO2 emissions. Due to the low cost of electricity in Kuwait and increase of population, Kuwaiti electricity consumption tripled during the past 30 years and is expected to increase by 20% by 2027. In this dissertation, a framework is developed to assess energy savings techniques to help policy-makers make educated decisions. The Kuwait residential energy outlook is studied by modeling the baseline energy consumption and the diffusion of energy conservation measures (ECMs) to identify the impacts on household energy consumption and CO2 …

Contributors
Alajmi, Turki, Phelan, Patrick E, Kaloush, Kamil, et al.
Created Date
2019

The goal of this paper was to do an analysis of two-dimensional unsplit mass and momentum conserving Finite Volume Methods for Advection for Volume of Fluid Fields with interfaces and validating their rates of convergence. Specifically three unsplit transport methods and one split transport method were amalgamated individually with four Piece-wise Linear Reconstruction Schemes (PLIC) i.e. Unsplit Eulerian Advection (UEA) by Owkes and Desjardins (2014), Unsplit Lagrangian Advection (ULA) by Yang et al. (2010), Split Lagrangian Advection (SLA) by Scardovelli and Zaleski (2003) and Unsplit Averaged Eulerian-Lagrangian Advection (UAELA) with two Finite Difference Methods by Parker and Youngs (1992) and …

Contributors
Ansari, Adil, Herrmann, Marcus, Peet, Yulia, et al.
Created Date
2019

This investigation focuses on the development of uncertainty modeling methods applicable to both the structural and thermal models of heated structures as part of an effort to enable the design under uncertainty of hypersonic vehicles. The maximum entropy-based nonparametric stochastic modeling approach is used within the context of coupled structural-thermal Reduced Order Models (ROMs). Not only does this strategy allow for a computationally efficient generation of samples of the structural and thermal responses but the maximum entropy approach allows to introduce both aleatoric and some epistemic uncertainty into the system. While the nonparametric approach has a long history of applications …

Contributors
Song, Pengchao, Mignolet, Marc P, Smarslok, Benjamin, et al.
Created Date
2019

Rapid expansion of dense beds of fine, spherical particles subjected to rapid depressurization is studied in a vertical shock tube. As the particle bed is unloaded, a high-speed video camera captures the dramatic evolution of the particle bed structure. Pressure transducers are used to measure the dynamic pressure changes during the particle bed expansion process. Image processing, signal processing, and Particle Image Velocimetry techniques, are used to examine the relationships between particle size, initial bed height, bed expansion rate, and gas velocities. The gas-particle interface and the particle bed as a whole expand and evolve in stages. First, the bed …

Contributors
Zunino, Heather, Adrian, Ronald J, Clarke, Amanda, et al.
Created Date
2019

One type of assistive device for the blind has attempted to convert visual information into information that can be perceived through another sense, such as touch or hearing. A vibrotactile haptic display assistive device consists of an array of vibrating elements placed against the skin, allowing the blind individual to receive visual information through touch. However, these approaches have two significant technical challenges: large vibration element size and the number of microcontroller pins required for vibration control, both causing excessively low resolution of the device. Here, I propose and investigate a type of high-resolution vibrotactile haptic display which overcomes these …

Contributors
Wi, Daehan, Sodemann, Angela A, Redkar, Sangram, et al.
Created Date
2019

When air is supplied to a conditioned space, the temperature and humidity of the air often contribute to the comfort and health of the occupants within the space. However, the vapor compression system, which is the standard air conditioning configuration, requires air to reach the dew point for dehumidification to occur, which can decrease system efficiency and longevity in low temperature applications. To improve performance, some systems dehumidify the air before cooling. One common dehumidifier is the desiccant wheel, in which solid desiccant absorbs moisture out of the air while rotating through circular housing. This system improves performance, especially when …

Contributors
Kocher, Jordan, Wang, Robert, Phelan, Patrick, et al.
Created Date
2019

In this research, a new cutting edge wear estimator for micro-endmilling is developed and the reliabillity of the estimator is evaluated. The main concept of this estimator is the minimum chip thickness effect. This estimator predicts the cutting edge radius by detecting the drop in the chip production rate as the cutting edge of a micro- endmill slips over the workpiece when the minimum chip thickness becomes larger than the uncut chip thickness, thus transitioning from the shearing to the ploughing dominant regime. The chip production rate is investigated through simulation and experiment. The simulation and the experiment show that …

Contributors
LEE, JUE-HYUN, Sodemann, Angela A, Shuaib, Abdelrahman, et al.
Created Date
2019

The Basilisk lizard is known for its agile locomotion capabilities on granular and aquatic media making it an impressive model organism for studying multi-terrain locomotion mechanics. The work presented here is aimed at understanding locomotion characteristics of Basilisk lizards through a systematic series of robotic and animal experiments. In this work, a Basilisk lizard inspired legged robot with bipedal and quadrupedal locomotion capabilities is presented. A series of robot experiments are conducted on dry and wet (saturated) granular media to determine the effects of gait parameters and substrate saturation, on robot velocity and energetics. Gait parameters studied here are stride …

Contributors
Jayanetti, Vidu, Marvi, Hamid, Emady, Heather, et al.
Created Date
2019

This dissertation presents the development of structural health monitoring and prognostic health management methodologies for complex structures and systems in the field of mechanical engineering. To overcome various challenges historically associated with complex structures and systems such as complicated sensing mechanisms, noisy information, and large-size datasets, a hybrid monitoring framework comprising of solid mechanics concepts and data mining technologies is developed. In such a framework, the solid mechanics simulations provide additional intuitions to data mining techniques reducing the dependence of accuracy on the training set, while the data mining approaches fuse and interpret information from the targeted system enabling the …

Contributors
Li, Guoyi, Chattopadhyay, Aditi, Mignolet, Marc, et al.
Created Date
2019

Soft polymer composites with improved thermal conductivity are needed for the thermal management of electronics. Interfacial thermal boundary resistance, however, prevents the efficient use of many high thermal conductivity fill materials. Magnetic alignment of ferrous fill material enforces percolation of the high thermal conductivity fill, thereby shifting the governing boundary resistance to the particle- particle interfaces and increasing the directional thermal conductivity of the polymer composite. Magnetic alignment maximizes the thermal conductivity while minimizing composite stiffening at a fill fraction of half the maximum packing factor. The directional thermal conductivity of the composite is improved by more than 2-fold. Particle-particle …

Contributors
Ralphs, Matthew, Rykaczewski, Konrad, Wang, Robert Y, et al.
Created Date
2019

Aging-related damage and failure in structures, such as fatigue cracking, corrosion, and delamination, are critical for structural integrity. Most engineering structures have embedded defects such as voids, cracks, inclusions from manufacturing. The properties and locations of embedded defects are generally unknown and hard to detect in complex engineering structures. Therefore, early detection of damage is beneficial for prognosis and risk management of aging infrastructure system. Non-destructive testing (NDT) and structural health monitoring (SHM) are widely used for this purpose. Different types of NDT techniques have been proposed for the damage detection, such as optical image, ultrasound wave, thermography, eddy current, …

Contributors
Chang, Qinan, Liu, Yongming, Mignolet, Marc, et al.
Created Date
2019

A comprehensive study was performed on non-proprietary ultra-high-performance concrete (UHPC) material and several design methods were suggested based on numerous experimental results. Several sets of compression tests, direct tensile tests, and flexural tests were performed on UHPC to provide a better understanding of the mechanisms involved in the mechanical behavior of the fiber reinforced material. In addition to compressive tests, flexural tests, based on ASTM C1609 and EN 14651, were performed. The effect of the strain rate on the UHPC material was also investigated through the high-speed tensile tests at different strain rates. Alongside the usual measurement tools such as …

Contributors
Kianmofrad, Farrokh, Mobasher, Barzin, Rajan, Subramaniam Dharma, et al.
Created Date
2018

Polymer fibers have broad applications in wearable electronics, bulletproof vests, batteries, fuel cells, filters, electrodes, conductive wires, and biomedical materials. Polymer fibers display light density and flexibility but are mostly weak and compliant. The ceramic, metallic, and carbon nanoparticles have been frequently included in polymers for fabricating continuous, durable, and functional composite fibers. Nanoparticles display large specific areas, low defect density and can transfer their superior properties to polymer matrices. The main focus of this thesis is to design, fabricate and characterize the polymer/nanocarbon composite fibers with unique microstructures and improved mechanical/thermal performance. The dispersions and morphologies of graphene nanoplatelets …

Contributors
Verma, Rahul, Song, Kenan, Jiang, Hanqing, et al.
Created Date
2018

Toward the ambitious long-term goal of developing a robotic circus, this thesis addresses key steps toward the development of a ground robot that can catch a ball. Toward this end, we examine nonlinear quadratic drag trajectories for a tossed ball. Relevant least square error fits are provided. It is also shown how a Kalman filter and Extended Kalman filter can be used to generate estimates for the ball trajectory. Several simple ball intercept policies are examined. This includes open loop and closed loop policies. It is also shown how a low-cost differential-drive research grade robot can be built, modeled and …

Contributors
DAS, NIRANGKUSH, RODRIGUEZ, ARMANDO A, BERMAN, SPRING M, et al.
Created Date
2018

Advanced material systems refer to materials that are comprised of multiple traditional constituents but complex microstructure morphologies, which lead to their superior properties over conventional materials. This dissertation is motivated by the grand challenge in accelerating the design of advanced material systems through systematic optimization with respect to material microstructures or processing settings. While optimization techniques have mature applications to a large range of engineering systems, their application to material design meets unique challenges due to the high dimensionality of microstructures and the high costs in computing process-structure-property (PSP) mappings. The key to addressing these challenges is the learning of …

Contributors
Cang, Ruijin, Ren, Yi, Liu, Yongming, et al.
Created Date
2018

Wearable robotics has gained huge popularity in recent years due to its wide applications in rehabilitation, military, and industrial fields. The weakness of the skeletal muscles in the aging population and neurological injuries such as stroke and spinal cord injuries seriously limit the abilities of these individuals to perform daily activities. Therefore, there is an increasing attention in the development of wearable robots to assist the elderly and patients with disabilities for motion assistance and rehabilitation. In military and industrial sectors, wearable robots can increase the productivity of workers and soldiers. It is important for the wearable robots to maintain …

Contributors
Chinimilli, Prudhvi Tej, Redkar, Sangram, Zhang, Wenlong, et al.
Created Date
2018

This paper describes an effort to bring wing structural stiffness and aeroelastic considerations early in the conceptual design process with an automated tool. Stiffness and aeroelasticity can be well represented with a stochastic model during conceptual design because of the high level of uncertainty and variability in wing non-structural mass such as fuel loading and control surfaces. To accomplish this, an improvement is made to existing design tools utilizing rule based automated design to generate wing torque box geometry from a specific wing outer mold-line. Simple analysis on deflection and inferred stiffness shows how early conceptual design choices can strongly …

Contributors
Miskin, Daniel L, Takahashi, Timothy T, Mignolet, Marc, et al.
Created Date
2018

Owing to the surge in development of endovascular devices such as coils and flow diverter stents, doctors are inclined to approach surgical cases non-invasively more often than before. Treating brain aneurysms as a bulging of a weakened area of a blood vessel is no exception. Therefore, promoting techniques that can help surgeons have a better idea of treatment outcomes are of invaluable importance. In order to investigate the effects of these devices on intra-aneurysmal hemodynamics, the conventional computational fluid dynamics (CFD) approach uses the explicit geometry of the device within an aneurysm and discretizes the fluid domain to solve the …

Contributors
Yadollahi Farsani, Hooman, Herrmann, Marcus, Frakes, David, et al.
Created Date
2018

Multiaxial mechanical fatigue of heterogeneous materials has been a significant cause of concern in the aerospace, civil and automobile industries for decades, limiting the service life of structural components while increasing time and costs associated with inspection and maintenance. Fiber reinforced composites and light-weight aluminum alloys are widely used in aerospace structures that require high specific strength and fatigue resistance. However, studying the fundamental crack growth behavior at the micro- and macroscale as a function of loading history is essential to accurately predict the residual fatigue life of components and achieve damage tolerant designs. The issue of mechanical fatigue can …

Contributors
Datta, Siddhant, Chattopadhyay, Aditi, Liu, Yongming, et al.
Created Date
2018

Geometrical tolerances define allowable manufacturing variations in the features of mechanical parts. For a given feature (planar face, cylindrical hole) the variations may be modeled with a T-Map, a hyper solid in 6D small displacement coordinate space. A general method for constructing T-Maps is to decompose a feature into points, identify the variational limits to these points allowed by the feature tolerance zone, represent these limits using linear halfspaces, transform these to the central local reference frame and intersect these to form the T-Map for the entire feature. The method is explained and validated for existing T-Map models. The method …

Contributors
Chitale, Aniket, Davidson, Joseph, Sugar, Thomas, et al.
Created Date
2018

The world population is aging. Age-related disorders such as stroke and spinal cord injury are increasing rapidly, and such patients often suffer from mobility impairment. Wearable robotic exoskeletons are developed that serve as rehabilitation devices for these patients. In this thesis, a knee exoskeleton design with higher torque output compared to the first version, is designed and fabricated. A series elastic actuator is one of the many actuation mechanisms employed in exoskeletons. In this mechanism a torsion spring is used between the actuator and human joint. It serves as torque sensor and energy buffer, making it compact and safe. A …

Contributors
Jhawar, Vaibhav, Zhang, Wenlong, Sugar, Thomas G, et al.
Created Date
2018

Lower-limb wearable assistive robots could alter the users gait kinematics by inputting external power, which can be interpreted as mechanical perturbation to subject normal gait. The change in kinematics may affect the dynamic stability. This work attempts to understand the effects of different physical assistance from these robots on the gait dynamic stability. A knee exoskeleton and ankle assistive device (Robotic Shoe) are developed and used to provide walking assistance. The knee exoskeleton provides personalized knee joint assistive torque during the stance phase. The robotic shoe is a light-weighted mechanism that can store the potential energy at heel strike and …

Contributors
Rezayat Sorkhabadi, Seyed Mostafa, Zhang, Wenlong, Lee, Hyunglae, et al.
Created Date
2018

Additive manufacturing (AM) describes an array of methods used to create a 3D object layer by layer. The increasing popularity of AM in the past decade has been due to its demonstrated potential to increase design flexibility, produce rapid prototypes, and decrease material waste. Temporary supports are an inconvenient necessity in many metal AM parts. These sacrificial structures are used to fabricate large overhangs, anchor the part to the build substrate, and provide a heat pathway to avoid warping. Polymers AM has addressed this issue by using support material that is soluble in an electrolyte that the base material is …

Contributors
Lefky, Christopher, Hildreth, Owen, Chawla, Nikhilesh, et al.
Created Date
2018

The objective of this dissertation is to study the use of metamaterials as narrow-band and broadband selective absorbers for opto-thermal and solar thermal energy conversion. Narrow-band selective absorbers have applications such as plasmonic sensing and cancer treatment, while one of the main applications of selective metamaterials with broadband absorption is efficiently converting solar energy into heat as solar absorbers. This dissertation first discusses the use of gold nanowires as narrow-band selective metamaterial absorbers. An investigation into plasmonic localized heating indicated that film-coupled gold nanoparticles exhibit tunable selective absorption based on the size of the nanoparticles. By using anodized aluminum oxide …

Contributors
Alshehri, Hassan, Wang, Liping, Phelan, Patrick, et al.
Created Date
2018

In this thesis, different H∞ observers for time-delay systems are implemented and their performances are compared. Equations that can be used to calculate observer gains are mentioned. Different methods that can be used to implement observers for time-delay systems are illustrated. Various stable and unstable systems are used and H∞ bounds are calculated using these observer designing methods. Delays are assumed to be known constants for all systems. H∞ gains are calculated numerically using disturbance signals and performances of observers are compared. The primary goal of this thesis is to implement the observer for Time Delay Systems designed using SOS …

Contributors
Talati, Rushabh Vikram, Peet, Matthew, Berman, Spring, et al.
Created Date
2018

Thermodynamic development and balance of plant study is completed for a 30 MW solar thermochemical water splitting process that generates hydrogen gas and electric power. The generalized thermodynamic model includes 23 components and 45 states. Quasi-steady state simulations are completed for design point system sizing, annual performance analysis and sensitivity analysis. Detailed consideration is given to water splitting reaction kinetics with governing equations generalized for use with any redox-active metal oxide material. Specific results for Ceria illustrate particle reduction in two solar receivers for target oxygen partial pressure of 10 Pa and particle temperature of 1773 K at a design …

Contributors
Budama, Vishnu Kumar, Johnson, Nathan, Stechel, Ellen, et al.
Created Date
2018

Soft Poly-Limb (SPL) is a pneumatically driven, wearable, soft continuum robotic arm designed to aid humans with medical conditions, such as cerebral palsy, paraplegia, cervical spondylotic myelopathy, perform activities of daily living. To support user's tasks, the SPL acts as an additional limb extending from the human body which can be controlled to perform safe and compliant mobile manipulation in three-dimensional space. The SPL is inspired by invertebrate limbs, such as the elephant trunk and the arms of the octopus. In this work, various geometrical and physical parameters of the SPL are identified, and behavior of the actuators that comprise …

Contributors
Nuthi, Sai Gautham, Polygerinos, Panagiotis, Lee, Hyunglae, et al.
Created Date
2018

The concept of this thesis came up as a part of the efforts being devoted around the world to reduce energy consumption, CO2 emissions, global warming and ozone layer depletion. In the United States, HVAC units in residential buildings consumed about 350 billion kWh in 2017 [1],[2]. Although HVAC manufacturers are investing in new technologies and more efficient products to reduce energy consumption, there is still room for further improvement. One way of reducing cooling and heating energy in residential buildings is by allowing the centralized HVAC unit to supply conditioned air to only occupied portions of the house by …

Contributors
Fairag, Amr, Phelan, Patrick, Bocanegra, Luis, et al.
Created Date
2018

As additive manufacturing grows as a cost-effective method of manufacturing, lighter, stronger and more efficient designs emerge. Heat exchangers are one of the most critical thermal devices in the thermal industry. Additive manufacturing brings us a design freedom no other manufacturing technology offers. Advancements in 3D printing lets us reimagine and optimize the performance of the heat exchangers with an incredible design flexibility previously unexplored due to manufacturing constraints. In this research, the additive manufacturing technology and the heat exchanger design are explored to find a unique solution to improve the efficiency of heat exchangers. This includes creating a Triply …

Contributors
Chandrasekaran, Gokul, Phelan, Patrick E, Rykaczewski, Konrad, et al.
Created Date
2018

In this work, different methods for fabrication of flexible sensors and sensor characterization are studied. Using materials and equipment that is unconventional, it is shown that different processes can be used to create sensors that behave like commercially available sensors. The reason unconventional methods are used is to cut down on cost to produce the sensors as well as enabling the manufacture of custom sensors in different sizes and different configurations. Currently commercially available sensors are expensive and are usually designed for very specific applications. By creating these same types of sensors using new methods and materials, these new sensors …

Contributors
Casanova, Lucas Montgomery, Redkar, Sangram, Rogers, Bradley, et al.
Created Date
2018
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This thesis focuses on an improved understanding of the dynamics at different length scales of wind farms in an atmospheric boundary layer (ABL) using a series of visualization studies and Fourier, wavelet based spectral analysis using high fidelity large eddy simulation (LES). For this purpose, a robust LES based neutral ABL model at very high Reynolds number has been developed using a high order spectral element method which has been validated against the previous literature. This ABL methodology has been used as a building block to drive large wind turbine arrays or wind farms residing inside the boundary layer as …

Contributors
Chatterjee, Tanmoy, Peet, Yulia T., Adrian, Ronald J., et al.
Created Date
2018

Liquid injection in cross flows has applications in gas-turbine engines, afterburners and some rocket combustion chambers. Integral form of the conservation equations has been used to find a cubic formula for the drop size in liquid sprays in cross flows. Similar to the work on axial liquid sprays, the energy balance dictates that the initial kinetic energy of the gas and injected liquid be distributed into the final surface tension energy, kinetic energy of the gas and droplets, and viscous dissipation incurred. Kinetic energy of the cross flow is added to the energy balance. Then, only the viscous dissipation term …

Contributors
Park, Jung Eun, Lee, Taewoo, Huang, Huei-ping, et al.
Created Date
2018

In this study, two novel sorbents (zeolite 4A and sodium polyacrylate) are tested to investigate if utilizing ultrasonic acoustic energy could decrease the amount of time and overall energy required to regenerate these materials for use in cooling applications. To do this, an experiment was designed employing a cartridge heater and a piezoelectric element to be simultaneously providing heat and acoustic power to a custom designed desorption bed while measuring the bed mass and sorbent temperature at various locations. The results prove to be promising showing that early in the desorption process ultrasound may expedite the desorption process in zeolite …

Contributors
Bertrand, Weston Kyle, Phelan, Patrick, Bocanegra, Luis, et al.
Created Date
2018

Membrane filtration is an important technology in industry. In the past few decades, equations have been developed from experimental results to predict cake formation and permeate flux decline in the membrane filtration process. In the current work, the block of particles on membrane surface is achieved by setting surface flux on membrane surface zero. This approach is implemented for both microfiltration and nanofiltration using OpenFOAM. Moreover, a new method to deal with cake resistance for nanofiltration is introduced. Cake resistance is applied to both cake and membrane. To validate the new techniques, results of crossflow microfiltration are compared to theoretical …

Contributors
Hu, Jueming, Herrmann, Marcus, Huang, Huei-Ping, et al.
Created Date
2018

Energy harvesting from ambient is important to configuring Wireless Sensor Networks (WSN) for environmental data collecting. In this work, highly flexible thermoelectric generators (TEGs) have been studied and fabricated to supply power to the wireless sensor notes used for data collecting in hot spring environment. The fabricated flexible TEGs can be easily deployed on the uneven surface of heated rocks at the rim of hot springs. By employing the temperature gradient between the hot rock surface and the air, these TEGs can generate power to extend the battery lifetime of the sensor notes and therefore reduce multiple batteries changes where …

Contributors
Han, Ruirui, Yu, Hongyu, Jiang, Hanqing, et al.
Created Date
2018

This dissertation will investigate two of the most promising high-capacity anode materials for lithium-based batteries: silicon (Si) and metal lithium (Li). It will focus on studying the mechanical behaviors of the two materials during charge and discharge and understanding how these mechanical behaviors may affect their electrochemical performance. In the first part, amorphous Si anode will be studied. Despite many existing studies on silicon (Si) anodes for lithium ion batteries (LIBs), many essential questions still exist on compound formation, composition, and properties. Here it is shown that some previously accepted findings do not truthfully reflect the actual lithiation mechanisms in …

Contributors
Wang, Xu, Jiang, Hanqing, Yu, Hongbin, et al.
Created Date
2018

Interstitial impurity atoms can significantly alter the chemical and physical properties of the host material. Oxygen impurity in HCP titanium is known to have a considerable strengthening effect mainly through interactions with dislocations. To better understand such an effect, first the role of oxygen on various slip planes in titanium is examined using generalized stacking fault energies (GSFE) computed by the first principles calculations. It is shown that oxygen can significantly increase the energy barrier to dislocation motion on most of the studied slip planes. Then the Peierls-Nabbaro model is utilized in conjunction with the GSFE to estimate the Peierls …

Contributors
Gholami Bazehhour, Benyamin, Solanki, Kiran N, Liu, Yongming, et al.
Created Date
2018

The stability of nanocrystalline microstructural features allows structural materials to be synthesized and tested in ways that have heretofore been pursued only on a limited basis, especially under dynamic loading combined with temperature effects. Thus, a recently developed, stable nanocrystalline alloy is analyzed here for quasi-static (<100 s-1) and dynamic loading (103 to 104 s-1) under uniaxial compression and tension at multiple temperatures ranging from 298-1073 K. After mechanical tests, microstructures are analyzed and possible deformation mechanisms are proposed. Following this, strain and strain rate history effects on mechanical behavior are analyzed using a combination of quasi-static and dynamic strain …

Contributors
Turnage, Scott Andrew, Solanki, Kiran N, Rajagopalan, Jagannathan, et al.
Created Date
2017

7XXX Aluminum alloys have high strength to weight ratio and low cost. They are used in many critical structural applications including automotive and aerospace components. These applications frequently subject the alloys to static and cyclic loading in service. Additionally, the alloys are often subjected to aggressive corrosive environments such as saltwater spray. These chemical and mechanical exposures have been known to cause premature failure in critical applications. Hence, the microstructural behavior of the alloys under combined chemical attack and mechanical loading must be characterized further. Most studies to date have analyzed the microstructure of the 7XXX alloys using two dimensional …

Contributors
Stannard, Tyler, Chawla, Nikhilesh, Solanki, Kiran N, et al.
Created Date
2017

The exceptional mechanical properties of polymers with heterogeneous structure, such as the high toughness of polyethylene and the excellent blast-protection capability of polyurea, are strongly related to their morphology and nanoscale structure. Different polymer microstructures, such as semicrystalline morphology and segregated nanophases, lead to coordinated molecular motions during deformation in order to preserve compatibility between the different material phases. To study molecular relaxation in polyethylene, a coarse-grained model of polyethylene was calibrated to match the local structural variable distributions sampled from supercooled atomistic melts. The coarse-grained model accurately reproduces structural properties, e.g., the local structure of both the amorphous and …

Contributors
Li, Yiyang, Oswald, Jay, Rajan, Subramaniam, et al.
Created Date
2017

In this work, different passive prosthetic ankles are studied. It is observed that complicated designs increase the cost of production, but simple designs have limited functionality. A new design for a passive prosthetic ankle is presented that is simple to manufacture while having superior functionality. This prosthetic ankle design has two springs: one mimicking Achilles tendon and the other mimicking Anterior-Tibialis tendon. The dynamics of the prosthetic ankle is discussed and simulated using Working model 2D. The simulation results are used to optimize the springs stiffness. Two experiments are conducted using the developed ankle to verify the simulation It is …

Contributors
Bhat, Sandesh Ganapati, Redkar, Sangram, Sugar, Thomas, et al.
Created Date
2017

Aluminum alloys are ubiquitously used in almost all structural applications due to their high strength-to-weight ratio. Their superior mechanical performance can be attributed to complex dispersions of nanoscale intermetallic particles that precipitate out from the alloy’s solid solution and offer resistance to deformation. Although they have been extensively investigated in the last century, the traditional approaches employed in the past haven’t rendered an authoritative microstructural understanding in such materials. The effect of the precipitates’ inherent complex morphology and their three-dimensional (3D) spatial distribution on evolution and deformation behavior have often been precluded. In this study, for the first time, synchrotron-based …

Contributors
Kaira, Chandrashekara Shashank, Chawla, Nikhilesh, Solanki, Kiran, et al.
Created Date
2017