Matching Items (306)
Description
The overall goal of this project is to use metallic nanoparticles to develop a thin, ductile amorphous film at room temperature. Currently bulk metallic glasses are mainly formed via quenching, which requires very high cooling rates to achieve an amorphous molecular structure. These formations often fail in a brittle manner. The advantages of using a bottom-up approach with amorphous nanoparticles at ambient conditions is that the ductility of the metal can be improved, and the process will be less energy intensive. The nanoparticles used are iron precursors with ATMP and DTPMP ligand stabilizers and dispersed in methanol. Three forms of experimentation were applied over the course of this project. The first was a simple, preliminary data collection approach where the particles were dispersed onto a glass slide and left to dry under various conditions. The second method was hypersonic particle deposition, which accelerated the particles to high speeds and bombarded onto a glass or silicon substrate. The third method used Langmuir-Blodgett concepts and equipment to make a film. Qualitative analyses were used to determine the efficacy of each approach, including SEM imaging. In the end, none of the approaches proved successful. The first approach showed inconsistencies in the film formation and aggregation of the particles. The results from the hypersonic particle deposition technique showed that not enough particles were deposited to make a consistent film, and many of the particles that were able to be deposited were aggregated. The Langmuir-Blodgett method showed potential, but aggregation of the particles and uneven film formation were challenges here as well. Although there are ways the three discussed experimental approaches could be optimized, the next best step is to try completely new approaches, such as convective assembly and 3D printing to form the ideal nanoparticle film.
ContributorsKline, Katelyn Ann (Author) / Lind, Mary Laura (Thesis director) / Cay, Pinar (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Zeolite thin films and membranes are currently a promising technology for pervaporation, gas separation and water purification. The main drawback with these technologies is that the synthesis is not consistent leading to varied and unreproducible results. The Langmuir-Blodgett technique is a robust method for transferring monolayers of molecules or crystals to a solid substrate. By measuring the surface pressure and controlling the area, reliable results can be achieved by transferring monolayers to different solid substrates. It has been shown previously that various types of zeolites can be functionalized and dispersed on the top of water. This is done by using an alcohol to form a hydrophobic coating on the surface of zeolite. The Langmuir-Blodgett can be used to create thin, compact films of zeolites for synthesizing and growing zeolite films. For the first reported time, cubic LTA Zeolites monolayers have been assembled with the Langmuir-Blodgett technique with multiple solvents and different sizes of zeolites. These films were characterized with Scanning Electron Microscopy and Pressure-Area Isotherms generated from the Langmuir-Blodgett. It was found that linoleic acid is a required addition to the zeolite dispersions to protect the mechanical stability during agitation. Without this addition, the LTA zeolites are broken apart and lose their characteristic cubic structure. This effect is discussed and a theory is presented that the interparticle interactions of the long alkane chain of the linoleic acid help reduce the shear stress on the individual zeolite particles, thus preventing them from being broken. The effect of size of the zeolites on the monolayer formation was also discussed. There seemed to be little correlation between the monolayer quality and formation as size was changed. However, to optimize the process, different concentrations and target pressures are needed. Lastly, the effect of the solvent was explored and it was found that there is a different between monolayer formations for different solvents likely due to differing interparticle interactions. Overall, LTA zeolites were successfully fabricated and the important factors to consider are the zeolite size, the solvent, and the amount of surfactant stabilizer added.
ContributorsDopilka, Andrew Michael (Author) / Lind, Mary Laura (Thesis director) / Cay, Pinar (Committee member) / Materials Science and Engineering Program (Contributor) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
The Tempe Streetcar is a local trolley system that currently provides free transportation for passengers traveling around Arizona State University (ASU) and downtown Tempe. While the system is a valuable resource for students and commuters, there tends to be a discrepancy between the scheduled arrival times and the actual arrival times of the streetcar especially during high-traffic times of the day. This inconsistency poses challenges for ASU students who rely on timely transportation for classes, exams, work, and other commitments. To address this issue, this thesis presents a solution by developing a solar-powered, auditory, and visual notification system for Tempe Streetcar stops. The system displays real-time arrival updates and provides audible alerts when the streetcar is approaching. This system makes it accessible for both hearing and vision impaired users and those without mobile devices. It leverages a GPS tracker that monitors the streetcar’s location and transmits the data to a cloud database. Each stop’s local microcontroller independently retrieves this data to trigger the notification system's outputs. This solution and thesis project is an extension of an electrical engineering capstone project. The capstone project includes the development of the GPS tracker, corresponding website, and mobile application to help users track the streetcar's location in real time. A QR code placed at each stop links to the live tracking website which improves access for first-time riders or those without the mobile app. The entire system is powered sustainably through solar energy and takes advantage of the stationary nature of streetcar stops. Through this notification system, this thesis hopes to provide passengers with precise arrival times and enhance the reliability of the Tempe Streetcar ensuring that users can plan their travel with greater confidence and encourage future use of the streetcar.
ContributorsDuran, Abraham (Author) / Patel, Veraj (Co-author) / Lewis, John (Thesis director) / Ranjram, Mike (Committee member) / Barrett, The Honors College (Contributor) / Electrical Engineering Program (Contributor)
Created2025-05
Description
Microbial dysbiosis is a condition where one’s gut bacteria colonies and species are imbalanced due to infection, antibiotics, and diet. Dysbiosis can lead to chronic illnesses like inflammatory bowel disease where current clinical treatments, such as probiotics and fecal matter transplant, have limitations from precisely delivering the right bacteria species in the right location in the gastrointestinal tract. With recent developments of magnetically actuated endoscopy bots which are precisely controlled and less invasive, magnetically-controlled robotic solutions can be applied to solving microbial dysbiosis. Two GI bot designs were developed, an accordion and concertina design, which differ in geometry. These designs involved a soft Ecoflex body, four ring magnets that are made of NdFeB and Ecoflex (in a 4:1 weight ratio) and magnetically actuated in the same direction, and a 3D-printed plastic capsule. The design rationale involved introducing the GI bot to external magnetic fields to deliver a payload, i.e. bacteria, for an application in solving microbial dysbiosis.
First, the design was optimized. Tensile and compression testing were used to determine an optimal Ecoflex coating combination with Ecoflex 00-10 making the first layer and Ecoflex 00-50 making the second layer. Afterward, two main functions were tested for in the robot: (1) precise magnetic control of the robot’s movement and direction and (2) magnetic control of the GI bot’s compression to trigger a payload release. Orientation control of the GI bot was demonstrated with a robot arm introducing a magnetic field of 4.08 mT. The test demonstrated proper control of the robot for five degrees of freedom. Lastly, delivery capabilities for the designs were established under a 173 mT external magnetic field with the accordion and concertina having dyed water (payload) release efficiencies of 35.33% and 40.16% respectively. From these results, a GI bot in the gut is achievable, and the accordion or concertina models provide a basis for further exploring and optimizing the safety and efficiency of this clinical robotic and magnetic solution. Moreover, the results showcase that magnetic actuation can be used for both orientation and delivery control as they are decoupled based on the external magnetic field strength.
ContributorsNguyen, Sophie (Author) / Marvi, Hamidreza (Thesis director) / Ceylan, Hakan (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / Chemical Engineering Program (Contributor)
Created2023-12
Description
As high-power equipment becomes more compact, there is an increasing need for effective insulating materials to ensure reliability. High-voltage systems often face issues with uneven electric fields, especially at ”triple points” where metal, dielectric, and gas meet, leading to material degradation and failure risks. Additionally, advanced semiconductor technology introduces higher voltage demands, which challenge dielectric integrity in power electronics, causing frequent partial discharges (PD) and surface flashovers. Square wave voltages, in particular, produce higher magnitude PD events that accelerate insulation aging more than sinusoidal voltages.This Ph.D. project investigates ways to mitigate these electric stresses in high-voltage insulation. First, nonlinear field grading (NLRFG) materials are studied for their ability to reduce electric field stress in equipment like cable joints, and results are modeled in finite element analysis (FEA). Next, capacitive field grading composites (FCFGCs) are tested for PD reduction in motor windings under rapid power electronic pulses. Finally, the effectiveness of NLRFG and FCFGC in mitigating stress on direct bonded copper (DBC) substrates is evaluated, alongside the impact of electret films on reducing PD in liquid metal polymer composites (LMPCs).
ContributorsFaruqe, Omar (Author) / Park, Chanyeop (Thesis advisor) / Bailey, Christopher (Committee member) / Ranjram, Mike (Committee member) / Mantooth, Alan (Committee member) / Arizona State University (Publisher)
Created2025
Description
Shear-thinning hydrogels can be combined with other components to enable multi-functionality, including short fibers or particles [1]. For the inclusion of fibers, electrospinning has gained momentum as a simple technique to create tissue engineered scaffolds that mimic the fibrous nature of the extracellular matrix [2]. Combining electrospun fibers with a shear-thinning hydrogel has the potential to provide cells with essential physical cues while retaining injectability [3]. Cells do not adhere well to hyaluronic acid alone, thus, peptides or fibers can be incorporated into the hydrogel mixture to improve cell adherence and facilitate better cell-material interactions [1,4]. In the future, hydrogel composite systems including fibers and/or peptides can be manufactured using shear-thinning hydrogels as an ideal multi-functional, injectable hydrogel for tissue repair applications. To establish the effect of these components on composite injectability, injection force experiments were conducted to quantify break and glide force. There was no statistically significant difference in break force of Ad-MeHA + CD-HA guest-host hydrogels of 5 wt%, 6 wt%, 6 wt% with peptides, and 7 wt% HA. A significant difference (p < 0.001) in glide force of Ad-MeHA + CD-HA guest-host hydrogels between 5wt% and 7wt% was observed. There was no statistically significant difference in break force or glide force of Ad-MeHA + CD-HA 7 wt% guest-host hydrogels of 0, 0.5, or 1 wt% fibers (40 µm, 15% SPIONs).
ContributorsKhandelwal, Juhi (Author) / Holloway, Julianne (Thesis director) / Stabenfeldt, Sarah (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2025-05
Description
The gold standard of treatment for large bone defects remains autograft bone, which suffers from limited availability and donor-site morbidity. As an alternative, bone tissue engineering seeks to use a combination of cells, biomolecules, and biomaterials to regenerate functional bone tissue. Hydroxyapatite is a key component of bone tissue and is particularly important for its function. Here, we developed an approach to mineralize electrospun fibers to mimic native bone mineralization and serve as a scaffold for bone repair. Two types of electrospun fiber systems were investigated: polycaprolactone (PCL) and norbornene-functionalized cellulose acetate (nor-CA). PCL fiber surfaces were activated with sodium hydroxide and calcium phosphate. Next, the fibrous scaffolds were incubated in simulated body fluid (SBF) for seven days. Three types of SBF were chosen for incubation: conventional (C-SBF), revised (R-SBF), and 4x revised (4x R-SBF). Mineralization was assessed using energy-dispersive X-ray spectroscopy, Alizarin Red S staining, and scanning electron microscopy. Calcium phosphate and sodium chloride-based mineralization were observed for all SBF formulations for PCL. 4x R-SBF resulted in a calcium-to-phosphorus molar ratio most like native hydroxyapatite. R-SBF also had a calcium-to-phosphorus ratio similar to that of hydroxyapatite. R-SBF and 4x R-SBF resulted in lower values of sodium deposition on PCL when compared to C-SBF and had distinct regions of calcium-phosphate and sodium-chloride mineralization. Nor-CA was synthesized using a Boc2O esterification reaction between 5-norbornene-2-carboxylic acid and cellulose acetate, and analysis revealed the norbornene functionalization to be 60.02%. A fluorescent dye, 7-mercapto-4-methylcoumarin, was also successfully bound to the surface of nor-CA fibers using a UV-mediated thiol-ene reaction. The selectivity of the reaction between samples exposed to UV and kept in the dark requires improvement in future work.
ContributorsKupfer, Joshua (Author) / Holloway, Julianne (Thesis director) / Schwarz, Grace (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2025-05
Description
The large-scale integration of distributed energy resources (DERs) into the electric grid comes with unforeseen challenges for the utilities. Voltage rise due to the high penetration of DERs is an important problem to be solved to increase renewable energy generation in modern grids. Utilizing grid-connected power converters for improving the distribution grid power quality, reliability, and resilience is becoming increasingly popular with the widespread adoption of DERs. This report proposes two distribution grid voltage regulation schemes using DERs to regulate the grid voltage effectively. A distributed voltage control scheme using only local measurements, similar to volt-VAr control, is suggested to overcome some drawbacks related to voltage-reactive power control. An active distribution grid control is proposed to regulate the node voltage for all the nodes in the feeder effectively, with an emphasis on minimizing the total reactive power. These controls are tested on a large, 8000+ node distribution feeder with peak instantaneous penetration of over 230% from DERs. The controls are implemented in a real-time power hardware testbed to validate the implementation and the performance.
In addition to DER inverters, the penetration levels of several other multi-kW scale, grid-edge devices controlled by power electronic converters have also been rapidly increasing. These include on-board electric vehicle chargers, residential energy storage, and high-power computers used for data mining with power levels of 2 kW or above. They all need to meet stringent requirements on harmonic and high-frequency distortion limits, high efficiency, and high power factor with a front-end power factor correction circuit (PFC). Power density is also a very important metric, especially for electric vehicle chargers. This work proposes and experimentally validates a new circuit topology based on an active clamped SEPIC converter for the isolated, power-factor correction circuits well-suited for the above applications.
The increasing integration of Inverter-Based Resources (IBRs) within transmission grids introduces novel challenges related to stability, reliability, and control, which stem from their distinct dynamics, rapid-response characteristics, and limited short-circuit current capability. While traditional simulation tools are proficient, they encounter challenges in accurately depicting the real-time interactions and behaviors of IBRs under various operating conditions. This thesis briefly explores the necessity of digital twins for analyzing IBR-dominant transmission grids, emphasizing their significance in stability analysis. It also proposes a co-simulation framework based on HELICS to develop a digital twin by incorporating multi-domain simulation tools such as ePHASORSIM and PSCAD, facilitating a comprehensive real-time simulation for large-scale IBR-dominant power systems.
ContributorsSondharangalla, Madhura B (Author) / Ayyanar, Raja (Thesis advisor) / Vittal, Vijay (Committee member) / Ranjram, Mike (Committee member) / Srinivasan, Devarajan (Committee member) / Arizona State University (Publisher)
Created2025
Description
The process of wet granulation is a widely used process in which fine particles are agglomerated into a larger particle using a liquid binder. Understanding this process can help to standardize powder properties and improve transport efficiency. The practice of granulation is really influenced by various particle properties, powder properties, and specifications of equipment design. Determining how to predict the formation and breakage of granules in a consistent and predictable manner are important for its industrial applications and future research studies.
This study first looked at how penetration time of a drop into a powder bed depends on the impact velocity of the drop for several different viscosity liquid binders. A high-speed camera captured the impact time at several different height values of single-drop granulation. For lower viscosity liquids, penetration time decreases with increasing impact velocity. However, the trend reverses when using very high viscosity liquid binders. Another aim of this study was to look at granule breakage as a function of rotational speed in a granulator with several liquid binders with varying properties. 20 single-drop granules were made separately and placed in a high-shear granulator, where after 1 minute of mixing the final breakage fraction was recorded. Breakage rate generally increases with higher rotational speeds, however several factors such as viscosity, surface tension, and granule saturation also affect this breakage.
ContributorsMomeyer, Jason (Author) / Emady, Heather (Thesis director) / Kumar, Diana (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2025-05
Description
In this work, a series of polydimethylsiloxane (PDMS) composite membranes were fabricated by using vinyl-terminated PDMS with polyhydomethylsiloxane (PHMS) as a cross-linker, with a hydrophobic DeltaMem PERVAPTM 4155-80 support layer, through drawdown casting with a doctor blade. The original goal of the work was to control cross-link density of the membranes by varying the ratio of cross-linker to PDMS, and examining the effect of cross-link density on performance of the membranes under pervaporation. The goal of the work shifted to optimizing the fabrication procedure to produce usable membranes after initial attempts at fabrication were unsuccessful. It was found that viscosity of the polymer solution, heating time, degassing time, and the application of the support layer played key roles in determining the success of the membrane fabrication. No usable membranes were fabricated and pervaporation data was not collected, but many insights were gained into the process of membrane fabrication and the different methods that can be used to fabricate PDMS membranes. This work demonstrated the need for further study into alternative methods for membrane fabrication, and key avenues to explore to optimize the process.
ContributorsAskew, Bryce (Author) / Green, Matthew (Thesis director) / Telenar, Taysha (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2025-05