SHAREOK Repository
Not a member yet
49261 research outputs found
Sort by
Finite element modeling of residual mechanical hearing function after cochlear implant surgery
Get PDFCochlear implant (CI) surgery is one of the most utilized treatments for severe
hearing loss. Though CI surgery is proven to improve patients’ quality of life,
results are variable as damage to very delicate inner ear tissues can be difficult
to avoid. However, even the effects of optimal scala tympani insertions on the
mechanics of hearing are not yet fully understood. This project presents two
finite element models of the inner ear to study the interrelationship between the
mechanical function of the cochlea and the insertion of a cochlear implant electrode,
one derived from the chinchilla inner ear and one derived from the rhesus monkey
inner ear. These subjects were chosen due to their wide usage in inner ear research
as designs of the typical device tend to progress from chinchilla animal studies,
to rhesus animal studies, and finally to human trials. Both FE models include a
three-chambered cochlea and full vestibular system, rarely seen in prior studies.
The procedure used to create these models is low-cost, rapid, and reproducible,
and results in a highly detailed model using μMRI imaging as the data source.
In the chinchilla model’s unimplanted state, data indicative of the tuning effect
of the cochlea closely matched results obtained in In Vivo studies. In its implanted
state, the chinchilla model found minimal loss of residual hearing or alteration of
the cochlea’s tuning effect regardless of CI insertion angle. Its results suggest
that an emphasis should be put on developing CI’s with maximal insertion angles
and minimal trauma during insertion. The more detailed rhesus model is presented
with its preliminary results and plans for its continued development. In the future,
both models can be reused with minimal alteration to study a broad range of
phenomena such as vestibulo-cochlear interaction, the results of vestibular implant
surgery, and the effects of various pathologies on hearing function
Design strategies to minimize waste
Get PDFThis research study is focused on obtaining waste minimization strategies that designers can apply to their projects. With a rapid increase in construction recently, the high production of waste produced is dumped in landfills after being used without segregating them with hazardous material or considering if the material can be re-used.
This paper considers how designers globally focus on environmentally responsible designs and the appropriate ways designers reduce material waste. This research will help understand what techniques designers can use in the name of environmentally sustainable design practices to practice waste minimization. The paper will consist of information about waste management strategies and the tools to assess the sustainable factors and explain the principles of using resources efficiently in the design stage; these factors are reviewed by describing how the designers can achieve these techniques in the design process. These factors are obtained with the help of survey responses and a literature review. Qualitative methods were used for the research. For analyzing the survey responses, descriptive analysis is chosen. This study is a step to create awareness for the designers to adopt and implement waste minimization strategies for a sustainable future
Performance of Multi-Hazard-Resistant Hollow-Core FRP-Concrete-Steel Columns with High-Strength SCC or UHPC
No full textThe Federal Highway Administration (FHWA) and state departments of transportation (DOTs) are actively promoting accelerated bridge construction (ABC) to minimize construction costs by reducing construction time, which in turn enhances work-zone safety and reduces the impact on facility users. HC-FCS columns have the potential to combine the benefits of other alternatives including significant concrete confinement, improved axial and flexural strength, and enhanced ductility and energy absorption. HC-FCS columns consist of a concrete core sandwiched between an outer fiber-reinforced polymer (FRP) tube and an inner steel tube. The FRP and steel tubes function as stay-in-place forms, with the FRP providing corrosion resistance and the steel tube providing column reinforcement and reducing congested connections. Furthermore, the concrete core provides local buckling resistance to the FRP and steel tubes. The benefits of HC-FCS columns with high-strength self-consolidating concrete (HS-SCC) or ultra-high-performance concrete (UHPC), when compared to traditional reinforced concrete (RC) columns, are unknown but will likely further reduce construction time, increase strength and ductility, and allow for thinner, lighter columns.
The main objective of this research project was to determine the improved column axial and flexural strength, ductility, and overall performance provided by HC-FCS columns when compared to traditional RC columns and to determine the benefits, or potential tradeoffs, of using HS-SCC and UHPC for the concrete core. Five half-scale column specimens were designed and constructed following AASHTO and ACI guidelines, and recommendations from previous research studies. The column specimens consisted of one RC column, two HC-FCS columns with HS-SCC used for the concrete core, and two HC-FCS columns with UHPC used for the concrete core. The specimens were subjected to displacement-controlled, cyclic lateral loading under a constant axial compressive load. The testing results of the column specimens, including the lateral load versus displacement at the column head, the peak flexural capacities, and the strain gauge data were analyzed and compared between HC-FCS column types and against the RC control column. HC-FCS columns demonstrated increased peak flexural capacity, ductility, and durability, with the UHPC cores demonstrating superior properties and performance compared to the HS-SCC cores
ScCO2-Fluids-Rock Interactions in Nanoporous Media: Applications in Enhanced Oil Recovery and Carbon Geostorage
Get PDFA global effort to reduce atmospheric CO2 levels and mitigate global warming is ongoing. Carbon capture and storage (CCS) and enhanced oil recovery (EOR) are pivotal technologies for achieving net-zero emissions, further incentivized by U.S. tax benefits. Both practices involve injecting CO2 into subsurface geological formations, where it transitions into a dense supercritical fluid phase (scCO2). Understanding interactions between scCO2, native fluids, and the subsurface formation, is crucial for optimizing EOR and managing risks in carbon geostorage (CGS). These interactions are particularly complex in nanoporous systems, such as confining zones in CGS, and during cyclic-gas injection (Huff and Puff, or HnP) in unconventional liquid-rich shale reservoirs (ULR).
This dissertation comprises two studies examining the impact of these interactions on HnP-EOR in ULR and the long-term integrity of confining zones in CGS. The first study involves over 20 HnP-EOR tests on preserved ULR samples, coupled with analytical tools to evaluate key parameters affecting crude oil and brine mobilization. Additionally, a shale oil reservoir model was developed to simulate HnP-EOR in ULR and assess net carbon efficiency. In the second study, scCO2 treatments were conducted for 21 days in five confining zones and one storage zone sample under elevated temperature and pressure (150 °F and 3000 psi). A strategy was devised to monitor geochemical reactivity at the surface level down to the micrometer depth of invasion. Before and after treatment, pore size distributions and effective matrix diffusivities were determined. ScCO2-brine-rock wettability and breakthrough tests were conducted under subsurface conditions. Following integration of these two studies with critical literature review, valuable insights into fluid recovery during HnP-EOR in ULR and the integrity of confining zones in CGS are provided
The Frankfurt Freies Jüdisches Lehrhaus’ Impact on its Prominent Jewish Thinkers: Religious Action, Responses to Modernity, and Thinking Beyond Movements
Get PDFThis thesis analyzes the works of multiple prominent figures who attended the Frankfurt Freies Jüdisches Lehrhaus in order to find recurring themes indicating a common influence of the Lehrhaus upon these figures. The first chapter discusses Lehrhaus figures considering faith motivated action in the world was a spiritual requirement of a person of faith. The second chapter observes these figures’ tendency to demonstrate dissatisfaction with modernity and a need to propose modifications on and/or progressions beyond modernity. The third chapter demonstrates these figures inclination to think outside the boundaries of the movements of their times pursuing intellectual honesty and individual thought
Study on the mechanical and thermal properties of class G cement composites
Get PDFNowadays the consumption of hydrocarbons such as oil and gas are higher than ever before, for that reason, the world is constantly looking for the development of new oil formations that were not accessible before due to the lack of technology for high-pressure and high-temperature reservoirs, being the trigger of new well construction materials that can achieve the new requirements that the industry currently needs. Simultaneously, as the oil and gas industry endeavors to satisfy this growing demand for hydrocarbons, there's a concerted effort to transition towards a more sustainable, environmentally friendly future.
For this reason, the oil and gas industry is moving to carbon-neutral alternatives to materials like cement, that is fundamental in the operation since provides well integrity, which currently has a significant carbon footprint. Cement production accounts for a substantial portion of CO2 emissions, the production of one kilogram of cement send one kilogram of CO2 to the atmosphere, contributing to approximately 9% of annual CO2 emissions produced by humans, underlining the urgency to find greener alternatives.
One of the materials that aligns with the new goals the oil and gas industry is trying to achieve regarding CO2 emissions and have the desirable characteristic to develop slurries for well cementing are geopolymers. It is a relatively cheap material that is characterized by having a high resistance to acidic environments, high compressive strength, and a low carbon footprint due to the fact is a waste material from other industrial processes.
This thesis focuses on the experimental testing and analysis of the compressive strength of neat class G cement, as well as class G cement with the addition of class F fly ash at different percentages (10%, 20% and 30% were the cement composites selected, above 30% the cement slurries were not able to be mixed, hence the study stopped at 30% fly ash by weight of cement) at both room and high temperature. Additionally, the characterization and analysis of the same class G cement composites but with the addition of sodium hydroxide to the mixture cured at high temperature. Similarly, the research aimed to experimentally test and analyze the thermal properties of neat class G cement and class G cement composites with the addition of fly ash at different percentages, cured at room temperature, to assess their thermal properties. All of the tests done in this research were conducted for a period of 28 days.
In conclusion, this research reveals that increasing the percentage of fly ash in class G cement composites directly enhances compressive strength consistently across varying environmental conditions. On the other hand, the addition of sodium hydroxide negatively impacts compressive strength by altering pH levels and hindering the formation of critical components, highlighting its adverse effect on cement properties. Finally, the results of the thermal properties were not conclusive when the Keithley 2400 meter with TPS-3 was used suggesting the need of a longer period of time for testing to ensure the stabilization of the values to finally lead to a conclusion. Whereas the results obtained using the Thermtest Portable Measurement Platform −2 concluded that the more fly ash incorporated into the class G cement sample the more is going to be the increment of the thermal conductivity, this being true up to 20% fly ash added by weight of cement. When 30% fly ash by weight of cement was added it was possible to see a slight decrease of this property
A Stylistic and Performance Analysis of Symphonia Elegiaca, op. 83 by Camil Van Hulse
Get PDFThis document provides an analysis of the second organ symphony of Camil Van Hulse: Symphonia Elegiaca, op. 83. This analysis provides a historical overview, an examination of programmatic content, and a compositional analysis of each of the five movements of Symphonia Elegiaca. Additionally, a biography of Camil Van Hulse and a chronological catalog of his published compositions for solo organ are included.
Chapter One defines the purpose, need, limitations, organization of the study, and provides a summary of related literature on Camil Van Hulse’s organ symphonies, including biographical materials relating to Van Hulse and literature related to the organ symphony. Chapter Two provides a biographical sketch of Camil Van Hulse, detailing his life and notable achievements. Chapter Three provides historical context related to Symphonia Elegiaca. Chapters Four, Five, Six, Seven, and Eight contain an analysis of each of the five movements of Symphonia Elegiaca, op. 83. Each chapter provides a historical overview and a compositional analysis. Chapter Nine is a conclusion and summary of the findings of this study. By exploring Symphonia Elegiaca by Camil Van Hulse, this study recognizes the significance of Van Hulse’s contributions to the organ repertoire and musical life in the United States and Belgium
Development of Contrast Agents for Optoacoustic Imaging
No full textOptoacoustic imaging is an emerging modality with inherent advantages relevant for clinical use. Following excitation of optoacoustic contrast agents with ultrashort (~10 ns) pulses of near-infrared light, thermoelastic contractions and expansions of the molecule are produced and detected as acoustic waves. As the pathlength of light is reduced by half, and since near-infrared light penetrates efficiently in biological tissue, the influence of the imaging depth/spatial resolution tradeoff is significantly diminished; an unavoidable phenomenon in traditional optical imaging. Multiwavelength illumination allows for understanding of optoacoustic signal as a function of excitation wavelength, which can be utilized in unmixing algorithms, a feature that is unavailable with conventional ultrasound. Such unmixing algorithms have the ability to separate and determine the location and concentration of multiple optoacoustic agents in an unknown sample. There is a need for developing improved optoacoustic contrast agents and delivery mechanisms to further increase the applications of optoacoustic imaging. In this dissertation, newly synthesized squaraine and cyanine compounds are extensively characterized to determine how molecular structure directly impacts the ability to generate optoacoustic signal. Specifically, which molecular features result in changes to optoacoustic intensity and spectral shape, e.g., optoacoustic signal vs. wavelength. These studies show that through heavy halogenation, addition of rotatable bonds, and functionalization with diethylamino groups positively impact the strength of the contrast agents and may result in bathochromic shifts. Further, mesoporous silica nanoparticles have shown potential for inert, high cargo, and tunable delivery agents, that will not impact optoacoustic imaging due to the silica base. However, silica nanoparticles have previously been linked to toxicity, along with commonly used silica gatekeeping coatings. After toxicity evaluation of commonly used coatings on silica nanoparticles, chitosan was deemed nontoxic and shows potential as a pH-responsive coating on silica nanoparticles. Overall, nanoparticles have struggled in clinical settings such as cancer, due to poor understanding on how to improve tumor specificity. Optoacoustic imaging was utilized to visualize actively and passively targeted mesoporous silica nanoparticles of various size. Our results strongly suggest that 25-50 nm silica nanoparticles coated with chitosan and actively targeted with pH low insertion peptides significantly improve tumor specificity in an orthotopic model of pancreatic cancer. This data represents tools and guidelines to follow in the creation of optoacoustic contrast agents and delivery mechanisms to specifically target biological processes, such as pancreatic cancer. In addition, these results suggest future opportunities to improve optoacoustic imaging applications
DeepWiN: Deep Graph Reinforcement Learning for User-Centric Radio Access Networks Automation
Get PDFThe future cellular networks are expected to support an increasing number of users with heterogeneous applications, requiring varying network resources. Therefore, the 6G and beyond cellular networks need to be elastic, and user-centric. User-centric Radio Access Networks (UCRAN), with virtual cells (S-zones), can provide on-demand connectivity, coverage and quality of service to different user applications while optimizing the network for energy efficiency, area spectral efficiency, reliability and user service rate. However, with high variability in the network, due to user mobility and fading, the selection of S-zone sizes which optimize the network performance for multiple types of users simultaneously becomes a challenge. Therefore, to automate the selection of S-zone sizes dynamically, we propose deep graph reinforcement learning (DGRL), a Soft actor-critic model integrated with Graph neural network. DGRL infers from DeepWiN, a graphical representation of UCRAN that encodes the non-euclidean topology of the network along with its euclidean features, effectively encapsulating the wireless domain knowledge of the network configuration. Our experiments show that the deep graph reinforcement learning can learn to optimize S-zone sizes with 15% fewer training episodes in comparison to the legacy neural-network-based reinforcement learning, hence demonstrating the advantage of network topology-awareness for artificial intelligence