Engineering Commons^™

Additive And Interface Engineering Of Lead-Tin Mixed Low-Bandgap Perovskite Solar Cells For Higher Efficiency And Improved Stability, Nabin Ghimire

Electronic Theses and Dissertations

Lead (Pb) -Tin (Sn) mixed perovskites suffer from large open-circuit voltage (VOC) loss due to the rapid crystallization of perovskite film, creating Sn and Pb vacancies. Such vacancies act as defect sites expediting charge carrier recombination, thus hampering the charge carrier dynamics and optoelectronic properties of perovskite films. In the first project, we focused on the passivation of perovskite surface defects to increase the opencircuit voltage of the 1.25 eV low-bandgap perovskite solar cells by utilizing a trace amount of Phenethylammonium iodide (PEAI) in the perovskite precursor solution as a doping agent. The incorporation of PEAI in perovskite precursors improved …

Bio-Inspired Materials For Electrochemical Sensors, Matthew Joseph Hummel

Electronic Theses and Dissertations

Electrochemical biosensors are a rapidly growing research area that has greatly improved its specificity, accuracy, and precision in the detection of biomolecules in contemporary literature and industry alike. Typically, these systems exist in a three-electrode conformation with a working electrode functioning as the anode, a counter electrode functioning as the cathode, and a reference electrode allowing for the control of potential in the system. The method by which these sensors work is through the sharing of electrons via redox reactions with the target molecule and the working electrode or modifications on its surface. By exploiting the function of biomaterials that …

Computational Modeling Of Climate Attributes And Condition Deterioration Of Concrete Highway Pavements, Salma Sultana

Electronic Theses and Dissertations

An efficient and safe road network secures the nation’s economy and prosperity by providing public mobility and freight transport. Maintenance and rehabilitation of the road network cost billions of dollars annually. Road and highway infrastructures performance in any country is impacted by load repetitions and it is further compromised by climate attributes and extreme weather events. Damages to roads and bridges are among the infrastructure failures that have occurred during these extreme events. If maintenance and rehabilitation are not done promptly, the damages to the road caused by heavy traffic and extreme climate may lead to life-threatening conditions for road …

Convective Heat Transfer Enhancement Of A Channel-Flow Using Synthetic Jet, Pravesh Pokharel

Electronic Theses and Dissertations

A transient numerical simulation was carried out using ANSYS Fluent, to investigate the convection heat transfer enhancement of the air channel flow using the synthetic jet. Keeping the dimensional parameters of the domain fixed, averaged channel flow velocity was varied up to 3m/s. The diaphragm displacement effect on synthetic jet was studied, ranging the peak-to-peak displacement value from 0.4 to 1.2mm with increment of 0.4mm. Three locations were studied to determine the best operating location of the synthetic jet. Also, frequencies were varied up to 200Hz with every 50Hz increment, from initial condition of 50Hz. It was found that the …

Dachash: A Dynamic, Cache-Aware And Concurrent Hash Table On Gpus, Hao Zhou

Electronic Theses and Dissertations

GPU acceleration of hash tables in high-volume transaction applications such as computational geometry and bio-informatics are emerging. Recently, several hash table designs have been proposed on GPUs, but our analysis shows that they still do not adequately factor in several important aspects of a GPU’s execution environment, leaving large room forfurther optimization.

Forecasting Geotechnical Parameters From Electrical Resistivity And Seismic Wave Velocities Using Artificial Neural Network Models, Fatema Tuz Johora

Electronic Theses and Dissertations

Geotechnical measurements of soil parameters used in the design of infrastructure provide information at a specific point of the ground. The use of limited point data may result in greater uncertainty and less reliability in design. Geophysical methods are non-invasive, less time-consuming, and provide continuous spatial information about the soil. However, geophysical information is not in terms of engineering parameters. Correlations between geotechnical parameters and geophysical parameters are needed to facilitate the use of geophysical information in geotechnical designs. The current research is focused on two geophysical methods; electrical resistivity (ER) and seismic wave velocity (S-wave and P-wave). Artificial neural …

Development Of Bio-Based Nanocomposites For Biosensor And Indicator Applications In Smart Food Packaging, Abdus Sobhan

Electronic Theses and Dissertations

Smart food packaging based on biosensors has been attracting more and more interest to the industrial community because of the concerns of food quality and safety. A food packaging with biosensor has a scope to enable real-time monitoring of microbial breakdown products of packaged foods. Furthermore, one of the biggest challenges in implementing biosensor for smart packaging materials is the development of bio-sensing active materials that can leverage their electrical, thermal, biodegradable and other functional properties. In this regard, nanocellulose-based activated carbon (NAC) nanocomposite was developed using the activated carbon and nanocellulose gel using the casting method with their different …

A Hydrologic Study Of Climate Variability In Arid Region, Abdullah Alzaydani

Electronic Theses and Dissertations

Climate variability is an important subject to study. It is the change of climate over a long time, which could have a positive or negative impact on humans, soil, and wildlife. Many environments, such as arid environment could be affected by climate variability. The research goal is studying and examining climate variability in arid environment. The research includes three different studies. The first study includes reviewing and understanding of climate variability over extended time through existing studies in arid environments. In addition, this study includes knowledge about climate negative or positive impact on the environment. This study will be reviewing …

Development Of Efficient Wide-Bandgap Perovskite Solar Cells With Composition And Interface Engineering, Khan Mamun Reza

Electronic Theses and Dissertations

Metal halide perovskites are considered the most promising solar energy technology because of their distinct properties, such as defect tolerance, low cost, easy fabrication due to solution-processibility, band tunability, etc. Due to these properties, the efficiency of perovskite solar cells reaches more than 25% and approaches the limit of singlejunction within last few years. To increase the efficiency further in a more cost-effective way, double junction tandem solar cells with an efficient ‘top’ wide-bandgap cell is desired. But wide-bandgap perovskites still face some critical issues, such as poor morphology, smaller grain size, the formation of excessive lead halides, light-induced halide …

A Novel Approach Toward High Accuracy Indoor Localization}{Masters Of Science, Yunshu Wang

Electronic Theses and Dissertations

This thesis presents a novel approach towards high accuracy indoor localization with smartphones. Better than all the existing indoor localization methods, our approach has the advantage of being infrastructural-free, robust, and it does not require any pre-installation in a new environment. To make this goal come true, we built a testbed that only uses the Inertial Measurement Units (IMU) of the smartphones to access the smartphones' raw acceleration and orientation data, then use these data to calculate the user's location by coordinate transformation and interactions. We conducted extensive experiments and evaluations for testbed validation as well as to carefully examine …

Analysis Of Bundle Protocol With Turbo Code, Babita Pradhan

Electronic Theses and Dissertations

Bundle protocol is one of the main protocols for data transfer in delay/disruption networking characterized by the long delay, frequent disruption, intermittent connectivity, andhigh error rates. Using a store and forward technique, bundle protocol stores the application data by dividing it into smaller bundles locally at each node and then forwards it to the next node when access is available. Usually, it operates as an overlay network by staying on top of any other networking architecture. As one of the main protocols for delay/disruption networking, many studies have analyzed its performance. This thesis analyzes the bundle protocol’s performance in terms …

Electromagnetic Survey Design Using Artifical Neural Networks, Shariful Islam Sharif

Electronic Theses and Dissertations

Acquiring geophysical information requires selection of the geophysical method based upon the defining physical property and a survey design with adequate resolution but cost effective based upon the size of the area to be surveyed. The objective of this study is to use artificial neural nets (ANNs) to design an optimal survey. The developed approach is tested for the case of soil pipe surveying using electromagnetics. Soil pipes are tortuous voids located within 1.5 m depth of the ground surface. They trend perpendicular to the slope and have cross-sectional dimensions on the order of millimeters to tens of centimeters. The …

Nonreciprocity Applications In Acoustics And Microfluidic Systems, Masoud Naghdi

Electronic Theses and Dissertations

Breaking reciprocity in linear acoustic systems and designing a novel actuator for the nonreciprocal valveless pumps are studied in this dissertation. The first part was started by deriving the acoustic governing equations in a moving wave propagation medium. It was shown thatthe Coriolis acceleration term appears ina cross-product term with the wave vector. It means the main reason for breaking reciprocity in the circular fluid flow is the Coriolis acceleration term. Finally, the governing equations were solved numerically by COMSOL Multiphysics software. Moreover, Green`s second identity was used as a complimentary method to prove breaking reciprocityin such a system with …

Image Analysis Of Colloidal Systems For Pair And Triplet Correlations., Brianna Price

Electronic Theses and Dissertations

Interactions among colloidal particles drive stability of suspensions or the assembly of particles into larger superstructures such as agglomerates or crystals. Typically, colloidal interactions are modeled using pairwise interaction potential energies which consider the interactions between pairs of particles. However, additional particles can modulate pair potentials, leading models to predict incorrect behavior. To analyze the effects of three-body interactions on the structuring of colloidal systems, pair and triplet correlation functions are calculated from published experimental data. These correlation functions are then translated into empirical pair and triplet potentials of mean force, which are then used to model systems more accurately …

Tibial Strains And Tray-Bone Micromotions After Total Knee Arthroplasty: Computational Studies Evaluating The Tibial Fixation, Huizhou Yang

Electronic Theses and Dissertations

Cemented and cementless fixation in total knee arthroplasty (TKA) have been successfully used for decades. As the number of younger and more active patients treated with TKA continues to increase, long-term implant survivorship is of increasing importance. One of the most common complications and hence the reason for revision is mechanical loosening (23.1% of all revised TKA). The loosening mechanisms have been proposed for different fixation types. For cemented fixation, bone remodeling after surgery is regulated by the changes in strain energy density (SED). The recruitment of osteoclasts and osteoblasts is controlled by SED-related signals. Insufficient stimuli can promote bone …

Development Of Triangular And Tetrahedral Finite Elements For Solutions To Thermoelastic Instabilities Using Hotspotter, Cortney Samuel Leneave

Electronic Theses and Dissertations

The objective of the work presented in this thesis is to develop first-order triangular and tetrahedral elements for solutions to Thermoelastic Instabilities (TEI) regarding sliding friction systems in Hotspotter.

Hotspotter software uses a finite element method and an eigenvalue method and is an important tool because currently no other commercial software exists which solves the TEI problem for critical velocities and wave numbers of a system. Hotspotter currently uses quadrilateral and hexahedral elements for two and three dimensional analysis, respectively. Typically, tri and tet elements are used in industry when doing static and dynamic stress analysis. Therefore, the Hotspotter user …

Accurate Measurement Of Healthy Joint Kinematics To Inform Diagnosis And Treatment, Vasiliki Kefala

Electronic Theses and Dissertations

The description of human motion has a primary importance in different scientific areas such as medicine, sports, physical therapy. Kinematics specifically studies pure motion without reference to the causes of motion such as forces. Understanding the kinematics of human movement is of critical importance in medicine and biology. Motion measure­ment can be used in order to to evaluate functional performance of limbs under normal and abnormal conditions. Kinematic knowledge is also important for diagnosis and surgi­cal treatment of joint disease and the design of implants to rehabilitate function. Accurate joint kinematics is essential to protect articular functionality. An alteration may …

Dislocation Mechanics Of Total Hip Arthroplasty: A Combined Experimental And Computational Analysis, Michael Scinto

Electronic Theses and Dissertations

While total hip arthroplasty is considered a successful procedure, dislocation remains a serious complication as recurrent dislocations may require additional surgeries. Knowledge on dislocation events as they occur in vivo are limited, therefore researchers rely on experimental and computational methods. A custom MATLAB script and an experimental procedure utilizing a six-degree of freedom actuator were developed to further understand how various surgical considerations affect dislocation mechanics in total hip arthroplasty. Computationally, it was determined that impingement free range of motion is limited during internal rotation in flexion and during external rotation in extension. Experimentally, our results suggest that the posterior …

Quantification Of Climate Variability And Extreme Events In The Great Plains, Angelinah Ntsieng Rasoeu

Electronic Theses and Dissertations

Climate variability and extreme events continue to worsen resulting in significant impacts to society and the environment. Quantifying precipitation variability, streamflow, and extreme events at local scale is crucial for local planning and management due to spatial and temporal precipitation variability which influences streamflow and thus, water resources. This study uses statistical tools to analyze 1895-2019 (125 years) of historical precipitation data to examine how long-term precipitation varies annually, seasonally, and monthly, and create climate classifications. The results show that annual precipitation is increasing linearly over time ranging from 13.2 in (1976) to 43.1 in (2010) and 5 climate classes …

Lightweight Encryption Based Security Package For Wireless Body Area Network, Sangwon Shin

Electronic Theses and Dissertations

As the demand of individual health monitoring rose, Wireless Body Area Networks (WBAN) are becoming highly distinctive within health applications. Nowadays, WBAN is much easier to access then what it used to be. However, due to WBAN’s limitation, properly sophisticated security protocols do not exist. As WBAN devices deal with sensitive data and could be used as a threat to the owner of the data or their family, securing individual devices is highly important. Despite the importance in securing data, existing WBAN security methods are focused on providing light weight security methods. This led to most security methods for WBAN …

Assessing The Effectiveness Of Cfd To Solve An Inverse Problem Of Thermal Profiles For The Protodune-Sp Neutrino Detector, Cecilia Anne Streff

Electronic Theses and Dissertations

Computational fluid dynamics (CFD) is a branch of fluid mechanics which is employed to numerically solve complex fluid, heat transfer, and multiphysics problems. Traditionally, CFD techniques are used to solve “forward” problems—using some known information of a system as inputs to a representative model to predict experimental measurements or expected system behavior. The work presented here demonstrates how CFD may be used to solve an “inverse” problem—given limited experimental data and some model, predict (previously unidentified) “input” system (or system model) parameters. The case study for this research uses a validated CFD modeling approach of the liquid argon (LAr) region …

Evaluating And Predicting The Risk Of Algal Blooms In A Freshwater Lake Through A 4-Dimensional Approach: A Case Study On Lake Mitchell, Sumit Kumar Ghosh

Electronic Theses and Dissertations

Excessive algal growth in freshwater lakes can negatively impact ecosystems, recreation, and human health. Though algae are a natural part of freshwater ecosystems, elevated nutrient loading from anthropogenic and natural sources can lead to algal blooms. Both algae and blue-green algae (BGA) are responsible for algal blooms; however, BGA (cyanobacteria) is more dangerous. The first objective of this research was to prepare a conceptual model to understand how various environmental variables affect algae. This conceptual model was used to choose the environmental variables that help increase or decrease algae in the water environment. The second objective was to develop empirical …

An Accuracy And Precision Analysis Of The Velys™ Robotic Assisted Solution For Total Knee Arthroplasty, Gary Doan

Electronic Theses and Dissertations

Total knee arthroplasty (TKA) is a procedure where the arthritic surfaces of the knee is removed and replaced with a combination of metal and polymer implants that recreates the joint line to restore function and quality of life. Implant alignment is important in the success of a TKA. Modern day conventional instrumentation can be cumbersome in the operating room and can be inaccurate when resecting bone and aligning implants. Patients with large errors in resections and implant orientation are more prone to experience mechanical failures with their TKA. Mechanical failures in primary TKA require revision surgeries which can lead to …

Broadening The Capability Of Kinetics Analysis In Biomechanics, Nicholas Nelson

Electronic Theses and Dissertations

Two studies are discussed in this manuscript each preceded by a literature review of the topic. The first review and study explore agility movements and the effect that alternative upper designs in shoes might have on ground reaction force measures of performance. The second review and study evaluate methods of predicting ground reaction forces without the use of a force platform. A method of using effective forces and ways of improving its accuracy are evaluated in depth.

Inter-Annual To Inter-Decadal Spatiotemporal Effects Of Storm And Nourishment Events In North Myrtle Beach, South Carolina, Christina Mary Boyce

Electronic Theses and Dissertations

No abstract provided.

The Use Of Nanoparticles And Electrospun Fibers For Intravaginal Delivery To Treat Viral And Bacterial Infections And Electrophysiological Measurements Of Synthetic Chloride Channels., Farnaz Minooei

Electronic Theses and Dissertations

Female reproductive viral and bacterial infections affect millions of women worldwide. Given the diversity and magnitude of these unmet reproductive health challenges, topical administration of antiretrovirals (ARVs) and antibiotics have emerged as promising approaches to maintain and restore reproductive health. However, currently available intravaginal dosage forms often suffer from low user adherence and the need for frequent, daily administration to achieve therapeutic effect. To address these challenges, the broad goal of this research was to focus on the development of new localized nanoparticle (NP) and electrospun fiber dosage forms to prolong the delivery and enhance the efficacy of active agents …

Impacts Of Environmental And Hydrologic Factors On Urban Stream Water Quality., Jason Patrik Ingram

Electronic Theses and Dissertations

Urban streams can be impacted by a multitude of hydrologic and environmental factors, making maintaining these water sources difficult. Urbanization can exacerbate these impacts creating new challenges in preserving suitable urban stream water quality. Urbanization is the development of city landscape and suburban living within an otherwise natural region. For this environmental impact study, the effects of city development on urban stream water quality was monitored for Mill Creek in Louisville, Kentucky. To study the effects of urbanization on Mill Creek, this project was completed utilizing the BACI method for comparing impacts. The results of the water quality monitoring were …

Automatic Target Recognition With Convolutional Neural Networks., Nada Baili

Electronic Theses and Dissertations

Automatic Target Recognition (ATR) characterizes the ability for an algorithm or device to identify targets or other objects based on data obtained from sensors, being commonly thermal. ATR is an important technology for both civilian and military computer vision applications. However, the current level of performance that is available is largely deficient compared to the requirements. This is mainly due to the difficulty of acquiring targets in realistic environments, and also to limitations of the distribution of classified data to the academic community for research purposes. This thesis proposes to solve the ATR task using Convolutional Neural Networks (CNN). We …

Imparting 3d Representations To Artificial Intelligence For A Full Assessment Of Pressure Injuries., Sofia Zahia

Electronic Theses and Dissertations

During recent decades, researches have shown great interest to machine learning techniques in order to extract meaningful information from the large amount of data being collected each day. Especially in the medical field, images play a significant role in the detection of several health issues. Hence, medical image analysis remarkably participates in the diagnosis process and it is considered a suitable environment to interact with the technology of intelligent systems. Deep Learning (DL) has recently captured the interest of researchers as it has proven to be efficient in detecting underlying features in the data and outperformed the classical machine learning …

Fly-In Visualization Of Tubular Objects: Theory And Application In Virtual Colonoscopy., Mostafa Mohamed

Electronic Theses and Dissertations

In this dissertation, visualization for tubular objects, i.e., projecting 2D images from 3D inner surfaces of tubular objects, is investigated. Given surface points on 3D objects, an approach that most accurately and effectively projects 2D images from the 3D surface with minimal loss of information is desired. A new visualization method for tubular surfaces is proposed, denoted by "Fly-In". The approach uses a virtual camera ring that moves along the inner surface's centerline, obtaining projections of the surrounding views, forming small 3D topological rings within the tube rendered as a 2D rectangular image. A new visualization loss measure is also …