Engineering Commons^™

Fabrication Of Binder-Free Electrodes Based On Graphene Oxide With Cnt For Decrease Of Resistance, Di Zhang

Masters Theses

In electrode double layer capacitor (EDLC), electrodes usually contain binder materials to provide adhesion between electrode materials. However, binder materials usually bring unwanted resistances to the component due to their non-conductivity properties and the occupation of ion cavities. The purpose of this thesis is to demonstrate the feasibility of fabricating electrodes for EDLCs by using carbon nanotubes (CNTs) and graphene oxide (GO) without using any binding materials. At the same time, investigating the binder-free electrode’s electrochemical properties and make an assumption of its potential application in the future.

The slurry of binder-free electrodes was fabricated by ultrasonicating water suspended CNTs …

Real-Time Tddft-Based Filtered Spectroscopy, Ivan Williams

Masters Theses

We demonstrate the ability to simulate targeted excitation of atomistic systems using our real-time TDDFT-based simulation framework NESSIE. Traditional ap- proaches for extracting spectra through real-time TDDFT involves excitation of all frequencies via impulse requiring long simulation times and yielding poor resolution. By exciting the system with a modulated sinc pulse between the frequencies of inter- est we are able to obtain a spectral response with far more precision in a significantly shorter time frame than competing implementations.

Optimal Mammography Schedule Estimates Under Varying Disease Burden, Infrastructure Availability, And Other Cause Mortality: A Comparative Analyses Of Six Low- And Middle- Income Countries, Shifali Shifali

Masters Theses

Low-and-middle-income countries (LMICs) have a higher mortality-to-incidence ratio for breast cancer compared to high-income countries (HICs) because of late-stage diagnosis. Mammography screening is recommended for early diagnosis, however, current screening guidelines are only generalized by economic disparities, and are based on extrapolation of data from randomized controlled trials in HICs, which have different disease burdens and all-cause mortality compared to LMICs. Moreover, the infrastructure capacity in LMICs is far below that needed for adopting current screening guidelines. This study analyzes the impact of disease burden, infrastructure availability, and other cause mortality on optimal mammography screening schedules for LMICs. Further, these …

Network Virtualization And Emulation Using Docker, Openvswitch And Mininet-Based Link Emulation, Narendra Prabhu

Masters Theses

With the advent of virtualization and artificial intelligence, research on networked systems has progressed substantially. As the technology progresses, we expect a boom in not only the systems research but also in the network of systems domain. It is paramount that we understand and develop methodologies to connect and communicate among the plethora of devices and systems that exist today. One such area is mobile ad-hoc and space communication, which further complicates the task of networking due to myriad of environmental and physical conditions. Developing and testing such systems is an important step considering the large investment required to build …

Metric Learning Via Linear Embeddings For Human Motion Recognition, Byoungdoo Kong

Masters Theses

We consider the application of Few-Shot Learning (FSL) and dimensionality reduction to the problem of human motion recognition (HMR). The structure of human motion has unique characteristics such as its dynamic and high-dimensional nature. Recent research on human motion recognition uses deep neural networks with multiple layers. Most importantly, large datasets will need to be collected to use such networks to analyze human motion. This process is both time-consuming and expensive since a large motion capture database must be collected and labeled. Despite significant progress having been made in human motion recognition, state-of-the-art algorithms still misclassify actions because of characteristics …

Nozzle Clogging Prevention And Analysis In Cold Spray, Alden Foelsche

Masters Theses

Cold spray is an additive manufacturing method in which powder particles are accelerated through a supersonic nozzle and impinged upon a nearby substrate, provided they reach their so-called critical velocity. True to its name, the cold spray process employs lower particle temperatures than other thermal spray processes while the particle velocities are comparably high. Because bonding occurs mostly in the solid state and at high speeds, cold spray deposits are distinguished for having low porosity and low residual stresses which nearly match those of the bulk material.

One complication with the cold spray process is the tendency for nozzles to …

A Study On Latent Thermal Energy Storage (Ltes) Using Phase Change Materials (Pcms) 2020, Ritvij Dixit

Masters Theses

The significant increase in energy requirements across the world, provides several opportunities for innovative methods to be developed to facilitate the storage and utilization of energy. The major energy demand is in the form of electrical energy for domestic as well as industrial sectors, a large part of which are the heating and cooling requirements. Appropriate utilization of thermal energy storage can effectively aid in reducing the electrical demand by storage and release of this thermal energy during peak hours.

Thermal Energy Storage using Phase Change Materials (PCMs) is an attractive method of energy storage, with a wide variety of …

Considerations For The Design Optimization Of Floating Offshore Wind Turbine Blades, Evan M. Gaertner

Doctoral Dissertations

Floating offshore wind turbines are an immature technology with relatively high costs and risk associated with deployment. Of the few floating wind turbine prototypes and demonstration projects deployed in real metocean conditions, all have used standard turbines design for onshore or offshore fixed bottom conditions. This neglects the unique unsteady aerodynamics brought on by floating support structure motion. While the floating platform has been designed and optimized for a given rotor, the global system is suboptimal due to the rotor operating in conditions outside of which it was design for. If the potential offered by floating wind turbines is to …

Improving Drivers’ Behaviour When Partial Driving Automation Fails, Yalda Ebadi

Doctoral Dissertations

With the advent of automated vehicle systems, the role of drivers has changed to a more supervisory role. However, it is known that all vehicles with Level 2 (L2) systems have a very specific operational design domain (ODD) and can only function on limited conditions. Hence, it is important for drivers to perceive the situations properly and regain the control from the L2 system when needed. As suggested by past research, designing an informative interface could help drivers in their new supervision and intervention role while driving with L2 vehicles by providing feedback to drivers when hazards or event that …

Engineering Stimuli-Responsive Polymeric Nanoassemblies: Rational Designs For Intracellular Delivery Of Biologics, Kingshuk Dutta

Doctoral Dissertations

Biologic drugs have gained enormous research attention in recent years as reflected by the development of multiple candidates to the clinical pipelines and an increased percentage of FDA approval. This is reasoned by the fact that biologics have been proven to deliver more predictive and promising benefits for many hard-to-cure diseases by ‘drugging the undruggable’ targets. However, the challenges associated with biologic drug development are multi-fold, viz, poor encapsulation efficacy, systemic instability, low cellular internalization and endosomal escape capability. Thus, it is essential to develop new molecular strategies that can not only address the associated drug delivery challenges, but also …

Experimental Study Of Viscoelastic Fluid-Structure Interactions, Anita Anup Dey

Doctoral Dissertations

It is well known that when a flexible or flexibly-mounted structure is placed perpendicular to a Newtonian fluid flow, it can oscillate due to the shedding of vortices at high Reynolds numbers. Unlike Newtonian fluids, viscoelastic fluid flow can become unstable even at infinitesimal Reynolds numbers due to a purely elastic flow instability occurring at large Weissenberg numbers. This thesis focuses on exploring the mechanisms of viscoelastic fluid-structure interactions (VFSI) through experimental investigations on several different combinations of flexible and flexibly-mounted circular cylinders, micro and macro-scale cantilevered beams and viscoelastic fluids such as wormlike micelle solutions and polymer solutions. VFSI …

Encapsulation And Stabilization Of Biomacromolecules, Whitney Blocher Blocher Mctigue

Doctoral Dissertations

Recent work in the area of protein encapsulation has turned away from traditional methods of sequestration toward gentler, purely aqueous techniques. Among them, complex coacervation has become a topic of discussion. Complex coacervation is an all-aqueous liquid-liquid phase separation phenomenon dominated by electrostatic interactions and entropic gains. The use of coacervates as protein encapsulants has garnered much attention, but there has been little headway in determining a set of design rules. We considered coacervation between two oppositely-charged polypeptides and a biomacromolecule cargo to investigate the effects of changing aspects of the coacervating polymers and/or various solution parameters. We characterized the …

Theory And Improved Methods For Probing The Cavitation To Fracture Transition, Christopher Barney

Doctoral Dissertations

A material is considered soft when its bulk modulus is significantly greater than its shear modulus. Rubbery polymers are a class of soft materials where resistance to extension is mainly entropic in nature. Polymeric soft solids differ from liquids due to the presence of a percolated network of strong bonds that resist deformation and flow on a given time scale. The incompressible nature, entropically driven elasticity, and molecular scale network structure of soft polymeric solids combine to impart unique mechanical behavior that often results in complex material responses to simple loading situations. An important example of this is cavitation in …

Investigating The Role Of Iron In The Photogranulation Phenomenon, Abeera Ayaz Ansari

Doctoral Dissertations

Oxygenic photogranules (OPGs) are dense spherical microbial aggregates that are used for self-aerating wastewater treatment. Filamentous cyanobacteria are key granulating species, providing structural backbone and integrity in OPGs. Currently, the mechanisms for selecting filamentous cyanobacteria and their ability to form spherical OPGs are not well understood. Literature shows that iron (Fe) availability plays a significant role in the cyanobacterial growth and colony formation. Moreover, Fe availability is known to be dependent upon light, which is an essential growth substrate for the phototrophs. This research has investigated the role of Fe in the photogranulation phenomenon and the impact of light intensity …

Controlled Membrane Remodeling By Nanospheres And Nanorods: Experiments Targeting The Design Principles For Membrane-Based Materials, Sarah Zuraw-Weston

Doctoral Dissertations

In this thesis we explore two experimental systems probing the interactions of nanoparticles with lipid bilayer membranes. Inspired by the ability of cell membranes to alter their shape in response to bound particles, we report two experimental studies: one of nanospheres the other of long, slender nano-rods binding to lipid bilayer vesicles and altering the membrane shape. Our work illuminates the role of particle geometry, particle concentration, adhesion strength and membrane tension in how membrane morphology is determined. We combine giant unilamellar vesicles with oppositely charged nanoparticles, carefully tuning adhesion strength, membrane tension and particle concentration. In the case of …

System Design And Implementation For Hybrid Network Function Virtualization, Xuzhi Zhang

Doctoral Dissertations

With the application of virtualization technology in computer networks, many new research areas and techniques have been explored, such as network function virtualization (NFV). A significant benefit of virtualization is that it reduces the cost of a network system and increases its flexibility. Due to the increasing complexity of the network environment and constantly improving network scale and bandwidth, it is imperative to aim for higher performance, extensibility, and flexibility in the future network systems. In this dissertation, hybrid NFV platforms applying virtualization technology are proposed. We further explore the techniques used to improve the performance, scalability and resilience of …

Performance Evaluation Of Classical And Quantum Communication Systems, Gayane Vardoyan

Doctoral Dissertations

The Transmission Control Protocol (TCP) is a robust and reliable method used to transport data across a network. Many variants of TCP exist, e.g., Scalable TCP, CUBIC, and H-TCP. While some of them have been studied from empirical and theoretical perspectives, others have been less amenable to a thorough mathematical analysis. Moreover, some of the more popular variants had not been analyzed in the context of the high-speed environments for which they were designed. To address this issue, we develop a generalized modeling technique for TCP congestion control under the assumption of high bandwidth-delay product. In a separate contribution, we …

Micro-Physiological Models To Mimic Mucosal Barrier Complexity Of The Human Intestine In Vitro, Abhinav Sharma

Doctoral Dissertations

The mucosal barrier in the intestine is vital to maintain selective absorption of nutrients while protecting internal tissues and maintaining symbiotic relationship with luminal microbiota. This bio-barrier consists of a cellular epithelial barrier and an acellular mucus barrier. Secreted mucus regulates barrier function via in situ biochemical and biophysical interaction with luminal content that continually evolves during digestion and absorption. Increasing evidence suggests that a mucus barrier is indispensable to maintain homeostasis in the gastrointestinal tract. However, the importance of mucus barrier is largely underrated for in vitro mucosal tissue modeling. The major gap is the lack of experimental material …

Engineering Mesothelin-Binding Proteins As Targeted Cancer Diagnostics And Therapeutics, Allison Rita Sirois

Doctoral Dissertations

Cancer is a significant global health concern; and traditional therapies, including chemotherapeutics, are often simultaneously toxic yet ineffective. There is a critical need to develop targeted cancer therapeutics which specifically inhibit molecules or molecular pathways essential for tumor growth and maintenance. Furthermore, a targeted therapy is only effective when a patient's tumor expresses the molecular target; therefore, companion diagnostics, including molecular imaging agents, are a necessary counterpart of targeted therapies. Mesothelin (MSLN) is a cell surface protein overexpressed in numerous cancers, including triple-negative breast, pancreatic, ovarian, liver, and lung, with limited expression in normal tissues. Aberrant MSLN expression promotes tumor …

Robust And Sustainable Energy Pathways To Reach Mexico’S Climate Goals, Rodrigo Mercado Fernandez

Doctoral Dissertations

As countries set climate change goals for adaptation and mitigation efforts, there are many questions regarding to how to reach these targets. These efforts will necessitate the transition of our electricity infrastructure from relying on conventional electricity generation technologies including natural gas, coal and oil, to clean energy generation with renewables. Through the three essays presented in this dissertation, we explore various pathways of development for the electricity system to reach long term climate change goals. We are interested in identifying: Is there a unique optimal development option or are there various? How do different mixes of electricity generation technologies …

Market-Conscious Strategies To Improve The Performance And Stability Of Planar, P-I-N Hybrid Organic-Inorganic Metal Halide Perovskite Solar Cells, Brandon Dunham

Doctoral Dissertations

Planar, p-i-n (inverted) hybrid organic-inorganic perovskite solar cells that use low-temperature, solution-processable charge-transport layers have garnered much attention due to their direct compatibility with flexible substrates and cost-effective roll-to-roll manufacturing. Nevertheless, this architecture has failed to repeatedly achieve the superior power conversion efficiencies frequently attained by its n-i-p counterpart. Additionally, the perovskite active layer has poor stability in the presence of prolonged light exposure, high temperatures, and moisture. In this study, we propose commercially viable strategies to improve the performance and stability of inverted methylammonium lead iodide perovskite solar cells. First, we show that a simple two-step method comprising evaporation-induced …

Perception System: Object And Landmark Detection For Visually Impaired Users, Chenguang Zhang

Masters Theses

This paper introduces a system which enables visually impaired users to detect objects and landmarks within the line of sight. The system works in two modes: landmark mode, which detects predefined landmarks, and object mode, which detects objects for everyday use. Users can get audio announcement for the name of the detected object or landmark as well as its estimated distances. Landmark detection helps visually impaired users explore an unfamiliar environment and build a mental map.

The proposed system utilizes a deep learning system for detection, which is deployed on the mobile phone and optimized to run in real-time. Unlike …

Short Term Energy Forecasting For A Microgird Load Using Lstm Rnn, Akhil Soman

Masters Theses

Decentralization of the electric grid can increase resiliency (during natural disasters) and can reduce T&D energy losses and emissions. Microgrids and DERs can enable this to happen. It is important to optimally control microgrids and DERs to extract the greatest economic, environmental and resiliency benefits. This is enabled by robust forecasting to optimally control loads and energy sources. An integral part of microgrid control is power side and load side demand forecasting.

In this thesis, we look at the ability of a powerful neural network algorithm to forecast the load side demand for a microgrid using the UMass campus as …

Optimization Of Thermal Energy Storage Sizing Using Thermodynamic Analysis, Andrew Villanueva

Masters Theses

The aim of this thesis is to examine the effect that Thermal Energy Storage (TES) sizing has on a building’s ability to meet heating and cooling demands in an energy and cost efficient manner. The focus of the research is the quantification the effects of TES for system sizing and boiler cycling. Research is accomplished by modelling TES systems with various storage capacities using thermodynamic analysis. Energy costs are subject to increase during peak usage periods due to a limited supply of energy. Peak heating and cooling periods also force thermal systems to be sized for loads that are only …

Thermal Transport Modeling Of Semiconductor Materials From First Principles, Aliya Qureshi

Masters Theses

Over the past few years, the size of semiconductor devices has been shrinking whereas the density of transistors has exponentially increased. Thus, thermal management has become a serious concern as device performance and reliability is greatly affected by heat. An understanding of thermal transport properties at device level along with predictive modelling can lead us to design of new systems and materials tailored according to the thermal conductivity. In our work we first review different models used to calculate thermal conductivity and examine their accuracy using the experimentally measured thermal conductivity for Si. Our results suggest that empirically calculated rates …

Nano- And Micro-Structured Temperature-Sensitive Hydrogels For Rapidly Responsive Devices, Qi Lu

Doctoral Dissertations

This thesis aims to extend the understanding and explore the application of temperature-responsive hydrogel systems by integrating microelectromechanical systems (MEMS). Stimuli-responsive hydrogel systems are immensely investigated and applied in numerous fields, and interfacing with micro- and nano-fabrication techniques will open up more possibilities. In Chapter 2, the first biologically relevant, in vitro cell stretching device based on hydrogel surface instability was developed. This dynamic platform is constructed by embedding micro-heater devices under temperature-responsive surface-attached hydrogels. The fast and regional temperature change actuates the stretching and relaxation of the seeded human artery smooth muscle cell (HASMC) via controllable surface creasing instability. …

Ultra-Wideband True-Time-Delay Beamforming Networks In A Compact Package, Chris Merola

Doctoral Dissertations

The push for commercial technologies such as 5G Massive MIMO, and consumer broadband internet via low-earth-orbit satellite, drive a need for low cost phased array antenna technologies. A major obstacle in bringing this technology to market is the cost and complexity of the phased array antenna aperture and the required beamforming or multi-beamforming network. This dissertation presents an efficient, reliable, low-cost and mass-manufacturable multi-beamforming network solution. In accomplishing this, a new class of cavity-based, true-time delay multi-beamformer was devised and investigated. Rotman lens optics are implemented for broadband and low phase-error response. The presented topology offers reduction in size and …

Design And Implementation Of Path Finding And Verification In The Internet, Hao Cai

Doctoral Dissertations

In the Internet, network traffic between endpoints typically follows one path that is determined by the control plane. Endpoints have little control over the choice of which path their network traffic takes and little ability to verify if the traffic indeed follows a specific path. With the emergence of software-defined networking (SDN), more control over connections can be exercised, and thus the opportunity for novel solutions exists. However, there remain concerns about the attack surface exposed by fine-grained control, which may allow attackers to inject and redirect traffic. To address these opportunities and concerns, we consider two specific challenges: (1) …

Improving Computer Network Operations Through Automated Interpretation Of State, Abhishek Dwaraki

Doctoral Dissertations

Networked systems today are hyper-scaled entities that provide core functionality for distributed services and applications spanning personal, business, and government use. It is critical to maintain correct operation of these networks to avoid adverse business outcomes. The advent of programmable networks has provided much needed fine-grained network control, enabling providers and operators alike to build some innovative networking architectures and solutions. At the same time, they have given rise to new challenges in network management. These architectures, coupled with a multitude of devices, protocols, virtual overlays on top of physical data-plane etc. make network management a highly challenging task. Existing …

Sequence Control Of Complex Coacervation, Li-Wei Chang

Doctoral Dissertations

Complex coacervation is a liquid-liquid phase separation driven by the complexation of oppositely charged polyelectrolytes. The resulting coacervate phase has been used for many applications, such as underwater adhesives, drug delivery, food and personal care products. There also has been increasing interest in coacervate-like droplets occurring in biological systems. The majority of these “membraneless organelles” involve a combination of intrinsically-disordered proteins and RNA, and phase separate due to long-range charge effects and short-range hydrophobic effects. While evolution has optimized the self-assembly of these types of biological polymers, our ability to design such materials remains limited, in part because the relevant …