Engineering Commons^™

Euplectella Aspergillum’S Natural Lattice Structure For Structural Design & Stability Landscape Of Thin Cylindrical Shells With Dimple Imperfections, Zoe Y. Sloane

Masters Theses

The first portion of this thesis assesses the structural application of a bracing design inspired by the deep-sea sponge, Euplectella Aspergillum. Many studies have investigated the natural strength found in the unique skeletal structure of this species. The braced design inspired by the sponge features square frames with two sets of cross-braces that are offset from the corners of each frame, creating a pattern of open and closed cells. This study reports the results of multiple Finite Element Analysis (FEA) computations that compare the described bracing pattern to a more common bracing design used in structural design. The designs are ...

Application Of The New Iec International Design Standard For Offshore Wind Turbines To A Reference Site In The Massachusetts Offshore Wind Energy Area, Samuel C. Roach

Masters Theses

This thesis summarizes the simulation and analysis performed for the MassCEC project described herein. The intent was to perform a “dry run” of the new IEC offshore wind turbine design standard, IEC 61400-3-1 and to illustrate the use of that standard in the Massachusetts Offshore Wind Energy Area. IEC 61400-3-1 is a design standard used to ensure wind turbine structural performance over the design life of the machine. Each installed wind turbine must be certified by a Certified Verification Agent using this standard before installation. The certification process typically uses a structural dynamics model to predict a turbine’s structural ...

Equitable Resource Allocation To Improve Safety: An Evaluation Based On Risk, Alyssa M. Ryan

Doctoral Dissertations

Transportation safety continues to be a serious issue throughout the world. Proven safety measures have been developed to increase the safety on all roadways, but have not been universally and equitably implemented due to lack of resources, inefficiencies, and understanding. Additionally, the relative level of mobility safety remains higher in certain environments than others, creating an inequitable landscape. In this dissertation, the efficiency of using local and statement resources to improve safety is investigated while controlling for level of safety risk in vulnerable environments and locations using a comprehensive approach. Several methodologies and techniques are employed and developed to examine ...

The Role Of Extracellular Polymeric Substances In The Accumulation And Transport Of Polystyrene Nanoparticles In Biofilms, Joann Marie Rodríguez Suarez

Doctoral Dissertations

With the increasing number of nanotechnology applications, it is reasonable to expect nanoparticles to be ubiquitous in biofilms found in natural and engineered aquatic systems. We studied the impact of the degree of cross-linking on the deposition and diffusion of polystyrene nanoparticles (NPs) in alginate model biofilm matrices in the presence and absence of calcium cross-linkers using image correlation methods and single particle tracking. We found that cross-linking increases the viscoelasticity and hydration of the polymeric matrix and leads to structural changes that can restrict and alter the diffusive behavior of NPs, but the magnitude of the effects on diffusion ...

Assessing The Impact Of Bicycle Treatments On Bicycle Safety: A Multi-Methods Approach, Aikaterini Deliali

Doctoral Dissertations

Compared to other modes, bicyclists are disproportionally affected by crashes considering their low mode share. There is evidence that crashes between bicyclists and motorized vehicle take place at road segments and signalized intersections where bicycle treatments (e.g., bike lanes) are present, urging for in-dept analysis of the safety impact of the various bicycle treatment types. Additionally, it is important to identify sensor types that have the potential to advance field data collection and traffic monitoring in multi-modal road environments. In this dissertation, three approaches, namely crash analysis, traffic conflict analysis, and analysis of driver speeding and glancing behavior, were ...

Distributed Learning Algorithms: Communication Efficiency And Error Resilience, Raj Kumar Maity

Doctoral Dissertations

In modern day machine learning applications such as self-driving cars, recommender systems, robotics, genetics etc., the size of the training data has grown to the point that it has become essential to design distributed learning algorithms. A general framework for the distributed learning is \emph{data parallelism} where the data is distributed among the \emph{worker machines} for parallel processing and computation to speed up learning. With billions of devices such as cellphones, computers etc., the data is inherently distributed and stored locally in the users' devices. Learning in this set up is popularly known as \emph{Federated Learning}. The ...

Characterizing Mechanical Regulation Of Bone Metastatic Breast Cancer Cells, Boyuan Liu

Doctoral Dissertations

Breast cancer most frequently metastasizes to the skeleton. Bone metastatic cancer is incurable and induces wide-spread bone osteolysis, resulting in significant patient morbidity and mortality. Mechanical stimuli in the skeleton are an important microenvironmental parameter that modulates tumor formation, osteolysis, and tumor cell-bone cell signaling, but which mechanical signals are the most beneficial and the corresponding molecular mechanisms are unknown. This work focused on bone matrix deformation and interstitial fluid flow based on their well-known roles in bone remodeling and in primary breast cancer. The goal of our research was to establish a platform that could define the relationship between ...

Modeling Chain Packing In Complex Phases Of Self-Assembled Block Copolymers, Anugu Abhiram Reddy

Doctoral Dissertations

Block copolymer (BCP) melts undergo microphase seperation and form ordered soft matter crystals with varying domain shapes and symmetries. We study the con- nection between diblock copolymer molecular designs and thermodynamic selection of ordered crystals by modeling features of variable sub-domain geometry filled with individual blocks within non-canonical sphere-like and network phases that together with layered, cylindrical and canonical spherical phases forms “natural forms” of self- assembled amphiphilic soft matter at large. First, we present a model to revise our understanding of optimal Frank-Kasper sphere-like morphologies by advancing the- ory to account for varying domain volumes. We then develop generic ...

New Isomeric Silicones: Synthesis, Compositions And Surface Properties, Yan Cong

Doctoral Dissertations

This dissertation presents research performed in the field of silicone polymer science, which refers to polymers with alternating silicon-oxygen backbones. Three research topics will be explored. The first topic involves the synthesis of trimethylsiloxysilsesquioxane (MT) copolymers with vinyl and hydride functionalities as reactive liquid silicone precursors. The second topic describes titration of dimethylsiloxy (D) composition into trimethylsiloxysilsesquioxane (MT) copolymers for the purpose of controlling the mechanical properties and thermal stabilities of the material. The last topic explores the modification of hydrophobic silicone surfaces with oxygen plasma to form silica-like, hydrophilic surfaces and the behaviors of hydrophobic recovery.

The first chapter ...

Moving Polygon Methods For Incompressible Fluid Dynamics, Chris Chartrand

Doctoral Dissertations

Hybrid particle-mesh numerical approaches are proposed to solve incompressible fluid flows. The methods discussed in this work consist of a collection of particles each wrapped in their own polygon mesh cell, which then move through the domain as the flow evolves. Variables such as pressure, velocity, mass, and momentum are located either on the mesh or on the particles themselves, depending on the specific algorithm described, and each will be shown to have its own advantages and disadvantages. This work explores what is required to obtain local conservation of mass, momentum, and convergence for the velocity and pressure in a ...

Decision-Analytic Models Using Reinforcement Learning To Inform Dynamic Sequential Decisions In Public Policy, Seyedeh Nazanin Khatami

Doctoral Dissertations

We developed decision-analytic models specifically suited for long-term sequential decision-making in the context of large-scale dynamic stochastic systems, focusing on public policy investment decisions. We found that while machine learning and artificial intelligence algorithms provide the most suitable frameworks for such analyses, multiple challenges arise in its successful adaptation. We address three specific challenges in two public sectors, public health and climate policy, through the following three essays.

In Essay I, we developed a reinforcement learning (RL) model to identify optimal sequence of testing and retention-in-care interventions to inform the national strategic plan “Ending the HIV Epidemic in the US ...

Computational Study Of Internal Flow, Near Nozzle And External Spray Of A Gdi Injector Under Flash-Boiling Conditions, Chinmoy Krushna Mohapatra

Doctoral Dissertations

The early and late portions of transient fuel injection have proven to be a rich area
of research, especially since the end of injection can cause a disproportionate amount
of emissions in direct injection internal combustion engines. While simulating the
internal flow of fuel injectors, valve opening and closing events are the perennial
challenges. A typical adaptive-mesh CFD simulation is extremely computationally
expensive, as the small gap between the needle valve and the seat requires very
small cells to be resolved properly. Capturing complete closure usually involves a
topological change in the computational domain. Furthermore, Internal Combustion
Engines(ICE) operating ...

Computational Rational Design Of Electrocatalysts For Electrochemical Ammonia And Hydrogen Synthesis, Akash Jain

Doctoral Dissertations

The electrochemical hydrogen evolution reaction (HER) and nitrogen reduction reaction (NRR) offer fossil-fuel-free routes for hydrogen and ammonia synthesis, respectively. However, currently, both processes lack suitable electrocatalysts for practical applications. Thus, this dissertation focuses on the computational rational design of HER and NRR electrocatalysts.

HER is most efficiently catalyzed by platinum (Pt), which is expensive. To reduce the catalyst cost, we investigate core-shell nanoparticles of inexpensive tungsten-carbide (WC) and Pt (WC@Pt). Using first-principles density functional theory (DFT) calculations, we compare the suitability of two WC phases, α-WC and β-WC as support materials for Pt overlayers. We dope WC with ...

Data-Driven Control, Modeling, And Forecasting For Residential Solar Power, Akansha Singh Bansal

Doctoral Dissertations

Distributed solar generation is rising rapidly due to a continuing decline in the cost of solar modules. Most residential solar deployments today are grid-tied, enabling them to draw power from the grid when their local demand exceeds solar generation and feed power into the grid when their local solar generation exceeds demand. The electric grid was not designed to support such decentralized and intermittent energy generation by millions of individual users. This dramatic increase in solar power is placing increasing stress on the grid, which must continue to balance its supply and demand despite the potential for large solar fluctuations ...

Improving Young Driver Perceptions Of Vulnerable Road Users Through A Persuasive Intervention, Shashank Mehrotra

Doctoral Dissertations

Vulnerable road users (VRUs), including bicyclists, pedestrians, and road users of other modalities, are at a higher risk of collision with young drivers when a complex traffic situation presents itself. Past research has established the importance of young drivers’ perceptions about VRUs that would encourage safe behavior. This research designed and evaluated a novel persuasive intervention that can help improve the perceptions of young drivers while they interact with VRUs. The study identified young drivers’ perceptions towards VRUs who have been licensed in the past 12 to 18 months through structured interviews. Based on these findings, an interactive intervention was ...

Silicon Germanium Bicmos Integrated Circuits For Scalable Cryogenic Sensing Applications, Mohsen Hosseini

Doctoral Dissertations

This dissertation is focused on an investigation of BiCMOS cryogenic low noise amplifiers (LNAs) based on Silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) for simultaneous low noise and low power design and also taking advantage of CMOS circuitry for adding flexibility to the LNA design. Cryogenic LNAs' scalability challenges are discussed and addressed in the dissertation. To achieve that, first, HBTs of three state-of-the-art technologies are characterized and modeled at cryogenic temperature. It is shown that SiGe HBT provides a promising compromise of noise temperature, power consumption, and bandwidth. Moreover, a scalable on-chip approach is proposed and verified for biasing of ...

Controlled Codelivery Of Mir-26a And Antagomir-133a With Osteoconductive Scaffolds To Promote Healing Of Large Bone Defects, Cole J. Ferreira

Masters Theses

Often caused by trauma or tumor removal, large bone defects frequently result in delayed or non-union. The current gold standard for treatment is autograft. However, due to limitations, such as the size and location of the defect, these cannot always be utilized. A common alternative to autograft is the use of BMP-2 with a collagen scaffold, however, this treatment is limited by numerous side effects. In recent years, genetic materials such as microRNAs (miRNAs) have offered possible alternative therapies. MiRNAs are small non-coding RNA molecules that generally range from 20-24 nucleotides, serve as repressors of gene expression, and are involved ...

Modeling Power Generation Losses Due To Environmental And Fish Passage Attraction Flows At A Run-Of-River Hydroelectric Operation In The Northeast, Elizabeth A. Lotter

Environmental & Water Resources Engineering Masters Projects

Environmental mitigation represents an important, recurring cost to the hydropower industry, the largest renewable power source in the United States. Environmental flows are one such expense whereby hydro operations maintain a minimum flow in the river to mitigate impacts on aquatic and riparian ecosystems. Any hydroelectric facility may have a habitat maintenance flow requirement, but facilities with assisted aquatic organism passage structures, or fishways, may be subject to additional flow requirements associated with specific species migrations. This study assesses the economic impact of meeting environmental flow requirements in terms of losses to power generation at a representative hydroelectric facility and ...

Natural Organic Matter (Nom) Precursors Characterization In Source Water By Surrogate Measurements And Disinfection Byproducts (Dbps) Analysis, Mohammad (Kiron) Shakhawat

Environmental & Water Resources Engineering Masters Projects

Natural organic matter (NOM) is the main source of organic precursors for organic disinfection byproducts (DBPs) in treated drinking water.Aquatic NOM is a heterogeneous mixture consisting of both hydrophobic and hydrophilic compounds. The hydrophobic fraction includes humic substances, primarily humic acids and fulvic acids. In most waters, fulvic acid is considered to be the major portion of the hydrophobic fraction. Humic substances are formed by decaying vegetative matter, such as lignin. Lignin is found in plants and is quite resistant to biodegradation, yet it is reactive with oxidants, such as chlorine. Thus, water continuing higher amounts of aromatic hydrophobic ...

Anaerobic Digestion: Awareness, Implementation, And Simulation, Kieran Tay, Nicholas Sbalbi, Michael Forozis, Flo Sabatini

Student Showcase

Anaerobic digestion (AD) is the process in which organic matter is fermented in an oxygen-deprived environment to produce renewable biogas. Our project is multi-faceted, with the overall goal of raising public awareness of AD as a transitional energy source. To that end, our group has named itself Undergraduates Raising Awareness for Anaerobic Digestion (URAAD). We are approaching this goal on three fronts, including (i) a website, (ii) a physical lab-scale digester, and (iii) a computer simulation of anaerobic digestion.

The first component, the website, was developed with the aim of serving as a resource for the public. It includes educational ...

Spring 2022 Superhydrophobic Materials, T. Leo Liu

Science and Engineering Saturday Seminars

Many natural surfaces, such as lotus leaves and a water strider’s leg, have shown striking water repellency so that they remain clean and dry even in “dirty” habitats. Such water repellency is called superhydrophobicity, which has stimulated lots of science and engineering imagination for self-cleaning windows, never dirty clothes, drag-reduction swimming suits, etc. In this workshop, we will use superhydrophobicity as a model to guide an integrative teaching and learning experience through hands-on experiments, critical thinking, basic science, as well as a lecture on state-of-the-art research discoveries. The objectives of this workshop are to (1) stimulate student curiosity and ...

Design And Testing Of A Foundation Raised Oscillating Surge Wave Energy Converter, Jacob R. Davis

Masters Theses

Our oceans contain tremendous resource potential in the form of mechanical energy. With the ability to capture and convert the energy carried in surface waves into usable electricity, wave energy converters (WECs) have been a long-held aspiration in ocean renewable energy. One of the most popular wave energy design concepts is the Oscillating Surge Wave Energy Converter (OSWEC). True to their namesake, OSWECs extract energy from the surge force induced by incident waves. In their most basic form, OSWECs are analogous to a bottom-hinged paddle which pitches fore and aft in the direction of wave motion. Most commonly, OSWECs are ...

Robustness Of Supply Chain Synchronization Strategies, Andrew Frere

Masters Theses

Modern manufacturing systems dealing with complex assemblies with large numbers of parts present particular challenges in the realm of supply chain management. Complex assemblies, such as those found in aerospace and automobile manufacturing, require thousands of parts to come together at the right time for final assembly. The large number of parts, often coming from hundreds of suppliers, combined with unreliable delivery times and high cost of many of these components can lead to incredibly high inventory costs and assembly delays. Typically, variable delays in part delivery are compensated for by either keeping a buffer of safety stock or a ...

Comparing And Improving The Design Of Physical Activity Data Visualizations, Peter M. Frackleton

Masters Theses

Heart disease is a leading cause of death in the United States, and older adults are at highest risk of being diagnosed with heart disease. Consistent physical exercise is an effective means of deterring onset of heart disease, and physical activity tracking devices can inspire greater activity in older adults. However, physical activity tracking device abandonment is quite common due to limitations on what can be learned from the activity data that is collected. Better data visualization of physical data presents an opportunity to surpass these limitations. In this thesis, a task-based human subject study was performed with three different ...

Modeling And Characterization Of Optical Metasurfaces, Mahsa Torfeh

Masters Theses

Metasurfaces are arrays of subwavelength meta-atoms that shape waves in a compact and planar form factor. During recent years, metasurfaces have gained a lot of attention due to their compact form factor, easy integration with other devices, multi functionality and straightforward fabrication using conventional CMOS techniques. To provide and evaluate an efficient metasurface, an optimized design, high resolution fabrication and accurate measurement is required. Analysis and design of metasurfaces require accurate methods for modeling their interactions with waves. Conventional modeling techniques assume that metasurfaces are locally periodic structures excited by plane waves, restricting their applicability to gradually varying metasurfaces that ...

Action : Adaptive Cache Block Migration In Distributed Cache Architectures, Chandra Sekhar Mummidi

Masters Theses

Increasing number of cores in chip multiprocessors (CMP) result in increasing traffic to last-level cache (LLC). Without commensurate increase in LLC bandwidth, such traffic cannot be sustained resulting in loss of performance. Further, as the number of cores increases, it is necessary to scale up the LLC size; otherwise, the LLC miss rate will rise, resulting in a loss of performance. Unfortunately, for a unified LLC with uniform cache access time, access latency increases with cache size, resulting in performance loss. Previously, researchers have proposed partitioning the cache into multiple smaller caches interconnected by a communication network which increases aggregate ...

Benchmarking Small-Dataset Structure-Activity-Relationship Models For Prediction Of Wnt Signaling Inhibition, Mahtab Kokabi

Masters Theses

Quantitative structure-activity relationship (QSAR) models based on machine learning algorithms are powerful tools to expedite drug discovery processes and therapeutics development. Given the cost in acquiring large-sized training datasets, it is useful to examine if QSAR analysis can reasonably predict drug activity with only a small-sized dataset (size < 100) and benchmark these small-dataset QSAR models in application-specific studies. To this end, here we present a systematic benchmarking study on small-dataset QSAR models built for prediction of effective Wnt signaling inhibitors, which are essential to therapeutics development in prevalent human diseases (e.g., cancer). Specifically, we examined a total of 72 two-dimensional (2D) QSAR models based on 4 best-performing algorithms, 6 commonly used molecular fingerprints, and 3 typical fingerprint lengths. We trained these models using a training dataset (56 compounds), benchmarked their performance on 4 figures-of-merit (FOMs), and examined their prediction accuracy using an external validation dataset (14 compounds). Our data show that the model performance is maximized when: 1) molecular fingerprints are selected to provide sufficient, unique, and not overly detailed representations of the chemical structures of drug compounds; 2) algorithms are selected to reduce the number of false predictions due to class imbalance in the dataset; and 3) models are selected to reach balanced performance on all 4 FOMs. These results may provide general guidelines in developing high-performance small-dataset QSAR models for drug activity prediction.

Internet Infrastructures For Large Scale Emulation With Efficient Hw/Sw Co-Design, Aiden K. Gula

Masters Theses

Connected systems are becoming more ingrained in our daily lives with the advent of cloud computing, the Internet of Things (IoT), and artificial intelligence. As technology progresses, we expect the number of networked systems to rise along with their complexity. As these systems become abstruse, it becomes paramount to understand their interactions and nuances. In particular, Mobile Ad hoc Networks (MANET) and swarm communication systems exhibit added complexity due to a multitude of environmental and physical conditions. Testing these types of systems is challenging and incurs high engineering and deployment costs. In this work, we propose a scalable MANET emulation ...

Metabolic Modeling Of Cystic Fibrosis Airway Microbiota From Patient Samples, Arsh Vyas

Masters Theses

Cystic Fibrosis (CF) is a genetic disorder, found with higher prevalence in the Caucasian population, affecting > 30,000 individuals in the United States and > 70,000 worldwide. Due to the astoundingly high rate of mortality among CF patients being attributed to respiratory failure brought on by chronic bacterial infections and subsequent airway inflammation, there has been a lot of focus on systematically analyzing CF lung airway communities. While it is observed traditionally that Pseudomonas aeruginosa is the most threatening and persistent CF colonizer due to high antibiotic resistance, recent studies have elicited the roles of other pathogens and it has ...

Synthesis Of Functionalized Acrylic Nanoparticles As A Precursor To Bifunctional Colloids, Guinevere E. Tillinghast

Masters Theses

Water-borne coatings have increased in popularity due to the recent environmental regulations being placed on coating formulation. The most readily available coatings without volatile organic compounds are thermoplastic polymer dispersions that rely on interdiffusion to form a film. These dispersions are reliant on toxic crosslinking chemistries to achieve adequate coating mechanical properties, but still have significantly inferior properties when compared with current thermosetting industrial coatings that contain volatile organic compounds. As a result, waterborne coatings made with conventional emulsion polymers cannot be considered for high-performance coatings. Polyurethane dispersions have been developed that can meet these demands, but require several lengthy ...