Engineering Commons^™

Predicting Water Quality Vulnerability Under Climate Change With Machine Learning, Khanh Thi Nhu Nguyen

Doctoral Dissertations

Water quality deterioration is a global and pervasive issue due to pollution caused by industrialization, urbanization, agriculturalization, and human population growth in the modern era. This issue is even more challenging in the context of climate change due to warming temperatures and the intensification of precipitation. Therefore, assessing the potential impacts of climate change on water quality is a concern. Assessment is necessary so that planners can prepare for and reduce the negative impacts on water quality. At present, climate change impact assessment frameworks are relatively adolescent. Most studies rely on climate projections from General Circulation Models for simulations of …

Experimental Investigation Of Clay Aggregate And Granular Biofilm Behavior, Tao Jiang

Doctoral Dissertations

Clay minerals are a class of phyllosilicates as the major solid constituents in cohesive fine-grained soils (e.g., clays). Owing to their tiny size (i.e., < 2 μm), high aspect ratio, and active surface properties that inherit from the geological process, clay minerals can extensively interact with other suspended matter (e.g., exoployemers, microorganisms) and dissolved ions via the process of flocculation and aggregation, resulting in the formation of larger, porous cohesive particulate aggregates or flocs. Such a complex mechanism of microscale particle interaction generates significant challenges for understanding the bulk clay behavior as a particulate system. In order to better characterize the flocculation and aggregation of clay minerals under various stimuli and to understand the underlying mechanism of particle interactions, particle/aggregate size kinetics of flocculated suspensions of illite, a representative 2:1 clay mineral abundant in marine soils, are studied with varied ionic strength induced by monovalent salt (NaCl), pH, and hydrodynamic shearing in the first phase of this research. Furthermore, a new statistical data binning method termed “bin size index” (BSI) was employed to determine the probability density function (PDF) distributions of flocculated illite suspensions. The statistical results demonstrate that the size kinetics of flocculated illite suspensions is chiefly controlled by the face-to-face and edge-to-face interparticle interactions under the mutual effects of ionic strength and pH, while the hydrodynamic shearing has minimal effects on the variation of particle size groups. In the second phase of this research, the mechanics of clay aggregates are studied using an innovative measurement technique and analytical approach. Individual clay minerals prepared with different mineralogy and salinities are tested via unconfined compression, which shows that the increasing ionic strength can improve the strength and stiffness of clay aggregates, which are further affected by the mineralogical compositions and dominant microfabric in different water chemistry. In the final phase of this research, a collaborative study with an environmental engineer on an NSF CAREER project was conducted to investigate the mechanical behavior of macroscale, light-induced oxygenic granules (biofilm aggregates) using the same technique and analytics developed for the individual clay aggregates. The findings are expected to provide reference values to subsequent studies and engineering practices associated with the water treatment process.

Lateral Response Of Cold-Formed Steel Diaphragms With Variable Sheathing, Hernan Castaneda

Doctoral Dissertations

Cold-formed steel (CFS) framed buildings and subsystems have demonstrated safe and reliable performance while under lateral and seismic loads. Combined with their structural efficiency, this makes CFS-framed buildings popular choice even in high seismic zones. However, due to the complexity in response of CFS members and their interaction in subsystem and system levels, more research needs to be conducted to better understand the overstrength in the system, as well as the contribution of non-structural components to the overall response of the building. The lateral force resisting system (LFRS) of CFS framed buildings consist primarily of shear walls and diaphragms. The …

Optimizing Transportation Systems With Information Provision, Personalized Incentives And Driver Cooperation, Sayeeda Ayaz

Doctoral Dissertations

Poor performance of the transportation systems has many detrimental effects such as higher travel times, increased travel costs, higher energy consumption, and greenhouse gas emissions, etc. This thesis optimizes the transportation systems by addressing the traffic congestion problem and climate change impact resulting from the inefficient operation of these systems. I first focus on the key player of the transportation systems e.g., human being/traveler, and model travelers' route choice behavior with real-time information. In this study, I define looking-ahead behavior in route choice as a traveler's taking into account future diversion possibilities enabled by real-time information in a network with …

Measuring Accessibility To Food Services To Improve Public Health, Efthymia Kostopoulou

Masters Theses

Food accessibility has lately been of primary interest given its impact on public health outcomes. This thesis illustrates the gaps in food access by applying spatial analysis in Massachusetts accounting for a variety of demographic and socioeconomic factors. The number of grocery stores, farmers markets, and convenience stores within 1/4 and 1 mile of the Census tracts’ centroids are the two accessibility metrics used in the spatial analysis. In addition, a regression model is developed using the Gradient Boosting machine learning method to show the relationship between the socioeconomic factors and the number of grocery stores within 1 mile of …

Remote Sensing Of High Latitude Rivers: Approaches, Insights, And Future Ramifications, Merritt E. Harlan

Doctoral Dissertations

High latitude rivers across the pan-Arctic domain are changing due to changes in climate and positive Arctic feedback loops. Understanding and contextualizing these changes is challenging due to a lack of data and methods for estimating and modeling river discharge, and mapping rivers. Remote sensing, and the availability of satellite imagery can provide ways to overcome these challenges. Through combining various forms of fieldwork, modeling, deep learning, and remote sensing, we contribute methodologies and knowledge to three key challenges associated with better understanding high latitude rivers. In the first chapter, we combine field data that can be rapidly deployed with …

Enhancing Management Of Built And Natural Water And Sanitation Systems With Data Science, Nelson Da Luz

Doctoral Dissertations

In the age of the data revolution, the civil engineer can enhance the management of infrastructure systems using new techniques focused on data. This dissertation present three studies in which data science approaches are used to enhance management of water and sanitation systems in both the built and natural environments. Chapters 1 and 2 focus on improving methods for data collection relating to water quality monitoring. In Chapter 1, the efficacy of different water quality sampling program designs is evaluated as the programs relate to meeting monitoring goals. Considerations include how timing, location, and distribution system operations can affect monitoring …

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 …

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 implemented …

Analysis And Fate Of 2,6-Dichloro-1,4-Benzoquinone In Real And Model Drinking Waters, Aarthi Mohan

Doctoral Dissertations

For many years chlorination has served as a barrier to protect human health from waterborne disease outbreaks. Chlorine is viewed as a near-universal oxidant and disinfectant, that provides a stable residual preventing microbial re-growth all the way through the consumer’s tap. Upon reaction with natural organic matter (NOM) however, it forms disinfection by-products (DBPs) many of which are potent human carcinogens and therefore have been of research interest since the 1970’s (Froese et al., 1999; Krasner et al., 2006, 1989; Richardson, 2003; Rook, 1976, 1974; Singer, 1994). The trihalomethanes (THMs) and haloacetic acids (HAAs) are the most prevalent (Krasner et …

Size Progression Of Oxygenic Photogranules (Opgs) And Its Effect On Opg Wastewater Treatment, Ahmed S.A. Abouhend

Doctoral Dissertations

In recent years, the oxygenic photogranule (OPG) process has gained increasing interest because of its potential to treat wastewater without supplemental aeration. Oxygenic photogranules (OPGs) are dense spherical aggregates comprised of phototrophic and nonphototrophic microorganisms. In OPG wastewater treatment reactors, photogranules grow in number as well as in size. The primary goal of this dissertation was to investigate how OPGs grow in size and how the growth affects their structure and functions. We found that OPGs undergo structural changes as they grow bigger in size. As OPGs grow larger, filamentous cyanobacteria become enriched while other phototrophic microbes diminish significantly. OPGs …

Big Data Nanoindentation: Concepts, Principles And Applications To Cemented Materials, Yucheng Li

Doctoral Dissertations

The exploration of oil/gas in the petroleum industry presents a lot of issues both during and after the drilling process, such as wellbore stability, formation clogging, and cementation. Understanding the chemo-mechanical alterations caused by drilling activities to the surrounding formations has been a crucial part of a successful drilling operation. However, as multi-phases, multi-scales, heterogeneous composites, the mechanical properties of rock can vary significantly with its diverse constituent minerals (e.g., quartz, feldspar, and clay minerals) and sometimes hard to be characterized due to the availability of rock samples (i.e., cylindrical core samples are arduous to acquired especially at deep formations). …

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 humic …

Weatherization And Energy Security: A Review Of Recent Events In Ercot, Golbon Zakeri, Maria Hmaria Hernandez, Matthew Lackner, James Manwell

Publications

Purpose of Review

This review addresses the question of energy security. With the transition of energy generation fleet to cleaner, more sustainable electricity production, energy security is a topic of increasing importance.

Recent Findings

Recent events in Texas brought the concept of energy security to the fore. In this review, we examine the makeup of electricity generation and the causes of the February 2021 blackout of Texas. We will investigate the cost/benefit of winterization in Texas and ask why this was not undertaken subsequent to a similar event in 2011.

Summary

We investigate the case of Texas blackout of February …

Influence Of Foundation Damping On Offshore Wind Turbine Monopile Design Loads, Wystan Carswell, Sanjay R. Arwade, Jörgen Johansson, Don J. Degroot

Publications

The dynamic behavior of offshore wind turbines (OWTs) must be designed considering stochastic load amplitudes and frequencies from waves and mechanical loads associated with the spinning rotor during power production. The proximity of the OWT natural frequency to excitation frequencies combined with low damping necessitates a thorough analysis of sources of damping; of these sources of damping, least is known about the contributions of damping from soil-structure interaction (foundation damping). This paper studies the influence of foundation damping on cyclic load demand for monopile-supported OWTs considering the design situations of power production, emergency shutdown, and parked conditions. The NREL 5 …

A Moment In The Sun: Solar Nowcasting From Multispectral Satellite Data Using Self-Supervised Learning, Akansha Singh Bansal, Trapit Bansal, David Irwin

Publications

ABSTRACT

Solar energy is now the cheapest form of electricity in history. Unfortunately,

signi.cantly increasing the electric grid’s fraction of

solar energy remains challenging due to its variability, which makes

balancing electricity’s supply and demand more di.cult. While

thermal generators’ ramp rate—the maximum rate at which they

can change their energy generation—is .nite, solar energy’s ramp

rate is essentially in.nite. Thus, accurate near-term solar forecasting,

or nowcasting, is important to provide advance warnings to

adjust thermal generator output in response to variations in solar

generation to ensure a balanced supply and demand. To address the

problem, this paper develops a …

The Sustainability Of Decarbonizing The Grid: A Multi-Model Decision Analysis Applied To Mexico, Rodrigo Mercado Fernandez, Erin Baker

Publications

Mexico recognizes its vulnerability to the effects of climate change, including sea level rise, increasing average temperatures, more frequent extreme weather events and changes to the hydrological cycle. Because of these concerns Mexico has a vested interest in developing sustainable strategies for mitigating climate change as it develops its electricity grid. In this study, we use a set of sustainability criteria to evaluate a number of model-derived pathways for the electricity grid aimed at meeting Mexico's climate goals. We use a multi-step approach, combining pathways from multiple large scale global models with a detailed electricity model to leverage geographic information …