Theses and Dissertations from UMD
Permanent URI for this communityhttp://hdl.handle.net/1903/2
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item Scalable Rapid Fabrication of Low-Cost, High-Performance, Sustainable Thermal Insulation Foam for Building Energy Efficiency(2024) Siciliano, Amanda Pia; Hu, Liangbing; Material Science and Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bio-based thermal insulation materials offer a promising path towards energy savings in the buildings sector. However, these materials face competitiveness challenges against conventional petroleum-based alternatives due to issues with inferior insulation performance, poor compressive strength, and limited manufacturing scalability. Various fabrication methods such as freeze drying, thermal bonding, and chemical treatment have been proposed to enhance the material’s internal structure by introducing additional pores, creating a more complex path for heat transfer, and improving insulation efficiency. Despite advancements, the manufacturing scalability of these methods and their integration into industrial production remain unachieved.This thesis aims to bridge the gap between laboratory experiments and large-scale production by developing low-cost, sustainable cellulose-based thermal insulation. By investigating both aqueous and non-aqueous-based processing strategies, this work proposes several different fabrication techniques, leading to significant savings in energy, time, and cost. Establishing a comprehensive understanding of the interactions among the fabrication process, insulation foam, manufacturing scalability, and intended product application is imperative. This understanding accounts for variations in processing parameters (e.g., pretreatments, binders, temperature, time) and their impact on the insulation foam’s internal structure and overall performance. By examining the relationship between processing parameters and material structure, this thesis not only advances the fundamental understanding necessary for optimizing fabrication but also provides strategic guidance for selecting and designing scalable bio-based thermal insulation foams. Studying and characterizing commercially viable methods that seamlessly integrate with current industrial infrastructures is crucial for facilitating the transition from small-scale laboratory experimentation to large-scale industrial production. Through various technical strategies, this work illustrates how our understanding can be utilized to offer direction for fabrication method selection, design, and processing, ultimately optimizing the scalable rapid fabrication of low-cost, high-performance sustainable thermal insulation materials for building energy efficiency.Item Understanding Sustainability Practices and Challenges in Making and Prototyping(2024) Dhaygude, Mrunal Sanjay; Peng, Huaishu; Information Studies; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Democratization of prototyping technologies like 3D printers and laser cutters has led to more rapid prototyping practices for the reasons of research, product development and individual interests. While prototyping is becoming a much easier and faster process, there are many sustainability implications neglected. To investigate the current sustainability landscape within the realm of making, we conducted a comprehensive semi-structured interview study involving 15 participants, encompassing researchers, makerspace managers, entrepreneurs, and casual makers. In this paper, we present the findings from this study, shedding light on the challenges, knowledge gaps, motivations, and opportunities that influence sustainable making practices. We discuss potential future paradigms of HCI research to help resolve sustainability challenges in the maker community.Item Urban Sprawl & Critter Crawl: Imagining a More-Than-Human Way of Living(2024) Islam, Ramisa Maisha; Williams, Brittany; Architecture; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Over half of the world’s population lives in urban areas and that number is projected to double by 2050. Cities and urban transects have an important role in addressing climate change. As urban population and development grows, we also see a decline in biodiversity. Humans are not the only species being displaced. Native species lose their natural habitats due to development and seek refuge in urban areas. The complexity of cities allows for urban biodiversity to find a home, but these urban habitats are still human centered, forcing species to fit within a human designed environment. This thesis explores the balance between human living and urban biodiversity to integrate into our cities. Implementing urban biodiversity strategies and more than human design in urban neighborhoods can help to restore biodiversity and strengthen human relationships with the natural environment. Combining these concepts can reimagine the city as a shared ecosystem that serves all species. An ideal shared ecosystem can support urban living, embrace coexistence, and foster a symbiotic relationship between humans and nature.Item BREAKWATER – Breaking the Cycle(2024) Mora, Adrian Bernard Teneza; Gabrielli, Julie; Architecture; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)How can ecological design principles prevent the erosion of the physical and social framework of low-income coastal communities? A significant portion of the world’s population is concentrated along coastlines. Direct access to the water provides access to a longstanding source of economic prosperity and a psychological connection to natural environments. However, human-influenced climate change has produced hazardous environmental conditions that threaten coastal populations, including many poor, vulnerable communities. Disparities in investment for public services, maintenance, and upkeep increases the vulnerability of these disenfranchised groups that cannot protect themselves. The built and natural environment within this diverse boundary zone between the land and sea must be redeveloped as a self-resilient ecosystem that can protect its inhabitants from climate-induced hazards. This renewal will require holistic approaches that can mitigate contemporary impacts to protect current populations at risk and adapt the built environment to better respond in the future.Item The Role of Urban Agriculture in Baltimore Food Systems(2024) Mathews, Meghna Anjali; Zhang, Xin; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The United States is one of the most agriculturally productive countries; and yet, food insecurityremains a significant issue. Urban agriculture in Baltimore, Maryland should be studied further because of its potential to address food insecurity while overcoming systemic barriers created and embedded within food systems. While numerous previous studies have explored food insecurity, knowledge gaps still exist regarding how urban agriculture has influenced food accessibility, and how availability, cultural values of foods, etc. can be improved through increased production and distribution practices of fresher fruits and vegetables in Healthy Food Priority Areas. To address these knowledge gaps, we queried food insecure community members and urban farmers in Baltimore, Maryland to better understand the underlying factors that influence low fruit and vegetable consumption and how they can be mitigated through the establishment of urban agriculture. Urban farmers were interviewed in detail about their production and distribution patterns, and factors influencing the low consumption of fresh fruits and vegetables by community members in Baltimore. Food insecure individuals were asked about their food consumption habits and the accessibility of fruit and vegetables, their food purchasing behavior and related challenges, and community needs. Results indicate that while accessibility and availability are two main factors in fresh produce consumption, there are other important factors that might have received limited attention in existing literature. Our interviews revealed that income, cultural value, and a lack of knowledge in food preparation are key factors in low consumption and purchase of fresh fruits and vegetables. To address the underlying factors and improve the accessibility and availability of fresh produce to low-income communities, it is important to assess community needs and provide policy recommendations that can potentially enhance their nutrition. Ensuring access to individuals with limited resources is a critical component of advancing social justice.Item The Spillover Effect of Environmental Disclosures: Evidence from Customers' Net-zero Pledges(2024) Castillo, Juan; Hann, Rebecca; Business and Management: Accounting & Information Assurance; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This paper investigates the real impact of customers’ voluntary environmental disclosures, specifically, Net-Zero Pledges (NZPs), on the direct greenhouse gas emissions of their suppliers. NZPs represent a growing trend in corporate disclosure, where companies commit to reducing carbon emissions to a minimum level by a specified date, with any remaining emissions being offset by carbon removal actions. Using firms’ connections along the supply chain and a staggered difference-in-differences design, this study provides evidence that suppliers significantly reduce their direct emissions following customers’ NZPs. This effect is more pronounced for NZPs made by customers with greater bargaining power, while suppliers’ reactions are stronger when they have higher carbon intensity and better environmental performance. Furthermore, NZPs of higher quality elicit a stronger response, especially when they limit the use of carbon offsets, set interim targets, and establish public reporting mechanisms. The evidence suggests that this reduction in emissions is achieved by suppliers’ investments in green technologies and innovation, as well as improvements in environmental policies in the years following customers’ NZPs. While these modifications do not seem to change firms’ profitability, they are associated with increased business output and capital investments, though at the expense of additional debt. These findings suggest that customers’ voluntary environmental disclosures can trigger positive spillover effects in upstream suppliers’ real operations, even in the absence of mandatory regulations.Item THE ROLES AND IMPLICATIONS OF AGRICULTURAL AND ENERGY RESOURCES TRADE IN A CLIMATE CHANGE-MITIGATING WORLD(2024) Yarlagadda, Brinda; Hultman, Nathan E.; Public Policy; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Global dependence on agricultural and energy resources trade has grown significantly in the past several decades. In the coming decades, the roles and implications of international trade of various commodities will change, influenced by and important for achieving climate mitigation goals. As globalization increases, new energy technologies emerge, and new climate-oriented trade policies are enacted, there is a need to understand the resulting implications (opportunities and vulnerabilities) on exporters and importers. I present three essays that use the Global Change Analysis Model (GCAM) to evaluate future, inter-regional trade dynamics in a climate-mitigating world. Essay 1 focuses on Latin America and the Caribbean (LAC), a key agricultural exporting region. I show that agricultural market integration (i.e., the reduction of trade barriers) and climate mitigation policies could increase agricultural production and trade opportunities for many LAC economies (particularly in southern South America). Total net export revenue across LAC could reach $110-$270 billion annually by 2050. However, these opportunities could also pose significant economic and environmental trade-offs, including emissions reduction challenges, potential loss of livestock production, increased consumer expenditures, and deforestation and water scarcity pressures. Essay 2 explores the role of liquefied natural gas (LNG) trade as a rapidly emerging technology compared to pipeline natural gas. I analyze how advances in LNG technology, limitations on trade, and climate mitigation policies could affect global and regional vulnerabilities in energy supply. Globally, new additions in LNG and pipeline export infrastructure, range from 330-1330 and 130-440 million tons per annum (MTPA), respectively, by 2050 across scenarios, with the lower end of this range achieved through a transition to a net-zero energy system and limited trade. The results also highlight diverging risks for different gas exporters. For example, Russia, which produces gas largely for pipeline exports, may face larger underutilization due to advances in LNG technology and geopolitical shifts than regions oriented towards domestic and LNG markets, such as the USA and Middle East. Essay 3 evaluates whether import-restrictions on deforestation linked oil crops (i.e., oil palm and soybean) can be effective in reducing deforestation and land use change (LUC) emissions as well as their broader economic implications. I find that current EU restrictions will likely have minimal impact. If extended beyond the EU, import restrictions could drive reductions in cumulative LUC emissions in key oil-crop exporting regions— up to 0.9% in Indonesia, 1.5% in the rest of Southeast Asia, 3.8% in Argentina and 6.7% in Brazil, relative to a scenario with no import restrictions. However, these key exporters could also face losses ranging $4.1-$61 billion in cumulative agricultural production revenue by 2050.Item Ensemble Kalman Inverse Parameter Estimation for Human and Nature Dynamics Two(2023) Karpovich, Maia; Kalnay, Eugenia; Mote, Safa; Applied Mathematics and Scientific Computation; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Since the widespread development of agriculture 10,000 years ago and particularly since the Industrial Revolution beginning in the 18th century, the coupled Earth and Human systems have experienced transformative change. The world's population and Gross Domestic Product have each increased by factors of at least eight in the last two centuries, powered by the intensive use of fossil energy and fossil water. This has had dramatic repercussions on the Earth system's stability, threatened by Human system activities such as habitat destruction, global warming, and depletion of Regenerating and Nonrenewable energy resources that increasingly alter environmental feedbacks. To analyze these changes, we have developed the second generation of the Human and Nature Dynamics model, HANDY2. HANDY2 is designed to simulate the dynamics of energy resources and population over the Industrial era from 1700 to 2200, flexibly incorporating real-world observations of population and energy consumption in an expanded suite of mechanisms that track capital investment, labor force allocation, class mobility, and extraction and production technologies. The use of automated Ensemble Kalman Inversion (EnKI) estimation for HANDY2's parameters allows us to accurately capture the rapid 20th-century rise in the use of phytomass and fossil fuels, as well as the global enrichment of Elites that puts pressure on natural resources and Commoners. EnKI-derived HANDY2 ensembles project that current world policies may lead to a collapse in the world's population by 2200 caused by rapid depletion of resources. However, this collapse can be prevented by a combination of actions taken to support voluntary family planning, lower economic inequality, and most importantly, invest in the rapid expansion of Renewable energy extraction.Item MECHANICS AND THERMAL TRANSPORT MODELING IN NANOCELLULOSE AND CELLULOSE-BASED MATERIALS(2023) RAY, UPAMANYU; Li, Teng; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Cellulose, the abundantly available natural biopolymer, has the potential to be a next generation wonder material. The motivation behind this thesis stems from the efforts to obtain mechanical properties of two novel cellulose-based materials, which were fabricated using top-down (densified engineered wood) and bottoms-up (graphite-cellulose composite) approaches. It was observed that the mechanical properties of both the engineered wood (strength~596 MPa; toughness ~3.9 MJ/m3) and cellulose-graphite composite (strength~715 MPa; toughness ~27.7 MJ/m3) surpassed the equivalent features of other conventional structural materials (e.g., stainless steel, Al alloys etc.). However, these appealing properties are still considerably inferior to individual cellulose fibrils whose diameters are in the order of nanometers. A significant research effort needs to be initiated to effectively transfer the mechanical properties of the hierarchical cellulose fibers from the atomistic level to the continuum. To achieve that, a detailed understanding of the interplay of cellulose molecular chains that affects the properties of the bulk cellulosic material, is needed. Modeling investigations can shed light on such underlying mechanisms that ultimately dictate multiple properties (e.g., mechanics, thermal transport) of these cellulosic materials. To that end, this thesis (1) applies molecular dynamics simulations to decipher why microfibers made of aligned nanocellulose and carbon nanotubes possess excellent mechanical strength, along with understanding the role of water in fully recovering elastic wood under compression; (2) delineates an atomistically informed multi-scale, scalable, coarse grained (CG) modeling scheme to study the effect of cellulose fibers under different representative loads (shearing and opening), and to demonstrate a qualitative guideline for cellulose nanopaper design by understanding its failure mechanism; (3) utilizes the developed multi-scale CG scheme to illustrate the reason why a hybrid biodegradable straw, experimentally fabricated using both nano- and micro-fibers, exhibits higher mechanical strength than individual straws that were built using only nano or microfibers; (4) investigates the individual role of nanocellulose and boron nitride nanotubes in increasing the mechanical properties (tensile strength, stiffness) of the derived nanocellulose/boron-nitride nanotube hybrid material; (5) employs reverse molecular dynamics approach to explore how the boron nitride nanotube based fillers can improve thermal conductivity (k) of a nanocellulose derived material. In addition, this thesis also intends to educate the readers on two perspectives. The common link connecting them is the method of engineering intermolecular bonds. The first discussion presents a few novel mechanical design strategies to fabricate high-performance, cellulose-based functional materials. All these strategies are categorized under a few broad themes (interface engineering, topology engineering, structural engineering etc.). Another discussion has been included by branching out to other materials that, like nanocellulose, can also be tuned by intermolecular bonds engineering to achieve unique applications. Avenues for future work have been suggested which, hopefully, can act as a knowledge base for future researchers and help them formulate their own research ideas. This thesis extends the fundamental knowledge of nanocellulose-based polymer sciences and aims to facilitate the design of sustainable and programmable nanomaterials.Item Symbiosis: Recalibrating Design Thinking for the Urban Environment(2023) Ripley, Benjamin Allan; Tilghman, James W; Architecture; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Architecture is stiff, rigid, and tough to change, but in an ever-changing world, our built environment needs to be able to respond in kind. Without planning and designing for adaptability, the built environment lags behind the numerous societal and environmental dynamics that challenge our present time. Impending issues of climate change and rapid urbanization are now forcing architecture to reexamine itself and ask, how will it respond to these complex demands? In the face of this challenge, this thesis will explore a conceptually different approach to the design process that demands an inherently different product. Through an emphasis on systems thinking and development, architecture can be designed to exist within a symbiotic relationship with the natural environment, where our buildings could react and interact with the shifting nature of our culture and natural environments over time. Thus, through this strategy inspired by organic organisms, the architecture is then able to better embrace the context over time and become a truly sustainable model for urban development.