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Description
Both molecular structure of macromolecular materials and subsequent processing of these materials dictate resulting material properties. In this work novel synthetic strategies combined with detailed analytical methodology reveal fundamental structure-processing-property relationships in thermoplastic polyesters, thermoplastic polyurethanes, covalently crosslinked acetal functionalized networks, and small molecule surfactants. 4,4’ dimethyloxybisbenzoate afforded a series of novel polyester structures, and the incorporation of this monomer both increased the Tg and decreased the crystallinity in cyclohexane dimethanol based polyesters. Solubility and dynamic light scattering experiments combined with oscillatory rheology techniques provided methodology to validate polyurethane extrusion in commercial polyurethanes. Acid catalyzed hydroxyl addition to vinyl ethers provided two families of acetal functionalized poly(ethylene glycol hydrogels). Stoichiometric control of binary thiol-acrylate polymerizations afforded hydrogels with both tunable mechanical properties and predictable degradation profiles. Following this work, a photoacid generator catalyzed cationic catalysis provided acetal functionalized organogels whose mechanical properties were predicted by excess vinyl ether monomers which underwent cationic polymerization under the same reaction conditions that yielded acetal functionalization. Time resolved FT-IR spectroscopy provided new understanding in hydroxyl vinyl ether reactions, where both hydroxyl addition to a vinyl ether and vinyl ether cationic polymerization occur concurrently. This work inspired research into new reactive systems for photobase generator applications. However, current photobase generator technologies proved incompatible for carbon-Michael reactions between acetoacetate and acrylate functionalities as a result of uncontrollable acrylate free radical polymerization. The fundamental knowledge and synthetic strategies afforded by these investigations were applied to small molecule surfactant systems for fire-fighting applications. Triethylsilyl-containing zwitterionic and cationic surfactants displayed surface tensions lower than hydrocarbon surfactants, but larger than siloxane-containing surfactants. For the first time, oscillatory rheology and polarized optical light imagine rheology highlighted shear-induced micelle alignment in triethylsilyl surfactants, which provided more stable foams than zwitterionic analogues. The knowledge gained from these investigations provided fundamental structure-processing-property relationships in small molecule surfactant solutions applied as fire-fighting foams. This discovery regarding the effect of self-assembled structures in foam solutions informs the design and analysis of next generation surfactants to replace fluorocarbon surfactants in fire-fighting foam applications.
ContributorsBrown, James Robert (Author) / Long, Timothy E (Thesis advisor) / Bortner, Michael J (Committee member) / Biegasiewicz, Kyle F (Committee member) / Jin, Kailong (Committee member) / Arizona State University (Publisher)
Created2023
Description
Navigation and mapping in GPS-denied environments, such as coal mines ordilapidated buildings filled with smog or particulate matter, pose a significant challenge
due to the limitations of conventional LiDAR or vision systems. Therefore there
exists a need for a navigation algorithm and mapping strategy which do not use vision
systems but are still able to explore and map the environment. The map can further
be used by first responders and cave explorers to access the environments.
This thesis presents the design of a collision-resilient Unmanned Aerial Vehicle
(UAV), XPLORER that utilizes a novel navigation algorithm for exploration and
simultaneous mapping of the environment. The real-time navigation algorithm uses
the onboard Inertial Measurement Units (IMUs) and arm bending angles for contact
estimation and employs an Explore and Exploit strategy. Additionally, the quadrotor
design is discussed, highlighting its improved stability over the previous design.
The generated map of the environment can be utilized by autonomous vehicles to
navigate the environment. The navigation algorithm is validated in multiple real-time
experiments in different scenarios consisting of concave and convex corners and circular
objects. Furthermore, the developed mapping framework can serve as an auxiliary
input for map generation along with conventional LiDAR or vision-based mapping
algorithms.
Both the navigation and mapping algorithms are designed to be modular, making
them compatible with conventional UAVs also. This research contributes to the
development of navigation and mapping techniques for GPS-denied environments,
enabling safer and more efficient exploration of challenging territories.
ContributorsPandian Saravanakumaran, Aravind Adhith (Author) / Zhang, Wenlong (Thesis advisor) / Das, Jnaneshwar (Committee member) / Berman, Spring (Committee member) / Arizona State University (Publisher)
Created2023
Description
Acrylate polymers are a versatile class of polymers that have found extensive applications in diverse fields, including adhesive, coatings, packaging, cosmetics, textile, food, electronics, and automotive industries. Incorporating crosslinking elements such as supramolecular chemistry or photoreactive group imparts unique and desirable properties to the resulting acrylate polymers. In the first project, regioselective Michael addition allowed the efficient installation of the nucleobase, guanine and cytosine, on acrylate-containing monomers, which enabled the preparation of a series of nucleobase functionalized acrylate and n-butyl acrylate copolymers using conventional free radical copolymerization. Guanine-containing copolymers exhibited superior thermal, thermomechanical, and morphological properties than cytosine-containing copolymer analogs due to the relatively strong guanine self-association. Further understanding of rheological, mechanical, and adhesive properties revealed the influence of guanine content and provided valuable information for designing and optimizing guanine-containing copolymers for elastomers and adhesives. Controlled radical polymerization enabled the synthesis of guanine and cytosine-containing triblock copolymers. Blending these two triblock copolymers formed supramolecular networks through molecular recognitions between guanine and cytosine and enhanced polymer self-assembly. Next, incorporating spiropyran photoisomerization functional groups in the acrylate copolymer enabled the formation of zwitterionic polymers upon ultraviolet (UV) radiation, which facilitated the Cu ion removal from aqueous solutions. The final project aimed to synthesize a family of macro-crosslinkers bearing an acrylate pendant group, which demonstrated compatibility with versatile reactive diluents, such as poly(dimethyl siloxane) and epoxy. The designed macro-crosslinkers showed promise in developing UV adhesives with desirable properties, such as low shrinkage, fast curing, and high thermal stability. These projects offered valuable insights into the fundamental structure-property-morphology relationships in crosslinked acrylic polymers that incorporate supramolecular chemistry or photoreactive functional groups, paving the way for new advances in the design of acrylate polymer with enhanced mechanical and morphological properties.
ContributorsLiu, Boer (Author) / Long, Timothy TEL (Thesis advisor) / Moore, Robert RBM (Committee member) / Jin, Kailong KJ (Committee member) / Biegasiewicz, Kyle KFB (Committee member) / Arizona State University (Publisher)
Created2023
Description
Solar photovoltaic (PV) generation has seen significant growth in 2021, with an increase of around 22% and exceeding 1000 TWh. However, this has also led to reliability and durability issues, particularly potential induced degradation (PID), which can reduce module output by up to 30%. This study uses cell- and module-level analysis to investigate the impact of superstrate, encapsulant, and substrate on PID.The influence of different substrates and encapsulants is studied using one-cell modules, showing that substrates with poor water-blocking properties can worsen PID, and encapsulants with lower volumetric resistance can conduct easily under damp conditions, enabling PID mechanisms (results show maximum degradation of 9%). Applying an anti-soiling coating on the front glass (superstrate) reduces PID by nearly 53%. Typical superstrates have sodium which accelerates the PID process, and therefore, using such coatings can lessen the PID problem.
At the module level, the study examines the influence of weakened interface adhesion strengths in traditional Glass-Backsheet (GB) and emerging Glass-Glass (GG) (primarily bifacial modules) constructions. The findings show nearly 64% more power degradation in GG modules than in GB. Moreover, the current methods for detecting PID use new modules, which can give inaccurate information instead of DH-stressed modules for PID testing, as done in this work.
A comprehensive PID susceptibility analysis for multiple fresh bifacial constructions shows significant degradation from 20 to 50% in various constructions. The presence of glass as the substrate exacerbates the PID problem due to more ionic activity available from the two glass sides. Recovery experiments are also conducted to understand the extent of the PID issue.
Overall, this study identifies, studies, and explains the impact of superstrate, substrate, and encapsulant on the underlying PID mechanisms. Various pre- and post-stress characterization tests, including light and dark current-voltage (I-V) tests, electroluminescence (EL) imaging, infrared (IR) imaging, and UV fluorescence (UVF) imaging, are used to evaluate the findings. This study is significant as it provides insights into the PID issues in solar PV systems, which can help improve their performance and reliability.
ContributorsMahmood, Farrukh ibne (Author) / Tamizhmani, Govindasamy (Thesis advisor) / Rogers, Bradley (Committee member) / Oh, Jaewon (Committee member) / Rajadas, John (Committee member) / Arizona State University (Publisher)
Created2023
Description
After many decades of promoting sustainable tourism and development, the world faces the pressing issue of overtourism. Overtourism is viewed as the condition where the growth of visitor volume puts destinations’ capacity under pressure resulting in many negative impacts on the environment, economy, culture, and society. It causes many community residents to resent tourism development. Visitors are concerned about their travel experience in overcrowded places. Understanding overtourism is necessary for destination management. This dissertation includes three studies to: 1) review the phenomenon of overtourism; 2) examine the perceptions of local residents and test the relationship between their satisfaction with quality of life and level of support for tourism development in overtourism context; and 3) examine the management of stakeholder involvement in an evidence-based sustainable tourism plan that aims to address overtourism. Different research methods are employed in the three studies of the dissertation: a conceptual paper based on literature review; a concurrent triangulation approach using both quantitative and qualitative data collected from a survey with host community; and a case study involving analysis of documents related to a sustainable tourism plan and in-depth interviews with key informants who were involved in developing the plan. Several theoretical or conceptual frameworks are used to guide research, including those that consider the relationship between residents’ satisfaction with QOL and their support for tourism development, crowding theory, stress coping framework, place attachment, and a multi-stakeholder involvement management framework. Sedona, a destination that is concerned about overtourism, was chosen to be the research site for two of the studies. Study 1 reveals the complexity of overtourism and pinpoints important aspects and details (e.g., causes, impacts) that need to be considered while solving overtourism. Study 2 investigates impacts of overtourism on the quality of life of the host community and identifies different ways residents cope with the crowding condition. Residents’ support for tourism development is influenced by their satisfaction with quality of life and possibly by their attachment to destination. Study 3 documents a comprehensive mechanism to manage stakeholder involvement and utilization of evidence in a sustainable tourism plan. Findings are helpful for destination management.
ContributorsPham, Kim (Author) / Andereck, Kathleen (Thesis advisor) / Vogt, Christine (Thesis advisor) / Nyaupane, Gyan (Committee member) / Morgan, Mark (Committee member) / Arizona State University (Publisher)
Created2023
Description
Nature-based recreation is a popular way for people to interact with the environment that also confers numerous economic and health benefits. It is important that the social-ecological systems (SES) that host nature-based recreation be managed effectively, both to preserve the benefits of this important human-environment interaction, and to avoid the potential negative outcomes of recreational commons. The SES that host nature-based recreation are characterized by complex and dynamic feedbacks that complicate their management. Managing these systems is made more complex by the suite of external, multi-scalar, and anthropogenic forces (e.g., climate change, trans-boundary pollution) that plague them with increasing frequency. This dissertation investigates the importance of accounting for this full range of system feedbacks when managing for nature-based recreation. I begin with a broad discussion of the types of dilemmas faced by managers of nature-based recreation. I create a systems-thinking typology of management dilemmas that apply across different recreation modes and system contexts, and which are characterized as feedbacks within the broader recreational system. My findings in this chapter have important implications for understanding and anticipating how different exogenous and endogenous shocks (including management interventions, themselves) may work through or change the processes in SES that host nature-based recreation. In the following two chapters, I narrow my focus to examine case studies of specific dilemma archetypes and proposed management interventions. First, I perform an ex ante analysis of a prospective policy response to a regulatory spiral of excess recreational fishing effort and abridged fishing seasons in the U.S. Gulf of Mexico. I estimate behavioral models of fishers’ responses to a prospective incentive-based intervention, and find evidence that such a policy could improve multiple fishery outcomes. Second, I perform an ex post program evaluation of an invasive species bounty program. My results suggest that the program underperformed because it failed to overcome countervailing incentives. Together, my case study analyses reveal the value of modeling for designing policy for these complex SES and show the importance of accounting for the full set of system feedbacks (including the incentives that drive recreator behaviors and the impacts of those behaviors) when managing nature-based recreation.
ContributorsJungers, Brenna (Author) / Abbott, Joshua K (Thesis advisor) / Leonard, Bryan (Committee member) / Anderies, John M (Committee member) / Bair, Lucas S (Committee member) / Arizona State University (Publisher)
Created2023
Description
This thesis encompasses a comprehensive research effort dedicated to overcoming the critical bottlenecks that hinder the current generation of neural networks, thereby significantly advancing their reliability and performance. Deep neural networks, with their millions of parameters, suffer from over-parameterization and lack of constraints, leading to limited generalization capabilities. In other words, the complex architecture and millions of parameters present challenges in finding the right balance between capturing useful patterns and avoiding noise in the data. To address these issues, this thesis explores novel solutions based on knowledge distillation, enabling the learning of robust representations. Leveraging the capabilities of large-scale networks, effective learning strategies are developed. Moreover, the limitations of dependency on external networks in the distillation process, which often require large-scale models, are effectively overcome by proposing a self-distillation strategy. The proposed approach empowers the model to generate high-level knowledge within a single network, pushing the boundaries of knowledge distillation. The effectiveness of the proposed method is not only demonstrated across diverse applications, including image classification, object detection, and semantic segmentation but also explored in practical considerations such as handling data scarcity and assessing the transferability of the model to other learning tasks. Another major obstacle hindering the development of reliable and robust models lies in their black-box nature, impeding clear insights into the contributions toward the final predictions and yielding uninterpretable feature representations. To address this challenge, this thesis introduces techniques that incorporate simple yet powerful deep constraints rooted in Riemannian geometry. These constraints confer geometric qualities upon the latent representation, thereby fostering a more interpretable and insightful representation. In addition to its primary focus on general tasks like image classification and activity recognition, this strategy offers significant benefits in real-world applications where data scarcity is prevalent. Moreover, its robustness in feature removal showcases its potential for edge applications. By successfully tackling these challenges, this research contributes to advancing the field of machine learning and provides a foundation for building more reliable and robust systems across various application domains.
ContributorsChoi, Hongjun (Author) / Turaga, Pavan (Thesis advisor) / Jayasuriya, Suren (Committee member) / Li, Wenwen (Committee member) / Fazli, Pooyan (Committee member) / Arizona State University (Publisher)
Created2023
Description
Dear reader, I hope you will read this entire dissertation. If you are reluctant because of its length, I invite you to contact me for a conversation instead. Over the past eight years I have been a part of three unfolding histories: colonialism, sustainability science, and the Atlas of Creative Tools (the Atlas). In this dissertation I describe how I am a part of these histories. I advocate for partnering them so that the Atlas is used by people in the field of sustainability science to advance cognitive justice in their work. This advocacy is supported by research conducted using a mixed-methods approach. I combine qualitative methods used to study each of the three histories with the experiential knowledge I gained from being a part of them. Throughout the dissertation I move back and forth between academic research and experiential knowledge. Each informs the other. This back-and-forth movement is itself a method to interrogate the assumptions of dissertation writing. My purposes for doing so are two-fold. I want to honor the dissertation as a form of knowledge production that can promote cognitive justice while also pointing out how it hinders it. Additionally, the back-and-forth interrogation method involves using creative tools from the Atlas in the text itself. This demonstrates how the Atlas can be used to promote cognitive justice while producing knowledge in sustainability science. I structure this dissertation to aid you in four ways. First, I provide a view of sustainability science as a contested space that people can and do use to advance cognitive justice. Second, I write about my research and analysis of the Atlas so that my descriptions can be used right away by other practitioners who are working with the Atlas. Third, my methods for interrogating the dissertation itself are meant to be used, modified, and built on by others. Finally, I hope that the connections I make between the Atlas and sustainability science are helpful for your work, and that they inspire you to try the Atlas and see how you can use it to promote cognitive justice in your own contexts.
ContributorsNock, Matthew (Author) / Haglund, LaDawn (Thesis advisor) / Manuel-Navarrete, David (Thesis advisor) / Lerman, Elizabeth (Committee member) / Arizona State University (Publisher)
Created2023
Description
Human activity, such as industrialization and deforestation, have led to an increase in global temperatures and natural disaster events that have resulted in the death of over two million people and an economic loss of over USD $3.64 trillion in the last 50 years. Governments, organizations, and activists across the globe have tried to reduce the collateral consequences of human activity on the planet; however, even with increased attention to these issues, there has yet to be much discussion of accountability for planetary harm. Greenhouse gas emissions, waste dumping, and climate change mostly result from individuals, corporations, and governments exploiting the planet of its natural resources freely, without direct and immediate consequence. In the field of criminal justice, the criminalization of and penalization for engagement in certain acts is meant to deter harmful acts. Therefore, to deter auto-genocide, one must ask whether perpetrators of global harm should be held accountable, and what accountability might look like in these scenarios. This article explores traditional definitions of “crime,” punishment, and the criminal label, and discusses the possibility of holding perpetrators of ecocide and the impending auto-genocide accountable utilizing a restorative justice framework.
ContributorsMenes, Norliyana (Author) / Henson, Abigail (Thesis advisor) / Chamberlain, Alyssa W (Committee member) / Blount-Hill, Kwan-Lamar (Committee member) / Arizona State University (Publisher)
Created2023
Description
Political polarization, or the inclination to align with the identity, ideologies, and candidates of a party that results in subsequent partisan animosity that creates divisions between these groups, can prevent important policies from getting passed. Policies related to sustainability, defined as that which “meets the needs of the present without compromising the ability of future generations to meet their own needs,” have been found to be particularly vulnerable to polarization (Brundtland, 1987). This research analyzes literature and expert interviews to provide recommendations and strategies that can be employed by sustainability advocates to get important policies passed despite the divisive political arena. The research concluded that public salience of sustainability issues, presentation of the co-benefits of sustainability policies, relationships amongst elected officials, and use of politically neutral language are especially important to garnering bipartisan support for sustainability policies. Based on these conclusions, strategies were recommended for sustainability advocates to use to overcome political polarization including bolstering communication skills to demonstrate how people are affected by sustainability issues and can benefit from sustainability policies and giving careful and continuous consideration to the words, phrases, and labels used to describe sustainability policies. A final recommendation is to examine political polarization and sustainability at the municipal level since this research indicated that this is a relatively under-examined context.
ContributorsBarlett, Riley (Author) / Melnick, Rob (Thesis director) / Kay, Braden (Committee member) / Barrett, The Honors College (Contributor) / School of Geographical Sciences and Urban Planning (Contributor) / School of Sustainability (Contributor)
Created2023-12