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Description
Special thermal interface materials are required for connecting devices that operate at high temperatures up to 300°C. Because devices used in power electronics, such as GaN, SiC, and other wide bandgap semiconductors, can reach very high temperatures (beyond 250°C), a high melting point, and high thermal & electrical conductivity are required for the thermal interface material. Traditional solder materials for packaging cannot be used for these applications as they do not meet these requirements. Sintered nano-silver is a good candidate on account of its high thermal and electrical conductivity and very high melting point. The high temperature operating conditions of these devices lead to very high thermomechanical stresses that can adversely affect performance and also lead to failure. A number of these devices are mission critical and, therefore, there is a need for very high reliability. Thus, computational and nondestructive techniques and design methodology are needed to determine, characterize, and design the packages. Actual thermal cycling tests can be very expensive and time consuming. It is difficult to build test vehicles in the lab that are very close to the production level quality and therefore making comparisons or making predictions becomes a very difficult exercise. Virtual testing using a Finite Element Analysis (FEA) technique can serve as a good alternative. In this project, finite element analysis is carried out to help achieve this objective. A baseline linear FEA is performed to determine the nature and magnitude of stresses and strains that occur during the sintering step. A nonlinear coupled thermal and mechanical analysis is conducted for the sintering step to study the behavior more accurately and in greater detail. Damage and fatigue analysis are carried out for multiple thermal cycling conditions. The results are compared with the actual results from a prior study. A process flow chart outlining the FEA modeling process is developed as a template for the future work. A Coffin-Manson type relationship is developed to help determine the accelerated aging conditions and predict life for different service conditions.
ContributorsAmla, Tarun (Author) / Chawla, Nikhilesh (Thesis advisor) / Jiao, Yang (Committee member) / Liu, Yongming (Committee member) / Zhuang, Houlong (Committee member) / Jiang, Hanqing (Committee member) / Arizona State University (Publisher)
Created2020
Description
This thesis explores conservation of threatened and endangered species in the Phoenix metro area using social media. With increased urbanization, rising temperatures, and other issues occurring in the desert landscape, creatures big and small face devastating losses in their populations. Informing the public about the species currently on the brink of extinction allows people to identify the animals in the wild, and may encourage conservation practices that would allow wildlife to thrive far into the future. Utilizing social media as a tool for spreading awareness permits information about Arizona wildlife to be free and easily accessible. This project consists of interviews with conservationists and social media influencers, a survey to understand online behaviors and identify level of interest in the different species, and the creation of consumable social media infographics about the threatened and endangered species of Phoenix. Instagram was selected by survey respondents as the platform they would follow conservation accounts on, leading to the creation of @phxconservation to post the social media infographics. Best practices found by posting on social media in this project can be useful information for conservationists looking to build engagement and effectively inform people.
ContributorsDavitt, Stephanie (Author) / Larson, Kelli (Thesis director) / Quick, Jazzy (Committee member) / Barrett, The Honors College (Contributor) / Walter Cronkite School of Journalism and Mass Comm (Contributor) / School of Sustainability (Contributor)
Created2021-12
Description
Social-ecological systems (SES) are replete with hard and soft human-made components (or infrastructures) that are consciously-designed to perform specific functions valued by humans. How these infrastructures mediate human-environment interactions is thus a key determinant of many sustainability problems in present-day SES. This dissertation examines the question of how some of the designed aspects of physical and social infrastructures influence the robustness of SES under global change. Due to the fragility of rural livelihood systems, locally-managed common-pool resource systems that depend on infrastructure, such as irrigated agriculture and community forestry, are of particular importance to address this sustainability question. This dissertation presents three studies that explored the robustness of communal irrigation and forestry systems to economic or environmental shocks. The first study examined how the design of irrigation infrastructure affects the robustness of system performance to an economic shock. Using a stylized dynamic model of an irrigation system as a testing ground, this study shows that changes in infrastructure design can induce fundamental changes in qualitative system behavior (i.e., regime shifts) as well as altered robustness characteristics. The second study explored how connectedness among social units (a kind of social infrastructure) influenced the post-failure transformations of large-N forest commons under economic globalization. Using inferential statistics, the second study argues that some attributes of the social connectedness that helped system robustness in the past made the system more vulnerable to undesirable transformations in the current era. The third study explored the question of how to guide adaptive management of SES for more robustness under uncertainty. This study used an existing laboratory behavioral experiment in which human-subjects tackle a decision problem on collective management of an irrigation system under environmental uncertainty. The contents of group communication and the decisions of individuals were analyzed to understand how configurations of learning-by-doing and other adaptability-related conditions may be causally linked to robustness under environmental uncertainty. The results show that robust systems are characterized by two conditions: active learning-by-doing through outer-loop processes, i.e., frequent updating of shared assumptions or goals that underlie specific group strategies, and frequent monitoring and reflection of past outcomes.
ContributorsYu, Jae Hoon David (Author) / Anderies, John M. (Thesis advisor) / Janssen, Marco A. (Committee member) / Muneepeerakul, Rachata (Committee member) / Arizona State University (Publisher)
Created2015
Description
A process plan is an instruction set for the manufacture of parts generated from detailed design drawings or CAD models. While these plans are highly detailed about machines, tools, fixtures and operation parameters; tolerances typically show up in less formal manner in such plans, if at all. It is not uncommon to see only dimensional plus/minus values on rough sketches accompanying the instructions. On the other hand, design drawings use standard GD&T (Geometrical Dimensioning and tolerancing) symbols with datums and DRFs (Datum Reference Frames) clearly specified. This is not to say that process planners do not consider tolerances; they are implied by way of choices of fixtures, tools, machines, and operations. When converting design tolerances to the manufacturing datum flow, process planners do tolerance charting, that is based on operation sequence but the resulting plans cannot be audited for conformance to design specification.
In this thesis, I will present a framework for explicating the GD&T schema implied by machining process plans. The first step is to derive the DRFs from the fixturing method in each set-up. Then basic dimensions for the features to be machined in each set up are determined with respect to the extracted DRF. Using shop data for the machines and operations involved, the range of possible geometric variations are estimated for each type of tolerances (form, size, orientation, and position). The sequence of manufacturing operations determines the datum flow chain. Once we have a formal manufacturing GD&T schema, we can analyze and compare it to tolerance specifications from design using the T-map math model. Since the model is based on the manufacturing process plan, it is called resulting T-map or m-map. Then the process plan can be validated by adjusting parameters so that the m-map lies within the T-map created for the design drawing. How the m-map is created to be compared with the T-map is the focus of this research.
In this thesis, I will present a framework for explicating the GD&T schema implied by machining process plans. The first step is to derive the DRFs from the fixturing method in each set-up. Then basic dimensions for the features to be machined in each set up are determined with respect to the extracted DRF. Using shop data for the machines and operations involved, the range of possible geometric variations are estimated for each type of tolerances (form, size, orientation, and position). The sequence of manufacturing operations determines the datum flow chain. Once we have a formal manufacturing GD&T schema, we can analyze and compare it to tolerance specifications from design using the T-map math model. Since the model is based on the manufacturing process plan, it is called resulting T-map or m-map. Then the process plan can be validated by adjusting parameters so that the m-map lies within the T-map created for the design drawing. How the m-map is created to be compared with the T-map is the focus of this research.
ContributorsHaghighi, Payam (Author) / Shah, Jami J. (Thesis advisor) / Davidson, Joseph K. (Committee member) / Ren, Yi (Committee member) / Arizona State University (Publisher)
Created2015
Description
This dissertation presents a new methodology for the sustainable and optimal allocation of water for a river basin management area that maximizes sustainable net economic benefit over the long-term planning horizon. The model distinguishes between short and long-term planning horizons and goals using a short-term modeling component (STM) and a long term modeling component (LTM) respectively. An STM optimizes a monthly allocation schedule on an annual basis in terms of maximum net economic benefit. A cost of depletion based upon Hotelling’s exhaustible resource theory is included in the STM net benefit calculation to address the non-use value of groundwater. An LTM consists of an STM for every year of the long-term planning horizon. Net economic benefits for both use and non-use values are generated by the series of STMs. In addition output from the STMs is measured in terms of sustainability which is quantified using a sustainability index (SI) with two groups of performance criteria. The first group measures risk to supply and is based on demand-supply deficits. The second group measures deviations from a target flow regime and uses a modified Hydrologic Alteration (HA) factor in the Range of Variability Approach (RVA). The STM is a linear programming (LP) model formulated in the General Algebraic Modeling System (GAMS) and the LTM is a nonlinear programming problem (NLP) solved using a genetic algorithm. The model is applied to the Prescott Active Management Area in north-central Arizona. Results suggest that the maximum sustainable net benefit is realized with a residential population and consumption rate increase in some areas, and a reduction in others.
ContributorsOxley, Robert Louis (Author) / Mays, Larry (Thesis advisor) / Fox, Peter (Committee member) / Johnson, Paul (Committee member) / Murray, Alan (Committee member) / Arizona State University (Publisher)
Created2015
Description
Human behavior is driving many sustainability problems, which means that resolving these issues will require far more people to participate in solutions and act in sustainable ways. However, there is a recognized gap between knowledge and action that remains a significant barrier in achieving transformative sustainability solutions. One way to overcome the knowledge-action gap is to engage more people in place-based experiential learning centered around sustainability. In partnership with Hawai‘i Tropical Bioreserve & Garden (HTBG), we set out to learn about utilizing place-based experiential learning to engage a wider audience to actively participate in sustainability solutions. We researched place-based learning, experiential learning, sustainability education, and behavior change theory. We also conducted several informational interviews with experts in environmental education, STEM, and sustainability science to better understand what is needed for designing meaningful educational experiences that inspire action. We used this research to develop an easily understandable and scalable place-based experiential learning framework that can teach learners about any sustainability challenge or solution. Overall, we found that when grounded in behavior change theory and sustainability principles, place-based experiential learning has the potential to mobilize large groups of people to actively participate in sustainability solutions.
Created2021-04-28
Description
Islands are some of the smallest contributors to global carbon emissions, yet are among the most vulnerable to the impacts of climate change (e.g. rising sea levels, extreme storms, and declining fish populations due to warming seas). At the same time, due to their smaller scale and local limitations on resources, island communities have been driving adaptation efforts for responding to the impacts of climate change based on their lived experiences and indigenous knowledge. Recognizing that local community members are in the best position to advance sustainability solutions in their respective island communities, our project sought to uncover best practices of islands that are collaboratively working with their communities to promote sustainable development and adapt to climate change, while leading the way in measuring progress on the SDGs. To this end, we interviewed island leaders from Hawaii, Guam, and Tasmania, who have already launched strategies for achieving these goals, and combined their experiences into a framework requested by other island leaders to encourage locally-driven, culturally-relevant green growth initiatives in partnership with our project partner, the Local2030 Islands Network (Local2030IN). Through designing the framework, we learned 17 possible actions islands can take when developing their own green growth initiative, key insights for implementing the SDGs on islands, and how to work alongside a project partner to create a final deliverable.
Created2021-04-28
Description
Journalism is one of the most far-reaching mediums to inform the public about environmental and sustainability issues. Mass communication has brought this discussion to an unprecedented level of exposure that continues to escalate, and the quality of storytelling must continue to spark discussion about sustainability and environmental problems. The quality of environmental journalism, the “researching, verifying, writing, producing and broadcasting of news about the environment” to and for the public sphere, has been a subject of much debate (Pezzullo & Cox, 2012). This beat, relatively new, is an emerging one that serves the public by explaining the importance of protecting and preserving the environment. However, sometimes journalists’ work falls on deaf ears. In order for environmental journalists to be effective storytellers with robust, reliable work that resonates with audiences, they must continue to improve the effectiveness and captivating qualities of their work.
This project will explore how the American public perceives environmental reporting, constraints on its production, an assessment of the industry’s success and growth, and advice from current journalists. I will conclude with a list of the best practices for captivating and effective storytelling. Finally, I will close with a reflection based upon my creative project, a multimedia piece on how citrus crops in Arizona are affected by honey bees. I aim to provide student journalists with an informal guide to the key skills that will help them excel not only in reporting on a certain sustainability topic, but also on the environment as a whole.
This project will explore how the American public perceives environmental reporting, constraints on its production, an assessment of the industry’s success and growth, and advice from current journalists. I will conclude with a list of the best practices for captivating and effective storytelling. Finally, I will close with a reflection based upon my creative project, a multimedia piece on how citrus crops in Arizona are affected by honey bees. I aim to provide student journalists with an informal guide to the key skills that will help them excel not only in reporting on a certain sustainability topic, but also on the environment as a whole.
ContributorsHenne, Sarabeth Baxter (Author) / French, Lynn (Thesis director) / West, Maureen (Committee member) / Walter Cronkite School of Journalism & Mass Comm (Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
I have been studying both Supply Chain Management and Business Sustainability during my undergraduate at Arizona State University. This paper has allowed me to further explore some of the topics that I was introduced to during my time studying at ASU. For my supply chain alternative thesis, I attended multiple interesting faculty research presentations in the Supply Chain department and wrote reflections on each. The presentations were used to help choose a topic to focus on in the rest of my thesis. It is the third research seminar that I attended by Barbara Flynn, titled Understanding Adaptation to a Sustainability Technology Innovation: Longitudinal Outcome Trajectories, that sparked my interest in further researching sustainability in supply chains. The second portion of this paper contains a literature review of papers and journals on the topic of sustainability within supply chains over the last decade. Studies on this topic are becoming more popular as concerns with global warming increase. My research mainly consisted of reading journals and articles on ways that sustainable practices can be applied to reduce the environmental impact of businesses. This paper focuses on recent sustainability trends found across different areas of the supply chain, including: supplier selection and engagement, manufacturing, building efficiency, and logistics.
ContributorsSchneider, Chris (Author) / Printezis, Antonios (Thesis director) / Vitikas, Stanley (Committee member) / Department of Supply Chain Management (Contributor) / Dean, W.P. Carey School of Business (Contributor) / Department of Information Systems (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
The objective of this study was to evaluate sustainability knowledge and practices in place at university-associated food pantries across the United States. A survey was sent to university- associated food pantries and responses were collected at a rate of 25% (n=84 of 326) to assess the knowledge and practices of this topic. The pantries surveyed were chosen solely based on ability to contact through email (emails were retrieved from online sources) and about 50% of the 680 university-associated pantries in the United States were sent the survey. The data was analyzed by quantifying the qualitative responses to the 9 sustainability- rated questions addressing zero- waste practice, barriers to offering sustainably sourced foods, types of sustainable donations, desire for sustainable products, and client demand for sustainable products and practices were posed to pantries. Results from this study provided insight into awareness of sustainability in these pantries and also assessed what sustainability practices are already being practiced by these pantries. Among those surveyed, a low percentage of university-associated pantries actually provide sustainably sourced foods (9.5%), but given the choice about a third (38.1%) would choose to offer these foods. It was reported that availability and cost were perceived as main barriers to providing sustainably sourced foods and that a small proportion of pantries teach their clients about zero waste practices, compost, and recycling. There is little client concern about this issue. Most pantries reported recycling more often than composting and also reported participating in some zero-waste practices. These results are unique to this study as not much research has been done in this area to assess environmental sustainability awareness in university-associated food pantries. Further research is required to further evaluate pantries across the nation as this sample size is approximately 12% of all university- associated pantries in the United States.
ContributorsCrowe, Alexandra B (Author) / Bruening, Meredith (Thesis director) / Payne-Sturges, Devon (Committee member) / School of Life Sciences (Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05