35967 research outputs found
Sort by
Highly Versatile Aerial-Terrestrial Robot - PogoX: System Design and Efficient Data-Driven Control
No full textThe versatility of hybrid aerial–terrestrial robotic platforms continues to highlight their potential for general-purpose mobility across complex and unstructured environments. However, the diverse dynamics in distinct aerial and terrestrial locomotion modes, have placed critical challenges for existing platforms. The first fundemantal challenge is designing elegant and efficient, most existing work try to add extra actuation for ground locomotion, which imposed challenge to aerial mobility. The other is on the control side, most of them struggle to robustly manage contacts, either continuous or impact-driven interactions.
In this thesis, we introduce PogoX, a highly integrated hybrid robot capable of agile flying, efficient wheeled skating, and dynamic hopping. To cope with hybrid dynamics and modeling uncertainty, we develop a unified data-driven predictive controller that augments model-based strategies to compensate the modeling error across modes.
Finally, We combined the reference steering framework with our design, and experimentally validate the system with agile motion and stable control in each locomotion mode. The results demonstrate that PogoX performs effectively in all three modes, showcasing its potential as a general-purpose hybrid mobility platform
Observing the truth: Recording Earth’s changing flow of energy
No full textThe receipt of energy within our atmosphere is the fundamental driver of the climate system. Our ability to accurately measure this exchange of energy and establish a reliable understanding of its trend and variability is fundamental to comprehending the current state of Earth’s climate. This dissertation presents three novel assessments of Earth energy budget observations: trends in the polar top-of-atmosphere solar absorption and thermal emission, constraining atmospheric energy transport from observations, and examining the covariability of energy flux components and meridional energy transport.Satellite observations reveal that decreasing surface albedo in both polar regions is increasing the absorption of solar radiation, but the disposition of this absorbed energy is fundamentally different. In the Arctic, the rates of increasing absorbed solar radiation and thermal emission are remarkably similar (0.98 and 0.94 Wm-2 dec-1 respectively), with solar absorption variability explaining two thirds of the annual thermal emission variability.Conversely, Antarctic thermal emission is not responding to the increasing (though not yet statistically significant) solar absorption of 0.59±0.64 Wm-2 dec-1 with less than a third of the annual thermal emission variability explained by accumulated solar absorption. The Arctic is undergoing rapid adjustment to increasing solar absorption resulting in no change to the net energy deficit, while increasing Antarctic solar absorption represents additional energy input into the Earth system being taken up by the Southern Ocean.To close the atmospheric energy budget, the meridional transport of energy must be recorded, representing the net energy moved by winds across a latitude circle. Here, a method for calculating energy transport from observed energy fluxes is presented, calculated as the integral (accumulation) of the net energy input into the atmosphere from one pole to the other. Observations tend to underestimate annual mean energy transport compared to reanalysis, attributed to reduced poleward gradients in the observed surface turbulent heat fluxes. There is however, close agreement in the variance with correlations of up to 0.8 and 0.5 in the midlatitudes and tropics respectively between calculations. The observed energetic framework presented here facilitates a novel assessment of the energetic fluxes consistent with energy transport variability.Variability in the meridional heat transport is associated with net energy gains andlosses within approximately ±15° either side a latitude band. Anomalous gradients of atmospheric latent heating is the most important term for describing the variability of midlatitude heat transport. Enhanced evaporation within the tropics provides an excess of energy which is then transported poleward and lost through all energy fluxes, radiation, turbulent fluxes, and the atmospheric tendency. The atmospheric tendency (the storage of energy in the atmosphere) is the most important component for heat transport into the polar regions through the convergence of energy transport which is not immediately lost from the atmosphere. These results provide a benchmark for assessing variability in the climate system with the use of observations
Deliberation, Rational Agency, and Responsibility for Belief
No full textIn this paper, I examine Richard Moran’s claim that a believer implicitly takes her beliefs to be a product of her rational agency. This commitment, on Moran’s view, is a direct consequence of the believer’s assumption that her acts of deliberation determine her beliefs. I will show that having such an implicit assumption would not just require a believer to be responsive to questions about the justifiability of her beliefs. She would also be obliged to actively consider the import of any new information that might challenge one of her beliefs, even if she does not know which belief is impugned. I argue that such a requirement is implausibly demanding, and that we should reconsider whether holding a belief really implies as strong a set of commitments as Moran suggests it does
Dendritic Corrosion in Power Electronic Modules by Sulfur-bearing Gases
No full textPower electronic modules are critical to the function of industrial products such as motor drives and power converters used in many different manufacturing processes and environments. When the environment contains elevated humidity and sulfur-bearing gases, the modules can be susceptible to a corrosion failure mode consisting of electrically conductive copper sulfide dendrite filament growth across insulative ceramic trenches inside the module. Processes containing this type of detrimental environment can be wastewater treatment, tire manufacturing, and oil refining, amongst others. Over time, growth of dendritic filaments can cause damage by electrical current leakage, shorting, and arcing leading to unplanned process downtime and safety hazards.This research investigates the corrosion failure mode within modern commercial power electronic modules and provides for the first time a corrosion mechanism hypothesis based on the critical influence of the insulative ceramic surface condition within the trench regions, ie. pores, crevices, and surface roughness. This was made possible through thermodynamic and corrosion reaction considerations identified by experimental testing which aligned with field observations and models. The experimental work included the development of a safe and rapid test method to analyze commercial power modules and explore various thermodynamic and kinetic aspects of the dendrite formation mechanism. Additionally, commercially-produced power modules from several companies were used to characterize the core ceramic materials and relate structural and topographical aspects to corrosion performance and provide direction for mitigation techniques. A highly effective mitigation technique was developed in this work based on bonding of a low melting bismuth-zinc-borate oxide glass partition along the center of the insulative ceramic trenches, imparting an 8X increase on average in time to dendritic filament growth across the insulative trench compared baseline samples. Another technique explored was laser surface modification of the insulative ceramic surface which imparted an improvement of 3.5X increase on average in time to dendritic filament growth across the insulative trench compared baseline samples. This work provides practical benefits of increased reliability of power electronic modules for productive and safe manufacturing operations in humid sulfur-bearing gas environments. With ever-increasing dependence on electrification worldwide, interest in this topic and technology is expected to rise.2026-05-1
Weevils 101: How Does Biocontrol of Eurasian Watermilfoil Work?
No full textWeevils 101: How Does Biocontrol of Eurasian Watermilfoil Work
Genres of Conversation
No full textThe QUD model is largely situated in the dominant pragmatic tradition that takes conversation to be a kind of cooperative information exchange. However, it fails to account for participants’ behavior outside this idealization. We do not just cooperatively exchange information with others—we argue with our opponents; we exchange greetings with coworkers; we are interrogated by a nosy friend or neighbor; we tell jokes to friends and family, etc. In this paper, I aim to refine the QUD model to account for these behavioral differences. I will do so by shedding more light on an often neglected aspect of the QUD model—domain goals—and their interaction with the QUD. I argue that participants’ domain goals account for their behavioral differences. Domain goals are what participants aim to achieve in conversation and the world more generally, and these constrain how participants act in conversation and engage with the QUD. The fact that behavioral differences in conversation are explained by participants’ domain goals also gestures to something significant: our conversational activities should be tied to what I will call the genre of conversation. That is, a proper understanding of conversational activities must tie such activities to a specific genre. We have compelling reasons for thinking so: (i) it allows us to say why some conversational activities are more natural than others, while also supporting our expectations about how other participants will behave; and (ii) it allows us to say why the meaning of certain speech acts, e.g., utterances, vary depending on the genre. While my account of conversational dynamics makes significant progress in accounting for the nuances that the basic QUD model overlooks, there remains a host of questions ripe for serious attention but which I do not have the space to address, of which I mention a few in the Conclusion.2027-05-3
EQUITABLE LEARNING IN ENVIRONMENTAL EDUCATION FOR STUDENTS WITH DISABILITIES
Get PDFThe data collected reflects inconsistencies about understanding strategies for serving diverse learners. This raises questions about the gap between an organization’s self-perception versus demonstrated and/or observable performance on supporting learners with different needs and abilities, as well as the gap in industry knowledge necessary to do so. Overall, research indicates a strong demand for improved equity and differentiated engagement for students with disabilities in environmental education, and it is essential that EE institutions look at developing effective programming that can create better outcomes for this demographic of learners.The purpose of this study is to identify the status and needs of EE institutions across Wisconsin, with special consideration to diversity, equity, and inclusion (DEI) initiatives, and efforts to center and service students and audiences from marginalized communities, including but not limited to those with disabilities. A survey was created to collect both quantitative and descriptive data related to EE pedagogy, areas for improvement, institutional practices, content and curriculum, DEI efforts, and staff training. Quantitative data was analyzed using Qualtrics, and descriptive data was analyzed thematically by the research team, with special consideration to observable trends or themes. This survey was distributed via email in January 2023 to leaders and staff from 112 EE organizations across the state of Wisconsin. The survey was open six weeks, and 65 responses were collected by the end of the window, amounting to a 58% overall response rate. Based on the results of the data, many of the environmental education institutions in the state did not align instruction to any learning standards, nor connect learning to standards reflected in traditional classrooms. Nearly a third of respondents note that their EE organization provides opportunities for differentiated learning, none said they make adjustments to content, process, or product. Despite this, over half of the participants indicated that their EE organization was considerate to the needs of diverse learners when engaging students in programming, and that learners with exceptional needs are valued in outreach materials. This data demonstrates inconsistencies between the services that respondents indicate are offered at their EE organization for learners of varying ability, and the perception that their EE organization is capable of providing effective services to this audience
The Moral Dimensions of the Wisconsin Public Trust Doctrine
No full textSenior Honors Thesis, Department of Legal Studies, University of Wisconsin-MadisonThe Moral Dimensions of the Wisconsin Public Trust Doctrine explores the often-overlooked moral foundations of Wisconsin’s public trust doctrine—a constitutional commitment requiring the state to preserve its navigable waters for public benefit. While typically understood as a technical legal rule or historical remnant, this thesis argues that the doctrine embodies a deeper moral vision rooted in Wisconsin’s cultural identity and democratic values. Drawing on legal philosophers such as H.L.A. Hart, Tony Honoré, and David Schmidtz, the first chapter defines key terms—morality, law, and custom—and examines their interplay. It then proposes that the public trust doctrine should be interpreted not only as a legal norm but as a democratic axiom contributing to the endurance of democracy itself.
The second chapter provides a close textual reading of the Northwest Ordinance of 1787 and the Wisconsin Enabling Act, tracing the doctrine’s legal genealogy. It then analyzes core elements of the doctrine—navigability, state control, riparian rights, and scenic beauty—as expressions of a moral commitment to environmental stewardship and democratic governance. The final section identifies a distinctly “Wisconsinian” morality embedded in the doctrine, one that prizes conservation and participatory government.
Ultimately, this thesis contends that the Wisconsin public trust doctrine is not merely a legal duty but a moral dogma—shaping how Wisconsinites conceive of their relationship to nature, the state, and one another. It offers a compelling case study of how law can function as a vessel for moral values and a shared vision of the common good
Thin Film Annular Flow: Nucleate Boiling and Obstruction Wake Dryout
No full textNucleate boiling in thin film annular flow is a complex phenomenon utilized in many energy systems and is influenced by a variety of heat transfer mechanisms. While the fundamentals are rooted in the comparatively well-understood fields of pool and flow boiling, thin film flow boiling introduces additional challenges that make the heat transfer behavior hard to predict. Considering this, the foundational aspects of nucleate boiling and the relationship between flow parameters – such as liquid film thickness, system pressure, surface tension, channel geometry, mass flow rate, and applied heat flux – and the intensity of nucleate boiling in thin annular films are analyzed and their effects demonstrated. Additionally, recent research has identified disturbance waves as a significant factor in enhancing bubble nucleation, yet the underlying mechanisms driving this phenomenon remain undefined. Therefore, the insights and deficiencies of three theories seeking to explain wave-based nucleation are extensively considered. Furthermore, this work investigates the effect of obstructions under annular two-phase flow conditions flowing through a vertical, upward channel. The flow around a cylindrical obstruction in direct contact with the heated wall, tested with two different diameters, is characterized using high-speed video, temperature measurements, and optically based liquid film thickness measurements. The experiments investigate the flow phenomena over a range of operating conditions from those conducive to nucleate boiling and to those where nucleate boiling is fully suppressed. The results indicate that the obstruction induces sustained film dryout with the size, shape, and number of dryout areas dependent on flow conditions. Additionally, dryout in the wake does not always yield a severe reduction in heat transfer coefficient