Computing has a history of perpetuating injustices, a pattern that has only seemed to grow worse over recent years. These injustices are a direct result of computing's epistemic values and practices, which suggests the need for computing to adopt alternative epistemic values and practices, including sociopolitical awareness, reflexivity, humility, and an explicit commitment to justice. These are the central values of feminism, but while scholars have developed theories about how feminist values could reshape computing, there is a need for more research into how to practically integrate feminist values into computing practice. Additionally, given that computing education reinforces and reproduces the dominant computing culture, there is a need for further research to imagine how computing education could be transformed to teach developing technologists how to integrate feminist values into this practice. I conducted a small-sample, in-depth interview-based study to understand the experiences of people who are developing into or practicing as feminist technologists. Through my research, I identified six common characteristics of feminist technologists, including a commitment to care, awareness of power structures, practice of epistemic humility, application of systems thinking, and negotiation with the tensions in integrating feminist values. I also identified two common types of experiences that help develop people into feminist technologists: experiences that foster feminist consciousness-raising and experiences that positively model feminist values. These insights suggest alternative ways of understanding the development of feminist technologists as a continuous process, where being and becoming a feminist technologist is one and the same, that requires a foundation of emotional safety.

Halide perovskites are promising materials for tandem solar cell applications due to their easily tunable bandgap through cation and halide variations. However, photo-induced halide segregation in iodide-bromide perovskite chemistries often results in iodine-rich and bromine rich domains that limits the efficiency of tandem solar cells. One approach to mitigate such segregations reported in the literature is the addition of chlorine to the usual iodide-bromide perovskite compositions. With Gaussian process regression and other computational tools, we efficiently explore the cesium-formamidinium triple halide perovskite composition space and optimize for perovskite optical property and stability at the same time.

Research Advisor: Rebecca Belisle, Ph.D., Assistant Professor of Physics, Wellesley College Research Co-Advisor: Zachary del Rosario, Ph.D., Visiting Professor of Engineering, Olin College of Engineering Academic Advisor: Mark Somerville, Ph.D, Provost, Dean of Faculty, Professor of Electrical Engineering and Physics, Olin College of Engineering

We see a misalignment between the engineering field’s constitutive-interests rooted in the reductionist sciences and the needs of the 21st century in the socio-political, environmental, and spiritual realms. Following Habermas’s critical theory, the knowledge-constitutive interest of the natural and reductionist sciences lie primarily in the manipulation of the physical world for the purpose of predictable and quantifiable outcomes by reducing the studied system to its smallest components. Such interests are unfit to understand and intervene in our world; a living world of dynamic complexity. We argue that a renewed science of holism will create the conditions for a critical engineering education that can mimic the properties of living systems to recreate a thriving existence for all living beings on this planet. In this thesis, we identify six loose web-nodes to draw a picture of a science for the whole:

(1) Natural phenomena such as emergence, self-organization, or autopoiesis acquaint us with the nature of nature. (2) The study of our world brings us closer to our cosmos’s mysteries, which naturally introduces spirituality to the holistic web. (3) Dynamically complex systems theory attempts to understand the relationships between parts of the system to make assumptions about future behavior or opportunities for intervention. Practices that are commensurate with the nature of reality are crucial for an effective engagement with living systems. Such practices include (4) methods for a co-creation of the future and (5) research and learning methodologies that embrace unpredictable emergence of insights and emancipate us from hidden oppressive power structures. (6) Lastly, a holistic science includes the reductionist sciences to analyze, predict, and control non-living, simple systems. Our hope is that a holistic science will re-shape engineers’ understanding to learn and interact with our world to recreate the nature of nature in our systems: a thriving existence for all.

Readers are invited to comment on the online version of the thesis: https://drive.google.com/file/d/1C3SCRvH27EgcddZZr0pTxEqCUb41ksqJ/view

| Advisors: Linda Vanasupa, Benjamin Linder, Jonathan Stolk

Diversity in the information people see and attend to can help people and groups make better decisions, can help people learn and correct inaccurate beliefs, and can help people see ideas with which they do not agree as legitimate. Media policy in the United States has long had a focus on promoting audiences’ exposure to diverse information. The rationale for this goal has been that accurate beliefs and perceptions are necessary for good decision-making and for good governance in democratic society, and that development of these accurate beliefs requires some degree of exposure to information that challenges one’s existing beliefs and opinions. The Internet has brought more choice for what news and information individuals can access. Observers have warned that existing media policies are ill-suited for guaranteeing exposure to political diversity in the Internet age, as people are able to choose more freely from an ever-increasing variety of sources, many of which cater to and present a very narrow range of viewpoints. Given this range of choice, they argue, Americans will increasingly live in ideological echo chambers and polarization of different political groups will increase. Republicans and Democrats already read different newspapers and watch different TV news stations. They read different political books. They even live in different places. The sources to which they attend are echo chambers: left-leaning and right-leaning blogs rarely link to each other and comment threads contain little disagreement. If people prefer to avoid hearing challenging views, we may see even greater political fragmentation in information consumption as people get better tools for filtering the news based on their own reactions and reactions of other people like them.

Wetlands offer a variety of services, such as pollutant removal from point and nonpoint sources, flood attenuation, and habitat for biodiversity. Constructed wetlands can be used in agricultural watersheds to protect surface waters from pollution by agricultural activities. A particular concern for the agricultural Midwest is the high nitrate export from agricultural fields that affects water quality at local and regional scales, including hypoxia in the Gulf of Mexico. Nitrogen export primarily originates in the Upper Mississippi and Ohio River Basins. Tiledrained lands, characteristic of west central Indiana, have greater nitrate losses than un-tiled lands. Constructed wetlands have been proposed as a partial solution to intercept nitrate between agricultural lands and downstream waters. In order to most efficiently use constructed wetlands to treat nitrate exported from tile-drained lands, these wetlands should be carefully placed in the landscape to intercept high nitrate loads and sized according to their contributing areas. In this thesis a methodology is presented for strategically placing constructed wetlands in the landscape, and this methodology is applied to an 8-digit hydrologic unit (HUC) in west central Indiana. Results showed 19 sites that are suitable for wetland placement, requiring conversion of 0.1% of the entire 8-digit watershed. These wetlands would intercept approximately 3% of nitrate-rich waters from tiledrained lands, removing approximately 1% of all nitrate exported. To better estimate nitrate removal in these headwater wetlands, the Soil and Water Assessment Tool (SWAT) was applied to a watershed within the 8-digit HUC where three potential wetland sites were found. Simulated wetlands removed nitrate in every month having flow. These three modeled wetlands consistently removed 17-36% of annual incoming nitrate, culminating in a 5% decrease in average nitrate loads at the watershed outlet. If placed strategically, wetlands can efficiently remove nitrate from tile-drained flow, but the extent of their impact in the landscape is dependent on the suitability of local conditions for wetland placement, as well as the specific criteria used for siting wetlands.

We develop an aircraft and control system that is capable of repeatedly performing a high speed (7m/s or 16 MPH) "knife-edge" maneuver through a gap that is smaller than the aircraft's wingspan. The maneuver consists of flying towards a gap, rolling to a significant angle, accurately navigating between the obstacles, and rolling back to horizontal. The speed and roll-rate required demand a control system capable of highly precise, repeatable maneuvers. We address the necessary control theory, path planning, and hardware requirements for such a maneuver, and give a proposal for a new system that may improve upon the existing techniques.

Due to variations in donations and volunteer support, maximizing effectiveness is crucial to the survival of nonprofit organizations. This project evaluates the ability of Six Sigma, TQM, ISO 9000 and Malcolm Baldrige criteria to help a small nonprofit in the healthcare industry better manage its processes. Six Sigma is the framework selected as it is straightforward, small-organization friendly, exhibits timely results, and is quick to implement. The Six Sigma DMAIC methodology is applied to the nonprofit to define the organizational stakeholders, processes and goals, and then FMEA is used to determine appropriate areas to target for initial corrective actions. Corrective actions are successfully implemented on the area of highest impact, the volunteer feedback form. The DMAIC process used for this nonprofit may be adapted and applied to other nonprofits seeking to begin use of quality approaches.

Abdominal aortic aneurysms (AAA’s) are characterized by a permanent and irreversible enlargement of the abdominal aorta to at least 150 percent its expected normal size. Endovascular treatment of AAA’s with endografts has gained tremendous popularity in the last decade, largely due to decreased perioperative mortality and faster recovery times, when compared to open surgical repair. Although endografts are an appealing treatment option for many patients, some device design and safety issues have yet to be addressed. One of the biggest problems with endografts is their tendency to shift their position in the patient anatomy over time. The forces that cause this shift and their relation to endograft design are not well understood. In addition, the degree of blood damage due to the insertion of an endograft into the abdominal aorta has not been quantified. The following studies were completed in order to investigate the issues described above. 1. Calculation of endograft displacement force in patient-specific device models. This study used electron-beam computed tomography (CT) image data to generate patient-specific anatomical models using novel segmentation techniques. The patient models were then virtually modeled to represent three different endograft designs, based on aortic stent-graft devices already available in the U.S. or currently in clinical trials. Computational Fluid Dynamics (CFD) simulations were run to characterize the hemodynamic factors for each patient and a total displacement force was calculated for each model. Results show that the location of the device bifurcation impacts the overall displacement force, with proximal bifurcation endograft designs generating a lesser force than distal bifurcation designs. 2. Characterization of blood damage due to endograft placement. Patient-specific computational models were created to represent endograft features that partially obstruct blood flow to the renal arteries, which is sometimes necessary to attain complete exclusion of the aneurysm after deploying the device. Findings show that the insertion of an endograft causes a two-fold increase in blood damage. However, the magnitude of blood damage is within acceptable safety standards. 3. Benchtop testing of red blood cell damage. A benchtop experimental setup was created to measure the damage to red blood cells under various flow conditions and flow obstructions. Samples were characterized at different time points using light scatter methods to determine cell volume and hemoglobin concentration. Results indicate that significant damage to red blood cells occurs only after prolonged exposure (>103 seconds) to high shear (>4000 dynes/cm2) conditions. In addition, the presence of flow obstructions creates red blood cell fragments, instead of destroying the cells entirely. Future directions for this work include additional CFD modeling of devices in more patients treated with different aortic stent graft designs to derive statistical significance relative to various design and anatomical features and extend the analysis to the evaluation of devices used for the treatment of thoracic aortic aneurysms (TAA’s). Follow-up studies on device migration studies can also be completed in the cohort of patients where the endograft displacement forces were calculated. Further, blood damage models that incorporate the fragmentation of red blood cells can be developed.

Oceanographic applications of robotics are as varied as the undersea environment itself. As underwater robotics moves toward the study of dynamic processes with multiple vehicles, there is an increasing need to distill large volumes of data from underwater vehicles and deliver it quickly to human operators. While tethered robots are able to communicate data to surface observers instantly, communicating discoveries is more difficult for untethered vehicles. The ocean imposes severe limitations on wireless communications; light is quickly absorbed by seawater, and tradeoffs between frequency, bitrate and environmental effects result in data rates for acoustic modems that are routinely as low as tens of bits per second. These data rates usually limit telemetry to state and health information, to the exclusion of mission-specific science data. In this thesis, I present a system designed for communicating and presenting science telemetry from untethered underwater vehicles to surface observers. The system's goals are threefold: to aid human operators in understanding oceanographic processes, to enable human operators to play a role in adaptively responding to mission-specific data, and to accelerate mission planning from one vehicle dive to the next. The system uses standard lossy compression techniques to lower required data rates to those supported by commercially available acoustic modems (O(10)-O(100) bits per second). As part of the system, a method for compressing time-series science data based upon the Discrete Wavelet Transform (DWT) is explained, a number of low-bitrate image com- pression techniques are compared, and a novel user interface for reviewing transmitted telemetry is presented. Each component is motivated by science data from a variety of actual Autonomous Underwater Vehicle (AUV) missions performed in the last year.