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NONLINEAER NUMERICAL SIMULATION STUDY AND REGIONAL-SCALE SEISMIC RESILIENCE ASSESSMENT OF DEFICIENT WOOD-FRAME STRUCTURES RETROFITTED WITH SELF-CENTERING VISCOELASTIC DAMPERS
No full textTimber structures are among the most favorite types for constructing low- to mid-rise buildings. Many older wood-frame buildings were not designed to meet the current seismic provisions, and are considered as wood-frame buildings with soft story deficiency. Such residential buildings with three- and four-story are particularly common in the United States. Recent advancements in seismic design have led to the development of various innovative seismic protection strategies. Notably, the concept of damage-free self-centering systems has garnered significant interest. This approach incorporates a recentering element to restore the structure to its original position and employs fuse devices for energy dissipation, ensuring that the primary structural system remains undamaged during design basis earthquakes.
In this study, new types of retrofitting systems have been developed to overcome the soft-story issue in code-deficient light-frame wood structures. The existing timber soft-story building has been retrofitted using three different systems. In the first phase, the nonlinear seismic behavior of the original unretrofitted building was studied. Then, the existing building has been retrofitted with wood structural panel (WSP) system. In the third phase, the retrofitted building in the previous step was retrofitted on its ground story only with the proposed novel self-centering viscoelastic damper (SCVD) system. Finally, in the next phase, the original unretrofitted wood building has been seismically retrofitted with the state-of-the-art Y-type braced self-centering viscous damper eccentrically braced frame (Y-SCVD-EBF) system providing high lateral stiffness to the deficient wood framed building. The energy dissipation of the developed systems is mainly provided by fluid viscous damper (VD), and TPAD (Trapezoid Plate Added Damping) acts as the backup fuse device. While the system recentering capability is enabled by utilizing preloaded disc springs.
The load-displacement behavior of the proposed self-centering viscoelastic damper (SCVD) systems was analytically derived, and their seismic performance was assessed through nonlinear numerical static and dynamic analyses of the prototype buildings exposed to far-field (FF) ground motions (GMs).
A Python-based framework was used to conduct an intensity-based regional seismic resilience assessment of wood framed soft-story buildings retrofitted with Y-SCVD-EBF systems. The seismic damage and loss assessment follows the FEMA P-58 methodology, with the resilience metrics visualized using a digital twin model in Geographical Information System (GIS) software. As a case study, the regional seismic resilience of over 2,000 wood-frame residential buildings retrofitted with Y-SCVD-EBF systems was studied in San Francisco
REBUILDING LIVES: ARCHITECTURE TO SOLVE AFFORDABLE HOUSING AND HOMELESSNESS CRISIS
No full textHomelessness and affordable housing are critical issues that require urgent attention due to their deep connections with economic, social, and policy factors. In Norfolk, Virginia, the lack of affordable housing has contributed to a rise in homelessness, with 20.1% of the population facing severe housing challenges in 2023. Areas like Ghent once considered “slums, have experienced gentrification, leading to increased rents and a shortage of affordable options. The pandemic has worsened this crisis, highlighting the need to explore the relationship between affordable housing and homelessness. By studying Norfolk’s cultural history, we can inform effective solutions, such as revising policies to encourage affordable housing development and exploring homelessness housing options. Addressing these interconnected social and economic problems is vital to developing solutions, including temporary solutions like tent cities and more transitional solutions such as prefabricated modular housing systems to be used to develop supportive housing. These approaches can help create opportunities to encourage a more equitable society where everyone has the chance to thrive, which is a step to a more inclusive and resilient society
DESIGN PROBES FOR AI−DRIVEN AAC: ADDRESSING COMPLEX COMMUNICATION NEEDS IN APHASIA
No full textAI offers key advantages such as instant generation, multi-modal support, and personalized adaptability—potential that can address the highly heterogeneous communication barriers faced by people with aphasia (PWAs). We designed AI-enhanced communication tools and used them as design probes to explore how AI's real-time processing and generation capabilities—across text, image, and audio—can align with PWAs’ needs in real-time communication and preparation for future conversations. Through a two-phase “Research through Design” approach, eleven PWAs contributed design insights and evaluated four AI-enhanced prototypes. These prototypes aimed to improve communication grounding and conversational agency through visual verification, grammar construction support, error correction, and reduced language processing load. Despite some challenges, such as occasional mismatches with user intent, findings demonstrate how AI’s specific capabilities can be advantageous in addressing PWAs’ complex needs. Our work contributes design insights for future Augmentative and Alternative Communication (AAC) systems
PROTECTOR OF THE REFORMED: OLIVER CROMWELL’S RELIGIO-POLITICAL MOTIVES AND THE DEVELOPMENT OF PROTECTORATE IDEOLOGY
No full textThis dissertation situates the actions of the Cromwellian Protectorate (1653-58) into an evolving construct of power for the expansion and innovative use of the office of Lord Protector to further the aims of those at its core. Specifically, this dissertation centers four principal areas of Protectorate development to illustrate this expansion. First, the religious protection of the Piedmont Protestants put the Reformed conception of history into political action and demonstrated the projected power of the Protectorate to intervene into European affairs in aid of co-religionists. Second, the collection of a large sum of money on the Piedmont Protestant’s behalf demonstrated the Protectorate’s administrative power and economic strength. Third, the shift from the aid for the Piedmont Protestants to beleaguered Protestants of central Europe illustrates a further extension of the Protectorate’s projection of strength which combined with the potential for military alliance but also competition with other strong Protestant forces. Finally, the renewed push for colonial strength demonstrated the Protectorate’s desire for a wider imperium to aid in its claims of European supremacy. Finally, the words and actions of the Lord Protector himself are scrutinized within this framework. The kingship question, too, is assessed from the legal perspective of the MPs assembled to judge the limits and possibilities of both the office of the king and the office of the Lord Protector. As each of these examples illustrate, the Protectorate sought to develop a novel locus of power in the office of the Lord Protector and sought to further their influence and power both in Europe as the head of a Reformed Protestant alliance and in the colonial Atlantic via the realignment of power towards the metropole. Each of the actions described work towards the development of a Protectorate ideology as each function in a developing system of Protectorate governance in unique but connected ways across foreign, domestic, and imperial policies. This Protectorate ideology defeated the ideology of the Commonwealth as the interests of specific parties, namely those of the Army and of the wealthy merchant class that helped to enable the Protectorate, came to dominate many of those favoring Parliament’s enhanced role at the end of the Civil Wars
An Exploratory Analysis of Campus Engagement with Library GIS and Data Services
No full textMcKeldin Library's GIS and Data Services team provides a variety of geospatial- and data science-related services to the UMD community, including one-on-one consultations, technical support, and educational workshops. To better understand the team's patron base and the potential impact of location on the reach of our services, we conducted an exploratory analysis on our transaction intake data, combining spatial and non-spatial methods to generate insights. We discovered that most of our patrons' departments were reachable within a 5-min walking distance, with dramatic drop-offs occurring at 10- and 15-min thresholds. In addition, two important "hotspots" of activity were identified: the Architecture building and the Hornbake/Plant Sciences complex
THE WHEELS ON THE BUS FELL OFF: THE RISE AND FALL OF COURT-ORDERED BUSING IN PRINCE GEORGE’S COUNTY, MARYLAND
No full textThis study examines the desegregation of Prince George’s County Public Schools and the use of court-ordered busing from 1972 to 1998. As Prince George’s was the only county in Maryland under a federal mandate to integrate, this study explores how residents responded to desegregation and the shifting perceptions of busing over the 25 year period of implementation. After a federal lawsuit in 1972, the county was forced to bus students away from their neighborhood school to ensure every school had a racial balance of black and white students. Perceptions shifted with the shifting demographics driven by black suburbanization and a burgeoning black middle class. Between 1970 and 1990, the county transformed from a sleepy, white, rural county into the wealthiest black-majority county in the United States. After the transformation, the perceptions of court-ordered busing flipped, as many black students were being bused to majority black schools. The new black majority gained political power in the 1990s and took charge of local government to end court-ordered busing themselves. Overall, this study pushes back on previous scholarship that deemed court-ordered busing to be a failed tool of desegregation. It argues that while not perfect in achieving integrated schools, it was a necessary federal intervention for Prince George’s County to dismantle its system of segregation and pursue an equitable education for all students
An Inquiry into Honor
No full textOur everyday encounters with honor suggest that it is a largely positive notion. Such examples might include honoring one’s parents, referring to a judge as ‘Your Honor’, or a soldier receiving the Medal of Honor for extraordinary battlefield valor. Unfortunately, honor also has its share of problematic associations. Historically, honor has close ties to violence, social hierarchies, oppressive ideologies, and a base desire for public approval. Consequently, despite its initially positive appeal, there is little support for honor as a notion that should be permitted to govern our modern social interactions. My dissertation is an inquiry into the philosophically underexplored notion of honor for the purpose of defending honor against such views. In Chapter 1, I offer my provisional account of honor as the respect to which the member of an honor group is entitled according to that person’s reputation, which is determined by his adherence to the group’s shared honor code. My account is not intended to be comprehensive; instead, these four stipulated features serve to facilitate an examination of the most significant objections to honor.
In Chapter 2, I explore these pressing objections: first, that honor enables a host of morally objectionable practices; second, that honor promotes problematic social hierarchies; and third, that its essential connection to reputation deprives honor of moral significance. I argue that each of these objections is misplaced. Accordingly, a denial that honor is unfit to govern the interactions of individuals in our society on the basis of any of these objections is inappropriate.
Finally, in Chapter 3, I argue that what makes honor special is its unmatched ability to promote a group’s values and ideals. Honor demonstrates this ability in three ways: acting as a distinct form of motivation, aiding in the projection of our values, and enabling moral resilience. In virtue of honor’s value, as constituted by these three features, honor can be a benefit not only to the groups that utilize honor, but also to the society in which these groups are located
BRIDGING LIGHT WITH DEEP LEARNING: ALGORITHM, COMPILER, AND APPLICATIONS
No full textDeep neural networks (DNNs) have demonstrated significant potential in addressing a wide range of intelligent tasks. However, traditional neural networks deployed on digital platforms face inherent limitations in terms of throughput, computational speed, and energy efficiency, particularly in resource-constrained environments. To address these challenges, a more scalable, faster, and energy-efficient approach is needed for the advancement of deep learning. Optical neural networks (ONNs), which utilize light signals instead of electrical ones as the information carrier for computation, offer such a promising alternative. Among ONNs, free-space diffractive optical neural networks (DONNs) stand out for their high throughput, light-speed computation, and exceptional energy efficiency. They enable all-optical computing at near-light speed by manipulating information-encoded light signals through optical phenomena such as propagation, diffraction, and phase modulation. By leveraging trained passive optical elements, DONNs perform computation without additional energy consumption during all-optical inference.
However, the development and practical deployment of DONNs face several critical challenges. First, the lack of hardware-software co-design algorithms impedes the seamless realization of DONNs, from conceptual design to physical fabrication with analog optical components. Second, the absence of robust emulation frameworks limits system-level applications of DONNs, as designing and exploring DONNs require extensive cross-disciplinary expertise, posing significant technical barriers. Third, current computing engines for DONN emulation and training are computationally intensive, lacking both optimized computing kernels and domain-specific language (DSL) support tailored to ONNs that balances flexibility and maintainability. Fourth, the accessibility of DONN research is limited, necessitating the development of an open-source design infrastructure to facilitate broader community engagement and innovation.
Targeting the improvements and contributions to the development of DONNs, this dissertation presents four key contributions. First, we propose a physics-aware differentiable co-design algorithm designed specifically for DONN systems, enabling the efficient and accurate system training and design automation. Second, we conduct physics-aware optical adversarial investigations, which uncover unique optical security vulnerabilities in ONNs and provide insights into adversarial robustness applicable to other complex-domain systems. Third, we develop an open-source, end-to-end agile design framework, LightRidge, for DONN systems. This framework integrates efficient co-design algorithms, accurate yet high-performance optimized computing kernels, and user-friendly DSL support. It offers a seamless design-to-deployment workflow, bridging the expertise gap for cross-disciplinary research for DONNs. Fourth, we explore DONNs across diverse deep learning applications, including physics-aware multi-task learning, optical-inspired graph learning, and optical-inspired image processing. These applications demonstrate the capability of DONNs for real-world applications and enrich the research landscape of DONNs
The Military as an Institution for the Development of Human Capital
No full textSince the establishment of the all-volunteer force in the United States, the impact of military service on service members has been a critical policy consideration. While earlier research focuses on the negative economic returns to conscription (Imbens and Klaauw, 1995; Angrist, 1990) newer studies underscore the positive returns to volunteer service (Greenberg et al., 2022). This dissertation helps to understand these outcomes by analyzing the mechanisms of human capital development within the U.S. military, focusing on mentorship, training, and personnel assessment. In the first chapter, I leverage an established identification strategy (Lyle and Smith, 2014; Carter et al., 2019) where first-term enlisted soldiers are conditionally randomly assigned to specific supervisors. By analyzing Army ratings data, I show that junior officers learn about 10% of their management style from their initial supervisors. The second chapter explores how military assignments influence geographic mobility. By leveraging quasi-random assignment of a soldier’s first duty station (Carter and Swisher, 2020), I estimate that soldiers assigned away from their home regions are about 5 percentage points more likely to undertake long-distance moves after service with initial evidence suggesting this mobility correlates with increased future income. In chapter three, I analyze shortcomings in subjective performance ratings using a unique longitudinal dataset. After correcting for individual fixed effects, I am able to identify precise biases in ratings. I conclude by using simulation techniques to recommend policy solutions to these problems
WITH NEVER ENOUGH HAPPENING: THE PROCESS OF EMBODYING MATERIALS, CHOREOGRAPHING TEXTILES, AND DESIGNING COSTUMES THROUGH THE PROCESS OF DANCE MAKING AND PERFORMANCE
No full textwith never enough happening is a 30-minute interdisciplinary performance that explores the use of materials, textiles, and costumes and their ability to perform and be performed. This dance, alongside this paper, integrates theory and practice, embodiment and materiality, and costume and choreography while positioning identity and cultural perspective within the discourse. By embedding a cultural perspective, this research offers an expanded view of materiality, embodiment, and resourcefulness in choreographic practice. Upon completing this paper and defending its contents, Daniel came to understand he had used Rasquachismo (a Chicano/a aesthetic) as a framework to gather and organize its content. Rasquachismo, a practice of resourcefulness and making the most from the least, shaped his approach. Not as a way to minimize the labor or significance of the work, but as a way of assembling and repurposing the writings, materials, and choreographies developed and co-created over the course of two and a half years. This realization provides both a foundation and direction for future creative and scholarly work