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High-Throughput Experiments and Reliability Assessment of 3-D Printed Bistable Mechanical Metamaterials connected in series
No full textBistable mechanical metamaterials, structures with two mechanically stable states, offer promising potential for deployable, energy-efficient, and adaptive systems in aerospace, robotics, and biomedical engineering. However, their design optimization remains challenging due to geometric nonlinearity, sensitivity to boundary conditions, and manufacturing inconsistencies. Moreover, how these materials interact and perform as a system, whether configured in series or in parallel, is still not well understood. This work introduces a comprehensive, high-throughput framework for the design, fabrication, testing, and optimization of 3D-printed bistable metamaterials, aimed at studying the behavior of them as a system and enhancing performance and reliability. A horizontal experimental setup was developed to rapidly characterize multiple bistable unit cells connected in series under uniaxial tension and compression, significantly reducing the time and effort required for mechanical testing. Structures were fabricated using PLA and TPU and designed with varying ligament geometries, Q values, and unit cell architectures to systematically explore the parameters influencing bistability. High-throughput testing revealed key insights into snap-through forces, hysteresis, and the influence of gravity, friction, and alignment on load distribution. Notably, increasing TPU beam thickness shifted the bistability threshold, while frictional inconsistencies across the test rail introduced variability, especially in larger assemblies. Finite element simulations in Abaqus complemented the experiments, accurately capturing nonlinear deformation and snap-through behavior. The simulations enabled deeper analysis of stress localization, energy barriers, and bistability windows, aligning well with experimental trends and informing design sensitivity. Together, the experimental and numerical findings provide a scalable strategy for rapid bistable metamaterial evaluation, offering actionable design guidelines to improve consistency, reliability, and performance in adaptive structural applications
Vietoris–Rips Complexes of Torus Grids
Get PDFIn this work, we study the homotopy types and homology of Vietoris–Rips
complexes of torus grid graphs. Let T_{n,n} be a torus grid graph consisting of n × n points
on T2 equipped with the l1 metric. We first compute the homology of VR(T_{n,n}; k) for
1 ≤ n ≤ 28 and 1 ≤ k ≤ 13. Subsequently, we provide a complete classification of the
maximal simplices in VR(T_{3k,3k}; k) for k ≥ 2, VR(T_{3k−1,3k−1}; k) for k ≥ 3, and VR(T_{n,n}; k)
when k ≥ 2 and n ≥ 3k. Using these classifications, we establish the homotopy equivalences:
VR(T_{3k,3k}; k) ≃ V_{6k^2−1} S2 for k ≥ 2, VR(T_{3k−1,3k−1}; k) ≃ V_{6k−3} S2 ∨ V_{6k−2} S3 for k ≥ 3, and
VR(T_{n,n}; k) ≃ T^2 when k ≥ 2 and n ≥ 3k
The structure and electrical activity of the tentacular apparatus of the ctenophore Mnemiopsis leidyi
No full textCtenophores have garnered considerable interest in evolutionary biology due to molecular phylogenetic studies that have positioned Phylum Ctenophora as the sister taxon to all other animals. Mnemiopsis leidyi, one of the most studied ctenophore species, possesses a complex tentacular apparatus essential for feeding and likely mediating diverse sensory functions. This dissertation focuses on elucidating the morphological and bioelectrical properties of this critical organ system. In Chapter 1, I describe the previous and current state of understanding of this enigmatic organ and provide some background regarding the phylogenetic position of Phylum Ctenophora. In Chapter 2, we present a detailed morphological analysis of the tentacular apparatus, resolving prior ambiguities and proposing an updated model for tentilla dynamics, including growth, distribution, transport, and recycling mechanisms. Chapter 3 explores the ultrastructure of the tentacular bulb, identifying distinct functional regions and anatomical specializations, while also documenting the presence of presumed apoptotic cells that suggest that active cellular remodeling is ongoing. Chapter 4 establishes nine staging criteria for M. leidyi metamorphosis, capturing key morphological transitions in the tentacular apparatus, unexpected mechanisms of tentacle modulation and modification and revealing unexpected reverse developmental activity. Chapter 5 introduces the first extracellular recordings from the tentacular apparatus of M. leidyi, uncovering spontaneous, endogenous rhythmic electrical waves that propagate through the tentacular structure and across the epithelial surface. Lesion experiments reveal that multiple sources are likely to generate and support spontaneous firing, although the tentacular bulb likely acts as a central pacemaker or oscillator that coordinates and drives rhythmicity. Altogether, these related studies resolve longstanding uncertainties in the anatomy of M. leidyi’s tentacular apparatus and provide a structural and functional framework for future studies. My work offers novel insights into signal generation and coordination in this, the most common ctenophore in the Atlantic Basin. This work advances our understanding of the resiliency of the ctenophore nervous system and laying groundwork for future behavioral studies; it may also provide insight into the bases for the enormously invasive activity of this animal in the world’s coastal seas
The Influence of Support Systems on the Career and Family Decisions of Female Music Faculty in Higher Education
Get PDFThe purpose of this quantitative study was to explore the influence of support systems on
the career and family decisions of female music faculty in higher education. Data was gathered
from an anonymous survey and participants were female faculty in higher education in the
United States within the music profession. A theme that emerged from participants’ responses
was the profound influence having a supportive partner or spouse had on their decisions
regarding career and family. Approximately half of participant responses indicated having a
supportive partner enabled them to pursue their career and/or have children. Some participants
responded having close friends or extended family was also very influential in their ability to
pursue their desired career, but friends and family were not mentioned in any responses as
influential in decisions regarding having children. Having children has often been reported as a
major obstacle for women who desire to achieve tenure (Anders, 2004; Armenti, 2004; Bovin,
2020; Frye, 2003). My survey revealed only 32.4% felt their career had significantly influenced
their decision not to have children with 41.2% responding their career had “not at all” influenced
this decision. Most tenured faculty (71.8%) had at least one child and most (72.7%) reported
their first child was born either before they were tenured or before their academic career. Only
7.6% reported having their first child after tenure was achieved. This contradicts what Armenti
(2004) found that younger female faculty felt it was better not to have children prior to tenure.
Another significant finding was 80.2% of participants felt they have to work harder than their
male colleagues to achieve the same level of recognition; 75.9% felt their gender has caused bias
within the workplace; and 62.9% felt they have been discriminated against because of their
gender
A Cognitive Hierarchical Framework for Multivehicle Collision-Free Traffic Management of Unregulated Intersections
No full textAutonomous vehicles are becoming increasingly popular, requiring efficient and reliable methods for trajectory generation and path planning. A common approach is to convert the original continuous-time optimization problem into a discrete-time parametric optimization problem, but consider only a set of control/action variables, which can limit the feasibility and generality of the generated trajectories. To address these limitations, this thesis proposes an approach to autonomous collision-free vehicle trajectory optimization using model predictive control (MPC) with a continuous range of control inputs. The considered formulation enables the computation of more accurate and dynamically feasible paths for autonomous vehicles.
A key challenge in path planning of autonomous vehicles is to account for not only the presence of other vehicles, but also their trajectories. More specifically, the other vehicles must be treated as dynamic obstacles and collision-free trajectories have to be generated. Naturally, one has to take into account and model vehicle-to-vehicle interactions and incorporate such interactions, in terms of state path constraints, as part of the formulation of trajectory optimization problems. We leverage Cognitive Hierarchy Theory, specifically using level- game theory, to predict the behavior of other vehicles/agents, which affects their trajectories. This framework provides a structured way to anticipate interactions and make informed decisions for designing collision-free trajectories.
For testing the proposed framework, an unregulated crossroad was simulated with two vehicles approaching it at the same time. The conducted experiments were split into two sets of scenarios: with and without the level estimator enabled, which allows one vehicle to change the reasoning depth over the course of simulations.
Numerical results demonstrate that the proposed approach is both feasible and effective in capturing realistic vehicle interactions and in generating collision-free trajectories. The level-k game-theoretic modeling enhances the decision-making capabilities of autonomous vehicles, leading to safer and more efficient navigation. These findings highlight the potential of expanding the set of control actions in improving autonomous vehicle trajectory planning
Stratigraphic and Structural Controls on a Carbon Sequestration Reservoir in Shelby County, Alabama
No full textThis study evaluates the suitability of the fold-and-thrust belt in Shelby County, Alabama,
for carbon storage, focusing on its structural and lithological integrity. Orogenic events in the
region have thickened the strata, forming unique structural features known as mushwads
(Malleable, Unctuous SHale, Weak-layer Accretion in a Ductile duplex), which can reach several
thousand feet in thickness. The Lower Paleozoic strata, primarily the Knox Group, are identified
as potential reservoir rocks due to their fractured carbonate composition. As determined of this
study, the porosity and permeability of these crystalline carbonates are highly dependent on
fractures resulting from orogenic processes.
Characterization was conducted using data from three regional wells: ARCO/Anschutz #1,
Westover #1, and Westover #2. These wells provided 49 thin sections for analysis, along with
associated cuttings. To assess the regional structure, three seismic lines were acquired, capturing
both strike and dip profiles. Additionally, X-ray diffraction analysis of the Copper Ridge Dolomite,
a Knox Group member selected as the target formation, provided geochemical insights.
A potential sampling bias is acknowledged due to the inability to create thin sections from
fractured samples. However, given the samples of this study, tight carbonates, both observed and
calculate, prove as a hurtle for long term carbon dioxide storage. Further research and methods of
the OASIS (Optimizing Alabama’s CO₂ Storage in Shelby County) project group needs to be
conducted to prove the viability of carbon capture and storage in Shelby County, Alabama
Enhancing Construction Stormwater Management Nationwide: A Focus on Design Innovations and Training Programs
Get PDFA study of enhancing construction stormwater management was conducted through the completion of two distinct projects. One project focused on improving technology transfer methods through providing stormwater education and outreach to underserved communities, specifically counties within the Black Belt region of Alabama. The service area encompassed 47 individual U.S. Census Bureau tracts within 17 counties of Alabama. This area has experienced a population migration out of the area due to a lack of opportunities. In fact, populations in the service area are less than 2,500 and have median household incomes well below 80% of the State Non-metropolitan Median Household Income. In addition to socioeconomic disadvantages within the service area, there are also environmental concerns. Alabama is highly vulnerable to erosion and is at high risk for construction stormwater pollution due to the heavy rainfall and erosive soils. The Black Belt region of Alabama had highly fertile soil that led to cotton production, and due to the heavy production of cotton, the topsoil is now depleted which compounds flooding and pooling effects. This project seeks to fill the gap between researchers and practitioners through developing training specific to on-site needs which have been assessed through a state-of-the-practice survey as well as interviews with various county engineers. Common challenges faced by stormwater professionals in the area have been determined which has allowed for the creation of targeted outreach materials.
Overall, this study found that communication with stakeholders is essential for successful transfer. In addition, rural communities have distinct needs that differ from urban communities due their socioeconomic status. Thus, working directly with such communities and involving them in the decision-making process is necessary to provide long-term benefits. Ultimately, working with the service area community members and targeting specific needs are essential for successful technology transfer implementation.
The second project focused on developing recommendations for future volumetric sizing guidance of the live storage component of sediment basins on construction sites. To do so, a study of the long-term performance of four proposed sizing guidance methods for sediment basins compared to two standard designs was conducted using the USEPA SWMM for 150 distinct locations. Such proposed sizing methods include applying a sizing factor of 1,800 ft3 per acre (125 m3 per ha) of disturbed land and calculating the volume of runoff generated using the local 85th, 90th, and 95th percentile precipitation events. The two standard design sediment basins include calculating the runoff generated from the local 2-yr, 24-h storm event and applying the sizing factor of 3,600 ft3 per acre (250 m3 per ha) of disturbed land. The results of the analysis of the original six basins were used to determine the optimal size of a sediment basin for each study location. This optimal design considered the relationship between basin storage volume and runoff capture rate and utilized a method to determine the point at which larger basins result in diminishing returns.
Stormwater runoff from construction sites is a leading cause of environmental degradation, yet sizing guidance for sediment basins lacks scientific justification and relies on industry rules-of-thumb. This study aims to provide scientific justification for sediment basin sizing regulations by investigating the mean percent of live storage volume utilized and the mean percent of overflow through the auxiliary spillway for each proposed sizing method compared to the standard methods.
Sediment basins were designed and sized in Excel for 150 locations across the United States, each with varying annual precipitation amounts. At each location, sediment basins were designed for each of the 4 proposed sizing methods, the 2 standard methods, and each of the tested optimal designs. The geometry data, along with several other parameters, were input into SWMM to run long-term simulations using the local historical precipitation and air temperature data. This project seeks to provide a further understanding of the long-term performance of sediment basins and hopes to both provide future sizing guidance as well as be used as a basis for future testing and analysis of the long-term performance of sediment basins to ensure that a sufficient amount of live storage volume is utilized while ensuring that overflow from the basin is not detrimental to water quality and downstream communities.
Analysis showed that each proposed sediment basin design utilized a statistically higher mean percentage of live storage volume when compared to each standard sediment basin design across the entire simulation period. This means that the standard basin designs may be oversized. In addition, the study found that 120 of the 150 optimal design basins had a VSF of less than 3,600 ft3 per acre (250 m3 per ha), the current USEPA standard. Thus, further testing and analysis may supplement the research conducted in this study to ensure that a sufficient amount of live storage volume is utilized and that overflow from the basin is not detrimental to water quality and downstream communities
Reconstructing Radiations: genomics of diversification in lizards and butterflies
No full textUnderstanding the processes that lead lineages to diversify and give rise to new species is a major driving question in evolutionary biology. The role of extrinsic forces, such as geographic isolation and environmental variation, are both considered important by preventing gene flow,
either due to physical barriers that impede migration or due to local adaptive divergence. In this dissertation, I investigate how environmental variation and geographic isolation have contributed to diversification within two model clades for evolution and ecology research: Anolis
lizards and Heliconius butterflies. Using genome-scale data from hundreds of individuals, I reconstruct the evolutionary histories of these two byproducts of recent divergence and explore patterns of genomic variation to ask how geographic isolation and varying environmental conditions have shaped those histories. First, I focus on the role that environmental variation has played in shaping genomic patterns of divergence among lizards characterized by discordant phenotypic and genetic variation. I find population genomic structure largely corresponds to broad-scale environmental variation on the island of Hispaniola, but show that efforts to detect genomic regions underlying local adaptation are limited by available genomic resources and current methods. Second, accessing much greater breadth of the genome, I reconstruct the evolutionary history of a wide-ranging butterfly found across continental and island habitats to test whether geographic isolation has driven divergence. By using a species tree inference approach, I show that previously inferred phylogenetic relationships may have been confounded by rapid divergence, and find isolated populations to be divergent from their mainland counterparts. Together, these chapters advance our knowledge of the role played by extrinsic forces in shaping genome-wide variation in lineages undergoing divergence
Look What You Made Me Do: Examining Dark Traits and Victimhood Tendencies in Allocation Games
No full textThe current study examined the relationship between Dark Personality, Light Personality, and the Tendency for Interpersonal Victimhood using allocation games. While previous research has established connections between the Dark Tetrad (Machiavellianism, psychopathy, narcissism, and everyday sadism,) the Light Triad (faith in humanity, humanism, and Kantianism,) and behavior in allocation games, this study contributes to the literature by investigating the Tendency for Interpersonal Victimhood (moral elitism, need for recognition, lack of empathy, rumination) and its relationship with these other personality frameworks. To do so, two different allocation games (Dictator's and Ultimatum) with manipulated conditions of context, framing, and resource were used. This study also examined the potential moderating role of Honesty-Humility in allocation behavior. Results provided insights into personality and behavior. The Dark Tetrad, Light Triad, and the Tendency for Interpersonal Victimhood significantly predicted donation behavior on allocation games. Honesty-Humility only moderated the relationship between the Dark Tetrad and allocation behavior. Factors of these allocation games themselves, such as framing, context, and resource, as well as the specific combination of these factors, impacted behavior. This research has important implications for understanding the role of personality in workplace behavior and decision-making, which becomes relevant particularly in leadership and executive positions where Dark traits may be more prevalent
Guidelines of Applying User's Unconscious Behavior to Product Innovation
No full textIn today's rapidly advancing technological era, the speed of product iteration is continuously increasing. In such context, innovation in user experience becomes a crucial aspect of business competition. Designers leverage market feedback and technological advancements to enhance product quality, reduce costs, and shorten development cycles. Product iteration is undeniably key to achieving commercial success. Chapter 1 of this study first describes the current real-world issues. In practice, designers often build on the knowledge of previous products while focusing on commercial objectives during product iterations. This approach has led to the creation of products with overly complex functions and forms, which not only fail to enhance user interaction experience but also increase the user's learning and cognitive burden. Simple, intuitive product interactions that naturally align with users' unconscious behaviors are what users need in a fast-paced daily routine. However, current product design research rarely starts from the user's unconscious behavior to explore product interaction. This study is based on Naoto Fukasawa's Without Thought Design theory, aiming to develop a Design Guideline that utilizes users' unconscious behaviors during product use to innovate and improve existing product interaction designs.
This thesis adopts an inductive approach, deriving a theoretical design guideline through a literature review. Chapter 2: The literature review covers the origins and relevant theories of unconscious behavior, including studies of the collective unconscious in psychoanalysis and consciousness in ecological psychology. It also includes the definition, importance, and design process of product interaction design. Additionally, Chapter 2 provides a comprehensive review of the foundational theories of Without Thought Design. It attempts to analyze these theories through the lens of semiotics and rhetoric. Moreover, Chapter 2 analyzes three types of Without Thought Design, which apply users' unconscious behavior in product interaction in different ways.
Chapter 3 presents the design guideline, highlighting the four key design processes which cover Project Research, Transcribe and Analyze User’s Unconscious Behavior, Apply Design Route, and Design Delivery. It explains how to record and analyze users' unconscious behaviors, determine design routes, and innovate interaction design through these routes, ultimately achieving innovation in user interaction experience.
Chapter 4 applies the theoretical design guideline to a practical design project, using a glue gun pen as an example. It provides a detailed description of the specific product and target user research, collection and analysis of unconscious behaviors, and application of design routes. The practical application of this research is demonstrated through two design concepts.
Chapter 5 summarizes the entire content. Overall, this study aims to bridge the gap between users' unconscious behavior and product design, proposing a design guideline that utilizes users' unconscious behavior for product interaction innovation. This approach not only reduces users' cognitive load but also enhances the user experience