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Influence of Aerothermoelasticity on Performance of Oblique Detonation Wave Engines
No full textThis is the paper from a presentation given at AIAA SciTech Forum 2025 on 01/08/2025.Oblique Detonation Wave Engines (ODWEs) possess high prospects as an airbreathing propulsive system for high-speed vehicles due to shorter combustor length, high specific impulse, and high specific heat release. However, thin compliant panels used in compression ramp, over which oblique detonation waves are stabilized, are susceptible to aerothermoelastic oscillation. This study investigates aerothermoelastic response of the compression ramp and its effect on total pressure recovery and combustion efficiency of the ODWEs using coupled fluid-structure interaction (FSI) simulations at two distinct temperatures (298 K and 500 K) and a coupled fluid-thermal-structure interaction (FTSI) simulation. Using preCICE coupling library, a partitioned approach to multiphysics simulations is used to couple in-house OpenFOAM-based compressible reacting flow solver: rhoCentralReactingFoam with thermo-structural solver: CalculiX. The ramp oscillated around a constant mean position in FSI simulations while the mean position continuously shifted downwards in the FTSI simulation due to thermomechanical deformation and thermal degradation of the ramp material caused by transient diffusive heat transfer. In all FSI and FTSI simulations, total pressure recovery and combustion efficiency showed a strong positive and negative correlation respectively with the ramp’s displacement. A maximum of 39.5% increase in total pressure recovery and a 9.5% decrease in combustion efficiency was observed due to aerothermoelastic deformation of the ramp. Heat flux at the reattachment region increased due to an increase in wall temperature while heat flux decreased towards the ramp’s tip due to the effect of the ramp’s downward displacement. This highlights the need for an effective thermal protection system, especially in the reattachment region. A study on damping characteristics showed that an increase in wall temperature from 298K to 500K in FSI simulations reduced the damping ratio of the oscillations by about 2 times while it reduced by a factor of about 2.5 after simulation time of 20 ms in FTSI simulation. FTSI simulation for extended physical time is suggested to fully characterize flutter tendencies as the temperature increases
Under Different Canopies: Government Commitment to Urban Tree Preservation
No full textThese are the slides from a presentation given at 2025 The American Society for Public Administration on 03/31/2025.Urban tree canopy cover (TCC) provides valuable services, from air purification and temperature regulation to enhancing community spaces and mental well-being. While this resource takes decades to grow, it can be suddenly lost due to human actions or environmental events. This study investigates factors influencing canopy cover change over a five-year period in 1,838 U.S. cities. Leveraging a national dataset, the analysis assesses whether local government initiatives systematically influence local TCC outcomes in the short-term. During the study period, 63 percent of cities experienced net TCC loss, while the remainder experienced overall gain. Regression results highlight distinct factors influencing canopy cover between these groups. For example, housing development and environmental stressors drove variation in cities experiencing net loss, not gains. Similarly, government factors associated with TCC preservation in cities with net loss versus gains. These insights underscore the need for targeted short-term interventions to support tree canopy maturation and preservation
The Human Geography of Small Kansas Cities: A Status Report
No full textKansas is a predominantly rural U.S. state with hundreds of small cities. A review of the scholarly literature reveals a lack of studies on the human geographical issues of small Kansas cities. Therefore, a review of the popular literature was conducted, which reveals many serious economic, demographic, and environmental issues with these cities. Based on the reviews, it is concluded that there is a need for more studies on the human geography of small Kansas cities to understand many existing and emerging issues affecting these cities
SLANT: A Starter Strategy™ for Class Participation (2nd Edition)
No full textThis research was published by the KU Center for Research on Learning, formerly known as the University of Kansas Institute for Research in Learning Disabilities.Teachers have long recognized the importance of students active participation in class. Students who participate learn more and teachers who work with these students find teaching to be more rewarding. The SLANT Strategy has been designed to enable students to participate in class in appropriate and productive ways. Students who master SLANT understand why it’s important to actively participate during class and how to do so. The five steps of the strategy are:
S = Sit up
L = Lean forward
A = Activate your thinking
N = Name key information
T = Track the talker
Before you can light students’ intellectual fire, you must have their attention. Teaching the SLANT Strategy is not only a really good way to gain students’ attention but is also a great way to introduce students to the concept of strategies and their benefits. Within a few minutes, students can learn the five basic steps of this simple little strategy that will help them become active participants in any class discussion and better learners
Sankofa: A relic of transatlantic slave trade and a conciliator of Pan-Africanism
No full textThese are the slides from a presentation given at the Thesis Defense held in Bailey Hall, RM 109 on 04/09/2025The borders of West Africa reveal the relics of interactions held among European countries and Africa through the notorious trade ‘transatlantic slave trade’. This trade took place along the shores of Sierre Leone, Gambia, Senegal, Ghana, Nigeria, Togo, and Benin, where indigenes were taken captive, kidnapped, pawned, and subjected as defaulter debtors, who were finally sold as slaves. The study employs a qualitative research approach, employing content analysis as a means of data collection. Hence, I will use “Assin Manso, Elmina, Cape Coast, and Fort William, as slave trade centers to emphasize the tragic and horrific sentiments the enslaved underwent and their relevance to contemporary Africans and the diaspora. Using Interpretative theory, this study will apply diaspora studies as the principal technique to investigate Sankofa and Pan-African ideas as means of cultural reconciliation. Sankofa will be interpreted as a philosophical term to symbolize the connection between African Americans and present-day Ghanaians drawing on elements of ‘Africaness’. The study will further utilize Haile Gerima’s ‘Sankofa’ to interpret the relationship between the past, present, and future of African Americans, and Africans, specifically looking at contemporary Ghanaians as the study unit, demonstrating their fragmented history and Pan-nationalist goals, fostering healing, reconciliation, and reintegration into African community. This paper will reveal the significance of ‘Sankofa’ through Gerima’s adaptation of Sankofa, the symbolism of Sankofa at slave sites (Elmina, Cape Coast, Forts William and Amsterdam and Assin Manso) to express diaspora reactions of their ancestry, and the contemporary function of the Year of Return to both the diaspora and Ghanaians
Understanding hydrolysis energy on amorphous silica surface
No full textThis poster was presented on March 25, 2025 at the National Conference of the American Chemical Society, held in San Diego, California.In spite of its wide use as support in heterogeneous catalysis, accurate atomically detailed models of amorphous silicates have been elusive to-date. Amorphous silica, which is composed of SiO4 tetrahedral units in the form of siloxane rings of different sizes, shows local structural disorder and surface heterogeneity that play a key role in its reactivity. Although it is difficult to identify and understand the distribution of catalytically active sites and their structures from experimental characterization, density functional theory (DFT) simulations allow us to probe the properties of the individual sites. In this contribution, cluster models of amorphous silica are used to study the thermodynamics of the functionalization reaction on the silica surface. We investigate the variation of functionalization energy with the structural parameters of the unfunctionalized site, which are defined as descriptors. We use the random forests regression model to determine the most important descriptor(s) that correlates with the functionalization energy. Considering the different combinations, a two-descriptor set composed of rL (longest Si-O bond at the site) and θP (difference between the smallest and largest angles of the unfunctionalized ring) provides the lowest average root mean square error (RMSE), which is still 30% of the average functionalization energy in magnitude. While increasing the size of the data set should improve the machine learning fitting and reduce the RMSE, modelling large clusters is computationally expensive. Thus, for a quantitative simulation of the reaction we attempt to produce minimal models of the site of functionalization that effectively mimic the results of the large clusters. We truncate (and cap the dangling bonds with F atoms) or relax (and freeze the surroundings) the original large clusters. Repeating the calculations by increasing the radii of truncation (or relaxation) of the clusters from the functionalization site, it is seen that the energy changes with increase in size of the clusters until it converges. These results show that not only the local coordination environment but the bulk of amorphous silica significantly affect the functionalization energy
Native Plant Signage and Education: How Botanical Belonging Expands Plant Access in the Local Community
No full textThis capstone was submitted in partial fulfillment of the requirements for EVRN 615, taught by Dr. Kelly Kindscher and Dr. Ali Brox.Despite the importance of native plants in local ecosystems, an underutilized space for their application resides in household gardens and residential areas. While these plants are overlooked for countless reasons, a leading contributor is the lack of education surrounding their importance and implementation. The difficulty of sourcing and transitioning residential gardens to include native species leads many individuals to avoid growing these plants despite their incredible benefit to maintaining a diverse ecosystem and improving ecological health. Public education starts on a small scale and Botanical Belonging, a native plant nursery in Tonganoxie, Kansas, hopes to be a native plant resource for both new gardeners, and experts alike. By working with Botanical Belonging, we can gauge the current community knowledge of native plants and contribute to expanding this education on a local level. Engaging with community members at the organization’s native plant sales will provide valuable data on how best to direct further education in future work. If native plants continue to be ignored by the average homeowner, their implementation will become more difficult as current ecological problems become exacerbated. By providing basic information on these plant species through new signage and collecting data on consumers' knowledge, we hope to supplement Botanical Belonging's educational practices. While the current implementation of native plants is severely lacking in urban and residential spaces, expanding the availability of educational material will inspire a greater appreciation of native species and their benefits
Moving Beyond Mapping: A Guide to Ecosystem Measurement
No full textIn this paper, we argue that equipping ecosystem builders, leaders and community champions with more rigorous methods, such as network analysis, for measuring their impact potential is crucial to driving systems change at scale. We advocate for moving beyond simply mapping an ecosystem to measuring it. This means adding rigor to your efforts by quantifying an ecosystem’s strengths and challenges, its structure and functioning, the influencers and the outliers, and the dynamic interrelationships that exist. These aspects are what matter for ecosystem science
There’s a New Crown in Town: Synthesis and Characterization of a Uranyl Complex Supported by a Nitrated Crown Ligand
No full textThis work was submitted in partial fulfillment of the requirements for the degree of Bachelor of Arts with Honors in Chemistry.By studying the manner in which the uranyl ion interacts with various types of ligand systems, fundamental chemical insights can be obtained which could lead to innovation in the fields of radiochemical separations and nuclear fuel reprocessing. Such innovations could be developed into technologies for supporting a cleaner world and greener energy system. In this thesis, the synthesis and characterization of a novel aza-crown ligand and its uranyl-containing counterpart are outlined, along with electrochemical analysis and crystallography. The ligand is a member of a new class of aza-crown ligands for uranyl coordination that are being synthesized by the Blakemore Group at KU, and the derivative described in this thesis is unique as it is appended with nitro groups. The uranyl complex was prepared with straightforward synthesis procedures, and nuclear magnetic resonance (NMR) data provide evidence of the presence of multiple conformational isomers in solution. Among these isomers, there is a minor 3% component which could correspond to non-crown-encapsulated species. The metal-free ligand undergoes a quasi-reversible, two-electron reduction with a half-wave reduction potential of –1.56 V vs. the ferrocenium/ferrocene couple, corresponding to reduction of each nitro group. Scanning anodically reveals an amine-centered oxidation near +0.7 V and a paired follow-up reduction feature at –1.1 V. Both the nitro-centered reduction(s) and amine oxidation appear during electrochemical analysis of the uranyl complex, the data for which feature an additional chemically reversible U(VI/V) reduction at a rather positive half-wave potential of –390 mV. Considering all this, the uranyl complex described here appears to afford ready access to unique redox chemistry, including formation of U(V) species featuring ligand radicals derived from the nitro groups found on the ligand substituents. Built on the current foundation of results, future work is planned to chemically and electrochemically interrogate the properties of the radical species that can be generated on this new platform
Three Ps in a Pod: The Quantification of Lewis Acidity using Phosphine Oxides and the Synthesis and Immobilization of Molecular Uranyl Complexes bearing Polycyclic Aromatic Hydrocarbons onto Pyrolytic Graphite-based Electrodes
No full textThis undergraduate thesis was submitted to the Department of Chemistry in Partial Fulfillment of the Requirements for the Degree of
Bachelor of Science with Honors.This thesis discusses two different research themes. Chapter 1 describes the quantification of Lewis acidity using different phosphine oxide probe molecules. Triethyl (E), trioctyl (O), and triphenyl (P) phosphine oxides were selected as probes to investigate trends in the Lewis acidity of a wide range of mono-, di-, and trivalent metal cations. 31P{1H} titration data collected in MeCN revealed that all three probes bind to Na+ and K+ with 1:1 stoichiometry, whereas they bind to Li+, Ba2+, Sr2+, and Ca2+ with greater than 1:1 stoichiometry, as shown by data fitting to the Hill-Langmuir equation. The titration data differ in dynamic range, with E and O displaying a significantly larger dynamic range than P. In all cases, Δδ′max values from full titrations with K+, Na+, Li+, Ba2+, Sr2+, and Ca2+ were linearly correlated with the pKa values of the corresponding [M(OH2)m]n+ which suggests that Lewis acidity in water has a corresponding relationship with effective Lewis acidity in MeCN measured by the three phosphine oxide probe molecules studied in the course of the work described here. Chapter 2 describes the synthesis, characterization and surface immobilization of molecular uranyl complexes bearing different polycyclic aromatic hydrocarbon (PAH) groups. The PAH groups chosen for this study were 1-naphthyl, 2-naphthyl, and 9-anthracenyl. The modular synthetic route used to incorporate the PAH groups afforded the desired uranyl complexes in pure form, as indicated by 1H NMR and elemental analysis. The structures of two of the complexes were confirmed by single-crystal X-ray diffraction analyses as well. Vibrational and electronic absorption spectroscopy were used to further interrogate the electronic and structural properties of the complexes. The surface immobilization of the uranyl complexes was demonstrated through both surface electrochemistry and X-ray photoelectron spectroscopy