<p dir="ltr">Plant phenotyping is the process of characterization and quantification of physical traits<br>of plants such as height, leaf area, biomass, wilting degree, or flowering time. Many plants<br>become limp or droop through heat, loss of water, or disease. This is also known as wilting.<br>In this thesis, we propose multiple quantifiable wilting metrics that will be useful in studying<br>bacterial wilt and identifying resistance genes. In order to obtain the wilting metrics, we use<br>machine learning methods to identify the center of the stem. We also propose a fast ground<br>truthing method to speed up training data generation. We test our metrics on both tomato<br>plants and soybean plants with wilting caused by either bacteria or drought. We successfully<br>demonstrated that our metrics are effective at estimating wilting in plants.</p><p dir="ltr"><br>Field experiments often comprise thousands of plants. For many Unmanned Aerial Vehi-<br>cles (UAVs) image-based plant phenotyping analyses, we need to examine smaller groups of<br>plants known as ”plots”. We propose a method to extract plots from images acquired from<br>UAVs. In addition, we proposed a system that will allow us to combine our plot extraction<br>results with field data such as plant ID, plant genotype, and experiment type provided by<br>the planters. We also developed a method to generate synthetic plant center location data.</p>

<p>  </p> <p>Articular cartilage is a strong but flexible connective tissue that covers and protects the ends of long bones. Osteoarthritis (OA) is a degenerative joint disease which is the most prevalent type of arthritis. The progression and development of OA involves changes in cartilage composition and tissue degradation. As a result, the biomechanical and biotribological properties of the joint may be affected. It has not been determined how cartilage composition and mechanical properties affect its wear and friction, or if there are feasible strategies to improve cartilage performance.</p> <p>Photochemical crosslinking is one method to enhance the modulus and strength of collagenous tissues and improve their resistance to enzymatic degradation. In chapter 2, the effect of photochemical crosslinking on viscoelastic properties of cartilage using an indentation test were investigated. Results of the study indicated that chloro-aluminum pthalocyanine tetrasulfonic acid (CASPc) photo-initiator and 670 nm light increases the modulus of articular cartilage, though this effect is likely limited to the tissue surface.</p> <p>The objective of research described in chapter 3 was to assess correlations between tissue composition and modulus with friction and wear properties in healthy cartilage specimens. Viscoelastic properties of cartilage were obtained via indentation and then the coefficient of friction was measured during an accelerated <em>in vitro</em> wear test. The composition of adjacent cartilage tissue including collagen, glycosaminoglycans, and pyridinoline crosslinks were obtained by biochemical assays. Correlation analysis suggested that stiffer cartilage with higher glycosaminoglycans (GAGs) and collagen content leads to higher wear resistance of the cartilage. Enzymatic collagen crosslinks in type II collagen, pyridinoline (PYD), also enhances the wear resistance of the collagen network. The three parameters of wear, composition, and mechanical properties of cartilage were interrelated and were all correlated with one another. However, friction was independent of these in healthy cartilage tissue. </p> <p>In chapter 4, the hypothesis that mechanical wear is exacerbated in degraded cartilage tissue was tested. Fresh osteochondral specimens were treated with interleukin-1β, with chondroitinase ABC (ChABC) to specifically remove GAGs, or with collagenase to degrade the collagen network during culture. Viscoelastic properties of the tissues were characterized followed by an accelerated <em>in vitro</em> wear test. Results of this study suggest that although the degradation of cartilage was observed with exposure to IL-1β, ChABC and collagenase, wear was not uniform between the three. All three treatments lost GAGs across their superficial zone, and tissue loss due to wear appeared to be confined to the superficial zone. The passive loss of GAGs did not induce increased wear of the tissue. However, an increase in wear was observed with degradation of the collagen network. As the COF was not affected by the degradative treatments, the changes in wear were attributed to alterations in tissue structure and composition</p> <p>Finally, in chapter 5, conclusions, and summary of all main three chapters were stated and directions for future studies were presented.  </p>

<p>Significant seasonal changes in chemical and microbiological water quality can occur in buildings at different fixture locations due to temperature and time dependent reaction rates. Here, a series of calibrated plumbing hydraulic-water quality models were developed for the extensively monitored Retrofitted Net-zero Energy, Water & Waste (ReNEWW) house in West Lafayette, Indiana USA. Knowledge gaps that inhibited higher resolution water quality modeling were also identified. The eight new models predict the absolute level of free chlorine, total trihalomethanes (TTHM), Cu (Copper), Fe (Iron), Pb (lead), NO₃^–(nitrate-nitrogen), heterotrophic plate count (HPC), and <i>Legionella spp.</i> concentration at each fixture for plumbing use, operational characteristics, and design layouts of the plumbing system. Model development revealed that the carrying capacity to describe Legionella spp. growth (and other organisms) under water usage and plumbing design conditions is lacking in the literature. This information needed for higher resolution modeling. Reducing building water use by 25% prompted increased absolute concentrations of HPC and Legionella, each increasing by a factor of about 10⁵. When the service line length was increased, Legionella spp. concentrations increased by up to 10⁶gene copies /L in the Summer season. The proposed modeling framework can be used to support better planning, design, analysis, and operational decision-making.</p>

<p dir="ltr">Silicon carbide (SiC) is a ceramic with strength retention at elevated temperatures, oxidation resistance and a high thermal conductivity. These properties make SiC a desirable ceramic for compact, high temperature (> 1000 °C), heat exchangers with improved thermal performance. However, fabricating a SiC heat exchanger is difficult due to the low self-diffusion and high melting temperature of SiC. The aim of this dissertation is to show the viability of using co-extrusion and slip casting as low-cost, scalable processes for creating a compact, high temperature, SiC heat exchanger.</p><p dir="ltr">Co-extrusion is an advantageous fabrication technique as it is capable of producing samples with micron-sized features in two dimensions. To fabricate the heat exchanger body via co-extrusion, a SiC-filled polymer blend and a carbon black (CB)-filled polymer blend (sacrificial) were developed. A 54 vol% SiC-filled polymer blend with the addition of 12 wt% alumina and yttria, sintering aids, in a 2:1 ratio, respectively produced samples with the highest relative densities of 94% while maintaining an extrudable rheology. The SiC-filled polymer blend was co-extruded at 80 °C with a 45 vol% CB-filled polymer blend to produce unit cells that were open and continuous after binder burnout and sintering. The unit cells had an average relative density of 90% with an average strength of 165 MPa.</p><p dir="ltr">The unit cell strengths were lower than expected due to the formation of defects that occurred after removal of the polymers. These defects were categorized into macrodelaminations, defects that occur between two laminated unit cells, and microdelaminations, defects that occur within a single unit cell. The mechanisms causing these defects was studied by investigating the lamination and polymer removal processes. Results showed that poor lamination between extrudates mitigated the macrodelaminations and an oxygen-rich debinding atmosphere caused the formation of microdelaminations. Defect-free unit cells were produced though a partial extrusion step and binder removal in a nitrogen atmosphere.</p><p dir="ltr">An aqueous SiC suspension for slip casting was optimized by investigating the rheological properties, zeta potential, and slip casting behavior. It was determined that a suspension with 40 vol% solids, 1.2 wt% dispersant (polyethyleneimine), and a pH of 7.5 resulted in uniform slip cast parts. This optimized suspension was used to fabricate dense, crack-free SiC headers with an average relative density of 96% and an average strength of 266 MPa.</p><p dir="ltr">This dissertation gives insight into important fabrication parameters that must be considered when fabricating high temperature, SiC heat exchanger components. Additionally, this dissertation showcases the capability of using co-extrusion and slip casting as potential pathways for fabricating a high temperature, SiC heat exchanger.</p>

<p dir="ltr">Interactions between drinking water quality and delivery systems, pipe materials, and attitudes</p>

<p dir="ltr">Urban air mobility (UAM) has the potential to revolutionize the transportation industry, offering fast, convenient, and sustainable travel options for passengers and cargo. The development and operation of UAM networks, however, face significant challenges, including the need for infrastructure investments and the management of grid electricity usage. In this thesis, we present a comprehensive model of UAM network operations based on system-of-systems engineering principles and employ a data-driven simulation framework to analyze the expected performance of a UAM operation. Our approach optimizes the composition of the UAM network, including the number of vehicles, chargers, and sizing of solar microgrids, to minimize total acquisition costs while adhering to operational constraints such as maximum average passenger delay and grid usage for each vertiport. Through the application of our methodology to diverse case studies, we provide valuable insights into the optimal design and integration of on-site microgrids for UAM vertiport networks, highlighting their impact on carbon emissions, operating costs, and grid electricity usage. This research contributes to the development of sustainable and efficient UAM systems, supporting informed decision-making among stakeholders involved in the planning, deployment, and operation of urban air mobility networks.</p>

<p>Two-dimensional (2D) halide perovskites are an attractive class of hybrid perovskites that have additional optoelectronic tunability due to their accommodation of relatively large organic ligands. Nevertheless, contemporary ligand design depends on either expensive trial-and-error testing of whether a ligand can be integrated within the lattice or conservative heuristics that unduly limit the scope of ligand chemistries.</p><p>This work begins by investigating simulation-guided ligand design. Employing molecular dynamics (MD) simulations and machine learning (ML) models, systematic ligand exploration unveils the principles governing the stability and structural relationships of these perovskites. Promising ligand candidates undergo a refinement process informed by feasibility considerations, followed by experimental synthesis and characterization to underscore the effectiveness of simulation-informed design strategies.</p><p>Delving into the realm of anionic diffusion, a pivotal factor in 2D perovskite stability, the study examines this property using both experimental methods and simulation techniques. This parallel examination underscores the alignment between simulation predictions and real-world observations, offering nuanced insights derived from molecular simulations. Importantly, simulations serve as potent tools for hypothesis validation when ligands originate from experimental synthesis, affirming conjectures stemming from empirical insightsThe exploration extends to comprehending the molecular insights of experimental observations, thereby shedding light on factors that enhance device efficiency. We explore mechanisms for mitigating phase disproportionation, optimizing ion diffusion, modulating molecular interactions between perovskite and polymeric hole-transporting materials, and uncovering the single-molecule behavior that leads to high photoluminescence quantum yields. Notably, all simulation outcomes align with experimental findings, further validating the utility of MD analysis in the context of 2D perovskite systems.</p><p>Furthermore, this work addresses a crucial aspect of MD simulations, namely the refinement of force field models. Previously developed topology automated fixed-charge force-field interactions (TAFFI) is augmented through the incorporation of polarizability using classical Drude oscillators, resulting in a novel framework termed TAFFI-Drude. This approach enhances electrostatic properties while retaining transferability and consistency from the existing TAFFI model.</p><p>The thesis concludes with a comprehensive discussion of the findings across the aforementioned areas, highlighting the impact of simulation-driven design and insights in advancing 2D perovskite research. The implications of these discoveries for optoelectronic applications and the broader field of materials science are explored, emphasizing the potential for innovation and improvement within the realm of 2D halide perovskites.</p>

<p dir="ltr">In the past decade, magnetic microrobots have gain lots of attention because of their potentials in biomedical applications, such as cell/tissue manipulation, biopsy, and drug delivery. Recent development on materials and microfabrication techniques also provide more opportunities for microrobots. Especially, the emergence of smart polymers that are responsive to environments like hydrogels has given microrobots an additional degree-of-freedom. In the meantime, the two-photon polymerization (TPP) microscale 3D printing technique has enable fabrication process that cannot be achieved easily by traditional microfabrication techniques. In general, the goal of the research presented in this dissertation is to use both hydrogels and TPP to realize novel microrobots with multiple advanced functionalities, including adaptive locomotion and micromanipulation, and modular microrobots capable of changing end-effectors for different modes of micromanipulation to facilitate the development of the field. </p><p dir="ltr">This dissertation can be divided into four main parts: (i) a proof-of-concept study on adaptive helical microrobots with finite element analysis (FEA) and dynamic calculation, (ii) material calibrations and property testing, (iii) a helical adaptive multi-material microrobot (HAMMR), and (iv) a modular microrobot achieved by a responsive mating component. A environment-responsive hydrogel is adopted here to realize the adaptive locomotion for helical microrobot and the responsive mating component for the modular microrobot. All microrobots fabricated in this dissertation are achieved by the combination of TPP and traditional photolithography techniques. </p><p dir="ltr">In part (i), FEA is applied with classic parameters for a proof-of-concept study of helical microrobot made of the classic hydrogel upon the stimulation of temperature. At different temperature, the hydrogel is going to deform and therefore the microrobot. Based on the geometrical parameters predicted by FEA before and after stimulations, dynamic calculations are then applied to predict the change of swimming performance accordingly. In part (ii), material calibrations have been done in order to realize a homogeneous material for testing (for oil-immersion mode). However, due to the limitation of the custom-built testing system, a different approach (dip-in mode) is adopted and the material properties are successfully obtained. In part (iii), two generations of HAMMRs are investigated. The first generation of HAMMR is prepared by the oil-immersion mode which shows a record-breaking swimmering velocity with the capability of adaptive locomotion. The second generation is obtained by the dip-in mode which provides the opportunities for combining FEA, dynamic calculation, and experiment to realize a comprehensive studied for such microrobot. Moveover, advances have been made to the microrobot with a functional end-effector for micromanipulation tasks. In part (iv), a modular microrobot is proposed and realized by the introduction of a responsive mating component. The responsive mating component provides a locking mechanism between different modules of the microrobot. The microrobot is able to change its end-effector to perform different types of tasks. </p><p dir="ltr">By using TPP to pattern microscale hydrogel structures, microrobots are able to be implemented with advanced functional structures. The helical microrobots capable of adaptive locomotion and micromanipulation, and the modular microrobot that can switch end-effectors for different applications are advances toward the next generation of microrobots. Moreover, a standardized method is proposed for adaptive helical microrobots towards future biomedical applications. Both the proposed helical microrobot and the modular microrobot show great potential for future application and we believe the development of these microrobots will facilitate the development of the field of microrobot.</p>

<p>In this work, a mechanism is developed for an electric field to modulate the heat-release of a laminar flame. This mechanism is then used with a feedback controller to suppress thermoacoustic instabilities in a Rijke tube.</p>

<p>  </p> <p>Adhesives are becoming more widely used for applications that previously relied on mechanical methods to secure the interface of two materials due to their cost effectiveness, lower weight, and ease of use. Examples of these new adhesive spaces include functional adhesives for robotic or manufacturing applications, composite materials in automotives and aircrafts, and wearable medical devices. As adhesives continue to push into new spaces, new methods must be developed to control their adhesive properties. Furthermore, understanding how the adhesive properties of these materials change due to deformation is critical in order to select or design new adhesives for specific applications. </p> <p>In this work we develop a material with pressure tunable adhesion by utilizing surface patterning. A simple and scalable fabrication method, polymer thin film dewetting, is used to pattern the surface of a soft elastomer with stiff, microscopic, and axisymmetric asperities. Patterning of the surface with these asperities leads to pressure tunable adhesion where adhesion strength increases with increasing applied pressure. Additionally, it is shown that changes to the relationship between adhesion strength and applied pressure by altering the pattern geometry are investigated.</p> <p>The surface properties of amorphous elastomers have long been assumed to be independent of deformation. However, experimental studies within the last 15 years have shown this to be false for very soft solids and gels with moduli on the order of 10s-100s KPa when deformation of the material is below a critical length scale. The surface stress of these materials differs from the bulk and are dependent on the degree of deformation of the solid. Theoretical works have also shown this to be true for stiffer materials, however it is difficult to use the same experimental techniques to probe the surface stress of elastomers with moduli on the order of MPa. In this work, a new experimental technique is proposed to investigate the deformation dependent surface properties of elastomers. Additionally, this same technique allows us to probe the deformation-dependent adhesion properties of elastomers. We show that the shape of contact between a uniaxially stretched elastomer and rigid spherical probe provides insight into changes in surface stress. Furthermore, our results indicate that material composition, specifically filler composition and loading, affects the adhesion hysteresis of these elastomers. </p>