<p dir="ltr">Here we present two studies of different aspects of meteoritic impacts. The first study is about the behavior of ejecta plumes after a hypervelocity impact onto a body with an atmosphere. The second study looks at the effect vaporization has on meteoroids as they descend through Earth's atmosphere, specifically the effect permeability and meteor size have on the vaporization during their explosive fragmentation.</p><p dir="ltr">Atmospheres play an important role in ejecta deposition after an impact event. Many impact experiments and simulations neglect the effect of atmospheres. In the first study, we simulate ejecta plumes created by craters with transient diameters of 2 km and 20 km on Mars and Earth to show the difference atmospheric density and crater size have on the strength of the interaction. The interaction of ejecta with an atmosphere is explored in this study using a two-fluid hydrocode that simultaneously simulates ejecta and atmospheres as coupled, continuum fields to correctly capture the transfer of mass, energy, and momentum between the two. Here we study the effect of vaporization of plume material as well as the effect of the bow shock. We find that only the fastest ejecta is vaporized with a peak vaporized mass of 2.5x10⁵ kg, 3.5 s after the impact in our 2 km diameter Terrestrial crater. Terrestrial meteorites are preferentially formed from the fastest ejecta. However, that fastest ejecta is mostly vaporized in our simulations, so to form a Terrestrial meteorite there must be a sufficiently large impact for solid material to be ejected and not vaporize. Thus, we place a lower limit of 33 km on the size of crater needed to generate terrestrial meteorites, but the crater size needed could be substantially larger. The bow shocks in our simulations result in lofting of ejecta, especially vaporized material, in the wake of the impactor. We find that Mars' thin atmosphere slows the ejecta but does not significantly change the trajectory of the plume. Earth's atmosphere can stop and entrain ejecta particles to suspend heated material long after the majority of material has already been deposited, resulting in 4x10¹⁰ kg of material being suspended in the atmosphere 100 seconds after the impact for a 2 km diameter crater. For larger craters, we find that Earth's atmosphere has a more limited effect and ejecta more closely follows a ballistic trajectory.</p><p dir="ltr">The 1908 Tunguska bolide event and the 2013 Chelyabinsk bolide event underscore the potential damage posed by relatively small meteoroids as compared to the dinosaur-killing Chicxulub meteoroid. In this study, we model Tunguska- and Chelyabinsk-sized bolide events, extending the work of Tabetah and Melosh (2018) by exploring a larger parameter space and introducing the novel feature of material vaporization. Building upon their findings that the porosity and permeability of a meteoroid significantly influence fragmentation, we investigate additional factors such as meteoroid size, entry speed, and entry angle. Furthermore, we demonstrate that vaporization plays a crucial role, lowering the fragmentation height by extracting energy through latent heat. We find that a larger meteoroid size or higher entry speed increases the amount of vaporization that occurs while lowering the altitude of disruption of the meteoroid, and that a shallower entry angle decreases the amount of vaporization and increases the altitude of disruption. Our study not only refines the understanding of bolide events but also introduces a novel perspective with potential implications for planetary science and impact risk assessment.</p>

<p dir="ltr">Human-robotics teaming (HRT) has many highly impactful applications in industry, medical, rehabilitation, military, mixed reality, etc. High quality sensing technologies and communications are inevitable for the HRT development. Many commercial sensors, such as vision-based, audio-based and proximity sensors, are usually rigid and difficult for conformable and large-scale integration. Imperceptible soft sensing devices feasible for human/robot integration with high compliance are attractive for the HRT applications. In addition, ubiquitous sensing with good robustness, self-powered capability, high fidelity, and high SNR are desirable for future HRT.</p><p dir="ltr">This dissertation presents a comprehensive study of SITS theory, ink-based materials, scalable manufacturing methods to develop SITS devices for various applications, including spray coated SITS for human pulse analysis and robotic control, fabric smart glove for objects recognition, and plant triboelectric skin powered IoT sensing system. We develop the SITS theory and propose design strategies for high-performance SITS devices. We study the ink-based materials and scalable manufacturing methods for SITS. We also conduct materials modifications, device configuration and system integration to fabricate versatile SITS for different applications. The presented concepts and applications vast from human skin to plant skin, which shows great potentials to implement SITS technology for future HRT system.</p>

<p dir="ltr">This research presents a comprehensive study of a 3D Perovskite Solar Cell model using Finite Element Analysis (FEA) and Machine Learning (ML). The research aims (i) to understand how material properties impact solar cell’s performance by applying basic semiconductor physics principles (ii) to investigate how interfacial delamination affects the performance of Perovskite solar cells (iii) to determine the optimum thickness of different layers of the solar cell (iv) to determine the fatigue life cycle of Perovskite layer.</p>

<p dir="ltr">We present a model describing an impact jetting origin for the formation of chondrules, the mm– scale, igneous components of chondritic meteorites which originated during the first few million years of solar system history. The ubiquity of chondrules in both non-carbonaceous and carbonaceous chondrites suggests their formation persisted throughout the protoplanetary disk, but their formation mechanism is debated and largely unexplored in the outer disk.<b> </b>Using the iSALE2D shock physics code, we generate models of the process of impact jetting during mixed material (dunite and water ice) impacts that mimic accretionary impacts that form giant planet cores. We show that the process of impact jetting provides the conditions necessary to satisfy critical first-order constraints on chondrule characteristics (size, shape, thermal history). We then explore the implications of chondrule formation by impact jetting during the formation of giant planet cores by combining the original results with simulations of giant planet core accretion generated using a Lagrangian Integrator for Planetary Accretion and Dynamics (LIPAD) code.</p><p dir="ltr">The second closest Galilean satellite to Jupiter is Europa, an ocean world with an outer ice shell and subsurface water ocean encapsulating its rocky core. The surface of Europa is covered in double ridges. These features are defined by two topographic highs about 100 meters tall, with a central trough between them, which extend for hundreds of kilometers over the surface of the moon. Accurate models for the formation of features as prominent as double ridges will help to further constrain the interior structure and dynamics of the interior of the body. We use analytical and numerical finite element models to show that the incremental growth of an ice wedge within the ice shell can cause deformation matching the observed size and shape of observed double ridges on Europa. These models indicate that the total height and width of the ridges correspond to the depth of the wedge, so that deeper wedges create shorter and broader ridges. We consider different sources for the wedge material and ultimately argue in favor of local sources of liquid water within the ice shell.</p>

<p>Hyperphosphorylation of the microtubule-associated protein Tau is a major hallmark of Alzheimer’s disease (AD) and other tauopathies. Understanding the protein kinases that phosphorylate Tau is critical for the development of new drugs that target Tau phosphorylation. At present, the repertoire of the Tau kinases remains incomplete, and methods to uncover novel upstream protein kinases are still limited. Here, I apply our newly developed proteomic strategy, fluorescence complementation mass spectrometry (FCMS), to identify novel kinase candidates of Tau. By constructing Tau- and kinase-fluorescent fragment library, I detected 59 Tau-associated kinases, including 23 known kinases of Tau and 36 novel candidate kinases. In the validation phase using in vitro phosphorylation, 15 candidate kinases were successfully expressed and purified, and four candidate kinases, OXSR1, DAPK2, CSK, and ZAP70, displayed the ability to phosphorylate Tau. Furthermore, co-expression of these four kinases along with Tau increased the phosphorylation of Tau in human neuroglioma H4 cells. I demonstrate that FCMS is a powerful proteomic strategy to systematically identify potential kinases that can phosphorylate Tau in cells. Our discovery of new candidate kinases of Tau can present new opportunities for developing AD therapeutic strategies.</p>

<p dir="ltr">This study investigates the electrochemical behavior of molybdenum disulfide (MoS₂) when utilized as an anode material in Li-ion batteries, particularly focusing on the intriguing phenomenon of extra capacity observed beyond theoretical expectations and the unique discharge curve of the first cycle. Employing a robust suite of advanced characterization methods such as in situ and ex situ X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM), the research unravels the complex structural and chemical evolution of MoS₂ throughout its cycling process. A pivotal discovery of the research is the identification of a distinct lithium intercalation mechanism in MoS₂, which leads to the formation of reversible Li_xMoS₂. These phases play a crucial role in contributing to the extra capacity observed in the MoS₂ electrode. Additionally, density functional theory (DFT) calculations have been utilized to explore the potential for overlithiation within MoS₂, suggesting that Li₅MoS₂ could be the most energetically favorable phase during the lithiation-delithiation process. This study also explores the energetics of a Li-rich phase forming on the surface of Li₄MoS2, indicating that this configuration is energetically advantageous and could contribute further to the extra capacity. The incorporation of reduced graphene oxide (RGO) as a conductive additive in MoS₂ electrodes, demonstrating that RGO notably improves the electrochemical performance, rate capability, and durability of the electrodes. These findings are supported by experimental observations and are crucial for advancing the understanding of MoS₂ as a high-capacity anode material. The implications of this research are significant, offering a pathway to optimize the design and composition of electrode materials to exceed traditional performance and longevity limits in Li-ion batteries.</p>

<p>The production of insects for protein is projected to reach a market share of 1.33 billion USD, a rapid increase from the estimated 144 million USD share of 2019 market. The isolation of insect protein produces by-products, including chitin. Currently chitin is extracted from aquaculture by-products, such as shrimp and crab shells, and used to produce chitosan for various applications in the supplement and food industry. With the insect market expected to continue its growth, the feasibility of sourcing commercial chitin and chitosan from reared crickets’, and the application properties of its counterpart, chitosan, was investigated in this dissertation. In the first part of this dissertation, chitin from two commonly reared crickets in the Unites States, <i>Acheta domesticus</i> and <i>Gryllodes sigillatus</i>, was successfully extracted, purified, and identified as a commercially viable option for chitin and chitosan. Extensive crustacean chitin studies served as the foundation of purification steps, however durations were adjusted to account for intrinsic differences between insects and crustacean exoskeletons. Furthermore, cricket chitosan was prepared and optimized with varying degrees of deacetylation. As expected, cricket chitosan had lower molecular but did not have a detectable effect on the bioactive properties tested. All cricket chitosan produced had similar lipid binding capacity <i>in vitro</i>. Additionally, the microbial inhibition of cricket chitosan and commercial chitosan (~70% DDA) were not significantly different when evaluated against <i>L. innocua</i> and <i>E. coli</i>. High DDA cricket chitosan showed greatest bacterial inhibition as expected. In the second part of this dissertation, cricket derived chitosan showed similar and improved food packaging properties, when evaluated against commercial shrimp chitosan. microstructure analysis provided by scanning electron microscopy showed greater compaction and agglomeration of cricket chitosan films. The change in microstructure may be attributed to the increased complexity generally attributed to insect chitosan materials, a result of remaining melanin and protein in close association with insect exoskeleton chitosan. As a result, cricket films had similar or increased tensile strengths but decreased elongation percentages when compared to shrimp films. Water vapor permeability of cricket films was decreased due to tortuosity. Residual melanin likely played an important role in increasing cricket film surface hydrophobicity and providing enhanced light barrier properties. Overall, this dissertation successfully shows the potential of crickets as insect derived chitin and chitosan, and its effectiveness as a lipid binding and antibacterial agent, as well as its potential use in biobased food packaging. </p>

This research focuses on developing strategies for the optimal control of large-scale Combined Cooling, Heating and Power (CCHP) systems to meet electricity, heating, and cooling demands, and evaluating the cost savings potential associated with it. Optimal control of CCHP systems involves the determination of the mode of operation and set points to satisfy the specific energy requirements for each time period. It is very complex to effectively design optimal control strategies because of the stochastic behavior of energy loads and fuel prices, varying component designs and operational limitations, startup and shutdown events and many more. Also, for large-scale systems, the problem involves a large number of decision variables, both discrete and continuous, and numerous constraints along with the nonlinear performance characteristic curves of equipment. In general, the CCHP energy dispatch problem is intrinsically difficult to solve because of the non-convex, non-differentiable, multimodal and discontinuous nature of the optimization problem along with strong coupling to multiple energy components. <div><br></div><div>This work presents a solution methodology for optimizing the operation of a campus CCHP system using a detailed network energy flow model solved by a hybrid approach combining mixed-integer linear programming (MILP) and nonlinear programming (NLP) optimization techniques. In the first step, MILP optimization is applied to a plant model that includes linear models for all components and a penalty for turning on or off the boilers and steam chillers. The MILP step determines which components need to be turned on and their respective load needed to meet the campus energy demand for the chosen time period (short, medium or long term) with one-hour resolution. Based on the solution from MILP solver as a starting point, the NLP optimization determines the actual hourly state of operation of selected components based on their nonlinear performance characteristics. The optimal energy dispatch algorithm provides operational signals associated with resource allocation ensuring that the systems meet campus electricity, heating, and cooling demands. The chief benefits of this formulation are its ability to determine the optimal mix of equipment with on/off capabilities and penalties for startup and shutdown, consideration of cost from all auxiliary equipment and its applicability to large-scale energy systems with multiple heating, cooling and power generation units resulting in improved performance. </div><div><br></div><div>The case-study considered in this research work is the Wade Power Plant and the Northwest Chiller Plant (NWCP) located at the main campus of Purdue University in West Lafayette, Indiana, USA. The electricity, steam, and chilled water are produced through a CCHP system to meet the campus electricity, heating and cooling demands. The hybrid approach is validated with the plant measurements and then used with the assumption of perfect load forecasts to evaluate the economic benefits of optimal control subjected to different operational conditions and fuel prices. Example cost optimizations were performed for a 24-hour period with known cooling, heating, and electricity demand of Purdue’s main campus, and based on actual real-time prices (RTP) for purchasing electricity from utility. Three optimization cases were considered for analysis: MILP [no on/off switch penalty (SP)]; MILP [including on/off switch penalty (SP)] and NLP optimization. Around 3.5% cost savings is achievable with both MILP optimization cases while almost 10.7% cost savings is achieved using the hybrid MILP-NLP approach compared to the current plant operation. For the selected components from MILP optimization, NLP balances the equipment performance to operate at the state point where its efficiency is maximum while still meeting the demand. Using this hybrid approach, a high-quality global solution is determined when the linear model is feasible while still taking into account the nonlinear nature of the problem. </div><div><br></div><div>Simulations were extended for different seasons to examine the sensitivity of the optimization results to differences in electric, heating and cooling demand. All the optimization results suggest there are opportunities for potential cost savings across all seasons compared to the current operation of the power plant. For a large CCHP plant, this could mean significant savings for a year. The impact of choosing different time range is studied for MILP optimization because any changes in MILP outputs impact the solutions of NLP optimization. Sensitivity analysis of the optimized results to the cost of purchased electricity and natural gas were performed to illustrate the operational switch between steam and electric driven components, generation and purchasing of electricity, and usage of coal and natural gas boilers that occurs for optimal operation. Finally, a modular, generalizable, easy-to-configure optimization framework for the cost-optimal control of large-scale combined cooling, heating and power systems is developed and evaluated.</div>

<p>The purpose of this research was to determine what components of a complex centrifugal  compression system inlet needed to be modelled to accurately predict the swirl and total pressure  distortions at the compressor face. Two computational models were developed. A full-fidelity case  where all the inlet geometry was modelled and a reduced model where a small portion of the inlet  was considered. Both the numerical cases were compared with experimental data from a research  compressor rig developed by Honeywell Aerospace. The test apparatus was designed with a  modular inlet system to develop swirl distortion patterns. The modular inlet system utilized  transposable baffles within the radial-to-axial section of the inlet and blockage plates of varying  sizes and geometries at the inlet to this section.  Discerning the dominant inlet component that dictates distortion behavior at the compressor  face would allow the reduced modelling of inlet components for compression systems and would  allow coupling with more tortuous systems. Furthermore, it would reduce the design iteration and  simulation time of the inlet systems. Several investigations utilizing a reduced model only  considering a radial-to-axial inlet are available in literature, but no comprehensive justification has  been presented as to the impact this has on the distortion behavior.   Experimental surveys of flow conditions just upstream of the inducer of the centrifugal  compressor were conducted at several operating conditions. The highest and lowest mass flow  rates of these operating points were simulated using ANSYS CFX 2020R1 for both the  computational models. Multiple inlet configurations were simulated to test the robustness of the  reduced model in comparison to the full fidelity. The numerical simulations highlighted  shortcomings of the instrumentation used to characterize the experimental flow field at the inducer,  particularly with respect to total pressure distortion. Furthermore, transient pressure data were  measured in experiment and indicated unsteady fluctuations in the inlet that would not be captured  by steady computational fluid dynamic simulations. These data matched locations of disagreement  with swirl distortion behavior at high mass flow rates. This suggested that transient vortex  movement occured at the aerodynamic interface plane in certain configurations.   The total pressure distortion metrics between the two models were remarkably comparable.  Furthermore, the simplified model accurately predicted the mixing losses associated with the  blockage plates at the inlet to the radial-to-axial inlet using a simple inlet extension. Swirl  18  distortion was dictated by the radial-to-axial inlet. The reduced model data trends were comparable  with experiment for both the baffle and blocker plate configurations. The swirl intensities for all  configurations were comparable between the two models. The reduced model swirl directivity  trends matched those of experiment. The most notable deviations between the full-fidelity model  and the reduced model were observed with swirl directivity numerics. </p>

<div> <p> Aircraft engines require lightweight efficient thermal management devices to improve engine performance at high pressure ratios. Acoustic streaming can provide a viable, lightweight solution to improve the heat exchanger capacity with a reduced drag penalty within engine heat exchangers. This project develops a test section that will experimentally characterize the effect of acoustic streaming on the unsteady heat flux and shear stress within a narrow channel. This is accomplished by careful selection of measurement techniques to monitor the steady and unsteady properties of the flow and iteratively designing the test section with CFD support to converge to an optimal test model. Using CFD support to revise each iteration reduces the experimental cost of developing an effective geometry. </p> <p> Pressure taps and K-type thermocouples are used to monitor the total inlet pressure and temperature as well as the wall surface pressure and temperature. Optical shear stress sensors are selected to monitor the unsteady wall shear stress. A thin film sensor array is designed for high frequency wall temperature measurements which serve the boundary condition for a 1-D heat flux analysis to determine the unsteady heat flux through the wall. The test model consists of two hollow Teflon airfoils that create a narrow channel within a larger flow area. The airfoils create three flow paths within the wind tunnel test section and the area ratio between the measured flow and the bypass flow controls the Mach number of within the measured flow channel. The acoustic waves drive acoustic streaming and are generated by a Rossiter Cavity with L/D =2 which produces pressure oscillations with dominant frequency of 8 kHz in a Mach 0.8 flow. </p> <p> The test geometry successfully achieves <a>Mach 0.8 flow and the 8 kHz signal </a><a href="https://purdue0-my.sharepoint.com/personal/mbutzen_purdue_edu/Documents/MS Thesis/Thesis Living Document.docx#_msocom_1">[BMJW1]</a> from the Rossiter cavity. The successful commissioning sets the stage for future experiments to determine the potential of acoustic streaming as a low weight modification to improve compact heat exchangers. </p> </div> <div><div><div><br> </div> </div> </div>