Advisor: Dr. Francisca Oboh-Ikuenobe
Date & Time: Monday December 5th, 2022 at 2:00 PM
Abstract: The unique alignment of the Decaturville, Crooked Creek, Weaubleau geological structures in central Missouri, three of seven such structures along the 38th parallel in Illinois, Missouri and Kansas, has puzzled geoscientists for decades. Two case studies integrating palynology (palynomorphs and particulate organic matter/palynofacies) with radiometric dating of impact spherules provided the opportunity to evaluate these enigmatic structures in order to constrain the age and relationship of the structures, and also infer their paleoenvironmental conditions. Novel damages that are unique to meteorite impact were documented in the palynomorphs in all the three structures. Early Ordovician acritarchs with melted processes correlate with 40Ar-39Ar stepwise heating age of impact spherules from the Crooked Creek structure, and this age is coeval with a large clustering event in the Ordovician that was responsible for other craters in North America and globally. The presence of melted acritarchs, other palynomorphs, and particulate organic matter of mixed ages and environments reflect the dynamic and catastrophic effects of meteorite impact on the sedimentary environments and stratigraphy.
A third case study was conducted on the palynomorphs, palynofacies and foraminiferal contents in 43 samples from four wells in the Orange Basin located offshore western South Africa. The aim was to constrain paleoenvironmental conditions and evaluate the hydrocarbon potential in an understudied area of this offshore frontier basin. Key biostratigraphic and palynofacies information indicate a Cenomanian age for the studied interval, an inner to middle shelf setting, and an arid hinterland at the time of deposition. This case study also suggested that the sediments were characterized primarily by gas-prone type III kerogen and some oil-prone type II kerogen.
Advisor: Dr. Kelly Homan
Date & Time: Wednesday December 7, 2022 at 10:00 AM
Location: Toomey Hall 144
Abstract: Advent of additive manufacturing and various other fabrication techniques has provided freedom for researchers, to forge complex structures in-order to enhance the scalar transportation of a fluid. Primarily due to implementation of metal matrix foams and organized lattice structures. The widely existing literature till date is only focused on wakes produced by basic structures such as cylinder, sphere, flat plate and 2D meshes. Recently, several researchers are focusing on the flow perturbation provided by complex matrix structures as a whole. We try to address few key distinguished flow characteristics offered by a node/junction, which are profusely found in any complex foam structures. In order to keep our analysis simple, we have isolated a three dimensional (3D) junction of an orthogonal structured lattice and call it as Unit-cell. An isolated unit-cell is tested in a wind tunnel to discover a remarkable wake phenomenon.
Upon gaining knowledge of a wake behind single unit-cell, we turned to expand our outreach by experimenting with the wake behind tandem unit-cells and three dimensional (3D) meshes. The box or 3D meshes could be considered as a true representation of a complex organized structure with a unit thickness along the flow.Wake, investigation by standard experimental techniques using Hot wire anemometry (HWA) is carried out in a sub-sonic wind tunnel, which facilitate us to probe numerous point locations to better understand the wake on a whole. Lastly, we introduce our initiative in setting up CFD simulation to address few unknowns which remain unanswered by experimentation techniques.
Advisor: Dr. David Borrok
Date & Time: Wednesday December 7, 2022 at 10:00 AM
Abstract: Hydrofracturing (fracking), a common practice in the Petroleum Industry to induce or
improve fluid flow in tight formations, creates chemical disequilibrium that further alters the
porosity and permeability of host rocks and results in the production of saline and contaminated
produced waters (PW). The Tuscaloosa Marine Shale (TMS) is an active oilfield in Mississippi
and Louisiana, with wells producing for between two to five years. In that time, 15 to 110% of
the fracking water volume used has returned as PW. These PWs are Na-Ca-Mg-K-Cl brines with
mean concentrations of approximately 16% Total Dissolved Solids (TDS) and circumneutral pH.
Analysis of the PW composition and comparison to evaporated seawater suggests the PWs result
from a 20 to 80% dilution of formation waters (relict brines of the Louann Salt) by fracking
fluid. Trace element concentrations generally show moderate to strong correlations with overall
salinity, except Cu and V, which show a moderate correlation with the volume of oil produced,
suggesting they are affiliated with dissolved organic phases. When compared to adjacent
formations, lower concentrations of Pb and Zn transition metals suggest the presence of higher
amounts of H 2 S in the TMS, limiting the solubility of sulfide phases.
Fracking is also used in wastewater disposal and enhanced geothermal system (EGS)
energy production, where chemical variations of injection fluid affect the disequilibrium
reactions in the host rocks. To improve our understanding of fluid-shale interactions over a broad
range of fluid chemistries, we performed 56-day batch reaction experiments between shales from
the TMS and solutions with combinations of the following initial values; (1) pH of 2, 4, or 6, (2)
salinities of <0.1%, 3.2%, or 12% TDS, and (3) NaCl or Na-Ca-Mg-K-Cl compositions. Findings
show that while the timing and extent of reactions varied with the initial fluid chemistry,
resulting solutions converged to similar end chemistries. On one end, solutions with salinities
<0.1% and an initial pH of 2 resulted in silicate weathering, sulfide oxidation, and carbonate
dissolution, which increased the rock’s porosity. However, this was followed by the precipitation
of clays, iron (hydr-)oxides, and sulfate minerals that either reduces rock porosity or induces pipe
scaling. On the other hand, solutions with 12% TDS of Na-Ca-Mg-K-Cl compositions with an
initial pH of 6 resulted in silicate weathering and sulfide oxidation but little to no carbonate
dissolution, limiting chemical alterations to porosity. These results indicate that wastewater
disposed or reused as fracking fluid into parent formations and the cycling of water-based EGS
fluids should not have a significant secondary impact on host formation porosities.
Advisor: Dr. Marek Locmelis
Date & Time: Thursday December 8, 2022 at 9:00 AM
Location: McNutt Hall 204
Abstract: Iron-oxide-copper-gold (IOCG) deposits, despite their known potential for cobalt and copper in an increasingly metal dependent world, are exceptionally poorly understood mineral systems. For example, it is not well understood why copper- and cobalt-rich IOCG deposits often occur in the same terrane as Fe ore deposits that are notably copper and cobalt-poor, such as Iron Oxide Apatite (IOA) deposits. To help better understand the formation of variably copper and cobalt mineralized Fe deposits in Southeast Missouri, USA, this PhD thesis examines the genesis of the copper-cobalt-poor Kratz Spring IOA deposits and compares the findings to the copper-cobalt-rich Boss Central Dome IOCG deposit. This study presents the first constraints on formation conditions and fluid sources in the Kratz Spring and Boss Central Dome deposits using drill core studies, petrographic observations, ore microscopy, mineral chemistry, and iron isotope analysis of oxide minerals. The data show that the Kratz Spring deposit is primarily composed of magnetite with lesser hematite and can be sub-divided into two deposits: (i) a northern ore body with magnetite formation temperatures of 650-850°C and (ii) a southern ore body with magnetite formation temperatures of 350-500°C. Trace element and Fe isotopic compositions of oxide minerals suggest that he two sub-deposits at Kratz Spring were formed from different fluid sources, i.e., the southern sub-deposit has data consistent with a juvenile magmatically exsolved fluid, while the northern deposit’s data suggest significant input and dilution from meteoric or sedimentary fluids. The Boss Central Dome deposit’s iron oxide ore minerology is similar to Kratz Spring, but it is also notaby rich in copper and cobalt sulfides. Magnetite analysis suggest that the magnetite ore in the Boss Central Dome deposit formed from a juvenile fluid with a temperature of 300-600°C. The ore-forming conditions suggest that the Kratz Spring South IOA deposit is more similar to the distant Boss Central Dome IOCG deposit than to the much closer Kratz Spring North deposit. The observations of this study support linking Missouri's IOA and IOCG deposits to a single crustal-scale magmatic-hydrothermal system.
Advisor: Dr. Donghyun Kim
Date & Time: Friday December 9, 2022 at 5:00 PM
Location: Hypoint, 4000 Enterprise Drive
Abstract: Due to the wide-band spectrum of digital signals, a variety of noise generators, including microprocessors, liquid crystal displays, digital microphones, high-speed traces, and double-data-rate memory modules, are found in consumer electronics products. Noise generated by digital circuits can couple to the antennas and degrade their sensitivity. Additionally, it also couples to metallic housings or heatsinks and produces a significant amount of emission.
In this research, a geometry-aware methodology is proposed to analyze the coupling and radiation mechanism in electronic devices.
To investigate the coupling between the distributive geometries in the radio frequency interference (RFI) problem, a mesh-dependent partition-based coupling mechanism analysis method is provided based on the retarded partial element equivalent circuit (rPEEC) model. The proposed method can quantify the capacitive and inductive coupling between the layout partitions and offers a clear physical understanding of the coupling study.
The dipole moment is a popular equivalent noise source for digital circuits. The characteristic mode theory (CMT) is used as a systematic method to study the interaction between the equivalent noise source and the metallic housings. An analytic modal-based equation is used to predict the emissions. Mitigation methodologies, such as component placement and grounding post design, are also discussed based on the modal analysis results.
The transfer function method is commonly used for RFI problem analysis and mitigation. In this work, using the CMT, a modal-based analysis is provided to calculate the transfer function between the aggressor and the antenna port. The interference can be mitigated by component placement and changes in the antenna designs without compromising the antenna performance.