Mines Repository (Colorado School of Mines)
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Hydrologic model diagnostics using multiple observation datasets: a case study in the Upper Colorado River Basin
No full textIncludes bibliographical references.2025 Spring.Hydrologic models are traditionally calibrated to streamflow only, and the increasing availability of in situ and satellite-based observations provides numerous opportunities to constrain model outputs and improve process representation. However, as new observation data emerges, it is often unclear whether calibration with the additional data would inform or disinform streamflow prediction. In this study, we carry out multi-observational diagnostics with the pywatershed hydrologic model in four headwater catchments in the Upper Colorado River Basin. We use seven different calibration data products that pertain to discharge, snow water equivalent, snow-covered area, soil moisture, and evapotranspiration. These include both in situ and satellite-based observations. Informative model parameters are identified using the Morris screening method across all data sets, followed by a qualitative assessment of parameter estimation and streamflow performance using a Latin Hypercube Sample Monte-Carlo filtering approach. Results show that an increased number of informative parameters are determined through the screening process with the use of observation data representing terms beyond streamflow alone, and that forcing corrections and rain-snow partitioning parameters are particularly impactful to the model fit to observations. Multi-objective Monte Carlo filtering reduces the number of viable parameter sets, and the estimated parameter values depend strongly on the observation data. Evapotranspiration is informative to streamflow prediction across all catchments, but snow and soil moisture datasets are only informative in some catchments. These results provide insight into the value of alternative observation data for streamflow prediction and highlight the need for model diagnostics as new observations become available. Understanding the potential benefits of alternative observation data has implications for observational priorities, model development, and hydrologic forecasting
Coordinated control of distributed energy resources in power distribution system
No full textIncludes bibliographical references.2025 Spring.Recent advancements in photovoltaic (PV) and battery technologies, along with significant improvements in the efficiency of power electronic converters, have led to a rapid increase in the penetration of rooftop PV systems and electric vehicles (EVs) within distribution networks. While the integration of these technologies offers substantial economic and environmental benefits and supports the transition toward a more sustainable energy future, it also introduces new operational challenges for power systems. These challenges may include voltage fluctuations, increased system losses, and occurrences of overvoltage or undervoltage, particularly under high PV and EV adoption levels.
Traditionally, voltage and reactive power regulation in distribution systems has been managed through Voltage and Var Control (VVC) schemes using equipment such as substation on-load tap changers (OLTCs), voltage regulators, and shunt capacitors. However, with increasing PV and EV penetration, it becomes essential to consider these distributed energy resources in coordination with conventional control devices. This shift necessitates the development of a unified framework for Voltage, Var, and Watt Control (VVWC) to ensure reliable and efficient grid operation.
The primary objective of this study is to propose a comprehensive and realistic solution for the coordinated control of PV and EV resources in unbalanced power distribution systems, while considering sustainability and energy justice objectives. To achieve this, a mixed-integer nonlinear multi-objective optimization model is developed, employing a Chebyshev goal programming approach to ensure Pareto-optimal solutions. The model incorporates multiple objectives, including minimizing PV active power curtailment, reducing system losses, flattening the voltage profile, and minimizing unserved demand weighted based on social vulnerability. The formulation accounts for the inherent asymmetries and phase imbalances in distribution systems. To further enhance the study, a seasonal hosting capacity analysis was conducted using correlated hourly sampling, capturing system behavior across different seasons.
The proposed VVWC framework is validated through simulations on a modified version of the IEEE 123-bus test feeder, demonstrating its effectiveness in supporting high PV and EV penetration levels while maintaining grid stability and operational efficiency. Most importantly, the study confirms that only through coordinated control strategies can power systems achieve higher integration of distributed energy resources
f-element coordination behavior of minor actinide chelators and impacts of ionizing radiation on actinide systems in aqueous solutions
No full textIncludes bibliographical references.2025 Spring.Within this work, the structural trends and spectroscopy characteristics of the hydrophilic f-element chelator tetramethyl diglycolamide (TMDGA) complexes with 4f and 5f elements were studied comprehensively to identify trends and systematic behaviors across the lanthanide (Ln) series and compared to differences and trends observed across the actinide (An) series. Additionally, this in-depth structural study attempts to bridge structural analysis with the field of radiation chemistry, to further develop an understanding of radiation interactions as it pertains to metal ion complexation of chelating ligands.
Crystals of TMDGA metal ion complexes across the lanthanides display consistent tris Ln TMDGA cationic metal centers taking distorted spherical capped square antiprism geometries across the lanthanides and actinides. Early Ln (Ln = La – Sm) TMDGA complexes took the formula, [Ln(TMDGA)3][Ln(NO3)6], featuring a hexanitrato anionic environment. A change in solvent for the crystallization reactions was found to be necessary after samarium in order to produce crystals suitable for single-crystal X-ray diffraction. The mid to late lanthanides (Ln = Eu – Yb) displayed a divergence from the anionic environment, taking multiple coordination environments with the generic formula, [Ln(TMDGA)3][Ln(NO3)5(H2O)]1−x[Ln(NO3)4(H2O)2]x(NO3)1+x. These structures displayed a trend across the series increasingly favoring a less sterically crowded coordination environment around the anionic metal ion complex, which is displayed through the decreasing favorability of nitrate coordination. The Lu structure displayed another coordination change, displaying a further favorability towards decreasing nitrate coordination, taking the formula, [Lu(TMDGA)3]2[Lu(NO3)4(H2O)2]0.75[Lu(NO3)5(H2O)]1.25(NO3)2.75·H2O. Significant asymmetric bonding in the lutetium system indicated that the steric crowding around the metal was almost extreme enough to cause a decrease in coordination number around the lutetium metal ion from 10- to 9-coordinate.
Early transuranic actinides (An = Pu, Am) displayed isostructural behavior to that of the early lanthanides, taking the formula [An(TMDGA)3][An(NO3)6]. Coordination of the plutonium complex in the tetravalent state afforded a homoleptic plutonium complex. A significant drop in metal–oxygen bond lengths, indicative of an increase in oxidation state were observed, as well as a change in the local symmetry around the plutonium TMDGA metal ion complex. However, although the changing reaction conditions observed in the lanthanides helped to inform the necessary reaction conditions for the mid-actinide reactions, berkelium and californium displayed deviations from the structural patterns observed in the lanthanides. Berkelium, taking the formula [Bk(TMDGA)3]2(NO3)6, displayed a notable deviation in anionic behavior in these TMDGA systems, as the nitrate ion are no longer coordinating with a metal center, and instead, are situated around the outer sphere of the Bk(TMDGA)3 complex. Similarly, the nitrate anions in the californium complex did not display any coordination with a californium metal ion, instead, the four nitrate ions orienting themselves around an ammonium via hydrogen bonding interactions.
Crystallization reactions were conducted with TMDGA using tetraphenylborate as the counter ion, taking the formula [M(TMDGA)3](BPh4)3 (M = Nd, Eu, Am, Bk, Cf). Although the coordination habits in the metal ion TMDGA complex were similar, geometry calculations revealed some subtle differences in the coordination environment. The close proximity of the large tetraphenylborate counterions to the coordinated TMDGA ligands imposed bending and torsion of the ligand as it was complexed. This bending resulted in a decrease in symmetry from C4v to Cs and a notable increase in complexity of the absorption spectra.
Through the development of this work, it was unveiled that there was a serious lack in structural analysis of a popular aqueous phase chelating ligand, triethylenediaminepentaacetic acid (DTPA). Successful synthesis of neodymium and americium DTPA, holding the formula [C(NH2)3]4[M(DTPA)]2, consisted of two americium DTPA complexes, connected together via a carboxylic acid group to afford a bimetallic complex. Solvent voids consisting of water molecules were modeled between the bimetallic complexes. When placed under pressure, the americium DTPA crystal displayed little response to pressure, atypical of most actinide coordination complexes, especially in those with softer electron donating atoms such as nitrogen in DTPA. Contractions in the metal–nitrogen bond lengths indicated a slight preference for the actinide complex over the neodymium complex.
The radiation kinetics of berkelium and californium with common nitric acid reactive radical species (eaq−, H•, NO3•−, and •OH) were investigated to study their readiness to undergo various redox reactions within nuclear reprocessing technologies. Despite these reactive radiolysis species not holding sufficient redox potentials, berkelium and californium readily react to transiently undergo these oxidation state changes. In all cases, berkelium displayed increased reactivity over that to the equivalent californium reaction. Additional measurements with californium and the dichloride radical anion (Cl2•−) and the sulfate radical anion (SO4•−) were undertaken to explore the reactivity of potential radical anions present in some lesser used separation and purification processes. The dichloride radical anion was found to have little to no reactivity, showing that this reaction holds negligible impact on processes in the presence of chloride. The SO4•−, however, displayed significant reactivity over that of any of the aforementioned oxidizing radical species and faster than its reaction between that of other trivalent actinides, indicating that the sulfate radical anion displays promise for the selective oxidation of californium
Argyle Silver Mining Company
No full textMine report no. 1750.Typescript (copy).Includes maps, illustrations, and five letters of correspondence.Condensed report: Argyle Silver Mining Company -- Correspondence from Frank E. Shepard to J.M. McClave, dated February 19, 1924 -- Correspondence from M.G. Henry to Clarence E. Shepard, dated January 12, 1924 -- Correspondence to M.G. Henry dated February 25, 1924 -- Correspondence to Snow Creek Mining Co. from Mines Securities Co. manager, E.T. Hiatt, dated December 28, 1923
Lisbon group, Pennington County, South Dakota
No full textMine report no. 1892.Typescript (carbon copy).Title supplied by cataloger.Includes one map of Lisbon group of claims
Anode catalyst layer design for anion exchange membrane water electrolyzers
No full textIncludes bibliographical references.2025 Spring.Hydrogen production through water electrolysis enables the efficient conversion of low-cost, renewable electrons into stored chemical energy, addressing the curtailment of variable renewable energy sources (VREs) such as wind and solar while offering a promising long-term energy storage solution. This process provides green alternatives for carbon-intensive sectors, including transportation; steel, cement, ammonia production; and chemical synthesis, thereby facilitating the transition from fossil fuels to VREs. However, barriers to the widespread adoption of water electrolysis include the high costs and limited availability of materials in state-of-the-art Proton Exchange Membrane Water Electrolyzers (PEMWEs), as well as the low efficiency and intermittent operation limitations of commercial Liquid Alkaline Water Electrolyzers (LAWEs). Anion Exchange Membrane Water Electrolyzers (AEMWEs) present a promising solution by enabling high-current-density, intermittent operation with the use of earth-abundant, non-platinum group metal (PGM) materials, offering a sustainable alternative for green hydrogen production. This thesis addresses key challenges in advancing AEMWE technology by combining fundamental and applied catalysis techniques. First, various candidates for the alkaline oxygen evolution reaction (OER) are screened, and different methods for normalizing activity are explored. The thesis then investigates the evolution of catalyst materials under AEMWE operating conditions (e.g., high voltage and alkaline pH) to understand how these materials can be activated for optimal performance. These insights are then applied at the device level, where the integration of catalysts with the ionomer phase is studied in terms of their interactions, integration, and degradation. Finally, the origins of catalyst layer resistance are examined and a novel method for voltage breakdown analysis in AEMWEs is proposed
Nickel: the nickel producing localities
No full textMine report no. 2019.Typescript (copy).Includes two versions of report; one with handwritten annotations
Wick's Gulch placer claims, Sierra County, New Mexico
No full textMine report no. 1857.Typescript (carbon copy).Title supplied by cataloger.Includes one topographic map dated 1961
Engineering quantum states and non-equilibrium quantum matter in open quantum many-body systems
No full textIncludes bibliographical references.2025 Spring.Open quantum systems are quantum systems that interact with an environment whose state is not known and whose interactions can not be controlled or monitored easily. Even though open quantum systems are ubiquitous in nature, they are less understood than their closed counterparts. Improved understanding of open quantum systems could help elucidate the sources of decoherence in quantum computers and simulators. Moreover, if the dissipation on an open quantum system can be controlled and engineered, one may create new phases of quantum matter or novel many-body entangled state that are hard to prepare for a closed quantum system. In this thesis, I describe my research efforts to understand and engineer open quantum many-body systems with a particular focus on quantum simulators using trapped atomic ions.
In Chapter 2, I propose an experiment for trapped-ion quantum simulators that could observe a novel driven-dissipative phase transition in a long-range transverse field Ising model (TFIM) for the first time. I present two experimentally practical protocols to engineer the required dissipation on the Ising model. One scheme simulates continuous dissipation by continuous optical pumping with carefully chosen laser configurations. The other scheme involves a periodic, probabilistic, measurement procedure that creates effective dissipation in a Floquet manner. In this proposed experiment, the competition between the drive and the dissipation makes the steady state of the system non-equilibrium, leading to novel features that cannot be observed in thermal equilibrium. These features can be captured by measuring two-time correlation functions in the steady state, and I provide a practical experimental method to measure these two-time correlations. With these two-time correlations, I show that the non-equilibrium features of the model can be observed for small or intermediate system sizes, making the results highly relevant for near-future experiments.
In Chapter 3, I generalize the above-mentioned idea of engineering dissipation via Floquet dynamics to realize more complicated open quantum many-body models. I show that Floquet dissipative maps can generate a large class of Lindblad master equations. Moreover, they can be used to simulate novel types of dissipation that are not easily accessible through existing methods, such as correlated dissipation or asymmetric/chiral dissipative transport processes. Through numerical simulations, I also find that the Floquet dissipation creates qualitatively similar steady states compared to continuous dissipation even with a moderately large period, making experimental realizations within reach.
In Chapter 4, I discuss a collaborative work with an ion-trap experimental group where I modeled an experimental quantum simulator as an open quantum many-body system. In the experiment, my collaborators worked to prepare a continuous symmetry breaking phase of a long-range transverse field Ising model. They find that their prepared state has the expected long-range correlations from the continuous symmetry breaking, but the observed correlations are much smaller than those predicted from my theoretical simulations using the experimental parameters if no decoherence is included. I then developed a microscopic model to include the most likely decoherence processes in the experiment and fit the decoherence rates from experimental data. I find that my model well reproduces the experimental measurement data, and I attribute the remaining difference between the theory and experiment to error sources that cannot be modeled with a standard Lindblad master equation, as well as a sub-optimal ramping function used in the preparation of the ground state.
In Chapter 5, I propose to modify the experimental setup in the previous chapter to prepare the ground-state of a spin-1 anti-ferromagnetic long-range Heisenberg model that exhibit a symmetry protected topological order. This ground state is much more challenging to prepare. I explore how to best optimize the ramping function used to prepare the state, applying a method based on adiabatic state preparation and a second, more sophisticated method based on gradient descent. I also model the effects of an expected shot-to-shot magnetic field noise that could be detrimental in our efforts to prepare the ground-state. I explore two distinct methods to mitigate this field noise: either by applying a large transverse field or applying spin-echo pulses. I show that spin-echo pulses can improve state fidelity, but unwanted resonance effects generated by the pulses could result in poor state fidelity. Such negative effects can be suppressed by a careful choice of the number of echo pulses applied. While I find that a large magnetic field appears to be a simpler yet effective way to mitigate this noise, this large field could introduce additional errors due to unwanted spin-phonon entanglement. How to suppress such phonon induced errors in the presence of a large field remains an important open question in trapped-ion quantum simulators.
In Chapter 6, I summarize my PhD research and point out several future direction my research can lead to. These include further collaboration with trapped-ion experimentalists to implement the aforementioned proposals, efforts to model correlated dissipation and shot-to-shot fluctuations in ion-trap quantum simulators, and protocols to simulate non-Hermitian many-body Hamiltonians using measurement feedback and post-selection
Report on Omega mine
No full textMine report no. 1893.Typescript (carbon copy).Includes one map entitled: Map of the Omega group, Clark, Gold Dust, Flying Dutchman group, and Fort Meade placer