Browsing by Subject "Generation"
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Item Characterization of a Stochastic Procedure for the Generation and Transport of Fission Fragments within Nuclear Fuels(2013-04-15) Hackemack, Michael WayneWith the ever-increasing demands of the nuclear power community to extend fuel cycles and overall core-lifetimes in a safe and economic manner, it is becoming more necessary to extend the working knowledge of nuclear fuel performance. From the atomistic to the macroscopic level, great morphological changes occur within the fuel over its lifetime. The main initial damaging events produced by fuel recoils from fast neutrons and fission fragment spiking leads to the onset of grain growths and fuel restructuring. Therefore, it is desirable to have a more detailed understanding of the initial events leading to fuel morphology changes at the atomistic level. However, this is difficult to achieve with the fission fragments due to the wide variability of their species (charge, mass, and energy) and the large averaging of their relative yields in the nuclear data files. This work is our first iteration at developing a general methodology to characterize a procedure, based on Monte Carlo principles, for generating individual fission event result channels and analyzing their specific response in the fuel. We utilized the nuclear reaction simulation tool, TALYS, to generate energy-dependent fission fragment yield distributions for different fissile/fissionable isotopes. These distributions can then be used in conjunction with fuel isotopics and a neutron energy spectrum to generate a fission-reaction-rate-averaged distribution of the fission fragment yields. We then used Monte Carlo sampling to generate the result channels from individual fission events, using the Q-value of the prompt fission system to either accept or reject. The simulation tool: Transport of Ions in Matter (TRIM) was used to characterize the general response of the fission fragment species within Uranium Dioxide (UO2), including the range, energy loss, displacements, recoils, etc. These responses were then correlated which allowed for the quick calculation of the response of the individual fission fragment species generated from the Monte Carlo sampling. As an example of this strategy, we calculated the response on a PWR fuel pin where MCNP was used to generate a high-fidelity neutron energy spectrum.Item Generation capacity expansion planning using screening curves method(2013-05) Zhang, Tong, active 2013; Baldick, RossGeneration capacity expansion planning has been evolving in rencent decades. First, the long-term planning procedure is taking more detailed considerations of short-term operation impacts. Second, as more renewable resources being integrated into the grid, a new strategy of dealing with the non-dispatchable renewable energy should be developed, with more ancillary services needing to be procured from thermal units. These trends are expected to continue. This thesis describes a methodology in generation capacity expansion planning. The screening curves method can be used to estimate optimal generation mix for a target year. This thesis first introduces three screening curves methods, which are classified based on their ability to deal with detailed shortterm operational issues. It then includes ancillary service and wind integration impacts. Finally, it presents a case study of a projected ERCOT 2030 system.Item Generation, stability, and transport of nanoparticle-stabilized oil-in-water emulsions in porous media(2014-05) Gabel, Scott Thomas; Bryant, Steven L.; Huh, ChunThe ability of nanoparticles to stabilize oil/water emulsions provides many interesting opportunities for the petroleum industry. Emulsions can be used as a displacing fluid for enhanced oil recovery to improve sweep efficiencies. Emulsions can be used to improve conformance control by effectively blocking thief zones in reservoirs with a high degree of heterogeneity. As shown in this thesis emulsions can be used to deliver fluids that contact and mobilize residual oil. It is imperative to understand emulsion behavior in porous media for design purposes in enhanced or improved oil recovery processes involving emulsions. Nanoparticle-stabilized oil-in-water emulsions were continuously generated by co-injecting aqueous nanoparticle dispersion and oil through a beadpack. There exists a critical shear rate below which a stable emulsion will not be generated. The critical shear rate increased with decreasing bead size. Above the critical shear rate, the droplet size of the generated emulsion was a function of shear rate and decreased with increasing shear rate. The stable emulsions were characterized by their droplet size and rheology. The emulsion viscosity was highly dependent upon droplet size and not the bulk oil viscosity in the emulsion. The emulsions were highly shear thinning and emulsions with smaller droplets were more viscous than emulsions with larger droplets. Highly stable emulsions that were generated by co-injection were collected, separated from excess phase(s) and injected into beadpacks. In most experiments the injected emulsion coalesced into the bulk fluids. Whether the bulk fluids generated a new emulsion in the bead pack depended on the shear rate, bead size, and initial saturation of the beadpack. Different beadpack experiments showed the transition from one flow regime to a second flow regime as the slow movement of a coalescence/regeneration front propagated through the beadpack. Coreflood experiments confirmed the mechanisms hypothesized for the beadpack emulsion injection experiments. When a stable emulsion was injected the effluent emulsion rheology and droplet size were altered solely as a result of being forced through sandstone cores, not because of fluids contacted within the core. The shear rate controlled whether the emulsion coalesced and produced no effluent emulsion, regenerated into an emulsion with larger droplets, or regenerated into an emulsion with smaller droplets. Oil recovery experiments showed that nanoparticle-stabilized oil-in-water emulsion increased the recovery of oil compared to a waterflood for cores with immobile and mobile oil. The mechanism is the coalesced oil droplets form a flowing phase that is miscible with oil present in the core and thus achieves a much more efficient displacement. The possible continuous generation and coalescence of droplets may have increased the apparent viscosity, improving the sweep efficiency of the emulsion injection. A novel oil recovery mechanism was shown in imbibition experiments where nanoparticle dispersion was used to displace oil. Large shear rates coupled with the affinity for nanoparticles at the oil water interface enabled residual oil to be mobilized, or for residual oil blobs to spawn smaller droplets that are stabilized by the nanoparticles and thus can be transported with the dispersion through the core.Item Generative naming in Spanish-English bilingual speakers(2015-08) Quiroz, Jessica Margarita; Marquardt, Thomas P.; Pena, Elizabeth DThis study evaluated generative naming in Spanish English bilingual adults with three specific objectives: 1) to compare the total number of items generated by Spanish-English speakers in each language in the categories of food, clothes, and animals. 2) to examine the relationship between language proficiency levels on the translational equivalents in each category and across categories , and 3) to evaluate the relationship between the categories and the number of translational equivalents. Thirty-seven Spanish-English bilingual adult speakers were given 60 seconds to name as many items as possible in Spanish and English in three categories (food, clothes, and animals). Results reveal that participants generated more items in English than in Spanish for all categories. They produced the least number of items in the clothes category in both languages, but significantly more items for clothes and animals in English. Participants generated the least number of translational equivalents in the food category in both languages. Additionally, there was a negative effect of translational equivalents in the food category and proficiency levels. Finally, results indicate that participants generated significantly less translational equivalents for food than for clothes and animals, suggesting that balanced bilinguals will produce more unique items in highly salient categories. Future studies may consider using more sensitive language proficiency measure, as well as categories that are equally salient in both of the cultures of Spanish-English bilingual speakers.Item Internal gravity waves generated by tidal flow over topography(2012-12) Dettner, Amadeus Konstantin; Swinney, H. L., 1939-The majority of internal gravity wave energy in the ocean is produced by tidal flow over bottom topography. Regions of critical topography, where the topographic slope is equal to the slope of the internal gravity waves, is often believed to contribute most significantly to the radiated internal gravity wave power. Here, we present 2D computational studies of internal gravity wave generation by tidal flow over several types of topographic ridges. We vary the criticality parameter [epsilon], which is the ratio of the topographic slope to the wave beam slope, by independently changing the tidal frequency, stratification and topographic slope, which allows to study subcritical ([epsilon] < 1), critical ([epsilon] = 1), and supercritical ([epsilon] > 1) topography. This parameter variation allows us to explore a large range of criticality parameter, namely 0.1< [epsilon] < 10, as well as beam slope S, 0.05< S < 10. As in prior work [Zhang et al., Phys. Rev. Lett. (2008)], we observe resonant boundary currents for [epsilon] = 1. However, we find that the normalized radiated power monotonically increases with internal wave beam slope. We show that an appropriate normalization condition leads to a universal scaling of the radiated power that is proportional to the inverse of the beam slope 1/S and the tidal intensity I[subscript tide], except near [epsilon] = 1 where the behavior undergoes a transition. We characterize this transition and the overall scaling with the criticality parameter f([epsilon]), which is weak compared to the scalings mentioned before and only varies by a factor of two over the entire range of criticality parameter that we explored. Our results therefore suggest that estimates of the ocean energy budget must account for the strong scaling with the local beam slope, which dominates the conversion of tidal motions to internal wave energy. Thus we argue that detailed characterization of the stratification in the ocean is more important for global ocean models than high-resolution bathymetry to determine the criticality parameter.Item Laboratory and numerical studies of internal wave generation and propagation in the ocean(2010-08) King, Benjamin Thomas; Swinney, H. L., 1939-Internal waves are generated in the ocean by oscillating tidal flow over bottom topography such as ridges, seamounts, and continental slopes. They are similar to the more familiar surface waves, but not being constrained to move on the surface, propagate throughout the bulk of the world oceans. Internal waves transmit energy over thousands of kilometers, ultimately breaking and releasing their energy into turbulence and mixing. Where these internal waves are generated, as well as where and how they break and cause mixing, has important effects on the general circulation of the ocean, which is in turn a major component in earth's climate. As a first step in a more thorough understanding of the evolution of internal waves in the ocean, it is important to characterize their generation. The two-dimensional generation problem has been studied for four decades, with ample experimental, numerical, and theoretical results. Most of this past work has also been done using linear, inviscid approximations. However, wave generation in the ocean is three-dimensional (3D), and in many locations, nonlinear and viscous effects can be significant. Recent advances in experimental and numerical techniques are only now making the fully nonlinear, 3D generation process accessible. We utilize these new techniques to perform both laboratory experiments and numerical simulations on internal wave generation in 3D. We find that a significant component of the internal wave field generated by tidal flow over 3D topography is radiated in the direction perpendicular to the tidal forcing direction. This could lead to substantial improvements of global internal wave generation models. In addition, we have developed a new method for statistical analysis of ocean data sets, and have found large regions in the deep ocean where internal waves may not propagate. This will also have important effects on the way researchers study the propagation of internal waves, which, when propagating downward, were previously thought to always reflect from the sea floor.Item Procedural content generation of Angry Birds levels using Monte Carlo Tree Search(2016-12) Graves, Matthew, M.S. In Engineering; Caramanis, Constantine; Nagarajan, SarveshMonte Carlo Tree Search is a method for searching a decision-making process, usually employed in domains such as general game playing, where an artificial intelligence agent must decide the next move to make in a game simulation. There have been other domains that have been explored for MCTS, one of them being procedural level generation, which involves the automatic generation of game levels which are interesting to play, of an acceptable difficulty level, and not discernible from levels created by humans. In this report, I present a method for using MCTS to procedurally generate new Angry Birds levels, trained on a set of Angry Birds levels from existing games. This approach will scale for a requested level of difficulty by using multiple heuristics. I will examine the viability of the approach using playouts of AI agents on the generated levels, each with their own approach to winning the levels, used to simulate the experience level of human players (from naïve to advanced).