Modeling Morphology Evolution for Nanostructured Electrochemical Systems.

In this dissertation, we examine the morphological evolution of two nanostructured electrochemical systems, the growth of anodic alumina and the electrodeposition/electrodissolution of magnesium. These systems are investigated through one-dimensional and three-dimensional continuum simulations. Anodic alumina films are grown through an electrochemical oxidation process, exhibiting morphologies including barrier films and nanoporous films. A new model of anodization is developed in which a thin space charge region forms at the oxide/electrolyte interface, explaining experimental observations of embedded interfacial charge. Ionic transport through the oxide is described through a newly proposed counter-site defect mechanism. A one-dimensional model is parameterized and validated using experimental data in the literature. Predictions of the embedded charge as a function of applied current density and electrolyte pH are presented. The model is extended to multiple dimensions to simulate the growth of anodic nanopores. The simulations capture much of the experimental behavior for a range of applied potentials and electrolyte pH values. Most importantly, the simulated pore geometry is insensitive to the electrolyte pH, while still exhibiting the expected decreased growth rate for increasing pH. This improvement over previous models stems from the treatment of adsorbed oxygen and hydroxide species at the oxide/electrolyte interface. The second system examined is the electrodeposition/electrodissolution of magnesium. A new model of electrodeposition and electrodissolution is developed, which incorporates Butler-Volmer kinetics, facet evolution, and dilute solution theory. Three-dimensional simulations of the growth of magnesium deposits yield in-plane and out-of-plane hexagonal plates, consistent with experimental observations. Simulations predict that the deposits become narrower and taller with increasing current density due to the depletion of the electrolyte concentration near the deposits. Increasing the distance between the deposits causes increased depletion of the electrolyte surrounding the deposit. Different morphologies after one deposition-dissolution cycle, a flatted-topped hexagonal pyramid and a hexagonal plate, are predicted for two types of orientation dependence for the dissolution reaction. These predictions can be tested experimentally to identify the mechanisms governing the morphological evolution of magnesium. This work represents a step toward quantitatively predictive simulations of electrochemical systems through the development of improved models, their numerical implementation, and physical insights gained through simulations.PHDApplied PhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/116649/1/stvdwtt_1.pd

Candidate selection for the FLAMINGOS-2 galactic center survey

We present a JHK_s catalog of a 20'×20' region around the Galactic Center observed with the ISPI camera on the 4 m CTIO telescope. The data is being used to select targets for the FLAMINGOS-2 Galactic Center Survey, which will take near-infrared spectra of thousands of GC sources in an effort to identify and characterize the unique X-ray binary source population in this region

Quantum gravity at a TeV and the renormalization of Newton's constant

We examine whether renormalization effects can cause Newton¿s constant to change dramatically with energy, perhaps even reducing the scale of quantum gravity to the TeV region without the introduction of extra dimensions. We examine a model that realizes this possibility and describe experimental signatures from the production of small black holes

Understanding the implications of a changing environment on harvested bivalve populations using habitat suitability models

Habitat suitability models are useful to forecast how environmental change may affect the abundance or distribution of species of interest. In the case of harvested bivalves, those models may be used to estimate the vulnerability of this valued ecosystem good to stressors. Using literature-derived natural history information, rule-based habitat suitability models were constructed in a GIS for several bivalve species (Clinocardium nuttallii, Mya arenaria, and Tresus capax) that are recreationally and commercially harvested in NE Pacific estuaries, including in the Salish Sea. Spatially-explicit habitat maps were produced for two Oregon estuaries using environmental data (salinity, depth, sediment grain size, and burrowing shrimp density) from multiple studies (1960-2012). Habitat suitability values ranged from 1-4 (lowest to highest) depending on the number of environmental variables that fell within a bivalve’s tolerance limits. The models were tested by comparing the observed distribution of bivalves reported in benthic community studies (1996-2012) to the range of each suitability class. Results primarily showed that habitats of highest predicted suitability contained the greatest proportion of bivalve observations and highest population densities. Our model was further supported by logistic regression analyses that showed correspondence between predicted habitat suitability values and logistic model probabilities. We demonstrate how these models can be used as tools to forecast changes in the availability of suitable habitat for these species using projected changes in salinity and depth associated with environmental change scenarios. The advantage of this approach is that disparate, independent sets of existing data are sufficient to parameterize the models, and to produce and validate maps of habitat suitability. We believe that these models are transferable across estuaries (such as in the Salish Sea) and bivalve species, and thus can be applied to data-poor systems with only modest investment

Determining Effective Methods of Presenting Bayesian Problems to a General Audience

PhDThe thesis presents six experiments designed to further understanding of effective methods of presenting Bayesian problems to a general audience. The fi rst four experiments (Part I) focus on general Bayesian reasoning. The nal two experiments (Part II) focus speci fcally on the legal domain. Experiment one compares two leading theories for Bayesian presentation: Macchi's (2000) `nested sets' approach, and Krynski and Tenenbaum's (2007) `causal' approach. It also uses a think aloud protocol, requiring thought-process recording during solution. A nested sets framing effect is found, but no causal framing effect. From the think aloud data, a fi ve-stage solution process (the `nested sets' process), modal among successful individuals, is found. In experiment two, Macchi's approach is tested on a problem with greater ecological validity. An increase in accuracy is still seen. Experiment two also fi nds that conversion of the problem to integers by participants is highly associated with accuracy. Experiment three confi rms the null causal fi nding of experiment one and fi nds that the think aloud protocol itself increases accuracy. Experiment four experimentally tests whether prompting problem conversion to integers, and prompting individuals to follow the nested sets process improve accuracy. No effect is found for conversion, but an effect is found for the nested sets process prompt. Experiment fi ve tested whether statistically untrained individuals can undertake accurate Bayesian reasoning of a legal case including necessary forensic error rates (Fenton et al., 2014). No single individual is found to provide the normative answer. Instead a range of heuristics are found. Building upon this, experiment six compares two approaches to presenting the Bayesian output of a legal case: the popular event tree diagram, and the Bayesian network diagram recommended by (Fenton et al., 2014). Without inclusion of false positives and negatives the event-tree diagram was rated more trust worthy and easy to understand than the Bayesian network diagram. However, including these error types, this pattern reversed.European Research Council Advanced grant number ERC-2013-AdG339182-BAYES-KNOWLEDGE Engineering and Physical Sciences Research Council grant number EP/L50483X/1

Transforming uncertainty from a negative to a positive: assessing a novel intervention designed to increase uncertainty tolerance in individuals and teams

This paper, presented at the CIPD’s Applied Research Conference, uses a novel approach to explore whether tolerance to uncertainty in the workplace can be improved and therefore affect employee’s resilience, wellbeing, collaboration and sense of psychological safety

Thermally Modulated Fiber Sorbents for Rapidly Cycled Vacuum-Pressure Swing Adsorption of Post-Combustion Flue Gas

Thermally Modulated Fiber Sorbents for Rapidly Cycled Vacuum Pressure Swing Adsorption of Post Combustion Flue Gas Stephen J.A. DeWitt 339 Pages Directed by Dr. Ryan P. Lively The continued rise in the concentration of CO2 in the Earth’s atmosphere driven by society’s rising standard of living and continued reliance on carbon-containing fossil fuels has led to several significant environmental challenges, which will continue to face humanity in the coming decades and centuries. Developing technological solutions to accelerate the reduction of carbon dioxide emissions and curtail the effects of climate change will continue to serve one of the critical directions society will pursue to combat these effects. The capture of CO2 from point sources like coal-fired power plants will likely be a direction for the short and long-term reduction in emissions needed to stabilize the environment. With this in mind, developing technologies to serve this purpose with the least impact on people’s way of life serves as a critical challenge over the coming decades. The removal of CO2 from point sources has been an area of interest for a number of years now, with absorption technology appears best suited to make an immediate impact with pilot and full-scale plants currently being built. In the future, methods of separating and capturing CO2 will look to technologies with the potential to be considerably lower energy requirements, like adsorption and membranes, and these are still in the early stages of development. While these approaches lag behind absorption in technology readiness for CO2 capture today, the potential impact of their adoption in terms of cost reduction has led to considerable research investment in developing new materials and processes to enable their application. In this dissertation, a novel strategy is proposed, and materials are developed to enable the proposed process for post-combustion CO2 capture from coal. As part of this dissertation, four objectives were pursued to understand and enable this process. xxvii i) A process model was created and studied to develop a deeper understanding of the approach’s potential and the necessary materials developments to enable it. ii) Promising materials were synthesized and manufactured into ready-made devices for bench-scale testing. iii) Fundamental challenges of adsorptive separations related to heat management were considered in detail, and a novel manufacturing approach was developed to enable improvement in materials performance. iv) The potential of fiber sorbents for sub-ambient CO2 capture was examined through the operation of single bed PSA cycles using the manufactured materials from previous objectives. The first objective showed that a sub-ambient pressure-driven separation process, coupled with downstream liquefaction, could be used without the need for external refrigeration. Excess low-quality cooling could also be used for the dehydration of the flue gas, a key challenge facing adsorptive CO2 capture. This process would be significantly limited by its capital costs, consistent with expectation. Regardless of the separation considered, the capital and energy costs of pre- and post-treatment of CO2 lead to costs of CO2 capture exceeding $47/tonneCO2, and the best case study of sub-ambient pressure swing adsorption led to costs of capture around$60/tonneCO2. Preliminary analysis shows a more complicated process, where the post-treatment liquefaction is removed or replaced with a low-cost membrane or adsorbent system that could allow for additional cost reductions. The second objective focused on the production and spinning of MOF fiber sorbents, which showed the potential, in simulation, when combined with the work from objective 3 to reach 8-10x the performance of traditional pellet packed bed systems. Work here focused on the development of scale-up and manufacture of multiple MOF fiber xxviii sorbents, overcoming challenges in dope composition formulation and particle size resulting in sorbent leaching not previously reported in fiber sorbent spinning. The third objective focused on the development of a passive internal heat management strategy for pressure swing adsorption in the fiber sorbent morphology. Microencapsulated phase change materials were, for the first time, incorporated into fiber sorbents in the spinning step, allowing for a reduction in the manufacturing complexity of heat management in PSA systems. A 20-25% improvement in the breakthrough capacity of the sorbent and 30-40% reduction in amplitude of the thermal front prove the manufacturing process works and will enable more efficient sorbent performance. The final objective looked at the operation of a pressure swing adsorption unit for the removal of CO2 from simulated flue gas within the sub-ambient process framework. MOF fiber sorbents with and without phase change materials were compared in terms of the tradeoffs between purity, recovery, and CO2 productivity. This preliminary analysis showed there was much potential for sub-ambient CO2 capture, with productivities as high as 0.01 mol kg-1 sec-1 achieved using MOF fibers. Due to the single bed cycles used in these experiments, the recovery of the system suffered (never exceeding 45%), but future work focused on optimizing more complex cycles should allow for improvements in this area. Thermally modulated fiber adsorbents were also considered in the sub-ambient PSA system, showing higher purities and productivities than fibers without heat management at comparable recovery levels.Ph.D

Note and Comment

Suits Against Trustee; Bills and Notes--Nonnegotiable Notes--Liability of Indorser; Bonds--Joint Stock Association--Negotiability; Carriers--Free Transportation as a Penalty; Carriers--Waiver of Stipulations as to Suits; Constitutional Law--Due Process of Law--Indeterminate Sentence Law; Constitutional Law--Corporations--Foreign Corporations--Exclusion For Removal of Cause to Federal Courts; Constitutional Law--Powers of Constitutional Convention; Criminal Law--Capital Offense--Bail--When Granted; Criminal Law--Murder--Elements of Murder; Damages--Action by Husband for Loss of Wife\u27s Services; Damages--Failure to Deliver Telegram--Mental Suffering--Near Relative; Deeds--Joinder of Infant Husband; Divorce--Temporary Alimony and Counsel Fees--Appeal--Decisions Reviewable; Equity--Sworn Answers as Evidence--Proof to Overcome; Evidence--Opinion Evidence in Action for Libel; Evidence--The Best Evidence Rule; Fraudulent Conveyances--Delivery and Change of Possession of Growing Crops; Garnishment--Exemption--Proceeds of Insurance; Infants--Disaffirming Deed--Ejectment; Judgment--Enjoining Execution on Dormant Judgment; Master and Servant--Liability of Master to Servant for Injury Due to Defective Machinery-

The Path to Buried Treasure: Paving the Way to the FLAMINGOS-2 Galactic Center Survey with IR and X-ray Observations

I describe the IR and X-ray campaign we have undertaken to determine the nature of the faint discrete X-ray source population discovered by Chandra in the Galactic Center. These results will provide the input to the FLAMINGOS-2 Galactic Center Survey (F2GCS). With FLAMINGOS-2's multi-object IR spectrograph we will obtain 1000s of IR spectra of candidate X-ray source counterparts, allowing us to efficiently identify the nature of these sources, and thus dramatically increase the number of known X-ray binaries and CVs in the Milky Way.Comment: To be published in Proceedings of 'A Population Explosion: The Nature and Evolution of X-ray Binaries in Diverse Environments', 28 Oct - 2 Nov, St. Pete Beach, FL; eds. R.M. Bandyopadhyay, S. Wachter, D. Gelino, C.R. Gelino; AIP Conference Proceedings Serie