Groundwater geology of White County, Illinois

Includes bibliographical references (p. 38)

Observations of Continuous Quasiperiodic Auroral Pulsations on Saturn in High Time-Resolution UV Auroral Imagery

Saturn's aurora represents the ionospheric response to plasma processes occurring in the planet's entire magnetosphere. Short-lived ∼1-hr quasiperiodic high-energy electron injections, frequently observed in in situ particle and radio measurements, should therefore entail an associated flashing auroral signature. This study uses high time-resolution ultraviolet (UV) auroral imagery from the Cassini spacecraft to demonstrate the continuous occurrence of such flashes in Saturn's northern hemisphere and investigate their properties. We find that their recurrence periods of order 1 hr and preferential occurrence near dusk match well with previous observations of electron injections and related auroral hiss features. A large spread in UV auroral emission power, reaching more than 50% of the total auroral power, is observed independent of the flash locations. Based on an event observed both by the Hubble Space Telescope and the Cassini spacecraft, we propose that these auroral flashes are not associated with low-frequency waves and instead directly caused by recurrent small-scale magnetodisc reconnection on closed field lines. We suggest that such reconnection processes accelerate plasma planetward of the reconnection site toward the ionosphere inducing transient auroral spots while the magnetic field rapidly changes from a bent-back to a more dipolar configuration. This manifests as a sawtooth-shaped discontinuity observed in magnetic field data and indicates a release of magnetospheric energy through plasmoid release

Constraints on Pluto’s H and CH₄ profiles from New Horizons Alice Lyα observations

The Alice spectrograph on New Horizons performed several far-ultraviolet (FUV) airglow observations during the July 2015 flyby of Pluto. One of these observations, named PColor2, was a short (226 s) scan across the dayside disk of Pluto from a range of ∼34,000 km, at about 40 minutes prior to closest approach. The brightest observed FUV airglow signal at Pluto is the Lyman alpha (Lyα) emission line of atomic hydrogen, which arises primarily through the resonant scattering of solar Lyα by H atoms in the upper atmosphere, with a brightness of about 30 Rayleighs. Pluto appears dark against the much brighter (∼100 Rayleigh) sky background; this sky background is likewise the result of resonantly scattered solar Lyα, in this case by H atoms in the interplanetary medium (IPM). Here we use an updated photochemical model and a resonance line radiative transfer model to perform detailed simulations of the Lyα emissions observed in the Alice PColor2 scan. The photochemical models show that H and CH₄ abundances in Pluto’s upper atmosphere are a very strong function of the near-surface mixing ratio of CH₄, and could provide a useful way to remotely monitor seasonal climate variations in Pluto’s lower atmosphere. The morphology of the PColor2 Lyα emissions provides constraints on the current abundance profiles of H atoms and CH₄ molecules in Pluto’s atmosphere, and indicate that the globally averaged near-surface mixing ratio of CH₄ is currently close to 0.4%. This new result thus provides independent confirmation of one of the primary results from the solar occultation, also observed with the New Horizons Alice ultraviolet spectrograph

Constraints on Pluto’s H and CH₄ profiles from New Horizons Alice Lyα observations

The Alice spectrograph on New Horizons performed several far-ultraviolet (FUV) airglow observations during the July 2015 flyby of Pluto. One of these observations, named PColor2, was a short (226 s) scan across the dayside disk of Pluto from a range of ∼34,000 km, at about 40 minutes prior to closest approach. The brightest observed FUV airglow signal at Pluto is the Lyman alpha (Lyα) emission line of atomic hydrogen, which arises primarily through the resonant scattering of solar Lyα by H atoms in the upper atmosphere, with a brightness of about 30 Rayleighs. Pluto appears dark against the much brighter (∼100 Rayleigh) sky background; this sky background is likewise the result of resonantly scattered solar Lyα, in this case by H atoms in the interplanetary medium (IPM). Here we use an updated photochemical model and a resonance line radiative transfer model to perform detailed simulations of the Lyα emissions observed in the Alice PColor2 scan. The photochemical models show that H and CH₄ abundances in Pluto’s upper atmosphere are a very strong function of the near-surface mixing ratio of CH₄, and could provide a useful way to remotely monitor seasonal climate variations in Pluto’s lower atmosphere. The morphology of the PColor2 Lyα emissions provides constraints on the current abundance profiles of H atoms and CH₄ molecules in Pluto’s atmosphere, and indicate that the globally averaged near-surface mixing ratio of CH₄ is currently close to 0.4%. This new result thus provides independent confirmation of one of the primary results from the solar occultation, also observed with the New Horizons Alice ultraviolet spectrograph

Origin and Health Impacts of Emissions of Toxic By-Products and Fine Particles from Combustion and Thermal Treatment of Hazardous Wastes and Materials

High-temperature, controlled incineration and thermal treatment of contaminated soils, sediments, and wastes at Superfund sites are often preferred methods of remediation of contaminated sites under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 and related legislation. Although these methods may be executed safely, formation of toxic combustion or reaction by-products is still a cause of concern. Emissions of polycyclic aromatic hydrocarbons (PAHs); chlorinated hydrocarbons (CHCs), including polychlorinated dibenzo-p-dioxins and dibenzofurans; and toxic metals (e.g., chromium VI) have historically been the focus of combustion and health effects research. However, fine particulate matter (PM) and ultrafine PM, which have been documented to be related to cardiovascular disease, pulmonary disease, and cancer, have more recently become the focus of research. Fine PM and ultrafine PM are effective delivery agents for PAHs, CHCs, and toxic metals. In addition, it has recently been realized that brominated hydrocarbons (including brominated/chlorinated dioxins), redox-active metals, and redox-active persistent free radicals are also associated with PM emissions from combustion and thermal processes. In this article, we discuss the origin of each of these classes of pollutants, the nature of their association with combustion-generated PM, and the mechanisms of their known and potential health impacts

Titan airglow spectra from Cassini Ultraviolet Imaging Spectrograph (UVIS): EUV analysis

peer reviewedaudience: researcher, professional, studentWe present the first UV airglow observations of Titan's atmosphere by the Ultraviolet Imaging Spectrograph (UVIS) on Cassini. Using one spectral channel in the EUV from 561-1182 Å and one in the FUV from 1115-1913 Å, UVIS observed the disk on 13 December, 2004 at low solar activity. The EUV spectrum consists of three band systems of N[SUB]2[/SUB] (b [SUP]1[/SUP]∏[SUB]u[/SUB], b' [SUP]1[/SUP]∑[SUB]u[/SUB] [SUP]+[/SUP], c[SUB]4[/SUB]' [SUP]1[/SUP]∑[SUB]u[/SUB] [SUP]+[/SUP] -> X [SUP]1[/SUP]∑[SUB]g[/SUB] [SUP]+[/SUP]), while the FUV spectrum consists of one (a [SUP]1[/SUP]∏[SUB]g[/SUB] -> X [SUP]1[/SUP]∑[SUB]g[/SUB] [SUP]+[/SUP]). Both the EUV and FUV spectra contain many N I and N II multiplets that are produced primarily by photodissociative ionization. Spectral intensities of the N[SUB]2[/SUB] c[SUB]4[/SUB]' [SUP]1[/SUP]∑[SUB]u[/SUB] [SUP]+[/SUP](v' = 0) -> X [SUP]1[/SUP]∑[SUB]g[/SUB] [SUP]+[/SUP](v'' = 0-2) progression from 950-1010 Å are resolved for the first time. The UVIS observations reveal that the c[SUB]4[/SUB]' [SUP]1[/SUP]∑[SUB]u[/SUB] [SUP]+[/SUP](0) -> X [SUP]1[/SUP]∑[SUB]g[/SUB] [SUP]+[/SUP] (0) vibrational band near 958 Å is weak and undetectable, and that N I multiplets near 953.2 and 964.5 Å are present instead. Magnetospheric particle excitation may be weak or sporadic, since the nightside EUV spectrum on this orbit shows no observable nitrogen emission features and only H Ly-β

Task-based resource allocation for improving the reusability of redundant manipulators

textBecause of its increased range of resources, a redundant/reconfigurable robot has the potential to be deployed for a variety of applications saving time and money. This work provides decision tools which increase the utility of deployed manipulators by operating them intuitively and economically in terms of a broader set of tasks while maximizing performance. System utility is expanded by developing a general decision making strategy that decreases the burden on operators who have little or no robotics expertise yet must operate the system. This utility function is a Redundancy Resolution Strategy. (RRS) The RRS uses a generalized, parametric system manipulator model and a large set of criteria to compare the capabilities of the infinite number of joint configurations available. The RRS then selects and prioritizes a subset of criteria that are appropriate in a given situation by evaluating critical boundaries associated with manipulator constraints and/or task description. The RRS is paired with a Redundancy Resolution Technique (RRT) which determines, in real- vii time, the best configuration in terms of the selected criteria. Together, the criteria and these components are the Decision Making System (DMS). Most DMS components have received attention at the University of Texas and elsewhere, but the RRS and component integration has been largely dismissed as implementation detail. This ‘detail’ is largely responsible for the lack of success in deploying redundant/reconfigurable systems. If the advantages of these systems are to be realized, we must apply physically meaningful criteria to determine the best allocation of redundant resources by creating a procedure to select a subset of appropriate criteria. The selected criteria must improve performance so that a larger number of tasks are possible. The burden on the operator, task completion time, and time required to prepare for a new task all must be reduced. The life of the manipulator is also increased by using resources efficiently. By managing resource allocation correctly, the RRS can also remove the need for intervention by an expensive ‘robotics expert.’ The selected RRT, reviewed performance criteria, and proposed RRS are implemented using existing operational software and used to complete several complex simulated tasks.Mechanical Engineerin