Biological Assessments of Six Selected Fishes, Amphibians, and Mussels in Illinois

ID: 8758; issued November 1, 1996INHS Technical Report prepared for Illinois Department of Natural Resources, Division of Natural Heritag

Concepts and procedures used to determine certain sea wave characteristics

A technique and its application are presented by which wave parameters, critical to spacecraft water impact load analysis, may be determined

Elemental and isotopic fractionation in 3He-rich solar energetic particle events

Using data from the Solar Isotope Spectrometer (SIS) on the Advanced Composition Explorer (ACE) mission, heavy ion composition measurements have been made in 26^3He-rich solar energetic particle (SEP) events that occurred between 1998 and 2004. Relative abundances of 13 elements from C through Ni have been investigated, as have the isotopic compositions of the elements Ne and Mg. We find a general tendency for the abundances to follow trends similar to those found in gradual SEP events, in which fractionation can be represented in the form of a power-law in Q/M. However several deviations from this pattern are noted that may provide useful diagnostics of the acceleration process occurring in solar flares

Decision Support Design for Workload Mitigation in Human Supervisory Control of Multiple Unmanned Aerial Vehicles

As UAVs become increasingly autonomous, the multiple personnel currently required to operate a single UAV may eventually be superseded by a single operator concurrently managing multiple UAVs. Instead of lower-level tasks performed by today’s UAV teams, the sole operator would focus on high-level supervisory control tasks such as monitoring mission timelines and reacting to emergent mission events. A key challenge in the design of such single-operator systems will be the need to minimize periods of excessive workload that could arise when critical tasks for several UAVs occur simultaneously. To a certain degree, it is possible to predict and mitigate such periods in advance. However, actions that mitigate a particular period of high workload in the short term may create long term episodes of high workload that were previously non-existent. Thus some kind of decision support is needed that facilitates an operator’s ability to evaluate different options for managing a mission schedule in real-time. This paper describes two decision support visualizations designed for supervisory control of four UAVs performing a time-critical targeting mission. A configural display common to both visualizations, named the StarVis, was designed to highlight potential periods of high workload corresponding to the current mission timeline, as well as “what if” projections of possible high workload periods based upon different operator options. The first visualization design allows an operator to compare different high workload mitigation options for individual UAVs. This is termed the local visualization. The second visualization is indicates the combined effects of multiple high workload mitigation decisions on the timeline. This is termed the global visualization. The main advantage of the local visualization is that options can be compared directly; however, the possible effects of these options on the mission timeline are only indicated for the individual UAV primarily affected by the decision. For the global visualization, different decisions can be combined to show possible effects on the system propagated across all UAVs, but the different alternatives of a single decision option alternative cannot be directly compared. An experiment was conducted testing these visualizations against a control with no visualization. Results showed that subject using the local visualization had better performance, higher situational awareness, and no significant increase in workload over the other two experimental conditions. This occurred despite the fact that the local and global StarVis displays were very similar. Not only did the Global StarVis produce degraded results as compared to the local StarVis, but those participants with no visualization performed as well as those with the global StarVis. This disparity in performance despite strong visual similarities in the StarVis designs is attributed to operators’ inability to process all the information presented in the global StarVis as well as the fact that participants with the local StarVis were able to rapidly develop effective cognitive problem strategies. This research effort highlights a very important design consideration, in that a single decision support design can produce very different performance results when applied at different levels of abstraction.Prepared for Kevin Burns, The MITRE Corporatio

Heavy-ion Fractionation in the Impulsive Solar Energetic Particle Event of 2002 August 20: Elements, Isotopes, and Inferred Charge States

Measurements of heavy-ion elemental and isotopic composition in the energy range ~12-60 MeV nucleon^(–1) are reported from the Advanced Composition Explorer/Solar Isotope Spectrometer (ACE/SIS) instrument for the solar energetic particle (SEP) event of 2002 August 20. We investigate fractionation in this particularly intense impulsive event by examining the enhancements of elemental and isotopic abundance ratios relative to corresponding values in the solar wind. The elemental enhancement pattern is similar to those in other impulsive events detected by ACE/SIS and in compilations of average impulsive-event composition. For individual elements, the abundance of a heavy isotope (mass M_2) is enhanced relative to that of a lighter isotope (M_1) by a factor ~(M_(1)/M_2)^α with α ≃ 15. Previous studies have reported elemental abundance enhancements organized as a power law in Q/M, the ratio of estimated ionic charge to mass in the material being fractionated. We consider the possibility that a fractionation law of this form could be responsible for the isotopic fractionation as a power law in the mass ratio and then explore the implications it would have for the ionic charge states in the source material. Assuming that carbon is fully stripped (Q_C = 6), we infer mean values of the ionic charge during the fractionation process, Q_Z , for a variety of elements with atomic numbers 7 ≤ Z ≤ 28. We find that Q_(Fe) ≃ 21-22, comparable to the highest observed values that have been reported at lower energies in impulsive SEP events from direct measurements near 1 AU. The inferred charge states as a function of Z are characterized by several step increases in the number of attached electrons, Z – Q_Z . We discuss how this step structure, together with the known masses of the elements, might account for a variety of features in the observed pattern of elemental abundance enhancements. We also briefly consider alternative fractionation laws and the relationship between the charge states we infer in the source material and those derived from in situ observations

Analytical model of non-Markovian decoherence in donor-based charge quantum bits

We develop an analytical model for describing the dynamics of a donor-based charge quantum bit (qubit). As a result, the quantum decoherence of the qubit is analytically obtained and shown to reveal non-Markovian features: The decoherence rate varies with time and even attains negative values, generating a non-exponential decay of the electronic coherence and a later recoherence. The resulting coherence time is inversely proportional to the temperature, thus leading to low decoherence below a material dependent characteristic temperature.Comment: 19 pages, 3 figure

STEREO and ACE Observations of Energetic Particles from Corotating Interaction Regions

Since early 2007, significant particle enhancements due to corotating interaction regions (CIRs) have regularly appeared at 1 AU without any appreciable contamination from solar energetic particles (SEPs). In 2009 the prevalence of CIRs diminished as the maximum speed of the high speed solar wind streams in the ecliptic decreased along with the tilt of the heliospheric current sheet. Observations of CIR time profiles at different longitudes from STEREO show delays between the Behind and Ahead spacecraft that are often roughly as expected from the corotation time lag, although small differences in the spacecraft latitudes introduce significant scatter in the time delays. In some cases different features seen at Ahead and Behind suggest that transient disturbances in the solar wind may alter connection to or transport from the shock, or that temporal changes occur in the CIR shock itself. H and He data from STEREO/LET at 1.8–6 MeV/nucleon show that 1) the CIR spectral index at these energies is ~−4, independent of intensity but with considerable variability, 2) the He/H ratio is ~0.03 for larger CIRs but varies systematically with energy and event intensity, and 3) although the correlation between the CIR MeV particle increases and solar wind speed is generally good, many times a high-speed stream is not associated with MeV particles, while at other times a recurring series of CIR particle increases appears only at higher energies and may be associated with current sheet crossings and low speed solar wind

Transmission loss predictions for dissipative silencers of arbitrary cross section in the presence of mean flow

A numerical technique is developed for the analysis of dissipative silencers of arbitrary, but axially uniform, cross section. Mean gas flow is included in a central airway which is separated from a bulk reacting porous material by a concentric perforate screen. The analysis begins by employing the finite element method to extract the eigenvalues and associated eigenvectors for a silencer of infinite length. Point collocation is then used to match the expanded acoustic pressure and velocity fields in the silencer chamber to those in the inlet and outlet pipes. Transmission loss predictions are compared with experimental measurements taken for two automotive dissipative silencers with elliptical cross sections. Good agreement between prediction and experiment is observed both without mean flow and for a mean flow Mach number of 0.15. It is demonstrated also that the technique presented offers a considerable reduction in computational expenditure when compared to a three dimensional finite element analysis