2,171 research outputs found

    Rotational spectrum of cis–cis HOONO

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    The pure rotational spectrum of cis-cis peroxynitrous acid, HOONO, has been observed. Over 220 transitions, sampling states up to J(')=67 and K-a(')=31, have been fitted with an rms uncertainty of 48.4 kHz. The experimentally determined rotational constants agree well with ab initio values for the cis-cis conformer, a five-membered ring formed by intramolecular hydrogen bonding. The small, positive inertial defect Delta=0.075667(60) amu A(2) and lack of any observable torsional splittings in the spectrum indicate that cis-cis HOONO exists in a well-defined planar structure at room temperature

    Rotational spectroscopy and dipole moment of cis-cis HOONO and DOONO

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    The rotational spectrum of cis-cis HOONO has been studied over a broad range of frequencies, 13–840 GHz, using pulsed beam Fourier-transform microwave spectroscopy and room-temperature flow cell submillimeter spectroscopy. The rotational spectrum of the deuterated isotopomer, cis-cis DOONO, has been studied over a subset of this range, 84–640 GHz. Improved spectroscopic constants have been determined for HOONO, and the DOONO spectrum is analyzed for the first time. Weak-field Stark effect measurements in the region of 84–110 GHz have been employed to determine the molecular dipole moments of cis-cis HOONO [µa=0.542(8) D,µb=0.918(15) D,µ=1.07(2) D] and DOONO [µa=0.517(9) D,µb=0.930(15) D,µ=1.06(2) D]. The quadrupole coupling tensor in the principal inertial axis system for the 14N nucleus has been determined to be chiaa=1.4907(25) MHz,chibb=–4.5990(59) MHz,chiab=3.17(147) MHz, and chicc=3.1082(59) MHz. Coordinates of the H atom in the center-of-mass frame have been determined with use of the Kraitchman equations, |aH|=0.516 Å and |bH|=1.171 Å. The inertial defects of HOONO and DOONO are consistent with a planar equilibrium structure with significant out-of-plane H atom torsional motion. Comparisons of the present results are made to ab initio calculations

    Plan Execution Interchange Language (PLEXIL) Software User's Manual

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    Plan Execution Interchange Language (PLEXIL) is a Core Flight System (or Core Flight Software) (cFS) based application, developed by the Autonomy Operating System project at NASA. cFS is open-source, reusable flight software, also developed by NASA and targeted to space missions. PLEXIL runs within the cFS framework, and is a wrapper integrating the open source PLEXIL Executive into the cFE (core Flight Executive) infrastructure. Software features include: Executes PLEXIL plans stored on local file system; Can be event-driven or clock-driven; and, Intended for "soft real time" discrete control

    Embedding Temporal Constraints For Coordinated Execution in Habitat Automation

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    Future NASA plans call for long-duration deep space missions with human crews. Because of light-time delay and other considerations, increased autonomy will be needed. This will necessitate integration of tools in such areas as anomaly detection, diagnosis, planning, and execution. In this paper we investigate an approach that integrates planning and execution by embedding planner-derived temporal constraints in an execution procedure. To avoid the need for propagation, we convert the temporal constraints to dispatchable form. We handle some uncertainty in the durations without it affecting the execution; larger variations may cause activities to be skipped

    Tidal restoration to reduce greenhouse gas emissions from freshwater impounded coastal wetlands

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    Freshwater impounded wetlands are created by artificially restricting coastal wetlands connection to tides. The decrease in salinity and altered hydrology can significantly increase greenhouse gas (GHG) emissions, specifically methane (CH4). Restoration of freshwater impounded wetlands through tidal reintroduction can potentially reduce GHG emissions; however, studies in tropical regions are scare. This study investigates the potential for tidal restoration of impounded freshwater coastal wetlands by comparing their GHG emissions with tidally connected mangrove and saltmarshes in the Burdekin catchment in Queensland, Australia. We found that freshwater impounded wetlands had significantly higher CH4 emissions (3,633  ± 812 μg CH4 m2 hour1) than mangroves (27 ± 8 μg CH4 m2 hour1 ) and saltmarsh (13  ± 8 μg CH4 m2 hour1 ). Soil redox, moisture, carbon, nitrogen, and bulk density were all significantly correlated to methane emissions. Conversely, freshwater impounded wetlands had significantly lower nitrous oxide (N2O) emissions (0.72  ± 0.18 μg N2O m2 hour1) than mangroves and saltmarsh (0.35  ± 0.29 and 1.32  ± 0.52 μg N2O m2 hour1 respectively). Nevertheless, when converting to CO2 equivalents (CO2-eq), freshwater impounded wetlands emitted 91  ± 20 g CO2-eq m2 hour1 , compared to the much lower 0.8  ± 0.2 and 0.7  ± 0.2 g CO2-eq m2 hour1 emission rates for mangroves and saltmarsh. In conclusion, restoration of freshwater impounded wetlands through tidal restoration is likely to result in reduced GHG emissions

    Geodatabase Development to Support Hyperspectral Imagery Exploitation

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    Geodatabase development for coastal studies conducted by the Naval Research Laboratory (NRL) is essential to support the exploitation of hyperspectral imagery (HSI). NRL has found that the remote sensing and mapping science community benefits from coastal classifications that group coastal types based on similar features. Selected features in project geodatabases relate to significant biological and physical forces that shape the coast. The project geodatabases help researchers understand factors that are necessary for imagery post processing, especially those features having a high degree of temporal and spatial variability. NRL project geodatabases include a hierarchy of environmental factors that extend from shallow water bottom types and beach composition to inland soil and vegetation characteristics. These geodatabases developed by NRL allow researchers to compare features among coast types. The project geodatabases may also be used to enhance littoral data archives that are sparse. This paper highlights geodatabase development for recent remote sensing experiments in barrier island, coral, and mangrove coast types

    Autonomy Operating System for UAVs: Pilot-in-a-Box

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    The Autonomy Operating System (AOS) is an open flight software platform with Artificial Intelligence for smart UAVs. It is built to be extendable with new apps, similar to smartphones, to enable an expanding set of missions and capabilities. AOS has as its foundations NASAs core flight executive and core flight software (cFEcFS). Pilot-in-a-Box (PIB) is an expanding collection of interacting AOS apps that provide the knowledge and intelligence onboard a UAV to safely and autonomously fly in the National Air Space, eventually without a remote human ground crew. Longer-term, the goal of PIB is to provide the capability for pilotless air vehicles such as air taxis that will be key for new transportation concepts such as mobility-on-demand. PIB provides the procedural knowledge, situational awareness, and anticipatory planning (thinking ahead of the plane) that comprises pilot competencies. These competencies together with a natural language interface will enable Pilot-in-a-Box to dialogue directly with Air Traffic Management from takeoff through landing. This paper describes the overall AOS architecture, Artificial Intelligence reasoning engines, Pilot-in-a-box competencies, and selected experimental flight tests to date

    Two-Minute Peripheral Motion Contrast Threshold Test Predicts Older Drivers’ Collisions and Hazardous Driving in Simulator

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    Older drivers’ contrast thresholds for low spatial frequency drifting Gabor stimuli at 15 degrees eccentricity were measured with a previously validated 10-minute forced-choice test and a 2-minute increasing contrast detection test (implemented on an iMac and a PC). Older drivers’ contrast thresholds significantly predict collisions, near collisions, hazardous lane excursions, and speeding, during a simulated drive with surprising hazard encounters and highway merging tasks. The 2-minute tests also correlate with each other and with the 10-minute test. The 2-minute tests are potentially suitable for use in an operational driver assessment setting

    Hanbury-Brown and Twiss Intensity Correlations of Parabosons

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    This paper shows that in intensity correlation measurements there will be clear and unambiguous signals that new-physics particles are, or aren't, parabosons. For a parabosonic field in a dominant single-mode, there is a diagonal P-representation in the "even and odd coherent states" basis. It is used to analyze zero-time-interval intensity correlations of parabosons in a maximum-entropic state. As the mean number of parabosons decreases, there is a monotonic reduction to (2/p) of the constant bosonic ``factor of two'' proportionality of the second-order versus the squared first-order intensity correlation function.Comment: 16 pages; version 4 to add simple p-independent recursion relatio
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