715 research outputs found

    Growth rate and potential climate record from a rhodolith using C AMS

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    Toolset for Visual Creative Conflict Management

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    Conflict is neuro-physiologically processed by emotional faculties of the humanbrain, similarly to pain processing (Lack & Bogacz, 2012). Pain causes an away-reflex , and so does conflict. Most of us, therefore, try to avoid pain and likewise conflict. Some of us are drawn into conflict, either as an active party or a referee, against our will, while others of us must handle conflict as a matter of life role. Because of this away-reflex to conflict, we often try to resolve conflict in a single step in order to get it over with as quickly as possible. Many people expect to resolve a conflict in a single intervention (Elliott, d\u27Estrée & Kaufman, 2003). When that doesn\u27t work, our emotional response is amplified, typically including frustration, anger, and withdrawal. This project aims to provide a toolset that transitions a user\u27s handling of conflict from their emotional faculties to their logical faculties, overcoming the away-reflex. It also provides a visual representation of the conflict, which allows a conflict manager to logically plot and manage a multi-step resolution process with improved potential for long term results over the get-it-over-quickly single-step reflex. And, it comprises an open framework to which an expanding number of resources can be added to bolster a conflict manager\u27s understanding of all parties\u27 concerns, personalities, motivations, fears, and to enable the conflict manager to generate new ideas using Creative Problem Solving, and increase influence and persuasiveness

    Exoplanets imaging with a Phase-Induced Amplitude Apodization Coronagraph - I. Principle

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    Using 2 aspheric mirrors, it is possible to apodize a telescope beam without losing light or angular resolution: the output beam is produced by ``remapping'' the entrance beam to produce the desired light intensity distribution in a new pupil. We present the Phase-Induced Amplitude Apodization Coronagraph (PIAAC) concept, which uses this technique, and we show that it allows efficient direct imaging of extrasolar terrestrial planets with a small-size telescope in space. The suitability of the PIAAC for exoplanet imaging is due to a unique combination of achromaticity, small inner working angle (about 1.5 λ/d\lambda/d), high throughput, high angular resolution and large field of view. 3D geometrical raytracing is used to investigate the off-axis aberrations of PIAAC configurations, and show that a field of view of more than 100 λ/d\lambda/d in radius is available thanks to the correcting optics of the PIAAC. Angular diameter of the star and tip-tilt errors can be compensated for by slightly increasing the size of the occulting mask in the focal plane, with minimal impact on the system performance. Earth-size planets at 10 pc can be detected in less than 30s with a 4m telescope. Wavefront quality requirements are similar to classical techniques.Comment: 35 pages, 16 figures, Accepted for publication in Ap

    Capacity Improvement of Large, Two Stage Diaphragm Compressor

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    Case StudyTwo stage diaphragm compressor is used to pressurize a process gas stream. As delivered, compressor produced less than 75% of the required flow rate at the specified suction and discharge conditions. Improvement Goal: Increase capacity to deliver minimum required flow to the process. An improvement effort was initiated. This presentation covers the improvements made to the compressor which resulted in a capacity increase to 98% of the design flow rate. The OEM was integral to this process and provided the engineering and shop time to implement the improvements

    Simultaneous Exoplanet Characterization and deep wide-field imaging with a diffractive pupil telescope

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    High-precision astrometry can identify exoplanets and measure their orbits and masses, while coronagraphic imaging enables detailed characterization of their physical properties and atmospheric compositions through spectroscopy. In a previous paper, we showed that a diffractive pupil telescope (DPT) in space can enable sub-microarcsecond accuracy astrometric measurements from wide-field images by creating faint but sharp diffraction spikes around the bright target star. The DPT allows simultaneous astrometric measurement and coronagraphic imaging, and we discuss and quantify in this paper the scientific benefits of this combination for exoplanet science investigations: identification of exoplanets with increased sensitivity and robustness, and ability to measure planetary masses to high accuracy. We show how using both measurements to identify planets and measure their masses offers greater sensitivity and provides more reliable measurements than possible with separate missions, and therefore results in a large gain in mission efficiency. The combined measurements reliably identify potentially habitable planets in multiple systems with a few observations, while astrometry or imaging alone would require many measurements over a long time baseline. In addition, the combined measurement allows direct determination of stellar masses to percent-level accuracy, using planets as test particles. We also show that the DPT maintains the full sensitivity of the telescope for deep wide-field imaging, and is therefore compatible with simultaneous scientific observations unrelated to exoplanets. We conclude that astrometry, coronagraphy, and deep wide-field imaging can be performed simultaneously on a single telescope without significant negative impact on the performance of any of the three techniques.Comment: 15 pages, 6 figures. This second paper, following the paper describing the diffractive pupil telescope (DPT) astrometric technique, shows how simultaneous astrometry and coronagraphy observations, enabled by the DPT concept, constrain the orbital parameters and mass of exoplanet

    Conceptual Design of the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) for the Subaru Telescope

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    Recent developments in high-contrast imaging techniques now make possible both imaging and spectroscopy of planets around nearby stars. We present the conceptual design of the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS), a lenslet-based, cryogenic integral field spectrograph (IFS) for imaging exoplanets on the Subaru telescope. The IFS will provide spectral information for 140x140 spatial elements over a 1.75 arcsecs x 1.75 arcsecs field of view (FOV). CHARIS will operate in the near infrared (lambda = 0.9 - 2.5 microns) and provide a spectral resolution of R = 14, 33, and 65 in three separate observing modes. Taking advantage of the adaptive optics systems and advanced coronagraphs (AO188 and SCExAO) on the Subaru telescope, CHARIS will provide sufficient contrast to obtain spectra of young self-luminous Jupiter-mass exoplanets. CHARIS is in the early design phases and is projected to have first light by the end of 2015. We report here on the current conceptual design of CHARIS and the design challenges

    CHARIS Science: Performance Simulations for the Subaru Telescope's Third-Generation of Exoplanet Imaging Instrumentation

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    We describe the expected scientific capabilities of CHARIS, a high-contrast integral-field spectrograph (IFS) currently under construction for the Subaru telescope. CHARIS is part of a new generation of instruments, enabled by extreme adaptive optics (AO) systems (including SCExAO at Subaru), that promise greatly improved contrasts at small angular separation thanks to their ability to use spectral information to distinguish planets from quasistatic speckles in the stellar point-spread function (PSF). CHARIS is similar in concept to GPI and SPHERE, on Gemini South and the Very Large Telescope, respectively, but will be unique in its ability to simultaneously cover the entire near-infrared JJ, HH, and KK bands with a low-resolution mode. This extraordinarily broad wavelength coverage will enable spectral differential imaging down to angular separations of a few λ/D\lambda/D, corresponding to \sim0.\!\!''1. SCExAO will also offer contrast approaching 10510^{-5} at similar separations, \sim0.\!\!''1--0.\!\!''2. The discovery yield of a CHARIS survey will depend on the exoplanet distribution function at around 10 AU. If the distribution of planets discovered by radial velocity surveys extends unchanged to \sim20 AU, observations of \sim200 mostly young, nearby stars targeted by existing high-contrast instruments might find \sim1--3 planets. Carefully optimizing the target sample could improve this yield by a factor of a few, while an upturn in frequency at a few AU could also increase the number of detections. CHARIS, with a higher spectral resolution mode of R75R \sim 75, will also be among the best instruments to characterize planets and brown dwarfs like HR 8799 cde and κ\kappa And b.Comment: 13 pages, 7 figures, proceedings from SPIE Montrea

    Towards an optimal aiming for molten salt power towers

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    Finding a suitable aiming strategy for receivers of power towers can be challenging, especially for receivers using molten salt as heat transfer fluid as the allowable flux density decreases dramatically with increasing salt temperature. In this paper a very fast, steady-state model for the molten salt receiver is presented. This model is combined with a ray-tracing software and a metaheuristic optimization procedure. The thermal model is used to calculate the actual temperature and mass flow in the receiver which are then used to calculate the operational limits for the flux density. It is demonstrated that such an optimized aiming strategy can outperform a parameter based aiming strategies by more than 2%

    Mountain Rivers Reveal the Earthquake Hazard of Geologic Faults in Silicon Valley

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    The 1989, Mw = 6.9 Loma Prieta earthquake resulted in tens of lives lost and cost California almost 3% of its gross domestic product. Despite widespread damage, the earthquake did not clearly rupture the surface, challenging the identification and characterization of these hidden hazards. Here, we show that they can be illuminated by inverting fluvial topography for slip-and moment accrual-rates—fundamental components in earthquake hazard assessments—along relief-generating geologic faults. We applied this technique to thrust faults bounding the mountains along the western side of Silicon Valley in the San Francisco Bay Area, and discovered that these structures may be capable of generating a Mw = 6.9 earthquake every 250–300 years based on moment accrual rates. This method may be deployed broadly to evaluate seismic hazard in developing regions with limited geological and geophysical information
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