1,113 research outputs found

    Consistently Simulating a Wide Range of Atmospheric Scenarios for K2-18b with a Flexible Radiative Transfer Module

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    The atmospheres of small, potentially rocky exoplanets are expected to cover a diverse range in composition and mass. Studying such objects therefore requires flexible and wide-ranging modeling capabilities. We present in this work the essential development steps that lead to our flexible radiative transfer module, REDFOX, and validate REDFOX for the Solar system planets Earth, Venus and Mars, as well as for steam atmospheres. REDFOX is a k-distribution model using the correlated-k approach with random overlap method for the calculation of opacities used in the δ\delta-two-stream approximation for radiative transfer. Opacity contributions from Rayleigh scattering, UV / visible cross sections and continua can be added selectively. With the improved capabilities of our new model, we calculate various atmospheric scenarios for K2-18b, a super-Earth / sub-Neptune with ∼\sim8 M⊕_\oplus orbiting in the temperate zone around an M-star, with recently observed H2_2O spectral features in the infrared. We model Earth-like, Venus-like, as well as H2_2-He primary atmospheres of different Solar metallicity and show resulting climates and spectral characteristics, compared to observed data. Our results suggest that K2-18b has an H2_2-He atmosphere with limited amounts of H2_2O and CH4_4. Results do not support the possibility of K2-18b having a water reservoir directly exposed to the atmosphere, which would reduce atmospheric scale heights, hence too the amplitudes of spectral features inconsistent with the observations. We also performed tests for H2_2-He atmospheres up to 50 times Solar metallicity, all compatible with the observations.Comment: 28 pages, 13 figures, accepted for publication in Ap

    Geohydrologic Conditions at the Nuclear-fuels Reprocessing Plant and Waste-management Facilities at the Western New York Nuclear Service Center, Cattaraugus County, New York

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    A nuclear-fuel reprocessing plant, a high-level radioactive liquid-waste tank complex, and related waste facilities occupy 100 hectares (ha) within the Western New York Nuclear Service Center near West Valley, N.Y. The facilities are underlain by glacial and postglacial deposits that fill an ancestrial bedrock valley. The main plant facilities are on an elevated plateau referred to as the north plateau. Groundwater on the north plateau moves laterally within a surficial sand and gravel from the main plant building to areas northeast, east, and southeast of the facilities. The sand and gravel ranges from 1 to 10 m thick and has a hydraulic conductivity ranging from 0.1 to 7.9 m/day. Two separate burial grounds, a 4-ha area for low-level radioactive waste disposal and a 2.9-ha area for disposal of higher-level waste are excavated into a clay-rich till that ranges from 22 to 28 m thick. Migration of an organic solvent from the area of higher level waste at shallow depth in the till suggests that a shallow, fractured, oxidized, and weathered till is a significant pathway for lateral movement of groundwater. Below this zone, groundwater moves vertically downward through the till to recharge a lacustrine silt and fine sand. Within the saturated parts of the lacustrine unit, groundwater moves laterally to the northeast toward Buttermilk Creek. Hydraulic conductivity of the till, based on field and laboratory analyses , ranges from 0.000018 to 0.000086 m/day. (USGS

    Fast Non-Rigid Radiance Fields from Monocularized Data

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    3D reconstruction and novel view synthesis of dynamic scenes from collectionsof single views recently gained increased attention. Existing work showsimpressive results for synthetic setups and forward-facing real-world data, butis severely limited in the training speed and angular range for generatingnovel views. This paper addresses these limitations and proposes a new methodfor full 360{\deg} novel view synthesis of non-rigidly deforming scenes. At thecore of our method are: 1) An efficient deformation module that decouples theprocessing of spatial and temporal information for acceleration at training andinference time; and 2) A static module representing the canonical scene as afast hash-encoded neural radiance field. We evaluate the proposed approach onthe established synthetic D-NeRF benchmark, that enables efficientreconstruction from a single monocular view per time-frame randomly sampledfrom a full hemisphere. We refer to this form of inputs as monocularized data.To prove its practicality for real-world scenarios, we recorded twelvechallenging sequences with human actors by sampling single frames from asynchronized multi-view rig. In both cases, our method is trained significantlyfaster than previous methods (minutes instead of days) while achieving highervisual accuracy for generated novel views. Our source code and data isavailable at our project pagehttps://graphics.tu-bs.de/publications/kappel2022fast.<br

    A simple squeezer for removal of interstitial water from ocean sediments

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    A simple and inexpensive squeezer employed in the removal of interstitial water from ocean sediments has been designed. Squeezing is carried out with nitrogen at pressures of 500 to 1000 lb/in2 (35 to 70 kg/cm2). The apparatus is lined with teflon, thus insuring complete freedom from metallic contamination

    Modeling printed circuit board curvature in relation to manufacturing process steps

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    This paper presents an analytical method to predict deformations of Printed Circuit Boards (PCBs) in relation to their manufacturing process steps. Classical Lamination Theory (CLT) is used as a basis. The model tracks internal stresses and includes the results of subsequent production steps, such as bonding, multilayer press cycles and patterning processes. The aim of this research is to develop a model that can be applied to predict laminate deformations in the production of complex PCBs. Initial experimental results of simplified test specimens show that the modeling approach is valid and capable of accurately predicting laminate deformations for standard bi-layer bonding and multiple press cycles. In the future, the evolved model can be used to analyze PCB manufacturing processes and optimize PCB desig
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