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  • 1
    Publication Date: 2019-01-28
    Type: http://purl.org/eprint/type/ConferencePaper
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  • 2
    Publication Date: 2019-01-31
    Description: We present consistent annual mean atmospheric histories and growth rates for the mainly anthropogenic halogenated compounds HCFC-22, HCFC-141b, HCFC-142b, HFC-134a, HFC-125, HFC-23, PFC-14 and PFC-116, which are all potentially useful oceanic transient tracers (tracers of water transport within the ocean), for the Northern and Southern Hemisphere with the aim of providing input histories of these compounds for the equilibrium between the atmosphere and surface ocean. We use observations of these halogenated compounds made by the Advanced Global Atmospheric Gases Experiment (AGAGE), the Scripps Institution of Oceanography (SIO), the Commonwealth Scientific and Industrial Research Organization (CSIRO), the National Oceanic and Atmospheric Administration (NOAA) and the University of East Anglia (UEA). Prior to the direct observational record, we use archived air measurements, firn air measurements and published model calculations to estimate the atmospheric mole fraction histories. The results show that the atmospheric mole fractions for each species, except HCFC-141b and HCFC-142b, have been increasing since they were initially produced. Recently, the atmospheric growth rates have been decreasing for the HCFCs (HCFC-22, HCFC-141b and HCFC-142b), increasing for the HFCs (HFC-134a, HFC-125, HFC-23) and stable with little fluctuation for the PFCs (PFC-14 and PFC-116) investigated here. The atmospheric histories (source functions) and natural background mole fractions show that HCFC-22, HCFC-141b, HCFC-142b, HFC-134a, HFC-125 and HFC-23 have the potential to be oceanic transient tracers for the next few decades only because of the recently imposed bans on production and consumption. When the atmospheric histories of the compounds are not monotonically changing, the equilibrium atmospheric mole fraction (and ultimately the age associated with that mole fraction) calculated from their concentration in the ocean is not unique, reducing their potential as transient tracers. Moreover, HFCs have potential to be oceanic transient tracers for a longer period in the future than HCFCs as the growth rates of HFCs are increasing and those of HCFCs are decreasing in the background atmosphere. PFC-14 and PFC-116, however, have the potential to be tracers for longer periods into the future due to their extremely long lifetimes, steady atmospheric growth rates and no explicit ban on their emissions. In this work, we also derive solubility functions for HCFC-22, HCFC-141b, HCFC-142b, HFC-134a, HFC-125, HFC-23, PFC-14 and PFC-116 in water and seawater to facilitate their use as oceanic transient tracers. These functions are based on the Clark–Glew–Weiss (CGW) water solubility function fit and salting-out coefficients estimated by the poly-parameter linear free-energy relationships (pp-LFERs). Here we also provide three methods of seawater solubility estimation for more compounds. Even though our intention is for application in oceanic research, the work described in this paper is potentially useful for tracer studies in a wide range of natural waters, including freshwater and saline lakes, and, for the more stable compounds, groundwaters.
    Type: Article , PeerReviewed
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  • 3
    Publication Date: 2019-01-31
    Description: The sedimentary model of coastal deposits in eastern Rhodes over the last 2 Ma is refined and improved in accuracy. New field investigations and U/Th dating of Spondylus bivalve shells, combined with micropalaeontological and sedimentological data, allow the recognition of four synthems separated by major erosional surfaces. We present here evidence for two of these erosional surfaces. This new model allows the identification and quantification of the vertical movements recorded by the studied exposures. The history of these vertical motions is characterized by two periods of uplift and two periods of subsidence. Such an evolution is unique at the regional scale in the eastern Hellenic forearc. We interpret these results as reflecting the individualization of Rhodes as a single tectonic block during increasing trench bending. This trench bending is accommodated by an increase in the curvature of the forearc during the last 2 Ma.
    Type: Article , PeerReviewed
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  • 4
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    Optical Society of America
    In:  Applied Optics, 55 (27). pp. 7756-7762.
    Publication Date: 2019-01-31
    Description: The structure of a light field in sea water excited by a unidirectional point-sized pulsed source is studied by Monte Carlo technique. The pulse shape registered at the distances up to 120 m from the source on the beam axis and in its axial region is calculated with a time resolution of 1 ps. It is shown that with the increase of the distance from the source the pulse splits into two parts formed by components of various scattering orders. Frequency and phase responses of the beam are calculated by means of the fast Fourier transform. It is also shown that for higher frequencies, the attenuation of harmonic components of the field is larger. In the range of parameters corresponding to pulse splitting on the beam axis, the attenuation of harmonic components in particular spectral ranges exceeds the attenuation predicted by Bouguer law. In this case, the transverse distribution of the amplitudes of these harmonics is minimal on the beam axis.
    Type: Article , PeerReviewed
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  • 5
    Publication Date: 2019-01-31
    Description: Abstract High-latitude cold-water coral reefs are particularly vulnerable to climate change due to enhanced CO2 uptake in these regions. To evaluate their physiological functioning and potential application as pH archives, we retrieved both recent and fossil samples of Lophelia pertusa along the Norwegian margin from Oslofjord (59°N), over to Trondheimsfjord, Sula and Lopphavet (70.6°N). Boron isotope analyses (δ11B) were undertaken using solution-based and laser ablation multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS; LA-ICP-MS), and secondary ion mass spectrometry (SIMS). Epi-fluorescence microscopy was employed to provide a rapid pre-screening routine for structure-specific subsampling in the coral skeleton. This integrated approach enabled us to assess heterogeneities within single specimens, as well as to investigate the role of local environmental influences including recent and past variations. All three mass spectrometry methods show substantial differences in the δ11B of the theca wall (TW) and the centres of calcification (COC's). Micro-bulk subsamples milled from the theca wall of modern specimens originating from different habitats but with comparable seawater pH (8–8.16) gave consistent δ11B values averaging 26.7 (±0.2‰, 2σ, n = 4), while COC subsamples systematically deviated towards lower B/Ca (by ~40%) and depleted δ11B values (minimum 22.7 ± 0.3‰, 2σ), implying a difference of at least 4‰ between TW and COC. SIMS and LA-ICP-MS measurements identified much larger internal heterogeneities with maximum variation of ~10‰ between the distinct skeletal structures; minimal SIMS δ11B values of ~17.3 ± 1.2‰ (2σ) were associated with the pure COC material. Our findings may be interpreted in terms of the occurrence of two main, but likely different, biomineralisation mechanisms in L. pertusa, with the COC's generally exhibiting minimal pH up-regulation, potentially supporting the use of bicarbonate in the early stages of biomineralisation. Furthermore, we highlight the potential utility of L. pertusa for palaeo-proxy studies if targeting the compositionally homogenous TW zones devoid of COC admixtures, which appear to provide highly reproducible measurements.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 6
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    In:  Abstracts | International Conference on Coupled Processes in Fractured Geological Media: Observation, Modeling, and Application – CouFrac #
    Publication Date: 2019-02-01
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  • 7
    Publication Date: 2019-02-01
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  • 8
    Publication Date: 2019-02-01
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  • 9
    Publication Date: 2019-02-01
    Description: Hydraulic fracturing tests on cubic granite samples with a side length of 50 mm were conducted under a true tri-axial test equipment combined with acoustic emission (AE) monitoring. The applied three principal stresses are 20 MPa (��v), 20 MPa (��H) and 10 MPa (��h), respectively. Experimental results show that cyclic hydraulic fracturing (CHF) can help reduce breakdown pressure as well as induced seismicity, compared to the conventional hydraulic fracturing. However, injectivity enhancement effect is less pronounced. Re-injection tests were conducted on the fractured samples by applying multiple incremental injection rates step-by-step. Propagation of existing fractures and creation of new fractures were confirmed, without inducing larger AE compared to continuous injection. Moreover, based on computed tomography (CT) imaging, fractures along grain boundaries are more frequently observed in CHF, particularly at large number of cycles and re-injection tests with multiple injection rates. Fractures cutting across mineral grains dominate as a result of conventional HF.
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  • 10
  • 11
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    Publication Date: 2019-02-01
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  • 12
    Publication Date: 2019-01-31
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  • 13
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    In:  Veröffentlichungen / Deutsche Geodätische Kommission. Reihe C, Dissertationen ; Heft Nr. 829
    Publication Date: 2019-01-31
    Type: http://purl.org/eprint/type/Thesis
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  • 14
    Publication Date: 2019-02-01
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  • 15
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    In:  Abstract booklet | 15th International Symposium on Equatorial Aeronomy #
    Publication Date: 2019-01-31
    Type: http://purl.org/eprint/type/ConferencePaper
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  • 16
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    In:  Proceedings | 10th International Conference on Ecological Informatics: translating ecological data into knowledge and decisions in a rapidly changing world’#
    Publication Date: 2019-01-31
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  • 17
    Publication Date: 2019-02-01
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  • 18
    Publication Date: 2019-02-01
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  • 19
    Publication Date: 2019-01-31
    Type: http://purl.org/escidoc/metadata/ves/publication-types/article
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  • 20
    Publication Date: 2019-01-31
    Description: Water-rock interactions are sorption-, dissolution-, precipitation-, and redox reactions at the interface between rock matrix and water. In aquifer thermal energy storage (ATES) systems, certain water-rock interactions can have undesired consequences, such as clogging of aquifer pores or contaminant release, and are therefore geochemical risks. Their prediction and prevention requires site-specific knowledge about water-rock interactions at specific operational conditions. This study investigates the reactivity of two pyrite-bearing siliciclastic rocks from the Hettangian and Lower Sinemurian stages of the Lower Jurassic. They are associated with the heat storage aquifer of the ATES system at the German parliament buildings in the city of Berlin, which is located in the south-eastern part of the Northeast German Basin. The study presents a workflow to (a) describe mineralogy and sorption reactions at the rock surface, (b) quantify the maximum of potentially critical (mineral-forming/contaminant) elements that can be released from the rocks, (c) determine their phase association and release mechanisms, and (d) identify the most important control parameters and process interactions during heat storage. The bulk mineralogy was identified by X-ray diffraction, X-ray fluorescence and scanning electron microscopy. Potentially critical mobile elements and easily soluble crystalline and amorphous solid phases, such as hydroxides and sulfides, were quantified with a specifically developed sequential extraction. This method allows the partition of mobile elements by association with specific rock fractions with the help of appropriate solvents. These fractions are (1) exchangeable (2) associated with acid-soluble phases (carbonates), (3) associated with reducible phases (oxides/hydroxides), and (4) associated with oxidizable phases (organic matter/sulfides). Heat storage, defined by temperatures of up to 90 °C and potential intrusion of oxygen into the aquifer, was investigated by steady-state leaching experiments with simplified synthetic groundwater (0.42 M NaCl solution) by varying the control parameters temperature (25, 50, 70, 90 °C), solute oxygen (oxic/anoxic) and leaching time (1, 2, 4, 7 days). The influence of different control parameters and process interactions was analyzed by numerical simulations and statistics, using experimental data for parameterization and validation. The following results and implications for ATES operation in the originally oxygen-depleted aquifer were found for the potentially critical (contaminant/mineral-forming) mobile elements Al, As, Ba, Ca, Cu, Fe, Mn, Ni, Pb, and Si: The total leachable quantity of each element, i.e. the leached sum over all sequential extraction steps, is very small in the aquifer sandstone (〈0.1 mg/g), and significantly higher in the siltstone of the topset aquitard (up to ca. 4 mg/g for Ca). The iron system is the main risk factor. At oxic conditions, pyrite (FeS2) dissolves. If no suitable buffers are present, the solution is acidified, which facilitates the mobilization of several other elements. At anoxic conditions, the dissolution of iron hydroxides is the process mainly controlling element mobilization. Ferric iron re-precipitates readily, and is the main mineral-forming species in the investigated system. Calcium is predominantly adsorbed, and can be mobilized by pH reduction. In case the solute concentration decreases due to mineral precipitation, Ca can be desorbed quickly to regain thermodynamic equilibrium between rock matrix and groundwater. Small amounts of aluminum and silicon can be released rapidly from amorphous (hydr)oxides, which were their main source during leaching experiments of up to seven days. Kinetically slow dissolution of crystalline silicates prevails during longer leaching periods. Arsenic is nearly immobile in the aquifer sandstone. During the experiments, it was released only in the reduction step of the sequential extraction (ca. 0.02 µg/g), and represents no critical risk. Barium, copper, nickel, and lead have no single phase association. They are probably mainly present as solid solutions or co-precipitates, and their mobility seems to be primarily controlled by iron phase dissolution/precipitation. Copper was also found in elementary form. For the investigated heat storage at the German parliament buildings, these findings indicate no critical risk factors, which could lead to groundwater contamination or porosity reduction in dimensions that would prohibit ATES operation. However, constant nitrogen pressurization of the system is imperative to prevent oxygen intrusion, which could eventually lead to pyrite dissolution, groundwater acidification once its buffering capacity is exceeded, and critical element mobilization.
    Type: http://purl.org/eprint/type/Thesis
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  • 21
    Publication Date: 2019-02-01
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  • 22
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    In:  Proceedings Book | Cappadocia Earth Sciences Symposium#
    Publication Date: 2019-02-01
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  • 23
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    In:  Abstracts | 10th Cities on Volcanoes Conference#
    Publication Date: 2019-02-01
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  • 24
    Publication Date: 2019-02-01
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  • 25
    Publication Date: 2019-01-30
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  • 26
    Publication Date: 2019-02-01
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  • 27
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    In:  Proceedings | 43rd Workshop on Geothermal Reservoir Engineering#
    Publication Date: 2019-02-01
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  • 28
  • 29
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    In:  Programme and Abstract Book | 17th International Conference on the Properties of Water and Steam – ICPWS17#
    Publication Date: 2019-02-01
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  • 30
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    In:  Abstracts | 78th Society of Exploration Geophysicists International Exposition and Annual Meeting - SEG 2008#
    Publication Date: 2019-02-01
    Description: An analysis of two rock samples, hyaloclastites and basalts, at in-situ reservoir conditions has been done to identify the role of temperature on the seismic velocity and attenuation. The goal is to establish a temperature-dependent fluid substitution analysis of geothermal rocks using Gassmann equation within the framework of Biot's poroelasticity. The analysis of temperature-dependent wave attenuation is shown for hyaloclastites. The results show that the general decreasing trend of seismic velocity towards temperature may be related to the thermophysical characteristics of fluid. Using Gassmann equation it has been shown that the presence of steam bubbles can reduce the effective elastic property of rocks which indirectly demonstrates the role of temperature to the seismic velocity. The Q factor, i.e., inverse of attenuation, behaves surprisingly almost in the same way as the seismic velocity with temperature, except in the lower temperature range. The Q factor increase with the temperature is supposed to be a quick viscosity decrease. The later decrease of Q factor may indicate the presence of steam bubbles due to the further temperature increase. This finding demonstrates that the application of temperature-dependent fluid substitution modelling using Gassmann equation can be applied for the characterization of geothermal reservoir systems. Copyright © (2008) by the Society of Exploration Geophysicists All rights reserved.
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  • 31
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    In:  Geophysical Research Abstracts | General Assembly European Geosciences Union #
    Publication Date: 2019-02-01
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  • 32
    Publication Date: 2019-02-01
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  • 33
    Publication Date: 2019-02-01
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  • 34
    Publication Date: 2019-02-01
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  • 35
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    In:  Geophysical Research Abstracts | General Assembly European Geosciences Union #
    Publication Date: 2019-02-01
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  • 36
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    In:  Abstracts | II Pan-American Workshop on Geomagnetism - II Pangeo #
    Publication Date: 2019-02-01
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  • 37
    Publication Date: 2019-02-01
    Description: The SPHERES (Synchronized Position Hold Engage and Reorient Experimental Satellite) facility is a set of three free-flying satellites launched in 2006. In addition to scientists and engineers, middle- and high-school students program the SPHERES during the annual Zero Robotics programming competition. Zero Robotics conducts virtual competitions via simulator and on SPHERES aboard the ISS (International Space Station), with students doing the programming. A web interface allows teams to submit code, receive results, collaborate, and compete in simulator-based initial rounds and semi-final rounds. The final round of each competition is conducted with SPHERES aboard the ISS. At the end of 2017 a new robotic platform called Astrobee will launch, providing new game elements and new ground support for even more student interaction.
    Keywords: Cybernetics, Artificial Intelligence and Robotics; Astronautics (General)
    Type: ARC-E-DAA-TN33741 , International Space Station R&D Conference (ISSR&D 2016); 12-14 Jul. 2016; San Diego, CA; United States
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  • 38
    Publication Date: 2019-02-01
    Description: This document contains a list of human factors guidelines for remote pilot stations (RPS) arranged within an organizing structure. The guidelines are intended for the remote pilot stations (RPSs) of remotely piloted aircraft (RPA) that are capable of operating beyond visual line-of-sight in all airspace classes of the United States National Airspace System (NAS). Numerous human factors guidelines and standards for technological systems have been published by standards agencies and regulatory authorities. In compiling this document, the intent was not to reproduce or re-state existing human factors material. Instead, this document focuses on the unique issues of civilian RPAS, and contains guidelines specific to this sector. As a result, it should be seen as a supplement to existing aviation human factors standards and guidance material. Two constraints were used to focus the scope of this document. First, the assumptions contained in the FAA (2013a) UAS roadmap were used to define the responsibilities that will be assigned to the pilot of a RPAS operating beyond visual line-of-sight in the NAS. This in turn, helped to define the tasks that the remote pilot must perform via the RPS, and thereby the required features and characteristics of the RPS. Second, the points of difference between RPAS and conventional aviation were used to further focus the guidelines on the considerations that make piloting a RPA significantly different to piloting a conventional aircraft. Five broad categories of guidelines are identified. These are (1) performance-based descriptions of pilot tasks that must be accomplished via the RPS, (2) information content of displays, (3) descriptions of control inputs, (4) properties of the interface, and (5) high-level design considerations. Some of the guidelines in this document have been adapted from existing RPAS human factors material from several sources, including RTCA publications and Standardization Agreements (STANAGs) published by the North Atlantic Treaty Organization (NATO).
    Keywords: Aircraft Communications and Navigation
    Type: ARC-E-DAA-TN34128
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  • 39
    Publication Date: 2019-02-01
    Description: No abstract available
    Keywords: Administration and Management
    Type: JSC-E-DAA-TN57221 , Innovation Growth Lab (IGL) 2018 Global Conference; 12-14 Jun. 2018; Allston, MA; United States
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  • 40
    Publication Date: 2019-02-01
    Description: The analysis of observations of very high frequency radio noise intensity at the middle latitude on a frequency f = 500 MHz from 14th till 26th of October, 2003 is presented. These data are compared with the solar radio bursts in the range of frequencies 1-14 MHz registered by RAD2 receiver of the WAVES device installed on board the WIND spacecraft. The sporadic enhancement of near Earth very high frequency radio noise were observed with the help of ground radio telescope preferably either in pre mid night hours or at daytime. In many cases between October 17 and 22 short-term increases of the fluxes of low energy electrons, protons and ions in the interplanetary space by hundreds of times, corresponded to VHF radio bursts. At the same time slow increasing of solar cosmic rays streams at Lagrange point L1 and on geostationary orbit during October, 21 and 22, did not affect the usual radio noise level. A strong solar flare of 1B/X5.5 class on October 23 contributed to a prolonged rise of the intensity level of spectral radio emission, including the night sector of magnetosphere. It is assumed that very high frequency radio bursts in the near Earth space may appear when the processes of penetration of interplanetary low energy charge particles into Earth plasmasphere take place.
    Keywords: Geophysics
    Type: GSFC-E-DAA-TN9126 , Advances in Space Research (0273-1177; 1879-1948); 51; 3; 350-355
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  • 41
    Publication Date: 2019-02-01
    Description: An adjustably-autonomous intelligent systems approach for developing Closed Ecosystems (CESs) is presented, which includes a design concept and preliminary design details for the Controlled Closed-Ecosystem Development System (CCEDS) and the Orbiting Modular Artificial-Gravity Spacecraft (OMAGS). The paper is divided into three sections: CESs, the CCEDS Design Concept, and Orbiting Fractional-Gravity Closed Ecosystems OMAGS design concept. The first section briefly describes Closed EcoSystems (CESs), complex adaptive systems, biomes, microbial microbiomes, and their relevance for the study of astrobiology. This section also discusses initial efforts in the development of Closed Environment Life Support Systems (CELSSs) for sustainable communities in space and on Earth. This section concludes with a discussion of the bioregenerative life support system challenge of and the corresponding consequences due to the inverse relationship of the very small human biomass/non-human biomass ratio overall on the Earth with respect to the extremely large human biomass/non-human-biomass ratio found in cities and the International Space Station. The second section describes the CCEDS design concept, which consists of a population of controlled colonies of CES Modules (CESMs), each an integrated CES, continually generating data for an intelligent system that operates the CESs and their CESMs. A variety of CESM types and their use are briefly described. The CCEDS intelligent system uses an evolutionary computation algorithm described in this section to develop and optimize these CESs to increase their viability duration and the size of the animals they support with the ultimate goal to support populations of humans, both on Earth and in space. The CCEDS architecture, its five control subsystems, and its five evolutionary computation levels are also discussed. The section concludes with a discussion of several CCEDS design strategies. The third section summarizes the OMAGS design concept for a spacecraft with a payload consisting of CESs in an orbiting spacecraft centrifuge that operates for at least 5 years. The spacecraft concept is described including its 150cm-radius centrifuge with a 2 ton & 3,000 liter bioscience payload capacity for 24 CESMs. The centrifuge design has four physical levels for its CESMs, each level subject to a different fractional gravity level. This section presents the spacecraft benefits of being designed and operated such that the spacecraft and payload centrifuge wheel counter-rotate resulting in net zero angular momentum and zero gyroscopic forces. Artificial-gravity generation by centripetal acceleration is also discussed. This section concludes by showing the external specifications of the CESMs and their layout in the centrifuge, followed by discussing the multi-payload module rationale. In tandem, the CCEDS and OMAGS systems can be used to foster gravitational ecosystem research for developing sustainable communities in space and on Earth.
    Keywords: Man/System Technology and Life Support; Cybernetics, Artificial Intelligence and Robotics
    Type: NASA/TM-2018–56787
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  • 42
    Publication Date: 2019-02-01
    Description: We show here that none of the concerns of Yuter et al. [2013, hereinafter Y2013] have any validity. We use this opportunity to clarify issues that may have been misunderstood by some readers (Y2013 among them) of Rosenfeld and Bell [2011, hereinafter RB2011], elaborate on our explanations there and further substantiate the evidence showing the impacts of aerosols on severe convective storms and the ways by which they are manifested in the weekly cycle. [2] Y2013 raise two general questions concerning the evidence for a weekly cycle of tornadoes given by RB2011: (1) whether the statistical analysis is valid, and (2) whether the discussion of physical mechanisms that explain the weekly cycle is correct. [3] In section 2, we show that there is no basis for the criticisms of Y2013 concerning the physical mechanisms proposed in RB2011 behind the observed changes in tornado activity and show further the mechanism by which aerosols can modulate tornadoes. Most of the comments by Y2013 appear to result from a misunderstanding and misinterpretation of RB2011. In section 3, we show that the comments by Y2013 concerning the statistical analysis are either incorrect or irrelevant. Some of the questions they raised were already answered previously by RB2011, and references therein. We also show that the complaint of Y2013, that the spatial averaging used in RB2011 inappropriately blends tornado behavior of different kinds in different regions, is unfounded.
    Keywords: Meteorology and Climatology
    Type: GSFC-E-DAA-TN9641 , Journal of Geophysical Research: Atmospheres (2169-897X; 2169-8996); 118; 13; 7339-7343
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  • 43
    Publication Date: 2019-02-01
    Description: Only a handful of supernovae (SNe) have been studied in multiwavelengths from the radio to X-rays, starting a few days after the explosion. The early detection and classification of the nearby Type IIb SN 2011dh/PTF 11eon in M51 provides a unique opportunity to conduct such observations. We present detailed data obtained at one of the youngest phase ever of a core-collapse SN (days 3-12 after the explosion) in the radio, millimetre and X-rays; when combined with optical data, this allows us to explore the early evolution of the SN blast wave and its surroundings. Our analysis shows that the expanding SN shock wave does not exhibit equipartition (epsilon(sub e)/epsilon(sub B) approx. 1000), and is expanding into circumstellar material that is consistent with a density profile falling like R(exp 2). Within modelling uncertainties we find an average velocity of the fast parts of the ejecta of 15 000 +/- 1800 km/s, contrary to previous analysis. This velocity places SN 2011dh in an intermediate blast wave regime between the previously defined compact and extended SN Type IIb subtypes. Our results highlight the importance of early (approx.1 d) high-frequency observations of future events. Moreover, we show the importance of combined radio/X-ray observations for determining the microphysics ratio epsilon(sub e)/epsilon(sub B).
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN12189 , Monthly Notices of the Royal Astronomical Society (0035-8711; 1365-2966); 436; 2; 1258-1267
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  • 44
    Publication Date: 2019-02-01
    Description: Ozone profiles from balloon-borne ozonesondes are used for development of satellite algorithms and in chemistry-climate model initialization, assimilation and evaluation. An important issue in the application of these profiles is how best to treat variations where varying photochemical and dynamical influences can cause the ozone mixing ratio in the tropospheric segments of the profile to change by of a factor of 2-3 within a day. Clustering techniques are an ideal way to approach the statistical classification of profile data and we apply self-organizing maps to tropical tropospheric SHADOZ data, hypothesizing that the data will sort according to various influences on ozone, namely anthropogenic sources like biomass burning, meteorological conditions, and stratospheric or extra-tropical intrusions. Self-organizing maps, that use a learning algorithm to reveal the most prominent features of a data set according to a specified number of clusters, have been determined for the 1998-2009 SHADOZ profiles over Ascension Island (512 profiles, 7.98 deg. S, 14.42 deg. W) and Natal, Brazil (425 profiles, 5.42degS, 35.38degW). The 2 2 self-organizing map, which creates 4 clusters, reveals that deviations from the average ozone in the free troposphere include both increased ozone resulting from seasonal biomass burning in Africa and locally reduced ozone brought about by convective lifting of unpolluted boundary-layer air. Expanding to a 4 4 self-organizing map shows how biomass burning influences the yearly cycle of tropospheric ozone at Ascension Island and captures the seasonality of ozone at both Ascension Island and Natal. Comparing Ascension Island and Natal using a 4 4 self-organizing map at each site reveals similarities in mid-tropospheric ozone, but shows differences in lower-tropospheric ozone due to Ascension Island being closer to African biomass burning and more affected by descent from the mean Walker circulation, with less convective activity, than Natal.
    Keywords: Meteorology and Climatology; Environment Pollution
    Type: GSFC-E-DAA-TN9774 , Journal of Geophysical Research: Atmospheres (2169-897X; 2169-8996); 117; D4; D04302
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  • 45
    Publication Date: 2019-02-01
    Description: Pseudospectral (PS) methods possess a number of characteristics (e.g., efficiency, accuracy, natural boundary conditions) that are extremely desirable for dynamo models. Unfortunately, dynamo models based upon PS methods face a number of daunting challenges, which include exposing additional parallelism, leveraging hardware accelerators, exploiting hybrid parallelism, and improving the scalability of global memory transposes. Although these issues are a concern for most models, solutions for PS methods tend to require far more pervasive changes to underlying data and control structures. Further, improvements in performance in one model are difficult to transfer to other models, resulting in significant duplication of effort across the research community.We have developed an extensible software framework for pseudospectral methods called SpF that is intended to enable extreme scalability and optimal performance. High-level abstractions provided by SpF unburden applications of the responsibility of managing domain decomposition and load balance while reducing the changes in code required to adapt to new computing architectures. The key design concept in SpF is that each phase of the numerical calculation is partitioned into disjoint numerical kernels that can be performed entirely in-processor. The granularity of domain-decomposition provided by SpF is only constrained by the data-locality requirements of these kernels. SpF builds on top of optimized vendor libraries for common numerical operations such as transforms, matrix solvers, etc., but can also be configured to use open source alternatives for portability. SpF includes several alternative schemes for global data redistribution and is expected to serve as an ideal testbed for further research into optimal approaches for different network architectures.In this presentation, we will describe the basic architecture of SpF as well as preliminary performance data and experience with adapting legacy dynamo codes. We will conclude with a discussion of planned extensions to SpF that will provide pseudospectral applications with additional flexibility with regard to time integration, linear solvers, and discretization in the radial direction.
    Keywords: Computer Programming and Software
    Type: GSFC-E-DAA-TN11913 , GP51A-1072 , AGU Fall Meeting; 9-13 Dec. 2013; San Francisco, CA; United States
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  • 46
    Publication Date: 2019-02-01
    Description: A brief review is presented of the Transfer Function Model (TFM) [e.g., Mayr et al., Space Science Reviews, 1990], which describes acoustic gravity waves (AGW) that propagate across the globe in a dissipative and static (no winds) background atmosphere with globally uniform temperature and density variations extending from the ground to 700 km. Unique among existing models, the TFM can be placed between the analytical approach on one end, and the rigorous numerical approach of general circulation models (GCM). The time consuming numerical integration of the conservation equations is restricted to compute the transfer function (TF) for a broad range of frequencies and spherical harmonics. Given TF, the atmospheric response for a chosen source configuration is then obtained in short order. Computationally efficient, the model is well suited to serve as experimental and educational tool for simulating propagating wave patterns across the globe. By design, the TFM is also semi-analytical and therefore well suited to explore the different wave modes that can be generated under different dynamical conditions.
    Keywords: Geophysics
    Type: GSFC-E-DAA-TN9701 , Journal of Atmospheric and Solar-Terrestrial Physics (1364-6826); 104; 7-17
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  • 47
    Publication Date: 2019-02-01
    Description: We present diffraction-limited K s band and L(prime) adaptive optics images of the edge-on debris disk around the nearby F2 star HD 15115, obtained with a single 8.4 m primary mirror at the Large Binocular Telescope. At the Ks band, the disk is detected at signal-to-noise per resolution element (SNRE) approx. 3-8 from approx. 1 to 2".5 (45-113 AU) on the western side and from approx. 1". 2 to 2".1 (63-90 AU) on the east. At L the disk is detected at SNRE approx. 2.5 from approx. 1 to 1".45 (45-90 AU) on both sides, implying more symmetric disk structure at 3.8 micrometers. At both wavelengths the disk has a bow-like shape and is offset from the star to the north by a few AU. A surface brightness asymmetry exists between the two sides of the disk at the Ks band, but not at L(prime). The surface brightness at the K s band declines inside 1"(approx. 45 AU), which may be indicative of a gap in the disk near 1".The K s L(prime) disk color, after removal of the stellar color, is mostly gray for both sides of the disk. This suggests that scattered light is coming from large dust grains, with 3-10 micrometers sized grains on the east side and 1-10 micrometers dust grains on the west. This may suggest that the west side is composed of smaller dust grains than the east side, which would support the interpretation that the disk is being dynamically affected by interactions with the local interstellar medium.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN9545 , Astrophysical Journal (0004-637X; 1538-4357); 752; 1; 57
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  • 48
    Publication Date: 2019-02-01
    Description: We reconstruct the gravitational lensing convergence signal from Cosmic Microwave Background (CMB) polarization data taken by the Polarbear experiment and cross-correlate it with Cosmic Infrared Background (CIB) maps from the Herschel satellite. From the cross-spectra, we obtain evidence for gravitational lensing of the CMB polarization at a statistical significance of 4.0sigma and evidence for the presence of a lensing B-mode signal at a significance of 2.3sigma. We demonstrate that our results are not biased by instrumental and astrophysical systematic errors by performing null-tests, checks with simulated and real data, and analytical calculations. This measurement of polarization lensing, made via the robust cross-correlation channel, not only reinforces Polarbear auto-correlation measurements, but also represents one of the early steps towards establishing CMB polarization lensing as a powerful new probe of cosmology and astrophysics.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN15348 , Physical Review Letters (0031-9007; 1079-7114); 112; 13; 131302
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  • 49
    Publication Date: 2019-02-01
    Description: An experimental investigation has been made to determine the hydro-dynamic characteristics of a 10-percent-thick hydrofoil with an aspect ratio of 3 designed to operate with acceptable efficiency at speeds in the neighborhood of 100 knots (169 fps). A cambered hydrofoil model with parabolic thickness distribution was investigated at a depth of chord over a range of angles of attack from -0.5 deg to 4.0 deg and at speeds from 120 to 210 fps. substantially wider range of operation at acceptable lift-drag ratios as well as higher maximum lift-drag-ratio values than did a hydrofoil of similar design with an aspect ratio of 1.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NASA-TN-D-728 , L-1358
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  • 50
    Publication Date: 2019-02-01
    Description: The application of forces in multi-body dynamical environments to permit the transfer of spacecraft from Earth orbit to Sun-Earth weak stability regions and then return to the Earth-Moon libration (L1 and L2) orbits has been successfully accomplished for the first time. This demonstrated that transfer is a positive step in the realization of a design process that can be used to transfer spacecraft with minimal Delta-V expenditures. Initialized using gravity assists to overcome fuel constraints; the ARTEMIS trajectory design has successfully placed two spacecrafts into Earth-Moon libration orbits by means of these applications.
    Keywords: Astrodynamics
    Type: GSFC-E-DAA-TN15167 , Acta Astronautica (0094-5765); 73; 237-249
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  • 51
    Publication Date: 2019-02-01
    Description: The tumbling motion of vehicles entering planetary atmospheres is analyzed. A differential equation governing the tumbling motion, its arrest, and the subsequent oscillatory motion is obtained and identified as the equation for the fifth Painleve transcendant. An approximate analytical solution for the transcendant is derived. Comparisons with results obtained from numerical integration of the exact equations of motion indicate that the solution for the angle-of-attack history is sufficiently accurate to be of practical use.
    Keywords: Astrodynamics; Aerodynamics
    Type: A-661 , NASA-TN-D-1549
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  • 52
    Publication Date: 2019-02-01
    Description: A liquid propellant mass measurement system is proposed for the zero gravity environment. The known thermodynamic relationships for the liquid propellant and helium gas concomitant with state of the art instrumentation are used to provide a system comparable with present day terrestrial mass measuring systems. In particular, the operation of the system is outlined for the propellant transfer method and for the determination of leaks and leakage rates. A second concept which is a simplified version of the proposed mass measurement system is introduced and discussed.
    Keywords: Propellants and Fuels
    Type: NASA-TN-D-1571
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  • 53
    Publication Date: 2019-02-01
    Description: A method for determining shock-wave shapes, stagnation-point location, and flow-field properties for spherically blunt bodies at angle of attack was developed. The method is applicable to perfect gas flows and equilibrium flow of real gases. The results given by the method for shock surface and stagnation-point location are compared with experimental values. Comparison of the shock-layer density and temperature distribution are also made between the results of the method and those of a more exact procedure for a sphere. These comparisons indicate satisfactory agreement.
    Keywords: Fluid Mechanics and Thermodynamics; Aerodynamics
    Type: NASA-TN-D-1423 , A-596
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  • 54
    Publication Date: 2019-02-01
    Description: The thermodynamic properties, density and temperature, as well as transport property parameters involving viscosity, Prandtl number (including diffusion effects), and gaseous radiation absorption coefficients have been correlated as a function of enthalpy at four pressure levels (10 (sup -1), 10 (sup 0), 10, and 10 (sup 2) atmospheres). The correlation formulas are written in a generalized form for which coefficients for a particular property and pressure level are tabulated. The correlation formulas are useful in digital computer programs for non-adiabatic viscous flow problems.
    Keywords: Fluid Mechanics and Thermodynamics; Aerodynamics
    Type: NASA-TN-D-1429 , A-664
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  • 55
    Publication Date: 2019-02-01
    Description: Closed-form solutions of the one-dimensional heat-conduction equations for the flow of heat into a plate with a laminar boundary layer have been obtained for a configuration entering a planetary atmosphere with constant velocity and negative entry angle. The atmospheric density was assumed to obey an exponential law and the temperature was assumed constant initially. The solution is in the form of a Fourier series expansion which, for most practical applications, can be approximated by retaining only one term of the expression. The solution applies to the initial part of the entry before the maximum heating conditions are encountered.
    Keywords: Aerodynamics; Astrodynamics
    Type: NASA-TN-D-1476 , L-2029
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  • 56
    Publication Date: 2019-02-01
    Description: A Monte Carlo code simulating neutron transport in infinite cones of water and water-equivalent hydrogen was prepared for an IBM 704 computer. The code was essentially a modification of the point-source, infinite-medium code used in NASA TN D-850. Studies were made of differential neutron number spectra and associated buildup factors for infinite cones having apex half-angles of 15 degrees, 30 degrees, 45 degrees, and 60 degrees. The buildup factors obtained were compared with those for the appropriate infinite medium, which allowed an examination of the effect of solid angle subtended by material on the transport of 6-Mev source neutrons emanating from the cone apex. The variation of number buildup factor with distance for the various cones shows that neutron scattering out of the cones is predominant in the first 30 t o 40 centimeters of material, and that transport beyond this distance is of a similar nature in all the cones.
    Keywords: Space Radiation
    Type: NASA-TN-D-1434 , E-1584
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  • 57
    Publication Date: 2019-02-01
    Description: An investigation was made of some aspects of erectable umbrella-type paraboloidal solar-energy concentrators for use in spacecraft auxiliary power systems. An analysis is presented for the design of concentrators employing radial ribs and membrane-type coverings. The rib stiffness necessary to give a desired parabolic curvature upon erection is determined. Rib contour measurements were made in an upright and inverted position on an experimental 10-foot-diameter concentrator giving a focal length of 30.78 inches and 30.6 inches, respectively, as compared with a design focal length of 30 inches. Calorimetric tests employing spherical heat receivers showed a maximum geometrical concentrator efficiency of 75.3 percent with a concentration ratio of 92.2 at a focal length of approximately 30.5 inches. Within the scope of this investigation, it was found that, as the concentrator size increases, the weight per unit projected area increases, time to damp to one-half amplitude increases, and the natural frequency decreases. Umbrella-type solar concentrators appear to be feasible for power conversion systems using low concentration ratios; however, for large concentrators the time required to damp out disturbances may be a problem.
    Keywords: Communications and Radar
    Type: NASA-TN-D-1368 , L-1945
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  • 58
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    Schweizerbart
    In:  Meteorologische Zeitschrift, 18 (4). pp. 433-443.
    Publication Date: 2019-01-31
    Description: The internal and external North Atlantic Sector variability is investigated by means of a multimillennial control run and forced experiments with the Kiel Climate Model (KCM). The internal variability is studied by analyzing the control run. The externally forced variability is investigated in a run with periodic millennial solar forcing and in greenhouse warming experiments with enhanced carbon dioxide concentrations. The surface air temperature (SAT) averaged over the Northern Hemisphere simulated in the control run displays enhanced variability relative to the red background at decadal, centennial, and millennial timescales. Special emphasis is given to the variability of the Meridional Overturning Circulation (MOC). The MOC plays an important role in the generation of internal climate modes. Furthermore, the MOC provides a strong negative feedback on the Northern Hemisphere SAT in both the solar and greenhouse warming experiments, thereby moderating the direct effects of the external forcing in the North Atlantic. The implications of the results for decadal predictability are discussed.
    Type: Article , PeerReviewed
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  • 59
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    In:  (Doctoral thesis/PhD), Christian-Albrechts-Universität Kiel, Kiel, Germany, 118 pp . Berichte aus dem Sonderforschungsbereich 313, Veränderungen der Umwelt - Der Nördliche Nordatlantik, 49 .
    Publication Date: 2019-01-31
    Type: Thesis , NonPeerReviewed
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  • 60
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    United Nations Environment Programme
    In:  The adaptation gap report 2018
    Publication Date: 2019-01-31
    Language: English
    Type: http://purl.org/eprint/type/BookItem
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  • 61
    Publication Date: 2019-01-31
    Language: English
    Type: http://purl.org/escidoc/metadata/ves/publication-types/article
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  • 62
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    In:  CASI
    Publication Date: 2019-01-31
    Description: Space simulations including thermal vacuum, atomic oxygen, and ultraviolet radiation were performed to study the durability of various additively manufactured materials. In addition to ground simulations, additively manufactured materials were selected for a one-year flight on the Materials on International Space Station Experiment (MISSE) Flight Facility. The space environment is composed of atomic oxygen, ultraviolet radiation, protons, electrons, meteoroid/space debris impacts, thermal cycling, and hard vacuum. An improved UV sensor is also discussed.
    Keywords: Space Processing
    Type: M-1473 , M18-6856 , NASA/TP-2018-220123
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  • 63
    Publication Date: 2019-01-31
    Description: The International Space Station is a unique laboratory for performing investigations that affect human health both in space and on Earth. During its time in orbit, the space station has enabled research that is providing a better understanding of many aspects of human health including aging, trauma, disease and environmental impacts. Driven by the need to support astronaut health, several biological and human physiological investigations have yielded important results that we on Earth can also benefit from. These results include new ways to mitigate bone loss, insights into bacterial behavior, and innovative wound-healing techniques. Advances in telemedicine, disease models, psychological stress response systems, nutrition and cell behavior are just a few more examples of the benefits that have been gained from applying studies in orbit to human health back on Earth.
    Keywords: Aerospace Medicine
    Type: JSC-E-DAA-TN58554 , Expo-Ciencias Latinoamericana ESI AMLAT 2018; 2-6 Jul. 2018; Antofagasta; Chile
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  • 64
    Publication Date: 2019-01-31
    Description: The use of solid iodine as a propellant in Hall-effect thrusters (HETs) is currently being investigated for small-satellite applications. CubeSats offer an inexpensive mode of access to space; however, they currently lack significant propulsion capability. A high specific impulse (I (sub sp)) propulsion system would permit a significant change in velocity, delta v, to be imparted for orbital maintenance, transfers, or de-orbit maneuvers. An electric propulsion system that uses iodine as a propellant has a number of advantages. It has an exceptionally high rho times I (sub sp) figure of merit (density multiplied by the specific impulse), meaning that it can achieve a large total delta v with a relatively low combination of propellant mass and propellant tank volume. Also, the propellant feed system operates at low pressures (a few psia at most), as opposed to the use of super-critical xenon stored at very high pressure. Low pressure operation can lower system mass while greatly reducing the risk of propellant tank rupture, making low pressure a vitally important property for propellants on secondary payloads like CubeSats, where risks must be minimized. The iSAT mission aims to demonstrate iodine-fed HET technology, flying it in space onboard a 12U 912-unit) CubeSat. In the iSAT propellant feed system (PFS), solid iodine is sublimed through heating to produce gaseous propellant that is conducted through tubing to the thruster and cathode. The sublimation process is governed by the iodine (I2) vapor pressure, which is shown as a function of temperature in figure 1. As gaseous I2 flows out of the tank, the gas pressure in the volume containing the solid iodine propellant is reduced until a balance between the flow of iodine out of the tank and the sublimation rate of solid iodine at the equilibrium gas pressure and chosen tank temperature is reached.
    Keywords: Propellants and Fuels
    Type: M18-6867 , M-1474 , NASA/TM-2018-220124
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  • 65
    Publication Date: 2019-01-31
    Description: Next-generation space missions are constrained by existing spacecraft navigation systems which are not fully autonomous. These systems suffer from accumulated dead-reckoning errors and must therefore rely on periodic updates provided by supplementary technologies that depend on line-of-sight signals from Earth, satellites, or other celestial bodies (e.g., GPS, star-trackers) for absolute attitude and position determination, which can be spoofed, incorrectly identified, occluded, obscured, attenuated, or insufficiently available. These dead-reckoning errors originate in the accelerometers and ring laser gyros (RLGs) themselves, which constitute inertial measurement units (IMUs). Increasing the time for standalone spacecraft navigation therefore requires fundamental improvements in the precision of inertial sensors. The conventional method of increasing the precision of an optical gyro is to increase its size, but this is problematic in spaceflight where size and weight are at a premium. One promising solution to enhance gyro precision without increasing size is to place an anomalous dispersion or fast-light (FL) material inside the gyro cavity. The FL essentially provides a positive feedback to the gyro response, resulting in a larger measured beat frequency for a given rotation rate as shown in figure 1.
    Keywords: Space Communications, Spacecraft Communications, Command and Tracking; Instrumentation and Photography
    Type: M18-6944 , M-1472 , NASA/TM-2018-219867
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  • 66
    Publication Date: 2019-01-31
    Description: As part of a program examining a composite payload adaptor fitting (PAF) for NASAs Space Launch System (SLS), a repair study of impact damage and misdrilled holes was undertaken. At the beginning of this repair study, the PAF was baselined as a honeycomb sandwich structure with eight-ply quasi-isotropic, carbon-fiber-reinforced epoxy facesheets. Although the baseline configuration could change, the repair program presented herein is generic enough in nature such that it will apply to most sandwich configurations. The vast majority of loads experienced by this structure will be in-plane compression; thus, this repair study concentrates on the in-plane compression strength of representative sandwich structure specimens. The PAF is a truncated cone with a minimum diameter of about 170 inches at the top and a maximum diameter of about 335 inches at the bottom. While the launch vehicle hardware should be protected throughout its life on the ground, rogue events (or misdrilled holes) are still a possibility. This study is not meant to address large scale damage or damage to the part other than in the acreage (the uniform portion of the structure that does not consist of joints or other detailed areas), but address the most probable type of damages (small impacts and misdrilled holes) in the vast majority of the structure (the acreage).
    Keywords: Composite Materials; Structural Mechanics
    Type: M-1470 , NASA/TM-2018-219866 , M18-6927
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  • 67
    Publication Date: 2019-01-31
    Description: The initial objective of this study was to evaluate the effect of an extended delay time between preweld cleaning and the completion of a self-reacting friction stir welding (SRFSW) process on the resulting quality of various thickness panels of AA2219-T87. The current NASA standard specifies no more than a 48 hour delay between preweld cleaning and actual welding. The concern is whether increasing the cleaning delay time results in development of the residual oxide defect (ROD) in SRFSW. This concern emanates from the possibility of increased time correlating with increased oxide layer thickness on the faying surfaces. Oxide content on the faying surfaces has been reported to correlate with the occurrence of the ROD which reduces mechanical properties. When the SRFSW process was first adopted by the NASA Marshall Space Flight Center (MSFC), unexpected low tensile values that resulted were attributed to oxides within the weld that appeared to follow the former faying surface contours. Mitigation of the ROD was achieved through a combination of modifications to the processing parameters, tool designs, and incorporation of a weld seam offset. Two operations are involved in preweld cleaning: the first is removal of oil and grease, and the second is removal of surface oxides. In arc welding, improper cleaning of the faying surfaces of aluminum welded joints can increase the sensitivity toward development of defects. As the aluminum is locally melted, these contaminants contribute toward the development of porosity, inclusions, entrapped oxides, and other discontinuities which can degrade the strength of the weld joint. For weldment of large structures, the weld joint is typically cleaned, fit-up, and tack welded prior to the final full penetration welding pass. Because of the stringent joint fit-up requirements for mismatch and peaking for launch vehicle structures, the joint fit-up can sometimes contribute to lengthy delays between cleaning and tack welding, especially for circumferential weld joints on large diameter components. When the conventional friction stir welding (CFSW) process was introduced at the NASA MSFC, there was no procedure for cleaning prior to the solid-state joining process. As the process expanded to include SRFSW, preparation of the faying, crown, and root surfaces were implemented to overcome the ROD. Although the solid-state process is not expected to reach temperatures high enough for dissociation of the native oxide layer, concern remained regarding the redeposition of the native oxide layer within the stir zone. NASA has previously established the allowable time at 48 hours between preweld cleaning and a SRFSW process. The effect of potential 2 contamination resulting from an extended delay to 188 hours was subsequently evaluated for SRFSWs using tensile testing and metallographic imaging. Tensile specimens were tested at room temperature (RT), and at cryogenic conditions of liquid nitrogen (LN2) and liquid hydrogen. No detrimental effect on weld quality, as determined by weld strength, was reported for cleaning delays of 48, 120, 168, 240 or 288 hours. While no trends were established in this study, which extended the delay from 48 to 188 hours, there were a few outliers in terms of ultimate tensile strength (UTS). According to M. Fisher's 2014 Boeing Company Memo no. EYBF-MAF-14-029, all outliers were above the minimum acceptance criteria, but out of family with respect to the average values. As the robustness and reliability of any process ultimately depends on the average values as well as the outliers, an understanding of the cause of these outliers will ultimately improve the process. This report examines those outliers and their possible causes.
    Keywords: Mechanical Engineering
    Type: NASA/TM-2018-219863 , M18-6889 , M-1467
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  • 68
    Publication Date: 2019-01-31
    Description: The NASA Green Propulsion Working Group (GPWG) was tasked by the NASA Chemical Propulsion Subcapabilities Management (CPSM) with the development of this NASA Green Propulsion Technologies Development Roadmap, herein referred to as the Green Propulsion Roadmap, or simply the Roadmap, to provide guidance to NASA through the CPSM on green propulsion technology development. Other agencies or commercial partners may refer to this roadmap as well. It is envisioned that the synthesis of various Center-based activities and knowledge repositories will result in a cumulative knowledge gain, and will provide capabilities beyond the sum contribution of individual Centers. Ultimately, a well-defined roadmap of technology investment path, the enhanced coordination and alignment of activities among NASA Centers and other Federal Agencies, and a well-supported green propulsion community will facilitate the path towards the broader infusion of green propulsion technologies for science and human exploration missions, as well as a deeper understanding of the fundamental behaviors and characteristics of these systems that is on par with other historically used monopropellant propulsion systems, such as hydrazine.
    Keywords: Spacecraft Propulsion and Power
    Type: M18-6783 , M-1465 , NASA/TP-2018-219861
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  • 69
    Publication Date: 2019-01-31
    Description: We propose a novel Bayesian Monte Carlo Integration (BMCI) technique to retrieve the profiles of temperature, water vapor, and cloud liquid/ice water content from microwave cloudy measurements in the presence of TCs. These retrievals then can either be directly used by meteorologists to analyze the structure of TCs or be assimilated to provide accurate initial conditions for the NWP models. The technique is applied to the data from the Advanced Technology Microwave Sounder (ATMS) onboard Suomi National Polar-orbiting Partnership (NPP) and Global Precipitation Measurement (GPM) Microwave Imager (GMI).
    Keywords: Meteorology and Climatology
    Type: GSFC-E-DAA-TN50544 , AGU Fall Meeting; 11-15 Dec. 2017; New Orleans, LA; United States
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  • 70
    Publication Date: 2019-01-31
    Description: Statistical techniques permit the retrieval of soil moisture estimates in a model climatology while retaining the spatial and temporal signatures of the satellite observations. As a consequence, the need for bias correction prior to an assimilation of these estimates is reduced, which could result in a more effective use of the independent information provided by the satellite observations. In this study, a statistical neural network (NN) retrieval algorithm is calibrated using SMAP brightness temperature observations and modeled soil moisture estimates (similar to those used to calibrate the SMAP Level 4 DA system). Daily values of surface soil moisture are estimated using the NN and then assimilated into the NASA Catchment model. The skill of the assimilation estimates is assessed based on a comprehensive comparison to in situ measurements from the SMAP core and sparse network sites as well as the International Soil Moisture Network. The NN retrieval assimilation is found to significantly improve the model skill, particularly in areas where the model does not represent processes related to agricultural practices. Additionally, the NN method is compared to assimilation experiments using traditional bias correction techniques. The NN retrieval assimilation is found to more effectively use the independent information provided by SMAP resulting in larger model skill improvements than assimilation experiments using traditional bias correction techniques.
    Keywords: Earth Resources and Remote Sensing
    Type: GSFC-E-DAA-TN50552 , Annual American Geophysical Union (AGU) Fall Meeting 2017 ; 11-15 Dec. 2017; New Orleans, LA; United States
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  • 71
    Publication Date: 2019-01-31
    Description: Extreme monsoon rainfall in India has disastrous consequences, including significant socio- economic impacts. However, little is known about the overall trends and climate factors associated with extreme rainfall because rainfall greatly varies across India and because few appropriate methods are available to measure extreme rainfall in the context of such heterogeneity. To provide a comprehensive assessment of extreme monsoon rainfall, we developed a metric using record rainfall data to measure the changes in the likelihood of extreme high and extreme low rainfall over time; this metric is independent of the characteristics of the underlying rainfall distributions. Hence, the metric is ideally suited to aggregate extreme rainfall information across heterogeneous regions covering India. We found that from 1930 to 2013, the likelihood of extreme high and extreme low rainfall increases 2-fold and 4-fold, respectively. These overall trend increases are driven by anomalous increases, particularly in the early 2000s; the likelihood of extreme high and extreme low rainfall increases 5-fold and 18-fold in 2005 and 2002, respectively. These findings imply a broadening of the underlying monsoon rainfall distribution over the past century. We also show that the time patterns of the likelihood of extreme rainfall in recent decades are correlated with the El Nino Southern Oscillation, Indian Ocean Dipole, and surface air temperature in the Northern Hemisphere.
    Keywords: Meteorology and Climatology
    Type: GSFC-E-DAA-TN21008 , Journal of Climate (0894-8755; 1520-0442); 28; 7; 2842-2855
    Format: text
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  • 72
    Publication Date: 2019-01-31
    Description: The atmospheric general circulation model (GCM) that underlies the MERRA-2 reanalysis includes a suite of physical parameterizations that describe the processes that occur in the planetary boundary layer (PBL). The data assimilation system assures that the atmospheric state variables used as input to these parameterizations are constrained to the best fit to all of the available observations. Many studies, however, have shown that the GCM-based estimates of MERRA-2 PBL heights are biased high, and so are not reliable for application related to constituent transport or the carbon cycle. A new 20-year record of PBL heights was derived from Wind Profiler (WP) backscatter data measured at a wide network of stations throughout the US Great Plains and has been validated against independent estimates. The behavior of these PBL heights shows geographical and temporal variations that are difficult to attribute to particular physical processes without additional information that are not part of the observational record. In the present study, we use information on physical processes from MERRA-2 to understand the behavior of the WP derived PBL heights. The behavior of the annual cycle of both MERRA-2 and WP PBL heights shows three classes of behavior: (i) canonical, where the annual cycle follows the annual cycle of the sun, (ii) delayed, where the PBL height reaches its annual maximum after the annual maximum of the solar insolation, and (iii) double maxima, where the PBL height begins to rise with the solar insolation but falls sometimes during the summer and then rises again. Although the magnitude of these types of variations is described by the WP PBL record, the explanation for these behaviors and the relationship to local precipitation, temperature, hydrology and sensible and latent heat fluxes is articulated using information from MERRA-2.
    Keywords: Geophysics
    Type: GSFC-E-DAA-TN50616 , American Geophysical Union (AGU) 2017 Fall Meeting; 11-15 Dec. 2017; New Orleans, LA; United States
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  • 73
    Publication Date: 2019-01-31
    Description: Key points discussed in this chapter are (1) the importance of aurora research to scientific advances and space weather applications, (2) space weather products at CCMC that are relevant to aurora monitoring and forecasting, and (3) the need for more effort from the whole community to achieve a better and long-lead- time forecast of auroral activity. Aurora, as manifestations of solar wind-magnetosphere-ionosphere coupling that occurs in a region of space that is relatively easy to access for sounding rockets, satellites, and other types of observational platforms, serves as a natural laboratory for studying the underlying physics of the complex system. From a space weather application perspective, auroras can cause surface charging of technological assets passing through the region, result in scintillation effects affecting communication and navigation, and cause radar cluttering that hinders military and civilian applications. Indirectly, an aurora and its currents can induce geomagnetically induced currents (GIC) on the ground, which poses major concerns for the wellbeing and operation of power grids, particularly during periods of intense geomagnetic activity. In addition, accurate auroral forecasting is desired for auroral tourism. In this chapter, we first review some of the existing auroral models and discuss past validation efforts. Such efforts are crucial in transitioning a model(s) from research to operations and for further model improvement and development that also benefits scientific endeavors. Then we will focus on products and tools that are used for auroral monitoring and forecasting at the Space Weather Research Center (SWRC). As part of the CCMC (Community Coordinated Modeling Center), SWRC has been providing space weather services since 2010.
    Keywords: Geophysics
    Type: GSFC-E-DAA-TN50072 , Auroral Dynamics and Space Weather; 291-301
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  • 74
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    Physika-Verlag, Würzburg
    In:  Herausgeberexemplar (Archiv der DGG in Leipzig) | 8 Z NAT 2148
    Publication Date: 2019-01-26
    Description: Inhaltsverzeichnis : Übersichtsartikel: EIDEN, R. und G. ESCHELBACH: Das atmosphärische Aerosol und seine Bedeutung für den Energiehaushalt der Atmosphäre . . . 189 ; MÜLLER, G.: Theoretical Body Wave Seismograms for Media with Spherical Symmetry — Discussion and Comparison of Approximate Methods . . . 229 ; SCHICK, R., and M. RIUSCETTI: An Analysis of Volcanic Tremors at South Italian Volcanoes . . . 247 ; FRÖHLICH, R. K.: Combined Magnetic and Geoelectrical Investigations over Lava Flows in the Volcanic Zone of the Laacher See, West Germany . . . 263 ; MAKRIS, J., J. ZIMMERMANN, H. C. BACHEM, and B. RITTER: Gravity Survey of South AFAR, Ethiopia . . . 279 ; BRÜCKL, E., und W. FÜRLINGER: Ein Vergleich von geologischen Gefügeaufnahmen mit seismischen Messungen . . . 291 ; As, J. A.: The Compensation Method for Measuring the Components of the Earth’s Magnetic Field . . . 303 ; Briefe an den Herausgeber: FUCHS, K.: The Fine Structure of the Lower Lithosphere — a Possible Marker for its Vertical Deformation . . . 313 ; LAUDATIO zur Verleihung der Emil-Wiechert-Medaille an Prof. Dr. LUDWIG BIERMANN . . . 317 ; In memoriom GÜNTER DIETRICH . . . 319 ;
    Description: DGG, DFG, SUB Göttingen
    Description: research
    Keywords: Geophysik ; Physische Geografie ; Atmosphäre ; Deformation ; Ethiopia ; Geoelectrics ; Geomagnetism ; Geomagnetismus ; Germany ; Gravitation ; Gravity ; Italy ; Laacher See ; Lithosphere ; Seismik ; Seismics ; Volcanism ; Vulkanismus ; FID-GEO-DE-7
    Language: German , English
    Type: anthology_digi
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  • 75
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    Physika-Verlag, Würzburg
    In:  Herausgeberexemplar (Archiv der DGG in Leipzig) | 8 Z NAT 2148
    Publication Date: 2019-01-26
    Description: Inhaltsverzeichnis : STUKENBRÖKER, B.: Ergebnisse von Erdgezeiten-Parallelregistrierungen mit drei ASKANIA-Gravimetern . . . 1 ; DRIMMEL, J., G. GANGL, R. GUTDEUTSCH, M. KOENIG und E. TRAPP: Modellseismische Experimente zur Interpretation makroseismischer Daten aus dem Bereich der Ostalpen . . . 21 ; BORM, G.: Solutions of Boundary Value Problems of Multilayer Analogs of Geoelectrics and Hydrology . . . 41 ; JACOBY, W. R.: Isostasie und Dichteverteilung in Kruste und oberem Mantel . . . . . . 79 ; BUNTEBARTH, G.: Modellberechnungen zur Temperatur-Tiefen-Verteilung im Bereich der Alpen und des Alpenvorlandes . . . 97 ; BUNTEBARTH, G.: Über die Größe der thermisch bedingten Bouguer-Anomalie in den Alpen . . . 109 ; EHRISMANN‚ W.‚ W. LEPPICH, O. LETTAU, O. ROSENBACH und P. STEINHAUSER: Gravimetrische Detail-Untersuchungen in den westlichen Hohen Tauern . . . 115 ; EHRISMANN, W.: Ein allgemeines Verfahren zur digitalen Berechnung der Schwerewirkung von Modellkörpern . . . 131 ; KAHLE, H.-G., and M. TALWANI: Gravimetric Indian Ocean Geoid . . . 167 ;
    Description: DGG, DFG, SUB Göttingen
    Description: research
    Keywords: Geophysik ; Physische Geografie ; Alpen ; Alpenvorland ; Erdmantel ; Geoelectrics ; Geoelektrik ; Gravimetrie ; Gravitation ; Hohen Tauern ; Hydrologie ; Hydrology ; Indian Ocean ; Seismik ; FID-GEO-DE-7
    Language: German , English
    Type: anthology_digi
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  • 76
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    Springer, Berlin
    In:  SUB Göttingen | 8 Z NAT 2148
    Publication Date: 2019-01-26
    Description: Inhaltsverzeichnis : Bonjer, K.-P., Gelbke, C., Gilg, B., Rouland, D., Mayer-Rosa, D., Massinon, B.: Seismicity and dynamics of the Upper Rhinegraben . . . 1 ; Zucca, J. J.: The crustal structure of the southern Rhinegraben from re-interpretation of seismic refraction data . . .13 ; Cavaliere, T., Jones, A. G.: On the identification of a transition zone in electrical conductivity between the lithosphere and asthenosphere: a plea for more precise phase data . . . 23 ; Brasse, H., Junge, A.: The influence of geomagnetic variations on pipelines and an application for largescale magnetotelluric depth sounding . . . 31 ; Nevanlinna, H.: Some Characteristics of the horizontal field variations around the geomagnetic jerk of 1970 . . . 37 ; Lühr, H., Klöcker, N., Thürey, S.: Ground-based observations of a very intense substorm-related pulsation event . . . 41 ; Dürschner, H.: Dreidimensionale Seismik in der Exploration auf Kohlenwasserstoff-Lagerstätten . . . 54 ; Varga, P.: Long-term variations recorded by extensometers . . . 68 ; Book reviews . . . 71 ; Preface . . . 75 ; Orr, D.: Magnetospheric hydromagnetic waves: their eigenperiods, amplitudes and phase variations; a tutorial introduction . . . 76 ; Ward, I.A.: ELF intensity levels at geostationary orbit and pulsating aurora . . . 85 ; Gough, H., Orr, D., Wedeken, U.: Ground observations of geomagnetic pulsations during a quiet magnetospheric interval correlated with satellite plasma measurements . . . 92 ; Gardner, M.: Period, phase and resonant structure of a pulsation event seen by the ISEE 1 and 2 spacecraft on 2-3 April 1978 . . . 102 ; Glaßmeier, K.H., Lester, M., Mier-Jedrzejowicz, W. A. C., Green, C. A., Rostoker, G., Orr, D., Wedeken, U., Junginger, H., Amata, E.: Pc5 pulsations and their possible source mechanisms: a case study . . . 108 ; Wedeken, U., Inhester, B., Korth‚ A., Glaßmeier, K.-H., Gendrin, R., Lanzerotti‚ L. J., Go