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  • 1
    Publikationsdatum: 2023-06-14
    Beschreibung: Lake Towuti is located on central Sulawesi/Indonesia, within the Indo Pacific Warm Pool, a globally important region for atmospheric heat and moisture budgets. In 2015 the Towuti Drilling Project recovered more than 1000 m of drill core from the lake, along with downhole geophysical logging data from two drilling sites. The cores constitute the longest continuous lacustrine sediment succession from the Indo Pacific Warm Pool. We combined lithological descriptions with borehole logging data and used multivariate statistics to better understand the cyclic sequence, paleoenvironments, and geochronology of these sediments. Accurate chronologies are crucial to analyze and interpret paleoclimate records. Astronomical tuning can help build age-depth models and fill gaps between age control points. Cyclostratigraphic investigations were conducted on a downhole magnetic susceptibility log from the lacustrine facies (10–98 m below lake floor) from a continuous record of sediments in Lake Towuti. This study provides insights into the sedimentary history of the basin between radiometric ages derived from dating a tephra layer (~ 797 ka) and C14-ages (~ 45 ka) in the cores. We derived an age model that spans from late marine isotope stage (MIS) 23 to late MIS 6 (903 ± 11 to 131 ± 67 ka). Although uncertainties caused by the relatively short record and the small differences in the physical properties of sediments limited the efficacy of our approach, we suggest that eccentricity cycles and/or global glacial-interglacial climate variability were the main drivers of local variations in hydroclimate in central Indonesia. We generated the first nearly complete age-depth model for the lacustrine facies of Lake Towuti and examined the potential of geophysical downhole logging for time estimation and lithological description. Future lake drilling projects will benefit from this approach, since logging data are available just after the drilling campaign, whereas core descriptions, though more resolved, only become available months to years later.
    Beschreibung: Deutsche Forschungsgemeinschaft (DE)
    Beschreibung: Projekt DEAL
    Schlagwort(e): ddc:551 ; Paleoclimate ; Geophysical downhole logging ; Cyclostratigraphy ; Lake Towuti ; Indo Pacific Warm Pool
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2023-09-12
    Beschreibung: Integrating palaeoclimatological proxies and historical records, which is necessary to achieve a more complete understanding of climate impacts on past societies, is a challenging task, often leading to unsatisfactory and even contradictory conclusions. This has until recently been the case for Italy, the heart of the Roman Empire, during the transition between Antiquity and the Middle Ages. In this paper, we present new high-resolution speleothem data from the Apuan Alps (Central Italy). The data document a period of very wet conditions in the sixth c. AD, probably related to synoptic atmospheric conditions similar to a negative phase of the North Atlantic Oscillation. For this century, there also exist a significant number of historical records of extreme hydroclimatic events, previously discarded as anecdotal. We show that this varied evidence reflects the increased frequency of floods and extreme rainfall events in Central and Northern Italy at the time. Moreover, we also show that these unusual hydroclimatic conditions overlapped with the increased presence of “water miracles” in Italian hagiographical accounts and social imagination. The miracles, performed by local Church leaders, strengthened the already growing authority of holy bishops and monks in Italian society during the crucial centuries that followed the “Fall of the Roman Empire”. Thus, the combination of natural and historical data allows us to show the degree to which the impact of climate variability on historical societies is determined not by the nature of the climatic phenomena per se, but by the culture and the structure of the society that experienced it.
    Beschreibung: Fondazione Cassa di Risparmio di Lucca
    Beschreibung: European Research Council http://dx.doi.org/10.13039/501100000781
    Schlagwort(e): ddc:551.6 ; Precipitation ; Roman Empire ; Miracles ; Social feedbacks ; Cultural change
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Publikationsdatum: 2024-03-22
    Beschreibung: Soil fauna drives crucial processes of energy and nutrient cycling in agricultural systems, and influences the quality of crops and pest incidence. Soil tillage is the most influential agricultural manipulation of soil structure, and has a profound influence on soil biology and its provision of ecosystem services. The objective of this study was to quantify through meta‐analyses the effects of reducing tillage intensity on density and diversity of soil micro‐ and mesofaunal communities, and how these effects vary among different pedoclimatic conditions and interact with concurrent management practices. We present the results of a global meta‐analysis of available literature data on the effects of different tillage intensities on taxonomic and functional groups of soil micro‐ and mesofauna. We collected paired observations (conventional vs. reduced forms of tillage/no‐tillage) from 133 studies across 33 countries. Our results show that reduced tillage intensity or no‐tillage increases the total density of springtails (+35%), mites (+23%), and enchytraeids (+37%) compared to more intense tillage methods. The meta‐analyses for different nematode feeding groups, life‐forms of springtails, and taxonomic mite groups showed higher densities under reduced forms of tillage compared to conventional tillage on omnivorous nematodes (+53%), epedaphic (+81%) and hemiedaphic (+84%) springtails, oribatid (+43%) and mesostigmatid (+57%) mites. Furthermore, the effects of reduced forms of tillage on soil micro‐ and mesofauna varied with depth, climate and soil texture, as well as with tillage method, tillage frequency, concurrent fertilisation, and herbicide application. Our findings suggest that reducing tillage intensity can have positive effects on the density of micro‐ and mesofaunal communities in areas subjected to long‐term intensive cultivation practices. Our results will be useful to support decision making on the management of soil faunal communities and will facilitate modelling efforts of soil biology in global agroecosystems. HIGHLIGHTS Global meta‐analysis to estimate the effect of reducing tillage intensity on micro‐ and mesofauna Reduced tillage or no‐tillage has positive effects on springtail, mite and enchytraeid density Effects vary among nematode feeding groups, springtail life forms and mite suborders Effects vary with texture, climate and depth and depend on the tillage method and frequency
    Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Beschreibung: https://doi.org/10.20387/bonares-eh0f-hj28
    Schlagwort(e): ddc:631.4 ; agricultural land use ; conservation agriculture ; conventional agriculture ; soil biodiversity ; soil cultivation
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 2024-04-25
    Beschreibung: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉There have been a number of theories proposed concerning the loss of relativistic electrons from the radiation belts. However, direct observations of loss were not possible on a number of previous missions due to the large field of view of the instruments and often high‐altitude orbits of satellites that did not allow researchers to isolate the precipitating electrons from the stably trapped. We use measurements from the ELFIN‐L suit of instruments flown on Lomonosov spacecraft at LEO orbit, which allows us to distinguish stably trapped from the drift loss cone electrons. The sun‐synchronous orbit of Lomonosov allows us to quantify scattering that occurred into the loss cone on the dawn‐side and the dusk‐side magnetosphere. The loss at MeV energies is observed predominantly on the dawn‐side, consistent with the loss induced by the chorus waves. The companion data publication provides processed measurements.〈/p〉
    Beschreibung: Plain Language Summary: There have been a number of models proposed concerning the loss of relativistic electrons from radiation belts. However, the direct observations of loss have been missing, as for most of the previous missions; the large aperture telescopes could not isolate the precipitating electrons from being stably trapped. In this study, we use measurements from ELFIN‐L on Lomonosov that allow for such separation and allow us to distinguish stably trapped from precipitating particles. We can also identify the particles that will be lost within one drift around the Earth, the so‐called drift loss cone. For understanding the loss processes and differentiating between them, it's crucially important to quantify where in local magnetic time these electrons will be scattered into the drift loss cone. Measurements from the ELFIN‐L instrument show that the loss at MeV energies is observed predominantly on the dawn side, consistent with the loss induced by the so‐called chorus plasma waves.〈/p〉
    Beschreibung: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉ELFIN‐L measurements allow comparing scattering into the loss cone on the dawn and dusk side〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Processed Level‐3 measurements are provided in the data publication〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Most of the relativistic electrons are scattered into the drift loss cone on the dawn side〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Beschreibung: National Science Foundation
    Beschreibung: Russian University Satellite Mission
    Beschreibung: Helmholtz Association
    Beschreibung: European Union's Horizon 2020 Research and Innovation Program
    Beschreibung: https://doi.org/10.5880/GFZ.2.7.2023.002
    Beschreibung: https://doi.org/10.5880/GFZ.2.7.2023.003
    Beschreibung: https://doi.org/10.5880/GFZ.2.7.2023.004
    Beschreibung: https://doi.org/10.5880/GFZ.2.7.2023.005
    Beschreibung: https://doi.org/10.5880/GFZ.2.7.2023.006
    Beschreibung: https://doi.org/10.5880/GFZ.2.7.2023.007
    Beschreibung: https://www.ncei.noaa.gov/data/poes-metop-space-environment-monitor/access/l1b/v01r00/
    Schlagwort(e): ddc:538.7 ; Electron Particle Detector ; ELFIN-L ; radiation belts ; electron loss ; drift loss cone
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Publikationsdatum: 2019-06-28
    Beschreibung: The Environment for Application Software Integration and Execution, EASIE, provides a methodology and a set of software utility programs to ease the task of coordinating engineering design and analysis codes. EASIE was designed to meet the needs of conceptual design engineers that face the task of integrating the results of many stand-alone engineering analysis programs. EASIE provides access to these programs via a quick, uniform, user-friendly interface. In addition, EASIE provides utilities which aid in the execution of the following tasks: selection of application programs, modification and review of program data, automatic definition and coordination of data files during program execution and a logging of steps executed throughout a design study. Volume 3, the Program Execution Guide, describes the executive capabilities provided by EASIE and defines the command language and menus available under Version 1.0. EASIE provides users with two basic modes of operation. One is the Application-Derived Executive (ADE) which provides users with sufficient guidance to quickly review data, select menu action items, and execute application programs. The second is the Complete Control Executive (CCE), which provides a full executive interface allowing users in-depth control of the design process.
    Schlagwort(e): COMPUTER PROGRAMMING AND SOFTWARE
    Materialart: NASA-TM-100575 , NAS 1.15:100575
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Publikationsdatum: 2019-07-19
    Beschreibung: The paper discusses development of various NDE techniques to detect cracks in A40 steel poppets used in a valve of the fuel system of the Space Shuttle Orbiter. The valve assembly experiences a severe high cycle fatigue environment during its operation. Cracks were discovered at the radius of the poppet flange. Experience shows that very small cracks or material anomalies do not cause failure in a single operation event. While the design is being modified to eliminate the issue, NDE has been used to screen the poppets for cracks before every use. Several surface flaw detection techniques were considered and a few NDE techniques were developed to provide NDE screening for the flaw detection. The primary method used was the eddy current testing. In the eddy current technique, the X-Y channel test data from the eddy current instrument was recorded as computer files. A Matlab data review and plotting application was developed to analyze the data files. The Matlab application provides much higher resolution than the eddy current instrument that was used to acquire the data. Other techniques that were used included ultrasonic surface wave and magnetic particle testing. A probability of detection (POD) study was undertaken to determine the 90/95 size for the eddy current technique. This study used specimens with same geometry and material as the poppet. Fatigue cracks were grown in these specimens. Information on results of the NDE techniques and results of the POD study are provided.
    Schlagwort(e): Propellants and Fuels
    Materialart: JSC-CN-19224 , JSC-CN-19296 , Aircraft Airworthiness and Sustainment Conference; May 10, 2010 - May 13, 2010; Austin, Texas; United States|ASNT Research Symposium and Spring Conference; Mar 22, 2010 - Mar 26, 2010; Williamsburg, VA; United States
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Publikationsdatum: 2019-07-13
    Beschreibung: We report striking changes in the broadband spectrum of the compact jet of the black hole transient MAXI J1836194 over state transitions during its discovery outburst in 2011. A fading of the optical-infrared (IR) flux occurred as the source entered the hard-intermediate state, followed by a brightening as it returned to the hard state. The optical-IR spectrum was consistent with a power law from optically thin synchrotron emission, except when the X-ray spectrum was softest. By fitting the radio to optical spectra with a broken power law, we constrain the frequency and flux of the optically thick/thin break in the jet synchrotron spectrum. The break gradually shifted to higher frequencies as the source hardened at X-ray energies, from approx 10(exp 11) to approx 4 10(exp 13) Hz. The radiative jet luminosity integrated over the spectrum appeared to be greatest when the source entered the hard state during the outburst decay (although this is dependent on the high-energy cooling break, which is not seen directly), even though the radio flux was fading at the time. The physical process responsible for suppressing and reactivating the jet (neither of which are instantaneous but occur on timescales of weeks) is uncertain, but could arise from the varying inner accretion disk radius regulating the fraction of accreting matter that is channeled into the jet. This provides an unprecedented insight into the connection between inflow and outflow, and has implications for the conditions required for jets to be produced, and hence their launching process.
    Schlagwort(e): Astrophysics
    Materialart: GSFC-E-DAA-TN10528 , The Astrophysical Journal; 768; 2; L35
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Publikationsdatum: 2019-07-13
    Beschreibung: No abstract available
    Schlagwort(e): Composite Materials
    Materialart: KSC-2013-057 , ASM AeroMat 2013 Conference; Apr 02, 2013 - Apr 05, 2013; Bellevue, WA; United States
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Publikationsdatum: 2019-07-19
    Beschreibung: Composite Overwrapped Pressure Vessels (COPVs) are used in essentially all NASA spacecraft, launch. vehicles and payloads to contain high-pressure fluids for propulsion, life support systems and science experiments. Failure of any COPV either in flight or during ground processing would result in catastrophic damage to the spacecraft or payload, and could lead to loss of life. Therefore, NASA continues to investigate new methods to non-destructively inspect (NDE) COPVs for structural anomalies and to provide a means for in-situ structural health monitoring (SHM) during operational service. Partnering with JENTEK Sensors, engineers at NASA, Kennedy Space Center have successfully conducted a proof-of-concept study to develop Meandering Winding Magnetometer (MWM) eddy current sensors designed to make direct measurements of the stresses of the internal layers of a carbon fiber composite wrapped COPV. During this study three different MWM sensors were tested at three orientations to demonstrate the ability of the technology to measure stresses at various fiber orientations and depths. These results showed good correlation with actual surface strain gage measurements. MWM-Array technology for scanning COPVs can reliably be used to image and detect mechanical damage. To validate this conclusion, several COPVs were scanned to obtain a baseline, and then each COPV was impacted at varying energy levels and then rescanned. The baseline subtracted images were used to demonstrate damage detection. These scans were performed with two different MWM-Arrays. with different geometries for near-surface and deeper penetration imaging at multiple frequencies and in multiple orientations of the linear MWM drive. This presentation will include a review of micromechanical models that relate measured sensor responses to composite material constituent properties, validated by the proof of concept study, as the basis for SHM and NDE data analysis as well as potential improvements including design changes to miniaturize and make the sensors durable in the vacuum of space
    Schlagwort(e): Quality Assurance and Reliability
    Materialart: KSC-2011-289 , 2012 Aircraft Airworthiness and Sustainment Conference; Apr 02, 2012 - Apr 05, 2012; Baltimore, MD; United States
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 2019-07-17
    Beschreibung: As part of the second Aerosol Characterization Experiment (ACE-2) during June and July of 1997, aerosol size distributions were measured on board the CIRPAS Pelican aircraft through the use of a DMA and two OPCS. During the campaign, the boundary layer aerosol typically possessed characteristics representative of a background marine aerosol or a continentally influenced aerosol, while the free tropospheric aerosol was characterized by the presence or absence of a Saharan dust layer. A range of radiative closure comparisons were made using the data obtained during vertical profiles flown on four missions. Of particular interest here are the comparisons made between the optical properties as determined through the use of measured aerosol size distributions and those measured directly by an airborne 14-wavelength sunphotometer and three nephelometers. Variations in the relative humidity associated with each of the direct measurements required consideration of the hygroscopic properties of the aerosol for size distribution based calculations. Simultaneous comparison with such a wide range of directly measured optical parameters not only offers evidence of the validity of the physicochemical description of the aerosol when closure is achieved, but also provides insight into potential sources of error when some or all of the comparisons result in disagreement. Agreement between the derived and directly measured optical properties varied for different measurements and for different cases. Averaged over the four case studies, the derived extinction coefficient at 525 nm exceeded that measured by the sunphotomoter by 2.5% in the clean boundary later, but underestimated measurements by 13% during pollution events. For measurements within the free troposphere, the mean derived extinction coefficient was 3.3% and 17% less than that measured by the sunphotometer during dusty and nondusty conditions, respectively. Likewise, averaged discrepancies between the derived and measured scattering coefficient were -9.6%, +4.7%, +17%, and -41% for measurements within the clean boundary layer, polluted boundary layer, free troposphere with a dust layer, and free troposphere without a dust layer, respectively. Each of these quantities, as well as the majority of the 〉 100 individual comparisons from which they were averaged, were within estimated uncertainties.
    Schlagwort(e): Environment Pollution
    Materialart: Analysis of Atmospheric Aerosol Data Sets and Application of Radiative Transfer Models to Compute Aerosol Effects
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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