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  • 1
    Online Resource
    Online Resource
    Dordrecht :Springer Netherlands,
    Keywords: Microbial proteins. ; Electronic books.
    Type of Medium: Online Resource
    Pages: 1 online resource (219 pages)
    Edition: 1st ed.
    ISBN: 9781402028441
    DDC: 636.208522
    Language: English
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  • 2
    Publication Date: 2020-02-12
    Description: The multi-constellation Global Navigation Satellite Systems (GNSS) offers promising potential for the retrieval of real-time (RT) atmospheric parameters to support time-critical meteorological applications, such as nowcasting or regional short-term forecasts. In this study, we processed GNSS data from the globally distributed Multi-GNSS Experiment (MGEX) network of about 30 ground stations by using the precise point positioning (PPP) technique for retrieving RT multi-GNSS tropospheric delays. RT satellite orbit and clock product streams from the International GNSS Service (IGS) were used. Meanwhile, we assessed the quality of clock and orbit products provided by different IGS RT services, called CLK01, CLK81, CLK92, GFZC2, and GFZD2, respectively. Using the RT orbit and clock products, the performances of the RT zenith total delays (ZTD) retrieved from single-system as well as from multi-GNSS combined observations were evaluated by comparing with the U.S. Naval Observatory (USNO) final troposphere products. With the addition of multi-GNSS observations, RT ZTD estimates with higher accuracy and enhanced reliability compared to the single-system solution can be obtained. Compared with the Global Positioning System (GPS)-only solution, the improvements in the initialization time of ZTD estimates are about 5.8% and 8.1% with the dual-system and the four-system combinations, respectively. The RT ZTD estimates retrieved with the GFZC2 products outperform those derived from the other IGS-RT products. In the GFZC2 solution, the accuracy of about 5.05 mm for the RT estimated ZTD can be achieved with fixing station coordinates. The results also confirm that the accuracy improvement (about 22.2%) can be achieved for the real-time estimated ZTDs by using multi-GNSS observables, compared to the GPS-only solution. In the multi-GNSS solution, the accuracy of real-time retrieved ZTDs can be improved by a factor of up to 2.7 in the fixing coordinate mode, compared with that in the kinematic mode.
    Language: English
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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  • 3
    Publication Date: 2021-10-22
    Description: Geobiology explores how Earth's system has changed over the course of geologic history and how living organisms on this planet are impacted by or are indeed causing these changes. For decades, geologists, paleontologists, and geochemists have generated data to investigate these topics. Foundational efforts in sedimentary geochemistry utilized spreadsheets for data storage and analysis, suitable for several thousand samples, but not practical or scalable for larger, more complex datasets. As results have accumulated, researchers have increasingly gravitated toward larger compilations and statistical tools. New data frameworks have become necessary to handle larger sample sets and encourage more sophisticated or even standardized statistical analyses. In this paper, we describe the Sedimentary Geochemistry and Paleoenvironments Project (SGP; Figure 1), which is an open, community-oriented, database-driven research consortium. The goals of SGP are to (1) create a relational database tailored to the needs of the deep-time (millions to billions of years) sedimentary geochemical research community, including assembling and curating published and associated unpublished data; (2) create a website where data can be retrieved in a flexible way; and (3) build a collaborative consortium where researchers are incentivized to contribute data by giving them priority access and the opportunity to work on exciting questions in group papers. Finally, and more idealistically, the goal was to establish a culture of modern data management and data analysis in sedimentary geochemistry. Relative to many other fields, the main emphasis in our field has been on instrument measurement of sedimentary geochemical data rather than data analysis (compared with fields like ecology, for instance, where the post-experiment ANOVA (analysis of variance) is customary). Thus, the longer-term goal was to build a collaborative environment where geobiologists and geologists can work and learn together to assess changes in geochemical signatures through Earth history. With respect to the data product, SGP is focused on assembling a well-vetted and comprehensive dataset that is tractable to multivariate statistical analyses accounting for multiple geological and methodological biases. Phase 1 of the project, which focused on the Neoproterozoic and Paleozoic, has been completed. Future phases will capture a broader range of geologic time, data types, and geography. The database contains tens of thousands of unpublished data points provided by consortium members, as well as detailed metadata that go beyond what is contained in papers. In many cases, these represent measurements that are tangential to a given published study but still of high utility to database studies; these allow the community to address questions that would be impossible to answer solely with the published data. For instance, in order to use a proxy such as Mo/TOC (total organic carbon) ratios in mudrocks deposited under a euxinic water column, the full suite of trace metal, iron speciation, and total organic carbon data is needed. Likewise, geospatial information is required to account for sampling biases, and many statistical learning approaches cannot accept, or have difficulty with, incomplete geological predictor variables. Ultimately, it is this complete data matrix that will allow for SGP’s most insightful analyses.
    Language: English
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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  • 4
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    In:  Protokoll zum 23. Schmucker-Weidelt-Kolloquium für Elektromagnetische Tiefenforschung
    Publication Date: 2020-02-12
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
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  • 5
    Publication Date: 2020-02-14
    Description: The correction of higher-order ionospheric (HOI) delays remaining in the dual-frequency ionosphere-free combined observations is suggested after the confirmation of its impact on precise Global Navigation Satellite System (GNSS) data processing. However, in the precise orbit determination (POD) for generating ultra-rapid orbits, the higher-order corrections are not always considered most likely because a RT ionospheric model needed for calculating the higher-order corrections is hardly available or the HOI impact is believed rather small compared to the accuracy of the predicted orbit. With the increasing requirement on the positioning performances from various applications, providing more accurate and reliable ultra-rapid orbits becomes an essential task of the real-time GNSS precise positioning services. In this contribution, the temporal–spatial characteristics of HOI effects on GNSS observables are investigated thoroughly using data collected from International GNSS Service (IGS) global ground stations and fluctuations of the higher-order delays up to several centimeters are detected during periods of high ionospheric activity. Hereafter, we evaluate the HOI effects on the multi-GNSS POD based on a network with globally distributed IGS stations. Results show that owing to the applied HOI corrections, the agreement of overlapping orbits can be improved significantly for all satellites and especially in radial direction. The three-dimensional RMS values of the overlapping differences are reduced from 1.6, 2.0, 4.6 and 1.7 to 1.0, 1.1, 3.4, and 1.5 cm for GPS, GALILEO, BDS, and GLONASS, respectively. Furthermore, the orbit improvement is also confirmed by the satellite laser ranging (SLR) observations over a 2-month time period where the STD of SLR residuals is reduced by HOI corrections from 6.4 to 5.3 cm for the BDS-IGSO satellites.
    Language: English
    Type: info:eu-repo/semantics/article
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  • 6
    Publication Date: 2022-01-28
    Description: Lagrangian particle-based smoothed particle hydrodynamics (SPH) is increasingly widely used in landslide modelling. This paper investigates four important issues not addressed by previous studies on SPH modelling of large-scale landslides, i.e., convergence property, influence of constitutive parameters, scale effect and friction reduction, and influence of different treatments of the viscous effect. The GPU-acceleration technique is employed to achieve high-resolution three-dimensional (3D) modelling. The Baige landslide is investigated by comparing numerical results with field data, and detailed analyses on the four issues are provided. Suggestions on particle resolution, constitutive parameter, and formulations of viscous discretization are also presented for future SPH modelling of large-scale landslides.
    Language: English
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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  • 7
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    In:  XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
    Publication Date: 2023-05-03
    Description: The popular probability integral transform (PIT) uniform plot presents informative empirical illustrations of five types of ensemble forecasts, i.e., reliable, under-confident, over-confident, negatively biased and positively biased. This paper has built a novel two-stage framework upon the PIT uniform plot to quantitatively examine the forecast attributes of bias and reliability. The first stage utilizes the test statistic on bias to examine whether the mean of PIT values is equal to the theoretical mean of standard uniform distribution. Then, the second stage uses the test statistic on reliability to examine whether the mean squared deviation from the theoretical mean is equal to the theoretical variance of standard uniform distribution. Therefore, by using the two-tailed bootstrap hypothesis testing, the first stage identifies unbiased ensemble forecasts, negatively biased forecasts and positively biased forecasts; the second stage focuses on unbiased ensemble forecasts to furthermore identify reliable forecasts, under-confident forecasts and over-confident forecasts. Numerical experiments are devised for the National Centers for Environmental Prediction (NCEP)’s Climate Forecast System version 2 (CFSv2) ensemble forecasts of global precipitation. The results highlight the existence of various shapes of the PIT uniform plots. Due to extreme values of observed precipitation, the PIT uniform plots in some cases can substantially deviate from the 1:1 line even though the mean and variance of ensemble forecasts are respectively in accordance with the mean and variance of observations. Nevertheless, the two-stage framework along with the two test statistics serves as a robust tool for the verification of ensemble hydroclimatic forecasts.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
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  • 8
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    In:  XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
    Publication Date: 2023-05-15
    Description: The normal modes (i.e. Earth's free oscillations) are long-period low-frequency seismic signals, which are excited by a variety of factors, such as earthquakes, volcanic eruption, landslide, avalanche and so on, are an essential vehicle for global seismic tomography to elucidate large-scale heterogeneities within the deep Earth. Accurate extraction of signals on normal mode spectrum is a prerequisite for the imaging inversion, providing the differences between the observed and synthetic normal mode spectrum. However, the normal mode spectrum has great complexity due to many structural factors within the Earth, so unacceptable false and dismissed selections of the signals always occur, which hinder the development of exploration of the deep Earth’s deep interior based on normal mode data. To address these problems, we build a deep-learning based neural network, named ModeNet, which is capable of precisely and efficient selecting the frequency windows to cover the target normal modal signals on a noisy spectrum, which could outperform the conventional spectrum-FLEXWIN method without relying on comparisons with synthetics. We also define our own method to evaluate the performance of ModeNet on the testing set and obtain a precision as high as ~0.98. Moreover, ModeNet achieves good generalization in processing seismograms of different events with different noise levels, components, and time window data, as well as superconductivity-gravimeter observations. Therefore, ModeNet could be implemented as a valuable tool for the future deep Earth inversion.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
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  • 9
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    In:  XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
    Publication Date: 2023-05-15
    Description: The 15 January 2022 eruption of the Hunga-Tonga volcano generated huge explosions in the atmosphere, which excited various kinds of atmospheric disturbances detected globally by ground-based or spaceborne instruments. Here we show our simulations of these atmospheric waves along with a summary of observation findings. The modelling is achieved by a complete synthetic seismogram calculator (QSSP) considering a hybrid approach of the normal mode theory and matrix method in a layered spherical Earth model including the atmosphere. The synthetic waveform profile, the spectra for nearby stations, as well as the dispersion curves extracted in an array all show good agreement with the observations. Based on these results, especially the dispersion curves for phase speed, we propose a new interpretation for the horizontally propagating Lamb wave. In this model, the Lamb wave can be regarded as the fundamental gravity modes in low frequency band and the fundamental acoustic modes in high frequency band, respectively. The findings may provide new perspectives on the analysis of general atmospheric waves and show the potential of seismic techniques on atmospheric problems.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
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  • 10
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    In:  XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)
    Publication Date: 2023-05-15
    Description: Intensified climate change is already affecting water quality around the world. The fundamental goal of water quality engineering is to ensure water safety to human and the environment. Traditional water quality engineering includes monitoring, evaluation, and control of key water quality parameters, most of which however do not consider potential health impact of mixture pollutants - a reality faced by terminal water users. To focus on one of the original goals of water quality engineering—human health and environmental protection—here we advocate toxicity-oriented water quality monitoring and control. This presentation showcases some of our efforts to achieve this goal. Specifically, as a complement to traditional water quality parameters, we assessed water toxicity using high-sensitivity toxicological endpoints, and subsequently investigated the performance of some water quality intervention strategies in modulating water toxicity. Furthermore, we applied the toxicity concept to existing water treatment design theories to facilitate toxicity-oriented water quality control designs. Suggestions for the next steps are also discussed. We hope that our work will stimulate the interest of water quality scientists and engineers in improving and adopting the toxicity-oriented approach to water quality monitoring and control.
    Language: English
    Type: info:eu-repo/semantics/conferenceObject
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