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  • 1
    Publikationsdatum: 2024-03-06
    Beschreibung: Numerical prediction of landslide runout and deposition is important for estimating landslide risk and developing mitigation plans. The choice of a suitable model and its parameters and a confident calibration strategy are crucial for numerical simulations. Here, we evaluated two constitutive models with a three‐dimensional smoothed particle hydrodynamics (SPH) method by simulating the catastrophic 11 October 2018 Baige landslide. The results indicate that both the soil mechanic and fluid models can capture the dynamic runout and deposition morphology while using different values of input parameters. A point‐wise comparison of deposit elevation can minimize the calibration error. Numerical models were constrained accurately by utilizing both the static observation data and dynamic seismic signals. The effects of friction on deep‐seated landslides motion and deposition are more significant than cohesion. The 3D model includes the effects of shear stresses and velocities inside the material body, resulting in a reduced friction coefficient compared to the 2D model (e.g., depth‐averaged model). Our study highlights the potential of the 3D SPH method for modeling large‐scale complex landslides.
    Beschreibung: Plain Language Summary: Landslides belong to a type of earth surface process recognized by their high damage potential. Computer models can simulate the landslides' movement to predict speed, forces, and deposition, which can help to delineate areas at risk and to design mitigation measures. We simulated the 2018 Baige landslide in China with a method known as smoothed particle hydrodynamics (SPH), to test whether it is suitable for landslide simulation and to investigate protocols for model calibration when including seismic data in addition to information on the landslide's deposit. In this method, the landslide body is represented by millions of small, moving, interacting particles, which offers advantages over established models in terms of computation time and details in the simulation. We find that SPH is suitable for modeling large‐scale natural landslides. The seismic data are more valuable in the model calibration than landslide deposit observations. The new approach yields landslide simulations that deliver more details on particle velocities within the landslide body, and their spatial and temporal distribution. These details can be used to infer the properties of landslides during the sliding process, which helps to better understand landslides in general and to set up models for events where little data are available.
    Beschreibung: Key Points: A three‐dimensional mesh‐less graphics processing unit‐accelerated smoothed particle hydrodynamics formulation is suitable for modeling large‐scale natural landslides. The selection of an appropriate constitutive model depends on the landslide features and materials. Including dynamic seismic signals into numerical model calibration routines in addition to topographic changes improves calibration.
    Beschreibung: National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809
    Beschreibung: Sichuan Science and Technology Program
    Beschreibung: Helmholtz‐ocpc Postdoc Program fellowship
    Beschreibung: Sino‐German Mobility programme
    Beschreibung: Youth Innovation Promotion Association of the Chinese Academy of Sciences http://dx.doi.org/10.13039/501100004739
    Beschreibung: https://figshare.com/articles/software/LOQUAT-master_zip/20486088
    Beschreibung: https://10.0.20.161/zenodo.7408675
    Schlagwort(e): ddc:551.3 ; landslides ; numerical modeling ; constitutive model ; model calibration routines ; friction ; cohesion
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: β-Arrestins are key negative regulators and scaffolds of G protein-coupled receptor (GPCR) signalling. β-Arrestin1 and β-arrestin2 preferentially bind to the phosphorylated GPCRs in response to agonist stimulation, resulting in receptor internalization and desensitization. The critical roles of GPCR kinases (GRKs)-catalyzed receptor phosphorylation and interaction of β-arrestins with the phosphorylated receptor in receptor internalization are well established. However, emerging evidence suggests that an agonist-stimulated internalization mechanism that is independent of receptor phosphorylation may also be employed in some cases, although the molecular mechanism for the phosphorylation-independent GPCR internalization is not clear. The current study investigated the role of receptor phosphorylation and the involvement of different β-arrestin subtypes in agonist-induced δ-opioid receptor (DOR) internalization in HEK293 cells. Results from flow cytometry, fluorescence microscopy, and surface biotin labelling experiments showed that elimination of agonist-induced DOR phosphorylation by mutation GRK binding or phosphorylation sites only partially blocked agonist-induced receptor internalization, indicating the presence of an agonist-induced, GRK-independent mechanism for DOR internalization. Fluorescence and co-immunoprecipitation studies indicated that both the wild-type DOR and the phosphorylation-deficient mutant receptor could bind and recruit β-arrestin1 and β-arrestin2 to the plasma membrane in an agonist-stimulated manner. Furthermore, internalization of both the wild-type and phosphorylation-deficient receptors was increased by overexpression of either type of β-arrestins and blocked by dominant-negative mutants of β-arrestin-mediated internalization, demonstrating that both phosphorylation-dependent and -independent internalization require β-arrestin. Moreover, double-stranded RNA-mediated interference experiments showed that either β-arrestin1 or β-arrestin2 subtype-specific RNAi only partially inhibited agonist-induced internalization of the wild-type DOR. However, agonist-induced internalization of the phosphorylation-deficient DOR was not affected by β-arrestin1-specific RNAi but was blocked by RNAi against β-arrestin2 subtype. These data indicate that endogenous β-arrestin1 functions exclusively in the phosphorylation-dependent receptor internalization, whereas endogenous β-arrestin2, but not β-arrestin1, is required for the phosphorylation-independent receptor internalization. These results thus provide the first evidence of different requirement for β-arrestin isoforms in the agonist induced phosphorylation-dependent and -independent GPCR internalization.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Publikationsdatum: 2013-06-29
    Beschreibung: Article The growth of high-quality graphene over large areas is essential for the realization of graphene-based electronic devices. Zhou et al. report a new pathway to grow single crystalline graphene of up to 5 mm in size, with very good electronic performance and high uniformity. Nature Communications doi: 10.1038/ncomms3096 Authors: Hailong Zhou, Woo Jong Yu, Lixin Liu, Rui Cheng, Yu Chen, Xiaoqing Huang, Yuan Liu, Yang Wang, Yu Huang, Xiangfeng Duan
    Digitale ISSN: 2041-1723
    Thema: Biologie , Chemie und Pharmazie , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Publikationsdatum: 2013-07-05
    Beschreibung: ABSTRACT On the basis of meteorological station records during 1961–2010, we investigate the variations of temperature and precipitation in the Qaidam Basin. Results show that climate warming is significant in the region of Qaidam Basin over the past 50 years, with an average warming rate of 0.53 °C 10a −1 . The largest and smallest warming rate happened at Mangya station (0.89 °C 10a −1 ) and Lenghu station (0.24 °C 10a −1 ), respectively. Seasonal warming was greatest in winter at eight meteorological stations, ranging from 0.43 °C 10a −1 (Lenghu station) to 1.01 °C 10a −1 (Delingha station). Since 1961, the annual precipitation has increased with a rate of 7.38 mm 10a −1 . Seasonal precipitation mainly increased in summer (4.02 mm 10a −1 ). The maximum precipitation increase occurred at Delingha station (25.09 mm 10a −1 ) and the minimum at Lenghu station (0.10 mm 10a −1 ). The elevation dependency of warming trends is unremarkable because most of the stations are located at lower altitudes. It is suggested that sunshine duration is related to the tendencies of temperature increase at different stations. Pollution emissions from industrial processes (i.e. brown clouds) and urbanization are the main factors contributing to the warming climate. Furthermore, the predominant weakening of zonal wind speed over the Tibetan Plateau resulted from the global warming also contributes to the climate warming in the Qaidam Basin. Consequently, the warming rate in the Qaidam Basin is much higher than in other regions over the Tibetan Plateau. The Qaidam Basin is thus considered to be the most susceptible region with the most significant warming in the Tibetan Plateau.
    Print ISSN: 0899-8418
    Digitale ISSN: 1097-0088
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley-Blackwell
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    Publikationsdatum: 2013-11-23
    Beschreibung: Article In ferroelectric thin films, ferroelastic domains affect the features of polarization switching. Gao et al. perform real-time transmission electron microscopy measurements and show that ferroelastic domains can hinder the switching via formation of a transient interface layer with a dipole glass structure. Nature Communications doi: 10.1038/ncomms3791 Authors: Peng Gao, Jason Britson, Jacob R. Jokisaari, Christopher T. Nelson, Seung-Hyub Baek, Yiran Wang, Chang-Beom Eom, Long-Qing Chen, Xiaoqing Pan
    Digitale ISSN: 2041-1723
    Thema: Biologie , Chemie und Pharmazie , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Publikationsdatum: 2016-05-20
    Beschreibung: According to Bragg theory, capillary waves are the predominant scatterers of high-frequency band (such as Ka-band) microwave radiation from the surface of the ocean. Therefore, understanding the modulation mechanism of capillary waves is an important foundation for interpreting high-frequency microwave remote sensing images of the surface of the sea. In our experiments, we discovered that modulations of capillary waves are significantly larger than the values predicted by the classical theory. Further, analysis shows that the difference in restoring force results in an inflection point while the phase velocity changes from gravity waves region to capillary waves region, and this results in the capillary waves being able to resonate with gravity waves when the phase velocity of the gravity waves is equal to the group velocity of the capillary waves. Consequently, we propose a coupling modulation model in which the current modulates the capillary wave indirectly by modulating the resonant gravity waves, and the modulation of the former is approximated by that of the latter. This model very effectively explains the results discovered in our experiments. Further, based on Bragg scattering theory and this coupling modulation model, we simulate the modulation of normalized radar cross-section (NRCS) of typical internal waves and show that the high-frequency bands are superior to the low-frequency bands because of their greater modulation of and better radiometric resolution. This result provides new support for choice of radar band for observation of wave-current modulation oceanic phenomena such as internal waves, fronts, and shears. This article is protected by copyright. All rights reserved.
    Print ISSN: 0148-0227
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley-Blackwell im Namen von American Geophysical Union (AGU).
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  • 7
    Publikationsdatum: 2018-04-21
    Beschreibung: Water, Vol. 10, Pages 510: Surface Water Quality Evaluation Based on a Game Theory-Based Cloud Model Water doi: 10.3390/w10040510 Authors: Bing Yang Chengguang Lai Xiaohong Chen Xiaoqing Wu Yanhu He Water quality evaluation is an essential measure to analyze water quality. However, excessive randomness and fuzziness affect the process of evaluation, thus reducing the accuracy of evaluation. Therefore, this study proposed a cloud model for evaluating the water quality to alleviate this problem. Analytic hierarchy process and entropy theory were used to calculate the subjective weight and objective weight, respectively, and then they were coupled as a combination weight (CW) via game theory. The proposed game theory-based cloud model (GCM) was then applied to the Qixinggang section of the Beijiang River. The results show that the CW ranks fecal coliform as the most important factor, followed by total nitrogen and total phosphorus, while biochemical oxygen demand and fluoride were considered least important. There were 19 months (31.67%) at grade I, 39 months (65.00%) at grade II, and one month at grade IV and grade V during 2010–2014. A total of 52 months (86.6%) of GCM were identical to the comprehensive evaluation result (CER). The obtained water quality grades of GCM are close to the grades of the analytic hierarchy process weight (AHPW) due to the weight coefficient of AHPW set to 0.7487. Generally, one or two grade gaps exist among the results of the three groups of weights, suggesting that the index weight is not particularly sensitive to the cloud model. The evaluated accuracy of water quality can be improved by modifying the quantitative boundaries. This study could provide a reference for water quality evaluation, prevention, and improvement of water quality assessment and other applications.
    Digitale ISSN: 2073-4441
    Thema: Energietechnik
    Publiziert von MDPI Publishing
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    Publikationsdatum: 2014-01-22
    Beschreibung: Wind-blown dust derived from the arid and semi-arid regions is an important atmospheric component affecting the Earth’s radiation budget. Dust storms are prevailing in central Asia. Deposition of atmospheric dust in snow was measured on Glacier No.12 (5040 ;m a.s.l.) in the Laohugou Basin and Shiyi Glacier (4510 ;m a.s.l.) in the Yeniugou Basin, of western Qilian Mountains, China, mainly focusing on dust concentration and size distribution, chemistry, SEM–EDX analysis and Nd–Sr isotopic composition. An analysis of spatial distribution of dust concentration and size distribution in the snow cover at two sites suggests that deposition of dust in western Qilian Mountains is different between sites as the environment changes from west to east. Mean mass concentration of dust with 0.57 〈 d 〈40 ;μm in the snow is 3461 ;μg kg −1 on Glacier No.12 and 2876 μg kg −1 on Shiyi Glacier, respectively. Annual flux of dust deposition to western Qilian Mountains has a range of 143.8–207.6 ;μg cm −2 yr −1 for particles with 0.57 〈 d 〈40 ;μm. Dust layers in the snowpit contain Ca- and Na-rich materials typically found in Asian dust particles. Number–size distribution indicated that most of the dust diameter is 〈2.0 ;μm, implying the significant influences of finer particles to alpine glacier regions of central Asia. Volume size distributions of dust particles showed single-modal structures having volume median diameters from 3 to 22 ;μm, which is comparable to the results of dust deposition on glaciers of the adjacent Tianshan Mountains in western China. SEM–EDX analysis suggested that dust particles were mainly composed of mineral particles, besides some fly ash particles and soot. EDX shows that mineral particles contain Si-, Al-, Ca-, K-, and Fe-rich materials, such as quartz, albite, aluminate, etc. The Nd–Sr isotopic composition of insoluble particles in two glaciers showed that Badain Jaran Desert and Qaidam Basin were the most possible source regions of dust in the western Qilian Mountains. Physicochemical constituents of dust indicated that the snowpack was influenced by both local atmospheric environment, e.g. local dust, and anthropogenic activities in central Asia. Keywords: atmospheric dust, physicochemical characteristics, SEM–EDX, dust source, glacier melting, western Qilian Mountains (Published: 21 January 2013) Citation: Tellus B 2014, 66 , 20956, http://dx.doi.org/10.3402/tellusb.v66.20956
    Print ISSN: 0280-6509
    Digitale ISSN: 1600-0889
    Thema: Geographie , Physik
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    Publikationsdatum: 2014-05-04
    Beschreibung: Article The electromechanical response of thin film ferroelectric devices is considerably influenced by ferroelastic domains. Here, the authors observe that these ferroeleastic domains can be stabilized by dislocations, providing feedback for a better control over the properties of these devices. Nature Communications doi: 10.1038/ncomms4801 Authors: Peng Gao, Jason Britson, Christopher T. Nelson, Jacob R. Jokisaari, Chen Duan, Morgan Trassin, Seung-Hyub Baek, Hua Guo, Linze Li, Yiran Wang, Ying-Hao Chu, Andrew M. Minor, Chang-Beom Eom, Ramamoorthy Ramesh, Long-Qing Chen, Xiaoqing Pan
    Digitale ISSN: 2041-1723
    Thema: Biologie , Chemie und Pharmazie , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    Publikationsdatum: 2018-07-16
    Beschreibung: Sensors, Vol. 18, Pages 2292: A Novel Method for Estimating Free Space 3D Point-of-Regard Using Pupillary Reflex and Line-of-Sight Convergence Points Sensors doi: 10.3390/s18072292 Authors: Zijing Wan Xiangjun Wang Kai Zhou Xiaoyun Chen Xiaoqing Wang In this paper, a novel 3D gaze estimation method for a wearable gaze tracking device is proposed. This method is based on the pupillary accommodation reflex of human vision. Firstly, a 3D gaze measurement model is built. By uniting the line-of-sight convergence point and the size of the pupil, this model can be used to measure the 3D Point-of-Regard in free space. Secondly, a gaze tracking device is described. By using four cameras and semi-transparent mirrors, the gaze tracking device can accurately extract the spatial coordinates of the pupil and eye corner of the human eye from images. Thirdly, a simple calibration process of the measuring system is proposed. This method can be sketched as follows: (1) each eye is imaged by a pair of binocular stereo cameras, and the setting of semi-transparent mirrors can support a better field of view; (2) the spatial coordinates of the pupil center and the inner corner of the eye in the images of the stereo cameras are extracted, and the pupil size is calculated with the features of the gaze estimation method; (3) the pupil size and the line-of-sight convergence point when watching the calibration target at different distances are computed, and the parameters of the gaze estimation model are determined. Fourthly, an algorithm for searching the line-of-sight convergence point is proposed, and the 3D Point-of-Regard is estimated by using the obtained line-of-sight measurement model. Three groups of experiments were conducted to prove the effectiveness of the proposed method. This approach enables people to obtain the spatial coordinates of the Point-of-Regard in free space, which has great potential in the application of wearable devices.
    Digitale ISSN: 1424-8220
    Thema: Chemie und Pharmazie , Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von MDPI Publishing
    Standort Signatur Einschränkungen Verfügbarkeit
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