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  • MDPI AG  (14)
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Verlag/Herausgeber
  • MDPI AG  (14)
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Erscheinungszeitraum
  • 1
    In: Applied Sciences, MDPI AG, Vol. 10, No. 4 ( 2020-02-21), p. 1461-
    Kurzfassung: Low-temperature discharged water from thermally-stratified reservoirs in spring and summer will have a negative environmental impact on fish breeding and agricultural irrigation downstream. The temperature-control curtain (TCC) is a selective withdrawal structure that can effectively change the discharged water temperature. Compared with a traditional selective withdrawal project, a TCC project has the advantages of low cost and simple construction and can even be added to operating reservoirs without impacting power generation. Analysis of the load characteristics is the key to the application of TCC engineering. This paper establishes a three-dimensional numerical model simulation and verifies it with physical model experimental results. The crucial parameters affecting the load characteristics of TCC are investigated, including the water blocking rate, area ratio, inclination ratio, inflow velocity, and water temperature stratification ratio. The results show that: (1) This numerical simulation approach can be used to predict the drag coefficient and the load of a TCC; (2) the water blocking rate has the greatest influence on the drag coefficient, and it is the most critical indicator of the TCC load; and (3) the drag coefficient exponentially increases with an increasing water blocking rate, quadratically increases with an increasing area ratio, linearly increases with an increasing inclination ratio, and linearly increases with an increasing water temperature stratification ratio.
    Materialart: Online-Ressource
    ISSN: 2076-3417
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2020
    ZDB Id: 2704225-X
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    In: Nanomaterials, MDPI AG, Vol. 10, No. 6 ( 2020-06-06), p. 1124-
    Kurzfassung: Metallic 1T-phase MoS2 is a newly emerging and attractive catalyst since it has more available active sites and high carrier mobility in comparison with its widely used counterpart of semiconducting 2H-MoS2. Herein, 1T/2H-MoS2(N) (N: MoO3 nanowires were used to prepare 1T/2H-MoS2) was synthesized by using molybdenum trioxide (MoO3) nanowires as the starting material and applied in the photodegradation of antibiotic residue in water. Enhanced photocatalytic performance was observed on the obtained 1T/2H-MoS2(N), which was 2.8 and 1.3 times higher than those on 1T/2H-MoS2(P) (P: commercial MoO3 powder was used to prepare 1T/2H-MoS2) and 2H-MoS2, respectively. The active component responsible for the photodegradation was detected and a reaction mechanism is proposed.
    Materialart: Online-Ressource
    ISSN: 2079-4991
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2020
    ZDB Id: 2662255-5
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    In: Nanomaterials, MDPI AG, Vol. 10, No. 4 ( 2020-03-25), p. 600-
    Kurzfassung: The increasing discharge of dyes and antibiotic pollutants in water has brought serious environmental problems. However, it is difficult to remove such pollutants effectively by traditional sewage treatment technologies. Semiconductor photocatalysis is a new environment-friendly technique and is widely used in aqueous pollution control. TiO2 is one of the most investigated photocatalysts; however, it still faces the main drawbacks of a poor visible-light response and a low charge-separation efficiency. Moreover, powder photocatalyst is difficult to be recovered, which is another obstacle limiting the practical application. In this article, g-C3N4/TiO2 heterojunction is simply immobilized on a glass substrate to form an all-solid-state Z-scheme heterojunction. The obtained thin-film photocatalyst was characterized and applied in the visible-light photodegradation of colored rhodamine B and tetracycline hydrochloride. The photocatalytic performance is related to the deposited layers, and the sample with five layers shows the best photocatalytic efficiency. The thin-film photocatalyst is easy to be recovered with stability. The active component responsible for the photodegradation is identified and a Z-scheme mechanism is proposed.
    Materialart: Online-Ressource
    ISSN: 2079-4991
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2020
    ZDB Id: 2662255-5
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    In: Atmosphere, MDPI AG, Vol. 11, No. 6 ( 2020-06-11), p. 617-
    Kurzfassung: The next generation Hurricane Analysis and Forecast System (HAFS) has been developed recently in the National Oceanic and Atmospheric Administration (NOAA) to accelerate the improvement of tropical cyclone (TC) forecasts within the Unified Forecast System (UFS) framework. The finite-volume cubed sphere (FV3) based convection-allowing HAFS Stand-Alone Regional model (HAFS-SAR) was successfully implemented during Hurricane Forecast Improvement Project (HFIP) real-time experiments for the 2019 Atlantic TC season. HAFS-SAR has a single large 3-km horizontal resolution regional domain covering the North Atlantic basin. A total of 273 cases during the 2019 TC season are systematically evaluated against the best track and compared with three operational forecasting systems: Global Forecast System (GFS), Hurricane Weather Research and Forecasting model (HWRF), and Hurricanes in a Multi-scale Ocean-coupled Non-hydrostatic model (HMON). HAFS-SAR has the best performance in track forecasts among the models presented in this study. The intensity forecasts are improved over GFS, but show less skill compared to HWRF and HMON. The radius of gale force wind is over-predicted in HAFS-SAR, while the hurricane force wind radius has lower error than other models.
    Materialart: Online-Ressource
    ISSN: 2073-4433
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2020
    ZDB Id: 2605928-9
    SSG: 23
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    In: Energies, MDPI AG, Vol. 12, No. 16 ( 2019-08-08), p. 3051-
    Kurzfassung: Stochastic dynamic analysis of an offshore wind turbine (OWT) structure plays an important role in the structural safety evaluation and reliability assessment of the structure. In this paper, the OWT structure is simplified as a linear single-degree-of-freedom (SDOF) system and the corresponding joint probability density function (PDF) of the dynamic response is calculated by the implementation of the path integration (PI) method. Filtered Gaussian white noise, which is obtained from the utilization of a second-order filter, is considered as horizontal wind excitation and used to excite the SDOF system. Thus, the SDOF model and the second-order linear filter model constitute a four-dimensional dynamic system. Further, a detailed three-dimensional finite element model is applied to obtain the natural frequency of the OWT and the efficient PI method, which is modified based on the fast Fourier transform (FFT) convolution method, is also utilized to reduce the execution time to obtain the PDF of the response. Two important parameters of wind conditions, i.e., horizontal mean wind speed and turbulence standard deviation, are investigated to highlight the influences on the PDF of the dynamic response and the reliability of the OWT.
    Materialart: Online-Ressource
    ISSN: 1996-1073
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2019
    ZDB Id: 2437446-5
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Online-Ressource
    Online-Ressource
    MDPI AG ; 2022
    In:  International Journal of Environmental Research and Public Health Vol. 19, No. 15 ( 2022-08-02), p. 9472-
    In: International Journal of Environmental Research and Public Health, MDPI AG, Vol. 19, No. 15 ( 2022-08-02), p. 9472-
    Kurzfassung: The construction of reservoir dams has changed the environment and natural properties of the river course, and deep-water reservoirs present an obvious phenomenon of thermal stratification. Low-temperature outflow water in spring and summer will have a negative impact on the downstream ecological environment. Therefore, it is necessary to take selective withdrawal measures to regulate low-temperature outflow water. The temperature-control curtain project has the advantages of low cost, convenient construction and wide application. Based on the topographic data, a laboratory test model for regulating outflow temperature by a temperature-control curtain is established. A high-power electric heating system is adopted to form a nonlinear thermal stratification. The accuracy of the test data is verified by the prototype observed water temperature. The main parameters affecting the outflow temperature are investigated, including thermal stratification, flow height above the temperature-control curtain, water level, and discharge flow. The results show the following: firstly, the outflow temperature mainly depends on the thermal stratification, decreases with the increase of water level, and increases with the increase of discharge flow; secondly, the effect of a temperature-control curtain on improving the outflow temperature is directly related to the thermal stratification in different months, and the improvement effect is better in spring and summer; finally, the improvement effect increases with the decrease of flow height above the temperature-control curtain, increases with the increase of water level, and decreases with the increase of discharge flow.
    Materialart: Online-Ressource
    ISSN: 1660-4601
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2022
    ZDB Id: 2175195-X
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    Online-Ressource
    Online-Ressource
    MDPI AG ; 2018
    In:  Remote Sensing Vol. 10, No. 5 ( 2018-04-25), p. 666-
    In: Remote Sensing, MDPI AG, Vol. 10, No. 5 ( 2018-04-25), p. 666-
    Materialart: Online-Ressource
    ISSN: 2072-4292
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2018
    ZDB Id: 2513863-7
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    Online-Ressource
    Online-Ressource
    MDPI AG ; 2023
    In:  International Journal of Molecular Sciences Vol. 24, No. 10 ( 2023-05-10), p. 8511-
    In: International Journal of Molecular Sciences, MDPI AG, Vol. 24, No. 10 ( 2023-05-10), p. 8511-
    Kurzfassung: The ammonium transporter (AMT) family gene is an important transporter involved in ammonium uptake and transfer in plants and is mainly engaged in the uptake and transport of ammonium from the environment by roots and the reabsorption of ammonium in the aboveground parts. In this study, the expression pattern, functional identification, and genetic transformation of the PtrAMT1;6 gene, a member of the ammonium transporter protein family in P. trichocarpa, were investigated as follows: (1) Fluorescence quantitative PCR demonstrated that the PtrAMT1;6 gene was preferentially expressed in the leaves, with both dark-induced and light-inhibited expression patterns. (2) A functional restoration assay using the yeast ammonium transporter protein mutant strain indicated that the PtrAMT1;6 gene restored the ability of the mutant to transport ammonium with high affinity. (3) Arabidopsis was transformed with pCAMBIA-PtrAMT1;6P, and the transformed lines were stained with GUS, which showed that the rootstock junction, cotyledon petioles, and the leaf veins and pulp near the petioles of the transformed plants could be stained blue, indicating that the promoter of the PtrAMT1;6 gene had promoter activity. (4) The overexpression of the PtrAMT1;6 gene caused an imbalance in carbon and nitrogen metabolism and reduced nitrogen assimilation ability in ‘84K’ poplar and ultimately reduced biomass. The above results suggest that PtrAMT1;6 may be involved in ammonia recycling during nitrogen metabolism in aboveground parts, and overexpression of PtrAMT1;6 may affect the process of carbon and nitrogen metabolism, as well as nitrogen assimilation in plants, resulting in stunted growth of overexpression plants.
    Materialart: Online-Ressource
    ISSN: 1422-0067
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2023
    ZDB Id: 2019364-6
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    Online-Ressource
    Online-Ressource
    MDPI AG ; 2021
    In:  Sensors Vol. 21, No. 14 ( 2021-07-10), p. 4729-
    In: Sensors, MDPI AG, Vol. 21, No. 14 ( 2021-07-10), p. 4729-
    Kurzfassung: In a traditional antenna array direction finding system, all the antenna sensors need to work or shut down at the same time, which often leads to signal crosstalk, signal distortion, and other electromagnetic compatibility problems. In addition, the direction-finding algorithm in a traditional system needs a tremendous spectral search, which consumes considerable time. To compensate for these deficiencies, a reconfigurable antenna array direction finding system is established in this paper. This system can dynamically load part or all of the antennas through microwave switches (such as a PIN diode) and conduct a fast direction of arrival (DOA) search. First, the hardware structure of the reconfigurable antenna is constructed. Then, based on the conventional spatial domain search algorithm, an improved transform domain (TD) search algorithm is proposed. The effectiveness of the system has been proven by real experiments, and the advantage of the system has been verified by detailed simulations.
    Materialart: Online-Ressource
    ISSN: 1424-8220
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2021
    ZDB Id: 2052857-7
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    Online-Ressource
    Online-Ressource
    MDPI AG ; 2020
    In:  Sensors Vol. 20, No. 7 ( 2020-03-25), p. 1805-
    In: Sensors, MDPI AG, Vol. 20, No. 7 ( 2020-03-25), p. 1805-
    Kurzfassung: The Earth’s ionosphere is greatly influenced by geomagnetic activities, especially geomagnetic storms. During a geomagnetic storm, the ionosphere suffers many perturbations, leading to a spatial gradient that are neglected during geomagnetically quiet periods. An ionospheric gradient generates potential hazards for a ground-based argumentation system (GBAS) by enlarging the errors in the delay corrections between ground monitor stations and users. To address this problem, this work investigates the characteristics of the ionospheric gradient under geomagnetic storms. Global Navigation Satellite System (GNSS) observations from the continuously operating reference station (CORS) network were used to analyze the ionospheric gradients during the geomagnetic storm on 8 September 2017. The statistical behavior of the ionospheric gradient was further discussed. Experiments show that strong geomagnetic perturbations lead to large ionospheric gradients, and the gradients also vary with the geomagnetic location.
    Materialart: Online-Ressource
    ISSN: 1424-8220
    Sprache: Englisch
    Verlag: MDPI AG
    Publikationsdatum: 2020
    ZDB Id: 2052857-7
    Standort Signatur Einschränkungen Verfügbarkeit
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