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Keywords = UVRT

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15 pages, 5867 KB  
Article
Impact of Hydrocarbon Emissions from Oil and Gas Deposits on δ13C Variability in Pine Tree Rings from the Tatarstan Republic
by Olga V. Churakova (Sidorova), Georgii Batalin, Bulat Gareev, Gazinur Mingazov, Andrey Terekhin, Denis Tishin, Dilyara Kuzina and Danis Nurgaliev
Forests 2023, 14(10), 2093; https://doi.org/10.3390/f14102093 - 18 Oct 2023
Viewed by 2010
Abstract
Human-caused anthropogenic greenhouse emissions impact the climate globally. In this pilot study, we aim to reveal the influence of hydrocarbon emissions on pine forests by applying a stable carbon isotope analysis in pine tree rings (δ13Cptrw). Our study was [...] Read more.
Human-caused anthropogenic greenhouse emissions impact the climate globally. In this pilot study, we aim to reveal the influence of hydrocarbon emissions on pine forests by applying a stable carbon isotope analysis in pine tree rings (δ13Cptrw). Our study was conducted in an industrial giant oil field reservoir (UVRT) and natural reserve (Raifa) sites, the Tatarstan Republic, Russia. Our results show a decreasing δ13Cptrw at the UVRT site in 1943, when oil extraction started, and in 1970, when it reached maximum production. We found that the δ13Cptrw from UVRT indicates developing unfavourable drier conditions and a suppressed tree growth caused by both human-induced oil and deposit infrastructures and natural processes compared to the undisturbed Raifa site. A 5-year running correlation analysis showed a significant difference between the sites in 1965 over the period of 1930 to 2021. The δ13Cptrw values from Raifa are more negative compared to UVRT, which can be explained by a higher forest sensitivity to human-induced impacts. From an eco-physiological point of view, the decreasing of intercellular (ci)-to-ambient (ca) CO2 concentration ratios at the leaf level and the increasing of intrinsic water-use efficiency (iWUE) along with a decreasing of tree-ring widths at the UVRT site (1970–2021) indicate the development of drought conditions. Full article
(This article belongs to the Special Issue Response of Tree Rings to Climate Change and Climate Extremes)
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18 pages, 7035 KB  
Article
Validation of Wind Turbine Models Based on Test Bench Measurements: A System for Theoretical Representation of the Grid Replica
by Anica Frehn, Jens Sdun, Rayk Grune and Antonello Monti
Wind 2023, 3(3), 302-319; https://doi.org/10.3390/wind3030018 - 26 Jul 2023
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Abstract
In recent years, nacelle test benches for wind turbines have been developed internationally. New standards are currently being developed that explicitly refer to the measurement of the electrical properties of wind turbines on these test benches. Thus, they are suitable for measuring the [...] Read more.
In recent years, nacelle test benches for wind turbines have been developed internationally. New standards are currently being developed that explicitly refer to the measurement of the electrical properties of wind turbines on these test benches. Thus, they are suitable for measuring the electrical properties required for certification. Another part of the certification is the creation and validation of suitable models of the wind turbine, which are used for stability analyses of the utility grid. Validation requires a suitable model of grid replication on the test benches, which is not yet covered by any applicable standard. Such models should be as simplified a representation of the artificial grid replication as possible to ensure that they are accessible to certification bodies. A model of the grid emulator installed at the CWD of RWTH Aachen University, which was validated with real measurement data, serves as a reference. A step-by-step reduction of the model’s depth up to the system’s technical representation is followed by a model evaluation with respect to the level of detail and an analysis of time and frequency. The evaluation shows that even a highly simplified model consisting of a reference voltage and an impedance replica meets the requirements for the validation of wind turbine models according to IEC 61400-27-2. Full article
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