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- ItemAssessment of Subsampling Strategies in Microspectroscopy of Environmental Microplastic Samples(Lausanne : Frontiers Media, 2021) Brandt, Josef; Fischer, Franziska; Kanaki, Elisavet; Enders, Kristina; Labrenz, Matthias; Fischer, DieterThe analysis of environmental occurrence of microplastic (MP) particles has gained notable attention within the past decade. An effective risk assessment of MP litter requires elucidating sources of MP particles, their pathways of distribution and, ultimately, sinks. Therefore, sampling has to be done in high frequency, both spatially and temporally, resulting in a high number of samples to analyze. Microspectroscopy techniques, such as FTIR imaging or Raman particle measurements allow an accurate analysis of MP particles regarding their chemical classification and size. However, these methods are time-consuming, which gives motivation to establish subsampling protocols that require measuring less particles, while still obtaining reliable results. The challenge regarding the subsampling of environmental MP samples lies in the heterogeneity of MP types and the relatively low numbers of target particles. Herein, we present a comprehensive assessment of different proposed subsampling methods on a selection of real-world samples from different environmental compartments. The methods are analyzed and compared with respect to resulting MP count errors, which eventually allows giving recommendations for staying within acceptable error margins. Our results are based on measurements with Raman microspectroscopy, but are applicable to any other analysis technique. We show that the subsampling-errors are mainly due to statistical counting errors (i.e., extrapolation from low numbers) and only in edge cases additionally impacted by inhomogeneous distribution of particles on the filters. Keeping the subsampling-errors low can mainly be realized by increasing the fraction of MP particles in the samples.
- ItemPressure-based lift estimation and its application to feedforward load control employing trailing-edge flaps(Göttingen : Copernicus Publications, 2021) Bartholomay, Sirko; Wester, Tom T. B.; Perez-Becker, Sebastian; Konze, Simon; Menzel, Christian; Hölling, Michael; Spickenheuer, Axel; Peinke, Joachim; Nayeri, Christian N.; Paschereit, Christian Oliver; Oberleithner, KilianThis experimental load control study presents results of an active trailing-edge flap feedforward controller for wind turbine applications. The controller input is derived from pressure-based lift estimation methods that rely either on a quasi-steady method, based on a three-hole probe, or on an unsteady method that is based on three selected surface pressure ports. Furthermore, a standard feedback controller, based on force balance measurements, is compared to the feedforward control. A Clark-Y airfoil is employed for the wing that is equipped with a trailing-edge flap of chordwise extension. Inflow disturbances are created by a two-dimensional active grid. The Reynolds number is Re=290 000, and reduced frequencies of k=0.07 up to k=0.32 are analyzed. Within the first part of the paper, the lift estimation methods are compared. The surface-pressure-based method shows generally more accurate results, whereas the three-hole probe estimate overpredicts the lift amplitudes with increasing frequencies. Nonetheless, employing the latter as input to the feedforward controller is more promising as a beneficial phase lead is introduced by this method. A successful load alleviation was achieved up to reduced frequencies of k=0.192.
- ItemCorrigendum to "A Versatile Surface Bioengineering Strategy Based on Mussel-Inspired and Bioclickable Peptide Mimic"([Beijing] : China Association for Science and Technology, 2021) Xiao, Yu; Wang, Wenxuan; Tian, Xiaohua; Tan, Xing; Yang, Tong; Gao, Peng; Xiong, Kaiqing; Tu, Qiufen; Wang, Miao; Maitz, Manfred F.; Huang, Nan; Pan, Guoqing; Yang, Zhilu[This corrects the article DOI: 10.34133/2020/7236946.].