ORCID Profile
0000-0002-5538-8431
Current Organisations
University of Bayreuth
,
University of Oxford
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Publisher: Elsevier BV
Date: 06-2021
Publisher: Elsevier BV
Date: 04-2021
Publisher: Springer Science and Business Media LLC
Date: 10-12-2019
Publisher: AIP Publishing
Date: 28-03-2012
DOI: 10.1063/1.3694656
Abstract: Bulk ion toroidal rotation plays a critical role in controlling microturbulence and MHD stability as well as yielding important insight into angular momentum transport and the investigation of intrinsic rotation. So far, our understanding of bulk plasma flow in hydrogenic plasmas has been inferred from impurity ion velocity measurements and neoclassical theoretical calculations. However, the validity of these inferences has not been tested rigorously through direct measurement of the main-ion rotation in deuterium plasmas, particularly in regions of the plasma with steep pressure gradients where very large differences can be expected between bulk ion and impurity rotation. New advances in the analysis of wavelength-resolved Dα emission on the DIII-D tokamak [J. L. Luxon et al., Fusion Sci. Technol. 48, 807 (2002)] have enabled accurate measurements of the main-ion (deuteron) temperature and toroidal rotation. The Dα emission spectrum is accurately fit using a model that incorporates thermal deuterium charge exchange, beam emission, and fast ion Dα (FIDA) emission spectra. Simultaneous spectral measurements of counter current injected and co current injected neutral beams permit a direct determination of the deuterium toroidal velocity. Time-dependent collisional radiative modeling of the photoemission process is in quantitative agreement with measured spectral characteristics. L-mode discharges with low beam ion densities and broad thermal pressure profiles exhibit deuteron temperature and toroidal rotation velocities similar to carbon. However, intrinsic rotation H-mode conditions and plasmas with internal transport barriers exhibit differences between core deuteron and carbon rotation which are inconsistent with the sign and magnitude of the neoclassical predictions.
Publisher: AIP Publishing
Date: 02-2011
DOI: 10.1063/1.3553394
Abstract: Charge exchange spectroscopy is one of the standard plasma diagnostic techniques used in tokamak research to determine ion temperature, rotation speed, particle density, and radial electric field. Configuring a charge coupled device (CCD) camera to serve as a detector in such a system requires a trade-off between the competing desires to detect light from as many independent spatial views as possible while still obtaining the best possible time resolution. High time resolution is essential, for ex le, for studying transient phenomena such as edge localized modes. By installing a mask in front of a camera with a 1024 × 1024 pixel CCD chip, we are able to acquire spectra from eight separate views while still achieving a minimum time resolution of 0.2 ms. The mask separates the light from the eight spectra, preventing spatial and temporal cross talk. A key part of the design was devising a compact translation stage which attaches to the front of the camera and allows adjustment of the position of the mask openings relative to the CCD surface. The stage is thin enough to fit into the restricted space between the CCD camera and the spectrometer endplate.
Publisher: MDPI AG
Date: 27-03-2019
DOI: 10.3390/SOILSYSTEMS3020023
Abstract: Fungi and bacteria play a central role in the cycling of carbon (C) and nitrogen (N), which has been frequently assessed by manipulating their abundance in soil with the application of fungicides and bactericides. We conducted a meta-analysis using 61 publications to investigate whether fungicides and bactericides have distinct effects on soil C- and N- cycling, and how they vary with land type and soil properties. Most fungicides and bactericides had significant negative effects on microbial biomass C and N. However, they had mixed effects on soil respiration, N pools, and transformation processes, varying strongly with the type of fungicide and bactericide. Available NO3− was lightly affected, while N2O emission was reduced by most biocides. The application of fungicides had neutral effects on respiration, NH4+, and ammonification in agro-ecosystems, but positive effects in forests. Effect sizes of available NO3− and nitrification in response to bactericides were sensitive to soil pH and C content. Our results suggest that most fungicides and bactericides inhibit microbial growth, but that they have mixed effects on respiration and N cycling. Biocides need to be carefully evaluated for unintentional side effects before they are used in assessing the role of fungi and bacteria for C- and N- cycling.
Publisher: Elsevier BV
Date: 04-2021
Publisher: Frontiers Media SA
Date: 05-06-2023
DOI: 10.3389/FEVO.2023.1152955
Abstract: Forest spatial structures are the foundations of the structure and function of forest ecosystems. Quantitative descriptions and analyses of forest spatial structure have recently become common tools for digitalized forest management. Therefore, the accuracy and intelligence of acquiring forest spatial structure information are of great significance. In this study, we developed a forest measurement system using a mobile phone. Through this system, the following tree measurements can be achieved: (1) point cloud of tree and chest diameter circle to measure tree diameter at breast height (DBH) and position coordinates of tree by using simultaneous localization and mapping (SLAM) technology, (2) virtual boundary creation of the s le plot, and the auxiliary measurement function of tree with the augmented reality (AR) interactive module, and (3) position coordinates and single-tree volume factor to calculate the spatial structural parameters of the forest (e.g., Mingling degree, Dominance index, Uniform angle index, and Crowdedness index).The system was tested in three 32 x 32 martificial forest plots. The average DBH estimations showed BIAS of -0.47 to 0.45 cm and RMSEs of 0.57 to 0.95 cm. Its accuracy level met the requirements of forestry s le surveys. The tree position estimates for the three plots had relatively small RMSEs with 0.17 to 0.22 m on the x-axis and 0.16 to 0.26 m on the y-axis. The spatial structural parameters were as follows: the mingling degree of plot 1 was 0.32, and the overall mixing degree of tree species was low. The trees in plots 2 and 3 were all single species, and the mixing degree of both plots was 0. The dominance index of the three plots was 0.56, 0.51, and 0.51, indicating that the competitive advantage of the whole orest species was not obvious. The uniform angle index of the three plots was 0.55, 0.59, and 0.61, indicating that the positions of trees in the three plots were randomly distributed. The crowdedness index of plot 1 was 1.03, indicating that the degree of aggregation of the trees was low and showed a random distribution trend. The crowdedness index of the other plots were 1.36 and 1.40, indicating that the trees in the plots show a trend of uniform distribution, and the uniformity of plot 3 is higher than that of plot 2, but the overall uniformity is relatively weak. The findings of this study provide support for the optimization of forest structures and improve our conceptual understanding of forest community succession and restoration, in addition to the informatization and precision of forest spatial structure surveys.
Publisher: Elsevier BV
Date: 11-2012
Location: Bangladesh
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Michael Suttie.