TY - GEN A1 - Florian, Tobias A1 - Schricker, Klaus A1 - Zenz, Constantin A1 - Otto, Andreas A1 - Schmidt, Leander A1 - Diegel, Christian A1 - Friedmann, Hannes A1 - Seibold, Marc A1 - Hellwig, Peter A1 - Fröhlich, Fabian A1 - Nagel, Falk A1 - Kallage, Peter A1 - Buttazzoni, Michele A1 - Rack, Alexander A1 - Requardt, Herwig A1 - Chen, Yunhui A1 - Bergmann, Jean Pierre T1 - Combining in situ synchrotron X-ray imaging and multiphysics simulation to reveal pore formation dynamics in laser welding of copper T2 - International Journal of Machine Tools and Manufacture N2 - Laser beam welding has emerged as a powerful tool for manufacturing copper components in electrical vehicles, electronic devices or energy storage, owing to its rapid processing capabilities. Nonetheless, the material’s high thermal conductivity and low absorption of infrared light can introduce process instabilities, resulting in defects such as pores. This study employs a hybrid approach that combines in situ synchrotron X-ray imaging with compressible multiphysics process simulation to elucidate pore-forming mechanisms during laser beam welding of copper. High-speed synchrotron X-ray imaging with an acquisition rate of 20,000 images/second facilitates the identification of relevant process regimes concerning pore formation during laser beam welding of copper with a wavelength of 1070 nm. Furthermore, in situ observations with high temporal and spatial resolution present a unique database for extensive validation of a multi-physics process simulation based on welding processes using different concentric intensity distributions. These validated simulation results enable thorough comprehension of process-related pore formation based on the interaction between keyhole, melt pool and resulting flow field. The findings show that pore formation is driven by four different mechanisms: bulging, spiking, upwelling waves at the keyhole rear wall and melt pool ejections. The synergy of high- speed synchrotron X-ray imaging and multi-physics modeling provides a fundamental understanding of the chronological sequence of events leading to process-related pore formation during laser beam welding of copper. KW - In situ high-speed synchrotron X-ray imaging KW - Multi-physics simulation KW - Laser beam welding KW - Copper KW - Pore formation KW - Concentric intensity distributions Y1 - 2025 U6 - https://doi.org/10.1016/j.ijmachtools.2024.104224 SN - 0890-6955 VL - 204 SP - 1 EP - 22 PB - Elsevier BV ER - TY - GEN A1 - Palacio, Juan Camilo Rivera A1 - Bunn, Christian A1 - Rahn, Eric A1 - Little-Savage, Daisy A1 - Schmidt, Paul Günter A1 - Ryo, Masahiro T1 - Geographic-scale coffee cherry counting with smartphones and deep learning T2 - Plant Phenomics N2 - Deep learning and computer vision, using remote sensing and drones, are 2 promising nondestructive methods for plant monitoring and phenotyping. However, their applications are infeasible for many crop systems under tree canopies, such as coffee crops, making it challenging to perform plant monitoring and phenotyping at a large spatial scale at a low cost. This study aims to develop a geographic-scale monitoring method for coffee cherry counting, supported by an artificial intelligence (AI)-powered citizen science approach. The approach uses basic smartphones to take a few pictures of coffee trees; 2,968 trees were investigated with 8,904 pictures in Junín and Piura (Peru), Cauca, and Quindío (Colombia) in 2022, with the help of nearly 1,000 smallholder coffee farmers. Then, we trained and validated YOLO (You Only Look Once) v8 for detecting cherries in the dataset in Peru. An average number of cherries per picture was multiplied by the number of branches to estimate the total number of cherries per tree. The model's performance in Peru showed an R2 of 0.59. When the model was tested in Colombia, where different varieties are grown in different biogeoclimatic conditions, the model showed an R2 of 0.71. The overall performance in both countries reached an R2 of 0.72. The results suggest that the method can be applied to much broader scales and is transferable to other varieties, countries, and regions. To our knowledge, this is the first AI-powered method for counting coffee cherries and has the potential for a geographic-scale, multiyear, photo-based phenotypic monitoring for coffee crops in low-income countries worldwide. Y1 - 2024 U6 - https://doi.org/10.34133/plantphenomics.0165 SN - 2643-6515 VL - 6 PB - American Association for the Advancement of Science (AAAS) ER - TY - GEN A1 - Pożarowska, Emilia A1 - Pleines, Linus A1 - Ewert, Moritz A1 - Prieto, Mauricio J. A1 - Tănase, Liviu Christian A1 - Souza Caldas, Lucas de A1 - Tiwari, Aarti A1 - Schmidt, Thomas A1 - Falta, Jens A1 - Krasovskii, Eugene A1 - Morales, Carlos A1 - Flege, Jan Ingo T1 - Preparation and stability of the hexagonal phase of samarium oxide on Ru(0001) T2 - Ultramicroscopy N2 - We have used low-energy electron microscopy (LEEM), micro-illumination low-energy electron diffraction (µLEED) supported by ab initio calculations, and X-ray absorption spectroscopy (XAS) to investigate in-situ and in real-time the structural properties of Sm2O3 deposits grown on Ru(0001), a rare-earth metal oxide model catalyst. Our results show that samarium oxide grows in a hexagonal A-Sm2O3 phase on Ru(0001), exhibiting a (0001) oriented-top facet and (113) side facets. Upon annealing, a structural transition from the hexagonal to cubic phase occurs, in which the Sm cations exhibit the +3 oxidation state. The unexpected initial growth in the A-Sm2O3 hexagonal phase and its gradual transition to a mixture with cubic C-Sm2O3 showcases the complexity of the system and the critical role of the substrate in the stabilization of the hexagonal phase, which was previously reported only at high pressures and temperatures for bulk samaria. Besides, these results highlight the potential interactions that Sm could have with other catalytic compounds with respect to the here gathered insights on the preparation conditions and the specific compounds with which it interacts. KW - Samarium oxide (Sm2O3) KW - low-energy electron microscopy (LEEM) KW - X-ray photoemission electron microscopy (XPEEM) KW - Facets KW - Epitaxy KW - Hexagonal phase Y1 - 2023 U6 - https://doi.org/10.1016/j.ultramic.2023.113755 SN - 0304-3991 SN - 1879-2723 VL - 250 ER - TY - GEN A1 - Klein, Marten A1 - Zenker, Christian A1 - Starick, Tommy A1 - Schmidt, Heiko T1 - Stochastic modeling of multi-stream mixing based on one-dimensional turbulence T2 - 77th Annual Meeting of the Division of Fluid Dynamics N2 - Measurements of multiple scalar mixing in a turbulent jet show a strong location dependence of the scalar fluctuations and mixing processes. Mixing is quantitatively described by the state space of scalar fluctuations in terms of a joint probability density function (JPDF). The JPDF evolves in the downstream and radial directions and has non-Gaussian shape which is a burden for mixing modeling since factoring into marginal distribution functions is not permissible. Stochastic simulations based on one-dimensional turbulence (ODT) are able to reasonably reproduce the JPDF and its spatial evolution by a parabolic marching problem that circumvents constraints of the underlying elliptic problem. The model reproduces the inertial-advective range (exponent -5/3) and predicts the emergence of the viscous-advective range (exponent -1) at higher wavenumbers as the Schmidt number increases. The model offers full-scale resolution at affordable cost providing means to reasonably capture state-space statistics of turbulent mixing. KW - turbulent mixing KW - one-dimensional turbulence KW - coaxial jet KW - multi-stream mixing Y1 - 2024 UR - https://meetings.aps.org/Meeting/DFD24/Session/ZC40.4 PB - American Physical Society ER - TY - GEN A1 - Klein, Marten A1 - Zenker, Christian A1 - Starick, Tommy A1 - Schmidt, Heiko T1 - Stochastic modeling of multiple scalar mixing in a three-stream concentric coaxial jet based on one-dimensional turbulence T2 - International Journal of Heat and Fluid Flow N2 - Modeling turbulent mixing is a standing challenge for nonpremixed chemically reacting flows. Key complications arise from the requirement to capture all relevant scales of the flow and the necessity to distinguish between turbulent advective transport and molecular diffusive transport processes. In addition, anisotropic mean shear, variable advection time scales, and the coexistence of turbulent and nonturbulent regions need to be represented. The fundamental issues at stake are addressed by investigating multi-scalar mixing in a three-stream coaxial jet with a map-based stochastic one-dimensional turbulence model. ODT provides full-scale resolution at affordable costs by a radical reduction of complexity compared to high-fidelity Navier–Stokes solvers. The approach is partly justified by an application of the boundary-layer approximation, but neglects fluctuating axial pressure gradients. It is demonstrated that low-order scalar statistics are reasonably but not fully captured. Despite this shortcoming, it is shown that the model is able to reproduce experimental state-space statistics of multi-stream multi-scalar mixing. The model therefore offers physics-compatible improvements in multi-stream mixing modeling despite some fundamental limitations that remain from unjustified assumptions. KW - map-based stochastic advection modeling KW - multiple passive scalars KW - one-dimensional turbulence KW - turbulent jet KW - turbulent mixing Y1 - 2023 U6 - https://doi.org/10.1016/j.ijheatfluidflow.2023.109235 SN - 0142-727X N1 - This article is part of the "TSFP12 Special Issue". VL - 104 SP - 1 EP - 17 ER - TY - GEN A1 - Klein, Marten A1 - Starick, Tommy A1 - Zenker, Christian A1 - Medina Méndez, Juan Alí A1 - Schmidt, Heiko T1 - Reduced order stochastic modeling of turbulent mixing based on conservative baker’s maps T2 - Proceedings of the 14th International ERCOFTAC Symposium on Engineering Turbulence Modelling and Measurements (ETMM-14) N2 - The detailed numerical representation of turbulent mixing processes is a standing challenge for non-premixed chemically reacting flows. The full range of relevant flow scales needs to be captured and it is also necessary to distinguish turbulent advective from molecular diffusive processes in order to represent Reynolds and Schmidt number effects. These requirements are addressed here by utilizing two different map-based stochastic turbulence modeling strategies. The one-dimensional turbulence (ODT) model utilizes event-based turbulence modeling, whereas the hierarchical parcel-swapping (HiPS) model is a fully event-based mixing model. ODT provides full-scale resolution at affordable costs by dimensional model reduction based on the boundary-layer approximation to shear flow. HiPS is far less costly than ODT but currently limited to locally homogeneous isotropic turbulence. The physics-compatible modeling capabilities with respect to phase-space representation of turbulent mixing are demonstrated for two canonical cases using standalone model formulations. KW - turbulent mixing KW - one-dimensional turbulence (ODT) KW - hierarchical parcel swapping (HiPS) KW - stochastic turbulence modeling KW - round jet KW - passive scalar Y1 - 2023 UR - https://etmm.ercoftac.org/etmm/program/conference-program/ UR - https://drive.google.com/file/d/1q2BDOO5bXfqq0Y4z4HCGndiFI033bPyg/view?usp=drive_link SP - 613 EP - 618 PB - ERCOFTAC CY - Barcelona, Spain ER - TY - GEN A1 - Diegel, Christian A1 - Schricker, Klaus A1 - Schmidt, Leander A1 - Seibold, Marc A1 - Friedmann, Hannes A1 - Hellwig, Peter A1 - Fröhlich, Fabian A1 - Nagel, Falk A1 - Kallage, Peter A1 - Rack, Alexander A1 - Requardt, Herwig A1 - Chen, Yunhui A1 - Bergmann, Jean Pierre T1 - In situ characterization of keyhole behavior and spatter formation in full penetration laser beam welding with local gas flow using high-speed synchrotron X-ray imaging T2 - Optics & laser technology N2 - Spatter formation is a major issue at welding speeds above 8 m/min for full penetration laser beam welding of high-alloyed steels. In experiments using a local gas flow directed at the keyhole rear wall, a reduction in spatter formation on the specimen top side was observed for welding of AISI 304. However, the interaction between gas flow and keyhole behavior with respect to the mechanisms and locations of spatter detachment, especially on the bottom side, is not yet fully understood. High-speed synchrotron X-ray imaging enables detailed insights into the keyhole behavior and the spatter formation to obtain a deeper understanding of the underlying mechanisms. During the reference experiments welding without shielding gas flow, the spatter detach from a melt pool swelling behind the keyhole aperture on both sides of the sheet. A gas flow with a low flow rate of 4.8 L/min reduces the spatter formation on the top side and the keyhole length due to the absence of oxygen affecting the surface tension. A swelling also forms on the keyhole front on the bottom side and small spatter detach undirected. Increasing the flow rate to 12.8 L/min elongates the keyhole, particularly on the specimen top side. The increased momentum transfer of the gas flow results in a periodic keyhole oscillation on the specimen top side. In combination with an elongated melt pool, the oscillation is directly correlated with the hump formation, caused by melt being pushed over the already solidified weld seam. In addition, spatter does not detach from the top side due to the changed melt flow and only detach from the keyhole front on the bottom side. KW - Laser welding KW - Spatter formation KW - Gas flow KW - High-speed X-ray imaging KW - Synchrotron KW - In situ Y1 - 2025 U6 - https://doi.org/10.1016/j.optlastec.2025.113367 SN - 0030-3992 VL - 191 SP - 1 EP - 17 PB - Elsevier BV CY - Amsterdam ER - TY - CHAP A1 - Ulrich, Rainer G. A1 - Schlegel, Matthias A1 - Mertens, Marc A1 - Groschup, Martin H. A1 - Schmidt-Chanasit, Jonas A1 - Plenge-Bönig, Anita A1 - Jacob, Jens A1 - Pelz, Hans-Joachim A1 - Freise, Jona A1 - Wenk, Matthias A1 - Thiel, Jörg A1 - Triebenbacher, Cornelia A1 - Schmolz, Eric A1 - Kurth, Andreas A1 - Krüger, Frank A1 - Rühe, Ferdinand A1 - Kiffner, Christian A1 - Ansorge, Hermann A1 - Gerwin, Werner A1 - Wegener, Wolfgang A1 - Müller, Jörg A1 - Bemmann, Margit A1 - Wolf, Ronny A1 - Otto, Lutz-Florian A1 - Oehme, Rainer A1 - Pfeffer, Martin A1 - Heckel, Gerald A1 - Schex, Susanne A1 - Essbauer, Sandra S. T1 - Netzwerk Nagetier-übertragene Pathogene: Monitoring von Hantavirus-Infektionen in Deutschland T2 - Wildhygiene, Wildtierkrankheiten, Parasiten, Epidemiologie Y1 - 2009 SN - 978-378-88131-2-3 SN - 1436-3895 SP - 229 EP - 250 PB - Ges. für Wildtier- und Jagdforschung CY - Halle/Saale ER - TY - GEN A1 - Veldkamp, Edzo A1 - Schmidt, Marcus A1 - Markwitz, Christian A1 - Beule, Lukas A1 - Beuschel, René A1 - Biertümpfel, Andrea A1 - Bischel, Xenia A1 - Duan, Xiaohong A1 - Gerjets, Rowena A1 - Göbel, Leonie A1 - Graß, Rüdiger A1 - Guerra, Victor A1 - Heinlein, Florian A1 - Komainda, Martin A1 - Langhof, Maren A1 - Luo, Jie A1 - Potthoff, Martin A1 - Ramshorst, Justus G. V. van A1 - Rudolf, Carolin A1 - Seserman, Diana-Maria A1 - Shao, Guodong A1 - Siebicke, Lukas A1 - Svoboda, Nikolai A1 - Swieter, Anita A1 - Carminati, Andrea A1 - Freese, Dirk A1 - Graf, Torsten A1 - Greef, Jörg M. A1 - Isselstein, Johannes A1 - Jansen, Martin A1 - Karlovsky, Petr A1 - Knohl, Alexander A1 - Lamersdorf, Norbert A1 - Priesack, Eckart A1 - Wachendorf, Christine A1 - Wachendorf, Michael A1 - Corre, Marife D. T1 - Multifunctionality of temperate alley-cropping agroforestry outperforms open cropland and grassland T2 - Communications Earth & Environment N2 - AbstractIntensively managed open croplands are highly productive but often have deleterious environmental impacts. Temperate agroforestry potentially improves ecosystem functions, although comprehensive analysis is lacking. Here, we measured primary data on 47 indicators of seven ecosystem functions in croplands and 16 indicators of four ecosystem functions in grasslands to assess how alley-cropping agroforestry performs compared to open cropland and grassland. Carbon sequestration, habitat for soil biological activity, and wind erosion resistance improved for cropland agroforestry (P ≤ 0.03) whereas only carbon sequestration improved for grassland agroforestry (P < 0.01). In cropland agroforestry, soil nutrient cycling, soil greenhouse gas abatement, and water regulation did not improve, due to customary high fertilization rates. Alley-cropping agroforestry increased multifunctionality, compared to open croplands. To ameliorate the environmental benefits of agroforestry, more efficient use of nutrients is required. Financial incentives should focus on conversion of open croplands to alley-cropping agroforestry and incorporate fertilizer management. Y1 - 2023 U6 - https://doi.org/10.1038/s43247-023-00680-1 SN - 2662-4435 VL - 4 IS - 1 PB - Springer Science and Business Media LLC ER - TY - CHAP A1 - Bärwolff, Manuela A1 - Böhm, Christian A1 - Schmidt, C. A1 - Schwarz, K.- U. A1 - Vetter, A. T1 - Combining short rotation coppice with annual crops - modern agroforestry systems for sustainable land use T2 - Proceedings of the 19th European Biomass Conference and Exhibition: From Research to Industry and Markets, 6-9 Juni 2011 in Berlin, Deutschland Y1 - 2011 SN - 978-88-89407-55-4 U6 - https://doi.org/10.5071/19thEUBCE2011-OB1.5 SP - 55 EP - 60 ER - TY - CHAP A1 - Grünewald, Holger A1 - Bärwolff, Manuela A1 - Böhm, Christian A1 - Schwarz, K.- U. A1 - Schmidt, C. T1 - Ökologische und ökonomische Bewertung von Agroforstsystemen in der landwirtschaftlichen Praxis T2 - Holzerzeugung in der Landwirtschaft Y1 - 2008 SN - 978-3-937728-05-6 N1 - Verbundforschungsvorhaben DENDROM SP - 213 EP - 216 PB - BTU CY - Cottbus ER - TY - CHAP A1 - Böhm, Christian A1 - Freese, Dirk A1 - Schmidt, C. A1 - Hüttl, Reinhard F. T1 - Alley cropping - an option to combine crop and woody biomass production at degraded post-mining sites in Germany T2 - Book of Abstracts, 2nd World Congress of Agroforestry, Agroforestry - The Future of Global Land Use Y1 - 2009 UR - http://www.worldagroforestry.org/wca2009/reports/docs/Book%20of%20Abstracts-Final%20with%20Index%20new.pdf SN - 978-92-9059-255-6 SP - S. 253 PB - World Agroforestry Centre CY - Nairobi, Kenya ER - TY - CHAP A1 - Grünewald, Holger A1 - Bärwolff, Manuela A1 - Böhm, Christian A1 - Schwarz, K.- U. A1 - Schmidt, C. T1 - Establishment of alley-cropping systems with short rotation woody crops in Germany T2 - Book of Abstracts, 2nd World Congress of Agroforestry, Agroforestry - The Future of Global Land Use Y1 - 2009 UR - http://www.worldagroforestry.org/wca2009/reports/docs/Book%20of%20Abstracts-Final%20with%20Index%20new.pdf SN - 978-92-9059-255-6 SP - S. 119 PB - World Agroforestry Centre CY - Nairobi, Kenya ER - TY - GEN A1 - Schricker, Klaus A1 - Schmidt, Leander A1 - Nagel, Falk A1 - Diegel, Christian A1 - Friedmann, Hannes A1 - Seibold, Marc A1 - Hellwig, Peter A1 - Fröhlich, Fabian A1 - Kallage, Peter A1 - Chen, Yunhui A1 - Requardt, Herwig A1 - Rack, Alexander A1 - Bergmann, Jean Pierre T1 - A comprehensive study on the influence of spatial power distribution on time-dependent keyhole behavior in laser beam welding of copper by means of high-speed synchrotron X-ray imaging T2 - Optics & laser technology N2 - This paper examines the impact of spatial power distributions on the time-dependent keyhole behavior during laser beam welding of copper using high-speed synchrotron X-ray imaging. The experimental setup utilized a COHERENT HighLight FL8000-ARM fiber laser with concentric intensity distribution created by an optical fiber cable. The European Synchrotron Radiation Facility (ESRF, beamline ID19) was used to conduct high-speed synchrotron imaging at 20,000 images per second to study the spatio-temporal keyhole behavior. Keyhole geometries were extracted through advanced image processing techniques, allowing quantification of parameters like depth, aperture, bulging, and determination of related oscillation frequencies. The results showed that core-dominated processes exhibit significant variations in keyhole geometry. In contrast, ring-dominated processes exhibited reduced penetration depths but increased melt pool dynamics due to altered absorption conditions and increased temperatures within the melt pool. A stabilized core-ring power distribution minimized fluctuations, resulting in improved process stability. The findings were summarized in a model concept describing three characteristic keyhole regimes: core-dominated, ring-dominated, and stabilized core-ring processes. KW - Laser welding KW - Synchrotron KW - In situ KW - Copper KW - Intensity, spatial power distribution Y1 - 2025 U6 - https://doi.org/10.1016/j.optlastec.2025.113999 SN - 0030-3992 VL - 192, Part E SP - 1 EP - 15 PB - Elsevier BV CY - Amsterdam ER - TY - GEN A1 - Balas, Johannes A1 - Urbank, Christian A1 - Kaden, Peter A1 - Patzschke, Michael A1 - März, Juliane A1 - Kvashnina, Kristina O. A1 - Schmidt, Moritz A1 - Stumpf, Thorsten A1 - Gericke, Robert T1 - Bonding trends in pyridine-2-thiolato complexes of tetravalent actinides T2 - Inorganic chemistry N2 - Complexes of tetravalent actinides (An: Th, U, Np, Pu) with the bidentate (N,S)-donor ligand pyridine-2-thiolate (2-PyS, PyS−) were synthesized in 1:4 or 1:5 ratios. This includes the first structurally characterized Np complex with (N,S)-donor ligands, filling a notable gap in An coordination chemistry. An improved synthetic approach with PyS–SiMe3 enabled efficient formation of the 1:4 complexes in THF as coordinating solvent. The compounds were comprehensively characterized in solution and in solid phase, supported by quantum chemical calculations. Experimental and theoretical results show matching trends in the binding behavior of AnIV. The covalent bond contributions in An–N and An–S bonding increase along the series of An from Th to Pu. The bonds to the soft sulfur donors consistently have the highest covalent contributions with a remarkably high percentage for Pu–S (IQA analysis: >34%) over the harder N donors or An–O bonds of coordinating THF. High-resolution X-ray absorption and infrared spectroscopy indicate similar electronic and structural properties across AnIV complexes, while SQUID magnetometry uncovered significant differences in magnetic behavior at low temperatures depending on the complex compositions. This work advances the understanding of An-ligand bonding, emphasizing covalency and electronic structures, and expands fundamental insights into An chemistry. KW - Actinides KW - Single-crystal X-ray diffraction KW - Bonding trends KW - HERFD-XANES KW - SQUID Y1 - 2025 U6 - https://doi.org/10.1021/acs.inorgchem.5c03369 SN - 1520-510X VL - 64 IS - 44 SP - 21919 EP - 21931 PB - American Chemical Society CY - Washington, DC ER -