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Rigorous 3D modeling of confocal microscopy on 2D surface topographies
(2021-06-07)
Although optical 3D topography measurement instruments are widespread, measured profiles suffer from systematic deviations occurring due to the wave characteristics of light. These deviations can be analyzed by numerical simulations. We present a 3D modeling of the image formation of confocal microscopes. For this, the light-surface interaction is simulated using two different rigorous methods, the finite element method and the rigorous coupled-wave analysis. The image formation in the confocal microscope is simulated ...
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On the Intergranular Corrosion Properties of Thin Ferritic Stainless Steel Sheets Welded by Fiber-Laser
(2020-08-12)
In the present investigation, thin sheets of stabilized and unstabilized ferritic stainless steel were welded in butt joint configuration using irradiation of a 1070 nm fiber-laser. Using optical microscopy, the microstructural evolution upon alternating heat input was characterized. In addition to that, hardness and tensile tests were carried out on the specimens. Detailed focus was given to the intergranular corrosion properties, which were investigated on basis of the Strauss test with different times of exposure ...
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Performance of field-scale lab vs in situ visible/near- and mid-infrared spectroscopy for estimation of soil properties
(2021-10-10)
Comparison of laboratory versus in situ visible/near- (visNIR) and mid-infrared (MIR) spectroscopy for prediction of various soil properties is required to demonstrate trade-offs between accuracy and efficiency. Field measurements were made on an arable field in Germany (silt loam Haplic Luvisol) using visNIR (ASD FieldSpec 3 Hi-Res) and MIR (Agilent Technologies 4300 Handheld FTIR) and material was collected for lab visNIR (Foss XDS Rapid Content Analyzer) and MIR (Bruker-TENSOR 27) measurements on dried and ground ...
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On the Influence of Microstructure on the Corrosion Behavior of Fe–Mn–Al–Ni Shape Memory Alloy in 5.0 wt% NaCl Solution
(2020-10-03)
Herein the corrosion behavior of Fe–Mn–Al–Ni shape memory alloys characterized by different microstructures in a 5.0 wt% NaCl solution is investigated. Open circuit potential and potentiodynamic polarisation tests are conducted. Generally, Fe–Mn–Al–Ni shows corrosion properties being similar to pure iron. However, the polarization curves of single crystals indicate the presence of an unstable passive system. The corrosion damage is analyzed by means of optical microscopy and electron microscopy. It is revealed that ...
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A Novel Approach to Inhibit Intergranular Corrosion in Ferritic Stainless Steel Welds Using High-Speed Laser Cladding
(2021-12-15)
Ferritic stainless steels are prone to localized corrosion phenomena such as pitting corrosion or intergranular corrosion, in particular when jointed by fusion welding processes. State-of-the-art techniques to avoid intergranular corrosion mainly consist of alternating alloy concepts or post-weld heat-treatments—all of which are associated with increased production costs. Hence, the present investigation seeks to introduce a novel approach for the inhibition of intergranular corrosion in ferritic stainless steel welds ...
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Translatory and rotatory motion of exchange-bias capped Janus particles controlled by dynamic magnetic field landscapes
(2021-11-08)
Magnetic Janus particles (MJPs), fabricated by covering a non-magnetic spherical particle with a hemispherical magnetic in-plane exchange-bias layer system cap, display an onion magnetization state for comparably large diameters of a few microns. In this work, the motion characteristics of these MJPs will be investigated when they are steered by a magnetic field landscape over prototypical parallel-stripe domains, dynamically varied by superposed external magnetic field pulse sequences, in an aqueous medium. We ...
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Design based on availability: Generative design and robotic fabrication workflow for non-standardized sheet metal with variable properties
(2022-03-07)
This paper presents the use of a computational design algorithm in combination with robotic fabrication and sensing to augment the design and construction process for non-standardized material. Although reusing reclaimed material can significantly reduce the environmental impact in building construction, current design processes are not set up for this shift in thinking. Contrary to conventional practices, designing within the constraints of available material means that geometry and topology cannot be fully ...
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3DWoodWind: robotic winding processes for material-efficient lightweight veneer components
(2022-03-25)
Winding processes are known from fiber composite technology for highly resistance lightweight components for aviation. These fiber-based processes work predominantly with synthetic composites made of carbon or glass fibers. For the construction industry, these additive processes are very promising and resource-efficient building processes, but they are still hardly used in timber construction despite the very high level of digitalization and technical development. The 3DWoodWind research project uses a continuous ...
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Additive surface texturing of cutting tools using pulsed laser implantation with hard ceramic particles
(2020-09-15)
In recent years surface texturing of the cutting tools has proved to improve tribological characteristics at tool/chip and tool/workpiece interface and help to reduce cutting and feed forces as well as tool wear. Most, if not all, of the studies have focused on subtractively made textures whereby the material is removed from the surface. This study investigates the performance of additively made surface structures whereby hard ceramic particles are dispersed in the form of dome shaped textures on the surface of the ...
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Influence of Surface Roughness on Pressure Drop in Two‐Phase Flow of Saturated Hydrocarbons
(2019-12-19)
Pressure drop of propane and propylene in gas‐liquid saturation state are investigated for copper and mild steel test tubes. The surface structure of both tubes is determined with the focus variation method, yielding a six times higher roughness for the steel tube, although both tubes are manufactured in the same manner. In both tubes single phase pressure drop validation measurements are carried out and compared to known correlations. For two‐phase investigations both fluids are investigated at the reduced saturation ...