The geometric calibration of cameras becomes necessary when images should be undistorted, geometric image information is needed or data from more than one camera have to be fused. This process is often done using a target with a checkerboard or circular pattern and a given geometry. In this work, a coded checkerboard target for thermal imaging cameras and the corresponding image processing algorithm for iterative feature detection are presented. It is shown that, due in particular to the resulting better feature ...

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 ...

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 ...

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 ...

Hops are critical to the brewing industry. In commercial hop drying, a large bulk of hops is dried in multistage kilns for several hours. This affects the drying behavior and alters the amount and chemical composition of the hop oils. To understand these changes, hops of the var. Hallertauer Tradition were dried in bulks of 15, 25 and 35 kg/m² at 60 °C and 0.35 m/s. Additionally, bulks of 25 kg/m² were also dried at 65 °C and 0.45 m/s to assess the effect of change in temperature and velocity, respectively. The results ...

This study aimed to understand the influence of extruded microparticulated whey proteins (eMWPs) and process design in light ice cream processing by evaluating the microstructure and physicochemical properties. The inulin (T1), a commercial microparticulated whey protein (MWP) called simplesse (T2), a combination (T3), as well as eMWPs (as 50% volume of total particles): d50 < 3 µm (T4), and d50 > 5 µm (T5) were used as fat replacers. The first process design was pasteurization with subsequent homogenization (PH). ...

The focus of this study is on the characterization of the local plastic deformation and failure of functionally graded 22MnB5 plates after hot stamping using an in situ approach. Various forming strategies at elevated temperatures are performed using differentially tempered forming tools to locally tailor the microstructure. By controlling the cooling rate, graded as well as martensitic and ferritic–pearlitic microstructures are obtained. Experimental analysis includes evaluation of the material- and geometry-dependent ...

Three-dimensional (3D) transfer functions build the basis for a comprehensive characterization of optical imaging systems in the spatial frequency domain. Utilizing the projection-slice theorem, the 2D modulation transfer function of an incoherent imaging system can be derived from a 3D transfer function by integration with respect to the axial spatial frequency. For a diffraction limited microscope with homogeneous incoherent pupil illumination, the modulation transfer function equals the 2D autocorrelation function ...

In this study, the relationship between a person’s walking speed and the perception threshold for discrete implicit repositioning during eyeblinks in a virtual environment is investigated. The aim is to estimate the perception thresholds for forward and backward repositioning during forward translation following eyeblink occurrences. A psychophysical method called Staircase Transformed and Weighted up/down is utilized to quantify the perception thresholds for forward and backward repositioning. The perception thresholds ...

We present a numerical investigation on the detection of superparamagnetic labels using a giant magnetoresistance (GMR) vortex structure. For this purpose, the Landau–Lifshitz–Gilbert equation was solved numerically applying an external z-field for the activation of the superparamagnetic label. Initially, the free layer’s magnetization change due to the stray field of the label is simulated. The electric response of the GMR sensor is calculated by applying a self-consistent spin-diffusion model to the precomputed ...