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Optical Quality of InAs/InP Quantum Dots on Distributed Bragg Reflector Emitting at 3rd Telecom Window Grown by Molecular Beam Epitaxy
(2021-10-21)
We present an experimental study on the optical quality of InAs/InP quantum dots (QDs). Investigated structures have application relevance due to emission in the 3rd telecommunication window. The nanostructures are grown by ripening-assisted molecular beam epitaxy. This leads to their unique properties, i.e., low spatial density and in-plane shape symmetry. These are advantageous for non-classical light generation for quantum technologies applications. As a measure of the internal quantum efficiency, the discrepancy ...
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Force distribution in self-tapping screws: experimental investigations with fibre Bragg grating measurement screws
(2021-08-17)
The pull-out resistance of fully threaded, self-tapping screws under axial loading has been investigated intensively in the past. Actual design models are based mainly on empirical data because the detailed interaction between the screw thread and the surrounding timber member remains unclear and might depend on the test set-up. An innovative screw sensor with 19 internal fibre Bragg gratings (FBGs) was developed to measure the forces along the screw axis. The screw diameter was 12 mm and the maximum embedding length ...
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Characterization of Mechanical Properties, Macroscopic Deformation Behavior, and Microstructure of Functionally Graded 22MnB5 Steel
(2021-03-24)
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 ...
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Comparison of Spaceborne and UAV-Borne Remote Sensing Spectral Data for Estimating Monsoon Crop Vegetation Parameters
(2021-04-20)
Various remote sensing data have been successfully applied to monitor crop vegetation parameters for different crop types. Those successful applications mostly focused on one sensor system or a single crop type. This study compares how two different sensor data (spaceborne multispectral vs unmanned aerial vehicle borne hyperspectral) can estimate crop vegetation parameters from three monsoon crops in tropical regions: finger millet, maize, and lablab. The study was conducted in two experimental field layouts (irrigated ...
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Potentials and Limitations of WorldView-3 Data for the Detection of Invasive Lupinus polyphyllus Lindl. in Semi-Natural Grasslands
(2021-10-28)
Semi-natural grasslands contribute highly to biodiversity and other ecosystem services, but they are at risk by the spread of invasive plant species, which alter their habitat structure. Large area grassland monitoring can be a powerful tool to manage invaded ecosystems. Therefore, WorldView-3 multispectral sensor data was utilized to train multiple machine learning algorithms in an automatic machine learning workflow called ‘H2O AutoML’ to detect L. polyphyllus in a nature protection grassland ecosystem. Different ...
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Sugar Beet Damage Detection during Harvesting Using Different Convolutional Neural Network Models
(2021-11-09)
Mechanical damages of sugar beet during harvesting affects the quality of the final products and sugar yield. The mechanical damage of sugar beet is assessed randomly by operators of harvesters and can depend on the subjective opinion and experience of the operator due to the complexity of the harvester machines. Thus, the main aim of this study was to determine whether a digital two-dimensional imaging system coupled with convolutional neural network (CNN) techniques could be utilized to detect visible mechanical ...
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Mirau-Based CSI with Oscillating Reference Mirror for Vibration Compensation in In-Process Applications
(2021-10-15)
We present a Mirau-type coherence scanning interferometer (CSI) with an oscillating reference mirror and an integrated interferometric distance sensor (IDS) sharing the optical path with the CSI. The IDS works simultaneously with the CSI and measures the distance changes during the depth scanning process with high temporal resolution. The additional information acquired by the IDS is used to correct the CSI data disturbed by unwanted distance changes due to environmental vibrations subsequent to the measurement. Due ...
Aufsatz
Augmented-Reality-basierte Assistenz für das Anlernen manueller und roboterunterstützter Montageprozesse
(2021-10-14)
Durch eine zunehmend flexibilisierte Produktion und relativ hohe Personalfluktuation bei einfachen Tätigkeiten wird das Anlernen neuer Mitarbeitender bzw. für neue oder geänderte Produktionsprozesse zunehmend relevanter. Konventionelle Anlernmethoden, bspw. durch Demonstration oder Arbeitspläne, haben Schwächen (bspw. binden sie zusätzliche Arbeitskraft oder sind kognitiv anspruchsvoll), die durch ein Augmented-Reality-(AR-)basiertes Assistenzsystem kompensiert werden können. Ein AR-Assistenzsystem zum Anlernen eines ...
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Iterative feature detection of a coded checkerboard target for the geometric calibration of infrared cameras
(2021-08-11)
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 ...
Aufsatz
Efficiency and agility of a liquid CO2 cooling system for molten metal systems
(2021-09-24)
In this study investigations on the efficiency and agility of a liquid CO2 cooling system, using expansion bores fed with liquid CO2 by capillary tubes, to form a thermal seal in a magnesium hot runner channel are performed in a test rig. Via temperature measurements the performance of different sets of cooling parameters is tested and cooling rates are identified depended on a varying nozzle geometry. To validate the measurements, the tests are modelled in a thermal simulation study. The applicability of the liquid ...