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Aufsatz
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 ...
Aufsatz
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
3D printed dielectric lens for the gain enhancement of a broadband antenna
(2020-01-13)
A novel 3D printed dielectric lens to enhance antenna gain parameters is presented. The lens is fabricated using a fused deposition method (FDM) which is a cost‐effective and an efficient 3D printing technique. Poly‐methyl methacrylate (PMMA) is used as a dielectric material due to its good RF properties. The thickness of the dielectric lens is 14 mm and provides a gain enhancement of up to 6.9 dBi over a wide frequency range. The dielectric lens is designed and computationally analyzed to demonstrate refractive index ...
Aufsatz
Calculation of optical gain in AlGaN quantum wells for ultraviolet emission
(2020-09-03)
Stimulated emission from AlGaN based quantum wells (QWs) emitting at ultraviolet wavelengths is investigated theoretically. Maxwell–Bloch equations in the second Born approximation are solved self-consistently with the Poisson equation. The valence band dispersion is obtained from a 6-band kp-model. For a QW emitting at around 270 nm with a thickness of 2.2 nm, an estimated FWHM of 10 meV for homogeneous broadening and an excitonic red shift of 100 meV are extracted under typical laser conditions. From a comparison ...
Aufsatz
Efficient Solution of Distributed MIP in Control of Networked Systems
(2021-01-25)
Certain classes of optimization‐based control problems stated for networked systems involving hybrid dynamics and logical constraints can be cast into Mixed‐Integer Programming (MIP) problems. Since these belong to the complexity class NP‐hard, the motivation arises to find approximations of the optimal solution by distributed solution efficiently. For the cases that the cost functional is linear or quadratic and the constraints are linear, this paper proposes an alternative to the standard centralized schemes, by ...
Aufsatz
Environmental and Economic Performance of CO₂-Based Methanol Production Using Long-Distance Transport for H₂ in Combination with CO₂ Point Sources: A Case Study for Germany
(2022-03-29)
The use of CO₂-based hydrocarbons plays a crucial role in reducing the climate footprint for several industry sectors, such as the chemical industry. Recent studies showed that regions which are favorable for the production of CO₂-based hydrocarbons from an energy perspective often do not provide concentrated point sources for CO₂, which leads to an increased environmental impact due to the higher energy demand of direct air capture processes. Thus, producing H2 in regions with high renewable power potential and ...
Aufsatz
Numerical simulation of flow processes of wood‐polymer in extrusion dies
(2021-01-25)
The addition of wood to polymers results in wood‐polymer composites (WPC), whereby the wood content can be up to 80 %. This composite is mainly processed in extruded deckings. The extrusion die is an essential part of the process, which determines both process parameters and the final product. A characteristic of WPC extrusion dies is a partial solidification of the melt before leaving the die. This solidification is necessary to ensure a dimensionally stable extrusion. For the design of WPC extrusion dies numerical ...
Aufsatz
Modeling of fiber-coupled confocal and interferometric confocal distance sensors
(2022-04-06)
Laser distance sensors are a widespread, fast and contactless approach for distance and surface topography measurements. Main characteristics of those sensors are given by resolution, measurement speed and sensor geometry. With decreasing sensor size, the alignment of the optical components in sensor setup becomes more challenging. The depth response of optical profilers is analyzed to obtain characteristic parameters and, thus, to value the alignment and the transfer behavior of those sensors. We present a novel ...
Aufsatz
Development and Experiments on a Batch-Type Solar Roaster—An Innovative Decentralized System for Coffee Roasting
(2022-02-15)
About 70% of the harvested coffee is exported to the industrialized nations for value addition due to lack of processing and logistic facilities in developing coffee producer countries, thus leaving behind a marginal economic return for the growers. This research was conducted to investigate the roasting capacity of an innovatively developed batch-type directly solar radiated roasting system for the decentralized processing of coffee using solar energy. Central composite rotatable design (CCRD) was employed to design ...
Aufsatz
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 ...