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Aufsatz
Miniaturized interferometric confocal distance sensor for surface profiling with data rates at ultrasonic frequencies
(2023-01-12)
Point-wise measuring profilometers like the tactile stylus instruments or optical sensors are established measurement tools in science and industry to measure and characterize surface textures. We present a fiber-coupled laser interferometric confocal distance sensor for surface profiling. The sensor is characterized by small geometric dimensions and by its high lateral
scanning speed. The ability to measure specularly reflecting and rough surface textures are demonstrated by performing several measurements on a ...
Aufsatz
Model-based investigations of ferroelectric energy harvesting with regard to an improvement of life span and operability
(2023-02-13)
A new ferroelectric energy harvesting concept is investigated theoretically, based on a thermo-electromechanical multiscale constitutive framework in connection with the so-called condensed method. Taking advantage of comparatively large changes of strain and polarization due to domain switching, the electric output is higher compared to what is commonly known as
piezoelectric energy harvesting. Dissipative self-heating and augmented damage accumulation, on the other hand, may impede the operability of the harvesting ...
Aufsatz
Influence of Fiber Volume in Hybrid Short Glass/Cellulose Reinforced Thermoplastic Compounds
(2022-09-22)
Glass fibers (GF) and regenerated cellulose fibers (RCF) are possible partners in the hybrid reinforcement of thermoplastics because of their different properties. Due to the weak bonding properties of polypropylene, coupling agents are used and the fiber volume content is set high to achieve high reinforcing effects. A lower fiber content of GF can raise the toughness properties of a reinforced polypropylene which is investigated in this study with different ratios of GF and RCF.
The composites are tested in tensile ...
Aufsatz
Experimental and numerical polarization analysis of the 3D transfer behavior in microsphere-assisted interferometry for 1D phase gratings
(2023-06-08)
Enhancing the lateral resolution in optical microscopy and interferometry is of great interest in recent research. In order to laterally resolve structures including feature dimensions below the Abbe resolution limit, microspheres in the optical near-field of the specimen are shown to locally improve the resolution of the imaging system. Experimental and simulated results following this approach are obtained by a high NA Linnik interferometer and analyzed in this contribution. They show the reconstructed surface of ...
Aufsatz
Time Series Optimization-Based Characteristic Curve Calculation for Local Reactive Power Control Using Pandapower-PowerModels Interface
(2023-05-29)
Local reactive power control in distribution grids with a high penetration of distributed energy resources (DERs) will be essential in future power system operation. Appropriate control characteristic curves for DERs support stable and efficient distribution grid operation. However, the current practice is to configure local controllers collectively with constant characteristic curves that may not be efficient for volatile grid conditions or the desired targets of grid operators. To address this issue, this paper ...
Aufsatz
Influence of Different Hot Runner-Systems in the Injection Molding Process on the Structural and Mechanical Properties of Regenerated Cellulose Fiber Reinforced Polypropylene
(2023-04-18)
The increasing demand for renewable raw materials and lightweight composites leads to an increasing request for natural fiber composites (NFC) in series production. In order to be able to use NFC competitively, they must also be processable with hot runner systems in injection molding series production. For this reason, the influences of two hot runner systems on the structural and mechanical properties of Polypropylene with 20 wt.% regenerated cellulose fibers (RCF) were investigated. Therefore, the material was ...
Aufsatz
Additive Timber Manufacturing: A Novel, Wood-Based Filament and Its Additive Robotic Fabrication Techniques for Large-Scale, Material-Efficient Construction
(2021-08-13)
Additive manufacturing (AM), as resource-efficient fabrication processes, could also be used in the dimensions of the construction industry, as a variety of experimental projects using concrete and steel demonstrate. In timber construction, currently few additive technologies have been developed having the potential to be used in large scale. Currently known AM processes use wood in pulverized form, losing its inherent structural and mechanical properties. This research proposes a new material that maintains a complete ...
Aufsatz
Development of a hybrid mixed-mode solar dryer for product drying
(2023-02-28)
Sun drying in the open air is quite popular worldwide. However, the use of solar dryers to preserve various perishable agricultural products is a relatively new area of study, and the long-term effects of this method are not yet fully understood. The slow drying process in direct sunlight can contaminate the dried materials by soil and insects. To overcome these challenges, we devised a sun drying system that included a heating part, a drying area, a portable stand, fans, and a 50-W photovoltaic panel. An alternate ...
Aufsatz
Metastable CrMnNi steels processed by laser powder bed fusion: experimental assessment of elementary mechanisms contributing to microstructure, properties and residual stress
(2022-12-18)
The complex thermal history imposed by the laser-based powder bed fusion of metals (PBF-LB/M) process is known to promote the evolution of unique microstructures. In the present study, metastable CrMnNi steels with different nickel contents and, thus, different phase stabilities are manufactured by PBF-LB/M. Results clearly reveal that an adequate choice of materials will allow to tailor mechanical properties as well as residual stress states in the as-built material to eventually redundantize any thermal post-treatment. ...
Aufsatz
Three‑dimensional close‑to‑substrate trajectories of magnetic microparticles in dynamically changing magnetic field landscapes
(2022-12-03)
The transport of magnetic particles (MPs) by dynamic magnetic field landscapes (MFLs) using magnetically patterned substrates is promising for the development of Lab‑on‑a‑chip (LOC) systems. The inherent close‑to‑substrate MP motion is sensitive to changing particle–substrate interactions. Thus, the detection of a modified particle–substrate separation distance caused by surface binding of an analyte is expected to be a promising probe in analytics and diagnostics. Here, we present an essential prerequisite for such ...