Maintainability and evolvability of control software in machine and plant manufacturing -- An industrial survey

Automated Production Systems (aPS) have lifetimes of up to 30-50 years, throughout which the desired products change ever more frequently. This requires flexible, reusable control software that can be easily maintained and evolved. To evaluate selected criteria that are especially relevant for maturity in software maintainability and evolvability of aPS, the approach SWMAT4aPS+ builds on a questionnaire with 52 questions. The three main research questions cover updates of software modules and success factors for both cross-disciplinary development as well as reusable models. This paper presents the evaluation results of 68 companies from machine and plant manufacturing (MPM). Companies providing automation devices and/or engineering tools will be able to identify challenges their customers in MPM face. Validity is ensured through feedback of the participating companies and an analysis of the statistical unambiguousness of the results. From a software or systems engineering point of view, almost all criteria are fulfilled below expectations

Exploring Large Language Models as a Source of Common-Sense Knowledge for Robots

Service robots need common-sense knowledge to help humans in everyday situations as it enables them to understand the context of their actions. However, approaches that use ontologies face a challenge because common-sense knowledge is often implicit, i.e., it is obvious to humans but not explicitly stated. This paper investigates if Large Language Models (LLMs) can fill this gap. Our experiments reveal limited effectiveness in the selective extraction of contextual action knowledge, suggesting that LLMs may not be sufficient on their own. However, the large-scale extraction of general, actionable knowledge shows potential, indicating that LLMs can be a suitable tool for efficiently creating ontologies for robots. This paper shows that the technique used for knowledge extraction can be applied to populate a minimalist ontology, showcasing the potential of LLMs in synergy with formal knowledge representation.Comment: Accepted at ISWC 2023 Posters and Demos: 22nd International Semantic Web Conference, November 6-10, 2023, Athens, Greec

Aerodynamic and aeroacoustic properties of axial fan blades with slitted leading edges

A detailed experimental analysis of the aerodynamic and aeroacoustic properties of flat-plate axial fans with slitted leading edges is performed. The sound emissions of five slitted leading edge designs are measured at a constant rotational speed and at a constant total-to-static pressure rise of the fans. For both cases, the fan blades with slitted leading edges reduce the turbulence interaction noise and lead to a reduction of the overall sound pressure level for volume flow rates above 0.6 m3 s−1 compared to an axial fan with solid leading edges. The far-field noise analysis shows that the slits result in a noise reduction for frequencies below 2 kHz and a noise increase above 2 kHz. In addition, sound source localization is conducted with a microphone array and rotating beamforming methods are applied. The identified sound source distributions prove that slitted leading edges reduce turbulence interaction noise, but generate broadband noise in the fan blades’ trailing edge regions. The maximum sound reduction due to the slits could be detected at a dimensionless frequency of $fh/\bar{w}\approx 0.5$, where f is the frequency, h is the height of the slit and $\bar{w}$ is the mean relative inflow velocity. The noise reduction mechanism on axial fan blades corresponds well to previous investigations on flat-plate airfoils with slits

On the Application and Limitations of Sound-Absorbing Materials for Axial Fan Blades

The design process of axial fans is based on increasing the aerodynamic efficiency and reducing the sound emissions. Low noise emissions are regarded as a quality feature and further are needed to fulfill increasing legal regulations. In order to achieve the lowest possible noise emission of the fan, a large number of blade modifications have already been investigated. For example, attempts have been made to reduce the turbulent ingestion noise of the fan with serrated, wavy or slotted leading edges. However, these modifications often reduce the aerodynamic efficiency. Therefore, the challenge is to find modifications of the fan blades, which induce low noise radiation at high efficiency. Since it was found that changes in the shape of the blade usually result in a reduced efficiency, the focus is on preserving the blade in its basic form. The reduction of the sound emission will be achieved by changing the materials in the region of the leading edge of the axial fan. Based on previous works on stationary airfoils, this study investigates the impact of porous materials in terms of noise reduction of axial fans. Porous materials with different acoustic impedance and airflow resistivity were selected in order to understand the physical noise reduction mechanisms. The material properties are determined experimentally using a two-port test rig. The axial fans are tested in a standardized axial fan test rig with regard to their acoustic and aerodynamic behavior. Two inflow conditions with different turbulence intensity are considered. In this study two different approaches are taken to identify the noise reduction mechanisms. First, the integration of sound-absorbing materials to increase the acoustic absorption. Second, the integration of a structured porosity, which should influence the momentum exchange in the flow. The first study shows that acoustic absorption is not the main cause of the noise reduction. On the one hand, this is due to the small surface area of the sound absorbers and, on the other hand, to the fact that the insertion of the absorbers generate a disturbed flow over the fan blade. To generate a quiet basic flow, a structured porosity was integrated in the second study. Here, a higher noise reduction could be observed for the axial fans. Further, it could be shown that a connection between the suction and the pressure side of the axial fan is indispensable for sound reduction and that structured porosities create higher noise reduction compared to sound-absorbing materials

Investigation of the Dzyaloshinskii-Moriya interaction and room temperature skyrmions in W/CoFeB/MgO thin films and microwires

Recent studies have shown that material structures, which lack structural inversion symmetry and have high spin-orbit coupling can exhibit chiral magnetic textures and skyrmions which could be a key component for next generation storage devices. The Dzyaloshinskii-Moriya Interaction (DMI) that stabilizes skyrmions is an anti-symmetric exchange interaction favoring non-collinear orientation of neighboring spins. It has been shown that materials systems with high DMI can lead to very efficient domain wall and skyrmion motion by spin-orbit torques. To engineer such devices, it is important to quantify the DMI for a given material system. Here, we extract the DMI at the Heavy Metal/Ferromagnet interface using two complementary measurement schemes, namely, asymmetric domain wall motion and the magnetic stripe annihilation. By using the two different measurement schemes, we find for W(5nm)/Co20Fe60B20(0.6 nm)/MgO(2 nm) the DMI to be 0.68 +/- 0.05 mJ/m(2) and 0.73 +/- 0.5 mJ/m(2), respectively. Furthermore, we show that this DMI stabilizes skyrmions at room temperature and that there is a strong dependence of the DMI on the relative composition of the CoFeB alloy. Finally, we optimize the layers and the interfaces using different growth conditions and demonstrate that a higher deposition rate leads to a more uniform film with reduced pinning and skyrmions that can be manipulated by spin orbit torques. Published by AIP Publishing