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Sustainable tribological solutions: laser-textured Cr3C2/Cr2O3-coated shaft sleeves
No full textSliding bearings in pumps operating under corrosive and insufficiently lubricated conditions are subjected to high levels of wear and degradation, frequently resulting in accelerated component failure. These bearings typically utilize tungsten carbide with a cobalt binder (WC-Co) due to its superior resistance to wear and corrosion. However, growing concerns regarding the sustainability and limited availability of tungsten and cobalt have intensified the efforts to develop alternative, resource-efficient solutions. To address this challenge, a novel ceramic coating composed of chromium carbide-chromium oxide (Cr3C2/Cr2O3), deposited using high-velocity suspension flame spraying (HVSFS), was evaluated as an environmentally sustainable replacement for WC-Co coatings in sliding bearing applications. Shaft sleeves were coated and subsequently cylindrical grinding was applied to achieve tight dimensional tolerances and optimal surface finish. Ultrashort-pulsed laser surface texturing was then employed to create engineered dimples designed to improve friction behavior under challenging lubrication conditions. A fine cylindrical grinding was subsequently applied to remove residual pile-up and flatten inter-dimple areas. Grinding performance evaluation demonstrated 20 % reduction in tangential grinding force and 37 % improvement in surface roughness (Rz) compared to WC-Co, confirming the coating's suitability for precision finishing. Tribological tests under water-lubricated sliding conditions revealed that laser-textured Cr3C2/Cr2O3 coatings exhibited up to 50 % lower wear mass than non-textured coatings and achieved friction coefficients between 0.02 and 0.04, matching WC-Co performance while showing greater stability and lower variability. In speed-ramped Stribeck testing, laser-textured surfaces maintained reduced friction variability and closely followed the frictional trend of WC-Co, particularly in the boundary-to-mixed lubrication regime. These findings highlight the combined advantages of the proposed coating system in terms of machinability, wear resistance, friction control, and operational consistency, offering a viable and sustainable alternative for high-performance sliding bearing applications in water-lubricated environments.58
A Systematic Review of Packages for Time Series Analysis †
No full textThis paper presents a systematic review of Python packages with a focus on time series analysis. The objective is to provide (1) an overview of the different time series analysis tasks and preprocessing methods implemented, and (2) an overview of the development characteristics of the packages (e.g., documentation, dependencies, and community size). This review is based on a search of literature databases as well as GitHub repositories. Following the filtering process, 40 packages were analyzed. We classified the packages according to the analysis tasks implemented, the methods related to data preparation, and the means for evaluating the results produced (methods and access to evaluation data). We also reviewed documentation aspects, the licenses, the size of the packages’ community, and the dependencies used. Among other things, our results show that forecasting is by far the most frequently implemented task, that half of the packages provide access to real datasets or allow generating synthetic data, and that many packages depend on a few libraries (the most used ones being numpy, scipy and pandas). We hope that this review can help practitioners and researchers navigate the space of Python packages dedicated to time series analysis. We also provide an updated list of the reviewed packages online.5
Elucidating the efficiency limit of silicon-based monolithic tandem cells through the combination of Auger and Shockley-Queisser limits
No full text10301039Accurate theoretical efficiency limits are critical for diagnosing loss mechanisms and guiding optimization in solar cell technologies. While the Shockley-Queisser (SQ) limit remains the most widely used framework for assessing tandem and multijunction devices, its assumptions - purely radiative recombination and ideal light absorption - do not account for the intrinsic limitations of silicon (Si), the dominant photovoltaic material. In particular, Si's indirect bandgap resulting in Auger recombination imposes a lower efficiency ceiling. In this work, we present a rigorous simulation approach that combines SQ-limited top cells with an Auger-limited Si bottom cell, accounting also for luminescent coupling (LC). This hybrid modeling approach yields a maximum theoretical efficiency of 43.2% for an ideal two-terminal Si-based tandem device, compared to 45.2% using the unrealistic assumption of a SQ-limited Si bottom cell. The optimal configuration features a top cell bandgap of 1.71 eV and a 300 μm-thick Si bottom cell, with a minor efficiency penalty of only 0.1% for a more typical thickness of 120 μm. Accounting for LC values typical for perovskite top cells reduces the optimum efficiency to 42.4%. Special emphasis is placed on the interpretation of fill factor (FF), highlighting the need for correct analytical FF limit (FF0) calculations using an appropriate ideality factor, which is 5/3 for silicon based tandem at the theoretical limit. To support future benchmarking, we provide lookup tables of current–voltage (JV) parameters for a range of top cell bandgaps, bottom cell properties, multijunction stacks with up to six subcells, and perovskite-specific top cell properties. These results offer reliable efficiency limits for the evaluation of high-efficiency silicon-based tandem and multijunction solar cells.1
Tyre-derived ecotoxicity: Differentiating the effects from particles and chemical leachates on the blue mussel Mytilus edulis
No full text934951Tyre particles contain complex chemical additives that can leach out into the aquatic environment, posing potential risks to marine organisms. Despite growing evidence of adverse effects, the relative importance of particle-driven versus chemically mediated toxicity remains poorly explored, especially under environmentally relevant exposure scenarios. This study used the blue mussel (Mytilus edulis) as a model to differentiate these effects by exposing individuals to cryomilled tyre particles (TP), their leachates (L) and pre-leached particles (TPL) over 36 days at the environmentally relevant concentration of 0.1 g/L. Chemical analysis confirmed uptake of key organic additives such as poly(1,2-dihydro-2,2,4-trimethylquinoline) (TMQ), N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD), and 6PPD-quinone (6PPDQ), with certain compounds persisting after depuration. Particle-exposed mussels accumulated higher additive concentrations than those exposed to only leachates, indicating enhanced chemical release from particles. Biomarker responses revealed signs of oxidative stress and neurotoxicity in exposed mussels across all treatments, with earlier responses in leachate exposure and delayed responses during particle exposures. These results demonstrate that chemical additives are key toxicity drivers alongside physical particles, highlighting the importance of considering both pathways in environmental risk assessments. To our knowledge, this study is among the first to experimentally separate particle and leachate specific effects in mussels by using tyre particles before and after leaching to create contrasting chemical loads, thereby providing novel insights into their distinct and combined impacts on marine biota.
Hydrogen-based functional recycling of Nd-Fe-B sintered magnets: influence on GBDP microstructure evolution and possibilities to improve the resulting properties
No full text◼ Hydrogen decrepitation (HD) of over 100 commercial GBDP magnets (0.5 kg) ◼ Composition: Nd 23.0 Pr 6.15 Tb 1.76 Dy 0.24 Fe bal B 0.93 Co 0.89 Ga 0.21 Al 0.13 Cu 0.08 (wt.%) ◼ Jet-milling to particle size D 50 of 5.4 μm, aligning, pressing, and sintering at 1100 °C for 4 h followed by annealing at 700 °C for 1 h and 500 °C for 1 h ◼ Investigations on the changes of the GBDP microstructure (core-shell) and magnetic properties ◼ GBDP with 1.5 wt.% pure Tb-foil at 900 °C for 9 h with subsequent lowtemperature annealing to restore the magnetic properties SEM-BSE images, EDS mappings, and EDS line scans through the functional recycling process. While at the GBD scrap magnet a narrow Tb-core-shell structure with 0.5 μm can be observed, the other samples show less clear coreshell formation but broader Tb enrichments at the outer regions of the grains. APT investigation of GBD scrap magnet (left) and recycled magnet (right) reveals beside a more homogenous distribution of Tb and disappearance of the coreshell microstructure also changes in the grain boundary elemental distribution through functional recycling
Evolutionary Self-adaptation of Complex Production Processes and Products. Evolutionäre Selbstanpassung komplexer Produktionsprozesse und Produkte
No full text7487511181
5G-NTN GEO-based Over-The-Air Demonstrator using OpenAirInterface
No full text1101145G services combined with the satellites, also termed 5G Non-Terrestrial Networks (5G-NTN), have the capability of providing connectivity to the areas which were previously either unreachable or too costly to be reached by terrestrial communication networks. Proof-of-Concept (POC) demonstrators, preferably based on open-source implementation are desirable to expedite the ongoing research on 5G-NTN. In this work, we discuss the contributions made during the project 5G-GOA: 5G-Enabled Ground Segment Technologies Over-The-Air Demonstrator which aims to provide direct access to 5G services to a UE through a transparent payload Geostationary (GEO) satellite. 5G-GOA uses the open-source Software-Defined-Radio (SDR) platform OpenAirInterface (OAI) and does the necessary adaptations to achieve its objectives. Adaptations span physical layer techniques (e.g., synchronization) up to upper layer implementations (e.g., timers and random-access procedures) of the Radio Access Network (RAN). The adaptations are based on 3GPP 5G-NTN discussions and the solutions are compliant with the recently frozen 3GPP Release-17. An end-to-end SDR-based 5G-NTN demonstrator has been developed for Over-The-Satellite (OTS) testing. We present results from several experiments that were conducted for in-lab validation of the demonstrator using a satellite channel emulator before going live with OTS tests. Experimental results indicate the readiness of the demonstrator for OTS testing which is scheduled during ICSSC 2022. The source code has been submitted to OAI public repository and is available for testing
Microoptics for flat display backlighting Mikrooptiken für flache Bildschirmhinterleuchtung
No full text138139Displays are the basis elemnt for data visualisation in many applications. Often classical mechanical driven instrument clusters are replaced by displays, especially in automotive dashboards. Ambient illumination is more and more included to reach a homogeneous industrial design appearance. To be able to realise those applications very flat backlighting systems are required with the potential to fit into 3D shaped base geometries. Direct backlighting adds the possibility to address specific regions of the display individually, leading to energy saving and improved efficiency and contrast. Optical concepts for backlighting units are directly linked to the target thickness of the setup. With adapted optical concepts and introduction of microoptical elements very low thicknesses <3mm are possible
Synergism between IL-33 and MRGPRX2/Fc&#x3B5;RI Is Primarily Due to the Complementation of Signaling Modules, and Only Modestly Supplemented by Prolonged Activation of Selected Kinases
No full textSkin mast cells (MCs) express high levels of MRGPRX2, Fc&#x3B5;RI, and ST2, and vigorously respond to their ligands when triggered individually. IL-33/ST2 also potently synergizes with other receptors, but the molecular underpinnings are poorly understood. Human skin-derived MCs were stimulated via different receptors individually or jointly in the presence/absence of selective inhibitors. TNF was quantified by ELISA. Signaling cascades were studied by immunoblot. TNF was stimulated by Fc&#x3B5;RI &#x2248; ST2 &#x003E; MRGPRX2. Surprisingly, neither Fc&#x3B5;RI nor MRGPRX2 stimulation elicited NF-&#x3BA;B activation (I&#x3BA;B degradation, p65 phosphorylation) in stark contrast to IL-33. Accordingly, TNF production did not depend on NF-&#x3BA;B in Fc&#x3B5;RI- or MRGPRX2-stimulated MCs, but did well so downstream of ST2. Conversely, ERK1/2 and PI3K were the crucial modules upon Fc&#x3B5;RI/MRGPRX2 stimulation, while p38 was key to the IL-33-elicited route. The different signaling prerequisites were mirrored by their activation patterns with potent pERK/pAKT after Fc&#x3B5;RI/MRGPRX2, but preferential induction of pp38/NF-&#x3BA;B downstream of ST2. Fc&#x3B5;RI/MRGPRX2 strongly synergized with IL-33, and some synergy was still observed upon inhibition of each module (ERK1/2, JNK, p38, PI3K, NF-&#x3BA;B). IL-33&#x2019;s contribution to synergism was owed to p38 &#x003E; JNK &#x003E; NF-&#x3BA;B, while the partner receptor contributed through ERK &#x003E; PI3K &#x2248; JNK. Concurrent IL-33 led to slightly prolonged pERK (downstream of MRGPRX2) or pAKT (activated by Fc&#x3B5;RI), while the IL-33-elicited modules (pp38/NF-&#x3BA;B) remained unaffected by co-stimulation of Fc&#x3B5;RI/MRGPRX2. Collectively, the strong synergistic activity of IL-33 primarily results from the complementation of highly distinct modules following co-activation of the partner receptor rather than by altered signal strength of the same modules.122
Digital twin for predictive maintenance in production - Physics-based modelling and simulation to optimize data-driven models Digitaler zwilling zur vorausschauenden instandhaltung in der produktion - Physikbasierte modellierung und simulation zur optimierung datengetriebener modelle
No full text139150The analysis of production systems and products during operation or usage is a key competitive factor for companies. Digital twins of products and production systems are gaining in importance here since, in addition to the analysis of operating data to estimate remaining useful life, they identify potential failure mechanisms, making it easier to locate the causes of failure. This paper outlines a concept of digital twins for predictive maintenance. The concept serves as a basis for an approach for the development of physics-based and data-driven models and their harmonization. In particular, the generation of data using a physics-based simulation model for the optimization of a data-driven model is highlighted. The concept was realized in a concrete use case for the prediction of filter clogging of a thermal regulator. The procedure is intended to support manufacturing companies in the implementation of predictive maintenance in order to optimize not only the lifetime of machines but also the next product generation