Ein Wachstum der Luftfahrtindustrie wäre ohne den Fortschritt im Leichtbau nicht denkbar. Damit gehen moderne zerstörungsfreie Prüfverfahren einher, welche die Betriebssicherheit von Flugzeugen gewährleisten. Die Entwicklung neuer Leichtbaukonstruktionen führt erfordert zunehmend komplexere Bauteile, wodurch die Anforderungen an die zerstörungsfreien Prüfverfahren steigen. Die optische Messtechnik bietet hierbei den entscheidenden Vorteil der berührungslosen, schnellen und flächendeckenden Fehlstellendetektion. Zudem arbeiten sie materialunabhängig, was sie für die Prüfung moderner Werkstoffkomposite prädestiniert. Dennoch existieren Fehlerarten, die nur schwer auffindbar sind. Risse sind beispielsweise erst ab einem bestimmten Ausmaß mittels ZfP auffindbar. Sie wachsen exponentiell, was das Risiko eines Bruchs gefährlich macht. Sofern nicht bereits ein Aufklaffen vorliegt, sind Risse unter visueller, thermografischer und computertomografischer Betrachtung unsichtbar. Daher werden oftmals aufwändige Prüfungen wie das Farbeindringverfahren durchgeführt. Hingegen misst die Shearografie das Dehnungsverhalten einer Oberfläche unter einer Belastung. Dabei ist insbesondere die Ausrichtung des Shears zur Ausbreitungsrichtung einer Fehlstelle dafür verantwortlich, ob diese entdeckt wird. Da die Ausbreitungsrichtung in der Praxis unbekannt ist, wird in diesem Paper ein Dual-shear Versuchsaufbau mit transienter Objektbelastung diskutiert. Mittels FEM-Simulation und Digital Image Correlation wird gezeigt, dass sich Risse bevorzugt durch Anomalien im in-plane Dehnungsverhalten bemerkbar machen. In der praktischen Anwendung liefern die einfacher messbaren out-of-plane Anteile ebenfalls vielversprechende Ergebnisse. Der Sachverhalt wird für rissbehaftete Zugproben sowie anhand eines praktischen Beispiels im Vergleich zur aktiven Thermografie erörtert und die Einsatztauglichkeit der Dual-shear Methode aufgezeigt.

Reliable inspection of micro-scale components is essential in fields such as electronics and medical device manufacturing. To address this, a method combining digital speckle holography with microscopy has been developed. The resulting “Microferoscope” enables precise detection of structural defects in areas of just a few square millimetres. The method identifies minute deformations induced by controlled external stimuli, such as thermal or mechanical loading. Characteristic deformation patterns reveal structural anomalies. A dedicated module with orthogonal illumination allows for high-resolution measurement of deformations perpendicular to the component surface. Additionally, a three-dimensional module using laser diodes of different wavelengths enables the detection of both in-plane and out-of-plane deformations. Although high sensitivity in out-of-plane detection enhances defect recognition, it also increases susceptibility to environmental disturbances. This study compares both modules on micro-components to evaluate their sensitivity, robustness, and practical applicability.

This publication focuses on the production of low-cost prototypes of coaxial-waveguide transitions (CWTs) that achieve the performance level of industrial WR90 and WR187 CWTs. The assembly consists of a specially designed coupling element in stripline technology that merges into an SMA connector. It is embedded into a 3D printed housing treated with a metallic surface finishing to achieve compatibility with hollow waveguides. In the first part of this study, a copper spray varnish is used to create a conductive surface on the device under test (DUT). After assembly of the prototypes, network parameters will be extracted for one pair of transitions by carrying out a set of 2-port measurements. The individual performance of a singular DUT is then deembedded by using reference measurements of commercial-grade waveguides. This analysis shows that also S-parameter extraction on connectors with a poor transition is valid. Subsequently, the procedure for the developed WR90 CWT is applied to a WR187 waveguide standard, again followed by a performance analysis. The procedure briefly addresses the modified parameters and illustrates the results as S-parameters. A comparative analysis of the measurement results for each deembedded WR90 and WR187 prototype respectively, indicates a better performance for larger waveguide standards. In consistency with this observation, larger relative tolerances in manufacturing and difficulties in controlling a uniform metallization process are identified as the limiting factors of miniaturization. In the second part of this work, an alternative concept utilizing aluminum coating and a segmented manufacturing approach is developed, targeting reduced insertion loss but keeping the mechanical tolerance level. The redesign is based on the geometry of the prior WR90 prototype, but forming a plug-in kit with each body segment being clad in multiple thin layers of aluminum foil. The measurement results of these samples reveal the effects of increased conductivity and reduced irregularities in terms of significantly improved reflection and transmission parameters. The DUTs investigated in the third part of this work again originate from the initially manufactured variants. To investigate the effects of different metallic coatings, the copper varnish is now replaced by a silver based ink, which provides high conductivity and is therefore commonly used in additive manufacturing. The network measurements are repeatedly carried out with a varying number of layers of lacquer applications on the body's surface. By deembedding a singular part from the measurements, it is shown that increasing surface conductivity leads to a significant impact on transmission parameters. In direct comparison, the silver coated CWT outperforms both preceding variants with copper varnish or aluminum clad. With more than 95 % transmitted power, it is indeed competitive compared to the industrially manufactured WR90 CWT reference. To conclude, the study focuses on a comparison of three different additive manufacturing processes for equal hollow waveguide geometries at moderate frequencies. It proves that CWT parts are producible in a simple and rapid process. The production stages with the strongest impact on performance are identified and demonstrated to be controllable. The variant presented finally is able to achieve competitive performance compared to commercial-grade parts, especially when considering the enormous cost reduction. In addition, it is proven that the RF parameter extraction method for symmetric two-port networks presented earlier by the authors is also applicable when the DUT exhibits high insertion losses. The central aim of this work is to demonstrate that additive manufacturing combined with low-cost metallization techniques can produce coaxial-waveguide transitions that approach the performance of industrial WR90 standards. This novelty highlights the feasibility of achieving near-commercial-grade quality at a fraction of the cost, thereby extending the accessibility of high-frequency components to research and prototyping applications.

Cellular adhesion and contractility are essential for cell movement. In this study, we investigated the effects of actin stabilization on adhesion properties, contractility, and cell migration. For this, we used the recently synthesized actin stabilizer miuraenamide A (MiuA), which has been discussed as a more reliable alternative to the otherwise commonly used actin stabilizer jasplakinolide. We investigated the number and size of focal adhesions in RPE-1 cells and used single-cell force spectroscopy to evaluate the adhesion properties of those cells after MiuA treatment. We showed that MiuA increases the number of focal adhesions while decreasing their size and reduces adhesion energy and force. Additionally, we investigated its effects on the contractility of RPE-1 cells by measuring their contractile energy using pattern-based contractility screening (PaCS). We found no significant change in contractility after MiuA treatment. Finally, we confined RPE-1 cells in PDMS microchannels and analyzed their migration after treatment with MiuA, showing that neither their speed nor their persistence is affected by MiuA. To check that these effects are not specific to RPE-1 cells, we also analyzed the effects of MiuA treatment in MEF cells and neutrophils. Both MEF cells and neutrophils showed the same results as the RPE-1 cells. Our measurements indicate that, although altering focal adhesions significantly reduces adhesion, it does not impact cell contractility. This finding also clarifies why amoeboid migration, which operates independently of adhesion, remains unaffected. Additionally, it explains the previously observed reduction in mesenchymal migration, which relies on adhesion-based mechanisms.

High-renewables grids are planned in min but judged in milliseconds; credible studies must therefore resolve both horizons within a single model. Current adequacy tools bypass fast frequency dynamics, while detailed simulators lack multi-hour optimization, leaving investors without a unified basis for sizing storage, shifting demand, or upgrading transfers. We present a two-layer Hierarchical Model Predictive Control framework that links 15-min scheduling with 1-s corrective action and apply it to Germany’s four TSO zones under a stringent zero-exchange stress test derived from the NEP 2045 baseline. Batteries, vehicle-to-grid, pumped hydro and power-to-gas technologies are captured through aggregators; a decentralized optimizer pre-positions them, while a fast layer refines setpoints as forecasts drift; all are subject to inter-zonal transfer limits. Year-long simulations hold frequency within ±2 mHz for 99.9% of hours and below ±10 mHz during the worst multi-day renewable lull. Batteries absorb sub-second transients, electrolyzers smooth surpluses, and hydrogen turbines bridge week-long deficits — none of which violate transfer constraints. Because the algebraic core is modular, analysts can insert new asset classes or policy rules with minimal code change, enabling policy-relevant scenario studies from storage mandates to capacity-upgrade plans. The work elevates predictive control from plant-scale demonstrations to system-level planning practice. It unifies adequacy sizing and dynamic-performance evaluation in a single optimization loop, delivering an open, scalable blueprint for high-renewables assessments. The framework is readily portable to other interconnected grids, supporting analyses of storage obligations, hydrogen roll-outs and islanding strategies.