Delft University of Technology

• Research highlight 1: Inflow inhomogeneity, due to the grid proximity, causes dominant tonal noise in the frequency band affected by ingested turbulence. • Research highlight 2: Blade-thickness blockage amplifies the effect of inflow inhomogeneity on unsteady loading and acoustics. • Research highlight 3: Upstream turbulence does not affect the mean flow over the blade and the first blade-passing frequency amplitude. • Research highlight 4: Upstream turbulence effects fade after reattachment; trailing-edge noise is unaffected. This work investigates the effect of grid-generated turbulence ingestion on noise generation in a propeller operating at a low Reynolds number using high-fidelity, scale-resolved simulations. The numerical setup reproduces experiments carried out at Delft University of Technology, where inflow turbulence is generated by a grid placed within a duct. It is found that, upstream of the propeller, the longitudinal correlation length of the streamwise velocity component increases with respect to the case without the propeller. The opposite happens for the transversal one. The turbulent inflow impinging on the propeller blades does not alter the mean flow characteristics over the propeller blades, e.g., the mean static pressure coefficient. However, it increases the root mean square of the pressure fluctuations up to the turbulent reattachment point of the laminar separation bubble, while leaving the downstream region mostly unaffected. This causes a broadband increase in the radiated noise in the low-to-mid frequency range, as confirmed by applying Amiet’s noise-prediction model with input data sampled near the propeller blades’ leading edge. The far-field noise spectra are characterized not only by an increase in the broadband noise with respect to the clean inflow case, but also by tonal components at multiples of the blade-passing frequency. It is found that these tones are caused by the footprint of the turbulence grid that introduces flow inhomogeneities at the propeller location for this specific configuration. It is recommended, when performing experiments and simulations, to verify if any footprint of the turbulence grid is present, not only by performing single-point measurements but also by measuring the time-averaged flow field before installing the propeller.

To investigate how task delegation for perioperative anticoagulation management is reported in protocols and daily practice, and how this translates to additional information in work-as-imagined and work-as-done using FRAM to identify improvement possibilities. Existing FRAM visualisations of perioperative anticoagulant management in a Dutch academic hospital were extended to include task delegation in protocols using document analysis and in daily practice using a focus group of eight healthcare professionals, analysed using content analysis. Distinguishing between formal responsibility and task execution revealed additional functions and roles in both work-as-done and work-as-imagined, resulting in more discrepancies between work-as-done and work-as-imagined. Professionals experienced responsibility for delegated tasks, even without formal accountability, and needed to feel qualified and capable as well as complete clear information to accept these tasks. Including task delegation in FRAM models improves the understanding of healthcare processes, communication about distribution of responsibilities and thereby development of more effective improvement strategies.

• Dynamic workflows allow changing design variables, tools and constraints at runtime • Dynamic MDAO workflows enable system architecture optimization in a single loop • New methodology to formulate, visualize, exchange and materialize dynamic workflows • Switches, branches, and subworkflows enable dynamic behavior within workflows • Less runtime and fewer function evaluations for architecture design optimizations Many architectural design trade-offs must be performed during the conceptual design of complex systems, such as aircraft, to identify promising design concepts. A few architectures are usually selected and traded to keep the process manageable, but this can suffer from biases. Ideally, an optimizer, supported by a multidisciplinary system evaluator, should enable architecture design space exploration. However, incorporating architectural design choices into a multidisciplinary design optimization is challenging due to changing design variables, constraints, and disciplinary tools associated with different architectural designs. This paper proposes a new formal methodology for dynamic Multidisciplinary Design Analysis and Optimization (MDAO) workflows. These workflows allow the design variables, tools, and constraints to change during execution, enabling evaluation and optimization of different architectures within a single MDAO system definition. Switches, branches, and subworkflows are introduced to enable dynamic behavior within the workflow. Together, they allow for a complete mathematical problem definition and consistent formalization. Accordingly, extensions to the eXtended Design Structure Matrix (XDSM) and the Common MDO Workflow Schema (CMDOWS) are presented to enable the visualization, storage, and exchange of dynamic workflows. An automated MDAO formulation, integration, and execution process is extended to ease the setup of these workflows. The methodology has been verified and validated using a mathematical optimization problem from literature. The dynamic workflow successfully discovered a Pareto front comprising multiple architectural design options. Furthermore, the results demonstrate that a single dynamic workflow can identify optimal architectures more efficiently than multiple static workflows, requiring significantly less execution time and fewer function evaluations.

• We offer an evaluation of technical experts' and community members’ knowledge and perception on the use of nature-based solutions for coastal protection across multiple European countries. • For technical experts, a good level of knowledge correlated with a higher level of consciousness regarding nature-based solutions employment. • Compared to technical experts, community members showed a more limited knowledge on nature-based solutions but overall support for their implementation with desire for sustainable and eco-friendly management practices. • Results offer initial insights for coastal planners, guide larger-scale studies, inform community-scale research, and highlight opportunities to improve knowledge exchange. The use of nature-based solutions (NBSs) in coastal management strategies is gaining popularity, with broad consensus on the critical role of public engagement in assessing the benefits of sustainable practices. However, the number of existing studies that tackle public knowledge and perception of NBSs in coastal management is still low and most studies only target specific communities. As a result, it is challenging to determine whether these findings reflect general trends or are influenced by unique circumstances in the studied communities. To clarify this, it is essential to assess the broader public perspective on the use of NBSs in coastal management. Here we assess the results of a pilot study conducted across Europe to evaluate technical experts’ and community members’ knowledge and perception on the use of NBSs for coastal protection. The evaluation was conducted by collecting responses provided to a survey distributed via social media. The study focuses on three countries: United Kingdom, Netherlands and Italy. The survey revealed common trends across the three countries. There is general support for the application of these solutions in coastal management amongst both groups, which correlates positively with concern for flooding and erosion. While technical experts have a solid understanding of the topic, which corresponds to a considerable degree of awareness and a higher level of consciousness regarding NBSs implementation, the community members’ support is accompanied by an overall more limited knowledge of what NBSs entail (higher amongst residents of coastal areas) but also a considerable desire for more sustainable and eco-friendly management practices. While offering an initial insight into public perceptions of NBSs for coastal planners, these results can also guide larger-scale perception studies, provide a framework for interpreting community-scale research, and highlight opportunities to improve knowledge exchange between technical experts and community members.

Pea proteins can act not only as interfacial stabilizers of oil-in-water emulsions but also as gelling agents in the continuous phase. Protein gelation, rather than droplet jamming, may be the main mechanism of emulsion stability, providing a physical explanation for the creaminess of high-protein plant-based emulsions. Spin-echo small angle neutron scattering (SESANS) with D2O/H2O contrast variation was used to study 15% pea protein dispersions and emulsions with 40-60% rapeseed oil, 7.5% protein at pH3 to 6.5. SESANS investigates length scales up to tens of micrometres, enabling simultaneous analysis of protein networks and oil droplets without dilution. Complementary small angle X-ray/neutron scattering were used to validate protein aggregate size, and hydration. Protein dispersions at neutral pH formed mass fractal networks with small individual building blocks (radius∼38Å, hydration ∼70%). Emulsions consisted of oil droplets embedded in these networks, with droplet radii decreasing at higher oil fractions due to an effective higher protein concentration in the continuous phase, creating a denser network. Dispersions and emulsions at lower pH contained aggregated clusters of denatured proteins. These coarse and inhomogeneous networks gave increasing droplet radii at lower pH. Contrast variation enabled the separation of protein and oil droplet scattering, demonstrating that protein gelation rather than droplet jamming is the main mechanism of stability. This gives a physical explanation of the high viscosity of high-protein plant-based emulsions and is promising for these plant materials to be used as gelling agents in food applications.

Urban Air Mobility (UAM) systems offer a three-dimensional transportation alternative by using low-altitude airspace, with the potential to reduce travel times and improve access to mobility in regions underserved by current transportation systems. To support efficient design and operation of UAM systems, we develop an integrated optimization framework in response to three interrelated challenges: (i) land use, aeronautical feasibility, community acceptance and other factors that restrict the number of potential locations for vertiports, (ii) bidirectional demand–supply interaction that needs to be considered, as the level of service influences demand for UAM and operators adjust the level of service in response to demand, and (iii) strong interactions between strategic decisions on the distribution of ground infrastructure, tactical decisions on eVTOL fleet size and operational decisions on dispatching and repositioning. Analyzing the decisions in isolation can lead to poor estimates of the overall system performance. The framework consists of (1) a knock-off criteria analysis model for the identification of a realistic set of candidate locations for vertiports, (2) integer programming models in which strategic, tactical and operational decision levels are modeled, and (3) pre-processing techniques to generate near-optimal solutions for real-world instances. By applying the framework in a large-scale real-world setting in the Île-de-France region, we demonstrate complex interactions between strategic, tactical, and operational decision levels and customer demand, revealing various trade-offs between operator profit and traveler generalized travel costs. • Provide realistic candidate vertiports in the Île-de-France region using knock-off criteria screening. • Integrate vertiport location selection with eVTOL fleet sizing and operations and demand interaction. • Identify non-linear trade-offs between operator profit and user generalized travel costs. • Conclusions on the economic viability of UAM operations. • Identification of UAM network structures with distinct vertiport roles.

To explore barriers and facilitators in implementing the Safety Climate Thermometer (SCT), a new tool designed to support team-level safety culture improvement in surgical settings. The SCT acts through visual insights into safety culture themes, acting as a conversation starter, and interdisciplinary team meetings about this topic. It aims to facilitate daily practice changes. The SCT has previously been developed using user-centered design methods, which consisted of a scoping literature review and international survey. A qualitative implementation study using semi-structured interviews and observational data, guided by the implementation outcomes framework. Three surgical teams from Dutch hospitals of varying size participated between 2021 and 2023 and used the SCT's visual input and interdisciplinary team meeting structure for 7 months. Seventeen healthcare professionals, including nurses, surgeons, and managers, took part in the SCT process and subsequent interviews. The SCT facilitated an anonymous, online assessment followed by structured interprofessional discussions and goal-setting for safety improvement. Participants reported high usability and acceptability due to the tool's intuitive design and anonymity. The SCT was adaptable to different surgical contexts, though smaller teams with motivated champions and in-person facilitation appeared most suitable. Key barriers included high turnover and work pressure, competing priorities, lack of trust, and survey fatigue. Facilitators include in-person external facilitation and "protected time." Reported positive effects included strengthened team cohesion and a greater sense of being heard. The SCT is a practice-oriented, user-friendly tool for improving safety culture through team-based reflection and dialogue. Future use should prioritize exploration of contextual factors.