Fatigue Simulation of RC and R/FRC Wind Turbine Foundations for Lifespan Extension

As wind farms age, owners encounter pivotal decisions about either extending the operational lifespan of their facilities or pursuing complete decommissioning and repowering. Apart from the commercial factors guiding these choices, technical considerations must be assessed to gauge the risks associated with the continued operation of an aging fleet. In the context of onshore wind turbines, reinforced concrete shallow foundations stand as crucial components. Typically designed for a 20-year lifespan, there exists a pressing need to extend the life of foundations installed over 15 years ago. Both foundations and other structural turbine components endure cyclic fatigue loads. The utilization of fibre-reinforced concrete (FRC) presents enhanced competitiveness by reducing the need for traditional reinforcement, expediting construction, and delivering sustainability benefits. Furthermore, incorporating fibres can enhance fatigue behaviour, thereby positively impacting the service life of the foundation. This paper presents a preliminary numerical investigation into the influence of added fibres on the fatigue behaviour of wind tower foundations. The fatigue performance of the FRC foundation is compared with the standard behaviour of a conventional reinforced concrete foundation

Shear Strengthening of RC Beams with U-Wrapped FRCM Composites: State of the Art and Assessment of Available Analytical Models

Shear strengthening of existing reinforced concrete (RC) members with externally bonded (EB) fabric-reinforced cementitious matrix (FRCM) composites represents an attractive solution with respect to alternative strengthening techniques. The EB FRCM could be side-bonded, U-wrapped, or fully wrapped around the beam cross section. Compared with analogous research on EB fiber-reinforced polymers (FRPs), limited work was performed to study the contribution of the EB FRCM to the shear strength of RC beams and was mainly focused on the U-wrapped configuration. Although various analytical models to estimate the EB FRCM shear strength contribution were proposed, their accuracy and the role of different parameters on the results obtained were not thoroughly investigated. In this paper, a state of the art on side-bonded and U-wrapped FRCM shear-strengthened RC beams is provided and discussed to highlight the knowledge gaps and identify the main parameters that control the member shear strength. The accuracy of the available analytical models for the U-wrapped configuration is assessed with respect to a database of experimental FRCM shear-strengthened RC beams collated from the literature. The results obtained point out the key features that the analytical model should have to provide accurate and reliable predictions

Combined Long-Term Collision Avoidance and Stochastic Station-Keeping in Geostationary Earth Orbit

To limit the spread of space debris, space situational awareness (SSA) delineates guidelines to preserve current space assets. Developing effective collision avoidance maneuver (CAM) strategies is emerging as a global top priority among the considered countermeasures to debris-generating events. Despite most encounters happening over very short time frames, some conjunctions occur over a longer time window, such as in geostationary Earth orbit (GEO), where the involved objects may have small relative velocities. Besides, external perturbations, particularly the geopotential, lunisolar, and solar radiation pressure ones, exert forces on the spacecraft, causing it to deviate from its designated slot and potentially endanger neighboring satellites. This issue is compounded when considering state uncertainty. The presented work, therefore, introduces convex optimization approaches for long-term CAM and tailored stochastic station-leeping (SK) policy regarding longitude and latitude in this regime. The formulation enables continuous CAM and chance-constrained SK, ensuring satellite adherence to an assigned GEO slot with a given probability. Two kinds of chance constraints are devised: the first one does not consider the correlation between longitude and latitude, but the latter does

Brittle crack propagation simulation based on the Virtual Element Method and J_k-integral fracture criterion

Crack propagation simulation is a challenging topic in computational fracture mechanics, and the main issue is modeling the displacement discontinuity in the existing finite element mesh. The Virtual Element Method (VEM), as an extension of the Finite Element Method (FEM), permits the usage of arbitrarily shaped elements, including non-convex polygons or elements with hanging vertices, and has no distortion sensitivity. These features greatly facilitate VEM in addressing the crack propagation problem. An arbitrary crack propagation path can be achieved during the crack propagation process because the local mesh can be modified by adding or deleting vertices and/or edges, and by splitting one element into two polygons. This study simulates brittle crack propagation by the VEM with an element split strategy. The Jk-integral fracture criterion has been employed to determine the crack initiation and predict the crack propagation direction for mixed-mode loading conditions. The Jk-integral is computed directly by the path integral rather than by the domain integral, and its conservation has been verified. Some numerical applications have been implemented, including a mode-I crack problem test, a shear test of a single-edge notched plate and two different three-point bending tests. The numerical results show good agreement with the experiments, which verify the validity of the proposed simulation method for crack propagation

Leveraging Profiling to Bridge Healthcare Silos for Federated Analyses

Healthcare is more and more relying on digital information, bringing new challenges for its management, exploration, and usage. Healthcare data represents a challenge for information systems because, for privacy regulations, it cannot exit the original silo in which it has been produced (typically owned by hospitals), and may be of various kinds (clinical reports, DNA sequences, MRI scans, etc.). To manage this complexity, it is natural to use Federated Learning to safely analyze the underlying silos’ content. However, designing and running federated algorithms requires to know what the silos contain and how they can be joined (on which common attributes). Existing catalogs provide prelim-inary visualizations, which are hardly generalizable due to their under-lying use-case-tailored data models. To overcome these limitations, we provide a general catalog conceptual model as well as profiling techniques to extract information of interest from silos. Our proposed catalog is gen-eral enough to be used in various healthcare scenarios with diverse kinds of data. It also facilitates experts’ work in creating Federated Learning algorithms running in networks of interoperable healthcare silos

Navigating Twin Transition: Fostering Equitable and Anti-fragile Metropolitan Landscapes Enriching Digital Communities

The upcoming decades will be marked by the transformative dual green and digital transition fundamentally reshaping societies. Ensuring these transitions are equitable requires acknowledging disparities and anticipating socio-economic implications. This chapter underscores the importance of implementing strategies that embrace anti-fragility and de-risking (Taleb in Antifragile: things that gain from disorder. Global Penguin Random House, 2014). It advocates for a shift towards relational, pluriversal (Kothari et al. in Pluriverso. Dizionario del post-sviluppo. Orthotes, Napoli, 2021) modes of inhabiting urban spaces, preparing the context contents for employing digital tools to safeguard natural heritage, preserve local identity, and enhance community well-being (JRC in Understanding and acting on future risks and opportunities, Portfolio 26, 2023). This chapter explores the necessity of alternative dwelling modes that integrate communal existence, regenerative knowledge, and digital tools into metropolitan landscapes by challenging traditional design principles and promoting interconnectedness: a new emerging, nurturing diverse, and resilient ways of living. Our research underscores also the importance of metropolitan cultural heritage (Heritopolis Initiative) as a foundation for digital communities sustainable habitats. We translate these resources into actionable data and methodologies that drive policies that uphold heritage while advancing Twin Transition. A decentralised yet coordinated metropolitan framework is a system in which decision-making and authority are distributed across various entities or levels within a metropolitan area. However, a mechanism is still in place to ensure cooperation and alignment of goals among these entities. It implies a balance between local autonomy and collective coordination to efficiently manage urban development and services in a large city or metropolitan region

Verification-Oriented Specification of Multi-agent Interaction Patterns

Smart cyber agents are pivotal in software-intensive systems such as smart manufacturing, robotics, and the Internet of Things. These agents monitor physical surroundings through sensors and make impactful decisions that influence the environment. Software engineering challenges in this domain include the specification of interactive multi-agent tasks. The general-purpose Domain-Specific Language named LIrAs, Language for Interactive Agents, is a high-level language that allows for unambiguous custom pattern definition. Additionally, LIrAs facilitates interactions with human agents, a safety-critical situation requiring particular attention. This paper lays the foundation for LIrAs specifications translation to Stochastic Hybrid Automaton (SHA). The target SHA model structure follows a three-layer hierarchical structure and makes LIrAs specifications amenable to formal verification, specifically Statistical Model Checking, through the Uppaal tool, capable of including time-dependent ph..