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Multiphysics modelling of the Activated Corrosion Products generation and transport in the WCLL PbLi loop with GETTHEM
Full text linkOne of the main milestones towards the development of the EU DEMO reactor is to demonstrate the feasibility of a closed tritium fuel cycle, a key aspect for the generation of electricity from fusion energy by the middle of the century. In view of this, the design of the breeding blanket (BB) has a key role. A candidate design for the EU DEMO BB is the Water-Cooled Lithium-Lead (WCLL) concept, where eutectic lithium-lead (PbLi) is circulated in a suitable closed circuit. A key issue in the design of the PbLi circuit is the evaluation of the inventories of Activated Corrosion Products (ACPs), which are solid particles corroded from structural materials and eventually activated in the blanket, transported inside the loop within the PbLi. In recent years, a PbLi loop model has been implemented in the GETTHEM code, a system-level tool for the thermal-hydraulic modelling of BB and related subsystems. In this work, in addition to the already existing assessment of corrosion phenomena, models of different pieces of physics necessary for a comprehensive assessment of the ACP inventories are added to the PbLi loop model in GETTHEM. Specifically, these include activation and decay of the corroded species in the BB. For the latter, a sink term for the radioactive decay and a source term for the transmutation due to neutrons interaction with materials are introduced in the mass conservation equations for each ACP. To demonstrate the code capabilities, a representative test case is presented
Hier-EgoPack: Hierarchical Egocentric Video Understanding with Diverse Task Perspectives
Full text linkOur comprehension of video streams depicting human activities is naturally multifaceted: in just a few moments, we can grasp what is happening, identify the relevance and interactions of objects in the scene, and forecast what will happen soon, everything all at once. To endow autonomous systems with such a holistic perception, learning how to correlate concepts, abstract knowledge across diverse tasks, and leverage tasks synergies when learning novel skills is essential. A significant step in this direction is EgoPack, a unified framework for understanding human activities across diverse tasks with minimal overhead. EgoPack promotes information sharing and collaboration among downstream tasks, essential for efficiently learning new skills. In this paper, we introduce Hier-EgoPack, which advances EgoPack by enabling reasoning also across diverse temporal granularities, which expands its applicability to a broader range of downstream tasks. To achieve this, we propose a novel hierarchical architecture for temporal reasoning equipped with a GNN layer specifically designed to tackle the challenges of multi-granularity reasoning effectively. We evaluate our approach on multiple Ego4D benchmarks involving both clip-level and frame-level reasoning, demonstrating how our hierarchical unified architecture effectively solves these diverse tasks simultaneously
A Methodology for the Assessment of the Urban Heat Island Effect by Exploiting the Urban Archetype Approach
No full textPopulation in urban areas experiences local warming with temperatures higher than in surrounding rural areas due to the Urban Heat Island (UHI) effect, which determines risks for human health, and increases in energy consumption. In the literature, it is reported that accurately quantifying the UHI effect at a wider territorial scale is challenging, due to difficulties in acquiring climatic data at microscale and modelling the drivers of UHI while considering the interactions between buildings and their surroundings.
This work, developed in the framework of the PRIN2022-PNRR CRiStAll (Climate Resilient Strategies by Archetype-based Urban Energy Modelling) project, aims to overcome this research gap by coupling Urban Building Energy Modelling with urban archetypes, representative urban context configurations at microscale derived by varying urban canyon parameters and assuming building archetypes of different climatic zones, use categories, and construction periods.
The methodology presented in the paper is applied to create urban archetypes for the city of Torino (Italy). Key metrics of the urban context are assessed and the UHI effect is evaluated by means of Urban Weather Generator. Energy simulations are then carried out using CitySim Pro to quantify the effect of the UHI on the energy behaviour of buildings at the urban scale. The urban archetype approach is effective for getting outcomes both at a finer spatial resolution, due to the modelling of climatic data at microscale, and with larger spatial coverage, due to the adoption of a bottom-up model that allows mapping of urban areas
Effect of a 2D-Modification of Cs2AgBiBr6 on Nucleation and Contact Formation of Subsequently Deposited Hole Transport Layers as Revealed by In Situ Growth Studies
Full text link: A two-dimensional (2D) perovskite interlayer prepared by modification of a three-dimensional (3D) perovskite absorber with organic ammonium ions such as butylammonium (BA+) or phenethylammonium (PEA+) between the 3D perovskite and contact layers is widely known to significantly improve the performance of perovskite solar cells. This has also been confirmed previously for the lead-free double perovskite absorber Cs2AgBiBr6. In this work, film growth of copper phthalocyanine (CuPc) or pentacene (Pn), used as model hole transport materials (HTM), was investigated. Mimicking solar cell geometry, the HTMs were evaporated onto thin films of 2D perovskites BA4AgBiBr8 or PEA4AgBiBr8, as well as on 3D Cs2AgBiBr6, either in its pristine form or after modification by BA+ or PEA+. The morphology and work function were inspected intermittently with respect to the evaporation of the HTMs by Kelvin probe force microscopy at different average film thicknesses. By these means, the origin of device improvements following a 2D-modification in contact with HTMs, as established earlier, was revealed by analyzing in detail the interface of the HTM with the respective perovskite starting at monolayer coverage and proceeding toward bulk thickness. On modified Cs2AgBiBr6, the energy alignment between the perovskite and the HTM was found to be well confined, and the growth of both HTMs was improved compared to pristine Cs2AgBiBr6. HTM growth occurred more homogeneously and led to layer formation, even at early stages of deposition. For CuPc as HTM, these changes were accompanied by preferential formation of needles in a crystal phase different from that formed on pristine Cs2AgBiBr6, as also detected on 2D PEA4AgBiBr8. Pn formed large dendritic islands on the 2D perovskites as well as on layered terraces formed upon ammonium modification of Cs2AgBiBr6, in contrast to the growth of small grains on pristine Cs2AgBiBr6. Implications of these observed changes in film growth and energy level alignment on the observed contact characteristics with the HTMs in model solar cells are discussed. Insight into the mechanism of improving perovskite-based devices by use of 2D/3D perovskite heterostructures is, thereby, provided by these measurements using CuPc or Pn as model HTMs
Emission reduction potential of hydrotreated vegetable oil (HVO) in a dual-loop EGR diesel engine with fuel-specific optimized calibration
No full textIn the pursuit of carbon neutrality, biofuels offer a viable alternative to reduce net CO2 emissions, as their production absorbs CO2. Hydrotreated vegetable oil (HVO), a second-generation biodiesel, offers several advantages with respect to fatty acid methyl esters (FAME). In particular, HVO can be also utilized pure without significant modifications to current diesel technology. This paper shows the potentialities of using pure HVO in a prototype dual-loop EGR diesel engine derived from a modern Euro 6 latest-generation version. Preliminary experimental tests show appreciable advantages when HVO is used as a drop-in fuel, that is, without any modification to the original diesel-oriented engine calibration. Substantial reductions in HC, CO and soot engine-out emissions are obtained, with variations in NOx primarily depending on the specific engine operating conditions. Nevertheless, the paper shows that even greater benefits can be achieved with dedicated HVO-specific calibrations, optimized using statistical techniques of Design of Experiments (DoE). For instance, a tailored HVO-specific calibration that maximizes NOx reductions could decrease NOx engine-out emissions by approximately 30% at medium-to-high load and as much as 60% at low load, if compared to a diesel-oriented calibration targeting the same objectives. The study also compares other engine-out emissions and noise levels by implementing alternative dedicated calibrations aimed at minimizing CO or brake specific fuel consumption, depending on the operating point considered
Memristance and transmemristance in multiterminal memristive systems
Full text linkMemristive devices represent promising building blocks for the development of next-
generation memory technologies, computing architectures, and neuromorphic systems. In
addition to conventional two-terminal memristive circuits and crossbar array structures,
multiterminal memristive systems, where emergent behaviours arise from the mutual
interaction of numerous memristive elements, have been explored for neuromorphic data
processing and computing applications. In this work, we extend the concept of two-terminal
memristive devices to generic multiterminal memristive systems. Beyond its ability to describe
the specific case of crossbar arrays, the proposed theoretical framework is also applicable to
more complex systems such as self-organizing memristive networks, whose internal state
dynamics depend not only on time-varying input signals but also on the spatial distribution of
the stimulated terminals. After discussing the notion of memristance in multiterminal devices
as the evolution of the system “seen” from the stimulating terminals, we demonstrate that the
two-terminal memristive framework can be generalized to the concept of transmemristance
when additional, non-stimulating electrodes are used to monitor the system’s evolution.
Providing a connection between circuit theory and network science, these concepts are
investigated both analytically and experimentally using a theoretical memristive graph model
and an experimental memristive system based on self-organizing nanowire networks
A Replicable Framework to Drive Business Model Innovation Enabled by Web3: A Case Study in the Agri-Food Sector
Full text linkThis paper investigates how Web3 technologies, such as blockchain, NFTs, and the metaverse, can drive Business Model Innovation (BMI) by enabling new forms of value creation, delivery, and capture. While the strategic potential of Web3 has been widely discussed, there remains a lack of operational tools to guide its implementation in real-world business contexts. To address this gap, we introduce the Web3 Value Exploitation De sign Model (Web3 VEDM), a step-by-step framework grounded in the GUEST methodology. The model is designed to support engineering managers in assessing Web3 readiness, aligning stakeholders, and developing decentralized business models. The framework is empirically validated through a real-world case study in the agri-food sector, offering actionable insights into how organizations can leverage Web3 to transition from centralized to decentralized, participatory ecosystems. The study contributes both theoretically and practically by bridging the gap between conceptual exploration and structured application of Web3 in business transformation
Electrochemical signatures in proton exchange membrane fuel cells: A comprehensive study based on distribution of relaxation times
Full text linkThe impedance response of a proton exchange membrane fuel cell (PEMFC) was analyzed using the Distribution of Relaxation Times (DRT) under varied operating conditions of load, temperature, pressure, stoichiometry, and oxidant type. Six relaxation processes were identified and characterized through their resistance and time constant evolution. A non-linear regression framework quantified their statistical significance and correlations with operating parameters, while reconstruction errors and confidence intervals revealed non-negligible uncertainties affecting interpretation. The highest-frequency contribution appears mainly as a DRT regression artifact, though its resistance still exhibits temperature dependence, possibly linked to proton transport or residual ohmic effects. Among the remaining high-frequency features, one is statistically insignificant, while another shows mixed dependencies, suggesting the superposition of multiple concurrent processes. Mid- and low-frequency contributions vary coherently with temperature, pressure, and load, consistent with charge-transfer and mass-transport phenomena. Overall, the work establishes a quantitative link between operating parameters and internal processes, advancing the diagnostic and predictive capabilities of DRT for PEMFCs
Tools and protocols for buildings sustainability assessment and certification
No full textThis chapter examines tools and protocols for assessing and certifying the sustainability of buildings, with a focus on European and international practices. Directive 2002/91/EC and the evolution of energy certification are explored, with the Energy Performance Certificate at the centre. The circular economy in the built environment, multi-building tools for sustainability, and a practical case study are explored. Life Cycle Assessment is analysed in relation to international standards, systems such as Building Research Establishment Environmental Assessment Method and Leadership in Energy and Environmental Design and environmental benchmarks, highlighting their crucial role in mitigating impacts in the construction sector
Sizing and economic assessment for auxiliar components and grid connection of a MgB2-LH2 hybrid power cable
No full textThe successful integration in the transportation of two very different commodities, namely electricity and liquid hydrogen LH2, in hybrid cables requires several auxiliary components, including storage tanks for hydrogen before and after terminal points, current leads designed for the efficient coupling and decoupling of current-cryogen flow within the transmission line, a pumping system to ensure the effective circulation of the cryogenic fluid and grid connections from the electric power production plant to the grid through the superconducting cable. These components significantly impact on the overall cost structure and are crucial for the potential market adoption of the technology. This study focuses the dimensioning of the auxiliary components through an evaluation of their thermal-hydraulic parameters, followed by an assessment of their effects on overall costs and economic viability. The reference case study is a 30 km-long MgB2 cable, capable of transmitting 10 kA at 30 kV of voltage, cooled by 20 K-liquid hydrogen. This provides essential insights into the potential scalability and sustainability of the proposed system