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The impact of the spatial resolution of vegetation cover on the prediction of airborne pollen concentrations over northern Italy
Full text linkAccurate pollen forecasting models can help the self-management of allergic respiratory diseases. Our study introduces and validates, for the first time, a pollen modelling system covering the Veneto Region (Italy) at the 3 km spatial resolution for 2019. The model simulated the pollen dispersion, diffusion and deposition processes, using vegetation cover (VC) maps, phenological pollen emission algorithms, and meteorological forecasting. We have specifically analysed the influence of the spatial resolution of VC maps on predicted airborne pollen concentrations for alder, birch, olive, grass, and ragweed. Two VC datasets were used: CAMS VC: the European CAMS dataset at ca. 10 km horizontal resolution; detailed VC: high-resolution datasets (from 250 m to 1 km spatial resolution). Predicted daily averaged concentrations obtained with CAMS and detailed VC were compared to the observations collected at 15 monitoring stations using model performance indicators and pollen seasonal-derived parameters. A stratified analysis assessed performance variations in lowland versus mountain environments. The results showed a reduction of the root mean square error (RMSE) for alder and birch pollen using the detailed VC (detailed VC vs. CAMS VC: 15.7 vs. 133.6; 17.8 vs. 52.5 p/m3, respectively), while higher RMSE resulted for grass (24.5 vs. 20.7 p/m3). Similar RMSEs were obtained for olive and ragweed pollen (3.8 vs. 4.0; 3.9 vs. 3.9 p/m3, respectively). Results from the differences in Seasonal Pollen Integrals (SPIn) were consistent with the RMSE patterns. The onset of pollen seasons was more accurately predicted than their end. The general improvement of pollen predictions obtained with the detailed VC was particularly evident in the mountains. Incorporating data from detailed vegetation maps into atmospheric dispersion models has significantly improved predictions for arboreal pollen (alder, birch, olive), especially in complex surfaces where high-resolution input data is crucial
A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
Full text linkThe objective of thermonuclear fusion consists of producing electricity from the coalescence of light nuclei in high temperature plasmas. The most promising route to fusion envisages the confinement of such plasmas with magnetic fields, whose most studied configuration is the tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one of the main potential showstoppers on the route to a commercial reactor. In this work we report how, deploying innovative analysis methods on thousands of JET experiments covering the isotopic compositions from hydrogen to full tritium and including the major D-T campaign, the nature of the various forms of collapse is investigated in all phases of the discharges. An original approach to proximity detection has been developed, which allows determining both the probability of and the time interval remaining before an incoming disruption, with adaptive, from scratch, real time compatible techniques. The results indicate that physics based prediction and control tools can be developed, to deploy realistic strategies of disruption avoidance and prevention, meeting the requirements of the next generation of devices
Design status of the neutron and gamma-ray diagnostics for the Divertor Tokamak Test facility
Full text linkIn the frame of the design activities of the Divertor Tokamak Test (DTT) facility the development of a comprehensive set of neutron and gamma-ray diagnostics is on-going in order to enable measurements of: neutron yield, neutron yield rate, neutron emissivity over a poloidal section through the plasma; neutron emission spectrum; runaway electrons induced bremsstrahlung radiation and gamma-ray emission from reactions between fast ions and plasma impurities. The present paper provides an overview of the DTT neutron and gamma-ray diagnostics and describes the present status of their design including main components and interfaces, detector types and performances
Fabrication of three-dimensional micropatterned hydrophobic surfaces by fused filament fabrication printing technology
No full textIn recent years, the interest in structured hydrophobic surfaces has considerably grown, finding applications in many industrial fields, including aerospace, automotive, and biomedical. Three-dimensional (3D) printing technology is a simple, rapid, and economic process to fabricate structured surfaces based on neat polymers and composite materials, allowing working with a wide variety of plastic materials. The manufactured surfaces show a roughness depending on the printing design and the printing resolution: this characteristic is ideal to achieve superhydrophobic properties. Furthermore, patterned surface structures can be printed by fused filament fabrication (FFF), so increasing the hydrophobic character of the samples; indeed, micro- and nanosurface structures are required to make a hydrophobic surface. In this study, 3D micropatterned textures of pillars were printed by FFF using polylactide (PLA) and polypropylene (PP) as polymer filaments and PLA/carbon nanotubes (PLA/CNTs) and PP/carbon fibers (PP/CF) as composite filaments. Morphologies of printed specimens were analyzed by optical microscopy and scanning electron microscopy. Good correspondence was found between pillar dimensions and edge-edge pillars distance of computer aided design (CAD) and composites 3D-printed samples. Their wettability was evaluated by static contact angle (CA) measurements. Results clearly show a significant increase of water CA values up to 50% in all micropatterned samples with respect to flat surfaces. This improvement was achieved by surface microstructuring without the use of nanoparticles and/or chemical treatment
Observation of magnetic islands in tokamak plasmas during the suppression of edge-localized modes
Full text linkIn tokamaks, a leading platform for fusion energy, periodic filamentary plasma eruptions known as edge-localized modes occur in plasmas with high-energy confinement and steep pressure profiles at the plasma edge. These edge-localized modes could damage the tokamak wall but can be suppressed using small three-dimensional magnetic perturbations. Here we demonstrate that these magnetic perturbations can change the magnetic topology just inside the steep gradient region of the plasma edge. We identify signatures of a magnetic island, and their observation is linked to the suppression of edge-localized modes. We compare high-resolution measurements of perturbed magnetic surfaces with predictions from ideal magnetohydrodynamic theory where the magnetic topology is preserved. Although ideal magnetohydrodynamics adequately describes the measurements in plasmas exhibiting edge-localized modes, it proves insufficient for plasmas where these modes are suppressed. Nonlinear resistive magnetohydrodynamic modelling supports this observation. Our study experimentally confirms the predicted role of magnetic islands in inhibiting the occurrence of edge-localized modes. This will be beneficial for physics-based predictions in future fusion devices to control these modes
Development and preliminary validation of TIFONE, a design-oriented code for the inter-wrapper flow and heat transfer in liquid-metal-cooled reactors
Full text linkAmong the goals of the core design for Lead-cooled Fast Reactors (LFRs) exploiting the closed Sub-Assembly (SA) option, cold by-passes should be minimised and excessive thermal gradients among opposite faces of the assembly ducts prevented. To this aim, given an Inter-Wrapper (IW) gap determined by the core thermo-mechanical design, a suitable coolant flow outside the assemblies themselves must be guaranteed. Moreover, the designer has the opportunity to introduce flow restrictions to tune the intra-wrapper flow fraction at the SA level, possibly allowing to reduce temperature differences at the outlet of the assemblies. Therefore, the designer needs to be aware of the axial and radial temperature profiles of the IW coolant throughout the whole core (i.e., including all core SAs), as well as of the axial and perimetrical temperature profiles of the wrapper of each SA. Notably, the possibly different temperature values of each side of the wrapper itself should be assessed, since they could induce SA bowing. To address these needs, a Design-Oriented Code (DOC), TIFONE, was developed and verified in compliance with current best practices in terms of software quality assurance. TIFONE adopts the sub-channel method, leading to a sufficient level of spatial resolution while retaining the key features of a DOC, namely equilibrium, a low computational time and a clear application domain. The paper describes the code structure, governing equations and solution method. It also reports the preliminary validation of TIFONE against data from inter-wrapper flow and heat transfer experiments performed in the frame of the SESAME project at the THESYS loop within the KALLA laboratory, confirming the code capability to reproduce the measured data in its anticipated validity domain
Shutdown dose rate experiment at JET during DTE2
No full textThe EUROfusion activities on the technological exploitation of deuterium–tritium (DT) operation at JET (started within the work package JET3 and continued under PrIO) were established to maximize the scientific and technological return of DTE2 campaign occurred in the second part of 2021. In particular, the aim of the NEXP sub-project was to take advantage of the expected significant neutron production during DTE2 to validate the numerical tools used for neutron streaming and shutdown dose rate (SDR) calculation for ITER through the comparison between numerical predictions and measurements. In the frame of SDR activity, a dosimetry system to measure the dose rate and based on some ionization chambers (ICs) was installed in the torus hall and upgraded both hardware and software since 2015 by exploiting the previous DD and TT campaigns. Two spherical 1-L air-vented ICs had been installed in some ex-vessel positions close to the horizontal ports of the tokamak in octants 1 and 2 and a third IC, suitable for higher dose rates, was then added in octant 1. As for SDR calculation, numerical tools employed rely on MCNP code for radiation transport and in this regard the MCNP model has been updated to include the last detector installed in octant 1. The present work is dedicated to the analysis of dose rate measurements carried out during DTE2 in the inter-pulse periods and at the shutdown. Influence quantities and error sources are analyzed to calculate the dose rate from raw signal and experimental uncertainty. Some experimental points are chosen and employed for a preliminary comparison with numerical predictions obtained from three-dimensional simulations with Advanced D1S tool. The results are presented and discussed with the major objective to contribute to the optimization of the planned SDR code validation
Multi-elemental analysis of commercial wheat flours by ICP-MS triple quadrupole in function of the milling degree
Full text linkThis preliminary study is focused on an elemental analysis of 60 samples of different commercial grains' flour, including various typologies of refined product, researching transition metals and trace elements. All the samples were first digested with a microwave digestion system and then analyzed by a triple quadrupole (TQ) inductively coupled plasma mass spectrometer (ICP-MS-QQQ) located in a Clean Room ISO class 6. The minimum value of most of the elements (Li, Be, Na, Ca, V, Cr, Mn, Fe, Co, Ni, Zn, Ga, As, Se, Rb, Sr) are in the wheat flour “00” type and in the wheat flour “0” type (B, Na, Mg, Al, Cu, Ag, Cd, In, Cs, Pb, Bi). On the opposite, the maximum value of these elements is found in whole wheat flour (B, Mg, K, Ca, Mn, Zn, Ga, Rb, Sr, Ba) and in the wheat flour “0” type (Na, Al, V, Cr, Fe, Co, Ni, As). Relating rare-earth elements (REE), all of them show value similar to each other and not under the detection limits thanks to the use of a TQ in the clean room. The final aim is to create a large database, with a high data bank and easily enlargeable, that could be used in future to analyze unknown flour samples and to set up traceability analysis. The purpose of this work is to find some trends of analyzed elements in function of different parameters, such as milling degree or geographical origin, also with a statistical point of view
The core-edge integrated neon-seeded scenario in deuterium-tritium at JET
Get PDFThis paper reports the first experiment carried out in deuterium-tritium addressing the integration of a radiative divertor for heat-load control with good confinement. Neon seeding was carried out for the first time in a D-T plasma as part of the second D-T campaign of JET with its Be/W wall environment. The technical difficulties linked to the re-ionisation heat load are reported in T and D-T. This paper compares the impact of neon seeding on D-T plasmas and their D counterpart on the divertor detachment, localisation of the radiation, scrape-off profiles, pedestal structure, edge localised modes and global confinement
JET machine operations in T&D-T
Full text linkJET, the world's largest operating tokamak with unique Be/W wall and tritium handling capability, completed a Deuterium-Tritium (D-T) campaign in 2021 (Maggi et al 29th Fusion Energy Conf.) following a decade of preparatory experiments, dedicated enhancements, technical rehearsals and training (Horton et al 2016 Fusion Eng. Des. 109-111 925). Operation with tritium raises significant technical, safety and scientific challenges not encountered in standard protium or deuterium operation. This contribution describes the tritium operational requirements, pulses and technical preparations, new operating procedures, lessons learned and details on the achieved operational availability and performance. The preparation and execution of the recent JET tritium experiments benefitted from the previous experience in 1991 (Preliminary Tritium Experiment), 1997 (DTE1 campaign) and 2003 (Trace Tritium Campaigns) and consisted of the following five phases: technical rehearsals and scenario preparation, tritium commissioning, 100% tritium campaign, D-T campaign (DTE2), tritium clean-up. Following the clean-up JET resumed normal operation and is currently undertaking a further D-T campaign (DTE3)