12064 research outputs found
Sort by
Studying the interaction between charm and light-flavor mesons
Get PDFThe two-particle momentum correlation functions between charm mesons (D∗± and D±) and charged light-flavor mesons (π± and K±) in all charge combinations are measured for the first time by the ALICE Collaboration in high-multiplicity proton-proton collisions at a center-of-mass energy of s=13 TeV. For DK and D∗K pairs, the experimental results are in agreement with theoretical predictions of the residual strong interaction based on quantum chromodynamics calculations on the lattice and chiral effective field theory. In the case of Dπ and D∗π pairs, tension between the calculations including strong interactions and the measurement is observed. For all particle pairs, the data can be adequately described by Coulomb interaction only, indicating a shallow interaction between charm and light-flavor mesons. Finally, the scattering lengths governing the residual strong interaction of the Dπ and D∗π systems are determined by fitting the experimental correlation functions with a model that employs a Gaussian potential. The extracted values are small and compatible with zero
Signature of f(R) gravity via Lemaître–Tolman–Bondi inhomogeneous perturbations
Get PDFWe analyze inhomogeneous cosmological models in the local Universe, described by the Lemaître–Tolman–Bondi (LTB) metric and developed using linear perturbation theory on a homogeneous and isotropic Universe background. Focusing on the different evolution of spherical symmetric inhomogeneities, we compare the ΛLTB model, in which the cosmological constant Λ is included in the LTB formalism, with inhomogeneous cosmological models based on fR modified gravity theories viewed in the Jordan frame. We solve the system of field equations for both inhomogeneous cosmological models adopting the method of separation of variables: we integrate analytically the radial profiles of local perturbations, while their time evolution requires a numerical approach. The main result of the analysis concerns the different radial profiles of local inhomogeneities due to the presence of a non-minimally coupled scalar field in the Jordan frame of fR gravity. While radial perturbations follow a power-law in the ΛLTB model, Yukawa-like contributions appear in the fR theory. Interestingly, this latter peculiar behavior of radial profile is not affected by the choice of the fR functional form. The numerical solution of time-dependent perturbations exhibits a non-diverging profile. This work suggests that investigations about local inhomogeneities in the late Universe may allow us to discriminate if the present cosmic acceleration is caused by a cosmological constant term or a modified gravity effect
Laser-induced breakdown spectroscopy for helium detection in beryllium coatings
Get PDFLaser Induced Breakdown Spectroscopy (LIBS) method is considered to be a promising tool for analyzing the retention of hydrogen isotopes (D and T) and helium (He) on the first walls and divertor regions of future fusion reactors. Helium will be produced in DT reactions but could also be used in the initial non-nuclear phases of DEMO concepts. The present study investigates the He detection by LIBS method in the Be coatings simulating the deposits on the divertor plasma-facing components of JET while the results are also relevant for He detection in the deposits of other wall materials. The study was carried out in a vacuum vessel filled with 2–40 mbar argon background gas. It was shown that 2.8 at. % of He was confidently detectable by LIBS at optimized measurement conditions and the estimated limit of detection at used experimental conditions is approximately 0.7 at. %. The intensity of the He emission line at 587.56 nm was the strongest at the center of the laser-induced plasma plume. The He line intensity increased with the pressure of Ar gas but the broadening of the He line and the increase of the background emission and noise set an upper limit to the Ar background pressure usable for He detection. The application of the calibration-free LIBS procedure resulted in the overestimation of the He/Be ratio by several orders of magnitude. The overestimation can be explained by the deviation of LIBS plasma from the local thermodynamic equilibrium, which is caused by the very high excitation energy of He atoms
Microalgae production in an industrial-scale photobioreactors plant: A comprehensive Life Cycle assessment
Get PDFMicroalgae cultivation provides multiple opportunities to produce valuable bioproducts, but greater clarity must be achieved regarding the real sustainability of current technologies. Numerous life cycle assessment (LCA) studies have been conducted so far. However, most of them were based on literature data and/or extrapolations of lab-scale results, while only a few studies used primary data from pilot or full-scale microalgal plants. Moreover, the obtained results showed great variability, leaving the debate on microalgae sustainability fully open. This work presents a thorough LCA based on primary data from an industrial-scale microalgal facility located in Caltagirone, Italy. The plant is based on vertically-stacked horizontal photo bioreactors (total volume of 40.4 m3 ) installed in a greenhouse and has a capacity of 1200 kgDW/y (Chlorella vulgaris). A cradle-to-gate assessment was performed with the functional unit of 1 kgDW biomass, including operational and infrastructural data. The results emphasized the key role in the generation of potential impacts played by cultivation among process stages and by chemicals (nutrients and cleaning agents) and electricity (mainly for agitation and thermoregulation) among flow types. In comparison with studies from the literature, the analysed microalgal plant has an intermediate environmental performance (e.g., global warming potential of 153 kg CO2,eq/ kgDW). This result is encouraging, as it comes from a reliable assessment built on full-scale pri mary data. On the other hand, it highlights the need to explore alternative strategies (e.g., in dustrial symbiosis and circular bioeconomy) to reduce the environmental footprint of the process and enhance its economic attractiveness
Towards the design of a hydrogen-powered ferry for cleaner passenger transport
Get PDFThe maritime transportation sector is a large and growing contributor of greenhouse gas and other emissions. Therefore, stringent measures have been taken by the International Maritime Organization to mitigate the environmental impact of the international shipping. These lead to the adoption of new technical solutions, involving clean fuels, such as hydrogen, and high efficiency propulsion technologies, that is, fuel cells. In this framework, this paper proposes a methodological approach aimed at supporting the retrofit design process of a car-passenger ferry, operating in the Greece's western maritime zone, whose conventional powertrain is replaced with a fuel cell hybrid system. To this aim, first the energy/power requirements and the expected hydrogen consumption of the vessel are determined basing on a typical operational profile, retrieved from data provided by the shipping company. Three hybrid powertrain configurations are then proposed, where fuel cell and batteries are balanced out according to different design criteria. Hence, a new vessel layout is defined for each of the considered options, by taking into account on-board weight and space constraints to allocate the components of the new hydrogen-based propulsion systems. Finally, the developed vessel configurations are simulated in a virtual towing tank environment, in order to assess their hydrodynamic response and compare them with the original one, thus providing crucial insights for the design process of new hydrogen-fueled vessel solutions. Findings from this study reveal that the hydrogen-based configurations of the vessel are all characterized by a slight reduction of the payload, mainly due to the space required to allocate the hydrogen storage system; instead, the hydrodynamic behavior of the H2 powered vessels is found to be similar to the one of the original Diesel configuration; also, from a hydrodynamic point of view, the results show that mid load operating conditions get relevance for the design process of the hybrid vessels
Towards Sustainability and Energy Efficiency Using Data Analytics for HPC Data Center
Get PDFHigh-performance computing (HPC) in data centers increases energy use and operational costs. Therefore, it is necessary to efficiently manage resources for the sustainability of and reduction in the carbon footprint. This research analyzes and optimizes ENEA HPC data centers, particularly the CRESCO6 cluster. The study starts by gathering and cleaning extensive datasets consisting of job schedules, environmental conditions, cooling systems, and sensors. Descriptive statistics accompanied with visualizations provide deep insight into collated data. Inferential statistics are then used to investigate relationships between various operational variables. Finally, machine learning models predict the average hot-aisle temperature based on cooling parameters, which can be used to determine optimal cooling settings. Furthermore, idle periods for computing nodes are analyzed to estimate wasted energy, as well as for evaluating the effect that idle node shutdown will have on the thermal characteristics of the data center under consideration. It closes with a discussion on how statistical and machine learning techniques can improve operations in a data center by focusing on important variables that determine consumption patterns
Sustainable strategies: Nature-based solutions to tackle antibiotic resistance gene proliferation and improve agricultural productivity and soil quality
No full textThe issue of antibiotic resistance is now recognized by the World Health Organisation (WHO) as one of the major problems in human health. Although its effects are evident in the healthcare settings, the root cause should be traced back to the One Health link, extending from animals to the environment. In fact, the use of organic fertilizers in agroecosystems represents one, if not the primary, cause of the introduction of antibiotics and antibiotic-resistant bacteria into the soil. Since the concentrations of antibiotics introduced into the soil are residual, the agroecosystem has become a perfect environment for the selection and proliferation of antibiotic resistance genes (ARGs). The continuous influx of these emerging contaminants (i.e., antibiotics) into the agroecosystem results in the selection and accumulation of ARGs in soil bacteria, occasionally giving rise to multi-resistant bacteria. These bacteria may harbour ARGs related to various antibiotics on their plasmids. In this context, these bacteria can potentially enter the human sphere when individuals consume food from contaminated agroecosystems, leading to the acquisition of multi-resistant bacteria. Once introduced into the nosocomial environment, these bacteria pose a significant threat to human health. In this review, we analyse how the use of digestate as an organic fertilizer can mitigate the spread of ARGs in agroecosystems. Furthermore, we highlight how, according to European guidelines, digestate can be considered a Nature-Based Solution (NBS). This NBS not only has the ability to mitigate the spread of ARGs in agroecosystems but also offers the opportunity to further improve Microbial-Based Solutions (MBS), with the aim of enhancing soil quality and productivity
Impianto geotermico sperimentale a bassa entalpia presso il C.R. ENEA-Casaccia. Caratterizzazione termica stagionale, assemblaggio del circuito di prova, risultati del monitoraggio
Get PDFL’attività descritta nel presente report è parte del progetto di ricerca, relativo al Piano Triennale di realizzazione 2019-2021 della Ricerca di Sistema Elettrico Nazionale, linea di attività 1.7 “Tecnologie per la penetrazione efficiente del vettore elettrico negli usi finali”. Nello specifico, l’attività in oggetto è la L.A. 3.24, contenuta nel WP3. Nel terzo anno, l’attività è stata incentrata sullo studio e la caratterizzazione termica stagionale del campo geosonde. Per la difficoltà a reperire alcune componenti dell’impianto, causata dalla situazione pandemica, l’assemblaggio del circuito di prova ha subìto ritardi, e quindi il monitoraggio dei valori termometrici all’interno dei pozzi è stato effettuato a circuito spento. Tutti i dati mensili di temperatura dei quattro pozzi sono stati confrontati con i dati del mese di maggio del pozzo 1, in quanto risente ancora delle variazioni di temperatura indotte durante il test di risposta termica (GRT) effettuato il 15 aprile 2021. Sulla base dei dati di temperatura è stato possibile estrapolare la curva di conducibilità termica sperimentale della successione stratigrafica. Inoltre, con l’utilizzo della simulazione termica computazionale si è ricostruita l’alterazione del campo termico indisturbato del terreno sotto l’azione del geoscambio sonde-terreno. Successivamente, il confronto tra i dati climatici annuali registrati dalle stazioni meteorologiche all’interno del C.R. Casaccia con le temperature rilevate direttamente dalle fibre ottiche ha consentito di determinare la profondità fin dove si risente dell’irraggiamento solare nei quattro pozzi. Sono stati calcolati i valori di resistenza termica equivalente dello scambiatore a terreno, ed è stato descritto il funzionamento dell’impianto, le sue componenti, gli strumenti di controllo e di monitoraggio.The activity described in this report is part of the research project, related to the 2019-2021 ThreeYear Implementation Plan of the National Electricity System Research, activity line 1.7 “Tecnologie per la penetrazione efficiente del vettore elettrico negli usi finali”. Specifically, this activity is L.A. 3.24, contained in WP3. In the third year, the activity focused on the study and seasonal thermal characterisation of the geosonde field. Due to the difficulty in finding part of the plant components, caused by the pandemic situation, the assembly of the test circuit was delayed and therefore the monitoring of the thermometric values inside the wells was carried out while the circuit was switched off. All monthly temperature data of the four wells were compared with the May data of well 1, as it was still affected by the temperature variations induced during the thermal response test (GRT) carried out on 15 April 2021. Based on the temperature data, it was possible to extrapolate the experimental thermal conductivity curve of the stratigraphic succession. In addition, with the use of computational thermal simulation, the alteration of the undisturbed thermal field of the ground under the action of probe-soil geo-exchange was reconstructed. Subsequently, the comparison of the annual climatic data recorded by the meteorological stations in the C.R. Casaccia with the temperatures measured directly by the optical fibres made it possible to determine the depth to which solar radiation is detected in the four wells. The equivalent thermal resistance values of the ground heat exchanger were calculated, and the functioning of the plant, its components, control, and monitoring instruments were also described
Genetic algorithm for multilayer shield optimization with a custom parallel computing architecture
Get PDFThis paper introduces a novel architecture for optimizing radiation shielding using a genetic algorithm with dynamic penalties and a custom parallel computing architecture. A practical example focuses on minimizing the Total Ionizing Dose for a silicon slab, considering only the layer number and the total thickness (additional constraints, e.g., cost and density, can be easily added). Genetic algorithm coupled with Geant4 simulations in a custom parallel computing architecture demonstrates convergence for the Total Ionizing Dose values. To address genetic algorithm issues (premature convergence, not perfectly fitted search parameters), a Total Ionizing Dose Database Vault object was introduced to enhance search speed (data persistence) and to preserve all solutions’ details independently. The Total Ionizing Dose Database Vault analysis highlights boron carbide as the best material for the first layer for neutron shielding and high-Z material (e.g., Tungsten) for the last layers to stop secondary gammas. A validation point between Geant4 and MCNP was conducted for specific simulation conditions. The advantages of the custom parallel computing architecture introduced here, are discussed in terms of resilience, scalability, autonomy, flexibility, and efficiency, with the benefit of saving computational time. The proposed genetic algorithm-based approach optimizes radiation shielding materials and configurations efficiently benefiting space exploration, medical devices, nuclear facilities, radioactive sources, and radiogenic devices
“Hearts of gold” (Cuori d'oro): The case study of the leather corami of Palazzo Chigi in Ariccia
Get PDFIn this work we present the results obtained by different technical analysis in order to perform the characterization of the chromatic richness, the employed materials and the iconographic elements of different fragments of decorated and gilded leather corami coming from the archive of Palazzo Chigi of Ariccia (Rome) and employed, during the 17th century, as wallcoverings. Different microscopic and spectroscopic analyses have been performed by means of Ion Beam Analysis (IBA) and Macro Area X-Ray Fluorescence (MA-XRF) techniques available at the INFN LABEC ion beam laboratory in Florence and the Scanning Electron Microscopy-Energy Dispersive X-ray Analysis (SEM-EDX) of the Superconductivity Laboratory of the ENEA Frascati Research Center. The results aim to provide the scholar information about the manufacturing process and the materials employed for the production of these peculiar artefacts, also in order to plan the best and most appropriate conservation protocol. In particular, thanks to the SEM-EDX analysis it has been possible to characterize the layered structure of the samples and, specifically, the interface between the leather of the substrate, the metal foil of the so called meccatura and between these and the overlying pictorial layer. The IBA and MA-XRF techniques has helped in characterizing the painting palette employed while IBA has allowed to determine the conservation condition of the silver layer with the hypothesis of the incorporation of the silver leaf into the organic compound of the mecca as its main deterioration phenomena. These complementary techniques provide, therefore, a comprehensive understanding of the materials and iconographic elements of these leather-based artefacts, which is essential for their preservation and restoration as well as they contribute to a better understanding of the deterioration processes they incur