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An Electrochemical Impedance Spectroscopy (EIS) analysis of a reversible Solid Oxide Cell (rSOC) for its electrochemical characterisation
No full textThe Electrochemical Impedance Spectroscopy (EIS) technique is widely used to characterise electrochemical reaction mechanisms. This technique identifies the main phenomena occurring in an electrochemical device. When dealing with Solid Oxide Electrolysers (SOECs) and Fuel Cells (SOFCs), button cells are generally used for improving their structure, choosing the right electrode materials, and testing manufacturing processes. EIS techniques are then employed to evaluate their performance under different operating conditions. However, larger industrial-sized cells are used for being operated in real test environments, meaning that a larger number of experimental tests on ever-increasing cell area are required to evaluate and assess their performance properly. In such a context, this work aims to cover this research gap by providing EIS spectra as preliminary results of an experimental campaign carried out on a 5x5 cm2 rSOC operating at different conditions in terms of temperature and gas composition. In SOEC mode, an increase in the water content at the fuel electrode leads to unstable conditions and an increase in the polarisation and ohmic resistances. In SOFC mode, a decrease in the hydrogen content at the fuel electrode leads to a maximum increase of the polarisation resistance of 34.17%, while a decrease in the oxygen content at the air electrode leads the system to highly unstable conditions. In both cases, the cell temperature variation leads to a maximum reduction in the ohmic resistance of 12 and 3.8% in SOEC and SOFC modes, respectively
A comparative study of LLMs and NLP approaches for supporting business process analysis
Get PDFThis paper compares two approaches to support Business Process Analysis (BPA) for the construction of a Business Process Knowledge Base (BPKB). The methodology is based on the BPA Canvas metamodel, which starts from the preliminary output of the business analysis (an interview). We focus on the extraction of key elements from the text to build the BPKBcore. We experiment with approaches based on Natural Language Processing (NLP) and Large Language Models (LLMs), using a running example to compare the outcomes with manual annotations. The experiment shows that the LLM-based approach yields better performance, especially with enriched prompts
Analysis of the performances of a solid oxide fuel cell fed by biogas in different plant configurations: An integrated experimental and simulative approach
No full textSolid Oxide Fuel Cells (SOFC) are efficient, modular and fuel-flexible high temperature electrochemical devices. SOFC systems can be coupled to biogas from anaerobic digestion plants to obtain efficient and decentralized CHP systems, maximizing the valorization of biogas in virtuous waste-to-energy schemes. The main challenges for biogas-SOFC plants are related to performance stability and degradation at process level. In this work the performance and stability of an electrolyte supported SOFC single cell (100 cm2) fed with biogas mixtures derived from different integrated biogas-SOFC CHP plant configurations (hot/cold recirculation; UFf 65–85% - obtained from previous simulation work) has been analyzed with an integrated experimental and simulative approach. To support the experimental results, a chemical equilibrium model of the gas conversion processes coupled with the electrochemical conversion route is developed in MATLAB in order to simulate the gas composition at the anode outlet, which is compared and validated with experimental data obtained by Gas Chromatography (GC). Results show that suitable and stable cell performances are obtained while feeding the SOFC samples by biogas (720–800 mV; 0.16–0.2 W/cm2 at 0.25 A/cm2) where the main performance losses are related to steam content - as well as other gas species, deriving from the pre-processing of the biogas. The gas composition and UFf simulation results show good correspondence with the GC data (error range <5% for the matrix gases and <10% for water) highlighting that the SOFC processes under clean biogas can be successfully represented - to a certain extent - by a chemical equilibrium model
Tensile properties of unidirectional thermosetting composites reinforced with ring-spun hybrid yarns including recycled carbon fiber
No full textThe study of composites reinforced with aligned recycled carbon fiber (CF) is gaining increasing attention, particularly in light of the circular economy. Hybrid yarns, among other oriented reinforcements, have gained interest from researchers who have already utilized them to produce unidirectional thermoplastic composites. Nevertheless, the evaluation of unidirectional thermosetting composites reinforced with hybrid yarns is still lacking. This article presents their production, leveraging a recently developed process, and mechanical characterization. The results show that the amount of recycled CF and the number of draw frame doublings within the hybrid yarns affect the tensile properties of the composite, while the thermoplastic fiber has no influence, as also suggested by the main effect plots. Two-way interactions exhibit different behaviors depending on the tensile property considered. Overall, the composite material with the best tensile properties was that reinforced with a ring-spun hybrid yarn consisting of 70% recycled CF, 30% polyamide, and five draw frame doublings
Incident Analysis and Identification of Key Risks During LIB’s Battery Life: the Role of Accidents Databases in the Risk Prevention Actions
No full textThe demands for Li-ion batteries (LIBs) have recently increased exponentially. They are used in a multitude of applications including electric vehicles (EVs), Energy Storage Systems (ESS) and consumer electronics. However, their chemical composition, high energy content and behaviour under abuse conditions pose a significant risk to safety, human health and the environment. This risk is particularly pronounced with the amount of active materials, especially the organic electrolyte and consequently, with the number of cells constituting the battery. To mitigate the risk, critical points throughout the entire life cycle of a lithium battery must be identified. For this purpose, the analysis of accidents occurring around the world acquires a fundamental importance. The evaluation of the main risks associated with the transport, use and storage of LIBs would allow the improvement of specific prevention measures to reduce the risk of fire and explosion during their use and their storage. Additionally, the improvement of safety procedures to manage accidents involving lithium ion batteries should be considered. Furthermore, it enables the updating of legal and technical standards and the development of more reliable storage systems. The aim of this study is to enhance current knowledge on the factors that may trigger fire involving LIBs through the analysis of accidents and recall databases analysis. An Italian database has been developed which includes data on accidents that occurred during the normal use of batteries, as well as those that occurred in storage facilities, during transport and in the disposal of batteries. One example of the reconstruction of data necessary to enhance a database is presented in this work
The TANDEM Euratom project: Context, objectives and workplan
No full textThe TANDEM project is a European initiative funded under the EURATOM program. The project started on September 2022 and has a duration of 36 months. TANDEM stands for Small Modular ReacTor for a European sAfe aNd Decarbonized Energy Mix. Small Modular Reactors (SMRs) can be hybridized with other energy sources, storage systems and energy conversion applications to provide electricity, heat and hydrogen. Hybrid energy systems have the potential to strongly contribute to the energy decarbonization targeting carbon-neutrality in Europe by 2050. However, the integration of nuclear reactors, particularly SMRs, in hybrid energy systems, is a new R&D topic to be investigated. In this context, the TANDEM project aims to develop assessments and tools to facilitate the safe and efficient integration of SMRs into low-carbon hybrid energy systems. An open-source “TANDEM” model library of hybrid system components will be developed in Modelica language which, by coupling, will extend the capabilities of existing tools implemented in the project. The project proposes to specifically address the safety issues of SMRs related to their integration into hybrid energy systems, involving specific interactions between SMRs and the rest of the hybrid systems; new initiating events may have to be considered in the safety approach. TANDEM will study two hybrid systems covering the main trends of the European energy policy and market evolution at 2035's horizon: a district heating network and power supply in a large urban area, and an energy hub serving energy conversion systems, including hydrogen production; the energy hub is inspired from a harbor-like infrastructure. TANDEM will provide assessments on SMR safety, hybrid system operationality and techno-economics. Societal considerations will also be encased by analyzing European citizen engagement in SMR technology safety. The work will result in technical, economic and societal recommendations and policy briefs on the safety of SMRs and their integration into hybrid energy systems for industry, R&D teams, Technical Safety Organizations, regulators, Non-Governmental Organizations and policy makers. The TANDEM consortium will involve 17 partners from 8 European countries (Belgium, Czech Republic, Finland, France, Germany, Italy, Spain, Ukraine). The TANDEM project has the ambition to become a pioneer initiative in Europe in gathering efforts and expertise around development of SMRs integration into hybrid energy systems. The dissemination and the exploitation of the project outcomes as well as the proposed Education & Training activities shall serve as a basis for a number of new R&D and innovation projects addressing the safety issues of SMRs and their integration into hybrid energy systems
Zr:CeO2Buffer by CSD on Ni-W Substrate for Low-Cost Fe(Se,Te) Coated Conductor
No full textAlthough Fe(Se,Te) film shows limited superconducting properties compared to REBCO in terms of critical temperature and critical current density, it represents a potential low-cost alternative to REBCO-based coated conductor applications at low temperature and high field condition. In fact, due to the low deposition temperature and absence of oxygen, materials constraints are less strict and Fe(Se,Te) coated conductor can be realized using a very simplified architecture. A further process simplification is the use of cube-textured substrate combined with a single buffer layer by chemical solution deposition (CSD), which may provide a cheap, vacuum-free route for oriented template fabrication. Zr-doped CeO2/Ni-W templates were realized by CSD and successfully tested with epitaxial Fe(Se,Te) film growth by pulsed laser deposition showing good superconducting properties. Further, a detailed analysis before and after buffer layer deposition using optical, atomic, and scanning electron microscopy, electron backscattered diffraction and Raman and X-ray photoelectron spectroscopy was carried out to relate Zr-doped CeO2 film quality to Ni-W microstructure, morphology, and composition. Results show that 30-nm-thick Zr-doped CeO2 film is effective to prevent Ni diffusion. Further, buffer-layer quality is mainly dependent on the characteristics of individual Ni-W grains
Emergence of Long-Range Angular Correlations in Low-Multiplicity Proton-Proton Collisions
No full textThis Letter presents the measurement of near-side associated per-trigger yields, denoted ridge yields, from the analysis of angular correlations of charged hadrons in proton-proton collisions at s=13 TeV. Long-range ridge yields are extracted for pairs of charged particles with a pseudorapidity difference of 1.4<|Δη|<1.8 and a transverse momentum of 1<2 GeV/c, as a function of the charged-particle multiplicity measured at midrapidity. This Letter extends the measurements of the ridge yield to the low multiplicity region, where in hadronic collisions it is typically conjectured that a strongly interacting medium is unlikely to be formed. The precision of the new low multiplicity results allows for the first direct quantitative comparison with the results obtained in e+e- collisions at s=91 GeV and s=183-209 GeV, where initial-state effects such as preequilibrium dynamics and collision geometry are not expected to play a role. In the multiplicity range
Design Analysis of the DTT Wall Conditioning Systems
No full textWall conditioning plays a key role to assist the discharge start-up and to achieve high-performance plasma scenarios, especially after machine vents and impurity events. This article describes the conditioning systems of the Divertor Test Tokamak (DTT) by focusing on the design of the baking and glow discharge conditioning systems. A general overview of the current design is presented by discussing the main working parameters and the features of each technology under investigation. The integration into the machine is also discussed, by considering the main limitations and interface with other subsystems, particularly with the diagnostic and the pumping system
Characterization and Formation Mechanism of Ag2MoO4 Crystals via Precipitation Method: Influence of Experimental Parameters and Crystal Morphology
No full textAg2MoO4 crystals were prepared by a precipitation method by mixing parent solutions of silver nitrate and sodium molybdate. The effects of experimental parameters such as temperature, concentration, and pH were studied. The samples were found to be crystalline, pure, and monophasic in all cases, except in the case of very low pH. The precipitation leads to the formation of the cubic phase β and no secondary phase is present within the limits of detection of XRD and Raman spectroscopy. However, in some cases, at high temperature and high pH, silver oxide nanoparticles form on the surfaces of the crystals, which create a fluorescence background in the Raman spectra, which is otherwise absent. Analyses with the electron microscope have highlighted that the most common crystalline shape is octahedral, which is the most prevalent at low temperatures and pH around 7, but others are also possible, in particular at high temperatures. No growth occurs after precipitation, so crystals with different appearances form at the same time