1,720,971 research outputs found
Development of a numerical model for PEM electrolysers for the implementation of a simulation-based Digital Twin.
No full textThe green hydrogen production through electrolysis is a critical pathway toward achieving carbon neutrality, as it allows for the production of green hydrogen without emissions.
Regarding the hydrogen production different aspects of water electrolysers should be analyzed, including efficiency, operating conditions, investment cost, durability, hydrogen purity, infrastructure development and technology maturity.
Maintaining optimal operating conditions, such as temperature, pressure and humidity of the stack membranes, can significant enhance the durability and the efficiency of the WE system resulting in less degradation of the components, high-quality hydrogen output and higher cost-effectiveness of hydrogen production.
For example in a Proton Exchange Membrane (PEM) water electrolyser, an increase from 60 °C to 80 °C of operating cell temperature at equal conditions (power density: 1 A/cm2), can lead to a reduction up to 75% of the operational time to reduce membrane thickness by 50%. The membrane thickness is strongly correlated with the gas cross over and therefore affects the lifetime of the electrolyser.
Moreover, during the electrolyser lifetime, the system is characterized by start-up and shut down cycle phases leading to a reduced lifetime of the stack component due to the introduced thermal stresses.
An optimal management of hydrogen productio is therefore considered essential. For instance instead of frequently switching between operational and shutdown phases, a reduction of electrolyser load helps to minimize the system degradation extending its lifespan.
The degradation of electrolyser systems significantly influences the cost-efficiency of green hydrogen production. Mitigating the degradation, extends component lifespan, preserves optimal operational performance, and improves the competitiveness of electrolysis technology. Efficient management of electrolyser degradation is essential to ensure the economic feasibility of hydrogen production, especially in large-scale industrial plants.
The work is set within the broader context of the development of Hydrogen Valleys, initiatives that aim to create integrated ecosystems where hydrogen is produced, stored, and used. Specifically, the focus is on producing hydrogen using small-scale electrolysers, which are particularly suitable for localized production and flexible deployment. This approach supports the transition toward a decentralized energy system while contributing to the sustainability goals established by the EU commission
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Development of a decision-oriented tool for operational management of a PEMWE
No full textThe hydrogen production via electrolysis represents a key pathway for decarbonizing shipping and contributing to carbon neutrality goals, as it enables the generation of green hydrogen with potential zero emissions. The electrolysers system management directly impacts on the cost-effectiveness of green hydrogen production and thus enhancing the overall competitiveness of the electrolysis technology.
In the context of Hydrogen Valleys development hydrogen production via Proton Exchange Membrane Water Electrolysis (PEMWE) is gaining increasing attention, with approximately 20% more facilities adopting PEM technology compared to alkaline ones, especially in renewable energy sources (RES) powered plants.
However, in large-scale industrial applications, for a determined market demand and in the case of coupling PEMWE with RES, optimal management strategies for hydrogen production are required to ensure effective operation under dynamic power supply conditions. From literature, it is highlighted that in order to ensure the economic viability of hydrogen production, a holistic approach that consider all interconnected variables of PEMWE under dynamic operation should be considered. In this context, data-driven approaches, such as Machine Learning and Digital Twins models, will play a key role in managing electrolysis systems under dynamic power conditions, enabling strategic decisions to be made for electrolyser operation.
This research is to develop a comprehensive numerical model of a PEMWE offering insights into system management under variable load conditions driven by RES availability, electricity market price, and weekly hydrogen demand, while avoiding operational conditions that could lead to increase the energy intensity of the process. The work it is placed in a wider framework in which the resulting datasets, obtained through the model numerical simulation, are used to train a physics-based Digital Twin
In Situ Study of Nanoporosity Evolution during Dealloying AgAu and CoPd by Grazing-Incidence Small-Angle X-ray Scattering
Full text linkElectrochemical dealloying has become a standard technique to produce nanoporous network structures of various noble metals, exploiting the selective dissolution of one component from an alloy. While achieving nanoporosity during dealloying has been intensively studied for the prime example of nanoporous Au from a AgAu alloy, dealloying from other noble-metal alloys has been rarely investigated in the scientific literature. Here, we study the evolution of nanoporosity in the electrochemical dealloying process for both CoPd and AgAu alloys using a combination of in situ grazing-incidence small-angle X-ray scattering (GISAXS), kinetic Monte Carlo (KMC) simulations, and scanning transmission electron microscopy (STEM). When comparing dealloying kinetics, we find a more rapid progression of the dealloying front for CoPd and also a considerably slower coarsening of the nanoporous structure for Pd in relation to Au. We argue that our findings are natural consequences of the effectively higher dealloying potential and the higher interatomic binding energy for the CoPd alloy. Our results corroborate the understanding of electrochemical dealloying on the basis of two rate equations for dissolution and surface diffusion and suggest the general applicability of this dealloying mechanism to binary alloys. The present study contributes to the future tailoring of structural size in nanoporous metals for improved chemical surface activity
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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