1,721,009 research outputs found
EDEN: Novel power-to-power system for enhanced hydrogen storage in solid state
No full textEDEN aims at research, development and validation of a solid-state hydrogen storage technology for specific sector of stationary applications and at support of distributed grid level applications. EDEN realizes a full-scale prototype composed by a storage tank, R-SOC (reversible-Solid Oxide Cell) and an energy recovery solution, which allows overall efficiency improvement and that, is compatible for the use with "polluted" hydrogen. The main objectives of this research project address the development of a new storage material with high hydrogen storage capacity, loaded into a specifically designed storage tank and fully integrated with R-SOC. 10 kg material has been prepared. The intermediate tests demonstrated 7.1 w/w % hydrogen density on the material. Once completed the development and lab characterization, EDEN system prototype has been installed in FBK in Trento, in order to evaluate system performances in real working condition. The demonstration of the technology will be completed in Barcelona, in a selected site controlled by the Barcelona Energy Agency
Output-Only Approach for Finite Element Model Updating of AB-204 Helicopter Blade
No full textThe recent developments in the operative modal analysis made possible a new approach in the estimate of the modal parameters. In fact, they could be evaluated considering only the responses of the structure when subjected to the "natural" excitation during its operative life, output-only analysis. Therefore, this approach could reduce the costs needed for the experimental investigations, since no input measurements are required. Moreover, it takes into consideration the actual loadings and boundary conditions acting on the structure leading to a more accurate identification of the modal parameters. The experimental model so far identified could be considered as reference for a further updating of the structural model. The developed updating procedure, is based on the minimization of an error function, representing the differences between the numerical and experimental model, by means of design variables associated to the finite element model. The error function considered is built from the evaluation of the sensitivity of correlation functions of the Frequency Response Functions, FRFs, to design parameters. In this paper the effectiveness of output-only experimental analysis in both the estimate of the frequency response functions and, then, in the structural updating of the finite element model of an AB-204 helicopter blade is investigated. Specifically, a comparison between the updated finite element models obtained both from the FRFs, gained from the well established experimental modal analysis, and from the output only analysis will be performed
Optimization study of volumetric receivers for high temperature solar plants
No full textNowadays, due to the growing green energy demand, one of the most promising renewable source is represented by solar radiation. Concentrated solar power (CSP) could be an excellent choice, also as alternative technology for centralized energy production at large scale. Within CSP technologies, Central Receiver Towers (CRT) are one of the most interesting applications. CRT consists of a solar tower plant, mirroring surfaces (heliostat) that concentrate sunlight on a receiver and an associated thermodynamic cycle. The solar receiver is a key element of the overall technology and converts the solar radiation into heat, delivering it to a forced flow of air. Two different typologies are investigated in this paper: a porous ceramic absorber and a hierarchical receiver patented by FBK, an independent research institute in Trento, Italy. The purpose of this work is to develop an optimization tool that may generate practical guidelines for the receiver design; this task is performed by studying the potential maximum efficiency as a function of geometry (shape and dimensions) and material properties. The core of this tool is a simplified mono-dimensional model, representing both types of receiver considered in local thermal non equilibrium. The S4 discrete-ordinates approximation is employed, requiring less computational effort and ensuring at the same time accurate simulations. Examining the porous receiver, the optimization results indicate that, with a linear variable porosity, the conversion efficiency increases, for a selected pore diameter and a given thermal conductivity. The optimization of the hierarchical receiver combines four layers, each one coupled with the following one in terms of radiative and conductive heat transfer. The results suggest that the performance is substantially influenced by the behaviour of the first layer. The efficiency can be improved by a proper balance, a better optical efficiency and an enhanced convective transport
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
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
Design and modeling of a hybrid reversible solid oxide fuel cell – organic Rankine cycle
No full textA combined-cogenerative system is here presented and analyzed in order to prove the concept and viability of coupling two of the most promising technologies nowadays available on the market of renewable and storage energy. A model based on reversible Solid Oxide Fuel Cell and Solid Oxide Electrolyzer (rSOFC/SOE) system is coupled with an Organic Rankine Cycle (ORC) system to exploit the waste heat coming from the hydrogen conversion process. The ORC is able to recover a considerable part of the waste heat energy coming from both the power-to-hydrogen and water-to-hydrogen processes. The fuel cell analyzed is able to operate as SOE system producing hydrogen when electric power is available from the grid. The design optimization of the comprehensive layout, however, is nontrivial because there exist many design variables and practical considerations. The model is based on data available from previous experimental campaigns and it is used to complete the design of the layout and to properly size the system’s components. A simplified approach to implement the Steady State (SS) behavior of the whole system is then proposed. Figure 1, the “ideal” flows of the three valuable sources of the system studied (thermal, electric power and hydrogen)
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
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