1,720,955 research outputs found
Development of a Novel Snom Probe for in Liquid Biological Samples
Get PDFThis work is focused on the study and implementation of a novel method for the development of probes for Scanning Near-field Optical Microscopy (SNOM). The proposed approach is based on the mechanical impedance matching between the optical fiber tip and the resonating tuning fork. This methodology allowed an increase of the quality factor of the piezoelectric resonator used as atomic force transducer in the SNOM probe, thus increasing its overall sensitivity. This kind of probes are often used on biological soft samples in liquid. The presence of water medium has a strong dumping effect on probe sensitivity. Experimental validation of the proposed methodology showed an increase of robustness of SNOM probes also for in liquid samples
Experimental characterization of an anion exchange membrane electrolyser and ancillary component
No full textLAUREA MAGISTRALESecondo l'ultimo report annuale dell'agenzia internazionale dell'energia, l'idrogeno occuperà un ruolo fondamentale nella transizione energetica per rispettare gli obiettivi europei al 2050 per la neutralità carbonica. Gli elettrolizzatori alimentati tramite energia da fonti rinnovabili si candidano ad un ruolo primario nel medio periodo. Questo lavoro di tesi, svolto presso il Laboratorio di Energy Conversion and Storage (LabX) del Dipartimento di Energia del Politecnico di Milano, ha l'obiettivo di caratterizzare le perfomance di un elettrolizzatore con membrana a scambio anionico. Questa tecnologia si pone nel mezzo tra le più note elettrolisi di tipo PEM e alcalina, cercando di sfruttare i vantaggi di entrambe. Nella prima fase ci si è concentrati nella ricerca di malfunzionamenti e anomalie del sistema, mentre in secondo luogo nell'analisi delle performance attraverso il calcolo dell'efficienza elettrica, dello stack e dell'intero sistema agli effetti esterni. La campagna sperimentale ha permesso di individuare alcune anomalie e implementare delle correzioni. Nei test finali, il sistema lavora correttamente, tuttavia l'efficienza è minore di quella attesa (60%), assestandosi attorno a un valore massimo del 42.5%.
Un secondo obiettivo di questo lavoro è la progettazione preliminare di un misuratore basato sull'effetto Venturi che possa essere facilmente installabile in serie a elettrolizzatori di piccola taglia. Non esistendo una normativa specifica per questo componente ci si è affidati per quanto possibile alle esistenti normative sul tema per componenti di maggiori dimensioni. Lo strumento necessiterà di una calibrazione con un misuratore già presente in modo da costruire la correlazione della curva perdite di carico vs portata volumetrica per poi essere utilizzato in solitaria. L'elaborato si conclude con il calcolo dell'errore di misura che questo nuovo strumento potrebbe garantire.According to the latest annual report of the International Energy Agency, hydrogen will play a key role in the energy transition to meet the European objectives for 2050 for carbon neutrality. Electrolysers powered by energy from renewable sources are candidates for a primary role in the medium term. This thesis work, carried out at the Energy Conversion and Storage Laboratory (LabX) of the Department of Energy of the Politecnico di Milano, has the objective of characterizing the performance of an anion exchange membrane electrolyser. This technology tries to exploit the advantages of the more known and present in the market PEM and Alkaline electrolysis. In the first phase, the focus of the work is testing the machine, aiming at creating a performance map, while identifying potential anomalies in the operation; in the second phase the goal is the analysis of the performance through the calculation of the electrical efficiency, stack efficiency and the one of the whole system at the external effects. The experimental campaign allowed to identify critical issues and implement corrections; in the final tests, the stack performs properly, but the overall electric efficiency appears lower than the expected 60%, with a maximum system efficiency around 42.5%.
A second objective of this work is the preliminary design of a meter based on the Venturi effect that can be easily installed in series with small size electrolysers. Since there is no specific regulation for this component of low dimensions, the reference used is the existing regulations on the subject for larger devices. The instrument will require a calibration with another meter in order to build the correlation curve of the pressure drop vs volumetric flow rate and then to be used alone on the line. The paper concludes with the calculation of the measurement error that this new instrument could guarantee
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
The Coordinated Power Control of Flexible DC Microgrids in Sustainably Optimized Yacht Marinas
Get PDFNowadays, the industrial world is undergoing a disruptive transformation towards more
environmentally sustainable solutions. In the blue economy, this new approach is not only expressed
in the domain of actual vessels, but also in the development of charging infrastructure, displaying a
notable transition towards more eco-friendly solutions. The key focus lies in adopting flexible power
systems capable of integrating renewable energy sources and storage technologies. Such systems play
a crucial role in enabling a shift towards low-emission maritime transport. The emissions reduction
goal extends beyond onboard shipboard distribution systems, encompassing also the design of supplying
platforms and marinas. This study explores the implementation of a controlled DC microgrid
tailored to efficient management of power flows within a yacht marina. Once having established the
interfaces for the vessels at berth, the integration between the vessels, the onshore photovoltaic plant
and the battery storage unit is made possible thanks to the coordinated management of multiple
power converters. The overarching goal is to curtail reliance on external energy sources. Within
this DC microgrid framework, a centralized controller assumes a pivotal role in orchestrating the
power sources and loads. This coordinated management is essential to achieve sustainable operations,
ultimately leading to the reduction of emissions from both ships and onshore power plants
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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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