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Litiumioniakkujen diagnostiikka
No full textLithium-ion batteries are already widely used in various applications from portable electronics to electric vehicles. The biggest advantage of Li-ion batteries compared to other battery technologies is its high energy density. However, high price and risk of thermal runaway in case of electrical or mechanical abuse have restricted the commercialization of Li-ion batteries. Battery diagnostics plays a key role in safe and efficient use of Li-ion batteries. With comprehensive monitoring of the battery the degradation in the cell can be detected and the battery operated in a safe and efficient manner.
In this thesis, a literature survey on existing Li-ion battery diagnostic methods was carried out. That includes methods for estimating the state of charge (SOC), state of health (SOH) and remaining useful life of the battery.
Two diagnostic methods were implemented and tested in this thesis: internal battery temperature estimation based on electrochemical impedance spectroscopy (EIS) and battery SOH estimation using differential analysis and support vector regression (SVR). Experimental data from lithium iron phosphate (LFP) cells was used. A clear change in the EIS results as a function of cell temperature was detected and the working principle of the internal battery temperature estimation method was confirmed. The SVR method proved to be an exact and robust method for fitting smooth curve to the measurement data, although quite sensitive to selecting proper parameters. Two clear peaks were detected in the incremental capacity curves generated with differential analysis, which corresponds to the results in the literature. Except for the beginning of the cell aging, the height of the peaks decreases as the capacity of the cell decreases. This correlation can be utilized for battery SOH estimation, but further research is needed to review the accuracy and reliability of the method.Litiumioniakkuja käytetään jo laajalti erilaisissa sovelluksissa kannettavasta elektroniikasta sähköajoneuvoihin. Suurin etu litiumioniakuilla verrattuna muihin akkuteknologioihin on niiden korkea energiatiheys. Korkea hinta ja turvallisuusriskit sähköisen tai mekaanisen väärinkäytön sattuessa ovat kuitenkin rajoittaneet litiumioniakkujen yleistymistä. Akun diagnostiikalla on keskeinen rooli litiumioniakkujen turvallisessa ja tehokkaassa käytössä. Kattavalla akun tilan seurannalla ikääntymisestä aiheutuvat prosessit akkukennossa voidaan havaita, ja käyttää akkua turvallisesti ja tehokkaasti.
Tässä diplomityössä esitetään katsaus kirjallisuudessa esiintyviin litiumioniakkujen diagnostiikkamenetelmiin. Näihin kuuluu muun muassa menetelmiä akun latausasteen (SOC), akun kunnon (SOH) ja jäljellä olevan käyttöiän arvioimiseksi.
Kaksi diagnostiikkamenetelmää toteutettiin ja testattiin tässä työssä: akun sisäisen lämpötilan arviointi impedanssispektroskopian (EIS) avulla ja akun kunnon (SOH) arviointi hyödyntäen differentiaalianalyysiä ja tukivektoriregressiota (SVR). Testauksessa hyödynnettiin kokeellista dataa litiumrautafosfaattikennoilta (LFP). Akkukennon EIS-mittaustuloksissa havaittiin selvä muutos kennon lämpötilan funktiona ja akun sisäisen lämpötilan arviointimenetelmän toimintaperiaate vahvistettiin. SVR-menetelmä osoittautui tarkaksi ja robustiksi, joskin sopivien parametrien valinnan suhteen herkäksi, menetelmäksi sileän käyrän sovittamiseksi mittausdataan. Differentiaalianalyysillä muodostetussa kapasiteetin differentiaalikäyrässä havaittiin kaksi selvää piikkiä, mikä vastasi tuloksia kirjallisuudessa. Lukuun ottamatta kennon ikääntymisen alkuvaihetta, piikit pienenivät kennon kapasiteetin laskiessa. Tätä korrelaatiota voidaan hyödyntää akun kunnon arvioinnissa, mutta lisätutkimukset ovat tarpeen menetelmän tarkkuuden ja luotettavuuden arvioimiseksi
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
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
Storage system dimensioning and design tool - D6.1 INVADE H2020
No full textThis document is INVADE project deliverable D6.1 Storage system dimensioning and design tool. This report presents background information, guidelines, and tools for dimensioning and design of energy storage systems for smart grids in general and for INVADE pilots in particular
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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