1,720,961 research outputs found
Protective coating for stable cycling of Li-metal batteries based on cellulose and single-ion conducting polymer
Get PDFThe thermodynamically unstable interface between metallic lithium and electrolyte poses a major problem for the massive commercialization of Li-metal batteries. In this study, we propose the use of a multicomponent protective coating based on cellulose modified with dimethylthexylsilyl group (TDMSC), single-ion conducting polymer P(LiMTFSI), and LiNO (TDMSC-P(LiMTFSI)-LiNO, namely PTL). The coating shows its positive effect by increasing the Coulombic efficiency in Li || Cu cells from 95.9 and 98.6% for bare Li, to >99.3% for Li coated (Li@PTL), with 1 M LiFSI in FEC:DEC and 1 M LiFSI in DME electrolyte, respectively. Symmetrical Li || Li PTL-coated cells exhibit a much more prolonged and stable cycling with a slower increase in overpotential compared to bare Li cells. Li@PTL anodes enable improved cycling of Li@PTL/LFP cells compared to noncoated cells in liquid electrolytes. In this respect, inhibition of high surface area lithium growth is confirmed through postcycling scanning electron microscopy. Remarkably, dendrite-free galvanostatic cycling is demonstrated in laboratory-scale solid-state battery cells assembled with LFP composite cathode (catholyte configuration with PEO + LiTFSI as ionically conducting binder) and a cross-linked PEO-based solid polymer electrolyte. The PTL protective coating enables improved stability of Li metal batteries in combination with smooth transport of Li at the electrode−electrolyte interface and homogeneous lithium coating, highlighting its promising prospects in enhancing the performance and safety of lithium metal batteries by properly tuning the synergy between the coating components
Strut and tie method for design of plane reinforced concrete elements
Get PDFThe thesis presents the process of designing reinforced concrete structural elements by the strut and tie\ud
method. The standard SIST EN 1992-1-1:2005 allows the implementation of this known, but rarely\ud
used dimensioning method. It can be used for dimensioning of both deep beam construction elements\ud
and certain sections of linear constructions where plane stress state is produced as a result of various\ud
reasons and the beam theory can no longer accurately describe the actual situation. The thesis provides\ud
insight into the basic idea of the method. The effectiveness of dimensioning by means of this method\ud
strongly depends on the predefined position of ties and struts. To this end, a large portion of the thesis\ud
deals with determining adequate alternate trusses for different construction elements and details, such\ud
as: deep beams, junctions of two linear construction elements, corbels, dapped beams, deep beams\ud
with openings, etc. The research was based on the existing literature containing established models,\ud
and topology optimisation. The latter was conducted by means of two open source computer\ud
programmes, i.e. ForcePad 2 and TopoStruct. The thesis also presents the results of topology\ud
optimisation for different examples. Alternate trusses calculated using topology optimisation are\ud
compared to the models suggested in the literature. The last part of the thesis presents three numerical\ud
examples for different constructions to illustrate the method in question. The examples determine\ud
adequate alternate trusses; individual truss elements are dimensioned (ties, struts and nodes) and all\ud
controls implemented in line with the standard SIST EN 1992-1-1:2005
The impact of the Covid-19 pandemic on gambling tourism in the Urban Municipality of Nova Gorica
No full textDiplomsko delo opisuje vpliv pandemije covida-19 na igralniški turizem v Mestni občini Nova Gorica. Naloga vsebuje splošno predstavitev igralniškega turizma in opredelitev ključnih pojmov, povezanih z njim. Vključen je tudi opis preučevanega območja, tj. Mestne občine Nova Gorica, z vsemi njenimi glavnimi turističnimi znamenitostmi, ter pregled stanja turizma pred, med in po pandemiji na državni ravni. Jedro diplomskega dela vsebuje analizo statističnih podatkov o turističnem obisku Mestne občine Nova Gorica v obdobjih pred, med in po pandemiji, in sicer na bazi podatkov Statističnega urada Republike Slovenije, hkrati pa analiza zaobjema tudi vse glavne kazalnike poslovanja glavnega novogoriškega ponudnika na področju igralništva, podjetja Hit, skozi vsa tri našteta obdobja. Omenjena analiza odpira možnosti za nadaljnje preučevanje igralniškega turizma, saj se njegova priljubljenost po pandemiji spet veča.This Bachelor\u27s thesis describes the impact of the Covid-19 pandemic on gambling tourism in the Urban Municipality of Nova Gorica. The thesis provides a general introduction to gambling tourism and defines key related terms. It also includes a description of the study area, i.e. the Urban Municipality of Nova Gorica, with all its main tourist attractions, and an overview of the state of tourism before, during, and after the pandemic at the national level. The core of the thesis contains an analysis of statistical data on tourist arrivals in the Urban Municipality of Nova Gorica in the periods before, during, and after the pandemic, based on data from the Statistical Office of the Republic of Slovenia. The core also covers all the main performance indicators of the main gambling operator in Nova Gorica, Hit, throughout the three periods mentioned above. This analysis allows for further study of gambling tourism as its popularity is increasing again in the wake of the pandemic
Modified cellulose separators in lithium-sulphur batteries
Get PDFLitij žveplovi akumulatorji so eden najobetavnejših kandidatov za prevzem primata litij ionskim akumulatorjem na področju shranjevanja energije,saj jih odlikujejo številne zaželene lastnosti, kot so nizka cela aktivnih materialovin majhen vpliv na okolje. Poleg tega je njihova teoretična gostota energije veliko višja od komercialnih litij ionskih akumulatorjev, ki temeljijo na interkalacijskih materialih. Kljub tem prednostim množično uporabo Li-S akumulatorjev ovirajo številni izzivi, povezanis hitro izgubo kapacitete večinoma zaradi izgube aktivnega materiala in elektrokemijsko nestabilnega pasivnega sloja med kovinski litijem in različnimi vrstami elektrolitov. Celuloza je najbolj razširjen polimer na Zemlji in zaradi svojih dobrih mehanskih lastnosti, enostavne modifikacije ter biorazgradljivosti primeren kandidat za naslovitev problemov Li-S akumulatorjev, če se uporabi kot separacijski sloj med žveplovo katodo in anodo iz kovinskega litija. Primarna vloga separatorja v akumulatorskih celicah je preprečitev kontakta med anodo in katodo, s primerno modifikacijo in izdelavo pa je z njim mogoče vplivati tudi na procese v akumulatorski celici. Primerne lastnosti celuloze in zmožnost njenega vpliva na procese v akumulatorski celici so bile glavne smernice te doktorske disertacije.
V našem delu smo najprej iz nanofibrilirane celuloze (NFC) izdelali samostoječe NFC-separatorje in dokazali, da se izboljša delovanje Li-S akumulatorjev v primerjavi s komercialnimi separatorji. Z uporabo XPS-spektroskopije in SEM-FIB-mikroskopije smo pokazali, da NFC-separator še posebno dobro vpliva na kovinsko litijevo elektrodo.
Za naslovitev problema difuzije in migracije topnih polisulfidnih zvrsti iz žveplaste katode smo sintetizirali dva različna celulozna materiala: fluoro NFC in s polianilinom oplaščeno NFC ter jih implementirali v Li-S akumulator. Oba materiala sta imela pozitiven učinek na migracijo topnih polisulfidnih zvrsti po Li-S akumulatorski celici, nista pa v celoti odpravila problema hitre izgube kapacitete Li-S akumulatorjev.
Pozitivni vpliv NFC materialov na kovinsko litijevo elektrodo smo z izdelavo zaščitnih preverili slojev direktno na litijevi površini z uporabo trimetilsilil celuloze. Rezultati analiz so pokazali, da tanek zaščitni sloj na osnovi NFC uspešno zavre dendritsko rast litija, prepreči korozivne reakcije med kovinskim litijem in elektrolitom tertako stabilizira kovinsko litijevo elektrodo.Lithium sulphur batteries are one of the most promising candidates to take primacy of the lithium-ion batteries in the field of energy storage due to their desirable features, such as competitive cost of production and low environmental impact. In addition, their exceptional theoretical energy density is much higher than commercial Li-ion batteries based on intercalation materials. Despite of these advantages, the mass commercialization of Li-S batteries is still hampered by the many challenges associated with rapid loss of capacity, mainly due to the loss of active material and the electrochemically unstable passive layer between lithium metal and various types of electrolytes. Cellulose is the most abonded polymer material on the Earth and, due to its good mechanical properties, easy modification and biodegradability, is a suitable candidate for addressing Li-S battery problems and it can be used as separation layer between sulphur cathode and lithium metal anode. The primary role of the separator in the battery cell is to prevent contact between the anode and the cathode, with appropriate modification and fabricationit can also affect the processes in the battery cell. Appropriate cellulose properties and the ability to influence processes through separator has been the main focus of this doctoral dissertation.
In presented work, we first constructed self-standing separator membranes from nano-fibrillated cellulose (NFC) and proved that they improve the performance of Li-S batteries compared to commercial separator membranes. Using XPS spectroscopy and FIB-SEM microscopy, we showed that the separator membranes from NFC has, in particular, good effect on the lithium metal electrode.
To address the problem associated to the diffusion and migration of soluble polysulphides species from the sulphur cathode, two different NFC materials were synthesized: fluoro NFC and polyaniline coated NFC, and implemented in a Li-S battery. Both materials had a positive effect on the migration of soluble polysulphides species across the Li-S battery cell, but did not completely solved the problem of rapid capacity loss of Li-S batteries.
Positive effect of NFC materials on the metal lithium electrode was verified with implementation of protective layers based on cellulose directly on the lithium metal surface using trimethylsilyl cellulose. The results of the analyses showed that a thin NFC based protective layer successfully inhibits dendritic growth of lithium, preventing corrosive reaction between the lithium metal and the electrolyte, thus stabilizing the lithium metal electrode
Strut and tie method for design of plane reinforced concrete elements
Get PDFV diplomskem delu je predstavljen postopek projektiranja armiranobetonskih konstrukcijskih
elementov z metodo vezi in razpor. To je sicer znana, vendar ne zelo razširjena metoda za
dimenzioniranje, ki jo dopušča tudi standard SIST EN 1992-1-1:2005. Uporablja se lahko za
dimenzioniranje stenastih konstrukcijskih elementov ter za dimenzioniranje takšnih odsekov linijskih
konstrukcij, kjer se zaradi različnih razlogov pojavi ravninsko napetostno stanje in teorija nosilcev ne
more več primerno opisati dejanskega stanja. V nalogi je opisana osnovna ideja metode. Kako
učinkovito bo dimenzioniranje z omenjeno metodo, je v veliki meri odvisno od predpostavljenega
poteka vezi in razpor. Zato se velik del naloge ukvarja z določevanjem ustreznega nadomestnega
paličja za različne konstrukcijske elemente in konstrukcijske detajle, kot so: stenasti nosilci, stik dveh
linijskih konstrukcijskih elementov, kratke konzole, nosilci z vozliščem z reducirano višino, visoki
nosilci z odprtinami in podobno. Pri tem smo si pomagali z napotki iz literature, že uveljavljenimi
tipičnimi modeli, ki jih je moč najti v literaturi ter s topološko optimizacijo. Slednja je v nalogi
izvedena z enostavnima prosto dostopnima računalniškima programoma ForcePad 2 in TopoStruct.
Prikazani so rezultati topološke optimizacije za različne primere. Nadomestna paličja, ki smo jih dobili
s topološko optimizacijo, so primerjana z modeli, ki jih je moč najti v literaturi. Na koncu diplomske
naloge so prikazani trije računski primeri za različne konstrukcije, ki so rešeni z opisano metodo.
Določeno je primerno nadomestno paličje, nato pa so dimenzionirani posamezni elementi paličja
(vezi, razpore in vozlišča), pri čemer so izvedene vse potrebne kontrole v skladu s standardom SIST
EN 1992-1-1:2005.
Pavlin, N. 2012. Metoda vezi in razpor za projektiranje armiranobetonskih stenastih elementov. III
Dipl. nal.- UNI. Ljubljana, UL, FGG, Odd. za gradbeništvo, Konstrukcijska smer.The thesis presents the process of designing reinforced concrete structural elements by the strut and tie
method. The standard SIST EN 1992-1-1:2005 allows the implementation of this known, but rarely
used dimensioning method. It can be used for dimensioning of both deep beam construction elements
and certain sections of linear constructions where plane stress state is produced as a result of various
reasons and the beam theory can no longer accurately describe the actual situation. The thesis provides
insight into the basic idea of the method. The effectiveness of dimensioning by means of this method
strongly depends on the predefined position of ties and struts. To this end, a large portion of the thesis
deals with determining adequate alternate trusses for different construction elements and details, such
as: deep beams, junctions of two linear construction elements, corbels, dapped beams, deep beams
with openings, etc. The research was based on the existing literature containing established models,
and topology optimisation. The latter was conducted by means of two open source computer
programmes, i.e. ForcePad 2 and TopoStruct. The thesis also presents the results of topology
optimisation for different examples. Alternate trusses calculated using topology optimisation are
compared to the models suggested in the literature. The last part of the thesis presents three numerical
examples for different constructions to illustrate the method in question. The examples determine
adequate alternate trussesindividual truss elements are dimensioned (ties, struts and nodes) and all
controls implemented in line with the standard SIST EN 1992-1-1:2005
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
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
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