Strut and tie method for design of plane reinforced concrete elements

The 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 Role of Cellulose Based Separator in Lithium Sulfur Batteries

International audienceIn this work, abundant and environmentally friendly nano-fibrillated (NFC) cellulose is used for fabrication of porous separator membranes according to the procedure adopted from papermaking industry. As-prepared NFC separators were characterized in terms of thickness, porosity, wettability, electrochemical stability and electrochemical performance in lithium-sulfur and Li-symmetrical pouch cells and compared to a commercial Celgard 2320 separator membrane. Results demonstrated that morphology and electrochemical performance of NFC separator outperforms the conventional polyolefin separator. Due to exceptional interplay between lithium metal and cellulose, this research provides a self-standing NFC separator that can be used besides the lithium-sulfur also in other lithium metal battery configurations

Strut and tie method for design of plane reinforced concrete elements

V 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

Modified cellulose separators in lithium-sulphur batteries

Litij 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

The impact of the Covid-19 pandemic on gambling tourism in the Urban Municipality of Nova Gorica

Diplomsko 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