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1681 - 1690 / 2000
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1681.
Detoxified spent pot lining from aluminum production as (alumino-)silicate source for composite cement and autoclaved aerated concrete
Arne Peys, Mateja Košir, Ruben Snellings, Ana Mladenovič, Liesbeth Horckmans, 2021, original scientific article

Abstract: New sources of supplementary cementitious materials (SCMs) are needed to meet the future demand. A potential new source of SCM is spent pot lining, a residue from aluminum production. The present work showed that the refined aluminosilicate part of spent pot lining (SPL) has a moderate chemical reactivity in a cementitious system measured in the R3 calorimetry test, comparable to commercially used coal fly ash. The reaction of SPL led to the consumption of Ca(OH)2 in a cement paste beyond 7 days after mixing. At 28 and 90 days a significant contribution to strength development was therefore observed, reaching a relative strength, which is similar to composite cements with coal fly ash. At early age a retardation of the cement hydration is caused by the SPL, which should most likely be associated with the presence of trace amounts of NH3. The spent pot lining is also investigated as silica source for autoclaved aerated concrete blocks. The replacement of quartz by spent pot lining did not show an adverse effect on the strength-density relation of the lightweight blocks up to 50 wt% quartz substitution. Overall, spent pot lining can be used in small replacement volumes (30 wt%) as SCM or as replacement of quartz (50 wt%) in autoclaved aerated concrete blocks.
Keywords: spent pot lining, construction materials, recycling, autoclaved aerated conctrte, supplementary cementitious material
Published in DiRROS: 04.12.2023; Views: 292; Downloads: 104
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1682.
The importance of educating younger generations about raw materials and their uses in our daily life
Kim Mezga, Petra Vrhovnik, Janja Žmavc, Lidia Gullon, 2021, original scientific article

Abstract: Raw materials are of great importance for humankind as they enable the development of technology, drive industry and economy, and overall the lifestyle we know today. The paper is addressing the topic of interactive learning about the mineral raw materials, i.e. metals and non-metals. Due to population growth and consequently in-creased global demand for raw materials, there is a need to educate younger generations about the raw materials and their properties and origin, so they would know from an early age where the mineral products they use come from and how purchase decisions affect the social environments of people who live in countries with resources exploitation.Todayʼs trends in mining are oriented towards more sustainable exploitation and management, taking into account the economic, social and environmental aspects. An example of such is exploitation of secondary raw materials from tail-ings and heaps. But in some countries, mining is stuck in the past, using obsolete technologies causing increased pol-lution and strongly present linear economy approaches of take-use-dispose attitudes or even unethical approaches, such as children being exploited as a cheap workforce, people being abducted, tortured and even killed over minerals (min-erals being exploited in such way are called blood or conflict minerals). Further, due to the potential negative impacts on health and safety, due to the emissions in air, water and surface disturbance, the public perception of mining is still perceived as negative in most cases. School curriculums most often lack description of current situations in the global mining. Therefore, within the EIT RawMaterials BRIEFCASE and 3D BRIEFCASE projects the project partners provide the comprehensive view of the issues of todayʼs mining and use of raw materials. The paper presents the description of both projects and the non-conventional teaching methods - the hands-on and digital tools for pupils and teachers, i.e. the briefcases, the "Briefcase of mineral applications" game, workshops and the supporting materials. The main objective of projects is to raise the pupils awareness about the utility and indispensability of minerals and mining and the consequences of their uses and production systems, which would increasein the long term the awareness about the social and environmental consequences of raw material production.
Keywords: raw materials, mining, pupils and students, non-conventional teaching tools, BRIEFCASE, 3D BRIEFCASE, curricular planning, EIT RawMaterials
Published in DiRROS: 04.12.2023; Views: 334; Downloads: 155
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1683.
Določitev karakterističnih notranjih statičnih količin cestnih mostov iz podatkov tehtanja vozil med vožnjo
Aleš Žnidarič, Goran Turk, Maja Kreslin, 2022, original scientific article

Abstract: Prispevek obravnava določitev notranjih statičnih količin cestnih mostov iz podatkov tehtanj vozil med vožnjo (meritev WIM, ang. weigh-in-motion), ki edina zagotovijo celovito in nepristransko sliko o tovornem prometu na merjenem cestnem odseku. Tovrstni podatki so ključni za določitev realnih učinkov prometnih obtežb, s katerimi dokazujemo zadostno varnost mostov, tudi starih in poškodovanih. Takšne mostove bi bilo treba ob upoštevanju obtežnih shem iz sodobnih pravilnikov za mostove pogo- sto zapreti ali jim omejiti prometno obtežbo. Predstavljene so metode, s katerimi iz podatkov WIM izračunamo karakteristične vrednosti notranjih statičnih količin. Posebej smo analizirali metodo konvolucije in rezultate primerjali z rezultati ekstrapolacije ekstremnih vrednosti, najbolj pogostega postopka za napovedovanje maksimalnih pričakovanih vplivov prometa v izbranem obdobju, ter rezultati obsežnih numeričnih simulacij. Veliko pozornost smo namenili izbiri vhodnih parametrov ter načinu od- čitavanja karakterističnih vrednosti, ki bistveno vplivajo na rezultate ekstrapolacij in simulacij. Rezultati kažejo, da daje metoda konvolucije, ki je računsko neprimerno manj zahtevna od ostalih uporabljanih metod, primerljive rezultate. Sočasno so le-ti manj občutljivi za subjektivno izbiro uporabljenih parametrov. Bistveni zaključek analize je tudi, da za zanesljiv račun karakte- rističnih notranjih statičnih količin mostov zaradi prometa potrebujemo s sistemom WIM izmerjene osne pritiske in medosne razdalje vsaj 100.000 tovornih vozil.
Keywords: most, tehtanje vozil med vožnjo, notranje statične količine, konvolucija, simulacija, WIM, B-WIM
Published in DiRROS: 04.12.2023; Views: 325; Downloads: 123
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1684.
Modeliranje izgube uporabnosti in ocena navidezne starosti asfaltnih vozišč na osnovi vizualne ocene stanja
Primož Pavšič, 2022, original scientific article

Abstract: Pod vplivi prometnih obremenitev in okoljskih vplivov se kakovost vozišč stalno slabša. Z uporabo modificiranega švicarskega indeksa MSI lahko ocenimo in spremljajmo staranje vozišča, sposobnost zagotavljanja njegove funkcije pa lahko opredelimo z izgubo uporabnosti vozišča. Prispevek podaja predlog nove modelne funkcije za opredelitev staranja vozišča oziroma njegove izgube uporabnosti na osnovi vizualne ocene stanja vozišča (MSI) in določitev njegove navidezne starosti glede na predlagani model staranja vozišč.
Keywords: vozišče, ocena stanja, MSI, model
Published in DiRROS: 04.12.2023; Views: 260; Downloads: 149
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1685.
Računski model za opis temperaturnega vpliva na meritve deformacij
Uroš Bohinc, 2022, original scientific article

Abstract: V prispevku je predstavljen izviren način za napoved odvisnosti izmerjenih deformacij od temperature okolice. Izhaja iz poenostavljenega fizikalnega modela, ki je umerjen s pomočjo niza obstoječih meritev, ki pokrivajo časovni razpon enega leta. Spremljanje konstrukcijskega stanja zvonika stolnice sv. Anastazije v Zadru je bilo opravljeno z namenom, da bi zanesljivo določili morebitne dolgotrajne trende obnašanja in tako omogočili pravočasno ukrepanje. Za uspešno določitev dolgotrajnih trendov je ključna ločitev temperaturnega vpliva na meritve. Rezultati kažejo, da je mogoče na predstavljeni način dokaj dobro izločiti temperaturni vpliv na meritve in tako izboljšati zaznavo morebitnih dolgotrajnih trendov.
Keywords: meritve deformacij, modeliranje temperaturnega vpliva, spremljanje konstrukcijskega stanja
Published in DiRROS: 04.12.2023; Views: 279; Downloads: 137
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1686.
1687.
Vacuum biopsy of the breast : experience of St-Jan hospital in Brugge
Luc Steyaert, Filip van Kerkhove, Jan Caselmann, 2004, published scientific conference contribution

Abstract: Background. Mammotome is a percutaneous biopsy technique with a large needle, assisted by vacuum aspiration. The single insertion technique allows to collect multiple large tissue samples, which gives a more reliable histological result. The technique can be used under stereotactic, MRl or ultrasound guidance. The technique is used under local anesthesia, on an outpatient basis. Conclusions. Altough it is essentially a diagnostic technique, it has a therapeutic potential in some cases. Recently, the technique has been FDA approved for the removal of benign nodular lesions. Worldwide, over 2 million procedures have already been performed. It has the potential to replace surgical open biopsy, with a similar accuracy and at a lower cost, and it is less invasive.
Published in DiRROS: 01.12.2023; Views: 218; Downloads: 55
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1688.
1689.
The contribution of new US technologies to US differential diagnosis of nonpalpable lesions
Giorgio Rizzatto, Roberta Chersevani, Martina Locatelli, 2004, published scientific conference contribution

Abstract: Background. Gray-scale ultrasound (US) patterns are still the best indicators of the risk of malignancy and correlation with mammography and guidance to bioptical procedures are still the gold standard in breast diagnosis. But recent technological advancements in ultrasound offer new diagnostic capabilities that integrate conventional US imaging: 3D, CAD, perfusion imaging and elastography. Conclusions. The US technologies allow to differentiate and grade the vascularity of breast lesions (both with conventional technologies and with contrast enhancers) and to evaluate the elastic properties of the normal and pathologic tissues (elastography). Both these technologies are on the way of becoming commer cially available on medium and high-end US instruments. But they must still be considered as research tools because their diagnostic efficacy requires more widely clinicaltesting.
Published in DiRROS: 01.12.2023; Views: 186; Downloads: 57
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1690.
3D/4D breast ultrasound : diagnostic and intervention
Christian Weismann, 2004, published scientific conference contribution

Abstract: Background. Three-dimensional (3D) and four dimensional(4D) mammasonography isthe most recent development in breast ultrasound imaging providing additional aspects to conventional two-dimensional (2D) sonography. Conclusions. The new technique of mammasonography enable completely new superior diagnostic information such as the ability to study a breast mass andthe surrounding tissue in 3 orthogonal planes, or to obtain new informationabout the mean blood flow intensity or vascularisation of breast lesions by evaluation of the 3D colour histogram. 4D ultrasound offers almost real time 3D rendered image information and is taken as a basis of multidimensional imaging of the breast.
Published in DiRROS: 01.12.2023; Views: 205; Downloads: 48
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