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Matej Matjašec, 30, bachelor thesis/paper

Abstract: V diplomskem delu bomo obravnavali sisteme za upravljanje spletnih vsebin, razlike sistemov CMS sistemov pa se vidijo večinoma v njihovih funkcionalnostih. Omejili se bomo na sledeče sisteme za upravljanje vsebin Joomla, WordPress, Drupal, Concrete, Modx, Xoops nad katerimi bomo izvedli kriterije in primerjanje funkcionalnosti sistemov. Uporabili bomo odločitveni program Dexi s katerim bomo določili najbolj optimalen sistem za upravljanje vsebin za določeno skupino uporabnikov. Izvedli bomo tudi anketni vprašalnik zaprtega tipa, s katerim bomo analizirali priljubljenost CMS sistemov študentov FERI.
Keywords: Sistemi za upravljanje vsebin, Joomla, WordPress, Drupal, Concrete, Modx, Xoops, analiza, funkcionalnosti, primerjava.
Published: 28.10.2011; Views: 2335; Downloads: 290
.pdf Full text (2,64 MB)

Hardening of concrete with a planned delayed ettringite formation
Samo Lubej, Andrej Ivanič, Milan Radosavljević, 2009, published scientific conference contribution

Abstract: Delayed ettringite formation (DEF) in cementitious materials is widely considered as a harmful chemical reaction that causes extensive damages in hardened concrete. However, preventative measures and possible improvements in general are not extensively studied and require further attention. In this study was presented an investigation into a type of controlled DEF in places of finely dispersed crystallisation nuclei and provide evidence that the process may improve compressive strength of cementitious materials. The Alkali-Silica Reaction (ASR) in hydrated concrete was achieved with the addition of fly ash and was further accelerated with the Dugganćs test. Achieved strengths and monitoring of microstructure development conducted with electronic microscopy revealed that growth of ettringite crystals in the nuclei led to harmless internal compressive stresses, expansion of hydrated concrete and overall strengthening of the concrete matrix.
Keywords: delayed ettringite formation, concrete, hardening
Published: 31.05.2012; Views: 952; Downloads: 20
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Tungsten - tungsten trioxide electrodes for the long-term monitoring of corrosion processes in highly alkaline media and concrete-based materials
Mitja Kolar, Aleš Doliška, Franc Švegl, Kurt Kalcher, 2010, original scientific article

Abstract: The determination of pH in highly alkaline solutions and concrete materials is extremely important for monitoring or predicting the corrosion processes of reinforced concrete structures and to follow the hydration process of Portland cement, fly-ash, micro silica and other materials used in concrete manufacturing. The corrosion of reinforced concrete structures and the hydration of pozzolanic materials are long-term processes, which means, that appropriate durable, and resilient pH electrodes are needed, for direct implantation regarding solid concrete bodies. The purpose of this work was to characterise the potentiometric and surface properties of tungsten electrodes after exposure to extreme alkaline solutions. The tungsten wire surface was activated at 800 °C for 30 min within an oxygen flow. The formation of homogenous and compact multiple layers of $WO_3$ crystals was observed using X-ray diffraction and scanning electron microscopy. X-ray diffraction of thosetungsten electrodes exposed to saturated calcium hydroxide solution or the pore-water of cement-based materials during 10 months, indicated partly dissolved $WO_3$. Two new compounds appeared on the electrodes surfaces; pure tungsten and $CaWO_4$. The presence of tungsten was affecting any potentiometric response in acidic pH region (2-5) but in pH 5-12 region the response still remained linear with a slope of 42 2 mV/pH unit. The $W/WO_3$ electrode was suitable for the long-term monitoring of corrosion processes in concrete-basedmaterials according to the pH changes as it has stable and repeatable responses to alkaline solutions (pH > 12). All the tested interferring ions had no significant influence on electrode potential. The $W/WO_3$ electrode is simple, robust, inexpensive, and temperature resistant and can be applied in potentiometric titrations as well as in batch and flow-injection analysis. The prepared electrode is a highly promising pH sensor for the monitoring of pH changes in highly alkaline capillary water of concrete.
Keywords: potentiometry, pH, tungsten - tungsten trioxide, pore water, concrete, flow-injection analysis
Published: 31.05.2012; Views: 1594; Downloads: 49
.pdf Full text (1,67 MB)
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Utilization of bottom ash from the incineration of separated wastes as a cement substitute
Filip Kokalj, Niko Samec, Bernardka Jurič, 2005, original scientific article

Abstract: Waste incineration is still an essential technology in the concept of integrated waste management. Most of the combustion residues are incinerator bottom ash. It has been discovered that incinerator bottom ash from the incineration of separated waste in the primary chamber of the modular two-stage incinerator mainly consists of metal oxides, especially SiO2 and CaO, in proportions that are quite similar to those in cement and so the feasibility of its application as a substitute for cement in concrete was investigated. It was found that after 28 days, the flexural and compressive strengths of the binder using bottom ash were practically comparable with those of a pure cement mixture. The results show that it is reasonable to use a binder containing incinerator bottom ash for applications in which an early-stage lower strength of concrete element is acceptable.
Keywords: waste management, solid municipal waste, separated wastes incineration, bottom ash, cement, concrete
Published: 01.06.2012; Views: 1295; Downloads: 83
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Tadeja Leskovar, 2014, master's thesis

Abstract: This Master’s thesis topic are Enterprise Resource Planning (ERP) solutions in general with emphasis on systems appropriate for small and medium sized enterprises and industry specific solutions. The chosen industry and case study of the present thesis are manufacturing and construction; specifically the industry of ready-mixed concrete manufacturing. An ERP is a company-wide system that replaces many previously scattered and standalone systems of individual departments and offices. After the (successful) implementation it integrates all functions into a single, automated system that runs on a single database. This thesis strives to present different stages of ERP acquiring, from decision-making, through implementation and use. Because the empirical part contains a presentation of an actual business and their requirements, we focus in the particular conditions and issues related to the size and industry of the given company, Beton – Betonski izdelki Kuhar Dušan, s.p throughout the thesis. Additionally, part of the thesis is also presentation and potential beneficial role of one of the leading organizations in the area of project management – Project Management Institute. The outcome of our research is realization that ERP solutions are a crucial aspect of modern companies if they wish to be competitive on the market, have the ability to grow, and continuously maintain the existing pool of costumers. However, before the right ERP solution can be selected, a careful decision-making needs to be undertaken and implementation has to be thoroughly planned. There are many tools and guides that can be used with such demanding project. Project Management Institute, which will be presented in this work, offers many advices on the topic in question.
Keywords: ERP solutions, SMEs, ready-mixed concrete, Project Management Institute
Published: 13.10.2014; Views: 1120; Downloads: 122
.pdf Full text (2,38 MB)

Influence of delayed ettringite formation on the mechanical properties of aerated concrete
Samo Lubej, Andrej Ivanič, Rebeka Rudolf, Ivan Anžel, 2012, original scientific article

Abstract: Delayed ettringite formation (DEF) is a chemical reaction with proven damaging effects on the mechanical properties of a hydrated concrete. Ettringite crystals can cause cracks and their widening due to the pressure on the crack walls caused by a positive volume difference in the reaction. Concrete may show improvements in strength at early stages, but a further growth of the cracks causes widening and spreading of these cracks through the concrete structure. In a hydrated concrete, crystals of ettringite can also cause a disintegration of the concrete. In this paper we investigate the potential to utilise a positive volume difference in DEF in order to improve the mechanical properties of a hydrated fine-grained concrete. Finely dispersed crystallization nuclei, achieved by adding an air-entraining agent (AEA) and a short vibration of specimens, is presented as the main prerequisite for such improvements. The control of the expansion and mechanical properties were performed on the concrete samples with and without AEA by inducing DEF. For a microstructure examination of the fine-grained concrete an optical microscope and a scanning electron microscope were used. We found that controlled DEF, which is guaranteed by adding AEA and with the formation of the uniformly dispersed air bubbles, which are the crystallization sites for ettringite crystals, improves the mechanical properties. The specimens with induced DEF were measured and found to have a 6% increase in the compressive strength.
Keywords: ettringite, concrete, aerated concrete, microstructure, mechanical properties
Published: 10.07.2015; Views: 593; Downloads: 56
.pdf Full text (426,54 KB)
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Potential reduction of concrete deterioration through controlled DEF in hydrated concrete
Samo Lubej, Milan Radosavljević, 2013, original scientific article

Abstract: Delayed ettringite formation (DEF) is a chemical reaction with proven damaging effects on hydrated concrete. Ettringite crystals can cause cracks and their widening due to pressure on cracked walls caused by the positive volume difference in the reaction. Concrete may show improvements in strength at early ages but further growth of cracks causes widening and spreading through the concrete structure. In this study, finely dispersed crystallization nuclei achieved by adding air-entraining agent (AEA) and short vibration of specimens is presented as the main prerequisite for reducing DEF-induced deterioration of hydrated concrete. The study presents the method and mechanism for obtaining the required nucleation. Controlling long-term DEF by providing AEA-induced crystallisation nuclei, prevented excessive and rapid initial strength improvements, and resulted in a slight increase of compressive strength of fine grained concrete with only marginally lower density.
Keywords: delayed ettringite formation, aerated concrete, strength improvement
Published: 10.07.2015; Views: 563; Downloads: 20
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Methods for control of seepage in RCC dams with wathertight and drainage measures
Yueming Zhu, Stephan Semprich, Erich Bauer, Cuiping Yuan, Dongmei Sun, 2006, original scientific article

Abstract: The technologies for construction of roller-compacted concrete (RCC) dams have been considerably developed during recent years in China. At the time being, they have been successfully applied to the constructions of even extreme-high gravity dams and medium to high arch dams. There are a few of hundreds of RCC dams (RCCD) under design and/or construction in China. One of the main concerned technical problems according to the construction is about the understanding of the property of seepage in RCCDs and the relevant theory and methods for the control of the seepage. In order to overcome the problem, the senior author has been engaged in a wide study on the property and methods for control of seepage in RCCDs for more than 10 years. The property of seepage, measures for watertightness and drainage, optimal design and construction schemes for control of seepage in the dams have been essentially understood either in theory and practice. The results have been applied for the construction and the backanalysis of several dams. The paper describes the research findings in detail with respect to the theoretical fundament and their application for a high RCC gravity dam.
Keywords: gravity dam, Roller-compacted concrete, RCC, seepage, anisotropic permeability, drainage
Published: 17.05.2018; Views: 305; Downloads: 20
.pdf Full text (209,12 KB)
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New Architecture of The Berane Airport
Ivan Pićurić, 2018, master's thesis

Abstract: This Master's Thesis explores the concept of the New Berane Airport that will serve as a turning point for improving the winter tourism offer of Montenegro and the region, thereby attracting a greater number of tourists to the country. The new facility must follow the guidelines of modern architecture, modern design, and the surrounding mountain landscapes, which represents an additional challenge in terms of construction and design. The main aim is to create an efficient structure, a new regional aviation centre, with well-designed transport links that will meet the needs of a large number of passengers and visitors from the region and the rest of the world. The visual aspects of the structure must be in line with the dominant type of architecture in the municipality of Berane, which is why the use of local materials and traditional elements has been foreseen. The new urban plan will follow the existing plan, although its capacity and content will be expanded in accordance with the former plans for the airport. In the planning phase, appropriate use of airport and traffic manuals is essential.
Keywords: airport, architecture, concrete, shell roof, glass facade, tourism, transport, parametric design, regional centre, Berane
Published: 15.06.2018; Views: 423; Downloads: 172
.pdf Full text (38,54 MB)

A fundamental study of the performance of X-section cast-in-place concrete single piles
Yu Wang, Yaru Lv, Dongdong Zhang, Jieying Zhou, 2016, original scientific article

Abstract: X-section cast-in-place concrete (XCC) piles are used because they have a higher bearing capacity than circularsection cast-in-place concrete (CCC) piles of the same cross-sectional area. Although the bearing capacity of XCC piles has been studied, the performance of XCC single piles, especially for the stress-transfer mechanism dependent on the geometrical effects, is still not fully understood. This paper reports two comparative field static load tests on an XCC and a CCC single pile of the same cross-sectional area. In addition, corresponding threedimensional numerical back-analyses are performed to provide a fundamental understanding. The measured and computed results reveal that the XCC single pile has an approximately 25% higher ultimate bearing capacity than the CCC single pile. This is because the XCC single pile has an approximately 20% larger total side resistance, which is caused by a 60% larger pile perimeter and a slightly smaller unit side resistance. Lateral soil arching effects are developed, causing a non-uniform effective normal stress and a shear stress across the circumference of the XCC single pile. It is suggested that XCC single piles have a higher efficiency in terms of material saving compared with CCC single piles.
Keywords: X-section cast-in-place concrete pile, field static load test, three-dimensional numerical back-analysis, stresstransfer mechanism, side resistance, soil arching
Published: 15.06.2018; Views: 460; Downloads: 23
.pdf Full text (485,57 KB)
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