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1.
GNSS monitoring of geologically demanding areas
Boštjan Kovačič, Boško Pribičević, Rok Kamnik, 2016, original scientific article

Abstract: Displacement research using the three-dimensional global navigation satellite system (GNSS) as part of geodetic monitoring is becoming the key investigation for establishing a cause-and-effect relationships model between external natural factors, on the one hand, and the criteria that describes the level of functionality and safety of the observed natural or artificial object, on the other, in cases of motion of an object in space and time. The main objective of the deformation analysis is to confirm the stabilities of the reference points of a geodetic network, which are used to determine the movements of the control points that are stabilized on the observed objects. The assumption about the stabilities of certain reference points must be based on reasonable grounds, underpinned by measurements and proven by numerical methods. This is one part of the results of the deformation analysis when determining the extent of the movements and deformations. To do this a transformation is used in which a comparison is made between the coordinates of the points for two separate epochs. On the basis of the estimated transformation parameters, possible movements can be concluded within the reference points, i.e., on whether the datum parameters have changed. After confirming the stability of the geodetic network the coordinate differences of identical points measured within the different time windows can be determined as displacements and/or deformations of an object. In this paper one viaduct was assessed through geology and tectonic activities and also a load test of the viaduct was performed. The viaduct is in a quite active region, but the load test showed that the bridge response to the load is as expected.
Keywords: geodesy, geotehnics, monitoring, GNSS measurements, geology, deformation analysis, geodetic network
Published: 18.06.2018; Views: 678; Downloads: 42
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2.
Measurement and interpretation of the small strain stifness of Boštanj silty sand
Gregor Vilhar, Vojkan Jovičić, 2009, original scientific article

Abstract: This paper presents measurements, and an interpretation of these measurements, based on the use of bender-element probes for Boštanj silty sand. The samples were prepared at different initial void ratios and isotropically compressed up to 5 MPa. The bender-element technique was used to determine the dynamic shear modulus ($G_0$) of the soils at very small strains. The multiple bender-element probes were shot at different excitation frequencies in order to increase the reliability of the measurements. The $G_0$ stiffness was determined by using three different techniques: a) the first-time arrival, b) the phase-change method and c) the cross-correlation method. The systematic differences observed between the $G_0$ values, calculated using the three techniques, are discussed. The variation of $G_0$ in the log$G_0$ - log$p'$ plane was evaluated for the Boštanj silty sand and compared with other sands.
Keywords: silty sand, triaxial testing, small strain stiffness, bender elements, time-domain and frequency-domain, measurements
Published: 06.06.2018; Views: 531; Downloads: 40
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3.
Displacements in the exploratory tunnel ahead of the excavation face of Šentvid tunnel
Jure Klopčič, Janko Logar, Tomaž Ambrožič, Andrej Štimulak, Aleš Marjetič, Sonja Bogatin, Bojan Majes, 2006, original scientific article

Abstract: Fitting the displacement function to the measured displacements enables the assessment of the stabilization process of the observed cross section and the determination of its normal behaviour. The displacement function consists of three parts. Whilst the third part has been successfully applied for several times and thus proven to be very well defined, the first two parts were defined only on the basis of numerical simulations. To overcome this deficiency and to obtain the necessary coefficients of the pre-face part of the displacement function, the 3D displacement measurements ahead of the face due to tunneling should be performed. Such measurements were performed in the exploratory tunnel of the Šentvid tunnel during the excavation of the main tunnel. This paper presents the Šentvid tunnel project, the method of the 3D displacement measurements, the results of these measurements and their interpretation according to the geological structure of the site with an emphasis on items important for the coefficients of the displacement function.
Keywords: tunnels, exploratory tunnel, geodetic displacement measurements, pre-face displacements
Published: 17.05.2018; Views: 786; Downloads: 50
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4.
The assesment of pile shaft resistance based on axial strain measurements during the loading test
Andrej Štrukelj, Stanislav Škrabl, Ksenija Štern, Janko Logar, 2005, original scientific article

Abstract: Near Maribor, a new bridge over the Drava river is being under construction. Before the main works actually started, static and dynamic loading tests of piles were performed. The goal of the static loading test was to determine the bearing capacitiy of the test pile. It was also interesting to determine the share of the axial load distributed on the shaft and pile toe. In order to measure the distribution of the axial force along the pile, a specially made steel canal was built in the pile before concreting. Inside this canal the strain gauges were distributed evenly at the distance of one meter. The strains were measured for each loading phase in all measuring points. The distribution of the axial force was assessed from the obtained results and based on the distribution of the axial force the shaft resistance could be determined. The unexpectedly high bearing capacity of the pile shaft made the obtained results highly interesting. In this paper, measuring methods and measuring results are discussed. Behaviour of the pile and the soil during the loading test were also modelled by axial symmetric and three dimensional models. The calculated and measured results show a very good agreement.
Keywords: civil engineering, bridges, soil mechanics, pile shaft resistance, loading test, strain measurements, elastoplastic soil modelling, finite element method
Published: 16.05.2018; Views: 716; Downloads: 39
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5.
Synthesis, crystal structure and magnetic properties of a new hydroxylammonium fluoroferrate
Brina Dojer, Matjaž Kristl, Zvonko Jagličić, Amalija Golobič, Marta Kasunič, Mihael Drofenik, 2012, original scientific article

Abstract: This paper reports on the synthesis of a new hydroxylammonium fluoroferrate, with the formula $(NH_3OH)_3FeF_6$, obtained after dissolving iron powder in hydrofluoric acid and adding solid $NH_3OHF$. This new compound has been characterized by chemical and thermal analysis, single-crystal X-ray diffraction, and magnetic measurements. The title compound crystallizes trigonal, R3c, with cell parameters a = 11.4154(2) Å, c = 11.5720(2) Å, Z = 6. The structure consists of $NH_3OH^+$ cations and isolated $FeF_6^{3–}$ octahedra in which the central ion lies on a threefold axis. The oxygen and nitrogen atoms of the hydroxylammonium cations are donors of hydrogen bonds to fluoride anions, resulting in a network of hydrogen bonds between counterions. The effective magnetic moment $µ_{eff}$ = 5.8 BM was calculated and perfectly matches the expected value of high-spin Fe(III) ions. The thermal decomposition of the compound was studied by TG, DSC, and X-ray powder diffraction.
Keywords: inorganic chemistry, crystallography, coordination compounds, synthesis, crystal structure, characterization of compounds, determination of the structure of compounds, X-ray diffraction, magnetic measurements, thermal analysis, TG, DSC, hydrogen bond, metal complexes, hydroxylammonium fluoromethalatehydroxylammonium, fluoroferrate
Published: 25.08.2017; Views: 1165; Downloads: 53
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6.
A silver/silver sulphide selective electrode prepared by means of chemical treatments of silver wire
Danilo Dobčnik, Igor Gros, Mitja Kolar, 1998, original scientific article

Abstract: The preparation and usability of a sulphide ion selective electrode, prepared by means of chemical pretreatment of silver wire with an ammonium perdisulphate solution, and the sulphidization in an alkaline sulphide solution are described. The electrode is suitable for direct potentiometric measuring of sulphide in alkaline solutions of concentrations down to ▫$1 X 10^{-6} mol/L$▫. The 45 min required for each chemical treatment are enough for the preparation of the described electrode.
Keywords: analytical chemistry, ion selective electrode, preparation, silver wire, potentiometric measurements, sulphide ions
Published: 17.08.2017; Views: 627; Downloads: 78
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7.
Force measurements on teeth using fixed orthodontic systems
Rebeka Rudolf, Janko Ferčec, 2013, review article

Abstract: The fixed orthodontic appliance consists of brackets that are bonded to the teeth. When the wire is engaged in the slot of the brackets, it generates forces for orthodontic tooth movement. The change in periodontal blood supply provides a biological response which leads to remodelling of the alveolar bone and the orthodontic tooth movement. Many variables influencing orthodontic treatment cannot be controlled fully, such as growth and tissue response to appliances. However, the force placed on the tooth should be a controllable variable, and a careful study of the physics underlying clinical applications can help in reducing undesirable side effects. The properties of orthodontic wires such as: strength, stiffness, elasticity and spring-back define their clinical usefulness. The ideal orthodontic wire should exhibit the following properties: large spring-back, low stiffness, good formability, high stored energy, biocompatibility and environmental stability, low surface friction, and the capability of being welded or soldered to auxiliaries. The ideal arch wire has not been introduced yet. Once the wire is activated or bent, it is the unloading or deactivating forces that produce the orthodontic tooth movement. For these reasons, it is necessary to know the force level caused by each individual wire used in orthodontic treatment. Finally, the purpose of this paper is a presentation of force measurements which are generated by different super-elasticity NiTi wires.
Keywords: force measurements, orhodontic system, teeth, NiTi alloys
Published: 09.08.2017; Views: 622; Downloads: 266
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8.
The different methods of displacement monitoring at loading tests of bridges or different structures
Boštjan Kovačič, Rok Kamnik, Andrii Bieliatynskyi, 2016, published scientific conference contribution

Abstract: By measuring the displacements and deformations at different structures we deal in the Faculty of Civil Engineering, transportation Engineering and Architecture in University of Maribor for about 20 years. At that time we measured over 600 structures. Most loading tests of bridges and Viaducts were made. The measurements of movements needed to be as precise and accurate as possible. To do that laboratory test of instruments were made to see which instrument gives us reliable results. Displacements can be determined by geodetic and physical methods, depends of the construction. The use of geodetic methods are still preferable. In the paper the measurements with the total station, the level and rotation level, photogrammetry and solutions on the field by physical methods with inductive transducers are presented. We need to measure displacements as quick as possible but efficiently because we can not repeat the measurements under the same conditions. Also the surveying on the bridge and in the lab with the comparison of methods is presented under the different hard terrain conditions - water beneath the construction, big height of the structure, unapproachability, large span structures.
Keywords: bridges, measurements, strain gauge, load test, deformation, strain, signal processing
Published: 02.08.2017; Views: 706; Downloads: 253
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9.
Physical self-concept, anthropometry and body composition in preadolescents
Stojan Puhalj, Črtomir Matejek, Jurij Planinšec, 2013, original scientific article

Abstract: The main aim of this study was to determine the relationship of morphologic features and body composition to physical self-concepts in boys and girls separately. This research included 630 children from north-eastern Slovenia, aged 9 to 11 years (M = 10.01; SD = .810), of which 311 were boys and 319 were girls. Morphologic features of the children were measured with the use of a standardized anthropometric instrumentation; the Maltron BF-907 Body Composition Analyzer was used for the measurement of body fat, fat-free mass, and body water proportions. The gender, age, and physical self-concept data were acquired through the French version of The Physical Self-Inventory – a short form questionnaire for determining the physical self-concept of adolescents, adapted to Slovenia. The relation between individual morphological features and physical self-concept was determined by regression analysis. Statistical significance was established at 0.05. The results show that the physical self-concept is more closely connected with body composition and morphologic features in boys than in girls, whereas the body fat proportion is the strongest predictor of physical self-concept in boys. The findings show that, particularly in boys, the physical self-concept is also largely based on the morphologic features and body composition. It is necessary to give special attention to boys, as we often think that boys are not as concerned with the physical appearance as girls.
Keywords: self-concept, physical development, body measurements, body fat, pupils
Published: 21.07.2017; Views: 823; Downloads: 88
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10.
Sensor for injection rate measurements
Milan Marčič, 2006, original scientific article

Abstract: A vast majority of the medium and high speed Diesel engines are equipped with multi-hole injection nozzles nowadays. Inaccuracies in workmanship and changing hydraulic conditions in the nozzles result in differences in injection rates between individual injection nozzle holes. The new deformational measuring method described in the paper allows injection rate measurement in each injection nozzle hole. The differences in injection rates lead to uneven thermal loads of Diesel engine combustion chambers. All today known measuring method, such as Bosch and Zeuch give accurate results of the injection rate in diesel single-hole nozzles. With multihole nozzles they tellus nothing about possible differences in injection rates between individual holes of the nozzle. At deformational measuring method, the criterion of the injected fuel is expressed by the deformation of membrane occurring due to the collision of the pressure wave against the membrane. The pressure wave is generated by the injection of the fuel into the measuring space. For each hole of the nozzle the measuring device must have a measuring space of its own into which fuel is injected as well as its measuring membraneand its own fuel outlet. During measurements procedure the measuring space must be filled with fuel to maintain an overpressure of 5 kPa. Fuel escaping from the measuring device is conducted into the graduated cylinders for measuring the volumetric flow through each hole of the nozzle.The membrane deformation is assessed by strain gauges. They are glued to the membrane and forming the full Wheatstonećs bridge. We devoted special attention to the membrane shape and temperature compensation of the strain gauges.
Keywords: thermodynamics, sensors, Diesel engines, nozzles, injection, measurements
Published: 22.06.2017; Views: 858; Downloads: 276
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