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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 in DKUM: 18.06.2018; Views: 1241; Downloads: 60
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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 in DKUM: 17.05.2018; Views: 1170; Downloads: 83
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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 in DKUM: 25.08.2017; Views: 1618; Downloads: 62
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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 in DKUM: 09.08.2017; Views: 989; Downloads: 325
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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 in DKUM: 21.07.2017; Views: 1619; Downloads: 126
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