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Karan B.,Serbian Institute of Technical Sciences
21st International Conference in Central Europe on Computer Graphics, Visualization and Computer Vision, WSCG 2013 - Poster Proceedings | Year: 2013

Accuracy of depth measurement with Microsoft Kinect and similar 3D vision sensors depends on variations in sensor production. Sensor reading may show significant systematic errors that can be compensated in software by using an adequate depth calibration model. This paper presents one such model and a procedure for identification of its parameters. An example calibration is given to illustrate the procedure and the attained improvements. Source

Terzic A.,Serbian Institute for Materials Testing | Andric L.,Serbian Institute of Technical Sciences | Mitic V.,Serbian Institute for Technology of Nuclear and other Raw Mineral Materials
Ceramics International | Year: 2014

A growing demand for refractory castables with advanced properties has given rise to a continuous technological evolution and highlighted the necessity for secondary raw materials reapplication even in refractory industry. For the experiment, refractory shotcretes with the same matrix composition were prepared from 30 wt% of high aluminate cement, 40 wt% of bauxite aggregate and 30 wt% of chamotte filler. The request for obtaining a low-cement castable is fulfilled by application of mechanically activated coal ash as microfiller in one of the bauxite shotcretes. The fly ash was activated by means of vibratory disc mill and ultra-centrifugal mill, and results were compared. The shotcrete samples were dried at 110 °C during 24 h to create specimens for investigation of mechanical and thermal properties. The properties have been studied at temperatures ranging from room temperature to adopted maximal temperature 1400 °C. At maximal 1400 °C, the bauxite shotcretes were mainly composed of anorthite, corundum, mullite and cristobalite. Mechanisms of hydration and sintering were investigated by means of differential thermal analysis (DTA) at three different heating rates. DTA measurements showed different activation energies for ordinary bauxite shotcrete and shotcrete with microfiller. The evolution of the refractory shotcretes properties was investigated and correlated with microstructural changes induced by temperature and microfiller addition. The combination of advantages in investigated refractory shotcretes makes them suitable for use in severe conditions at high temperature applications especially in refractory industries. © 2014 Elsevier Ltd and Techna Group S.r.l. Source

Vujkovic M.,University of Belgrade | Jugovic D.,Serbian Institute of Technical Sciences | Mitric M.,Vinca Institute of Nuclear Sciences | Stojkovic I.,University of Belgrade | And 2 more authors.
Electrochimica Acta | Year: 2013

The nitrate-(glycine + malonic acid)-assisted gel-combustion process, followed by a heat treatment at 750°C under reductive atmosphere, was used as a fast and effective way to synthesize vanadium dopedolivine incorporated in carbon matrix, of general formula LiFe(1-x)VxPO 4/C. The two-phased Rietveldrefinement confirmed that vanadium incorporation into olivine structure was complete. The heatingunder reduction atmosphere caused the formation of iron phosphide to some extent, the concentrationwas determined by Rietveld analysis. The capacity and rate capability of these composites were testedby both cyclic voltammetry and galvanostatic cycling. Specifically, the average discharging capacities ofthe composite with x = 0.055, determined in an saturated aqueous LiNO3 solution equilibrated with air,at the rates of 1, 10 and 100 C, amounted to 91, 73 and 35 mAh g-1, respectively, with no perceivablecapacity fade. © 2013 Elsevier Ltd. All rights reserved. Source

Paunovic V.,University of Nis | Mitic V.V.,University of Nis | Mitic V.V.,Serbian Institute of Technical Sciences | Prijic Z.,University of Nis | Zivkovic L.,University of Nis
Ceramics International | Year: 2014

Dy/Mn doped BaTiO3 with different Dy2O3 contents, ranging from 0.1 to 5.0 at% Dy, were investigated regarding their microstructural and dielectric characteristics. The content of 0.05 at% Mn was constant in all the investigated samples. The samples were prepared by the conventional solid state reaction and sintered at 1290, and 1350 C in air atmosphere for 2 h. The low doped samples (0.1 and 0.5 at% Dy) exhibit mainly fairly uniform and homogeneous microstructure with average grain sizes ranged from 0.3 μm to 3.0 μm. At 1350 C, the appearance of secondary, abnormal, grains in the fine grain matrix and core-shell structure were observed in highly doped Dy/BaTiO3. Dielectric measurements were carried out as a function of temperature up to 180 C. The low doped samples sintered at 1350 C, display the high value of dielectric permittivity at room temperature, 5600 for 0.1Dy/BaTiO3. A nearly flat permittivity-temperature response was obtained in specimens with 2.0 and 5.0 at% additive content. Using a Curie-Weiss and modified Curie-Weiss low, the Curie constant (C), Curie like constant (C′), Curie temperature (TC) and a critical exponent (γ) were calculated. The obtained values of γ pointed out the diffuse phase transformation in highly doped BaTiO3 samples. © 2013 Elsevier Ltd and Techna Group S.r.l. Source

Mancic L.,Serbian Institute of Technical Sciences | Lojpur V.,Vinca Institute of Nuclear Sciences | Marinkovic B.A.,Pontifical Catholic University of Rio de Janeiro | Dramicanin M.D.,Vinca Institute of Nuclear Sciences | Milosevic O.,Serbian Institute of Technical Sciences
Optical Materials | Year: 2013

Examples of (Y2O3-Gd2O3): Eu3+ and Y2O3:(Yb3+/Er3+) rare earth oxide-based phosphors are presented to highlight the controlled synthesis of 1D and 2D nanostructures through simple hydrothermal method. Conversion of the starting nitrates mixture into carbonate hydrate phase is performed with the help of ammonium hydrogen carbonate solution during hydrothermal treatment at 200 C/3 h. Morphological architectures of rare earth oxides obtained after subsequent powders thermal treatment at 600 and 1100 C for 3 and 12 h and their correlation with the optical characteristics are discussed based on X-ray powder diffractometry, field emission scanning electron microscopy, infrared spectroscopy and photoluminescence measurements. Strong red and green emission followed by the superior decay times are attributed to the high powders purity and homogeneous dopants distribution over the host lattice matrix. © 2013 Elsevier B.V. All rights reserved. Source

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