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51.
Vojislav V. Mitic Zoran S. Nikolic Vladimir B. Pavlovic Vesna Paunovic Miroslav Miljkovic Branka Jordovic Ljiljana Zivkovic 《Journal of the American Ceramic Society》2010,93(1):132-137
In this article, ytterbium and erbium oxides are used as doping materials for barium titanate (BaTiO3 ) materials. The amphoteric behavior of these rare-earth ions leads to the increase of dielectric permittivity and decrease of dielectric losses. BaTiO3 ceramics doped with 0.01–0.5 wt% of Yb2 O3 and Er2 O3 were prepared by conventional solid-state procedure and sintered at 1320°C for 4 h. In BaTiO3 doped with a low content of rare-earth ions (0.01 wt%) the grain size ranged between 10 and 25 μm. With the higher dopant concentration of 0.5 wt%, the abnormal grain growth is inhibited and the grain size ranged between 2 and 10 μm. The measurements of capacitance and dielectric losses as a function of frequency and temperature have been carried out in order to correlate the microstructure and dielectric properties of doped BaTiO3 ceramics. The temperature dependence of the dielectric constant as a function of dopant amount has been investigated. 相似文献
52.
Johannes Berger Sebastian Zoran Bruschetini‐Ambro Werner David Thomas Mayrhuber 《Beton- und Stahlbetonbau》2010,105(10):631-639
Aufgrund der hohen Erhaltungskosten von Brücken gibt es mittlerweile unterschiedliche Ansätze, um die Dauerhaftigkeit zu erhöhen. Vorgespannte Brücken ohne Betonstahl stellen hierfür einen neuen Ansatz dar. Zur Erforschung des Tragverhaltens solcher Strukturen wurde ein Forschungsprojekt gestartet und Großversuche durchgeführt. Die Landesbaudirektion Salzburg war von dieser innovativen Idee überzeugt und hat deshalb die Technologie beim Bau der Egg‐Graben Brücke ausgeschrieben. Die Egg‐Graben Brücke ist eine im Grundriss gekrümmte Bogenbrücke mit einer Länge von 50 m. Nach einer Bauzeit von 18 Monaten erfolgte im November 2009 die Freigabe für den Verkehr. Der vorliegende Aufsatz beschreibt die Technologie, den Entwurf sowie die beim Bau der Brücke gesammelte Erfahrung. Design and Construction of the Egg‐Graben Bridge Due to the high maintenance costs of bridges, there are now various approaches to enhance the durability. Post tensioned bridges without steel reinforcement represent one of these approaches. To investigate the structural behaviour of such constructions, a research project was started and large‐scale tests were carried out. The government of the province of Salzburg could be convinced of this innovative technology and tendered out the method for the construction of the Egg‐Graben Bridge. For the arch bridge, which is curved in plan, the superstructure is prestressed without using further steel reinforcement. After a construction period of 18 months the bridge was opened to traffic in November 2009. The paper describes the technology, the design and the experience gained from the construction of the bridge. 相似文献
53.
54.
György Bánhegyi Páter Hedvig Zoran S. Petrović Frank E. Karasz 《Polymer-Plastics Technology and Engineering》2013,52(2-3):183-225
In this article a theoretical background for understanding dielectric phenomena in heterogeneous polymeric composites is presented, and the application of these principles to practical problems is illustrated by experimental examples. First a short overview of the existing theoretical mixing formulae is given, the differences in these approaches are discussed, and the areas of application are indicated. Conditions for the appearance of an interfacial relaxation process are delineated; limitations of the theories are given. Experimental examples include immiscible polymer blends, mineral-filled polyolefins, thermoset composites, and conductive composites. In the first example, AC dielectric spectroscopy is used to monitor the phase separation process and to evaluate interactions between the separated phases. In the second example, the effect of filler permittivity, volume fraction, and surface treatment is discussed with respect to the AC and DC dielectric properties. It is shown that in mineral-filled polyolefins, water adsorbed at the matrix-filler interface plays an important role. In the third example, the effect of filler purity (and conductivity) on the dielectric properties is demonstrated. Nonelectrical-grade glass powder causes a strong interfacial polarization and electrode polarization in an unsaturated polyester resin, whereas electrical-grade glass fiber reinforcement leads to minor property changes. In the final example, the effects of processing conditions on the AC conductivity and permittivity of conductive composites is discussed. Extensive shear and orientation cause a shift of the percolation threshold, thus reducing the conductivity. Thus it is shown that dielectric methods can be used to investigate problems in processing technology. 相似文献
55.
Ilija Obradovic 《Electrical Engineering (Archiv fur Elektrotechnik)》1942,36(6):382-390
Zusammenfassung Die Berechnung der Fläche wurde angegeben, die die Lösung einer homogenen linearen Differentialgleichung beliebiger Ordnung, die eine stabile Bewegung darstellt, im Zeitintervale vont=0 bist= umschreibt. Danach ist an zwei behandelten Beispielen, die meistens bei der Schnellregelung vorkommen, gezeigt, wie diese Fläche nach einer sehr einfachen Gleichung zu bestimmen ist. Durch Vergleich der oszillographisch aufgenommenen Abweichungsflächen eines in Betrieb befindlichen Reglers kann man entweder einige Konstanten der Regelung ermitteln oder eine Rechnungskontrolle durchführen. Die Fläche kann weiterhin als ein Hilfsbegriff zu den theoretischen Untersuchungen auf dem Gebiete der Schnellregelung von Nutzen sein. 相似文献
56.
Aleksandar Jovanović Aleksandar Perović Wlodzimierz Klonowski Wlodzisław Duch Zoran Đorđević Slađana Spasić 《Journal of Signal Processing Systems》2010,60(1):115-129
In this article structures in biological signals are treated. The simpler—directly visible in the signals, which still demand
serious methods and algorithms in the feature detection, similarity investigation and classification. The major actions in
this domain are of geometric, thus simpler sort, though there are still hard problems related to simple situations. The other
large class of less simple signals unsuitable for direct geometric or statistic approach, are signals with interesting frequency
components and behavior, those suitable for spectroscopic analysis. Semantics of spectroscopy, spectroscopic structures and
research demanded operations and transformations on spectra and time spectra are presented. The both classes of structures
and related analysis methods and tools share a large common set of algorithms, all of which aiming to the full automatization.
Some of the signal features present in the brain signal patterns are demonstrated, with the contexts relevant in BCI, brain
computer interfaces. Mathematical representations, invariants and complete characterization of structures in broad variety
of biological signals are in the central focus. 相似文献
57.
Suzana Sop?i? Marijana Kralji? Rokovi? Zoran Mandi? András Róka György Inzelt 《Electrochimica acta》2011,(10):4849
Pseudocapacitance reaction of hydrous ruthenium oxide was investigated by cyclic voltammetry combined with electrochemical quartz-crystal nanobalance (EQCN) in sulfuric acid as well as in neutral solutions of Na2SO4 and K2SO4. The ruthenium oxide electrode was prepared by attaching the ruthenium oxide particles on gold covered quartz electrode. The results show that there are different types of charge taking place simultaneously during the redox reaction of ruthenium oxide electrode. Their contribution to the overall charge depends on the experimental conditions. Depending on the potential and electrolyte used the redox reaction of ruthenium oxide is accompanied either by mass loss or by mass gain. The average molar masses of the species exchanged between the solid phase and the electrolyte solution depend on the potential and scan rate. The effect of Nafion™ top layer was also investigated. It has been found that it does not affect significantly the overall specific capacitance of ruthenium oxide electrode but the apparent molar masses of exchanged species decrease in comparison with the uncovered electrodes. 相似文献
58.
Zoran Zivkovic 《Computer Vision and Image Understanding》2010,114(11):1215-1222
A multiple-camera system for 3D pose reconstruction is presented. First, body parts of the user are detected. Each camera has a single-instruction multiple-data (SIMD) processor used to perform this heavy-load image processing task. The detected hand and head candidate positions are then transmitted wirelessly from each camera to a central processor using a low-power ZigBee network. Finally, the 3D pose reconstruction is performed at the central processor by combining the data in a probabilistic manner. 相似文献
59.
60.
Tapan K. Sarkar Pallab Midya Zoran A. Maricevic Masoud Kahrizi Sadasiva M. Rao Antonije R. Djordjevic 《国际射频与微波计算机辅助工程杂志》1992,2(3):168-178
Triangular patch modeling is used for analysis of arbitrarily shaped microstrip patch antennas over a single lossy dielectric medium. Since the Sommerfeld formulation is used, both the single dielectric layer (over which the microstrip patch is located) and the ground plane are considered to be infinitely wide. Typical numerical results are presented for rectangular, circular, semicircular, pentagonal, and triangular patch antennas. © 1992 John Wiley & Sons, Inc. 相似文献