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11.
Mojsilovic A. Kovacevic J. Kall D. Safranek R.J. Kicha Ganapathy S. 《IEEE transactions on image processing》2000,9(3):417-431
We determine the basic categories and the hierarchy of rules used by humans in judging similarity and matching of color patterns. The categories are: (1) overall color; (2) directionality and orientation; (3) regularity and placement; (4) color purity; (5) complexity and heaviness. These categories form the pattern vocabulary which is governed by the grammar rules. Both the vocabulary and the grammar were obtained as a result of a subjective experiment. Experimental data were interpreted using multidimensional scaling techniques yielding the vocabulary and the hierarchical clustering analysis, yielding the grammar rules. Finally, we give a short overview of the existing techniques that can be used to extract and measure the elements of the vocabulary. 相似文献
12.
E. Swietlicki K. Kemp P. Whlin J. Bartnicki L. Jalkanen Radovan Krejci 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1999,150(1-4):322-331
Atmospheric concentrations of heavy metals (HMs), in particular As, Cd, Cu, Pb and Zn, were studied in an effort to contribute to the understanding of European source-receptor relationships. A comparison was made between the ambient concentrations measured at 11 background aerosol monitoring stations (in Denmark, the Czech Republic, Finland, Norway and Sweden) and the corresponding HM concentrations estimated by the Heavy Metals Eulerian Transport (HMET) meteorological dispersion model. The collected samples were analysed with Particle Induced X-ray Emission analysis (PIXE) except the Finnish samples which were analysed with Inductively Coupled Plasma – Mass Spectrometry (ICP-MS). The available data covers the period 1985–1994. The comparison showed that the European emissions of As, Cd and Pb seem to be fairly well estimated. On the other hand, the European Zn emissions are underestimated by a factor of 3 or more, while the Cu emissions appear to be slightly overestimated. The HMET dispersion model also made it possible to select occasions for which the sampling sites had a substantial contribution of HM from the highly polluted “Black Triangle” region (on the borders between the Czech Republic, Poland and Germany). The time evolution of the sources of HMs within this source region could be studied by applying various statistical receptor models on the extensive data set from two Danish stations, Keldsnor and Tange, covering the period 1985–1994. Four source types were clearly discerned throughout the 10 year time period. These sources were: soil dust; sea spray; general combustion and oil combustion. The strong time-dependence observed for the contribution from the Black Triangle region emphasizes the importance of keeping the emission inventories continuously updated if HMs deposition calculations and HMs emissions reduction protocols are to be based on dispersion modelling approaches. 相似文献
13.
Osama Abboud Konstantin Pussep Aleksandra Kovacevic Katharina Mohr Sebastian Kaune Ralf Steinmetz 《Multimedia Systems》2011,17(3):177-197
Peer-to-Peer (P2P) techniques for multimedia streaming have been shown to be a good enhancement to the traditional client/server
methods when trying to reduce costs and increase robustness. Due to the fact that P2P systems are highly dynamic, the main
challenge that has to be addressed remains supporting the general resilience of the system. Various challenges arise when
building a resilient P2P streaming system, such as network failures and system dynamics. In this paper, we first classify
the different challenges that face P2P streaming and then present and analyze the possible countermeasures. We classify resilience
mechanisms as either core mechanisms, which are part of the system, or as cross-layer mechanisms that use information from
different communication layers, which might inflict additional costs. We analyze and present resilience mechanisms from an
engineering point of view, such that a system engineer can use our analysis as a guide to build a resilient P2P streaming
system with different mechanisms and for various application scenarios. 相似文献
14.
Aleksandra Torbica Biljana Pajin Radovan Omorjan 《Journal of the American Oil Chemists' Society》2011,88(7):937-947
The physical characteristics and color of chocolate depend on the physical properties and crystallization behavior of the
fat phase. In this study, the fat phase of chocolate samples contains cocoa butter from Ghana and soft cocoa butter equivalent
(CBE). The laboratory-made chocolate samples were tempered at three different precrystallization temperatures (25, 27 and
29 °C), using three different concentrations of CBE (3, 5 and 7%), calculated as percentage of the chocolate. Physical characteristics
of chocolate, namely thermoreographic parameters and solid fat content (SFC), were measured. The color of the chocolate was
determined instrumentally, before and after thermo-cycle testing at 32/20 °C. It was found that CBE changed the melting properties
of chocolate produced with cocoa butter from Ghana, which is of moderate hardness. It was determined that the optimum precrystallization
temperature for chocolate mass with addition of CBE in the given conditions of measurement was 27 °C, the temperature that
resulted in the best fat bloom resistance. 相似文献
15.
Radovan Novotný Radek Vlach Jaroslav Kadlec Radek Kuchta 《Microsystem Technologies》2014,20(4-5):719-728
Ceramics joints are applied for producing products that should be made in a general shapes and dimensions for more advantageous usage. The article presents the research work related to ceramic joint quality evaluation, the thermal-structural analysis of ceramic joining and ceramic bond design and implementation. The role of ceramic material in the electronics industry and motivation for joining ceramics is described in the introduction. The requirements and methods for improving the quality of joints are summarized. Also, the results of simulations of pressure sensor cooling after removal from the oven during joining are discussed. The experimental results are evaluated by using a t-test before and after process cooling modification. Important directions for future research are summarized, with emphasis on the statistical determination of poor connection, and how the interface of modification of joint technology and process setting affects results and parameters that have been achieved. 相似文献
16.
Sham Rane Ahmed Kovacevic Nikola Stosic Madhulika Kethidi 《International Journal of Refrigeration》2013,36(7):1883-1893
Customized grid generation of twin screw machines for CFD analysis is widely used by the refrigeration and air-conditioning industry today, but is currently not suitable for topologies such as those of single screw, variable pitch or tri screw rotors. This paper investigates a technique called key-frame re-meshing that supplies pre-generated unstructured grids to the CFD solver at different time steps. To evaluate its accuracy, the results of an isentropic compression-expansion process in a reciprocating piston cylinder arrangement have been compared. Three strategies of grid deformation; diffusion equation mesh smoothing, user defined nodal displacement and key-frame remeshing have been assessed. There are many limitations to key-frame re-meshing. It requires time consuming pre-processing, has limited applicability to complex meshes and leads to inaccuracies in conservation of calculated variables. It was concluded that customized tools for generation of CFD grids are required for complex screw machines. 相似文献
17.
This paper highlights the interfacial structure of tin-silver (Sn-3·5Ag) solder on nickel-coated copper pads during aging
performance studies at a temperature of 150°C for up to 96 h. Experimental results revealed the as-solidified solder bump
made from using the lead-free solder (Sn-3·5Ag) exhibited or showed a thin layer of the tin-nickel-copper intermetallic compound
(IMC) at the solder/substrate interface. This includes a sub-layer having a planar structure immediately adjacent to the Ni-coating
and a blocky structure on the inside of the solder. Aging performance studies revealed the thickness of both the IMC layer
and the sub-layer, having a planar structure, to increase with an increase in aging time. The observed increase was essentially
non-linear. Fine microscopic cracks were observed to occur at the interfaces of the planar sub-layer and the block sub-layer. 相似文献
18.
Radovan Ćirić Svetislav Čantrak Karlo T. Raić Rebeka Rudolf Ivan Anžel 《Metals and Materials International》2009,15(5):831-841
The paper presents the viscoplastic phenomena observed during the rotational friction-welding process of high-speed steel
M2 (AISI SAE) with carbon steel 1060 (AISI SAE). The structure, phase composition and distribution of the carbide phase in
the friction plane and adjoining zones are examined by using optical microscopy (OM) with a system for quantitative analysis,
and scanning electron microscopy (SEM) in addition to EDS analysis. The experimentally-checked mathematical relationship is
suggested for the calculation of the radial movements of the carbide phase, immediately next to the friction plane. On the
basis of qualitative and quantitative evaluation of the microstructural and rheological appearances, a model of carbide phase
distribution is also established in the viscoplastic and viscous layers in the area of the friction plane. 相似文献
19.
The eigenvalue control strategy, which utilizes an adaptive power system stabilizer, is presented for the decentralized control of damping and frequency of electromechanical oscillations in power systems. The control procedure includes the complete identification of the decoupled subsystem model in real-time from local measurements only and the assignment of its estimated electromechanical eigenvalue by the change of stabilizer parameters. The robustness and efficiency of the proposed adaptive controller to enhance overall system stability are illustrated by several examples, including the three-machine power system model 相似文献
20.
S. Djordjevic S. Kovacevic LJ. Nikolic M. Miljkovic D. Djordjevic 《Journal of Natural Fibers》2014,11(3):212-224
Synthesis and characterization of copolymer obtained by grafting acrylamide onto hydrolyzed potato starch and its application in cotton yarn sizing were presented in this work. Some process parameters of starch hydrolysis and grafting, like as hydrolysis yield, grafting yield, grafting percentage, graft efficiency, and monomer to polymer conversion were determinated. Molar mass values of hydrolyzed starch and copolymer samples are located in a narrow range of 1 × 105 to 1 × 107 and 1 × 102 to 1 × 104. Grafted hydrolyzed starch, as a sizing agent, gives better results than nongrafted, particularly in terms of sizing uniformity, yarn mechanical parameters, and easier removal in subsequent desizing process. 相似文献