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Search Results: 1 - 10 of 22261 matches for " Eduardo Radovanovic "
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Outstanding Impact Resistance of Post-Consumer HDPE/Multilayer Packaging Composites  [PDF]
Silvia Luciana Favaro, Antonio Guilherme Basso Pereira, Janaina Rodrigues Fernandes, Orlando Baron, Cleiser Thiago Pereira da Silva, Murilo Pereira Moisés, Eduardo Radovanovic
Materials Sciences and Applications (MSA) , 2017, DOI: 10.4236/msa.2017.81002
Abstract: New recycling alternative for multilayer films was successfully presented. Food packaging formed from different materials is difficult to recycle. The use of aluminum, glass, paper, paints, varnishes, and other materials in the rolling processes from plastic packaging is intended to optimize the efficiency of packaging. Nevertheless, these materials prevent the recycling of packaging because they become contaminants to the recycling process. Food multilayered packaging containing poly (ethylene terephthalate) PET, poly (ethylene) PE and aluminum was used as filler in the preparation of composites with post-consumer high density polyethylene matrix. Composites containing up to 50 wt% of filler were feasible to prepare, allowing the obtention of a material with varied mechanical and thermal properties. This feature allows the preparation of composites suitable for specific application. The addition of multilayer matter in the polyethylene matrix provided a material with excellent mechanical properties such as higher tensile impact strength (148 J/m) and elasticity (350 MPa) as compared to pure polyethylene (40 J/m and 450 MPa).
Chemical characterization of BiFeO3 obtained by Pechini method
Ferri, Elídia A. Vetter;Santos, Ivair A.;Radovanovic, Eduardo;Bonzanini, Rafaelle;Girotto, Emerson Marcelo;
Journal of the Brazilian Chemical Society , 2008, DOI: 10.1590/S0103-50532008000600015
Abstract: this work describes the synthesis and characterization of bifeo3 obtained by the pechini route using bismuth nitrate and iron nitrate as precursors. the powders were annealed at 800 °c in air for 2 h. x-ray diffraction patterns showed that the material presents two phases, bifeo3 (95%) and α-bi2o3 (5%). the ferroelectric transition of the sample at 821 °c was detected by differential thermal analysis. results of analyses by scanning electron microscopy (sem), energy dispersive spectroscopy (eds) and energy dispersive x-ray fluorescence (edx) showed that the sample is chemically homogeneous. transmission electron microscopy images revealed that the sample is uniform and contains spherical particles with an average size of 30 nm.
Si3N4/SiC nanocomposite powder from a preceramic polymeric network based on poly(methylsilane) as the SiC precursor
Gozzi, Maurício F.;Radovanovic, Eduardo;Yoshida, I. Valéria P.;
Materials Research , 2001, DOI: 10.1590/S1516-14392001000100004
Abstract: si3n4/sic nanocomposite powders were obtained from a preceramic polymeric network based on poly(methylsilane) as the in situ quasi-stoichiometric sic source. these powders were constituted of nanosized sic particles homogeneously distributed in the si3n4 particulate matrix. b-sic whiskers were grown at 1400 °c in the pores of the matrix. at 1600 °c, the a ? b si3n4 phase transition took place, but no elemental silicon from si3n4 decomposition was detected, evidencing the protective effect of the sic phase.
Si3N4/SiC nanocomposite powder from a preceramic polymeric network based on poly(methylsilane) as the SiC precursor
Gozzi Maurício F.,Radovanovic Eduardo,Yoshida I. Valéria P.
Materials Research , 2001,
Abstract: Si3N4/SiC nanocomposite powders were obtained from a preceramic polymeric network based on poly(methylsilane) as the in situ quasi-stoichiometric SiC source. These powders were constituted of nanosized SiC particles homogeneously distributed in the Si3N4 particulate matrix. beta-SiC whiskers were grown at 1400 °C in the pores of the matrix. At 1600 °C, the alpha -> beta Si3N4 phase transition took place, but no elemental silicon from Si3N4 decomposition was detected, evidencing the protective effect of the SiC phase.
Real-Time Resource Availability Signaling in IP Multimedia Subsystem Networks  [PDF]
Tanir Ozcelebi, Igor Radovanovic, Debraj Sengupta
Journal of Service Science and Management (JSSM) , 2008, DOI: 10.4236/jssm.2008.12013
Abstract: IP Multimedia Subsystem (IMS) allows the use of unlicensed, non-dedicated and nondeterministic access networks for delivering IP multimedia services. Providing end-to-end Quality-of-Service (QoS) for resource demanding real-time services (e.g. real-time multimedia) over such networks is a challenging task due to varying resource availability of the network and the end-device during a single session . A common solution to this problem is adapting service quality and type according to availability of system resources, which requires end-to-end monitoring and signaling of resource availability during a single session. This paper presents an extension of the IMS architecture for real-time resource availability monitoring and signaling. The novelty of the proposed extension is twofold. It takes into account uncon-trolled access networks with no resource reservation on the one hand, and end devices on the other. Two system archi-tecture components are introduced for monitoring and signaling of the real-time resource availability in both networks (e.g. bandwidth, buffer space), and end-devices (e.g. battery, CPU, memory, storage), namely a Resource Manager (RM) and a Resource Availability Server (RAS). Our solution does not require any modifications of the IMS architec-ture and can be implemented as a plug-in.
Synthesis of Ag-PVA and Ag-PVA/PET-s20 composites by supercritical CO2 method and study of silver nanoparticle growth
Silva, Rafael;Kunita, Marcos H.;Girotto, Emerson M.;Radovanovic, Eduardo;Muniz, Edvani C.;Carvalho, Gizilene M.;Rubira, Adley F.;
Journal of the Brazilian Chemical Society , 2008, DOI: 10.1590/S0103-50532008000600025
Abstract: supercritical co2 has been used to prepare silver polymer composites, silver/poly(vinyl alcohol) and silver/poly(vinyl alcohol)/sulfonated poly(ethylene terephthalate) through impregnation of a silver precursor in solid-state polymeric matrices followed by thermal reduction of the silver precursor. x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy, thermogravimetric analysis and uv/vis spectroscopy indicate that synthesis conditions and polymeric matrix composition affect silver particle size, shape and distribution in polymeric matrices. silver particles are smaller, have a more uniform shape and present narrower size distribution in pva-rich than in pets-rich composites.
Two-loop Back-reaction in 2D Dilaton Gravity
A. Mikovic,V. Radovanovic
Physics , 1996, DOI: 10.1016/S0550-3213(96)00528-7
Abstract: We calculate the two-loop quantum corrections, including the back-reaction of the Hawking radiation, to the one-loop effective metric in a unitary gauge quantization of the CGHS model of 2d dilaton gravity. The corresponding evaporating black hole solutions are analysed, and consistent semi-classical geometries appear in the weak-coupling region of the spacetime when the width of the matter pulse is larger then the short-distance cutoff. A consistent semi-classical geometry also appears in the limit of a shock-wave matter. The Hawking radiation flux receives non-thermal corrections such that it vanishes for late times and the total radiated mass is finite. There are no static remnants for matter pulses of finite width, although a BPP type static remnant appears in the shock-wave limit. Semi-classical geometries without curvature singularities can be obtained as well. Our results indicate that higher-order loop corrections can remove the singularities encountered in the one-loop solutions.
Loop Corrections in the Spectrum of 2D Hawking Radiation
A. Mikovic,V. Radovanovic
Physics , 1997, DOI: 10.1088/0264-9381/14/9/019
Abstract: We determine the one-loop and the two-loop back-reaction corrections in the spectrum of the Hawking radiation for the CGHS model of 2d dilaton gravity by evaluating the Bogoliubov coefficients for a massless scalar field propagating on the corresponding backgrounds. Since the back-reaction can induce a small shift in the position of the classical horizon, we find that a positive shift leads to a non-Planckian late-time spectrum, while a null or a negative shift leads to a Planckian late-time spectrum in the leading-order stationary-point approximation. In the one-loop case there are no corrections to the classical Hawking temperature, while in the two-loop case the temperature is three times greater than the classical value. We argue that these results are consistent with the behaviour of the Hawking flux obtained from the operator quantization only for the times which are not too late, in accordance with the limits of validity of the semiclassical approximation.
Loop Corrections for 2D Hawking Radiation
A. Mikovic,V. Radovanovic
Physics , 1997,
Abstract: We describe how the reduced phase space quantization of the CGHS model of 2d black hole formation allows one to calculate the backreaction up to any finite order in matter loops. We then analyze the backreaction in the Hawking radiation up to two loops. At one-loop order the Hawking temperature does not change, while at two-loop order the temperature increases three times with respect to the classical value. We argue that such a behavior is consistent with the behaviour of the operator quantization Hawking flux for times which are not too late. For very late times the two-loop flux goes to zero which indicates that the backreaction can stop the black hole evaporation.
The one-loop effective action for quantum electrodynamics on noncomutative space
Maja Buric,Voja Radovanovic
Physics , 2002, DOI: 10.1088/1126-6708/2002/10/074
Abstract: In this paper we calculate the divergent part of the one loop effective action for QED on noncommutative space using the background field method. The effective action is obtained up to the second order in the noncommutative parameter theta and in the classical fields.
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