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131.
N. A. Santos R. Rosenhaim M. B. Dantas T. C. Bicudo E. H. S. Cavalcanti A. K. Barro I. M. G. Santos A. G. Souza 《Journal of Thermal Analysis and Calorimetry》2011,103(2):501-506
The synthesis of pigments from the system Ce1−x
O2–M
x
O (M = Cu, Co) was achieved via a polymeric precursors method, Pechini method. Differential scanning calorimetry (DSC) and
thermogravimetry (TG) techniques were used to accurately characterize the distinct thermal events occurring during synthesis.
The TG and DSC results revealed a series of decomposition temperatures due to different exothermal events, which were identified
as H2O elimination, organic compounds degradation, and phase formation. X-Ray diffraction patterns show the presence of pure cubic
CeO2 phase for the samples with low Cu and Co loading. A decrease of the specific surface area with increasing copper and cobalt
content was observed. The UV–visible diffuse reflectance technique was employed to study the optical properties in the 200–800 nm
range. Colorimetric coordinates L*, a*, b* were calculated for the pigment powders. The powders presented a variety of colors from yellow for pure CeO2, to brown for the ones loaded with copper and gray for the ones with cobalt. 相似文献
132.
Paulo S.G. de Mattos Neto David A. SilvaTiago A.E. Ferreira George D.C. Cavalcanti 《Physica A》2011,390(20):3444-3453
The gain or loss of an investment can be defined by the movement of the market. This movement can be estimated by the difference between the magnitudes of two stock prices in distinct periods and this difference can be used to calculate the volatility of the markets. The volatility characterizes the sensitivity of a market change in the world economy. Traditionally, the probability density function (pdf) of the movement of the markets is analyzed by using power laws. The contributions of this work is two-fold: (i) an analysis of the volatility dynamic of the world market indexes is performed by using a two-year window time data. In this case, the experiments show that the pdf of the volatility is better fitted by exponential function than power laws, in all range of pdf; (ii) after that, we investigate a relationship between the volatility of the markets and the coefficient of the exponential function based on the Maxwell-Boltzmann ideal gas theory. The results show an inverse relationship between the volatility and the coefficient of the exponential function. This information can be used, for example, to predict the future behavior of the markets or to cluster the markets in order to analyze economic patterns. 相似文献
133.
In this Letter, a new method for avalanche photodiode characterization, based on the spectral analysis of the photocurrent produced during an avalanche, is proposed. The theory is developed, and an experimental characterization of an avalanche photodiode working in the Geiger mode with CW laser is performed. 相似文献
134.
V. A. J. Silva P. L. Andrade Angel Bustamante L. de los Santos Valladares M. Mejia I. A. Souza K. P. S. Cavalcanti M. P. C. Silva J. Albino Aguiar 《Hyperfine Interactions》2014,224(1-3):227-238
Fucan-coated magnetite (Fe3O4) nanoparticles were synthesized by the co-precipitation method and studied by Mössbauer spectroscopy and magnetic measurements. The sizes of the nanoparticles were 8–9 nm. Magnetization measurements and Mössbauer spectroscopy at 300 K revealed superparamagnetic behavior. The magnetic moment of the Fe3O4 is partly screened by the Fucan coating aggregation. When the magnetite nanoparticles are capped with oleic acid or fucan, reduced particle-particle interaction is observed by Mössbauer and TEM studies. The antitumoral activity of the fucan-coated nanoparticles were tested in Sarcoma 180, showing an effective reduction of the tumor size. 相似文献
135.
Marcelo?M.?CavalcantiEmail author Valéria?N.?Domingos?Cavalcanti Andrei?Faminskii Fábio?Natali 《Applied Mathematics and Optimization》2012,65(2):221-251
In the present paper we establish results concerning the decay of the energy related to the damped Korteweg–de Vries equation
posed on infinite domains. We prove the exponential decay rates of the energy when a initial value problem and a localized
dissipative mechanism are in place. If this mechanism is effective in the whole line, we get a similar result in H
k
-level, k∈ℕ. In addition, the decay of the energy regarding a initial boundary value problem posed on the right half-line, is obtained
considering convenient a smallness condition on the initial data but a more general dissipative effect. 相似文献
136.
Marcelo M. Cavalcanti Valéria N. Domingos Cavalcanti Ryuichi Fukuoka Daniel Toundykov 《Journal of Evolution Equations》2009,9(1):143-169
This paper is devoted to the study of uniform energy decay rates of solutions to the wave equation with Cauchy–Ventcel boundary
conditions:
where Ω is a bounded domain of (n ≥ 2) having a smooth boundary , such that with , being closed and disjoint. It is known that if a(x) = 0 then the uniform exponential stability never holds even if a linear frictional feedback is applied to the entire boundary of the domain [see, for instance, Hemmina (ESAIM, Control Optim Calc Var 5:591–622, 2000, Thm. 3.1)]. Let be a smooth function; define ω
1 to be a neighbourhood of , and subdivide the boundary into two parts: and . Now, let ω
0 be a neighbourhood of . We prove that if a(x) ≥ a
0 > 0 on the open subset and if g is a monotone increasing function satisfying k|s| ≤ |g(s)| ≤ K|s| for all |s| ≥ 1, then the energy of the system decays uniformly at the rate quantified by the solution to a certain nonlinear ODE dependent
on the damping [as in Lasiecka and Tataru (Differ Integral Equ 6:507–533, 1993)].
Research of Marcelo M. Cavalcanti was partially supported by the CNPq Grant 300631/2003-0.
Research of Valéria N. Domingos Cavalcanti was partially supported by the CNPq Grant 304895/2003-2. 相似文献