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991.
Eduardo Parrilla Jaime Riera Juan-R. Torregrosa Jos-L. Hueso 《Mathematical and Computer Modelling》2009,50(5-6):823
In this paper, we study simple algorithms for three-dimensional tracking objects in a stereo video sequence, by combining optical flow and stereo vision. This method is not able to handle the occlusion of the moving objects when they disappear due to an obstacle. To improve the performance of this method, we propose the use of adaptive filters and neural networks to predict the expected instantaneous velocities of the objects. In the previous works, this system has been successfully proved in two-dimensional tracking. 相似文献
992.
Eduardo Rodriguez Juan Carlos Echeverria Jose Alvarez-Ramirez 《Chaos, solitons, and fractals》2009,39(2):882-888
This communication presents a recursive algorithm for generating streams of 1/fα fractal noise, by means of fractional integration/differentiation of a white noise signal. The quality of correlated and anticorrelated noise obtained by this approach is evaluated by applying detrended fluctuation analysis. 相似文献
993.
Pedro R. García‐Morán Gabriel Jaramillo‐Soto Martha E. Albores‐Velasco Eduardo Vivaldo‐Lima 《大分子反应工程》2009,3(1):58-70
A study on the effect of process conditions and composition of the reacting mixture on the kinetics and particle properties in the copolymerization of styrene and divinylbenzene in supercritical carbon dioxide is presented. Polystyrene‐block‐polydimethylsiloxane and Krytox 257 FSL (Dupont) were used as stabilizers, and their performance compared. A 38 mL, high‐pressure view cell, equipped with one frontal and two lateral sapphire windows, was used as the reacting vessel. The polymer product was characterized for total monomer conversion, gel content, molecular weight averages of the sol fraction and particle size distribution. Acceptable polymerization rates and partially‐agglomerated spherical particles were produced under the conditions tested.
994.
Shaft Corrêa Pinto Humberto Ribeiro Bizzo Eduardo Dellacassa Fabio Luiz Paranhos Costa Suzana Guimarães Leitão 《Tetrahedron letters》2009,50(33):4785-4787
(−)-epi-Presilphiperfolan-1-ol, (1), a new triquinane sesquiterpene, was isolated from the essential oil of Anemia tomentosa var. anthriscifolia by column chromatography. Its structure elucidation was accomplished by extensive 1D- and 2D-NMR analyses, as well as by GC-MS, chiral bidimensional GC, dehydration reactions, and a comparative (GIAO/DFT) theoretical study of the 13C NMR chemical shifts of 1 and its known isomers (presilphiperfolan-1-ol (1a), presilphiperfolan-8-ol (3), and presilphiperfolan-9-ol (4)). 相似文献
995.
Pedro I. da S. Maia Fernando R. Pavan Clarice Q.F. Leite Sebastião S. Lemos Gerimário F. de Sousa Alzir A. Batista Otaciro R. Nascimento Javier Ellena Eduardo E. Castellano Elke Niquet Victor M. Deflon 《Polyhedron》2009
The development of more efficient anti-tuberculosis drugs is of interest. Three oxovanadium(IV) and three cis-dioxovanadium(V) complexes with thiosemicarbazone derivatives bearing moieties with different lipophilicity have been prepared and had their inhibitory activity against Mycobacteriumtuberculosis H37Rv ATCC 27294 evaluated. The analytical methods used by the complexes’ characterization included IR, EPR, 1H, 13C and 51V NMR spectroscopies, elemental analysis, cyclic voltammetry, magnetic susceptibility measurement and single crystal X-ray diffractometry. [VO(acac)(aptsc)], [VO(acac)(apmtsc)] and [VO(acac)(apptsc)] (acac = acetylacetonate; Haptsc = 2-acetylpyridinethiosemicarbazone; Hapmtsc = 2-acetylpyridine-N(4)-methyl-thiosemicarbazone and Happtsc = 2-acetylpyridine-N(4)-phenyl-thiosemicarbazone) are paramagnetic and their EPR spectra are consistent with the monoanionic N,N,S-tridentate coordination of the thiosemicarbazone ligands, resulting in octahedral structures of rhombic symmetry and with the oxidation state +IV for the vanadium atom. As result of oxidation of the vanadium(IV) complexes above, the diamagnetic cis-dioxovanadium(V) complexes [VO2(aptsc)], [VO2(apmtsc)] and [VO2(apptsc)] are formed. Their 1H, 13C and 51V NMR spectra were acquired and support a distorted square pyramidal geometry for them, in accord with the solid state X-ray structures determined for [VO2(aptsc)] and [VO2(apmtsc)]. In general, the vanadium compounds show comparable or larger anti-M. tuberculosis activities than the free thiosemicarbazone ligands, with MIC values within 62.5–1.56 (μg/mL). 相似文献
996.
Fernando Aguilar Fatima E.M. Alaoui Jos J. Segovia Miguel A. Villaman Eduardo A. Montero 《Fluid Phase Equilibria》2009,284(2):106-113
Experimental excess molar enthalpies of the ternary systems dibutyl ether (DBE) + 1-butanol + benzene and the corresponding binary systems at T = 298.15 K and T = 313.15 K at atmospheric pressure are reported. A quasi-isothermal flow calorimeter has been used to make the measurements. All the binary and the ternary systems show endothermic character. The experimental data for the binary and ternary systems have been fitted using the Redlich-Kister equation and the NRTL and UNIQUAC models. The values of the standard deviation indicate good agreement between the experimental results and those calculated from the equations. 相似文献
997.
An Efficient Semi-Analytical Method to Compute Displacements and Stresses in an Elastic Half-Space with a Hemispherical Pit 下载免费PDF全文
Valeria Boccardo Eduardo Godoy & Mario Durá n 《advances in applied mathematics and mechanics.》2015,7(3):295-322
This paper presents an efficient method to calculate the displacement and
stress fields in an isotropic elastic half-space having a hemispherical pit and being subject
to gravity. The method is semi-analytical and takes advantage of the axisymmetry
of the problem. The Boussinesq potentials are used to obtain an analytical solution
in series form, which satisfies the equilibrium equations of elastostatics, traction-free
boundary conditions on the infinite plane surface and decaying conditions at infinity.
The boundary conditions on the free surface of the pit are then imposed numerically,
by minimising a quadratic functional of surface elastic energy. The minimisation
yields a symmetric and positive definite linear system of equations for the coefficients
of the series, whose particular block structure allows its solution in an efficient and
robust way. The convergence of the series is verified and the obtained semi-analytical
solution is then evaluated, providing numerical results. The method is validated by
comparing the semi-analytical solution with the numerical results obtained using a
commercial finite element software. 相似文献
998.
Leopoldo Eduardo Cárdenas-Barrón 《Applied Mathematical Modelling》2012,36(12):6338-6340
Chang [1] [H.-C. Chang, A comprehensive note on: an economic order quantity with imperfect quality and quantity discounts, Appl. Math. Model. 35 (10) (2011) 5208-5216] corrects a flaw in Lin’s inventory model [T.Y. Lin, An economic order quantity with imperfect quality and quantity discounts, Appl. Math. Model. 34 (10) (2010) 3158–3165]. Then, he develops an algorithm to find the optimal solution for the corrected Lin’s inventory model and furthermore derives close form expressions to determining the optimal solution to an EOQ inventory model considering items with imperfect quality with different holding costs for good and defective items. In both models there is a discrete variable and he presents some inequalities in order to find the integer value. This paper provides some simple formulas to obtain, in an easy way, the integral value for the discrete variable. 相似文献
999.
1000.
We show that noise enhances the trapping of trajectories in scattering systems. In fully chaotic systems, the decay rate can decrease with increasing noise due to a generic mismatch between the noiseless escape rate and the value predicted by the Liouville measure of the exit set. In Hamiltonian systems with mixed phase space we show that noise leads to a slower algebraic decay due to trajectories performing a random walk inside Kolmogorov-Arnold-Moser islands. We argue that these noise-enhanced trapping mechanisms exist in most scattering systems and are likely to be dominant for small noise intensities, which is confirmed through a detailed investigation in the Hénon map. Our results can be tested in fluid experiments, affect the fractal Weyl's law of quantum systems, and modify the estimations of chemical reaction rates based on phase-space transition state theory. 相似文献