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71.
Gilberto Gonzalez Avalos Gerardo Ayala Noe Barrera Gallegos Aaron Padilla Jose 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2019,25(3):284-332
Based on non-linear systems described by multibond graphs, a procedure designed to present symbolic linearization of these multibond graphs, is presented in this paper. Firstly, a junction structure of a multibond graph with multiport gyrators that represent Eulerian junction structures is proposed. In addition, non-linear multiport resistors are considered. By knowing the non-linear causal paths and loops of the non-linear multibond graph, the linearization is obtained by two steps: (1) The original multibond graph on the nominal operating point is evaluated; (2) New and additional paths based on the non-linear causal paths and loops are included. The state space representation of the linearized multibond graph using the corresponding junction structure is presented. An advantage of this methodology is its ability to allow the user to define a nominal operating point in which the linearization will be carried out.
In order to apply the proposed methodology, two physical systems are modelled and linearized by multibond graphs: a synchronous generator and a two degrees of freedom PUMA. Simulation results of these non-linear and linearized systems are shown. 相似文献
72.
In this research we apply an analytic approach to solve the well-known Lorenz system in the non-chaotic regime. The proposed approach is based on modal expansion by infinite series. The analytical-numerical results show that for real initial conditions and under the non-convective regime the modal expansion series reproduce correctly the dynamical behavior of the solution of the Lorenz system. The validity and reliability of the proposed analytical approach with few terms is tested by its application to the convective and non-convective regime with various parameter values. The main advantage is that the obtained solution is global and is presented in analytical form. 相似文献
73.
López C. Herrasti P. Sánchez M. Casillas N. 《Journal of Solid State Electrochemistry》2017,21(11):3345-3354
Journal of Solid State Electrochemistry - In this work, an electrochemical modified microcell is proposed to obtain local mass transfer coefficients at microscopic electrode areas. Microcell... 相似文献
74.
75.
Mônica F. Belian Ricardo O. Freire Gilberto F. de Sá Severino Alves Jr. 《Journal of luminescence》2010,130(10):1946-1442
A new Eu(III)/Tb(III) binuclear coordination compound with red and yellow emissions in solution and solid state, respectively, has been prepared. The lanthanide (Ln) ions are coordinated to crown ethers (C) and bridged by a dipyridyl (dipy) ligand. Ln/C and Ln/C/dipy complexes were also synthesized as precursors for the bimetallic compounds. The homo- and heterobimetallic Ln(III) complexes were characterized by elemental analysis as well as infra-red, absorption (UV-visible) and emission spectroscopies. The heterobimetallic complex geometry was predicted using the Sparkle/AM1 model and suggested to a chemical environment of very low symmetry around the lanthanide ions (C1), in agreement with the luminescence spectrum. The Eu(III) and Tb(III) complexes display intense red and green emissions, respectively, in the solid state at room temperature. 相似文献
76.
Muhammad I. M. Abdul Khudus Timothy Lee Tianye Huang Xuguang Shao Ping Shum Gilberto Brambilla 《Fiber and Integrated Optics》2015,34(1-2):53-65
AbstractIntermodally phase-matched up- and down-conversion processes based on third-order non-linearity have been proposed to efficiently generate light in the ultraviolet (UV) and mid-infrared (IR) wavelength regions in solid-core silica optical fibers and optical microfibers. Waveguide parameters and practical considerations required for optimum conversion are studied. 相似文献
77.
We consider the study of an eigenvalue problem obtained by linearizing about solitary wave solutions of a Boussinesq equation. Instead of using the technique of Evans functions as done by Pego and Weinstein in [R. Pego and M. Weinstein, Convective Linear Stability of Solitary Waves for Boussinesq equation. AMS, 99, 311–375] for this particular problem, we perform Fourier analysis to characterize solutions of the eigenvalue problem in terms of a multiplier operator and use the strong relationship between the eigenvalue problem for the linearized Boussinesq equation and the eigenvalue problem associated with the linearization about solitary wave solutions of a special form of the KdV equation. By using a generalization of the Rouché Theorem and the asymptotic behavior of the Fourier symbol corresponding to the eigenvalues problem for the Boussinesq equation and the Fourier symbol corresponding to the eigenvalues problem for the KdV equation, we show nonexistence of eigenvalues with respect to weighted space in a planar region containing the right-half plane. 相似文献
78.
An original HPLC method coupled to spectrofluorimetric detection is presented for the simultaneous analysis in dried blood spots (DBS) of cocaine and two important metabolites, namely benzoylecgonine (its main metabolite) and cocaethylene (the active metabolite formed in the presence of ethanol). The chromatographic analysis was carried out on a C8 column, using a mobile phase containing phosphate buffer (pH 3.0)-acetonitrile (85:15, v/v). Native analyte fluorescence was monitored at 315 nm while exciting at 230 nm. A fast and feasible sample pre-treatment was implemented by solvent extraction, obtaining good extraction yields (>91%) and satisfactory precision values (RSD<4.8%). The method was successfully applied to DBS samples collected from some cocaine users, both with and without concomitant ethanol intake. The results were in good agreement with those obtained from plasma samples subjected to an original solid-phase extraction procedure on C8 cartridges. The method has demonstrated to be suitable for the monitoring of cocaine/ethanol use by means of DBS or plasma testing. Assays are in progress to apply this method on the street, for the control of subjects suspected of driving under the influence of psychotropic substances. 相似文献
79.
Maria Addolorata Saracino Chiara Marcheselli Lorenzo Somaini Gilberto Gerra Francesco De Stefano Maria Chiara Pieri Maria Augusta Raggi 《Analytical and bioanalytical chemistry》2010,398(5):2155-2161
An isocratic high-performance liquid-chromatographic method has been developed for the simultaneous determination of disulfiram
and bupropion in human plasma samples. Analyses were carried out on a C8 reversed-phase column using a mobile phase composed of 50% acetonitrile and 50% aqueous phosphate buffer, containing triethylamine.
Diode-array detection was used, operating at a wavelength of 250 nm. For the clean-up of plasma samples, a solid phase extraction
procedure, based on C2 cartridges, was implemented. Extraction yields of the analytes were satisfactory, being always higher than 84%. The calibration
curve was linear over the 5–500 ng mL-1 plasma concentration range for both disulfiram and bupropion. The method showed a high sensitivity (limit of detection of
1.5 ng mL-1) and satisfactory precision, selectivity and accuracy. The application to human plasma samples obtained from some alcohol
and nicotine abusers also gave good results. 相似文献
80.
Gilberto M. Kremer 《Physica A》2010,389(19):4018-4025
The aim of this work is to analyze the entropy, entropy flux and entropy rate of granular materials within the frameworks of the Boltzmann equation and continuum thermodynamics. It is shown that the entropy inequality for a granular gas that follows from the Boltzmann equation differs from the one of a simple fluid due to the presence of a term which can be identified as the entropy density rate. From the knowledge of a non-equilibrium distribution function-valid for processes closed to equilibrium-it is obtained that the entropy density rate is proportional to the internal energy density rate divided by the temperature, while the entropy flux is equal to the heat flux vector divided by the temperature. A thermodynamic theory of a granular material is also developed whose objective is the determination of the basic fields of mass density, momentum density and internal energy density. The constitutive laws are restricted by the principle of material frame indifference and by the entropy principle. Through the exploitation of the entropy principle with Lagrange multipliers, it is shown that the results obtained from the kinetic theory for granular gases concerning the entropy density rate and entropy flux are valid in general for processes close to equilibrium of granular materials, where linearized constitutive equations hold. 相似文献