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1.
Zia Muhammad Yousuf Irfan Otero Pablo Siddiqui Atif Poncela Javier 《Wireless Personal Communications》2021,116(2):1171-1193
Wireless Personal Communications - Underwater Wireless Sensor Networks (UWSNs) are playing a vital role in exploring the unseen underwater (UW) natural resources. However, performance evaluation of... 相似文献
2.
Edwige Croix 《Comptes Rendus Mathematique》2006,343(5):303-306
The author proves that any ideal generated by a finite number of real analytic functions in an intersection of non-quasi-analytic classes is closed for the natural Frechet topology associated to such a space. She also establishes a closedness criterion when the generators are less regular. To cite this article: E. Croix, C. R. Acad. Sci. Paris, Ser. I 343 (2006). 相似文献
3.
We present a model arising from the thermal modelling of two metal casting processes. We consider an enthalpy formulation for this two‐phase Stefan problem in a time varying three‐dimensional domain and consider convective heat transfer in the liquid phase. Then, we introduce a weak formulation in a fixed domain, by means of a suitable transformation. Existence of solution is obtained by applying an abstract theorem. The proof of this theorem is done by taking an implicit discretization in time together with a regularization. By passing to the limit in the regularization parameter and in the time step, we obtain the existence of solution of the continuous problem. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
4.
J. A. Otero H. Cálas R. Rodríguez-Ramos G. A. Maugin G. Monsiváis R. Pérez-Alvarez 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2004,55(3):519-533
The transfer matrix and global matrix techniques are
used in the analysis of diffraction of transverse horizontal waves
in piezoelectric superlattices. The system is composed of a set of
different piezoelectric layers with quasiperiodic structure
according to the Fibonacci sequence. The diffraction spectrum of
different configurations of piezoelectric Fibonacci structures is
studied. Numerical results for the diffraction spectrum for the
piezoelectric Fibonacci superlattice are obtained and a comparison
between the results of the transfer and global matrix methods is
given, exhibiting the advantage of the latter. 相似文献
5.
The solution for the two-dimensional (2-D) Green's function for a wedge with impedance faces is presented. The important feature of this Green's function is that there are no restrictions on the locations for the source and observation points-they can be anywhere. Its development proceeds along two separate lines: one for when the source or observation point is far from the wedge vertex and another one for when it is close. Much of the effort that has been expended in these formulations has been in obtaining forms for the Green's function which are efficient to evaluate numerically. This involved deforming the various contours of integration so that they are rapidly convergent and separating the contributions from the numerous singularities that occur in the integrands and evaluating them in closed form. The formulations that are employed here allow for the individual field components such as the diffracted, geometrical optics, and surface wave components to be identified and studied individually so that a physical understanding for the various scattering mechanisms for the impedance wedge can be appreciated 相似文献
6.
C. N. Carducci S. E. Lucangioli V. G. Rodríguez G. C. Fernndez Otero 《Journal of chromatography. A》1996,730(1-2):313-319
Sample preparation procedures using octadecyl (C18) extraction disks were developed to obtain accurate and reproducible results for determinations of clenbuterol (20 μg per dose) and levothyroxine (100 μg per dose) in dissolution media of solid oral dosage forms. Preconcentration of samples allowed final concentrations of 1.1 μg/ml of clenbuterol and 4.0 μg/ml of levothyroxine to be reached prior to CE analysis. The results obtained by CE were in good agreement with those of HPLC. The precision of the migration time, peak area, peak height and accuracy were determined in both intea-day (n = 6) and inter-day (n =18) assays. Linearity was demonstrated over the ranges 0.5–80.0 μg/ml of clenbuterol and 1.0–30.0 μg/ml of levothyroxine. The mean recoveries were higher than 94.0%, ranging from 50 to 125% levels with respect to dose potencies. The proposed methodology may be generally applied to determine drugs at ng/ml concentrations. 相似文献
7.
CuAl2O4, NiAl2O4, and three ternary spinels CuxNi1?xAl2O3 have been prepared, in polycrystalline form, by solid-state reaction of mixtures of CuO, NiO, and Al2O3 at 1223 K. X-Ray powder diffractometry, coupled with adequate computational methods, allowed determination of the unit-cell length, oxygen positional parameter, and cation distribution for each compound. Interdependence of these structural parameters is closely analyzed on the ternary oxide spinels. The one-electron difference between the Cu2+ and Ni2+ ions was found to be enough to render them distinguishable by X-ray powder diffraction. 相似文献
8.
Edwige Jeanneau-Nicolle Claude Bosso Martine Benoit-Guyod Grard Leclerc 《Journal of mass spectrometry : JMS》1993,28(1):37-41
The electron impact mass spectra of two series of 5-oxo-tetrahydro-5H-thiazolo [3,2-a]pyrimidine-6-ethylcarboxylates and 7-oxo-tetrahydro-7H-thiazolo [3,2-a]pyrimidine-6-ethylcarboxylates were measured and fragmentation patterns examined. Structures were assigned from analysis of oxo molecular ion fragmentations. Compounds of the 5-oxo series gave an [M – CO2C2H5]+ fragmentation whereas compounds of the 7-oxo series gave three characteristic cleavages. This decomposition was confirmed for one pair of isomers by high-resolution mass spectrometry and unimolecular mass-analysed ion kinetic energy spectrometry. Electron impact mass spectrometry is a convenient method for assigning structures of 5- and 7-oxo regioisomers of tetrahydrothiazolo[3,2-a]pyrimidine-6-carboxylates. 相似文献
9.
Castro JL López Ramírez MR López Tocón I Otero JC 《Journal of colloid and interface science》2003,263(2):357-363
Raman and SERS spectra of phenylacetic acid and alpha-phenylglycine on silver sols have been recorded at several concentrations and pH values. The alpha-phenylglycine has been also studied in D(2)O. The respective vibrational assignments have been proposed and the analysis of the SERS spectra has made it possible to conclude that phenylacetic acid links to the metal through its carboxylate group only, while alpha-phenylglycine links also through its amino group. In both cases the aromatic ring seems to be almost perpendicular to the metal surface. On the other hand, the contribution of the charge transfer (CT) mechanism to the enhancement of the SERS spectra has been calculated as well and it is found to be very important in both molecules. The band most enhanced by this mechanism is that of vibration 8a, mainly in alpha-phenylglycine. 相似文献
10.
Alvarez S Aullón G Fandos R García Fierro JL Ocón P Otero A Rojas S Terreros P 《Dalton transactions (Cambridge, England : 2003)》2005,(5):938-944
The reaction of [Rh(micro-Cl)(COD)]2 with 4,6-dimethyl-pyrimidinethiolate (Me2-pymt) and subsequent substitution of COD by CO yields [Rh(Me2-pymt)(CO)2]. The stacking pattern found in this compound is in contradiction with previously studied comparable square-planar complexes of type d8-[M(chelate)(monodentate)2] in which each ligand has different pi-acidic character. A theoretical study of the intermolecular interactions and conformation of the title compound has been carried out, combining semi-empirical band calculations on the real chains and ab initio(MP2 level) calculations on a model dimer. The combination of electronic and steric effects determines the rotation of the successive monomers and the deviation from linearity of the one-dimensional stacks. Its behaviour in solution is also special, developing a blue colour and forming micelles, when adding water to acetone solutions. 相似文献