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Wyszukujesz frazę "Alvarez, M." wg kryterium: Autor


Wyświetlanie 1-3 z 3
Tytuł:
Solutions for conservative nonlinear oscillators using an approximate method based on Chebyshev series expansion of the restoring force
Autorzy:
Beléndez, A.
Hernández, A.
Beléndez, T.
Pascual, C.
Alvarez, M.
Arribas, E.
Powiązania:
https://bibliotekanauki.pl/articles/1075577.pdf
Data publikacji:
2016-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.30.Hq
02.30.Mv
05.45.-a
Opis:
Approximate solutions for small and large amplitude oscillations of conservative systems with odd nonlinearity are obtained using a "cubication" method. In this procedure, the Chebyshev polynomial expansion is used to replace the nonlinear function by a third-order polynomial equation. The original second-order differential equation, which governs the dynamics of the system, is replaced by the Duffing equation, whose exact frequency and solution are expressed in terms of the complete elliptic integral of the first kind and the Jacobi elliptic function cn, respectively. Then, the exact solution for the Duffing equation is the approximate solution for the original nonlinear differential equation. The coefficients for the linear and cubic terms of the approximate Duffing equation - obtained by "cubication" of the original second-order differential equation - depend on the initial oscillation amplitude. Six examples of different types of common conservative nonlinear oscillators are analysed to illustrate this scheme. The results obtained using the cubication method are compared with those obtained using other approximate methods such as the harmonic, linearized and rational balance methods as well as the homotopy perturbation method. Comparison of the approximate frequencies and solutions with the exact ones shows good agreement.
Źródło:
Acta Physica Polonica A; 2016, 130, 3; 667-678
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
X-ray diffraction microstructural analysis of swelling by ethylene glycol in two reference clay minerals
Autorzy:
García Tomás, F.
Kojdecki, M.
Pardo, P.
Ibańez, R.
Álvarez Larena, A.
Bastida, J.
Powiązania:
https://bibliotekanauki.pl/articles/1152823.pdf
Data publikacji:
2016-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.37.Vj
61.72.Dd
Opis:
Kaolinite and montmorillonite are two clay minerals with different structures: dioctahedral 1:1 without layer charge and dioctahedral 2:1 with low layer charge. X-ray-diffraction microstructural analysis of two fractions of two reference clays (with kaolinite or montmorillonite) from the Clay Minerals Society Source Clay Repository were performed by the Voigt function method to provide microstructural data not available in the baseline studies of this Repository. A rough agreement was found between crystallite sizes determined from X-ray diffraction patterns and from images by field-emission scanning electron microscopy. In addition, the influence of swelling by ethylene-glycol on crystallite size was studied by the mentioned method. Two factors were found to affect the crystallite size variation in ethylene-glycol-treated clay minerals: (i) the increase of the unit cell in [001] direction due to the interlayer absorption of ethylene glycol molecules in the case of swelling minerals and (ii) the physisorption at the surfaces of the crystallites. Both effects operate in the case of montmorillonite, whereas just the latter one is expected in kaolinite.
Źródło:
Acta Physica Polonica A; 2016, 130, 4; 876-879
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetocaloric Effect in Nanostructured $Pr_2Fe_{17}$ and $Nd_2Fe_{17}$ Synthesized by High-Energy Ball-Milling
Autorzy:
Alvarez, P.
Sánchez-Marcos, J.
Sanchez Llamazares, J.
Franco, V.
Reiffers, M.
Blanco, J.
Gorria, P.
Powiązania:
https://bibliotekanauki.pl/articles/1534200.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.05.cp
75.50.Tt
75.30.Kz
Opis:
Nanocrystalline $Pr_2Fe_{17}$ and $Nd_2Fe_{17}$ powders with rhombohedral $Th_2Zn_{17}$-type crystal structure and average particle sizes around 20 nm have been obtained by high-energy ball milling. While the bulk alloys show a well-defined and sharp drop in the low-field magnetization curve at the Curie temperature, $T_{C}$ = 285 K (Pr) and 335 K (Nd), the ball-milled samples exhibit a substantial broadening of the ferro-to-paramagnetic transition due to a considerable augmentation of the disordered inter-grain boundaries. The latter results in an increase of more than 25% in the values of the full width at half maximum of the temperature dependence of the magnetic entropy change maintaining almost unchanged the relative cooling power.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 867-869
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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