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21.
The rotating ion collectors of E.M. isotope separators offer interesting possibilities to produce thin. very extended and uniform mono-isotopic layers deposited on thin A1 backings. Such targets are needed for high resolution electron spectroscopy studies following neutron eapture reactions induced by high flux neutron beams. 相似文献
22.
Francesc Aràndiga Antonio Baeza Dionisio F. Yáñez 《Advances in Computational Mathematics》2013,39(2):289-309
Monotonicity-preserving approximation methods are used in numerous applications. These methods are expected to reconstruct a function from a discrete set of data preserving Monotonicity properties (i.e., the reconstructed function has to be monotone wherever the discrete data are). Most Monotonicity-preserving methods sacrifice accuracy in order to obtain Monotonicity. In this work we propose and analyze a Monotonicity-preserving Hermite interpolant that does not fully sacrifice accuracy. A key ingredient in the proposed technique is the approximation of derivatives using ENO (Essentially Non Oscillatory) and WENO (Weighted Essentially Non Oscillatory) interpolatory techniques. Then, an appropriate filtering process ensures the preservation of Monotonicity while maintaining, at the same time, the order of accuracy as high as possible. We perform several numerical experiments which confirm the properties of the proposed algorithms and compare them to other standard interpolatory approximation techniques. 相似文献
23.
Abo-el-nour Abd-alla Ivan Giorgio Luca Galantucci Abdelmonam M. Hamdan Dionisio Del Vescovo 《Continuum Mechanics and Thermodynamics》2016,28(1-2):67-84
In this paper, the well-established two-dimensional mathematical model for linear pyroelectric materials is employed to investigate the reflection of waves at the boundary between a vacuum and an elastic, transversely isotropic, pyroelectric material. A comparative study between the solutions of (a) classical thermoelasticity, (b) Cattaneo–Lord–Shulman theory and (c) Green–Lindsay theory equations, characterised by none, one and two relaxation times, respectively, is presented. Suitable boundary conditions are considered in order to determine the reflection coefficients when incident elasto–electro–thermal waves impinge the free interface. It is established that, in the quasi-electrostatic approximation, three different classes of waves: (1) two principally elastic waves, namely a quasi-longitudinal Primary (qP) wave and a quasi-transverse Secondary (qS) wave; and (2) a mainly thermal (qT) wave. The observed electrical effects are, on the other hand, a direct consequence of mechanical and thermal phenomena due to pyroelectric coupling. The computed reflection coefficients of plane qP waves are found to depend upon the angle of incidence, the elastic, electric and thermal parameters of the medium, as well as the thermal relaxation times. The special cases of normal and grazing incidence are also derived and discussed. Finally, the reflection coefficients are computed for cadmium selenide observing the influence of (1) the anisotropy of the material, (2) the electrical potential and (3) temperature variations and (4) the thermal relaxation times on the reflection coefficients. 相似文献
24.
Thibault F Corretja B Viel A Bermejo D Martínez RZ Bussery-Honvault B 《Physical chemistry chemical physics : PCCP》2008,10(35):5419-5428
In this work we present a theoretical and experimental study of the acetylene-hydrogen system. A potential surface considering rigid monomers has been obtained by ab initio quantum chemistry methods. This 4-dimensional potential is further employed to compute, using the close-coupling approach and the coupled-states approximation, pressure broadening coefficients of C(2)H(2) isotropic Raman Q lines over a temperature range of 77 to 2000 K. Experimental data for the acetylene nu(2) Raman lines broadened by molecular hydrogen are obtained using stimulated Raman spectroscopy. The comparison of theoretical values with experimental data at 143 K is promising. Approximations to increase the computational efficiency are proposed. 相似文献
25.
Hossein Hassani Andreia Dionisio Mansoureh Ghodsi 《Nonlinear Analysis: Real World Applications》2010,11(1):492-502
The daily closing prices of several stock market indices are examined to analyse whether noise reduction matters in measuring dependencies of the financial series. We consider the effect of noise reduction on the linear and nonlinear measure of dependencies. We also use singular spectrum analysis as a powerful method for filtering financial series. We compare the results with those obtained by ARMA and GARCH models as linear and nonlinear methods for filtering the series. We also examine the findings on an artificial data set namely the Hénon map. 相似文献
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28.
Scotto Juliana Marmisollé Waldemar A. Posadas Dionisio 《Journal of Solid State Electrochemistry》2019,23(7):1947-1965
Journal of Solid State Electrochemistry - In the present work, we review the occurrence of capacitive currents in conducting polymer and, particularly, in the electrochemical response of... 相似文献
29.
Dionisio Gallarati 《Annali di Matematica Pura ed Applicata》1955,38(1):225-251
Sunto Si studiano alcune questioni generali relative al contatto d'ordine assegnato di due ipersuperficie algebriche F e G dello
spazio Sr lungo una varietà & (r−2)-dimensionale, ottenendo fra l'altro una semplice condizione necessaria e sufficiente affinchè &, contata q volte, esaurisca
l'intersezione di F e G. In secondo luogo si considera il caso di due superficie algebriche immerse in una V
3
algebrica ed aventi un contatto semplice lungo una curva priva di punti multipli; ed in particolare, qualora V
3
sia lo spazio ordinario, si prova che certe condizioni segnalate daB. Segre come condizioni necessarie affinchè una data superficie F possa essere tangente ad un'altra superficie lungo un' assegnata
curva & (non singolare), sono anche sufficienti se l'ordine di F è inferiore a5. Infine si dà l'effettiva costruzione delle superficie circoscritte ad una superficie F d'ordine m=2, 3, 4, e si mostra come i metodi impiegati possano essere utilizzati anche quando si abbandoni l'ipotesi m<5. 相似文献
30.
Amat Sergio Levin David Ruiz-Álvarez Juan Trillo Juan C. Yáñez Dionisio F. 《Numerical Algorithms》2022,91(1):51-79
Numerical Algorithms - In many applications, it is useful to use piecewise polynomials that satisfy certain regularity conditions at the joint points. Cubic spline functions emerge as good... 相似文献