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71.
Marina–Aura Dariescu Ciprian Dariescu 《International Journal of Theoretical Physics》2018,57(3):652-663
For the spatially open Friedmann–Robertson–Walker (FRW) Universe with stiff matter and radiation as non-interacting matter sources, the scale function coming from the integration of the Friedmann equation is expressed in terms of elliptic integrals. For a negative cosmological constant, we identify the allowed ranges for the model’s parameters. Within the quantum analysis, the Wheeler–De Witt (WDW) equation turns into a modified Morse equation whose solutions are Mathieu and Heun functions. 相似文献
72.
Magdalena A. ZaŁuska–Kotur Filip Krzyżewski StanisŁaw Krukowski 《Journal of Crystal Growth》2012,343(1):138-144
Step meandering during the growth of gallium nitride crystal is studied on using kinetic Monte Carlo method. Cause of instability is identified to be the particle advection caused by the step flow. Growth process is conducted in N-rich conditions and GaN(0001) surface kinetics is modeled by setting jump probabilities for Ga atoms adsorbed at the surface. We show that at low enough temperatures and relatively high external particle fluxes periodic regular pattern of meanders is created with its wavelength inversely proportional to the particle flux. An increase of the meander amplitude saturates after some period and further crystal grow is stationary, creating “finger-like” structure. For medium fluxes regular structure of meanders builds up for low or zero value of Schwoebel barrier. For higher fluxes wavelengths of meanders become shorter than the terrace width and they start to grow independently and finally transfer the surface to a rough structure. For very low fluxes or at relatively high temperatures steps move steadily remaining their initial shapes of straight, parallel lines. 相似文献
73.
D. Gopi R. Saraswathy G. Athithya L. Kavitha Jeong‐Heo Bae Dae–Kyeong Kim 《Surface and interface analysis : SIA》2012,44(10):1331-1337
In this paper, we have reported the anti‐corrosion performance of ceria / poly (indole‐co‐pyrrole) (Ce/(poly(In‐co‐Py)) bilayer coating on low nickel stainless steel (LN SS). Electrochemical polymerization of (poly (In‐co‐Py)) was achieved on ceria‐coated LN SS (CeO2/LN SS) in acetonitrile medium containing LiClO4 (ACN‐LiClO4) by cyclic voltammetric technique. The coatings were characterized by analytical techniques like Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive analysis of X‐ray, respectively. The mechanical behavior of the coatings was studied using peel test, hardness and wear resistance tests. The corrosion defensive performance of this bilayer coating on LN SS was investigated using electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy in 0.5 M H2SO4. These results show that the bilayer coating on LN SS lowered the permeability of corrosive ions present in the acidic medium and thus acts as a barrier against the attack of corrosive environment. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
74.
A new numerical scheme (which combines FEM, FVM and BEM methods) for solving thermohydrodynamic lubrication transient problems with cavitation is described. The algorithm is then applied to study the stability of a journal-bearing system. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
75.
Brandon Carter Richard A. Battye Jean–Philippe Uzan 《Communications in Mathematical Physics》2003,235(2):289-311
The computation of long range linear self-interaction forces in string and higher dimensional brane models requires the evaluation
of the gradients of regularised values of divergent self-interaction potentials. It is shown that the appropriately regularised
gradient in directions orthogonal to the brane surface will always be obtainable simply by multiplying the regularised potential
components by just half the trace of the second fundamental tensor, except in the hypermembrane case for which the method
fails. Whatever the dimension of the background this result is valid provided the codimension is two (the hyperstring case)
or more, so it can be used for investigating brane-world scenarios with more than one extra space dimension.
Received: 15 April 2002 / Accepted: 23 October 2002 Published online: 25 February 2003
Communicated by H. Nicolai 相似文献
76.
Summary. In this paper, the regularized solutions of an ill–conditioned system of linear equations are computed for several values
of the regularization parameter . Then, these solutions are extrapolated at by various vector rational extrapolations techniques built for that purpose. These techniques are justified by an analysis
of the regularized solutions based on the singular value decomposition and the generalized singular value decomposition. Numerical
results illustrate the effectiveness of the procedures.
Received June 23, 1997 / Revised version received October 24, 1997 相似文献
77.
78.
Andrea Bierschneider–Jakobs 《Mathematische Semesterberichte》1998,45(2):221-241
Zusammenfassung. Der vorliegende Artikel beschreibt anhand einfacher Beispiele ein Verfahren, vorgegebene Zylinder oder Kegel durch ein weiteres
Fl?chenstück (Teil einer sog.Dupinschen Zyklide) glatt zu verbinden (Blending). Zur L?sung werden Laguerregeometrie und Bézierdarstellung von Kurven verwendet. Ziel des Artikels ist es, grundlegende Ideen aus aktueller Forschung und Anwendung klassischer Geometrie darzustellen.
Eingegangen am 07.01.1998 / Angenommen am 22.05.1998 相似文献
79.
We generalise results of Jackson concerning cyclic Hadamard designs admitting SL(2,2n) as a point transitive automorphism group. The generalisation concerns the designs of Gordon, Mills and Welch and we characterise these as designs admitting GM(m,qn) acting in a certain way. We also generalise a construction given by Maschietti, using hyperovals, of cyclic Hadamard designs, and characterise these amongst the designs of Gordon, Mills and Welch. 相似文献
80.
Hruška Branislav Osipov Armenak A. Osipova Leyla M. Chromčíková Mária Černá Andrea Liška Marek 《Journal of Thermal Analysis and Calorimetry》2018,133(1):429-433
Journal of Thermal Analysis and Calorimetry - The temperature dependence of Raman spectra of 25Na2O·75B2O3 melts recorded in the temperature range 321–1142 °C was studied... 相似文献