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71.
72.
Yunan Cui Henryk Hudzik Hongwei Zhu 《Proceedings of the American Mathematical Society》1998,126(1):115-121
Maluta's coefficient of Musielak-Orlicz sequence spaces equipped with the Orlicz norm is calculated. A sufficient condition for the Schur property of these spaces is given.
73.
Istvá n Juhá sz Peter Nyikos Zoltá n Szentmikló ssy 《Proceedings of the American Mathematical Society》2005,133(9):2741-2750
We give restrictions on the cardinality of compact Hausdorff homogeneous spaces that do not use other cardinal invariants, but rather covering and separation properties. In particular, we show that it is consistent that every hereditarily normal homogeneous compactum is of cardinality . We introduce property wD(), intermediate between the properties of being weakly -collectionwise Hausdorff and strongly -collectionwise Hausdorff, and show that if is a compact Hausdorff homogeneous space in which every subspace has property wD( ), then is countably tight and hence of cardinality . As a corollary, it is consistent that such a space is first countable and hence of cardinality . A number of related results are shown and open problems presented.
74.
Peter Hall 《Journal of multivariate analysis》1982,12(3):432-449
We compare the merits of two orthogonal series methods of estimating a density and its derivatives on a compact interval—those based on Legendre polynomials, and on trigonometric functions. By examining the rates of convergence of their mean square errors we show that the Legendre polynomial estimators are superior in many respects. However, Legendre polynomial series can be more difficult to construct than trigonometric series, and to overcome this difficulty we show how to modify trigonometric series estimators to make them more competitive. 相似文献
75.
Jaap F. Vente Steven McIntosh Wim G. Haije Henny J. M. Bouwmeester 《Journal of Solid State Electrochemistry》2006,10(8):581-588
The present paper discusses the oxygen transport properties, oxygen stoichiometry, phase stability, and chemical and mechanical
stability of the perovskites (BSCF) and (SCF) for air separation applications. The low oxygen conductive brownmillerite phase in SCF is characterized using in-situ
neutron diffraction, thermographic analysis and temperature programmed desorption but this phase is not present for BSCF under
the conditions studied. Although both materials show oxygen fluxes well above 10 ml/cm2·min at T=1,273 K and pO2=1 bar for self-supporting, 200 μm-thick membranes, BSCF is preferred as a membrane material due to its phase stability. However,
BSCF’s long-term stable performance remains to be confirmed. The deviation from ideal oxygen stoichiometry for both materials
is high: δ>0.6. The thermal expansion coefficients of BSCF and SCF are 24×10−6 and 30×10−6 K−1, respectively, as determined from neutron diffraction data. The phenomenon of kinetic demixing has been observed at pO2<10−5 bar, resulting in roughening of the surface and enrichment with alkaline earth metals. Stress–strain curves were determined
and indicated creep behavior that induces undesired ductility at T=1,073 K for SCF. Remedies for mechanical and chemical instabilities are discussed. 相似文献
76.
Chun Shen 《Mathematical Methods in the Applied Sciences》2020,43(6):3673-3688
The formation of vacuum state and delta shock wave are observed and studied in the limits of Riemann solutions for the one-dimensional isentropic drift-flux model of compressible two-phase flows by letting the pressure in the mixture momentum equation tend to zero. It is shown that the Riemann solution containing two rarefaction waves and one contact discontinuity turns out to be the solution containing two contact discontinuities with the vacuum state between them in the limiting situation. By comparison, it is also proved rigorously in the sense of distributions that the Riemann solution containing two shock waves and one contact discontinuity converges to a delta shock wave solution under this vanishing pressure limit. 相似文献
77.
Durdimurod Kalandarovich Durdiev Askar Ahmadovich Rahmonov 《Mathematical Methods in the Applied Sciences》2020,43(15):8776-8796
We consider a system of hyperbolic integro-differential equations of SH waves in a visco-elastic porous medium. In this work, it is assumed that the visco-elastic porous medium has weakly horizontally inhomogeneity. The direct problem is the initial-boundary problem: the initial data is equal to zero, and the Neumann-type boundary condition is specified at the half-plane boundary and is an impulse function. As additional information, the oscillation mode of the half-plane line is given. It is assumed that the unknown kernel has the form K(x,t)=K0(t)+ϵxK1(t)+…, where ϵ is a small parameter. In this work, we construct a method for finding K0,K1 up to a correction of the order of O(ϵ2). 相似文献
78.
Meina Sun 《Mathematical Methods in the Applied Sciences》2020,43(2):682-697
The solutions to the Riemann problem for a nonsymmetric system of Keyfitz-Kranzer type are constructed explicitly when the initial data are located in the quarter phase plane. In particular, some singular hyperbolic waves are discovered when one of the Riemann initial data is located on the boundary of the quarter phase plane, such as the delta shock wave and some composite waves in which the contact discontinuity coincides with the shock wave or the wave back of rarefaction wave. The double Riemann problem for this system with three piecewise constant states is also considered when the delta shock wave is involved. Furthermore, the global solutions to the double Riemann problem are constructed through studying the interaction between the delta shock wave and the other elementary waves by using the method of characteristics. Some interesting nonlinear phenomena are discovered during the process of constructing solutions; for example, a delta shock wave is decomposed into a delta contact discontinuity and a shock wave. 相似文献
79.
This paper is concerned with the limit relations from the Euler equations of one‐dimensional compressible fluid flow and the magnetohydrodynamics equations to the simplified transport equations, where the δ‐shock waves occur in their Riemann solutions of the latter two equations. The objective is to prove that the Riemann solutions of the perturbed equations coming from the one‐dimensional simplified Euler equations and the magnetohydrodynamics equations converge to the corresponding Riemann solutions of the simplified transport equations as the perturbation parameterx ε tends to zero. Furthermore, the result can also be generalized to more general situations. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
80.
We compare 13 different a posteriori error estimators for the Poisson problem with lowest-order finite element discretization. Residual-based error estimators compete with a wide range of averaging estimators and estimators based on local problems. Among our five benchmark problems we also look on two examples with discontinuous isotropic diffusion and their impact on the performance of the estimators. (Supported by DFG Research Center MATHEON.) 相似文献