Results 1 to 10 of about 5,519,001 (64)
Ural Mathematical Journal, 2023 We consider a variant \(E_{n,k}(N;r,r;p,p)\) of the four-parameter Stechkin problem \(E_{n,k}(N;r,s;p,q)\) on the best approximation of differentiation operators of order \(k\) on the class of \(n\) times differentiable functions ...
Vitalii V. Arestov
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On Landau-Kolmogorov type inequalities for charges and their applications
Researches in Mathematics, 2023 In this article we prove sharp Landau-Kolmogorov type inequalities on a class of charges defined on Lebesgue measurable subsets of a cone in $\mathbb{R}^d$, $d\geqslant 1$, that are absolutely continuous with respect to the Lebesgue measure.
V.F. Babenko +3 more
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Effect of Rotation Speed and Flow Rate on Slip Factor in a Centrifugal Pump
Shock and Vibration, Volume 2021, Issue 1, 2021., 2021 This work analyzes the causes of the slip phenomenon in the impeller on the basis of the internal flow mechanism. Detailed optical measurements of the flow inside the rotation passages of a five‐bladed centrifugal pump impeller are obtained through particle image velocimetry (PIV).
Bo Chen +7 more
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ON THE BEST APPROXIMATION OF THE DIFFERENTIATION OPERATOR
Ural Mathematical Journal, 2015 In this paper we give a solution of the problem of the best approximation in the uniform norm of the differentiation operator of order k by bounded linear operators in the class of functions with the property that the Fourier transforms of their ...
Vitalii V. Arestov
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Journal of Function Spaces, Volume 2015, Issue 1, 2015., 2015 Authors define w∗ nearly dentable Banach space. Authors study Radon‐Nikodym property, approximative compactness and continuity metric projector operator in w∗ nearly dentable space. Moreover, authors obtain some examples of w∗ nearly dentable space in Orlicz function spaces.
Shaoqiang Shang, Yunan Cui, Ismat Beg
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Uniform Approximation of Periodical Functions by Trigonometric Sums of Special Type
International Scholarly Research Notices, Volume 2014, Issue 1, 2014., 2014 The approximation characteristics of trigonometric sums Un,pψ of special type on the class Cβ,∞ψ of (ψ, β)‐differentiable (in the sense of A. I. Stepanets) periodical functions are studied. Because of agreement between parameters of approximative sums and approximated classes, the solution of Kolmogorov‐Nikol’skii problem is obtained in a sufficiently ...
A. S. Serdyuk +3 more
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Weighted Hardy‐Type Inequalities in Variable Exponent Morrey‐Type Spaces
Journal of Function Spaces, Volume 2013, Issue 1, 2013., 2013 We study the p(·) → q(·) boundedness of weighted multidimensional Hardy‐type operators Hwα· and ℋwα· of variable order α(x), with radial weight w(|x|), from a variable exponent locally generalized Morrey space ℒp(·),φ(·)(ℝn, w) to another ℒq(·),ψ(·)(ℝn, w). The exponents are assumed to satisfy the decay condition at the origin and infinity.
Dag Lukkassen +4 more
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On the approximation by trigonometric polynomials in weighted Lorentz spaces
Journal of Function Spaces, Volume 8, Issue 1, Page 67-86, 2010., 2010 We obtain estimates of structural characteristics of 2π‐periodic functions by the best trigonometric approximations in weighted Lorentz spaces, and show that the order of generalized modulus of smoothness depends not only on the rate of the best approximation, but also on the metric of the spaces.
Vakhtang Kokilashvili +2 more
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Journal of Function Spaces, Volume 8, Issue 3, Page 215-244, 2010., 2010 We consider non‐standard Hölder spaces Hλ(⋅)(X) of functions f on a metric measure space (X, d, μ), whose Hölder exponent λ(x) is variable, depending on x ∈ X. We establish theorems on mapping properties of potential operators of variable order α(x), from such a variable exponent Hölder space with the exponent λ(x) to another one with a “better ...
Natasha Samko +3 more
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New Characterization for Nonlinear Weighted Best Simultaneous Approximation
International Journal of Mathematics and Mathematical Sciences, Volume 2009, Issue 1, 2009., 2009 This paper is concerned with the problem of a wide class of weighted best simultaneous approximation in normed linear spaces, and it establishes a new characterization result for the class of approximation by virtue of the notion of simultaneous regular point.
Xianfa Luo +3 more
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