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101.
Stere?Ianu?Email author Renzo?Mazzocco Gabriel?Eduard?V?lcu 《Mediterranean Journal of Mathematics》2006,3(3-4):581-592
The main purpose of this paper is to give basic properties of real lightlike hypersurfaces of paraquaternionic manifold and
to prove the nonexistence of real lightlike hypersurfaces in paraquaternionic space forms under some conditions.
Dedicated to the memory of Professor Aldo Cossu 相似文献
102.
In this paper, a new proof for the estimates of Calderón-Zygmund type singular integrals will be presented.
Received: 30 October 2005 相似文献
103.
We will give some conditions for Sobolev spaces on bounded Lipschitz domains to admit only trivial isometries. 相似文献
104.
Xiang Ma 《manuscripta mathematica》2006,120(2):163-179
Using moving frame method, we study the Möbius geometry of a pair of conformally immersed surfaces in
. Two new invariants θ and ρ associated with them arise naturally as well as the notion of touch and co-touch. As an application, adjoint transform is defined for any Willmore surface in
. It always exists locally, hence generalizes known duality theorems of Willmore surfaces. Finally we characterize a pair of adjoint Willmore surfaces in terms of harmonic map. 相似文献
105.
Hany M. El-Hosseiny 《Potential Analysis》2006,25(2):131-145
We prove general boundary limit theorems of abelian type for quotients of functions defined in the half space . The functions considered are defined as convolutions of a kernel with Borel measures defined on the boundary . Our theorems are of the form
where the approach to the limit in question is either non-tangential (Theorems 3.4 and 3.3), or radial (Theorem 3.2). The key feature is the relation of subordination in the sense of Bochner between the two kernels and . Our results generalize many known ones, such as the abelian theorem of Doob and that of Armitage for relative harmonic functions, and the results of Watson and Doob for Parabolic functions. 相似文献
106.
Igor Shparlinski 《Linear algebra and its applications》2006,414(1):378-382
We give an explicit construction of circulant graphs of very high energy. This construction is based on Gauss sums. We also show the Littlewood conjecture can be used to establish new result for a certain class of circulant graphs. 相似文献
107.
Fractal Gaussian models have been widely used to represent the singular behavior of phenomena arising in different applied fields; for example, fractional Brownian motion and fractional Gaussian noise are considered as monofractal models in subsurface hydrology and geophysical studies Mandelbrot [The Fractal Geometry of Nature, Freeman Press, San Francisco, 1982 [13]]. In this paper, we address the problem of least-squares linear estimation of an intrinsic fractal input random field from the observation of an output random field affected by fractal noise (see Angulo et al. [Estimation and filtering of fractional generalised random fields, J. Austral. Math. Soc. A 69 (2000) 1-26 [2]], Ruiz-Medina et al. [Fractional generalized random fields on bounded domains, Stochastic Anal. Appl. 21 (2003a) 465-492], Ruiz-Medina et al. [Fractional-order regularization and wavelet approximation to the inverse estimation problem for random fields, J. Multivariate Anal. 85 (2003b) 192-216]. Conditions on the fractality order of the additive noise are studied to obtain a bounded inversion of the associated Wiener-Hopf equation. A stable solution is then obtained in terms of orthogonal bases of the reproducing kernel Hilbert spaces associated with the random fields involved. Such bases are constructed from orthonormal wavelet bases (see Angulo and Ruiz-Medina [Multiresolution approximation to the stochastic inverse problem, Adv. in Appl. Probab. 31 (1999) 1039-1057], Angulo et al. [Wavelet-based orthogonal expansions of fractional generalized random fields on bounded domains, Theoret. Probab. Math. Stat. (2004), in press]). A simulation study is carried out to illustrate the influence of the fractality orders of the output random field and the fractal additive noise on the stability of the solution derived. 相似文献
108.
Christophe Cuny 《Journal of multivariate analysis》2006,97(8):1842-1869
Let (Xm,n)(m,n)∈Z2 be a Cp-valued wide sense stationary process. We study the prediction theory of such processes according to different total orders on Z2. In the case of a “rational order”, we give the spectral distribution of the resulting evanescent component and prove that for two different rational orders, the resulting evanescent components are mutually orthogonal. 相似文献
109.
The process of casting occupies an important place in the metallurgical industry, and the entire world of the metal user. In the past, the ingot casting–rolling (slabbing, blooming, or billeting) process was commonly used. The continuous casting process has largely replaced this earlier method because of the inherent advantages of energy savings, enhanced productivity, higher yield and reduced costs. However, continuous casting process is not without of its problems. Considerable effort has been made by many researches to establish adequate design, operation and maintenance of continuous casting machine to ensure metallurgical quality of the final product. One of the most severe defects in continuous casting products is concerned with the cracks provoked by improper design of the spray cooling system. The aim of this work is to develop a two dimensional heat transfer model based on the finite difference method in order to calculate the strand temperatures and the solid shell profile along the machine. An Artificial Intelligence heuristic search procedure interacts with the numerical model to determine the improved cooling conditions for the sprays zones of a real continuous caster for the production of quality billets. 相似文献
110.