共查询到20条相似文献,搜索用时 406 毫秒
1.
In this paper, a modified tangential frequency filtering decomposition (MTFFD) preconditioner is proposed. The optimal order
of the modification and the optimal relaxation parameter is determined by Fourier analysis. With the choice of optimal order
of modification, the Fourier results show that the condition number of the preconditioned matrix is
O(h-\frac23){{\mathcal O}(h^{-\frac{2}{3}})}, and the spectrum distribution of the preconditioned matrix can be predicted by the Fourier results. The performance of MTFFD
preconditioner is compared with tangential frequency filtering (TFFD) preconditioner on a variety of large sparse matrices
arising from the discretization of PDEs with discontinuous coefficients. The numerical results show that the MTFFD preconditioner
is much more efficient than the TFFD preconditioner. 相似文献
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We investigate the relationship between the univalence of f and of h in the decomposition of a sense-preserving harmonic mapping defined in the unit disk D⊂C. Among other results, we determine the holomorphic univalent maps h for which there exists c>0 such that every harmonic mapping of the form with |g′|<c|h′| is univalent. The notion of a linearly connected domain appears in our study in a relevant way. 相似文献
4.
Huei-Li Lin 《Journal of Differential Equations》2006,230(2):614-633
In this paper, assume that h is nonnegative and ‖hL2‖>0, we prove that if ‖hL2‖ is sufficiently small, then there are at least three positive solutions of Eq. (1) in , where D is a C1,1 bounded domain in . 相似文献
5.
S.S. Volosivets 《Journal of Mathematical Analysis and Applications》2011,383(2):344-352
For functions f∈L1(R)∩C(R) with Fourier transforms in L1(R) we give necessary and sufficient conditions for f to belong to the generalized Lipschitz classes Hω,m and hω,m in terms of behavior of . 相似文献
6.
Melvyn B. Nathanson 《Journal of Number Theory》2009,129(6):1608-1621
The set of nonnegative integers is an asymptotic basis of order h if every sufficiently large integer can be represented as the sum of h elements of A. If an∼αnh for some real number α>0, then α is called an additive eigenvalue of order h. The additive spectrum of order h is the set N(h) consisting of all additive eigenvalues of order h. It is proved that there is a positive number ηh?1/h! such that N(h)=(0,ηh) or N(h)=(0,ηh]. The proof uses results about the construction of supersequences of sequences with prescribed asymptotic growth, and also about the asymptotics of rearrangements of infinite sequences. For example, it is proved that there does not exist a strictly increasing sequence of integers such that bn∼n2 and B contains a subsequence such that bnk∼k3. 相似文献
7.
Roberta Filippucci Marco Rigoli 《Journal of Mathematical Analysis and Applications》2009,356(2):689-2670
In this paper we give sufficient conditions for the nonexistence of nonnegative nontrivial entire weak solutions of p-Laplacian elliptic inequalities, with possibly singular weights and gradient terms, of the form , under the main request that h and are continuous on R+. We achieve our conclusions introducing a generalized version of the well-known Keller-Osserman condition. 相似文献
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The classical singular value decomposition for a matrix A∈Cm×n is a canonical form for A that also displays the eigenvalues of the Hermitian matrices AA∗ and A∗A. In this paper, we develop a corresponding decomposition for A that provides the Jordan canonical forms for the complex symmetric matrices and . More generally, we consider the matrix triple , where are invertible and either complex symmetric or complex skew-symmetric, and we provide a canonical form under transformations of the form , where X,Y are nonsingular. 相似文献
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Let Ed(x) denote the “Euler polynomial” x2+x+(1−d)/4 if and x2−d if . Set Ω(n) to be the number of prime factors (counting multiplicity) of the positive integer n. The Ono invariantOnod of is defined to be except when d=−1,−3 in which case Onod is defined to be 1. Finally, let hd=hk denote the class number of K. In 2002 J. Cohen and J. Sonn conjectured that hd=3⇔Onod=3 and is a prime. They verified that the conjecture is true for p<1.5×107. Moreover, they proved that the conjecture holds for p>1017 assuming the extended Riemann Hypothesis. In this paper, we show that the conjecture holds for p?2.5×1013 by the aid of computer. And using a result of Bach, we also proved that the conjecture holds for p>2.5×1013 assuming the extended Riemann Hypothesis. In conclusion, we proved the conjecture is true assuming the extended Riemann Hypothesis. 相似文献
12.
We show that in certain Prüfer domains, each nonzero ideal I can be factored as , where Iv is the divisorial closure of I and is a product of maximal ideals. This is always possible when the Prüfer domain is h-local, and in this case such factorizations have certain uniqueness properties. This leads to new characterizations of the h-local property in Prüfer domains. We also explore consequences of these factorizations and give illustrative examples. 相似文献
13.
In this paper, we give a lower bound exp(2.2 × 10~8 ) for those discriminants of real quadratic fields Q(√ d) with d= N~2-4 and h(d)=1. 相似文献
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Mirjana Djori? 《Journal of Mathematical Analysis and Applications》2009,356(1):237-241
Considering n-dimensional real submanifolds M of a complex space form which are CR submanifolds of CR dimension , we study the condition h(FX,Y)+h(X,FY)=0 on the structure tensor F naturally induced from the almost complex structure J of the ambient manifold and on the second fundamental form h of submanifolds M. 相似文献
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Guilong Gui 《Advances in Mathematics》2010,225(3):1248-1284
In this paper, we consider the stability to the global large solutions of 3-D incompressible Navier-Stokes equations in the anisotropic Sobolev spaces. In particular, we proved that for any , given a global large solution v∈C([0,∞);H0,s0(R3)∩L3(R3)) of (1.1) with and a divergence free vector satisfying for some sufficiently small constant depending on , v, and , (1.1) supplemented with initial data v(0)+w0 has a unique global solution in u∈C([0,∞);H0,s0(R3)) with ∇u∈L2(R+,H0,s0(R3)). Furthermore, uh is close enough to vh in C([0,∞);H0,s(R3)). 相似文献
18.
Yan Pautrat 《Journal of Functional Analysis》2004,208(1):163-193
We give a necessary and sufficient condition for the second quantization operator Γ(h) of a bounded operator h on , or for its differential second quantization operator λ(h), to have a representation as a quantum stochastic integral. This condition is exactly that h writes as the sum of a Hilbert-Schmidt operator and a multiplication operator. We then explore several extensions of this result. We also examine the famous counterexample due to Journé and Meyer and explain its representability defect. 相似文献
19.
Takeshi Miura Shizuo Miyajima 《Journal of Mathematical Analysis and Applications》2003,286(1):136-146
Let X be a complex Banach space and a continuous function. Let be the linear differential operator defined by Thu=u′+hu. We give a necessary and sufficient condition in order that the operator Th has the Hyers-Ulam stability. 相似文献