鞅Hardy空间与Hardy-Orlicz空间的鞅变换

利用鞅变换,刻画了鞅Hardy空间与Hardy-Orlicz空间之间的相互关系:当p_Φ+∞时,证明了Hardy-Orlicz空间H_Φ~s中的鞅是Hardy空间H_1~s中的鞅变换;反之,H_1~s中的鞅也是H_Φ~s中的鞅变换.所得结果推广了已有文献中的相应结论.     

Operator-Valued Fourier Multipliers on Multi-dimensional Hardy Spaces

The author establishes operator-valued Fourier multiplier theorems on multi-dimensional Hardy spaces H ^p ($ \mathbb{T} $ \mathbb{T} ^d ;X), where 1 ≤ p < ∞, d ∈ ℕ, and X is an AUMD Banach space having the property (α). The sufficient condition on the multiplier is a Marcinkiewicz type condition of order 2 using Rademacher boundedness of sets of bounded linear operators. It is also shown that the assumption that X has the property (α) is necessary when d ≥ 2 even for scalar-valued multipliers. When the underlying Banach space does not have the property (α), a sufficient condition on the multiplier of Marcinkiewicz type of order 2 using a notion of d-Rademacher boundedness is also given.     

A Note on Spaces of Absolutely Convergent Fourier Transforms

Let \({\mathcal {F}}f\) be an abolutely convergent Fourier transform on the real line. We extend the following result of K. Karlander to \({\mathbf {R}^{n}}\) for \(n \ge 1\) : Any closed reflexive subspace \(\{ {\mathcal {F}}f \}\) of the space of continuous functions vanishing at infinity is of finite dimension.     

Nonlinear Fourier Transforms and the mKdV Equation in the Quarter Plane

The unified transform method introduced by Fokas can be used to analyze initial‐boundary value problems for integrable evolution equations. The method involves several steps, including the definition of spectral functions via nonlinear Fourier transforms and the formulation of a Riemann‐Hilbert problem. We provide a rigorous implementation of these steps in the case of the mKdV equation in the quarter plane under limited regularity and decay assumptions. We give detailed estimates for the relevant nonlinear Fourier transforms. Using the theory of L²‐RH problems, we consider the construction of quarter plane solutions which are C¹ in time and C³ in space.     

Convergence of Double Walsh-Fourier Series and Hardy Spaces

It is proved that the maximal operator of the Marczinkiewicz-Fejér meams of a double Walsh-Fourier series is bounded from the two-dimensional dyadic martingale Hardy space H _p to L _p (2/3<p<∞) and is of weak type (1,1). As a consequence we obtain that the Marczinkiewicz-Fejér means of a function f∈L ₁ converge a.e. to the function in question. Moreover, we prove that these means are uniformly bounded on H _p whenever 2/3<p<∞. Thus, in case f∈H _p , the Marczinkiewicz-Fejér means conv f in H _p norm. The same results are proved for the conjugate means, too.     

Convergence of Double Walsh-Fourier Series and Hardy Spaces

It is proved that the maximal operator of the Marczinkiewicz-Fejér meams of a double Walsh-Fourier series is bounded from the two-dimensional dyadic martingale Hardy space H _p to L _p (2/3<p<) and is of weak type (1,1). As a consequence we obtain that the Marczinkiewicz-Fejér means of a function fL ₁ converge a.e. to the function in question. Moreover, we prove that these means are uniformly bounded on H _p whenever 2/3<p<. Thus, in case fH _p , the Marczinkiewicz-Fejér means conv f in H _p norm. The same results are proved for the conjugate means, too.     

On Lebesgue Integrability of Fourier Transforms in Amalgam Spaces

Journal of Fourier Analysis and Applications - Let f be an element of the subspace $$(L^{q},l^{p})^{\alpha }({\mathbb {R}}^d)$$ ( $$1\le q \le \alpha \le p \le 2 $$ ) of the Wiener amalgam space...     

On the Riemann Summability of Fourier Integrals and Real Hardy Spaces

We consider the Riemann means of single and multiple Fourier integrals of functions belonging to L¹ or the real Hardy spaces defined on ℝⁿ, where n ≥ 1 is an integer. We prove that the maximal Riemann operator is bounded both from H¹(ℝ) into L¹(ℝ) and from L¹(ℝ) into weak –L¹(ℝ). We also prove that the double maximal Riemann operator is bounded from the hybrid Hardy spaces H^(1,0)(ℝIsup2), H^(0,1)(ℝ²⁾ into weak –L¹(ℝ²). Hence pointwise Riemann summability of Fourier integrals of functions in H^(1,0) ∪ H^(0,1)(ℝ²) follows almost everywhere.The maximal conjugate Riemann operators as well as the pointwise convergence of the conjugate Riemann means are also dealt with.     

Parametrized Area Integrals on Hardy Spaces and Weak Hardy Spaces

In this paper, the authors prove that if Ω satisfies a class of the integral Dini condition, then the parametrized area integral μΩ,S^ρ is a bounded operator from the Hardy space H1 （R^n） to L1 （R^n） and from the weak Hardy space H^1,∞ （R^n） to L^1,∞ （R^n）, respectively. As corollaries of the above results, it is shown that μΩ,S^ρ is also an operator of weak type These conclusions are substantial improvement and （1, 1） and of type （p,p） for 1 〈 p 〈 2, respectively extension of some known results.     

On Fourier Series on the Torus and Fourier Transforms

Mathematical Notes - The question of the representability of a continuous function on $$\mathbb R^d$$ in the form of the Fourier integral of a finite Borel complex-valued measure on $$\mathbb R^d$$...     

Heisenberg群上与Schrödinger算子相关的Riesz变换在Hardy空间上的有界性

令L=?ΔHn+V是Heisenberg群Hn上Schr?dinger算子,其中非负位势V属于逆H?lder类.该文用分子刻画与L相关的Hardy型空间HL^p(H^n),进而得到了与L相关的Riesz变换的HL^p-有界性.     

调和H~p空间和混合范数空间

设Ｄ是一具有Ｃ边界的有界区域．本文就Ｄ上的调和Ｈａｒｄｙ空间和调和混合范数空间,建立了若干互相之间的连续嵌入定理．     

Discrete Hardy Spaces

We study the boundary behavior of discrete monogenic functions, i.e. null-solutions of a discrete Dirac operator, in the upper and lower half space. Calculating the Fourier symbol of the boundary operator we construct the corresponding discrete Hilbert transforms, the projection operators arising from them, and discuss the notion of discrete Hardy spaces. Hereby, we focus on the 3D-case with the generalization to the n-dimensional case being straightforward.     

Convolution Hankel Transforms on the Zemanian Spaces

In this paper we investigate the convolution Hankel transforms on the Zemanian spaces of Hankel transformable functions and distributions. The convolution Hankel transform is defined on generalized functions by using the adjoint method. Our new definition includes as special cases other known definitions of the convolution Hankel transform of distributions. Finally we establish a distributional inversion formula for the transformation under consideration involving Bessel differential operators.     

Remarks on Herz-Type Hardy Spaces

Basic properties of the Herz-type Hardy spaces , such as the boundedness of singular integral operators and the fractional integration operators, atomic decomposition, dense subspaces, etc., are established in the full range 0 < q < ∞. Partly supported by the Grants-in-Aid for Scientific Research (A)(1)11304009, (B)(1)10440046, Japan Society for the Promotion of Science.     

Riesz Transforms Characterizations of Hardy Spaces $$H^1$$ for the Rational Dunkl Setting and Multidimensional Bessel Operators

We characterize the Hardy space \(H^1\) in the rational Dunkl setting associated with the reflection group \(\mathbb {Z}_2^n\) by means of special Riesz transforms. As a corollary we obtain Riesz transforms characterization of \(H^1\) for product of Bessel operators in \((0,\infty )^n\).     

Approximation by Θ-Means of Walsh—Fourier Series in Dyadic Hardy Spaces and Dyadic Homogeneous Banach Spaces

Analysis Mathematica - In this article we discuss the behaviour of Θ-means of Walsh—Fourier series of a function in dyadic Hardy spaces Hp and dyadic homogeneous Banach spaces X. Namely,...     

Variable Hardy Spaces on the Heisenberg Group

We consider Hardy spaces with variable exponents defined by grand maximal function on the Heisenberg group. Then we introduce some equivalent characterizations of variable Hardy spaces. By using atomic decomposition and molecular decomposition we get the boundedness of singular integral operators on variable Hardy spaces. We investigate the Littlewood-Paley characterization by virtue of the boundedness of singular integral operators.     

Fourier multipliers on the real Hardy spaces

We provide a variant of Hytönen’s embedding theorem, which allows us to extend and unify several sufficient conditions for a function to be a Fourier multiplier on the real Hardy spaces.