λ-Central BMO estimates for multilinear commutators of fractional integrals

The author establishes λ-central BMO estimates for commutators of multilinear fractional integral operators on central Morrey spaces.     

Absolutely convergent Fourier series and function classes

We study the smoothness property of a function f with absolutely convergent Fourier series, and give best possible sufficient conditions in terms of its Fourier coefficients to ensure that f belongs either to one of the Lipschitz classes Lip(α) and lip(α) for some 0<α?1, or to one of the Zygmund classes Λ_∗(1) and λ_∗(1). Our theorems generalize some of those by Boas [R.P. Boas Jr., Fourier series with positive coefficients, J. Math. Anal. Appl. 17 (1967) 463-483] and one by Németh [J. Németh, Fourier series with positive coefficients and generalized Lipschitz classes, Acta Sci. Math. (Szeged) 54 (1990) 291-304]. We also prove a localized version of a theorem by Paley [R.E.A.C. Paley, On Fourier series with positive coefficients, J. London Math. Soc. 7 (1932) 205-208] on the existence and continuity of the derivative of f.     

Distance-two labellings of Hamming graphs

Let j≥k≥0 be integers. An ?-L(j,k)-labelling of a graph G=(V,E) is a mapping ?:V→{0,1,2,…,?} such that |?(u)−?(v)|≥j if u,v are adjacent and |?(u)−?(v)|≥k if they are distance two apart. Let λ_j,k(G) be the smallest integer ? such that G admits an ?-L(j,k)-labelling. Define to be the smallest ? if G admits an ?-L(j,k)-labelling with ?(V)={0,1,2,…,?} and ∞ otherwise. An ?-cyclic L(j,k)-labelling is a mapping ?:V→Z_? such that |?(u)−?(v)|_?≥j if u,v are adjacent and |?(u)−?(v)|_?≥k if they are distance two apart, where |x|_?=min{x,?−x} for x between 0 and ?. Let σ_j,k(G) be the smallest ?−1 of such a labelling, and define similarly to . We determine λ_2,0, , σ_2,0 and for all Hamming graphs K_q1□K_q2□?□K_qd (d≥2, q₁≥q₂≥?≥q_d≥2) and give optimal labellings, with the only exception being for q≥4. We also prove the following “sandwich theorem”: If q₁ is sufficiently large then for any graph G between K_q1□K_q2 and K_q1□K_q2□?□K_qd, and moreover we give a labelling which is optimal for these eight invariants simultaneously.     

一般投影线性群PGL(2,q)和4-(q+1,5,λ)设计

本文主要考虑了一般投影线性群PGL(2,q)区传递作用下的4-(q+1,5,λ)设计的存在性问题。经讨论知λ的可能值是4。     

Branching one-dimensional periodic diffusion processes

Let X be a nonsingular conservative one-dimensional periodic diffusion process, λ₀ its principal eigenvalue and X a binary splitting branching diffusion process with nonbranching part X. For each α > λ₀ we have two positive martingales Wⁱ_t(α), i = 1, 2, of X attached to the two positive α-harmonic functions of X. The main purpose of this paper is to show that their limit random variables are positive for all α? (λ₀, α_i), where α_i are some constants greater than λ₀.     

关于一类新型权函数Aλ3γ(λ1,λ2;E)的性质

Aλ3γ (λ1,λ2;E)-权函数是一类广义的权函数,可视为许多经典权函数的推广.文中给出了关于Aλ3γ(λ1,λ2;E)-权的和与积的运算性质,并进而证明了Aλ3γ(λ1,λ2;E)-权函数的两个充要条件.     

Hilbert's double series theorem extended to the case of non-homogeneous kernels

Sharp version of celebrated Hilbert's double series theorem is given in the case of non-homogeneous kernel. The main mathematical tools are: the integral representation of Mathieu's (a,λ)-series, the Hölder inequality and an extension of the double series theorem by Yang.     

Weighted estimates for parametrized Littlewood-Paley operators

In this paper, we obtain some boundedness on the weighted Lebesgue spaces and the weighted Hardy spaces for the parametrized Littlewood-Paley operators with the kernel Ω satisfying the logarithmic type Lipschitz conditions.     

非均匀传输线型谐振腔的研究

 分析了周期性电容盘片加载的同轴线的传输特性,并将其应用于四分之一波长线谐振腔,利用传输线理论和数值模拟两种方法分析了这种腔体的谐振特性,得到了谐振频率、Q值与盘片半径、盘片个数间的关系,并论证了这种方法在减小腔体尺寸方面的可行性及在一台质子回旋加速器腔体中的应用。