On maximal immediate extensions of valued fields

We study the maximal immediate extensions of valued fields whose residue fields are perfect and whose value groups are divisible by the residue characteristic if it is positive. In the case where there is such an extension which has finite transcendence degree we derive strong properties of the field and the extension and show that the maximal immediate extension is unique up to isomorphism, although these fields need not be Kaplansky fields. If the maximal immediate extension is an algebraic extension, we show that it is equal to the perfect hull and the completion of the field.     

Strong maximal operator and singular integral operators in weighted Morrey spaces on product domains

We introduce the Morrey spaces on product domains and extend the boundedness of strong maximal operator and singular integral operators on product domains to Morrey spaces.     

Short time existence for the elastic flow of clamped curves

We show well‐posedness of the elastic flow of open curves with clamped boundary conditions. To show short time existence we prove that the linearised problem has the property of maximal ‐regularity and use the contraction principle to obtain the solution. Moreover, we show analyticity of the solution and its analytic dependency on the initial curve. With the developed methods we also prove long time existence of the flow if the initial curve is close to an elastica.     

Uniform convergence of sine transforms of general monotone functions

We obtain necessary and sufficient conditions for the uniform convergence of sine integrals where g satisfies general monotonicity conditions. In contrast with the previous results on this topic, here we do not assume .     

Maximal ‐regularity for fractional differential equations on the line

We characterize the ‐maximal regularity of an abstract fractional differential equation with delay on the Lebesgue spaces. The method is based on the theory of operator‐valued Fourier multipliers and weighted Sobolev spaces on the line.     

关于Van Der Corput不等式双参数推广的改进

梳理了有关Van Der Corput不等式的研究成果与方法,并对Van Der Corput不等式的双参数推广作了进一步改进,建立了更强的推广式,它优于现有的相关结论.     

Vallée-Poussin算子逼近连续函数的最优估计

通过将Vallée-Poussin算子逼近连续函数的能力转化为对辅助数列{g(n)}的上确界的计算,首先利用数列单调有界定理证明辅助数列极限的存在性,之后借助夹逼准则求得辅助数列{g(n)}的极限,即数列{g(n)}的上确界,进而得到Vallée-Poussin算子逼近连续函数的最优估计常数.     

一类具交错扩散的互惠模型的共存解

研究了Dirichlet边界条件下具交错扩散的两种群互惠模型.采用上下解方法,结合Schauder不动点理论,给出了问题共存解存在的充分条件.进一步,利用单调迭代序列的方法构造出问题的共存解.结果表明,当交错扩散相对弱时,问题至少存在一共存解.     

无穷个m增生映射和逆强增生映射的隐式单调投影算法与p-Laplacian系统

首先在Hilbert空间中,设计了带误差项的隐式单调投影迭代算法,证明了迭代序列强收敛到无穷个非线性m增生映射与逆强增生映射和的公共零点的结论,将以往的相关研究成果从有限个映射的情形推广到无穷个;其次采用分裂法将一类p-Laplacian型抛物系统转化成算子方程的形式,证明了p-Laplacian型抛物系统非平凡解的存在性并建立了非平凡解与无穷个m增生映射与逆强增生映射和的公共零点的关系;最后构造了p-Laplacian型抛物系统非平凡解的迭代逼近序列,推广和补充了以往的相关研究成果.