二项自伴向量微分算子的本质谱

首先利用算子比较的方法,研究了二项自伴向量微分算子的本质谱,得到了这类微分算子的本质谱分布范围;然后利用算子分解定理,得到了这类算子谱的离散性的一个充分条件;最后得到了Sturm-Liouville算子和Schr?dinger算子的本质谱范围,以及这两类算子谱的离散性的一个充分条件.     

一类具指数系数的对称微分算子谱的离散性

研究了具指数函数系数的2n阶实系数微分算式生成的对称微分算子,利用算子的直和分解法及不等式估计得到此类微分算子谱是离散的充分条件.     

两类自共轭微分算子谱的离散性

研究了两类对称微分算式生成的微分算子的谱的离散性.首先给出了一类三项四阶自共轭微分算子谱的离散性的充要条件.进而讨论了一类高阶自共轭微分算子的谱的离散性.     

一类高阶微分算子谱的离散性的充分必要条件

利用算子直和分解的方法和二次型比较的方法,研究一类2n(n≥1)阶微分算子谱的离散性,得到该微分算子的谱是离散的几个充分必要条件.     

2n阶自伴向量微分算子的谱是离散的充分条件

把纯量微分算子谱的离散性的结论推广到向量微分算子情形,从而得到了这类微分算子的谱是离散的充分条件.     

Euler微分算子谱是离散的充分必要条件

本文在研究一类高阶微分算子谱的离散性的基础上研究了2n阶实系数Euler微分算式生成的对称微分算子,进一步完善了自伴Euler微分算子的谱是离散的充分必要条件.     

L2[α,∞)上高阶Sturm-Liouville算子下半有界性与谱

采用泛函分析与不等式渐近估计的方法,根据微分算子系数的特点,研究了高阶Sturm-Liouville微分算子下半有界性并得到其为下半有界的一些判定准则,同时给出了其下界的估计.这些结果对研究微分算子的谱是有益的.     

L^2[a,\infty)上高阶 Sturm-Liouville 算子下半有界性与谱

采用泛函分析与不等式渐近估计的方法,根据微分算子系数的特点,研究了高阶Sturm-Liouville微分算子下半有界性并得到其为下半有界的一些判定准则,同时给出了其下界的估计.这些结果对研究微分算子的谱是有益的.     

2n阶J-自伴向量微分算子的本质谱

利用算子直和分解的方法研究了2n阶J-自伴向量微分算子的本质谱,得到了这类算子的本质谱的分布范围.     

一类具欧指积系数微分算子谱的离散性(英文)

利用算子直和分解的方法和二次型估计的方法,研究了一类具欧指积系数微分算子谱的离散性,得到了其谱是离散的一些充分条件.     

一类具有离散谱的对称微分算子

研究了一类2n-阶线性微分算子在加权Hilbert空间中的谱.通过对加权Sobolev空间H     

Spectral theory of higher order difference operators

The spectral theory of higher order difference operators is studied by means of asymptotic summation, thereby extending many results of differential operators to the discrete setting. The spectra of degenerate fourth-order operators are also investigated. The results are then compared with those of corresponding differential operators. Even though there are many similarities between both classes of operators, the spectral results may be quite distinct.     

Spectral analysis of higher order differential operators with unbounded coefficients

Higher even order linear differential operators with unbounded coefficients are studied. For these operators the eigenvalues of the characteristic polynomials fall into distinct classes or clusters. Consequently the spectral properties, deficiency indices and spectra, of the underlying differential operators are superpositions of the contributions from the individual clusters. These results are based on a quantitative improvement of Levinson's Theorem. Our methods will also be applicable to other classes of linear differential operators.     

On invertible contractions of quotients generated by a differential expression and by a nonnegative operator function

In the present paper, we describe invertible contractions of the maximal quotient generated by a differential expression with bounded operator coefficients and by a nonnegative operator function. We show that the operators inverse to such contractions are integral operators and prove a criterion for such operators to be holomorphic. Using the results obtained, we describe the generalized resolvents of symmetric quotients.     

一类函数空间上偏微分算子有界性和紧性的刻画(英文)

本文研究了一类具有再生核的多复变量函数空间上偏微分算子的有界性和紧性.利用算子理论的方法,获得了偏微分算子是有界的和紧的充分必要条件,推广了文献[1]中的结果.     

Quadruple and octuple layer potentials in two dimensions I: Analytical apparatus

A detailed analysis is presented of all pseudo-differential operators of orders up to 2 encountered in classical potential theory in two dimensions. Each of the operators under investigation turns out to be a sum of one or more of standard operators (second derivative, derivative of the Hilbert transform, etc.), and an integral operator with smooth kernel. This classification leads to an extremely simple analysis of spectra of such operators, and simplifies the design of procedures for their numerical evaluation. In a sequel to this paper, the obtained apparatus will be used to construct stable discretizations of arbitrarily high order for a variety of boundary value problems for elliptic partial differential equations.     

Global Homotopy Formulas on <Emphasis Type="Italic">q</Emphasis>-Concave <Emphasis Type="Italic">CR</Emphasis> Manifolds for Large Degrees

Using functional analysis and a Friedrichs approximation lemma for first order differential operators, we derive a global homotopy formula in large degrees for the tangential Cauchy-Riemann operator from local homotopy formulas without loss of regularity.     

On spectra of some linear elliptic differential operators

In the study of boundary-value problems, we often need information on the spectra of the corresponding differential operators. In this paper, we discuss the location of spectra of linear elliptic differential operators in ℝⁿ, n ∈ ℕ.Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 9, Suzdal Conference-3, 2003.     

Fixed points of generalized e-concave (generalized e-convex) operators and their applications

In this paper, we present the definitions of generalized e-concave operators and generalized e-convex operators, which are the generalizations of e-concave operators and e-convex operators, respectively. Without compactness or continuity assumption of generalized e-concave operators and generalized e-convex operators, we have proved the existence, uniqueness and monotone iterative techniques of their fixed points. Our results are even new to e-concave operators and e-convex operators. Finally, we apply the results to the singular boundary value problems for second order differential equations.