An inverse spectral problem for a nonsymmetric differential operator: Reconstruction of eigenvalue problem

In this paper, an algorithm is established to reconstruct an eigenvalue problem from the given data satisfying certain conditions. These conditions are proved to be not only necessary but also sufficient for the given data to coincide with the spectral characteristics corresponding to the reconstructed eigenvalue problem.     

An inverse spectral problem for a nonnormal first order differential operator

We study the eigenvalues of two restrictions ofB _x +P whereB is the two-by-two matrix that is zero on the diagonal and one off the diagonal andP is a two-by-two matrix of Lipschitz functions on the unit interval. We establish asymptotic forms for their eigenvalues and associated root vectors and demonstrate that these root vectors constitute a Riesz basis inL ²(0, 1)². We show that our forward analysis makes rigorous the attack on the associated inverse problem by M. Yamamoto,Inverse spectral problem for systems of ordinary differential equations of first order, I, J. Fac. Sci. Univ. Tokyo, Sect. 1A, Math. 35, 1988, pp. 519–546. We apply these results to the recovery of the line resistance and leakage conductance of a nonuniform transmission line.Supported by NSF grant DMS-9258312.     

Inverse spectral problem for differential operator pencils on noncompact spatial networks

We study boundary value problems on noncompact cycle-free graphs (i.e., trees) for second-order ordinary differential equations with a nonlinear dependence on the spectral parameter. We establish properties of the spectrum and analyze the inverse problem of reconstructing the coefficients of a differential equation on the basis of the so-called Weyl functions. For this inverse problem, we prove a uniqueness theorem and obtain a procedure for constructing the solution by the method of spectral mapping.     

具有线性微分算子的分数阶微分方程积分边值问题

研究一类具有分数阶线性微分算子的非线性微分方程积分边值问题解的存在性与唯一性.利用Schauder不动点定理及压缩映射原理,建立并证明了边值问题解的存在性定理和唯一性定理,并给出两个例子以说明所得结论.     

Correctness of the Cauchy problem for trinomial higher-order operator differential equations

Criteria are established for the correctness of the Cauchy problem for the equationsy ⁽²ⁿ⁾+Ay ⁽ⁿ⁾++By=0,t [0, ), wheren > 1;A andB are arbitrary commuting self-adjoint operators in a Hilbert space. Forn=2, the criterion is illustrated by the example of the equation describing the dynamics of an exponentially stratified rotating compressible fluid.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 45, No. 5, pp. 704–714, May, 1993.     

Nonlinear spectral problem for a Hamiltonian system of differential equations with redundant conditions

We consider a nonlinear spectral problem for a self-adjoint Hamiltonian system of differential equations. The boundary conditions correspond to a self-adjoint problem. It is assumed that the input data (the matrix of the system and the matrices of the boundary conditions) satisfy certain conditions of monotonicity with respect to the spectral parameter. In addition to the main boundary conditions, a redundant nonlocal condition given by a Stieltjes integral is imposed on the solution. For the nontrivial solvability of the over-determined problem thus obtained, the original problem is replaced by an auxiliary problem that is consistent with the entire set of conditions. This auxiliary problem is obtained from the original one by allowing a discrepancy of a specific form. We study the resulting problem and give a numerical method for its solution.     

Associated functions of a nonlinear spectral problem for a system of ordinary differential equations

We study the notion of associated functions of a nonlinear spectral problem for a linear system of ordinary differential equations supplemented with nonlocal conditions given by a Stieltjes integral. We establish the relationship of this problem with the corresponding problem in a finite-dimensional linear space. We consider a numerical method for finding associated functions and justify its stability.     

Nonlinear spectral problem for a singular system of ordinary differential equations with a nonlocal condition

We consider a nonlinear spectral problem for a system of ordinary differential equations defined on an unbounded half-line and supplemented with a nonlocal condition specified by a Stieltjes integral. We suggest a numerically stable method for finding the number of eigenvalues lying in a given bounded domain of the complex plane and for the computation of these eigenvalues and the corresponding eigenfunctions. Our approach uses a simpler (with uncoupled boundary conditions) auxiliary boundary value problem for the same equation.     

Inverse spectral reconstruction problem for the convolution operator perturbed by a one-dimensional operator

We consider a one-dimensional perturbation of the convolution operator. We study the inverse reconstruction problem for the convolution component using the characteristic numbers under the assumption that the perturbation summand is known a priori. The problem is reduced to the solution of the so-called basic nonlinear integral equation with singularity. We prove the global solvability of this nonlinear equation. On the basis of these results, we prove a uniqueness theorem and obtain necessary and sufficient conditions for the solvability of the inverse problem.     

An operator method of solving the Cauchy problem for a homogeneous system of partial differential equations

On the basis of a generalized separation-of-variables method we propose an operator method of constructing the solution of the Cauchy problem for a homogeneous system of partial differential equations of first order with respect to time and of infinite order with respect to the spatial variables. Translated fromMatematichni Metody i Fiziko-Mekhanichni Polya, Vol. 38, 1995.     

On the correct solvability of the Dirichlet problem for operator differential equations in a Banach space

We investigate the structure of solutions of an equation y″(t) = By(t), where B is a weakly positive operator in a Banach space , on the interval (0, ∞) and establish the existence of their limit values as t → 0 in a broader locally convex space containing as a dense set. The analyticity of these solutions on (0, ∞) is proved and their behavior at infinity is studied. We give conditions for the correct solvability of the Dirichlet problem for this equation and substantiate the applicability of power series to the determination of its approximate solutions. __________ Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 58, No. 11, pp. 1462–1476, November, 2006.     

带p-Laplacian算子的分数阶微分方程非局部边值问题解的存在性

利用经典的Schaefer不动点定理,研究了一类带有p-Laplacian算子的非线性分数阶微分方程非局部边值问题,在适当的假设条件下,得到了解的存在性结果.并举例说明结果的应用.     

A certain ill-posed Cauchy problem for first-order and second-order differential equations with operator coefficients

Translated from Sibirskii Matematicheskii, Vol. 35, No. 3, pp. 702–706, May–June, 1994.