Integrability of Solutions of Nonlinear Elliptic Equations with Right-Hand Sides from Logarithmic Classes

We establish the existence of a weak solution to the Dirichlet problem belonging to a Sobolev space for nonlinear elliptic equations of second order with right-hand sides from a wide class of functions defined in terms of the logarithmic function.     

Envelope Solutions for Implicit Ordinary Differential Equations

In recent papers the numerical solution of implicit ordinarydifferential equations of the form f(x, y(x), y'(x))=0 has beendiscussed. In this paper we address the problem of computingnumerically the so-called envelope solutions to these equations.In particular we suggest a numerical method for the solutionof this problem-one which is in spirit a predictor-correctormethod. We discuss the numerical difficulties encountered andgive some numerical examples.     

A Generalized Smoother for Linear Ordinary Differential Equations

Ordinary differential equations (ODEs) are equalities involving a function and its derivatives that define the evolution of the function over a prespecified domain. The applications of ODEs range from simulation and prediction to control and diagnosis in diverse fields such as engineering, physics, medicine, and finance. Parameter estimation is often required to calibrate these theoretical models to data. While there are many methods for estimating ODE parameters from partially observed data, they are invariably subject to several problems including high computational cost, complex estimation procedures, biased estimates, and large sampling variance. We propose a method that overcomes these issues and produces estimates of the ODE parameters that have less bias, a smaller sampling variance, and a 10-fold improvement in computational efficiency. The package GenPen containing the Matlab code to perform the methods described in this article is available online.     

Integrability of Solutions of Nonlinear Elliptic Equations with Right-Hand Sides from Classes Close to L 1

We establish a number of results on the integrability of the entropy and the weak solutions of the Dirichlet problem for nonlinear elliptic equations of second order depending on the integrability properties of the right-hand sides of these equations.     

常微分方程解的存在区间和周期解

讨论解的存在区间,说明周期函数如何是周期解以及它和Poincaré映射的关系.对周期的Riccati方程研究了周期解的个数,是文[8]中的定理1的一个补充,同时也研究了周期捕获的人口方程解的存在区间和周期解问题.     

Existence of Solutions for Fractional Differential Equations with Conformable Fractional Differential Derivatives

A class of nonlinear fractional differential equations with conformable fractional differential derivatives is studied. Firstly, Green's function and its properties are given. Secondly, some new existence and multiplicity conditions of positive solutions are obtained by the use of Leggett-Williams fixed-point theorems on cone.     

Time Optimal Control for Some Ordinary Differential Equations with Multiple Solutions

This paper studies a time optimal control problem for a class of ordinary differential equations. The control systems may have multiple solutions. Based on the properties fulfilled by the solutions of the concerned equations, we get both the existence and the Pontryagin maximum principle for optimal controls.     

AF—代数的闭的Jordan理想

讨论AF-代数的闭的Jordan理想。我们证明了AF-代灵敏的一个闭的子集是其一Jordan理想的充分必要条件是它是一个结合理想。     

Analytic Solutions for a Class of Nonlinear Ordinary Differential Equations

In this article, existence and uniqueness of analytic solutions to a class of problems of the form $ zG^{prime prime }(z)+J(z)G^{prime }(z)+F(G(z))=0, G(0)=G_0 $ are considered, where J is analytic in some neighborhood about 0 and F is analytic in some neighborhood of G 0 . This is a generalization of a class of problems considered by Rothe (F. Rothe (1997). A variant of Frobenius' method for the Emden-Fowler equation. Applicable Analysis , 66 , 227-245).     

Asymptotic Representations for the Solutions of Nonautonomous Ordinary Differential Equations

Ukrainian Mathematical Journal - The conditions of existence and asymptotic representations as t ↑ �� (�� ≤ + ∞) are obtained for one class of...     

Periodic Solutions for a Class of Second-Order Ordinary Differential Equations

This paper is devoted to the study of periodic solutions for a class of second-order ordinary differential equations by utilizing a technique for obtaining solutions to free problems in the calculus of variations originating in the work of Carathéodory (Ref. 1, 1935). The key of this technique is to find some suitable transformation which transfers the periodic solution problem to an equivalent variational problem in which the minimizer is more easily determined. Some applications are presented to illustrate the utility of this technique.Supported by NSFC Grant 10401013, 985 Project of Jilin University and Graduate Innovation Lab of Jilin University. The authors thank Professor D. A. Carlson and the anonymous referees for valuable suggestions and helpful comments.     

一类拟线性常微分方程的多解

说明一类拟线性特征值问题有两个正解;一个大解,一个小解。同时本也证明小解是一个山路解当参数大时发展成为尖解。