An approximate analytic solution of the Blasius problem

The [4/3] Pade approximant for the derivative is modified so that the resulting expression has the required asymptotic behavior. This gives an analytical result which represents the solution of the classical Blasius problem on the whole domain.     

A solution of the Blasius problem

The classical Blasius boundary layer problem in its simplest statement consists in finding an initial value for the function satisfying the Blasius ODE on semi-infinite interval such that a certain condition at infinity be satisfied. Despite an apparent simplicity of the problem and more than a century of effort of numerous scientists, this elusive constant is determined at present numerically and not much better than it was done by Töpfer in 1912. Here we find this (Blasius) constant rigorously in closed form as a convergent series of rational numbers. Asymptotic behaviour, and lower and upper bounds for the partial sums of the series are also given.     

On the solutions of analytic equations

Inventiones mathematicae -     

Existence of analytic solutions for the classical Stefan problem

We prove that under mild regularity assumptions on the initial data the two-phase classical Stefan problem admits a (unique) solution that is analytic in space and time.     

Two-dimensional filtration problem for solutions in a nonhomogeneous porous medium

We present a mathematical model of underground leaching by solutions filtering through a porous medium. The model describes the motion of solutions from injection to extraction boreholes, as well as dissolution and secondary deposition in reduced-pH regions. A numerical algorithm has been developed for solving the problem on a plane in the general case of a homogeneous medium that contains regions with various nonhomogeneities. The algorithm combines triangulation of the region with the finite element method. The model also allows slow variation over time of some of the process parameters, such as porosity and the filtration coefficient. Numerical results are reported for various cases. The model qualitatively describes the main regularities of underground leaching and can be used to study and understand the detailed dynamics of these processes. The model also fills gaps in geological prospecting data, and extraction curves constructed for different wells can be applied to determine the approximate location of a particular nonhomogeneity. Mathematical modeling can help to optimize mineral extraction by underground leaching. Translated from Prikladnaya Matematika i Informatika, No. 29, pp. 29–55, 2008.     

Nonradial solutions of a nonhomogeneous semilinear elliptic problem with linear growth

In this paper we consider the problem

     

Existence of three solutions to a second-order nonhomogeneous multipoint boundary-value problem

This paper is concerned with a nonhomogeneous multipoint boundary-value problem (BVP) of a second-order differential equation with one-dimensional p-Laplacian. Using multiple fixed-point theorems, new sufficient conditions to guarantee the existence of at least three solutions of this BVP are established. An example is presented to illustrate the main results. The first emphasis of this paper is to show that the approach to get three positive solutions of a BVP by using multiple fixed-point theorems can be extended to treat nonhomogeneous BVPs. The second emphasis is put on the nonlinear term f involved with the first-order delta operator.     

On the solutions of certain linear nonhomogeneous second-order differential equations

The system Nω=(N-α)ω+y, N= bN+aωω^T, N(t)?R^m×m, ω(t)?R^m which originally arose from a model for the pathological behavior of neural networks, is studied. Similar equations can arise in a variety of applications. It is shown that if N(0) is positive definite, then solutions exist for all time. Equilibrium points are determined. N is found to be singular at the equilibrium points, making the analysis of the asymptotic properties of the system non-trivial. The asymptotic behavior when y = 0 is completely described. Some results are proven on the asymptotic behavior of N and ω when y≠0     

On solutions of real analytic equations

Analyticity of solutions , of systems of real analytic equations , is studied. Sufficient conditions for and power series solutions to be real analytic are given in terms of iterative Jacobian ideals of the analytic ideal generated by . In a special case when the 's are independent of , we prove that if a solution satisfies the condition , then is necessarily real analytic.

     

On a nonhomogeneous,nonlinear Dirichlet eigenvalue problem

We consider a nonlinear eigenvalue problem for the Dirichlet $(p,q)$-Laplacian with a sign-changing Carath$\acute{\mathrm{e}}$odory reaction. Using variational tools, truncation and comparison techniques, and critical groups, we prove an existence and multiplicity result which is global in the parameter $\lambda >0$ (bifurcation-type theorem). Our work here complements the recent one by Papageorgiou–Qin–Rădulescu, Bull. Sci. Math. 172 (2021).     

Positive solutions for an n-point nonhomogeneous boundary value problem

This paper is concerned with the solvability of an n-point nonhomogeneous boundary value problem. By using the Krasnoselskii's fixed-point theorem in Banach spaces, some sufficient conditions guaranteeing the existence of at least one positive solution are established for the n-point nonhomogeneous boundary value problem.     

Existence of positive solutions to n-point nonhomogeneous boundary value problem

In this paper, we are concerned with the existence of positive solutions to a n-point nonhomogeneous boundary value problem. By using the Krasnoselskii's fixed point theorem in Banach spaces, some sufficient conditions guaranteeing the existence of positive solution is established for the n-point nonhomogeneous boundary value problem.     

On an analytic generalization of the Busemann-Petty problem

In this paper, we establish an extension of the connections between an analytic generalization of the Busemann-Petty problem and the positive definite distributions. Our results show that the structure of the positive definite distributions in Rn is closely related to the analytic generalization of the Busemann-Petty problem which was posed by Koldobsky.     

On analytic solutions of operator differential equations

We find conditions on a closed operator A in a Banach space that are necessary and sufficient for the existence of solutions of a differential equation y′(t) = Ay(t), t ∈[0,∞),in the classes of entire vector functions with given order of growth and type. We present criteria for the denseness of classes of this sort in the set of all solutions. These criteria enable one to prove the existence of a solution of the Cauchy problem for the equation under consideration in the class of analytic vector functions and to justify the convergence of the approximate method of power series. In the special case where A is a differential operator, the problem of applicability of this method was first formulated by Weierstrass. Conditions under which this method is applicable were found by Kovalevskaya.