Hamiltonian description of singular solutions of the Liouville equation

Theoretical and Mathematical Physics -     

A class of existence results for the singular Liouville equation

We consider a class of elliptic PDEs on closed surfaces with exponential nonlinearities and Dirac deltas on the right-hand side. The study arises from abelian Chern–Simons theory in self-dual regime, or from the problem of prescribing the Gaussian curvature in presence of conical singularities. A general existence result is proved using global variational methods: the analytic problem is reduced to a topological problem concerning the contractibility of a model space, the so-called space of formal barycenters, characterizing the very low sublevels of a suitable functional.     

Perturbation of the two-soliton solution to the KdV equation

The Cauchy problem for the perturbed Korteveg-de Vries equation with the two-soliton initial data is considered. Differential equations for the slow deformation of the parameters—amplitudes and phase shifts—are derived. It is shown that the phase shift of the slow soliton depends on the deformation of the fast solition. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 112, No. 1, pp. 92–102.     

Blow-up phenomena for the Liouville equation with a singular source of integer multiplicity

We are concerned with the existence of blowing-up solutions to the following boundary value problem

$?\mathrm{\Delta }u=\lambda a(x)e^u?4\pi N{\delta }_0\text{ in }\mathrm{\Omega },u=0\text{ on }?\mathrm{\Omega },$

where Ω is a smooth and bounded domain in ${\mathbb{R}}^2$ such that $0\in \mathrm{\Omega }$, $a(x)$ is a positive smooth function, N is a positive integer and $\lambda >0$ is a small parameter. Here ${\delta }_0$ defines the Dirac measure with pole at 0. We find conditions on the function a and on the domain Ω under which there exists a solution $u_{\lambda }$ blowing up at 0 and satisfying $\lambda {\int }_{\mathrm{\Omega }}a(x)e^{u_{\lambda }}\to 8\pi (N+1)$ as $\lambda \to 0^{+}$.     

Sectorial solution to semilinear singular partial differential equation

We shall show the solvability of semilinear Fuchsian partial differential systems in a multi-sectorial domain. Our equation contains a linearizing equation of a singular vector field to its linear part when so-called small denominators occur. We will show the existence of an analytic solution in a multi-sectorial domain without assuming any Diophantine condition.     

On the existence of a solution to a singular integral equation in electromagnetic reflection

For a singular integral equation arising in a modified approach to boundary integral equations for exterior boundary-value problems from the theory of electromagnetic reflection an existence proof is given.     

Existence of solution for a singular critical elliptic equation

In this paper, a singular semilinear elliptic problem involving the critical Sobolev exponent is studied by variational method, the existence of a solution is proved under certain conditions. The Hardy inequality is used and plays an important role in the discussion.     

On solution sequences of the singular Liouville equations with an integral constraint

In this paper,we analyze the blow-up behavior of sequences{uk}satisfying the following conditionsΔuk=|x|2αk V k eukinΩ,(0.1)whereΩR2,V k→V in C1,|Vk|≤A,0a≤Vk≤b,0≤αk→α∈(0,∞),andΩ|x|2αkeuk dx≤Λ1.(0.2)Furthermore,we assume that there exists someq∈(1,2)such that rq 2Br(p)|uk|qdx≤Λ2(0.3)for anyB r(p)Ω.As a result,we give a new proof of the concentration-compactness theorem for the mean feld equation.     

Local estimate on singular solution to scalar curvature equation

In this paper, we study the local behavior of a positive singular solution u near its singular points of the following equation:

     

Approximate solution of one singular integro-differential equation

In this paper we construct and theoretically justify a computational scheme for solving the Cauchy problem for a singular integro-differential equation of the first-order, where the integral over a segment of the real axis is understood in the sense of the Cauchy principal value. In addition, we study and solve approximately the integral equation with a special logarithmic kernel. We obtain uniform estimates for errors of approximate formulas. Orders of errors of approximate solutions are proved to be proportional to the order of the approximation error for the derivative of the density of the singular integral in the integro-differential equation.     

Liouville theorems for the solution of a second-order linear parabolic equation with discontinuous coefficients

Theorems of Liouville type are proved for a very general second-order parabolic equation. Smoothness conditions are not imposed on the coefficients; however, it is required that a Cordes condition be satisfied which denotes the nearness to the identity of the coefficient matrix for the second derivatives.Translated from Matematicheskiee Zametki, Vol. 5, No. 5, pp. 599–606, May, 1969.     

Liouville type equation with exponential Neumann boundary condition and with singular data

In this paper we will analyze the blow-up behaviors of solutions to the singular Liouville type equation with exponential Neumann boundary condition. We generalize the Brezis–Merle type concentration-compactness theorem to this Neumann problem. Then along the line of the Li–Shafrir type quantization property we show that the blow-up value \(m(0) \in 2\pi \mathbb N\cup \{ 2\pi (1+\alpha )+2\pi (\mathbb N\cup \{0\})\}\) if the singular point 0 is a blow-up point. In the end, when the boundary value of solutions has an additional condition, we can obtain the precise blow-up value \(m(0)=2\pi (1+\alpha )\).     

Galerkin solution of a singular integral equation with constant coefficients

Galerkin methods are used to approximate the singular integral equation

with solution φ having weak singularity at the endpoint −1, where a, b≠0 are constants. In this case φ is decomposed as φ(x)=(1−x)^α(1+x)^βu(x), where β=−α, 0<α<1. Jacobi polynomials are used in the discussions. Under the conditions fH^μ[−1,1] and k(t,x)H^μ,μ[−1,1]×[−1,1], 0<μ<1, the error estimate under a weighted L² norm is O(n^−μ). Under the strengthened conditions f^″H^μ[−1,1] and , 2α−<μ<1, the error estimate under maximum norm is proved to be O(n^2α−−μ+), where , >0 is a small enough constant.     

Numerical solution of a singular integral equation appearing in magnetohydrodynamics

The numerical solution for the velocity and induced magnetic field has been obtained for the MHD flow through a rectangular pipe with perfectly conducting electrodes. The problem reduces to the solution of a singular integral equation which has been solved numerically. It is found that as the Hartmann number is increased the velocity profile shows a flattening tendency and the flux through a section is reduced. Also as compared with the case of nonconducting walls the flux is found to be smaller. Graphs and tables are given for the solution of the integral equation and the velocity and induced magnetic field.

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Zusammenfassung Für den MHD Fluß durch ein rechteckiges Rohr mit gut leitenden Elektroden wurde die numerische Lösung für die Geschwindigkeit und das induzierte Feld ermittelt. Das Problem ließ sich auf eine singuläre Integralgleichung zurückführen, die numerisch gelöst wurde. Es hat sich herausgestellt, daß wenn die Hartmann-Zahl größer wird, das Geschwindigkeitsprofil eine Tendenz zur Abflachung zeigt und der Fluß durch den Querschnitt zurückgeht. Im Vergleich mit dem Einsatz von nicht leitenden Wänden wurde ebenfalls ein geringerer Fluß festgestellt. Für die Lösung der Integralgleichung, die Geschwindigkeit und das magnetische induzierte Feld sind graphische Darstellungen und Tabellen angegeben.

     

Uniqueness of singular solution of semilinear elliptic equation

In this paper, we study asymptotic behavior of solution near 0 for a class of elliptic problem. The uniqueness of singular solution is established.