On the definition of solution to the total variation flow

We show that the notions of weak solution to the total variation flow based on the Anzellotti pairing and the variational inequality coincide under some restrictions on the boundary data. The key ingredient in the argument is a duality result for the total variation functional, which is based on an approximation of the total variation by area-type functionals.

Partial Regularity for Harmonic Maps into Spheres at a Singular or Degenerate Free Boundary

We prove partial regularity of weakly stationary harmonic maps with (partially) free boundary data on manifolds where the domain metric may degenerate or become singular along the free boundary at the rate $$d^\alpha $$ d α for the distance function d from the boundary.

The K–T boundary strata north of Korsnæb, Stevns Klint, Denmark – evolution and geometry revealed in a long, horizontal profile

A 460 m long profile of the Cretaceous–Paleogene (K–T) boundary strata at Stevns Klint was measured by the late Professor A. Rosenkrantz probably in 1944. The measured profile was inherited by Finn Surlyk around 1974 together with other original boundary data. This material was dug up in a long-forgotten drawer in connection with detailed field work by the co-authors on the boundary succession in the late spring and summer of 2021. The profile illustrates the stratigraphy, geometry and palaeotopography of the boundary strata in unprecedented detail. The part of the cliff illustrated in the profile is today partly covered by beach ridges composed of flint rubble but is situated below the finest section of the lower Danian bryozoan mounds exposed at Stevns Klint. This coastal section is situated immediately adjacent to a large limestone quarry and was planned to be quarried away around 1937, but was saved by A. Rosenkrantz who demonstrated its great scientific and educational value to the authorities.

Normalized solutions to a Schrödinger–Bopp–Podolsky system under Neumann boundary conditions

In this paper, we study a Schrödinger–Bopp–Podolsky (SBP) system of partial differential equations in a bounded and smooth domain of [Formula: see text] with a nonconstant coupling factor. Under a compatibility condition on the boundary data we deduce existence of solutions by means of the Ljusternik–Schnirelmann theory.

A strong maximum principle for the fractional laplace equation with mixed boundary condition

In this work we prove a strong maximum principle for fractional elliptic problems with mixed Dirichlet–Neumann boundary data which extends the one proved by J. Dávila (cf. [11]) to the fractional setting. In particular, we present a comparison result for two solutions of the fractional Laplace equation involving the spectral fractional Laplacian endowed with homogeneous mixed boundary condition. This result represents a non–local counterpart to a Hopf’s Lemma for fractional elliptic problems with mixed boundary data.

A Cantilever Beam Problem with Small Deflections and Perturbed Boundary Data

The boundary value problem of a fourth-order beam equation u 4 = λ f x , u , u ′ , u ″ , u ′ ′ ′ , 0 ≤ x ≤ 1 is investigated. We formulate a nonclassical cantilever beam problem with perturbed ends. By determining appropriate values of λ and estimates for perturbation measurements on the boundary data, we establish an existence theorem for the problem under integral boundary conditions u 0 = u ′ 0 = ∫ 0 1 p x u x d x , u ″ 1 = u ′ ′ ′ 1 = ∫ 0 1 q x u ″ x d x , where p , q ∈ L 1 0 , 1 , and f is continuous on 0 , 1 × 0 , ∞ × 0 , ∞ × − ∞ , 0 × − ∞ , 0 .

Inverse Problems with Unknown Boundary Conditions and Final Overdetermination for Time Fractional Diffusion-Wave Equations in Cylindrical Domains

Inverse problems to reconstruct a solution of a time fractional diffusion-wave equation in a cylindrical domain are studied. The equation is complemented by initial and final conditions and partly given boundary conditions. Two cases are considered: (1) full boundary data on a lateral hypersurface of the cylinder are given, but the boundary data on bases of the cylinder are specified in a neighborhood of a final time; (2) boundary data on the whole boundary of the cylinder are specified in a neighborhood of the final time, but the cylinder is either a cube or a circular cylinder. Uniqueness of solutions of the inverse problems is proved. Uniqueness for similar problems in an interval and a disk is established, too.