Fluid Flows Around Floating Bodies, I: The Hydrostatic Case

We consider the hydrostatic configuration of a body floating freely on a liquid. Under the influence of gravitational and capillary forces there exists an equilibrium solution with contact angle π/2. This solution is the minimizer of a variational problem with an obstacle condition; the corresponding free boundary consists of the curve where the capillary surface meets the floating body.     

A note on the interpretation of closed H-surfaces in physical terms

A variational problem for closed H-surfaces contains conditions which firstly are not evident if compared with related geometrical problems. The formulation turns out to be quite natural, however, if the problem is derived from a mechanical one and hence can be interpreted in physical terms.     

Surfaces of prescribed mean curvature in a cone

We show existence of surfaces of prescribed mean curvature in central projection for such values of the mean curvature for which estimates for the corresponding Euler–Lagrange equations are generally not known. This is achieved by extending the variational problem to the space \({BV(\Omega)}\), where graphs in a cone must satisfy a side condition, and using variational methods. Moreover, we give an example of a solution in \({BV(\Omega)}\) which does not solve the Dirichlet problem for the Euler-Lagrange equation.     

Analyticity for the Navier-Stokes equations governed by surface tension on the free boundary

A free boundary problem for an incompressible viscous fluid is considerd; the boundary is to be determined by equilibrium conditions involving the fluid's stress tensor and its surface tension. It is proved that if the data of the problem are analytic then the free boundary, the velocity vector, and the pressure are all analytic.     

On a variational problem for an elastic membrane supporting a heavy ball

An elastic membrane or a soap film is investigated that is bounded by a planar curve and supports a heavy ball. The ball is allowed to move on the surface, and its position, together with the shape of the membrane will furnish a minimum to the potenial energy. This leads to an obstacle problem for Dirichlet's integral or the area functional where only the shape of the obstacle but not its position in space is given.     

Eine Außenraumaufgabe für die instationären Navier-Stokes-Gleichungen

Ohne ZusammenfassungDem Andenken an meinen Vater     

Isolation methods for the volatile components of grapefruit juice. Distillation and solvent extraction methods

Summary Five different methods including solvent extraction, distillation and simultaneous distillation-solvent extraction (SDE) have been compared for the isolation of the volatile components of grapefruit juice. The search for an adequare procedure was directed to obtaining aroma concentrates with an odour resembling that of the original grapefruit juice. The methods have also been compared in terms of some experimental parameters. The concentrates have been analyzed by fused-silica, capillary gas chromatography and the GC patterns have been compared in terms of the recovery efficiencies for high-, medium-, and low-volatility components. The SDE methods gave the best results, particularly when using the apparatus proposed by Godefrootet al.     

Mössbauer spectroscopy investigation of the persistent photoionization of the DX-center in129mTe-implanted GaAs

Persistent photoionization of the DX-center in GaAs implanted with^129mTe isotopes is observed with Mössbauer spectroscopy. The time constant of the relaxation from the donor site to the DX-center defect site, after the illumination is stopped, is measured as a function of temperature. A small energy barrier for capture (1 meV) is derived from these measurements.