A hypothesis is presented that the irregular shapes of asteroids and cometary nuclei can be modeled by using lognormal statistics (Gaussian random sphere). The Gaussian sphere is fully described by the mean and covariance function of the radius. A suitable covariance function is devised here for the generation of sample Gaussian spheres that closely resemble the shapes observed for asteroids. T...

Though it is generally assumed that massive molecular clouds are the progenitors of globular clusters, their detailed formation mechanism is still unclear. Standard scenarios based on the collapse of a smooth matter distribution suffer from strong requirements with respect to cluster formation time scale, binding energy and star formation efficiency. An alternative model assuming cluster format...

We report the observation of the spontaneous separation of vertically vibrated mixtures of fine bronze and glass spheres of similar diameters. At low frequencies and at sufficient vibrational amplitudes, a sharp boundary forms between a lower region of glass and an upper region of the heavier bronze. The boundary undergoes various oscillations, including periodic tilting motion, but remains ext...

We report experimental studies of the effect of interstitial gas on mass-density segregation in a vertically vibrated mixture of equal-sized bronze and glass spheres. Sufficiently strong vibration in the presence of interstitial gas induces vertical segregation into sharply separated bronze and glass layers. We find that the segregated steady state (i.e., bronze or glass layer on top) is a sens...

Magnetic sensor macrospheres (MagSeMacs), i.e., stainless steel spheres coated with optical chemical sensors, are presented as an alternative to existing optical sensor patches and fiber-optical dip-probes. Such spheres can either be reversibly attached to the tip of an optical fiber (dip-probe) or trapped inside a vessel for read-out through the side wall. Moving the magnetic separator at the ...

The dynamics and velocity distributions for a 2D granular gas of nonspherical particles are studied experimentally. The experiment consists of a horizontal plate that is vertically shaken to drive the dynamics of up to a few thousand macroscopic dimers, spherical pairs that are loosely connected by a rod that allows the particles some freedom to change their aspect ratio. The behavior of a gran...

Ferrofluid spin-up flow has been studied in finite height cylinders and spheres subjected to a uniform rotating magnetic field. Ultrasound measurements in finite height cylinders with a free surface show the presence of surface driven flows as well as bulk flows. In finite height cylinders with a cover, only bulk flows exist. Ultrasound measurements in fully filled spheres of ferrofluid give ne...