Accretion onto black holes in wind-fed binaries and in collapsars forms small rotating discs with peculiar properties. Such “mini-discs” accrete on the free-fall time without help of viscosity and nevertheless can have a high radiative efficiency. The inviscid mini-disc model was previously constructed for a non-rotating black hole. We extend the model to the case of a spinning black hole, calc...

We study the dynamics and thermodynamics of a probe D3-brane in the rotating D3-brane background and in its extremal limit, which is a multicenter configuration of D3-branes distributed uniformly on a disc. In the extremal background, if the angular momentum of the probe does not vanish, the probe is always bounced back at some turning point. When its angular momentum vanishes, in the disc plan...

The analysis of steady state creep in a rotating disc made of Al-SiCp composite having variable thickness has been carried using Sherby’s constitutive model. The creep parameters have been evaluated using the available experimental results in the literature using regression analysis. Three variations in the thickness (constant, linearly and hyperbolic varying thickness) of the disc have been co...

We present elastomeric membrane valves integrated into a centrifugal microfluidic platform for precise control of fluid on a disc. The amount of the fluid passing through the valves, which depends on the rotating speed of the disc and the membrane thickness, has been characterized, and could be precisely controlled by tuning the disc motion.

Rotating Shadowband Pyranometers (RSPs) have been deployed to measure global, beam, and diffuse irradiance because they do not require manual adjustment of trackers. However, a RSP requires the use of solar cell based pyranometers which underestimate diffuse irradiance by 20-30% under clear sky conditions. Algorithms were derived to address many of the systematic errors in solar cell based meas...

The question of whether the same acceleration field that is found in a rigid uniformly rotating disc can annul a gravitational field is answered in the negative because their curvatures are different. There is an exact correspondence between a uniformly rotating disc and hyperbolic geometry of constant curvature, while, gravitational fields require non-constant, negative curvature. The connecti...

We calculate the accretion disc temperature profiles, disc luminosities and boundary layer luminosities for rapidly rotating neutron stars considering the full effect of general relativity. We compare the theoretical values of these quantities with their values inferred from EXOSAT data for four low mass X–ray binary sources: XB 182030, GX 17+2, GX 9+1 and GX 349+2 and constrain the values of s...