Current-Processing Current-Controlled Universal Biquad Filter

This paper presents a current-processing current-controlled universal biquad filter. The proposed filter employs only two current controlled current conveyor transconductance amplifiers (CCCCTAs) and two grounded capacitors. The proposed configuration can be used either as a single input three outputs (SITO) or as three inputs single output (TISO) filter. The circuit realizes all five different standard filter functions i.e. low-pass (LP), band-pass (BP), high-pass (HP), band-reject (BR) and all-pass (AP). The circuit enjoys electronic control of quality factor through the single bias current without disturbing pole frequency. Effects of non-idealities are also discussed. The circuit exhibits low active and passive sensitivity figures. The validity of proposed filter is verified through computer simulations using PSPICE

A characterization of the central shell-focusing singularity in spherical gravitational collapse

We give a characterization of the central shell-focusing curvature singularity that can form in the spherical gravitational collapse of a bounded matter distribution obeying the dominant energy condition. This characterization is based on the limiting behaviour of the mass function in the neighbourhood of the singularity. Depending on the rate of growth of the mass as a function of the area radius R, the singularity may be either covered or naked. The singularity is naked if this growth rate is slower than R, covered if it is faster than R, and either naked or covered if the growth rate is same as R.Comment: 12 pages, Latex, significantly revised version, including change of title. Revised version to appear in Classical and Quantum Gravit

Flow behavior at different shear rates for dry powders

Using Discrete Element Simulations (DEM), an effort is made to study the so called “Split bottom ring shear cell” where a slow, quasi-static deformation leads to wide shear bands. Density, velocity and deformation gradients as well as structure and stress tensors, can be computed by a single simulation, by applying time and (local) space averaging. Here, we focus on different shear rates by increasing the rate of rotation of the system

Electronic Structure and Bulk Spin Valve Behavior in Ca3_3Ru2_2O7_7

We report density functional calculations of the magnetic properties and Fermiology of Ca$_3$Ru$_2$O$_7$. The ground state consists of ferromagnetic bilayers, stacked antiferromagnetically. The bilayers are almost but not exactly half-metallic. In the ferromagnetic state opposite spin polarizations are found for in-plane and out-of-plane transport. Relatively high out of plane conductivity is found for the majority spin, which is relatively weakly conductive in-plane. In the ground state in-plane quantities are essentially the same, but the out of plane transport is strongly reduced.Comment: 5 page