32,557 research outputs found
Dynamics of Charged Bulk Viscous Collapsing Cylindrical Source With Heat Flux
In this paper, we have explored the effects of dissipation on the dynamics of
charged bulk viscous collapsing cylindrical source which allows the out follow
of heat flux in the form of radiations. Misner-Sharp formulism has been
implemented to drive the dynamical equation in term of proper time and radial
derivatives. We have investigated the effects of charge and bulk viscosity on
the dynamics of collapsing cylinder. To determine the effects of radial heat
flux, we have formulated the heat transport equations in the context of
Mller-Israel-Stewart theory by assuming that thermodynamics
viscous/heat coupling coefficients can be neglected within some approximations.
In our discussion, we have introduced the viscosity by the standard
(non-casual) thermodynamics approach. The dynamical equations have been coupled
with the heat transport equation equation, the consequences of resulting
coupled heat equation have been analyzed in detail.Comment: 17 Pages, no figur
Hardware synthesis from DDL description
The details of digital systems can be conveniently input into the design automation system by means of hardware description language (HDL). The computer aided design and test (CADAT) system at NASA MSFC is used for the LSI design. The digital design language (DDL) was selected as HDL for the CADAT System. DDL translator output can be used for the hardware implementation of the digital design. Problems of selecting the standard cells from the CADAT standard cell library to realize the logic implied by the DDL description of the system are addressed
High Bandwidth Atomic Magnetometery with Continuous Quantum Non-demolition Measurements
We describe an experimental study of spin-projection noise in a high
sensitivity alkali-metal magnetometer. We demonstrate a four-fold improvement
in the measurement bandwidth of the magnetometer using continuous quantum
non-demolition (QND) measurements. Operating in the scalar mode with a
measurement volume of 2 cm^3 we achieve magnetic field sensitivity of 22
fT/Hz^(1/2) and a bandwidth of 1.9 kHz with a spin polarization of only 1%. Our
experimental arrangement is naturally back-action evading and can be used to
realize sub-fT sensitivity with a highly polarized spin-squeezed atomic vapor.Comment: 4 page
Stroboscopic back-action evasion in a dense alkali-metal vapor
We explore experimentally quantum non-demolition (QND) measurements of atomic
spin in a hot potassium vapor in the presence of spin-exchange relaxation. We
demonstrate a new technique for back-action evasion by stroboscopic modulation
of the probe light. With this technique we study spin noise as a function of
polarization for atoms with spin greater than 1/2 and obtain good agreement
with a simple theoretical model. We point that in a system with fast
spin-exchange, where the spin relaxation rate is changing with time, it is
possible to improve the long-term sensitivity of atomic magnetometry by using
QND measurements
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