78,408 research outputs found
Exploding wire initiation and electrical operation of a 40-kV system for arc-heated drivers up to 10 feet long
Exploding wire initiation and electrical operation of 40 kV system for arc heated drivers up to 10 feet lon
A model for structural defects in nanomagnets
A model for describing structural pointlike defects in nanoscaled
ferromagnetic materials is presented. Its details are explicitly developed
whenever interacting with a vortex-like state comprised in a thin nanodisk.
Among others, our model yields results for the vortex equilibrium position
under the influence of several defects along with an external magnetic field in
good qualitative agreement with experiments. We also discuss how such defects
may affect the vortex motion, like its gyrotropic oscillation and dynamical
polarization reversal.Comment: 8 pages, resubmitted to Journal of Applied Physic
Arc driver operation for either efficient energy transfer or high-current generator
An investigation is made to establish predictable electric arcs along triggered paths for research purposes, the intended application being the heating of the driver gas of a 1 MJ electrically driven shock tube. Trigger conductors consisting of wires, open tubes, and tubes pressurized with different gases were investigated either on the axis of the arc chamber or spiraled along the chamber walls. Design criteria are presented for successful arc initiation with reproducible voltage-current characteristics. Results are compared with other facilities and several application areas are discussed
The impact of kinetic effects on the properties of relativistic electron-positron shocks
We assess the impact of non-thermally shock-accelerated particles on the
magnetohydrodynamic (MHD) jump conditions of relativistic shocks. The adiabatic
constant is calculated directly from first principle particle-in-cell
simulation data, enabling a semi-kinetic approach to improve the standard fluid
model and allowing for an identification of the key parameters that define the
shock structure. We find that the evolving upstream parameters have a stronger
impact than the corrections due to non-thermal particles. We find that the
decrease of the upstream bulk speed yields deviations from the standard MHD
model up to 10%. Furthermore, we obtain a quantitative definition of the shock
transition region from our analysis. For Weibel-mediated shocks the inclusion
of a magnetic field in the MHD conservation equations is addressed for the
first time
Influence of Refractory Periods in the Hopfield model
We study both analytically and numerically the effects of including
refractory periods in the Hopfield model for associative memory. These periods
are introduced in the dynamics of the network as thresholds that depend on the
state of the neuron at the previous time. Both the retrieval properties and the
dynamical behaviour are analyzed.Comment: Revtex, 7 pages, 7 figure
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