332 research outputs found
Corral systems for handling and sorting hogs (1993)
Construction of semi-confinement feeding floors for swine has increased in recent years. Available plans concentrate on design of the confinement area and feed handling. As producers expand, they need more efficient ways to sort, handle and load hogs. Additional planning is required to design smooth flow patterns for livestock handling into the basic production unit
Detection of mechanical resonance of a single-electron transistor by direct current
We have suspended an Al based single-electron transistor whose island can
resonate freely between the source and drain leads forming the clamps. In
addition to the regular side gate, a bottom gate with a larger capacitance to
the SET island is placed underneath to increase the SET coupling to mechanical
motion. The device can be considered as a doubly clamped Al beam that can
transduce mechanical vibrations into variations of the SET current. Our
simulations based on the orthodox model, with the SET parameters estimated from
the experiment, reproduce the observed transport characteristics in detail.Comment: 4 pages, 3 figure
Damping in high-frequency metallic nanomechanical resonators
We have studied damping in polycrystalline Al nanomechanical resonators by
measuring the temperature dependence of their resonance frequency and quality
factor over a temperature range of 0.1 - 4 K. Two regimes are clearly
distinguished with a crossover temperature of 1 K. Below 1 K we observe a
logarithmic temperature dependence of the frequency and linear dependence of
damping that cannot be explained by the existing standard models. We attribute
these phenomena to the effect of the two-level systems characterized by the
unexpectedly long (at least two orders of magnitude longer) relaxation times
and discuss possible microscopic models for such systems. We conclude that the
dynamics of the two-level systems is dominated by their interaction with
one-dimensional phonon modes of the resonators.Comment: 5 pages, 3 figure
Coherent superconducting quantum pump
We demonstrate non-adiabatic charge pumping utilizing a sequence of coherent
oscillations between a superconducting island and two reservoirs. Our method,
based on pulsed quantum state manipulations, allows to speedup charge pumping
to a rate which is limited by the coupling between the island and the
reservoirs given by the Josephson energy. Our experimental and theoretical
studies also demonstrate that relaxation can be employed to reset the pump and
avoid accumulation of errors due to non-ideal control pulses.Comment: 4 pages, 3 figure
O gênero Catasetum Rich. ex Kunth (Orchidaceae, Catasetinae) no Estado do Paraná, Brasil
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