1,834 research outputs found
Analysis of dynamic characteristics of fluid force induced by labyrinth seal
Flow patterns of the labyrinth seal are experimentally investigated for making a mathematical model of labyrinth seal and to obtain the flow induced force of the seal. First, the flow patterns in the labyrinth chamber are studied on the circumferential flow using bubble and on the cross section of the seal chamber using aluminum powder as tracers. And next, the fluid force and its phase angle are obtained from the measured pressure distribution in the chamber and the fluid force coefficients are derived from the fluid force and the phase angle. Those are similar to the expression of oil film coefficients. As a result, it is found that the vortices exist in the labyrinth chambers and its center moves up and down periodically. The pressure drop is biggest in the first stage of chambers and next in the last stage of chambers
Possibility of Macroscopic resonant Tunneling near the Superconductor- Insulator Transition in YBaCuO Thin Films
Experimental results of I-V characteristics near the superconductor-insulator
transition observed for disorder-tuned YBaCuO thinfilms are presented. The I-V
characteristics exibit new quasiperiodic structures as a function of the
current. The current interval, the number of the dI/dV peaks, and the magnetic
field dependence of the peaks are consistent with the theoretical predictions
of the resonant tunneling of a phase particle ina tilted-cosine potential for
asingle Josephson junction with small capacitance.Comment: 7 pages, 4 figures, in press (Europhys. Lett.
Scalable Spin Amplification with a Gain over a Hundred
We propose a scalable and practical implementation of spin amplification
which does not require individual addressing nor a specially tailored spin
network. We have demonstrated a gain of 140 in a solid-state nuclear spin
system of which the spin polarization has been increased to 0.12 using dynamic
nuclear polarization with photoexcited triplet electron spins. Spin
amplification scalable to a higher gain opens the door to the single spin
measurement for a readout of quantum computers as well as practical
applications of nuclear magnetic resonance (NMR) spectroscopy to infinitesimal
samples which have been concealed by thermal noise.Comment: 6 pages, 7 figure
Pressure effects on the superconducting properties of YBa_2Cu_4O_8
Measurements of the magnetization under high hydrostatic pressure (up to 10.2
kbar) in YBa_2Cu_4O_8 were carried out. From the scaling analysis of the
magnetization data the pressure induced shifts of the transition temperature
T_c, the volume V and the anisotropy \gamma have been obtained. It was shown
that the pressure induced relative shift of T_c mirrors essentially that of the
anisotropy. This observation uncovers a novel generic property of anisotropic
type II superconductors, that inexistent in the isotropic case.Comment: 4 pages, 3 figure
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