17,638 research outputs found
Inviscid analysis of jet injection between two moving streams
An analytical method is developed for determining the flow interaction when a two-dimensional jet is injected between two moving streams. The jet is flowing out of channel and is turned as it enters between the external streams. The local velocity variation resulting from the flow interaction provides a static pressure variation along the jet bounding streamlines that is a priori unknown. Hense, the flow must be obtained by coupling the three flow regions (the jet and the free stream on either side) along the jet boundaries. Both external streams have the same total pressure, which is different from that in the jet. The solution is for the condition that the total pressure in the jet does not differ from the free-stream value by a large amount compared with the free-stream dynamic head. Results are given for the shape of the jet boundaries for various injection configurations
Potential of a New Technique for Remote Sensing of Hydrocarbon Accumulations and Blind Uranium Deposits: Buried Lif Thermoluminescence Dosimeters
Buried thermoluminescence dosimeters may be useful in remote sensing of petroleum and natural gas accumulations and blind uranium deposits. They act as integrating detectors that smooth out the effects of environmental variations that affect other measuring systems and result in irregularities and poor repeatability in measurements made during gas and radiometric surveys
High efficiency deterministic Josephson Vortex Ratchet
We investigate experimentally a Josephson vortex ratchet -- a fluxon in an
asymmetric periodic potential driven by a deterministic force with zero time
average. The highly asymmetric periodic potential is created in an underdamped
annular long Josephson junction by means of a current injector providing
efficiency of the device up to 91%. We measured the ratchet effect for driving
forces with different spectral content. For monochromatic high-frequency drive
the rectified voltage becomes quantized. At high driving frequencies we also
observe chaos, sub-harmonic dynamics and voltage reversal due to the inertial
mass of a fluxon.Comment: accepted by PRL. To see status click on
http://134.2.74.170:88/cnt/cond-mat_0506754.htm
Subcritical Superstrings
We introduce the Liouville mode into the Green-Schwarz superstring. Like
massive supersymmetry without central charges, there is no kappa symmetry.
However, the second-class constraints (and corresponding Wess-Zumino term)
remain, and can be solved by (twisted) chiral superspace in dimensions D=4 and
6. The matter conformal anomaly is c = 4-D < 1. It thus can be canceled for
physical dimensions by the usual Liouville methods, unlike the bosonic string
(for which the consistency condition is c = D <= 1).Comment: 9 pg., compressed postscript file (.ps.Z), other formats (.dvi, .ps,
.ps.Z, 8-bit .tex) available at
http://insti.physics.sunysb.edu/~siegel/preprints/ or at
ftp://max.physics.sunysb.edu/preprints/siege
A new measurement of the lifetime of the positive pion
Digital timing method for measuring positive pion lifetim
Energy and width measurements of low-Z pionic X-ray transitions
High resolution spectrometric measurement of energy and natural line widths of 2p-1s pionic X ray transitions, as well as muonic transition energies in Li, Be, B, and C isotope
Giant radiation heat transfer through the micron gaps
Near-field heat transfer between two closely spaced radiating media can
exceed in orders radiation through the interface of a single black body. This
effect is caused by exponentially decaying (evanescent) waves which form the
photon tunnel between two transparent boundaries. However, in the mid-infrared
range it holds when the gap between two media is as small as few tens of
nanometers. We propose a new paradigm of the radiation heat transfer which
makes possible the strong photon tunneling for micron thick gaps. For it the
air gap between two media should be modified, so that evanescent waves are
transformed inside it into propagating ones. This modification is achievable
using a metamaterial so that the direct thermal conductance through the
metamaterial is practically absent and the photovoltaic conversion of the
transferred heat is not altered by the metamaterial.Comment: 4 pages, 3 figure
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