130,176 research outputs found
Automatic transponder
A method and apparatus for the automatic, remote measurement of the internal delay time of a transponder at the time of operation is provided. A small portion of the transmitted signal of the transponder is converted to the receive signal frequency of the transponder and supplied to the input of the transponder. The elapsed time between the receive signal locally generated and the receive signal causing the transmission of the transmitted signal is measured, said time being representative of or equal to the internal delay time of the transponder at the time of operation
Ion microprobe mass analysis of lunar samples. Lunar sample program
Mass analyses of selected minerals, glasses and soil particles of lunar, meteoritic and terrestrial rocks have been made with the ion microprobe mass analyzer. Major, minor and trace element concentrations have been determined in situ in major and accessory mineral phases in polished rock thin sections. The Pb isotope ratios have been measured in U and Th bearing accessory minerals to yield radiometric age dates and heavy volatile elements have been sought on the surfaces of free particles from Apollo soil samples
Unifying metastasis--Integrating intravasation, circulation and end organ colonization
Recent technological advances that have enabled the measurement of circulating tumour cells (CTCs) in patients have spurred interest in the circulatory phase of metastasis. Techniques that do not solely rely on a blood sample allow substantial biological interrogation beyond simply counting CTCs
Development of lightweight, fire-retardant, low-smoke, high-strength, thermally stable aircraft floor paneling
Extensive fire resistance and mechanical property tests were conducted on sandwich configurations composed of resin-fiberglass laminates bonded with adhesive to Nomex honeycomb and foam core. The test results were used to select a combination of materials that would improve the fire safety of the airplane without sacrificing mechanical performance of the aircraft floor panels. A test panel is being service evaluated in a commercial aircraft
Exact solution of the one-dimensional deterministic Fixed-Energy Sandpile
In reason of the strongly non-ergodic dynamical behavior, universality
properties of deterministic Fixed-Energy Sandpiles are still an open and
debated issue. We investigate the one-dimensional model, whose microscopical
dynamics can be solved exactly, and provide a deeper understanding of the
origin of the non-ergodicity. By means of exact arguments, we prove the
occurrence of orbits of well-defined periods and their dependence on the
conserved energy density. Further statistical estimates of the size of the
attraction's basins of the different periodic orbits lead to a complete
characterization of the activity vs. energy density phase diagram in the limit
of large system's size.Comment: 4 pages, accepted for publication in Phys. Rev. Let
Properties of the Scalar Universal Equations
The variational properties of the scalar so--called ``Universal'' equations
are reviewed and generalised. In particular, we note that contrary to earlier
claims, each member of the Euler hierarchy may have an explicit field
dependence. The Euler hierarchy itself is given a new interpretation in terms
of the formal complex of variational calculus, and is shown to be related to
the algebra of distinguished symmetries of the first source form.Comment: 15 pages, LaTeX articl
Emissions control for ground power gas turbines
The similarities and differences of emissions reduction technology for aircraft and ground power gas turbines is described. The capability of this technology to reduce ground power emissions to meet existing and proposed emissions standards is presented and discussed. Those areas where the developing aircraft gas turbine technology may have direct application to ground power and those areas where the needed technology may be unique to the ground power mission are pointed out. Emissions reduction technology varying from simple combustor modifications to the use of advanced combustor concepts, such as catalysis, is described and discussed
Gravitational Geons Revisited
A careful analysis of the gravitational geon solution found by Brill and
Hartle is made. The gravitational wave expansion they used is shown to be
consistent and to result in a gauge invariant wave equation. It also results in
a gauge invariant effective stress-energy tensor for the gravitational waves
provided that a generalized definition of a gauge transformation is used. To
leading order this gauge transformation is the same as the usual one for
gravitational waves. It is shown that the geon solution is a self-consistent
solution to Einstein's equations and that, to leading order, the equations
describing the geometry of the gravitational geon are identical to those
derived by Wheeler for the electromagnetic geon. An appendix provides an
existence proof for geon solutions to these equations.Comment: 18 pages, ReVTeX. To appear in Physical Review D. Significant changes
include more details in the derivations of certain key equations and the
addition of an appendix containing a proof of the existence of a geon
solution to the equations derived by Wheeler. Also a reference has been added
and various minor changes have been mad
Magnetic field of an in-plane vortex outside a layered superconductor
We present the solution to London's equations for the magnetic fields of a
vortex oriented parallel to the plane, and normal to a crystal face, of a
layered superconductor. These expressions account for flux spreading at the
superconducting surface, which can change the apparent size of the vortex along
the planes by as much as 30%. We compare these expressions with experimental
results.Comment: 13 pages, 5 figure
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