Engineering topics
Armstrong, J.
Publications and source records attributed to Armstrong, J..
Unequal-Arms Michelson Interferometers
Michelson interferometers allow phase measurements many orders of magnitude below the phase stability of the laser light injected into their two almost equal-length arms.
Search for Gravitational Wave Trains with the Spacecraft Ulysses
We report on the search for periodic gravitational wave in the mHz band conducted with the spacecraft ULYSSES. Gravitational wave signals generally provide information about the distance of the source; ULYSSES' data have a.
Search for Gravitational Wave Trains with the Spacecraft ULYSSES
We report on the search for periodic gravitational wave in the mHz band conducted with the spacecraft ULYSSES.
(abstract) System Performance of the Joint Galileo/Mars Observer/Ulysses 1993 Gravitational Wave Experiment
From March 21 to April 11, 1993, the Galileo, Mars Observer, and Ulysses spacecraft were tracked almost continuously in a coincidence experiment to search for low-frequency (~millihertz) gravitational radiation. We report here a first statistical assessment of the noise characteristics of the data, with particular attention to the performance of the radio science instrumentation itself.
Scattering by single ice needles and plates at 30 GHz
Because of the small loss tangent of ice at 30-50 GHz, significant depolarization of satellite-to-ground communication signals could occur due to the presence of cirrus clouds in their paths. It is known that cirrus clouds basically consist of ice needles and plates. Extensive calculations have been performed for the problem of scattering by a family of ice needles and plates for various length-to-width ratios ranging from 1 to 10. Scattering results with special attention to induced cross-polarized fields will be presented.
Computer measurement of arterial disease
Image processing technique quantifies human atherosclerosis by computer analysis of arterial angiograms. X-ray film images are scanned and digitized, arterial shadow is tracked, and several quantitative measures of lumen irregularity are computed. In other tests, excellent agreement was found between computer evaluation of femoral angiograms on living subjects and evaluation by teams of trained angiographers.