Scale Factor Correction Research Articles

Compensation for surface contamination in a D-fiber evanescent wave methane sensor

The effects of surface contamination on the performance of a D-fiber evanescent wave methane sensor are discussed. Contamination on the flat surface of the D-fiber will modify both the scale factor of the methane detection system and the birefringence of the D-fiber. The birefringence variation can be monitored and used to compensate for the scale factor variation, through one of the two compensation models which will be described in the text. The models are found to be fairly accurate, and for the D-fiber used in our experimental tests, the maximum relative error for scale factor correction is about /spl plusmn/5%, for both models.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A global scale factor in brain topography.

In this paper statistical resampling techniques are used to support the presence of an equiangular first principal component in EEG log spectra and therefore the existence of a global scale factor in EEG recordings. the Log transformed spectra from a normal sample (n = 211, age 5-97) were analyzed. To reach this conclusion a method for estimating the scale factor is introduced. It is also shown that this factor remains constant in each individual for all derivations and frequencies and across functional states. The contribution of this scale factor to the overall variance of the normal EEG reaches 42% of the total variance of age corrected data. Part of the variance of the scale factor exhibits age dependency. Scale factor correction of EEG spectra data improves the diagnostic accuracy for detecting pathological EEG spectra from an almost random level (Area under the ROC curve = .6) to .84.

The 1987 Southeastern Alaska Gravity Calibration Range: Absolute and relative gravity measurements

In June 1987 a gravimeter calibration range was set up in southeastern Alaska and the Yukon territory, as part of a geophysical determination of the Newtonian gravitational constant. Absolute gravity measurements were made between the range endpoints using the Institute of Geophysics and Planetary Physics absolute gravity meter. The calibration range spans 171.841±0.014 mGal, with a midpoint g value of 9.81746500 ms−2. Relative gravity meters, including a LaCoste and Romberg borehole gravity meter, were read along this range. A scale factor correction (SFC) for borehole meter 14 was found to be (8.1 ± 1.5) × 10−4, and for meter G‐349 the correction was (−3.3 ± 1.7) × 10−4. The SFC for meter D‐85 has an upper bound of ±1.0 × 10−4.

Temperature structure in the lower atmosphere of Venus: New results derived from pioneer Venus entry probe measurements

The Pioneer Venus Small-Probe Net Flux Radiometer temperature sensor and its calibration, the thermal model of the sensor head, the procedure for deriving atmospheric temperature from the sensor temperatures, and the new temperature results for each entry probe are reported. The new results are compared with those of the Small-Probe Atmospheric Structure experiment and with simple models of diurnal and latitudinal temperature contrasts. A dynamical inconsistency between these results and low-latitude measurements by the Sounder probe is described, and possible ways to resolve it are considered.

Positive scale factor correction in the laser gyro

Unlike what was expected, a measurement of the scale factor in the laser gyro as a function of rotation showed it to increase with decreasing rate. At low rates the scale factor peaked and then rapidly dropped to zero at the lock-in threshold. The height of the maximum was found to increase and the width to decrease with operation of the laser closer to lasing threshold. The height varied between 0.003 and 0.3 percent of the nominal scale factor and the half-width varied between 5 and 45 deg/s. A theoretical description of the results was obtained in the asymptotic limit of rates high compared to the lock-in threshold. The shape of the scale factor curve was found to be Lorentzian with a width proportional to the excess gain. The sign of the scale factor correction was found to be due to the phasing of the backscattering, which is the source of the lock-in. This phasing was found to be consistent with the observed 180-deg phasing between the ac components of each beam when the laser is unlocked.

Power-dependent scale-factor correction in the laser gyro

Power-dependent scale-factor correction in the laser gyro