Testing for Year 2000 readiness: technical and management issues

The approach of the Year 2000 (Y2K) has called into question the condition of readiness of computer systems upon which organizations depend. Will these systems operate reliably after midnight, January 1, 2000, or will problems associated with date calculations cause failures that adversely affect users? This question has caused organizations to identify their critical systems, test these systems for Y2K problems, and take corrective action where necessary to ensure Y2K readiness. This paper examines various technical and management issues that Southwest Research Institute has dealt with in solving these problems     

A Far Infrared Photometer (FIRP) for the Infrared Telescope in Space (IRTS)

We describe the design and calibration of the Far-Infrared Photometer (FIRP), one of four focal plane instruments on the Infrared Telescope in Space (IRTS). The FIRP will provide absolute photometry in four bands centered at 150, 250, 400, and 700 μm with spectral resolution λ/Δλ ≈ 3 and spatial resolution ΔΘ = 0.5 degrees. High sensitivity is achieved by using bolometric detectors operated at 300 mK in an AC bridge circuit. The closed-cycle ³He refrigerator can be recycled in orbit. A 2 K shutter provides a zero reference for each field of view. More than 10% of the sky will be surveyed during the ≈3 week mission lifetime with a sensitivity of <10⁻¹³ W·cm⁻²·sr⁻¹ per 0.5 degree pixel.     

Symmetry and asymmetry of ionospheric weather at magnetic conjugate points for two midlatitude observatories

Variations of the ionospheric weather W-index for two midlatitude observatories, namely, Grahamstown and Hermanus, and their conjugate counterpart locations in Africa are studied for a period from October 2010 to December 2011. The observatories are located in the longitude sector, which has consistent magnetic equator and geographic equator so that geomagnetic latitudes of the line of force are very close to the corresponding geographic latitudes providing opportunity to ignore the impact of the difference of the gravitational field and the geomagnetic field at the conjugate points on the ionosphere structure and dynamics. The ionosondes of Grahamstown and Hermanus provide data of the critical frequency (foF2), and Global Ionospheric Maps (GIM) provide the total electron content (TECgps) along the magnetic field line up to the conjugate point in the opposite hemisphere. The global model of the ionosphere, International Reference Ionosphere, extended to the plasmasphere altitude of 20,200 km (IRI-Plas) is used to deliver the F2 layer peak parameters from TECgps at the magnetic conjugate area. The evidence is obtained that the electron gas heated by day and cooled by night at the summer hemisphere as compared with the opposite features in the conjugate winter hemisphere testifies on a reversal of plasma fluxes along the magnetic field line by the solar terminator. The ionospheric weather W-index is derived from NmF2 (related with foF2) and TECgps data. It is found that symmetry of W-index behavior in the magnetic conjugate hemispheres is dominant for the equinoxes when plasma movement along the magnetic line of force is imposed on symmetrical background electron density and electron content. Asymmetry of the ionospheric storm effects is observed for solstices when the plasma diffuse down more slowly into the colder winter hemisphere than into the warmer summer hemisphere inducing either plasma increase (positive phase) or decrease (negative phase of W-index) in the ionospheric and plasmaspheric plasma density.     

A Major Step in Series Regulators

Power hybrid microelectronic design techniques have been developed to satisfy the requirements of 10-ampere 100-watt series voltage regulators. Application of these new techniques has resulted in a package occupying roughly the same volume as a TO-63 power transistor, yet containing two 30-ampere power transistors, selectable external components, and associated control circuitry.