The automated data processing pipelines for SIRTF IRS
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SIRTF IRS Infrared Spectrograph mission design↗
Engineering topics
Khan, I.
Publications and source records attributed to Khan, I..
P32Tools: reduction of ISOPHOT P32 oversampled maps
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ISO↗
P32Tools: reduction of ISOPHOT P32 oversampled maps
During the IS0 mission, the ISOPHOT instrument has collected more than 1100 observations in oversampled mapping mode (AOT PHT32) in the wavelength range of45 to 240 microns. The observations comprise mapping of small and large extended regions, but also faint point sources. PHT32 observations are affected by strong signal transients due to flux changes generated by the relatively fast chopper movement. A program described by Tuffs & Gabriel (2002), was developed to correct for these effects. It was integrated in the ISOPHOT Interactive Analysis (PIA) via a graphical user interface (GUI), so that most aspects of the processing can be addressed in a coherent and user friendly environment. The resulting package 'P32Tools' was introduced to the user community at three hands-on workshops on PHT32 processing held in spring 2001. The hands-on experience from these workshops lead to further improvements. Here we present an overview of the functionalities of the final release of this new software.
ISOPHOT oversampled mapping ISOPHOT Interactive An↗
Vibration Method for Tracking the Resonant Mode and Impedance of a Microwave Cavity
There has been a concerted effort to improve the microwave heating technique for processing materials at high temperature. Improved optimization of the energy transfer from a microwave source to the material being processed is required. A vibration technique is pre- sented to continuously maintain a mode resonance and impedance match between a constant frequency magnetron source and a resonant cavity.
microwave↗
Vibration Method for Tracking the Resonant Mode and Impedance of a Microwave Cavity
A vibration technique his been developed to continuously maintain mode resonance and impedance much between a constant frequency magnetron source and resonant cavity. This method uses a vibrating metal rod to modulate the volume of the cavity in a manner equivalent to modulating an adjustable plunger. A similar vibrating metal rod attached to a stub tuner modulates the waveguide volume between the source and cavity. A phase sensitive detection scheme determines the optimum position of the adjustable plunger and stub turner during processing. The improved power transfer during the heating of a 99.8% pure alumina rod was demonstrated using this new technique. Temperature-time and reflected power-time heating curves are presented for the cases of no tracking, impedance tracker only, mode tracker only and simultaneous impedance and mode tracking. Controlled internal melting of an alumina rod near 2000 C using both tracking units was also demonstrated.
Barmatz, M.↗
(abstract) Vibration Method for Tracking the Resonant Mode and Impedance of a Microwave Cavity
We have developed a vibration technique to continuously maintain mode resonance and impedance match between a constant frequency magnetron source and resonant cavity. This method uses a vibrating metal rod to modulate the volume of the cavity that is equivalent to modulating an adjustable plunger. A similar vibrating metal rod attached to a stub tuner modulates the waveguide volume between the source and cavity. A phase sensitive detection scheme determines the optimum position of the adjustable plunger and stub tuner. The improved power transfer during the heating of a 99.8% pure alumina rod was demonstrated using this new technique. Temperature-time and reflected power-time plotswill be presented for the cases of no tracking, impedance tracker only, mode tracker only, and simultaneous impedance and mode tracking. Internal melting of the alumina rod near 2000°C with both trackers on will also be discussed.
microwave↗
Progress report
The NASA funding allowed Clark Atlanta University (CAU) to establish a High Performance Polymers And Ceramics (HiPPAC) Research Center. The HiPPAC Center is consolidating and expanding the existing polymer and ceramic research capabilities at CAU through the development of interdepartmental and interinstitutional research in: (1) polymer synthesis; (2) polymer characterization and properties; (3) polymer processing; (4) polymer-based ceramic synthesis; and (5) ceramic characterization and properties. This Center has developed strong interactions between scientists and materials scientists of CAU and their counterparts from sister institutions in the Atlanta University Center (AUC) and the Georgia Institute of Technology. As a component of the center, we have started to develop strong collaborations with scientists from other universities and the HBCU's, national and federal agency laboratories, and the private sector during this first year. During this first year we have refined the focus of the research in the HiPPAC Center to three areas with seven working groups that will start programmatic activities on January 1, 1993, as follows: (1) nonlinear optical properties of chitosan derivatives; (2) polymeric electronic materials; (3) nondestructive characterization and prediction of polyimide performance; (4) solution processing of high-performance materials; (5) processable polyimides for composite applications; (6) sol-gel based ceramic materials processing; and (7) synthetic based processing of pre-ceramic polymers.
Abhiraman, A.↗
Deformable subreflector computed by geometric optics
Using a Cassegrainian geometry, the 64-meter antenna with its distorted paraboloidal reflecting surface is forced to produce a uniform phase wavefront by a pathlength-compensating subreflector. First, the computed distortion vectors at the joints or nodes of the main reflector structure supporting the surface panels are best fitted to a paraboloid. Second, the resulting residual distortion errors are used to determine a compensating subreflector surface by ray tracing using geometric optics principles. Third, the totally corrected subreflector surface is defined by the normal directions and distances to the surface of the original symmetric hyperboloid for the purpose of evaluation. Finally, contour maps of distortions of the paraboloid reflector and the compensating subreflector are presented. A field-measured check of the subreflector in focused position as computed by the described methodology is also presented for the antenna position at horizon look with the geometry at 45 degrees elevation.
Katow, M. S.↗
The singly averaged differential equations of satellite motion for e greater than or equal to 0 and less than 1
The singly-averaged differential equations of motion of a satellite are developed in terms of parameters valid for all eccentricities less than one. The perturbations included in the acceleration model are due to an aspherical central planet (zonal harmonics up to degree 20 and resonant harmonics up to degree and order 20), atmospheric drag for a time-varying atmosphere, third-body gravity (the sun and moon for an earth satellite), solar radiation pressure with shadowing, and impulsive maneuvers. Analytic averaging is used to remove short-period terms due to the aspherical central planet and third-body gravity. Numerical averaging is used to remove short-period terms due to atmospheric drag and solar radiation pressure.
Dallas, S. S.↗