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Toric offset three-reflector antenna for an advanced microwave limb sounder

Richard E. Cofield, Thomas A. Cwik, Nasrat A. Raouf, Howard A. MacEwen
2002 Highly Innovative Space Telescope Concepts  
An advanced Microwave Limb Sounder (MLS), now in concept development for a potential future mission, is a space-borne heterodyne instrument to measure pressure, temperature, and atmospheric constituents from thermal emission between 120 and 2400 GHz. Previous MLS instruments used pencil-beam antennas sized to resolve N 1 vertical scale height. Current atmospheric models need better horizontal resolution than orbit spacing provides. To meet these needs, a new antenna concept combines the wide
more » ... n range of the parabolic torus with unblocked offset Cassegrain optics. The resulting system is diffraction-limited in the vertical plane but extremely astigmatic, with beamwidths 0.13~2.5". Nadir axis symmetry ensures that this Beam Aspect Ratio (BAR) is invariant over f33' of azimuth. The antenna can feed either an array of receivers or multiplexed low-noise receivers whose FOVs are swept by a small scanning mirror. We describe 3 stages of antenna design: First, using a paraxial-optics method, we choose conic profiles given vertical resolution orbit geometry, then develop the surfaces by nadir axis rotation, matching axisymmetric feeds to the BAR. A ray-trace program validates the design and generates alignment and deformation tolerances. Finally, a physical optics analysis verifies reflector surface currents and radiation patterns.
doi:10.1117/12.460463 fatcat:aiujjofhe5fihil6auum6kmpna

Calibration and performance validation of optical elements in a photoelastic modulator-based polarimetric camera

Anna-Britt Mahler, Russell Chipman, Stephen C. McClain, David J. Diner, Ab Davis, Nasrat Raouf, Sven Geier, Bruce Hancock
2008 IGARSS 2008 - 2008 IEEE International Geoscience and Remote Sensing Symposium  
As part of NASA's Instrument Incubator Program (IIP), we have been developing enabling technologies for the Multiangle SpectroPolarimetric Imager (MSPI), a candidate instrument for the Aerosol-Cloud-Ecosytem (ACE) mission. ACE is one of several satellite concepts identified in the 2007 National Research Council Earth Sciences Decadal Survey. MSPI is a multiangle, multispectral, high-accuracy polarization imager, and is envisioned to contain multiple cameras pointed at different viewing angles,
more » ... ith intensity imaging in several spectral bands between the ultraviolet and shortwave infrared, and accurate polarimetric imaging in a subset of the bands. To achieve a degree of linear polarization (DOLP) uncertainty of 0.5%, we temporally modulate the linear-polarization component of the incoming light at a rapid rate, enabling each detector within a focal-plane array-combined with polarization analyzers-to measure the relative proportions of the linear Stokes components Q or U to the total intensity I. Our system uses tandem photoelastic modulators (PEMs) within a reflective camera design. We report on the status of our prototype camera development, with particular emphasis on theoretical and experimental work on the required and measured performance of optical elements within the system including: the spectro-polarimetric filters, quarter wave plates, and tandem PEMs. We also report on the end-to-end measurement and calibration of camera polarization aberrations using a custom polarization state generator (PSG). Careful design and control of scattered light enables the PSG to generate polarization states between DOLP of 0.07% and 40% with an uncertainty of 0.05%, making it a precision tool for polarimetric calibration and validation of MSPI.
doi:10.1109/igarss.2008.4779400 dblp:conf/igarss/MahlerCMDDRGH08 fatcat:cdaol57wdjf2jev5fbm233ltf4

CDIM: Cosmic Dawn Intensity Mapper Final Report [article]

Asantha Cooray, Tzu-Ching Chang, Stephen Unwin, Michael Zemcov, Andrew Coffey, Patrick Morrissey, Nasrat Raouf, Sarah Lipscy, Mark Shannon, Gordon Wu, Renyue Cen, Ranga Ram Chary (+12 others)
2019 arXiv   pre-print
The Cosmic Dawn Intensity Mapper (CDIM) will transform our understanding of the era of reionization when the Universe formed the first stars and galaxies, and UV photons ionized the neutral medium. CDIM goes beyond the capabilities of upcoming facilities by carrying out wide area spectro-imaging surveys, providing redshifts of galaxies and quasars during reionization as well as spectral lines that carry crucial information on their physical properties. CDIM will make use of unprecedented
more » ... vity to surface brightness to measure the intensity fluctuations of reionization on large-scales to provide a valuable and complementary dataset to 21-cm experiments. The baseline mission concept is an 83-cm infrared telescope equipped with a focal plane of 24 × 20482 detectors capable of R = 300 spectro-imaging observations over the wavelength range of 0.75 to 7.5 μm using Linear Variable Filters (LVFs). CDIM provides a large field of view of 7.8 deg2 allowing efficient wide area surveys, and instead of moving instrumental components, spectroscopic mapping is obtained through a shift-and-stare strategy through spacecraft operations. CDIM design and capabilities focus on the needs of detecting faint galaxies and quasars during reionization and intensity fluctuation measurements of key spectral lines, including Lyman-α and Hα radiation from the first stars and galaxies. The design is low risk, carries significant science and engineering margins, and makes use of technologies with high technical readiness level for space observations.
arXiv:1903.03144v2 fatcat:h6ibgykdwjdipmeevkvucxq554


2019 2019 21st International Middle East Power Systems Conference (MEPCON)  
Solar-Wind Distributed Generations in Distribution Networks Considering the Uncertainty Using Grasshopper Optimization Algorithm . . . . . . . 406 Ashraf Ramadan, Mohamed Ebeed, Salah Kamel and Loai Nasrat  ...  and Grid Connection Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 790 Yehia Abdelrehim, Mohamed Abdul Raouf  ... 
doi:10.1109/mepcon47431.2019.9008153 fatcat:hrn2ik5wsfdl7fqetffeq7pvpy

TPF-I Planet Detection Testbed: Progress in Testing Exo-planet Signal Detection

S. R. Martin, P. Szwaykowski, F. M. Loya
2005 Proceedings of the International Astronomical Union  
Raouf.  ...  Acknowledgements The authors would like to acknowledge the contributions of the other members of the testbed team: Kurt Liewer, Hong Tang, Randall Bartos, Steve Monacos, Raymond Lam, Boris Lurie and Nasrat  ... 
doi:10.1017/s1743921306009458 fatcat:htlxjsobufh7phxwob4lgktkxq

Quality of Maternal Death Documentation in Afghanistan: A Retrospective Health Facility Record Review

Farzana Maruf, Hannah Tappis, Jelle Stekelenburg, Thomas van den Akker
2021 Frontiers in Global Women's Health  
Thanks to the study team members Nasrat Ansari, Faridullah Atiqzai, Partamin Manali, Zahra Sultani, Sayed Esmati, Ahmad Eklil Husain, Mahmood Azimi, Enayatullah Mayar, Abdul Qader Rahimi, Raouf Saidzadah  ... 
doi:10.3389/fgwh.2021.610578 pmid:34816182 pmcid:PMC8593965 fatcat:m2gxvlfegbditipwidiyxsa7bi

Multi-bandgap high efficiency converter (RAINBOW)

C.R. Lewis, W.M. Phillips, V.B. Shields, P.M. Stella, I. Bekey
IECEC-97 Proceedings of the Thirty-Second Intersociety Energy Conversion Engineering Conference (Cat. No.97CH6203)  
Raouf and Mark Underwood (JPL), and John Grievenkarnp (University of Arizona).  ...  California Institute of Technology, under contract with tie National Aeronautics and Space Adminiskation The authors would like to acknowledge the excellent scientific and engineering contributions of Nasrat  ... 
doi:10.1109/iecec.1997.659222 fatcat:6rkfqolijfhuxo5k6c73n5h7ja

Exploration of a Polarized Surface Bidirectional Reflectance Model Using the Ground-Based Multiangle SpectroPolarimetric Imager

David Diner, Feng Xu, John Martonchik, Brian Rheingans, Sven Geier, Veljko Jovanovic, Ab Davis, Russell Chipman, Stephen McClain
2012 Atmosphere  
Raouf, and Chris Wrigley for instrument engineering; and Michael Bull for data processing.  ...  Anna-Britt Mahler and Karlton Crabtree for assistance with the design, assembly and test of GroundMSPI; Ghobad Saghri and Amy Wu for assistance in collecting the GroundMSPI data; Gary Gutt, Bruce Hancock, Nasrat  ... 
doi:10.3390/atmos3040591 fatcat:xipv2yaanzccxmhlycv7eugih4

Demonstration of exoplanet detection using an infrared telescope array

S. R. Martin, A. J. Booth
2010 Astronomy and Astrophysics  
Raouf (optics), Piotr Szwaykowski (optical engineering), Randall Bartos (engineering), Boris Lurie (controls systems), Santos "Felipe" Fregoso (software), Francisco Aguayo (engineering), Martin Marcin  ...  in the exoplanet field by current telescope technologies, the eventual characterization of Earth-like exoplanets will depend on high performance observatories such as TPF-I and Darwin. years including Nasrat  ... 
doi:10.1051/0004-6361/201014942 fatcat:eufcf7vemffkrbdw4q2pjubxgm

العدد کامل (ابريل)

2022 مجلة دراسات الطفولة  
ë Ði @ †îÏì× @ QY @Z òa‰… @ Ýîܤ @ bnîß @ òß †Ôß Manifestations and neurological complications of COVID 19 in pediatric patients: A Meta-Analysis study (1) Basma Hossam (1) Pof.Randa Kamal Abdel Raouf  ...  Intelligence Scale, the fifth Edition (SB5) (Arabization: Safwat Farag, 2011), Scale of the Socio-Economic and Cultural Level (by Mohamed Saafan and Doaa Khattab, 2016), and The Scale of Dyslexia (by Nasrat  ... 
doi:10.21608/jsc.2022.251524 fatcat:vzue5oilfrbqdiew2fw3uh5f6e