2,831 to 2,840 of 2,910 Results
Dec 20, 2004
Pravdo, Steven H.; Shaklan, Stuart B.; Henry, Todd; Benedict, G. Fritz, 2004, "Astrometric Discovery of GJ 164B", https://hdl.handle.net/2014/40831, The Astrophysical Journal, 617:1323–1329, doi.org/10.1086/425653, JPL Open Repository
We discovered a low-mass companion to the M dwarf GJ 164 with the CCD-based imaging system of the Stellar Planet Survey astrometric program. The existence of GJ 164B was confirmed with Hubble Space Telescope NICMOS imaging observations. A high-dispersion spectral observation in V... |
Dec 13, 2004
Bloemhof, E. E.; Wallace, J. K., 2004, "Simple broadband implementation of a phase contrast wavefront sensor for adaptive optics", https://hdl.handle.net/2014/39297, Optics Express, Vol. 12, Iss 25, pp 6240-6245, (2004), doi: 10.1364/OPEX.12.006240, JPL Open Repository
The most critical element of an adaptive optics system is its wavefront sensor, which must measure the closed-loop difference between the corrected wavefront and an ideal template at high speed, in real time, over a dense sampling of the pupil. Most high-order systems have used S... |
Dec 6, 2004
Becker, Heidi N.; Johnston, Allan H., 2004, "Dark current degradation of near infrared avalanche photodiodes from proton irradiation", https://hdl.handle.net/2014/41121, IEEE Transactions On Nuclear Science, Vol. 51, No. 6, December 2004, doi:10.1109/TNS.2004.839165, JPL Open Repository
InGaAs and Ge avalanche photodiodes (APDs) are examined for the effects of 63-MeV protons on dark current. Dark current increases were large and similar to prior results for silicon APDs, despite the smaller size of InGaAs and Ge devices. Bulk dark current increases from displace... |
Dec 6, 2004
Stoica, Adrian; Keymeulen, Didier; Arslan, Tughrul; Duong, Vu; Zebulum, Ricardo; Ferguson, Ian; Guo, Xin, 2004, "Self-recovery experiments in extreme environments using a field programmable transistor array", https://hdl.handle.net/2014/41672, 2004 IEEE International Conference on Field-Programmable Technology, 2004. Proceedings., Page(s): 9 - 15 , DOI: 10.1109/FPT.2004.1393245, JPL Open Repository
Temperature and radiation tolerant electronics, as well as long life survivability are key capabilities required for future NASA missions. Current approaches to electronics for extreme environments focus on component level robustness and hardening. However, current technology can... |
Dec 1, 2004
Irom, Farokh; Farmanesh, F. F., 2004, "Frequency dependence of single-event upset in advanced commercial PowerPC microprocessors", https://hdl.handle.net/2014/41132, IEEE Transactions on Nuclear Science, Vol. 51, No. 6, p. 3505-3509, December 2004, JPL Open Repository
Single-event upset (SEU) from heavy ions is measured for advanced commercial microprocessors in a dynamic mode with clock frequencies up to 1 GHz. Frequency and core voltage dependence of SEUs in registers and D-Cache are discussed. The results of our studies suggest the SEU in r... |
Dec 1, 2004
Weisbin, Charles R.; Rodriguez, Guillermo; Alberto, Elfes; Smith, Jeffrey H., 2004, "Toward a systematic approach for selection of NASA technology portfolios", https://hdl.handle.net/2014/40872, Systems Engineering, Volume 7 , Issue 4 (December 2004), DOI 10.1002/sys.20010, JPL Open Repository
There is an important need for a consistent analytical foundation supporting the selection and monitoring of R&D tasks that support new system concepts that enable future NASA missions. This capability should be applicable at various degrees of abstraction, depending upon whether... |
Nov 29, 2004
Abbasfar, Aliazam; Divsalar, Dariush; Yao, Kung, 2004, "Accumulate repeat accumulate codes", https://hdl.handle.net/2014/38834, ISIT 2004, Chicago, USA, June 27 – July 2, 2004, JPL Open Repository
In this paper we propose an innovative channel coding scheme called “Accumulate Repeat Accumulate codes” (ARA). This class of codes can be viewed as serial turbo-like codes, or as a subclass of Low Density Parity Check (LDPC) codes, thus belief propagation can be used for iterati... |
Nov 25, 2004
Wu, Dong L.; Zhang, Fuqing, 2004, "A study of mesoscale gravity waves over the North Atlantic with satellite observations and a mesoscale model", https://hdl.handle.net/2014/40889, Journal Of Geophysical Research, Vol. 109, D22104, doi:10.1029/2004JD005090, 2004, JPL Open Repository
Satellite microwave data are used to study gravity wave properties and variabilities over the northeastern United States and the North Atlantic in the December–January periods. The gravity waves in this region, found in many winters, can reach the tratopause with growing amplitud... |
Nov 20, 2004
Sánchez Contreras, C.; Gil de Paz, A.; Sahai, R., 2004, "The companion to the central mira star of the Protoplanetary Nebula OH 231.8+4.2", https://hdl.handle.net/2014/40827, Astrophysical Journal, 616:519–524, 2004 November 20, doi.org/10.1086/424827, JPL Open Repository
We present deep optical long-slit spectra of the peculiar protoplanetary nebula (PPN) OH 231.8+4.2 obtained with the 6.5 m Baade Telescope at Las Campanas Observatory (Chile). In addition to the molecular absorption bands characteristic of the M9-10 III star inside OH 231.8+4.2 (... |
Nov 13, 2004
Smrekar, S. E.; McGill, G. E.; Raymond, C. A.; Dimitriou, A. M., 2004, "Geologic evolution of the Martian dichotomy in the Ismenius area of Mars and implications for plains magnetization", https://hdl.handle.net/2014/40840, Journal of Geophysical Research, Vol. 109, E11002, doi:10.1029/2004JE002260, 2004, JPL Open Repository
The origin of the Martian dichotomy, which divides highlands from lowlands, is unknown. We examine a section of the dichotomy ( 50 - 90E) defined by steep scarps and normal faults. Stratigraphy and age relationships preclude the formation of the 2.5 km high boundary via erosion.... |
