Independent Orbiter Assessment (IOA): Analysis of the DPS subsystem

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis/Critical Items List (FMEA/CIL) is presented. The IOA approach features a top-down analysis of the hardware to independently determine failure modes, criticality, and potential critical items. The independent analysis results corresponding to the Orbiter Data Processing System (DPS) hardware are documented. The DPS hardware is required for performing critical functions of data acquisition, data manipulation, data display, and data transfer throughout the Orbiter. Specifically, the DPS hardware consists of the following components: Multiplexer/Demultiplexer (MDM); General Purpose Computer (GPC); Multifunction CRT Display System (MCDS); Data Buses and Data Bus Couplers (DBC); Data Bus Isolation Amplifiers (DBIA); Mass Memory Unit (MMU); and Engine Interface Unit (EIU). The IOA analysis process utilized available DPS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode. Due to the extensive redundancy built into the DPS the number of critical items are few. Those identified resulted from premature operation and erroneous output of the GPCs

Independent Orbiter Assessment (IOA): Analysis of the guidance, navigation, and control subsystem

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) is presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results corresponding to the Orbiter Guidance, Navigation, and Control (GNC) Subsystem hardware are documented. The function of the GNC hardware is to respond to guidance, navigation, and control software commands to effect vehicle control and to provide sensor and controller data to GNC software. Some of the GNC hardware for which failure modes analysis was performed includes: hand controllers; Rudder Pedal Transducer Assembly (RPTA); Speed Brake Thrust Controller (SBTC); Inertial Measurement Unit (IMU); Star Tracker (ST); Crew Optical Alignment Site (COAS); Air Data Transducer Assembly (ADTA); Rate Gyro Assemblies; Accelerometer Assembly (AA); Aerosurface Servo Amplifier (ASA); and Ascent Thrust Vector Control (ATVC). The IOA analysis process utilized available GNC hardware drawings, workbooks, specifications, schematics, and systems briefs for defining hardware assemblies, components, and circuits. Each hardware item was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode

Selective Cheat (Bromus secalinus) Control in Wheat (Triticum aestivum) with Atrazine

Eleven field experiments were conducted to evaluate atrazine for selective cheat control in hard red winter wheat. Cheat control with atrazine at 140 glha applied PRE varied from 5 to 83% but was similar to cheat control with the standard treatment, triasulfuron at 29 glha. Control with atrazine at 280, 560, and 840 glha applied early POST exceeded control with the standard treatment, triasulfuron plus metribuzin at 29 plus 157 glha, in one, three, and five experiments, respectively. Metribuzin at 420 glha was the standard treatment for cheat control in tillered wheat and controlled cheat 28 to 96%. Cheat control with atrazine at 560 and 840 glha applied to tillered wheat was comparable to or exceeded the standard. Of the early POST treatments the standard increased yield in three of five experiments. Triasulfuron plus atrazine applied POST at 29 plus 280 glha also increased wheat yield in three offive experiments and yields did not differ from the standard treatment at the other two experiments. In on-farm experiments, cheat control with atrazine at 560 glha was similar to control with metribuzin at 420 glha in two of three experiments. In these experiments five of six treatments of metribuzin at 420 glha increased yield and four of six treatments of atrazine at 560 glha increased yield. In cultivar tolerance experiments the metribuzin tolerant cultivars 'TAM W -101' and '2180' were much more severely injured by atrazine applied POST at 840 glha than 'Karl 92', a cultivar considered less tolerant to metribuzin. Nomenclature: Atrazine,6-chloroN- ethyl-N' -(l-methylethyl)-l, 3, 5, -triazine-2, 4-diamine~ metribuzin, 4-amino-6-( 1, 1- dimethylethy)-3-(methylthio )-1, 2, 4-triazin-5( 4H)-one; triasulfuron, 2-(2-chloroethoxy)N-[[ (4-methoxy-6-methyl-1, 3, 5-triazin-2-yl)amino ]carbonyl]-benzenesulfonamide; cheat, Bromus secalinus L. #3, BROSE; wheat, Triticum aestivum L. Additional index words: Metribuzin, triasulfuron, BROSE,

High Velocity Cloud Complex H: A Satellite of the Milky Way in a Retrograde Orbit?

Observations with the Green Bank Telescope of 21cm HI emission from the high-velocity cloud Complex H suggest that it is interacting with the Milky Way. A model in which the cloud is a satellite of the Galaxy in an inclined, retrograde circular orbit reproduces both the cloud's average velocity and its velocity gradient with latitude. The model places Complex H at approximately 33 kpc from the Galactic Center on a retrograde orbit inclined about 45 degrees to the Galactic plane. At this location it has an HI mass > 6 10^6 Msun and dimensions of at least 10 by 5 kpc. Some of the diffuse HI associated with the cloud has apparently been decelerated by interaction with Galactic gas. Complex H has similarities to the dwarf irregular galaxy Leo A and to some compact high-velocity clouds, and has an internal structure nearly identical to parts of the Magellanic Stream, with a pressure P/k about 100 cm^{-3} K.Comment: 12 pages includes 4 figures. To be published in Astrophysical Journal Letters, 1 July 200

Contaminant Levels in Eggs of American White Pelicans, Pelecanus erythrorhynchos, from Chase Lake, North Dakota

American White Pelicans (Pelecanus erythrorhynchos) are colonial nesters, making them susceptible to site-specific mortality factors. One of the largest known breeding colonies is at Chase Lake National Wildlife Refuge in North Dakota. In 2004, this colony suffered total reproductive failure. In 2005, we collected abandoned eggs from this colony to test for environmental contaminants. Nine eggs were analyzed for 28 organochlorine pesticides, total polychlorinated biphenyls, and 26 inorganic elements. Based on concentrations in this sample of eggs and levels linked to reproductive problems in birds, adult pelicans in the Chase Lake breeding colony are not at known risk from any of the environmental contaminants we measured

Discovery of a New Deeply Eclipsing SU UMa-Type Dwarf Nova, IY UMa (= TmzV85)

We discovered a new deeply eclipsing SU UMa-type dwarf nova, IY UMa, which experienced a superoutburst in 2000 January. Our monitoring revealed two distinct outbursts, which suggest a superoutburst interval of ~800 d, or its half, and an outburst amplitude of 5.4 mag. From time-series photometry during the superoutburst, we determined a superhump and orbital period of 0.07588 d and 0.0739132 d, respectively.Comment: 5 pages, 3 figures, accepted by PASJ lette

HS 2325+8205 - an ideal laboratory for accretion disk physics

We identify HS 2325+8205 as an eclipsing, frequently outbursting dwarf nova with an orbital period of 279.841731(5) min. Spectroscopic observations are used to derive the radial velocity curve of the secondary star from absorption features and also from the H-alpha emission lines, originating from the accretion disc, yielding K_secondary = K_abs = 237 +- 28 km/s and K_emn = 145 +- 9 km/s respectively. The distance to the system is calculated to be 400 (+200, -140) pc. A photometric monitoring campaign reveals an outburst recurrence time of 12-14 d, The combination of magnitude range (17-14 mag), high declination, eclipsing nature and frequency of outbursts makes HS 2325+8205 the ideal system for "real-time" studies of the accretion disc evolution and behavior in dwarf nova outbursts.Comment: 20 pages, 7 figures. Accepted for Publications of the Astronomical Society of the Pacifi