15,954 research outputs found
Alumina bearing in gas-lubricated gyros
Friction and wear properties of alumina bearings for use in gas-lubricated gyroscope
Independent Orbiter Assessment (IOA): FMEA/CIL assessment
The McDonnell Douglas Astronautics Company (MDAC) was selected to perform an Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL). Direction was given by the Orbiter and GFE Projects Office to perform the hardware analysis and assessment using the instructions and ground rules defined in NSTS 22206. The IOA analysis featured a top-down approach to determine hardware failure modes, criticality, and potential critical items. To preserve independence, the analysis was accomplished without reliance upon the results contained within the NASA and Prime Contractor FMEA/CIL documentation. The assessment process compared the independently derived failure modes and criticality assignments to the proposed NASA post 51-L FMEA/CIL documentation. When possible, assessment issues were discussed and resolved with the NASA subsystem managers. Unresolved issues were elevated to the Orbiter and GFE Projects Office manager, Configuration Control Board (CCB), or Program Requirements Control Board (PRCB) for further resolution. The most important Orbiter assessment finding was the previously unknown stuck autopilot push-button criticality 1/1 failure mode. The worst case effect could cause loss of crew/vehicle when the microwave landing system is not active. It is concluded that NASA and Prime Contractor Post 51-L FMEA/CIL documentation assessed by IOA is believed to be technically accurate and complete. All CIL issues were resolved. No FMEA issues remain that have safety implications. Consideration should be given, however, to upgrading NSTS 22206 with definitive ground rules which more clearly spell out the limits of redundancy
Massive relic neutrinos in the galactic halo and the knee in the cosmic ray spectrum
Despite many efforts to find a reasonable explanation, the origin of the
"knee" in the cosmic ray spectrum at energy around 10**15.5 eV remains
mysterious. In this letter we suggest that the "knee" may be due to a GZK-like
effect of cosmic rays interacting with massive neutrinos in the galactic halo.
Simple kinematics connects the location of the "knee" with the mass of the
neutrinos, and, while the required interaction cross section is larger than
that predicted by the Standard Model, it can be accommodated by a small
neutrino magnetic dipole moment. The values for the neutrino parameters
obtained from the analysis of existing experimental data are compatible with
present laboratory bounds.Comment: 8 pages, 1 figure, uses RevTe
Variable Dynamic Force Vector Rocket Test Apparatus
Design and performance characteristics of variable dynamic force vector rocket test apparatu
Layered classification techniques for remote sensing applications
The layered classifier method is outlined and several applications to pattern classification for which the approach is suited are discussed
Independent Orbiter Assessment (IOA): FMEA/CIL assessment
The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. Direction was given by the Orbiter and GFE Projects Office to perform the hardware analysis and assessment using the instructions and ground rules defined in NSTS 22206. The IOA analysis features a top-down approach to determine hardware failure modes, criticality, and potential critical items. To preserve independence, the anlaysis was accomplished without reliance upon the results contained within the NASA and prime contractor FMEA/CIL documentation. The assessment process compares the independently derived failure modes and criticality assignments to the proposed NASA Post 51-L FMEA/CIL documentation. When possible, assessment issues are discussed and resolved with the NASA subsystem managers. The assessment results for each subsystem are summarized. The most important Orbiter assessment finding was the previously unknown stuck autopilot push-button criticality 1/1 failure mode, having a worst case effect of loss of crew/vehicle when a microwave landing system is not active
Notes on Urban Research in the USSR
I am taking the unusual step of circulating as a Working Paper some notes of discussions with Soviet colleagues held here over the last two weeks. The reasons for so doing are (a) the new light Prof. Avdotjin threw on the process of investment in urban research in the U.S.S.R., and (b) keeping my colleagues updated on research plans of the IIASA Urban Project
Numerical Construction of Likelihood Distributions and the Propagation of Errors
The standard method for the propagation of errors, based on a Taylor series expansion, is approximate and frequently inadequate for realistic problems. A simple and generic technique is described in which the likelihood is constructed numerically, thereby greatly facilitating the propagation of errors
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