171,775 research outputs found
Effects of liquid slosh on rendezvous dynamics
Mathematical model using Euler-Lagrange equation to investigate liquid slosh effects on rendezvous dynamic
Development and evaluation of a fault-tolerant multiprocessor (FTMP) computer. Volume 1: FTMP principles of operation
The basic organization of the fault tolerant multiprocessor, (FTMP) is that of a general purpose homogeneous multiprocessor. Three processors operate on a shared system (memory and I/O) bus. Replication and tight synchronization of all elements and hardware voting is employed to detect and correct any single fault. Reconfiguration is then employed to repair a fault. Multiple faults may be tolerated as a sequence of single faults with repair between fault occurrences
Development and evaluation of a fault-tolerant multiprocessor (FTMP) computer. Volume 4: FTMP executive summary
The FTMP architecture is a high reliability computer concept modeled after a homogeneous multiprocessor architecture. Elements of the FTMP are operated in tight synchronism with one another and hardware fault-detection and fault-masking is provided which is transparent to the software. Operating system design and user software design is thus greatly simplified. Performance of the FTMP is also comparable to that of a simplex equivalent due to the efficiency of fault handling hardware. The FTMP project constructed an engineering module of the FTMP, programmed the machine and extensively tested the architecture through fault injection and other stress testing. This testing confirmed the soundness of the FTMP concepts
Development and evaluation of a Fault-Tolerant Multiprocessor (FTMP) computer. Volume 2: FTMP software
The software developed for the Fault-Tolerant Multiprocessor (FTMP) is described. The FTMP executive is a timer-interrupt driven dispatcher that schedules iterative tasks which run at 3.125, 12.5, and 25 Hz. Major tasks which run under the executive include system configuration control, flight control, and display. The flight control task includes autopilot and autoland functions for a jet transport aircraft. System Displays include status displays of all hardware elements (processors, memories, I/O ports, buses), failure log displays showing transient and hard faults, and an autopilot display. All software is in a higher order language (AED, an ALGOL derivative). The executive is a fully distributed general purpose executive which automatically balances the load among available processor triads. Provisions for graceful performance degradation under processing overload are an integral part of the scheduling algorithms
Cloud cover estimation: Use of GOES imagery in development of cloud cover data base for insolation assessment
The potential of using digital satellite data to establish a cloud cover data base for the United States, one that would provide detailed information on the temporal and spatial variability of cloud development are studied. Key elements include: (1) interfacing GOES data from the University of Wisconsin Meteorological Data Facility with the Jet Propulsion Laboratory's VICAR image processing system and IBIS geographic information system; (2) creation of a registered multitemporal GOES data base; (3) development of a simple normalization model to compensate for sun angle; (4) creation of a variable size georeference grid that provides detailed cloud information in selected areas and summarized information in other areas; and (5) development of a cloud/shadow model which details the percentage of each grid cell that is cloud and shadow covered, and the percentage of cloud or shadow opacity. In addition, comparison of model calculations of insolation with measured values at selected test sites was accomplished, as well as development of preliminary requirements for a large scale data base of cloud cover statistics
Recent developments in the application of risk analysis to waste technologies.
The European waste sector is undergoing a period of unprecedented change driven
by business consolidation, new legislation and heightened public and government
scrutiny. One feature is the transition of the sector towards a process industry
with increased pre-treatment of wastes prior to the disposal of residues and the
co-location of technologies at single sites, often also for resource recovery
and residuals management. Waste technologies such as in-vessel composting, the
thermal treatment of clinical waste, the stabilisation of hazardous wastes,
biomass gasification, sludge combustion and the use of wastes as fuel, present
operators and regulators with new challenges as to their safe and
environmentally responsible operation. A second feature of recent change is an
increased regulatory emphasis on public and ecosystem health and the need for
assessments of risk to and from waste installations. Public confidence in waste
management, secured in part through enforcement of the planning and permitting
regimes and sound operational performance, is central to establishing the
infrastructure of new waste technologies. Well-informed risk management plays a
critical role. We discuss recent developments in risk analysis within the sector
and the future needs of risk analysis that are required to respond to the new
waste and resource management agenda
ATMOS Spacelab 1 science investigation
Existing infrared spectra from high speed interferometer balloon flights were analyzed and experimental analysis techniques applicable to similar data from the ATMOS experiment (Spacelab 3) were investigated. Specific techniques under investigation included line-by-line simulation of the spectra to aid in the identification of absorbing gases, simultaneous retrieval of pressure and temperature profiles using carefully chosen pairs of CO2 absorption lines, and the use of these pressures and temperatures in the retrieval of gas concentration profiles for many absorbing species. A search for a new absorption features was also carried out, and special attention was given to identification of absorbing gases in spectral bandpass regions to be measured by the halogen occultation experiment
Research on computer aided testing of pilot response to critical in-flight events
Experiments on pilot decision making are described. The development of models of pilot decision making in critical in flight events (CIFE) are emphasized. The following tests are reported on the development of: (1) a frame system representation describing how pilots use their knowledge in a fault diagnosis task; (2) assessment of script norms, distance measures, and Markov models developed from computer aided testing (CAT) data; and (3) performance ranking of subject data. It is demonstrated that interactive computer aided testing either by touch CRT's or personal computers is a useful research and training device for measuring pilot information management in diagnosing system failures in simulated flight situations. Performance is dictated by knowledge of aircraft sybsystems, initial pilot structuring of the failure symptoms and efficient testing of plausible causal hypotheses
Nuclear radiation analysis
A study program of radiation shielding against the deleterious effects of nuclear radiation on man and equipment is reported. The methods used to analyze the radiation environment from bremsstrahlung photons are discussed along with the methods employed by transport code users. The theory and numerical methods used to solve transport of neutrons and gammas are described, and the neutron and cosmic fluxes that would be present on the gamma-ray telescope were analyzed
How the minuscule can contribute to the big picture: the neutron electric dipole moment project at TRIUMF
A permanent electric dipole moment (EDM) of a fundamental particle violates
both parity (P) and time (T) reversal symmetry and combined charge and parity
(CP) reversal symmetry if the combined reversal of charge, parity \textit{and}
time (CPT) is preserved. It is a very promising place to search for physics
beyond the Standard Model. Ultracold neutrons (UCN) are the ideal tool to study
the neutron electric dipole moment since they can be observed for hundreds of
seconds. This article summarizes the current searches for the neutron EDM using
UCN and introduces the project to measure the neutron electric dipole moment at
TRIUMF using its unique accelerator driven spallation neutron and liquid helium
UCN source. The aim is to reach a sensitivity for the neutron EDM of around
cm.Comment: 12 pages, 6 figures, MENU 2016 Conference, Kyoto, Japa
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