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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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This paper presents a middle ground between these two extremes that uses plans, but also enables much larger control envelopes using a real-time planner that finds optimal n step plans to achieve a set of goals if one exists.
While universal plans tell a system how to reach a goal regardless of what state it is in, such plans are typically too large to represent. Hybrid systems execute plans where each action is implemented to robustly produce effects if the world does not stray outside the action's control envelopes.
The Last Interglacial period (LIG) is a period with increased summer insolation at high northern latitudes, which results in strong changes in the terrestrial and marine cryosphere. Understanding the mechanisms for this response via climate modelling and comparing the models' representation of climate reconstructions is one of the objectives set up by the Paleoclimate Modelling Intercomparison Project for its contribution to the sixth phase of the Coupled Model Intercomparison Project. Here we analyse the results from 16 climate models in terms of Arctic sea ice. The multi-model mean reduction in minimum sea ice area from the pre industrial period (PI) to the LIG reaches 50 % (multi-model mean LIG area is 3.20×10^6 sq.km, compared to 6.46×10^6 sq.km for the PI). On the other hand, there is little change for the maximum sea ice area (which is 15–16×10^6 sq.km for both the PI and the LIG. To evaluate the model results we synthesise LIG sea ice data from marine cores collected in the Arctic Ocean, Nordic Seas and northern North Atlantic. The reconstructions for the northern North Atlantic show year-round ice-free conditions, and most models yield results in agreement with these reconstructions. Model–data disagreement appear for the sites in the Nordic Seas close to Greenland and at the edge of the Arctic Ocean. The northernmost site with good chronology, for which a sea ice concentration larger than 75 % is reconstructed even in summer, discriminates those models which simulate too little sea ice. However, the remaining models appear to simulate too much sea ice over the two sites south of the northernmost one, for which the reconstructed sea ice cover is seasonal. Hence models either underestimate or overestimate sea ice cover for the LIG, and their bias does not appear to be related to their bias for the pre-industrial period. Drivers for the inter-model differences are different phasing of the up and down short-wave anomalies over the Arctic Ocean, which are associated with differences in model albedo; possible cloud property differences, in terms of optical depth; and LIG ocean circulation changes which occur for some, but not all, LIG simulations. Finally, we note that inter-comparisons between the LIG simulations and simulations for future climate with moderate (1 %/yr) CO2 increase show a relationship between LIG sea ice and sea ice simulated under CO2 increase around the years of doubling CO2. The LIG may therefore yield insight into likely 21st century Arctic sea ice changes using these LIG simulations.
Slush drag and braking problems - conference papers
This document contains reproductions of technical papers presented at the NACA Conference on Helicopters held at the Langley Aeronautical Laboratory May 12 and 13, 1954. The primary purpose of this conference was to convey to the military services, their contractors, and others concerned with the design of helicopters the results of NACA research on helicopters and to provide those attending an opportunity to discuss the results. The papers in this document are in the same form in which they were presented at the conference in order to facilitate their prompt distribution. The original presentation and this record are considered as complementary to, rather than as substitutes for, the Committee's more complete and formal reports . A list of the conferees is included.
Rocket performance for isentropic process of chemically frozen hydrogen through converging- diverging nozzle
Space radiation - van allen belt, galactic cosmic radiation, solar wind & flares, and photon radiation with regard to apollo project
Space science - solar radiation, flame reaction kinetics, stratospheric planetary observatory, information systems, and space biology
Magnetic observatories for use during international quiet sun year /iqsy/
Analysis of preflight equipment failures of Agena rocket
Design of experiments for solar probe for measuring solar wind, particles, fields, and other interplanetary data
Acoustic and vibration data from Atlas E and F series vehicle flights
Conference on turbojet engine and supersonic propulsion
Chemical and physical properties of ortho and para hydrogen or mixtures of ortho and para hydrogen
Vibration, acoustic, and shock data tabulated for Titan II ICBM
Conference on aerodynamics of high speed aircraft
Proton and alpha particle range and stopping power data for space shielding materials
Turbojet engine characteristics, control systems, thrust augmentation, and inlet design studies for supersonic flight propulsion