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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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At least 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
NASA NTRS1965

Notes on System Theory, Volume VII

System theory - matrices, feedback control system, network synthesis, set theory, stability, shift registers, coding, theorem proving, polynomial roots, channels, and signal flow graphs

FEEDBACK CONTROL SYSTEM↗
NASA NTRS1963

Orbit prediction accuracy theory

Equations for estimating orbit prediction accuracy theory, with partial derivatives calculated from two-body elliptical orbit theory

ORBIT EQUATION↗
NASA NTRS1997

The Equivalence of Precession Phenomena in Metric Theories of Gravity

The requirement of general covariance imparts to metric theories of gravity, such as general relavity, important structural features. A precise mathematical form results, ensuring that computation of observable physical effects in the theory gives the same answers independently of the chosen system of coordinates.

metric theories gravitation relativity↗
NASA NTRS2017

Applying Graph Theory to Problems in Air Traffic Management

Graph theory is used to investigate three different problems arising in air traffic management. First, using a polynomial reduction from a graph partitioning problem, it is shown that both the airspace sectorization problem and its incremental counterpart, the sector combination problem are NP-hard, in general, under several simple workload models. Second, using a polynomial time reduction from maximum independent set in graphs, it is shown that for any fixed e, the problem of finding a solution to the minimum delay scheduling problem in traffic flow management that is guaranteed to be within n1-e of the optimal, where n is the number of aircraft in the problem instance, is NP-hard. Finally, a problem arising in precision arrival scheduling is formulated and solved using graph reachability. These results demonstrate that graph theory provides a powerful framework for modeling, reasoning about, and devising algorithmic solutions to diverse problems arising in air traffic management.

precision arrival scheduling↗
NASA NTRS2017

Applying Graph Theory to Problems in Air Traffic Management

Graph theory is used to investigate three different problems arising in air traffic management. First, using a polynomial reduction from a graph partitioning problem, it isshown that both the airspace sectorization problem and its incremental counterpart, the sector combination problem are NP-hard, in general, under several simple workload models. Second, using a polynomial time reduction from maximum independent set in graphs, it is shown that for any fixed e, the problem of finding a solution to the minimum delay scheduling problem in traffic flow management that is guaranteed to be within n1-e of the optimal, where n is the number of aircraft in the problem instance, is NP-hard. Finally, a problem arising in precision arrival scheduling is formulated and solved using graph reachability. These results demonstrate that graph theory provides a powerful framework for modeling, reasoning about, and devising algorithmic solutions to diverse problems arising in air traffic management.

computational complexity↗
NASA NTRS1963

Progress Report No. 3 on Studies in the Fields of Space Flight and Guidance Theory

This paper contains progress reports of NASA-sponsored studies in the areas of space flight theory and guidance theory. The studies are carried on by several universities and industrial companies. This progress report covers the period from June 15, 1962 to December 20, 1962. The technical supervisor of the contracts is W.E. Miner, Deputy Chief of the Future Projects Branch of Aeroballistics Division, George C. Marshall Space Flight Center.

SPACECRAFT GUIDANCE↗
NASA NTRS1965

Studies in the fields of space flight and guidance theory progress report no. 7, 23 jul. 1964 - 1 apr. 1965

The progress reports of NASA-sponsored studies in the areas of space flight and guidance theory are presented. The studies are carried on by several universities and industrial companies. This progress report covers the period from July 23, 1964 to April 1, 1965. The contracts are technically supervised by personnel of the Astrodynamics and Guidance Theory Division, Aero-Astrodynamics Laboratory, Marshall Space Flight Center.

NASA Program↗
NASA NTRS1967

Quasiparticle-ensemble theory for a normal Fermi liquid.

A quasiparticle ensemble ( Q ensemble) is constructed in which the number of quasiparticles with momentum k in the ensemble is conserved. The thermodynamic properties of this ensemble are related to those of the grand canonical ensemble. By comparison with explicit microscopic predictions of the theory, it is shown that this formulation is necessary if the third law of thermodynamics is to be satisfied, and that in this case, the Landau theory of a Fermi liquid follows as a natural consequence.

Quantum mechanics↗