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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Notions of analytic vs numerical stability as applied to the numerical calculation of orbits

This paper deals with the implications of 'stability' as applied to the numerical calculation of orbits. The study was motivated by the recent appearance of several proposed transformations of the classical Newtonian equations of motion which 'analytically stabilize' Cowell's method. This report analyzes the basic properties of such stabilizing transformations and shows the removal of the period as a parameter is the key to these transformations and, that although such transformations do not yield global numerical error bounds, the error propagation properties are more favorable - linear vs quadratic growth.

Velez, C. E.↗
NASA NTRS1966

History of the lunar orbit.

Calculating past states of earth-moon system based on three time scales for dynamical change

EARTH-MOON SYSTEM↗
NASA NTRS1991

A rapid method of calculating the orbital radiation environment

This paper describes the process of integrating available environment models into a single package that calculates the radiation environment for any earth orbit quickly and accurately with the only input being initial orbit parameters, launch date and length of mission, and units of output. The radiation dose is calculated for particles penetrating varying aluminum shielding thicknesses and incident upon several materials inside. Included also are modifications that have been made to the codes that account for the decrease of the magnetic field with time, which allows the use of data taken in the past to accurately predict a future environment. The complete package has relatively short run times, 20 minutes per mission on a Micro VAX II, allowing multiple iterations for application to mission design and planning.

Gates, Michele M.↗
DOE OSTI2022

Composite Correlated Molecular Orbital Theory Calculations of Ring Strain for Use in Predicting Polymerization Reactions

Strained ring systems play an important role in synthesis and can be characterized by the ring strain energy (RSE). The RSE of 3, 4, 5, and 6 membered saturated and unsaturated ring systems containing N, O, P, and S heteroatoms and H, F, SiMe 3 , and SO 2 Me substituents were calculated at the G3(MP2) composite correlated molecular orbital theory level using up to 5 models to predict the RSE. Generally, the RSE decreased as ring size increased with a substantial decrease from 4 to 5 membered rings. Replacement of a ring CH 2 with P or S reduced the RSE, consistent with less angle strain. The RSE for unsaturated systems were generally greater than for saturated systems due to increased angle strain. No general trends were found with respect to substituent effects. In conclusion, the RSE values suggest that 3-pyrroline and 2-pyrroline and their derivatives may be able to support ring opening metathesis polymerization and warrant further study.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Isolation and Study of Ruthenium–Cobalt Oxo Cubanes Bearing a High-Valent, Terminal Ru V –Oxo with Significant Oxyl Radical Character

High-valent Ru V -oxo intermediates have long been proposed in catalytic oxidation chemistry, but investigations into their electronic and chemical properties have been limited due to their reactive nature and rarity. The incorporation of Ru into the [Co 3 O 4 ] subcluster via the single-step assembly reaction of Co II (OAc) 2 (H 2 O) 4 (OAc = acetate), perruthenate (RuO 4 - ), and pyridine (py) yielded an unprecedented Ru(O)Co 3 (μ 3 -O) 4 (OAc) 4 (py) 3 cubane featuring an isolable, yet reactive, RuV-oxo moiety. EPR, ENDOR, and DFT studies reveal a valence-localized [Ru V (S = 1/2)Co III 3(S = 0)O 4 ] configuration and non-negligible covalency in the cubane core. Significant oxyl radical character in the Ru V -oxo unit is experimentally demonstrated by radical coupling reactions between the oxo cubane and both 2,4,6-tri-tert-butylphenoxyl and trityl radicals. The oxo cubane oxidizes organic substrates and, notably, reacts with water to form an isolable μ-oxo bis-cubane complex [(py) 3 (OAc) 4 Co 3 (μ 3 -O) 4 Ru]-O-[RuCo 3 (μ 3 -O) 4 (OAc) 4 (py) 3 ]. Redox activity of the Ru V -oxo fragment is easily tuned by the electron-donating ability of the distal pyridyl ligand set at the Co sites demonstrating strong electronic communication throughout the entire cubane cluster. Natural bond orbital calculations reveal cooperative orbital interactions of the [Co 3 O 4 ] unit in supporting the Ru V -oxo moiety via a strong π-electron donation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Orbital-resolved calculations of two-center interferences in linear triatomic molecules

In this report we perform ab initio calculations of high-harmonic spectroscopy (HHS) of two-center interference phenomena in oriented carbon-dichalcogen molecules, using time-dependent density functional theory (TDDFT). We show that by resolving the harmonic response into contributions from individual Kohn-Sham orbitals, we can extract target-specific characteristics for both the spectral amplitude and phase. We also discuss that this extraction is predicated on a careful analysis and normalization of the harmonic spectrum. Finally, we present field-free scattering calculations that mimic the recollision step in high-order-harmonic generation and allow the calculation of recombination dipole matrix elements without explicitly calculating the scattering states of a molecule. We show that the orbital-resolved TDDFT HHS results and results based on our field-free scattering calculations are in very good agreement with each other.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1981

Orbit improvement of the satellites of the outer planets

Data reduced from 127 plates showing Jupiter's and Saturn's satellites in the interval 1972 to 1974 are available on computer cards in the form of (O-C) residuals. Initial orbit calculations and several later orbit improvements for Jupiter XIII (Leda) culminated in an extended ephemeris for Leda to the year 2000. The possible existence of several small satellites just outside Saturns rings was predicted. De Sitter's incomplete theory for the motion of the Galilean satellites was reviewed and an outline for a revised, complete theory was developed. Observations of nearly 100 relative positions of the Galilean satellite with a mean accuracy of about 100 km (0.03 arc sec) were used to improve Sampson's theory for these satellites. Results were published on (1) a long term upper limit to Jupiter's orbital eccentricity; (2) deviation of an accurate modern value of the ellipticity of Uranus from balloon-borne images and consequent evaluation of the planet's rotation rate; and (3) identification of features in Saturn's rings as produced by heretofore undetected tesseral harmonics of Saturn's gravitational field.

Aksnes, K.↗