Search NASA⌕ Search

SEARCH · Search NASA

Results for “One”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

One way Doppler tracking for on-orbit navigation

The integration of Doppler frequencies extracted from S-band communication and tracking signals received onboard an orbiting spacecraft provides a means of navigating on-orbit. This paper describes the one way Doppler tracking concept and two mechanizations which are being investigated by the Johnson Space Center to determine a suitable one way Doppler extraction technique for the Space Shuttle Orbiter and other advanced space systems. The designs of two breadboard models are outlined and measurement errors are discussed.

Lamoreux, J. C.↗
NASA NTRS1975

Robustly optimal rate one-half binary convolutional codes

Three optimality criteria for convolutional codes are considered in this correspondence: namely, free distance, minimum distance, and distance profile. Here we report the results of computer searches for rate one-half binary convolutional codes that are 'robustly optimal' in the sense of being optimal for one criterion and optimal or near-optimal for the other two criteria. Comparisons with previously known codes are made. The results of a computer simulation are reported to show the importance of the distance profile to computational performance with sequential decoding.

Johannesson, R.↗
NASA NTRS1975

The Noisiness of Low-Frequency One-Third Octave Bands of Noise

This study examined the relative noisiness of low frequency one-third octave bands of noise bounded by the bands centered at 25 Hz and 200 Hz, with intensities ranging from 50 db sound pressure level (SPL) to 95 db SPL. The thirty-two subjects used a method-of-adjustment technique, producing comparison-band intensities as noisy as standard bands centered at 100 Hz and 200 Hz with intensities of 60 db SPL and 72 db SPL. Four contours of equal noisiness were developed for one-third octave bands, extending down to 25 Hz and ranging in intensity from approximately 58 db SPL to 86 db SPL. These curves were compared with the contours of equal noisiness of Kryter and Pearsons. In the region of overlap (between 50 Hz and 200 Hz) the agreement was good.

Lawton, B. W.↗
NASA NTRS1975

The role of multiple scattering in one-dimensional radiative transfer

The usual methods of solving the radiative transfer equation yield answers which embrace all orders of scattering and thus shed little light on the underlying physical process. The present analysis examines the contributions of the various orders of scattering to the one dimensional transfer of radiation. In the one dimensional case an exact analytical solution exists and the problem reduces to that of expanding these exact solutions in powers of the albedo for single scattering. Formulas are given which permit the calculation of any order of scattering in an atmosphere of arbitrary optical thickness, particle albedo, and asymmetry parameter. The results should aid in identifying those physical situations where only the lowest orders of scattering play a significant role and where appropriate approximate methods might provide results of acceptable accuracy.

Adamson, D.↗
NASA NTRS1975

Chemically Reacting One-Dimensional Gas-Particle Flows

The governing equations for the one-dimensional flow of a gas-particle system are discussed. Gas-particle effects are coupled via the system momentum and energy equations with the gas assumed to be chemically frozen or in chemical equilibrium. A computer code for calculating the one-dimensional flow of a gas-particle system is discussed and a user's input guide presented. The computer code provides for the expansion of the gas-particle system from a specified starting velocity and nozzle inlet geometry. Though general in nature, the final output of the code is a startline for initiating the solution of a supersonic gas-particle system in rocket nozzles. The startline includes gasdynamic data defining gaseous startline points from the nozzle centerline to the nozzle wall and particle properties at points along the gaseous startline.

Tevepaugh, J. A.↗
NASA NTRS1976

Analysis of ECLSS performance during reentry after loss of one ammonia tank

An analysis was performed to determine whether, in case of a loss of one of the ammonia tanks, the Ammonia Boiler System can provide adequate heat rejection for the orbiter ECLSS during reentry. Results indicate that temperatures can be maintained as long as NH3 is available, but that one tank does not contain sufficient NH3 to complete all missions. A recommendation is made to investigate incorporation of onboard NH3 quantity calculations, and/or addition of a third NH3 tank.

Steines, G. J.↗
NASA NTRS1976

A comparison of one-dimensional theoretical models of stratospheric minor constituents

The density profiles of stratospheric minor constituents are compiled from several one-dimensional theoretical models that have appeared in the literature. The models are compared with each other and also with observations if data are available. The similarity and disparity of the models are clarified and discussed. If a large difference exists among the models, attempts are made to interpret it as much as possible in terms of the physical and chemical data employed in each model. The inadequacy of one-dimensional models in calculating the realistic ozone density distributions and the problems related to it are briefly discussed.

Shimazaki, T.↗
NASA NTRS1976

Encounters of spherical galaxies. I - Galaxy models with one stellar population. II - Galaxy models with two stellar populations

Close encounters between two spherical galaxies of equal size and consisting of only one stellar population are calculated using models of elliptical galaxies constructed according to King's (1966) method. The mass loss and the change in internal energy are computed under the assumption that the stars do not change their velocity or density distributions during the encounters. The results for a specific case are compared with the calculations of Gallagher and Ostriker (1972), who employed the observed brightness distribution and the derived density distribution of the E1 galaxy NGC 3379. For models with one stellar population, the results suggest that the radius of a galactic halo would have to be at least 200 kpc for appreciable mass loss to occur over the history of a galaxy in a rich cluster. The calculations are then extended to include a halo population characterized by a high central velocity dispersion. In this case, it is found that the halo population of sufficiently large galaxies can be dispersed without appreciably affecting the main population. It is suggested that the missing mass of many clusters of galaxies may be located in an intergalactic sea of faint stars making up an envelope for the centrally located gE galaxies.

Biermann, P.↗
NASA NTRS1976

Optimization of continuous one-dimensional structures under steady harmonic excitation

The paper examines some questions relating to the optimal design of continuous one-dimensional structures driven by harmonically oscillating loads. Optimal-control methods are applied to a cantilever bar driven sinusoidally by an axial force at its tip to illustrate the minimum-weight design of one-dimensional structures under dynamic excitation. Realistic constraints are imposed during the optimizations, including a maximum allowable stress amplitude at any point along the bar and a minimum cross-sectional area. It is shown that in the absence of damping, the design space may contain many disjoint feasible regions, and multiple optima can exist. Detailed solutions are obtained for continuous bars with an excitation frequency less than, and then greater than, the fundamental free-vibration frequency. It is found that above a certain excitation frequency, two or more arcs with different constraints characterize the optimal designs. It is concluded that when more than two different constrained arcs characterize the optimal solution, the continuum approach may be impractical, and finite-element approximations may offer the only alternative.

Johnson, E. H.↗
NASA NTRS1977

Phase substitution of spare converter for a failed one of parallel phase staggered converters

Failure detection and substitution of a spare module is provided in a system having a plurality of phase staggered modules connected in parallel to deliver regulated voltage from an unregulated source. Phase control signals applied to the active converter modules are applied to the spare module through NOR gates associated with and disabled by the power output of respective modules such that failure of any one enables its phase control signal to be applied to the spare module, thus controlling the spare module to operate in the phase position of the failed module. A NAND gate detects when any one active module fails and enables a gate in the spare module, thus activating the spare module.

Mclyman, W. T.↗
NASA NTRS1977

Effects of one-sided heat input and removal on axially grooved heat pipe performance

The performance of an axially grooved heat pipe with one-sided heat input and removal was investigated analytically. Under zero-g condition the maximum heat transport of the pipe may decrease as much as 30% depending on the liquid slug behavior in the condenser section. In one-g environment the performance depends mainly on the fluid charge. The maximum heat transport, if over-charged, is almost equal to the value for uniform heating and cooling due to puddling effect. However, for some heater-cooler combinations the temperature drop across the heat pipe becomes very large. Computed results for tilted heat pipes compare favorably with available experimental data.

Kamotani, Y.↗
NASA NTRS1977

Effect of flow on quasi-one-dimensional acoustic wave propagation in a variable area duct of finite length

The general equation for the velocity potential of quasi-one-dimensional acoustic wave motion in a variable area, finite duct with one-dimensional flow is derived by using a perturbation technique. The nonlinear second-order partial differential equation is linearized and then solved, by either a power series expansion method or the Runge-Kutta fourth-order method, for harmonic time dependence. The boundary condition taken at the duct mouth is that of matching the impedance of the duct sound field to that of the radiation field at the duct opening. Three axial Mach number variations along the duct axis are considered and the results obtained are compared with those for the case of constant Mach number, to determine the influence of the axial velocity gradient on sound propagation. The effect of flow on the radiation impedance is also considered.

Lumsdaine, E.↗
NASA NTRS1978

Monte Carlo simulation of the classical two-dimensional one component plasma

Monte Carlo simulation, lattice dynamics in the harmonic approximation, and solution of the hypernetted chain equation were used to study the classical two-dimensional one component plasma. The system consists of a single species of charged particles immersed in a uniform neutralizing background. The particles interact via a l/r potential, where r is the two dimensional separation. Equations of state were calculated for both the liquid and solid phases. Results of calculation of the thermodynamic functions and one and two particle correlation functions are presented.

Gann, R. C.↗
NASA NTRS1977

One-way Doppler extractor

This paper presents a feasibility analysis, tradeoffs, and implementation for a one-way Doppler extractor system. A Doppler error analysis is discussed which shows that quantization error is a primary source of Doppler measurement error. Several competing extraction techniques are compared, and a 'Vernier' technique is presented which obtains high Doppler resolution with low-speed logic. Parameter tradeoffs and sensitivities for this Vernier technique are discussed, leading to a hardware design configuration. Also presented is a performance evaluation of the resulting breadboard model that verifies the theoretical performance predictions. The breadboard model contains the circuitry to interface with an S-band transponder, to extract the Doppler and time-interval counts, to compute navigational parameters by means of a microprocessor, and to display the results. Performance tests have verified that the breadboard is capable of extracting Doppler, on an S-band signal, to an accuracy of better than 0.02 hertz for a one-second averaging period. This corresponds to a range rate error of no more than 3 millimeters per second.

Nossen, E. J.↗
NASA NTRS1978

One-dimensional inhomogeneous Vlasov equilibria

Bernstein, Greene, and Kruskal (1957) showed how, given the electrostatic potential as a function of position, the entire distribution function for ions, and the distribution function for untrapped electrons in a one-dimensional two-species Vlasov plasma, one could determine the distribution function for the trapped electrons as the solution of an Abel integral equation. This result is generalized by replacing the statements about the distribution functions with the specification of the velocity-space distribution functions of both species at a single position in the plasma. Limiting cases are shown to correspond to the earlier treatment, and the applicability of the theory to experiment is discussed.

Crownfield, F. R., Jr.↗
NASA NTRS1978

Electron trapping and transport by supersonic solitons in one-dimensional systems

A one-dimensional chain of ions or molecules and electrons described by a Froehlich-type Hamiltonian with quartic phonon anharmonicities is investigated. It is shown that the anharmonic lattice supports supersonic solitons which under favorable circumstances may trap electrons and transport them along the lattice. For a lattice constant/soliton spatial extent quotient of the order of 0.1, rough estimates give electron trapping energies in the meV range. They imply a useful temperature range, up to tens of degrees K, for observing the new effect. The activation energy of a lattice soliton is proportional to the molecular mass and is therefore quite high (about 1 eV) for typical quasi-one-dimensional organic systems.

Zmuidzinas, J. S.↗
NASA NTRS1979

Monte Carlo simulation of the classical two-dimensional one-component plasma

A Monte Carlo simulation, lattice dynamics in the harmonic approximation, and solution of the hypernetted chain equation are used to study the classical two-dimensional one-component plasma. A fluid phase is found for a specified dimensionless quantity, and a solid phase for higher values of this quantity. It is reported that the solid phase shows directional long range order, noting that in the solid phase positional long range order is lost as the thermodynamic limit is approached. Finally, the results of calculations of the thermodynamic functions and one- and two-particle correlation functions are presented.

Gann, R. C.↗
NASA NTRS1980

Feasibility of recovering a one million-pound booster

The concept of reusing spacecraft and launch vehicles is currently exemplified by the Space Shuttle Orbiter and the two recoverable and reusable solid rocket boosters (SRBs) which are part of its launch system. It is shown that it is possible to recover launch systems weighing as much as one million pounds at reasonable impact velocities using a hybrid parachute-retrorocket recovery system. The new Kevlar materials, which have a much higher strength-to-weight ratio than nylon materials, make it possible to recover a one-million-pound booster for a reasonable weight penalty. The selected input parameters to the parachute weight equation result in an accurate estimation of the current Space Shuttle solid rocket booster parachute recovery system.

Toni, R. A.↗