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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

TAC BRAWLER - An application of engagement simulation modeling to simulator visual system display requirements for air combat maneuvering

The TAC BRAWLER air combat simulation models both the acquisition and use of visual information by the pilot. It was used to provide the designers of manned simulators for air-to-air combat with information regarding the training implications of display system resolution, inherent target contrast, field of view, and transport delay. Various display designs were simulated, and the resulting quantitative and qualitative differences in engagements were considered indicators of possible mistraining. Display resolution was found to alter combats primarily through its effect on detection ranges; the 'pixel averaging' contrast management technique was shown to largely compensate for this problem. Transport delay significantly degrades pilot tracking ability, but the training impact of the effect is unclear.

Kerchner, R. M.↗
NASA NTRS1998

Production of neutrons from interactions of GCR-like particles

In order to help assess the risk to astronauts due to the long-term exposure to the natural radiation environment in space, an understanding of how the primary radiation field is changed when passing through shielding and tissue materials must be obtained. One important aspect of the change in the primary radiation field after passing through shielding materials is the production of secondary particles from the breakup of the primary. Neutrons are an important component of the secondary particle field due to their relatively high biological weighting factors, and due to their relative abundance, especially behind thick shielding scenarios. Because of the complexity of the problem, the estimation of the risk from exposure to the secondary neutron field must be handled using calculational techniques. However, those calculations will need an extensive set of neutron cross section and thicktarget neutron yield data in order to make an accurate assessment of the risk. In this paper we briefly survey the existing neutron-production data sets that are applicable to the space radiation transport problem, and we point out how neutron production from protons is different than neutron production from heavy ions. We also make comparisons of one the heavy-ion data sets with Boltzmann-Uehling-Uhlenbeck (BUU) calculations.

Non-NASA Center↗
NASA NTRS1976

The effect of adiabatic focusing upon charged-particle propagation in random magnetic fields

The charged particles considered are scattered by random fields while they propagate along the diverging lines of force of a spatially inhomogeneous guiding field. Their longitudinal transport is described in terms of the eigenfunctions of a Sturm-Liouville operator which incorporates the effect of adiabatic focusing along with that of scattering. The relaxation times and characteristic velocities which appear in this matrix formulation of the transport problem are graphed and tabulated. Explicit formulas which describe the particle-density profile that results from a localized impulsive injection are derived for two different regimes. In the first regime, where focusing is relatively weak, a diffusive mode of propagation is dominant, but coherent modes are also present, and they become prominent as the intensity of focusing increases. In the second regime, where focusing is strong and where diffusion does not occur, the propagation is purely coherent. The existence of this supercoherent mode of particle transport opens up many possibilities for the interpretation of astrophysical phenomena.

Earl, J. A.↗
NASA NTRS1966

Turbopause processes and effects.

Average rate of eddy mixing obtained from some eddy transport problems in thermosphere, noting molecular diffusion

ATMOSPHERIC DIFFUSION↗
NASA NTRS1967

Turbopause processes and effects.

Average rate of eddy mixing obtained from some eddy transport problems in thermosphere, noting molecular diffusion

ATMOSPHERIC DIFFUSION↗
NASA NTRS1971

Study of aircraft in intraurban transportation systems, San Francisco Bay area

The nine-county San Francisco Bay area is examined in two time periods (1975-1980 and 1985-1990) as a scenario for analyzing the characteristics of an intraurban, commuter-oriented aircraft transportation system. Aircraft have dominated the long-haul passenger market for some time, but efforts to penetrate the very-short-haul intraurban market have met with only token success. Yet, the characteristics of an aircraft transportation system-speed and flexibility-are very much needed to solve the transportation ills of our major urban areas. This study attempts to determine if the aircraft can contribute toward solving the transportation problems of major metropolitan areas and be economically viable in such an environment.

Source record↗
NASA NTRS1974

Urban transportation: Perspectives on mobility and choice

A study of urban transportation systems are presented characterized by intensive scrutiny of many ideas, philosophies, and academic perspectives. This report is intended to communicate some dimensions of the urban transportation problem to the general public.

Sincoff, M. Z.↗
NASA NTRS1974

Technology transfer-transportation

The application of aerospace technology to the solution of urban public transportation problems is considered. Data are given on highway and railway systems with particular attention given to safety devices, fuel economy, and measures for profiling railways and highways. The development of streamlined truck bodies, to reduce air drag, and efficient brake systems for light trucks and other vehicles was also dealt with.

Anyos, T.↗
NASA NTRS1977

Solar-power mountain concept

Solar collectors on mountainside collect thermal energy for mountaintop powerplant. Sloped arrangement reduces heat-transport problem of level ground-based collector field. Heated air rises without mechanical pumps and buoyancy force supplies pumping power without further cost. Precision tracking requirement of power towers eliminated by butted-together Winston-type concentrator troughs. Low-cost native rock is used for heat storage.

Clarke, V. C., Jr.↗
NASA NTRS1978

Radiative transfer calculated from a Markov chain formalism

The theory of Markov chains is used to formulate the radiative transport problem in a general way by modeling the successive interactions of a photon as a stochastic process. Under the minimal requirement that the stochastic process is a Markov chain, the determination of the diffuse reflection or transmission from a scattering atmosphere is equivalent to the solution of a system of linear equations. This treatment is mathematically equivalent to, and thus has many of the advantages of, Monte Carlo methods, but can be considerably more rapid than Monte Carlo algorithms for numerical calculations in particular applications. We have verified the speed and accuracy of this formalism for the standard problem of finding the intensity of scattered light from a homogeneous plane-parallel atmosphere with an arbitrary phase function for scattering. Accurate results over a wide range of parameters were obtained with computation times comparable to those of a standard 'doubling' routine. The generality of this formalism thus allows fast, direct solutions to problems that were previously soluble only by Monte Carlo methods. Some comparisons are made with respect to integral equation methods.

Esposito, L. W.↗
NASA NTRS1980

Temperature and composition measurements from the l.r.i.r. and l.i.m.s. experiments on Nimbus 6 and 7

The limb radiance inversion radiometer (LRIR) on Nimbus 6 was the first orbiting infrared limb scanner; it has four channels with which to determine temperature, O3, and H2O in the stratosphere and low mesosphere. The limb infrared monitor of the stratosphere (LIMS) is a similar six-channel instrument which was launched on Nimbus 7 in October 1978 in order to measure O3, H2O, NO2, and HNO3. The instrumentation and inversion techniques are briefly described, and the application of limb scanner data to the study of photochemical, dynamical, and transport problems is discussed.

Gille, J. C.↗
NASA NTRS1984

Predicting Moisture Absorption in Composite Materials

Heat transport programs adaptable for absorption analysis. Lightweight sandwich panel specimen used for comparison of water absorption measurements with program predictions. In program model, moisture -- like heat in heat-transport problem moves through variety of materials and structures along complex paths.

Haines, J. R.↗
NASA NTRS1985

Time-dependent radiation transport in a one-dimensional medium

An analytic solution of the time-dependent radiation transport problem in a one-dimensional, stationary and homogeneous medium of finite thickness is presented. The solution is found by the method of images, and is compared with an eigenfunction expansion. Previous conjectures about the structure of such an expansion are clarified. The Green's function of this problem is also expanded in scattering orders.

Nagel, W.↗
NASA NTRS1987

A benchmark for galactic cosmic ray transport codes

A nontrivial analytic benchmark solution for galactic cosmic ray transport is presented for use in transport code validation. Computational accuracy for a previously-developed cosmic ray transport code is established to within one percent by comparison with this exact benchmark. Hence, solution accuracy for the transport problem is mainly limited by inaccuracies in the input spectra, input interaction databases, and the use of a straight ahead/velocity-conserving approximation.

Wilson, John W.↗