Search NASA⌕ Search

SEARCH · Search NASA

Results for “PRIMARY”

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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Testing for hydrogen embrittlement: Primary and secondary influences

An overview is presented of the hydrogen embrittlement process, both internal as well as external, to make more clear the type of parameters which must be considered in the selection of a test method and test procedure, so that the resulting data may be meaningfully applied to real engineering structures. Three primary influences on the embrittlement process are considered: (1) the original location and form of the hydrogen, (2) the transport reactions involved in the transport of hydrogen from its origin to some point where it can interact with the metal to cause embrittlement, and (3) the embrittlement interaction itself. A few secondary influences on the embrittlement process are also discussed.

Nelson, H. G.↗
NASA NTRS1971

The energy spectrum of primary cosmic ray electrons from 2 GeV to 200 GeV.

Use of a balloon-borne counter telescope with a gas Cerenkov counter to measure the energy of primary cosmic ray electrons between 2 and 200 GeV. Electrons are identified by the characteristic electron-photon shower which they produce in a 15 radiation length deep stack of high-Z material interleaved with scintillation counters. Calibrations with monoenergetic electrons up to 14 GeV and monoenergetic protons up to 28 GeV from accelerators are used to develop criteria to statistically separate electrons from proton-induced events. The results from six balloon flights (total exposure time 63 hours) are combined to obtain the electron energy spectrum. Up to about 30 GeV, the spectrum measured in this experiment can be directly checked with calibrations and agrees well with results from other experiments. Above this energy, the flux reported in the present work is somewhat higher than the determinations reported by most other authors. An apparent flattening of the energy spectrum above 50 GeV is not regarded as significant. There is no evidence for a steepening of the spectrum at energies below 200 GeV.

Fanselow, J. L.↗
NASA NTRS1972

Search for antimatter in primary cosmic rays.

Data from two flights of a new superconducting magnetic spectrometer are reported. This instrument was capable of a direct matter-antimatter separation in the cosmic rays. Antimatter events would appear in the spectrometer as trajectories which curve in the opposite direction to common matter, because of their negative charge. A brief description of the equipment and of the characteristics of the instrument is presented, along with the data processing techniques used. A new upper limit on the amount of antimatter in primary cosmic rays has been established. The limits are considerably lower than those for any previous experiment.

Buffington, A.↗
NASA NTRS1972

A search for antihelium in primary cosmic radiation.

A search for anti-alpha-particles in the primary cosmic radiation has been carried out, and a new upper limit for these particles in the range 0.2-4.3 GeV per nucleon has been obtained. At the 95 per cent confidence level the upper limit is found to be 0.14 per cent of the alpha-particle flux. The instrument used for this purpose is a magnetic spectrometer employing spark chambers for determining particle trajectories and time-of-flight measurement for the rejection of upward-moving particles. Implications of these results for various models of the sources of cosmic radiation are discussed.

Evenson, P.↗
NASA NTRS1970

Discrete control of linear distributed systems with application to the deformable primary mirror of a large orbiting telescope

The results are presented of a detailed study of the discrete control of linear distributed systems with specific application to the design of a practical controller for a plant representative of a telescope primary mirror for an orbiting astronomical observatory. The problem of controlling the distributed plant is treated by employing modal techniques to represent variations in the optical figure. Distortion of the mirror surface, which arises primarily from thermal gradients, is countered by actuators working against a backing structure to apply a corrective force distribution to the controlled surface. Each displacement actuator is in series with a spring attached to the mirror by means of a pad intentionally introduced to restrict the excitation of high-order modes. Control is exerted over a finite number of the most significant modes.

Creedon, J. F.↗
NASA NTRS1972

A Study of Heavy Trans-Iron Primary Cosmic Rays (Z More than or Equal to 55) with a Fast Film Cerenkov Detector

The detection and measurement of the cosmic ray charge spectrum for nuclei heavier than iron (Fe, Z = 26) are discussed. These trans-iron nuclei are of great interest for several reasons. They promise to be one of the more sensitive clocks for use in determining the age of cosmic rays. The discovery of radioactive nuclides and their decay products in the primary flux, will allow an estimation of the elapsed time since these cosmic rays were synthesized. In addition, the relatively short interaction length of the very heavy trans-iron particles makes their relative abundance a source of information regarding the amount of interstellar matter that they had to traverse to reach the earth. A study of the trans-iron cosmic rays may provide clues as to the very processes of nucleosyntheses by which the bulk of the trans-iron nuclei in the universe are produced. This in turn may shed light on the mechanics of the supernova, which is postulated to be the major source of all cosmic rays. Finally, trans-iron cosmic ray experiments may demonstrate the existence of the recently postulated super-heavy nuclei.

Pinsky, L. S.↗
NASA NTRS1973

Effects of backlash and dead band on temperature control of the primary loop of a conceptual nuclear Brayton space powerplant

An analytical study was made of the stability of a closed-loop liquid-lithium temperature control of the primary loop of a conceptual nuclear Brayton space powerplant. The operating point was varied from 20 to 120 percent of design. A describing-function technique was used to evaluate the effects of temperature dead band and control coupling backlash. From the system investigation, it was predicted that a limit cycle will not exist with a temperature dead band, but a limit cycle will not exist when backlash is present. The results compare favorably with a digital computer simulation.

Petrick, E. J.↗
NASA NTRS1973

Effect of primary-zone water injection on pollutants from a combustor burning liquid ASTM A-1 and vaporized propane fuels

A combustor segment 0.457 meter (18 in.) long with a maximum cross section of 0.153 by 0.305 meter (6 by 12 in.) was operated at inlet-air temperatures of 590 and 700 K, inlet-air pressures of 4 and 10 atmospheres, and fuel-air ratios of 0.014 and 0.018 to determine the effect of primary-zone water injection on pollutants from burning either propane or ASTM A-1 fuel. At a simulated takeoff condition of 10 atmospheres and 700 K, multiple-orifice nozzles used to inject water at 1 percent of the airflow rate reduced nitrogen oxides 75 percent with propane and 65 percent with ASTM A-1 fuel. Although carbon monoxide and unburned hydrocarbons increased with water injection, they remained relatively low; and smoke numbers were well below the visibility limit.

Ingebo, R. D.↗
NASA NTRS1973

Tracking and data system support for the Mariner Mars 1971 mission. Volume 3: Orbit insertion through end of primary mission

The Tracking and Data System (TDS) Support for the Mariner Mars 1971 Mission final report contains the deep space tracking and data acquisition activities in support of orbital operations. During this period a major NASA objective was accomplished: completion of the 180th revolution and 90th day of data gathering with the spacecraft about the planet Mars. Included are presentations of the TDS flight support pass chronology data for each of the Deep Space Stations used, and performance evaluation for the Deep Space Network Telemetry, Tracking, Command, and Monitor Systems. With the loss of Mariner 8 at launch, Mariner 9 assumed the mission plan of Mariner 8, which included the TV mapping cycles and a 12-hr orbital period. The mission plan was modified as a result of a severe dust storm on the surface of Mars, which delayed the start of the TV mapping cycles. Thus, the end of primary mission date was extended to complete the TV mapping cycles.

Barnum, P. W.↗
NASA NTRS1973

Analysis of the dynamics of thin primary mirrors for large astronomical telescopes

The NASTRAN structural analysis program was used to investigate the dynamic properties of thin primary mirrors suitable for use in large orbiting astronomical telescopes. An analysis is included of the mode shapes and modal frequencies for several thin, homogeneous, isotropic mirrors. Typical cases include two different mirror diameters, two different diameter-to-thickness ratios, and both a mirror without and a mirror with a central hole that is 22 percent of the mirror diameter. The finite-element structural model is evaluated by comparing the NASTRAN generated results with theoretical values for a simply supported, flat, circular mirror. The same model is then used for evaluating the spherical mirrors. The mode shapes and frequencies of a 0.762-meter-diameter mirror with a 60-to-1 diameter-to-thickness ratio and a three-point rigid kinematic (not overconstrained) mount are calculated and plotted for comparison with results obtained previously from the SAMIS structural analysis program for this same mirror. A static analysis is also shown for comparison with experimentally obtained influence coefficients.

Ostroff, A. J.↗
NASA NTRS1973

Primary electron spectrometer, 18:63 UE: Electrostatic analyzer description and energy spectrum determination

The primary electron spectrometer used to detect auroral electrons on sounding rocket 18:63 UE is described. The spectrometer used exponentially decaying positive and negative voltages applied to spherical deflection plates for energy analysis. A method for determining the analyzer response which does not require the assumptions that the ratio of plate separation to mean radius, the entrance or the exit apertures are small is described. By comparison with experiment it is shown that the effect of neither entrance nor exit collimation can be ignored. The experimental and calculated values of the limiting orbits agree well. A non-iterative technique of unfolding the electron differential energy spectrum is described. This method does not require the usual assumption of a flat or histogram-type energy spectrum. The unfolded spectra using both this technique and one which assumes a flat spectrum are compared to actual input spectra. This technique is especially useful in analyzing peaked auroral electron energy spectra.

Pongratz, M. B.↗
NASA NTRS1973

Primary and secondary nuclei in high-energy cosmic rays

Charge and particle trajectory measurements during a balloon-borne experiment observing the composition of cosmic rays, are interpreted by plotting differential intensities of various nuclei of both primary and secondary origin above 3 GeV/nucleon. The large spectral difference between carbon plus oxygen and iron is confirmed in the difference between their secondary products. This large difference cannot be explained as being solely due to propagation effects and it is concluded that preferential acceleration of heavy nuclei due to a source effect is present.

Ormes, J. F.↗
NASA NTRS1972

Semicircular canals as a primary etiological factor in motion sickness.

Data are presented which support the view that the semicircular canals of humans can act as the essential factor for the production of motion sickness and the evocation of symptoms characteristic of this malady in the absence of 'motion.' Quantitative grading of acute symptoms demonstrated that motion sickness can be evoked by stimuli which are adequately provocative and unique for the canals. These results are compared with those of two provocative rotational tests that introduce Coriolis (cross-coupled angular acceleration) forces or generate a rotating linear acceleration vector. Wide interindividual differences but only slight intraindividual differences among the six provocative test conditions are revealed, indicating that individuals usually possess an overall susceptibility to motion which is relatively independent of its type. The fact that typical symptoms of motion sickness were also produced by bithermal irrigation of several subjects who represented a wide range of susceptibility adds to the evidence that semicircular canals can act as the primary etiological factor in this malady.

Miller, E. F., II↗
NASA NTRS1973

Ablation debris and primary micrometeoroids in the stratosphere.

Analysis of micrometer-sized stratospheric particulates suggests that the majority of extraterrestrial material in the atmosphere is the product of ablation of larger bodies. Ablation debris is of considerable interest because of the possibility that much of it may have originated from classes of easily fragmented meteoroids that are incapable of surviving atmospheric entry to become meteorites. Comparison is made between the elemental abundance patterns found in stratospheric particulates and that found in fusion crusts of primitive meteorite types. Also discussed are criteria for distinguishing ablation products from primary unablated micrometeoroids.

Brownlee, D. E.↗
NASA NTRS1974

Charge composition of high energy heavy primary cosmic ray nuclei

A detailed study of the charge composition of primary cosmic radiation for about 5000 charged nuclei from neon to iron with energies greater than 1.16 GeV/nucleon is presented. Values are obtained after corrections were made for detector dependences, atmospheric attenuation, and solar modulation. New values of 38.5, 32.4, 23.7, and 16.8 g/sq cm for the attenuation mean free paths in air for the same charge groups are presented.

Price, R. D.↗
NASA NTRS1972

Primary cosmic ray particles with z 35 (VVH particles)

Large areas of nuclear emulsions and plastic detectors were exposed to the primary cosmic radiation during high altitude balloon flights. From the analysis of 141 particle tracks recorded during a total exposure of 1.3 x 10 to the 7th power sq m ster.sec., a charge spectrum of the VVH particles has been derived.

Blanford, G. E., Jr.↗
NASA NTRS1974

Space shuttle/food system study. Volume 2, Appendix F: Flight food and primary packaging

The analysis and selection of food items and primary packaging, the development of menus, the nutritional analysis of diet, and the analyses of alternate food mixes and contingency foods is reported in terms of the overall food system design for space shuttle flight. Stowage weights and cubic volumes associated with each alternate mix were also evaluated.

Source record↗
NASA NTRS1974

Effect of primary-zone equivalence ratio and hydrogen addition on exhaust emission in a hydrocarbon-fueled combustor

The effects of reducing the primary-zone equivalence ratio on the exhaust emission levels of oxides of nitrogen, carbon monoxide, and unburned hydrocarbons in experimental hydrocarbon-fueled combustor segments at simulated supersonic cruise and idle conditions were investigated. In addition, the effects of the injection of hydrogen fuel (up to 4 percent of the total weight of fuel) on the stability of the hydrocarbon flame and exhaust emissions were studied and compared with results obtained without hydrogen addition.

Norgren, C. T.↗