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The properties of materials selected for use in oxygen systems are examined. Specifically, materials are selected according to trade-offs between chemical compatibility, ignition temperature, combustion characteristics, and physical properties. Quantitative energy sources and energy release rates capable of causing material combustion or explosion were also considered.
This paper describes the use of decision analysis to facilitate a group decision-making problem in the selection of trajectories for the two spacecraft of the Mariner Jupiter/Saturn 1977 Project. This NASA project includes the participation of some eighty scientists divided by specialization among eleven science teams. A set of thirty-two candidate trajectory pairs was developed by the Project in collaboration with the science teams. Each science team then ordinally ranked and assigned cardinal utility function values to the trajectory pairs. These data and statistics derived from collective choice rules were used by the scientists in selecting the preferred trajectory pair.
A systematic rationale for selecting a cost-effective guidance and navigation (G & N) autonomy level for the solar electric propulsion stage (SEPS) vehicle is developed. After a definition of autonomy levels, a mission analysis is performed for representative SEPS missions using realistic G & N sensor hardware. Cost data for fabricating, integrating and refurbishing onboard avionics hardware and the ground costs corresponding to each autonomy level are generated. Results are presented that indicate performance of various G & N sensor hardware sets and the dominating factors which influence G & N autonomy level selection.
White rats selected preferred artificial gravity levels by locomotion in centrifuges consisting of two runways mounted in the nose of sounding rockets. Roll rate of the Aerobee 150A rocket was designed to produce an angular velocity of 45 rpm during 5 min of free-fall, providing a gravity range from 0.3 to 1.5 G depending on a subject's runway position. One animal was released at the high and one at the low gravity position in each flight. Animal positions were continuously recorded. Locomotion patterns during these flights were similar. All four animals explored the entire available G-range. One rat settled at 0.4 G after 2 min; the others crossed the 1-G location in progressively narrower excursions and were near earth gravity at the end of the test period. Tentatively, the data suggest that normal earth-reared rats select earth gravity when available magnitudes include values above and below 1 G. Modification of gravity preference by prolonged exposure to higher or lower levels remains a possibility.
The finite-element method for computing the extensional stress-intensity factor for cracks approaching selected singularities of varied geometry is described. Stress-intensity factors are generated using both displacement and J-integral techniques, and numerical results are compared to those obtained experimentally in a photoelastic investigation. The selected singularities considered are a colinear crack, a circular penetration, and a notched circular penetration. Results indicate that singularities greatly influence the crack-tip stress-intensity factor as the crack approaches the singularity. In addition, the degree of influence can be regulated by varying the overall geometry of the singularity. Local changes in singularity geometry have little effect on the stress-intensity factor for the cases investigated.
The selection, test, and evaluation of organic coating materials for contamination control in hybrid circuits is reported. The coatings were evaluated to determine their suitability for use as a conformal coating over the hybrid microcircuit (including chips and wire bonds) inside a hermetically sealed package. Evaluations included ease of coating application and repair and effect on thin film and thick film resistors, beam leads, wire bonds, transistor chips, and capacitor chips. The coatings were also tested for such properties as insulation resistance, voltage breakdown strength, and capability of immobilizing loose particles inside the packages. The selected coatings were found to be electrically, mechanically, and chemically compatible with all components and materials normally used in hybrid microcircuits.
Sideline noise and takeoff field length were varied for two types of Mach 2.32 cruise airplane to determine their effect on engine cycle selection. One of these airplanes was the NASA/Langley-LTV arrow wing while the other was a Boeing modified delta-plus-tail derived from the earlier 2707-300 concept. Advanced variable cycle engines were considered. A more conventional advanced low bypass turbofan engine was used as a baseline for comparison. Appropriate exhaust nozzle modifications were assumed, where needed, to allow all engines to receive either an inherent co-annular or annular jet noise suppression benefit. All the VCE's out-performed the baseline engine by substantial margins in a design range comparison, regardless of airplane choice or takeoff restrictions. The choice among the three VCE's considered, however, depends on the field length, noise level, and airplane selected.
The results from an experimental program to determine the reflection efficiency and scatter parameters of selected optical samples are presented. The measurements were made using 8.34A X-rays at various angles of incidence. Selected samples were contaminated after being measured and then remeasured to determine the effects of contamination. The instrumentation involved in taking the data, including the X-ray reflectometer and data processing equipment, is discussed in detail. The condition of the optical surfaces, the total reflection measurements, the scatter measurements, and the analysis are discussed.
Computer-aided corridor selection techniques, utilizing digitized data bases of socio-economic, census, and cadastral data, and developed for highway corridor routing are considered. Land resource data generated from various remote sensing data sources were successfully merged with the ancillary data files of a corridor selection model and prototype highway corridors were designed using the combined data set. Remote sensing derived information considered useful for highway corridor location, special considerations in geometric correction of remote sensing data to facilitate merging it with ancillary data files, and special interface requirements are briefly discussed.
Methods were studied of preparing anion-exchange membranes that would have low resistance, high selectivity, and physical and chemical stability when used in acidic media in a redox energy storage system. Of the twelve systems selected for study, only the system that was based on crosslinked poly-4-vinylpyridinium chloride produced physically strong membranes when equilibrated in l M HCl. The resistivity of the best membrane was 12 ohm-cm, and the transference number for chloride ions was 0.81.
The development of the conceptual design of high (1000 kW, 18 mph mean wind speed site) and low (100 kW, 12 mph site) power wind generator systems to be integrated into a standard electric utility is discussed. Analyses leading to the selection of the rotor and tower design are outlined. The 1000 kW system selected for further development utilizes an all composite rotor blade design and a steel shell tower. The projected energy cost is 3.5 cents/kW hr. Results of optimization of the rated power, site wind speed, and rated wind speed parameters are summarized.
The increasing need to develop alternative energy sources has renewed interest in the use of wind energy for the generation of utility quality electricity. This paper discusses a program to evolve a preliminary design of a cost competitive large wind generator system. An examination of a number of technically feasible alternative wind energy configurations is reported, and the rationale used in selecting the preferred system concept is presented. In addition, preliminary results of an optimization study conducted on the preferred concept are summarized. These show that considerable latitude in the selection of the system design parameters is possible. This permits design decisions to be based on other important factors such as development risk and the suitability of common component designs for systems with different power ratings.
During the past several years the Viking project developed plans to use Viking orbiter instruments and earth-based radar to certify the suitability of the landing sites selected as the safest and most scientifically rewarding using Mariner 9 data. During June and July 1976, the earth-based radar and orbital spacecraft observations of some of the prime and backup sites were completed. The results of these combined observations indicated that the Viking 1 prime landing area in the Chryse region of Mars is geologically varied and possibly more hazardous than expected, and was not certifiable as a site for the Viking 1 landing. Consequently, the site certification effort had to be drastically modified and lengthened to search for a site that might be safe enough to attempt to land. The selected site considered at 47.5 deg W, 22.4 deg N represented a compromise between desirable characteristics observed with visual images and those inferred from earth-based radar. It lies in the Chryse region about 900 kilometers northwest of the original site.
High speed data monitoring apparatus is described for displaying the bit pattern of a selected portion of a block of transmitted data comprising a shift register for receiving the transmitted data and for temporarily containing the consecutive data bits. A programmable sync detector for monitoring the contents of the shift register and for generating a sync signal when the shift register contains a predetermined sync code is included. A counter is described for counting the data bits input to the shift register after the sync signal is generated and for generating a count complete signal when a selected number of data bits have been input to the register. A data storage device is used for storing the contents of the shift register at the time the count complete signal is generated.
A model is described for planning and decision making in research project selection. Evaluations of each project's direct and indirect benefits, uncertainty in achieving these benefits, and schedule priority with resource budget and program balance constraints are considered. The combination of the interactive effect of project selection, resource allocation and scheduling considerations into one model permits tradeoff alternatives to be studied. Clients' value judgments are used in evaluating the benefits from each proposed project. The model is applied to the NASA Civil Helicopter Technology Program. Research project priorities for this program are established, strengths and weaknesses of the model are discussed, and areas of future development are recommended.
Key features of operational plans developed in a study of the Space Shuttle era life science payloads program are presented. The data describes the overall acquisition, staging, and integration of payload elements, as well as program implementation methods and mission support requirements. Five configurations were selected as representative payloads: (a) carry-on laboratories - medical emphasis experiments, (b) mini-laboratories - medical/biology experiments, (c) seven-day dedicated laboratories - medical/biology experiments, (d) 30-day dedicated laboratories - Regenerative Life Support Evaluation (RLSE) with selected life science experiments, and (e) Biomedical Experiments Scientific Satellite (BESS) - extended duration primate (Type I) and small vertebrate (Type II) missions. The recommended operational methods described in the paper are compared to the fundamental data which has been developed in the life science Spacelab Mission Simulation (SMS) test series. Areas assessed include crew training, experiment development and integration, testing, data-dissemination, organization interfaces, and principal investigator working relationships.
This publication contains a selection of ten papers by Professor Antonio Ferri, who died in 1976 after many years association with AGARD. These papers were selected by a committee composed of Professor P. Libby, Professor R. Monti, Professor R.G. Napolitano, Dr D.M. Rogers and Professor R.Vaglio, and are concerned with the advanced design of air vehicles. They are published to bring together in one place examples of Professor Ferri's most important contributions to aerospace research and development. A biography of Professor Ferri is included, together with a bibliography of his works, and tributes from his friends and colleagues.
Selection rules for nonlinear three-wave interactions are derived on the basis of the symmetry of the background medium and the waves themselves. The process described bypasses the formal derivation of the coupling coefficient itself. The primary concern is with the effect of the polarization of the waves on the selection rules. Although consideration is limited to three-wave interactions, the method is easily generalized to more waves. Results are derived for these examples: three waves with parallel propagation vectors in an unmagnetized medium, and three waves propagating parallel, and then perpendicular, to a static magnetic field.