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  • 1
    Publication Date: 2013-08-29
    Description: A kind of small hydrogen maser standard for timekeeping is being developed at Shanghai Observatory. The maser employs a cylindrical capacitively loaded cavity construction, resulting in significant size and weight reduction compared to a traditional hydrogen maser. The Q of the compact cavity is electronically enhanced by a suitable positive feedback into the cavity to enable sustained maser oscillation. The long-term stability of the maser is improved by a cavity frequency stabilization servo-system. The design and development of the maser, as well as photographs of the new maser system during the construction phase are described.
    Keywords: LASERS AND MASERS
    Type: NASA. Goddard Space Flight Center, Proceedings of the 23rd Annual Precise Time and Time Interval (PTTI) Applications and Planning Meeting; p 169-17
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  • 2
    Publication Date: 2019-06-28
    Description: An approach is proposed for computerized simulation of meshing of aligned and misaligned involute helical gears. Algorithms for TCA (Tooth Contact Analysis) computer programs were developed. Influence of misalignment on the shift of the bearing contact and transmission errors has been investigated. Numerical examples that illustrate the developed theory are provided.
    Keywords: Mechanical Engineering
    Type: NASA-TM-107451 , E-10732 , NAS 1.15:107451 , ARL-TR-1370
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  • 3
    Publication Date: 2019-06-28
    Description: Sweet potatoes were grown hydroponically using the nutrient film technique (NFT) in support of the Closed Ecological Life Support System (CELSS) program. Experiments in the greenhouse with the TI-155 sweet potato cultivar produced up to 1790 g/plant of fresh storage roots. Studies with both TI-155 and Georgia Jet cultivars resulted in an edible biomass index of approximately 60 percent, with edible biomass linear growth rates of 12.1 to 66.0 g m(exp -2)d(exp -1) in 0.05 to 0.13 sq meters in 105 to 130 days. Additional experimental results are given. All studies indicate good potential for sweet potatoes in CELSS.
    Keywords: MAN/SYSTEM TECHNOLOGY AND LIFE SUPPORT
    Type: NASA. Ames Research Center, Controlled Ecological Life Support Systems: CELSS '89 Workshop; p 119-126
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  • 4
    Publication Date: 2019-06-27
    Description: The effects are studied of an intraurban V/STOL commuter system on the economic, social, and physical environment of the San Francisco Bay Area. The Bay Area was chosen mainly for a case study; the real intent of the analysis is to develop methods by which the effects of such a system could be evaluated for any community. Aspects of the community life affected include: income and employment, benefits and costs, noise, air pollution, and road congestion.
    Keywords: GENERAL
    Type: NASA-CR-114492
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  • 5
    Publication Date: 2019-07-13
    Description: An approach for design and generation of low-noise helical gears with localized bearing contact is proposed. The approach is applied to double circular arc helical gears and modified involute helical gears. The reduction of noise and vibration is achieved by application of a predesigned parabolic function of transmission errors that is able to absorb a discontinuous linear function of transmission errors caused by misalignment. The localization of the bearing contact is achieved by the mismatch of pinion-gear tooth surfaces. Computerized simulation of meshing and contact of the designed gears demonstrated that the proposed approach will produce a pair of gears that has a parabolic transmission error function even when misalignment is present. Numerical examples for illustration of the developed approach are given.
    Keywords: MECHANICAL ENGINEERING
    Type: AD-A290187 , ARL-TR-573 , E-9056 , NAS 1.15:106696 , NASA-TM-106696 , Mechanisms Conference; Sep 11, 1994 - Sep 14, 1994; Minneapolis, MN; United States
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  • 6
    Publication Date: 2019-07-13
    Description: One of the goals of NASA's Advanced Life Support Program (ALS) for sustaining human life in space is to achieve a closed system in plant production and usage. That all inedible plant parts should be recycled or used in some way. A Tuskegee University team researching sweetpotato and peanut for ALS has developed paper products from dried sweet-potato stems and peanut shells. In this study, the sweet-potato stems and peanut shells were soaked separately in water for 48 hours. After 48 hours, researchers manually separated the pulp and the unusable parts. To form the paper, 160 g of pulp and water mixture was poured through a 15.1 cm (diameter) filtration funnel and the pulp was trapped on 15 cm (diameter) filter paper. The filter paper and pulp were dried in an air oven, and the filter paper was removed, An examination under a scanning electron microscope showed that the sweet-potato paper was composed of "fibers", whereas the peanut shell paper was composed of "blocks". Results of physical testing showed that the sweet-potato stem paper was stronger than the peanut shell paper. It is anticipated that there may be other uses of these products such as writing paper, bags and packaging material. Because of its biodegradability, it can be incorporated into the resource recycling system at the end of its use.
    Keywords: Nonmetallic Materials
    Type: NASA University Research Centers Technical Advances in Aeronautics, Space Sciences and Technology, Earth Systems Sciences, Global Hydrology, and Education; 2 and 3; 495-499; NONP-NASA-CD-1999011585
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  • 7
    Publication Date: 2019-07-13
    Description: The peanut is one of the crops chosen for use in NASA's Advanced Life Support Program (ALS). The peanut is a source of both oil and protein. After oil is extracted from the peanut, a protein rich flour remains. An edible peanut protein film is one use for this flour. Two types of film are developed for this study, one set of film contains 10% fat while the other set contains no fat. For film without fat the defatting of the peanut by the Soxhlet method is the first step in the manufacturing process of the film. Secondly, the protein is precipitated at its isoelectric point (pH 4.5) and centrifuged to separate the protein from the non-protein. After freeze-drying the protein it is milled in a ceramic ball mill to decrease particle size and sifted through a series of sieves to determine particle size distribution. Those particles retained on the 100 mesh sieves are utilized for film formation. Larger particles are re-ground and sifted. Five grams of protein is mixed with 50 mL of distilled water, 70 mL of 80% ethanol, 15 mL of 6N ammonium hydroxide and a plasticizer. This mixture is heated for 30 minutes until the temperature reaches 70 C. The mixture is then poured onto a level Teflon coated glass surface. After allowing the film to form overnight under a ventilation hood, it is manually removed from the plate. The processes and methods adopted have created flexible films of uniform thickness that are free of air bubbles. Thickness of films made from defatted peanut protein and partially defatted peanut protein were 0.10 Lm and 0.13 Lm respectively. Films with natural peanut fat are approximately three times as flexible and almost four times as strong as the films made without fat. Further research will be performed to evaluate its mechanical properties. This paper will greatly contribute to food preservation and waste management. Potential applications of this film are edible/biodegradable containers, wrapping for food preservation (against water, oxygen and oil), storage packets for seasonings or other ingredients and encapsulation for pharmaceutical use.
    Keywords: Man/System Technology and Life Support
    Type: NASA University Research Centers Technical Advances in Aeronautics, Space Sciences and Technology, Earth Systems Sciences, Global Hydrology, and Education; 2 and 3; 489-494; NONP-NASA-CD-1999011585
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  • 8
    Publication Date: 2019-07-13
    Description: A general approach developed for the computerized simulation of loaded gear drives is presented. In this paper the methodology used to localize the bearing contact, provide a parabolic function of transmission errors, and simulate meshing and contact of unloaded gear drives is developed. The approach developed is applied to spur and helical gears, spiral bevel gears, face-gear drives, and worm-gear drives with cylindrical worms.
    Keywords: Mechanical Engineering
    Type: AD-A310191 , NASA-TM-107250 , NAS 1.15:107250 , ARL-TR-1086 , Gears; Apr 22, 1996 - Apr 24, 1996; Dresden, Germany; Germany
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  • 9
    Publication Date: 2019-07-13
    Description: The present study reports recent measurements of the induced thermoluminescence (TL) properties of 69 type-3 ordinary chondrites, bringing to 125 the number of type-3 ordinary chondrites for which TL data are available. The samples include several of the particularly low petrographic type and many breccias, some of them gas-rich. The significance of the data with respect to the physical conditions affecting metamorphism is discussed. The TL data, olivine heterogeneity, carbon content, and inert-gas content were used to assign the samples to petrologic types. Twelve meteorites were identified as being type 3.0-3.2, and 10 of the breccias were found to contain material that may also be of this type. The temperature and width of the induced TL peak are also related to thermal history, with type 3.2-3.4 chondrites tending to have narrower peaks at lower glow curve temperatures than the type 3.6-3.9 chondrites. Type 3 H chondrites were found to be a higher petrographic type than the type 3 L and LL chondrites.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Science Conference; Mar 12, 1990 - Mar 16, 1990; Houston, TX; United States
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  • 10
    Publication Date: 2019-08-15
    Description: Many challenges are presented by biological degradation in a bioregenerative Controlled Ecological Life Support System (CELSS) as envisioned by the U.S. National Aeronautics and Space Administration (NASA). In the studies conducted with biodegradative microorganism indigenous to sweetpotato fields, it was determined that a particle size of 75 microns and incubation temperature of 30 degrees C were optimal for degradation. The composition of the inedible biomass and characterization of plant nutrient solution indicated the presence of potential energy sources to drive microbial transformations of plant waste. Selected indigenous soil isolates with ligno-cellulolytic or sulfate-reducing ability were utilized in biological studies and demonstrated diversity in ability to reduce sulfate in solution and to utilize alternative carbon sources: a lignin analog--4-hydroxy, 3-methoxy cinnamic acid, cellulose, arabinose, glucose, sucrose, mannitol, galactose, ascorbic acid.
    Keywords: Life Sciences (General)
    Type: Advances in space research : the official journal of the Committee on Space Research (COSPAR); 18; 2-Jan; 267-79
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