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  • MACHINE ELEMENTS AND PROCESSES  (51)
  • ASTROPHYSICS
  • Humans
  • Life and Medical Sciences
  • 2010-2014
  • 2000-2004
  • 1995-1999
  • 1970-1974  (67)
  • 1930-1934  (1)
  • 1925-1929
  • 1973  (67)
  • 1930  (1)
Collection
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Years
  • 2010-2014
  • 2000-2004
  • 1995-1999
  • 1970-1974  (67)
  • 1930-1934  (1)
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Year
  • 1
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    An economical method of analyzing transient motion of gas-lubricated rotor-bearing systems. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A method of economically evaluating the hydrodynamic forces generated in a gas-lubricated tilting-pad bearing is presented. The numerical method consists of solving the case of the infinite width bearing and then converting this solution to the case of the finite bearing by accounting for end leakage. The approximate method is compared to the finite-difference solution of Reynolds equation and yields acceptable accuracy while running about one-hundred times faster. A mathematical model of a gas-lubricated tilting-pad vertical rotor systems is developed. The model is capable of analyzing a two-bearing-rotor system in which the rotor center of mass is not at midspan by accounting for gyroscopic moments. The numerical results from the model are compared to actual test data as well as analytical results of other investigators.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: ASLE PREPRINT 73AM-2B-2 , Annual Meeting; Apr 30, 1973 - May 03, 1973; Chicago, IL
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
    Electronic Resource
    Electronic Resource
    Cell separation by velocity sedimentation of postnatal mouse cerebellum (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 81 (1973), S. 271-279 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Trypsinized cells of newborn mouse cerebellum have been separated by velocity sedimentation at unit gravity in shallow gradients of Ficoll. The two main technical difficulties were formation of gels around the dissociated cells and clumping of cells before and during the sedimentation procedure. These were solved by adding DNase to the dissociation medium and with holding serum, respectively. Proliferating cells of the external granular layer separated according to size differences in the cell generation cycle. Identification of Purkinje or other early-forming neurons was made by labeling them with 3H-thymidine on their birthdays. Many of the fractions contain viable cells capable of aggregating in culture.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040810215
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  • 3
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    Small, high pressure ratio compressor: Aerodynamic and mechanical design (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The Small, High-Pressure-Ratio Compressor Program was directed toward the analysis, design, and fabrication of a centrifugal compressor providing a 6:1 pressure ratio and an airflow rate of 2.0 pounds per second. The program consists of preliminary design, detailed areodynamic design, mechanical design, and mechanical acceptance tests. The preliminary design evaluate radial- and backward-curved blades, tandem bladed impellers, impeller-and diffuser-passage boundary-layer control, and vane, pipe, and multiple-stage diffusers. Based on this evaluation, a configuration was selected for detailed aerodynamic and mechanical design. Mechanical acceptance test was performed to demonstrate that mechanical design objectives of the research package were met.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-CR-120941 , APS-5404-R-VOL-1
    Format: application/pdf
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  • 4
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    Characterizations of four specimens processed as a part of the M553 sphere forming experiment performed during the Skylab 1 and 2 flight (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Four specimens identified as SL-1.3, SL-1.8, SL-1.9 and SL-2.5 were submitted for metallurgical characterization. These specimens had been processed in the M512 Facility as a part of the M553 Sphere Forming Experiment performed during the Skylab 1/2 flight. Three of these specimens, SL-1.3, SL-1.8, and SL-2.5 were designed to be melted completely by the electron beam and detach themselves from their support posts and resolidify while floating free in the near zero gravity and vacuum environment of space. Specimens SL-1.3 and SL-1.8 were completely melted, but it is believed they did not leave their posts before solidifying. Specimen SL-2.5 was only partially melted. Specimen SL-1.9 was to be completely melted and retained on a large sting which was accomplished as planned. The nominal composition of the four specimens was: (1) SL-1.3 - Ni 12% Sn; (2) SL-1.8 - Ni 30% Cu; (3) SL-1.9 - Pure Ni; and (4) SL-2.5 - Pure Ni. These four specimens have been examined according to the Phase B Characterization Plan. The results are discussed and compared with similar characterization analyses run on ground base specimens.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-CR-129040
    Format: application/pdf
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  • 5
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    Characterization of nickel-copper alloy specimens processed as a part of the M553 sphere forming experiment during the Skylab 1 and 2 flight (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Both processed nickel-copper alloy specimens apparently completely melted by the electron beam in the Skylab M512 materials processing facility and either floated free in space, but collided with some smooth flat surface before solidifying, or remained attached to its support post during solidification. Both specimens had a smooth flat area on the surface due to this adherence during solidification. The nominal composition of the alloy before processing in space was 70 percent Ni and 30 percent Cu. Tests show that a considerable amount of copper was lost during processing by evaporation. It was further found that less copper was present in the cap areas, particularly at the surface, than was in the remainder of the specimens. The microchemistry of the dendrites and interdendritic regions, however, is in agreement with the phase diagram for this alloy. The measured densities of these specimens were less than the theoretical density of the alloy due to the amount of porosity present, however, no large voids were found by radiographic techniques.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-CR-129039
    Format: application/pdf
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  • 6
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    Turbopumps for cryogenic upper stage engines (1973)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Small, high-performance LO2 and LH2 turbopump assembly configurations were selected, detail designs were prepared and two of each unit were fabricated with each unit consisting of pump, turbine gas generator, and appropriate controls. Following fabrication, development testing was conducted on each type to demonstrate performance, durability, transient characteristics, and heat transfer under simulated altitude conditions. Following successful completion of development effort, the two LO2 turbopump units and one LH2 turbopump unit were acceptance tested as specified. Inspection of the units following development testing revealed no deleterious effects of testing. The test results of LO2 turbopump assembly testing correlated well with predicted performance while the LH2 turbopump test results, though generally consistent with predicted values, did show lower than anticipated developed head at the design point and in the high flow range of operation.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-CR-120193
    Format: application/pdf
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  • 7
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    The effects of plasticity in adhesive fracture (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: An energy-balance analysis is presented for adhesive failure in end loaded cantilever beams. The analysis includes the effects of input work, stored strain energy, dissipated plastic energy, and specific adhesive surface energy. Experimental results obtained with 6061-T6 aluminum are presented as evidence for the validity of the approach.-
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Format: text
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  • 8
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    Development of improved electroforming technique (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Techniques were studied to reinforce or strengthen electroformed nickel to allow a fuller utilization of electroforming as a reliable and low cost fabrication technique for regenerately cooled thrust chambers. Techniques for wire wrapping while electrodepositing were developed that can result in a structurally strong wall with less weight than a conventional electroformed wall. Also a technique of codepositing submicron sized THO2 particles with the nickel to form a dispersion strengthened structure was evaluated. The standard nickel cylinders exhibited an average hoop strength of 80,000 psi with a yield strength of 65,000 psi and a modulus of 25.6 x 10 to the 6th power psi. The as produced dispersion strengthened nickel showed a hoop strength of 97,000 psi with a yield strength of 67,000 psi. This is an increase of 17,000 psi or 21% over the standard nickel hoop strength. The wire wrapping cylinders showed an increased strength over the standard nickel test samples of 26,000 to 66,800 psi which is in the range of 26 to 104% increase in strength over the base standard nickel. These latter test results are indicative of a volume percent wire reinforcement from 15 to 31. The measured hoop strengths agree with calculated composite strengths based upon rule of mixtures.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: NASA-CR-134480 , GTC-297
    Format: application/pdf
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  • 9
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    Detection of weldment lack of fusion using opaque additives (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Problems in the production of aluminum weldments are caused by moisture absorbed by the aluminum oxide which forms on the surface before welding. Another problem is incomplete penetration of the weldment. The problems can be solved by coating the aluminum surfaces with an X-ray-opaque metal such as silver or copper. This will prevent the formation of moisture-absorbing aluminum oxide. Any protective coating remaining in an area of incomplete weld penetration can be seen in an inspection of the weldment conducted with the aid of an X-ray method. Details of copper deposition procedures are discussed along with a copper coating analysis and the testing of the weldments.
    Keywords: MACHINE ELEMENTS AND PROCESSES
    Type: Symposium on Nondestructive Evaluation; Apr 25, 1973 - Apr 27, 1973; San Antonio, TX
    Format: text
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of composition of air on the growth and mortality of the chick embryo (1930)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 517-525 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fertilized hen's eggs of known origin were incubated under predetermined, standardized, and uniform conditions of all physical factors except air, the composition of which in respect to the carbon dioxide and oxygen varied in each experiment. The growth and mortality of the embryo were studied daily, with, on an average, four observations.The experimental data show that the continuous exposure to about 0.4 per cent of carbon dioxide in the air of the incubator stimulated growth during the first part of embryonic life. A high content of carbon dioxide and at the same time a slightly reduced content of oxygen resulted in diminishing of the size and increasing of mortality of the embryo. The maximum combined proportions of these gases possible for growth of the embryo were about 22.0 and 16.3 per cent, respectively. A temporary exposure (twenty-four and forty-eight hours) to a large amount of carbon dioxide resulted in diminishing the size of the embryo without apparent deformities or increase of mortality.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1050500210
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