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  • AERODYNAMICS  (448)
  • Cell & Developmental Biology  (205)
  • STRUCTURAL MECHANICS  (182)
  • GENERAL
  • 1975-1979  (795)
  • 1955-1959  (71)
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  • 1
    Publication Date: 2016-06-07
    Description: Results from recent investigations in the Langley V/STOL tunnel of an externally blown flap and an upper surface blown flap configuration in ground proximity are presented. Comparisons of longitudinal aerodynamic characteristics indicate that in ground proximity, drag is reduced for both configurations, but changes in lift are configuration dependent. Steady state analyses of the landing approach indicate an increase in flight path angle for both configurations in ground proximity because of the drag reduction. Dynamic analyses with a fixed-base simulator indicate that the resultant flight path during landing approach is dependent on the initial flight path angle and the control technique used.
    Keywords: AERODYNAMICS
    Type: Powered-Lift Aerodyn. and Acoustics; p 145-158
    Format: application/pdf
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  • 2
    Publication Date: 2019-07-13
    Description: An investigation of the transonic flow over a circular arc airfoil was conducted to obtain basic information for turbulence modeling of shock-induced separated flows and to verify numerical computer codes which are being developed to simulate such flows. The investigation included the employment of a laser velocimeter to obtain data concerning the mean velocity, the shear stress, and the turbulent kinetic energy profiles in the flowfield downstream of the airfoil midchord where the flow features are more complex. Depending on the free-stream Mach number, the flowfield developed was either steady with shock-wave-induced separation extending from the foot of the shock wave to beyond the trailing edge or unsteady with a periodic motion also undergoing shock-induced separation. The experimental data were compared with the results of numerical simulations in which a computer code was employed that solved the time-dependent Reynolds' averaged compressible Navier-Stokes equations.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 78-160 , Aerospace Sciences Meeting; Jan 16, 1978 - Jan 18, 1978; Huntsville, AL
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  • 3
    Publication Date: 2019-07-13
    Description: The analysis makes use of a singular perturbation method, the multiple time scaling. Concepts of stable and unstable limit cycles are introduced. The solution is obtained in the form of an asymptotic expansion. Numerical results are presented for the nonlinear flutter of panels and airfoils in supersonic flow. The approach used is an extension of a method for analyzing nonlinear panel flutter reported by Morino (1969).
    Keywords: STRUCTURAL MECHANICS
    Type: AIAA PAPER 75-102 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 20, 1975 - Jan 22, 1975; Pasadena, CA
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  • 4
    Publication Date: 2019-07-13
    Description: A combined experimental and computational research program for testing and guiding turbulence modeling within regions of separation induced by shock waves incident on turbulent boundary layers is described. Specifically, studies are made of the separated flow over the rear portion of an 18%-thick circular-arc airfoil at zero angle of attack in high Reynolds number supercritical flow. The measurements include distributions of surface static pressure and local skin friction. The instruments employed include high-frequency response pressure cells and a large array of surface hot-wire skin-friction gages. Computations at the experimental flow conditions are made using time-dependent solutions of ensemble-averaged Navier-Stokes equations, plus additional equations for the turbulence modeling.
    Keywords: AERODYNAMICS
    Type: ICAS PAPER 76-15 , Congress; Oct 03, 1976 - Oct 08, 1976; Ottawa; Canada
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  • 5
    Publication Date: 2019-06-27
    Description: The results of a program to design and fabricate an unshielded actively cooled structural panel for a hypersonic aircraft are presented. The design is an all-aluminum honeycomb sandwich with embedded cooling passages soldered to the inside of the outer moldline skin. The overall finding is that an actively cooled structure appears feasible for application on a hypersonic aircraft, but the fabrication process is complex and some material and manufacturing technology developments are required. Results from the program are summarized and supporting details are presented.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-2959
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  • 6
    Publication Date: 2019-07-13
    Keywords: AERODYNAMICS
    Type: SAE PAPER 750703 , West Coast Meeting; Aug 11, 1975 - Aug 14, 1975; Seattle, WA
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  • 7
    Publication Date: 2019-07-13
    Description: A detailed examination of the turbulent field in an unsteady transonic flow undergoing shock-induced separation is conducted. Ensemble-averaged mean and fluctuating velocities, obtained from conditionally sampled laser velocimeter data, are described and analyzed to assess the applicability of modeling concepts usually employed in steady-flow problems. Some comparisons with computations employing the Reynolds averaged Navier-Stokes equations with a mixing length turbulence model are then presented to illustrate the status of current predictive capabilities. The results appear to imply that turbulence models developed for steady flows apply and that the model need not reflect all the fine details of the turbulent structure but rather account in an approximate way for the production and destruction of the turbulence.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-0071 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 86 (1975), S. 177-189 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Various types of cells from the testes of mice and hamsters were separated according to differences in sedimentation velocity by centrifugal elutriation, a counterflow centrifugation technique. Approximately 3 × 108 cells, prepared from six mouse testes or from one hamster testis, were separated into 11 fractions in less than two hours as compared to the 4-5 hours required for sedimentation at unit gravity (“Staput”). Fractions enriched in elongated spermatids and spermatozoa (100%), stages 1-8 spermatids (69%) and pachytene spermatocytes (58%) were obtained from mouse testis dispersions. Similarly enriched fractions were obtained from hamster cells. A single fraction enriched in stages 1-8 spermatids (mouse) was prepared in less than 30 minutes. As many as 2 × 109 cells were separated in a single procedure. Spermatogenic cells exhibited no evidence of structural damage with trypan blue and phase microscopy, and recovery was essentially 100%. Centrifugal elutriation had no effect on sperm motility or on the plating efficiency of CHO cells.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 95 (1978), S. 275-285 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The relationship between plasminogen activator levels and the expression of the transformed phenotype was studied in a 5-bromodeoxyuridine (BrdUrd) dependent mutant of Syrian hamster melanoma cells. In terms of cell morphology and cellular interactions, the BrdUrd dependent cells resemble transformed cells when grown in the presence of BrdUrd but resemble untransformed cells when grown in the absence of BrdUrd. It was found that the BrdUrd dependent cells release significant levels of plasminogen activator only when cultured in the absence of BrdUrd. In the presence of BrdUrd, the release of plasminogen activator by the dependent cells is suppressed, and the decreased level of plasminogen activator released in the presence of BrdUrd seems to be due to decreased production of active enzyme. Growth tests revealed that the BrdUrd dependent cells, when attached to a substrate, required BrdUrd in order to attain high densities. Furthermore, the cells are able to grow well in soft agar only in the presence of BrdUrd. These results suggest that the production and release of high levels of plasminogen activator are not related (either as cause or effect) to the expression of the transformed phenotype in the BrdUrd dependent cellsThe effect of dog serum (as a plasminogen source) on the BrdUrd dependent cells also was tested. It was found that cells cultured in medium containing dog serum exhibit a morphological alteration, but only in the absence of BrdUrd. The morphological response of the cells to dog serum resembles that previously observed with virus-transformed cells. In the BrdUrd dependent cells, the morphological response to dog serum appears correlated with the release of plasminogen activator but separated from other transformed characteristics.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Alveolar macrophages harvested by bronchopulmonary lavage from rats exposed to tobacco smoke for 30 days (“smokers”) showed alterations in oxidative metabolism, lactate production and phagocytosis of inert starch particles when compared with control macrophages. Phagocytosis of viable Staphylococcus aureus was unaffected by tobacco smoke. Glucose oxidation measured by conversion of glucose-1-14C to 14CO2 was moderately affected while oxidation of glucose-6-14C to 14CO2 was not. Smokers routinely yielded fewer cells than controls, though these cells contained approximately 17% more protein than did controls. Opsonization of particles was not necessary for macrophages from either smoker or control animals to manifest a respiratory burst and increased superoxide and hydrogen peroxide release during phagocytosis. The glycolytic inhibitors, sodium fluoride and iodoacetamide, while effectively blocking glycolysis, did not inhibit phagocytosis by macrophages from either group. The results reported clearly distinguish alveolar macrophages from other phagocytic cells (peritoneal macrophages and polymorphonuclear leukocytes) and suggest a state of non-specific activation caused by exposure to tobacco smoke.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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