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  • AERODYNAMICS  (546)
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  • 1
    Publication Date: 2011-08-19
    Description: A previous finite-element analysis of vertical Bridgman growth for dilute and nondilute alloys is extended to include the effect of a vertically-aligned magnetic field in the limit of zero magnetic Reynolds number. Calculations are presented for growth of a dilute gallium-germanium alloy in a vertically stabilized Bridgman-Stockbarger system and in a furnace with a uniform temperature gradient imposed along the ampoule. Steady cellular convection driven by radial temperature gradients causes good axial and radial mixing in both systems without a magnetic field. A weak magnetic field decreases the intensity of convection and the effectiveness of solute mixing. The radial nonuniformity is greatest for an intermediate field strength. Stronger fields suppress flow recirculation completely, and lead to uniform solute segregation across the crystal and to diffusion-controlled axial segregation.
    Keywords: MATERIALS PROCESSING
    Type: Journal of Crystal Growth (ISSN 0022-0248); 89; 2-3,; 339-356
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  • 2
    Publication Date: 2011-08-19
    Description: A fully time-dependent linear stability analysis of the morphological stability of a planar interface during directional solidification of a binary alloy at constant velocity in the presence of an electric field, is performed. The electromigration of solute and the differing electrical conductivities of solid and liquid for a model in which the temperature gradient is constant are taken into account. The present results are compared with the constitutional supercooling criterion, and it is shown there may be substantial differences. A modified constitutional supercooling criterion which is valid over a large range of conditions is derived. It is also found under certain conditions that the onset of instability may be time dependent.
    Keywords: MATERIALS PROCESSING
    Type: Journal of Crystal Growth (ISSN 0022-0248); 88; 1, Ap; 1-15
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  • 3
    Publication Date: 2011-08-19
    Description: A simple device is described for controlling vapor equilibrium in macromolecular crystallization as applied to the protein crystal growth technique commonly referred to as the 'hanging drop' method. Crystal growth experiments with hen egg white lysozyme have demonstrated control of the nucleation rate. Nucleation rate and final crystal size have been found to be highly dependent upon the rate at which critical supersaturation is approached. Slower approaches show a marked decrease in the nucleation rate and an increase in crystal size.
    Keywords: MATERIALS PROCESSING
    Type: Analytical Biochemistry (ISSN 0003-2697); 168; 141-147
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  • 4
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 69-75
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  • 5
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 6-17
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  • 6
    Publication Date: 2011-08-19
    Description: Previous work on the mass transport rate of the GeSe-GeI4 system has been reevaluated using the mass spectrometric results of Buchan and Rosenberger (1987), and considering the presence of GeSe(s) and GeSe2(s) phases in the source material. The present transport rate study confirms the previously derived dominance of the sublimation of GeSe at lower pressures of GeI4, and of chemical vapor transport at higher pressures of GeI4. It is noted that experimentally observed flux anomalies are model-independent.
    Keywords: MATERIALS PROCESSING
    Type: Journal of Crystal Growth (ISSN 0022-0248); 89; 2-3,; 242-250
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  • 7
    Publication Date: 2011-08-19
    Description: The effects of growth parameters on the thermal distribution during a Bridgman-Stockbarger-type crystal growth of HgCdTe alloys using short gradient zones are analyzed numerically. The analysis takes into account the change in the thermophysical properties upon freezing and considers both the temperature and composition dependences of the properties as well as translation rate effects. The calculated results compare favorably with previously published empirical results.
    Keywords: MATERIALS PROCESSING
    Type: Journal of Crystal Growth (ISSN 0022-0248); 86; 1-4,
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  • 8
    Publication Date: 2011-08-19
    Description: Interrupted growth experiments on Hg(0.8)Cd(0.2)Se alloys were performed in an attempt to estimate the actual internal temperature gradient in the melt during directional solidification. The results have been analyzed in terms of a theoretical model which assumes an axial composition profile characteristic of diffusion controlled solute redistribution during growth. A comparison of the calculated and measured values suggests a reduction in the applied (empty furnace) temperature gradient by about a factor of three. Values of the interface segregation coefficient (k) determined from the phase diagram, predict values of solute concentration build up in the solid during growth interruptions which are inconsistent with measured results. It appears that the k values used tend to underestimate the actual k values for higher alloy compositions and overestimate k for the lower alloy compositions.
    Keywords: MATERIALS PROCESSING
    Type: Journal of Crystal Growth (ISSN 0022-0248); 86; 1-4,; 100-105
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  • 9
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 26; 52-56
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  • 10
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 26; 1450-145
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  • 11
    Publication Date: 2011-08-19
    Description: A computational procedure is presented to simulate transonic unsteady flows and corresponding aeroelasticity of wings at low-supersonic freestreams. The flow is modeled by using the transonic small-perturbation theory. The structural equations of motions are modeled using modal equations of motion directly coupled with aerodynamics. Supersonic freestreams are simulated by properly accounting for the boundary conditions based on pressure waves along the flow characteristics in streamwise planes. The flow equations are solved using the time-accurate, alternating-direction implicit finite-difference scheme. The coupled aeroelastic equations of motion are solved by an integration procedure based on the time-accurate, linear-acceleration method. The flow modeling is verified by comparing calculations with experiments for both steady and unsteady flows at supersonic freestreams. The unsteady computations are made for oscillating wings. Comparisons of computed results with experiments show good agreement. Aeroelastic responses are computed for a rectangular wing at Mach numbers ranging from subtransonic to upper-transonic (supersonic) freestreams. The extension of the transonic dip into the upper transonic regime is illustrated.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 955-961
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  • 12
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 897-903
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  • 13
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 875-881
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  • 14
    Publication Date: 2011-08-19
    Description: Low-gravity work is reviewed and various factors influencing phase distribution are analyzed. The behavior of miscibility gap type materials in low gravity is studied. The nature of the attraction between the solution and the container or surface affects the volume of the minority phase available to form dispersed droplets as well as the extent of undercooling of the monotectic reaction.
    Keywords: MATERIALS PROCESSING
    Type: Res Mechanica (ISSN 0143-0084); 24; 277-297
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  • 15
    Publication Date: 2011-08-19
    Description: The effect of a simulated glaze-ice accretion on the aerodynamic performance of a NACA 0012 airfoil was studied experimentally. Two ice shapes were tested: one from an experimentally measured accretion, and one from an accretion predicted using a computer model given the same icing conditions. Lift, drag, and pitching moment were measured for the airfoil with both smooth and rough ice shapes. The ice shapes caused large lift and drag penalties, primarily due to large separation bubbles. Surface pressure distributions clearly showed the regions of separated flow. The aerodynamic performance of the two shapes compared well at positive, but not negative, angles of attack.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 849-854
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  • 16
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 820-826
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  • 17
    Publication Date: 2011-08-19
    Description: Hypermonotectic copper-lead alloys were directionally solidified at unit gravity on earth and also in the cyclic gravitational environment attainable during flight of NASA's KC-135 aircraft. In both cases macrosegregation developed that consisted of an initial lead-rich phase above which an aligned composite structure of apparent monotectic composition grew. Differences within these regions are examined, and the suitability of the KC-135 environment for directional solidification of monotectic alloys is discussed.
    Keywords: MATERIALS PROCESSING
    Type: Metallurgical Transactions A - Physical Metallurgy and Materials Science (ISSN 0360-2133); 19A; 2677-268
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  • 18
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 349-354
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  • 19
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 355-363
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  • 20
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 302-310
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  • 21
    Publication Date: 2011-08-19
    Description: A directionally solidified PbCl2 material was prepared and analyzed and subsequently used to grow single crystals. It was found that silicon, halogens, sulfur, magnesium, and phosphorus were the hardest impurities to remove by the single-pass directional freezing. Single crystals grown from the purified material displayed good scattering beam quality and showed no absorption peaks between 0.30 to 20 microns. Direct photographic observations of the solid-liquid interface at several G/V (denoting the temperature gradient and the translation velocity, respectively) ratio values showed that, as the G/V ratio decreased, the interface varied from a smooth convex surface to dendritic.
    Keywords: MATERIALS PROCESSING
    Type: Journal of Crystal Growth (ISSN 0022-0248); 89; 1, Ju
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  • 22
    Publication Date: 2011-08-19
    Description: The drag of airfoils in transonic flow can be reduced through the use of a passive venting system that employs a porous plate for part of the airfoil upper surface with a vent chamber underneath the porous plate Attention is given to the results obtained with a wind tunnel model employing such a porous floor system. This passive venting system has been used to extend the length/height value before the onset of high drag-producing closed cavity flow at supersonic speeds.
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 26; 374-376
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  • 23
    Publication Date: 2011-08-19
    Description: The wakes of highly loaded compressor blades are generally considered to be turbulent flows. Recent work has suggested that the blade wakes are dominated by a vortex streetlike structure. The experimental evidence supporting the wake vortex structure is reviewed. This structure is shown to redistribute thermal energy within the flowfield. The effect of the wake structure on conventional aerodynamic measurements of compressor performance is noted. A two-dimensional, time-accurate, viscous numerical simulation of the flow exhibits both vortex shedding in the wake and a lower-frequency flow instability that modulates the shedding. The numerical results are shown to agree quite well with the measurement from transonic compressor rotors.
    Keywords: AERODYNAMICS
    Type: Journal of Propulsion and Power (ISSN 0748-4658); 4; 236-244
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  • 24
    Publication Date: 2011-08-19
    Description: Studies to examine the effect of solutal convection on crystal morphology using sucrose as a model system were initiated. Aspect ratios, defined as the width of the 100-plane-oriented face over the width of the 001-plane-oriented face, were determined for oriented crystals which were grown with either the 001-oriented or the 100-oriented face perpendicular to the convective flow. The dependence of the crystal morphology on orientation is much greater for crystals grown with one face occluded than for crystals grown suspended in solution. Many factors appear to interact in a complex fashion to influence crystal morphology.
    Keywords: MATERIALS PROCESSING
    Type: Journal of Crystal Growth (ISSN 0022-0248); 90; 1-3,
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  • 25
    Publication Date: 2011-08-19
    Description: The effects of mean-flow incidence, airfoil camber, and airfoil thickness on the incompressible aerodynamics of an oscillating airfoil are investigated theoretically, developing and applying a first-order FEM based on locally analytical solutions (LASs). Laplace equations are used to describe the steady and unsteady harmonic velocity potentials; a body-fitted computational grid is employed; grid-element solutions for both potentials are determined using a numerical LAS method; and the LASs are then assembled to obtain a complete solution. Results for a series of flat-plate and Joukowski airfoils are presented in extensive graphs and discussed in detail.
    Keywords: AERODYNAMICS
    Type: International Journal for Numerical Methods in Fluids (ISSN 0271-2091); 8; 913-931
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  • 26
    Publication Date: 2011-08-19
    Description: Scientists at the NASA White Sands Test Facility (WSTF) are investigating the relationship between outgassing and condensation for aerospace materials in space-like environments. The WSTF throughput test method was validated by previous testing at WSTF using palmitic acid. Data from these tests were compared with data from other preliminary tests by using adipic and behenic acids. The comparison indicates that surface forces between outgassed molecules and the condensing surfaces cause the condensation flux to be different from the incident flux. These forces can also cause the evaporative flux to be different from the expected value. These discrepancies are discussed in terms of both potential and dynamic interactions of outgassed molecules with surfaces. Although these surface forces are noticeable, their overall effect on the test is minimal.
    Keywords: MATERIALS PROCESSING
    Type: Journal of Environmental Sciences (ISSN 0022-0906); 31; 28-32
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  • 27
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 26; 824-831
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  • 28
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 26; 649-654
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  • 29
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 25; 24-30
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  • 30
    Publication Date: 2011-08-19
    Description: A series of Hg(0.8)Cd(0.2)Te ingots was cast both vertically and horizontally under well-defined thermal conditions by using a two-zone furnace with isothermal heat-pipe liners. The main objective of the experiments was to establish correlations between casting parameters and compositional redistribution and to develop ground-based data for a proposed flight experiment of casting of Hg(1-x)Cd(x)Te alloys under reduced gravity conditions. The compositional variations along the axial and radial directions were determined by precision density measurements, infrared transmission spectra, and X-ray energy dispersion spectrometry. Comparison between the experimental results and a numerical simulation of the solidification process of Hg(0.8)Cd(0.2)Te is described.
    Keywords: MATERIALS PROCESSING
    Type: Journal of Crystal Growth (ISSN 0022-0248); 91; 1-2,; 20-26
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  • 31
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 25; 217-224
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  • 32
    Publication Date: 2011-08-19
    Keywords: MATERIALS PROCESSING
    Type: Metallurgical Transactions A - Physical Metallurgy and Materials Science (ISSN 0360-2133); 19A; 1915-191
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  • 33
    Publication Date: 2011-08-19
    Description: In support of the surface tension driven convection experiment planned for flight aboard the Space Shuttle, tests were conducted under reduced gravity in the 2.2-sec drop tower and the 5.0-sec Zero-G facility at the Lewis Research Center. The dynamics of controlling the test fluid, a 10-centistoke viscosity silicone fluid, in a low-gravity environment were investigated using different container designs and barrier coatings. Three container edge designs were tested without a barrier coating: a square edge, a sharp edge with a 45-deg slope, and a saw-tooth edge. All three edge designs were successful in containing the fluid below the edge.
    Keywords: MATERIALS PROCESSING
    Type: Metallurgical Transactions A - Physical Metallurgy and Materials Science (ISSN 0360-2133); 19A; 1883-188
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  • 34
    Publication Date: 2011-08-19
    Description: Part of the microgravity science to be conducted aboard the Shuttle (STS) involves combustion using solids, particles, and liquid droplets. The central experimental facts needed for characterization of premixed quiescent particle cloud flames cannot be adequately established by normal gravity studies alone. The experimental results to date of acoustically mixing a prototypical particulate, lycopodium, in a 5 cm diameter by 75 cm long flame tube aboard a Learjet aircraft flying a 20-sec low-gravity trajectory are described. Photographic and light detector instrumentation combine to measure and characterize particle cloud uniformity.
    Keywords: MATERIALS PROCESSING
    Type: Metallurgical Transactions A - Physical Metallurgy and Materials Science (ISSN 0360-2133); 19A; 1931-193
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  • 35
    Publication Date: 2011-08-19
    Description: Fifty different mineral samples were tested as potential heterogeneous or epitaxial nucleants for four commonly crystallized proteins. It was found, using conventional protein crystallization techniques, that for each protein there was a set of mineral substrates that promoted nucleation of crystals at lower critical levels of supersaturation than required for spontaneous growth. In at least one case, the growth of lysozyme on the mineral apophyllite, it was shown by lattice analysis and X-ray diffraction that the nucleation and growth of the protein crystal on the mineral was likely to be truly epitaxial.
    Keywords: MATERIALS PROCESSING
    Type: Journal of Crystal Growth (ISSN 0022-0248); 90; 1-3,
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  • 36
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 675
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  • 37
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 673
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  • 38
    Publication Date: 2011-08-19
    Description: A complete mathematical model is formulated to analyze the effects of mean-flow incidence angle on the unsteady aerodynamics of an oscillating airfoil in an incompressible flow field. A velocity potential formulation is utilized. The steady flow is independent of the unsteady flow field but coupled to it through the boundary conditions on the oscillating airfoil. The numerical solution technique for both the steady and unsteady flow fields is based on a locally analytical method. The flow model and solution method are then verified through the excellent correlation obtained with the Theodorsen oscillating-flat-plate and Sears transverse-gust classical solutions. The effects of mean flow incidence on the steady and oscillating airfoil aerodynamics are then investigated.
    Keywords: AERODYNAMICS
    Type: International Journal for Numerical Methods in Engineering (ISSN 0029-5981); 26; 2227-223
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  • 39
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 598-605
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  • 40
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 26; 553-560
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  • 41
    Publication Date: 2011-08-19
    Description: Computational results are presented for the transitional or turbulent flow about a prolate spheroid, at alpha = 10 deg or 30 deg, correspondingly, using an implicit, approximately factored, partially flux-split algorithm, based on the thin-layer equations. The computed flow field is in good agreement with available experimental data.
    Keywords: AERODYNAMICS
    Type: Zeitschrift fuer Flugwissenschaften und Weltraumforschung (ISSN 0342-068X); 12; 173-180
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  • 42
    Publication Date: 2011-08-19
    Description: A series of preliminary experiments were done to investigate solutal flow about growing lysozyme crystals and its effects. Density-gradient-driven flow was observed using a schlieren optical system. Crystals used ranged from 0.3 to 1.72 mm across the (110) face, and protein concentrations were from 3.7 to 23.7 mg/ml. The convective plume velocities were found to be from 10 to 50 microns/s, which correlated with those predicted to occur based upon a diffusive-convective model. When microcrystals of lysozyme, less than 20 microns across the (110) face were subjected to directed solution flows, the growth rate was found to rapidly decrease over the 8-20 h course of the experiment. Solution flow rates used ranged from 18 to 40 microns/s, and protein concentrations were from 7.3 to 11.7 mg/ml, conditions typical of larger (greater than 0.5 mm) crystals in the terminal phases of a typical crystal growth procedure.
    Keywords: MATERIALS PROCESSING
    Type: Journal of Crystal Growth (ISSN 0022-0248); 90; 1-3,
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  • 43
    Publication Date: 2011-08-19
    Description: Thin-element riblets for aircraft aerodynamic surface turbulent viscous drag reduction are presently found to be as effective as symmetric V-grooves in this role, while possessing a greater range of admissible spacings. The thin-element geometry shows the qualitatively predictable influence of independent riblet height and spacing variations. The evidence for more than one drag-reduction mechanism in thin-element riblets is found to be inconclusive.
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 26; 496-498
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  • 44
    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 26; 392
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  • 45
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    Publication Date: 2011-08-19
    Description: This paper briefly reviews some national studies and new programs concerning hypersonic flight. The flight environment that will be encountered by this new class of hypersonic vehicles is described, and the fluid-dynamic and chemical phenomena that occur in hypersonic flight are examined. Ground-based facilities are briefly described, and their use in helping to validate the codes is examined.
    Keywords: AERODYNAMICS
    Type: Communications in Applied Numerical Methods (ISSN 0748-8025); 4; 319-325
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  • 46
    Publication Date: 2011-08-19
    Description: A series of Hg(1-x)Zn(x)Te crystals were grown by directional solidification with x ranging from 0.15 to 0.22. The axial and radial compositional variations were determined by precision density measurements, infrared (IR) transmission spectra, and energy dispersive X-ray spectroscopy (EDX). Comparison between the axial compositional profiles and the calculated results of a one-dimensional diffusion model gives a value for the effective diffusion coefficient in the HgZnTe melt of 2 to 4 x 10 to the -6th sq cm/s.
    Keywords: MATERIALS PROCESSING
    Type: Journal of Crystal Growth (ISSN 0022-0248); 86; 1-4,; 87-92
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  • 47
    Publication Date: 2011-08-19
    Keywords: MATERIALS PROCESSING
    Type: AIAA Journal (ISSN 0001-1452); 26; 34-39
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  • 48
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    Publication Date: 2011-08-19
    Description: Different models for inviscid transonic flows are examined. The common assumptions that the flow is isentropic and irrotational are critically evaluated. Entropy and vorticity correction procedures for potential and stream function formulations are presented, together with the details of the treatment of shocks and wakes, and drag and lift calculations. The non-uniqueness problem of the potential formulation is studied using different artificial viscosity forms. Numerical results are compared with Euler solutions.
    Keywords: AERODYNAMICS
    Type: International Journal for Numerical Methods in Fluids (ISSN 0271-2091); 8; 31-53
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  • 49
    Publication Date: 2013-08-31
    Description: Low-speed wind tunnel drag force measurements were taken on a laminar flow body of revolution free of support interference. This body was tested at zero incidence in the NASA Langley 13 inch Magnetic Suspension and Balance System (MSBS). The primary objective of these tests was to substantiate the drag force measuring capabilities of the 13 inch MSBS. A secondary objective was to obtain support interference free drag measurements on an axisymmetric body of interest. Both objectives were met. The drag force calibrations and wind-on repeatability data provide a means of assessing the drag force measuring capabilities of the 13 inch MSBS. The measured drag coefficients for this body are of interest to researchers actively involved in designing minimum drag fuselage shapes. Additional investigations included: the effects of fixing transition; the effects of fins installed in the tail; surface flow visualizations using both liquid crystals and oil flow; and base pressure measurements using a one-channel telemetry system. Two drag prediction codes were used to assess their usefulness in estimating overall body drag. These theoretical results did not compare well with the measured values because of the following: incorrect or non-existent modeling of a laminar separation bubble on the body and incorrect of non-existent estimates of base pressure drag.
    Keywords: AERODYNAMICS
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  • 50
    Publication Date: 2013-08-31
    Description: It is observed that the center of pressure on a wing shifts as the Mach number is changed. Such shifts are in general undesirable and are sometimes compensated for by actively shifting the center of gravity of the aircraft or by using active stability controls. To avoid this complication, it is desirable to design the wings of a high speed aircraft so as to minimize the extent of the center-of-pressure shifts. This, together with a desire to minimize the center-of-pressure shifts in missile control surfaces, provides the motivation for this project. There are many design parameters which affect center-of-pressure shifts, but it is expected that the largest effects are due to the wing planform. Thus, for the sake of simplicity, this study is confined to an investigation of thin, flat, (i.e., no camber or twist), relatively slender, pointed wings flying at a small angle of attack. Once the dependence of the center of pressure on planform and Mach number is understood, we can expect to investigate the sensitivity of the center-of-pressure shifts to various other parameters.
    Keywords: AERODYNAMICS
    Type: Hampton Inst., NASA/American Society for Engineering Educ; Hampton Inst., NASA(
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  • 51
    Publication Date: 2013-08-31
    Description: Within the last two decades, there has been increasing emphasis on developing more sophisticated computational fluid dynamics (CFD) methods to handle a wide range of problems of interest to the aerospace community. The comprehensive picture of the status of CFD development and capability as well as an assessment of requirements and future directions are given. An independent review and assessment was also carried out by the author as part of the current assignment and the results are outlined herein.
    Keywords: AERODYNAMICS
    Type: Hampton Inst., NASA/American Society for Engineering Educ; Hampton Inst., NASA(
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  • 52
    Publication Date: 2013-08-31
    Description: The Controlled Ecological Life Support System (CELSS) project, sponsored by NASA, is assembling the knowledge required to design, construct, and operate a system which will grow and process higher plants in space for the consumption by crew members of a space station on a long term space mission. The problem of processing dry granular organic materials in microgravity is discussed. For the purpose of research and testing, wheat was chosen as the granular material to be ground into flour. Possible systems which were devised to transport wheat grains into the food processor, mill the wheat into flour, and transport the flour to the food preparation system are described. The systems were analyzed and compared and two satisfactory systems were chosen. Prototypes of the two preferred systems are to be fabricated next semester. They will be tested under simulated microgravity conditions and revised for maximum effectiveness.
    Keywords: MATERIALS PROCESSING
    Type: Advanced Space Design Program to the Universities Space Research Association and the National Aeronautics and Space Administration; 20 p
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  • 53
    Publication Date: 2013-08-31
    Description: Two dimensional problems are solved using numerical techniques. Navier-Stokes equations are studied both in the vorticity-stream function formulation which appears to be the optimal choice for two dimensional problems, using a storage approach, and in the velocity pressure formulation which minimizes the number of unknowns in three dimensional problems. Analysis shows that compact centered conservative second order schemes for the vorticity equation are the most robust for high Reynolds number flows. Serious difficulties remain in the choice of turbulent models, to keep reasonable CPU efficiency.
    Keywords: AERODYNAMICS
    Type: VKI, Unsteady Aerodynamics, Volume 2; 120 p
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  • 54
    Publication Date: 2013-08-31
    Description: Crystal nucleation measurements were made on three lithium borate compositions in the vicinity of Li2O-2Br2O3. All nucleation measurements were performed at 500 C. Certain aspects of the nucleation behavior indicated (tentatively) that it proceeded by a homogeneous mechanism. The steady state nucleation rate was observed to have the largest value when the Li2O concentration was slightly in excess of the diborate composition. The change in nucleation rate with composition is controlled by the variation of viscosity as well as the change in free energy with composition. The variation of nucleation rate is explained qualitatively in these terms.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 2; p 569-591
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  • 55
    facet.materialart.
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    In:  CASI
    Publication Date: 2013-08-31
    Description: Fluoride glass was levitated acoustically in the ACES apparatus on STS-11, and the recovered sample had a different microstructure from samples cooled in a container. Further experiments on levitated samples of fluoride glass are proposed. These include nucleation, crystallization, melting observations, measurement of surface tension of molten glass, and observation of bubbles in the glass. Ground experiments are required on sample preparation, outgassing, and surface reactions. The results should help in the development and evaluation of containerless processing, especially of glass, in the development of a contaminent-free method of measuring surface tensions of melts, in extending knowledge of gas and bubble behavior in fluoride glasses, and in increasing insight into the processing and properties of fluoride glasses.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 2; p 525-535
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  • 56
    Publication Date: 2013-08-31
    Description: Eutectic alloys of Bi-Mn were directionally solidified using the Bridgman-Stockbarger technique to determine the influences of gravitationally-driven thermo-solutal convection on the Bi-MnBi rod eutectic. Experiments were conducted that varied the level of convection by varying the growth parameters and growth orientation, by microgravity damping, by applied magnetic field damping, and by imposing forced convection. Peltier interface demarcation and in situ thermocouple measurements were used to monitor interface velocity and thermal gradient and to evaluate interface planarity.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 1; p 485-510
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  • 57
    Publication Date: 2013-08-31
    Description: The Casting and Solidification Technology (CAST) experiment will study the phenomena that occur during directional solidification of an alloy, e.g., constitutional supercooling, freckling, and dendrite coarsening. The reduced gravity environment of space will permit the individual phenomena to be examined with minimum complication from buoyancy driven flows.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 1; p 459-467
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  • 58
    Publication Date: 2013-08-31
    Description: The principal objectives of this overall investigation are to: study means for obtaining high undercooling in levitation melted droplets, and study structures produced upon the solidification of these undercooled specimens. Thermal measurements are made of the undercooling, and of the rapid recalescence, to develop an understanding of the solidification mechanism. Comparison of results is made with the modeling studies. Characterization and metallographic work is done to gain an understanding of the relationship between rapid solidification variables and the structures so produced. In ground based work to date, solidification of undercooled Ni-25 wt percent Sn alloy was observed by high-speed cinematography and the results compared with optical temperature measurements. Also in ground based work, high-speed optical temperature measurements were made of the solidification behavior of levitated metal samples within a transparent glass medium. Two undercooled Ni-Sn alloys were examined. Measurements were carried out on samples at undercoolings up to 330 K. Microstructures of samples produced in ground based work were determined by optical metallography and by SEM, and microsegregation by electron microprobe measurements. A series of flight tests were planned to conduct experiments similar to the ground based experiments. The Space Shuttle Columbia carried an alloy undercooled experiment in the STS 61-C mission in January 1986. A sample of Ni-32.5 wt percent Sn eutectic was melted and solidified under microgravity conditions.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 1; p 469-483
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  • 59
    facet.materialart.
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    In:  CASI
    Publication Date: 2013-08-31
    Description: Experiments are recounted that test the effects of microgravity on cells, from the 60's up to the present. Results of these experiments are briefly discussed.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 1; p 217-226
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  • 60
    Publication Date: 2013-08-31
    Description: Flight experiments are planned on drops containing bubbles. The experiments involve stimulating the drop via non-uniform heating and rotation. The resulting trajectories of the bubbles as well as the shapes of the drops and bubble will be videotaped and analyzed later frame-by-frame on the ground. Supporting ground based experiments are planned in the area of surface tension driven motion of bubbles, the behavior of compound drops settling in an immiscible liquid and the shapes and trajectories of large bubbles and drops in a rotating liquid. Theoretical efforts will be directed at thermocapillary migration of drops and bubbles, surfactant effects on such migration, and the behavior of compound drops.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 2; p 593-603
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  • 61
    Publication Date: 2013-08-31
    Description: The near weightlessness of a material in the reduced gravity environment of space offers the opportunity of melting and cooling glass forming compositions without a container. This reduces the heterogeneous nucleation/crystallization which usually occurs at the walls of the container, thereby, extending the range of glass forming compositions. Based primarily on this idea, containerless glass forming experiments, which used a single axis acoustic levitator/furnace (SAAL), were conducted on SPAR rocket flights, 6 and 8, and on Space Shuttle mission, STS-7 and STS-61A. The experiments on the Space Shuttle were designed to include other studies related to melt homogenization and mixing, development of techniques for preparing uncontaminated preflight samples, and simple shaping experiments.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 2; p 537-556
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  • 62
    Publication Date: 2013-08-31
    Description: The Isothermal Dendritic Growth Experiment is an active crystal growth experiment designed to test dendritic growth theory at low undercoolings where convection prohibits such studies at 1 g. The experiment will be essentially autonomous, though limited in-flight interaction through a computer interface is planned. One of the key components of the apparatus will be a crystal growth chamber capable of achieving oriented single crystal dendritic growth. Recent work indicates that seeding the chamber with a crystal of the proper orientation will not, in and of itself, be sufficient to meet this requirement. Additional flight hardware and software required for the STS flight experiment are currently being developed at NASA Lewis Research Center and at Rensselaer Polytechnic Institute.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 1; p 411-425
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  • 63
    Publication Date: 2013-08-31
    Description: Based on the thermophysical properties of Hg sub 1-x Cd sub x Te alloys, the reasons are discussed for the failure of conventional Bridgman-Stockbarger growth methods to produce high quality homogeneous crystals in the prescence of Earth's gravity. The deleterious effects are considered which arise from the dependence of the thermophysical properties on temperature and composition and from the large amount of heat carried by the fused silica ampules. An improved growth method, developed to optimize heat flow conditions, is described and experimental results are presented. The problems associated with growth in a gravitational environment are discussed. The anticipated advantages of growth in microgravity are given and the implications of the requirements for spaceflight experiments are summarized.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 1; p 377-390
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  • 64
    Publication Date: 2013-08-31
    Description: Specific T cell clones and antibodies (ABs) were developed to study the efficiency of purifying closely associated T cells using Continuous Flow Electrophoresis System. Enhanced separation is accomplished by tagging cells first with ABs directed against the antigenic determinants on the cell surface and then with ABs against the Fc portion of the first AB. This second AB protrudes sufficiently beyond the cell membrane and glycocalyx to become the major overall cell surface potential determinant and thus causes a reduction of electrophoretic mobility. This project was divided into three phases. Phase one included development of specific T cell clones and separation of these specific clones. Phase two extends these principles to the separation of T cells from spleen cells and immunized lymph node cells. Phase three applies this double antibody technique to the separation of T cytotoxic cells from bone marrow.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 1; p 227-234
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  • 65
    Publication Date: 2013-08-31
    Description: Phase separated solutions of two neutral polymers in buffer provide a useful and versatile medium for the partition separation of biological cells. However, the efficiency of such separations is orders of magnitude lower than the thermodynamic limit. To test the hypothesis that this inefficiency is at least partially due to the convection and sedimentation that occur during the gravity driven demixing that follows introduction of cells to the systems, a series of experiments were begun aimed at performing cell partition in a low g environment. Demixing of isopycnic three polymer solvent systems was studied, experiments were performed on KC-135 aircraft and one shuttle middeck experiment was completed. Analysis of the results of these experiments and comparisons with the predictions of scaling relations for the dependence of phase domain size on time, derived for a number of possible demixing mechanisms, are presented.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 1; p 119-131
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  • 66
    Publication Date: 2013-08-31
    Description: The cell separation techniques of velocity sedimentation, flow cytometry and continuous flow electrophoresis were used to obtain enriched populations of growth hormone (GH) cells. The goal was to isolate a GH cell subpopulation which releases GH molecules which are very high in biological activity, it was important to use a method which was effective in processing large numbers of cells over a short time span. The techniques based on sedimentation are limited by cell density overlaps and streaming. While flow cytometry is useful in the analytical mode for objectively establishing cell purity, the numbers of cells which can be processed in the sort mode are so small as to make this approach ineffective in terms of the long term goals. It was shown that continuous flow electrophoresis systems (CFES) can separate GH cells from other cell types on the basis of differences in surface charge. The bioreactive producers appear to be more electrophoretically mobile than the low producers. Current ground based CFES efforts are hampered by cell clumping in low ionic strength buffers and poor cell recoveries from the CFES device.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 1; p 47-88
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  • 67
    Publication Date: 2013-08-31
    Description: Supersonic external compression inlets are introduced, and the computational fluid dynamics (CFD) codes and tests needed to study flow associated with these inlets are outlined. Normal shock wave turbulent boundary layer interaction is discussed. Boundary layer control is considered. Glancing sidewall shock interaction is treated. The CFD validation of hypersonic inlet configurations is explained. Scramjet inlet modules are shown.
    Keywords: AERODYNAMICS
    Type: VKI, Intake Aerodynamics, Volume 2; 62 p
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  • 68
    Publication Date: 2013-08-31
    Description: The fluid dynamics of curved diffuser duct flows of military aircraft is discussed. Three-dimensional parabolized Navier-Stokes analysis, and experiment techniques are reviewed. Flow measurements and pressure distributions are shown. Velocity vectors, and the effects of vortex generators are considered.
    Keywords: AERODYNAMICS
    Type: VKI, Intake Aerodynamics, Volume 2; 59 p
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  • 69
    Publication Date: 2013-08-31
    Description: Fundamental equations encountered in computational fluid dynamics (CFD), and analyses used for internal flow are introduced. Irrotational flow; Euler equations; boundary layers; parabolized Navier-Stokes equations; and time averaged Navier-Stokes equations are treated. Assumptions made and solution methods are outlined, with examples. The overall status of CFD in propulsion is indicated.
    Keywords: AERODYNAMICS
    Type: VKI, Intake Aerodynamics, Volume 2; 43 p
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  • 70
    Publication Date: 2013-08-31
    Description: Induced disturbance sources have been identified on board the Man Tended Free Flyer (MTFF). Vibration responses at sensitive payload/spacecraft interfaces have been predicted by the application of an empirically found spacecraft dynamic transfer function. Vibrations from fluid loops (Freon, water) and of reaction wheels are assessed to be the main contributors to the induced microgravity environment. The expected payload acceleration response amplitudes presented here are more than one hundred times higher than the admissible values given by the MTFF system requirement, not considering the structural striction-friction effects which could be avoided by appropriate design. Real responses will be significantly lower because the derivation of excitation and transmission functions are based on worst case assumptions. The results indicate that future activities must be concentrated on equipment design improvement and the implementation of vibration reduction along the disturbance transmission path. The activities must be accompanied by early equipment and assembly development tests and transmissibility measurements with the integrated spacecraft engineering and structural models in order to improve the accuracy of payload response predictions.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Goddard Space Flight Center, 15th Space Simulation Conference: Support the Highway to Space Through Testing; p 289-307
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  • 71
    Publication Date: 2013-08-31
    Description: The objective is to develop an accurate dynamic technique which, in a microgravity environment, would enable performance of thermophysical measurements on high-melting-point electrically conducting substances in their liquid state. In spite of the critical need in high temperature technologies related to spacecraft, nuclear reactors, effects of power laser radiation, and in validating theoretical models in related areas, no accurate data on thermophysical properties exist. This is primarily due to the limitation of the reliable steady-state techniques to temperatures below about 2000 K, and the accurate millisecond-resolution pulse heating techniques to the solid state of the specimen. The limitation of the millisecond-resolution techniques to temperatures below the melting point stems from the fact that the specimen collapses due to the gravitational force once it starts to melt. The rationale for the use of the microgravity is that by performing the dynamic experiments in a microgravity environment the specimen will retain its geometry, and thus it will be possible to extend the accurate thermophysical measurements to temperatures above the melting point of high-melting-point substances.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 2; p 763-771
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  • 72
    Publication Date: 2013-08-31
    Description: The current work involves theoretical analyses of the effects identified, experiments in the NASA Lewis drop towers performed in the middeck areas of the Space Shuttle. In addition, there is laboratory work associated with the design of the flight apparatus. Calculations have shown that some of the test-matrix data can be obtained in drop towers, and some are achievable only in the space experiments. The apparatus consists of a droplet dispensing device (syringes), a droplet positioning device (opposing, retractable, hollow needles), a droplet ignition device (two matched pairs of retractable spark electrodes), gas and liquid handling systems, a data acquisition system (mainly giving motion-picture records of the combustion in two orthogonal views, one with backlighting for droplet resolution), and associated electronics.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 2; p 675-691
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  • 73
    Publication Date: 2013-08-31
    Description: Investigations were established for the purpose of analyzing the conditioned media from human embryonic kidney cell subpopulations separated in space by electrophoresis. This data is based on the experiments performed on STS-8 on the continuous flow electrophoresis system. The primary biological activity that was analyzed was plasminogen activator activity, but some assays for erythropoeitin and human granulocyte colony stimulating activity were also performed. It is concluded that a battery of assays are required to completely define the plasminogen activator profile of a conditioned media from cell culture. Each type of assay measures different parts of the mixture and are influenced by different parameters. The functional role of each assay is given along with an indication of which combination of assays are required to answer specific questions. With this type of information it is possible by combinations of assays with mathematical analysis to pinpoint a specific component of the system.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 1; p 175-193
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  • 74
    Publication Date: 2013-08-31
    Description: An expert system based intelligent control scheme is being developed for the effective control and full automation of bioreactor systems in space. The scheme developed will have the capability to capture information from various resources including heuristic information from process researchers and operators. The knowledge base of the expert system should contain enough expertise to perform on-line system identification and thus be able to adapt the controllers accordingly with minimal human supervision.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 1; p 159-162
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  • 75
    Publication Date: 2013-08-31
    Description: A premise of continuous flow electrophoresis is that removal of buoyance-induced thermal convection caused by axial and lateral temperature gradients results in ideal performance of these instruments in space. Although these gravity dependent phenomena disturb the rectilinear flow in the separation chamber when high voltage gradients or thick chamber are used, distortion of the injected sample stream due to electrodynamic effects cause major broadening of the separated bands. The electrophoresis separation process is simple, however flow local to the sample filament produced by the applied electric field were not considered. These electrohydrodynamic flows distort the sample stream and limit the separation. Also, electroosmosis and viscous flow combine to further distort the process. A moving wall concept is being proposed for space which will eliminate and control the disturbances. The moving wall entrains the fluid to move as a rigid body and produces a constant residence time for all samples distributed across the chamber thickness. The moving wall electrophoresis chamber can only be operated in space because there is no viscous flow in the chamber to stabilize against thermal convection.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 1; p 27-46
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  • 76
    facet.materialart.
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    In:  CASI
    Publication Date: 2013-08-31
    Description: The motivation and potential for performing very high resolution measurements of the heat capacity singularity at the lambda point of helium in microgravity conditions was briefly discussed. It is clear that tests extending deep into the asymptotic region can be performed, where the theoretical predictions take on their simplest form. This advantageous situation should lead to a major improvement in the understanding of the range of applicability of current theoretical ideas in this field. The lambda transition holds out the prospect of giving the maximum advance of any system, and with the application of cryogenic techniques, the potential of this system can be realized. The technology for the initial experiments is already developed, and results could be obtained in 1990.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 2; p 791-803
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  • 77
    Publication Date: 2013-08-31
    Description: The behavior of rotating and oscillating free liquid drops was studied by many investigators theoretically for many years. More recent numerical treatments have yielded predictions which are yet to be verified experimentally. The purpose is to report the results of laboratory work as well as that of the experiments carried out in space during the flight of Spacelab 3, and to compare it with the existing theoretical studies. Ground-based experiments were attempted as a first approximation to the ideal boundary conditions used by the theoretical treatments by neutralizing the overwhelming effects of the Earth's gravitational field with an outside supporting liquid and with the use of levitation technology. The viscous and inertial loading of such a suspending fluid was found to profoundly effect the results, but the information thus gathered has emphasized the uniqueness of the experimental data obtained in the low-gravity environment of space.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 2; p 739-761
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  • 78
    Publication Date: 2013-08-31
    Description: Thermocapillary flow is driven by a thermally induced surface tension variation along a liquid free surface. In the Earth-gravity environment such flows are usually overshadowed by buoyancy driven flows, but at reduced gravity conditions their influence could be significant. A comprehensive theoretical and experimental research program was stated 12 years ago and is still being continued. Past work done at Case Western Reserve University as well as work done by others is reviewed. The justification for low-gravity experiments is presented.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 2; p 695-713
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  • 79
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2013-08-31
    Description: The prinicipal objectives of this microgravity experiment program are to obtain flame propagation rate and flame extinction limit data for several important premixed, quiescent particle cloud combustion systems under near zero-gravity conditions. The data resulting from these experiments are needed for utilization with currently available and tractable flame propagation and extinction theory. These data are also expected to provide standards for the evaluation of fire hazards in particle suspensions in both Earth-based and space-based applications. Both terrestrial and space-based fire safety criteria require the identification of the critical concentrations of particulate fuels and inerts at the flame extinction conditions.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 2; p 605-641
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  • 80
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2013-08-31
    Description: The Get Away Special 611 (GAS-611) project will carry a small, self-contained biological experiment into a microgravity environment for a period of 120 hours. The payload will be a colony of Lampyridae (fireflies). The ability of this beetle to produce light with an efficiency of 98 pct will be evaluated in the micro-G environment. The chemical process that occurs could be assisted by the earth's gravitational pull and the very complex tracheae system found within this species of beetle. The effects of microgravity on mating and beetle larvae will also be studied.
    Keywords: MATERIALS PROCESSING
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  • 81
    Publication Date: 2013-08-31
    Description: One of the flows inherent in VSTOL operations, the jet in ground effect with a crossflow, is studied using the Fortified Navier-Stokes (FNS) scheme. Through comparison of the simulation results and the experimental data, and through the variation of the flow parameters (in the simulation) a number of interesting characteristics of the flow have been observed. For example, it appears that the forward penetration of the ground vortex is a strong inverse function of the level of mixing in the ground vortex. Also, an effort has been made to isolate issues which require additional work in order to improve the numerical simulation of the jet in ground effect flow. The FNS approach simplifies the simulation of a single jet in ground effect, but it will be even more effective in applications to more complex topologies.
    Keywords: AERODYNAMICS
    Type: The 1987 Ground Vortex Workshop; p 191-206
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  • 82
    Publication Date: 2013-08-31
    Description: Key results from low speed wind tunnel testing of the F-15 STOL and Maneuver Technology Demonstrator (SMDT) with thrust reversers are presented. Longitudinally, the largest induced increments in the stability and control occur at landing gear height. These generally reflect an induced lift loss and a nose-up pitching moment, and vary with sideslip. Directional stability is reduced at landing gear height with full reverse thrust. Nonlinearities in the horizontal tail effectiveness are found in free air and at landing gear height.
    Keywords: AERODYNAMICS
    Type: NASA, Ames Research Center, The 1987 Ground Vortex Workshop; p 91-119
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  • 83
    Publication Date: 2013-08-31
    Description: A new testing technique was developed wherein the rate of descent can be included as a parameter in ground effects investigations. This technique simulates the rate of descent by horizontal motion of a model over an inclined ground board in the Langley Vortex Research Facility (VRF) During initial evaluations of the technique, dynamic ground effects data were obtained over the inclined ground board, steady state ground effects data were obtained over a flat portion of the ground board, and the results were compared to conventional static wind tunnel ground effect data both with and without a moving belt ground plane simulation. Initial testing and analysis led to the following conclusions: the moving belt ground plane had little effect on static ground effects for the configurations tested unless thrust reversers were employed; in general, rate-of-descent reduced ground effects to the point that for reversed thrust cases an expected loss of lift due to ground effects was eliminated at approach conditions; and, in general, the steady state results from the VRF matched static results obtained from the wind tunnel once the flow field stabilized over the flat portion of the ground board.
    Keywords: AERODYNAMICS
    Type: NASA, Ames Research Center, The 1987 Ground Vortex Workshop; p 121-146
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  • 84
    Publication Date: 2013-08-31
    Description: The results of an experimental investigation into the position and characteristics of the ground vortex are summarized. A 48-inch wind tunnel was modified to create a testing environment suitable for the ground vortex study. Flow visualization was used to document the jet-crossflow interaction and a two-component Laser Doppler Velocimeter (LDV) was used to survey the flowfield in detail. Measurements of the ground vortex characteristics and location as a function of freestream-to-jet velocity ratio, jet height, pressure gradient and upstream boundary layer thickness were obtained.
    Keywords: AERODYNAMICS
    Type: NASA, Ames Research Center, The 1987 Ground Vortex Workshop; p 39-60
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  • 85
    Publication Date: 2013-08-31
    Description: Flow field investigations were conducted at the NASA Ames-Dryden Flow Visualization Facility (water tunnel) to investigate the ground effect produced by the impingement of jets from aircraft nozzles on a ground board in a STOL operation. Effects on the overall flow field with both a stationary and a moving ground board were photographed and compared with similar data found in other references. Nozzle jet impingement angles, nozzle and inlet interaction, side-by-side nozzles, nozzles in tandem, and nozzles and inlets mounted on a flat plate model were investigated. Results show that the wall jet that generates the ground effect is unsteady and the boundary between the ground vortex flow field and the free-stream flow is unsteady. Additionally, the forward projection of the ground vortex flow field with a moving ground board is one-third less than that measured over a fixed ground board. Results also showed that inlets did not alter the ground vortex flow field.
    Keywords: AERODYNAMICS
    Type: The 1987 Ground Vortex Workshop; p 61-90
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  • 86
    Publication Date: 2013-08-31
    Description: The interaction of the free stream velocity on the wall jet formed by the impingement of deflected engine thrust results in a rolled up vortex which exerts sizable forces on a short takeoff (STOL) airplane configuration. Some data suggest that the boundary layer under the free stream ahead of the configuration may be important in determining the extent of the travel of the wall jet into the oncoming stream. Here, early studies of the ground vortex are examined, and those results are compared to some later data obtained with moving a model over a fixed ground board. The effect of the ground vortex on the aerodynamic characteristics are discussed.
    Keywords: AERODYNAMICS
    Type: The 1987 Ground Vortex Workshop; p 1-38
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  • 87
    Publication Date: 2013-08-31
    Description: A real time thermal imaging system with temperature resolution better than + or - 1 C and spatial resolution of better than 0.5 mm was developed and applied to the analysis of melt surface thermal field distributions in both Czochralski and liquid encapsulated Czochralski (LEC) growth configurations. The melt is viewed in near normal incidence by a high resolution charge coupled device camera to which is attached a very narrow bandpass filter. The resulting image is digitized and processed using a pipelined pixel processor operating at an effective 40 million operations per second thus permitting real time high frequency spatial and temporal filtering of the high temperature scene. A multi-pixel averaging algorithm was developed which permits localized, low noise sensing of temperature variations at any location in the hot zone as a function of time. This signial is used to implement initial elements of a feedforward growth control scheme which is aimed at reducing disturbances to the melt caused by the batch nature of the growth process. The effect of magnetic melt stabilization on radial melt temperature distributions was measured using this technique. Problems associated with residual internal reflections and non-optimized path geometry are discussed.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, D.C. Noncontact Temperature Measurement; p 384-404
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  • 88
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2013-08-31
    Description: Design and operation of accurate millisecond and microsecond resolution optical pyrometers developed at the National Bureau of Standards during the last two decades are described. Results of tests are presented and estimates of uncertainties in temperature measurements are given. Calibration methods are discussed and examples of applications of fast pyrometry are given. Ongoing research in developing fast multiwavelength and spatial scanning pyrometers are summarized.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, D.C. Noncontact Temperature Measurement; p 214-232
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  • 89
    Publication Date: 2013-08-31
    Description: The gravity-free demixing behavior of aqueous polymer two-phase systems (APTPS) has been studied on Earth, and onboard KC-135 aircraft and the Space Shuttle. Results suggest a good correlation between the demixing behavior of isopycnic systems on Earth and the low g behavior of systems exhibiting phase density differences. The short term (20 s) behavior of APTPS onboard KC-135 aircraft has been shown to mimic their initial demixing behavior in space. It appears that the few minutes of low g provided by parabolic rocket flight will be sufficient to study all but the later stages of demixing of APTPS. We are therefore turning our attention toward the design and use of hardware for studying the demixing of APTPS onboard sounding rockets. This seminar will discuss the evolution of hardware and research from hand-held KC-135 and Shuttle hardware through to automated hardware designed for utilization of KC-135, sounding rocket, and Space Shuttle Mid-deck Locker flight opportunities.
    Keywords: MATERIALS PROCESSING
    Type: National Research Council of Canada, Workshop on Microgravity Experimentation in Aircraft and Rockets; p 63
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  • 90
    Publication Date: 2013-08-31
    Description: Over the past twelve years, members of the Aerospace Medical Research Unit of McGill University have carried out a wide variety of tests and experiments in the weightless condition created by parabolic flight. This paper discusses the pros and cons of that environment for the life scientist, and uses examples from the McGill program of the types of activities which can be carried out in a transport aircraft such as the NASA KC-135.
    Keywords: MATERIALS PROCESSING
    Type: National Research Council of Canada, Workshop on Microgravity Experimentation in Aircraft and Rockets; p 43-46
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  • 91
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2013-08-31
    Description: NASA's Zero-g aircraft, operated by the Johnson Space Center, provides the unique weightless or zero-g environment of space flight for hardware development and test and astronaut training purposes. The program, which began in 1959, uses a slightly modified Boeing KC-135A aircraft, flying a parabolic trajectory, to produce weightless periods of 20 to 25 seconds. The program has supported the Mercury, Gemini, Apollo, Skylab, Apollo-Soyuz and Shuttle programs as well as a number of unmanned space operations. Typical experiments for flight in the aircraft have included materials processing experiments, welding, fluid manipulation, cryogenics, propellant tankage, satellite deployment dynamics, planetary sciences research, crew training with weightless indoctrination, space suits, tethers, etc., and medical studies including vestibular research. The facility is available to microgravity research organizations on a cost-reimbursable basis, providing a large, hands-on test area for diagnostic and support equipment for the Principal Investigators and providing an iterative-type design approach to microgravity experiment development. The facility allows concepts to be proven and baseline experimentation to be accomplished relatively inexpensively prior to committing to the large expense of a space flight.
    Keywords: MATERIALS PROCESSING
    Type: National Research Council of Canada, Workshop on Microgravity Experimentation in Aircraft and Rockets; p 41
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  • 92
    Publication Date: 2013-08-31
    Description: The purpose is to develop an improved understanding of the electromagnetic, heat, and fluid flow phenomena in electromagnetically levitated metal droplets, both under earthbound and microgravity conditions. The main motivation for doing this work, together with the past accomplishments, and the plans for future research are discussed.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 2; p 715-735
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  • 93
    Publication Date: 2013-08-31
    Description: The objective is to determine the mechanism of gas-phase flame spread over solid fuel surfaces in the absence of any buoyancy or externally imposed gas-phase flow. Such understanding can be used to improve the fire safety aspects of space travel by providing information that will allow judicious selections of spacecraft materials and environments to be made. The planned experiment consists of measuring the flame spread rate over thermally thin and thermally thick fuels in a closed container in the low-gravity environment of the Space Shuttle. Measurements consist of flame spread rate and shape obtained from two views of the process as recorded on movie film and surface and gas-phase temperatures obtained from fine-wire thermocouples. The temperature measurements along with appropriate modeling provide information about the gas-to-solid heat flux. Environmental parameters to be varied are the oxygen concentration and pressure.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 2; p 643-674
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  • 94
    Publication Date: 2013-08-31
    Description: The Acoustic Containerless Experiment System (ACES) was flown on STS 41-B in February 1984 and was scheduled to be reflown in 1986. The primary experiment that was to be conducted with the ACES module was the containerless melting and processing of a fluoride glass sample. A second experiment that was to be conducted was the verification of a non-contact surface tension measurement technique using the molten glass sample. The ACES module consisted of a three-axis acoustic positioning module that was inside an electric furnace capable of heating the system above the melting temperature of the sample. The acoustic module is able to hold the sample with acoustic forces in the center of the chamber and, in addition, has the capability of applying a modulating force on the sample along one axis of the chamber so that the molten sample or liquid drop could be driven into one of its normal oscillation modes. The acoustic module could also be adjusted so that it could place a torque on the molten drop and cause the drop to rotate. In the ACES, a modulating frequency was applied to the drop and swept through a range of frequencies that would include the n = 2 mode. A maximum amplitude of the drop oscillation would indicate when resonance was reached and from that data the surface tension could be calculated. For large viscosity samples, a second technique for measuring surface tension was developed. The results of the ACES experiment and some of the problems encountered during the actual flight of the experiment will be discussed.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 2; p 557-567
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  • 95
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2013-08-31
    Description: The Lead-Zinc binary equilibrium system is currently being investigated. Ground based studies of this system were performed to examine the possibility of obtaining a couple which, after diffusion, could be examined continuously along the diffusion axis by quantitative metallography to determine the extent of diffusion. The specimens were analyzed by X-ray fluorescence in the scanning electron microscope to provide exact information on the chemical composition gradient. Two diffusion experiments were run simultaneously in the multipurpose furnace, each in its own isothermal cavity. Two flight samples, two flight backup samples, and two flight space samples were generated.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 1; p 511-521
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  • 96
    Publication Date: 2013-08-31
    Description: Although space research is still in an embryonic state, a combination of Earth based and space flight experiments are being coupled to yield a better understanding of the complex interaction of heat and fluid flow on the dynamics of crystal growth. Continued efforts on the ground as well as additional flight opportunities are needed to continue the drive to fully understand the advantages, both scientifically and economically, of microgravity crystal growth.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 1; p 391-407
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  • 97
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2013-08-31
    Description: A space shuttle experiment employing the General Purpose (Rocket) Furnace (GPF) in its isothermal mode of operation is manifested on MSL-3, circa 1989. The central aim of this experiment is to investigate the effect of reduced gravity levels on the segregation behavior in a slowly, and isothermally, cooled sample of a binary Pb-15 wt percent Sn alloy. This experiment would thus be able to simulate, in a small laboratory sample, about 20 mm dia 60 mm high and weighing about 150 grams, some aspects of the segregation phenomena occurring in large industrial ingots. Ground-based experiments conducted in the single-cavity simulator of the GPF, located at Marshall Space Flight Center (MSFC), in support of the microgravity experiment are described in detail. The results of the MSFC experiments are compared with other related experiments conducted at Case Western Reserve University (CWRU), wherein the isothermal constraints were relaxed.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 1; p 427-457
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  • 98
    Publication Date: 2013-08-31
    Description: Mercuric iodide is a material used for the fabrication of the sensing element in solid state X-ray and gamma ray detecting instruments. The operation of the devices is determined to a large degree by the density of structural defects in the single crystalline material used in the sensing element. Since there were strong indications that the quality of the material was degraded by the effects of gravity during the growth process, a research and engineering program was initiated to grow one or more crystals of mercuric iodide in the reduced gravity environment of space. A special furnace assembly was designed which could be accommodated in a Spacelab rack, and at the same time made it possible to use the same growth procedures and controls used when growing a crystal on the ground. The space crystal, after the flight, was subjected to the same evaluation methods used for earth-grown crystals, so that comparisons could be made.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 1; p 269-286
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  • 99
    Publication Date: 2013-08-31
    Description: Animal cells face a variety of environmental stresses in large scale bioreactors, including periodic variations in shear stress and dissolved oxygen concentration. Diagnostic techniques were developed for identifying the particular sources of environmental stresses for animal cells in a given bioreactor configuration. The mechanisms by which cells cope with such stresses was examined. The individual concentrations and synthesis rates of hundreds of intracellular proteins are affected by the extracellular environment (medium composition, dissolved oxygen concentration, ph, and level of surface shear stress). Techniques are currently being developed for quantifying the synthesis rates and concentrations of the intracellular proteins which are most sensitive to environmental stress. Previous research has demonstrated that a particular set of stress response proteins are synthesized by mammalian cells in response to temperature fluctuations, dissolved oxygen deprivation, and glucose deprivation. Recently, it was demonstrated that exposure of human kidney cells to high shear stress results in expression of a completely distinct set of intracellular proteins.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 1; p 235-248
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  • 100
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2013-08-31
    Description: Microgravity offers new ways of handling fluids, gases, and growing mammalian cells in efficient suspension cultures. In 1976 bioreactor engineers designed a system using a cylindrical reactor vessel in which the cells and medium are slowly mixed. The reaction chamber is interchangeable and can be used for several types of cell cultures. NASA has methodically developed unique suspension type cell and recovery apparatus culture systems for bioprocess technology experiments and production of biological products in microgravity. The first Space Bioreactor was designed for microprocessor control, no gaseous headspace, circulation and resupply of culture medium, and slow mixing in very low shear regimes. Various ground based bioreactors are being used to test reactor vessel design, on-line sensors, effects of shear, nutrient supply, and waste removal from continuous culture of human cells attached to microcarriers. The small Bioreactor is being constructed for flight experiments in the Shuttle Middeck to verify systems operation under microgravity conditions and to measure the efficiencies of mass transport, gas transfer, oxygen consumption and control of low shear stress on cells.
    Keywords: MATERIALS PROCESSING
    Type: NASA, Washington, Microgravity Science and Applications Flight Programs, January - March 1987, Selected Papers, Volume 1; p 195-215
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