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  • 1
    Electronic Resource
    Electronic Resource
    Adaptive Wind Tunnels (1988)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 20 (1988), S. 17-32 
    Details
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.fl.20.010188.000313
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Dipolarization in the inner magnetosphere during a geomagnetic storm on 7 October 2015 (2016)
    Wiley
    Details
    Publication Date: 2016-09-06
    Description: A dipolarization event was observed by the Magnetospheric Multiscale (MMS) spacecraft at L =3.8 and 19.8 magnetic local time (MLT) starting at  ∼ 23:42:36 UT on 7 October 2015. The magnetic and electric fields showed initially coherent variations between the spacecraft. The sunward convection turned tailward after the dipolarization. The observation is interpreted in terms of the pressure balance or the momentum equation. This was followed by a region traversed where the fields were irregular. The scale length was of the order of the ion gyroradius, suggesting the kinetic nature of the fluctuations. Combination of the multi-instrument, multi-spacecraft data reveals a more detailed picture of the dipolarization event in the inner magnetosphere. Conjunction ionosphere-plasmasphere observations from DMSP, two-dimensional GPS TEC, the Millstone Hill mid-latitude incoherent scatter radar, and AMPERE measurements imply that MMS observations are located on the poleward edge of the ionospheric trough where Region 2 field aligned currents flow.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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    PAPER CURRENT
  • 3
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    Adaptive Wind Tunnels (1988)
    Annual Reviews
    Details
    Publication Date: 1988-01-01
    Print ISSN: 0066-4189
    Electronic ISSN: 1545-4479
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Annual Reviews
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    PAPER CURRENT
  • 4
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    Streamlining algorithms for complete adaptation (1990)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: For purposes of the adaptive-wall algorithms to be described, the modern era is considered to have begun with the simultaneous, independent recognition of the concept of matching an experimental inner flow across an interface to a computed outer flow by Chevallier, Ferri, Goodyer, Lissaman, Rubbert, and Sears. Fundamental investigations of the adaptive-wall matching concept by means of numerical simulations and theoretical considerations are described. An overview of the development and operation of 2D adaptive-wall facilities from about 1970 until the present is given, followed by similar material for 3D adaptive-wall facilities from approximately 1978 until the present. A general formulation of adaptation strategy is presented, with a theoretical basis for adaptation followed by 2D flexible, impermeable-wall applications; 2D ventilated-wall applications; 3D flexible, impermeable-wall applications; and 3D ventilated-wall applications. Representative experimental and 3D results are given, with 2D, followed by a discussion of limitations and open questions.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: AGARD, Fluid Dynamics Panel Working Group 12 on Adaptive Wind Tunnel Walls: Technology and Applications; p 21-41
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    Limits of adaptation, residual interferences (1990)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: Methods of determining linear residual wall interference appear to be well established theoretically; however they need to be validated, for example by comparative studies of test data on the same model in different adaptive-wall wind tunnels as well as in passive, ventilated-wall tunnels. The GARTEur CAST 7 and the CAST 10/DOA 2 investigations are excellent examples of such comparative studies. Results to date in both one-variable and two-variable methods for nonlinear wall interference indicate that a great deal more research and validation are required. The status in 2D flow is advanced over that in 3D flow as is the case generally with adaptive-wall development. Nevertheless, it is now well established that for transonic testing with extensive supercritical flow present, significant wall interference is likely to exist in conventional ventilated test sections. Consequently, residual correction procedures require further development hand-in-hand with further adaptive-wall development.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: AGARD, Fluid Dynamics Panel Working Group 12 on Adaptive Wind Tunnel Walls: Technology and Applications; p 66-90
    Format: text
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  • 6
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    Enhancement of peptide bond formation by polyribonucleotides on clay surfaces in fluctuating environments (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The selective effects of polyribonucleotides on the formation of glycine peptide bonds in glycine on clay surfaces are investigated as a model for a template mechanism for the effects of polynucleotides on peptide bond formation. Free oligoglycine yields were determined for the cycling reaction of glycine in the presence and absence of clay and polyribonucleotides or polydeoxyribonucleotides. The polyribonucleotides are observed to lead to increases of up to fourfold increases in oligoglycine formed, with greater enhancements for poly-G nucleotides than for poly-A, poly-U and poly-C, indicating a codonic bias. Polydeoxyribonucleotides are found to provide no enhancement in peptide formation rates, and yields were also greatly reduced in the absence of clay. A mechanism for peptide synthesis is proposed which involves the activation of glycine on the clay surface, followed by the formation of esters between glycine and the 2-prime OH groups of the polyribonucleotide and peptide bonds between adjacent amino acyl esters. It is pointed out that if this mechanism is correct, it may provide a basis for a direct template translation process, which would produce a singlet genetic code.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Journal of Molecular Evolution; 17; Mar. 198
    Format: text
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    NASA TECHNICAL REPORTS
  • 7
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    Catalysis of peptide bond formation by histidyl-histidine in a fluctuating clay environment (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The condensation of glycine to form oligoglycines during wet-dry fluctuations on clay surfaces was enhanced up to threefold or greater by small amounts of histidyl-histidine. In addition, higher relative yields of the longer oligomers were produced. Other specific dipeptides tested gave no enhancement, and imidazole, histidine, and N-acetylhistidine gave only slight enhancements. Histidyl-histidine apparently acts as a true catalyst (in the sense of repeatedly catalyzing the reaction), since up to 52 nmol of additional glycine were incorporated into oligoglycine for each nmol of catalyst added. This is the first known instance of a peptide or similar molecule demonstrating a catalytic turnover number greater than unity in a prebiotic oligomer synthesis reaction, and suggests that histidyl-histidine is a model for a primitive prebiotic proto-enzyme. Catalysis of peptide bond synthesis by a molecule which is itself a peptide implies that related systems may be capable of exhibiting autocatalytic growth.
    Keywords: CHEMISTRY AND MATERIALS (GENERAL)
    Type: Journal of Molecular Evolution; 16; Dec. 198
    Format: text
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  • 8
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    Experiments with a self-correcting wind tunnel (1976)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The feasibility of controlling the flow actively through the walls of a transonic, porous wall wind tunnel in order to minimize wall interference effects on a test model is demonstrated. The method is based upon measuring the components of the disturbance velocity at discrete points along an imaginary surface in the flow field within the tunnel. A mathematical formulation of the flow field exterior to the surface including the boundary condition for unconfined flow, i.e., that all disturbance vanish at infinite, is used to determine if these measured velocity components are consistent with that boundary condition. If they are not, the theory provides a better approximation to the velocity component for unconfined flow, and the flow through the tunnel walls is readjusted iteratively until the measured quantities are consistent with unconfined flow. A brief review of theoretical methods is followed by a description of the Calspan self correcting wind tunnel design and operation, calibration with and without active wall control. Typical results obtained by approximating a conventional porous wall wind tunnel for an 0012 airfoil show that active wall control largely reproduces the correct shock wave position, eliminates wall interference of lift and drag, and reduces the interference effects on pitching moment to 10%.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: AGARD Wind Tunnel Design and Testing Tech.; 13 p
    Format: text
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  • 9
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    Application of the adaptive-wall concept to three-dimensional low-speed wind tunnels (1976)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Three methods for evaluating the functional relationships required to obtain interference-free flows about a model in a wind tunnel have been developed. The first, the original multipole expansion (MPE) procedure, is based on a series of point singularities which satisfy the governing Prandtl-Glauert equation. The second, the modified MPE, provides an improved representation of finite-span wings and thereby extends the range of validity of the original MPE to larger ratios of span-to-control-surface-width. The third method is more general and is based on source distributions over the control surface. Several numerical examples are presented to help establish the range of validity of these methods. An accuracy-assessment procedure, which combines the original MPE procedure with classical wall-correction theory, has been developed to estimate the degree of interference at the model if the functional relationships are not satisfied exactly. Several numerical examples are presented for representative wings and bodies.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: NASA-CR-137917 , RK-5717-A-1
    Format: application/pdf
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  • 10
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    Interference-free wind-tunnel flows by adaptive-wall technology (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The adaptive-wall or self-correcting wind tunnel has been proposed for such regimes as transonic and V/STOL where wall effects are large and cannot be corrected for. The power and generality of the concept are pointed out. In a two-dimensional transonic embodiment in the Calspan One-Foot Tunnel, the scheme has been shown to work at lower transonic Mach numbers. Several practical problems are cited, including instrumentation, the nature of the wall modification, and convergence of the iterative procedure. Moreover, questions of shock-wave neutralization at the wall and probable configuration of three-dimensional embodiments are discussed.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: ICAS PAPER 76-02 , Congress; Oct 03, 1976 - Oct 08, 1976; Ottawa; Canada
    Format: text
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