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  • 1
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    Overview of Active Flow Control at NASA Langley Research Center (1998)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: The paper summarizes Active Flow Control projects currently underway at the NASA Langley Research Center. Technology development is being pursued within a multidisciplinary, cooperative approach, involving the classical disciplines of fluid mechanics, structural mechanics, material science, acoustics, and stability and control theory. Complementing the companion papers in this session, the present paper will focus on projects that have the goal of extending the state-of-the-art in the measurement, prediction, and control of unsteady, nonlinear aerodynamics. Toward this goal, innovative actuators, micro and macro sensors, and control strategies are considered for high payoff flow control applications. The target payoffs are outlined within each section below. Validation of the approaches range from bench-top experiments to wind-tunnel experiments to flight tests. Obtaining correlations for future actuator and sensor designs are implicit in the discussion. The products of the demonstration projects and design tool development from the fundamental NASA R&D level technology will then be transferred to the Applied Research components within NASA, DOD, and US Industry. Keywords: active flow control, separation control, MEMS, review
    Keywords: Fluid Mechanics and Thermodynamics
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    NASA TECHNICAL REPORTS
  • 2
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    Multiple Mode Actuation of a Turbulent Jet (2001)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The effects of multiple mode periodic excitation on the evolution of a circular turbulent jet were studied experimentally. A short, wide-angle diffuser was attached to the jet exit. Streamwise and cross-stream excitations were introduced at the junction between the jet exit and the diffuser inlet on opposing sides of the jet. The introduction of high amplitude, periodic excitation in the streamwise direction enhances the mixing and promotes attachment of the jet shear-layer to the diffuser wall. Cross-stream excitation applied over a fraction of the jet circumference can deflect the jet away from the excitation slot. The two modes of excitation were combined using identical frequencies and varying the relative phase between the two actuators in search of an optimal response. It is shown that, for low and moderate periodic momentum input levels, the jet deflection angles depend strongly on the relative phase between the two actuators. Optimum performance is achieved when the phase difference is pi +/- pi/6. The lower effectiveness of the equal phase excitation is attributed to the generation of an azimuthally symmetric mode that does not produce the required non-axisymmetric vectoring. For high excitation levels, identical phase becomes more effective, while phase sensitivity decreases. An important finding was that with proper phase tuning, two unsteady actuators can be combined to obtain a non-linear response greater than the superposition of the individual effects.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Paper 2001-0735 , Aerospace Sciences; Jan 08, 2001 - Jan 11, 2001; Reno, NV; United States
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    NASA TECHNICAL REPORTS
  • 3
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    Multiple Mode Actuation of a Turbulent Jet (2001)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The effects of multiple mode periodic excitation on the evolution of a circular turbulent jet were studied experimentally. A short, wide-angle diffuser was attached to the jet exit. Streamwise and cross-stream excitations were introduced at the junction between the jet exit and the diffuser inlet on opposing sides of the jet. The introduction of high amplitude, periodic excitation in the streamwise direction enhances the mixing and promotes attachment of the jet shear-layer to the diffuser wall. Cross-stream excitation applied over a fraction of the jet circumference can deflect the jet away from the excitation slot. The two modes of excitation were combined using identical frequencies and varying the relative phase between the two actuators in search of an optimal response. It is shown that, for low and moderate periodic momentum input levels, the jet deflection angles depend strongly on the relative phase between the two actuators. Optimum performance is achieved when the phase difference is pi +/- pi/6. The lower effectiveness of the equal phase excitation is attributed to the generation of an azimuthally symmetric mode that does not produce the required non-axisymmetric vectoring. For high excitation levels, identical phase becomes more effective, while phase sensitivity decreases. An important finding was that with proper phase tuning, two unsteady actuators can be combined to obtain a non-linear response greater than the superposition of the individual effects.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Paper 2001-0735 , Aerospace Sciences; Jan 08, 2001 - Jan 11, 2001; Reno, NV; United States
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    NASA TECHNICAL REPORTS
  • 4
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    Sweeping Jet Optimization Studies (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Progress on experimental efforts to optimize sweeping jet actuators for active flow control (AFC) applications with large adverse pressure gradients is reported. Three sweeping jet actuator configurations, with the same orifice size but dierent internal geometries, were installed on the flap shoulder of an unswept, NACA 0015 semi-span wing to investigate how the output produced by a sweeping jet interacts with the separated flow and the mechanisms by which the flow separation is controlled. For this experiment, the flow separation was generated by deflecting the wing's 30% chord trailing edge flap to produce an adverse pressure gradient. Steady and unsteady pressure data, Particle Image Velocimetry data, and force and moment data were acquired to assess the performance of the three actuator configurations. The actuator with the largest jet deflection angle, at the pressure ratios investigated, was the most efficient at controlling flow separation on the flap of the model. Oil flow visualization studies revealed that the flow field controlled by the sweeping jets was more three-dimensional than expected. The results presented also show that the actuator spacing was appropriate for the pressure ratios examined.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NF1676L-22842 , 2016 AIAA Aviation Technology, Integration, and Operations Conference; Jun 13, 2016 - Jun 17, 2016; Washington, DC; United States
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    NASA TECHNICAL REPORTS
  • 5
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    Active Flow Control Using Sweeping Jet Actuators on a Semi-Span Wing Model (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Wind tunnel experiments were performed using active flow control on an unswept semispan wing model with a 30% chord trailing edge flap to aid in the selection of actuators for a planned high Reynolds number experiment. Two sweeping jet actuator sizes were investigated to determine the influence of actuator size on the active flow control system efficiency. Sweeping jet actuators with orifice sizes of 1 mm x 2 mm and 2 mm x 4 mm were selected because of the differences in actuator jet sweep angle. The parameters that were varied include actuator momentum, freestream velocity, and trailing edge flap deflection angle. Steady and unsteady pressure data, Particle Image Velocimetry data, and force and moment data were acquired to assess the performance of the two actuators. In addition to the wind tunnel experiments, benchtop studies of the actuators were performed to characterize the jets produced by each actuator. Benchtop investigations of the smaller actuator reveal that the jet exiting the actuator has a reduced sweep angle compared to published data for larger versions of this type of actuator. The larger actuator produces an oscillating jet that attaches to the external diuser walls at low supply pressures and produces the expected sweep angles. The AFC results using the smaller actuators show that while the actuators can control flow separation, the selected spacing of 3.3 cm may be too large due to the reduced sweep angle. In comparison, the spacing for the larger actuators, 6.6 cm, appears to be optimal for the Mach numbers investigated. Particle Image Velocimetry results are presented and show how the wall jets produced by the actuators cause the flow to attach to the flap surface.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NF1676L-21616 , AIAA SciTech Conference; Jan 04, 2016 - Jan 08, 2016; San Diego, CA; United States
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    NASA TECHNICAL REPORTS
  • 6
    Electronic Resource
    Electronic Resource
    Isolation and cultivation of blastocyst-derived stem cell lines from american mink (Mustela vison) (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 33 (1992), S. 418-431 
    Details
    ISSN: 1040-452X
    Keywords: Embryonic stem cells ; Cell differentiation ; Pluripotency ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Ten embryonic stem (ES) cell lines from mink blastocysts were isolated and characterized. All the lines had a normal diploid karyotype; of the ten lines studied, five had the XX and five had the XY constitution. Testing of the pluripotency of the ES-like cells demonstrated that (1) among four lines of genotype XX, an X was late-replicating in three; both Xs were active in about one-third of cells of line MES8, and analysis of glucose-6-phosphate dehydrogenase revealed no dosage compensation for the X-linked gene; (2) when cultured in suspension, the majority of lines were capable of forming “simple” embryoid bodies (EB), and two only showed the capacity for forming “cystic” multilayer EBs. However, formation of ectoderm or foci of yolk sac hematopoiesis, a feature of mouse ES ceils, was not observed in the “cystic” EB; (3) when cultured as a monolayer without feeder, the ES cells differentiated into either vimentin-positive fibroblast-like cells or cytokeratin-positive epithelial-like cells (less frequently); neural cells appeared in two lines; (4) when injected into athymic mice, only one of the four tested lines gave rise to tumors. These were fibrosarcomas composed of fibrobalst-like cells, with an admixture of smooth muscular elements and stray islets of epithelial tissue; (5) when the ES cells of line MES1 were injected into 102 blastocyst cavities and subsequently transplanted into foster mathers, we obtained 30 offspring. Analysis of the biochemical markers and coat color did not demonstrate the presence of chimaeras among offspring. Thus the cell lines derived from mink blastocysts are true ES cells. However, their pluripotential capacities are restricted. © 1992 Wiley-Liss, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080330408
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  • 7
    Electronic Resource
    Electronic Resource
    Isolation, composition, and biological activity of sugar chains of porcine oocyte zona pellucida 55K glycoproteins (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 30 (1991), S. 126-134 
    Details
    ISSN: 1040-452X
    Keywords: Egg envelope ; Peptide N-glycosidase F digestion ; Oligosaccharides ; Sulfated polylactosamines ; Sperm-zona binding ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: ZP3, a preparation of the 55K families of porcine oocyte zona pellucida, possesses carbohydrate-dependent ligand activity for boar sperm. The aim of the present study was to analyze ZP3 N- and O-linked oligosaccharides with respect to size distribution, composition, and role in sperm-zona recognition events. Digestion of denatured ZP3 with peptide N-glycosidase F (PNGaseF) released the majority of N-glycans which fractionated on Sephadex G-75 resin as a polydisperse population with apparent molecular masses ranging from 1,900-8,200 Da. The higher molecular weight N-glycans were characterized by the presence of strongly anionic sulfated/sialylated polylactosamine structures. Alkaline-borohydride treatment of the PNGaseF-digested core proteins liberated O-glycans as a heterogeneous population of oligosaccharide alcohols, which were fractionated on a Sephadex G-50 column. Compositional analyses indicated sulfated polylactosamine units associated with the higher molecular weight O-glycans. Preincubation of boar sperm with ZP3 or purified O-glycans, but not N-glycans, inhibited subsequent attachment to zona-encased oocytes. Purified O-glycans were, however, 2 to 3 orders of magnitude less effective than ZP3 as competitive ligands. The results document the extreme heterogeneity of the ZP3 carbohydrate moiety, in large part attributable to a board spectrum of variably sized N- and O-linked sulfated polylactosamines. Ligand competition bioassays suggest that O-glycans mediate, at least in part, the sperm adhesive properties of ZP3 and strongly imply that high-affinity interaction of ZP3 sugar chains with complementary sperm receptors is dependent upon their covalent association with core proteins.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080300209
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  • 8
    Electronic Resource
    Electronic Resource
    Porcine oocyte zona pellucida Mr 55,000 glycoproteins: Identification of O-glycosylated domains (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 33 (1992), S. 182-188 
    Details
    ISSN: 1040-452X
    Keywords: Glycopeptides ; O-linked oligosaccharides ; Jacalin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The distribution of O-linked oligosaccharides on the Mr 55,000 glycoproteins, ZP3α and ZP3, of the porcine oocyte zona pellucida was examined. Purified preparations of endo-β-galactosidase digested ZP3α and ZP3β were reduced and carboxamidomethylated and digested with trypsin. When the trypsin digests were mapped by HPLC, each glycoprotein yielded only one N-acetylgalactosamine containing glycopeptide. Purification of the O-glycopeptides was achieved by a two-step protocol. Tryptic digests were applied to jacalin-agarose and specifically-bound O-glycopeptides (αOGP and βOGP) were eluted with buffer containing 50 mM α-methylgalactoside as the haptenic sugar. Further purification of each O-glycopeptide was accomplished by reverse phase HPLC. Purified O-glycopeptides were characterized with respect to amino acid and carbohydrate compositions and sequenced by automated Edman degradation; αOGP was a 41-residue glycopeptide with three O-linked sugar chains. Sequence comparisons revealed a 75% identity between αOGP and a corresponding segment of rabbit rec55 zona protein; OGP was a 25-residue glycopeptide characterized by the presence of one N-linked and five O-linked sugar chains and a trypsin-resistant internal arginine residue. Sequence alignments revealed an 80% or greater identity between βOGP and internal peptides of mouse, hamster and human ZP3 zona proteins. These studies demonstrate that in the case of ZP3α and ZP3β, the pig homologues of rabbit rec55 and mouse ZP3, respectively, O-linked oligosaccharides are confined within delimited domains rather than widely dispersed on the polypeptide backbone. Such clustering of O-linked oligosaccharides may represent an essential determinant of the structure and biological activity of zona proteins. © 1992 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080330210
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  • 9
    Electronic Resource
    Electronic Resource
    Porcine zona pellucida ZP3α glycoprotein mediates binding of the biotin-labeled Mr 55,000 family (ZP3) to boar sperm membrane vesicles (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 36 (1993), S. 382-389 
    Details
    ISSN: 1040-452X
    Keywords: Pig spermatozoa ; Sperm adhesive protein ; Competitive ligand binding assay ; Polylactosamines ; Fucoidin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The two Mr 55,000 glycoproteins, ZP3α and ZP3b̃, of porcine zona pellucida copurify as a preparation designated ZP3. Gamete binding assays have implicated ZP3α, but not ZP3b̃, as participating in sperm-zona recognition events. We now report that boar sperm contain membrane-associated binding sites with specificity for ZP3α. Biotin-labeled (b-) preparations of ZP3 bind to intact boar sperm in a saturable manner, with localization on the anterior head region. Membrane vesicles obtained from capacitated sperm by nitrogen cavitation retain b-ZP3 binding sites as determined by an enzyme-linked method employing alkaline phosphatase-conjugated strepavidin. In competitive binding assays using b-ZP3 (0.1μg/ml) as probe, heat-solubilized zonae and ZP3 were effective competitors, whereas the nonzona molecules fetuin and fucoidin were not. Digestion of ZP3 with endo-b̃-galactosidase, an enzyme that trims polylactosamines, enhanced its affinity for membrane receptors. In contrast treatments such as chemical deglycosylation, pronase digestion, or disruption of disulfide bonds abolished the ligand activity of ZP3. Finally, purified ZP3α was an at least 100-fold better antagonist than purified ZP3b̃. The results demonstrate that binding of b-ZP3 to isolated boar sperm membranes is mediated by sperm receptors with specificity for the ZP3α macromolecular component and reveal a complex contribution of both carbohydrate and protein moieties toward the ligand activity of this sperm adhesive zona molecule. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080360315
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  • 10
    Electronic Resource
    Electronic Resource
    Estivation in Protopterus (1986)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 190 (1986), S. 237-248 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Estivation in Protopterus is an episodic event characterized by elaboration of a cocoon as ambient water is withdrawn, a state of torpor, and distinctive cardiorespiratory and metabolic changes. Among the more striking of these features is a decrease in oxygen consumption, a complete reliance on air breathing to satisfy metabolic need, a slowing of the heart rate, and a drop in blood pressure. The initiating mechanism for these dramatic changes is not known. As yet, specific “estivating factors” have not been identified. However, the pattern of decrease in oxygen uptake during estivation and starvation are quite similar, suggesting that a common factor may be involved in both. Attempts to implicate suppression of thyroid function in the onset of estivation have been unconvincing. Although initiating mechanisms for estivation in Protopterus remain uncertain, once estivation sets in a variety of adaptive changes occur that enable the estivating lungfish to survive for months to years without ingesting food or water. Among these are oliguria and a shift in metabolic pathways. Although estivation in Protopterus has been characterized with respect to cardiorespiratory and metabolic parameters, no attempt is made to extrapolate from the biologic processes in Protopterus to other lepidosirenid lungfish or to other genera.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051900416
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