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1

Electronic Resource

Compressible spreading rates of supersonic coaxial jets (1990)

Schadow, K. C. ; Gutmark, E. ; Wilson, K. J.

Springer

Experiments in fluids 10 (1990), S. 161-167

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ISSN: 1432-1114

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract The compressible spreading rates of two supersonic coaxial jets were studied experimentally. The center jet had a fully-expanded Mach number of 3, and the outer jet of M = 1.8. The geometries of the center jet were circular and rectangular with two configurations, both with a 3∶1 aspect-ratio. The convective Mach numbers were varied in the range between 0.25 〈 M c〈 2.25. This was accomplished by varying the density ratio between the center jet and the coaxial jet, as well as the velocity ratio. The experimental compressible spreading rate was determined using Schlieren photography and total-pressure measurements. The spreading rate of the center circular jet decreased with increasing convective Mach number until it reached a constant value of 0.2 to 0.3 of the incompressible spreading rate for M c〉1.4. The rectangular jets exhibited a similar drop, at the same range of M c, but their spreading rate was higher relative to the circular jet in the entire convective Mach number range.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00215025

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2

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Effect of convective Mach number on mixing of coaxial circular and rectangular jets (1991)

Gutmark, E. ; Schadow, K. C. ; Wilson, K. J.

New York, NY : American Institute of Physics (AIP)

Physics of Fluids 3 (1991), S. 29-36

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ISSN: 1089-7666

Source: AIP Digital Archive

Topics: Physics

Notes: Rectangular supersonic free and coaxial jets were used to enhance mixing relative to a circular jet in a convective Mach number range of 0.5 to 2.2. The different convective Mach numbers were obtained by changing the central jet gas composition, the temperatures of the inner and outer flows, and the velocity of the coaxial flow. The experimental techniques used were schlieren photography, total pressure, and gas-sampling measurements. For all test conditions the rectangular jets showed substantial improved mixing relative to a circular jet. The free jets showed high mixing in the circumferential region of the jet while the coaxial jet had a high mixing rate inside the central jet.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.857860

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3

Electronic Resource

Near-field pressure radiation and flow characteristics in low supersonic circular and elliptic jets (1988)

Gutmark, E. ; Schadow, K. C. ; Wilson, K. J. ; [et al.]

[S.l.] : American Institute of Physics (AIP)

Physics of Fluids 31 (1988), S. 2524-2532

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ISSN: 1089-7666

Source: AIP Digital Archive

Topics: Physics

Notes: The near-field pressure fluctuations of circular and elliptic underexpanded supersonic jets were studied experimentally. Unlike the case of low subsonic jets, the pressure fluctuation characteristics at the minor axis plane of the elliptic jet were very different from those of the major axis plane. The amplitude of the pressure fluctuations at the minor axis was more than an order of magnitude higher than at the other plane. This section of the jet was also characterized by a larger spreading rate and higher amplification rate of the velocity fluctuations. The circular jet was similar to the major axis plane of the elliptic jet. The spectra of the near-field pressure fluctuations of both jets exhibited the highest peak at a frequency corresponding to the jets' preferred mode frequency. The spectral peak related to the screech tone was much stronger at the minor axis plane and had the same frequency as at the other plane. The amplitude of the dominant pressure fluctuation frequencies was mapped in the entire near field, and each one was found to be dominant in a different region.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.867011

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4

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Membrane fluidity changes in embryogenic and non-embryogenic cultures of Asclepias and Daucus in response to auxin removal (1991)

Wilson, K. J. ; Stillwell, W. ; Maxam, T. ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Physiologia plantarum 82 (1991), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Significant differences in membrane fluidities, expressed as fluorescence anisotropies, are demonstrated between embryogenic (E) and non-embryogenic (NE) cell lines when cells in suspension culture are removed from auxin. Cells of an E and NE cell line of Asclepias tuberosa were grown for 21 days either with or without 2, 4-dichlorophenoxy acetic acid (2,4-D), cultures were sampled at various intervals and protoplast membrane (hydrophobic interiors) was labeled with 1, 6 diphenyl-1, 3, 5-hexatriene (DPH). No differences between cultures with and without 2,4-D were detected in the NE line. In contrast the E line rapidly developed differences in membrane fluidity over time. Such clear differences in the responses of E and NE lines in membrane fluidity indicated that this parameter could be a good predictor and marker for embryogenesis. Eight suspension cell lines of Asclepias and 2 of Daucus carota were tested. After 2 days on medium without auxin, every E cell line exhibited a positive change in anisotropy and became embryogenic, whereas NE cell lines exhibited much lower positive changes or even negative changes in anisotropy and never underwent embryogenesis. Such changes have been consistent in all cell lines tested and represent a marker for embryogenicity in suspension cell lines before morphological change becomes apparent after removal from auxin. Basic molecular membrane changes in embryogenesis are likely to be common among different culture systems and understanding them could be a major step in removing barriers to regenerating plants from cultured material.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1399-3054.1991.tb02957.x

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5

Electronic Resource

Selective control of flow coherence in triangular jets (2004)

Schadow, K. C. ; Gutmark, E. ; Parr, D. M. ; [et al.]

Springer

Experiments in fluids 6 (2004), S. 129-135

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ISSN: 1432-1114

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract The triangular jet was investigated for use as a passive device to enhance fine-scale mixing and to reduce the coherence of large-scale structures in the flow. The suppression of the structures is vital to the enhancement of molecular mixing, which is important for efficient chemical reactions including combustion. The sharp corners in the jet injector introduced high instability modes into the flow via the non-symmetric mean velocity and pressure distribution around the nozzle. Both aerodynamic and hydrodynamic flows showed the difference between the flow at the corner (vertex) and at the flat side. While highly coherent structures could be generated at the flat side, the corner flow was dominated by highly turbulent small-scale eddies. The flow characteristics were tested using hotwire anemometry for mean flow and turbulence analysis, and flow visualization in air and water.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00196464

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6

Electronic Resource

Noncircular jets in combustion systems (1989)

Gutmark, E. ; Schadow, K. C. ; Parr, T. P. ; [et al.]

Springer

Experiments in fluids 7 (1989), S. 248-258

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ISSN: 1432-1114

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract Combustion dynamics of burners with corners were studied using Planar Laser Induced Fluorescence (PLIF) imaging. The effect of sharp corners on the air flow dynamics, shown earlier in cold flow tests, was also found in the reacting flow of a flame. The sharp corners interrupted the coherent structures generated in an axisymmetric shear flow. The combustion at the flat sections of the flame occurred in periodic, coherent large scale structures but was continuous and homogeneous in the vertices sections. The azimuthal structure of the noncircular flame changed in a pattern similar to that found in nonreacting flows. Combined regions of small- and large-scale mixing in the same flow, a unique feature of burners having sharp corners, is beneficial for combustion applications.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00198004

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7

Electronic Resource

Immunocytochemical identification of laticifers (1984)

Wilson, K. J. ; Petersen, B. H. ; Biesboer, D. D.

Springer

Protoplasma 122 (1984), S. 86-90

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ISSN: 1615-6102

Keywords: Immunocytochemistry ; Non-articulated laticifers ; Articulated laticifers ; Asclepiadaceae

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary sensitive immunocytochemical method for the identification of laticifers has been developed. Frozen sections of various laticifer-bearing plant material, mounted on slides, were first flooded with the IgG fraction of rabbit anti-latex antiserum, prepared using whole latex ofAsclepias syriaca, then flooded with fluorescein-conjugated IgG fraction goat anti-rabbit IgG to visualize laticifers. Positive fluorescence was observed for laticifers in shoots and embryos ofA. syriaca andStapelia bella and embryos ofA. tuberosa. Laticifers did not fluoresce in shoots ofA. tuberosa andEuphorbia tirucalli, in embryos ofE. marginata, or in petioles ofMusa paradisiaca andCichorium intybus. Controls prepared with uninjected rabbit serum were negative (no fluorescence).

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01279440

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8

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A rapid model for estimating the depletion in river flows due to groundwater abstraction (2012)

Hulme, P. J. ; Jackson, C. R. ; Atkins, J. K. ; [et al.]

In: Geological Society Special Publication 364: 289-302.

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Publication Date: 2012-04-23

Description: The Environment Agency of England and Wales uses its calibrated regional models to estimate the reduction in river flows resulting from proposed groundwater abstractions. Where there is no regional model, analytical equations can produce quick initial estimates of river flow depletion. However, users often want more confidence in their estimates by representing more faithfully their understanding of the real river–aquifer system. This paper shows that, when using a numerical model designed to predict river flow depletion, it is important to include adjacent catchments and intermittent streams and less important to include river elevations and variations in transmissivity with groundwater head. Recharge does not usually need to be included unless part of the river becomes disconnected or dry. Therefore, for rivers where stream length is constant and transmissivity variations are small, it is valid to use a ‘no-recharge’ depletion model, which can be built quickly (within a month). A case study on the River Leith in NW England illustrates the use of such a model to assess the ecological impact of two groundwater abstraction licences under the European Union Habitats Directive.

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