312 research outputs found
Soot formation in a turbulent swirling flow
The qualitative understanding of soot formation in simple models of gas turbine primary-zone combustors is summarized. Soot formation in flame radiation and air pollution was investigated. Results are presented, namely: (1) if the fuel is premixed with air in approximately stoichiometric proportions, the sequence of states that a fluid element undergoes as it burns is quite different from the sequence when liquid or vapor fuel is injected into an air-flow; (2) swirling flows, as are typical or swirl-can combustors, when burning, can amplify small aerodynamic disturbances upstream of the swirl vanes; and (3) different fuels form significantly different amounts of soot. Each of these effects makes major changes in the amount of soot formed in a given combustor
Laboratory measurements in a turbulent, swirling flow
Measurements of soot inside a flame-tube burner using a special water-flushed probe are discussed. The soot is measured at a series of points at each burner, and upon occasion gaseous constitutents NO, CO, hydrocarbons, etc., were also measured. Four geometries of flame-tube burners were studied, as well as a variety of different fuels. The role of upstream geometry on the downstream pollutant formation was studied. It was found that the amount of soot formed in particularly sensitive to how aerodynamically clean the configuration of the burner is upstream of the injector swirl vanes. The effect of pressure on soot formation was also studied. It was found that beyond a certain Reynolds number, the peak amount of soot formed in the burner is constant
Euler-Lagrange relationship for random dispersive waves Scientific report
Euler-Lagrange relationship for random dispersive wave
Euler-Lagrange relationship for random dispersive waves
Euler-Lagrange relationship for random dispersive wave
A subsonic D-region probe-theory and instrumentation Scientific report no. 247
D-layer, subsonic, ion and electron probe operational mobility theory and instrumentation descriptio
Two-Dimensional Magnetic Resonance Tomographic Microscopy using Ferromagnetic Probes
We introduce the concept of computerized tomographic microscopy in magnetic
resonance imaging using the magnetic fields and field gradients from a
ferromagnetic probe. We investigate a configuration where a two-dimensional
sample is under the influence of a large static polarizing field, a small
perpendicular radio-frequency field, and a magnetic field from a ferromagnetic
sphere. We demonstrate that, despite the non-uniform and non-linear nature of
the fields from a microscopic magnetic sphere, the concepts of computerized
tomography can be applied to obtain proper image reconstruction from the
original spectral data by sequentially varying the relative sample-sphere
angular orientation. The analysis shows that the recent proposal for atomic
resolution magnetic resonance imaging of discrete periodic crystal lattice
planes using ferromagnetic probes can also be extended to two-dimensional
imaging of non-crystalline samples with resolution ranging from micrometer to
Angstrom scales.Comment: 9 pages, 11 figure
Magnetic field independence of the spin gap in YBa_2Cu_3O_{7-delta}
We report, for magnetic fields of 0, 8.8, and 14.8 Tesla, measurements of the
temperature dependent ^{63}Cu NMR spin lattice relaxation rate for near
optimally doped YBa_2Cu_3O_{7-delta}, near and above T_c. In sharp contrast
with previous work we find no magnetic field dependence. We discuss
experimental issues arising in measurements of this required precision, and
implications of the experiment regarding issues including the spin or pseudo
gap.Comment: 4 pages, 3 figures, as accepted for publication in Physical Review
Letter
Nuclear Magnetic Resonance Imaging with 90 nm Resolution
Magnetic resonance imaging, based on the manipulation and detection of
nuclear spins, is a powerful imaging technique that typically operates on the
scale of millimeters to microns. Using magnetic resonance force microscopy, we
have demonstrated that magnetic resonance imaging of nuclear spins can be
extended to a spatial resolution better than 100 nm. The two-dimensional
imaging of 19F nuclei was done on a patterned CaF2 test object, and was enabled
by a detection sensitivity of roughly 1200 nuclear spins. To achieve this
sensitivity, we developed high-moment magnetic tips that produced field
gradients up to 1.4x10^6 T/m, and implemented a measurement protocol based on
force-gradient detection of naturally occurring spin fluctuations. The
resulting detection volume of less than 650 zl represents 60,000x smaller
volume than previous NMR microscopy and demonstrates the feasibility of pushing
magnetic resonance imaging into the nanoscale regime.Comment: 24 pages, 5 figure
When learning becomes a fetish: the pledge, turn and prestige of magic tricks
It is our contention that the process of higher education could be read as a commodity and in both Marxian and Freudian assumptions, a fetish. Instrumental in this discussion are; Marx’s theorising of the commodity fetish (1867) that deceives by conflating the distinction between use and exchange value, and Freud’s (1927) re-visiting of his theory of fetishism, where he considers the fetish in the context of dealing with separation and loss in everyday life.
This paper highlights how the consequence of fetishised behaviour has led to violent outcomes, such as the policy decision to introduce a ‘Teaching Excellence Framework’ (TEF). We argue that the TEF may bring about the death of learning in HE and diminish the role of academic staff. Nevertheless, influenced by Winnicott, Cixous and Biesta, we offer a more hopeful ‘Teaching that is Good Enough Framework’
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