1,606 research outputs found
Decompositions of some twisted Foulkes characters
We decompose the twisted Foulkes characters , or equivalently the plethysm , in the cases where has either two rows or two columns, or is a hook partition
Statistics of the Energy Dissipation Rate and Local Enstrophy in Turbulent Channel Flow
Using high-resolution direct numerical simulations, the height and Reynolds
number dependence of higher-order statistics of the energy dissipation rate and
local enstrophy are examined in incompressible, fully-developed turbulent
channel flow. The statistics are studied over a range of wall distances,
spanning the viscous sublayer to the channel flow centerline, for friction
Reynolds numbers and . The high resolution of
the simulations allows dissipation and enstrophy moments up to fourth order to
be calculated. These moments show a dependence on wall distance, and Reynolds
number effects are observed at the edge of the logarithmic layer. Conditional
analyses based on locations of intense rotation are also carried out in order
to determine the contribution of vortical structures to the dissipation and
enstrophy moments. Our analysis shows that, for the simulation at the larger
Reynolds number, small-scale fluctuations of both dissipation and enstrophy
become relatively constant for .Comment: Accepted by Physica
Nutritional properties and health aspects of pulses and their use in plant-based yogurt alternatives
Plant-based yogurt alternatives are increasing inmarket value,while dairy yogurt sales are stagnating or even declining. The plant-based yogurt alternatives market is currently dominated by products based on coconut or soy. Coconutbased products especially are often low in protein and high in saturated fat, while soy products raise consumer concerns regarding genetically modified soybeans, and soy allergies are common. Pulses are ideally suited as a base for plant-based yogurt alternatives due to their high protein content and beneficial amino acid composition. This review provides an overview of pulse nutrients, pro-nutritional and anti-nutritional compounds, how their composition can be altered by fermentation, and the chemistry behind pulse protein coagulation by acid or salt denaturation. An extensive market review on plant-based yogurt alternatives provides an overview of the current worldwide market situation. It shows that pulses are ideal base ingredients for yogurt alternatives due to their high protein content, amino acid composition, and gelling behavior when fermented with lactic acid bacteria. Additionally, fermentation can be used to reduce anti-nutrients such as α-galactosides and vicine or trypsin inhibitors, further increasing the nutritional value of pulse-based yogurt alternatives
Hot surface ignition dynamics in premixed hydrogen–air near the lean flammability limit
The dynamics of ignition of premixed hydrogen–air from a hot glow plug were investigated in a combined experimental and numerical study. Surface temperatures during heating and at ignition were obtained from 2-color pyrometry, gas temperatures were measured by high-speed Mach–Zehnder interferometry, and far-field effects were captured by high-speed schlieren imaging. Numerical simulations considered detailed chemical kinetics and differential diffusion effects. In addition to the known cyclic (puffing) combustion phenomenon, singular ignition events (single puff) were observed near the lean flammability limit. Detailed analysis of the results of our numerical simulations reveal the existence of multiple combustion transients within the thermal boundary layer following the initial ignition event and, at late times, sustained chemical reaction within a thermal plume above the glow plug. The results have significant implications for ignition from hot surfaces within near-flammability limit mixtures, at the edge of plumes resulting from accidental release of hydrogen, or within the containments of nuclear power plants during severe accidents
Dissipation-scale fluctuations in the inner region of turbulent channel flow
The statistics of intense energy dissipation events in wall-bounded shear flows are studied using highly resolved direct numerical simulations of turbulent channel flow at three different friction Reynolds numbers. Distributions of the energy dissipation rate and local dissipation scales are computed at various distances from the channel walls, with an emphasis on the behavior of the statistics in the near-wall region. The dependence of characteristic mean and local dissipation scales on wall distance is also examined over the full channel height. Systematic variations in these statistics are found close to the walls due to the anisotropy generated by mean shear and coherent vortical structures. Results near the channel centerline are consistent with those found in homogeneous isotropic turbulence
Highly efficient room temperature spin injection in a metal-insulator-semiconductor light emitting diode
We demonstrate highly efficient spin injection at low and room temperature in
an AlGaAs/GaAs semiconductor heterostructure from a CoFe/AlOx tunnel spin
injector. We use a double-step oxide deposition for the fabrication of a
pinhole-free AlOx tunnel barrier. The measurements of the circular polarization
of the electroluminescence in the Oblique Hanle Effect geometry reveal injected
spin polarizations of at least 24% at 80K and 12% at room temperature
Electrical Spin Injection in a Ferromagnetic / Tunnel Barrier/ Semiconductor Heterostructure
We demonstrate experimentally the electrical ballistic electron spin
injection from a ferromagnetic metal / tunnel barrier contact into a
semiconductor III-V heterostructure. We introduce the Oblique Hanle Effect
technique for reliable optical measurement of the degree of injected spin
polarization. In a CoFe / Al2O3 / GaAs / (Al,Ga)As heterostructure we observed
injected spin polarization in excess of 8 % at 80K.Comment: 5 pages, 4 figure
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