The shape of wake behind a wind turbine is normally assumed to have a hat shape for the models used in wind farm layout optimization purposes; however, it is know from experimental tests and numerical simulations that this is not a real assumption. In reality, the results of actual measurements and detailed numerical simulation show that the velocity in wake region has a S-shape profile. The pr...

The prevalence of colloid deposition at grain-to-grain contacts in two porous media (spherical glass beads and angular quartz sand, 710-850 microm) was examined using X-ray microtomography (XMT) under conditions where the colloid-grain surface interaction was solely attractive (lacking an energy barrier to deposition), and under fluid velocity conditions representative of engineered filtration ...

An attempt is made to summarize the different ways of modelling the anisotropy of a polycrystalline material. At the single crystal level, the formulation based on Schmid law or viscoplasticity shows clearly the microscopic anisotropy due to the hardening and the orientation changes. It is also shown how viscoplasticity leads to a unique slip system activity irrespectively of the rate sensitivi...

Context. Analysis of thermal dust emission spectra for dust mineralogy and physical grain properties depends on comparison spectra, which are either laboratory-measured infrared extinction spectra or calculated extinction cross sections based on certain grain models. Often, the agreement between these two kinds of spectra, if available, is not yet satisfactory because of the strong influence of...

The dynamic nanomechanical characteristics of Cu films with different grain boundaries under nanoindentation and scratch conditions were studied by molecular dynamics (MD) simulations. The type of grain boundary is the main factor in the control of the substrate atoms with respect to the size of dislocations since the existence of the grain boundary itself restricts the movement associated with...

The effects of rare earth addition and hot extrusion process on the grain refinement of magnesium alloy were studied. The as-cast Mg-6Al-1Zn (AZ61) alloy had the average grain size of ~ 64 µm and its microstructure consisted of α-Mg and Mg17Al12 phase. By partial substitution of Al with Gd to reach Mg-4.8Gd-1.2Al-1Zn alloy, it was observed that the Mg17Al12 phase disappeared and two new interme...

an internal ballistics model has been developed for performance prediction of a solid propellant rocket motor. inthis model a 1-d unsteady euler equation with source terms is considered. the flow is assumed as a non-reacting mixture of perfect gases with space and time varying thermo physical properties. the governing equations in the combustion chamber are solved numerically by using the stege...

BACKGROUND AND AIMS Microsporogenesis leading to monosulcate pollen grains has already been described for a wide range of monocot species. However, a detailed study of additional callose deposition after the completion of the cleavage walls has been neglected so far. The study of additional callose deposition in monosulcate pollen grain has gained importance since a correlation between addition...

Grain boundaries are extensively used as high-quality Josephson junctions in high-Tc superconductors. Their superconducting characteristics can generally be well described by conventional models of strongly coupled Josephson junctions. Here, we report on highly anomalous critical current vs. magnetic field dependencies of grain boundaries in YBa2Cu307-,. Direct imaging with scanning SQUID micro...