23,710 research outputs found
Dynamical density functional theory for the evaporation of droplets of nanoparticle suspension
We develop a lattice gas model for the drying of droplets of a nanoparticle
suspension on a planar surface, using dynamical density functional theory
(DDFT) to describe the time evolution of the solvent and nanoparticle density
profiles. The DDFT assumes a diffusive dynamics but does not include the
advective hydrodynamics of the solvent, so the model is relevant to highly
viscous or near to equilibrium systems. Nonetheless, we see an equivalent of
the coffee-ring stain effect, but in the present model it occurs for
thermodynamic rather the fluid-mechanical reasons. The model incorporates the
effect of phase separation and vertical density variations within the droplet
and the consequence of these on the nanoparticle deposition pattern on the
surface. We show how to include the effect of slip or no-slip at the surface
and how this is related to the receding contact angle. We also determine how
the equilibrium contact angle depends on the microscopic interaction
parameters.Comment: 35 pages, 10 figure
A General Catalogue of Molecular Hydrogen Emission-Line Objects (MHOs) in Outflows from Young Stars
We present a catalogue of Molecular Hydrogen emission-line Objects (MHOs) in
outflows from young stars, most of which are embedded. All objects are
identified in the near-infrared lines of molecular hydrogen, all reside in the
Milky Way, and all are associated with jets or molecular outflows from young
stars. Objects in both low and high-mass star forming regions are included.
This catalogue complements the existing database of Herbig-Haro objects;
indeed, for completeness, HH objects that are detected in H2 emission are
included in the MHO catalogue.Comment: 8 Pages, 5 figures. Accepted for publication in A&A. Searchable
catalogue/Data tables available from http://www.jach.hawaii.edu/UKIRT/MHCat
On nonlinear Tollmien-Schlichting/vortex interaction in three-dimensional boundary layers
The instability of an incompressible three-dimensional boundary layer (that is, one with cross-flow) is considered theoretically and computationally in the context of vortex/wave interactions. Specifically the work centers on two low amplitude, lower-branch Tollmien-Schlichting waves which mutually interact to induce a weak longitudinal vortex flow; the vortex motion, in turn, gives rise to significant wave-modulation via wall-shear forcing. The characteristic Reynolds number is taken as a large parameter and, as a consequence, the waves' and the vortex motion are governed primarily by triple-deck theory. The nonlinear interaction is captured by a viscous partial-differential system for the vortex coupled with a pair of amplitude equations for each wave pressure. Three distinct possibilities were found to emerge for the nonlinear behavior of the flow solution downstream - an algebraic finite-distance singularity, far downstream saturation or far-downstream wave-decay (leaving pure vortex flow) - depending on the input conditions, the wave angles, and the size of the cross-flow
The H2 velocity structure of inner knots in HH 212: asymmetries and rotation
High-resolution R~50 000 long-slit spectroscopy of the inner knots of the
highly symmetrical protostellar outflow HH 212 was obtained in the 1-0 S(1)
line of H2 at 2.12 micron with a spatial resolution of ~0.45 arcsec. At the
resulting velocity resolution of ~6 km s-1, multiple slit oriented observations
of the northern first knot NK1 clearly show double-peaked line profiles
consistent with either a radiative bow shock or dual (forward and reverse)
shocks. In contrast, the velocity distribution of the southern first knot SK1
remains single-peaked, suggesting a significantly lower jet velocity and
possibly a different density variation in the jet pulses in the southern flow
compared to the northern flow. Comparison with a semi-empirical analytical
model of bow shock emission allows us to constrain parameters such as the bow
inclination to the line of sight, the bow shock and jet velocities for each
flow. Although a few features are not reproduced by this model, it confirms the
presence of several dynamical and kinematical asymmetries between opposite
sides of the HH 212 bipolar jet. The position-velocity diagrams of both knots
exhibit complex dynamics that are broadly consistent with emission from a bow
shock and/or jet shock, which does not exclude jet rotation, although a clear
signature of jet rotation in HH 212 is missing. Alternative interpretations of
the variation of radial velocity across these knots, such as a variation in the
jet orientation, as well as for the velocity asymmetries between the flows, are
also considered. The presence of a correlation between flow velocity and
collimation in each flow is suggested.Comment: Accepted for publication in Astronomy and Astrophysics, 16 page
Inspection of commercial feeeding stuffs, 1943, Bulletin, no. 348
The Bulletin is a publication of the New Hampshire Agricultural Experiment Station, College of Life Sciences and Agriculture, University of New Hampshire, Durham, New Hampshire
Inspection of commercial feeeding stuffs, 1941, Bulletin, no. 333
The Bulletin is a publication of the New Hampshire Agricultural Experiment Station, College of Life Sciences and Agriculture, University of New Hampshire, Durham, New Hampshire
Inspection of commercial fertilizers for 1938, Bulletin, no. 311
The Bulletin is a publication of the New Hampshire Agricultural Experiment Station, College of Life Sciences and Agriculture, University of New Hampshire, Durham, New Hampshire
Inspection of commercial fertilizers for 1937, Bulletin, no. 301
The Bulletin is a publication of the New Hampshire Agricultural Experiment Station, College of Life Sciences and Agriculture, University of New Hampshire, Durham, New Hampshire
Inspection of commercial feeding stuffs, 1937, Bulletin, no. 297
The Bulletin is a publication of the New Hampshire Agricultural Experiment Station, College of Life Sciences and Agriculture, University of New Hampshire, Durham, New Hampshire
Inspection of commercial feeedingstuffs, Bulletin, no. 352
The Bulletin is a publication of the New Hampshire Agricultural Experiment Station, College of Life Sciences and Agriculture, University of New Hampshire, Durham, New Hampshire
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