19,113 research outputs found
Encapsulation Processing and Manufacturing Yield Analysis
The development of encapsulation processing and a manufacturing productivity analysis for photovoltaic cells are discussed. The goals were: (1) to understand the relationships between both formulation variables and process variables; (2) to define conditions required for optimum performance; (3) to predict manufacturing yield; and (4) to provide documentation to industry
A deep, narrow J-band search for proto-galactic Lyman Alpha emission at redshifts z~9
We present a deep, narrow J-band search for proto--galactic Lyman Alpha
emission at redshifts z~9. We combine an exceptionally deep image of the Hubble
Deep Field South, obtained using a narrow band filter centred on the wavelength
1.187 microns using the VLT/ISAAC facility, with existing deep, broad band
images covering optical to near infrared wavelengths. We search for z~9 Lyman
Alpha emitting galaxies displaying a significant narrow band excess relative to
the Js-band that are undetected at optical wavelengths. We detect no sources
consistent with this criterion to the 90% point source flux limit of the NB
image, F_{NB} = 3.28 x 10^{-18} ergs/s/cm2. The survey selection function
indicates that we have sampled a volume of approximately 340 h^{-3} Mpc^3 to a
Lyman Alpha emission luminosity of 10^{43} h^{-2} ergs/s. We conclude by
considering the potential implications for the physics of the high--redshift
universe.Comment: 11 pages, accepted MNRAS. Please note that the automatic postscript
generation may result in a corrupted postscript file. Please use
ftp://astroftp.phys.uvic.ca/pub/jwillis/jwillis_zen1.ps.gz to obtain an
uncorrupted versio
Coherent structures in localised and global pipe turbulence
The recent discovery of unstable travelling waves (TWs) in pipe flow has been
hailed as a significant breakthrough with the hope that they populate the
turbulent attractor. We confirm the existence of coherent states with internal
fast and slow streaks commensurate in both structure and energy with known TWs
using numerical simulations in a long pipe. These only occur, however, within
less energetic regions of (localized) `puff' turbulence at low Reynolds numbers
(Re=2000-2400), and not at all in (homogeneous) `slug' turbulence at Re=2800.
This strongly suggests that all currently known TWs sit in an intermediate
region of phase space between the laminar and turbulent states rather than
being embedded within the turbulent attractor itself. New coherent fast streak
states with strongly decelerated cores appear to populate the turbulent
attractor instead.Comment: As accepted for PRL. 4 pages, 6 figures. Alterations to figs. 4,5.
Significant changes to tex
Investigation of Test Methods, Material Properties and Processes for Solar Cell Encapsulants
The evaluation of potentially useful low cost encapsulation materials is discussed. The goal is to identify, evaluate, test and recommend encapsulant materials and processes for the production of cost effective, long life solar cell modules. Technical investigations concerned the development of advanced cure chemistries for lamination type pottants; the continued evaluation of soil resistant surface treatment, and the results of an accelerated aging test program for the comparison of material stabilities. New compounds were evaluated for efficiency in curing both ethylene/vinyl acetate and ethylene/methyl acrylate pottants intended for vacuum bag lamination of solar cells. Two component aliphatic urethane casting syrups were evaluated for suitability as solar module pottants on the basis of optical, physical and fabrication characteristics
What's up prof? Current issues in the visual effects & post-production industry
We interviewed creative professionals at a number of London visual effects and post-production houses. We report on the key issues raised in those interviews: desirable new technologies, infrastructure challenges, personnel and process management
Reply to Comment on 'Critical behaviour in the relaminarization of localized turbulence in pipe flow'
This is a Reply to Comment arXiv:0707.2642 by Hof et al. on Letter
arXiv:physics/0608292 which was subsequently published in Phys Rev Lett, 98,
014501 (2007).
In our letter it was reported that in pipe flow the median time for
relaminarisation of localised turbulent disturbances closely follows the
scaling . This conclusion was based on data from
collections of 40 to 60 independent simulations at each of six different
Reynolds numbers, Re. In the Comment, Hof et al. estimate differently
for the point at lowest Re. Although this point is the most uncertain, it forms
the basis for their assertion that the data might then fit an exponential
scaling , for some constant A, supporting Hof et al.
(2006) Nature, 443, 59. The most certain point (at largest Re) does not fit
their conclusion and is rejected. We clarify why their argument for rejecting
this point is flawed. The median is estimated from the distribution of
observations, and it is shown that the correct part of the distribution is
used. The data is sufficiently well determined to show that the exponential
scaling cannot be fit to the data over this range of Re, whereas the fit is excellent, indicating critical behaviour and supporting
experiments by Peixinho & Mullin 2006.Comment: 1 page, 1 figur
Hydromagnetic Taylor--Couette flow: wavy modes
We investigate magnetic Taylor--Couette flow in the presence of an imposed
axial magnetic field. First we calculate nonlinear steady axisymmetric
solutions and determine how their strength depends on the applied magnetic
field. Then we perturb these solutions to find the critical Reynolds numbers
for the appearance of wavy modes, and the related wavespeeds, at increasing
magnetic field strength. We find that values of imposed magnetic field which
alter only slightly the transition from circular--Couette flow to
Taylor--vortex flow, can shift the transition from Taylor--vortex flow to wavy
modes by a substantial amount. The results are compared against onset in the
absence of a magnetic field.Comment: 12 pages, 8 figures. To appear in J. Fluid Mech. To appear in J.
Fluid Mec
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