20,427 research outputs found
Synthesis and evaluation of new high polymers for coating applications annual summary report no. 1, 26 jun. 1964 - 25 jun. 1965
Synthesis of organic and semi-organic polymers useful as high temperature coating materia
Synthesis and evaluation of new high temperature polymers for coating applications Technical summary report, 26 Jun. 1964 - 25 Sep. 1966
Synthesis, characterization, and evaluation of organic and semiorganic heat resistant polymer coating
Mapping warm molecular hydrogen with Spitzer's Infrared Array Camera (IRAC)
Photometric maps, obtained with Spitzer's Infrared Array Camera (IRAC), can
provide a valuable probe of warm molecular hydrogen within the interstellar
medium. IRAC maps of the supernova remnant IC443, extracted from the Spitzer
archive, are strikingly similar to spectral line maps of the H2 pure rotational
transitions that we obtained with the Infrared Spectrograph (IRS) instrument on
Spitzer. IRS spectroscopy indicates that IRAC Bands 3 and 4 are indeed
dominated by the H2 v=0-0 S(5) and S(7) transitions, respectively. Modeling of
the H2 excitation suggests that Bands 1 and 2 are dominated by H2 v=1-0 O(5)
and v=0-0 S(9). Large maps of the H2 emission in IC433, obtained with IRAC,
show band ratios that are inconsistent with the presence of gas at a single
temperature. The relative strengths of IRAC Bands 2, 3, and 4 are consistent
with pure H2 emission from shocked material with a power-law distribution of
gas temperatures. CO vibrational emissions do not contribute significantly to
the observed Band 2 intensity. Assuming that the column density of H2 at
temperatures T to T+dT is proportional to T raised to the power -b for
temperatures up to 4000 K, we obtained a typical estimate of 4.5 for b. The
power-law index, b, shows variations over the range 3 to 6 within the set of
different sight-lines probed by the maps, with the majority of sight-lines
showing b in the range 4 to 5. The observed power-law index is consistent with
the predictions of simple models for paraboloidal bow shocks.Comment: 27 pages, including 11 figures. Accepted for publication in Ap
Coupled complex Ginzburg-Landau systems with saturable nonlinearity and asymmetric cross-phase modulation
We formulate and study dynamics from a complex Ginzburg-Landau system with
saturable nonlinearity, including asymmetric cross-phase modulation (XPM)
parameters. Such equations can model phenomena described by complex
Ginzburg-Landau systems under the added assumption of saturable media. When the
saturation parameter is set to zero, we recover a general complex cubic
Ginzburg-Landau system with XPM. We first derive conditions for the existence
of bounded dynamics, approximating the absorbing set for solutions. We use this
to then determine conditions for amplitude death of a single wavefunction. We
also construct exact plane wave solutions, and determine conditions for their
modulational instability. In a degenerate limit where dispersion and
nonlinearity balance, we reduce our system to a saturable nonlinear
Schr\"odinger system with XPM parameters, and we demonstrate the existence and
behavior of spatially heterogeneous stationary solutions in this limit. Using
numerical simulations we verify the aforementioned analytical results, while
also demonstrating other interesting emergent features of the dynamics, such as
spatiotemporal chaos in the presence of modulational instability. In other
regimes, coherent patterns including uniform states or banded structures arise,
corresponding to certain stable stationary states. For sufficiently large yet
equal XPM parameters, we observe a segregation of wavefunctions into different
regions of the spatial domain, while when XPM parameters are large and take
different values, one wavefunction may decay to zero in finite time over the
spatial domain (in agreement with the amplitude death predicted analytically).
While saturation will often regularize the dynamics, such transient dynamics
can still be observed - and in some cases even prolonged - as the saturability
of the media is increased, as the saturation may act to slow the timescale.Comment: 36 page
Effects of Vacancies on Properties of Relaxor Ferroelectrics: a First-Principles Study
A first-principles-based model is developed to investigate the influence of
lead vacancies on the properties of relaxor ferroelectric Pb(Sc1/2Nb1/2)O3
(PSN). Lead vacancies generate large, inhomogeneous, electric fields that
reduce barriers between energy minima for different polarization directions.
This naturally explains why relaxors with significant lead vacancy
concentrations have broadened dielectric peaks at lower temperatures, and why
lead vacancies smear properties in the neighborhood of the ferroelectric
transition in PSN. We also reconsider the conventional wisdom that lead
vacancies reduce the magnitude of dielectric response.Comment: 11 pages, 1 figur
CONSUMER PREFERENCES FOR ELECTRICITY FROM BIOENERGY AND OTHER RENEWABLES
This study ascertains residential electricity consumers' support and willingness to pay for electricity from renewable sources. Then, willingness to pay for specified renewable energy sources (solar, wind, landfill wastes, bioenergy from fast growing crops, and bioenergy from forest products wastes). Effects of demographics and environmental behaviors are estimated.Institutional and Behavioral Economics,
Design comparison of cesium and potassium vapor turbine-generator units for space power
Design comparison of cesium and potassium vapor turbogenerator units for space power plant
Is a Specialist Employment Court a Better Forum for women?
A series of seminars on "Women and Employment" were held at Victoria University of Wellington in July 1997. The topic of the seminar was whether a specialist employment court is a better forum for women. The following article is based on Maxine Gay's speech at the seminar. She believes that although the Employment Court may have made gender biased decisions, the Court should nevertheless be retained. She argues that a specialist employment court is important for women because it recognises that the employment contract is one in which the parties have unequal power and it should therefore be treated differently from other contracts. She takes the view that the suggestion by the Business Round Table and Employers' Federation to abolish the Employment Court is part of a wider agenda to casualise the labour force and reduce the rights of employees. 
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