5,824 research outputs found
Multilayer composite AZO/AGZO thin films for transparent conductive electrodes
Transparent electronics are an essential ingredient in many new technologies which are emerging in the 21st century - high efficiency solar cells[ll, interactive and transparent displays, energy efficient windows, and photonics for communications and computing[2J. The development of functionalised transparent conductive oxide materials (TCOs), in terms of abundant, cheap and environmentally friendly, is critical for materials science in such applications. Specifically, an impmiant research goal is to find substitutes for the dominant TCO material indium tin oxide (ITO), made from indium which is scarce, expensive and toxic. Zinc oxides doped with small amounts of aluminium (AZO), are promising candidates for such a substitute but generally don't perform as well as IT0[2l. Gallium co-doping with aluminium improves AZO performance significantly, but raises similar concerns to ITO, in terms of the scarcity and high cost of gallium.
This project aims to enhance the conductivity of AZO thin films-by adding a thin 'seed' layer co-doped with AI and minimum Ga concentration (AGZO). The project employed solution based sol-gel technique for synthesising AZO/GZO nanoparticles and then deposited on glass substrates through a spin coating process, followed by thermal annealing treatment. The optical properties, crystal structure and surface morphology of the films were characterised using UV-vis spectroscopy, X-ray diffraction and scanning electron microscopy. Composite multilayer films, with thickness around 400nm, exhibit transmittance above 90% across the visible range and resistivity approximately 10 O•cm.
Preliminary results indicate significant improvement in AZO films with the co-doped AGZO layer, compared with AZO films alone. Compared to uniformly doped AGZO films, the composite multilayer films exhibited similar performance, but with only 20% of the gallium consumed
Interactive Execution Monitoring of Agent Teams
There is an increasing need for automated support for humans monitoring the
activity of distributed teams of cooperating agents, both human and machine. We
characterize the domain-independent challenges posed by this problem, and
describe how properties of domains influence the challenges and their
solutions. We will concentrate on dynamic, data-rich domains where humans are
ultimately responsible for team behavior. Thus, the automated aid should
interactively support effective and timely decision making by the human. We
present a domain-independent categorization of the types of alerts a plan-based
monitoring system might issue to a user, where each type generally requires
different monitoring techniques. We describe a monitoring framework for
integrating many domain-specific and task-specific monitoring techniques and
then using the concept of value of an alert to avoid operator overload. We use
this framework to describe an execution monitoring approach we have used to
implement Execution Assistants (EAs) in two different dynamic, data-rich,
real-world domains to assist a human in monitoring team behavior. One domain
(Army small unit operations) has hundreds of mobile, geographically distributed
agents, a combination of humans, robots, and vehicles. The other domain (teams
of unmanned ground and air vehicles) has a handful of cooperating robots. Both
domains involve unpredictable adversaries in the vicinity. Our approach
customizes monitoring behavior for each specific task, plan, and situation, as
well as for user preferences. Our EAs alert the human controller when reported
events threaten plan execution or physically threaten team members. Alerts were
generated in a timely manner without inundating the user with too many alerts
(less than 10 percent of alerts are unwanted, as judged by domain experts)
Resonant X-Ray Scattering on the M-Edge Spectra from Triple-k Structure Phase in U_{0.75}Np_{0.25}O_{2} and UO_{2}
We derive an expression for the scattering amplitude of resonant x-ray
scattering under the assumption that the Hamiltonian describing the
intermediate state preserves spherical symmetry. On the basis of this
expression, we demonstrate that the energy profile of the RXS spectra expected
near U and Np M_4 edges from the triple-k antiferromagnetic ordering phase in
UO_{2} and U_{0.75}Np_{0.25}O_{2} agree well with those from the experiments.
We demonstrate that the spectra in the \sigma-\sigma' and \sigma-\pi' channels
exhibit quadrupole and dipole natures, respectively.Comment: 3 pages, 3 figures, to be published in J. Phys. Soc. Jpn. Supp
Comment on ``Two Time Scales and Violation of the Fluctuation-Dissipation Theorem in a Finite Dimensional Model for Structural Glasses''
In cond-mat/0002074 Ricci-Tersenghi et al. find two linear regimes in the
fluctuation-dissipation relation between density-density correlations and
associated responses of the Frustrated Ising Lattice Gas. Here we show that
this result does not seem to correspond to the equilibrium quantities of the
model, by measuring the overlap distribution P(q) of the density and comparing
the FDR expected on the ground of the P(q) with the one measured in the
off-equilibrium experiments.Comment: RevTeX, 1 page, 2 eps figures, Comment on F. Ricci-Tersenghi et al.,
Phys. Rev. Lett. 84, 4473 (2000
Soft X-ray resonant scattering study of single-crystal LaSrMnO
Soft X-ray resonant scattering studies at the Mn - and
the La - edges of single-crystal LaSrMnO are
reported. At low temperatures, below K, energy scans
with a fixed momentum transfer at the \emph{A}-type antiferromagnetic (0 0 1)
reflection around the Mn -edges with incident linear
and polarizations show strong resonant enhancements. The
splitting of the energy spectra around the Mn -edges may
indicate the presence of a mixed valence state, e.g., Mn/Mn. The
relative intensities of the resonance and the clear shoulder-feature as well as
the strong incident and polarization dependences strongly
indicate its complex electronic origin. Unexpected enhancement of the charge
Bragg (0 0 2) reflection at the La -edges with
polarization has been observed up to 300 K, with an anomaly appearing around
the orbital-ordering transition temperature, K,
suggesting a strong coupling (competition) between them.Comment: Accepted by European Physical Journal
Returning radiation in strong gravity around black holes: reverberation from the accretion disc
We study reflected X-ray emission that returns to the accretion disc in the strong gravitational fields around black holes using General Relativistic ray-tracing and radiative transfer calculations. Reflected X-rays that are produced when the inner regions of the disc are illuminated by the corona are subject to strong gravitational light bending, causing up to 47 per cent of the reflected emission to be returned to the disc around a rapidly spinning black hole, depending upon the scale height of the corona. The iron Kα line is enhanced relative to the continuum by 25 per cent, and the Compton hump by up to a factor of 3. Additional light traveltime between primary and secondary reflections increases the reverberation time lag measured in the iron K band by 49 per cent, while the soft X-ray lag is increased by 25 per cent and the Compton hump response time is increased by 60 per cent. Measured samples of X-ray reverberation lags are shown to be consistent with X-rays returning to the accretion disc in strong gravity. Understanding the effects of returning radiation is important in interpreting reverberation observations to probe black holes. Reflected X-rays returning to the disc can be uniquely identified by blueshifted returning iron K line photons that are Compton scattered from the inner disc, producing excess, delayed emission in the 3.5–4.5 keV energy range that will be detectable with forthcoming X-ray observatories, representing a unique test of General Relativity in the strong field limit
Returning radiation in strong gravity around black holes: Reverberation from the accretion disc
We study reflected X-ray emission that returns to the accretion disc in the
strong gravitational fields around black holes using General Relativistic ray
tracing and radiative transfer calculations. Reflected X-rays that are produced
when the inner regions of the disc are illuminated by the corona are subject to
strong gravitational light bending, causing up to 47 per cent of the reflected
emission to be returned to the disc around a rapidly spinning black hole,
depending upon the scale height of the corona. The iron K line is enhanced
relative to the continuum by 25 per cent, and the Compton hump by up to a
factor of three. Additional light travel time between primary and secondary
reflections increases the reverberation time lag measured in the iron K band by
49 per cent, while the soft X-ray lag is increased by 25 per cent and the
Compton hump response time is increased by 60 per cent. Measured samples of
X-ray reverberation lags are shown to be consistent with X-rays returning to
the accretion disc in strong gravity. Understanding the effects of returning
radiation is important in interpreting reverberation observations to probe
black holes. Reflected X-rays returning to the disc can be uniquely identified
by blueshifted returning iron K line photons that are Compton scattered from
the inner disc, producing excess, delayed emission in the 3.5-4.5keV energy
range that will be detectable with forthcoming X-ray observatories,
representing a unique test of General Relativity in the strong field limit.Comment: 20 pages, 14 figures. Accepted for publication in MNRA
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