6,658 research outputs found
Saturation and shadowing in high-energy proton-nucleus dilepton production
We discuss the inclusive dilepton cross section for proton (quark)-nucleus
collisions at high energies in the very forward rapidity region. Starting from
the calculation in the quasi-classical approximation, we include low-x
evolution effects in the nucleus and predict leading twist shadowing together
with anomalous scaling behaviour.Comment: 32 pages, LaTex, 6 figures, a few modifications of the tex
An overview of large wind turbine tests by electric utilities
A summary of recent plants and experiences on current large wind turbine (WT) tests being conducted by electric utilities is provided. The test programs discussed do not include federal research and development (R&D) programs, many of which are also being conducted in conjunction with electric utilities. The information presented is being assembled in a project, funded by the Electric Power Research Institute (EPRI), the objective of which is to provide electric utilities with timely summaries of test performance on key large wind turbines. A summary of key tests, test instrumentation, and recent results and plans is given. During the past year, many of the utility test programs initiated have encountered test difficulties that required specific WT design changes. However, test results to date continue to indicate that long-term machine performance and cost-effectiveness are achievable
Investigation of the utility of mean square approximation systems and in system response predictions
A method is presented for estimating the variability of a system's natural frequencies arising from the variability of the system's parameters. The only information required to obtain the estimates is the member variability, in the form of second order properties, and the natural frequencies and mode shapes of the mean system. Several examples are worked out in detail to illustrate how the method is applied
Loop Groups and Discrete KdV Equations
A study is presented of fully discretized lattice equations associated with
the KdV hierarchy. Loop group methods give a systematic way of constructing
discretizations of the equations in the hierarchy. The lattice KdV system of
Nijhoff et al. arises from the lowest order discretization of the trivial,
lowest order equation in the hierarchy, b_t=b_x. Two new discretizations are
also given, the lowest order discretization of the first nontrivial equation in
the hierarchy, and a "second order" discretization of b_t=b_x. The former,
which is given the name "full lattice KdV" has the (potential) KdV equation as
a standard continuum limit. For each discretization a Backlund transformation
is given and soliton content analyzed. The full lattice KdV system has, like
KdV itself, solitons of all speeds, whereas both other discretizations studied
have a limited range of speeds, being discretizations of an equation with
solutions only of a fixed speed.Comment: LaTeX, 23 pages, 1 figur
The Cosmological Kibble Mechanism in the Laboratory: String Formation in Liquid Crystals
We have observed the production of strings (disclination lines and loops) via
the Kibble mechanism of domain (bubble) formation in the isotropic to nematic
phase transition of a sample of uniaxial nematic liquid crystal. The probablity
of string formation per bubble is measured to be . This is in
good agreement with the theoretical value expected in two dimensions
for the order parameter space of a simple uniaxial nematic
liquid crystal.Comment: 17 pages, in TEX, 2 figures (not included, available on request
Does parton saturation at high density explain hadron multiplicities at LHC?
An addendum to our previous papers in Phys. Lett. B539 (2002) 46 and Phys.
Lett. B502 (2001) 51, contributed to the CERN meeting "First data from the LHC
heavy ion run", March 4, 2011Comment: 6 pages, contribution to the CERN meeting "First data from the LHC
heavy ion run", March 4, 201
Quenching of hadron spectra in media
We determine how the yield of large transverse momentum hadrons is modified
due to induced gluon radiation off a hard parton traversing a QCD medium. The
quenching factor is formally a collinear- and infrared-safe quantity and can be
treated perturbatively. In spite of that, in the region of practical
interest, its value turns out to be extremely sensitive to large distances and
can be used to unravel the properties of dense quark-gluon final states
produced in heavy ion collisions. We also find that the standard modelling of
quenching by shifting in the hard parton cross section by the mean
energy loss is inadequate.Comment: 20 pp, 5 eps figure
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The development, testing and assessment of a model for establishing perceived community needs for career education alternatives.
EducationDoctor of Education (Ed.D.
Carrier Drift-Mobilities and Solar Cell Models for Amorphous and Nanocrystalline Silicon
Hole drift mobilities in hydrogenated amorphous silicon (a-Si:H) and nanocrystalline silicon (nc-Si:H) are in the range of 10-3 to 1 cm2/Vs at room-temperature. These low drift mobilities establish corresponding hole mobility limits to the power generation and useful thicknesses of the solar cells. The properties of as-deposited a-Si:H nip solar cells are quite close to their hole mobility limit, but the corresponding limit has not been examined for nc-Si:H solar cells. We explore the predictions for nc-Si:H solar cells based on parameters and values estimated from hole drift-mobility and related measurements. The indicate that the hole mobility limit for nc-Si:H cells corresponds to an optimum intrinsic-layer thickness of 2-3 2m, whereas the best nc-Si:H solar cells (10% conversion efficiency) have thicknesses around 2 2m
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