3,076 research outputs found
Bio-IGCC with CCS as a long-term mitigation option in a coupled energy-system and land-use model
This study analyses the impact of techno-economic performance of the BIGCC process and the effect of different biomass feedstocks on the technology's long term deployment in climate change mitigation scenarios. As the BIGCC technology demands high amounts of biomass raw material it also affects the land-use sector and is dependent on conditions and constraints on the land-use side. To represent the interaction of biomass demand and supply side the global energy-economy-climate model ReMIND is linked to the global land-use model MAgPIE. The link integrates biomass demand and price as well as emission prices and land-use emissions. Results indicate that BIGCC with CCS could serve as an important mitigation option and that it could even be the main bioenergy conversion technology sharing 33% of overall mitigation in 2100. The contribution of BIGCC technology to long-term climate change mitigation is much higher if grass is used as fuel instead of wood, provided that the grass-based process is highly efficient. The capture rate has to significantly exceed 60 % otherwise the technology is not applied. The overall primary energy consumption of biomass reacts much more sensitive to price changes of the biomass than to technoeconomic performance of the BIGCC process. As biomass is mainly used with CCS technologies high amounts of carbon are captured ranging from 130 GtC to 240 GtC (cumulated from 2005-2100) in different scenarios
On Proper Polynomial Maps of
Two proper polynomial maps are said to be \emph{equivalent} if there exist such that .
We investigate proper polynomial maps of arbitrary topological degree up to equivalence. Under the further assumption that the maps are Galois
coverings we also provide the complete description of equivalence classes. This
widely extends previous results obtained by Lamy in the case .Comment: 15 pages. Final version, to appear in Journal of Geometric Analysi
High-resolution microwave frequency dissemination on an 86-km urban optical link
We report the first demonstration of a long-distance ultra stable frequency
dissemination in the microwave range. A 9.15 GHz signal is transferred through
a 86-km urban optical link with a fractional frequency stability of 1.3x10-15
at 1 s integration time and below 10-18 at one day. The optical link phase
noise compensation is performed with a round-trip method. To achieve such a
result we implement light polarisation scrambling and dispersion compensation.
This link outperforms all the previous radiofrequency links and compares well
with recently demonstrated full optical links.Comment: 11 pages, 5 figure
Cold nuclear matter effects on J/psi production: intrinsic and extrinsic transverse momentum effects
Cold nuclear matter effects on J/psi production in proton-nucleus and
nucleus-nucleus collisions are evaluated taking into account the specific J/psi
production kinematics at the partonic level, the shadowing of the initial
parton distributions and the absorption in the nuclear matter. We consider two
different parton processes for the c-cbar pair production: one with collinear
gluons and a recoiling gluon in the final state and the other with initial
gluons carrying intrinsic transverse momentum. Our results are compared to RHIC
observables. The smaller values of the nuclear modification factor R_AA in the
forward rapidity region (with respect to the mid rapidity region) are partially
explained, therefore potentially reducing the need for recombination effects.Comment: 7 pages, 11 figures, LaTeX, uses elsarticle.cls (included).v2:
version (with minor text revisions and Fig 2 and 4a modified) to appear in
Phys.Lett.
Superconductivity and Electronic Structure of Perovskite MgCNi3
The electronic structure, stability, electron phonon coupling and
superconductivity of the non-oxide perovskite MgCNi are studied using
density functional calculations. The band structure is dominated by a Ni
derived density of states peak just below the Fermi energy, which leads to a
moderate Stoner enhancement, placing MgCNi in the range where spin
fluctuations may noticeably affect transport, specific heat and
superconductivity, providing a mechanism for reconciling various measures of
the coupling . Strong electron phonon interactions are found for the
octahedral rotation mode and may exist for other bond angle bending modes. The
Fermi surface contains nearly cancelling hole and electron sheets that give
unusual behavior of transport quantities particularly the thermopower. The
results are discussed in relation to the superconductivity of MgCNi.Comment: 4 pages, RevTex, 5 ps figure
Theories for multiple resonances
Two microscopic theories for multiple resonances in nuclei are compared,
n-particle-hole RPA and quantized Time-Dependent Hartree-Fock (TDHF). The
Lipkin-Meshkov-Glick model is used as test case. We find that quantized TDHF is
superior in many respects, except for very small systems.Comment: 14 Pages, 3 figures available upon request
Generic Rotation in a Collective SD Nucleon-Pair Subspace
Low-lying collective states involving many nucleons interacting by a random
ensemble of two-body interactions (TBRE) are investigated in a collective
SD-pair subspace, with the collective pairs defined dynamically from the
two-nucleon system. It is found that in this truncated pair subspace collective
vibrations arise naturally for a general TBRE hamiltonian whereas collective
rotations do not. A hamiltonian restricted to include only a few randomly
generated separable terms is able to produce collective rotational behavior, as
long as it includes a reasonably strong quadrupole-quadrupole component.
Similar results arise in the full shell model space. These results suggest that
the structure of the hamiltonian is key to producing generic collective
rotation.Comment: 11 pages, 5 figure
The large longitudinal spread of solar energetic particles during the January 17, 2010 solar event
We investigate multi-spacecraft observations of the January 17, 2010 solar
energetic particle event. Energetic electrons and protons have been observed
over a remarkable large longitudinal range at the two STEREO spacecraft and
SOHO suggesting a longitudinal spread of nearly 360 degrees at 1AU. The flaring
active region, which was on the backside of the Sun as seen from Earth, was
separated by more than 100 degrees in longitude from the magnetic footpoints of
each of the three spacecraft. The event is characterized by strongly delayed
energetic particle onsets with respect to the flare and only small or no
anisotropies in the intensity measurements at all three locations. The presence
of a coronal shock is evidenced by the observation of a type II radio burst
from the Earth and STEREO B. In order to describe the observations in terms of
particle transport in the interplanetary medium, including perpendicular
diffusion, a 1D model describing the propagation along a magnetic field line
(model 1) (Dr\"oge, 2003) and the 3D propagation model (model 2) by (Dr\"oge et
al., 2010) including perpendicular diffusion in the interplanetary medium have
been applied, respectively. While both models are capable of reproducing the
observations, model 1 requires injection functions at the Sun of several hours.
Model 2, which includes lateral transport in the solar wind, reveals high
values for the ratio of perpendicular to parallel diffusion. Because we do not
find evidence for unusual long injection functions at the Sun we favor a
scenario with strong perpendicular transport in the interplanetary medium as
explanation for the observations.Comment: The final publication is available at http://www.springerlink.co
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