22,371 research outputs found
Convergence properties of simple genetic algorithms
The essential parameters determining the behaviour of genetic algorithms were investigated. Computer runs were made while systematically varying the parameter values. Results based on the progress curves obtained from these runs are presented along with results based on the variability of the population as the run progresses
Condensation cyclization reactions of electron deficient aromatics. 4: Tricyclic nitropropene nitronates from the reaction of phloroglucinol and cycloalkanones with sym-trinitrobenzene
Interesting similarities have been shown between the reactions of sym-trinitrobenzene with cycloalkanones, and with phloroglucinol. Previously unsuspected common intermediates have been shown to intervene. The structurally similar products in each case are tricyclic nitropropene nitronates. Protonation of these yields the corresponding nitronic acids in certain instances
Advanced superconducting magnets investigation
Mathematical models for steady state behavior of composite superconductors and experimental verification using magnet coi
On the regional climatic impact of contrails: microphysical and radiative properties of contrails and natural cirrus clouds
International audienceThe impact of contrail-induced cirrus clouds on regional climate is estimated for mean atmospheric conditions of southern Germany in the months of July and October. This is done by use of a regionalized one-dimensional radiative convective model (RCM). The influence of an increased ice cloud cover is studied by comparing RCM results representing climatological values with a modified case. In order to study the sensitivity of this effect on the radiative characteristics of the ice cloud, two types of additional ice clouds were modelled: cirrus and contrails, the latter cloud type containing a higher number of smaller and less of the larger cloud particles. Ice cloud parameters are calculated on the basis of a particle size distribution which covers the range from 2 to 2000 µm, taking into consideration recent measurements which show a remarkable amount of particles smaller than 20 µm. It turns out that a 10% increase in ice cloud cover leads to a surface temperature increase in the order of 1K, ranging from 1.1 to 1.2K in July and from 0.8 to 0.9K in October depending on the radiative characteristics of the air-traffic-induced ice clouds. Modelling the current contrail cloud cover which is near 0.5% over Europe yields a surface temperature increase in the order of 0.05K
Transition Decomposition of Quantum Mechanical Evolution
We show that the existence of the family of self-adjoint Lyapunov operators
introduced in [J. Math. Phys. 51, 022104 (2010)] allows for the decomposition
of the state of a quantum mechanical system into two parts: A past time
asymptote, which is asymptotic to the state of the system at t goes to minus
infinity and vanishes at t goes to plus infinity, and a future time asymptote,
which is asymptotic to the state of the system at t goes to plus infinity and
vanishes at t goes to minus infinity. We demonstrate the usefulness of this
decomposition for the description of resonance phenomena by considering the
resonance scattering of a particle off a square barrier potential. We show that
the past time asymptote captures the behavior of the resonance. In particular,
it exhibits the expected exponential decay law and spatial probability
distribution.Comment: Accepted for publication in Int. J. Theor. Phy
Do broad absorption line quasars live in different environments from ordinary quasars?
We select a sample of traditionally defined broad absorption line
quasars (BALQs) from the Fifth Data Release quasar catalog of the Sloan Digital
Sky Survey. For a statistically homogeneous quasar sample with , the BAL quasar fraction is and is almost constant with
redshift. We measure the auto-correlation of non-BAL quasars (nonBALQs) and the
cross-correlation of BALQs with nonBALQs using this statistically homogeneous
sample, both in redshift space and using the projected correlation function. We
find no significant difference between the clustering strengths of BALQs and
nonBALQs. Assuming a power-law model for the real space correlation function
, the correlation length for nonBALQs is ; for BALQs, the cross-correlation length is . Our clustering results suggest that BALQs live in similar
large-scale environments as do nonBALQs.Comment: accepted for publication in Ap
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