37,563 research outputs found
Analytical studies of nuclear light bulb engine radiant heat transfer and performance characteristics
Analytical model of nuclear light bulb engine radiant heat transfer and engine performance, dynamics and control, heat loads and shutdown characteristic
Regularization independent of the noise level: an analysis of quasi-optimality
The quasi-optimality criterion chooses the regularization parameter in
inverse problems without taking into account the noise level. This rule works
remarkably well in practice, although Bakushinskii has shown that there are
always counterexamples with very poor performance. We propose an average case
analysis of quasi-optimality for spectral cut-off estimators and we prove that
the quasi-optimality criterion determines estimators which are rate-optimal
{\em on average}. Its practical performance is illustrated with a calibration
problem from mathematical finance.Comment: 18 pages, 3 figure
Runtime Verification of Temporal Properties over Out-of-order Data Streams
We present a monitoring approach for verifying systems at runtime. Our
approach targets systems whose components communicate with the monitors over
unreliable channels, where messages can be delayed or lost. In contrast to
prior works, whose property specification languages are limited to
propositional temporal logics, our approach handles an extension of the
real-time logic MTL with freeze quantifiers for reasoning about data values. We
present its underlying theory based on a new three-valued semantics that is
well suited to soundly and completely reason online about event streams in the
presence of message delay or loss. We also evaluate our approach
experimentally. Our prototype implementation processes hundreds of events per
second in settings where messages are received out of order.Comment: long version of the CAV 2017 pape
Studies of nuclear light bulb start-up conditions and engine dynamics
Deep Space Network for two-way communications with unmanned spacecraft at planetary distances - Vol.
Momentum distributions in time-dependent density functional theory: Product phase approximation for non-sequential double ionization in strong laser fields
We investigate the possibility to deduce momentum space properties from
time-dependent density functional calculations. Electron and ion momentum
distributions after double ionization of a model Helium atom in a strong
few-cycle laser pulse are studied. We show that, in this case, the choice of
suitable functionals for the observables is considerably more important than
the choice of the correlation potential in the time-dependent Kohn-Sham
equations. By comparison with the solution of the time-dependent Schroedinger
equation, the insufficiency of functionals neglecting electron correlation is
demonstrated. We construct a functional of the Kohn-Sham orbitals, which in
principle yields the exact momentum distributions of the electrons and the ion.
The product-phase approximation is introduced, which reduces the problem of
approximating this functional significantly.Comment: 8 pages, 5 figures, RevTeX
Clear and Compress: Computing Persistent Homology in Chunks
We present a parallelizable algorithm for computing the persistent homology
of a filtered chain complex. Our approach differs from the commonly used
reduction algorithm by first computing persistence pairs within local chunks,
then simplifying the unpaired columns, and finally applying standard reduction
on the simplified matrix. The approach generalizes a technique by G\"unther et
al., which uses discrete Morse Theory to compute persistence; we derive the
same worst-case complexity bound in a more general context. The algorithm
employs several practical optimization techniques which are of independent
interest. Our sequential implementation of the algorithm is competitive with
state-of-the-art methods, and we improve the performance through parallelized
computation.Comment: This result was presented at TopoInVis 2013
(http://www.sci.utah.edu/topoinvis13.html
Dependence of the before-relaxation energy transfer in mixed solutions of dyes on the overlap of their absorption spectra
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