26,619 research outputs found
Multiple imputation for sharing precise geographies in public use data
When releasing data to the public, data stewards are ethically and often
legally obligated to protect the confidentiality of data subjects' identities
and sensitive attributes. They also strive to release data that are informative
for a wide range of secondary analyses. Achieving both objectives is
particularly challenging when data stewards seek to release highly resolved
geographical information. We present an approach for protecting the
confidentiality of data with geographic identifiers based on multiple
imputation. The basic idea is to convert geography to latitude and longitude,
estimate a bivariate response model conditional on attributes, and simulate new
latitude and longitude values from these models. We illustrate the proposed
methods using data describing causes of death in Durham, North Carolina. In the
context of the application, we present a straightforward tool for generating
simulated geographies and attributes based on regression trees, and we present
methods for assessing disclosure risks with such simulated data.Comment: Published in at http://dx.doi.org/10.1214/11-AOAS506 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Robust semi-explicit model predictive control for hybrid automata
In this paper we propose an on-line design technique for the target control problem of hybrid automata. First, we compute on-line the shortest path, which has the minimum discrete cost, from an initial state to the given target set. Next, we derive a controller which successfully drives the system from the initial state to the target set while minimizing a cost function. The (robust) model predictive control (MPC) technique is used when the current state is not within a guard set, otherwise the (robust) mixed-integer predictive control (MIPC) technique is employed. An on-line, semi-explicit control algorithm is derived by combining the two techniques and applied on a high-speed and energy-saving control problem of the CPU processing
Parity restoration in the Highly Truncated Diagonalization Approach: application to the outer fission barrier of Pu
The restoration of the parity symmetry has been performed in the framework of
the Highly Truncated Diagonalization Approach suited to treat correlations in
an explicitly particle-number conserving microscopic approach. To do so we have
assumed axial symmetry and used a generalized Wick's theorem due to L\"owdin in
a projection-after-variation scheme. We have chosen the Skyrme SkM
energy-density functional for the particle-hole channel and a
density-independent delta force for the residual interaction. We have applied
this approach in the region of the outer fission barrier of the Pu
nucleus. As a result, we have shown that the fission isomeric
state is statically unstable against intrinsic-parity breaking modes, while the
projection does not affect the energy at the top of the intrinsic outer fission
barrier. Altogether, this leads to an increase of the height of the outer
fission barrier--with respect to the fission isomeric state--by about 350 keV,
affecting thus significantly the fission-decay lifetime of the considered
fission isomer
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